The highly selective aerobic oxidation of cyclohexane to cyclohexanone and cyclohexanol over V₂O₅@TiO₂ under simulated solar light irradiation

The highly selective aerobic oxidation of cyclohexane to cyclohexanone and cyclohexanol (KA-oil) under benign and green conditions is still a challenging topic. In this work, V₂O₅@TiO₂ catalysts were prepared by V species deposited on TiO₂ (P25) and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and UV-vis diffuse reflectance techniques. The selective aerobic oxidation of cyclohexane was carried out over V₂O₅@TiO₂ catalysts with oxygen as an oxidant under simulated light irradiation. The influences of solvents, metals and mass of V species deposited on TiO₂, pressure of oxygen, and reaction time on the reaction were investigated. It was found that the V species deposited on the TiO₂ surface was very efficient for the photocatalytic oxidation of cyclohexane under simulated solar light irradiation. More interestingly, the selectivity of the reaction in an acetonitrile/water mixed solvent was much higher than that in other solvents. Under the optimized conditions, the selectivity to KA-oil products could be nearly 100% at a cyclohexane conversion of 18.9%. The possible pathway for the catalytic reaction was proposed.