Gas-phase process for purifying single-wall carbon nanotubes and compositions thereof
First Claim
1. A method for purifying single-wall carbon nanotubes comprising the steps of:
- (a) oxidizing a single-wall carbon nanotube material in an oxidizing gaseous atmosphere at a temperature between about 200°
C. and about 500°
C. and at a pressure between about 0.01 and about 100 atmospheres, wherein the oxidizing gaseous atmosphere comprises a gas selected from the group consisting of oxygen, carbon dioxide, and mixtures thereof; and
(b) treating the single-wall carbon nanotube material with a halogen-containing gas subsequent to the step of oxidizing.
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Abstract
The present invention relates to an all gas-phase process for the purification of single-wall carbon nanotubes and the purified single-wall carbon nanotube material. Known methods of single-wall carbon nanotube production result in a single-wall carbon nanotube product that contains single-wall carbon nanotubes in addition to impurities including residual metal catalyst particles and amounts of small amorphous carbon sheets that surround the catalyst particles and appear on the sides of the single-wall carbon nanotubes and “ropes” of single-wall carbon nanotubes. The purification process removes the extraneous carbon as well as metal-containing residual catalyst particles. The process comprises oxidation of the single-wall carbon nanotube material, reduction and reaction of a halogen-containing gas with the metal-containing species. The oxidation step may be done dry or in the presence of water vapor. The present invention provides a scalable means for producing high-purity single-wall carbon nanotube material.
54 Citations
55 Claims
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1. A method for purifying single-wall carbon nanotubes comprising the steps of:
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(a) oxidizing a single-wall carbon nanotube material in an oxidizing gaseous atmosphere at a temperature between about 200°
C. and about 500°
C. and at a pressure between about 0.01 and about 100 atmospheres, wherein the oxidizing gaseous atmosphere comprises a gas selected from the group consisting of oxygen, carbon dioxide, and mixtures thereof; and(b) treating the single-wall carbon nanotube material with a halogen-containing gas subsequent to the step of oxidizing. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 18, 19, 20, 21, 22, 23)
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14. A method for purifying single-wall carbon nanotubes comprising:
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(a) oxidizing a single-wall carbon nanotube material in an oxidizing gaseous atmosphere; (b) treating the single-wall carbon nanotube material with a halogen-containing gas; and (c) annealing the single-wall carbon nanotube material, wherein the annealing step is performed in a vacuum.
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16. A method for purifying single-wall carbon nanotubes comprising:
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(a) oxidizing a single-wall carbon nanotube material in an oxidizing gaseous atmosphere; (b) treating the single-wall carbon nanotube material with a halogen-containing gas; and (c) annealing the single-wall carbon nanotube material, wherein the annealing step is performed with an annealing gas comprising a gas selected from the group consisting of carbon dioxide, inert gases, nitrogen, and combinations thereof and wherein the annealing gas further comprises water vapor. - View Dependent Claims (17)
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24. A method for purifying single-wall carbon nanotubes comprising the steps of:
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(a) oxidizing a single-wall carbon nanotube material comprising single-wall carbon nanotubes, amorphous carbon, and a metallic impurity in an oxidizing gaseous atmosphere, wherein the oxidizing gaseous atmosphere comprises a gas selected from the group consisting of oxygen, carbon dioxide and mixtures thereof; (b) reducing the single-wall carbon nanotube material with a reducing gas comprising hydrogen subsequent to the step of oxidizing; and (c) treating the single-wall carbon nanotube material with a halogen-containing gas subsequent to the step of reducing. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
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54. A method for purifying carbon nanotubes comprising the steps of:
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(a) oxidizing a carbon nanotube material in an oxidizing gaseous at a temperature between about 200°
C. and about 500°
C. and at a pressure between about 0.01 and about 100 atmospheres, wherein the oxidizing gaseous atmosphere comprises a gas selected from the group consisting of oxygen, carbon dioxide and mixtures thereof; and(b) treating the carbon nanotube material with a halogen-containing gas subsequent to the step of oxidizing.
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55. A method for purifying carbon nanotubes comprising the steps of:
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(a) oxidizing a carbon nanotube material comprising carbon nanotubes, amorphous carbon, and a metallic impurity in an oxidizing gaseous atmosphere, wherein the oxidizing gaseous atmosphere comprises a gas selected from the group consisting of oxygen, carbon dioxide and mixtures thereof; (b) reducing the carbon nanotube material with a reducing gas comprising hydrogen subsequent to the step of oxidizing; and (c) treating the carbon nanotube material with a halogen-containing gas subsequent to the step of reducing.
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Specification