物理化学学报 >> 2008, Vol. 24 >> Issue (03): 369-374.doi: 10.1016/S1872-1508(08)60016-9

研究论文 上一篇    下一篇

Pt/Si-MCM-41介孔结构对低温NO+H2+O2反应的影响

武鹏; 刘运霞; 章福祥; 李兰冬; 杨雅莉; 关乃佳   

  1. 南开大学化学学院新催化材料研究所, 天津 300071
  • 收稿日期:2007-09-19 修回日期:2007-11-20 发布日期:2008-03-10
  • 通讯作者: 关乃佳 E-mail:guannj@nankai.edu.cn

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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摘要： 将Pt/Si-MCM-41用于H2选择催化还原(H2-SCR)消除NO的反应. X射线衍射分析、N2吸附/脱附、氢吸附和透射电镜等分析结果表明，介孔Si-MCM-41具有大的比表面积和孔体积有利于活性组分Pt的分散, Pt/Si-MCM-41催化剂在富氧和80000 h-1空速的条件下，其H2-SCR低温活性在100 ℃达到60.1%，优于Pt/Si-ZSM-5和Pt/SiO2催化剂，其选择性在120 可达70%. 当Si-MCM-41的介孔结构被破坏时，H2-SCR反应活性明显下降，最大活性在120 ℃仅为15%. 漫反射红外光谱(DRIFTS)测试表明, —NO3物种是Pt/Si-MCM-41催化剂在H2-SCR反应中的主要中间物种.

关键词: H2-SCR, NO, 富氧, Si-MCM-41, 低温, DRIFTS

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