CORRELATION BETWEEN SURFACE-STRUCTURE AND REACTION-MECHANISMS - REACTIONS OF OLEFINS ON NICKEL AND PALLADIUM FILMS

Reactions of cis-but-2-ene have been investigated in the presence of C3D6 or D2 on nickel and palladium films treated in different ways. Condensing the films at 470 °C instead of 0 °C reduces drastically the extent of exchange and the formation of highly deuteriated isomers. Treatments by hydrogen at 0 °C of the palladium films condensed at 470 °C restore almost entirely the properties of the unsintered films. It is suggested that some specific sites of low coordination number, such as corners or isolated adatoms, are responsible for all the reactions involving dissociative adsorption, and that the defects are erased by thermal treatment and reconstructed by exposure to hydrogen via hydride formation. © 1979.