Process for drying hydro(chloro)fluoroolefins

Patent metadata

Field	Value
Publication number	US-10647643-B2
Application number	US-201615745489-A
Country	US
Kind code	B2
Filing date	Jul 14, 2016
Priority date	Jul 17, 2015
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

The present invention provides a method for purifying a fluid comprising a first drying stage which comprises contacting a first fluid stream comprising one or more hydro(chloro)fluoroolefins and water with a source of sulphuric acid to produce a first treated fluid stream comprising the hydro(chloro)fluoroolefin(s) and a first spent sulphuric acid stream, wherein the first treated fluid stream comprises a lower concentration of water than the first fluid stream.

First claim

The invention claimed is:

1. A method for purifying a fluid comprising a first drying stage which comprises contacting a first fluid stream comprising one or more hydro(chloro)fluoroolefins and water with a source of sulphuric acid at a concentration between 75 wt % and 95 wt % to produce a first treated fluid stream comprising the hydro(chloro)fluoroolefin(s) and a first spent sulphuric acid stream, wherein the first treated fluid stream comprises a lower concentration of water than the first fluid stream.

2. A method comprising an integrated process for producing one or more hydro(chloro)fluoroolefins comprising:
dehydrohalogenating one or more hydro(chloro)fluoroalkanes to form a crude product stream;
subjecting the crude product stream to a first acid removal step comprising contacting the crude product stream with water or a source of aqueous acid to produce a treated product stream and a spent aqueous acid stream;
subjecting the treated product stream to a second acid removal step comprising contacting the treated product stream with a source of aqueous alkali to produce a second treated product stream and a spent aqueous alkali stream;
subjecting the second treated product stream, in the form of a first fluid stream, to a first drying stage comprising contacting the first fluid stream with a source of sulphuric acid at a concentration between 75 wt % and 95 wt % to produce a first treated fluid stream comprising the hydro(chloro)fluoroolefin(s) and a first spent sulphuric acid stream.

3. The method according to claim 1 , wherein the first treated fluid stream comprises less than 1 wt % water.

4. The method according to claim 1 , wherein the first fluid stream comprises less than 20 wt % HF.

5. The method according to claim 1 , wherein the first fluid stream comprises less than 20 wt % HCl.

6. The method according claim 1 , wherein at least 50 wt % of the first fluid stream comprises the hydro(chloro)fluoroolefin(s).

7. The method according to claim 6 , wherein at least 50 wt % of the first fluid stream comprises a hydro(chloro)fluoroolefin selected from the group consisting of hydrofluoropropenes, hydrochlorofluoropropenes, hydrofluoroethylenes, hydrofluorobutenes and hydrochlorofluorobutenes.

8. The method according claim 1 , wherein the hydro(chloro)fluoroolefins include one or more of HFO-1234yf, HFO-1234ze, 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), 1,1,1-4,4,4-hexafluoro-but-2-ene (HFO-1336mzz) and 1,1-difluoroethylene (HFO-1132a).

9. The method according to claim 1 , wherein the first fluid stream is contacted with the source of sulphuric acid at a temperature between 10° C. and 70° C.

10. The method according to claim 1 , wherein the first spent sulphuric stream comprises less than 20000 ppm fluoride.

11. The method according to claim 1 , wherein the first spent sulphuric stream comprises less than 10000 ppm total organic carbon.

12. The method according to claim 1 , wherein the first spent sulphuric stream comprises one or more compounds selected from fluoracrylic acid, polyfluoracrylic acid, formic acid and fluoroformaldehyde, and/or one or more unsaturated fluorine containing oligomers.

13. The method according to claim 1 , wherein the method comprises a second drying step comprising contacting the first treated fluid stream with a second source of sulphuric acid to produce a second treated fluid stream comprising the hydro(chloro)fluoroolefin(s) and a second spent sulphuric acid stream, wherein the second treated fluid stream comprises a lower concentration of water than the fluid stream.

14. The method according to claim 13 , wherein the first source of sulphuric acid comprises aqueous sulphuric acid in a concentration between 78 wt % and 90 wt %.

15. The method according to claim 13 , wherein the second treated fluid stream comprises less than 500 ppm water.

16. The method according to claim 15 , wherein the second source of sulphuric acid comprises aqueous sulphuric acid at a concentration between 60 wt % and 98 wt %.

17. The method according to claim 13 , wherein the first treated fluid stream is contacted with the second source of sulphuric acid at a temperature between 10° C. and 70° C.

18. The method according to claim 13 , wherein the second spent sulphuric stream comprises less than 20000 ppm fluoride.

19. The method according to claim 13 , wherein the second spent sulphuric stream comprises less than 10000 ppm total organic carbon.

20. The method according to claim 13 wherein the second spent sulphuric stream comprises one or more compounds selected from fluoracrylic acid, polyfluoracrylic acid, formic acid and fluoroformaldehyde, and/or one or more unsaturated fluorine containing oligomers.

21. The method according claim 1 , wherein the first and/or, if produced, second treated fluid stream(s) comprise the hydro(chloro)fluoroolefins in a purity of at least 99 wt %.

22. The method according to claim 1 , wherein the first and/or, if produced, second treated fluid stream is contacted with an adsorbent material.

23. The method according to claim 22 , wherein the adsorbent material comprises soda lime and/or one or more molecular sieves, for example one or more zeolites having pores sizes in the region of 2 Å to 10 Å.

24. The method according to claim 1 , wherein the first treated fluid stream, is subjected to distillation to separate some or all of the remaining components.

25. The method according to claim 1 further comprising a preceding acid removal step which preferably comprises the treatment of a crude product stream to remove at least a portion of any HF and/or HCl in the crude product stream to provide the first fluid stream.

26. The method according to claim 1 , wherein the crude product stream is the product stream of a dehydrohalogenation reaction.

27. The method according to claim 1 , wherein the acid removal step comprises contacting the crude product stream with water to produce a spent stream of aqueous acid and a treated product stream, the treated product stream having a lower acid concentration than the crude product stream.

28. The method according to claim 1 , wherein the acid removal step comprises contacting the crude product stream with a source of aqueous acid to produce a spent stream of aqueous acid and a treated product stream, the treated product stream having a lower acid concentration than the crude product stream.

29. The method according to claim 28 , wherein the source of aqueous acid comprises aqueous HF a concentration between 30 wt % and 60 wt %.

30. The method according to claim 2 , wherein the treated product stream is provided directly to the first drying stage, in the form of the first fluid stream.

31. The method according to claim 2 , wherein the treated product stream is subjected to one or more further treatment steps before being provided to the first drying stage.

32. The method according to claim 29 , wherein the treated product stream is subjected to a second acid removal step.

33. The method according to claim 32 , wherein the source of aqueous alkali comprises an aqueous caustic solution.

34. The method according to claim 32 , wherein the second treated product stream is provided directly to the first drying stage.

Assignees

• Mexichem Fluor Sa De Cv

Inventors

• Hodgson Emma Jayne
• Murray James Henry
• Lloyd Gary

Classifications

• C07C17/38 Primary

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

• C07C21/18

  containing fluorine · CPC title

• Y02P20/10

  Process efficiency · CPC title

• C07C17/389

  by adsorption on solids · CPC title