RELATIONSHIP BETWEEN ENERGETIC AND STRUCTURAL HETEROGENEITY OF MICROPOROUS CARBONS DETERMINED ON THE BASIS OF ADSORPTION POTENTIALS IN MODEL MICROPORES

The relationship between adsorption energy and micropore sizes is based on the dependence of the molecule-pore interaction potential well depth as a function of the pore width. The adsorption integral equation is used to analyze experimental adsorption isotherms of several simple gases measured at supercritical and near-critical temperatures on two microporous carbons. It is observed that the adsorption systems are strongly heterogeneous from the standpoint of their adsorption energetics which are characterized by asymmetrical energy distributions with a broadening toward high energies. It is also shown that these distributions correspond to relatively narrow and symmetrical peaks characterizing the distribution of pore sizes. The strong asymmetrical relationship between adsorption energy and pore width magnifies the energetic heterogeneity even though pore size distributions show only modest dispersion.