Evaluation of hydrophilic-hydrophobic character of zeolites by measurements of their immersional heats in water

Na-type faujasite was modified by SiCl₄ treatment under dealumination-silicon-exchange reaction. Their crystallinities and lattice constants were analyzed by x-ray diffraction, and their surface areas and pore structures were measured by nitrogen adsorption at 77 K. Their hydrophobic characteristics were evaluated by measurements of water adsorption and heats of immersion into weter, and compared with those of ZSM-5 zeolites which were highly silicious at the synthesis process.Adsorption amount ofn-hexane on modified faujasite did not change compared to that on original faujasite, however, the adsorbed amount of water greatly decreased. Heats of immersion in water decreased by the modification and were closely related with the Si/Al ratio of zeolites. Hydrophilic-hydrophobic character is discussed from the viewpoint of water contact angle.