The performance of Ag doped V2O5–TiO2 catalyst on the catalytic oxidation of gaseous elemental mercury

Abstract

To improve the catalytic oxidation ability for gaseous elemental mercury (Hg⁰), silver was introduced to V₂O₅–TiO₂ catalysts. The catalysts were prepared by an impregnation method with various additives to obtain well distributed silver nanoparticles on the carrier. It was found that doping silver onto V₂O₅–TiO₂ can significantly improve the catalytic oxidation efficiency of Hg⁰, and the redox temperature range for Hg⁰ oxidation was enlarged markedly (150–450 °C). The addition of polyvinylpyrrolidone (PVP) during the preparation of the catalysts can improve the dispersion of silver nanoparticles more effectively, which resulted in a higher Hg⁰ oxidation efficiency up to 90%. However, the oxidation of Hg⁰ on the catalyst was slightly inhibited due to the larger silver nanoparticles when the ionic liquid (IL) [bmim][BF₄] was used as the additive. The characterization results indicated that V can be induced to a higher oxidation state in the presence of silver nanoparticles, and the transformation trend of TiO₂ from the anatase to rutile phase caused by Ag can be minimized in the presence of PVP or ILs. Meanwhile, the mechanisms of the elemental mercury oxidation at various temperature ranges were discussed.