Arsenic poisoning is an important reason for deactivation of selective catalytic reduction(SCR) catalysts during SCR denitration process.Once the catalyst is poisoned by arsenic

it is difficult to regenerate by common washing methods.To solve this problem

this article investigates the influence of valence state and content of arsenic on activity of the SCR catalysts

by taking the arsenic poisoned catalysts as the research object.Moreover

the deactivated catalysts were washed and regenerated by ammonium peroxydisulfate with concentration of 1.0 mol/L and sodium carbonate with concentration of 1.0 mol/L.The results show that

the arsenic species mainly exist in valence state of pentavalent(As~(5+)) on the arsenic poisoned catalysts' surface

and the content of As has a significant effect on the catalytic denitrification activity.Importantly

as the mass ratio of As to V was increased from 2.04 to 3.52

the denitrification efficiency decreased by 15.71%.Besides

the removal rate of As was 66.0% when washed by Na_2CO_3 aqueous

while that of the ammonium peroxydisulfate was merely 25.3%.The reason was probably that arsenic on the catalyst surface could convert into Na_3AsO_4

which was removed easily due to its well solubility in H_2O.Consequently

the catalytic denitrification efficiency recovered.