Hydrogenolysis of glycerol aqueous solution to glycols over Ni–Co bimetallic catalyst: effect of ceria promoting

Abstract

A series of Ni–Co bimetallic catalysts supported on γ-Al2O3 with different Ni/Co mass ratio were prepared by incipient wetness impregnation method for glycerol hydrogenolysis. The catalyst with a Ni/Co mass ratio of 1:3 (denoted as Ni1Co3) exhibited the highest conversion. The performance was compared with that of catalysts promoted by Ce. Moreover, the addition of Ce showed a remarkable promoting effect on the catalytic performance when the cerium content was 2.5 wt%. The physicochemical properties of the supported Ni–Co catalysts were characterized by N2 physisorption, XRD, H2-TPR, NH3-TPD, XPS and TEM. H2-TPR profiles revealed that the coexistence of Ni and Co components on support changed the respective reduction behavior of Ni or Co alone, showing the synergistic effect between Ni and Co species. Compared with the TPR profiles of Ni1Co3, it was clearly observed that the reduction peak of nickel oxide and/or cobalt oxide shifted down to the lower temperature zone gradually with the addition of Ce. It was most probable that the addition of Ce favored the formation of the strong interaction between metal species and ceria. The TEM images showed that the addition of Ce component could improve the dispersion of Ni–Co species on support and inhibited the agglomeration of metal particles during the reaction process, which might be responsible for the enhanced stability.