6533b86ffe1ef96bd12cdbbb

RESEARCH PRODUCT

Sorption of argon and nitrogen on network types of zeolites and aluminophosphates

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description

Abstract Synthetic zeolites and aluminophosphates comprising 10- and 12- membered ring openings, unidimensional and network type of pore systems (MFI, MEL, ERI, LTA, AEL, AFI and FAU) were used as model adsorbents to examine the impact of micropore structure on the sorption properties. Argon and nitrogen were employed as adsorptives. Adsorption measurements were carried out on gravimetric and volumetric sorption devices and also monitored by microcalorimetry. From the low coverage regime of the isotherm Henry's constants and isosteric heats of adsorption were derived. Both quantities allowed the discrimination between 10- and 12- membered ring systems. Unidimensional 10- and 12- membered ring zeolites and aluminophosphates gave Type I isotherms for argon and nitrogen. Stepped isotherms were observed for argon and nitrogen on network types of molecular sieves. On MFI type zeolites with nitrogen a distinct hysteresis was observed between p/p o = 0.1 and 0.15, as reported earlier. In-situ measurements of the system Silicalite I / nitrogen at 77 K by neutron diffraction experiments indicated discontinous changes in the diffraction pattern of both MFI and nitrogen upon increasing adsorbate coverage.