Process for the manufacture of 2,3,3,3-tetrafluoropropene by gas phase fluorination of pentachloropropane

1. A process of producing 2,3,3,3-tetrafluoropropene comprising

(i) contacting 1,1,1,2,3-pentachloropropane and/or 1,1,2,2,3-pentachloropropane with hydrogen fluoride in gas phase in the presence of a fluorination catalyst under conditions sufficient to produce a reaction mixture comprising 2,3,3,3-tetrafluoropropene (1234yf), 2-chloro-3,3,3-trifluoro-1-propene (1233xf) and 1,1,1,2,2-pentafluoropropane (245cb);

(ii) separating the reaction mixture into a first stream comprising 2,3,3,3 tetrafluoropropene (1234yf) and a second stream comprising 2-chloro-3,3,3-trifluoro-1-propene (1233xf) and 1,1,1,2,2-pentafluoropropane (245cb); and

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

2. Process according to claim 1 , wherein the process is carried out in a single stage.

3. Process according to claim 1 , wherein the product 2,3,3,3-tetrafluoropropene is present at a concentration of at least 1%.

4. Process of claim 1 , wherein said catalyst is a chromium catalyst.

5. Process of claim 4 , wherein said catalyst further comprises a co-catalyst selected from the group consisting of Ni, Co, Zn, Mn, Mg and mixtures thereof, and wherein said co-catalyst is present in an amount from about 1-10 wt % of said fluorination catalyst.

6. Process of claim 1 , wherein the process is carried out in the presence of a catalyst comprising Ni—Cr.

7. Process of claim 1 , wherein said catalyst is supported on a support comprising fluorinated alumina, fluorinated chromia, fluorinated activated carbon or graphite carbon.

8. Process of claim 1 , wherein the fluorination catalyst is activated with a fluorine-containing compound.

9. Process of claim 1 , in which the 1,1,1,2,3-pentachloropropane contains up to 40 mol % of isomer 1,1,2,2,3-pentachloropropane.

10. Process of claim 1 , wherein the process is carried out with a contact time from 6 to 100 sec.

11. Process of claim 1 , wherein the process is carried out with a molar ratio HF:(240db and/or 240aa) from 3:1 to 150:1.

12. Process of claim 1 , wherein the process is carried out in the presence of a polymerization inhibitor.

13. The process of claim 12 , wherein the polymerization inhibitor is selected from the group consisting of p-methoxyphenol, t-amylphenol, limonene, quinones, hydroquinones, epoxides, amines and mixtures thereof.

14. Process of claim 1 , wherein the process is carried out in the presence of oxygen and/or chlorine.

15. Process according to claim 14 , wherein the process is carried out in the presence of oxygen and/or chlorine in an amount of from 0.05 to 15 mole %, of oxygen or chlorine per pentachloropropane molecule.

16. Process according to claim 1 , wherein the first stream is further separated into HCl and 2,3,3,3-tetrafluoropropene (1234yf).

17. Process of claim 1 , wherein the separating step is a distillation step.

18. The process of claim 1 , wherein the process is continuous.

19. Process of claim 1 , which is carried out at a pressure from 3 to 20 bars.

20. Process of claim 1 , carried out at a temperature of from 200 to 450° C.

21. A process of producing 2,3,3,3-tetrafluoropropene comprising:

(i) contacting 1,1,1,2,3-pentachloropropane (HCC 240db) and/or 1,1,2,2,3 pentachloropropane (HCC 240aa) with hydrogen fluoride (HF) in gas phase in the presence of a fluorination catalyst under conditions sufficient to produce a reaction mixture comprising 2,3,3,3-tetrafluoropropene (1234yf), HCl, HF, 2-chloro-3,3,3-trifluoro-1-propene (1233xf) and 1,1,1,2,2-pentafluoropropane (245cb);

(ii) separating the reaction mixture into a first stream comprising HCl, 2,3,3,3tetrafluoropropene (1234yf) and a second stream comprising HF, 2-chloro-3,3,3-trifluoro-1-propene (1233xf) and 1,1,1,2,2-pentafluoropropane (245cb); and

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

22. A process of producing 2,3,3,3-tetrafluoropropene comprising:

(i) contacting 1,1,1,2,3-pentachloropropane (HCC 240db) and/or 1,1,2,2,3 pentachloropropane (HCC 240aa) with hydrogen fluoride HF in gas phase in the presence of a fluorination catalyst under conditions sufficient to produce a reaction mixture comprising 2,3,3,3-tetrafluoropropene (1234yf), HCl, HF, 2-chloro-3,3,3-trifluoro-1-propene (1233xf) and 1,1,1,2,2 pentafluoropropane (245cb);

(ii) separating the reaction mixture into HCl and a stream containing the fluorinated products;

(iii) separating said stream containing the fluorinated products into a first stream comprising 2,3,3,3-tetrafluoropropene (1234yf) and a second stream comprising HF, 2-chloro -3,3,3-trifluoro-1-propene (1233xf) and 1,1,1,2,2 pentafluoropropane (245cb); and

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