Methane adsorption on the surface of a model of shale: A density functional theory study
Methane adsorption on the surface of a model of shale: A density functional theory study
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DOI：
10.1016/j.apsusc.2016.06.033
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发表时间：
2016-11
影响因子：
6.7
通讯作者：
Yuanqiang Zhu;H. Su;Y. Jing;Jianchun Guo;Junlei Tang
中科院分区：
文献类型：
--
作者：
Yuanqiang Zhu;H. Su;Y. Jing;Jianchun Guo;Junlei Tang
作为页岩的模型，多环芳环的一部分被用来代表具有结构非均质性的干酪根表面。采用M06-2×泛函D3色散校正方法研究了甲烷在干酪根表面的吸附机理。系统地研究了干酪根表面9个稳定的吸附位和甲烷（CH 4）的吸附方向。从不同的方法得到的信息导致相同的结论，即甲烷更喜欢被吸附在直接在干酪根的碳原子上的网站，而不是在六元环的中心。甲烷与干酪根表面之间的相互作用是货车范德华相互作用。在M06-2×-D3/Jun-cc-pVDZ水平下，基组叠加误差（BSSE）校正的相互作用能约为14 kJ mol− 1。RDG散点图和RDG梯度等值面进一步说明甲烷与干酪根表面的相互作用属于货车范德华相互作用。弱相互作用表明甲烷在干酪根表面的吸附是物理吸附，且与干酪根表面的吸附位和甲烷的取向有关。这些结果对认识甲烷-页岩相互作用的微观机理和页岩气的开发利用具有重要意义。
As a model of shale, one part of polycyclic aromatic ring was used to represent the kerogen surface with the structural heterogeneity. The adsorption mechanisms of methane on the surface of the kerogen were investigated by M06-2× functional with D3 dispersion correction. Nine stable adsorption sites and the orientations of methane (CH4) on the surface of the kerogen were systematically considered. Information from different methods lead to the same conclusion that methane prefers to be adsorbed on the sites directly above the carbon atoms of the kerogen rather than above the center of the six-membered rings. The interactions between methane and the surface of the kerogen are the van der Waals interactions. The interaction energies with the basis set superposition error (BSSE) corrections are around 14 kJ mol−1at the M06-2×-D3/Jun-cc-pVDZ level. The RDG scatter graphs and the RDG gradient isosurface further illustrate that the interactions between methane and the surface of the kerogen belong to the van der Waals interactions. The weak interactions indicate that the adsorption of methane on the surface of the kerogen is physical adsorption and it slightly depends upon the adsorption sites on kerogen as well as the orientations of methane. These results are helpful for the understanding of the microcosmic mechanism of methane–shale interactions and for the exploitation of shale gas.