Abstract: S-1 zeolites were synthesized by hydrothermal method, Fe was introduced to adjust the proportion of different silicon hydroxyl groups in the S-1 zeolites, and S-1 catalysts were obtained after post-treatment of the S-1 zeolites with N-containing buffer solution. The S-1 zeolites were characterized by XRD, N2 adsorption-desorption isotherm, FT-IR, ICP-AES, and SEM. The influences of Fe content and post-treatment of N-containing buffer solution on the physicochemical properties of the S-1 zeolites and their catalytic performances for the vapor phase Beckmann rearrangement of cyclohexanone oxime to produce ε-caprolactam were investigated. The results showed the optimum Fe content of S-1 zeolites was 254 μg/g, relative total amount of siloxane hydroxyl and the ratio of nested siloxane hydroxyl groups increased obviously after the post-treatment of N-containing buffer solution, and the conversion of cyclohexanone oxime to gas phase Beckmann rearrangement and the selectivity of cyclohexanone oxime to epsilon-caprolactam were to 99.9% and 95.0%, respectively.

Key words: cyclohexanone oxime, vapor phase Beckmann rearrangement, ε-caprolactam, S-1 zeolite, silanol