Porous carbons from carbohydrates

• US 20050207962A1
• Filed: 09/30/2004
• Published: 09/22/2005
• Est. Priority Date: 03/18/2004
• Status: Active Grant

• Current Assignee: Tda Research, Inc.
• Original Assignee: Tda Research, Inc.
• Inventors: Dietz, Steven, Recla, Dean
• Granted Patent: US 7,541,312 B2
• Time in Patent Office: Days
• US Class Current: 423/445.R
• CPC Class Codes: B01J 20/20 comprising free carbon; comprising carbon obtained by carbonising processes
• CPC Class Codes: B01J 20/28057 Surface area, e.g. B.E.T specific surface area
• CPC Class Codes: B01J 20/2808 being less than 2 nm, i.e. micropores or nanopores
• CPC Class Codes: B01J 20/28083 being in the range 2-50 nm, i.e. mesopores
• CPC Class Codes: B01J 20/3078 Thermal treatment, e.g. calcining or pyrolizing
• CPC Class Codes: C04B 35/52 based on carbon, e.g. graphite
• CPC Class Codes: C04B 35/528 obtained from carbonaceous particles with or without other non-organic components
• CPC Class Codes: C04B 35/6267 Pyrolysis, carbonisation or auto-combustion reactions
• CPC Class Codes: C04B 35/636 Polysaccharides or derivatives thereof
• CPC Class Codes: C04B 38/02 by adding chemical blowing agents
• CPC Class Codes: H01G 11/24 characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor
• CPC Class Codes: H01G 11/34 characterised by carbonisation or activation of carbon
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors

Abstract

A porous carbon characterized by a volumetric pore size distribution having two peaks, a first of said peaks being between 0.5 and 1.0 nm and a second of said peaks being between 1.0 and 5.0 nm. The porous carbon may have a volumetric capacitance in an organic electrolyte of at least 40 F/cm³, an average pore diameter between about 2 nm and about 30 nm, a surface area of at least 900 m²/g, and/or a density of at least 0.4 g/cm³. A method for making such a carbon includes a) curing a mixture comprising a carbohydrate, a dehydrating component, and a nonmetallic cationic pore-forming agent and b) carbonizing the cured carbon under conditions effective to provide a porous carbon having a surface area between about 100 m²/g and about 3000 m²/g. The the dehydrating component and nonmetallic cationic component may comprise two moieties of one compound.

Claims

1. A method of making a porous carbon comprising

(a) curing a mixture under conditions effective so as to produce a cured carbon, said mixture comprising:

(i) at least one carbohydrate,

(ii) at least one dehydrating component, and

(iii) at least one pore-forming agent comprising a nonmetallic cationic component; and

(b) carbonizing the cured carbon under conditions effective to provide a porous carbon having a surface area between about 100 m²/g and about 3000 m²/g.

2. The method according to claim 1 wherein step (a) includes removing substantially all of the water from the mixture.

3. The method according to claim 2 wherein step (a) includes producing a porous monolith.

4. The method according to claim 3, further including the step of grinding the porous monolith.

5. The method according to claim 1 wherein the dehydrating component and nonmetallic cationic component comprise two moieties of one compound.

6. The method according to claim 5 wherein the compound is selected from the group consisting of ammonium hydrogen sulfate ((NH₄)HSO₄), tetramethylammonium hydrogen sulfate (N(CH₄)₄HSO₄), tetraethylammonium hydrogen sulfate (N(CH₂CH₃)₄HSO₄), tetrapropylammonium hydrogen sulfate (N(CCH₂CH₂H₃)₄HSO₄), tetrabutylammonium hydrogen sulfate (N(CH₂CH₂CH₂CH₃)₄HSO₄), tetrahexylammonium hydrogen sulfate (N[(CH₂)₅CH₃]₄HSO₄), tetraheptylammonium hydrogen sulfate (N[(CH₂)₆CH₃]₄HSO₄), tetraoctylammonium hydrogen sulfate (N[(CH₂)₇CH₃]₄HSO₄), trimethyldodecylammonium hydrogen sulfate (CH₃(CH₂)₁₁N(CH₃)₃HSO₄), trimethyltetradecylammonium hydrogen sulfate (CH₃(CH₂)₁₃N(CH₃)₃HSO₄), trimethylhexadecylammonium hydrogen sulfate (CH₃(CH₂)₁₅N(CH₃)₃HSO₄), ammonium hydrogen oxalate ((NH₄)HC₂O₄), ammonium dihydrogenphosphate ((NH₄)H₂PO₄), ammonium hydrogen phosphate ((NH₄)₂HPO₄), and methyltrioctylammonium hydrogen sulfate (CH₃N[(CH₂)₇CH₃]₃HSO₄).

7. The method according to claim 1 wherein at least one nonmetallic cationic component comprises an ammonium cation.

8. The method according to claim 1 wherein said nonmetallic cationic component is substantially free of hydroxides and amines.

9. The method according to claim 1 wherein step (a) includes a first heating stage and a second heating stage.

16. The method according to claim 1 wherein step (a) comprises a single heating stage.

17. The method according to claim 1 wherein conditions for (a) curing a mixture include a pressure less than one atmosphere.

18. The method according to claim 1 wherein carbonization is carried out at a temperature between about 500°

C. and about 1200°

C. and for an interval of time between about 1 and about 4 hours.

19. The method according to claim 1 wherein carbonization is carried out under an inert atmosphere.

20. The method according to claim 1 wherein carbonization is carried out under a reduced pressure atmosphere.

21. The method according to claim 1 wherein carbonization is carried out at a furnace gas flow rate between about 0 oven vol/h and 16 oven vol/h.

22. The method according to claim 1 wherein carbonization is carried out at a furnace gas flow rate between about 0.5 oven vol/h and about 1.5 oven vol/h.

23. The method according to claim 1, further comprising an activation step.

24. The method according to claim 23 wherein said activation comprises treatment of said porous carbon with at least one selected from high-temperature steam, carbon dioxide, phosphoric acid, zinc chloride and potassium hydroxide.

25. The method according to claim 1 further comprising a ramp time for the carbonization step of at least 5 hours.

26. The method according to claim 1 further comprising a ramp time for the carbonization step of at least 10 hours.

27. The method according to claim 1 wherein said at least one carbohydrate is selected from the group consisting of glucose, fructose, maltose, sucrose, galactose, corn syrup, high-fructose corn syrup, starch, cellulose, and lactose, glyceraldehydes, dihydroxyacetone, and cellobiose.

28. The method according to claim 1 wherein said at least one carbohydrate is selected from the group consisting of sucrose, fructose and glucose.

29. The method according to claim 1 wherein at least one dehydrating component and at least one nonmetallic cationic component are from two separate compounds.

30. The method according to claim 29 wherein the dehydrating component is an acid.

31. The method according to claim 29 wherein the dehydrating component is selected from the group consisting of sulfuric, phosphoric, sulfurous, phosphorous, chlorous, hypochlorous, hypobromous, hypoiodous, periodic, perchloric, nitric, nitrous, iodic, hydrochloric, toluenesulfonic, oxalic, and methanesulfonic acids.

32. The method according to claim 31 wherein the ammonium cation has the formula NR¹R²R³R⁴,

wherein R¹, R², R³, and R⁴ may be the same or different and selected from the group consisting of H, CH₃, CH₂CH₃, CH₂CH₂CH₃, CH(CH₃)₂, CH₂(CH₂)₂CH₃, CH(CH₃)CH₂CH₃, CH₂CH(CH₃)₂, C(CH₃)₃, CH₂(CH₂)₁₄CH₃, CH₂(CH₂)₄CH₃, CH₂(CH₂)₅CH₃, CH₂(CH₂)₃CH₃, CH₂(CH₂)₆CH₃, CH₂(CH₂)₁₀CH₃, CH₂(CH₂)₁₂CH₃, and any combination thereof.

33. The method according to claim 27 wherein

(iii) at least one nonmetallic cationic component is from a compound selected from the group consisting of ammonium sulfate ((NH₄)₂SO₄), ammonium oxalate ((NH₄)₂C₂O₄), tetramethylammonium bromide (NMe₄Br), tetraethylammonium tetrafluoroborate (NEt₄BF₄), tetrapropylammonium bromide (NPr₄Br), tetrabutylammonium bromide (NBu₄Br), cetyltrimethylammonium bromide (CTAB), triethylamine hydrochloride (NEt₃.HCl), tetrahexylammonium chloride (N[(CH₂)₅CH₃]₄Cl), tetrapentylammonium bromide (N[(CH₂)₄CH₃]₄Br), tetraheptylammonium bromide (N[(CH₂)₆CH₃]₄Br), tetraoctylammonium bromide (N[CH₂)₇CH₃]₄Br), trimethyldodecyl-ammonium chloride (CH₃(CH₂)₁₁N(CH₃)₃Cl), trimethyltetradecylammonium bromide (CH₃(CH₂)₁₃N(CH₃)Br), trimethylhexadecylammonium chloride (CH₃(CH₂)₁₅N(CH₃)₃Cl) and methyltrioctylammonium chloride (CH₃N[(CH₂)₇CH₃]₃Cl) diaminobutane dihydrochloride (H₂N(CH₂)₄NH₂.2HCl), triphenylmethanol (C₆H₅)₃COH, polyethylenimine hydrochloride (H(—

NHCH₂CH₂—

)_nHN₂.XHCl, tetraethylphosphonium bromide (PEt₄Br) and tetramethylphosphonium chloride (PMe₄Cl).

34. A porous carbon made according to the method of claim 1.

35. The porous carbon according to claim 34 wherein said carbon is characterized by a volumetric pore size distribution having two peaks.

36. The porous carbon according to claim 35 wherein one of said peaks is between 0.5 and 1.0 nm and a second of said peaks is between 1.0 and 5.0 nm.

37. The porous carbon according to claim 35 wherein said carbon is further characterized by a volumetric capacitance measured in an organic electrolyte of at least 40 F/cm³.

38. The porous carbon according to claim 34 wherein said carbon is characterized by an average pore diameter between about 2 nm and about 30 mm.

39. The porous carbon according to claim 34 wherein the porous carbon is characterized by a surface area of at least 900 m 2/g.

40. The porous carbon according to claim 34 wherein the porous carbon is characterized by a density of at least 0.4 g/cm³.

41. The porous carbon according to claim 34 wherein the porous carbon is characterized by a volumetric capacitance measured in an organic electrolyte of at least 40 F/cm³.

42. The porous carbon according to claim 41 wherein the organic electrolyte comprises at least one selected from the group consisting of acetronitrile, propylene carbonate, dimethyl carbonate, and diethyl carbonate.

43. The porous carbon according to claim 34 wherein the porous carbon is characterized by a volumetric capacitance measured in an aqueous electrolyte of at least 80 F/cm³.

44. The porous carbon according to claim 43 wherein the aqueous electrolyte is selected from the group consisting of sodium chloride (NaCl), potassium hydroxide (KOH), and sulfuric acid (H₂SO₄).

45. The porous carbon according to claim 43 wherein the organic electrolyte comprises 1 M NEt₄BF₄ and 1:

1 dimethylcarbonate;

propylene carbonate.

46. A carbonaceous electrode comprising a carbon made according to the method of claim 1.

10. The method according to claim 10 wherein said first heating stage is executed before said second heating stage.

11. The method according to claim 10 wherein first heating stage is carried out at a temperature between about 80°

C. and about 120°

C. and lasts between about 1 and about 6 hours.

14. The method according to claim 10 wherein second heating stage is carried out at a temperature between about 140°

C. and about 200°

C. and lasts between about 1 and about 6 hours.

15. The method according to claim 10 wherein at least one of said stages is carried out in an atmosphere selected from the group consisting of nitrogen, argon, air and combinations thereof.

12. The method according to claim 12 wherein first heating stage further includes forming the material from the first heating stage into pellets.

13. The method according to claim 12 wherein first heating stage further includes washing the material from the first heating stage with water.

47. A porous carbon characterized by a volumetric pore size distribution having two peaks, wherein a first one of said peaks is between 0.5 and 1.0 nm and a second of said peaks is between 1.0 and 5.0 nm.

48. The porous carbon according to claim 47 wherein said carbon is further characterized by a volumetric capacitance measured in an organic electrolyte of at least 40 F/cm³.

49. The porous carbon according to claim 47 wherein said carbon is further characterized by an average pore diameter between about 2 nm and about 30 nm.

50. The porous carbon according to claim 47 wherein the porous carbon is characterized by a surface area of at least 900 m²/g.

51. The porous carbon according to claim 47 wherein the porous carbon is characterized by a density of at least 0.4 g/cm³.