CA2262702A1 - Recovery of highly fluorinated carboxylic acids from the gaseous phase - Google Patents
Recovery of highly fluorinated carboxylic acids from the gaseous phase Download PDFInfo
- Publication number
- CA2262702A1 CA2262702A1 CA002262702A CA2262702A CA2262702A1 CA 2262702 A1 CA2262702 A1 CA 2262702A1 CA 002262702 A CA002262702 A CA 002262702A CA 2262702 A CA2262702 A CA 2262702A CA 2262702 A1 CA2262702 A1 CA 2262702A1
- Authority
- CA
- Canada
- Prior art keywords
- highly fluorinated
- fluorinated carboxylic
- carboxylic acids
- recovery
- solution
- Prior art date
- Legal status (The legal status 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 status listed.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/41—Preparation of salts of carboxylic acids
- C07C51/412—Preparation of salts of carboxylic acids by conversion of the acids, their salts, esters or anhydrides with the same carboxylic acid part
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
-
- 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
- Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02C20/00—Capture or disposal of greenhouse gases
- Y02C20/30—Capture or disposal of greenhouse gases of perfluorocarbons [PFC], hydrofluorocarbons [HFC] or sulfur hexafluoride [SF6]
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Treating Waste Gases (AREA)
Abstract
This invention concerns a process for recovering highly fluorinated carboxylic acids from waste gas streams in which the waste gas is brought into contact with an alkaline wash solution > 1.15 g/cm3, so that the salt of the highly fluorinated carboxylic acid precipitates as a separate phase. This process is particularly advantageous if the alkaline wash solution is a potassium carbonate solution.
Description
WO 98/05621 FILE,P~'~ ' ~ PCT/EP97/04146 Description Recovery of highly fluorinated carboxylic acids from the gas phase German Patent 195 27 276 (Patent Specification published on 08.08.1996) relates to a process for the recovery of highly fluorinated carboxylic acids from off-gas streams, wherein the off-gas is brought into contact with an alkaline washing solution of density >1.15 g/cm3 so that the salt of the highly fluorinated carboxylic acid settles out as a separate phase.
As a further development of this inventive conception, it has now been found that the alkaline washing solution used is advantageously a potassium carbonate solution.
The invention thus relates to a process for the recovery of highly fluorinated carboxylic acids from off-gas streams, in which the off-gas is brought into contact with an alkaline washing solution of density >1.15 g/cm3 so that the salt of the highly fluorinated carboxylic acid settles out as a separate phase, wherein the alkaline washing solution used is a potassium carbonate solution.
When the alkaline washing solution in the process of German Patent 195 27 276 is an alkali metal hydroxide solution, the corresponding carbonate is formed if the off-gas stream to be purified contains carbon dioxide.
It has now been found that, when using sodium hydroxide solution, this sodium carbonate leads to encrustation in the ¦3crubbing col~,~l. Thi3 folllla~i~Ll uL carb~ t ~ l~
furthermore associated with an undesirable co ~ ion of sodium hydroxide. The use of potassi ~ onate as the alkaline agent avoids these ~ sa~ ntages.
If sodium ca ~ ~ is used instead of potassium r rbo~ sodium hydroxide is consumed but there is siderable increase i~l ~Ll~rustatia~ oreuver, ., Appendix 1 to our letter dated 15.07.1998 /
/
scrubbing column. This formation of carbonate is furthermore associated with an undesirable consumption of sodium hydroxide. The use of potassium carbonate as the alkaline agent avoids these disadvantages.
If sodium carbonate is used instead of potassium carbonate, no sodium hydroxide is consumed but there is a considerable increase in encrustation. Moreover, AMENDED SHEET
CA 02262702 1999-02-04 IG~
Appendix 1 to our letter dated 15.07.1998 sodium carbonate has a less favorable solubility behavior. This is shown by the fact that the cooling of sodium carbonate solutions of the density required for the process results in precipitation due to super-saturation. This is not the case with potassium carbonate, so it is not necessary to heat pipelines and vessels.
It has further been found that when potassium carbonate is used as the alkaline agent, the potassium salt of the highly fluorinated carboxylic acid is deposited in a form which is easier to filter off than when potassium hydroxide solution is used. This is coupled with the abovementioned advantage that when potassium carbonate is used, there is no substantial consumption of alkaline agent by absorbed carbon dioxide.
The density of the alkaline washing solution is advan-tageously 1.2 to 1.4 g/cm3.
Reference is made to the main patent DE-C-195 27 276 for further details.
The invention will now be illustrated further by means of the following example.
AMENDED SHEET
Example 400 Nm3/h of off-gas from a process for drying powdered fluorinated polymer, at a temperature of 171~C, are introduced into a commercially available scrubbing column of length 2000 mm and internal diameter 250 mm. The off-gas contains 750 mg/Nm3 of perfluorooctanoic acid, corresponding to 300 g/h. Circa 20 kg/h of water are additionally conveyed with the off-gas from the dryer into the scrubbing process. The pressure in the scrubbing column is circa 1 bar absolute.
10 m3/h of an alkaline washing liquor, consisting essen-tially of aqueous potassium carbonate solution of density 1.30 g/cm3, at a temperature of 45~C, are introduced into the scrubber via a nozzle. The purified off-gas stream of 400 Nm3/h, now containing only 0.8 mg/Nm3 of perfluorooctanoic acid, corresponding to 0.32 g/h, escapes from the lower section of the scrubbing column.
Water vapor, corresponding to the water partial pressure, is additionally present at the temperature of circa 45~C
prevailing in the scrubber.
The scrubber is operated in co-current. The alkaline washing medium and the potassium salt of perfluoro-octanoic acid which is formed flow out of the column directly into a separating vessel of volume 0.4 m3, where the potassium salt of perfluorooctanoic acid, which is insoluble in the alkaline washing solution, floats to the top as a pulpy layer. The alkaline washing solution, which now contains practically no potassium salt of perfluorooctanoic acid, is withdrawn from the bottom of the separating vessel and pumped back into the scrubbing column. The concentration of dissolved potassium salt of perfluorooctanoic acid in the washing medium is about 170 mg/l. The density of the washing liquor is maintained at the desired value of about 1.30 g/cm3 by the addition of potassium carbonate. The potassium salt of perfluorooctanoic acid which has separated out as a pulpy ., , t - 4 -layer runs off into a tank through an overflow on the separating vessel, together with some washing medium.
The discharge process is aided by a very slow stirrer immersed directly in the upper layer. In the separating vessel, the separation of the washing solution and the potassium perfluorooctanoate foam formed is very good.
After standing for several hours, a further two phases separate out in the tank: a lower phase consisting essentially of excess washing liquor, and a pulpy upper phase. The lower phase is separated off and recycled into the washing process.
The pulpy upper phase contains 36% by weight of potassium perfluorooctanoate.
The concentrate obtained in this way is subjected to further working-up to give pure 100% by weight perfluorooctanoic acid.
It may be mentioned that although the concentrate obtained in this way is a stirrable and pumpable mixture, it does not constitute a stable solution of the potassium salt of perfluorooctanoic acid. To obtain a stable solution, it would be necessary to add even more water.
However, this is not absolutely necessary for further working-up.
Because the lower phase which has been separated off is recycled into the washing process as described, no perfluorooctanoic acid is lost. There is no observable impairment of the washing process due to encrustation in the column after several weeks of operation.
As a further development of this inventive conception, it has now been found that the alkaline washing solution used is advantageously a potassium carbonate solution.
The invention thus relates to a process for the recovery of highly fluorinated carboxylic acids from off-gas streams, in which the off-gas is brought into contact with an alkaline washing solution of density >1.15 g/cm3 so that the salt of the highly fluorinated carboxylic acid settles out as a separate phase, wherein the alkaline washing solution used is a potassium carbonate solution.
When the alkaline washing solution in the process of German Patent 195 27 276 is an alkali metal hydroxide solution, the corresponding carbonate is formed if the off-gas stream to be purified contains carbon dioxide.
It has now been found that, when using sodium hydroxide solution, this sodium carbonate leads to encrustation in the ¦3crubbing col~,~l. Thi3 folllla~i~Ll uL carb~ t ~ l~
furthermore associated with an undesirable co ~ ion of sodium hydroxide. The use of potassi ~ onate as the alkaline agent avoids these ~ sa~ ntages.
If sodium ca ~ ~ is used instead of potassium r rbo~ sodium hydroxide is consumed but there is siderable increase i~l ~Ll~rustatia~ oreuver, ., Appendix 1 to our letter dated 15.07.1998 /
/
scrubbing column. This formation of carbonate is furthermore associated with an undesirable consumption of sodium hydroxide. The use of potassium carbonate as the alkaline agent avoids these disadvantages.
If sodium carbonate is used instead of potassium carbonate, no sodium hydroxide is consumed but there is a considerable increase in encrustation. Moreover, AMENDED SHEET
CA 02262702 1999-02-04 IG~
Appendix 1 to our letter dated 15.07.1998 sodium carbonate has a less favorable solubility behavior. This is shown by the fact that the cooling of sodium carbonate solutions of the density required for the process results in precipitation due to super-saturation. This is not the case with potassium carbonate, so it is not necessary to heat pipelines and vessels.
It has further been found that when potassium carbonate is used as the alkaline agent, the potassium salt of the highly fluorinated carboxylic acid is deposited in a form which is easier to filter off than when potassium hydroxide solution is used. This is coupled with the abovementioned advantage that when potassium carbonate is used, there is no substantial consumption of alkaline agent by absorbed carbon dioxide.
The density of the alkaline washing solution is advan-tageously 1.2 to 1.4 g/cm3.
Reference is made to the main patent DE-C-195 27 276 for further details.
The invention will now be illustrated further by means of the following example.
AMENDED SHEET
Example 400 Nm3/h of off-gas from a process for drying powdered fluorinated polymer, at a temperature of 171~C, are introduced into a commercially available scrubbing column of length 2000 mm and internal diameter 250 mm. The off-gas contains 750 mg/Nm3 of perfluorooctanoic acid, corresponding to 300 g/h. Circa 20 kg/h of water are additionally conveyed with the off-gas from the dryer into the scrubbing process. The pressure in the scrubbing column is circa 1 bar absolute.
10 m3/h of an alkaline washing liquor, consisting essen-tially of aqueous potassium carbonate solution of density 1.30 g/cm3, at a temperature of 45~C, are introduced into the scrubber via a nozzle. The purified off-gas stream of 400 Nm3/h, now containing only 0.8 mg/Nm3 of perfluorooctanoic acid, corresponding to 0.32 g/h, escapes from the lower section of the scrubbing column.
Water vapor, corresponding to the water partial pressure, is additionally present at the temperature of circa 45~C
prevailing in the scrubber.
The scrubber is operated in co-current. The alkaline washing medium and the potassium salt of perfluoro-octanoic acid which is formed flow out of the column directly into a separating vessel of volume 0.4 m3, where the potassium salt of perfluorooctanoic acid, which is insoluble in the alkaline washing solution, floats to the top as a pulpy layer. The alkaline washing solution, which now contains practically no potassium salt of perfluorooctanoic acid, is withdrawn from the bottom of the separating vessel and pumped back into the scrubbing column. The concentration of dissolved potassium salt of perfluorooctanoic acid in the washing medium is about 170 mg/l. The density of the washing liquor is maintained at the desired value of about 1.30 g/cm3 by the addition of potassium carbonate. The potassium salt of perfluorooctanoic acid which has separated out as a pulpy ., , t - 4 -layer runs off into a tank through an overflow on the separating vessel, together with some washing medium.
The discharge process is aided by a very slow stirrer immersed directly in the upper layer. In the separating vessel, the separation of the washing solution and the potassium perfluorooctanoate foam formed is very good.
After standing for several hours, a further two phases separate out in the tank: a lower phase consisting essentially of excess washing liquor, and a pulpy upper phase. The lower phase is separated off and recycled into the washing process.
The pulpy upper phase contains 36% by weight of potassium perfluorooctanoate.
The concentrate obtained in this way is subjected to further working-up to give pure 100% by weight perfluorooctanoic acid.
It may be mentioned that although the concentrate obtained in this way is a stirrable and pumpable mixture, it does not constitute a stable solution of the potassium salt of perfluorooctanoic acid. To obtain a stable solution, it would be necessary to add even more water.
However, this is not absolutely necessary for further working-up.
Because the lower phase which has been separated off is recycled into the washing process as described, no perfluorooctanoic acid is lost. There is no observable impairment of the washing process due to encrustation in the column after several weeks of operation.
Claims
Claim A process for the recovery of highly fluorinated carboxylic acids from off-gas streams, in which the off-gas is brought into contact with an alkaline washing solution of density >1.15 g/cm3 so that the salt of the highly fluorinated carboxylic acid settles out as a separate phase, wherein the alkaline washing solution used is a potassium carbonate solution.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19631406.2 | 1996-08-05 | ||
| DE1996131406 DE19631406A1 (en) | 1995-07-26 | 1996-08-05 | Highly fluorinated carboxylic acid recovery from waste gas without scale formation in scrubber |
| PCT/EP1997/004146 WO1998005621A1 (en) | 1996-08-05 | 1997-07-30 | Recovery of highly fluorinated carboxylic acids from the gaseous phase |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2262702A1 true CA2262702A1 (en) | 1998-02-12 |
Family
ID=7801711
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002262702A Abandoned CA2262702A1 (en) | 1996-08-05 | 1997-07-30 | Recovery of highly fluorinated carboxylic acids from the gaseous phase |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US6245923B1 (en) |
| EP (1) | EP0938464B1 (en) |
| JP (1) | JP3937027B2 (en) |
| CN (1) | CN1074407C (en) |
| CA (1) | CA2262702A1 (en) |
| HK (1) | HK1020723A1 (en) |
| RU (1) | RU2187495C2 (en) |
| WO (1) | WO1998005621A1 (en) |
| ZA (1) | ZA976919B (en) |
Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7279522B2 (en) * | 2001-09-05 | 2007-10-09 | 3M Innovative Properties Company | Fluoropolymer dispersions containing no or little low molecular weight fluorinated surfactant |
| ITMI20021581A1 (en) * | 2002-07-18 | 2004-01-19 | Ausimont Spa | PROCEDURE FOR THE ABATEMENT OF FLUORINATED ANIONIC SURFACTANTS |
| JP2004065970A (en) * | 2002-07-22 | 2004-03-04 | Toshio Hayashi | Auxiliary implement for preparing food |
| EP1570917B1 (en) * | 2004-03-01 | 2009-06-10 | 3M Innovative Properties Company | Method of coating a substrate with a fluoropolymer dispersion |
| US7138551B2 (en) * | 2004-11-05 | 2006-11-21 | E. I. Du Pont De Nemours And Company | Purification of fluorinated alcohols |
| GB2427170A (en) * | 2005-06-17 | 2006-12-20 | 3M Innovative Properties Co | Fluoropolymer film having glass microspheres |
| GB0514398D0 (en) * | 2005-07-15 | 2005-08-17 | 3M Innovative Properties Co | Aqueous emulsion polymerization of fluorinated monomers using a fluorinated surfactant |
| GB0525978D0 (en) * | 2005-12-21 | 2006-02-01 | 3M Innovative Properties Co | Fluorinated Surfactants For Making Fluoropolymers |
| US7795332B2 (en) * | 2005-07-15 | 2010-09-14 | 3M Innovative Properties Company | Method of removing fluorinated carboxylic acid from aqueous liquid |
| US20080015304A1 (en) * | 2006-07-13 | 2008-01-17 | Klaus Hintzer | Aqueous emulsion polymerization process for producing fluoropolymers |
| GB0514387D0 (en) * | 2005-07-15 | 2005-08-17 | 3M Innovative Properties Co | Aqueous emulsion polymerization of fluorinated monomers using a perfluoropolyether surfactant |
| GB0523853D0 (en) | 2005-11-24 | 2006-01-04 | 3M Innovative Properties Co | Fluorinated surfactants for use in making a fluoropolymer |
| GB2430437A (en) * | 2005-09-27 | 2007-03-28 | 3M Innovative Properties Co | Method of making a fluoropolymer |
| US7728087B2 (en) | 2005-12-23 | 2010-06-01 | 3M Innovative Properties Company | Fluoropolymer dispersion and method for making the same |
| US7754795B2 (en) * | 2006-05-25 | 2010-07-13 | 3M Innovative Properties Company | Coating composition |
| US20070276103A1 (en) * | 2006-05-25 | 2007-11-29 | 3M Innovative Properties Company | Fluorinated Surfactants |
| US8119750B2 (en) * | 2006-07-13 | 2012-02-21 | 3M Innovative Properties Company | Explosion taming surfactants for the production of perfluoropolymers |
| BRPI0807109A2 (en) * | 2007-02-16 | 2014-05-06 | 3M Innovative Properties Co | Water Fluorochemical Removal System and Process |
| US20080264864A1 (en) | 2007-04-27 | 2008-10-30 | 3M Innovative Properties Company | PROCESS FOR REMOVING FLUORINATED EMULSIFIER FROM FLUOROPOLMER DISPERSIONS USING AN ANION-EXCHANGE RESIN AND A pH-DEPENDENT SURFACTANT AND FLUOROPOLYMER DISPERSIONS CONTAINING A pH-DEPENDENT SURFACTANT |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2432473A1 (en) * | 1974-07-06 | 1976-01-22 | Hoechst Ag | PROCESS FOR THE PRODUCTION OF LOW FATTY ACIDS AND HALOGEN FATTY ACIDS |
| US4060535A (en) * | 1976-08-31 | 1977-11-29 | Tenneco Chemicals, Inc. | Process for the production of metal salts of organic acids |
| EP0731081B1 (en) * | 1995-03-09 | 1998-04-15 | Dyneon GmbH | Recovery of highly fluorinated carboxylic acids from gaseous phase |
-
1997
- 1997-07-30 JP JP50757898A patent/JP3937027B2/en not_active Expired - Fee Related
- 1997-07-30 CN CN97195934A patent/CN1074407C/en not_active Expired - Fee Related
- 1997-07-30 RU RU99104514/04A patent/RU2187495C2/en not_active IP Right Cessation
- 1997-07-30 WO PCT/EP1997/004146 patent/WO1998005621A1/en active IP Right Grant
- 1997-07-30 US US09/214,456 patent/US6245923B1/en not_active Expired - Lifetime
- 1997-07-30 EP EP97940048A patent/EP0938464B1/en not_active Expired - Lifetime
- 1997-07-30 CA CA002262702A patent/CA2262702A1/en not_active Abandoned
- 1997-08-04 ZA ZA976919A patent/ZA976919B/en unknown
-
1999
- 1999-12-21 HK HK99105999A patent/HK1020723A1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| JP3937027B2 (en) | 2007-06-27 |
| EP0938464B1 (en) | 2002-07-31 |
| RU2187495C2 (en) | 2002-08-20 |
| CN1223632A (en) | 1999-07-21 |
| ZA976919B (en) | 1999-03-23 |
| HK1020723A1 (en) | 2000-05-19 |
| CN1074407C (en) | 2001-11-07 |
| EP0938464A1 (en) | 1999-09-01 |
| US6245923B1 (en) | 2001-06-12 |
| JP2001506966A (en) | 2001-05-29 |
| WO1998005621A1 (en) | 1998-02-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |