Hydrogenation of phenol to cyclohexanone in aqueous phase on WO3 modified Ni/ZrO2 catalyst

Abstract

Ni/ZrO2 (Ni/Zr) and Ni/WO3-ZrO2 (Ni/xWZr, x denotes WO3/ZrO2 mass ratios) were prepared by the impregnation-direct reduction method and tested for the aqueous phase hydrogenation of phenol to cyclohexanone in an autoclave reactor. It has been found that the Ni-W alloy forms in Ni/xWZr, and a charge transfer occurs from Ni to W. The presence of W species promotes the Ni dispersion and increases the amounts of acid sites and spilt-over hydrogen species. This leads to higher hydrogenation and direct deoxygenation activity of Ni/xWZr than that of Ni/Zr. In addition, the W6+ and W4+ species, acted as Lewis acidic sites, may stabilize cyclohexanone and the hydrogenation of cyclohexanone to cyclohexanol is inhibited. Under suitable condition, the phenol conversion and the cyclohexanone selectivity reach 93.1% and 90.6% on Ni/0.8WZr, respectively.