为满足柴油车冷启动NOx减排要求，解决Urea-SCR技术低温下（<150℃）不能正常脱硝的弊端，本项目设计一步法合成原子级分散Pd改性的多级孔SSZ-13分子筛NOx被动吸附剂（Passive NOx adsorber，PNA）。向SSZ-13合成凝胶中引入Pd-络合物，调控Si/Al创造足够数量的离子交换位点，使Pd以原子级Pd2+锚定于分子筛离子交换位点上。同时向合成凝胶中引入造孔剂，调控分子筛孔道结构，从而调控分子筛骨架、Pd物种及NOx三者间的相互作用强度，实现对NOx在指定温度范围吸附、快速高比例在SCR活性温度脱附的可控储释。结合DFT计算和实验结果，探究分子筛限域效应对Pd物种和NOx吸脱附的影响，明晰影响NOx可控储释的关键因子，厘清多级孔Pd-SSZ-13的构效关系。深入探究多级孔Pd-SSZ-13上的微观反应，揭示NOx储释机制，为PNA设计开发提供有效的理论依据。

To meet the requirement for reduction of NOx emission during diesel vehicle cold-start and to solve the drawback of Urea-SCR technology that can't denitrify normally at low temperature (< 150°C), the atomic dispersed Pd modified hierarchical SSZ-13 molecular sieve as NOx adsorber (PNA) is innovatively designed and synthesized in this study. By introducing Pd-complex into the SSZ-13 synthetic gel and regulating Si/Al to create a sufficient amount of exchange sites are provided for the ion exchange of Pd with molecular sieve. Therefore, Pd can be stabilized in the form of atomic Pd2+ at the molecular sieve ion exchange site. The pore structure of SSZ-13 molecular sieve is regulated by introducing pore former into the synthetic gel to achieve the regulation of interaction strength between molecular sieve framework, Pd species and NOx, and NO adsorption in the specified temperature range, fast high proportion desorption at SCR active temperature and controllable storage and release of NOx over Pd-SSZ-13. Based on DFT calculation and experimental results, the spatially confined effects of SSZ-13 molecular sieve on Pd species and NO adsorption are explored to clarify the key factors of NO controllable adsorption and desorption, the structure-performance of hierarchical Pd-SSZ-13 in NOx storage and release. In-depth study of the microscopic reaction on hierarchical Pd-SSZ-13 molecular sieve is carried out to reveal the mechanism of NOx adsorption and desorption, which provides an effective theoretical basis for the design and development of PNA.