Bimetallic Effects of Silver-Modified Nickel Catalysts and their Synergy in Glycerol Hydrogenolysis

Graphical Save it for a Raney day : A series of Ag-modified Ni catalysts is prepared, and the role of bimetallic effects on the selective cleavage of C−O and C−C bonds is investigated in glycerol hydrogenolysis, a model reaction for the utilization of biomass-derived polyols. Compared to Raney Ni, the optimal Raney Ni 6 Ag catalyst is more active in glycerol conversion and efficient for C−O bond cleavage to afford a higher selectivity toward C 3 products. A series of Ag-modified Ni catalysts was prepared, and the role of bimetallic effects on the selective cleavage of C−O and C−C bonds was investigated in glycerol hydrogenolysis, a model reaction for the utilization of biomass-derived polyols. Compared to Raney Ni, the optimal Raney Ni 6 Ag catalyst was more active in glycerol conversion and efficient for C−O bond cleavage to afford a higher selectivity toward C 3 products (1,2-propanediol and lactic acid; 88 %) at the same ∼70 % conversion of glycerol, especially 1,2-propanediol (73 %). On Ni catalysts, the hydrogenation of adsorbed species was the most likely rate-limiting step in glycerol hydrogenolysis under alkaline conditions. The Ag additive enhanced the hydrogenation ability of Ni catalysts, which should be related to the higher strength of the adsorption of hydrogen and the lower strength of the adsorption of substrates on Ni sites because of the formation of Ni-Ag alloys. A mechanistic interpretation was presented for the excellent catalytic behavior.