Acta Phys. -Chim. Sin. ›› 2001, Vol. 17 ›› Issue (07): 631-635.doi: 10.3866/PKU.WHXB20010712

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Structure Characterization of γ-Mo2N and Mo Nitrides Supported on Zeolites

Liu Zhen-Lin;Meng Ming;Fu Yi-Lu;Jiang Ming;Hu Tian-Dou;Xie Ya-Ning;Liu Tao   

  1. Department of Chemical Physics,University of Science and Technology of China,He fei 230026;Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100039
  • Received:2000-11-21 Revised:2001-03-31 Published:2001-07-15
  • Contact: Fu Yi-Lu E-mail:fulin@ustc.edu.cn

Abstract: Zeolites supported Mo nitrides were prepared via MoO3+NH3 reaction in temperature programmed mannar.The XRD data show that the frame structure of NaY and Na-ZSM-5 zeolites can still be maintained after nitridation at 973K.By an alysis of the extended X-ray absorption fine structure(EXAFS) of the Mo K-abso rption edge,the structural informations of both oxidic and nitrided Mo catalysts were obtained.The supported MoO3 samples show three peaks in the radial structu re function(RSF).The first two peaks correspond to the nearest Mo-O coordinatio n shell,but the ratio of the first peak to the second one is much larger than th at of the MoO3.This suggests that the MoO3 supported on zeolites has more compac t structure than the unsupported one.There are three peaks in the RSF of Mo2N,re presenting one Mo-N and two Mo-Mo shells,which is in good agreement with the f ace-centered cubic model.Calculation from X-ray diffraction data and EXAFS spe ctra reveals that the N atoms in Mo2N lengthen the distance between Mo atoms and weaken the Mo-Mo bond.Supported Mo2N samples give out nearly the same RSFs as the Mo2N,only the peak corresponding to Mo-N shell is weak,suggesting that the supported Mo2N has more structural disorder than the unsupported one.Mo2N suppor ted on Na-ZSM-5 gives out shorter coordination distance than supported on NaY, suggesting stronger interaction between Mo2N and Na-ZSM-5.

Key words: Zeolite supports, Molybdenum nitride catalysts, EXAFS, Structure