Molecular simulations in zeolitic process design

Abstract

Recent developments in molecular simulation techniques provide estimates of data, and valuable new insights, in the design of processes using zeolite adsorbents or catalysts. We illustrate these advances by considering a variety of examples such as separation of mixtures of linear and branched alkanes. Configurational-bias Monte Carlo (CBMC) simulations allow accurate determination of the sorption isotherms of alkanes and their mixtures in various zeolites. The CBMC simulations reveal subtle entropy effects that allow separations of alkane mixtures on the basis of the degree of branching. Novel and efficient separation processes can be developed by exploiting such entropy effects. Transition rate theories and molecular dynamics (MD) simulations allow the calculation of hopping rates of molecules and diffusivities within zeolites. Mixture diffusion in zeolites can be probed using kinetic Monte Carlo or MD simulations. These simulations help us understand the influence of correlations in molecular jumps. Such correlation effects have a profound influence on mixture diffusion characteristics. For the design of zeolite-based processes, a multi-scale modelling strategy is suggested.