Maxwell–Stefan Modeling of Ethanol and Water Unary Pervaporation through a High-Silica MFI Zeolite Membrane

Abstract

The pervaporative mass transfer of pure ethanol and water through a thin (0.5 μm) supported high-silica MFI membrane was studied experimentally at 30–70 °C, and modeled on the basis of the Maxwell–Stefan formalism. The temperature dependency of adsorption was described with the temperature dependency of pure component saturated vapor pressure. Two scenarios of coverage dependency, i.e., coverage-dependent and coverage-independent Maxwell–Stefan diffusivity, were applied in the modeling of the mass transfer through the zeolite film. In addition, the mass-transfer resistance of the support layers was taken into account. The derived unary models provided good representations of ethanol and water pervaporation flux. The study illustrates that pure component steady-state pervaporation flux measurements at different conditions offer a feasible basis for determining diffusion coefficients. Basically, pure component adsorption isotherms and derived diffusivities can be used in the modeling of pervaporative mass transfer of mixtures using zeolite membranes.