US5641466A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of purifying carbon nanotubes
Assignee: NEC Corp
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Filing: 1994-06-02
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Granted: 1997-06-24
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Expires: 2014-06-02
Abstract
Abstract A mixture of carbon nanotubes and impurity carbon materials, which include carbon nanoparticles and may possibly include amorphous carbon, is purified into carbon nanotubes of high purity by utilizing a significant difference in oxidizability between the nanotubes and the nanoparticles. The mixture is pulverized and heated in the presence of an oxidizing agent at a temperature in the range from 600° to 1000° C. until the impurity carbon materials are oxidized and dissipated into gas phase. The nanotubes remain almost unoxidized except for loss of some lengths from the tube tips. It is suitable to perform the heating in air or oxygen.
Inventors
- 👤 Thomas Ebbesen
- 👤 Pulickel M. Ajayan
- 👤 Hidefumi Hiura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:16
CPC Classifications
D; D01; D01F; D01F9/00; D01F9/08; D01F9/12; B; B82; B82Y; B82Y30/00; B82Y40/00; C; C01; C01B; C01B32/00; C01B32/15; C01B32/158; C01B32/168; C01B32/17; C01B2202/00; C01B2202/20; C01B2202/36; Y; Y10; Y10S; Y10S977/00; Y10S977/70; Y10S977/734; Y10S977/742; Y10S977/84; Y10S977/842; Y10S977/845; Y10S977/90
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
103 words
A method of purifying a mixture of carbon nanotubes and impurity carbon materials which include polyhedral carbon nanoparticles which are smaller than about 100 nanometers in diameter, into carbon nanotubes of high purity, comprising the steps of: finely dividing said mixture into a powder form; and heating said mixture in the powder form at a temperature in the range from 600° C. to 1000° C. in the presence of air or oxygen gas to selectively oxidize said impurity carbon materials until said impurity carbon materials are oxidized and dissipated into gas phase resulting in carbon nanotubes that are essentially free of carbon nanoparticles.
Claim 2
Independent Claim
103 words
A method of purifying a mixture of carbon nanotubes and impurity carbon materials which include polyhedral carbon nanoparticles which are smaller than about 100 nanometers in diameter, into carbon nanotubes of high purity, comprising the steps of: finely dividing said mixture into a powder form; and heating said mixture in the powder form at a temperature in the range from 600° C. to 1000° C. in the presence of air or oxygen gas to selectively oxidize said impurity carbon materials until said impurity carbon materials are oxidized and dissipated into gas phase resulting in carbon nanotubes that are essentially free of carbon nanoparticles.
Claim 3
Independent Claim
99 words
A method of purifying a mixture of carbon nanotubes and impurity carbon materials which include polyhedral carbon nanoparticles which are smaller than about 100 nanometers in diameter, into carbon nanotubes of high purity, comprising the steps of: finely dividing said mixture into a powder form; and heating said mixture in the powder form in an oxidizing gas to selectively oxidize said impurity carbon materials at a temperature in the range from 600° C. to 1000° C. until said impurity carbon materials are oxidized and dissipated into gas phase resulting in carbon nanotubes that are essentially free of carbon nanoparticles.
Claim 4
Independent Claim
99 words
A method of purifying a mixture of carbon nanotubes and impurity carbon materials which include polyhedral carbon nanoparticles which are smaller than about 100 nanometers in diameter, into carbon nanotubes of high purity, comprising the steps of: finely dividing said mixture into a powder form; and heating said mixture in the powder form in an oxidizing gas to selectively oxidize said impurity carbon materials at a temperature in the range from 600° C. to 1000° C. until said impurity carbon materials are oxidized and dissipated into gas phase resulting in carbon nanotubes that are essentially free of carbon nanoparticles.
Claim 5
Dependent Claim
12 words
A method according to claim 2, wherein said oxidizing gas is air.
Claim 6
Dependent Claim
15 words
A method according to claim 3, wherein said temperature is not lower than 700° C.
Claim 7
Dependent Claim
12 words
A method according to claim 2, wherein said oxidizing gas is oxygen.
Claim 8
Dependent Claim
12 words
A method according to claim 2, wherein said oxidizing gas is steam.
Claim 9
Dependent Claim
13 words
A method according to claim 2, wherein said oxidizing gas is carbon dioxide.
References Cited (Backward Citations)
US5346683A
Cited
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