If we pass a gaseous mixture such as air through a container containing a zeolitic adsorbent under high pressure and this adsorbent adsorbs nitrogen more intensely than oxygen, it can be expected that the exit gas is richer in oxygen because air passes through the bed and the adsorbent adsorbs most or all of the nitrogen present in the air. When the adsorbent bed reaches the end of its work cycle; That is, when its capacity to adsorb nitrogen is filled, the adsorbed nitrogen can be desorbed by reducing the pressure applied to the bed, and in addition to completing the gas separation process, the adsorbent bed can also be regenerated for reuse. In this case, the regenerated bed can be returned to produce the oxygen-rich from air cycle.

Regardless of the ability of adsorbents to differentiate between different gases, the adsorbents of pressure oscillation absorption systems are usually highly porous materials that are selected due to their high specific surface area. Common adsorbents used in the process of pressure swing adsorption are materials such as activated carbon, silica gel, alumina, resin and zeolite. Although the gas adsorbed on the surface of these adsorbents may consist of a layer as thick as one or at most several molecules, their specific surface area of ​​a few hundred square meters per gram allows the adsorbent to adsorb gas many times its own weight. In addition to being selective towards gases in a mixture, these adsorbents, specially a special type of adsorbent known as molecular sieves, separate gases based on their molecular size. In this case, the ability of the adsorbent to adsorb larger molecules is limited and we must use the appropriate model of this type of adsorbent based on the final target and the type of gas we want to separate.