Identification of sulfate species and their influence on SCR performance of Cu/CHA catalyst

• Published in: Catalysis science & technology Vol. 7; no. 7; pp. 1523 - 1528
• Main Authors: Su, Wenkang, Li, Zhenguo, Zhang, Yani, Meng, Chenchen, Li, Junhua
• Format: Journal Article
• Language: English
• Published: 2017
• Subjects: Catalysts; Deactivation; Exhaust; Formations; Simulation; Sulfates; Sulfation; Zeolites
• ISSN: 2044-4753; 2044-4761
• DOI: 10.1039/C7CY00302A

An investigation into sulfate formation on Cu/CHA zeolites was conducted to confirm the main sulfate species that deactivate the catalyst. SO 2 -TPD and controlled regeneration of poisoned catalysts were carried out to study the physicochemical properties of the sulfates formed under different conditions. The results revealed that three sulfate species existed on the catalyst surface, namely H 2 SO 4 , CuSO 4 and Al 2 (SO 4 ) 3 . H 2 O and NH 3 -SCR feed could improve the formation of H 2 SO 4 via an increase in the reaction rate of SO x with protons and decrease the thermal stability of all sulfates via the protons' strong polarization effect. The poisoning effect of ammonium sulfate was more emphasized during sulfation in the presence of simulated exhaust gas. Additionally, in contrast to Cu/SSZ-13, Cu/SAPO-34 favored the formation of stable Al 2 (SO 4 ) 3 species, which resulted in unrecoverable SCR activity in an inert atmosphere below 650 °C.