Li改性MnO2及LiMn2O4催化NH3-SCR反应性能研究

孔志坚; 王成; 丁正南; 陈银飞; 张泽凯

Li改性MnO₂及LiMn₂O₄催化NH₃-SCR反应性能研究

浙江工业大学化学工程学院催化反应工程研究所, 浙江杭州 310014

详细信息

通讯作者:
张泽凯, Tel/Fax: (0571)88320767; E-mail: zzk@zjut.edu.cn。

中图分类号: X511
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出版历程
- 收稿日期: 2014-09-10
- 修回日期: 2014-11-05
- 刊出日期: 2014-12-30

Li-modified MnO₂ catalyst and LiMn₂O₄ for selective catalytic reduction of NO with NH₃

Institute of Chemical Reaction Engineering, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, China

摘要

摘要: 采用高温固相反应法、Pechini合成方法和柠檬酸配位法,制备了系列锂锰复合氧化物LiMn₂O₄催化剂,应用于NH₃-SCR反应,并与固相反应法合成的MnO₂进行了比较。采用N₂吸附-脱附、扫描电镜、X射线衍射、H₂程序升温还原、NH₃程序升温脱附、NO程序升温脱附和X射线光电子能谱对LiMn₂O₄催化剂进行表征。结果表明,引入Li有利于提高锰基催化剂的SCR活性和抗硫性。Pechini法制备LiMn₂O₄的NO转化率可在130~260 ℃达到90%以上;固相反应法制备LiMn₂O₄的NO转化率大于90%的温度为90~310 ℃;MnO₂的温度窗口则仅为140~280 ℃。与MnO₂相比,引入Li可形成LiMn₂O₄结构,因此,催化剂中更多的锰离子保持在相对较低的价态Mn³⁺,并调整表面活性氧含量;同时,Li的存在调变了LiMn₂O₄表面的酸位,从而减少高温下MnO₂表面容易发生的NH₃非选择性氧化,改善其催化NH₃-SCR反应的温度窗口,也增强了抗硫性。
- Li /
- LiMn₂O₄ /
- MnO₂ /
- 选择性催化还原 /
- 非选择性氧化
Abstract: LiMn₂O₄ prepared by high temperature solid state reaction, pechini, and citric acid coordination methods was applied in selective catalytic reduction (SCR) of NO with NH₃. MnO₂ prepared by high temperature solid state reaction method and the activity was tested as a comparsion. The catalysts were characterized by N₂ adsorption-desorption, scanning electron microscopy, X-ray diffraction, H₂ temperature-programmed reduction, NH₃ temperature-programmed desorption, NO temperature-programmed desorption, and X-ray photoelectron spectroscopy. The results showed that high-temperature activity of SCR were improved after the introduction of Li into MnO₂. NO conversion on the LiMn₂O₄ prepared by pechini method was above 90% in the range of 130~260 ℃; NO conversion on the LiMn₂O₄ by high temperature solid state reaction method could be kept above 90% in the range of 90~310 ℃; while the temperature window of MnO₂ was only 140~280 ℃. Compared with MnO₂, LiMn₂O₄ crystal structure not only keeps more manganese cations at a relatively low valence of Mn³⁺, but also adjusts surface active oxygen. Meanwhile, the existence of Li adjusts surface-acid sites of LiMn₂O₄, thus alleviates the unselective oxidation of NH₃ in the high temperature, broadens the operating temperature window of NH₃-SCR reaction, and improves the catalyst tolerance of SO₂.
- Li /
- LiMn₂O₄ /
- MnO₂ /
- selective catalytic reduction /
- unselective oxidation

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参考文献(30)

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