6533b824fe1ef96bd128088c

RESEARCH PRODUCT

Sorption Studies on Large ZSM-5 Crystals: The Influence of Aluminium Content, The Type of Exchangeable Cations and the Temperature on Nitrogen Hysteresis Effects

subject

description

Abstract In comparison to polycrystalline powder large ZSM-5 crystals are best suited for high resolution sorption experiments. The nitrogen isotherms on HZSM-5 at 77 K reveal a pronounced hysteresis loop. The shape and position of the hysteresis relative to the pressure axis has been found to be affected by the aluminium content of the zeolite, the type of framework cation and the sorption temperature. The occurence of the hysteresis and its changes are assigned to a transition from a liquidlike to a solid-like adsorbed phase of nitrogen. The micropore volume v mp derived from the argon and nitrogen isotherm (s. Fig. 2b, first plateau) and calculated according to DUBININ-RADUSHKEVICH was consistent with the pore volume obtained from the apparent densities with respect to helium and mercury.