催化学报 ›› 2020, Vol. 41 ›› Issue (5): 877-888.DOI: 10.1016/S1872-2067(20)63532-X

• 论文 • 上一篇    下一篇

Cu2+离子掺杂SnO2固溶体催化剂的晶格容量效应:NH3选择性还原NOx反应性能提高的本质原因

徐香兰a, 佟云艳a, 张景岩a, 方修忠a, 徐骏伟a, 刘福燕a, 刘建军b, 钟伟c, Olga E. Lebedevad, 王翔a   

  1. a 南昌大学化学学院, 江西省环境与能源催化重点实验室, 江西南昌 330031, 中国;
    b 江西宝安新材料科技有限公司, 江西萍乡 337000, 中国;
    c 嘉兴学院生物与化学工程学院, 浙江嘉兴 314001, 中国;
    d 贝尔哥罗德国家研究大学, 贝尔哥罗德, 俄罗斯
  • 收稿日期:2019-11-13 修回日期:2019-12-10 出版日期:2020-05-18 发布日期:2019-12-31
  • 通讯作者: 王翔
  • 基金资助:
    国家自然科学基金(21567016,21666020,21962009);江西省自然科学基金(20181ACB20005,20171BAB213013);江西省环境与能源催化重点实验室(20181BCD40004);国家重点研发计划(2016YFC0209302);江西省研究生创新基金(YC2018-B015);浙江省自然科学基金(LY18B010007).

Investigation of lattice capacity effect on Cu2+-doped SnO2 solid solution catalysts to promote reaction performance toward NOx-SCR with NH3

Xianglan Xua, Yunyan Tonga, Jingyan Zhanga, Xiuzhong Fanga, Junwei Xua, Fuyan Liua, Jianjun Liub, Wei Zhongc, Olga E. Lebedevad, Xiang Wanga   

  1. a Key Laboratory of Jiangxi Province for Environment and Energy Catalysis, College of Chemistry, Nanchang University, Nanchang 330031, Jiangxi, China;
    b Jiangxi Baoan New Material Technology Corporation, LTD, Pingxiang 337000, Jiangxi, China;
    c College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, Zhejiang, China;
    d Belgorod State National Research University, Pobeda Str., 85 Belgorod, 308015, Russian Federation
  • Received:2019-11-13 Revised:2019-12-10 Online:2020-05-18 Published:2019-12-31
  • Contact: 10.1016/S1872-2067(20)63532-X
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (21567016, 21666020, 21962009), the Natural Science Foundation of Jiangxi Province (20181ACB20005, 20171BAB213013), the Key Laboratory Foundation of Jiangxi Province for Environment and Energy Catalysis (20181BCD40004), National Key Research and Development Program of China (2016YFC0209302), the Innovation Fund Designated for Graduate Students of Jiangxi Province (YC2018-B015) and Natural Science Foundation of Zhejiang Province (LY18B010007),

摘要: NOx排放给人类健康和环境带来了严重的危害,目前已发展了多种消除其污染的方法.其中氨选择性催化还原(NH3-SCR)技术是固定源和移动源柴油机排放NOx的有效消除方法之一.非贵金属氧化物催化剂由于廉价、且原料来源丰富,用于NH3-SCR反应在过去几十年一直备受人们关注.由于晶格畸变和不等价取代等原因,与单组分氧化物催化剂相比,替代型金属氧化物固溶体催化剂通常具有更优异的物理化学性能.其中典型的例子是已被广泛用作汽车尾气净化转化器储氧材料的铈锆固溶体.与纯CeO2相比,Zr4+离子溶入立方萤石CeO2晶格形成固溶体结构后,显著提高了其稳定性和储氧能力.近八年来,我们以四方金红石型SnO2为溶剂,系统地研究了系列金属阳离子在其晶格中的溶解行为,并考察了其催化反应性能.为深入理解固溶体催化剂的结构与反应性能之间的关系,我们首次创建了简单易行的XRD外推法定量金属氧化物固溶体中溶质阳离子的晶格容量.结果表明,其它离子掺杂形成SnO2基固溶体可显著增加其表面缺位氧和Lewis酸性位点的数量,且可使缺位氧在较高温度下保持稳定,显著提高了所得催化剂的反应性能.另外我们还发现,当溶质离子含量为晶格容量时可得到最大量的纯相固溶体,此时催化剂通常具有最优的性能,具有明显的阈值效应.
很多研究表明,含CuO的一些催化材料通常对NOx选择还原具有良好的低温活性和选择性,但把Cu2+离子溶入SnO2晶格构建固溶体催化剂用于NH3-SCR反应迄今未见报道.因此,为获得性能优良的催化剂,本文采用共沉淀法制备了系列不同Cu2+离子含量的Sn-Cu复合氧化物固溶体催化剂,并采用XRD外推法测定了Cu2+离子在SnO2中的晶格容量,为0.10g CuO/g SnO2,相当于Sn/Cu摩尔比为84/16.Raman结果表明,Cu2+离子含量低于晶格容量时,随其含量增加,表面氧缺位数量增加,且在晶格容量时达到最大.H2-TPR,O2-TPD和NH3-TPD结果表明,随着Cu2+离子含量增加,催化剂表面活性氧物种和表面酸中心的数量均增加;在Cu2+离子含量接近晶格容量时,催化剂中形成最大量的纯固溶体相,上述活性中心均可达到最大量.此时,催化剂具有最佳的NH3-SCR反应性能.因此,Cu2+离子溶入SnO2晶格形成固溶体催化剂,在结构和反应性能上均具有明显的晶格容量阈值效应.通过将Cu2+离子含量调控在晶格容量,可获得反应性能最好的Sn-Cu复合氧化物固溶体催化剂.

关键词: SnO2基固溶体, Cu2+离子晶格容量, XRD外推法, NOx的NH3选择还原, 晶格容量阈值效应

Abstract: To understand the effect of the doping amount of Cu2+ on the structure and reactivity of SnO2 in NOx-SCR with NH3, a series of Sn-Cu-O binary oxide catalysts with different Sn/Cu ratios have been prepared and thoroughly characterized. Using the XRD extrapolation method, the SnO2 lattice capacity for Cu2+ cations is determined at 0.10 g CuO per g of SnO2, equaling a Sn/Cu molar ratio of 84/16. Therefore, in a tetragonal rutile SnO2 lattice, only a maximum of 16% of the Sn4+ cations can be replaced by Cu2+ to form a stable solid solution structure. If the Cu content is higher, CuO will form on the catalyst surface, which has a negative effect on the reaction performance. For samples in a pure solid solution phase, the number of surface defects increase with increasing Cu content until it reaches the lattice capacity, as confirmed by Raman spectroscopy. As a result, the amounts of both active oxygen species and acidic sites on the surface, which critically determine the reaction performance, also increase and reach the maximum level for the catalyst with a Cu content close to the lattice capacity. A distinct lattice capacity threshold effect on the structure and reactivity of Sn-Cu binary oxide catalysts has been observed. A Sn-Cu catalyst with the best reaction performance can be obtained by doping the SnO2 matrix with the lattice capacity amount of Cu2+.

Key words: SnO2-based solid solution, Lattice capacity of Cu2+, XRD extrapolation method, NOx-SCR with NH3, Threshold effect