Insight into SO2 poisoning and regeneration of one-pot synthesized Cu-SSZ-13 catalyst for selective reduction of NOx by NH3

The effects of SO 2 on an one-pot synthesized Cu-SSZ-13 catalyst for selective reduction of NO x by NH 3 were examined. The addition of SO 2 inhibited NO x conversion significantly below 300 °C, while no effect on NO x conversion was observed above 300 °C. TGA, TPD , and XPS results showed that the deactivation was caused by the formation of (NH 4 ) 2 SO 4 , SO 2 chemisorption on the isolated Cu 2+ ion sites, as well as the formation of CuSO 4 -like species. Among them, the site-blocking effect of (NH 4 ) 2 SO 4 on Cu 2+ was the primary reason for deactivation. Fortunately, 89% of deNO x activity of the poisoned catalyst was recovered after thermal treatment at 500 °C in air, where (NH 4 ) 2 SO 4 was completely decomposed. The activity was further recovered with regeneration temperature increasing to 600 °C, removing the adsorbed SO 2 on the Cu 2+ sites. The regeneration at 600 °C could not recover the activity completely, because of the high stability of CuSO 4 -like species.