On the diffusion of cyclohexane in ZSM-5 measured by zero-length-column chromatography

The sorption kinetics of cyclohexane in three samples of ZSM-5, differing i n size and morphology, were measured using the zero-length-column (ZLC) met hod. The diffusivities were found to be consistent across the samples and a gree well with data previously published in the literature, except that the small zeolite crystals exhibited values similar to those of the large part icles, contrary to some results. Inconsistencies with the standard model as sumptions were partly explained by the effect of the Langmuir-type adsorpti on equilibrium known to be a property of the system. These deviations do no t seem to diminish the validity of the measured diffusion coefficients. ZLC appears to be a very robust technique for diffusion measurements when anal yzed using the "long-time" solution method.