锰基SCR脱硝催化剂的价态调控及其低温催化机理研究

Mn-based catalyst is considered as one of the most promising catalysts for the abatement of NOx emission from stationary sources because of its high efficiency, selectivity, and economy. MnOx contain various types of labile oxygen and pxidation states of manganese, possess several stable species with different Mn valence, which has significant influence on the surface atomic transition and catalytic reaction process. It is necessary to indentify the MnOx species and Mn valence and reveal the low temperature NH3-SCR mechanism. However, less attention has been paid to a systemtic research of the relationship between MnOx species and the catalytic mechanism in the previous studies. In this project, the catalytic reaction mechanism of pure MnOx and hybrid MnOx with different valence state will be systematically studied. Furthermore, the preparation of Mn-based catalysts was usually carried out by coprecipitation method, sol-gel route, or impregnation process, which needs complicated manipulation and always brings about a low catalytic activity. The rheological phase method exhibits such distinctive advantages as low cost, easy manipulation, and rapid reaction compared with conventional methods. During the initial research period, several MnOx/TiO2 catalysts were successfully synthesized by this simple method. On the basis of the previous work, this project proposes utilization of the rheological phase method to prepare MnOx catalysts with hybrid species. The indentification of MnOx species and Mn valence states will be carried out by chemical titration method and XPS. Meanwhile, the relationship of reaction conditons, Mn valence states, catalytic activity, and SO2 resistance will also be investigated, which would promote the development of low temperature catalysis. To the best of our knowledge, there’s no similar research reported.

Mn基催化剂因其高活性、高选择性和经济性，被认为是最有潜力实现工业应用的低温SCR催化剂之一。由于锰多变的价态和特殊的物理化学性质，MnOx具有多种稳定的化合状态，这种多价态共存的化合状态会影响样品表面原子跃迁和催化反应过程，决定其低温活性的高低。弄清MnOx中Mn价态和不同相的含量，揭示不同价态MnOx的低温NH3-SCR反应机理，对于开发高效催化剂具有重要的指导意义。本项目拟研究不同价态纯相MnOx催化剂的低温催化反应机理，在此基础上，利用流变相法合成多价态共存的MnOx催化剂，通过化学滴定、XPS等方法确定MnOx中Mn价态及其含量，系统研究合成条件（掺杂离子）、化合状态与低温催化活性、抗硫性之间的关联关系，总结MnOx价态调控机制，分析NH3、NO等反应物质在MnOx表面的吸附行为，探索不同化合状态MnOx的催化反应机理，为提高锰基催化剂的低温脱硝性能，推动其工业应用提供理论支持。

Mn基催化剂因其高活性、高选择性和经济性，被认为是最有潜力实现工业应用的低温SCR催化剂之一。本项目基于MnOx具有多种稳定化合态和多价态共存的特性，提出利用化学滴定和XPS相结合的方法定量分析Mn基催化剂中锰离子的价态分布，利用球磨法、流变相法等方法合成单一价态和混合价态的MnOx/TiO2催化剂，并研究了不同价态的MnOx/TiO2的基本性能和催化活性，分析NH3、NO等反应物质在MnO2/TiO2催化剂表面的吸附行为，考察了制备条件、MnOx中锰离子氧化价态及含量与性能之间的关系，结果表明Mn3+、Mn4+更有利于低温活性的提高，且锰盐类型、前驱体pH值、焙烧制度等均会影响产物的物化性能和锰离子价态分布；在此基础上进一步研究了Ce、Fe离子掺杂对MnO2/TiO2催化性能的影响规律，获得MnOx催化剂化合价态调控机制和高活性、高抗硫性的低温SCR催化剂。