Infrared studies of intermediates in the oxidation of propene on ZnO using 18O2

Abstract

The oxidation of olefins adsorbed on zinc oxide has been investigated by i.r. spectroscopy using ¹⁸O₂. ¹⁸O-substitution has been carried out with gaseous oxygen and/or surface lattice oxygen. The formation of a precursor before the oxidation of the π-allyl species to carboxylate has been confirmed. These results provide evidence that two types of carboxylate, containing C¹⁸O₂ and C¹⁶O¹⁸O, are formed and that one lattice oxygen atom and one oxygen atom originating from an adsorbed oxygen molecule are incorporated into the π-allyl species to form the precursor (C₃H₅O₂), presumably possessing some unsaturation and C—O bond character.