Weichai Power Co., Ltd.
State Key Joint Laboratory of Environment Simulationand Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences
Ganjiang Innovation Academy, Chinese Academy of Sciences
School of Chemistry and Chemical Engineering, Nanchang University
Center forExcellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences

柴油车排放的氮氧化物(NOx) 对我国大气污染具有重要贡献。 NH3选择性催化还原 NOx(NH3-SCR)是目前柴油车广泛采用的 NOx净化技术,而 Cu-SSZ-13 催化剂由于兼具优异的 NH3-SCR 活性和水热稳定性而被用于国六柴油车 NOx排放控制。 在柴油车后处理系统中,氧化催化剂的贵金属迁移会造成 Cu-SSZ-13 催化剂中毒,进而影响其活性和选择性等性能。 本研究系统考察了不同贵金属种类和富集浓度对 Cu-SSZ-13 催化剂性能的影响,以及水热老化对贵金属中毒的再生作用。 当贵金属中毒达到一定程度时,Cu-SSZ-13 的催化性能(尤其是高温活性)会受到较大影响;水热老化会一定程度恢复贵金属中毒催化剂的 NOx 净化性能,但可以促进副产物N2O 的生成;贵金属 Pt 和 Pd 对 Cu-SSZ-13 活性影响程度和中毒机制相似。 XRD(X 射线衍射)、N2物理吸附表征结果表明,贵金属对 Cu-SSZ-13 的结构影响不大,但会轻微降低催化剂的比表面积和孔容;通过 NH3 氧化和 NO 氧化实验可知,贵金属会促进副反应的发生,额外消耗NH3-SCR 体系中的还原剂 NH3,从而降低 Cu-SSZ-13 的 NOx净化性能。 本研究有助于理解贵金属对 Cu-SSZ-13 催化剂的中毒作用及其机制。

Nitrogen oxides (NOx) from diesel exhaust can induce severe air pollution problems. Selec⁃tive catalytic reduction of NOx with NH3( NH3 -SCR) is the dominant technology for NOx abatementfrom diesel vehicles, and Cu-SSZ-13, with excellent NH3 -SCR activity and hydrothermal stability,has been widely used as the NH3 -SCR catalyst on diesel vehicles of China VI. In the aftertreatmentsystem of diesel vehicles, Cu-SSZ-13 catalyst can be poisoned by the migration of noble metals fromoxidation catalysts, and its NH3-SCR performance will be affected. In this study, the effects of noblemetals with different types and concentrations on the performances of Cu-SSZ-13 catalyst were investi⁃gated, and the regeneration effects of hydrothermal aging on noble metal poisoning were also analyzed.When the loading amount of noble metal reached a certain level, the performance of Cu-SSZ-13 wassignificantly affected, especially the high temperature activity. Hydrothermal aging could restore theNOx conversion of poisoned catalyst to a certain extent, but the formation of N2O as a byproduct waspromoted. Noble metals of Pt and Pd had similar effects on Cu-SSZ-13. The results of XRD (X-raydiffraction) and N2 physical adsorption showed that the noble metals had no obvious influence on thestructure of Cu-SSZ-13, but they could slightly reduce the specific surface area and pore volume ofthe catalyst. According to the results of separate NH3 oxidation and NO oxidation, noble metalpoisoning could promote the occurrence of side reactions and induce over consumption of NH3, thus de⁃creasing the NOx conversion over Cu-SSZ-13 due to lack of reducing agent. This study is helpful to un⁃derstand the poisoning effects and mechanism of noble metals on commercial Cu-SSZ-13 catalyst forNH3-SCR.

国家自然科学基金资助项目(51978640)

薛森,丁文庆,韩学旺, 等. 贵金属中毒对 Cu-SSZ-13 分子筛 NH3 -SCR 性能的影响[J]. 能源环境保护,2023, 37(6): 36-42.

XUE Sen, DING Wenqing, HAN Xuewang, et al. Effects of noble metal poisoning on NH3-SCR performances ofCu-SSZ-13 catalyst[J]. Energy Environmental Protection, 2023, 37(6): 36-42.