TW201012747A - Producing method for carbon nanotube - Google Patents

Abstract

The present invention provides a method for stably producing carbon nanotube which is stable in industrial on an industrial scale. This invention solves the aforementioned problem by a method of producing carbon nanotube by carrying pulse plasma discharge out between carbonic electrodes in the presence of catalyst in a solution. The catalyst is selected from the group consisted of the metals in group 6 to group 10 and compounds thereof.

Description

201012747 VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to a method for manufacturing a carbon nanotube. [Prior Art]

A carbon nanotube (hereinafter, abbreviated as CNT) is a structure in which a graphite sheet (a sheet in which carbon atoms are arranged in a hexagonal mesh shape) which is more equivalent to graphite is rounded into a cylindrical shape. It is known that CNTs have a single-walled CNT composed of one cylindrical graphite sheet and a plurality of multi-layered CNTs in which a plurality of cylindrical graphite sheets i are stacked in a concentric shape. Further, it is generally known that the protruding end of the CNT 9 immediately after the synthesis is formed into a structure in which a hemispherical graphite layer called a "cover" is closed. The CNT has a diameter of nm order and a length of #m~cm, and the aspect ratio (the length of the CNT divided by the same unit diameter) is extremely large, and has a characteristic that the curvature radius of the front end is extremely small from several nm to several tens of nm. CNTs are physically and mechanically tough, and are excellent in chemical properties and thermal stability. They correspond to the spiral structure of the cylindrical portion to form a metal or a semiconductor. Therefore, φ CNT is expected to be applied to an electronic wiring material for a light-emitting device, a heat dissipating material, a fiber material, an electron emission source for a flat panel display, a transistor material, and an electron emission source (point source) for an electron microscope. There are known methods for synthesizing CNTs: (1) Arc discharge between carbon rods in a gas atmosphere such as Ar or nitrogen 'Arc method for depositing CNTs on a cathode (see Patent Document 1), (2) Mixed catalysts The surface of the graphite touches a strong pulsed light such as a YAG laser, and the so-called soot is heated in an electric furnace, and a laser evaporation method for recovering CNTs on the downstream side of the reaction tube (refer to Patent Document 2), 201012747 (3) in the catalyst A chemical vapor phase growth method in which a low-boiling carbon compound such as methane, acetylene, carbon monoxide or benzene is thermally decomposed on a metal fine particle (see Patent Document 3, Patent Document 4, Non-Patent Document 1). [PRIOR ART DOCUMENT] [Patent Document 1] Japanese Laid-Open Patent Publication No. Hei. No. 2000-86217 (Patent Document 3) Patent Document 4] Japanese Patent Laid-Open Publication No. 2000-86218

W [Non-Patent Document] [Non-Patent Document 1] Chemical Physics Letters, Vol. 317, Nos. 497 to 503 (2000) [Summary of the Invention] According to the synthesis method of (1) and (2) Any of the obtained CNT systems completely forms a polymerization state toward a random direction. Further, there are cases in which a large amount of carbon nanocapsules and amorphous particles are contained. φ In addition, in order to generate an arc discharge or a pulsed light, high energy is required, and there is a problem that a high temperature is required and a manufacturing cost is high. According to the method of (3), C NT can be produced by a relatively stable method, but the raw materials are substances which are harmful and explosive, such as acetylene and carbon monoxide, or methane, etc., which are required to be stored as a high-pressure gas and have ignition danger. High substances and other issues. Further, when a liquid material such as benzene is used, it is necessary to vaporize it, and there is a problem that the attached equipment is large and complicated steps must be taken. Accordingly, it is an object of the present invention to provide a method for producing a carbon nanotube having an industrial scale and stably. In order to achieve the above object, the inventors of the present invention have repeatedly conducted an intensive review and found that CNTs can be obtained by generating a pulsed plasma between carbon-metal electrodes in the presence of a catalyst in a liquid, and the present invention has been achieved. That is, according to the present invention, there is provided: [1] A method for producing a carbon nanotube, which is characterized in that a pulsed plasma is discharged between carbon electrodes in the presence of a catalyst in a liquid. [2] The production method according to [1], wherein the catalyst is at least selected from the group consisting of metals of Groups 6 to 10 and a compound of the group of the long-period periodic table. According to the manufacturing method of the present invention, CNT can be produced with a lower energy (e.g., a low voltage). That is, in the manner of being carried out in a liquid, energy diffusion is suppressed and energy efficiency is improved, so that the object can be obtained by a low amount and a high reaction rate by a conventional technique. In general, CNT is formed on a metal catalyst, Although the state in which the catalyst component is attached to the product is observed, according to the present invention, it has been found that φ does not predict the effect of the conventional technique in which the product, that is, the CNT end does not remain in the catalyst. [Embodiment] The method for producing a carbon nanotube according to the present invention is characterized in that a pulsed plasma is discharged between carbon electrodes in the presence of a catalyst in a liquid. As the carbon electrode, any carbon material such as graphite, amorphous carbon or glass carbon can be used. The form of the electrode may be any of a rod shape, a wire shape, and a plate shape. Regarding the size of the two poles, either one of them may have a shape of a different size or the like. In addition, the two poles can be made of the same carbon material or different materials, and the 201012747 can be molded with a single or multiple carbon materials. The present invention is the production of CNTs in a liquid. The liquid (solvent) which can be used is not particularly limited as long as it does not affect the reaction. The liquid may be a mixture of two or more compounds. Examples of the usable liquid include saturated hydrocarbons such as hexane, octane, decane, cyclohexane, and cyclooctane, aromatic hydrocarbons of benzene, toluene, xylene, and naphthalene, water, methanol, ethanol, and C. Alcohol, butanol, ethylene glycol, propylene glycol, 1,4-butanediol and other alcohols, methyl acetate, ethyl acetate, butyl acetate, methyl benzoate, dimethyl phthalate and other esters, four Hydrogen

P ethers such as tetrahydropyran, dipropyl ether, dibutyl ether, diethylene glycol, and tetraethylene glycol. In view of dispersion, ignition, and oxidizability of the produced carbon product, it is preferred to use saturated hydrocarbons, aromatic hydrocarbons, and alcohols, and it is more preferable to use methanol or ethanol. The amount of liquid used is not particularly limited as long as the two electrodes are in the liquid. More preferably, the liquid does not scatter due to the generation of the plasma, or the liquid diffusibility is lost due to the concentration of the product. The present invention is directed to the manufacture of CNTs in the presence of a catalyst. As the catalyst, the Group 6 to Group 10 metal φ and its compound in the long period type periodic table are used. The catalyst may be used singly or in combination of two or more kinds at the same time or in stages. Examples of the Group 6 to Group 10 metals include iron group metals (i.e., iron, cobalt, nickel), chromium, molybdenum, rhodium, ruthenium, osmium, palladium, and platinum. As the catalyst shape, any of a plate shape, a wire shape, and a particle shape may be used. However, in consideration of the production efficiency of CNT, it is preferable to use a granular shape. The particle size of the granules to be used is not particularly limited, but the use of fine particles increases the CNT formation, so particles having a particle diameter of 1 nm to 100 #m are usually used, but in consideration of avoidance of agglutination or production efficiency, 2 nm to 50 # m is preferred, and particles of 5 nm to 10/zm are more preferred. 201012747 As a Group 6 to Group 10 metal compound, it is not specifically used, such as iron carbide, nickel carbide, cobalt carbide, molybdenum chloride, iron chloride, nickel chloride, cobalt chloride, palladium chloride, Platinum chloride, chromium bromide, molybdenum bromide, iron bromide, cobalt, cesium bromide, cesium bromide, palladium bromide, platinum bromide, cobalt sulphate, such as iron acetate, nickel acetate, Iron acetate butyrate, nickel butyrate, cobalt butyrate, iron lactate, iron lactate, nickel tartrate, cobalt tartrate, chromium, acenaphthylpyruvate, acenaphthylpyruvate, acetamidine Cobalt acid, ruthenium acetonate, ruthenium acetonate, ruthenium acetate, dicyclopentadienyl iron, dicyclopentadienyl cobalt, tetrakis(triphenylphosphine)palladium, etc. Metal complex such as metal wrong iron, nickel pentoxide or cobalt pentacarbonyl, etc. The catalyst can be dispersed or dissolved in a liquid, and can be dispersed. In view of the reaction efficiency, the amount of the φ catalyst to be used is not particularly limited as long as it is present in the concentration of the catalyst to be used in the carbon electrode, and the reaction conditions are not particularly limited. The temperature at which the pulsed plasma is discharged in the range of 0.01% by weight to 1% by weight in the case where the catalyst is dispersed or dissolved in the range of 0.001 m/L to 5 m/L. Not particularly limited, liquid type, but usually at room temperature ~ 300 ° (: range. Exceeding the vapor pressure of the solvent used, the solvent viscosity rises due to the temperature of the plasma being ignited below room temperature, due to damage Sexual tendency is not good. Don't limit, for example, such as chromium chloride, barium chloride, nickel chlorobromide, old iron bromide, nickel sulfate, cobalt, palladium acetate, cobalt lactate, wine such as acetamidine Nickel acid ketone, acetonitrile I ruthenium pyruvate, ethylenyl nickel, tricyclo compound, and ruthenium are also preferable in the carbon electrode, but it is also not particularly limited. The case where the plasma is produced in a liquid is mixed with The mixture is preferably mixed in the electrode. It is also inferior to the temperature of 300 ° C, and the product is diffused. 201012747 The voltage generated in the plasma is not particularly limited in the present invention, and is usually in the range of 50V to 500V. Taking into account the safety, the necessity of special devices, and in the 60V~4 00V The range is better, and the range of 80 V to 300 V is better. Further, the current generated by the plasma is not particularly limited, and is usually in the range of 0.1 to 20 A, and is preferably in the range of 0.2 to 10 A in consideration of energy efficiency. The pulse interval of the pulsed plasma discharge is not particularly limited, but it is preferably 5 to 100 milliseconds, and the cycle of 6 to 50 milliseconds is better. The duration of each pulse plasma discharge is also caused by the voltage and current generated by the plasma. However, it is usually in the range of 1 to 50 microseconds, and it is preferably in the range of 2 to 30 microseconds in consideration of the discharge efficiency. In the present invention, vibration may be applied to the electrodes, and the electrodes may be provided by vibrating the electrodes. The carbon compound which is precipitated is not retained, and it is preferable to discharge efficiently. The method of imparting vibration is not particularly limited, and a method of periodically imparting vibration or a method of intermittently imparting vibration may be employed. In the vibration means, it is preferable to use an electric actuator to stabilize the amplitude of the vibration and the distance between the electrodes. The environment for carrying out the present invention can be either under reduced pressure, under pressure, or under normal pressure. Implementation However, in view of safety and operability, it is preferably carried out under an inert gas such as nitrogen or argon. The CNTs produced by the method of the present invention are deposited in a liquid, so that the general method can be, for example, after performing a filtration operation. The CNT is obtained by removing the used liquid by a pressure reduction operation or the like. The CNT system obtained as described above generally has a tube diameter in the range of 7. 7 to 50 nm and a tube length in the range of 50 nm to 10 # m, but According to the conditions, the size outside the range can also be obtained. 201012747 The aspect ratio of the CNT and the curvature of the front end can be generated by appropriately adjusting the voltage generated by the plasma, the current generated by the plasma, the pulse interval of the discharge, and the pulse discharge of each pulse. Change in duration. EXAMPLES Example 1 200 g of absolute ethanol and 1.000 g of iron (III) acetate were weighed in a beaker having a capacity of 300 ml, and ultrasonic dispersion was carried out for 15 minutes. A cylindrical graphite electrode having a diameter of 6 legs and a length of 100 mm mm (more than 99% purity) was inserted into the obtained solution, and the electrodes were fixed to .l mm, and the electrodes were vibrated by an electric actuator. Each electrode was connected to an AC power source, and pulse plasma discharge was performed at 200 V and 2 Torr. The pulse interval is 20 milliseconds and the duration of each pulsed plasma discharge is performed at 10 microseconds. At the same time as the discharge was started, it was observed that the black powder was dispersed in the liquid to cause a reaction. The reaction was continued for 30 minutes, and after the reaction, ethanol was distilled off, and 20 g of nitric acid was added to the residue to oxidize and decompose the amorphous portion. Using 200 g of ion-exchanged water, the oxidative decomposition product was washed and removed, and dried under reduced pressure at 10 ° C to obtain 3.14 g of a black powder. φ The TEM photograph (magnification: 100,000 times) of the obtained black powder is shown in Fig. 1. From the TEM photograph, the obtained black powder was a CNT having a diameter of about 3 nm. The CNT yield was 48% as calculated by dividing the weight loss of the electrode into 100% of the reaction. [Example 2] In Example 1, the operation in the same manner as in Example 1 was carried out except that iron acetate (barium) was used as the catalyst except that graphite containing 1% by weight of iron was used as the electrode. The TEM photograph of the obtained black powder is shown in Fig. 2 (magnification: 100,000 times). The black powder obtained from the TEM photograph was a CNT having a diameter of about 4 nm from 10 to 201012747. Example 3 The operation of Example 1 was carried out in the same manner as in Example 1 except that 〇.〇〇lg of iron (III) acetate was used, except that 〇.〇〇lg acetyl acetonate pyruvate was used. A TEM photograph (magnification: 100,000 times) of the obtained black powder is shown in Fig. 3. The black powder obtained from the TEM photograph was a CNT having a diameter of about 6 nm. The same operation as in Example 1 was carried out except that 200 g of anhydrous ethanol was used in the first embodiment except that 200 g of hydrazine-exchanged water was used instead of the solvent. A TEM photograph (magnification: 1 million times) of the obtained black powder is shown in Fig. 4. The black powder obtained from the TEM photograph was judged to be a CNT having a tube diameter of about 4 nm. Observation results of TEM-EDX (transmission electron microscope-g-dispersive X-ray spectroscopy) were observed by TEM-EDX (TEM: JEOL JEM-3 00 0F, EDX: System SIX, manufactured by NORAN) In the CNTs obtained in the above Examples 1 to 4, no metal element was observed. From this case, it was found that the catalyst gold was attached to the product φ. Comparative Example 1 Ultrasonic dispersion was carried out for 15 minutes by weighing 200 g of absolute ethanol and 0.001 g of iron (III) acetate in a 300 ml beaker. A cylindrical graphite electrode having a diameter of 6 faces and a length of 100 legs (purity of 99% or more) was inserted into the obtained solution, and the electrodes were fixed to 1 mm therebetween, and an electric actuator was used to impart vibration to the electrodes. Each electrode was connected to a DC power source and continuously discharged at 200 V and 2 A. At the same time as the discharge was started, it was observed that the black powder was dispersed in the liquid to cause a reaction. The reaction was continued for 30 minutes, the solution was centrifuged, and an appropriate amount of absolute ethanol was added thereto for washing and separation in -11-201012747. In the same manner as in the examples, when the amorphous portion was decomposed and washed with ion-exchanged water to remove the oxidative decomposition product, no black powder remained, and it was judged that no CNT was formed. According to the manufacturing method of the present invention, it is possible to manufacture a carbon nanotube by using a low voltage and the like with low energy, which is industrially useful. [Fig. 1] Fig. 1 is a black powder obtained in Example 1. Transmitted electron microscope (TEM) photograph (magnification: 100,000 times). Fig. 2 is a TEM photograph (magnification: 100,000 times) of the black powder obtained in Example 2. Fig. 3 is a TEM photograph (magnification: 100,000 times) of the black powder obtained in Example 3. Fig. 4 is a TEM photograph (magnification: 100,000 times) of the black powder obtained in Example 4. [Main component symbol description] None. 12-

Claims (1)

201012747 VII. Patent application scope: ι· A method for manufacturing a carbon nanotube, which is characterized by: discharging a pulsed plasma between carbon electrodes in the presence of a catalyst in a liquid. 2. The method for producing a carbon nanotube according to claim 1, wherein the catalyst is at least one metal selected from the group consisting of Group 6 to Group 10 of the long period type periodic table and a compound thereof. Group.