Oxidation of Elemental Mercury with Non-Thermal Plasma Coupled with Photocatalyst

A promising approach has been developed to oxidize and remove elemental mercury species from coal-fired flue gas. The oxidation of gas-phase elemental mercury (Hg-0) by non-thermal plasma coupled with photocatalyst has been studied, employing both dielectric barrier discharge (DBD) of gas mixture and direct ultraviolet (UV) irradiation on titania powder surfaces. The nanocrystalline titania catalysts have been prepared by TiCl4 hydrolysis method under three different calcination temperatures and were characterized by SEM and XRD techniques. The effects of the operating parameters, such as the moisture concentrations, UV light intensity and the applied voltage of the DBD reactor system, were investigated. Results indicated that the presence of TiO2 under both direct UV irradiation and DBD system promoted the Hg-0 oxidation and the best photocatalytic activity of anatase TiO2 which was calcined at 600 degrees C was found in our tests. Compared the oxidation with non-thermal plasma alone, the oxidation efficiency increased 18.7%similar to 26.3% with the method coupled with photocatalyst. With the increasing of water vapor concentrations, UV light intensity, the oxidation of elemental mercury was significantly enhanced in the DBD-photocatalytic reactor system.