S.M. Lee, D.W. Kim, I.Y. Lee, J.B. Lee, M.H. Kim, S.W. Ham
elemental mercury, SCR, oxidation, hydrogen chloride
In the present study, the performance of SCR catalyst for the oxidation of mercury was studied to understand the mechanism of mercury oxidation on SCR catalyst. A variety of V2O5-based TiO2 catalysts was evaluated for the simulated flue gas containing NO, NH3, SO2 which are typical components in SCR process. HCl with variable concentration was also present in the flue gas to examine the effect of HCl on mercury oxidation. The presence of HCl in flue gas significantly increased the activity of commercial SCR catalysts for Hg oxidation as shown in Fig. 1. The activities of SCR catalysts for Hg oxidation revealed intimate relation with the amount of adsorbed Hg on the catalyst surface. The larger the adsorbed mercury was, the higher the catalytic activity was. It indicates the involvement of Hg adsorption step in the reaction mechanism of mercury oxidation under SCR reaction conditions. The activities of SCR catalysts for Hg oxidation also depended on the surface structures of vanadia as well as the content of V2O5. Therefore, the physicochemical properties of SCR catalyst such as pore size distribution of TiO2, V2O5 content and its structure on the catalyst surface was examined to understand their roles for mercury oxidation.