Effective ternary copper-cerium-cobalt catalysts synthesized via a modified pechini method for selective oxidation of ethylbenzene

Abstract

A series of ternary Cu-Ce-Co catalysts were synthesized via a modified pechini method, in which the metal complexes annealed at 650 °C under nitrogen atmosphere and then heated at air. Different surfactants such as citric acid, CTAB, P123 and ILs (1-Butyl-3-methylimidazolium chloride) were used to obtain metal catalysts with high surface areas and uniform sizes. The techniques such as N2 adsorption-desorption, XRD, TEM, Raman and XPS were employed to characterize the catalysts. The results demonstrated that the pretreatment in inert gas atmospheres and the incorporation of appropriate surfactant could effectively restrain the aggregation and growth of active metal species, which resulted in the formation of highly dispersed active sites. The selective oxidation of ethylbenzene using oxygen as oxidant under solvent-free conditions was adopted to evaluate the catalytic activity. Approximately 44.4% ethylbenzene conversion with 83.0% selectively to acetophenone was obtained over the optimized catalyst. The superior catalytic performance of the catalysts was attributed to the synergistic effect of the factors such as the high surface area (160 m2/g), well-dispersed active metal sites and high content of active sites.