In this work, the commercial selective catalytic reduction (SCR) catalyst V2O5-MoO3/TiO2 was sulfureted with H2S to improve both its capability for elemental mercury (Hg0) removal at low temperatures and its resistance to SO2 and H2O. Hg0 removal over both V2O5-MoO3/TiO2 and sulfureted V2O5-MoO3/TiO2 involved the catalytic oxidation of Hg0 to HgCl2 and the chemical adsorption of gaseous Hg0; therefore, the effect of sulfuration on Hg0 chemical adsorption and the catalytic oxidation of Hg0 to HgCl2 over V2O5-MoO3/TiO2 and its resistance to SO2 and H2O were investigated using Hg balance analysis. Kinetic analysis showed that the rates of the chemical adsorption and oxidation of Hg0 were both in direct proportion to the concentration of physically adsorbed Hg0. The physical adsorption of gaseous Hg0 on V2O5-MoO3/TiO2 was remarkably promoted after sulfuration, and the physical adsorption of gaseous Hg0 over sulfureted V2O5-MoO3/TiO2 was scarcely inhibited by SO2 and H2O. Therefore, the performance of V2O5-MoO3/TiO2 for Hg0 removal and its resistance to SO2 and H2O were both improved after sulfuration. Even more remarkably, sulfureted V2O5-MoO3/TiO2 can adsorb gaseous HgCl2, which resulted from Hg0 oxidation. Therefore, sulfureted V2O5-MoO3/TiO2 showed an excellent performance to recover Hg0 from coal-fired power plants, which can then be converted to liquid Hg.
Keywords: Hg0 adsorption; Hg0 oxidation; Hg2+ adsorption; effect of sulfuration; resistance to H2O and SO2; sulfureted V2O5−MoO3/TiO2.