Hydrogenolysis of glycerol to obtain 1,2-propanediol on Ce-promoted Ni/SBA-15 catalysts

Abstract

[EN]Metallic Ni (10 wt.%) supported on SBA-15 silica and promoted with cerium loading ranged between 2.5 and 10 wt.%, reduced at 723 K during 1 h, were used as catalysts in the hydrogenolysis of a glycerol aqueous solution (80 wt.%) at 473 K and 2.4 MPa of H2 pressure. Whereas pure Ni catalyst mainly produces volatile products by Csingle bondC hydrogenolysis reaction, the promoted cerium catalysts lead to the formation of 1,2-propanediol (1,2-PDO) as majority product. After 8 h of reaction the catalyst with 10 wt.% of Ni and 7.5 wt.% of Ce gives the maximum glycerol conversion and selectivity to 1,2-PDO, with yield of this substance of 24.2%/g of catalyst. The presence of cerium species is essential to produce 1,2-PDO. The effect of cerium oxide is to act as strong acid sites (TPD-NH3), improve the metallic Ni dispersion (XRD, H2 chemisorption and XPS) and to make more difficult their reduction (TPR). The stronger acidity suggests that the formation of acetol takes place easier in these catalysts and subsequently this intermediate is reduced by activated hydrogen from the nearby Ni metallic sites.