Microwave plasma setups for CO₂ conversion: A mini-review

Abstract

Global warming poses one of the most critical challenges of the 21st century, leading to significant environmental damage. The extraction and combustion of fossil fuels release substantial amounts of greenhouse gases, thereby contributing to climate change. In response to this pressing issue, plasma-based conversion of carbon dioxide has emerged as a prominent and widely explored solution. Among the various plasma technologies, microwave plasma setups have garnered considerable attention due to their exceptional ability to decompose carbon dioxide, facilitate the dry reforming of methane and reverse water gas shift. These setups are renowned for their high degree of ionization and generation of non-equilibrium plasma, making them a clean and highly efficient method for treating greenhouse gases. However, researchers often face challenges in selecting the appropriate microwave plasma reactors. Thus, the primary objective of this paper is to provide guidance on microwave plasma setups. It is achieved by illustrating experimental configurations based on the microwave operating mechanism and presenting a classification of microwave plasma sources according to their operating principles. Moreover, specific experimental operations are discussed within the scope of our analysis, offering valuable insights to researchers in this field.

Keywords

Microwave plasma / Experimental setups / CO₂ reactions / Cooling methods

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was financially supported in part by the National Key Research and Development Program of China(Grant No. 2023YFB4603500), in part by the National Natural Science Foundation of China (Grant No. 62001130), in part by the Guizhou Science and Technology Plan from Guizhou Provincial Department of Science and Technology (Grant No. QKHJC-ZK [2021] 297), in part by the Guizhou Province High-Level Innovative Talent Program (Grant No.GCC [2023]004), in part by Guiyang University under Grant GYU-KY-(2023). We would like to acknowledge the valuable contributions and support from various individuals and organizations throughout the research process. We are grateful to Kim et al. for granting permission to use the figures from their paper “Carbon dioxide conversion in an atmospheric pressure Microwave plasma touch: Improving efficiencies by enhancing afterglow quenching”. We are grateful to D'Isa et al. for granting permission to use the figures from their paper “Performance analysis of a 2.45 GHz microwave plasma torch for CO2 decomposition in gas swirl configuration”. We are grateful to Uhm et al. for granting permission to use the figures from their paper “Carbon dioxide elimination and regeneration of resources in a microwave plasma torch”. We are grateful to Mohsenian for granting permission to use the figures from their paper “Carbon dioxide conversion by solar-enhanced microwave plasma: Effect of specific power and argon/nitrogen carrier gases”. We are grateful to Vesel et al. for granting permission to use the figures from their paper “Dissociation of CO2 molecules in microwave plasma”. We are grateful to Chen et al. for granting permission to use the figures from their paper “Plasma assisted catalytic decomposition of CO2”. We are grateful to Chun et al. for granting permission to use the figures from their paper “CO2 Microwave Plasma-Catalytic Reactor for Efficient Reforming of Methane to Syngas” and “Reforming of methane to syngas in a microwave plasma torch at atmospheric pressure”. We are grateful to Below et al. for granting permission to use the figures from their paper “Carbon dioxide dissociation in a microwave plasma reactor operating in a wide pressure range and different gas inlet configurations”. We are grateful to Mansfeld for granting permission to use the figures from their paper “Conversion of carbon dioxide in microwave plasma torch sustained by gyrotron radiation at frequency of 24 GHz at atmospheric pressure”. We are grateful to Qin et al. for granting permission to use the figures from their paper “Conversion of CO2 in a low-powered atmospheric microwave plasma: In-depth study on the trade-off between CO2 conversion and energy efficiency”. We are grateful to Carbone et al. for granting permission to use the figures from their paper “Spatio-temporal dynamics of a pulsed microwave argon plasma: ignition and afterglow”. We are grateful to Van Alphen et al. for granting permission to use the figures from their paper “Modelling post-plasma quenching nozzles for improving the performance of CO2 microwave plasmas”. The inclusion of these figures has greatly enhanced the clarity and effectiveness of this work.

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