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) o n the commercial 0.3 wt.-% Pt/Al2O3 reforming catalyst were investigat ed under isothermal chromatographic conditions using the elution techn ique in the temperature range 458-510 K. Average enthalpies of adsorpt ion were determined by using the isosteres obtained from experimental adsorption isotherms and compared with those calculated on the basis o f pulse retention data at infinite dilution for eleven C5-C-8 alkanes including the six mentioned above. The isotherms were also fitted to t he Langmuir equation for the evaluation of adsorption equilibrium coef ficients, Gibbs free energies, average adsorption enthalpies and entro pies.