Catalytic properties of V2O5/SnO2 towards vapour-phase Beckmann rearrangement of cyclohexanone oxime Original Research Article

V2O5/SnO2 solid acid catalysts have been employed for the vapour-phase Beckmann rearrangement of cyclohexanone oxime to ɛ-caprolactam. Catalysts with different vanadia loading (3–15 wt%) were prepared by impregnation method and characterized by XRD, BET surface area, FTIR and 51V NMR techniques. The surface acidic properties were determined by temperature programmed desorption and cumene cracking reaction. Under optimized reaction conditions, catalyst with 9 wt% V2O5 gives the maximum amount of desired product (yield 78.8%). However, the catalysts are susceptible for deactivation due to the basic nature of the reaction products (50% deactivation in 5 h). A good correlation was obtained among the rearrangement activities of V2O5/SnO2 catalysts, their weak plus medium acidities (usually of the Brönsted type) and structural properties.