Krypton separation

Hutter, E.J., R.Von Ammon, W.Bumiller, amd G.Neffe. 1986. Final results and consequences of the development of a cryogenic krypton separation system. Proceedings of the 19th DOE/NRC Nuclear Air Cleaning Conference, Seattle, WA, Aug 18-21. 

Ryan P, Farha OK, Broadbelt LJ, Snurr RQ Computational screening of metal-organic frameworks for xenon/krypton separation, AIChEJ 57(7) 1759—1766, 2011. 

The latest of three ethylene recovery plants was started in 1991. Sasol sold almost 300,000 t of ethylene in 1992. Sasol also produces polypropylene at Secunda from propylene produced at Sasol Two. In 1992 Sasol started constmction of a linear alpha olefin plant at Secunda to be completed in 1994 (40). Initial production is expected to be 100,000 t/yr pentene and hexene. Sasol also has a project under constmction to extract and purify krypton and xenon from the air separation plants at Sasol Two. Other potential new products under consideration at Sasol are acrylonitrile, acetic acid, acetates, and alkylamines. 

This krypton—xenon mixture is usually sent to a different location for separation by distillation and further purification by catalytic and/or adsorptive processes. 

Separation of krypton and xenon from spent fuel rods should afford a source of xenon, technical usage of which is continuously growing (84). As of this writing, however, reprocessing of spent fuel rods is a pohtical problem (see Nuclearreactors). Xenon from fission has a larger fraction of the heavier isotopes than xenon from the atmosphere and this may affect its usefulness in some appHcations. 

Commercially pure (< 99.997%) helium is shipped directiy from helium-purification plants located near the natural-gas supply to bulk users and secondary distribution points throughout the world. Commercially pure argon is produced at many large air-separation plants and is transported to bulk users up to several hundred kilometers away by tmck, by railcar, and occasionally by dedicated gas pipeline (see Pipelines). Normally, only cmde grades of neon, krypton, and xenon are produced at air-separation plants. These are shipped to a central purification faciUty from which the pure materials, as well as smaller quantities and special grades of helium and argon, are then distributed. Radon is not distributed commercially. 

The U.S. production of argon is summarized in Table 5. Because argon is a by-product of air separation, its production is ca 1% that of air feed. Total 1988 United States consumption of neon, krypton, and xenon was 36,400, 6,800, and 1,200 m, respectively (88). 

The hydrogen atom orbitals give us the numbers 2, 8, 18, and 32—the numbers we find separating the specially stable electron populations of the inert gases. It was necessary to multiply n2 by two—an important factor that could not have been anticipated. Furthermore, it will be necessary to find an explanation for the occurrence of eight-electron differences both at neon and at argon and eighteen-electron differences both at krypton and at xenon. 

There is little evidence for 1 1 compounds between elements in this group under normal conditions. The diatomic van der Waals molecules, CaMg, SrMg and SrCa, however, have been synthesized by codepositing the atoms from separate sources with argon or krypton into solid matrices at 12 K. These low-T species are identified from their laser-induced fluorescence spectra. The ground-state spectroscopic data for these alkaline-earth dimers form a sensible series between the parent molecules Mg2, Caj and Sr2. ... 

Eastwood, T. A., Brown, F., and Crocker, I. H., "A krypton-81 half-life determination using a mass separator", Nucl. Phys., 1964, 58, 328. 

Air separation industry, U.S., 27 754 Air-separation plants, 27 359, 750-751 Air-separation units, krypton and xenon recovery from, 2 7 362 Air-slaked lime, 15 26 Air slaking, 25 43 Air sparging... 

Krypton fluorocationic salts, 17 333 Krypton lasers, 14 684. See also KrF laser in laser light shows, 14 688 Krypton-xenon, purification and separation of, 17 361-362 Krypton-xenon column, 17 359, 360 Kubelka-Munk equation, 7 317-318 14 231 23 127... 

Lewis RS (1975) Rare gases in separated whitlockite from the St Severin chondrite xenon and krypton from fission of extinct Pu. Geochim Cosmochim Acta 39 417-432 Lewis RS, Srinivasan B, Anders E (1975) Host phase of a strange xenon component in Allende. Science 190 1251-1262... 

Most krypton produced in commercial scale comes from air. Krypton and other inert gases are obtained from air by a distdlation-hquefaction process. Different types of air-separation plants varying in design are known for commercial production of nitrogen, oxygen, and inert gases (See Hehum). 

Xenon is recovered from air by liquefaction and fractional distillation. Usually it is obtained as a by-product of making other noble gases. It is collected in the liquid oxygen fraction along with krypton, acetylene, and other hydrocarbons that may be present in air. The xenon fraction is flash vaporized. Hydrocarbons present are separated by burning over a catalyst. Xenon is absorbed on silica gel at low temperatures. Finally, it is separated from krypton by selective absorption and desorption from charcoal. 

With the aid of a new liquid-air machine, generously provided by Dr. Ludwig Mond, Professor Ramsay and Dr. Travers prepared larger quantities of krypton and neon, and by repeated fractionation of krypton, a still heavier gas was separated from it, which they named xenon, the stranger (15). It was discovered on July 12, 1898. Vacuum tubes containing it show forth a beautiful blue glow. 

The difference between the two asymptotes is a decrease by a factor of 6.5 for the methane krypton system and an increase by a factor of 6.5 for the P-Q pair throughout the temperature range. Decrease in both pressure and temperature favour separation in the case of methane-krypton-5A except where the favourability is altered where the converse is true, whereas decrease in temperature but increase in pressure favour separation in the case of the P-Q pair. 

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