Synthesis of hierarchical porous silicalite-1 and its catalytic performance in Beckmann rearrangement

• A simple method has been developed to produce hierarchically porous silicalite-1.
• The sample showed hierarchical porosity and large pore volume.
• The sample showed higher catalytic activity than conventional silicalite-1 in Beckmann rearrangement.

Hierarchical porous silicalite-1 with micropores and mesopores was successfully synthesized via dry gel conversion route using tetrapropylammonium hydroxide (TPAOH) and polyvinyl alcohol (PVA) as microporous and mesoporous templates, respectively. The obtained hierarchical porous silicalite-1 was characterized by X-ray diffraction (XRD), nitrogen adsorption and desorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The characteristics of the samples are comparable with conventional silicalite-1. The influence of the PVA on the hierarchical porous properties of the samples was investigated. The hierarchical porous silicalite-1 showed higher activity and selectivity than conventional silicalite-1 in vapor phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam under reaction condition.

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