Facile conversion of glycerol to 1,3-dihydroxyacetone by using mesoporous CuO-SnO2 composite oxide supported Au catalysts

Selective catalytic oxidation of polyols, e.g., the selective catalytic oxidation of the secondary -OH bond in glycerol, remains a considerable challenge. In this study, a series of mesoporous CuO-SnO2 composite oxides were prepared by a hard-template method and used to support Au catalysts for the selective oxidation of glycerol to 1,3-dihydroxyacetone (DHA) under base-free conditions. Catalysts with different Cu:Sn molar ratios gave different catalytic performances. A high conversion of glycerol (100%) and selectivity for DHA (94.7%) were obtained in 2 h at 80 degrees C and P-O2 = 1 MPa over the Au/CuO-SnO2-3:1 catalyst. Further investigation indicated that the high catalytic activity of Au/CuO-SnO2-3:1 is related to the small size and high dispersion of Au nanoparticles (NPs), the interactions between the Au NPs and the support, the synergistic effect between CuO and SnO2, and the amount of surface lattice oxygen species. Various reaction parameters, namely the glycerol:Au molar ratio, the reaction temperature, the initial O-2 pressure, the reaction time, and the support calcination temperature were studied. Although the conversion rate by the catalyst decreased after four cycles, the selectivity remained above 86%. Density functional theory calculations showed that the synergy between CuO and SnO2 improves the catalytic activity in glycerol oxidation to DHA. The results show that mesoporous composite oxide supports have a wide range of potential applications in the selective oxidation of glycerol to other high-value-added products.