Identification of the Au/ZnO interface as the specific active site for the selective oxidation of the secondary alcohol group in glycerol

Abstract

In this work, a catalyst containing an Au/ZnO interface was synthesized using controlled thermal treatment to generate a strong metal–support interaction between Au and a thin amorphous ZnO layer, and was used for the aqueous oxidation of glycerol under base-free conditions. We provide evidence that the Au/ZnO interface is the specific active site for selective catalytic oxidation of the secondary alcohol group in glycerol, without affecting the primary alcohol groups, thus affording dihydroxyacetone with high selectivity. Characterization of the active catalyst suggests that ZnO species migrate to the surface of Au particles during thermal pretreatment in air. An Au–O–Zn interface is then formed, along with an abundance of oxygen vacancies. The resulting interfacial sites can specifically adsorb and activate the secondary alcohol group. The study provides more general insight into the role of Au-containing interfaces as the specific active sites in selective oxidation reactions.