Decomposition of carbon monoxide and carbon dioxide using cathode-supported dense yttria-stabilized zirconia electrolyte cell

CO, CO2 and CO-CO2 mixed gas were electrochemically decomposed at 800 °C using a cell of Ni-YSZ (8 mol% yttria-stabilized zirconia) cathode (5 mm thick), dense YSZ electrolyte (40 μm thick) and Ru-YSZ anode (30 μm thick). The decomposition rate of CO gas (2CO→2C+O2) was in the range of 9-15% at an applied voltage of 1.0 V and increased to 67-100% at 2.0-8.0 V. Carbon was deposited significantly near the electrolyte interface in the cathode. In the case of CO2 gas decomposition (2CO2→2CO+O2, CO2→C+O2), CO2 gas of 6-8 vol% was converted to CO (6-8 vol%), O2 (2-9 vol%) and C. Deposition of a small amount of C was observed in the cathode. The decomposition of CO-CO2 mixed gas produced O2 gas of 2-10 vol% in the anode but carbon deposition hardly occurred. Carbon deposited in the cathode from CO decomposition was easily oxidized to CO gas again by CO2 mixed (C+CO2→2CO).