Abstract
Abstract The activity and selectivity of vanadium phosphate (VPO) catalysts on the mesoporous KIT-6 support for green oxidation of cyclohexane to cyclohexanone and cyclohexanol were studied using H2O2. The catalysts were characterized using XPS, XRD, ICP-AES, TEM, SEM, EDX, BET, FT-IR and adsorption of pyridine. Small angle X-ray diffraction spectroscopy confirmed formation of well-ordered mesoporous KIT-6 material. The BET analysis showed a high surface area and well-ordered support formed. The XRD analysis demonstrated the loaded VPO existed almost wholly as VOHPO4 0.5H2O phases and after calcination converted mainly to the form of (VO)2P2O7 phase on KIT-6. XPS analysis revealed that a vanadium oxidation state of catalyst is approximately 4+. Within the studied range, the optimum condition to improve cyclohexane conversion and selectivity towards KA-oil (a mixture of cyclohexanone and cyclohexanol) over vanadium containing catalyst was performed in the presence of 27 wt% catalyst VP-loading at 65 °C with 1:4 (cyclohexane: H2O2) molar ratio, in acetonitrile. Under these reaction conditions 19.3% conversion and 69.9% selectivity for KA-oil were observed after 4 h of reaction time. Finally, the recyclability of the catalyst was studied through five consecutive catalytic runs.
Published Version
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