Study on heat adsorption based on the experiment of coal adsorption of methane by using the weight method

The study of heat adsorption plays an important role in understanding the mechanism of methane adsorption from coal. The gravimetric method was used to conduct 303 K, 308 K, and 313 K isotherm adsorption experiments on two sets of coal samples; the equivalent heat adsorption of methane adsorption by coal was calculated, and the thermodynamic properties of coal adsorption of methane were analyzed. The research results showed that the calculated isometric heat of adsorption is 30.51 kJ/mol and 23.14 kJ/mol in the experimental temperature, pressure, and corresponding adsorption capacity, respectively, indicating that the adsorption of methane by coal belongs to physical adsorption. The increase in adsorption capacity increases monotonously and slowly, which is the result of the dominant interaction force between the adsorbed methane molecules. The 318 K isotherm adsorption characteristics are predicted using the 303 K and 313 K isothermic adsorption heat data, which are compared with the laboratory measured isotherm adsorption data. The two groups have the same trend. The relative errors of the two groups of coal samples are between 2.26%-5.72% and 0.29%-2.19%, respectively. A new method is proposed for using isosteric heat adsorption to predict isothermal adsorption characteristics under different temperature and pressure conditions