低温下NH3选择性催化还原NOx的MnOx/TiO2催化剂的温敏长期稳定性

IF 2.5 3区 化学 Q2 CHEMISTRY, MULTIDISCIPLINARY
Ruoxuan Bai, Rongkun Jiang, Zixiao Yu, Junqi Wang, Yiqing Zeng and Shule Zhang
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引用次数: 0

摘要

为了提高MnOx基催化剂在低温下的NH3-SCR活性,人们做了很多努力,但对其长期稳定性的研究却很少。本研究通过湿浸渍法制备MnOx/TiO2 (MnTi)催化剂,在实验室条件下进行了30 h的长期稳定性测试,考察其在低温(80-200℃)下选择性催化还原(NH3-SCR) NOx的稳定性,并结合XRD、BET、XPS、H2-TPR和原位DRIFTS分析来阐明失活机理。结果表明,反应温度对硝酸盐的生成、分解和转化有很大的影响。在较低温度下(本研究≤160℃),硝酸盐,尤其是稳定的硝酸盐在催化剂表面不断积累,可能会阻断活性位点,阻碍Mn3+向Mn4+的转化,从而导致MnTi催化剂失活。相反,催化剂表面的硝酸盐在足够高的温度下(本研究≥200℃)可以快速反应或分解,有利于活性位点的暴露和Mn4+/Mn3+氧化还原循环的动态平衡,从而具有较高的长期稳定性。希望本工作能引起研究者在提高NH3-SCR催化剂低温催化活性的研究中对其长期稳定性的关注。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Temperature sensitive long-term stability of MnOx/TiO2 catalysts for selective catalytic reduction of NOx with NH3 at low temperature†

Temperature sensitive long-term stability of MnOx/TiO2 catalysts for selective catalytic reduction of NOx with NH3 at low temperature†

A number of efforts have been made to improve the NH3-SCR activity of MnOx based catalysts at low temperature, but few studies have focused on their long-term stability. In this study, MnOx/TiO2 (MnTi) catalysts prepared via wet impregnation were subjected to 30-h long-term stability tests under laboratory conditions to investigate their stability for the selective catalytic reduction (NH3-SCR) of NOx at low temperatures (80–200 °C), and combined with XRD, BET, XPS, H2-TPR, and in situ DRIFTS analysis to elucidate deactivation mechanisms. The results show that the reaction temperature has a great influence on the formation, decomposition, and transformation of nitrate species. Nitrate species, especially stable nitrate species, continuously accumulate on the catalyst surface at relatively low temperatures (≤160 °C in this work), which might block the active sites and hinder the conversion of Mn3+ to Mn4+, thereby leading to deactivation of the MnTi catalyst. In contrast, nitrate species on the catalyst surface can react or decompose rapidly at a high enough temperature (≥200 °C in this work), which facilitates the exposure of active sites and dynamic equilibrium of the Mn4+/Mn3+ redox cycle, resulting in the high long-term stability. We expect that this work will arouse researchers’ attention toward the long-term stability of NH3-SCR catalysts in the study of improving their catalytic activity at low temperature.

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来源期刊
New Journal of Chemistry
New Journal of Chemistry 化学-化学综合
CiteScore
5.30
自引率
6.10%
发文量
1832
审稿时长
2 months
期刊介绍: A journal for new directions in chemistry
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