Entropy-based separation of linear chain molecules by exploiting differences in the saturation capacities in cage-type zeolites

Abstract

For zeolites such as CHA, LTA, DDR, ERI, AFX, and TSC that consist of cages separated by narrow windows, the saturation capacities expressed as molecules per cage, Θ_i,sat, of linear alcohols and alkanes have integer values in a certain range of C numbers. In this range, the Θ_i,sat decreases in a step-wise manner with increasing chain length. Using Configurational-Bias Monte Carlo simulations, we demonstrate the potential of separation of binary mixtures of linear chain molecules that exploits the differences in the Θ_i,sat. This separation principle can lead to an almost total exclusion of the longer molecule in preference to the shorter one, as cage saturation conditions are approached.