Determination of mass transfer and thermodynamic properties of branched paraffins in silicalite by inverse chromatography technique

Equilibrium isotherms and effective diffusivities of 3-methylpentane, isope ntane, and 2,2-dimethylbutane were measured between 150 and 300 degreesC by a linear inverse chromatography technique. The validity of the equilibrium data was checked with gravimetric experiments, and both sets of data are i n good agreement. The activation energies determined from the variation of the self-diffusivities with temperature lie in the range of literature resu lts. The following trend was observed for the self-diffusivities: isopentan e > 3-methylpentane >2,2-dimethylbutane. The effective diffusivities of the se compounds were found to increase with the adsorbed-phase loadings accord ing to Darken's law for a loading ratio less than 0.7. Above this value, th e diffusivities are higher than those given by Darken's law.