ADSORPTION PARAMETERS OF SOME C5-C-8 PARAFFINIC HYDROCARBONS ON PLATINUM ALUMINA BY GAS-CHROMATOGRAPHIC PULSE TECHNIQUES

Adsorption isotherms of six C5-C-8 paraffinic hydrocarbons (n-pentane, n-hexane, n-heptane, iso-octane, cyclohexane and methylcyclohexane) on the commercial 0.3 wt.-% Pt/Al2O3 reforming catalyst were investigated under isothermal chromatographic conditions using the elution technique in the temperature range 458-510 K. Average enthalpies of adsorption were determined by using the isosteres obtained from experimental adsorption isotherms and compared with those calculated on the basis of pulse retention data at infinite dilution for eleven C5-C-8 alkanes including the six mentioned above. The isotherms were also fitted to the Langmuir equation for the evaluation of adsorption equilibrium coefficients, Gibbs free energies, average adsorption enthalpies and entropies.