Multisite Langmuir model applied to the interpretation of sorption of n-paraffins in 5A zeolite

Adsorption equilibrium isotherms of n-paraffins from methane to decane on 5A zeolites (crystals and pellets) were compiled in a wide range of temperature and pressure. The data were correlated using the MSL (multisite Langmuir) model for homogeneous surfaces. It is shown that it is possible to correlate all adsorption isotherms by maintaining thermodynamic consistency on model parameters. However, for paraffins with more than seven carbons it is necessary to account for the effects of lateral interaction of adsorbed molecules. The heat of adsorption for C-1-C-10 paraffins linearly increases with the carbon number, ranging from 4.6 kcal/mol for methane up to 23.2 kcal/mol for n-decane.