JP2004244309A - Method of manufacturing nanocarbon material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a nanocarbon material at a low cost, which is expected to be applied for a electrode material as an electric field electron emission source, an electrode material of a lithium secondary cell, a carbon material for supporting a catalyst for fuel cell and a hydrogen storage material of a hydrogen storage system. <P>SOLUTION: A raw material which is one or more kinds of compounds selected from a linear saturated hydrocarbon, a linear unsaturated hydrocarbon, a cyclic saturated hydrocarbon and alcohol in which the atomic ratio of contained carbon to contained oxygen is ≥2.0 is allowed to coexist with a super critical fluid or a subcritical fluid in the presence of one or more catalysts selected from transition metals, transition metal compounds, alumina, silica and silicon carbide. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a method for producing a nanocarbon material. More specifically, the present invention relates to a production method capable of mass-producing nanocarbon materials from inexpensive raw materials and a simple production apparatus.

  In 1985, fullerene, a soccer ball-like molecule consisting of 60 carbon atoms, was described by H.S. W. Kroto, R .; E. FIG. Smallly, R.A. F. Many application researches have been actively conducted since the discovery by Curl and the discovery of a carbon nanotube in the form of a tube formed by rolling a graphene sheet by Iijima in 1991.

  The carbon nanotube has excellent field emission performance, stores and releases lithium by an electrochemical reaction, has excellent field emission performance, and has a high specific surface area and good conductivity. Applications to electrode materials for display devices such as Emission Display, electrode materials for lithium secondary batteries, catalyst support layers for polymer solid electrolyte fuel cells, and the like have been studied.

  Conventionally, methods for producing carbon nanotubes include a method using an arc discharge in a gas atmosphere containing a carbon material such as hydrocarbons, a method using a laser evaporation method in which graphite is irradiated by irradiating a target with a laser, and a method using cobalt metal. Alternatively, a method is known in which a gas serving as a carbon material such as acetylene is thermally decomposed on a substrate provided with a nickel metal catalyst. Specifically, Patent Documents 1 and 2 disclose a manufacturing method using arc discharge, Patent Document 3 describes a manufacturing method using high-frequency plasma, Patent Document 4 describes a manufacturing method using a laser evaporation method, and Patent Document 5 describes a method using thermal decomposition. Manufacturing methods have been proposed respectively.

  On the other hand, Non-Patent Document 1 reports that filamentary carbon is produced by a hydrothermal synthesis reaction of 700 ° C., 100 MPa, and 150 hours using paraformaldehyde as a raw material. Non-Patent Document 2 reports that a multilayer carbon nanotube can be obtained from polyethylene as a raw material under hydrothermal reaction conditions of 700 to 800 ° C. and 100 MPa in the presence of Ni. Non-Patent Document 3 reports that multilayer carbon nanotubes can be obtained using amorphous carbon as a raw material under the conditions of a hydrothermal reaction of 800 ° C., 100 MPa, and 48 hours.

  Further, in Non-Patent Document 4, benzene as a raw material and a nickel-iron alloy as a catalyst are placed in an autoclave and reacted at a temperature of 480 ° C. and a pressure of 15 MPa to obtain a carbon nanotube having a multilayer structure.

JP-A-6-157016 JP-A-2000-95509 JP-A-9-188509 JP-A-10-273308 JP 2000-86217 A Carbon Vol. 36, no. 7-8, pp. 937-942, 1998 (Yury G. Gogotsi et al.) Journal of Materials Research Society, Vol. 15, No. 12, pp. 2591-2594, 2000 (Yury G. Gogotsi et al.) Journal of Amerian Chemical Society Vol. 123, No. 4, pp. 741-742, 2001 (Jose Maria Calderon et al.) Carbon Vol. 40, pp. 2961-2973, 2002

  However, in the conventional methods for producing a nanocarbon material represented by carbon nanotubes and carbon nanofibers described in Patent Documents 1 to 5, since the cost of raw materials and production equipment is high, the production cost of the nanocarbon material is low. It is expensive and difficult to synthesize in large quantities.

  In addition, the reports of Non-Patent Documents 1 to 3 all indicate that a reaction occurred in a gold capsule, and it was also reported that a nanocarbon material was generated under the conditions of 60 MPa or less. Not.

  Therefore, in order to produce a large amount of nanocarbon materials at a lower cost, a method that can be synthesized at lower temperature and lower pressure using lower-cost raw materials and equipment is desired.

Furthermore, in the method disclosed in Non-Patent Document 4, the ratio of the weight of the generated nanocarbon material to the weight of the catalyst in a 12-hour reaction is as small as 4.2, and a long time is required for the generation. Further, the results of Raman spectrum measurement of the obtained nano-carbon material, lattice defects of carbon near the peak and 1350 cm ^-1 called the G band near 1590 cm ^-1 due to lattice vibration within a six-membered ring network of carbon atoms The relative intensity of the peak called the D band due to the above is strong at around 1350 cm ^{-1 and} has many lattice defects. Therefore, a method for synthesizing a high-quality nanocarbon material having a short synthesis reaction time and few lattice defects is desired.

  As described above, nanocarbon materials are expected to be widely applied as electrode materials for secondary batteries, field electron emission sources for devices such as FEDs, carbon materials for supporting catalysts in fuel cells, and hydrogen storage materials for hydrogen storage systems. Therefore, there is great expectation for the development of a technology for producing this nanocarbon material at low cost.

  The present invention has been made in view of the above circumstances, and includes an electrode material as a field electron emission source of a device such as an FED, an electrode material of a lithium secondary battery, a carbon material for supporting a catalyst of a fuel cell, and a hydrogen storage system. It is an object of the present invention to be able to manufacture inexpensively a nanocarbon material expected to be applied as a hydrogen storage material or the like.

That is, the first present invention provides at least one kind selected from the group consisting of chain saturated hydrocarbons, chain unsaturated hydrocarbons, cyclic saturated hydrocarbons, and alcohols having an atomic ratio of carbon to oxygen of 2.0 or more. The raw material which is a compound of
In the presence of a catalyst comprising one or more substances selected from transition metal element-containing substances, alumina, silica and silicon carbide,
A method for producing a nanocarbon material, comprising a step of converting the raw material into a supercritical fluid or a subcritical fluid in a temperature range of 100 to 800 ° C. and a pressure of 0.2 MPa to 60 MPa. .

  In the present invention, in addition to the raw material and the catalyst as a supercritical fluid or subcritical fluid, a solvent for dissolving the raw material, a solvent for dissolving the catalyst, water, helium, argon, nitrogen, hydrogen, carbon monoxide, It is also preferable to add at least one selected from nitrous oxide and ammonia to contact the raw material.

  The second present invention provides at least one kind of raw material selected from chain saturated hydrocarbons, chain unsaturated hydrocarbons, cyclic saturated hydrocarbons, and alcohols having an atomic ratio of carbon to oxygen of 2.0 or more. And an auxiliary agent (reaction accelerating medium) for accelerating the nanocarbon formation reaction is added to a catalyst comprising one or more substances selected from a transition metal element-containing substance, alumina, silica, and silicon carbide. A temperature range of 0.2 MPa to 60 MPa and a pressure of 0.2 MPa to 60 MPa, the method comprising the steps of: contacting the reaction promoting medium with a supercritical fluid or a subcritical fluid to provide a method for producing a nanocarbon material. .

  The reaction accelerating medium may be at least one selected from a solvent dissolving the raw material, a solvent dissolving the catalyst, water, helium, argon, nitrogen, hydrogen, carbon monoxide, nitrous oxide, and ammonia. preferable.

  The solvent of the raw material is preferably at least one selected from carbon dioxide, aromatic hydrocarbons and ethers.

  The step of making the raw material a supercritical fluid or a subcritical fluid, or the step of bringing the reaction accelerating medium into contact with the raw material as a supercritical fluid or a subcritical fluid, in addition to the presence of a catalyst, in the presence of a surfactant Is also preferred.

  The raw material is preferably a liquid or a gas at normal temperature and normal pressure. The pressure is preferably in a range of 2 MPa to 40 MPa.

    The temperature is preferably in the range of 200 to 650 ° C.

  It is also preferable that the relative permittivity of the raw material at 25 ° C. is in the range of 1.5 to 25.0.

  Preferably, the transition metal element-containing substance is at least one selected from transition metals and transition metal compounds.

  The transition metal compound is preferably at least one compound selected from transition metal sulfides, transition metal carbides, organic transition metal compounds, transition metal nitrides, transition metal salts, and transition metal oxides.

  The transition metal element of the transition metal or transition metal compound is preferably at least one element selected from nickel, cobalt, iron, copper, silver, chromium, tungsten, molybdenum, titanium, ruthenium, rhodium and palladium. .

  Further, in the method for producing nanocarbon of the present invention, it is also preferable to further bake the obtained reaction product (nanocarbon) at a temperature of 400 to 2800 ° C. as a purification step for increasing the purity. This makes it possible to remove the remaining impurities and enhance the crystallinity of the nanocarbon.

  When it is not preferable to graphitize by heat treatment, it is more preferable to perform the calcination at a temperature of 600 to 2200 ° C.

  It is more preferable to perform the firing by firing at a temperature of 400 to 900 ° C. and then firing at a temperature of 900 to 2800 ° C. Firing at a temperature of 400 to 900 ° C. is effective for removing amorphous nanocarbon.

  The firing at a high temperature is preferably performed in an atmosphere of at least one gas selected from an argon gas, a helium gas, and a nitrogen gas.

  When the residual catalyst is a magnetic material, the residual catalyst or nanocarbon containing the residual catalyst can be separated and purified using a magnet.

  The nanocarbon material obtained by the production method of the present invention is an assembly of units having a shape selected from a filament (worm) and a tube. The diameter of the unit of the nanocarbon material having the above shape is in a range of 4 nm to 400 nm.

  The unit length of the obtained nanocarbon material is in the range of 100 nm to 100 μm.

  The nanocarbon material obtained by the production method of the present invention has a transition metal element in the unit or at the tip before the purification treatment.

  The transition metal element exists as a transition metal, transition metal oxide, transition metal carbide, or transition metal sulfide.

  Further, the nanocarbon material obtained by the present invention includes (a) a graphene sheet formed in a cup shape or a megaphone shape, and a large number of the cups or megaphones stacked and developed into a filament shape; A tube formed by being rolled up in a single layer or multiple layers parallel or inclined to the direction, (c) a platelet type in which graphene sheets are stacked perpendicularly to the fiber axis or to a fiber axis It has a microstructure selected from herring-bone type graphite nanofibers that are stacked at an angle, and (d) those that have developed into a spherical or disk-like shape.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method which can manufacture the nanocarbon material which has a possibility for various uses from an inexpensive raw material, and can also easily scale up large-scale synthesis can be provided.

  The present invention relates to a raw material that is at least one compound selected from the group consisting of chain saturated hydrocarbons, chain unsaturated hydrocarbons, cyclic saturated hydrocarbons, and alcohols having an atomic ratio of carbon to oxygen of 2.0 or more. In the presence of one or more catalysts selected from transition metal element containing materials, alumina, silica and silicon carbide, in a temperature range of 100 to 800 ° C. and a pressure of 0.2 MPa to 60 MPa, a supercritical fluid or a subcritical fluid. This is a method for producing a nanocarbon material characterized by including a step of forming a critical fluid or a step of coexisting with a supercritical fluid or a subcritical fluid.

  In the present invention, preferred specific chain saturated hydrocarbons used as a raw material include methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, It is preferably one or a mixture of two or more selected from hexadecane, heptadecane, octadecane, nonadecane, eicosane, isobutane, isopentane, dimethylbutane, trimethylpentane, methyloctane, methylheptane and methylpentane. Among them, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane are liquid or solid, and are more preferable in that they are easy to handle. Raw material. In terms of cost, n-hexane and methane are preferred raw materials.

  Preferred specific chain unsaturated hydrocarbons used for the raw material include ethylene, propene, butene, pentene, hexene, heptene, octene, nonene, decene, methylpropene, cyclohexene, cyclopentene, butadiene, propadiene, acetylene, and propyne. No.

  Preferable specific unsaturated chain hydrocarbons used as the raw material include propylene, ethylene, and butadiene because they are inexpensive and have a high conversion rate to a nanocarbon material.

  Preferred specific cyclic saturated hydrocarbons used for the raw material include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, methylcyclohexane, methylcyclopentane, dimethylcyclopentane, decalin. .

  Preferred alcohols having an atomic ratio of contained carbon to contained oxygen of 2.0 or more used as the raw material include ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, Examples include tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, isobutyl alcohol, propanol, t-butanol, methylbutanol, pentanol, cyclohexanol, and allyl alcohol. Examples of more preferable alcohols include propanol and butanol because they are inexpensive and have a high conversion rate to a nanocarbon material.

  Liquefied natural gas containing methane as the main component and containing ethane, propane, butane, nitrogen, carbon dioxide and sulfur compounds, or liquefied petroleum gas as a mixture of propane, propylene, normal butane, isobutane, butylene, isobutylene, etc. (Liquefied petroleum gas) is also a preferable material as a raw material of the nanocarbon material because it is inexpensive.

  Among the above-mentioned raw materials, unsaturated hydrocarbons are most preferable because the conversion ratio of the raw material to the nanocarbon material is high. It is presumed that the unsaturated hydrocarbon originally easily undergoes a polymerization reaction and easily forms a carbon bond of nanocarbon. The raw material is more preferably a liquid or a gas at normal temperature and normal pressure from the viewpoint that the product and the unreacted raw material are easily separated. Among them, liquid is more preferable from the viewpoint of easy handling, and gas is more preferable from the viewpoint of separation from the product. In order to facilitate the charging operation and to facilitate separation from the product after the completion of the reaction, it is also preferable to charge in a state of being liquefied or solidified by cooling a gaseous substance at normal temperature.

  The chain saturated hydrocarbon, the chain unsaturated hydrocarbon, the cyclic saturated hydrocarbon, and the predetermined alcohol used as the raw material can be used alone or in combination of two or more. Further, an aromatic compound can be used in combination with one or a mixture of two or more of them.

  The raw material is preferably a supercritical fluid or a subcritical fluid in a temperature range of 100 to 800 ° C. and a pressure of 0.2 MPa to 60 Pa higher than the atmospheric pressure. The critical temperature and critical pressure at which hexane, which is one of the above saturated hydrocarbons, becomes a supercritical fluid is 234.4 ° C. and 2.97 MPa. The critical temperature and critical pressure at which methane, which is one of the saturated hydrocarbons, becomes a supercritical fluid is −82.45 ° C. and 4.95 MPa. One of the unsaturated hydrocarbons, ethylene, has a critical temperature and critical pressure of 9.65 ° C. and 5.076 MPa, propylene has a critical temperature and critical pressure of 92 ° C. and 4.62 MPa, and has a critical temperature and critical pressure of acetylene. The pressure is 35.33 ° C. and 6.139 MPa. The critical temperature and critical pressure of 1-butanol which is one of the predetermined alcohols is 289.93 ° C. and 4.413 MPa.

  It is advantageous in terms of handling that the raw material has a boiling point of 30 ° C. or higher and is liquid or solid at room temperature, and is preferably gas or liquid at room temperature from the viewpoint of separability from the product. The raw materials can be used alone or in combination with other substances. This other substance is in contact with a raw material that has become supercritical or subcritical in a normal state (a state in which it has not reached supercritical or subcritical), that it comes into contact with a raw material that is in a supercritical or subcritical state, Alternatively, a substance (reaction promoting medium) serving as a medium for promoting the synthesis of a nanocarbon material from a raw material in a state where the raw materials are both supercritical or subcritical and come into contact with each other is preferable. More preferably, it is. In the case of using a raw material solvent in addition to the raw material in the synthesis reaction of the nanocarbon material, the relative dielectric constant of the raw material at 25 ° C. is 1.5 to 1.5 so that the raw material and the raw material solvent are uniformly mixed. It is preferably in the range of 25.0.

In the present invention, the supercritical fluid refers to a fluid having both liquid and gas properties in a temperature and pressure state exceeding a limit temperature and pressure (critical point) where gas and liquid can coexist, A subcritical fluid is a fluid equivalent to a supercritical fluid. Specifically, when the temperature (critical temperature) and pressure (critical pressure) at the critical point are T ₀ (absolute temperature) and P ₀ (MPa), A fluid that does not exceed a critical point at a temperature T (absolute temperature) and a pressure P (MPa) satisfying the following equation.

T ≧ 0.8T ₀
P ≧ 0.8P ₀

  In the reaction according to the present invention, the raw material, the catalyst and, if necessary, the reaction accelerating medium are placed in a pressure-resistant closed vessel, and the raw material is heated and pressurized to a temperature and pressure at which the raw material becomes a supercritical fluid or a subcritical fluid. Alternatively, the reaction can be performed by making the raw material that has become a subcritical fluid and the catalyst (and the reaction promoting medium) coexist. Also, the raw material, the catalyst, and the reaction promoting medium that forms a supercritical or subcritical fluid are placed in a pressure-resistant closed vessel, and the reaction promoting medium is heated and pressurized to a temperature and pressure at which the reaction promoting medium becomes a supercritical fluid or a subcritical fluid. The supercritical fluid or the subcritical fluid, the raw material, and the catalyst can coexist. In the latter, the raw material itself may also form a supercritical fluid or a subcritical fluid.

  The heating temperature and the pressurizing pressure are different depending on the substance forming the supercritical fluid or the subcritical fluid.However, from the viewpoint of easiness of reaction, cost reduction of used equipment, and reduction of operating energy, the temperature is 100 ° C. It is preferable to carry out at a temperature of 800 ° C. and a pressure in the range of 0.2 MPa to 60 MPa. From the viewpoint of the yield of the nanocarbon material, the equipment cost, and the equipment operation cost, from the viewpoint of the temperature of 300 ° C. to 800 ° C., more preferably the temperature of 300 ° C. to 650 ° C. and the pressure range of 2 MPa to 30 MPa, It is more preferable from the viewpoint of the yield of the carbon material, the device cost, and the device operation cost. It is preferable that the raw material of the nanocarbon material be in a supercritical fluid state under the reaction conditions in terms of increasing the reaction rate of the synthesis reaction. The raw material of the present invention has a critical pressure of 1.11 MPa or more.

  In addition, when a transition metal element-containing substance is used as a catalyst, the transition metal surface is generated during the reaction because the transition metal oxide is easily formed on the surface by the oxygen contained in the reaction vessel when the transition metal surface is handled in the air. It is necessary to expose a fresh transition metal surface by being reduced with hydrogen or carbon monoxide, and the reduction starting temperature of nickel oxide, cobalt oxide and iron oxide is around 200 ° C. It is preferable to carry out the reaction of nanocarbon synthesis at

  A substance that forms a supercritical fluid or a subcritical fluid other than the raw materials is a solvent for dissolving the raw materials, a solvent for dissolving the catalyst, water, helium, argon, nitrogen, hydrogen, carbon monoxide, nitrous oxide and ammonia. It is preferable that at least one or more selected from the above. The solvent for dissolving the raw material, the solvent for dissolving the catalyst, water, helium, argon, nitrogen, hydrogen, carbon monoxide, nitrous oxide, and ammonia function as a medium for promoting the synthesis of nanocarbon material from the raw material. It is supposed to be. Further, since the supercritical or subcritical fluid has a low relative dielectric constant and the relative permittivity of the raw material is low, the supercritical or subcritical fluid is considered to be a good solvent for the raw material. Therefore, it is preferable that the heating and pressurization exceed the critical temperature and the critical pressure. Further, when the raw material itself is in a supercritical fluid or a subcritical fluid, it is in a very active state and in a state in which a reaction easily occurs. In the synthesis of the nanocarbon material according to the present invention, it is most preferable that both the raw material and the fluid other than the raw material used in the synthesis are in a supercritical state.

  In the present invention, the raw material and the reaction promoting medium are preferably substances that become a supercritical fluid in a temperature range of 100 to 800 ° C. and a pressure of 0.2 MPa to 60 MPa.

  The size of the synthesized nanocarbon material greatly depends on the size of the catalyst particles. In order to obtain a uniform nanocarbon material, it is necessary to make the catalyst particles finer and to uniformly contact the raw material. For this reason, it is more preferable to mix the raw material and the solvent of the catalyst with the raw material and the catalyst. Specific examples of the solvent in which the raw material or the catalyst is dispersed or dissolved include carbon dioxide, water, hydrocarbons, alcohols, ethers, aromatic compounds such as toluene and benzene, and one kind or a mixture of two or more kinds may be used. Can be. In addition, carbon dioxide, in addition to functioning as a solvent, since the carbon dioxide itself has poor reactivity, it is estimated that the occurrence of side reactions is suppressed by reducing the probability of collision between molecules of the raw material, Most preferred among solvents. Incidentally, the critical temperature and critical pressure at which carbon dioxide becomes a supercritical fluid are 31 ° C. and 7.4 MPa. The critical temperature and critical pressure at which water becomes a supercritical fluid are 374 ° C. and 22.0 MPa. The critical temperature and critical pressure at which toluene, which is one of aromatic compounds, becomes a supercritical fluid is 319 ° C. and 4.11 MPa.

  Inert gases, such as argon gas, helium gas, and nitrogen gas, also have the effect of reducing the probability of collision between the raw material molecules and suppressing the occurrence of side reactions, thereby synthesizing a desired nanocarbon material with high purity. It is inferred. In addition, hydrogen gas keeps the catalyst surface active due to its reducing and etching effects, suppresses side reactions such as the formation of structurally unstable amorphous carbon, and provides strong stability of nanocarbon. It is presumed that it has the effect of promoting the growth of only the union. Hydrogen gas is also generated from the decomposition reaction of the raw material.

  The raw material is itself a supercritical fluid or a subcritical fluid, or in the presence of a supercritical fluid or a subcritical fluid by a reaction promoting medium, a material selected from transition metal element-containing substances, silica, silicon carbide, and alumina. Alternatively, when the catalyst is brought into contact with two or more kinds of catalysts, a nanocarbon material is formed from a raw material based on a transition metal or a transition metal compound, and grows. This is presumably because the transition metal element-containing material, alumina, silica, and silicon carbide have a catalytic action. A catalyst in which a transition metal element is supported on silica, zeolite or alumina may be used as the catalyst. Among the above catalysts, the one that produces the most filamentous nanocarbon material is the one in which the transition metal element is in a metal state having a valence of zero during the reaction. Specific examples of the catalyst are more preferably transition metal fine powder, those in which a transition metal is supported on a carrier having a high specific surface area, and organometallic compounds which become transition metal fine powder by thermal decomposition.

  A transition metal element-containing substance, a catalyst selected from alumina, silica, and silicon carbide are placed in a pressure-tight container together with the raw material and the reaction promoting medium, and the raw material and the reaction promoting medium become a supercritical fluid or a subcritical fluid. Sometimes, the catalyst is brought into contact with them, but this catalyst is not only an externally added one, but also a catalyst that has coexisted with the raw material or the reaction promoting medium from the beginning, or a supercritical fluid or a subcritical fluid of the raw material and the reaction promoting medium. It may be generated by contact with a critical fluid. Further, the material constituting the reaction vessel may serve as a catalyst. A plurality of types of catalysts may be used as the catalyst. Examples of the transition metal element-containing substance include transition metals, transition metal compounds, and substances in which a transition metal element is supported on an oxide having a large specific surface area, such as silica or zeolite. The carrier for supporting the catalyst is not limited to oxides, but may be a carbon material such as activated carbon having a large specific surface area. Two or more transition metal elements may be supported.

  Examples of the transition metal elements constituting the transition metal and the transition metal compound include Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Ta, W, Pt, and Au. Among them, Ni, Co, Fe, Cu, Cr, W, Mo, Ti, V, Mn, Ru, Rh, Pd, and Ag are more preferable elements, and Ni, Co, Fe, Cr, W, Mo, and Ti are the most preferable elements. It is a preferred element.

  The transition metal compound is preferably a transition metal oxide, a transition metal hydroxide, an organic transition metal compound, a transition metal sulfide, a transition metal carbide, a transition metal nitride, or a salt of a transition metal. Among them, an organic transition metal compound is preferable as a catalyst except that it is easily decomposed to form a fine transition metal powder having a large specific surface area and is not inexpensive. The transition metal oxide, transition metal hydroxide, or transition metal salt functions as a catalyst by being reduced by hydrogen generated by a decomposition reaction of the raw material under a high temperature and a high pressure and converted into a fine transition metal powder. Since the transition metal salt is reduced or oxidized into a transition metal or a transition metal oxide in the reaction of the production method of the present invention, the transition metal salt can be dissolved in an acid and recovered as a transition metal salt. It is preferable because it can be used. However, nitrates and sulfates as the above-mentioned transition metal salts easily generate oxygen, and thus it is not preferable to use them alone.

  Preferred examples of the organic transition metal compound include ferrocene, nickelocene, nickel formate, nickel oxalate, nickel naphthenate, nickel phthalocyanine, cobalt phthalocyanine, copper phthalocyanine, nickel acetylacetonate, cobalt acetylacetonate, iron acetylacetonate, Copper acetylacetonate, nickel carbonyl, cobalt carbonyl, iron carbonyl, bis (triphenylphosphine) dicarbonylnickel, dibromobis (triphenylphosphine) nickel and chlorotris (triphenylphosphine) rhodium. The carbon element contained in the organic transition metal compound may be converted into a part of the nanocarbon material used and generated during the synthesis reaction. The catalyst in the present invention refers to a catalyst in a broad sense including one in which a decomposition product has a catalytic action.

  When the diameter of the unit constituting the nanocarbon material obtained by the method of the present invention depends on the particle size of the catalyst, it is important to control the catalyst particle size. In order to obtain a nanocarbon material having a small diameter and uniform size, (i) a catalyst is dispersed and supported on a carrier having a large specific surface area, or (ii) a solvent dissolving the catalyst in addition to the catalyst is used. It is preferable to further introduce a surfactant in order to prevent introduction or aggregation of the catalyst.

  In the present invention, at the time of synthesizing a nanocarbon material from a raw material, in order to further promote the synthesis of the nanocarbon material, one or more selected from sulfur and a sulfur compound are added to the transition metal or the transition metal compound. May be. These may be effective in controlling the growth direction of the nanocarbon material. As the sulfur compound, thiol, thioacetamide, thionaphthene, thiosemicarbazide, thiourea, and thiophene are preferable, and thiol is particularly preferable. These sulfur and sulfur compounds are not limited to those externally added, and may be those that coexist with the above-mentioned raw materials from the beginning. In particular, the raw materials often contain sulfur and / or a sulfur compound, and the sulfur and / or the sulfur compound present in the raw material can be replaced with these external additives. Examples of the thiol include 1-octanethiol (n-octylmercaptan), 1-decanethiol (n-decylmercaptan), 1-dodecanethiol (n-dodecylmercaptan), n-butylmercaptan, propylmercaptan, and ethylmercaptan. , Methyl mercaptan, benzyl mercaptan, and thiophenol.

  The present invention preferably has a firing step. That is, it is preferable that after the nanocarbon material is generated from the raw material, the generated nanocarbon material is fired. By firing, the remaining impurities can be removed. Further, by performing this firing, the purity of the nanocarbon material can be increased, and the development of the graphene structure can be improved. It is also preferable to remove the catalyst by washing with an acid or the like before or after the calcination. Further, by setting the firing temperature to 1500 ° C. or higher, it is possible to remove the catalyst remaining on the generated nanocarbon material by sublimation.

  The calcination is preferably performed at a temperature of 400 to 2800 ° C. from the viewpoint of removing the impurities and improving the yield. In addition, from the same viewpoint, it is preferable to perform the reaction under an inert gas atmosphere. As the inert gas, one or a mixture of two or more gases selected from argon gas, helium gas and nitrogen gas is preferable.

  The baking is preferably performed a plurality of times at different temperatures in order to more reliably remove impurities and improve the yield. For example, it is preferable that after baking on the low temperature side of the above temperature range, baking is performed on the middle to high temperature side of the above temperature range. Specifically, after baking at 400 to 800 ° C., it is preferable to bake at 900 to 2800 ° C., more preferably at a temperature of 600 to 2200 ° C. In addition, it is more preferable that the firing be performed at a low temperature of 400 to 800 ° C. and then at 1000 to 2200 ° C. in order to develop the graphene structure of the nanocarbon material. Further, in the case of performing baking a plurality of times, it is preferable to perform crushing with a mill or the like between the baking, because baking can be performed more uniformly. Firing at 2200 to 2800 ° C. tends to develop a graphite structure.

  The nanocarbon material obtained by the synthesis method of the present invention varies depending on the raw material and catalyst, the substance of the supercritical fluid or subcritical fluid, and the temperature and pressure conditions of the synthesis. The shape observed from the microscope is a shape selected from a filament shape (worm shape) and a tube shape. An assembly of these units is obtained by the production method of the present invention. The diameter of the unit of the nanocarbon material having the above shape is in a range of 4 nm to 400 nm, and its length is in a range of 100 nm to 100 μm. Further, in the production method of the present invention, a filament (worm-like) or tube-like nanocarbon material is easily obtained with higher purity. Further, the diameter of the nanocarbon easily depends on the particle diameter of the catalyst particles, and the diameter of the nanocarbon can be controlled by controlling the particle diameter of the catalyst particles.

  Further, from a transmission microscope observation of the above unit, the nanocarbon material obtained by the present invention is (a) a graphene sheet formed in a cup shape or a megaphone shape, and a large number of the cups or megaphones are stacked to develop into a filament shape; (B) a graphene sheet which is rolled in a single layer or a multilayer in a direction parallel or inclined to the fiber axis direction to form a tube; and (c) a platelet in which the graphene sheet is laminated perpendicular to the fiber axis. ) Has a microstructure selected from a herring-bone type graphite nanofiber stacked obliquely with respect to the fiber axis or the fiber axis, and (d) those developed into a spherical or disk-like shape. . The diameters of the above structures (a), (b), and (c) are in the range of 4 nm to 400 nm, and often in the range of 20 nm to 400 nm. The filamentary (worm-like) or tubular nanocarbon produced by the method of the present invention can easily obtain the fine structure of the above-mentioned shape (a) or (b) with high purity and high yield. According to the method of the present invention, the nanocarbon having the shape (a) is easily obtained.

  In addition, when a transition metal element-containing substance is used as a catalyst, the nanocarbon material is considered to develop in many cases based on the transition metal element used, and most of the synthesized nanocarbon material is at the tip or inside. The transition metal or the transition metal compound derived from the catalyst remains. The residual transition metal element can be removed by dissolving with an acid or alkali. Further, by performing a heat treatment at 1500 ° C. or higher, residual transition metal elements can be removed.

  In the present invention, it is preferable to have a purification step after the above-mentioned firing step.

  In the present invention, when a transition metal or a transition metal compound that is a magnetic substance is used as the transition metal or the transition metal compound, for example, iron, nickel, cobalt or a compound thereof, the obtained nanocarbon material is Is contained. Therefore, it is possible to use a magnet (electromagnet, permanent magnet) to collect the nanocarbon material containing the magnetic material, and to increase the purity. Specifically, the purity of the nanocarbon material can be increased by dispersing the nanocarbon particles in a liquid such as alcohol or water by ultrasonic irradiation or the like, and then collecting the particles using a magnet.

  In the purification step of the present invention, in addition to the purification using the magnet, the residue remaining in the transition metal or the transition metal compound-derived nanocarbon material is converted into an acid (eg, nitric acid, hydrochloric acid, sulfuric acid, hydrofluoric acid, etc.) or A step of dissolving and removing with an alkali (for example, sodium hydroxide, potassium hydroxide, or the like), followed by washing and drying can also be used.

  Depending on its use, the nanocarbon material may preferably have a residue derived from the catalyst inside or at the tip of the unit constituting the nanocarbon material. In such a case, the acid or alkali purification need not be performed. However, when the catalyst is used for an application in which the residual transition metal or transition metal compound derived from the catalyst may have an adverse effect, it is preferable to perform the above purification step.

  Further, the refining step in the present invention may be a step in which after the refining with the magnet, the dissolution and removal with the acid or alkali, and the washing and drying are performed.

  In addition, even in the case of the above-described purification using a magnet, in the case of purification using an acid or an alkali, the entangled nanocarbon aggregates can be loosened by performing crushing with a mill or the like prior to the purification treatment, thereby improving the purification efficiency. It is preferable because it can be performed.

  FIG. 1 shows a flowchart of the manufacturing method according to an example of the present invention described above. Step 1 in FIG. 1 includes deoxidizing a raw material, a catalyst, a reaction accelerating medium (a solvent for dissolving the raw material, a solvent for dissolving the catalyst, and a medium for promoting the reaction of the raw material) and an inert gas as necessary. This is a preparation step of putting the mixture into the pressure-resistant reaction vessel that has been subjected to the above. Step 2 is a step of heating and pressurizing them in a pressure-resistant reaction vessel to make the raw material and / or the reaction promoting medium a supercritical fluid or a subcritical fluid, and reacting the raw materials for a predetermined time. And a step of separating the unreacted raw materials to obtain a nanocarbon material. Thereafter, if necessary, the nanocarbon material obtained in step 3 is heated in step 4 to 400 to 2800 ° C., preferably in an inert gas atmosphere, or the remaining catalyst is removed. Purify. However, depending on the use of the obtained nanocarbon material, it is not necessary to carry out the steps 3 and 4.

  As an example of a reactor for preparing a nanocarbon material by the above-described manufacturing method, as shown in FIG. 2, a high-temperature and high-pressure reactor 200 equipped with a pressure gauge 206, a heating device 203, and a safety valve 207 is used. In FIG. 2, 201 is a raw material or a raw material and a reaction promoting medium such as carbon dioxide, 202 is a catalyst, 204 is a raw material storage container, 205 is a storage container for a reaction promoting medium such as carbon dioxide, 206 is 207, 208 is an exhaust device. , 209 are supply pipes of the raw material or the reaction promoting medium, 210 is an exhaust pipe, and 211 is a stirring mechanism. The material of at least 200 inner walls of the reaction vessel is preferably made of stainless steel, and more preferably made of a Ni-Mo alloy in terms of corrosion resistance. Further, in order to increase the yield from the raw material, a desired reaction product (nanocarbon material) is separated from the reaction product containing the unreacted raw material, and the raw material is returned to the reaction vessel again. (Shown) is more preferable.

  In the present invention, the inside of the high-temperature and high-pressure reactor 200 containing the catalyst 202 is exhausted by the exhaust device 208 to perform deoxygenation, and a predetermined amount of the raw material 201 is supplied from the raw material storage container 204 to the high-temperature and high-pressure reactor. A predetermined amount of a reaction promoting medium such as carbon dioxide is supplied from the reaction promoting medium storage container 205 in accordance with the condition. Thereafter, the raw material or the reaction promoting medium is heated by a heating device 203 to a predetermined temperature and a predetermined pressure exceeding a critical point at which the raw material or the reaction promoting medium becomes a supercritical fluid. To synthesize a nanocarbon material from the raw material.

  FIG. 3 is an example showing an outline of a manufacturing apparatus for continuously manufacturing a nanocarbon material by the method of the present invention. In FIG. 3, reference numeral 300 denotes a high-temperature and high-pressure reactor, 301 denotes a product (produced nanocarbon material) separator, 302 denotes a raw material recovery and purification tower, 303 denotes a compressor, 304 denotes a feed material, 305 denotes a feed catalyst, and 306 denotes a necessary catalyst. The reaction-promoting medium 307 supplied accordingly is the product nanocarbon material. In the present invention, first, a raw material 304, a catalyst 305, and a reaction promoting medium 306 such as carbon dioxide are supplied to a sufficiently deoxygenated high-temperature and high-pressure reactor 300 so that the raw material or the reaction promoting medium is a supercritical fluid. After reacting for a predetermined time under the temperature and pressure to form a mixture, the mixture of the product and the unreacted raw material is sent to the product separator, and the nanocarbon material 307 of the product and the unreacted raw material 304 are separated, The unreacted raw material is sent to a raw material recovery / purification tower 302, and the recovered unreacted raw material 304 is sent to a high-temperature high-pressure reactor 300 through a compressor 303. Subsequently, a raw material 304, a catalyst 305, and a reaction promoting medium 306 such as carbon dioxide are supplied as needed, and reacted under predetermined conditions to produce a nanocarbon material.

  The shape of the nanocarbon material can be confirmed with a scanning electron microscope (SEM), and the fine structure can be confirmed with a transmission electron microscope (TEM).

The ratio of the amorphous component contained in the nanocarbon material can be analyzed by X-ray diffraction and laser Raman analysis. The Raman scattering spectrum of the carbon nanotube, a peak due to lattice vibration within a six-membered ring network of carbon atoms, called G band around 1528～1606Cm ^-1 further due to lattice defects of carbon in the vicinity of 1353cm ^-1 A peak Raman line called D band is observed. The X-ray diffraction peak is sharp if the purity is high, and broad if the amorphous content is high. When a large amount of amorphous carbon is contained, a large peak near 1353 cm ^{-1 in} the Raman spectrum is observed. Thus, the purity of the nanocarbon material is evaluated by the shape check by the main scanning microscope, the other, TEM observation, the half width of the X-ray diffraction peaks, 1353Cm to the peak intensity at around 1528～1606Cm ^-1 of Raman spectrum ^- It can be evaluated based on a peak intensity ratio near ¹ .

  In addition, the performance evaluation of a negative electrode material of a lithium secondary battery was performed by constructing a cell using an electrode made of a nanocarbon material as a working electrode, a lithium metal as a counter electrode, and a solution in which a lithium salt was dissolved in a non-aqueous solvent as an electrolyte. It can be performed by chemically inserting and removing lithium from an electrode made of a nanocarbon material, and comparing the amount of electricity with the amount of insertion and the amount of desorption.

  The performance evaluation of the FED as a cathode can be performed by measuring the current value per unit area when an electric field is applied between the electrode made of a nanocarbon material as a cathode and an opposing anode under reduced pressure. it can.

  The performance evaluation of hydrogen storage can be performed by storing hydrogen gas at a low temperature, measuring the amount of hydrogen desorbed by increasing the temperature, and calculating the hydrogen storage amount per unit weight.

  When the obtained nanocarbon material is used for a catalyst-supporting layer such as platinum of a fuel cell, the performance evaluation is performed by measuring the specific surface area, the specific resistance measurement, the nanocarbon And the output characteristics of a fuel cell using a carbon layer carrying a catalyst such as platinum. The specific surface area is preferably high, the specific resistance value is preferably low, and the supported catalyst particles such as platinum are preferably small.

  The nanocarbon material produced according to the present invention can be used as an electrode material of a lithium secondary battery, a cathode material of an FED, and a catalyst supporting layer of a fuel cell. Hereinafter, the case where it is used for these uses will be described.

[Lithium secondary battery]
When a nanocarbon material is applied to a lithium secondary battery (herein, a lithium secondary battery including a so-called lithium ion secondary battery) is used as a negative electrode material that stores and releases lithium ions, It is preferably used as a conductive auxiliary material of a negative electrode material and a conductive auxiliary material of a positive electrode material that stores and releases lithium ions. FIG. 4 is a conceptual diagram of the configuration of a lithium secondary battery. 4, reference numeral 401 denotes a negative electrode, 402 denotes an ion conductor, 403 denotes a positive electrode, 404 denotes a negative electrode terminal, 405 denotes a positive electrode terminal, and 406 denotes a battery housing (container). The negative electrode 401 in FIG. 4 includes the electrode structure 505 in FIG.

  The electrode structure shown in FIG. 5 is a case where a nanocarbon material is used as a negative electrode material that stores lithium ions by charging and discharges them by discharging. In FIG. 5, 500 is a current collector, 501 is a nanocarbon material powder, 502 is a binder, 503 is a conductive auxiliary material, and 504 is an active material layer. On the other hand, in the other electrode structure (negative electrode) 505, when silicon, tin, or an alloy thereof that stores lithium ions by charging and discharges them by discharging is used instead of the nanocarbon material in 501, the method of the present invention is used. Since the nanocarbon material manufactured by the method is minute and has high conductivity, the nanocarbon material manufactured by the present invention can be used as the conductive auxiliary material 503.

  The electrode structure 505 made of the nanocarbon material in FIG. 5 can be formed as follows.

  That is, a binder 502 composed of an organic polymer is mixed with the nanocarbon material powder 501, and a conductive auxiliary 503 and a solvent are appropriately added and mixed as necessary, and the mixture is mixed with a current collector 500 such as a copper foil. The electrode structure 505 can be formed by stacking the negative electrode active material layer 504 over the electrode structure. This electrode structure 505 is used as the negative electrode 501 of the battery of FIG.

  The positive electrode 403 in FIG. 4 includes a lithium-transition metal oxide, a lithium-transition metal phosphate compound, or a lithium-transition metal sulfide powder, a conductive auxiliary material such as graphite powder, and a binder made of an organic polymer. A solvent in which a solvent is appropriately added and mixed, and this mixture is arranged on a current collector such as an aluminum foil to form a positive electrode active material layer can be used. As the transition metal element of the lithium-transition metal oxide, lithium-transition metal phosphate compound or lithium-transition metal sulfide of the positive electrode material, cobalt, nickel, manganese, iron and the like are preferably used.

  Since the nanocarbon material produced by the method of the present invention is minute and has high conductivity, the nanocarbon material produced by the present invention can be used as the conductive auxiliary material. In this case, the structure of the positive electrode is an electrode structure in which 501 in FIG. 5 is a positive electrode material such as a transition metal-lithium composite oxide, and a nanocarbon material can be used as the conductive auxiliary material 503.

  A microporous polyolefin-based film holding a lithium salt electrolyte is disposed as a separator between the negative electrode 401 and the positive electrode 403, and functions as an ion conductor 402, thereby forming a lithium secondary battery.

As the binder, a fluororesin such as polyvinylidene fluoride or a water-soluble polymer such as polyvinyl alcohol is used. Examples of the electrolyte include lithium ions (Li ⁺ ) and Lewis acid ions (BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , N (CF ₃ SO ₂ ) ₂ ⁻ , BPh _4. ^-: the lithium salt comprising (Ph phenyl group)), ethylene carbonate, propylene carbonate, dimethyl carbonate, or using an electrolytic solution dissolved in an organic solvent such as diethyl carbonate, or gelled by adding a polymer It may be something. As the microporous polyolefin-based film of the separator, a polyethylene film or a polypropylene film is used.

[FED]
FIG. 6 is a schematic sectional configuration diagram of the FED. In FIG. 6, 600 is an insulating substrate (glass substrate), 601 is a back electrode (cathode electrode), 602 is a nanocarbon layer (cathode) such as carbon nanotube, 603 is an insulating spacer (partition), 604 is a phosphor layer, 605, a transparent electrode (anode); 606, a surface mask; 607, a transparent surface material (glass plate).

  The FED in FIG. 6 is obtained by disposing a pattern of a metal electrode 601 on a glass substrate 600, mixing the binder with the nanocarbon material powder on the pattern of the metal electrode 601 and adding a solvent to form a paste. A transparent electrode 605 pattern is formed on a cathode 602 and a glass substrate 607 formed by applying, drying and firing by a method such as screen printing, and a phosphor layer 604 is formed on the transparent electrode pattern (anode) 605 by a screen printing method. Then, the anode 605 and the cathode 602 are opposed to each other, a spacer (partition wall) 603 is disposed between the anode 605 and the cathode 602, and the container can be hermetically sealed after being evacuated to a vacuum.

  The current-voltage characteristic of the field emission from the nanocarbon material is obtained by forming an element having a schematic sectional structure shown in FIG. 7, inserting the element into a vacuum chamber with a current introduction terminal, and connecting the anode 704 and the cathode 701 made of the nanocarbon material. Can be obtained by applying a voltage to and measuring the current.

  7, reference numeral 700 denotes an insulating substrate, 701 denotes a cathode, 702 denotes a cathode of a nanocarbon material, 703 denotes an insulating spacer, 704 denotes an anode, 705 denotes a cathode lead, and 706 denotes an anode lead.

The element for measuring current-voltage characteristics of the field emission shown in FIG. 7 is, for example, a glass substrate (for example, # 7059 glass manufactured by Corning Incorporated) 700 in which a cathode pattern provided with a lead portion of an electrode is brought into close contact with a mask or the like, which is removed by etching. After that, a chromium (50 nm) / aluminum (300 nm) / chromium (50 nm) film is deposited by a method such as electron beam evaporation to obtain a cathode pattern 701. Next, the crushed nanocarbon material is dispersed in isopropyl alcohol by ultrasonic irradiation, the cathode pattern is immersed, and a direct current electric field is applied between the cathode electrode and the counter electrode to deposit the nanocarbon on the cathode pattern 701 to form a cathode. A nanocarbon layer 702 is formed. Next, an insulating material such as mica having a thickness of about 20 to 200 μm is attached on the cathode as an insulating spacer 703, and an aluminum plate as an anode is attached thereon as an anode 704, and a chrome / aluminum / chromium extraction electrode is attached. It can be manufactured by connecting the cathode lead 705 and the anode lead 706 to the aluminum plate. The current-voltage characteristics of the field emission from the nanocarbon material were measured by storing the element in a vacuum chamber in which the degree of vacuum was maintained at 10 ⁻³ Pa or less, and applying a high voltage between the cathode lead 705 and the anode lead 706. By applying a voltage and measuring the current at that time, the field emission characteristics can be measured.

(Hydrogen storage material)
The hydrogen storage capacity of carbon nanotubes can be measured by the measuring device of FIG. 8 in which a nanocarbon material-filled container whose volume has been measured in advance and a hydrogen storage container whose volume has also been measured are connected via an open / close valve.

  8, 800 is a high-pressure hydrogen cylinder, 801 is a hydrogen storage container, 802 is a nanocarbon material filled container, 803 is a temperature controller, 804 is a vacuum pump, 805 is a pressure gauge, 805 is a vacuum gauge, 807 is a vacuum gauge, 807 is a pressure regulating valve, 808. , 809, 810, 811, 812, 813 are open / close valves.

  The nanocarbon material-filled container 802 is provided with a vacuum gauge 806 coupled via open / close valves 811, 812, 813 and a vacuum pump 804 coupled via open / close valves 811, 812. A hydrogen cylinder 800 is connected to the hydrogen storage container 801 via a switching valve 808 and a pressure regulating valve 807.

  The weight of the sufficiently dried nanocarbon material powder is measured, the nanocarbon material powder to be measured is inserted into the nanocarbon material powder filling container 802, and after being evacuated to a high vacuum region by the vacuum pump 804, a predetermined amount is measured. Open / close valves 810 and 811 are introduced from the hydrogen storage container 801 at a pressure of 2 to the nanocarbon material powder filling container 802 to introduce hydrogen, and after a predetermined time elapses, the hydrogen in the two containers (801 and 802) which are in conduction is introduced. The pressure is measured, and the hydrogen storage amount per unit weight of the nanocarbon material powder can be calculated from the hydrogen pressure of the first hydrogen storage container 801 and the volumes of the two containers. Actually, while changing the pressure of hydrogen introduced into the nanocarbon material powder filling container 802, the amount of occlusion / release at equilibrium pressure is measured, and the amount of occluded hydrogen per unit weight is calculated.

  Hereinafter, the present invention will be described in detail based on examples. Note that the present invention is not limited to these examples.

Example 1
After mixing 2.5 g of n-hexane (critical temperature: 234.4 ° C., critical pressure: 2.97 MPa) and 0.2 g of nickelocene in a pressure-resistant container made of Hastelloy (Ni-Mo alloy) having an internal volume of 95 ml. , 30 g of dry ice was added, and the mixture was sealed. A small amount of carbon dioxide vaporized at room temperature was discharged, the pressure was adjusted, and the mixture was reacted at a temperature of 650 ° C. and a pressure of 23 MPa for 2 hours. Then, the mixture was cooled to room temperature, the reaction vessel was opened, and the solid content was taken out and dried to obtain 0.54 g of a reaction product.

  The reaction product obtained by the above operation was observed with a scanning electron microscope and a transmission electron microscope, and X-ray diffraction analysis and Raman spectrum measurement were performed.

In the scanning electron microscope observation of the reaction product, an image in which countless counts of nanocarbons in a filament-like unit such as the worm of FIG. 9 were collected at almost 100% was observed. At the same time, from the measurement of X-ray microanalysis, nickel as a residual catalytic element was observed at the tip of the filament, and no other elements other than the carbon element were observed. Further, in the X-ray diffraction analysis, an analysis peak based on graphitic carbon and an analysis peak based on nickel metal were observed. From these facts, it is presumed that nickelocene used as a catalyst decomposed during the reaction to become nickel metal. From the Raman spectroscopy, peaks called peak and weak 1350 cm ^-1 vicinity of D band called G band near 1590 cm ^-1 were observed. That is, the relative intensities of the peaks in the vicinity of ^-1 peak near 1590 cm ^-1 of the obtained nano-carbon material and 1350cm, the peak intensity at around 1590 cm ^-1 was strong.

  A transmission electron microscope observation of the nanocarbon observed by the above scanning electron microscope was carried out and observed at a low magnification. In FIG. 10, it was found that the carbon nanotube was a kind of a so-called carbon nanotube having a hollow central portion. FIG. 11 is a transmission electron microscope image observed at a high magnification. 9 and 10, from the results of X-ray microanalysis and X-ray diffraction measurement, the nanocarbon material obtained by the above operation is a nanocarbon material having a hollow tube structure grown from the surface of nickel metal fine particles as shown in FIG. It turned out to be.

  FIG. 13 is a schematic view of a possible microstructure of filamentary nanocarbon. FIG. 13 (1) shows a graphene sheet developed in a megaphone shape in which a large number of graphene sheets are stacked and grown in a tube shape. , (2) is a graphene sheet developed in a cup shape and grown in a columnar shape, (3) is a graphene sheet stacked vertically to a fiber axis and grown in a columnar shape, (4). Is a graphene sheet grown concentrically parallel to the fiber axis and grown in a tube shape, and (5) is a graphene sheet in which several graphene sheets are overlapped and rolled while rotating in the fiber axis direction to grow in a tube shape. Showing things.

  From the image of FIG. 11, it can be seen that the microstructure of the filamentary nanocarbon material obtained by the above operation is the structure of (1) or (5) shown in FIG. Further, in a transmission electron microscope observation of other portions of the obtained nanocarbon material, a portion close to the structure of FIG. 13 (2) was observed, and a portion likely to be the structure of FIG. 13 (4) was partially observed. Was done.

Even after firing of the obtained nanocarbon at 1500 ° C. and 2800 ° C. in an argon gas atmosphere, the filamentary unit shape as shown in FIG. 9 was maintained. By the above calcination, the peak at 1350 cm ^{-1 in} the Raman spectrum almost disappears. The shape of the unit constituting the obtained nanocarbon material was hardly changed. The nanocarbon unit obtained from FIG. 9 had an average diameter of about 10 to 100 nm and a long length of about 4 μm or more. The inner diameter (diameter of the hollow part) of the nanocarbon having an outer diameter of about 87 nm was about 30 nm.

  Next, nickel remaining in the nanocarbon material after firing at 1500 ° C. obtained by the above operation is dissolved and removed with hydrochloric acid and nitric acid, washed with ion-exchanged water, heat-treated at 350 ° C. in air, and pulverized by a ball mill. A sample for measuring field emission characteristics was used. Next, the pulverized carbon nanotubes were dispersed by irradiating ultrasonic waves to isopropyl alcohol, a DC electric field was applied to form a nanocarbon material layer on a stainless steel substrate by electrophoresis, and the cathode shown in FIG. 7 was formed. Next, a field electron emission device having a device structure shown in FIG. 7 was assembled using an aluminum plate as the anode and a mica plate having a thickness of 150 μm as the spacer. An electric field was applied to the device manufactured by the above operation in a vacuum chamber, and current-voltage characteristics of field emission were measured. As a result, it was found that the threshold voltage was 5 V / μm or less, and an electron emission current value approximately 10 times superior to that of a commercially available multi-walled nanotube manufactured by Honjo Chemical Co., Ltd. was obtained.

An electrode is formed using the nanocarbon material obtained by the above-mentioned operation after firing at 1500 ° C. as the nanocarbon material for the electrode 501 in FIG. 5, and lithium metal is used as a counter electrode, and a microporous polypropylene film is used as a separator between the electrodes. Lithium fluoroborate (LiBF ₄ ) was electrochemically inserted and desorbed from lithium using an electrolyte prepared by dissolving 1 mol / l in a 3: 7 mixed solvent of ethylene carbonate and diethyl carbonate. It was found that 1.2 times as much lithium as natural graphite could be stored. This means that a battery having a higher capacity can be formed by manufacturing the secondary battery of FIG. 4 using the electrode manufactured as described above as a negative electrode than an electrode formed using natural graphite.

  In addition, in the measurement with the hydrogen storage capacity measuring device having the configuration shown in FIG. 8, the obtained nanocarbon with the nickel metal remaining before firing had the same hydrogen storage capacity as the multi-walled carbon nanotube manufactured by Honjo Chemical Co., Ltd. I understood.

Example 2
A nanocarbon material was prepared in the same manner as in Example 1 except that the temperature was 450 ° C., the pressure was 14 MPa, and the reaction time was changed to 6 hours. At this time, when the raw materials, the catalyst and the dry ice were charged into the reaction vessels, the amounts of oxygen and water in the two reaction vessels were not strictly controlled to be identical. The yields of the obtained nanocarbon were 0.40 and 0.82 g. This difference in yield is considered to be affected by the history of the reaction vessel, the amount of oxygen in the system, and the amount of water. It is considered that nickelocene is easily affected by oxygen or moisture because the valence of nickel changes depending on the storage state in the air.

  In the scanning electron microscope observation of the obtained nanocarbon material, an infinite number of filament-shaped (worm-shaped) unit shapes were observed. The diameter of this filament was 20-30 nm. In the transmission electron microscope observation, a structure close to (2) in FIG. 13 was observed.

Example 3
In Example 1, the temperature was changed to 450 ° C. and the reaction time was changed to 6 hours, and nickelocene as a catalyst was further converted to nickel metal fine powder, metal cobalt fine powder, nickel metal-supported silica powder, nickel-supported alumina powder, and palladium-supported alumina powder. And nickel oxide powder, respectively, and attempted to prepare a nanocarbon material in the same manner as in Example 1. As a result, it was found that a filament-shaped nanocarbon was formed in each case.

Table 1 summarizes the pressure and yield during the synthesis and the diameter of the nanocarbon unit in the case of the above-mentioned catalysts in the case of the metal nickel fine powder, the metal cobalt fine powder, the nickel metal-supported silica powder, and the nickel oxide powder. The metal nickel particles used had a particle size of 0.5 to 1.0 μm and a specific surface area of 1.5 to ^2.5 m ² / g. The amount of nickel supported in the used nickel metal-supported silica powder was 70% by weight, the primary particle size was 0.01 to 0.02 μm, the secondary particle size was about 20 μm, and the specific surface area was 30 to 40 m ² / g. Met. The primary particle size of the nickel-supported alumina powder used was 0.1 μm, and the secondary particle size was 5 to 10 μm. The primary particle diameter of the used palladium-supported alumina powder was 0.01 μm, and the secondary particle diameter was 20 to 30 μm. Only when cobalt metal powder was used as the catalyst, the catalyst amount was 1 g.

  From the results in the above table, it was found that when nickel-supported silica having the smallest transition metal particles was used as the catalyst, a nanocarbon material having a filament unit having the smallest diameter was obtained. In the nanocarbon material synthesized using nickel oxide powder as a catalyst, the filament length of the unit was short, and the result of X-ray diffraction analysis showed that nickel oxide was reduced to metallic nickel. This suggests that the atmosphere during the reaction is a reducing atmosphere. As the components of the reducing atmosphere, hydrogen gas and carbon monoxide can be considered. Hydrogen gas will be generated by decomposition of the raw material. Carbon monoxide may be generated from the generated hydrogen and carbon dioxide, or may be generated by a reaction between oxygen remaining in the container and a raw material. Further, the generated carbon monoxide may be a raw material of the nanocarbon material.

  In addition, the filament-like nanocarbon unit grown from the metallic nickel particles having a large particle diameter was as thick as about 100 nm, and the microstructure was observed as a structure close to (3) in FIG.

Example 4
In Example 1, the synthesis of a nanocarbon material was attempted in the same manner as in Example 1 except that the ferrocene of the catalyst was replaced with metal iron fine particles. As a result, it was found that the same nanocarbon as the filamentous unit as in Example 1 was obtained.

  However, when the reaction temperature was 450 ° C., nanocarbon was not obtained, and the result of X-ray diffraction analysis showed that the metallic iron was changed to iron oxide.

Example 5
In Example 1, the temperature was changed to 450 ° C., the reaction time was changed to 6 hours, and the starting n-hexane was further changed to n-pentane, n-heptane, n-octane, n-nonane, n-decane, hexadecane, , 2,4-Trimethylpentane, cyclohexane, 1-hexene, and n-octene were replaced with the same operation as in Example 1 to synthesize a nanocarbon material. As a result, it was found that a nanocarbon material having the same unit shape as in Example 2 and having a filament shape was obtained.

  Table 2 summarizes the pressures and yields of the various raw materials during synthesis and the diameter of the nanocarbon unit.

Example 6
In Example 1, the temperature was changed to 450 ° C., the reaction time was changed to 6 hours, and the raw material n-hexane was changed to ethanol, 1-butanol, and hexanol, respectively. I tried to synthesize the material. As a result, it was found that a nanocarbon material having the same unit shape as in Example 2 and having a filament shape was obtained.

  Table 3 summarizes the pressures and yields during synthesis for the various raw materials.

  From the above results, it was found that the yield of nanocarbon material equivalent to that of n-hexane of hydrocarbon can be obtained from 1-butanol.

Example 7
In Example 1, the temperature was changed to 450 ° C., the reaction time was changed to 6 hours, and the catalyst prepared by the following preparation method was replaced with a reaction pressure of 20.9 MPa. A carbon material was prepared. Unlike the other examples, the shape of the obtained nanocarbon material was spherical from 1 to 3 μm in diameter by scanning electron microscope observation.

(Catalyst preparation)
A catalyst was prepared by the following operation.

(I): 7.08 g of cetyltrimethylammonium bromide as a surfactant was added to 63.72 g of toluene, heated to 70 ° C., and 0.1 g of nickel chloride NiCl ₂ .6H ₂ O was added and dissolved.

(II): While stirring the solution of the above (I) with a homogenizer, an aqueous solution of NaBH ₄ (having 0.0476 g of NaBH ₄ dissolved in 2.5 g of ion-exchanged water) was dropped and reacted.

  (III): The suspension obtained in the above (II) was centrifuged, further washed with toluene and acetone, centrifuged, the solvent was removed and dried to prepare a catalyst.

Example 8
In Example 1, the temperature was changed to 450 ° C., the reaction time was changed to 6 hours, liquid nitrogen was used instead of dry ice, and the reaction pressure was 2.4 MPa. Materials were prepared. Although the yield of the obtained nanocarbon material was as small as 0.01 g, the shape of the nanocarbon unit was filamentous as in Example 2 as a result of observation with a scanning electron microscope.

  Further, in Example 1, the temperature was changed to 450 ° C., the reaction time was changed to 6 hours, argon gas was used instead of dry ice, the reaction pressure was 7.5 MPa, and the other operations were the same as in the example. When an attempt was made to synthesize a nanocarbon material, a nanocarbon material similar to that of Example 2 was obtained in a small amount.

  Furthermore, in Example 1, the temperature was changed to 450 ° C., the reaction time was changed to 6 hours, and the reaction pressure was changed to 9.5 MPa, and the yield of the obtained nanocarbon material was 0.51 g.

  From the above results, (1) that the nanocarbon material is synthesized even at a pressure of about 2 MPa, (2) that carbon dioxide is better than nitrogen gas or argon gas as a medium from the viewpoint of the yield of the nanocarbon material, I understood. In addition, the above results suggest that carbon dioxide may function as a medium for promoting the synthesis reaction of nanocarbon, or may function as a raw material for synthesis of nanocarbon in combination with the reducing atmosphere generated during the reaction. It is.

Example 9
The synthesis of nanocarbon was performed using a reactor as shown in FIG.

  First, 0.2 g of a silica powder carrying 70% by weight of nickel metal as a catalyst is inserted into a high-temperature and high-pressure reaction vessel made of Hastelloy (Ni-Mo alloy) having a capacity of 95 ml, and the inside of the reaction vessel is evacuated by an exhaust device. After evacuation, 7.26 g of n-hexane and 11.26 g of carbon dioxide as raw materials were introduced into the reaction vessel. Next, the reaction vessel was heated to 450 ° C., the pressure in the reaction vessel was set to 19.0 MPa, and the reaction was performed for 6 hours. Then, the mixture was cooled to room temperature, the reaction vessel was opened, and the solid content was taken out and dried to obtain a reaction product.

  Furthermore, a reactive product was obtained by the same operation as the above, except that n-hexane as the raw material was changed to methane, ethane, propane, ethylene, and propylene, respectively.

  From the results of observation with a scanning electron microscope and a transmission electron microscope, the obtained reaction product was found to be a nanocarbon material composed of an innumerable filamentous unit similar to that in Example 2. The diameter of the filamentous unit of the obtained nanocarbon material was 20 to 80 nm when the raw material was ethylene, and 20 to 80 nm when the raw material was propylene.

  Table 4 summarizes the synthesis conditions and yields for the various raw materials.

  From the results in Table 4 above, it was found that in Example 9, the conversion from the raw material to nanocarbon was higher in the order of propylene, ethylene, and n-hexane. That is, in the production method of the present invention, it is considered that the unsaturated hydrocarbon is easily converted to the nanocarbon material of the filamentous unit. In this example, the effect of oxygen remaining in the reaction vessel was small, and the nickel-supported silica was more stable than nickelocene.

Example 10
0.2 g of ferrocene was introduced into a pressure-resistant container made of Hastelloy (Ni-Mo alloy) having an internal volume of 95 ml, and after degassing, 7.92 g of n-hexane was introduced and sealed, and the temperature was 800 ° C and the pressure was 2. The reaction was performed at 1 MPa for 2 hours. Then, the mixture was cooled to room temperature, the reaction vessel was opened, and the solid content was taken out and dried to obtain 0.314 g of a reaction product. Observation of the obtained product from a transmission electron microscope (TEM) photograph from FIG. 14 shows that the structure is a multi-layered carbon nanotube structure similar to (4) in FIG. 13 containing metal iron particles of the catalyst. Was.

Example 11
After introducing 0.2 g of ferrocene into a pressure-resistant container made of Hastelloy (Ni-Mo alloy) having an internal volume of 95 ml and degassing, 3.89 g of methane was introduced, sealed, and heated at a temperature of 800 ° C. and a pressure of 12.9 MPa. The reaction was performed for 10 minutes. Then, the mixture was cooled to room temperature, the reaction vessel was opened, and the solid content was taken out and dried to obtain 0.447 g of a reaction product. From observation of the obtained product by a scanning electron microscope (SEM) photograph shown in FIG. 15, countless filamentary nanocarbons having a diameter of 20 nm to 100 nm and a length of 30 μm to 100 μm were recognized. From observation by a transmission electron microscope (TEM), it was confirmed that the carbon nanotube was a multi-walled carbon nanotube.

  Next, the multi-walled carbon nanotube (nano carbon material) obtained by the above operation is pulverized by a ball mill, the pulverized carbon nanotube is dispersed by irradiating ultrasonic waves to isopropyl alcohol, and a stainless steel is electrophoresed by applying a DC electric field. A nanocarbon material layer was formed on the substrate, and the cathode shown in FIG. 7 was formed. Next, a field electron emission device having a device structure shown in FIG. 7 was assembled using an aluminum plate as the anode and a mica plate having a thickness of 150 μm as the spacer. An electric field was applied to the fabricated device in a vacuum chamber, and current-voltage characteristics of field emission were measured. As a result, it was found that the threshold voltage was less than 2 V / μm, and an electron emission current value approximately 30 times superior to that of a commercially available multi-walled nanotube manufactured by Honjo Chemical was obtained.

Example 12
After 0.2 g of ferrocene was introduced into a pressure-resistant container made of Hastelloy (Ni-Mo alloy) having an internal volume of 95 ml and degassed, 9.34 g of propylene was introduced and sealed, and the pressure was increased at 800 ° C. under a pressure of 2.2 MPa. Allowed to react for minutes. Then, the mixture was cooled to room temperature, the reaction vessel was opened, and the solid content was taken out and dried to obtain 0.443 g of a reaction product. From the observation of the scanning electron microscope (SEM) photograph of FIG. 16 of the obtained product, countless filamentary nanocarbons having a diameter of 40 nm or less were found. From observation by a transmission electron microscope (TEM), it was confirmed that the carbon nanotube was a multi-walled carbon nanotube.

Example 13
5.99 g of nitrogen in addition to 3.89 g of methane and 0.2 g of ferrocene were introduced into a degassed 95-ml Hastelloy (Ni-Mo alloy) pressure-resistant container, which was then sealed. The reaction was performed at 16.0 MPa for 10 minutes. Then, the reaction product was cooled to room temperature, the reaction vessel was opened, and the solid content was taken out and dried to obtain a reactive product having a weight 1.3 times that of Example 11 described above. From observation of a scanning electron microscope (SEM) photograph of the obtained product, countless filamentary nanocarbons having a diameter of about 100 nm were found. Compared to the nanocarbon of Example 11, the diameter was larger and more uniform, and the length was shorter.

Comparative Example 1
In Example 1, the reaction temperature was changed to 90 ° C., the reaction pressure was changed to 15 MPa, and the other operations were performed in the same manner as in Example 1 to synthesize a nanocarbon material.

  As a result, generation of a nanocarbon material similar to that of Example 1 was not recognized.

Comparative Example 2
In Example 1, an attempt was made to synthesize a nanocarbon material by changing the reaction pressure to 1 MPa and performing the same operation as in Example 2 except for the above.

  As a result, generation of a nanocarbon material similar to that of Example 1 was not recognized.

Comparative Example 3
In Example 1, synthesis of a nanocarbon material was attempted by performing the same operation as in Example 1 except that nickelocene was not introduced into the reaction vessel.

  As a result, generation of a nanocarbon material similar to that of Example 1 was not recognized.

Comparative Example 4
In Example 1, an attempt was made to synthesize a nanocarbon material by performing the same operation as in Example 1 except that the raw material was changed to methanol.

  As a result, generation of a nanocarbon material similar to that of Example 1 was not recognized.

It is a flowchart which shows an example of the manufacturing method of the nanocarbon material of this invention. It is an example of the schematic diagram of the manufacturing apparatus used for manufacture of the nanocarbon material of this invention. It is an example of the schematic diagram of the continuous type manufacturing apparatus used for manufacture of the nanocarbon material of this invention. FIG. 1 is an example of a sectional configuration diagram of a lithium secondary battery. 1 is an example of a schematic cross-sectional configuration diagram of a lithium secondary battery electrode structure formed from a nanocarbon material. 1 is an example of a schematic cross-sectional configuration diagram of a main part of an FED using a nanocarbon material. FIG. 3 is an example of a schematic cross-sectional configuration diagram of an element for confirming field emission of a nanocarbon material. It is an example of a schematic block diagram of the apparatus which measures the hydrogen storage performance of a nanocarbon material. 3 is an example of an image of the nanocarbon material prepared in Example 1 of the production method of the present invention, which is observed with a scanning electron microscope. 1 is an example of a low-magnification image of a nanocarbon material prepared in Example 1 of a production method of the present invention, observed with a transmission electron microscope. 3 is an example of a high-magnification image of a nanocarbon material prepared in Example 1 of the production method of the present invention, observed with a transmission electron microscope. FIG. 1 is an example of a schematic diagram of a supposed unit structure of a filamentous nanocarbon prepared by the production method of the present invention. It is an example of the kind of structure inferred from the transmission electron micrograph of the nanocarbon material prepared by the production method of the present invention. 13 is an example of a high-magnification image of a nanocarbon material prepared in Example 10 of the production method of the present invention, observed with a transmission electron microscope. It is an example of the image observed by the scanning electron microscope of the nanocarbon material prepared in Example 11 of the production method of the present invention. 13 is an example of an image of a nanocarbon material prepared in Example 12 of the production method of the present invention, observed by a scanning electron microscope.

Explanation of reference numerals

Reference Signs List 200 High-temperature high-pressure reaction vessel 201 Raw material or medium 202 Catalyst 203 Heating device 204 Raw material storage container 205 Medium storage container 206 Pressure gauge 207 Safety valve 208 Exhaust device 209 Raw material or medium supply pipe 210 Exhaust pipe 211 Stirring mechanism 300 High-temperature high-pressure reactor 301 Product Separator 302 Raw material recovery / purification tower 303 Compressor 304 Raw material 305 Catalyst 306 Medium 307 Product (nanocarbon)
401 Negative electrode 402 Ion conductor 403 Positive electrode 404 Negative terminal 405 Positive terminal 406 Battery housing (container)
Reference Signs List 500 current collector 501 nanocarbon material powder 502 binder 503 conductive auxiliary material 504 active material layer 505 electrode structure (negative electrode)
600, 700 Insulating substrate 601, 701 Back electrode (cathode electrode)
602,702 Nano carbon material layer (cathode)
603,703 Insulating spacer (partition)
604 phosphor layer 605 transparent electrode (anode)
606 Surface mask 607 Transparent surface material (glass plate)
704 Anode electrode 705 Cathode lead 706 Anode lead 800 Hydrogen cylinder 801 Hydrogen storage container 802 Nanocarbon material filled container 803 Temperature controller 804 Vacuum pump 805 Pressure gauge 806 Vacuum gauge 807 Pressure regulating valve 808, 809, 810, 811, 812, 813 Open / close valve

Claims (25)

A raw material that is one or more compounds selected from alcohols in which the atomic ratio of the carbon atom to the chain saturated hydrocarbon, the chain unsaturated hydrocarbon, the cyclic saturated hydrocarbon, and the oxygen contained is 2.0 or more,
In the presence of a catalyst comprising one or more substances selected from transition metal element-containing substances, alumina, silica and silicon carbide,
A method for producing a nanocarbon material, comprising a step of converting the raw material into a supercritical fluid or a subcritical fluid in a temperature range of 100 to 800 ° C. and a pressure of 0.2 MPa to 60 MPa. Chain saturated hydrocarbons, chain unsaturated hydrocarbons, cyclic saturated hydrocarbons and at least one kind of raw material selected from alcohols having an atomic ratio of contained carbon to contained oxygen of 2.0 or more,
Adding an auxiliary (reaction accelerating medium) for promoting a nanocarbon generation reaction to a catalyst comprising one or more substances selected from transition metal element-containing substances, alumina, silica, and silicon carbide;
A temperature range of 100 to 800 ° C. and a pressure of 0.2 MPa to 60 MPa, at least a step in which the reaction promoting medium is brought into a supercritical fluid or a subcritical fluid and brought into contact with the raw material. Production method.   The reaction promoting medium is a solvent that dissolves the raw material, a solvent that dissolves the catalyst, water, helium, argon, nitrogen, hydrogen, carbon monoxide, nitrous oxide and at least one selected from ammonia. The method for producing a nanocarbon material according to claim 2, wherein:   Supercritical fluid or subcritical fluid In addition to the raw material and the catalyst, a solvent for dissolving the raw material, a solvent for dissolving the catalyst, water, helium, argon, nitrogen, hydrogen, carbon monoxide, nitrous oxide and ammonia The method for producing a nanocarbon material according to claim 1, wherein at least one selected from the group consisting of:   The method for producing a nanocarbon material according to claim 3, wherein the solvent of the raw material is at least one selected from carbon dioxide, an aromatic hydrocarbon, and an ether.   The method according to claim 1, wherein the pressure is in a range of 2 MPa to 40 MPa.   The method according to claim 1, wherein the temperature is in a range of 200 to 650 ° C. 4.   The method for producing a nanocarbon material according to claim 1, wherein a relative dielectric constant of the raw material at 25 ° C. is in a range of 1.5 to 25.0.   The method for producing a nanocarbon material according to claim 1, wherein the transition metal element-containing substance is at least one selected from transition metals and transition metal compounds.   10. The transition metal compound is at least one selected from transition metal sulfides, transition metal carbides, organic transition metal compounds, transition metal nitrides, transition metal salts and transition metal oxides. 3. The method for producing a nanocarbon material according to item 1.   The transition metal element of the transition metal or the transition metal compound is one or more elements selected from nickel, cobalt, iron, copper, silver, chromium, tungsten, molybdenum, titanium, ruthenium, rhodium and palladium. The method for producing a nanocarbon material according to claim 9, wherein   The process according to claim 1 or 2, wherein the step of converting the raw material into a supercritical fluid or a subcritical fluid or the step of contacting the raw material with a supercritical fluid or a subcritical fluid is performed in the presence of a catalyst and a surfactant. Manufacturing method of nanocarbon material.   A step of baking the reaction product obtained in the step of making the raw material a supercritical fluid or a subcritical fluid or in a step of bringing the raw material into contact with a supercritical fluid or a subcritical fluid at a temperature of 400 to 2800 ° C. The method for producing a nanocarbon material according to claim 1.   The method for producing a nanocarbon material according to claim 13, wherein the firing is performed at a temperature of 600 to 2200C.   The method for producing a nanocarbon material according to claim 13, wherein the firing is performed by firing at a temperature of 400 to 900 ° C, and further firing at a temperature of 900 to 2800 ° C.   The method for producing a nanocarbon material according to claim 13, wherein the baking is performed in at least one gas atmosphere selected from an argon gas, a helium gas, and a nitrogen gas.   3. The method for producing a nanocarbon material according to claim 1, wherein the shape of the unit constituting the obtained nanocarbon material is at least a shape selected from a filament shape (worm shape) and a tube shape.   The method for producing a nanocarbon material according to claim 17, wherein an average diameter of the obtained unit of the nanocarbon material is in a range of 4 nm to 400 nm.   The method for producing a nanocarbon material according to claim 18, wherein the obtained nanocarbon material is an aggregate of a plurality of units having an average diameter of 4 nm to 400 nm.   The method for producing a nanocarbon material according to claim 18, wherein the length of the unit of the obtained nanocarbon material is in a range of 100 nm to 100 m.   The method for producing a nanocarbon material according to claim 17, wherein the obtained nanocarbon material has a transition metal element in a unit or at a tip portion thereof.   22. The method for producing a nanocarbon material according to claim 21, wherein the obtained nanocarbon material has a transition metal, a transition metal oxide, a transition metal carbide, or a transition metal sulfide in a unit or at a tip thereof. .   The microstructure of the obtained nanocarbon is a hollow tube structure, and the carbon nanotubes or graphene sheets that are stacked in a megaphone shape in which the graphene sheet is inclined and wound with respect to the fiber axis are parallel to the fiber axis. 18. The method for producing a nanocarbon material according to claim 17, wherein the carbon nanotube is a single- or multiple-turned carbon nanotube.   The microstructure of the obtained nanocarbon is a columnar structure, and the platelet type graphite nanofibers in which the graphene sheets are stacked perpendicularly to the fiber axis, Hering in which the graphene sheets are stacked inclined with respect to the fiber axis 18. The method for producing a nanocarbon material according to claim 17, wherein the structure is selected from the group consisting of bone-shaped graphite nanofibers and filaments formed by laminating cup-shaped graphene sheets in the direction of the fiber axis. .   The method for producing a nanocarbon material according to claim 1, wherein the raw material is a liquid or a gas at normal temperature and normal pressure.

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