The regeneration effect of acid washing on K poisoned SCR catalyst was studied.The experimental catalysts from one power plant in Guangdong province were dipped into KNO3 solution to simulate poisoning.The catalysts before and after regeneration were characterized byvarious methods.Results show that the activity of the catalyst recovered greatly after regeneration

this is partially attributed to the recovery of oxygen adsorbed in the catalyst surface.The toxic element K can be washed away effectively by acid without changing the crystal structure of the catalyst.FTIR results show that Brφnsted acid sites

which was partially recovered after regeneration

are the active chemisorbed sites for NH3 in SCR reaction.However

the stability of regenerated catalyst had declined for the decrease of acid intensity.