Pd-Ag双原子耦合催化剂丙烯-SCR性能及构效关系研究

柴油机尾气NOx排放控制是我国大气污染治理的迫切需求。烃选择性催化还原NOx（HC-SCR）技术是重要的柴油机尾气净化前瞻性技术。Ag/Al2O3是极具应用潜力的HC-SCR催化剂，但该催化剂受活化不含氧HC（如：丙烯）能力的限制，其不含氧HC-SCR低温性能有待提高。本课题拟引入单原子Pd位点（Pd1）为丙烯-SCR反应提供活化丙烯功能，通过Pd1活化丙烯功能与单原子Ag位点（Ag1）还原NOx功能的紧密耦合，改善银铝基催化剂丙烯-SCR低温性能。本项目拟采用新型贵金属锚定方法制备系列Pd1-Ag1/Al2O3双原子催化剂开展研究；结合活性位点结构解析、本征活性规律探索及反应关键中间体变化规律研究，阐明Pd1、Ag1在丙烯-SCR反应中的催化功能及耦合作用；基于催化位点精准结构建模并开展理论计算，明晰Pd1和Ag1催化功能的本质原因，指导高效多功能耦合HC-SCR催化剂设计合成。

NOx emission control from diesel engines is the main target of air pollution control in China. Selective catalytic reduction of NOx utilizing hydrocarbons (HC-SCR) is a forward-looking technology for removing NOx from diesel engines, and Ag/Al2O3 is a HC-SCR catalyst with great application potential. However, the low-temperature HC-SCR performance of Ag/Al2O3 still needs to be improved when using oxygen-free HC (such as propylene) as the reductant, mainly due to weak ability to activate oxygen-free HC. This project intends to improve the low-temperature propylene-SCR performance of Ag/Al2O3 by introducing Pd single-atom sites (Pd1) to Ag1/Al2O3 catalyst, and closely coupling the propylene oxidation function of Pd1 and the NOx reduction function of Ag1. In the project, a new Pd anchoring method will be employed to synthesize a series of Pd1-Ag1/Al2O3 catalysts. The roles of Pd1 and Ag1 sites on propylene-SCR process and their coupling mechanism will be clarified, based on the precise structure characterization of Pd1-Ag1/Al2O3, the intrinsic activity studies, and the studies on the intermediate products in the in-situ propylene-SCR process. The essential reasons for the catalytic function of Pd1 and Ag1 sites can be revealed by the DFT calculation results based on precise structure model, and it will also provide new insights into the design synthesis of efficient HC-SCR catalyst with multifunctional coupling sites.