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

Patent metadata

Field	Value
Publication number	US-9957210-B2
Application number	US-201514876090-A
Country	US
Kind code	B2
Filing date	Oct 6, 2015
Priority date	May 15, 2008
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

The invention provides a process for the preparation of 1234yf comprising (a) contacting 1,1,2,3,3,3-hexafluoropropene (1216) with hydrogen in the presence of a hydrogenation catalyst to produce 1,1,2,3,3,3-hexafluoropropane (236ea); (b) dehydrofluorinating 236ea to produce 1,2,3,3,3-pentafluoropropene (1225ye); (c) contacting 1225ye with hydrogen in the presence of a hydrogenation catalyst to produce 1,2,3,3,3-pentafluoropropane (245eb); and (d) dehydrofluorinating 245eb to produce 1234yf.

First claim

We claim:

1. A process for the preparation of 2,3,3,3-tetrafluoropropene (1234yf), the process comprising:
(a) contacting 1,1,2,3,3,3-hexafluoropropene (1216) with hydrogen in the presence of a hydrogenation catalyst to produce 1,1,2,3,3,3-hexafluoropropane (236ea);
(b) dehydrofluorinating 236ea to produce 1,2,3,3,3-pentafluoropropene (1225ye);
(c) contacting 1225ye with hydrogen in the presence of a hydrogenation catalyst to produce 1,2,3,3,3-pentafluoropropane (245eb); and
(d) dehydrofluorinating 245eb to produce 1234yf,
wherein steps (a) and/or (c) is carried out with a diluent gas stream that comprises a molar excess of about 42% to 380% of feedstock 1216 and/or a molar excess of about 51 to 410% of feedstock 1225ye, respectively.

2. A process according to claim 1 wherein steps (a) and (c) are carried out in the same reactor, optionally wherein steps (a) and (c) are carried out simultaneously.

3. A process according to claim 1 wherein steps (b) and (d) are carried out in the same reactor, optionally wherein steps (b) and (d) are carried out simultaneously.

4. A process according to claim 1 , wherein steps (a) and (c) are carried out at a temperature of from −25 to 275° C. and a pressure of from 0 to 40 bara.

5. A process according to claim 1 , wherein steps (a) and (c) are carried out in the vapour phase at a temperature of from 0 to 250° C., optionally wherein steps (a) and (c) are carried out in the vapour phase at a temperature of from 20 to 200° C., preferably from 50 to 150° C.

6. A process according to claim 1 , wherein the hydrogenation catalyst in step (a) and wherein the hydrogenation catalyst in step (c) comprise a supported or unsupported transition metal selected from Ni, Pd, Pt, Re, Rh, Ru and mixtures thereof and is used in an amount of from 0.01 to 30% by weight based on the total weight of the components which make up steps (a) and (c).

7. A process according to claim 6 wherein the or each hydrogenation catalyst is supported on alumina, titania, silica, zirconia (or fluorides of the foregoing), calcium fluoride, carbon and/or barium sulphate, optionally wherein the or each hydrogenation catalyst is palladium supported on carbon (Pd/C).

8. A process according to claim 1 , wherein steps (b) and (d) are carried out at a temperature of from −70 to 1000° C. and a pressure of from 0 to 30 bara.

9. A process according to claim 1 , wherein steps (b) and (d) are carried out in the presence of a catalyst comprising activated carbon, a main group metal and/or a transition metal.

10. A process according to claim 9 , wherein steps (b) and (d) are carried out in the presence of a catalyst comprising a transition metal, optionally wherein the catalyst comprising a transition metal comprises chromia.

11. A process according to claim 1 , wherein steps (b) and (d) are carried out at a temperature of from 0 to 400° C. and a pressure of from 0.01 to 25 bara.

12. A process according to claim 1 , wherein steps (b) and (d) are carried out in the presence of a base.

13. A process according to claim 12 wherein steps (b) and (d) are carried out at a temperature of from −50 to 300° C.

14. A process according to claim 13 , wherein steps (b) and (d) are carried out at a temperature of from 20 to 250° C.

15. A process according to claim 12 wherein the base is selected from a metal hydroxide, a metal amide and mixtures thereof.

16. A process according to claim 12 wherein the base is an alkali metal hydroxide, optionally wherein the alkali metal hydroxide is selected from sodium hydroxide and potassium hydroxide.

17. A process according to claim 12 wherein the base is an alkaline earth metal hydroxide, optionally wherein the alkaline earth metal hydroxide is calcium hydroxide.

18. A process according to claim 17 , wherein steps (b) and (d) are carried out at a temperature of from 200 to 360° C. and a pressure of from 1 to 10 bara.

19. A process according to claim 12 wherein steps (b) and (d) are carried out in a solvent, optionally wherein the solvent is selected from water, alcohols, diols, polyols, polar aprotic solvents and mixtures thereof, optionally wherein the process is carried out in the presence of a co-solvent or diluent.

20. A process according to claim 19 wherein steps (b) and (d) are carried out in the presence of a catalyst, optionally wherein the catalyst is a crown ether or a quaternary ammonium salt.

Assignees

• Mexichem Amanco Holding Sa
• Mexichem Amanco Holdings S A De C V

Inventors

• Smith John W
• Mcguinness Claire
• Sharratt Andrew P
• Taylor Andrew M

Classifications

• C07C21/18

  containing fluorine · CPC title

• C07C17/354

  by hydrogenation · CPC title

• C07C17/25 Primary

  by splitting-off hydrogen halides from halogenated hydrocarbons · CPC title

• C07C19/08

  containing fluorine · CPC title

• C07C17/23

  by dehalogenation · CPC title