Chinese Journal of Catalysis

Chinese Journal of Catalysis ›› 2010, Vol. 31 ›› Issue (10): 1233-1241.DOI: 10.1016/S1872-2067(10)60117-9

• Research papers • Previous Articles     Next Articles

Adsorption-Oxidation Reaction Mechanism of NO on Na-ZSM-5 Molecular Sieves with a High Si/Al Ratio at Ambient Temperature

LIU Huayan1,2, ZHANG Zekai2, XU Yuanyuan2, CHEN Yinfei2,*, LI Xi1   

  1. 1Department of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang, China;2College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014, Zhejiang, China
  • Received:2010-10-25 Online:2010-10-25 Published:2014-03-04

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Abstract: The oxidation reaction mechanism of NO by O2 over Na-ZSM-5 molecular sieves with a high SiO2/Al2O3 ratio was studied at ambient temperature by temperature-programmed surface reaction (TPSR) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results show that the NO catalytic oxidation process is accompanied by a significant adsorption of NO2 and it exhibits a dynamic equilibrium between NO2 adsorption and the reaction of NO. TPSR and in situ DRIFTS characterization of the adsorbed NOx species revealed that adsorbed NO3 formed on the surface of the Na-ZSM-5 molecular sieve as a result of the reaction between adsorbed NO and gaseous O2. The oxidation of NO3 with NO produced weakly-adsorbing NO2 and N2O4 which were released once the adsorption reached saturation. Therefore, the strongly-adsorbing NO3 was an intermediate of the NO oxidation reaction and its presence promoted NO adsorption.

Key words: Na-ZSM-5 molecular sieve, nitric oxide, oxidation, nitrogen oxide, adsorption, removal