Assessing impact of real-world aging on Cu-redox half cycles of a Cu-SSZ-13 SCR catalyst via transient response measurements and kinetic modeling

• Published in: Applied catalysis. B, Environmental Environmental, 2022-07, Vol.309 (1), p.121233, Article 121233
• Main Authors: Deka, Dhruba J., Daya, Rohil, Ladshaw, Austin, Trandal, Dylan, Joshi, Saurabh Y., Partridge, William P.
• Format: Article
• Language: English
• Subjects: Aging; Ammonia; Catalysts; Cu-SSZ-13 catalyst field aging; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Monolithic materials; NMR; Nuclear magnetic resonance; Oxidation; SCR Cu-redox cycle; SCR kinetic modeling; Selective catalytic reduction; Sulfur; Sulfur dioxide; Transient response; Transient response methodology
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2022.121233

The SCR reaction on Cu-SSZ-13 is a redox process consisting of a reduction half-cycle (RHC) and an oxidation half-cycle (OHC). Despite extensive efforts to understand hydrothermal aging and sulfur poisoning, the impact of real-world aging on the SCR activity of Cu-SSZ-13 has not been reported. This work employs a transient response methodology consisting of experiments and kinetic models to investigate the SCR redox cycles at intra-catalyst locations of commercial Cu-SSZ-13 monolith catalysts in their degreened and real-world aged states, in the temperature range of 200–450 °C. Moreover, H2-TPR, NH3-TPD, SO2-TPD, ICP-OES and solid-state NMR were performed to investigate the catalyst properties. Sulfur aging and dealumination caused by real-world exposure decreased the reducible Cu density and SCR performance. Real-world aging was found to selectively slow OHC more than RHC, mainly due to lower mobility of the Cu ions coordinated to sulfur-related species leading to decreased formation of Cu-dimers necessary for OHC. [Display omitted] •Real-world exposure causes hydrothermal, phosphorus and sulfur aging of Cu-SSZ-13.•NMR results showed dealumination of real-world aged Cu-SSZ-13 catalyst.•Real-world aged catalyst has higher Z2Cu: Z1CuOH ratio than degreened catalyst.•Real-world aging decreases the active Cu sites and SCR performance of Cu-SSZ-13.•Real-world aging has negligible impact on RHC, but slows down OHC significantly.