Vapor phase selective hydrogenation of acetone to methyl isobutyl ketone (MIBK) over Ni/CeO2catalysts

Abstract

Ceria supported nickel oxide catalysts with varying nickel loadings from 1.0 to 20.0 wt% were prepared by the impregnation method. The catalysts were characterized by X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (UV-DRS), temperature programmed reduction (TPR), temperature programmed desorption (TPD) of CO₂, and surface area measurements. The dispersion of nickel and metal area were determined by the hydrogen chemisorption method. The X-ray diffraction patterns suggest the presence of crystalline NiO phase beyond 2.5 wt% of Ni on ceria. The UV-visible diffuse reflectance spectra reveal the presence of two types of nickel species on the CeO₂ support. TPR patterns reveal the presence of highly dispersed surface free nickel oxide species at lower temperatures and bulk NiO at higher temperatures. The basicity of the catalysts measured by the CO₂ TPD method was found to increase with an increase in nickel loading up to 2.5 wt% and decrease with further increase in nickel loading. The vapor phase condensation and selective hydrogenation of acetone to methyl isobutyl ketone (MIBK) were carried out on Ni/CeO₂ catalysts and the catalytic properties are correlated with the results of CO₂ TPD measurements and also with the dispersion of the nickel species supported on ceria.