沉淀陈化对Ce0.7Mn0.3Ox催化净化柴油车尾气碳颗粒的影响  

Effects of precipitation ripening on the catalytic diesel soot purification of Ce0.7Mn0.3Ox mixed oxides

作　　者：罗利萍 唐林茜 周子众 杨艳 黎云祥 任丽平 曾超 张纳 杨铮铮 LUO Liping;TANG Linxi;ZHOU Zizhong;YANG Yan;LI Yunxiang;REN Liping;ZENG Chao;ZHANG Na;YANG Zhengzheng(College of Environmental Science and Engineering,China West Normal University,Nanchong 637009,Sichuan,China;Department of Science and Innovation,Nanchong Senior High School,Nanchong 637009,Sichuan,China)

机构地区：[1]西华师范大学环境科学与工程学院,南充637009 [2]南充高中科技创新部,南充637009

出　　处：《环境化学》2019年第10期2283-2293,共11页Environmental Chemistry

基　　金：国家自然科学基金(21703174);西华师范大学英才基金(17YC146,17YC145);西华师范大学博士启动基金(15E012);西华师范大学教学改革与研究项目(jgxmyb18203);四川省大学生创新创业训练项目(201810638092)资助~~

摘　　要：采用沉淀陈化法制备了Ce∶Mn摩尔比为7∶3的CeO2-MnOx复合氧化物(Ce0.7Mn0.3Ox-PR),并使用X射线多晶粉末衍射(XRD)、场发射扫描电子显微镜(SEM)、高分辨率透射电子显微镜(TEM)、N2吸附-脱附、X射线光电子能谱(XPS)和拉曼光谱(Raman)对所制备复合氧化物催化剂进行表征.结果表明,沉淀陈化过程可有效促进Ce0.7Mn0.3Ox-PR催化剂晶粒的生长,稳定催化剂的织构性质,且明显有利于Mn离子进入CeO2晶格,减少MnOx物种在催化剂表面的聚集.Mn离子进入CeO2晶格可有效增加Ce0.7Mn0.3Ox-PR催化剂的晶格氧和氧空位,从而有助于其表现出更优异的碳颗粒催化氧化性能.所制备的Ce0.7Mn0.3Ox-PR催化剂对碳颗粒催化氧化的起燃温度(T50)为362℃、完全转化温度(T90)为419℃,该性能明显优于传统共沉淀法所制备的Ce0.7Mn0.3Ox-CP催化剂的性能(T50、T90分别为376℃、457℃).CeO2-MnOx mixed oxides with a molar ratio of Ce∶Mn=7∶3 were prepared by precipitation ripening method,and labeled as Ce0.7Mn0.3Ox-PR.The catalytic soot oxidation activity of prepared Ce0.7Mn0.3Ox-PR was compared with the traditional commercial Ce0.7Mn0.3Ox soot oxidation catalyst(prepared by co-precipitation method,labeled as Ce0.7Mn0.3Ox-CP).Meanwhile,the catalysts were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),N2 adsorption-desorption,X-ray photoelectron spectroscopy(XPS)and Raman spectra.Results displayed that the precipitation ripening could efficiently promote the growth of crystalline grain and stabilize the textual features of catalyst.For the Mn species,the precipitation ripening was beneficial for the generating of Mn^4+,which was a promoting factor for the oxygen mobility of CeO2;furthermore,the precipitation ripening was favorable for Mn ions to enter into the CeO2 lattice and retarding the agglomeration of MnOx species over catalyst surface.Mn ions into CeO2 lattice were able to significantly enhance the amounts of lattice oxygen and oxygen vacancies of Ce0.7Mn0.3Ox-PR catalyst,and hence improving the catalytic soot oxidation activity of Ce0.7Mn0.3Ox-PR catalyst.Since lattice oxygen and oxygen vacancies were beneficial for the formation of active oxygen.Finally the catalytic activity tests showed that the light-off temperature(T50)and complete conversion temperature(T90)for soot oxidation of Ce0.7Mn0.3Ox-PR was about 362℃ and 419℃,respectively;which are obviously better than the traditional Ce0.7Mn0.3Ox-CP catalyst(T50 and T90 are 376℃ and 457℃,respectively).

关 键 词：汽车尾气净化 碳颗粒催化净化 CeO2-MnOx 催化剂 沉淀陈化 

分 类 号：O64[理学—物理化学]