Study on microscopic mechanism of adsorption-diffusion of different gases in coal molecular structure
To explore the difference and microscopic mechanism of adsorption-diffusion effect of CO2/CH4/N2 gas in coal macromolecu-lar structure,based on the macromolecular structure model of lignite in Shangwan Coal Mine,Ordos,the electrostatic potential distribu-tion 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-0.155 273 eV,LUMO value is-0.154 189 eV.In the coal crystal cell model,CO2 molecules can enter the largest pore space,followed by N2 and and CH4 is the smallest.The order of adsorption capacity,adsorption heat and interaction energy of the three gases from small to large is CO2＞CH4＞N2,and they decrease with the increase of tempera-ture.The diffusion coefficient of CO2 is the largest,followed by N2,and CH4 is the smallest.High temperature is beneficial to the gas dif-fusion behavior.
electrostatic potential differenceHOMO/LUMO orbital energy levelcoal macromolecular modelpore structureadsorption-diffusion
万方数据
维普
