H_2O对SO_2在CaO表面上吸附的影响理论研究

采用密度泛函理论研究了H_2O对SO_2在CaO(001)表面上吸附的影响。结果表明,以四种形式(-H_2O、-H、-OH和-H-OH)存在的H_2O使SO_2在CaO表面上的吸附构型发生改变。SO_2在不同形式H_2O基团邻位吸附时,-H使S原子的p轨道态密度峰明显左移且吸附能比洁净表面大90 kJ/mol,其余基团表面吸附能无明显变化;SO_2吸附于-OH和-H-OH生成HSO_3基团,吸附能相比于洁净表面较小,可能作为暂态结构;SO_2吸附于-H_2O生成SO_3基团,H_2O断键生成的H基团起主要吸附作用,CaO表面上生成类似Ca(OH)_2的局部结构且吸附能比洁净表面大45 kJ/mol。

Influence of H2O on the adsorption of SO2 on CaO (001) surface: A DFT study

The influence of H₂O on the adsorption of SO₂ on CaO (001) surface was investigated by density functional theory (DFT). The results indicate that H₂O can have an effect on the adsorption geometries for SO₂ on the CaO (001) surface. When SO₂ is adsorbed to the CaO surface near a water group of different forms (viz., -H₂O, -H, -OH and -H & -OH), the H group makes the adsorption energy 90 kJ/mol higher with the sulfur p-orbital shifting downward, whereas other groups have little effect on the adsorption energy. When SO₂ is adsorbs to the -OH surface and -H & -OH surface, bisulfite-like structures are formed, with lower adsorption energies and tending to form more stable structures as intermediates. When SO₂ adsorbs to the -H₂O surface, bisulfite-like structure is formed and the H₂O group decomposes to Ca(OH)₂ like-structure on the CaO surface; the new H groups mainly bond the bisulfite and make adsorption energy 45 kJ/mol higher.