甲烷在官能团化石墨中吸附的分子模拟

Molecular simulation for methane adsorption in surface functionalized graphite

页岩中干酪根结构简化为不同碳/氧比的石墨结构,利用分子模拟方法研究甲烷分子在不同碳/氧比石墨中赋存微观结构,并研究不同孔径和不同压力对甲烷在不同碳/氧比石墨中吸附行为的影响,在此基础上讨论碳/氧比变化对甲烷吸附行为的影响。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,或随着碳/氧比增加而下降,且甲烷平均等量吸附热小于42kJ/mol,说明甲烷在不同碳/氧比石墨中吸附属于物理吸附;不同碳/氧比石墨微孔中,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;在相同孔径中,甲烷吸附量随着碳/氧比增加而减小,甲烷分子在孔中吸附气量占比随着压力增大而呈下降趋势;相同压力下,甲烷分子在孔中吸附气量占比随着孔径增大而减小。

In this study,the structure of kerogen in shales was simplified as that of the graphite with different carbon to oxygen ratio（C/O）.Molecular simulation method is adopted to study the microstructure of methane in the graphite with different C/O and the influence of different aperture and pressure on methane absorption in the graphite with different C/O.On this basis,the influence of the varied C/O on methane adsorption is also discussed.The results prove that the average isosteric heats of absorption of methane,which is less than the 42 kJ/mol,decreases with the increasing of pore size or C/O,indicating that the methane adsorption in the graphite with different C/O is classified as physical adsorption.The methane adsorption capacity is increased with the increase of pore size in micro-pores of the graphite with different C/O,while decrease with the increase of pore size in meso-pores.Given the same pore size,the methane adsorption capacity is decreased with the increase of C/O and the proportion of adsorbed methane in the pores tends to decrease as the pressure increases.Given the same pressure,the proportion of adsorbed methane in the pores is decreased with the increase of the pore size.