JP4556409B2 - Method for purifying composition containing carbon nanotube and carbon nanotube composition - Google Patents

Description

  Since carbon nanotubes have high mechanical strength and high conductivity, they can be used for negative electrodes for fuel cells and lithium secondary batteries, high-strength resins composed of composite materials with resins and organic semiconductors, conductive resins, and electromagnetic shielding materials. It is expected as a material, and further, as L / D (length / diameter ratio) is large and the diameter is several nm, it is expected as a material for probes for scanning tunneling microscopes, field electron emission sources, and nanotweezers. In addition, since it has a nano-sized space, it is expected as a material for adsorption materials, medical nanocapsules, and MRI contrast agents.

  The present invention relates to a method for purifying a composition containing carbon nanotubes to obtain a carbon nanotube suitable for the above use, and a carbon nanotube composition suitable for the above use.

  The carbon nanotube has a shape in which one surface of graphite is wound into a cylindrical shape. A single-walled carbon nanotube is wound in one layer, a double-walled carbon nanotube is wound in two layers, and is wound in multiple layers. This was called multi-walled carbon nanotube. Since carbon nanotubes have high mechanical strength and high conductivity, they can be used for negative electrodes for fuel cells and lithium secondary batteries, high-strength resins composed of composite materials with resins and organic semiconductors, conductive resins, and electromagnetic shielding materials. It is expected as a material, and further, as L / D (length / diameter ratio) is large and the diameter is several nm, it is expected as a material for probes for scanning tunneling microscopes, field electron emission sources, and nanotweezers. In addition, since it has a nano-sized space, it is expected as a material for adsorption materials, medical nanocapsules, and MRI contrast agents. In any application, high-purity carbon nanotubes are required. As carbon nanotubes, single-walled carbon nanotubes with a small diameter or 2 to 5 carbon nanotubes are advantageous. Excellent.

  Known methods for producing carbon nanotubes include arc discharge, laser evaporation, and chemical vapor deposition (see Non-Patent Document 1). Among them, high quality carbon nanotubes with few defects in the graphite layer are inexpensive. As a manufacturing method, catalytic chemical vapor deposition is known (see Non-Patent Document 2). Furthermore, it is known that the catalytic chemical vapor deposition method can be produced by controlling the number of carbon nanotube layers to be a single layer or 2 to 5 layers (see Non-Patent Document 3). In any of the production methods, a catalyst metal is often required for the production of carbon nanotubes. For this reason, the composition containing the carbon nanotube obtained by the said manufacturing method contains a catalyst metal as impurities other than a carbon nanotube. For example, the arc discharge method, the laser evaporation method, and the chemical vapor deposition method include a catalytic metal, and the catalytic chemical vapor deposition method includes a solid catalyst composed of a catalytic metal and a solid support. Further, the composition containing carbon nanotubes obtained by the above production method is not limited to a solid catalyst (in the case of only catalytic metal or in the case of consisting of a catalytic metal and a solid support, it is generically referred to as a solid catalyst). In many cases, carbon impurities including graphite fine particles are included. For this reason, the refinement | purification method which removes these impurities from the composition containing the carbon nanotube obtained by the said manufacturing method is needed. Conventionally proposed purification methods include, for example, a method of contacting with hydrofluoric acid to remove the solid support (see Non-Patent Document 4), and a method of contacting with hydrochloric acid to remove the catalytic metal (Non-Patent Document 4). And a method of reacting with oxygen at a high temperature to remove amorphous carbon (see Non-Patent Document 1).

  However, the conventional purification method has a problem that a defect occurs in the graphite layer constituting the carbon nanotube, and the heat resistance, mechanical strength, and conductivity of the carbon nanotube are lost. For this reason, even if a carbon nanotube was used as a material for the above-mentioned application, a sufficient effect could not be obtained. In particular, single-walled and 2- to 5-walled carbon nanotubes, which are expected to be optimal for the materials for the above-mentioned applications, have been serious problems such as significant damage to the carbon nanotubes and a significant reduction in yield.

  Furthermore, the conventional purification method is a method for removing a solid catalyst contained in a composition containing carbon nanotubes, and it is desired to recover and reuse the solid catalyst from the viewpoint of cost and environmental problems. Among these, in the catalytic chemical vapor deposition method in which the solid catalyst is an important technology, it is expected to recover and reuse the solid catalyst contained in the composition containing carbon nanotubes.

Moreover, since the carbon nanotube used for the said use has the characteristic excellent in the one where there are few entanglements between carbon nanotubes, the carbon nanotube composition with few entanglements between carbon nanotubes is desired. Furthermore, since a composition containing carbon nanotubes is provided to the market as a powder having a very low bulk density, there is a problem in handling dust, and improvement in workability is expected.
Yahachi Saito, Shunji Bando, Fundamentals of Carbon Nanotubes, Corona Inc., p17, 23, 47 Chemical Physics Letters 303 (1999), 117-124 Chemical Physics Letters 360 (2002), 229-234 Applied Physics A 74 (2002), 345-348 Materials Letters 57 (2002), 734-738

  The present invention has been made in view of the above circumstances, and can obtain carbon nanotubes excellent in heat resistance, mechanical strength, and conductivity with high purity. Furthermore, the solid catalyst can be recovered and reused. It is an object of the present invention to provide a method for purifying a composition containing carbon nanotubes, and to provide a carbon nanotube composition having excellent workability and excellent workability.

  In order to achieve the above object, the present invention mainly has the following configuration.

The composition containing carbon nanotubes, immersed in the liquid which is divided into two or more layers, the solution portion contains many carbon nanotubes, by recovering individual solution portions containing many components other than carbon nanotubes, carbon A method for purifying a composition containing carbon nanotubes, characterized by increasing the purity of the nanotubes, wherein at least one of the two or more layers is a liquid selected from the following (A): This layer is a method for purifying a composition containing carbon nanotubes, wherein the layer contains an organic solvent having an SP value of 13.4 or less. In this way, carbon nanotubes excellent in heat resistance, mechanical strength, and conductivity can be obtained with high purity.
(A) Water, a sodium chloride aqueous solution having a sodium chloride concentration of 0.1 wt% or more, an acidic aqueous solution having a pH of 6 or less, and an alkaline aqueous solution having a pH of 8 or more .

Furthermore, the compound represented by the general formula (1) is
l = represents an allowed integer with a valence of 5 or more m = represents an allowed integer with a valence of 5 or more n = 0
By being characterized by this, the purification efficiency of carbon nanotubes can be further improved.

  Moreover, the refinement | purification efficiency of a carbon nanotube can be improved because the liquid in which the composition containing a carbon nanotube is immersed in the liquid divided into two or more layers. Among them, the difference in solubility parameter (SP value) of the liquids constituting each layer is 10 or more, the liquid contains 5 to 95% by weight of water, and the chloride is 0.1% by weight or more in place of sodium chloride instead of water. By including an aqueous sodium solution, an acidic aqueous solution having a pH of 6 or lower, and an alkaline aqueous solution having a pH of 8 or higher, the purification efficiency of carbon nanotubes can be improved.

  In addition, after the composition containing carbon nanotubes is immersed in a liquid, the solution part containing a lot of carbon nanotubes and the solution part containing a lot of components other than the carbon nanotubes contained in the composition containing carbon nanotubes are individually collected. The purification efficiency of the carbon nanotubes can be improved by performing a stirring process, an ultrasonic process, and a centrifugal process before the process.

  Furthermore, after making oxygen contact the composition containing a carbon nanotube at 200-800 degreeC, the refinement | purification efficiency of a carbon nanotube can be improved by immersing in a liquid.

And the purification method of the composition containing a carbon nanotube as described above achieves the purification method of a composition containing a carbon nanotube that satisfies the following requirements (1) and (2), and thus has purity. The carbon nanotubes with improved resistance are excellent in heat resistance, mechanical strength, and conductivity. (1) a maximum peak intensity in the range of 1550～1650Cm ^-1 in spectrum obtained by measurement of the resonance Raman scattering measurement method G, a maximum peak intensity in the range of 1300～1400Cm ^-1 is D The relationship of the Raman G / D ratio (RII) of the carbon nanotubes with increased purity after purification to the Raman G / D ratio (RI) of the composition containing the carbon nanotubes before purification is RII ≧ RI. (2) When a thermal analysis is performed up to 900 ° C. by raising the temperature at 10 ° C./min in the air atmosphere, the composition containing a carbon nanotube before purification having an exothermic peak in the temperature range of 300 to 900 ° C. The relationship between the exothermic peak temperature (TI) and the exothermic peak temperature (TII) of the carbon nanotube with increased purity after purification is TII ≧ TI.

  When the composition containing carbon nanotubes is characterized by containing a solid catalyst, not only the purity of the carbon nanotubes can be increased by the method of the present invention, but also the solid catalyst can be recovered and reused. The effect is great. In particular, when the solid catalyst is a form in which a catalytic metal is supported on a solid support, and the solid support is zeolite, the effect is very large. As described above, the present invention recovers a solution part containing a large amount of a solid catalyst out of a solution part containing a large amount of components other than carbon nanotubes contained in a composition containing carbon nanotubes, and reuses the solid catalyst. It is related also to the purification method of the carbon nanotube characterized by this.

  Single-walled and 2-5-walled carbon nanotubes have a small number of layers, and heat purification, mechanical strength, and electrical conductivity are remarkably lost and the yield is greatly reduced by conventional purification methods. The method for purifying a composition containing carbon nanotubes according to the present invention is particularly effective for a composition containing single-walled or 2-5-layered carbon nanotubes.

Further, the present invention is a carbon nanotube composition in which the carbon nanotube is contained in the liquid 0.01% by weight or more, and the bulk density of the carbon nanotube in the liquid is 50 g / liter or less, the composition comprising: The present invention also relates to a carbon nanotube composition obtained from a solution portion containing a large amount of carbon nanotubes recovered in the method for purifying a composition containing carbon nanotubes . Such a carbon nanotube composition has little entanglement between carbon nanotubes, a negative electrode material for a fuel cell or a lithium secondary battery, a high-strength resin composed of a composite material with a resin or an organic semiconductor, a conductive resin, or an electromagnetic shielding material. It is suitable as a material for the above, a scanning tunneling microscope probe, a field electron emission source, a nanotweezer material, an adsorbing material, a medical nanocapsule, and an MRI contrast agent material. Furthermore, there is no troublesome handling due to dust, and workability is excellent.

Furthermore, the liquid containing the carbon nanotubes, involved in the carbon nanotube composition, wherein the compound represented by the following general formula (1) viewed contains one or more, and a liquid which is divided into two or more layers .
ClHmXn (1)
X = substituent containing any one of halogen, O, N, and S = 1 = representing an allowable integer of 1 or more valence m = 0 or n = 0 representing an allowable integer of 1 or more valence This represents an acceptable integer having a valence of 1 or more, except when n = m = 0. Such a composition has less entanglement between carbon nanotubes and is excellent in application characteristics.

In addition, the compound represented by the general formula (1)
X = OH
l = representing a permissible integer of a valence of 4 or more m = representing a permissible integer of a valence of 4 or more n = 1 representing a permissible integer of a valence of 1 or more, Also involved in carbon nanotube compositions.

Furthermore, the compound represented by the general formula (1) is
l = represents an allowed integer with a valence of 5 or more m = represents an allowed integer with a valence of 5 or more n = 0
It also relates to a carbon nanotube composition, characterized in that

  In particular, these compositions preferably contain single-walled or 2-5-layered carbon nanotubes because of excellent application characteristics.

  Moreover, these compositions can be easily obtained by the purification method of the composition containing the carbon nanotube of the present invention.

According to the present invention, a composition containing carbon nanotubes is immersed in a liquid containing one or more compounds represented by the following general formula (1), a solution part containing a large amount of carbon nanotubes, and a composition containing carbon nanotubes The purity of the carbon nanotubes can be increased by individually collecting the solution portions containing a large amount of components other than the carbon nanotubes contained in the.
ClHmXn (1)
X = substituent containing any one of halogen, O, N, and S = 1 = representing an allowable integer of 1 or more valence m = 0 or n = 0 representing an allowable integer of 1 or more valence Represents an acceptable integer of one or more valences, except when n = m = 0. Furthermore, when the composition containing carbon nanotubes is characterized by containing a solid catalyst, the solid catalyst is recovered and recycled. It can be used.

  The carbon nanotube composition is characterized in that the carbon nanotube composition contains 0.01% by weight or more of carbon nanotubes and the bulk density of the carbon nanotubes in the liquid is 50 g / liter or less. Low fit, excellent workability, anode material for fuel cells and lithium secondary batteries, high-strength resin composed of composite material with resin and organic semiconductor, conductive resin, electromagnetic shielding material, for scanning tunnel microscope It is suitable as a material for probes, field electron emission sources, nanotweezer materials, adsorbent materials, medical nanocapsules, and MRI contrast agents.

The method for purifying a composition containing carbon nanotubes of the present invention comprises immersing a composition containing carbon nanotubes in a liquid containing one or more compounds represented by the following general formula (1), and a solution part containing a large amount of carbon nanotubes. And the purity of a carbon nanotube is improved by collect | recovering individually the solution part which contains many components other than the carbon nanotube contained in the composition containing a carbon nanotube. In this way, carbon nanotubes having excellent heat resistance, mechanical strength, and conductivity can be obtained with high purity.
ClHmXn (1)
X = substituent containing any one of halogen, O, N, and S = 1 = representing an allowable integer with a valence of 1 or more m = 0 or n = 0 representing an allowed integer with a valence of 1 or more It represents an acceptable integer having a valence of 1 or more, except when n = m = 0. Although it will be described in detail below, the method for purifying a composition containing carbon nanotubes according to the present invention includes carbon nanotubes and fullerenes. A technique different from the method in which a carbon nanotube and fullerene are separated by solid-liquid separation by contacting a composition containing benzene with an organic solvent such as toluene, benzene or hexane and utilizing the difference in solubility between the carbon nanotube and fullerene. It is.

  The carbon nanotube has a shape in which one surface of graphite is wound into a cylindrical shape. A single-walled carbon nanotube is wound in one layer, a double-walled carbon nanotube is wound in two layers, and is wound in multiple layers. This was called multi-walled carbon nanotube. The form of the carbon nanotube can be examined with a high-resolution transmission electron microscope. The graphite layer is preferred so that it can be seen straight and clearly in a transmission electron microscope, but the graphite layer may be disordered. What disturbs the graphite layer may be defined as carbon nanofiber, and such carbon nanofiber is also included in the carbon nanotube in the present invention.

  Known methods for producing carbon nanotubes include arc discharge method, laser evaporation method, chemical vapor deposition method, etc. Among them, as a method for producing high-quality carbon nanotubes with few defects in the graphite layer at low cost, Chemical vapor deposition is known. Furthermore, it is known that catalytic chemical vapor deposition can be produced by controlling the number of carbon nanotube layers to be a single layer or 2 to 5 layers. The composition containing the carbon nanotube obtained by the said manufacturing method contains impurities other than a carbon nanotube. For example, arc discharge method, laser evaporation method, chemical vapor deposition method includes carbon impurities such as amorphous carbon and solid catalyst (consisting only of catalytic metal), and catalytic chemical vapor deposition method uses solid catalyst (catalyst metal and solid). Comprising a carrier).

  The method for purifying a composition containing carbon nanotubes in the present invention is effective for a composition containing carbon nanotubes containing the following impurities. For example, a solid support made of an inorganic material such as amorphous silica, crystalline silica, alumina, zeolite, asbestos, glass fiber, a typical metal element of group 1 to group 16 specified in the periodic table, and a transition metal element And carbon impurities such as metals containing metal elements selected from these, metal oxides thereof, amorphous carbon and fine graphite particles called nanoparticles.

  Carbon impurities such as amorphous carbon and nanoparticles have many functional groups such as a hydroxyl group, a carboxyl group, and a carbonyl group because of their structure, and can be considered to be easily dispersed in a highly polar solvent. In the method for purifying a composition containing carbon nanotubes in the present invention, separation and purification of carbon nanotubes and carbon impurities can be achieved by utilizing the difference in affinity between carbon nanotubes and a solvent for carbon impurities. Furthermore, for the same reason, separation and purification of carbon nanotubes with many structural defects and carbon nanotubes with few structural defects can be achieved. Moreover, the modified carbon nanotube which provided the functional group to the graphite layer of the carbon nanotube, and the untreated carbon nanotube can be separated and purified.

  Normally, a composition containing carbon nanotubes contains a solid catalyst used when producing carbon nanotubes. Similarly, by utilizing the difference in affinity between the carbon nanotubes and the solvent of the solid catalyst. Separation and purification of the carbon nanotube and the solid catalyst are achieved. Further, separation and purification of the carbon nanotube and the solid catalyst can be achieved also by utilizing the difference in specific gravity between the carbon nanotube and the solid catalyst.

  The reason why carbon nanotubes excellent in heat resistance, mechanical strength, and conductivity can be obtained by the method for purifying a composition containing carbon nanotubes of the present invention will be described below. The graphite layer of the carbon nanotube is composed of a carbon six-membered ring, and the surface of the graphite layer is covered with pi electrons. If there is a structural defect in the graphite layer of the carbon nanotube due to a lack of carbon atoms, the heat resistance and mechanical strength of the carbon nanotube are lowered. In addition, if there are electronic defects due to unpaired electron pairs, functional groups, and deposits in the graphite layer of the carbon nanotube, the conductivity of the carbon nanotube is lowered. That is, if the graphite layer of the carbon nanotube has many structural defects and electronic defects, the heat resistance, mechanical strength, and conductivity of the carbon nanotube are lost. Since the method for purifying a composition containing carbon nanotubes in the present invention does not require an extreme acid treatment as in the prior art, structural defects and electronic defects are not generated in the graphite layer of carbon nanotubes. Purity can be increased. Such carbon nanotubes are used for negative electrodes for fuel cells and lithium secondary batteries, high-strength resins made of composite materials with resins and organic semiconductors, conductive resins, electromagnetic shielding materials, probes for scanning tunneling microscopes, field electron emission. It can be a material suitable for applications such as a source, nanotweezers, adsorption material, medical nanocapsule, and MRI contrast agent.

The defect of the graphite layer of the carbon nanotube can be evaluated by, for example, the following method. In the spectrum obtained by measuring of resonance Raman scattering measurement method, a maximum peak intensity in the range of 1550~1650cm ^-1 G, the maximum peak intensity is D within the 1300~1400cm ^-1, G / D ratio can be evaluated. G is a peak attributed to the graphite structure, D is a peak attributed to a defect in the graphite structure, and if the graphite structure has many defects, the G / D ratio decreases. That is, it is considered that a carbon nanotube having a larger G / D ratio has fewer defects in the graphite layer and is superior in heat resistance, mechanical strength, and conductivity. In addition, when a thermal analysis is performed up to 900 ° C. by raising the temperature at 10 ° C./min in the air atmosphere, the evaluation can be made with an exothermic peak temperature in the range of 300 to 900 ° C. When there are many defects in the graphite layer of the carbon nanotube, the exothermic peak temperature becomes low. That is, it is considered that a carbon nanotube having a higher exothermic peak temperature has fewer defects in the graphite layer and is superior in heat resistance, mechanical strength, and conductivity. From this, the purified carbon nanotube composition obtained by the method for purifying a composition containing carbon nanotubes of the present invention has the same G / D ratio and exothermic peak temperature as the composition containing carbon nanotubes before purification. In this case, it is considered that the purity of the carbon nanotube could be increased without causing structural defects and electronic defects in the graphite layer of the carbon nanotube. Further, when the purified carbon nanotube composition obtained by the method for purifying a composition containing carbon nanotubes of the present invention has a larger G / D ratio than the composition containing carbon nanotubes before purification, When the temperature is high, it is considered that separation and purification of carbon nanotubes and carbon impurities, and separation and purification of carbon nanotubes with many structural defects and carbon nanotubes with few structural defects were achieved.

  Hereinafter, the operation of the method for purifying a composition containing the carbon nanotube of the present invention will be described more specifically. A liquid containing one or more kinds of compounds represented by the general formula (1) is put in a container, and a composition containing carbon nanotubes is put into the container and allowed to stand. After a while, it is divided into a solution part containing a lot of carbon nanotubes and a solution part containing a lot of components other than carbon nanotubes. For example, the solution part containing a large amount of carbon nanotubes is the bottom part (precipitation), and the solution part containing many components other than carbon nanotubes is the top part (supernatant). By individually collecting the top and bottom of the solution, the purity of the carbon nanotube can be increased. The solution part containing a large amount of recovered carbon nanotubes is again added to a liquid containing one or more compounds represented by the general formula (1), and after standing, the solution part containing many carbon nanotubes and components other than carbon nanotubes It is also possible to individually collect the solution portions containing a large amount of carbon and further increase the purity of the carbon nanotubes. Moreover, the solution part containing many recovered carbon nanotubes can be solid-liquid separated to obtain carbon nanotubes with increased purity as a solid. Similarly, a solution part containing a large amount of components other than the recovered carbon nanotubes is added again to a liquid containing one or more compounds represented by the general formula (1), and after standing, In addition, each of the solution parts containing a large amount of components other than carbon nanotubes can be individually collected, and the recovery rate of carbon nanotubes can be increased, or the solution part containing many components other than the collected carbon nanotubes can be solid-liquid separated, Components other than carbon nanotubes can also be obtained as a solid.

  In addition, carbon nanotubes having increased purity obtained by the method for purifying a composition containing carbon nanotubes of the present invention are brought into contact with an acidic aqueous solution or an alkaline aqueous solution, and the remaining solid catalyst is removed to further increase the purity of the carbon. Nanotubes can also be obtained. At this time, since the amount of the solid catalyst contained in the carbon nanotubes with increased purity obtained by the method for purifying a composition containing carbon nanotubes of the present invention is small, the conditions for acid treatment and alkali treatment can be made mild. Thus, it is possible to obtain a carbon nanotube excellent in application characteristics with few defects. As the kind of acidic aqueous solution, aqueous solutions such as hydrofluoric acid, sulfuric acid, hydrochloric acid, and nitric acid can be used, and these may be used alone or in combination of two or more. As a kind of alkaline aqueous solution, aqueous solution, such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, ammonia, can be used, for example. These may be used alone or in combination.

The compound represented by the general formula (1) used in the present invention is:
ClHmXn (1)
X = substituent containing any one of halogen, O, N, and S = 1 = representing an allowable integer of 1 or more valence m = 0 or n = 0 representing an allowable integer of 1 or more valence Represents an acceptable integer of 1 or more valence, except when n = m = 0, preferably l = 1 to 10, m = 0 to 22, n = 0 to 10 (where n = m = 0 is excluded), and more preferably in the range of l = 1 to 6, m = 0 to 14, n = 0 to 6 (except when n = m = 0).

And the compound shown by General formula (1) is
X = OH
l = 1 represents an acceptable integer with a valence of 1 or more, m = represents an acceptable integer with a valence of 3 or more, n = 1 represents an acceptable integer with a valence of 1 or more, more preferably l = 1-10, m = 3-22, n = 1-10, more preferably l = 1-6, m = 3-14, n = 1-6, and by using such a compound, carbon The purification efficiency of the nanotube can be improved.

Furthermore, the compound represented by the general formula (1) is:
l = represents an allowed integer with a valence of 5 or more m = represents an allowed integer with a valence of 5 or more n = 0
More preferably, l = 5 to 10, m = 5 to 22, n = 0, still more preferably l = 5 to 6, m = 5 to 14, and n = 0. By using it, the purification efficiency of carbon nanotubes can be further improved.

  Specific examples of the compound represented by the general formula (1) include inorganic compounds such as carbon disulfide and carbon tetrachloride, pentane, n-hexane, cyclohexane, isooctane, octane, benzene, toluene, xylene, and the like. Hydrocarbon compounds, chloroform, 1,2-dichloroethane, 1,2-dibromoethane, trichloroethylene, tetrachloroethylene, chlorobenzene, bromobenzene, o-dichlorobenzene, methyl iodide, ethyl iodide, and other halogen compounds, methanol, ethanol, 1 -Propanol, 2-propanol, 2,2,2-trifluoroethanol, 1-butanol, 2-butanol, isobutyl alcohol, isopentyl alcohol, n-hexanol, cyclohexanol, ethylene glycol, propylene glycol 2-methoxyethanol, 2-ethoxyethanol, phenol, benzyl alcohol, cresol, diethylene glycol, triethylene glycol, glycerol and other alcohols and phenols, diethyl ether, diisopropyl ether, tetrahydrofuran, tetrahydropyran, 1,4-dioxane, anisole, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, dicyclohexyl-18-crown-6, ethers such as methyl carbitol, ethyl carbitol, aldehydes and ketones such as furfural, acetone, ethyl methyl ketone, cyclohexanone, formic acid, acetic acid, Acetic anhydride, trichloroacetic acid, trifluoroacetic acid, ethyl acetate, butyl acetate, ethylene carbonate, propylene carbonate, formamide, N-methyl Acids and derivatives such as formamide, N, N-dimethylformamide, N-methylacetamide, N, N-dimethylacetamide, nitriles such as acetonitrile, propionitrile, succinonitrile, benzonitrile, nitromethane, nitrobenzene, ethylenediamine, pyridine Nitro compounds and amines such as piperidine, morpholine, t-pentylamine, hexylamine and aniline, and sulfur compounds such as dimethyl sulfoxide and sulfolane.

  More preferable compounds include, for example, methanol, ethanol, 1-propanol, 2-propanol, 2,2,2-trifluoroethanol, 1-butanol, 2-butanol, isobutyl alcohol, isopentyl alcohol, n-hexanol, and cyclohexanol. And alcohol / phenols such as ethylene glycol, propylene glycol, 2-methoxyethanol, 2-ethoxyethanol, phenol, benzyl alcohol, cresol, diethylene glycol, triethylene glycol, and glycerin.

  More preferable compounds include hydrocarbon compounds such as pentane, n-hexane, cyclohexane, isooctane, octane, benzene, toluene and xylene.

  Particularly preferred compounds include, for example, pentanol, n-hexanol, cyclohexanol, n-hexane, and cyclohexane.

  When the composition containing carbon nanotubes is immersed in a liquid containing one or more compounds represented by general formula (1), the amount of the composition containing carbon nanotubes and one or more compounds represented by general formula (1) are contained. The amount of the liquid is 1 to 1000 ml, preferably 2 to 500 ml, and more preferably 2 to 500 ml, with respect to 1 g of the composition containing carbon nanotubes. Preferably it is 5-200 ml.

  The container for containing a liquid containing one or more compounds represented by the general formula (1) is not particularly limited as long as it is a chemical-resistant container. For example, glass, polypropylene, polyethylene, polyvinyl chloride, Teflon, A container made of FRP or CFRP can be used. In particular, it is preferable to use a container having a structure that allows easy liquid separation because the operation of individually collecting the solution part containing a large amount of carbon nanotubes and the solution part containing a large amount of components other than carbon nanotubes is facilitated. For small amounts of handling (laboratory level handling), you can use well-known instruments such as beakers and Erlenmeyer flasks. Especially, when using a separatory funnel, a solution part containing a lot of carbon nanotubes, and other than carbon nanotubes The operation of individually recovering the solution parts containing a large amount of these components is facilitated, which is preferable.

  Furthermore, the purification efficiency of a carbon nanotube can be improved by making the liquid which immerses the composition containing a carbon nanotube into a liquid which contains two or more types of components and was divided into two or more layers. The reason for this is that two or more layers of a liquid layer having a strong affinity for carbon nanotubes and a liquid layer having a strong affinity for carbon impurities and a solvent for a solid catalyst are used for liquid-liquid separation of each layer. This is because the solution part containing a large amount of carbon nanotubes and the solution part containing a large amount of impurities other than the carbon nanotubes can be collected individually with ease and high efficiency.

  Above all, when the difference in solubility parameter (SP value) of the liquid constituting each of the liquids divided into two or more layers is 10 or more, the difference in affinity between the carbon nanotube and the carbon impurity and the solvent of the solid catalyst is further increased. Can be actively used. The difference in SP value is more preferably 15 or more. For example, when a liquid separated into two layers of water and an organic solvent is used, since the SP value of water is 23.4, it is preferable to use an organic solvent having an SP value of 13.4 or less, and an SP value of 8 It is more preferable to use an organic solvent of .4 or less. More specifically, for example, a combination of water and a hydrocarbon compound, which is preferably a combination of water and pentanol, water and n-hexanol, water and cyclohexanol, water and cyclohexane, water and n-hexane. A combination of water and cyclohexane, water and n-hexane is particularly preferred.

  And since water has a large polarity, when water is included as a liquid in which the composition containing carbon nanotubes is immersed, the carbon nanotubes, carbon impurities, and solid catalyst can be recovered individually and efficiently. In particular, as described above, it is effective to use a liquid separated into at least two layers of water and an organic solvent. Moreover, water is effective in terms of cost. The ratio of water in the liquid containing one or more compounds represented by the general formula (1) soaking the composition containing carbon nanotubes is preferably 5 to 95% by weight, more preferably 20 to 90% by weight. It is particularly preferably 30 to 80% by weight.

  In addition, if a sodium chloride aqueous solution with a sodium chloride concentration of 0.1 wt% or more is used instead of water as a liquid for immersing the composition containing carbon nanotubes, the carbon nanotubes, carbon impurities, and solid catalyst are more efficiently recovered individually. it can. In particular, as described above, it is effective to use a liquid separated into at least two layers of an aqueous sodium chloride solution and an organic solvent. Compared with water, the recovery efficiency of carbon nanotubes is improved by using a sodium chloride aqueous solution due to the effect of salting out. The ratio of the sodium chloride aqueous solution in the liquid containing one or more compounds represented by the general formula (1) soaking the composition containing carbon nanotubes is preferably 5 to 95% by weight, more preferably 20 to 90% by weight. %, Particularly preferably 30 to 80% by weight. The concentration of the sodium chloride aqueous solution is preferably 0.1 wt% or more, preferably 1 wt% or more, and more preferably 5 wt% or more because the salting out effect can be enhanced.

  Furthermore, when an acidic aqueous solution having a pH of 6 or less is included instead of water as a liquid in which the composition containing carbon nanotubes is immersed, the zeta potential of the composition containing carbon nanotubes can be adjusted, and aggregation of carbon nanotubes and solid catalysts can be prevented. The carbon nanotubes, carbon impurities, and solid catalyst can be recovered individually and efficiently. In particular, as described above, it is effective to use a liquid separated into at least two layers of an acidic aqueous solution and an organic solvent. As the kind of acidic aqueous solution, aqueous solutions such as hydrofluoric acid, sulfuric acid, hydrochloric acid, and nitric acid can be used, and these may be used alone or in combination of two or more. The proportion of the acidic aqueous solution in the liquid containing one or more compounds represented by the general formula (1) soaking the composition containing carbon nanotubes is preferably 5 to 95% by weight, more preferably 20 to 90% by weight. And particularly preferably 30 to 80% by weight.

  In addition, when an alkaline aqueous solution having a pH of 8 or higher is used instead of water as a liquid for immersing a composition containing carbon nanotubes, the zeta potential of the composition containing carbon nanotubes can be adjusted, and aggregation of carbon nanotubes and solid catalysts can be prevented. The carbon nanotubes, carbon impurities, and solid catalyst can be recovered individually and efficiently. In particular, as described above, it is effective to use a liquid divided into at least two layers of an alkaline aqueous solution and an organic solvent. As a kind of alkaline aqueous solution, aqueous solution, such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, ammonia, can be used, for example. These may be used alone or in combination. The proportion of the alkaline aqueous solution in the liquid containing one or more compounds represented by the general formula (1) soaking the composition containing carbon nanotubes is preferably 5 to 95% by weight, more preferably 20 to 90% by weight. And particularly preferably 30 to 80% by weight.

  After soaking a composition containing carbon nanotubes in a liquid, before individually collecting a solution part containing a lot of carbon nanotubes and a solution part containing a lot of components other than carbon nanotubes contained in a composition containing carbon nanotubes In addition, when the agitation treatment is performed, the carbon nanotube, the carbon impurity, and the solid catalyst can be recovered individually and efficiently. The agitation process may be normal agitation using a stirrer or three-one motor and agitation blades, and structural or electronic defects are less likely to occur in the graphite layer of carbon nanotubes, and it is easy to scale up and is suitable for industrialization. There are advantages. Stirring that applies mechanical impact such as an attritor (preferably the rotation speed is 100 rpm or more) and a ball mill (ball impact is preferably 1 G or more) may be used.

  In addition, after the composition containing carbon nanotubes is immersed in a liquid, the solution part containing a lot of carbon nanotubes and the solution part containing a lot of components other than the carbon nanotubes contained in the composition containing carbon nanotubes are individually collected. If the ultrasonic treatment is performed before the carbon nanotube, the carbon nanotube, the carbon impurity, and the solid catalyst can be recovered individually and more efficiently. The higher the output of the ultrasonic treatment, the better. 10W or more, preferably 20W or more, more preferably 50W or more.

  Furthermore, after the composition containing carbon nanotubes is immersed in a liquid, the solution part containing a lot of carbon nanotubes and the solution part containing a lot of components other than the carbon nanotubes contained in the composition containing carbon nanotubes are individually collected. The carbon nanotube, the carbon impurity, and the solid catalyst can be recovered individually and efficiently by performing a centrifugal separation process. In the centrifugal separation treatment, a centrifugal acceleration of 500 (× g) or more, preferably 1000 (× g) or more is preferable because the purification efficiency of carbon nanotubes is improved.

  Furthermore, after making oxygen contact the composition containing a carbon nanotube at 200-800 degreeC, the refinement | purification efficiency of a carbon nanotube can be improved by immersing in a liquid. The solid catalyst used for the production of carbon nanotubes is present in a composition containing carbon nanotubes in a form whose surface is covered with carbon. In this state, oxygen is contacted at 200 to 800 ° C., carbon on the surface of the solid catalyst is removed, and the carbon nanotubes, carbon impurities, and solid catalyst can be recovered individually and efficiently by immersing them in a liquid. The temperature at which oxygen is brought into contact with the composition containing carbon nanotubes may be a temperature at which carbon covering the solid catalyst present in the composition can be removed without causing defects in the graphite layer of the carbon nanotubes. A temperature of 200 to 800 ° C., preferably 300 to 600 ° C., more preferably 350 to 500 ° C. is suitable because it can be recovered with a high yield. The time for contacting with oxygen can be arbitrarily selected within a range in which no defects occur in the graphite layer of the carbon nanotube.

  And the purification method of the composition containing a carbon nanotube as described above is obtained after purification with respect to the Raman G / D ratio (RI) and the exothermic peak temperature (TI) of the composition containing the carbon nanotube before purification. The composition containing carbon nanotubes, characterized in that the relationship between the Raman G / D ratio (RII) and the exothermic peak temperature (TII) of the carbon nanotubes with increased purity is RII ≧ RI and TII ≧ TI It becomes the purification method of the product. As described above, carbon nanotubes having a large Raman G / D ratio and a high exothermic peak temperature are excellent in heat resistance, mechanical strength, and conductivity. Such carbon nanotubes are used for negative electrodes for fuel cells and lithium secondary batteries, high-strength resins made of composite materials with resins and organic semiconductors, conductive resins, electromagnetic shielding materials, probes for scanning tunneling microscopes, field electron emission. It becomes a material suitable for uses such as a source, nanotweezers, adsorption material, medical nanocapsule, and MRI contrast agent.

  The method for producing carbon nanotubes used in the present invention is not particularly limited, and carbon nanotubes produced by various techniques as described above can be used. In particular, it is preferable to use carbon nanotubes produced by catalytic chemical vapor deposition. The reason for this will be described in detail below. To summarize the reason, carbon nanotubes can be manufactured at a low cost, and the cost is excellent. This is because the carbon nanotube has 2 to 5 layers and is excellent in characteristics.

  As a more specific method of the catalytic chemical vapor deposition method, a method in which a solid catalyst and a carbon-containing compound are brought into contact under a high temperature condition of 500 to 1200 ° C. is preferable. By this method, carbon nanotubes with few defects in the graphite layer can be produced at low cost.

  As a kind of catalyst metal which comprises a solid catalyst, the metal element which contains at least 1 or more types of the typical metal element chosen from the 1st group-the 16th group defined in the periodic table of elements, and a transition metal element can be mentioned. Among these, the use of at least one metal element selected from Co, Fe, and Ni as the catalyst metal is preferable because carbon nanotubes with few defects in the graphite layer can be synthesized with high yield.

  Further, the carbon-containing compound may be any of gas, liquid, and solid, but it is preferable that the carbon-containing compound is in a gaseous state under a high temperature condition of 500 to 1200 ° C. to come into contact with the solid catalyst because carbon nanotubes can be obtained with high yield. The type of carbon-containing compound is not particularly limited as long as it contains a carbon atom, but is usually carbon monoxide or a hydrocarbon compound, which may be aliphatic or aromatic, The bond may be a saturated bond or may contain an unsaturated bond. These may be used alone or in combination. As the aromatic hydrocarbon, for example, benzene, toluene, xylene, cumene, ethylbenzene, diethylbenzene, trimethylbenzene, naphthalene, phenanthrene, anthracene, or a mixture thereof can be used. As non-aromatic hydrocarbons, for example, methane, ethane, propane, butane, pentane, hexane, heptane, ethylene, propylene or acetylene, or a mixture thereof can be used. Hydrocarbons that contain oxygen, for example, alcohols such as methanol or ethanol, propanol, butanol, ketones such as acetone, and aldehydes such as formaldehyde or acetaldehyde, carboxylic acids such as trioxane, dioxane, dimethyl ether, diethyl ether, It may be an ester such as ethyl acetate or a mixture thereof.

  The carbon-containing compound may be a mixture with an inert gas such as nitrogen, argon, hydrogen, or helium, or may be used alone, but the reaction field where the carbon gas is supplied to the solid catalyst is an inert gas. Or in a vacuum atmosphere (reduced pressure) is preferred because carbon nanotubes can be obtained with good yield.

  The temperature at which the solid catalyst is brought into contact with the carbon-containing compound is 500 ° C to 1200 ° C, preferably 600 ° C to 1000 ° C. If the temperature is low, it will be difficult to obtain carbon nanotubes with good yield, and if the temperature is high, the material of the reactor used will be limited.

  The method for contacting the solid catalyst with the carbon-containing compound is not particularly limited. For example, a solid catalyst is held in a heating furnace, a carbon-containing compound is supplied into the heating furnace and contacted in the heating furnace, or a solid catalyst is flowed in the heating furnace, and a carbon-containing compound is supplied into the heating furnace. Then, there is a method of contacting in a heating furnace.

  Furthermore, in the carbon nanotube production method described above, it is preferable that a carbon nanotube with a controlled diameter can be produced by using a solid catalyst characterized in that a metal is supported on a solid support.

  The solid carrier may be organic or inorganic, but is preferably inorganic from the viewpoint of heat resistance. Examples of the inorganic solid support include silica, alumina, magnesium oxide, titanium oxide, silicate, diatomaceous earth, aluminosilicate, layered compound, zeolite, activated carbon, and graphite. Among these, an inorganic porous body capable of uniformly supporting the catalyst metal is preferable. Zeolite is particularly preferable, and the reason for this will be described later. This is because high-quality carbon nanotubes can be obtained with good yield.

  The supported amount of the catalyst metal of the solid support is preferably 0.1% by weight to 10.0% by weight, more preferably 0.5% by weight to 5.0% by weight. Is preferable because it can be selectively obtained.

  The method for supporting the catalytic metal on the solid support is not particularly limited. A solid support is impregnated in water or a non-aqueous solution (for example, ethanol solution) in which a metal salt to be supported is dissolved, sufficiently dispersed and mixed, dried, and then dried in air or an inert gas at a high temperature (300 to 600 ° C). ), The impregnation method capable of supporting the metal on the surface of the solid support, the amount of the aqueous solution of metal salt or the amount of alcohol is reduced as much as possible, the aqueous solution is adsorbed in the pores of the solid support, An equilibrium adsorption method in which an aqueous solution or alcohol is removed by filtration or the like, and an ion exchange method in which a metal cation and a cation of a solid support are exchanged in an aqueous solution are used. In addition, after a metal salt is supported on a solid support by an impregnation method or a parallel adsorption method, it is dried and heated at a high temperature (300 to 900 ° C.) in nitrogen, hydrogen, an inert gas or a mixed gas thereof, thereby A metal can be supported on the crystal surface. After loading the metal salt, it can be fired in air to form a metal oxide.

  The metal salt used in the above method is not particularly limited. Inorganic acid salts such as nitrates, acetates and sulfates, complex salts such as ethylenediaminetetraacetic acid complexes and acetylacetonate complexes, metal halides, organic complex salts and the like are used.

  In addition, the use of zeolite as a solid support can produce a composition containing carbon nanotubes, mainly composed of a single layer with few defects in the graphite layer or carbon nanotubes having a thin diameter of 2 to 5 layers. preferable.

  Zeolite is a crystalline inorganic oxide having a pore size of molecular size. The molecular size is a size range of molecules existing in the world, and generally means a range of about 0.2 to 2 nm. More specifically, it is a crystalline microporous material composed of crystalline silicate, crystalline aluminosilicate, crystalline metallosilicate, crystalline aluminophosphate, crystalline metalloaluminophosphate, or the like. There are no particular restrictions on the type of crystalline silicate, crystalline aluminosilicate, crystalline metallosilicate, crystalline aluminophosphate, crystalline metalloaluminophosphate, such as Atlas of Zeolite Structure Types (Meyer, Olson, Bauercher, Zeolites, 17 (1/2), 1996) (Atlas of Zeolite Structure types (WM Meier, DH Olson, Ch. Baerlocher, Zeolites, 17 (1/2), 1996)) Substances. Moreover, it is not limited to what is published in this literature, The zeolite which has the novel structure currently synthesized one after another is also included. Preferred structures are FAU type, MFI type, MOR type, and BEA type, which are easily available, but are not limited thereto.

  When the composition containing carbon nanotubes is characterized by containing a solid catalyst, not only the purity of the carbon nanotubes can be increased by the method of the present invention, but also the solid catalyst can be recovered and reused.

  In particular, when the solid catalyst is a form in which a metal is supported on a solid support, and the solid support is a zeolite, the obtained carbon nanotubes have few defects in the graphite layer, and the single-walled thin nanotube or the 2-5 carbon nanotubes with a small diameter Therefore, since the characteristics are excellent, the effect of reusing this solid catalyst is very large.

  As described above, the present invention recovers a solution part containing a large amount of a solid catalyst out of a solution part containing a large amount of components other than carbon nanotubes contained in a composition containing carbon nanotubes, and reuses the solid catalyst. It is related also to the purification method of the carbon nanotube characterized by this.

  By the purification method of the present invention, not only carbon nanotubes with improved impurities can be removed, but also carbon nanotubes having excellent heat resistance, mechanical strength, and conductivity can be obtained in high yield. Such carbon nanotubes are used for negative electrodes for fuel cells and lithium secondary batteries, high-strength resins made of composite materials with resins and organic semiconductors, conductive resins, electromagnetic shielding materials, probes for scanning tunneling microscopes, field electron emission. It becomes a material suitable for uses such as a source, nanotweezers, adsorption material, medical nanocapsule, and MRI contrast agent.

  Among carbon nanotubes, single-walled and 2-5 carbon nanotubes are considered to be excellent for the above applications, and especially 2-5 carbon nanotubes are superior in heat resistance compared to single-walled carbon nanotubes, making them ideal for the above applications. it is conceivable that. And it is especially effective to use the purification method of the composition containing the carbon nanotube by this invention for the composition containing a single-layer or a 2-5 layer carbon nanotube. As used herein, a composition containing single-walled or 2-5 carbon nanotubes means that a part of the carbon nanotubes contained in the composition is composed of single-walled carbon nanotubes or 2-5-walled carbon nanotubes. It may be. As a preferable state, the main component of the carbon nanotube contained in the composition is a single-walled carbon nanotube and / or a carbon nanotube having 2 to 5 layers. In the conventional purification method, single-walled or 2-5-walled carbon nanotubes have a small number of layers, and heat resistance, mechanical strength, and conductivity are remarkably lost, and the yield is also greatly reduced. Therefore, the method for purifying a composition containing carbon nanotubes according to the present invention is particularly effective for a composition containing single-walled or 2-5-layered carbon nanotubes. Single-walled or 2-5 carbon nanotubes obtained by the purification method according to the present invention are suitable for the above-mentioned applications, and 2-5 carbon nanotubes are most suitable.

  The present invention also relates to a carbon nanotube composition in which the liquid contains 0.01% by weight or more of carbon nanotubes and the bulk density of the carbon nanotubes in the liquid is 50 g / liter or less. Such a carbon nanotube composition is considered to be advantageous in that it is not troublesome to handle with powder as in the past, is excellent in workability, and has little influence on the human body due to dust. Furthermore, the bulk density of 50 g / liter is low in entanglement between carbon nanotubes, and is a high-strength resin or conductive resin made of a composite material of a fuel cell, a negative electrode material for a lithium secondary battery, a resin or an organic semiconductor. It is considered to be excellent in application characteristics as an electromagnetic shielding material, a scanning tunneling microscope probe, a field electron emission source, a nanotweezers material, an adsorbing material, a medical nanocapsule, and an MRI contrast medium. This means that the smaller the bulk density, the less the entanglement between the carbon nanotubes. In a state where the entanglement is extremely small, each carbon nanotube is dispersed in the liquid to form a colloidal solution. In the composition of the present invention, a part or all of the carbon nanotubes contained in the liquid may be in the form of a colloidal solution, but this is not necessarily required, and the carbon nanotubes may be precipitated or suspended. . The weight of the carbon nanotubes contained in the liquid is 0.01% by weight or more, preferably 0.01 to 5% by weight, more preferably 0.01 to 2.5% by weight. It is particularly preferably in the range of 0.01 to 1% by weight. The bulk density of the carbon nanotubes in the liquid is 50 g / liter or less, preferably 25 g / liter or less, more preferably 10 g / liter or less because the entanglement of the carbon nanotubes is small and the application characteristics are excellent. preferable. The bulk density of the carbon nanotubes in the liquid can be determined, for example, as follows. The composition is put into a graduated cylinder, allowed to stand for 7 days, and the numerical value (A) on the uppermost surface of the portion filled with carbon nanotubes is read. Next, the composition in the measuring cylinder is subjected to solid-liquid separation, and the carbon nanotubes recovered as a solid part are dried and weighed (B). By calculating (B) / (A), the bulk density of the carbon nanotubes in the liquid is obtained.

The present invention also relates to a carbon nanotube composition, wherein the liquid contained in the carbon nanotube composition is a liquid containing one or more compounds represented by the following general formula (1).
ClHmXn (1)
X = substituent containing any one of halogen, O, N, and S = 1 = representing an allowable integer with a valence of 1 or more m = 0 or n = 0 representing an allowed integer with a valence of 1 or more It represents an acceptable integer having a valence of 1 or more, except when n = m = 0. Such a carbon nanotube composition is preferable because it has less entanglement between carbon nanotubes and is excellent in the above-mentioned application characteristics. . In the general formula (1), l = 1 or more, m = 0 or more, n = 0 or more (except when n = m = 0), preferably l = 1 to 10, m = 0 to 22, n = 0 to 10 (except when n = m = 0), more preferably l = 1 to 6, m = 0 to 14, and n = 0 to 6 (except when n = m = 0) Range.

In addition, the compound represented by the general formula (1) is converted to X═OH.
l = representing a permissible integer of a valence of 4 or more m = representing a permissible integer of a valence of 4 or more, n = 1 representing a permissible integer of a valence of 1 or more, Since it becomes a carbon nanotube composition excellent in workability | operativity, it is preferable. In general formula (1), l = 1 or more, m = 3 or more, and n = 1 or more, preferably l = 1 to 10, m = 3 to 22, n = 1 to 10, and more preferably l = 1. -6, m = 3-14, n = 1-6.

Further, the compound represented by the general formula (1) is represented by l = 0 which represents an allowed integer having a valence of 1 or more, and m = 0 which represents an allowed integer of a valence of 5 or more.
It is preferable because the carbon nanotube composition is excellent in moisture absorption resistance and more excellent in workability. In the general formula (1), l = 5 or more, m = 5 or more, and n = 0, preferably 1 = 5 to 10, m = 5 to 22, n = 0, more preferably l = 5 to 6, It is the range of m = 5-14 and n = 0.

  Examples of the compound represented by the general formula (1) include inorganic compounds such as carbon disulfide and carbon tetrachloride, hydrocarbon compounds such as pentane, n-hexane, cyclohexane, isooctane, octane, benzene, toluene and xylene, chloroform 1,2-dichloroethane, 1,2-dibromoethane, trichloroethylene, tetrachloroethylene, chlorobenzene, bromobenzene, o-dichlorobenzene, methyl iodide, ethyl iodide, and the like, methanol, ethanol, 1-propanol, 2- Propanol, 2,2,2-trifluoroethanol, 1-butanol, 2-butanol, isobutyl alcohol, isopentyl alcohol, n-hexanol, cyclohexanol, ethylene glycol, propylene glycol, 2-methoxy Alcohols and phenols such as ethanol, 2-ethoxyethanol, phenol, benzyl alcohol, cresol, diethylene glycol, triethylene glycol, glycerin, diethyl ether, diisopropyl ether, tetrahydrofuran, tetrahydropyran, 1,4-dioxane, anisole, 1,2 -Ethers such as dimethoxyethane, diethylene glycol dimethyl ether, dicyclohexyl-18-crown-6, methyl carbitol, ethyl carbitol, aldehydes and ketones such as furfural, acetone, ethyl methyl ketone, cyclohexanone, formic acid, acetic acid, acetic anhydride, Trichloroacetic acid, trifluoroacetic acid, ethyl acetate, butyl acetate, ethylene carbonate, propylene carbonate, formamide, N-methylformua Acid, derivatives such as N, N-dimethylformamide, N-methylacetamide, N, N-dimethylacetamide, nitriles such as acetonitrile, propionitrile, succinonitrile, benzonitrile, nitromethane, nitrobenzene, ethylenediamine, pyridine, Examples thereof include nitro compounds and amines such as piperidine, morpholine, t-pentylamine, hexylamine and aniline, and sulfur compounds such as dimethyl sulfoxide and sulfolane.

  More preferable compounds include, for example, methanol, ethanol, 1-propanol, 2-propanol, 2,2,2-trifluoroethanol, 1-butanol, 2-butanol, isobutyl alcohol, isopentyl alcohol, n-hexanol, and cyclohexanol. And alcohol / phenols such as ethylene glycol, propylene glycol, 2-methoxyethanol, 2-ethoxyethanol, phenol, benzyl alcohol, cresol, diethylene glycol, triethylene glycol, and glycerin.

  More preferable compounds include hydrocarbon compounds such as pentane, n-hexane, cyclohexane, isooctane, octane, benzene, toluene and xylene.

  Particularly preferred compounds include, for example, pentanol, n-hexanol, cyclohexanol, n-hexane, and cyclohexane.

  The weight of the carbon nanotube composition contained in the liquid containing one or more compounds represented by the general formula (1) is 0.01% by weight or more, preferably in the range of 0.01 to 5% by weight, more Preferably it is the range of 0.01 to 2.5 weight%, Most preferably, it is the range of 0.01 to 1 weight%.

  Among these carbon nanotube compositions, it is preferable that they contain single-walled or 2-5 carbon nanotubes because of their excellent application characteristics. Particularly, 2-5 carbon nanotubes are more heat resistant than single-walled carbon nanotubes. It is considered to be optimal for application characteristics because of its superiority.

  Obtaining these carbon nanotube compositions by the method for purifying a composition containing carbon nanotubes of the present invention is preferable because the operation is easy and the entanglement between the carbon nanotubes is particularly small. That is, a composition containing carbon nanotubes is immersed in a liquid containing one or more compounds represented by the general formula (1), and a solution part containing a lot of carbon nanotubes and a solution part containing a lot of components other than carbon nanotubes are obtained. The high-purity carbon nanotubes collected individually and obtained at this time can be easily obtained because they already exist in a liquid containing one or more compounds represented by the general formula (1). The carbon nanotubes with increased purity have the property of being entangled with each other, but the carbon nanotubes with increased purity obtained by the purification method of the present invention are represented by the general formula (1) in all steps for increasing the purity of the carbon nanotubes. Since it is handled in a liquid containing one or more kinds of the compounds shown, there is little entanglement between the carbon nanotubes, and the application characteristics are excellent. By replacing the carbon nanotube composition present in the liquid containing one or more compounds represented by the general formula (1) thus obtained with a solvent, one or more compounds represented by the general formula (1) are contained. It is good also as a carbon nanotube composition which exists in the other liquid from the liquid.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples. However, the following examples are given for illustrative purposes and should not be used in any way as a limited interpretation of the present invention. .

<Reference Example 1>
(Support of metal salt on TS-1 zeolite)
Ferrous acetate (Aldrich) (0.1 g) and cobalt acetate tetrahydrate (Nacalai Tesque) (2.1 g) are added to ethanol (Nacalai Tesque) (400 ml) and suspended in an ultrasonic cleaner for 10 minutes. It became cloudy. To this suspension, 20.0 g of TS-1 zeolite (manufactured by NE Chemcat, silicon / titanium ratio 50) was added, treated with an ultrasonic cleaner for 10 minutes, ethanol was removed at a constant temperature of 60 ° C., and TS A solid catalyst having a metal salt supported on -1 type zeolite powder was obtained.

(Synthesis of a composition containing 2 to 5 carbon nanotubes)
4.0 g of the solid catalyst prepared in Reference Example 1 (supporting metal salt on TS-1 zeolite) was taken on quartz wool at the center of a quartz tube having an inner diameter of 64 mm, and argon gas was supplied at 600 cc / min. . The quartz tube was installed in an electric furnace, and the center temperature was heated to 800 ° C. (temperature rising time 30 minutes). After reaching 800 ° C., ultra high purity acetylene gas (manufactured by high pressure gas industry) is supplied at 5 cc / min for 30 minutes, then the supply of acetylene gas is stopped, the temperature is cooled to room temperature, and a composition containing carbon nanotubes Was taken out.

(Analysis of a composition containing 2 to 5 layers of carbon nanotubes)
When the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of a composition containing 2 to 5 layers of carbon nanotubes) was observed with a high-resolution transmission electron microscope, the carbon nanotubes were composed of clean graphite layers. Most of the carbon nanotubes have 2 to 5 layers. Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. Moreover, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm, and the average of the G / D ratio was calculated from 10 measurement spectra. . When heated at a rate of temperature increase of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 590 ° C.

<Reference Example 2>
(Support of metal salt on Y-type zeolite)
Add 0.2 g of ferrous acetate (Aldrich) and 2.1 g of cobalt acetate tetrahydrate (Nacalai Tesque) to 400 ml of ethanol (Nacalai Tesque) and suspend for 10 minutes with an ultrasonic cleaner. It became cloudy. To this suspension, 20.0 g of Y-type zeolite (manufactured by Tosoh Corporation, HSZ-390HUA) was added, treated with an ultrasonic cleaner for 10 minutes, ethanol was removed at a constant temperature of 60 ° C., and Y-type zeolite powder was obtained. A solid catalyst having a metal salt supported thereon was obtained.

(Synthesis of a composition containing single-walled carbon nanotubes)
On a quartz wool at the center of a quartz tube having an inner diameter of 64 mm, 4.0 g of the solid catalyst prepared in Reference Example 2 (supporting metal salt on Y-type zeolite) was taken, and argon gas was supplied at 200 cc / min. The quartz tube was installed in an electric furnace, and the center temperature was heated to 800 ° C. (temperature rising time 30 minutes). After reaching 800 ° C., the supply of argon gas was stopped. Ethanol vapor was supplied for 30 minutes while evacuating the inside of the quartz tube with a vacuum pump. At this time, the degree of vacuum inside the quartz tube was 5 Torr (0.7 KPa). The evacuation inside the quartz tube was stopped, and argon gas was supplied at 200 cc / min. The temperature was cooled to room temperature, and a composition containing carbon nanotubes was taken out.

(Analysis of compositions containing single-walled carbon nanotubes)
When the composition containing carbon nanotubes obtained in Reference Example 2 (synthesis of composition containing single-walled carbon nanotubes) was observed with a high-resolution transmission electron microscope, the carbon nanotubes were composed of a clean graphite layer. Most of them were single-walled carbon nanotubes. Many single-walled carbon nanotubes were observed in bundles. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. In addition, Raman spectroscopic measurement was performed at a laser wavelength of 633 nm using a Raman spectrophotometer INF-300 manufactured by HORIBA Joban Yvon, and the average of the G / D ratio was calculated from 10 measurement spectra. . When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 550 ° C.

<Reference Example 3>
(Support of metal salt on Y-type zeolite)
Add 1.2 g of ferrous acetate (Aldrich) and 2.1 g of cobalt acetate tetrahydrate (Nacalai Tesque) to 400 ml of ethanol (Nacalai Tesque) and suspend for 10 minutes with an ultrasonic cleaner. It became cloudy. To this suspension, 20.0 g of Y-type zeolite (HSZ-310NAA, manufactured by Tosoh Corporation) was added, treated with an ultrasonic cleaner for 10 minutes, ethanol was removed at a constant temperature of 60 ° C., and Y-type zeolite powder was obtained. A solid catalyst having a metal salt supported thereon was obtained.

(Synthesis of a composition containing multi-walled carbon nanotubes)
On a quartz wool at the center of a quartz tube having an inner diameter of 64 mm, 4.0 g of the solid catalyst prepared in Reference Example 3 (supporting metal salt on Y-type zeolite) was taken, and argon gas was supplied at 600 cc / min. The quartz tube was installed in an electric furnace, and the center temperature was heated to 600 ° C. (temperature rising time 30 minutes). After reaching 600 ° C., ultra high purity acetylene gas (manufactured by high pressure gas industry) is supplied at 10 cc / min for 30 minutes, then the supply of acetylene gas is stopped, the temperature is cooled to room temperature, and a composition containing carbon nanotubes Was taken out.

(Analysis of compositions containing multi-walled carbon nanotubes)
When the composition containing carbon nanotubes obtained in Reference Example 3 (synthesis of a composition containing multi-walled carbon nanotubes) was observed with a high-resolution transmission electron microscope, the carbon nanotubes were composed of a clean graphite layer. Most of them were multi-walled carbon nanotubes having 10 to 20 layers. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. Moreover, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm, and the average of the G / D ratio was calculated from 10 measurement spectra. . When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 600 ° C.

<Example 1>
(Purification of a composition containing 2 to 5 layers of carbon nanotubes (Pentanol, purification in one liquid system))
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of a composition containing 2 to 5 layers of carbon nanotubes) was heated to 400 ° C. (temperature raising time 40 minutes) in the air atmosphere. . After holding at 400 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of this carbon nanotube-containing composition was put into a beaker (for 300 ml) containing 200 ml of pentanol, stirred for 30 minutes with a stirrer, and an ultrasonic cleaner (manufactured by Yamato Chemical, BRANSON 3210, transmission frequency 47 KHz, After processing for 30 minutes at an output of 130 W), the mixture was allowed to stand for 30 minutes. 100 ml of the supernatant was collected with a pipette, and 100 ml of pentanol was added. Such a series of operations of stirring, sonication, standing, collecting supernatant and adding pentanol was repeated 10 times. The collected supernatant was filtered using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm) and separated into solid and liquid. Moreover, the precipitate part was collect | recovered and it filtered using the filter paper (Toyo Roshi Kaisha, Filter Paper No. 125mm), and separated into solid and liquid. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. When each solid substance was observed with a scanning electron microscope, TS-1 zeolite was mostly contained in the supernatant part and almost no carbon nanotubes were observed, and many carbon nanotubes were observed in the precipitated part. It can be seen that the solid catalyst could be recovered as the supernatant part, and the carbon nanotubes with increased purity were obtained as the precipitation part. Recovery rate of solid catalyst (amount of recovered solid catalyst / amount of solid catalyst contained in composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes)) × 100) was 40%. The amount of solid catalyst recovered and the amount of solid catalyst contained in the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes) Was heated to 800 ° C. (temperature rising time: 60 minutes) in an air atmosphere, held at 800 ° C. for 60 minutes, and calculated from the weight loss after burning out all the carbon materials.

(Analysis of solid matter in the precipitate)
When the solid matter of the precipitation part obtained in Example 1 (purification of the composition containing 2 to 5 layers of carbon nanotubes) was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed. Similar to the carbon nanotubes observed in (Analysis of compositions containing 2 to 5 layers of carbon nanotubes), most of the carbon nanotubes were composed of 2 to 5 layers of clean graphite layers. Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. In addition, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, and the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm. The average G / D ratio was calculated from 10 measurement spectra. The G / D ratio determined in (Analysis of a composition containing 2 to 5 layers of carbon nanotubes) was 3. When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 600 ° C. Even after the purification treatment, it can be expected that the graphite layer of the carbon nanotube has few defects, and it can be expected that the carbon nanotube is excellent in mechanical strength and conductivity.

<Example 2>
(Purification of a composition containing 2 to 5 layers of carbon nanotubes (Pentanol / ion-exchanged water, two-component purification))
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of a composition containing 2 to 5 layers of carbon nanotubes) was heated to 400 ° C. (temperature raising time 40 minutes) in the air atmosphere. . After holding at 400 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of this carbon nanotube-containing composition was put into a beaker (for 300 ml) containing 100 ml of pentanol and 100 ml of ion-exchanged water, stirred for 30 minutes with a stirrer, and an ultrasonic cleaner (manufactured by Yamato Chemical, BRANSON 3210). , Treated for 30 minutes at a transmission frequency of 47 KHz and an output of 130 W), transferred to a separatory funnel (for 250 ml) and allowed to stand for 30 minutes. The upper layer part (pentanol side) and the lower layer part (ion exchange water side) were separated and collected, and the collected upper layer part (pentanol side) was added to 100 ml of ion exchange water and charged into a beaker (for 300 ml). . Such a series of operations of adding ion-exchanged water to the agitation, sonication, standing, liquid separation, and collecting the upper layer (pentanol side) was repeated three times. The recovered lower layer (ion-exchanged water side) was filtered and solid-liquid separated using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm). Moreover, the upper layer part (pentanol side) was collect | recovered, it filtered using the filter paper (Toyo Rossi Kaisha, Filter Paper 2 125mm), and solid-liquid-separated. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. When each solid was observed with a scanning electron microscope, most of the TS-1 zeolite was present in the lower layer (on the ion-exchanged water side) and almost no carbon nanotubes, and many carbon nanotubes were observed in the upper layer (pentanol side). It was. It can be seen that the solid catalyst was recovered as the lower layer part (ion exchange water side), and the carbon nanotubes having increased purity were obtained as the upper layer part (pentanol side). Recovery rate of solid catalyst (amount of recovered solid catalyst / amount of solid catalyst contained in composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes)) × 100) was 60%. The amount of solid catalyst recovered and the amount of solid catalyst contained in the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes) Was heated to 800 ° C. (temperature rising time: 60 minutes) in an air atmosphere, held at 800 ° C. for 60 minutes, and calculated from the weight loss after burning out all the carbon materials.

(Analysis of solids in the upper layer (pentanol side))
When the solid matter in the upper layer part (pentanol side) obtained in Example 2 (purification of a composition containing 2 to 5 layers of carbon nanotubes) was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed. Similar to the carbon nanotubes observed in Reference Example 1 (analysis of a composition containing 2 to 5 layers of carbon nanotubes), most of the carbon nanotubes were composed of clean graphite layers with 2 to 5 layers. It was. Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. In addition, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, and the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm. The average G / D ratio was calculated from 10 measurement spectra. The G / D ratio determined in (Analysis of a composition containing 2 to 5 layers of carbon nanotubes) was 3. When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 600 ° C. Even after the purification treatment, it can be expected that the graphite layer of the carbon nanotube has few defects, and it can be expected that the carbon nanotube is excellent in mechanical strength and conductivity.

<Example 3>
(Purification of a composition containing 2 to 5 layers of carbon nanotubes (purification with n-hexane / ion-exchanged water two-component system, stirring treatment only))
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of a composition containing 2 to 5 layers of carbon nanotubes) was heated to 400 ° C. (temperature raising time 40 minutes) in the air atmosphere. . After holding at 400 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of the composition containing carbon nanotubes was put into a beaker (for 300 ml) containing 100 ml of n-hexane and 100 ml of ion-exchanged water, stirred for 30 minutes with a stirrer, and then put into a separating funnel (for 250 ml). Moved and left to stand for 30 minutes. The upper layer part (n-hexane side) and the lower layer part (ion-exchange water side) were separated and collected, and the collected upper layer part (n-hexane side) was added to 100 ml of ion-exchange water in a beaker (for 300 ml). I put it in. Such a series of operations of adding ion-exchanged water to the agitation, sonication, standing, liquid separation, and collecting the upper layer (n-hexane side) was repeated once and repeated three times. The recovered lower layer (ion-exchanged water side) was filtered and solid-liquid separated using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm). Moreover, the upper layer part (n-hexane side) was collect | recovered, and it filtered using the filter paper (Toyo Roshi Kaisha, Filter Paper 2 125mm), and carried out solid-liquid separation. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. When each solid was observed with a scanning electron microscope, TS-1 zeolite was mostly contained in the lower layer part (ion-exchange water side) and almost no carbon nanotubes, and many carbon nanotubes were found in the upper layer part (n-hexane side). Observed. It can be seen that the solid catalyst was recovered as the lower layer part (ion-exchanged water side), and the carbon nanotube with increased purity was obtained as the upper layer part (n-hexane side). Recovery rate of solid catalyst (amount of recovered solid catalyst / amount of solid catalyst contained in composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes)) × 100) was 60%. The amount of solid catalyst recovered and the amount of solid catalyst contained in the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes) Was heated to 800 ° C. (temperature rising time: 60 minutes) in an air atmosphere, held at 800 ° C. for 60 minutes, and calculated from the weight loss after burning out all the carbon materials.

(Analysis of solid in upper layer (n-hexane side))
When the solid matter in the upper layer (n-hexane side) obtained in Example 3 (purification of a composition containing 2 to 5 layers of carbon nanotubes) was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed. Similar to the carbon nanotubes observed in Reference Example 1 (analysis of a composition containing 2 to 5 layers of carbon nanotubes), most of the carbon nanotubes were composed of 2 to 5 layers of clean graphite layers. there were. Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. In addition, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, and the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm. The average G / D ratio was calculated from 10 measurement spectra. The G / D ratio determined in (Analysis of a composition containing 2 to 5 layers of carbon nanotubes) was 3. When heated at a rate of temperature increase of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 605 ° C. Even after the purification treatment, it can be expected that the graphite layer of the carbon nanotube has few defects, and it can be expected that the carbon nanotube is excellent in mechanical strength and conductivity.

<Example 4>
(Purification of composition containing carbon nanotubes of 2 to 5 layers (purification in cyclohexane / ion exchange water two-component system))
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of a composition containing 2 to 5 layers of carbon nanotubes) was heated to 400 ° C. (temperature raising time 40 minutes) in the air atmosphere. . After holding at 400 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of this carbon nanotube-containing composition was put into a beaker (for 300 ml) containing 100 ml of cyclohexane and 100 ml of ion-exchanged water, stirred for 30 minutes with a stirrer, and an ultrasonic cleaner (manufactured by Yamato Chemical, BRANSON 3210, After processing for 30 minutes at a transmission frequency of 47 KHz and an output of 130 W, it was transferred to a separating funnel (for 250 ml) and allowed to stand for 30 minutes. The upper layer part (cyclohexane side) and the lower layer part (ion exchange water side) were separated and collected, and the collected upper layer part (cyclohexane side) was added with 100 ml of ion exchange water and charged into a beaker (for 300 ml). Such a series of operations of adding ion-exchanged water to the agitation, sonication, standing, liquid separation, and collecting upper layer part (cyclohexane side) was repeated three times. The recovered lower layer (ion-exchanged water side) was filtered and solid-liquid separated using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm). Moreover, the upper layer part (cyclohexane side) was collect | recovered, and it filtered using the filter paper (Toyo Rossi Kaisha, Filter Paper No. 125mm), and carried out solid-liquid separation. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. At this time, the bulk density of the carbon nanotubes in cyclohexane in the upper layer part (cyclohexane side) was 10 g / liter (when 10 ml of the upper layer part (cyclohexane side) was transferred to the measuring cylinder, the liquid level of the carbon nanotubes was Was 1 ml, and the carbon nanotube contained therein was 10 mg). When each solid substance was observed with a scanning electron microscope, TS-1 zeolite was mostly contained in the lower layer (ion exchange water side) and almost no carbon nanotubes, and many carbon nanotubes were observed in the upper layer (cyclohexane side). It was. It can be seen that the solid catalyst could be recovered as the lower layer part (ion exchange water side), and the carbon nanotube with increased purity was obtained as the upper layer part (cyclohexane side). Recovery rate of solid catalyst (amount of recovered solid catalyst / amount of solid catalyst contained in composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes)) × 100) was 80%. The amount of solid catalyst recovered and the amount of solid catalyst contained in the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes) Was heated to 800 ° C. (temperature rising time: 60 minutes) in an air atmosphere, held at 800 ° C. for 60 minutes, and calculated from the weight loss after burning out all the carbon materials.

(Analysis of solids in the upper layer (cyclohexane side))
When the solid matter in the upper layer portion (cyclohexane side) obtained in Example 4 (purification of a composition containing 2 to 5 layers of carbon nanotubes) was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed, Similar to the carbon nanotubes observed in Reference Example 1 (analysis of a composition containing 2 to 5 layers of carbon nanotubes), most of the carbon nanotubes were composed of clean graphite layers with 2 to 5 layers. . Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. In addition, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, and the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm. The average G / D ratio was calculated from 10 measurement spectra. The G / D ratio determined in (Analysis of a composition containing 2 to 5 layers of carbon nanotubes) was 3. When heated at a rate of temperature increase of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 605 ° C. Even after the purification treatment, it can be expected that the graphite layer of the carbon nanotube has few defects, and it can be expected that the carbon nanotube is excellent in mechanical strength and conductivity.

<Example 5>
(Purification of a composition containing carbon nanotubes of 2 to 5 layers (refining with cyclohexane / ion exchange water two-component system, examination of firing temperature))
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes) was heated to 450 ° C. (temperature raising time: 40 minutes) in the air atmosphere. . After maintaining at 450 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of this carbon nanotube-containing composition was put into a beaker (for 300 ml) containing 100 ml of cyclohexane and 100 ml of ion-exchanged water, stirred for 30 minutes with a stirrer, and an ultrasonic cleaner (manufactured by Yamato Chemical, BRANSON 3210, After processing for 30 minutes at a transmission frequency of 47 KHz and an output of 130 W, it was transferred to a separating funnel (for 250 ml) and allowed to stand for 30 minutes. The upper layer part (cyclohexane side) and the lower layer part (ion exchange water side) were separated and collected, and the collected upper layer part (cyclohexane side) was added with 100 ml of ion exchange water and charged into a beaker (for 300 ml). Such a series of operations of adding ion-exchanged water to the agitation, sonication, standing, liquid separation, and collecting upper layer part (cyclohexane side) was repeated three times. The recovered lower layer (ion-exchanged water side) was filtered and solid-liquid separated using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm). Moreover, the upper layer part (cyclohexane side) was collect | recovered, and it filtered using the filter paper (Toyo Rossi Kaisha, Filter Paper No. 125mm), and carried out solid-liquid separation. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. When each solid substance was observed with a scanning electron microscope, TS-1 zeolite was mostly contained in the lower layer (ion exchange water side) and almost no carbon nanotubes, and many carbon nanotubes were observed in the upper layer (cyclohexane side). It was. It can be seen that the solid catalyst could be recovered as the lower layer part (ion exchange water side), and the carbon nanotube with increased purity was obtained as the upper layer part (cyclohexane side). Recovery rate of solid catalyst (amount of recovered solid catalyst / amount of solid catalyst contained in the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes)) × 100) was 85%. The amount of solid catalyst recovered and the amount of solid catalyst contained in the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes) Was heated to 800 ° C. (temperature rising time: 60 minutes) in an air atmosphere, held at 800 ° C. for 60 minutes, and calculated from the weight loss after burning out all the carbon materials.

(Analysis of solids in the upper layer (cyclohexane side))
When the solid matter of the upper layer part (cyclohexane side) obtained in Example 5 (purification of a composition containing 2 to 5 layers of carbon nanotubes) was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed, Similar to the carbon nanotubes observed in Reference Example 1 (analysis of a composition containing 2 to 5 layers of carbon nanotubes), most of the carbon nanotubes were composed of clean graphite layers with 2 to 5 layers. . Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. In addition, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, and the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm. The average G / D ratio was calculated from 10 measurement spectra. The G / D ratio determined in (Analysis of a composition containing 2 to 5 layers of carbon nanotubes) was 3. When heated at a rate of temperature increase of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 605 ° C. Even after the purification treatment, it can be expected that the graphite layer of the carbon nanotube has few defects, and it can be expected that the carbon nanotube is excellent in mechanical strength and conductivity.

<Example 6>
(Purification of a composition containing 2 to 5 layers of carbon nanotubes (Pentanol / ion-exchanged water, 2-component purification)
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of a composition containing 2 to 5 layers of carbon nanotubes) was heated to 400 ° C. (temperature raising time 40 minutes) in the air atmosphere. . After holding at 400 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of this carbon nanotube-containing composition was put into a beaker (for 300 ml) containing 100 ml of pentanol and 100 ml of ion-exchanged water, stirred for 30 minutes with a stirrer, and an ultrasonic cleaner (manufactured by Yamato Chemical, BRANSON 3210). , After processing for 30 minutes at a transmission frequency of 47 KHz and an output of 130 W), using a centrifuge (apparatus: KUBOTA KR-20000T, rotor: RA-3 50 ml × 8), rotating at 3000 rpm (about 1100 (× g)) ) After centrifuging under conditions of 1 hour, it was transferred to a separating funnel (for 250 ml) and allowed to stand for 30 minutes. The upper layer part (pentanol side) and the lower layer part (ion exchange water side) were separated and collected, and the collected upper layer part (pentanol side) was added to 100 ml of ion exchange water and charged into a beaker (for 300 ml). . Such a series of operations of adding ion-exchanged water to the upper layer part (pentanol side) such as stirring, sonication, centrifugation, standing, liquid separation, and recovery (pentanol side) was repeated three times. The recovered lower layer (ion-exchanged water side) was filtered and solid-liquid separated using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm). Moreover, the upper layer part (pentanol side) was collect | recovered, it filtered using the filter paper (Toyo Rossi Kaisha, Filter Paper 2 125mm), and solid-liquid-separated. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. When each solid was observed with a scanning electron microscope, most of the TS-1 zeolite was present in the lower layer (on the ion-exchanged water side) and almost no carbon nanotubes, and many carbon nanotubes were observed in the upper layer (pentanol side). It was. It can be seen that the solid catalyst was recovered as the lower layer part (ion exchange water side), and the carbon nanotubes having increased purity were obtained as the upper layer part (pentanol side). Recovery rate of solid catalyst (amount of recovered solid catalyst / amount of solid catalyst contained in composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes)) × 100) was 70%. The amount of solid catalyst recovered and the amount of solid catalyst contained in the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes) Was heated to 800 ° C. (temperature rising time: 60 minutes) in an air atmosphere, held at 800 ° C. for 60 minutes, and calculated from the weight loss after burning out all the carbon materials.

(Analysis of solids in the upper layer (pentanol side))
When the solid matter in the upper layer portion (pentanol side) obtained in Example 6 (Purification of composition containing 2 to 5 layers of carbon nanotubes) was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed. Similar to the carbon nanotubes observed in Reference Example 1 (analysis of a composition containing 2 to 5 layers of carbon nanotubes), most of the carbon nanotubes were composed of clean graphite layers with 2 to 5 layers. It was. Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. In addition, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, and the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm. The average G / D ratio was calculated from 10 measurement spectra. The G / D ratio determined in (Analysis of a composition containing 2 to 5 layers of carbon nanotubes) was 3. When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 600 ° C. Even after the purification treatment, it can be expected that the graphite layer of the carbon nanotube has few defects, and it can be expected that the carbon nanotube is excellent in mechanical strength and conductivity.

<Example 7>
(Purification of a composition containing 2 to 5 layers of carbon nanotubes (purification in a cyclohexane / NaCl aqueous solution)
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of a composition containing 2 to 5 layers of carbon nanotubes) was heated to 400 ° C. (temperature raising time 40 minutes) in the air atmosphere. . After holding at 400 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of the composition containing carbon nanotubes was put into a beaker (for 300 ml) containing 100 ml of cyclohexane and 100 ml of a 10% NaCl aqueous solution, stirred for 30 minutes with a stirrer, and an ultrasonic cleaner (manufactured by YAMATO Chemical). , BRANSON 3210, transmission frequency 47 KHz, output 130 W) for 30 minutes, then transferred to a separatory funnel (for 250 ml) and allowed to stand for 30 minutes. Separation of upper layer (cyclohexane side) and lower layer (NaCl aqueous solution side) (the interface between the upper layer (cyclohexane side) and lower layer (NaCl aqueous solution side) was clearly separated, so the workability of the liquid separation operation was improved), Each of the recovered upper layers (cyclohexane side) was added with 100 ml of a 10% NaCl aqueous solution and charged into a beaker (for 300 ml). Such a series of operations of adding a 10% NaCl aqueous solution to the upper layer (cyclohexane side) such stirring, sonication, standing, separation, and recovery was repeated once and repeated three times. The collected lower layer portion (NaCl aqueous solution side) was filtered using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm) and separated into solid and liquid. Moreover, the upper layer part (cyclohexane side) was collect | recovered, and it filtered using the filter paper (Toyo Rossi Kaisha, Filter Paper No. 125mm), and carried out solid-liquid separation. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. When each solid was observed with a scanning electron microscope, TS-1 zeolite was mostly contained in the lower layer (NaCl aqueous solution side) and almost no carbon nanotubes, and many carbon nanotubes were observed in the upper layer (cyclohexane side). . It can be seen that the solid catalyst was recovered as the lower layer part (NaCl aqueous solution side), and the carbon nanotubes having increased purity were obtained as the upper layer part (cyclohexane side). Recovery rate of solid catalyst (amount of recovered solid catalyst / amount of solid catalyst contained in composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes)) × 100) was 80%. The amount of solid catalyst recovered and the amount of solid catalyst contained in the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes) Was heated to 800 ° C. (temperature rising time: 60 minutes) in an air atmosphere, held at 800 ° C. for 60 minutes, and calculated from the weight loss after burning out all the carbon materials.

(Analysis of solids in the upper layer (cyclohexane side))
When the solid matter of the upper layer part (cyclohexane side) obtained in Example 7 (purification of a composition containing 2 to 5 layers of carbon nanotubes) was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed, Similar to the carbon nanotubes observed in Reference Example 1 (analysis of a composition containing 2 to 5 layers of carbon nanotubes), most of the carbon nanotubes were composed of clean graphite layers with 2 to 5 layers. . Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. In addition, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, and the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm. The average G / D ratio was calculated from 10 measurement spectra. The G / D ratio determined in (Analysis of a composition containing 2 to 5 layers of carbon nanotubes) was 3. When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 595 ° C. Even after the purification treatment, it can be expected that the graphite layer of the carbon nanotube has few defects, and it can be expected that the carbon nanotube is excellent in mechanical strength and conductivity.

<Example 8>
(Purification of a composition containing 2 to 5 layers of carbon nanotubes (cyclohexane / acidic aqueous solution)
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of a composition containing 2 to 5 layers of carbon nanotubes) was heated to 400 ° C. (temperature raising time 40 minutes) in the air atmosphere. . After holding at 400 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of the composition containing carbon nanotubes was put into a beaker (for 300 ml) containing 100 ml of cyclohexane and 100 ml of 10% HCl aqueous solution, stirred for 30 minutes with a stirrer, and an ultrasonic cleaner (manufactured by YAMATO CHEMICAL, After 30 minutes treatment with BRANSON 3210, transmission frequency 47 KHz, output 130 W), it was transferred to a separatory funnel (for 250 ml) and allowed to stand for 30 minutes. Separation of upper layer (cyclohexane side) and lower layer (HCl aqueous solution side) (Because the interface between the upper layer (cyclohexane side) and lower layer (HCl aqueous solution side) was clearly separated, the workability of the separation operation was improved), Each of the collected upper layers (cyclohexane side) was added to a beaker (for 300 ml) after adding 100 ml of 10% HCl aqueous solution. A series of operations such as stirring, sonication, standing, liquid separation, and adding a 10% aqueous HCl solution to the recovered upper layer (cyclohexane side) were repeated three times. The collected lower layer (HCl aqueous solution side) was filtered using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm) to separate into solid and liquid. Moreover, the upper layer part (cyclohexane side) was collect | recovered, and it filtered using the filter paper (Toyo Rossi Kaisha, Filter Paper No. 125mm), and carried out solid-liquid separation. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. When each solid was observed with a scanning electron microscope, TS-1 zeolite was mostly present in the lower layer (HCl aqueous solution side) and almost no carbon nanotubes, and many carbon nanotubes were observed in the upper layer (cyclohexane side). . It can be seen that the solid catalyst was recovered as the lower layer portion (HCl aqueous solution side), and carbon nanotubes with increased purity were obtained as the upper layer portion (cyclohexane side). Recovery rate of solid catalyst (amount of recovered solid catalyst / amount of solid catalyst contained in composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes)) × 100) was 80%. The amount of solid catalyst recovered and the amount of solid catalyst contained in the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes) Was heated to 800 ° C. (temperature rising time: 60 minutes) in an air atmosphere, held at 800 ° C. for 60 minutes, and calculated from the weight loss after burning out all the carbon materials.

(Analysis of solids in the upper layer (cyclohexane side))
When the solid matter in the upper layer portion (cyclohexane side) obtained in Example 8 (Purification of the composition containing 2 to 5 layers of carbon nanotubes) was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed, Similar to the carbon nanotubes observed in Reference Example 1 (analysis of a composition containing 2 to 5 layers of carbon nanotubes), most of the carbon nanotubes were composed of clean graphite layers with 2 to 5 layers. . Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. In addition, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, and the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm. The average G / D ratio was calculated from 10 measurement spectra. The G / D ratio determined in (Analysis of a composition containing 2 to 5 layers of carbon nanotubes) was 3. When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 600 ° C. Even after the purification treatment, it can be expected that the graphite layer of the carbon nanotube has few defects, and it can be expected that the carbon nanotube is excellent in mechanical strength and conductivity.

<Example 9>
(Purification of a composition containing carbon nanotubes of 2 to 5 layers (purification in cyclohexane / alkaline aqueous solution))
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of a composition containing 2 to 5 layers of carbon nanotubes) was heated to 400 ° C. (temperature raising time 40 minutes) in the air atmosphere. . After holding at 400 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of the composition containing carbon nanotubes was put into a beaker (for 300 ml) containing 100 ml of cyclohexane and 100 ml of 10% NaOH aqueous solution, stirred for 30 minutes with a stirrer, and an ultrasonic cleaner (manufactured by YAMATO CHEMICAL). , BRANSON 3210, transmission frequency 47 KHz, output 130 W) for 30 minutes, then transferred to a separatory funnel (for 250 ml) and allowed to stand for 30 minutes. The upper layer part (cyclohexane side) and the lower layer part (NaOH aqueous solution side) were separated and collected, and the collected upper layer part (cyclohexane side) was added to a beaker (for 300 ml) after adding 100 ml of 10% NaOH aqueous solution. . Such a series of operations of adding a 10% NaOH aqueous solution to the stirring (supersonic treatment), standing still, separating, and collecting the upper layer (cyclohexane side) was repeated three times. The collected lower layer portion (NaOH aqueous solution side) was filtered using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm) and separated into solid and liquid. Moreover, the upper layer part (cyclohexane side) was collect | recovered, and it filtered using the filter paper (Toyo Rossi Kaisha, Filter Paper No. 125mm), and carried out solid-liquid separation. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. When each solid was observed with a scanning electron microscope, TS-1 zeolite was mostly present in the lower layer (NaOH aqueous solution side) and almost no carbon nanotubes, and many carbon nanotubes were observed in the upper layer (cyclohexane side). . It can be seen that the solid catalyst was recovered as the lower layer part (NaOH aqueous solution side), and the carbon nanotubes having increased purity were obtained as the upper layer part (cyclohexane side). Recovery rate of solid catalyst (amount of recovered solid catalyst / amount of solid catalyst contained in the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes)) × 100) was 85%. The amount of solid catalyst recovered and the amount of solid catalyst contained in the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of composition containing 2 to 5 layers of carbon nanotubes) Was heated to 800 ° C. (temperature rising time: 60 minutes) in an air atmosphere, held at 800 ° C. for 60 minutes, and calculated from the weight loss after burning out all the carbon materials.

(Analysis of solids in the upper layer (cyclohexane side))
When the solid matter in the upper layer portion (cyclohexane side) obtained in Example 8 (Purification of the composition containing 2 to 5 layers of carbon nanotubes) was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed, Similar to the carbon nanotubes observed in Reference Example 1 (analysis of a composition containing 2 to 5 layers of carbon nanotubes), most of the carbon nanotubes were composed of clean graphite layers with 2 to 5 layers. . Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. Moreover, when the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm, and the average G / D ratio was calculated from 10 measurement spectra. The G / D ratio determined in (Analysis of composition containing 2 to 5 layers of carbon nanotubes) was 3. When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 610 ° C. Even after the purification treatment, it can be expected that the graphite layer of the carbon nanotube has few defects, and it can be expected that the carbon nanotube is excellent in mechanical strength and conductivity.

<Example 10>
(Purification of a composition containing carbon nanotubes of 2 to 5 layers (purification with cyclohexane / ion exchange water two-component system hydrofluoric acid treatment))
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of a composition containing 2 to 5 layers of carbon nanotubes) was heated to 400 ° C. (temperature raising time 40 minutes) in the air atmosphere. . After holding at 400 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of this carbon nanotube-containing composition was put into a beaker (for 300 ml) containing 100 ml of cyclohexane and 100 ml of ion-exchanged water, stirred for 30 minutes with a stirrer, and an ultrasonic cleaner (manufactured by Yamato Chemical, BRANSON 3210, After processing for 30 minutes at a transmission frequency of 47 KHz and an output of 130 W, it was transferred to a separating funnel (for 250 ml) and allowed to stand for 30 minutes. The upper layer part (cyclohexane side) and the lower layer part (ion exchange water side) were separated and collected, and the collected upper layer part (cyclohexane side) was added with 100 ml of ion exchange water and charged into a beaker (for 300 ml). Such a series of operations of adding ion-exchanged water to the agitation, sonication, standing, liquid separation, and collecting upper layer part (cyclohexane side) was repeated three times. The recovered lower layer (ion-exchanged water side) was filtered and solid-liquid separated using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm). Moreover, the upper layer part (cyclohexane side) was collect | recovered, and it filtered using the filter paper (Toyo Rossi Kaisha, Filter Paper No. 125mm), and carried out solid-liquid separation. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. When each solid substance was observed with a scanning electron microscope, TS-1 zeolite was mostly contained in the lower layer (ion exchange water side) and almost no carbon nanotubes, and many carbon nanotubes were observed in the upper layer (cyclohexane side). It was. Furthermore, the solid matter collected from the upper layer part (cyclohexane side) was put into 100 ml of a hydrofluoric acid aqueous solution having a concentration of 0.8 mol / liter, and then stirred for 1 hour while maintaining at room temperature. Thereafter, the mixture was filtered using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm) and separated into solid and liquid. The solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to collect the solid matter.

(Analysis of solids after treatment with hydrofluoric acid solution)
When the solid after the hydrofluoric acid aqueous solution treatment of Example 10 was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed, and the composition of Reference Example 1 (a composition containing 2 to 5 layers of carbon nanotubes) was observed. Similar to the carbon nanotubes observed in (Analysis), most of the carbon nanotubes were composed of 2 to 5 layers composed of clean graphite layers. Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. As a result of elemental analysis using an EDS attached to a scanning microscope (JSM-6301F) manufactured by JEOL Ltd., silicon was less than 1% by weight and metal (iron, cobalt) was 1% by weight with respect to 100% by weight of carbon. % Or less. In addition, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, and the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm. The average G / D ratio was calculated from 10 measurement spectra. The G / D ratio determined in (Analysis of a composition containing 2 to 5 layers of carbon nanotubes) was 3. When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 600 ° C. Even after the purification treatment, it can be expected that the graphite layer of the carbon nanotube has few defects, and it can be expected that the carbon nanotube is excellent in mechanical strength and conductivity.

<Example 11>
(Purification of a composition containing single-walled carbon nanotubes (refining with cyclohexane / ion exchange water two-component system hydrofluoric acid treatment))
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 2 (synthesis of composition containing single-walled carbon nanotubes) was heated to 400 ° C. (temperature raising time: 40 minutes) in an air atmosphere. After holding at 400 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of this carbon nanotube-containing composition was put into a beaker (for 300 ml) containing 100 ml of cyclohexane and 100 ml of ion-exchanged water, stirred for 30 minutes with a stirrer, and an ultrasonic cleaner (manufactured by Yamato Chemical, BRANSON 3210, After processing for 30 minutes at a transmission frequency of 47 KHz and an output of 130 W, it was transferred to a separating funnel (for 250 ml) and allowed to stand for 30 minutes. The upper layer part (cyclohexane side) and the lower layer part (ion exchange water side) were separated and collected, and the collected upper layer part (cyclohexane side) was added with 100 ml of ion exchange water and charged into a beaker (for 300 ml). Such a series of operations of adding ion-exchanged water to the agitation, sonication, standing, liquid separation, and collecting upper layer part (cyclohexane side) was repeated three times. The recovered lower layer (ion-exchanged water side) was filtered and solid-liquid separated using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm). Moreover, the upper layer part (cyclohexane side) was collect | recovered, and it filtered using the filter paper (Toyo Rossi Kaisha, Filter Paper No. 125mm), and carried out solid-liquid separation. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. When each solid was observed with a scanning electron microscope, most of the Y-type zeolite was present in the lower layer (on the ion-exchanged water side) and almost no carbon nanotubes, and many carbon nanotubes were observed in the upper layer (on the cyclohexane side). . It can be seen that the solid catalyst could be recovered as the lower layer part (ion exchange water side), and the carbon nanotube with increased purity was obtained as the upper layer part (cyclohexane side). Recovery rate of solid catalyst (amount of recovered solid catalyst / amount of solid catalyst contained in composition containing carbon nanotubes obtained in (Synthesis of composition containing single-walled carbon nanotubes) in Reference Example 2 × 100) Was 95%. The amount of the solid catalyst recovered and the amount of the solid catalyst contained in the composition containing carbon nanotubes obtained in Reference Example 2 (synthesis of the composition containing single-walled carbon nanotubes) were determined in the atmosphere. And heated to 800 ° C. (temperature rising time 60 minutes), held at 800 ° C. for 60 minutes, and calculated from the weight loss after burning out all the carbon materials. Furthermore, the solid matter recovered from the upper layer part (cyclohexane side) was put into 100 ml of a hydrofluoric acid aqueous solution having a concentration of 0.2 mol / liter, and then stirred for 1 hour while maintaining at room temperature. Thereafter, the mixture was filtered using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm) and separated into solid and liquid. The solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to collect the solid matter.

(Analysis of solids after treatment with hydrofluoric acid solution)
When the solid matter after the hydrofluoric acid aqueous solution treatment of Example 11 was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed, and in Reference Example 2 (analysis of composition containing single-walled carbon nanotubes) Similar to the observed carbon nanotubes, the carbon nanotubes were composed of a clean graphite layer, and the single-walled carbon nanotubes were mostly. Many single-walled carbon nanotubes were observed in bundles. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. As a result of elemental analysis using an EDS attached to a scanning microscope (JSM-6301F) manufactured by JEOL Ltd., silicon was less than 1% by weight and metal (iron, cobalt) was 1% by weight with respect to 100% by weight of carbon. % Or less. Moreover, when the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm, and the average G / D ratio was calculated from 10 measurement spectra. It was 35 like the G / D ratio calculated | required by (analysis of the composition containing a single wall carbon nanotube). When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 560 ° C. Even after the purification treatment, it can be expected that the graphite layer of the carbon nanotube has few defects, and it can be expected that the carbon nanotube is excellent in mechanical strength and conductivity.

<Example 12>
(Purification of a composition containing multi-walled carbon nanotubes (Cyclohexane / ion-exchanged water two-component purification hydrofluoric acid treatment))
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 3 (synthesis of composition containing multi-walled carbon nanotubes) was heated to 500 ° C. (temperature raising time: 40 minutes) in an air atmosphere. After holding at 500 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of this carbon nanotube-containing composition was put into a beaker (for 300 ml) containing 100 ml of cyclohexane and 100 ml of ion-exchanged water, stirred for 30 minutes with a stirrer, and an ultrasonic cleaner (manufactured by Yamato Chemical, BRANSON 3210, After processing for 30 minutes at a transmission frequency of 47 KHz and an output of 130 W, it was transferred to a separating funnel (for 250 ml) and allowed to stand for 30 minutes. The upper layer part (cyclohexane side) and the lower layer part (ion exchange water side) were separated and collected, and the collected upper layer part (cyclohexane side) was added with 100 ml of ion exchange water and charged into a beaker (for 300 ml). Such a series of operations of adding ion-exchanged water to the agitation, sonication, standing, liquid separation, and collecting upper layer part (cyclohexane side) was repeated three times. The recovered lower layer (ion-exchanged water side) was filtered and solid-liquid separated using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm). Moreover, the upper layer part (cyclohexane side) was collect | recovered, and it filtered using the filter paper (Toyo Rossi Kaisha, Filter Paper No. 125mm), and carried out solid-liquid separation. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. When each solid was observed with a scanning electron microscope, most of the Y-type zeolite was present in the lower layer (on the ion-exchanged water side) and almost no carbon nanotubes, and many carbon nanotubes were observed in the upper layer (on the cyclohexane side). . It can be seen that the solid catalyst could be recovered as the lower layer part (ion exchange water side), and the carbon nanotube with increased purity was obtained as the upper layer part (cyclohexane side). Recovery rate of solid catalyst (amount of recovered solid catalyst / amount of solid catalyst contained in the composition containing carbon nanotubes obtained in (Synthesis of composition containing multi-walled carbon nanotubes) in Reference Example 3 × 100) is 70%. The amount of the solid catalyst recovered and the amount of the solid catalyst contained in the composition containing the carbon nanotubes obtained in Reference Example 3 (synthesis of the composition containing multi-walled carbon nanotubes) were determined in the atmosphere of the sample. And heated to 800 ° C. (temperature rising time 60 minutes), held at 800 ° C. for 60 minutes, and calculated from the weight loss after burning out all the carbon materials. Furthermore, the solid matter collected from the upper layer part (cyclohexane side) was put into 100 ml of a hydrofluoric acid aqueous solution having a concentration of 1.2 mol / liter, and then stirred for 1 hour while maintaining at room temperature. Thereafter, the mixture was filtered using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm) and separated into solid and liquid. The solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to collect the solid matter.

(Analysis of solids after treatment with hydrofluoric acid solution)
When the solid matter after the hydrofluoric acid aqueous solution treatment of Example 12 was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed, and were observed in Reference Example 3 (analysis of a composition containing multi-walled carbon nanotubes). Like the carbon nanotubes, the carbon nanotubes were composed of a clean graphite layer, and most of them were multi-walled carbon nanotubes having 10 to 20 layers. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. As a result of elemental analysis using an EDS attached to a scanning microscope (JSM-6301F) manufactured by JEOL Ltd., silicon was less than 1% by weight and metal (iron, cobalt) was 1% by weight with respect to 100% by weight of carbon. % Or less. Moreover, when the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm, and the average G / D ratio was calculated from 10 measurement spectra. The G / D ratio determined in (Analysis of composition containing multi-walled carbon nanotubes) was 1. When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 600 ° C. Even after the purification treatment, it can be expected that the graphite layer of the carbon nanotube has few defects, and it can be expected that the carbon nanotube is excellent in mechanical strength and conductivity.

<Example 13>
(Synthesis of a composition containing 2 to 5 carbon nanotubes, reuse of a solid catalyst)
On the quartz wool at the center of a quartz tube having an inner diameter of 64 mm, 4.0 g of the solid material in the lower layer (ion-exchanged water side) recovered by the method of Example 4 was taken, and argon gas was supplied at 600 cc / min. The quartz tube was installed in an electric furnace, and the center temperature was heated to 800 ° C. (temperature rising time 30 minutes). After reaching 800 ° C., ultra high purity acetylene gas (manufactured by high pressure gas industry) is supplied at 5 cc / min for 30 minutes, then the supply of acetylene gas is stopped, the temperature is cooled to room temperature, and a composition containing carbon nanotubes Was taken out.

(Analysis of a composition containing 2 to 5 layers of carbon nanotubes)
The composition containing carbon nanotubes obtained in Example 13 (synthesis of a composition containing 2 to 5 layers of carbon nanotubes) was observed with a high-resolution transmission electron microscope. (Analysis of composition containing carbon nanotubes), the carbon nanotubes were composed of a clean graphite layer, and most of the carbon nanotubes were 2 to 5 in number. Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. Moreover, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm, and the average of the G / D ratio was calculated from 10 measurement spectra. . When heated at a rate of temperature increase of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 590 ° C. It can be seen that the solid catalyst recovered by the method of the present invention can be reused.

<Example 14>
(Synthesis of compositions containing single-walled carbon nanotubes, reuse of solid catalyst)
On the quartz wool at the center of a quartz tube having an inner diameter of 64 mm, 4.0 g of the solid material in the lower layer (ion-exchanged water side) recovered by the method of Example 11 was taken, and argon gas was supplied at 200 cc / min. The quartz tube was installed in an electric furnace, and the center temperature was heated to 800 ° C. (temperature rising time 30 minutes). After reaching 800 ° C., the supply of argon gas was stopped. Ethanol vapor was supplied for 30 minutes while evacuating the inside of the quartz tube with a vacuum pump. At this time, the degree of vacuum inside the quartz tube was 5 Torr (0.7 KPa). The evacuation inside the quartz tube was stopped, and argon gas was supplied at 200 cc / min. The temperature was cooled to room temperature, and a composition containing carbon nanotubes was taken out.

(Analysis of compositions containing single-walled carbon nanotubes)
When the composition containing carbon nanotubes obtained in Example 14 (synthesis of composition containing single-walled carbon nanotubes) was observed with a high-resolution transmission electron microscope, the composition containing single-walled carbon nanotubes in Reference Example 2 (containing single-walled carbon nanotubes) The carbon nanotubes were composed of a clean graphite layer, and the single-walled carbon nanotubes were mostly the same as the carbon nanotubes observed in the analysis of the composition. Many single-walled carbon nanotubes were observed in bundles. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. In addition, Raman spectroscopic measurement was performed at a laser wavelength of 633 nm using a Raman spectrophotometer INF-300 manufactured by HORIBA Joban Yvon, and the average of the G / D ratio was calculated from 10 measurement spectra. . When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 550 ° C. It can be seen that the solid catalyst recovered by the method of the present invention can be reused.

<Example 15>
(Synthesis of composition containing multi-walled carbon nanotubes, reuse of solid catalyst)
On the quartz wool at the center of the quartz tube having an inner diameter of 64 mm, 4.0 g of the solid material in the lower layer (ion-exchanged water side) recovered by the method of Example 12 was taken, and argon gas was supplied at 600 cc / min. The quartz tube was installed in an electric furnace, and the center temperature was heated to 600 ° C. (temperature rising time 30 minutes). After reaching 600 ° C., ultra high purity acetylene gas (manufactured by high pressure gas industry) is supplied at 10 cc / min for 30 minutes, then the supply of acetylene gas is stopped, the temperature is cooled to room temperature, and a composition containing carbon nanotubes Was taken out.

(Analysis of compositions containing multi-walled carbon nanotubes)
When the composition containing carbon nanotubes obtained in Example 15 (synthesis of a composition containing multi-walled carbon nanotubes) was observed with a high-resolution transmission electron microscope, the composition of Reference Example 3 (composition containing multi-walled carbon nanotubes) was observed. Similar to the carbon nanotubes observed in the analysis of the product, the carbon nanotubes were composed of a clean graphite layer, and most of them were multi-walled carbon nanotubes having 10 to 20 layers. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. Moreover, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm, and the average of the G / D ratio was calculated from 10 measurement spectra. . When heated at a heating rate of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 600 ° C. It can be seen that the solid catalyst recovered by the method of the present invention can be reused.

<Example 1 6>
(Purification of compositions containing single-walled carbon nanotubes)
2.0 g of the composition containing single-walled carbon nanotubes synthesized by the arc discharge method is put into a beaker (for 300 ml) containing 100 ml of cyclohexane and 100 ml of ion-exchanged water, stirred for 30 minutes with a stirrer, and subjected to ultrasonic cleaning. The sample was treated with a vessel (manufactured by Yamato Chemical, BRANSON 3210, transmission frequency 47 KHz, output 130 W) for 30 minutes, then transferred to a separatory funnel (for 250 ml) and allowed to stand for 30 minutes. The upper layer part (cyclohexane side) and the lower layer part (ion exchange water side) were separated and collected, and the collected upper layer part (cyclohexane side) was added with 100 ml of ion exchange water and charged into a beaker (for 300 ml). A series of operations for adding ion-exchanged water to the upper layer part (cyclohexane side) such stirring, sonication, standing, liquid separation, and recovery was repeated once and repeated 10 times. The recovered lower layer (ion-exchanged water side) was filtered and solid-liquid separated using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm). Moreover, the upper layer part (cyclohexane side) was collect | recovered, it filtered using the filter paper (Toyo Rossi Kaisha, Filter Paper No. 125mm), and solid-liquid-separated. In each case, the solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to recover the solid matter. When each solid was observed with a scanning electron microscope, there were almost no carbon nanotubes in the lower layer (on the ion-exchanged water side), and many fine particles and films were observed, and in the upper layer (the cyclohexane side) Many carbon nanotubes were observed . It can be seen that carbon nanotubes having improved purity as the upper layer portion (cyclohexane side) was obtained.

<Comparative Example 1>
(Purification of a composition containing 2 to 5 layers of carbon nanotubes)
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 1 (synthesis of a composition containing 2 to 5 layers of carbon nanotubes) was heated to 400 ° C. (temperature raising time 40 minutes) in the air atmosphere. . After holding at 400 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of the composition containing carbon nanotubes was put into 100 ml of a hydrofluoric acid aqueous solution having a concentration of 5 mol / liter, and then stirred for 1 hour while being kept at room temperature. Thereafter, the mixture was filtered using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm) and separated into solid and liquid. The solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to collect the solid matter.

(Analysis of solids after treatment with hydrofluoric acid solution)
When the solid matter after the hydrofluoric acid aqueous solution treatment of Comparative Example 1 was observed with a high-resolution transmission electron microscope, carbon nanotubes were observed and the number of layers composed of relatively clean graphite layers was 2 to 5 carbon. Most were nanotubes. Single-walled carbon nanotubes were also observed. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. As a result of elemental analysis using an EDS attached to a scanning microscope (JSM-6301F) manufactured by JEOL Ltd., silicon was less than 1% by weight and metal (iron, cobalt) was 3% with respect to 100% by weight of carbon. %Met. Moreover, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, and the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm. . When heated at a rate of temperature increase of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 580 ° C.

<Comparative example 2>
(Purification of a composition containing single-walled carbon nanotubes)
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 2 (synthesis of composition containing single-walled carbon nanotubes) was heated to 400 ° C. (temperature raising time: 40 minutes) in an air atmosphere. After holding at 400 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of the composition containing carbon nanotubes was put into 100 ml of a hydrofluoric acid aqueous solution having a concentration of 5 mol / liter, and then stirred for 1 hour while being kept at room temperature. Thereafter, the mixture was filtered using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm) and separated into solid and liquid. The solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to collect the solid matter.

(Analysis of solids after treatment with hydrofluoric acid solution)
When the solid matter after the hydrofluoric acid aqueous solution treatment of Comparative Example 2 was observed with a high-resolution transmission electron microscope, the carbon nanotubes were composed of a relatively clean graphite layer, and the single-walled carbon nanotubes were mostly. . Many single-walled carbon nanotubes were observed in bundles. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. As a result of elemental analysis using an EDS attached to a scanning microscope (JSM-6301F) manufactured by JEOL Ltd., silicon was 2% by weight and metal (iron, cobalt) was 2% by weight with respect to 100% by weight of carbon. Met. Moreover, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm, and the average of the G / D ratio was calculated from 10 measurement spectra. . When heated at a rate of temperature increase of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 400 ° C.

<Comparative Example 3>
(Purification of a composition containing multi-walled carbon nanotubes)
2.5 g of the composition containing carbon nanotubes obtained in Reference Example 3 (synthesis of composition containing multi-walled carbon nanotubes) was heated to 500 ° C. (temperature raising time: 40 minutes) in an air atmosphere. After holding at 500 ° C. for 60 minutes, it was cooled to room temperature (temperature drop time 60 minutes). 2.0 g of the composition containing carbon nanotubes was put into 100 ml of a hydrofluoric acid aqueous solution having a concentration of 5 mol / liter, and then stirred for 1 hour while being kept at room temperature. Thereafter, the mixture was filtered using a filter paper (Toyo Roshi Kaisha, Filter Paper No. 125 mm) and separated into solid and liquid. The solid matter on the filter paper was washed with 500 ml of purified water and then dried with a drier set at 60 ° C. to collect the solid matter.

(Analysis of solids after treatment with hydrofluoric acid solution)
When the solid after the hydrofluoric acid aqueous solution treatment of Comparative Example 3 was observed with a high-resolution transmission electron microscope, the carbon nanotubes were composed of a relatively clean graphite layer, and the number of layers was 10-20. Mostly carbon nanotubes. Carbon impurities other than carbon nanotubes (fullerene, nanoparticles, amorphous carbon, etc.) were hardly observed. As a result of elemental analysis using an EDS attached to a scanning microscope (JSM-6301F) manufactured by JEOL Ltd., silicon was less than 1% by weight and metal (iron, cobalt) was 2% with respect to 100% by weight of carbon. %Met. Moreover, the Raman spectroscopic measurement apparatus INF-300 manufactured by Horiba Joban Yvon Co., Ltd. was used, the Raman spectroscopic measurement was performed at a laser wavelength of 633 nm, and the average of the G / D ratio was calculated from 10 measurement spectra. . When heated at a rate of temperature increase of 10 ° C./min in an air stream of 30 ml / min with a thermal analyzer DTG-50 manufactured by Shimadzu Corporation, the exothermic peak temperature was 590 ° C.

  According to the present invention, carbon nanotubes excellent in heat resistance, mechanical strength, and conductivity can be obtained with high purity. Such carbon nanotubes are used for negative electrodes for fuel cells and lithium secondary batteries, high-strength resins composed of composite materials with resins and organic semiconductors, conductive resins, materials for electromagnetic shielding materials, probes for scanning tunneling microscopes, electric fields Excellent application characteristics as electron emission source, nanotweezer material, adsorbent material, medical nanocapsule, MRI contrast agent material. In addition, since the solid catalyst can be recovered and reused, there is little waste and it can cope with environmental problems. Furthermore, the carbon nanotubes dispersed in the liquid are excellent in application characteristics because there are few entanglements between the carbon nanotubes, and are excellent in workability without the trouble of handling dust. These excellent characteristics can be applied.

Claims (10)

A carbon nanotube-containing composition is immersed in a liquid divided into two or more layers, and a solution portion containing a large amount of carbon nanotubes and a solution portion containing a large amount of components other than carbon nanotubes are individually collected to obtain carbon. A method for purifying a composition containing carbon nanotubes, characterized by increasing the purity of the nanotubes, wherein at least one of the two or more layers is a liquid selected from the following (A): The method of claim 1, wherein the layer comprises an organic solvent having an SP value of 13.4 or less.
(A) Water, a sodium chloride aqueous solution having a sodium chloride concentration of 0.1 wt% or more, an acidic aqueous solution having a pH of 6 or less, and an alkaline aqueous solution having a pH of 8 or more. The method for purifying a composition containing carbon nanotubes according to claim 1, wherein the SP value of the organic solvent is 8.4 or less. Carbon according to claim 1, characterized in that the organic solvent is selected from pentane, n-hexane, cyclohexane, isooctane, octane, benzene, toluene, xylene, pentanol, n-hexanol, cyclohexanol. A method for purifying a composition containing nanotubes. Before individually collecting the solution part containing a lot of carbon nanotubes and the solution part containing a lot of components other than carbon nanotubes, at least one treatment selected from a stirring process, an ultrasonic treatment and a centrifugal separation process is performed. The purification method of the composition containing the carbon nanotube of any one of Claims 1-3. The composition containing carbon nanotubes according to any one of claims 1 to 4, wherein the composition containing carbon nanotubes is contacted with oxygen at 200 to 800 ° C and then immersed in a liquid. Purification method. The purification method of the composition containing the carbon nanotube of any one of Claims 1-5 which satisfy | fills the following requirements (1) and (2).
(1) a maximum peak intensity in the range of 1550～1650Cm ^-1 in spectrum obtained by measurement of the resonance Raman scattering measurement method G, a maximum peak intensity in the range of 1300～1400Cm ^-1 is D The relationship of the Raman G / D ratio (RII) of the carbon nanotubes with increased purity after purification to the Raman G / D ratio (RI) of the composition containing the carbon nanotubes before purification is RII ≧ RI.
(2) When a thermal analysis is performed up to 900 ° C. by raising the temperature at 10 ° C./min in the air atmosphere, the composition containing a carbon nanotube before purification having an exothermic peak in the temperature range of 300 to 900 ° C. The relationship between the exothermic peak temperature (TI) and the exothermic peak temperature (TII) of the carbon nanotube with increased purity after purification is TII ≧ TI. The method for purifying a composition containing carbon nanotubes according to any one of claims 1 to 6 , wherein the composition containing carbon nanotubes contains a solid catalyst. 8. The purification of a composition containing carbon nanotubes according to claim 7 , wherein a solution part containing a large amount of solid catalyst is recovered from a solution part containing a large amount of components other than carbon nanotubes, and the solid catalyst is reused. Method. The method for purifying a composition containing carbon nanotubes according to any one of claims 1 to 8, wherein the carbon nanotubes contain single-walled and / or 2-5-walled carbon nanotubes. 2. A carbon nanotube composition, wherein the liquid contains 0.01% by weight or more of carbon nanotubes, and the bulk density of the carbon nanotubes in the liquid is 50 g / liter or less, wherein the composition is according to claim 1. A carbon nanotube composition, which is obtained from a solution portion containing a large amount of carbon nanotubes recovered in the method for purifying a composition containing carbon nanotubes.