Hg^0和SO_2在MnO_x/TiO_2表面吸附的量子化学研究

Quantum Chemistry Study of Hg^0 and SO_2 Adsorption on MnO_x/TiO_2 Surface

以Hg^0在锰基催化剂表面的吸附情况为基础,运用周期性密度泛函理论研究了Hg^0在纯TiO_2、MnO_x/TiO_2表面及SO2在MnO_x/TiO_2表面、Hg^0和SO2在MnO_x/TiO_2吸附剂表面的吸附机制。采用密度泛函理论的GGA-PBE计算方法,分别对各结构进行几何优化、能量计算、比较键长并分析吸附能大小。结果表明,Hg^0在TiO_2(001)表面的吸附能普遍较小,Hg^0与基底并未发生强的相互作用。在锰基表面上,Mn能使Hg^0的离子性增强。而SO2在MnO_x/TiO_2(001)表面吸附位较多且复杂,通过计算可以确定出能量最低的结构。当Hg、SO2同时放入锰基表面时,发现MnO_x/TiO_2(001)表面SO2的存在对Hg^0的吸附存在竞争关系。

Based on the adsorption of Hg0 on the manganese based catalyst surface, the adsorption mechanism of mercury （Hg0） from the flue gas was theoretically discussed with the method of density functional theory （DFT）, including the adsorption mechanism of Hg0 on the surface of pure TiO2 , MnOx/TiO2, Hg0 and SO2 on the surface of MnOx/TiO2. For each structure, the geometry optimization, the energy calculation, the bond length and the size of adsorption energy were calculated using density functional theory calculation method of the GGA-PBE. The results indicate that the adsorption energy of Hg0 on the surface of TiO2 （001） is generally small, so Hg0 does not have strong interaction with the substrate. On the surface of Mn base, Mn can enhance the ionic nature of mercury. The adsorption position of SO2 on MnOx/TiO2 （001） surface is complex, and the structure with the lowest energy can be determined by calculation. When Hg and SO2 are simultaneously placed on the surface of Mn base, it is found that SO2 and Hg0 was competitive on the MnOx/TiO2 （001） surface.