Sieving characteristics: Carbon molecular sieves utilize sieving properties to separate oxygen and nitrogen. They contain a vast network of micropores that allow molecules with small kinetic diameters to diffuse rapidly into the pores while restricting the entry of larger molecules.
Pore size control: During manufacturing, the micropore distribution is engineered based on molecular dimensions, typically within the 0.28–0.38 nm range. This specific pore size range allows oxygen molecules to pass through quickly while hindering nitrogen molecules, thereby enabling oxygen-nitrogen separation.
Adsorption process: When a gas mixture passes through the carbon molecular sieve, macropores and mesopores act primarily as channels, transporting molecules destined for adsorption (such as oxygen) into the micropores and ultramicropores. These micropores and ultramicropores constitute the actual volume where adsorption takes place.
Pressure Swing Adsorption (PSA): In PSA nitrogen generation systems, carbon molecular sieves serve as the adsorbent, extracting nitrogen directly from compressed air based on the pressure swing principle. Under pressure, the diffusion rates of oxygen and nitrogen within the sieve differ significantly; a large number of oxygen molecules are adsorbed by the sieve in a short time, while nitrogen molecules become enriched in the gas phase, thus achieving separation.
Regeneration and cycling: Because the oxygen adsorption capacity of carbon molecular sieves varies markedly with pressure, reducing the pressure releases the adsorbed oxygen molecules, thereby regenerating the sieve. This process cycles repeatedly to ensure continuous nitrogen production.