Direct incorporating small amount of Ce (III) in Cu-SAPO-18 catalysts for enhanced low-temperature NH3-SCR activity: Influence on Cu distribution and Si coordination

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 435; p. 134890
• Main Authors: Wu, Qin, Fan, Chi, Wang, Ya, Chen, Xiaoping, Wang, Guimin, Qin, Zhengxing, Mintova, Svetlana, Li, Junhua, Chen, Jianjun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2022; Elsevier
• Subjects: Acidity; Active Cu2+ ions; Catalysis; Chemical Sciences; CuCe-SAPO-18; Environmental Engineering; Environmental Sciences; Low-temperature activity; One-pot synthesis; One-pot synthesis; Low-temperature activity; Acidity; CuCe-SAPO-18; Active Cu2+ ions
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.134890

The Ce3+ ions were found to affect the coordination of Si and Al atom in the AEI-type framework structure leading to an increase of both the number of active Cu2+ species and the acidity of the CuCe-SAPO-18 catalysts that are beneficial for the low-temperature (<200 ℃) NH3-SCR activity and hydrothermal stability. [Display omitted] •One-pot synthesis of CuCe-SAPO-18 catalysts were firstly reported.•A small amount of cerium (0.13–0.31 wt%) could enhance the low-temperature SCR performance considerably.•Cerium species reside in the ion-exchange sites of Cu-SAPO-18.•The valence state of cerium was identified to be + 3 rather than + 4.•Cerium species affect the Cu distribution and Si coordination of Cu-SAPO-18. The reduction of NOx emission during the cold start period of diesel vehicles requires special attention in accordance with the emission regulations. In this work, the direct incorporation of cerium and copper in SAPO-18 catalyst with AEI type framework structure (CuCe-SAPO-18) resulting in a substantial enhancement of the performance in the low-temperature NH3-SCR reaction (<200 ℃). A small amount of cerium (0.13–0.31 wt%) broadened the reaction temperature range of use and increased the hydrothermal stability of the catalyst considerably. The cerium species was introduced in the ion-exchange sites of Cu-SAPO-18 in the form of Ce3+ ions even with high loading (3.15 wt%). The Ce3+ ions were found to affect the distribution of silicon and aluminum atom coordination (29Si NMR, 27Al MAS NMR) in the AEI-type skeleton structure leading to an increase of both the amount of active Cu2+ species and the acidity of the CuCe-SAPO-18 catalysts that are beneficial for the NH3-SCR reaction.