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Ag Cluster Catalyst-Research of Reaction Mechanism and Development of Diesel deNOx Catalyst

银簇催化剂-反应机理研究及柴油脱硝催化剂开发

基本信息

批准号：
17360386
负责人：
SATSUMA Atsushi
金额：
$ 9.53万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17360386/
关键词：
Silver Cluster Selective Reduction of NOx Diesel engines in-situ Spectroscopy DFT calculation Active oxygen Reaction mechanism ディーゼル耐SOx性

项目摘要

Reduction of NOx from diesel engine cars is serious problem from environmental points of view. We have found that Ag duster having the Size of nano to sub-nano scale is very effective for the selective reduction of NOx by unburned hydrocarbons RIC-SCR) in the excess of oxygen. The aim of this project is to reveal the dynamics and the reaction mechanism of HC-SCR over Ag duster by using in-situ spectroscopy and DET calculations in order to guide the design of practical catalysts. The following results have been obtained in the term of the project.1.Reactivity and reaction mechanism of Ag duster : It was hind by ESR spectrometer that the contact of gaseous oxygen and Ag duster formed by a slight reduction of Ag-alumina by hydrogen results in the formation of super-oxide species. The important role of Ag duster on the activation of oxygen was clarified. Furthermore, the role of hydrogen on the activation of oxygen and the formation of Ag cluster was suggested.2. Evaluation of reaction mechanism by DFP calculation: Formation of Ag duster by hydrogen and activation of oxygen on its surface was evaluated by DFP calculation. Ag 4-membered cluster (Ag_4^<2+>) is the most stable in zeolite cage, which is in harmony with the experimental results by EKAFS. The contact of hydrogenated Ag duster (H-H-Ag_4^<2+>) with oxygen results in the formation of hydrogen peroxide. The experimental results can be rationalized by this model, because the hydrogen peroxide is active for both oxidation of hydrocarbons ns to oxygenated species and NO to NO23. SOx tolerance of Ag duster in the presence of hydrogen: High SOx tolerance of Ag duster was achieved through optimization of the kind of reductants, temperature, and co-feeding of hydrogen. The high SIX tolerance is caused by migration of SOx from Ag surface to gas phase or alumina support.

从环境观点来看，减少柴油机汽车中的NOx是一个严重的问题。我们已经发现，具有纳米至亚纳米尺度尺寸的Ag除尘器对于在过量氧气下通过未燃烧的烃RIC-SCR）选择性还原NOx是非常有效的。本课题的目的是通过原位光谱和DET计算，揭示银催化剂上HC-SCR反应的动力学和反应机理，以指导实际催化剂的设计。1. Ag粉的反应性及反应机理：ESR谱表明，Ag粉与氢气轻微还原形成的Ag粉接触，形成超氧化物物种。阐明了银粉在活化氧中的重要作用。此外，还研究了氢对氧的活化和Ag团簇形成的影响.通过DFP计算评价反应机理：通过DFP计算评价由氢气和其表面上的氧的活化形成Ag粉尘。Ag四元团簇（Ag_4^<2+>）在沸石笼中最稳定，这与EKAFS的实验结果一致。氢化Ag粉（H-H-Ag_4^<2+>）与氧气接触，生成过氧化氢。实验结果可以通过该模型合理化，因为过氧化氢对于烃ns氧化成含氧物种和NO氧化成NO23都是活性的。在氢气存在下的Ag除尘器的SOx耐受性：通过优化还原剂的种类、温度和氢气的共进料来实现Ag除尘器的高SOx耐受性。高的SIX耐受性是由于SOx从Ag表面迁移到气相或氧化铝载体引起的。