CO_2在沸石咪唑酯骨架材料中的吸附机理研究

Adsorption Mechanism of CO_2 in Zeolitic Imidazolate Frameworks

沸石咪唑脂骨架材料(ZIFs)是一种新型的温室气体CO_2吸附材料。本文采用密度泛函理论计算CO_2在ZIF-68两种不同类型链(nIM和bIM)上的吸附能,计算中选用GGA/PW91泛函。计算结果表明CO_2分子在nIM链上和bIM链上的吸附存在明显的差异。在bIM链上,由于弱的C-H键的存在导致吸附过程中链的几何形状容易发生变形,从而得到较大的吸附能。吸附过程中CO_2分子的键角均有变化,在硝基官能团附近发生吸附时由于硝基的极化作用导致CO_2分子键角变化较其它吸附位变化明显。CO_2分子在nIM和bIM链上的吸附主要以物理吸附为主,范德华力是主要的相互作用力。

Zeolitic imidazolate frameworks（MOFs） are a new class of porous materials,which have been extensively used to capture CO_2 from flue gas.Density functional theory（DFT） has been used to calculate the adsorption energies of CO_2 on two different types of linkers（nIM and bIM linker） of ZIF-68.GGA/PW91 was used in this work.The results show that the adsorption behaviors of CO_2 on nIM and bIM linker are quite different.Compared to nIM linker,the relative higher adsorption energies obtained on bIM linker is due to the weak C-H bond which is easy to be distorted in geometry during the adsorption procedure.The bond angle of CO_2 is changed,especially around the area of nitro group because of the polarizing effect.The adsorption of CO_2 on bIM and nIM linker belongs to physisorption and the main interaction force is van der Waals force.