The adsorptive characteristics of sodium Y zeolite for simple aromatic hydrocarbons, such as benzene, toluene, ethylbenzene, xylenes were investigated by means of gas chromatography at 140 to 280 ℃．For comparison, the adsorptive characteristics made from the isotherm curves, previously published, for cyclohexane, n-pentane and n-pentene on NaY zeolite were also checked. Sodium Y zeolite seems to form a homogeneous system for aromatic compounds. The amount adsorbed and the adsorption heat for benzene derivatives increase with the extent of alkyl substitution.
A linear relationship was confirmed between the decrease in the ionization potential of aromatic hydrocarbons and the increase in the initial heat of adsorption.
The Dubinin-Astarkhov's equation based on the Polanyi's theory was also applied on the adsorption system. The Dubinin-Astarkhov's equation was fitted well for cyclohexane and n-pentane but not for benzene derivatives and n-pentene. It was found that the adsorption with regard to the large pore zeolite such as sodium Y was preferably affected by the electrons and the extent of alkyl substitution rather than the kinetic diameter of adsorbate.