Oxidation of elemental mercury by modified spent TiO2-based SCR-DeNOx catalysts in simulated coal-fired flue gas
2016
Zhao, Lingkui | Li, Caiting | Zhang, Xunan | Zeng, Guangming | Zhang, Jie | Xie, Yin’e
In order to reduce the costs, the recycle of spent TiO₂-based SCR-DeNOₓ catalysts were employed as a potential catalytic support material for elemental mercury (Hg⁰) oxidation in simulated coal-fired flue gas. The catalytic mechanism for simultaneous removal of Hg⁰ 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-DeNOₓ catalyst supported Ce-Mn mixed oxides catalyst (CeMn/SCR₁) was highly active for Hg⁰ oxidation at low temperatures. The Ce₁.₀₀Mn/SCR₁ performed the best catalytic activities, and approximately 92.80 % mercury oxidation efficiency was obtained at 150 °C. The inhibition effect of NH₃ on Hg⁰ oxidation was confirmed in that NH₃ consumed the surface oxygen. Moreover, H₂O inhibited Hg⁰ oxidation while SO₂ had a promotional effect with the aid of O₂. The XPS results illustrated that the surface oxygen was responsible for Hg⁰ oxidation and NO conversion. Besides, the Hg⁰ oxidation and NO conversion were thought to be aided by synergistic effect between the manganese and cerium oxides.
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