Nonideality in the Adsorption of Ethanol/Ethyl Acetate/Water Mixtures On ZIF-8 Metal Organic Framework

Fisher esterification of acetic acid (or acetic anhydride) with ethanol (EtOH) is the main industrial process for the synthesis of ethyl acetate (EA). Nonetheless, the separation of the produced ester from ethanol is challenging since these volatile organic compounds (VOCs) form an azeotropic mixture. In this work, the adsorption and separation EtOH/EA/water mixtures on the ZIF-8 metal-organic framework is studied. The present study aims to characterize the adsorptive behavior of ZIF-8 with non-ideal EtOH/EA/water mixtures. Single and multicomponent adsorption isotherms, obtained by gravimetry and breakthrough experiments, show high adsorption capacity and selectivity toward ethyl acetate. Pulse chromatography experiments confirm the higher interaction strength between EA and ZIF-8 in the low-pressure range at a low degree of pore filling (Henry's region). The breakthrough profiles show development of intermediate plateaus in specific concentration ranges, with complex breakthrough evolution that has been modeled using a combined ideal and real adsorption solution theory model to accounts for deviations from ideality.