Mercury Adsorption and Oxidation Performance of an Iron-Based Oxygen Carrier during Coal Chemical Looping Process
2024
Guochao Hu | Shuju Zhao | Minggang Gao | Yongzhuo Liu
During chemical looping combustion (CLC) and chemical looping gasification (CLG) of coal, the release, migration, and speciation of mercury in coal are significantly influenced by oxygen-carrier materials: however, the underlying mechanism remains inadequately addressed. In this work, the effect of a typical iron-based oxygen carrier on the release behavior of mercury from a bituminous coal and a lignite was investigated based on the Ontario-Hydro method. It is found that the effect of the iron-based oxygen carrier is attributed to three aspects: the enhanced release rate of mercury from coal, the adsorption of the released mercury, and the oxidization of gaseous Hg0 into Hg2+. With the increasing temperature, the adsorbance of mercury by the iron-based oxygen carrier decreases, while the oxidation of mercury enhances. Even at 900 °:C, the adsorbance of mercury by the oxygen carrier remained at 0.1687 g/g, with a relative content of Hg2+ at 22.55%. Additionally, it was observed that iron-based oxygen carriers can physically absorb both Hg0 and Hg2+, while chemisorption refers to complex-compound formation between the iron-based oxygen carrier and mercury.
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