JP4972490B2 - Method for producing carbon fiber by combustion method - Google Patents

Method for producing carbon fiber by combustion method Download PDF

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JP4972490B2
JP4972490B2 JP2007209615A JP2007209615A JP4972490B2 JP 4972490 B2 JP4972490 B2 JP 4972490B2 JP 2007209615 A JP2007209615 A JP 2007209615A JP 2007209615 A JP2007209615 A JP 2007209615A JP 4972490 B2 JP4972490 B2 JP 4972490B2
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carbon fiber
carbon
flame
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JP2009041151A (en
JP2009041151A5 (en
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信夫 大澤
芳生 宮島
義紀 板谷
英二 神原
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昭和電工株式会社
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  The present invention relates to a method for producing carbon fiber by a combustion method using heat of a flame and combustion gas. More specifically, the present invention relates to a method for producing a large amount of carbon fiber having a small amount of particulate carbon, which is an impurity, in a high yield by a combustion method.

  Carbon fibers including carbon nanotubes and carbon nanofibers are attracting attention in many fields because they have excellent properties such as conductivity, thermal conductivity, heat resistance, and mechanical strength. These carbon fibers are mainly synthesized by a vapor phase method such as an arc discharge method, a laser evaporation method, or a chemical vapor deposition method (CVD method). Among these manufacturing methods, the CVD method is suitable for relatively large-scale synthesis and has been industrialized.

As a CVD method, for example, an organic compound such as benzene is used as a raw material, an organic transition metal compound such as ferrocene is used as a catalyst, these are introduced into a high-temperature reaction furnace together with a carrier gas, and carbon fiber is generated. It is disclosed in Document 1. According to this method, a carbon fiber having a high aspect ratio that is relatively thin and excellent in electrical conductivity and thermal conductivity can be obtained in a short reaction time. Further, Patent Document 2 discloses a production method for synthesizing carbon fibrils by reacting a solid catalyst and a carbon-containing gas at a temperature not higher than the thermal decomposition temperature of the carbon-containing gas for several hours in a reactor.
However, in these methods, it is necessary to heat a large amount of carrier gas to a high temperature of 1000 ° C. or higher in an external heating reactor. An externally heated reactor has poor thermal efficiency, tends to generate a temperature distribution in the furnace, and there is a limit to further increasing the size of the reactor.

Furthermore, as a method for producing carbon fiber by a vapor phase method, Patent Documents 6 and 7 describe that a carbon compound is introduced into a heating zone together with a mixed carrier gas composed of carbon monoxide, hydrogen, and, if necessary, carbon dioxide. A method for producing a carbon fiber by heating reaction in the temperature range of 600 to 1300 ° C. in the presence of a metal catalyst produced from a transition metal compound is disclosed. However, in this method, hydrogen is an essential component, and the produced carbon fiber has a diameter of 1 to 3 μm and only a carbon fiber having a small aspect ratio is obtained. Moreover, the catalyst precursor which can be used is also limited to the organic transition metal compound.
In Patent Document 8, a carbon compound is introduced into a heating zone together with a carrier gas comprising a converter exhaust gas and a hydrogen-containing gas, and a carbon fiber is produced by heating and reacting in a temperature range of 600 to 1300 ° C. in the presence of a metal catalyst. A method is disclosed. However, this method has poor versatility because the carrier gas is limited to the exhaust gas from the converter.

On the other hand, an application of a combustion method, which is one of the methods for producing carbon black, which is one of carbon materials, to the production of carbon fibers has been proposed. Since the combustion method uses the heat of the flame, the temperature distribution in the reactor becomes small, so the reactor may be easily upsized.
As a carbon fiber manufacturing method applying this combustion method, Patent Document 3 proposes a method of thermally decomposing hydrocarbons in a gas flame in the presence of a transition metal compound. However, in this method, most of the hydrocarbons supplied as a carbon source are burned with a gas flame, so that the yield of carbon fibers is low and the amount of particulate carbon which is an impurity increases.
Patent Document 4 proposes a method of thermally decomposing hydrocarbons outside a gas flame with a combustible fuel such as propane in the presence of a transition metal compound. However, even this method inevitably generates particulate carbon as an impurity.

Patent Document 5 discloses a method of manufacturing a carbon nanotube by fixing a catalyst in the vicinity of a flame against a premixed flame containing carbon. Examples of flame fuel include hydrocarbons such as acetylene and ethylene. However, even by this method, particulate carbon by-products cannot be avoided, and the catalyst must be fixed in the vicinity of the flame, making it difficult to obtain a continuous production method.
Non-Patent Document 1 discloses a method of generating a carbon nanotube on the surface of a metal wire by holding a metal wire serving as a catalyst over a flame using methane and air as fuel, and Non-Patent Document 2 discloses ethylene and air. A method of generating carbon nanotubes on the surface of a metal wire by disposing a metal wire serving as a catalyst for a predetermined time over a flame using as a fuel is disclosed. However, the methods described in Non-Patent Document 1 and Non-Patent Document 2 are not suitable for industrial production because only a very small amount of carbon fiber is obtained on the surface of the metal wire as a catalyst.
As described above, there has not been a method for economically producing a large amount of carbon fibers having a small amount of particulate carbon, which is an impurity, by a combustion method.

JP-A-60-54998 JP-T 62-500094 JP-A-61-282425 JP 63-182415 A JP 2005-247644 A Japanese Patent No. 2586054 Japanese Patent No. 2586055 Japanese Patent No.2521982 Chemical Physics Letters, 340 (2001) 237-241 Proceedings of the Combustion Institute, 30 (2005) 2553-2560

  An object of the present invention is to provide a method for producing a large amount of carbon fiber having a small amount of particulate carbon which is an impurity in a high yield by a combustion method.

As a result of intensive studies to achieve the above object, the present inventors have used a fuel, a carbon source, and a catalyst having a specific composition in a method for producing carbon fiber using the heat of combustion flame and combustion gas. As a result, it has been found that carbon fibers with a small amount of particulate carbon as impurities can be produced in a high yield, and the present invention has been completed.
That is, this invention relates to the manufacturing method of carbon fiber shown by following [1]-[27].
[1] A carbon source (B) is supplied to the outside of the flame in which the fuel (A) in which the moisture content in the combustion gas is 5% by volume or less is burned, and the temperature is 400 to 1500 ° C. in the presence of the catalyst (C). The manufacturing method of carbon fiber including the process made to react in the atmosphere of a range.
[2] Outside the flame in which the fuel (A) in which the moisture content in the combustion gas is 5% by volume or less is burned using the flame in which the fuel (A) is burned as a heat source and the combustion gas as a carrier gas A method for producing carbon fiber, comprising a step of contacting the carbon source (B) and the catalyst (C) in a temperature range of 400 to 1500 ° C.
[3] The method for producing carbon fiber according to [1] or [2], wherein the fuel (A) has a molar ratio H / C of hydrogen atoms to carbon atoms of less than 1.0.
[4] The method for producing carbon fiber according to [1] or [2], wherein the fuel (A) has a hydrogen / carbon atom molar ratio H / C of less than 0.1.
[5] The carbon fiber production method according to [1] or [2], wherein the fuel (A) is at least one selected from the group consisting of carbon monoxide, coal, and coke.
[6] The method for producing carbon fiber according to any one of [1] to [5], wherein the flame is a reducing flame.
[7] The carbon fiber manufacturing method according to any one of [1] to [6], wherein the flame is obtained by burning fuel (A) at an equivalence ratio of 1.5 to 4.0.
[8] The method for producing a carbon fiber according to any one of [1] to [7], further including a step of supplying hydrogen outside the flame.
[9] The method for producing a carbon fiber according to any one of [1] to [8], further including a step of supplying an inert gas outside the flame.

[10] The carbon source (B) is from methane, acetylene, ethane, ethylene, propane, propylene, butane, butadiene, benzene, toluene, xylene, naphthalene, phenanthrene, cyclopropane, cyclohexane, cyclohexene, methanol, ethanol, and isopropanol. The method for producing a carbon fiber according to any one of [1] to [9], which is at least one selected from the group consisting of:
[11] In any one of [1] to [10], the catalyst (C) is at least one selected from the group consisting of a simple substance of iron, cobalt, or nickel; and a compound of iron, cobalt, or nickel. The manufacturing method of carbon fiber of description.
[12] The method for producing a carbon fiber according to any one of [1] to [11], wherein the catalyst (C) is a solid catalyst (E) supported on a carrier (D).
[13] The carbon fiber according to [12], wherein the carrier (D) is at least one selected from the group consisting of carbon black, activated carbon, graphite, silica, alumina, titania, silica titania, calcium carbonate, and zeolite. Manufacturing method.
[14] The carbon fiber production method according to [13], wherein the carrier (D) has an average particle size of 100 nm or less.
[15] The method for producing a carbon fiber according to any one of [12] to [14], wherein the solid catalyst (E) has an average particle size of 200 μm or less.

[16] The method for producing a carbon fiber according to any one of [1] to [15], further including a step of supplying sulfur or the sulfur compound (F) outside the flame.
[17] The carbon fiber production method according to [16], wherein the sulfur compound (F) is an organic sulfur compound.
[18] The method for producing carbon fiber according to any one of [1] to [17], including a step of entraining the produced carbon fiber in an air stream containing combustion gas and collecting it at an outlet of the reaction apparatus. .
[19] The carbon fiber manufacturing method according to any one of [1] to [18], further including a step of incinerating the combustion gas.
[20] The method for producing carbon fiber according to any one of [1] to [19], which is a continuous production method.
[21] The method for producing a carbon fiber according to any one of [1] to [19], which is a batch production method.
[22] The method for producing a carbon fiber according to any one of [1] to [21], which is reacted in a fluidized bed.
[23] The method for producing a carbon fiber according to any one of [1] to [21], which is caused to react in the airflow layer.
[24] The carbon fiber production method according to [22] or [23], further using a flow aid.
[25] The method for producing a carbon fiber according to any one of [1] to [24], further comprising a step of heating at a temperature of 800 ° C. or higher to purify the carbon fiber.
[26] The method for producing a carbon fiber according to any one of [1] to [25], further including a step of graphitizing the carbon fiber by heating at a temperature of 2500 ° C. or higher.
[27] The carbon fiber production method according to any one of [1] to [26], wherein a solid carbon fiber having an average diameter of 5 to 300 nm and an average aspect ratio of 50 or more is produced.

  By the production method of the present invention, a large amount of carbon fibers with few particulate carbon as impurities can be obtained in a high yield. The obtained carbon fiber is called carbon nanotube or carbon nanofiber, and the diameter of the carbon fiber is usually 3.5 nm to 500 nm, and the aspect ratio (the length of the carbon fiber / the diameter of the carbon fiber) is 10 or more, The fiber shape is hollow and / or solid. The production method of the present invention is particularly suitable for production of solid carbon fibers having an average diameter of 5 to 300 nm and an average aspect ratio of 50 or more.

It is a figure which shows roughly the measuring apparatus used by the measurement examples 1-2 of this invention. It is a figure which shows roughly the carbon fiber manufacturing apparatus used in Examples 1-2 of this invention and the comparative example 1. FIG.

Explanation of symbols

1. ・ Quartz reaction tube (outer diameter 50mmφ x inner diameter 43mmφ x length 1500mm)
2 ・ ・ 1mmφZirconia beads (height 50mm)
3 ·· Flame 4 · · Trap 5 · · 100 mesh wire mesh · · Cold trap 7 · · Dry ice-acetone bath 8 · · Water trap 9 · · Water 10 · · Gas sampling valve 11 · · Afterburner 12 · · Quartz reaction tube (outer diameter 50 mmφ x inner diameter 43 mmφ x length 1500 mm)
13. Heat insulation material (glass wool)
14. ・ 1mmφZirconia beads (height 50mm)
15. Flame 16 ... Silicone electric furnace (length 600mm)
17. ・ R type thermocouple 18. ・ Vaporizer (200 ℃)
19. ・ R type thermocouple 20 ・ ・ Carbon fiber collecting part 21 ・ ・ 100 mesh wire mesh (SUS430)
··· Cold trap 23 · · Salt-ice water bath 24 · · Water trap 25 · · Water 26 · · Gas sampling valve 27 · · Afterburner

In the method for producing carbon fiber of the present invention, the carbon source (B) is supplied outside the flame in which the fuel (A) in which the moisture content in the combustion gas is 5% by volume or less is burned, and in the presence of the catalyst (C). It includes a step of reacting in an atmosphere in a temperature range of 400 to 1500 ° C.
Further, the carbon fiber production method of the present invention uses a flame in which the fuel (A) is burned as a heat source and a combustion gas as a carrier gas, so that the amount of water in the combustion gas is 5% by volume or less. It includes a step of bringing the carbon source (B) and the catalyst (C) into contact in a temperature range of 400 to 1500 ° C. outside the flame in which (A) is burned.

  The fuel (A) used in the present invention has a small amount of water in the combustion gas, specifically, the amount of water in the combustion gas is 5% by volume or less. When a fuel with a moisture content in the combustion gas exceeding 5% by volume is used, the amount of carbon fiber produced is reduced, and particulate carbon is easily produced as a by-product.

  Examples of such fuel (A) include solid fuels such as coal, coke, activated carbon, carbon black, and graphite; liquid fuels such as light oil, kerosene, benzene, toluene, ethanol, and propanol; acetylene, ethylene, ethane, propane, Mention may be made of gaseous fuels such as propylene, butane, butene, butadiene and carbon monoxide. These fuels can be used singly or in combination of two or more if the water content in the combustion gas is 5% by volume or less.

  Among these, a fuel that has a small content of hydrogen atoms that cause generation of water during combustion or that does not contain hydrogen atoms is preferable. Specifically, the molar ratio of hydrogen atoms to carbon atoms is H. A fuel having a / C of less than 1.0 is preferred, and a fuel having a hydrogen / carbon atom molar ratio H / C of less than 0.1 is particularly preferred. A particularly preferable fuel having a low hydrogen atom content includes at least one fuel selected from the group consisting of carbon monoxide, coal, and coke.

  The amount of moisture in the combustion gas is determined by condensing the moisture in the combustion gas with a cold trap and collecting the water and measuring its mass. Analyze the composition and obtain from the analysis results.

  The flame used for this invention is a combustion flame produced | generated by mixing the said fuel (A) and the combustion support gas containing oxygen, and making it burn. In order to adjust the size of the flame and stabilize the flame, an inert gas such as nitrogen, helium or argon can be arbitrarily mixed with the fuel as a diluent gas. As the dilution gas, nitrogen is economical and preferable. The mixing ratio of the fuel (A), the combustion-supporting gas, and the dilution gas can be arbitrarily set depending on the desired flame size and temperature.

  The flame becomes an oxidation flame or a reduction flame depending on the amount of the combustion-supporting gas. In the present invention, a reducing flame is preferably used. In order to obtain a reducing flame, the equivalent ratio (theoretical air amount / supply air amount) is preferably 1.0 or more, and more preferably 1.5 to 4.0. The theoretical air amount is the amount of air consumed when the fuel is completely burned. When the equivalent ratio (theoretical air amount / supply air amount) is less than 1.0, an oxidizing atmosphere is obtained, the catalyst is easily oxidized, and carbon fibers tend to be hardly obtained. On the other hand, if the equivalence ratio is too large, the flame becomes unstable and the flame temperature tends not to rise. The upper limit of the equivalent ratio varies depending on the scale of the combustion facility and the amount of heat released. If the scale of the combustion facility is large and the heat dissipation of the flame is small, the flame can be stabilized even if the equivalent ratio is increased, and a sufficient temperature may be obtained for producing the carbon fiber.

In the present invention, a flame is generated in the reaction furnace, and the carbon source (B) is supplied outside the flame. The burner and the combustion device that generate the flame are not particularly limited by the structure and the like. It can be set appropriately depending on the size of the reaction furnace and the required temperature, such as air-fuel mixture combustion and diffusion combustion.
The flame may be ejected upward, may be ejected downward, or may be ejected horizontally depending on the structure of the reactor. In addition, the range of a flame is a range which can confirm a flame with eyes.

Examples of the carbon source (B) used in the present invention include aliphatic saturated hydrocarbons such as methane, ethane, propane, n-butane, n-pentane, and n-hexane; acetylene, ethylene, propylene, 1-butene, Aliphatic unsaturated hydrocarbons such as 2-butene and 1,3-butadiene; alcohols such as methanol, ethanol, isopropanol and 1-butanol; aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene and phenanthrene; cyclopropane , Cyclobutane, cyclopentane, cyclohexane, cyclohexene, cycloheptane, and other alicyclic hydrocarbons; other organic compounds such as acetone, methyl ethyl ketone, ethylene glycol, propylene glycol, acetic acid, and ethyl acetate. These can be used alone or in admixture of two or more. Among these, methane, acetylene, ethane, ethylene, propane, propylene, butane, butadiene, benzene, toluene, xylene, naphthalene, phenanthrene, cyclopropane, cyclohexane, cyclohexene, methanol, ethanol, and isopropanol are particularly preferable.
The carbon source is preferably supplied in a gaseous state. It is preferable to supply a liquid or solid carbon source after it is vaporized at room temperature. In supplying the carbon source, an inert gas such as nitrogen and / or hydrogen can be supplied outside the flame.

  The catalyst (C) used in the present invention is not particularly limited as long as it is a substance that promotes the growth of carbon fibers. Examples of such a catalyst include at least one metal simple substance selected from the group consisting of elements belonging to Groups 2 to 15 of the periodic table. Of these, at least one elemental metal selected from the group consisting of elements belonging to Groups 3, 5, 6, 8, 9, and 10 is preferable, and iron, nickel, and cobalt are particularly preferable. In addition, compounds and alloys containing these elements can also be used as catalysts. As such a compound, ferrocene is particularly preferable.

  The catalyst (C) can be used as a solid catalyst (E) in which a catalyst precursor compound is supported on an appropriate carrier (D). As the carrier (D), carbon materials such as carbon black, activated carbon and graphite; inorganic compounds such as silica, alumina, silica alumina, titania, silica titania, magnesia, zirconia, calcium carbonate and zeolite can be used. These can be used alone or in combination of two or more. Among these, carbon black, graphite, alumina, titania, silica titania, calcium carbonate, and zeolite are preferable from the viewpoint of carbon fiber yield. In addition, a carrier having a particle size of any size can be used, but a carrier having an average particle size of 100 nm or less is preferable. When a solid catalyst is prepared by an impregnation method using such a support, the supported catalyst metal can be dispersed with a relatively small diameter, so that the carbon fiber produced using the impregnation method solid catalyst has a small diameter and an aspect ratio. The ratio becomes high. In addition, an average particle diameter is an average diameter which multiplied the weight of the mass fraction.

As the catalyst precursor compound, nitrates, sulfates, chlorides, acetates, organometallic compounds and the like of catalytic metal elements can be used. The supporting method is not particularly limited, and examples thereof include a method of preparing by a conventional method such as an impregnation method. The amount of the catalytic metal supported in the solid catalyst is preferably 5 to 30% by mass in terms of catalytic metal from the viewpoint of reaction efficiency.
Solid catalysts include powders, granules, pellets and the like, but are not particularly limited depending on the shape. The solid catalyst preferably has an average particle size of 200 μm or less, more preferably 100 μm or less. When the average particle diameter exceeds 200 μm, the reaction in the airflow layer tends to be difficult, and the mechanical strength tends to be low when the resin is mixed with the resin without removing the carrier from the synthesized carbon fiber. There is. A solid catalyst having an average particle size of 200 μm or less can be suitably used for production of carbon fibers using an air flow layer. A solid catalyst having an average particle size of 200 μm or less can be achieved by pulverizing and then sieving with an appropriate mesh. In addition, an average particle diameter is an average diameter which multiplied the weight of the mass fraction.
The amount of catalyst used can be appropriately set according to the size of the reactor, the type of carbon source, the type of catalyst, and the like.

  In the present invention, sulfur or a sulfur compound (F) is preferably supplied out of the flame because it is effective in increasing the yield of carbon fibers. Examples of the sulfur compound include methyl thiol, ethyl thiol, 1-propane thiol, 1-butane thiol, 1-pentane thiol, 1-hexane thiol, thiophenol, benzyl mercaptan, methyl sulfide, methyl disulfide, thiophene, and carbon disulfide. Hydrogen sulfide can be used. Among these, organic sulfur compounds are preferable, and thiophene is particularly preferable. The amount of sulfur or sulfur compound (F) used is preferably in the range of 0.1 to 50 mass% with respect to the catalyst metal.

  The method for supplying the carbon source (B) to the outside of the flame using the fuel (A) is not particularly limited. For example, a carbon source, a catalyst, a sulfur compound, and the like may be supplied separately, or a carbon source, a catalyst, a sulfur compound, and the like may be mixed and supplied. When the carbon source (B) is supplied into the flame, many carbon sources (B) are burned, so that the amount of carbon fiber is reduced. In addition, the outside of a flame is a position away so that a carbon source etc. do not burn by a flame. The supply position is preferably above the flame. The supply amount can be adjusted as appropriate.

  The carbon fiber synthesis reaction of the present invention is preferably performed in a temperature range of 400 to 1500 ° C. However, the optimum reaction temperature varies depending on the type of carbon source used. For example, a reaction temperature of 900 to 1300 ° C. is preferable for a carbon source having a relatively high thermal stability such as benzene, and a reaction temperature of 500 to 700 ° C. for a carbon source having a relatively low thermal stability such as ethylene. A temperature is preferred, and a reaction temperature of 400 to 600 ° C. is preferred for acetylene.

  When an organometallic compound is used as the catalyst (C), the catalyst (C) is dissolved or dispersed in a liquid carbon source or an appropriate solvent, and is entrained with hydrogen or an inert gas, and then outside the flame in the reactor. Can be introduced. Further, when the catalyst (C) is a solid catalyst (E), for example, a stainless steel or ceramic net can be installed outside the combustion flame, and the solid catalyst can be installed thereon. It is also possible to make the fluidized bed by fluidizing the solid catalyst by adjusting the flow rate of the combustion gas. Furthermore, it can also be set as an airflow layer using the fine powder solid catalyst. When the solid catalyst is used as an air flow layer, it is preferable to use a solid catalyst having an average particle size of 200 μm or less, and it is particularly preferable to use a solid catalyst having an average particle size of 100 μm or less.

  When the reaction is carried out in a fluidized bed or a gas flow layer, a flow aid can be added for the purpose of stabilizing the fluidized state of the fluidized bed or the gas flow layer and preventing aggregation of the produced carbon fibers. As the flow aid, alumina, silica, zirconia, carbon black, graphite or the like having an average particle size of 1 μm or less can be mixed and used in the range of 0 to 200 parts by mass with respect to 100 parts by mass of the solid catalyst. . By using a flow aid, carbon fibers with less aggregation can be obtained. The product carbon fiber and the flow aid can be separated using a bulk specific gravity or a difference in particle size, if necessary.

  The synthesized carbon fiber is allowed to react in the reactor at a desired temperature for a desired time, and is floated and entrained at the outlet of the reactor together with the combustion gas of the flame, and can be recovered with an appropriate filter. it can. Moreover, since the combustion gas after recovering the carbon fiber contains combustibles, it can be burned by an afterburner and incinerated.

  The carbon fiber obtained by the production method of the present invention removes impurities such as tar by heat treatment at a temperature of 800 ° C. or higher for several minutes to several hours in an inert gas atmosphere such as helium gas or argon gas. Can be purified. In order to increase the crystallinity of the carbon fiber, the carbon fiber can be graphitized by heating at a temperature of 2500 ° C. or higher in an inert gas atmosphere such as helium gas or argon gas.

  The carbon fiber production method of the present invention can be carried out either batchwise or continuously. If necessary, the carbon fiber after the reaction is purified by heat treatment, including graphitization, continuous, or partially continuous. Can also be done.

The carbon fibers obtained by the production method of the present invention are called carbon nanotubes or carbon nanofibers, and the diameter of the carbon fibers is usually 3.5 nm to 500 nm, and the aspect ratio (the length of the carbon fibers / the diameter of the carbon fibers). Is 10 or more, and the fiber shape is hollow and / or solid.
The production method of the present invention is particularly suitable for production of solid carbon fibers having an average diameter of 5 to 300 nm and an average aspect ratio of 50 or more. The structure of the carbon fiber can be changed depending on the reaction conditions such as the carbon source, the type of the catalyst or support, the reaction temperature, and the like. For example, when carbon monoxide is used as a fuel and ferrocene is used as a catalyst, a solid carbon fiber having an average diameter of about 100 nm is obtained. Moreover, the carbon fiber of the branched structure can also be obtained.
Since the carbon fiber obtained by the production method of the present invention has high electrical conductivity, thermal conductivity, etc., it can be dispersed in a matrix of resin, metal, ceramics, etc. to obtain a composite material. And thermal conductivity can be improved. In particular, when blended with a resin to form a composite resin material, it exhibits high electrical conductivity and is suitable for a resin / carbon fiber composite material used for antistatic applications and the like. Moreover, when the carbon fiber obtained by the production method of the present invention is blended with a metal, the breaking strength can be improved.

  EXAMPLES Next, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these Examples.

(Fuel analysis)
FIG. 1 is a conceptual diagram of an apparatus for measuring the composition of combustion gas generated when fuel is burned. The reaction tube 1 is a quartz tube having an outer diameter of 50 mm, an inner diameter of 43 mm, and a length of 1500 mm. The bottom is filled with zirconia beads having a diameter of 1 mm up to a height of 50 mm from the bottom.
A mixed gas of fuel gas, oxygen (combustible gas) and nitrogen (diluted gas) having the formulation shown in Table 2 is supplied to the bottom of the reaction tube 1 to ignite the mixed gas that has passed through the zirconia beads, Flame 3 was burned. Combustion gas is discharged from the top of the reaction tube, solid matter such as soot is removed by the metal net of the trap 4, water is collected by the two cold traps 6, and can further pass through the water trap 8. The combustion gas that has passed through the water trap 8 can be incinerated with a burner 11 (industrial gas (manufactured by Wep Corporation): LPG) and released to the atmosphere.
The mass of the water collected in the cold trap is measured, the combustion gas is extracted with the valve 10, analyzed by gas chromatography under the conditions shown in Table 1, and the moisture in the combustion gas generated when the fuel is burned The amount was determined.

As a result, the combustion gas composition of Measurement Example 1 (equivalence ratio 3.10, carbon monoxide) was 60.5% by volume of carbon monoxide, 31.0% by volume of carbon dioxide, 8.5% by volume of nitrogen, and 0.1% of water. It was 0% by volume.
Combustion gas composition of Measurement Example 2 (equivalence ratio 2.27, methane) is methane 16.0 vol%, water 27.1 vol%, carbon dioxide 4.4 vol%, carbon monoxide 19.7 vol%, hydrogen They were 27.7 vol%, nitrogen 2.9 vol%, and ethylene 2.2 vol%.

Example 1
FIG. 2 is a conceptual diagram of the carbon fiber production apparatus used in Examples and Comparative Examples. The reaction tube 12 is a quartz tube having an outer diameter of 50 mm, an inner diameter of 43 mm, and a length of 1500 mm. The bottom is filled with zirconia beads having a diameter of 1 mm up to a height of 50 mm from the bottom. The reaction tube 12 is installed in an electric furnace 16. Since the desired reaction temperature was not reached by the flame heat alone, the reaction tube was supplementarily heated in an electric furnace. The temperature of the electric furnace was set so that the temperature at the center of the reaction tube was 900 ° C.
A mixed gas of carbon monoxide (fuel gas), oxygen (combustible gas), and nitrogen (diluted gas) shown in Table 3 is supplied to the bottom of the reaction tube 12, and the mixed gas that has passed through the zirconia beads The flame 15 was ignited and burned. The amount of water in this combustion gas was 0% by volume. Hydrogen was passed through the vaporizer 18 at 8.0 NL / min, introduced into the reactor 12, and supplied to the outside of the flame 15.

After the flame and temperature are stabilized, a mixture of 93.5% by mass of benzene as a carbon source, 5.0% by mass of ferrocene as a catalyst and 1.5% by mass of thiophene as a sulfur compound (benzene: special grade (manufactured by Junsei Kagaku)); Ferrocene: special grade (manufactured by Junsei Chemical Co., Ltd.); thiophene: special grade (manufactured by Tokyo Chemical Industry Co., Ltd.)) with a syringe pump at a rate of 0.1 mL / min. The reaction was carried out for 10 minutes outside the flame.
The product generated in the reaction tube 12 was entrained in the combustion gas and accumulated in the collection unit 20. The combustion gas that has passed through the collection unit 20 passes through two cold traps 22 and one water trap 24, and is finally incinerated with a burner 27 (industrial gas (manufactured by Wek Corporation): LPG). Released.
After completion of the reaction, supply of hydrogen and mixed gas was stopped, and the inside of the reactor was cooled to room temperature under a nitrogen gas stream. The product was collected from the collection part 20, the mass was measured, and the yield was determined. The yield of product was 8.9 kg / m 3 h. The yield (kg / m 3 h) was expressed as a unit volume of the reaction tube (volume of the reaction tube = 2177 cm 3 ), an amount obtained per unit time.
Moreover, the product was observed with SEM (scanning electron microscope). All of the product was carbon fiber. The carbon fiber was a solid fiber having an outer diameter of about 100 nm. The production conditions and results are summarized in Table 3.

Example 2
The reaction was carried out in the same manner as in Example 1 except that the composition and amount of the mixed gas, the composition and supply time of the mixed solution, and the amount of hydrogen were changed to the formulations shown in Table 3.
The yield of product was 3.1 kg / m 3 h. All of the product was carbon fiber. The carbon fiber was a solid fiber having an outer diameter of about 100 nm. The production conditions and results are summarized in Table 3.

Comparative Example 1
The reaction was carried out in the same manner as in Example 1 except that the composition and amount of the mixed gas, the composition and supply time of the mixed solution, and the amount of hydrogen were changed to the formulations shown in Table 3.
The yield of product was 6.7 kg / m 3 h. Most of the product was particulate material, and no carbon fiber was obtained. The production conditions and results are summarized in Table 3.

Claims (12)

  1.   An atmosphere in a temperature range of 400 to 1500 ° C. is supplied in the presence of the catalyst (C) by supplying the carbon source (B) outside the flame in which the fuel (A) in which the moisture content in the combustion gas is 5% by volume or less is burned. The manufacturing method of carbon fiber including the process made to react by.
  2.   Using the flame in which the fuel (A) is burned as a heat source and the combustion gas as a carrier gas, carbon outside the flame in which the fuel (A) in which the amount of water in the combustion gas is 5% by volume or less is burned. The manufacturing method of carbon fiber including the process which a source (B) and a catalyst (C) are made to contact in the temperature range of 400-1500 degreeC.
  3.   The method for producing carbon fiber according to claim 1 or 2, wherein the fuel (A) has a molar ratio H / C of hydrogen atoms to carbon atoms of less than 1.0.
  4.   Furthermore, the manufacturing method of the carbon fiber of any one of Claims 1-3 including the process of supplying hydrogen outside a flame.
  5.   Furthermore, the manufacturing method of the carbon fiber of any one of Claims 1-4 including the process of supplying an inert gas out of a flame.
  6.   Furthermore, the manufacturing method of the carbon fiber of any one of Claims 1-5 including the process of supplying sulfur or a sulfur compound (F) out of a flame.
  7.   Furthermore, the manufacturing method of the carbon fiber of any one of Claims 1-6 including the process of incinerating a combustion gas.
  8.   It is a continuous manufacturing method, The manufacturing method of the carbon fiber of any one of Claims 1-7.
  9.   It is a batch type manufacturing method, The manufacturing method of the carbon fiber of any one of Claims 1-7.
  10.   The manufacturing method of the carbon fiber of any one of Claims 1-7 made to react with a fluidized bed.
  11.   The manufacturing method of the carbon fiber of any one of Claims 1-7 made to react with an airflow layer.
  12.   Furthermore, the manufacturing method of the carbon fiber of Claim 10 or 11 which uses a flow aid.
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