Catalytic performance of Pt/AlPO4 catalysts for selective hydrogenolysis of glycerol to 1,3-propanediol in the vapour phase

Abstract

Hydrogenolysis of glycerol to 1,3-propanediol was investigated in the vapour phase over a series of Pt/AlPO₄ catalysts with platinum loadings ranging from 0.5 to 3 wt%. The catalysts were prepared by a wet impregnation method and characterized by various techniques such as X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), BET surface area, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and CO-chemisorption methods. Ex situ pyridine adsorbed FTIR analysis and temperature programmed desorption (TPD) of NH₃ were employed to investigate the acidic properties of the catalysts. Further, the effect of reaction temperature, hydrogen flow rate, glycerol concentration and various contents of platinum (0.5 to 3 wt%) have been investigated to find the optimum reaction conditions. Superior performance with almost 100% conversion of glycerol and above 35% selectivity to 1,3-propanediol was obtained over 2 wt% Pt/AlPO₄ at 260 °C and atmospheric pressure. The influence of acidity of the catalyst and its correlation to the catalytic performance (selectivity and conversion) has been studied. The high strength of weak acidic sites and Brønsted acidity of the catalyst measured by NH₃-TPD and Pyr-FTIR were concluded to play a key role in selective formation of 1,3-propanediol. XRD, TEM and CO-chemisorption studies revealed that platinum was well dispersed on AlPO₄ which further contributed to higher catalytic activity for glycerol hydrogenolysis.