MONTE-CARLO SIMULATIONS OF EXTRAFRAMEWORK CATION POSITIONS IN DEHYDRATED ZEOLITE LIX (SI-AL = 1.25)

A knowledge of extraframework cation positions is crucial for understa nding the adsorption and catalytic properties of zeolites. However, di ffraction met hods are not always able to provide this information wit h sufficient reliability. Li-containing zeolites (LiLSX, LiX), for exa mple, are particularly difficult to characterize experimentally becaus e of the small X-ray and neutron scattering amplitudes of lithium. The situation is aggravated by the location of Li ions in general positio ns with low partial occupancies. we show how simulation tools can deal with the partial statistical disorder of the supercage Li cations in zeolite LiX (Si:AL = 1.25) and especially demonstrate the efficacy of canonical (N, V, T) Monte Carlo simulations for understanding the cati on placements in such systems. (C) Academie des sciences/Elsevier, Par is.