Epoxidation of propylene by molecular oxygen at low temperature over AgCl-modified Ag-Cu bimetallic catalyst

Abstract

As molecular oxygen is the cheapest oxidant, the epoxidation of propylene by molecular oxygen is a topic of great interest and also the most challenge topic in the heterogeneous catalysis. However, the epoxidation of propylene by only molecular oxygen has yet to be optimised to a significant extent. Here we show, AgCl-modified Ag₂₀Cu/BaCO₃ bimetallic catalysts, prepared by in situ reduction co-deposition methods, were demonstrated to exhibit excellent catalytic activity for the epoxidation of propylene. First-principles density functional theory calculations were carried out to explore the inherent reaction mechanism and promotion effect of Cu and Cl addition. The addition of AgCl to Ag₂₀Cu/BaCO₃ bimetallic catalyst inhibited total oxidation of propylene, but enhanced both the rate of PO formation and PO selectivity. The highest PO selectivity of ∼100 % was achieved over 2400 ppm AgCl-Ag₂₀Cu-/BaCO₃ bimetallic catalyst at 80 °C.