SCR脱硝催化剂对烟气中零价汞的氧化效率研究

李建荣; 何炽; 商雪松; 陈进生; 喻小伟; 姚沅君

SCR脱硝催化剂对烟气中零价汞的氧化效率研究

1.
中国科学院城市环境研究所城市环境与健康重点实验室, 福建厦门 361021;
2.
中国科学院研究生院, 北京 100049

基金项目: 福建省面上基金项目(2011J01060); 中国科学院知识创新工程重要方向项目(KZCX2-YW-JS404)。

详细信息

通讯作者:
陈进生, Tel: 0592-6190765, E-mail: jschen@iue.ac.cn。

中图分类号: X51
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出版历程
- 收稿日期: 2011-08-31
- 修回日期: 2011-11-28
- 刊出日期: 2012-02-29

Oxidation efficiency of elemental mercury in flue gas by SCR De-NO_x catalysts

1.
Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China;
2.
Graduate University of Chinese Academy of Sciences, Beijing 100049, China

摘要

摘要: 采用模拟实验方法,在氧化气氛工况和SCR(选择性催化还原法)工况下,对比研究新鲜的和运行40 000 h的SCR催化剂对零价汞(Hg⁰)的氧化效率,并结合N₂吸/脱附、SEM-EDS、FT-IR、离子色谱法等手段对催化剂的组成及结构进行了表征。结果表明,在氧化气氛工况下(一定的HCl和O₂浓度),40 000 h催化剂对零价汞的氧化效率比新鲜催化剂低5%~20%,但是,在SCR工况(氧化气氛下加入NH₃和NO)下,氧化效率仅下降5%~10%。运行40 000 h催化剂出现表面颗粒的团聚现像,而且比表面积、活性物质V及V⁵⁺=O基团的含量均相对下降;然而,运行40 000 h催化剂的水溶性离子含量(特别是Na⁺、K⁺、NH₄⁺、SO₄^2-)要高于新鲜催化剂。这些因素都会影响催化剂表面活性位和内部孔道结构,从而影响到催化剂对于烟气中Hg⁰的氧化效率。
- SCR /
- 脱硝催化剂 /
- 烟气 /
- 零价汞 /
- 氧化效率
Abstract: The oxidation efficiency of elemental mercury (Hg⁰) by fresh and 40 000 h SCR (Selective Catalytic Reduction) catalysts was studied with the help of simulated experiments under oxidation and SCR conditions, respectively. The structural and textural properties of the catalysts were characterized by various techniques, including N₂ adsorption/desorption, SEM-EDS, FT-IR, and ion chromatography. It was found that the Hg⁰ oxidation efficiency over the 40 000 h catalyst is about 5%~20% lower than that of the fresh one under the oxidation condition (with HCl and O₂), whereas it just decreases by about 5%~10% under the SCR condition (when NH₃ and NO are added). The particles agglomeration phenomenon was observed for the 40 000 h catalyst, of which the BET, V content, and V⁵⁺ = O quantity decrease to some extent. The contents of the water-soluble ions (such as Na⁺, K⁺, NH₄⁺, and SO₄^2-) of the 40 000 h catalyst are higher than those of the fresh one. All these factors have a negative influence on the pore structure and active sites distribution over the 40 000 h catalyst, thereby reducing its Hg⁰ oxidation efficiency.
- SCR /
- de-NO_x catalyst /
- flue gas /
- elemental mercury /
- oxidation efficiency

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