Separation factor of nitrogen-oxygen gas mixtures on carbon adsorbent

Abstract

1. In equilibrium and nonequilibrium adsorption of air components on the carbon molecular sieve CMS-4A in the room-temperature range, nitrogen and oxygen are adsorbed under equal conditions almost identically. The separation of air into components under near-equilibrium conditions can give only a very slight enrichment with oxygen, up to about 30%. Because of the absence of any significant difference in the kinetics of nitrogen adsorption, the use of the short-cycle adsorption technique will not give any positive effect. 2. The application of carbon sorbents to separate air into components is attractive only if a kinetic effect is present; if there is no kinetic effect, the use of carbon adsorbents is inadvisable from the thermodynamic point of view, owing to the small difference between the differential heats of adsorption of N2 and O2 and between the integration constants. 3. For approximate engineering calculations (with an accuracy of 10–15%), we can recommend precalculation of the temperature dependence of the separation factor in equilibrium adsorption of gas or vapor mixtures under the condition of applicability of the Langmuir equation, using only the individual adsorption isotherms for each component of the mixture.