Molecular dynamics simulation of ethene diffusion in MFI and H[Al]ZSM-5

Abstract

Molecular dynamics (MD) simulation was performed for studying ethene diffusion in the lattices of orthorhombic MFI, monoclinic MFI and H[Al]ZSM-5 at 300 K. Diffusion trajectories show that ethene molecules are polarized most at the edges of channel intersections and least at the centers of channel segments. Al substitution slightly increases molecular dipole moment, but hardly affects the molecular electronegativity. H addition decreases the molecular dipole moment, but enhances the molecular electronegativity. Molecules prefer locations at the centers of channel intersections, especially those near Al substitutions. Meanwhile, molecular spectra and diffusion characteristics, i.e. atomic and molecular translational temperatures, kinetic, potential and total energies, diffusion coefficients, heats of adsorption and interactions, etc., have been discussed.