Study on the properties and mechanisms for NOx storage over Pt/BaAl2O4-Al2O3 catalyst

被引：63

作者：

Li, XG

Meng, M ^{[1
]}

Lin, PY

Fu, YL

Hu, TD

Xie, YN

Zhang, J

机构：

[1] Univ Sci & Technol China, Dept Chem Phys, Hefei 230026, Peoples R China

[2] Chinese Acad Sci, Inst High Energy Phys, Beijing 100039, Peoples R China

来源：

TOPICS IN CATALYSIS | 2003年 / 22卷 / 1-2期

基金：

中国国家自然科学基金;

关键词：

Pt/BaAl2O4-Al2O3; NOx; storage; EXAFS; TPD; mechanism;

D O I：

10.1023/A:1021480115825

中图分类号：

O69 [应用化学];

学科分类号：

081704 ;

摘要：

The NOx storage catalyst Pt/BaAl2O4-Al2O3 was prepared by a coprecipitation-impregnation method. For fresh sample, the barium mainly exists as the BaAl2O4 phase except for some BaCO3 phase. The BaAl2O4 phase is the primary NOx storage phase of the sample. EXAFS and TPD were used for investigating the mechanism of NOx storage. It is found that two kinds of Pt sites are likely to operate. Site 1 is responsible for NO chemisorption and site 2 for oxidizing NO to nitrates and nitrites. When NO adsorbs on the sample below 200degreesC, it mainly chemisorbs in the form of molecular states. Such adsorption results in an increase of the coordination magnitude of Pt-O, and a decrease of that of Pt-Pt and Pt-Cl. The coordination distance of Pt-Pt, Pt-Cl and Pt-O also increases. When the adsorption occurs above 200degreesC, NO can be easily oxidized by O-2, and stored as nitrites or nitrates at the basic BaAl2O4. Site 2 is regenerated quickly. A high adsorption temperature is favorable for nitrate formation.

引用

页码：111 / 115

页数：5

共 17 条

[1] Use of IR and XANES to monitor catalysts during preparation, regeneration and reaction [J].