Process for the preparation of 2,3,3,3 tetrafluoropropene

1. Process for preparing 2,3,3,3-tetrafluoropropene, comprising the steps:

(a) catalytic reaction of 1,1,1,2,3-pentachloropropane and/or 1,1,2,2,3-pentachloropropane with HF into 2-chloro-3,3,3-trifluoropropene; and

(b) catalytic reaction of said 2-chloro-3,3,3-trifluoropropene into 2,3,3,3-tetrafluoropropene, wherein step (b) comprises:

(i) contacting 2-chloro-3,3,3-trifluoro-1-propene with hydrogen fluoride in the gas phase in the presence of a fluorination catalyst under conditions sufficient to produce a reaction mixture;

(ii) separating the reaction mixture into a first stream comprising HCl, 2,2,2,3-tetrafluoropropene and a second stream comprising HF, unreacted 2-chloro-3,3,3-trifluoro-1-propene and 1,1,1,2,2-pentafluoropropane; and

(iii) recycling at least a part of the second stream back to step (i).

2. The process according to claim 1 , wherein the first stream is separated into HCl and 2,2,2,3-tetrafluoropropene.

3. The process according to claim 1 , wherein step (b) is carried out in the presence of a catalyst comprising Ni—Cr, preferably supported.

4. The process according to claim 3 , wherein said catalyst is supported on a support selected from fluorinated alumina, fluorinated chromia, fluorinated activated carbon or graphite carbon.

5. The process according to claim 1 , wherein step (a) is carried out in a liquid-phase.

6. The process according to claim 5 , wherein step (a) is carried out in an organic medium.

7. The process according to claim 6 , carried out in a solvent.

8. The process according to claim 7 , in which the solvent is selected from 1,2-dichloroethane, 1,2,3-trichloropropane, 1-chloro-1-fluoroethane, 1,1-difluoroethane, 1,1-dichloroethane, 1,3-dichloro-1-fluorobutane, tetrachlorofluoropropane isomers, trichlorodifluoropropane isomers, dichlorotrifluoropropane isomers, 1,1,1,3,3-pentafluorobutane, 1,1,2-trichloro-2,2-difluoroethane, nitrated solvents, 1,1,2-trichloro-2-fluoroethane, perchloroethylene, or mixtures thereof.

9. The process according to claim 5 in which the catalyst is an ionic liquid.

10. The process according to claim 5 , in which the 2-chloro-3,3,3-trifluoropropene is withdrawn in the gaseous state.

11. The process according to claim 5 , comprising:

contacting 1,1,1,2,3-pentachloropropane or/and 1,1,2,2,3-pentachloropropane with hydrogen fluoride in a liquid phase in an organic medium under conditions sufficient to form a reaction mixture comprising 2-chloro-3,3,3-trifluoropropene;

separating the reaction mixture into a first stream comprising HCl, and a second stream comprising HF and 2-chloro-3,3,3-trifluoropropene.

12. The process according to claim 1 , wherein step (a) is carried out in a gas-phase.

13. The process according to claim 12 , carried out in the presence of oxygen.

14. The process according to claim 12 , wherein step (a) is carried out in the presence of a catalyst comprising Ni—Cr, preferably supported.

15. The process according to claim 12 , wherein said catalyst is supported on a support selected from fluorinated alumina, fluorinated chromia, fluorinated activated carbon or graphite carbon.

16. The process according to claim 12 , wherein the temperature in step (b) is higher than the temperature of step (a) by at least 30° C.

17. The process according to claim 1 , in which said 1,1,1,2,3-pentachloropropane contains up to 40 mol % of 1,1,2,2,3-pentachloropropane.

18. The process according to claim 1 which is continuous.

19. The process according to claim 2 , wherein the separation into HCl and 2,2,2,3-tetrafluoropropene comprises a distillation step.

20. The process of claim 8 wherein said nitrated solvent is selected from nitromethane and nitrobenzene.

21. The process of claim 8 wherein said sulfone is selected from tetramethylene sulfone and dimethyl sulfone.