Enhanced catalytic performance for selective oxidation of propene with O 2 over bimetallic Au–Cu/SiO 2 catalysts

Au–Cu bimetallic nanoparticles with uniform size, shape, and compositions were synthesized by wet chemistry method, and then the Au–Cu/SiO2 catalyst supported on SiO2 was prepared. Meanwhile, their catalytic activity for the selective oxidation of propene to acrolein using O2 as an oxidant was evaluated. The bimetallic catalyst shows a significantly enhanced catalytic performance comparing with Au and Cu monometallic catalysts. Characterization of the materials and kinetic study was conducted to explore the cooperating mechanism of Au and Cu for improving the catalytic activity of the bimetallic catalyst. Cu component can segregate to the alloy surface and the Au–Cu alloy transferred to Au–CuO core/shell structure after annealing during the preparation process. Based on the Mars–van Krevelen mechanism for the selective oxidation of propene over the prepared catalysts, the coexistence of CuO can promote the adsorption and activation of O2. Meanwhile, the electrons transfer from Au to Cu in the catalyst can facilitate the adsorptions of both oxygen on CuO sites and propene on Au sites. The combined effects of the above two aspects result in the high catalytic activity of the Au–Cu/SiO2 catalyst for selective oxidation of propene to acrolein, compared to the Au/SiO2 and CuO/SiO2 catalysts.