Aqueous phase hydrogenolysis of glycerol to bio-propylene glycol over Pt–Sn catalysts

PtSn supported on SiO2 obtained via surface organometallic chemistry techniques catalyzes hydrogenolysis of glycerol to obtain bio-propylene glycol (PG). Bimetallic catalysts with Sn contents between 0.1% and 1% wt were carefully prepared by selective hydrogenolysis of Sn(n-C4H9)4 on Pt. TEM, TPR, H2 and CO chemisorptions, and XPS studies have shown that tin selective deposition on the metallic phase is obtained. At 200 °C under N2 or H2 pressure, the presence of tin increases drastically: both the selectivity and the activity of the glycerol conversion into PG. During 2 h batch runs; it could be observed that PtSn catalysts with Sn/Pt ratio = 0.2 showed the best performance (PG selectivity = 59% and 83% under N2 and H2 pressure respectively). The increase in activity and selectivity could be explained by the presence of Sn+n species “acid Lewis sites” which would facilitate the C–OH adsorption and its subsequent C–O cleavage favoring the propylene glycol production.