Effect of Metals on the Hydrogenolysis of Glycerol to Higher Value Sustainable and Green Chemicals Using a Supported HSiW Catalyst

Pt, Pd, Ni, and Cu supported on HSiW/Al2O3 catalysts were studied for the hydrogenolysis of glycerol. It was found that Pt is the best promoter for the production of 1,3-propanediol (1,3-PD) and 1-propanol (1-PO). Ni, a much cheaper metal, has fairly comparable reactivity to Pt, while Cu does not show any activity for the production of 1,3-PD. The catalysts were characterized by XRD and NH3-TPD. The strength of the acid sites affects the distribution of products. A reaction mechanism for a NiHSiW/Al2O3 catalyst involving rate-determining parallel dehydration of primary alcohol to produce acetal and of secondary alcohol to produce 3-hydroxypropylaldehdye (3-HPA) was proposed. Hydrogenolysis of 1,3-PD is 15 times slower than that of 1,2-PD. Most of the 1-PO is derived from 1,2-PD. An optimal balance of acid sites of appropriate acid strength and hydrogenation sites will lead to a highly selective catalyst for the production of higher value sustainable chemicals from glycerol.