Mesophase pitch for carbon fiber production using supercritical carbon dioxide

Patent metadata

Field	Value
Publication number	US-11725146-B2
Application number	US-202217874832-A
Country	US
Kind code	B2
Filing date	Jul 27, 2022
Priority date	Mar 18, 2019
Publication date	Aug 15, 2023
Grant date	Aug 15, 2023

Abstract

Embodiments of methods for improving mesophase pitch for carbon fiber production using supercritical carbon dioxide are described. The methods improve the relative amount and quality of mesophase pitch in feedstocks, such as coal tar, already having at least some mesophase pitch. One particular method includes performing a sCO2/toluene extraction on the coal tar to obtain a toluene insoluble fraction of the coal tar; mixing the toluene insoluble fraction with sCO2 to obtain a sCO2/toluene insoluble fraction mixture; and extruding the sCO2/toluene insoluble fraction mixture, thereby separating the sCO2 from the toluene insoluble fraction to obtain fibers of mesophase pitch.

First claim

What is claimed:

1. A method of manufacturing carbon fibers comprising:
contacting coal tar containing at least some mesophase pitch precursor with a supercritical fluid solvent and first co-solvent mixture, thereby removing at least some soluble components from the coal tar to obtain an insoluble coal tar fraction;
after the contacting operation, separating the supercritical fluid solvent and first co-solvent mixture from the insoluble coal tar fraction;
after the separating operation, mixing the insoluble coal tar fraction with sCO 2 to obtain a sCO 2 /insoluble fraction mixture; and
passing the sCO 2 /insoluble fraction mixture through an extruder, thereby separating the sCO 2 from the insoluble fraction to obtain fibers of mesophase pitch.

2. The method of claim 1 further comprising:
washing the insoluble fraction with a second co-solvent to obtain a second co-solvent and second co-solvent-soluble fraction mixture and a second co-solvent-insoluble fraction of the first insoluble fraction;
separating the second co-solvent from the second co-solvent-soluble fraction of the insoluble fraction; and
mixing the second co-solvent-soluble fraction of the insoluble fraction with sCO 2 to obtain the sCO 2 /insoluble fraction mixture;
wherein the second co-solvent is selected from one or more of benzene, xylene, tetralin, tetrahydrofuran, pyridine, and quinoline.

3. The method of claim 2 further comprising:
heating the second co-solvent-soluble fraction of the insoluble fraction to from 300 to 400° C. for less than 24 hours before mixing the second co-solvent-soluble fraction with sCO 2 .

4. The method of claim 3 , wherein the heating operation further comprises:
contacting the second co-solvent-soluble fraction with sCO 2 heated to a temperature between 300 to 400° C. for up to 24 hours.

5. The method of claim 1 further comprising:
performing a stabilization operation on the fibers of mesophase pitch.

6. The method of claim 1 further comprising:
performing a carbonization operation on the fibers of mesophase pitch.

7. The method of claim 1 further comprising:
performing a graphitization operation on the fibers of mesophase pitch.

8. The method of claim 1 wherein the supercritical fluid solvent is selected from one or more of carbon dioxide, water, methane, nitrous oxide, ethane, propane, ethylene, propylene, methanol, ethanol, and acetone.

9. The method of claim 1 wherein the first co-solvent is an aromatic organic solvent.

10. The method of claim 2 wherein the second co-solvent is an aromatic organic solvent.

11. The method of claim 1 wherein the first co-solvent is selected from one or more of benzene, xylene, tetralin, tetrahydrofuran, pyridine, and quinoline.

12. The method of claim 1 wherein the second co-solvent is selected from one or more of benzene, xylene, tetralin, tetrahydrofuran, pyridine, and quinoline.

13. The method of claim 1 wherein the coal tar is created by:
pyrolyzing a combination of carbonaceous feedstock at a first temperature and first pressure and for a first period of time to generate C 1 -C 4 gases;
increasing the combination to a second temperature greater than the first temperature;
pyrolyzing the combination at the second temperature and for a second period of time to generate coal tar; and
extracting coal tar from the combination.

14. The method of claim 13 wherein the first temperature is from 150-350° C. and the first pressure is from 7-30 MPa.

15. The method of claim 13 wherein the second temperature is from 350-550° C.

16. The method of claim 13 wherein the first period is from 1 to 120 minutes.

17. The method of claim 13 wherein the first period is determined based on the amount of at least one C 1 -C 4 gas generated at the first temperature from the carbonaceous feedstock.

18. The method of claim 13 wherein the second period of time is from 1 minute to 24 hours.

19. The method of claim 13 wherein pyrolyzing the carbonaceous feedstock at the first temperature and first pressure is performed in a first pyrolysis reaction chamber.

20. The method of claim 13 wherein pyrolyzing the carbonaceous feedstock at the second temperature is performed in the first pyrolysis reaction chamber.

21. The method of claim 13 wherein pyrolyzing the carbonaceous feedstock at the second temperature is performed in a second pyrolysis reaction chamber different from the first pyrolysis reaction chamber.

22. The method of claim 13 wherein pyrolyzing the carbonaceous feedstock at the first temperature and first pressure is performed in a carbon dioxide atmosphere.

23. The method of claim 13 further comprising:
monitoring a concentration of one or more C 1 -C 4 gases in the pyrolysis atmosphere.

24. The method of claim 23 wherein extracting the coal tar includes transferring the carbon dioxide atmosphere to a separation system.

25. The method of claim 23 wherein extracting the coal tar includes lowering at least one of the temperature or the pressure of the carbon dioxide atmosphere.

26. The method of claim 1 wherein the supercritical fluid solvent is supercritical carbon dioxide, the first co-solvent is toluene, and the second co-solvent is quinoline.

Assignees

• Terrapower Llc

Inventors

• Goodrich Benjamin L
• Kim Pyoungchung
• Targett Matthew
• Walter Joshua C

Classifications

• D01F9/145

  from pitch or distillation residues · CPC title

• D01F9/15

  from coal pitch · CPC title

• C10C3/08 Primary

  by selective extraction · CPC title

• C10C1/18 Primary

  by extraction with selective solvents (preparation of hydrocarbon oils from tar oils C10G21/00) · CPC title

• Y02P20/54

  using solvents, e.g. supercritical solvents or ionic liquids · CPC title