Efficient Co3O4/SiO2 catalyst for the Baeyer-Villiger oxidation of cyclohexanone

Silica-supported tricobalt tetraoxide (Co3O4/SiO2) catalysts prepared by the impregnation approach with different cobalt loadingswere evaluated in the Baeyer-Villiger oxidation of cyclohexanone under Mukaiyama conditions. Among those catalysts with different cobalt contents, 0.5 wt% Co3O4/SiO2 afforded the best cyclohexanone conversion. Also, it provided comparable activity to regular cubic Co3O4, which was synthesized by a sophisticated hydrothermal method, under similarly mild conditions. Results of various physico-chemical characterizations, including XRD, HRTEM, TEM, H-2-TPR and O-2-TPD, revealed that highly dispersed Co3O4 catalysts showed higher reducibility than those lower dispersed catalysts and possessed more surface oxygen species which seemed reasonable to enhance catalytic activity. The application of Co3O4/SiO2 catalyst in oxidation of cyclohexanone is promising due to its relatively low-cost, high efficiency and excellent stability.