Glycerol hydrogenolysis to n-propanol over Zr-Al composite oxide-supported Pt catalysts

Abstract

Zr-Al mixed oxide supported Pt catalysts with different Zr/Al mole ratios (2.5%Pt/ZrxAl1–xOy) were synthesized by an impregnation method and used for the selective hydrogenolysis of glycerol to n-propanol in an autoclave reactor. The catalysts were fully characterized by X-ray powder diffraction, Brunauer-Emmett-Teller surface area analysis, CO chemisorption, H2 temperature- programmed reduction, pyridine-infrared spectroscopy, and NH3-temperature-programmed desorption. The results revealed that the Zr/Al ratio on the support significantly affected the size of the platinum particles and the properties of the acid sites on the catalysts. The catalytic performance was well correlated with the acidic properties of the catalyst; specifically, more acid sites contributed to the conversion and strong acid sites with a specific intensity contributed to the deep dehydration of glycerol to form n-propanol. Among the tested catalysts, 2.5 wt% Pt/Zr0.7Al0.3Oy exhibited excellent selectivity for n-propanol with 81.2% glycerol conversion at 240 °C and 6.0 MPa H2 pressure when 10% aqueous glycerol solution was used as the substrate. In addition, the effect of various reaction parameters, such as H2 content, reaction temperature, reaction time, and number of experimental cycles were studied to determine the optimized reaction conditions and to evaluate the stability of the catalyst.