催化学报

催化学报 ›› 2010, Vol. 31 ›› Issue (9): 1107-1114.DOI: 10.1016/S1872-2067(10)60108-8

• 研究论文 • 上一篇    下一篇

富氧条件下 Mn/ZSM-5 选择催化 CH4 还原 NO

陈树伟 1, 闫晓亮 2, 陈佳琪 2, 马静红 2, 李瑞丰 1,2   

  1. 1 太原理工大学化学化工学院, 山西太原 030024 2 太原理工大学精细化工研究所, 煤科学与技术教育部重点实验室, 山西太原 000024
  • 收稿日期:2010-09-30 出版日期:2010-09-30 发布日期:2014-01-25

Selective Catalytic Reduction of NO in Excess Oxygen by Methane over Mn/ZSM-5 Catalysts

CHEN Shuwei1, YAN Xiaoliang2, CHEN Jiaqi2, MA Jinghong2, LI Ruifeng1,2,*   

  1. 1College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China 2Key Laboratory of Coal Science and Technology for Ministry of Education, Institute of Special Chemicals, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China
  • Received:2010-09-30 Online:2010-09-30 Published:2014-01-25

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摘要： 考察了富氧条件下 Mn/ZSM-5 催化剂上 CH4 选择催化还原 NO 反应, 并采用 H2程序升温还原、SO2程序升温表面反应和 NO程序升温脱附等手段对催化剂进行了表征. 结果表明, 催化剂活性与制备方法和 Mn 负载量密切相关. 离子交换法制备的 Mn/ZSM-5 催化剂活性明显优于浸渍法制备的催化剂; NO 转化率随着 Mn 负载量的增加而增加, 至 2.06% 时达到最大值 (57.3%), 然后随着 Mn 负载量的增加而降低. 采用离子交换法或较低 Mn 负载量 (≤ 2.06%) 抑制了催化剂中非化学计量的 MnOx (1.5 < x < 2) 物种的形成, 减缓了 CH4 的氧化燃烧反应, 因而 CH4 还原 NO 的选择性提高. 在含 SO2 体系中, Mn/ZSM-5 活性在 550 oC 以下时明显下降, 但在 600 oC 以上基本不受影响. 这是由于在 550 oC 以下时 SO2 在 Mn/ZSM-5 表面形成了稳定的吸附硫物种, 覆盖了部分活性位, 导致催化剂活性降低; 而在 600 oC 以上时含硫物种基本脱附完全, 因而对催化剂活性影响不大.

关键词: 一氧化氮, 甲烷, 选择催化还原, 锰, ZSM-5, 二氧化硫

Abstract: The selective catalytic reduction of NO in excess O2 by CH4 was investigated over a series of ZSM-5-supported manganese catalysts (Mn/ZSM-5). The catalytic activity depended on preparation method and Mn loading. An ion exchange method resulted in a higher activity than an impregnation method. Catalytic activity increased with increasing Mn loading until a Mn loading of 2.06% that gave a maximum NO conversion of 57.3%. H2 temperature-programmed reduction results showed that the ion exchange method and low Mn loadings (≤ 2.06%) restricted the formation of non-stoichiometric MnOx (1.5 < x < 2) species that have higher oxidative activity, and thus suppressed the combustion of CH4 by O2, which increased the selectivity for NO reduction. In a SO2 containing stream, a substantial decrease in NO conversion was seen at ≤ 550 oC but not at ≥ 600 oC. SO2 temperature-programmed surface reaction and NO temperature-programmed desorption demonstrated that sulfur species were formed at temperature ≤ 550 oC, and these covered active sites and decreased the catalytic activity. The sulfur species desorbed at ≥ 600 oC, thus the addition of SO2 did not have a significant impact on the catalytic activity.

Key words: nitrogen oxide, methane, selective catalytic reduction, manganese, ZSM-5, sulfuric dioxide