Computational fluid dynamic modelling of electrochemical reactor for CO 2 conversion to ethylene Ashween Virdee and John Andresen Heriot-Watt University, UK Transitioning away from fossil fuels to minimize greenhouse gas emissions while maintaining energy security is essential. Utilizing renewable energy to convert captured carbon dioxide into chemicals and fuels is receiving significant attention, as it can curb emissions and create valuable products. Notably, it is estimated that large- scale deployment of carbon capture and utilization (CCU) has the potential to decouple the production of chemicals and fuels from fossil fuels resulting in a reduction of 3.5 Gt CO 2 -eq by 2030. 1 Currently, a wide range of technologies are being researched on for direct electro-reduction of CO 2 to produce a variety of chemicals (e.g., methanol, ethanol, ethylene, acetic acid). Ethylene is a vital chemical precursor for many industrial processes, with a market value of $260 billion in 2020 and a rising demand expected from 180 to 250 Mtpa between 2017 and 2025. 2 3 Large-scale direct electrochemical reduction of CO 2 to ethylene still suffers challenges due to carbonate formation during the reaction resulting in parasitic loss of CO 2 , high electrolyte, and energy consumption. Thus, the technology readiness level of CO 2 electro-reduction is still low (between 2- 4). 4 To improve the efficiency of producing C 2+ products, our cutting-edge approach is a tandem reaction system in separate electrolysers. The first step involves electrochemical reduction of CO 2 to CO. Subsequently, the syngas (i.e., CO and H 2 ) undergoes electrochemical reduction to desired C 2+ products. The reduction of CO 2 to CO has been successfully demonstrated with state-of-the-art technologies displaying high faradaic efficiencies (>90%). However, the conversion of CO to ethylene has lower faradaic efficiencies, and the reported values vary significantly (37% – 78%) depending on the electrolyser set-up. 3,5 Herein, we focus on advancing our understanding of the effect of process conditions for the electro-reduction of syngas to ethylene using computational fluid dynamic (CFD) modelling of the state-of-the-art continuous flow three-compartment cell. A 3-dimensional model of the electrochemical cell is developed using COMSOL Multiphysics software, considering the electrochemical reactions at the electrodes, current conduction, fluid flow, and the transport of the charged and neutral species. After successful validation, the model is used to optimize the system efficiency by investigating the electrochemical cell design and operating conditions enabling pilot-scale implementation. References 1. A. Kätelhön, R. Meys, S. Deutz, S. Suh and A. Bardow, Proc Natl Acad Sci U S A , 2019, 116 , 11187–11194. 2. Wood Mackenzie, Ethylene Global Supply Demand Analytics Service | Wood Mackenzie, https://www.woodmac.com/ja/ news/editorial/ethylene-global-supply-demand-analytics-service/, (accessed 10 November 2022).H. P. Duong, N. H. Tran, G. Rousse, S. Zanna, M. W. Schreiber and M. Fontecave, ACS Catal , 2022, 12 , 10285–10293. 3. J. A. Rabinowitz and M. W. Kanan, Nature Communications 2020 11:1 , 2020, 11 , 1–3.J. 4. Li, A. Xu, F. Li, Z. Wang, C. Zou, C. M. Gabardo, Y. Wang, A. Ozden, Y. Xu, D. H. Nam, Y. Lum, J. Wicks, B. Chen,, T. K. Sham, B. Zhang, E. H. Sargent and D. Sinton, Nature Communications 2020 11:1 , 2020, 11 , 1–8.
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