STRUCTURE AND FUNCTION OF REAL CATALYSTS.

This paper addresses issues such as the relation between the physical and chemical nature of active centers, activation of reactant molecules, mechanisms of catalytic reactions and distribution of promoters in real catalysts. Most of the examples given in this paper are based on the results from the author's laboratory concerning the activity and selectivity of Cu-ZnO catalysts for the hydrogenation of carbon monoxide and carbon dioxide, the water gas shift reaction, and some reactions of amines. Evidence for the interactions between the copper and zinc oxide is presented which is then analyzed in terms of defect equilibria using models and constants partially known from the literature and adapted for the present system. It is shown on the basis of boundary layer theory for small particles that charge transfer between copper metal particles, also present in the system, and the zinc oxide phase is insignificant. On the other hand, electron equilibria between the solute copper species and the zinc oxide matrix are dictated primarily by intrinsic ionization Cu**0 yields Cu** plus plus e** minus and oxygen vacancy formation. Optical absorption spectroscopy strongly corroborates the theoretical contention that a significant portion of the copper is in electron deficient state, and there is some evidence based on Auger spectroscopy for the presence of Cu** plus species on the catalyst surface.