Gas separation

Gas separation can refer to any of a number of techniques used to separate gases, either to give multiple products or to purify a single product.

Pressure swing adsorption
Pressure swing adsorption (PSA) pressurizes and depressurizes a multicomponent gas around an adsorbent medium to selectively adsorb some components of a gas while leaving other components free-flowing.

Vacuum swing adsorption
Vacuum swing adsorption (VSA) uses the same principle as PSA but swings between vacuum pressures and atmospheric pressure. PSA and VSA techniques may be combined and are called "vacuum pressure swing adsorption" (VPSA) in this case.

Temperature swing adsorption
Temperature swing adsorption (TSA) is similar to other swing adsorption techniques but cycles the temperature of the adsorbent bed-gas system instead of the gas pressure to achieve separation.

Cryogenic distillation
Cryogenic distillation is typically only used for very high volumes because of its nonlinear cost-scale relationship, which makes the process more economical at larger scales. Because of this it is typically only used for air separation.