ADSORPTION BY MFI-TYPE ZEOLITES EXAMINED BY ISOTHERMAL MICROCALORIMETRY AND NEUTRON-DIFFRACTION .1. ARGON, KRYPTON, AND METHANE

The physisorption of argon, krypton, and methane on silicalite-I and of argon on a series of MFI-type zeolites with varying Si/Al ratios is examined by isothermal volumetry, microcalorimetry, and neutron diffraction. Adsorption of argon and krypton is shown to occur by site on silicalite-1. Both molecules undergo transition from a ''disordered phase' (presumably a fluid) to ''crystalline-like solid phase', whereas methane remains in a disordered phase. At low coverage, the adsorption of argon on the MFI-type zeolites shows no specificity to aluminum composition, whereas the transition at higher coverages becomes more diffuse with increasing aluminum content.