WO1995032169A1 - Recuperation amelioree de fluorocarbone dans un processus d'hydrodeshalogenation - Google Patents

Recuperation amelioree de fluorocarbone dans un processus d'hydrodeshalogenation Download PDF

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Publication number
WO1995032169A1
WO1995032169A1 PCT/US1994/005654 US9405654W WO9532169A1 WO 1995032169 A1 WO1995032169 A1 WO 1995032169A1 US 9405654 W US9405654 W US 9405654W WO 9532169 A1 WO9532169 A1 WO 9532169A1
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WO
WIPO (PCT)
Prior art keywords
hydrogen
halocarbon
composition
semi
permeable membrane
Prior art date
Application number
PCT/US1994/005654
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English (en)
Inventor
Kung Hsing Lee
Original Assignee
E.I. Du Pont De Nemours And Company
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 E.I. Du Pont De Nemours And Company filed Critical E.I. Du Pont De Nemours And Company
Priority to PCT/US1994/005654 priority Critical patent/WO1995032169A1/fr
Publication of WO1995032169A1 publication Critical patent/WO1995032169A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/23—Preparation of halogenated hydrocarbons by dehalogenation
    • 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
    • C07C17/389—Separation; Purification; Stabilisation; Use of additives by adsorption on solids
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/582—Recycling of unreacted starting or intermediate materials

Definitions

  • This invention relates to the separation of hydrofluorocarbons from hydrogen.
  • CFCs chlorofluorocarbons
  • Air conditioning, refrigeration, food preservation, medical technology, and electronics are some of the areas wherein CFCs have contributed to advancements.
  • CFCs have been suspected of being largely responsible for the depletion of the stratospheric ozone layer.
  • the importance of CFCs in modern technology is such that alternatives to the presently-used CFCs are necessary and are being sought.
  • the substitute compounds must also have stability characteristics such that none or very lit * ' of them will survive to reach the stratosphere to participate in the ozone dep.-vtion process. It is generally believed that hydrogen-containing halocarbons containing fluorine and with little or no chlorine substituent will have the required stability characteristics.
  • One such compound for example, is the hydrogen-containing fluorocarbon 1,1,1,2-tetrafluoroethane, CF 3 CH 2 F (HFC- 134a), which may be an alternative to dichlorodifluoromethane, CCI 2 F 2 (CFC-12), which is widely used as a refrigerant in air conditioners, refrigerators, and the like.
  • hydrodechlorination process is meant a process wherein a chlorine-containing halocarbon is reacted with elemental hydrogen to replace one or more chlorine substituents on the halocarbon with hydrogen substituent.
  • Hydrodechlorination processes may be illustrated by using the reparation of the above-mentioned CF3CH 2 F as an example:
  • hydrodechlorination process can be used to produce hydrogen-containing fluorocarbons (HFCs) or hydrogen containing chlorofluorocarbons (HCFCs)
  • HFCs hydrogen-containing fluorocarbons
  • HCFCs hydrogen containing chlorofluorocarbons
  • economics of commercial processes and environmental concerns require that unreacted reactants be recycled for efficient utilization, the desired products be recovered as efficiently as possible, and the waste streams be minimized and disposed of with minimal environmental impact.
  • the underlying problems in the hydrodechlorination process arise from the fact that a large excess of hydrogen is usually used to provide sufficiently high yields of the desired products as well as to increase the reaction rates.
  • most industrial processes for the recovery of low boiling products involve compression/condensation, wherein under elevated pressures and cooling, a condensed liquid phase is obtained which can then be subjected to fractional distillation.
  • a process of hydrodechlorination with elemental hydrogen of a first halocarbon containing at least one chlorine substituent to form a reaction stream comprising a second halocarbon with at least one more hydrogen substituent than the first halocarbon and unreacted hydrogen comprising the steps of contacting at least a part of the reaction stream with a semi-permeable membrane with greater permeability to hydrogen compared to the permeability to the second halocarbon to provide a first composition enriched in hydrogen and a second composition depleted in hydrogen and recovering the second halocarbon from said second composition.
  • Figure 1 depicts an embodiment of the present invention in which a mixture of hydrogen and a halocarbon to be hydrodechlorinated is introduced into a reactor (A) and then a portion of the reaction product stream which is not condensed in compression/condensation system (D) is directed to one or more permaselective separator units (F and F) for separation of hydrohalocarbo ⁇ s from hydrogen.
  • A a reactor
  • D compression/condensation system
  • F and F permaselective separator units
  • Hydrodechlorination reactions may be carried out at any convenient pressure, atmospheric or superatmospheric, but are generally carried out at superatmospheric pressure. Reaction temperatures are generally in the range of from about 100°C to about 600°C, usually from about 200°C to about 400 O C
  • the reaction stream is compressed and cooled to liquefy the condensables so that fractional distillation to recover the desired product as well as any unreacted reactants for recycling can be carried out.
  • the present invention is directed to an improvement in the hydrodechlorination process wherein the desired products as well as the unreacted reactants are recovered more efficiently and waste streams minimized.
  • a mixture of hydrogen and a halocarbon to be hydrodechlorinated (e.g. CF 3 CHCIF or CF 3 CCI2F) is introduced into the reactor (A) which is maintained under the appropriate hydrodechlorination reaction conditions.
  • the reaction products exit the reactor (A) via line (2).
  • the reaction stream may be sent directly into the compression/condensation system (D) or, if desired, the reaction stream may be treated to remove acidic by-products such as hydrogen chloride and hydrogen fluoride by introducing the reaction stream into a washer (B) via line (3).
  • the washing may be with water or with alkaline water.
  • reaction stream is dried by introduction into a dryer (C) via line (4).
  • the washed and dried reaction stream exits the dryer (C) via line (5) and then into a compression/condensation system (D) wherein the reaction stream may be subjected to elevated pressures and cooled for example, 280 psia pressure and a temperature of about -30°C.
  • the condensed portion of the reaction product stream is taken from (D) via line (6) to a purification system (E) e.g. fractional distillation system whereby the desired product e.g. CF 3 CH 2 F is recovered via line (7).
  • purification system e.g. fractional distillation system
  • the portion of the reaction product stream which is not condensed in the compression/condensation system (D) contains a large amount of hydrogen and halocarbons and is of very low dew point. Disposal of this non-condensable composition e.g. by burning will constitute loss of valuable products and reactants and will aggravate the waste disposal problems.
  • the non-condensable phase from the compression/condensation system (D) is taken via line (8) and introduced into a permaselective membrane separation unit (F) using a permaselective membrane which provides selective permeation for hydrogen.
  • the essentially pure hydrogen is taken via line (9) from the membrane separator (F) into line (15) where the recovered hydrogen is recycled into the reactor (A) via line (1).
  • the hydrogen-depleted mixture from the separator (F) now with much higher dew point, is taken via lines (10) and (11) back to the compression/condensation system (D).
  • the hydrogen-depleted mixture from the separator (F) may be taken via line (12) to another permaselective separator (F') with a permaselective separation membrane which provides selective permeation for hydrogen.
  • Essentially pure hydrogen from the separator (F) may be taken via line (13) to line (15) and thence back to the reactor (A).
  • the non-permeate from the separator (F), which is now even more depleted in hydrogen, is taken via line (14) back to the compression/condensation system (D) for processing and then to the purification unit (E) to recover the desired product and the unreacted reactants.
  • the effectiveness of the permaselective separation process depends upon the permaselective membranes which allow for the selective permeation of hydrogen through the membranes. Any membrane composition which is capable of selectively allowing the passage of hydrog n versus halocarbons is useful in the present invention. More particularly, it ..as been found that membranes of polysubstituted aromatic polyamides provide the desired selective permeation of hydrogen in compositions comprising hydrogen and halocarbons.
  • These asymmetric polyamides are polyaromatic amides wherein the diamine component of at least one polyaromatic component comprises an aromatic polyamide containing the repeating unit
  • R is an alkyl group of 1 to 3 carbon atoms
  • R' is R or H and Y is H, CH3 or CF3 and where Ar' is
  • the semi-permeable membrane separation unit useful in the present invention can be generally any such devices as are well known in the art incorporating the semi-permeable membranes as thin layer films, spiral wound membranes, hollow fiber semi-pe ⁇ neable membranes or the like.
  • the usual operating parameters for the semi-permeable membrane separation systems such as higher pressures on the feed side of the membranes than on the permeate side of the membranes, temperature variations and the like are known in the art and may be used to increase effectiveness .
  • the temperature may be from 0°C to 300°C
  • the pressure differential between the feed side and the permeate side of the semi- permeable membrane may range from 1 to 30 atmospheres
  • the concentration of hydrogen in the permeate stream may be varied by varying the residence time of the permeate stream or reaction stream in relation to their respective sides of the semi-permeable membrane.
  • the present invention provides significant improvements in the hydrodehalogenation processes. While the present improvement process is described in terms of treating a part of the reaction stream of a hydrodechlorination process, the present process is equally applicable for the separation of any composition containing hydrogen and halocarbons.
  • a typical reaction product stream from the reaction of 1,1,1,2-tetrafluorodichloroethane (CF3CCI2F) with hydrogen to produce 1,1,1,2-tetrafluoroethane (CF3CH 2 F) was washed with water and alkaline water to remove hydrogen chloride and hydrogen fluoride.
  • the washed reaction product stream was then dried, and subjected to a pressure of about 280 psia and a temperature of about -30°C .
  • the condensed liquid phase was recovered and subjected to fractional distillation to obtain the desired product CF 3 CH 2 F, and the unreacted CF 3 CCI 2 F and the partially hydrodechlorinated product CF 3 CHCIF for recycling.
  • the "Residue” (shown in Table I) contained 14 mole percent organics and had considerably higher dew point (about 0°C).
  • the "Residue” can be contacted with still another permeation separation unit for even greater concentration of the organics and, thus, obtain increased dew point and recovery of halocarbons.

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

Abstract

L'invention se rapporte à un procédé d'hydrodéchloruration par l'hydrogène élémentaire d'un premier halocarbone contenant au moins un substituant du chlore afin d'obtenir un courant de réaction comprenant un second halocarbone pourvu d'au moins un substituant d'hydrogène de plus que le premier. Cette amélioration consiste à mettre en contact une partie du courant de réaction du processus d'hydrodéchloruration avec une membrane semi-perméable qui confère une plus grande perméabilité à l'hydrogène afin d'obtenir une première composition enrichie en hydrogène et une seconde composition appauvrie en hydrogène, et à récupérer le second halocarbone à partir de cette seconde composition.
PCT/US1994/005654 1994-05-19 1994-05-19 Recuperation amelioree de fluorocarbone dans un processus d'hydrodeshalogenation WO1995032169A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US1994/005654 WO1995032169A1 (fr) 1994-05-19 1994-05-19 Recuperation amelioree de fluorocarbone dans un processus d'hydrodeshalogenation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1994/005654 WO1995032169A1 (fr) 1994-05-19 1994-05-19 Recuperation amelioree de fluorocarbone dans un processus d'hydrodeshalogenation

Publications (1)

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WO1995032169A1 true WO1995032169A1 (fr) 1995-11-30

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998050332A1 (fr) * 1997-05-02 1998-11-12 E.I. Du Pont De Nemours And Company Extraction de co2 dans les composes fluores insatures par membrane semipermeable
WO1998050331A1 (fr) * 1997-05-02 1998-11-12 E.I. Du Pont De Nemours And Company Elimination du co2 dans les fluorocarbures par membrane semipermeable
US8911641B2 (en) 2010-05-20 2014-12-16 Mexichem Amanco Holding S.A. De C.V. Heat transfer compositions
WO2023118694A1 (fr) * 2021-12-23 2023-06-29 Arkema France Procede de production et de purification du trifluoroethylene

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0219878A2 (fr) * 1985-10-24 1987-04-29 E.I. Du Pont De Nemours And Company Procédé de séparation de gaz et membrane
US5196616A (en) * 1991-10-18 1993-03-23 E. I. Du Pont De Nemours And Company Process for separating and recovering fluorocarbons and hydrogen fluoride from mixtures thereof

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0219878A2 (fr) * 1985-10-24 1987-04-29 E.I. Du Pont De Nemours And Company Procédé de séparation de gaz et membrane
US5196616A (en) * 1991-10-18 1993-03-23 E. I. Du Pont De Nemours And Company Process for separating and recovering fluorocarbons and hydrogen fluoride from mixtures thereof

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998050332A1 (fr) * 1997-05-02 1998-11-12 E.I. Du Pont De Nemours And Company Extraction de co2 dans les composes fluores insatures par membrane semipermeable
WO1998050331A1 (fr) * 1997-05-02 1998-11-12 E.I. Du Pont De Nemours And Company Elimination du co2 dans les fluorocarbures par membrane semipermeable
US6123749A (en) * 1997-05-02 2000-09-26 E. I. Du Pont De Nemours And Company Separation of CO2 from unsaturated fluorinated compounds by semipermeable membrane
US6156097A (en) * 1997-05-02 2000-12-05 E. I. Du Pont De Nemours And Company CO2 removable from fluorocarbons by semipermeable membrane
US8911641B2 (en) 2010-05-20 2014-12-16 Mexichem Amanco Holding S.A. De C.V. Heat transfer compositions
WO2023118694A1 (fr) * 2021-12-23 2023-06-29 Arkema France Procede de production et de purification du trifluoroethylene
FR3131305A1 (fr) * 2021-12-23 2023-06-30 Arkema France Procédé de production et de purification du trifluoroéthylène

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