Patent GB-800851-A (GB)
Title: Dual temperature isotope exchange process
IPC: B01D59/32
Filed: 1946-05-10
Abstract: <PICT:0800851/III/1> Deuterium-enriched hydrogen or cyclohexane is produced by flowing cyclohexane and hydrogen in countercurrent successively through two exchange units, while maintaining the two units at different temperatures and intimately mixing the cyclohexane and hydrogen therein to effect transfer of deuterium from hydrogen to cyclohexane in the colder unit and from cyclohexane to hydrogen in the hotter unit.  Hydrogen containing the natural abundance of deuterium enters high temperature packed tower 12 and passes thence through 18 to low-temperature packed tower 10, whence it is with drawn at 26.  Cyclohexane enters tower 10, which is at 100 DEG  C., at 20 and flows thence through 16 to tower 12, which is at 250 DEG C., where cyclohexane is decomposed to benzene.  The system is at 100 atm. to retain the cyclohexane and benzene as liquids, and catalysts, e.g. active nickel, platinum on activated coconut charcoal, or heavy metal chromites, may be present.  The cyclohexane passes through pipe 22 to hydrogenator 24, where benzene is converted to cyclohexane by deuterium-poor hydrogen from 26 in the presence of nickel or platinum catalysts mentioned above at 100 DEG  C., and is returned to tower 10.  Preferably, a plurality of exchange systems are used, and enriched hydrogen is withdrawn from 18 at 30 and passed through high-temperature tower 32, low-temperature tower 36 and hydrogenator 38, which are the same as, and work under the same conditions as, towers 10, 12, and hydrogenator 24, while cyclohexane passes in a closed circuit through the system.  Deuterium-poor hydrogen is returned to inlet 14 to the first system, and enriched hydrogen may be withdrawn at 42 to further exchange systems.  Alternatively, the hydrogen may flow in a closed cycle, when enriched cyclohexane is withdrawn from 16 and advanced from unit to unit.  The system may alternatively be worked at atmospheric pressure, when the towers and hydrogenator contain a mixture of hydrogen and vapours of cyclohexane and/or benzene, and the mixture leaving each tower is cooled to condense and separate the organic vapours which are re-vaporized before entry into the next tower.ALSO:<PICT:0800851/IV (b)/1> Deuterium-enriched hydrogen or cyclohexane is produced by flowing cyclohexane and hydrogen in countercurrent successively through two exchange units, while maintaining the two units at different temperatures and intimately mixing the cyclohexane and hydrogen therein to effect transfer of deuterium from hydrogen to cyclohexane in the colder unit and from cyclohexane to hydrogen in the hotter unit.  Hydrogen containing the natural abundance of deuterium enters high temperature packed tower 12 and passes thence through 18 to low temperature packed tower 10, whence it is withdrawn at 26. Cyclohexane enters tower 10, which is at 100 DEG  C., at 20 and flows thence through 16 to tower 12, which is at 250 DEG  C., where cyclohexane is decomposed to benzene.  The system is at 100 atm. to retain the cyclohexane and benzene as liquids, and catalysts, e.g. active nickel, platinum on activated coconut charcoal, or heavy metal chromites, may be present.  The cyclohexane passes through pipe 22 to hydrogenator 24, where benzene is converted to cyclohexane by deuterium-poor hydrogen from 26 in the presence of nickel or platinum catalysts mentioned above at 100 DEG  C., and is returned to tower 10.  Preferably, a plurality of exchange systems are used, and enriched hydrogen is withdrawn from 18 at 30 and passed through high-temperature tower 32, low temperature tower 36 and hydrogenator 38, which are the same as, and work under the same conditions as, towers 10, 12, and hydrogenator 24, while cyclohexane passes in a closed circuit through the system.  Deuterium-poor hydrogen is returned to inlet 14 to the first system, and enriched hydrogen may be withdrawn at 42 to further exchange systems.  Alternatively, the hydrogen may flow in a closed cycle, when enriched cyclohexane is withdrawn from 16 and advanced from unit to unit.  The system may alternatively be worked at atmospheric pressure, when the towers and hydrogenator contain a mixture of hydrogen and vapours of cyclohexane and/or benzene, and the mixture leaving each tower is cooled to condense and separate the organic vapours which are re-vaporized before entry into the next tower.