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.

从环境角度来看，减少柴油发动机汽车的氮氧化物是一个严重的问题。我们发现，纳米至亚纳米级尺寸的银喷粉对于在过量氧气中通过未燃烧的碳氢化合物（RIC-SCR）选择性还原NOx非常有效。该项目的目的是通过原位光谱和DET计算揭示Ag除尘器上HC-SCR的动力学和反应机理，以指导实际催化剂的设计。项目期间取得了以下成果： 1.银粉的反应活性及反应机理：经ESR光谱仪分析，银粉被氢气轻微还原而形成气态氧与银粉接触的结果。超氧化物的形成。阐明了银粉对氧气活化的重要作用。进一步提出了氢对氧的活化和银团簇形成的影响。 2．通过DFP计算评估反应机理：通过DFP计算评估氢气形成银粉以及其表面氧的活化。 Ag 4元团簇(Ag_4^<2+>)是沸石笼中最稳定的，这与EKAFS的实验结果一致。氢化银粉(H-H-Ag_4^2+)与氧的接触导致过氧化氢的形成。实验结果可以通过该模型合理化，因为过氧化氢对于将碳氢化合物氧化成含氧物质和将NO氧化成NO23都具有活性。氢气存在下银粉除尘器的 SOx 耐受性：通过优化还原剂种类、温度和氢气共进料，实现了银除尘器的高 SOx 耐受性。高 SIX 耐受性是由 SOx 从银表面迁移到气相或氧化铝载体造成的。