物理化学学报 >> 2004, Vol. 20 >> Issue (08S): 1024-1031.doi: 10.3866/PKU.WHXB200408zk20

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低碳烷烃催化反应机理的固体核磁共振研究

贺鹤勇;邹艳;马卓娜;岳斌   

  1. 复旦大学化学系,上海市分子催化和功能材料重点实验室,上海 200433
  • 收稿日期:2004-02-16 修回日期:2004-04-01 发布日期:2004-08-15
  • 通讯作者: 贺鹤勇 E-mail:heyonghe@fudan.edu.cn

In situ MAS NMR Spectroscopy Study on Catalytic Reaction Mechanism of Light Alkanes

He He-Yong;Zou Yan;Ma Zhuo-Na;Yue Bin   

  1. Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433
  • Received:2004-02-16 Revised:2004-04-01 Published:2004-08-15
  • Contact: He He-Yong E-mail:heyonghe@fudan.edu.cn

摘要: 结合实验研究,介绍了13C原位固体核磁共振技术及其在催化反应机理研究中的应用,主要工作包括温和条件下丙烷在镓改性H-ZSM-5上的活化研究,SO42-/ZrO2、CsxH3-xPW12O40和H-MOR催化剂上正丁烷的异构化反应机理研究,以及利用原位13C MAS NMR测定催化剂超强酸性.

关键词: 原位, 固体核磁共振, 机理, 催化反应, 低碳烷烃

Abstract: In situ MAS NMR spectroscopy has been successfully applied to study catalytic reaction mechanisms. Examples taken from our own study illustrate that the batch-like condition in situ MAS NMR technique with strategically 13C labeled reactants can contribute to the understanding of reaction pathway. The results indicate that the ion-exchanged and/or its related Ga species are the highly active catalytic components for the activation of propane under mild condition over Ga-modified H-MFI catalysts. Reaction mechanism of skeletal isomerization of n-butane over a series of solid acid catalysts in the acidic strength order of SO42-/ZrO2, CsxH3-xPW12O40 and H-MOR was also studied. The mechanism of n-butane isomerization is dependent on the type of solid acid catalyst. Under low temperature, n-butane isomerization on SO42-/ZrO2 and CsxH3-xPW12O40 catalysts proceeds through a monomolecular pathway in the initial stage of the reaction. At the later stage, C3 and C5 are detected, giving the evidence of the contribution of the bimolecular process. On H-MOR catalyst, n-butane isomerization occurs primarily via a bimolecular pathway. Further study shows that the kinetics of n-butane isomerization on SO42-/ZrO2 catalyst at ambient temperature can be well represented by Langmuir-Hinshelwood equation for a reversible first order surface reaction. The calculated isomerization reaction rate constant can be used as a measure of the solid superacidity of the catalysts.

Key words: In situ, Solid state NMR, Mechanism, Catalytic reaction, Light alkanes