Chem. J. Chinese Universities

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Selective Catalytic Reduction of NO with Ammonia over Fe Promoted Mo/ZSM-5 Catalysts

LI Zhe, CHEN Bing, HUANG Wei, XIE Ke-Chang
  

  1. Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, China
  • Received:2005-12-08 Revised:1900-01-01 Online:2006-10-10 Published:2006-10-10
  • Contact: LI Zhe

Abstract: The Fe-Mo/ZSM-5 catalysts with different Fe/Mo molar ratios were prepared by using impregnation method. The activity of Fe-Mo/ZSM-5 catalysts for selective catalytic reduction of NO with ammonia and the effects of reaction conditions were also studied. It was found that Fe-Mo/ZSM-5 is more active than both of Mo/ZSM-5 and Fe/ZSM-5 separately, and it exhibits the best performance for SCR reaction when n(Fe)/n(Mo) ratio is 1.5, for which the highest NOx conversion reached 96% at the temperature of 430 ℃. The experiment results also show that Fe-Mo/ZSM-5 catalyst has a good stability of SCR reaction, for higher catalytic activity was gained under the condition of high space velocity and varied O2 concentrations. The bulk phase and surface structures were determined by XRD, XPS techniques respectively. The results show that there is a strong interaction among Fe, Mo and HZSM-5, and the surface Mo3d percentage is the largest when n(Fe)/n(Mo) ratio is 1.5, which may be related to its better catalytic performance for catalytic reduction of NO. It is also important to notice that NO2 was not detected during the XPS measurement, and NO was the main species during SCR reaction on the surface of Fe-Mo/ZSM-5 catalyst. From this it can be deduced that NO is directly reacted with ammonia to form nitrogen and water on the surface of the catalyst.

Key words: Fe-Mo/ZSM-5 catalyst, Molar ratio of Fe to Mo, Nitrogen monooxide, Selective catalytic reduction, Surface Mo3d percentage

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