Ester hydrogenolysis over promoted Cu/SiO2 catalysts

A series of Cu/SiO2 catalysts promoted with manganese, iron, cobalt, nickel, molybdenum, magnesium and yttrium was prepared by homogeneous deposition precipitation. For most catalysts a copper metal surface of about 15 m2 g−1 catalyst is measured. TPR reveals that copper–promoter contact is good for most samples. Despite similar Cu0 surface areas, ester hydrogenolysis activity varies considerably with the type of promoter, in the following order: Mo>Co≥Zn≥Mn>Fe≥Y>Ni≫Mg. As a function of metal–oxygen bond strength, a vulcano type catalyst activity plot is observed. With respect to alkanes formation, a correlation with normalised electronegativity is observed, inferring that the formation of alkanes proceeds on Lewis acid sites, which is in agreement with literature results. When both activity and selectivity are taken into account, manganese and zinc are the promoters of choice.