A preparation system and method for single-walled carbon nanotubes

Abstract

The present invention belongs to the field of new material technologies, and relates to a preparation system and method for single-walled carbon nanotubes. An ion body component is provided in the furnace body of the preparation system. The ion body component generates two plasma energy fields in the furnace body, and the two plasma energy fields and the discharge port are on the same line. The heights of the two energy fields and the discharge port in the furnace body increase in sequence. Among them, the first plasma energy field completes the evaporation of the catalyst. The evaporated catalyst moves with the carrier gas into the second plasma energy field, and undergoes a catalytic reaction with the cracked carbon source gas to complete the growth of single-walled carbon nanotubes, and enters the collection box through the discharge port to complete the collection. By placing two sets of plasmas in the same chamber, the present invention can avoid the increase in the size of the catalyst and maintain its activity. This method can take into account high quality, high purity and high yield, and has important industrial value.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and particularly relates to a preparation system and method for single-walled carbon nanotubes. Background Art

[0002] Single-walled carbon nanotubes exhibit excellent physical properties due to their unique structure. Currently, the most promising application scenario is to enhance the electrical conductivity of the matrix as an additive. This material can meet the electrical conductivity requirements of the matrix under extremely low addition amounts, and has the characteristic of having little impact on the matrix compared with existing conductive additives. For example, by adding a small amount, the color of the paint itself can be maintained without being affected, while meeting the antistatic requirements. This method is also applicable to resin materials, enabling the material to have a colorful appearance while meeting the electrical conductivity requirements. If materials such as graphite or multi-walled carbon nanotubes are used, in order to achieve the same effect, due to the large addition amount, the product will usually inevitably turn black. Similarly, for materials with requirements for light transmittance, such as antistatic transparent films or transparent conductive glasses, the electrical conductivity requirements can be achieved with little impact on the light transmittance due to the small addition amount. The current largest market should be to replace graphite materials or multi-walled carbon nanotubes in batteries as conductive additives, reducing the impact on the matrix itself through extremely low addition amounts, increasing the battery energy density, and expanding the charge and discharge efficiency.

[0003] In the preparation process of single-walled carbon nanotubes, the plasma method has great advantages for low-cost large-scale preparation due to its large thermal field and high energy utilization rate. In the plasma process, the publicly reported schemes such as application numbers 202222231861.3, 202211173337.3, etc. mainly use ferrocene as the catalyst source. This raw material has poor fluidity, which is not conducive to controlling the catalyst addition amount, and the cost is relatively high, which is not conducive to cost reduction in industrialization. The DC plasma scheme can use metal as the catalyst raw material to reduce the cost and control the catalyst addition amount by adjusting the plasma power. Currently, in this process, it is mainly divided into two routes, namely the one-step method and the two-step method. Among them, the principle of the one-step method is to use the plasma to prepare the catalyst in the same chamber and at the same time use it as a heat source to provide energy for the growth of single-walled carbon nanotubes. The principle of the two-step method is to first prepare catalyst nanoparticles and then transport the prepared catalyst nanoparticles to the growth chamber for the growth of single-walled carbon nanotubes. The problem with the one-step method is that the energy for catalyst evaporation is not the same as the energy for carbon nanotube growth. Using the same plasma as the heat source will cause a mismatch between the two energies. As a result, the evaporated catalyst is much larger than the required amount, while the energy required for the growth of single-walled carbon nanotubes is insufficient, the growth of single-walled carbon nanotubes is slow, and there are a large number of catalyst particles in the product, ultimately resulting in low product purity. The problem with the two-step method is that the catalyst prepared in the catalyst preparation chamber is prone to collide and grow with each other during the process of moving to the growth chamber, that is, the so-called Ostwald ripening occurs. The catalyst particles with increased size often can only grow multi-walled carbon nanotubes with a relatively low degree of graphitization. Summary of the Invention

[0004] The present invention discloses a preparation system and method for single-walled carbon nanotubes to solve any one of the above and other potential problems in the prior art.

[0005] To achieve the above object, the technical solution of the present invention is: A preparation system for single-walled carbon nanotubes, the preparation system includes a furnace body and a collection box. The furnace body is a sealed box, and there is a discharge port at the upper part of one end. The discharge port is communicated with the collection box through a connecting pipeline. A plasma assembly is provided in the furnace body. The plasma assembly generates two plasma energy fields in the furnace body, and the two plasmas are on the same line as the discharge port. The heights of the two plasma energy fields and the discharge port in the furnace body increase in sequence from low to high. Among them, the first plasma energy field completes the evaporation of the catalyst, and the evaporated catalyst moves to the second plasma energy field along with the carrier gas, undergoes a catalytic reaction with the cracked carbon source gas, completes the growth of single-walled carbon nanotubes, and enters the collection box through the discharge port to complete the collection.

[0006] Further, the specific structure of the preparation system is: The furnace body is integrally in a cuboid shape;

[0007] The plasma assembly includes a first plasma and a second plasma. The first plasma and the second plasma are arranged inside the furnace body at a certain distance from each other. One end of the cathodes of the first plasma and the second plasma extends out of the furnace body and is connected to an auxiliary unit for carrier gas and carbon source gas, while the other end is placed inside the furnace body. The anodes of the first plasma and the second plasma are both arranged vertically below the cathodes.

[0008] The discharge port is arranged at the upper end of the side wall of the furnace body near one end of the second plasma. The discharge port is connected to one end of the collection box through a discharge pipe. The other end of the collection box is provided with an exhaust gas outlet, and a exhaust fan is provided on the exhaust gas outlet.

[0009] Furthermore, the power of the second plasma is at least 5 times that of the first plasma.

[0010] The power of the first plasma is 10 - 100 kW, and the power of the second plasma is 50 - 800 kW.

[0011] Furthermore, the height of the furnace cavity on one side of the first plasma is 300 - 500 mm; the height of the furnace cavity on one side of the second plasma is 400 - 700 mm. The lateral distance d1 between the first plasma and the second plasma is 300 mm - 800 mm, and the longitudinal distance d2 is 100 - 200 mm.

[0012] Furthermore, the cathodes of the first plasma and the second plasma are both made of graphite or lanthanum tungsten; the anode of the first plasma is made of iron metal and is placed in a crucible. The anode of the second plasma is made of tantalum, molybdenum, tungsten metal or graphite, and the metal materials need to be placed in a crucible.

[0013] Furthermore, the length of the discharge pipe is 200 - 1000 mm, and the pipe diameter is 80 - 400 mm.

[0014] Furthermore, the volume of the furnace body is 80 - 600 L, and the crucibles are all made of graphite.

[0015] Another object of the present invention is to provide a method for preparing single-walled carbon nanotubes using the above preparation system. The method specifically includes the following steps:

[0016] S1) First, evacuate the inside of the furnace body and replace the air in the equipment with nitrogen or argon.

[0017] S2) Introduce arc-starting gas, turn on the power supplies of the first plasma and the second plasma respectively. The first plasma and the second plasma generate two plasmas with different energies respectively, and raise the furnace temperature to above 1000 °C.

[0018] S3) Pass a certain flow rate of carrier gas through the first plasma, and pass a certain flow rate of carbon source mixed gas through the second plasma. The first plasma completes the evaporation of the catalyst, and the carrier gas transports the evaporated catalyst to the energy field of the second plasma along with the carrier gas, where it undergoes a catalytic reaction with the cracked carbon source gas to obtain a single-walled carbon nanotube aerogel;

[0019] S4) After cooling, the generated single-walled carbon nanotubes continue to move to the discharge port along with the carrier gas and enter the collection box through the discharge pipe, thus obtaining the single-walled carbon nanotube product.

[0020] Furthermore, the carrier gas in S3) is one or more of argon, hydrogen, and nitrogen, and the flow rate is 0.9 - 17 m 3 / h;

[0021] The carbon source mixed gas includes argon, hydrogen, nitrogen, and methane, and the flow rate is 12 - 130 m m 3 / h, where the proportion of hydrogen is 10% - 50%, the proportion of methane is 5% - 25%, the proportion of argon is 50% - 85%, and the proportion of nitrogen is 0 - 20%;

[0022] The catalyst is a metal catalyst, and the metal includes iron.

[0023] Furthermore, the G / D ratio of the single-walled carbon nanotubes is not less than 37, and the purity is not less than 48%.

[0024] The beneficial effects of the present invention are as follows: Due to the adoption of the above technical solution, the system of the present invention can separately control the plasma power used for catalyst preparation and carbon nanotube growth by cracking the carbon source, making the energies required by the two match and meet their respective requirements, avoiding the problem of low product purity caused by excessive catalyst in the existing one-step process. At the same time, it shortens the catalyst transportation distance, improves the transmission temperature field, and reduces the problem of mutual collision and growth during the transmission process, and can prepare single-walled carbon nanotubes that take into account both high graphitization degree and high purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of a double-gun single-chamber single-walled carbon nanotube preparation device of the present invention.

[0026] Figure 2 It is a scanning electron micrograph of the product prepared in Example 1 of the method of the present invention

[0027] Figure 3 It is a Raman spectrum of the product prepared in Example 1 of the method of the present invention.

[0028] Figure 4 It is a thermogravimetric curve of the product prepared in Example 1 of the method of the present invention.

[0029] Figure 5 Scanning electron micrograph of the product prepared in Example 2 of the method of the present invention

[0030] Figure 6 Raman spectrum of the product prepared in Example 2 of the method of the present invention.

[0031] Figure 7 Thermogravimetric curve of the product prepared in Example 2 of the method of the present invention.

[0032] Figure 8 Scanning electron micrograph of the product prepared in Example 3 of the method of the present invention

[0033] Figure 9 Raman spectrum of the product prepared in Example 3 of the method of the present invention.

[0034] Figure 10 Thermogravimetric curve of the product prepared in Example 3 of the method of the present invention.

[0035] Figure 11 Schematic structural diagram of the carbon nanotube preparation device in Comparative Example 1

[0036] Figure 12 Scanning electron micrograph of the product prepared in Comparative Example 1

[0037] Figure 13 Schematic diagram of the thermogravimetric curve of the product prepared in Comparative Example 1

[0038] Figure 14 Schematic structural diagram of a double-gun and double-chamber carbon nanotube preparation device

[0039] Figure 15 Scanning electron micrograph of the product prepared in Comparative Example 2 of the method of the present invention

[0040] Figure 16 Raman spectrum of the product prepared in Comparative Example 2 of the method of the present invention.

[0041] In the figure:

[0042] 9. Growth chamber; 10. Evaporation chamber; 11. Cathode of the first plasma; 12. Anode of the first plasma; 20. Transfer tube; 21. Cathode of the second plasma; 22. Anode of the second plasma; 30. Furnace body; 40. Discharge pipe; 50. Collection box Detailed implementation manners

[0043] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0044] As Figure 1As shown in the figure, a preparation system for single-walled carbon nanotubes according to the present invention includes a furnace body and a collection box. The furnace body 30 is a sealed box body, and there is a discharge port at the upper part of one end. The discharge port is communicated with the collection box 50 through a connecting pipeline. A plasma component is provided inside the furnace body 30. The plasma component generates two plasma energy fields inside the furnace body, and the two plasmas are on the same line as the discharge port. The heights of the two plasma energy fields and the discharge port inside the furnace body increase in sequence from low to high. Among them, the first plasma energy field completes the evaporation of the catalyst. After evaporation, the catalyst moves to the second plasma energy field along with the carrier gas, and undergoes a catalytic reaction with the cracked carbon source gas to complete the growth of single-walled carbon nanotubes, and enters the collection box through the discharge port to complete the collection.

[0045] The specific structure of the preparation system is as follows: The furnace body 30 is generally in a cuboid shape;

[0046] The plasma component includes a first plasma and a second plasma. The first plasma and the second plasma are arranged at a certain distance inside the furnace body. Among them, one end of the cathode 11 of the first plasma and the cathode 21 of the second plasma extends out of the furnace body 30 and is connected to an auxiliary unit for carrier gas and carbon source gas, and the other end is placed inside the furnace body 30. The anodes 12 of the first plasma and 22 of the second plasma are both arranged vertically below the cathode;

[0047] The discharge port is arranged at the upper end of the side wall of the furnace body 30 near one end of the second plasma. The discharge port is connected to one end of the collection box 50 through a discharge pipe 40. The other end of the collection box 50 is provided with an exhaust gas outlet, and an exhaust fan is provided on the exhaust gas outlet.

[0048] The power of the second plasma is at least 5 times that of the first plasma;

[0049] The power of the first plasma is 10 - 100 kW, and the power of the second plasma is 50 - 800 kW.

[0050] The height of the furnace cavity on one side of the first plasma is 300 - 500 mm; the height of the furnace cavity on one side of the second plasma is 400 - 700 mm. The lateral distance d1 between the first plasma and the second plasma is 300 mm - 800 mm, and the longitudinal distance d2 is 100 - 200 mm.

[0051] The cathodes 11 of the first plasma and 21 of the second plasma are both made of graphite or lanthanum tungsten; the anode 12 of the first plasma is made of iron metal and is contained in a crucible, and the anode 22 of the second plasma is made of tantalum, molybdenum, tungsten metal or graphite, and the metal materials need to be contained in a crucible.

[0052] The length of the discharge pipe is 200 - 1000 mm, and the pipe diameter is 80 - 400 mm.

[0053] The volume of the furnace body 30 is 80 - 600 L, and the crucibles are all made of graphite.

[0054] A method for preparing single-walled carbon nanotubes using the above preparation system, which specifically includes the following:

[0055] S1) First, evacuate the inside of the furnace body 30, and replace the air in the equipment with nitrogen or argon;

[0056] S2) Introduce the arc-starting gas, connect the power supplies of the first plasma and the second plasma respectively. The first plasma and the second plasma generate two plasmas with different energies respectively, and raise the furnace temperature to above 1000 °C;

[0057] S3) Pass a certain flow rate of carrier gas through the first plasma respectively, and pass a certain flow rate of carbon source mixed gas through the second plasma. The first plasma completes the evaporation of the catalyst, and the carrier gas moves the evaporated catalyst to the energy field of the second plasma along with the carrier gas and undergoes a catalytic reaction with the cracked carbon source gas to obtain a single-walled carbon nanotube aerogel;

[0058] S4) After cooling, the generated single-walled carbon nanotubes continue to move to the discharge port along with the carrier gas, and enter the collection box through the discharge pipe, that is, the single-walled carbon nanotube product is obtained.

[0059] The carrier gas in S3) is one or more of argon, hydrogen, and nitrogen, and the flow rate is 0.9 - 17 m 3 / h;

[0060] The carbon source mixed gas includes argon, hydrogen, nitrogen, and methane, and the flow rate is 12 - 130 m m 3 / h, where the proportion of hydrogen is 10% - 50%, the proportion of methane is 5% - 25%, the proportion of argon is 50% - 85%, and the proportion of nitrogen is 0 - 20%;

[0061] The catalyst is a metal catalyst, and the metal includes iron.

[0062] The G / D ratio of the single-walled carbon nanotubes is not less than 37. The purity is not less than 48%.

[0063] Example 1

[0064] Using the double-gun single-chamber single-wall carbon nanotube preparation device as shown in Figure 1 Figure 1, it is composed of a furnace body 30, a collection box 50 and a discharge pipe 40 connecting the two. There are two sets of independent plasmas in the furnace body 30. The power of the first plasma is 30 kW, and the power of the second plasma is 200 kW. The diameter of the region where the first plasma is located is 350 mm, and the height is 350 mm. The diameter of the region where the second plasma is located is 500 mm, and the height is 500 mm. The horizontal distance between the two is 500 mm, and the vertical distance is 150 mm. The cathodes of the two sets of plasmas are made of graphite. Among them, the anode 12 of the first plasma is made of iron metal, and the anode 22 of the second plasma is made of molybdenum metal. The diameter of the discharge pipe is 200 mm, and the length is 500 mm. The diameter of the collection box is 1200 mm, and the height is 1200 mm. 40 L of argon and 40 L of hydrogen are introduced into the cathode 11 of the first plasma, and 200 L of argon, 100 L of hydrogen, and 20 L of nitrogen are introduced into the cathode 21 of the second plasma. The furnace temperature is raised to 1600 °C, and the gas flow of the second plasma is changed to 200 L of argon, 100 L of hydrogen, and 30 L of methane for reaction. The grown product enters the collection box through the discharge pipe.

[0065] Figure 2 Scanning electron micrograph of the product prepared in Example 1 of the method of the present invention; Figure 3 Raman spectrum of the product prepared in Example 1 of the method of the present invention, and the G / D ratio is 37. Figure 4 Thermogravimetric curve of the product prepared in Example 1 of the method of the present invention, and the purity is 48%.

[0066] Example 2

[0067] Using the double-gun single-chamber single-wall carbon nanotube preparation device as shown in Figure 1 Figure 1, it is composed of a furnace body 30, a collection box 50 and a discharge pipe 40 connecting the two. There are two sets of independent plasmas in the furnace body. The power of the first plasma is 10 kW, and the power of the second plasma is 100 kW. The diameter of the region where the first plasma is located is 250 mm, and the height is 250 mm. The diameter of the region where the second plasma is located is 350 mm, and the height is 350 mm. The horizontal distance between the two is 400 mm, and the vertical distance is 100 mm. The cathode 11 of the first plasma is a graphite electrode, and the anode is made of iron metal. The cathode 21 of the second plasma is a lanthanum tungsten electrode, and the anode is made of tungsten metal. The diameter of the discharge pipe is 100 mm, and the length is 200 mm. The diameter of the collection box 50 is 600 mm, and the height is 600 mm. 20 L of argon and 20 L of hydrogen are introduced into the cathode 11 of the first plasma, and 100 L of argon, 50 L of hydrogen, and 10 L of nitrogen are introduced into the cathode 21 of the second plasma. The furnace temperature is raised to 1100 °C, and the gas flow of the second plasma is changed to 100 L of argon, 50 L of hydrogen, and 10 L of methane for reaction. The grown product enters the collection box through the discharge pipe.

[0068] Figure 5 Scanning electron micrograph of the product prepared in Example 1 of the method of the present invention; Figure 6 Raman spectrum of the product prepared in Example 1 of the method of the present invention, with a G / D ratio of 48. Figure 7 Thermogravimetric curve of the product prepared in Example 1 of the method of the present invention, with a purity of 59%.

[0069] Example 3

[0070] Using the Figure 1 double-gun single-chamber single-wall carbon nanotube preparation device shown, which consists of a furnace body 30, a collection box 50 and a discharge pipe 40 connecting the two. There are two sets of independent plasmas in the furnace body 30. The power of the first plasma is 20 kW, and the power of the second plasma is 150 kW. The diameter of the region where the first plasma is located is 300 mm and the height is 300 mm. The diameter of the region where the second plasma is located is 400 mm and the height is 400 mm. The horizontal distance between the two is 450 mm, and the vertical distance is 120 mm. The cathodes of the two sets of plasmas are made of graphite. Among them, the anode 12 of the first plasma is made of iron metal, and the anode 22 of the second plasma is made of graphite. The diameter of the discharge pipe is 150 mm and the length is 350 mm. The diameter of the collection box is 800 mm and the height is 800 mm. 30 L of argon and 30 L of hydrogen are introduced into the cathode 11 of the first plasma, and 150 L of argon, 80 L of hydrogen and 15 L of nitrogen are introduced into the cathode 22 of the second plasma. The furnace temperature is raised to 1300 °C, and the gas flow of the 2nd plasma is changed to 150 L of argon, 80 L of hydrogen and 20 L of methane for reaction. The grown product enters the collection box through the discharge pipe.

[0071] Figure 8 Scanning electron micrograph of the product prepared in Example 1 of the method of the present invention; Figure 9 Raman spectrum of the product prepared in Example 1 of the method of the present invention, with a G / D ratio of 37. Figure 10 Thermogravimetric curve of the product prepared in Example 1 of the method of the present invention, with a purity of 53%.

[0072] Comparative Example 1

[0073] Using the Figure 11The shown single-gun and single-chamber carbon nanotube preparation device is composed of a furnace body 30, a collection box 50 and a discharge pipe 40 connecting the two. There is a set of plasma device in the furnace body 30 with a power of 110 kW. The inner diameter of the furnace is 800 mm and the height is 900 mm. The cathode is made of graphite material and the anode is made of iron metal. The diameter of the discharge pipe is 100 mm and the length is 200 mm. The diameter of the collection box is 600 mm and the height is 900 mm. 100 L of argon, 50 L of hydrogen and 10 L of nitrogen are introduced into the cathode, the furnace temperature is raised to 1100 °C, and the gas flow of the No. 2 plasma is changed to 100 L of argon, 50 L of hydrogen and 10 L of methane for reaction. The grown products enter the collection box 50 through the discharge pipe.

[0074] Figure 12 Scanning electron micrograph of the product prepared in Comparative Example 1 of the method of the present invention; Figure 13 Thermogravimetric curve of the product prepared in Comparative Example 1 of the method of the present invention, with a purity of 6%.

[0075] This scheme uses a set of plasma as both the catalyst preparation and the energy source for single-walled carbon nanotube growth. In order to provide sufficient energy for single-walled carbon nanotubes, it is necessary to increase the plasma power, and this adjustment will increase the generation amount of the catalyst, resulting in excessive catalyst residue in the product.

[0076] Comparative Example 2

[0077] Adopt as Figure 14 The shown double-gun and double-chamber carbon nanotube preparation device is composed of an evaporation chamber 10, a growth chamber 9, a collection box 50 and a discharge pipe 40 connecting the three. There are two sets of independent plasmas in the device. The power of the No. 1 plasma is 10 kW, and the power of the No. 2 plasma is 100 kW. The diameter of the area where the first plasma is located is 300 mm and the height is 500 mm. The diameter of the area where the second plasma is located is 800 mm and the height is 900 mm. The horizontal distance between the two is 1000 mm and the vertical distance is 200 mm. The cathode of the No. 1 plasma is a graphite electrode and the anode is made of iron metal. The cathode of the No. 2 plasma is a lanthanum tungsten electrode and the anode is made of tungsten metal. The diameter of the transfer pipe is 100 mm and the length is 450 mm. The diameter of the discharge pipe is 100 mm and the length is 200 mm. The diameter of the collection box is 400 mm and the height is 600 mm. 20 L of argon and 20 L of hydrogen are introduced into the cathode of the No. 1 plasma, 100 L of argon, 50 L of hydrogen and 10 L of nitrogen are introduced into the cathode of the No. 2 plasma, the furnace temperature is raised to 1100 °C, and the gas flow of the No. 2 plasma is changed to 100 L of argon, 50 L of hydrogen and 10 L of methane for reaction. The grown products enter the collection box through the discharge pipe.

[0078] Figure 15 Scanning electron micrograph of the product prepared in Comparative Example 2 of the method of the present invention; Figure 16Raman spectrum of the product prepared in Comparative Example 2 of the method of the present invention, with a G / D ratio of 1.78.

[0079] In this scheme, two sets of plasmas are placed in two chambers and transported through a pipeline in the middle. Due to the increase in the transmission distance, the phenomenon of catalyst particle accelerated Ostwald ripening occurs during the transmission process, and the size grows rapidly, resulting in the main growth of the product being multi-walled carbon nanotubes and the G / D ratio decreasing.

[0080] The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present application.

[0081] As used in the specification and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not use the difference in names as a way to distinguish components, but use the difference in functions of components as the criterion for distinction. As used throughout the specification and claims, the terms "comprising" and "including" are open-ended terms and should be interpreted as "comprising / including but not limited to". "Substantially" means within an acceptable error range. Those skilled in the art can solve the technical problems within the preset error range and basically achieve the technical effects. The subsequent description of the specification is for the purpose of describing the preferred embodiments of the present application, but the description is for the purpose of explaining the general principles of the present application and is not intended to limit the scope of the present application. The protection scope of the present application shall be determined by the scope defined by the appended claims.

[0082] It should also be noted that the term "including" or "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a commodity or system including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a commodity or system. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the commodity or system including the said element.

[0083] It should be understood that the term "and / or" used herein is only a relationship describing associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0084] The foregoing description has shown and described several preferred embodiments of the present application. However, as previously mentioned, it should be understood that the present application is not limited to the forms disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications, and environments, and can be changed within the scope of the application concept described herein through the above teachings or the techniques or knowledge in the relevant field. Any changes and variations made by those skilled in the art without departing from the spirit and scope of the present application shall fall within the protection scope of the appended claims of the present application.

Claims

1. A preparation system for single-walled carbon nanotubes, the preparation system comprising a furnace body and a collection box, the furnace body being a sealed box body, and an upper part of one end being provided with a discharge port, the discharge port being communicated with the collection box through a connecting pipeline, characterized in that, A plasma assembly is provided inside the furnace body. The plasma assembly includes a first plasma and a second plasma. The first plasma and the second plasma are arranged inside the furnace body at a certain distance apart. Among them, one end of the cathodes of the first plasma and the second plasma extends out of the furnace body and is respectively connected to an auxiliary unit for carrier gas and carbon source gas, and the other end is placed inside the furnace body. The anodes of the first plasma and the second plasma are both arranged vertically below the cathodes; The first plasma and the second plasma generate two plasma energy fields with different energies inside the furnace body, and the two plasma energy fields and the discharge port are on the same line. The heights of the two plasma energy fields with different energies and the discharge port inside the furnace body increase in sequence from low to high. Among them, the first plasma energy field completes the evaporation of the catalyst. The evaporated catalyst moves with the carrier gas into the second plasma energy field and undergoes a catalytic reaction with the cracked carbon source gas to complete the growth of single-walled carbon nanotubes, and enters the collection box through the discharge port to complete the collection.

2. The preparation system according to claim 1, characterized in that, The discharge port is arranged at the upper end of the side wall of the furnace body near one end of the second plasma. The discharge port is connected to one end of the collection box through a discharge pipe. The other end of the collection box is provided with an exhaust gas outlet, and an exhaust fan is provided on the exhaust gas outlet.

3. The preparation system according to claim 2, characterized in that, The power of the second plasma is at least 5 times that of the first plasma; The power of the first plasma is 10 - 100 kW, and the power of the second plasma is 50 - 800 kW.

4. The preparation system according to claim 2, characterized in that, The height of the furnace cavity on one side of the first plasma is 300 - 500 mm; the height of the furnace cavity on one side of the second plasma is 400 - 700 mm. The lateral distance d1 between the cathodes of the first plasma and the second plasma is 300 mm - 800 mm, and the longitudinal distance d2 between the bottom ends of the cathodes of the first plasma and the second plasma is 100 - 200 mm.

5. The preparation system according to claim 2, wherein The cathodes of the first plasma and the second plasma are both made of graphite or lanthanum tungsten; the anode of the first plasma is made of iron metal and is placed in a crucible. The anode of the second plasma is made of tantalum, molybdenum, tungsten metal or graphite, and the metal material needs to be placed in a crucible.

6. The preparation system according to claim 2, wherein The length of the discharge pipe is 200 - 1000 mm, and the pipe diameter is 80 - 400 mm.

7. The preparation system according to claim 5, characterized in that, The volume of the furnace body is 80 - 600 L, and the crucibles are all made of graphite.

8. A method for preparing single-walled carbon nanotubes using the preparation system according to any one of claims 1-7, characterized in that, Specifically, it includes the following: S1) First, evacuate the inside of the furnace body and replace the air in the equipment with nitrogen or argon; S2) Introduce the arc-starting gas, and respectively turn on the power supplies of the first plasma and the second plasma. The first plasma and the second plasma respectively generate two plasma energy fields with different energies, and raise the furnace temperature to above 1000 °C; S3) Introduce a certain flow rate of carrier gas through the first plasma and a certain flow rate of carbon source mixed gas through the second plasma. Evaporate the catalyst within the energy field of the first plasma, and move the evaporated catalyst with the carrier gas to the energy field of the second plasma to undergo a catalytic reaction with the cracked carbon source gas, obtaining a single-walled carbon nanotube aerogel; S4) After cooling, the generated single-walled carbon nanotubes continue to move with the carrier gas to the discharge port and enter the collection box through the discharge pipe, thus obtaining the single-walled carbon nanotube product.

9. The method according to claim 8, wherein The carrier gas in the step S3) is one or more of argon, hydrogen, and nitrogen, and the flow rate is 0.9-17 m 3 / h; The flow rate of the carbon source mixed gas is 12 - 130 m 3 / h. The proportion of hydrogen in the carbon source mixed gas is 10% - 50%, the proportion of methane is 5% - 25%, the proportion of argon is 50% - 85%, and the proportion of nitrogen is 0 - 20%; The catalyst is a metal catalyst, and the metal catalyst is iron.

10. According to the method described in claim 8 or 9, the G / D ratio of the single-walled carbon nanotubes is not less than 37, and the purity is not less than 48%.

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