Sorption and Sorption Kinetics of Ethylbenzene in MFI-Type Zeolites Studied by a Barometric Technique

Abstract

The sorption and sorption kinetics of ethylbenzene in H-ZSM-5 zeolites was studied varying the experimental conditions over a broad range of temperature and concentration. Isotherms and heats of adsorption as well as intracrystalline diffusivities have been determined. The isosteric heat of adsorption decreases with increasing sorbate loading due to repulsive sorbate-sorbate interaction. The diffusivity remains independent of sorbate concentration at loadings lower than a critical value of about four molecules per unit cell, while a sharp decrease is observed at higher loadings. The critical concentration slightly depends on the temperature. The relationship between diffusivity, concentration and temperature can be tentatively interpreted in terms of a complex sorbate-sorbent interaction.