Bonding and reactivity of styrene on Cu(110): heterogeneous alkene epoxidation without the use of silver

Styrene adsorption on oxygenated Cu(110) has been studied by temperature programmed reaction, fast XPS and NEXAFS. When the molecule is adsorbed on Cu metal sites in the presence of co-adsorbed oxygen, it undergoes efficient epoxidation to styrene epoxide. This is the first demonstration of alkene epoxidation on the surface of a clean metal, other than silver. However, styrene adsorbed on the 'oxidic' p(2 x 1)-O surface is catalytically inert. The NEXAFS data indicate that the reactant molecule is oriented approximately parallel to the surface plane on both the clean and oxidic p(2 x 1)-O surfaces, so that the very different reactivity is unlikely to be due to geometrical effects. The implications of these findings for the mechanism of heterogeneous alkene epoxidation are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.