催化学报

催化学报 ›› 2006, Vol. 27 ›› Issue (8): 664-670.

• 研究论文 • 上一篇    下一篇

吡啶在H-MOR分子筛孔道中吸附的量子化学研究

袁淑萍1,2,段云波1,王建国2,李永旺2,焦海军2   

  1. 1 青岛大学计算科学与工程技术研究中心, 山东青岛 266071; 2 中国科学院山西煤炭化学研究所煤转化国家重点实验室, 山西太原 030001
  • 收稿日期:2006-08-25 出版日期:2006-08-25 发布日期:2010-09-28

Study on Pyridine Adsorption in H-MOR by Quantum Chemistry

YUAN Shuping1, 2*, DUAN Yunbo1, WANG Jianguo2, LI Yongwang2, JIAO Haijun2   

  1. 1 Institute for Computational Science and Engineering, Qingdao University, Qingdao 266071, Shandong, China; 2 State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, The Chinese Academy of Sciences, Taiyuan 030001, Shanxi, China
  • Received:2006-08-25 Online:2006-08-25 Published:2010-09-28

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957

被引次数

29

摘要： 用24T模型和两种ONIOM2方法(QM/QM和QM/MM)研究了杂原子H-AlMOR和H-BMOR分子筛的结构、酸性及其对吡啶的吸附性能. 吸附热以及分子筛的几何结构和电子结构数据表明, H-BMOR的B酸性远远弱于H-AlMOR, 因此二者可分别应用于对酸性要求不同的催化反应. 采用QM/QM计算得到的吡啶在H-AlMOR上的吸附热(219.3 kJ/mol)与实验结果(200 kJ/mol)比较接近. QM/QM方法尽管耗时较多,但能得到更精确的结果,而QM/MM方法可用于定性研究及对模型结构的初步预测. 吸附复合物的结构参数及红外振动频率等数据表明,吡啶在两种分子筛上吸附时均发生了质子转移,生成PyH+…ZeO-离子对. 此外,吸附复合物中还存在多重氢键作用.

关键词: 丝光沸石, 吡啶, 吸附, ONIOM方法, 量子化学

Abstract: The structure and Bronsted acidity of H-AlMOR and H-BMOR as well as their adsorption for pyridine probe molecule were investigated by using a 24T cluster containing a two-layered 12-membered ring and ONIOM2 (QM/QM and QM/MM) hybride methods. The Bronsted acidity of H-AlMOR is stronger than that of H-BMOR. Pyridine adsorption energy on H-AlMOR of 219.3 kJ/mol calculated by ONIOM2 (QM/QM) method compares well with the experimental result of 200 kJ/mol. In addition, the structure and IR stretching frequencies of the adsorption complexes shows that proton transfer occurrs during the pyridine adsorption, and the PyH+…ZeO- ion pairs are further stabilized by multiple hydrogen bonding between the hydrogen atoms of pyridine and the framework oxygen atoms of the zeolite.

Key words: mordenite, pyridine, adsorption, ONIOM method, quantum chemistry