Rare Noble Gases: Production and Use of Ne, Kr and Xe
By Jim Dray, JRD GasTech LLC |
Rare noble gases neon, krypton and xenon have unique properties and can be obtained from air, but the economics of isolating them at air-separation units depends on demand and pricing. This article provides information on their production and use
The term “rare gases” typically refers to the elements neon (Ne), krypton (Kr) and xenon (Xe). They are noble gases that are collected and separated by cryogenic separation of air, the primary method of producing two of the world’s largest commercial chemicals (oxygen and nitrogen). The concentration in air of Ne, Kr and Xe total less than 20 parts per million (ppm). Argon (Ar) is also a noble gas recovered from air, but its concentration in air is comparatively much higher (0.93%) and is not considered rare. Helium (He) is present at about 5 ppm in air, but is much more easily recovered from certain natural gas deposits, and is not usually commercially recovered from air. All noble gases lighter than radon (He, Ne, Ar, Kr and Xe) are valued for their inertness and other unique properties. This article provides information about the separation of Ne, Kr and Xe from air and their respective uses.
Basics of air separation
Clean, dry air is made up of approximately 78% nitrogen and 21%…