Thermodynamic analysis of adsorption process at a non-equilibrium steady state

By using the non-equilibrium thermodynamic approach,the possibility of the existence of a steady state for non-equilibrium adsorption with a temperature difference between body gas and adsorbed gas was confirmed and the steady state was determined.The chemical potential difference between body gas and adsorbed gas was obtained and equations for evaluating the adsorption entropy and the isosteric heat of adsorption were derived.The changes of the adsorption entropy and the isosteric heat of adsorption at the non-equilibrium steady state relative to those at the equilibrium state were calculated and the results were compared with those obtained using the traditional equilibrium thermodynamic method.The comparison suggests that the changes of the adsorption entropy and the isosteric heat of adsorption obtained using the non-equilibrium thermodynamic approach are related with not only temperature but also adsorptive state,while those obtained using the equilibrium thermodynamic method are only a function of temperature.The main reason is that the present study treats the adsorption and gas temperature change as an integrated process and considers their interaction,whereas the equilibrium thermodynamic approach separates the adsorption and gas temperature change as two independent processes and neglects their interaction.