Heterogeneous Catalysis at an Atomic Scale

摘要

For the overwhelming majority of processes in modern chemical and petrochemical industry, the presence of an active and selective catalyst is crucial. In the, USA the total value of products from catalytic processes has been estimated to be roughly 9·10~(11) $ per year, corresponding to 17% of the GNP. An arsenal of modern methods enables the physical chemist to characterize active sites and chemisorption complexes; quantum chemical calculations increasingly lead to concrete predictions. The key issue remains, however, to unravel reaction mechanism and to use this knowledge for the design of superior catalysts. In the present paper some challenging problems are addressed: (1) How does a "promoter" in a Rh/NaY catalyst direct CO hydrogenation towards synthesis of ethanol and ethyl acetate? (2) How does NO_x decompose over Cu/ZSM 5 catalysts and how is its reduction to N_2 enhanced by O_2? (3) How does the isomerization of butane to isobutane avoid primary carbenium ions over some acid cata- lysts, why are other catalysts with stronger acid sites less active?