Methanation of CO₂ on Cu in a tubular co-ionic SOEC

This work aims contributing to develop a cathode for CO2 methanation in tubular co-ionic (H+/O2- conducting) SOECs and to cell operation optimization to decrease energy input and costs for advancing process application. It studies the effect of temperature (325-550 degrees C) and potential (from -2 to +2 V at 450 degrees C) on CO2 conversion and selectivity to CH4 and CO, at bench scale, at atmospheric pressure and using high flowrates (42 NL/h) and realistic compositions (4H(2)/CO2 binary mix), over a Cu film (<2 mu m) coated by electroless on an anode (Ni-BZCY)-supported solid electrolyte (BZCY) candle. CH4 preferentially forms over CO. CH4 selectivity increases with temperature up to 97.3% at 400 degrees C, from which, CH4 and CO selectivity decreases and increases, respectively. The optimum potential is -0.5V, as maximizes CH4 selectivity (94.2%) and minimizes energy cost (0.002 kWh/kg CH4) with high CO2 conversion (32.5%) and low CO selectivity (5.8%), resulting in higher CH4 yield and lower CH4 purification cost.(c) 2023 The Authors. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).