Adsorption energy and structural heterogeneity of activated carbons

Abstract

Gas adsorption on activated carbons at supercritical temperatures takes place mainly in micropores of molecular dimensions due to the enhanced adsorption potential in such pores. Relationship between adsorption energy and pore sizes is used to analyze methane adsorption isotherms in order to obtain micropore size distribution. Isosteric heats of adsorption which are related to the adsorption temperature dependence are considered as additional information about the adsorption process and can be used for the verification of the model assumed. Adsorption isotherms of three carbon samples are analyzed, results of the two of them are consistent with the model of slit pores whereas in the case of the third carbon it seems that some other pore model should be considered. Gas chromatographic methods are also applied. In this method alkane molecular probes of different kinetic diameters are used to study the pore structure of these carbons.