Methanol steam reforming behavior of copper impregnated over CeO2–ZrO2 derived from a surfactant assisted coprecipitation route

Abstract

A series of ceria-zirconia solid solutions has been prepared by a surfactant assisted coprecipitation method. After impregnation of copper, their activities have been assessed for methanol steam reforming. The results indicate that the compositions with 10 and 15 at.% loading of copper on Ce0.6Zr0.4O2 exhibit maximum catalytic efficiency. Detailed structural analyses reveal high degree of copper dispersion on the ceria-zirconia matrix. In situ XPS studies confirm reduction of surface CuO species with concomitant lowering of Cu-surface atomic composition and increase of carbon. These evidences point to the formation of large aggregates of copper covered with coke that is suggested to be responsible for on stream activity loss. On regeneration, these aggregates break into a mixture of oxidized (Cu2+) and reduced (Cu0 and Cu+) copper species showing similar activity to the as prepared catalysts. In general, we have attributed catalytic activity to different proportions of copper components in the various forms of these catalysts.