Deactivation mechanism of KCl and K2SO4 poisoned V2O5/WO3-TiO2 catalyst on gaseous elemental mercury oxidation

In this paper, the mercury oxidation performance of KCl or K2SO4 poisoned V2O5/WO3-TiO2 catalysts was investigated. And the poisoned samples were prepared by the incipient-wetness impregnation method. The effects of temperature, catalyst poisoning degree and flue gas composition on the catalyst oxidation were investigated respectively. Results demonstrated that Cl- and SO42- doped catalysts would mitigate the effect of catalyst potassium poisoning on the mercury oxidation. Further research on BET and XRD demonstrated that the catalysts surface did not change significantly after KCl and K2SO4 poisoning. Deactivation on physical side was not the main root cause leading to catalyst deactivation. Hg-TPD (Hg temperature-programmed desorption) results showed that the acidic sites formed by SO42- could promote the adsorption of Hg-0 on the catalysts surface. XPS results showed that both Cl- and SO42- could promote the formation of surface active O-a. Based on the experimental results and analysis, the KCl and K2SO4 poisoned V2O5/WO3-TiO2 catalysts mechanism on mercury oxidation was derived.