Some aspects of the vapor phase Beckmann rearrangement for the production of ε-caprolactam over high silica MFI zeolites

Abstract

A high silica MFI zeolite catalyst has been developed for the vapor phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam. Methanol fed into the reactor with the oxime improves the yield of caprolactam. Methanol is not converted to dimethylether during the reaction. Moreover, when ammonia is fed to the catalyst with cyclohexanone oxime and methanol, the selectivity remains at a high level, without affecting the conversion. Hence, we conclude that the active sites of high silica MFI are extremely weak acid sites that cannot be detected by ammonia TPD measurement. A fluidized bed reaction system has been developed for the manufacturing process of caprolactam. High quality product is obtained with more than 95% yield.