Dynamic redox cycle of Cu0 and Cu+ over Cu/SiO2 catalyst in ester hydrogenation

Abstract

Esters (methyl acetate, ethyl acetate, dimethyl oxalate) can oxidize Cu⁰ of the reduced Cu/SiO₂ catalyst to Cu⁺ and the obtained Cu⁺ can be reduced back to Cu⁰ by H₂ under reaction conditions. Cu⁰ and Cu⁺ are in a dynamic cycle during ester hydrogenation. The ratio of Cu⁺/Cu⁰ in the presence of esters under reaction conditions is probably different from that in the absence of esters under characterization conditions. The effect of the dynamic cycle on the Cu⁺/Cu⁰ ratio should be taken into consideration when establishing the relationship between the Cu⁺/Cu⁰ ratio and reaction performance.