Effect of ZnO incorporation on Cu–Ni/Al2O3 catalyst for glycerol hydrogenolysis in the absence of added hydrogen

Abstract

A series of Cu–Ni bimetallic catalysts were developed and used for glycerol hydrogenolysis to produce 1,2-propanediol in the absence of added hydrogen along with the isopropanol as hydrogen donor. The monometallic Cu catalyst can catalyze the dehydrogenation of isopropanol effectively, but the Cu species would be oxidized to Cu+ which led to the catalyst deactivation. Ni incorporation can change the reduction behavior of Cu catalyst and the formation of Cu–Ni alloy might promote the hydrogenation of acetol. Furthermore, the effect of ZnO incorporation on the catalytic performance of Cu–Ni/Al2O3 bimetallic catalyst for glycerol hydrogenolysis in the absence of added hydrogen was investigated. The addition of ZnO enhanced the acidity of catalyst surface, resulting in higher C–O bond cleavage activity. Comparing the H2-TPR profiles of Cu–Ni/Al2O3 with Cu–Ni/ZnO–Al2O3, it could be clearly observed that the reduction temperature was decreased remarkably by the addition of ZnO. XRD and SEM images revealed that the addition of ZnO inhibited the catalyst sintering and favored the formation of the strong interaction between Cu–Ni species and Al2O3 by the formation of the ZnAl2O4 phase.