Novel approach to integrate CO2 utilization coupled with direct methane conversion to C2 products using solid oxide electrolysis cell

Abstract

Solid oxide electrolysis cells (SOECs) based on oxygen ion-conducting electrolytes driven at high temperatures have been considered promising candidates for CO2 utilization and energy storage to mitigate environmental problems because of their high current density and efficiency. Additionally, SOECs have potential to integrate with processes that require high-temperature pure oxygen produced at anode and CO2 utilization at cathode. Despite this advantage, CO2 utilization via SOEC has been extensively studied only for the practical use and development of CO2 electrolysis electrodes. In this study, we propose novel strategy that synergistically integrates both CO2 electrolysis and OCM in single apparatus. A previous study on OCM using SOEC resulted in low C-2 yield, highlighting the difficulty to develop anode electrode that satisfies the MIEC property to promote the oxygen evolution reaction as well as the catalytic activity to improve CH4 conversion and C-2 selectivity. Herein, CO2 electrolysis coupled with the OCM reaction (C-2 yield of 25.4% at 825 degrees C) was achieved through reactor capable of independently controlling operating conditions of two reactions in one apparatus. Furthermore, thermodynamic simulation analysis demonstrated that the conversion efficiency of the proposed OCM-SOEC system is superior to that of the conventional OCM-air separation unit (ASU) system.