Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (11): 2063-2070.doi: 10.3866/PKU.WHXB201409221

• THEORETICAL AND COMPUTATIONAL CHEMISTRY • Previous Articles     Next Articles

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).

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