Vanadia loaded hierarchical ZSM-5 zeolite: a promising catalyst for epoxidation of cyclohexene under solvent free condition

Hierarchical ZSM-5 zeolite with composite micro and mesoporous was obtained by alkali treatment of parent ZSM-5 for 60 min. Vanadia was loaded on modified zeolite by wetness impregnation technique (VDZ). The prepared samples were characterized by various techniques including XRD, FTIR, TGA, UV-DRS, TEM, XPS and nitrogen adsorption–desorption. Vanadia loaded sample was found to exhibit excellent catalytic activity for the epoxidation of cyclohexene by tertiary butyl hydroperoxide. A controlled reaction was carried out to demonstrate the utility of hierarchical topology of the catalyst. A free radical mechanism was proposed for the reaction with rate constant of 6.91 × 10−2 L mol−1 min−1 and activation energy of 41.81 kJ mol−1. The reaction was carried out without the use of any solvent and the catalytic activity of VDZ was retained even after five runs.