Liquid-phase adsorption of binary ethanol–water mixtures on NaZSM-5 zeolites with different silicon/aluminium ratios

A systematic study was made on the adsorption of ethanol–water mixtures on NaZSM-5 zeolites, synthesized with different Si/ Al ratios. The excess isotherms were analysed by means of energetic homogeneous and energetic heterogeneous adsorbent models. For the first model, the equilibrium constants increase with increased Si/ Al ratio. Using the model of an energetic heterogeneous adsorbent, an energy difference distribution function with two maxima appears, which is due to London-type interactions and the specific interactions of the zeolites with the adsorbed molecules.