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Roles of γ-Fe_2O_3 in fly ash for mercury removal: Results of density functional theory study

机译：γ-Fe_2O_3在粉煤灰中去除汞中的作用：密度泛函理论研究的结果

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摘要

First-principle calculations based on density function theory (DFT) are used to clarify the roles of γ-Fe_2O_3 in fly ash for removing mercury from coal-fired flue gases. In this study, the structure of key surface of γ-Fe_2O_3 is modeled and spin-polarized periodic boundary conditions with the partial relaxation of atom positions are employed. Binding energies of Hg on γ-Fe_2O_3 (001) perfect and defective surfaces are calculated for different adsorption sites and the potential adsorption sites are predicted. Additionally, electronic structure is examined to better understand the binding mechanism. It is found that mercury is preferably adsorbed on the bridge site of γ-Fe_2O_3 (001) perfect surface, with binding energy of -54.3 kJ/mol. The much stronger binding occurs at oxygen vacancy surface with binding energy of -134.6 kJ/mol. The calculations also show that the formation of hybridized orbital between Hg and Fe atom of γ-Fe_2O_3 (001) is responsible for the relatively strong interaction of mercury with the solid surface, which suggests that the presently described processes are all noncatalytic in nature. However, this is a reflection more of mercury's amalgamation ability.
机译：基于密度泛函理论（DFT）的第一性原理计算被用于阐明粉煤灰中γ-Fe_2O_3对去除燃煤烟气中汞的作用。本研究对γ-Fe_2O_3关键表面的结构进行了建模，并采用了原子位置部分松弛的自旋极化周期边界条件。计算了不同吸附位点上Hg在γ-Fe_2O_3（001）完美表面和缺陷表面上的结合能，并预测了潜在的吸附位点。此外，还检查了电子结构以更好地了解绑定机制。发现汞优选以-54.3kJ / mol的结合能吸附在γ-Fe_2O_3（001）完美表面的桥位上。在氧空位表面发生更强的结合，结合能为-134.6 kJ / mol。计算还表明，γ-Fe_2O_3（001）的Hg与Fe原子之间杂化轨道的形成是汞与固体表面相对较强的相互作用的原因，这表明目前描述的过程本质上都是非催化过程。但是，这更多地反映了汞的合并能力。

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  • 来源
    《Applied Surface Science》 |2010年第23期|P.6991-6996|共6页
  • 作者

    Pan Guo; Xin Guo; Chuguang Zheng;

  • 作者单位

    State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Luo Yu Lu, 1037, Wuhan 430074, China;

    rnState Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Luo Yu Lu, 1037, Wuhan 430074, China;

    rnState Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Luo Yu Lu, 1037, Wuhan 430074, China;

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  • 原文格式 PDF
  • 正文语种 eng
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  • 关键词

    mercury; γ-Fe_2O_3; density functional theory; amalgamation;

    机译：汞;γ-Fe_2O_3;密度泛函理论;合并;

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