Adsorption is one of the main mechanisms involved in the ECBM process, a technology where CO2(or flue gas, i.e. a CO2/N2mixture) is injected into a deep coal bed, with the aim of storing CO2by simultaneously recovering CH4. A detailed understanding of the microscopic adsorption process is therefore needed, as the latter controls the displacement process. A lattice DFT model, previously extended to mixtures, has been applied to predict the competitive adsorption behavior of CO2, CH4and N2and of their mixtures in slit-shaped pores of 1.2 and 8nm width. In particular, the effect of temperature, bulk composition and density on the resulting lattice pore profiles and on the lattice excess adsorption isotherms has been investigated. Important insights could be obtained; when approaching near critical conditions in the mesopores, a characteristic peak in the excess adsorption isotherm of CO2appears. The same effect could be observed neither for the other gases nor in the micropores. Moreover, in the case of mixtures, a depletion of the less adsorbed species close to the adsorbent surface is observed, which eventually results in negative lattice excess adsorption at high bulk densitie
