Hg在Pd掺杂的CeO_2表面吸附和脱除

基于密度泛函理论对Hg在纯CeO_2表面的吸附机理进行了理论计算,采用p(3×3)的二维超晶胞模型计算了CeO_23个不同表面上不同位点对汞的吸附能,计算结果表明,Hg在纯CeO_2表面吸附能力较弱,为物理吸附,Hg原子与CeO_2未形成有效化学键。为了进一步研究Hg在CeO_2表面的吸附机理,计算了Hg在Pd掺杂的CeO_2(Pd-CeO_2)表面的吸附机理,结果表明,Hg在Pd-CeO_2表面吸附能较强,为化学吸附,Hg原子与Pd-CeO_2之间形成有效的化学键,说明Pd的掺杂有利于提高CeO_2对汞的吸附能力。为了量化纯CeO_2和Pd-CeO_2的汞脱除效率,对Hg在纯CeO_2和Pd-CeO_2表面的脱除进行了实验研究。实验结果表明,纯CeO_2对汞的脱除效率较低,贵金属Pd的掺杂能够有效提高CeO_2的汞脱除效率,与理论计算的结果相符。

Adsorption and Removal of Hg on Pd Doped CeO2 Surfaces

The adsorption mechanism of Hg on pure CeO₂ surface was studied by the density functional theory. The adsorption energy of Hg on different surfaces and different sites of CeO₂ was calculated by two-dimensional supercell model of p(3×3). The results show that the adsorption capacity of Hg on pure CeO₂ is weak, which is a physical adsorption, and the Hg atom and CeO₂ do not form effective chemical bonds. In order to further study the adsorption mechanism of Hg on CeO₂ related surface, the adsorption mechanism of Hg on Pd doped CeO₂(Pd-CeO₂) surface was also studied. The results show that the adsorption capacity of Hg on Pd-CeO₂ is strong, which is a chemical adsorption, and the Hg atom and Pd-CeO₂ form effective chemical bonds. The adsorption capacity of Hg on CeO₂ surface is enhanced due to the doping of Pd. In order to further quantify the adsorption efficiency of Hg on the surface of pure CeO₂ and Pd-CeO₂, the experimental study has been carried on. The experimental results show that the adsorption efficiency of Hg on pure CeO₂ is low, and doping of Pd can effectively improve the adsorption efficiency of CeO₂, which are consistent with the results of theoretical calculation.