Gas separation can refer to any of a number of techniques used to separate
gas
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
es, either to give multiple products or to purify a single product.
Swing adsorption techniques
Pressure swing adsorption
Pressure swing adsorption (PSA) pressurizes and depressurizes gas around an
adsorbent
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a f ...
media to selectively adsorb certain components of a gas, allowing others to be selectively discarded.
Vacuum swing adsorption
Vacuum swing adsorption (VSA) uses the same principle as PSA but swings between
vacuum
A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often dis ...
pressures and
atmospheric pressure
Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, 7 ...
. The two techniques may be combined and are called "vacuum pressure swing adsorption" (VPSA) in this case.
Temperature swing adsorption
Temperature swing adsorption (TSA) uses a similar technique to other swing adsorption techniques but cycles temperature instead of pressure.
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.
See also
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* {{annotated link, Solid sorbents for carbon capture
Analytical chemistry
Industrial gases
Gas technologies