PROCESS FOR PRODUCING 1-CHLORO-2,2-DIFLUOROETHANE

Abstract

The present invention relates to the field of saturated fluorohydrocarbons. The subject matter thereof is more particularly the production of 1-chloro-2,2-difluoroethane from 1,1,2-trichloroethane and/or 1,2-dichloroethylene. A process for producing 1-chloro-2,2-difluoroethane from 1,1,2-trichloroethane and/or 1,2-dichloroethylene including (i) at least one step during which the 1,1,2-trichloroethane and/or the 1,2-dichloroethylene reacts or react with hydrofluoric acid in the gas phase, optionally in the presence of an oxidizing agent, in the presence or in the absence of a fluorination catalyst, to give a stream including 1-chloro-2,2-difluoroethane, hydrochloric acid, hydrofluoric acid and at least one C compound(s) chosen from 1-chloro-2-fluoroethylenes (cis and trans), 1,2-dichloro-2-fluoroethane and, optionally, unreacted 1,1,2-trichloroethane and/or 1,2-dichloroethylene.

Claims

1. A process for manufacturing 1-chloro-2,2-difluoroethane from 1,1,2-trichloroethane and/or 1,2-dichloroethylene, comprising at least one step during which 1,1,2-trichloroethane and/or 1,2-dichloroethylene react(s) with hydrofluoric acid in the gas phase optionally in the presence of an oxidizing agent, and in the presence or absence of a fluorination catalyst, to give a stream comprising 1-chloro-2,2-difluoroethane, hydrochloric acid, hydrofluoric acid and at least one compound C chosen from 1-chloro-2-fluoroethylenes (cis and trans), 1,2-dichloro-2-fluoroethane and optionally unreacted 1,1,2-trichloroethane and/or 1,2-dichloroethylene.

2. A process for manufacturing 1-chloro-2,2-difluoroethane from 1,1,2-trichloroethane, comprising: (i) at least one step during which 1,1,2-trichloroethane reacts with hydrofluoric acid in the gas phase optionally in the presence of an oxidizing agent, and in the presence or absence of a fluorination catalyst, to give a stream comprising 1-chloro-2,2-difluoroethane, hydrochloric acid, hydrofluoric acid and at least one compound C chosen from 1,2-dichloroethylenes (cis and trans), 1-chloro-2-fluoroethylenes (cis and trans), 1,2-dichloro-2-fluoroethane and optionally unreacted 1,1,2-trichloroethane; (ii) at least one step of separating the compounds derived from the reaction step to give a stream A comprising hydrochloric acid and a stream B comprising hydrofluoric acid, 1-chloro-2,2-difluoroethane, at least one compound C and optionally 1,1,2-trifluoroethane; (iii) at least one step of separating the stream B to give an organic phase comprising 1-chloro-2,2-difluoroethane, at least one compound C and optionally unreacted 1,1,2-trichloroethane and a non-organic phase predominantly comprising HF; (iv) at least one step of separating the 1-chloro-2,2-difluoroethane from the organic phase obtained in (iii); (v) optionally, recycling into step (i) of the organic phase after the separation of step (iv); and (vi) optionally, recycling into step (i) of the non-organic phase derived from step (iii).

3. The process as claimed in claim 2, wherein, after the step of separating out the 1-chloro-2,2-difluoroethane, the organic phase comprises 1-chloro-2-fluoroethylene, 1,2-dichloroethylenes (cis and trans) and 1,2-dichloro-2-fluoroethane.

4. The process as claimed in claim 2, wherein the non-organic phase derived from step (iii) is purified such that the HF content is greater than or equal to 90% by weight before recycling into step (i).

5. The process as claimed in claim 4, wherein the purification comprises at least one distillation, performed at a temperature of between −23 and 46° C. and an absolute pressure of between 0.3 and 3 bar.

6. The process as claimed in claim 2, wherein the separation step (ii) comprises at least one distillation, performed at a temperature of between −60 and 120° C. and an absolute pressure of between 3 and 20 bar.

7. The process as claimed in claim 2, wherein the separation step (iii) comprises at least one decantation step, preferably performed at a temperature of between −20 and 60° C.

8. The process as claimed in claim 2, wherein the separation step (iv) comprises at least one distillation, performed at a temperature of between 35 and 79° C. and an absolute pressure of between 0.3 and 4 bar.

9. The process as claimed in claim 1, wherein the temperature of the reaction step is between 150 and 400° C.

10. The process as claimed in claim 1, wherein the pressure at which the fluorination reaction is performed is between 1 and 20 bar absolute.

11. The process as claimed in claim 1, wherein the amount of hydrofluoric acid used in the reaction is between 5 and 40 mol per mole of HCC-140 and/or 1,2-dichloroethylene.

12. The process as claimed in claim 1, wherein the oxidizing agent may be chosen from oxygen and chlorine.

13. The process as claimed in claim 12, wherein the amount of oxidizing agent used is between 0.01 mol % and 20 mol % per mole of HCC-140 and/or 1,2-dichloroethylene.

14. A composition of the azeotropic or quasi-azeotropic type comprising 1-chloro-2,2-difluoroethane and trans-1,2-dichloroethylene.

15. The composition as claimed in claim 14, comprising from 80 mol % to 95 mol % of 1-chloro-2,2-difluoroethane and from 5 mol % to 20 mol % of trans-1,2-dichloroethylene.

16. The composition as claimed in claim 14, wherein, the boiling point is between 32 and 119° C. at a pressure of between 1 and 10 bar abs.

Description

EXAMPLES

[0043] Experimental Procedure:

[0044] HCC-140 and optionally 1,2-dichloroethylene and HF are fed separately into a monotubular Inconel reactor, heated by means of a fluidized alumina bath.

[0045] The pressure is regulated by means of a regulation valve located at the reactor outlet. The gases derived from the reaction are analyzed by gas chromatography.

[0046] The catalyst is first dried under a stream of nitrogen at 250° C. and the nitrogen is then gradually replaced with HF to terminate the activation with pure HF (0.5 mol/hour) at 350° C. for 8 hours.

Example 1

[0047] The catalyst used is a chromium oxide (Cr.sub.2O.sub.3). 35 g are activated as described above. HCC-140 and HF are then fed in at a mole ratio of 1:8 (10 g/hour of HF), at 230° C., 11 bar abs, with a contact time of 65 seconds.

[0048] The yield of F142 is 70% after 5 hours. After 30 hours, the yield is less than 30%.

Example 2

[0049] The catalyst used is a chromium oxide (Cr.sub.2O.sub.3) as in Example 1. 55 g are activated as described above. HCC-140, HF and chlorine are then fed in at an HCC-140/HF/chlorine mole ratio of 1:9:0.08 (17 g/hour of HF), at 230° C., 11 bar abs, with a contact time of 54 seconds.

[0050] The yield of F142 is 60% after 5 hours. After 100 hours, the yield is 62%.

Example 3

[0051] The catalyst used is a chromium oxide (Cr.sub.2O.sub.3) as in Example 1. 35 g are activated as described above. HCC-140, HF and chlorine are then fed in at an HCC-140/HF/chlorine mole ratio of 1:20:0.08 (30 g/hour of HF), at 225° C., 3 bar abs, with a contact time of 4 seconds.

[0052] The yield of F142 is 50% stable over a period of 500 hours.

Example 4

[0053] The catalyst used is a chromium oxide (Cr.sub.2O.sub.3) supported on alumina. 27 g are activated as described above. HCC-140 and HF are then fed in at an HCC-140/HF mole ratio of 1:8 (10 g/hour of HF), at 235° C., 11 bar abs, with a contact time of 45 seconds.

[0054] The yield of F142 is 70% after 5 hours. After 30 hours, the yield is less than 30%.

TABLE-US-00001 Example 1 2 3 4 Catalyst Bulk Cr Bulk Cr Bulk Cr Cr oxide oxide oxide oxide on alumina Amount (g) 35 55 35 27 HF/T112 mole ratio 8 9 20 8 HF (g/hour) 10 17.5 30 10 Chlorine/T112 mole 0 0.08 0.08 0 ratio T (° C.) 230 230 225 235 P (bar abs) 11 11 3 11 Contact time (seconds) 65 54 4 45 Yield (%) after 5 hours 70 60 53 70 Yield (%) after 30 hours <30 61 <30 Yield (%) after 100 hours <10 62 Yield (%) after 500 hours 50

Example 5

[0055] No catalyst is used. HCC-140 and HF are fed in at an HCC-140/HF mole ratio of 1:20 (30 g/hour of HF), at 225° C., 11 bar abs, with a contact time of 50 seconds.

[0056] The yield of F142 is 25% stable over a period of 500 hours.