(436a) Competitive and Cooperative Adsorption of Ethanol on ZIF-8 in the Presence of 1-Butanol

The Metal Organic Framework ZIF-8 has been studied extensively in the context of the recovery of renewable alcohols produced via fermentation. The vapor and liquid phase adsorption isotherms of these linear alcohols on ZIF-8 do not have a classical Type I shape, but show a distinctive S-shape, containing an inflection point. In this work, the effect of the isotherm shape on competitive adsorption of ethanol and 1-butanol was investigated. The Ideal Adsorbed Solution Theory (IAST) was used to predict the binary adsorption equilibria on ZIF-8 for ethanol and 1-butanol. IAST predictions showed that the presence of 1-butanol at low partial pressures, increases the equilibrium capacity of ethanol. These predictions were further investigated via Monte Carlo simulations, to study the molecular interactions governing this cooperative effect. Breakthrough experiments with binary ethanol/1-butanol mixtures at different ratios were performed to confirm the cooperative adsorption of ethanol. The experimental breakthrough profiles were modeled, employing IAST to predict the equilibrium capacities during the dynamic simulations. The developed dynamic model using IAST was able to accurately describe the influence of the isotherm shape on the experimental breakthrough profiles.