Sun Haoyang, Zhao Hui, Qi Na, Li Ying
Key Laboratory of Colloid and Interface Chemistry of State Education Ministry, Shandong University, 27 South of Shanda Road, 250100 Jinan, P. R. China.
ACS Omega. 2017 Nov 7;2(11):7600-7608. doi: 10.1021/acsomega.7b01185. eCollection 2017 Nov 30.
Molecular dynamics simulation studies were employed to investigate the microscopic behaviors of CH and CO molecules in slit-nanopores (SNPs) with various surfaces and different compositions. Three kinds of SNPs were constructed by a pair-wise combination of graphene, silica, and the calcite surface. The grand canonical Monte Carlo and molecular dynamics simulation methods were used to investigate the adsorption and self-diffusion of the gases in the nanopores. It is found that in all three cases, the CH molecules prefer to adsorb onto the graphene surface, whereas the CO molecules prefer to adsorb onto the calcite surface. The adsorption intensity of gases adsorbed onto various surfaces, the adsorption distances, along with the details of adsorption orientations of CH and CO molecules on various surfaces are calculated. The surface characteristics, such as surface roughness and charge distribution, are analyzed to help understand the microscopic adsorption behaviors of the gases on the specific surface. It was found that competitive adsorptions of CO over CH broadly occurred, especially in the SNPs containing calcite, because of the strong adsorption interactions between the CO molecules and the calcite surface. This work provides the microbehaviors of CH and CO in SNPs with various surfaces in different compositions to provide useful guidance for better understanding about the microstate of gases in complex nanoporous shale formation and to give out useful guidance for enhancing shale gas recovery by injecting CO.
采用分子动力学模拟研究，以探究具有不同表面和组成的狭缝纳米孔（SNP）中CH和CO分子的微观行为。通过石墨烯、二氧化硅和方解石表面的两两组合构建了三种SNP。运用巨正则蒙特卡罗和分子动力学模拟方法，研究了气体在纳米孔中的吸附和自扩散。研究发现，在所有三种情况下，CH分子更倾向于吸附在石墨烯表面，而CO分子更倾向于吸附在方解石表面。计算了吸附在各种表面上的气体的吸附强度、吸附距离以及CH和CO分子在各种表面上的吸附取向细节。分析了表面粗糙度和电荷分布等表面特性，以帮助理解气体在特定表面上的微观吸附行为。研究发现，CO对CH的竞争性吸附广泛存在，尤其是在含有方解石的SNP中，这是由于CO分子与方解石表面之间存在强烈的吸附相互作用。这项工作提供了不同组成的具有各种表面的SNP中CH和CO的微观行为，为更好地理解复杂纳米多孔页岩地层中气体的微观状态提供了有用的指导，并为通过注入CO提高页岩气采收率提供了有用的指导。
