The effect of sulfate species on the activity of NH3-SCR over Cu/SAPO-34

• Published in: Applied catalysis. B, Environmental Vol. 204; pp. 239 - 249
• Main Authors: Wang, Chen, Wang, Jun, Wang, Jianqiang, Yu, Tie, Shen, Meiqing, Wang, Wulin, Li, Wei
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05-05-2017
• Subjects: Cu/SAPO-34; Deactivation mechanism; Sulfate species; Sulfur poisoning; Deactivation mechanism; Cu/SAPO-34; Sulfate species; Sulfur poisoning
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2016.11.033

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•Both copper sulfate and ammonia sulfate species are formed on the Cu2+ sites.•The sulfated catalyst shows lower conversions due to reduced number of Cu2+ sites.•The deactivation mechanism by two types of sulfate species are the same.
The deactivation mechanism by different types of sulfate was investigated for the selective catalytic reduction of NOx on Cu/SAPO-34 catalyst. A Cu/SAPO-34 catalyst was treated with 50ppm SO2 alone at 150 and 250°C or in the presence of a SCR feed at 250 and 350°C. Copper sulfate was found on all sulfated catalysts, but ammonia sulfate was found only on the catalyst sulfated in the SCR feed at 250°C. In situ DRIFTs results show that both copper sulfate and ammonia sulfate species are formed on the isolated Cu2+ sites. All sulfated catalysts have lower NOx conversions compared with the unsulfated catalysts due to reduced number of active sites. However, their apparent activation energies for the SCR reaction remain the same, and their turnover frequencies are identical. This suggests that the deactivation mechanism is similar regardless of the type of sulfate species. On the other hand, it was found that ammonia sulfate was easier to remove than copper sulfate by a desulfation treatment at 600°C, resulting in a larger extent of activity recovery.