Insight into the effect of phosphorus poisoning of Cu/zeolites with different framework towards NH3-SCR
Aiyong Wang, Maria Elena Azzoni, Joonsoo Han, Kunpeng Xie, Louise Olsson
Abstract
Cu/zeolites were prepared to elucidate the effect of phosphorus poisoning on different zeolite framework structures for NH 3 -SCR. The results show that there are significant differences in phosphorus poisoning depending on the zeolite framework structure. The PO 3 − /PO 4 3− species gradually decreased along with an increase in P 2 O 5 in the following order: Cu/SSZ-13, Cu/ZSM-5, and Cu/BEA. One possible reason could be the increased pore size of these zeolites, which results in less steric hindrance for larger P 2 O 5 species. P 2 O 5 is suggested to enhance the redox ability of Cu ions, which results in an increase in low-temperature activity in NH 3 -SCR, whereas Cu ions were significantly poisoned by PO 3 − /PO 4 3− , resulting in low-temperature deactivation. Furthermore, the effect of phosphorus poisoning on the structure of Cu/ZSM-5 was found to be much greater than that of Cu/BEA and Cu/SSZ-13, possibly due to phosphorus attacked the surface defects of the zeolite, causing local expansion and cracking.