JP7081252B2 - Manufacturing method and equipment for carbon structure - Google Patents

Description

The present invention relates to a method for producing a carbon structure and an apparatus for producing a carbon structure, and in particular, a method for producing a carbon structure using a chemical vapor phase growth method and a method for producing a carbon structure using a chemical vapor phase growth method. It is about the equipment to be manufactured.

Conventionally, a chemical vapor deposition (CVD) method is known as a method for producing a carbon structure such as carbon nanotubes (hereinafter, may be referred to as “CNT”) or graphene.

Here, in the production of a carbon structure using the CVD method, when a raw material gas containing carbon is brought into contact with a catalyst to form a carbon structure, a volatile organic compound (VOC) or a polycyclic fragrance is produced by a side reaction. Carbon-based by-products such as group hydrocarbons (PAHs) are produced. Then, the produced carbon-based by-product may adhere to the carbon structure and cause deterioration of product quality, or may block the exhaust pipe of the manufacturing apparatus and reduce the manufacturing efficiency.

Therefore, for example, in Patent Document 1, when a raw material gas is supplied onto a substrate having a catalyst on its surface to produce a CNT, the raw material gas after being used for the growth of the CNT, hydrogen, ammonia, oxygen, and the like are used. By mixing and reacting with a reaction gas such as ozone and water vapor, it is possible to prevent the formation of carbon solids as carbon-based by-products.

Japanese Unexamined Patent Publication No. 2011-219316

However, there is room for improvement in the above-mentioned conventional technique in that the formation of carbon-based by-products when producing a carbon structure by the CVD method is further suppressed.

Therefore, an object of the present invention is to provide a method and an apparatus for producing a carbon structure capable of sufficiently suppressing the formation of carbon-based by-products when the carbon structure is produced by the CVD method.

The present inventor has made diligent studies for the purpose of solving the above problems. Then, by using a reactive gas containing a compound having 1 or more and 5 or less carbon atoms having a hydroxy group and / or an aldehyde group, the present inventor can generate a carbon-based by-product in the production of a carbon structure by the CVD method. We have found that it is possible to sufficiently suppress the above, and have completed the present invention.

That is, the present invention aims to advantageously solve the above problems, and the method for producing a carbon structure of the present invention is a chemical vapor phase growth method in which a raw material gas containing a carbon compound is supplied to a catalyst. A step of growing a carbon structure by the above step (A) and a step of supplying a reactive gas containing a compound having a hydroxy group and / or an aldehyde group and having 1 or more and 5 or less carbon atoms to the reaction exhaust gas generated in the step (A). It is characterized by including (B). As described above, if a reactive gas containing a compound having 1 or more and 5 or less carbon atoms having a hydroxy group and / or an aldehyde group is supplied to the reaction exhaust gas generated in the step (A), a carbon-based by-product is produced. Can be sufficiently suppressed.

Further, the present invention has an object of advantageously solving the above-mentioned problems, and the apparatus for producing a carbon structure of the present invention supplies a raw material gas containing a carbon compound to a catalyst and uses a chemical vapor phase growth method. A reactive gas supply unit that supplies a reactive gas containing a compound having a hydroxy group and / or an aldehyde group and having 1 or more and 5 or less carbon atoms to a growth furnace for growing a carbon structure and the reaction exhaust gas generated in the growth furnace. It is characterized by having and. As described above, if the reactive gas supply unit is provided and the reactive gas containing a compound having a hydroxy group and / or an aldehyde group and having 1 or more and 5 or less carbon atoms is supplied to the reaction exhaust gas generated in the growth furnace, it is carbon-based. The formation of by-products can be sufficiently suppressed.

In the present invention, the compound is preferably a compound having 1 carbon atom and having a hydroxy group and / or an aldehyde group. This is because if a compound having one carbon atom is used, the formation of carbon-based by-products can be further suppressed.

Further, in the present invention, the compound is preferably at least one selected from the group consisting of methanol, formaldehyde and formic acid. This is because methanol, formaldehyde and formic acid are excellent in suppressing the production of carbon-based by-products.

In the present invention, the carbon structure is preferably carbon nanotubes and / or graphene. This is because carbon nanotubes and graphene are useful as materials having excellent various properties such as conductivity, thermal conductivity and mechanical properties.

According to the present invention, it is possible to sufficiently suppress the formation of carbon-based by-products when producing a carbon structure by the CVD method.

It is a figure which shows the schematic structure of an example of the manufacturing apparatus of the carbon structure according to this invention. It is a figure which shows the structure of the growth furnace of the manufacturing apparatus shown in FIG. 1 in an enlarged manner. It is a figure which shows the schematic structure of the other example of the manufacturing apparatus of the carbon structure according to this invention.

Hereinafter, embodiments of the present invention will be described in detail.
Here, the method for producing a carbon structure of the present invention is a method for producing a carbon structure by using a chemical vapor deposition (CVD) method. Further, the carbon structure manufacturing apparatus of the present invention is an apparatus for manufacturing a carbon structure by using a CVD method, and is used, for example, when manufacturing a carbon structure by using the carbon structure manufacturing method of the present invention. be able to.

(Manufacturing method of carbon structure)
In the method for producing a carbon structure of the present invention, a raw material gas containing a carbon compound is supplied to a catalyst, and the carbon structure is grown by a chemical vapor phase growth method (A) and the reaction exhaust gas generated in the step (A). The step (B) of supplying a reactive gas containing a compound having 1 or more and 5 or less carbon atoms having a hydroxy group and / or an aldehyde group is included.

In the method for producing a carbon structure of the present invention, a reactive gas containing a compound having a hydroxy group and / or an aldehyde group and having 1 or more and 5 or less carbon atoms is supplied in the step (B). The formation of carbon-based by-products such as group hydrocarbons can be sufficiently suppressed. Therefore, it is possible to sufficiently suppress the adhesion of carbon-based by-products to the formed carbon structure or the inside of the manufacturing apparatus, and prevent deterioration of product quality and blockage of the exhaust pipe.
Although the reason why the formation of carbon-based by-products is suppressed is not clear, the compound itself having a hydroxy group and / or an aldehyde group and having 1 or more and 5 or less carbon atoms, or the compound is formed by decomposition. It is presumed that this is because the compound reacts with the components in the reaction exhaust gas that can generate carbon-based by-products and suppresses the formation of carbon-based by-products.

<Process (A)>
In the step (A), the carbon structure is grown by the CVD method using the raw material gas and the catalyst.
In the method for producing a carbon structure of the present invention, the ambient environment of the catalyst (for example, the range where the distance from the catalyst is 5 cm or less) is arbitrarily set as the reducing gas environment, and the catalyst and / or the reducing gas is heated. The formation step may be carried out before the step (A). By carrying out the formation step, at least one of the effects of reducing the catalyst, promoting the atomization of the catalyst (state suitable for the growth of the carbon structure), and improving the activity of the catalyst can be obtained. Further, in the method for producing a carbon structure of the present invention, a cooling step of cooling the grown carbon structure and the catalyst under an inert gas may be optionally performed after the step (A). By carrying out the cooling step, it is possible to prevent the carbon structure and the catalyst from being oxidized. The formation step and the cooling step can be performed according to, for example, the description in International Publication No. 2014/208097 and JP-A-2011-219316.

[Carbon structure]
Here, examples of the carbon structure manufactured by the manufacturing method of the present invention include any carbon structure that can be manufactured by the CVD method. Among them, as the carbon structure, carbon nanostructures are preferable, carbon nanotubes and / or graphene are more preferable, and carbon nanotubes are further preferable. This is because carbon nanostructures, especially carbon nanotubes and graphene, are useful as materials having excellent various properties such as conductivity, thermal conductivity and mechanical properties.

[Raw material gas]
As the raw material gas used for producing the carbon structure, for example, a gas having a proven material in the production of the carbon structure, such as a gas having a raw material carbon source at the growth temperature, can be appropriately used. Among them, as the raw material gas, it is preferable to use a gas containing a carbon compound such as methane, ethane, ethylene, propane, butane, pentane, hexane, heptane, propylene, acetylene, or a mixture thereof. The raw material gas may contain an inert gas such as helium gas, argon gas, or nitrogen gas in addition to the carbon compound. Further, the carbon compound in the raw material gas may contain an oxygen-containing carbon compound such as acetone or carbon monoxide, but the carbon compound preferably does not contain the oxygen-containing carbon compound.

[catalyst]
As the catalyst, a catalyst having a proven track record in the production of carbon structures can be appropriately used. Specifically, the catalyst is not particularly limited, and for example, iron, nickel, cobalt, molybdenum, and chlorides and alloys thereof, or these are further aluminum, alumina, titania, titanium nitride, and the like. Examples thereof include those compounded with silicon oxide or the like or layered. Specifically, examples of the catalyst include iron-molybdenum thin film, alumina-iron thin film, alumina-cobalt thin film, alumina-iron-molybdenum thin film, aluminum-iron thin film, and aluminum-iron-molybdenum thin film. can.

The catalyst may be supported on any substrate. Here, the member constituting the base material may be any as long as it can support a catalyst for a carbon structure growth reaction on its surface, and it is preferable that the shape can be maintained even at a high temperature of 400 ° C. or higher. The materials include, for example, iron, nickel, chromium, molybdenum, tungsten, titanium, aluminum, manganese, cobalt, copper, silver, gold, platinum, niobium, tantalum, lead, zinc, gallium, indium, germanium and antimony. Examples thereof include metals and alloys and oxides containing these metals; non-metals such as silicon, quartz, glass, mica, graphite and diamond; and ceramics. Metals are preferred because they are cheaper than non-metals and ceramics, especially Fe-Cr (iron-chromium) alloys, Fe-Ni (iron-nickel) alloys, Fe-Cr-Ni (iron-chromium-). Nickel) alloys and the like are suitable.

The shape of the base material includes a flat plate, a thin film, a block, a particle, or a powder. In particular, the flat plate, the particle, or the powder, which can take a large surface area for the volume, has a large amount of carbon structure. It is advantageous in the case of manufacturing.
The particulate substrate includes particles containing a support containing one or more of the elements Al, Si, Zr, O, N, and C, preferably one or more of these. Examples include ceramic particles containing elements. Specific examples thereof include alumina beads which are particulate alumina, silica beads which are particulate silica, zirconia beads which are particulate zirconia, and beads of various composite oxides. The volume average particle diameter of the particulate substrate is preferably 0.1 mm or more, more preferably 0.15 mm or more, and even more preferably 2.0 mm or less.

A carburizing prevention layer may be formed on at least one of the front surface and the back surface of the flat plate-shaped substrate used as the base material. It is desirable that carburizing prevention layers are formed on both the front and back surfaces. This carburizing prevention layer is a protective layer for preventing the substrate from being carburized and deformed during the step (A).

Here, the carburizing prevention layer is preferably made of a metal or ceramic material, and particularly preferably made of a ceramic material having a high carburizing prevention effect. Examples of the metal include copper and aluminum. Examples of the ceramic material include oxides such as aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, titanium oxide, silica alumina, chromium oxide, boron oxide, calcium oxide and zinc oxide, and nitrides such as aluminum nitride and silicon nitride. Of these, aluminum oxide and silicon oxide are preferable because they have a high effect of preventing carbon dioxide.

Either a wet process or a dry process may be applied to support the catalyst on the surface of the substrate. Specifically, without particular limitation, for example, a sputtering vapor deposition method, a method of applying or firing a liquid obtained by dispersing or dissolving metal fine particles or a metal compound in an appropriate solvent, or the like can be applied.

[Chemical vapor deposition]
In the chemical gas phase growth of the carbon structure in the step (A), for example, in a growth furnace, a raw material gas and an optional catalyst activator are supplied to a catalyst arbitrarily supported on a substrate, and the catalyst is used. And by heating at least one of the source gases. Then, in the step (A), the carbon structure is arbitrarily grown on the catalyst supported on the substrate. Although it is not necessary to use the catalyst activator in the step (A), the production efficiency and purity of the carbon structure can be further improved by allowing the catalyst activator to be present in the atmosphere in which the growth reaction of the carbon structure is carried out. It can be further improved. Further, the carbon structure grown in the step (A) can be recovered by using a known means after optionally performing a cooling step.

When heating at least one of the catalyst and the raw material gas, it is more preferable to heat both of them. The reaction temperature for growing the carbon structure is appropriately determined in consideration of the types and concentrations of the catalyst and the raw material gas, the reaction pressure, etc., but the catalyst activation for eliminating the by-products that cause the catalyst deactivation. It is desirable to set the temperature range so that the effect of the substance is fully exhibited. That is, the most desirable temperature range is the temperature at which the catalyst activator can remove by-products such as amorphous carbon and graphite as the lower limit, and the temperature at which the carbon structure as the main product is not oxidized by the catalyst activator. It is to be the upper limit. Therefore, the temperature for heating at least one of the catalyst and the raw material gas may be a temperature at which the carbon structure can grow, but is preferably 400 ° C. or higher and 1100 ° C. or lower, and more preferably 600 ° C. or higher and 900 ° C. It is as follows. Within the above temperature range, the effect of the catalyst activator can be satisfactorily exhibited, and the reaction of the catalyst activator with the carbon structure can be suppressed.

The pressure for growing the carbon structure is preferably 10 ² Pa or more and 10 ⁷ Pa (100 atm) or less, and more preferably 10 ⁴ Pa or more and 3 × 10 ⁵ Pa (3 atm) or less.

As the catalyst activating substance that can be arbitrarily used in the step (A), a substance containing oxygen is more preferable, and a substance that does not cause a great deal of damage to the carbon structure at the growth temperature of the carbon structure is further preferable. For example, water, oxygen, ozone, acidic gas, nitrogen oxide; low carbon oxygen-containing compounds such as carbon monoxide and carbon dioxide; alcohols such as ethanol and methanol; ethers such as tetrahydrofuran; ketones such as acetone; Aldehydes; esters; as well as mixtures thereof are effective. Among these, as the catalyst activator, water, oxygen, carbon dioxide, carbon monoxide, and ethers are preferable, and water and carbon dioxide are particularly preferable.
When alcohols having a hydroxy group and aldehydes having an aldehyde group are used as catalyst activators in the step (A), their concentrations are 1 / of the concentration when they are used as a reactive gas in the step (B). It is preferably 1000 or more and 1/10 or less. Excessive addition of alcohols and aldehydes in the step (A) causes excessive suppression of the CNT synthesis reaction and deactivation (oxidation, etc.) of the catalyst fine particles.
Further, a compound containing carbon and oxygen, such as alcohols and carbon monoxide, can act as a raw material gas and a catalyst activator. For example, when these compounds are used in combination with a raw material gas such as ethylene, which easily decomposes into a carbon source, the compounds containing carbon and oxygen act as catalyst activators. Further, when a compound containing carbon and oxygen is used in combination with a catalyst-activating substance having high activity such as water, it is presumed that the compound containing carbon and oxygen acts as a raw material gas. Further, carbon monoxide and the like can be used as a catalyst activator in which carbon atoms generated by decomposition serve as a carbon source for the growth reaction of a carbon structure, while oxygen atoms oxidize and gasify amorphous carbon and graphite. It is presumed to work.

There is no particular limitation on the amount of the catalyst activator added, but when the catalyst activator is water, the volume concentration in the ambient environment of the catalyst is preferably 10 ppm or more and 10000 ppm or less, more preferably 50 ppm or more and 1000 ppm or less, and further. It is preferably in the range of 100 ppm or more and 700 ppm or less. When the catalyst activator is carbon dioxide, the concentration of carbon dioxide in the ambient environment of the catalyst is preferably 0.2 to 70% by volume, more preferably 0.3 to 50% by volume, and even more preferably 0. It is preferable to use 7 to 20% by volume.

At present, the mechanism by which the catalyst activator exerts its intended function is presumed as follows. In the growth process of the carbon structure, if amorphous carbon, graphite, etc. generated as a by-product adhere to the catalyst, the catalyst is inactivated and the growth of the carbon structure is inhibited. However, in the presence of the catalyst activator, amorphous carbon, graphite, etc. are oxidized to carbon monoxide, carbon dioxide, etc. and gasified, so that the catalyst is purified, the activity of the catalyst is enhanced, and the active life is extended. (Catalyst activation action) is considered to occur.

The chemical vapor deposition of the carbon structure in the step (A) is preferably carried out in a high carbon concentration environment. The high carbon concentration environment refers to a growth atmosphere in which the volume ratio of the raw material gas in the surrounding environment of the catalyst is about 2 to 20%. In particular, since the catalytic activity is remarkably improved in the presence of the catalyst activator, the catalyst does not lose its activity even in a high carbon concentration environment, and the carbon structure can be grown for a long time and the carbon structure can be grown. Growth rate is significantly improved. Here, in a high carbon concentration environment, carbon-based by-products are more likely to be produced than in a low carbon concentration environment. However, according to the production method according to the present invention, the formation of carbon-based by-products can be sufficiently suppressed, so that a high-quality carbon structure can be efficiently produced.

<Process (B)>
In the step (B), a reactive gas containing a compound having a hydroxy group and / or an aldehyde group and having 1 or more and 5 or less carbon atoms is supplied to the reaction exhaust gas generated in the step (A). Then, in the step (B), the supply of the reactive gas produces carbon-based by-products (for example, polycyclic aromatic hydrocarbons such as naphthalene, biphenylene, fluorene, phenanthrene, anthracene, and pyrene) from the reaction exhaust gas. Is sufficiently suppressed.

[Reactive exhaust gas]
The reaction exhaust gas generated in the step (A) usually contains a gas after being used for the growth of the carbon structure in contact with the catalyst, and is not optionally used for the growth of the carbon structure (that is, the catalyst). Unreacted gas (not in contact with) may also be included.
The reaction exhaust gas has a temperature substantially equal to the temperature at which the carbon structure is grown in the step (A), and also contains a component capable of producing a carbon-based by-product.

[Reactive gas]
The reactive gas contains a compound having a hydroxy group and / or an aldehyde group and having 1 or more and 5 or less carbon atoms, and optionally further contains an inert gas such as helium gas, argon gas, or nitrogen gas.

Here, the compound having a hydroxy group (-OH) and having 1 or more and 5 or less carbon atoms is not particularly limited, and has, for example, methanol, ethanol, n-propanol, 2-propanol, n-butanol and the like. Examples include 1 or more and 5 or less alcohols.
The compound having an aldehyde group (-CHO) and having 1 or more and 5 or less carbon atoms is not particularly limited, and examples thereof include aldehydes such as formaldehyde and acetaldehyde, and formic acid.
Further, the compound having 1 or more and 5 or less carbon atoms having a hydroxy group and an aldehyde group is not particularly limited, and examples thereof include 2-hydroxyacetaldehyde.
In addition, these compounds can be used individually by 1 type, or a mixture of 2 or more types.

Among the above-mentioned compounds, the compound having a hydroxy group and / or an aldehyde group and having 1 or more and 5 or less carbon atoms is preferably a compound having a hydroxy group and / or an aldehyde group and having 1 or more and 3 or less carbon atoms, and has a hydroxy group and / or an aldehyde. A compound having a group and having one carbon number is more preferable, at least one selected from the group consisting of methanol, formaldehyde and formic acid is more preferable, and methanol and / or formaldehyde is particularly preferable. This is because these compounds are excellent in the effect of suppressing the formation of carbon-based by-products.

From the viewpoint of effectively suppressing the formation of carbon-based by-products, the concentration of a compound having a hydroxy group and / or an aldehyde group and having 1 or more and 5 or less carbon atoms in a mixed gas of a reactive gas and a reaction exhaust gas. Is preferably 2% by volume or more, more preferably 4% by volume or more, and usually 100% by volume or less, preferably 50% by volume or less.

The reactive gas is usually supplied to the reactive exhaust gas so that the reactive gas does not come into contact with the catalyst. Specifically, the reactive gas can be supplied, for example, on the downstream side of the position where the catalyst and the raw material gas come into contact with each other when viewed in the flow direction of the raw material gas and the reaction exhaust gas. Further, a group on which a catalyst is supported by using a holder such as a holder on which a base material carrying a catalyst is placed and a holder for gripping a part of the base material such as an edge of the base material on which the catalyst is carried. When holding the material, the reactive gas is the back surface side of the base material on which the catalyst is supported (for example, the base material in which at least a part of the edge is held by the holder), or the base material on which the catalyst is supported. It can also be supplied from the back surface side of a holder for holding (for example, a holder on which a base material is placed and held).

From the viewpoint of effectively suppressing the formation of carbon-based by-products, the supply amount of the reactive gas to the reaction exhaust gas is preferably 1/20 or more, and more preferably 1/10 or more. , The amount is preferably equal to or less, and more preferably 1/2 or less.

The reactive exhaust gas and the reactive gas are preferably mixed at a temperature of, for example, 200 ° C. or higher and 900 ° C. or lower. The mixing can be performed by any means such as diffusion, convection or stirring. Further, from the viewpoint of more effectively suppressing the formation of carbon-based by-products, the temperature at which the reactive exhaust gas and the reactive gas are mixed is preferably 400 ° C. or higher, preferably 600 ° C. or higher. Is more preferable, 880 ° C. or lower is preferable, and 860 ° C. or lower is more preferable.

(Carbon structure manufacturing equipment)
The apparatus for producing a carbon structure of the present invention supplies a raw material gas containing a carbon compound to a catalyst to grow the carbon structure by a chemical vapor phase growth method, and a hydroxy group and a hydroxy group in the reactive exhaust gas generated in the growth furnace. / Or a reactive gas supply unit for supplying a reactive gas containing a compound having 1 or more and 5 or less carbon atoms having an aldehyde group. The reactive gas supply unit may be provided inside the growth furnace as long as it can supply the reactive gas to the reaction exhaust gas, or may be provided outside the growth furnace (for example, inside the exhaust pipe). May be good.

Further, in the apparatus for producing a carbon structure of the present invention, a reactive gas supply unit is provided to supply a reactive gas containing a compound having a hydroxy group and / or an aldehyde group and having 1 or more and 5 or less carbon atoms. The formation of carbon-based by-products such as polycyclic aromatic hydrocarbons can be sufficiently suppressed. Therefore, it is possible to sufficiently suppress the adhesion of carbon-based by-products to the formed carbon structure or the inside of the manufacturing apparatus, and prevent deterioration of product quality and blockage of the exhaust pipe.

Hereinafter, an example and other examples of the carbon structure manufacturing apparatus of the present invention will be described in detail with reference to the drawings. As the carbon structure, raw material gas, catalyst and reactive gas, and any catalyst activator, the same method as described above for producing the carbon structure of the present invention can be used. The explanation is omitted.

<Example of carbon structure manufacturing equipment>
FIG. 1 shows an example of an apparatus for manufacturing a carbon structure of the present invention. The manufacturing apparatus 100 shown in FIG. 1 is a continuous manufacturing apparatus that continuously manufactures a carbon structure, and includes an inlet purge unit 1, a formation unit 2, gas mixing preventing means 101 to 103, a growth unit 3, and a cooling unit 4. It includes an outlet purging unit 5, a transport unit 6, and connecting units 7 to 9.

The formation unit 2 includes a formation furnace 2a, the growth unit 3 includes a growth furnace 3a, and the cooling unit 4 includes a cooling furnace 4a. The space inside each of the formation furnace 2a, the growth furnace 3a, and the cooling furnace 4a is in a state of being spatially connected by the connecting portions 7 to 9.

[Inlet purge section]
An inlet purge section 1 is provided at the inlet of the manufacturing apparatus 100. The inlet purge unit 1 is a set of devices for preventing external air from entering the apparatus furnace from the inlet of the base material 20 carrying the catalyst. The inlet purge unit 1 has a function of replacing the surrounding environment of the base material 20 conveyed into the apparatus with purge gas.

The inlet purge unit 1 has a gas curtain structure in which purge gas is jetted from above and below in a shower shape. This prevents external air from entering the manufacturing apparatus 100 from the inlet. The inlet purge unit 1 may be composed of, for example, a furnace or chamber for holding the purge gas, an injection unit for injecting the purge gas, and the like.

The purge gas is preferably an inert gas, and the purge gas is preferably nitrogen, particularly from the viewpoint of safety, cost, and purge property.

[Formation unit]
The formation unit 2 is a set of devices for realizing the formation process. The formation unit 2 has a function of changing the surrounding environment of the catalyst formed on the surface of the base material 20 to a reducing gas environment and heating at least one of the catalyst and the reducing gas.

The formation unit 2 includes a formation furnace 2a for holding the reduction gas, a reduction gas injection unit 2b for injecting the reduction gas into the formation furnace 2a, and a heater 2c for heating at least one of the catalyst and the reduction gas. And an exhaust hood 2d for exhausting the gas in the formation furnace 2a.

A shower head provided with a plurality of injection ports may be used for the reducing gas injection unit 2b. The reduced gas injection unit 2b is provided at a position facing the catalyst-supporting surface of the base material 20. The facing position is a position where the angle formed by the injection axis and the normal line of the base material 20 at each injection port is 0 ° or more and less than 90 °. That is, the direction of the gas flow ejected from the injection port in the reduced gas injection unit 2b is set to be substantially orthogonal to the base material 20.

If such a shower head is used for the reducing gas injection unit 2b, the reducing gas can be uniformly sprayed on the base material 20, and the catalyst can be efficiently reduced. As a result, the uniformity of the carbon structure grown on the base material 20 can be enhanced, and the consumption of the reducing gas can be reduced.

The heater 2c is not limited as long as it can heat at least one of the catalyst and the reducing gas, and examples thereof include a resistance heater, an infrared heater, and an electromagnetic induction heater.

[Growth unit]
The growth unit 3 is a set of devices for realizing a growth step (step (A)) in which a carbon structure is grown by setting the ambient environment of the catalyst as a raw material gas environment and heating at least one of the catalyst and the raw material gas. be. The growth unit 3 includes a growth furnace 3a, which is a furnace that keeps the environment around the base material 20 in the raw material gas environment, a raw material gas injection unit 3b for injecting the raw material gas onto the base material 20, and a catalyst. It includes a heater 3c for heating at least one of the raw material gas and an exhaust hood 3d for exhausting the gas in the growth furnace 3a. Further, as shown in an enlarged view of the growth furnace 3a in FIG. 2, the growth unit 3 further includes reactive gas supply units 16 and 17 for supplying the reactive gas to the reactive exhaust gas generated in the growth furnace 3a. Further, the growth unit 3 may have a catalyst activator injection unit (not shown) for supplying the catalyst activator. The raw material gas injection unit 3b may also serve as a catalyst activator injection unit. Further, only one of the reactive gas supply unit 16 and the reactive gas supply unit 17 may be provided.

The growth furnace 3a is a furnace for performing a growth step, and the ambient environment of the catalyst on the base material 20 is used as a raw material gas environment, and at least one of the catalyst and the raw material gas is heated to be a base material. It is a furnace for obtaining a base material 10 with a carbon structure obtained by growing a carbon structure on 20.

In the growth step, it is preferable to inject the raw material gas from the raw material gas injection unit 3b onto the base material 20 moving in the growth furnace 3a.

At least one of the raw material gas injection unit 3b and the exhaust hood 3d is provided, and the total gas flow rate injected from all the raw material gas injection units 3b and the total gas flow rate exhausted from all the exhaust hoods 3d are set. It is preferably about the same amount or the same amount. By doing so, it is possible to prevent the raw material gas from flowing out of the growth furnace 3a and the gas outside the growth furnace 3a from flowing into the growth furnace 3a.

Examples of the heater 3c include a resistance heater, an infrared heater, an electromagnetic induction heater, and the like.

The reactive gas supply unit 16 and the reactive gas supply unit 17 do not come into contact with the raw material gas before the reactive gas is used for the catalyst and the growth of the carbon structure, and after the reactive gas is used for the growth of the carbon structure. It is arranged in a position where it is well mixed with the reactive exhaust gas of. Specifically, as shown in FIG. 2, the reactive gas supply unit 16 is installed below the base material 10 with a carbon structure formed by growing a carbon structure on the base material 20 in the growth furnace 3a. ing. More specifically, the reactive gas supply unit 16 shown in FIG. 2 is arranged below the mesh belt 6a of the transport unit 6 passing through the growth furnace 3a, extends in the furnace length direction, and is lateral (FIG. In 2, it is composed of a pipe provided with a hole for injecting a reactive gas in the left-right direction). Further, the reactive gas supply unit 17 is installed in the exhaust hood 3d. More specifically, the reactive gas supply unit 17 shown in FIG. 2 includes a pipe that directly injects the reactive gas into the exhaust hood 3d that collects the reactive exhaust gas exhausted from the growth furnace 3a to the exhaust pipe 23. ..
From the viewpoint of more effectively suppressing the generation of carbon-based by-products by the reactive gas supplied from the reactive gas supply units 16 and 17, the exhaust pipe 23 is provided with a heater for heating the inside of the exhaust pipe 23. (Not shown) or a heat insulating material (not shown) for keeping the exhaust pipe 23 warm is preferably provided.

[Cooling unit]
The cooling unit 4 is a set of devices for realizing the cooling process, that is, for cooling the base material 10 with a carbon structure in which the carbon structure has grown. The cooling unit 4 has a function of cooling the carbon structure, the catalyst, and the substrate after the growth step.

The cooling unit 4 has a configuration in which a water cooling method and an air cooling method are combined, and has a cooling furnace 4a for holding the inert gas, a cooling gas injection unit 4b for injecting the inert gas into the space inside the cooling furnace 4a, and a cooling gas injection unit 4b. , It is composed of a water-cooled cooling pipe 4c arranged so as to surround the space inside the cooling furnace 4a. The cooling unit 4 may have a configuration of only a water cooling system or a configuration of only an air cooling system.

By cooling with the cooling unit 4, it is possible to prevent oxidation of the carbon structure, the catalyst, and the substrate after the growth step.

[Exit purge section]
At the outlet of the manufacturing apparatus 100, an outlet purge unit 5 having substantially the same structure as the inlet purge unit 1 is provided. The outlet purge unit 5 is a set of devices for preventing external air from entering the inside from the outlet of the manufacturing device 100. The outlet purge unit 5 has a function of changing the surrounding environment of the base material 10 with a carbon structure into a purge gas environment.

The outlet purge unit 5 sprays the purge gas from above and below in a shower shape to prevent outside air from entering the cooling furnace 4a from the outlet. The outlet purge unit 5 may be composed of a furnace or chamber for maintaining the purge gas environment, an injection unit for injecting the purge gas, and the like.

As the purge gas, an inert gas is preferable, and the purge gas is particularly preferably nitrogen from the viewpoints of safety, cost, purge property and the like.

[Connection part]
The connection portions 7 to 9 are a set of devices for spatially connecting the space inside the furnace of each unit and preventing the base material from being exposed to the outside air when the base material is transported from the unit to the unit. That is. Examples of the connecting portions 7 to 9 include a furnace or a chamber that can block the environment around the base material from the outside air and allow the base material to pass from unit to unit.

The inlet purge unit 1 and the formation unit 2 are spatially connected by a connection unit 7. A gas mixing preventing means 101 is arranged in the connecting portion 7, and a mixed gas of the purge gas injected in the inlet purge portion 1 and the reduced gas injected from the reducing gas injection unit 2b is exhausted. This prevents the purge gas from being mixed into the space inside the formation furnace 2a and the reducing gas from being mixed into the inlet purge portion 1 side.

The formation unit 2 and the growth unit 3 are spatially connected by a connecting portion 8. A gas mixing preventing means 102 is arranged in the connection portion 8, and exhausts the reducing gas in the space inside the formation furnace 2a, the raw material gas in the space inside the growth furnace 3a, and the catalyst activator. This prevents the mixing of the raw material gas or the catalyst activator into the space inside the formation furnace 2a and the mixing of the reducing gas into the space inside the growth furnace 3a.

The growth unit 3 and the cooling unit 4 are spatially connected by a connecting portion 9. A gas mixing preventing means 103 is arranged in the connecting portion 9, and exhausts a mixed gas of a raw material gas and a catalyst activator in the space inside the growth furnace 3a and an inert gas in the space inside the cooling furnace 4a. This prevents the mixing of the raw material gas or the catalyst activator into the space inside the cooling furnace 4a and the mixing of the inert gas into the space inside the growth furnace 3a.

The carbon structure manufacturing apparatus 100 may further include a heating means for heating the connection portion 9 between the growth unit 3 and the cooling unit 4. This is because when the temperature near the outlet of the growth furnace 3a drops, the decomposition product of the raw material gas may become amorphous carbon and deposit on the carbon structure.

As a specific form of the heating means for heating the connecting portion 9, for example, the seal gas ejected by the gas mixing preventing means 103 between the growth unit 3 and the cooling unit 4 may be heated. By heating the seal gas, the outlet of the growth furnace 3a and its vicinity can be heated.

[Measures to prevent gas contamination]
The gas mixing preventing means 101 to 103 are a set of devices for realizing a function of preventing the gas existing in the furnace space of each unit from being mixed with each other. The gas mixing prevention means 101 to 103 are installed in connection portions 7 to 9 that spatially connect the space inside the furnace of each unit to each other. The gas mixing prevention means 101 to 103 include seal gas injection portions 101b to 103b for ejecting seal gas along the opening surfaces of the inlet and outlet of the base material in each furnace, and the seal gas mainly injected (and other nearby areas). Each of the exhaust units 101a to 103a is provided with at least one exhaust unit 101a to 103a that sucks gas) so as not to enter each furnace and exhausts it to the outside of the apparatus.

By injecting the seal gas along the opening surface of the furnace, the seal gas can block the entrance and exit of the furnace, and the gas outside the furnace can be prevented from being mixed into the furnace. Further, by exhausting the seal gas to the outside of the apparatus, it is possible to prevent the seal gas from being mixed into the furnace.

The sealing gas is preferably an inert gas, and particularly preferably nitrogen from the viewpoint of safety, cost and the like. As for the arrangement of one seal gas injection unit 101b to 103b and one exhaust unit 101a to 103a, one exhaust unit may be arranged adjacent to one seal gas injection unit, or the mesh belt of the transport unit 6 may be arranged. The exhaust unit may be arranged so as to face the seal gas injection unit with 6a in between. It is preferable that the seal gas injection portions 101b to 103b and the exhaust portions 101a to 103a are arranged so that the overall configuration of the gas mixing prevention means 101 to 103 has a structure symmetrical in the furnace length direction.

For example, it is preferable to arrange two seal gas injection parts at both ends of one exhaust part so as to have a structure symmetrical with respect to the furnace length direction with the exhaust part as the center. Further, it is preferable that the total gas flow rate injected from the seal gas injection units 101b to 103b and the total gas flow rate exhausted from the exhaust units 101a to 103a are substantially the same amount. This makes it possible to prevent gas from the spaces on both sides of the gas mixing preventing means 101 to 103 from being mixed with each other, and also to prevent the seal gas from flowing out to the spaces on both sides. By installing such gas mixing preventing means 101 to 103 at both ends of the growth furnace 3a, it is possible to prevent the flow of the seal gas and the flow of gas in the growth furnace 3a from interfering with each other. Further, it is possible to prevent the gas flow from being disturbed due to the inflow of the seal gas into the growth furnace 3a. Therefore, it is possible to realize an apparatus suitable for continuous production of carbon structures.

The gas mixing prevention means 101 to 103 are not limited to the configuration in the present embodiment, and for example, the spatial connection of each unit is mechanically cut off at a time other than the time when the base material moves from the unit to the unit. It may be a gate valve device. Further, it may be a gas curtain device that cuts off the spatial connection of each unit by injecting an inert gas.

[Transport unit]
The transport unit 6 is a set of devices necessary for continuously carrying a plurality of base materials 20 into the carbon structure manufacturing apparatus 100. The transport unit 6 includes a mesh belt 6a and a belt drive unit 6b. The base material 20 is configured to be conveyed in each furnace space in the order of the formation unit 2, the growth unit 3, and the cooling unit 4 by the transfer unit 6.

The transfer unit 6 is of a belt conveyor type, and transfers the base material 20 having a catalyst supported on its surface from the space inside the formation furnace 2a to the space inside the cooling furnace 4a via the space inside the growth furnace 3a. The transport unit 6 transports the base material 20 by a mesh belt 6a driven by a belt drive unit 6b using, for example, an electric motor with a speed reducer. Then, in the carbon structure manufacturing apparatus 100, a space is provided between the space inside the formation furnace 2a and the space inside the growth furnace 3a, and between the space inside the growth furnace 3a and the space inside the cooling furnace 4a by connecting portions 8 and 9. Is connected. As a result, the mesh belt 6a on which the base material 20 is placed can pass between the furnaces.

When the carbon structure manufacturing apparatus 100 continuously manufactures a carbon structure and includes a transport unit, the specific configuration thereof is not limited to the above-described configuration, for example. The transfer unit may be a robot arm, a robot arm drive device, or the like in a multi-chamber system.

Then, in the manufacturing apparatus 100, the base material 20 having a catalyst on the surface is continuously conveyed by the transfer unit 6, and the inlet purge unit 1, the formation unit 2, the growth unit 3, the cooling unit 4, and the outlet purge unit 5 are continuously conveyed. Are passed in sequence. During that time, the catalyst is reduced under the reducing gas environment in the formation unit 2, the carbon structure grows on the surface of the base material under the raw material gas environment in the growth unit 3, and is cooled in the cooling unit 4. Further, in the growth furnace 3a, the production of carbon-based by-products is suppressed by the supply of the reactive gas from the reactive gas supply units 16 and 17.

<Other examples of carbon structure manufacturing equipment>
Further, FIG. 3 shows another example of the carbon structure manufacturing apparatus of the present invention. The manufacturing apparatus 200 shown in FIG. 3 is a manufacturing apparatus that performs a formation step and a growth step in one furnace (growth furnace 210).

The manufacturing apparatus 200 shown in FIG. 3 includes a growth furnace 210, a gas introduction port 220, a gas discharge port 230, a heater (heater) 240, and a reactive gas supply pipe 250 as a reactive gas supply unit. Further, in the growth furnace 210, a holder 211 for placing a base material carrying a catalyst and an arbitrary perforated plate 212 for preventing backflow of gas are provided. Further, the reactive gas supply pipe 250 is configured to supply the reactive gas into the growth furnace 210 between the perforated plate 212 and the gas discharge port 230.

Then, in the manufacturing apparatus 200, the formation step is carried out by arbitrarily supplying the reducing gas from the gas introduction port 220 in a state where the base material supporting the catalyst is installed on the holder 211. Further, the raw material gas and an arbitrary catalyst activator are supplied from the gas introduction port 220, and the reactive gas is supplied from the reactive gas supply pipe 250 to carry out the growth step. This makes it possible to obtain a carbon structure while suppressing the formation of carbon-based by-products.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Preparation of the base material on which the catalyst is supported)
As a base material, a flat plate of Fe—Cr alloy (manufactured by JFE Steel Corporation, SUS430, Cr: 18% by mass) having a length of 500 mm, a width of 500 mm, and a thickness of 0.6 mm was prepared. When the surface roughness of a plurality of places was measured using a laser microscope, the arithmetic average roughness Ra was 0.063 μm.
Further, 1.9 g of aluminum tri-sec-butoxide was dissolved in 100 ml (78 g) of 2-propanol, and 0.9 g of triisopropanolamine was further added and dissolved as a stabilizer to prepare a coating agent for forming an alumina film.
Then, in an environment of room temperature of 25 ° C. and relative humidity of 50%, the above-mentioned coating agent for forming an alumina film was applied onto the substrate by dip coating. Specifically, after immersing the substrate in the coating agent for forming an alumina film, the substrate was held for 20 seconds, the substrate was pulled up at a pulling speed of 10 mm / sec, and then air-dried for 5 minutes. Next, after heating for 30 minutes in an air environment of 300 ° C., the mixture was cooled to room temperature. As a result, an alumina film having a film thickness of 40 nm was formed on the substrate.
Subsequently, 174 mg of iron acetate was dissolved in 100 ml of 2-propanol, and 190 mg of triisopropanolamine was further added and dissolved as a stabilizer to prepare an iron film coating agent.
Then, in an environment of room temperature of 25 ° C. and relative humidity of 50%, the iron film coating agent was applied onto the substrate on which the above-mentioned alumina film was formed by dip coating. Specifically, after immersing the base material in the iron film coating agent, the base material was held for 20 seconds and the base material was pulled up at a pulling speed of 3 mm / sec. Then, it was air-dried for 5 minutes. Next, after heating for 30 minutes in an air environment of 100 ° C., the mixture was cooled to room temperature. As a result, a base material having a catalyst film with a film thickness of 3 nm (a base material on which a catalyst was supported) was produced.

(Example 1)
A base material on which a catalyst is supported is cut out to a size of 40 mm in length × 40 mm in width, and is installed in the manufacturing apparatus 200 shown in FIG. 3, and a formation step and a growth step are sequentially performed to obtain carbon nanotubes (CNTs). Manufactured.
Specifically, after the base material was placed on the holder 211, the formation step was carried out for 23 minutes under the conditions of a temperature of 750 ° C. and a flow rate of hydrogen gas as a reducing gas of 3000 sccm, and further, in Table 1 at a temperature of 800 ° C. The raw material gas (carbon compound: ethylene, catalyst activator: water) and the reactive gas having the composition shown were supplied at the flow rate shown in Table 1 for 10 minutes, and the operation of growing CNT on the substrate was repeated 30 times.
As the reaction furnace 210, a quartz furnace was used. In addition, a metal by-product collection tube was installed in the region S (immediately upstream of the gas discharge port 230) shown by the alternate long and short dash line in FIG. 3 in the reactor 210. Further, although not shown, in order to control the gas flow rate, a control device including a flow rate control valve and a pressure control valve is attached at an appropriate place.
Then, by measuring the weight of the by-product adhering to the inside of the by-product collecting tube, the by-product adhering rate per unit area of the by-product collecting tube was calculated. The results are shown in Table 1.

(Comparative Example 1)
The operation of growing CNTs on the substrate was repeated 30 times in the same manner as in Example 1 except that only the raw material gas was supplied without using the reactive gas, and the by-product adhesion rate was adjusted in the same manner as in Example 1. I asked. The results are shown in Table 1.

(Comparative Examples 2 to 3)
The operation of growing CNTs on the substrate was repeated 30 times in the same manner as in Example 1 except that the composition and flow rate of the reactive gas were changed as shown in Table 1, and by-products adhered in the same manner as in Example 1. I asked for speed. The results are shown in Table 1.

From Table 1, in Example 1 in which methanol (gas) was used, Comparative Example 1 in which no reactive gas was used, a gas to which hydrogen was added so as to be 20% by volume with respect to the total amount was used as the reactive gas. Compared with Comparative Example 2 and Comparative Example 3 in which air was added so that the amount of oxygen was 5% by volume with respect to the total amount as the reactive gas, the by-product adhesion rate was 1/12 or less. It can be seen that it has been reduced.
The average values of the characteristics of the CNTs repeatedly produced in Example 1 and Comparative Examples 1 to 3 were: yield: 2.0 mg / cm ² , G / D ratio: 6.3, and specific surface area: 1100 m ² . It was / g. From this, it was confirmed that CNTs having the same characteristics could be manufactured.

(Experimental example)
The raw material gas and the reactive gas were flowed into the manufacturing apparatus 200 in which the base material was not installed under the same conditions as when the CNTs were grown on the base material in Example 1 and Comparative Examples 1 to 3. Then, the gas component near the by-product collection tube was sampled, and the composition was measured using a gas chromatograph mass spectrometer (GCMS). The results are shown in Table 2.

Table 2 shows that formaldehyde (CH _2O ) is produced by the thermal decomposition of methanol, and it is possible that compounds having hydroxy and / or aldehyde groups contribute to the suppression of PAHs. Was done.

According to the present invention, it is possible to sufficiently suppress the formation of carbon-based by-products when producing a carbon structure by the CVD method.

1 Inlet purge unit 2 Formation unit 2a Formation furnace 2b Reduction gas injection unit 2c Heater 2d Exhaust hood 3 Growth unit 3a Growth furnace 3b Raw material gas injection unit 3c Heater 3d Exhaust hood 4 Cooling unit 4a Cooling furnace 4b Cooling gas injection unit 4c Water cooling Pipe 5 Outlet purge part 6 Conveyance unit 6a Mesh belt 6b Belt drive part 7-9 Connection part 10, 20 Base material 16, 17 Reactive gas supply part 23 Exhaust pipe 101 to 103 Gas mixing prevention means 101a to 103a Exhaust part 101b to 103b Seal gas injection unit 100, 200 Manufacturing equipment 210 Growth furnace 211 Cage 212 Perforated plate 220 Gas inlet 230 Gas discharge port 240 Heater 250 Reactive gas supply pipe

Claims (6)

A step (A) of supplying a raw material gas containing a carbon compound to a catalyst and growing a carbon structure by a chemical vapor deposition method.
The step (B) of supplying the reactive gas containing the compound having a hydroxy group and / or a carbon number 1 having a hydroxy group and / or an aldehyde group to the reaction exhaust gas generated in the step (A).
A method for manufacturing a carbon structure, including. The method for producing a carbon structure according to claim 1 , wherein the compound is at least one selected from the group consisting of methanol, formaldehyde and formic acid. The method for producing a carbon structure according to claim 1 or 2, wherein the carbon structure is a carbon nanotube and / or graphene. A growth furnace that supplies a raw material gas containing a carbon compound to a catalyst and grows a carbon structure by a chemical vapor deposition method.
A reactive gas supply unit that supplies a reactive gas containing a compound having 1 carbon atom having a hydroxy group and / or an aldehyde group to the reactive exhaust gas generated in the growth furnace.
A carbon structure manufacturing device. The apparatus for producing a carbon structure according to claim 4 , wherein the compound is at least one selected from the group consisting of methanol, formaldehyde and formic acid. The apparatus for producing a carbon structure according to claim 4 or 5, wherein the carbon structure is a carbon nanotube and / or graphene.

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