Oxidation of elemental mercury by modified spent TiO2-based SCR-DeNO(x) catalysts in simulated coal-fired flue gas

摘要

In order to reduce the costs, the recycle of spent TiO2-based SCR-DeNO(x) catalysts were employed as a potential catalytic support material for elemental mercury (Hg-0) oxidation in simulated coal-fired flue gas. The catalytic mechanism for simultaneous removal of Hg-0 and NO was also investigated. The catalysts were characterized by Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) method. Results indicated that spent TiO2-based SCR-DeNO(x) catalyst supported Ce-Mn mixed oxides catalyst (CeMn/SCR1) was highly active for Hg-0 oxidation at low temperatures. The Ce1.00Mn/SCR1 performed the best catalytic activities, and approximately 92.80 % mercury oxidation efficiency was obtained at 150 A degrees C. The inhibition effect of NH3 on Hg-0 oxidation was confirmed in that NH3 consumed the surface oxygen. Moreover, H2O inhibited Hg-0 oxidation while SO2 had a promotional effect with the aid of O-2. The XPS results illustrated that the surface oxygen was responsible for Hg-0 oxidation and NO conversion. Besides, the Hg-0 oxidation and NO conversion were thought to be aided by synergistic effect between the manganese and cerium oxides.