煤分子结构中不同气体的吸附—扩散微观机理研究  

Study on microscopic mechanism of adsorption-diffusion of different gases in coal molecular structure

作　　者：上官科峰 万成 完颜晓亮 刘宗林 Shangguan Kefeng;Wan Cheng;Wanyan Xiaoliang;Liu Zonglin(Huating Coal Industry Group Co.,Ltd.,Huating 744100,China;Huating Coal Mine,Huating Coal Industry Group Co.,Ltd.,Huating 744100,China)

机构地区：[1]华亭煤业集团有限责任公司,甘肃华亭744100 [2]华亭煤业集团有限责任公司华亭煤矿,甘肃华亭744100

出　　处：《能源与环保》2024年第11期42-48,共7页CHINA ENERGY AND ENVIRONMENTAL PROTECTION

基　　金：中国华能科技研发项目(HNKJ21-H56-11)。

摘　　要：为探究CO_(2)/CH_(4)/N_(2)气体在煤大分子结构中吸附—扩散效应的差异性和微观机理,基于鄂尔多斯上湾煤矿褐煤大分子结构模型,采用密度泛函理论方法(DFT)、蒙特卡洛方法(GCMC)和分子动力学方法(MD)对煤分子模型的静电势分布特征、最高占据轨道(HOMO)和最低空轨道(LUMO)能级、孔隙结构分布特征和吸附—扩散效应进行模拟研究。结果表明,褐煤分子结构中O与N原子周围呈负电势,H原子周围呈正电势;HOMO值为-0.155 273 eV,LUMO值为-0.154 189 eV,煤晶胞模型中CO_(2)分子所能进入的孔隙空间最大,N_(2)次之,CH_(4)最小;3种气体的吸附量、吸附热和相互作用能从大到小顺序为CO_(2)>CH_(4)>N_(2),并且随温度的升高而降低;CO_(2)扩散系数最大,N_(2)次之,CH_(4)最小,高温有利于气体的扩散行为。To explore the difference and microscopic mechanism of adsorption-diffusion effect of CO_(2)/CH_(4)/N_(2) gas in coal macromolecular structure,based on the macromolecular structure model of lignite in Shangwan Coal Mine,Ordos,the electrostatic potential distribution characteristics,highest occupied orbital(HOMO)and lowest vacant orbital(LUMO)energy levels and pore structure distribution characteristics of coal molecular model were studied by Density Functional Theory(DFT),Monte Carlo Method(GCMC)and Molecular Dynamics Method(MD).The results show that there is a negative potential around O and N atom and a positive potential around H atom in the molecular structure of lignite.HOMO value is-0.155273 eV,LUMO value is-0.154189 eV.In the coal crystal cell model,CO_(2) molecules can enter the largest pore space,followed by N_(2) and and CH_(4) is the smallest.The order of adsorption capacity,adsorption heat and interaction energy of the three gases from small to large is CO_(2)>CH_(4)>N_(2),and they decrease with the increase of temperature.The diffusion coefficient of CO_(2) is the largest,followed by N_(2),and CH_(4) is the smallest.High temperature is beneficial to the gas diffusion behavior.

关 键 词：静电势分布 HOMO/LUMO轨道能级 煤大分子模型 孔隙结构 吸附—扩散 

分 类 号：TD752.2[矿业工程—矿井通风与安全]