Preparation of Silicalite-1 Nanosheets and its Application in Vapor-Phase Beckmann Rearrangement of Cyclohexanone Oxime

Silicalite-1 nanosheets catalyst with a hierarchical architecture was hydrothermally synthesized using [C18H37-N+(CH3)2-C6H12-N+(CH3)2-C6H13](Br)−2 as template. It has been studied systematically by investigating the influence of different synthesis parameters and crystallization kinetics under tumbling conditions. Highly crystalline silicalite-1 nanosheets with large external surface was obtained by regulating the crystallization time and the amount of water, template and the alkalinity. It was examined as catalyst for vapor-phase Beckmann rearrangement of cyclohexanone oxime to caprolactam and exhibited an excellent catalytic performance and long catalytic lifetime. This can be attributed to nest silanol groups located on the large external surface of the nanosheets. Furthermore, the high mesoporosity of nanosheets shorten the diffusion path length and reduce coking deposition, which remarkably improve catalyst stability.