Process for purifying (hydro) fluoropropenes contaminated with halogenated ethane

Patent metadata

Field	Value
Publication number	US-10456730-B2
Application number	US-201515316978-A
Country	US
Kind code	B2
Filing date	Jun 9, 2015
Priority date	Jun 9, 2014
Publication date	Oct 29, 2019
Grant date	Oct 29, 2019

Abstract

A process for treating a composition comprising one or more desired (hydro)fluoroolefins and one or more undesired halogenated ethanes, halogenated methanes or mixtures thereof so as to reduce the concentration of at least one undesired halogenated ethane or halogenated methane, the process comprising contacting the composition with an adsorbent comprising pores having openings which have a size across their largest dimension of about 6 A or less.

First claim

The invention claimed is:

1. A process of purifying a tetrafluoropropene composition comprising: contacting the composition with an adsorbent, the composition composition at least one tetrafluoropropene and an impurity comprising 1,1,1,2-tetrafluoroethane (134a), the adsorbent comprising pores having openings which have a size across their largest dimension of about 6 Å or less, so as to remove at least a portion of the 134a from the composition.

2. A process according to claim 1 wherein the tetrafluoropropene comprises at least 10 wt % of the composition to be treated.

3. A process according to claim 1 wherein the adsorbent comprises having openings which have a size across their largest dimension of from about 4 Å to about 6 Å.

4. The process according claim 1 wherein the adsorbent is a molecular sieve.

5. The process according to claim 1 wherein the adsorbent comprises a zeolite.

6. The process according to claim 1 wherein the tetrafluoropropene is 2,3,3,3-tetrafluoropropene (1234yf).

7. The process according to claim 1 wherein the contacting step is performed, at least in part, at a temperature of from about 0° C. to about 200° C.

8. The process according to claim 1 wherein the contacting step is conducted at a pressure of from about 0.1 MPa to the saturation pressure.

9. The process according to claim 1 further comprising an adsorbent treatment step prior to the contacting step.

10. The process according to claim 9 wherein the adsorbent treatment step comprises a heat treatment step comprising heating the adsorbent to a maximum temperature of at least 150° C.

11. The process according to claim 10 wherein the heat treatment step comprising heating the adsorbent to a maximum temperature of at least 300° C.

12. The process according to claim 10 wherein the heat treatment step comprises maintaining the adsorbent at or around the maximum temperature for a time of from 1 second to 1 hour.

13. The process according to claim 10 wherein the adsorbent treatment step comprises an exposure step comprising exposing the adsorbent to one or more inert gases, or one or more noble gases performed before, during or after the heat treatment step.

14. The process according to claim 1 wherein the process removes at least 50% by weight of 134a.

15. The process according to claim 14 wherein the process reduces the concentration of 134a to levels at, around or below the limit of detection by gas chromatography.

16. The process according to claim 1 wherein the adsorbent is dried before use.

17. The process according to claim 1 wherein moisture content of the adsorbent is less than about 1.5% by weight.

18. The process according to claim 1 further comprising a step of regenerating the adsorbent after it has been contacted with the composition.

19. The process according to claim 18 wherein the regenerating step comprises contacting the adsorbent with a heated stream of inert gas and/or heating the adsorbent whilst the or an inert gas is passed over it.

20. The process according to claim 18 wherein the regenerating step comprises subjecting the adsorbent to a change in pressure.

21. The process according to claim 1 further comprising one or more additional purifying steps, which may be conducted before and/or after the contacting step.

22. The process according to claim 1 which is carried out, at least in part, in gas or liquid phase.

23. The method of claim 1 , further comprising removing the composition from a refrigerant system before contacting the composition with the absorbent.

Assignees

• Mexichem Fluor Sa De Cv

Inventors

• Sharratt Andrew
• Low Robert

Classifications

• Y02C20/30

  of perfluorocarbons [PFC], hydrofluorocarbons [HFC] or sulfur hexafluoride [SF6] · CPC title

• B01D2259/402

  using two beds · CPC title

• B01D2257/206

  Organic halogen compounds · CPC title

• B01D53/04

  with stationary adsorbents {(B01D53/025 takes precedence)} · CPC title

• B01D53/02 Primary

  by adsorption, e.g. preparative gas chromatography {(solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01)} · CPC title