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, 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 reduces the concentration of the undesired (hydro)halocarbon by at least about 50% by weight.

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

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

4. The process according to claim 1, wherein the basic 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 or arylalkyl group.

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

6. The process according to claim 1, wherein the basic solution has a concentration of from about 0.1 to about 10 M.

7. The process according to claim 6, wherein the basic solution has a concentration of from about 0.2 to about 5 M.

8. The process according to claim 6, wherein the basic solution has a concentration of from about 0.5 to about 3 M.

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

10. The process according to claim 9, wherein the C.sub.3-7(hydro)haloalkene is a hydrohalopropene.

11. The process according to claim 10, wherein the hydrohalopropene is a chlorotrifluoropropene and/or a tetrafluoropropene.

12. The process according to claim 11, wherein the chlorotrifluoropropene is CF.sub.3CHCHCl (HCFO-1233zd) and/or CF.sub.3CClCH.sub.2 (HCFO-1233xf).

13. The process according to claim 11, wherein the tetrafluoropropene is CF.sub.3CHCHF (HFO-1234ze) and/or CF.sub.3CFCH.sub.2 (HFO-1234yf).

14. The process according to claim 1, wherein the process is carried out in the presence of a phase transfer catalyst.

15. The process according to claim 1, wherein the process is carried out at a temperature of from about 0 to about 100 C.

16. The process according to claim 15, wherein the process is carried out at a temperature of from about 10 to about 80 C.

17. The process according to claim 15, wherein the process is carried out at a temperature of from about 20 to about 60 C.

18. The process according to claim 1 having a contact time between the composition and the basic solution of from about 1 second to about 4 hours.

19. The process according to claim 18, wherein the contact time is from about 10 seconds to about 3 hours.

20. The process according to claim 18, wherein the contact time is from about 1 minute to about 180 minutes.

21. The process according to claim 1 wherein the composition is in the gas phase at least prior to contacting the basic solution.

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

23. The process according to claim 22, wherein the composition, prior to the contacting step, comprises at least about 95% by weight of the (hydro)halocarbon.

24. The process according to claim 1 wherein the composition, prior to the contacting step, contains about 10000 ppm or less of the compound of formula R.sub.fCCX.

25. The process according to claim 24, wherein the composition, prior to the contacting step, contains about 5000 ppm or less of the compound of formula Rf-CCX.

26. The process according to claim 24, wherein the composition, prior to the contacting step, contains about 1000 ppm or less of the compound of formula Rf-CCX.

27. The 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.

28. The process according to claim 27, wherein the amount of the compound of formula Rf-CCX in the composition is reduced by at least about 70% by weight.

29. The process according to claim 27, wherein the amount of the compound of formula Rf-CCX in the composition is reduced by at least about 90% by weight.

30. The process according to claim 1 wherein following the contacting step, the resulting composition contains from 0 to about 500 ppm of the compound of formula R.sub.fCCX.

31. The process according to claim 30, wherein following the contacting step the resulting composition contains from 0 to about 100 ppm of the compound of formula Rf-CCX.

32. The process according to claim 30, wherein following the contacting step the resulting composition contains from 0 to about 10 ppm of the compound of formula Rf-CCX.

33. The process according to claim 1 wherein the undesired (hydro)halocarbon is selected from the group consisting of pentafluoropropenes, pentafluoropropanes, chlorotetrafluoropropanes, hexafluoropropanes and mixtures thereof.

34. The process according to claim 1 wherein the undesired (hydro)halocarbon is one or more of CF.sub.3CFHCFH (HFO-1225ye), CF.sub.3CFHCFH.sub.2 (HFC-245eb), CF.sub.3CHF.sub.2CF.sub.2H (HFC-245fa), CF.sub.3CF.sub.2CH.sub.3 (HFC-245cb), CF.sub.3CFClCH.sub.3 (HCFC-244bb) and CF.sub.3CFHCF.sub.2H (HFC-236ea).

35. The process according to claim 1 wherein the amount of the undesired (hydro)halocarbon in the composition is reduced by at least about 50% by weight.

36. The process according to claim 35, wherein the amount of the undesired (hydro)halocarbon in the composition is reduced by at least about 90% by weight.

37. The process according to claim 1 wherein following the contacting step, the resulting composition contains from 0 to about 500 ppm of the compound of the undesired (hydro)halocarbon.

38. The process according to claim 37, wherein following the contacting step, the resulting composition contains from 0 to about 100 ppm of the compound of the undesired (hydro)halocarbon.

39. The process according to claim 37, wherein following the contacting step, the resulting composition contains from 0 to about 10 ppm of the compound of the undesired (hydro)halocarbon.

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

41. The process according to claim 40 combined with one or more additional purification steps.

Description

EXAMPLES

Experimental

(1) 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.

(2) 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.

(3) Results

(4) 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.

(5) 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

(6) 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

(7) 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

(8) 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

(9) 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

(10) 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

(11) 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

(12) 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

(13) 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.

(14) 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.

(15) 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

(16) 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

(17) 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

(18) 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.

(19) 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.

(20) Results

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

(22) 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

(23) 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

(24) 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

(25) 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

(26) 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

(27) 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.

(28) The invention is defined by the claims.