In situ FT-IR studies on low temperature NH3-SCR mechanism of NOx over MnOx/WO3/TiO2 catalyst

LIAO Yongjin; ZHANG Yaping; YU Yuexi; LI Juan; GUO Wanqiu; WANG Xiaolei

doi:10.11949/j.issn.0438-1157.20160953

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In situ FT-IR studies on low temperature NH₃-SCR mechanism of NO_x over MnO_x/WO₃/TiO₂ catalyst

更新时间：2025-11-26

- In situ FT-IR studies on low temperature NH₃-SCR mechanism of NO_x over MnO_x/WO₃/TiO₂ catalyst
- CIESC Journal Issue 12, Pages: 5031-5039(2016)
- 作者机构：
  
  1. 广东电网有限责任公司电力科学研究院,广东,广州,510080
  2. 东南大学能源与环境学院, 能源热转换及其过程测控教育部重点实验室,江苏,南京,210096
- 作者简介：
- 基金信息：
- DOI：10.11949/j.issn.0438-1157.20160953
  CLC： B34
- Online First：05 December 2016，
  
  Published：05 December 2016
- 稿件说明：
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LIAO Yongjin, ZHANG Yaping, YU Yuexi, et al. In situ FT-IR studies on low temperature NH₃-SCR mechanism of NO_x over MnO_x/WO₃/TiO₂ catalyst[J]. CIESC Journal, 2016, (12): 5031-5039. DOI: 10.11949/j.issn.0438-1157.20160953.
DOI：

LIAO Yongjin, ZHANG Yaping, YU Yuexi, et al. In situ FT-IR studies on low temperature NH₃-SCR mechanism of NO_x over MnO_x/WO₃/TiO₂ catalyst[J]. CIESC Journal, 2016, (12): 5031-5039. DOI: 10.11949/j.issn.0438-1157.20160953. DOI：

摘要

浸渍法制备15% MnOx/5% WO3/TiO2低温脱硝催化剂，利用原位傅里叶变换红外（in situ FT-IR）设计包括多种吸附反应以及不同预处理方式的微观暂态试验与微观稳态试验，研究其NH3-SCR脱硝反应机理，并推测反应路径。结果表明，催化剂的NH3-SCR反应主要以Eley-Rideal机理方式进行，仅在一定温度条件下可以看到Langmuir-Hinshclwood反应路径。催化剂表面Lewis酸位的NH3吸附是还原剂的主要来源，Brønsted酸位吸附的NH4+随温度上升参与反应的比例略有提高。NH3的吸附活化是整个反应的控制步骤，吸附态NH3更易与NO2发生反应，NO与催化剂表面的相互作用明显弱于NO2。NO会在催化剂表面氧化活性中心形成大量双齿配位型硝酸盐，阻碍NH3的吸附和活化，O2存在条件下促进NH3-SCR反应进行，阻止NO在催化剂表面形成双齿硝酸盐。NO与NH3在催化剂表面存在吸附竞争，NO的吸附作用强于NH3，温度达到100℃后吸附的NH3方可大量活化并与NOx发生进一步反应。

Abstract

15% MnOx/5% WO3/ TiO2 catalyst for low-temperature selective catalytic reduction of NOx was synthesized by an impregnation method. NH3-SCR mechanism was explored systematically and possible pathway was proposed through in situ FT-IR study on microscopic transient and steady states under various conditions of single or mixed gas feed with multiple pre-treatment. The results revealed that NH3-SCR reaction over the 15%MnOx/5%WO3/TiO2 catalyst proceeded mainly by the Eley-Rideal mechanism with the Langmuir-Hinshclwood pathway only at certain temperature. NH3 adsorbed on the Lewis acid sites of the catalyst surface was the main source of reductant; however

more NH4+ adsorbed on the Brønsted acid sites of the catalyst surface involved in the NOx reduction with increase of reaction temperature. The adsorption and activation of NH3 was key step for the whole SCR reaction. NO2 easily reacted with adsorbed NH3 with stronger affinity to catalyst surface than NO. The bidentate nitrate

which formed considerably at oxidation active centers of the catalyst by NO adsorption

didn't participate in NH3-SCR reaction but obstructed adsorption and activation of NH3. O2 could promote NH3-SCR by blocking formation of bidentate nitrate. The adsorption of NO and NH3 on the catalyst surface was competitive at room temperature

which NO adsorption was higher than NH3 at O2 absence. The absorbed NH3 could be massively activated and reacted with NOx upon temperature reached to 100℃.

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