Reactions of peroxide radicals with the surface of heterogeneous catalysts in homolytic and heterolytic processes

Abstract

An interrelation between homolytic and heterolytic stages is found for olefin epoxidation by hydroperoxides and cumene hydroperoxide decomposition in the presence of a heterogeneous catalyst (molybdenum selenide). Peroxide radicals that are formed in homolytic decomposition of the hydroperoxide interact with the catalyst surface. As a result, molybdenum atoms are oxidized to the highest valence state, and new reaction sites are created, on which heterolytic reactions occur. It is shown that olefin, as an electron donor, decreases the catalyst activity in the heterolytic reactions. The limited value for the olefin epoxidation rate, which is independent of the amount of the catalyst used, is explained by the disappearance of active sites on the catalyst surface due to their interaction with the neighboring sites containing adsorbed olefin molecules.