Roles of WOx on Pt/γ-Al2O3 catalysts on the prevention of Pt metal sintering during hydrogenolysis of glycerol to 1,3-propanediol

Abstract

Hydrogenolysis of glycerol to produce 1,3-propanediol is the most effective reaction which conversing excess glycerol from biodiesel production to high-value-add product; especially, 1,3-propanediol. A solid catalyst which generally used as selective to 1,3-propanediol production is Pt-based catalyst with γ-Al2O3 supporter which was prepared by wet impregnation method in this study. Although hydrogenolysis of glycerol reaction has been carried out under mild conditions: 140 °C and 5 bar of initial H2 pressure, the deactivation of non-reduced Pt/γ-Al2O3 catalyst is observed. To investigate the deactivation of the catalyst, the used Pt/γ-Al2O3 and Pt/WOx/γ-Al2O3 catalysts were characterized by N2-physisorption, ICP-OES, SEM-EDX, XRD, Py-IR, TPO and FTIR. In this study, deactivations are leaching, sintering and coke formation on both Pt/γ-Al2O3 and Pt/WOx/γ-Al2O3 catalyst during the hydrogenolysis of glycerol in liquid phase. WOx can hinder the sintering of Pt metal and retard the coke formation on the catalyst surface. Furthermore, the existence of WOx on Pt/WOx/γ-Al2O3 catalysts can also improve catalytic activity for glycerol conversion. Moreover, Pt/WOx/γ-Al2O3 catalysts can significantly increase the selectivity of 1,3-propanediol beyond 1,2-propanediol. Nevertheless, the stability of Pt/WOx/γ-Al2O3 catalyst is better than that of Pt/γ-Al2O3 catalyst indicated by lower conversion drop of the used catalyst after the first hydrogenolysis of glycerol. Consequently, the addition of WOx on Pt/γ-Al2O3 catalyst makes appropriated Pt-based catalyst performing in hydrogenolysis of glycerol in terms of higher activity, the selectivity of wanted 1,3-propanediol and stability of the catalyst.