还原热处理对铈锆铝复合氧化物性能的影响

Influence of Reductive Treatment on the Performance of CeO_2-ZrO_2-Al_2O_3 Composite Oxide

采用共沉淀法制备铈锆铝复合氧化物(CeO2-ZrO2-Al2O3,CZA)和铈锆复合氧化物(CeO2-ZrO2,CZ),将样品分别在空气和10%H2/Ar气氛下进行热处理,利用X射线粉末衍射(XRD)、O2脉冲吸附、H2程序升温还原(H2-TPR)等手段研究了复合氧化物的结构及性能.结果表明:CZA样品经950℃还原热处理后出现CeAlO3晶相,热处理温度越高,越有利于CeAlO3物相生成.CZA储氧量(OSC)随着还原热处理温度升高逐渐增大,至900℃达到1270.3μmo·lg-1;温度继续升高,OSC减小,1100℃还原热处理后CZA的OSC仅为23.2μmo·lg-1.研究发现还原热处理中形成CeAlO3,其显著影响CZA样品的储氧性能和还原性能.

A CeO2-ZrO2-Al2O3 composite oxide （CZA） and a CeO2-ZrO2 composite oxide （CZ） were prepared by the co-precipitation method.The samples were thermally aged in a flowing air atmosphere and in 10% H2/Ar flow.The structure and performance of the composite oxides were studied by X-ray diffraction （XRD）,oxygen storage capacity （OSC） measurements,and H2 temperature-programmed reduction （H2-TPR）.The results show that a CeAlO3 phase was formed after CZA was reductively aged at 950 ℃ and an increase in temperature benefited the formation of CeAlO3.The OSC of CZA increased with an increase in the reductive treatment temperature and it was 1270.3 μmol·g-1 when the temperature reached 900 ℃.However,the OSC decreased with an increase in the temperature.After CZA was reduced at 1100 ℃ the OSC was only 23.2 μmol·g-1.We found that the OSC and the reducibility of the material were remarkably influenced by the formation of a CeAlO3 phase after CZA was reductively aged.