JP2002088591A - Method for producing fine carbon fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fine and straight carbon fiber having 1 nm to 50 nm diameter by using an inexpensive catalyst in a high yield. SOLUTION: In this method for producing a fine carbon fiber, the method comprises (i) a thermal decomposition process for introducing a vapor-phase mixture composed of (a) a hydrocarbon, (b) a catalytic metal-containing organic complex, (c) sulfur or a sulfur compound and (d) hydrogen for a carrier into a reaction zone heated to a temperature to thermally decompose the catalytic metal-containing organic complex and the hydrocarbon and thermally decomposing the catalytic metal-containing organic complex and the hydrocarbon to form a fine carbon fiber, (ii) a thermal decomposition product discharging process, (iii) a cooling process for cooling the thermal decomposition product to a temperature lower than the decomposition temperature of the hydrocarbon and (iv) a separation process for separating the cooled product into the fine carbon fiber and an exhaust gas comprising hydrogen as a main component, the ratio of flow rate of the hydrocarbon to hydrogen and the reaction time of the hydrocarbon are controlled to form the fine carbon fiber having 1 nm to 50 nm average particle diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing fine carbon fibers using a catalyst and a method for producing hydrogen using the same.

[0002]

2. Description of the Related Art Carbon nanotubes (hereinafter simply referred to as "tubes"), one of fine carbon fibers, are found in cathode deposits formed by graphite arc plasma discharge. It is performed by a laser irradiation method, a synthesis method using a catalyst, or the like. The carbon nanotubes obtained by the arc plasma discharge method have a multilayer structure in which graphite sheets are stacked in a cylindrical shape with good linearity at a diameter of several nm to several tens of nm, an aspect ratio of 500 to thousands, and extremely excellent electrons. It is said to exhibit release properties and very good mechanical properties.
In addition, it is attracting attention as a medium for storing hydrogen. However, Patent 252604 which improved the arc plasma discharge method
In the automatic and continuous method using a rotating cathode disclosed in Japanese Patent Application Laid-Open No. 8-108, the production rate is 1 g / h per production apparatus.
To several g / h, which leaves a problem for mass production. The productivity of the laser irradiation method is even lower than that of the arc plasma discharge method. According to these methods, the productivity per day is several kilos or less depending on the productivity, equipment construction cost, and the amount of power consumption.
Implementation on an industrial scale of several tons has many problems. Synthesis using a catalyst is expected as an alternative to these methods from the following three points. (1) Carbon fibers can be obtained with high yield. (2) Large-scale production enables mass production. (3) Inexpensive equipment construction cost As a synthesis method using a catalyst, for example, a method of suspending ultrafine powder in a hydrocarbon pyrolysis zone (Patent 1400)
271), a method of heating a mixed gas of a gas of a hydrocarbon compound, a gas of an organometallic compound, and a carrier gas (Japanese Patent No. 1532575), heating fine droplets of a transition metal or an organic compound containing the compound. A method of reacting while spraying toward the furnace wall to generate carbon fibers on the furnace wall and intermittently scraping the carbon fiber (Japanese Patent No. 2778434)
No.). However, since all of these methods mainly use carbonized fiber as a reinforcing agent for a composite material, the diameter of a tube to be developed is from 100 nm to several tens of μm, and there is cancer, bending, or branching. And does not have a multilayer cylindrical structure as obtained by the arc method. Japanese Patent No. 1532575 discloses a length of 0.2 μm to 2000 μm and a diameter of 0.05 μm to 10 μm.
It is disclosed that a short carbon fiber having a constant aspect ratio in the range of μm is continuously produced in high yield. In this method, the length of the tube is approximately proportional to the residence time. The size and shape of the tube obtained by the conventional chemical synthesis method did not pose a particular problem with respect to the demand as a reinforcing agent for the composite material. However, as a current electronic material such as an electron emission material, a tube having a large diameter and a bent shape has a structural problem. As described above, it is clear that the carbon fiber obtained by the chemical synthesis method of the existing technology is inferior in mechanical properties and electron emission to the carbon nanotube obtained by the arc plasma discharge method.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the conventional chemical synthesis method using a catalyst, and has the following objects. (1) Fine carbon fibers with good linearity can be obtained in high yield using an inexpensive catalyst. (2) A fine carbon fiber having a diameter of 1 nm to 50 nm is obtained.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have completed the present invention. That is, according to the present invention, in a method for producing fine carbon fibers, (i) (a) a hydrocarbon, (b) a catalytic metal organic complex, (c) sulfur or a sulfur compound, and (d) hydrogen for a carrier. A gas phase mixture is introduced into a reaction zone heated to a temperature at which the catalytic metal organic complex and the hydrocarbon are thermally decomposed to thermally decompose the catalytic metal organic complex and the hydrocarbon to form fine carbon fibers. A cracking step, (ii) a pyrolysis product discharging step of discharging a pyrolysis product containing fine carbon fibers generated in the pyrolysis step from the reaction zone, and (iii) a pyrolysis product discharged from the reaction zone. (Iv) a cooling step of cooling the mixture to a temperature lower than the decomposition temperature of the hydrocarbon; and (iv) a separation step of separating the cooling product obtained in the cooling step into fine carbon fibers and an exhaust gas containing hydrogen as a main component. , In the reaction zone A fine carbon fiber having an average diameter in the range of 1 nm to 50 nm by controlling the flow ratio of hydrocarbon to hydrogen and the reaction time of the hydrocarbon in the method. . Further, according to the present invention, in the method for producing fine carbon fibers, (i) (a) a hydrocarbon, (b) a catalyst metal organic complex, (c) sulfur or a sulfur compound, and (d)
A catalytic metal-organic complex pyrolysis step in which a gas-phase mixture of carrier hydrogen is introduced into the reaction zone to thermally decompose the catalytic metal-organic complex exclusively; and (ii) heat containing ultrafine metal particles generated in the thermal decomposition step. A hydrocarbon pyrolysis step in which the hydrocarbon is exclusively pyrolyzed to generate fine carbon fibers using the decomposition product as a catalyst, and (iii) a pyrolysis product containing the fine carbon fibers obtained in the hydrocarbon pyrolysis step. A step of discharging a pyrolysis product discharged from the reaction zone, (iv) a cooling step of cooling the pyrolysis product discharged from the reaction zone to a temperature lower than a decomposition temperature of the hydrocarbon, and (v) a cooling step. Separating the cooling product obtained in the above into fine carbon fibers and an exhaust gas containing hydrogen as a main component, comprising: a flow rate ratio of hydrocarbons and hydrogen in the reaction zone and a reaction time of the hydrocarbons. Control the average diameter Method for producing fine carbon fibers, characterized in that to produce a fine carbon fiber in the range of nm~50nm is provided. Further, according to the present invention, there is provided a method for producing hydrogen, comprising removing impurities from at least a part of an exhaust gas containing hydrogen as a main component obtained in the separation step of the method. Furthermore, according to the present invention, there is provided a method for producing fine graphite fibers, wherein the fine carbon fibers obtained by the above method are heat-treated at 1000 to 3000 ° C. in an inert gas atmosphere.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The term "fine carbon fibers" used herein means hollow carbon fibers having an average diameter in the range of 1 nm to 50 nm, and includes carbon nanotubes. In addition, “straight” with respect to the fine carbon fiber means that it does not have a bending point or a bending point, and has no branch or nodule.

[0006] The hydrocarbon used as a carbon raw material in the present invention is not particularly limited as long as it can be carbonized at a high temperature. These include methane, ethane, propane,
Saturated hydrocarbons such as butane, hexane and cyclohexane;
Unsaturated hydrocarbons such as ethylene, propylene, butene, and isobutene; acetylene-based compounds such as acetylene; aromatic hydrocarbons such as benzene, toluene, xylene, and naphthalene; Etc. are included. Furthermore, liquefied coal and coal are also included. In the present invention, ease of handling, economy,
From the viewpoint of the carbon content and the like, it is particularly preferable to use a liquid aromatic hydrocarbon having a boiling point of 80 to 200 ° C, for example, benzene, toluene, xylene, or a mixture thereof.

The catalyst metal organic complex used in the present invention is not particularly limited as long as it can be vaporized by heating.
As the catalytic metal in this catalytic metal organic complex, 3d
Any transition metal having an orbit may be used, and there is no particular limitation. Such metals include Fe, Co, Ni, C
u, Mo, etc., and in particular, Fe, Co, Ni
Are preferred. In the present invention, it is preferable to use a liquid catalytic metal organic complex having a boiling point of 50 to 400 ° C, preferably 50 to 200 ° C, because of its easy handling.
In the present invention, it is particularly preferable to use metal acetylacetonate such as iron acetylacetonate or metallocene such as ferrocene. The use ratio of the catalytic metal organic complex is such that the atomic ratio M / C of the metal M in the catalytic metal organic complex to the carbon in the raw material hydrocarbon is 7 × 10 ^{−3 to} 7 × 10 ⁻⁵ , preferably 3 ×.
It is a ratio of 10 ^{−3 to} 3 × 10 ⁻⁴ .

[0008] When the catalytic metal organic complex is thermally decomposed at a high temperature, an ultrafine catalytic metal is generated, which is present in a floating state in a flowing gas phase. Its particle size is usually 2
１５15 nm, preferably 5-10 nm. In addition, the suspended catalyst metal generated at a high temperature in this manner exists in the form of metal and / or metal carbide.

The sulfur compound used in the present invention is not particularly limited as long as it generates elemental sulfur by thermal decomposition. Such compounds include various sulfur compounds which are liquid at normal temperature, in addition to sulfur compounds which are gaseous at normal temperature, such as hydrogen sulfide and methyl mercaptan. Examples of the sulfur compound that is liquid at room temperature include ethyl mercaptan, propyl mercaptan, n-butyl mercaptan,
Aliphatic and aromatic mercaptan compounds such as benzyl mercaptan and phenyl mercaptan; methyl sulfide,
Alkyl sulfides such as ethyl sulfide and propyl sulfide; aryl sulfides such as benzyl sulfide and phenyl sulfide; and sulfur-containing cyclic compounds such as thiophene. In the present invention, it is preferable to use hydrogen sulfide or thiophene in terms of ease of handling, cost, and the like.

The use ratio of the elemental sulfur and the sulfur compound used in the present invention is such that the atomic ratio S / M with the metal M in the catalytic metal organic complex is 1 to 0.1 in terms of elemental sulfur. When the use ratio of the elemental sulfur and the sulfur compound is less than this range, the amount of the bent fine carbonized fiber increases, while when it is more than the above range, the diameter of the generated fine carbon fiber becomes larger than 50 nm. Show the trend.

In order to produce fine carbon fibers according to the present invention, first, in the gas phase mixture producing step, (a) a hydrocarbon, (b) a catalytic metal organic complex, (c) sulfur or a sulfur compound and (d) hydrogen A gaseous mixture consisting of In this gas phase mixture producing step, when a component that is liquid or solid at room temperature is contained in the component, the component is heated and vaporized. The hydrogen acts as a carrier gas, and its flow rate is a flow rate ratio of the raw material hydrocarbon [hydrocarbon] / [hydrogen] (mg
/ L) is 1 to 5000, preferably 3 to 500, more preferably 5 to 50. The gas-phase mixture is introduced into a reaction zone for thermally decomposing the catalytic metal-organic complex and the hydrocarbon or into a reaction zone for predominantly pyrolyzing the catalytic metal-organic complex. Can be entirely introduced into the gas phase mixture production step, but it is preferable to divide the hydrogen into two in a small-scale apparatus. When dividing hydrogen into two,
Part of this is introduced into this gas phase mixture production step, and the remainder is added to the produced gas phase mixture.

In order to preferably produce the gaseous mixture, (a) a hydrocarbon, (b) a catalytic metal-organic complex, (c)
The sulfur or sulfur compound and (d) hydrogen are introduced into a vaporizer where they are heated. In this case, the oil-soluble catalytic metal organic complex is preferably used by dissolving it in a liquid hydrocarbon (benzene, toluene, xylene, etc.). Also, liquid sulfur compounds such as thiophene, solid sulfur, etc.
It is preferable to use it by dissolving it in a liquid hydrocarbon. When a gaseous sulfur compound such as hydrogen sulfide is used at room temperature as the sulfur compound, it is preferable to use the gaseous sulfur compound by mixing it with hydrogen. The vaporizer may be any one having a mechanism for heating the introduced liquid or solid and a gas discharging mechanism for discharging the vaporized gas (gas), and a conventionally known one is used.

[0013] The heating temperature in the gas phase mixture producing step is a temperature at which a liquid or a solid contained in the raw material component is heated and vaporized, and the raw material component may have a sufficient vapor pressure. The upper limit temperature is a temperature at which the hydrocarbon or the catalytic metal organic complex does not decompose, that is, a temperature lower than the decomposition temperature of the hydrocarbon and the catalytic metal organic complex. For example, the heating temperature when using benzene-ferrocene-thiophene as a raw material is 80 to
The temperature is 400 ° C, preferably 100 to 150 ° C.

If the carrier hydrogen is divided into two parts, the gaseous mixture obtained as above is added with the remainder of the hydrogen divided into two parts and introduced into the reaction zone.
In this case, the temperature of the added hydrogen is 80 to 400 ° C.,
Preferably it is 100-150 degreeC. In the present invention, the gas-phase mixture is introduced into a reaction zone, where it is heated to perform thermal decomposition of the catalytic metal organic complex and thermal decomposition of the hydrocarbon. Thereby, fine carbon fibers are generated. When the catalytic metal-organic complex is thermally decomposed, a decomposition product containing ultrafine metal particles is generated, which acts as a catalyst for the production reaction of fine carbon fibers by the thermal decomposition of hydrocarbons, and the reaction is carried out. Promote.

When the gaseous mixture is thermally decomposed in the reaction zone, the gaseous mixture can be heated to a temperature at which both the catalytic metal organic complex and the hydrocarbon are thermally decomposed.
In this case, the reaction temperature is 700-1300 ° C.

In the present invention, when the gaseous phase mixture is supplied to the reaction zone, the amount of hydrocarbon contained in the whole supply is determined by the flow ratio of hydrocarbon to hydrogen [hydrocarbon] / [hydrogen].
(Mg / L) is 1 to 5000, preferably 1 to 10
The ratio is set to 0, more preferably 5 to 50.
If the proportion of the hydrocarbon is too large, it is difficult to make the diameter of the produced fine carbon fiber in the range of 1 to 50 nm, which is not preferable. On the other hand, when the proportion of hydrocarbons is less than the above range, the production efficiency of fine carbon fibers is undesirably deteriorated.

In the present invention, the residence time (reaction time) during which the hydrocarbons stay in the reaction zone where the thermal decomposition occurs is 0.1 to 0.1.
5 seconds, preferably 0.5 to 4 seconds.

The reaction zone in which the hydrocarbon is thermally decomposed includes, as described above, one reaction zone in which the reaction zone is temperature-controlled so that both the catalytic metal organic complex and the hydrocarbon are thermally decomposed. In that case, it means the reaction zone.

In the present invention, the [hydrocarbon] /
[Hydrogen] By controlling the flow ratio and the reaction time of the hydrocarbon, the average diameter of the obtained fine carbonized fiber is 1 to 50 nm.
Keep in the range.

In the present invention, in particular, [hydrocarbon] /
[Hydrogen] It is preferable to control the flow ratio (mg / L) in the range of 10 to 100 and control the reaction time of hydrocarbons to 4 seconds or less, whereby the average diameter is 1 to 50.
nm fine carbon fibers can be obtained with high yield.

The pyrolysis product containing fine carbon fibers obtained as described above is discharged from the reaction zone to a temperature at which pyrolysis of hydrocarbons does not occur, usually 600 ° C. or less, preferably 200 ° C. Thereafter, it is more preferably cooled to 40 ° C. or less, and separated into fine carbon fibers and exhaust gas. As the separation device in this case, various devices generally used for separating gas and solid, such as a bag filter and a wire mesh, can be used. In order to prevent clogging, it is also effective to bring a brush into contact with the surface of a rotary drum-shaped filter to scrape off deposits.

The exhaust gas after separating the fine carbon fibers from the pyrolysis product contains hydrogen produced by the pyrolysis of hydrocarbons, and contains hydrogen as a main component. The hydrogen concentration is 95 to 99. 0.5 mol%, usually 98 to 99.5 mol%. The impurities contained in the exhaust gas include sulfur compounds, pyrolysis hydrocarbon gas, unreacted substances, etc., and their concentrations are extremely low.

In the present invention, high-purity hydrogen can be advantageously produced by separating and removing impurities contained in exhaust gas. In this case, as a method for removing impurities from hydrogen, a conventionally known method is used. For example, a method of contacting the exhaust gas with a liquid such as water, acidic water, or an organic solvent to remove impurities in the exhaust gas into the liquid, an adsorbent (activated carbon, zeolite, silica, alumina, silica-alumina, magnesia, etc.) A method in which impurities in exhaust gas are adsorbed by the adsorbent to remove the impurities in the exhaust gas by flowing through an adsorption column filled with the porous substance, and a method using a separation membrane. High-purity hydrogen can be obtained as described above, and this hydrogen can be used for various purposes as industrial hydrogen. In the present invention, it is preferable that part of the carrier gas is circulated and used as the carrier gas.

Further, in the present invention, a part of the exhaust gas can be circulated and used as the carrier hydrogen gas in the gas-phase mixture generation step without performing a special purification treatment.

The reactor used in the present invention may be of a tube type or a tank type. In addition, as the vaporizer, a part of the reactor, for example, a former part (inlet part) of a reaction tube can be used. A vertical reactor can be effectively used, but a horizontal reactor may be used.

The fine carbon fiber obtained as described above has a hollow structure and is "straight" in shape. Usually, its average diameter is 1-50n
m, the average length of which is 1 to 50 μm.

Such a fine carbon fiber can be heat-treated at 1000 to 3000 ° C. in an inert gas atmosphere to obtain a fine carbon fiber. Also, 25
By heating to 00 to 3000 ° C, preferably 2800 to 3000 ° C, it can be graphitized to obtain fine carbon fibers. The heat treatment time is 0.5 to 2 hours, preferably 1 to 2 hours.

Next, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a flow sheet 1 for implementing the method of the present invention.
Here is an example. In the figure, 1 is a vaporizer, 2 is a reaction tube, 3 is a first heating furnace, 4 is a second heating furnace, 5 is a third heating furnace, 6 is a collector,
7 indicates a filter, and 8 indicates a header.

In order to produce fine carbon fibers according to the flow sheet shown in FIG. 1, a hydrocarbon (benzene), a catalytic metal organic complex (ferrocene) and a sulfur compound (thiophene) are introduced into a vaporizer 1 from a line 11. In addition, a part of hydrogen as a carrier gas is introduced into the vaporizer 1 through the lines 12, 13, the mass flow controller 14, and the line 15. The vaporizer 1 is maintained at a temperature of about 100 ° C. so that benzene, ferrocene and thiophene introduced through the line 11 are vaporized. The temperature of hydrogen supplied to the vaporizer 1 via the line 15 is about 25 ° C. The gas-phase mixture obtained in the vaporizer 1 is introduced into the reaction tube 2. In this case, the remaining hydrogen having a temperature of about 25 ° C. is introduced into the reaction tube 2 through the line 18 and mixed with the gas-phase mixture. Is done.

The benzene, ferrocene,
The gas phase reaction feed composed of thiophene and hydrogen passes through reaction tubes 2 through reaction zones a, b and c formed by heating furnaces 3, 4 and 5. The temperature (average temperature) of the reaction zones a, b and c is usually about 1200 ° C., and the gaseous phase reaction feed first passes through the reaction zones a, b and c by the pyrolysis of ferrocene. The formation of the iron ultrafine particle catalyst is followed by the thermal decomposition of benzene and the formation of fine carbon fibers. In the present invention, a plurality of reaction zones (2-
5, and preferably 2 to 4), it can be constituted by a single heating furnace.

The fine carbon fibers, hydrogen and pyrolytic hydrocarbon gas obtained from the reaction tube 2 as described above are introduced into a collector 6 where a solid and a gas are separated by a filter 7 installed therein. Separated. That is, the hydrogen and the pyrolysis hydrocarbon gas are discharged to the outside through the filter 7, and at this time, the fine carbon fibers contained in the pyrolysis product are separated from the gas by the filter. . The exhaust gas after the fine carbon fiber is separated is supplied to line 1
9. After being introduced into the header 8 through the three-way valve 20, it is discharged through the line 21. The lower portion of the header 8 is filled with water. This header is
Prevents air from flowing into the reactor.

The exhaust gas discharged from the header 8 is:
It is mainly composed of hydrogen, and its hydrogen concentration is usually 98 mol% or more. In addition, since hydrogen is generated by thermal decomposition of benzene, it increases when circulated and used as the carrier gas.

The exhaust gas discharged from the header 8 is refined to remove impurities contained therein,
High purity hydrogen can be obtained. This high-purity water can be used as industrial hydrogen, and part of it can be circulated and used as carrier gas hydrogen gas.

[0034]

Next, the present invention will be described in more detail by way of examples.

Example 1 Fine carbon fibers were produced using the vertical reactor shown in FIG. The experimental operation was performed after the entire system was sufficiently replaced with argon. The reaction tube 2 has an inner diameter of 26 mm, an outer diameter of 30 mm,
It is a quartz tube with a length of 1000 mm. Heating furnace height 600
mm, and is divided into three blocks 3, 4, and 5. Each block is 200 mm long and can measure and control the temperature, respectively. 0.1 L of argon during heating
/ Min, and after reaching the reaction temperature, argon was switched to hydrogen. As a reaction raw material, a mixture having a weight ratio of benzene: ferrocene: thiophene = 100: 4: 1 was supplied to a vaporizer 1 whose temperature was controlled at 100 ° C. by a micro feeder. The vaporized reaction material was diluted by supplying 0.05 L / min of hydrogen to the vaporizer from the mass flow controller (14). The supply amount of the reaction raw material thus obtained was 40, 80 or 120 μL / min, while the total hydrogen flow rate of the mass flow controllers (14) and (17) was 0.4, 0.6, 0.1 μm. The supply from the mass flow controller (17) was changed so as to be 8, 1.2 and 1.6 liter / min. The average temperature in the reaction tube 2 was as follows because the heating furnace 5 was not energized. (1) Reaction zone a: 1200 ° C. (2) Reaction zone b: 1200 ° C. (3) Reaction zone c: 550-650 ° C. The temperature of the collector 6 is about 25 ° C., and the exhaust gas discharged from the header Is about 25 ° C. The results of the experiments performed as described above are shown in Table 1 and FIG.

[0036]

[Table 1] * Shows a comparative example.

The average reaction time (residence time) shown in Table 1 indicates the average time (second) during which benzene stays in the reaction zones a and b. This average reaction time can be adjusted by the amount of hydrogen supplied from the line 18, and as the amount of hydrogen supplied increases, the average reaction time becomes shorter. The benzene / hydrogen flow ratio (mg / L) shown in Table 1 indicates the weight (mg) of benzene per liter of hydrogen supplied to the reaction zone, and the amount of benzene supplied to the vaporizer 1 from the line 11. And the hydrogen flow rate (liters / liter) supplied through line 16 mass flow controller 17 and line 18
Minutes) and can be adjusted. The density of benzene was calculated at 0.88 g / cm ³ . The diameter of the fine carbon fiber was observed with a microscope. The numbers shown in FIG. 2 indicate the average diameter (nm) of the generated fine carbon fibers.

As can be seen from Table 1, the average diameter (average outer diameter) of the fine carbon fibers obtained from the reaction zone is C ₆ H ₆ /
It can be adjusted by the H ₂ flow ratio and the average reaction time. By maintaining the C ₆ H ₆ / H ₂ ratio at 50 mg / L (g / m ³ ) or less and keeping the reaction time at 4 seconds or less. , 50 nm or less.

[0039]

According to the present invention, the average diameter is 1 to 50 n.
m, “straight” high-quality fine carbon fibers can be obtained with high yield.

[Brief description of the drawings]

FIG. 1 shows an example of a flow sheet for carrying out the method of the present invention.

FIG. 2 Flow rate ratio of benzene / hydrogen (mg / L), average reaction time (seconds), and average diameter (nm) of fine carbon fibers produced
FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vaporizer 2 Reaction tube 3, 4, 5 Heating furnace 6 Collector 7 Filter 8 Header

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Morio Yumura 1-1, Higashi, Tsukuba, Ibaraki Prefecture Within the Institute of Materials Science and Technology, Ministry of International Trade and Industry (72) Hiroki Ago, 1-1-1, Higashi, Tsukuba, Ibaraki Industrial Technology Institute of Materials Science and Technology (72) Inventor Toshiki Komatsu 1-1-1 Higashi, Tsukuba, Ibaraki Prefecture Institute of Materials Science and Technology (72) Inventor Toshio Morita 5-1 Okawacho, Kawasaki-ku, Kawasaki, Kawasaki, Kanagawa Showa Denko KK Production Technology Center (72) Inventor Hitoshi Inoue 5-1 Okawacho, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Showa Denko KK Production Technology Center F-term (reference) 4L037 CS03 FA03 FA04 PA09 PA13 PA21 PA28

Claims (11)

[Claims] 1. A method for producing fine carbon fibers, comprising:
(I) (a) a hydrocarbon, (b) a catalytic metal organic complex,
A gaseous mixture comprising (c) sulfur or a sulfur compound and (d) hydrogen for a carrier is introduced into a reaction zone heated to a temperature at which the catalytic metal organic complex and the hydrocarbon are thermally decomposed to form the catalytic metal organic complex. And a pyrolysis step of pyrolyzing the hydrocarbon to generate fine carbon fibers, and (ii) discharging a pyrolysis product including the fine carbon fibers generated in the pyrolysis step from the reaction zone. (Iii) a cooling step of cooling the pyrolysis product discharged from the reaction zone to a temperature lower than the decomposition temperature of the hydrocarbon, (iv) a cooling product obtained in the cooling step, A separation step of separating the fibers into an exhaust gas containing hydrogen as a main component, and controlling the flow ratio of hydrocarbons to hydrogen and the reaction time of hydrocarbons in the reaction zone so that the average diameter is from 1 nm to 50 nm.
A method for producing fine carbon fibers, comprising generating fine carbon fibers in the range of nm. 2. A method for producing fine carbon fibers, comprising:
(I) (a) a hydrocarbon, (b) a catalytic metal organic complex,
(C) introducing a gaseous mixture of sulfur or a sulfur compound and (d) hydrogen for carrier into a reaction zone to thermally decompose the catalytic metal-organic complex exclusively; A hydrocarbon pyrolysis step in which the hydrocarbon is pyrolyzed exclusively using the pyrolysis product containing ultrafine metal particles generated in the decomposition step as a catalyst to produce fine carbon fibers, (i
ii) a pyrolysis product discharging step of discharging a pyrolysis product containing fine carbon fibers obtained in the hydrocarbon pyrolysis step from the reaction zone, and (iv) a pyrolysis product discharged from the reaction zone. A cooling step of cooling to a temperature lower than the decomposition temperature of the hydrocarbon, (v) a cooling product obtained in the cooling step,
A separation step of separating into fine carbon fibers and an exhaust gas containing hydrogen as a main component, wherein the average diameter is 1 nm to 50 nm by controlling the flow rate ratio between hydrocarbon and hydrogen and the reaction time of hydrocarbon in the reaction zone. A method for producing fine carbon fibers, characterized by producing fine carbon fibers in the range of (1). 3. The method according to claim 1, wherein a flow ratio of hydrocarbon to hydrogen in the reaction zone is 1 to 5000. 4. The reaction time of a hydrocarbon in a reaction zone is 0.1 second to 5 seconds.
The production method according to any one of the above. 5. A reaction zone formed by a plurality of heating furnaces,
The method according to any one of claims 1 to 4, wherein the temperature of the reaction zone is from 700C to 1300C. 6. The hydrocarbon (a) has a boiling point of 80 ° C. to 200 ° C.
2. A liquid aromatic hydrocarbon of claim 1.
6. The method according to any one of claims 1 to 5, 7. The catalyst metal-organic complex (b) has a boiling point of 50 ° C. or less.
The method according to any one of claims 1 to 6, wherein the catalyst is a liquid catalytic metal organic complex at 400 ° C. 8. A method for producing hydrogen, comprising removing impurities from at least a part of an exhaust gas containing hydrogen as a main component obtained in the separation step of the production method according to claim 1. 9. An exhaust gas containing hydrogen as a main component has a hydrogen concentration of 9%.
The method for producing hydrogen according to claim 8, wherein the content is 5 mol% to 99.5 mol%. 10. The method for producing fine carbon fibers according to claim 1, wherein a part of the hydrogen obtained by the production method according to claim 8 is circulated and used as the carrier hydrogen according to any one of claims 1 to 7. . 11. The fine carbon fiber obtained by the method according to claim 1 is treated in an inert gas atmosphere for 10 minutes.
A method for producing fine carbon fibers, wherein the heat treatment is performed at a temperature of from 00C to 3000C.