Methane production via direct CO₂ electrolysis: A modelling study

This paper presents an analysis of CH4 production via CO2 electrolysis, which could be a promising hydrogen carrier production method. An original process model, that takes into account the multi-product nature of CO2 reduction and the carbonation phenomenon, was used and validated against experimental data. The energy efficiency of the reactor reaches 24% at CH4 selectivity of 63%. The relatively low efficiency is largely due to the cathode overpotential. It was found that the maximum single-pass conversion (SPC) is 18.5% for an alkaline electrolyte, which is due to intense carbonation. It was also found that reducing its intensity by using an acidic electrolyte can be beneficial. These include no need for electrolyte regeneration, an increase in outlet methane concentration (from 27 to >[jls-end-space/]35%), an increase in max. SPC (from 18.5 to 100%), and better CO2 availability. However, modern acidic catalysts are characterized by lower performance compared to their alkaline counterparts.