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Preparation of sizes controlled supported metal catalysts and investigation of their thermal stability and catalytic performances

尺寸可控负载型金属催化剂的制备及其热稳定性和催化性能研究

基本信息

批准号：
10555279
负责人：
WAKABAYASHI Katsuhiro
金额：
$ 0.96万
依托单位：
KYUSHU 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

项目摘要

In this work we have succeeded in preparing Pt-size controlled Pt/AlィイD22ィエD2OィイD23ィエD2 catalysts by a novel preparation method using microemulsion. When Pt-complex nanoparticles in microemulsion were used in the preparation, the Pt particle size of the catalyst varied with the precursor type in microemulsion. The size of the Pt particles of the prepared Pt/AlィイD22ィエD2OィイD23ィエD2 catalysts could be controlled in range of 3.8-23.4 nm by changing the length of alkyl group in the complex-forming agents.The catalytic performances in NO-CO reaction over those Pt-size controlled catalysts thus prepared were investigated and compared with the catalytic performance of the Pt/AlィイD22ィエD2OィイD23ィエD2 catalysts prepared by the conventional impregnation method. It was found that the catalysts prepared using microemulsion exhibited a higher activity for NO reduction by CO than the one prepared by the impregnation method.The thermal stability of platinum particles of Pt/AlィイD22ィエD2OィイD23ィエD2 catalysts against sintering was examined heating the catalysts at 700℃ under air flow for 12 h. The platinum particles of the catalysts prepared by this method were considered to be difficult to sinter, because the particles were partly embedded in the alumina. However, the particle size became larger due to sintering. It was considered that the platinum particles in the catalysts could move easily because of the large pore size of alumina support. In order to avoid aggregation of the particles, the pore size was decreased by pressing the catalysts. The catalyst thus pressed exhibited extremely high thermal stability compared with the catalysts before pressing.

在本工作中，我们成功地用一种新的微乳液制备方法制备了铂尺寸可控的铂/AlィイD22ィエD2OィイD23ィエD2催化剂。当使用微乳液中的铂复合纳米颗粒制备催化剂时，催化剂的铂颗粒大小随微乳液中前驱体类型的不同而不同。通过改变络合剂中烷基团的长度，可以将所制备的Pt/AlィイD22ィエD2OィイD23ィエD2催化剂的铂颗粒尺寸控制在3.8~2 3.4 nm范围内，考察了所制备的催化剂在NO-CO反应中的催化性能，并与传统浸渍法制备的催化剂进行了比较.结果表明，与浸渍法制备的催化剂相比，微乳液法制备的催化剂对CO还原NO具有更高的催化活性。在700℃的空气中加热12h，考察了铂颗粒对催化剂抗烧结性的影响，认为浸渍法制备的催化剂中存在部分铂颗粒，难以烧结。然而，由于烧结，颗粒尺寸变大。认为由于氧化铝载体的孔径较大，催化剂中的铂颗粒容易移动。为了避免颗粒的团聚，通过对催化剂的压制减小了孔径。与压制前的催化剂相比，压制后的催化剂具有极高的热稳定性。