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  • 1 School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
  • | 2 College of Chemistry and Chemical Engineering, Bohai University, Jinzhou, 121000 People’s Republic of China
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A series of phosphorus modified Si-MCM-41 catalysts prepared via the impregnation method were used for the vapor-phase Beckmann rearrangement of cyclohexanone oxime to caprolactam. The catalysts were characterized by XRD, N2 adsorption, FT-IR, and NH3-TPD. The results indicated that weak acid sites increased with P content, leading to enhanced catalytic activity. The catalyst with Si/P mol ratio of 25 showed best performance at 633 K. The conversion of cyclohexanone oxime and the selectivity for caprolactam were 92.7 and 64.2%, respectively. The P–OH groups are main active sites for the Beckmann rearrangement. Grafting acid hydroxyl groups to cover the Si–OH groups may be a good way to improve the selectivity for this reaction.