Silicalite-1 zeolite nanosheets with rich H-bonded silanols for boosting vapor-phase Beckmann rearrangement: One-pot synthesis and theoretical investigation

Abstract

Design and preparation of highly efficient zeolite catalysts for gas-phase Beckmann rearrangement of cyclohexanone oxime to caprolactam are attractive but still challenging. Herein, we show a one-pot synthesis of silicalite-1 zeolite nanosheets with rich H-bonded silanols. The key to this success is the use of urea in the synthetic system. Catalytic tests of cyclohexanone oxime gas-phase Beckmann rearrangement show that the silicalite-1 zeolite nanosheets with H-bonded silanols exhibit higher selectivity for caprolactam and longer reaction lifetime than those of the conventional silicalite-1 zeolite. Theoretical simulations reveal that the ammonium decomposed by urea is a critical additive for the formation of H-bond silanols. Obviously, one-pot synthesis of silicalite-1 zeolite nanosheets with rich H-bonded silanols plus excellent catalytic performance in the Beckmann rearrangement offer a new opportunity for development of highly efficient zeolites for catalytic applications in the future.