高等学校化学学报 ›› 2019, Vol. 40 ›› Issue (7): 1447-1455.doi: 10.7503/cjcu20190091

• 物理化学 • 上一篇    下一篇

Cr负载V2O5-WO3/TiO2催化剂的低温NH3-SCR脱硝活性

李春晓, 李坚(), 梁文俊, 梁全明   

  1. 北京工业大学区域大气复合污染防治北京市重点实验室, 北京 100124
  • 收稿日期:2019-02-01 出版日期:2019-07-10 发布日期:2019-07-12
  • 作者简介:李 坚, 男, 博士, 教授, 博士生导师, 主要从事酸雾治理、 挥发性有机物及NOx污染控制方面的研究. E-mail: ljian@bjut.edu.cn
  • 基金资助:
    国家重点研发计划项目(批准号: 2017YFC0210303-02)资助.

Low Temperature NH3-SCR Activity of Cr Doped V2O5-WO3/TiO2 Catalyst

LI Chunxiao, LI Jian*(), LIANG Wenjun, LIANG Quanming   

  1. Key Laboratory of Beijing on Regional Air Pollution Control, Beijing University of Technology, Beijing 100124, China
  • Received:2019-02-01 Online:2019-07-10 Published:2019-07-12
  • Contact: LI Jian E-mail:ljian@bjut.edu.cn
  • Supported by:
    † Supported by the National Key R&D Program of China(No.2017YFC0210303-02).

摘要:

采用浸渍法制备了一系列不同Cr负载量的CrOx-V2O5-WO3/TiO2催化剂, 研究了Cr改性对该催化剂脱硝活性及抗硫性能的影响. 结果表明, Cr的引入使V2O5-WO3/TiO2催化剂的低温NOx去除效果和抗硫性能显著提升. Cr的负载量为3%(以Cr2O3计算质量分数)时, 催化剂具有最佳的低温脱硝活性和N2选择性. 结构表征结果表明, 改性催化剂中Cr元素主要以Cr3+形式存在, Cr的引入使催化剂的氧化性能明显提升, 并使表面弱酸位点、 强酸位点和催化剂表面吸附氧数量增多. XPS分析结果表明, Cr能使催化剂中V5+/V4+比例降低, 促进催化剂中自由电子的迁移. In situ DRIFTs表征结果显示, Cr的引入能促进NO与吸附在Brönsted酸位点上的NH3在低温条件下反应, 从而使催化剂具有更好的低温脱硝活性. UV-Vis光谱分析结果表明, CrOx负载量提高会显著增加高价态Cr的烧结聚集. 同时, 提出了一种选择性催化还原(SCR)反应中Cr-V协同催化的机理.

关键词: 选择性催化还原, Cr改性, 低温脱硝活性

Abstract:

A series of different contents of Cr loading catalysts was prepared by impregnation method. De-NOx activity and SO2 resistance of Cr doped catalysts were measured and the result shows that the introduction of Cr promotes both of them obviously. When the amount of loading Cr(calculate as Cr2O3) is 3%, the catalyst possesses the best low-temperature De-NOx activity and good N2 selectivity. Analysis of catalyst characterization shows that the main valence state of chromium in Cr doped catalyst is Cr3+. Cr enhances the oxidation of catalyst while increasing the amount of weak, strong acid site and surface active oxygen. The XPS result indicates that loading of Cr decreases the ratio of V5+/V4+ and leads a result of the free electrons formed in non-stoichiometric V. The In situ DRIFTs shows Cr loading facilitates the reaction of NO and NH3 absorbed on Brönsted acid site at low temperature and promote the NH3-selective catalytic reduction activity.

Key words: NH3-selective catalytic reduction, Cr doped catalyst, Low temperature De-NOx activity

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