A combination of dynamic Monte Carlo and quantum calculation methods was proposed to estimate the diffusion coefficient and permeance in zeolite systems. Results were presented for the estimation of the diffusion coefficient and permeance of aromatic molecules in MFI-type silicalite and Mg ion-exchanged ZSM-5 intercrystalline/membranes. The parameter required for dynamic Monte Carlo use was obtained by performing a PM3 calculation. The predicted diffusion coefficients of xylene isomers, benzene and toluene were qualitatively consistent with previously reported results. The permeance of xylene isomers through the silicalite and MgZSM-5 membranes was calculated using a non-equilibrium dynamic Monte Carlo method. MgZSM-5 membranes exhibited a greater selectivity for p-xylene from among xylene isomers than that of the silicalite membranes. Results of the PM3 calculation provided evidence that the Mg ion functioned as the attractive site for xylenes.

Estimation of Diffusion Coefficient and Permeance of Aromatic Molecules in Silicalite and MgZSM-5 using Quantum Calculation and Dynamic Monte Carlo Simulation. H.Takaba, T.Suzuki, S.I.Nakao: Fluid Phase Equilibria, 2004, 219[1], 11-8