Acta Phys. -Chim. Sin. ›› 2008, Vol. 24 ›› Issue (03): 369-374.doi: 10.1016/S1872-1508(08)60016-9

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Influences of Mesoporous Structure on the NO+H2+O2 Low Temperature Reaction over Pt/Si-MCM-41 Catalyst

WU Peng; LIU Yun-Xia; ZHANG Fu-Xiang; LI Lan-Dong; YANG Ya-Li; GUAN Nai-Jia   

  1. Institute of New Catalytic Materials Science, College of Chemistry, Nankai University, Tianjin 300071, P. R. China
  • Received:2007-09-19 Revised:2007-11-20 Published:2008-03-10
  • Contact: GUAN Nai-Jia E-mail:guannj@nankai.edu.cn

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Abstract: It was found that Si-MCM-41 mesoporous molecular sieves as a support of noble metal Pt could be used for the selective catalytic reduction of NO by hydrogen (H2-SCR) under lean-burn conditions. Pt/Si-MCM-41, together with Pt/Si-ZSM-5 and Pt/SiO2, was characterized by X-ray diffraction analysis (XRD), nitrogen adsorption/desorption, hydrogen adsorption, and transmission electron microscopy (TEM). The results indicated that Pt/Si-MCM-41 had the best H2-SCR activity in comparison with Pt/Si-ZSM-5 and Pt/SiO2 catalysts and that the maximum conversion of NO was up to 60.1%at 100 ℃ and a gas hourly space velocity (GHSV) of 80000 h-1 under lean-burn conditions. Characterization showed that the large surface area and pore volume of MCM-41 favored the dispersion of Pt. The maximum NO conversion of Pt/Si-MCM-41 catalyst decreased obviously to 15% at 120 ℃ when the pore structure of Si-MCM-41 support was destroyed. The reaction mechanism over Pt/Si-MCM-41 was investigated using in situ diffuse reflectance infrared spectroscopy (DRIFTS), which revealed that the main reaction intermediates should be nitrate species during NO reduction.

Key words: H2-SCR, NO, Excess oxygen, Si-MCM-41, Low temperature, DRIFTS