Electric arc process for making fullerenes

• US 5,227,038 A
• Filed: 10/04/1991
• Issued: 07/13/1993
• Est. Priority Date: 10/04/1991
• Status: Expired due to Term

• Current Assignee: Rice University
• Original Assignee: Rice University
• Inventors: Haufler, Robert E., Smalley, Richard E.
• Primary Examiner(s): Lewis, Michael L.
• Assistant Examiner(s): STRAUB, GARY P
• Application Number:
  US07/771,741
• Time in Patent Office: 648 Days
• Field of Search: 423/446, 423/445, 423/445 B, 423/460, 156/DIG. 68, 204/172, 204/173
• US Class Current: 204/173
• 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 32/15 Nano-sized carbon materials
• CPC Class Codes: C01B 32/154 Preparation
• CPC Class Codes: Y10S 977/742 Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/843 Gas phase catalytic growth, i.e. chemical vapor deposition
• CPC Class Codes: Y10S 977/844 Growth by vaporization or dissociation of carbon source using a high-energy heat source, e.g. electric arc, laser, plasma, e-beam
• CPC Class Codes: Y10S 977/901 having step or means utilizing electromagnetic property, e.g. optical, x-ray, electron beamm

Abstract

This invention provides a method of generating fullerenes by vaporizing carbon with the heat from an electrical arc and then condensing a soot from which fullerenes may be recovered.

Claims

1. A process for making fullerenes comprising:

(a) providing a carbon vapor generation zone which comprises a first electrode and a second electrode,

(b) maintaining the carbon vapor generation zone in an atmosphere consisting essentially of an atmosphere selected to form fullerene molecules,

(c) applying sufficient electrical voltage to the first electrode to maintain an electrical arc between the first electrode and the second electrode,

(d) providing a carbon source in close proximity to the electrical arc, so that the carbon source is heated by the electrical arc to form a carbon vapor,

(e) passing the carbon vapor to a fullerene condensing zone where the carbon vapor is condensed into a solid carbon soot, and

(f) recovering fullerenes from the carbon soot.

2. A process in accordance with claim 1 wherein either the first electrode or the second electrode comprises carbon.

3. A process in accordance with claim 1 wherein the first electrode and the second electrode are both comprised of carbon.

4. A process in accordance with claim 3 wherein the carbon vapor generation zone and the fullerene condensing zone are maintained in an atmosphere consisting essentially of an inert gas at a pressure of 5 to 2000 Torr.

5. A process in accordance with claim 4 wherein the inert gas is helium and the pressure of the inert gas ranges from 50 to 500 Torr.

6. A process in accordance with claim 5 wherein the carbon vapor is passed through a fullerene growth and annealing zone maintained at a temperature of 1000 to 2000°

C. before being passed to the fullerene condensing zone.

7. A process in accordance with claim 6 wherein the electrical power supplied to the first electrode ranges from 10 to 500 amps at 10 to 50 volts rms.

8. A process in accordance with claim 7 wherein the first electrode and the second electrode are maintained apart, to produce an arc gap of between 0.01 and 10 mm.

9. A process in accordance with claim 4 wherein the inert gas passes through the carbon vapor generation zone, through the fullerene condensing zone, is withdrawn from the fullerene condensing zone and recirculated back to the carbon vapor generation zone.

10. A process in accordance with claim 1 wherein providing a carbon source in close proximity to the electrical arc is accomplished by passing graphite dust around or through the electrical arc.

11. A process in accordance with claim 10 wherein the graphite dust is carried to the electrical arc by an inert gas.

12. A process in accordance with claim 11 wherein the inert gas is helium, and the carbon vapor generation zone and fullerene condensing zone are maintained in an atmosphere consisting essentially of helium at a pressure of 10 to 700 Torr.

13. A process in accordance with claim 12 further comprising a fullerene growth and annealing zone maintained at a temperature of 1000°

to 2000°

C., wherein the carbon vapor is passed through the fullerene growth and annealing zone and thereafter to the fullerene condensing zone.

14. A process in accordance with claim 11 wherein the inert gas passes through the carbon vapor generation zone, through a fullerene growth and annealing zone, through the fullerene condensing zone, is withdrawn from the fullerene condensing zone and recirculated back to the carbon vapor generation zone.

15. A process in accordance with claim 14 wherein carbon soot is separated from the inert gas before the inert gas is recalculated back to the carbon vapor generation zone.

16. A process for making fullerenes comprising vaporizing carbon with a plasma in an atmosphere consisting essentially of an atmosphere that promotes fullerene growth and formation thereby forming fullerenes and recovering said fullerenes.

17. A process in accordance with claim 16 where in the plasma is maintained as an electrical arc between two electrodes.

18. A process in accordance with claim 17 wherein an inert gas circulates and carries vaporized carbon away from the plasma into a zone where fullerene growth and formation occurs.

19. A process in accordance with claim 18 wherein the inert gas is moved from the zone where fullerene growth and formation occurs and is recirculated back to the plasma.