Hydrogenolysis of glycerol to propanediols over supported Ag-Cu catalysts

Hydrogenolysis of glycerol to 1,2-propanediol and 1,3-propanediol has significant scientific importance and commercial interest due to the huge surplus of glycerol and the various application of propanediols. A series of supported Ag-Cu catalysts synthesized by impregnation method were studied for hydrogenolysis of glycerol to propanediols. The catalysts were characterized by H-2-TPR, NH3-TPD, XRD, BET, N2O chemisorption, TG, ICP and SEM. It was observed that the loading of 5% Ag-Cu-based catalysts facilitated the reduction, surface acidity and dispersion of the Cu particles, which improved the conversion of glycerol and promoted the generation of propanediols. It was also found that when loading Ag and Cu simultaneously on Al2O3, the catalyst had a better performance for the reaction because of the higher acidity, dispersion and surface area of the Cu species on the catalyst surface. In addition, effects of metal concentrations, metal impregnation sequence, reaction temperature, reaction pressure, reaction time, solvent and pH value of the solution on glycerol hydrogenolysis together with the recyclability of catalyst were investigated in detail. The optimal 5Ag-15Cu/Al2O3 achieved 66.4% glycerol conversion with 68.2% 1,2-propanediol and 3.1% 1,3-propanediol selectivity at 200 A degrees C under 3.5 MPa in ethanol for 8 h.