Carbon Dioxide Capture and Conversion: Advanced Materials and Processes 9780323855853

Citation preview

Carbon Dioxide Capture and Conversion

Carbon Dioxide Capture and Conversion Advanced Materials and Processes

Edited by

SONIL NANDA Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

DAI-VIET N. VO Center of Excellence for Green Energy and Environmental Nanomaterials, Nguyen Tat Thanh University, Ho Chi Minh City, Vietnam

VAN-HUY NGUYEN Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education, Kelambakkam, Tamil Nadu, India

Elsevier Radarweg 29, PO Box 211, 1000 AE Amsterdam, Netherlands The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, United Kingdom 50 Hampshire Street, 5th Floor, Cambridge, MA 02139, United States Copyright © 2022 Elsevier B.V. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. ISBN: 978-0-323-85585-3 For Information on all Elsevier publications visit our website at https://www.elsevier.com/books-and-journals

Publisher: Susan Dennis Editorial Project Manager: Emerald Li Production Project Manager: Sujatha Thirugnana Sambandam Cover Designer: Christian J. Bilbow Typeset by MPS Limited, Chennai, India

Contents List of contributors About the editors Preface

1. A brief overview of recent advancements in CO2 capture and valorization technologies

xi xv xix

1

Biswa R. Patra, Shiva P. Gouda, Falguni Pattnaik, Sonil Nanda, Ajay K. Dalai and Satyanarayan Naik 1.1 Introduction 1.2 CO2 emissions 1.3 CO2 capture and storage technologies 1.4 Valorization of CO2 to produce valuable chemicals 1.5 Conclusions Acknowledgments References

2. Sustainable utilization of CO2 toward a circular economy: prospects, challenges, and opportunities

1 3 4 9 12 12 12

17

Bamidele Victor Ayodele, Siti Indati Mustapa, May Ali Alsaffar and Dai-Viet N. Vo 2.1 Introduction 2.2 Overview of pathways for CO2 emissions 2.2.1 CO2 emissions in residential and commercial building 2.2.2 CO2 emissions in industrial processes 2.2.3 CO2 emissions in the transportation sector 2.2.4 CO2 emissions electricity generation 2.3 Strategies and circular economic model for mitigation of CO2 emissions and its sustainable utilization 2.3.1 Strategies for CO2 emission reduction 2.4 Processes for sustainable utilization of CO2 for value-added products 2.4.1 CO2 reforming of hydrocarbon and biomass 2.4.2 CO2 hydrogenation to renewable fuels and value-added products 2.5 Overcoming the challenges of CO2 valorization to sustainable products 2.6 Conclusions References

17 19 20 21 22 22 24 24 27 28 29 31 32 33

v

vi

Contents

3. CO2 conversion technologies for clean fuels production

37

Ahmad Salam Farooqi, Mohammad Yusuf, Noor Asmawati Mohd Zabidi, Khairuddin Sanaullah and Bawadi Abdullah 3.1 Introduction 3.2 Methods for CO2 conversion 3.3 CO2 conversion into methanol 3.4 CO2 conversion into synthesis gas 3.5 CO2 conversion to methane (methanation) reaction 3.6 CO2 conversion into dimethyl ether 3.7 CO2 conversion into gasoline 3.8 Conclusions Acknowledgments References

4. Upcycling of carbon from waste via bioconversion into biofuel and feed

37 38 39 43 46 51 55 58 58 58

65

Siew Yoong Leong, Shamsul Rahman Mohamed Kutty, Pak Yan Moh and Qunliang Li Abbreviations 4.1 Introduction 4.2 Upcycling of CO2 by microalgae 4.3 Upcycling of carbon by insect larvae 4.4 Biomethanation of CO2 by anaerobic digestion 4.5 Importance of bioconversion in circular bioeconomy 4.6 Opportunity and challenges in bioconversion of carbon source 4.7 Conclusions References

65 65 66 72 80 80 82 86 86

5. Organic base-mediated fixation of CO2 into value-added chemicals

93

Cong Chien Truong and Dinesh Kumar Mishra Abbreviations 5.1 Introduction 5.2 Organic base-mediated transformation of CO2 into value-added products 5.2.1 Linear/cyclic urea and carbamoyl azides 5.2.2 Linear/cyclic carbamates 5.2.3 Linear/cyclic carbonates 5.2.4 Polyureas
polycarbonates 5.2.5 CO2 reduction-derived products

93 94 95 95 97 98 103 105

Contents

5.2.6 Carboxylic acids and their ester derivatives 5.2.7 Five-membered heterocycles 5.2.8 Six-membered heterocycles 5.3 Conclusions References

6. Catalytic conversion of CO2 into methanol

vii 109 111 114 120 120

129

Nor Hafizah Berahim and Noor Asmawati Mohd Zabidi Abbreviations 6.1 Introduction 6.2 Methanol uses and applications 6.2.1 Chemical feedstock 6.2.2 Energy source 6.2.3 Other uses 6.2.4 Industrial methanol synthesis 6.2.5 Hydrogenation of CO2 into methanol 6.3 CO2 activation and its thermodynamic challenges for methanol reduction 6.4 Catalysts for hydrogenation of CO2 into methanol 6.4.1 Cu/ZnO-based catalysts 6.4.2 Catalyst supports 6.4.3 Catalyst promoters 6.5 Factors affecting methanol synthesis 6.5.1 Catalyst pretreatment 6.5.2 Reaction conditions 6.6 Deactivation of the catalysts 6.7 Conclusions References

7. Application of calcium looping (CaL) technology for CO2 capture

129 130 131 131 132 132 132 133 135 136 136 138 142 145 145 148 153 154 155

163

Nader Mahinpey, Seyed Mojtaba Hashemi, S. Toufigh Bararpour and Davood Karami 7.1 Introduction 7.2 Calcium looping process 7.3 Reactivity decay of CaO-based sorbents 7.3.1 Sintering 7.3.2 Reaction with impurities 7.3.3 Attrition

163 164 167 168 170 170

viii

Contents

7.4 Natural and synthetic CaO-based sorbents 7.4.1 Natural sorbents 7.4.2 Synthetic sorbents 7.5 Kinetics modeling of calcium looping process 7.6 Conclusions and perspectives References

8. Dry reforming of methane and biogas to produce syngas: a review of catalysts and process conditions

172 173 181 188 192 194

201

Zahra Alipour, Venu Babu Borugadda, Hui Wang and Ajay K. Dalai Abbreviations 8.1 Introduction 8.2 Heterogeneous catalyst for dry reforming 8.2.1 Noble metal-based catalyst 8.2.2 Nonnoble metal-based catalysts 8.2.3 Bimetallic catalysts 8.3 Effects of supports 8.4 Role of modifiers 8.5 Role of preparation methods 8.6 Effects of process conditions 8.7 Role of precursor 8.8 Conclusions Acknowledgments References

9. Advances in the industrial applications of supercritical carbon dioxide

201 201 203 203 206 208 212 215 219 224 227 228 230 230

237

Jude A. Okolie, Sonil Nanda, Ajay K. Dalai and Janusz A. Kozinski 9.1 Introduction 9.2 Unique properties of SCCO2 9.3 Industrial applications of SCCO2 9.3.1 Extraction of bioactive compounds 9.3.2 Extraction of cannabinoids 9.3.3 Conversion of waste heat into power 9.3.4 Catalysis 9.3.5 Sustainable energy generation 9.3.6 Biomass pretreatment and recovery of value-added biochemicals 9.3.7 Other industrial applications 9.4 Conclusions and perspectives

237 238 240 240 242 243 244 245 246 247 250

Contents

Acknowledgments References

10. Application of membrane technology for CO2 capture and separation

ix 251 251

257

Wai Fen Yong, Can Zeng Liang and Chaitanyakumar Reddy Pocha Abbreviations List of symbols 10.1 Introduction 10.2 Transport mechanisms for gas separation 10.2.1 Diffusion in porous membranes 10.2.2 Diffusion in nonporous membranes 10.3 Membrane preparation 10.3.1 Preparation of polymeric membranes 10.3.2 Preparation of inorganic membranes 10.4 Polymeric membranes 10.4.1 Polymer blends membranes 10.4.2 Mixed matrix membranes 10.5 Inorganic membranes 10.5.1 Carbon molecular sieve membranes 10.5.2 Ceramic membranes 10.5.3 Zeolite membranes 10.6 Conclusions and perspectives References

11. Sequestration of carbon dioxide into petroleum reservoir for enhanced oil and gas recovery

257 258 259 260 261 262 264 264 267 269 269 273 274 274 276 279 281 282

291

Minhaj Uddin Monir, Azrina Abd Aziz, Fatema Khatun, Mostafa Tarek and Dai-Viet N. Vo Abbreviations 11.1 Introduction 11.2 Oil and gas reservoirs 11.3 Advanced oil and gas recovery mechanism 11.3.1 Enhanced oil recovery 11.3.2 Enhanced gas recovery 11.3.3 Challenges and strategy for increased oil/gas recovery 11.4 Fundamentals of CO2 gas injection 11.4.1 Sources of CO2 11.4.2 Surface facilities

291 291 293 295 296 297 297 297 298 301

x

Contents

11.5 Technologies for enhanced oil/gas recovery 11.5.1 CO2 injection for enhanced oil recovery 11.5.2 CO2 injection for enhanced gas recovery 11.5.3 CO2 solubility in oil and gas 11.5.4 CO2 injection facilities and process design considerations 11.6 Economic evaluation 11.7 Conclusions References Index

302 302 303 305 305 305 306 307 311

List of contributors Bawadi Abdullah Department of Chemical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak, Malaysia Zahra Alipour Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada May Ali Alsaffar Department of Chemical Engineering, University of Technology-Iraq, Baghdad, Iraq Bamidele Victor Ayodele Department of Chemical Engineering, Universiti Teknologi PETRONAS, Seri Iskandar, Perak, Malaysia Azrina Abd Aziz Faculty of Civil Engineering Technology, Universiti Malaysia Pahang, Kuantan, Pahang, Malaysia S. Toufigh Bararpour Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, Canada Nor Hafizah Berahim Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak, Malaysia Venu Babu Borugadda Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada Ajay K. Dalai Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada Ahmad Salam Farooqi Department of Chemical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak, Malaysia Shiva P. Gouda Department of Chemistry, College of Engineering and Technology, Bhubaneswar, Odisha, India Seyed Mojtaba Hashemi Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, Canada Davood Karami Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, Canada

xi

xii

List of contributors

Fatema Khatun Faculty of Civil Engineering Technology, Universiti Malaysia Pahang, Kuantan, Pahang, Malaysia Janusz A. Kozinski Faculty of Engineering, Lakehead University, Thunder Bay, Ontario, Canada Shamsul Rahman Mohamed Kutty Department of Civil and Environmental Engineering, Universiti Teknologi PETRONAS, Seri Iskandar, Perak Darul Ridzuan, Malaysia Siew Yoong Leong Department of Petrochemical Engineering, Universiti Tunku Abdul Rahman, Kampar, Perak Darul Ridzuan, Malaysia Qunliang Li School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi, China Can Zeng Liang Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore Nader Mahinpey Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, Canada Dinesh Kumar Mishra Department of Chemical Engineering/Research Institute of Industrial Science, Hanyang University, Seoul, Republic of Korea Pak Yan Moh Industrial Chemistry Programme, Faculty of Science and Natural Resources, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia Minhaj Uddin Monir Department of Petroleum and Mining Engineering, Jashore University of Science and Technology, Jashore, Bangladesh Siti Indati Mustapa Institute of Energy Policy and Research, National Energy University, Kajang Selangor, Malaysia Satyanarayan Naik Centre for Rural Development and Technology, Indian Institute of Technology Delhi, New Delhi, Delhi, India Sonil Nanda Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada Jude A. Okolie Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

List of contributors

xiii

Biswa R. Patra Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada Falguni Pattnaik Centre for Rural Development and Technology, Indian Institute of Technology Delhi, New Delhi, Delhi, India Chaitanyakumar Reddy Pocha School of Energy and Chemical Engineering, Xiamen University Malaysia, Selangor Darul Ehsan, Selangor, Malaysia Khairuddin Sanaullah Department of Chemical Engineering and Energy Sustainability, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia Mostafa Tarek Faculty of Chemical and Natural Resources Engineering, Universiti Malaysia Pahang, Kuantan, Pahang, Malaysia Cong Chien Truong Department of Bio-functional Molecular Engineering, University of Toyama, Toyama, Japan Dai-Viet N. Vo Center of Excellence for Green Energy and Environmental Nanomaterials, Nguyen Tat Thanh University, Ho Chi Minh City, Vietnam Hui Wang Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada Wai Fen Yong School of Energy and Chemical Engineering, Xiamen University Malaysia, Selangor Darul Ehsan, Selangor, Malaysia Mohammad Yusuf Department of Chemical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak, Malaysia Noor Asmawati Mohd Zabidi Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak, Malaysia

About the editors Dr. Sonil Nanda is a Research Associate at the University of Saskatchewan in Saskatoon, Saskatchewan, Canada. He received his PhD degree in biology from the York University, Canada; MSc degree in applied microbiology from the Vellore Institute of Technology (VIT University), India; and BSc degree in microbiology from the Orissa University of Agriculture and Technology, India. Dr. Nanda’s research areas include the production of advanced biofuels and biochemicals using thermochemical and biochemical conversion technologies such as gasification, pyrolysis, carbonization, torrefaction, and fermentation. He has gained expertise in hydrothermal gasification of various organic wastes and biomass, including agricultural and forestry residues, industrial effluents, municipal solid wastes, cattle manure, sewage sludge, food wastes, waste tires, and petroleum residues, to produce hydrogen fuel. His parallel interests include the generation of hydrothermal flames for the treatment of hazardous wastes, agronomic applications of biochar, phytoremediation of heavy metal contaminated soils, as well as carbon capture and sequestration. Dr. Nanda has published 15 books, 70 book chapters, and over 130 peer-reviewed journal articles. He is the editor of books entitled New Dimensions in Production and Utilization of Hydrogen (Elsevier), Recent Advancements in Biofuels and Bioenergy Utilization (Springer Nature), Biorefinery of Alternative Resources: Targeting Green Fuels and Platform Chemicals (Springer Nature), Fuel Processing and Energy Utilization (CRC Press), Bioprocessing of Biofuels (CRC Press), and Catalytic and Noncatalytic Upgrading of Oils (American Chemical Society), to name a few. Dr. Nanda serves as a fellow member of the Society for Applied Biotechnology in India, as well as a Life Member of the Indian Institute of Chemical Engineers, Association of Microbiologists of India, Indian Science Congress Association, and the Biotech Research Society of India. He is also an active member of several chemical engineering societies across North America such as the American Institute of Chemical Engineers, the Chemical Institute of Canada, the Combustion Institute-Canadian Section, and Engineers Without Borders Canada. Dr. Nanda is an assistant subject

xv

xvi

About the editors

editor for the International Journal of Hydrogen Energy (Elsevier) as well as an associate editor for the Environmental Chemistry Letters (Springer Nature) and Applied Nanoscience (Springer Nature). He has also edited several special issues in renowned journals such as the International Journal of Hydrogen Energy (Elsevier), Chemical Engineering Science (Elsevier), Biomass Conversion and Biorefinery (Springer Nature), Waste and Biomass Valorization (Springer Nature), Topics in Catalysis (Springer Nature), SN Applied Sciences (Springer Nature), and Chemical Engineering & Technology (Wiley).

About the editors

xvii

Dr. Dai-Viet N. Vo is the Director of the Center of Excellence for Green Energy and Environmental Nanomaterials at Nguyen Tat Thanh University in Ho Chi Minh City, Vietnam. He received his PhD degree in chemical engineering from the University of New South Wales in Sydney, Australia, in 2011. He has worked as a postdoctoral fellow at the University of New South Wales in Sydney and Texas A&M University in Qatar, Doha. Formerly, he was a senior lecturer at the Faculty of Chemical & Natural Resources Engineering in the Universiti Malaysia Pahang in Kuantan, Malaysia (2013
19). His research areas include the production of green synthetic fuels via Fischer
Tropsch synthesis using biomassderived syngas from various reforming processes. He is also an expert in advanced material synthesis and catalyst characterization. During the early days of his career, he worked as a principal investigator and coinvestigator for 21 different funded research projects related to sustainable and alternative energy. He has published 6 books, 20 book chapters, and more than 300 peer-reviewed journal articles and conference proceedings. He has served in the technical and publication committees of numerous international conferences in chemical engineering, catalysis, and renewable energy. Dr. Vo is the editor of books entitled New Dimensions in Production and Utilization of Hydrogen (Elsevier), Biorefinery of Alternative Resources: Targeting Green Fuels and Platform Chemicals (Springer Nature), and Fuel Processing and Energy Utilization (CRC Press). Dr. Vo is an assistant subject editor for the International Journal of Hydrogen Energy (Elsevier) and a guesteditor for several special issues in high-impact-factor journals such as the International Journal of Hydrogen Energy (Elsevier), Chemosphere (Elsevier), Comptes Rendus Chimie (Elsevier), Waste and Biomass Valorization (Springer), Topics in Catalysis (Springer), Journal of Chemical Technology & Biotechnology (Wiley), Chemical Engineering & Technology (Wiley), and several others. He is also an associate editor for the Environmental Chemistry Letters (Springer Nature) and Applied Nanoscience (Springer Nature). He is an editorial board member of many international journals, including SN Applied Sciences (Springer), Scientific Reports (Springer Nature), and PLoS One. Dr. Vo has been awarded as a Top Peer Reviewer 2019 powered by Publons.

xviii

About the editors

Dr. Van-Huy Nguyen received the BS degree (2008) in environmental engineering from the Ho Chi Minh City University of Technology, Vietnam, and an MS degree (2010) in chemical engineering from the National Taiwan University (NTU). He obtained his PhD degree in chemical engineering from the National Taiwan University of Science and Technology in 2015. He has gained the knowledge and experience of working in both academia and industry. Before joining Chettinad Academy of Research and Education as a Visiting Professor, he worked at Binh Duong University, Ton Duc Thang University, and Duy Tan University in Vietnam. Dr. Nguyen has published over 110 peerreviewed journal articles, 10 book chapters, and presented at many international conferences. Currently, he is the associate editor for the Applied Nanoscience (Springer Nature) and editorial board member of PLoS One. He is also the managing guest-editor and guest-editor of 10 special issues in journals of repute such as the Journal of Chemical Technology & Biotechnology (Wiley), Arabian Journal of Chemistry (Elsevier), Topics in Catalysis (Springer), Chemical Engineering Science (Elsevier), Biomass Conversion and Biorefinery (Springer), Materials Letters (Elsevier), Journal of Environmental Chemical Engineering (Elsevier), Sustainable Chemistry and Pharmacy (Elsevier), and Environmental Science and Pollution Research (Springer). He is an editor for edited books under production in Elsevier about photocatalysis, CO2 capture, and conversion. Dr. Nguyen is an active reviewer for many high-impact journals published by Elsevier, ACS, Wiley, Springer Nature, RSC, MDPI, and PLoS Publishers. His research works have gained broad interest through his highly cited research publications, book chapters, conference presentations, and workshop lectures. His research focuses on chemical and material aspects of (photo)catalytic processes and a basic understanding of (photo)catalysts, emphasizing the importance of clean energy in dealing with environmental problems, and production of value-added chemicals.

Preface Excessive utilization of fossil fuels and petrochemicals along with the increased industrial manufacturing processes, emissions from automobiles, and anthropogenic activities has resulted in a rise in the CO2 levels in the atmosphere. A higher level of CO2 in the atmosphere is a leading cause of global warming and climate change. Biofuels, biochemicals, and bioproducts have a lower carbon footprint because the CO2 liberated from their end-use is utilized during photosynthesis to produce new plant biomass. Nevertheless, there is a growing interest in carbon capturing and sequestration techniques along with their utilization for manufacturing value-added industrial products. This book covers the current research and development of some leading technologies for capturing and utilizing CO2 for high-value industrial processes and product manufacturing. Chapter 1 by Patra et al. gives an overview of several sources of CO2 generation along with some recent developments in CO2 capturing and storage technologies. The chapter also discusses the utilization of CO2 for producing value-added materials using various sustainable technologies. Chapter 2 by Ayodele et al. describes the prospects, challenges, and opportunities for sustainable utilization of CO2 towards a circular economy. Processes such as reforming hydrocarbons and biomass, as well as hydrogenation, are reported for the utilization of CO2 in producing renewable fuels and value-added products. Chapter 3 by Farooqi et al. comprehensively reviews the current progress and advancements of CO2 conversion into valuable fuels, including methane, dimethyl ether, methanol, and gasoline. Chapter 4 by Leong et al. discusses the opportunity and challenges in the bioconversion of carbon sources, which could provide promising and closed-loop solutions for food security, energy, resource scarcity, and reduction of CO2 emissions. Chapter 5 by Truong and Mishra gives a broad outline on the utility of homogeneous organic bases for the direct and smooth conversion of CO2 into urea, carbamates, carbonates, polymers, carboxylic acid derivatives, methanol, and heterocyclic compounds. Chapter 6 by Berahim and Zabidi highlights the progress made by the ongoing research and development in the catalytic conversion of CO2 into methanol with a focus on developing Cu/ZnO-based catalysts, catalyst activity, and the impact of process variables on the formation of products. Chapter 7 by Mahinpey et al. reviews the current xix

xx

Preface

progress made in the application of CaO-based sorbents in the calciumlooping process applied in post- and precombustion technologies. Chapter 8 by Alipour et al. describes the evaluation of various heterogeneous catalysts for the dry reforming process by utilizing CO2. The chapter discusses the effects of catalyst components, catalyst preparation methods, and the impact of reforming process conditions on the catalytic activity and coke deposition. Chapter 9 by Okolie et al. provides an overview of the unique properties of supercritical CO2 and its applications in industrial processes such as hydrotreating of biofuels, extraction of bioactive compounds, including cannabinoids, biomass pretreatment, sterilization of medical equipment, and conversion of waste heat into power. Chapter 10 by Yong et al. elucidates the fundamentals of gas transport through polymeric and inorganic membranes followed by membrane preparation strategies, modifications methods in polymeric and inorganic membranes as well as prospects of membrane separation for CO2 capture. Chapter 11 by Monir et al. presents a detailed study of the effectiveness of the application of enhanced oil and gas technology in an unconventional petroleum reservoir. This chapter evaluates the prospects and challenges of CO2 sequestration in oil and gas reservoirs for their enhanced recovery. We are grateful to all the authors for contributing their high-quality chapters toward the development of this book. We also express our sincere thanks to the staff and associates at Elsevier for their enthusiastic assistance and support in the preparation of this book. Our special thanks go to Susan Dennis (Publisher), Emerald Li (Editorial Project Manager), R. Vijay Bharath (Production Project Manager), Sujatha Thirugnana Sambandam (Publishing Services Manager) and Christian J. Bilbow (Cover Designer). Sonil Nanda Dai-Viet N. Vo Van-Huy Nguyen

CHAPTER 1

A brief overview of recent advancements in CO2 capture and valorization technologies Biswa R. Patra1, Shiva P. Gouda2, Falguni Pattnaik3, Sonil Nanda1, Ajay K. Dalai1 and Satyanarayan Naik3 1

Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada Department of Chemistry, College of Engineering and Technology, Bhubaneswar, Odisha, India 3 Centre for Rural Development and Technology, Indian Institute of Technology Delhi, New Delhi, Delhi, India 2

1.1 Introduction The rising human population, urbanization, and industrialization have led to environmental pollution, specifically carbon dioxide (CO2) emission. CO2 is the primary greenhouse gas that has emanated the deterioration of the climate and its concentration in the atmosphere endured an exponential growth from 284 ppm (1850) to 409 ppm (2018) (Patra et al., 2021). The major share of CO2 released to the atmosphere comes from fossil fuel combustion (Fig. 1.1). The global energy consumption is estimated to reach 815 quadrillion Btu in 2040 compared to 582 Btu in 2017 (Anwar et al., 2020; Patra et al., 2021). The global energy demand is mostly achieved by nonrenewable fossil fuels, which amplifies the emission of CO2 by causing a steep increase in greenhouse gas (GHG) level. Approximately 77% of the total GHG emission is shared by CO2 and removal of such an excessive amount from the atmosphere becomes unachievable through forests and oceans (Ellabban et al., 2014). Furthermore, other renewable alternatives to fossil fuels such as solar, wind, hydropower, and biofuels could limit CO2 emissions to some extent (Nanda et al., 2014; Okolie et al., 2021b). As a potential solution to mitigate carbon emissions, biofuels can be derived from renewable biomass through sustainable conversion technologies (Jha et al., 2022; Nanda et al., 2021; Pattnaik et al., 2022; Singh et al., 2021). Amid the increasing concern over anthropogenic CO2 emissions, the Intergovernmental Panel on Climate Change (IPCC) has launched a Carbon Dioxide Capture and Conversion DOI: https://doi.org/10.1016/B978-0-323-85585-3.00011-0

© 2022 Elsevier B.V. All rights reserved.

1

4

Carbon Dioxide Capture and Conversion

CO2 is released as an undesirable product in petrochemical processes, mainly when synthetic gas is used as an intermediate. The blast furnaces that are used for steel production use coal and coke as their primary fuels, while oil and gas are the primary fuels in the refining and chemical sectors. CO2 is also generated at the places where carbon is used as feedstock, a reducing agent for metal production, in calcination, and the fermentation of biomass. Coal is the dominant fuel in the power sector, accounting for 36% of global electricity in 2020. Eventually, during 2019
2020, there was a temporary decrease in the emissions of CO2 due to the COVID-19 related forced confinements in terms of reduced industrial manufacturing, mass transportation and aviation (Le Quéré et al., 2020). However, global coal use is anticipated to rebound in 2021 with global CO2 emissions of around 640 Mt (IEA, 2020). Among the developed countries and major emerging economy nations, China emitted 28% of global CO2 emissions in 2018 followed by the USA (15%), India (7%), Canada (2%), and Russia (5%) (IEA, 2020). Since emissions of CO2 is one of the major reasons for global climate change, the yearly exploding population growth from 6.2 billion in 2000 to 7.8 billion population in 2020 has not only increased rapid energy consumption rate but also posed tremendous environmental challenges along with the increase of CO2 emissions (Fig. 1.3) (Dong et al., 2018; Ribeiro et al., 2019).

1.3 CO2 capture and storage technologies As discussed in the abovementioned sections, CO2 is generated as one of the byproducts during the combustion of biomass and various fossil fuels in industrial or power plants. Separation of CO2 from industrial sources, compression, and delivery to a geologic location for storage or increased oil recovery are all parts of CCS (Raza et al., 2019). It has a wide range of industrial applications, including excellent CO2 mitigation from the process or exhaust gases, as well as natural gas (NG) processing. To capture CO2 from large point sources such as fossil fuel power plants, there are three major technical solutions such as post-combustion, pre-combustion, and oxy-combustion (oxy-fueling) (Kanniche et al., 2010). According to these technologies, CO2 is segregated from the H2 in pre-combustion, N2 in post-combustion, and from H2O in the oxy-fueling process, where the hydrocarbon fuels are combusted in the presence of O2. Moreover, in the

10

Carbon Dioxide Capture and Conversion

conversion of CO2 was studied by Song et al. (2016). The researchers used a copper nanoparticle/N-doped graphene electrode to achieve a higher selectivity of 84% for ethanol production and demonstrated the synergistic effect of Cu and carbon nanospikes interaction. Moreover, chemicals like ethane, ethylene, hydrocarbons, and oxygenates can also be produced by electrochemical activation of CO2 (Alper and Orhan, 2017). Falcinelli et al. (2017) developed an experimental protocol to produce methane after transforming CO2. The authors proposed an innovative and cost-effective method to react H2 with CO2 to produce methane. Perathoner and Centi (2014) stated that the petrochemical industry requires syngas, light olefins, hydrogen, and aromatics for chemical production. Therefore, switching to renewable hydrogen (produced from renewable sources) and utilizing CO2 as a carbon source by integrating it with biomass-derived platform molecules and lignin-derived aromatics production from lignin can result in the production of chemicals by restricting fossil fuels dependency completely. Perathoner and Centi (2014) showed the application of CO2 along with improvised FischerTropsch catalysts and hydrogen in producing light olefins. Barbato et al. (2013) studied the techno-economic aspect of CO2 reuse along with renewable H2 in producing methanol. According to the study, CO2-led methanol production is found to be economically competitive with a production cost of 300
350 per ton, which is on par with the current market cost. Martín and Grossmann (2017) studied the production of methanol from CO2. The researchers used an integrated facility to produce methanol from the gasification of lignocellulosic biomass (switchgrass) and utilized the captured CO2 resulting from the gasification to strengthen the methanol production by 50%. The required H2 for the methanol production was sourced from the electrolysis of water using solar, wind, and biogas energy. Furthermore, dimethyl ether (DME) can also be generated from methanol dehydration and can also be used as an alternative to diesel fuel (Okolie et al., 2021a,c). Apart from the cost perspective, the synthesis of methanol by utilizing CO2 will be effective in reducing GHG emissions. CO2 can be utilized for the commercial production of oil from depleted reservoirs. The CO2 enhanced oil recovery (CO2 EOR) is considered an effective technology for carbon sequestration, and CO2 injection into oil reservoirs along with water enhances the oil production by 15% (Dai et al., 2014). Secondly, CO2 can be utilized to produce clean

A brief overview of recent advancements in CO2 capture and valorization technologies

11

fuels and chemicals after undergoing carboxylation or reduction. Chemicals such as urea, methanol, salicylic acid, and carbonates (cyclic and poly) are the major chemical sources, which utilize approximately 130 MT of CO2 annually (Alper and Orhan, 2017). Urea being rich in nitrogen is widely used as a fertilizer in the manufacture of adhesives, plastics, resins, etc. Koohestanian et al. (2018) proposed a novel process technology to produce chemicals like urea and ammonia by utilizing captured CO2 from the flue gas stream. The designed process accounted for 14.9 MT of CO2 removal and production of 1.68 tons of urea per ton of CO2. The ever-increasing trend for photocatalytic conversion of CO2 propelled by solar energy is gaining notable attention. In this method, CO2 solar energy is photochemical reduction. It is being considered as the cleanest and effective technology to mitigate environmental issues without necessitating any extra energy consumption (Ma et al., 2017). The authors studied reliable, highly efficient earth-abundant catalysts for photocatalytic conversion of CO2 to value-added chemicals. The authors reported that activation of CO2 in the photocatalytic reaction has an immense role as a rate-determining step for the generation of different chemicals. Bioconversion routes are also considered an effective technology for the conversion of CO2 to valuable chemicals. The anaerobic digestion leads to the generation of CO2-rich biogas (with 40% CO2), making it unfit for heat and electricity application with lower calorific value (Fu et al., 2020). The upgrading of biogas to biomethane involves the elimination of CO2 or its conversion to CH4. In situ biogas upgrading, which involves CO2 conversion to CH4, is a promising method to augment its applicability as an energy source. Furthermore, such pathways include direct electron transfer (via electromethanogenic process), direct hydrogenotrophic methanogenesis (reduction of CO2 to CH4 using H2 as an electron donor), and indirect acetoclastic methanogenesis (conversion of CO2derived acetate to CH4) (Barbato et al., 2013; Can et al., 2014; Zhu et al., 2020; Sravan et al., 2020). Petrochemical industries are well known for polymer production. The copolymerization of CO2 has emerged as an effective method for the generation of aliphatic polycarbonates (Zhu, 2019). CO2-based polymers are considered as biodegradable and sustainable in nature, which have attracted the current market (Bhat et al., 2020). The coupling of CO2 and epoxides with metal catalysts leads to the generation of linear polycarbonates, while the functional polycarbonates can also be derived from CO2

12

Carbon Dioxide Capture and Conversion

by using direct copolymerization (involves a functional monomer) and post-polymerization functionalization (Wang and Darensbourg, 2018).

1.5 Conclusions The increase in greenhouse gas level has induced global warming with majority of CO2 present. The anthropogenic CO2 is generated from fuel combustion, electricity and heat production, transport, residential and industrial activities. The removal of CO2 can be done by natural ways, i.e., forests and oceans are not sufficient to ease the challenge. In addition, around 10% of this generated CO2 is being utilized and its efficient removal is now the topic of concern. CCUS has emerged as an effective technology in mitigating atmospheric CO2. Thus, the prominent carbon capture technologies such as post-combustion, pre-combustions, and oxycombustion strategies have fueled the wide utilization of CO2 in producing fuels such as biohydrogen and biomethane as well as chemicals such as methanol, dimethyl ether, salicylic acid, urea, carbonates, etc. CCUS is also a promising technology for biofuel production and an alternative to nonrenewable fossil fuels. It acts as a prominent pathway in improving environmental and economic contexts by generating massive employment opportunities.

Acknowledgments The authors would like to thank the Natural Sciences and Engineering Research Council (NSERC) of Canada and the Canada Research Chairs (CRC) program for funding this bioenergy research.

References Adams, D., Oh, D.H., Kim, D.W., Lee, C.H., Oh, M., 2020. Prediction of SOx
NOx emission from a coal-fired CFB power plant with machine learning: plant data learned by deep neural network and least square support vector machine. Journal of Cleaner Production 270, 122310. Alper, E., Orhan, O.Y., 2017. CO2 utilization: developments in conversion processes. Petroleum 3, 109
126. Anwar, M.N., Fayyaz, A., Sohail, N.F., Khokhar, M.F., Baqar, M., Yasar, A., et al., 2020. CO2 utilization: turning greenhouse gas into fuels and valuable products. Journal of Environmental Management 260, 110059. Araújo, O.D.Q.F., de Medeiros, J.L., 2017. Carbon capture and storage technologies: present scenario and drivers of innovation. Current Opinion in Chemical Engineering 17, 22
34.

A brief overview of recent advancements in CO2 capture and valorization technologies

13

Barbato, L., Iaquaniello, G., Mangiapane, A., 2013. Reuse of CO2 to make methanol using renewable hydrogen. In CO2: A Valuable Source of Carbon. Springer, London, pp. 67
79. Basile, A., Gugliuzza, A., Iulianelli, A., Morrone, P., 2011. Membrane technology for carbon dioxide (CO2) capture in power plants. In: Basile, A., Nunes, S.P. (Eds.), Advanced Membrane Science and Technology for Sustainable Energy and Environmental Applications. Woodhead Publishing, Cambridge, pp. 113
159. Bhat, G.A., Luo, M., Darensbourg, D.J., 2020. Catalysis of carbon dioxide and oxetanes to produce aliphatic polycarbonates. Green Chemistry 22, 7707
7724. Bui, M., Adjiman, C.S., Bardow, A., Anthony, E.J., Boston, A., Brown, S., et al., 2018. Carbon capture and storage (CCS): the way forward. Energy & Environmental Science 11 (5), 1062
1176. Can, M., Armstrong, F.A., Ragsdale, S.W., 2014. Structure, function, and mechanism of the nickel metalloenzymes, CO dehydrogenase, and acetyl-CoA synthase. Chemical Reviews 114 (8), 4149
4174. Carpenter, S.M., Long III, H.A., 2017. Integration of carbon capture in IGCC systems. In: Wang, T., Stigel, G. (Eds.), Integrated Gasification Combined Cycle (IGCC) Technologies. Woodhead Publishing, Cambridge, pp. 445
463. Chaubey, N., Singh, V.K., Quraishi, M.A., 2017. Electrochemical approach of Kalmegh leaf extract on the corrosion behavior of aluminium alloy in alkaline solution. International Journal of Industrial Chemistry 8 (1), 75
82. Chen, S.J., Zhu, M., Fu, Y., Huang, Y.X., Tao, Z.C., Li, W.L., 2017. Using 13X, LiX, and LiPdAgX zeolites for CO2 capture from post-combustion flue gas. Applied Energy 191, 87
98. Cong, W.J., Nanda, S., Li, H., Fang, Z., Dalai, A.K., Kozinski, J.A., 2021. Metal-organic framework-based functional catalytic materials for biodiesel production: a review. Green Chemistry 23, 2595
2618. Dai, Z., Middleton, R., Viswanathan, H., Fessenden-Rahn, J., Bauman, J., Pawar, R., et al., 2014. An integrated framework for optimizing CO2 sequestration and enhanced oil recovery. Environmental Science and Technology Letters 1 (1), 49
54. Dong, K., Hochman, G., Zhang, Y., Sun, R., Li, H., Liao, H., 2018. CO2 emissions, economic and population growth, and renewable energy: empirical evidence across regions. Energy Economics 75, 180
192. Ellabban, O., Abu-Rub, H., Blaabjerg, F., 2014. Renewable energy resources: current status, future prospects and their enabling technology. Renewable and Sustainable Energy Reviews 39, 748
764. Falcinelli, S., Capriccioli, A., Pirani, F., Vecchiocattivi, F., Stranges, S., Martì, C., et al., 2017. Methane production by CO2 hydrogenation reaction with and without solid phase catalysis. Fuel 209, 802
811. Fu, S., Angelidaki, I., Zhang, Y., 2020. In situ biogas upgrading by CO2-to-CH4 bioconversion. Trends in Biotechnology 39, 336
347. Furcas, F.E., Pragot, W., Chacartegui, R., Afzal, W., 2020. Sodium carbonate-based post combustion carbon capture utilising trona as main sorbent feed stock. Energy Conversion and Management 208, 112484. Ganesh, I., 2016. Electrochemical conversion of carbon dioxide into renewable fuel chemicals
The role of nanomaterials and the commercialization. Renewable and Sustainable Energy Reviews 59, 1269
1297. Hamm, J.B., Ambrosi, A., Griebeler, J.G., Marcilio, N.R., Tessaro, I.C., Pollo, L.D., 2017. Recent advances in the development of supported carbon membranes for gas separation. International Journal of Hydrogen Energy 42 (39), 24830
24845. He, R., Cong, S., Wang, J., Liu, J., Zhang, Y., 2019. Porous graphene oxide/porous organic polymer hybrid nanosheets functionalized mixed matrix membrane for efficient CO2 capture. ACS Applied Materials Interfaces 11 (4), 4338
4344.

14

Carbon Dioxide Capture and Conversion

Hüser, N., Schmitz, O., Kenig, E.Y., 2017. A comparative study of different amine-based solvents for CO2-capture using the rate-based approach. Chemical Engineering Science 157, 221
231. Hussain, A., Farrukh, S., Minhas, F.T., 2015. Two-stage membrane system for postcombustion CO2 capture application. Energy & Fuels: An American Chemical Society Journal 29 (10), 6664
6669. IEA 2020. Available from: https://www.iea.org/reports/co2-emissions-from-fuel-combustion-overview (Accessed on 23 April 2021). Jha, S., Okolie, J.A., Nanda, S., Dalai, A.K., 2022. A review of biomass resources and thermochemical conversion technologies. Chemical Engineering & Technology 45, 791
799. Kang, K., Papari, S., Bamdad, H., Nanda, S., Dalai, A.K., Berruti, F., 2021. Algae as a bioresource for clean fuels, carbon fixation and wastewater reclamation. In: Dalai, A. K., et al., (Eds.), Algal Biorefinery: Developments, Challenges and Opportunities. Routledge, Abingdon, United Kingdom, pp. 1
23. Kanniche, M., Gros-Bonnivard, R., Jaud, P., Valle-Marcos, J., Amann, J.M., Bouallou, C., 2010. Pre-combustion, post-combustion and oxy-combustion in thermal power plant for CO2 capture. Applied Thermal Engineering 30 (1), 53
62. ˇ ˇ Kárászová, M., Zach, B., Petrusová, Z., Cervenka, V., Bobák, M., Syc, M., et al., 2020. Post-combustion carbon capture by membrane separation, review. Separation and Purification Technology 238, 116448. Khan, Z., Ali, S., Umar, M., Kirikkaleli, D., Jiao, Z., 2020. Consumption-based carbon emissions and international trade in G7 countries: the role of environmental innovation and renewable energy. Science of the Total Environment 730, 138945. Koohestanian, E., Sadeghi, J., Mohebbi-Kalhori, D., Shahraki, F., Samimi, A., 2018. A novel process for CO2 capture from the flue gases to produce urea and ammonia. Energy 144, 279
285. Koytsoumpa, E.I., Bergins, C., Kakaras, E., 2018. The CO2 economy: review of CO2 capture and reuse technologies. The Journal of Supercritical Fluids 132, 3
16. Le Quéré, C., Jackson, R.B., Jones, M.W., Smith, A.J.P., Abernethy, S., Andrew, R.M., et al., 2020. Temporary reduction in daily global CO2 emissions during the COVID19 forced confinement. Nature Climate Change 10, 647
653. Ma, Y., Wang, Z., Xu, X., Wang, J., 2017. Review on porous nanomaterials for adsorption and photocatalytic conversion of CO2. Chinese Journal of Catalysis 38 (12), 1956
1969. Mac Dowell, N., Fennell, P.S., Shah, N., Maitland, G.C., 2017. The role of CO2 capture and utilization in mitigating climate change. Nature Climate Change 7 (4), 243
249. Martín, M., Grossmann, I.E., 2017. Towards zero CO2 emissions in the production of methanol from switchgrass. CO2 to methanol. Computers and Chemical Engineering 105, 308
316. Masson-Delmotte, V., Zhai, P., Pörtner, H.O., Roberts, D., Skea, J., Shukla, P.R., et al., 2018. Global warming of 1.5°C, 1. An IPCC Special Report on the Impacts of Global Warming, pp. 1
9. Mukherjee, A., Okolie, J.A., Abdelrasoul, A., Niu, C., Dalai, A.K., 2019. Review of post-combustion carbon dioxide capture technologies using activated carbon. Journal of Environmental Sciences 83, 46
63. Nanda, S., Dalai, A.K., Berruti, F., Kozinski, J.A., 2016a. Biochar as an exceptional bioresource for energy, agronomy, carbon sequestration, activated carbon and specialty materials. Waste and Biomass Valorization 7, 201
235. Nanda, S., Mohammad, J., Reddy, S.N., Kozinski, J.A., Dalai, A.K., 2014. Pathways of lignocellulosic biomass conversion to renewable fuels. Biomass Conversion and Biorefinery 4, 157
191.

A brief overview of recent advancements in CO2 capture and valorization technologies

15

Nanda, S., Okolie, J.A., Patel, R., Pattnaik, F., Fang, Z., Dalai, A.K., et al., 2021. Catalytic hydrothermal co-gasification of canola meal and low-density polyethylene using mixed metal oxides for hydrogen production. International Journal of Hydrogen Energy. Available from: https://doi.org/10.1016/j.ijhydene.2021.08.179. Nanda, S., Reddy, S.N., Mitra, S.K., Kozinski, J.A., 2016b. The progressive routes for carbon capture and sequestration. Energy Science & Engineering 4, 99
122. Nguyen, T.D., Tran, T.V., Singh, S., et al., 2020. Conversion of carbon dioxide into formaldehyde. In: Asiri, A.M., Eric, L. (Eds.), Conversion of Carbon Dioxide Into Hydrocarbons, Vol. 2. Springer Nature, Singapore, pp. 159
183. , Technology; Inamuddin. Okolie, J.A., Mukherjee, A., Nanda, S., Dalai, A.K., Kozinski, J.A., 2021a. Nextgeneration biofuels and platform biochemicals from lignocellulosic biomass. International Journal of Energy Research 45, 14145
14169. Okolie, J.A., Nanda, S., Dalai, A.K., Kozinski, J.A., 2021b. Chemistry and specialty industrial applications of lignocellulosic biomass. Waste and Biomass Valorization 12, 2145
2169. Okolie, J.A., Patra, B.R., Mukherjee, A., Nanda, S., Dalai, A.K., et al., 2021c. Futuristic applications of hydrogen in energy, biorefining, aerospace, pharmaceuticals and metallurgy. International Journal of Hydrogen Energy 46, 8885
8905. Patra, B.R., Mukherjee, A., Nanda, S., Dalai, A.K., 2021. Biochar production, activation and adsorptive applications: a review. Environmental Chemistry Letters 19, 2237
2259. Pattnaik, F., Patra, B.R., Okolie, J.A., Nanda, S., Dalai, A.K., Naik, S., 2022. A review of thermocatalytic conversion of biogenic wastes into crude biofuels and biochemical precursors. Fuel 320, 123857. Peng, Y., Zhao, B., Li, L., 2012. Advance in post-combustion CO2 capture with alkaline solution: a brief review. Energy Procedia 14, 1515
1522. Perathoner, S., Centi, G., 2014. CO2 recycling: a key strategy to introduce green energy in the chemical production chain. ChemSusChem 7 (5), 1274
1282. Prasanth, S.M., Kumar, P.S., Harish, S., Rishikesh, M., Nanda, S., Vo, D.V.N., 2021. Application of biomass derived products in mid-size automotive industries: a review. Chemosphere 280, 130723. Qazvini, O.T., Telfer, S.G., 2021. MUF-16: A robust metal
organic framework for preand post-combustion carbon dioxide capture. ACS Applied Materials Interfaces 13 (10), 12141
12148. Rana, R., Nanda, S., Kozinski, J.A., Dalai, A.K., 2018. Investigating the applicability of Athabasca bitumen as a feedstock for hydrogen production through catalytic supercritical water gasification. Journal of Environmental Chemical Engineering 6, 182
189. Rana, R., Nanda, S., Maclennan, A., Hu, Y., Kozinski, J.A., Dalai, A.K., 2019. Comparative evaluation for catalytic gasification of petroleum coke and asphaltene in subcritical and supercritical water. Journal of Energy Chemistry 31, 107
118. Rana, R., Nanda, S., Reddy, S.N., Dalai, A.K., Kozinski, J.A., Gökalp, I., 2020. Catalytic gasification of light and heavy gas oils in supercritical water. Journal of the Energy Institute 93, 2025
2032. Raza, A., Gholami, R., Rezaee, R., Rasouli, V., Rabiei, M., 2019. Significant aspects of carbon capture and storage
A review. Petroleum 5 (4), 335
340. Ribeiro, H.V., Rybski, D., Kropp, J.P., 2019. Effects of changing population or density on urban carbon dioxide emissions. Nature Communications 10 (1), 1
9. Saeed, I.M., Alaba, P., Mazari, S.A., Basirun, W.J., Lee, V.S., Sabzoi, N., 2018. Opportunities and challenges in the development of monoethanolamine and its blends for post-combustion CO2 capture. International Journal of Greenhouse Gas Control 79, 212
233.

16

Carbon Dioxide Capture and Conversion

Seo, K., Tsay, C., Hong, B., Edgar, T.F., Stadtherr, M.A., Baldea, M., 2020. Rate-based process optimization and sensitivity analysis for ionic-liquid-based post-combustion carbon capture. ACS Sustainable Chemistry Engineering 8 (27), 10242
10258. Siefert, N.S., Agarwal, S., Shi, F., Shi, W., Roth, E.A., Hopkinson, D., et al., 2016. Hydrophobic physical solvents for pre-combustion CO2 capture: experiments, computational simulations, and techno-economic analysis. International Journal of Greenhouse Gas Control 49, 364
371. Singh, A., Nanda, S., Guayaquil-Sosa, J.F., Berruti, F., 2021. Pyrolysis of Miscanthus and characterization of value-added bio-oil and biochar products. The Canadian Journal of Chemical Engineering 99, S55
S68. Snider, M.T., Verweij, H., 2014. Gas sorption studies on Zeolite Y membrane materials for post-combustion CO2 capture in coal-fired plants. Microporous and Mesoporous Materials 192, 3
7. Song, Y., Peng, R., Hensley, D.K., Bonnesen, P.V., Liang, L., Wu, Z., et al., 2016. High-selectivity electrochemical conversion of CO2 to ethanol using a copper nanoparticle/N-doped graphene electrode. ChemistrySelect 1, 6055
6061. Sravan, J.S., Sarkar, O., Mohan, S.V., 2020. Electron-regulated flux towards biogas upgradation
triggering catabolism for an augmented methanogenic activity. Sustainable Energy and Fuels 4 (2), 700
712. Tran, T.V., Nguyen, D.T.C., Nguyen, H.T.T., Nanda, S., Vo, D.V.N., Do, S.T., et al., 2019. Application of Fe-based metal-organic framework and its pyrolysis products for sulfonamide treatment. Environmental Science and Pollution Research 26, 28106
28126. Wang, Y., Darensbourg, D.J., 2018. Carbon dioxide-based functional polycarbonates: metal catalyzed copolymerization of CO2 and epoxides. Coordination Chemistry Reviews 372, 85
100. Wu, F., Argyle, M.D., Dellenback, P.A., Fan, M., 2018. Progress in O2 separation for oxy-fuel combustion
A promising way for cost-effective CO2 capture: a review. Progress in Energy and Combustion Science 67, 188
205. Ye, S., Jiang, X., Ruan, L.W., Liu, B., Wang, Y.M., Zhu, J.F., et al., 2013. Postcombustion CO2 capture with the HKUST-1 and MIL-101 (Cr) metal
organic frameworks: adsorption, separation and regeneration investigations. Microporous and Mesoporous Materials 179, 191
197. Younas, M., Rezakazemi, M., Daud, M., Wazir, M.B., Ahmad, S., Ullah, N., et al., 2020. Recent progress and remaining challenges in post-combustion CO2 capture using metal-organic frameworks (MOFs). Progress in Energy and Combustion Science 80, 100849. Zhang, Z., Pan, S.Y., Li, H., Cai, J., Olabi, A.G., Anthony, E.J., et al., 2020. Recent advances in carbon dioxide utilization. Renewable and Sustainable Energy Reviews 125, 109799. Zhu, Q., 2019. Developments on CO2-utilization technologies. Clean Energy 3, 85
100. Zhu, X., Chen, L., Chen, Y., Cao, Q., Liu, X., Li, D., 2020. Effect of H2 addition on the microbial community structure of a mesophilic anaerobic digestion system. Energy 198, 117368.

CHAPTER 2

Sustainable utilization of CO2 toward a circular economy: prospects, challenges, and opportunities Bamidele Victor Ayodele1, Siti Indati Mustapa2, May Ali Alsaffar3 and Dai-Viet N. Vo4 1

Department of Chemical Engineering, Universiti Teknologi PETRONAS, Seri Iskandar, Perak, Malaysia Institute of Energy Policy and Research, National Energy University, Kajang Selangor, Malaysia Department of Chemical Engineering, University of Technology-Iraq, Baghdad, Iraq 4 Center of Excellence for Green Energy and Environmental Nanomaterials, Nguyen Tat Thanh University, Ho Chi Minh City, Vietnam 2 3

2.1 Introduction The various anthropogenic activities have contributed immensely to the ever-increasing concentration of greenhouse gases in the atmosphere (Ayodele et al., 2017; Bölük and Mert, 2014; Fan et al., 2011). These greenhouse gases, which consist of methane, nitrous oxide, fluorinated gases, and carbon dioxide (CO2), are the main courses of greenhouse effects that invariably result in climate change (Anderson et al., 2016). Amongst the various greenhouse gas emissions, CO2 accounts for about 80% of the total concentration as indicated in Fig. 2.1 (Chastas et al., 2018), while the other greenhouse gases make up the remaining 20% (Chastas et al., 2018). The high concentration of CO2 emitted into the atmosphere could be attributed to several industrial processes using linear economic models (Liu and Bae, 2018; Nejat et al., 2015; Ozturk and Acaravci, 2010). In the past decades, industrial processes have been operated based on the linear economic model which involves the utilization of materials and energy resources in such a way that the safety of the environment is not in utmost consideration (Michelini et al., 2017). In the linear economic model, every stage of the product cycle starting from production, consumption, and disposal significantly contribute to CO2 emission (Sariatli, 2017).

Carbon Dioxide Capture and Conversion DOI: https://doi.org/10.1016/B978-0-323-85585-3.00001-8

© 2022 Elsevier B.V. All rights reserved.

17

Carbon Dioxide Capture and Conversion

Proportion of gas emitted (%)

18

80 70 60 50 40 30 20 10 0 Methane

Carbon dioxide

Nitrous oxide

Fluorinated gases

Figure 2.1 Proportion of greenhouse gases emitted into the atmosphere.

Building and Environment




The amount of CO2 emitted in the advanced economy has increased steadily in the past two decades as indicated in Fig. 2.2. This can be attributed to several industrial processes that are heavily reliant on the utilization of fossil fuels (Liu and Bae, 2018; Mahmood et al., 2020). On the other hand, in the rest of the world there is a sharp decline in the CO2 emissions from 2008 that can be attributed to the gradual introduction of renewable energy into the energy mix. A series of studies have linked economic growth, which is often link with rapid industrialization with significant CO2 emissions. Mahmood et al. (2020) investigated the relationship between industrialization, urbanization, and CO2 emission in Saudi Arabia. The study revealed that there is a link between industrialization and CO2 emissions, which is also consistent with that reported by Liu and Bae (2018) for China. This implies that there was a significant increase in CO2 emissions on the environment due to an increase in industrialization. Similarly, Wang et al. (2018) and Ahmad et al. (2020) reported that there is a nexus between urbanization, economic growth, energy consumption, and CO2 emissions in empirical studies using data from 170 countries and 30 Chinese provinces, respectively. With the advent of circular economic models that entail continuous utilization of resources to eliminate waste, the emissions of CO2 can be significantly reduced by sustainably utilizing the CO2 emitted to produce value-added

Sustainable utilization of CO2 toward a circular economy

CO2 emission (Gt)

25

Advanced economy

19

Rest of the world

20 15

10 5 0 1990

1995

2000

2005

2010

2015

2020

Figure 2.2 Global CO2 emissions trend in an advanced economy and the rest of the world (IEA, 2020). Global CO2 emissions in 2019

products that are environmentally sustainable. Although several opportunities exist for sustainable utilization of CO2 based on the circular economic model in the chemical and allied industrials, it is noteworthy that these opportunities are often faced with myriads of challenges. Liu et al. (2018) reported how greenhouse gases can be reduced in a plastic industry using the circular economy concept. The study revealed that the integration of the circular economy concept into the plastic production process significantly reduces greenhouse gas emissions as well as facilitates the reduction of post-consumer waste pollution. The focus of this chapter is to analyze various technological processes that utilize CO2 in their production process based on a circular economic concept to identify prospects opportunities, and challenges for the implementation of the circular economic model.

2.2 Overview of pathways for CO2 emissions Anthropogenic activities, mainly from the utilization of fossil fuels such as coal, oil, natural gas, as well as industrial and agricultural processes such as cement production, deforestation, account for a high concentration of CO2 emissions (Rahman et al., 2017). In addition, residential and commercial buildings also contribute significantly to CO2 emissions. As shown in Fig. 2.3, based on the report of the United States Environmental Protection Agency, the residential/commercial building, industrial,

20

Carbon Dioxide Capture and Conversion

35

CO2 emissions (%)

30 25 20 15 10 5 0 Residential and Commercial Building

Industry

Transportation

Figure 2.3 CO2 emissions from different sectors. gas emissions

Electricity

Other nonfossil fuel combustion

Greenhouse

transportation, electricity generation, and other non-fossil fuel combustion accounted for 11%, 15%, 35%, 31%, and 8% of CO2 emissions, respectively, in the United States for 2019 (EPA, 2021). Transportation and electricity generation accounted for 65% of the total CO2 emissions. A detailed description of the CO2 emissions in the various sector is presented in a subsequent section.

2.2.1 CO2 emissions in residential and commercial building According to the United Nations Environment Programme, the building sector accounted for 38% of the total CO2 emissions in 2019 representing 9.95 Gt CO2 (UNEP, 2020). The CO2 emissions from the building can be classified into either direct or indirect. The direct CO2 emissions entail the utilization of fossil fuel for energy consumption in buildings. Reports have shown that building and construction of building consumed over 36% of the total energy generated. Hence, serious concern has been raised on the need for policy formulation that will facilitate sustainable buildings and construction to mitigate the amount of CO2 contributed by the building sector. The indirect CO2 emissions from buildings arise from building material production activities which have also contributed 31% of CO2 emissions in the building sector.

Sustainable utilization of CO2 toward a circular economy

21

Huang et al. (2017) reported that the building material production and building energy uses in Xiamen, China contributed about 45% and 40% of the total CO2 emissions in the building sector. Based on the report of Heinonen et al. (2011), the building construction and infrastructure construction accounted for 131, 500 tons and 8500 tons of CO2 emissions in the Helsinki metropolitan area (HMA) of Finland. Ali et al. (2020) opined that the shortfall in sustainable urbanization, utilization of nonrenewable energy resources, and poorly designed building have held back the efforts in mitigating CO2 emissions in the building sectors. Hence, it is proposed that standards and policies that promote sustainability, smart building, circular economic concepts, low-carbon technology, and energy efficiency in the building be adopted as strategies to mitigate the huge amount of CO2 emitted from the building sector.

2.2.2 CO2 emissions in industrial processes Several industrial processes produce a huge amount of CO2 emissions through either fossil fuel consumption or noncombustion chemical reactions. Industrial processes involved in mining, chemical production, and metal production emit a huge amount of CO2 (Liu, 2016). In the mining industries, cement production, lime production, glass production, and other carbonaceous processes are responsible for huge emissions of CO2. Similarly, in the chemical industries, the production of ammonia, nitric acid, steam reforming of natural gas, and adipic acid production is responsible for a huge amount of CO2. As reported by Liu (2016), CO2 emissions from the production of alumina, plate glass, soda ash, ammonia, and calcium carbide in China cumulatively was 2.5 Gt during the period 1990
2013. Studies have also shown that the utilization of fossil fuel for various industrial processes accounted for about 16% of the total US CO2 emissions in 2019. The rapid growth in China’s cement production over the years has resulted in a significant increase in the amount of CO2 emissions (Gao et al., 2017). As indicated by Gao et al. (2017), there was a 1767% increase in the amount of CO2 emitted between 1980 and 2014. In the cement industry, the production of intermediate materials such as clinkers and other products is solely responsible for emissions of the bulk of the emitted CO2. Also, during calcination, the calcium carbonate obtained from limestone is thermally decomposed to form lime and CO2. Besides cement production, ammonia production also accounts for the huge amount of CO2 emissions from the industry.

22

Carbon Dioxide Capture and Conversion

CO2 could be directly or indirectly emitted during ammonia production. Natural gas is the main feedstock used for ammonia production; hence, for every metric ton of ammonia produced from natural gas, 2.6 tons of greenhouse gases (GHGs) that include CO2 are emitted (Liu et al., 2020). Besides natural gas, coal and other forms of fossil fuel could be used as feedstock for ammonia production to produce hydrogen (Twigg and Dupont, 2014). The feedstocks are thermo-catalytically converted to syngas, which consists of H2 and CO. In a water
gas shift reaction, CO reacts with water to produce more H2 together with the emissions of CO2. Studies have shown that over 420 million tons of CO2 are emitted annually by steam reforming of natural gas to produce hydrogen used for ammonia production (Liu et al., 2020). The utilization of electricity generated from fossil fuels to power ammonia production is responsible for the indirect CO2 emissions.

2.2.3 CO2 emissions in the transportation sector The transportation sector accounts for one-fifth of the global CO2 emissions (Hu et al., 2019). Most of the different categories of transportations such as passenger vehicles, marine, air, and rail make use of fossil fuels in their internal combustion engines to power mobility. The global CO2 emissions in the transportation sector as a function of the percentage of total fuel consumption has been on the rise from 1960 to 1987 when it experiences a sharp decline until 2000 as indicated in Fig. 2.4. The increase in the alternative means of transportations other than the internal combustion engines from 2003 contributed to the decline in CO2 emissions. A recent report in the European Union indicated that CO2 emissions from the transportation sector increased in 2018 and 2019 to about 1089 Mt CO2 equivalent which is projected to be 1097 Mt CO2 equivalent in 2030 (European Environment Agency, 2018). The road transportation sector was reported to have the highest CO2 contribution followed by aviation and shipping. Li et al. (2016) reported that the transportation section in China accounts for 10% of the total CO2 emissions.

2.2.4 CO2 emissions electricity generation Studies have shown that economic growth, industrialization, and energy utilization are directly linked (Dong et al., 2018; Mardani et al., 2019). Industrialization that is largely dependent on sustainable energy drives economic growth (Wu et al., 2018). Most of the global electricity

Sustainable utilization of CO2 toward a circular economy

23

22 21 20 19 18 17

1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014

CO2 emissions from transport (% of total fuel combustion)

23

Figure 2.4 Trend in global CO2 emissions of transportation from 1960 to 2014 (The World Bank, 2020). Global CO2 emission trend

generations are primarily dependent on coal, natural, and petroleum, which has been one of the main sources of CO2 emissions (Kåberger, 2018). Over 40% of global electricity generation is obtained from the coal power plant, which is responsible for the highest CO2 emission per kWh of electricity generated (Nejat et al., 2015). As a result of this, there is a growing preference to substitute coal with natural gas as the source of fuel for electricity generation. This reported a sharp decline in global coal demand by 1.5% in 2019 compared to the increase in global natural gas demand. The US EPA reported in 2019 that electricity generation from fossil sources accounted for 31% of the total CO2 emissions in the United States. The bulk of US electricity (about 62%) is generated using fossil fuels such as coal, natural gas, and petroleum (EPA, 2021). The utilization of these fossil fuels for electricity generation cumulatively accounted for over 99% of the total CO2 emissions in the United States in 2019 (EIA, 2021). As shown in Fig. 2.5, the amount of CO2 emitted during electricity generation is strongly dependent on the type of fossil fuel used. Fig. 2.4 shows that 952 million metric tons of CO2 were emitted from the generation of 947,891 million kWh electricity using coal. On the other hand, 560 million metric tons of CO2 were emitted from generating 1,358,047 million kWh electricity using natural gas. The generation of 15,471 million of electricity from petroleum resulted in the least CO2 emissions of 15 million metric tons.

Carbon Dioxide Capture and Conversion

Electricity generation (kWh)

24

1,400,000 1,200,000 1,000,000 800,000 600,000 400,000 200,000 0

Electricity generation million kWh CO2 emissions million metric tons

Coal

Natural gas

Petroleum

947,891

1,358,047

15,471

952

560

15

Axis Title

Figure 2.5 Electricity generation from different fuel sources in the United States and resulting CO2 emission. Annual Energy Outlook 2021

2.3 Strategies and circular economic model for mitigation of CO2 emissions and its sustainable utilization Climate changes caused by greenhouse effects of the emitted greenhouses into the environment often result in serious disruption of economics and human lives. This necessitated the urgent action through the Paris Agreement embraced by several countries in 2015 for a serious commitment to tackling climate change (Liu et al., 2018). Recently, the United Nations Secretary-General has proposed six climate-positive actions for governments of different countries in the post-COVID-19 economic recovery. Some of the one action tailored toward reduction of CO2 emissions include green transition to accelerate investment for decarbonization of all aspects of the economy and investment in sustainable solutions as well as confronting all climate risks. In the subsequent section, strategies to reduce CO2 emissions and the sustainable utilization of emitted CO2 within the concept of circular economy are presented.

2.3.1 Strategies for CO2 emission reduction Series of strategies that include energy efficiency, fuel switching, carbon capture, and sequestration, improved land use, and land use policies as well as energy conservation have been proposed as efficient means of reducing CO2 emissions as shown in Fig. 2.6.

Sustainable utilization of CO2 toward a circular economy

25

Energy efficiency

Energy conservation

Improved land use and land use practices

CO2 emissions reduction strategies

Fuel switching

Carbon capture and Sequestration

Figure 2.6 Strategies to reduce CO2 emissions from different processes.

Since the building sector is one of the highest contributors to CO2 emissions, appropriate energy efficiency strategies in building and building construction could help to mitigate CO2 emissions. Noailly (2012) investigated the influence of unconventional environmental policy instruments on technological innovations that could improve energy efficiency in buildings. Using an empirical analysis, the author evaluated the effect of policy instruments such as regulatory energy standards in buildings codes, energy prices, and specific government energy research and development expenditures as well different technological innovations on the energy efficiency of buildings in seven European countries between 1989 and 2004. Wu and Skye (2018) reported that innovations in residential net-zero energy buildings can substantially reduce energy consumption and CO2 emissions. Moreover, advanced building design and technological innovations such as improved building envelope designs, efficient heating, ventilation, and air conditioning (HVAC) systems, household hot water systems, and integration of phase change materials also play a vital role in significantly reducing CO2 emissions in the building. Rieser et al. (2021) reiterated that the integration of energy-efficient ventilation systems was reported to significantly improve building efficiency. In addition to energy efficiency, energy conservation through energy saving by engaging in personal behavioral patterns that tend to reduce energy utilization could also reduce CO2 emissions. Besides energy-efficient buildings, energy efficiency in transportation can significantly mitigate CO2 emissions.

26

Carbon Dioxide Capture and Conversion

Akbar et al. (2020) empirically evaluated the transport energy efficiency in 19 countries. Energy efficiency in transportation can be implemented in form of system efficiency, travel efficiency, and vehicle efficiency. System efficiency entails the utilization of land, social and economic activities in a manner that there is limited use of transportation thereby reducing fuel consumption. The travel efficiency strategy involves the use of public transportation as well as a nonmotorized mode of transportation rather than using personal vehicles to reduce CO2 emissions per kilometer traveled (Bielas, 2021). On the other hand, vehicle efficiency strategy requires the use of the minimum amount of energy per kilometer traveled. This can be achieved using technological innovations that optimized fuel consumption. Fuel switching is also one of the strategies to reduce CO2 emissions. Fuel switching is a situation whereby an end-use energy source is replaced with another to meet defined specifications. Fuel switching can be applied to enhance building efficiency by replacing home heating systems that make use of natural gas with a heat pump that make use of all-electric air source. Wilson and Staffell (2018) reported that effective carbon pricing, right incentives, and political will could rapidly facilitate fuel switching from coal to natural gas, thereby reducing CO2 emissions. The adaptation of the fuel-switching strategy could help to reduce CO2 emissions in marine transportation. Abadie et al. (2017) reported the strategy to reduce CO2 emissions in the shipping industry using the fuel-switching concept. The existing fleet in the shipping industries investigated was placed under strict regulations to use low-sulfur marine diesel in place of conventional diesel. Similarly, the environmental challenges of the utilization of coal-fired industrial boilers have been reportedly reduced using a fuel-switching strategy. Han et al. (2017) performed a techno-economic analysis of fuel-switching strategy in a coal-fired industrial boiler. The study revealed that switching the fuel source from coal to other alternative fuels such as natural gas results in the reduction of pollutants emissions. Employing more renewable sources and the utilization of fuel with low carbon could significantly reduce carbon emissions. For industrial processes that utilized fossil fuels, a huge amount of CO2 is emitted (Liu and Bae, 2018). Carbon capture and sequestration have been proposed as an effective strategy to reduce carbon in such industrial processes (Tcvetkov et al., 2019). The carbon capture and sequestration strategy is the process whereby the CO2 is captured from the plant, and

Sustainable utilization of CO2 toward a circular economy

27

transported through a pipeline to a point it can be used or injected in an abandoned oil well for storage purposes (Rahman et al., 2017). The capture and sequestration of CO2 as a renewable energy source for sustainable utilization has been reported by Rahman et al. (2017). The authors proposed that the integration of carbon capture and sequestration and biofuel production whereby the CO2 will serve as feedstock could provide an opportunity for sustainable development.

2.4 Processes for sustainable utilization of CO2 for valueadded products CO2 emitted from various processes shown in Fig. 2.7 can be sustainably utilized or converted to value-added products. Some of these value-added products can serve as alternative fuels that can be switch with the existing fossil fuel. The CO2 emitted can be directly used for enhanced oil recovery as supercritical CO2, geothermal fluid, and other industrial processes. In addition, the CO2 can be used as feedstocks for several industrial processes involved in biochemical, photochemical, thermochemical, and electrochemical conversion processes. Some of the techniques that have been investigated for converting CO2 to renewable fuel and chemicals include

Figure 2.7 Sustainable utilization of CO2 based on the circular economy concept.

28

Carbon Dioxide Capture and Conversion

catalytic reforming and hydrogenation processes (Han et al., 2016; Witoon et al., 2021).

2.4.1 CO2 reforming of hydrocarbon and biomass In the thermochemial reforming process, CO2 is employed as cofeedstock for reforming hydrocarbons such as natural gas and biomass as shown in Fig. 2.8 (Roslan et al., 2020). In the CO2 reforming of hydrocarbons, synthesis gas (a mixture of carbon monoxide and hydrogen) is produced. Several studies have reported that the CO2 reforming reaction has great potential as a technological pathway to mitigate CO2 emissions. The syngas produced from the reforming of the hydrocarbons (e.g., natural gas, coal, and oil) and biomass serve as important intermediates for Fischer-Tropsch synthesis, methanol production, oxo-synthesis, and water
gas shift reaction (Kirsch et al., 2020). These processes are performed using thermochemical, photochemical, biochemical, and electrochemical. The thermochemical routes involve the use of thermal energy at a temperature range of 700°C
1000°C for the conversion of CO2containing feedstocks in the presence of a catalyst. The thermochemical CO2 conversion is constrained by challenges with high thermal energy requirement which is often supplied from energy generated from fossil

Figure 2.8 Thermochemical CO2 reforming of hydrocarbon and biomass to syngas.

Sustainable utilization of CO2 toward a circular economy

29

sources, and catalyst deactivation from sintering and carbon deposition. The energy constraints can be overcome by using abundant energy from solar resources. Several authors have reported the potential of employing solar energy for CO2 reforming of hydrocarbons. Han et al. (2017) reported solar energy application for CO2 reforming of methane. The study revealed that high H2 and CO yields of 129 and 370 mmol/gcat/h, respectively, were obtained over the Pt/black TiO2 photocatalyst. Tahir et al. (2018) investigated photo-induced CO2 reforming of methane to renewable fuel over La-TiO2 photocatalysts in a continuous flow photoreactor. The study revealed that the photocatalytic CO2 reforming of methane was efficient for the production of syngas suitable as feedstock for Fischer-Tropsch synthesis of renewable fuels. Pan et al. (2020) reported the CO2 reforming of methane in an integrated photocatalytic and thermo-catalytic process using Zn-doped Pt/CeO2 catalyst. The study revealed that the photoillumination of the CO2 reforming reaction help to improve the stability of the thermo-catalytic process, thereby overcoming the challenges of catalyst deactivation. The solar-powered photothermochemical catalysis process could be a promising route for the sustainable utilization of CO2. The synergistic benefits of integrating photocatalytic and thermocatalytic conversion of glycerol and CO2 over Au/ZnWO4-ZnO catalysts have been investigated by Liu et al. (2019). The authors concluded that excellent photocatalytic performance in converting both the glycerol and CO2 to glycerol carbonate, an important intermediate for the production of valuable chemicals, can be attributed to the strong visible light absorption capacity of the catalysts as well as the effective separation of the photogenerated electron-hole pairs.

2.4.2 CO2 hydrogenation to renewable fuels and value-added products Hydrogenation is one of the strategies to chemically convert CO2 into valuable chemical products and renewable energy sources such as lower olefins, hydrocarbons, formic acids, methanol, and alcohols using hydrogen and catalysts (Liu et al., 2019). As shown in Fig. 2.9, myriads of products can be formed through catalytic CO2 hydrogenation which often posed the challenges of dispersed product distribution. Higher alcohols obtained from CO2 hydrogenation can be used for producing biofuel which can be blended or use in place of diesel. Studies have shown that the combustion of biofuel reduces emissions and improved engine

30

Carbon Dioxide Capture and Conversion

Figure 2.9 Hydrogenation of CO2 to various renewable fuel and various value-added products.

efficiency. Additionally, the methanol obtained from the CO2 hydrogenation process has a wide application. It can be used as intermediate feedstocks for producing chemicals such as chloromethane, acetic acid, and formaldehyde, which are important components of polymer production. Methanol can be directly used as fuel or blend with gasoline to reduce NOx and CO2 emissions. The catalytic hydrogenation of CO2 to different products has been widely investigated. Witoon et al. (2021) reported that Co-Zn/K-Al2O3 and Fe-Co/KAl2O3 catalysts were highly active in CO2 hydrogenation to light olefins. Light olefins are mainly used for producing polyethylene, which is commonly used for plastic processing and packaging. The direct hydrogenation of CO2 to methanol over Pd/ZnO catalysts has been reported by Bahruji et al. (2016). The study revealed that the formation of Pd-Zn alloy help to minimize the formation of CO by the reverse water
gas shift reaction. In thermochemical CO2 hydrogenation, high energy is required to activate the reaction. The constraint of the high energy required can be reduced by using the electrochemical and photochemical activation process which required mild reaction conditions. The electrochemical CO2 hydrogenation over hybrid ZnO/g-C3N4 nanoelectrodes was reported by Mulik et al. (2021). The study shows that the formate obtained from the electrochemical CO2 hydrogenation over hybrid ZnO/g-C3N4 is a result of series of intermediate reactions based on the reaction mechanism. Bimetallic palladium-copper hydride catalysts have been employed for the CO2 hydrogenation to formate and formic

Sustainable utilization of CO2 toward a circular economy

31

acid Liu et al. (2020). The synergistic interaction between the catalysts and the reactants resulted in the formation of the PdCuCO2H4 complex, which is an intermediate for the formation of formate and formic acid. The application of the photochemical process for CO2 hydrogenation has the advantage of using abundant solar resources and minimizing CO2 emissions from the utilization of energy from fossil sources. The photocatalytic CO2 hydrogenation to CH4 under visible light has been reported by Tahir et al. (2020). The study revealed that the 2D/2D Mt loaded mCN composite photocatalysts were efficient in the hydrogenation reaction whereby the hydrogen was oxidized, and the CO2 was reduced to CH4 in the presence of excessive H /e-pairs. Zhang et al. (2019) employed monolithic Pd-embedded g-C3N4/reduced graphene oxide aerogel for photocatalytic CO2 reduction to CH4. The photocatalysts were highly efficient in the CO2 hydrogenation to CH4 at a rate of 6.4 μmol/g/h.

2.5 Overcoming the challenges of CO2 valorization to sustainable products The various technological pathways for CO2 transformation to sustainable products are promising but are constraint by various challenges such as high product distribution, high thermal energy requirement, catalyst deactivation, inadequate conversion, product selectivity, complex kinetics, and thermodynamics (Roy et al., 2018). Technological innovations, as well as advances in research and development in designing and synthesis of highly efficient catalysts with high selectivity, have been proposed as some of the solutions to the myriads of challenges. Besides, the integration of the various reactor configurations to enhance product distributions and facilitate high conversion rates of the CO2 has been reported to be a key strategy. To prevent a situation whereby the activation of the CO2 in the various valorization processes is reliant on the energy derived from fossil sources, the solar power system can be integrated to tap from the abundant solar energy resources. The application of robust optimization strategies can be applied to optimize the catalytic design and synthesis as well as the reaction conditions to obtain the desired selectivity, maximum conversion, and yield. The application of response surface methodology for the optimization of CO2 hydrogenation to methanol has been reported by Borisut and Nuchitprasittichai (2019). The objective of this optimization strategy was to minimize the methanol production cost per tons of methanol produced. The study revealed

32

Carbon Dioxide Capture and Conversion

that a minimum production cost of $565.54 per ton of methanol produced was obtained at optimized conditions. Optimization of synthesis conditions for CO2 hydrogenation to light olefins has been investigated by Numpilai et al. (2019). Synthesis conditions such as mass ratios of Ln2O3 to SAPO-34 as well as the operating conditions including temperature, pressure, and space velocity on the production of light olefins from the CO2 hydrogenation were evaluated. At optimized conditions of Ln2O3 to SAPO-34 ratio of 2:1, the temperature of 360°C, pressure of 25 bar, and space velocity of 1500 mL/gcat/h, the maximum yield of 7.3% was obtained for the olefins. The optimization of the Si/Al ratio for improved activity in CO2 hydrogenation to CH4 over Ni/Zeolites catalysts has been investigated by Bacariza et al. (2018). The study revealed that a lower affinity of the zeolites to water was obtained at a higher Si/Al ratio, thereby improving its property.

2.6 Conclusions The prospects and opportunities of sustainable utilization of CO2 emitted from the various anthropogenic activities have been presented in this chapter. Extensive research reported in the literature shows that there are several promising technological routes for the sustainable utilization of CO2. Amongst the various valorization routes, catalytic CO2 reforming of hydrocarbon and biomass, as well as catalytic CO2 hydrogenation, offer great potentials to produce chains of values-added products that can be employed directly as renewable fuels and chemical precursors that can be used as building blocks for the production of different chemicals. The various studies in the literature have reported thermochemical, photochemical, and electrochemical CO2 valorization reactions with each of the processes have their merits and demerits. Whereas the thermochemical process is associated with high reactant conversions, and product yields, it is constrained with high energy demand and catalyst deactivation. Taking advantage of the abundant solar resources and highly efficient photocatalysts, the challenges of high thermal requirement and catalyst deactivation in the thermochemical process can be overcome using solar energy and photocatalysts. Using appropriate optimization strategies, the operating conditions of each of the processes can be optimized to obtain the most effective conditions. The renewable fuel produced can be used as source fuel to generate energy that can be used to run the thermochemical process based on the circular economy concept.

Sustainable utilization of CO2 toward a circular economy

33

References Abadie, L.M., Goicoechea, N., Galarraga, I., 2017. Adapting the shipping sector to stricter emissions regulations: fuel switching or installing a scrubber? Transportation Research Part D: Transport and Environment 57, 237
250. Agarwal, A.S., Rode, E., Sridhar, N., Hill, D., 2017. Conversion of CO2 to Value-Added Chemicals: Opportunities and Challenges. Handbook of Climate Change Mitigation and Adaptation. Springer, pp. 2
33. Ahmad, F., Draz, M.U., Ozturk, I., Su, L., Rauf, A., 2020. Looking for asymmetries and nonlinearities: the nexus between renewable energy and environmental degradation in the Northwestern provinces of China. Journal of Cleaner Production 266, 121714. Akbar, U., Popp, J., Khan, H., Khan, M.A., Oláh, J., 2020. Energy efficiency in transportation along with the belt and road countries. Energies 13, 2607. Ali, K.A., Ahmad, M.I., Yusup, Y., 2020. Issues, impacts, and mitigations of carbon dioxide emissions in the building sector. Sustainability 2020, 7427. Anderson, T.R., Hawkins, E., Jones, P.D., 2016. CO2, the greenhouse effect and global warming : from the pioneering work of Arrhenius and Callendar to today’s Earth System Models. Endeavour 40, 178
187. Ayodele, B.V., Khan, M.R., Cheng, C.K., 2017. Greenhouse gases mitigation by CO2 reforming of methane to hydrogen-rich syngas using praseodymium oxide supported cobalt catalyst. Clean Technologies and Environmental Policy 19, 795
807. Bacariza, M.C., Graça, I., Lopes, J.M., Henriques, C., 2018. Enhanced activity of CO2 hydrogenation to CH4 over Ni based zeolites through the optimization of the Si/Al ratio. Microporous and Mesoporous Materials 267, 9
19. Bahruji, H., Bowker, M., Hutchings, G., Dimitratos, N., Wells, P., Gibson, E., et al., 2016. Pd/ZnO catalysts for direct CO2 hydrogenation to methanol. Journal of Catalysis 343, 133
146. Bielas, M., 2021. Smart City Transportation and Energy Efficiency. Smart City Transportation and Energy Efficiency Take. Available from: https://www.iotforall.com/energy-efficient-cities-transportation-systems/. Bölük, G., Mert, M., 2014. Fossil and renewable energy consumption, GHGs (greenhouse gases) and economic growth: evidence from a panel of EU (European Union) countries. Energy 74, 439
446. Borisut, P., Nuchitprasittichai, A., 2019. Methanol production via CO2 hydrogenation: sensitivity analysis and simulation—based optimization. Frontiers in Energy Research 7, 81. Chastas, P., Theodosiou, T., Kontoleon, K.J., Bikas, D., 2018. Normalising and assessing carbon emissions in the building sector: a review on the embodied CO2 emissions of residential buildings. Building and Environment 130, 212
226. Dong, K., Hochman, G., Zhang, Y., Sun, R., Li, H., Liao, H., 2018. CO2 emissions, economic and population growth, and renewable energy: empirical evidence across regions. Energy Economics 75, 180
192. EIA, 2021. Annual Energy Outlook 2021. EPA, 2021. Greenhouse gas emissions. United States Environmental Protection Agency. European Environment Agency, 2018. Emissions of air pollutants from transport. In Indicator Assessment. Fan, M.S., Abdullah, A.Z., Bhatia, S., 2011. Utilization of greenhouse gases through dry reforming: screening of nickel-based bimetallic catalysts and kinetic studies. ChemSusChem 4, 1643
1653. Gao, T., Shen, L., Shen, M., Liu, L., Chen, F., Gao, L., 2017. Evolution and projection of CO2 emissions for China’s cement industry from 1980 to 2020. Renewable and Sustainable Energy Reviews 74, 522
537.

34

Carbon Dioxide Capture and Conversion

Han, B., Wei, W., Chang, L., Cheng, P., Hu, Y.H., 2016. Efficient visible light photocatalytic CO2 reforming of CH4. ACS Catalysis 6, 494
497. Han, Y., Shen, B., Zhang, T., 2017. A techno-economic assessment of fuel switching options of addressing environmental challenges of coal-fired industrial boilers: an analytical work for China. Energy Procedia 142, 3083
3087. Heinonen, J., Säynäjoki, A., Junnila, S., 2011. A longitudinal study on the carbon emissions of a new residential development. Sustainability 3, 1170
1189. Hu, J., Wood, R., Tukker, A., Boonman, H., de Boer, B., 2019. Global transport emissions in the Swedish carbon footprint. Journal of Cleaner Production 226, 210
220. Huang, W., Li, F., Cui, S.H., Huang, L., Lin, J.Y., 2017. Carbon footprint and carbon emission reduction of urban buildings: a case in Xiamen City, China. Procedia Engineering 198, 1007
1017. IEA, 2020. Global CO2 emissions in 2019. In International Energy Agency. Available from: https://www.iea.org/articles/global-co2-emissions-in-2019. Kåberger, T., 2018. Progress of renewable electricity replacing fossil fuels. Global Energy Interconnection 1, 48
52. Kirsch, H., Sommer, U., Pfeifer, P., Dittmeyer, R., 2020. Power-to-fuel conversion based on reverse water-gas-shift, fischer-tropsch synthesis and hydrocracking: mathematical modeling and simulation in Matlab/Simulink. Chemical Engineering Science 227, 115930. Li, W., Li, H., Zhang, H., Shuang, S., 2016. The analysis of CO2 emissions and reduction potential in China’s transport sector. Mathematical Problems in Engineering 2016, 1043717. Liu, Z., 2016. National carbon emissions from the industry process: production of glass, soda ash, ammonia, calcium carbide and alumina. Applied Energy 166, 239
244. Liu, X., Bae, J., 2018. Urbanization and industrialization impact of CO2 emissions in China. Journal of Cleaner Production 172, 178
186. Liu, Z., Adams, M., Cote, R.P., Chen, Q., Wu, R., Wen, Z., et al., 2018. How does circular economy respond to greenhouse gas emissions reduction: an analysis of Chinese plastic recycling industries. Renewable and Sustainable Energy Reviews 91, 1162
1169. Liu, J., Li, Y., Liu, H., He, D., 2019. Photo-thermal synergistically catalytic conversion of glycerol and carbon dioxide to glycerol carbonate over Au/ZnWO4-ZnO catalysts. Applied Catalysis B: Environmental 244, 836
843. Liu, X., Elgowainy, A., Wang, M., 2020. Life cycle energy use and greenhouse gas emissions of ammonia production from renewable resources and industrial by-products. Green Chemistry 22 (17), 5751
5761. Mahmood, H., Alkhateeb, T.T.Y., Furqan, M., 2020. Industrialization, urbanization and CO2 emissions in Saudi Arabia: asymmetry analysis. Energy Reports 6, 1553
1560. Mardani, A., Streimikiene, D., Cavallaro, F., Loganathan, N., Khoshnoudi, M., 2019. Carbon dioxide (CO2) emissions and economic growth: a systematic review of two decades of research from 1995 to 2017. Science of the Total Environment 649, 31
49. Michelini, G., Moraes, R.N., Cunha, R.N., Costa, J.M.H., Ometto, A.R., 2017. From linear to circular economy: PSS conducting the transition. Procedia CIRP 64, 2
6. Mulik, B.B., Bankar, B.D., Munde, A.V., Chavan, P.P., Biradar, A.V., Sathe, B.R., 2021. Electrocatalytic and catalytic CO2 hydrogenation on ZnO/g-C3N4 hybrid nanoelectrodes. Applied Surface Science 538, 148120. Nejat, P., Jomehzadeh, F., Taheri, M.M., Gohari, M., Muhd, M.Z., 2015. A global review of energy consumption, CO2 emissions and policy in the residential sector (with an overview of the top ten CO2 emitting countries). Renewable and Sustainable Energy Reviews 43, 843
862.

Sustainable utilization of CO2 toward a circular economy

35

Noailly, J., 2012. Improving the energy efficiency of buildings: the impact of environmental policy on technological innovation. Energy Economics 34, 795
806. Numpilai, T., Wattanakit, C., Chareonpanich, M., Limtrakul, J., Witoon, T., 2019. Optimization of synthesis condition for CO2 hydrogenation to light olefins over In2O3 admixed with SAPO-34. Energy Conversion and Management 180, 511
523. Ozturk, I., Acaravci, A., 2010. CO2 emissions, energy consumption and economic growth in Turkey. Renewable and Sustainable Energy Reviews 14, 3220
3225. Pan, F., Xiang, X., Du, Z., Sarnello, E., Li, T., Li, Y., 2020. Integrating photocatalysis and thermocatalysis to enable efficient CO2 reforming of methane on Pt supported CeO2 with Zn doping and atomic layer deposited MgO overcoating. Applied Catalysis B: Environmental 260, 118189. Rahman, F.A., Aziz, M.M.A., Saidur, R., Bakar, W.A.W.A., Hainin, M.R., Putrajaya, R., et al., 2017. Pollution to solution: capture and sequestration of carbon dioxide (CO2) and its utilization as a renewable energy source for a sustainable future. Renewable and Sustainable Energy Reviews 71, 112
126. Rieser, A., Pfluger, R., Troi, A., Herrera-Avellanosa, D., Thomsen, K.E., Rose, J., et al., 2021. Integration of energy-efficient ventilation systems in historic buildings—review and proposal of a systematic intervention approach. Sustainability 13, 2325. Roslan, N.A., Abidin, S.Z., Ideris, A., Vo, D.V.N., 2020. A review on glycerol reforming processes over Ni-based catalyst for hydrogen and syngas productions. International Journal of Hydrogen Energy 45, 18466
18489. Roy, S., Cherevotan, A., Peter, S.C., 2018. Thermochemical CO2 hydrogenation to single carbon products: scientific and technological challenges. ACS Energy Letters 3, 1938
1966. Sariatli, F., 2017. Linear economy vs circular economy: a comparative and analyzer study for optimization of economy for sustainability. Visegrad Journal on Bioeconomy and Sustainable Development 6, 31
34. Tahir, B., Tahir, M., Amin, N.A.S., 2018. Tailoring performance of La-modified TiO2 nanocatalyst for continuous photocatalytic CO2 reforming of CH4 to fuels in the presence of H2O. Energy Conversion and Management 159, 284
298. Tahir, B., Tahir, M., Che Yunus, M.A., Mohamed, A.R., Siraj, M., Fatehmulla, A., 2020. 2D/2D Mt/m-CN composite with enriched interface charge transfer for boosting photocatalytic CO2 hydrogenation by H2 to CH4 under visible light. Applied Surface Science 520, 146296. Tcvetkov, P., Cherepovitsyn, A., Fedoseev, S., 2019. The changing role of CO2 in the transition to a circular economy: review of carbon sequestration projects. Sustainability 11, 5834. The World Bank, 2020. Global CO2 emission trend. The World Bank. Available from: https://data.worldbank.org/indicator/SP.POP0.65UP.TO. Twigg, M.V., Dupont, V., 2014. Hydrogen production from fossil fuel and biomass feedstocks. Advances in hydrogen production, storage and distribution. Woodhead Publishing Limited. UNEP, 2020. Building sector emissions hit record high, but low-carbon pandemic recovery can help transform sector
UN report. UN Environment Programme. Wang, S., Li, G., Fang, C., 2018. Urbanization, economic growth, energy consumption, and CO2 emissions: empirical evidence from countries with different income levels. Renewable and Sustainable Energy Reviews 81, 2144
2159. Wilson, I.A.G., Staffell, I., 2018. Rapid fuel switching from coal to natural gas through effective carbon pricing. Nature Energy 3, 365
372. Witoon, T., Chaipraditgul, N., Numpilai, T., Lapkeatseree, V., Ayodele, B.V., Cheng, C. K., et al., 2021. Highly active Fe-Co-Zn/K-Al2O3 catalysts for CO2 hydrogenation to light olefins. Chemical Engineering Science 233, 116428.

36

Carbon Dioxide Capture and Conversion

Wu, W., Skye, H.M., 2018. Net-zero nation: HVAC and PV systems for residential netzero energy buildings across the United States. Energy Conversion and Management 177, 605
628. Wu, Y., Zhu, Q., Zhu, B., 2018. Comparisons of decoupling trends of global economic growth and energy consumption between developed and developing countries. Energy Policy 116, 30
38. Zhang, R., Huang, Z., Li, C., Zuo, Y., Zhou, Y., 2019. Monolithic g-C3N4/reduced graphene oxide aerogel with in situ embedding of Pd nanoparticles for hydrogenation of CO2 to CH4. Applied Surface Science 475, 953
960.

CHAPTER 3

CO2 conversion technologies for clean fuels production Ahmad Salam Farooqi1, Mohammad Yusuf1, Noor Asmawati Mohd Zabidi2, Khairuddin Sanaullah3 and Bawadi Abdullah1 1 Department of Chemical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak, Malaysia Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak, Malaysia 3 Department of Chemical Engineering and Energy Sustainability, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia 2

3.1 Introduction Among significant greenhouse gases (GHGs), carbon dioxide (CO2) attains the leading position that contributes adversely to the global environment. Thus, it is vital to transform CO2 into a useful product through an effective method for the mitigation of GHG emissions. Recently, extensive research has been undertaken, involving capturing, storing, and utilization of CO2. The global energy sources mainly emanate from the burning of fossil fuels, which includes natural gas, oil, and coal. As reported in the International Energy Outlook Report of 2017, total energy consumption has risen from 575 quadrillions to 736 quadrillions between 2015 and 2017, an increase of around 28% (Invernizzi and Iora, 2016). It is reported that the highest CO2 emissions occur in the Asian countries, with China and India are the largest contributors. Also, the top 10 contributors to the CO2 emissions in the world are China, Korea, Canada, the United States, Germany, Iran, India, Japan, Russia, and Saudi Arabia. Contribution from these countries is nearly equal to 65% of the global CO2 emissions (IEA, 2006). Thus, one of the alternative ways to control emitted CO2 from continuously polluting the environment is by converting it into valuable products. The transformation of CO2 into valued materials receives huge attention as the atmospheric CO2 concentrations today has risen at an industrial level by 30%, which is from 280 ppm to 400 ppm (Ganesh, 2014). Ratification of the Kyoto Protocol involving several nations and governmental bodies at the United Nations Framework Convention on Climate Change is considered one of the crucial measures aiming to reduce CO2 emissions (Bode and Jung, Carbon Dioxide Capture and Conversion DOI: https://doi.org/10.1016/B978-0-323-85585-3.00006-7

© 2022 Elsevier B.V. All rights reserved.

37

38

Carbon Dioxide Capture and Conversion

2006; Gupta et al., 2003). The following three schemes have become significant to limit the CO2 emissions: (1) lessening energy consumptions, (2) alter what humans consume, and (3) shift humans’ stance for the resources and waste. The first two approaches can become sustainable in decreasing GHG emissions due to the progress in technologies such as wind, solar, biomass, and others (IEA, 2006), which have proved significant owing to having higher probable efficiency. The benefits of those industrial technologies that bear prospective consumption of CO2 as a raw material for fuel and chemical manufacturing (Jang et al., 2016) are expressed as follows: 1. CO2 can become a zero cost or even profit for raw material. 2. CO2 capture and sequestration technologies hold a favorable public view for businesses since, due to the growing public anxiety on curbing CO2 emissions, CO2 can thus be consumed for the formation of useful and environmentally friendly goods. 3. Besides paying for unused storage of CO2 as well as its transport expenses, CO2 should better be reprocessed to save these expenses. 4. Companies can have access to additional market shares due to the production of new chemicals/materials from CO2 conversion. 5. CCU provides openings to generate organic chemicals harmlessly because pollutants form because of several organic syntheses. The present potential routes involve the utilization of CO2 for the formation of several valued materials and fuels including methanol, gasoline, syngas, and others. The methods along with reactions that occurred in all these routes depend mainly on the characteristics of the catalysts used, which indicate the vitality of the research conducted on the development of the robust catalysts at an industrial scale. Therefore, the conversion of CO2 must gain more considerable interest due to the vast fuel market and there should be tremendous efforts and monetary interest in converting the CO2 emissions into energy. Thus, this chapter comprehensively reviews the current progress and advancements of CO2 conversion into valuable green fuels.

3.2 Methods for CO2 conversion Initial investigations on the CO2 conversion involving the CO2 reforming of methane reaction simply form synthesis gas (Liao and Horng, 2017; Muraza and Galadima, 2015). This chapter provides details regarding methane formation and liquid fuel production from a

CO2 conversion technologies for clean fuels production

39

transformation of CO2. However, the emerging technologies for CO2 conversions into green fuels are mainly based on methanol, gasoline, methane, dimethyl ether, and syngas production. Hydrogenation of CO2 (methanation reaction) is an encouraging technique to get rid of CO2 and use it as a value-added product fuel, i.e., methane. Direct CO2 conversion to gasoline seems to be a promising way of utilizing atmospheric GHG and, at the same time, producing a commercial fuel, which is the demand in the present scenario. Since the produced fuel (gasoline) can be used in the automobile sector without engine modifications, investing money in technological change in the automobile sector could be saved. Methanol is considered one of the primary petrochemical liquid, especially in the energy and chemical industries. Massive efforts have been devoted to transforming CO2 into methanol. This method is a considerably useful and attractive approach in terms of CO2 utilization although it will be technically competent with the present methanol industry. As compared to the other feedstocks, CH4 is an ideal feedstock owing to its abundance in nature, not requiring any further purification process from sulfur and other impurities, as well as having the most substantial heat of combustion and the highest C/H ratio.

3.3 CO2 conversion into methanol The main raw material for methanol formation is a synthesis gas of syngas, which contains a mixture of CO and H2. The process set-up includes three fundamental steps: preparation of syngas, methanol formation, and methanol purification. Although the potential resource base and potential rewards are enormous, the process involved is still considered a big issue to deal with. The process of breakdown and synthesis of the natural gas, coal, and biomass into methanol are not only costly in terms of technology development but mostly, they have adverse impacts on the environment. The mining, processing, and burning of the raw material itself release more CO2 to the environment. That is why direct conversion of CO2, coming from waste particularly, has been suggested as the most probable method to overcome both environmental and energy issues. However, CO2 fixation is a great challenge to deal with owing to its thermodynamically stable property, C O bonds. To break the double bonds, the presence of a highly active and selective catalyst is needed as it

40

Carbon Dioxide Capture and Conversion

can help to overcome the high-energy barrier that exists in the chemical reaction (Huang et al., 2015). With the recent advances in technology, including CO2 capture and storage, the idea of synthesizing methanol via a direct CO2 hydrogenation process also holds great potential. Not only it decreases the dependency on fossil fuel usage, but the opportunity that it offers in mitigating the greenhouse effect is also very attractive. Interestingly, the process safety involving CO2 handling is not an issue as it is categorized as a noncorrosive, nontoxic, and nonflammable gas. The process itself can also be applied in the existing syngas conversion plants without the need to adhere to any significant changes (Jadhav et al., 2014). Even so, the need to accommodate a cost-effective and sustainable production of H2 is still considered a major challenge (Raudaskoski et al., 2009). The water electrolysis process is an old technology that had been developed over centuries to produce H2. However, the process itself has its limitation (Raudaskoski et al., 2009; Waugh, 1992). It requires a lot of electrons to split the water molecules and in return, the cost of electricity or energy used is also high. Nevertheless, there is one demonstration plant being constructed under Carbon Recycling International Inc. in Iceland, where conversion of CO2 to methanol and the availability of H2 rely on geothermal energy. The plant has been managed to produce 2 million liters of methanol in a year. On the other hand, Mitsui Chemicals Inc also has declared its launch of a demonstration plant whereby the CO2 will be reduced using H2 coming from renewable solar energy (Ganesh, 2014). Although methanol can be formed by hydrogenating CO2, the reaction is supplemented with a reverse water
gas shift (RWGS) reaction as presented by Wambach et al. (1999), which can be expressed as follows: Methanol formation:
 CO2 3H2 CH3 OH H2 O ΔH298K 49:5 kJ=mol (3.1) Reverse water
gas shift reaction: CO2

H2

CO


H2 O ΔH298K

 41:2 kJ=mol

(3.2)

BASF built the industrial production plant in 1923 to produce methanol from syngas. The catalyst used in this plant was zinc oxide/chromium oxide with operating conditions of 300°C and 20.3 MPa, supporting high-pressure methanol synthesis. Cu and Zn were formed as the major components of the bulk of the catalysts used for CO2 transformation into the methanol, whereas the range of modifiers, including Al, B, Zr, Ga, Si, Cr, Ce, V, Ti, and others (Arena et al., 2007; Liaw and Chen, 2001;

CO2 conversion technologies for clean fuels production

41

Nitta et al., 1994; Saito and Murata, 2004), made up the part of the process. However, several improvements were suggested to the early methanol synthesis methods and Cu-based catalysts were selected for the lowpressure processes ( 100 atm) (Raudaskoski et al., 2009). Copper is still a significant catalyst component, especially in methanol synthesis because not only it is considered as an inexpensive metal, but it is also usually understood that the activation, chemisorption, and coordination of CO and the homogeneous parting of H2 occur on Cu or Cu° (Lee and Lee, 1995). Hydrogenation of CO2 normally occurs by employing a ternary Cu-Zn-Al oxide catalyst at a pressure ranging from 5 MPa to 10 MPa and temperature ranging from 473 K to 523 K. This reaction was initially established for CO hydrogenation. Nevertheless, the catalyst did not prove sufficiently active to hydrogenate pure CO2 (Bowker et al., 1988; Liu et al., 2007; Weigel et al., 1996). The intended mechanism of the reaction with a bifunctional catalyst comprising Cu and ZrO2 can be seen in Fig. 3.1. Table 3.1 shows the summary of the researchers working on the catalyst being developed to generate methanol from CO2 by hydrogenation reaction. Recently, a synergistic effect, particularly of Cu and ZnO, has been discussed although the definite role of ZnO is still ambiguous and yet to be fully understood. Concerning the role of ZnO, researchers had summarized the synergistic effect of Cu particles with ZnO into three distinct occurrences: 1. The altered structure of Cu particles via the wetting and nonwetting effect of Cu/ZnO system (Beinik et al., 2015). 2. The formation of Cu-Zn alloy being as the new active sites through the relocation of ZnOx species on the surface of Cu particles, which leads to the increase in the activity of the Cu surface (Tursunov et al., 2017).

Figure 3.1 Reaction pathway for methanol production with Cu/ZrO2 bifunctional catalyst.


Table 3.1 Previous studies on the catalyst for hydrogenation of CO2 into methanol. Catalyst

Method

Feed gas (CO2/H2)

CO2 conversion (%)

Type of reactor

Remarks

Reference

Cu/ZnO/Al2O3

Impregnation

1/3

14.0

• Temperature: 270°C • Pressure: 5 MPa

Tursunov et al. (2017)

Cu/ZnOSiO2

Impregnation

1/3

6.0

• Temperature: 270°C • Pressure: 5 MPa

Tursunov et al. (2017)

Cu/ZnO/SBA-15

Impregnation

1/3

14.2

Ca/Pd/SBA-15

Impregnation

1/3

4.0

• • • •

Temperature: 250°C Pressure: 2.25 MPa Temperature: 250°C Pressure: 4 MPa

Tasfy et al. (2015) Koizumi et al. (2012)

Ca/Pd/MCM-41

Impregnation

1/3

5.0

• Temperature: 250°C • Pressure: 4 MPa

Koizumi et al. (2012)

37.5PdCuZn/SiC

Impregnation

1/9




Cu/ZnO/Zr/Al2O3

Co-precipitation

1/3

23.20

• • • •

Temperature: 200°C Pressure: 1 MPa Temperature: 230°C Pressure: 3 MPa

Díez-Ramírez et al. (2017) Słoczy´nski et al. (2003)

0.8 Nb/Cu/ZnO

Co-precipitation

1/3

9.0

Fixed-bed continuous flow reactor Fixed-bed continuous flow reactor Fixed-bed reactor High-pressure fixed bed reactor High-pressure fixed bed reactor Tubular quartz reactor High-pressure fixed bed reactor Slurry reactor

• Temperature: 180°C • Pressure: 3 MPa

Din et al. (2016)

CO2 conversion technologies for clean fuels production

43

3. Hydrogen dissociation from ZnO to Cu, which acts as a source of hydrogen storage (Spencer, 1999). Apart from Cu and ZnO, other metals have been reported to be excellent in acting as the reactive sites favoring CO2 hydrogenation reaction to form methanol. Yin et al. (2018) found that the confinement of subnanometric Pd particles in the zeolitic imidazolate framework (ZIF-8) by addition of Zn and the respective catalyst resulted in a considerably high methanol yield as 0.65 g/gcath. The formation of PdZn alloy enhanced methanol yield by producing small-sized particles and plentiful defects due to the surface oxygen on ZnO. Incorporating Pt nanoparticles as the main catalyst active sites also achieved high CO2 conversion and methanol selectivity. Men et al. (2019) found 37% CO2 conversion and 62.6% methanol selectivity at atmospheric pressure and low temperature (30°C) mainly because of the highly dispersed Pt nanoparticles spread onto thin film. Pt nanoparticles coupled with In2O3 onto thin film were suggested to enhance CO2 capacity for adsorption, thus increasing the methanol activity. There is also a great deal of work being conducted involving ionic liquid as a precursor to transforming CO2 using catalytic hydrogenation into methanol. Han et al. (2019) worked on molybdenum carbide being dispersed on nitrogen and sulfur co-doped carbon as a catalyst, which resulted in 90.5% methanol selectivity and 0.405 gMeOH/gcath spacetime yield. High CO2 conversion at 16% was possible under optimal conditions. The catalyst does not suffer a deactivation phase within 100 h on stream using a fixed bed reactor. On the other hand, Geng et al. (2017) prepared N,P,S-co-doped C@nano-Mo2C (N, P, S-dC@Mo2C) catalyst by using protic ionic liquid involving N-butylimidazolium molybdophosphate and N-butylimidazolium p-toluenesulfate as a carbon source. However, the catalyst displayed high methanol selectivity at 91% and CO2 conversion of 19%. The respective catalyst also proved high stability in 100 h on stream reaction.

3.4 CO2 conversion into synthesis gas The combination of H2 and CO, also known as syngas, is a valuable outcome of gas reforming, which can be used to produce many chemicals with the corresponding H2 to Co ratios (SR), as seen in Fig. 3.2. The formation of syngas occurs through the conventional and efficient method of reforming natural gas (i.e., methane reforming). There are three prominent methods to reform the methane: dry reforming of

44

Carbon Dioxide Capture and Conversion

Figure 3.2 Applications of syngas based on its syngas ratio (SR) (Balasubramanian et al., 2018).


methane (DRM), steam reforming of methane (SRM), and partial oxidation of methane (POM) (Yusuf et al., 2021). Steam reforming of methane
 CH4 H2 O CO 3H2 ΔH298K 228 kJ=mol (3.3) Partial oxidation of methane CH4

1=2O2

CO

Dry reforming of methane CH4

CO2

2CO


2H2 ΔH298K
2H2 ΔH298K

 22:6 kJ=mol

247 kJ=mol

(3.4) 

(3.5)

Given the chemical utilization of CO2, DRM is the most attractive and useful. In addition, DRM is a promising method to generate syngas

CO2 conversion technologies for clean fuels production

45

because the end product is a hygienic and environmentally friendly fuel, which is made naturally from biomass anaerobic degradation, involving CO2 and CH4 (Xu et al., 2009). Furthermore, the syngas is obtained from DRM, which has a value of unity for the H2/CO ratio. This is desirable to produce long-chain hydrocarbon in Fischer-Tropsch synthesis and synthesis of oxygenated chemicals (Nieva et al., 2014). DRM is the major reaction (Eq. 3.5), whereas several side reactions may occur, including methane decomposition (MD) (Eq. 3.6), Boudouard reaction (BR) (Eq. 3.7), and RWGS reaction (Eq. 3.2) during the process. Methane decomposition
 2CO CO2 C ΔH298K 171 kJ=mol (3.6) Boudouard reaction CH4

2H2


C ΔH298K

75 kJ=mol



(3.7)

The endothermic reaction of DRM involves high temperatures to observe the sufficient conversions of the reactants (Baktash et al., 2015). It operates at a temperature ranging from 900 to 1273 K with a pressure of 1 bar to achieve the production of syngas because of the high equilibrium conversion of reactants. These temperature
pressure ranges help in minimizing the main thermodynamic impetuses, which boost the coke formation and decrease the catalyst stability (Farooqi et al., 2022). The selection of suitable catalysts for DRM is significant to prevent coke formation along with the sintering of the catalysts. Ni-based catalysts have proven to be favorable candidates because of their high activity and low cost compared to other noble metals, including Rh, Pd, Ir, and Pt (Zhang et al., 2015b). The performance of Ni-based catalysts diminishes due to the coke formation and catalyst sintering, which can be overwhelmed by the application of alkaline/alkaline earth metals to the active metal catalyst. The catalytic enhancements owing to the increased oxygen storage capacity, stable structure, and better reducibility were reported in the earlier studies (Jang et al., 2019). Zhang et al. (2020) investigated on the Ni catalyst being coated on zirconia and doped with rare earth metals, including Ce, La, Sm, and Y for DRM. The metal catalyst was tested that confirmed for the promoted catalysts to have storage capacity for the surface oxygen, which was proved useful to enhance CO2 activation and CH4 dissociation. Furthermore, it was determined that the sequence of the promoter’s activity was as follows: Y Sm La Ce.

46

Carbon Dioxide Capture and Conversion

Al-Swai et al. (2019) studied the metal-support interface involving bimetallic support (CeO2-MgO) and Ni metal. By making changes in the composition of the catalyst support, they found the influence on the conversions for CO2 and CH4 due to the fixed quantity of the metal (i.e., 10% Ni). It was confirmed that 15% CeO2 MgO was found to obtain 95.2% and 93.7% conversions for CH4 and CO2, respectively. The activity of the catalyst was enhanced owing to the greater ratio of Ce3 to Ce4 , which facilitated the generation of oxygen voids as well as additional sites of active Ni. Sokolov et al. (2012) worked on DRM at low reaction temperatures (i.e., 400°C) and synthesized a great deal of catalysts supports, including Al2O3, MgO, TiO2, SiO2, ZrO2, and La2O3-ZrO2. They examined the influence of different supports on Ni metal catalyst and determined that Ni on mixed oxide support (La2O3-ZrO2) was found to display the maximum stability for a duration of over 180 reaction hours. The reason has been better durability because of better harbor owing to the mixed metal oxide support to Ni ions. In addition, Zhang et al. (2015a) worked on a range of supports for Ni-based catalysts and found out that SiO2, TiO2, and ZrO2 proved to have a weak interaction with Ni, which led to deactivation of the catalyst. On the other hand, alumina and magnesia were found of strong interaction with Ni and hence formed a stable solid solution, which was both active and durable for a longer duration. It is well known that a strong interface between metal and support acquires a vital stance in the overall performance of a catalyst (Al
Swai, 2021). Table 3.2 displays DRM reaction using Ni-based catalyst at different temperatures, type of reactors, reactant conversions, product yield, and the rate of coke formation.

3.5 CO2 conversion to methane (methanation) reaction The use of oxides of carbon has been used as feedstock for hydrocarbon synthesis for over a century. Hydrogenation of CO2 to liberate methane (CH4) and water by Sabatier reaction was studied in 1902, followed by Fischer-Tropsch synthesis in 1920 (Barbarossa et al., 2014). Hydrogenation of CO2 into CH4 is a general topic of interest, especially in the last two decades. Catalytic reduction of CO2 is an encouraging technique to convert renowned GHG (i.e., mainly CO2) into fuel (i.e., CH4) in an economically feasible manner (Brito and Zanoni, 2017; Din et al., 2018). As per the inorganic theory of petroleum formation,

Table 3.2 Previous studies on catalysts for DRM (dry reforming of methane). Catalyst

Temperature (K)

Reactor type

CO2 conversion (%)

CH4 conversion (%)

Coke (gC/ (gcat/h))

Reference

15% Ni-MgO

1073

90.5

92.7




Min et al. (2015)

10% Ni/Al2O3ZrO2-CeO2 Ni-Co/Al2O3MgO-ZrO2 20% Ni/Al2O3ZrO2 Ni0.36-Al0.32Mg0.32 8% Ni/Al2O3ZrO2/0.5% K 14% Ni/0.5% KAl2O3 1.2% Ni-1.8% Co/Ce-Zr 10% Ni/Al2O3

1073

Fixed bed Inconel reactor Quartz fixed bed reactor U-shaped fixed-bed quartz reactor Continuous-flowmicroreactor Tabular fixed-bed reactor Fixed bed tabular quartz reactor Fixed bed flow reactor Tabular quartz reactor

92.2

80.1

0.00014

Li et al. (2011)

95

95




91.9

82.9

0.0007

95

95




Li and Wang (2004) Nagaraja et al. (2011) Alipour et al. (2014) Nagaraja et al. (2011) Castro Luna and Iriarte (2008) Djinovi´c et al. (2015) Selvarajah et al. (2016)

873
1173 1073 1023 1023 1023 1023 973

Stainless steel fixed bed reactor

90

90




86.6

81.3




84

78

0.24

60

50




48

Carbon Dioxide Capture and Conversion

hydrogenation of CO2 even took place by a serpentinite mechanism to convert the available CO2 into hydrocarbon in high-temperature water through the heat of molten magma (Etiope and Lollar, 2013). However, in the present scenario, the main area of focus in the hydrogenation of methane is the development of efficient catalysts and achieving higher selective conversions of CO2 (Zhong et al., 2019). Several catalysts, including both noble and nonnoble metals, were tested for this reaction to study the selectivity of CO2 to methane. Amongst the noble metals, Rh, Pd, Ru, and Pt were studied, whereas Co, Cu, and Ni amongst active metals have been used extensively for hydrogenation reaction (Wang et al., 2011). Marinoiu et al. (2015) conducted a study for Ni-based catalysts in the hydrogenation of CO2. They synthesized Ni catalyst supported on alumina and silica by impregnation method by Ni loadings varying from 12% to 22%. The reaction was performed in a continuous tubular flow reactor as shown in Fig. 3.3. It was concluded that Ni supported on alumina and silica show a significant selectivity of 99.8% at 1 atm and 400°C. Additionally, various parameters such as gas hourly space velocity, regeneration temperature, reaction temperature, and H2/CO2 ratios have been optimized. The recent studies focus on the photocatalytic reduction of CO2 due to its promising advantage of consuming sunlight as an energy source for the reaction. Recently, Sastre et al. (2014) used Ni supported on alumina-silica

Figure 3.3 A schematic diagram of the hydrogenation of CO2.

CO2 conversion technologies for clean fuels production

49

and NiO as a catalyst and solar irradiations as an energy source. They found and concluded that Ni supported on alumina and silica was superior to NiO catalyst. It gave CO2 conversion of over 90% and a selectivity of around 95% in the photocatalytic reactor with outstanding reproducibility even after 6 h. They even studied the reaction mechanism as shown in Fig. 3.4. In another study, a novel photocatalyst was generated and studied by Gui et al. (2014). They synthesized a multi-walled carbon nanotube (MWCNT) on titania (TiO2). It has been noticed that the core-shell nanocomposite achieved a maximum yield of 0.17 μmol/g-catalyst/h at the sixth hour of reaction in the visible light spectrum (i.e., 400 nm). They even concluded that the improved photoactivity of the composite catalyst was due to electron transmission between the TiO2 shell and MWCNTs that suppressed the electron
hole rearrangement, thus enhancing the overall efficiency of photocatalysis. To enhance the photocatalyst for CO2 reduction to methane, Kim et al. (2017) studied and synthesized a novel p-n-p hetero-junction (Cu2O/S-doped TiO2, shown in Fig. 3.5) catalyst. The catalyst displayed outstanding results in CO2 reduction to methane at AM 1.5 G illuminations, achieving 2.31 μmol/m2/h yield for CH4. It has been concluded

Figure 3.4 Reaction pathway for H2 and CO2 activation.


50

Carbon Dioxide Capture and Conversion

Figure 3.5 Step by step (Cu2O/S-TiO2/CuO) catalyst synthesis scheme.


Figure 3.6 (A) CH4 production rate by employing different photocatalysts for 1 h reaction time. (B) Schematic presentation of the reaction mechanism of CO2 hydrogenation to CH4 over Ag-doped N/TiO2 photocatalyst under the visible light spectrum.


that the yield is almost 10 times better than the ordinary TiO2 nanotube array films prepared under identical conditions. Khalid et al. (2017) synthesized metal (Cu and Ag) loaded nanosized N/TiO2 photocatalyst by a simple sol-gel technique and they tested the method successfully for CO2 hydrogenation reaction. The photocatalytic efficiency was estimated with visible light wavelength, λ 420 nm, and pressure of 1.25 atm. They found that Ag-doped N/TiO2 displayed superior performance than Cu
N/TiO2, N/TiO2, and TiO2 photocatalysts (Fig. 3.6A) for methane conversion from CO2. The improved catalyst activity was due to larger surface area, prolonged absorption of visible light, and hindrance of electron
hole pair association. The proposed reaction mechanism scheme is shown in Fig. 3.6B.

CO2 conversion technologies for clean fuels production

51

3.6 CO2 conversion into dimethyl ether CO2 conversion into dimethyl ether (DME) is an inclusive technique for CO2 utilization for the formation of a clean transportation fuel, which acts as an alternative to be used in compression ignition engines and it also serves as an excellent fuel for domestic use (Arbag et al., 2016). The thermal efficiency of combustion for DME is superior to other synthetic fuels, but similar to conventional fuels. The merits of DME as fuel are zero particulate carbon and sulfur oxide emissions, with diminished quantities of nitrous oxides in the exhaust. DME can be employed as a fuel in diesel engines, for running the turbines in power plants and as cooking fuel gas for domestic applications. Moreover, DME can act as source material for the generation of several chemicals, such as hydrocarbon fuels, olefins, and oxygenates (Bonura et al., 2014). The conventional method for DME synthesis is the dehydration of methanol catalyzed by an acidic catalyst. Direct conversion of CO2 to DME requires efficiently catalyzed methanol synthesis and methanol dehydration reactions by keeping the CO yield to the lowest, which is formed during the parallel RWGS reaction. Bonura et al. (2013) studied the amalgamated Cu
ZnO
ZrO2/HZSM5 system for single-step DME synthesis from CO2 (Fig. 3.7). It has been reported that the hybrid system Cu
ZnO
ZrO2/H-ZSM5 synthesized by physical mixing exhibited better performance. Based on the thermodynamic analysis, it has also been concluded that for improving the

Figure 3.7 The one-step and two-step processes for DME production. dimethyl ether.




,

52

Carbon Dioxide Capture and Conversion

DME productivity lower temperatures proved out to be better compared to higher temperatures (Eq. 3.8). This is because CO concentration rises drastically with temperature rise.
 CO2 6H2 CH3 OCH3 3H2 O ΔH298K 22:2 kJ=mol (3.8) Yang and Wang (2015) explained that direct conversion of syngas to DME is thermodynamically favored when compared to methanol formation. The direct DME synthesis from syngas consisting of H2, CO, and CO2 follows the two reactions i.e., with and without water
gas shift (WGS) reaction (Eqs. 3.9 and 3.10). 2CO

4H2

CH3 OCH3

H2 O

(3.9)

3CO

3H2

CH3 OCH3

CO2

(3.10)

Vakili and Eslamloueyan (2012) concluded that the direct synthesis of DME is more economical than the indirect synthesis (two-step) technique. They also reported that the heuristic reactor design with a counter-current flow pattern in the second reactor has a positive effect on the rate of DME production. To enhance the process economy, the Pinch analysis is carried out to find the optimized operating conditions. It has been observed that reactor type plays a key role in pinch analysis and thus DME production. The characteristics, benefits, and restraints of different reactor types have been recorded and listed in Table 3.3. It has been concluded that there is still a gap and scope for designing the reactor for DME production with optimized parameters and proper spatial scattering of catalyst in the reactor for better yield. Proper design of bifunctional catalysts and their strength associated with acidic spots is also a vital factor for better functioning of the process. However, other factors like the deactivation of catalysts by the blockage of catalytic pores and coverage of acidic sites are supposed to deactivate the zeolite-based catalyst. Other crucial considerations affecting DME formation were also studied by researchers, and it was evident that the reaction mixture containing water had a hindering effect on the rate of reaction rate since it competed with methanol molecules for acidic sites. For example, for water removal condition to prevail with hydrophilic membrane, the WGS reaction shifted the equilibrium to enhance the CO2 conversion to CH3OH, thus improving the selectivity and yield of the DME process (Kabir et al., 2013). However, regardless of various research on DME production so far, there is still a gap in research

CO2 conversion technologies for clean fuels production

53

Table 3.3 Comparison of different types of reactors for DME (dimethyl ether) production (Azizi et al., 2014). Reactor type

Characteristics and usage

Benefits in a DME plant

Considerations

Fixed beds

•




•

•

•

•

Slurry phase

Fluidized bed

•

•

Simplicity and lower cost Catalytic heterogeneous gas-phase reactions For catalytic reactions with low or intermediate heat of reaction The high conversion was achieved by decreasing the temperature along the reactor Catalytic heterogeneous gas-phase reactions Catalytic heterogeneous gas-phase reactions

• • •

•

• • • •

Coupled and dual type reactors

•

For both highly exothermic and endothermic reactions

• • •

Coupling reactor and separation units

• •

For methanol dehydration CD (or RD): distillation column and the reactor are combined

• • •

Manageable temperature better heat transfer Lower gas-solid mass transfer resistance Excellent temperature control High conversion and no need for recirculation Moderate operating pressure Lowering both capital and operating costs Highly energyefficient Hot spots can be controlled Higher selectivity/ conversion Reducing operational cost R-DWC: lowers footprint with the milder operating

• • •

•

•

Catalyst deactivation High recycling of syngas High operational investment High-pressure drops

Complicated equipment Loss of catalyst particles The collision between catalyst particles and the reactor wall Loss of catalyst

CD requires moderate temperature, while the employed catalyst is active at a higher temperature (Continued)

54

Carbon Dioxide Capture and Conversion

Table 3.3 (Continued) Reactor type

Characteristics and usage

•

•

Micro reactors

•

DWC: split the middle section of a single tower into two sections R-DWC: reactive dividing-wall column (based on DWC design) For both highly exothermic and endothermic reactions

Benefits in a DME plant

condition, better performance (energy saving, reduced CO2 emission, reduced total annual cost) •

• • •

Membrane reactors

•

Has been used in indirect and direct methods

Considerations

• • • • • • • • •

High controllability of the reaction conditions Small holdup value Avoiding thermal runaway Compactness and parallel processability Good reaction yield No additional steps of separation and purification Prevent the catalyst deactivation Dual bed membrane reactor: Higher thermal efficiency Reduces the cost of syngas production Spherical membrane reactor. Decreases the pressure drop Increases the DME production

•

Laminar flow behavior

•

May produce undesired HC Pore blockage Thermal/ mechanical stability issues

• •

Source: Reproduced with permission from Azizi, Z., Rezaeimanesh, M., Tohidian, T., and Rahimpour, M.R., 2014. Dimethyl ether: a review of technologies and production challenges. Chemical Engineering and Processing: Process Intensification, 82, 150
172.

CO2 conversion technologies for clean fuels production

55

covering the economic features related to the process. Furthermore, the studies related to scaling up and optimization of one-step technique for DME need to be studied.

3.7 CO2 conversion into gasoline As discussed earlier, the transformation of CO2 into hydrocarbons is being studied since the 1900s. Also, the synthesis of higher hydrocarbons (HHCs) (gasoline, diesel, olefins, alcohols) from oxides of carbon has been a topic of research for over a century now (Schulz, 1999). Inui et al. (1992) investigated the CO2 conversion to gasoline in a two-stage continuous flow tubular reactor (Fig. 3.8). They synthesized Cu-Zn-Cr-A1-oxides and H-Fe-silicate crystalline catalysts and placed them in the two reactors connected in series, respectively. The formation of methanol occurring in the first reactor was transformed to gasoline with 50% selectivity. Some light olefins were also formed as byproducts, which were recycled and converted into gasoline to enhance the efficiency of the overall process. Fischer-Tropsch synthesis is the most extensively used technique for gasoline and other HHC synthesis from oxides of carbon. However, there are several parameters that affect the selectivity range of hydrocarbon chain compound formed after synthesis. These factors are reaction temperatures, operating pressures, the catalyst used, and the type of reactor used to carry out the synthesis. Fe and Co are the most widely used catalysts for gasoline synthesis by the Fischer-Tropsch process at an industrial scale. In contrast, Ni and Ru are regular based catalysts for synthesizing HHCs (Schulz, 1999).

Figure 3.8 Schematic flow diagram of the two-stage reactor for CO2 conversion to gasoline.





56

Carbon Dioxide Capture and Conversion

Apart from Fischer-Tropsch synthesis, Eliasson et al. (2000) synthesized larger hydrocarbons directly from CH4 and CO2 by employing dielectric-barrier discharge (DBD) over zeolite catalysts. The products obtained by DBD included alkanes, alkenes, oxygenates, and syngas. They also concluded that product selectivity of HHCs depends on operating pressure, temperature, CO2/CH4 ratios, and power input. The results also displayed an increasing HHC trend on increasing the power input and proposed the mechanism of HHC formation from methyl radicals as follows: CH4

ðe; H; O; O

; OH; . . .Þ

CH3

ðH

e; H2 ; OH; OH

; H2 O; . . .Þ (3.11)

The following chain reactions may originate subsequently to form HHC: CH3 C 2 H6

CH3 e

C2 H5 C4 H10 C2 H5 C 2 H5

C 2 H6

C2 H5 C 2 H5

e

C4 H9

H

(3.12) e

C4 H10 H

(3.13) (3.14)

e

(3.15)

C 4 H9

C6 H14

(3.16)

CH3

C3 H8

(3.17)

Wei et al. (2017) conducted research on direct conversion of the CO2 to gasoline fuel ranges (i.e., C5-C11). A significant selectivity of 78% has been achieved over Na
Fe3O4/HZSM-5 zeolite catalyst, which is considerably stable (over 1000 h) and efficient with only 4% conversion into methane. The conversion of CO2 over different zeolite catalysts is shown in Fig. 3.9. The multifunctional zeolite catalyst possesses three kinds of active sites as Fe3O4, Fe5C2, and acid, which have displayed synergistic properties. The CO2 reduction over Fe3O4/HZSM-5 catalyst occurred in three steps. Firstly, reduction to CO through RWGS reaction, followed by Fischer-Tropsch synthesis giving consequent hydrogenated CO to α-olefin transition species. The final step includes the hydrocarbon formation (i.e., gasoline range, C5-C11) by acid-catalyzed oligomerization, isomerization, and aromatization reactions. The reaction proceeds over the zeolite catalyst, and hydrocarbons formed are selectively diffuse out of zeolite catalyst pores (Fig. 3.10).

CO2 conversion technologies for clean fuels production

57

Figure 3.9 CO2 conversion into different hydrocarbon ranges over various zeolite catalysts.

Figure 3.10 Schematic representation of CO2 hydrogenation reaction to form gasoline range hydrocarbon.

58

Carbon Dioxide Capture and Conversion

3.8 Conclusions The increased concentration of CO2 is a severe threat to the environment, which can successfully be transformed into a series of petrochemicals and fuels, including methane, methanol, and gasoline, including C5 to C11 hydrocarbons. The appropriate methods are achievable thermodynamically with variable reaction operating conditions. The methanation reaction is an encouraging technique to get rid of it and use it as valueadded fuel, i.e., CH4. Looking into the industrial point of view, heterogeneous catalysts, including Cu, Fe, and Ni-based, are economically more feasible. Catalysts related to the Cu particles covered with a range of oxides (i.e., ZnO, ZrO2, and TiO2) or metal catalysts with promoters were significantly studied as viable materials for processes involving conversion of CO2 to methanol. However, factors such as low methanol selectivity, low CO2 conversion rates, and sintering account for a change in concern to other potential catalysts, including carbides noble bimetallic systems. Investigations based on the transformation of CO2 to gasoline seem to be a promising way of utilizing atmospheric GHG and at the same time, producing a commercial fuel that is the demand in the present scenario. As per the available literature, only a limited amount of research work has been done for direct HHC synthesis (specifically gasoline range) from CO2. So far, zeolite-based systems have proved promising to be the key support materials because of the significant features related to structure/ acidity/basicity. There is a wide space in the development of the process regarding the gasoline selectivity, reaction mechanism study, optimum reactor design, and efficient catalyst.

Acknowledgments The authors would like to acknowledge the financial support provided by Universiti Teknologi PETRONAS, Malaysia under Yayasan Universiti Teknologi PETRONAS (YUTP), grant no. 015LC0-343.

References Alipour, Z., Rezaei, M., Meshkani, F., 2014. Effect of alkaline earth promoters (MgO, CaO, and BaO) on the activity and coke formation of Ni catalysts supported on nanocrystalline Al2O3 in dry reforming of methane. Journal of Industrial and Engineering Chemistry 20 (5), 2858
2863. Al
Swai, B.M., Osmana, N.B., Ramli, A., Abdullah, B., Farooqi, A.S., Ayodele, B.V., et al., 2021. Low-temperature catalytic conversion of greenhouse gases (CO2 and

CO2 conversion technologies for clean fuels production

59

CH4) to syngas over ceria-magnesia mixed oxide supported nickel catalysts. International Journal of Hydrogen Energy 46 (48), 24768
24780. Al-Swai, B.M., Osman, N., Alnarabiji, M.S., Adesina, A.A., Abdullah, B., 2019. Syngas production via methane dry reforming over ceria-magnesia mixed oxidesupported nickel catalysts. Industrial and Engineering Chemistry Research 58 (2), 539
552. Arbag, H., Yasyerli, S., Yasyerli, N., Dogu, G., Dogu, T., 2016. Enhancement of catalytic performance of Ni based mesoporous alumina by Co incorporation in conversion of biogas to synthesis gas. Applied Catalysis B: Environmental 198, 254
265. Arena, F., Barbera, K., Italiano, G., Bonura, G., Spadaro, L., Frusteri, F., 2007. Synthesis, characterization and activity pattern of Cu-ZnO/ZrO2 catalysts in the hydrogenation of carbon dioxide to methanol. Journal of Catalysis 249 (2), 185
194. Azizi, Z., Rezaeimanesh, M., Tohidian, T., Rahimpour, M.R., 2014. Dimethyl ether: a review of technologies and production challenges. Chemical Engineering and Processing: Process Intensification 82, 150
172. Baktash, E., Littlewood, P., Schomäcker, R., Thomas, A., Stair, P.C., 2015. Alumina coated nickel nanoparticles as a highly active catalyst for dry reforming of methane. Applied Catalysis B: Environmental 179, 122
127. Balasubramanian, P., Bajaj, I., Hasan, M.M.F., 2018. Simulation and optimization of reforming reactors for carbon dioxide utilization using both rigorous and reduced models. Journal of CO2 Utilization 23, 80
104. Barbarossa, V., Vanga, G., Viscardi, R., Gattia, D.M., 2014. CO2 as carbon source for fuel synthesis. Energy Procedia 45, 1325
1329. Beinik, I., Hellström, M., Jensen, T.N., Broqvist, P., Lauritsen, J.V., 2015. Enhanced wetting of Cu on ZnO by migration of subsurface oxygen vacancies. Nature Communications 6 (1), 8845. Bode, S., Jung, M., 2006. Carbon dioxide capture and storage
Liability for nonpermanence under the UNFCCC. International Environmental Agreements: Politics, Law and Economics 6 (2), 173
186. Bonura, G., Cordaro, M., Spadaro, L., Cannilla, C., Arena, F., Frusteri, F., 2013. Hybrid Cu
ZnO
ZrO2/H-ZSM5 system for the direct synthesis of DME by CO2 hydrogenation. Applied Catalysis B: Environmental 141, 16
24. Bonura, G., Cordaro, M., Cannilla, C., Mezzapica, A., Spadaro, L., Arena, F., et al., 2014. Catalytic behaviour of a bifunctional system for the one step synthesis of DME by CO2 hydrogenation. Catalysis Today 228, 51
57. Bowker, M., Hadden, R.A., Houghton, H., Hyland, J.N.K., Waugh, K.C., 1988. The mechanism of methanol synthesis on copper/zinc oxide/alumina catalysts. Journal of Catalysis 109 (2), 263
273. Brito, J.F.de, Zanoni, M.V.B., 2017. On the application of Ti/TiO2/CuO n-p junction semiconductor: a case study of electrolyte, temperature and potential influence on CO2 reduction. Chemical Engineering Journal 318, 264
271. Castro Luna, A.E., Iriarte, M.E., 2008. Carbon dioxide reforming of methane over a metal modified Ni-Al2O3 catalyst. Applied Catalysis A: General 343 (1
2), 10
15. Díez-Ramírez, J., Díaz, J.A., Sánchez, P., Dorado, F., 2017. Optimization of the Pd/Cu ratio in Pd-Cu-Zn/SiC catalysts for the CO2 hydrogenation to methanol at atmospheric pressure. Journal of CO2 Utilization 22, 71
80. Din, I.U., Shaharun, M.S., Subbarao, D., Naeem, A., Hussain, F., 2016. Influence of niobium on carbon nanofibres based Cu/ZrO2 catalysts for liquid phase hydrogenation of CO2 to methanol. Catalysis Today 259, 303
311. Din, I.U., Shaharun, M.S., Naeem, A., Tasleem, S., Johan, M.R., 2018. Carbon nanofibers based copper/zirconia catalysts for carbon dioxide hydrogenation to

60

Carbon Dioxide Capture and Conversion

methanol: effect of copper concentration. Chemical Engineering Journal 334, 619
629. ˇ Djinovi´c, P., Crnivec, I.G.O., Pintar, A., 2015. Biogas to syngas conversion without carbonaceous deposits via the dry reforming reaction using transition metal catalysts. Catalysis Today 253, 155
162. Eliasson, B., Liu, C.J., Kogelschatz, U., 2000. Direct conversion of methane and carbon dioxide to higher hydrocarbons using catalytic dielectric-barrier discharges with zeolites. Industrial and Engineering Chemistry Research 39 (5), 1221
1227. Etiope, G., Sherwood Lollar, B., 2013. Abiotic methane on earth. Reviews of Geophysics 51 (2), 276
299. Farooqi, A.S., Yusuf, M., Zabidi, N.A.M., Saidur, R., Shahid, M.U., Ayodele, B.V., et al., 2022. Hydrogen-rich syngas production from bi-reforming of greenhouse gases over zirconia modified Ni/MgO catalyst. International Journal of Energy Research 46 (3), 2529
2545. Ganesh, I., 2014. Conversion of carbon dioxide into methanol
A potential liquid fuel: fundamental challenges and opportunities (a review). Renewable and Sustainable Energy Reviews 31, 221
257. Geng, W., Han, H., Liu, F., Liu, X., Xiao, L., Wu, W., 2017. N,P,S-codoped C@nanoMo2C as an efficient catalyst for high selective synthesis of methanol from CO2 hydrogenation. Journal of CO2 Utilization 21, 64
71. Gui, M.M., Chai, S.P., Xu, B.Q., Mohamed, A.R., 2014. Enhanced visible light responsive MWCNT/TiO2 core-shell nanocomposites as the potential photocatalyst for reduction of CO2 into methane. Solar Energy Materials and Solar Cells 122, 183
189. Gupta, M., Coyle, I., Thambimuthu, K., 2003. CO2 Capture Technologies and Opportunities in Canada: “Strawman Document for CO2 Capture and Storage (CCandS) Technology Roadmap.” 1st Canadian CCandS Technology Roadmap Workshop, September, 18
19. Han, H., Geng, W., Xiao, L., Wu, W., 2019. High selective synthesis of methanol from CO2 over Mo2C@NSC. Journal of the Taiwan Institute of Chemical Engineers 95, 112
118. Huang, C., Chen, S., Fei, X., Liu, D., Zhang, Y., 2015. Catalytic hydrogenation of CO2 to methanol: study of synergistic effect on adsorption properties of CO2 and H2 in CuO/ZnO/ZrO2 system. Catalysts 5 (4), 1846
1861. IEA, 2006. CO2 Emissions from Fuel Combustion. OECD Publishing, Paris. Inui, T., Takeguchi, T., Kohama, A., Tanida, K., 1992. Effective conversion of carbon dioxide to gasoline. Energy Conversion and Management 33 (5
8), 513
520. Invernizzi, C.M., Iora, P., 2016. The exploitation of the physical exergy of liquid natural gas by closed power thermodynamic cycles. An overview. Energy 105, 2
15. Jadhav, S.G., Vaidya, P.D., Bhanage, B.M., Joshi, J.B., 2014. Catalytic carbon dioxide hydrogenation to methanol: a review of recent studies. Chemical Engineering Research and Design 92 (11), 2557
2567. Jang, J.G., Kim, G.M., Kim, H.J., Lee, H.K., 2016. Review on recent advances in CO2 utilization and sequestration technologies in cement-based materials. Construction and Building Materials 127, 762
773. Jang, W., Shim, J., Kim, H., Yoo, S., Roh, H., 2019. A review on dry reforming of methane in aspect of catalytic properties. Catalysis Today 324, 15
26. Kabir, K.B., Hein, K., Bhattacharya, S., 2013. Process modelling of dimethyl ether production from Victorian brown coal—integrating coal drying, gasification and synthesis processes. Computers and Chemical Engineering 48, 96
104. Khalid, N.R., Ahmed, E., Niaz, N.A., Nabi, G., Ahmad, M., Tahir, M.B., et al., 2017. Highly visible light responsive metal loaded N/TiO2 nanoparticles for photocatalytic conversion of CO2 into methane. Ceramics International, 49, 6771
6777.

CO2 conversion technologies for clean fuels production

61

Kim, H.R., Razzaq, A., Grimes, C.A., Il, S., 2017. Heterojunction p-n-p Cu2O/S-TiO2/ CuO: synthesis and application to photocatalytic conversion of CO2 to methane. Journal of CO2 Utilization 20, 91
96. Koizumi, N., Jiang, X., Kugai, J., Song, C., 2012. Effects of mesoporous silica supports and alkaline promoters on activity of Pd catalysts in CO2 hydrogenation for methanol synthesis. Catalysis Today 194 (1), 16
24. Lee, K.H., Lee, J.S., 1995. Effects of catalyst composition on methanol synthesis from CO2/H2. Korean Journal of Chemical Engineering 12 (4), 460
465. Li, H., Wang, J., 2004. Study on CO2 reforming of methane to syngas over Al2O3-ZrO2 supported Ni catalysts prepared via a direct sol-gel process. Chemical Engineering Science 59 (22
23), 4861
4867. Li, H., Xu, H., Wang, J., 2011. Methane reforming with CO2 to syngas over CeO2-promoted Ni/Al2O3-ZrO2 catalysts prepared via a direct sol-gel process. Journal of Natural Gas Chemistry 20 (1), 1
8. Liao, C.H., Horng, R.F., 2017. Experimental study of syngas production from methane dry reforming with heat recovery strategy. International Journal of Hydrogen Energy 42 (40), 25213
25224. Liaw, B.J., Chen, Y.Z., 2001. Liquid-phase synthesis of methanol from CO2/H2 over ultrafine CuB catalysts. Applied Catalysis A: General 206 (2), 245
256. Liu, Y., Zhang, Y., Wang, T., Tsubaki, N., 2007. Efficient conversion of carbon dioxide to methanol using copper catalyst by a new low-temperature hydrogenation process. Chemistry Letters 36 (9), 1182
1183. Marinoiu, A., Cobzaru, C., Raceanu, M., Varlam, M., Carcadea, E., Cernatescu, C., et al., 2015. Carbon dioxide conversion to methane over supported nickel base catalysts. Revue Roumaine de Chimie 60 (2
3), 249
256. Men, Y.-L., Liu, Y., Wang, Q., Luo, Z.-H., Shao, S., Li, Y.-B., et al., 2019. Highly dispersed Pt-based catalysts for selective CO2 hydrogenation to methanol at atmospheric pressure. Chemical Engineering Science 200, 167
175. Min, J.E., Lee, Y.J., Park, H.G., Zhang, C., Jun, K.W., 2015. Carbon dioxide reforming of methane on Ni-MgO-Al2O3 catalysts prepared by sol-gel method: effects of Mg/Al ratios. Journal of Industrial and Engineering Chemistry 26, 375
383. Muraza, O., Galadima, A., 2015. A review on coke management during dry reforming of methane. International Journal of Energy Research 39 (9), 1196
1216. Nagaraja, B.M., Bulushev, D.A., Beloshapkin, S., Ross, J.R.H., 2011. The effect of potassium on the activity and stability of Ni
MgO
ZrO2 catalysts for the dry reforming of methane to give synthesis gas. Catalysis Today 178 (1), 132
136. Nieva, M.A., Villaverde, M.M., Monzón, A., Garetto, T.F., Marchi, A.J., 2014. Steammethane reforming at low temperature on nickel-based catalysts. Chemical Engineering Journal 235, 158
166. Nitta, Y., Suwata, O., Ikeda, Y., Okamoto, Y., Imanaka, T., 1994. Copper-zirconia catalysts for methanol synthesis from carbon dioxide: effect of ZnO addition to Cu-ZrO2 catalysts. Catalysis Letters 26 (3
4), 345
354. Raudaskoski, R., Turpeinen, E., Lenkkeri, R., Pongrácz, E., Keiski, R.L., 2009. Catalytic activation of CO2: use of secondary CO2 for the production of synthesis gas and for methanol synthesis over copper-based zirconia-containing catalysts. Catalysis Today 144 (3
4), 318
323. Saito, M., Murata, K., 2004. Development of high performance Cu/ZnO-based catalysts for methanol synthesis and the water-gas shift reaction. Catalysis Surveys from Asia 8 (4), 285
294. Sastre, F., Puga, A.V., Liu, L., Corma, A., García, H., 2014. Complete photocatalytic reduction of CO2 to methane by H2 under solar light irradiation. Journal of the American Chemical Society 136 (19), 6798
6801.

62

Carbon Dioxide Capture and Conversion

Schulz, H., 1999. Short history and present trends of Fischer-Tropsch synthesis. Applied Catalysis A: General 186 (1
2), 3
12. Selvarajah, K., Phuc, N.H.H., Abdullah, B., Alenazey, F., Vo, D.V.N., 2016. Syngas production from methane dry reforming over Ni/Al2O3 catalyst. Research on Chemical Intermediates 42 (1), 269
288. Słoczy´nski, J., Grabowski, R., Kozłowska, A., Olszewski, P., Lachowska, M., Skrzypek, J., et al., 2003. Effect of Mg and Mn oxide additions on structural and adsorptive properties of Cu/ZnO/ZrO2 catalysts for the methanol synthesis from CO2. Applied Catalysis A: General 249 (1), 129
138. Sokolov, S., Kondratenko, E.V., Pohl, M., Barkschat, A., Rodemerck, U., 2012. Environmental stable low-temperature dry reforming of methane over mesoporous La2O3-ZrO2 supported Ni catalyst. Applied Catalysis B, Environmental 113
114, 19
30. Spencer, M.S., 1999. The role of zinc oxide in Cu/ZnO catalysts for methanol synthesis and the water
gas shift reaction. Topics in Catalysis 8 (3), 259. Tasfy, S.F.H., Zabidi, N.A.M., Shaharun, M.S., Subbarao, D., 2015. The role of support morphology on the performance of Cu/ZnO-catalyst for hydrogenation of CO2 to methanol. AIP Conference Proceedings (1669), 020001. Tursunov, O., Kustov, L., Tilyabaev, Z., 2017. Methanol synthesis from the catalytic hydrogenation of CO2 over CuO
ZnO supported on aluminum and silicon oxides. Journal of the Taiwan Institute of Chemical Engineers 78, 416
422. Vakili, R., Eslamloueyan, R., 2012. Optimal design of an industrial scale dual-type reactor for direct dimethyl ether (DME) production from syngas. Chemical Engineering and Processing: Process Intensification 62, 78
88. Wambach, J., Baiker, A., Wokaun, A., 1999. CO2 hydrogenation over metal/zirconia catalysts. Physical Chemistry Chemical Physics 1 (22), 5071
5080. Wang, W., Wang, S., Ma, X., Gong, J., 2011. Recent advances in catalytic hydrogenation of carbon dioxide. Chemical Society Reviews 40 (7), 3703
3727. Waugh, K.C., 1992. Methanol synthesis. Catalysis Today 15 (1), 51
75. Wei, J., Ge, Q., Yao, R., Wen, Z., Fang, C., Guo, L., et al., 2017. Directly converting CO2 into a gasoline fuel. Nature Communications 8 (1), 15174. Weigel, J., Koeppel, R.A., Baiker, A., Wokaun, A., 1996. Surface species in CO and CO 2 hydrogenation over copper/zirconia: on the methanol synthesis mechanism. Langmuir: The ACS Journal of Surfaces and Colloids 12 (22), 5319
5329. Xu, J., Zhou, W., Li, Z., Wang, J., Ma, J., 2009. Biogas reforming for hydrogen production over nickel and cobalt bimetallic catalysts. International Journal of Hydrogen Energy 34 (16), 6646
6654. Yang, N., Wang, R., 2015. Sustainable technologies for the reclamation of greenhouse gas CO2. Journal of Cleaner Production 103, 784
CO792. Yin, Y., Hu, B., Li, X., Zhou, X., Hong, X., Liu, G., 2018. Pd@zeolitic imidazolate framework-8 derived PdZn alloy catalysts for efficient hydrogenation of CO2 to methanol. Applied Catalysis B: Environmental 234, 143
152. Yusuf, M., Farooqi, A.S., Keong, L.K., Hellgardt, K., Abdullah, B., 2021. Contemporary trends in composite Ni-based catalysts for CO2 reforming of methane. Chemical Engineering Science 229, 116072. Zhang, M., Zhang, J., Zhou, Z., Chen, S., Zhang, T., Song, F., 2020. Effects of the surface adsorbed oxygen species tuned by rare-earth metal doping on dry reforming of methane over Ni/ZrO2 catalyst. Applied Catalysis B: Environmental 264, 118522. Zhang, R.J., Xia, G.F., Li, M.F., Wu, Y., Nie, H., Li, D.D., 2015a. Effect of support on the performance of Ni-based catalyst in methane dry reforming. Journal of Fuel Chemistry and Technology 43, 1359
1365.

CO2 conversion technologies for clean fuels production

63

Zhang, X., Zhang, Q., Tsubaki, N., Tan, Y., Han, Y., 2015b. Carbon dioxide reforming of methane over Ni nanoparticles incorporated into mesoporous amorphous ZrO2 matrix. Fuel 147, 243
252. Zhong, H., Yao, G., Cui, X., Yan, P., Wang, X., Jin, F., 2019. Selective conversion of carbon dioxide into methane with a 98% yield on an in situ formed Ni nanoparticle catalyst in water. Chemical Engineering Journal 357, 421
427.

CHAPTER 4

Upcycling of carbon from waste via bioconversion into biofuel and feed Siew Yoong Leong1, Shamsul Rahman Mohamed Kutty2, Pak Yan Moh3 and Qunliang Li4 1

Department of Petrochemical Engineering, Universiti Tunku Abdul Rahman, Kampar, Perak Darul Ridzuan, Malaysia Department of Civil and Environmental Engineering, Universiti Teknologi PETRONAS, Seri Iskandar, Perak Darul Ridzuan, Malaysia 3 Industrial Chemistry Programme, Faculty of Science and Natural Resources, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia 4 School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi, China 2

Abbreviations CAPEX CCS FAMEs GHG kgCO2eq OPEX PBR UN SDGs

capital expenditure carbon capture and storage fatty acid methyl esters greenhouse gas kilogram of carbon dioxide equivalents operating expense photobioreactor United Nations Sustainable Development Goals

4.1 Introduction Managing the emissions of carbon dioxide (CO2) has been always a daunting challenge facing all parties globally. Emission of CO2 is identified as the main culprit contributing to global warming besides fluorinated gases, nitrous oxide (N2O), and methane (CH4) (Deprá et al., 2020; Choi et al., 2019; Banerjee et al., 2020). The contribution of greenhouse gases (GHGs) especially CO2 is associated with numerous aspects whether directly or indirectly. The nonanthropogenic aspects are naturally occurring CO2 released from decomposition, ocean release, and respiration. In contrast, the anthropogenic aspects of CO2 emission are contributing from human activities such as combustions of fossil fuel, mainly from coal and petroleum sources, open burning, deforestation, land clearing for Carbon Dioxide Capture and Conversion DOI: https://doi.org/10.1016/B978-0-323-85585-3.00009-2

© 2022 Elsevier B.V. All rights reserved.

65

Upcycling of carbon from waste via bioconversion into biofuel and feed

67

compounds. Currently, the feedstock to produce bioethanol is primarily sugarcane, molasses, cassava, maize, wood and agricultural residues, leading to atmospheric environmental CO2 emissions. In the current situation, the removal of CO2 from the source of pollution through the bioconversion process is another solution to addressing the problem of GHGs. Examples of new revolutionary solutions are the upcycling of CO2 into new products and generating biofuels from CO2. This provides a new perspective on carbon capture and storage technologies that have been around for decades, proposing the technologies that turn global warming emissions into profits. For instance, establishing new technologies to mitigate and improve CO2 bioconversion strategy is through the microalgae-based carbon capture and utilization, anaerobic digestion, syngas fermentation, and enzymatic processes (Kondaveeti et al., 2020). The bioprocess of converting CO2 into microalgae biomass via photosynthesis is useful to produce bioenergy and other value-added products. The conversion of CO2 by microalgae is the current research interest. The natural ability of microalgae to biologically convert CO2 into chemicals and fuels has laid a sustainable platform for the biorefinery of gaseous carbon waste. The advantage of this biological process is the ability of this microorganism to metabolize carbon resource within the cells and the capability to generate valuable products (Deprá et al., 2020), which can be seen as complementary to traditional carbon capture and storage technology options (Choi et al., 2019). Bioconversion of CO2 with microalgae has gained popularity from biorefineries owing to its potential to uptake and utilize a huge amount of CO2 (El-Dalatony et al., 2016). Microalgae are unicellular photosynthetic microorganisms. It assimilates CO2 as a source of carbon and nutrients to obtain its algal biomass with the assistance of a light source (sunlight) during the photosynthetic process. One successful way to capture CO2 is via the industrial waste stream, where the CO2 captured can be directly distributed to the microalgae medium during the bioconversion process. Additionally, carbon capture using microalgal is seen as a viable implementation for the conversion of anthropogenic CO2. In addition, microalgae cultivation is considered sustainable, as it is not competing with crops, can help to reduce pollution by capturing CO2, has higher growth rates than plants, does not require large space of land, and can be cultivated in brackish or marine water (Banerjee et al., 2020). Biomasses of microalgae contain a wide range of nutrients such as lipids, protein, carbohydrates, and pigments (Nethravathy et al., 2019;

68

Carbon Dioxide Capture and Conversion

Khan et al., 2018a,b; Brindhadevi et al., 2021). As shown in Fig. 4.1, nutrient derives from this biological conversion has been described as a sustainable process in which valuable products such as biodiesel, bioethanol, and fatty acids are simultaneously produced (Kondaveeti et al., 2020). Microalgae can be cultivated under three main conditions: autotrophic, mixotrophic, and heterotrophic. Microalgae are usually cultivated under photoautotrophic conditions. Photoautotrophic microalgae are species capable of performing photosynthetic processes using sunlight, CO2 as their energy, and organic substrate as a carbon source (Hu et al., 2018). Open systems for the cultivation of microalgae are widely practiced for a commercial establishment. This system is mostly used for photoautotrophic microalgae cultivation as it provides many advantages such as the ability to harness the natural photon energy sources from sunlight and absorb CO2 from the atmosphere, minimum set-up, and low operating expenses and less energy intensive (Brennan and Owende, 2010; Hu et al., 2018). Other photoautotrophic microalgae cultivation using closed photobioreactors is referred to as closed system cultivation. Generally, this system is more effective as it generates higher biomass productivity, uses minimum space, and has a

Figure 4.1 Bioconversion of microalgae for biofuel and feed.

Upcycling of carbon from waste via bioconversion into biofuel and feed

69

high surface area to volume ratio, thus increasing light illumination and significantly reducing contamination (Narala et al., 2016). Microalgal biomass is considered as the third generation feedstock for biofuel production. Naturally, microalgae can accumulate huge amounts of lipids and carbohydrates, which in turn can be converted into biodiesel and bioethanol, respectively (Table 4.1). The triacylglycerol contains in the microalgae’s lipids is between 20% and 80% by dry weight, which makes it suitable to be used for biodiesel synthesis. Biodiesel is monoalkyl esters of long-chain fatty acids (fatty acid methyl esters, FAMEs), which can be obtained by lipid transesterification accompanied by homogeneous or heterogeneous catalysts and more than alcohol (Abdelaziz, et al., 2013). Several strains of microalgae have been identified for their lipid-rich accumulations (Table 4.2). Attention has been focused on Dunaliella tertiolecta (Tang et al., 2011), Nannocloropsis sp., and Botryococcus braunii to produce biofuel through CO2 upcycling (Kumar et al., 2018). Bioethanol is derived from the fermentation of microalgae biomass, which is a convincing alternative resource for liquid biofuel (da Maia et al., 2020). Fermentation requires less energy input and performs under easy and mild operating conditions compared to the biodiesel production system. In addition, the CO2 produced because of the fermentation process can be redirected to the cultivation of microalgae as a carbon source (Fig. 4.2). This circular process will help to reduce GHG emissions (Gendy and El-Temtamy, 2013). Bioethanol from microalgae showed higher productivity compared with conventional plant crops such as sugarcane and corn. Approximately 50% of their dry weight consists of carbohydrates, which are mainly in the form of starch and cellulose (de Farias Silva and Bertucco, 2016). Hence, the carbohydrate content is easily hydrolyzed to fermentable sugars (El-Dalatony et al., 2016; Phwan et al., 2018). Before fermentation processes, a pretreatment or saccharification step is needed to break down carbohydrates or starch into simple sugars (Phwan et al., 2018). The pretreatment step is essential for fermentative microorganisms to be easily accessible to starch and to resolve biomass recalcitrance for bioethanol production (Gallego et al., 2015; El-Dalatony et al., 2016). Fermentation of bioethanol can be achieved through separate hydrolysis and fermentation, simultaneous saccharification and fermentation, and simultaneous saccharification and co-fermentation (Mohd Azhar et al., 2017). Besides biofuel, microalgae are an alternative protein source with several advantages over other currently used protein sources such as fishmeal and plant-based proteins (Caporgno and Mathys, 2018). Studies have shown that microalgae protein could be used as a future food source such as animal feed

Table 4.1 Summary of various algae strains uses culture using CO2 as the carbon source for biotechnical application. Microorganism

Growth medium

Biotechnical application

Yield

Reference

Chlamydomonas sp. KNM0029C

Modified Tris-AcetatePhosphate medium at 4C

0.22 g bioethanol/g residual biomass; 0.16 g FAME/g

Kim et al. (2020)

Chlorella sorokiniana BTA 9031 Chlorella sp.

Blue Green-11 medium

Bioethanol and biodiesel Biodiesel

0.95 g/L

Blue Green-11 medium

protein-based

1.2 g/L

Chlorella vulgaris C. vulgaris P12

Blue Green-11 medium Original growth medium

Biodiesel Bioethanol

1.38 g/L of lipid


Chlorococcum humicola

Artificial seawater

Bioethanol




Dunaliella tertiolecta

Artificial seawater

Biofuel

1.8 g/L

Dunaliella tertiolecta (UTEX LB 999) Phormidium valderianum BDU 20041

Erdschreiber’s medium

Biodiesel

0.4 g/L

Artificial sea nutrient

Biodiesel

61.3 mg/L/d

Mondal et al. (2017) Salati et al. (2017) Li et al. (2019) Dragone et al. (2011) Harun and Danquah (2011) Kumar et al. (2018) Tang et al. (2011) Dineshbabu et al. (2020)

Table 4.2 Fatty acid component derived from various algae strains. Algae

Culture condition

Fatty acid components (%) Saturated fatty acid

Reference

Unsaturated fatty acid

Microalgae Dunaliella tertiolecta Dunaliella tertiolecta Dunaliella tertiolecta Scenedesmus sp. Pseudokirchneriella subcapitata (H1)a Chlorella emersonii (H1)a Chlorella vulgaris C. vulgaris UTEX

Florescence light White LEDs Red LEDs Autotrophic Bold basal medium

26.9 27.2 26.4 21.2 22.6

73.1 72.8 73.6 78.8 25.9

Bold basal medium Salinity (0.5%) Treated urban wastewater and Bayfolan

0.6 36.1 54.9

4.4 62.0 45.1

Tang et al. (2011)

Pandey et al. (2020) Priyanka et al. (2020)

Trivedi et al. (2019) Fernández-Linares et al. (2017)

Macroalgae Jania rubens Ulva linza Padina pavonica a

Harvested naturally from Abu Qir Bay coast

40.5

37.3

71.4 58.4

18.3 14.4

Other fatty acid of Pseudokirchneriella subcapitata and Chlorella emersonii neutral lipids by purified lipase from Pseudomonas reinekei (H1).

El Maghraby, Fakhry (2015)

72

Carbon Dioxide Capture and Conversion

Figure 4.2 Microalgae bioconversion of CO2 to bioethanol production.

(Dineshbabu et al., 2019; Torres-Tiji et al., 2020). In addition, bioactive compounds are one of the key characteristics of microalgae with possible human health benefits. For instance, cyanobacteria (Spirulina) and chlorophytes (Chlorella) are the most widely studied species for biotechnological development purposes. Species of Chlorella are often marketed as health supplement products owing to their benefits as functional foods to prevent diseases like Alzheimer’s disease and/or cancer (Caporgno and Mathys, 2018). Spirulina is one of the most well-studied algae since it is particularly abundant in carotenoids, essential fatty acids, proteins, complex carbohydrates, vitamins, minerals, and pigments. Spirulina contains approximately 46%
71% of protein, 8%
16% of carbohydrates, and 4%
9% of lipids (of its dry weight) (Radhakrishnan et al., 2017). Table 4.3 summarizes the nutritional profile of Chlorella sp. and Spirulina sp.

4.3 Upcycling of carbon by insect larvae In addition to the microalgae upcycling of gaseous CO2 emissions from anthropogenic activities, in-situ carbon sequestration provides an alternate route to eliminate large-scale CO2 emissions from the organic waste source itself before release to the atmosphere. One alternative approach is to introduce insect larvae at the point source for the recovery of organic waste. This pathway would help to capture and prevent carbon losses from being released

Upcycling of carbon from waste via bioconversion into biofuel and feed

Table 4.3 Nutritional profile of

and

. a

Chlorella

Property

73

b

Spirulina

Proximate composition (Radhakrishnan et al., 2017) Protein (%) Carbohydrate (%) Lipid (%) Ash (%) Moisture (%) Gross energy k.cal/g

55.7 15.3 10.7 9 6.3 2.7 a,b

61.7 10.9 5.1 9 5.6 2.8

Fatty acid composition (%)

Myristic acid Heptadecanoic acid Stearic acid Oleic acid Palmitoleic acid Omega-3 acid Omega-6 acid Linoleic acid (LA) acid γ-linoleic acid (GLA) acid Palmitic acid

2.4 2 4.1 20.2 4.2 47 17.2

0.2 0.4 0.7 1.4 6 9 9.5 15 16 23

Essential amino acid (%) (Thorp and Bowes, 2016) Isoleucine Leucine Phenylalanine Valine Pigments

26.7 31.1 26.4 28.1

31.3 34.4 35.2 35.6

Vitamin content (per 100 g of dry cells) (Andrade et al., 2018) Vitamin A (mg) Vitamin C (mg) Vitamin B1 (mg) Vitamin B2 (mg) Vitamin B3 (mg) Vitamin B5 (mg) Vitamin B6 (mg) Vitamin B9 (μg) Vitamin B12 (μg) Vitamin E (α-tocopherol) (mg) Vitamin K (phylloquinone) (μg)

30.8 10.4 1.7 4.3 23.8 1.1 1.4 94 0.1 1.5 -

0.34 10.1 2.4 3.7 12.8 0.4 94 5.0 25.5 (Continued)

74

Carbon Dioxide Capture and Conversion

Table 4.3 (Continued) a

Chlorella

Property

b

Spirulina

Mineral content (mg/100 g) (Radhakrishnan et al., 2017) Ca Na K P Cu Zn Fe Mg Mn a

0.004 0.35 0.37 17.2 0.015 0.062 0.226 5.24 0.063

0.003 0.512 0.322 15.2 0.003 0.041 0.135 0.811 0.048

Chlorella fatty acid (Hultberg et al., 2014). Spirulina fatty acid (Liestianty et al., 2019).

b

to the atmosphere as CO2. In other words, this path paved the way for the harvesting and upcycling of carbon nutrients from the point source. The existence of abundance organic carbon in biomass is of great importance because of the ability of the larvae to retain carbon and to apply nutrients through the assimilation of the organic carbon source within their biomass. Insects’ larvae are currently being viewed as part of the solution to a global issue such as carbon mitigation. As a result of perishable waste, such as food loss, they function as the “carbon converter” has gained global attention as an agent for CO2 mitigation. Embedding insects into organic waste for the conversion of carbon sources and minimizing the loss of gaseous carbon to landfills can help to offset or minimize CO2 emissions during the decomposition process, contributing to the emission of GHGs. Insects are often associated with the disease, a vector, a pest, and a nuisance. Due to the negative societal perception, little or no attention has been focused on the insect as a potential candidate for ecological treatment or as biological control. On another aspect, the insect does play a prominent role as part of the mitigation of many global challenges. These include the solution to sustainable food, energy and water system, deforestation, environmental pollution, and health inequities (Prather and Laws, 2018). Moreover, insects in waste management have a key role to play in future carbon management, offering the potential to reduce GHG emissions and generate sustainable economic revenues. Food loss and waste have contributed to major loss and underutilization of resources, increasing GHG emissions, and global warming and climate change (FAO, 2020). Approximately 1.3 billion tonnes of food is lost or

84

Carbon Dioxide Capture and Conversion

Table 4.5 The opportunity and challenges in bioconversion.

Opportunities

Microalgae

Insect larvae

• Biofuel derived from algae have low to zero CO2 emissions

• Provide a platform for community recycling and improve local industrial competitiveness • Established sustainable livelihood projects for waste scavengers, such as creating new jobs in the insect farming industry. Hence, it ensures that the lower middle-class society has a source of income and thereby decreases poverty • Encouragement and support of local governments to allocate budget and land space, assess relevant technologies, and consider strategic partners for service provision, such as the private sector or nongovernmental organizations (The World Bank, 2018) • Promoting circular bioeconomy via waste upcycling for renewable fuel, protein-rich feed, and biofertilizer (Skrivervik, 2020)

• Algae are capable of assimilating CO2 as they grow. Taking the benefit of its nature algae is a “biofactory” for carbon capture and sequestration

• Offers great opportunities for investment in projects that enhance photobioreactors technologies for product development, such as feed, pharmaceutical, nutraceutical, and biomaterial through technology transfer • Algae do not compete with natural resources as the cultivation utilizes saline water or wastewater

(Continued)

Upcycling of carbon from waste via bioconversion into biofuel and feed

85

Table 4.5 (Continued)

Challenges

Microalgae

Insect larvae

• High capital and energy costs, especially on a low scale

• Ensuring food safety for human consumption should be considered such as microbial, chemical, physical, allergenic, parasitical, and toxicological risks (Govorushko, 2019) • Establishing the legislation on the best practices in quality and hygienic insect production (Bryne, 2019) • Establishing legal classification of organic resources and safety (Gasco et al., 2020)

• Incurring unnecessary costs for the purification of algae due to contamination of bacteria • Challenging to obtain an algal strain with a high accumulation of lipid and carbohydrate content and fast growth rate, easy to harvest, cost-effective, and high adaptability with different environments (Marwa et al., 2019) • The major technical challenges for algae are low biomass productivity, high harvesting cost, low efficiency, land and water-intensive for algae cultivated in ponds or bioreactors (Dineshkumar and Sen, 2020; Yadav and Sen, 2018) • Microalgae have yet to show to be economically and ecologically viable to produce biodiesel, biomethane, bioethanol, and biohydrogen in quantities large enough to replace fossil fuels (Brindhadevi et al., 2021)

• High variance in the incoming waste source can affect the proliferation of insect larvae. The inconsistency of waste quality would also affect the nutritional value of larvae to be used for animal feed • Improper waste management practices such as insufficient segregation of organic waste, inadequate collection, transport, and storage facilities

86

Carbon Dioxide Capture and Conversion

4.7 Conclusions CO2 is the most abundant waste produced by human activities. However, the concentration of CO2 released in the atmosphere must be managed to safeguard the ecosystem from being further polluted. With the unprecedented outbreak of the COVID-19 pandemic, innovation and technological development seem vital to seeking sustainable solutions to both economic and environmental problems, such as increased resources and energy conservation. Generating something valuable from waste will also help to offset the costs of waste management and land issues. In addition, turning waste into a profitable commodity would help to achieve economic growth and sustainable development. One specific example is to increase the usage of renewable energy and changing the way products are produced and used leads to the reduction of the ecological footprint and climate change mitigation. One of these is the integration of bioconversion technologies and is closely related to the numerous sustainable development goals (UN SDGs), including industry, innovation and infrastructure, sustainable consumption and patterns of production, and immediate action to tackle climate change and its impacts. In addition, the extension of scientific research and innovation, development infrastructure, and the transition of research and development capabilities to developing countries cannot be achieved by a single organization alone. However, a great deal of effort is required from various sectors or stakeholders to invest in modern, sustainable infrastructure in developing countries or to upgrade existing infrastructure to make it more sustainable. To date, there is still a lack of an integrated biorefinery system for bio-based commodities for circular bioeconomy advancement. In the future, biorefinery based on renewable biomass is expected to be recognized as a biological carbon sequestration tool and an unconventional resource for pharmaceutical, nutraceutical, biomaterial, and biofuel development. Not to be overlooked, the reduction, conversion, and use of GHG-derived carbon sources for useful chemicals and fuels are not limited to bioconversion technologies.

References Abdelaziz, A.E.M., Leite, G.B., Hallenbeck, P.C., 2013. Addressing the challenges for sustainable production of algal biofuels: II. Harvesting and conversion to biofuels. Environmental Technology 34 (13), 1807
1836.

Upcycling of carbon from waste via bioconversion into biofuel and feed

87

Ahmed, R., Liu, G., Yousaf, B., Abbas, Q., Ullah, H., Ali, M.U., 2020. Recent advances in carbon-based renewable adsorbent for selective carbon dioxide capture and separation
a review. Journal of Cleaner Production 242, 1
20. Andrade, L.M., Andrade, C.J., Dias, M., Nascimento, C.A.O., Mendes, M.A., 2018. Chlorella and spirulina microalgae as sources of functional foods, nutraceuticals, and food supplements; an overview. MOJ Food Process Technology 6 (1), 45
58. Angelidaki, I., Treu, L., Tsapekos, P., Luo, G., Campanaro, S., Wenzel, H., et al., 2018. Biogas upgrading and utilization: current status and perspectives. Biotechnology Advances 36 (2), 452
466. Banerjee, S., Banerjee, S., Ghosh, A.K., Das, D., 2020. Maneuvering the genetic and metabolic pathway for improving biofuel production in algae: present status and future prospective. Renewable and Sustainable Energy Reviews 133, 1
18. Belghit, I., Liland, N.S., Waagbo, R., Biancarosa, I., Pelusio, N., Li, Y.X., et al., 2018. Potential of insect-based diets for Atlantic salmon (Salmo salar). Aquaculture (Amsterdam, Netherlands) 491, 72
81. Bott, M., Eikmanns, B., Thauer, R.K., 1986. Coupling of carbon-monoxide oxidation to CO2 and H2 with the phosphorylation of Adp in acetate-grown Methanosarcina barkeri. European Journal of Biochemistry 159 (2), 393
398. Braungart, M., McDonough, W. (Eds.), 2009. Cradle to Cradle: Remaking the Way We make Things. Vintage, London, UK. Brennan, L., Owende, P., 2010. Biofuels from microalgae—a review of technologies for production, processing, and extractions of biofuels and co-products. Renewable and Sustainable Energy Reviews 14 (2), 557
577. Brindhadevi, K., Mathimani, T., Rene, E.R., Shanmugam, S., Chi, N.T.L., Pugazhendhi, A., 2021. Impact of cultivation conditions on the biomass and lipid in microalgae with an emphasis on biodiesel. Fuel 284, 1
8. Bryne, J., 2019. Guidance for EU insects food and feed sector in how to implement best hygiene practices. From William Reed Business Media Ltd. Available from https:// www.feednavigator.com/Article/2019/02/25/New-guidance-for-EU-insect-foodand-feed-sector (accessed 20.10.20). Caporgno, M.P., Mathys, A., 2018. Trends in microalgae incorporation into innovative food products with potential health benefits. Frontiers in Nutrition 5 (58), 1
10. Choi, Y.Y., Patel, A.K., Hong, M.E., Chang, W.S., Sim, S.J., 2019. Microalgae Bioenergy with Carbon Capture and Storage (BECCS): an emerging sustainable bioprocess for reduced CO2 emission and biofuel production. Bioresource Technology Reports 7, 1
14. da Maia, J.L., Cardoso, J.S., da Silveira Mastrantonio, D.J., Bierhals, C.K., Moreira, J.B., Costa, J.A.V., et al., 2020. Microalgae starch: a promising raw material for the bioethanol production. International Journal of Biological Macromolecules 165 (Part B), 2739
2749. Daniels, L., Fuchs, G., Thauer, R., Zeikus, J., 1977. Carbon monoxide oxidation by methanogenic bacteria. Journal of Bacteriology 132 (1), 118
126. de Farias Silva, C.E., Bertucco, A., 2016. Bioethanol from microalgae and cyanobacteria: a review and technological outlook. Process Biochemistry 51 (11), 1833
1842. Demirbas, M.F., Balat, M., 2009. Progress and recent trends in biogas processing. International Journal of Green Energy 6 (2), 117
142. Deprá, M.C., Dias, R.R., Severo, I.A., de Menezes, C.R., Zepka, L.Q., Jacob-Lopes, E., 2020. Carbon dioxide capture and use in photobioreactors: the role of the carbon dioxide loads in the carbon footprint. Bioresource Technology 314, 1
10. Devic, E., Leschen, W., Murray, F., Little, D.C., 2018. Growth performance, feed utilization and body composition of advanced nursing Nile tilapia (Oreochromis niloticus) fed

88

Carbon Dioxide Capture and Conversion

diets containing Black Soldier Fly (Hermetia illucens) larvae meal. Aquaculture Nutrition 24 (1), 416
423. Diender, M., Pereira, R., Wessels, H.J., Stams, A.J., 2016. Proteomic analysis of the hydrogen and carbon monoxide metabolism of Methanothermobacter marburgensis. Frontiers in Microbiology 7 (1049), 1
10. Dineshkumar, R., Sen, R., 2020. A sustainable perspective of microalgal biorefinery for co-production and recovery of high-value carotenoid and biofuel with CO2 valorization. Biofuels, Bioproducts and Biorefining 14 (4), 879
897. Dineshbabu, D., Goswami, G., Kumar, R., Sinha, A., Das, D., 2019. Microalgae
nutritious, sustainable aqua- and animal feed source. Journal of Functional Foods 62, 1
14. Dineshbabu, G., Uma, V.S., Mathimani, T., Prabaharan, D., Uma, L., 2020. Elevated CO2 impact on growth and lipid of marine cyanobacterium Phormidium valderianum BDU 20041
towards microalgal carbon sequestration. Biocatalysis and Agricultural Biotechnology 25, 1
7. Dragone, G., Fernandes, B.D., Abreu, A.P., Vicente, A.A., Teixeira, J.A., 2011. Nutrient limitation as a strategy for increasing starch accumulation in microalgae. Applied Energy 88 (10), 3331
3335. EIA, 26 September, 2019. Energy and the environment explained: Greenhouse gases and the climate. Retrieved from U.S. Energy Information Administration. Available from: https://www.eia.gov/energyexplained/energy-and-the-environment/greenhousegases-and-the-climate.php (accessed 28.10.20). El Maghraby, D.M., Fakhry, E.M., 2015. Lipid content and fatty acid composition of Mediterranean macro-algae as dynamic factors for biodiesel production. Oceanologia 57 (1), 86
92. El-Dalatony, M.M., Kurade, M.B., Abou-Shanab, R.A.I., Kim, H., Salama, E.S., Jeon, B. H., 2016. Long-term production of bioethanol in repeated-batch fermentation of microalgal biomass using immobilized Saccharomyces cerevisiae. Bioresource Technology 219, 98
105. Elia, A.C., Capucchio, M.T., Caldaroni, B., Magara, G., Dörr, A.J.M., Biasato, I., et al., 2018. Influence of Hermetia illucens meal dietary inclusion on the histological traits, gut mucin composition and the oxidative stress biomarkers in rainbow trout (Oncorhynchus mykiss). Aquaculture (Amsterdam, Netherlands) 496, 50
57. European Commission, 2017. Commission regulation (EU) 2017/893 of 24 May 2017 amending Annexes I and IV to regulation (EC) No 999/2001 of the European Parliament and of the Council and Annexes X, XIV and XV to Commission Regulation (EU) No 142/2011 as regards the provisions on processed animal protein. Official Journal of the European Union 60, 92
116. FAO, 2020. Technical Platform on the Measurement and Reduction of Food Loss and Waste. From Food and Agriculture Organization of the United Nations. Available from: http://www.fao.org/platform-food-loss-waste/en/ (accessed 19.10.20). Fatimah, Y.A., Govindan, K., Murniningsih, R., Setiawan, A., 2020. Industry 4.0 based sustainable circular economy approach for smart waste management system to achieve sustainable development goals: a case study of Indonesia. Journal of Cleaner Production 269, 1
15. Fernández-Linares, L.C., Barajas, C.G., Páramo, E.D., Corona, J.A.B., 2017. Assessment of Chlorella vulgaris and indigenous microalgae biomass with treated wastewater as growth culture medium. Bioresource Technology 244 (1), 400
406. Folayan, A.J., Anawe, P.A., Aladejare, A.E., Ayeni, A.O., 2019. Experimental investigation of the effect of fatty acids configuration, chain length, branching and degree of unsaturation on biodiesel fuel properties obtained from lauric oils, high-oleic and high-linoleic vegetable oil biomass. Energy Reports 5, 793
806.

Upcycling of carbon from waste via bioconversion into biofuel and feed

89

Gallego, L.J., Escobar, A., Peñuela, M., Peña, D., Rios, L.A., 2015. King grass: a promising material for the production of second-generation butanol. Fuel 143, 399
403. Gasco, L., Biancarosa, I., Liland, N.S., 2020. From waste to feed: a review of recent knowledge on insects as producers of protein and fat for animal feeds. Current Opinion in Green and Sustainable Chemistry 23, 67
79. Gendy, T.S., El-Temtamy, S.A., 2013. Commercialization potential aspects of microalgae for biofuel production: an overview. Egyptian Journal of Petroleum 22 (1), 43
51. Giannetti, B.F., Agostinho, F., Eras, J.J.C., Yang, Z., Almeida, C.M.V.B., 2020. Cleaner production for achieving the sustainable development goals. Journal of Cleaner Production 271, 1
9. Giannetto, A., Oliva, S., Lanes, C., de Araújo Pedron, F., Savastano, D., Baviera, C., et al., 2020. Hermetia illucens (Diptera: Stratiomydae) larvae and prepupae: biomass production, fatty acid profile and expression of key genes involved in lipid metabolism. Journal of Biotechnology 307, 44
54. Govorushko, S., 2019. Global status of insects as food and feed source: a review. Trends in Food Science and Technology 91, 436
445. Hannah, R., Max, R., 2020. Environmental impacts of food production. OurWorldInData.org. Available from: https://ourworldindata.org/environmentalimpacts-of-food (accessed 5.11.20). Harun, R., Danquah, M.K., 2011. Influence of acid pre-treatment on microalgal biomass for bioethanol production. Process Biochemistry 46 (1), 304
309. Hu, J., Nagarajan, D., Zhang, Q., Chang, J.S., Lee, D.J., 2018. Heterotrophic cultivation of microalgae for pigment production: a review. Biotechnology Advances 36 (1), 54
67. Hultberg, M., Jönsson, H.L., Bergstrand, K.J., Carlsson, A.S., 2014. Impact of light quality on biomass production and fatty acid content in the microalga Chlorella vulgaris. Bioresource Technology 159, 465
467. Huyben, D., Vidakovi´c, A., Hallgren, S.W., Langeland, M., 2018. High-throughput sequencing of gut microbiota in rainbow trout (Oncorhynchus mykiss) fed larval and pre-pupae stages of black soldier fly (Hermetia illucens). Aquaculture (Amsterdam, Netherlands) 500, 485
491. Ishak, S., Kamari, A., 2019. Biodiesel from black soldier fly larvae grown on restaurant kitchen waste. Environmental Chemistry Letters 17, 1143
1150. Khan, M.I., Shin, J.H., Kim, J.D., 2018a. The promising future of microalgae: current status, challenges, and optimization of a sustainable and renewable industry for biofuels, feed, and other products. Microbial Cell Factories 17 (36), 1
21. Khan, S.A., Malla, F.A., Rashmi, Malav, L.C., Gupta, N., Kumar, A., 2018b. Potential of wastewater treating Chlorella minutissima for methane enrichment and CO2 sequestration of biogas and producing lipids. Energy 150, 153
163. Kim, E.J., Kim, S., Choi, H., Ha, S.J., 2020. Co-production of biodiesel and bioethanol using psychrophilic microalga Chlamydomonas sp. KNM0029C isolated from Arctic sea ice. Biotechnology for Biofuels 13 (20), 1
13. Kondaveeti, S., Abu-Reesh, I.M., Mohanakrishna, G., Bulut, M., Pant, D., 2020. Advanced Routes of Biological and Bio-electrocatalytic Carbon Dioxide (CO2) Mitigation Toward Carbon Neutrality. Frontiers in Energy Research 8 (94), 1
24. Kumar, A., Guria, C., Pathak, A.K., 2018. Optimal cultivation towards enhanced algaebiomass and lipid production using Dunaliella tertiolecta for biofuel application and potential CO2 bio-fixation: effect of nitrogen deficient fertilizer, light intensity, salinity and carbon supply strategy. Energy 148, 1069
1086. Kutty, S.R.M., Leong, S.Y., Tan, C.K., 2015. Growth performance, waste reduction and efficiency of conversion of digested food waste by Hermetia illucens larvae via bioconversion. Journal of Pure and Applied Microbiology 9, 533
537.

90

Carbon Dioxide Capture and Conversion

Lasaridi, K., Stentiford, E., 2011. Upcycling organic waste in a world of thinly distributed resources. Waste Management and Research 29 (11), 1115
1116. Leong, S.Y., 2016. Biodiesel production using Hermetia illucens (Black Soldier Fly) prepupae biomass through organic waste upcycling. PhD thesis, Universiti Teknologi PETRONAS, Tronoh, Perak, Malaysia. Leong, S.Y., Kutty, S.R.M., 2020. Characteristic of Hermetia illucens fatty acid and that of the fatty acid methyl ester synthesize based on upcycling of perishable waste. Waste and Biomass Valorization 11, 5607
5614. Leong, S.Y., Kutty, S.R.M., Malakahmad, A., Tan, C.K., 2016. Feasibility study of biodiesel production using lipids of Hermetia illucens larva fed with organic waste. Waste Management 47, 84
90. Li, Q., Zheng, L., Qiu, N., Cai, H., Tomberlin, J.K., Yu, Z., 2011. Bioconversion of dairy manure by black soldier fly (Diptera: Stratiomyidae) for biodiesel and sugar production. Waste Management 31 (6), 1316
1320. Li, M., Zhou, M., Lou, J., Tan, C., Tian, X., Su, P., et al., 2019. Carbon dioxide sequestration accompanied by bioenergy generation using a bubbling-type photosynthetic algae microbial fuel cell. Bioresource Technology 280, 95
103. Liestianty, D., Rodianawati, I., Arfah, R.A., Assa, A., Patimah, Sundari Muliadi, 2019. Nutritional analysis of spirulina sp. To promote as superfood candidate. IOP Conference Series: Materials Science and Engineering 509, 1
7. Linser, S., Lier, M., 2020. The contribution of sustainable development goals and forestrelated indicators to national bioeconomy progress monitoring. Sustainability 12 (7), 1
25. Marwa, G.S., Noura, S.D., Mohamed, S.Z., Hesham, M.S., 2019. Algal biofuels: current status and key challenges. Energies 12 (10), 1
22. Mohd Azhar, S.H., Abdulla, R., Jambo, S.A., Marbawi, H., Gansau, J.A., Mohd Faik, A. A., et al., 2017. Yeasts in sustainable bioethanol production: a review. Biochemistry and Biophysics Reports 10, 52
61. Mondal, M., Ghosh, A., Tiwari, O.N., Gayen, K., Das, P., Mandal, M.K., et al., 2017. Influence of carbon sources and light intensity on biomass and lipid production of Chlorella sorokiniana BTA 9031 isolated from coalfield under various nutritional modes. Energy Conversion and Management 145, 247
254. Narala, R.R., Garg, K., Sharma, K.K., Thomas-Hall, S.R., Deme, M., Li, Y., et al., 2016. Comparison of microalgae cultivation in photobioreactor, open raceway pond, and a two-stage hybrid system. Frontiers in Energy Research 4 (29), 1
10. Nethravathy, M.U., Jitendra, G.M., Sandeep, N.M., Ajam, Y.S., 2019. Recent advances in microalgal bioactives for food, feed, and healthcare products: commercial potential, market space, and sustainability. Comprehensive Reviews in Food Science and Food Safety 19 (6), 1882
1897. Newton, G., Booram, C., Barker, R., Hale, O., 1977. Dried larvae meal as a supplement for swine. Journal of Animal Science 44 (3), 395
400. Otero, P., Gutierrez-Docio, A., del Hierro, J.N., Reglero, G., Martin, D., 2020. Extracts from the edible insects Acheta domesticus and Tenebrio molitor with improved fatty acid profile due to ultrasound assisted or pressurized liquid extraction. Food Chemistry 314, 1
9. Pandey, A., Gupta, A., Sunny, A., Kumar, S., Srivastava, S., 2020. Multi-objective optimization of media components for improved algae biomass, fatty acid and starch biosynthesis from Scenedesmus sp. ASK22 using desirability function approach. Renewable Energy 150, 476
486. Paul, A., Frederich, M., Megido, R.C., Alabi, T., Malik, P., Uyttenbroeck, R., et al., 2017. Insect fatty acids: a comparison of lipids from three Orthopterans and Tenebrio molitor L. larvae. Journal of Asia-Pacific Entomology 20 (2), 337
340.

Upcycling of carbon from waste via bioconversion into biofuel and feed

91

Phwan, C.K., Ong, H.C., Chen, W.H., Ling, T.C., Ng, E.P., Show, P.L., 2018. Overview: comparison of pretreatment technologies and fermentation processes of bioethanol from microalgae. Energy Conversion and Management 173, 81
94. Prather, C.M., Laws, A.N., 2018. Insects as a piece of the puzzle to mitigate global problems: an opportunity for ecologists. Basic and Applied Ecology 26, 71
81. Priyanka, P., Kinsella, G.K., Henehan, G.T., Ryan, B.J., 2020. Enzymatic in-situ transesterification of neutral lipids from simulated wastewater cultured Chlorella emersonii and Pseudokirchneriella subcapitata to sustainably produce fatty acid methyl esters. Bioresource Technology Reports 11, 1
9. Radhakrishnan, S., Bhavan, P.S., Seenivasan, C., Muralisankar, T., 2017. Nutritional profile of Spirulina platensis, Chlorella vulgaris and Azolla pinnata to novel protein source for aquaculture feed formulation. Austin Journal of Aquaculture and Marine Biology 2 (1), 1
8. Rother, M., Metcalf, W.W., 2004. Anaerobic growth of Methanosarcina acetivorans C2A on carbon monoxide: an unusual way of life for a methanogenic archaeon. Proceedings of the National Academy of Sciences of the United States of America 101 (48), 16929
16934. Salati, S., D’Imporzano, G., Menin, B., Veronesi, D., Scaglia, B., Abbruscato, P., et al., 2017. Mixotrophic cultivation of Chlorella for local protein production using agrofood by-products. Bioresource Technology 230, 82
89. Shumo, M., Osuga, I.M., Khamis, F.M., Tanga, C.M., Fiaboe, K.K.M., Subramanian, S., et al., 2019. The nutritive value of black soldier fly larvae reared on common organic waste streams in Kenya. Scientific Reports 9, 1
13. Skrivervik, E., 2020. Insects’ contribution to the bioeconomy and the reduction of food waste. Heliyon 6 (5), 1
9. Su, C.H., Nguyen, H.C., Bui, T.L., Huang, D.L., 2019. Enzyme-assisted extraction of insect fat for biodiesel production. Journal of Cleaner Production 223, 436
444. Surendra, K.C., Tomberlin, J.K., van Huis, A., Cammack, J.A., Heckmann, L.H.L., Khanal, S.K., 2020. Rethinking organic wastes bioconversion: evaluating the potential of the black soldier fly (Hermetia illucens (L.)) (Diptera: Stratiomyidae) (BSF). Waste Management 117, 58
80. Tang, H., Abunasser, N., Garcia, M.E.D., Chen, M., Simon, Ng, K.Y., Salley, S.O., 2011. Potential of microalgae oil from Dunaliella tertiolecta as a feedstock for biodiesel. Applied Energy 88 (10), 3324
3330. The World Bank, 2018. What a Waste: An Updated Look into the Future of Solid Waste Management. The World Bank Group. Available from: https://www.worldbank.org/ en/news/immersive-story/2018/09/20/what-a-waste-an-updated-look-into-thefuture-of-solid-waste-management (acessed 15.10.20). Thorp, J.M., Bowes, R.E., 2016. Carbon sources in riverine food webs: new evidence from amino acid isotope techniques. Ecosystems 20, 1029
1041. Torres-Tiji, Y., Fields, F.J., Mayfield, S.P., 2020. Microalgae as a future food source. Biotechnology Advances 41, 1
13. Trivedi, T., Jain, D., Mulla, N.S.S., Mamatha, S.S., Damare, S.R., Sreepada, R.A., et al., 2019. Improvement in biomass, lipid production and biodiesel properties of a euryhaline Chlorella vulgaris NIOCCV on mixotrophic cultivation in wastewater from a fish processing plant. Renewable Energy 139, 326
335. van der Ha, D., Nachtergaele, L., Kerckhof, F.M., Rameiyanti, D., Bossier, P., Verstraete, W., et al., 2012. Conversion of biogas to bioproducts by algae and methane oxidizing bacteria. Environmental Science and Technology 46 (24), 13425
13431. Wang, J., 2014. Decentralized biogas technology of anaerobic digestion and farm ecosystem: opportunities and challenges. Frontiers in Energy Research 2 (10), 1
12.

92

Carbon Dioxide Capture and Conversion

Weththasinghe, P., Hansen, J.Ø., Nøkland, D., Lagos, L., Rawski, M., Øverland, M., 2021. Full-fat black soldier fly larvae (Hermetia illucens) meal and paste in extruded diets for Atlantic salmon (Salmo salar): effect on physical pellet quality, nutrient digestibility, nutrient utilization and growth performances. Aquaculture (Amsterdam, Netherlands) 530, 1
12. Yadav, G., Sen, R., 2018. Sustainability of microalgal biorefinery: scope, challenges, and opportunities. In: De, S., Bandyopadhyay, S., Assadi, M., Mukherjee, D. (Eds.), Sustainable Energy Technology and Policies. Green Energy and Technology. Springer, Singapore. Yang, S., Liu, Z., 2014. Pilot-scale biodegradation of swine manure via Chrysomya megacephala (Fabricius) for biodiesel production. Applied Energy 113, 385
391. Zabranska, J., Pokorna, D., 2018. Bioconversion of carbon dioxide to methane using hydrogen and hydrogenotrophic methanogens. Biotechnology Advances 36 (3), 707
720. Zheng, L., Hou, Y., Li, W., Yang, S., Li, Q., Yu, Z., 2012. Exploring the potential of grease from yellow mealworm beetle (Tenebrio molitor) as a novel biodiesel feedstock. Applied Energy 101, 618
621. Zieli´nska, E., Baraniak, B., Kara´s, M., Jakubczyk, A., 2015. Selected species of edible insects as a source of nutrient composition. Food Research International 77, 460
466.

CHAPTER 5

Organic base-mediated fixation of CO2 into value-added chemicals Cong Chien Truong1 and Dinesh Kumar Mishra2 1

Department of Bio-functional Molecular Engineering, University of Toyama, Toyama, Japan Department of Chemical Engineering/Research Institute of Industrial Science, Hanyang University, Seoul, Republic of Korea

2

Abbreviations 9-BBN BEMP BH3 BH3NH3 BINAP catBH CH2Cl2 CH3CN CH3OH CyTBG CyTEG CyTMG DABCO DBN DBU DEA DFT DIPEA DMAc DMAP DMF DMPA DMSO DPPA DPPCl Et3N EtBr FTIR-ATR

9-borabicyclo[3.3.1]nonane 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2diazaphosphorine borane ammonia borane 2,20 -bis(diphenylphosphino)-1,10 -binaphthyl catecholborane dichloromethane acetonitrile methanol N-cyclohexyl-N0 ,N0 ,N,vNv-tetrabutylguanidine N-cyclohexyl-N0 ,N0 ,N,vNv-tetraethylguanidine N-cyclohexyl-N0 ,N0 ,N,vNv-tetramethylguanidine 1,4-diazabicyclo [2.2.2]octane 1,5-diazabicyclo[4.3.0]non-ene 1,8-diazabicyclo(5.4.0)-7-undecene diethanolamine density functional theory N,N-diisopropylethylamine N,N-dimethylacetamide 4-dimethylaminopyridine dimethylformamide N,N-dimethylpropanolamine dimethyl sulfoxide diphenylphosphoryl azide diphenyl chlorophosphite triethylamine ethyl bromide Fourier transform infrared spectroscopy-attenuated total reflection

Carbon Dioxide Capture and Conversion DOI: https://doi.org/10.1016/B978-0-323-85585-3.00010-9

© 2022 Elsevier B.V. All rights reserved.

93

94

Carbon Dioxide Capture and Conversion

LiOtBu MCR Me2AlCl MgBr2 Mn Mim MTBD MTHP NaBH4 NBS n-BuLi Ni(acac)2 (bpy) NMP PEG PhTMG S8 TBD t-BuTEG t-Bu-TMG Td THF TMG TMP TOF TON TsCl

lithium tert-butoxide multicomponent reaction dimethylaluminum chloride magnesium bromide molecular number 1-methylimidazole 7-metyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene 4-methyltetrahydropyran sodium borohydride N-bromosuccinimide n-butyllithium nickel(II) acetylacetonate 2,20 -bipyridine N-methyl-2-pyrrolidone polyethylene glycol tetramethylphenylguanidine sulfur 1,5,7-triazabicyclo[4.4.0]dec-5-ene 2-tert-butyl-1,1,3,3-tetraethylguanidine 2-tert-butyl-1,1,3,3-tetramethylguanidine decomposition temperature tetrahydrofuran N,N,N0 ,N0 -tetramethylguanidine 2,2,6,6-tetramethylpiperidine turnover frequency turnover number tosyl chloride

5.1 Introduction Since the onset of the industrial revolution, the consumption of fossil fuels, coal, oil, and natural gases for transportation, energy production, industry, and anthropogenic activities has escalated to a great extent. As a result, the surging emission of greenhouse gases, e.g., carbon dioxide (CO2), resulted in serious impacts on the global environment and human societies. Indeed, the concentration of CO2 in the atmosphere has accumulated up to 384 ppm since the pre-industrial time, and the annual emission of CO2 (1970
2004) was reported to rise from 21 to 38 gigatons (Yu et al., 2008). Incessant endeavors in both science and technology to control and mitigate the accumulation of CO2 have been undertaken over the past few years. For example, several international protocols and conferences on “climate change” gave consent to legislations to reduce the CO2 source from human activities. In another direction, carbon capture and storage (CCS) along with carbon capture and utilization (CCU) has been proposed to offer potential solutions

Organic base-mediated fixation of CO2 into value-added chemicals

95

for the management of CO2 (Otto et al., 2015; Mac Dowell et al., 2017). In the CCS strategy, CO2 will be selectively removed from the gas streams and deposited in underground or undersea storage sites, yet major challenges such as safety, scalability, expenditure, and energy consumption need to be thoroughly addressed. Inversely, the CCU paradigm allows for the conversion of waste CO2 into valuable chemicals and fuels through the chemical, photo/electrochemical, photoelectrochemical, or biological patterns. Thanks to the abundant, benign, and cheap properties, CO2 has been flexibly deployed as a novel building block and renewable phosgene-isocyanate alternative for the green manufacture of value-added products (Sakakura et al., 2007; Liu et al., 2015). Towards this end, various synthetic strategies have been developed to overcome the intrinsic inertness and thermodynamic stability of CO2, thereby driving the chemical fixation of CO2 to happen effectively and selectively (Song et al., 2017). Organic bases are an important class of organocatalysts in synthetic chemistry because of their multifaceted functions (Ishikawa, 2009). Generally, these species are readily soluble in most organic solvents, making them suitable to facilitate the reaction mixture homogeneously. Typically, numerous derivatives of amidine and guanidine served as nucleophilic bases in a wide range of transformations (Taylor et al., 2012). In the domain of CO2 capture, aminebased solutions and task-specific ionic liquids (ILs) derived from organic superbases proved to be effective for CO2 absorption in the aspect of reversibility and capacity (Heldebrant et al., 2010). Owing to these reasons, common organic amines (Et3N, DEA, DABCO, DMAP, etc.) or superbases (DBU, TMG, DBN, etc.) have drawn great attention and appear to be potential candidates for the catalytic fixation of CO2 into valuable products. In this chapter, an elaborate overview on the manufacture of urea, carbamates, carbonates, polymers, carboxylic acids, methanol, N-formamides, N-methylamines, and five/six-membered heterocycles starting from CO2 feedstock under the catalysis of homogeneous organic bases is drawn. Furthermore, a deep insight into the function of these basic catalysts on the conversion of CO2 is delineated through mechanistic descriptions.

5.2 Organic base-mediated transformation of CO2 into value-added products 5.2.1 Linear/cyclic urea and carbamoyl azides In previous studies on the reversible chemisorption of CO2, several typical examples of the organic base-derived absorbents with superior absorptive

96

Carbon Dioxide Capture and Conversion

performance as compared to other ionic liquid systems were reported (Heldebrant et al., 2010; Wang et al., 2010). Likewise, Yang et al. (2011) established a novel absorbent composed of DBU-polyethylene glycol 150 (DBU-PEG150), which enabled an equimolar capture of CO2 at room temperature to provide the corresponding liquid amidinium alkylcarbonate salt. Subsequently, this resulting salt as the activated form of CO2 (3 mmol) was treated with aliphatic mono- and diamines (0.25 mmol) at 110°C within 24 h in the absence of any solvents to deliver 1,3-disubstituted urea (1,3-DSUs) in good to excellent yields. Xu et al. (2019) stated that a broad library of diaryl/dialkyl/alkyl-aryl urea products could be readily furnished upon heating silylamines and CO2 (5 atm) at 120°C in pyridine. According to the mechanistic proposal, silylcarbamates derived from the interaction of silylamines and CO2 were initially generated as reactive intermediates, which later underwent thermal conversion with silylamines to afford target substituted urea. Meanwhile, Marchegiani et al. (2017) reported the direct synthesis of 1,3-DSUs from the solvent-free coupling of primary aliphatic amines with CO2 over organic superbases. Herein, the catalytic activity of these cyclic bases was observed to depend on pKa and in the following order: TMG (pKa 23.3) t-Bu-TMG (23.5B24.5) DBU (24.3) BEMP (27.58) MTBD (25.49) TBD (26), ascribable to both basicity and structural effects (i.e., steric hindrance and hydrogen bonding). Thanks to these cooperative factors, 10 mol% of TBD could deliver 12%
65% yields of 1,3-DSUs when unhindered aliphatic amines were treated with CO2 (15 MPa) at 100°C in the absence of any organic solvents and dehydrating agents. Unfortunately, TBD was unable to convert hindered/unsaturated amines into urea products under identical conditions. Similarly, these authors also achieved a collection of imidazolidin-2-ones in the yield range of 47%
87% upon implementing the TBD-mediated coupling of propargyl amines and primary amines with CO2 at 100°C under solventfree conditions. Alternatively, Paz et al. (2010) explored the binary catalyst system of PhTMG
DPPA to obtain good to excellent yields of imidazolidin-2ones when the coupling of 1,2-diamines and CO2 was performed in CH3CN or CH2Cl2. In this situation, the presence of DPPA as a dehydrative activator was indispensable since it helped to facilitate the carboxylative cyclization of carbamate intermediate. Manaka et al. (2020) established a mild and indirect approach to produce urea from the CO2-derived ammonium salts, where ammonium

Organic base-mediated fixation of CO2 into value-added chemicals

97

carbamate was converted into a 35% yield of urea over a DBU catalyst at 100°C. To bypass undesirable pitfalls during the production of carbamoyl azides such as the consumption of toxic/explosive reagents or low yields of target products, a convenient synthetic pathway starting from CO2 was reported by Garcia-Egido et al. (2008). In this context, the mixture of amines (i.e., primary/secondary amines and pure α-amino esters), diphenylphosphoryl azide, and atmospheric CO2 was treated with PhTMG in CH3CN below 0°C, finally delivering 69%
90% isolated yields of carbamoyl azides.

5.2.2 Linear/cyclic carbamates Carbamates represent an important class of bioactive compounds, which are extensively employed in the production of preservatives, agrochemicals, pharmaceuticals, or useful synthons and protecting groups in synthetic chemistry (Ghosh and Brindisi, 2015). In contrast to the classical approaches involving the handle of chloroformates, isocyanates, or toxic reagents (Ozaki, 1972; Chaturvedi, 2011), most of the current research on the ecofriendly manufacture of linear/cyclic carbamates has shifted toward the utilization of CO2 as a starting material (Chaturvedi et al., 2012). McGhee et al. (1994, 1995) described a high-yielding synthesis of aliphatic carbamates from the two-step coupling of CO2 and primary/ secondary/aromatic amines with alkyl halides, where a stoichiometric loading of sterically hindered guanidine bases (i.e., CyTMG, CyTEG, t-BuTEG, and CyTBG) was examined as an effective catalyst. In this circumstance, steric hindrance, as well as great charge delocalization of these substituted guanidines, was conducive to the excellent yield and selectivity of urethane products. Later, Pérez et al. (2002) described the synthesis of N-alkyl ethyl carbamates from amines, ethyl iodide, and well-defined DBU
CO2 adduct in anhydrous CH3CN. For that purpose, amines initially undertook the transcarboxylation with reactive DBU
CO2 zwitterion to provide the carbamate
DBU intermediates, which were subsequently converted into 77%
96% yields of corresponding N-ethyl carbamates by the O-alkylation with ethyl iodide. In contrast, Zhao et al. (2014) stated that the combination of DBU
CH3CN was able to trigger the direct formation of methyl Nphenyl carbamate (MPC) from CO2, aniline, and methanol. Under optimal conditions with 5.6 wt.% of DBU as the main catalyst, the conversion of aniline and selectivity of MPC were achieved at 7.1% and 25.3%,

98

Carbon Dioxide Capture and Conversion

respectively. However, this protocol offered poor results of alkyl N-phenyl carbamates (APCs) upon expanding the scope of linear alcohols (C2
C4) because the conversion of aniline and selectivity of corresponding APCs significantly decreased in line with increasing steric hindrance of alkyl chains. By employing the MCR strategy, Franz et al. (2018) were successful in constructing a collection of heterocyclic carbamates upon coupling acyl chlorides, amines, and CO2 with substituted derivatives of 2,5-dihydro-thiazole/oxazole over Et3N at room temperature. In this two-step sequence, activated iminium anions obtained from the interaction of acyl chlorides and thiazoles/oxazoles would be trapped by in-situ generated carbamic acids (CO2 amines) to deliver corresponding N-acyl thia- and oxazolidinyl carbamates with a broad scope of yield and functional group compatibility (yield: 29%
91%). Significantly, this introduced pattern was also operable for the multigram synthesis of monocarbamates as well as biscarbamate monomers containing allyl units. Recently, the catalytic fixation of CO2 into functionalized cyclic carbamates, i.e., oxazolidinones, has been considerably investigated due to the wide applications of these privileged molecules in both synthetic and medicinal chemistry (Pulla et al., 2013). Generally, the divergent manufacture of oxazolidinones from CO2 could be fulfilled under the catalysis of organic bases/superbases, in which CO2 was coupled with various reagents such as 1,2-amino alcohols (Muñoz et al., 2009), N-propargylamines (Costa et al., 1998; Zhao et al., 2017), and N-substituted-2-chloroacetoamides (Galliani et al., 2009). Strikingly, these organic bases/ superbases (0.1
2 equivalents) enabled the access of different oxazolidinones (yield: 18%
99%) at a low pressure of CO2 (0.1
0.5 MPa). Besides, Zhou et al. (2019) stated that 5 mol% of TBD was effective to facilitate the carboxylate cyclization of N-propargylamides with CO2 under ambient conditions (25°C, 1 atm of CO2 and 1 h), finally rendering (Z) 5-alkylidene 1,3-oxazolidine-2,4-diones in good yields and excellent chemo-/stereoselectivity. Through the DFT calculations, the crucial role of TBD was established by the dual activation of both starting reagents during the insertion of CO2 into the N
H bond of N-propargylamides (rate-determining step).

5.2.3 Linear/cyclic carbonates Over the past decades, the chemical fixation of CO2 into organic carbonates has become one of the most attractive CCU paradigms owing to

Organic base-mediated fixation of CO2 into value-added chemicals

99

the broad applications of carbonates in the industry (Shaikh and Sivaram, 1996). In this context, many protocols leading to the production of linearcyclic carbonates from CO2 have been introduced (Sakakura and Kohno, 2009). To avoid the usage of organic solvents, metal catalysts along with the high pressure of CO2 during the manufacture of linear carbonates, Shang et al. (2019) introduced the solvent-free coupling of alcohols and alkyl bromides with CO2 under the catalysis of recyclable TMG. At a mild temperature of 50°C, a set of linear asymmetrical carbonates in the yield range of 36.8%
95% could be directly mildly afforded from atmospheric CO2. Apart from linear products, cyclic carbonates are also considered as one of the top value-added chemicals in the conversion of CO2 owing to their versatile use as green solvents, electrolytes, and precursors for polycarbonates/polyurethanes (Webster, 2003; Parker et al., 2014). The most common and simple pattern leading to cyclic carbonates from CO2 is associated with the cycloaddition of epoxides, where a variety of well-defined catalysts have been introduced (Buttner et al., 2017). Typically, metal-and halide-free bifunctional organocatalysts would be more favorable because the manufacturing process would not be contaminated by toxic materials. For example, Roshan et al. (2014) reported the practicality of alkanolamines in the solvent-free synthesis of propylene carbonate (PC), where DMPA was able to convert propylene oxide (PO) into 91% yield of PC. In this case, the synergistic effect of amine and hydroxyl groups was attributed to the activity of this catalyst. Kim et al. (2017) designed a multifunctional alkanolamine, i.e., bis(methylpiperazinyl)triol, by a facile one-step procedure and applied it for the cycloaddition of CO2 and PO. Thanks to the presence of many functional groups (four units of amine and three units of hydroxyl) in the structure, this catalyst triggered 90%
98% yields of PC under a mild condition (100°C
120°C, 5 bar of CO2). In another example, tertiary diamines such as N,N,N0 ,N0 tetramethylethylenediamine (TMEDA), N,N,N0 ,N0 -tetraethylethylenediamine (TEEDA), and N,N,N0 ,N0 -tetrahexylethylenediamine (THEDA) were reported as a green and simple class of organocatalysts in the solvent-free cycloaddition of CO2 to various POs (Cho et al., 2016). Among them, TEEDA with an appropriate molecular structure was found to be the most active catalyst, thereby allowing for a broad collection of five-membered cyclic carbonates in high selectivity ( 99%) with a low loading amount (0.1 mol%). As shown in Fig. 5.1, the catalysis of tertiary (TEEDA) and multifunctional alkanolamine (bis (methylpiperazinyl)triol) in the production of PC from epoxides and CO2 is illustrated.

100

Carbon Dioxide Capture and Conversion

Figure 5.1 Synthesis of cyclic carbonates from CO2 and propylene oxides over the , , 0 , 0 -tetraethylethylenediamine and bis(methylpiperazinyl)triol catalyst.

In recent years, the direct production of cyclic carbonates from CO2 and olefins has drawn much interest due to the higher availability and lower cost/ toxicity of starting alkenes as compared to epoxides (Sun et al., 2010; Wang et al., 2020). Generally, this sequential strategy involving epoxidation and carboxylative cyclization could be accomplished in either a single-step or onepot, two-step approach. In this situation, the requirement of oxidizing agents, expensive metal/ionic liquid catalysts, low yields, and numerous oxidationderived byproducts were major limitations. In contrast, Eghbali and Li (2007) disclosed that the combination of NBS
DBU could induce the direct conversion of terminal olefins and

Organic base-mediated fixation of CO2 into value-added chemicals

101

CO2 into five-membered cyclic carbonates in the absence of both metals and oxidants. Unfortunately, this aqueous-phase protocol required a stoichiometric amount of NBS and twofold loading of DBU to achieve moderate to quantitative yields of carbonate products. In this setting, a high loading of DBU was essential because it helped to deprotonate the weekly acidic O
H bond of alcohol and to neutralize the released HBr during the reaction. Wu et al. (2014) upgraded this DBU-mediated paradigm by designing a gas
liquid flow system for the convenient fixation of CO2 with olefins. This rational continuous flow design allowed the two-step sequence of hydroxybromination and carboxylation to take place with considerable efficiency with respect to conventional bath reactors since it was capable of: 1. enhancing the reaction rate by minimizing the incompatibility of NBS and DBU; 2. adjusting the reaction variables (residence time and temperature) to optimize the single step; 3. hampering the generation of epoxides and dibromide byproducts; 4. avoiding phase transfer reagents; 5. broadening the scope of olefins (aliphatic/aromatic/heteroaromatic); 6. suppressing the undesired formation of epoxides and 1,2-dibromoalkanes. As a result, an improvement in reaction parameters such as low loading of DBU (1.3 equivalents), low pressure of CO2 (180 psi), mild temperature (40°C
100°C), and the short period (40 min) was observed. Hence, 43%
89% yields of aliphatic/aromatic cyclic carbonates were readily achieved with this multistep flow system. Apart from epoxides and olefins, alkylene halohydrins were also deployed as benign and convenient reagents for the manufacture of CO2-derived cyclic carbonates. Although high yields of carbonates could be obtained under mild conditions over alkali metal carbonates (Truong and Mishra, 2020), the generation of waste metal bicarbonates and metal halides remained troublesome. Prompted by the practicality of organic bases in CO2 conversion, Zhou et al. (2009) were successful in preparing PC from the Et3N-mediated coupling of o-chloropropanol and CO2 under the solvent-free condition at 100°C. Similarly, Ochoa-Gómez et al. (2011) reported the dual function of Et3N as both a catalyst and a solvent for a 90% yield of glycerol carbonate from the direct coupling of 3-chloro-1,2-propanediol and CO2. Khokarale and Mikkola (2019) revealed that DBU could facilitate the one-pot production of ethylene carbonate (EC) and PC from CO2 and

102

Carbon Dioxide Capture and Conversion

alkylene halohydrines (1,2- and 1,3-alkylene chloro-, bromo-, and iodohidrins) over 90% yields under a solvent-free condition. In comparison with alkali metal carbonate catalysts, DBU showed superiority and convenience in this strategy because it enabled a faster transformation and a facile recyclability. Through the in-situ nuclear magnetic resonance (NMR) analysis, the establishment of EC or PC was verified through the carboxylation cyclization of ionic liquid derived from DBU
alkylene halohidrine
CO2. Another phosgene-free preparation of cyclic carbonates was achieved by the catalytic fixation of CO2 and diols, which directly delivered six-, seven-, and eight-membered ring cyclic carbonates. For instance, Gregory et al. (2015) introduced a ternary catalyst system of DBU
TsCl
Et3N for the one-pot, two-step coupling of CO2 and 1,3-diols for sixmembered cyclic carbonates under a mild condition (room temperature and 1 atm of CO2). Through the DFT calculations and experimental analyses, the cyclization was proposed to follow a sequence of addition
elimination, finally rendering cyclic carbonates with no inversion of stereochemistry in a maximal yield of 70%. McGuire et al. (2018) employed the binary mixture of TMP/ Et3N
TsCl for the simple one-step generation of six-, seven-, and eightmembered cyclic carbonates from CO2. Lately, a critical study on the CO2 addition to 1,x-diols for cyclic/acyclic carbonates over two different catalyst systems of DBU
EtBr and Et3N
TsCl was presented by Brege et al. (2020). Indeed, the DFT calculations and in-situ FTIR-ATR analysis corroborated that the product composition could be tunable by the appropriate system. In this circumstance, the mixture of DBU (2 equivalents)
EtBr (2.4 equivalents) allowed for the favorable formation of cyclic carbonates and/or bicarbonates depending on the starting diols. On the other hand, the binary composite of Et3N (2 equivalents)
TsCl (1 equivalent) selectively generated cyclic carbonates as main products under identical conditions. It is noteworthy that α-alkylidene cyclic carbonates could be established from the carboxylative coupling of CO2 with propargyl alcohols (Li et al., 2020), where a variety of catalysts, including metals, ionic liquids, N-hetetrocyclic carbenes, and organocatalysts, were widely deployed. Alternatively, Ca et al. (2011) indicated that various α-alkylidene cyclic carbonates were achievable from propargylic alcohols and supercritical/gaseous CO2 in the metal- and additive-free fashion by using TBD or MTBD as the main catalyst. Similarly, a library of oxoalkyl

Organic base-mediated fixation of CO2 into value-added chemicals

103

carbonates, oxoalkyl carbamates, or α-alkylidene oxazolidinones was produced in high yields from the TBD/MTBD-mediated cascade reaction of propargyl alcohols, CO2, and external nucleophiles (i.e., alcohols, phenols, or primary/secondary amines). In Fig. 5.2, the mechanistic pathways leading to CO2-based products over TBD or MTBD are clearly described.

5.2.4 Polyureas
polycarbonates Polyurea (PU), an important class of elastomers in the polymer industry, is extensively distributed in various applications of coatings, adhesives, spray molding, food packaging, and spandex production (Howarth, 2003). In addition, PUs can be deployed as raw materials during the manufacture of carbamates (Shang et al., 2012; Li et al., 2016). Thanks to the intrinsic urea linkage and intermolecular hydrogen bonding, the outstanding properties of PUs such as great versatility and physical
chemical durability (e.g., strong resistance toward organic solvents, moisture, abrasion, corrosion, low permeability, and high thermal stability) are well recognized (Qiao et al., 2011; Wang et al., 2019). Conventionally, the simplest production of PUs results from the coupling of diamines and toxic

Figure 5.2 Tentative formation of different products through the fixation of CO2 with propargyl alcohols and external nucleophiles in the presence of TBD or MTBD.

104

Carbon Dioxide Capture and Conversion

phosgene-derived diisocyanates. Alternatively, isocyanate-free productions of polyureas include the following: 1. trans-urethane polycondensation; 2. three-component coupling of PC and ethylenediamine with epoxy derivatives; 3. reaction of dicarbamates with diamines substantially explored over years (Krol, 2009; Suryawanshi et al., 2018). In a novel direction, the fixation of CO2 and diamines for PUs was also attempted by several strategies (Grignard et al., 2019); however, major concerns such as drastic reaction conditions as well as low molecular weights of resulting PUs were inevitable in these situations. For such reasons, improvements in the conversion of CO2 into PUs have been carried out with different catalytic systems (Muthuraj and Mekonnen, 2018). In the process, the practicality of superbase, i.e., DBU, in promoting the addition of CO2 to diamines was first proposed by Wu et al. (2019), in which the presence of DBU helped enhance the reaction rate of CO2 insertion as well as the molecular weight of the resulting polyureas. Mechanistically, the pathway leading to PUs from diamines and CO2 under the catalysis of DBU is proposed to follow through the coupling of in-situ generated isocyanate and diamine, which looks identical to the carboxylation of monoamines and CO2 into 1,3-DSUs. Along with polyureas, another important class of polymeric materials derived from waste CO2 is polycarbonates, where numerous synthetic strategies related to the direct coupling of CO2 with epoxides, diols, and diols with dihalides have been investigated (Chen et al., 2016; Wang and Darensbourg, 2018; Gu et al., 2019). Taking advantage of the usefulness of a reversible system composed of CO2
alcohol
organic superbase, Chai et al. (2020) suggested a versatile pattern to manufacture a broad library of CO2-based polycarbonates through the thiol-iene click or acyclic diene metathesis (ADMET) polymerization. Initially, several diols were carboxylated with CO2 over a stoichiometric amount of TMG, which underwent room-temperature coupling with allyl bromide to provide functionalized α,ω-diene and α,ω-mono-ene carbonate monomers, respectively. Subsequently, these monomers were subjected to the polymerization through the metal-free thiol-ene click or ADMET procedure, where novel poly(thioether carbonates) or unsaturated aromatic-aliphatic polycarbonates with high molecular weights (Mn: 2500
45,500) and satisfactory thermal properties (Td max: 233°C
375°C) were successfully engineered. Besides, the post-modification of these resulting polymers via

Organic base-mediated fixation of CO2 into value-added chemicals

105

the oxidation or hydrogenation resulted in poly(sulfone carbonates) or saturated aromatic
aliphatic polycarbonates, respectively.

5.2.5 CO2 reduction-derived products With the aim of tackling obvious drawbacks (e.g., high pressure, stoichiometric loading of bases, metal catalysts, and organic solvents) during the production of N-formamides from CO2, amines and H2, Das Neves Gomes et al. (2012) reported an alternative approach involving the employment of phenylsilane (PhSiH3) as a benign reducing agent. Under the solvent- and metal-free condition, a wide range of N-formamides could be achieved in the yield range of 24%
100% over 5 mol% of TBD depending on the structure and basicity of starting amines. Li et al. (2018) deployed polymethylhydrosiloxane (PMHS), a lowcost and abundant waste in the silicone industry, as a replacement for expensive phenylsilane in the reduction of CO2. To this end, the reductive coupling of amines and PMHS with CO2 was carried out in CH3CN under the catalysis of DBU, where the selective formation of either Nformamides or N-methylamines could be controlled by proper reaction conditions (e.g., temperature, reaction time, and catalyst loading). For instance, N-methylamines were dominantly generated upon performing the reduction for 48 h at 100°C with 1 mol% of DBU. Meanwhile, the N-formylation reaction at 30°C required an extension of timescale (B72 h) and a higher loading of DBU (B10 mol%). However, this switchable paradigm was only compatible with secondary aliphatic amines because neither N-formamides nor N-methylamines were detected upon starting with anilines under optimal conditions. In comparison with other organic bases such as Et3N, DABCO, DMAP, DIPEA, and DBN, the superior activity of DBU was attributed to its unique framework and high nucleophilicity. Regarding the suggested mechanism, the reductive fixation of CO2 into either N-formamides or N-methylamines from PMHS and amines under the promotion of DBU initially involved with the generation of CO2
DBU adduct. Subsequent interaction of this reactive species with PMHS followed by the hydrogen transfer produced the silyl formate intermediate. At this stage, N-formamides would be generated from the DBU-mediated coupling of silyl formate with amines. Concurrently, silyl formate was further transformed into bis(silyl)acetal and readily coupled with amines and

106

Carbon Dioxide Capture and Conversion

PHMS in the presence of DBU to give the final product of Nmethylamines. Nicholls et al. (2018) investigated the reductive animation of CO2 with silanes under the catalysis of simple TMG. Through the model test of morpholine, the authors found that the reaction could happen in different pathways to furnish morpholine-derived products of N-formamide (1), N-methylamine (2), and aminal (3) depending on the reaction temperature. Typically, room temperature selectively induced the formation of (1), while the generation of (2) and (3) was achieved at high temperatures (B60°C). Furthermore, the TMG-assisted reduction of (3) with CO2 at room temperature gave an equimolar mixture of (1) and (2). These results indicated that high selectivity of the resulting products, i.e., N-formamides, N-methylamines, and aminals, could be achieved by properly governing the mechanistic pathways. Regrettably, TMG could undergo self-formylation, resulting in catalytic deactivation for the next cycle. To overcome this inevitable drawback, the authors suggested that the alkylation of TMG would be beneficial in enhancing the stability and activity with respect to the original TMG, thereby delivering the apex TON value of 805 in the domain of CO2 reduction with 0.1 mol% loadings. Besides, the four-electron reductive coupling of CO2, secondary aromatic amines, and PhSiH3 promoted by TBD was reported to trigger the major formation of aminal products under a mild condition (Frogneux et al., 2015). In the presence of 5 mol% of TBD (Fig. 5.3A), the metalfree hydrosilylation of CO2 involved the catalytic cleavage of C
O bonds from CO2 along with the simultaneous assembly of C
H and C
N bonds, finally leading to a broad collection of symmetrical and unsymmetrical aminals (yield: 14%
99%). Interestingly, this reductive methodology also allowed for the methylenation of diethylmalonate with CO2, giving an yield of 58% of the corresponding product. For a deep insight into the TBD-mediated reductive coupling of amines, hydrosilane with CO2, Zhang et al. (2018b) employed the DFT calculations to investigate the impact of amines and solvents on the mechanistic access toward N-formamide, N-methylamine, or aminal products. Based on computational results, it is established that aliphatic amines with strong nucleophilicity dominantly provided N-formamides, while aromatic amines tended to render N-methylamines or aminals. In addition, two different mechanistic pathways (neutral versus anionic) were also observed depending on the polarity of solvents and reaction temperature. Specifically, the neutral mechanism would take place in a weak polar

Organic base-mediated fixation of CO2 into value-added chemicals

107

Figure 5.3 (A) TBD-mediated synthesis of aminals from CO2, amines, and PhSiH3, and (B) synthesis of CO2-derived methoxysilanes over a phosphazene catalyst.

solvent, i.e., THF, at 100°C to give N-formamides. Conversely, a strong polar solvent such as CH3CN strongly favored the yielding of aminals and N-methylamines at 80°C. Apart from cyclic guanidines, phosphazene superbase (1) was also investigated for the hydrosilylation of CO2 (Courtemanche et al., 2015). During the transformation, it is verified that the conversion of (1) into the corresponding oxide through the insertion of CO2 facilitated the reduction. The selectivity toward methoxysilanes and silyl formate from CO2 and diphenylsilane (Ph2SiH2) could be controlled by the reaction

108

Carbon Dioxide Capture and Conversion

condition. As shown in Fig. 5.3B, silyl formate was preferentially generated in comparison with silylacetal and methoxysilanes when Ph2SiH2 was treated with CO2 and 1.25 mol% of (1) in DMF in the first stage. A complete conversion of silyl formate into methoxysilanes was achieved with the external addition of Ph2SiH2. Indeed, this simple protocol allowed for the hydrosilylation to yield a TON and TOF value of 759 and 32/h, respectively. Encouraged by the successful formation of N-formamides from the organic base-mediated hydrosilylation of CO2, Das Neves Gomes et al. (2014) suggested that various superbases such as TBD, mTBD, and DBU were likely to facilitate the hydroboration of CO2 into methoxide compounds. By treating the mixture of CO2 and reactive hydroboranes (9BBN and catBH) with mTBD at room temperature in THF, the authors achieved methoxyborane derivative (CH3OBR2) with maximum values of TON (648) and TOF (33/h). The resulting CH3OBR2 was subjected to aqueous hydrolysis to give a quantitative yield of CH3OH. Legare et al. (2014) reported the application of borane
dimethylsulfide (BH3  SMe2) as an alternative reducing agent for the reduction of CO2. In contrast to superbases such as DBU and TMP, N,N,N0 ,N0 -tetramethyl-1,8-naphthalenediamine (DMAN) was demonstrated to outperform in the matter of activity for the hydroboration of CO2 into methoxyboranes, thereby yielding an unprecedented TOF value of 64/h. In the DMAN-mediated mechanism, BH3  SMe2 was activated in the first stage by bidentate amine to generate a reactive complex of boronium
borohydride [DMAN-BH2] [BH4] . This ionic pair reacted with CO2 to render BH3 and [DMAN-BH2] [HCOO] . To complete the catalytic cycle, DMAN was released along with the formation of formatoborane species (HCOOBH2). The reduction of HCOOBH2 by BH3  SMe2 took place to yield the target methoxyboranes. Motivated by this research, Sabet-Sarvestani et al. (2018) executed a theoretical investigation on the catalysis of proton sponge, i.e., quinolino [7,8-h]quinoline, in the reduction of CO2 and BH3 into methanol. Through the computational calculation on thermodynamic and kinetic parameters, quinolino[7,8-h]quinoline displayed supreme performance with respect to other types of proton sponges, attributed to the absence of steric effect around the nitrogen atoms. Zhang et al. (2018a) carried out the hydroboration of BH3NH3 with CO2 in the presence of TBD/ Et3N
CH3CN at 80°C to deliver well-defined derivatives of boryl formate. Further treatment of these in situ-generated species with external reagents resulted in corresponding formic acid, formates, formamides,

Organic base-mediated fixation of CO2 into value-added chemicals

109

secondary alcohol, and azole compounds with great success under mild conditions (Fig. 5.4).

5.2.6 Carboxylic acids and their ester derivatives Although there have been several attempts made to prepare salicylic acids directly from the Kolbe
Schmitt reaction of resorcinols and CO2 (Hessel et al., 2005; Shanthi and Palanivelu, 2015), the drawbacks of low yields, harsh conditions, and limited scope of substrates greatly hampered this synthetic direction. In an endeavor to develop a novel catalyst system for a milder production of salicylic acids, Sadamitsu et al. (2019) established that the room-temperature Kolbe
Schmitt carboxylation of resorcinols and CO2 could be carried out with no difficulty in the presence of DBU.

Figure 5.4 Organic base-mediated hydroboration of BH3NH3 with CO2.

110

Carbon Dioxide Capture and Conversion

By controlling the nature of substituents on resorcinol derivatives, only one isomer of salicylic acids in the yield range of 20%
99% was selectively generated under ambient conditions (30°C and 2 MPa of CO2). Through the in-situ H-NMR study, it is revealed that dianionic intermediate species derived from the treatment of resorcinols with 3 equivalents of DBU would only allow for the addition of CO2 at selective sites containing high distributions of electron density. Starting from CO2 and active methylene compounds (i.e., cyclohexanone, acetophenone, 1-indanone, indene, and fluorine), the roomtemperature syntheses of carboxylic acids in the presence of DBU were first carried out by Haruki et al. (1974) and Mori (1988). However, only low to moderate yields of corresponding carboxylic acids were accomplished with a high loading amount of DBU as a promoter. In another study, Flowers et al. (2008) established a sequential carboxylation
hydrogenation of ketones to prepare chiral β-hydroxycarboxylic acids from CO2. In the first stage, the solvent-free carboxylation of aliphatic/ aromatic ketones with CO2 (60 bar) was executed under the catalysis of DBU (2 equivalents) at 0°C to render a variety of β-ketocarboxylic acids, in which the yields of resulting β-ketocarboxylic acids were strongly dependent on the steric hindrance and hydrophilicity of the starting ketones. Subsequently, the asymmetric hydrogenation was carried out in methanol over an Ru(II) BINAP catalyst to obtain the highest yield and enantio-selectivity of β-hydroxycarboxylic acids. In comparison with classical approaches toward producing propiolic acids, the direct carboxylation of terminal alkynes with CO2 was demonstrated to take place under milder conditions with the involvement of transitional metal catalysts (Qiao et al., 2018). Although sensitive organometallic compounds (n-BuLi and Grignard reagents) could be eliminated in this CO2 transformation, a large consumption of inorganic bases and harmful complexes of transitional metals rendered major limitations. Wang et al. (2013) introduced an upgraded carboxylation of CO2 with either acetylene or terminal alkynes in the absence of any metals, inorganic salts, or organometallic reagents. In this study, TBD was acknowledged as the most appropriate organic base to render the active CO2 adduct (TBD
CO2) as well as to deprotonate alkynes, thus converting a wide variety of aliphatic, aromatic, and substituted alkyne derivatives with CO2 into corresponding carboxylic acids (yield: 41%
94%) at 100° C in DMAc. In some cases, the requirement of solvent for the transformation was not necessary depending on the nature of alkynes.

Organic base-mediated fixation of CO2 into value-added chemicals

111

Aside from alkylidene cyclic carbonates, the organic base-mediated coupling of propargylic alcohols with CO2 could deliver tetronic acid as the main product as well (Shen et al., 2018). In this manner, a 68% yield of 4-(4-hydroxy-5,5-dimethyl-2-oxo-2,5-dihydro-furan-3-yl)-benzonitrile was obtained upon heating 1 equivalent of 4-(3-hydroxy-3-methylbut-1-yn-1-yl)benzonitrile and CO2 (1 atm) with 4 equivalents of TBD in 1,3-dimethyl-2-imidazolidinone. Under identical conditions, no product was observed with DABCO, while DBU or MTBD gave poor yields of 19% or 31%, respectively.

5.2.7 Five-membered heterocycles To develop a convenient and simple catalytic system for benzimidazolones from the direct carboxylation of o-phenylenediamines with CO2, Brahmayya et al. (2017) found tributylamine (TBA) as an efficient catalyst. Apart from the availability and efficacy of TBA with respect to other benchmark catalysts (e.g., ionic liquids and ruthenium/tungsten complex), the reaction performed under solvent-free conditions is also another merit of this synthetic template. In this model, 70%
97% yields of benzimidazolone products could be obtained depending on the starting precursors under 0.2 equivalent of TBA. Significantly, this recyclable catalyst was also applicable to the fixation of CO2 into 2-aminophenol and 2aminobenzonitrile to deliver good and isolated yields of 2-benzoxazolone (60%) and quinazoline-2,4(1H, 3H)-dione (75%). Another catalyst system for the fixation of CO2 into benzimidazolone derivatives composed of an equimolar mixture of DBU
S8 was also developed by Cao et al. (2018). Through the DFT calculations upon performing the reaction in the presence of NMP as a solvent, the complexation of S8 with protonated species of DBU (DBUH derived from the interaction of DBU and NMP) was shown to enhance the reaction rate, thereby enabling the fixation of atmospheric CO2 to run smoothly at 140°C to produce 80%
94% yields of benzimidazolones. Gao et al. (2018) attempted to prepare a set of benzothiazolone derivatives from the organic base-mediated carbonylation of 2aminothiophenols with CO2 in NMP. In this method, a variety of commercial organic bases were evaluated, with their catalytic activity in the order of Mim (pKa 7.1) DABCO (pKa 8.7) TMG (pKa 23.3) DBU (pKa 24.3) TBD (pKa 26) DBN (pKa 23.8). Interestingly, the authors found that the superior catalytic performance of

112

Carbon Dioxide Capture and Conversion

DBN over tested bases was attributed to the perfect harmony between the basicity and the steric hindrance of DBN. To establish a greener approach toward benzothiazoles, Gao et al. (2014) introduced the application of DBN in the reductive cyclization of 2-aminothiophenols, CO2 with diethylsilane (Et2SiH2). The experimental results revealed that DBN with lower steric hindrance with respect to TBD and DBU could provide a better outcome of benzothiazoles under identical conditions. Additionally, Et2SiH2 established considerable importance in generating benzothiazoles by hampering the competitive formation of benzothiazolones. Therefore, this strategy could provide a library of benzothiazole derivatives from CO2 in an effective manner with no involvement of metal catalysts. As shown in Fig. 5.5, the organic base-mediated construction of azoles from CO2 could take place via two different mechanisms. In the case of benzimidazolones and benzothiazolones, the reaction occurred through a stepwise pattern, where isocyanate intermediates were in-situ generated and inducing cyclization (Path A). On the other hand, the reductive cyclization of CO2 and 2-aminothiophenols with Et2SiH2 into benzothiazoles

Figure 5.5 Suggested mechanisms leading to CO2-derived azoles over organic bases.

Organic base-mediated fixation of CO2 into value-added chemicals

113

involved the formation of formamide intermediates (Path B). Although a trace amount of benzothiazolones was inevitably generated from 2aminothiophenols and CO2, the subsequent conversion of this byproduct species into benzothiazoles was excluded in this pathway. By executing the dearomatization
carbonylation cascade over organic bases, Cerveri et al. (2019) were able to access the imidazo- and oxazolopyridinone framework from the one-pot dearomative carbonylation of pyridine derivatives with CO2. In this scenario, the authors selected the mixture of TBD
Et3N with a molarity of 1:5 as the optimal catalyst system upon heating pyridine-2-methanamines and acyl chlorides with CO2 in CH3CN at 140°C. As a result, several derivatives of imidazo- and oxazolo-pyridinones were achievable in high yield and regio-selectivity under redox-neutral and metal-free conditions. Noticeably, a broad family of pyridine amines/pyridyl alcohols and acyl chlorides could be operable in this synthetic paradigm. Through a set of experimental analyses (e.g., NMR, FTIR, and DFT calculation), the principal role of TBD as a Bronsted acid to activate both reagents and intermediates during this redox-neutral and metal-free transformation is delineated in Fig. 5.6. In this case, TBD was demonstrated to mediate the formation of zwitterionic species of IV from the insertion of acyl chloride into III. Meanwhile, Et3N was necessary for the deprotonation of IV into the final product along with the regeneration of TBD. Despite numerous efforts in the assembly of spiro-indolepyrrolidines and spiro-indolinepyrrolidines, the utilization of CO2 as a starting material for these skeletons has not yet been realized for several years (Bariwal et al., 2018). Recently, Zhu et al. (2017) successfully introduced a facile approach for spiro-indolepyrrolidines through the organic base-mediated dearomatization of tryptamine derivatives with CO2 and PhSiH3. It is revealed that the catalytic activity of these organic bases is in the order of pyridine DABCO DBU TBD. With the catalysis of 20% mol of TBD, the transitional metal-free tandem reaction starting from a broad scope of tryptamines could run smoothly in CH3CN at 100°C to give 55%
92% yields of spiro-indolepyrrolidine derivatives with good tolerance of functional groups. Noticeably, subsequent reduction of purified spiro- indolepyrrolidines over NaBH4 led to a collection of spiroindolinepyrrolidines in good diastereo-selectivity. In the mechanistic investigation on the tandem assembly of spiro-indolepyrrolidine, the new C
N bond was initially triggered from the coupling of tryptamine with bis(silyl)acetal derived from the TBD-induced reduction of CO2 and

114

Carbon Dioxide Capture and Conversion

Figure 5.6 The assembly of imidazo-pyridinones from CO2, pyridine-2-methanamines, and acyl chlorides over a binary system of TBD
Et3N.

PhSiH3. Later, the sequential generation of iminium intermediate and dearomatization led to the establishment of a new C
C bond, finally rendering spiro-indolepyrrolidine.

5.2.8 Six-membered heterocycles Most previous studies on the functionalization of indoles with CO2 involved the catalytic synthesis of indole-3-carboxylic acids from corresponding indoles in the presence of a Lewis acid (Nemoto et al., 2009) or a base (Yoo et al., 2012). During such transformations, a stoichiometric to an excessive amount of air/moisture-sensitive reagents (Me2AlCl and LiOtBu) was required to facilitate the selective carboxylation. In contrast, Xin et al. (2015) disclosed that 0.5
1 equivalent of TBD could attach CO2 with aliphatic/aromatic/heteroaromatic 2-alkylnyl indoles to provide 53%
86% isolated yields of tricyclic indole frameworks with high regioselectivity. Particularly, the metal-free transformation of various aromatic/ heteroaromatic/aliphatic 2-alkynyl indoles with different molecular complexities as well as upgraded scalability was achievable with a very low pressure of CO2 (5 equivalents). Unfortunately, neither alkyne-substituted electron-rich aryl nor heteroaryl ring systems were accomplished in this

Organic base-mediated fixation of CO2 into value-added chemicals

115

protocol. A detailed investigation of the mechanism illustrated that the TBDmediated transformation followed a series of steps in the following sequence: 1. CO2 activation by TBD through the zwitterionic adduct of CO2
TBD; 2. selective insertion of CO2
TBD species into C3 position of indoles; 3. deprotonation/rearomatization; 4. 6-endo-dig cyclization. 4-Hydroxy-2H-chromen-2-ones and 4-hydroxy-2(1 H)-quinolinones are important heterocyclic frameworks widely distributed in various products (Pratap and Ram, 2014). Conventionally, these privileged structures can be fabricated via the base-mediated cyclization or acid-induced Friedel
Crafts reactions (Ambre et al., 2013), where toxic wastes are of great concern to the environment. On the other hand, the first trial on the catalytic fixation of CO2 into 4-hydroxy-chromen-2-one derivatives was developed by Re and Sandri (1960). For this purpose, a variety of substituted o-hydroxyacetophenones were treated with CO2 (4 MPa) and K2CO3 in the temperature range of 130°C
170°C to provide 23%
63% yields of corresponding 4-hydroxy-chromen-ones. Zhang et al. (2015) replaced K2CO3 with DBU in this CO2-fixation pattern for a milder assembly of either 4-alkoxy-chromen-2-ones or 4alkoxy-1H-quinolin-2-ones. At a temperature of 80°C, 2 equivalents of DBU was sufficient in promoting the tandem carboxylation/cyclization/ alkylation of o-hydroxyacetophenones with CO2 (3 MPa) and n-butyl iodide (n-BuI) to result in 36%
87% isolated yields of corresponding 4butoxy-chromen-2-ones. Meanwhile, 4 equivalents of DBU was required for the carboxylation reaction of o-acetamidoacetophenones and methyl iodide (MeI), allowing for a complicated mixture of mono/di-methylated-2-quinolinones with a total isolated yield of up to 77%. Strikingly, this introduced methodology provided convenient access to valuable 4hydroxy-2H-chromen-2-ones and 4-hydroxy-2(1H)-quinolinones with respect to precedent protocols by hampering the decarboxylation during the work-up process. The tentative mechanism for the model carboxylation of o-acetamidoacetophenone (1) with CO2 through two different pathways is illustrated in Fig. 5.7. In Path A, an enolate I from the deprotonated species of (1) would undergo N-to-C acyl immigration, followed by a proton shifting to afford the enone intermediate (II). This resulting species would be converted into carboxylate (III) through the DBU-mediated insertion of CO2, which was subjected to the annulation or alkylation reaction to afford a methylated mixture of (II) and (III). Alternatively, the generation

116

Carbon Dioxide Capture and Conversion

Figure 5.7 DBU-medicated carboxylative cyclization of with CO2.

-acetamidoacetophenones

of this product mixture was also postulated from the sequence of CO2 insertion, carboxylative cyclization, N-to-C acyl immigration, or alkylation over enolate I (Path B). Quinazoline-2,4(1H,3H)-diones and their derivatives belong to the group of most valuable six-membered rings in nitrogen-containing heterocycles (Wang and Gao, 2013). Thanks to their versatile functionalities, a myriad of quinazoline-2,4(1H,3H)-diones have been widely deployed as synthetic templates in organic and medicinal chemistry (Russell et al., 1988; Michel et al., 1996). Conventionally, the manufacture of these heterocyclic frameworks involves the consumption of noxious reagents (e.g., phosgene, isocyanates, potassium cyanate, and CO) or requires optimum conditions (Vorbrüggen and Krolikiewicz, 1994; Tian et al., 2014). In contrast, a benign and sustainable paradigm toward quinazoline-2,4(1H,3H)-diones starting from CO2 and 2-aminobenzonitriles (2-ABNs) has gained the spotlight in the past few years, since the avoidance of toxic materials along with atom-economy

Organic base-mediated fixation of CO2 into value-added chemicals

117

enhancement was highly noticed in this paradigm. For that purpose, a variety of homogeneous/heterogeneous materials have been developed to facilitate this transformation, in which homogeneous basic catalysts were favorably selected. Table 5.1 illustrates the remarkable catalysis of organic bases/ superbases during the chemical fixation of CO2 and 2-ABNs into quinazoline-2,4(1H,3H)-diones. In these cases, a low amount of catalysts (0.05
0.2 equivalent) was able to convert CO2 and 2-ABNs into quinazoline-2,4(1H,3H)-dione derivatives with no difficulty, delivering moderate to quantitative isolated yields of cyclic products with high purity. Generally, the tentative mechanism of this CO2 conversion under the mediation of organic bases involved the initial generation of carbamate salt I from the carboxylation of 2-ABN with CO2. Subsequently, carboxylative cyclization of I into II, followed by the thermal rearrangement of II provided isocyanate species of III. At last, the annulation of III along with the stabilization of IV over organic bases occurred to render the final quinazoline-2,4(1H,3H)-dione (Fig. 5.8A). However, treating the DMF solution of 2-ABNs (1 equivalent) and DBU (3 equivalents) in atmospheric CO2 at room temperature delivered excellent yields of 2,4-dihydroxyquinazolines after acidic hydrolysis (Mizuno et al., 2000). In the case of 5-amino-4-cyanoimidazole, a harsh condition such as 30 atm and 120°C was required to deliver a 52% yield of xanthine. As illustrated in Fig. 5.8B, the DBU-mediated construction of 2,4-dihydroxyquinazolines from CO2 Table 5.1 Organic base-mediated synthesis of quinazoline-2,4-(1H, 3H)-diones from CO2 and 2-aminobenzonitriles. Bases

Reaction conditions

Isolated yield (%)

Reference

DBU (0.05
0.1 equivalent) DBU (0.1 equivalent) DBU (0.2 equivalent) TMG (0.05 equivalent) Melamine (0.1 equivalent) DEA (0.2 equivalent)

CO2 ( 0.1 MPa), DMF, 80°C, 24 h CO2 (10 MPa), 80°C, 4h CO2 ( 0.1 MPa), 150° C, 4 h CO2 (10 MPa), 120°C, 4h CO2 (4.2 MPa), H2O, 120°C, 18 h CO2 (1 MPa), H2O, 100°C, 12
24 h

82
98

Mizuno and Ishino (2002) Mizuno et al. (2004) Mizuno et al. (2007) Gao et al. (2010) Zhao et al. (2019) Sheng et al. (2020)

54
91 93
100 60
95 80
94 62
94

118

Carbon Dioxide Capture and Conversion

Figure 5.8 Organic base-mediated conversion of CO2 and 2-ABNs into (A) quinazoline-2,4(1H,3H)-diones; and (B) 2,4-dihydroxyquinazolines.

and 2-ABNs at room temperature follows a sequence of CO2 insertion, nucleophilic cyclization, and rearrangement, where the formation of isocyanate intermediates was ruled out.

Organic base-mediated fixation of CO2 into value-added chemicals

119

Previously, most CO2-to-cyclic anhydride transformations were implemented in the presence of metal catalysts. For example, maleic anhydrides could be produced either from the coupling of internal alkynes with CO and CO2 over a PdI2
KI catalyst (Gabriele et al., 1999) or from the electrochemical decarboxylation of arylacetylenes with CO2 over Ni
Al electrodes (Yuan et al., 2008). Additionally, a multicomponent system of Ni(acac)2(bpy)
Zn
MgBr2 to induce the double carboxylation of internal alkynes and CO2 into maleic anhydrides was also established by Fujihara et al. (2014). In the case of isotonic anhydrides, Zhang et al. (2017) explored the Pdmediated carboxylative coupling of o-iodoanilines with CO and CO2. Motivated by the successful transformations of CO2 under metal-free conditions, Zhang et al. (2020) proposed that the carboxylative cyclization of 2butenoates with CO2 to produce glutaconic anhydrides could be realized in the presence of an organic superbase. At room temperature, treating various derivatives of 2-butenoate containing electron-deficient leaving groups (e.g., fluorophenoxide, trifluoromethylphenoxide, nitrophenoxide, etc.) and CO2 (1 atm) with 3 equivalents of DBU in CH3CN led to too good to excellent yields of anhydrides (68%
92%). Strikingly, this metal-free carboxylative cyclization also allowed for a straightforward and gram-scale approach to the production of important glutaconic anhydrides from CO2. Based on a set of control experiments and isotopic labeling 13CO2, a tentative mechanism leading to glutaconic anhydride from the addition of CO2 to model pentafluorophenyl 2-butenoate 1 is proposed in Fig. 5.9. Initially, CO2 was readily captured by DBU to generate the DBU
CO2 complex at room temperature. Meanwhile,

Figure 5.9 DBU-mediated synthesis of gluconic anhydrides from CO2 and 2butenoates.

120

Carbon Dioxide Capture and Conversion

the substituted vinylketene I derived from the interaction of DBU and 1 was further transformed into DBU
dienolate adduct of II. Later, the DBU
CO2 complex would be inserted into II, followed by the annulation of III to provide the final glutaconic anhydride.

5.3 Conclusions Undoubtedly, CO2 has proven to be one of the most promising building blocks in synthetic chemistry by virtue of its abundance, low cost, and nontoxicity. However, it is challenging to convert CO2 into valuable chemicals and fuels under mild and green conditions due to the kinetic inertness and thermodynamic stability of this molecule. To address these limitations, several advancements in catalysis have been made to induce the efficient activation of CO2. Here, a holistic summary on the practicality of homogeneous organic bases for the fixation of CO2 into value-added chemicals such as urea, carbamates, carbonates, polyureas, polycarbonates, carboxylic acid derivatives, methanol, and heterocycles was given. In those examples, CO2 was successfully employed as a C1 surrogate for hazardous reagents (i.e., phosgene derivatives, isocyanates, and CO) in conventional synthetic approaches, thereby avoiding to a great extent risks to both human health and the environment during the work-up processes. As compared with other benchmark organocatalysts in CO2 fixation, organic bases displayed excellence in terms of activity, simplicity, and commercial availability. In another aspect, the outstanding catalysis of these organic bases enabled the conversion of CO2 and a broad scope of starting reagents under very mild conditions (e.g., room temperature, low pressure of CO2, free solvents), thereby producing various products with excellent tolerance and functionality. Moreover, most of these basic catalysts proved to be robust and recyclable after several trials with no loss of activity. This organic base-mediated strategy would provide an effective and eco-friendly means of utilizing waste or natural CO2, thereby considerably contributing to the mitigation of CO2 emission as well as the development of green and sustainable chemistry in the future.

References Ambre, P.K., Pissurlenkar, R.R.S., Wavhale, R.D., Shaikh, M.S., Khedkar, V.M., Wan, B., et al., 2013. Design, synthesis, and evaluation of 4-(substituted)phenyl-2-thioxo3,4-dihydro-1H-chromino[4,3-d]pyrimidin-5-one and 4-(substituted)phenyl-3,4dihydro-1H-chromino[4,3-d]pyrimidine-2,5-dione analogs as antitubercular agents. Medicinal Chemistry Research 23 (5), 2564
2575.

Organic base-mediated fixation of CO2 into value-added chemicals

121

Bariwal, J., Voskressensky, L.G., Van der Eycken, E.V., 2018. Recent advances in spirocyclization of indole derivatives. Chem Society Reviews 47 (11), 3831
3848. Brahmayya, M., Dai, S.A., Suen, S.Y., 2017. Facile synthesis of 2-benzimidazolones via carbonylation of o-phenylenediamines with CO2. Journal of CO2 Utilization 22, 135
142. Brege, A., Méreau, R., McGehee, K., Grignard, B., Detrembleur, C., Jerome, C., et al., 2020. The coupling of CO2 with diols promoted by organic dual systems: towards products divergence via benchmarking of the performance metrics. Journal of CO2 Utilization 38, 88
98. Buttner, H., Longwitz, L., Steinbauer, J., Wulf, C., Werner, T., 2017. Recent developments in the synthesis of cyclic carbonates from epoxides and CO2. Topic in Current Chemistry 375 (3), 50. Ca, N.D., Gabriele, B., Ruffolo, G., Veltri, L., Zanetta, T., Costa, M., 2011. Effective guanidine-catalyzed synthesis of carbonate and carbamate derivatives from propargyl alcohols in supercritical carbon dioxide. Advanced Synthesis & Catalysis 353 (1), 133
146. Cao, X., Zhong, H.A., Zhang, P., Zheng, H., 2018. The simple system of fixing CO2 to synthesize benzimidazolones at atmospheric pressure. Journal of CO2 Utilization 24, 250
255. Cerveri, A., Pace, S., Monari, M., Lombardo, M., Bandini, M., 2019. Redox-neutral metalfree three-component carbonylative dearomatization of pyridine derivatives with CO2. Chemistry (Weinheim an der Bergstrasse, Germany) 25 (67), 15272
15276. Chai, Y., Chen, Q., Huang, C., Zheng, Q., North, M., Xie, H., 2020. Introducing the reversible chemistry of CO2 with diols mediated by organic superbases into polycarbonate synthesis. Green Chemistry 22 (15), 4871
4877. Chaturvedi, D., 2011. Recent developments on the carbamation of amines. Current Organic Chemistry 15 (10), 1593
1624. Chaturvedi, D., Chaturvedi, K., Mishra, V., A., 2012. Carbon dioxide: versatile, cheap and safe alternative in the syntheses of organic carbamates. Current Organic Chemistry 16 (13), 1609
1635. Chen, Z., Hadjichristidis, N., Feng, X., Gnanou, Y., 2016. Cs2CO3-promoted polycondensation of CO2 with diols and dihalides for the synthesis of miscellaneous polycarbonates. Polymer Chemistry 7 (30), 4944
4952. Cho, W., Shin, M.S., Hwang, S., Kim, H., Kim, M., Kim, J.G., et al., 2016. Tertiary amines: a new class of highly efficient organocatalysts for CO2 fixations. Journal of Industrial and Engineering Chemistry 44, 210
215. Costa, M., Chiusoli, G.P., Taffurelli, D., Dalmonego, G., 1998. Superbase catalysis of oxazolidin-2-one ring formation from carbon dioxide and prop-2-yn-1-amines under homogeneous or heterogenous conditions. Journal of the Chemical Society, Perkin Transactions 1 (9), 1541
1546. Courtemanche, M.A., Legare, M.A., Rochette, E., Fontaine, F.G., 2015. Phosphazenes: efficient organocatalysts for the catalytic hydrosilylation of carbon dioxide. Chemical Communications 51 (31), 6858
6861. Das Neves Gomes, C., Jacquet, O., Villiers, C., Thuéry, P., Ephritikhine, M., Cantat, T., 2012. A diagonal approach to chemical recycling of carbon dioxide: organocatalytic transformation for the reductive functionalization of CO2. Angewandte Chemie International Edition 124 (1), 191
194. Das Neves Gomes, C., Blondiaux, E., Thuery, P., Cantat, T., 2014. Metal-free reduction of CO2 with hydroboranes: two efficient pathways at play for the reduction of CO2 to methanol. Chemistry (Weinheim an der Bergstrasse, Germany) 20 (23), 7098
7106. Eghbali, N., Li, C.J., 2007. Conversion of carbon dioxide and olefins into cyclic carbonates in water. Green Chemistry 9 (3), 213
215.

122

Carbon Dioxide Capture and Conversion

Flowers, B.J., Gautreau-Service, R., Jessop, P.G., 2008. β-Hydroxycarboxylic acids from simple ketones by carboxylation and asymmetric hydrogenation. Advanced Synthesis & Catalysis 350 (18), 2947
2958. Franz, M., Stalling, T., Steinert, H., Martens, J., 2018. First catalyst-free CO2 trapping of N-acyliminium ions under ambient conditions: sustainable multicomponent synthesis of thia- and oxazolidinyl carbamates. Organic & Biomolecular Chemistry 16 (37), 8292
8304. Frogneux, X., Blondiaux, E., Thuéry, P., Cantat, T., 2015. Bridging amines with CO2: organocatalyzed reduction of CO2 to aminals. ACS Catalysis 5 (7), 3983
3987. Fujihara, T., Horimoto, Y., Mizoe, T., Sayyed, F.B., Tani, Y., Terao, J., et al., 2014. Nickel-catalyzed double carboxylation of alkynes employing carbon dioxide. Organic Letters 16 (18), 4960
4963. Gabriele, B., Salerno, G., Costa, M., Chiusoli, G.P., 1999. Palladium-catalysed formation of maleic anhydrides from CO, CO2 and alk-1-ynes. Chemical Communications 15, 1381
1382. Galliani, G., Rindone, B., Saliu, F., 2009. Synthesis of 3-alkyloxazolidin-2,4-diones using 2-chloroacetamides, carbon dioxide and 1,8-diazabicyclo[5.4.0]undecene (DBU). Tetrahedron Letters 50 (36), 5123
5125. Gao, J., He, L.N., Miao, C.X., Chanfreau, S., 2010. Chemical fixation of CO2: efficient synthesis of quinazoline-2,4(1H, 3H)-diones catalyzed by guanidines under solventfree conditions. Tetrahedron 66 (23), 4063
4067. Gao, X., Yu, B., Zhao, Y., Hao, L., Liu, Z., 2014. Hydrosilane-promoted cyclization of 2aminothiophenols by CO2 to benzothiazoles. RSC Advances 4 (100), 56957
56960. Gao, X., Deng, Y., Lu, C., Zhang, L., Wang, X., Yu, B., 2018. Organic base-catalyzed C
S bond construction from CO2: a new route for the synthesis of benzothiazolones. Catalysts 8 (7), 271. Garcia-Egido, E., Fernandez-Suarez, M., Munoz, L., 2008. Synthesis of carbamoyl azides from primary amines and carbon dioxide under mild conditions. The Journal of Organic Chemistry 73 (7), 2909
2911. Ghosh, A.K., Brindisi, M., 2015. Organic carbamates in drug design and medicinal chemistry. Journal of Medicinal Chemistry 58 (7), 2895
2940. Gregory, G.L., Ulmann, M., Buchard, A., 2015. Synthesis of 6-membered cyclic carbonates from 1,3-diols and low CO2 pressure: a novel mild strategy to replace phosgene reagents. RSC Advances 5 (49), 39404
39408. Grignard, B., Gennen, S., Jerome, C., Kleij, A.W., Detrembleur, C., 2019. Advances in the use of CO2 as a renewable feedstock for the synthesis of polymers. Chemical Society Reviews 48 (16), 4466
4514. Gu, Y., Matsuda, K., Nakayama, A., Tamura, M., Nakagawa, Y., Tomishige, K., 2019. Direct synthesis of alternating polycarbonates from CO2 and diols by using a catalyst system of CeO2 and 2-furonitrile. ACS Sustainable Chemistry & Engineering 7 (6), 6304
6315. Haruki, E., Arakawa, M., Matsumura, N., Otsuji, Y., Imoto, E., 1974. Carboxylation of active methylene compounds using the reagent of 1,8-diazabicyclo(5.4.0)-7-undecene and carbon dioxide. Chemistry Letters 3 (5), 427
428. Heldebrant, D.J., Koech, P.K., Ang, M.T.C., Liang, C., Rainbolt, J.E., Yonker, C.R., et al., 2010. Reversible zwitterionic liquids, the reaction of alkanol guanidines, alkanol amidines, and diamines with CO2. Green Chemistry 12 (4), 713. Hessel, V., Hofmann, C., Löb, P., Löhndorf, J., Löwe, H., Ziogas, A., 2005. Aqueous Kolbe Schmitt synthesis using resorcinol in a microreactor laboratory rig under high-p,T conditions. Organic Process Research & Development 9 (4), 479
489. Howarth, G.A., 2003. Polyurethanes, polyurethane dispersions and polyureas: past, present and future. Surface Coatings International Part B: Coatings Transactions 86 (2), 111
118.

Organic base-mediated fixation of CO2 into value-added chemicals

123

Ishikawa, T., 2009. Superbases for Organic Synthesis: Guanidines, Amidines, Phosphazenes and Related Organocatalysts, Wiltshire. Wiley. Khokarale, S.G., Mikkola, J.P., 2019. Metal free synthesis of ethylene and propylene carbonate from alkylene halohydrin and CO2 at room temperature. RSC Advances 9 (58), 34023
34031. Kim, H.G., Lim, C.S., Kim, D.W., Cho, D.H., Lee, D.K., Chung, J.S., 2017. Multifunctional alkanolamine as a catalyst for CO2 and propylene oxide cycloaddition. Molecular Catalysis 438, 121
129. Krol, P., 2009. Polyurethanes
a review of 60 years of their syntheses and applications. Polimery 54 (07/08), 489
500. Legare, M.A., Courtemanche, M.A., Fontaine, F.G., 2014. Lewis base activation of borane-dimethylsulfide into strongly reducing ion pairs for the transformation of carbon dioxide to methoxyboranes. Chemical Communications 50 (77), 11362
11365. Li, Q., Wang, P., Liu, S., Fei, Y., Deng, Y., 2016. Catalytic degradation of polyurea: synthesis of N-substituted carbamates with CuO
ZnO as the catalyst. Green Chemistry 18 (22), 6091
6098. Li, G., Chen, J., Zhu, D.Y., Chen, Y., Xia, J.B., 2018. DBU-catalyzed selective Nmethylation and N-formylation of amines with CO2 and polymethylhydrosiloxane. Advanced Synthesis & Catalysis 360 (12), 2364
2369. Li, M., Abdolmohammadi, S., Hoseininezhad-Namin, M.S., Behmagham, F., Vessally, E., 2020. Carboxylative cyclization of propargylic alcohols with carbon dioxide: a facile and Green route to α-methylene cyclic carbonates. Journal of CO2 Utilization 38, 220
231. Liu, Q., Wu, L., Jackstell, R., Beller, M., 2015. Using carbon dioxide as a building block in organic synthesis. Nature Communications 6, 5933. Mac Dowell, N., Fennell, P.S., Shah, N., Maitland, G.C., 2017. The role of CO2 capture and utilization in mitigating climate change. Nature Climate Change 7 (4), 243
249. Manaka, Y., Nagatsuka, Y., Motokura, K., 2020. Organic bases catalyze the synthesis of urea from ammonium salts derived from recovered environmental ammonia. Scientific Reports 10 (1), 2834. Marchegiani, M., Nodari, M., Tansini, F., Massera, C., Mancuso, R., Gabriele, B., et al., 2017. Urea derivatives from carbon dioxide and amines by guanidine catalysis: easy access to imidazolidin-2-ones under solvent-free conditions. Journal of CO2 Utilization 21, 553
561. McGhee, W.D., Pan, Y., Riley, D.P., 1994. Highly selective generation of urethanes from amines, carbon dioxide and alkyl chlorides. Journal of the Chemical Society, Chemical Communications 6, 699. McGhee, W., Riley, D., Christ, K., Pan, Y., Parnas, B., 1995. Carbon dioxide as a phosgene replacement: synthesis and mechanistic studies of urethanes from amines, CO2, and alkyl chlorides. The Journal of Organic Chemistry 60 (9), 2820
2830. McGuire, T.M., López-Vidal, E.M., Gregory, G.L., Buchard, A., 2018. Synthesis of 5- to 8-membered cyclic carbonates from diols and CO2: a one-step, atmospheric pressure and ambient temperature procedure. Journal of CO2 Utilization 27, 283
288. Michel, J., Toulme, J.J., Vercauteren, J., Moreau, S., 1996. Quinazoline-2,4(1H,3H)dione as a substitute for thymine in triple-helix forming oligonucleotides: a reassessment. Nucleic Acids Research 24 (6), 1127
1135. Mizuno, T., Ishino, Y., 2002. Highly efficient synthesis of 1H-quinazoline-2,4-diones using carbon dioxide in the presence of catalytic amount of DBU. Tetrahedron 58 (16), 3155
3158. Mizuno, T., Okamoto, N., Ito, T., Miyata, T., 2000. Synthesis of 2,4-dihydroxyquinazolines using carbon dioxide in the presence of DBU under mild conditions. Tetrahedron Letters 41 (7), 1051
1053.

124

Carbon Dioxide Capture and Conversion

Mizuno, T., Iwai, T., Ishino, Y., 2004. The simple solvent-free synthesis of 1Hquinazoline-2,4-diones using supercritical carbon dioxide and catalytic amount of base. Tetrahedron Letters 45 (38), 7073
7075. Mizuno, T., Mihara, M., Nakai, T., Iwai, T., Ito, T., 2007. Solvent-free synthesis of quinazoline-2,4(1H,3H)-diones using carbon dioxide and a catalytic amount of DBU. Synthesis 2007 (16), 2524
2528. Mori, H., 1988. Mechanism of the carboxylation of cyclohexanone with carbon dioxide catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene. Bulletin of the Chemical Society of Japan 61 (2), 435
439. Muñoz, L., Paz, J., Pérez-Balado, C., Iglesias, B., 2009. Carbonylation with CO2 and phosphorus electrophiles: a convenient method for the synthesis of 2-oxazolidinones from 1,2-amino alcohols. Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry 2009 (03), 395
398. Muthuraj, R., Mekonnen, T., 2018. Recent progress in carbon dioxide (CO2) as feedstock for sustainable materials development: co-polymers and polymer blends. Polymer 145, 348
373. Nemoto, K., Onozawa, S., Egusa, N., Morohashi, N., Hattori, T., 2009. Carboxylation of indoles and pyrroles with CO2 in the presence of dialkylaluminum halides. Tetrahedron Letters 50 (31), 4512
4514. Nicholls, R.L., McManus, J.A., Rayner, C.M., Morales-Serna, J.A., White, A.J.P., Nguyen, B.N., 2018. Guanidine-catalyzed reductive amination of carbon dioxide with silanes: switching between pathways and suppressing catalyst deactivation. ACS Catalysis 8 (4), 3678
3687. Ochoa-Gómez, J.R., Gómez-Jiménez-Aberasturi, O., Ramírez-López, C.A., NietoMestre, J., Maestro-Madurga, B., Belsué, M., 2011. Synthesis of glycerol carbonate from 3-chloro-1,2-propanediol and carbon dioxide using triethylamine as both solvent and CO2 fixation
activation agent. Chemical Engineering Journal 175, 505
511. Otto, A., Grube, T., Schiebahn, S., Stolten, D., 2015. Closing the loop: captured CO2 as a feedstock in the chemical industry. Energy & Environmental Science 8 (11), 3283
3297. Ozaki, S., 1972. Recent advances in isocyanate chemistry. Chemical Reviews 72 (5), 457
496. Parker, H.L., Sherwood, J., Hunt, A.J., Clark, J.H., 2014. Cyclic carbonates as green alternative solvents for the heck reaction. ACS Sustainable Chemistry & Engineering 2 (7), 1739
1742. Paz, J., Perez-Balado, C., Iglesias, B., Munoz, L., 2010. Carbon dioxide as a carbonylating agent in the synthesis of 2-oxazolidinones, 2-oxazinones, and cyclic ureas: scope and limitations. The Journal of Organic Chemistry 75 (9), 3037
3046. Pérez, E.R., da Silva, M.O., Costa, V.C., Rodrigues-Filho, U.P., Franco, D.W., 2002. Efficient and clean synthesis of N-alkyl carbamates by transcarboxylation and Oalkylation coupled reactions using a DBU
CO2 zwitterionic carbamic complex in aprotic polar media. Tetrahedron Letters 43 (22), 4091
4093. Pratap, R., Ram, V.J., 2014. Natural and synthetic chromenes, fused chromenes, and versatility of dihydrobenzo[h]chromenes in organic synthesis. Chemical Reviews 114 (20), 10476
10526. Pulla, S., Felton, C.M., Ramidi, P., Gartia, Y., Ali, N., Nasini, U.B., et al., 2013. Advancements in oxazolidinone synthesis utilizing carbon dioxide as a C1 source. Journal of CO2 Utilization 2, 49
57. Qiao, J., Amirkhizi, A.V., Schaaf, K., Nemat-Nasser, S., Wu, G., 2011. Dynamic mechanical and ultrasonic properties of polyurea. Mechanics of Materials 43 (10), 598
607. Qiao, C., Cao, Y., He, L.N., 2018. Transition metal-catalyzed carboxylation of terminal alkynes with CO2. Mini-Reviews in Organic Chemistry 15 (4), 283
290.

Organic base-mediated fixation of CO2 into value-added chemicals

125

Re, P.D., Sandri, E., 1960. Über eine neue synthese der 4-hydroxy-cumarine. Chemische Berichte 93 (5), 1085
1088. Roshan, K.R., Kim, B.M., Kathalikkattil, A.C., Tharun, J., Won, Y.S., Park, D.W., 2014. The unprecedented catalytic activity of alkanolamine CO2 scrubbers in the cycloaddition of CO2 and oxiranes: a DFT endorsed study. Chemical Communications 50 (89), 13664
13667. Russell, R.K., Press, J.B., Rampulla, R.A., McNally, J.J., Falotico, R., Keiser, J.A., et al., 1988. Thiophene systems. 9. Thienopyrimidinedione derivatives as potential antihypertensive agents. Journal of Medicinal Chemistry 31 (9), 1786
1793. Sabet-Sarvestani, H., Izadyar, M., Eshghi, H., Noroozi-Shad, N., Bakavoli, M., 2018. Proton sponge as a new efficient catalyst for carbon dioxide transformation to methanol: theoretical approach. Fuel 221, 491
500. Sadamitsu, Y., Okumura, A., Saito, K., Yamada, T., 2019. Kolbe-Schmitt type reaction under ambient conditions mediated by an organic base. Chemical Communication 55 (66), 9837
9840. Sakakura, T., Kohno, K., 2009. The synthesis of organic carbonates from carbon dioxide. Chemical Communication 11, 1312
1330. Sakakura, T., Choi, J.C., Yasuda, H., 2007. Transformation of carbon dioxide. Chemical Reviews 107 (6), 2365
2387. Shaikh, A.A., Sivaram, S., 1996. Organic carbonates. Chemical Reviews 96 (3), 951
976. Shang, J., Liu, S., Ma, X., Lu, L., Deng, Y., 2012. A new route of CO2 catalytic activation: syntheses of N-substituted carbamates from dialkyl carbonates and polyureas. Green Chemistry 14 (10), 2899. Shang, Y., Zheng, M., Zhang, H., Zhou, X., 2019. The guanidine-promoted direct synthesis of open-chained carbonates. Australian Journal of Chemistry 72 (12), 933. Shanthi, B., Palanivelu, K., 2015. Conversion of carbon dioxide to resorcylic acid under ultrasonication by Kolbe-Schmitt reaction. Ultrasonics Sonochemistry 27, 268
276. Shen, G., Zhou, W.J., Zhang, X.B., Cao, G.M., Zhang, Z., Ye, J.H., et al., 2018. Synthesis of tetronic acids from propargylic alcohols and CO2. Chemical Communications 54 (44), 5610
5613. Sheng, Z.Z., Huang, M.M., Xue, T., Xia, F., Wu, H.H., 2020. Alcohol amine-catalyzed CO2 conversion for the synthesis of quinazoline-2,4-(1H,3H)-dione in water. RSC Advances 10 (57), 34910
34915. Song, Q.W., Zhou, Z.H., He, L.N., 2017. Efficient, selective and sustainable catalysis of carbon dioxide. Green Chemistry 19 (16), 3707
3728. Sun, J., Liang, L., Sun, J., Jiang, Y., Lin, K., Xu, X., et al., 2010. Direct synthetic processes for cyclic carbonates from olefins and CO2. Catalysis Surveys from Asia 15 (1), 49
54. Suryawanshi, Y., Sanap, P., Wani, V., 2018. Advances in the synthesis of non-isocyanate polyurethanes. Polymer Bulletin 76 (6), 3233
3246. Taylor, J.E., Bull, S.D., Williams, J.M.J., 2012. Amidines, isothioureas, and guanidines as nucleophilic catalysts. Chemical Society Reviews 41 (6), 2109. Tian, X.C., Huang, X., Wang, D., Gao, F., 2014. Eco-efficient one-pot synthesis of quinazoline-2,4(1H,3H)-diones at room temperature in water. Chemical and Pharmaceutical Bulletin 62 (8), 824
829. Truong, C.C., Mishra, D.K., 2020. Recent advances in the catalytic fixation of carbon dioxide to value-added chemicals over alkali metal salts. Journal of CO2 Utilization 41, 101252. Vorbrüggen, H., Krolikiewicz, K., 1994. The introduction of nitrile-groups into heterocycles and conversion of carboxylic groups into their corresponding nitriles with chlorosulfonylisocyanate and triethylamine. Tetrahedron 50 (22), 6549
6558. Wang, D., Gao, F., 2013. Quinazoline derivatives: synthesis and bioactivities. Chemistry Central Journal 7 (1), 95.

126

Carbon Dioxide Capture and Conversion

Wang, Y., Darensbourg, D.J., 2018. Carbon dioxide-based functional polycarbonates: metal catalyzed copolymerization of CO2 and epoxides. Coordination Chemistry Reviews 372, 85
100. Wang, C., Mahurin, S.M., Luo, H., Baker, G.A., Li, H., Dai, S., 2010. Reversible and robust CO2 capture by equimolar task-specific ionic liquid
superbase mixtures. Green Chemistry 12 (5), 870. Wang, X., Lim, Y.N., Lee, C., Jang, H.Y., Lee, B.Y., 2013. 1,5,7-Triazabicyclo[4.4.0] dec-1-ene-mediated acetylene dicarboxylation and alkyne carboxylation using carbon dioxide. European Journal of Organic Chemistry 2013 (10), 1867
1871. Wang, H., Deng, X., Wu, H., Pi, A., Li, J., Huang, F., 2019. Investigating the dynamic mechanical behaviors of polyurea through experimentation and modeling. Defence Technology 15 (6), 875
884. Wang, L., Que, S., Ding, Z., Vessally, E., 2020. Oxidative carboxylation of olefins with CO2: environmentally benign access to five-membered cyclic carbonates. RSC Advances 10 (15), 9103
9115. Webster, D.C., 2003. Cyclic carbonate functional polymers and their applications. Progress in Organic Coatings 47 (1), 77
86. Wu, J., Kozak, J.A., Simeon, F., Hatton, T.A., Jamison, T.F., 2014. Mechanism-guided design of flow systems for multicomponent reactions: conversion of CO2 and olefins to cyclic carbonates. Chemical Science 5 (3), 1227. Wu, P.X., Cheng, H.Y., Shi, R.H., Jiang, S., Wu, Q.F., Zhang, C., et al., 2019. Synthesis of polyurea via the addition of carbon dioxide to a diamine catalyzed by organic and inorganic bases. Advanced Synthesis & Catalysis 361 (2), 317
325. Xin, Z., Lescot, C., Friis, S.D., Daasbjerg, K., Skrydstrup, T., 2015. Organocatalyzed CO2 trapping using alkynyl indoles. Angewandte Chemie International Edition 54 (23), 6862
6866. Xu, M., Jupp, A.R., Ong, M.S.E., Burton, K.I., Chitnis, S.S., Stephan, D.W., 2019. Synthesis of urea derivatives from CO2 and silylamines. Angewandte Chemie International Edition 58 (17), 5707
5711. Yang, Z.Z., He, L.N., Zhao, Y.N., Li, B., Yu, B., 2011. CO2 capture and activation by superbase/polyethylene glycol and its subsequent conversion. Energy & Environmental Science 4 (10), 3971. Yoo, W.J., Capdevila, M.G., Du, X., Kobayashi, S., 2012. Base-mediated carboxylation of unprotected indole derivatives with carbon dioxide. Organic Letters 14 (20), 5326
5329. Yu, K.M.K., Curcic, I., Gabriel, J., Tsang, S.C.E., 2008. Recent advances in CO2 capture and utilization. ChemSusChem 1 (11), 893
899. Yuan, G.Q., Jiang, H.F., Lin, C., 2008. Efficient electrochemical dicarboxylations of arylacetylenes with carbon dioxide using nickel as the cathode. Tetrahedron 64 (25), 5866
5872. Zhang, W.Z., Liu, S., Lu, X.B., 2015. DBU-promoted carboxylative cyclization of ohydroxy- and o-acetamidoacetophenone. Beilstein Journal of Organic Chemistry 11, 906
912. Zhang, W.Z., Zhang, N., Sun, Y.Q., Ding, Y.W., Lu, X.B., 2017. Palladium-catalyzed cyclization reaction of o-Iodoanilines, CO2, and CO: access to isatoic anhydrides. ACS Catalysis 7 (12), 8072
8076. Zhang, B., Du, G., Hang, W., Wang, S., Xi, C., 2018a. Lewis base promoted reduction of CO2 with BH3NH3 into Boryl formates: CO2 as a carbon source in organic synthesis under mild conditions. European Journal of Organic Chemistry 2018 (14), 1739
1743. Zhang, C., Lu, Y., Zhao, R., Menberu, W., Guo, J., Wang, Z.X., 2018b. A comparative DFT study of TBD-catalyzed reactions of amines with CO2 and hydrosilane: the

Organic base-mediated fixation of CO2 into value-added chemicals

127

effect of solvent polarity on the mechanistic preference and the origins of chemoselectivities. Chemical Communications 54 (77), 10870
10873. Zhang, K., Zhang, W.Z., Tao, X.Y., Zhang, M., Ren, W.M., Lu, X.B., 2020. Carboxylative cyclization of 2-butenoates with carbon dioxide: access to glutaconic anhydrides. The Journal of Organic Chemistry 85 (17), 11579
11588. Zhao, B., Yao, S., An, H., Zhao, X., Wang, Y., 2014. One-pot synthesis of methylphenyl carbamate from aniline, carbon dioxide and methanol. Journal of Chemical Technology & Biotechnology 89 (10), 1553
1558. Zhao, Y., Qiu, J., Li, Z., Wang, H., Fan, M., Wang, J., 2017. An experimental and theoretical study on the unexpected catalytic activity of triethanolamine for the carboxylative cyclization of propargylic amines with CO2. ChemSusChem 10 (9), 2001
2007. Zhao, G.Y., Mu, L.L., Ullah, L., Wang, M., Li, H.P., Guan, X.X., 2019. CO2 involved synthesis of quinazoline-2,4(1H,3H)-diones in water using melamine as a thermoregulated catalyst. Canadian Journal of Chemistry 97 (3), 212
218. Zhou, X., Yang, X., Chen, T., Zhang, Y., Wang, G., 2009. Synthesis of propylene carbonate from carbon dioxide and o-chloropropanol. Chinese Journal of Catalysis 30 (1), 7
8. Zhou, H., Mu, S., Ren, B.H., Zhang, R., Lu, X.B., 2019. Organocatalyzed carboxylative cyclization of propargylic amides with atmospheric CO2 towards oxazolidine-2,4diones. Green Chemistry 21 (5), 991
994. Zhu, D.Y., Fang, L., Han, H., Wang, Y., Xia, J.B., 2017. Reductive CO2 fixation via tandem C-C and C-N bond formation: synthesis of spiro-indolepyrrolidines. Organic Letters 19 (16), 4259
4262.

CHAPTER 6

Catalytic conversion of CO2 into methanol Nor Hafizah Berahim and Noor Asmawati Mohd Zabidi Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak, Malaysia

Abbreviations ADP Al2O3 BET C10H10O4 C2H6O C3H6 C5H12O C5H8O2 CCS CCUS CDU CH3COOH CH3OH Cr2O3 Cr
CuB CuO DME DMT Fe2O3 GHSV GSV H2S HCHO HCO HCOO HRTEM LEIS MCF MCM-41 MgO MnO MTBE

ammonia-driving deposition
precipitation alumina Brunauer
Emmett
Teller dimethyl terephthalates dimethyl ether Propene methyl tertiary-butyl ether methyl methacrylate carbon capture and storage carbon capture, utilization, and storage carbon dioxide utilization acetic acid methanol chromium (III) oxide chromium
copper boron copper (II) oxide dimethyl ether dimethyl terephthalate iron (III) oxide gas hourly space velocity gas space velocity hydrogen sulfide formaldehyde formyl formate high-resolution transmission electron microscopy low-energy ion scattering mesostructured cellular foam mobil composition of matter no. 41 magnesium oxide manganese (II) oxide methyl tert-butyl ether

Carbon Dioxide Capture and Conversion DOI: https://doi.org/10.1016/B978-0-323-85585-3.00002-X

© 2022 Elsevier B.V. All rights reserved.

129

130

Carbon Dioxide Capture and Conversion

RWGS SBA-15 SiC SiO2 STY TEOS Th
CuB TMOS TOS TPOS TPR WGS WHSV WTY ZnO ZrO2

reverse water
gas shift Santa Barbara Amorphous
15 silicon carbide silicon dioxide space
time yield tetraethyl orthosilicate thorium
copper boron tetramethyl orthosilicate time on stream tetrapropyl orthosilicate temperature-programmed reduction water
gas shift weight hourly space velocity weight
time yield zinc oxide zirconium dioxide

6.1 Introduction Global warming and rapid climate change caused by the increase in greenhouse gases have attracted considerable attention from scientists and leaders worldwide. The increasing use of fossil fuels along with specific industrial activities, such as cement production, contributed to the constant increase in carbon dioxide (CO2) emission in the atmosphere. CO2, the primary greenhouse gas, is a significant contributor ( 60%) to the enhanced greenhouse effect. The rate of emission reaches 15 GT annually; thus, it is expected that by 2050, the temperature will increase by 2°C. The International Energy Agency has proposed numerous options for reducing CO2 so that the desired outcome of a temperature increase of less than 2°C can be achieved. These options include carbon capture and storage (CCS), sustainability in the primary energy portfolio, energy end-use and efficiency, alternative fuels, nuclear energy, and energy production efficiency. Hence, policies should be established toward minimizing global CO2 emissions (International Energy Agency (IEA), 2014). The idea of carbon dioxide utilization (CDU) or recycling of CO2 to produce value-added chemicals was first introduced in the early 1970s (Aresta and Dibenedetto, 2007). Recently, the consumption of fossil fuels, which has led to an increase in environmental footprint, in an alternative carbon feedstock has attracted considerable attention. CO2 is perceived as a chemical raw material or a valuable source of carbon for the generation of profitable organic chemical compounds and fuels

Catalytic conversion of CO2 into methanol

131

(Aresta et al., 1992; Olah et al., 2009). A few latest findings, such as those in a techno-economic assessment on sustainable carbon capture, utilization, and storage (CCUS), have been presented in ICCDU 2015 (Karimi and Kawi, 2016). Based on these findings, researchers have been investigating a specific alternative method for CO2 consumption to demonstrate the validity of the approach to the mitigation of CO2 emissions in the context of CDU. Among various chemical transformations of CO2, hydrogenation has been found to provide excellent benefits to both the environment and the economy. CO2 hydrogenation into methanol (CH3OH) is one of the key processes that could provide a comprehensive greenhouse gas emission solution. Methanol is not only a key intermediate in the production of some chemicals, such as formaldehyde, amines, acetic acid, and esters, but also an efficient and sustainable alternative fuel owing to its cleaner emissions compared with other fossil fuels (Kothandaraman et al., 2016). Considering the advantages of CO2 hydrogenation into methanol, a new idea has been proposed called methanol economy (Olah et al., 2011). This idea provided a new method of producing renewable fuel and environmentally friendly fuel. Moreover, the recyclable CO2 provides humanity with an inexhaustible supply of carbon while reducing greenhouse gas emissions (Olah et al., 2009).

6.2 Methanol uses and applications Methanol (CH3OH) is a light, colorless, volatile liquid alcohol and is often referred to as wood alcohol. It is a methyl group connected to the hydroxyl group and is the simplest form of alcohol. Its octane number is 113, and its density is around half that of petrol (Olah, 2005). Methanol used to be generated through the thermal decomposition of wood. But since the 1920s, it has been produced catalytically using carbon monoxide and hydrogen as a feed gas, according to the process developed by BASF (Bowker, 2019). This process works well at high temperatures and pressures using several oxide catalysts, particularly a mixed material of Cr2O3
ZnO (Heilig, 1994).

6.2.1 Chemical feedstock Processed methanol is a feedstock used to manufacture chemicals, and is also used as a solvent and cosolvent, roughly around 70% of the volume. Other important substances in the petrochemical industry include

132

Carbon Dioxide Capture and Conversion

formaldehyde (HCHO), methyl tertiary-butyl ether (C5H12O), acetic acid (CH3COOH), dimethyl ether (C2H6O), propene (C3H6), methyl methacrylate (C5H8O2), and dimethyl terephthalates (C10H10O4) (Khadzhiev et al., 2016). Methanol has now become incredibly valuable in emerging economies in applications for energy and fuel, either directly or as downstream methanol products.

6.2.2 Energy source In some respects, methanol has been considered an ideal transport fuel. It can achieve considerably lower combustion chamber temperatures compared with the traditional engine fuels owing to its ability to produce high heat of vaporization as well as limited emissions of nitrogen oxides, hydrocarbons, and carbon monoxide. Nevertheless, this limitation is compensated for by increased formaldehyde emissions. Most of the vehicles fueled by methanol use M85, a combination of 85% methanol and 15% unleaded gasoline (Cifre and Badr, 2007). Moreover, as methanol is easier to transport and store than hydrogen, it can be used as a hydrogen carrier (Bozzano and Manenti, 2016).

6.2.3 Other uses Methanol has a low freezing point, and its water miscibility makes it ideal for cooling. It can be used either in a pure form or in combination with glycols and water. In the heating and cooling systems, methanol can also be used as an antifreeze. Natural gas pipelines use large amounts of methanol to inhibit the formation of low-temperature gas hydrates. Moreover, methanol has been used in the Rectisol system by Linde and Lurgi as an absorption agent in gas scrubbers. At low temperatures, it eliminates CO2 and H2S. In the purified gas, traces of methanol usually do not intervene with further processing (Dalena et al., 2018).

6.2.4 Industrial methanol synthesis Commercially, methanol is generated from natural gas via a syngas pathway. According to Eqs. (6.1) and (6.2), steam methane reforming produces a mixture of CO, CO2, and H2. Syngas combined with active CuO
ZnO
Al2O3 catalyst is then converted into methanol in the temperature range of 250°C
300°C and pressure range of 50
100 bar, as presented in Eqs. (6.3)
(6.5).

Catalytic conversion of CO2 into methanol


 3H2 ΔH298 K 206 kJ=mol
 CH4 2H2 O CO2 4H2 ΔH298 K 165 kJ=mol
 CO2 3H2 CH3 OH H2 O ΔH298 K 49:5 kJ=mol CH4

H2 O

CO

133

(6.1) (6.2) (6.3)

Typically, CO2 comprises 30% of the overall carbon in syngas (Aresta and Dibenedetto, 2007), and enhances methanol production and its energy balance. A preliminary reduction of CO does not result from the direct CO2 conversion into methanol (Saito et al., 1996). However, to accelerate the process, CO has been converted into CO2 via a water
gas shift reaction shown below:
 CO H2 O CO2 H2 ΔH298 K 41:2 kJ=mol (6.4) Eqs. (6.3) and (6.4) are exothermic. Thus, the complete synthesis reaction of methanol is the sum of the reaction given below:
 CO 2H2 CH3 OH ΔH298 K 91 kJ=mol (6.5) Under commercial operating conditions, only B20% of CO is converted based on the theoretical single-pass reaction (Bansode and Urakawa, 2014). Today, this process is quite established, and many businesses, including Lurgi, Haldor Topsoe, and Mitsubishi, provide solutions for commercial technology. However, several companies have realized that the development of the technologies for CO2 utilization is a crucial step toward a more sustainable industrial world (Bansode and Urakawa, 2014). Methanol synthesis using CO2 helps not only in mitigating the greenhouse effect but also in avoiding the expensive CO2 sequestration process (Olah, 2005). As a feedstock, CO2 is cheap, abundant, nonpoisonous, noncorrosive, and nonflammable; thus, it is safe to use. Nonetheless, an energy supply of approximately 228 103 J and six electrons are required to reduce C4 of CO2 to C2 of methanol due to the binding strength of the polar covalent bond between carbon and oxygen. Therefore, an excellent catalytic system is essential for the reduction of CO2 into methanol (Ibram, 2014).

6.2.5 Hydrogenation of CO2 into methanol Hydrogenation of CO2 into methanol using both homogeneous and heterogeneous catalysts has been tremendously investigated (Olah, 2005; Pérez-Fortes et al., 2016). However, heterogeneous catalysis is being paid

134

Carbon Dioxide Capture and Conversion

more attention than homogeneous catalysis and thus needs to be addressed in detail. The major reaction of this catalytic hydrogenation process is a combination of three reactions, namely, methanol synthesis (Eq. 6.6), reverse water
gas shift (RWGS) (Eq. 6.7), and subsequent hydrogenation of CO (Eq. 6.8) (Bansode et al., 2013). Methanol formation:
 CO2 3H2 CH3 OH H2 O ΔH298 K; 5 MPa 49:5 kJ=mol (6.6) Reverse water
gas shift reaction:
CO2 H2 CO H2 O ΔH298

K; 5 MPa

 41:2 kJ=mol

Methanol formation: CO

2H2


CH3 OH ΔH298

K; 5 MPa

91 kJ=mol



(6.7)

(6.8)

The above reactions are favorable at low temperature and thermodynamically high pressure as methanol formation is an exothermic reaction. Although Eq. (6.7) is an endothermic reaction, with decreasing entropy, its subsequent hydrogenation into methanol (Eq. 6.8) is highly exothermic. Nevertheless, CO2 has high thermal stability and is chemically inert; therefore, the intensification of reaction temperature (e.g., 240°C) helps activate CO2 and then form methanol. The RWGS reaction contributes to decreasing the formation of methanol and inducing additional hydrogen consumption (Bellotti et al., 2019). Typically, methanol is industrially synthesized from CO2-containing syngas (derived from fossil fuels) over Cu
ZnO
Al2O3 at an elevated pressure (50
100 bar) and temperature (250°C
300°C). Nonetheless, the Cu
ZnO
Al2O3 catalytic efficiency for hydrogenation from CO2 is not entirely satisfactory owing to the negative effect of large amounts of water produced from the RWGS (Goeppert et al., 2014). Thus, catalyst selectivity has a significant influence on the formation of desired products. Even so, a modified form of methanol catalyst for CO hydrogenation is still being used in CO2 hydrogenation. Numerous researchers have attempted to enhance catalytic efficiency by using multiple parameters, such as effects of the type of catalyst (e.g., surface, morphology, supports, and promoters), operating conditions, and type of reactor (Centi and Perathoner, 2009; Mikkelsen et al., 2010; Wang et al., 2008). The application of heterogeneous catalysis is still being actively investigated, especially in large-scale industries. The catalyst needs to be highly

Catalytic conversion of CO2 into methanol

135

active, selective, poison-resistant, and should have a long shelf life. An ordinary heterogeneous catalyst comprises three main constituents: active component, support, and promoter. A right formulation of these three components positively contributes to the methanol synthesis reaction performance using the optimized process parameters. A high surface area catalyst is required for facilitating reactant diffusion and adsorption. The desorption of products will be facilitated by having a catalyst with a controllable pore diameter. Consequently, porous materials with unique characteristics, such as flexibility and stability, are the right choice for catalyst support to disperse the active phase. The optimized synthesis reaction alone is not sufficient to enhance the performance of methanol production, but it should be combined with the optimization of the pre-startup process reaction. The catalyst activation and process operating conditions are some of the factors that influence the process performance for CO2 conversion and final product selectivity.

6.3 CO2 activation and its thermodynamic challenges for methanol reduction The activation of CO2 is very challenging owing to its thermodynamic stability and kinetic inertness (Alper and Orhan, 2017). CO2 has two reactive sites, namely, carbon and oxygen, and it is a nonpolar molecule. It has a strong affinity against nucleophiles and electron-donating reagents due to its carbonyl carbon deficiency; however, the oxygen atom demonstrates an opposite behavior (Li et al., 2014). Considering these features, a direct CO2 conversion into methanol requires an external power source and an effective catalyst (Rodriguez et al., 2015). Methanol synthesis using CO2-rich feed is a thermodynamically limited reaction. Increasing the reaction temperature will decrease the equilibrium conversion of CO2 (Chen et al., 2017). Furthermore, due to the exothermic nature of the CO2 hydrogenation reaction (Eq. 6.6), it will compete with the RWGS (Eq. 6.7), which is considered an endothermic reaction. Hence, even though the temperature increase accelerates CO2 activation, a high temperature will result in great selectivity for unwanted CO and H2O and decrease the conversion rate of CO2 equilibrium. Moreover, the water produced from these two reactions speeds up the sintering of the active sites in the catalyst, thus leading to catalyst deactivation and afterward reducing the successive step of methanol synthesis (Arena et al., 2009). Promoting CO2 activation, preventing by-

136

Carbon Dioxide Capture and Conversion

product formation, and operating at a temperature below 180°C are part of the essential measures to produce a high-performance methanol catalyst, which needs to be considered when designing an efficient catalytic system (Rodriguez et al., 2015).

6.4 Catalysts for hydrogenation of CO2 into methanol Catalysts of various compositions were used for the hydrogenation of CO2. Over the last few decades, extensive experimental and theoretical studies of CO2 hydrogenation have been conducted (Yang et al., 2009; Yang et al., 2010; Zhao et al., 2011). Originally, zinc chromium oxide catalysts has been used for methanol synthesis. However, a Cu-based catalyst was introduced in 1966, and it is proven that it enhances the activity and selectivity of methanol production. It has been reported that the maximum methanol yield and selectivity can be achieved with the use of metals, such as Cu, Zn, Cr, and Pd. Besides, the formation of by-products, such as hydrocarbons, can also be reduced by these metals (Lim et al., 2009). Despite the many types of metal-based catalysts that were investigated for methanol synthesis, copper-based catalysts still occupy center stage in the catalytic system.

6.4.1 Cu/ZnO-based catalysts As the 25th most abundant element in the world, copper is extensively used in catalysis for its environmental and economic advantages (Álvarez et al., 2017). Cu-based catalysts are considered among those found to be the most promising catalysts for the synthesis of methanol via hydrogenation of CO2. Some studies have undertaken detailed investigations on the role of Cu as an active catalyst. They suggested that the synthesis of methanol via hydrogenation of CO2 without copper was not feasible (Ahouari et al., 2013). Nevertheless, there are still many viewpoints on the nature and importance of copper sites. It has been suggested that the metallic copper surface area determines the Cu-based catalyst activity. However, this kind of correlation is not observed in all cases; it is only valid for samples with the same preparation history (Behrens and Schloegl, 2014). Besides, metallic copper has been reported as an active site for methanol synthesis through CO2 hydrogenation. This argument was confirmed by a kinetic model that was based on the experimental data using a Cu single crystal (Rasmussen et al., 1994). With the large fraction of oxygen-containing species in Cu0,

Catalytic conversion of CO2 into methanol

137

it has been found that the catalytic activity toward methanol synthesis does not depend on the Cu0 surface area in the presence of CO2 (Chinchen et al., 1987). The fact that cuprous ion (Cu ) sites may be involved in the synthesis of methanol confirms this discovery. The use of copper alone is not sufficient for methanol production via hydrogenation of CO2 owing to its poor selectivity to methanol, catalytic activity, and stability. Cu
ZnO has become a focus of current research owing to the ability of ZnO to enhance copper dispersion and stability due to its lattice oxygen vacancies. Furthermore, the ZnO electron pair is reportedly active for methanol synthesis (Brown et al., 2013). Initially, a dual-site and bifunctional mechanism was proposed to explain the relatively high methanol activity and selectivity on Cu
ZnO catalysts. CO2 adsorption occurs at the ZnO spot, whereas H2 is adsorbed and dissociated at the Cu site. The transition of atomic species occurs from the Cu surface to the ZnO surface, and vice versa. The absorbed carbon-containing species is further hydrogenated into methanol (Bianchi et al., 1995; Fisher and Bell, 1998). Therefore, a key element to achieving a very active catalyst for the synthesis of methanol via hydrogenation of CO2 is the formation of Cu
ZnO interphases. An enhancement in the reduction parameters (e.g., temperature, heating rate, and H2 partial pressure) was included in the critical factors during these interphases’ formation. It determines the activity of the catalyst (Tisseraud et al., 2016). Moreover, the catalytic behavior of the Cu
ZnO system is also influenced by the bare faces of ZnO interacting with Cu species (Liao et al., 2011). To improve the catalysts for this process, one should also understand the reaction mechanism on the Cu/ZnO catalysts. In this respect, catalytic hydrogenation of CO2 for methanol production using Cu/ZnO catalysts is carried out using the following two mechanisms: 1. Formate mechanism, where CO2 hydrogenation produces intermediate formates (HCOO). 2. RWGS and the mechanism for CO hydrogenation for CO2 conversion into CO, followed by methanol formation from CO hydrogenation through formyl (HCO) and formaldehyde (HCHO) intermediates (Din et al., 2019). Nevertheless, the existence of CO2 reduces the rate of methanol synthesis reaction via RWGS; thus, the chances of methanol production via the formate route are favorable (Tisseraud et al., 2016). This statement is supported by the new finding by Kattel et al. (2017). Despite that, the mechanism of methanol production is still debatable. Furthermore, there

138

Carbon Dioxide Capture and Conversion

is still no general understanding of the role of active sites and the impact of oxide support. Thus, the investigations on the metal
support interactions are well deserved. Support influences catalytic activity significantly owing to its effect on active metal dispersion and reducibility (Ha et al., 2019).

6.4.2 Catalyst supports Catalyst supports play a significant role in catalyst design. Typically, the catalyst support can disperse the active phase, demonstrating a high surface area and chemical stability while providing the active phase with thermal stability. Besides, the sintering of metal particles can be avoided (Din et al., 2019). In addition, the types of support used can also influence the basicity or acidity characteristics of the catalyst, which affect its overall performance for a specific reaction (Liu et al., 2003). The supports include amphoteric oxides, such as ZnO, ZrO2, Al2O3, MgO, Fe2O3, and SiO2 (Liu et al., 2003; Tursunov et al., 2017). As previously mentioned, Cu/ZnO supported on Al2O3 catalyst is used industrially for the methanol synthesis in syngas chemistry. To date, the catalyst has been extensively investigated for methanol synthesis using CO2 as a feed. The synergistic effects between ZnO and Cu serve as an active site for the synthesis of methanol from syngas and via CO2 hydrogenation (Tisseraud et al., 2015). ZnO plays a significant role in inducing catalyst synthesis by forming appropriate precursors that favor the dispersion and stabilization of Cu-active sites. At the same time, it speeds up CO2 adsorption, which is subsequently hydrogenated into methanol (Toyir et al., 2001). Conversely, ZnO enhances the Cu surface area, exposure, and stabilization of Cu-active centers on Al2O3 support (Behrens et al., 2012). This article will focus on alumina (Al2O3) and mesoporous silica, Santa Barbara Amorphous-15 (SBA-15) catalyst supports. 6.4.2.1 Alumina as a catalyst support Owing to its high chemical inertness, strength, and hardness, alumina is commonly used as the base material for catalytic support. Gamma-alumina (γ-Al2O3) is regarded as the most crucial alumina that can be directly applied as a catalyst and catalyst support. In particular, γ-alumina has a high surface area owing to its small particle size, which results in high surface activity for catalytic support (Itoh et al., 2015). The function of Al2O3 on Cu
ZnO
Al2O3 has been investigated by Bao (2018). The authors concluded that moderate amounts of Al2O3 are expected to increase

140

Carbon Dioxide Capture and Conversion

the H2 temperature-programmed reduction (TPR) analysis. The catalytic activity demonstrated that the CO2 conversion for CuO
ZnO
Al2O3 was 14%, whereas the MeOH selectivity was 55.3%, which was higher than those of CuO
ZnO
SiO2 (6% and 43.7%, respectively). Ha et al. (2019) conducted a theoretical study on the role of Al2O3 over Co4 cluster and reaction mechanism for methanol formation utilizing the density-functional theory (DFT). The measured data suggested that the Co4 catalyst was enhanced by Al2O3 support during the reaction owing to the Co
O bond formation. The possibility of CO adsorption increased, and when Co4 was loaded on the Al2O3 surface, the ability of C
O dissociation to generate hydrocarbons degraded. As such, methanol formation became more thermodynamically and kinetically favorable on Co4/Al2O3. Halim (2019) conducted a study on the effect of Al2O3, SBA-15, and SiC supports on Cu
ZnO-based catalyst for the hydrogenation of CO2 into methanol. The highest conversion of CO2 and selectivity of MeOH have been observed on Cu
ZnO
Al2O3 (7.67% and 42.17%, respectively), whereas Cu
ZnO
SiC presented the lowest MeOH selectivity of 0.85% with CO2 conversion of 5.44%. However, Cu
ZnO
SBA-15 exhibited the lowest CO2 conversion of 2.26% with MeOH selectivity of 4.70%, which were higher than those of Cu
ZnO
SiC. 6.4.2.2 Mesoporous silica (SBA-15) as a catalyst support In recent decades, mesoporous silica has been highly recommended as a structural base for nanotechnological applications owing to its properties, such as porosity, thermal stability, nontoxicity, and hydrothermal stability (Wagner et al., 2012; Watermann and Brieger, 2017). Moreover, the existence of an orderly structure that provides a high surface area and molecular species accessibility through the channels is the main feature in mesoporous silica. It can be used in different applications due to the probability of synthesizing various types of meso frameworks with numerous pore architecture (Kresge et al., 1992; Yanagisawa et al., 1990). Kresge et al. (1992) were the first to record ordered mesoporous silica. Since then, the morphology control, pore-size modification, formulation variation, and application of this mesoporous silica have been enhanced (Robak et al., 2010; Schüth, 2001; Wan and Zhao, 2007). The mesoporous structures are categorized into three categories: nearly spherical enclosure, cylindrical channel, and bi-continuous channel, which have been synthesized in the last few decades (Han and Zhang, 2012). SBA-type

Catalytic conversion of CO2 into methanol

141

silica is more widely studied compared with the other different ordered mesoporous silica. SBA-15 silica has interesting textural characteristics, such as large specific surface areas ( 1000 m2/g), uniform pores (4
30 nm), thickened walls of frames, small primary particles of crystallite sizes, and complimentary textured porosity. In addition, the use of SBA-15 material as support can be beneficial owing to its high surface-to-volume ratio, variable structure compositions, and high thermal stability (Rahmat et al., 2010). According to Zhao et al. (1998a,b, 2000), the standard synthesis of SBA-15 includes triblock copolymer, usually a nonionic triblock copolymer, as a structural driving agent and tetramethyl orthosilicate, tetraethyl orthosilicate, and tetrapropyl orthosilicate as sources of silica. One of the main aspects of ordered mesoporous silica synthesis is the elimination of templates. Calcination is a standard template removal process. With a calcined temperature of 500°C, final porous structure characteristics with interlattice d-spacing of 74.5
320 Å between the (100) planes, a pore volume fraction of up to 0.85, and a silica wall thickness of 31
64 Å would be produced. The effects of SBA-15 and MCM-41 on Pd catalyst activity for CO2 catalytic conversion into methanol have been studied (Koizumi et al., 2012). It was reported that the incorporation of mesoporous support led to small Pd nanoparticles. This is proven by the in-situ measurement of Pd K-edge using extended X-ray absorption fine structure (EXAFS) and hydrogen chemisorption on the small mesopore SBA-15 and MCM-41 catalysts. Tasfy et al. (2017) conducted a study on 15 wt.% Cu
ZnO supported on SBA-15 in a microactivity fixed-bed system at 250°C, 22.5 bar, with an H2
CO2 ratio of 3. In addition to its high surface area, the catalyst exhibited excellent physical and chemical characteristics of copper dispersion (DCu) and the distribution of metal. The catalytic performance demonstrated that the CO2 conversion was achieved at 14.2% with 92.1% MeOH selectivity and 51.4 g/h gcat space
time yield (STY) of MeOH. Synthesis of methanol via hydrogenation of CO2 by Pd/In2O3 supported on SBA-15 catalyst has been reported (Jiang et al., 2020). The catalyst, which has been synthesized by the two-step, citric-acid method, resulted in highly dispersed Pd and In2O3 nanoparticles supported by SBA15. The resulting catalyst exhibited good catalytic performance with 83.9% methanol selectivity, 12.6% CO2 conversion, and 1.1 10 2 mol/h/gcat STY operated at a temperature of 260°C, a pressure of 50 bar, and gas

142

Carbon Dioxide Capture and Conversion

hourly space velocity (GHSV) of 15,000 cm3/h/gcat. The catalyst was also tested under a long-run operation for 120 h, and it did not exhibit obvious catalyst deactivation, thus demonstrating to be a possible candidate for industrial use in methanol synthesis. Cu
ZnO
SBA-15 prepared via the ammonia-driving deposition
precipitation method with a Cu
Zn mass ratio of 2 has been found to effectively confine Cu nanoparticles within SBA-15 pores. Furthermore, the activity of methanol synthesis measuring below 260°C and 4 bar demonstrated optimum results with 15.6% CO conversion and 95.6% MeOH selectivity compared with the same catalyst prepared via impregnation (CO conversion: 1.2%, MeOH selectivity: 91%). The catalyst also demonstrated comparable results with the co-precipitated, highly active, and industrially implemented reference Cu
ZnO
Al2O3 with 17.5% CO conversion and 96% MeOH selectivity (García-Trenco and Martínez, 2013). CuO/ZnO/MnO (CZM) catalyst supported on different mesoporous silica (SBA-15 and MCF) for the CO2 conversion into methanol has been investigated for its morphology effect (Koh et al., 2018). The Cu crystallite size of CZM/SBA-15 was less than that of CZM/MCF after hydrogen reduction. The Cu surface area of the catalyst was inversely associated with the Cu crystallite size (CZM/SBA-15 CZM/MCF). This result was supported by the higher BET surface area of CZM/SBA15 (218 m2/g) compared with CZM/MCF (147 m2/g), which facilitates the formation of small copper crystallites by enabling higher dispersion of copper oxide. Moreover, the performance of both catalysts was measured at a reaction temperature of 180°C, a reaction pressure of 40 bar, a weight hourly space velocity of 120 L/gcat h, and H2
CO2 mole ratio of 3:1. The CO2 conversion for CZM/SBA-15 and CZM/MCF was achieved at 5.7% and 3.9%, respectively, which are well associated with the surface range of Cu, whereas the MeOH selectivity of both catalysts was relatively constant ( 99%).

6.4.3 Catalyst promoters The promoter is one of the three catalyst elements besides active metal and support. It works on the active components of the catalyst through the promotion of the desired reaction or the disruption of undesirable side products. Hence, the use of promoters can improve both the activity and the selectivity of the product (Din et al., 2019). Cu-based catalyst is structurally sensitive; thus, the addition of promoter will accelerate catalyst

Catalytic conversion of CO2 into methanol

143

reduction and help enhance the catalyst performance by changing its acidic/basic properties. It can also act as an active metal spacer. Numerous promoters for methanol synthesis based on Cu
ZnO were investigated. However, this report focuses on three types of promoters: manganese (Mn), niobium (Nb), and zirconia (Zr). The impact of the promoter on the activity of a Cu-based catalyst has been reported by Wang et al. (2010). This study aimed to identify the main difference between Cu-based catalysts and various promoters and investigate their influence on the size of copper. The result revealed that CuZnAlZr exhibited the highest methanol STY among all synthesized catalysts at 190°C
290°C. The presence of Al and Zr reduced the crystallinity of Cu, which increased the catalytic activity. When Mn was used as a promoter, the result was opposite. Tang et al. (2014) published on the influence of ZrO2 on Cu/ZnObased catalyst in another review. Catalytic efficiency in the synthesis of methanol at a reaction temperature of 170°C resulted in high methanol productivity and selectivity at 106.02 g/(kg/h) and 87.04%, respectively, compared with the one modified by Al and Ce. In the meantime, high Cu dispersion (60.71%) and high surface area of 13.92 m2/g of the uncalcined Cu/ZnO modified ZrO2 catalyst led to its high catalytic performance. The effect of the addition of Zr on the catalytic properties of Cu
Cr
Si for low-temperature methanol synthesis has been investigated by Huang et al. (2006). The specific surface area was increased by 44.84%, 87.19%, and 78.56% with increasing zirconia content from 0 to 2, 6, and 10 wt.%, respectively. TPR analyses have demonstrated that the addition of Zr favored the dispersion of the active copper part on the catalyst surface, where the oxide of copper was quickly reduced, and copper reduction was increased. For the catalytic performance, catalytic activity and methanol selectivity significantly increased, with the highest reaction turnover frequency (TOF) of 32.3% and methanol selectivity of 96.2%, with the optimum Zr addition of 6 wt.%. The effect of Zr and Mn on the efficiency of the CuO
ZnO
SBA-15 catalyst for methanol synthesis was studied by Lin et al. (2019). The incorporation of metal oxide has changed the size of the pore and the surface area of SBA-15 bare support. Furthermore, the ternary CuO
ZnO
MnO2 on SBA-15 (CZM
SBA-15) and CuO
ZnO
ZrO2 on SBA-15 (CZZ
SBA-15) exhibited high Cu dispersion (DCu), a large surface area of Cu (ACu), and a small particle size of CuO. Moreover, it is easier to reduce compared with binary CuO
ZnO on SBA-15 (CZ
SBA-15). Among the

144

Carbon Dioxide Capture and Conversion

catalysts investigated, CZZ
SBA-15 resulted in the highest methanol selectivity (25.02%), which was significantly higher than that of the CZM
SBA15 and CZ
SBA-15 catalysts. The Zr
O cluster enhanced the basic active sites, thus improving the methanol selectivity as well as the catalytic activity with its maximum oxygen vacancy concentration. In the work by Shaharun et al. (2012), 0.5 mol% of Zr-promoted Cu
ZnO
Al2O3 reduced the BET surface area from 59.87 to 35.71 m2/g. However, it increased the average pore size of the catalyst. The reducibility of the metal oxide was also influenced by the different metal support. However, the active metal was better to spread on the surface of the supporting material. Tasfy et al. (2014) investigated the effect of Mn and Pb promoters on the catalytic efficiency of Cu
ZnO
SBA-15 in a stirred high-pressure reactor for CO2 hydrogenation into methanol. The N2-adsorption study has shown that the Pb addition greatly decreases the Cu
ZnO
SBA-15 catalyst surface region. However, the surface area was slightly increased when Mn was applied. The incorporation of Mn and Pb also modified the tubular shape of the unpromoted catalyst to the granular structure. The Mn-promoted Cu
ZnO
SBA-15 catalyst resulted in 36% CO2 conversion compared with 26% for the unpromoted catalyst. The MeOH selectivity obtained using the Cu
ZnO
Mn
SBA-15 catalyst was greater than that of Cu
ZnO and Cu
ZnO
Pb catalysts supported on SBA-15. The conversion of CO2 was increased by 10%, and selectivity toward methanol improved by 20% using an Mn
Zr promoted Cu
ZnO
SBA-15 catalyst under working conditions of temperature 210°C, pressure 22.5 bar, and H2/CO2 feed ratio of 3 (Tasfy et al., 2015a). Conversely, Zabidi et al. (2016) reported the effect of the addition of Nb on the properties of Cu
ZnO
SBA-15 and its performance in methanol synthesis. The surface areas of BET and Cu increased, and the reduction and dispersion of the active sites improved. Catalytic performance with temperature 250°C, pressure 22.5 bar, and H2
CO2 feed ratio of 3 indicated that the CO2 conversion has increased to 17.1% on the Nbpromoted catalyst from 14.2% of the unpromoted catalyst. Moreover, the addition of Nb increased the yield of methanol to 143 g/h gcat compared with unpromoted Cu
ZnO
SBA-15 at 51.4 g/h gcat. As it is well known that Mn, Nb, and Zr can improve the catalytic performance of methanol synthesis, Tasfy (2016) and Halim (2019) investigated the effect of tri-promoted Mn
Nb
Zr on the catalytic performance of Cu
ZnO
SBA-15 and Cu
ZnO
Al2O3.

Catalytic conversion of CO2 into methanol

147

microstructure of the catalyst. The situation was not beneficial for methanol production (Gesmanee and Koo-Amornpattana, 2017). A method for reduction or activation of catalysts needs to be developed to achieve the optimum catalyst performance. However, given the exothermic nature of the synthesis of methanol, although the high temperature can increase the reaction rate, both high heating rate and high temperature could expedite the aggregation of surface-active sites (Liu et al., 2003). Lower activation temperatures are therefore beneficial for the dispersion of copper and increase in methanol synthesis activity (Frei et al., 2019). Gaikwad (2018) reported the effects of reduction temperature on the 30 wt.% Cu2O
ZnO catalyst for hydrogenation of CO2 into methanol at three different temperatures (250°C, 330°C, and 450°C). The catalytic performance significantly decreased when the catalyst reduced to 450°C due to Cu sintering. In contrast, Brands et al. (1996) observed that the Cu
ZnO
SiO2 catalysts demonstrated a significant increase in the rate of methanol synthesis when reduced at a high temperature (327°C
480°C). They concluded that the carbonyl activation depends on the Cu
ZnO interface. This statement was supported by Jansen et al. (2002). Their study on the use of low-energy ion scattering revealed that the applied reduction temperature strongly affected the surface composition of 63 Cu
68ZnO
SiO2. Ramirez (2018) studied the effect of calcination and reduction temperature on the Cu
ZnO catalyst for methanol production via CO2 hydrogenation. Four different calcination temperatures (300°C, 350°C, 400°C, and 600°C) were tested. The catalytic performance revealed that calcination at 600°C resulted in the lowest CO2 conversion. Meanwhile, the calcinated samples at 300°C and 350°C demonstrated a higher conversion rate of CO2 and methanol formation than the sample calcined at 600°C at reaction temperatures 240°C and 225°C, respectively. The same samples exhibited high methanol selectivity at reaction temperatures of 225°C
150°C. However, the low reaction temperature reduced CO formation. Thus, Ramirez (2018) concluded that the most suitable calcination temperature was 350°C. The impact of reduction temperature (150°C, 200°C, 250°C, 300°C, and 400°C) was evaluated for the calcined catalyst at the optimum calcination temperature, i.e., 350°C. Catalytic efficiency revealed that the optimal reduction temperature was 200° C with a maximum production of methanol obtained at the low reaction temperature, and no CO formation occurred.

148

Carbon Dioxide Capture and Conversion

6.5.2 Reaction conditions 6.5.2.1 Temperature It is commonly understood that the increase in the reaction temperature would increase the reaction rate as the molecules’ average kinetic energy increases. However, as the methanol synthesis reaction is a reversible exothermic reaction, the low reaction temperature is more beneficial. Both thermodynamics and kinetics control product distribution. Increasing the reaction temperature will decrease its equilibrium constant; hence, a high temperature is a drawback on the formation of methanol (Din et al., 2019; Liu et al., 2003). Nevertheless, the temperature to be used in the direct CO2 conversion into methanol is still under debate. The study revealed that the increase in the reaction temperature (only up to 220°C) increased the rate of methanol formation. If this temperature is further increased, the reaction rate will be slow (Fujitani and Nakamura, 2000). An et al. (2009) studied the relationship between reaction temperature (210°C
270°C) and CO2 conversion as well as methanol yield at a fixed pressure of 50 bar on the Cu
Zn
Al
Zr catalyst. The results revealed that the highest CO2 conversion was achieved at 25.8% at 250°C. However, a further increase in the temperature to 270°C decreased the CO2 conversion to 25.1% due to thermodynamic equilibrium. Furthermore, methanol yield exhibited a similar trend to CO2 conversion, where at a temperature of 210°C, methanol yield was achieved at 11.4%; nonetheless, increasing the temperature to 250°C increased methanol yield by 36%. Ahouari et al. (2013) revealed that 250°C was the optimum temperature for the maximum methanol yield using the Cu
ZnO
Al2O3 catalyst, and the methanol yield was reduced above this temperature. They found that the bulk of CO2 was transformed into CO, whereas just a proportion was hydrogenated into methanol when high temperatures were applied. They also discovered that the methanol synthesis reaction was more susceptible to reaction temperature than the RWGS reaction and that a small amount of methane formed when a reaction temperature of 350°C was applied. Similar findings were also documented by Qi et al. (2001), which increased the levels of methanol formation at 240°C. Moreover, the upward push in the reaction temperature decreased the methanol production rate and consequently increased the CO formation rate. Qi et al. (2001) also found that the control factor was the temperature of the

Catalytic conversion of CO2 into methanol

149

reaction for the transition from kinetics to thermodynamics. Likewise, increasing reaction temperature from 220°C to 300°C decreased the methanol selectivity from 37.6% to just 2.1%. Nevertheless, CO2 conversion was increased by 12.1% from 16.2%, and, hence, resulted in the selectivity of CO at 97.2% with 34.9% incremental. Moreover, from these findings, it is quite clear that the RWGS reaction enhances methanol synthesis at greater temperatures (Bill, 1998). The effect of the reaction temperature on the Cr- and Th-based catalysts supported on CuB has been investigated by Chen et al. (2002). They observed that the reaction temperature played an essential role in achieving methanol productivity, and the highest methanol yield was obtained at 275°C and 225°C, respectively. Tsubaki et al. (2001) effectively lowered the temperature in the methanol synthesis reaction to 150°C
170°C by modifying the reaction pathways using methanol as the solvent for the reaction. The STY recorded approximately 0.17 kg MeOH/L h at 170°C and 30
50 bar pressure. The purpose of lowering the temperature of the reaction is to achieve a high single-pass CO or CO2 conversion. The reaction temperature influences both the activity of the catalysts and the selectivity of the products. The reaction temperature has been defined as the main factor influencing catalyst activity and methanol selectivity (Bill, 1998). In conclusion, numerous attempts have been made to develop an active catalyst that can work at low temperatures with very favorable equilibrium. 6.5.2.2 Pressure Thermodynamically, high-pressure hydrogenation of CO2 into methanol is desirable. Methanol synthesis leads to molecular reduction, and according to the Le Chatelier theory, it is best suited for a high-pressure reaction (Din et al., 2019). Since its discovery by BASF in the 1920s, methanol synthesis has been performed at high pressure. However, the operating pressure decreased with the advent of newer catalysts. Nevertheless, with the implementation of the ICI technique in 1960, the reaction pressure was reduced to 50
100 bar with Cu
ZnO
Al2O3 as a catalyst. Graaf et al. (1988) developed a low-pressure methanol synthesizing model (15
50 bar) using CO, CO2, and H2 in the presence of the Cu
Zn
Al catalyst as a feedstock. The results indicate that both CO and CO2 can form methanol via a WGS reaction. A total of 48 kinetic-rate

150

Carbon Dioxide Capture and Conversion

models were constructed based on three key reactions and a two-site adsorption mechanism. They claimed that their model of methanol synthesis at low pressure was more accurate than all the previous models that have been reported. Jingfa et al. (1996) reported that CO2 conversion into methanol at a pressure of 20 bar resulted in high methanol selectivity at 37.9% using ultra-fine oxalate-co-precipitated Cu
ZnO
Al2O3 catalyst. At the same time, Cu
hydrophobic silica (Cu-SiO2) catalyst synthesized via the dry impregnation technique can be used for methanol synthesis at 20 bar. Kilo et al. (1997) showed that methanol synthesis with chromium oxidemodified Cu
ZrO2 catalysts at 17 bar was quite effective. The findings have demonstrated that the selectivity of methanol on Cu
ZrO2 is 70%. However, this selectivity increased to 87% with the addition of chromium oxide. Chen et al. (1999) conducted this experiment at a pressure of 10 bar using Cu
ZnO
M2O3. An et al. (2009) investigated the correlation between the pressure and CO2 conversion as well as methanol yield using fibrous Cu
Zn
Al
Zr catalyst. The results demonstrated that increasing the pressure from 20 to 50 bar increases CO2 conversion from 19% to 25.8% and methanol selectivity from 6.1% to 17.9%. They also discovered that methanol yield increased faster than the CO2 conversion, which indicated that methanol yield was more responsive than the reverse WGS reaction about the reaction pressure. This is consistent with several other studies. Meanwhile, the efficiency of Cu on Al2O3 and commercial Cu
ZnO on Al2O3 catalysts over a wide range of pressure has been evaluated by Tidona et al. (2013). They claimed that an increase in pressure from 30 to 360 bar led to an increase in methanol formation by threefold. Moreover, they found that methanol yield at temperatures below 250°C was independent of the reaction pressure. Although high pressure increases the production yield of methanol, the reaction at very high pressure is dangerous and would increase the production cost. Considering the cost and safety, the lowest possible pressure range should be maintained in methanol synthesis. Hence, new catalysts are still being developed, which allow for synthesis under low pressure (Liu et al., 2003). Table 6.2 presents the synthesis rate of methanol at various temperatures and pressures on different types of catalysts.

152

Carbon Dioxide Capture and Conversion

6.5.2.3 Space velocity The influence of space velocity on methanol synthesis reaction is another significant aspect that needs to be considered. In general, a rise in space velocity will reduce the conversion rate. However, it depends on the mechanism of the reaction. Moreover, methanol yield and methanol turnover frequency (TOF) increase with increase in GHSV ( Jingfa et al., 1996). It is important to note that when different reactant gases are used, the space velocity will have different effects (Lee et al., 1993). With increase in space velocity in CO hydrogenation, CO conversion rapidly decreased over the Cu
ZnO
Al2O3 catalyst, although methanol selectivity remained the same. However, conversion was reduced more gradually during CO2 hydrogenation, and the selectivity of methanol increased with space velocity (Liu et al., 2003). Nonetheless, as the catalytic activity reaches the thermodynamic limit, further increase in space velocity decreases catalytic activity production with a moderate to no effect. This result can be attributed to the occurrence of side reactions, which lead to ethanol and ethane formation (Gaikwad et al., 2016). Lee et al. (2000) examined the effect of space velocity on CO2
CO hydrogenation for methanol synthesis using Cu
ZnO
Al2O3 at a temperature of 250°C and pressure of 30 bar. The results revealed that a high space velocity (short contact times) produced a high rate of reaction and an increased methanol selectivity from CO2
H2. In contrast, a high space velocity resulted in a low rate of reaction and a slightly reduced selectivity of methanol from the CO
H2 feed. Gaikwad et al. (2016) investigated the effects of GHSV (650
100,000/h, equivalent to 0.37
49.85 NL/gcat/h) at a high pressure (46, 92, 184, 331, and 442 bar) and optimum temperature using commercial Cu
ZnO
Al2O3 catalyst. They observed that a very high weight
time yield (WTY) of ca. 3 gMeOH/gcat/h was achieved at a space velocity of 100,000/h and a moderate pressure of 92 bar. Moreover, it was possible to obtain excellent WTYs above 4.5 gMeOH/gcat/h at a pressure above 184 bar. Therefore, recycling unreacted CO2 and H2 as well as produced CO under high gas space velocity conditions at a relatively high pressure was also proven to be advantageous for high-yield methanol synthesis. Lachowska and Skrzypek (2004) reported the effect of GHSV on Mn-promoted Cu
Zn
Zr catalyst on the methanol production from direct CO2 conversion. The experiment was conducted at a temperature

Catalytic conversion of CO2 into methanol

155

improve CO2 conversion into methanol, a highly efficient process for CO2 conversion enhancement is still being investigated as CO2 is thermodynamically stable. Indeed, methanol production via hydrogenation of CO2 is influenced by various factors such as operating temperature and pressure, and GHSV. Furthermore, pretreatment conditions, such as calcination and reduction temperature, also contribute significantly to catalytic activity. Since direct CO2 conversion into methanol is a green technology, it should be thoroughly studied. More efforts are required on the development of relevant process technology for the highly effective smart catalyst system.

References Ahouari, H., Soualah, A., Le Valant, A., Pinard, L., Magnoux, P., Pouilloux, Y., 2013. Methanol synthesis from CO2 hydrogenation over copper-based catalysts. Reaction Kinetic Mechanism Catalysis 110 (1), 131
145. Alper, E., Orhan, O.Y., 2017. CO2 utilization: developments in conversion processes. Petroleum 3 (1), 109
126. Álvarez, A., Bansode, A., Urakawa, A., Bavykina, A., Wezendock, T., Makkee, M., et al., 2017. Challenges in the greener production of formates/formic acid, methanol, and DME by heterogeneously catalyzed CO2 hydrogenation processes. Chemical Reviews 117 (14), 9804
9838. An, X., Zuo, Y., Zhang, Q., Wang, J., 2009. Methanol synthesis from CO2 hydrogenation with a Cu/Zn/Al/Zr fibrous catalyst. Chinese Journal of Chemical Engineering 17 (1), 88
94. Arena, F., Italiano, G., Barbera, K., Bonura, G., Spadaro, L., Frusteri, F., 2009. Basic evidences for methanol-synthesis catalyst design. Catalysis Today 143 (1
2), 80
85. Aresta, M., Dibenedetto, A., 2007. Utilisation of CO2 as a chemical feedstock: opportunities and challenges. Dalton Transaction 28, 2975
2992. Aresta, M., Quaranta, E., Tommasi, I., 1992. Prospects for the utilization of carbon dioxide. Energy Conversion and Management 33 (5), 495
504. Bansode, A., Urakawa, A., 2014. Towards full one-pass conversion of carbon dioxide to methanol and methanol-derived products. Journal of Cataysis 309, 66
70. Bansode, A., Tidona, B., Von Rohr, P.R., Urakawa, A., 2013. Impact of K and Ba promoters on CO2 hydrogenation over Cu/Al2O3 catalysts at high pressure. Catalysis Science & Technology 3 (3), 767
778. Bao, H., 2018. Methanol synthesis from CO2 and H2 by reactive distillation. Master’s Thesis. School of Engineering Science, Lappeenranta University of Technology. Behrens, M., Schloegl, R., 2014. How to prepare a good Cu/ZnO Catalyst or the role of solid-state chemistry for the synthesis of nanostructured catalysts. Journal of Inorganic and General Chemistry 639 (15), 2683
2695. Behrens, M., Studt, F., Kasatkin, I., Kuhl, S., Havecker, M., Abild-Pedersen, F., et al., 2012. The active site of methanol synthesis over Cu/ZnO/Al2O3 industrial catalysts. Science (New York, N.Y.) 336 (6083), 893
897. Bellotti, D., Rivarolo, M., Magistri, L., 2019. Economic feasibility of methanol synthesis as a method for CO2 reduction and energy storage. Energy Procedia 158, 4721
4728.

156

Carbon Dioxide Capture and Conversion

Bianchi, D., Chafik, T., Khalfallah, M., Teichner, S.J., 1995. Intermediate species on zirconia supported methanol aerogel catalysts V. Adsorption of methanol. Applied Catalysis A: General 123 (1), 89
110. Bill, A., 1998. Carbon dioxide hydrogenation to methanol at low pressure and temperature. Research Dissertation, Department De Chimie, Ecole Polytechnique Federale De Lausanne. Bos, M.J., Brilman, D.W.F., 2015. A novel condensation reactor for efficient CO2 to methanol conversion for storage of renewable electric energy. Chemical Engineering Journal 278, 527
532. Bowker, M., 2019. Methanol synthesis from CO2 hydrogenation. ChemCatChem 11 (17), 4238
42462. Bozzano, G., Manenti, F., 2016. Efficient methanol synthesis: perspectives, technologies and optimization strategies. Progress in Energy and Combustion Science 56, 71
105. Brands, D.S., Poels, E.K., Krieger, T.A., Makarova, O.V., Weber, C., Veer, S., et al., 1996. The relation between reduction temperature and activity in copper catalysed ester hydrogenolysis and methanol synthesis. Catalysis Letters 36 (3
4), 175
181. Brown, N.J., Weiner, J., Hellgardt, K., Shaffer, M.S.P., Williams, C.K., 2013. Phosphinate stabilised ZnO and Cu colloidal nanocatalysts for CO2 hydrogenation to methanol. Chemical Communications 49 (94), 11074
11076. Centi, G., Perathoner, S., 2009. Opportunities and prospects in the chemical recycling of carbon dioxide to fuels. Catalysis Today 148 (3
4), 191
205. Chen, H.B., Liao, D.W., Yu, L.J., Lin, Y.J., Yi, J., Zhang, H.B., et al., 1999. Influence of trivalent metal ions on the surface structure of a copper-based catalyst for methanol synthesis. Applied Surface Science 147 (1
4), 85
93. Chen, Y.Z., Liaw, B.J., Chen, B.J., 2002. One-step synthesis of methanol from CO/H2 at low temperature over ultrafine CuB catalysts. Applied Catalysis A: General 236 (1
2), 121
128. Chen, Y., Jia, G., Hu, Y., Fan, G., Tsang, Y.H., Li, Z., et al., 2017. Two-dimensional nanomaterials for photocatalytic CO2 reduction to solar fuels. Sustainable Energy & Fuels 1 (9), 1875
1898. Chinchen, G.C., Spencer, M.S., Waugh, K.C., Whan, D.A., 1987. Promotion of methanol synthesis and the water-gas shift reactions by adsorbed oxygen on supported copper catalysts. Journal of the Chemical Society, Faraday Transaction 1: Physical Chemistry in Condensed Phases 83 (7), 2193
2212. Chinchen, G.C., Denny, P.J., Jennings, J.R., Spencer, M.S., Waugh, K.C., 1988. Synthesis of methanol. Part 1. Catalysts and kinetics. ChemInform 19 (22), 1
65. Choi, S.M., Kang, Y.J., Kim, S.W., 2018. Effect of γ-alumina nanorods on CO hydrogenation to higher alcohols over lithium-promoted CuZn-based catalysts. Applied Catalysis A: General 549, 188
196. Cifre, P.G., Badr, O., 2007. Renewable hydrogen utilisation for the production of methanol. Energy Conversion and Management 48 (2), 519
527. Dalena, F., Senatore, A., Marino, A., Gordano, A., Basile, M., Basile, A., 2018. Methanol production and applications: an overview. In: Basil, A., Dalena, F. (Eds.), Methanol: Science and Engineering. Rende, Italy, pp. 3
28. Din, I.U., Shaharun, M.S., Alotaibi, M.A., Alharthi, A.I., Naeem, A., 2019. Recent developments on heterogeneous catalytic CO2 reduction to methanol. Journal of CO2 Utilization 34, 20
33. Fisher, I.A., Bell, A.T., 1998. In situ infrared study of methanol synthesis from H2/CO over Cu/SiO2 and Cu/ZrO2/SiO2. Journal of Catalysis 178 (1), 153
173. Frei, E., Gaur, A., Lichtenberg, H., Heine, C., Friedrich, M., Greiner, M., et al., 2019. Activating a Cu/ZnO : Al catalyst
much more than reduction: Decomposition, self-doping and polymorphism. ChemCatChem 11 (6), 1587
1592.

Catalytic conversion of CO2 into methanol

157

Fujita, S.I., Moribe, S., Kanamori, Y., Kakudate, M., Takezawa, N., 2001. Preparation of a coprecipitated Cu/ZnO catalyst for the methanol synthesis from CO2
effects of the calcination and reduction conditions on the catalytic performance. Applied Catalysis A: General 207 (1
2), 121
128. Fujitani, T., Nakamura, J., 2000. The chemical modification seen in the Cu/ZnO methanol synthesis catalysts. Applied Catalysis A: General 191 (1
2), 111
129. Gaikwad, R., 2018. Carbon dioxide to methanol: stoichiometric catalytic hydrogenation under high pressure conditions. PhD Thesis, Institute of Chemical Research of Catalonia. Gaikwad, R., Bansode, A., Urakawa, A., 2016. High-pressure advantages in stoichiometric hydrogenation of carbon dioxide to methanol. Journal of Catalysis 343, 127
132. Gao, P., Xie, R., Wang, H., Zhong, L., Xia, L., Zhang, Z., et al., 2015. Cu/Zn/Al/Zr catalysts via phase-pure hydrotalcite-like compounds for methanol synthesis from carbon dioxide. Journal of CO2 Utilization 11, 41
48. García-Trenco, A., Martínez, A., 2013. A simple and efficient approach to confine Cu/ZnO methanol synthesis catalysts in the ordered mesoporous SBA-15 silica. Catalysis Today 215, 152
161. Gesmanee, S., Koo-Amornpattana, W., 2017. Catalytic hydrogenation of CO2 for methanol production in fixed-bed reactor using Cu-Zn supported on gamma-Al2O3. Energy Procedia 138, 739
744. Goeppert, A., Czaun, M., Jones, J.P., Prakash, G.K.S., Olah, G.A., 2014. Recycling of carbon dioxide to methanol and derived products
closing the loop. Chemical Society Reviews 43 (23), 7995
8048. Graaf, G.H., Stamhuis, E.J., Beenackers, A.A.C.M., 1988. Kinetics of low-pressure methanol synthesis. Chemical Engineering Science 43 (12), 3185
3195. Ha, N.N., Ha, N.T.T., Long, N.B., Cam, L.M., 2019. Conversion of carbon monoxide into methanol on alumina-supported cobalt catalyst: role of the support and reaction mechanism—a theoretical study. Catalysts 9 (1), 6. Halim, N.S.A., 2019. Synthesis, characterization and performance of copper-zinc oxide with mixed promoter catalyst for CO2 hydrogenation to methanol. Research Master Thesis, Department of Fundamental and Applied Science, Universiti Teknologi Petronas. Han, Y., Zhang, D., 2012. Ordered mesoporous silica materials with complicated structures. Current Opinion in Chemical Engineering 1 (2), 129
137. Heilig, M.L., 1994. United States Patent Office: stereoscopic television apparatus for individual use. ACM SIGGRAPH Computer Graphics 28 (2), 131
134. Huang, L., Chu, W., Long, Y., Ci, Z., Luo, S., 2006. Influence of zirconia promoter on catalytic properties of Cu-Cr-Si catalysts for methanol synthesis at high CO conversion in slurry phase. Catalysis Letters 108 (1
2), 113
118. Ibram, G., 2014. Conversion of carbon dioxide into methanol
A potential liquid fuel: fundamental challenges and opportunities (a review). Renewable and Sustainable Energy Reviews 31, 221
257. International Energy Agency (IEA), 2014. Energy technology perspectives 2014
Harness electricity’s potential: executive summary, International Energy Agency. p. 14. Itoh, T., Uchida, T., Matsubara, I., Izu, N., 2015. Preparation of γ-alumina large grain particles with large specific surface area via polyol synthesis. Ceramics International 41 (3), 3631
3638. Jansen, W.P.A., Beckers, J., Heuvel, J.C.V.D., Gon, A.W.D.V.D., Bliek, A., Brongersma, H.H., 2002. Dynamic behavior of the surface structure of Cu/ZnO/SiO2 catalysts. Journal of Catalysis 210 (1), 229
236. Jiang, X., Koizumi, N., Guo, X., Song, C., 2015. Bimetallic Pd-Cu catalysts for selective CO2 hydrogenation to methanol. Applied Catalysis B: Environmental 170
171, 173
185.

158

Carbon Dioxide Capture and Conversion

Jiang, H., Lin, J., Wu, X., Wang, W., Chen, Y., Zhang, M., 2020. Efficient hydrogenation of CO2 to methanol over Pd/In2O3/SBA-15 catalysts. Journal of CO2 Utilization 36, 33
39. Jingfa, D., Qi, S., Yulong, Z., Songying, C., Dong, W., 1996. A novel process for preparation of a Cu/ZnO/Al2O3 ultrafine catalyst for methanol synthesis from CO2 H2: comparison of various preparation methods. Applied Catalysis A: General 139 (1
2), 75
85. Kang, S.H., Bae, J.W., Oh, J.H., Jun, K.W., Song, S.L., Min, K.S., 2009. Influence of Ga addition on the methanol synthesis activity of Cu/ZnO catalyst in the presence and absence of alumina. Journal of Industrial and Engineering Chemistry 15 (5), 665
669. Karimi, I.A., Kawi, S., 2016. Technoeconomic perspectives on sustainable CO2 capture and utilization. Environmental Science and Pollution Research 23 (22), 22223
22225. Kattel, S., Ramirez, P.J., Chen, J.G., Rodriguez, J.A., Liu, P., 2017. Active sites for CO2 hydrogenation to methanol on Cu/ZnO catalysts. Science (New York, N.Y.) 355 (6331), 1296
1299. Kee, M., Jie, Y., Piao, S., Rahman, A., 2018. Carbon dioxide hydrogenation to methanol over multi-functional catalyst: effects of reactants adsorption and metal-oxide (s) interfacial area. Journal of Industrial and Engineering Chemistry 62, 156
165. Khadzhiev, S.N., Kolesnichenko, N.V., Ezhova, N.N., 2016. Slurry technology in methanol synthesis. Petroleum Chemistry 56 (2), 77
95. Kilo, M., Weigel, J., Wokaun, A., Koeppel, R.A., Stoeckli, A., Baiker, A., 1997. Effect of the addition of chromium- and manganese oxides on structural and catalytic properties of copper/zirconia catalysts for the synthesis of methanol from carbon dioxide. Journal of Molecular Catalysis A: Chemical 126 (2
3), 169
184. Koeppel, R.A., Baiker, A., Wokaun, A., 1992. Copper/zirconia catalysts for the synthesis of methanol from carbon dioxide. Influence of preparation variables on structural and catalytic properties of catalysts. Applied Catalysis A: General 84 (1), 77
102. Koh, M.K., Khavarian, M., Piao, S., Rahman, A., 2018. The morphological impact of siliceous porous carriers on copper-catalysts for selective direct CO2 hydrogenation to methanol. International Journal of Hydrogen Energy 43 (19), 9334
9342. Koizumi, N., Jiang, X., Kugai, J., Song, C., 2012. Effects of mesoporous silica supports and alkaline promoters on activity of Pd catalysts in CO2 hydrogenation for methanol synthesis. Catalysis Today 194 (1), 16
24. Kothandaraman, J., Goeppert, A., Czaun, M., Olah, G.A., Prakash, G.K.S., 2016. Conversion of CO2 from air into methanol using a polyamine and a homogeneous ruthenium catalyst. Journal American Chemical Society 138 (3), 778
781. Kowalik, P., Próchniak, W., 2011. The effect of calcination temperature on properties and activity on Cu/ZnO/Al2O3 catalysts. Annales Universitatis Mariae CurieSkłodowska, AA sectio
Chemistry 65, 79
87. Kresge, C.T., Leonowicz, M.E., Roth, W.J., Vartuli, J.C., Beck, J.S., 1992. Ordered mesoporous molecular sieves synthesized by a liquid-crystal template mechanism. Nature 359, 710
712. Lachowska, M., Skrzypek, J., 2004. Methanol synthesis from carbon dioxide and hydrogen over Mn-promoted copper/zinc/zirconia catalysts. Reaction Kinetics and Catalysis Letters 83 (2), 269
273. Lee, J.S., Lee, K.H., Lee, S.Y., Kim, Y.G., 1993. A comparative study of methanol synthesis from CO2/H2 and CO/H2 over Cu/ZnO/Al2O3 catalyst. Journal of Catalysis 144 (2), 414
424. Lee, J.S., Han, S.H., Kim, H.G., Lee, K.H., Kim, Y.G., 2000. Effects of space velocity on methanol synthesis from CO2/CO/H2 over Cu/ZnO/Al2O3 catalyst. Korean Journal of Chemical Engineering 17 (3), 332
336.

Catalytic conversion of CO2 into methanol

159

Li, Y.N., Ma, R., He, L.N., Diao, Z.F., 2014. Homogeneous hydrogenation of carbon dioxide to methanol. Catalysis Science & Technology 4 (6), 1498
1512. Liang, B., Ma, J., Su, X., Yang, C., Duan, H., Zhou, H., et al., 2019. Investigation on deactivation of Cu/ZnO/Al2O3 catalyst for CO2 hydrogenation to methanol. Industrial & Engineering Chemistry Research 58 (21), 9030
9037. Liao, F., Huang, Y., Ge, J., Zheng, W., Tedsree, K., Collier, P., et al., 2011. Morphology-dependent interactions of ZnO with Cu nanoparticles at the materials interface in selective hydrogenation of CO2 to CH3OH. Angewandte Chemie International Edition 50 (9), 2162
2165. Lim, H.W., Park, M.J., Kang, S.H., Chae, H.J., Bae, J.W., Jun, K.W., 2009. Modeling of the kinetics for methanol synthesis using Cu/ZnO/Al2O3/ZrO2 catalyst: influence of carbon dioxide during hydrogenation. Industrial & Engineering Chemistry Research 48 (23), 10448
10455. Lin, M., Na, W., Ye, H.C., Huo, H.H., Gao, W.G., 2019. Effect of additive on CuOZnO/SBA-15 catalytic performance of CO2 hydrogenation to methanol. Journal of Fuel Chemistry and Technology 47 (10), 1214
1225. Liu, X.M., Lu, G.Q., Yan, Z.F., Beltramini, J., 2003. Recent advances in catalysts for methanol synthesis via hydrogenation of CO and CO2. Industrial & Engineering Chemistry Research 42 (25), 6518
6530. Lunkenbein, T., Girgdies, F., Kandemir, T., Thomas, N., Behrens, M., Schlogl, R., et al., 2016. Bridging the Time Gap: a copper/zinc oxide/aluminum oxide catalyst for methanol synthesis studied under industrially relevant conditions and time scales. Angewandte Chemie International Edition 55 (41), 12708
12712. Ma, Y., Ge, Q., Li, W., Xu, H., 2008. Study on the sulfur tolerance of catalysts for syngas to methanol. Catalysis Communications 10 (1), 6
10. Mikkelsen, M., Jørgensen, M., Krebs, F.C., 2010. The teraton challenge. A review of fixation and transformation of carbon dioxide. Energy & Environmental Science 3 (1), 43
81. Nitta, Y., Suwata, O., Ikeda, Y., Okamoto, Y., Imanaka, T., 1994. Copper-zirconia catalysts for methanol synthesis from carbon dioxide: effect of ZnO addition to Cu-ZrO2 catalysts. Catalysis Letters 26 (3
4), 345
354. Olah, G.A., 2005. Beyond oil and gas: the methanol economy. Angewandte Chemie International Edition 44 (18), 2636
2639. Olah, G.A., Goeppert, A., Prakash, G.K.S., 2009. Chemical recycling of carbon dioxide to methanol and dimethyl ether: from greenhouse gas to renewable, environmentally carbon neutral fuels and synthetic hydrocarbons. The Journal of Organic Chemistry 74 (2), 487
498. Olah, G.A., Prakash, G.K.S., Goeppert, A., 2011. Anthropogenic chemical carbon cycle for a sustainable future. Journal of the American Chemical Society 133 (33), 12881
12898. Pérez-Fortes, M., Schöneberger, J.C., Boulamanti, A., Tzimas, E., 2016. Methanol synthesis using captured CO2 as raw material: techno-economic and environmental assessment. Applied Energy 161, 718
732. Portha, J.F., Parkhomenko, K., Kobl, K., Roger, A.C., Arab, S., Commenge, J.M., et al., 2017. Kinetics of methanol synthesis from carbon dioxide hydrogenation over copper-zinc oxide catalysts. Industrial & Engineering Chemistry Research 56 (45), 13133
13145. Qi, G.X., Zheng, X.M., Fei, J.H., Hou, Z.Y., 2001. Low-temperature methanol synthesis catalyzed over Cu/γ-Al2O3-TiO2 for CO2 hydrogenation. Catalysis Letters 72 (3
4), 191
196. Radovic, L.R., Vannice, M.A., 1987. Sulfur tolerance of methanol synthesis catalysts: modelling of catalyst deactivation. Applied Catalysis 29 (1), 1
20.

160

Carbon Dioxide Capture and Conversion

Rahmat, N., Abdullah, A.Z., Mohamed, A.R., 2010. A review: mesoporous Santa Barbara amorphous-15, types, synthesis and its applications towards biorefinery production. American Journal of Applied Sciences 7 (12), 1579
1586. Ramirez, J.D., 2018. CO2 hydrogenation to methanol at atmospheric pressure. PhD Thesis, Universidad De Castilla-La Mancha. Rasmussen, P.B., Kazuta, M., Chorkendorff, I., 1994. Synthesis of methanol from a mixture of H2 and CO2 on Cu (100). Surface Science 318 (3), 267
280. Ren, H., Xu, C.H., Zhao, H.Y., Wang, Y.X., Liu, J., Liu, J.Y., 2015. Methanol synthesis from CO2 hydrogenation over Cu/γ-Al2O3 catalysts modified by ZnO, ZrO2 and MgO. Journal of Industrial & Engineering Chemistry 28, 261
267. Robak, M.T., Herbage, M.A., Ellman, J.A., 2010. Synthesis and applications of tertbutanesulfinamide. Chemical Reviews 110 (6), 3600
3740. Rodriguez, J.A., Liu, P., Stacchiola, D.J., Senanayake, S., White, M.G., Chen, J.G., 2015. Hydrogenation of CO2 to methanol: importance of metal-oxide and metal-carbide interfaces in the activation of CO2. ACS Catalysis 5 (11), 6696
6706. Saito, Fujitani, T., Takeuchi, M., Watanabe, T., 1996. Development of copper/zinc oxide-based multicomponent catalysts for methanol synthesis from carbon dioxide and hydrogen. Applied Catalysis A: General 138, 311
318. Schüth, F., 2001. Non-siliceous mesostructured and mesoporous materials. Chemistry of Materials 13 (10), 3184
3195. Shaharun, M.S., Shaharun, S., Zabidi, N.A.M., Taha, M.F., 2012. Effect of zirconia on the physicochemical properties of Cu/ZnO/Al2O3 catalyst. AIP Conference Proceedings 1482 (1), 117
121. Słoczy´nski, J., Grabowski, R., Kozlowska, A., Olszewski, P., Stoch, J., Skrzypek, J., et al., 2004. Catalytic activity of the M/(3ZnO  ZrO2) system (M Cu, Ag, Au) in the hydrogenation of CO2 to methanol. Applied Catalysis A: General 278 (1), 11
23. Song, J., Liu, S., Yang, C., Wang, G., Tian, H., Zhao, Z., et al., 2020. The role of Al doping in Pd/ZnO catalyst for CO2 hydrogenation to methanol. Applied Catalysis B: Environmental 263, 118367. Sun, J.T., Metcalfe, I.S., Sahibzada, M., 1999. Deactivation of Cu/ZnO/Al2O3 methanol synthesis catalyst by sintering. Industrial & Engineering Chemistry Research 38 (10), 3868
3872. Tagawa, T., Plezier, G., Amenomiya, Y., 1985. Methanol synthesis from CO2 H2. I. characterization of catalysts by TPD. Applied Catalysis 18, 285
293. Tang, X.B., Noritatsu, T., Xie, H.J., Han, Y.Z., Tan, Y.S., 2014. Effect of modifiers on the performance of Cu-ZnO-based catalysts for low-temperature methanol synthesis. Journal of Fuel Chemistry and Technology 42 (6), 704
709. Tasfy, S.F.H., 2016. Development and performance analysis of Cu-ZnO/SBA-15 catalysts for hydrogenation of carbon dioxide to methanol. PhD Thesis, Chemical Engineering Department, Universiti Teknologi Petronas. Tasfy, S.F.H., Zabidi, N.A.M., Shaharun, M.S., Subbarao, D., 2014. Effect of Mn and Pb promoters on the performance of Cu/ZnO-catalyst in CO2 hydrogenation to methanol. Applied Mechanics and Materials 625, 289
292. Tasfy, S.F.H., Zabidi, N.A.M., Shaharun, M.S., Subbarao, D., 2015a. The influence of Mn, Zr and Pb promoters on the performance of Cu/ZnO/SBA-15 catalyst for hydrogenation of CO2 to methanol. Defect and Diffusion Forum 365, 178
182. Tasfy, S.F.H., Zabidi, N.A.M., Shaharun, M.S., Subbarao, D., 2015b. The role of support morphology on the performance of Cu/ZnO-catalyst for hydrogenation of CO2 to methanol. AIP Conference Proceedings 1669, 02000.

Catalytic conversion of CO2 into methanol

161

Tasfy, S.F.H., Zabidi, N.A.M., Shaharun, M.S., Subbarao, D., Elbagir, A., 2017. Carbon dioxide hydrogenation to methanol over Cu/ZnO-SBA-15 catalyst: effect of metal loading. Defect and Diffusion Forum 380, 151
160. Tidona, B., Koppold, C., Bansode, A., Urakawa, A., Rohr, P.R.V., 2013. CO2 hydrogenation to methanol at pressures up to 950 bar. The Journal of Supercritical Fluids 78, 70
77. Tisseraud, C., Comminges, C., Belin, T., Ahouari, H., Soualah, A., Pouilloux, Y., et al., 2015. The Cu-ZnO synergy in methanol synthesis from CO2, part 2: origin of the methanol and CO selectivities explained by experimental studies and a sphere contact quantification model in randomly packed binary mixtures on Cu-ZnO coprecipitate catalysts. Journal of Catalysis 330, 533
544. Tisseraud, C., Comminges, C., Pronier, S., Pouilloux, Y., Le Valant, A., 2016. The Cu
ZnO synergy in methanol synthesis Part 3: impact of the composition of a selective Cu@ZnO x core
shell catalyst on methanol rate explained by experimental studies and a concentric spheres model. Journal of Catalysis 343 (40), 106
114. Toyir, J., De la Piscina, P.R., Fierro, J.L.G., Homs, N., 2001. Catalytic performance for CO2 conversion to methanol of gallium-promoted copper-based catalysts: influence of metallic precursors. Applied Catalysis B: Environmental 34 (4), 255
266. Tsubaki, N., Ito, M., Fujimoto, K., 2001. A new method of low-temperature methanol synthesis. Journal of Catalysis 197 (1), 224
227. Tursunov, O., Kustov, L., Tilyabaev, Z., 2017. Methanol synthesis from the catalytic hydrogenation of CO2 over CuO
ZnO supported on aluminum and silicon oxides. Journal of the Taiwan Institute of Chemical Engineers 78, 416
422. Twigg, M.V., Spencer, M.S., 2001. Deactivation of supported copper metal catalysts for hydrogenation reactions. Applied Catalysis A: General 212 (1
2), 161
174. Wagner, T., Haffer, S., Weinberger, C., Klaus, D., Tiemann, M., 2012. Mesoporous materials as gas sensors. Chemical Society Reviews 42, 4036
4053. Wan, Y., Zhao, D., 2007. On the controllable soft-templating approach to mesoporous silicates. Chemical Reviews 107 (7), 2821
2860. Wang, X.G., Zhang, D.M., Luo, T., Deng, X.J., Lin, G.B., 2008. Fixation and conversion of CO2 using ionic liquids. Modern Chemical Industry 28 (2), 18
23. Wang, G., Zuo, Y., Han, M., Wang, J., 2010. Copper crystallite size and methanol synthesis catalytic property of Cu-based catalysts promoted by Al, Zr and Mn. Reaction Kinetics, Mechanisms and Catalysis 101, 443
454. Watermann, A., Brieger, J., 2017. Mesoporous silica nanoparticles as drug delivery vehicles in cancer. Nanomaterials 7 (7), 189. Wu, J., Luo, S., Toyir, J., Saito, M., Takeuchi, M., Watanabe, T., 1998. Optimization of preparation conditions and improvement of stability of Cu/ZnO-based multicomponent catalysts for methanol synthesis from CO2 and H2. Catalysis Today 45 (1
4), 215
220. Xian-ji, G.U.O., Li-min, L.I., Shu-min, L.I.U., Gai-ling, B.A.O., Wen-hua, H.O.U., 2007. Preparation of CuO/ZnO/Al2O3 catalysts for methanol synthesis using parallelslurry-mixing method. Journal of Fuel Chemistry and Technology 35 (3), 329
333. Yanagisawa, T., Shimizu, T., Kuroda, K., Kato, C., 1990. The preparation of alkyltrimethyllammonium-kanemite complexes and their conversion to microporous materials. Bulletin of the Chemical Society of Japan 63 (4), 988
992. Yang, Y., Mims, C.A., Disselkamp, R.S., Peden, C.H.F., Campbell, C.T., 2009. Simultaneous MS-IR studies of surface formate reactivity under methanol synthesis conditions on Cu/SiO2. Topics in Catalysis 52 (10), 1440
1447. Yang, Y., Mims, C.A., Disselkamp, R.S., Kwak, J.H., Peden, C.H.F., Campbell, C.T., 2010. (Non)formation of methanol by direct hydrogenation of formate on copper catalysts. The Journal of Physical Chemistry C 114 (40), 17205
17211.

162

Carbon Dioxide Capture and Conversion

Zabidi, N.A.M., Tasfy, S.F.H., Shaharun, M.S., 2016. Effects of Nb promoter on the properties of Cu/ZnO/SBA-15 catalyst and performance in methanol production. Key Engineering Materials 708, 94
97. Zhai, X., Shamoto, J., Xie, H., Tan, Y., Han, Y., Tsubaki, N., 2008. Study on the deactivation phenomena of Cu-based catalyst for methanol synthesis in slurry phase. Fuel 87 (4
5), 430
434. Zhao, D., Feng, J., Huo, Q., Melosh, N., Fredrickson, G.H., Chmelka, B.F., et al., 1998a. Triblock copolymer syntheses of mesoporous silica with periodic 50 to 300 angstrom pores. Science (New York, N.Y.) 279 (5350), 548
552. Zhao, D., Huo, Q., Feng, J., Chmelka, B.F., Stucky, G.D., 1998b. Nonionic triblock and star diblock copolymer and oligomeric surfactant syntheses of highly ordered, hydrothermally stable, mesoporous silica structures. Journal of the American Chemical Society 120 (24), 6024
6036. Zhao, D., Sun, J., Li, Q., Stucky, G.D., 2000. Morphological control of highly ordered mesoporous silica SBA-15. Chemistry of Materials 12 (2), 275
279. Zhao, Y.F., Yang, Y., Mims, C., Peden, C.H.F., Li, J., Mei, D., 2011. Insight into methanol synthesis from CO2 hydrogenation on Cu (1 1 1): complex reaction network and the effects of H2O. Journal of Catalysis 281 (2), 199
211. Zhou, R.X., Yu, T.M., Jiang, X.Y., Chen, F., Zheng, X.M., 1999. Temperatureprogrammed reduction and temperature-programmed desorption studies of CuO/ ZrO2 catalysts. Applied Surface Science 148 (3
4), 263
270.

CHAPTER 7

Application of calcium looping (CaL) technology for CO2 capture Nader Mahinpey, Seyed Mojtaba Hashemi, S. Toufigh Bararpour and Davood Karami Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, Canada

7.1 Introduction Different technologies have been proposed to reduce CO2 emission from point sources (e.g., fossil fuel power plants, cement, iron, and steel industries), including post-combustion, oxy-fuel combustion, chemical looping combustion (CLC), and pre-combustion. Currently, low-temperature carbon capture (with amine-based sorbents, physical/chemical adsorbents, etc.) and high-temperature carbon capture (with Li2ZrO3, CaO, etc.) are being extensively studied as the main CO2 capturing techniques in postcombustion technology (Kunze and Spliethoff, 2012). Post-combustion amine scrubbing is the most developed method to mitigate CO2, employing an amine-based solvent (such as MEA) as the working fluid. Oxy-fuel combustion is another close-to-market technology, producing an almost pure CO2 in the output, ready for utilization or sequestration. CLC is usually categorized under oxy-fuel combustion processes in which specific materials called oxygen carriers are employed to transfer oxygen from the air to the fuel reactor for the complete combustion of the fuel. Pre-combustion is a promising technique applicable for the gasification of fuel to produce syngas or hydrogen. Unfortunately, these technologies suffer from several drawbacks and limitations, and in terms of economic viability and market feasibility, need significant improvements. In amine scrubbing, the degradation of the solvents and corrosive nature of amine necessitate continuous solvent replacement and system maintenance. In oxy-fuel, providing an O2 stream by an air separation unit (ASU) increases the energy consumption and cost of the process considerably. Precombustion cannot be retrofitted to existing plants, and significant changes and reconstruction are required in the CO2 capturing facilities. CLC is an innovative and effective technique for removing CO2; however, it has Carbon Dioxide Capture and Conversion DOI: https://doi.org/10.1016/B978-0-323-85585-3.00004-3

© 2022 Elsevier B.V. All rights reserved.

163

164

Carbon Dioxide Capture and Conversion

some drawbacks, including oxygen carrier attrition and agglomeration. Therefore, researchers are still working to improve the existing technologies or develop alternative, more viable, and easily applicable carbon capture techniques to resolve the existing issues. It is worth noting that, generally, carbon capture and sequestration (CCS) technologies consist of three key steps including capture, transport, and storage, among which capturing CO2 is the costliest step (60%
70% of the total CCS cost), requiring deep studies and evaluations to make the process economically feasible. CaL has attracted attention in the last 15 years as a promising CO2 adsorption technique, utilizing widely available and low-cost CaO-based solid sorbents (Boot-Handford et al., 2014; Shimizu et al., 1999). CaL was introduced by Shimizu et al. in 1999, and since then, significant improvements and modifications have been made in the process and working materials (Shimizu et al., 1999). The cost of capturing CO2 by using CaO is considered low (about US $24/ton of captured CO2) compared to other approaches such as amine scrubbing (US $52/ton) (Chen et al., 2020). However, the theoretical adsorption capacity of CaO (0.786 g CO2/g CaO) is in the same range as MEA (0.720 g CO2/g MEA) (Chen et al., 2020; Huertas et al., 2015). One of the most important advantages of CaL is the possibility to directly employ flue gases at their original high temperature, which reduces the energy penalty associated with CO2 capture (Perejón et al., 2016). In this chapter, a review is conducted on CaO-based sorbents employed for the CaL process. The review consists of a broad overview of CaO sorbents and a detailed description of the technical approaches to enhance the overall performance of the system. A suitable sorbent should possess several properties to be applicable for the CaL process, including high and fast CO2 uptake capacity, stability and durability over multicycle operations, high attrition resistance and mechanical strength, acceptable CO2 capture kinetics, availability, economic feasibility, as well as easy and fast regeneration capability. In the following sections, efforts towards development of suitable sorbents for the CaL process are reivewed, and challenges yet to be resolved are highlighted.

7.2 Calcium looping process CaL is employed either in post- or pre-combustion processes. Fig. 7.1 demonstrates a schematic of CaL application in post-combustion. The system typically consists of two interconnected fluidized beds for carbonation and calcination. After the combustion of fuel in the combustion chamber,

Application of calcium looping (CaL) technology for CO2 capture

Fuel

Air

Air

Combustor

Air Separaon Unit

O2

Flue gas

Carbonator

165

CaCO3

N2

Fuel

Calciner

CaO CO2

Clean flue gas

Figure 7.1 Cyclic CO2 capture in calcium looping process.


the flue gas goes to the carbonator to remove the associated CO2. The carbonation reaction (Eq. 7.1) takes place at a temperature between 600°C and 700°C, yielding CaCO3, which is then calcined in the calciner (Eq. 7.2) at a temperature between 900°C and 950°C (Erans et al., 2016). The outlet of the carbonator is clean flue gas with minimal CO2 concentration. Calcination is an endothermic reaction, which proceeds to completion rapidly under different ranges of operating conditions (Silaban and Harrison, 1995).   kj CaOðsÞ CO2ðgÞ CaCO3ðsÞ ΔH 178 (7.1) mol  CaCO3ðsÞ

CaOðsÞ

CO2ðgÞ

ΔH

178

 kj mol

(7.2)

Using pure N2 for calcination results in the decomposition of CaCO3 starting at a temperature of about 750°C (Liu and Wu, 2019). By increasing the calcination temperature, the CaCO3 decomposition occurs faster. At a temperature of 850°C, the decomposition completes in 10 min in the presence of pure nitrogen (Ma et al., 2017). However, almost pure CO2 is required in the outlet suitable for sequestration or utilization, and using N2 in the calciner dilutes the outlet CO2 stream. Hence, the heat of calcination is supplied by burning fuel with pure O2 instead of using N2 (Shimizu et al., 1999). To supply pure O2, an ASU is needed (like oxy-fuel

166

Carbon Dioxide Capture and Conversion

combustion), which increases the energy consumption and cost of the system. However, it should be noted that the size and energy consumption of ASU needed for a CaL cycle is one-third of the ASU needed for a typical oxy-fuel process (MacDowell et al., 2010). In addition, the energy penalty of ASU is partially recovered by the hot streams of CO2 and CaO, and heat produced by the exothermic carbonation reaction (MacDowell et al., 2010). The released heat from these streams can be employed for additional steam generation. In the carbonator, the reaction between CaO and CO2 proceeds fast initially, and when the carbonation gets close to the completion, the reaction rate decreases significantly (Arias et al., 2011a,b). Fig. 7.2 displays different stages during the carbonation of a CaO-based sorbent. In the beginning, the carbonation is controlled by chemical reaction kinetic, and when the thickness of the CaCO3 layer reaches the critical level (about 50 nm), the rate is limited by the diffusion of the reactants through the product layer (Alvarez and Abanades, 2005). After the critical level, CO2 can react with CaO only after diffusing through the layer and reaching the CaO surface, which reduces the overall rate of the reaction. The CaL process is operated under atmospheric pressure (Shimizu et al., 1999). At a specific temperature, if CO2 is at a higher partial pressure than the equilibrium partial pressure, carbonation occurs. On the other hand, if CO2 partial pressure is lower than the equilibrium pressure, the calcination reaction proceeds (Dean et al., 2011). The equilibrium partial pressure of

3

3

2 Conversion

2

1 CaCO3

CO2 CaO

1

Time

Figure 7.2 Chemical reaction and diffusion stages during sorbent conversion in the carbonation step.


Application of calcium looping (CaL) technology for CO2 capture

167

CO2 is calculated by Eq. (7.3). Assume a very high CO2 concentration in the calciner (CO2 partial pressure of B1 bar), then a temperature of above 900°C is required to calcine the sorbent. In practice, the concentration of CO2 in the calciner is between 70% and 90% vol., which necessitates utilizing a calcination temperature of up to 950°C (Charitos et al., 2011; Martínez et al., 2013). The most viable method to provide this temperature is burning fuel with pure O2 in calciner (Arias et al., 2013). LogPCO2 ; eq

7:079

8308 T

(7.3)

The schematic process shown in Fig. 7.1 indicates the application of CaL in post-combustion processes, such as in power stations or cement industrial processes. It is worth noting that the exhausted CaO in the CaL process can be used as a feedstock in the cement industry to replace the fresh limestone (MacDowell et al., 2010). The most mature application of CaL is in post-combustion processes and is rapidly evolving for use in pilot-scale units. However, CaL can also be employed in precombustion for capturing CO2 from the steam or oxy-gasification processes and enhancing clean hydrogen fuel production. Compared to post-combustion, pre-combustion CO2 capture separates CO2 from process gas streams prior to burning. In this process, CaL is combined with a water
gas shift (WGS) reaction. After producing syngas (CO H2) in the gasification, more H2 is produced by the reaction between CO and steam through the WGS reaction. The produced CO2 in WGS can be captured by a CaO-based sorbent in a CaL process to shift the reaction forward and enhance H2 production according to Le Chatelier’s principle (Ramkumar and Fan, 2010). Fig. 7.3 displays a simple schematic of a gasification reaction coupled with a CaL process (Dean et al., 2011). A novel gasification technique was invented for sorption-enhanced H2 production from coal, known as HyPr-RING (Mostafavi et al., 2016). The HyPrRING technique consists of combining the steam gasification of coal, the WGS reaction, and CO2 capture into a single step in one reactor (Mostafavi et al., 2016).

7.3 Reactivity decay of CaO-based sorbents An important issue in working with CaO-based sorbents is the decay of the sorbent’s reactivity over multiple carbonation and calcination cycles. It has been observed that the multicycle conversion of CaO follows

168

Carbon Dioxide Capture and Conversion

Fuel

H 2O

Air

Gasifier

Syngas

Air Separaon Unit

O2

O2

Steam CaCO3

Carbonator/ Reformer

N2

Fuel

Calciner

CaO

H2

CO2

Figure 7.3 Pre-combustion combined with CaL process. CaL,

.




the semiempirical Eq. (7.4) (Grasa and Abanades, 2006; Valverde et al., 2014a,b). 2 3 XN X1

Xr X1

6 4

kðN

1Þ

1  1

Xr X1

7  1 5; ðN

1; 2; . . .Þ

(7.4)

Where N is the number of cycles, X1 is the conversion in the initial cycle, XN is the conversion in cycle N, Xr is the residual conversion after many cycles when the conversion stabilizes around a specific value, and k is the deactivation constant. The residual conversion of natural CaO is usually between 0.07 and 0.08, which is considered low (Grasa and Abanades, 2006; Wang et al., 2010). Therefore, various techniques have been proposed to enhance the mechanical strength, stability, and reactivity of CaObased materials, which are explained in detail in the following sections. Different factors can induce reactivity decay in CaO-based sorbents, including sintering of CaO particles (Dean et al., 2011), the competing reactions between CaO and impurities existing in the flue gas (Lyngfelt and Leckner, 1989), and loss of the bed’s active materials because of attrition (Lu et al., 2008a,b).

7.3.1 Sintering Sintering means changes in pore shape, grain growth, and pore shrinkage of the particles under cyclic reactions, resulting in reduced surface area

Application of calcium looping (CaL) technology for CO2 capture

169

and reactivity. It has been observed that sintering significantly accelerates at temperatures above 900°C (Blamey et al., 2010a,b). Sintering increases by increasing the partial pressure of steam and CO2 as well (Borgwardt, 1989). Thus, there is a higher chance of sintering in the calcination step as the temperature and CO2 concentration are high (Sun et al., 2007a,b). In several studies, it was observed that the pore size distribution of the particles became bimodal after the multicycle reactions, including two ranges of pore sizes. The small pores were created because of the release of CO2 molecules from the sorbent during calcination (Alvarez and Abanades, 2005; Sun et al., 2007a,b). Large pores in the particles were attributed to the sintering, in which the small pores converted to larger pores by the minimization of surface energy (Erans et al., 2016). It was found that during carbonation, the small pores plug and do not reopen in the calcination step (Fennell et al., 2007). The reason for this occurrence can be observed by comparing the physical properties of CaO and CaCO3 in Table 7.1. As seen in Table 7.1, a significant volumetric change occurs in each carbonation/ calcination cycle. The molar density of the calcined sorbents (CaO) is 16.9 cm3/mol, whereas the molar density of the carbonated sorbents (CaCO3) is 36.9 cm3/mol. This significant textural variation in each cycle collapses or reshapes the pores (Chen et al., 2020). Fig. 7.4 demonstrates a schematic for structural changes in CaO particles over cyclic carbonation/ calcination, caused by sintering. First, CaCO3 is calcined to form a porous CaO. CaO is carbonated in the next step. However, the carbonation is not complete because some pores are blocked. Some of these pores do not reopen in the next calcination, leading to reduced pore volume and surface area. These steps are repeated until a considerably less reactive sorbent is obtained in the end.

Table 7.1 Physical properties of calcium compounds. Compound

Molar mass (g/mol)

Mass density (g/cm3)

Molar density (cm3/mol)

CaO CaCO3

56 100

3.3 2.7

16.9 36.9

Source: Reproduced with permission from Chen, J., Duan, L., Sun, Z., 2020. Review on the development of sorbents for calcium looping. Energy & Fuels 34 (7), 7806
7836.

170

Carbon Dioxide Capture and Conversion

Figure 7.4 A schematic for structural changes in CaO over repeated carbonation/calcination cycles.


7.3.2 Reaction with impurities Reaction with impurities can reduce CaO’s reactivity toward CO2, especially if SO2 is present in the flue gas. CaO has a strong affinity toward SO2 under the operating conditions used for the CaL process (Ryu et al., 2006; Sun et al., 2007a,b). CaO can directly react with SO2 according to Eq. (7.5) and form CaSO4. In addition, SO2 indirectly reacts with carbonated calcium (Eq. 7.6) and yields CaSO4 (Dean et al., 2011). Sulfated sorbents (CaSO4) require very high temperatures to regenerate, which does not occur under the CaL process conditions. CaSO4 also causes pore blockage because the molar volume of CaSO4 is high.  1 kj CaOðsÞ SO2ðgÞ ΔH 502 O2ðgÞ CaSO4ðsÞ (7.5) 2 mol

CaCO3ðsÞ

SO2ðgÞ

1 O2ðgÞ 2

CaSO4ðsÞ

CO2ðgÞ

 ΔH

kj 502 mol (7.6)

7.3.3 Attrition Attrition is another important factor, declining the reactivity of CaObased sorbents, which can occur in different stages and with different mechanisms over CaL cycles. During calcination, CO2 is released from

Application of calcium looping (CaL) technology for CO2 capture

171

the particles, inducing overpressure and primary fragmentation in the particles. In addition, the thermal stress during carbonation/calcination cycles intensifies the fragmentation. Attrition can also occur because of the mechanical stress caused by striking particles to each other or the reactor’s wall. In addition, abrasion produces fine particles and reduces the overall reactivity of the system. In many works, it has been observed that the attrition rate is severe in the first couple of cycles and then reduces and stabilizes at a specific value (Coppola et al., 2012a,b). As a consequence of particles’ deactivation and attrition, in each cycle, a great portion of active material (CaO) is lost, which is required to be replaced with a make-up flow of fresh CaO in the calciner. The periodic addition of fresh particles increases the heat demand in the calciner (Kunze and Spliethoff, 2012; Lisbona et al., 2013). For post-combustion applications, the optimum CO2-carrying capacity to minimize the heat demand in calciner is about 0.2 (molar conversion of Ca) (Rodriguez et al., 2008). To provide this amount in conventional CaL processes, a CaO make-up of 50
100 t/h is required in a coal power plant with 1000 MWt capacity, which makes the process costly (Abanades, 2002). CaO is considered a cheap and abundant sorbent, and in the first look, the replacement of elucidated sorbent with fresh ones does not seem a big issue. However, it should be noted that the addition of new sorbents increases the fuel and oxygen consumption in the calciner, imposing a significant energy penalty on the whole system. One of the effective approaches to reduce the quantity of replaced sorbents is the recarbonation of the partially carbonated sorbents by using recovered CO2 obtained from the calciner. This modification in the CaL process proposes a new system with improved capture efficiency and reduced heat demand and cost (Diego et al., 2013; Grasa et al., 2014). Fig. 7.5 shows a schematic of a CaL process used for post-combustion CO2 capture modified by an intermediate carbonation step. Experiments showed that the residual conversion of natural CaO increased from about 0.07 in the conventional CaL process to about 0.16 in the modified system, including the recarbonator (Arias et al., 2012; Valverde et al., 2014a,b). In each cycle, recarbonation enhances CaO conversion and compensates for the reactivity decay over cyclic operations. In the following paragraph, it is explained why recarbonation improves the efficiency of the system. In various studies, it was found that the carbonation of CaO over an extended carbonation time (up to 30 min) reduced the reaction decay

172

Carbon Dioxide Capture and Conversion

Storage

CO2 Flue gas

Parally carbonated CaO

Carbonator 600 °C – 700 °C

Recarbonator ~ 800 °C

Recarbonated CaO

Calciner >900 °C

CaO Clean flue gas

O2, fuel

Figure 7.5 Schematic of CaL process including a recarbonation step. CaL, .





(Lysikov et al., 2007; Sun et al., 2008a,b). It was shown that increasing the CO2 partial pressure has a positive impact on the reactivity of CaObased sorbents and delays the reactivity decay (Dennis and Pacciani, 2009). These changes (increasing residence time and CO2 partial pressure) are effective in improving the capturing efficiency when the sorbent reaches the slow kinetic regime (diffusion-limited regime) (Arias et al., 2010, 2011a,b). This is what happens in the recarbonation step. In the recarbonator, the CO2 partial pressure is high (about 1 atm), and the residence time is extended; thus, the capturing efficiency of the sorbent improves. However, in the carbonator, the residence time is low ( 5 min) and the partial pressure of CO2 is below 0.15 atm (Charitos et al., 2011; Rodriguez et al., 2011).

7.4 Natural and synthetic CaO-based sorbents For CaL technology, thermodynamic calculations describe that calcium oxide is the optimum sorbent that possesses better thermodynamic and chemical characteristics (Chen et al., 2020), along with regeneration capability compared to other metal oxides. Furthermore, CaO is widely employed because of its low price and abundance, environmental

Application of calcium looping (CaL) technology for CO2 capture

173

harmlessness, nontoxicity, flexibility for use in fluidized bed reactors (FBRs), fast carbonation and calcination kinetics, and possibility for utilizing in the cement industry. A significant portion of this chapter is dedicated to the preparation and stabilization of CaO for the CaL process. CaO-based sorbents are classified into two groups—natural sorbents and synthetic sorbents.

7.4.1 Natural sorbents Naturally occurring CO2 sorbents such as limestone are great candidates for the CaL process owing to their low cost and wide availability. One of the main impediments of the widespread use of natural sorbents is the loss of the CO2 capture capacity over cyclic operations (Hughes et al., 2004; Salvador et al., 2003). This challenge needs to be addressed before the process is applied in commercial scales. Therefore, many researchers have aimed to either improve the stability and uptake capacity of naturally occurring sorbents or introduce new sorbents that possess superior stability and uptake capacity. In this section, the modification techniques for the improvement of naturally occurring sorbents are reviewed, and the next section will focus on the progress made in synthetic CaO-based sorbents. Researchers have investigated several natural sorbents, including limestone (Chen et al., 2010, 2011), dolomite (Li et al., 2008a,b; Sun et al., 2018), lime mud (Ma et al., 2016; Sun et al., 2013; Zhang et al., 2018), eggshells (He et al., 2017; Shan et al., 2016), and seashells (Huang et al., 2018; Wang et al., 2014). However, all these sorbents exhibit a significant drop in the CO2 uptake over cycles. The loss in the uptake was associated with the solid-state sintering of the sorbents at elevated calcination temperatures, which resulted in the reduced surface area and porosity (Blamey et al., 2010a,b; Borgwardt, 1989). Moreover, the formation of calcium sulfate when treating flue gases containing sulfur oxides was the second reason for the loss of active sorbents because of the irreversibility of the sulfation reaction (Anthony and Granatstein, 2001; Diego et al., 2013). Another factor contributing to the drop in the CO2 uptake was the loss of fine materials in FBRs due to attrition and elutriation (Cook et al., 1996; Ma et al., 2020). Considering these challenges, researchers have employed different strategies to improve sorbent performance in terms of resistance to sintering and attrition. An ideal sorbent must maintain a high uptake capacity during cyclic operation, while exhibiting high mechanical

174

Carbon Dioxide Capture and Conversion

resistance. Some of the sorbent activation/reactivation strategies are chemical pretreatment, doping, and incorporation of sintering-resistant supports. Preventing sorbent sulfation is not an easy task because the majority of reactive sorbents toward CO2 also have a high affinity to SO2 (Anthony and Granatstein, 2001). The formation of sulfates results in the loss of active material because the sulfation process is irreversible at common calcination temperatures. Therefore, the use of fuels with low sulfur content or desulfurization of the flue gas has been suggested to prevent sulfate formation in the carbonator. 7.4.1.1 Doping of naturally occurring sorbents Researchers have investigated the use of dopants to decrease the rate of loss of CO2 uptake capacity in the cyclic operation of CaO-based sorbents. The main doping techniques that have been investigated so far are wet impregnation (WI) and dry mixing (DM) methods. The WI method consists of preparing a solution of known molarity of the dopant and then pouring the solution onto the sorbent. The solution is then mixed, sealed, and remained for a specific period, after which the solution is decanted and the solid residue is dried. In the DM method, limestone is directly mixed with the undissolved salts. DM is much less energy-intensive compared to WI, as it does not include a drying step. DM also allows calculating the dopant content by a mass balance. Salvador et al. (2003) doped Havelock limestone with NaCl and Na2CO3 using WI. Solutions of the salts (20 wt.%) were prepared and poured over limestone samples (particle size range of 650
1675 μm). The mixing of the solution continued for 20 min and then the solution was dried overnight at 120°C. Prior to the carbonation experiments, samples were calcined at 850°C under an N2 environment. Samples were then tested in a thermogravimetric analyzer (TGA) and a fluidized bed combustor (FBC). Doped sorbents did not present an improved CO2 capture performance in the FBC. However, the samples doped with NaCl showed significant improvements in TGA, improving the CO2 capture capacity to about 40% in 13 carbonation/calcination cycles. Fennell et al. (2007) also doped Purbeck limestone (500
710 μ) with Na2CO3 and NaCl solutions of known molarity (0.5 M NaCl; 0.002, 0.01, and 0.5 M Na2CO3). Doped samples were tested in a lab-scale FBR (internal diameter 29.5 mm and length 460 mm). The results indicated that particles doped with small quantities of the salts exhibited slight

Application of calcium looping (CaL) technology for CO2 capture

175

improvement over the long-term CO2 capture test. However, a larger quantity of dopants resulted in a reduced CO2 capture capacity. González et al. (2011) used a WI technique to dope Imeco and Havelock limestones from Spain and Canada, respectively, with KCl and K2CO3 solutions of various concentrations (0.05 and 0.5 M). Doped samples were then tested in a TGA and a FBR for comparison of their reactivities in both cases. K2CO3 was found to harm the performance of the sorbents over the cyclic operation, as it provoked agglomeration and prevented fluidization in the FBR, whereas KCl-doped sorbents exhibited improved performance. A KCl concentration of 0.5 M was found to have an optimum effect on the performance of the limestones. The doping method was such that the dopant was largely confined to the surface of the sorbents. The observed improvements were associated with the reduced friability of the doped samples, as well as a fundamental improvement of the doped particles, as they exhibited increased reaction rates during the slow carbonation phase. Chen et al. (2013) doped limestone (particle size 125 μm) with attapulgite through hydration and DM. Carbonation experiments were conducted in a TGA to assess the CO2 uptake performance of the sorbents, while cyclic carbonation/calcination experiments were carried out in a twin FBR system to evaluate the cyclic performance of the sorbents. The carbonation reactivity of sorbents slightly improved after modifying with attapulgite by DM. The optimal content of attapulgite in limestone was 15 wt.% and it was found that higher percentages of attapulgite do not necessarily improve the CO2 uptake. Modified sorbents through hydration showed a significantly improved CO2 capture capacity. Sorbents doped with 15 wt.% attapulgite by hydration maintained a CO2 uptake of 0.68 g/g after 20 cycles, which is a 96% improvement over undoped limestone particles. TGA experiments showed that hydration-modified doped sorbents exhibited a longer-lasting kinetically controlled carbonation stage, producing a higher CO2 uptake. Doped sorbents maintained a Brenneur-Emmett-Teller (BET) surface area of about 17 m2/g after 15 carbonation and calcination cycles, compared to about 4 m2/g for the undoped limestone particles. Al-Jeboori et al. (2012) studied the effect of doping limestone (Havelock and Purbeck) with inorganic salts (e.g., MgCl2, CaCl2 and Mg (NO3)2) and Grignard reagent-isopropyl magnesium chloride using WI, quantitative WI (QWI), and DM. QWI combines the simplicity of DM and the homogeneous distribution of WI, producing well-mixed doped

176

Carbon Dioxide Capture and Conversion

sorbents while saving time compared to WI. Doped sorbents were tested in a lab-scale FBR (outer diameter 25.5 mm, length 543 mm, quartz tube) in cyclic carbonation and calcination experiments. It was found that the carrying capacity of Havelock doped with 0.05 M MgCl2 by WI was about 20% after 13 cycles, compared to about 10% for the unmodified Havelock. Doping Havelock with 0.165 mol% MgCl2 using QWI produced similar results with about 18% residual carrying capacity after 13 cycles. Increasing the concentration of the doping solution for WI to 0.5 M was found to negatively affect the carrying capacity, reducing the carrying capacity to about 8% after 13 cycles. The concentrations that showed the best results for Havelock were used to dope Purbeck limestone with the same dopants. The results showed no improvement in the case of MgCl2 and CaCl2 and only minor improvements in the case of Mg(NO3)2. Purbeck sorbents doped with magnesium nitrate exhibited a residual capacity of 16% compared to 14% for the unmodified Purbeck. González et al. (2016) investigated the synergetic effect of doping limestone with HBr and steam addition. Five limestones (e.g., Havelock, Longcliffe, Purbeck, Compostilla, and Cadomin) were sieved to a size fraction of 500
710 μm and doped with HBr using the QWI method. A solution of HBr in deionized water was prepared (2 cm3) and poured over 4 g of limestone and dried at 100°C in an oven. Cycling experiments were performed in a lab-scale FBR (internal diameter of 21 mm). Among undoped limestones, Purbeck and Compostilla exhibited the best results with a CO2-carrying capacity of about 15% after 13 cycles. Adding 10% steam during both carbonation and calcination improved the performance of all limestones, with Cadomin showing the greatest improvement, increasing the carrying capacity to 26% in comparison to 11% in the absence of steam. Doping the particles with 0.167 mol% HBr enhanced the carrying capacity of all sorbents, most significantly for Longcliffe limestone, which showed 22% conversion after 13 cycles, which is more than twice the conversion achieved for the undoped limestone. Effects of steam addition and sorbent doping were synergetic, increasing the carrying capacity of limestones by an average of three times higher than the baseline undoped samples without steam addition. Purbeck limestone showed the highest carrying capacity of 37% after 13 cycles. Doping and steam addition resulted in less pore structure deformation in the samples and a higher BET surface area after cycling. HBr-doped Longcliffe limestone maintained a BET surface area of 5.3 m2/g in the presence of steam, in comparison to 3.2 m2/g for undoped limestone in the absence of steam.

Application of calcium looping (CaL) technology for CO2 capture

177

Table 7.2 BET surface area of doped and undoped Longcliffe limestone in the presence and absence of steam. BET surface area (m2/g) Cycles

No steam, no HBr

10% steam, no HBr

No steam, HBr

10% steam, HBr

Calcination only 1 5 13

16.6 8.8 6.1 3.2

14.7 11.8 6.6 3.7

9.4 8.8 5.9 3.6

9.0 7.8 6.6 5.3

Source: Reproduced with permission from González, B., Blamey, J., Al-Jeboori, M.J., Florin, N.H., Clough, P.T., Fennell, P.S., 2016. Additive effects of steam addition and HBr doping for CaO-based sorbents for CO2 capture. Chemical Engineering and Processing: Process Intensification 103, 21
26.

Table 7.2 shows the BET surface area of doped and undoped Longcliffe limestone in the presence and absence of steam. Xu et al. (2017) doped limestone and mussel shells with sea salt by WI to improve the CO2-carrying capacity. Sorbents were screened to a particle size range of 200
300 μm before doping. A fixed quantity of salt (i.e., 0
2 wt.% sea salt to calcium precursor ratio) was dissolved in deionized water and then mixed with limestone or mussel shell particles. The mixture was stirred for 90 min at 80°C, followed by drying at 100°C in a dryer overnight. The cyclic CO2 capture performance of the sorbents was assessed in a fixed-bed reactor. Mussel shell sorbents doped with sea salt showed an increased uptake capacity of 0.167 g/g compared to 0.118 g/g for the unmodified shells. Improvement was also observed for the sea saltdoped limestone particles, increasing the uptake capacity from 0.168 to 0.240 g/g. The effect of the dopant’s mass ratio was studied by testing five different sea salt mass percentages in the modified sorbents. At lower dopant ratios (0.125 and 0.25 wt.%), sorbent reactivity dropped rapidly over cycles. However, at higher dopant percentages (0.5, 1.0, and 2.0 wt.%), sorbents exhibited a more stable uptake capacity over 20 cycles of carbonation and calcination. Findings indicated that a doping ratio of 0.25 wt.% produced optimum results in terms of CO2 capture capacity. 7.4.1.2 Chemical pretreatment Chemical pretreatment includes treating the sorbents with chemical agents that may react to some extent with the particles and potentially improve the CO2 capture performance. Researchers have studied treatment with

178

Carbon Dioxide Capture and Conversion

acetic acid, ethanol-water solution, propionic acid, formic acid, and suchlike. Acetic acid is an extensively studied chemical agent for the pretreatment of limestone and natural CaO-based sorbents (Li et al., 2008a,b, 2009). Li et al. (2009) treated limestone with a 50% acetic acid solution for 2 h, after which the mixture was dried at 120°C. The acetic acid-to-Ca molar ratio was 1.5:1. Modified sorbents were tested in a twin fixed-bed reactor system in cyclic carbonation and calcination experiments. Acetic acid-treated samples exhibited an improved conversion of 0.5 after 20 cycles in comparison to 0.15 for the original limestone particles. The enhancement of the CO2 uptake capacity was attributed to the smaller average grain size of particles produced from the acid-treated limestone, as well as the higher surface area and pore volume of the modified sorbent. The modified limestone also showed improved anti-sintering characteristics compared to the original limestone. Li et al. (2008a,b) modified limestone particles with ethanol/water solutions (50, 70, and 90% bulk concentration) and assessed the performance of the modified sorbents in a dual FBR system. The modified sorbents doubled the carbonation conversion (0.51) compared to the original limestone (0.25) after 15 cycles of carbonation/calcination. Samples treated with higher ethanol concentration in the solution exhibited higher resistance to sintering. It was proposed that the ethanol molecule enhanced the affinity of CaO to H2O molecules during the hydration reaction, resulting in expanded pores in the modified CaO after calcination. Wang et al. (2019) studied the treatment of limestone and dolomite with different acids (e.g., acetic acid, citric acid, and D-gluconic acid) and evaluated the carrying capacity of the resulting sorbents in a TGA under realistic conditions (high CO2 concentration during calcination). Treating a mixed limestone-dolomite sample (9:1 molar ratio) with acetic acid and citric acid produced particles of compositional homogeneity. However, this did not result in high CO2 uptake and stable sorbent. Sorbents exhibited agglomeration and structural collapse, which was attributed to the absence of void space for volume expansion over the carbonation period. Gluconic-acid-treated samples, however, produced a homogeneous mixture of CaO and MgO, providing sufficient void space for the volume expansion during carbonation. Samples modified with gluconic acid retained a CO2 uptake for 0.60 g/g after 10 cycles of carbonation and calcination under realistic conditions.

Application of calcium looping (CaL) technology for CO2 capture

179

Treatment of natural sorbents with chemical agents has been shown to enhance the CO2 uptake capacity and stability of the sorbents, as well as their sintering resistance and surface properties. However, considering the low cost of natural sorbents such as limestone, the additional cost of treatment must be considered when assessing the performance of these sorbents in real-life applications. An economic analysis of practical industrial processes employing calcium looping may prove the efficacy of using sorbents pre-treated with chemical agents. 7.4.1.3 Incorporation of sintering-resistant supports As sorbents go through repeated cycles, their structure deteriorates because of the sintering in response to the variations in molar density during carbonation and calcination and exposure to high temperatures, inducing the growth of CaO grains. Therefore, researchers have investigated the incorporation of supports with high Tammann Temperatures into the structure of sorbents to reduce the sintering effect at high temperatures. Tammann temperature is the point at which solid molecules acquire sufficient energy to initiate sintering. Tammann temperature is approximately half of the melting point of a substance (in Kelvin). Calcium aluminate cement has a melting point of 1535°C and a Tammann temperature of approximately 771°C (Sarrión et al., 2018), which is relatively higher than that of calcium carbonate (533°C; Chen et al., 2018). Therefore, it has been investigated as a candidate support to improve the sintering resistance of natural sorbents. Manovic and Anthony (2009) incorporated calcium aluminate cement into hydrated lime (Cadomin limestone) in a 9:1 mass ratio. Limestone was calcined for 2 h at 850°C before hydration. Calcined limestone and cement were mixed while slowly adding water. The gel-like product was extruded through a 1 mm sieve, and the resulting pellets (0.8 mm diameter) were air-dried for 24 h. Sorbents were tested over 1000 cycles of carbonation and calcination in a TGA. Larger pellets (10 mm diameter) were tested in a tube furnace for assessment of pellet mechanical strength. Calcium aluminate incorporated sorbents retained a residual conversion of 28% after 1000 cycles compared to 16% for the original limestone. Mechanical strength testing revealed that larger pellets exhibited major resistance loss during carbonation and calcination cycles, likely because of the formation of large cracks in the particles. Smaller particles that are more suitable for use in FBRs did not suffer from these cracks and exhibited better mechanical strength. Characterization experiments, including scanning

180

Carbon Dioxide Capture and Conversion

electron microscopy (SEM) and BET/BJH analyses, were performed, and it was observed that calcium aluminate incorporated pellets showed improved resistance to sintering and loss of small pores that are suitable for carbonation. Radfarnia and Iliuta (2013) investigated the stabilization of acidified natural limestones (Newfoundland and Graymont) with four metal oxide stabilizers (M: Al, Zr, Mg, and Y). The limestone was initially treated with citric acid, and the metal stabilizer was incorporated into the structure of the sorbent by simple wet mixing. Sorbents were tested in a TGA apparatus over cyclic experiments under mild and severe calcination conditions. Under mild operating conditions, a molar ratio of 0.1 (M/Ca, M Zr, Al) exhibited the best activity for Zr- and Al-stabilized samples produced from Newfoundland limestone. Sorbents produced from soluble zirconoxy nitrate and insoluble aluminum acetate showed optimum performance with uptake capacities of 0.29 g/g (41.1% CaO molar conversion) and 0.33 g/g (43.2% CaO molar conversion) after 25 cycles for Zr- and Al-stabilized sorbents, respectively. For Mg-stabilized sorbents, a molar ratio of 0.4 was found to produce optimum sorbents, with the uptake of 0.28 g/g (50.1% CaO molar conversion) after 25 cycles. The type of precursor (soluble or insoluble) was found to have a profound effect on the dispersion of the stabilizer, and subsequently, the activity of the sorbent. Under severe calcination conditions, samples stabilized from soluble Zr precursor with an M/Ca ratio of 0.1 exhibited the best activity and stability. Stabilizing natural sorbents by the incorporation of sintering-resistant supports is an effective method for the improvement of the performance of natural sorbents. Metal stabilizers also enhance the sorbents in mechanical strength and attrition resistance, in distinction to doping and chemical pretreatment. Zr-stabilized sorbents have shown better performance in comparison to other metal stabilizers. However, the high cost of Zr precursors puts forth Al-stabilized sorbents as a more practical option. It must also be noted that supported sorbents have a reduced inherent CO2-carrying capacity because of the smaller fraction of active CaO in the sorbent. Therefore, there is a trade-off between the stabilization effect and the reduction in the carrying capacity that must be considered when preparing such sorbents. Among different techniques for the stabilization of natural calcium oxide, another promising technique has been proposed known as coreshell (Sedghkerdar et al., 2014). In this technique, CaO is used in the core

Application of calcium looping (CaL) technology for CO2 capture

181

of the core-shell structured sorbent and is shelled with various compositions such as silica/zirconia or pure zirconia and different shell thicknesses (1
5 μm) (Sedghkerdar et al., 2016). The core
shell-structured pelletized sorbents having a B1 μm mesoporous zirconia shell exhibited a CO2 uptake of B7.2 moles CO2 per kg sorbent in TGA and the lowest activity loss of only 30.8% after 20 cycles. The sorbent stabilization was attributed to the thermally stable zirconium species on the core’s surface to avoid the aggregation and overgrowth of CaO crystals and prevent sorbent sintering. In comparison to the silica-shelled sorbents, zirconiashelled sorbents showed improved performance. In addition, the mesoporous zirconia-shelled sorbent showed an enhanced attrition resistance by testing sorbent with an air-jet apparatus.

7.4.2 Synthetic sorbents Natural CaO-based sorbents offer the advantage of low cost and wide availability. However, the substantial drop in the CO2-carrying capacity over cycles requires a significant purge of unreactive material and replacement of the unreactive sorbents with fresh ones. One of the first studies on calcium carbonate and calcium oxide reactions was conducted by Barker (1973). Barker demonstrated that natural CaCO3 (limestone) goes through complete conversion under calcination reaction conditions, producing CaO. However, the produced CaO does not go through complete carbonation, and the reverse reaction ceases at a conversion below unity. This was further studied by Bhatia and Perlmutter (1983), who proposed that this is because of the closure of narrow pores as a result of the significant difference between the molar densities of CaCO3 (Mv 36.9 cm3/mol) and CaO (Mv 16.9 cm3/mol). The lower Tammann temperature of CaCO3 (533°C) with respect to the common process temperatures (carbonation at 600°C
700°C and calcination at 850°C
950°C) results in the thermal sintering of the sorbents, which in turn, reduces the CO2 uptake capacity over cycles. SEM images of the changes in the morphology of natural sorbents over carbonation and calcination cycles are shown in Fig. 7.6. The rate of drop in the uptake capacity decreases with increasing cycle number until it reaches a residual value, after which it remains almost constant. As efforts were made to stabilize and improve the uptake capacity of natural CaO-based sorbents, researchers were simultaneously exploring

182

Carbon Dioxide Capture and Conversion

Figure 7.6 SEM images of Rheinkalk limestone (A) unreacted; (B) after 90 cycles (Broda and Müller, 2014).


the production of synthetic CaO-based sorbents that offer enhanced stability and CO2-carrying capacity. In this section, we will discuss the advances in the production of synthetic CaO-based sorbents for the calcium looping process. Researchers have explored two general strategies to produce synthetic sorbents, which are: 1. Production of unsupported CaO-based sorbents from different calcium precursors and material fabrication techniques. 2. Production of supported CaO-based sorbents with higher Tammann temperatures and thermal resistance. 7.4.2.1 Unsupported CaO-based sorbents The carrying capacity of CO2 sorbents largely depends on the morphology and the available surface area of the sorbent. Higher surface area prolongs the fast carbonation region resulting in a higher CO2-carrying capacity. Therefore, researchers have attempted synthesizing CaO sorbents that possess high surface area and porosity to achieve higher uptake capacity and stability. The surface area of the sorbent varies significantly with changes in the calcium precursor and the method of synthesis. In general, sorbents derived from organometallic precursors show higher initial conversion compared to the ones derived from inorganic metallic precursors (Liu et al., 2010; Luo et al., 2012). In a study by Lysikov et al. (2007), it was discovered that the structure of the CaO and the residual CaO carrying capacity is dependent on the type of calcium precursor used. Lu et al. (2006) synthesized CaO sorbents from four different precursors, Ca(NO3)20.4H2O, CaO, Ca(OH)2, and

Application of calcium looping (CaL) technology for CO2 capture

183

Ca(CH3COO)2.H2O, and tested them in a TGA system for CO2-carrying capacity assessment. They concluded that sorbents produced from calcium acetate precursor exhibited the greatest CO2-carrying capacity and stability over carbonation and calcination cycles. Samples produced from calcium acetate precursor maintained a CaO carbonation conversion of 93% after 10 cycles in the presence of 10% water vapor in the feed gas. After the 10th cycle, conversion began to reduce, dropping to 63% after 27 cycles. This high conversion was attributed to the large BET surface area and pore volume of the sorbent. SEM images of the calcium acetateproduced sorbents showed a porous, “fluffy” structure, whereas sorbents produced from calcium hydroxide looked more compact and solid (Fig. 7.7). This fluffy structure resulted in the high surface area of the sorbent and has also been reported by researchers as producing sorbents using the combustion synthesis method (Hashemi et al., 2020). The effect of the addition of refractory silica to the sorbent’s structure was also studied but showed no enhancement in the performance of the sorbent. The authors concluded that the principal reason for the reduction in the carbonation conversion is blockage of pores rather than sintering of the sorbents. In another study, Lu et al. (2008a,b) tested CaO sorbents produced from different organometallic precursors, namely, calcium propionate, calcium acetate, calcium acetylacetonate, calcium oxalate, and calcium 2-ethylhexanoate, through a simple calcination method in which the precursor was heated to a temperature of 900°C and held there for 1 h under air atmosphere. Results indicated that sorbents produced from calcium

Figure 7.7 SEM images of sorbents derived from (A) calcium acetate; (B) calcium hydroxide.


184

Carbon Dioxide Capture and Conversion

propionate and calcium acetate precursors showed the highest CO2carrying capacity. The improved performance of the sorbents was attributed to the high surface area and pore volume. Decomposition of the aforementioned precursors (calcium propionate and calcium acetate) produced large macropores, which improved the structural properties of the sorbent. On the other hand, sorbents produced from calcium oxalate and calcium 2-ethylhexanoate precursors showed poor performance because of the microporous structure of the sorbents. These micropores were blocked after initial carbonation, as the formation of calcium carbonate caused an increase in the volume of the sorbent, thus blocking the narrow micropores. Aside from the calcium precursor, the method of synthesis also contributes to the surface properties and structure of the sorbent. Several synthesis methods have been studied by researchers, including coprecipitation, solgel, flame spray pyrolysis, and solution combustion synthesis. Lu et al. (2009) produced CaO using the flame spray pyrolysis technique. They dissolved a calcium naphthenate precursor in xylene and fed the solution in a spray nozzle, which was then ignited in a premixed flame. The resultant sorbent exhibited a surface area of 40
60 m2/g and a particle size of 30
50 nm. Nitrogen adsorption surface measurements and SEM images confirmed the nanosized particle structure characterized by the high surface area. The synthetic sorbent retained an uptake capacity of 0.38 g/g after 50 cycles of carbonation and calcination under mild conditions (700°C and pure helium atmosphere), which is only a slight improvement over CaO derived from calcium acetate. Luo et al. (2013) produced CaO particles through the sol-gel technique using citric acid as the chelating agent. The cyclic performance of the sorbents was assessed in a tube furnace having two compartments, i.e., a carbonation reactor and a calcination reactor. The reaction kinetics were tested in a TGA. The synthetic sorbent exhibited a well-developed pore structure that resulted in an uptake capacity of 0.51 g/g in mild calcination conditions (800°C, N2 purge) and 0.20 g/g in harsh calcination conditions (950°C and CO2 purge) after 20 cycles. The enhanced pore structure also improved the kinetics of the reaction, as the sorbent reached 60% CaO conversion within 20 s of initiating carbonation. 7.4.2.2 Supported CaO-based sorbents As stated previously in the case of natural sorbents, CaO suffers from a loss of surface area because of the thermal sintering of the sorbent

Application of calcium looping (CaL) technology for CO2 capture

185

resulting in the low Tammann temperature of CaCO3. Therefore, incorporating supports with higher Tammann temperatures may enhance the sintering resistance of sorbents. Table 7.3 shows the Tammann temperature for commonly used supports. Researchers have investigated the addition of Al2O3, MgO, ZrO2, TiO2, etc. to CaO-based sorbents as supports. As indicated in Table 7.3, these compounds have higher Tammann temperatures in comparison to CaCO3 and may improve the sorbent’s structural strength. Some compounds may form mixed oxides with CaO, such as ZrO2, which forms the mixed oxide CaZrO3. The mixed oxide may have a different Tammann temperature from the original metal oxide. Therefore, characterization experiments such as XRD are required to determine the crystallinity and phase formation of the solid sorbents. Kierzkowska et al. (2013) produced Al2O3-stabilized Ca-based sorbents through coprecipitation. They found that the main factors contributing to the morphology and chemical composition of the sorbent are the calcium precursor and the precipitating base used for the synthesis. The precipitation pH had a minor effect in comparison to the aforementioned factors. The sorbent obtained from Ca(NO3)2 as the calcium precursor and (NH4)2CO3 as the precipitating base at a pH of 9.7 showed the best performance retaining a CO2 uptake capacity of 0.36 g CO2/g sorbent after 30 cycles, under mild calcination conditions (750°C and N2 purge), and 0.31 g CO2 /g sorbent after 10 cycles, under severe calcination Table 7.3 Tammann temperature (Tt) of CaO, CaCO3, and commonly used stabilizers. Compound

Tt (°C)

Reference

CaO CaCO3 Al2O3 Ca3Al2O6 Ca12Al14O33 TiO2 CaTiO3 SiO2 Ca2SiO4 ZrO2 CaZrO3 MgO Y2O3

1170 533 900 771 725 785 851 664 929 1221 1036 1276 1083

Zhao et al. (2014) Chen et al. (2018) Zhao et al. (2014) Sarrión et al. (2018) Zhao et al. (2014) Zhao et al. (2014) Zhao et al. (2014) Zhao et al. (2014) Su et al. (2018) Zhao et al. (2014) Zhao et al. (2014) Sarrión et al. (2018) Zhang et al. (2014)

186

Carbon Dioxide Capture and Conversion

conditions (925°C and CO2 purge). When calcium acetate and ammonium carbonate were used as the calcium precursor and the precipitating base, respectively, SEM images showed the formation of CaCO3 in the form of vaterite, whereas using sodium carbonate as the precipitating base produced CaCO3 in the form of calcite. For the optimum sorbent produced from calcium nitrate precursor and ammonium carbonate precipitator, both calcite and vaterite were detected, and the highest surface area and pore volume were achieved. A more comprehensive study on Al2O3-stabilized CaO sorbents produced from various synthesis techniques was conducted by Wang et al. (2018). Al2O3-stabilized sorbents with different mass ratios were produced through wet mixing, coprecipitation, and sol-gel auto-combustion synthesis techniques. Calcium and aluminum nitrate [Ca(NO3)20.4H2O and Al(NO3)30.9H2O] were used as the precursor for each metal. The cyclic performance of the sorbent was tested in a fixed-bed reactor system (diameter of 50 mm and 1200 mm long). The best CO2-carrying capacity and stability were observed for the sorbents produced through the sol-gel auto-combustion technique with a Ca to Al mass ratio of 75:25 (Fig. 7.8).

Figure 7.8 Cyclic performance of sorbents developed by Wang et al. (2018). SG-CaO and SG-75:25 represent samples produced through sol-gel synthesis without support (SG-CaO) and with 75:25 Ca to Al support ratio (SG-75:25), respectively.




Application of calcium looping (CaL) technology for CO2 capture

187

The effect of Al2O3 was most pronounced for the sorbents derived from wet mixing, improving both the uptake capacity and the stability (sample denoted as SG-75:25). However, for the sorbents produced through coprecipitation and sol-gel techniques, the addition of Al2O3 reduced the CO2 capture capacity but positively impacted the stability of the sorbent. SG-75:25 showed a CO2 uptake capacity of 0.275 g CO2/g sorbent and about 0.26 g CO2/g sorbent after 30 cycles, under mild (900°C and pure N2) and severe (950°C and pure CO2 purge) calcination conditions, respectively. Wang et al. (2018) also investigated the structural differences of the synthetic sorbents. Sorbents produced from different synthesis routes exhibited similar structural units of tetrahedral Al site (AlO4) but displayed peaks characterized by different intensity and broadness in their Al NMR spectra. Sorbents produced from coprecipitation and sol-gel techniques had a more disordered structure because of the presence of fivefold and octahedral Al. The stability of the sorbent was affected by the tetrahedral coordinated AlO4 with a broad signal. However, the CO2 uptake capacity of the sorbent was more influenced by the octahedral coordinated AlO6 located on the surface of the particle. As the sorbent went through multiple carbonation and calcination cycles, AlO4 converted to AlO6. The presence of AlO6 in the used sorbents improved their cyclic stability, whereas AlO4 reduced the sintering resistance. The inert support in the sorbents was detected in three forms of Al2O3, Ca12Al14O33, and Ca3Al2O6, depending on the synthesis method used to produce the sorbent. Interaction of ZrO2 with CaO is simpler compared to Al2O3, only forming CaZrO3 mixed oxide. When a high mass ratio of ZrO2 is used, sorbents display much-improved stability in cyclic operation. However, a high ZrO2 ratio reduces the active CaO fraction, which results in a lower CO2 uptake capacity. Therefore, a compromise must be made between the amount of stabilizer and the drop in the uptake capacity. Hashemi et al. (2020) produced ZrO2-stabilized CaO sorbents through the solution combustion synthesis method using urea as fuel. Sorbents were analyzed in a TGA for assessment of the uptake capacity and cyclic stability. A mass ratio of 10% for CaZrO3 was found to produce optimum uptake capacity and stability results. After 50 cycles, sorbents retained an uptake capacity of 0.39 g CO2/g sorbent under mild calcination conditions (850°C and pure N2 purge) and 0.29 g CO2/g sorbent under severe calcination conditions (950°C and pure CO2 purge). The presence of CaZrO3 had a positive effect on the BET surface area of the sorbents.

188

Carbon Dioxide Capture and Conversion

When the mass ratio of CaZrO3 increased from 10% to 20%, the BET surface area increased from 15.6 to 19.6 m2/g. This was displayed in the increased conversion of the sorbents with a higher CaZrO3 percentage. Synthetic sorbents exhibited homogeneous distribution of CaZrO3 support in the sorbent, which contributes to the high stability of the particles (Fig. 7.9).

7.5 Kinetics modeling of calcium looping process The prediction of the CaO particles’ performance through developing the kinetic models would be highly beneficial. The CaL process proceeds as a noncatalytic exothermic reaction, which involves the fast kinetic controlling step and mass transfer limitation step. Generally, after a critical thickness of the carbonate layer, the rate of carbonation decreases sharply because of changing from kinetic controlling step to mass transfer or diffusion step as mentioned above. The critical thickness of the CaCO3 layer was reported in the range of 38
70 nm (Bouquet et al., 2009; Wu and Lan, 2012). The order of reaction was reported to vary between zero- and firstorder for the intrinsic rate parameters depending on the CO2 partial pressures (Khoshandam et al., 2010; Li et al., 2012). It was estimated that the order of reaction changes from one to zero depending on CO2 pressures. Therefore, at low CO2 pressures (PCO2 1 bar), the reaction order is one and at higher pressures zero, respectively (Liu et al., 2012). The activation energy was found not to change significantly with the sorbents’ textural characteristics in the fast carbonation step. However, this parameter depends on their surface morphology while the carbonate deposit

Figure 7.9 Energy-dispersive X-ray spectroscopy (EDX) elemental mapping showing the homogeneous distribution of stabilizer in the synthetic sorbent.

Application of calcium looping (CaL) technology for CO2 capture

189

builds up, controlling the gas diffusion to the inner active core (Lee, 2004). This section reviews the proposed kinetic models used for calcium oxide sorbents in both described steps. A variety of kinetic models were introduced to determine the reaction rate of CaO sorbents’ carbonation. The most conventional model developed to describe the reaction between gas and solid particle is the shrinking core model (SCM) (Yagi and Kunii, 1955). In this model, the particle is described as a nonporous sphere, and as the reaction goes forward, the reacting particles consume or shrink. SCM is extensively applied to estimate kinetic parameters in gas-solid reactions because of its simplicity. Generally, this model postulates that the reaction occurs on an outer layer of a particulate solid particle and propagates into an inner layer, while a product layer forms progressively. This infers the existence of an unreacted core, which shrinks during the reaction. The reaction mechanism of SCM is proposed in three fundamental steps for carbonation conversion: 1. Diffusion of CO2 from the gas layer built over a solid surface. 2. CO2 transfer via the carbonate deposition on the surface to access the active solid particle. 3. Carbonation of the active CaO available at the particle surface. Despite the popularity of the model, it is not able to accurately predict low conversion values of sorbents and may overestimate the conversion in sorbents that show a high conversion at elevated temperatures (Blamey et al., 2016). The following equations show the kinetic and diffusion control regions of carbonation, respectively, based on SCM.  ρr
1 ð1 X ðt ÞÞ3 t (7.7) ks C t

ρr 2 h 1 6DC

2

3ð1 X ðt ÞÞ3

2ð1

i X ðt ÞÞ

(7.8)

In Eqs. (7.7) and (7.8), t is the time (s), ρ and r show the density and radius of CaO (kg/m3, m), respectively, ks is the reaction rate coefficient (m4/mol/s), C is the gas concentration (mol/m3), X(t) is the conversion, and D is the diffusion constant of the product layer (m2/s). Owing to the limitations of SCM, other models such as the random pore model (RPM) and the grain model (GM) were developed afterward to improve the accuracy of the predictions. The RPM assumes that the pore topologies are comprised of disordered interlinked pores in which

190

Carbon Dioxide Capture and Conversion

reactions occur at constant temperature (Bhatia and Perlmutter, 1980). In RPM, the reaction behavior is related to the internal pore structure. In addition, the driving forces for the reactions are structural parameters and CO2 partial pressure. RPM seems precise in estimating the calcium oxide carbonation performance; however, it is considered a complex model because it requires structural parameters (Grasa et al., 2014). This model has been modified several times to express the CaO performance while the two carbonation steps change sharply as discussed above. In one of the modifications, a new stage (the transition stage) was defined (Jiang et al., 2016). This modified model presented a satisfactory data fitting of the measured results. The kinetic and diffusion regions in the RPM are displayed in the following equations, respectively (Fedunik-Hofman et al., 2019): i k S tðC C Þ 1 hpffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi s 0 b e 1 ψlnð1 XðtÞÞ 1 (7.9) ψ 2ð1 ε0 Þ 1 hpffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 1 ψlnð1 XðtÞÞ ψ

i 1

qffiffiffiffiffiffiffiffiffiffiffiffiffiffi S0 2ð1

MCaO DCt 4:352ρ

ε0 Þ

(7.10)

In Eqs. (7.9) and (7.10), ψ is a structural parameter, obtained by using Eq. (7.11): ψ

4πL0 ð1 ε0 Þ S02

(7.11)

In the above equations, S0 is the initial surface area per volume (m2/m3), Cb and Ce represent CO2 concentrations in gas and at equilibrium state, respectively, ε0 is the initial porosity of CaO, MCaO is the molar mass of CaO (kg/mol), L0 is the pore length per volume (m/m3), and other parameters are defined the same as the SCM model. In GM, each particulate is composed of globular nonporous calcium oxide grain domains, which are randomly positioned within the solid, and the carbonate shell is deposited over the external surface of each domain (Szekely and Evans, 1970). In this model, two factors of the initial solid diffusion coefficient and grain size were reported to influence conversion. The decrease of the first factor (initial solid diffusion coefficient) enhances a fast transfer of the CO2 inside the particle to improve the carbonation conversion (Stendardo and Foscolo, 2009). The second factor influences the reaction interface. Grains with smaller sizes expose more surface areas,

Application of calcium looping (CaL) technology for CO2 capture

191

thus enhancing the overall conversion. The GM or overlapping grain model (OGM) is founded on the dispersion of micro-grains in the continuous gas phase (Sedghkerdar and Mahinpey, 2019). Whereas, in RPM, the solid phase was considered the continuous phase. The diffusion coefficients and the rate constants which are estimated by the RPM model show inferior values than OGM predicated values because of neglected effects of carbonate layer diffusion and surface reaction on the RPM kinetic controlling step. Based on the assumption of the GM model, the product layer diffusion coefficient is very high; thus, CO2 can easily penetrate through the deposited layer and reach the pristine calcium oxide. In addition, the gas film diffusion resistance around the particle is assumed negligible (Sedghkerdar and Mahinpey, 2015). OGM model reflects both the fast kinetic and diffusion-controlling stages altogether in the carbonation reaction (Sedghkerdar and Mahinpey, 2019). The conversion of particles is shown by the following equation in GM (Sun et al., 2008a,b). dX 2

dtð1 X ðt ÞÞ3

3k

(7.12)

where k is the rate constant for GM. The integral form of the equation is shown in the following formula: h i 1 1 ð1 XðtÞ Þ3 kt (7.13) Other kinetic models were also introduced to define the kinetic behavior of gas-solid, including nucleation and apparent models (Fedunik-Hofman et al., 2019). In the nucleation model, it is assumed that a sigmoidal relationship exists between sorbent’s conversion and time (Li et al., 2012). The following equations display two significant controlling steps (i.e., the kinetic and diffusion control) for the nucleation model, respectively: Fn

kn ðCb

Ce ÞNmolecular 

Di

D0i exp

Ei RT

(7.14)

 (7.15)

where Fn and kn represent the nucleation rate (mol m3/s) and dimensionless coefficient, respectively. Nmolecular is the Avogadro’s number, T is the temperature, and D0i and Di are the initial and isothermal diffusion constants, respectively. Finally, the apparent model uses a simple semiempirical

192

Carbon Dioxide Capture and Conversion

approach to describe the kinetic behavior of the particles (Li et al., 2012). Eq. (7.16) displays the conversion of CaO to CaCO3 according to this model (Lee, 2004). Xu shows the ultimate conversion of CaO to CaCO3.    k X ðt Þ Xu 1 exp t (7.16) Xu X ðt Þ

Xt Xu u k

t

(7.17)

7.6 Conclusions and perspectives In this chapter, we reviewed different techniques for the improvement of calcium oxide behavior in the CaL process. Despite numerous advantages of CaO, such as high theoretical capturing capacity, low cost, the possibility of industrial application, environmental benefits, flexibility for using fluidized reactors, and the possibility for utilizing the sintered calcium oxide in the cement industry, it suffers from several issues. Attrition and sintering of the sorbent particles and unfavorable side reactions of CaO with impurities in the flue gas significantly reduce the overall efficiency of the process. Therefore, different methods were proposed to address these issues. Doping, incorporation of supports, and chemical pretreatment were suggested to improve the capturing capacity and recyclability of naturally occurring sorbents (e.g., limestone, dolomite, lime mud, etc.). Among these, chemical pretreatment is the costliest method and makes a shortterm impact on the sorbent’s stability because it does not use structural stabilizers. Thus, doping and application of different supports are considered to significantly improve the natural calcium oxides’ performance. However, it should be noted that sorbents prepared by doping might have a low capturing capacity under severe industrial operating conditions. There are also challenges in the use of supported sorbents. Generally, the capturing capacity of the supported CaO is less than the unmodified CaO because of a reduction of the active material in the sorbent. Incorporation of sintering resistant supports diminishes the activity loss and enhances the attrition resistance over carbonation/calcination cycles. In this regard, sorbents produced by using Zr- and Al-based materials exhibited significant improvements with respect to mechanical resistance and attrition

Application of calcium looping (CaL) technology for CO2 capture

193

tolerances compared to unmodified sorbents. However, Zr-stabilized sorbents are more expensive and less efficient than the Al-stabilized sorbents, although the former shows better cyclic performance. Besides advances in improving natural sorbents’ performance, several effective techniques were proposed to fabricate synthetic calcium oxides sorbents. In addition, a variety of support materials were suggested to improve the structure of synthetic sorbents. However, the capturing capacity of synthetic CaO has been observed to reduce over multiple cycles under actual industrial conditions, which was attributed to the lack of using structural stabilizers in their synthesis method. It should be noted that calcium precursors and synthesis methods are important factors determining the efficacy and economic viability of the synthesized calcium oxide sorbents. Supporting synthetic CaO with materials possessing high Tammann temperature enhances and stabilizes the sorbent’s multicycle operation to some extent; however, the additional cost of support’s incorporation (material and synthesis cost) should be considered. The side reactions between CaO and flue gas impurities cannot be prevented easily by modifying the sorbent’s structure, as some impurities (e.g., SO2) have a very strong affinity toward CaO. Therefore, impurities should be separated from the flue gas prior to introducing the gas to the CCS facilities. In conclusion, the CaL process is a fast-evolving technology, which has substantial potential for post- or pre-combustion CO2 capture. Significant progress has been achieved to enable the CaL process to be integrated with other promising processes such as CLC, thermal storage applications, hydrogen production, CO2 conversion to valueadded products, energy/power generation from renewables, and cement production. The overall technology readiness level (TRL) of CaL is assessed 8-9, as it has been demonstrated in several pilot-scale facilities around the globe. The major issues hindering the rapid advancement in the large-scale applications of CaL are mentioned below. Currently, researchers propose novel techniques to synthesize highly efficient CaO-based sorbents; however, most of these techniques ignore the synthesis cost, environmental benignity, and complexity of the synthesis method, which is essential for the further improvement of this technology and should be considered in their research. In addition, most of the lab-scale experiments are conducted with powdered sorbents and under mild operating conditions versus industrial settings. Typically, powdered sorbents or nanoparticles exhibit good performance in lab-scale tests. However, for industrial applications, pelletized or granular sorbents are

194

Carbon Dioxide Capture and Conversion

utilized. Pelletization of powdered sorbents reduces their capturing capacity. Besides, sorbents under mild conditions exhibit better sintering and attrition resistance performance compared to severe industrial conditions. Considering these points will accelerate the large-scale industrial application of the CaL process in the near future.

References Abanades, J.C., 2002. The maximum capture efficiency of CO2 using a carbonation/calcination cycle of CaO/CaCO3. Chemical Engineering Journal 90 (3), 303
306. Al-Jeboori, M.J., Fennell, P.S., Nguyen, M., Feng, K., 2012. Effects of different dopants and doping procedures on the reactivity of CaO-based sorbents for CO2 capture. Energy and Fuels 26 (11), 6584
6594. Alvarez, D., Abanades, J., 2005. Determination of the critical product layer thickness in the reaction of CaO with CO2. Industrial and Engineering Chemistry Research 44 (15), 5608
5615. Anthony, E.J., Granatstein, D.L., 2001. Sulfation phenomena in fluidized bed combustion systems. Progress in Energy and Combustion Science 27 (2), 215
236. Arias, B., Grasa, G.S., Abanades, J.C., 2010. Effect of sorbent hydration on the average activity of CaO in a Ca-looping system. Chemical Engineering Journal 163 (3), 324
330. Arias, B., Abanades, J.C., Anthony, E.J., 2011a. Model for self-reactivation of highly sintered CaO particles during CO2 capture looping cycles. Energy and Fuels 25 (4), 1926
1930. Arias, B., Abanades, J.C., Grasa, G.S., 2011b. An analysis of the effect of carbonation conditions on CaO deactivation curves. Chemical Engineering Journal 167 (1), 255
261. Arias, B., Grasa, G.S., Alonso, M., Abanades, J.C., 2012. Post-combustion calcium looping process with a highly stable sorbent activity by recarbonation. Energy and Environmental Science 5 (6), 7353
7359. Arias, B., Diego, M.E., Abanades, J.C., Lorenzo, M., Diaz, L., Martínez, D., et al., 2013. Demonstration of steady state CO2 capture in a 1.7MWth calcium looping pilot. International Journal of Greenhouse Gas Control 18, 237
245. Barker, R., 1973. Reversibility of the reaction CaCO3 CaO CO2. Journal of Applied Chemistry and Biotechnology 23 (10), 733
742. Bhatia, S.K., Perlmutter, D.D., 1980. A random pore model for fluid-solid reactions: I. Isothermal, kinetic control. AIChE Journal 26 (3), 379
386. Bhatia, S.K., Perlmutter, D.D., 1983. Effect of the product layer on the kinetics of the CO2-lime reaction. AIChE Journal 29 (1), 79
86. Blamey, J., Anthony, E.J., Wang, J., Fennell, P.S., 2010a. The calcium looping cycle for large-scale CO2 capture. Progress in Energy and Combustion Science 36 (2), 260
279. Blamey, J., Paterson, N.P.M., Dugwell, D.R., Fennell, P.S., 2010b. Mechanism of particle breakage during reactivation of CaO-based sorbents for CO2 capture. Energy and Fuels 24 (8), 4605
4616. Blamey, J., Zhao, M., Manovic, V., Anthony, E.J., Dugwell, D.R., Fennell, P.S., 2016. A shrinking core model for steam hydration of CaO-based sorbents cycled for CO2 capture. Chemical Engineering Journal 291, 298
305. Boot-Handford, M.E., Abanades, J.C., Anthony, E.J., Blunt, M.J., Brandani, S., Mac Dowell, N., et al., 2014. Carbon capture and storage update. Energy and Environmental Science 7 (1), 130
189.

Application of calcium looping (CaL) technology for CO2 capture

195

Borgwardt, R., 1989. Sintering of nascent calcium oxide. Chemical Engineering Science 44 (1), 53
60. Bouquet, E., Leyssens, G., Schönnenbeck, C., Gilot, P., 2009. The decrease of carbonation efficiency of CaO along calcination-carbonation cycles: experiments and modelling. Chemical Engineering Science 64 (9), 2136
2146. Broda, M., Müller, C.R., 2014. Sol-gel-derived, CaO-based, ZrO2-stabilized CO2 sorbents. Fuel 127, 94
100. Charitos, A., Rodríguez, N., Hawthorne, C., Alonso, M., Zieba, M., Arias, B., et al., 2011. Experimental validation of the calcium looping CO2 capture process with two circulating fluidized bed carbonator reactors. Industrial and Engineering Chemistry Research 50 (16), 9685
9695. Chen, H., Zhao, C., Li, Y., Chen, X., 2010. CO2 capture performance of calcium-based sorbents in a pressurized carbonation/calcination loop. Energy and Fuels 24 (10), 5751
5756. Chen, H., Zhao, C., Chen, M., Li, Y., Chen, X., 2011. CO2 uptake of modified calcium-based sorbents in a pressurized carbonation-calcination looping. Fuel Processing Technology 92 (5), 1144
1151. Chen, H., Zhao, C., Yu, W., 2013. Calcium-based sorbent doped with attapulgite for CO2 capture. Applied Energy 112, 67
74. Chen, J., Duan, L., Donat, F., Müller, C.R., Anthony, E.J., Fan, M., 2018. Self-activated, nanostructured composite for improved CaL-CLC technology. Chemical Engineering Journal 351, 1038
1046. Chen, J., Duan, L., Sun, Z., 2020. Review on the development of sorbents for calcium looping. Energy & Fuels 34 (7), 7806
7836. Cook, J.L., Khang, S.J., Lee, S.K., Keener, T.C., 1996. Attrition and changes in particle size distribution of lime sorbents in a circulating fluidized bed absorber. Powder Technology 89 (1), 1
8. Coppola, A., Montagnaro, F., Salatino, P., Scala, F., 2012a. Attrition of limestone during fluidized bed calcium looping cycles for CO2 capture. Combustion Science and Technology 184 (7
8), 929
941. Coppola, A., Montagnaro, F., Salatino, P., Scala, F., 2012b. Fluidized bed calcium looping: the effect of SO2 on sorbent attrition and CO2 capture capacity. Chemical Engineering Journal 207
208, 445
449. Dean, C.C., Blamey, J., Florin, N.H., Al-Jeboori, M.J., Fennell, P.S., 2011. The calcium looping cycle for CO2 capture from power generation, cement manufacture and hydrogen production. Chemical Engineering Research and Design 89 (6), 836
855. Dennis, J.S., Pacciani, R., 2009. The rate and extent of uptake of CO2 by a synthetic, CaO-containing sorbent. Chemical Engineering Science 64 (9), 2147
2157. Diego, M.E., Arias, B., Alonso, M., Abanades, J.C., 2013. The impact of calcium sulfate and inert solids accumulation in post-combustion calcium looping systems. Fuel 109, 184
190. Erans, M., Manovic, V., Anthony, E.J., 2016. Calcium looping sorbents for CO2 capture. Applied Energy 180, 722
742. Fedunik-Hofman, L., Bayon, A., Donne, S.W., 2019. Kinetics of solid-gas reactions and their application to carbonate looping systems. Energies 12 (15), 2981. Fennell, P.S., Pacciani, R., Dennis, J.S., Davidson, J.F., Hayhurst, A.N., 2007. The effects of repeated cycles of calcination and carbonation on a variety of different limestones, as measured in a hot fluidized bed of sand. Energy and Fuels 21 (4), 2072
2081. González, B., Blamey, J., McBride-Wright, M., Carter, N., Dugwell, D., Fennell, P., et al., 2011. Calcium looping for CO2 capture: sorbent enhancement through doping. Energy Procedia 4, 402
409. González, B., Blamey, J., Al-Jeboori, M.J., Florin, N.H., Clough, P.T., Fennell, P.S., 2016. Additive effects of steam addition and HBr doping for CaO-based sorbents for

196

Carbon Dioxide Capture and Conversion

CO2 capture. Chemical Engineering and Processing: Process Intensification 103, 21
26. Grasa, G.S., Abanades, J.C., 2006. CO2 capture capacity of CaO in long series of carbonation/calcination cycles. Industrial and Engineering Chemistry Research 45 (26), 8846
8851. Grasa, G., Martínez, I., Diego, M.E., Abanades, J.C., 2014. Determination of CaO carbonation kinetics under recarbonation conditions. Energy and Fuels 28 (6), 4033
4042. Hashemi, S.M., Karami, D., Mahinpey, N., 2020. Solution combustion synthesis of zirconia-stabilized calcium oxide sorbents for CO2 capture. Fuel 269, 117432. He, S., Hu, Y., Hu, T., Ma, A., Jia, Q., Su, H., et al., 2017. Investigation of CaO-based sorbents derived from eggshells and red mud for CO2 capture. Journal of Alloys and Compounds 701, 828
833. Huang, Y.F., Lee, Y.T., Chiueh, P.T., Lo, S.L., 2018. Microwave calcination of waste oyster shells for CO2 capture. Energy Procedia 152, 1242
1247. Huertas, J.I., Gomez, M.D., Giraldo, N., Garzón, J., 2015. CO2 absorbing capacity of MEA. Journal of Chemistry 2015, 1
7. Hughes, R.W., Lu, D., Anthony, E.J., Wu, Y., 2004. Improved long-term conversion of limestone-derived sorbents for in situ capture of CO2 in a fluidized bed combustor. Industrial and Engineering Chemistry Research 43 (18), 5529
5539. Jiang, L., Hu, S., Syed-Hassan, S.S.A., Wang, Y., Shuai, C., Su, S., et al., 2016. Performance and carbonation kinetics of modified CaO-based sorbents derived from different precursors in multiple CO2 capture cycles. Energy and Fuels 30 (11), 9563
9571. Khoshandam, B., Kumar, R., Allahgholi, L., 2010. Mathematical modeling of CO2 removal using carbonation with CaO: the grain model. Korean Journal of Chemical Engineering 27 (3), 766
776. Kierzkowska, A.M., Poulikakos, L.V., Broda, M., Müller, C.R., 2013. Synthesis of calcium-based, Al2O3-stabilized sorbents for CO2 capture using a co-precipitation technique. International Journal of Greenhouse Gas Control 15, 48
54. Kunze, C., Spliethoff, H., 2012. Assessment of oxy-fuel, pre- and post-combustion-based carbon capture for future IGCC plants. Applied Energy 94, 109
116. Lee, D.K., 2004. An apparent kinetic model for the carbonation of calcium oxide by carbon dioxide. Chemical Engineering Journal 100 (1
3), 71
77. Li, Y., Zhao, C., Duan, L., Liang, C., Li, Q., Zhou, W., et al., 2008a. Cyclic calcination/ carbonation looping of dolomite modified with acetic acid for CO2 capture. Fuel Processing Technology 89 (12), 1461
1469. Li, Y.J., Zhao, C.S., Qu, C.R., Duan, L.B., Li, Q.Z., Liang, C., 2008b. CO2 capture using CaO modified with ethanol/water solution during cyclic calcination/carbonation. Chemical Engineering & Technology 31 (2), 237
244. Li, Y., Zhao, C., Chen, H., Liang, C., Duan, L., Zhou, W., 2009. Modified CaO-based sorbent looping cycle for CO2 mitigation. Fuel 88 (4), 697
704. Li, Z., Sun, H., Cai, N., 2012. Rate equation theory for the carbonation reaction of CaO with CO2. Energy and Fuels 26 (7), 4607
4616. Lisbona, P., Martínez, A., Romeo, L.M., 2013. Hydrodynamical model and experimental results of a calcium looping cycle for CO2 capture. Applied Energy 101, 317
322. Liu, H., Wu, S., 2019. Preparation of high sorption durability nano-CaO-ZnO CO2 adsorbent. Energy and Fuels 33 (8), 7626
7633. Liu, W.G., Low, N.W.L., Feng, B., Wang, G., Diniz Da Costa, J.C., 2010. Calcium precursors for the production of CaO sorbents for multicycle CO2 capture. Environmental Science and Technology 44 (2), 841
847. Liu, W., Dennis, J.S., Sultan, D.S., Redfern, S.A.T., Scott, S.A., 2012. An investigation of the kinetics of CO2 uptake by a synthetic calcium based sorbent. Chemical Engineering Science 69 (1), 644
658.

Application of calcium looping (CaL) technology for CO2 capture

197

Lu, H., Reddy, E.P., Smirniotis, P.G., 2006. Calcium oxide based sorbents for capture of carbon dioxide at high temperatures. Industrial and Engineering Chemistry Research 45 (11), 3944
3949. Lu, D.Y., Hughes, R.W., Anthony, E.J., 2008a. Ca-based sorbent looping combustion for CO2 capture in pilot-scale dual fluidized beds. Fuel Processing Technology 89 (12), 1386
1395. Lu, H., Khan, A., Smirniotis, P.G., 2008b. Relationship between structural properties and CO2 capture performance of CaO-based sorbents obtained from different organometallic precursors. Industrial and Engineering Chemistry Research 46 (17), 6216
6220. Lu, H., Smirniotis, P.G., Ernst, F.O., Pratsinis, S.E., 2009. Nanostructured Ca-based sorbents with high CO2 uptake efficiency. Chemical Engineering Science 64 (9), 1936
1943. Luo, C., Shen, Q., Ding, N., Feng, Z., Zheng, Y., Zheng, C., 2012. Morphological changes of pure micro- and nano-sized CaCO3 during a calcium looping cycle for CO2 capture. Chemical Engineering and Technology 35 (3), 547
554. Luo, C., Zheng, Y., Zheng, C., Yin, J., Qin, C., Feng, B., 2013. Manufacture of calcium-based sorbents for high temperature cyclic CO2 capture via a sol-gel process. International Journal of Greenhouse Gas Control 12, 193
199. Lyngfelt, A., Leckner, B., 1989. Sulphur capture in fluidized bed boilers: the effect of reductive decomposition of CaSO4. The Chemical Engineering Journal 40 (2), 59
69. Lysikov, A.I., Salanov, A.N., Okunev, A.G., 2007. Change of CO2 carrying capacity of CaO in isothermal recarbonation-decomposition cycles. Industrial and Engineering Chemistry Research 46 (13), 4633
4638. Ma, A.H., Jia, Q.M., Su, H.Y., Zhi, Y.F., Tian, N., Wu, J., et al., 2016. Study of CO2 cyclic absorption stability of CaO-based sorbents derived from lime mud purified by sucrose method. Environmental Science and Pollution Research 23 (3), 5477
5484. Ma, X., Li, Y., Chi, C., Zhang, W., Wang, Z., 2017. CO2 capture performance of cementmodified carbide slag. Korean Journal of Chemical Engineering 34 (2), 580
587. Ma, Z., Li, Y., Zhang, W., Wang, Y., Zhao, J., Wang, Z., 2020. Energy storage and attrition performance of limestone under fluidization during CaO/CaCO3 cycles. Energy 207, 118291. MacDowell, N., Florin, N., Buchard, A., Hallett, J., Galindo, A., Jackson, G., et al., 2010. An overview of CO2 capture technologies. Energy and Environmental Science 3 (11), 1645
1669. Manovic, V., Anthony, E.J., 2009. Long-term behavior of CaO-based pellets supported by calcium aluminate cements in a long series of CO2 capture cycles. Industrial and Engineering Chemistry Research 48 (19), 8906
8912. Martínez, I., Grasa, G., Murillo, R., Arias, B., Abanades, J.C., 2013. Modelling the continuous calcination of CaCO3 in a Ca-looping system. Chemical Engineering Journal 215
216, 174
181. Mostafavi, E., Mahinpey, N., Rahman, M., Sedghkerdar, M.H., Gupta, R., 2016. Highpurity hydrogen production from ash-free coal by catalytic steam gasification integrated with dry-sorption CO2 capture. Fuel 178, 272
282. Perejón, A., Romeo, L.M., Lara, Y., Lisbona, P., Martínez, A., Valverde, J.M., 2016. The Calcium-Looping technology for CO2 capture: on the important roles of energy integration and sorbent behavior. Applied Energy 162, 787
807. Radfarnia, H.R., Iliuta, M.C., 2013. Metal oxide-stabilized calcium oxide CO2 sorbent for multicycle operation. Chemical Engineering Journal 232, 280
289. Ramkumar, S., Fan, L.S., 2010. Calcium looping process (CLP) for enhanced noncatalytic hydrogen production with integrated carbon dioxide capture. Energy and Fuels 24 (8), 4408
4418. Rodriguez, N., Alonso, M., Grasa, G., Abanades, J.C., 2008. Heat requirements in a calciner of CaCO3 integrated in a CO2 capture system using CaO. Chemical Engineering Journal 138 (1
3), 148
154.

198

Carbon Dioxide Capture and Conversion

Rodriguez, N., Alonso, M., Abanades, J.C., Charitos, A., Hawthorne, C., Scheffknecht, G., et al., 2011. Comparison of experimental results from three dual fluidized bed test facilities capturing CO2 with CaO. Energy Procedia 4, 393
401. Ryu, H.J., Grace, J.R., Lim, C.J., 2006. Simultaneous CO2/SO2 capture characteristics of three limestones in a fluidized-bed reactor. Energy and Fuels 20 (4), 1621
1628. Salvador, C., Lu, D., Anthony, E.J., Abanades, J.C., 2003. Enhancement of CaO for CO2 capture in an FBC environment. Chemical Engineering Journal 96 (1
3), 187
195. Sarrión, B., Perejón, A., Sánchez-Jiménez, P.E., Pérez-Maqueda, L.A., Valverde, J.M., 2018. Role of calcium looping conditions on the performance of natural and synthetic Ca-based materials for energy storage. Journal of CO2 Utilization 28, 374
384. Sedghkerdar, M.H., Mahinpey, N., 2015. A modified grain model in studying the CO2 capture process with a calcium-based sorbent: a semianalytical approach. Industrial and Engineering Chemistry Research 54 (3), 869
877. Sedghkerdar, M.H., Mahinpey, N., 2019. Modified overlapping grain size distributed model for the kinetic study of CO2 capture by a synthetic calcium-based sorbent: structural changes from the chemical reaction and sintering. Industrial and Engineering Chemistry Research 58 (31), 14000
14007. Sedghkerdar, M.H., Mahinpey, N., Sun, Z., Kaliaguine, S., 2014. Novel synthetic sol-gel CaO based pellets using porous mesostructured silica in cyclic CO2 capture process. Fuel 127, 101
108. Sedghkerdar, M.H., Mahinpey, N., Soleimanisalim, A.H., Sun, Z., Chen, Z., Lim, J., et al., 2016. Core-shell structured CaO-based pellets protected by mesoporous ceramics shells for high-temperature CO2 capture. The Canadian Journal of Chemical Engineering 94 (11), 2038
2044. Shan, S.Y., Ma, A.H., Hu, Y.C., Jia, Q.M., Wang, Y.M., Peng, J.H., 2016. Development of sintering-resistant CaO-based sorbent derived from eggshells and bauxite tailings for cyclic CO2 capture. Environmental Pollution 208, 546
552. Shimizu, T., Hirama, T., Hosoda, H., Kitano, K., Inagaki, M., Tejima, K., 1999. A twin fluid-bed reactor for removal of CO2 from combustion processes. Chemical Engineering Research and Design 77 (1), 62
68. Silaban, A., Harrison, D.P., 1995. High temperature capture of carbon dioxide: characteristics of the reversible reaction between CaO (s) and CO2 (g). Chemical Engineering Communications 137 (1), 177
190. Stendardo, S., Foscolo, P.U., 2009. Carbon dioxide capture with dolomite: a model for gas-solid reaction within the grains of a particulate sorbent. Chemical Engineering Science 64 (10), 2343
2352. Su, C., Duan, L., Donat, F., Anthony, E.J., 2018. From waste to high value utilization of spent bleaching clay in synthesizing high-performance calcium-based sorbent for CO2 capture. Applied Energy 210, 117
126. Sun, P., Grace, J.R., Lim, C.J., Anthony, E.J., 2007a. Removal of CO2 by calcium-based sorbents in the presence of SO2. Energy and Fuels 21 (1), 163
170. Sun, P., Grace, J.R., Lim, C.J., Anthony, E.J., 2007b. The effect of CaO sintering on cyclic CO2 capture in energy systems. AIChE Journal 53 (9), 2432
2442. Sun, P., Grace, J.R., Lim, C.J., Anthony, E.J., 2008a. Determination of intrinsic rate constants of the CaO-CO2 reaction. Chemical Engineering Science 63 (1), 47
56. Sun, P., Lim, C.J., Grace, J.R., 2008b. Cyclic CO2 capture by limestone-derived sorbent during prolonged calcination/carbonation cycling. AIChE Journal 54 (6), 1668
1677. Sun, R., Li, Y., Liu, C., Xie, X., Lu, C., 2013. Utilization of lime mud from paper mill as CO2 sorbent in calcium looping process. Chemical Engineering Journal 221, 124
132. Sun, J., Yang, Y., Guo, Y., Xu, Y., Li, W., Zhao, C., et al., 2018. Stabilized CO2 capture performance of wet mechanically activated dolomite. Fuel 222, 334
342.

Application of calcium looping (CaL) technology for CO2 capture

199

Szekely, J., Evans, J.W., 1970. A structural model for gas-solid reactions with a moving boundary. Chemical Engineering Science 25 (6), 1091
1107. Valverde, J.M., Sanchez-Jimenez, P.E., Perez-Maqueda, L.A., 2014a. Role of precalcination and regeneration conditions on postcombustion CO2 capture in the Ca-looping technology. Applied Energy 136, 347
356. Valverde, J.M., Sanchez-Jimenez, P.E., Perez-Maqueda, L.A., Quintanilla, M.A.S., PerezVaquero, J., 2014b. Role of crystal structure on CO2 capture by limestone derived CaO subjected to carbonation/recarbonation/calcination cycles at Ca-looping conditions. Applied Energy 125, 264
275. Wang, J., Manovic, V., Wu, Y., Anthony, E.J., 2010. A study on the activity of CaObased sorbents for capturing CO2 in clean energy processes. Applied Energy 87 (4), 1453
1458. Wang, T.H., Xiao, D.C., Huang, C.H., Hsieh, Y.K., Tan, C.S., Wang, C.F., 2014. CO2 uptake performance and life cycle assessment of CaO-based sorbents prepared from waste oyster shells blended with PMMA nanosphere scaffolds. Journal of Hazardous Materials 270, 92
101. Wang, N., Feng, Y., Liu, L., Guo, X., 2018. Effects of preparation methods on the structure and property of Al-stabilized CaO-based sorbents for CO2 capture. Fuel Processing Technology 173, 276
284. Wang, K., Gu, F., Clough, P.T., Zhao, P., Anthony, E.J., 2019. CO2 capture performance of gluconic acid modified limestone-dolomite mixtures under realistic conditions. Energy and Fuels 33 (8), 7550
7560. Wu, S.F., Lan, P.Q., 2012. A kinetic model of nano-CaO reactions with CO2 in a sorption complex catalyst. AIChE Journal 58 (5), 1570
1577. Xu, Y., Luo, C., Zheng, Y., Ding, H., Zhou, D., Zhang, L., 2017. Natural calcium-based sorbents doped with sea salt for cyclic CO2 capture. Chemical Engineering & Technology 40 (3), 522
528. Yagi, S., Kunii D., 1955. Studies on Combustion of Carbon Particles in Flames and Fluidized Beds (pp. 231
236). The 5th Symposium (International) on Combustion, New York, USA. Zhang, X., Li, Z., Peng, Y., Su, W., Sun, X., Li, J., 2014. Investigation on a novel CaOY2O3 sorbent for efficient CO2 mitigation. Chemical Engineering Journal 243, 297
304. Zhang, Y., He, L., Ma, A., Jia, Q., He, S., Shan, S., 2018. CaO-based sorbent derived from lime mud and bauxite tailings for cyclic CO2 capture. Environmental Science and Pollution Research 25 (28), 28015
28024. Zhao, M., Shi, J., Zhong, X., Tian, S., Blamey, J., Jiang, J., et al., 2014. A novel calcium looping absorbent incorporated with polymorphic spacers for hydrogen production and CO2 capture. Energy and Environmental Science 7 (10), 3291
3295.

CHAPTER 8

Dry reforming of methane and biogas to produce syngas: a review of catalysts and process conditions Zahra Alipour, Venu Babu Borugadda, Hui Wang and Ajay K. Dalai Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada

Abbreviations ALD CNT CCVD CA DRB DRM GHSV IWI LDH MSC MWCNT PS PM RWGS SCS TPD TPO TPR UH

Atomic layer deposition Carbon nanotube Catalytic chemical vapor deposition Citric acid Dry reforming of biogas Dry reforming of methane Gas hourly space velocity Incipient wetness impregnation Layered double hydroxide Mesoporous silica-carbon Multiwalled carbon nanotubes Pechini sol-gel Physical mixing Reverse water
gas shift Solution combustion synthesis Temperature-programmed desorption Temperature-programmed oxidation Temperature-programmed reduction Urea hydrolysis

8.1 Introduction Biogas is considered a renewable and ecofriendly gaseous biofuel, which is abundantly available for the generation of electrical and heat energy. Biogas could also be generated via the decomposition of biomass and methanogenic bacterial degradation in the absence of air (Nanda et al., 2016). The main components of biogas are CH4 (50%
75%) and CO2 (25%
50%) (2%
8% other gases such as H2O(g), N2, O2, S2, and H2S), Carbon Dioxide Capture and Conversion DOI: https://doi.org/10.1016/B978-0-323-85585-3.00003-1

© 2022 Elsevier B.V. All rights reserved.

201

202

Carbon Dioxide Capture and Conversion

which are appropriate to produce syngas with higher hydrogen (Rosset et al., 2020). Dry reforming of biogas (DRB) is the same as dry reforming of methane (Eq. 8.1), which is highly endothermic (Aouad et al., 2018). Dry reforming of methane (DRM) is a widely used process to produce syngas using undesirable greenhouse gases such as CH4 and CO2 (Nguyen et al., 2020). Moreover, these greenhouse gases are abundantly accessible for reforming reactions (Jang et al., 2019).  kJ CH4 CO2 2CO 2H2 ΔH 247 (8.1) mol In the case of the reforming process (Eq. 8.1), the H2/CO ratio is 1, which is suitable for Oxo and Fischer-Tropsch processes. However, reverse water
gas shift (RWGS) (Eq. 8.2) reaction leads to H2/CO ratio of less than 1. Furthermore, rapid coke formation because of CH4 decomposition (Eq. 8.3) occurs at 600°C
800°C, and Boudouard reactions (Eq. 8.4) takes place at 250°C
350°C that leads to catalysts deactivation and reactor blockage, which are the major challenges in dry reforming of methane (Macario et al., 2019).  kJ CO2 H2 CO H2 O ΔH 41 (8.2) mol  CH4

2CO

C

C

2H2 ΔH  CO2 ΔH

kJ 75 mol



kJ 172 mol

(8.3) (8.4)

In general, three types of carbons are formed during dry reforming processes i.e., active carbon species (that react with oxygen at low temperatures), amorphous and/or graphite forms of carbon, and filamentous forms of carbon (Aziz et al., 2019). It has been reported that the type of catalysts plays a remarkable role in the conversion of methane and biogas and the coke deposition (Singh et al., 2018). Among the several reforming catalysts, group VIII noble metal-based catalysts are known to be active and stable catalysts for the dry reforming reactions, and the order of metal activity was found to be Ru  Rh Ir Pt Pd (Aziz et al., 2019). As these metals are rare and expensive, several efforts have been made to find alternate metals that are inexpensive and available.

Dry reforming of methane and biogas to produce syngas

203

Nonnoble metals, including Ni, were found to be the most common metal used in dry reforming processes (Abidin et al., 2020). Furthermore, bimetallic catalysts like Ni-Co and Ni-Mo are highly recommended because of more active sites, culminating in better nickel dispersion and lower carbon deposition (Aziz et al., 2019). It was also claimed that the role of support cannot be neglected in these processes as it affects the metal particle dispersion, oxygen vacancies, and metal-support interaction as well as the porosity of the catalysts. Various supports such as SiO2, Al2O3, MgO, CeO2, ZrO2, and TiO2 have been investigated in dry reforming, and promoters like alkaline and alkaline earth metals have been applied to boost catalytic activity, stability, and coke deposition (Bac et al., 2019). Carbon nanotubes (CNTs) and core-shell catalysts are being recently considered because of their higher catalytic activity, thermal conductivity, degree of porosity, and mechanical strength in dry reforming (Fu et al., 2007). Besides, process conditions, catalyst preparation methods, catalysts precursor, and type of reactors have been found effective in the catalytic performance of the DRM process. Catalyst preparation techniques and precursors can notably affect the interaction between metals and support as well as active phase dispersion, contributing better catalytic activity, stability, and less coke formation (Alipour et al., 2015; Aghamohammadi et al., 2017; Sudhakaran et al., 2018; Al-Fatesh et al., 2019). This review discusses dry reforming of methane and biogas in-depth, studies and compares different catalysts, and evaluates the role of promoters, precursors, and process conditions to understand their impact on catalytic activity, sustainability, and coke deposition.

8.2 Heterogeneous catalyst for dry reforming 8.2.1 Noble metal-based catalyst Different noble metal catalysts used in DRM and biogas are listed in Table 8.1 with various preparation methods, reaction conditions, and precursors used. Reported studies have shown that group VIII noble metalbased catalysts are active and stable for DRM (Sudhakaran et al., 2018; Al-Fatesh et al., 2019). Furthermore, it was noticed that the carbon deposition during a reforming reaction varies based on the type of active metals used. Transition metals, such as Ni, Pt, Ru, Pd, and Rh, are active for CO2 reforming of methane. Aziz et al. (2019) reported that the scope of carbon deposition on the aforementioned metals is interrelated to their

Table 8.1 Supported noble metal catalysts for dry reforming. Catalyst Support

Pd

γ-Al2O3, 8 mol% Y2O3 stabilized ZrO2 (YSZ: Zr0.92Y0.08O2 δ), 10 mol% Gd2O3 doped CeO2 (GDC: Ce0.9Gd0.1O2 δ) CeO2

Pd

Hydroxyapatite

Pt

Al2O3

Pt, Ru

MgO-Al2O3, ZrO2-Al2O3, CeO2-Al2O3, and La2O3Al2O3

Ir

Preparation method

Process conditions

Precursor

Reference

Wet impregnation

400°C
850°C, 12 h, GHSV: 9000, 11,000 and 18,000 L/g/h

IrCl3

Yentekakis et al. (2015)

PdCl2 Pd(NO3)2

Singha et al. (2017) Kamieniak et al. (2017)

Platinum(II) bis (acetylacetonate)

Li et al. (2015)

Hexachloroplatinic acid (H2PtCl6), acidic ruthenium (III) chloride hydrate (RuCl3  xH2O)

Carvalho et al. (2014)

Single-step surfactant 350°C, 12 h induced method Ultrasound-assisted Feed: 100 mL/min ion exchange (IE) comprising CH4: CO2:He equal to and incipient 5:5:90, 0.2 gcat, 200°C wetness and 650°C impregnation (IWI) 700°C, 18 h, 1 atm, CH4/CO2/N2: 1:1:8, GHSV: 120, 240 L/gcat/ h Incipient wetness 650°C with a 1:1:1 impregnation molar ratio of CH4: CO2:N2 gas mixture (IWI)

Pt, Ru

Pyrochlore

Modified Pechini method

Rh, Ru, Pt, Pd, Ir (1 wt. %)

Alumina

Wet impregnation

600 min, 50 mg catalyst, Ruthenium chloride (RuCl3) or hydroGHSV: 48,000 mL/ chloroplatinic acid gcat/h [H2PtCl6  (H2O)6] Pd(NH3)4(NO3)2, Pt 600°C, 2 h, GHSV: (NH3)4(NO3)2, Rh 16,000 L/kgcat/h, 150 mg catalyst (NH3)6(NO3)3, IrCl3, and Ru(NO) (NO3)3

Pakhare et al. (2013) Nematollahi et al. (2011)

206

Carbon Dioxide Capture and Conversion

activity for CO2 separation. Their study concluded that Ru and Rh showed higher catalytic activity for CO2 separation with insignificant carbon deposition during DRM (Aziz et al., 2019). Nematollahi et al. (2011) confirmed that Rh and Ru supported on MgAl2O4 catalysts had higher methane conversion in DRM compared to other noble catalysts (Fig. 8.1) because of their better reducibility. On the other hand, at high temperatures, sintering takes place for Ir, Pt, and Pd metals. Furthermore, all noble metal catalysts represented high stability during 50 h time on stream. The preparation of Ru/ CNT revealed that Ru could highly disperse on the CNT with small particle size, culminating in better catalytic activity in dry reforming (Fu et al., 2007; Hou et al., 2009). Further, the reactants would easily be accessible to the active sites on the metal-based catalyst with the CNTs support because of better dispersion of the active phase (Yadav, 2019). This study suggests that Rh and Ru-based catalysts have better catalytic performance in DRM because of better particle dispersion and reducibility compared to other noble metals.

8.2.2 Nonnoble metal-based catalysts Among the nonnoble metals, Ni-based catalysts are extensively used in dry reforming processes with various supports because of availability and lower cost compared to noble metals and show high carbon deposition and catalysts sintering in dry reforming (Aziz et al., 2019). Along with Ni,

Figure 8.1 (A) CH4 conversion and (B) CO2 conversion, dry reforming on the different noble metal catalysts [CH4/CO2 1, GHSV 16,000 mL/(h gcat)].

International Journal of Hydrogen Energy




Dry reforming of methane and biogas to produce syngas

207

other metals like Co have been studied and well understood in dry reforming. Mirzaei et al. (2015) investigated Co/MgO catalysts in DRM with various cobalt loadings of 5%
30%. Among them, 10% Co loading had the best stability compared to other catalyst concentrations (Fig. 8.2). The catalyst with a lower amount of Co was inactive because of insufficient active sites for reactants while the higher amount of Co blocked the catalysts’ pores and decreased metal dispersion. Therefore, optimization of active metal loading is significant to increase the catalytic stability and syngas production during dry reforming. Nonetheless, Ni-based catalysts suffer from deactivation because of coke formation in dry reforming, blocking active sites. Thus, bimetallic or promoted Ni catalysts aimed for better catalytic performance to overcome the current challenges. Akbari et al. (2017) evaluated the role of Ni loading in the catalytic activity and formation of coke for Ni-Mg-Al2O3 catalyst in DRM. During their study, along with an increase in Ni loading, CH4 and CO2 conversions are increased. Furthermore, coke deposition analysis illustrated that a higher amount of coke was deposited when the nickel content was increased, which could be assigned to lower Ni dispersion. Although Ni plays a significant contribution in the catalytic activity, the optimum amount of Ni can be effective in conversion and providing suitable active sites. Alipour et al. (2014a) observed the Ni reducibility and consumption of higher hydrogen when Ni concentration is increased owing to the lower Ni dispersion at high content of NiO. Rosha et al. (2019b) used

Figure 8.2 Time vs (A) CH4 and (B) CO2 conversion over CoMgO catalyst at CH4:CO2: 1:1, GHSV: 12,000 mL/(h gcat), temperature: 700°C.
Engineering Chemistry

Journal of Industrial and


208

Carbon Dioxide Capture and Conversion

pure Ni nanopowder in biogas dry reforming to evaluate its activity. The findings validated the high activity of Ni nanopowder in this process for H2 enrichment at higher temperatures (Rosha et al., 2019b). Further, core-shell nanocatalysts in DRM by Li et al. (2019a) showed a higher surface area with more active sites that led to a better catalytic activity. In other words, the confinement effect of core-shell type catalysts provides advantages like preventing sintering of active metals, boosting stability and coke resistance, strengthening core and shell interactions because a large contact interface led to increased catalytic activity owing to a high number of available active sites (Li et al., 2019a). Ni-CeO2/SiO2 is highly active in DRM, and the presence of CeO2 could help Ni dispersion and reduce coke formation. Encapsulated active phase with porous oxide layers could generally decrease sintering (Ashik et al., 2018). Similar results were observed for Ni/Al2O3, Ni/SiO2, and Ni/Mg-Al2O3 catalysts in which core-shell catalysts improved the coke resistance of the catalysts in the dry reforming process (Kang et al., 2011; Wang et al., 2016). Ni and Co are common nonnoble metal catalysts used in dry reforming of methane and biogas as shown in Table 8.2, and Ni is more active than Co in DRM because of better reducibility relative to Co.

8.2.3 Bimetallic catalysts Table 8.3 shows the various bimetallic catalysts used in reforming reactions. It has been reported that bimetallic catalysts could remarkably exhibit better catalytic performance compared to monometallic catalysts in dry reforming owing to the synergetic effect of bimetals on the support of metal dispersion and extra active sites (Jang et al., 2019). For example, Co, Fe, and Cu represented low catalytic activity when employed as a monometallic catalyst, while they could play a pivotal role as a bimetallic in dry reforming (Gao et al., 2018). The positive effects of Fe were evaluated on the catalytic activity of Ni on MgO during DRM. The results confirmed the coke resistance of NiFe ascribed to oxyphilicity of Fe, which resulted in more CO2 adsorbent and more oxygen coverage on the surface, contributing to carbon oxidation. As catalytic deactivation may occur in the presence of excess oxygen via oxidation of metals, Fe/Ni ratio played a considerable role in this process (Zhang et al., 2020). Wang et al. (2011) prepared a novel bimetallic catalyst with Mm a
Nn b
Al3 c
Mg2 d O(am/2 bn/2 (3/2)c d) formula where Mm and Nn are two transition metals selected from Ni, Co, Mo, Fe, Mn, Cu,

Table 8.2 Nonnoble metal catalysts used for the dry reforming reaction. Catalyst

Support Preparation method

Reaction conditions

Precursor

Reference

Co (5, 10, 15, 20 and 30 wt.%)

MgO

Co-precipitation

Co(NO3)2  6H2O

Mirzaei et al. (2015)

Ni

Al2O3

-

-

Li et al. (2015)

Ni (core-shell structures) Ni (core-shell structures)

SiO2

-

Nickel nitrate

SiO2

Ni (core-shell structures)

Zhang and Li (2015) Han et al. (2020)

Yolk-shell structured Ni Yolk-shell structured Ni and Ni

SiO2

Reverse micelle approach Microemulsion approach, wetness impregnation

50% CH4 and 50% CO2, 200 mg catalyst, GHSV: 12,000 mL/h/gcat, 550°C
700°C, 5h 700°C, 18 h, 1 atm, CH4/CO2/N2: 1:1:8, GHSV: 120 and 240 L/gcat/h 40 h, 850°C, 26.8% CO2/26.8 CH4%/46.4% He stream, 20 mg catalyst CH4/CO2/N2 or CH4/H2O/N2 (molar ratio: 3:3:4 and total flow rate of 50 mL/min), 100 mg catalyst, 30,000 mL/(gh), 823
1023 K 700°C, 30 h, 1 atm, CH4:CO2: 1:1, GHSV: 60 L/g/h Molar ratio of CH4/CO2: 1, 100 mg catalyst, molar ratio of CH4/CO2: 1, 600
750°C, 1 h

SiO2

Nickel nitrate

Ni(NO3)2  6H2O Nickel nitrate

Wang et al. (2016) Wang et al. (2016)

Table 8.3 Bimetallic catalysts for the dry reforming reaction. Catalyst

Support

10 (wt.%) Ni-3 (wt.%) Mn Al2O3

Preparation Method

Reaction Condition

Precursor

Reference

Sol-gel method, Wet impregnation Incipient wetness impregnation

700°C, CH4/CO2: 1/1, GHSV: 12,000 (mL/hUgcat), 200 mg

Mn(NO3)2U4H2O, Ni (NO3)2U6H2O

550°C
700°C, 200 mg catalyst, 5 and 15 h time-on-stream, CH4: CO2: 1:1, GHSV: 12,000 mL/h 650°C
850°C, 4 h, 80 mg, GHSV: 132 L/h/gcat and CH4/CO2: 1

Co(NO3)2  6H2O, and Ni (NO3)2  6H2O

Ramezani et al. (2018a) Mirzaei et al. (2014)

Co(NO3)2U6H2O, (NH4)6Mo7O24U4H2O, Mg(NO3)2U6H2O, CeO2, Ni(NO3)2  6H2O, Co(NO3)2  6H2O

Khavarian et al. (2015) Turap et al. (2020)

Ni(NO3)2.6H2O, Mo (NO3)2.5H2O, Fe (NO3)3  9H2O, and Pt (NH3)4.(NO3)2

Jawad et al. (2019)

Platinum (II) bis (acetylacetonate) Rhodium trichloride and hexachloroplatinic acid

Li et al. (2015) Ghelamallah and Granger (2014)

Bimetallic Ni-Co

MgO

Co-Mo-
MgO

MWCNTs Sol-gel technique, CCVD CeO2 Incipient wetness 600°C
850°C, atmospheric pressure coimpregnation and CH4/CO2: 1, (CH4/CO2/N2: 0.3:0.3:0.4), 0.5 g Al2O3Incipient wetness 550°C
700°C, 10 h, 1 bar, 300 mg CeO2 impregnation catalyst, CH4 and CH4/CO2: 50/ 50, flow rate: 60 mL/min, GHSV: 12,000 mL/ h

Ni, Ni-Co

Ni-based supported monometallic Mo, bimetallic Fe-Mo and Pt-Mo, and trimetallic Pt-Fe-Mo NiPt Rh-Pt

Al2O3 Al2O3La2O3

Incipient wetness 700°C, 18 h, 1 atm, CH4/CO2/N2: impregnation 1:1:8, GHSV: 120, 240 L/gcat/h Wet 300°C
900°C, CH4:CO2:He coimpregnation 10:10:80 vol.%, flow rate: 5 L/h

Dry reforming of methane and biogas to produce syngas

211

and Zn metals, and a b c d 1 and 0.001 a 0.8, 0.001 b 0.8, 0.1 c 0.99, 0.01 d 0.99. The activity test showed high CH4 conversion for bimetallic Ni-Co catalysts relative to other bimetallic catalysts. Turap et al. (2020) investigated the Co-Ni alloy supported on CeO2 as a bimetallic catalyst for DRM and the results revealed that adding Co in the Ni on CeO2 enhanced catalytic activity and reduced coke deposition. This is likely because the addition of Co enhances CO2 adsorption, and thus, the Co-O interaction culminates in the inhibition of coke deposition. In addition, Ni is supported to prevent Co from oxidizing; similar observations were noticed by Jawad et al. (2019). Mirzaei et al. (2014) used Ni-Co/MgO catalyst for DRM in which cobalt had the role of removing the carbon deposition from the catalyst. Based on recent studies, Ni/Co ratio showed a significant role in the catalytic activity of the bimetallic catalysts. Lower Co loading usually has a positive influence on the reactant conversions, whereas higher Co concentration culminates in lower activity and more coke deposition than that of the monometallic catalysts (Bian et al., 2017). The impact of Cu, Fe, and Co metals in the catalytic performance and coke deposition of Ni/Al2O3 catalysts were evaluated in DRM by Li et al. (2019b). Among them, Ni-Fe loaded on Al catalyst indicated the higher catalytic activity because of the formation of FeNi3 alloy during reduction, while Ni-Cu/Al2O3 had the lowest stability and the highest coke formation (Li et al., 2019b). Furthermore, Ni-Mn/Al2O3 bimetallic catalyst was evaluated in DRM to investigate the role of Mn in the catalytic activity of Ni/Al2O3 catalyst. Experimental outcomes revealed better catalytic activity and less coke formation for bimetallic catalysts compared to monometallic catalysts. This may be because of better Ni dispersion and smaller Ni particle size because of the addition of Mn. Furthermore, a moderate amount of Mn had a positive effect on the catalytic performance (Ramezani et al., 2018a). Identical studies were carried out and similar outcomes were confirmed by Wang et al. (2013) for Ni-Co bimetallic catalysts in DRM. Besides, bimetallic clusters of Pt-Ni inhibited the coke deposition and promoted the reducibility of Ni, which contributed to higher catalytic activity and stability for dry reforming compared to monometallic catalysts (Xie et al., 2019). Macario et al. (2019) found that adding Rh into the Ni-based catalysts improved the reducibility of Ni particles. This may be because of the collision between nickel and rhodium oxides during the thermal reduction that favors the reduction of nickel oxides by prereduced Rh particles. The

212

Carbon Dioxide Capture and Conversion

addition of Rh to Ni/Al2O3 catalyst revealed higher catalytic performance compared to Ni/Al2O3 monometallic catalyst in DRM. In summary, the addition of noble metals to Ni-based catalysts might help prevent oxidation of Ni and promote the reducibility of Ni, increasing the number of available active sites, which leads to the alteration of surface properties of Ni and improvement in catalytic activity. For example, the addition of Pt into Ni caused a moderate drop in the barrier energy of CO2 dissociation, leading to increased catalytic activity (Pakhare and Spivey, 2014; Bian et al., 2017). Based on the aforementioned studies, all bimetallic catalysts had better catalytic performance compared to monometallic catalysts. Co was the best candidate among the studied metals in catalytic modification owing to the strong interaction between Co and Ni (Wang et al., 2016). In summary, Ni and Co are widely used as active metals in DRM. It is reported that Ni remarkably improved Co reducibility, resulting in more active sites available for reactants.

8.3 Effects of supports In general, the support material of the catalyst may not be active, but it could participate during the reaction by interacting with active sites on the catalyst. Common supports used for dry reforming reactions are listed in Table 8.4. Aziz et al. (2019) found that the catalytic activity with metal loading is impacted by the type of catalyst support used, dispersion of active metal species, metal-support interaction, and oxygen vacancies. Mesoporous materials have recently gained extensive interest owing to their large surface area, uniformity in the pore size, and higher pore volume promoting active metals dispersed on supports and the elimination of mass transfer effects (Gao et al., 2018). Ni supported on oxide catalysts have been vastly investigated because of their physicochemical properties. Ni-oxide-based catalysts with various supports (e.g., SiO2, Al2O3, MgO, ZrO2, and TiO2) have been studied for DRM. The findings disclosed that the catalytic activity followed the order of NiO/Al2O3 Ni/MgO Ni/SiO2 Ni/ZrO2 Ni/TiO2 and that the change in the support material noticeably influenced the activity of the catalyst. The better performance in Ni-based catalyst supported on Al2O3 may be attributed to higher CO2 adsorption led by the nature of the catalyst support (Zhang et al., 2015). Chaudhary et al. (2020) found that Ni/MgAl2O4 had higher catalytic activity relative to Ni on Al2O3 in DRM with the same reaction

Table 8.4 Catalysts with different support for the dry reforming reaction. Catalyst Support

Preparation method

Ni Ni

Ni

Al2O3 and MgAl2O4 Al2O3, SiO2, MgO, CeO2 and ZnO

Ni

SiO2, TiO2 and ZrO2 CeO2, ZnO

Rh

CeO2

Reaction condition

Precursor

Reference

Incipient wet 1 bar, space-time: 2 g-h/mol of CH4, impregnation DRM (CH4:CO2:N2: 1:1:1) Wet 650°C
850°C, 12 h, simulated biogas (CH4/ impregnation CO2/N2: 2:2:1) flow rate: 50 mL/min, method GHSV: 15,000 mL/gcat/h 750°C, 100 h, 60,000 mL/gcat/h,

Ni(NO3)2.6H2O

Chaudhary et al. (2020) Gao et al. (2020)

Impregnation

650°C
900°C, 12 h, CH4/CO2: 1.5/1

Ni(NO3)2  6H2O

Hard template method

650°C, 21 h

Rh(NO3)3, Ce (NO3)3.6H2O

Ni(NO3)2  6H2O Metal nitrates

Zhang et al. (2015) Rosha et al. (2019a) Djinovi´c et al. (2012)

214

Carbon Dioxide Capture and Conversion

conditions because of lower acidity, strength, sintering resistance, and better Ni dispersion. The strong metal-support interaction could provide good dispersion of active metal and strong resistance to sintering. Rh catalysts with different supports (e.g., Al2O3, ZrO2, MgO, CeO2, TiO2, SiO2, and Y2O3) were developed and used in DRM. The experimental outcomes showed that MgO and γ-Al2O3 were better supports for Rh metal because of the strong metal-support interaction via the formation of solid solutions such as MgRh2O4 (Jang et al., 2019). Comparing the Al2O3 and MgAl2O4 supports with Ni loading in DRM have shown a stronger interaction between Ni and Al2O3, validating the higher conversion and stability (Wysocka et al., 2019). Ni-based catalysts with various supports (e.g., MgO, ZnO, CeO2, Al2O3, and SiO2) were prepared and used in the dry reforming of biogas. Experimental outcomes revealed that Ni/Al2O3 catalysts showed higher catalytic activity among the studied catalysts because of sturdy contact among active metals and catalyst supports, while it triggered the reactor blocking owing to carbon deposition in the long term. The catalyst with MgO support had a lower activity and higher thermal stability relative to Ni loaded on Al2O3, and the other three catalysts revealed weak activity in biogas dry reforming. Hence, Ni/MgO catalysts had the best catalytic activity (Fig. 8.3) (Gao et al., 2020). The impact of support morphology on the catalytic activity of unpromoted and Ce-promoted Ni on alumina supports (e.g., nanograins and

Figure 8.3 Conversion efficiencies for (A) CH4 and (B) CO2 for Ni supported on MgO, ZnO, CeO2, Al2O3, and SiO2 at 600°C
850°C for 1 h of reaction time and GHSV of 15,000 mL/h/gcat. Journal of Cleaner Production

Dry reforming of methane and biogas to produce syngas

215

nanofibers) was investigated in dry reforming of biogas. The TPR profiles of the prepared catalysts revealed that Ce-promoted catalyst with nanofiber morphology demands higher temperature for reduction, indicating the strong interaction between the support and active sites. In addition, the catalyst with nanofiber support also showed better catalytic activity relative to the catalyst with supported nanograins. It was concluded that the alumina surface properties play an essential role in making aluminasupported catalysts with higher catalytic activity. Nanofiber alumina has more mesoporosity and higher pore diameter, cultivating the dispersion of the Ni and Ce precursors throughout the preparation, culminating in the distribution of the metals and the creation of smaller particles. It was also demonstrated that Ce has similar effects; further, Ce-promoted Ni on alumina catalyst not only showed good stability for industrial applications in the long term, but it also had the lowest amount of coke deposition in this process. Moreover, the regeneration of the catalyst showed complete recovery of the catalyst. Thus, NiCe with nanofiber alumina could be used for commercial applications (Aouad et al., 2018). The impact of mixed supports of CeO2 and ZnO on the catalytic activity of Ni-based catalyst was investigated in BDR. The results evidenced that mixed support (Ni/CeO2-ZnO) had a positive effect on the catalytic activity and coke formation compared to Ni/CeO2 catalyst. However, it is reported that a moderate amount of the second support could notably boost the catalytic performance (Rosha et al., 2019a). It could be concluded that Al2O3 support was widely used as a support or core-shell in DRM because of high surface area resulting in better metal dispersion with smaller particle size.

8.4 Role of modifiers One of the main drawbacks of Ni catalysts in dry reforming processes is coke formation and catalyst sintering because of the Boudouard reaction and methane decomposition. Several attempts have been made to boost catalyst activity and decrease coke formation, one of them was to introduce promoters and modifiers into the catalysts. The alkaline, alkaline earth, and rare earth metals are common promoters used for dry reforming reactions as shown in Table 8.5. Alipour et al. (2014b) reported that the alkaline earth promoters such as MgO, CaO, and BaO dramatically improved the catalyst activity of Ni supported on Al2O3 in DRM, as shown in Fig. 8.4. This is likely because of enhancement in the basicity

Table 8.5 Promoters used for the dry reforming reaction. Catalyst Support

Promoter

Ni

Al2O3

MgO

Ni

Al2O3

Ni

Al2O3

Ni

Al2O3

Ni

Al2O3

Ni

MgSiO3

Pt

Al2O3

La2O3

Rh

Al2O3

La2O3

Preparation method

Reaction conditions

Coprecipitation 550°C
700°C, 700 min, 200 mg catalyst, CO2/CH4: 1 mol, GHSV: 1.8 104 mL/h/gcat MgO Wet 550°C
700°C, 200 mg, CH4/CO2: impregnation 1:1, GHSV: 12,000 mL/h/gcat MgO, CaO, Wet 550°C
700°C, 1400 min, CH4/CO2: and BaO impregnation 1:1, GHSV: 12,000 mL/h/gcat, 200 mg K2O, MgO, Microemulsion 250 min, CH4/CO2: 1, GHSV: CaO, and 18,000 mL/h/gcat BaO K2O

Wet 550°C
700°C, 1400 min, CH4/CO2: impregnation 1:1, GHSV: 12,000 mL/h/gcat, 200 mg CaO, MgO, Hydrothermal 700°C, 250 min, CH4/CO2: 1:1, and BaO method GHSV: 18,000 mL/gcat/h, 100 mg

Precursor

Reference

Nickel nitrate hexahydrate Ni (NO3)2  6H2O

Akbari et al. (2017)

Nickel nitrate

Alipour et al. (2014b) Alipour et al. (2014c)

NiN2O6.6H2O, MgN2O6.6H2O, CaN2O6.4H2O, BaN2O6 Ni(NO3)2  6H2O MgN2O6.6H2O, CaN2O6.4H2O, BaN2O6 KNO2 NiN2O6.6H2O, KNO2

Shiraz et al. (2016)

Alipour et al. (2015)

Sodium silicate, magnesium Ghods et al. nitrate, magnesium silicate, Ni (2016) (NO3)2  6H2O Wet 300°C
900°C, CH4:CO2:He: Hexachloroplatinic acid Ghelamallah impregnation 10:10:80 vol.%, total flow rate: 5 L/h and Granger (2014) Wet 300°C
900°C, CH4:CO2:He: Rhodium trichloride Ghelamallah impregnation 10:10:80 vol.%, total flow rate: 5 L/h and Granger (2014)

Dry reforming of methane and biogas to produce syngas

217

Figure 8.4 (A) CH4 and (B) CO2 conversion with temperature at CH4/CO2: 1:1, GHSV: 12,000 (mL/h/gcat). Fuel




of the catalysts, culminating in an increase in CO2 adsorption and inhibiting Boudouard reaction (2CO C CO2); as a result, the amount of coke formed significantly decreased by adding alkaline earth modifiers (Fig. 8.5). Identical studies were carried out by Ghods et al. (2016) validating the positive effects of promoters with the basic nature of the Ni supported on MgSiO3 catalysts. Modified Ni/mesoporous silica-carbon (MSC) catalyst with Ce and Ca displayed higher activity compared to those modified with Ce or Ca in DRM because of the higher quantity of available active sites. Sun et al. (2020) noticed the smaller Ni particle size for the catalysts promoted with a higher Ce/Ca ratio owing to the sturdier contact among catalyst support and active material, which hindered the active metal moment at high reaction temperatures. Calgaro and Lopez (2019) compared Mg, Li, Ca, La, Cu, Co, and Zn as modifiers in the Ni/Al2O3 catalysts in biogas dry reforming. According to their findings, La-promoted catalysts showed higher stability at 700°C because of different structures compared to other metals. Ramezani et al. (2018b) reported the influence of Mg promoter on the catalytic activity and coke formation of Ni-Mn/Al2O3 bimetallic catalysts in DRM. The results illustrated that Mg addition as a modifier decreased the deposited coke because of the basic nature of the catalyst, adsorbing more CO2 and inhibiting the Boudouard reaction. It was also noted that MgO-promoted catalysts displayed better stability compared to unpromoted bimetallic and monometallic catalysts. These experimental findings are in line with

218

Carbon Dioxide Capture and Conversion

Figure 8.5 TPO contours for (A) 5% Ni on Al2O3, (B) 5% Ni on 3% Mg
Al2O3, (C) 5% Ni on 3% Ca
Al2O3, and (D) 5% Ni on 3% Ba
Al2O3 catalysts. Fuel


Zhan et al. (2017), in which the positive role of MgO as a promoter for Ni supported on Al2O3 catalyst in DRB was noticed. Alipour et al. (2015) investigated the effects of K2O in the catalytic activity for the Ni/Al2O3 in DRM and showed higher catalytic activity and formation of coke owing to the basic nature of K2O, increased CO2 adsorption, decreased carbon deposition, and improved catalytic stability. The higher amount of modifier may cause pore blockage, consequently decreasing catalytic activity, while a lower amount may not modify the catalytic properties (Alipour et al., 2014b). Two modifying methods [adding La2O3 and citric acid (CA)] have been used to boost the catalytic activity of Ni supported on MgO-Al2O3 with a low concentration of active metal (2.5 wt.% Ni) in DRM and DRB. The reduction analysis proved that the addition of citric acid during impregnation improved the active metal and support interaction, while the La modifier shifted the reduction temperature toward the lower temperature compared to the catalysts without modifiers. Further, both modifying agents were used as promoters and reduced at the highest temperature. The catalytic tests showed that Ni (CA)/Mg-Al2O3 and Ni-La (CA)/Mg-Al2O3 had superior activity and stability compared to La promoted and unpromoted catalysts. CA-modified catalysts also demonstrated better coke resistance

Dry reforming of methane and biogas to produce syngas

219

compared to other studied catalysts. Therefore, Ni (CA)/Mg-Al2O3 and Ni-La (CA)/Mg-Al2O3 catalysts exhibited low Ni loading with the highest catalytic activity and carbon resistance in DRM and DRB reactions (Ha et al., 2019). In summary, MgO and CeO2 have shown better promotional property in DRM because of higher basic nature and O2 vacancy property, contributing to more CO2 adsorption and less coke deposition.

8.5 Role of preparation methods The catalyst preparation method has a significant impact on the interaction between catalyst active sites and the support. Currently, sol-gel, impregnation (incipient and wet), precipitation, coprecipitation, surfactant-assisted, polyol, and atomic layered deposition methods are practiced to prepare dry reforming catalysts. Among several catalyst preparation techniques, the solgel technique is favored because of durable active metal and support interactions and smaller particle size for dry reforming reactions. It is also explained that precipitated catalysts have lower catalytic activity and stability relative to those prepared with the impregnation and sol-gel techniques, which has been attributed to the lower quantity of active sites and partial oxidation of Ni with CO2. Moreover, pore blockage is another issue observed in the coprecipitated catalysts, whereas NiO atoms with crystal sizes of 9
11 nm could be noticed in the impregnated catalysts. It is claimed that polyol catalysts represented higher catalytic activity, while the surfactant-assisted catalysts had lower coke deposition because of the basic nature of the catalyst achieved with this method (Arora and Prasad, 2016). It was also reported that the impregnation technique has several advantages, such as ease of operation and control on metal distribution for the support, but this technique suffers from weak interaction between metal and support. Moreover, Ni-based catalysts prepared with the polyol method showed better catalytic behavior and selectivity in DRB compared to those synthesized with the surfactant-assisted route, whereas the latter method caused lower carbon deposition because of the basic nature of the catalyst (Gao et al., 2018). To study the role of preparation routes, Seol et al. (2018) prepared ZrO2-Al2O3 support with the polymerization-complex route [modified Pechini sol-gel method (PS)], precipitation route [urea hydrolysis (UH)], and physical mixing method (PM) and Ni impregnated over the catalysts. Hydrogen-TPD analysis was carried out to estimate the nickel particle size and distribution on

220

Carbon Dioxide Capture and Conversion

the catalyst surface with H2 desorption spectra below 650°C, and Ni dispersion was found to be higher in the order of PM PS UH (Fig. 8.6). Based on the catalytic tests, Ni/ZrO2-Al2O3 prepared via physical mixing technique showed superior catalytic activity and coke deposition, whereas the Ni supported on ZrO2-Al2O3 prepared via modified Pechini sol-gel and urea hydrolysis techniques exhibited low catalytic activity and stability. However, Ni supported on ZrO2-Al2O3 catalyst prepared with modified Pechini sol-gel technique had a higher resistance for coke deposition. The difference in the catalytic activity is attributed to the variation in the preparation technique that affected the CO2 separation in the DRM (Seol et al., 2018). The impregnation technique is the most common technique for making metal-supported catalysts. Although it is challenging to obtain a narrow particle size distribution, it is possible to prepare small metal particles through this method. Comparing the preparation methods, the coimpregnation method can provide a stronger interaction between metals and supports compared to sequential impregnation. Furthermore, synthesizing

Figure 8.6 Hydrogen-TPD profiles for Ni supported on Al2O3-ZrO2 using different preparation routes (reduced at 900°C for 3 h). Journal of the Taiwan Institute of Chemical Engineers




Dry reforming of methane and biogas to produce syngas

221

the catalysts via plasma treatment can disperse nickel more than the impregnation technique (Usman et al., 2015). It was also found that the surface properties of the catalyst support have a significant impact on the particle size and structure of the metal particles in the impregnation method. Thus, it is challenging to regulate the metal concentrations on the bimetallic catalysts with narrow size distributions, with controlled composition in the microemulsion route owing to the specific structure of this technique. Besides, it was claimed that the microemulsion technique could provide a strong interaction between the active metal and catalyst support. As a result, this technique led to the nanometer range of the particle size, consistent chemical composition, and narrow size distribution, making them suitable catalyst precursors (Shiraz et al., 2016). One of the challenges in the supported catalysts, especially Ni-loaded catalysts, is the sintering of active species causing inactive carbon formation. Controlling the particle size of nickel via different catalyst preparation techniques was found to be one of the solutions to overcome this challenge (Dekkar et al., 2020). To accomplish this, Rh/γ-Al2O3 was developed by incipient wetness impregnation (IWI), atomic layer deposition (ALD), and used in DRM. The results illustrated that the catalyst prepared by ALD showed smaller particle size and narrower size distribution than those prepared from the IWI catalysts with the average size distribution of Rh nanoparticles of 1.8 and 4.2 nm for the samples formulated by ALD and IWI, respectively (Fig. 8.7). Moreover, the catalytic tests showed that the ALD catalysts had higher CH4 conversion and stability relative to the catalysts prepared via the IWI technique (Li et al., 2018). Catalysts prepared via different techniques and conditions show a significant variation in their properties and activity. They culminate in changing particle size, dispersion, and the interaction between catalyst components (e.g., supports, modifiers, and active metals). As a result, these remarkably influence the catalytic activity, stability, and resistance to coke formation in dry reforming (Hambali et al., 2020). Furthermore, Hambali et al. (2020) considered the impact of catalyst preparation methods on the catalytic activity of mesostructured fibrous Ni/MFI zeolite (ZSM-5) in DRM. Ni was introduced into the catalyst via physical mixing, wetness impregnation, and double solvent techniques. The catalytic tests illustrated that the wetness impregnation technique had maximum stability and activity assigned to control the surface acidity that hinders inactivation. Rezaei et al. (2008) claimed that the synthesis of ZrO2 nanopowder with

222

Carbon Dioxide Capture and Conversion

Figure 8.7 Rh size distribution by (A) ALD and (B) IWI. ALD, IWI, .

;

Materials

the surfactant-assisted method could significantly increase the BET surface area. Additionally, Ni impregnated on this support exhibited higher stability after 50 h time on stream. Dekkar et al. (2020) considered the effects of microemulsion and impregnation methods on the catalytic activity of Ni on Al2O3 and Ni/SiO2 in DRM. The findings indicated that the catalytic activity depends on the catalyst support properties and preparation technique. The catalytic characterization showed that the dispersion of Ni on Al2O3 and SiO2 support was higher in the microemulsion technique compared to impregnation. The single phase of NiO was detected for the catalyst prepared by impregnation technique than microemulsion, representing high dispersion of NiO. Mesostructured fibrous zeolite support was prepared by a microemulsion method and Ni was loaded via wet impregnation, double solvent, and physical mixing routes and was used in DRM. The results indicated that the impregnated catalysts had the highest catalytic activity compared to the two other catalysts because of the lower degree of surface acidity and higher Ni dispersion, preventing the catalyst deactivation. Furthermore, prepared Ni supported catalyst on alumina via wet impregnation and solution combustion synthesis (SCS) techniques noticed higher stability without any decline in conversions during 30 h on stream (Hambali et al., 2020). Ali et al. (2020) investigated Ni-based catalysts on the alumina support and investigated in DRM. The findings confirmed that NiO and NiAl2O4 spinel were formed in the SCS route, whereas,

Dry reforming of methane and biogas to produce syngas

223

NiO was detected in the impregnated catalyst. The NiAl2O4 spinel had a higher contribution for better catalytic performance (Ali et al., 2020). Rezaei and Alavi (2019) prepared MgAl2O4-promoted support with CeO2, ZrO2, and La2O3 promoters via sol-gel methods. The results indicated that the sol-gel technique is an effective method to prepare powders with high surface area and porosity, leading to higher Ni dispersion and reactant conversions in dry reforming. Besides, calcination temperature could play an essential role in the catalytic activity during dry reforming reactions. Ni/CeO2-Al2O3 catalysts were prepared by sol-gel and impregnation techniques and used in DRM. The results illustrated well-dispersed Ni particles on the support with the sol-gel method, resulting in improved catalytic activity relative to the impregnation technique (Aghamohammadi et al., 2017). Marinho et al. (2020) assessed the consequence of the preparation method for Ni catalysts. Ni was implanted in CeO2 (Ni@CeO2) and CeZrO2 (Ni@CeZrO2) compared with impregnated Ni/CeO2 in DRM. The results indicated that Ni/CeO2 had a large Ni particle size (around 30 nm), while Ni-implanted catalysts had a reduced metal particle size for Ni@CeO2 (13 nm) and Ni@CeZrO2 (6 nm), respectively. Tested catalysts showed an identical catalytic activity, while coke deposition analysis detected a lower amount of filament carbon deposition for Ni@CeO2 compared to Ni/CeO2. Ni@CeZrO2 catalyst evidenced no carbon deposition in this reaction as well (Fig. 8.8). These observations were assigned to smaller Ni particle size and stronger interaction in embedded catalysts. Rosset et al. (2020) considered the effect of washing steps in the coprecipitation method to evaluate the catalytic activity of Ni on Al2O3 in DRB. The BET results of the fresh catalysts disclosed that the unwashed samples (calcined and uncalcined) had the smallest surface area. On the other hand, the washed catalyst achieved a higher surface area, which can be assigned to the development of the hydrotalcite. Moreover, it was found that the calcined and washed catalysts had more acidic sites, while the calcined unwashed catalysts had a higher quantity and strength of basic sites because of the presence of potassium in the unwashed catalyst. The activity tests demonstrated that the calcined catalysts (washed and unwashed) had higher activity compared to uncalcined ones. Additionally, both unwashed samples displayed a lower amount of carbon deposition in DRB, which can be ascribed to a higher basic property of these catalysts. In summary, it was understood that the catalysts prepared by ALD and microemulsion methods showed better catalytic performance

224

Carbon Dioxide Capture and Conversion

Figure 8.8 Scanning electron microscopy images for spent catalysts after dry reforming of methane at 800°C for 24 h of time on stream.

Applied Catalysis B: Environmental

owing to smaller metal particle size, higher stability relative to conventional routes such as impregnation, precipitation, and better metal dispersion.

8.6 Effects of process conditions Dry reforming process conditions such as reaction and calcination temperatures, pressure, space velocity, and a molar ratio of the reactants are a few important process parameters that show a significant impact on the conversion and yield of DRM. Among all the process parameters, the reaction temperature plays a significant role in carbon formation on the catalysts. Dry reforming processes need higher temperatures because of the endothermic nature of these reactions to produce higher syngas.

Dry reforming of methane and biogas to produce syngas

225

A higher temperature i.e., above 850°C is required to achieve high conversion and to limit coke formation (Alipour et al., 2014a,b). It has been reported that carbon formation incredibly declines along with a temperature rise. It is reported that at 600°C, the amount of formed carbon is much higher than what is formed at 750°C, while another light hydrocarbon dry reforming (except methane) carried out at lower temperature makes them attractive for DRM (Yan et al., 2016; Arvaneh et al., 2019). Khavarian et al. (2015) investigated the effects of the reaction temperature on the catalytic activity of multiwalled carbon nanotubes (MWCNTs) based on nanocomposite catalysts in DRM. It was noticed that the highest CH4 and CO2 conversions and H2/CO ratio were obtained at temperatures more than 800°C because of the endothermic nature of DRM and mild occurrence of RWGS reaction at 800°C. Furthermore, the unreduced catalyst had higher catalytic activity compared to the reduced catalyst. This may be assigned to the presence of disordered carbon in the unreduced catalyst culminating in the reverse methane decomposition reaction. Calcination temperature could considerably affect the catalytic behavior because of its impact on the active metal particle size and the textural properties of the catalysts. Gao et al. (2018) reported that the surface area of Ni/Al2O3 decreased as the calcination temperature increased from 300°C to 750°C. In addition, larger Ni particles were formed by increasing the calcination temperature. As there is no fixed calcination temperature for catalysts, depending on the active metals and supports, an appropriate calcination temperature should be examined based on the metal deposited on the surface of the catalyst (Gao et al., 2018). Ni supported on Al2O3 catalysts with MgO, CaO, and BaO were synthesized with an impregnation technique, and the catalysts were calcined at 500°C and 700°C. Ghods et al. (2016) and Alipour et al. (2014b) showed that the prepared catalysts at a calcination temperature of 700°C had higher catalytic activity compared to those calcined at 500°C, which is because of the availability of the NiO species and better crystallinity of the catalysts prepared at higher calcination temperature. The study of the pressure effect has shown that CH4 and CO2 conversion and coke deposition results in decreased methane decomposition with increasing pressure. However, the Boudouard reaction is favorable at higher pressure (Arora and Prasad, 2016). Navarro-Puyuelo et al. (2019) cofed the oxygen and increased the reaction temperature, which can affect the quantity of carbon deposition

226

Carbon Dioxide Capture and Conversion

on the catalyst. Adding oxygen to the feed not only decreased the deposited coke but also improved the H2/CO ratio toward 1, which is expected at the equilibrium. Further, the reducibility of the calcined catalyst also had an essential role in syngas production. Investigations by Usman et al. (2015) and Gao et al. (2018) indicated that carbon deposited on the Ni/La2O3
CeO2 catalyst was higher when the catalyst was reduced at 450°C compared to 750°C in DRB because of balance between the degree of Ni reduction and metal-support interaction. It is worth noting that mixed reducing agents like H2-N2 and H2-Ar could lead to better reducibility compared to pure H2. This is attributed to better Ni dispersion in the mixed reducing agent (Usman et al., 2015; Gao et al., 2018). It has been revealed that the NiO supported on Al2O3 reduced at 800°C for 4 h and nickel had a strong attraction toward CaO and CaH bond cleavage (Chaudhary et al., 2020). Al-Fatesh et al. (2019) investigated the effects of pretreatment and calcination temperature in the catalytic activity of Ni/Al2O3-ZrO2, Co/Al2O3-ZrO2, and Ni-Co/Al2O3-ZrO2 bimetallic catalysts in DRM. It was observed that the pretreatment (in-situ and ex-situ reduction) improved the catalyst performance and bimetallic catalysts performed better compared to the monometallic because of more available active sites. Furthermore, high calcination temperature accelerates sintering and reduction of surface area, and thus particle growth negatively influences the stability of the catalyst. A similar conclusion was made by Wang et al. (2017) in which crystallinity was improved by increasing the calcination temperature, resulting in increased particle size and declined reducibility. In addition, adding oxygen or steam to the feed can remarkably decline carbon deposition, which results in improved stability (Sun et al., 2020). The effects of reduction temperature in the catalytic activity of NiMo/Al2O3 were studied in DRM. Outcomes of the dry reforming showed better catalytic activity for the catalyst reduced at 600°C and 700°C compared to those reduced at 900°C because of the formation of Ni0 phase at lower reduction temperature and MoNi4 phase at 900°C (Yao et al., 2017). It has been disclosed that conversion of reactants decreased by increasing Gas Hourly Space Velocity (GHSV) because of shorter contact time between the reactants with active sites on the catalyst surface (Alipour et al., 2014c; Meshkani et al., 2014). Furthermore, the effects of feed ratio on the conversion of reactants in dry reforming have been investigated. The results displayed that CH4 conversion decreased by increasing the

Dry reforming of methane and biogas to produce syngas

227

CH4/CO2 ratio, while CO2 conversion increased in DRM. H2/CO ratio also increased with increasing CH4/CO2 ratio owing to reverse water
gas shift reaction that occurred in the lower ratio of CH4/CO2 (Alipour et al., 2014c). Various sources of biogas were evaluated for dry reforming (landfill waste CH4/CO2 1.25, sewage waste CH4/CO2 1.5, and organic waste CH4/CO2 1.85). The results indicated that the landfill waste had higher CH4 conversion at a higher temperature, while CO2 conversion was the lowest for biogas, demonstrating the effects of feed ratio in the conversions (Saché et al., 2019). Chen et al. (2017) examined the effects of O2 on the conversion of CH4 and CO2, carbon deposition, and sintering for Ni/SiO2 catalysts in DRB. It was found that a reasonable quantity of oxygen ( 5%) improved CH4, conversion, and a decrease in CO2 conversion was noticed by adding 5% O2. It was further noted that CH4 conversion was almost identical or higher than CO2 conversion in the presence of O2. In addition, no reduction was observed in the CH4 and CO2 conversions after 15 h on the stream, while declined conversion was noticed without O2. As oxygen is a strong oxidant, the results illustrated that the amount of deposited coke was reduced because of improved carbon activity in the presence of O2 (Nematollahi et al., 2012; Chen et al., 2017). In summary, calcination and reduction temperatures should be appropriate to such an extent that the metal particles do not sinter at high temperatures and low temperatures do not prevent metal-metal oxide formation.

8.7 Role of precursor To enhance the surface area of the catalyst, mineral-type precursors, such as perovskite, spinel, and pyrochlore are proposed by Singh et al. (2019). Among all the precursors, perovskites were widely used in catalyst preparations because of the high dispersion of active metals, thermal resistance, and low cost (Chein and Fung, 2019). Spinels are the combination of mixed metal oxides with the typical formula AB2O4, where A is divalent and B is trivalent metal cations, respectively; these have been widely used in supports. The interesting behavior of spinels is owing to the presence of two catalytically active metal cations homogeneously dispersed on the surface of the catalyst. MgAl2O4 is one of the most attractive spinels used as a support in dry reforming. Furthermore, Ni/MgAl2O4 catalysts showed higher catalytic activity owing to the strong interaction among

228

Carbon Dioxide Capture and Conversion

Ni and catalyst support material in dry reforming processes compared to Ni/ ZrO2 and Ni/ Al2O3 catalysts (Nair and Kaliaguine, 2016). Kühl et al. (2017) suggested LaNiO3 perovskite as a suitable catalyst (Ni/La2O3) in DRM at high temperatures. The same results have been reported by Gao et al. (2019) that Ni/La2O3 catalyst showed higher catalytic activity and low coke deposition when LaNiO3 perovskite was used as precursor, which resulted in better Ni dispersion and strong interaction between Ni and the support. The obtained catalyst from hydrotalcite [layered double hydroxide (LDHs)] precursor showed good catalytic activity and stability in dry reforming. The general formula for this type of precursor is [MII 1_xMIII x(OH)2]x (An-)x/n y H2O, where MIII and MII are trivalent and divalent metal cations, respectively, where An- is the anion of compensation, y is the degree of hydration, and x is the mole fraction of the trivalent cation. These materials could form a solid oxide with basic nature after calcination, showing high surface area, small crystal size, and high dispersion, which are good candidates for heterogeneous catalysts. Moreover, LDHs samples could be synthesized through various routes such as coprecipitation, sol-gel, and ion exchange (Tanios et al., 2017).

8.8 Conclusions Dry reforming of methane has attracted attention recently because of the abundance of natural gas. Further, dry reforming of biogas (mixture of methane and carbon dioxide) has gained tremendous attention owing to the consumption of greenhouse gases and production of syngas, which is a potential feedstock for the Fischer-Tropsch process. Upon critical review of the catalyst synthesis techniques, loading different active metals on the catalyst support, mono vs bimetallic catalysts, the effects of modifiers, process conditions, and role of precursors, it was understood that the primary challenge with DRM catalysts are carbon deposition and sintering, which lead to the reduced catalytic activity. During DRM, catalytic activity and resistance to deactivation are impacted by the aforementioned factors. Proper understanding and providing a guideline for synthesizing appropriate catalysts are important for the commercial production of the catalysts for industrial applications. In addition to the strong metal-support interaction, active metal particle size, metal dispersion, and type of support affect the DR catalyst stability and activity. Bimetallic catalysts are more

Dry reforming of methane and biogas to produce syngas

229

active with high metal dispersion with a low particle size, which is the requirement for the DRM process. Along with dispersion and particle size, surface area, active metal reducibility, basicity, porosity, and oxygen storage capacity showed a significant impact on the DRM related to the nature of the support. Thus, the addition of a low amount of alkaline and alkaline earth metals such as MgO, CaO, K2O, and BaO can remarkably reduce coke formation because these metals increase the basicity of the catalysts and CO2 adsorption and inhibit CO decomposition. Further, the role of support that causes Ni dispersion and metal
support interaction was investigated. Al2O3 and MgO have been widely used by researchers in dry reforming, showing higher catalytic activity compared to other supports. In addition, using CNTs as support and core-shell type catalysts are highly recommended because of low carbon formation because of encapsulated Ni particles and less surface area to form coke. In the case of the preparation method, the results demonstrated that the impregnation technique was found to be the most common method to synthesize catalysts, whereas microemulsion is a better route to produce catalysts with a higher surface area. The preparation method and precursor play significant roles in the Ni dispersion and interaction between supports and active metal. Using perovskites as a precursor in the catalyst preparation could notably increase the interaction between Ni and the supports as well as boost Ni dispersion, resulting in improved conversion and lower carbon deposition. As the dry reforming is an endothermic process, it was carried out at higher temperatures ( 800°C) with better conversion and lower coke deposition; therefore, adding O2 could remarkably decrease the amount of coke deposition. Dry reforming of biogas into syngas has been the focus because of the rapid increase in biogas production around the world. It is highly recommended to use the real sources of biogas for this process to understand the real challenges in the catalyst and reactor designs and move forward for better catalyst production with less coke deposition, which is the main drawback of dry reforming catalysts on the industrial scale. Ni and Cobased catalysts with CNTs and core/yolk shell-type catalysts have not been studied much for biogas dry reforming. Based on the higher surface area and support properties of CNTs and core/yolk shell-type catalysts in dry reforming of methane, it is expected that these catalysts will show high catalytic activity in biogas dry reforming. Also, the sintering and coke resistance of the catalysts should be favored by employing and comparing the alkaline earth promoters in these catalysts.

230

Carbon Dioxide Capture and Conversion

It is noteworthy to mention that particle size and surface area play an essential role in dispersion, higher surface area, and smaller particle size culminating in a better catalytic performance with the significant resistance toward coke formation. Further, catalysts with small particle sizes and a high surface area should be synthesized to improve the lifetime of the catalysts. Comparing CNT-supported catalysts with the core-shell type and conventionally prepared catalysts, such as impregnation and precipitation using biogas, could significantly result in the proper catalyst design for commercial applications. Various sources of biogas should be investigated to establish the mature commercialization of the process using catalyst components with increased catalyst stability and activity.

Acknowledgments The financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Research Chairs (CRC) program is acknowledged.

References Abidin, S.Z., Ideris, A., Ainirazali, N., Ismail, M., 2020. A short review on production of syngas via glycerol dry reforming. In: Inamuddin, A.M.A., Lichtfouse, E. (Eds.), Conversion of Carbon Dioxide into Hydrocarbons Vol. 2 Technology. Environmental Chemistry for a Sustainable World 41. Springer, pp. 185
197. Aghamohammadi, S., Haghighi, M., Maleki, M., Rahemi, N., 2017. Sequential impregnation vs. sol-gel synthesized Ni/Al2O3-CeO2 nanocatalyst for dry reforming of methane: effect of synthesis method and support promotion. Molecular Catalysis 431, 39
48. Akbari, E., Alavi, S.M., Rezaei, M., 2017. Synthesis gas production over highly active and stable nanostructured Ni/MgO/Al2O3 catalysts in dry reforming of methane: effects of Ni contents. Fuel 194, 171
179. Al-Fatesh, A.S., Dahrieh, J.K., Atia, H., Armbruster, U., Ibrahim, A., Khan, W., et al., 2019. Effect of pre-treatment and calcination temperature on Al2O3-ZrO2 supported Ni-Co catalysts for dry reforming of methane. International Journal of Hydrogen Energy 44, 21546
21558. Ali, S., Khader, M., Almarri, M., Abdelmoneim, A.G., 2020. Ni-based nano-catalysts for the dry reforming of methane. Catalysis Today 343, 26
37. Alipour, Z., Rezaei, M., Meshkani, F., 2014a. Effect of Ni loadings on the activity and coke formation of MgO-modified Ni/Al2O3 nanocatalyst in dry reforming of methane. Journal of Energy Chemistry 23, 633
638. Alipour, Z., Rezaei, M., Meshkani, F., 2014b. Effects of support modifiers on the catalytic performance of Ni/Al2O3 catalyst in CO2 reforming of methane. Fuel 129, 197
203. Alipour, Z., Rezaei, M., Meshkani, F., 2014c. Effect of alkaline earth promoters (MgO, CaO, and BaO) on the activity and coke formation of Ni catalysts supported on

Dry reforming of methane and biogas to produce syngas

231

nanocrystalline Al2O3 in dry reforming of methane. Journal of Industrial and Engineering Chemistry 20, 2858
2863. Alipour, Z., Mehskani, F., Rezaei, M., 2015. Effect of K2O on the catalytic performance of Ni catalysts supported on nanocrystalline Al2O3 in CO2 reforming of methane. Iranian Journal of Hydrogen & Fuel Cell 4, 215
226. Aouad, S., Labaki, M., Ojala, S., Seelam, P., 2018. A review on the dry reforming processes for hydrogen production: catalytic hydrogen production. Frontiers in Ceramic Science 2, 60
128. Arora, S., Prasad, R., 2016. An overview on dry reforming of methane:strategies to reduce carbonaceous deactivation of catalysts. RSC Advances 6, 108668
108688. Arvaneh, R., Azizzadeh, F.A., Bazyari, A., Alavi, S.M., Jokar, J.F., 2019. Effects of Ce, La, Cu, and Fe promoters on Ni/MgAl2O4 catalysts in steam reforming of propane. Korean Journal of Chemical Engineering 36, 1033
1041. Ashik, U.P.M., Viswan, A., Kudo, S., Hayashi, J., 2018. Chapter 3
Nanomaterials as Catalysts. In: Bhagyaraj, S.M., Oluwafemi, O.S., Kalarikkal, N., Thomas, S. (Eds.), Micro and Nano Technologies, Applications of Nanomaterials. Woodhead Publishing, pp. 45
82. Aziz, M.A., Setiabudi, H.D., Teh, L.P., Annuar, N.H., Jalil, A.A., 2019. A review of heterogeneous catalysts for syngas production via dry reforming. Journal of the Taiwan Institute of Chemical Engineers 101, 139
158. Bac, S., Keskin, S., Avci, A., 2019. Recent advances in sustainable syngas production by catalytic CO2 reforming of ethanol and glycerol. Sustainable Energy & Fuels 3, 1029
1047. Bian, Z., Das, S., Wai, M.H., Hongmanorom, P., Kawi, S., 2017. A review on bimetallic nickel-based catalysts for CO2 reforming of methane. Chemphyschem: A European Journal of Chemical Physics and Physical Chemistry 18, 3117
3134. Calgaro, C., Lopez, O., 2019. Biogas dry reforming for hydrogen production over Ni-MAl catalysts (M Mg, Li, Ca, La, Cu, Co, Zn). International Journal of Hydrogen Energy 44, 17750
17766. Carvalho, D.C., Souza, H.S.A., Filho, J.M., Oliveira, A.C., Campos, A., Milet, E.R.C., Sousa, F.F., Padron-Hernandeze, E., Oliveira, A.C., 2014. A study on the modification of mesoporous mixed oxides supports for dry reforming of methane by Pt or Ru. Applied Catalysis A: General 473, 132
145. Chaudhary, P.K., Koshta, N., Deo, G., 2020. Effect of O2 and temperature on the catalytic performance of Ni/Al2O3 and Ni/MgAl2O4 for the dry reforming of methane (DRM). International Journal of Hydrogen Energy 45, 4490
4500. Chein, R.Y., Fung, W., 2019. Syngas production via dry reforming of methane over CeO2 modified Ni/Al2O3 catalysts. International Journal of Hydrogen Energy 44, 14303
14315. Chen, X., Jiang, J., Li, K., Tian, S., Yan, F., 2017. Energy-efficient biogas reforming process to produce syngas: the enhanced methane conversion by O2. Applied Energy 185, 687
697. Dekkar, S., Tezkratt, S., Sellam, D., Ikkour, K., Parkhomenko, K., Martinez-Martin, A., et al., 2020. Dry reforming of methane over Ni
Al2O3 and Ni
SiO2 catalysts: role of preparation methods. Catalysis Letters 150, 2180
2199. Djinovi´c, P., Batista, J., Pintar, A., 2012. Efficient catalytic abatement of greenhouse gases: Methane reforming with CO2 using a novel and thermally stable Rh
CeO2 catalyst. International Journal of Hydrogen Energy 37, 2699
2707. Fu, X., Yu, H., Peng, F., Wang, H., Qian, Y., 2007. Facile preparation of RuO2/CNT catalyst by a homogenous oxidation precipitation method and its catalytic performance. Applied Catalysis A: General 321, 190
197. Gao, Y., Jiang, J., Meng, Y., Yan, F., Aihemaiti, A., 2018. A review of recent developments in hydrogen production via biogas dry reforming. Energy Conversion and Management 171, 133
155.

232

Carbon Dioxide Capture and Conversion

Gao, R., Song, M., Wei, Y., Yu, L., Meng, F., 2019. CO2 reforming of methane over Ni/carbon fibers-La2O3 catalyst: effects of ultrasound-assisted method and La2O3 properties and activity. Waste and Biomass Valorization 10, 3897
3905. Gao, Y., Aihemaiti, A., Jiang, J., Meng, Y., Ju, T., Han, S., et al., 2020. Inspection over carbon deposition features of various nickel catalysts during simulated biogas dry reforming. Journal of Cleaner Production 260, 120944. Ghelamallah, M., Granger, P., 2014. Supported-induced effect on the catalytic properties of Rh and Pt-Rh particles deposited on La2O3 and mixed α-Al2O3-La2O3 in the dry reforming of methane. Applied Catalysis A: General 485, 172
180. Ghods, B., Meshkani, F., Rezaei, M., 2016. Effects of alkaline earth promoters on the catalytic performance of the nickel catalysts supported on high surface area mesoporous magnesium silicate in dry reforming reaction. International Journal of Hydrogen Energy 41, 22913
22921. Ha, Q., Armbruster, U., Kreyenschulte, C., Atia, H., Lund, H., Vuong, H., et al., 2019. Stabilization of low nickel content catalysts with lanthanum and by citric acid assisted preparation to suppress deactivation in dry reforming of methane. Catalysis Today 334, 203
214. Hambali, H.U., Jalil, A.A., Abdulrasheed, A.A., Siang, T.J., Vo, D.V.N., 2020. Enhanced dry reforming of methane over mesostructured fibrous Ni/MFI zeolite: influence of preparation methods. Journal of the Energy Institute 93, 1535
1543. Han, B., Wang, F., Zhang, L., Wang, Y., Fan, W., Xu, L., Yu, H., Li, Z., 2020. Syngas production from methane steam reforming and dry reforming reactions over sinteringresistant Ni@SiO2 catalyst. Research on Chemical Intermediates 46, 1735
1748. Hou, T., Yuan, L., Ye, T., Gong, L., Tu, J., Yamamoto, M., et al., 2009. Hydrogen production by low-temperature reforming of organic compounds in bio-oil over a CNTpromoting Ni catalyst. International Journal of Hydrogen Energy 34, 9095
9107. Jang, W.J., Shim, J., Kim, H., Yoo, S., Roh, H., 2019. A review on dry reforming of methane in aspect of catalytic properties. Catalysis Today 324, 15
26. Jawad, A., Rezaei, F., Rownaghi, A., 2019. Highly efficient Pt/Mo-Fe/Ni-based Al2O3CeO2 catalysts for dry reforming of methane. Catalysis Today 350, 80
90. Kamieniak, J., Bernalte, E., Doyle, A.M., Kelly, P., Banks, C.E., 2017. Can ultrasound or pH influence Pd distribution on the surface of HAP to improve its catalytic properties in the dry reforming of methane? Catalysis Letters 147, 2200
2208. Kang, M., Kim, H.W., Shim, I.W., Kwak, H.Y., 2011. Catalytic test of supported Ni catalysts with core/shell structure for dry reforming of methane. Fuel Processing Technology 92, 1236
1243. Khavarian, M., Chai, S., Mohamed, A., 2015. The effects of process parameters on carbon dioxide reforming of methane over Co
Mo
MgO/MWCNTs nanocomposite catalysts. Fuel 158, 129
138. Kühl, S., Düdder, H., Girgsdies, F., Kähler, K., Muhler, M., Behrens, M., 2017. Perovskites as precursors for Ni/La2O3 catalysts in the dry reforming of methane: synthesis by constant pH Co-precipitation, reduction mechanism and effect of Rudoping. Journal of Inorganic and General Chemistry 643, 1088
1095. Li, Y., Jiang, J., Zhu, C., Li, L., Li, Q., Ding, Y., et al., 2018. The enhanced catalytic performance and stability of Rh/-Al2O3 catalyst synthesized by atomic layerdeposition (ALD) for methane dry reforming. Materials 11, 172. Li, Z., Wang, Z., Kawi, S., 2019a. Sintering and coke resistant core/yolk shell catalyst for hydrocarbon reforming. ChemCatChem 11, 202
224. Li, B., Luo, Y., Yuan, X., Wang, X., 2019b. Catalytic performance of iron-promoted nickel-based ordered mesoporous alumina FeNiAl catalysts in dry reforming of methane. Fuel Processing Technology 193, 348
360. Li, L., Zhou, L., Ould-Chikh, S., Anjum, D.H., Kanoun, M.B., Scaranto, J., Hedhili, M. N., Khalid, S., Laveille, P.V., D’Souza, L., Clo, A., Basset, J., 2015. Controlled surface

Dry reforming of methane and biogas to produce syngas

233

segregation leads to efficient coke-resistant nickel/platinum bimetallic catalysts for the dry reforming of methane. ChemCatChem 7, 819
829. Macario, A., Frontera, P., Candamano, S., Crea, F., De Luca, P., Antonucci, P.L., 2019. Nanostructured catalysts for dry-reforming of methane. Journal of Nanoscience and Nanotechnology 19, 3135
3147. Marinho, A., Rabelo-Neto, R.C., Epron, F., Bio, N., Toniolo, F., Noronha, F., 2020. Embedded Ni nanoparticles in CeZrO2 as stable catalyst for dry reforming of methane. Applied Catalysis B: Environmental 268, 118387. Meshkani, F., Rezaei, M., Andache, M., 2014. Investigation of the catalytic performance of Ni/MgO catalysts in partial oxidation, dry reforming and combined reforming of methane. Journal of Industrial and Engineering Chemistry 20, 1251
1260. Mirzaei, F., Rezaei, M., Meshkani, F., 2014. Coprecipitated Ni-Co bimetallic nanocatalysts for methane dry reforming. Chemical Engineering Technology 37, 973
978. Mirzaei, F., Rezaei, M., Meshkani, F., 2015. Carbon dioxide reforming of methane for syngas production over Co
MgO mixed oxide nanocatalysts. Journal of Industrial and Engineering Chemistry 21, 662
667. Nair, M.M., Kaliaguine, S., 2016. Structured catalysts for dry reforming of methane. New Journal of Chemistry 40, 4049
4060. Nanda, S., Reddy, S.N., Mitra, S.K., Kozinski, J.A., 2016. The progressive routes for carbon capture and sequestration. Energy Science & Engineering 4, 99
122. Navarro-Puyuelo, A., Reyero, I., Moral, A., Bimbela, F., Bañares, M.A., Gandía, L.M., 2019. Effect of oxygen addition, reaction temperature and thermal treatments on syngas production from biogas combined reforming using Rh/alumina catalysts. Journal of Industrial and Engineering Chemistry 80, 217
226. Nematollahi, B., Rezae, M., Khajenoori, M., 2011. Combined dry reforming and partial oxidation of methane to synthesis gas on noble metal catalysts. International Journal of Hydrogen Energy 36, 2969
2978. Nematollahi, B., Rezaei, M., Nemati, E., Khajenoori, M., 2012. Thermodynamic analysis of combined reforming process using Gibbs energy minimization method: in view of solid carbon formation. Journal of Natural Gas Chemistry 21, 694
702. Nguyen, T.D., Tran, T.V., Singh, S., Phuong, P.T.T., Bach, L.G., Nanda, S., et al., 2020. Conversion of carbon dioxide into formaldehyde. In: Inamuddin, A.M.A., Lichtfouse, E. (Eds.), Conversion of Carbon Dioxide into Hydrocarbons. Vol. 2 Technology. Springer Nature, Singapore, pp. 159
183. Pakhare, D., Shaw, C., Haynes, D., Shekhawat, D., Spivey, J., 2013. Effect of reaction temperature on activity of Pt- and Ru-substituted lanthanum zirconate pyrochlores (La 2 Zr 2 O 7 ) for dry (CO 2 ) reforming of methane (DRM). Journal of CO2 Utilization 1, 37
42. Pakhare, D., Spivey, J., 2014. A review of dry (CO2) reforming of methane over noble metal catalysts. Chemical Society Reviews 43, 7813
7837. Ramezani, Y., Meshkani, F., Rezaei, M., 2018a. Preparation and evaluation of mesoporous nickel and manganese bimetallic nanocatalysts in methane dry reforming process for syngas production. Journal of Chemical Science 130, 11. Ramezani, Y.Y., Meshkani, F., Rezaei, M., 2018b. Promotional effect of Mg in trimetallic nickel manganese-nanocrystalline catalysts in CO2 reforming of methane. International Journal of Hydrogen Energy 43, 22347
22356. Rezaei, M., Alavi, S.M., 2019. Dry reforming over mesoporous nanocrystalline 5% Ni/ M-MgAl2O4 (M: CeO2, ZrO2, La2O3) catalysts. International Journal of Hydrogen Energy 44, 16516
16525. Rezaei, M., Alavi, S.M., Sahebdelfar, S., Bai, P., Liu, X., Yan, Z., 2008. CO2 reforming of CH4 over nanocrystalline zirconia-supported nickel catalysts. Applied Catalysis B: Environmental 77, 346
354.

234

Carbon Dioxide Capture and Conversion

Rosha, P., Mohapatra, S., Mahla, S., Dhir, A., 2019a. Catalytic reforming of synthetic biogas for hydrogen enrichment over Ni supported on ZnO-CeO2 mixed catalyst. Biomass and Bioenergy 125, 70
78. Rosha, p, Mohapatra, S., Mahla, S., Dhir, A., 2019b. Hydrogen enrichment of biogas via dry and autothermal-dry reforming with pure nickel (Ni) nanoparticle. Energy 172, 733
739. Rosset, M., Féris, L., Perez-Lopez, O., 2020. Biogas dry reforming over Ni-Al catalyst: suppression of carbon deposition by catalyst preparation and activation. International Journal of Hydrogen Energy 45, 6549
6562. Saché, E., Jonhson, S., Pastor-Pérez, L., Horri, B., Reina, T., 2019. Biogas upgrading via dry reforming over a Ni-Sn/CeO2-Al2O3 catalyst: influence of the biogas source. Energies 12, 1007. Seol, S., Su, N., Hoon, G., In, Tae, S., Young, L., et al., 2018. Dry reforming of methane over Ni/ZrO2-Al2O3 catalysts: effect of preparation methods. Journal of the Taiwan Institute of Chemical Engineers 90, 25
32. Shiraz, M., Rezaei, M., Meshkani, F., 2016. Preparation of nanocrystalline Ni/Al2O3 catalysts with the microemulsion method for dry reforming of methane. The Canadian Journal of Chemical Engineering 94, 1177
1183. Singh, S., Kumar, R., Setiabudi, H.D., Nanda, S., Vo, D.V.N., 2018. Advanced synthesis strategies of mesoporous SBA-15 supported catalysts for catalytic reforming applications: a state-of-the-art review. Applied Catalysis A: General 559, 57
74. Singh, R., Dhir, A., Mohapatra, S., Mahla, S., 2019. Dry reforming of methane using various catalysts in the process: review. Biomass Conversion and Biorefinery 10, 567
587. Singha, R.K., Yadav, A., Shukla, A., Kumar, M., Bal, R., 2017. Low temperature dry reforming of methane over Pd-CeO2 nanocatalyst. Catalysis Communications 92, 19
22. Sudhakaran, M.S.P., Sultana, L., Hossain, M.M., Pawlat, J., Diatczyk, J., Brüser, V., et al., 2018. Iron
ceria spinel (FeCe2O4) catalyst for dry reforming of propane to inhibit carbon formation. Journal of Industrial and Engineering Chemistry 61, 142
151. Sun, Y., Zhang, G., Liu, J., Xu, J., Lv, Y., 2020. Production of syngas via CO2 methane reforming process: effect of cerium and calcium promoters on the performance of Ni-MSC catalysts. International Journal of Hydrogen 45, 640
649. Tanios, C., Bsaibes, S., Gennequin, C., Labaki, M., Cazier, F., Billet, S., et al., 2017. Syngas production by the CO2 reforming of CH4 over Ni-Co-Mg-Al catalysts obtained from hydrotalcite precursors. International Journal of Hydrogen Energy 42, 12818
12828. Turap, Y., Wang, I., Fu, T., Wu, Y., Wang, Y., Wang, W., 2020. Co-Ni alloy supported on CeO2 as a bimetallic catalyst for dry reforming of methane. International Journal of Hydrogen Energy 45, 6538
6548. Usman, M., Daud, W., Abbas, H., 2015. Dry reforming of methane: influence of process parameters—A review. Renewable and Sustainable Energy Reviews 45, 710
744. Wang, H., Zhang, J., Dalai, A.K., 2011. Catalyst for production of sythesis gas. University of Saskatchewan, Patent No. US 7,985,710 B2. Wang, H., Miller, J., Shakouri, M., Xi, C., Wu, T., Zhao, H., et al., 2013. XANES and EXAFS studies on metal nanoparticle growth and bimetallic interaction of Ni-based catalysts for CO2 reforming of CH4. Catalysis Today 207, 3
12. Wang, F., Xu, L., Shi, W., 2016. Syngas production from CO2 reforming with methane over core-shell Ni@SiO2 catalysts. Journal of CO2 Utilization 16, 318
327. Wang, Z., Hu, Z., Dong, D., Parkinson, G., Li, C., 2017. Effects of calcination temperature of electrospun fibrous Ni/Al2O3 catalysts on the dry reforming of methane. Fuel Processing Technology 155, 246
251.

Dry reforming of methane and biogas to produce syngas

235

Wysocka, I., Hupka, J., Rogala, A., 2019. Catalytic activity of nickel and ruthenium
nickel catalysts supported on SiO2, ZrO2, Al2O3, and MgAl2O4 in a dry reforming process. Catalysts 9, 540. Xie, Z., Yan, B., Lee, J., Wu, Q., Li, X., Zhao, B., et al., 2019. Effects of oxide supports on the CO2 reforming of ethane over Pt-Ni bimetallic catalysts. Applied Catalysis B: Environmental 245, 376
388. Yadav, A.K., Vaidya, P.D., 2019. Renewable hydrogen production by steam reforming of butanol over multiwalled carbon nanotube-supported catalysts. International Journal of Hydrogen Energy 44, 30014
30023. Yan, B., Yang, X., Yao, S., Wan, J., Myint, M., Gomez, E., et al., 2016. Dry reforming of ethane and butane with CO2 over PtNi/CeO2 bimetallic catalysts. Catalysis 11, 7283
7292. Yao, L., Galvez, M., Hu, C., Costa, P., 2017. Mo-promoted Ni/Al2O3 catalyst for dry reforming of methane. International Journal of Hyrogen Energy 42, 23500
23507. Yentekakis, I.V., Goula, G., Panagiotopoulou, P., Katsoni, A., Diamadopoulos, E., Mantzavinos, D., Delimitis, A., 2015. Dry reforming of methane: catalytic performance and stability of Ir catalysts supported on γ-Al2O3, Zr0.92Y0.08O2 δ (YSZ) or Ce0.9Gd0.1O2 δ (GDC) supports. Topics in Catalysis 58, 1228
1241. Zhan, Y., Han, J., Bao, Z., Cao, B., Li, Y., Street, J., et al., 2017. Biogas reforming of carbon dioxide to syngas production over Ni-Mg-Al catalystsJ. H Molecular Catalysis 48
258. Zhang, R.J., Xia, G., Wu, M., Nie, H., Li, D., 2015. Effect of support on the performance of Ni-based catalyst in methane dry reforming. Journal of Fuel Chemistry and Technology 43, 1359
1365. Zhang, J., Li, F., 2015. Coke-resistant Ni@SiO2 catalyst for dry reforming of methane. Applied Catalysis B: Environmental 176-177, 513
521. Zhang, T., Liu, Z., Zhu, Y., Liu, Z., Sui, Z., Zhu, K., et al., 2020. Dry reforming of methane on Ni-Fe-MgO catalysts: influence of Fe on carbon-resistant property and kinetics. Applied Catalysis B: Environmental 264, 118497.

CHAPTER 9

Advances in the industrial applications of supercritical carbon dioxide Jude A. Okolie1, Sonil Nanda1, Ajay K. Dalai1 and Janusz A. Kozinski2 1

Department of Chemical and Biological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada Faculty of Engineering, Lakehead University, Thunder Bay, Ontario, Canada

2

9.1 Introduction The world today is surrounded by several environmental issues, including elevating energy demand, pollution, overdependency on petroleum resources, and climate change (Nanda et al., 2013, 2014; Patra et al., 2021; Tcvetkov et al., 2019). To address these challenges, waste-to-energy conversion processes have been the subject of intense research (Sarker et al., 2021; Okolie et al., 2021a). The conversion of waste into energy occurs through different thermochemical (e.g., pyrolysis, liquefaction, and gasification) and biological (e.g., anaerobic digestion and fermentation) conversion processes (Nanda and Berruti, 2021a,b,c). Through the waste-to-energy conversion processes, different sources of energy or energy carriers, including crude oil, hydrogen, and biochars, can be developed (Nanda et al., 2016a; Sarangi and Nanda, 2020; Parakh et al., 2020). However, the waste-to-energy conversion processes such as gasification and liquefaction also produce carbon dioxide (CO2) as a major component of the product gas. Although, adequate CO2 capture technology is integrated into most of the conversion processes to control its atmospheric emissions (Okolie et al., 2021b). CO2 is widely known as a major greenhouse gas, although it is nonflammable, nonreactive under most conditions (Mukherjee et al., 2019). Furthermore, CO2 produced from the combustion of fossil fuels contributes about 76% of the global greenhouse gas emissions (Siqueira et al., 2017). The current CO2 level in the atmosphere is 410 ppm (Lindsey, 2020). The rise in CO2 is seen as a major contributor to climate change and global warming (Nanda et al., 2016b; Nguyen et al., 2020). Carbon Dioxide Capture and Conversion DOI: https://doi.org/10.1016/B978-0-323-85585-3.00008-0

© 2022 Elsevier B.V. All rights reserved.

237

238

Carbon Dioxide Capture and Conversion

Therefore, there is an urgent need to develop technologies that can either capture CO2 from the atmosphere or utilize it in several industrial processes (Singh et al., 2018; Shafiqah et al., 2020). Supercritical fluids refer to fluids with temperatures and pressures beyond their critical values (Reddy et al., 2014a,b). These fluids exist in the supercritical state in which there is no noticeable difference between the liquid and gaseous phases (Rana et al., 2018, 2019, 2020; Okolie et al., 2019, 2020). Supercritical water (SCW) and supercritical CO2 (SCCO2) are the most studied supercritical fluids to be used as a medium for solvent-free chemical processes and in environmental remediation (Nanda et al., 2017; Crabtree et al., 2007). SCCO2 refers to CO2 above its critical temperature and pressure of 31.1°C and 7.38 MPa, respectively (Weibel and Ober, 2003). At ambient temperature, CO2 exhibits gaseous properties in air, or as solid (also known as dry ice) when it is cooled or pressurized. However, under supercritical conditions, the property of CO2 varies between that of a gas and a liquid. SCCO2 shows many unique properties that facilitate its utilization in several industrial applications, including food extractions (Sahena et al., 2009), pharmaceutical applications (Weibel and Ober, 2003), extrusion processes (Chauvet et al., 2017), and upgrading of crude oil and biooil in the energy industry (Reddy et al., 2018; Nanda et al., 2021). This chapter provides an overview of SCCO2, and its unique properties are outlined and compared with other supercritical fluids, including SCW, supercritical ethanol, and supercritical methanol. Additionally, several industrial applications of SCCO2 in the extraction of bioactive compounds, heavy oil upgrading, production of platform chemicals, and energy industries are reviewed and discussed.

9.2 Unique properties of SCCO2 Supercritical fluid refers to fluids whose temperature and pressure are above their critical values, as discussed in Table 9.1. Hence, they exist in the supercritical state and show unique features such as gas- and liquidlike properties that enhance their utilization for several industrial applications. In the case of CO2, at temperature and pressure above 31.1°C and 7.38 MPa, respectively, CO2 exists in the supercritical state. Compared to most compounds, the critical point of CO2 is at a lower temperature and pressure (Table 9.1). Furthermore, CO2 is abundantly available considering its increasing concentration in the atmosphere due to massive

Advances in the industrial applications of supercritical carbon dioxide

239

Table 9.1 Critical properties of some pure components. Component

Critical temperature (°C)

Critical pressure (MPa)

Acetone Carbon dioxide Ethane Ethanol Ethyl acetate Ethylene Methanol n-Hexane Nitrous oxide Propane Water

235.1 31.1 32.3 240.9 250.2 9.4 239.6 234.5 36.6 96.8 374

4.7 7.38 4.87 6.14 3.83 5.04 8.09 3.01 7.26 4.25 22.1

Reproduced with permission from Sahena, F., Zaidul, I.S.M., Jinap, S., Karim, A.A., Abbas, K.A., Norulaini, N.A.N., et al., 2009. Application of supercritical CO2 in lipid extraction
a review. Journal of Food Engineering 95, 240
253.

Figure 9.1 Phase diagram of CO2 with constant density lines (represented by dotted lines).


industrial activities. Therefore, it can be widely used for several industrial applications when compared with other supercritical compounds. Fig. 9.1 shows the pressure versus temperature phase diagram of CO2 with the constant density lines. At a temperature below
60°C, CO2 exists in the solid state (also known as dry ice) regardless of the pressure.

240

Carbon Dioxide Capture and Conversion

When the temperature and pressure exceed 31.1°C and 7.38 MPa, respectively, the phase boundary disappears. The absence of phase boundaries under supercritical conditions led to an improved mass transfer and solvation properties together with low surface tension (Qi et al., 2018). There is also a drastic change in the viscosity and density of CO2 under supercritical conditions. The density of SCCO2 is similar to that of liquid CO2, while its viscosity is almost the same as that of gaseous CO2, and these properties improve its ability to dissolve several organic and inorganic compounds (Nowak and Winter, 2017). In addition to the unique physicochemical properties of SCCO2, its solvent properties can be finetuned through density adjustments to meet specific operating conditions for different chemical processes. Therefore, SCCO2 has been widely used for the selective extraction of various bioactive compounds (Pattnaik et al., 2022). Compared to the conventional solvents, SCCO2 leaves little or no amount of residues behind during extraction (Naik et al., 2010).

9.3 Industrial applications of SCCO2 9.3.1 Extraction of bioactive compounds Bioactive compounds present in functional foods and natural sources are known for their antimicrobial, antibacterial, antifungal, antiviral, antimicrobial, antibacterial, antifungal, antiviral, and antioxidant properties (Pereira and Meireles, 2010; Hans et al., 2021). Bioactive compounds such as phenolics, flavonoids, carotenoids, tocotrienols, amines, omega-3 fatty acids, organic acids, etc., have attracted great interest as a result of their ability to prevent several chronic ailments (Kamiloglu et al., 2021). For example, the phenolic compounds produced from Rosmarinus officinalis showed antitumor activity (Sánchez-Camargo et al., 2014). Another study revealed that perillyl alcohol could be used to prevent the formation and progression of different types of cancer (Serra et al., 2010). Owing to the health benefits of these bioactive compounds, the method in which they can be obtained from functional foods or natural sources is a subject of interest among several researchers. Bioactive compounds can be obtained through several extraction processes (Hans et al., 2021). However, the extract quality is largely dependent on several factors, including the method of extraction, temperature, and extraction time as well as the type of extraction solvent (da Silva et al., 2016). Conventional extraction methods such as maceration and Soxhlet extraction use toxic and expensive solvents, including methanol and

Advances in the industrial applications of supercritical carbon dioxide

241

dichloromethane. Furthermore, the conventional methods are timeconsuming and would require several hours to attain complete extraction of the bioactive compounds (Pereira and Meireles, 2010). On the other hand, supercritical fluid extraction is a rapid, efficient, and environmentally friendly method for recovering bioactive compounds from natural products (Pereira and Meireles, 2010). CO2 is the most used solvent for supercritical fluid extraction for the following reasons: 1. Its low critical temperature is suitable for preserving the structure of the bioactive compounds in the extract (Barbosa et al., 2014). 2. CO2 is a gas at ambient temperature. Therefore, it is easily removed from the system after extraction, thereby producing a solvent-free extract. Table 9.2 compares SCCO2 with conventional solvent extraction. Several studies have evaluated the potential of SCCO2 for the extraction of bioactive compounds from natural sources (Espinosa-Pardo et al., 2014; Pimentel-Moral et al., 2019). Espinosa-Pardo et al. (2014) compared the yields of bioactive compounds obtained from SCCO2 extraction with that of Soxhlet extraction with methanol and petroleum ether solvents. Their results show that SCCO2 produced lower yields when compared to Table 9.2 A comparison between SCCO2 and solvent extraction for the recovery of bioactive compounds. Supercritical CO2

Solvent extraction

• Extracts contain high purity and completely free of solvents

• A solvent is left behind in the extracts • The residual solvent is dependent on the type and nature of the solvent used • Inorganic salts and heavy metal contents are unavoidable • Their presence is dependent on the type of solvent used, the recycling technique, and the materials used to construct the contact parts of the system • Could extract polar and nonpolar compounds • Solvent separation and removal could require additional processing unit operations that could increase the cost of the process

• Completely free of inorganic salts and heavy metals even if they are present in the feedstock

• Only polar compounds are extracted • Solvent removal and recovery is easy since CO2 is a gas at room temperature

242

Carbon Dioxide Capture and Conversion

Soxhlet extraction. However, the extracts from SCCO2 were rich in carotenoids. Pimentel-Moral et al. (2019) showed that SCCO2 could be used as a green solvent for the extraction of bioactive compounds from Hibiscus sabdariffa.

9.3.2 Extraction of cannabinoids Cannabis plants, including the subspecies Cannabis sativa, Cannabis indica, and Cannabis ruderalis, are the basic feedstocks for cannabis products (Rovetto and Aieta, 2017). The plant consists of more than 500 different components, which are grouped into different chemical families such as hydrocarbons, amino acids, terpenes, phenolics, flavonoids, fatty acids, sugars, etc. (Romano and Hazekamp, 2013). Moreover, a particular family of C21 terpenophenolic components found in cannabis plants is of special commercial interest (Romano and Hazekamp, 2013; Rovetto and Aieta, 2017). Cannabis sativa L. plants can be classified based on the chemical phenotypes, which is dependent on the qualitative differences in the amount of main cannabinoids present (Rovetto and Aieta, 2017). On the other hand, the quantity and variety of cannabinoids recovered from C. sativa L. plants are dependent on the extraction methods (Romano and Hazekamp, 2013). Cannabinoids refer to the naturally occurring compounds that are found in cannabis plants. There are more than 66 different cannabinoid compounds out of which delta-9-tetrahydrocannabinol (Δ9-THC) is the most popular (Alcohol and Drug Foundation, 2016). Cannabidiol, an important cannabinoid found in C. sativa L. plants, is known for its medicinal and therapeutic uses. In cancer patients, cannabinoids produce palliative effects by minimizing nausea, pains, and stimulating appetite (Romano and Hazekamp, 2013). Therefore, there have been several studies related to the harvesting and processing of C. sativa L. plants as well as the extraction of essential cannabinoids. Harvesting and processing of C. sativa L. plants either for their oils, fibers, or bioactive components produce vast amounts of by-products that contain several important nutrients. Conventional extraction methods are usually applied to recover the soluble bioactive components (Kitryt˙e et al., 2018). However, such methods have several limitations related to the cost and solvent selectivity as well as their inability to completely recover the target compounds. On the other hand, SCCO2 has been extensively used in the cannabis industry for the extraction of bioactive

Advances in the industrial applications of supercritical carbon dioxide

243

compounds (Foote et al., 2012; Kitryt˙e et al., 2018; Romano and Hazekamp, 2013). SCCO2 is environmentally friendly and does not require the separation of toxic solvents from the oils and extracts. Additionally, through effective control of process temperature and pressure, the high selectivity of the desired compounds could be obtained (Kitryt˙e et al., 2018). Perrotin-Brunel et al. (2010) studied the solubilities of two different cannabinoids: cannabigerol (CBG) and cannabidiol (CBD) in SCCO2. Their results were compared with that of Δ9-THC and cannabinol (CBN). The solubilities of the studied cannabinoids in SCCO2 were in the order of Δ9-THC CBG CBD CBN. Brighenti et al. (2017) compared different techniques for the extraction and analysis of the main nonpsychoactive cannabinoids present in C. sativa L. plants. The techniques include conventional methods such as ultrasound-assisted, solvent maceration, and microwave-assisted technology as well as the SCCO2 extraction. Following the ethanol solvent maceration method at room temperature for 45 min was reported as the most suitable technique for cannabinoid extraction because it produced the highest extraction yield (23 mg/g). On the other hand, SCCO2 extraction also showed promising performance in terms of cannabinoid extraction yield (19 mg/g) when compared with other conventional methods. Moreno et al. (2020) showed that SCCO2 can be used to extract about 449 mg/g CBD from C. sativa L. plant varieties. In addition, the authors studied the effect of using ethanol cosolvent on CBD yield and the extraction pressure. Their results show that the addition of 5% ethanol cosolvent could enhance CBD extraction while increasing the extraction pressure.

9.3.3 Conversion of waste heat into power In general, two main methods are often applied for the utilization of waste heat from several industries and power generation facilities. The waste could be recovered and reused directly or converted into electric power. In terms of energy management and economic perspectives, the conversion of waste heat into electric power is preferable because of the ability to dump excess electricity into the electrical grid (Bianchi et al., 2019). In recent years, power unit systems based on Rankine cycles or steam have been explored as conventional waste heat-to-electricity systems (Bianchi et al., 2019; Marchionni et al., 2020). However, they have

244

Carbon Dioxide Capture and Conversion

several disadvantages related to their efficiencies, temperature, and operational flexibility (Marchionni et al., 2017). Thermodynamic cycles using SCCO2 offer promising alternatives for the conversion of waste thermal heat into electric power. Owing to the thermal stability and favorable thermophysical properties of SCCO2, it leads to high cycle efficiencies when compared with conventional heat-to-power technologies. Fig. 9.2 compares the operating ranges of different waste heat-toelectricity technologies as a function of the heat source temperature level and capacity. As shown in Fig. 9.2, the SCCO2 waste heat-to-electricity system is effective for waste heat source temperature above 700°C. Furthermore, the improved chemical stability of SCCO2 enables the recovery and conversion of waste heat at high temperatures (Marchionni et al., 2017). Due to the advantages of SCCO2, extensive research has been carried out in this field over the last decade. The development of heat exchangers and turbomachines requires further attention. Moreover, future research studies should focus on effective heat exchanger design and scaling up of high pressure and temperature heat exchangers at a low cost.

9.3.4 Catalysis The unique properties of supercritical fluids enable their usage in heterogeneous catalysts testing for different varieties of chemical reactions. The

Figure 9.2 Comparison of SCCO2 with different conventional waste heat-to-power conversion technologies (Marchionni et al., 2020). , organic Rankine cycle; , trilateral flash cycle.

Advances in the industrial applications of supercritical carbon dioxide

245

synthesis of homogeneous and heterogeneous catalysis using supercritical fluids ensures that high reaction rates, improved product selectivity, and the elimination of mass transfer limitations are possible (Knez et al., 2019). Substitution of conventional liquid solvents with supercritical fluids during homogeneously catalyzed reactions has been proven to improve the product yield, reaction rate, and selectivity (Knez et al., 2019). This could be because of the high solubility of the reactant gases in supercritical fluids or the improved diffusion rates under supercritical conditions. The use of SCCO2 for heterogeneous catalyst preparation has been studied by several researchers (Tang et al., 2007; Marin et al., 2013; Knez et al., 2019; Zhang et al., 2020). Tang et al. (2007) showed that supported gold on SCCO2 antisolvent precipitated CeO2 and TiO2 demonstrated high activity for the oxidation of CO. In addition, high dispersion of the metals was observed on the support surface. This was attributed to the defective behavior of the supercritical CO2 antisolvent prepared supports. Marin et al. (2013) used the supercritical CO2 antisolvent precipitation to synthesize several transition metal catalysts for the total oxidation of propane. The metal catalysts prepared include Fe3O4, NiO, CuO, and Co3O4. Moreover, Co3O4 was found to be the most effective catalyst for the total oxidation of propane. SCCO2 was used to dry the heterogeneous Cu/ZnO nanoparticles synthesized by the homogeneous precipitation method with urea as a precipitant (Zhang et al., 2020). The catalysts were used for syngas conversion and CO2 hydrogenation to produce methanol. The harsh operating conditions of the process temperature: 250
400°C and pressure: 10
20 MPa cause catalyst sintering and deactivation. However, the use of SCCO2 drying treatment prevented the sintering of Cu and ZnO particles. Recently, novel bi- and trimetallic bifunctional catalysts, including Pt
Ru, Pt
Zr, and Pt
Ru
Zr, were synthesized over zeolite support using SCCO2 (Al-Rawi et al., 2021). The catalysts were used for the hydroisomerization of n-hexane. The results show an optimal conversion and selectivity of n-hexane of 99.1% and 32.2% with a Pt
Ru/H-ZSM5% catalyst.

9.3.5 Sustainable energy generation SCCO2 could also be exploited for nuclear energy generation as a primary heat carrier in the next-generation nuclear reactors (Moisseytsev and

246

Carbon Dioxide Capture and Conversion

Sienicki, 2009). The reduced chemical reactivity of CO2 with molten sodium facilitates its utilization in the nuclear industry (Marchionni et al., 2020). In addition, the use of SCCO2 for the next-generation nuclear reactors is beneficial toward attaining sustainability goals due to its compact structure and high efficiency (Fan et al., 2020). SCCO2 power cycle has been suggested as a cost-effective approach to minimizing the overall capital cost per unit electric power output in a nuclear power plant (Floyd et al., 2013). Other than its utilization in nuclear reactors, SCCO2 power cycles are also being considered for geothermal applications and in generating concentrated solar power. In geothermal applications, SCCO2 helps in the recovery of geothermal resources at a higher depth. Compared to conventional technologies, SCCO2-assisted technology produces improved efficiency and power output for geothermal energy recovery (Marchionni et al., 2020). The use of SCCO2 to enhance heat recovery in geothermal systems was first proposed in early 2000 and since then there have been several studies on how to improve the efficiency and compares its performance with water (Adams et al., 2014; Garapati et al., 2015; Randolph and Saar, 2011) have been conducted. Moreover, for power generation applications, SCCO2 has been proven to achieve an improved thermodynamic and economic performance in geothermal systems when compared to hot water (Garapati et al., 2015). Furthermore, the injected CO2 could be trapped underground in the geothermal resources (Nanda et al., 2016b). In concentrated solar power, SCCO2 could be used as a working fluid because of its unique thermal properties as well as its low cost. Moreover, SCCO2 has been shown to produce higher efficiency in concentrated solar power due to its ability to withstand higher temperatures without degradation and minimal compression work needed at the near-critical points (Osorio et al., 2016). SCCO2 has also be identified as a chloridefree safe working fluid for concentrated solar power applications (Ehsan et al., 2020).

9.3.6 Biomass pretreatment and recovery of value-added biochemicals SCCO2 acts as a green solvent for the extraction of value-added chemicals, including 5-hydroxymethylfurfural (5-HMF), ethanol, propylene, ethylene and other aromatic compounds from food waste, agricultural residues, and woody biomass (Inoue et al., 2021). SCCO2 could also be

Advances in the industrial applications of supercritical carbon dioxide

247

used as a cost-effective pretreatment method for lignocellulosic biomass before its biological or thermochemical conversion into value-added chemicals and biofuels (Yu et al., 2019). SCCO2 extraction and fractionation were used for the pretreatment of maize stover before hydrolysis and fermentation into ethanol in an integrated maize stove biorefinery (Attard et al., 2015). The results show that SCCO2 improved the downstream hydrolysis and fermentation process. Furthermore, a 40% increase in ethanol yield was observed with SCCO2 pretreatment. Attard et al. (2016) applied SCCO2 as a pretreatment method for Miscanthus biomass before its enzymatic saccharification. The authors observed a 20% increase in sugar yields when Miscanthus was pretreated with SCCO2 compared to the untreated samples. In a similar study, Silveira et al. (2015) showed that SCCO2 is an effective solvent for the pretreatment of sugar cane bagasse before enzymatic hydrolysis. SCCO2 pretreatment could facilitate the removal of lignin molecules in lignocellulosic biomass, thereby enabling easy access to holocellulose (i.e., cellulose and hemicellulose) during thermochemical and biological conversion processes (Yu et al., 2019). Furthermore, the partial structural destruction of biomass materials via SCCO2 extraction could enhance the accessibility of catalysts during thermocatalytic processes (Yu et al., 2019). Moreover, the influence of SCCO2 pretreatment on biomass conversion efficiency is dependent on the type of biomass materials. Yu et al. (2019) studied the impact of SCCO2 extraction toward improving the efficiency of the thermocatalytic conversion of food waste into HMF and levulinic acid. Their results show that SCCO2 could be combined with thermochemical conversion processes to achieve sustainable and carbon-neutral biorefining. A recent study shows that SCCO2 could be used as a reaction medium for the efficient conversion of glucose into 5-HMF (Inoue et al., 2021).

9.3.7 Other industrial applications In recent years, the semiconductor industry has faced the challenges of toxic chemical release as well as increased cost of water and solvent use. Therefore, there have been efforts to minimize toxic chemical release and water consumption. SCCO2 is a promising solvent for many microelectronic applications (Weibel and Ober, 2003). The unique thermochemical properties of SCCO2 ensure that no liquid toxic waste is left behind when used as a solvent in the microelectronics industry.

248

Carbon Dioxide Capture and Conversion

SCCO2 can also be used for precision cleaning applications due to its low surface tension, which ensures improved wettability (Kohli, 2018). Most of the SCCO2-assisted cleaning processes are operated at ambient temperatures. Examples include the cleaning and subsequent drying of nanostructures as well as microstructural surfaces (Jung and Wan, 2012; Qin et al., 2008). SCCO2 can also be used for the cleaning of optical elements, glass surfaces, polymers, soiled banknotes, and metal surfaces (Kohli, 2018). Sheep wool is a major raw material in the textile industries for the manufacturing of clothing materials (Allafi et al., 2021). Furthermore, sheep wool is important to manufacture textiles and garments for commercial use, decoration, and in the aerospace and automotive industry (Patnaik et al., 2015). Wool materials are hygroscopic and possess excellent mechanical properties and high heat retention. Therefore, there has been an increased demand for raw wool in the clothing and textile industry (Patnaik et al., 2015). However, raw sheep wool contains different kinds of impurities such as dirt and wax. In addition, microorganisms such as bacteria could be found in raw sheep wool. Water-based cleaning methods are not environmentally friendly, and they require hazardous volatile organic compounds. Furthermore, they pose several environmental and economic issues (Long et al., 2013). In contrast, SCCO2 is an effective technology that can be used for the simultaneous sterilization, extraction, and drying of raw sheep wool (Allafi et al., 2021). Long et al. (2013) studied the influence of SCCO2 treatment on the crystalline structure and the chemical and thermal properties of the wood fiber. It was observed that SCCO2 influenced both the recrystallization of the polymer chains in the wool and the chemical structure rearrangement. Furthermore, SCCO2 also improved the thermal properties of the wool fiber. SCCO2 is also a promising medium for medical equipment sterilization and decontamination of hazardous materials (Soares et al., 2019). SCCO2 has several benefits compared with conventional sterilization techniques (e.g., gamma irradiation, dry heat/steam, and hydrogen peroxide gas plasma). SCCO2 is inexpensive and readily available (Bernhardt et al., 2015). In addition, SCCO2 does not require ventilation or additional handling. SCCO2 is flexible and easy to implement as a sterilization medium in pharmaceutical, medical, and biomedical fields (Soares et al., 2019). Biomedical polymers made from biomaterials are sensitive to conventional sterilization. However, SCCO2 can inactivate microorganisms, including bacterial spores.

Advances in the industrial applications of supercritical carbon dioxide

249

Table 9.3 Studies on the sterilization of various materials for microorganism inactivation using SCCO2. Materials

Target microorganism for removal

Operating conditions

Reference

Apple juice

• Escherichia coli • Saccharomyces cerevisiae

Ortuño et al. (2014)

Apple juice

• Lactobacillus casei

Biobased membranes

• Bacteria • Yeast

Biofilm

• Bacillus cereus

Corticosteroid powders

• Staphylococcus epidermidis • Bacillus pumilus • Bacillus subtilis

Solid food matrices

• Salmonella enterica • Escherichia coli • Listeria monocytogenes

Wheat grains

• Penicillium oxalicum

• Temperature: 36°C • Time: 5 min • Pressure: 35 MPa • Temperature: 55°C • Time: 30 min • Pressure: 15 MPa • Temperature: 40°C • Time: 1 h • Pressure: 27 MPa • Temperature: 60°C • Time: 2 h • Pressure: 30 MPa • Temperature: 55°C • Time: 30 min • Pressure: 20 MPa • Temperature: 40°C • Time: 1 h • Pressure: 12 MPa • Temperature: 44°C • Time: 1 1 min • Pressure: 10 MPa

Silva et al. (2018)

Scognamiglio et al. (2017)

Park et al. (2013)

Zani et al. (2013)

Galvanin et al. (2014)

Park et al. (2012)

250

Carbon Dioxide Capture and Conversion

Studies on SCCO2 sterilization have focused on different reactor designs and understanding the combination of different parameters that causes the inactivation of microorganisms together with the mechanisms responsible for the inactivation (Bernhardt et al., 2015; Scognamiglio et al., 2017). Bernhardt et al. (2015) showed that the combination of SCCO2 with small amounts of additives, including 0.15% hydrogen peroxide, 0.5% acetic anhydride, and 0.25% water, could inactivate different types of microorganisms in biomedical polymers. The microorganisms removed from SCCO2 sterilization include bacteriophages, fungi, and bacteria. Scognamiglio et al. (2017) studied the effect of SCCO2 treatment on the chemical, mechanical, and biological properties of biobased membranes to be used for surgical operations. Their findings showed that SCCO2 is a promising alternative method for the safe sterilization of biomaterials. A recent study shows that SCCO2 is an effective sterilization technique for the decontamination and reprocessing of personal protective equipment such as N95 respirators, surgical masks, and cloth masks (Bennet et al., 2021). The authors also showed that coronavirus HCoVNL63 and SARS-CoV-2 were inactivated with the use of the SCCO2 sterilization method combined with H2O2 sterilant. Table 9.3 gives a summary of different studies related to the sterilization of various materials using SCCO2.

9.4 Conclusions and perspectives CO2 above its critical temperature and pressure is known as supercritical CO2 (denoted as SCCO2). Beyond the critical points, CO2 displays some unique properties, including improved mass transfer and solvation properties together with low surface tension. These properties enhance its applications in several industrial sectors ranging from the extraction of bioactive compounds, biomass pretreatment, renewable energy generation, conversion of waste heat into power to sterilization fluid. This chapter provides an overview of the unique properties of SCCO2 as well as different industries where it can be applied. Although promising for several industrial applications, the use of SCCO2 poses a variety of challenges. For instance, in concentrated solar power plants, it is often difficult to design high-pressure solar collectors to accommodate SCCO2 as a working fluid. In the conversion of waste heat into power using SCCO2, further research and development is needed for the design and

Advances in the industrial applications of supercritical carbon dioxide

251

scale-up of compact high pressure and high-temperature heat exchangers at a lower cost to minimize leakage and ensure safe operation at operating conditions near the critical point of CO2. Although promising from lab-scale studies, the application of SCCO2 for the extraction of bioactive components and biomass pretreatment should be studied on a large scale. Furthermore, the techno-economic analysis and lifecycle evaluation of the entire process should be performed. This would be invaluable as it helps to determine the economic and environmental impacts of integrating SCCO2 pretreatment into biorefinery operations to produce value-added chemicals.

Acknowledgments The authors would like to thank the Natural Sciences and Engineering Research Council (NSERC) of Canada and the Canada Research Chairs (CRC) program for funding this bioenergy research.

References Adams, B.M., Kuehn, T.H., Bielicki, J.M., Randolph, J.B., Saar, M.O., 2014. On the importance of the thermosiphon effect in CPG (CO2 plume geothermal) power systems. Energy 69, 409
418. Alcohol and Drug Foundation, 2016. What are cannabinoids? Available from: https:// www.news-medical.net/health/What-are-Cannabinoids.aspx (accessed 24.05.21). Allafi, F.A.S., Hossain, M.S., Ab Kadir, M.O., Hakim Shaah, M.A., Lalung, J., Ahmad, M.I., 2021. Waterless processing of sheep wool fiber in textile industry with supercritical CO2: potential and challenges. Journal of Cleaner Production 285, 124819. Al-Rawi, U.A., Sher, F., Hazafa, A., Bilal, M., Lima, E.C., Al-Shara, N.K., et al., 2021. Synthesis of zeolite supported bimetallic catalyst and application in n-hexane hydroisomerization using supercritical CO2. Journal of Environmental Chemical Engineering 9, 105206. Attard, T.M., Theeuwes, E., Gomez, L.D., Johansson, E., Dimitriou, I., Wright, P.C., et al., 2015. Supercritical extraction as an effective first-step in a maize stover biorefinery. RSC Advances 5, 43831
43838. Attard, T.M., McElroy, C.R., Gammons, R.J., Slattery, J.M., Supanchaiyamat, N., Kamei, C.L.A., et al., 2016. Supercritical CO2 extraction as an effective pretreatment step for wax extraction in a miscanthus biorefinery. ACS Sustainable Chemistry & Engineering 4, 5979
5988. Barbosa, H.M.A., De Melo, M.M.R., Coimbra, M.A., Passos, C.P., Silva, C.M., 2014. Optimization of the supercritical fluid coextraction of oil and diterpenes from spent coffee grounds using experimental design and response surface methodology. Journal of Supercritical Fluids 85, 165
172. Bennet, D., Harris, A.F., Lacombe, J., Brooks, C., Bionda, N., Strickland, A.D., et al., 2021. Evaluation of supercritical CO2 sterilization efficacy for sanitizing personal protective equipment from the coronavirus SARS-CoV-2. Science of the Total Environonment 780, 146519.

252

Carbon Dioxide Capture and Conversion

Bernhardt, A., Wehrl, M., Paul, B., Hochmuth, T., Schumacher, M., Schütz, K., et al., 2015. Improved sterilization of sensitive biomaterials with supercritical carbon dioxide at low temperature. PLoS One 10, 129205. Bianchi, G., Panayiotou, G.P., Aresti, L., Kalogirou, S.A., Florides, G.A., Tsamos, K., et al., 2019. Estimating the waste heat recovery in the European Union Industry. Energy, Ecology and Environment 4, 211
221. Brighenti, V., Pellati, F., Steinbach, M., Maran, D., Benvenuti, S., 2017. Development of a new extraction technique and HPLC method for the analysis of non-psychoactive cannabinoids in fibre-type Cannabis sativa L. (hemp). Journal of Pharmaceutical and Biomedical Analysis 143, 228
236. Chauvet, M., Sauceau, M., Fages, J., 2017. Extrusion assisted by supercritical CO2: a review on its application to biopolymers. Journal of Supercritical Fluids 120, 408
420. Crabtree, R.H., Michael, D., Mingos, P., 2007. Comprehensive organometallic chemistry III. da Silva, R.P.F.F., Rocha-Santos, T.A.P., Duarte, A.C., 2016. Supercritical fluid extraction of bioactive compounds. Trends in Analytical Chemistry 76, 40
51. Ehsan, M.M., Guan, Z., Gurgenci, H., Klimenko, A., 2020. Feasibility of dry cooling in supercritical CO2 power cycle in concentrated solar power application: review and a case study. Renewable and Sustainable Energy Reviews 132, 110055. Espinosa-Pardo, F.A., Martinez, J., Martinez-Correa, H.A., 2014. Extraction of bioactive compounds from peach palm pulp (Bactris gasipaes) using supercritical CO2. Journal of Supercritical Fluids 93, 2
6. Fan, G., Li, H., Du, Y., Zheng, S., Chen, K., Dai, Y., 2020. Preliminary conceptual design and thermo-economic analysis of a combined cooling, heating and power system based on supercritical carbon dioxide cycle. Energy 203, 117842. Floyd, J., Alpy, N., Moisseytsev, A., Haubensack, D., Rodriguez, G., Sienicki, J., et al., 2013. A numerical investigation of the sCO2 recompression cycle off-design behaviour, coupled to a sodium cooled fast reactor, for seasonal variation in the heat sink temperature. Nuclear Engineering and Design 260, 78
92. Foote, H.G., Gb, H.H.U., Victor, D., 2012. Extraction of pharmaceutically active cannabinoids from plant materials. Google Patents 37, 507
511. Galvanin, F., De Luca, R., Ferrentino, G., Barolo, M., Spilimbergo, S., Bezzo, F., 2014. Bacterial inactivation on solid food matrices through supercritical CO2: a correlative study. Journal of Food Engineering 120, 146
157. Garapati, N., Randolph, J.B., Saar, M.O., 2015. Brine displacement by CO2, energy extraction rates, and lifespan of a CO2-limited CO2-Plume Geothermal (CPG) system with a horizontal production well. Geothermics 55, 182
194. Hans, N., Pattnaik, F., Malik, A., Nanda, S., Kumar, V., Dalai, A.K., et al., 2021. Algalderived physiologically active nutraceuticals: dietary supplements, vitamins, carotenoids, fatty acids and other novel products. In: Dalai, A.K., Goud, V.V., Nanda, S., Borugadda, V.B. (Eds.), Algal Biorefinery: Developments, Challenges and Opportunities. Routledge, Abingdon, United Kingdom, pp. 197
230. Inoue, R., Agutaya, J.K.C.N., Quitain, A.T., Sasaki, M., Cocero, M.J., Kida, T., 2021. Supercritical CO2
subcritical H2O system: a green reactive separation medium for selective conversion of glucose to 5-hydroxymethylfurfural. Journal of Supercritical Fluids 168, 105079. Jung, J.W., Wan, J., 2012. Supercritical CO2 and ionic strength effects on wettability of silica surfaces: equilibrium contact angle measurements. Energy and Fuels 26, 6053
6059. Kamiloglu, S., Tomas, M., Ozdal, T., Yolci-Omeroglu, P., Capanoglu, E., 2021. Bioactive component analysis. Innovative Food Analysis. Elsevier, pp. 41
65.

Advances in the industrial applications of supercritical carbon dioxide

253

Kitryt˙e, V., Bagdonait˙e, D., Venskutonis, P.R., 2018. Biorefining of industrial hemp (Cannabis sativa L.) threshing residues into cannabinoid and antioxidant fractions by supercritical carbon dioxide, pressurized liquid and enzyme-assisted extractions. Food Chemistry 267, 420
429. ˇ Panti´c, M., Cör, D., Novak, Z., Knez Hrnˇciˇc, M., 2019. Are supercritical fluids Knez, Z., solvents for the future? Chemical Engineering and Processing - Process Intensification 141, 107532. Kohli, R., 2018. Applications of supercritical carbon dioxide for removal of surface contaminants, Developments in Surface Contamination and Cleaning: Applications of Cleaning Techniques, Vol. 11. Elsevier, pp. 209
249. Lindsey, R., 2020. Climate Change: Atmospheric Carbon Dioxide. Climate.gov. Available from: https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide#:B:text The%20global%20average% 20atmospheric%20carbon,plus%20or%20minus%200.1%20ppm (accessed 15.05.21). Long, J.J., Cui, C.L., Wang, L., Xu, H.M., Yu, Z.J., Bi, X.P., 2013. Effect of treatment pressure on wool fiber in supercritical carbon dioxide fluid. Journal of Cleaner Production 43, 52
58. Marchionni, M., Bianchi, G., Tsamos, K.M., Tassou, S.A., 2017. Techno-economic comparison of different cycle architectures for high temperature waste heat to power conversion systems using CO2 in supercritical phase. Energy Procedia 123, 305
312. Marchionni, M., Bianchi, G., Tassou, S.A., 2020. Review of supercritical carbon dioxide (sCO2) technologies for high-grade waste heat to power conversion. SN Applied Sciences 2, 1
13. Marin, R.P., Kondrat, S.A., Pinnell, R.K., Davies, T.E., Golunski, S., Bartley, J.K., et al., 2013. Green preparation of transition metal oxide catalysts using supercritical CO2 anti-solvent precipitation for the total oxidation of propane. Applied Catalysis B: Environmental 140-141, 671
679. Moisseytsev, A., Sienicki, J.J., 2009. Investigation of alternative layouts for the supercritical carbon dioxide Brayton cycle for a sodium-cooled fast reactor. Nuclear Engineering and Design 239, 1362
1371. Moreno, T., Montanes, F., Tallon, S.J., Fenton, T., King, J.W., 2020. Extraction of cannabinoids from hemp (Cannabis sativa L.) using high pressure solvents: an overview of different processing options. Journal of Supercritical Fluids 161, 104850. Mukherjee, A., Okolie, J.A., Abdelrasoul, A., Niu, C., Dalai, A.K., 2019. Review of post-combustion carbon dioxide capture technologies using activated carbon. Journal of Environmental Science 83, 46
63. Naik, S., Goud, V.V., Rout, P.K., Dalai, A.K., 2010. Supercritical CO2 fractionation of bio-oil produced from wheat-hemlock biomass. Bioresource Technology 101, 7605
7613. Nanda, S., Berruti, F., 2021a. A technical review of bioenergy and resource recovery from municipal solid waste. Journal of Hazardous Materials 403, 123970. Nanda, S., Berruti, F., 2021b. Municipal solid waste management and landfilling technologies: a review. Environmental Chemistry Letters 19, 1433
1456. Nanda, S., Berruti, F., 2021c. Thermochemical conversion of plastic waste to fuels: a review. Environmental Chemistry Letters 19, 123
148. Nanda, S., Mohanty, P., Pant, K.K., Naik, S., Kozinski, J.A., Dalai, A.K., 2013. Characterization of North American lignocellulosic biomass and biochars in terms of their candidacy for alternate renewable fuels. BioEnergy Research 6, 663
677. Nanda, S., Mohammad, J., Reddy, S.N., Kozinski, J.A., Dalai, A.K., 2014. Pathways of lignocellulosic biomass conversion to renewable fuels. Biomass Conversion and Biorefinery 4, 157
191.

254

Carbon Dioxide Capture and Conversion

Nanda, S., Dalai, A.K., Berruti, F., Kozinski, J.A., 2016a. Biochar as an exceptional bioresource for energy, agronomy, carbon sequestration, activated carbon and specialty materials. Waste and Biomass Valorization 7, 201
235. Nanda, S., Reddy, S.N., Mitra, S.K., Kozinski, J.A., 2016b. The progressive routes for carbon capture and sequestration. Energy Science & Engineering 4, 99
122. Nanda, S., Rana, R., Zheng, Y., Kozinski, J.A., Dalai, A.K., 2017. Insights on pathways for hydrogen generation from ethanol. Sustainable Energy & Fuels 1, 1232
1245. Nanda, S., Pattnaik, F., Borugadda, V.B., Dalai, A.K., Kozinski, J.A., Naik, S., 2021. Catalytic and noncatalytic upgrading of bio-oil to synthetic fuels: an introductory review. In: Dalai, A.K., Dadyburjor, D.B., Zheng, Y., Duan, A., Roberts, W., Nanda, S. (Eds.), Catalytic and Noncatalytic Upgrading of Oils. In: 1379. ACS Symposium Series, Washington, DC, pp. 1
28. Nguyen, T.D., Tran, T.V., Singh, S., Phuong, P.T.T., Bach, L.G., Nanda, S., et al., 2020. Conversion of carbon dioxide into formaldehyde. In: Inamuddin, A.A.M., Eric, L. (Eds.), Conversion of Carbon Dioxide into Hydrocarbons. Vol. 2 Technology. Springer Nature, Singapore, pp. 159
183. Nowak, S., Winter, M., 2017. The role of sub- and supercritical CO2 as “processing solvent” for the recycling and sample preparation of lithium ion battery electrolytes. Molecules (Basel, Switzerland) 22, 403. Okolie, J.A., Rana, R., Nanda, S., Dalai, A.K., Kozinski, J.A., 2019. Supercritical water gasification of biomass: a state-of-the-art review of process parameters, reaction mechanisms and catalysis. Sustainable Energy and Fuels 3, 578
598. Okolie, J.A., Nanda, S., Dalai, A.K., Berruti, F., Kozinski, J.A., 2020. A review on subcritical and supercritical water gasification of biogenic, polymeric and petroleum wastes to hydrogen-rich synthesis gas. Renewable and Sustainable Energy Reviews 119, 109546. Okolie, J.A., Mukherjee, A., Nanda, S., Dalai, A.K., Kozinski, J.A., 2021a. Nextgeneration biofuels and platform biochemicals from lignocellulosic biomass. International Journal of Energy Research 45, 14145
14169. Okolie, J.A., Nanda, S., Dalai, A.K., Kozinski, J.A., 2021b. Techno-economic evaluation and sensitivity analysis of a conceptual design for supercritical water gasification of soybean straw to produce hydrogen. Bioresource Technology 331, 125005. Ortuño, C., Quiles, A., Benedito, J., 2014. Inactivation kinetics and cell morphology of E. coli and S. cerevisiae treated with ultrasound-assisted supercritical CO2. Food Research International 62, 955
964. Osorio, J.D., Hovsapian, R., Ordonez, J.C., 2016. Dynamic analysis of concentrated solar supercritical CO2-based power generation closed-loop cycle. Applied Thermal Engineering 93, 920
934. Parakh, P.D., Nanda, S., Kozinski, J.A., 2020. Eco-friendly transformation of waste biomass to biofuels. Current Biochemical Engineering 6, 120
134. Park, H.S., Lee, Y.H., Kim, W., Choi, H.J., Kim, K.H., 2012. Disinfection of wheat grains contaminated with Penicillium oxalicum spores by a supercritical carbon dioxidewater cosolvent system. International Journal of Food Microbiology 156, 239
244. Park, H.S., Choi, H.J., Kim, M.D., Kim, K.H., 2013. Addition of ethanol to supercritical carbon dioxide enhances the inactivation of bacterial spores in the biofilm of Bacillus cereus. International Journal of Food Microbiology 166, 207
212. Patnaik, A., Mvubu, M., Muniyasamy, S., Botha, A., Anandjiwala, R.D., 2015. Thermal and sound insulation materials from waste wool and recycled polyester fibers and their biodegradation studies. Energy and Building 92, 161
169. Patra, B.R., Mukherjee, A., Nanda, S., Dalai, A.K., 2021. Biochar production, activation and adsorptive applications: a review. Environmental Chemistry Letters 19, 2237
2259.

Advances in the industrial applications of supercritical carbon dioxide

255

Pattnaik, F., Nanda, S., Mohanty, S., Dalai, A.K., Kumar, V., Ponnusamy, S.K., Naik, S., 2022. Cannabis: Chemistry, extraction and therapeutic applications. Chemosphere 289, 133012. Pereira, C.G., Meireles, M.A.A., 2010. Supercritical fluid extraction of bioactive compounds: fundamentals, applications and economic perspectives. Food and Bioprocess Technology 3, 340
372. Perrotin-Brunel, H., Kroon, M.C., Van Roosmalen, M.J.E., Van Spronsen, J., Peters, C. J., Witkamp, G.J., 2010. Solubility of non-psychoactive cannabinoids in supercritical carbon dioxide and comparison with psychoactive cannabinoids. Journal of Supercritical Fluids 55, 603
608. Pimentel-Moral, S., Borrás-Linares, I., Lozano-Sánchez, J., Arráez-Román, D., MartínezFérez, A., Segura-Carretero, A., 2019. Supercritical CO2 extraction of bioactive compounds from Hibiscus sabdariffa. Journal of Supercritical Fluids 147, 213
221. Qi, H., Gui, N., Yang, X., Tu, J., Jiang, S., 2018. The application of supercritical CO2 in nuclear engineering: a review. Journal of Computational Multiphase Flows 10, 149
158. Qin, Y., Yang, X., Zhu, Y., Ping, J., 2008. Molecular dynamics simulation of interaction between supercritical CO2 fluid and modified silica surfaces. Journal of Physical Chemistry C 112, 12815
12824. Rana, R., Nanda, S., Kozinski, J.A., Dalai, A.K., 2018. Investigating the applicability of Athabasca bitumen as a feedstock for hydrogen production through catalytic supercritical water gasification. Journal of Environmental Chemical Engineering 6, 182
189. Rana, R., Nanda, S., Maclennan, A., Hu, Y., Kozinski, J.A., Dalai, A.K., 2019. Comparative evaluation for catalytic gasification of petroleum coke and asphaltene in subcritical and supercritical water. Journal of Energy Chemistry 31, 107
118. Rana, R., Nanda, S., Reddy, S.N., Dalai, A.K., Kozinski, J.A., Gökalp, I., 2020. Catalytic gasification of light and heavy gas oils in supercritical water. Journal of the Energy Institute 93, 2025
2032. Randolph, J.B., Saar, M.O., 2011. Combining geothermal energy capture with geologic carbon dioxide sequestration. Geophysical Research Letters 38, 10. Reddy, S.N., Ding, N., Nanda, S., Dalai, A.K., Kozinski, J.A., 2014a. Supercritical water gasification of biomass in diamond anvil cells and fluidized beds. Biofuels, Bioproducts and Biorefining 8, 728
737. Reddy, S.N., Nanda, S., Dalai, A.K., Kozinski, J.A., 2014b. Supercritical water gasification of biomass for hydrogen production. International Journal of Hydrogen Energy 39, 6912
6926. Reddy, S.N., Nanda, S., Sarangi, P.K., 2018. Applications of supercritical fluids for biodiesel production. In: Sarangi, P.K., Nanda, S., Mohanty, P. (Eds.), Recent Advancements in Biofuels and Bioenergy Utilization. Springer Nature, Singapore, pp. 261
284. Romano, L.L., Hazekamp, A., 2013. Cannabis Oil: chemical evaluation of an upcoming cannabis-based medicine. Cannabinoids 1, 1
11. Rovetto, L.J., Aieta, N.V., 2017. Supercritical carbon dioxide extraction of cannabinoids from Cannabis sativa L. Journal of Supercritical Fluids 129, 16
27. Sahena, F., Zaidul, I.S.M., Jinap, S., Karim, A.A., Abbas, K.A., Norulaini, N.A.N., et al., 2009. Application of supercritical CO2 in lipid extraction
a review. Journal of Food Engineering 95, 240
253. Sánchez-Camargo, A., del, P., Valdés, A., Sullini, G., García-Cañas, V., Cifuentes, A., et al., 2014. Two-step sequential supercritical fluid extracts from rosemary with enhanced anti-proliferative activity. Journal of Functional Foods 11, 293
303. Sarangi, P.K., Nanda, S., 2020. Biohydrogen production through dark fermentation. Chemical Engineering & Technology 43, 601
612.

256

Carbon Dioxide Capture and Conversion

Sarker, T.R., Nanda, S., Dalai, A.K., Meda, V., 2021. A review of torrefaction technology for upgrading lignocellulosic biomass to solid biofuels. BioEnergy Research 14, 645
669. Scognamiglio, F., Blanchy, M., Borgogna, M., Travan, A., Donati, I., Bosmans, J.W.A. M., et al., 2017. Effects of supercritical carbon dioxide sterilization on polysaccharidic membranes for surgical applications. Carbohydrate Polymers 173, 482
488. Serra, A.T., Seabra, I.J., Braga, M.E.M., Bronze, M.R., De Sousa, H.C., Duarte, C.M.M., 2010. Processing cherries (Prunus avium) using supercritical fluid technology. Part 1: recovery of extract fractions rich in bioactive compounds. Journal of Supercritical Fluids 55, 184
191. Shafiqah, M.N.N., Tran, H.N., Nguyen, T.D., Phuong, P.T.T., Abdullah, B., Lam, S.S., et al., 2020. Ethanol CO2 reforming on La2O3 and CeO2-promoted Cu/Al2O3 catalysts for enhanced hydrogen production. International Journal of Hydrogen Energy 45, 18398
18410. Silva, E.K., Alvarenga, V.O., Bargas, M.A., Sant’Ana, A.S., Meireles, M.A.A., 2018. Nonthermal microbial inactivation by using supercritical carbon dioxide: synergic effect of process parameters. Journal of Supercritical Fluids 139, 97
104. Silveira, M.H.L., Vanelli, B.A., Corazza, M.L., Ramos, L.P., 2015. Supercritical carbon dioxide combined with 1-butyl-3-methylimidazolium acetate and ethanol for the pretreatment and enzymatic hydrolysis of sugarcane bagasse. Bioresource Technology 192, 389
396. Singh, S., Kumar, R., Setiabudi, H.D., Nanda, S., Vo, D.V.N., 2018. Advanced synthesis strategies of mesoporous SBA-15 supported catalysts for catalytic reforming applications: a state-of-the-art review. Applied Catalysis A: General 559, 57
74. Siqueira, R.M., Freitas, G.R., Peixoto, H.R., Nascimento, J.F.D., Musse, A.P.S., Torres, A.E.B., et al., 2017. Carbon dioxide capture by pressure swing adsorption. Energy Procedia 114, 2182
2192. Soares, G.C., Learmonth, D.A., Vallejo, M.C., Davila, S.P., González, P., Sousa, R.A., et al., 2019. Supercritical CO2 technology: the next standard sterilization technique? Material Science and Engineering 99, 520
540. Tang, Z.R., Edwards, J.K., Bartley, J.K., Taylor, S.H., Carley, A.F., Herzing, A.A., et al., 2007. Nanocrystalline cerium oxide produced by supercritical antisolvent precipitation as a support for high-activity gold catalysts. Journal of Catalysis 249, 208
219. Tcvetkov, P., Cherepovitsyn, A., Fedoseev, S., 2019. The changing role of CO2 in the transition to a circular economy: review of carbon sequestration projects. Sustainability 11, 5834. Weibel, G.L., Ober, C.K., 2003. An overview of supercritical CO2 applications in microelectronics processing. Microelectronic Engineering 65, 145
152. Yu, I.K.M., Attard, T.M., Chen, S.S., Tsang, D.C.W., Hunt, A.J., Jérôme, F., et al., 2019. Supercritical carbon dioxide extraction of value-added products and thermochemical synthesis of platform chemicals from food waste. ACS Sustainable Chemistry and Engineering 7, 2821
2829. Zani, F., Veneziani, C., Bazzoni, E., Maggi, L., Caponetti, G., Bettini, R., 2013. Sterilization of corticosteroids for ocular and pulmonary delivery with supercritical carbon dioxide. Internation Journal of Pharmaceuticals 450, 218
224. Zhang, P., Araki, Y., Feng, X., Li, H., Fang, Y., Chen, F., et al., 2020. Urea-derived Cu/ ZnO catalyst being dried by supercritical CO2 for low-temperature methanol synthesis. Fuel 268, 117213.

CHAPTER 10

Application of membrane technology for CO2 capture and separation Wai Fen Yong1, Can Zeng Liang2 and Chaitanyakumar Reddy Pocha1 1

School of Energy and Chemical Engineering, Xiamen University Malaysia, Selangor Darul Ehsan, Selangor, Malaysia Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore

2

Abbreviations P84 [C6mim] [Tf2N] 6FDA-mPDA Al2O3 CCS CMS CNTs CTCs CVD PDMC EA(H2)-TB F-SPEEK GOs MOFs MF SSZ MMMs NIPS PTMSP PANI PBI PBOs

(BTDA-TDI/MDI) co-polyimide of 3,30 4,40 -benzophenone tetracarboxylic dianhydride and 80% methylphenylene-diamine/20% methylene diamine 1-hexyl-3-methyl-imidazolium bis (trifluoromethylsulphonyl) imide 4,40 -(hexafluoroisopropylidene)diphthalic dianhydride-m-phenylenediamine alumina carbon capture and storage carbon molecular sieve carbon nanotubes charge transfer complexes chemical vapor deposition cross-linkable polyimide ethanoanthracene fluorinated poly(ether ether ketone) graphene oxides metal-organic frameworks microfiltration microporous aluminosilicate having a chabazite framework mixed matrix membranes non-solvent induced phase separation poly(trimethylsilylpropyne) polyaniline polybenzimidazole polybenzoxazoles

Carbon Dioxide Capture and Conversion DOI: https://doi.org/10.1016/B978-0-323-85585-3.00007-9

© 2022 Elsevier B.V. All rights reserved.

257

258

Carbon Dioxide Capture and Conversion

PDMS PES/PESU PEG POSS PIMs PSf PU PVP SEM SiO2 SAPO-34 SPEEK sPPSU TEOS TIPS TR TiO2 TB UF UF6 XRD YSZ ZSM-5 ZIFs ZrO2

polydimethylsiloxane polyethersulfone polyethylene glycol polyhedral oligomeric silsesquioxane polymers of intrinsic microporosity polysulfone polyurethane polyvinylpyrrolidone scanning electron microscope silica silicoaluminophosphate-34 sulfonated poly(ether ether ketone) sulfonated polyphenylsulfone tetraethoxysilane thermally induced phase separation thermally rearranged titania Tröger’s base ultrafiltration uranium hexafluoride X-ray diffraction Yttria-stabilized zirconia zeolite scony mobil five zeolitic imidazolate frameworks zirconia

List of symbols αi=j

selectivity (dimensionless) volume fraction of a polymer (dimensionless) A total effective area of hollow fibers (cm2) D outer diameter of hollow fibers (cm) Di diffusion coefficient of gas species i (cm2/s) l effective length of fibers (cm) Mi molecular weight of gas i (g/mol) Mj molecular weight of gas j (g/mol) n total number of hollow fibers in one testing module ΔP transmembrane pressure (cmHg) Pb permeability of the polymer blend (Barrer) Peff effective permeability of the MMMs (Barrer) Pi gas permeability of gas species i (Barrer) Qi gas flux of species i (cm3/s) Si solubility coefficient of gas species i (cm3(STP)/(cm3.atm)) Tg glass transition temperature (°C) w mass fraction of a polymer (dimensionless)

Application of membrane technology for CO2 capture and separation

259

10.1 Introduction Global warming has become one of the most pressing environmental issues, which is caused by the rapid rise of carbon dioxide (CO2) concentration in the atmosphere (Merkel et al., 2010; Rogelj et al., 2016; Wang et al., 2016; Williamson, 2016). The atmospheric CO2 concentration has reached about 420 ppm in 2020, which is approximately a 35% increment since 1960 (2020). The increasing global energy consumption caused by the burning of fossil fuels (e.g., coal, oil, and hydrocarbon gases) is one of the reasons for global warming (Fu et al., 2015; Hashim et al., 2010; Merkel et al., 2010). To combat global warming, the Paris Agreement (2015) aims to strengthen the global response by keeping the temperature rise below 2°C by 2100 (Rogelj et al., 2016; Williamson, 2016). Therefore, there is an urgent need to mitigate anthropogenic CO2 emission by the means of carbon capture and storage (CCS) (Merkel et al., 2010; Rogelj et al., 2016). Generally, the CCS includes two strategies (Merkel et al., 2010): (1) post-combustion CO2 capture from the flue gas of fossil-fueled power plants and or burners; (2) pre-combustion CO2 capture from natural gas, syngas, and biogas. Although the CO2 capture and separation from different gas streams or sources can be achieved by the well-established processes such as cryogenic distillation and absorption/adsorption, these processes require high operating costs, are energy-intensive, and have potential environmental concerns (Baker, 2002; Ismail et al., 2015; Merkel et al., 2010). Membrane gas separations have been commercialized since the late 1970s, and are proven to be environmentally friendly, costeffective, and energy-efficient as compared to the conventional separation processes (Baker, 2012; Henis and Tripodi, 1983). A membrane can separate and purify gases because of different transport rates of gas molecules across the membrane. The main driving force for the gas transport across a membrane is the concentration or the pressure gradient (Baker, 2012; Ismail et al., 2015; Henis and Tripodi, 1981; Liang et al., 2019). The application of membrane-based processes for CO2 capture and separation is promising and has gained paramount interests and efforts from academia and industries (Adewole et al., 2013; Baker, 2002; Baker and Lokhandwala, 2008; Merkel et al., 2010; Wang et al., 2016; Xie et al., 2019; Yang et al., 2008; Yeo et al., 2012).

260

Carbon Dioxide Capture and Conversion

Currently, polymeric membranes dominate membrane-based processes for CO2 capture and separation (Baker, 2012; Wang et al., 2016). However, polymer membranes followed the Robeson trade-off according to which a highly permeable membrane tends to have low selectivity and vice versa (Park et al., 2017; Robeson, 2008; Wang et al., 2016). Moreover, polymeric membranes often suffer from aging and plasticization, particularly for the gas streams containing condensable gases such as CO2 (Bos et al., 1999; Liang et al., 2019; Wang et al., 2014; Yong et al., 2015). The plasticization reduces the selectivity and thus deteriorates the membrane separation performance. To overcome these limitations, inorganic membranes such as carbon molecular sieve (CMS) membranes, ceramic membranes, and zeolite membranes are being identified and developed as alternative candidates for CO2 separation (Baker, 2012; Chen et al., 2014; Kosinov et al., 2016; Li et al., 2015; Saufi and Ismail, 2004). Besides, membranes prepared from the hybrid of organic and inorganic materials such as mixed matrix membranes (MMMs) are also promising for CO2 separations (Chung et al., 2007; Yong and Zhang, 2021). The CO2 capture and separation from different CO2 sources through membrane technologies are of great interest and importance. An updated summary and introduction for membrane materials and membrane fabrications are important. Thus, the objective of this chapter is to provide a general and comprehensive summary of the membrane-based technologies for the application of CO2 capture and separation. This chapter will cover the background and theories of the membranes, the gas transport mechanism through the membranes, and membrane fabrication strategies. Both polymeric membranes and inorganic membranes will be discussed. The polymeric membranes including polymer blends and MMMs and the inorganic membranes such as CMS membranes, ceramic membranes, and zeolite membranes will be elucidated. Finally, prospects and perspectives of membrane separation for CO2 capture are briefly outlined.

10.2 Transport mechanisms for gas separation The basic principle behind the utilization of membranes for gas separation is their ability to selectively permeate the gases through their surface. Membranes can be categorized into porous and nonporous structures depending on the fabrication procedures. The transport properties in porous membranes are extremely dependent on the microstructures of the membrane, including the size of pores, porosity, and pore distribution.

Application of membrane technology for CO2 capture and separation

261

Some typical porous inorganic membranes are zeolites, CMS, and ceramic membranes. The use of these membranes dates back to the 1950s when the alumina membranes were first used to separate UF6 isotopes with a selectivity of only 1 (Uhlhorn and Burggraaf, 1991). The separation mechanism in porous membranes is either convective flow, Knudsen diffusion, or molecular sieving. Whereas in a nonporous or dense membrane, gases are separated using the solution-diffusion mechanism. Moreover, some of the rubbery polymers, such as polydimethylsiloxane (PDMS), polyurethane (PU), and polyisoprene, and the glassy polymers, such as polysulfone (PSf), polyimides, and polycarbonates, are widely used in gas separation (Abhisha et al., 2018).

10.2.1 Diffusion in porous membranes Porous membranes such as inorganic membranes have attracted much interest in the last few decades because of their suitability in high temperatures and pressures compared to polymeric membranes. In porous inorganic membranes, a thin porous layer is cast onto a ceramic support, which provides mechanical strength while minimizing the mass transfer resistance. Carbon and zeolite membranes are often supported by different substrates, such as alumina, zirconia, and porous stainless steel (Iulianelli et al., 2011). In addition, these membranes show high permeability because of their porous support with low selectivity. Gas permeates through porous membranes by convective flow with pore sizes range within 0.1
10 μm. In convective flow, separation of gas components is not possible since the mean free path of the gas penetrants is much smaller than the radius of the membrane pores. The mean free path is the average distance traveled by a moving gas molecule before the collision with another gas molecule. Knudsen diffusion occurs when the mean free path of the diffusing gas molecules is larger than the pore diameter and the gas density is low. The membrane pore size is typically smaller than 0.1 μm. The gas
pair selectivity of the respective two gases given by the expression: rffiffiffiffiffiffi Mj αi=j (10.1) Mi where Mi and Mj are the gas molecular weights of gas i and gas j, respectively. The relatively low selectivity in membranes with Knudsen diffusion made them unfavorable for industrial application. Molecular sieving takes into effect

262

Carbon Dioxide Capture and Conversion

when the diameter of the pores is between 5 and 10 Å and the separation occurs through size exclusion of larger molecules, allowing only smaller ones to permeate. Examples of inorganic membranes that act as molecular sieves are zeolites and carbon membranes (CMS) (Uhlhorn and Burggraaf, 1991).

10.2.2 Diffusion in nonporous membranes The transport mechanism for the nonporous or dense membranes is the solution
diffusion model. It was first proposed by Sir Thomas Graham in the 19th century (Wijmans and Baker, 1995). According to this model, the gas species first adsorbs onto the membrane surface upstream where the pressure is high. Then, the gas diffuses through the polymer matrix by a driving force. Lastly, the gas is desorbed from downstream at the lower pressure side. The driving force for this process is the pressure gradient or concentration gradient across the membrane. Fig. 10.1 shows the illustration of the solution
diffusion model with CO2 (gas i) and CH4 (gas j) as the gas species (Monsalve-Bravo and Bhatia, 2018). The assumptions of this model are as follows (Baker, 2012): 1. An equilibrium exists between the gases on both membrane sides and the membrane at the interface. 2. The pressure applied throughout the membrane is uniform.

Sorption

Desorption

Low Pressure

High Pressure Membrane

Figure 10.1 Schematic of the solution
diffusion model.

Gas i Gas j

Application of membrane technology for CO2 capture and separation

263

Permeability and selectivity are the two important parameters in determining gas separation efficiency. The permeability of gas species i is defined as a product of solubility coefficient and diffusivity coefficient as shown below Pi

Di

Si

(10.2)

where Pi is the gas permeability of gas species i expressed as Barrer (1 Barrer 1 10 10 cm3(STP)cm/(cm2s.cmHg)), Di is the diffusion coefficient of gas species i (cm2/s), and Si is the solubility coefficient of gas species i (cm3(STP)/(cm3.atm)). The gas permeance or pressure-normalized flux of gas species i in a hollow fiber membrane is determined as: Pi L Pi L

Qi AΔP

(10.3)

Qi nπDlΔP

(10.4)

where Pi/L is the gas permeance of species i of hollow fibers in GPU (1 GPU 1x10 6 cm3(STP)/(cm2s.cmHg)), Qi is the gas flux of species i (cm3/s), A is the total effective area of hollow fibers (cm2), ΔP is the transmembrane pressure (cmHg), n is the total number of hollow fibers in one testing module, D is the outer diameter of hollow fibers (cm), and l is the effective length of fibers (cm). The ideal permselectivity in a membrane is the ratio of gas permeabilities as described in the following equations: αi=j

αi=j

Pi Pj

(10.5)

Di S i Dj S j

(10.6)

where αi=j is the selectivity of a mixture of gas i and j. Polymeric membranes show a permeability-selectivity trade-off such that a membrane with a high permeability has low selectivity and vice versa. The trade-off for membranes is plotted as the Robeson upper bound (Comesaña-Gándara et al., 2019; Robeson, 2008). For the nonporous structure of the polymeric membranes, gases travel through the

264

Carbon Dioxide Capture and Conversion

passages formed in the polymer matrix because of the thermally induced motion of the polymer chains. Thus, the transport rates depend on the movements of gases in these passages.

10.3 Membrane preparation The increasing research in membrane technology signifies that membranes are becoming the main focus for industrial gas separation applications such as CO2 capture and air separation. The fabrication of defect-free membranes is incredibly important as it played a vital role in the commercialization of membranes for reverse osmosis and ultrafiltration in the late 1960s (Baker, 2012). Moreover, defect-free membranes are prepared from the selection of best materials combined with the most appropriate membrane preparation methods. Generally, membranes can be fabricated as a flat sheet or in the form of a hollow fiber. Detailed hollow fiber membrane preparation is reported elsewhere (Lau and Yong, 2021). Both the polymeric and the inorganic materials are used to prepare the membrane depending on the application. While the polymeric membranes are preferred for their ease of fabrication, diversities, and simplicity in scaling up, the inorganic membranes are chosen for their better chemical, structural, and thermal stability. Different techniques are used to prepare various types of isotropic and anisotropic membranes. For polymeric membranes, the selection of technique relies on the type of polymer and the desired membrane structure (Lalia et al., 2013). Some of the widely used techniques include phase inversion, interfacial polymerization, and electrospinning. For inorganic membranes, the choice of technique generally lies on the material preferred and the pore size of the membrane. Inorganic membranes are usually prepared from slip casting, sol-gel process, pyrolysis, and chemical vapor deposition (CVD).

10.3.1 Preparation of polymeric membranes 10.3.1.1 Phase inversion technique The phase inversion technique, also known as phase separation, has been widely used to prepare polymeric membranes. It was first used by Loeb and Sourirajan to prepare anisotropic membranes to fabricate from cellulose acetate for reverse osmosis in the 1960s (Loeb and Sourirajan, 1963). The resulting membrane provided high flux and had better permeability than isotropic membranes, which were previously produced from the same material.

Application of membrane technology for CO2 capture and separation

265

As the name implies, the phase inversion method involves precipitating the single-phase casting solution into two separate phases, namely polymer-rich and polymer-lean phase. To prepare the casting solution, the polymer is first dissolved in a known solvent. Theoretically, the separation is possible because of the large miscibility gap on the ternary diagram. Within this region, the polymer-solvent system is not stable (Figoli et al., 2014). At a certain stage, the polymer-rich phase is solidified, forming the solid matrix while the liquid phase is that of the membrane pores which are derived from the polymer-lean phase. The membranes can be made to be porous or nonporous by controlling the initial stages of precipitation (Mulder, 1996). Any polymer that is soluble in a solvent and can capable of being solidified in a non-solvent can be used to prepare membranes using this method. The phase separation can be accomplished in various ways such as non-solvent induced phase separation (NIPS), thermally induced phase separation (TIPS), evaporation-induced phase separation, and vapor-induced phase separation (Lalia et al., 2013). Two of the popular membrane preparation strategies, NIPS and TIPS, are the widely used methods for preparing anisotropic membranes commercially. 10.3.1.2 Non-solvent induced phase separation In non-solvent induced phase separation (NIPS), the polymer dope solution is first prepared from the selected precursors. This polymer solution is cast onto a support and then submerged in a non-solvent coagulation medium. The demixing process occurs because of the interchange of solvent and non-solvent. This causes rapid precipitation of the solution from the top of the surface which is exposed to the non-solvent at the bottom. The concentration of the polymer in the solution plays a significant role in determining the final morphology of the membrane for membrane preparation via NIPS. For instance, a high concentration of the polymer in the casting solution will result in membranes with small pore size and low porosity (Lalia et al., 2013). Besides, the choice of solvent and non-solvent also influence the morphology and properties of the membrane. Low polymer miscibility in a solvent forms dense membranes, while high miscibility of polymer in the solvent will yield more porous membranes. Additives are usually added to the casting solution to fasten the phase inversion process or to increase the solution viscosity. Moreover, the addition of additives in polymer dope changes the pore size and porosity of the casted membranes. Alcohols such as methanol, ethanol, and butanol are the common additives for gas separation membranes, while polyethylene glycol (PEG) and polyvinylpyrrolidone

266

Carbon Dioxide Capture and Conversion

(PVP) are the additives for water purification membranes (Aroon et al., 2010b). A co-solvent can be additionally added to the polymer dope to prevent macrovoid formation during rapid precipitation. 10.3.1.3 Thermally induced phase separation Thermally induced phase separation (TIPS) or thermal precipitation is another versatile method to prepare membranes with different morphologies. Fig. 10.2 summarizes the steps that are used to fabricate membranes via TIPS. Initially, a solvent, which has both high boiling point and low molecular weight, is chosen and then is melt-blended with the polymer to obtain a homogeneous solution (Lloyd et al., 1990). The solution is then cast onto suitable support into a chosen shape. The casted solution is cooled to a lower temperature to induce phase separation and form a polymer-rich phase that contains scattered pores filled with solvent. Since the cooling is steady and uniform, the membranes are usually isotropic with controlled pore sizes between 0.1 and 10 μm. After cooling, further solidification can be done via glass transition or crystallization (Ren and Wang, 2011). Finally, the porous membranes are formed by removing the solvent via solvent extraction. On the other hand, asymmetric membranes can be produced by having a polymer concentration gradient before inducing phase separation. Moreover, controlled evaporation of the solvent from the top side of the polymer/solvent above the binodial temperature led to the Polymer

High Temperature

Homogeneous Solution

Solvent

Casting Cooling Solidification

Solvent Removal

Figure 10.2 Process steps for thermally induced phase separation (TIPS).

Application of membrane technology for CO2 capture and separation

267

formation of a concentration gradient (Matsuyama et al., 1999). As the pore size is largely determined by the polymer concentration, successive cooling will result in membranes with small pores at the top side of the membrane and large pores at the bottom. Different than the NIPS, the casting solution used in TIPS is separated into two phases by removing the thermal energy. Although TIPS offers remarkable control of the pore size and minimal defect formation, it is important to note that TIPS is an energy-intensive process compared to NIPS (Figoli et al., 2014).

10.3.2 Preparation of inorganic membranes There are various techniques available for the fabrication of porous inorganic membranes. The selection of a suitable method usually depends on the membrane material and the desired pore size of the membrane. Different fabrication procedures are used to prepare the top layer and the support. The common methods for the preparation of inorganic membranes are slip casting, sol-gel process, CVD, and pyrolysis. 10.3.2.1 Slip casting Slip casting is the most widely used method to fabricate ceramic and metal oxide membranes because of the simplicity of the preparation method. Membranes prepared by slip casting have pore diameters of 0.01
10 μm (Baker, 2012). In this method, a colloidal suspension is first prepared by using a sol-gel process. To prepare membranes with small pores, it is necessary to prepare a stable dispersion of fine particles called slip. Then, a porous support is immersed into the slip and the suspension medium (e.g., alcohol/water mixture) is forced into the support pores. This happens due to the pressure drop induced by the capillary forces of the porous support (Burggraaf and Keizer, 1991). Eventually, a gel layer is formed from particle precipitation on the internal surface. The solid particles hold onto the interface and are concentrated at the pore entrance for the formation of a gel layer. Typically, relatively large particles are used in support or intermediate layer (Burggraaf and Keizer, 1991). 10.3.2.2 Sol-gel process The sol-gel process has received significant interest in the fabrication of finely porous membranes with pore diameters of 10
100 Å for gas separation (Baker, 2012). The sol-gel technique contains two main routes,

268

Carbon Dioxide Capture and Conversion

Alkoxides/ metal salts in alcohol

Water or acid (excess)

Colloidal route

Precipitation

Heat 80-95 oC Colloidal suspension

Polymeric route

Water (drop by drop)

Clear gel

Acid Coating

Drying

Sintering

Pure Inorganic Membrane

Figure 10.3 Sol-gel process for inorganic membranes.

and the steps involved in these routes are summarized in Fig. 10.3. In the colloidal route, the alkoxide dissolved in alcohol is hydrolyzed quickly by adding excess water or acid. The resulting precipitate is kept as a hot solution for a long duration to form a stable colloidal solution. This process is known as peptization (Baker, 2012). After cooling the colloidal solution, it is coated onto microporous support. To avoid cracking, the cast membrane should be dried properly. Finally, sintering is done at around 500°C
800°C. In the polymeric route, the hydrolysis of alkoxide in alcohol proceeds at a slower rate as the water is slowly added. The reaction of active hydroxyl groups on the alkoxides results in the formation of inorganic molecules. These molecules are then coated onto a support membrane before drying and sintered to produce a pure inorganic membrane. Tetraethoxysilane (TEOS) is the typical precursor for silica synthesis via the sol-gel process. Common materials such as alumina (Al2O3), silica (SiO2), zirconia (ZrO2), and titania (TiO2) are used in fabricating ceramic membranes (Erdem, 2017). Acidic catalysts may be used in the reactions to form finer particulates that will later help in producing a much finer microporous structure (Erdem, 2017). Moreover, the rates of the hydrolysis and the condensation reactions determine the particulate size in the sol. It is important to control the particulate size in the sol as the size of the particulate affects

Application of membrane technology for CO2 capture and separation

269

the porosity and the pore size of the membrane. Additives such as acetylacetone can be used to prevent the formation of large particulates in the sol. In addition, adding a binder to the coating solution alleviates the cracking. 10.3.2.3 Chemical vapor deposition A thin layer of silica is deposited on porous ceramic support using CVD. The silica layer is formed due to the reaction between a silica precursor and reactive agents such as O2, water, or ozone. The commonly used ceramic supports are alumina and Vycor (Kayvani Fard et al., 2018). 10.3.2.4 Pyrolysis Membranes with an ultra-fine pore diameter of 2.5 nm can be prepared by pyrolysis of polymeric precursors (Baker, 2012). Through proper control of pyrolysis conditions, molecular sieve carbon or silica membranes can be made.

10.4 Polymeric membranes 10.4.1 Polymer blends membranes Polymeric membranes have been extensively studied for gas separation as they are simple to fabricate and easy to scale up. However, the challenges in polymeric membranes include the upper bound relationship between permeability and selectivity, and CO2-induced plasticization when operating at elevated and physical aging. To compete with existing membrane materials, the production cost of novel polymeric membranes should be economically feasible. Over the decades, various modifications have been proposed to overcome the main challenge of trade-off relationship through polymer blends (Mannan et al., 2013; Paul and Newman, 1978; Yong and Zhang, 2021), MMMs (Chung et al., 2006; Denny et al., 2016; Galizia et al., 2017), and facilitated transport membranes (Hussain and Hägg, 2010; Liao et al., 2014). Conventional polymers including polyethersulfone (PES or PESU), PSf, Matrimid, and polybenzimidazole (PBI) have been generally used in gas separation. Novel polymers such as poly (trimethylsilylpropyne) (PTMSP), thermally rearranged (TR) polymers based on polybenzoxazoles (PBOs), polymers of intrinsic microporosity (PIMs), and aromatic polymers containing iptycene units have gained significant interest for gas separation, especially for CO2 separation.

270

Carbon Dioxide Capture and Conversion

Among these polymers, PIMs and TR polymeric membranes demonstrated CO2/CH4 separation surpassing the Robeson upper bound. Other than synthesizing new polymers, polymer blends are one of the attractive ways because of being cost- and time-effective and they possess a synergistic way to obtain membranes with superior properties that are not present in the individual polymer (Yong et al., 2012). Fig. 10.4 illustrates the synergistic properties of polymer blends to improve permeability and selectivity. The phase behavior of polymer blends plays a crucial role in membrane gas separation, where it can be grouped into miscible, immiscible, and partially miscible blends. A homogeneous single phase is obtained in a miscible blend as both the polymers dissolve completely at the molecular level and only one glass transition temperature (Tg) appears, while a heterogeneous phase is observed in an immiscible blend because the polymers do not dissolve properly in each other. Hence, two respective Tgs are observed in immiscible blends. Moreover, a heterogeneous phase also exists in a partially miscible blend as the polymers are only dissolved partially in one another. These polymers show uniform physical properties at the macroscopic level due to the strong interactions between the polymers (Qin, 2016). Partially immiscible blends are also known as isotropic

Figure 10.4 Schematic overview of polymer blends.

Application of membrane technology for CO2 capture and separation

271

heterogeneous polymers as the composition of the blended phases is different from that of the pristine individual polymers. The miscibility of polymer blends is promoted through hydrogen bonding (Musto et al., 1991; Shogbon et al., 2006; Wang et al., 2007), charge transfer complexes (CTCs) (Butnaru et al., 2020; Hasegawa et al., 1989; Hasegawa et al., 1991; Yong and Chung, 2015; Yong et al., 2012), and dipole
dipole forces between polymers (Walsh and Rostami, 1985). By adding the permeability of each component semi-logarithmically, the permeability of the polymer blend is obtained. lnPb

1 lnP1

2 lnP2

(10.7)

where P1 and P2 are permeabilities of the individual components, while Pb is the permeability of the polymer blend. 1 and 2 are the components’ volume fractions. The polymer blend selectivity can be eventually obtained from the following equation:       PA PA PA ln (10.8) 1 ln 2 ln PB PB 1 PB 2 Besides, the Fox equation (Fox, 1952) has been used in predicting the Tg of polymer blends:     1 w1 w2 (10.9) Tg Tg1 Tg2 where w1 and w2 are the weight fractions of the individual components in the polymer blends, respectively, and Tg1 and Tg2 are the glass transition temperatures of individual components, accordingly. Among the polymeric materials, polyimide, PBI, and PIMs have been widely studied in polymer blends especially in applications such as CO2 capture, pervaporation, and fuel cell application (Yong and Zhang, 2021). The intrinsic high permeability, high selectivity, and superior chemical, thermal or mechanical stabilities in these materials allow them to be one of the promising candidates to blend with other materials. In recent years, the blends of polyimide such as Matrimid 5218 (Bos et al., 2001; Castro-Muñoz et al., 2019; Yong and Chung, 2015; Yong et al., 2014; Yong et al., 2012), polyetherimide (Ultem) (Musto et al., 1991), polyetherimide sulfone (Extem) (Mazinani et al., 2017; Mazinani et al., 2018), Torlon 4000 T (polyamide-imide) (Wang et al., 2007), and BTDATDI/MDI (P84) (Bos et al., 2001; Wang et al., 2007) with PES

272

Carbon Dioxide Capture and Conversion

(Han et al., 2010; Liang et al., 1992), sulfonated poly(ether ether ketone) (SPEEK) (Khan et al., 2011), and fluorinated SPEEK (F-SPEEK) (Asghar et al., 2018), PEG (Loloei et al., 2015), PBI (Wang et al., 2007), and PSf (Bos et al., 2001; Kapantaidakis et al., 1999; Rafiq et al., 2011a,b) have been investigated. Fig. 10.5 shows the state-of-the-art blend membranes for CO2/N2 and CO2/CH4 separation using polyimide as one of the components. Compared to the pristine material, the blends show a significant improvement in terms of permeability and selectivity. In addition, the blends of PBI with Matrimid (Chung et al., 2006; Grobelny et al., 1990; Hosseini et al., 2008), Ultem (Musto et al., 1991), and Torlon (Wang et al., 2007) showed single Tg, which signify their miscibility at the molecular scale. Most of the PBI based blends such as PBI/ Matrimid (Hosseini and Chung, 2009; Hosseini et al., 2008), PBI/Torlon (Hosseini and Chung, 2009), and PBI/P84 (Hosseini and Chung, 2009) possessed high H2/N2, O2/N2, CO2/CH4, and H2/CO2 selectivity (Hosseini and Chung, 2009) while PBI/polyaniline (PANI) blend membranes showed superior CO2/CH4 and CO2/N2 separation (Giel et al., 2016). Besides, the recently developed PBI/sulfonated polyphenylsulfone (sPPSU) hollow fiber membranes exhibited the potential for H2/CO2 separation (Naderi et al., 2019). PIMs with a large surface area that yields superior permeability have been widely incorporated in the polymer blend membranes (Kim and Lee, 2015; McKeown and Budd, 2006). The PIM-1/Matrimid (Liu and Wilson, 2008; Yong et al., 2012), PIM-1/Ultem (Hao et al., 2014; Liu and Wilson, 2008), PIM-1/4,40 -(hexafluoroisopropylidene)diphthalic

Figure 10.5 Polymer blend membranes based on polyimide for (A) CO2/N2 and (B) CO2/CH4 separation.

Application of membrane technology for CO2 capture and separation

273

dianhydride-m-phenylenediamine (6FDA-m-PDA) (Liu and Wilson, 2008), PIM-1/PEG (Wu et al., 2015), PIM-1/sPPSU (Yong et al., 2016), PIM-1/Tröger’s Base (TB) (Zhao et al., 2018), PIM-ethanoanthracene EA(H2)-TB/Matrimid (Esposito et al., 2019), PIM-B/PEI (García et al., 2017), PIM-1/1-hexyl-3-methyl-imidazolium bis (trifluoromethylsulphonyl) imide [C6mim][Tf2N] (Halder et al., 2017), cPIM-1/Torlon (Yong et al., 2014), cPIM-1/P84 (Salehian et al., 2016), and cPIM-1/Matrimid (Yong and Chung, 2015) blend membranes demonstrated a high CO2 permeability of 2.18
6650 Barrer with CO2/N2 selectivity of 12.9
30.0 and CO2/CH4 selectivity of 14.0
48.7 depending on the loading of PIMs. The PIM-1 blend membranes demonstrated a high potential for CO2/N2 and CO2/CH4 separation.

10.4.2 Mixed matrix membranes MMMs are one of the emerging and promising modification strategies since MMMs provide synergistic properties of superior selectivity of the inorganic membranes and the ease of fabricability of the polymeric membranes (Aroon et al., 2010a; Chung et al., 2007). MMMs consist of inorganic or organic fillers as a dispersed phase in a continuous polymer matrix. The inorganic particles can be either porous or nonporous. Maxwell model is widely applied to estimate the transport properties of gases in MMMs (Maxwell, 1954):  Pd 2Pc 2 ðPc Pd Þ Peff Pc (10.10) Pd 2Pc ðPc Pd Þ where Peff is the effective permeability of the MMMs, Pc and Pd are the permeabilities of continuous and dispersed phases, and is the dispersed phase volume fraction. The methods used to fabricate the MMMs are very similar to polymeric membranes. In particular, there are three possible methods to prepare the homogeneous solution (Lin et al., 2018) as follows: 1. Inorganic or organic particles are added into the solvent and stirred for a stipulated time, then the polymer is added. 2. The polymer solution is first made by dissolving the polymer into the solvent. The inorganic or organic fillers are subsequently added to the solution. 3. Polymer is dissolved into the solvent, and the inorganic or inorganic particles are suspended into the solvent separately in two bottles before mixing them.

274

Carbon Dioxide Capture and Conversion

After preparing the homogeneous solution, the solution is cast onto a flat plate. Subsequently, the solvent is allowed to evaporate from the casting solution. Finally, the resultant membrane is annealed at an elevated temperature to remove the remaining solvent. The common inorganic fillers are CMS, zeolites, and silica (Chung et al., 2007). Among these inorganic fillers, zeolites are one of the commonly used fillers in MMMs for CO2/CH4 separation because of their peculiar molecular sieving characteristics along with excellent chemical, mechanical, and thermal stability. The MMMs consisting of zeolites include cross-linkable polyimide (PDMC)/SSZ-13 (Ward and Koros, 2011), Pebax-1657/zeolite 4 A (Murali et al., 2014), PVAc/zeolite 4 A (Adams et al., 2011), Matrimid/ ZSM-5 (Musselman et al., 2009; Zhang et al., 2008), Ultem 1000/HSSZ13 (Husain and Koros, 2007), and Pebax 1074/SAPO-34 (Rabiee et al., 2015). All of these membranes showed impressive CO2/CH4 selectivities in the range of 26.4 to 67.4 depending on the zeolite loading. In recent years, new types of sieve materials such as polyhedral oligomeric silsesquioxane (POSS), graphene oxides (GOs), metal-organic frameworks (MOFs), and carbon nanotubes (CNTs) have been widely studied in MMMs (Furukawa et al., 2013). MOFs made of metal ions and coordinatively bridged by organic ligands feature high porosity, large pore volume, and selective adsorption of gases. The chemical functionalities in MOFs allow them to have better compatibility and dispersity in the polymer. Compared to zeolites, MOFs have a greater influence on the gas transport properties of MMMs in a given loading owing to the higher pore volumes in MOFs (Goh et al., 2022). The MOFs such as zeolitic imidazole framework-8 (ZIF-8) (Basu et al., 2011; Venna, 2010; Zornoza et al., 2011), ZIF-90 (Atci and Keskin, 2012; Bae et al., 2010), Cu3(BTC)2 (Basu et al., 2011; Car et al., 2006; Guo et al., 2009), MIL-53 (Car et al., 2006), MIL-101 (Jeazet et al., 2013), and ZIF-71 (Japip et al., 2014; Japip et al., 2016) are commonly used for CO2/CH4 and CO2/N2 separation, owing to their large surface area and discrimination of gases.

10.5 Inorganic membranes 10.5.1 Carbon molecular sieve membranes CMS membranes are porous solid with micropores or apertures that are similar to the dimensions of diffusing gases. The tiny pores can repulse large gas molecules while letting the small ones pass through (Jones and Koros, 1994). CMS membranes are promising for CO2 separation because

Application of membrane technology for CO2 capture and separation

275

they can achieve a high selectivity without compromising the gas permeability, which overcomes the trade-off between permeability and selectivity (Hosseini and Chung, 2009; Jones and Koros, 1994; Rungta et al., 2017). In addition, CMS membranes are known to operate under adverse and rigorous conditions such as a high temperature up to 1400°C (Bhuwania et al., 2014; Vu et al., 2003) and strongly acidic environments (Jones and Koros, 1994; Tin et al., 2004). The pyrolysis method is a common method for the preparation of CMS membranes. It mainly involves heating/carbonizing the polymeric precursor or the base membrane at different temperatures and environments (Baker, 2012; Saufi and Ismail, 2004). The representative schematic structures of the CMS membranes made by pyrolysis are described in Fig. 10.6. The CMS membranes are amorphous, which mainly consist of chars. The slit-like pore structure is formed due to the imperfect packing of the carbonized materials (see Fig. 10.6B). The idealized slit-like structure possesses a bimodal pore size distribution (see Fig. 10.6C), where the pore size of the micropores is between 7 and 20 Å and the pore size of the ultramicropores is 7 Å (Bhuwania et al., 2014). This unique pore structure enables the CMS membrane to molecularly sieve the gases according to their sizes, resulting in membranes with high gas selectivity and permeability (Hosseini and Chung, 2009; Jones and Koros, 1994; Rungta et al., 2017; Tin et al., 2004). The pyrolysis method has been widely studied because it offers several controllable parameters to tailor the properties and performances of the CMS membranes (Baker, 2012; Kiyono et al., 2010; Saufi and Ismail, 2004; Steel and Koros, 2005; Tin et al., 2004). The chemical structure and microstructure of the precursor polymer, the pyrolysis process parameters, and post-treatment conditions are the important factors that have a significant influence on the gas transport properties of the resultant CMS membrane (Hosseini and Chung, 2009). To produce a highperformance CMS membrane, a proper selection of polymer precursor material is the utmost critical because of the structure and chemical composition of the precursor affecting the properties of CMS membrane (Tin et al., 2004). Besides the selection of precursor materials, the properties of the CMS membrane could be tuned by performing pretreatment on the precursor membranes and post-treatments on the CMS membranes (Saufi and Ismail, 2004). The pretreatment methods include oxidation, stretching, and chemical treatments. The post-treatment methods include post-oxidation, heat

276

Carbon Dioxide Capture and Conversion

Figure 10.6 Illustrations of structural properties of the CMS membrane. (A) Structure of pyrolytic carbon material, (B) idealized pore structure of CMS membrane, and (C) idealized bimodal pore size distribution of CMS membrane.




soaking, coating, and CVD. In the CVD method, the pyrolytic carbon is deposited on a microporous carbon substrate that has a large mean pore mouth. Subsequently, the large pore mouth of the substrate is reduced to the desired sizes that allow size sieving or improve selectivity (Carrott et al., 2006). To fabricate an asymmetric hollow fiber membrane with high selectivity, the selective layer of the membrane should be ultrathin with defect-free or minimum defect (Henis and Tripodi, 1981; Liang et al., 2019). Typically, the asymmetric CMS membrane is fabricated as hollow fiber configurations (Sanyal et al., 2018).

10.5.2 Ceramic membranes Ceramic membranes have been widely studied for gas separations due to their excellent chemical and thermal stabilities under harsh conditions (Baker, 2012; Tennison, 1998; Yeo et al., 2012). They are usually made from silicon aluminum (Al2O3), titanium (TiO2), zirconium dioxide (ZrO2), and silicon dioxide (SiO2) (Baker, 2012; Yeo et al., 2012).

Application of membrane technology for CO2 capture and separation

277

Conventional methods to prepare ceramic membranes are the slip casting and sol-gel methods, in which the ceramic materials are prepared in the form of a membrane, followed by drying and sintering at high temperatures (Baker, 2012). Ceramic membranes made by the slip casting process usually include microfiltration (MF) and ultrafiltration (UF) with pore sizes of 0.01
10 μm. Such porous ceramic membranes can be used as substrates for post-treatments or modifications to have superior gas separation performances (Baker, 2012; Pan et al., 2012; Yeo et al., 2012). Ceramic membranes produced by the sol-gel methods possess relatively fine pores that are in the range of 1
10 nm and are attractive in making defect-free membranes for gas separation applications (Baker, 2012). A typical ceramic membrane for gas separation consists of three layers: macroporous support layer, mesoporous intermediate layer, and microporous top skin layer. Among these three layers, the skin layer is the selective layer that contains pore sizes smaller than 1 nm for separating different gases, while the other two layers act as mechanical support (Ding et al., 2001; Yeo et al., 2012). Ceramic membranes made from alumina (i.e., alumina ceramic membrane) are not commonly used for CO2 separation because of their low selectivity (Yeo et al., 2012). The low selectivity in the alumina ceramic membrane is owing to its mesoporous structure where gas transports through the Knudsen diffusion mechanism. Nevertheless, alumina ceramic membrane is suitable as membrane support because it has a low-resistant porous structure and excellent chemical and thermal stability at high temperature (e.g., 1000°C) (Lu et al., 2004; Yeo et al., 2012). The formation of a thin selective ceramic layer on the porous substrate through slip casting, tape casting, and coating, in which a slurry comprised of ceramic particles and additives is deposited onto the surface of the substrate, followed by heat treatment at high temperatures (Li, 2007; Wu, 2019). Porous ceramic membranes have been widely used as supports to produce thin composite ceramic membranes for gas separations (Athayde et al., 2016; Huang et al., 2017; Pan et al., 2012; Tennison, 1998; Yeo et al., 2012; Zhang et al., 2013). A thin silica ceramic layer (e.g., 50
100 nm) is deposited on top of a porous alumina ceramic support using the sol-gel technique, which demonstrates a high potential for CO2 separation (Yeo et al., 2012). Huang et al. employed a GO thin layer on an alumina ceramic hollow fiber membrane by a vacuum suction method to produce GO/ceramic composite hollow fiber membrane for CO2 separation (Huang et al., 2017). The as-produced GO/ceramic membrane

278

Carbon Dioxide Capture and Conversion

shows H2 permeance of about 300 GPU and H2/CO2 selectivity of 10 under mixed gas testing conditions. Pan et al. successfully prepared ZIF-8 on yttria-stabilized zirconia (YSZ) ceramic hollow fiber support by using an in-situ seeded grown method for gas separation (Pan et al., 2012). Fig. 10.7 shows the scanning electron microscope (SEM) images and X-ray diffraction (XRD) spectra of the YSZ membrane support and ZIF8/YSZ membrane. As shown in Fig. 10.7A
C, the cross-section of the YSZ ceramic support is macroporous, while the outer surface is denser than the cross-section. Fig. 10.7D and E show that the ZIF-8 layer is dense and thin. The thickness of the ZIF-8 layer grown on the support is about 2 μm, while the presence of the ZIF-8 layer on the support is evidenced by the XRD patterns as described in Fig. 10.7E. The CO2 permeance of the ZIF-8/YSZ membrane is about 1200 GPU, and the corresponding CO2/N2 and H2/CO2 selectivity are 2.8 and 3.8, respectively. Although the ZIF-8/YSZ composite membrane shows poor selectivity for CO2 separation, it has excellent performances for H2 separation from other hydrocarbon gases.

Figure 10.7 SEM images of (A) YSZ ceramic hollow fiber support, (B) an enlarged cross-section of the YSZ ceramic hollow fiber, (C) outer surface of the YSZ ceramic hollow fiber, (D) top view, and (E) cross-section view of the as-synthesized ZIF-8 membrane, (F) XRD patterns of the support and ZIF-8/support membranes. The star symbols in (F) indicate peaks from the YSZ ceramic hollow fiber support.







Application of membrane technology for CO2 capture and separation

279

10.5.3 Zeolite membranes Zeolites are inorganic crystalline aluminosilicate with well-defined pores at molecular dimensions (Kosinov et al., 2016; Lin and Duke, 2013; Tomita et al., 2007; Yeo et al., 2012). Zeolite membranes are attractive for CO2 and other gas separations because of their uniform pore structures, superior stabilities at aggressive conditions such as high temperature, high pressure, and harsh chemical conditions (Kosinov et al., 2016; Krishna and van Baten, 2010). Typically, a zeolite membrane comprises a selective zeolitic layer or film and a porous inorganic support (Kosinov et al., 2016; Tomita et al., 2007; Yeo et al., 2012). The gas separation mechanisms of zeolite membranes include (Kosinov et al., 2016; Yeo et al., 2012) the following: 1. Adsorption selectivity, which is the dominant mechanism at low to moderate temperatures (e.g., 100°C
200°C), 2. Diffusion selectivity, which increases with temperature 3. Size exclusion (molecular sieving), which is a unique class of diffusion selectivity for specific gas pairs (e.g., H2/i-butane). Different from the other types of membranes, zeolite membranes can separate gases based on the properties of gases such as shape, size, polarity, and affinity (Yeo et al., 2012). The gas separation performances of zeolite membranes are dominated by several factors such as gas properties (e.g., size, polarity, and affinity), the topology and chemical composition of zeolite, and the morphology of the support (Kosinov et al., 2016; Li et al., 2015; Zhang et al., 2013). The in-situ synthesis and secondary growth are two common methods to produce zeolite membranes. In the in-situ synthesis method, the zeolite crystals inter-grow on the surface of the porous support using an autoclave vessel (Geus et al., 1992; Kosinov et al., 2016; Suzuki, 1987). In the secondary growth method, a thin layer of the designated zeolite nanocrystals is first deposited on the surface of the support, then followed by a second layer of zeolite polycrystalline deposited on top of the first layer through a hydrothermal secondary crystallization. Fig. 10.8 compares the gas separation performances of the zeolite/ microporous structures studied by the simulation data (Krishna and van Baten, 2010). As shown in Fig. 10.8A and B, these zeolite structures that are located above the Robeson upper bound line are the potential candidates for CO2 separation from flue gas (e.g., CO2/N2), natural gas, and biogas (e.g., CO2/CH4). Some of the predicted separation performances

280

Carbon Dioxide Capture and Conversion

of zeolites (e.g., MFI and NaY) are in good agreement with the experimental results (Krishna and van Baten, 2010). Among these zeolites, NaX and NaY appear to be promising candidates for CO2 separations from the pre- and post-combustion processes (e.g., natural/biogas and flue gas). As presented in Fig. 10.8C, the CO2/H2 selectivity is lowered by a factor of 3
10 as compared to CO2/N2 and CO2/CH4 selectivity. Zeolites are generally not favorable for the CO2/H2 (e.g., syngas) separation, because the molecular size of H2 is much smaller than N2 and CH4 (Krishna, 2009; Krishna and van Baten, 2010). The characteristics of porous support of the zeolite membrane are important to produce promising zeolite membranes. The preferred characteristics of the supports include the following: 1. Rigid and strong structure. 2. Stability in hydrothermal and alkaline solutions. 3. Low gas transport resistance. 4. Smooth surface. 5. Compatibility/affinity between the zeolite layer and support. The most common porous supports are ceramic materials (e.g., alumina, titania, silica) (Kosinov et al., 2016). In addition, stainless steel, carbon, and zeolite can also be used as supports (Kosinov et al., 2016). Similar to the other gas separation membranes, an ideal and productive zeolite membrane should have a thin defect-free zeolite layer on top of a robust and porous substrate (Yeo et al., 2012). Nevertheless, the limitations in zeolite membranes are to replicate the production of thin (e.g., 1.5 μm) and oriented

CO2/N2 selecvity (-)

CO2 permeability (104 Barrer)

(C) CO2/H2 selecvity (-)

(B) CO2/CH4 selecvity (-)

(A)

CO2 permeability (104 Barrer)

CO2 permeability (104 Barrer)

Figure 10.8 The gas separation performance of the zeolite/microporous structures based on the computer-simulated results. Robeson plot of (A) CO2/N2, (B) CO2/CH4, and (C) CO2/H2 separation. The simulation is studied at a feed fugacity of 1 MPa and temperature of 300 K. Note that the -axis is expressed in 104 Barrer.


Application of membrane technology for CO2 capture and separation

281

zeolite layer without or with minimum defects (Li et al., 2015; Yeo et al., 2012). Similar to the other inorganic membranes, zeolite membranes are costly (Kosinov et al., 2016; Lin and Duke, 2013).

10.6 Conclusions and perspectives The membrane-based CO2 separation technology emerged as a promising alternative solution to address the CO2-related issues. Given the huge amount of CO2 sources (e.g., flue gas, natural gas syngas, and biogas) that are in a magnitude of gigatonnes, high-performance and productive membranes are highly demanded. The development of suitable membrane materials for targeted applications is fundamentally important. On the other hand, the transformation of the materials into productive membranes, which have a very thin selective layer and robust porous support, is equally crucial. Membrane fabrication techniques such as flat sheet membranes and hollow fiber membranes from both polymeric and inorganic membranes help to develop materials in actual applications. Although the polymeric membranes are dominant in the current CO2 separation industries, their intrinsic properties such as the permeabilityselectivity trade-off and low thermal stability limited their applications. The bulk gas separation market is dominated by a small number of commercial polymers. The concerns that need to be addressed are as follows: 1. Reduce the production cost. 2. Improve permeability and selectivity. 3. Overcome CO2-induced plasticization issues. 4. Retard aging of polymeric membranes. The inorganic membranes including CMS membranes, ceramic membranes, and zeolite membranes are capable of overcoming the limitations of polymeric membranes. Inorganic membranes are especially suitable for CO2 separation at high temperatures (e.g., up to 1400°C) and high pressures. The separation performances, thermal and chemical stability of the inorganic membranes are generally superior to the polymeric membranes; however, the stability and production cost issues are major obstacles for commercialization. Three practical issues are needed to be addressed for the inorganic membranes which include the following: 1. Fabricate thin selective inorganic layer on top of the porous substrate in a reproducible way. 2. Reduce the cost of the inorganic membranes. 3. Increase the membrane stability towards harsh impurities.

282

Carbon Dioxide Capture and Conversion

Although it is challenging to fabricate inorganic hollow fiber membranes for gas separation, it is worthy to develop the membranes in the hollow fiber configuration. Besides the CMS membranes, ceramic membranes and zeolite membranes, other membrane materials such as MOFs are promising candidates for the fabrication of high-performance composite membranes for CO2 capture and separation. In addition, long-term stability studies similar to the industrial conditions (e.g., high temperature and pressure, presence of harsh impurities) are necessary to evaluate performances of membranes before pilot and large-scale CO2 separation applications.

References Abhisha, V.S., Swapna, V.P., Stephen, R., 2018. Chapter 18
Modern trends and applications of gas transport through various polymers. In: Thomas, S., Wilson, R., Anil Kumar, S., George, S.C. (Eds.), Transport Properties of Polymeric Membranes. Elsevier, pp. 363
389. Adams, R.T., Lee, J.S., Bae, T.-H., Ward, J.K., Johnson, J., Jones, C.W., et al., 2011. CO2-CH4 permeation in high zeolite 4A loading mixed matrix membranes. Journal of Membrane Science 367, 197
203. Adewole, J.K., Ahmad, A.L., Ismail, S., Leo, C.P., 2013. Current challenges in membrane separation of CO2 from natural gas: a review. International Journal of Greenhouse Gas Control 17, 46
65. Aroon, M.A., Ismail, A.F., Matsuura, T., Montazer-Rahmati, M.M., 2010a. Performance studies of mixed matrix membranes for gas separation: a review. Separation and Purification Technology 75, 229
242. Aroon, M.A., Ismail, A.F., Montazer-Rahmati, M.M., Matsuura, T., 2010b. Morphology and permeation properties of polysulfone membranes for gas separation: effects of non-solvent additives and co-solvent. Separation and Purification Technology 72, 194
202. Asghar, H., Ilyas, A., Tahir, Z., Li, X., Khan, A.L., 2018. Fluorinated and sulfonated poly (ether ether ketone) and matrimid blend membranes for CO2 separation. Separation and Purification Technology 203, 233
241. Atci, E., Keskin, S., 2012. Atomically detailed models for transport of gas mixtures in ZIF membranes and ZIF/polymer composite membranes. Industrial & Engineering Chemistry Research 51, 3091
3100. Athayde, D.D., Souza, D.F., Silva, A.M.A., Vasconcelos, D., Nunes, E.H.M., Diniz da Costa, J.C., et al., 2016. Review of perovskite ceramic synthesis and membrane preparation methods. Ceramics International 42, 6555
6571. Bae, T.H., Lee, J.S., Qiu, W., Koros, W.J., Jones, C.W., Nair, S., 2010. A high-performance gas-separation membrane containing submicrometer-sized metal-organic framework crystals. Angewandte Chemie 122, 10059
10062. Baker, R.W., 2002. Future directions of membrane gas separation technology. Industrial & Engineering Chemistry Research 41, 1393
1411. Baker, R.W., 2012. Membrane Technology and Applications, third ed. John Wiley & Sons. Baker, R.W., Lokhandwala, K., 2008. Natural gas processing with membranes: an overview. Industrial & Engineering Chemistry Research 47, 2109
2121.

Application of membrane technology for CO2 capture and separation

283

Basu, S., Cano-Odena, A., Vankelecom, I.F., 2011. MOF-containing mixed-matrix membranes for CO2/CH4 and CO2/N2 binary gas mixture separations. Separation and Purification Technology 81, 31
40. Bhuwania, N., Labreche, Y., Achoundong, C.S.K., Baltazar, J., Burgess, S.K., Karwa, S., et al., 2014. Engineering substructure morphology of asymmetric carbon molecular sieve hollow fiber membranes. Carbon 76, 417
434. Bos, A., Pünt, I., Strathmann, H., Wessling, M., 2001. Suppression of gas separation membrane plasticization by homogeneous polymer blending. AIChE Journal 47, 1088
1093. Bos, A., Punt, I.G.M., Wessling, M., Strathmann, H., 1999. CO2-induced plasticization phenomena in glassy polymers. Journal of Membrane Science 155, 67
78. Burggraaf, A., Keizer, K., 1991. Synthesis of inorganic membranes. Inorganic Membranes Synthesis, Characteristics and Applications. Springer, pp. 10
63. Butnaru, I., Constantin, C.-P., Asandulesa, M., Woli´nska-Grabczyk, A., Jankowski, A., Szeluga, U., et al., 2020. Insights into molecular engineering of membranes based on fluorinated polyimide-polyamide miscible blends which do not obey the trade-off rule. Separation and Purification Technology 233, 116031. Car, A., Stropnik, C., Peinemann, K.-V., 2006. Hybrid membrane materials with different metal-organic frameworks (MOFs) for gas separation. Desalination (Amst.) 200, 424
426. Carrott, P.J.M., Cansado, I.P.P., Carrott, M.M.L.R., 2006. Carbon molecular sieves from PET for separations involving CH4, CO2, O2 and N2. Applied Surface Science 252, 5948
5952. Castro-Muñoz, R., Fíla, V., Ahmad, M.Z., 2019. Enhancing the CO2 separation performance of Matrimid 5218 membranes for CO2/CH4 binary mixtures. Chemical Engineering & Technology 42, 645
654. Chen, B., Yang, Z., Zhu, Y., Xia, Y., 2014. Zeolitic imidazolate framework materials: recent progress in synthesis and applications. Journal of Materials Chemistry A 2, 16811
16831. Chung, T.-S., Guo, W.F., Liu, Y., 2006. Enhanced matrimid membranes for pervaporation by homogenous blends with polybenzimidazole (PBI). Journal of Membrane Science 271, 221
231. Chung, T.-S., Jiang, L.Y., Li, Y., Kulprathipanja, S., 2007. Mixed matrix membranes (MMMs) comprising organic polymers with dispersed inorganic fillers for gas separation. Progress in Polymer Science 32, 483
507. Comesaña-Gándara, B., Chen, J., Bezzu, C.G., Carta, M., Rose, I., Ferrari, M.-C., et al., 2019. Redefining the Robeson upper bounds for CO2/CH4 and CO2/N2 separations using a series of ultrapermeable benzotriptycene-based polymers of intrinsic microporosity. Energy & Environmental Science 12, 2733
2740. Denny, M.S., Moreton, J.C., Benz, L., Cohen, S.M., 2016. Metal
organic frameworks for membrane-based separations. Nature Reviews Materials 1, 1
17. Ding, Z., Kloprogge, J.T., Frost, R.L., 2001. Porous clays and pillared clays-based catalysts. Part 2: a review of the catalytic and molecular sieve applications. Journal of Porous Materials 8, 273
293. Erdem, ˙I., 2017. Sol-gel applications for ceramic membrane preparation. AIP Conference Proceedings. AIP Publishing LLC, p. 020011. Esposito, E., Mazzei, I., Monteleone, M., Fuoco, A., Carta, M., McKeown, N.B., et al., 2019. Highly permeable Matrimid /PIM-EA(H2)-TB blend membrane for gas separation. Polymers 11, 46. Figoli, A., Marino, T., Simone, S., Di Nicolo, E., Li, X.-M., He, T., et al., 2014. Towards non-toxic solvents for membrane preparation: a review. Green Chemistry 16, 4034
4059.

284

Carbon Dioxide Capture and Conversion

Fox, T.G., 1952. Influence of diluent and of copolymer composition on the glass temperature of a polymer system. Bulletin of the American Physical Society 1, 123. Fu, S., Sanders, E.S., Kulkarni, S.S., Koros, W.J., 2015. Carbon molecular sieve membrane structure-property relationships for four novel 6FDA based polyimide precursors. Journal of Membrane Science 487, 60
73. Furukawa, H., Cordova, K.E., O’Keeffe, M., Yaghi, O.M., 2013. The chemistry and applications of metal-organic frameworks. Science 341, 1230444. Galizia, M., Chi, W.S., Smith, Z.P., Merkel, T.C., Baker, R.W., Freeman, B.D., 2017. 50th anniversary perspective: polymers and mixed matrix membranes for gas and vapor separation: a review and prospective opportunities. Macromolecules 50, 7809
7843. García, M.G., Marchese, J., Ochoa, N.A., 2017. Improved gas selectivity of polyetherimide membrane by the incorporation of PIM polyimide phase. Journal of Applied Polymer Science 134, 44682. Geus, E.R., den Exter, M.J., van Bekkum, H., 1992. Synthesis and characterization of zeolite (MFI) membranes on porous ceramic supports. Journal of the Chemical Society, Faraday Transactions 88, 3101
3109. ˇ Giel, V., Kredatusová, J., Trchová, M., Brus, J., Zitka, J., Peter, J., 2016. Polyaniline/polybenzimidazole blends: characterisation of its physico-chemical properties and gas separation behaviour. European Polymer Journal 77, 98
113. Goh, S.H., Lau, H.S., Yong, W.F., 2022. Metal-organic frameworks (MOFs)-based mixed matrix membranes (MMMs) for gas separation: A review on advanced materials in harsh environment applications. Small 2107536. Grobelny, J., Rice, D.M., Karasz, F.E., Macknight, W., 1990. High-resolution solid-state carbon-13 nuclear magnetic resonance study of polybenzimidazole/polyimide blends. Macromolecules 23, 2139
2144. Guo, H., Zhu, G., Hewitt, I.J., Qiu, S., 2009. “Twin copper source” growth of metalorganic framework membrane: Cu3(BTC)2 with high permeability and selectivity for recycling H2. Journal of the American Chemical Society 131, 1646
1647. Halder, K., Khan, M.M., Grünauer, J., Shishatskiy, S., Abetz, C., Filiz, V., et al., 2017. Blend membranes of ionic liquid and polymers of intrinsic microporosity with improved gas separation characteristics. Journal of Membrane Science 539, 368
382. Han, J., Lee, W., Choi, J.M., Patel, R., Min, B.-R., 2010. Characterization of polyethersulfone/polyimide blend membranes prepared by a dry/wet phase inversion: precipitation kinetics, morphology and gas separation. Journal of Membrane Science 351, 141
148. Hao, L., Li, P., Chung, T.-S., 2014. PIM-1 as an organic filler to enhance the gas separation performance of Ultem polyetherimide. Journal of Membrane Science 453, 614
623. Hasegawa, M., Kochi, M., Mita, I., Yokota, R., 1989. Molecular aggregation and fluorescence spectra of aromatic polyimides. European Polymer Journal 25, 349
354. Hasegawa, M., Mita, I., Kochi, M., Yokota, R., 1991. Miscibility of polyimide/polyimide blends and charge-transfer fluorescence spectra. Polymer 32, 3225
3232. Hashim, S.M., Mohamed, A.R., Bhatia, S., 2010. Current status of ceramic-based membranes for oxygen separation from air. Advances in Colloid and Interface Science 160, 88
100. Henis, J.M.S., Tripodi, M.K., 1981. Composite hollow fiber membranes for gas separation: the resistance model approach. Journal of Membrane Science 8, 233
246. Henis, J.M.S., Tripodi, M.K., 1983. The developing technology of gas separating membranes. Science 220, 11
17. Hosseini, S.S., Chung, T.S., 2009. Carbon membranes from blends of PBI and polyimides for N2/CH4 and CO2/CH4 separation and hydrogen purification. Journal of Membrane Science 328, 174
185.

Application of membrane technology for CO2 capture and separation

285

Hosseini, S.S., Teoh, M.M., Chung, T.S., 2008. Hydrogen separation and purification in membranes of miscible polymer blends with interpenetration networks. Polymer 49, 1594
1603. Huang, K., Yuan, J., Shen, G., Liu, G., Jin, W., 2017. Graphene oxide membranes supported on the ceramic hollow fibre for efficient H2 recovery. Chinese Journal of Chemical Engineering 25, 752
759. Husain, S., Koros, W.J., 2007. Mixed matrix hollow fiber membranes made with modified HSSZ-13 zeolite in polyetherimide polymer matrix for gas separation. Journal of Membrane Science 288, 195
207. Hussain, A., Hägg, M.-B., 2010. A feasibility study of CO2 capture from flue gas by a facilitated transport membrane. Journal of Membrane Science 359, 140
148. Ismail, A.F., Khulbe, K.C., Matsuura, T., 2015. Gas Separation Membranes: Polymeric and Inorganic. Springer International Publishing, Switzerland. Iulianelli, A., Basile, A., Li, H., Van den Brink, R.W., 2011. 7-Inorganic membranes for pre-combustion carbon dioxide (CO2) capture. In: Basile, A., Nunes, S.P. (Eds.), Advanced Membrane Science and Technology for Sustainable Energy and Environmental Applications. Woodhead Publishing, pp. 184
213. Japip, S., Wang, H., Xiao, Y., Chung, T.S., 2014. Highly permeable zeolitic imidazolate framework (ZIF)-71 nano-particles enhanced polyimide membranes for gas separation. Journal of Membrane Science 467, 162
174. Japip, S., Xiao, Y., Chung, T.-S., 2016. Particle-size effects on gas transport properties of 6FDA-Durene/ZIF-71 mixed matrix membranes. Industrial & Engineering Chemistry Research 55, 9507
9517. Jeazet, H.B., Koschine, T., Staudt, C., Raetzke, K., Janiak, C., 2013. Correlation of gas permeability in a metal-organic framework MIL-101 (Cr)-polysulfone mixed-matrix membrane with free volume measurements by positron annihilation lifetime spectroscopy (PALS). Membranes 3, 331
353. Jones, C.W., Koros, W.J., 1994. Carbon molecular sieve gas separation membranes-I: preparation and characterization based on polyimide precursors. Carbon 32, 1419
1425. Kapantaidakis, G., Kaldis, S., Sakellaropoulos, G., Chira, E., Loppinet, B., Floudas, G., 1999. Interrelation between phase state and gas permeation in polysulfone/polyimide blend membranes. Journal of Polymer Science Part B: Polymer Physics 37, 2788
2798. Kayvani Fard, A., McKay, G., Buekenhoudt, A., Al Sulaiti, H., Motmans, F., Khraisheh, M., et al., 2018. Inorganic membranes: preparation and application for water treatment and desalination. Materials 11, 74. Khan, A.L., Li, X., Vankelecom, I.F.J., 2011. SPEEK/Matrimid blend membranes for CO2 separation. Journal of Membrane Science 380, 55
62. Kim, S., Lee, Y.M., 2015. Rigid and microporous polymers for gas separation membranes. Progress in Polymer Science 43, 1
32. Kiyono, M., Williams, P.J., Koros, W.J., 2010. Effect of pyrolysis atmosphere on separation performance of carbon molecular sieve membranes. Journal of Membrane Science 359, 2
10. Kosinov, N., Gascon, J., Kapteijn, F., Hensen, E.J.M., 2016. Recent developments in zeolite membranes for gas separation. Journal of Membrane Science 499, 65
79. Krishna, R., 2009. Describing the diffusion of guest molecules inside porous structures. The Journal of Physical Chemistry C 113, 19756
19781. Krishna, R., van Baten, J.M., 2010. In silico screening of zeolite membranes for CO2 capture. Journal of Membrane Science 360, 323
333. Lalia, B.S., Kochkodan, V., Hashaikeh, R., Hilal, N., 2013. A review on membrane fabrication: structure, properties and performance relationship. Desalination 326, 77
95.

286

Carbon Dioxide Capture and Conversion

Lau, H.S., Yong, W.F., 2021. Recent progress and prospects of polymeric hollow fiber membranes for gas application, water vapor and particulate matters removal. Journal of Materials Chemistry A 9, 26454
26497. Li, K., 2007. Ceramic Membranes for Separation and Reaction. John Wiley & Sons Ltd, West Sussex, England. Li, H., Haas-Santo, K., Schygulla, U., Dittmeyer, R., 2015. Inorganic microporous membranes for H2 and CO2 separation: review of experimental and modeling progress. Chemical Engineering Science 127, 401
417. Liang, C.Z., Chung, T.S., Lai, J.Y., 2019. A review of polymeric composite membranes for gas separation and energy production. Progress in Polymer Science 97, 101141. Liang, K., Grebowicz, J., Valles, E., Karasz, F., MacKnight, W., 1992. Thermal and rheological properties of miscible polyethersulfone/polyimide blends. Journal of Polymer Science Part B: Polymer Physics 30, 465
476. Liao, J., Wang, Z., Gao, C., Li, S., Qiao, Z., Wang, M., et al., 2014. Fabrication of highperformance facilitated transport membranes for CO2 separation. Chemical Science 5, 2843
2849. Lin, Y.S., Duke, M.C., 2013. Recent progress in polycrystalline zeolite membrane research. Current Opinion in Chemical Engineering 2, 209
216. Lin, R., Hernandez, B.V., Ge, L., Zhu, Z., 2018. Metal organic framework based mixed matrix membranes: an overview on filler/polymer interfaces. Journal of Materials Chemistry A 6, 293
312. Liu, C., Wilson, S.T., 2008. Mixed matrix membranes incorporating microporous polymers as fillers. US Patent. Lloyd, D.R., Kinzer, K.E., Tseng, H.S., 1990. Microporous membrane formation via thermally induced phase separation. I. Solid-liquid phase separation. Journal of Membrane Science 52, 239
261. Loeb, S., Sourirajan, S., 1963. Sea water demineralization by means of an osmotic membrane. Saline Water Conversion-II. American Chemical Society, pp. 117
132. Loloei, M., Moghadassi, A., Omidkhah, M., Amooghin, A.E., 2015. Improved CO2 separation performance of Matrimid 5218 membrane by addition of low molecular weight polyethylene glycol. Greenhouse Gases: Science and Technology 5, 530
544. Lu, Q., Gao, F., Komarneni, S., Mallouk, T.E., 2004. Ordered SBA-15 nanorod arrays inside a porous alumina membrane. Journal of the American Chemical Society 126, 8650
8651. Mannan, H.A., Mukhtar, H., Murugesan, T., Nasir, R., Mohshim, D.F., Mushtaq, A., 2013. Recent applications of polymer blends in gas separation membranes. Chemical Engineering & Technology 36, 1838
1846. Matsuyama, H., Berghmans, S., Lloyd, D.R., 1999. Formation of anisotropic membranes via thermally induced phase separation. Polymer 40, 2289
2301. Maxwell, J.C., 1954. A Treatise on Electricity and Magnetism. Dover Publications Inc, New York. Mazinani, S., Darvishmanesh, S., Ramazani, R., Van der Bruggen, B., 2017. Miscibility of polyimide blends: physicochemical characterization of two high performance polyimide polymers. Reactive and Functional Polymers 111, 88
101. Mazinani, S., Ramezani, R., Darvishmanesh, S., Molelekwa, G.F., Di Felice, R., Van der Bruggen, B., 2018. A ground breaking polymer blend for CO2/N2 separation. Journal of CO2 Utilization 27, 536
546. McKeown, N.B., Budd, P.M., 2006. Polymers of intrinsic microporosity (PIMs): organic materials for membrane separations, heterogeneous catalysis and hydrogen storage. Chemical Society Reviews 35, 675
683. Merkel, T.C., Lin, H., Wei, X., Baker, R., 2010. Power plant post-combustion carbon dioxide capture: an opportunity for membranes. Journal of Membrane Science 359, 126
139.

Application of membrane technology for CO2 capture and separation

287

Monsalve-Bravo, G.M., Bhatia, S.K., 2018. Modeling permeation through mixed-matrix membranes: a review. Processes 6, 172. Mulder, M., 1996. Basic Principles of Membrane Technology, second ed. Kluwer Academic, Dordrecht, Boston. Murali, R.S., Ismail, A., Rahman, M., Sridhar, S., 2014. Mixed matrix membranes of Pebax-1657 loaded with 4A zeolite for gaseous separations. Separation and Purification Technology 129, 1
8. Musselman, I., Balkus Jr., K., Ferraris, J., 2009. Mixed-matrix membranes for CO2 and H2 gas separations using metal-organic framework and mesoporus hybrid silicas. In: Final Scientific/Technical Report, University Of Texas At, Dallas, TX. Musto, P., Karasz, F.E., MacKnight, W.J., 1991. Hydrogen bonding in polybenzimidazole/poly(ether imide) blends: a spectroscopic study. Macromolecules 24, 4762
4769. Naderi, A., Chung, T.-S., Weber, M., Maletzko, C., 2019. High performance dual-layer hollow fiber membrane of sulfonated polyphenylsulfone/polybenzimidazole for hydrogen purification. Journal of Membrane Science 591, 117292. Pan, Y., Wang, B., Lai, Z., 2012. Synthesis of ceramic hollow fiber supported zeolitic imidazolate framework-8 (ZIF-8) membranes with high hydrogen permeability. Journal of Membrane Science 421
422, 292
298. Park, H.B., Kamcev, J., Robeson, L.M., Elimelech, M., Freeman, B.D., 2017. Maximizing the right stuff: the trade-off between membrane permeability and selectivity. Science 356. 10.1126/science.aab0530. Paul, D.R., Newman, S., 1978. Polymer Blends, Vol. 2. Academic Press, New York. Qin, Y., 2016. 5
Applications of advanced technologies in the development of functional medical textile materials. In: Qin, Y. (Ed.), Medical Textile Materials. Woodhead Publishing, pp. 55
70. Rabiee, H., Alsadat, S.M., Soltanieh, M., Mousavi, S.A., Ghadimi, A., 2015. Gas permeation and sorption properties of poly (amide-12-b-ethyleneoxide)(Pebax1074)/SAPO34 mixed matrix membrane for CO2/CH4 and CO2/N2 separation. Journal of Industrial and Engineering Chemistry 27, 223
239. Rafiq, S., Man, Z., Maitra, S., Maulud, A., Ahmad, F., Muhammad, N., 2011a. Preparation of asymmetric polysulfone/polyimide blended membranes for CO2 separation. Korean Journal of Chemical Engineering 28, 2050
2056. Rafiq, S., Man, Z., Maulud, A., Muhammad, N., Maitra, S., 2011b. Effect of varying solvents compositions on morphology and gas permeation properties on membranes blends for CO2 separation from natural gas. Journal of Membrane Science 378, 444
452. Ren, J., Wang, R., 2011. Preparation of polymeric membranes. Membrane and Desalination Technologies. Springer, pp. 47
100. Robeson, L.M., 2008. The upper bound revisited. Journal of Membrane Science 320, 390
400. Rogelj, J., Elzen, Md, Höhne, N., Fransen, T., Fekete, H., Winkler, H., et al., 2016. Paris Agreement climate proposals need a boost to keep warming well below 2 OC. Nature 534, 631
639. Rungta, M., Wenz, G.B., Zhang, C., Xu, L., Qiu, W., Adams, J.S., et al., 2017. Carbon molecular sieve structure development and membrane performance relationships. Carbon 115, 237
248. Salehian, P., Yong, W.F., Chung, T.-S., 2016. Development of high performance carboxylated PIM-1/P84 blend membranes for pervaporation dehydration of isopropanol and CO2/CH4 separation. Journal of Membrane Science 518, 110
119. Sanyal, O., Hicks, S.T., Bhuwania, N., Hays, S., Kamath, M.G., Karwa, S., et al., 2018. Cause and effects of hyperskin features on carbon molecular sieve (CMS) membranes. Journal of Membrane Science 551, 113
122.

288

Carbon Dioxide Capture and Conversion

Saufi, S.M., Ismail, A.F., 2004. Fabrication of carbon membranes for gas separation: a review. Carbon 42, 241
259. Shogbon, C.B., Brousseau, J.-L., Zhang, H., Benicewicz, B.C., Akpalu, Y.A., 2006. Determination of the molecular parameters and studies of the chain conformation of polybenzimidazole in DMAc/LiCl. Macromolecules 39, 9409
9418. Steel, K.M., Koros, W.J., 2005. An investigation of the effects of pyrolysis parameters on gas separation properties of carbon materials. Carbon 43, 1843
1856. Suzuki, H., 1987. Composite membrane having a surface layer of an ultrathin film of cageshaped zeolite and processes for production thereof, US4699892A Pat., U.S. (Ed.). Tennison, S.R., 1998. Microporous ceramic membranes for gas separation processes. University of Bath. Tin, P.S., Chung, T.S., Liu, Y., Wang, R., 2004. Separation of CO2/CH4 through carbon molecular sieve membranes derived from P84 polyimide. Carbon 42, 3123
3131. Tomita, T., Suzuki, K., Nakayama, K., Yajima, K., Yoshida, S., Himeno, S., 2007. Synthesis and permeation properties of a DDR-type zeolite membrane for separation of CO2/CH4 gaseous mixtures. Industrial & Engineering Chemistry Research 46, 6989
6997. Uhlhorn, R., Burggraaf, A., 1991. Gas separations with inorganic membranes. Inorganic Membranes Synthesis, Characteristics and Applications. Springer, pp. 155
176. Venna, S.R., 2010. Molecular engineering design of the SAPO-34 and ZIF-8 membranes for CO2 separation from CH4 and N2. Electronic Theses and Dissertations. Paper 1489. Vu, D.Q., Koros, W.J., MilleR, S.J., 2003. Effect of condensable impurities in CO2/CH4 gas feeds on carbon molecular sieve hollow-fiber membranes. Industrial & Engineering Chemistry Research 42, 1064
1075. Walsh, D., Rostami, S., 1985. The miscibility of high polymers: the role of specific interactions. Key Polymers Properties and Performance. Springer, pp. 119
169. Wang, H., Chung, T.S., Paul, D.R., 2014. Physical aging and plasticization of thick and thin films of the thermally rearranged ortho-functional polyimide 6FDA
HAB. Journal of Membrane Science 458, 27
35. Wang, Y., Goh, S.H., Chung, T.-S., 2007. Miscibility study of Torlon polyamideimide with Matrimid 5218 polyimide and polybenzimidazole. Polymer 48, 2901
2909. Wang, S., Li, X., Wu, H., Tian, Z., Xin, Q., He, G., et al., 2016. Advances in high permeability polymer-based membrane materials for CO2 separations. Energy & Environmental Science 9, 1863
1890. Ward, J.K., Koros, W.J., 2011. Crosslinkable mixed matrix membranes with surface modified molecular sieves for natural gas purification: I. Preparation and experimental results. Journal of Membrane Science 377, 75
81. Wijmans, J.G., Baker, R.W., 1995. The solution-diffusion model: a review. Journal of Membrane Science 107, 1
21. Williamson, P., 2016. Scrutinize CO2 removal methods. Nature 530, 153
155. Wu, Z., 2019. Inorganic Membranes for Gas Separations, Membrane Separation Principles and Applications. Elsevier, pp. 147
179. Wu, X.M., Zhang, Q.G., Lin, P.J., Qu, Y., Zhu, A.M., Liu, Q.L., 2015. Towards enhanced CO2 selectivity of the PIM-1 membrane by blending with polyethylene glycol. Journal of Membrane Science 493, 147
155. Xie, K., Fu, Q., Qiao, G.G., Webley, P.A., 2019. Recent progress on fabrication methods of polymeric thin film gas separation membranes for CO2 capture. Journal of Membrane Science 572, 38
60. Yang, H., Xu, Z., Fan, M., Gupta, R., Slimane, R.B., Bland, A.E., et al., 2008. Progress in carbon dioxide separation and capture: a review. Journal of Environmental Sciences 20, 14
27.

Application of membrane technology for CO2 capture and separation

289

Yeo, Z.Y., Chew, T.L., Zhu, P.W., Mohamed, A.R., Chai, S.-P., 2012. Conventional processes and membrane technology for carbon dioxide removal from natural gas: a review. Journal of Natural Gas Chemistry 21, 282
298. Yong, W.F., Chung, T.-S., 2015. Miscible blends of carboxylated polymers of intrinsic microporosity (cPIM-1) and Matrimid. Polymer 59, 290
297. Yong, W.F., Kwek, K.H.A., Liao, K.S., Chung, T.S., 2015. Suppression of aging and plasticization in highly permeable polymers. Polymer 77, 377
386. Yong, W.F., Lee, Z.K., Chung, T.S., Weber, M., Staudt, C., Maletzko, C., 2016. Blends of a polymer of intrinsic microporosity and partially sulfonated polyphenylenesulfone for gas separation. ChemSusChem 9, 1953
1962. Yong, W.F., Li, F.Y., Chung, T.S., Tong, Y.W., 2014. Molecular interaction, gas transport properties and plasticization behavior of cPIM-1/Torlon blend membranes. Journal of Membrane Science 462, 119
130. Yong, W.F., Li, F.Y., Xiao, Y.C., Li, P., Pramoda, K.P., Tong, Y.W., et al., 2012. Molecular engineering of PIM-1/Matrimid blend membranes for gas separation. Journal of Membrane Science 407
408, 47
57. Yong, W.F., Zhang, H., 2021. Recent advances in polymer blend membranes for gas separation and pervaporation. Progress in Materials Science 116, 100713. Zhang, Y., Balkus Jr, K.J., Musselman, I.H., Ferraris, J.P., 2008. Mixed-matrix membranes composed of Matrimid and mesoporous ZSM-5 nanoparticles. Journal of Membrane Science 325, 28
39. Zhang, Y., Sunarso, J., Liu, S., Wang, R., 2013. Current status and development of membranes for CO2/CH4 separation: a review. International Journal of Greenhouse Gas Control 12, 84
107. Zhao, S., Liao, J., Li, D., Wang, X., Li, N., 2018. Blending of compatible polymer of intrinsic microporosity (PIM-1) with Tröger’s Base polymer for gas separation membranes. Journal of Membrane Science 566, 77
86. Zornoza, B., Seoane, B., Zamaro, J.M., Téllez, C., Coronas, J., 2011. Combination of MOFs and zeolites for mixed-matrix membranes. ChemPhysChem 12, 2781
2785.

CHAPTER 11

Sequestration of carbon dioxide into petroleum reservoir for enhanced oil and gas recovery Minhaj Uddin Monir1, Azrina Abd Aziz2, Fatema Khatun2, Mostafa Tarek3 and Dai-Viet N. Vo4 1

Department of Petroleum and Mining Engineering, Jashore University of Science and Technology, Jashore, Bangladesh Faculty of Civil Engineering Technology, Universiti Malaysia Pahang, Kuantan, Pahang, Malaysia 3 Faculty of Chemical and Natural Resources Engineering, Universiti Malaysia Pahang, Kuantan, Pahang, Malaysia 4 Center of Excellence for Green Energy and Environmental Nanomaterials, Nguyen Tat Thanh University, Ho Chi Minh City, Vietnam 2

Abbreviations IEA EOR EGR GHGs OOIP IFT ppm

International Energy Administration Enhanced oil recovery Enhanced gas recovery Greenhouse gases Overall on-site initial oil Interfacial tension Parts per million

11.1 Introduction Global energy demand has increased by 28% due to the ever-growing population, and the basic energy needs are being met by fossil fuels. Approximately 80% of the global energy consumption is met by natural sources, although these sources are nonrenewable (Asif and Muneer, 2007). They also reported that the world’s electricity demand has been met by nonrenewable fossil-based fuels for thousands of years and are called primary energy sources. In contrast, the International Energy Administration (IEA) reported in their analyses that fossil fuels will be the primary source of energy supply for another half-century. It is high time to develop oil/gas recovery (EOR/EGR) techniques. EOR/EGR is a tertiary recovery method that has been extended to existing oil/gas fields to obtain existing oil/gas that is trapped or may not be recovered by Carbon Dioxide Capture and Conversion DOI: https://doi.org/10.1016/B978-0-323-85585-3.00005-5

© 2022 Elsevier B.V. All rights reserved.

291

292

Carbon Dioxide Capture and Conversion

primary and secondary recovery techniques. Up to 20% of the overall onsite initial oil (OOIP) has been extracted from the oil reserve and referred to as primary oil production (Moghadasi et al., 2018). By practicing the primary recovery method (simple drilling and spraying via pressure variations), 5%
10% of oil can be recovered and more than 30%
40% can be recovered by secondary methods (water flooding or natural gas injection) (Qin et al., 2015). Zhang et al. (2014) studied the effects of imbibition experiments utilizing a moderate salinity reservoir and a high-salinity reservoir solution and a fitting nanofluid that displaces crude oil from Berea sandstone (water-wet) and single-glass capillaries. Johannessen and Spildo (2013) observed in their study that while injecting low-salinity (LS) water, destabilizing oil layers adhering to mineral surfaces could lead to EOR. In this regard, surfactant flood is a known EOR technique involving raising the capillary number. A petroleum reservoir is a subsurface accumulation of hydrocarbons found in porous or broken rock formations (Dandekar, 2013). Petroleum reservoirs are commonly known as conventional reservoirs. Conventional petroleum reservoirs have strong physical properties of usually 15%
35% porosity and generally 10 3 μm2 (50
1000) permeability (Zou, 2017). The naturally occurring hydrocarbons, such as crude oil or natural gas, are trapped in traditional reservoirs by overlying rock layers with lower permeability, while in unconventional reservoirs, the rocks have high porosity and reduced permeability, which holds the hydrocarbons trapped in place, thus not having cap rock. Their pores are mainly found in giant pore areas. On the other hand, unconventional petroleum reservoirs have usually 2%
10% porosity and 10 3 μm2 permeability. Their pores are mainly found in micropore and ultra-micropore zones (Zou, 2017). Sources and reservoir rock formations are responsible for the formation of crude oil and natural gas (Speight, 2020). Various media (liquids and gases) have been used to inject more crude from tight oil sources into the reservoirs (Zhou et al., 2020). EOR techniques are used in addition to water, substances, or gases (CO2, CO and N2) to improve oil flow velocity (Satter and Iqbal, 2016). The gas injection process is a secondary EOR method in which gas (CO2) is pumped into the reservoir to maintain pore pressure via a vertical well, as reported by Khatun et al. (2016). CO2 is a major greenhouse gas responsible for global warming. CO2 in the atmosphere will reach 590 ppm by 2100 (Chen et al., 2014). With unprecedented changes taking place over the past few decades, climate change, greenhouse gases, and CO2 pose a serious danger to our

Sequestration of carbon dioxide into petroleum reservoir for enhanced oil and gas recovery

293

environment (Manisalidis et al., 2020). Greenhouse gases are mainly responsible for climate change, and the concentration of CO2 in all those gases is high (Yoro and Daramola, 2020). The greenhouse effect, which is the main cause of global climate change, is considered a loop of energy transport processes, leading to the warming effect caused by greenhouse gas emissions (Stallinga, 2019). Greenhouse gases such as CO2, nitrous oxide (N2O), and methane (CH4), with a high proportion of CO2 in all gases, have significantly contributed to climate change. Therefore, through injection into the petroleum reservoir, CO2 gas could be used for EOR/ EGR.

11.2 Oil and gas reservoirs Oil and gas are naturally derived from organic material, which is mainly deposited as sediments formed over millions of years on the seabed (Littke and Zieger, 2020). The recoverable oil and gas deposits could be found there if an appropriate mixture of the source rock, the oil reserve, the caprock, and the trap is available in the area (Cao et al., 2005) (Fig. 11.1). Oil and gas deposits are usually located in sedimentary rocks. These are normally found in between fragmented igneous or metamorphic rocks. Igneous and metamorphic rocks form under high pressure and temperature, which is not favorable for emerging oil reservoirs. Sandstone and carbonate formations are the primary reservoir rocks (Ganat, 2020). Typically, the physical properties and structure of sandstone and carbonate

Figure 11.1 Schematic diagram of an oil and gas reservoir.

294

Carbon Dioxide Capture and Conversion

rocks differ from each other (Ganat, 2020). Usually, igneous and metamorphic rocks lack the interconnected pore space needed to form a conduit for oil to flow into the well. Although it may be shaped like a piece of sandstone, a metamorphic rock is subjected to extreme heat and stress. Sedimentary rocks are essential for a productive oil reservoir. Reservoir rocks are porous and are often saturated with water, oil, and gas in different proportions (Ganat, 2020). Petroleum reservoirs contain oil, gas, or both (Fangzheng, 2019). Significant properties include hardness, lithology, the porosity of the rock, overall compressibility of the rock, and permeability of the rock. These characteristics influence the fluid movement inside the reservoir and therefore its performance. To model the reservoir behavior and predict efficiency well, reservoir engineers must consider these properties. To build a hydrocarbon reservoir, many primary components must be present. Then, there must be a source of hydrocarbons. It is widely believed that oil is made from aquatic life. When the leftovers are baked and buried, oil and gas form. Secondly, ventilation from the rock source to the rock reservoir should be present. Hydrocarbons are commonly formed in rocks and cannot be directly used in modern processing techniques. To obtain usable hydrocarbons, they must be able to flow through wells. The flow rate must be high to allow the well to be economically viable. Two basic aspects control the reservoir’s economic viability: porosity and permeability (Ganat, 2020). In the reservoir study, the scientist uses core samples taken from the test wells to classify lithology (Eq. 11.1). Vpore Vbulk

ϕ

(11.1)

Permeable structures, including sandstones, are those that transfer fluids easily and appear to have many large, well-connected pores. The thinner or blended grains, with larger or less twisted pores, appear to be impermeable formations, such as shales and siltstones. The relation between the reduction in pressure by the rock and the volumetric flow rate q is established by Darcy’s law (Eq. 11.2), where the factor k of proportionality is called permeability. q

k

AΔp μΔl

(11.2)

for a suitable fluid μ that flows in a cylindrical rock body horizontally with length μ and cross-section A.

Sequestration of carbon dioxide into petroleum reservoir for enhanced oil and gas recovery

295

11.3 Advanced oil and gas recovery mechanism Primary recovery typically uses only reservoir pressure to stimulate production. Around 30% of the oil in the reservoir is normally derived via traditional pressure extraction techniques. Secondary recovery requires water, or sometimes steam, to be pumped in to maintain the pressure in the petroleum reservoir. The water is pumped back into the tank after it is flooded, to sustain the pressure of the reservoir (also known as the vacuum substitute) and sweep or displace the oil from the reservoir to drive it into the well. The concentration restored (known as the recovery factor) is increased by water injection and the reservoir production rate is sustained for a longer period. A term used by a wide variety of approaches to increase the volume of crude oil extracted from the oil field is tertiary or increased EOR. It is often connected to and followed by the formation of an area by water injection or by water flooding. Thermal recovery methods are usually applied to viscous, hard crude oil, which involve the use of heat or thermal energy in the tank to raise the temperature of the oil, which, in turn, decreases its viscosity. To improve the recovery of oil, chemical methods are mainly used. It is a displacement process in which various kinds of chemical additives are used. The purpose of applying methods of chemical flooding is to control volatility by adding polymers to mitigate pumped water volatility and by using surfactants and/or alkalis to mitigate interfacial tension (IFT). Due to a shortage of high-temperature compatible chemical products and high salinity, chemical EOR is currently faced with major challenges, especially in light oil reservoirs (Hashemi et al., 2014). A schematic diagram of the oil well and gas well used for the extraction of oil and gas, respectively, from the reservoir is shown in Fig. 11.2. Three processes are successfully preserved by chemical EOR technology: polymer, surfactant-polymer, and alkaline processes. The most useful and oldest EOR procedure is gas injection or flooding. Two key classes of miscible and immiscible gas injections are involved in gas injection techniques. Gas is not miscible in the shape of immiscible reservoir fluid. The mechanism of miscibility is for solvent extraction to obtain miscibility. The most popular gas injection techniques include injection of nitrogen and flue gas, hydrocarbon injection, and CO2 flooding. A set of screening criteria for each EOR method was suggested by Taber et al. (1997). Propitious requirements such as gravity, temperature, and crude oil content must be met for miscible displacement to be used. When the oil in the

296

Carbon Dioxide Capture and Conversion

Figure 11.2 Schematic diagram of an oil well and gas well used for the extraction of oil and gas, respectively, from the reservoir.

reservoir combines with the pumped CO2, a single liquid phase emerges. Their activity results in the swelling and lack of viscosity of crude oil, while, on the other hand, the effect of surface tension decreases. As a result, the oil must flow to the output wells. For low-pressure or heavy-duty oil fields, the immiscible displacement system is used. In this process, CO2 is injected at a slow speed into the crest of the reservoir, simulating the gas cap and pushing the oil into the output wells. In crude oil, CO2 dissolves slowly, which causes swelling. The immiscible displacement process can be compared with the flooding water system, because when the flooding water system is used, CO2 plays a similar role to that of water.

11.3.1 Enhanced oil recovery EOR is an approach to improve oil recovery during primary rehabilitation (rehabilitation by the key moving mechanism) and secondary water recovery. EOR is also called tertiary oil recovery. EOR could increase oil production by 60%
65% as compared to increase in production volume by 20%
30% via primary drive mechanisms and 40% via secondary drive mechanisms (Tunio et al., 2011). The weight resistance in the reservoir may be due to water-weight, oil-weight, or moderate-weight structures, based on the fluid distribution around mineral particles (Zhou et al., 2020). Shiran and Skauge (2013) reported that low salinity brine injection was granted considerable attention as a waterflooding technique for EOR.

Sequestration of carbon dioxide into petroleum reservoir for enhanced oil and gas recovery

297

The use of low-salinity water in conjunction with other proven EOR processes (e.g., surfactant flooding, polymer flooding) has attracted considerable attention. They found that the final recovery factor for original oil in place (OOIP) improved to around 90%. Setting the rock/oil reservoir to create optimal conditions for the recovery of waste oil includes the following: 1. Reduction of interface tension (IFT) between fluid and oil displacement. 2. Modification of the wettability of the rock repository. 3. Raising the viscosity of the drive water. 4. Increasing the number of the capillary. 5. Minimizing capillary power. 6. Overseeing mobility. 7. Eliminating oil viscosity. 8. Swelling of the oil.

11.3.2 Enhanced gas recovery Primary and secondary recovery methods contribute to maximum gas extraction from the reservoir. EGR can be done using CO2 since it is thicker than natural gas. CO2 is injected into the depleted gas tank base and continues to accumulate, causing excess natural gas to settle over it, which then drives natural gas into output wells (Khatun et al., 2016). However, a high concentration of natural gas can be recovered from several gas fields without the use of enhanced recovery technologies.

11.3.3 Challenges and strategy for increased oil/gas recovery The main challenges facing EOR/EGR are as follows: 1. Capturing CO2 from different sources. 2. Storing CO2 in the tank for injection into the well reservoir. 3. Capturing CO2 from petrochemical process sources and flares, which have been identified as one of the methods to limit greenhouse gas pollution in the environment (Ravanchi and Sahebdelfar, 2014).

11.4 Fundamentals of CO2 gas injection CO2 is injected through a high-pressure oil-bearing stratum as part of the CO2-EOR process. CO2 injection oil displacement is focused on the phase behavior of gas and petroleum mixtures, which relies heavily on reservoir temperature, pressure, and oil composition. Two primary forms of CO2-EOR

298

Carbon Dioxide Capture and Conversion

processes are in practise today. Miscible CO2-EOR is a multicontact system that works based on responses shared between the injected CO2 and the oil reservoir. In this multicontact process, CO2 vaporizes lighter fractions of oil into the pumped CO2 layer and condenses CO2 into the oil phase in the reservoir. This results in the formation of two miscible storage fluids (mixing in both parts), with favorable low viscosity properties, greater stability, and low interfacial tension. The primary objective of miscible CO2-EOR is to restore and reduce waste oil saturation in the pores of the reservoir during water flow. The standardized diagram (Fig. 11.3) shows the dynamics of the miscible CO2-EOR process. Miscible CO2-EOR is by far the most common means of CO2-EOR. The immiscible CO2-EOR happens when the reservoir pressure is low or when the oil content of the tank is less suitable (heavier). The main processes involved in the formation of immiscible CO2 include the following: 1. Swelling of oil when the oil is flooded in CO2. 2. Decrease in viscosity of the mixture of swollen oil and CO2. 3. Mobilization and in many instances commercialization of a portion of the current oil reservoir via using a combination of mechanisms.

11.4.1 Sources of CO2 Carbon is an important organic factor and is present in all living organisms (Kumar et al., 2006). CO2 absorption in the atmosphere rose from approximately 277 ppm (Joos and Spahni, 2008) in the industrial era in 1750 to 385 ppm in 2008 (Stein and Leskiw, 2000), 395 ppm in 2013 (Bruhwiler et al., 2014), and 406 ppm in 2016 (Bruhwiler et al., 2014). It is projected that CO2 absorption would be about 530 ppm in 2050 and 780 ppm in 2100 (Favero and Mendelsohn, 2017). CO2 absorption and utilization are important in reducing greenhouse gas emissions (Mac Dowell et al., 2017). Allwood et al. (2010) reported that two-thirds of anthropogenic CO2 was released by emissions from energy-based operation, with 36% being generated. The maximum CO2 emissions, on the other hand, come from fossil fuel combustion and industrial operation, generating 78% of CO2 emissions from cement manufacturing alone between 1970 and 2011 (Edenhofer, 2015). The primary cause of rapid CO2 pollution is the rapid growth in population, leading to ever-increasing demand of energy for sustainability and preservation of life. In comparison, use of conventional fossil sources for energy supply has decreased over the years, and

Sequestration of carbon dioxide into petroleum reservoir for enhanced oil and gas recovery

299

nonrenewable sources of energy also need innovative technologies for their revival. Both natural and human causes of CO2 pollution are identified. Natural sources include decomposition, the release from oceans, and breathing. Artificial sources of CO2 pollution include cement manufacturing, forestry, and combustion of fossil fuels such as coal, oil, and natural gas. CO2 emissions from artificial sources have increased since the industrial revolution, which include human activities such as burning oil, coal, and gas, as well as deforestation, leading to increased concentrations of CO2 in the atmosphere, and thus disrupting the pre-Industrial Revolution carbon cycle equilibrium. About 87% of all human-produced CO2 emissions come from the burning of fossil fuels such as coal, natural gas, and oil. In addition to human activities, CO2 is often emitted into the environment by natural causes. The Earth’s seas, land, trees, livestock, and volcanoes are natural causes of pollution caused by CO2. The natural sources of CO2 pollution cause much higher pollution than human sources. The volume of CO2 emitted by natural sources has been mainly offset by natural carbon sinks over thousands of years, leading to natural equilibrium consistent levels of CO2 in the atmosphere. Ocean
atmosphere trade accounts for 42.84% of all-natural CO2 pollution. Other essential environmental causes include plant and animal ventilation (28.56%), soil breathing, and decomposition (28.56%). Volcanic eruptions (0.03%) also emit a limited volume of CO2 in the atmosphere. 11.4.1.1 Fossil fuel combustion and usage The main human source of CO2 emissions is fossil fuel combustion. This results in 87% of human emissions of CO2. Burning these fuels releases energy, which is most frequently transformed into heat, electricity, or energy for transmission. Coal is the fossil fuel with the highest carbon intensity. Approximately 2.5 tons of CO2 equivalent is produced with every ton of burned coal. Burning such fuels, for example, releases energy, but CO2 is also produced as a by-product. This is because during this process almost all of the carbon stored in fossil fuels is converted into CO2. 11.4.1.2 Electricity/heat sector Electricity and heat generation is a man-made means of CO2 emission. This sector produced 41% of the CO2 emissions from fossil fuels in 2010. This activity depends heavily on gas, the most carbon-intensive fossil fuel known to date, justifying the gigantic carbon footprint of this sector.

300

Carbon Dioxide Capture and Conversion

11.4.1.3 Transportation sector The second greatest cause of anthropogenic CO2 pollution is the transport industry. In 2010, the shipping industry produced 22% of the CO2-related pollution from fossil fuels. This industry is highly energy-intensive and depends heavily on petroleum fuels such as petrol, gasoline, kerosene, and so on to meet its energy requirements. Emissions connected to transport have increased exponentially, expanding by 45% in less than two decades since the 1990s. 11.4.1.4 Industrial sector The industrial sector is the third major cause of CO2 pollution. In 2010, the industry emitted 20% of CO2-related fossil fuels. Industrial sectors include manufacturing, building, mining, and agriculture. Many processing plants use fossil fuels directly to produce heat and steam required at different stages of operation. For example, cement factories burn fossil fuels to produce the heat required to convert calestone into concrete at 1450°C. 11.4.1.5 Land-use changes Changes in land use is another significant cause of pollution by CO2 internationally, contributing 9% of emissions of human CO2, amounting to 3.3 billion tons of emissions of CO2 in 2011. Changes in land use include turning natural ecosystems into places for human use, including farmland and cities. From 1850 to 2000, approximately 396
690 billion tonnes, or around 28%
40%, of overall anthropogenic CO2 emissions were produced from agricultural usage and land-use transition. Deforestation is permanent destruction of forest and is well known for its contribution to greenhouse gas emissions. Forests are burned for wood or converted into fields and pastures in certain places. As forested land is burned, significant volumes of greenhouse gas are emitted and CO2 levels are raised. Trees serve as a drain of biomass. They extract CO2 from the atmosphere via photosynthesis. In burned woods, trees are either charred or left to burn, contributing to CO2 emissions in the environment. 11.4.1.6 Industrial processes Many industrial processes emit large quantities of emissions from the chemical reactions carried out in the manufacturing phase. Industrial activities account for 4% of the human production of CO2, and in 2011, it contributed 1.7 billion tons. Many manufacturing activities produce CO2

Sequestration of carbon dioxide into petroleum reservoir for enhanced oil and gas recovery

301

explicitly through the burning of fossil fuels and indirectly through the implementation of fossil-fuel electricity. As a byproduct of the chemical reaction, this phase generates significant concentrations of CO2. The processing of 1000 kg cement generates about 900 kg of CO2. On average, 1.9 tons of CO2 is released per ton of steel manufactured.

11.4.2 Surface facilities The CO2 EOR/EGR surface infrastructure must be designed on a case-by-case basis. The specifications depend on the usable volume of CO2, its nature, plant location and its proximity to the injection site, reservoir conditions, production forecasts and processing requirements, the handling of the produced fluids, and a detailed environmental assessment. CO2 EOR/EGR surface facilities are usually very expensive to build and necessarily entail trade-offs for different options. Economics plays an important role in the selection of options under a variety of conditions. A schematic diagram of CO2 EOR/EGR is given in Fig. 11.3. An option is selected following a thorough analysis of all alternatives available. Selection of any such design involves multiple phases, including the following: 1. A feasibility study to address the technical and economic viability of the plan. 2. A pre-FEED analysis of progress and construction, concentrating on a wider technical and engineering scale. 3. A full FEED study on the real installations’ nuts and bolts. The installations needed for CO2 EOR/EGR are almost the same as required for waterflooding operations and include storage lines, CO2 metering lines, and distribution lines, which are also required for building CO2-EOR facilities. The whole process is divided into three essential subprocesses: 1. Extraction: Due to advancements made in well production, CO2 gas is extracted from an increasingly rich CO2 separator gas. 2. Processing: It involves purifying CO2 after isolation from the separator gas and CO2 until compression. 3. Compression: CO2 is compressed to maximize the pressure of its injection. During the initial injection, CO2 easily moves into the rock pores. CO2 tends to permeate rock based on a pressure gradient. When CO2 penetrates the rock, oil migrates into bulk CO2 in pores depending on

302

Carbon Dioxide Capture and Conversion

Figure 11.3 Schematic diagram of CO2 EOR/EGR. recovery.

, Enhanced oil/gas

swelling and lower viscosity. Subsequently, the CO2 pressure becomes stable within the rock. Oil development now depends only on concentration gradient-driven diffusion. Oil in bulk CO2 is well transported via pores (Fig. 11.3).

11.5 Technologies for enhanced oil/gas recovery 11.5.1 CO2 injection for enhanced oil recovery It is projected that 80% of the world’s oil reserves are capable of CO2 injection to maximize oil recovery. The supply and costs of CO2 is reduced by enhanced petroleum recovery operations with CO2 (Vega and Kovscek, 2010). The energy-intensive and fossil-fuel sectors are major contributors of pollution due to CO2 emissions. A global rise in CO2 levels is related to climate change. The technology to catch and store CO2 (CCS) to reduce the carbon footprint of these activities is being developed. Options vary from the isolation after combustion to innovative combustion options that can be practiced in other sectors. The sequestration of anthropogenic CO2 in oil fields is now a reality. CO2-EOR was first attempted in Scurry County, Texas, USA, in 1972. It is commonly used in the USA in offshore oilfields. There is more than 4800 km of CO2 pipeline spread in the southeast of USA (Ansarizadeh et al., 2015). As CO2 is injected into the reservoir, it interacts with the oil

Sequestration of carbon dioxide into petroleum reservoir for enhanced oil and gas recovery

303

in the tank soil chemically and mechanically and creates optimum conditions for oil recovery. Some of these conditions are as follows: 1. Reduction of capillary forces stopping oil from going into the pores of the reservoir, thus reducing the interface tension between the oil and the storage rock. 2. Oil swelling, which relates to the rise in oil volume and the subsequent viscosity decrease. 3. Enhanced movement of the oil due to the formation of a desirable dynamic mechanism. 4. Maintenance of desirable oil and CO2 polyvalence characteristics to improve sweep volume efficiency (replacement). As a flame, CO2 begins to travel in the tank faster than gasoline. The mobility of oil and that of CO2 must be similar for CO2-EOR to be efficacious. Effective permeability and viscosity are the main mobility factors for each point. The volumetric sweeping performance usually declines as the CO2 and oil mobility ratio rises. Moreover, when the polyvalence ratio is greater than 1, the fluid flow is erratic, and the frontal displacement is not uniform. Consequently, CO2 circumvents the oil bank, long before the oil is used, so that the entire potential reservoir volume does not sweep away. Transportation of oil through CO2 injection depends on different factors relevant to the gas operation of the CO2 and the crude mixture, and the most critical of these are the reservoir temperature and the reservoir pressure. CO2 is pumped into a tank and used as an oil regeneration process. These situations may be pools of low-pressure or hard oils. CO2 is not entirely miscible with the oil under the above-described circumstances, but it still partly dissolves and induces swelling. The EOR methods are applied in the practical fields for the enhancement of oil recovery using CO2 gas injection (Table 11.1).

11.5.2 CO2 injection for enhanced gas recovery CO2 is pumped into gas reserves in small amounts. However, studies have shown that injections of CO2 improve natural gas generation by repressurization from a gas reservoir (Van der Burgt et al., 1992). The key benefit of injecting CO2 into a gas tank is that CO2 under almost all reservoir settings is denser and more viscous than natural gas. Gravitational and viscously stable floods are also likely. Khatun et al. (2016) proposed an EGR improvement scenario for the Bangladesh gas reservoir.

304

Carbon Dioxide Capture and Conversion

Table 11.1 Application of EOR (enhanced oil recovery) methods in practical fields. EOR methods

Oil field name

Description

References

Immiscible CO2EOR

Daqing oil field, China

Hill et al. (2020)

Miscible CO2EOR

Jilin prototypical CO2 flooding project, China

Started in 1963, suggested CO2 flooding could increase production by 10% CO2 flooding initiated in 2007, as of 2011 produced 119,000 tonnes

Miscible CO2EOR

Changqing oil field, China

95% pure CO2 injection

Weyburn, Saskatchewan, Canada

CO2-EOR

Joffre Viking field east of red deer, Alberta, Canada SACROC field in scurry country, Texas, USA

CO2-EOR

Initiated in 2000, reported recovery was 20%, approximately 44,000 bbl oil was produced Began in 2000, estimated incremental production over 30 years is 160 million barrels The first EOR project started in 1991, recovered 10%
25% OOIP from the abandoned oil field World’s first CO2-EOR project started in 1972, reported producing oil in 2008 is 24,000 barrels/day

Tang et al. (2014); Zhang et al. (2015) Ren et al. (2016)

Riding and Rochelle (2009) Pyo et al. (2003)

Crameik and Plassey (1972)

CO2 injection into a gas reservoir is still at a very early stage of development due to the complexities of the CO2 gas injection methods (Clemens and Wit, 2002). Moreover, this is the reason behind this technique drawing less attention—CO2-breakthrough creates a noticeable drop in gas production rate with increased CO2 production rate (Blok et al., 1997). Despite these disadvantages, the CO2-EGR still has its own advantages like CO2 and natural gas can be mixed with the physical properties of the resultant mixture being favorable for reservoir repressurization without extensive mixing (Oldenburg and Benson, 2002). The original concept of CO2-EGR was proposed by Van der Burgt et al.

Sequestration of carbon dioxide into petroleum reservoir for enhanced oil and gas recovery

305

(1992), following which several simulation works have been done by researchers to understand the method better (Ezekiel et al., 2020). CO2EGR becomes a complex flow and mass transfer process in a depleted gas reservoir with unfavorable reservoir properties, injection strategy, namely vertical or horizontal well injection, low injection rate, and unfavorable injection locations (Liu et al., 2021).

11.5.3 CO2 solubility in oil and gas Carbon neutrality is important for carbon sequestration. Many analysts in the petroleum sector see the carbon neutrality of sequestration activities as a final target (Ferguson et al., 2009). In other words, when oil or gas is withdrawn from the tank, the hydrocarbon energy is released, and CO2 is inserted back into the tank. In this field, Kovscek (2002) demonstrates a range of calculations. The author finds the carbon density of oil or gas to be a function of gravity and temperature relative to carbon density in CO2. In general, liquid hydrocarbon carbon density is somewhat higher than CO2, while natural gas carbon density is only marginally lower than CO2. The carbon density of CO2 is 20% higher for a variety of representative reservoir environments than natural gas. CO2 is more carbon-rich than natural gas in nearly all situations of practical significance. CO2 produced from the burning of natural gas can be contained at a predefined storage pressure and temperature in the initial gas reservoir.

11.5.4 CO2 injection facilities and process design considerations There are two major factors underlying CO2-EOR: technological factors and (fiscal) considerations. The technological consideration of CO2-EOR injection involves dynamic engineering and is different from reservoir to reservoir. While planning for CO2-EOR injection, a detailed overview of the area of the reservoir and the prospect of miscibility shall be considered. Primary factors to be considered include the residual crude, reduced miscibility strain, depth of the reservoir, oil API gravity, and formation dip angle.

11.6 Economic evaluation An in-depth study of the oil deposits of tomorrow has led to energy industry’s activities spreading beyond the boundaries of traditional discovery and development strategies. The EOR/EGR project calls for serious

306

Carbon Dioxide Capture and Conversion

consideration of a variety of issues, including the time period for research, assessments, project planning and construction, and, last but not least, the economics of these high-cost EOR ventures. It may be extended to every EOR/EGR reservoir on the earth. The reservoir characteristics and the production costs of EOR oil for a particular reservoir are entered into the model (Zekri and Jerbi, 2002), which then gives an approximation of: 1. the amount of crude oil from the project that will be produced; 2. the price covering all project expenses with an acceptable return on investment (ROI); 3. the timing for the extraction of reserves in the reservoir. Analysis from the economics viewpoint indicates that an increased gas recovery is cost-effective at CO2 purchasing rates of US$4
10 per ton (Oldenburg et al., 2004). The economics of the process are dependent on natural gas receipts and CO2 acquisition costs. The development of a CO2 EOR/EGR project is a capital-intensive undertaking. Boiling or reworking of wells, the construction of CO2 recycling plants and corrosion-resistant field manufacturing facilities, and the laying of CO2 storage and transportation pipelines are necessary for both injectors and suppliers. The single biggest expense of the project is the procurement of CO2. As such, operators always aim to maximize the costs of purchasing and injecting CO2 when absolutely necessary and reduce them otherwise.

11.7 Conclusions A summary of this chapter is as follows: 1. Improved oil recovery is an important step. There are numerous methods for EOR and CO2-EOR. 2. CO2-EOR procedure is used for mass-transfer oil extraction. If CO2 is injected into the oil tank, it reacts with the oil in place physically and chemically. The result is a drop in the capillary forces impeding the movement of liquid. 3. There are two main ways of CO2-EOR/EGR: mixed and unmixed displacement. 4. The pumped CO2 oil blends into the tank and creates a single fluid. Their contact contributes to the swelling of crude oil and reducing the viscosity of crude oil. As a result, the oil is expected to flow to the output wells.

Sequestration of carbon dioxide into petroleum reservoir for enhanced oil and gas recovery

307

5. The intangible displacement method is used in low-pressure or heavyduty petroleum areas. CO2 is injected steadily through the tank crest simulating the gas seal. CO2 partially dissolves in fuel oil, inducing swelling. 6. Core input variable changes are needed before EOR/EGR ventures can become economically feasible.

References Allwood, J.M., Cullen, J.M., Milford, R.L., 2010. Options for achieving a 50% cut in industrial carbon emissions by 2050. Environmental Science & Technology 2010 (44), 1888
1894. Ansarizadeh, M., Dodds, K., Gurpinar, O., Kalfa, U., Ramakrishnan, T., Sacuta, N., et al., 2015. Carbon dioxide—challenges and opportunities. Oilfield Review 27 (2), 36
50. Asif, M., Muneer, T., 2007. Energy supply, its demand and security issues for developed and emerging economies. Renewable Sustainable Energy Reviews 11 (7), 1388
1413. Blok, K., Williams, R., Katofsky, R., Hendriks, C.A., 1997. Hydrogen production from natural gas, sequestration of recovered CO2 in depleted gas wells and enhanced natural gas recovery. Energy 22 (2
3), 161
168. Bruhwiler, L., Dlugokencky, E., Masarie, K., Ishizawa, M., Andrews, A., Miller, J., et al., 2014. CarbonTracker-CH4: an assimilation system for estimating emissions of atmospheric methane. Atmospheric Chemistry and Physics 14 (16), 8269. Cao, J., Zhang, Y., Hu, W., Yao, S., Wang, X., Zhang, Y., et al., 2005. The permian hybrid petroleum system in the northwest margin of the Junggar Basin, northwest China. Marine and Petroleum Geology 22 (3), 331
349. Chen, L., Xu, Z., Li, J., Zhou, B., Shan, M., Li, Y., et al., 2014. Modifying graphite oxide nanostructures in various media by high-energy irradiation. RSC Advances 4 (2), 1025
1031. Clemens, T., Wit, K., 2002. CO2 enhanced gas recovery studied for an example gas reservoir. In: SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers. Crameik, T., Plassey, J., 1972. Carbon Dioxide Injection Project Sacroc Unit, Scurry County, Texas. In: Annual Meeting Papers, Division of Production. American Petroleum Institute. Dandekar, A.Y., 2013. Petroleum Reservoir Rock and Fluid Properties. CRC Press. Mac Dowell, N., Fennell, P.S., Shah, N., Maitland, G.C., 2017. The role of CO2 capture and utilization in mitigating climate change. Nature Climate Change 7 (4), 243
249. Edenhofer, O., 2015. Climate Change 2014: Mitigation of Climate Change. Cambridge University Press. Ezekiel, J., Ebigbo, A., Adams, B.M., Saar, M.O., 2020. Combining natural gas recovery and CO2-based geothermal energy extraction for electric power generation. Applied Energy 269, 115012. Fangzheng, J., 2019. Re-recognition of “unconventional” in unconventional oil and gas. Petroleum Exploration and Development 46 (5), 847
855. Favero, A., Mendelsohn, R., 2017. The land-use consequences of woody biomass with more stringent climate mitigation scenarios. Journal of Environmental Protection 8 (1), 61
73.

308

Carbon Dioxide Capture and Conversion

Ferguson, R.C., Nichols, C., Van Leeuwen, T., Kuuskraa, V.A., 2009. Storing CO2 with enhanced oil recovery. Energy Procedia 1 (1), 1989
1996. Ganat, T.A.-A.O., 2020. Fundamentals of Reservoir Rock Properties. Springer. Hashemi, R., Nassar, N.N., Almao, P.P., 2014. Nanoparticle technology for heavy oil insitu upgrading and recovery enhancement: opportunities and challenges. Applied Energy 133, 374
387. Hill, L.B., Li, X., Wei, N., 2020. CO2-EOR in China: a comparative review. International Journal of Greenhouse Gas Control 103, 103173. Johannessen, A.M., Spildo, K., 2013. Enhanced oil recovery (EOR) by combining surfactant with low salinity injection. Energy & Fuels 27 (10), 5738
5749. Joos, F., Spahni, R., 2008. Rates of change in natural and anthropogenic radiative forcing over the past 20,000 years. Proceedings of the National Academy of Sciences 105 (5), 1425
1430. Khatun, F., Monir, M.M.U., Arham, S.M.N., Wahid, Z.A., 2016. Implementation of carbon dioxide gas injection method for gas recovery at rashidpur gas field, Bangladesh. International Journal of Engineering Technology and Sciences (IJETS) 5 (1), 52
61. Kovscek, A., 2002. Screening criteria for CO2 storage in oil reservoirs. Petroleum Science and Technology 20 (7
8), 841
866. Kumar, R., Pandey, S., Pandey, A., 2006. Plant roots and carbon sequestration. Current Science 91, 885
890. Littke, R., Zieger, L., 2020. Formation of organic-rich sediments and sedimentary rocks. Hydrocarbons, Oils and Lipids: Diversity, Origin, Chemistry and Fate. Springer, pp. 475
492. Liu, S., Agarwal, R., Sun, B., Wang, B., Li, H., Xu, J., et al., 2021. Numerical simulation and optimization of injection rates and wells placement for carbon dioxide enhanced gas recovery using a genetic algorithm. Journal of Cleaner Production 280, 124512. Manisalidis, I., Stavropoulou, E., Stavropoulos, A., Bezirtzoglou, E., 2020. Environmental and health impacts of air pollution: a review. Frontiers in Public Health 8, 14. Moghadasi, R., Rostami, A., Hemmati-Sarapardeh, A., 2018. Enhanced oil recovery using CO2. In: Bahadori, A. (Ed.), Fundamentals of Enhanced Oil and Gas Recovery from Conventional and Unconventional Reservoirs. Gulf Professional Publishing, pp. 61
99. Oldenburg, C.M., Benson, S.M., 2002. CO2 injection for enhanced gas production and carbon sequestration. In: SPE International Petroleum Conference and Exhibition in Mexico. Society of Petroleum Engineers. Oldenburg, C., Stevens, S., Benson, S., 2004. Economic feasibility of carbon sequestration with enhanced gas recovery (CSEGR). Energy 29 (9
10), 1413
1422. Pyo, K., Damian-Diaz, N., Powell, M., Van Nieuwkerk, J., 2003. CO2 Flooding in Joffre Viking Pool. In: Canadian International Petroleum Conference, Petroleum Society of Canada. Calgary, Alberta, p. 30. Qin, J., Han, H., Liu, X., 2015. Application and enlightenment of carbon dioxide flooding in the United States of America. Petroleum Exploration and Development 42 (2), 232
240. Ravanchi, M.T., Sahebdelfar, S., 2014. Carbon dioxide capture and utilization in petrochemical industry: potentials and challenges. Applied Petrochemical Research: A Journal of Science and its Applications 4 (1), 63
77. Ren, B., Ren, S., Zhang, L., Chen, G., Zhang, H., 2016. Monitoring on CO2 migration in a tight oil reservoir during CCS-EOR in Jilin Oilfield China. Energy 98, 108
121. Riding, J.B., Rochelle, C.A., 2009. Subsurface characterization and geological monitoring of the CO2 injection operation at Weyburn, Saskatchewan, Canada. Geological Society, London, Special Publications 313 (1), 227
256.

Sequestration of carbon dioxide into petroleum reservoir for enhanced oil and gas recovery

309

Satter, A., Iqbal, G.M., 2016. 17 - Enhanced oil recovery processes: thermal, chemical, and miscible floods. Reservoir Engineering. Gulf Professional Publishing, Boston, MA, pp. 313
337. Shiran, B.S., Skauge, A., 2013. Enhanced oil recovery (EOR) by combined low salinity water/polymer flooding. Energy & Fuels 27 (3), 1223
1235. Speight, J., 2020. Chapter 3
Reservoirs and reservoir fluids. In: Speight, J. (Ed.), Shale Oil and Gas Production Processes. Gulf Professional Publishing, pp. 139
220. Stallinga, P., 2019. Comprehensive analytical study of the greenhouse effect of the atmosphere. Atmospheric and Climate Sciences 10 (1), 40
80. Stein, T., Leskiw, M., 2000. Oxidant damage during and after spaceflight. American Journal of Physiology-Endocrinology and Metabolism 278 (3), E375
E382. Taber, J.J., Martin, F., Seright, R., 1997. EOR screening criteria revisited-Part 1: introduction to screening criteria and enhanced recovery field projects. SPE Reservoir Engineering 12 (03), 189
198. Tang, Y., Yang, R., Bian, X., 2014. A review of sequestration projects and application in China. The Scientific World Journal 2014, 381854. Tunio, S.Q., Tunio, A.H., Ghirano, N.A., El Adawy, Z.M., 2011. Comparison of different enhanced oil recovery techniques for better oil productivity. International Journal of Applied Science and Technology 1, 143
153. Van der Burgt, M., Cantle, J., Boutkan, V., 1992. Carbon dioxide disposal from coalbased IGCC’s in depleted gas fields. Energy Conversion and Management 33 (5
8), 603
610. Vega, B., Kovscek, A.R., 2010. 4
Carbon dioxide (CO2) sequestration in oil and gas reservoirs and use for enhanced oil recovery (EOR). In: Maroto-Valer, M.M. (Ed.), Developments and Innovation in Carbon Dioxide (CO2) Capture and Storage Technology, Vol. 2. Woodhead Publishing, pp. 104
126. Yoro, K.O., Daramola, M.O., 2020. CO2 emission sources, greenhouse gases, and the global warming effect. Advances in Carbon Capture. Elsevier, pp. 3
28. Zekri, A., Jerbi, K., 2002. Economic evaluation of enhanced oil recovery. Oil & Gas Science and Technology 57 (3), 259
267. Zhang, H., Nikolov, A., Wasan, D., 2014. Enhanced oil recovery (EOR) using nanoparticle dispersions: underlying mechanism and imbibition experiments. Energy & Fuels 28 (5), 3002
3009. Zhang, L., Ren, B., Huang, H., Li, Y., Ren, S., Chen, G., et al., 2015. CO2 EOR and storage in Jilin oilfield China: monitoring program and preliminary results. Journal of Petroleum Science and Engineering 125, 1
12. Zhou, X., Wang, Y., Zhang, L., Zhang, K., Jiang, Q., Pu, H., et al., 2020. Evaluation of enhanced oil recovery potential using gas/water flooding in a tight oil reservoir. Fuel 272, 117706. Zou, C., 2017. Unconventional Petroleum Geology. Elsevier.

Index Note: Page numbers followed by “f” and “t” refer to figures and tables, respectively.

A Attrition, 170
172

B Bioconversion of carbon source opportunity and challenges in, 82
85, 84t technical and economic aspects, 82
83 Bioconversion in circular bioeconomy importance of, 80
82 of insects and microalgae, 83f linear economy versus, 81f Biomethanation of CO2 by anaerobic digestion, 80 biological process results, 80 complex organic molecules, 80 of digestion process, 80

C Calcium looping (CaL) process carbonation conversion, 189 chemical reaction and diffusion stages, 166f cyclic CO2 capture in, 165f GM equation, 190
191 kinetics modeling of, 188
192 pre-combustion with, 168f technology of CaO-based sorbents, 167
172 kinetics modeling of, 188
192 natural and synthetic CaO-based sorbents, 172
188 process of, 164
167 CaO-based sorbents attrition, 170
172

calcium compounds, physical property of, 169t carbonation/calcination cycles, 170f impurity reaction, 170 reactivity decay of, 167
172 recarbonation step, 172f sintering, 168
169 Catalyst for hydrogenation alumina as, 138
140 of CO2 into methanol, 136
145 in CO2 using fixed-bed reactors, 146t mesoporous silica (SBA-15) as, 140
142 promoters, 142
145 supports, 138
142 preparation method calcination temperature role in, 223 challenges in, 221 hydrogen-TPD profiles for Ni, 220f impregnation technique of, 220
221 mesostructured fibrous zeolite support, 222
223 microemulsion and impregnation on, 222 Rh size distribution, 222f scanning electron microscopy, 224f via different techniques and conditions, 221
222 pretreatment, 145
147 promoters, 142
145 Catalytic conversion of CO2 into methanol activation and thermodynamic challenges for, 135
136 deactivation of, 153
154 factors affecting, 145
153 hydrogenation of, 136
145 uses and applications, 131
135 Chemical feedstock, 131
132

311

312

Index

Circular economic model for mitigation of CO2 emissions building design and technological innovations, 25 emissions from different processes, 25f greenhouse effects, 24 reduction of, 24
27 in shipping industry, 26 strategy and, 24
27 and sustainable utilization, 24
27 transport energy efficiency, 26 CO2 capture combustion processes, 9 fossil fuels, 5 higher reactivity of, 5
6 from large point sources, 4
5 with materials and methods, 8t of oxy-combustion, 9f oxy-fuel combustion, 7
9 polymeric and zeolite-based membranes using, 6 pre-combustion, 7 and storage technology, 4
9 technique of, 7 using alkaline solution, 6 and valorization technology carbon-based products market, 1
2 emissions, 3
4 Intergovernmental Panel on Climate Change (IPCC), 1
2 primary greenhouse gas, 1 and storage, 4
9 to valuable chemicals, 9
12 CO2 conversion into dimethyl ether one-step and two-step processes, 51f reactors types for, 53t into gasoline HHC chain reactions, 56 hydrocarbon ranges over zeolite catalysts, 57f hydrogenation reaction, 57f two stage reactor for, 55f to methane reaction catalyst synthesis scheme, 50f CH4 over Ag-doped N/TiO2 photocatalyst, 50f

CH4 production rate, 50f and H2 activation, 49f hydrogenation of, 48f into methanol, 39
43 catalyst for hydrogenation of, 42t Cu particles with ZnO, 41
43 with Cu/ZrO2 bifunctional catalyst, 41f formation of methanol, 40 methods, 38
39 into synthesis gas Boudouard reaction, 45 DRM, catalysts for, 47t dry reforming of methane, 44 formation of, 43
44 methane decomposition, 45 partial oxidation of methane, 44 steam reforming of methane, 44 syngas ratio (SR), based on, 44f technology into clean fuels to dimethyl ether, 51
55 to gasoline, 55
57 to methane reaction, 46
50 to methanol, 39
43 methods for, 38
39 to synthesis gas, 43
46 CO2 emissions coal, 4 from different sectors, 3f major emerging economy nations, 4 pathways for from different sectors, 20f electricity generation, 22
23, 24f in industrial processes, 21
22 overview of, 19
23 in residential and commercial building, 20
21 in transportation sector, 22, 23f power and industry sectors, 3 sources of, 3 vs world population by years, 5f CO2 gas injection, fundamentals of EOR/EGR surface infrastructure, 301
302, 302f multiple phases design, 301 sources of, 298
301 electricity/heat sector, 299

Index

fossil fuel combustion and usage, 299 industrial processes, 300
301 industrial sector, 300 land-use, 300 transportation sector, 300 CO2 valorization challenges overcoming, 31
32 to sustainable products, 31
32 Conventional petroleum reservoirs, 292 Conventional reservoirs, 292 Core-shell, 180
181

D Dry reforming of methane carbon types, 202 heterogeneous catalyst for, 203
212 modifiers, role of, 215
219 Oxo and Fischer-Tropsch processes, 202 precursor, role of, 227
228 preparation methods, 219
224 process conditions, effects of, 224
227 support material of catalyst, 212
215 Dry reforming reaction modifier role in CH4 and CO2 conversion with temperature, 217f promoters used for, 216t TPO contours for, 218f support for catalysts with, 213t CH4 and CO2 conversion efficiency for, 214f

E Enhanced oil/gas recovery, 296
297 technology CO2 injection for, 302
305 CO2 solubility in, 305 EOR applications, 304t facility and process design, 305 optimum conditions for, 302
303 EOR technique, 292

F Factors affecting methanol synthesis catalyst pretreatment, 145
147

313

reaction conditions, 148
153 space velocity, 152
153 temperatures and pressures on catalysts, 148
151, 151t

G Gasification, 237 Gas recovery mechanism advanced oil and, 295
297 challenges and strategy for increasing, 297 by chemical EOR technology, 295 enhanced, 297 extraction of, 296f Gas reservoirs economic viability, 294 oil and, 293
294, 293f petroleum, 294 recoverable oil and, 293
294 sandstone and carbonate formations, 293
294 Global greenhouse gas emissions, 237
238 Greenhouse gas, 237
238

H Heterogeneous catalyst for dry reforming bimetallic, 208
212, 210t CH4 conversion, 206f CO2 conversion on, 206f CoMgoO, 207f noble metal-based, 203
206, 204t nonnoble metal-based, 206
208, 209t time vs CH4, 207f HyPr-RING, 167

I Industrial applications of SCCO2 advantages of, 244 bioactive compounds, extraction of, 240
242 biomass pretreatment, 246
247 cannabinoids, extraction of, 242
243 Cannabis sativa, 242 catalysis, 244
245

314

Index

Industrial applications of SCCO2 (Continued) conventional extraction methods, 240
241 with conventional solvent extraction, 241
242 for recovery of bioactive compounds, 241t C. sativa, harvesting and processing of, 242
243 green solvent, acts as, 246
247 for microorganism inactivation, 249t microwave-assisted technology, 243 power cycles, 246 as pretreatment method, 247 solubility of, 243 study on, 250 supercritical fluid extraction, 240
241 sustainable energy generation, 245
246 thermodynamic cycles using, 244 unique property of, 238
240 use of, 245 value-added biochemicals, recovery of, 246
247 waste heat into power, conversion of, 243
244 Industrial methanol synthesis, 132
133 Inorganic membranes carbon molecular sieve, 274
276 ceramic, 276
278 CMS, structural property of, 276f gas separation performances, 279
280 in-situ synthesis and secondary growth methods, 279 porous support of zeolite, 280 pyrolysis method, 275 YSZ ceramic hollow fiber support, 278f zeolite, 279
281 of zeolite, 279 zeolite/microporous structures, 280f Isotropic heterogeneous polymers, 270
271

L Liquefaction, 237

M Membrane preparation of inorganic, 267
269 chemical vapor deposition, 269 pyrolysis, 269 slip casting, 267 sol-gel process, 267
269, 268f of polymeric, 264
267 non-solvent induced phase, 265
266 phase inversion technique, 264
265 thermally induced phase separation, 266
267, 266f Membrane technology for CO2 capture and separation inorganic, 274
281 polymeric, 269
274 preparation of, 264
269 transport mechanisms for gas, 260
264 Mesoporous silica, 140
142 Methanol economy, 131 Methanol uses and application, 131
135 chemical feedstock, 131
132 energy source, 132 hydrogenation of CO2 into, 133
135 formation, 134 reverse water-gas shift reaction, 134 industrial synthesis, 132
133

N Natural and synthetic CaO-based sorbents cyclic performance of, 186f homogeneous distribution of stabilizer in, 188f natural sorbents, 173
181 chemical pretreatment, 177
179 doping of, 174
177 sintering-resistant supports, 179
181 of Rheinkalk limestone, 182f synthetic sorbents, 181
188 CaO-based, 184
188 derived calcium acetate, 183f derived calcium hydroxide, 183f unsupported, 182
184 Tammann temperature, 185t and undoped Longcliffe limestone, 177t Natural sorbents, 173
181

Index

O Oil and gas reservoirs, 293
294 Organic base-mediated fixation of CO2 and 2-ABNs, 118f and 2-aminobenzonitriles, 117t assembly of imidazo-pyridinones from, 114f carbon capture and storage (CCS), 94
95 carbon capture and utilization (CCU), 94
95 carboxylation of oacetamidoacetophenone with, 115
116, 116f carboxylic acids and ester derivatives, 109
111 derived azoles over organic bases, 112f five-membered heterocycles, 111
114 gluconic anhydrides from 2-butenoates, 119f hydroboration of BH3NH3 with, 109f hydroxybromination and carboxylation, sequence of, 101 isocyanate-free productions of polyureas, 103
104 linear/cyclic carbamates, 97
98 carbonates, 98
103 urea and carbamoyl azides, 95
97 of organocatalysts in synthetic chemistry, 95 polyureas-polycarbonates, 103
105 with propargyl alcohols and external nucleophiles, 103f and propylene oxides, 100f reduction-derived products, 105
109 six-membered heterocycles, 114
120 TBD-mediated synthesis of aminals from, 107f transformation, 114
115 into value-added products, 95
120 Oxygen carriers, 163

P Peptization, 267
268 Petroleum reservoir for enhanced oil and gas recovery advanced mechanism, 295
297

315

economic evaluation, 305
306 gas injection, fundamentals of, 297
302 reservoirs, 293
294 technology for, 302
305 Phase separation, 264 Photoautotrophic microalgae, 68
69 Polymeric membranes based on polyimide, 276f blends, 269
273 Fox equation, 271 mixed matrix, 273
274 MMMs fabrication, 273
274 overview of, 270f phase behavior of, 270
271 sieve materials, 274 Polymer production, 11
12 Precursor role in dry reforming process, 227
228 Primary energy sources, 291
292 Process conditions on dry reforming biogas, sources of, 227 calcination temperature affecting, 225 of multiwalled carbon nanotubes (MWCNTs), 225 pretreatment and calcination temperature, effects of, 226 reduction temperature in, 226

R Recovery factor, 295

S Sintering, 168
169 Slip casting, 267 Solvent, 265 Space velocity, 152
153 Supercritical fluids, 238 Sustainable utilization of CO2 on circular economy, 27f hydrocarbon and biomass reforming of, 28
29 to syngas, 28f hydrogenation to renewable fuels, 29
31 processes for, 27
31 renewable fuel, 30f

316

Index

Sustainable utilization of CO2 (Continued) toward circular economy challenges of, 31
32 global emissions of, 19f greenhouse gases emitted into atmosphere, 18f growth of, 17
18 industrial processes, 17 integration of, 19 pathways for emissions, 19
23 for value-added products, 27
31 Syngas, 43 Synthetic sorbents, 181
188

T Tammann temperature, 185t Tertiary oil recovery, 296 Thermodynamic challenges for methanol reduction, 135
136 Transport mechanisms for gas separation model assumptions, 262
263 nonporous membranes, diffusion in, 262
264 permeability and selectivity parameters, 263 polymeric membranes, 263
264 porous membranes, diffusion in, 261
262 solution-diffusion model, 262f

U Undoped Longcliffe limestone, 177t Unique property of SCCO2 CO2 with constant density lines, 239f of pure components, 239t Upcycling of carbon by insect larvae farming and processing, 77f fatty acid component, 79t GHG emissions of foods, 75f H. illucens, bioprocess technology for, 77
78 insect farming, advantages of, 76
77

of organic waste to energy, 78f from waste via bioconversion into biofuel by anaerobic digestion, 80 in circular bioeconomy, 80
82 by insect larvae, 72
79 by microalgae, 66
72 opportunity and challenges in, 82
85 Upcycling of CO2 by microalgae an alternative protein, 69
72 bioconversion of, 67 bioethanol from, 69 for biofuel and feed, 68f biomasses of, 67
68 biomass via photosynthesis, 67 bioprocess of converting, 67 as carbon source for biotechnical application, 70t Chlorella and Spirulina, nutritional profile of, 73t conversion bioprocess of, 67 fatty acid component derived from algae strains, 71t fermentation of, 69 photoautotrophic, 68
69 strains of, 69

V Vacuum substitute, 295 Valorization of CO2 copolymerization of, 11
12 enhanced oil recovery, 10
11 methanol production, 10 petrochemical industry, 11
12 photocatalytic conversion of, 11 to produce valuable chemicals, 9
12 recycling and utilization, 9 using electrochemical conversion pathway, 9
10

W Waste-to-energy conversion processes, 237 Waste upcycling, 66