OXIDATION OF ELEMENTAL MERCURY USING IN SITU GENERATED TiO_2 AND UV LIGHT

摘要

The oxidation of gas-phase elemental mercury was examined using UV light and in-situ generated TiO_2 catalyst particles. Agglomerated particles, with a high specific surface area, were generated in situ by injecting a gas-phase precursor into a high temperature furnace reactor. Titania particles in the presence of UV (315～400nm) irradiation effectively oxidize mercury, but this requires a long residence time. As the residence time is shortened, the capturing efficiency of Hg~0 diminishes, which is dependent on SO_2 gas. In a UV reactor, the photochemical reaction of the titanium particles simultaneously affects the flying particles in the quartz reactor and the TiO_2 particles on the quartz reactor wall. Short wavelength UV light, 254+185 nm, generates ozone as well as OH radicals in the photochemical reactor, and TiO_2 particles accelerate the oxidation of both of these species. Therefore, even though the residence time became shorter, this had no effect on the capture efficiency. In addition, SO_2 and NO gas interrupt the oxidative reaction of elemental mercury.