Abstract: Four vanadium phosphorus oxides (VPO) catalysts modified by Fe, Co, Ni and Bi respectively were prepared and characterized by XRD and SEM. The average oxidation values of vanadium in these catalysts were determined by oxidation-reduction titration. The synthesis of cyclohexanone from cyclohexane using hydrogen peroxide as oxidant over various modified VPO catalysts was carried out in the liquid phase to compare the catalytic performance of these catalysts. Test results showed that the catalytic activities for cyclohexane to cyclohexanone of these catalysts from high to low were in the order of Bi-VPO> Fe-VPO > Ni-VPO> Co-VPO > VPO. Under the conditions of a cyclohexane amount of 0.6 mL, an acetone amount of 10 mL, a Bi-VPO catalyst dosage of 0.015 g, a hydrogen peroxide amount of 3 mL, a reaction temperature of 65℃ and a reaction time of 8 h, the conversion of cyclohexane reached 81.4%, the yields of cyclohexanone and cyclohexanol were 58.2% and 23.2%, respectively.

Key words: cyclohexane, liquid-phase oxidation, hydrogen peroxide, vanadium phosphorus oxides