XPS studies of Cu/ZnO/Al2O3 ultra-fine catalysts derived by a novel gel oxalate co-precipitation for methanol synthesis by CO2+H2

The chemical states of Cu and Zn in an ultra-fine high performance Cu/ZnO/Al2O3 catalyst at various preparation stages for the methanol synthesis by CO2/H-2 were investigated by X-ray photoelectron spectroscopy. It was found that copper was presented as metallic state and zinc still as ZnO during reaction or reduction. Moreover, it shows that the metallic Cu can be partially oxidized to Cu6+ species by pure CO2. The active center of the Cu/ZnO/Al2O3 catalyst for methanol synthesis was discussed. (C) 2001 Elsevier Science B.V. All rights reserved.