Method for producing 2-chloro-3,3,3-trifluoropropene

Abstract

The invention relates to a method for producing 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) from at least one compound A selected from the group consisting of halopropane of formulae CX.sub.3CHClCH.sub.2X or CX.sub.3CFClCH.sub.3, or halopropenes of formula CQX.sub.2CCNCH.sub.2 and CX.sub.2CClCH.sub.2X where X independently represents a fluorine or chlorine atom, characterised in that it comprises bringing said at least one compound A into contact with HF in a gaseous phase in the presence of a fluorination catalyst AlF.sub.3 or fluorine-bearing alumina in order to form a gaseous flow B comprising 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) et 3,3,3-trifluoropropene (HFO-1243zf).

Claims

1. A process for manufacturing 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) starting with at least one compound A comprising a halopropane of formula CX.sub.3CHClCH.sub.2X or CX.sub.3CFClCH.sub.3, or halopropenes of formula CClX.sub.2CClCH.sub.2 or CX.sub.2CClCH.sub.2X with X independently representing a fluorine or chlorine atom, the process comprising placing said at least one compound A in contact with HF in the gaseous phase at a temperature of between 225 C. and 450 C. in the presence of a fluorination catalyst AlF.sub.3 or fluorinated alumina to form a gaseous stream B comprising 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) and 3,3,3-trifluoropropene (HFO-1243zf).

2. The process as claimed in claim 1, wherein stream B also comprises trichlorofluoropropene (HCFO-1231).

3. The process as claimed in claim 1, wherein stream B also comprises a dichlorodifluoropropene (HCFO-1232).

4. The process as claimed in claim 1, wherein the placing in contact is performed at a temperature of between 250 C. and 400 C.

5. The process as claimed in claim 1, wherein the placing in contact is performed with a mole ratio of HF relative to said at least one compound A of between 0.5and 50.

6. The process as claimed in claim 1, wherein the placing in contact is performed at a pressure of between 0.5 and 20 bar.

7. The process as claimed in claim 1, wherein the placing in contact is performed in the absence of stabilizer.

8. The process as claimed in claim 1, wherein said at least one compound A is selected from the group consisting of 2,3-dichloro-1,1,1-trifluoropropane (HCFC-243db), 1,1,1,2,3-pentachloropropane (HCC-240db), 2,3,3,3-tetrachloropropene (HCO-1230xf), 1,1,2,3-tetrachloropropene (HCO-1230xa), and mixtures thereof.

9. The process as claimed in claim 1, wherein stream B also comprises 2,3,3,3-tetrachloropropene (HCO-1230xf), 1,1,2,3-tetrachloropropene (HCO-1230xa), 1,1,1,2,3-pentachloropropane (HCC-240db), 1,1,2,3-tetrachloro-1-fluoropropane (HCFC-241db), 1,2,3-trichloro-1,1-difluoropropane (HCFC-242dc) or mixtures thereof.

10. The process as claimed in claim 9, further comprising separating stream B to form a liquid phase C and a gaseous stream D; the liquid phase C comprising 2,3,3,3-tetrachloropropene (HCO-1230xf), 1,1,2,3-tetrachloropropene (HCO-1230xa), 1,1,1,2,3-pentachloropropane (HCC-240db), 1,1,2,3-tetrachloro-1-fluoropropane (HCFC-241db) and 1,2,3-trichloro-1,1-difluoropropane (HCFC-242dc); and the gaseous stream D comprising 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), 3,3,3-trifluoropropene (HFO-1243zf), trichlorofluoropropene (HCFC-1231) and dichlorodifluoropropene (HCFC-1232).

Description

EXPERIMENTAL SECTION

(1) The fluorination reactor is charged with a bed of catalyst of AlF.sub.3 type. The reaction for the fluorination of HCC-240db is performed at a temperature of between 275 and 375 C. at an absolute pressure of 1 bar. A series of four tests was performed according to the conditions collated in table 1 below.

(2) TABLE-US-00001 TABLE 1 Experimental conditions Temp. HF/240db Contact time Contact duration Ex. ( C.) mole ratio (sec) (h) 1 275 5:1 5 0-95 2 350 5:1 5 95-170 3 350 5:1 10 170-242 4 375 5:1 10 242-312

(3) The stream obtained at the end of the reaction is condensed to form a liquid phase and a gaseous phase. The liquid phase obtained is analysed by .sup.1H and .sup.19F NMR. The results are collated in table 2.

(4) TABLE-US-00002 TABLE 2 NMR data (mol %) based on .sup.1H and .sup.19F NMR. Products identified Ex. 1 Ex. 2 Ex. 3 Ex. 4 HFO-1233xf 0.2 0.2 0.1 0.2 CF.sub.3CClCH.sub.2 HCFO-F1232xf 4.3 2.4 1.6 2.3 CF.sub.2ClCClCH.sub.2 HCFO-F1231xf 6.9 6.6 7.0 8.9 CFCl.sub.2CClCH.sub.2 HCFO-F1231xb 4.2 3.2 3.4 4.3 CH.sub.2ClCClCFCl HCFO-F1231xa 0.4 0.5 0.3 0.2 CH.sub.2FCClCCl.sub.2 HCO-F1230xf 4.3 22.3 22.9 23.0 CCl.sub.3CClCH.sub.2 HCO-F1230xa 53.3 42.7 39.2 42.2 CH.sub.2ClCClCCl.sub.2 HCC-F240db 19.1 19.5 22.9 16.6 CCl.sub.3CHClCH.sub.2Cl HCFC-F241db 6.9 2.4 2.4 2.1 CFCl.sub.2CHClCH.sub.2Cl HCFC-F242dc 0.4 0.2 0.1 0.1 CF.sub.2ClCHClCH.sub.2Cl

(5) The gaseous phase is analysed by GC and GC-MS. The compounds identified in the gaseous phase for Examples 1 to 4 are detailed in table 3 below.

(6) TABLE-US-00003 TABLE 3 Results obtained by on-line GC (mol %) for Examples 1-4 Products identified.sup.1 (mol %) Ex. 1 Ex. 2 Ex. 3 Ex. 4 HCFO-F1233xf 80 77 86 85 CF.sub.3CClCH.sub.2 HFO-F1243zf 13 11 9 8 CF.sub.3CHCH.sub.2 HCFO-F1231 and 7 6 4 3 HCFO-F1232 (sum of the isomers) Other compounds 0 6 1 4 including CO and CO.sub.2 .sup.1mol % of products mentioned is the mean value obtained over the duration of the reaction.