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

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.

The catalytic efficiency of the sulfated V2O5/SnO2 systems in the gas-phase Beckmann rearrangement of cyclohexanone oxime is presented in this paper. The catalysts were characterized thoroughly using different techniques like EDX, BET-SA, XRD, FTIR, TGA, 51V NMR. NH3-TPD and hydrocracking of cumene were used for measuring the surface acidity of the prepared catalysts. The results of the investigation suggest that the acidity of the supported vanadia systems plays an imperative role in the activity and selectivity in the reaction.Figure optionsDownload as PowerPoint slide