The adsorption equilibria of water vapor on zeolite 3A, zeolite 13X, and dealuminated Y zeolite (DAY) were measured using a volumetric method. Equilibrium experiments were conducted at 293.15, 303.15, and 313.15 K and at relative pressure (P/P s ) up to 0.95. Experimental data were correlated using Aranovich−Donohue and Frenkel−Halsey−Hill models, using Langmuir, Toth, UNILAN, and Sips isotherms.

The adsorption equilibria of water vapor on an alumina/zeolite 13X composite and silica gel were measured at 293.15, 303.15, and 313.15 K and at relative pressures (P/P s) of up to 0.95. The experimental isotherms were compared with those of zeolite 13X and alumina. The data were correlated by the Dubinin–Astakhov (DA) model and the Aranovich–Donohue (AD) model using Sips and Toth isotherms. The heats of adsorption were in the range of 50–59 kJ·mol–1 for silica gel but decreased from 75 to 45 kJ·mol–1 for the alumina/zeolite 13X composite with increased loading. The composite showed much higher adsorption affinities and adsorption amounts than did silica gel in the low-pressure range, owing to the characteristics of zeolite 13X. However, at increased pressures, the isotherm shape for the composite was similar to that for alumina.

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