Synthesis, characterization of VPO catalyst dispersed on mesoporous silica surface and catalytic activity for cyclohexane oxidation reaction

Abstract

A precipitation-deposition method in an organic medium was used to prepare vanadium phosphorus oxide (VPO) catalysts supported on SBA-15 and TUD-1. Oxidation of cyclohexane has been examined over mesoporous silica supported VPO catalyst. The supported VPO catalyst has been characterized by XRD, N2 physisorption, SEM, HRTEM, H2-TPR and NH3-TPD techniques. The characteristic X-ray diffraction patterns of bulk VPO catalyst and VPO catalysts supported on mesoporous SBA-15 and TUD-1 showed that each of them are having well-crystallized vanadyl pyrophosphate [(VO)2P2O7] phase. The vanadium redox centers were easily accessible for supported VPO catalyst. The TUD-1 supported VPO catalyst had higher acidity as found in NH3-TPD studies. The conversion of cyclohexane increased in the case of VPO dispersed on TUD-1 mesoporous material. From SEM and HRTEM results it is found that the nature of the support and VPO loading had a profound influence on the crystallinity, morphology and chemical property of the dispersed VPO phase. The changes in all the property had a prominent role on its catalytic activity for the oxidation of the cyclohexane.