# US 7,410,629 B2 · Method of preparation for carbon nanotube material

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- Number: US 7,410,629 B2
- Document ID: US7410629B2
- Status: Granted
- Kind: B2
- Application number: 11/004,242
- Filed: 2004-12-03
- Published: 2006-03-23
- Granted: 2008-08-12
- Earliest claimed: 2004-06-15
- Assignees: Changchun Institute of Applied Chemistry Chinese Academy of Science
- Inventors: Tao Tang; Xuecheng Chen; Xiaoyu Meng
- Web page: https://patentgrep.com/patent/US7410629B2

## CPC

- C01B 32/162: characterised by catalysts
- B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites
- B82Y 40/00: Manufacture or treatment of nanostructures
- Y10S 977/842: for carbon nanotubes or fullerenes
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

The present invention provides a method for preparing a carbon nanotube material. In the present invention, a mixture of polyolefin and modified montmorillonite is used as the carbon source. Under the action of a catalyst, a carbon nanotube is synthesized in air. The present invention can address the problem of “white pollution” caused by waste plastics, such as waste polyolefin polymers.

## Claims

### Claim 1

A method for preparing a carbon nanotube material, comprising the steps of:
(a) preparing a modified montmorillonite by an ion exchange reaction comprising the substeps of:
i) acidifying an alkylamine with equal mole of a concentrated HCl;
ii) mixing the resulting acidified alkylamine with a montmorillonite dispersion in 1:1˜2 volume ratio of the acidified alkylamine to the montmorillonite dispersion; and
iii) precipitating, filtering and pulverizing to obtain a modified montmorillonite;
(b) preparing a catalyst by a hydrogenation reduction method, comprising the substeps of:
i) mixing an aqueous solution of nickel nitrate and an alumina-silica hybrid in a weight ratio of 35-45 parts of nickel to 55-65 parts of alumina-silica hydrid, wherein the alumina-silica hydrid contains 10 wt % of alumina and has a particle size of 10-30 μm;
ii) drying and calcining the resulting product; and
iii) reducing the product with a reducing gas containing hydrogen to produce a nickel-supported catalyst;
(c) preparing a polyolefin mixture of a polyolefin, the modified montmorillonite prepared in step a) and the catalyst prepared in step b) in a mixer in the weight ratio of 75˜97.5:0˜20:0˜5 provided that the amounts of the modified montmorillonite and the catalyst are not both 0;
(d) preparing and purifying a nanotube, comprising the substeps of:
i) placing the polyolefin mixture obtained in step (c) in a crucible and heating the temperature inside crucible up to 550° C.˜650° C., wherein the heating time begins from the burning of the polymer and ends when no flame can be observed and cooling the polyolefin mixture to obtain a mixture of carbon nanotube, nickel catalyst and montmorillonite;
ii) adding a hydrofluoric acid with a concentration of 20-50% to the mixture, mixing, and separating to obtain a carbon powder; and
iii) adding a mixture of a concentrated sulfuric acid and a concentrated nitric acid, refluxing, and separating to obtain a purified carbon nanotube.

### Claim 2 (depends on 1)

The process acoording to claim 1, wherein the montmorillonite is a micrometer grade montmorillonite.

### Claim 3 (depends on 1)

The process according to claim 1, wherein the catalyst is a catalyst containing a micrometer grade alumina-silica hybrid as a support on which nickel particles are loaded.

### Claim 4 (depends on 1)

The process according to claim 1, wherein the step (c) further comprising the substeps of: premixing the polyolefin and the modified montmorillonite; feeding the mixture through a main feed port into an extruder where the mixture is melted and mixed to give a parent stock; and feeding the catalyst through the second feed port and further melting and mixing, wherein the temperatures at different sections of the extruder were in the range of 160°˜200° C. and the screw revolution velocity of the extruder was 200˜300 rpm.

### Claim 5 (depends on 1)

The process according to claim 1, wherein the polyolefin is at least one selected from a group consisting of polypropylene, polyethylene, ethylene-propylene copolymer and polystyrene.