CH_4和CO_2在油页岩中矿物质结构内部吸附的分子模拟

利用Materials Studio2017模拟软件构建了蒙脱石、高岭石、方解石和生石膏四种矿物质分子模型。采用巨正则蒙特卡洛(GCMC)方法和分子动力学(MD)方法对四种模型的吸附量和吸附热进行了模拟计算。研究表明,相同温度和压力条件下四种矿物质对CH_4和CO_2分子吸附量大小为:蒙脱石高岭石生石膏方解石;CH_4和CO_2分子的单组分吸附量随压力的增大而增大,两种气体吸附均符合Langmuir吸附规律;四种矿物质对CH_4和CO_2分子的等量吸附热均小于42 k J/mol,即为物理吸附;随着温度的升高,CH_4和CO_2分子的吸附量和吸附热均减小,且CH_4和CO_2分子的等量吸附热和等温吸附量之间呈良好的正相关。

A molecular simulation study on the adsorption of CH4 and CO2 on the mineral substances in oil shale

The models of montmorillonite, kaolinite, calcite and gypsum as the mineral substances in oil shale were built by using Materials Studio 2017 software; the adsorption of CH₄ and CO₂ on these mineral substances was then simulated by the GCMC and MD method. The results illustrated that the adsorption capacity of CH₄ and CO₂ on four mineral substances under the same temperature and pressure follows the order of montmorillonite > kaolinite > gypsum > calcite. The adsorption of single component CH₄ and CO₂ is in accordance with the Langmuir isotherm and the adsorption heats for both CH₄ and CO₂ on four mineral models all are less than 42 kJ/mol, suggesting that the adsorption belongs to physical category. With the increase of temperature, both the adsorption capacity and adsorption heat are reduced; there is a positive correlation between the adsorption heat and adsorption capacity for the CH₄ and CO₂ molecules.