Alternative catalysts for the high-temperature H2O/CO2 co-electrolysis to syngas
N. Bogolowski, B. Sánchez Batalla, B. K. Shin, J.-F. Drillet
Proceedings 13th European SOFC & SOE Forum, Ch 3 (2018),A0808 link to pdf
Nickel is the most common cathode material for H2O/CO2 co-electrolysis. Main challenges are related to stability in presence of large amount of water vapour and to carbon formation that can lead to degeneration and destruction of the cathode material. Alternative catalyst materials like Ni3Sn2 and La0.75Sr0.25Cr0.5Mn0.5O3-δ perovskite (LSCrM) were synthesized and tested regarding their activity for reverse water - gas shift reaction (RWGS) in a tube reactor under different hydrogen/carbon dioxide atmospheres at 700°C and 800°C and ambient pressure. Reaction products were detected by a humidity sensor and gas chromatography. Both catalysts were found to be active for the RWGS reaction. At reactor outlet, maximal CO molar ratio of 0.23 and 0.22 was collected with LSCrM and Ni catalysts at 0.5:0.5 H2 :CO2 molar ratio, respectively independently of temperature value. Surprisingly, highest CO rate value of 0.17 was obtained at 0.25:0.75 H2:CO2 molar ratio and 800°C. The catalyst stability was evaluated during 300 h long - term experiments under different gas atmospheres. LSCrM showed stable redox behaviour whereas Ni3Sn2 was subjected to slight phase segregation into NiO and SnO2. No carbon was detected at all catalysts.