Boosting CO2 hydrogenation to methanol by adding trace amount of Au into Cu/ZnO catalysts

Boosted CO 2 hydrogenation to methanol was achieved by introducing appropriate amount of Au into conventional Cu-based catalysts. The Au x Cu/ZnO bimetallic catalysts with various Au/Cu molar ratio (x = 0.001, 0.005, 0.02 and 0.05) were prepared by the co-precipitation method, among which the Au 0.005 Cu/ZnO catalyst exhibited the highest methanol production rate. The formation of Au-Cu alloy was identified on the Au x Cu/ZnO bimetallic catalysts. Experimental characterizations and density functional theory (DFT) calculations suggested metal-oxide interfaces with oxygen vacancies as intrinsic active sties for both un-promoted and Au-promoted Cu/ZnO catalysts. The promotion effect of Au in bimetallic catalysts was correlated with the increase of active sites, facilitation of CO 2 activation and modification of intermediate adsorption. The present work for the first time develops a promising Au 0.005 Cu/ZnO bimetallic catalyst with trace amount of Au (only 0.4 wt%) and provides insight into the reaction mechanism over Au-promoted Cu/ZnO catalysts for methanol synthesis via CO 2 hydrogenation.