Method for producing carbon nanotube aggregates

Abstract

The purpose of the present invention is to provide a manufacturing method for carbon nanotube aggregates, which makes it possible to efficiently produce high-quality carbon nanotubes aggregates.　The present invention is a manufacturing method in which carbon nanotube aggregates are grown on a substrate having a catalyst on the surface. In the manufacturing method, a substrate is continuously transported using a transport unit for transporting the substrate, by screw rotation, in each of: a formation unit for performing a formation step in which a catalyst on the substrate is put in a reduction state; and a growth unit for performing a growth step in which carbon nanotube aggregates are grown. Moreover, when implementing the formation step and the growth step, gas environments in these steps are prevented from being mixed with each other while both steps are implemented.

Description

[Technical Field]

[0001] The present invention relates to a method for producing an aggregate of carbon nanotubes, and in particular to a method for producing an aggregate of carbon nanotubes having a specific surface area of ​​600 m 2 The present invention relates to a manufacturing method for manufacturing a high-quality aggregate of carbon nanotubes having a density of 1 / g or more. [Background technology]

[0002] In recent years, nanocarbon materials such as carbon nanotubes (hereinafter sometimes referred to as "CNTs") have been attracting attention as materials with excellent electrical conductivity, thermal conductivity, and mechanical properties. Although nanocarbon materials are recognized to have the potential to exhibit excellent properties, they have generally been more expensive than other materials due to their high manufacturing costs.

[0003] Therefore, various attempts have been made to efficiently produce nanocarbon materials. For example, Patent Document 1 proposes a method for producing CNTs by combining a formation process in which a catalyst is reduced under a reducing gas atmosphere and a growth process in which CNTs are grown on the catalyst under a raw material gas atmosphere, while preventing the two atmospheres from intermixing. To improve production efficiency, a substrate with a large surface area per volume, such as a powder, is advantageous. However, transporting powdered substrates using a belt conveyor system presents a problem: insufficient stirring of the substrate results in significant uneven CNT growth between substrates. Furthermore, Patent Document 2 proposes a nanocarbon production method that involves stirring and moving a catalyst within a reaction tube equipped with a catalyst activation zone, a nanocarbon synthesis zone, and a cooling zone using a conveying means such as a belt conveyor. However, because the ambient gases in each zone cannot be spatially separated, the method requires either timed switching between the reducing gas and raw material gas or allows the gases to be mixed. This has prevented the practical continuous production of high-quality nanocarbons such as single-walled carbon nanotubes. Furthermore, for example, Patent Document 3 studies a method for producing nanocarbon, which includes continuously supplying a hydrocarbon and a catalyst using a screw feeder so that the two are in contact with each other in a countercurrent or opposing flow state. In this study, methane is used as the hydrocarbon of the raw material gas, and in this case, a catalyst reduction step is not necessarily required, and there is no need to divide the inside of the reaction tube into zones. However, since mainly multi-walled carbon nanotubes are synthesized and the growth rate is slow, it has not yet been possible to continuously produce high-quality nanocarbon such as single-walled carbon nanotubes with high production efficiency. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5471959 specification [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-241104 [Patent Document 3] Patent No. 5285730 specification Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-described conventional methods for producing nanocarbon materials have room for improvement in terms of further improving the quality and production efficiency of the resulting nanocarbon materials.

[0006] Therefore, an object of the present invention is to provide a method for producing an aggregate of carbon nanotubes, which can efficiently produce an aggregate of carbon nanotubes with high quality. [Means for solving the problem]

[0007] The present inventors have conducted extensive research with the aim of solving the above problems. As a result, the present inventors have newly discovered that, when producing a CNT aggregate, it is possible to efficiently produce a high-quality CNT aggregate by separately performing a formation step and a growth step in this order and transporting a substrate having a catalyst on its surface by screw rotation in these steps, and have completed the present invention.

[0008] That is, the present invention has an object to advantageously solve the above-mentioned problems, and the CNT aggregate production method of the present invention is a method for producing a CNT aggregate by depositing a carbon nanotube having a specific surface area of ​​600 m on a substrate having a catalyst on its surface. 21. A method for producing a carbon nanotube aggregate for growing a carbon nanotube aggregate of 1 / g or more, the method comprising: a formation unit for realizing a formation step of making an environment around the catalyst a reducing gas environment and heating at least one of the catalyst and the reducing gas; a growth unit for realizing a growth step of making an environment around the catalyst a raw material gas environment and heating at least one of the catalyst and the raw material gas to grow the carbon nanotube aggregate; a connection part for spatially connecting an inner furnace space of the formation unit with an inner furnace space of the growth unit; and a connecting part for connecting the substrate to an inner furnace space of the formation unit by screw rotation in the inner furnace space of the formation unit. and a second transport unit that transports the substrate in the furnace space of the growth unit by screw rotation, the first transport unit and the second transport unit being configured as a single common unit and / or separate units, and a gas mixing prevention device that prevents gases from mixing between the furnace space of the formation unit and the furnace space of the growth unit, and the formation step and the growth step are performed while continuously transporting the substrate and preventing gas environments in the steps from mixing with each other. Such a manufacturing method enables efficient production of high-quality CNT aggregates.

[0009] Furthermore, in the CNT aggregate production method of the present invention, it is preferable that the formation unit and the growth unit are separate components and connected in series by the connection part. According to such a production method, it is possible to easily optimize the conditions in each of the formation step and the growth step, and it is possible to further improve the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate.

[0010] Furthermore, in the CNT aggregate production method of the present invention, it is preferable that the gas mixing prevention device controls the airflow to prevent gases from mixing with each other between the furnace space of the formation unit and the furnace space of the growth unit. According to such a production method, the reduction of the catalyst in the formation step is less likely to be hindered, and the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate can be further improved.

[0011] In the CNT aggregate manufacturing method of the present invention, it is preferable to carry out at least one of the following: in the formation step, the reducing gas is continuously supplied so that the base material transported by the first transport unit and the reducing gas come into contact with each other in a countercurrent and countercurrent state in the furnace space of the formation unit; and in the growth step, the raw material gas is continuously supplied so that the base material transported by the second transport unit and the raw material gas come into contact with each other in a countercurrent and countercurrent state in the furnace space of the growth unit. According to such a manufacturing method, it is possible to further improve the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate.

[0012] In the CNT aggregate production method of the present invention, it is preferable that the raw material gas environment in the growth step is a high carbon concentration environment and contains a catalytic activation material. By growing CNTs in a high carbon concentration environment containing a catalytic activation material in the growth step, it is possible to grow CNTs while maintaining catalytic activity for a long period of time, and therefore it is possible to further improve the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate.

[0013] In the CNT aggregate production method of the present invention, the raw material gas environment preferably contains ethylene and carbon dioxide as a catalyst activation material. By carrying out the growth step in such an environment, the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate can be further improved.

[0014] In the CNT aggregate production method of the present invention, the substrate has an apparent density of 2.0 g / cm 3 It is preferable that the substrate has an apparent density of 2.0 g / cm or more. 3 With the above particles, the resulting CNT aggregate can be made long. The "apparent density" of the support means the mass per unit volume including the voids (closed pores) when the support is a particle having voids inside. The "apparent density of the support" can be measured according to the pycnometer method.

[0015] Furthermore, in the CNT aggregate production method of the present invention, it is preferable that the base material contains one or more elements of Al, Si, and Zr. By using a base material containing one or more elements of Al, Si, and Zr, it is possible to further improve the production efficiency of the CNT aggregate.

[0016] Furthermore, the CNT aggregate production method of the present invention preferably comprises a catalyst layer forming step of forming a catalyst layer on the substrate, a separation and recovery step of separating the carbon nanotube aggregate from the substrate and separately recovering the substrate and the carbon nanotube aggregate, and a recycling step of making the substrate reusable by oxidizing and removing carbon on the recovered substrate. By carrying out such a separation and recovery step and recycling step, it is possible to further improve the production efficiency of the CNT aggregate. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a method for producing an aggregate of carbon nanotubes, which can efficiently produce a high-quality CNT aggregate. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a diagram for explaining a schematic configuration of an apparatus capable of carrying out a CNT aggregate manufacturing method according to an example of the present invention. [Figure 2]FIG. 2 is a schematic diagram for explaining the flow of raw material gas in a growth unit provided in an apparatus capable of carrying out a CNT aggregate manufacturing method according to an example of the present invention. [Figure 3] FIG. 10 is a diagram for explaining a schematic configuration of an apparatus capable of carrying out a CNT aggregate manufacturing method according to another example of the present invention. [Figure 4] 4 is a diagram for explaining a schematic configuration of an example of components of a gas mixing prevention device that can be provided in the device explained in FIG. 3.

[0023] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 2 In the following description, based on the progression of the treatment from the formation step to the growth step, an optional cooling step, and a separation step, an operation on the front side or a component part of the production apparatus that performs such an operation will be described as an operation or component part on the "front-stage side," and an operation or component part on the back side will be described as an operation or component part on the "back-stage side."

[0020] The method for producing a CNT aggregate of the present invention is to form a CNT aggregate having a specific surface area of ​​600 m on a substrate having a catalyst on its surface. 2 The method for producing a CNT aggregate of the present invention is a method for carrying out a formation step and a growth step using a CNT production apparatus having the following components, while continuously transporting a base material and preventing the gas environments in the following steps from being mixed with each other. A formation unit that realizes a formation step in which the surrounding environment of the catalyst is made into a reducing gas environment and at least one of the catalyst and the reducing gas is heated. A growth unit that realizes a growth step in which the surrounding environment of the catalyst is made into a source gas environment and at least one of the catalyst and the source gas is heated to grow an aggregate of carbon nanotubes. A connection section that spatially connects the furnace space of the formation unit with the furnace space of the growth unit. a first conveying unit that conveys a substrate by screw rotation in the furnace space of the formation unit, and a second conveying unit that conveys a substrate by screw rotation in the furnace space of the growth unit, the first conveying unit and the second conveying unit being capable of being implemented as one common unit and / or separate units; A gas mixing prevention device that prevents gases from mixing between the furnace space of the formation unit and the furnace space of the growth unit.

[0021] <Substrate with catalyst on its surface> The substrate used in the production method of the present invention, which constitutes the substrate having a catalyst on its surface, can be formed by supporting a catalyst on the substrate.

[0022] <<Base material>> The substrate is a member capable of supporting a catalyst for synthesizing CNTs on its surface, and is not particularly limited, and members made of any material can be used. Among these, the substrate is preferably made of a ceramic material containing at least one element selected from Al, Si, and Zr. Furthermore, the substrate is preferably made of a metal oxide containing at least one element selected from Al, Si, and Zr, and is more preferably zirconium dioxide (ZrO2). The substrate preferably has a particulate shape with an aspect ratio of less than 5. The "aspect ratio" of the substrate particles can be calculated by averaging the values ​​(major axis / width perpendicular to the major axis) of a number of arbitrarily selected particles on a microscope image. Furthermore, the substrate particles should have an apparent density of 2.0 g / cm. 3 It is preferable that the concentration is 3.8 g / cm or more. 3 It is preferable that the concentration is 5.8 g / cm or more. 3 More preferably, it is 8.0 g / cm or more. 3Preferably, the apparent density of the particulate substrate is equal to or greater than the lower limit, allowing the resulting CNT aggregate to be elongated. Furthermore, if the apparent density of the particulate substrate is equal to or less than the upper limit, the substrate particles are easy to handle, further improving the production efficiency of the CNT aggregate. Furthermore, the particle diameter of the substrate particles is preferably equal to or greater than 0.05 mm, more preferably equal to or greater than 0.3 mm, and preferably equal to or less than 10 mm, more preferably equal to or less than 2 mm, and even more preferably equal to or less than 1 mm. If the particle diameter of the substrate particles is equal to or greater than the lower limit, the resulting CNT aggregate can be elongated. Furthermore, if the particle diameter of the substrate particles is equal to or less than the upper limit, the production efficiency of the CNT aggregate can be further improved. The "particle diameter" of the substrate particles refers to the volume-average particle diameter D50. The volume-average particle diameter D50 represents the particle diameter at which the cumulative volume calculated from the smallest diameter side in the particle size distribution (volume-based) of the substrate particles measured by laser diffraction is 50%.

[0023] <<Catalyst>> The catalyst supported on the substrate is not particularly limited, and examples thereof include catalyst components such as nickel (Ni), iron (Fe), cobalt (Co), and molybdenum (Mo). Among these, from the viewpoint of further improving the production efficiency of CNT aggregates, it is preferable that the catalyst component contains at least one metal selected from nickel (Ni), iron (Fe), cobalt (Co), and molybdenum (Mo). Furthermore, optionally, an underlayer made of a material such as aluminum oxide, titanium oxide, titanium nitride, or silicon oxide can be provided as a base for supporting the catalyst on the substrate.

[0024] <<Method for preparing a substrate having a catalyst on its surface>> The method for supporting a catalyst (or catalyst layer) on a substrate surface (catalyst layer formation process) is not particularly limited, and any existing method can be used. Among these, when base particles are used as the substrate, a method using a rotary drum coating device equipped with a substantially cylindrical rotating drum is preferred. This method includes a spraying process in which a substrate is placed inside a substantially cylindrical rotating drum and the rotating drum is rotated around an inclined axis to agitate the base particles while spraying a catalyst solution containing the above-mentioned catalyst components onto the agitated base particles, and a drying process in which a dry gas is introduced into the rotating drum to bring the dry gas into contact with the base particles sprayed with the catalyst solution. At least a portion of the period during which the agitation process is performed overlaps with at least a portion of the period during which the spraying process is performed. When a base layer is formed on the substrate surface and then the catalyst is supported, the same spraying and drying processes as described above can be performed using a solution containing components that can constitute the base layer and the base particles prior to spraying and drying the catalyst solution, thereby obtaining base particles having a base layer on their surfaces. Then, by subjecting the base particles having a base layer on their surface to the above-mentioned spraying process and drying process, base particles having a base layer and a catalyst (or catalyst layer) supported on their surface in this order can be obtained.

[0025] In addition, when base particles are used as the base material, methods for preparing a base material having a catalyst (or catalyst layer) on its surface include, in addition to the above, a method including a step of spraying a catalyst solution onto the base material particles while subjecting them to centrifugal swirling flow and vertical floating flow.

[0026] <Reducing gas> The reducing gas is a gas that has at least one of the effects of reducing the catalyst, promoting catalyst atomization, and improving catalyst activity. Examples of the reducing gas that can be used include hydrogen gas, ammonia, water vapor, and mixtures thereof. Furthermore, a mixed gas obtained by mixing hydrogen gas with an inert gas such as helium gas, argon gas, or nitrogen gas can also be used as the reducing gas. The reducing gas is generally used in the formation step, but may also be used in the growth step as appropriate.

[0027] <Source gas> Examples of raw material gases used in the synthesis of CNT aggregates include hydrocarbons such as methane, ethane, ethylene, propane, butane, pentane, hexane, heptane, propylene, and acetylene; lower alcohols such as methanol and ethanol; and oxygen-containing compounds with a low carbon number such as acetone and carbon monoxide. These gases can also be used in combination. Furthermore, the raw material gases may be diluted with the above-mentioned inert gases.

[0028] Here, the raw material gas preferably contains ethylene. Heating ethylene within a predetermined temperature range (700°C or higher and 900°C or lower) promotes the decomposition reaction of ethylene, enabling rapid growth of CNTs when the decomposition gas comes into contact with the catalyst. However, if the thermal decomposition time is too long, the ethylene decomposition reaction proceeds too quickly, causing catalyst deactivation and carbon impurities to adhere to the CNT aggregate. In the method for producing a CNT aggregate of the present invention, a thermal decomposition time of 0.5 seconds to 10 seconds is preferred for an ethylene concentration of 0.1% by volume to 40% by volume. If the thermal decomposition time is less than 0.5 seconds, the ethylene will not be thermally decomposed sufficiently, making it difficult to rapidly grow a CNT aggregate with a high specific surface area. If the time is longer than 10 seconds, the ethylene will be decomposed too quickly, generating a large amount of carbon impurities, which will deactivate the catalyst and reduce the quality of the CNT aggregate. The thermal decomposition time can be calculated using the following formula. (Pyrolysis time) = (heating flow channel volume) / {(raw material gas flow rate) × (273.15 + T) / 273.15} Here, the heated flow channel volume is the volume of the flow channel heated to a predetermined temperature T°C through which the raw material gas passes before contacting the catalyst, and the raw material gas flow rate is the flow rate at 0°C and 1 atm.

[0029] <Catalyst activator> A catalytic activator may be added in the CNT growth process. Addition of the catalytic activator can further improve the production efficiency and quality of the CNT aggregate. The catalytic activator used here is generally an oxygen-containing substance that does not significantly damage CNTs at the growth temperature. Examples of the catalytic activator include water, hydrogen sulfide; oxygen, ozone, nitrogen oxide, carbon monoxide, carbon dioxide, and other low-carbon oxygen-containing compounds; alcohols such as ethanol and methanol; ethers such as tetrahydrofuran; ketones such as acetone; aldehydes; esters; nitrogen oxide; and mixtures thereof. Among these, water, oxygen, carbon dioxide, carbon monoxide, or tetrahydrofuran are preferred, with carbon dioxide being more preferred. Growing CNTs in a high-carbon environment containing the catalytic activator in the growth process allows CNTs to grow while maintaining catalytic activity for a long period of time, thereby further improving the quality of the resulting CNT aggregate and the production efficiency of the CNT aggregate. Furthermore, when the source gas contains ethylene, the presence of carbon dioxide as a catalyst activator can further improve the quality of the resulting CNT aggregate and the production efficiency of the CNT aggregate. The reasons for this are presumed to be as follows. First, it has been found that ethylene as a carbon source and carbon dioxide as a catalyst activator are relatively inactive in the CNT synthesis reaction. Therefore, when a gas mixture containing the above gases passes through a layer made of substrates with catalysts on their surfaces, i.e., a layer made of an aggregate of substrates continuously transported by screw rotation, the concentration of each gas decreases very slowly due to the CNT synthesis reaction, and the concentration distribution of each gas within the layer can be relatively uniform. As a result, CNT growth between substrates is also uniform, making it possible to increase production efficiency.

[0030] The amount of catalyst activation material added in the growth step, for example, in the case of carbon dioxide, may be 0.5% by volume or more of the atmosphere in the growth step, preferably 4% by volume or more, more preferably 5% by volume or more, and is usually 40% by volume or less.

[0031] <High carbon concentration environment> A high carbon concentration environment refers to an atmosphere in the growth process (hereinafter also referred to as the "raw material gas environment") in which 0.1 vol % or more of the atmosphere is raw material gas. The ratio of raw material gas in a high carbon concentration environment can be, for example, 40 vol % or less. Furthermore, the ratio of raw material gas in a high carbon concentration environment is preferably 4 vol % or more, more preferably 5 vol % or more, even more preferably 10 vol % or more, and preferably 30 vol % or less. Here, by including a catalyst activating material in the raw material gas environment, catalytic activity is significantly improved, so that the catalyst does not lose activity even in a high carbon concentration environment, making it possible to grow CNT aggregates for a long period of time and significantly improving the growth rate.

[0032] <Reaction temperature> The reaction temperature for growing the CNT aggregate is not particularly limited, and can be, for example, 400° C. or higher and 1100° C. or lower. Furthermore, when the raw material gas contains ethylene, the temperature is preferably 700° C. or higher and 900° C. or lower.

[0033] <Formation process> The formation process involves creating a reducing gas environment around the catalyst supported on the substrate and heating at least one of the catalyst and the reducing gas. This process produces at least one of the following effects: reduction of the catalyst, promotion of catalyst microparticulation suitable for CNT growth, and improvement of catalyst activity.

[0034] In the formation process, it is preferable that the reducing gas be continuously supplied so that the substrate transported by the first transport unit and the reducing gas come into contact with each other in a countercurrent and counterflow state within the furnace space of the formation unit. This manufacturing method can further improve the quality of the resulting CNT aggregate and the production efficiency of the CNT aggregate. More specifically, by bringing the substrate transported by the first transport unit into contact with the reducing gas in a countercurrent and counterflow state, the substrate and the reducing gas can be in contact with each other throughout the period the substrate is transported through the formation unit, thereby efficiently ensuring the contact time between the two. Furthermore, by configuring the contact direction to be realized in both countercurrent and countercurrent directions rather than selecting either one, the contact efficiency between the two can be improved. Furthermore, in this configuration, by appropriately arranging the introduction and exhaust positions of the reducing gas, the residence time of the reducing gas within the manufacturing apparatus can be optimized. This also further improves the quality of the resulting CNT aggregate and the production efficiency of the CNT aggregate.

[0035] The temperature of the catalyst support or the reducing gas atmosphere in the formation step is preferably 400° C. or more and 1100° C. or less. The formation step can be carried out for 3 minutes or more and 120 minutes or less.

[0036] <Growth process> The growth step is a step in which the surrounding environment of the catalyst, which has been made suitable for producing a CNT aggregate by the formation step described above, is made into a raw material gas environment, and at least one of the catalyst and the raw material gas is heated, thereby growing a CNT aggregate. The production method of the present invention is characterized in that both steps are carried out while the substrate is continuously transported by screw rotation, preventing the gas environments in the formation step and the growth step from mixing with each other. This makes it possible to further improve the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate.

[0037] In the growth step, as in the formation step described above, it is preferable that the raw material gas be continuously supplied so that the base material transported by the second transport unit and the raw material gas come into contact with each other in a countercurrent and countercurrent state in the furnace space of the growth unit. This can further improve the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate. Furthermore, by appropriately arranging the introduction position and exhaust position of the raw material gas, it is possible to optimize the residence time of the raw material gas in the manufacturing apparatus. This can also further improve the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate.

[0038] <Cooling process> Optionally, a cooling step can be carried out after the growth step. In the cooling step, the CNT aggregate, catalyst, and substrate obtained in the growth step are cooled in an inert gas environment. Since the CNT aggregate, catalyst, and substrate are in a high-temperature state after the growth step, they tend to be easily oxidized when placed in an oxygen-containing environment. Therefore, it is preferable to cool the aligned CNT aggregate, catalyst, and substrate to 400°C or less, more preferably 200°C or less, in an inert gas environment.

[0039] <Separation and recovery process> In the separation and recovery step, the carbon nanotube aggregate is separated from the substrate, and the substrate and the carbon nanotube aggregate are recovered separately. The recovery method is not particularly limited, and any known method can be used. Among them, it is preferable to use a separation and recovery method (for example, see International Publication No. 2019 / 188979) that utilizes an external force and a fluid flow as a drag force against the external force (for example, an air vortex formed by a centrifugal force and an air flow as a drag force against the centrifugal force).

[0040] <Reuse process> In the recycling process, the carbon on the recovered substrate is oxidized and removed, making the substrate reusable. The method for oxidative removal is not particularly limited, and examples thereof include a method of heating the substrate while circulating air. By carrying out such a recycling process, the cost associated with the substrate can be reduced.

[0041] <Attributes of the CNT aggregate> The specific surface area of the CNT aggregate obtained by the production method of the present invention is the value measured by the method of Brunauer, Emmett, and Teller from the adsorption / desorption isotherm at 77 K of liquid nitrogen for CNTs that have not been subjected to opening treatment. For example, the specific surface area of the CNT aggregate can be measured using a BET specific surface area measuring device conforming to JIS Z8830. The specific surface area of the CNT obtained by the present invention is 600 m 2 / g or more, preferably 800 m 2 / g or more, preferably 2600 m 2 / g or less, and more preferably 1400 m 2 / g or less. Further, in the case of the opened CNT aggregate, the specific surface area is preferably 1300 m 2 / g or more.

[0042] (CNT manufacturing apparatus) FIG. 1 is a diagram for explaining the schematic configuration of an apparatus capable of implementing the method for manufacturing a CNT aggregate according to an example of the present invention. According to the CNT aggregate manufacturing apparatus 100 shown in FIG. 1, the method for manufacturing the CNT aggregate of the present invention can be implemented. Such a CNT aggregate manufacturing apparatus 100 includes a formation unit 102, a growth unit 104, a transport unit 107 for transporting a substrate until it passes from the formation unit 102 to the growth unit 104, a connection unit 108 that spatially connects the formation unit 102 and the growth unit 104 to each other, and a gas mixing prevention device for preventing gas from mixing with each other between the formation unit 102 and the growth unit 104. Further, the CNT aggregate manufacturing apparatus 100 includes a configuration such as an inlet purge device 101 arranged in the front stage of the formation unit 102, an outlet purge device 105 arranged in the rear stage of the growth unit 104, and a cooling unit 106 arranged in the rear stage of the outlet purge device 105.

[0043] <Inlet purge device> The inlet purge device 101 consists of a set of devices to prevent external air from entering the furnace through the substrate inlet. Its function is to replace the ambient environment of the substrates transported into the CNT aggregate manufacturing apparatus 100 with a purge gas. Examples include a furnace or chamber for storing the purge gas and an injection device for injecting the purge gas. The purge gas is preferably an inert gas, and nitrogen is particularly preferred from the standpoints of safety, cost, and purgeability. It may contain a small amount of hydrogen to improve catalytic activity. When the substrate inlet is always open, the purge gas injection device is preferably implemented as a gas curtain device consisting of an air supply device configured to inject purge gas in a shower-like manner from above and below, and is configured to prevent external air from entering through the inlet of the CNT aggregate manufacturing apparatus 100. In the embodiment shown in Figure 1, the inlet purge device 101 is attached to a connection 109 connecting the formation furnace 102a to the antechamber 113, which introduces the substrates into the system via a hopper 112.

[0044] <Formation Unit> The formation unit 102 comprises a set of devices for performing the formation process. The formation unit 102 creates a reducing gas environment around the catalyst formed on the surface of the substrate, and heats at least one of the catalyst and the reducing gas. The formation unit 102 may be configured, for example, with a formation furnace 102a for holding the reducing gas, a reducing gas injection device 102b for injecting the reducing gas, a heating device 102c for heating at least one of the catalyst and the reducing gas, and an exhaust device 102d for discharging the gas in the furnace to the outside of the system. The heating device 102c is not particularly limited and may be implemented, for example, by a resistance heater, an infrared heater, an electromagnetic induction heater, or the like. The heating device 102c may also heat the system so that the temperature inside the formation furnace is between 400°C and 1100°C. Furthermore, the exhaust device 102d is a component for exhausting the reducing gas from the furnace, including a reducing gas exhaust port disposed on the side of the furnace body of the formation furnace 102a. The formation unit 102 preferably has at least one reducing gas exhaust port, and may have multiple reducing gas exhaust ports.

[0045] <Growth Unit> The growth unit 104 comprises a set of devices for performing the growth process. The growth unit 104 transforms the surrounding environment of the catalyst, which has been made suitable for producing CNT aggregates by the formation process, into a source gas environment, and grows CNT aggregates by heating at least one of the catalyst and the source gas. Specifically, the growth unit 104 may be composed of a growth furnace 104a for maintaining the source gas environment, a source gas injection device 104b for injecting the source gas, a heating device 104c for heating at least one of the catalyst and the source gas, and an exhaust device 104d for exhausting the gas in the furnace to the outside. The heating device 104c is not particularly limited and may be implemented, for example, by a resistance heater, an infrared heater, or an electromagnetic induction heater. Furthermore, although not shown, the growth unit 104 preferably includes a catalyst activation material addition device. The exhaust device 104d is a component for exhausting the source gas in the furnace to the outside, including a source gas exhaust port located on the side of the furnace body of the growth furnace 104a. The growth unit 104 preferably has at least one source gas exhaust port, and may have a plurality of source gas exhaust ports.

[0046] The flow of source gas in the growth unit will now be described with reference to FIG. 2. For clarity, the transfer unit is omitted from FIG. 2. Components that perform the same functions as those shown in FIG. 1 are denoted by the same reference symbols as those used in FIG. 1. Components that perform essentially the same functions as those shown in FIG. 1 but differ slightly in their arrangement, etc., are denoted by the same reference symbols as those used in FIG. 1 with an ''' added. The growth furnace 104a shown in FIG. 2 includes multiple heating devices 104c'. The furnace body is equipped with two source gas inlets G1 and G2 on its side, and three source gas exhaust ports Ex1 to Ex3: one in the gap between them, one on the upstream side, and one on the downstream side in the substrate transport direction. The two source gas inlets G1 and G2 flow in the forward and backward directions relative to the substrate transport direction due to the suction force generated by the exhaust from the source gas exhaust ports Ex1 to Ex3. As a result, the substrate transported along the transport direction and the source gas come into contact with each other in a counterflow and counterflow state. Furthermore, by adjusting the introduction speed and introduction balance of the raw material gas from the raw material gas inlets G1 and G2, and the exhaust speed and exhaust balance at the raw material gas exhaust outlets Ex1 to Ex3, it is possible to easily optimize the residence time of the raw material gas in the system. As a result, the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate can be further improved. In addition, forming such a gas flow makes it possible to realize the function of preventing mutual mixing of gases in the furnace space between adjacent units by controlling the airflow of the gas mixing prevention device 103. Although the growth unit has been used as a specific example in this description, by applying a similar configuration to the formation unit, similar control can be easily achieved for the behavior of the reducing gas within the formation unit.

[0047] <Catalyst activator material adding device> The catalytic activator adding device is a complete set of equipment for adding the catalytic activator to the source gas or directly adding the catalytic activator to the surrounding environment of the catalyst in the growth furnace space. The catalytic activator adding device is not particularly limited to a specific device for supplying the catalytic activator, and may include a supply system capable of supplying the catalytic activator using a bubbler, vaporizing a solution containing the catalytic activator, supplying the gas as is, or liquefying and vaporizing a solid catalytic activator. Such a supply system may include, for example, a vaporizer, a mixer, an agitator, a diluter, a sprayer, a pump, a compressor, and the like. Furthermore, a device for measuring the concentration of the catalytic activator may be provided in the supply pipe of the catalytic activator. Feedback control using this output value allows for stable supply of the catalytic activator with little change over time.

[0048] <Transport unit> The transport unit 107 is a unit that continuously transports the substrate 111 by screw rotation. For example, the transport unit 107 can be implemented as a screw conveyor. The screw conveyor can be implemented by a screw blade 107a and a drive device 107b, such as a motor, that can rotate the screw blade to perform the substrate transport function. As shown in FIG. 1, the substrate can be introduced into the device from outside the system via a hopper 112, for example. The area around the drive device 107b can be heated by a heating device 114 that is configured to heat the system at a temperature lower than the heating temperature in the formation unit. The diameter and winding pitch of the screw blades that make up the screw conveyor can be adjusted as desired depending on the size of the substrate used, etc.

[0049] 1 illustrates a configuration in which the first transport unit, which transports the substrate in the furnace space of the formation unit 102 by screw rotation, and the second transport unit, which transports the substrate in the furnace space of the growth unit 104 by screw rotation, are implemented as a single common unit, that is, screw blade 107a and drive device 107b. As will be described later with reference to FIG. 3, the first transport unit and the second transport unit can also be implemented as separate units. Alternatively, there can be two separate transport units, with the first transport unit being the first transport unit and the second transport unit being a single common unit.

[0050] <Gas contamination prevention device> The gas mixing prevention device 103 is installed in the connection part 108 that spatially connects the formation unit 102 and the growth unit 104 to each other, and consists of a set of devices that realize the function of preventing gases from mixing with each other in the furnace spaces of the formation unit 102 and the growth unit 104. The gas mixing prevention device 103 is not particularly limited, and can be implemented by a gate valve device or rotary valve device that can mechanically block the spatial connection between each unit except when the substrate is being moved from one unit to another, a gas curtain device consisting of an air supply device configured to be able to inject purge gas, an exhaust device that exhausts gases present in the connection part 108, inside the formation unit 102 near the connection part 108, and inside the growth unit 104 near the connection part 108 to the outside of the system, or the like. In particular, it is preferable that the gas mixing prevention device 103 has an exhaust device 103a that sucks in at least one of the reducing gas flowing in from the formation unit 102 side and the raw material gas flowing in from the growth unit 104 side and exhausts it to the outside of the CNT aggregate manufacturing apparatus 100. Furthermore, it is preferable that the gas mixing prevention device 103 also has, in addition to the exhaust device 103a, a purge gas injection device 103b that injects a purge gas (seal gas) along the opening surface of the connection part 108, and the exhaust device 103a sucks in the purge gas and exhausts it to the outside of the manufacturing apparatus. According to the CNT aggregate manufacturing apparatus 100 having such a configuration, the reduction of the catalyst in the formation step is less likely to be hindered, and it is possible to further improve the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate. Furthermore, the screw conveyor, which is the transport unit 107, straightens the flow of gas in the furnace space along the screw blades 107a, thereby suppressing the diffusion of gas due to suction and / or injection by the gas mixing prevention device 103, and further improving the effect of preventing gas mixing. These devices can also be used in combination with a gate valve device and / or a rotary valve device.

[0051] <Cooling unit> The cooling unit 106 comprises a set of devices required to cool the substrate on which the CNT aggregate has grown. The cooling unit 106 has the function of preventing oxidation and cooling the CNT aggregate, catalyst, and substrate after the growth process in the growth unit 104. The cooling unit 106 shown in FIG. 1 comprises a cooling vessel 106a for holding an inert gas and a water-cooling device 106b arranged to surround the space within the cooling vessel 106a. Note that, regardless of the illustrated embodiment, if the cooling unit is an air-cooled type, the cooling unit may comprise an injection unit or the like that injects inert gas into the space within the cooling vessel. In the illustrated embodiment, the cooling vessel 106a is connected to the growth furnace 104a via a connection unit 110.

[0052] <Connection> As described above, the antechamber 113, the formation furnace 102a, the growth furnace 104a, and the cooling vessel 106a are spatially connected to one another by the connecting parts 108-110. In other words, the connecting parts 108-110 are a set of devices that spatially connect the furnace spaces of each unit and prevent the substrate 111 from being exposed to the outside air when the substrate 111 is transferred from one unit to another. Examples of the connecting parts 108-110 include a furnace or a chamber that isolates the substrate's surrounding environment from the outside air and allows the substrate 111 to pass from one unit to another. For example, the connecting parts 108-110 may be made of Inconel (registered trademark) 601.

[0053] <Outlet purge device> The outlet purge device 105 consists of a set of devices for preventing external air from entering the furnace through the substrate outlet. The outlet purge device 105 has the function of creating a purge gas environment around the substrate 111. Specifically, the outlet purge device 105 can be implemented by a furnace or chamber for maintaining the purge gas environment, an injection unit for injecting the purge gas, etc. The purge gas is preferably an inert gas, and nitrogen is particularly preferred from the standpoints of safety, cost, purgeability, etc. If the substrate outlet is always open, it is preferable to provide a gas curtain device as a purge gas injection unit that injects purge gas from above and below in a shower-like manner to prevent external air from entering through the device outlet.

[0054] <Injection device for reducing gas, raw material gas, and catalyst activation material> The reducing gas injector 102b, the raw material gas injector 104b, and the catalyst activation material injector may each be provided with multiple injection holes. For example, multiple pins may be provided from the wall of the formation furnace and / or growth furnace toward the center of the screw, with multiple injection holes provided on the side and / or tip of each pin. In this case, notches may be provided in the screw blades to avoid interference with the pins. Alternatively, for example, a gas flow path may be formed in the center of the screw shaft of the screw conveyor, with multiple injection holes provided between each blade pitch along the screw shaft direction, or multiple gas nozzles (with multiple injection holes on the side and / or tip) extending from the center of the screw toward each furnace wall surface may be provided. By providing multiple nozzles in the reducing gas injector 102b, the reducing gas can be uniformly dispersed on the substrate, allowing for efficient catalyst reduction. As a result, the uniformity of the CNT aggregate grown on the substrate can be improved, and the consumption of reducing gas can also be reduced. By providing multiple nozzles in the source gas injector 104b, the source gas can be uniformly dispersed onto the substrate, and the source gas can be consumed efficiently. As a result, the uniformity of the aligned CNT aggregate grown on the substrate can be improved, and the consumption of the source gas can also be reduced. By providing multiple nozzles in this way as an injector for the catalytic activator, the catalytic activator can be dispersed evenly over the substrate, which increases the activity of the catalyst and extends its lifespan, enabling the growth of aligned CNTs to continue for a long period of time. This is also true when the catalytic activator is added to the source gas and a showerhead is used as the injector.

[0055] <Materials of equipment parts exposed to reducing gas or raw material gas> Equipment components exposed to reducing gas or raw material gas include the formation unit 102, growth unit 104, transfer unit 107, gas contamination prevention device 103, and some parts of the connection sections 108-110. Materials for these components include those that can withstand high temperatures, such as quartz, heat-resistant ceramics, and heat-resistant alloys. Heat-resistant alloys are preferred in terms of processing accuracy, flexibility, and cost. Examples of heat-resistant alloys include heat-resistant steel, stainless steel, and nickel-based alloys. Materials containing Fe as the main component and 50% or less of other alloys are generally referred to as heat-resistant steel. Steels containing Fe as the main component, 50% or less of other alloys, and approximately 12% or more of Cr are generally referred to as stainless steel. Examples of nickel-based alloys include alloys containing Ni with Mo, Cr, and Fe added. Specifically, SUS310, Inconel 600, Inconel 601, Inconel 625, Incoloy 800, MC alloy, Haynes 230 alloy, etc. are preferred in terms of heat resistance, mechanical strength, chemical stability, low cost, etc.

[0056] When the furnace inner wall and / or parts used in the furnace are made of metal, it is preferable to use a heat-resistant alloy as the material and to subject its surface to hot-dip aluminum plating or polishing so that the arithmetic mean roughness Ra is 2 μm or less.

[0057] Fig. 3 is a diagram for explaining the schematic configuration of an apparatus capable of carrying out a CNT aggregate manufacturing method according to another example of the present invention. Specifically, Fig. 3 explains an embodiment in which a formation unit 202 and a growth unit 204 are separate components and are connected in series by a connection part 208. In Fig. 3, components that are the same as or have similar functions to those in Fig. 1 are indicated by reference numerals that are 100 larger than the reference numerals shown in Fig. 1. Explanation of components that have the same functions will be omitted, and components that differ in terms of arrangement, etc. will be explained below.

[0058] <Connection> The embodiment shown in FIG. 3 differs significantly from the embodiment shown in FIG. 1 in the arrangement of the connecting part 208. Specifically, the connecting part 208 connects the formation unit 202 and the growth unit 204, which are arranged as separate components spaced apart vertically, in series. The connecting part 208 includes a first connecting pipe 208a connected to the downstream side of the formation furnace 202a, a second connecting pipe 208b connected to the upstream side of the growth furnace 204a, and a connecting pipe 208c vertically connecting these pipes. These pipes preferably include a heating device for maintaining the temperature of the substrate 211 inside. As shown in FIG. 3, the first connecting pipe 208a includes a purge gas injector 203b, and the connecting pipe 208c includes an exhaust device 203a. Furthermore, the purge gas injector 203b is provided near the inlet of the growth furnace 204a. These components work together to form the gas mixing prevention device 203.

[0059] 4, the connecting pipe 208c may include a rotary valve device 203c. The rotary valve device 203c includes a rotary valve case 203c-1, a rotary valve 203c-2, and a rotary valve driver 203c-3 that drives the rotary valve case 203c-1, the rotary valve 203c-2, and the rotary valve driver 203c-3 that drives the rotary valve case 203c-1, the rotary valve 203c-2. The movement of the substrate 211 is controlled by the rotation of the rotary valve 203c-2, and by combining this control with the airflow control by the exhaust device 203a and the purge gas injection device 203b, the atmospheres during the formation step and the growth step can be separated more effectively. As a result, the quality of the obtained CNT aggregate and the manufacturing efficiency of the CNT aggregate can be improved.

[0060] <Transport unit> 3 differs from the embodiment shown in FIG. 1 in that the transfer unit is implemented as two separate transfer units. More specifically, the CNT aggregate manufacturing apparatus 200 includes a first transfer unit 207A that transfers the substrate 211 by screw rotation within the furnace space of the formation unit 202, and a second transfer unit 207B that transfers the substrate 211 by screw rotation within the furnace space of the growth unit 204. The first transfer unit 207A includes a first screw blade 207A-a and a first driving device 207A-b. The second transfer unit 207B includes a second screw blade 207B-a and a second driving device 207B-b. Note that, as shown in FIG. 3, the first transfer unit 207A and the second transfer unit 207B may be arranged at an angle to each other rather than being parallel to each other. The angle may be, for example, 10° or less.

[0061] 3, the first driving device 207A-b is disposed downstream of the formation unit 202, and the second driving device 207B-b is disposed upstream of the growth unit 204. This arrangement allows a design in which the connection between the formation unit 202 and the growth unit 204 is fixed, while the ends of the driving devices 207A-b and 207B-b are movably supported on the sides where they are not installed. As a result, even if heated components such as the formation furnace 202a and the growth furnace 204a expand thermally and change in size, the ends of these components are movably supported, thereby reducing the load on the device caused by heat.

[0062] 3, by arranging the formation unit 202 and the growth unit 204 as separate components spaced apart from each other in series by a connection part 208, it is possible to easily optimize the conditions in each of the formation unit 202 and the growth unit 204. This makes it possible to further improve the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate. [Example]

[0063] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples.

[0064] Example 1 A CNT aggregate was manufactured using a CNT aggregate manufacturing apparatus having the general configuration described with reference to FIG. <Catalyst layer formation process> Zirconia (zirconium dioxide) beads (ZrO2, volume average particle diameter D50: 650 μm) as the substrate were placed in a rotary drum coater. While stirring the zirconia beads (20 rpm), an aluminum-containing solution was sprayed with a spray gun (3 g / min, spray time: 940 seconds, spray air pressure: 10 MPa) while supplying compressed air (300 L / min) into the rotary drum to dry, forming an aluminum-containing coating on the zirconia beads. Next, the beads were calcined at 480 °C for 45 minutes to produce primary catalyst particles with an aluminum oxide layer. The primary catalyst particles were then placed in another rotary drum coater and, while stirring (20 rpm), an iron catalyst solution was sprayed with a spray gun (2 g / min, spray time: 480 seconds, spray air pressure: 5 MPa) while supplying compressed air (300 L / min) into the rotary drum to dry, forming an iron-containing coating on the primary catalyst particles. Next, a baking treatment was carried out at 220°C for 20 minutes to prepare a substrate on which an iron oxide layer was further formed.

[0065] The substrate with the catalyst on its surface thus prepared was placed in the feeder hopper of the manufacturing equipment, and while being transported on a screw conveyor, it was processed in the order of formation process, growth process, and cooling process to produce a CNT aggregate.

[0066] <Formation process to cooling process> The conditions for the inlet purge device, formation unit, gas contamination prevention device, growth unit, outlet purge device, and cooling unit of the CNT aggregate manufacturing equipment were set as follows:

[0067] Feeder Hopper Feed rate: 1.25kg / h Displacement: 10sLm (natural exhaust through gaps) Inlet purge device Purge gas: Nitrogen 40sLm Formation Unit ·Furnace temperature: 800℃ Reducing gas: Nitrogen 6sLm, Hydrogen 54sLm Displacement: 60sLm Processing time: 20 minutes Gas contamination prevention device Purge gas: 20sLm Exhaust system displacement: 62sLm Growth Unit ·Furnace temperature: 830℃ Feed gas: Nitrogen 15sLm, Ethylene 5sLm, Carbon dioxide 1sLm, Hydrogen 3sLm Displacement: 47sLm Processing time: 10 minutes Outlet Purge Device Purge gas: Nitrogen 45sLm Cooling unit ·Cooling temperature: room temperature Displacement: 10sLm (natural exhaust through gaps) Continuous production was carried out under the above conditions.

[0068] <Separation and recovery process> The CNT aggregates synthesized on the substrate were separated by a forced vortex separator (rotation speed 2300 rpm, air flow rate 3.5 Nm 3 The recovery rate of CNT aggregates was 96%.

[0069] The properties of the CNT aggregate produced in this example are, as typical values, tap bulk density: 0.02 g / cm 3 , CNT average length: 150 μm, BET-specific surface area: 900 m 2 The carbon purity was 99%. The results of continuous production are shown in Table 1.

[0070] [Table 1]

[0071] Sampling was carried out every hour. Comparing the first and 100th samplings, no decrease in the production volume or deterioration in quality of the CNT aggregates was observed.

[0072] In this way, according to the CNT aggregate apparatus of the present invention, long CNT aggregates with a large specific surface area could be continuously produced with high efficiency without causing a decrease in production volume or deterioration in quality during continuous production.

[0073] Example 2 A CNT aggregate was manufactured using a CNT aggregate manufacturing apparatus having the general configuration described with reference to FIG.

[0074] <Formation process to cooling process> A substrate having a catalyst on its surface, which was produced in the same manner as in Example 1, was placed in the feeder hopper of a CNT aggregate production device, and while being transported by a screw conveyor, it was subjected to the formation process, growth process, and cooling process in that order to produce a CNT aggregate.

[0075] The conditions for the inlet purge device, formation unit, gas mixing prevention device, growth unit, outlet purge section, and cooling unit of the CNT aggregate manufacturing equipment were set as follows:

[0076] Feeder Hopper Feed rate: 2.5kg / h Displacement: 10sLm (natural exhaust through gaps) Inlet purge device Purge gas: Nitrogen 40sLm Formation Unit ·Furnace temperature: 800℃ Reducing gas: Nitrogen 6sLm, Hydrogen 54sLm Total displacement: 90sLm Processing time: 60 minutes Gas contamination prevention device Purge gas: 40sLm Exhaust system displacement: 40sLm Growth Unit ·Furnace temperature: 830℃ Feed gas: Nitrogen 30sLm, Ethylene 10sLm, Carbon dioxide 2sLm, Hydrogen 6sLm Total displacement: 83sLm Processing time: 10 minutes Outlet Purge Device Purge gas: Nitrogen 45sLm Cooling unit ·Cooling temperature: room temperature Displacement: 10sLm (natural exhaust through gaps) Continuous production was carried out under the above conditions.

[0077] <Separation and recovery process> The CNT aggregates synthesized on the substrate were separated by a forced vortex separator (rotation speed 2300 rpm, air flow rate 3.5 Nm 3 The recovery rate of CNT aggregates was 96%.

[0078] The properties of the obtained CNT aggregate were the same as those of Example 1, and no decrease in production volume or deterioration in quality was observed during continuous production.

[0079] Thus, with the device of the present invention, long CNT aggregates with a large specific surface area could be continuously produced with high efficiency without causing a decrease in production volume or deterioration in quality during continuous production.

[0080] Example 3 <Reuse process> 3 kg of the used substrate used in the production of the CNT aggregate in Example 1 was collected and subjected to an oxidation treatment in a rotary kiln furnace (atmosphere: air, temperature: 800°C, treatment time: 30 minutes), and a recycling step was carried out to remove carbon adhering to the surface of the substrate. Using the substrate after the recycling step, each step was carried out in the same manner as in Example 1, and a CNT aggregate was produced.

[0081] The properties of the obtained CNT aggregate were almost the same as those of Example 1, except that the yield was 2.5 mg / g-beads, which was about 80% lower.

[0082] Therefore, it is clear from Example 3 that a long CNT aggregate with a large specific surface area could be produced by reusing the substrate according to the production method of the present invention.

[0083] (Verification example) Using the same catalyst substrate particles and manufacturing equipment as in Example 1, an attempt was made to manufacture a CNT aggregate under the same conditions as in Example 1, except that the conditions of the formation unit, gas contamination prevention device, and growth unit were changed as follows.

[0084] Formation Unit ·Furnace temperature: 800℃ Reducing gas: Nitrogen 6sLm, Hydrogen 54sLm Displacement: 70sLm Processing time: 20 minutes Gas contamination prevention device Purge gas: 0sLm Exhaust system displacement: 0sLm Growth Unit ·Furnace temperature: 830℃ Feed gas: Nitrogen 15sLm, Ethylene 5sLm, Carbon dioxide 1sLm, Hydrogen 3sLm Displacement: 79sLm Processing time: 10 minutes As a result, the surface of the catalyst substrate particles only turned black, and no growth of CNT aggregates was observed.

[0085] This indicates that in the production of CNT aggregates, it is necessary to prevent the raw material gas from being mixed into the reducing gas. [Industrial Applicability]

[0086] According to the present invention, a high-quality CNT aggregate can be efficiently produced. [Explanation of symbols]

[0087] 100,200 CNT aggregate manufacturing equipment 101,201 Inlet purge device 102,202 formation units 102a, 202a Formation Furnace 102b, 202b Reducing gas injection device 102c,202c heating device 102d, 202d exhaust system 103,203 Gas contamination prevention device 103a, 203a Exhaust system 103b, 203b Purge gas injection device 104,204 growth units 104a,204a Growth furnace 104b, 204b Raw material gas injection device 104c,104c',204c heating device 104d, 204d Exhaust system 105,205 Outlet purge device 106,206 Cooling Unit 106a,206a Cooling container 106b,206b Water-cooled chiller 107, 207A, 207B transport unit 107a, 207A-a, 207B-a Screw blades 107b, 207A-b, 207B-b Drive unit 108~110, 208~210 Connection 111,211 Base material 112,212 Hopper 114 Heating device Ex1~Ex3 Raw material gas exhaust port G1, G2 raw gas inlet

Claims

1. A substrate having a specific surface area of ​​600 m ２ A method for producing an aggregate of carbon nanotubes by growing an aggregate of carbon nanotubes of 1 / g or more, a formation unit that realizes a formation step of making the surrounding environment of the catalyst a reducing gas environment and heating at least one of the catalyst and the reducing gas; a growth unit that realizes a growth step of growing the carbon nanotube aggregate by making the surrounding environment of the catalyst a raw material gas environment and heating at least one of the catalyst and the raw material gas; a connection part that spatially connects the furnace space of the formation unit and the furnace space of the growth unit; a first transport unit that transports the substrate in the furnace space of the formation unit by screw rotation, and a second transport unit that transports the substrate in the furnace space of the growth unit by screw rotation, the first transport unit and the second transport unit being configured as one common unit and / or separate units; a gas mixing prevention device that prevents gases from mixing with each other between the furnace space of the formation unit and the furnace space of the growth unit; a manufacturing apparatus in which the formation unit and the growth unit are separate components connected in series by the connection part; The formation step and the growth step are carried out while continuously transporting the substrate and preventing the gas environments in the steps from being mixed with each other. A method for producing an aggregate of carbon nanotubes.

2. 2. The method for producing a carbon nanotube aggregate as described in claim 1, characterized in that the gas mixing prevention device controls the airflow to prevent gases from mixing with each other between the furnace space of the formation unit and the furnace space of the growth unit.

3. In the formation step, the reducing gas is continuously supplied so that the base material transported by the first transport unit and the reducing gas come into contact with each other in a counterflow state in the furnace space of the formation unit; and in the growth step, the source gas is continuously supplied so that the base material transported by the second transport unit and the source gas come into contact with each other in a counterflow state in the furnace space of the growth unit; The method for producing an aggregate of carbon nanotubes according to claim 1 or 2, wherein at least one of the following is carried out.

4. 4. The method for producing an aggregate of carbon nanotubes according to claim 1, wherein the source gas environment in the growing step is a high carbon concentration environment and contains a catalyst activation material.

5. The method for producing an aggregate of carbon nanotubes according to claim 4 , wherein the raw material gas environment contains ethylene and carbon dioxide as the catalyst activation material.

6. The substrate has an apparent density of 2.0 g / cm ３ The method for producing an aggregate of carbon nanotubes according to any one of claims 1 to 5, wherein the particles are the above particles.

7. The method for producing a carbon nanotube aggregate according to claim 6 , wherein the base material contains one or more elements of Al, Si, and Zr.

8. 8. The method for producing a carbon nanotube aggregate according to claim 1, comprising: a catalyst layer forming step of forming a catalyst layer on the substrate; a separation and recovery step of separating the carbon nanotube aggregate from the substrate and separately recovering the substrate and the carbon nanotube aggregate; and a recycling step of making the substrate reusable by oxidizing and removing carbon on the recovered substrate.

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