甲烷在黏土矿物狭缝孔中吸附的分子模拟研究

发布时间：2018-06-16 16:54

本文选题：黏土矿物 + 甲烷　；参考：《煤炭学报》2017年04期

【摘要】：利用巨正则蒙特卡罗模拟方法和分子动力学方法研究甲烷分子在4类黏土矿物(蒙脱石、高岭石、伊利石和绿泥石)中赋存微观结构和微观吸附机理,并研究不同孔径和不同压力对甲烷在4类黏土矿物中吸附行为的影响。研究结果表明:甲烷的平均等量吸附热随着孔径增大而下降,且小于42 k J/mol,证明甲烷在黏土矿物中的吸附属于物理吸附;甲烷分子受到黏土矿物孔壁面势能作用影响,在孔壁面附近区域聚集从而形成吸附层,其为吸附相,而远离孔壁区域,受到孔壁面势能较弱或未受到孔壁面势能作用影响,甲烷分子分散于孔中,其为游离相;甲烷分子在不同类型黏土矿物不同尺度的孔隙中赋存状态存在差异;黏土矿物微孔中,甲烷吸附量随着孔径增大而增大,而中孔中,甲烷吸附量随着孔径增大而减小;从微观角度来看相同孔径中,不同类型黏土矿物对甲烷近似有相同的吸附能力,但是宏观角度来看不同类型黏土矿物样品对甲烷的吸附能力差异较大,说明不同类型黏土矿物样品对甲烷吸附能力主要通过比表面积因素来影响;甲烷分子在孔中吸附气量所占比例随着压力增大或孔径增大而呈下降趋势。
[Abstract]:The microstructure and microadsorption mechanism of methane molecules in four kinds of clay minerals (montmorillonite, kaolinite, Illite and chlorite) were studied by means of grand regular Monte Carlo simulation and molecular dynamics. The effects of different pore sizes and pressures on the adsorption behavior of methane in four kinds of clay minerals were studied. The results show that the average adsorption heat of methane decreases with the increase of pore size, and is less than 42 k / mol, which indicates that the adsorption of methane in clay minerals belongs to physical adsorption, and methane molecules are affected by the potential energy of the pore wall of clay minerals. The adsorption layer is formed in the area near the pore wall, which is the adsorption phase, but far away from the pore wall, it is affected by the weak or unaffected potential energy of the pore wall, and methane molecules are dispersed in the pore, which is the free phase. The adsorption capacity of methane in the micropores of clay minerals increases with the increase of pore size, but decreases with the increase of pore size in mesoporous pores. From the microscopic point of view, different types of clay minerals have approximately the same adsorption capacity for methane in the same pore size, but from the macro point of view, the adsorption capacity of different types of clay minerals for methane is quite different. The results show that the adsorption capacity of different clay minerals on methane is mainly affected by the specific surface area factor, and the proportion of methane molecule adsorbed gas in the pore decreases with the increase of pressure or pore size.
【作者单位】：西南石油大学油气藏地质及开发工程国家重点实验室;
【基金】：国家自然科学基金青年基金资助项目(41602155)
【分类号】：P618.13

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