Inhomogeneities in the Catholyte Channel Limit the Upscaling of CO2 Flow Electrolysers

Joseph W. Blake*, Vojtěch Konderla, Lorenz M. Baumgartner, David A. Vermaas, Johan T. Padding, J. W. Haverkort

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

8 Citations (Scopus)
48 Downloads (Pure)

Abstract

The use of gas diffusion electrodes that supply gaseous CO2 directly to the catalyst layer has greatly improved the performance of electrochemical CO2 conversion. However, reports of high current densities and Faradaic efficiencies primarily come from small lab scale electrolysers. Such electrolysers typically have a geometric area of 5 cm2, while an industrial electrolyser would require an area closer to 1 m2. The difference in scales means that many limitations that manifest only for larger electrolysers are not captured in lab scale setups. We develop a 2D computational model of both a lab scale and upscaled CO2 electrolyser to determine performance limitations at larger scales and how they compare to the performance limitations observed at the lab scale. We find that for the same current density larger electrolysers exhibit much greater reaction and local environment inhomogeneity. Increasing catalyst layer pH and widening concentration boundary layers of the KHCO3 buffer in the electrolyte channel lead to higher activation overpotential and increased parasitic loss of reactant CO2 to the electrolyte solution. We show that a variable catalyst loading along the direction of the flow channel may improve the economics of a large scale CO2 electrolyser.

Original languageEnglish
Pages (from-to)2840-2852
JournalACS Sustainable Chemistry and Engineering
Volume11
Issue number7
DOIs
Publication statusPublished - 2023

Keywords

  • CO reduction
  • electrolysis
  • gas diffusion electrode
  • parasitic reactions
  • scale up
  • variable catalyst loading

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