【作者】 郑明丹；

【导师】 郭锡坤；

【作者基本信息】 汕头大学 ， 工业催化， 2009， 硕士

【摘要】 随着火力发电等工业的发展和机动车辆数量的增加,排放的氮氧化物(NOx,其中NO体积分数占90 %以上),一氧化碳,碳氢化合物日益增加;同时,随着全球能源危机的愈演愈烈,节能型贫燃发动机的设计和使用日趋发展。贫燃虽可提高燃料的燃烧效率,但也导致汽车尾气污染物,尤其是NOx排放量大幅度上升。汽车排放尾气中的CO、C3H6、NO既会造成严重的环境污染,也会直接危害人类的健康。因此,如何有效净化汽车尾气已成为国内外高度重视的问题。三效催化剂的研究一直是汽车尾气净化的主要途径,新型高效的非贵金属催化剂是近年来研究的热点。本文制备并研究了具有良好三效催化性能的新型非贵金属催化剂。①将AlNH4(SO4)2溶液缓慢滴入到NH4HCO3溶液和PEG6000的混合溶液中采用共沉淀法制备纳米氧化铝载体,等体积浸渍法浸渍助剂Ce4+、Zr4+、La3+和活性组分Cu2+,制备了催化剂Cu/Ce-Zr-La/γ-Al2O3;错误!未定义书签。②采用了溶胶凝胶法制备复合载体Ce/SnO2-TiO2,然后负载活性组分负载Cu2+,制成了催化剂Cu/Ce/ SnO2-TiO2(sol-gel)。通过活性测试分析催化性能,并采用扫描电子显微镜(SEM)、X-射线衍射(XRD)、热失重分析(TGA)、差热分析(DTA)等现代分析方法对催化剂结构进行表征,研究催化剂性能与结构的关系。对Cu/Ce-Zr-La/γ-Al2O3的研究结果表明,Cu/Ce-Zr-La/γ-Al2O3具有良好的三效催化性能,NO、CO和C3H6的起燃温度都较低,分别为250℃、150℃和300℃;CeO2-ZrO2对载体γ–Al2O3和活性组分Cu具有稳定作用,避免CuAl2O4尖晶石相的生成;La能够显著提高催化剂的热稳定性。对Cu/Ce/SnO2-TiO2(sol-gel)的研究结果表明, Ce4+可以有效提高催化剂的低温活性,与催化剂Cu/SnO2-TiO2相比,NO、CO和C3H6起燃温度分别降低了35℃、35℃和120℃,且NO、CO的最高转化率均达到90 %以上。表征结果显示,SnO2-TiO2主要以SnO2金红石结构为主,TiO2部分由锐钛矿结构变为具有较好还原活性的金红石结构,Ce4+的引入能明显细化催化剂颗粒,增强活性组分铜物种的分散度和催化剂的热稳定性,从而提高催化剂的三效催化性能。更多还原

【Abstract】 With the development of the thermal power generation technology and other industries as well as the increasing of the number of the automobile, the emission of nitrogen oxides, carbon monoxide and hydrocarbon is increasing. Meanwhile, as the aggravation of the global energy crisis, the designation and application of energy-saving engines in lean-burn condition has been developing. Although it can improve combustion efficiency of the fuels in lean-burn condition, it results in the largely increasing emission of vehicle exhausts, especially for NOx. Not only do NO, carbon monoxide and hydrocarbon cause series environmental pollution, but also they do harm to people’s health. Therefore, much attention is paid to the problem that how to effectively purify automobile exhaust both at home and abroad.Three-way-catalyst purification is the main method of the tail gas treatment, and the research on the new type catalyst with high efficiency non-noble metal, has become the top topic in recent years. Two kinds of non-noble metal catalysts with high efficiency catalytic activity have been studied in this thesis:①The Al2O3 support was prepared by the co-precipitation method with a AlNH4(SO4)2 aqueous solution dropping into a mixed NH4HCO3-PEG6000 aqueous solution. The Cu/Ce-Zr-La/γ-Al2O3 catalyst was obtained by impregnation of Al2O3 with promoter Ce4+, Zr4+, La3+ and active component Cu2+ aqueous solution.②The Ce/SnO2-TiO2(sol-gel) composite support was prepared by sol-gel method, and the Cu/Ce/SnO2-TiO2 catalyst was prepared by the impregnation of Ce/SnO2-TiO2 with active component Cu2+ aqueous solution. The catalysts were characterized by means of the X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TG).The investigation of the Cu/Ce-Zr-La/γ-Al2O3 catalyst indicated that the catalyst Cu/La/Ce-Zr/Al2O3 exhibited the high catalytic activity, and the conversion of NO could up to 100 % in the rang of 400℃and 800℃. The addition of the CeO2-ZrO2 , which formed the solid solution, greatly improved the catalytic activity, and the La promoter increased the thermal stability of the catalyst.The study of the relationship between the catalytic activity and the structure of the Cu/Ce/SnO2-TiO2(sol-gel) catalyst indicated that the addition of Ce4+ can significantly enhance the low temperature catalytic activity, and the light-off temperature of NO , CO and C3H6 were lowed by 35℃、35℃and 120℃, respectively, compared to the catalyst Cu/SnO2-TiO2 . The maximum conversion of NO and CO were both up to 90 %. The results of characterization indicate that the SnO2-TiO2 exists mainly as rutile structure, which has excellent reduction activity. The catalyst Cu/Ce/SnO2-TiO2(sol-gel) shows a high three way catalytic activity when the Ce4+ was loaded on, which could remarkable refine the particle size of catalyst, improve the dispersion degree of the active composition Cu and the thermal stability of catalyst.更多还原