高效稳定的新型Cu基小孔分子筛NH3-SCR催化剂研究

Excellent activity and hydrothermal stability are two requirements for Cu based small-pore zeolite NH3-SCR catalysts applied for NOx removal from diesel vehicles. This project focused on the improvement of low-temperature NH3-SCR activity and hydrothermal stability of new-type Cu based small-pore zeolites, i.e., Cu-SSZ-50 and Cu-SSZ-39, adding a second metal element in Cu based zeolites and using Al-rich zeolite framework structure. In this way, the active Cu species were anchored in the zeolites, and high hydrothermal stability and NH3-SCR activity will be achieved. The intrinsic properties, such as zeolite framework structure, Si/Al, Cu distribution and coordination state, will be studied, as well as its relationship with NH3-SCR performance, hydrothermal stability and sulfur durability. Based on the summary of general laws and characteristics of these small-pore zeolites applied in NH3-SCR reaction, the design and synthesis of new-type zeolites can be guided. The catalytic materials for practical application on diesel engines can be developed eventually.

优异的活性和水热稳定性是Cu基小孔分子筛NH3-SCR催化剂应用于柴油车NOx超低排放的两大必要条件。本项目针对现有Cu-SSZ-50、Cu-SSZ-39等新型小孔分子筛催化剂水热稳定性、NH3-SCR活性不足的问题，以富Al分子筛骨架构筑、Cu基分子筛催化剂上第二金属元素修饰等为主要研究策略，以丰富分子筛骨架上活性物种Cu的锚定位点，并实现其强化锚定，从而实现新型小孔分子筛材料的水热稳定性、NH3-SCR性能的提升。采用多种原位、离位表征与量化模拟相结合的研究手段，深入剖析分子筛骨架结构、Si/Al、Cu物种价态与配位状态等内在特征，及其与NH3-SCR性能、水热稳定性、抗硫性能等的关联，以指导高效稳定的新型NH3-SCR催化剂的设计，为柴油车NOx超低排放的NH3-SCR催化剂合成提供基础数据和理论支持。

氮氧化物（NOx）是大气细颗粒物（PM2.5）和臭氧（O3）复合污染形成的重要前体污染物。控制以柴油车为代表的移动源尾气NOx排至关重要。NH3选择性催化还原是NOx净化的主要技术手段，核心是NH3-SCR催化剂。本项目以铜基小孔分子筛催化剂为研究对象，在原子层面揭示了铜基小孔分子筛催化剂的水热老化机制和NH3-SCR反应机制;总结了高效稳定的铜基小孔分子筛的普适性规律. 通过过渡金属调控，骨架构型调控等，指导了系列催化剂（Cu-SSZ-13、Cu-SSZ-39、Cu-SSZ-50和Cu-KFI）的优化设计，提升了NH3-SCR活性和水热稳定性。本项目成果为未来柴油机尾气NOx净化提供了理论基础和技术策略。