Model Cu/ZnO Catalysts for Methanol Synthesis: The Role of Surface Structure. Progress Report.

摘要

Catalysts based on CuO/ZnO mixtures are well known for their activity and selectivity in the methanol synthesis reaction (CO + 2H(sub 2) (yields) CH(sub 3)OH). These catalysts are also widely used for water-gas shift (CO + H(sub 2)O (l reversible) CO(sub 2) + H(sub 2)), which occurs together with methanol synthesis under most conditions, there still remains a considerable controversy over the nature of the active sites and the relationship between surface structure and catalyst activity. Previous research on these catalysts have been in two areas: (1) kinetic studies of high-surface-area Cu/ZnO catalysts under realistic reaction conditions and their subsequent structural characterization, and (2) surface science studies on well-defined surfaces of Cu and ZnO single crystals, where adsorption and desorption processes of the reactants and products have been characterized under ultra high vacuum (uhv) conditions. The goal of our research project is to help bridge the gap between these two disparate bodies of research. We thus are attempting to correlate reaction kinetics made at medium-pressure conditions (<10 atm.) on well-defined single-crystal surfaces with: (1) kinetics at similar conditions on high surface area Cu/ZnO catalysts, (2) details of the atomic-level surface structure, and (3) information on adsorption/desorption phenomena available from uhv surface science studies.