Influence of So3 on the Mnox/Tio2 Scr Catalyst for Elemental Mercury Removal and the Function of Fe Modification

Elemental mercury (Hg0) is a highly hazardous pollutant of coal combustion. The low-temperature SCR catalyst of MnOx/TiO2 can efficiently remove Hg0 in coal-burning flue gas. Considering its sulfur sensitivity, the effect of SO3 on the catalytic efficiency of MnOx/TiO2 and Fe modified MnOx/TiO2 for Hg0 removal was investigated comprehensively for the first time. Characterizations of Hg-TPD and XPS were conducted to explore the catalytic mechanisms of Hg0 removal processes under different conditions. Hg0 removal efficiency of MnOx/TiO2 was inhibited irreversibly from 92% to approximately 60% with the addition of 50 ppm SO3 at 150 ℃, which resulted from the transformation of Mn4+ and chemisorbed oxygen to MnSO4. The existence of H2O would intensify the inhibitory effect. The inhibition almost disappeared and even converted to promotion as the temperature increased to 250 ℃ and above. Fe modification on MnOx/TiO2 improved the Hg0 removal performance in the presence of SO3. The addition of SO3 caused only a slight inhibition of 1.9% on Hg0 removal efficiency of Fe modified MnOx/TiO2 in simulated coal-fired flue gas, and the efficiency maintained good stability during a 12 h experimental period. This work would be conducive to the future application of MnOx/TiO2 for synergistic Hg0 removal.
This research was supported financially by the National Natural Science Foundation of China (No. 52106169), the Natural Science Foundation of Shandong Province (No. ZR2021QE031), the China Postdoctoral Science Foundation (No. 2021M690097), the Foundation of State Key Laboratory of Coal Combustion (No. FSKLCCA2205), Taishan Scholars (No. ts201712003), the Postdoctoral Applied Research Project of Qingdao, and the Fundamental Research Funds of Shandong University (No. 2020GN008)