催化学报 ›› 2016, Vol. 37 ›› Issue (11): 2018-2024.DOI: 10.1016/S1872-2067(16)62533-0

• 论文 • 上一篇    下一篇

贫燃条件In-Ag/TiO2-γ-Al2O3催化CO选择性还原NO

吴爽a,b, 李学兵c, 方向晨d, 孙媛媛c, 孙京b, 周明东b, 臧树良a,b   

  1. a 华东师范大学化学系, 上海 200062;
    b 辽宁石油化工大学化学与材料科学学院, 辽宁抚顺 113001;
    c 中国科学院青岛生物能源与过程研究所, 山东青岛 266101;
    d 中国石化抚顺石油化工研究院, 辽宁抚顺 113001
  • 收稿日期:2016-07-14 修回日期:2016-08-18 出版日期:2016-11-25 发布日期:2016-11-25
  • 通讯作者: Shuliang Zang,Tel:+86-24-56863837; E-mail:slzang@lnpu.edu.cn;Mingdong Zhou,Tel:+86-24-56860770; E-mail:mingdong.zhou@lnpu.edu.cn
  • 基金资助:

    国家科技支撑计划(2012BAF03B02);国家自然科学基金(21101085,U1162203);辽宁省自然科学基金(2015020196);山东省博士基金(BS2015HZ003);抚顺市科技厅(FSKJHT 201423);辽宁省高等学校优秀人才支持计划(LJQ2012031).

NO reduction by CO over TiO2-γ-Al2O3 supported In/Ag catalyst under lean burn conditions

Shuang Wua,b, Xuebing Lic, Xiangchen Fangd, Yuanyuan Sunc, Jing Sunb, Mingdong Zhoub, Shuliang Zanga,b   

  1. a Department of Chemistry, East China Normal University, Shanghai 200062, China;
    b School of Chemistry and Materials Science, Liaoning Shihua University, Fushun 113001, Liaoning, China;
    c Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, China;
    d Fushun Research Institute of Petroleum and Petrochemicals, Sinopec Group, Fushun 113001, Liaoning, China
  • Received:2016-07-14 Revised:2016-08-18 Online:2016-11-25 Published:2016-11-25
  • Contact: Shuliang Zang,Tel:+86-24-56863837; E-mail:slzang@lnpu.edu.cn;Mingdong Zhou,Tel:+86-24-56860770; E-mail:mingdong.zhou@lnpu.edu.cn
  • Supported by:

    This work was supported by the National Science & Technology Pillar Program (2012BAF03B02), National Natural Science Foundation of China (21101085, U1162203), Natural Science Foundation of Liaoning Province (2015020196), Doctoral Fund of Shandong Province (BS2015HZ003), Fushun Science & Technology Program (FSKJHT 201423), and Liaoning Excellent Talents Program in University (LJQ2012031).

摘要:

汽车尾气中主要污染成分CO和NOx可导致酸雨、光化学烟雾和臭氧空洞效应,对生物、环境及生态系统造成重大危害.污染源中CO是性能优良的还原剂,如能不添加还原剂实现CO催化还原NOx,将成为最具经济技术优势的NOx脱除技术.在富氧、低温条件下,利用CO选择性催化还原NOx为N2,是目前选择性催化还原研究中的热点和难点.催化CO还原NOx常用的贵金属Ir,Rh,Pt和Pd矿藏稀少,价格昂贵,有氧条件下活性急降,而分子筛催化剂和一些金属氧化物催化剂普遍存在反应温度高,尤其对N2选择性差等问题.
为解决上述问题,需寻找新的适合我国矿产资源的催化体系.研究发现,稀散金属基催化剂对氮氧化物的净化具有一定效果,因而可将我国的稀散金属资源优势转化为技术优势和经济优势.因此,本文以TiO2-γ-Al2O3(TA)为载体,In/Ag为活性组分,采用等体积浸渍法制备了InAg/TA以及In/TA,Ag/TA和InAg/Al(γ-Al2O3为载体)催化剂,考察了贫燃条件下CO选择性还原NO的催化活性.研究表明,双金属催化剂InAg/Al和InAg/TA的活性比单金属催化剂In/TA和Ag/TA高,In/TA催化剂中引入Ag物种能降低起燃温度;另外,相比于InAg/Al催化剂,InAg/TA催化剂具有较高的催化活性,550-600℃时N2产率超过60%,说明载体中引入TiO2可以提高催化剂活性.
为了深入研究InAg/TA催化剂中Ag物种和TiO2对In物种的作用,通过比表面测定、X射线衍射(XRD)、透射电子显微镜(TEM)、X射线光电子能谱、紫外-可见光吸收光谱、氢气程序升温还原、傅立叶变换红外线光谱等方法分析了催化剂结构和表面形态.结果表明,Ag物种可以提高In物种的分散性,In和Ag物种在TA载体表面可以很好地分散,从而有利于提高催化活性.In和Ag物种在TA载体表面以氧化态形式存在,并且Ag物种可以提高In物种表面含量,表面In和Ag物种含量越高,吸附活性位越多,催化活性越高;同时,TiO2也可以促进NO吸附,从而提高InAg/TA催化剂活性.
InAg/TA催化剂在450℃连续反应72 h进行稳定性测试,测试前后分别在50-600℃进行活性测试,并用XRD和TEM对反应后的催化剂进行表征测试.结果表明,InAg/TA催化剂具有较好的稳定性,连续反应前后催化剂活性基本保持不变,推测可能由于在有CO和O2存在的体系中,Ag物种利用自身Ag+与Ag0之间的氧化还原反应抑制了活性组分In2O3的还原和聚集,稳定了In物种乃至催化剂活性.
InAg/TA催化剂用于贫燃条件下CO还原NO具有较好的催化效果,主要归因于催化剂活性组分分散性好,稳定性高,对NO吸附能力强.Ag物种可以稳定In物种并提高其分散性,TiO2可以改善In物种和Ag物种的分散性并促进NO吸附.

关键词: 一氧化碳还原一氧化氮, 贫燃, 铟/银双金属催化剂, 脱硝

Abstract:

TiO2/γ-Al2O3 supported In/Ag catalysts were prepared by impregnation method, and investigated for NO reduction with CO as the reducing agent under lean burn conditions. The microscopic struc-ture and surface properties of the catalysts were studied by N2 adsorption-desorption, X-ray diffrac-tion, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spec-troscopy, H2 temperature-programmed reduction and Fourier transform infrared spectroscopy. TiO2/γ-Al2O3 supported In/Ag is a good catalyst for the reduction of NO to N2. It displayed high dis-persion, large amounts of surface active components and high NO adsorption capacity, which gave good catalytic performance and stability for the reduction of NO with CO under lean burn condi-tions. The silver species stabilized and improved the dispersion of the indium species. The introduc-tion of TiO2 into the γ-Al2O3 support promoted NO adsorption and improved the dispersion of the indium species and silver species.

Key words: Nitrogen oxide reduction with carbon monoxide, Lean burn condition, Indium/silver bimetallic catalyst, Removal of nitrogen oxides