铜菱沸石分子筛（Cu-CHA）是氨选择性还原（NH3-SCR）净化柴油车尾气氮氧化物（NOx）的重要催化材料，但其低温（150～200 °C）活性不足制约NOx高效脱除。本项目旨在通过强化Cu-CHA分子筛(以Cu-SSZ-13为例)活性位点在反应条件下的动态限域迁移来提升其低温NH3-SCR活性。采用先进分子筛合成策略，调变SSZ-13骨架铝原子间距、共存骨架外阳离子种类和数量，优化Cu位点在CHA结构中的落位及微观配位环境，实现对Cu位点动态限域迁移性能的强化；发展和运用原位介电模量谱及其和红外/紫外可见光谱的耦合表征技术，结合密度泛函理论/从头算分子动力学模拟、反应动力学测试，在分子层面阐明Cu活性位点动态限域迁移的强化机制及其对Cu-CHA低温NH3-SCR活性的提升机制，为高效Cu-CHA低温NH3-SCR催化剂的理性设计和精准合成提供理论和实验依据。

Abatement of nitrogen oxide emissions (NOx) from diesel-powered heavy-duty vehicles is one of the key challenges in the control of air pollution in China. Although ammonia-assisted selective catalytic reduction (NH3-SCR) using copper ion-exchanged chabazite zeolite (Cu-CHA) as catalyst has been proved to be highly effective for automotive NOx aftertreatment, its performance at 200 °C and below is hindered by the insufficient NH3-SCR activity of current-generation Cu-CHA zeolite catalyst. In this project, we intend to improve the low-temperature NH3-SCR activity of Cu-CHA (Cu-SSZ-13 as an example) by reinforcing the reaction-driven dynamic local movement of Cu active sites within the zeolite catalyst. The proximity of aluminum T-atoms in the CHA framework, as well as the type and amount of alkali or alkali earth co-cations will be varied to rationalize the coordinating environment of Cu active sites, in order to manipulate the electrostatic tethering and, in turn, to enhance the localized movement of Cu sites within CHA. Dielectric impedance-based in situ modulus spectroscopy and its coupling with diffuse reflection infrared/ultraviolet-visible spectroscopy, density-functional theory/ab initio molecular dynamics simulations, NH3-SCR reaction kinetics will be integrated to unveil potential correlations among the CHA framework structure, the local movement of Cu sites, and the low-temperature NH3-SCR performance for the Cu-SSZ-13 catalysts, aiming at rational design and precision synthesis of new-generation Cu-CHA catalysts with boosted NH3-SCR efficiency at low temperatures.