A modified Horvath-Kawazoe method for micropore size analysis

摘要

The Horvath-Kawazoe (HK) method is a semi-empirical, anlaytic model of adsorption in micropores that is commonly used for determining the pore size distributions (PSDs) of microporous materials. The HK method is a substantial improvement over classical adsorption models 9e.g. Kelvin-based methods) in that the adsobate potential interactions with the adsorbent surfaces are explicitly accounted for. One of the principal shortcomings of the original HK method, however, is that the mean potential energy change due to adsorption is calcualted from an unweighted average over position within the micropore. It is known from molecular simulation studies of adsorption at subcritical temperatures that the local density of the adsorbate in the pore varies strongly with position due to fluid layering near the pore walls. The omission of this structure dependence from the original HK model leads to an overestimation of micropore filling pressures relative to the exact filling pressures calculated from molecular simulations.