Adsorption characteristics of methane on coal under reservoir temperatures

Abstract：In order to study the adsorption characteristics of methane on coal with different pore structures under reser- voir temperatures, the coal sample was treated by mixed acid, and was characterized by N2 adsorption. Methane adsorp- tion was conducted at temperatures of 25,40,55 ~C within the pressure range of 0-3.5 MPa. The Langmuir equation was applied to fitting the experimental data. The results show that the pore structure and temperature have significant effects on the adsorption capacity of coal. The surface area, pore volume and micropores are enhanced for the treated coal sample, resulting in the increase of the amount of methane adsorption. With the temperature increasing, the ad- sorption capacities decreases, which is in good agreement with the saturated adsorption amount, and the larger the pres- sure is, the stronger the change tendency becomes. Moreover, the Polanyi adsorption potential theory was employed to fit the data, and the results represent that the adsorption characteristic curve is independent of temperature. The ad- sorption potential and adsorption capacity increases with the treated coal sample, suggesting that the pore structure plays an important role in the variation of adsorption capacity.