ADSORPTION OF GASEOUS P-XYLENE AND M-XYLENE ON NAY, KY, AND BAY ZEOLITES .2. MODELING - ENTHALPIES AND ENTROPIES OF ADSORPTION

The adsorption isotherms of xylenes are described by Henry's law and Langmuir's model on NaY and KY and the Dubinin-Radushkevich model on BaY. The isoteric enthalpies of adsorption show on each zeolite that the adsorbate-adsorbent interactions are nearly the same with both isomers. They are stronger on BaY than on NaY and KY. The adsorbate-adsorbate interactions are stronger with m-xylene than with p-xylene and especially outstanding on KY, The entropies of adsorption show that the mobility of the adsorbate is fewer with m-xylene than with p-xylene, The isosteric free enthalpies of adsorption are related to the acidity of each zeolite. BaY has a stronger acidity and a greater ability to adsorb xylenes than NaY and KY.