Glycerol dehydration methods and products thereof

Patent metadata

Field	Value
Publication number	US-9796648-B2
Application number	US-201515308016-A
Country	US
Kind code	B2
Filing date	May 4, 2015
Priority date	May 2, 2014
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

Methods and systems for suppressing coking in dehydration reactions catalyzed by solid acids. Dehydration reactions catalyzed by one or more solid acid catalysts can be performed in the presence of a super critical carbon dioxide medium which prevents or minimizes coking of the solid acid catalysts. Methods and systems are provided for producing glycerol products, such as acrolein, acrylic acid, acetol, by performing a dehydration reaction of glycerol using one or more solid acid catalysts in the presence of a super critical carbon dioxide reaction medium. Such methods and systems can be nm for extended periods of time, or continuously, due to catalyst regeneration and/or recycling. Such methods and systems are configured to produce glycerol products from crude glycerol feedstock with minimal pretreatment.

First claim

What is claimed is:

1. A method for producing a glycerol product, comprising exposing glycerol to a solid acid catalyst in a supercritical or subcritical carbon dioxide (SCF CO 2 ) reaction medium, whereby a glycerol product is produced by solid acid catalyzed dehydration of the glycerol.

2. The method of claim 1 , wherein coking of the solid acid catalyst is decreased during the solid acid catalyzed dehydration of the glycerol in the presence of SCF CO 2 as compared to solid acid catalyzed dehydration of glycerol in the absence of an SCF CO 2 reaction medium.

3. The method of claim 1 , wherein the active lifetime of the catalyst is extended as compared to the active lifetime of the catalyst during glycerol dehydration in a reaction medium other than SCF CO 2 .

4. The method of claim 1 , wherein the glycerol product is selected from the group consisting of acrolein, acrylic acid, acetol and combinations thereof.

5. The method of claim 1 , wherein the solid acid catalyst is selected from the group consisting of heteropoly acids, salts of heteropoly acids, zeolites, metal oxides, cation-exchange resins, carbonaceous solid acids, and combinations thereof.

6. The method of claim 1 , further comprising using co-solvent of water along with the SCF CO 2 .

7. The method of claim 1 , wherein the glycerol product comprises acrolein, wherein the method further comprises catalytic acrolein oxidation to acrylic acid, wherein the reaction medium for the catalytic acrolein oxidation comprises CO 2 or SCF CO 2 .

8. The method of claim 1 , wherein the glycerol comprises crude glycerol.

9. The method of claim 8 , wherein the crude glycerol comprises about 1 wt. % to about 100 wt. % glycerol, 0 wt. % to about 70 wt. % soapstock, 0 wt. % to about 30 wt. % alcohol, and about 1 wt. % to about 95 wt. % water content.

10. The method of claim 1 , further comprising a crude glycerol pretreatment step, comprising:
contacting the crude glycerol with activated charcoal; or
contacting the crude glycerol with an ion-exchange resin; or
a combination thereof.

11. The method of claim 10 , wherein the glycerol comprises about 0.025 wt. % to about 0.05% wt. % salt.

12. The method of claim 1 , further comprising:
mixing SCF CO 2 and glycerol and exposing the mixture to a temperature range of about 200° C. to 400° C. and a pressure range of 3 MPa to 35 MPa in a dehydration reactor comprising the solid acid catalyst to thereby produce acrolein; and
recovering the acrolein.

13. The method of claim 12 , wherein recovering the acrolein comprises fractional distillation.

14. The method of claim 1 , wherein SCF CO 2 comprises CO 2 having a critical temperature (T c ) greater than about 31.1° C. and a critical pressure (P c ) greater than about 7.38 MPa.

15. The method of claim 1 , further comprising the use of two catalysts, wherein a first catalyst comprises a dehydration catalyst that catalyzes the dehydration of glycerol to acrolein and wherein a second catalyst comprises a partial oxidation catalyst that catalyzes the oxidation of acrolein to acrylic acid, acetic acid, propionic acid and/or combinations thereof.

16. The method of claim 1 , further comprising recycling the catalyst, wherein recycling the active catalyst increases the active lifetime of the catalyst as compared to the active lifetime of the catalyst during glycerol dehydration in a reaction medium other than SCF CO 2 .

17. A reaction system for processing glycerol, comprising:
a conduit for transporting and mixing glycerol and reaction medium;
a CO 2 source;
a temperature and pressurization system for maintaining and controlling desired temperature and pressure, wherein the temperature and pressurization system comprises a heater and pressure pump sufficient to produce and maintain SCF CO 2 ;
a dehydration reactor; and
a distillation system,
wherein the temperature and pressurization system, dehydration reactor and distillation system are operably connected to or associated with the conduit to provide for the processing of glycerol.

18. The reaction system of claim 17 , wherein the dehydration reactor comprises one or more solid acid catalysts.

19. The reaction system of claim 17 , further comprising a source of pressurized oxygen or air.

20. The reaction system of claim 17 , wherein the reactor is a merged bed reactor comprising a dehydration catalyst and a partial oxidation catalyst.

21. The reaction system of claim 17 , wherein the reaction system is configured to be run continuously and wherein the reactor comprises a catalyst that is regenerated in the presence of SCF CO 2 .

22. The system of claim 17 , further comprising an apparatus for controlling the release of pressure and decrease of temperature.

23. A method of suppressing coking in dehydration reactions catalyzed by solid acids, comprising performing a dehydration reaction catalyzed by a solid acid catalyst in the presence of a SCF CO 2 medium, whereby coking of the solid acid catalyst is decreased when the reaction proceeds in the presence of the SCF CO 2 medium as compared to the same reaction in the absence of the SCF CO 2 medium.

24. The method of claim 22 , wherein a lifetime of the catalyst is increased as compared to the active lifetime of the catalyst during a dehydration reaction in a reaction medium that does not contain SCF CO 2 .

Assignees

• Univ Tennessee Res Found

Inventors

• Ye Xiaofei

Classifications

• B01J3/008

  Processes carried out under supercritical conditions · CPC title

• Y02P20/584

  Recycling of catalysts · CPC title

• B01J21/04

  Alumina · CPC title

• B01J23/8877

  Vanadium, tantalum, niobium or polonium · CPC title

• C07C51/235

  of —CHO groups or primary alcohol groups · CPC title