We performed Configurational-Bias Monte Carlo simulations to provide adsorption isotherms, Henry coefficients and heats of adsorption of alkanes in sodium exchanged MFI- and MOR-type zeolites. We derived empirical expressions from the simulation data to describe the adsorption of linear alkanes in sodium exchanged MFI structures. These expressions adequately describe the Henry coefficient and adsorption enthalpy of n-alkanes as a function of sodium density and temperature. In the high coverage regime we provide an expression for saturation capacities of n-alkanes in the zeolite that combined with the obtained for Henry coefficients, gives a direct estimation of the complete adsorption isotherms of pure adsorbents and mixtures.