Regenerable Cobalt Oxide Loaded Magnetosphere Catalyst from Fly Ash for Mercury Removal in Coal Combustion Flue Gas
2014
Yang, Jianping | Zhao, Yongchun | Zhang, Junying | Zheng, Chuguang
To remove Hg⁰ in coal combustion flue gas and eliminate secondary mercury pollution of the spent catalyst, a new regenerable magnetic catalyst based on cobalt oxide loaded magnetospheres from fly ash (Co–MF) was developed. The catalyst, with an optimal loading of 5.8% cobalt species, attained approximately 95% Hg⁰ removal efficiency at 150 °C under simulated flue gas atmosphere. O₂ could enhance the Hg⁰ removal activity of magnetospheres catalyst via the Mars-Maessen mechanism. SO₂ displayed an inhibitive effect on Hg⁰ removal capacity. NO with lower concentration could promote the Hg⁰ removal efficiency. However, when increasing the NO concentration to 300 ppm, a slightly inhibitive effect of NO was observed. In the presence of 10 ppm of HCl, greater than 95.5% Hg⁰ removal efficiency was attained, which was attributed to the formation of active chlorine species on the surface. H₂O presented a seriously inhibitive effect on Hg⁰ removal efficiency. Repeated oxidation–regeneration cycles demonstrated that the spent Co–MF catalyst could be regenerated effectively via thermally treated at 400 °C for 2 h.
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