掺杂Mn对CeO_2-ZrO_2-Al_2O_3材料性质的影响  

Effects of Doping Manganese on the Properties of CeO_2-ZrO_2-Al_2O_3

作　　者：潘依浪[1] 温怡芸[1] 陈耀强[1] 龚茂初[1] 

机构地区：[1]四川大学化学学院绿色化学与技术教育部重点实验室,成都610064

出　　处：《高等学校化学学报》2009年第2期337-343,共7页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:20773090);国家"八六三"计划(批准号:2006AA06Z347);教育部博士点基金(批准号:20070610026)资助

摘　　要：采用共沉淀法制备了一系列Mn掺杂摩尔分数为0～5%的CeO2-ZrO2-Al2O3(CZA)复合氧化物,并采用BET,OSC,XRD,XPS,H2-TPR等方法对所制备的材料进行了表征.结果表明,所制备的材料均形成了稳定的CZA固溶体,尤其是Mn掺杂0.5%的材料在600和1000℃焙烧后均表现出最好的织构性能.OSC和H2-TPR的结果表明,Mn掺杂量≤1%时,氧在材料中的体相移动是材料储氧和被还原的速控步骤,并且Mn的掺杂量为0.2%时,储氧量最大,材料的还原温度也最低;Mn掺杂量>1%时,Mn物种对材料储氧和被还原的作用显著.XPS结果表明,Mn在焙烧过程中会迁移向表面,结合H2-TPR结果可知,新鲜样品表面的MnOx物种主要为Mn2O3,而老化样品主要为Mn3O4.A series of oxygen-storage materials CeO2-ZrO2-Al2O3 （CZA） with Mn dopant from 0 to 5% （ molar fraction） were prepared by the co-precipitation method and characterized by specific surface area measurements （ BET）, oxygen storage capacity （ OSC ）, X-ray diffraction （ XRD）, H2-temperature-programmed reduction（H2-TPR）, and X-ray photoelectron spectroscopy （XPS）. The results show that these successfully-prepared CZA solid solutions have an optimum textural performance with a dopant ratio of 0. 5% before and after calcining at 1000℃ for 5 h. According to the OSC and the H2-TPR, the oxygen bulk diffusion was the ratecontrolled step of oxygen storage and redox when molar fraction of Mn was less than 2%, however, the material with 0. 2% Mn displayed optimum performances such as the lagerest OSC and the lowest reduction temperature. The OSC and the redox properties were mainly depended by Mn species when molar fraction of Mn was more than 2%. XPS results show that Mn is transferred from the bulk to the surface of materials by calcination. Moreover, the H2-TPR show that the MnOx species on the surface of the fresh samples are mainly consisted of Mn2O3 whereas these on the surface of the aged samples mostly are made up of Mn3O4.

关 键 词：CeO2-ZrO2-Al2O3 MNOX 储氧量 还原性能 

分 类 号：O643[理学—物理化学]