PROCESS FOR THE REMOVAL OF HALOALKYNE IMPURITIES FROM (HYDRO)HALOCARBON COMPOSITIONS

Abstract

The invention relates to a process comprising contacting a composition comprising a (hydro)halocarbon and a compound of formula R.sub.fCCX with a basic solution comprising an hydroxide, an alkoxide and/or an amide to reduce the concentration of R.sub.fCCX, wherein R.sub.f is a perfluorinated alkyl group and X is H, F, Cl, Br, or I. The invention further relates to process for preparing a (hydro)halocarbon comprising (i) converting a starting material, optionally in the presence of HF and/or a catalyst, to a composition comprising the (hydro)halocarbon and a compound of formula R.sub.fCCX, wherein R.sub.f is a perfluorinated alkyl group and X is H, F, Cl, Br, or I; (ii) contacting the composition with a basic solution comprising an hydroxide, an alkoxide and/or an amide to reduce the concentration of the compound of formula R.sub.fCCX; and (iii) recovering the (hydro)halocarbon.

Claims

1. A process comprising contacting a composition comprising a (hydro)halocarbon and a compound of formula R.sub.fCCX with a basic solution comprising an hydroxide, alkoxide and/or an amide to reduce the concentration of R.sub.fCCX, wherein R.sub.f is a perfluorinated alkyl group and X is H, F, Cl, Br, or I.

2. A process according to claim 1, wherein the compound of formula R.sub.fCCX is 3,3,3-trifluoropropyne (trifluoromethylacetylene, TFMA).

3. A process according to claim 1, wherein the solution is an aqueous solution.

4. A process according to claim 1, wherein the solution comprises one or more of an alkali metal hydroxide, alkoxide or amide, an alkaline earth metal hydroxide or amide, or NR.sub.4OH, wherein R is, independently, H, C.sub.1-10 alkyl, aryl (e.g. phenyl, naphthyl or pyridinyl) or arylalkyl group (e.g. benzyl or C.sub.1-10 alkyl-substituted phenyl).

5. A process according claim 1, wherein the solution contains one or more of potassium hydroxide (KOH), sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH).sub.2).

6. A process according to claim 1, wherein the solution has a concentration of from about 0.1 to about 10 M, preferably from about 0.2 to about 5 M, such as from about 0.5 to about 3 M.

7. A process according to claim 1, wherein the (hydro)halocarbon is a C.sub.3-7 (hydro)haloalkene, preferably a hydrohalopropene.

8. A process according to claim 7, wherein the hydrohalopropene is a chlorotrifluoropropene and/or a tetrafluoropropene.

9. A process according to claim 8, wherein the chlorotrifluoropropene is CF.sub.3CHCHCl (HCFO-1233zd) and/or CF.sub.3CClCH.sub.2 (HCFO-1233xf).

10. A process according to claim 8, wherein the tetrafluoropropene is CF.sub.3CHCHF (HFO-1234ze) and/or CF.sub.3CFCH.sub.2 (HFO-1234yf).

11. A process according to claim 1 carried out in the presence of a phase transfer catalyst.

12. A process according to claim 1 carried out at a temperature of from about 0 to about 100 C., preferably from about 10 to about 80 C., such as from about 20 to about 60 C.

13. A process according to claim 1 having a contact time between the composition and the solution of from about 1 second to about 4 hours, preferably from about 10 seconds to about 3 hours, such as from about 1 minute to about 180 minutes.

14. A process according to claim 1 wherein the composition is in the gas phase as least prior to contacting the solution.

15. A process according to claim 1 wherein the composition, prior to the contacting step, comprises at least about 90% by weight of the (hydro)halocarbon, preferably at least about 95% by weight.

16. A process according to claim 1 wherein the composition, prior to the contacting step, contains about 10000 ppm or less, preferably about 5000 ppm or less, such as about 1000 ppm or less, of the compound of formula R.sub.fCCX.

17. A process according to claim 1 wherein the amount of the compound of formula R.sub.fCCX in the composition is reduced by at least about 50% by weight, preferably at least about 70% by weight, such as at least about 90% by weight.

18. A process according to claim 1 wherein following the contacting step, the resulting composition contains from 0 to about 500 ppm, preferably from 0 to about 100 ppm, such from 0 to about 10 ppm, of the compound of formula R.sub.fCCX.

19. A process according to claim 1 wherein the composition comprising a (hydro)halocarbon and a compound of formula R.sub.fCCX further comprises an undesired (hydro)halocarbon, and wherein contacting the composition with the basic solution comprising an hydroxide, an alkoxide and/or an amide reduces the concentration of the undesired (hydro)halocarbon.

20. A process according to claim 19 wherein the undesired (hydro)halocarbon is selected from pentafluoropropenes, pentafluoropropanes, chlorotetrafluoropropanes, hexafluoropropanes and mixtures thereof.

21. A process according to claim 20 wherein the undesired (hydro)halocarbon is one or more of CF.sub.3CFHCFH (HFO-1225ye), HFC-245eb, HFC-245fa, HFC-245cb, HCFC-244bb and HFC-236ea.

22. A process according to claim 19 wherein the amount of the undesired (hydro)halocarbon in the composition is reduced by at least about 50% by weight, preferably at least about 70% by weight, such as at least about 90% by weight.

23. A process according to claim 19 wherein following the contacting step, the resulting composition contains from 0 to about 500 ppm, preferably from 0 to about 100 ppm, such from 0 to about 10 ppm, of the compound of the undesired (hydro)halocarbon.

24. A process according to claim 1 wherein the composition is a product stream from a process for producing the (hydro)halocarbon.

25. A process according to claim 24 combined with one or more additional purification steps.

26. A process for preparing a (hydro)halocarbon comprising: (i) converting a starting material, optionally in the presence of HF and/or a catalyst, to a composition comprising the (hydro)halocarbon and a compound of formula R.sub.fCCX, wherein R.sub.f is a perfluorinated alkyl group and X is H, F, Cl, Br, or I; (ii) contacting the composition with a basic solution comprising an hydroxide, alkoxide and/or an amide to reduce the concentration of the compound of formula R.sub.fCCX; and (iii) recovering the (hydro)halocarbon.

27. A process according to claim 26, wherein the compound of formula R.sub.fCCX is 3,3,3-trifluoropropyne (trifluoromethylacetylene, TFMA).

28. A process according to claim 26, wherein solution is an aqueous solution.

29. A process according to claim 26, wherein the solution comprises one or more of an alkali metal hydroxide, alkoxide or amide, an alkaline earth metal hydroxide or amide, or NR.sub.4OH, wherein R is, independently, H, C.sub.1-10 to alkyl, aryl (e.g. phenyl, naphthyl or pyridinyl) or arylalkyl group (e.g. benzyl or C.sub.1-10 alkyl-substituted phenyl).

30. A process according to claim 29, wherein the solution contains one or more of potassium hydroxide (KOH), sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH).sub.2).

31. A process according to claim 26, wherein the solution has a concentration of from about 0.1 to about 10 M, preferably from about 0.2 to about 5 M, such as from about 0.5 to about 3 M.

32. A process according to claim 26, wherein the (hydro)halocarbon is a C.sub.3-7 (hydro)haloalkene, preferably a hydrohalopropene.

33. A process according to claim 32, wherein the hydrohalopropene is a chlorotrifluoropropene and/or a tetrafluoropropene.

34. A process according to claim 33 wherein the starting material comprises one or more of CCl.sub.3CH.sub.2CCl.sub.2H (HFC-240fa), CF.sub.3CH.sub.2CFClH (HCFC-244fa), CF.sub.3CH.sub.2CF.sub.2H (HFC-245fa), CF.sub.3CF.sub.2CH.sub.3 (HFC-245cb), CF.sub.3CFHCFH.sub.2 (HFC-245eb), CF.sub.3CFClCH.sub.3 (ICFC-244bb), CF.sub.3CHClCH.sub.2Cl (HCFC-243db), HCFO-1233xf, a tetrachloropropene (IHCO-1230), Z-HIFO-1234ze, Z-HICFO-1233zd, HFO-1234zc or CCl.sub.3CClHCClH.sub.2 (HFC-240db).

35. A process according to claim 33, wherein the hydrohalopropene is HCFO-1233zd and/or HFO-1234ze, and wherein the starting material comprises one or more of CCl.sub.3CH.sub.2CCl.sub.2H (HFC-240fa), CF.sub.3CH.sub.2CFClH (HCFC-244fa) or CF.sub.3CH.sub.2CF.sub.2H (HFC-245fa).

36. A process according to claim 33, wherein the hydrohalopropene is HFO-1234yf and the starting material comprises one or more of CF.sub.3CF.sub.2CH.sub.3 (HFC-245cb), CF.sub.3CFHCFH.sub.2 (HFC-245eb), CF.sub.3CFClCH.sub.3 (HCFC-244bb), CF.sub.3CHClCH.sub.2Cl (HCFC-243db), HCFO-1233xf, a tetrachloropropene (HCO-1230) or CCl.sub.3CClHCClH.sub.2 (HFC-240db).

37. A process according to claim 33, wherein the hydrohalopropene is HCFO-1233xf and the starting material comprises a tetrachloropropene (HCO-1230) and/or CCl.sub.3CClHCClH.sub.2 (HFC-240db).

38. A process according to claim 33, wherein the (hydro)halocarbon is HCFC-244bb and the starting material comprises one or more of HCFO-1233xf, a tetrachloropropene (HCO-1230) or CCl.sub.3CClHCCl.sub.2 (HFC-240db).

39. A process according to claim 26 wherein the contacting step is carried out in the presence of a phase transfer catalyst.

40. A process according to claim 26 wherein the contacting step is carried out at a temperature of from about 0 to about 100 C., preferably from about 10 to about 80 C., such as from about 20 to about 60 C.

41. A process according to claim 26 wherein the contacting step has a contact time between the composition and the solution of from about 1 second to about 4 hours, preferably from about 10 seconds to about 3 hours, such as from about 1 minute to about 180 minutes.

42. A process according to claim 26 wherein the composition is in the gas phase as least prior to contacting the solution.

43. A process according to claim 26 wherein the composition, prior to the contacting step, comprises at least about 90% by weight of the (hydro)halocarbon, preferably at least about 95% by weight.

44. A process according to claim 26 wherein the composition, prior to the contacting step, contains about 10000 ppm or less, preferably about 5000 ppm or less, such as about 1000 ppm or less, of the compound of formula R.sub.fCCX.

45. A process according to claim 26 wherein the amount of the compound of formula R.sub.fCCX in the composition is reduced in the contacting step by at least about 50% by weight, preferably at least about 70% by weight, such as at least about 90% by weight.

46. A process according to claim 26 wherein following the contacting step, the resulting composition contains from 0 to about 500 ppm, preferably from 0 to about 100 ppm, such from 0 to about 10 ppm, of the compound of formula R.sub.fCCX.

47. A process according to claim 26 further comprising one or more additional purification steps.

48. A process according to claim 26 wherein HF is present in the composition resulting from the converting step.

49. A process according to claim 48 wherein at least some of the HF in the composition is removed prior to the contacting step.

Description

EXAMPLES

Experimental

[0089] A feed mixture was prepared by adding TFMA (2.5 g) to HFO-1234yf (499.98 g). This mixture, containing 0.50% wt TFMA, was used for all experiments.

[0090] The solid base was accurately weighed into a 100 ml Hastelloy C22 autoclave and dissolved in a known weight of deionised water. If used, the phase transfer catalyst was also added at this point. The vessel was sealed, purged with nitrogen and evacuated. It was then pressurised (4-4.5 Barg) with the HFO-1234yf/TFMA feed mixture. The contents of the vessel were then stirred at 1000 rpm and heated to the desired temperature over a period of 4 to 5 minutes. Once at the desired temperature, samples of the gas in the headspace of the vessel were periodically withdrawn and analysed by gas chromatography.

Results

[0091] The experiments were performed using a variety of basic reagents at different concentrations, temperatures and both in the presence and absence of a phase transfer catalyst (Aliquat 336). The results are set out in Tables 1 to 8.

TABLE-US-00001 TABLE 1 (Example 1) Base KOH (85 wt %) 2.1 g Concentration (mol/L) 0.64 Temperature ( C.) 50 Time (mins) TFMA (wt %) 1234yf (%) 0 0.50 99.46 33.66 0.37 99.60 71 0.27 99.71 129 0.19 99.81 177 0.13 99.87

TABLE-US-00002 TABLE 2 (Example 2) Base KOH (85 wt %) 4.1 g Concentration (mol/L) 1.24 Temperature ( C.) 50 Time (mins) TFMA (wt %) 1234yf (%) 0 0.50 99.43 27.5 0.27 99.68 52 0.20 99.78 90 0.13 99.86 193 0.04 99.95

TABLE-US-00003 TABLE 3 (Example 3) Base KOH (85 wt %) 2.1 g Concentration (mol/L) 0.64 Temperature ( C.) 70 Time (mins) TFMA (wt %) 1234yf (%) 0 0.50 99.48 25 0.20 99.80 63 0.05 99.95 104 0.02 99.98 130 0.01 99.99

TABLE-US-00004 TABLE 4 (Example 4) Base KOH (85 wt %) 4.2 g Concentration (mol/L) 1.27 Temperature ( C.) 70 Time (mins) TFMA (wt %) 1234yf (%) 0 0.50 99.49 16 0.19 99.81 50 0.05 99.95 83 0.02 99.98 118 0.01 99.99

TABLE-US-00005 TABLE 5 (Example 5) Base KOH (85 wt %) 4.0 g Concentration (mol/L) 1.21 Temperature ( C.) 50 Phase transfer catalyst Aliquat 336 0.1 g Time (mins) TFMA (wt %) 1234yf (%) 0 0.50 99.48 25 0.17 99.83 62 0.05 99.95 88 0.02 99.98 124 0.01 99.99

TABLE-US-00006 TABLE 6 (Example 6) Base NaOH (85 wt %) 2.1 g Concentration (mol/L) 1.03 Temperature ( C.) 50 Time (mins) TFMA (wt %) 1234yf (%) 0 0.50 99.46 22 0.43 99.54 74 0.27 99.71 103 0.19 99.80 178 0.10 99.89

TABLE-US-00007 TABLE 7 (Example 7) Base NaOH (85 wt %) 4.0 g Concentration (mol/L) 1.97 Temperature ( C.) 70 Phase transfer catalyst Aliquat 336 0.1 g Time (mins) TFMA (wt %) 1234yf (%) 0 0.50 99.47 13 0.23 99.75 27 0.07 99.93 71 0.01 99.99 130 0.00 100.00

TABLE-US-00008 TABLE 8 (Example 8) Base CaO 2.55 g Concentration (mol/L) 0.83 Temperature ( C.) 50 Time (mins) TFMA (wt %) 1234yf (%) 0 0.54 99.43 39 0.51 99.46 76 0.50 99.47 130 0.48 99.48 180 0.47 99.50

[0092] It can be seen that treatment with a base is very effective in reducing the absolute concentration of TFMA in the mixture and increasing the HFO-1234yf content of the mixture relative to TFMA overall.

[0093] A reduction in other trace impurities was also observed following treatment with a base. The results of reducing other impurities are summarised in Tables 9 and 10.

TABLE-US-00009 TABLE 9 (Example 9) Base NaOH (85 wt %) 4.0 g Concentration (mol/L) 1.97 Temperature ( C.) 70 Phase transfer catalyst Aliquat 336 0.1 g Area Counts in Area counts in 1234yf feed 1234yf after Reduction Species material treatment (%) Z-1225ye 14.81 3.00 79.8 236ea 2.02 0.00 100.0 245eb 21.75 0.00 100.0

TABLE-US-00010 TABLE 10 (Example 10) Base KOH (85 wt %) 4.1 g Concentration (mol/L) 1.24 Temperature ( C.) 50 Area Counts in Area counts in 1234yf feed 1234yf after Reduction Species material treatment (%) 236ea 2.55 0.27 89.4 245eb 23.97 0.00 100.0

[0094] The process of the invention is therefore also effective in reducing the levels of R-1225ye(Z), R-236ea and R-245eb in a composition comprising HFO-1234yf.

Experimental

[0095] A feed mixture was prepared by adding TFMA (1.25 g) to an HFO (250 g). These mixtures, containing 0.50% wt TFMA, were used for all experiments.

[0096] In a typical scrubbing experiment the base was accurately weighed into a 100 ml Hastelloy C22 autoclave and dissolved in a known weight of deionised water or solvent. If used, any further additives e.g. KF or catalysts were also added at this point. The vessel was then sealed, purged with nitrogen, evacuated and heated to the desired temperature over 5 minutes. Once at temperature the vessel was then pressurised with the HFO/TFMA feed mixture. The contents of the vessel were then stirred at 1000 pm and samples of the gas in the headspace of the vessel were periodically withdrawn and analysed by gas chromatography.

Results

[0097] The experiments were performed using a variety of basic reagents and hydrofluoroolefins (HFOs). The results are set out in Tables 11 to 15.

TABLE-US-00011 TABLE 11 (Example 11 - TFMA removal from E-1234ze) Base KOH (85 wt %) 4.1 g Concentration (mol/l) 1.24 Temperature ( C.) 50 Time (mins) TFMA (wt %) E-1234ze (%) 0 0.50 99.2 1 0.46 99.2 9.5 0.45 99.0 37 0.35 98.9 62 0.29 99.0 91 0.21 99.2

TABLE-US-00012 TABLE 12 (Example 12 - TFMA removal from 1233xf*) Base KOH (85 wt %) 4.1 g Concentration (mol/l) 1.24 Temperature ( C.) 50 Time (mins) TFMA (wt %) E-1233xf (%) 0 0.50 98.79 60 0.16 99.29

TABLE-US-00013 TABLE 13 (Example 13 - TFMA removal from 1234yf with Sodium Ethoxide in Ethanol) Base solution 20 g 21% NaOEt/Ethanol + 40 g Ethanol Temperature ( C.) 50 Time (mins) TFMA (%) E-1234yf (%) 0 0.50 98.96 10 0.10 99.73 30 0.03 99.89 56 0.01 99.95

TABLE-US-00014 TABLE 14 (Example 14 - TFMA removal from E- 1234yf in the presence of fluoride) Base KOH (85 wt %) 5.1 g + 0.06 g KF Base concentration (mol/l) 1.51 Temperature ( C.) 60 Time (mins) TFMA (wt %) E-1234yf (%) 0 0.50 98.96 60 0.17 99.63

TABLE-US-00015 TABLE 15 (Example 15 - TFMA removal from E- 1234yf in the absence of fluoride) Base KOH (85 wt %) 5.1 g Base concentration (mol/l) 1.51 Temperature ( C.) 60 Time (mins) TFMA (wt %) E-1234yf (%) 0 0.50 98.96 60 0.17 99.59

[0098] It can be seen that treatment with a base is very effective in reducing the absolute concentration of TFMA in its mixture with a range of HFOs, and increasing the HFO content of the mixture relative to TFMA overall.

[0099] The invention is defined by the claims.