Syngas production through CH4-assisted co-electrolysis of H2O and CO2 in La0.8Sr0.2Cr0.5Fe0.5O3-δ-Zr0.84Y0.16O2-δ electrode-supported solid oxide electrolysis cells

Abstract

High temperature co-electrolysis of H2O/CO2 allows for clean production of syngas using renewable energy, and the novel fuel-assisted electrolysis can effectively reduce consumption of electricity. Here, we report on symmetric cells YSZ-LSCrF | YSZ | YSZ-LSCrF, impregnated with Ni-SDC catalysts, for CH4-assisted co-electrolysis of H2O/CO2. The required voltages to achieve an electrolysis current density of −400 mA·cm−2 at 850 °C are 1.0 V for the conventional co-electrolysis and 0.3 V for the CH4-assisted co-electrolysis, indicative of a 70% reduction in the electricity consumption. For an inlet of H2O/CO2 (50/50 vol), syngas with a H2:CO ratio of ≈2 can be always produced from the cathode under different current densities. In contrast, the anode effluent strongly depends upon the electrolysis current density and the operating temperature, with syngas favorably produced under moderate current densities at higher temperatures. It is demonstrated that syngas with a H2:CO ratio of ≈2 can be produced from the anode at a formation rate of 6.5·mL min−1·cm−2 when operated at 850 °C with an electrolysis current density of −450 mA·cm−2.