Strong Metal-Support Interactions

Studies of metal-support interactions have yielded significant progress in the past few years. It is appropriate, at the outset of the Metal-Support Interaction symposium, to review our current state of knowledge. We will focus on those facts that seem firmly established as well as on the major items that remain controversial. A brief synopsis of the older literature will be given first. The finding that the chemisorption properties of Group VIII metals are drastically altered by titania supports following high-temperature-reduction (1), later generalized to include other reducible transition metal oxides (2), was interpreted to mean that a strong interaction occurred between these phases. A theoretical model (3) indicated covalent bonding between a Ti3+ cation and a Pt atom and further suggested that cation-to-metal charge transfer would strengthen the interaction. This electronic perturbation of the metal atoms was held responsible for the suppressed chemisorption of H2 and CO, although the