Catalytic Hydrogenolysis Of Glycerol To 1,2-Propanediol

With the drastic dissipation of fossil energies, the searching for their substitution by bio-energy has been widely investigated. At present, biodiesel is an estabilished fast growing industry, accompanied by the massive generation of glycerol as the byproduct. Thus the high value-added utilization of glycerol deserves much research, among which, the hydrogenolysis of glycerol to 1,2-propanediol is of a considerable scale and high economic value.A series of ZrO2 supported copper catalysts were prepared by impregnation of incipient wetness method and tested in gas-phase hydrogenolysis of glycerol to 1, 2-propanediol. The pore structure, morphology, crystalline phase and reducibility of the catalysts were characterized by BET, TEM, XRD and H-TPR, respectively. The effect of support was screened in the preliminary tests, where SiO2 was found to be the best in activity and selectivity, but failed in stability; ZrO2 was the second best in activity, but inferior in selectivity. For purpose of modification, the elements of rare earths like La, Ce and Y were added in ZrO2 by co-precipitation method. The performance of catalysts was obviously improved after doping of La, Ce and Y in ZrO2 support, among which, yttria stabilized ZrO2(YSZ) was the best. Later, Ce was introduced as a promoter by successive impregnation of Cu and Ce precursors. The best catalyst was found to be 18 wt %Cu-4wt %CeO2/YSZ, with the average yield of 1, 2-propanediol over 93 %. Instrumental characterization revealed that this catalyst contained an open pore structure and BET surface area 107 m2/g, while its CuO crystal was also the smallest in size and easiest to reduce.A type of composite carriers, prepared by mixing carrier A and carrier B at different ratios, were developed as the supports for Cu-based catalysts and investigated on catalytic hydrogenolysis of glycerol for the first time. The conversion and selectivity of 1,2-propanediol remains 100% and above 94% respectively on Cu/AB-3 catalyst during time-on–stream test for over 2700 h, foreseeing a prospect of industrial application.