Effects of metal cation doping in CeO2 support on catalytic methane steam reforming at low temperature in an electric field

Catalytic methane steam reforming was conducted at low temperature using a Pd catalyst supported on Ce1-xMxO2 (x = 0 or 0.1, M = Ca, Ba, La, Y or Al) oxides with or without an electric field (EF). The effects of the catalyst support on catalytic activity and surface proton hopping were investigated. Results show that Pd/Al-CeO2 (Pd/Ce0.9Al0.1O2) showed higher activity than Pd/CeO2 with EF, although their activity was identical without EF. Thermogravimetry revealed a larger amount of H2O adsorbed onto Pd/Al-CeO2 than onto Pd/CeO2, so Al doping to CeO2 contributes to greater H2O adsorption. Furthermore, electrochemical conduction measurements of Pd/Al-CeO2 revealed a larger contribution of surface proton hopping than that for Pd/CeO2. This promotes the surface proton conductivity and catalytic activity during EF application.