A comparative study of molybdenum promoted vanadium phosphate catalysts towards epoxidation of cyclohexene

Abstract

This article describes our efforts in developing molybdenum promoted vanadium phosphate (Mo-VPO) catalyst by two distinct methods and its application in liquid phase oxidation reactions. The materials were characterized by various spectral techniques and their catalytic potential has been investigated for the oxidation of cyclohexene. The influences of various reaction parameters have also been studied. Under optimum reaction conditions excellent to higher yield of epoxide (91%) was obtained by Mo-VPO* prepared by impregnation method. The promoting effect of Mo on VPO solids was found to be a function of the way the ion was added during the preparation of the VOHPO4 center dot 0.5H(2)O phase. XPS analysis of the catalysts showed the presence of couple V4+/V5+ on the surface of Mo-VPO which facilitates the reaction. The catalyst showed its recapability more than four times without any appreciable change in conversion and selectivity. The synergetic effect between Mo and V, to the contrary, made the active phase, VPO, more stable. (C) 2013 Elsevier B.V. All rights reserved.