物理化学学报 >> 2010, Vol. 26 >> Issue (11): 3009-3016.doi: 10.3866/PKU.WHXB20101120

催化和表面结构 上一篇    下一篇

低温NH3-SCR催化剂MnOx-CeOx/ACF的SO2中毒机理

沈伯雄, 刘亭   

  1. 南开大学环境科学与工程学院, 天津300071
  • 收稿日期:2010-04-12 修回日期:2010-08-02 发布日期:2010-10-29
  • 通讯作者: 沈伯雄 E-mail:shenbx@nankai.edu.cn
  • 基金资助:

    国家自然科学基金(50976050), 新世纪优秀人才支持计划(07-0457)和天津市科技支撑计划项目(09ZCKFSH01900)资助

Deactivation of MnOx-CeOx/ACF Catalysts for Low-Temperature NH3-SCR in the Presence of SO2

SHEN Bo-Xiong, LIU Ting   

  1. College of Environmental Science and Engineering, Nankai University, Tianjin 300071, P. R. China
  • Received:2010-04-12 Revised:2010-08-02 Published:2010-10-29
  • Contact: SHEN Bo-Xiong E-mail:shenbx@nankai.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (0976050), Programfor NewCentury Excellent Talents in University, China (07-0457) and National Key Technology Research and Development Programof Tianjin, China (09ZCKFSH01900).

摘要:

在二氧化硫(SO2)气氛下, 对Fe、Cu 和V 改性的催化剂MnOx-CeOx/ACF(活性碳纤维)的氨选择性催化还原(NH3-SCR)一氧化氮的低温活性进行研究. 实验结果表明: 以Cu 和V 改性催化剂未提高MnOx-CeOx/ACF 的低温抗SO2性能; Fe 改性MnOx-CeOx/ACF 在初始6 h 内提高了催化剂的抗SO2性能, 但较长时间仍然失活. 以N2吸附、X射线光电子能谱(XPS)、傅里叶变换红外(FT-IR)光谱以及热重分析(TGA)等手段对中毒催化剂进行分析. 在SO2存在下, 催化剂中毒归因于两个方面:一是覆盖于催化剂表面的铵盐类物质, 二是SO2与催化剂中的金属氧化物反应生成的金属硫酸盐及亚硫酸盐. 在中毒催化剂中硫元素主要以金属硫酸盐及亚硫酸盐的形式存在, 其在中毒的MnOx-CeOx/ACF、Fe-MnOx-CeOx/ACF、Cu-MnOx-CeOx/ACF 和V-MnOx-CeOx/ACF 催化剂中所占比例分别为70.4%、68.9%、86.3%和71.4%(w). 进一步揭示了MnOx-CeOx/ACF 催化剂在低温SCR 条件下的SO2中毒机理.

 

关键词: 低温选择性催化还原, MnOx-CeOx/ACF, NO, SO2

Abstract:

The low-temperature selective catalytic reduction of NO with NH3 (NH3-SCR) over MnOx-CeOx/ACF (activated carbon fiber) modified by Fe, Cu, or V was investigated in the presence of SO2. The results revealed that the SO2 tolerance of MnOx-CeOx/ACF was not enhanced after Cu and V modification. The addition of Fe to MnOx-CeOx/ ACF enhanced its resistance to SO2 poisoning over the first 6 h in the presence of SO2, but then deactivated quickly. The samples were analyzed by N2 adsorption, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT- IR) spectroscopy, and thermogravimetric analysis (TGA).We found that catalyst surface coverage by ammoniumsalts as well asmetallic sulfates and sulfites formed by the reaction between SO2 and metal oxides in the catalysts was responsible for catalyst deactivation in the presence of SO2. Sulfur on the surface of the deactivated catalysts was mainly in the form of metallic sulfates and sulfites with 70.4%, 68.9%, 86.3%, and 71.4%(w) on deactivated MnOx-CeOx/ACF, Fe- MnOx-CeOx/ACF, Cu-MnOx-CeOx/ACF, and V-MnOx-CeOx/ACF, respectively. A valuable contribution towards understanding the deactivation of catalysts based on MnOx-CeOx/ACF for the SCR in the presence of SO2 was made.

 

Key words: Low-temperature selective catalytic reduction, MnOx-CeOx/ACF, NO, SO2

MSC2000: 

  • O643