催化学报

催化学报 ›› 2006, Vol. 27 ›› Issue (3): 245-249.

• 研究论文 • 上一篇    下一篇

氢氟酸后处理对Silicalite-1催化环己酮肟气相Beckmann重排反应性能的影响

陶伟川1,2,毛东森2,夏建超2,陈庆龄1,2,胡英1   

  1. 1 华东理工大学化学与制药学院, 上海 200237; 2 中国石油化工股份有限公司上海石油化工研究院, 上海 201208
  • 收稿日期:2006-03-25 出版日期:2006-03-25 发布日期:1984-10-26

Effect of Hydrofluoric Acid Post-Treatments on Catalytic Performance of Silicalite-1 for Vapor-Phase Beckmann Rearrangement of Cyclohexanone Oxime

TAO Weichuan1,2, MAO Dongsen2*, XIA Jianchao2, CHEN Qingling1,2, HU Ying1   

  1. TAO Weichuan1,2, MAO Dongsen2*, XIA Jianchao2, CHEN Qingling1,2, HU Ying1
  • Received:2006-03-25 Online:2006-03-25 Published:1984-10-26

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摘要： 研究了氢氟酸后处理对 silicalite-1 催化环己酮肟气相Beckmann重排反应性能的影响. 结果表明,经适当浓度的氢氟酸溶液处理后,催化剂的选择性和稳定性都明显改善. 其中, silicalite-1 原粉先经硝酸铵预处理后再进行氢氟酸后处理所得到的催化剂催化性能最好,反应53 h后环己酮肟的转化率仍保持在96%左右,己内酰胺的选择性高达96.1%. XRD, FT-IR和 29Si MAS NMR的结果表明,较高的具有氢键相互作用的硅羟基与孤立硅羟基的比例值对环己酮肟气相Beckmann重排反应有利,同时, silicalite-1 表面硅原子的排布方式对该反应也有重要影响.

关键词: ilicalite-1 分子筛, 氢氟酸, 环己酮肟, 气相Beckmann重排, 己内酰胺

Abstract: This paper presents a novel modification of silicalite-1 with hydrofluoric acid treatment. Silicalite-1 treated with 0.04%HF solution exhibited remarkable improvements in stability and selectivity for Beckmann rearrangement of cyclohexanone oxime(CHO). Particularly, silicalite-1 catalyst with ammonium nitrate pre-treatment before HF modification showed the best catalytic performance: the conversion of CHO remained nearly 96% after 53 h reaction, and the selectivity for caprolactam during reaction was as high as 96.1%. XRD results showed that all samples hold the MFI structure after HF treatments, but the structural symmetry was changed from orthorhombic to monoclinic. FT-IR spectra revealed that the intensity of silanols, including isolated silanols and associated silanols on silicalite-1 catalysts, decreased severely after HF modification, while the ratio of associated silanols to isolated silanols became much higher. These results indicate that a high ratio of associated silanols to isolated silanols is favorable to the Beckmann rearrangement reaction. However, a 0.45%HF solution used in the modification led to a decrease in activity and selectivity because the arrangement of silicon atoms was greatly changed, which was proved by 29Si MAS NMR. It is inferred that the arrangement of silicon atoms on the surface of silicalite-1 is of significant importance to the catalytic performance of Beckmann rearrangement reaction.

Key words: silicalite-1, hydrofluoric acid, cyclohexanone oxime, vapor-phase Beckmann rearrangement, caprolactam