Pressure Swing Adsorption (PSA) is a popular technology which is used to separate some gas species from a mixture of gases under pressure. This is achieved as per the species' molecular characteristics and affinity for an adsorbent material. PSA operates at near-ambient temperatures. It differs from cryogenic distillation techniques of gas separation. Special adsorptive materials (for example: zeolites) are used as a molecular sieve, preferentially adsorbing the target gas species at high pressure. The process then swings to low pressure to desorb the adsorbent material.


By making use of two adsorbent vessels, near-continuous production of the target gas is allowed. It also permits so-called pressure equalization, where the gas leaving the vessel is depressured. This gas is used to partially pressurize the second vessel. This leads to significant energy savings, and is common industrial practice.

PSA Oxygen Technology
Oxygen PSA units typically use zeolite molecular sieve to adsorb nitrogen, carbon dioxide, residual water vapor and other gases together with alumina to remove much of the water vapor from the air feed. Typical oxygen PSA delivery pressures leaving the unit are one to three atmospheres. Oxygen purity is typically between 90 and 95%; limited primarily by the argon content, which is usually around 4.5 to 5%.