Abstract
Cu-SSZ-13 has been generally considered as the predominant commercial selective catalytic reduction (SCR) catalyst in the NH3-SCR reaction because of its superior activity and durability. However, in real applications, SCR catalysts readily undergo hydrothermal aging and sulfur poisoning. In this work, the deactivation and regeneration of a commercial Cu-SSZ-13 catalyst was investigated for SO2 exposures during hydrothermal aging and the effect of different regeneration temperatures was compared. By using XRD, SEM, H2-temperature programmed reduction (TPR), X–ray photoelectron spectra (XPS) and NH3-temperature programmed desorption (TPD) analysis, it was found that SO2 poisoning influenced the chabazite (CHA) structure even if regeneration cannot restore its original structure, the redox ability and ammonia storage performance also influenced by sulfation and the regeneration process. Moreover, the extent of a decrease in redox ability was more severe than acidity, suggesting that the amount of isolated Cu2+ and Cu+ reduction was responsible for irreversible deactivation over the Cu-SSZ-13 catalyst. Combined with the analysis of Ea values and pre-exponential factor of the SCR reaction, a more likely explanation for the irreversible deactivation was that active sites were lost mostly in sulfated and regenerated process sites.
Highlights
Selective catalytic reduction with ammonia (NH3 -selective catalytic reduction (SCR)) has been successfully developed as a promising technology for reducing NOx emitted in combustion gas emissions from automotive sources [1,2,3]
By using different characterization techniques, we investigated the changes of the framework structure, the acid and active sites of the Cu-SSZ-13 with different regeneration temperature
Confirmed by the diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) and thermo the sulfur species on the zeolite catalysts could be observed after F-Cu treating by SO2 feed, and the amount of SO2 monotonically decreased with regeneration temperature increasing
Summary
Selective catalytic reduction with ammonia (NH3 -SCR) has been successfully developed as a promising technology for reducing NOx emitted in combustion gas emissions from automotive sources [1,2,3]. Numerous studies have been carried out to learn about the reversible and irreversible damage of Cu-SSZ-13 such as dealumination of the framework structure, accumulation and distribution of different state copper species when Cu-SSZ-13 is subjected to sulfur poisoning [11,12,13]. Cu-SSZ-13 over long-term SO2 exposure, thereby providing guidance for applying Cu-SSZ-13 in the diesel after-treatment system
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