Preparation method of single-walled carbon nanotube
By burning the alloy tube into carbon materials under high temperature and oxygen-rich conditions, the problems of complex process, high cost and serious environmental pollution in the prior art are solved, and a continuous preparation method of simple process, low cost and environmentally friendly is realized.
Patent Information
- Application Number
- CN202510187981.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-20
- Publication Date
- 2025-03-28
AI Technical Summary
In the prior art, when preparing single-wall carbon nanotubes, the process is complex, the cost is high, the environmental pollution is serious, and it is difficult to achieve continuous preparation.
By passing the preheated oxygen-containing combustion-assisted gas into the alloy tube and pushing the other end of the alloy tube into the carbon material to burn, the heat generated by the combustion of the alloy tube under high-temperature oxygen-rich conditions is used to form a single-walled carbon nanotube.
A single-wall carbon nanotube preparation method with simple process, low cost and low environmental pollution is realized, and continuous preparation can be carried out.
Smart Images
Figure CN119706811A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for preparing single-walled carbon nanotubes, and belongs to the technical field of new materials. Background Art
[0002] In 1991, Japanese scientist Iijima discovered a needle-shaped tubular carbon nanotube. Carbon nanotubes, also known as buckytubes, are one-dimensional quantum materials with a special structure (radial dimensions are nanometers, axial dimensions are micrometers, and both ends of the tube are basically sealed). It is mainly composed of several to dozens of layers of coaxial circular tubes composed of carbon atoms arranged in a hexagonal pattern. The distance between layers is fixed, about 0.34 nm, and the diameter is generally 2~20nm.
[0003] Carbon nanotubes have similar properties to fullerene molecules (there are five-membered carbon rings on their end faces). Due to their unique electronic structure and physical and chemical properties, their application in various fields has attracted widespread attention from scientists from all over the world. Carbon nanotubes have a large surface area ratio (length / diameter) and strong mechanical properties (5 to 10 times higher than graphite). They may become another new type of carbon fiber material after polyacrylonitrile-based carbon fibers and asphalt-based carbon fibers.
[0004] The matrix of carbon nanotube composite materials can be made of resin, carbon, metal and inorganic materials. Plastics reinforced with carbon nanotube materials not only have excellent mechanical properties, but also have fatigue resistance, creep resistance, and stable material dimensions. Due to the small friction coefficient, they have good sliding properties and better vibration attenuation than metals. In addition, they also have the advantages of conductivity, corrosion resistance, shielding of radio waves and good X-ray transmittance. Since the walls of carbon nanotubes can be dissolved by certain chemical reactions, they can be used as molds that are easy to handle. Carbon nanotubes can also be used as carriers for other metal and metal oxide catalysts to maximize the efficiency of the catalyst.
[0005] In order to test the electronic structure and mechanical strength of carbon nanotubes, people hope to obtain carbon nanotubes with better morphology, longer length, thinner thickness and fewer nested layers. Although carbon nanotubes synthesized by arc method are usually multi-layered, when performing relevant calculations on carbon nanotubes, people are most concerned about single-layer carbon nanotubes.
[0006] In 1993, Iijima of NEC Corporation in Japan and Bethune research group of IBM Corporation in the United States discovered the synthesis of single-layer carbon nanotubes almost at the same time. Iijima filled a conventional arc discharge reactor with methane and argon with a total pressure of 1.33*104 Pa, replaced part of the cathode carbon electrode with iron, and evaporated iron and carbon at the same time to obtain single-layer carbon nanotubes. Bethune et al. filled the anode carbon rod with metal cobalt powder in the process of preparing carbon nanotubes by arc discharge, and after evaporating it in a helium atmosphere, they found single-layer carbon nanotubes with a diameter of 1~2nm in the rubber-like blocks generated in the reactor. Saito of Mie University in Japan filled the anode rod with nickel or rare earth elements and synthesized the smallest carbon nanotubes reported so far. Their average diameter is about 1nm and the minimum diameter is 0.7nm.
[0007] The current methods for preparing single-walled carbon nanotubes mainly include arc discharge, laser ablation and chemical vapor deposition.
[0008] Among them, arc discharge method and laser ablation method are difficult to achieve and control the appropriate growth rate of single-walled carbon nanotubes and the patterning on a specific substrate. The arc discharge method requires the re-preparation of carbon electrodes, which are made of carbonaceous materials as raw materials, and add appropriate amounts of binders and catalysts to make high-temperature resistant carbon material products. Binders include asphalt, tar and anthracene oil binders. These binders are seriously polluted during the preparation of carbon electrodes. In addition, the preparation of carbon nanotubes by the arc method is discontinuous. After the carbon electrode is consumed, the carbon electrode needs to be replaced intermittently, usually in a protective atmosphere environment (generally using helium protection), which is not easy to expand production.
[0009] Chemical vapor deposition systems and precursor gases are expensive, especially for high-temperature processes. The high cost of equipment, including vacuum pumps, gas flow controllers, and high-temperature furnaces, can be a significant barrier for some applications. Summary of the invention
[0010] In view of the problems existing in the above-mentioned prior art, the object of the present invention is to provide a method for preparing single-walled carbon nanotubes, which has simple process, low cost, less environmental pollution, and can be used for continuous preparation of single-walled carbon nanotubes.
[0011] In order to achieve the above-mentioned purpose, the first aspect of the present invention is to provide a method for preparing single-walled carbon nanotubes, which method comprises: continuously introducing preheated oxygen-containing combustion-supporting gas into the alloy tube from one end of the alloy tube, and at the same time continuously pushing the other end of the alloy tube into the carbon material for combustion, and collecting the carbon black product produced by the combustion of the alloy tube in the carbon material.
[0012] The innovation of the present invention lies in that a high-temperature combustion-supporting gas passes through the alloy tube, and the other end of the alloy tube is placed in a carbon material environment. After the high-temperature combustion-supporting oxygen-containing gas ignites the carbon material, the alloy tube placed in the carbon material environment begins to burn under conditions of high temperature and oxygen content. As the alloy tube burns, the alloy tube is continuously fed into excess carbon material. When the alloy tube burns in the carbon material environment, the carbon black products containing metal carbides scattered by the alloy tube in the carbon material are collected. The heat generated by the combustion of the alloy tube under high-temperature oxygen-rich conditions can have a theoretical combustion temperature of more than 3000°C. On the one hand, the metal catalyst in the alloy tube is gasified, and on the other hand, the carbon material is oxidized into carbon monoxide. The carbon monoxide precipitates carbon in the high-temperature environment, and a small amount of carbon is also gasified. These carbons form carbon nanotubes in the high-temperature environment of the catalyst, thus obtaining single-walled carbon nanotubes.
[0013] It should be noted that the present invention has no special requirements on the pushing speed of continuously pushing the other end of the alloy tube into the carbon material, as long as it is ensured that the alloy tube is placed in the carbon and burns.
[0014] In the preferred embodiment, the oxygen-containing combustion-supporting gas contains no less than 25% oxygen by volume, its flow rate is 6-20 L / min, and the preheating temperature is 1000-1200°C.
[0015] In a preferred embodiment, the carbon material is a carbon block. When the carbon material is a carbon block, it is not easy to be blown away and can better form single-walled carbon nanotubes.
[0016] In a preferred embodiment, the carbon material is selected from at least one of metallurgical coke, graphite carbon bricks and semi-graphite carbon bricks.
[0017] In a preferred embodiment, the alloy tube contains at least one metal element selected from the group consisting of Fe, Co, Ni and rare earth metals.
[0018] In a more preferred embodiment, the alloy tube is selected from at least one of a cobalt alloy tube, a nickel-cobalt alloy, an iron-cobalt-nickel alloy, a carbon steel tube and a nickel alloy tube.
[0019] In a preferred embodiment, the wall thickness of the alloy tube is no more than 2.5 mm.
[0020] In a more preferred embodiment, the wall thickness of the alloy tube is 0.5-2 mm. The inventors have found that if the wall of the alloy tube is too thin, the yield of carbon nanotubes will be reduced, and if the wall of the alloy tube is too thick, the combustion temperature may be too low to meet the generation conditions of carbon nanotubes.
[0021] In a further preferred embodiment, the outer diameter of the alloy tube is 6-10 mm.
[0022] In a preferred embodiment, the method further comprises washing the collected carbon black product with nitric acid solution, sodium hydroxide solution, hydrofluoric acid solution and water in sequence, and obtaining single-walled carbon nanotubes after drying. The washing is mainly to remove metal and non-metal impurities in the carbon black product, so as to obtain single-walled carbon nanotubes with higher purity.
[0023] In a preferred embodiment, the concentration of the nitric acid solution is 10-15wt%, the concentration of the sodium hydroxide solution is 40-50wt%, and the concentration of the hydrofluoric acid solution is 10-15wt%.
[0024] It should be noted that the present invention has no special requirements for the cleaning and drying conditions, and any conditions known in the art may be used.
[0025] Compared with the prior art, the present invention has at least the following advantages:
[0026] The method for preparing single-walled carbon nanotubes provided by the invention has simple process, low cost and less environmental pollution, and can be used for continuous preparation of single-walled carbon nanotubes. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 This is a high-resolution electron microscope test image of the single-walled carbon nanotubes prepared in Example 1;
[0028] Figure 2 This is a high-resolution electron microscope test image of the single-walled carbon nanotubes prepared in Example 2;
[0029] Figure 3 This is a high-resolution electron microscope test image of the single-walled carbon nanotubes prepared in Example 3;
[0030] Figure 4 This is a high-resolution electron microscope test image of the single-walled carbon nanotubes prepared in Example 3. DETAILED DESCRIPTION
[0031] The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.
[0032] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the following specific embodiments. Obviously, the embodiments described below are only a part of the embodiments, and all other embodiments obtained by professionals in this field without creative work still belong to the protection scope of the present invention.
[0033] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.
[0034] Example 1
[0035] A combustion-supporting gas with an oxygen content of 25% (volume fraction) is heated to 1150°C, and the high-temperature combustion-supporting gas is sent from one end of the alloy tube to a N02200 pure nickel alloy tube with an outer diameter of 6mm and a wall thickness of 0.6mm. The combustion-supporting gas flow rate is 8L / min. The other end of the alloy tube is placed in a carbon environment, and the carbon burns with the combustion-supporting gas. The outlet end of the alloy tube begins to ignite and burn under conditions of high temperature and high oxygen content. As the alloy tube burns, the alloy tube is continuously fed into excess carbon (graphite carbon bricks). When the alloy tube burns in the carbon environment, the scattered carbon black products containing metal carbides generated by the combustion of the alloy tube in the carbon are collected, and the collected scattered carbon black products are soaked and cleaned with 15wt% dilute nitric acid, 40wt% sodium hydroxide solution, and 15wt% hydrofluoric acid solution, respectively, and finally washed with pure water and dried to obtain single-walled carbon nanotubes.
[0036] The single-walled carbon nanotubes prepared in the above example were tested using a high-resolution electron microscope. The test results are shown in Figure 1 ,from Figure 1 It can be seen that single-walled carbon nanotubes were prepared in this example.
[0037] Example 2
[0038] This example is carried out in a similar manner to that of Example 1, except that the flow rate of the combustion-supporting gas is adjusted to 12 L / min to obtain single-walled carbon nanotubes.
[0039] The single-walled carbon nanotubes prepared in the above example were tested using a high-resolution electron microscope. The test results are shown in Figure 2 ,from Figure 2 It can be seen that single-walled carbon nanotubes were prepared in this example.
[0040] Example 3
[0041] This example is carried out in a similar manner to that of Example 1, except that the alloy tube is changed to a Q235 carbon steel tube, and the wall thickness and inner diameter of the alloy tube remain unchanged, thereby obtaining single-walled carbon nanotubes.
[0042] The single-walled carbon nanotubes prepared in the above example were tested using a high-resolution electron microscope. The test results are shown in Figure 3 ,from Figure 3 It can be seen that single-walled carbon nanotubes were prepared in this example.
[0043] Example 4
[0044] This example is carried out in a similar manner to that of Example 1, except that the alloy tube is replaced with a N02200 pure nickel alloy tube having an outer diameter of 6 mm and a wall thickness of 2 mm, thereby obtaining single-walled carbon nanotubes.
[0045] The single-walled carbon nanotubes prepared in the above example were tested using a high-resolution electron microscope. The test results are shown in Figure 4 ,from Figure 4 It can be seen that single-walled carbon nanotubes were prepared in this example.
[0046] Comparative Example 1
[0047] A combustion-supporting gas with an oxygen content of 25% (volume fraction) is heated to 1150°C with a flow rate of 8 L / min. Nickel powder is placed in a carbon environment, and carbon (the same as in Example 1) is burned together with the combustion-supporting gas and nickel powder. The scattered carbon black products containing metal carbides produced by the combustion in the carbon are collected, and the collected scattered carbon black products are soaked and cleaned with 15wt% dilute nitric acid and 15wt% hydrofluoric acid solutions, respectively, and finally washed with pure water and dried to obtain a product in which no single-walled carbon nanotubes are found.
[0048] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.
Claims
1. A method for preparing single-walled carbon nanotubes, characterized in that: The method includes: Preheated oxygen-containing combustion-supporting gas is continuously introduced into the alloy tube from one end thereof, and the other end of the alloy tube is continuously pushed into the carbon material for combustion, and the carbon black product generated by the combustion of the alloy tube in the carbon material is collected to obtain the product.
2. The method for preparing single-walled carbon nanotubes according to claim 1, characterized in that: The oxygen-containing combustion-supporting gas contains no less than 25% oxygen by volume, has an inlet flow rate of 6-20 L / min, and a preheating temperature of 1000-1200°C.
3. The method for preparing single-walled carbon nanotubes according to claim 1 or 2, characterized in that: The carbon material is selected from at least one of metallurgical coke, graphite carbon bricks and semi-graphite carbon bricks.
4. The method for preparing single-walled carbon nanotubes according to claim 1 or 2, characterized in that: The alloy tube contains at least one metal element selected from the group consisting of Fe, Co, Ni and rare earth metals.
5. The method for preparing single-walled carbon nanotubes according to claim 4, characterized in that: The alloy tube is selected from at least one of a cobalt alloy tube, a nickel-cobalt alloy, an iron-cobalt-nickel alloy, a carbon steel tube and a nickel alloy tube.
6. The method for preparing single-walled carbon nanotubes according to claim 1 or 2, characterized in that: The wall thickness of the alloy tube is not greater than 2.5 mm.
7. The method for preparing single-walled carbon nanotubes according to claim 1 or 2, characterized in that: The outer diameter of the alloy tube is 6-10 mm.
8. The method for preparing single-walled carbon nanotubes according to claim 6, characterized in that: The wall thickness of the alloy tube is 0.5-2 mm.
9. The method for preparing single-walled carbon nanotubes according to claim 1 or 2, characterized in that: The method also includes washing the collected carbon black product with a nitric acid solution, a sodium hydroxide solution, a hydrofluoric acid solution and water in sequence, and obtaining single-walled carbon nanotubes after drying.
10. The method for preparing single-walled carbon nanotubes according to claim 9, characterized in that: The concentration of the nitric acid solution is 10-15wt%, the concentration of the sodium hydroxide solution is 40-50wt%, and the concentration of the hydrofluoric acid solution is 10-15wt%.