Method for purification of as-produced single-wall carbon nanotubes

• US 6,936,233 B2
• Filed: 12/28/2001
• Issued: 08/30/2005
• Est. Priority Date: 03/07/1997
• Status: Expired due to Fees

• Current Assignee: Rice University
• Original Assignee: Rice University
• Inventors: Smalley, Richard E., Liu, Jie, Rinzler, Andrew G., Nikolaev, Pavel, Colbert, Daniel T., Thess, Andreas, Hafner, Jason H., Smith, Kenneth A., Guo, Ting, Dai, Hongjie
• Primary Examiner(s): HENDRICKSON, STUART L
• Application Number:
  US10/032,933
• Publication Number:
  US 20020127169A1
• Time in Patent Office: 1,341 Days
• Field of Search: 423/461, 423/447.1
• US Class Current: 423/447.1
• CPC Class Codes: B01J 19/081 employing particle radiation or gamma-radiation
• CPC Class Codes: B01J 19/087 employing electric or magnetic energy
• CPC Class Codes: B01J 19/10 employing sonic or ultrasonic vibrations
• CPC Class Codes: B01J 19/121 Coherent waves, e.g. laser beams lasers per se H01S3/00
• CPC Class Codes: B01J 19/126 Microwaves
• CPC Class Codes: B01J 19/129 Radiofrequency
• CPC Class Codes: B01J 21/185 Carbon nanotubes carbon nanotubes per se C01B32/15
• CPC Class Codes: B01J 2219/00078 Fingers
• CPC Class Codes: B01J 2219/0892 involving catalytically active material
• CPC Class Codes: B01J 23/74 Iron group metals
• CPC Class Codes: B01J 23/755 Nickel
• CPC Class Codes: B01J 23/8913 Cobalt and noble metals
• CPC Class Codes: B01J 37/0238 via the gaseous phase-sublimation
• CPC Class Codes: B01J 37/349 making use of flames, plasmas or lasers
• CPC Class Codes: B82B 3/00 Manufacture or treatment of nanostructures by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
• CPC Class Codes: C01B 2202/02 Single-walled nanotubes
• CPC Class Codes: C01B 32/156 After-treatment
• CPC Class Codes: C01B 32/162 characterised by catalysts
• CPC Class Codes: C01B 32/17 Purification
• CPC Class Codes: D01F 9/12 Carbon filaments; Apparatus specially adapted for the manufacture thereof
• 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: D21H 27/00 : Special paper not otherwise provided for, e.g. made by multi-step processes
• CPC Class Codes: G11B 9/1418 : Disposition or mounting of heads or record carriers G11B17/00 and G11B19/00 take precedence
• CPC Class Codes: G11B 9/1445 : switching at least one head in operating function; Controlling the relative spacing to keep the head operative, e.g. for allowing a tunnel current flow
• CPC Class Codes: G11B 9/1472 : characterised by the form
• CPC Class Codes: G11B 9/149 : characterised by the memorising material or structure
• CPC Class Codes: G11C 13/0014 : comprising cells based on organic memory material
• CPC Class Codes: G11C 13/0019 : comprising bio-molecules
• CPC Class Codes: G11C 13/025 : using fullerenes, e.g. C60, or nanotubes, e.g. carbon or silicon nanotubes
• CPC Class Codes: G11C 2213/16 : Memory cell being a nanotube, e.g. suspended nanotube
• CPC Class Codes: G11C 2213/71 : Three dimensional array
• CPC Class Codes: G11C 2213/81 : Array wherein the array conductors, e.g. word lines, bit lines, are made of nanowires
• CPC Class Codes: H01G 9/2059 : comprising an organic dye as the active light absorbing material, e.g. adsorbed on an electrode or dissolved in solution
• CPC Class Codes: H01L 31/0352 : characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
• CPC Class Codes: H01L 31/06 : characterised by potential barriers
• CPC Class Codes: H01L 31/18 : Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
• CPC Class Codes: H01M 10/0525 : Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 4/133 : Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/525 : of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: H01M 4/583 : Carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/587 : for inserting or intercalating light metals
• CPC Class Codes: H01M 4/625 : Carbon or graphite
• CPC Class Codes: Y02E 10/542 : Dye sensitized solar cells
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10S 977/70 : Nanostructure
• CPC Class Codes: Y10S 977/742 : Carbon nanotubes, CNTs
• CPC Class Codes: Y10S 977/745 : having a modified surface
• CPC Class Codes: Y10S 977/748 : Modified with atoms or molecules bonded to the surface
• CPC Class Codes: Y10S 977/75 : Single-walled
• CPC Class Codes: Y10S 977/753 : with polymeric or organic binder
• CPC Class Codes: Y10S 977/789 : in array format
• CPC Class Codes: Y10S 977/842 : for carbon nanotubes or fullerenes
• CPC Class Codes: Y10S 977/843 : Gas phase catalytic growth, i.e. chemical vapor deposition
• CPC Class Codes: Y10S 977/845 : Purification or separation of fullerenes or nanotubes
• CPC Class Codes: Y10S 977/847 : Surface modifications, e.g. functionalization, coating
• CPC Class Codes: Y10S 977/848 : Tube end modifications, e.g. capping, joining, splicing
• CPC Class Codes: Y10S 977/849 : with scanning probe
• CPC Class Codes: Y10S 977/882 : Assembling of separate components, e.g. by attaching
• CPC Class Codes: Y10S 977/948 : Energy storage/generating using nanostructure, e.g. fuel cell, battery
• CPC Class Codes: Y10T 428/24058 : including grain, strips, or filamentary elements in respective layers or components in angular relation
• CPC Class Codes: Y10T 428/2918 : including free carbon or carbide or therewith [not as steel]
• CPC Class Codes: Y10T 428/292 : In coating or impregnation
• CPC Class Codes: Y10T 428/30 : Self-sustaining carbon mass or layer with impregnant or other layer

Abstract

This invention relates generally to a single-wall carbon nanotube (SWNT) purification process and more particularly to a purification process that comprises heating the SWNT-containing felt under oxidizing conditions to remove the amorphous carbon deposits and other contaminating materials. In a preferred mode of this purification procedure, the felt is heated in an aqueous solution of an inorganic oxidant, such as nitric acid, a mixture of hydrogen peroxide and sulfuric acid, or a potassium permanganate. Preferably, SWNT-containing felts are refluxed in an aqueous solution of an oxidizing acid at a concentration high enough to etch away amorphous carbon deposits within a practical time frame, but not so high that the single-wall carbon nanotube material will be etched to a significant degree. When material having a high proportion of SWNT is purified, the preparation produced will be enriched in single-wall nanotubes, so that the SWNT are substantially free of other material.

Claims

1. A method for purifying a mixture comprising single-wall carbon nanotubes and amorphous carbon contaminate, said method comprising the steps of:

(a) heating said mixture under oxidizing conditions sufficient to remove the said amorphous carbon; and

(b) recovering a product comprising at least about 80% by weight of single-wall carbon nanotubes, wherein the product is washed with a solution comprising a surfactant.

2. The method of claim 1 wherein the surfactant is sodium dodecyl sulfate.

3. The method of claim 1 wherein the surfactant is a non-ionic surfactant.

4. A method for purifying a mixture comprising single-wall carbon nanotubes and amorphous carbon contaminate, said method comprising the steps of:

(a) heating said mixture under oxidizing conditions sufficient to remove the said amorphous carbon; and

(b) recovering a product comprising at least about 80% by weight of single-wall carbon nanotubes.

5. The method of claim 4 wherein said oxidizing conditions comprise an aqueous solution of an inorganic oxidant.

6. The method of claim 5 wherein said inorganic oxidant is selected from the group consisting of nitric acid, a mixture of sulfuric acid and hydrogen peroxide, potassium permanganate and mixtures thereof.

7. The method of claim 5 wherein said aqueous solution is heated to reflux.

8. The method of claim 5 additionally comprising the step of subjecting the oxidized product of step (b) to a saponification treatment.

9. The method of claim 8 wherein said saponification treatment comprises contacting said product with a basic solution.

10. The method of a claim 9 wherein said basic solution comprises sodium hydroxide.

11. The method of claim 9 additionally comprising the step of neutralizing the saponified product with an acid.

12. The method of claim 11 wherein said acid is hydrochloric acid.

13. The method of claim 11 additionally comprising the step of recovering a solid product from the saponified, neutralized product.

14. The method of claim 13 wherein said product is recovered by a method selected from the group consisting of filtration, settling by gravity, chemical flocculators, and liquid cycloning.

15. The method of claim 13 wherein said solid product is a paper-like two-dimensional product.

16. The method of claim 15 additionally comprising the step of drying the product.

17. The method of claim 16 wherein said product is dried at about 850°

C. in a hydrogen gas atmosphere.

18. The method of claim 4 wherein said product comprises at least about 90% by weight of single-wall carbon nanotubes.

19. The method of claim 4 wherein said product comprises at least about 95% by weight of single-wall carbon nanotubes.

20. The method of claim 4 wherein said product comprises at least about 99% by weight of single-wall carbon nanotubes.

21. A method for purifying a mixture comprising single-wall carbon nanotubes and amorphous carbon contaminate, said method comprising the steps of:

(a) heating said mixture under oxidizing conditions; and

(b) recovering a product comprising at least about 80% by weight of single-wall carbon nanotubes, wherein the product comprises fullerene torroids.