Synthesis of carbon nanotubes by making use of microwave plasma torch

• US 20050163696A1
• Filed: 01/28/2004
• Published: 07/28/2005
• Est. Priority Date: 01/28/2004
• Status: Abandoned Application

• Current Assignee: Han S. Uhm
• Original Assignee: Han S. Uhm
• Inventors: Hong, Yong C., Uhm, Han Sup
• Application Number:
  US10/765,171
• Publication Number:
  US 20050163696A1
• Time in Patent Office: Days
• US Class Current: 423/445.B
• CPC Class Codes: B01J 19/088 giving rise to electric discharges for heating purposes H05B7/00; for the production of ozone C01B13/11, H01T19/00
• CPC Class Codes: B01J 19/126 Microwaves
• CPC Class Codes: B01J 19/26 Nozzle-type reactors, i.e. the distribution of the initial reactants within the reactor is effected by their introduction or injection through nozzles
• CPC Class Codes: B01J 2219/0809 employing two or more electrodes
• CPC Class Codes: B01J 2219/083 cylindrical
• CPC Class Codes: B01J 2219/0841 Metal
• CPC Class Codes: B01J 2219/0869 Feeding or evacuating the reactor
• CPC Class Codes: B01J 2219/0871 Heating or cooling of the reactor
• CPC Class Codes: B01J 2219/0883 Gas-gas
• CPC Class Codes: B01J 2219/0892 involving catalytically active material
• CPC Class Codes: B01J 2219/0898 Hot plasma
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• 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 2202/02 Single-walled nanotubes
• CPC Class Codes: C01B 2202/34 Length
• CPC Class Codes: C01B 2202/36 Diameter
• CPC Class Codes: C01B 32/162 characterised by catalysts
• CPC Class Codes: H05B 6/806 for laboratory use
• CPC Class Codes: H05H 1/30 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/28 takes precedence

Abstract

The present invention relates to a synthesis method of carbon nanotubes, and more particularly to an apparatus for a mass synthesis of carbon nanotubes in gas phase using an atmospheric-pressure microwave plasma torch. The method and apparatus is described for the continuous production of carbon nanotubes by making use of a microwave plasma torch operated at a frequency of 2.45 GHz, by introducing a transition metal catalyst precursor and a carbon containing gas into the microwave plasma torch to produce atomized catalyst metal and to decompose the carbon containing gas, by passing the resulting gaseous mixtures through a furnace, and by quenching rapidly and collecting the products so formed at the exit of the furnace. The resultant products are the carbon nanotubes.

Claims

1. An apparatus for continuous and mass synthesis of carbon nanotubes, said apparatus comprising:

(a) a discharge tube equipped with a microwave radiation generator for forming a microwave plasma torch with an ignition device and a multi-port gas injection system for injecting a carrier gas containing metal catalyst precursor vaporized and a carbon containing gas for forming carbon nanotubes;

(b) a furnace for passing the resulting gases mixture

(c) a collector system for quenching and collecting carbon nanotubes.

2. In the apparatus according to claim 1, wherein the said microwave plasma torch is capable of operating at 2.45 GHz and at power ranges of 0.1 to 6 kW with the assistance of auxiliary ignition systems.

3. In the apparatus according to claim 1, wherein the furnace is horizontally connected to the microwave plasma torch.

4. In the apparatus according to claim 1, wherein the furnace is 12˜

22 inch long.

5. In the apparatus according to claim 1, wherein said gas injection system comprising a plurality of swirl gas inlets.

6. In the apparatus according to claim 1, wherein the furnace is capable of operating at temperature in the range of 600˜

1200°

C.

7. A process for continuous and mass synthesis of carbon nanotubes by introduction of microwave energy into an electric field to which carbon nanotube forming material is exposed, comprising:

(a) injecting a swirl gas as plasma or diluent gas into a dielectric discharge tube;

(b) creating an intense electric field in the swirl gas in the dielectric discharge tube by an incident and reflected electromagnetic wave generated by a magnetron and propagated through a tapered rectangular waveguide;

(c) forming an atmospheric-pressure plasma torch flame with the help of an ignition system in said electric field;

(d) introducing a vaporized metal catalyst or metal catalyst precursor and a carbon-containing gas into the center of the plasma torch flame;

(e) atomizing and ionizing carbon nanotube forming materials by molecular breakdowns and hot gases, and simultaneously mixing them with the swirl gas;

(f) passing the resulting gaseous mixtures through a furnace; and

(g) quenching and collecting carbon nanotubes in a collector system.

8. In the process according to claim 7, wherein the carbon nanotubes grow at a temperature of 600˜

1200°

C.

9. In the process according to claim 7, wherein the carbon nanotubes grow at one atmosphere.

10. In the process according to claim 7, wherein the transition metal catalyst is atomized at a pressure of 1 atmosphere.

11. In the process according to claim 7, wherein the carbon-containing gas is mixed and injected with the swirl gas.

12. In the process according to claim 7, wherein the metal catalyst or metal catalyst precursor is injected through one auxiliary inlet port or a plurality of inlet ports and is atomized at a temperature of 600˜

1200°

C.