Method for separating and recovering 2,3,3,3-tetrafluoropropene and hydrofluoric acid

Patent metadata

Field	Value
Publication number	US-9266799-B2
Application number	US-201214131036-A
Country	US
Kind code	B2
Filing date	Jun 14, 2012
Priority date	Jul 8, 2011
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

Abstract

The present invention relates to a method for separating a composition containing 2,3,3,3-tetrafluoropropene and hydrofluoric acid, and for recovering the thus-separated 2,3,3,3-tetrafluoropropene and hydrofluoric acid. The invention also relates to a method for manufacturing and purifying 2,3,3,3-tetrafluoropropene using a hydrofluorination reaction of the saturated or unsaturated compound having three carbon atoms and including at least one chlorine atom in the presence of a fluorination catalyst.

First claim

The invention claimed is:

1. A process for separating and recovering 2,3,3,3-tetrafluoropropene and HF from a composition comprising 2,3,3,3-tetrafluoropropene and HF, said process comprising cooling said composition at a temperature of between −5 and 35° C. in the presence of an added amount of at least one compound (C 1 ), whereby said separating occurs by settling and wherein C 1 is selected from the group consisting of chlorocarbons, hydrochlorocarbons, hydrochlorofluorocarbons, optionally fluorinated alcohols, optionally fluorinated ethers, ketones, esters, polyols and hydrofluorinated ethers, in order to give an upper phase rich in HF and a lower organic phase rich in 2,3,3,3-tetrafluoropropene and compound C 1 .

2. The process as claimed in claim 1 , characterized in that the 2,3,3,3-tetrafluoropropene/HF molar ratio in the composition is between 0.5 and 2.5.

3. The process as claimed in claim 1 , characterized in that the amount of compound C 1 to be added represents from 5% to 95% by weight, with respect to the 2,3,3,3-tetrafluoropropene/HF composition.

4. The process as claimed in claim 1 , further comprising hydrofluorinating at least one saturated or unsaturated hydrocarbon compound having three carbon atoms and at least one chlorine atom in the presence of a fluorination catalyst to produce the composition comprising 2,3,3,3-tetrafluoropropene and HF.

5. The process as claimed in claim 4 , characterized in that the saturated or unsaturated hydrocarbon compound having three carbon atoms is selected from the group consisting of 1,1,1,2,3-pentachloropropane, 1,1,2,3-tetrachloropropene and 2-chloro-3,3,3-trifluoropropene.

6. The process as claimed in claim 4 , further comprising removing HCl from the composition resulting from the hydrofluorination reaction before the cooling stage.

7. The process as claimed in claim 1 , characterized in that the compound C 1 is selected from the group consisting of 1,1,1,2,3-pentachloropropane, 1,1,2,3-tetrachloro-1-fluoropropane, 1,2-dichloro-3,3,3-trifluoropropane, 1,1,2,3-tetrachloropropene and 2-chloro-3,3,3-trifluoropropene.

8. The process as claimed in claim 1 , characterized in that the compound C 1 is selected from the group consisting of alcohols ROH, ketones RCOR′, esters RCOOR′, with R and R′, which are identical or different, each representing an alkyl group of 1 to 5 carbon atoms, and ethers ROR′, with R and R′, which are identical or different, each representing an alkyl group of 1 to 7 carbon atoms.

9. The process as claimed in claim 4 , characterized in that the compound C 1 is the same compound as that which was reacted with HF in the hydrofluorination reaction.

10. The process as claimed in claim 4 , further comprising recycling the phase enriched in HF after the cooling stage to the hydrofluorination reaction.

11. The process as claimed in claim 1 , further comprising separating 2,3,3,3-tetrafluoropropene from the organic phase enriched in 2,3,3,3-tetrafluoropropene after the cooling stage.

12. The process as claimed in claim 11 , further comprising recycling the organic phase, after separation of 2,3,3,3-tetrafluoropropene to the cooling stage and/or to the hydrofluorination reaction stage.

13. A process for the manufacture of 2,3,3,3-tetrafluoropropene, comprising (i) at least one reaction stage comprising reacting 1,1,1,2,3-pentachloropropane in the gas phase with HF in the presence of a fluorination catalyst to give a stream comprising 2,3,3,3-tetrafluoropropene and its intermediates, HCl and excess HF; (ii) removing HCl from the stream exiting from the reaction stage (i) to give a stream comprising 2,3,3,3-tetrafluoropropene and HF; (iii) cooling the stream exiting from stage (ii) to a temperature of between −5 and 35° C. in the presence of additional 1,1,1,2,3-pentachloropropane whereby the stream comprising 2,3,3,3-tetrafluoropropene and HF is separated by settling to produce an upper phase rich in HF and a lower organic phase rich in 2,3,3,3-tetrafluoropropene and comprising 1,1,1,2,3-pentachloropropane; (iv) separating the 2,3,3,3-tetrafluoropropene from the lower organic phase and optionally recycling the 1,1,1,2,3-pentachloropropane to the cooling stage (iii) and/or to the reaction stage (i); (v) purifying the 2,3,3,3-tetrafluoropropene and (vi) optionally recycling the upper phase rich in HF to stage (i).

14. The process as claimed in claim 13 , further comprising distilling HF before removing HCl in stage (ii).

Assignees

• Deur-Bert Dominique
• Collier Bertrand
• Arkema France

Inventors

• Deur-Bert Dominique
• Collier Bertrand

Classifications

• C07C17/25

  by splitting-off hydrogen halides from halogenated hydrocarbons · CPC title

• C07C17/35

  by reactions not affecting the number of carbon or of halogen atoms in the reaction · CPC title

• C07C17/20

  of halogen atoms by other halogen atoms · CPC title

• C07C17/38

  Separation; Purification; Stabilisation; Use of additives · CPC title

• C07C17/42 Primary

  Use of additives, e.g. for stabilisation · CPC title