Effect of nickel on catalytic behaviour of bimetallic Cu-Ni catalyst supported on mesoporous alumina for the hydrogenolysis of glycerol to 1,2-propanediol

The catalytic conversion of glycerol to 1,2-propanediol by hydrogenolysis has potential use in the commercial biomass industry. However, the high hydrogen pressure required for the reaction is a major drawback. To overcome this limitation, in this study, we added nickel metal to a copper-based catalyst for both supplying hydrogen via aqueous-phase reforming (APR) of glycerol and improving selectivity for 1,2-propanediol in hydrogenolysis. The bimetallic Cu-Ni catalyst supported on mesoporous alumina (MA) was prepared by a sol-gel method. The prepared Cu-Ni catalyst contains ordered mesopores with high surface area and well-dispersed active sites, as confirmed by BET, TEM, XRD, and TPR. The 9Cu-1Ni/MA (molar ratio of copper to nickel: 9 : 1) catalyst showed the highest catalytic performance among the various xCu-yNi/MA catalysts in a low pressure of H-2. The XPS results showed that the surface ratio of Ni to (Cu + Ni) and Cu-0/(Cu-0 + Cu2+) is closely related to catalytic performance, selectivity and yield. The effect of nickel on the hydrogen production was experimentally proven by the time-on-stream tests over monometallic (Cu) and bimetallic (Cu-Ni) catalysts in the absence of hydrogen. The optimum value of the ratio of Ni to Cu is varied with the conditions in the presence of H-2. The reaction mechanism was proposed for the Cu-Ni bimetallic catalysts for hydrogenolysis with APR of glycerol.