Catalytic gas phase fluorination

1. A process for producing 2,3,3,3-tetrafluoropropene, comprising:

an activation stage comprising two successive steps:

i) contacting a fluorination catalyst with hydrogen fluoride and 2-chloro-3,3,3-trifluoro-1-propene or 1,1,1,2,3-pentachloropropane or 1,1,2,3-tetrachloropropene or 2,3,3,3-tetrachloropropene; and

ii) contacting the fluorination catalyst with an oxidizing agent-containing gas flow; and

at least one reaction stage comprising reacting 2-chloro-3,3,3-trifluoro-1-propene or 1,1,1,2,3-pentachloropropane with hydrogen fluoride in the gas phase in the presence of the activated fluorination catalyst, so as to produce 2,3,3,3-tetrafluoropropene.

2. The process of claim 1 , wherein the activation stage and the reaction stage take place in a single reactor.

3. The process of claim 1 , further comprising a regeneration stage, wherein the regeneration stage comprises contacting the fluorination catalyst with an oxidizing agent-containing gas flow.

4. The process of claim 3 , wherein the oxidizing agent-containing gas flow of the regeneration stage is an oxygen-containing gas flow.

5. The process of claim 3 , wherein the regeneration stage comprises contacting the fluorination catalyst with the oxidizing agent-containing gas flow for at least 2 hours.

6. The process of claim 3 , wherein the oxidizing agent-containing gas flow of the regeneration stage contains hydrogen fluoride in addition to the oxidizing agent, and wherein the proportion of oxidizing agent in the oxidizing agent-containing gas flow of the regeneration stage is from 2 to 98 mol %, relative to the total amount oxidizing agent and hydrogen fluoride.

7. The process of claim 3 , wherein the oxidizing agent-containing gas flow of the regeneration stage does not contain hydrogen fluoride.

8. The process of claim 7 , wherein the oxidizing agent-containing gas flow of the regeneration stage is air.

9. The process of claim 3 , wherein the regeneration stage comprises contacting the fluorination catalyst with a hydrogen fluoride gas flow, either:

before contacting the fluorination catalyst with the oxidizing agent-containing gas flow; or

after contacting the fluorination catalyst with the oxidizing agent-containing gas flow.

10. The process of claim 3 , wherein the oxidizing agent-containing gas flow is contacted with the fluorination catalyst during the regeneration stage at a temperature of from 250 to 500° C.

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

12. The process of claim 1 , wherein the fluorination catalyst is an unsupported catalyst.

13. The process of claim 1 , wherein the fluorination catalyst further comprises a co-catalyst comprising Co, Zn, Mn, Mg, V, Mo, Te, Nb, Sb, Ta, P, Ni or mixtures thereof, and wherein said co-catalyst is present in an amount from about 1-10 wt % of said fluorination catalyst.

14. The process of claim 1 , wherein the fluorination catalyst is a mixed chromium/nickel catalyst, the atomic ratio of nickel to chromium being from 0.5 to 2.

15. The process of claim 1 , wherein the molar ratio of hydrogen fluoride to 2-chloro-3,3,3-trifluoro-1-propene is from 3:1 to 150:1.

16. The process of claim 1 , wherein the reaction stages are carried out at a pressure of from 1 to 20 bars.

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

18. The process of claim 1 , wherein the contact time between hydrogen fluoride and the chlorinated compound during the reaction stages is from 6 to 100 s.

19. The process of claim 1 , wherein the reaction stages are carried out in the presence of oxygen as the oxidizing agent, the ratio of oxygen being from 0.05 to 15 mole %, with respect to the total amount of 2-chloro-3,3,3-trifluoro-1-propene or 1,1,1,2,3-pentachloropropane and oxygen.