介孔酸性复合氧化物负载的稀燃氮氧化物储存还原催化剂研究

项目名称： 介孔酸性复合氧化物负载的稀燃氮氧化物储存还原催化剂研究

项目编号： No.20876110

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 孟明

作者单位： 天津大学

项目金额： 30万元

中文摘要： 由于Pt/Ba/Al2O3型NOx储存-还原(NSR)催化剂抗硫性能差，因此有必要研发新的催化剂。本项目采用酸性复合氧化物为载体，以碱金属K代替Ba作为储存剂，制备了多个系列的NSR催化剂。首先研发了负载型NSR催化剂Pt/K/TiO2-ZrO2，考察了载体焙烧温度、K负载量、储存剂种类和载体效应等对催化剂储存、抗硫和再生性能的影响，并对储存机制进行了探讨，结果表明，800oC焙烧时催化剂具有最大的NOx储存量，储存能力与载体的表面性能和K物种形态密切相关，NOx主要是硝酸盐以及少量亚硝酸盐物种储存，不同K物种形成的硝酸盐的稳定性为：K2CO3>氧化物>－OK基团，抗硫性能次序与此相反。助剂Co或Ce的加入能增强Pt/K/TiO2-ZrO2催化剂的氧化能力，从而显著提高其对NOx的储存能力，但抗硫性能略有下降。当在载体中添加Al2O3时NOx储存量和抗硫性能均明显提高，Al2O3的最佳掺杂量为Al/(Ti+Zr)原子比为3/1。此外，考察了TiO2-Al2O3-La2O3负载的NSR催化剂，发现掺杂少量La2O3能显著提高催化剂热稳定性，储存及抗硫性能，La2O3最佳掺杂量为3wt%。

中文关键词： 氮氧化物；储存还原；酸性复合载体；抗硫

英文摘要： Since Pt/Ba/Al2O3 NOx storage and reduction (NSR) catalysts show low sulfur-resisting ability,it is necessary to explore new kinds of NSR catalysts. In this project, acidic complex oxides were used as supports, and K was used as storage components to replace Ba,to prepare several series of NSR catalysts.At first,Pt/K/TiO2-ZrO2 catalysts were studied. The effects of support calcination temperature,K loading,kinds of storage components and supports on the performance for NOx storage and sulfur-resistance were systematically investigated,meanwhile,the NOx storage mechanism was also discussed.It is shown that the catalyst with the support calcined at 800oC showed the highest NOx storage capacity, which is highly determined by the surface property of support and states of K species. NOx is mainly stored as nitrates and nitrites species.The stability of nitrates formed from different K species shows the order as: K2CO3>oxides>-OK groups,however,the sulfur resistance shows totally different order.The addition of promoters Co or Ce to Pt/K/TiO2-ZrO2 increases its oxidation ability and NOx storage capacity, but the sulfur resistance is lowered to some extent. When Al2O3 is added to the support, both NOx storage and sulfur resistance performance of the catalysts are improved,the optimal atomic ratio of Al/(Ti+Zr) is 3/1.In addition,TiO2-Al2O3-La2O3 supported NSR catalysts were also investigated,and it is found that the presence of a small amount of La2O3 greatly increases the thermal stability,NOx storage capacity and sulfur resistance of the catalysts. The optimal doping amount of La2O3 is 3% by weight.

英文关键词： nitrogen oxides; storage and reduction; acidic complex oxides; sulfur resistance