DEVELOPMENT OF RARE EARTH BASED OXIDES FOR AUTOMOTIVE EXHAUST CATALYSTS

汽车尾气催化剂用稀土氧化物的开发

基本信息

批准号：
10555304
负责人：
ADACHI Gin-ya
金额：
$ 8.13万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10555304/
关键词：
Rare earth oxides Automotive exhaust catalysts Oxygen storage capacity Zirconia Rare earth oxalate Pyrochlore Hydrazine Chemical vapor transport 希土類シュウ塩酸マイクロエマルション微粒子逆ミセル

项目摘要

In this work we aimed development of rare-earth based oxides of high thermal stability and high catalytic activity. Especially we focused on ceria-zirconia mixed oxides which were applied as promoters in the automotive exhaust three-way catalysts.Nanosize Ceria and ceria-zirconia ultrafine particles prepared using a reaction within reversed micelles were characterized by HREM. The catalytic activities of the ceria-zirconia ultrafine particles supported on γ-alumina powders were higher than those given by the conventional catalysts prepared by the co-precipitation method, even after the heat treatment at 1273 K for 5 h in air.Ceria-zirconia solid solutions were also prepared by thermal decomposition of cerium zirconyl oxalate in an argon flow at 1273 K followed by oxidation at 673-873 K in air. The reduction behavior of the obtained powders was investigated and compared with the samples of high redox activity prepared by the conventional method. The ceria-zirconia samples prepared from the oxalate showed better reduction behavior, in spite of their very low surface areas. The reason for the behavior was attributed to both the appearance of a cubic phase with a different oxygen arrangement and the reduction by carbon formed in the sample preparation process.Surface modification of the ceria-zirconia solid solutions was carried out using formation and transport of volatile vapor complexes such as AlClィイD23ィエD2-CeClィイD23ィエD2 and AlClィイD23ィエD2-ZrClィイD24ィエD2, This process was named as "chemical filing." Reduction temperature of the sample after the chemical filing was lower than that of the fresh sample, and further decreased by a reduction/reoxidation cycle. The redox property of the chemically filed sample was maintained even after the redox cycles at high temperatures, indicating its durability compared to the solid solution prepared by a conventional procedure.

在这项工作中，我们旨在发展高热稳定性和高催化活性的稀土基氧化物。尤其是我们专注于二氧化碳混合氧化物，这些氧化物被用作汽车排气的三向催化剂中的启动子。纳米溶液和使用反向胶束中反应制备的ceria-zirconia Ultrafine颗粒以HREM为特征。即使在1273 K在1273 K的空气中进行热处理5小时，在γ-氧化铝粉末支撑的二氧化氧化颗粒的催化活性都高于传统催化剂的催化活性。还通过在1273 K处的氩气流中的氧化硫酸磷酸硫酸盐的热分解，然后在空气中为673-873 k氧化，制备了氧化剂。研究了获得的粉末的还原行为，并将其与传统方法制备的高氧化还原活性样品进行了比较。尽管表面积非常低，但从草酸盐制备的二氧化锌样品显示出更好的还原行为。 The reason for the behavior was attributed to both the appearance of a cubic phase with a different oxygen arrangement and the reduction by carbon formed in the sample preparation process.Surface modification of the ceria-zirconia solid solutions was carried out using formation and transport of volatile vapor complexes such as AlCl D23E D2-CeCl D23E D2 and AlCl D23E D2-ZrCl D24E D2, This process被称为“化学归档”。化学归档后样品的降低温度低于新鲜样品的温度，并通过还原/再氧化周期进一步降低。即使在高温下氧化还原周期后，也保持了化学归档样品的氧化还原特性，这表明其耐用性与传统程序制备的实心溶液相比。