Study on the oxidation efficiency of elemental mercury in flue gas by SCR De-NOx catalyst.
The oxidation efficiency of elemental mercury (Hg0) by fresh and 40000 h SCR (Selective Catalytic Reduction) catalysts was studied with the help of simulated experiments under oxidation and SCR conditions, respectively. The structural and textural properties of the catalysts were characterized by various techniques, including N2 adsorption/desorption, SEM-EDS, FT-IR, and ion chromatography. It was found that the Hg0 oxidation efficiency over the 40000 h catalyst is about 5%-20% lower than that of the fresh one under the oxidation condition (with HCl and O2), whereas it just decreases by about 5%-10% under the SCR condition (when NH3 and NO are added). The particles agglomeration phenomenon was observed for the 40000 h catalyst, of which the BET, V content, and V5+=O quantity decrease to some extent. The contents of the water-soluble ions (such as Na+, K+, NH4+, and SO42–) of the 40000 h catalyst are higher than those of the fresh one. All these factors have a negative influence on the pore structure and active sites distribution over the 40000 h catalyst, thereby reducing its Hg0 oxidation efficiency.
