Analyzing adsorption and diffusion behaviors of ethanol/water through silicalite membranes by molecular simulation

A methodology based on grand canonical Monte Carlo (GCMC) and NVT-ensemble equilibrium molecular dynamics techniques has been used to simulate the ethanol/water vapor mixture adsorption, diffusion and separation characteristics in silicalite crystal. The adsorption isotherms of pure ethanol and water consist with the literature experimental observations and other algorithm. The ethanol adsorption selectivity first reached the highest value of 85 at a feed ethanol concentration of ∼4 vol.% and then decreased with increasing the feed ethanol concentration. This also agreed with the literature experimental investigations. The diffusion coefficients of ethanol and water in the pure and mixture are also estimated by molecular dynamics. The results reveal that the effects of ethanol and water diffusion on separation are slight. We also used the permeation theory to estimate the pure ethanol and water permeance through silicalite membranes. All quantitative agreement of calculations with experiments suggests that the simulation method can be used to predict the performance of zeolite membranes.