Enhanced Low-Temperature Activity and Hydrothermal Stability of Ce-Mn Oxide-Modified Cu-SSZ-39 Catalysts for NH3-SCR of NOx

作者：Ahui Tang, Fuzhen Yang, Ying Xin, Xiaoli Zhu, Yu Long, Shuai Liu, Dongxu Han, Junxiu Jia, Yaning Lu, Zhenguo Li, Zhaoliang Zhang · 发表于：Catalysts · 年份：2023 · DOI：10.3390/catal14010010 · 被引用次数：14 · 研究领域：Catalytic Processes in Materials Science、Catalysis and Oxidation Reactions、Nanomaterials for catalytic reactions

Cu-SSZ-39 zeolite with an AEI structure exhibits excellent hydrothermal stability and can be a potential alternative to Cu-SSZ-13 zeolite SCR catalysts for NOx removal in diesel vehicles. However, the inferior low-temperature performance of Cu-SSZ-39 leads to substantial NOx emissions during the cold-start period, impeding its practical application. In this study, Ce-Mn oxide-modified Cu-SSZ-39 catalysts (CeMnOx/Cu-SSZ-39) and references (CeO2/Cu-SSZ-39 and MnOx/Cu-SSZ-39) were prepared by the ion-exchange of Cu ions followed by impregnation of the oxide precursors, with the aim of enhancing the NH3-SCR performance at low temperatures. The modified catalysts exhibited improved low-temperature activity and hydrothermal stability compared to the unmodified counterpart. In particular, CeMnOx/Cu-SSZ-39 showed the highest activity among the three catalysts and achieved NOx conversions above 90% within the temperature range of 180 °C to 600 °C, even after undergoing hydrothermal aging at 800 °C. Experimental results indicated that the synergistic effect between Ce and Mn in CeMnOx improves the redox properties and acidity of the catalyst due to the presence of Ce3+, Mn4+, and abundant adsorbed oxygen species, which facilitate low-temperature SCR reactions. Furthermore, the interaction of CeMnOx with Cu-SSZ-39 stabilizes the zeolite framework and hinders the agglomeration of Cu species during the hydrothermal aging process, contributing to its exceptional hydrothermal stability. The...