The isotherms of adsorption with saturated and unsaturated hydrocarbon molecules on monovalent cation exchanged ZSM-5 zeolites were measured. The applicability ofhe theory of micropore volume filling, of the equation of Wilkins, and of the Langmuir adsorption equation to the adsorption systems studied was evaluated. The theoretical curves were obtained from the experimental data by the least square method with the aid of a computer. The results show that the Langmuir equation is applied satisfactorily to the adsorption systems of cyclohexane both on the hydrogen type and on the ionexchanged type of ZSM-5, but not to other systems. The values of limiting adsorption α0 calculated from regression equations agree fairly well with the experimental values. The initial heat of adsorption may be calculated from the Wilkins equation with two constants, C1 and C2, by which the part of isotherm curve at the lower pressure can be described well. Compared with the other two equations, the theory of micropore volume filling appears to be more satisfactory for the description adsorption systems studied and so the values of the three physical c constants, the limiting adsorption, α0, distribution order, n, and the characteristic adsorption energy, E, were calculated with it. In addition, this theory gives an evidence that adsorption of benzene and cyclohexane on ZSM-5 modified by alkali ions seems to depend mainly on the dispersion interaction with zeolite surface.

Key words: CALCULATION, ZEOLITE, ADSORPTION, ADSORPTION, MOLECULAR SIEVE, ORGANONITROGEN COMPOUNDS, ZEOLITE ZSM-5, ISOTHERM, LEAST SQUARE METHODS, LINEAR EQUATIONS