物理化学学报 >> 2005, Vol. 21 >> Issue (08): 898-902.doi: 10.3866/PKU.WHXB20050815

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DFT法研究分子筛催化trans-2-丁烯的双键异构

李会英; 蒲敏; 陈标华   

  1. 北京化工大学可控化学反应科学与技术基础教育部重点实验室, 北京 100029
  • 收稿日期:2004-12-30 修回日期:2005-03-04 发布日期:2005-08-15
  • 通讯作者: 蒲敏 E-mail:pumin@mail.buct.edu.cn

DFT Study on Double-bond Isomerization of trans-2-butene Catalyzed by Zeolites

LI Hui-ying; PU Min; CHEN Biao-hua   

  1. Key Laboratory for Science and Technology of Controllable Chemical Reaction of Ministry of Education, Beijing University of Chemical Technology, Beijing 100029
  • Received:2004-12-30 Revised:2005-03-04 Published:2005-08-15
  • Contact: PU Min E-mail:pumin@mail.buct.edu.cn

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摘要： 利用一个3T簇模型模拟分子筛催化剂的酸性位, 采用密度泛函理论(DFT)的 B3LYP/6-31G(d, p)方法, 研究了分子筛催化1-丁烯双键异构为trans-2-丁烯的反应机理. 对反应各驻点进行了全优化, 经过零点能校正后, 得到了反应的活化能. 研究表明, 反应分三步进行：物理吸附→化学反应→物理脱附. 分子筛的酸性位OH基团首先吸附1-丁烯的双键形成了π配位复合物, 然后按协同反应机理发生双键异构反应, 生成吸附态的trans-2-丁烯, 最后脱附成产物. 计算得到的表观活化能为57.1 kJ•mol-1, 与实验结果接近.

关键词: 分子筛, 丁烯, 双键异构, 密度泛函理论, 过渡态

Abstract: Using density functional theory(DFT), the double-bond isomerization of 1-butene to trans-2-butene over zeolites is investigated with a 3T cluster model simulating zeolite. At the B3LYP/6-31G(d, p) level, the complete geometry optimization and the activation energy calculation are performed with a EZP correction. It is found that the process include three steps, physical adsorption→chemical reaction→physical desorption. Firstly, the OH group of the acidic site of zeolite adsorbs the double-bond of 1-butene and forms a π-complex. Secondly, the double-bond isomerization reaction shows a concerted mechanism and yields the adsorbed trans-2-butene. Lastly, trans-2-butene is produced by desorption and the zeolite active site is restored. The calculated apparent activation energy is 57.1 kJ•mol-1, which is in agreement with the experimental data.

Key words: Zeolite, Butene, Double-bond isomerization, Density functional theory, Transition state