物理化学学报 >> 2014, Vol. 30 >> Issue (11): 2063-2070.doi: 10.3866/PKU.WHXB201409221

理论与计算化学 上一篇    下一篇

噻吩在γ-Mo2N(100)表面上加氢脱硫反应的密度泛函理论研究

徐坤, 冯杰, 褚绮, 张丽丽, 李文英   

  1. 太原理工大学, 煤科学与技术省部共建国家重点实验室培育基地, 太原 030024
  • 收稿日期:2014-06-20 修回日期:2014-09-22 发布日期:2014-10-30
  • 通讯作者: 冯杰, 李文英 E-mail:fengjie@tyut.edu.cn;ying@tyut.edu.cn
  • 基金资助:

    国家高技术研究发展计划项目(863) (2011AA05A204)资助

Density Functional Theory Study of Thiophene Hydrodesulfurization on γ-Mo2N(100) Surface

XU Kun, FENG Jie, CHU Qi, ZHANG Li-Li, LI Wen-Ying   

  1. Training Base of State Key Laboratory of Coal Science and Technology Jointly Constructed by Shanxi Province and Ministry of Science and Technology, Taiyuan University of Technology, Taiyuan 030024, P. R. China
  • Received:2014-06-20 Revised:2014-09-22 Published:2014-10-30
  • Contact: FENG Jie, LI Wen-Ying E-mail:fengjie@tyut.edu.cn;ying@tyut.edu.cn
  • Supported by:

    The project was supported by the National High Technology Research and Development Program of China (863) (2011AA05A204).

摘要:

利用密度泛函理论研究了γ-Mo2N(100)表面上的噻吩加氢脱硫(HDS)过程. 噻吩在γ-Mo2N(100)表面上不同作用形式的结构优化结果显示, η5-Mo2N吸附构型最稳定, 具有最大的吸附能(-0.56 eV), 此时噻吩通过S原子与Mo2原子相连平行表面吸附在四重空位(hcp 位). H原子和噻吩在hcp位发生稳定共吸附, hcp位是噻吩HDS的活性位点. 噻吩在γ-Mo2N(100)表面进行直接脱硫反应, HDS过程分为S原子脱除和C4产物加氢饱和两部分. 过渡态搜索确定了HDS最可能的反应机理及中间产物, 首个H原子的反应需要最大的活化能(1.69 eV),是噻吩加氢脱硫的控速步骤. 伴随H原子的不断加入, 噻吩在γ-Mo2N(100)表面上优先生成―SH和丁二烯, 随后―SH加氢生成H2S, 丁二烯加氢饱和生成2-丁烯和丁烷. 由于较弱的吸附, H2S、2-丁烯和丁烷很容易在γ-Mo2N(100)表面脱附成为产物.

关键词: 噻吩, 氮化钼, 加氢脱硫, 反应机理, 密度泛函理论

Abstract:

The hydrodesulfurization (HDS) of thiophene on an γ-Mo2N(100) surface was investigated by density functional theory (DFT) and different configurations of thiophene on γ-Mo2N(100) surface were considered. After geometric optimization, it was confirmed that the η5-Mo2N configuration was the most stable adsorption model with an adsorption energy of -0.56 eV, where thiophene absorbed on 4-fold hcp vacant sites parallel to the surface with the S atom bonded to a Mo2 atom. The stable coadsorption of H atoms and thiophene on hcp sites showed that the hcp site is the active site for thiophene HDS on γ-Mo2N(100). A direct desulfurization reaction pathway in HDS of thiophene dominated the process on the γ-Mo2N(100) surface, which could be divided into the removal of the S atom and the hydrogenation saturation of C4 species. To identify the intermediate products and the most probable reaction mechanism of thiophene HDS, a transition state search was carried out. The results indicated that the reaction of the first H atom required an activation energy of 1.69 eV, which was the rate-determining step in the HDS of thiophene. The thiol group (―SH) and butadiene were preferentially formed after hydrogenation of thiophene, and ―SH detached from mercaptan was the intermediate of H2S. 2-Butene and butane were the products of the hydrogenation saturation of butadiene. H2S, 2-butene, and butane were easily desorbed from γ-Mo2N(100) to give the products because of weak adsorption.

Key words: Thiophene, Molybdenum nitride, Hydrodesulfurization, Reaction mechanism, Density functional theory

MSC2000: 

  • O641