Mechanism of photo-oxidation of propene over vanadium oxide supported on silica

Abstract

The nature of the active oxygen species and intermediates in the photo-oxidation of propene over vanadium oxide supported on silica has been investigated and a possible mechanism is proposed. The phosphorescence spectra confirm that the active species is the photoexcited VO bond in the catalyst. Aldehydes produced by the oxidation of propene with ¹⁸O₂ contained little ¹⁸O, showing that excited lattice oxygen is the species directly involved in attacking propene. A kinetic study of the photoadsorption of oxygen on a sample of the catalyst having preadsorbed propene showed that the first intermediate comprises one molecule of propene and one molecule of oxygen. The formation of a π-allyl intermediate is suggested from the results of the photo-oxidation of deuterated propene.