Electrochemical conversion of methane to ethylene, olefins, and paraffins using metal-supported solid oxide cells
Electrochemical oxidative coupling of methane (E-OCM) with Sr2Fe1·5Mo0·5O6−δ (SFM) catalyst is demonstrated with metal-supported solid oxide cells (MS-SOC). SFM anode and Pr6O11 cathode catalysts are loaded into a porous symmetric-architecture cell by infiltration and firing. The most effective chelating agent (citric acid/ethyl glycol) and optimal firing/reducing temperatures (850 °C/750 °C) for the SFM catalyst precursor solution are selected and confirmed by cell testing. Operating temperature, cell voltage, and oxygen concentration at the cathode greatly affect the methane conversion rate and product selectivity by controlling the oxygen ion flow. CH4 conversion of 85.8% is obtained, with C2H4, C2H6, and H2 concentrations of 10.5%, 12.3%, and 25.6% at 800 °C, respectively, in the product exhaust gas. Reasonable stability of the current density and methane conversion is demonstrated during 200 h operation. This research demonstrates technical progress in catalyst and device development for the E-OCM reaction to synthesize valuable chemicals.