Surface composition and catalysis by alloys: on the relevance of surface science to catalysis

Abstract

It is to be regretted that only few catalysts have been studied from the point of view of “materials science”. Nevertheless, important information can be obtained on the function of catalysts when, for example, the surface composition of multicomponent catalysts is determined using surface science tools. Two examples of such investigations are discussed: PdAg alloys and NiCu alloys. The data on PdAg alloys show that the vibrational spectra of CO and possibly also the catalytic behaviour of the alloys can be explained by the dilution of palladium in silver, i.e. by essentially “geometrical” effects. The data on NiCu alloys show that the Fischer-Tropsch synthesis of hydrocarbons is a reaction that requires ensembles of several active atoms to occur.