Mesoporous molecular sieve Al-MCM-41 as a novel catalyst for vapor-phase Beckmann rearrangement of cyclohexanone oxime

Vapor-phase Beckmann rearrangement of cyclohexanone oxime to epsilon -capro lactam has been studied at 1 atm and 300-400 degreesC using mesoporous mole cular sieve Al-MCM-41. Benzene and ethanol are utilized as solvents for cyc lohexanone oxime. Increasing the reaction temperature enhances the catalyst activity and stability whereas epsilon -caprolactam selectivity varies onl y slightly. Ethanol exhibits much better catalytic results than benzene. Ex cellent catalyst performance is attained at 1 atm, 400 degreesC and W/F-C 1 49.2 g h/mol by using ethanol in the feed; the cyclohexanone oxime conversi on and the epsilon -caprolactam selectivity remain higher than 99 and 90%, respectively, during at least 1200 h process time. The highly efficient cat alysis on Al-MCM-41 is attributed to its large surface area, uniform mesopo res as well as the weak and medium acidity.