The adsorption and desorption characteristics of shale is very important for the development of shale gas. For the sake of thorough understanding the adsorption mechanism in micro-scale view for clay minerals in the shale

three molecular models including illite

montmorillonite and kaolinite were established by using molecular simulation software Material Studio

the grand canonical Monte Carlo (GCMC) method was used for the calculation of isotherm adsorption capacity and adsorption heat. At the same temperature and pressure

isotherm adsorption capacity of CH4 in three clay minerals was in the sequence below: illite>montmorillonite>kaolinite. With the increase of pressure

the isotherm adsorption capacity of CH4 in three clay minerals increased

and CH4 adsorption in illite

montmorillonite was more sensitive to pressure changes than that in kaolinite. The heat of adsorption of three clay minerals were less than 42 kJ·mol-1

proving that adsorption of CH4 was physical adsorption. With the increase of temperature

the adsorption heat of CH4 reduced and the isotherm adsorption capacity of CH4 was decreased

suggesting that high temperature was disadvantageous to adsorption of CH4.