Process for preparing C3-6(hydro)fluoroalkenes by dehydrohalogenating C3-6 halo(hydro)fluoroalkanes in the presence of a zinc/chromia catalyst

Patent metadata

Field	Value
Publication number	US-9567275-B2
Application number	US-201514876384-A
Country	US
Kind code	B2
Filing date	Oct 6, 2015
Priority date	Oct 3, 2006
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

The invention relates to a process for preparing a C3-6 (hydro)fluoroalkene comprising dehydrohalogenating a C3-6 hydro(halo)fluoroalkane in the presence of a zinc/chromia catalyst, wherein the C 3-6 (hydro)fluoroalkene produced is isomerized in the presence of the zinc/chromia catalyst.

First claim

We claim:

1. A process for preparing 2,3,3,3-tetrafluoropropene (CF3CF═CH2) comprising:
(i) fluorinating 3,3,3-trifluoro-2-chloropropene (CF3CCl═CH2) with HF in the vapour phase in the presence of a chromia-containing catalyst to produce an intermediate composition comprising 1,1,1,2-tetrafluoro-2-chloropropane (CF3CFClCH3) and 1,1,1,2,2-pentafluoropropane (CF 3 CF 2 CH 3 ); and
(ii) dehydrochlorinating the CF3CFClCH3 in the intermediate composition to produce CF3CF═CH2.

2. A process according to claim 1 , wherein step (ii) is carried out in the presence of a zinc/chromia catalyst.

3. A process according to claim 2 , wherein the zinc/chromia catalyst comprises 0.01 to 25% by weight zinc.

4. A process according to claim 2 , wherein the zinc/chromia catalyst is amorphous or from 0.1 to 50% by weight of the catalyst is in the form of one or more crystalline compounds of chromium and/or one or more crystalline compounds of zinc.

5. A process according to claim 1 , wherein CF3CFClCH3 is fluorinated to produce CF3CF2CH3.

6. A process according to claim 5 , wherein CF3CFClClH3 is fluorinated with HF in the presence of a chromia-containing catalyst to produce CF3CF2CH3.

7. A process according to claim 1 , wherein the CF3CF2CH3 is dehydrofluorinated to produce CF3CF═CH2.

8. A process according to claim 1 , wherein the ratio of HF:organics in the fluorinating step is from about 5:1 to about 30:1.

9. A process according to claim 1 , wherein the process is carried out at a temperature of greater than 300° C.

10. A process according to claim 1 , wherein the process is carried out at super-atmospheric pressure.

11. A process according to claim 1 , wherein the process is carried out at a pressure in the range from 1 to 5 bara.

12. A process according to claim 1 , wherein the catalyst is subsequently regenerated.

13. A process according to claim 12 , wherein the regeneration step is oxidative regeneration.

14. A process according to claim 1 , wherein the process is carried out with a diluent gas.

15. A process according to claim 14 , wherein the diluent gas comprises nitrogen.

16. A process according to claim 1 , wherein dehydrochlorination is carried out in the presence of a feed comprising hydrogen fluoride (HF).

17. A process according to claim 1 , wherein the dehydrochlorination is carried out in the absence of added hydrogen fluoride.

Assignees

• Mexichem Amanco Holding Sa

Inventors

• Sharratt Andrew Paul
• Seddon Leslie Richard

Classifications

• C07C17/04

  to unsaturated halogenated hydrocarbons · CPC title

• C07C19/01

  containing chlorine · CPC title

• C07C19/08

  containing fluorine · CPC title

• C07C17/087

  to unsaturated halogenated hydrocarbons · CPC title

• C07C19/10

  and chlorine · CPC title