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

Abstract

CO, CO2 and CO–CO2 mixed gas were electrochemically decomposed at 800°C using a cell of Ni–YSZ (8mol% yttria-stabilized zirconia) cathode (5mm thick), dense YSZ electrolyte (40μm thick) and Ru–YSZ anode (30μm thick). The decomposition rate of CO gas (2CO→2C+O2) was in the range of 9–15% at an applied voltage of 1.0V and increased to 67–100% at 2.0–8.0V. 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 6–8vol% was converted to CO (6–8vol%), O2 (2–9vol%) 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 2–10vol% 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).