Abstract: Bi-modified vanadium-phosphorous oxide (Bi-VPO) catalysts were prepared and used in liquid-phase oxidation of cyclohexane. The results showed that Bi modification could greatly enhance the catalytic performance of Bi-VPO for the oxidation of cyclohexane under mild conditions. The experiments without any solvent and with tetrahydrofuran as a solvent indicated the existence of interaction between acetonitrile and hydrogen peroxide. The free radical trap experiment proved that a free radical process is present in the catalytic system. The oxidation experiment of cyclohexanol explained that cyclohexanone is derived directly from cyclohexane oxidation instead of cyclohexanol oxidation.

Key words: bismuth, vanadium-phosphorous oxide, cyclohexane, liquid-phase oxidation, reaction mechanism