Intracrystalline diffusion of benzene in microporous gallosilicate with MFI structure

Abstract

Adsorption equilibrium and kinetic data have been measured for benzene on microporous gallosilicate with MFI structure (MFI-ZAG, zeolite analogous gallosilicate) over the temperature range 300–350 K. The sorption capacity is similar to that for Ga-free MFI systems. The sorption heat is found to be constant over the entire concentration range considered. Sorption kinetics were measured by a constant-volume–variable-pressure method and evaluated via the formalism of the Volterra integral equation technique (program package ZEUS). Intracrystalline diffusion was found to govern the rate of sorption uptake. Corresponding diffusivity data could be calculated as concentration and temperature dependences. The intracrystalline diffusivity can be described fully by the Barrer constant-jump-length model. The sorption data are compared with those for another MFI-ZAG sample synthesized under modified conditions.