Pore Size Distribution Analysis and Networking: Studies of Microporous Sorbents

Abstract

We present an impioved method, based upon nonlocal density functional theory, for determining the pore size distribution (PSD) of microporous materials from adsorption measurements. The analysis method is applied to adsorption data for nitrogen on porous carbon. The PSDs obtained using nonlocal theory are compared to PSDs calculated from the Kelvin equation and from the Horvath-Kawazoe method. Our results indicate that nonlocal theory provides a much more accurate interpretation of the PSD than previous methods have accorded, particularly for highly microporous sorbents. Neither the Kelvin equation nor the Horvath-Kawazoe method adequately reproduces the low pressure region of the carbon isotherm, while nonlocal theory gives a quantitatively accurate fit over the full range of the isotherm. Nonlocal theory predictions of pore filling pressures also compare favorably with Gibbs ensemble Monte Carlo simulation results.