JP2019167266A - Manufacturing method and manufacturing apparatus of carbon structure - Google Patents

Abstract

To provide a manufacturing method of a carbon structure capable of suppressing sufficiently generation of a carbon-based by-product, when manufacturing a carbon structure by a chemical vapor deposition (CVD) method.SOLUTION: A manufacturing method of a carbon structure includes a step (A) for supplying raw material gas containing a carbon compound to a catalyst, and growing a carbon structure by a chemical vapor deposition method, and a step (B) for supplying reactive gas containing a compound having a carbon number of 1 or more and 5 or less having a hydroxy group and/or an aldehyde group, to reaction exhaust gas generated in the step (A).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a carbon structure manufacturing method and a carbon structure manufacturing apparatus, and in particular, a method of manufacturing a carbon structure using a chemical vapor deposition method and a carbon structure using a chemical vapor deposition method. The present invention relates to an apparatus to be manufactured.

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

  Here, in the production of a carbon structure using the CVD method, when a carbon structure is formed by bringing a raw material gas containing carbon into contact with a catalyst, a volatile organic compound (VOC) or polycyclic aromatic is formed by a side reaction. Carbon-based by-products such as group hydrocarbons (PAHs) are produced. And the produced | generated carbon-type by-product may adhere to a carbon structure and cause the fall of product quality, or may obstruct | occlude the exhaust pipe of a manufacturing apparatus, and may reduce manufacturing efficiency.

  Therefore, in Patent Document 1, for example, when a raw material gas is supplied onto a substrate carrying a catalyst on the surface to produce CNT, the raw material gas used for the growth of CNT, hydrogen, ammonia, oxygen, By mixing and reacting with a reaction gas such as ozone or water vapor, carbon solids are prevented from being produced as carbon-based byproducts.

JP2011-219316A

  However, the above conventional technique has room for improvement in terms of further suppressing the generation of carbon-based byproducts when the carbon structure is manufactured by the CVD method.

  Then, an object of this invention is to provide the manufacturing method and manufacturing apparatus of a carbon structure which can fully suppress the production | generation of a carbon-type by-product when manufacturing a carbon structure by CVD method.

  The present inventor has intensively studied for the purpose of solving the above problems. And if this inventor uses the reactive gas containing a C1-C5 compound which has a hydroxyl group and / or an aldehyde group, it will produce | generate a carbon-type by-product in manufacture of the carbon structure by CVD method. Has been found to be sufficiently suppressed, and the present invention has been completed.

  That is, the present invention aims to advantageously solve the above-mentioned problems, and a method for producing a carbon structure according to the present invention supplies a raw material gas containing a carbon compound to a catalyst, and a chemical vapor deposition method. A step (A) of growing a carbon structure by the step, and a step of supplying a reactive gas containing a compound having 1 to 5 carbon atoms having a hydroxy group and / or an aldehyde group to the reaction exhaust gas generated in the step (A) (B). Thus, if a reactive gas containing a compound having 1 to 5 carbon atoms having a hydroxy group and / or an aldehyde group is supplied to the reaction exhaust gas generated in the step (A), the production of a carbon-based byproduct is generated. Can be sufficiently suppressed.

  Another object of the present invention is to advantageously solve the above-described problems. The carbon structure manufacturing apparatus of the present invention supplies a raw material gas containing a carbon compound to a catalyst, and a chemical vapor deposition method is provided. And a reactive gas supply unit for supplying a reactive gas containing a compound having a hydroxy group and / or an aldehyde group and having a carbon number of 1 to 5 to a reaction exhaust gas generated in the growth furnace It is characterized by providing. Thus, if a reactive gas supply unit is provided and a reactive gas containing a compound having 1 to 5 carbon atoms having a hydroxy group and / or an aldehyde group is supplied to a reaction exhaust gas generated in a growth furnace, Generation of by-products can be sufficiently suppressed.

  In the present invention, the compound is preferably a C 1 compound having a hydroxy group and / or an aldehyde group. This is because if a compound having 1 carbon is used, the production of carbon-based byproducts can be further suppressed.

  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 by-products.

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

  ADVANTAGE OF THE INVENTION According to this invention, when manufacturing a carbon structure by CVD method, the production | generation of a carbon-type by-product can fully be suppressed.

It is a figure which shows schematic structure of an example of the manufacturing apparatus of the carbon structure according to this invention. It is a figure which expands and shows the structure of the growth furnace of the manufacturing apparatus shown in FIG. It is a figure which shows 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 using a chemical vapor deposition (CVD) method. The carbon structure production apparatus of the present invention is an apparatus for producing a carbon structure using a CVD method, and is used, for example, when producing a carbon structure using the carbon structure production method of the present invention. be able to.

(Method for producing 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 chemical vapor deposition, and the reaction exhaust gas generated in the step (A) is used. And (B) supplying a reactive gas containing a compound having 1 to 5 carbon atoms and having a hydroxy group and / or an aldehyde group.

And in the manufacturing method of the carbon structure of this invention, since the reactive gas containing the C1-C5 compound which has a hydroxyl group and / or an aldehyde group in process (B) is supplied, polycyclic aromatic The generation of carbon-based byproducts such as group hydrocarbons can be sufficiently suppressed. Accordingly, it is possible to sufficiently suppress the carbon-based by-product from adhering to the formed carbon structure and the manufacturing apparatus, and to prevent the product quality from being lowered and the exhaust pipe from being blocked.
The reason why the production of carbon-based byproducts is suppressed is not clear, but it is formed by the compound itself having a hydroxy group and / or an aldehyde group having 1 to 5 carbon atoms, or the compound is decomposed. It is inferred that this is because the compound reacts with components in the reaction exhaust gas that can generate a carbon-based by-product, and suppresses the generation of the carbon-based by-product.

<Process (A)>
In the step (A), a carbon structure is grown by a CVD method using a source gas and a catalyst.
In the carbon structure production method of the present invention, the environment surrounding the catalyst (for example, the distance from the catalyst is in a range of 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 performed before step (A). By performing the formation step, at least one of the following effects can be obtained: reduction of the catalyst, promotion of the fine particle formation of the catalyst (conditioning suitable for the growth of the carbon structure), and improvement of the catalyst activity. Moreover, in the manufacturing method of the carbon structure of this invention, you may optionally implement the cooling process which cools the grown carbon structure and a catalyst under inert gas after a process (A). By performing the cooling step, the carbon structure and the catalyst can be prevented from being oxidized. And a formation process and a cooling process can be performed according to description of international publication 2014/208097, Unexamined-Japanese-Patent No. 2011-219316, etc., for example.

[Carbon structure]
Here, as a carbon structure manufactured with the manufacturing method of this invention, the arbitrary carbon structures which can be manufactured by CVD method are mentioned. Especially, as a carbon structure, a carbon nanostructure is preferable, a carbon nanotube and / or graphene are more preferable, and a carbon nanotube is still more preferable. This is because carbon nanostructures, particularly carbon nanotubes and graphene, are useful as materials excellent in various properties such as conductivity, thermal conductivity, and mechanical properties.

[Raw material gas]
As the source gas used for generating the carbon structure, for example, a gas having a proven record in the manufacture of the carbon structure such as a gas having a source carbon source at the growth temperature can be appropriately used. Among these, as the source 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 source gas may contain an inert gas such as helium gas, argon gas, or nitrogen gas in addition to the carbon compound. 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 an oxygen-containing carbon compound.

[catalyst]
As the catalyst, those having a proven record in the production of carbon structures can be used as appropriate. Specifically, the catalyst is not particularly limited. For example, iron, nickel, cobalt, molybdenum, and chlorides and alloys thereof, or these may be aluminum, alumina, titania, titanium nitride, A compounded or layered material such as silicon oxide can be given. Specifically, examples of the catalyst include an iron-molybdenum thin film, an alumina-iron thin film, an alumina-cobalt thin film, an alumina-iron-molybdenum thin film, an aluminum-iron thin film, and an aluminum-iron-molybdenum thin film. it can.

  The catalyst may be supported on an arbitrary base material. Here, the member which comprises a base material should just be the thing which can carry | support the catalyst for carbon structure growth reaction on the surface, and it is preferable that a shape can be maintained also at the high temperature of 400 degreeC or more. Examples of the material include iron, nickel, chromium, molybdenum, tungsten, titanium, aluminum, manganese, cobalt, copper, silver, gold, platinum, niobium, tantalum, lead, zinc, gallium, indium, germanium, and antimony. Examples include metals and alloys and oxides containing these metals; nonmetals such as silicon, quartz, glass, mica, graphite and diamond; and ceramics. Metals are preferable because they are low in cost compared to non-metals and ceramics, and in particular, Fe—Cr (iron-chromium) alloys, Fe—Ni (iron-nickel) alloys, Fe—Cr—Ni (iron-chromium—). Nickel) alloys and the like are preferred.

Examples of the shape of the substrate include a flat plate shape, a thin film shape, a block shape, a particle shape, and a powder shape. In particular, a flat plate shape, a particle shape, or a powder shape that can take a large surface area for its volume is a large amount of carbon structures. This is advantageous when manufacturing.
In addition, as the particulate base material, particles including a support containing any one or more elements of Al, Si, Zr, O, N, and C, preferably any one or more of these. Examples include ceramic particles containing elements. Specific examples include alumina beads that are particulate alumina, silica beads that are particulate silica, zirconia beads that 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 more preferably 2.0 mm or less.

  In addition, the carburization prevention layer may be formed in at least any one of the surface of the flat substrate used as a base material, and a back surface. It is desirable that carburization 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 carburization prevention layer is preferably made of a metal or a ceramic material, and particularly preferably made of a ceramic material having a high carburization prevention effect. Examples of the metal include copper and aluminum. Examples of the ceramic material include aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, titanium oxide, silica alumina, chromium oxide, boron oxide, calcium oxide, zinc oxide and other oxides, and nitrides such as aluminum nitride and silicon nitride. Among them, aluminum oxide and silicon oxide are preferable because they have a high effect of preventing carburization.

  Either a wet process or a dry process may be applied to support the catalyst on the substrate surface. Specifically, without limitation, for example, a sputtering vapor deposition method, a method of applying and baking a liquid in which metal fine particles or a metal compound are dispersed or dissolved in an appropriate solvent, and the like can be applied.

[Chemical vapor deposition]
In the chemical vapor deposition of the carbon structure in the step (A), for example, a raw material gas and an optional catalyst activation material are supplied to a catalyst arbitrarily supported on a substrate in a growth furnace, and the catalyst And heating at least one of the source gases. And in a process (A), a carbon structure is grown on the catalyst arbitrarily carry | supported by the base material. In the step (A), it is not necessary to use a catalyst activator, but the presence of the catalyst activator in the atmosphere in which the growth reaction of the carbon structure is performed further increases the production efficiency and purity of the carbon structure. It can be further improved. In addition, the carbon structure grown in the step (A) can be recovered using a known means after arbitrarily performing a cooling step.

  In addition, 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 type and concentration of the catalyst and the raw material gas, the reaction pressure, etc., but the catalyst activation for eliminating the by-product causing the catalyst deactivation. It is desirable to set the temperature range in which the effect of the substance is sufficiently developed. In other words, the most desirable temperature range is a temperature at which the catalyst activator can remove by-products such as amorphous carbon and graphite, and a temperature at which the carbon structure as the main product is not oxidized by the catalyst activator. The upper limit is set. Therefore, the temperature for heating at least one of the catalyst and the raw material gas may be any temperature at which the carbon structure can be grown, but is preferably 400 ° C. or higher and 1100 ° C. or lower, more preferably 600 ° C. or higher and 900 ° C. or lower. It is as follows. If it is the said temperature range, the effect of a catalyst activation material can be expressed favorably, and it can suppress that a catalyst activation material reacts with a carbon structure.

Further, the pressure at which the carbon structure is grown is preferably 10 ² Pa or more and 10 ⁷ Pa (100 atmospheric pressure) or less, more preferably 10 ⁴ Pa or more and 3 × 10 ⁵ Pa (3 atmospheric pressure) or less.

As the catalyst activator that can be optionally used in the step (A), a substance containing oxygen is more preferable, and a substance that does not cause much damage to the carbon structure at the growth temperature of the carbon structure is more preferable. For example, water, oxygen, ozone, acid gas, nitric oxide; oxygen-containing compounds having a low carbon number 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 useful. Among these, water, oxygen, carbon dioxide, carbon monoxide, and ethers are preferable as the catalyst activator, and water and carbon dioxide are particularly preferable.
In addition, when alcohols having a hydroxy group and aldehydes having an aldehyde group are used as the catalyst activator in the step (A), the concentration thereof is 1 / of the concentration when used as the reactive gas in the step (B). It is preferable to set it to 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, for example, a compound containing carbon and oxygen such as alcohols or carbon monoxide can act as a raw material gas or a catalyst activator. For example, when these compounds are used in combination with a raw material gas such as ethylene, which is likely to decompose and become a carbon source, these compounds containing carbon and oxygen act as catalyst activators. In addition, when a compound containing carbon and oxygen is used in combination with a catalyst activation material having high activity such as water, it is presumed that the compound containing carbon and oxygen acts as a raw material gas. Furthermore, carbon monoxide, etc., can be used as a catalyst activator, in which carbon atoms generated by decomposition become a carbon source for the growth reaction of the carbon structure, while oxygen atoms oxidize amorphous carbon and graphite to gasify them. Presumed to work.

  Although there is no particular limitation on the amount of the catalyst activator added, when the catalyst activator is water, the volume concentration in the ambient environment of the catalyst is preferably 10 ppm or more and 10,000 ppm or less, more preferably 50 ppm or more and 1000 ppm or less, Preferably it is good to set it as the range of 100 ppm or more and 700 ppm or less. When the catalyst activation material 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 still more preferably 0.00. It is good to set it as 7-20 volume%.

  Note that the mechanism by which the catalyst activator exhibits the desired function is presumed as follows at present. During the growth process of the carbon structure, if amorphous carbon, graphite, or the like generated as a secondary material adheres to the catalyst, the catalyst is deactivated and the growth of the carbon structure is inhibited. However, in the presence of a catalyst activator, amorphous carbon and graphite are oxidized to carbon monoxide and carbon dioxide and gasified, so that the catalyst is cleaned, increasing the activity of the catalyst and extending the active life. It is considered that (catalyst activation action) is developed.

  And it is preferable to perform the chemical vapor deposition of the carbon structure in the step (A) in a high carbon concentration environment. The high carbon concentration environment means a growth atmosphere in which the volume ratio of the source gas in the environment surrounding the catalyst is about 2 to 20%. In particular, in the presence of a catalyst activator, the catalytic activity is remarkably improved. Therefore, even in a high carbon concentration environment, the catalyst does not lose its activity, and the carbon structure can be grown for a long time. The growth rate is significantly improved. Here, in a high carbon concentration environment, a carbon-based by-product is easily generated compared to a low carbon concentration environment. However, since the production method according to the present invention can sufficiently suppress the production of carbon-based byproducts, a high-quality carbon structure can be produced efficiently.

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

[Reaction exhaust gas]
The reaction exhaust gas generated in the step (A) usually contains a gas after contact with the catalyst and used for the growth of the carbon structure, and is not arbitrarily used for the growth of the carbon structure (ie, the catalyst). Unreacted gas (not in contact with) may also be included.
The reaction exhaust gas has a temperature substantially equal to the temperature when the carbon structure is grown in the step (A), and includes a component that can generate a carbon-based byproduct.

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

Here, the compound having 1 to 5 carbon atoms having a hydroxy group (—OH) is not particularly limited, and examples thereof include methanol, ethanol, n-propanol, 2-propanol, n-butanol and the like. Examples of the alcohol include 1 or more and 5 or less.
In addition, the compound having 1 to 5 carbon atoms and having an aldehyde group (—CHO) is not particularly limited, and examples thereof include aldehydes such as formaldehyde and acetaldehyde, and formic acid.
Furthermore, the compound having 1 to 5 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 in mixture of 2 or more types.

  Among the compounds described above, the compound having 1 to 5 carbon atoms having a hydroxy group and / or an aldehyde group is preferably a compound having 1 to 3 carbon atoms having a hydroxy group and / or an aldehyde group. The compound having 1 group having 1 group 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 byproducts.

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

  And supply of the reactive gas with respect to reaction exhaust gas is normally performed so that reactive gas may not contact a catalyst. Specifically, the supply of the reactive gas can be performed, for example, on the downstream side of the position where the catalyst and the raw material gas are in contact with each other when viewed in the flow direction of the raw material gas and the reactive exhaust gas. In addition, a base on which the catalyst is supported by using a holder such as a holder for mounting the base material supporting the catalyst or a holder for gripping a part of the base material such as an edge of the base material supporting the catalyst. In the case of holding the material, the reactive gas is applied to the back side of the base material supporting the catalyst (for example, the base material in which at least a part of the edge is held by the holder) or the base material supporting the catalyst. It can also supply from the back surface side of the holding tool (for example, holding tool etc. which mount and hold | maintain a base material).

  From the viewpoint of effectively suppressing the generation of carbon-based byproducts, 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. , Equivalent amount or less, and more preferably ½ or less.

  And it is preferable to mix reaction exhaust gas and reactive gas at the temperature of 200 to 900 degreeC, for example. The mixing can be performed using any means such as diffusion, convection or stirring. Moreover, from the viewpoint of more effectively suppressing the generation of carbon-based byproducts, the temperature when mixing the reaction exhaust gas and the reactive gas is preferably 400 ° C. or higher, and preferably 600 ° C. or higher. Is more preferable, it is preferable that it is 880 degrees C or less, and it is more preferable that it is 860 degrees C or less.

(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, grows the carbon structure by chemical vapor deposition, and reaction gas generated in the growth furnace with hydroxy groups and And / or a reactive gas supply unit that supplies a reactive gas containing an aldehyde group-containing compound having 1 to 5 carbon atoms. The reactive gas supply unit may be provided in the growth furnace or provided outside the growth furnace (for example, in the exhaust pipe) as long as the reactive gas can be supplied to the reaction exhaust gas. Also good.

  And in the carbon structure manufacturing apparatus of the present invention, a reactive gas supply unit is provided, and a reactive gas containing a compound having 1 to 5 carbon atoms having a hydroxy group and / or an aldehyde group is supplied. Generation of carbon-based byproducts such as polycyclic aromatic hydrocarbons can be sufficiently suppressed. Accordingly, it is possible to sufficiently suppress the carbon-based by-product from adhering to the formed carbon structure and the manufacturing apparatus, and to prevent the product quality from being lowered and the exhaust pipe from being blocked.

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

<Example of carbon structure manufacturing apparatus>
In FIG. 1, an example of the manufacturing apparatus of the carbon structure of this invention is shown. A 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 prevention means 101 to 103, a growth unit 3, a cooling unit 4, An outlet purge unit 5, a transport unit 6, and connection units 7 to 9 are provided.

  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 internal spaces of the formation furnace 2a, the growth furnace 3a, and the cooling furnace 4a are in a state of being spatially connected by the connecting portions 7-9.

[Inlet purge section]
An inlet purge unit 1 is provided at the inlet of the manufacturing apparatus 100. The inlet purge unit 1 is a set of apparatuses for preventing external air from being mixed into 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 a purge gas.

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

  The purge gas is preferably an inert gas. In particular, the purge gas is preferably nitrogen from the viewpoints of safety, cost, purgeability, and the like.

[Formation unit]
The formation unit 2 is a set of devices for realizing the formation process. The formation unit 2 has a function of heating the environment around the catalyst formed on the surface of the substrate 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 a reducing gas, a reducing gas injection unit 2b for injecting the reducing gas into the formation furnace 2a, and a heater 2c for heating at least one of the catalyst and the reducing 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 reducing gas injection unit 2 b is provided at a position facing the catalyst carrying surface of the base material 20. The facing position is a position where the angle formed between the injection axis of each injection port and the normal line of the base material 20 is 0 ° or more and less than 90 °. That is, the direction of the gas flow ejected from the ejection port in the reducing gas ejection unit 2 b 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 substrate 20, and the catalyst can be efficiently reduced. As a result, the uniformity of the carbon structure grown on the substrate 20 can be improved, and the consumption of reducing gas can be reduced.

  The heater 2c is not limited as long as at least one of the catalyst and the reducing gas can be heated, 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 the surrounding environment of the catalyst is set as a raw material gas environment and at least one of the catalyst and the raw material gas is heated to grow a carbon structure. is there. The growth unit 3 includes a growth furnace 3a that is a furnace for maintaining 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, a catalyst, A heater 3c for heating at least one of the source gases and an exhaust hood 3d for exhausting the gas in the growth furnace 3a are included. 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 a reactive gas to the reaction exhaust gas generated in the growth furnace 3a. The growth unit 3 may have a catalyst activation material injection unit (not shown) for supplying the catalyst activation material. The source gas injection unit 3b may also serve as a catalyst activation material 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 process. The surrounding environment of the catalyst on the base material 20 is set as a raw material gas environment, and at least one of the catalyst and the raw material gas is heated. 20 is a furnace for obtaining a substrate 10 with a carbon structure obtained by growing a carbon structure on 20.

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

  At least one source gas injection unit 3b and exhaust hood 3d are provided, and the total gas flow rate injected from all source gas injection units 3b and the total gas flow rate exhausted from all exhaust hoods 3d are as follows: It is preferable that they are approximately the same amount or the same amount. By doing in this way, it can prevent that source gas flows out of growth furnace 3a, and gas outside growth furnace 3a flows into growth furnace 3a.

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

The reactive gas supply unit 16 and the reactive gas supply unit 17 are not in contact with the raw material gas before the reactive gas is used for the growth of the catalyst and the carbon structure, and after the reactive gas is used for the growth of the carbon structure. The reaction exhaust gas is arranged at a position where it is well mixed. Specifically, as shown in FIG. 2, the reactive gas supply unit 16 is installed below the substrate 10 with a carbon structure formed by growing a carbon structure on the substrate 20 in the growth furnace 3a. ing. More specifically, the reactive gas supply unit 16 shown in FIG. 2 is disposed 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 (see FIG. 2 comprises a pipe provided with holes for injecting reactive gas in the left-right direction). 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. .
In addition, from the viewpoint of further 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 includes a heater that heats the inside of the exhaust pipe 23 ( It is preferable that a heat insulating material (not shown) for keeping the exhaust pipe 23 warm is provided.

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

  The cooling unit 4 has a configuration combining a water cooling method and an air cooling method, a cooling furnace 4a for holding an inert gas, a cooling gas injection unit 4b for injecting an inert gas into a space in the cooling furnace 4a, and The water-cooled cooling pipe 4c is disposed so as to surround the space inside the cooling furnace 4a. Note that 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, oxidation of the carbon structure, the catalyst, and the base material after the growth step can be prevented.

[Outlet purge section]
At the outlet of the manufacturing apparatus 100, an outlet purge unit 5 having a structure substantially similar to that of the inlet purge unit 1 is provided. The outlet purge unit 5 is a set of apparatuses for preventing external air from being mixed into the inside from the outlet of the manufacturing apparatus 100. The outlet purge unit 5 has a function of making the ambient environment of the carbon structure-attached substrate 10 a purge gas environment.

  The outlet purge unit 5 prevents the outside air from being mixed into the cooling furnace 4a from the outlet by injecting the purge gas from above and below in a shower shape. The outlet purge unit 5 may be configured by a furnace or chamber for maintaining a purge gas environment, an injection unit for injecting purge gas, and the like.

  The purge gas is preferably an inert gas, and in particular, the purge gas is preferably nitrogen from the viewpoints of safety, cost, purgeability, and the like.

[Connection]
The connection portions 7 to 9 are a set of apparatuses for spatially connecting the space in 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 connection portions 7 to 9 include a furnace or a chamber that can block the environment around the base material and 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 prevention means 101 is disposed in the connection portion 7, and a mixed gas of the purge gas injected from the inlet purge unit 1 and the reducing gas injected from the reducing gas injection unit 2 b is exhausted. This prevents the purge gas from being mixed into the internal space of the formation furnace 2a and the reducing gas from being mixed into the inlet purge unit 1 side.

  The formation unit 2 and the growth unit 3 are spatially connected by a connection portion 8. A gas mixing prevention means 102 is disposed in the connection portion 8 to exhaust the reducing gas in the formation furnace 2a space, the source gas and the catalyst activation material in the growth furnace 3a space. Thereby, mixing of the raw material gas or the catalyst activator into the formation furnace 2a and the mixing of the reducing gas into the growth furnace 3a are prevented.

  The growth unit 3 and the cooling unit 4 are spatially connected by a connection portion 9. A gas mixing prevention means 103 is disposed in the connection portion 9 to exhaust a mixed gas of the raw material gas and the catalyst activation material in the growth furnace 3a space and the inert gas in the cooling furnace 4a space. Thereby, mixing of the raw material gas or the catalyst activation material into the cooling furnace 4a space and mixing of the inert gas into the growth furnace 3a space are prevented.

  The carbon structure manufacturing apparatus 100 may further include a heating unit that heats the connection portion 9 between the growth unit 3 and the cooling unit 4. This is because if the temperature in the vicinity of the outlet of the growth furnace 3a is lowered, the decomposition product of the source gas may become amorphous carbon and be deposited on the carbon structure.

  As a specific form of the heating means for heating the connection portion 9, for example, a seal gas ejected in the gas mixing prevention means 103 between the growth unit 3 and the cooling unit 4 may be heated. By heating the sealing gas, the outlet of the growth furnace 3a and the vicinity thereof can be heated.

[Gas mixing prevention means]
The gas mixing prevention means 101 to 103 are a set of apparatuses for realizing a function of preventing gases existing in the furnace space of each unit from mixing with each other. The gas mixing prevention means 101 to 103 are installed in the connection portions 7 to 9 that spatially connect the in-furnace spaces of the respective units. The gas mixing prevention means 101 to 103 include seal gas injection units 101b to 103b for injecting seal gas along the opening surfaces of the inlet and outlet of the base material in each furnace, and the mainly injected seal gas (and other nearby gas). At least one exhaust part 101a to 103a that sucks the gas (gas) so as not to enter each furnace and exhausts the gas outside the apparatus is provided.

  Since the seal gas is injected along the opening surface of the furnace, the seal gas can block the entrance / exit of the furnace and prevent the gas outside the furnace from being mixed into the furnace. Further, by exhausting the seal gas out of the apparatus, it is possible to prevent the seal gas from being mixed into the furnace.

  The seal gas is preferably an inert gas, and nitrogen is particularly preferable from the viewpoints of safety and cost. 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 The exhaust part may be arranged so as to face the seal gas injection part across 6a. In addition, it is preferable to arrange | position the seal gas injection parts 101b-103b and the exhaust parts 101a-103a so that the whole structure of the gas mixing prevention means 101-103 may become a symmetrical structure in the furnace length direction.

  For example, two seal gas injection parts may be arranged at both ends of one exhaust part, and the structure may be symmetrical in the furnace length direction with the exhaust part as the center. Moreover, 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 discharged from the exhaust units 101a to 103a are substantially the same amount. As a result, it is possible to prevent the gas from the spaces on both sides of the gas mixture preventing means 101 to 103 from being mixed with each other and to prevent the sealing gas from flowing into 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 seal gas flow and the gas flow in the growth furnace 3a from interfering with each other. Further, it is possible to prevent the gas flow from being disturbed by the inflow of the seal gas into the growth furnace 3a. Therefore, an apparatus suitable for continuous production of carbon structures can be realized.

  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. Moreover, the gas curtain apparatus which interrupts | blocks the spatial connection of each unit by inert gas injection may be sufficient.

[Transport unit]
The conveyance unit 6 is a set of apparatuses 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 driving unit 6b. The base material 20 is transported in the order of the formation unit 2, the growth unit 3, and the cooling unit 4 in each furnace space by the transport unit 6.

  The transport unit 6 is of a belt conveyor type, and transports the base material 20 on the surface of which the catalyst is supported from the formation furnace 2a space through the growth furnace 3a space to the cooling furnace 4a space. The conveyance unit 6 conveys the base material 20 by a mesh belt 6a driven by a belt driving unit 6b using, for example, an electric motor with a reduction gear. In the carbon structure manufacturing apparatus 100, the space between the formation furnace 2a and the growth furnace 3a, and the space between the growth furnace 3a and the cooling furnace 4a are separated by the connecting portions 8 and 9. Connected. Thereby, the mesh belt 6a which mounted the base material 20 can pass between each furnace.

  In addition, when the carbon structure manufacturing apparatus 100 is a device that manufactures a carbon structure in a continuous manner and includes a transport unit, the specific configuration is not limited to the above-described configuration, for example, The transfer unit may be a robot arm in a multi-chamber system, a robot arm driving device, or the like.

  In the manufacturing apparatus 100, 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 transported by the transport unit 6 with the substrate 20 having a catalyst on the surface. Are passed sequentially. In the meantime, the catalyst is reduced under the reducing gas environment in the formation unit 2, and the carbon structure grows on the surface of the base material in the raw material gas environment in the growth unit 3, and is cooled in the cooling unit 4. In the growth furnace 3a, the generation of carbon-based byproducts is suppressed by the supply of the reactive gas from the reactive gas supply units 16 and 17.

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

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

  And in the manufacturing apparatus 200, in the state which installed the base material which carry | supported the catalyst on the holder 211, reducing gas is supplied arbitrarily from the gas inlet 220, and a formation process is implemented. In addition, a raw material gas and an arbitrary catalyst activation material are supplied from the gas inlet 220, and a reactive gas is supplied from the reactive gas supply pipe 250 to carry out the growth process. Thereby, a carbon structure can be obtained while suppressing the generation of carbon-based byproducts.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to these Examples.

(Preparation of base material carrying catalyst)
A flat plate made of Fe-Cr alloy (manufactured by JFE Steel Corporation, SUS430, Cr: 18% by mass) having a length of 500 mm × width of 500 mm and a thickness of 0.6 mm was prepared as a base material. In addition, when the surface roughness of several places was measured using the laser microscope, arithmetic mean roughness Ra was 0.063 micrometer.
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 an alumina film forming coating agent.
And the above-mentioned coating agent for alumina film formation was apply | coated on the base material by dip coating in the environment of room temperature 25 degreeC, and relative humidity 50%. Specifically, the substrate was immersed in the coating agent for forming an alumina film, held for 20 seconds, pulled up at a lifting speed of 10 mm / second, and then air-dried for 5 minutes. Next, after heating for 30 minutes in 300 degreeC air environment, it cooled to room temperature. Thereby, 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.
And the iron film coating agent was apply | coated by the dip coating on the base material in which the above-mentioned alumina film was formed by the dip coating in the environment of room temperature 25 degreeC and 50% of relative humidity. Specifically, the substrate was dipped in the iron film coating agent and then held for 20 seconds, and the substrate was pulled up at a lifting speed of 3 mm / sec. Thereafter, it was air-dried for 5 minutes. Next, after heating for 30 minutes in an air environment at 100 ° C., the mixture was cooled to room temperature. This produced the base material (base material which carried the catalyst) which has a catalyst film with a film thickness of 3 nm.

Example 1
A substrate carrying a catalyst cut into a size of 40 mm in length and 40 mm in width is placed in the manufacturing apparatus 200 shown in FIG. 3, and a formation process and a growth process are sequentially performed to form carbon nanotubes (CNT). Manufactured.
Specifically, after the base material is set on the holder 211, the formation process is performed 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. Source gas (carbon compound: ethylene, catalyst activation material: water) having the composition shown and a reactive gas were supplied at a flow rate shown in Table 1 for 10 minutes, and the operation of growing CNTs 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 a region S indicated by a two-dot chain line in FIG. 3 in the reaction furnace 210 (immediately upstream of the gas discharge port 230). Further, although not shown, a control device including a flow rate control valve and a pressure control valve is attached at an appropriate position in order to control the gas flow rate.
And the by-product adhesion rate per unit area of a by-product collection tube was calculated by measuring the weight of the by-product adhering to the inner side of the by-product collection tube. 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. Asked. The results are shown in Table 1.

(Comparative Examples 2-3)
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 the by-product was attached in the same manner as in Example 1. The speed was determined. The results are shown in Table 1.

From Table 1, in Example 1 using methanol (gas), Comparative Example 1 in which no reactive gas was used, a gas in 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 a gas added with air so that oxygen is 5% by volume with respect to the total amount is used as a reactive gas, the by-product deposition rate is up to 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 are all yield: 2.0 mg / cm ² , G / D ratio: 6.3, and specific surface area: 1100 m ^2. / G. From this, it was confirmed that CNTs having equivalent characteristics could be produced.

(Experimental example)
In the manufacturing apparatus 200 in which the base material was not installed, the raw material gas and the reactive gas were flowed under the same conditions as in the case of growing CNTs on the base material in Example 1 and Comparative Examples 1 to 3. And the gas component of the by-product collection pipe | tube vicinity was extract | collected, and the composition was measured using the gas chromatograph mass spectrometer (GCMS). The results are shown in Table 2.

Table 2 shows that formaldehyde (CH ₂ O) is generated by the thermal decomposition of methanol, and it is possible that compounds having a hydroxy group and / or an aldehyde group contribute to the suppression of PAHs. It was done.

  ADVANTAGE OF THE INVENTION According to this invention, when manufacturing a carbon structure by CVD method, the production | generation of a carbon-type by-product can fully be suppressed.

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

Claims (8)

Supplying a source gas containing a carbon compound to the catalyst and growing a carbon structure by chemical vapor deposition (A);
Supplying a reactive gas containing a compound having 1 to 5 carbon atoms having a hydroxy group and / or an aldehyde group to the reaction exhaust gas generated in the step (A);
The manufacturing method of the carbon structure containing this.   The manufacturing method of the carbon structure of Claim 1 whose said compound is a C1-C1 compound which has a hydroxyl group and / or an aldehyde group.   The method for producing a carbon structure according to claim 1 or 2, 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, wherein the carbon structure is a carbon nanotube and / or graphene. A growth furnace for supplying a raw material gas containing a carbon compound to the catalyst and growing a carbon structure by chemical vapor deposition;
A reactive gas supply unit that supplies a reactive gas containing a compound having 1 to 5 carbon atoms having a hydroxy group and / or an aldehyde group to the reaction exhaust gas generated in the growth furnace;
An apparatus for producing a carbon structure, comprising:   The apparatus for producing a carbon structure according to claim 5, wherein the compound is a C 1 compound having a hydroxy group and / or an aldehyde group.   The apparatus for producing a carbon structure according to claim 5 or 6, wherein the compound is at least one selected from the group consisting of methanol, formaldehyde, and formic acid.   The carbon structure manufacturing apparatus according to claim 5, wherein the carbon structure is a carbon nanotube and / or graphene.

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