PORE-SIZE DISTRIBUTION ANALYSIS OF MICROPOROUS CARBONS - A DENSITY-FUNCTIONAL THEORY APPROACH

We present an improved method, based upon density functional theory, f or the determination of the pore size distribution (PSD) of porous sor bents. The adsorption isotherms predicted by nonlocal mean field theor y for individual slit pores are correlated as a function of pressure a nd pore width. The PSD is then calculated by fitting this correlation to the experimental adsorption isotherm of the sorbent. We apply the a nalysis method to adsorption data for nitrogen on several porous carbo ns. In this application, the porous network is modeled as a continuous size distribution of noninteracting slit-shaped graphitic pores. The PSDs obtained by using the Kelvin equation and using the local and non local versions of the mean field density functional theory are compare d and evaluated. The results demonstrate that nonlocal theory provides a more accurate interpretation of the PSD than previous methods have achieved, particularly when the analysis is applied to highly micropor ous sorbents.