Adsorption of benzene and cyclohexane on faujasite-type zeolites. Part 1.—Thermodynamic properties at low coverage
The adsorption of benzene and cyclohexane has been studied on X, Y and aluminium-deficient X and Y zeolites with various sodium ion contents. Equilibrium constants, enthalpies of adsorption, virial coefficients and surface interactions have been determined. At a constant temperature, equations correlating equilibrium constant of adsorption with either cation content or enthalpy of adsorption have been derived. Results for benzene are consistent with specific interactions of its π electrons with zeolite surface. These interactions allow the surface field changes with Na or Al atom content to be easily detected. Cyclohexane which has small interactions with surface sites indicates only small changes in properties with chemical composition. The two hydrocarbons show specific changes in adsorption properties near 25–30 sodium or aluminium atoms per unit cell.