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

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, Theta(i,sat), of linear alcohols and alkanes have integer values in a certain range of C numbers. In this range, the Theta(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 Theta(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. (c) 2010 Elsevier B.V. All rights reserved.