中阶构造煤等温吸附/解吸特征及机理

选择四个不同变形程度的中阶煤样品作为研究对象,通过开展煤样的等温CH4吸附/解吸实验、X射线衍射(XRD)和傅里叶变换红外光谱(FT-IR)测试分析,研究了构造煤等温吸附/解吸性随煤变形程度的演化特征及其地球化学机理.结果表明,构造煤等温CH4吸附和解吸曲线随压力升高均呈现先快速增大后逐渐稳定的变化趋势,符合I型等温线...

Isothermal Adsorption/Desorption Characteristics,and Mechanism of Tectonically Deformed Medium-rank Coals

Four medium-rank coal samples with different degrees of tectonic deformation were studied to determine their isothermal adsorption/desorption evolution and geochemical mechanisms in isothermal CH₄ adsorption/desorption experiments， X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FT-IR） tests. It was found that their isothermal CH₄ adsorption and desorption curves showed a trend of initial rapid increase， gradually stabilizing with increasing pressure. This is consistent with the characteristics of a type I isotherm and the Langmuir model. With increasing coal deformation， the Langmuir volume had an increasing trend， and the degree of adsorption/desorption hysteresis decreased steadily. With increasing deformation， the dimension of the aromatic layer network gradually decreased and the unit extendability gradually increased. The unit stacking degree and the number of stacking layers changed in stages during deformation of the coal. The stress sensitivity of the coal crystal nucleus was stronger in the transverse direction than in the longitudinal direction， and was therefore affected more obviously by structural deformation. At the same time， with increasing deformation， the aromatic C=C skeleton clearly increased. The degree of condensation of the aromatic ring was higher than in the initial structure of the coal， while some aliphatic structures and the C=O structure steadily decreased. With increasing deformation， the rearrangement of aromatic structure， the degree of orientation of the macromolecular structure， and the degree of ordering all increased. The increase in short-range ordering of the coal crystal nucleus helps to improve the adsorption force of coal to CH₄ molecules， and the structural stress mainly affects adsorptive capacity by changing the side chains of the macromolecular structure and oxygen-containing functional groups.