压缩应力下煤的孔隙结构和吸附性能的分子模拟,Energy & Fuels

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压缩应力下煤的孔隙结构和吸附性能的分子模拟
Energy & Fuels ( IF 5.2 ) Pub Date : 2023-01-13 , DOI: 10.1021/acs.energyfuels.2c03644
Hao Wang ₁ , Jianhua Xiang ₁ , Xiaopeng Deng ₂

Affiliation

压缩应力下煤大分子结构的变形可能影响孔隙结构和吸附性能。本研究采用Grand Canonical Monte Carlo和分子动力学方法研究压应力对煤孔隙结构和吸附性能的影响，探讨应力、应变、孔隙结构和吸附性能之间的耦合关系。构建了煤的大分子模型，并进行了单轴压缩模拟。压应力的增加使煤的孔隙体积、比表面积和连通性降低，孔径分布集中在尺寸较小的孔隙中。应力的增加导致煤对CH _{4的吸附性能出现不同程度的降低}和CO ₂，CH ₄的胁迫敏感性略强于CO ₂。不同应变下孔中吸附构型的结果表明，吸附性能的降低受孔体积和孔连通性的控制。CH ₄和CO _{2的吸附性能}煤中不同应变与孔隙体积和比表面积具有良好的线性关系；孔隙体积和比表面积越小，煤的吸附性能越弱。本研究阐明了压应力下应变响应对煤的孔隙结构和吸附特性的控制，为煤层气的吸附、解吸和扩散研究提供了指导。

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Molecular Simulation of the Pore Structure and Adsorption Properties of Coal under Compression Stress

The deformation of the macromolecular structure of coal under compression stress may affect the pore structure and adsorption properties. In this study, the Grand Canonical Monte Carlo and molecular dynamics methods were used to investigate the effects of compression stress on the pore structure and adsorption properties of coal, and the coupling relationships between stress, strain, pore structure, and adsorption properties were explored. A macromolecular model of coal was constructed, and uniaxial compression simulation was conducted. The increase of compression stress reduces the pore volume, specific surface area, and connectivity of coal and concentrates the pore size distribution in pores with smaller sizes. The increase of stress leads to a different degree of reduction in the adsorption performance of coal on CH₄ and CO₂, and the stress sensitivity of CH₄ is slightly stronger than that of CO₂. The results of adsorption configurations in the pores under different strains indicate that the reduction of adsorption properties is controlled by the pore volume and pore connectivity. The adsorption performance of CH₄ and CO₂ in coal at different strains has a good linear relationship with the volume and specific surface area of the pores; the smaller the volume and specific surface area of the pores, the weaker the adsorption performance of coal. This study clarifies the control of the strain response under compression stress on the pore structure and adsorption properties of coal and provides guidance for the study of adsorption, desorption, and diffusion of CBM.

更新日期：2023-01-13

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