School of Emergency Management and Safety Engineering, China University of Mining and Technology (Beijing), No. ding 11 College Road, Haidian District, Beijing, 100083, China.
Environ Sci Pollut Res Int. 2021 May;28(20):25368-25381. doi: 10.1007/s11356-021-12399-7. Epub 2021 Jan 17.
In view of the frequent occurrence of gas accidents in coal mines, the mechanism of oxygen-containing functional groups (OCFGs) in Danhou lignite adsorbing gas was studied by experiment and simulation. Elemental analysis, X-ray photoelectron spectroscopy (XPS), solid-state C nuclear magnetic resonance spectroscopy (C-NMR), and adsorption experiment of CH were applied to establish the macromolecular model of Danhou lignite. Then, molecular mechanics (MM) and molecular dynamics (MD) were utilized to optimize the coal macromolecular model, and the density of coal was determined via adding periodic boundary conditions. The mechanism of gas adsorption by OCFGs was studied by grand canonical Monte Carlo (GCMC) and density functional theory (DFT). The results showed that the aromatic structures mostly exist in the form of pyrenes; the structure of aliphatic carbons are mostly methylene and methine groups; the alkanes are mostly long chains; oxygen atoms are mainly in the form of hydroxyl groups and ether groups; nitrogen atoms are mainly in the form of pyridines; and the density of Danhou lignite is 1.25 g/cm. The isotherm adsorption curve and Langmuir adsorption curve have a good fit, a single coal molecule reaches saturation after absorbing four CH molecules, and the error between experiment and simulation is small. The results of DFT calculation showed that the adsorption of CH by OCFGs is affected by the adsorption positions and adsorption directions. Due to CH molecules are affected by different electrostatic forces, the adsorption capacities of OCFGs are different, and the order is carbonyl groups > ether bonds > hydroxyl groups > carboxyl groups. The results can be used for reference in the prevention and control of coal and gas outburst.
针对煤矿瓦斯事故频发的问题，采用实验和模拟相结合的方法研究了含氧官能团（OCFGs）在褐煤中吸附气体的机理。利用元素分析、X 射线光电子能谱（XPS）、固态 C 核磁共振谱（C-NMR）和 CH 吸附实验建立了褐煤大分子模型。然后，采用分子力学（MM）和分子动力学（MD）对煤大分子模型进行优化，并通过添加周期性边界条件确定煤的密度。利用巨正则蒙特卡罗（GCMC）和密度泛函理论（DFT）研究了 OCFGs 的气体吸附机理。结果表明，褐煤中的芳香结构主要以并五苯的形式存在；脂肪碳结构主要为亚甲基和次甲基；烷烃主要为长链；氧原子主要以羟基和醚基的形式存在；氮原子主要以吡啶的形式存在；褐煤的密度为 1.25 g/cm³。等温吸附曲线和 Langmuir 吸附曲线拟合良好，单个煤分子在吸附四个 CH 分子后达到饱和，实验与模拟的误差较小。DFT 计算结果表明，OCFGs 对 CH 的吸附受吸附位置和吸附方向的影响。由于 CH 分子受到不同的静电力作用，OCFGs 的吸附容量不同，其顺序为羰基>醚键>羟基>羧基。研究结果可为煤与瓦斯突出的防治提供参考。
