CO2 SORPTION ISOTHERMS IN LTL ZEOLITES

Isotherms Of C02 sorption in KL, HKL, Na(I)KL, and Na(2)KL in the temperature range 273-393 K have been measured. The equilibrium sorption capacity at 400 Torr was found to increase in the order HKL < KL < Na(I)KL < Na(2)KL. The sorption data were analyzed in terms of different models of sorption isotherm equations. Dubinin, Langmuir, and Freundlich isotherm models could represent the sorption data satisfactorily, yielding linear plots. BET and Sips sorption models showed limited applicability with linear plots only in the low-coverage region. The chemical potential of sorption also followed the same sequence as that of equilibrium sorption. The rate of drop of chemical potential, however, showed the reverse order. The isosteric heat Of CO2 sorption, calculated by using the Clausius-Clapeyron equation, was found to be temperature independent and ranged between 27 and 46 kJ/mol. Zeolite KL offered the most homogeneous surface for C02 sorption.