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WO1996006063A1 - Purification du pentafluoroethane - Google Patents

Purification du pentafluoroethane Download PDF

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Publication number
WO1996006063A1
WO1996006063A1 PCT/GB1995/001873 GB9501873W WO9606063A1 WO 1996006063 A1 WO1996006063 A1 WO 1996006063A1 GB 9501873 W GB9501873 W GB 9501873W WO 9606063 A1 WO9606063 A1 WO 9606063A1
Authority
WO
WIPO (PCT)
Prior art keywords
pentafluoroethane
liquid
organic compound
polar organic
cfc
Prior art date
Application number
PCT/GB1995/001873
Other languages
English (en)
Inventor
Paul Nicholas Ewing
Gary Goodyear
Mark Fitchett
James Malcolm Forsyth
Original Assignee
Imperial Chemical Industries Plc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Imperial Chemical Industries Plc filed Critical Imperial Chemical Industries Plc
Publication of WO1996006063A1 publication Critical patent/WO1996006063A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/38—Separation; Purification; Stabilisation; Use of additives
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/38—Separation; Purification; Stabilisation; Use of additives
    • C07C17/383—Separation; Purification; Stabilisation; Use of additives by distillation
    • C07C17/386—Separation; Purification; Stabilisation; Use of additives by distillation with auxiliary compounds

Definitions

  • This invention relates to a process for the purification of pentafluoroethane (HFC 125) and particularly to a process for removing chloropentafluoroethane (CFC 115) from mixtures of HFC 125 and CFC 115 to provide essentially pure pentafluoroethane. It has been proposed to manufacture HFC 125 by hydrogenation of CFC 115 in the gas phase at elevated temperature in the presence of a hydrogenation catalyst or by hydrofluorination of perchloroethylene or dichloro-l,l,l-trifluoroethane (HCFC 123) over a fluorination catalyst.
  • HFC 125 pentafluoroethane
  • CFC 115 chloropentafluoroethane
  • HFC 125 containing impurities and in particular the impurity CFC 115 which may be present in an amount of up to 20% or more and which needs to be removed from HFC 125 which is to be used as or as a component of refrigerant compositions.
  • a process for the purification of pentafluoroethane by removing chloropentafluoroethane therefrom which comprises contacting the impure pentafluoroethane in the gas phase with a liquid, polar organic compound selected from oxygen- and/or nitrogen-containing compounds and halogenated hydrocarbons to form a liquid phase enriched in pentafluoroethane and a gas phase depleted in pentafluoroethane, separating the liquid phase containing pentafluoroethane from the gas phase and recovering essentially pure pentafluoroethane from the liquid phase.
  • the organic compound preferably has a boiling point at least 20°C higher than the boiling point of pentafluoroethane so that recovery of pentafluoroethane from the liquid phase can be effected by simple distillation under reflux conditions at a pressure of up to 15 barg to remove pentafluoroethane as a gaseous top stream for collection and the organic compound as a liquid bottom stream which can be re-used in the treatment of impure pentafluoroethane.
  • the organic compound is recycled to the extraction stage of the process.
  • the organic compound hereinafter referred to as the extractant is liquid under the conditions of use and is polar.
  • Compounds of high polarity are preferred and in particular compounds having dipole moments in excess of 1 Debye, preferably greater than 1.5 and especially preferably greater than 2 Debye.
  • oxygen and/or nitrogen containing compounds may be used as the extractant, including saturated and unsaturated aliphatic compounds and aromatic compounds.
  • the aliphatic compound may be straight-chain or branched-chain and it may be cyclic or acyclic.
  • suitable compounds of this type include alcohols, aldehydes, ketones, nitriles, acids, acid anhydrides, furans, ethers, esters and compounds of mixed functionality such as partially fluorinated ethers. Mixtures of organic compounds may be used if desired.
  • extractants of this type are acetone, methyl isobutyl ketone [MIBK], tetrahydrofuran, propionaldehyde, acetonitrile, diethyl ether and ethanoic anhydride.
  • MIBK methyl isobutyl ketone
  • the boiling point of the extractant may vary over a wide range providing the extractant is liquid under the conditions of use. Compounds of boiling point above 100°C may be used. Any halogenated hydrocarbon can be used as the extractant which is liquid and polar and selectively dissolves pentafluoroethane from the mixture being treated.
  • the compound will contain at least two fluorine atoms, preferably at least three fluorine atoms and may contain one or more halogen atoms other than fluorine, notably chlorine atoms.
  • hydrofluorocarbons and hydrochlorofluorocarbons containing 2 to 4 carbon atoms are especially preferred.
  • An example of a suitable hydrofluorocarbon is 1,1,2-trifluoroethane (HFC 143).
  • An example of a suitable compound of mixed functionality is bis(fluoromethyl) ether.
  • the extraction stage of the process may be carried out by passing the gaseous mixture over or through the liquid extractant but we prefer to pass the gaseous phase and the liquid in countercurrent through a column. In particular, we prefer to pass the gaseous phase upwardly through a column down which is flowing the liquid phase.
  • the extraction stage can be carried out at any temperature up to the boiling point of the liquid extractant. Room temperature can be conveniently used providing the extractant is liquid at this temperature.
  • the pressure may be atmospheric, subatmospheric or superatmospheric pressure, the latter being preferred. Pressures up to 20 barg are useable although we prefer pressures below about 10-12 barg.
  • the amount of the extractant used preferably should be sufficient to extract substantially all of the pentafluoroethane from the mixture in a single pass through the column and is dependent upon the efficiency of the extraction. Usually an excess of the extractant will be used, typically a molar ratio of extractant: pentafluoroethane in the range 3: 1 to 100: 1.
  • FIG. 1 of the accompanying drawings shows a flow sheet for a continuous process for the purification of pentafluoroethane.
  • a gaseous stream 1 comprising a mixture of HFC 125 and CFC 115 is fed to the middle portion of a distillation column 2 into the top portion of which is fed a liquid extractant such as acetone, stream 3.
  • the gaseous feed flows upwardly through the column countercurrent to the liquid extractant and HFC 125 is extracted from the gas into the liquid.
  • CFC 115 is withdrawn from the top of the column, stream 4, and the liquid extractant now containing pentafluoroethane is withdrawn from the bottom of the column, stream 5.
  • the liquid stream 5 containing pentafluoroethane is fed to the middle portion of a second distillation column 6 in which the liquid is distilled under reflux conditions to boil off the entrained pentafluoroethane which is removed from the top of the column as stream 7 and collected.
  • the liquid extractant stream 8 withdrawn from the bottom of the column 6 is recycled as stream 3 to the top of the first distillation column 2 for re-use to extract pentafluoroethane from the feed stream 1.
  • the process according to the invention is useful for the treatment of any mixture of pentafluoroethane and CFC 115 to recover the pentafluoroethane in essentially pure form.
  • the process is particularly useful for treating the product stream obtained during the manufacture of pentafluoroethane.
  • Such a product stream typically contains other impurities in addition to CFC 115 and it will usually be treated to remove some at least of such other impurities before it is treated according to the present invention.
  • the product stream may be treated to remove hydrogen chloride and hydrogen fluoride (eg scrubbed with water or sodium hydroxide solution to remove hydrogen chloride and hydrogen fluoride), dried, distilled to remove low-boiling compounds and further distilled to separate the pentafluoroethane CFC115 mixture from high-boiling compounds before the pentafluoroethane/CFC 115 mixture is treated with the extractant.
  • a flow sheet for a process including these pre-treatments is shown in Figure 2.
  • the product stream 9 from the gas phase hydrofluorination of perchloroethylene to produce pentafluoroethane is fed to the middle portion of a distillation column 10 from which a fraction 11 comprising low-boiling compounds or lights is withdrawn at the top and the remainder 12 containing high-boiling compounds or heavies is withdrawn from the bottom.
  • the stream 12 is fed to the top portion of a distillation column 13 from which the heavies 14 are withdrawn at the bottom and a mixture 15 of pentafluoroethane and CFC 115 is withdrawn from the top.
  • the mixture 15 is then fed as stream 1 to the process shown in Figure 1.
  • a vapour mixture of CFC 115 (1 ml) and HFC 125 (9 ml) were added to an evacuated 1 0 ml round-bottom flask fitted with a tap, a septum and a magnetic stirrer. The flask was returned to atmospheric pressure by addition of air and an additional 13 ml of air was added to create a slight positive pressure in the flask.
  • a sample (5 ml) of the vapours in the flask was removed and analysed by gas chromatography to determine the initial composition of the mixture of HFC 125 and CFC 115. This procedure was repeated 16 times; the average of the results gave an initial composition of the mixture of 12.4 mole% CFC 115 and 87.49 mole% HFC 125.
  • the range of HFC 125 contents was from 86.18 mole% to 87.56 mole%.
  • Solubility (1) Solubility of CFC 115 in mole fraction x 10 2 .
  • Solubility (2) Solubility of HFC 125 in mole fraction x 10 "2 .
  • a vapour mixture of 70 mis HFC 125 and 70 mis CFC 115 was added to an evacuated 160 ml flask. The flask was let up to atmospheric pressure and then an additional 20 mis of air was added to generate a slight positive pressure in the flask. A 5 ml vapour sample was removed and analysed by gas chromatography to determine the initial vapour concentration of the fluorocarbons. 5 mis of liquid bis(fluoromethyl) ether [BFME] was added and the mixture was stirred at 0°C for 30 minutes after which time a 5 ml sample was removed from the headspace and analysed by Gas Chromatography to determine the final vapour concentration.
  • BFME liquid bis(fluoromethyl) ether
  • HFC 125 is significantly more soluble than CFC 115 in BFME.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention concerne un procédé de purification du pentafluoroéthane par élimination du chloropentafluoroéthane qu'il renferme. Le pentafluoroéthane impur en phase gazeuse est mis en contact avec un composé organique polaire liquide agissant comme agent extracteur qui, de préférence, circule à contre-courant dans une colonne, pour former une phase liquide contenant le pentafluoroéthane à partir de laquelle est récupéré du pentafluoroéthane pratiquement pur, de préférence par distillation simple au reflux. Le composé organique polaire liquide peut être un composé renfermant de l'oxygène et ou de l'azote ou bien un hydrocarbure halogéné.
PCT/GB1995/001873 1994-08-24 1995-08-08 Purification du pentafluoroethane WO1996006063A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9417118.8 1994-08-24
GB9417118A GB9417118D0 (en) 1994-08-24 1994-08-24 Purification of pentafluoroethane

Publications (1)

Publication Number Publication Date
WO1996006063A1 true WO1996006063A1 (fr) 1996-02-29

Family

ID=10760345

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1995/001873 WO1996006063A1 (fr) 1994-08-24 1995-08-08 Purification du pentafluoroethane

Country Status (3)

Country Link
GB (1) GB9417118D0 (fr)
WO (1) WO1996006063A1 (fr)
ZA (1) ZA956809B (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998015511A1 (fr) * 1996-10-10 1998-04-16 Alliedsignal Inc. Procede de separation de pentafluoroethane et de chloropentafluoroethane
WO1998052889A1 (fr) * 1997-05-22 1998-11-26 Daikin Industries, Ltd. Procede de preparation de pentafluoroethane
US6039845A (en) * 1997-01-06 2000-03-21 Elf Atochem S.A. Process for the purification of pentafluoroethane by extractive distillation
EP1026139A4 (fr) * 1997-08-21 2001-06-13 Daikin Ind Ltd Procede de preparation de pentafluoroethane
US7060165B2 (en) 2002-02-14 2006-06-13 Pcbu Services, Inc. Processes for purification and production of fluorocarbons
WO2007013680A1 (fr) * 2005-07-28 2007-02-01 Showa Denko K.K. Procede pour extraire du pentafluoroethane, et methode de production de pentafluoroethane impliquant le procede susmentionne
WO2016166045A1 (fr) 2015-04-14 2016-10-20 Arkema France Procede de purification du pentafluoroethane

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1468451B1 (de) * 1963-10-25 1970-01-15 Onoda Cement Co Ltd Verfahren zur Abtrennung von Perfluoraethan,Perfluorpropan,Tetrafluoraethylen,Hexafluorpropylen,Perfluorcyclobutan aus ihren Gemischen mit bestimmten Fluorkohlenwasserstoffen
US5087329A (en) * 1991-05-16 1992-02-11 E. I. Du Pont De Nemours And Company Process for separating pentafluoroethane from a mixture of halogenated hydrocarbons containing chloropentafluoroethane
EP0626362A1 (fr) * 1993-05-25 1994-11-30 Showa Denko Kabushikikaisha Procédé de purification de pentafluoroéthane

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1468451B1 (de) * 1963-10-25 1970-01-15 Onoda Cement Co Ltd Verfahren zur Abtrennung von Perfluoraethan,Perfluorpropan,Tetrafluoraethylen,Hexafluorpropylen,Perfluorcyclobutan aus ihren Gemischen mit bestimmten Fluorkohlenwasserstoffen
US5087329A (en) * 1991-05-16 1992-02-11 E. I. Du Pont De Nemours And Company Process for separating pentafluoroethane from a mixture of halogenated hydrocarbons containing chloropentafluoroethane
EP0626362A1 (fr) * 1993-05-25 1994-11-30 Showa Denko Kabushikikaisha Procédé de purification de pentafluoroéthane

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998015511A1 (fr) * 1996-10-10 1998-04-16 Alliedsignal Inc. Procede de separation de pentafluoroethane et de chloropentafluoroethane
US6039845A (en) * 1997-01-06 2000-03-21 Elf Atochem S.A. Process for the purification of pentafluoroethane by extractive distillation
WO1998052889A1 (fr) * 1997-05-22 1998-11-26 Daikin Industries, Ltd. Procede de preparation de pentafluoroethane
US6175045B1 (en) 1997-05-22 2001-01-16 Daikin Industries Ltd. Process for the preparation of pentafluoroethane
JP4529287B2 (ja) * 1997-08-21 2010-08-25 ダイキン工業株式会社 ペンタフルオロエタンの製造方法
EP1026139A4 (fr) * 1997-08-21 2001-06-13 Daikin Ind Ltd Procede de preparation de pentafluoroethane
US6527917B1 (en) 1997-08-21 2003-03-04 Daikin Industries Ltd. Process for preparing pentafluoroethane
US7060165B2 (en) 2002-02-14 2006-06-13 Pcbu Services, Inc. Processes for purification and production of fluorocarbons
JP2007031382A (ja) * 2005-07-28 2007-02-08 Showa Denko Kk ペンタフルオロエタンの回収方法および該方法を含むペンタフルオロエタンの製造方法
KR100895172B1 (ko) * 2005-07-28 2009-05-04 쇼와 덴코 가부시키가이샤 펜타플루오로에탄의 회수 방법 및 상기 방법을 포함하는펜타플루오로에탄의 제조 방법
WO2007013680A1 (fr) * 2005-07-28 2007-02-01 Showa Denko K.K. Procede pour extraire du pentafluoroethane, et methode de production de pentafluoroethane impliquant le procede susmentionne
US8003832B2 (en) 2005-07-28 2011-08-23 Showa Denko K.K. Process for recovering pentafluoroethane, and production method of pentafluoroethane involving the process
WO2016166045A1 (fr) 2015-04-14 2016-10-20 Arkema France Procede de purification du pentafluoroethane
US9975825B1 (en) 2015-04-14 2018-05-22 Arkema France Process for the purification of pentafluoroethane

Also Published As

Publication number Publication date
GB9417118D0 (en) 1994-10-12
ZA956809B (en) 1996-02-26

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