Dehydroxylation of glycerol on nickel-containing catalysts: A method of utilization of glycerol in biodiesel production

The catalytic dehydroxylation of glycerol in a flow mode was studied. This is one of the methods for utilization of excess glycerol accumulated during the production of biodiesel fuel. Raney nickel and Ni-Cr2O3 were used as catalysts. The possibility of glycerol dehydroxylation on Raney nickel and Ni-Cr2O3 catalysts in flow units was studied for the first time. The Raney catalyst showed higher activity in glycerol dehydroxylation compared with Ni-Cr2O3. At 220°C and 2 MPa, the conversion of glycerol and the yield of 1,2-propanediol was 88 and 35% on Raney nickel versus 16 and 6.5% on Ni-Cr2O3, respectively. The reaction under the given conditions, however, formed large amounts of by-products: ethylene glycol, simple alcohols, and methane. At pressures of H2 of over 2 MPa, the yield of the acetol by-product decreased considerably, ultimately increasing the efficiency of the process. The Raney catalyst can be used for the dehydroxylation of glycerol in flow units under relatively mild conditions (up to 240°C and 2 MPa).