Acrylate and propoxy-groups: Contributors to deactivation of Au/TiO2 in the epoxidation of propene

Reaction pathways of propene in the selective propene epoxidation over Au/TiO2 are discussed on the basis of in-situ IR spectra. A non-selective route for conversion of propene via acrylate to carboxylates and carbonates is demonstrated, likely contributing to catalyst deactivation. Propoxy-groups are predominantly formed by reaction of the catalyst surface with the reaction product propene oxide (PO), and are highly stable under reaction conditions. These propoxy-groups are considered as deactivating species, and not as intermediates for the production of PO, or carboxylates and carbonates.