STUDY OF CARBON MICROSTRUCTURE BY USING INVERSE GAS-CHROMATOGRAPHY

Carbons with different pore structures were studied by means of inverse gas chromatography at infinite dilution and finite concentration. Thermodynamic quantities, such as the enthalpy or the free energy of adsorption, are dependent on the carbon micropore structure. Normal alkanes in conjunction with their branched isomers having different critical diameters were used to assess the molecular sieving properties of the investigated carbons. Chromatographic measurements at finite concentration yielded adsorption isotherms, and from these the isosteric heat of adsorption as a function of amount adsorbed for the parent n-alkane and its isomers were calculated. Both isotherms and isosteric heats of adsorption are consistent with the carbon pore structure.