Effect of promoters on the selective hydrogenolysis of glycerol over Pt/W-containing catalysts

Abstract

Diverse promoters, including noble metals (such as Ru, Ir and Rh) and transition metal oxides (such as Re, La, Fe, Zr, Sn and Ce oxides) were introduced into Pt/WOx and Pt/WOx/Al2O3 catalysts to investigate the ability of these promoters to modify activity and selectivity during glycerol hydrogenolysis to 1,3-propanediol. Among these, La exhibited the greatest promotional effect; the introduction of 0.1% La to the Pt/WOx improved activity, selectivity and stability, although the significant increase in selectivity came at the cost of a slight activity loss in the case of the Pt/WOx/Al2O3 catalyst. Transmission electron microscopy, high angle annular dark field scanning tunneling electron microscopy and NH3-temperature programmed desorption all demonstrated that the introduction of La generates a greater quantity of acidic sites on the catalyst surface, and that the majority of the La species are associated with Pt particles. Most of the other additives resulted in only minimal improvements or even detrimental effects with regard to both activity and selectivity, although some appear to improve the stability of the catalyst.