Influence of coke deposition by propene poisoning on Cu-SSZ-13 catalyst for selective catalytic reduction of NOx with NH3

Abstract

In this study, Cu-SSZ-13 catalyst was prepared via ion exchange method and then treated with 1000 ppm or 2000 ppm propene (C3H6) poisoning for 20 h. The influence of coke deposition by C3H6 poisoning on Cu-SSZ-13 catalyst for selective catalytic reduction of NOx with NH3 was investigated with standard NH3-SCR conditions based upon the simulated gas experimental platform. The results showed that NOx reduction activity was slightly affected after 1000 ppm C3H6 poisoning while the NOx conversion was remarkably lower than that of fresh catalyst below 400 °C after 2000 ppm C3H6 poisoning. However, the NOx reduction activity was recovered and even mildly higher than the original level beyond 400 °C. The existence of coke deposition was confirmed by TG-DTA analysis. 2000 ppm C3H6 poisoned catalyst had more coke deposition than 1000 ppm C3H6 poisoned catalyst. XRD and BET results showed that the surface area of the catalyst was decreased by blocking the pore channels, especially for 2000 ppm C3H6 poisoned catalyst, but the structure of the catalyst was not collapsed after C3H6 poisoning. XPS and NH3-TPD results illustrated that Cu2+, CuO, Lewis and Brønsted acid sites were more susceptible to be affected under 2000 ppm C3H6 poisoning. NH3 oxidation activity was weakened slightly on poisoned catalysts above 400 °C in NH3-TPO. From the In-situ DRIFTs results, the basic mechanism of inhibition by C3H6 poisoning on Cu-SSZ-13 catalysts was attributed to less available NH3 used in SCR reaction.