ADSORPTION AND ENERGETICS OF XENON IN MORDENITE - A MONTE-CARLO SIMULATION STUDY

Grand canonical Monte Carlo (GCMC) simulations were used to calculate energy contour maps, isodensity surfaces and adsorption isotherms of x enon in purely siliceous mordenite at 300 K using previously published potential parameters. Then, in order to understand the effect of alum inum content, Al-containing mordenites were modeled by adding the appr opriate negative charge to each of the oxygen atoms in the mordenite f ramework and by inserting Na+ ions at fixed extra-framework positions previously identified from x-ray crystallographic data. GCMC simulatio ns were again performed using these structure models. Both main channe l and sidepocket xenon adsorption were observed in all mordenite struc tures. The sidepockets were found to be only singly occupied whereas t he main channel allowed multiple occupancy. Sidepocket xenon adsorptio n became more favorable when cations (and aluminum) were introduced. I n the main channel, xenon adsorbed into localized sites that were dist ributed in an octahedral arrangement within each unit cell with two ap ices in front of opposing sidepockets. These sites remained at the sam e location over the entire range of loading (0-16 Xe/unit cell) and ca tion (and aluminum) content. (C) 1995 American Institute of Physics.