Experimental comparison of CO2, CH4, and N2adsorption capacity on typical Chinese coals at different temperatures

Competitive adsorption of CO2/N-2/CH(4)on coals is important to evaluate potential application of CO2- or N-2- ECBM, which is not fully addressed in previous studies. In this paper, CH4, CO2, and N(2)adsorption behaviors are experimentally compared at different reservoir temperatures (307 K, 318 K, and 333 K) and pressure up to 9 MPa. It is found that adsorption capacities all decrease with increasing temperature for CH4, CO2, and N-2, while the differences in maximum adsorption capacity at different temperatures is not significant. Maximum adsorption capacity of anthracite coal is much larger than those of bituminous coals, while the maximum adsorption capacities of two selected bituminous coal are close to each other. The maximum adsorption capacity of CO(2)is 1.93 mmol/g?which is significantly higher than that of CH(4)and N(2)with exactly 1.80 mmol/g and 1.11 mmol/g respectively. However, for a given coal sample, gas type does not affect the thermal-stimulated desorption capacities significantly.