Abstract: To reveal the adsorption thermodynamic mechanism of CO₂ and CH₄ on coal,isothermal adsorption experiments at different temperatures were carried out with typical coal samples taken from Xinjiang Liuhuanggou.The Langmuir,Freundlich and D-R adsorption were used to fit the isothermal adsorption curves,based on the theory of adsorption potential energy,coal sample adsorption thermodynamic characteristics of CO₂ and CH₄ were researched.The results indicate that the isothermal adsorption curve under different temperatures of CH₄ and CO₂ adsorption are in line with Langmuir,Freundlich and D-R equation model,that there is a negative correlation between the adsorption potential energy of CH₄ and CO₂ and the adsorption quantity,and there is a positive correlation between both the isosteric heat and entropy change and the adsorption quantity,the adsorption potential energy,isosteric heat,adsorption entropy change CO₂ are all greater than those of CH₄,that with increasing of temperature,the adsorption entropy of CH₄ and CO₂ decreased,that the changes in adsorption potential of CH₄ and CO₂ are not only affected by the surface force but also by the enthalpy of adsorption and adsorption entropy,that the CO₂ isosteric adsorption heat is affected by intermolecular competition and micropore filling,and that the adsorption thermodynamics parameters can be used to characterize the adsorption performance of coal sample,and reveal the nature of coal surface competitive adsorption.

Key words: methane, carbon dioxide, adsorption potential theory, isothermal adsorption, adsorption heat