Adsorption and oxidation of elemental mercury from coal-fired flue gas over activated coke loaded with Mn–Ni oxides.

A series of Mn–Ni/AC (AC, activated coke) catalysts were synthesized by the impregnation method for the removal of elemental mercury (Hg⁰) from simulated flue gas. The samples were characterized by BET, ICP-OES, SEM, XRD, XPS, H₂-TPR, FT-IR, and TGA. Mn₆Ni_0.75/AC exhibited optimal removal efficiency of 96.6% in the condition of 6% O₂ and balanced in N₂ at 150 °C. The experimental results showed that both O₂ and NO facilitated Hg⁰ removal. SO₂ could restrain the Hg⁰ removal in the absence of O₂, while the inhibitory effect of SO₂ was weakened with the aid of 6% O₂. In addition, H₂O exhibited a slightly negative influence on Hg⁰ removal. The characterization of the samples indicated that Mn₆Ni_0.75/AC possessed larger specific surface area, higher dispersion of metal oxides, and stronger redox ability. In the meantime, the results of XPS and FT-IR demonstrated that the lattice oxygen and chemisorbed oxygen made contributions to Hg⁰ removal and the consumed oxygen could be compensated by the redox cycle of metal oxides and gas-phase O₂. Meanwhile, the mechanisms of Hg⁰ removal were proposed based on the above studies. [ABSTRACT FROM AUTHOR]