Development of thermodynamically consistent, experiment-based molecular models of diffusion through thin microporous membranes

Abstract

Abstract Thermodynamic consistency in developing experiment-based molecular models of diffusion through microporous membranes is imperative for accurate prediction of both steady state and transient permeation properties. In this paper we present a multiscale approach to developing thermodynamically consistent molecular models of diffusion through very thin single-crystal mciroporous membranes. We employ a generalized kinetic Monte Carlo model to represent complex atomistic zeolite topologies as representative lattices of binding sites. Equilibrium Monte Carlo simulations yield self-diffusivities within these structures, validated here via comparison to PFG-NMR experimental data. A rational factorial design simulated annealing fit of the full equilibrium kinetic Monte Carlo model to experimental isotherms enables direct extraction of adsorption and desorption parameters from macroscopic experimental data. The result is a self-consistent model describing adsorption, desorption, and migration within the zeolite lattice. Armed with this thermodynamically consistent odel, we employ gradient continuous time Monte Carlo simulations as a means to model diffusion of benzene through very thin, single-crystal NaY zeolite membranes.