Acta Phys. -Chim. Sin. ›› 2001, Vol. 17 ›› Issue (02): 111-115.doi: 10.3866/PKU.WHXB20010204

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DFT Study on the Active Sites in Mn-Na2WO4/SiO2 Catalyst

Chen Hong-Shan;Niu Jian-Zhong;Zhang Bing;Li Shu-Ben   

  1. Department of Physics ,Northwest Normal University,Lanzhou 730070; State Key Laboratory for Oxo Synthesis and Selective Oxidation,Lanzhou Institute of Chemical Physics,Lanzhou 730000
  • Received:2000-05-09 Revised:2000-07-21 Published:2001-02-15
  • Contact: Chen Hong-Shan E-mail:chenhs@nwnu.edu.cn

Abstract: MnNa2WO4/SiO2 is one of the best catalysts for oxidative coupling of methane.To investigate the nature of active centers and the reaction mechanism,the structure of possible metal sites formed by tungsten and manganese over the silica surface were studied using molecular simulation method and ab initio DFT calculations.Silica support exists in the catalyst as 岐瞔ristobalite and its (111) face exposes preferentially to the surface.The calculated results show that tungsten interacts with the silica surface by three or one bridge oxygen atoms to form tetrahedral [WO4],and manganese interacts with single bridge oxygen to form dispersed [MnO4] or exists as oxide clusters.The nature of the molecular orbitals and the electronic structure suggest that the tetrahedral [WO4] site with single bridge oxygen is the most probable active center responsible for methane activation.

Key words: Mn-Na2WO4/SiO2, Active sites, DFT