Carbon cryogels and related methods

• US 20070113735A1
• Filed: 11/21/2005
• Published: 05/24/2007
• Est. Priority Date: 11/21/2005
• Status: Active Grant

• Current Assignee: BASF SE, Washington University In St Louis
• Original Assignee: EnerG2, Inc.
• Inventors: Cao, Guozhong, Feaver, Aaron
• Granted Patent: US 7,723,262 B2
• Time in Patent Office: Days
• US Class Current: 95/90
• CPC Class Codes: B01J 20/20 comprising free carbon; comprising carbon obtained by carbonising processes
• CPC Class Codes: B01J 20/28011 Other properties, e.g. density, crush strength
• CPC Class Codes: B01J 20/28047 Gels
• CPC Class Codes: B01J 20/28057 Surface area, e.g. B.E.T specific surface area
• CPC Class Codes: B01J 20/28076 being more than 1.0 ml/g
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01B 3/0021 Carbon, e.g. active carbon, carbon nanotubes, fullerenes; Treatment thereof
• CPC Class Codes: C01B 32/00 Carbon; Compounds thereof C01B21/00, C01B23/00 take precedence; percarbonates C01B15/10; carbon black C09C1/48
• CPC Class Codes: F17C 11/005 for hydrogen
• CPC Class Codes: F17C 11/007 for hydrocarbon gases, such as methane or natural gas, propane, butane or mixtures thereof [LPG]
• CPC Class Codes: Y02E 60/32 Hydrogen storage

Abstract

Carbon cryogels, methods for making the carbon cryogels, methods for storing a gas using the carbon cryogels, and devices for storing and delivering a gas using the carbon cryogels.

Claims

1. A carbon cryogel having a density of from about 0.20 to about 1.0 g/cm³, a surface area of from about 500 to about 3000 m²/g, a total pore volume of from about 1.0 to about 1.5 cm³/g, and a gas storage capacity of from about 0.0010 to about 0.015 mole/g at room temperature and at 500 psi.

2. The cryogel of claim 1, wherein the density is from about 0.25 to about 0.75 g/cm³.

3. The cryogel of claim 1, wherein the surface area is from about 1500 to about 3000 m²/g.

4. The cryogel of claim 1, wherein the pore volume is from about 1.2 to about 1.4 cm³/g.

5. The cryogel of claim 1, wherein the gas is selected from the group consisting of methane, hydrogen, nitrogen, carbon monoxide, fluorine, nitric oxide, nitrogen trifluoride, silane, ethylene, boron trifluoride, phosphine, arsine, disilane, and carbon tetrafluoride.

6. The cryogel of claim 1, wherein the gas storage capacity is from about 0.005 to about 0.015 mole/g.

7. A carbon cryogel obtainable by the process of:

(a) preparing a sol by mixing resorcinol, formaldehyde, and a catalyst in water;

(b) gelling the sol by heating at a temperature and for a time sufficient to provide a gel;

(c) washing the gel with acid to provide an acid-washed gel comprising an aqueous solvent;

(d) washing the acid-washed gel with a suitable organic solvent to exchange the aqueous solvent for an organic solvent to provide a solvent-exchanged gel;

(e) freeze drying the solvent-exchanged gel; and

(f) pyrolyzing the solvent-exchanged gel to provide a carbon cryogel, wherein the cryogel has a gas storage capacity of from about 0.0010 to about 0.015 mole/g.

8. A method for making a carbon cryogel, comprising:

(a) preparing a sol by mixing resorcinol, formaldehyde, and a catalyst in water;

(b) gelling the sol by heating at a temperature and for a time sufficient to provide a gel;

(c) washing the gel with acid to provide an acid-washed gel comprising an aqueous solvent;

(d) washing the acid-washed gel with a suitable organic solvent to exchange the aqueous solvent for an organic solvent to provide a solvent-exchanged gel;

(e) freeze drying the solvent-exchanged gel; and

(f) pyrolyzing the solvent-exchanged gel to provide a carbon cryogel.

9. The method of claim 8, further comprising heating the carbon cryogel at a temperature and for a time sufficient to provide an activated carbon cryogel.

10. The method of claim 9, wherein the temperature is about 900°

C. and the time is from about 10 to about 120 minutes.

11. The method of claim 9, wherein the activation is from about 5 to about 90%.

12. The method of claim 8, wherein the molar ratio of resorcinol to catalyst is from about 10 to about 300.

13. The method of claim 8, wherein the catalyst is sodium carbonate.

14. The method of claim 8, wherein the weight ratio of resorcinol to water is from about 0.01 to about 2.0.

15. The method of claim 8, wherein gelling the sol comprises heating at a temperature and for a period of time sufficient to convert the sol to a crosslinked gel.

16. The method of claim 8, wherein gelling the sol comprises heating at about 90°

C. for from about 1 to about 7 days.

17. The method of claim 8, wherein washing the gel with acid comprises washing the gel with aqueous trifluoroacetic acid.

18. The method of claim 8, wherein washing the acid-washed gel comprises washing the gel with t-butanol.

19. The method of claim 8, wherein pyrolyzing the solvent-exchanged gel comprises heating at a temperature and for a period of time sufficient to convert the gel to a carbon cryogel.

20. The method of claim 8, wherein pyrolyzing the solvent-exchanged gel comprises heating at about 1050°

C. for about 4 hours under nitrogen.

21. The method of claim 8, wherein heating at a temperature and for a time sufficient to provide an activated carbon cryogel comprises heating at about 900°

C. under carbon dioxide.

22. A method for gas storage, comprising contacting a vessel containing an adsorbate with a gas, wherein the adsorbate comprises a carbon cryogel having a density of from about 0.20 to about 1.0 g/cm³, a surface area of from about 500 to about 3000 m²/g, a total pore volume of from about 1.0 to about 1.5 cm³/g, and a gas storage capacity of from about 0.0010 to about 0.015 mole/g at room temperature and at 500 psi.

23. The method of claim 22, wherein the gas is methane.

24. A gas storage vessel, comprising a vessel and a carbon cryogel having a density of from about 0.20 to about 1.0 g/cm³, a surface area of from about 500 to about 3000 m²/g, a total pore volume of from about 1.0 to about 1.5 cm³/g, and a gas storage capacity of from about 0.0010 to about 0.015 mole/g at room temperature and at 500 psi.

25. A carbon cryogel having a surface area of from about 2000 to about 3000 m²/g.