煤表面分子对甲烷吸附力场研究

发布时间：2018-07-08 08:48

本文选题：密度泛函 + 吸附模型　；参考：《西安科技大学学报》2015年01期

【摘要】：采用密度泛函理论DFT方法,建立煤大分子骨架模型,并以范德华力作用半径为边界条件,构建煤大分子对CH_4分子吸附的量子动力学模型,在6-311G++基组上对煤大分子骨架模型和吸附模型结构进行优化,通过密立根电荷量分析了煤大分子表面的吸附空位,以及甲烷气体分子从游离态到吸附态的物理结构和特性变化。研究结果表明,煤表面分子和甲烷分子之间的吸附力场主要是静电场,甲烷分子在吸附过程中被极化,产生电偶极矩,C-H分子键长增大,吸附质和吸附剂之间的范德华力主要是诱导力和色散力以及甲烷分子被极化后的取向力,煤大分子表面的吸附空位可以通过煤大分子中各原子的密立根电荷量分析定量确定,通过模型结构优化发现,同一吸附空位可以对应多种甲烷分子吸附平衡结构,煤对甲烷分子的吸附为多分子层吸附。
[Abstract]:Based on density functional theory (DFT) method, the coal macromolecular skeleton model is established, and the quantum dynamics model for the adsorption of CH4 molecules by coal macromolecules is constructed using van der Waals force radius as the boundary condition. The structure of coal macromolecular skeleton model and adsorption model were optimized on 6-311G basis set. The adsorption vacancy on coal macromolecule surface and the physical structure and characteristics of methane gas molecule from free state to adsorbed state were analyzed by the charge quantity of Milliken. The results show that the adsorption force field between coal surface molecules and methane molecules is mainly electrostatic field, methane molecules are polarized during the adsorption process, resulting in the increase of C-H molecular bond length. The van der Waals force between adsorbents and adsorbents is mainly induced force, dispersion force and the orientation force of methane molecule after polarization. The adsorption vacancy on the surface of coal macromolecule can be quantitatively determined by the analysis of the atomic charge quantity of each atom in the coal macromolecule. Through the optimization of the model structure, it is found that the same adsorption vacancy can correspond to a variety of methane molecular adsorption equilibrium structures, and the adsorption of coal to methane molecule is multimolecular layer adsorption.
【作者单位】：西安科技大学理学院;
【分类号】：TD712

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