Comparative study of structural properties and NOx storage-reduction behavior of Pt/Ba/CeO2 and Pt/Ba/Al2O3

被引：37

作者：

Casapu, A. ^{[1
]}

Grunwaldt, J. -D. ^{[1
]}

Maciejewski, M. ^{[1
]}

Krumeich, F. ^{[1
]}

Baiker, A. ^{[1
]}

Wittrock, M. ^{[2
]}

Eckhoff, S. ^{[2
]}

机构：

[1] ETH, Inst Chem & Bioengn, Dept Chem & Appl Biosci, CH-8093 Zurich, Switzerland

[2] Umicore AG & Co KG, D-63403 Hanau, Germany

来源：

APPLIED CATALYSIS B-ENVIRONMENTAL | 2008年 / 78卷 / 3-4期

关键词：

NOx storage-reduction catalyst; ceria; pre-treatment; thermal analysis; X-ray absorption spectroscopy;

D O I：

10.1016/j.apcatb.2007.09.030

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Differences in the NOx storage-reduction (NSR) behavior of Pt/Ba/CeO2 and Pt/Ba/Al2O3 have been identified and traced to their different chemical and structural properties. The results show that Pt/Ba/CeO2 exhibits inferior NO, storage and, particularly, reduction (regeneration) activity compared to the Al2O3 supported catalyst. The incomplete reduction of the stored NOx-species in Pt/Ba/CeO2 seems to be caused by a faster and more profound reoxidation of Pt particles during the lean period as evidenced by in situ X-ray absorption spectroscopy. Interestingly, the reduction activity could be significantly improved by a pre-reduction step at mild conditions. Exposure of the Pt/Ba/CeO2 catalyst to reducing H-2 atmosphere in the temperature range 300-500 degrees C lead to a moderate increase of Pt particle size which beneficially influenced the regeneration activity. In contrast, pre-reduction at temperatures above 500 degrees C was unfavorable and resulted in a severe decrease of the regeneration activity, probably due to migration of the partially reduced CeO2 onto the surface of Pt particles. (c) 2007 Elsevier B.V. All rights reserved.

引用

页码：288 / 300

页数：13

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