Elucidation of Structure-Function Relationships in Catalysis

Over the past 10 years, a number of groups have become active in applying these experimental techniques to clarify the relationships between atomic-level surface structural-compositional properties and the 

Structural Sensitivity The Dependence of Catalytic Activity and Selectivity on Crystal-Surface Orientation 

It has long been known that catalytic reaction rates and selectivity can depend sensitively on the size of catalyst particles (37-39). Such structural sensitivity has generally been explained by models whereby the activity or selectivity of the reaction was assumed to vary markedly with the local geometry of the surface sites. Using the methods outlined above, it has now been unequivocally proved that, indeed, many steady-state high-pressure catalytic reactions depend sensitively on the crystal-surface orientation of the model catalysts, and that others do not. This subject has been recently reviewed by Boudart (40), who points out the potential utility of single-crystal surfaces as standards against which to compare industrial catalysts. 

Since the isomerization of n-alkenes (six carbon atoms or longer) is believed to involve a methylcyclopentane (MCP) intermediate in C6 iso- 

Garin et al. (58) also compared the contact reactions of C6 hydrocarbons over several Pt single crystals, foils, and supported catalysts. They found that isomerization by bond-shift or cyclic mechanisms and hydro-genolysis over crystalline Pt surfaces simulate well data for supported Pt of large Pt cluster size, and that isomerization by bond shift is more important when the surface is stepped. 

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