Method for manufacturing carbon nanotube assemblies

Abstract

The present invention aims to provide a method for manufacturing carbon nanotube assemblies capable of efficiently producing high-quality carbon nanotube assemblies. The present invention is a manufacturing method for growing carbon nanotube assemblies on a substrate having a catalyst on its surface. In this manufacturing method, the substrate is continuously transported by using a transport unit that transports the substrate by screw rotation in each of a formation unit that performs a formation process to reduce the catalyst on the substrate and a growth unit that performs a growth process to grow carbon nanotube assemblies. Furthermore, when carrying out the formation process and the growth process, both processes are carried out while preventing the gas environments in these processes from mixing with each other.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a carbon nanotube assembly, and in particular, a specific surface area of ​​600 m² 2 This invention relates to a manufacturing method for producing high-quality carbon nanotube assemblies with a content of 1 / g or more. Background Technology

[0002] In recent years, nano-carbon materials, such as carbon nanotubes (hereinafter referred to as "CNT"), have attracted attention as materials with excellent conductivity, thermal conductivity, and mechanical properties. Although nano-carbon materials are recognized for their excellent properties, they have generally been more expensive than other materials due to their high manufacturing costs.

[0003] Accordingly, various attempts have been made to efficiently produce nano carbon materials. For example, Patent Document 1 describes a manufacturing method for producing CNTs by ensuring that the respective atmospheres do not mix with each other, including a formation process in which the catalyst is reduced under a reducing gas atmosphere and a growth process in which CNTs are grown on the catalyst under a source gas atmosphere. From the perspective of increasing production efficiency, it is advantageous for the substrate to have a shape with a large surface area per unit volume, such as a powder form; however, when the powder form is conveyed by a belt conveyor, there is a problem that the unevenness of CNT growth between substrates becomes significant because the stirring of the substrate is insufficient. Furthermore, for example, Patent Document 2 describes a method for manufacturing nano carbon, which includes stirring and moving a catalyst body using a conveying means such as a belt conveyor within a reaction tube equipped with a catalyst activation zone, a nano carbon synthesis zone, and a cooling zone. However, since the atmosphere gas of each zone cannot be spatially separated, the process involves temporal switching of the reducing gas and the source gas, or allowing the mixing of each gas, which has not resulted in the substantial continuous production of high-quality nanocarbons such as single-layer carbon nanotubes. Furthermore, for example, Patent Document 3 describes a method for producing nanocarbons that includes continuously supplying a hydrocarbon and a catalyst by a screw feeder so that they come into contact in a counter-current or opposing state. In this study, methane is used as the hydrocarbon of the source gas, and in that case, a catalytic reduction process is not strictly necessary, so there is no need to divide the reaction tube into zones; however, since mainly multilayer carbon nanotubes are synthesized and the growth rate is slow, it has not resulted in the continuous production of high-quality nanocarbons such as single-layer carbon nanotubes with high production efficiency. Prior art literature

[0004] Specification of Japanese Patent No. 5471959, Japanese Published Patent Application No. 2011-241104, Specification of Japanese Patent No. 5285730 The problem to be solved

[0005] Here, the method for manufacturing nano carbon materials according to the prior art had room for improvement in terms of further enhancing the quality and production efficiency of the obtained nano carbon materials.

[0006] Accordingly, the present invention aims to provide a method for manufacturing a carbon nanotube assembly capable of efficiently producing a high-quality carbon nanotube assembly. means of solving the problem

[0007] The inventors conducted a thorough investigation with the aim of solving the above problem. As a result, the inventors newly discovered that it is possible to efficiently produce high-quality CNT assemblies by separately carrying out the formation process and the growth process in this order during the manufacture of CNT assemblies, and by conveying a substrate having a catalyst on its surface by screw rotation during these processes, thereby completing the present invention.

[0008] That is, the present invention aims to advantageously solve the above problem, and the method for manufacturing a CNT aggregate of the present invention comprises a substrate having a catalyst on its surface having a specific surface area of ​​600 m² 2A method for manufacturing a carbon nanotube assembly for growing a carbon nanotube assembly having a carbon nanotube content of 1 / g or more, comprising: a formation unit for realizing a formation process in which the surrounding environment of the catalyst is made into a reducing gas environment while simultaneously heating at least one of the catalyst and the reducing gas; a growth unit for realizing a growth process in which the surrounding environment of the catalyst is made into a source gas environment while simultaneously heating at least one of the catalyst and the source gas to grow the carbon nanotube assembly; a connecting part for spatially connecting the furnace space of the formation unit and the furnace space of the growth unit; a first conveying unit for conveying the substrate by screw rotation in the furnace space of the formation unit; and a second conveying unit for conveying the substrate by screw rotation in the furnace space of the growth unit, wherein the first conveying unit and the second conveying unit are configured as one common unit and / or separate units, the first and second conveying units, and the furnace space of the formation unit and the growth unit The method is characterized by using a manufacturing apparatus having a gas mixing prevention device that prevents gases from mixing with each other within the space inside the furnace, and continuously conveying the substrate while preventing the gas environments in each process from mixing with each other, thereby performing the formation process and the growth process. According to this manufacturing method, high-quality CNT aggregates can be efficiently produced.

[0009] In addition, in the method for manufacturing a CNT aggregate according to the present invention, it is preferable that the formation unit and the growth unit are separate components and are connected in series by the connection unit. According to this manufacturing method, conditions in each of the formation process and the growth process can be easily optimized, thereby further improving the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate.

[0010] In addition, in the method for manufacturing a CNT aggregate according to 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 this manufacturing method, the reduction of the catalyst in the formation process is less likely to be inhibited, thereby further improving the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate.

[0011] Furthermore, in the method for manufacturing a CNT aggregate according to the present invention, it is preferable to implement at least one of the following: in the formation process, the reducing gas is continuously supplied so that the substrate conveyed by the first conveying unit and the reducing gas come into contact with each other in a counter-flow and counter-flow state within the furnace space of the formation unit; and in the growth process, the raw material gas is continuously supplied so that the substrate conveyed by the second conveying unit and the raw material gas come into contact with each other in a counter-flow and counter-flow state within the furnace space of the growth unit. According to such a manufacturing method, the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate can be further improved.

[0012] Furthermore, in the method for manufacturing a CNT aggregate according to the present invention, it is preferable that the source gas environment in the growth process is a high-carbon concentration environment and also includes a catalyst-activating substance. In the growth process, by growing the CNT under a high-concentration carbon environment containing a catalyst-activating substance, the CNT can be grown while maintaining catalytic activity over a long period of time, thereby further improving the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate.

[0013] In addition, in the method for manufacturing a CNT aggregate according to the present invention, it is preferable that the raw gas environment includes ethylene and carbon dioxide as a catalyst activation material. By carrying out the growth process under such an environment, the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate can be further improved.

[0014] And, in the method for manufacturing a CNT aggregate of the present invention, the substrate has an apparent density of 2.0 g / cm³ 3 It is preferable that the particles be of the above type. The substrate has an apparent density of 2.0 g / cm³ 3 If the particles are of the size shown above, the resulting CNT aggregate can be lengthened.

[0015] Meanwhile, the "apparent density" of a support refers to the mass per unit volume including the pores when the support is a particle having internal pores (closed pores). The "apparent density of a support" can be measured by the pycnometer method.

[0016] In addition, in the method for manufacturing a CNT aggregate of the present invention, it is preferable that the substrate comprises one or more elements among Al, Si, and Zr. By using a substrate comprising one or more elements among Al, Si, and Zr, the production efficiency of the CNT aggregate can be further improved.

[0017] In addition, the method for manufacturing a CNT assembly according to the present invention preferably includes a catalyst layer forming process for forming a catalyst layer on the substrate, a separation and recovery process for separating the carbon nanotube assembly from the substrate and recovering the substrate and the carbon nanotube assembly separately, and a reuse process for making the substrate reusable by oxidizing and removing carbon on the recovered substrate. By carrying out such separation and recovery processes and reuse processes, the production efficiency of the CNT assembly can be further improved. Effects of the invention

[0018] According to the present invention, a method for manufacturing a carbon nanotube assembly capable of efficiently producing a high-quality CNT assembly can be provided. Brief explanation of the drawing

[0019] FIG. 1 is a diagram illustrating the schematic configuration of an apparatus capable of carrying out a method for manufacturing a CNT assembly according to an example of the present invention. FIG. 2 is a schematic diagram illustrating the flow of raw material gas in a growth unit equipped in an apparatus capable of carrying out a method for manufacturing a CNT aggregate according to an example of the present invention. FIG. 3 is a diagram illustrating the schematic configuration of an apparatus capable of carrying out a method for manufacturing a CNT assembly according to another example of the present invention. FIG. 4 is a diagram illustrating the schematic configuration of an example of a component of a gas mixing prevention device that can be provided in the device described in FIG. 3. Specific details for implementing the invention

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. According to the method for manufacturing a CNT aggregate of the present invention, the specific surface area is 600 m² 2 Carbon nanotube assemblies with a content of 1 / g or more can be efficiently produced. Meanwhile, in the following description, based on the progression of the process from the formation process to the growth process, an optional cooling process, and the separation process, the preceding operations or components of the manufacturing apparatus performing such operations are described as "front-end" operations or components, and the subsequent operations or components are described as "back-end" operations or components.

[0021] The method for manufacturing a CNT aggregate of the present invention comprises a substrate having a catalyst on its surface and having a specific surface area of ​​600 m² 2This is a manufacturing method for growing CNT aggregates with a content of 1 / g or more. Furthermore, the method for manufacturing a CNT aggregate according to the present invention is a method of performing a formation process and a growth process using a CNT manufacturing apparatus having the following components, while continuously conveying a substrate and preventing the gas environments in each of the following processes from mixing with each other.

[0022] · A formation unit that realizes a formation process in which the surrounding environment of the catalyst becomes a reducing gas environment while simultaneously heating at least one of the catalyst and the reducing gas.

[0023] · A growth unit that realizes a growth process for growing carbon nanotube assemblies by making the surrounding environment of the catalyst a source gas environment and simultaneously heating at least one of the catalyst and the source gas.

[0024] · A connection part that spatially connects the furnace space of the formation unit and the furnace space of the growth unit

[0025] A first conveying unit that conveys a material by screw rotation in the furnace space of a formation unit, and a second conveying unit that conveys a material by screw rotation in the furnace space of a growth unit, wherein the first conveying unit and the second conveying unit are capable of being mounted as one common unit and / or as separate units, the first and second conveying units

[0026] · 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.

[0027] <Substrate having a catalyst on its surface>

[0028] A substrate constituting a substrate having a catalyst on its surface, used in the manufacturing method of the present invention, can be formed by supporting a catalyst on the substrate.

[0029] <<Information>>

[0030] The substrate is a member capable of supporting a catalyst for synthesizing CNTs on its surface, and is not particularly limited; any member made of any material may be used. Among these, it is preferable that the substrate be made of a ceramic material containing one or more elements among Al, Si, and Zr. Furthermore, it is preferable that the substrate be made of a metal oxide containing one or more elements among Al, Si, and Zr, and it is more preferable that it be zirconium dioxide (ZrO2). Also, the shape of the substrate is preferably a particulate form with an aspect ratio of less than 5. Meanwhile, the "aspect ratio" of the substrate particles can be obtained as the average value by calculating the value of (major axis / width orthogonal to the major axis) for a plurality of arbitrarily selected particles on a microscope. Additionally, the substrate particles have an apparent density of 2.0 g / cm³ 3 It is desirable that it be above 3.8 g / cm³ 3 It is desirable that it be above 5.8 g / cm³ 3 It is more desirable to have an ideal value of 8.0 g / cm³ 3The following is preferable. If the apparent density of the particulate substrate is greater than or equal to the above lower limit, the resulting CNT aggregate can be made longer. Furthermore, if the apparent density of the particulate substrate is less than or equal to the above upper limit, the substrate particles have excellent handling properties, which can further increase the production efficiency of the CNT aggregate. Additionally, the particle size of the substrate particles is preferably 0.05 mm or more, more preferably 0.3 mm or more, preferably 10 mm or less, more preferably 2 mm or less, and even more preferably 1 mm or less. If the particle size of the substrate particles is greater than or equal to the above lower limit, the resulting CNT aggregate can be made longer. Additionally, if the particle size of the substrate particles is less than or equal to the above upper limit, the production efficiency of the CNT aggregate can be further increased. Meanwhile, the "particle size" of the substrate particles refers to the volume average particle size D50. The volume average particle size D50 represents the particle size at which the cumulative volume calculated from the small size side in the particle size distribution (volume basis) measured by laser diffraction for the substrate particles is 50%.

[0031] <<Catalyst>>

[0032] The catalyst supported on the substrate is not particularly limited and may include catalyst components such as nickel (Ni), iron (Fe), cobalt (Co), and molybdenum (Mo). Among these, from the perspective of further increasing the production efficiency of the CNT assembly, it is preferable that the catalyst component contains at least one metal of nickel (Ni), iron (Fe), cobalt (Co), and molybdenum (Mo).

[0033] Additionally, optionally, as a base for supporting a catalyst on the substrate, a lower layer formed of a material such as aluminum oxide, titanium oxide, titanium nitride, or silicon oxide can be formed.

[0034] <<Method for preparing a substrate having a catalyst on its surface>>

[0035] The method for supporting a catalyst (or catalyst layer) on the surface of a substrate (catalyst layer formation process) is not particularly limited, and any existing method may be adopted. Among these, when substrate particles are used as the substrate, a method using a rotary drum type coating device equipped with a roughly cylindrical rotary drum is preferred. This method includes a spraying process in which a substrate is placed inside a roughly cylindrical rotary drum and the rotary drum is rotated with an inclined axis as the rotation axis to agitate the substrate particles while spraying a catalyst solution containing the aforementioned catalyst component onto the agitated substrate particles, and a drying process in which a drying gas is introduced into the rotary drum to contact the substrate particles sprayed with the catalyst solution with the drying gas, wherein at least a portion of the duration of the agitation process and at least a portion of the duration of the spraying process overlap. When a catalyst is supported after a lower layer is placed on the surface of a substrate, a substrate particle having a lower layer on its surface can be obtained by performing the same spraying and drying processes as above using a solution containing a component capable of constituting the lower layer and substrate particles prior to spraying and drying the catalyst solution. In addition, by providing the substrate particles having a lower layer on their surface to the spraying and drying processes described above, a substrate particle can be obtained in which the lower layer and the catalyst (or catalyst layer) are supported on the surface in this order.

[0036] Meanwhile, in addition to the above, a method for preparing a substrate having a catalyst (or catalyst layer) on its surface when substrate particles are used as the substrate may include, for example, a process of spraying a catalyst solution while causing the substrate particles to flow in a centrifugal swirling flow and a vertical floating flow.

[0037] <Reducing Gas>

[0038] A reducing gas is a gas that has at least one of the effects of reducing the catalyst, promoting the atomization of the catalyst, and enhancing the activity of the catalyst. Examples of reducing gases that may be used include hydrogen gas, ammonia, water vapor, and mixtures thereof. Additionally, as a reducing gas, a mixture of hydrogen gas and an inert gas such as helium, argon, or nitrogen may be used. The reducing gas is generally used in the formation process, but it may also be used in the growth process to a suitable degree.

[0039] <Fuel Gas>

[0040] Examples of raw materials used for the synthesis of CNT assemblies include hydrocarbons such as methane, ethane, ethylene, propane, butane, pentane, hexane, heptanepropylene, and acetylene; lower alcohols such as methanol and ethanol; and oxygen-containing compounds with a low carbon number such as acetone and carbon monoxide. In addition, a mixture of multiple types may be used. Furthermore, the raw materials may also be diluted with an inert gas as described above.

[0041] Here, it is preferable that the raw material gas contains ethylene. By heating ethylene within a predetermined temperature range (700°C or higher and 900°C or lower), the decomposition reaction of ethylene is promoted, and when the decomposition gas comes into contact with the catalyst, high-speed growth of CNTs becomes possible. However, if the thermal decomposition time is excessively long, the decomposition reaction of ethylene proceeds excessively, causing deactivation of the catalyst or attachment of carbon impurities to the CNT aggregate. In the method for manufacturing a CNT aggregate according to the present invention, for an ethylene concentration in the range of 0.1 volume% or higher and 40 volume% or lower, a thermal decomposition time in the range of 0.5 seconds or higher and 10 seconds or lower is preferred. If the time is less than 0.5 seconds, the thermal decomposition of ethylene is insufficient, making it difficult to grow CNT aggregates with a high specific surface area at high speed. If the time is longer than 10 seconds, the decomposition of ethylene proceeds excessively, generating a large amount of carbon impurities, which leads to catalyst deactivation or deterioration of the quality of the CNT aggregate. The thermal decomposition time can be calculated from the following equation.

[0042] (Thermal decomposition time) = (Heating channel volume) / {(Raw gas flow rate) × (273.15 + T) / 273.15}

[0043] Here, the heated flow path volume is the volume of the flow path heated to a predetermined temperature T°C through which the source gas passes before coming into contact with the catalyst, and the source gas flow rate is the flow rate at 0°C and 1 atm.

[0044] Catalytic Revitalization Substance

[0045] In the CNT growth process, a catalyst revitalizing agent may be added. By adding a catalyst revitalizing agent, the production efficiency and quality of the CNT aggregate can be further improved. The catalyst revitalizing agent used here is generally a substance containing oxygen that does not cause significant damage to the CNT at the growth temperature. In addition to water, examples include hydrogen sulfide; oxygen-containing compounds with a low carbon-to-water ratio such as oxygen, ozone, nitrogen oxide, carbon monoxide, and carbon dioxide; alcohols such as ethanol and methanol; ethers such as tetrahydrofuran; ketones such as acetone; aldehydes; esters; nitrogen oxides; and mixtures thereof. Among these, water, oxygen, carbon dioxide, carbon monoxide, or tetrahydrofuran are preferred, and carbon dioxide is more preferred. In the growth process, by growing the CNT under a high-concentration carbon environment containing the catalyst revitalizing agent, the CNT can be grown while maintaining catalytic activity over a long period of time, thereby further improving the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate. In addition, when the raw gas contains ethylene, if carbon dioxide is present as a catalyst activating agent, the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate can be further improved. The reason for this is presumed to be as follows. First, in the CNT synthesis reaction, it has been found that ethylene is relatively low-activity as a carbon source and carbon dioxide is relatively low-activity as a catalyst activating agent. Therefore, when a gas mixture containing each of the above gases passes through a layer made of substrates having a catalyst on their surface—that is, a layer made of an aggregate of substrates continuously conveyed by screw rotation—the decrease in the concentration of each gas due to the CNT synthesis reaction is very gradual, and the concentration distribution of each gas within the layer can be relatively uniform. As a result, CNT growth between substrates also becomes uniform, making it possible to increase production efficiency.

[0046] The amount of catalyst activation material added in the growth process, for example, if it is carbon dioxide, is 0.5 volume% or more of the atmosphere in the growth process, preferably 4 volume% or more, more preferably 5 volume% or more, and typically 40 volume% or less.

[0047] High Carbon Concentration Environment

[0048] A high carbon concentration environment refers to an atmosphere in which 0.1 volume% or more of the atmosphere in the growth process (hereinafter also referred to as the "raw material gas environment") is raw material gas. Meanwhile, the proportion of raw material gas in the high carbon concentration environment may be, for example, 40 volume% or less. Furthermore, the proportion of raw material gas in the high carbon concentration environment is preferably 4 volume% or more, more preferably 5 volume% or more, even more preferably 10 volume% or more, and preferably 30 volume% or less. Here, by including a catalyst-activating substance in the raw material gas environment, the catalyst activity is significantly improved, so even under a high carbon concentration environment, the catalyst does not lose its activity, making it possible to grow CNT aggregates over a long period of time, and at the same time, the growth rate can also be significantly improved.

[0049] <Reaction Temperature>

[0050] The reaction temperature for growing the CNT aggregate is not particularly limited and, for example, may be 400°C or higher and 1100°C or lower. In addition, if the source gas contains ethylene, it is preferable that the temperature be 700°C or higher and 900°C or lower.

[0051] Formation Process

[0052] A formation process is a process in which the surrounding environment of a catalyst supported on a substrate is made into a reducing gas environment, while simultaneously heating at least one of the catalyst and the reducing gas. Through this process, at least one of the following effects is produced: reduction of the catalyst, promotion of micronization into a state suitable for the growth of CNTs of the catalyst, and enhancement of the catalyst's activity.

[0053] In the formation process, it is desirable to continuously supply the reducing gas so that the substrate and the reducing gas, which are conveyed by the first conveying unit, come into contact with each other in counter-flow and counter-flow states within the furnace space of the formation unit. According to this manufacturing method, the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate can be further improved. More specifically, by bringing the substrate and the reducing gas conveyed by the first conveying unit into contact with each other in counter-flow and counter-flow states, the contact time between the two can be efficiently ensured because the substrate and the reducing gas can be in contact over the period during which the substrate is conveyed within the formation unit. Furthermore, by configuring the system so that both counter-flow and counter-flow are realized as the direction of contact, rather than selecting only one of them, the contact efficiency between the two can also be increased. In addition, in this configuration, by appropriately positioning the introduction and exhaust locations of the reducing gas, it becomes possible to optimize the residence time of the reducing gas within the manufacturing apparatus. By doing so, the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate can be further improved.

[0054] The temperature of the catalyst support or the reducing gas atmosphere in the formation process is preferably 400°C or higher and 1100°C or lower. In addition, the execution time of the formation process may be 3 minutes or more and 120 minutes or lower.

[0055] Growth Process

[0056] The growth process is a process for growing CNT aggregates by heating at least one of the catalyst and the raw gas, while simultaneously making the surrounding environment of the catalyst, which has become suitable for manufacturing CNT aggregates by the formation process described above, into a raw gas environment. Furthermore, the manufacturing method of the present invention is characterized by carrying out both processes while continuously conveying the substrate by screw rotation, while preventing the gas environments in the formation process and the growth process from mixing with each other. By doing so, the quality of the obtained CNT aggregates and the production efficiency of the CNT aggregates can be further improved.

[0057] In the growth process as well, similar to the formation process described above, it is desirable to continuously supply the raw material gas so that the substrate and the raw material gas, which are conveyed by the second conveying unit within the furnace space of the growth unit, come into contact with each other in a counter-flow and counter-flow state. By doing so, the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate can be further improved. In addition, by appropriately arranging the introduction and exhaust locations of the raw material gas, it becomes possible to optimize the residence time of the raw material gas within the manufacturing apparatus. By doing so, the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate can also be further improved.

[0058] <Cooling Process>

[0059] Optionally, a cooling process may be performed after the growth process. In the cooling process, the CNT aggregate, catalyst, and substrate obtained from the growth process are cooled under an inert gas environment. Since the CNT aggregate, catalyst, and substrate after the growth process are in a high-temperature state, they tend to be easily oxidized when placed in an environment where oxygen is present. Therefore, it is desirable to cool the CNT oriented aggregate, catalyst, and substrate to 400°C or lower, more preferably 200°C or lower, under an inert gas environment.

[0060] Separation and Recovery Process

[0061] In the separation and recovery process, carbon nanotube assemblies are separated from the substrate, and the substrate and carbon nanotube assemblies are recovered separately. The recovery method is not particularly limited, and any known method may be employed. Among these, it is preferable to employ a separation and recovery method utilizing an external force and a fluid flow acting as the drag force of that external force (e.g., an air vortex formed by centrifugal force and an airflow acting as the drag force of that centrifugal force) (e.g., see International Publication No. 2019 / 188979).

[0062] Reuse Process

[0063] In the reuse process, the substrate is made reusable by oxidizing and removing carbon from the recovered substrate. The method for oxidizing and removing carbon is not particularly limited; for example, a method of heating the substrate while circulating air may be used. By implementing this reuse process, costs related to the substrate can be reduced.

[0064] <CNT 집합체의 속성>

[0065] The specific surface area of ​​the CNT aggregate obtained by the manufacturing method of the present invention is a value obtained by measuring the adsorption-desorption isotherm at 77 K in liquid nitrogen for CNTs that have not undergone aperture treatment, and then measuring the value from this adsorption-desorption isotherm curve using the method of Brunauer, Emmett, and Teller. 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 m² 2 / g or more, and 800 m 2 It is desirable to be greater than / g, and 2600 m 2 It is desirable that it be / g or less, and 1400 m 2 It is more preferable that it is / g or less. In addition, for the aperture-treated CNT aggregate, the specific surface area is 1300 m² 2It is desirable that it be greater than / g.

[0066] (CNT manufacturing device)

[0067] FIG. 1 is a diagram illustrating the schematic configuration of an apparatus capable of implementing a method for manufacturing a CNT assembly according to an example of the present invention. According to the CNT assembly manufacturing apparatus (100) shown in FIG. 1, the method for manufacturing a CNT assembly according to the present invention can be implemented. Such a CNT assembly manufacturing apparatus (100) comprises a formation unit (102), a growth unit (104), a conveying unit (107) that conveys a substrate while it passes from the formation unit (102) to the growth unit (104), a connecting part (108) that spatially connects the formation unit (102) and the growth unit (104) to each other, and a gas mixing prevention device that prevents gas from mixing between the formation unit (102) and the growth unit (104). Additionally, the CNT assembly manufacturing device (100) is equipped with components such as an inlet purge device (101) positioned at the front end of a formation unit (102), an outlet purge device (105) positioned at the rear end of a growth unit (104), and furthermore, a cooling unit (106) positioned at the rear end of the outlet purge device (105).

[0068] Inlet Purge Device

[0069] The inlet purge device (101) consists of a set of devices designed to prevent external air from being mixed into the device furnace from the substrate inlet. It has the function of replacing the surrounding environment of the substrate conveyed into the CNT assembly manufacturing device (100) with purge gas. Examples include a furnace or chamber for maintaining the purge gas, and a spray device for spraying the purge gas. The purge gas is preferably an inert gas, and is particularly preferably nitrogen in terms of safety, cost, and purgeability. It may contain a small amount of hydrogen for the purpose of improving catalytic activity. When the substrate inlet is always open, the purge gas spray device is preferably configured as a gas curtain device consisting of an air supply device configured to spray the purge gas from above and below in a shower-like manner, thereby preventing external air from being mixed in from the inlet of the CNT assembly manufacturing device (100). In the embodiment shown in FIG. 1, the inlet purge device (101) is mounted on a connecting part (109) that connects a front chamber (113), which is a component that introduces material into the system through a hopper (112), and a formation furnace (102a).

[0070] <Formation Unit>

[0071] The formation unit (102) consists of a set of devices for realizing a formation process. The formation unit (102) has the function of making the surrounding environment of the catalyst formed on the surface of the substrate into a reducing gas environment, while simultaneously heating at least one of the catalyst and the reducing gas. The formation unit (102) may be composed of, for example, a formation furnace (102a) for maintaining 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 inside 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 heating heater, an infrared heating heater, an electromagnetic induction heater, etc. Additionally, the heating device (102c) may heat the system so that the temperature inside the formation furnace becomes 400°C or higher and 1100°C or lower. Additionally, the exhaust device (102d) is a component for exhausting the reducing gas inside the furnace, comprising a reducing gas exhaust port positioned 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.

[0072] Growth Unit

[0073] The growth unit (104) consists of a set of devices for realizing a growth process. The growth unit (104) has the function of growing a CNT assembly by heating at least one of the catalyst and the raw gas while simultaneously making the surrounding environment of the catalyst, which has become suitable for manufacturing a CNT assembly by a formation process, into a raw gas environment. Specifically, the growth unit (104) may be composed of a growth furnace (104a) for maintaining a raw gas environment, a raw gas injection device (104b) for injecting raw gas, a heating device (104c) for heating at least one of the catalyst and the raw gas, and an exhaust device (104d) for discharging gas inside the furnace to the outside. The heating device (104c) is not particularly limited and may be implemented, for example, by a resistance heating heater, an infrared heating heater, an electromagnetic induction heater, etc. Additionally, although not illustrated, it is preferable that the growth unit (104) be equipped with a catalyst activation material addition device. Additionally, the exhaust device (104d) is a component for exhausting raw material gas inside the furnace to the outside, comprising a raw material gas exhaust port positioned on the side of the furnace body of the growth furnace (104a). The growth unit (104) preferably has at least one raw material gas exhaust port, and may have multiple ports.

[0074] Here, with reference to FIG. 2, the flow of raw material gas in the growth unit is explained. Meanwhile, for clarity, the illustration of the conveying unit is omitted in FIG. 2. For each component that performs the same function as each component shown in FIG. 1, the same reference numeral used in FIG. 1 is attached. For components that perform basically the same function as each component shown in FIG. 1 but differ slightly in arrangement, etc., the same reference numeral used in FIG. 1 is attached to the reference numeral used in FIG. 1. The growth furnace (104a) shown in FIG. 2 is equipped with a plurality of heating devices (104c'), and has two raw material gas inlets (G1 and G2) on the side of the furnace body, and a total of three raw material gas exhaust ports (Ex1 to Ex3), one in the gap between them and one each on the front and rear sides in the direction of conveying the material. The two raw material gas inlets (G1 and G2) flow in the forward and reverse directions relative to the substrate conveying direction according to the suction force originating from the exhaust from the raw material gas exhaust ports (Ex1 to Ex3). As a result, the substrate conveyed along the conveying direction and the raw material gas come into contact with each other in the state of counter-flow and counter-flow. In addition, 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 in the raw material gas exhaust ports (Ex1 to Ex3) in various ways, it becomes possible to easily optimize the residence time of the raw material gas within the system. As a result, the quality of the obtained CNT aggregate and the production efficiency of the CNT aggregate can be further improved. Furthermore, forming such a gas flow makes it possible to realize the function of preventing mutual mixing of gases within the furnace space between adjacent units by controlling the airflow of the gas mixing prevention device (103).

[0075] Meanwhile, although a growth unit has been described as a specific example in this description, by applying the same configuration to a formation unit, the same control can be easily realized for the behavior of the reducing gas within the formation unit.

[0076] <Catalyst Revitalization Material Addition Device>

[0077] The catalyst revitalization material addition device consists of a set of devices for adding the catalyst revitalization material into the raw gas or directly adding the catalyst revitalization material to the surrounding environment of the catalyst within the growth furnace. The catalyst revitalization material addition device may include a supply system capable of supplying the catalyst revitalization material, although not specifically limited, for example, supplying via a bubbler, supplying a vaporized solution containing the catalyst revitalizer, supplying as a gas, and supplying a liquefied or vaporized solid catalyst revitalizer. Such a supply system may include, for example, a vaporizer, a mixer, an agitator, a diluent, a sprayer, a pump, and a compressor. Furthermore, a device for measuring the concentration of the catalyst revitalization material may be installed in the supply pipe of the catalyst revitalization material. By using this output value for feedback control, a stable supply of the catalyst revitalization material with minimal variation over time can be achieved.

[0078] <Return Unit>

[0079] The conveying unit (107) is a unit that continuously conveys a substrate (111) by rotating a screw. For example, the conveying unit (107) may be implemented by a screw conveyor. The screw conveyor may be implemented by a screw blade (107a) and a driving device (107b), such as a motor, which can rotate the screw blade to enable the conveying of the substrate. Meanwhile, as shown in FIG. 1, the substrate may be introduced into the device from outside the system, for example, through a hopper (112). In addition, the area near the driving device (107b) may be heated by a heating device (114) configured to heat the inside of the system at a temperature lower than the heating temperature in the formation unit. The diameter of the screw blade constituting the screw conveyor and the winding pitch, etc., can be arbitrarily adjusted according to the size of the substrate used.

[0080] Here, in FIG. 1, a configuration is illustrated in which a first conveying unit that conveys a material by screw rotation in the furnace space of a formation unit (102) and a second conveying unit that conveys a material by screw rotation in the furnace space of a growth unit (104) are implemented by a screw blade (107a) and a driving device (107b), which are a single common unit. As described below with reference to FIG. 3, the first conveying unit and the second conveying unit can also be implemented as separate units. Alternatively, there may be two individual conveying units, with the first conveying unit being the first conveying unit and the second conveying unit being a single unit that is common to both the first and second.

[0081] Gas Ingress Prevention Device

[0082] The gas mixing prevention device (103) is installed in a connection part (108) that spatially connects the formation unit (102) and the growth unit (104) to each other, and is composed of a set of devices to realize the function of preventing gas from mixing into the furnace space of the formation unit (102) and the growth unit (104). The gas mixing prevention device (103) is not particularly limited and may be implemented by a gas curtain device composed of a gate valve device or a rotary valve device capable of mechanically blocking the spatial connection of each unit at times other than during movement from unit to unit of the substrate, an air supply device configured to inject purge gas, and an exhaust device that discharges gas present inside 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. Among these, 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 assembly manufacturing device (100). In addition, it is preferable that the gas mixing prevention device (103) has a purge gas injection device (103b) that injects purge gas (sealing gas) along the opening of the connection part (108) in addition to the exhaust device (103a), and that the exhaust device (103a) sucks in the purge gas and exhausts it to the outside of the manufacturing device. With the CNT assembly manufacturing device (100) having such a configuration, it is difficult to inhibit the reduction of the catalyst in the formation process, and thus the quality of the obtained CNT assembly and the production efficiency of the CNT assembly can be further improved.In addition, the screw conveyor, which is a return unit (107), can further enhance the gas mixing prevention effect by rectifying the flow of gas within the furnace space into a flow along the screw blade (107a), thereby suppressing the diffusion of gas caused by suction and / or injection by the gas mixing prevention device (103). Meanwhile, these may be used in combination with a gate valve device and / or a rotary valve device.

[0083] Cooling Unit

[0084] The cooling unit (106) consists of a set of devices necessary for cooling a substrate on which a CNT aggregate has been grown. The cooling unit (106) has the function of preventing oxidation and cooling of the CNT aggregate, catalyst, and substrate after the growth process in the growth unit (104). The cooling unit (106) shown in FIG. 1 is equipped with a cooling vessel (106a) for maintaining an inert gas and a water cooling device (106b) arranged to surround the space inside the cooling vessel (106a). Meanwhile, regardless of the illustrated embodiment, if the cooling unit is air-cooled, the cooling unit may be equipped with a spraying unit that sprays an inert gas into the space inside the cooling vessel. In the illustrated embodiment, the cooling vessel (106a) is connected to the growth furnace (104a) through a connecting unit (110).

[0085] <Connection Section>

[0086] As described above, the anteroom (113), the formation furnace (102a), the growth furnace (104a), and the cooling vessel (106a) are each spatially connected to one another by connecting parts (108 to 110). In other words, the connecting parts (108 to 110) are a set of devices for spatially connecting the furnace space of each unit to prevent the substrate (111) from being exposed to the outside air when the substrate (111) is transported from unit to unit. Examples of connecting parts (108 to 110) include furnaces or chambers that block the environment surrounding the substrate and the outside air and allow the substrate (111) to pass from unit to unit. For example, the material of the connecting parts (108 to 110) may be Inconel (registered trademark) 601.

[0087] Exit Purge Device

[0088] The outlet purge device (105) consists of a set of devices designed to prevent external air from being mixed into the device furnace from the substrate outlet. The outlet purge device (105) has the function of making the surrounding environment of the substrate (111) into a purge gas environment. Specifically, the outlet purge device (105) may be implemented in a furnace or chamber for maintaining the purge gas environment, a spraying unit for spraying purge gas, etc. The purge gas is preferably an inert gas, and is particularly preferably nitrogen in terms of safety, cost, and purgeability. When the substrate outlet is always open, it is preferable to install a gas curtain device that sprays purge gas from above and below in a shower-like manner as a purge gas spraying unit to prevent external air from being mixed in from the device outlet.

[0089] Injection device for reducing gas, source gas, and catalyst revitalization material

[0090] A plurality of discharge holes may be provided as a reduction gas injection device (102b), a raw material gas injection device (104b), and a catalyst revitalization material injection device. For example, a plurality of pins may be installed from the wall of the formation furnace and / or growth furnace toward the center of the screw, and a plurality of discharge holes may be provided on the side and / or tip of each pin. In that case, a cutout is formed on the screw blade to avoid interference with each pin. Additionally, for example, a gas flow path may be formed at the center of the screw axis of the screw conveyor, and a plurality of discharge holes may be formed between each blade pitch along the screw axis direction, or a plurality of gas nozzles (with a plurality of discharge holes on the side and / or tip) extending from the center of the screw toward each furnace wall may be provided.

[0091] By forming multiple ejection holes in this manner as a reducing gas injection device (102b), the reducing gas can be uniformly dispersed onto the substrate, thereby allowing the catalyst to be reduced efficiently. As a result, the uniformity of the CNT aggregate growing on the substrate can be increased, and the consumption of reducing gas can also be reduced.

[0092] By forming a plurality of ejection holes in this manner as a raw material gas injection device (104b), the raw material gas can be uniformly dispersed on the substrate, allowing the raw material gas to be consumed efficiently. As a result, the uniformity of the CNT orientation aggregate growing on the substrate can be increased, and the amount of raw material gas consumed can also be reduced.

[0093] By forming multiple ejection holes in this manner as an injection device for the catalyst revitalization material, the catalyst revitalization material can be uniformly dispersed onto the substrate. This increases the activity of the catalyst and extends its lifespan, thereby enabling the continuous growth of oriented CNTs for an extended period. The same applies when the catalyst revitalization material is added to the source gas and a shower head is used as the injection device.

[0094] <Material of device parts exposed to reducing gas or source gas>

[0095] The device parts exposed to the reducing gas or raw gas include the formation unit (102), the growth unit (104), the conveying unit (107), the gas mixing prevention device (103), and parts of the connection parts (108 to 110). The materials constituting each of these components may be materials capable of withstanding high temperatures, such as quartz, heat-resistant ceramics, and heat-resistant alloys, but heat-resistant alloys are preferred in terms of processing precision, freedom of movement, and cost. Examples of heat-resistant alloys include heat-resistant steel, stainless steel, and nickel-based alloys. A material with Fe as the main component and other alloy concentrations of 50% or less is generally called heat-resistant steel. Additionally, a steel with Fe as the main component, other alloy concentrations of 50% or less, and containing about 12% or more of Cr is generally called stainless steel. Furthermore, nickel-based alloys may include alloys in which Mo, Cr, and Fe are added to Ni. Specifically, SUS310, Inconel 600, Inconel 601, Inconel 625, Incoloy 800, MC Alloy, Haynes 230 Alloy, etc. are desirable in terms of heat resistance, mechanical strength, chemical stability, and low cost.

[0096] Meanwhile, when the inner wall of the furnace and / or parts used inside the furnace are made of metal, it is preferable to use a heat-resistant alloy for the material and to also treat the surface with molten aluminum plating or to polish the surface so that the arithmetic mean roughness Ra ≤ 2μm.

[0097] FIG. 3 is a diagram illustrating the schematic configuration of an apparatus capable of implementing a method for manufacturing a CNT assembly according to another example of the present invention. Specifically, FIG. 3 illustrates an embodiment in which a formation unit (202) and a growth unit (204) are separate components and are connected in series by a connecting unit (208). In FIG. 3, for components that are identical to or perform the same function as FIG. 1, a value obtained by adding 100 to the reference numeral shown in FIG. 1 is used as the reference numeral. Description of components having the same function is omitted, and components that differ in terms of arrangement, etc., will be described below.

[0098] <Connection Section>

[0099] In the embodiment shown in FIG. 3, the arrangement of the connecting section (208) differs significantly from the embodiment shown in FIG. 1. Specifically, the connecting section (208) connects a formation unit (202) and a growth unit (204), which are arranged as separate components separated vertically, in series. The connecting section (208) is equipped with a first connecting pipe (208a) connected to the rear end of the formation furnace (202a), a second connecting pipe (208b) connected to the front end of the growth furnace (204a), and a connecting pipe (208c) connecting the two in a vertical direction. Meanwhile, it is preferable that these pipes be equipped with a heating device to keep the internal substrate (211) warm. As shown in FIG. 3, the first connecting pipe (208a) is equipped with a purge gas injection device (203b), and the connecting pipe (208c) is equipped with an exhaust device (203a). Additionally, a purge gas injection device (203b) is installed near the inlet of the growth furnace (204a). These components work together to form a gas mixing prevention device (203).

[0100] Here, as shown in FIG. 4, the connecting pipe (208c) may be equipped with a rotary valve device (203c). The rotary valve device (203c) is equipped with a rotary valve case (203c-1), a rotary valve (203c-2), and a rotary valve driver (203c-3) that drives it. By rotating the rotary valve (203c-2), the movement of the substrate (211) is controlled, and by combining this control with the control of the airflow by the exhaust device (203a) and the purge gas injection device (203b), the atmosphere between the formation process and the growth process can be separated even more effectively. As a result, the quality of the obtained CNT aggregate and the manufacturing efficiency of the CNT aggregate can be increased.

[0101] <Return Unit>

[0102] Additionally, the embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 1 in that the conveying unit is implemented as two separate conveying units. More specifically, the CNT assembly manufacturing apparatus (200) comprises a first conveying unit (207A) that conveys a substrate (211) by screw rotation in the furnace space of a formation unit (202), and a second conveying unit (207B) that conveys a substrate (211) by screw rotation in the furnace space of a growth unit (204). The first conveying unit (207A) comprises a first screw blade (207A-a) and a first driving device (207A-b). The second conveying unit (207B) comprises a second screw blade (207B-a) and a second driving device (207B-b). Meanwhile, as shown in FIG. 3, the first conveying unit (207A) and the second conveying unit (207B) may be arranged at an angle rather than parallel to each other. Such an angle may be, for example, 10° or less.

[0103] Here, in the embodiment shown in FIG. 3, a first driving device (207A-b) is positioned on the rear side of the formation unit (202), and a second driving device (207B-b) is positioned on the front side of the growth unit (204). By adopting this arrangement, it is possible to design the connection between the formation unit (202) and the growth unit (204) so ​​that each end of the side where each driving device (207A-b and 207B-b) is not installed remains movable. As a result, even if the heated components such as the formation furnace (202a) and the growth furnace (204a) undergo thermal expansion and change in size, each end of these components remains movable, thereby suppressing the device load caused by heat.

[0104] In addition, as shown in the embodiment of FIG. 3, by arranging the formation unit (202) and the growth unit (204) as separate components separated vertically and connected in series by a connecting part (208), the conditions of each of the formation unit (202) and the growth unit (204) can be easily optimized. By doing so, the quality of the obtained CNT aggregate and the manufacturing efficiency of the CNT aggregate can be further improved.

[0105] Examples

[0106] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0107] (Example 1)

[0108] A CNT assembly was manufactured using a CNT assembly manufacturing apparatus that satisfies the schematic configuration described with reference to Fig. 1.

[0109] <Catalyst layer formation process>

[0110] Zirconia (zirconium dioxide) beads (ZrO2, volume average particle size D50: 650 μm) as a substrate were fed into a rotary drum type coating device, and while stirring the zirconia beads (20 rpm), an aluminum-containing solution was sprayed by a spray gun (spray amount 3 g / min, spray time 940 seconds, spray air pressure 10 MPa), and compressed air (300 L / min) was supplied into the rotary drum to dry the zirconia beads, thereby forming an aluminum-containing coating film on the zirconia beads. Next, a calcination treatment was performed at 480°C for 45 minutes to produce primary catalyst particles with an aluminum oxide layer formed thereon. In addition, the primary catalyst particles were fed into another rotary drum type coating device and stirred (20 rpm), while spraying the iron catalyst solution with a spray gun (spray amount 2 g / min, spray time 480 seconds, spray air pressure 5 MPa), and drying was performed while supplying compressed air (300 L / min) into the rotary drum to form an iron-containing coating film on the primary catalyst particles. Next, a firing treatment was performed at 220°C for 20 minutes to produce a substrate with an iron oxide layer further formed.

[0111] A substrate having a catalyst on its surface, prepared in this manner, was fed into the feeder hopper of a manufacturing apparatus and, while being conveyed by a screw conveyor, processed in the order of a formation process, a growth process, and a cooling process to produce a CNT aggregate.

[0112] <Formation Process ~ Cooling Process>

[0113] The conditions for each of the inlet purge device, formation unit, gas ingress prevention device, growth unit, outlet purge device, and cooling unit of the CNT assembly manufacturing device were set as follows.

[0114] feeder hopper

[0115] · Feed rate: 1.25 kg / h

[0116] · Displacement: 10 sLm (natural exhaust from gap)

[0117] Inlet purge device

[0118] · Purge gas: Nitrogen 40 sLm

[0119] Formation Unit

[0120] · Furnace internal temperature: 800℃

[0121] · Reducing gas: Nitrogen 6 sLm, Hydrogen 54 sLm

[0122] · Displacement: 60 sLm

[0123] · Processing time: 20 minutes

[0124] Gas mixing prevention device

[0125] · Purge gas: 20 sLm

[0126] · Exhaust displacement: 62 sLm

[0127] Growth Unit

[0128] · Furnace internal temperature: 830℃

[0129] · Source gas: Nitrogen 15 sLm, Ethylene 5 sLm, Carbon dioxide 1 sLm, Hydrogen 3 sLm

[0130] · Displacement: 47 sLm

[0131] · Processing time: 10 minutes

[0132] Exit purge device

[0133] · Purge gas: Nitrogen 45 sLm

[0134] cooling unit

[0135] · Cooling temperature: Room temperature

[0136] · Displacement: 10 sLm (natural exhaust from gap)

[0137] Continuous manufacturing was carried out under the above conditions.

[0138] Separation and Recovery Process

[0139] The CNT aggregate synthesized on the substrate is subjected to a forced vortex classifier (rotation speed 2300 rpm, air flow rate 3.5 Nm 3Separation and recovery were performed using (min). The recovery rate of the CNT aggregate was 96%.

[0140] The characteristics of the CNT aggregate produced according to the present embodiment are, as a typical value, tab apparent density: 0.02 g / cm³ 3 , CNT average length: 150μm, BET specific surface area: 900 m 2 / g, average outer diameter: 4.0 nm, carbon purity 99%. The results of continuous manufacturing are shown in Table 1.

[0141]

[0142] Sampling was performed at 1-hour intervals. Even when comparing the 1st and 100th samples, no decrease in the production quantity or deterioration in quality of the CNT aggregates was observed.

[0143] Thus, according to the CNT aggregate manufacturing apparatus of the present invention, long-length CNT aggregates with a high specific surface area could be continuously manufactured with high efficiency without causing a decrease in production volume or quality deterioration during continuous manufacturing.

[0144] (Example 2)

[0145] A CNT assembly was manufactured using a CNT assembly manufacturing apparatus that satisfies the schematic configuration described with reference to Fig. 3.

[0146] <Formation Process ~ Cooling Process>

[0147] A substrate having a catalyst on its surface, prepared in the same manner as in Example 1, was fed into the feeder hopper of a CNT assembly manufacturing apparatus and, while being conveyed by a screw conveyor, processed in the order of a formation process, a growth process, and a cooling process to manufacture a CNT assembly.

[0148] The conditions of the inlet purge device, formation unit, gas ingress prevention device, growth unit, outlet purge section, and cooling unit of the CNT assembly manufacturing device were set as follows.

[0149] feeder hopper

[0150] · Feed rate: 2.5 kg / h

[0151] · Displacement: 10 sLm (natural exhaust from gap)

[0152] Inlet purge device

[0153] · Purge gas: Nitrogen 40 sLm

[0154] Formation Unit

[0155] · Furnace internal temperature: 800℃

[0156] · Reducing gas: Nitrogen 6 sLm, Hydrogen 54 sLm

[0157] · Total displacement: 90 sLm

[0158] · Processing time: 60 minutes

[0159] Gas mixing prevention device

[0160] · Purge gas: 40 sLm

[0161] · Exhaust system displacement: 40 sLm

[0162] Growth Unit

[0163] · Furnace internal temperature: 830℃

[0164] · Source gas: Nitrogen 30 sLm, Ethylene 10 sLm, Carbon dioxide 2 sLm, Hydrogen 6 sLm

[0165] · Total displacement: 83 sLm

[0166] · Processing time: 10 minutes

[0167] Exit purge device

[0168] · Purge gas: Nitrogen 45 sLm

[0169] cooling unit

[0170] · Cooling temperature: Room temperature

[0171] · Displacement: 10 sLm (natural exhaust from gap)

[0172] Continuous manufacturing was carried out under the above conditions.

[0173] Separation and Recovery Process

[0174] The CNT aggregate synthesized on the substrate is subjected to a forced vortex classifier (rotation speed 2300 rpm, air flow rate 3.5 Nm 3 Separation and recovery were performed using (min). The recovery rate of the CNT aggregate was 96%.

[0175] The characteristics of the obtained CNT aggregate were the same as those of Example 1, and no phenomena of reduced production volume or quality deterioration were observed during continuous manufacturing.

[0176] Thus, according to the apparatus of the present invention, long and high-specific-surface-area CNT aggregates could be continuously manufactured with high efficiency without causing a decrease in production volume or quality deterioration during continuous manufacturing.

[0177] (Example 3)

[0178] Reuse Process

[0179] 3 kg of the used substrate used to manufacture the CNT aggregate in Example 1 was recovered, and a recycling process was performed to remove carbon attached to the surface of the substrate by oxidizing it in a rotary kiln (atmosphere: air, temperature 800°C, treatment time 30 minutes). Using the substrate after the recycling process, each process treatment was performed in the same manner as in Example 1 to manufacture the CNT aggregate.

[0180] Compared to the results of Example 1, the characteristics of the obtained CNT aggregate were approximately the same, except that the quantity was reduced to about 80% to 2.5 mg / g-beads.

[0181] Therefore, it can be seen that, according to Example 3, a long and high specific surface area CNT aggregate could be manufactured by reusing the substrate by the manufacturing method of the present invention.

[0182] (Verification Example)

[0183] Using the same catalyst substrate particles and manufacturing apparatus as in Example 1, the conditions of the formation unit, gas ingress prevention device, and growth unit were each changed as follows, and the CNT aggregate was manufactured under the same conditions as in Example 1 otherwise.

[0184] Formation Unit

[0185] · Furnace internal temperature: 800℃

[0186] · Reducing gas: Nitrogen 6 sLm, Hydrogen 54 sLm

[0187] · Displacement: 70 sLm

[0188] · Processing time: 20 minutes

[0189] Gas mixing prevention device

[0190] · Purge gas: 0 sLm

[0191] · Exhaust system displacement: 0 sLm

[0192] Growth Unit

[0193] · Furnace internal temperature: 830℃

[0194] · Source gas: Nitrogen 15 sLm, Ethylene 5 sLm, Carbon dioxide 1 sLm, Hydrogen 3 sLm

[0195] · Displacement: 79 sLm

[0196] · Processing time: 10 minutes

[0197] As a result, only the surface of the catalyst substrate particles turned dark, and no growth of CNT aggregates was observed.

[0198] Accordingly, it was found that preventing the mixing of raw material gas into the reducing gas is necessary in the manufacture of CNT assemblies.

[0199] Industrial applicability

[0200] According to the present invention, high-quality CNT aggregates can be efficiently produced. Explanation of the symbols

[0201] 100, 200 CNT assembly manufacturing device 101, 201 Inlet Purge Device 102, 202 formation units With 102a and 202a formations 102b, 202b Reduction Gas Injection Device 102c, 202c heating device 102d, 202d exhaust system 103, 203 Gas mixing prevention device 103a, 203a exhaust system 103b, 203b purge gas injection device 104, 204 Growth Units 104a, 204a growth chambers 104b, 204b raw material gas injection device 104c, 104c', 204c heating device 104d, 204d exhaust system 105, 205 Exit Purge Device 106, 206 cooling units 106a, 206a cooling vessels 106b, 206b liquid cooling units 107, 207A, 207B Return Unit 107a, 207A-a, 207B-a screw blades 107b, 207A-b, 207B-b driving device Connection sections 108 ~ 110, 208 ~ 210 111, 211 recorded 112, 212 Hopper 114 Heating device Ex1 ~ Ex3 Raw material gas exhaust ports G1, G2 raw gas inlet

Claims

Claim 1 On a substrate having a catalyst on its surface, a specific surface area of ​​600 m² 2 A method for manufacturing a carbon nanotube assembly for growing a carbon nanotube assembly having a carbon nanotube content of 1g or more, comprising: a formation unit for realizing a formation process in which the surrounding environment of the catalyst is made into a reducing gas environment while simultaneously heating at least one of the catalyst and the reducing gas; a growth unit for realizing a growth process in which the surrounding environment of the catalyst is made into a source gas environment while simultaneously heating at least one of the catalyst and the source gas to grow the carbon nanotube assembly; a connecting part for spatially connecting the furnace space of the formation unit and the furnace space of the growth unit; a first conveying unit for conveying the substrate by screw rotation in the furnace space of the formation unit; and a second conveying unit for conveying the substrate by screw rotation in the furnace space of the growth unit, wherein the first conveying unit and the second conveying unit are configured as one common unit and / or separate units, the first and second conveying units, and the furnace space of the formation unit and the growth unit A method for manufacturing a carbon nanotube assembly, wherein a manufacturing apparatus having a gas mixing prevention device that prevents gases from mixing with each other between spaces within a furnace is used, the substrate is introduced into the manufacturing apparatus through a hopper, the first conveying unit is equipped with a first driving device and the second conveying unit is equipped with a second driving device, the first driving device is disposed at the rear end of the formation unit and the second driving device is disposed at the front end of the growth unit, and the formation process and the growth process are carried out while continuously conveying the substrate and preventing gas environments in each process from mixing with each other. Claim 2 A method for manufacturing a carbon nanotube assembly according to claim 1, wherein the formation unit and the growth unit are separate components and are connected in series by the connection unit. Claim 3 A method for manufacturing a carbon nanotube assembly according to 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. Claim 4 A method for manufacturing a carbon nanotube assembly according to claim 1, wherein, in the formation process, the reducing gas is continuously supplied so that the substrate conveyed by the first conveying unit and the reducing gas come into contact with each other in a counter-flow and counter-flow state, and in the growth process, the raw material gas is continuously supplied so that the substrate conveyed by the second conveying unit and the raw material gas come into contact with each other in a counter-flow and counter-flow state, wherein the reducing gas is continuously supplied. Claim 5 A method for manufacturing a carbon nanotube assembly according to claim 1, wherein the raw material gas environment in the growth process is a high carbon concentration environment and also includes a catalyst activation material. Claim 6 A method for manufacturing a carbon nanotube assembly according to claim 5, wherein the raw material gas environment comprises ethylene and carbon dioxide as the catalyst activation material. Claim 7 In claim 1, the above description has an apparent density of 2.0 g / cm³ 3 A method for manufacturing a carbon nanotube assembly, which is a particle of the above. Claim 8 A method for manufacturing a carbon nanotube assembly according to claim 7, wherein the above description comprises one or more elements among Al, Si, and Zr. Claim 9 A method for manufacturing a carbon nanotube assembly according to any one of claims 1 to 8, comprising: a catalyst layer forming process for forming a catalyst layer on a substrate; a separation and recovery process for separating the carbon nanotube assembly from the substrate and recovering the substrate and the carbon nanotube assembly separately; and a reuse process for making the substrate reusable by oxidizing and removing carbon on the recovered substrate.

Images