Wang Kai, Zhang Bin, Kang Tianhe
College of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
Key Laboratory of In-Situ Property-Improving Mining of the Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China.
Molecules. 2020 Feb 24;25(4):1001. doi: 10.3390/molecules25041001.
Because kaolinite includes a large range of defect elements, the effects of Mg, Fe(II), and Al doping on the CH adsorption and diffusion on the surface of Na-kaolinite (001) were investigated by molecular simulations. The simulation results illustrate that ion doping can significantly reduce the amount of CH adsorbed by kaolinite, but the type of doped ions has little effect on the amount of adsorption. The specific surface area of kaolinite and the interaction energy between CH and the kaolinite's surface are two key factors that can determine CH adsorption capacity. The first peak value of the radial distribution functions (RDFs) between CH and the pure kaolinite is larger than that between Mg-, Fe(II)-, and Al-doped kaolinite, which indicates that ion doping can reduce the strength of the interactions between CH and the kaolinite's surface. Besides hydrogen and oxygen atoms, interlayer sodium ions are also strong adsorption sites for CH and lead to a weakened interaction between CH and the kaolinite's surface, as well as a decrease in CH adsorption. Contrary to the adsorption results, ion doping facilitates the diffusion of CH, which is beneficial for actual shale gas extraction.
由于高岭石包含多种缺陷元素，通过分子模拟研究了Mg、Fe(II)和Al掺杂对CH在钠基高岭石(001)表面吸附和扩散的影响。模拟结果表明，离子掺杂可显著降低高岭石吸附CH的量，但掺杂离子类型对吸附量影响较小。高岭石的比表面积以及CH与高岭石表面之间的相互作用能是决定CH吸附能力的两个关键因素。CH与纯高岭石之间的径向分布函数(RDFs)的第一个峰值大于Mg、Fe(II)和Al掺杂高岭石之间的峰值，这表明离子掺杂可降低CH与高岭石表面之间的相互作用强度。除了氢原子和氧原子外，层间钠离子也是CH的强吸附位点，导致CH与高岭石表面之间的相互作用减弱，以及CH吸附量降低。与吸附结果相反，离子掺杂促进了CH的扩散，这有利于实际页岩气开采。
