小分子有机物对CH4和CO2吸附动力学行为的影响研究

Study on the ramifications of small molecule organic matter within the kinetic behavior of CH4 and CO2 adsorption

  • 摘要: 煤的复杂孔隙结构和有机质组成显著影响瓦斯的储运特性,但目前针对可溶性有机质的作用机制仍缺乏深入研究。以四氢呋喃-2-醇(C4H8O2)为代表,通过量子化学模拟探讨小分子有机物对煤吸附CH4和CO2的影响,并计算确定了单个分子的静态电位,详细分析了吸附过程的吸附热、均方位移和径向分布函数以及吸附能量分布。结果表明:煤对CO2的吸附能力总是高于CH4;小分子有机物显著降低了煤的气体吸附量和吸附热,减弱杂原子与吸附质分子的相互作用,并且对CO2吸附影响较大,从而大幅度减弱CO2与煤分子之间的相互作用,以及CO2对甲烷的驱替作用;在6 MPa时,煤对CO2吸附影响最小。研究结果有助于深入理解煤层甲烷的赋存机理,为优化预抽瓦斯技术提供理论支撑,助力煤矿安全与高效生产。

     

    Abstract: The complex pore structure and organic matter composition of coal significantly affect the storage and transportation characteristics of gas, and the role of soluble organic matter is still lacking in in-depth research. This study, represented by tetrahydrofuran-2-ol (C4H8O2), explores the effect of small molecule organic compounds on coal adsorption of CH4 and CO2 through quantum chemical simulations. The static potential of a single molecule was determined through quantum chemistry calculations. Detailed analysis was conducted on the adsorption heat, mean square displacement, radial distribution function, and adsorption energy distribution during the adsorption process. The results indicate that the excessive adsorption capacity of coal for CO2 is always higher than that for CH4. Organic small molecules significantly reduce the gas adsorption capacity and adsorption heat of coal, weaken the interaction between heteroatoms and adsorbate molecules, and have a significant impact on CO2 adsorption, thereby significantly reducing the interaction between CO2 and coal molecules and weakening the displacement effect of CO2 on methane. At 6 MPa, its impact on CO2 adsorption is minimal. The results of this study contribute to a better understanding of the occurrence mechanism of coalbed methane, providing theoretical support for optimizing pre extraction gas technology and assisting in coal mine safety and efficient production.

     

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