US3873630A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for pyrolyzing tetrafluoroethylene to hexafluoropropylene
Assignee: EIDP Inc
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Filing: 1972-06-12
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Granted: 1975-03-25
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Expires: 1992-06-12
Abstract
Abstract A feed mixture of tetrafluoroethylene and a minor proportion of carbon dioxide is fed to a pyrolysis furnace operating at about atmospheric pressure and a temperature of 700* to 900*C., and a conversion of 20 to 80 percent by weight, to a yield of at least 80 percent by weight of hexafluoropropylene and a mixture of carbon dioxide and unreacted tetrafluoroethylene which is distilled from the hexafluoropropylene. The distillate mixture can be recycled to the pyrolysis furnace.
Inventors
- 👤 Norman Eugene West
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:12
CPC Classifications
C; C07; C07C; C07C17/00; C07C17/26
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
116 words
IN A PROCESS FOR PYROLYZING IN A REACTION ZONE A FEED MIXTURE OF TETRAFLUOROTHYLENE (TFE) AT A TEMPERATURE BETWEEN 700* AND 900*C. TO CONVERT AT LEAST 20 PERCENT OF THE TFE TO HEXAFLUOROPROPYLENNE (HFP), WITH INNJECTION OF A MATERIAL SELECTED FROM THE CLASS OF HC1 OR HF INTO THE PYROLYSIS MIXTURE TO PREVENT POLYMERIZATION OF UNCONVERTED TFE, FOLLOWED BY COOLING AND SEPARATION OF HFP, AND RECYCLING OF UNCONVERTED TFE WITH MAKEUP TFE, THE IMPROVEMENT WHICH COMPRISES DILUTING THE FEED TO THE PYROLYSIS WITH CO2 AT A TFE:CO2 WEIGHT RATIO OF 1:1 TO 25:1 SO THE TFE PARTIAL PRES-S SURE IS AT LEAST 360 MM HG ABSOLUTE AND THE TOTAL PRESSURE IS 0.75 TO 2.0 ATMOSPHERES ABSOLUTE.
Claim 2
Dependent Claim
116 words
IN A PROCESS FOR PYROLYZING IN A REACTION ZONE A FEED MIXTURE OF TETRAFLUOROTHYLENE (TFE) AT A TEMPERATURE BETWEEN 700* AND 900*C. TO CONVERT AT LEAST 20 PERCENT OF THE TFE TO HEXAFLUOROPROPYLENNE (HFP), WITH INNJECTION OF A MATERIAL SELECTED FROM THE CLASS OF HC1 OR HF INTO THE PYROLYSIS MIXTURE TO PREVENT POLYMERIZATION OF UNCONVERTED TFE, FOLLOWED BY COOLING AND SEPARATION OF HFP, AND RECYCLING OF UNCONVERTED TFE WITH MAKEUP TFE, THE IMPROVEMENT WHICH COMPRISES DILUTING THE FEED TO THE PYROLYSIS WITH CO2 AT A TFE:CO2 WEIGHT RATIO OF 1:1 TO 25:1 SO THE TFE PARTIAL PRES-S SURE IS AT LEAST 360 MM HG ABSOLUTE AND THE TOTAL PRESSURE IS 0.75 TO 2.0 ATMOSPHERES ABSOLUTE.
Claim 3
Dependent Claim
36 words
The process of claim 1 wherein HCl or HF is separated from the cooled product mixture by water scrubbing, the HFP is separated from the TFE-CO2 mixture by distillation, and the TFE-CO2 mixture remaining is recycled.
Claim 4
Dependent Claim
57 words
The process of claim 1 wherein HCl or HF and CO2 is separated from the cooled product mixture by aqueous caustic scrubbing, the HFP is separated from the TFE by distillation, and the TFE remaining is recycled. 4. The process of claim 1 wherein at least 40 percent by weight of said feed mixture is carbon dioxide.
Claim 5
Dependent Claim
22 words
The process of claim 1 wherein the pyrolysis is conducted to a conversion of tetrafluoroethylene of 20 to 80 percent by weight.
Claim 6
Dependent Claim
22 words
The process of claim 5 wherein the pyrolysis is conducted to a yield of hexafluoropropylene of at least 80 percent by weight.
References Cited (Backward Citations)
US2394581A
Cited
US2551573A
Cited
US2758138A
Cited
US2759983A
Cited
US2970176A
Cited
US3009966A
Cited
US3519384A
Cited
US3578721A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |