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

1. A process for producing 2,3,3,3-tetrafluoropropene (1234yf) comprising:

introducing 1,1,1,2,3-pentachloropropane (240db) and/or 1,1,2,2,3-pentachloropropane (240aa), HF, and a first mixture comprising 1,1,1,2,2-pentafluoropropane (245cb), 2-chloro-3,3,3-trifluoropropene (1233xf) and 2,3,3,3-tetrafluoropropene (1234yf) into a gas phase fluorination reactor containing a fluorination catalyst, wherein at least a part of the 245cb introduced to the reactor is provided from a recycle loop, and

(ii) producing 1234yf and 1233xf in the reactor, wherein 1234yf and recycled 245cb form an equilibrium in the reactor thus resulting in increased production of 1234yf and a constant rate of 245cb in the recycle loop.

2. The process of claim 1 , wherein the 1,1,1,2,3-pentachloropropane (240db) and/or 1,1,2,2,3-pentachloropropane (240aa), HF, and first mixture are introduced to the reactor 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), the process further comprising;

(iii) 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

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

3. The process of claim 1 , wherein the process is carried out in a single stage.

4. The process of claim 1 , wherein the product 2,3,3,3-tetrafluoropropene is present at a concentration of at least 1%.

5. The process of claim 1 , wherein said catalyst is a chromium catalyst.

6. The 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.

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

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

9. The process of claim 1 , wherein the fluorination catalyst is activated with a fluorine-containing compound.

10. The process of claim 1 , wherein the 1,1,1,2,3-pentachloropropane contains up to 40 mol % of isomer 1,1,2,2,3-pentachloropropane.

11. The process of claim 1 , wherein the process is carried out at a pressure from 3 to 20 bars.

12. The process of claim 1 , wherein the process carried out at a temperature of from 200 to 450° C.

13. The process of claim 11 , wherein the process carried out at a temperature of 350 to 450° C.