Characteristics of SCR Catalysts for the Oxidation of Gaseous Elemental Mercury

摘要

The activity of several kinds of commercial SCR catalyst was examined for the oxidation of elemental mercury to ionic mercury under SCR conditions. The physicochemical properties of SCR catalyst such as BET surface area, pore size distribution and compositions were examined to understand their roles for mercury oxidation. Commercial SCR catalyst with about 8 wt% WO{sub}3 revealed much higher activity for mercury oxidation than the catalyst without WO{sub}3. It may indicate that WO{sub}3 as well as V{sub}2O{sub}5 has an activity for mercury oxidation. The presence of HCl in flue gas significantly increased the activity of commercial SCR catalyst for Hg oxidation. The activity of SCR catalyst for Hg oxidation revealed intimate relation with the amount of adsorbed mercury on the catalyst surface. The larger the amount of adsorbed mercury was, the higher the catalytic activity was. It means the involvement of mercury adsorption step in the reaction mechanism of mercury oxidation under SCR reaction conditions.