CO在烟煤中吸附与扩散的分子模拟研究*

为揭示CO在烟煤中的微观吸附和扩散机理，利用Wiser烟煤分子模型，通过巨正则蒙特卡洛（GCMC）和分子动力学方法，研究5种不同温度（293.15,303.15,313.15,323.15,333.15 K）下，压力为0.1～3.0 MPa时CO吸附量、吸附热的变化，采用能量分布分析CO在烟煤中的吸附行为，利用扩散系数和扩散活化能研究CO在烟煤中的扩散特性。研究结果表明:CO在烟煤分子中的模拟结果符合朗格缪尔（Langmuir）吸附规律，随着温度的升高，Langmuir参数a和b减小，CO在烟煤分子中饱和吸附量和吸附能力降低。温度越高，烟煤分子的等量吸附热越低，烟煤分子吸附CO分子的平均等量吸附热为21.20～23.11 kJ/mol，小于42 kJ/mol，属于物理吸附；随着压力的升高，CO分子由能量较高的优势吸附位点逐渐向相对较弱的吸附位点移动；在模拟的温度和压力条件下，CO在烟煤分子模型中的扩散系数随温度和压力的升高而增加，扩散活化能随压力的升高而减小。研究结果为揭示CO在烟煤分子中微观吸附与扩散规律，准确预测采空区封闭火区煤自燃情况具有重要意义。

Molecular simulation study on adsorption and diffusion of CO in bituminous coal

In order to reveal the microscopic adsorption and diffusion mechanism of CO in bituminous coal,the change of CO adsorption amount and adsorption heat under 5 different temperatures (293.15,303.15,313.15,323.15,333.15 K) and the pressure of 0.1~3.0 MPa was study through the Grand Canonical Monte Carlo method (GCMC) and molecular dynamics methods by using the Wiser bituminous coal molecular model.The adsorption behavior of CO in bituminous coal was analyzed by using the energy distribution,and the diffusion characteristics of CO in bituminous coal were studied by using the diffusion coefficient and activation energy of diffusion.The results showed that the simulation results of CO in bituminous coal molecules conformed to the Langmuir adsorption law.With the increase of temperature,the Langmuir parameters a and b decreased,and the saturated adsorption amount and adsorption capacity of CO in bituminous coal molecules decreased.The higher the temperature,the lower the isosteric heat of adsorption of bituminous coal molecules.The average isosteric heat of adsorption of CO molecules by bituminous coal molecules was 21.20~23.11 kJ/mol,which was less than 42 kJ/mol and belonged to physical adsorption.With the increase of pressure,the CO molecules moved from the dominant adsorption site with higher energy to the relatively weak adsorption site.Under the conditions of simulated temperature and pressure,the diffusion coefficient of CO in bituminous coal molecular model increased with the increase of temperature and pressure,and the diffusion activation energy decreased with the increase of pressure.This conclusion is of great significance for revealing the microscopic adsorption and diffusion law of CO in bituminous coal molecules and accurately predicting the spontaneous combustion of coal in the closed fire area of goaf.