A DIRECT ASSESSMENT OF MEAN-FIELD METHODS OF DETERMINING PORE-SIZE DISTRIBUTIONS OF MICROPOROUS MEDIA FROM ADSORPTION-ISOTHERM DATA

The ability of mean-field-based theories to extract pore size informat ion from adsorption isotherms of microporous materials is assessed. Th ese theories represent natural and simple extensions of the Kelvin equ ation commonly applied in mesopore analysis. Adsorption behavior for a number of model spherical micropores is accurately determined using s tatistical mechanics. Using these results, pore sizes are calculated v ia a prototypical mean-field method proposed by Horvath and Kazawoe an d compared to the true values. Although moderately accurate, it is fou nd that several key underlying assumptions in the method limit its qua lity. Most notably, simple mean-field approaches calculate polydispers e pore size distributions for systems which are in fact monodisperse i n pore size. Improvements to the methodology are discussed and explore d.