THERMODYNAMICS OF HIGH-PRESSURE ADSORPTION OF ARGON, NITROGEN, AND METHANE ON MICROPOROUS ADSORBENTS

Adsorption equilibria of argon, nitrogen, and methane on the 13X molec ular sieve and the AS activated carbon were measured at five temperatu res over a nide pressure range from 0.1 to 20 MPa using a microbalance . From experimental adsorption isotherms, which are excess functions, the absolute isotherms were calculated using equations of state for a real gas phase. Grand canonical Monte Carlo simulations and density fu nctional theory calculations were carried out in order to explain spec ific features of the resulting isotherms. Different thermodynamic func tions evaluated from the excess and absolute adsorption isotherms were analyzed over a wide pressure range at the average temperature of the range studied.