Varied morphology carbon nanotubes and method for their manufacture

• US 20030004058A1
• Filed: 05/20/2002
• Published: 01/02/2003
• Est. Priority Date: 05/21/2001
• Status: Active Grant

• Current Assignee: Trustees of Boston College (Boston College)
• Original Assignee: Trustees of Boston College (Boston College)
• Inventors: Li, Wenzhi, Ren, Zhi Feng, Wen, Jian Guo
• Granted Patent: US 7,157,068 B2
• Time in Patent Office: Days
• US Class Current: 502/258
• CPC Class Codes: B01J 23/745 Iron
• CPC Class Codes: B01J 23/75 Cobalt
• CPC Class Codes: B01J 37/036 to form a gel or a cogel
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 32/162 characterised by catalysts
• CPC Class Codes: D01F 9/127 by thermal decomposition of hydrocarbon gases or vapours or other carbon-containing compounds in the form of gas or vapour, e.g. carbon monoxide, alcohols
• CPC Class Codes: Y10S 977/843 Gas phase catalytic growth, i.e. chemical vapor deposition

Abstract

The present invention describes the preparation of carbon nanotubes of varied morphology, catalyst materials for their synthesis. The present invention also describes reactor apparatus and methods of optimizing and controlling process parameters for the manufacture carbon nanotubes with pre-determined morphologies in relatively high purity and in high yields. In particular, the present invention provides methods for the preparation of non-aligned carbon nanotubes with controllable morphologies, catalyst materials and methods for their manufacture.

Claims

1. A process for preparation of non-aligned carbon nanotubes in a reaction vessel comprising steps of:

providing, in a reactor, a catalyst material in the form of catalytic particles, said catalyst material including a catalyst substrate material;

creating a substantially oxygen free atmosphere in the reactor and controlling the pressure within said reactor;

feeding at least one carbon source gas into the reactor;

providing thermal energy to heat the reactor to a reaction temperature sufficient to cause the carbon-based gas to form nucleated tubules in the presence of the catalytic particles and cause the initiation of tubule growth into carbon nanotubes;

optionally feeding at least one promoter gas into the reactor to promote carbon nanotube growth; and

optionally feeding a mixture of gases comprising a promoter gas and at least one diluent gas in order regulate carbon nanotube growth.

2. The process of claim 1 wherein the carbon source gas is a saturated or unsaturated linear hydrocarbon, branched hydrocarbon, cyclic hydrocarbon or a mixture thereof.

3. The process of claim 1 wherein the carbon source gas is selected from the group consisting of methane, n-propane, ethylene, acetylene, benzene carbon dioxide, natural gas, coal derivative gases and mixtures thereof.

4. The process of claim 3 wherein the carbon source gas is acetylene.

5. The process of claim 1 wherein the catalyst substrate material is a mesoporous sol-gel material impregnated with or having deposited thereon a metallic material.

6. The process of claim 5 wherein the mesoporous sol-gel material is mesoporous silica, mesoporous alumina or mixtures thereof.

7. The process of claim 5 wherein the metallic material is a transition metal, metal alloy or a combination thereof.

8. The process of claim 5 wherein the metallic material is selected from the group consisting of iron, cobalt, nickel and combinations thereof.

9. The process of claim 5 wherein the metallic material is iron or cobalt.

10. The process of claim 1 wherein the catalyst substrate material comprises a metallic material and at least one non-metallic material.

11. The process of claim 10 wherein the metallic material is a transition metal, metal alloy or a combination thereof.

12. The process of claim 10 wherein the metallic material is selected from the group consisting of iron, cobalt, nickel and combinations thereof.

13. The process of claim 10 wherein the metallic material is cobalt.

14. The process of claim 10 wherein the non-metallic material is an organic or inorganic oxide, nitride, sulfide or carbide compound.

15. The process of claim 14 wherein the non-metallic compound is a metal oxide selected from the group consisting of beryllium oxide, magnesium oxide, calcium oxide, strontium oxide and barium oxide.

16. The process of claim 14 wherein the non-metallic material is magnesium oxide.

17. The process of claim 10 wherein the non-metallic material is an organo-metallic material.

18. The process of claim 17 wherein the non-metallic material is a metallocene.

19. The process of claim 18 wherein the non-metallic material is selected from the group consisting of ferrocene, nickelocene, cobaltocene, a ferrocene-xylene mixture and mixtures thereof.

20. The process of claim 10 wherein the non-metallic material comprises a mixture of an organo-metallic material and at least one metal oxide compound.

21. The process of claim 1 wherein the promoter gas is ammonia, ammonia-nitrogen, hydrogen, thiophene, iron pentacarbonyl or mixtures thereof.

22. The process of claim 1 wherein the promoter gas is ammonia.

23. The process of claim 1 wherein the promoter gas is diluted by mixing it with a diluter gas chosen from the group consisting of hydrogen, nitrogen, argon, neon, krypton, xenon hydrogen sulfide, or any combination thereof.

24. The process of claim 1 wherein the reduced pressure measures from about 10⁻

5 Torr to about 760 Torr.

25. The process of claim 1 wherein the reduced pressure measures from about 10⁻

3 Torr to about 100 Torr.

26. The process of claim 1 wherein the reduced pressure is 760 Torr.

27. The process of claim 1 wherein the reaction temperature is maintained between 500°

C. and 1500°

C.

28. The process of claim 1 wherein the reaction temperature is maintained between 650°

C. and 1050°

C.

29. The process of claim 1 further comprising the steps of providing a material surface in the reactor and placing the catalytic particles on said material surface.

30. A process of claim 1 wherein the promoter gas is fed into the reactor prior to introduction of the carbon source gas in said reactor.

31. The process of claim 1 wherein the non-aligned carbon nanotubes are substantially comprised of linear unbranched tubules.

32. The process of claim 30 wherein the linear unbranched tubules have a hollow cylindrical morphology comprising at least one graphene layer.

33. The process of claim 30 wherein the linear unbranched tubules have a segmentally conical stacked array morphology comprising at least one graphene layer in each segment.

34. The process of claim 1 wherein the non-aligned carbon nanotubes are substantially comprised of branched tubules having at least one branching node along the tubule axis.

35. The process of claim 1 wherein the non-aligned carbon nanotubes are substantially branched tubules wherein a Y-junction is formed in at least one branching node.

37. The material of claim 36 wherein the non-aligned carbon nanotubes are substantially comprised of linear unbranched tubules.

38. The material of claim 36 wherein the linear unbranched tubules have a hollow cylindrical morphology comprising at least one graphene layer.

39. The material of claim 36 wherein the linear unbranched tubules have a segmentally conical stacked array morphology comprising at least one graphene layer in each segment.

40. The material of claim 36 wherein the non-aligned carbon nanotubes are substantially comprised of branched tubules having at least one branching node along the tubule axis.

41. The material of claim 36 wherein the non-aligned carbon nanotubes are substantially comprised of branched tubules wherein a Y-junction is formed in at least one branching node.

42. The material of claim 41 wherein adjacent branched tubules forming the Y-junction make an angle between 90°

to 240°

between each another.

43. The material of claim 41 wherein the adjacent branched tubules forming the Y-junction make an angle of about 120°

between one another.

36. A material composed of a plurality non-aligned carbon nanotubes comprising individual tubules having a cylindrical hollow single-walled or multi-walled structure.

44. A catalyst substrate material in the form of a mesoporous sol-gel particles comprising substantially uniform pores having coated thereon or impregnated within a metallic material.

45. The catalyst substrate material of claim 44 wherein the mesoporous sol-gel particles range from 10⁻

3 to 10³ microns.

46. The catalyst substrate material of claim 44 wherein the mesoporous sol-gel material is mesoporous silica, mesoporous alumina or mixtures thereof.

47. The catalyst substrate material of claim 44 wherein the metallic material is a transition metal, metal alloy or a combination thereof.

48. The catalyst substrate material of claim 44 wherein the metallic material is selected from the group consisting of iron, cobalt, nickel and combinations thereof.

49. The catalyst substrate material of claim 44 wherein the metallic material is iron or cobalt.

50. The catalyst substrate material of claim 44 wherein the catalyst particles additionally comprises at least one non-metallic material.

51. The catalyst substrate material of claim 49 wherein the non-metallic material is an organic or inorganic oxide, nitride, sulfide or carbide compound.

52. The catalyst substrate material of claim 50 wherein the metal oxide compound is selected from the group consisting of beryllium oxide, magnesium oxide, calcium oxide, strontium oxide and barium oxide.

53. The catalyst substrate material of claim 50 wherein the metal oxide is magnesium oxide.

54. The catalyst substrate material of claim 50 wherein the non-metallic material is an organo-metallic material.

55. The catalyst substrate material of claim 54 wherein the organo-metallic material is selected from the group consisting of ferrocene, nickelocene, cobaltocene and mixtures thereof.