Chemistry of olefins at metal oxide surfaces: a tool for surface science investigation of oxide catalysts

Abstract

The results of IR investigations of the adsorption of simple olefins (ethylene, propylene and isobutene) on a number of metal oxide catalysts are summarized. The spectroscopic features of molecularly adsorbed species interacting with the surface via H-bonding, via σ-type electron donation over d o cations and via σ-type donation with π-type back donation on d-electron-containing cations are briefly discussed. Evidence for surface reactivities including: 1. i) oxidative breaking of the C=C bond; 2. ii) hydroxylation of the C = C bond giving alkoxides; 3. iii) proton induced cationic polymerization; 4. iv) proton abstraction at the allylic position giving anionic allyl species; 5. v) hydrogen abstraction at the allylic position giving radical-like allyl species; 6. vi) adsorption with hydrogen transposition giving metal alkylidene species; is also discussed on particular surfaces.