Mo/Fe3O4(111)表面对燃煤烟气汞吸附的密度泛函研究

A DFT study on the adsorption of various mercury species in the coal combustion flue gases on the Mo-doped Fe3O4(111)surface

利用CASTEP软件包采用密度泛函理论计算研究了过渡金属Mo掺杂Fe3O4(111)Fetet表面对Hg0、HgCl和HgCl2的吸附特征,分析了Mo掺杂前后Fe3O4(111)Fetet表面上不同汞物种的吸附形态。结果表明,Mo掺杂Fe3O4(111)Fetet表面对HgCl和HgCl2为化学吸附,而对Hg0的吸附为物理吸附;与纯净表面相比,HgCl在Mo原子掺杂表面上的吸附能提高了40%-66%。HgCl2在纯净Fe3O4(111)Fetet表面形成"M"形结构;而掺杂Mo原子后,由于Cl原子与Mo原子之间更强的相互作用,使得HgCl2发生了完全解离,两个Cl原子分别与Mo原子和Fe原子成键吸附在表面,Hg脱附。相关研究结果可为脱除燃煤烟气中的汞提供一定的理论指导。

The adsorption characteristics of Hg0,HgCl and HgCl2 on the Mo-doped Fe3O4(111)Fe tet surface were investigated by density functional theory(DFT)calculation with the CASTEP software package.The results indicate that both HgCl and HgCl 2 are chemically adsorbed on the Mo-doped Fe3O4(111)Fe tet surface,whereas Hg0 is bound to the surface by physisorption.The binding energies of HgCl on the Mo-doped Fe 3O 4(111)Fe tet surface is about 40%-66%higher than that on the pure Fe3O4(111)Fe tet surface.For the adsorption of HgCl 2 molecule on the pure Fe3O4(111)Fe tet surface,two Cl atoms interact with one Mo atom and one Fe atom,forming the"M"structure;in contrast,on the Mo-doped Fe3O4(111)Fe tet surface,the stronger interaction between Cl atom and Mo atom allows a complete dissociation of HgCl2 and release of Hg.The adsorption mechanism of mercury species on the Mo-doped Fe3O4(111)Fe tet surface revealed in this work may be helpful for the practical removal of mercury from coal-fired flue gases.