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Mechanism of NOx storage in ceria containing storage reduction catalyst materials

含二氧化铈存储还原催化剂材料的NOx存储机理

基本信息

批准号：
189155687
负责人：
Professor Dr. Christian Hess
金额：
--
依托单位：
Fachgebiet Physikalische Chemie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2010
资助国家：
德国
起止时间：
2009-12-31 至 2016-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/189155687?language=en
关键词：
Mechanism NOx storage ceria containing

项目摘要

Despite the success of the first generation of NOx storage reduction catalysts (Pt/BaO/Al2O3) further developments of NOx storage reduction catalyst technology are urgently needed to improve the efficiency and durability as well as to meet future NOx emission standards. These include the development of more efficient storage and support materials countering a reduction in long term stability by thermal degradation and sulfur poisoning. As described in the literature, the presence of ceria in NOx storage reduction catalysts (Pt/BaO/CeO2/Al2O3) leads to an increase in NOx storage capacity at temperatures up to 300°C as well as to improved stability. However, a fundamental understanding of the mode of operation of such ceria containing NOx storage reduction catalysts is still missing. Thus the goal of this project is to elucidate the influence of ceria on the NOx storage mechanism and the properties of the storage component at temperatures up to 300°C using barium oxide/ceria mixed systems.Barium oxide/ceria mixed systems will first be investigated without and then with support (Al2O3) and nobel metal (Pt) component. To elucidate the NOx storage mechanism for the different ceria containing materials, the in situ Raman/FTIR methodology developed in the first founding period will be employed. This approach combines the potential of in situ Raman spectroscopy with quantitative FTIR gas phase analysis at the outlet of the in situ Raman cell. These studies include the determination of the corresponding NOx storage capacities. Due to the complexity of ceria containing NOx storage reduction catalysts the in situ Raman characterization will be supported by detailed studies using X-ray photoelectron spectroscopy (XPS) partly in combination with Raman and und UV-Vis spectroscopy.As the stability of NOx storage reduction catalysts is strongly related to their susceptibility to sulfur poisoning one focus of the project is to investigate the influence of sulfur (as SO2). Besides, the influence of other components with large volume fractions in the exhaust gas (CO2, H2O) will be studied. Their presence may significantly influence the NOx storage mechanism as demonstrated for H2O during the first funding period.

尽管第一代NOx储存还原催化剂(Pt/BaO/Al_2O_3)取得了成功，但迫切需要进一步开发NOx储存还原催化剂技术，以提高催化剂的效率和耐久性，并满足未来的NOx排放标准。这些措施包括开发更有效的储存和支持材料，以应对因热降解和硫磺中毒而导致的长期稳定性下降。如文献所述，在NOx储存还原催化剂(Pt/BaO/CeO2/Al_2O_3)中加入CeO_2后，NOx在300°C以下的储存容量增加，稳定性也得到改善。然而，对这种含CeO2的NOx储存还原催化剂的操作模式仍然缺乏基本的了解。因此，本项目的目标是利用BaO_2O_3/CeO_2混合体系来阐明CeO_2对NOx存储机理的影响以及在300°C温度下存储组件的性质。首先将研究BaO_2O_3/CeO_2混合体系，然后在没有载体(Al_2O_3)和贵金属(P_T)的情况下进行研究。为了阐明不同含CeO2材料的NOx存储机理，将采用在第一个创建阶段发展起来的原位拉曼/FTIR方法。这种方法结合了原位拉曼光谱的潜力和原位拉曼池出口处的定量FTIR气相分析。这些研究包括确定相应的NOx存储容量。由于含CeO2的NOx储存还原催化剂的复杂性，利用X射线光电子能谱(XPS)的详细研究将部分结合拉曼光谱和紫外可见光谱来支持原位拉曼表征。由于NOx储存还原催化剂的稳定性与其对硫中毒的敏感性密切相关，因此本项目的重点之一是考察硫(作为SO2)的影响。此外，还研究了尾气中体积分数较大的其他组分(CO2、H2O)的影响。它们的存在可能会对NOx储存机制产生重大影响，正如在第一个供资期间对H2O所显示的那样。