Photo-oxidation and Adsorption of Hg~0 in Flue Gases by WO_3 Modified TiO_2 at High Temperatures

摘要

This study established a HgCl_2 on-line measurement system to investigate the photo-oxidation efficiency and adsorption efficiency at 160°C with Hg~0 influent concentration of 100 μg/m~3. The on-line monitor can detect two different final products of Hg~0, which presents two possible reaction path. One is the oxidation route that the Hg~0 was transformed to gaseous HgCl_2 entering to the flue gases, the other is the Hg~0 was adsorbed on the surface of the photocatalysts. Single gaseous component of HCl and O_2 was demonstrated to enhance the adsorption efficiency and oxidation efficiency of Hg~0 by 5%WO_3/TiO_2. In the bicomponents of HCl and O_2, the effects of near-UV, HCl concentration, and O_2 concentration on the total removal efficiency of Hg~0 were slight, but significant for the oxidation and adsorption efficiency of Hg~0. The total removal efficiency of Hg~0 was not influenced by the addition of NO to gaseous components of HCl and O_2, which indicated that the bicomponents of HCl and O_2 diminished the adverse effect of NO. However, the oxidation efficiency and adsorption efficiency of Hg~0 were influenced by addition of NO. Without near-UV irradiation, addition of SO_2 inhibited the total removal efficiency, the adsorption efficiency, and the oxidation efficiency of Hg~0 by 5%WO_3/TiO_2, even if the bicomponents of HCl and O_2 were present in the flue gases. Near-UV irradiation was benefit to diminish the inhibition caused by addition of SO_2.