Excellent low-temperature activity and resistance to K-poisoning in NH3-SCR de-NOx reaction over CeSnOx with phosphorylation treatment catalyst

Resistance to alkali metal poisoning remains a challenge for Ce-based denitration (de-NOx) catalysts. In this paper, improved low-temperature performance and resistance to K poisoning were achieved by phosphorylating CeSnOx. The activity tests revealed that the phosphorylated CeSnOx (3 wt%P/CeSn) exhibited over 90 % NO conversion at 190–450 °C and >90 % NO conversion at 240–400 °C even after K poisoning. The mechanism of phosphorylation treatment against K poisoning was investigated by many characterizations and DFT calculation. The results showed that the phosphorylation treatment facilitated the interaction between Ce and Sn, and K interacts more preferentially with PO43- species. This prevents K from destroying the Ce-O-Sn structure to form a Ce-O-K structure, which in turn maintained the catalyst's redox properties. Moreover, the phosphorylation treatment supplemented the acidity of 3 wt%P/CeSn compared with CeSnOx. This effectively mitigated the reduction of acidity caused by K and ensured the adsorption and activation of NH3 on the catalyst surface.