Photocatalytic removal of elemental mercury via Ce-doped TiO2 catalyst coupling with a novel optical fiber monolith reactor

Xin, Feng; Ma, Siming; Yang, Jianping; Zhao, Yongchun; Zhang, Junying; Zheng, Chuguang

Photocatalytic removal of elemental mercury via Ce-doped TiO2 catalyst coupling with a novel optical fiber monolith reactor

2020

Reduction of mercury emission from coal combustion is a serious task for public health and environmental societies. Herein, Ce-doped TiO₂ (Ce/TiO₂) catalyst coupling with a novel optical fiber monolith reactor was applied to efficiently remove elemental mercury (Hg⁰) from coal-fired flue gas. Under the optimal operation condition (i.e., 1.5 mW/cm² UV light, 90 °C), above 95% of Hg⁰ removal efficiency was attained over the optical fiber monolith reactor coating with 3.40 g/m² Ce/TiO₂ catalyst. The effects of flue gas compositions on Hg⁰ removal performance were clarified systematically. Gaseous O₂ replenished the surface oxygen, hence maintaining the production of free radicals and promoting the removal of Hg⁰. SO₂, HCl, and NO inhibited Hg⁰ removal in the absence of O₂ due to the competitive adsorption and consumption of free radicals. However, SO₂ and HCl significantly enhanced Hg⁰ removal with the participation of O₂, while NO exhibited obviously inhibitory effect even with the assistance of O₂. H₂O also decreased the Hg⁰ oxidation capacity owing to the competitive adsorption and reduction of HgO. The optical fiber monolith reactor exhibited much superior Hg⁰ removal capacity than the powder reactor. Utilization of Ce/TiO₂ catalyst coupling with an optical fiber monolith reactor provides a cost-effective method for removing Hg⁰ from coal-fired flue gas.

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