Carbon material preparation device and preparation method

Abstract

The invention belongs to the technical field of carbon nanomaterial preparation, and relates to a carbon material preparation device and method, the device specifically comprises a reaction furnace, and the reaction furnace is provided with a first plasma generator, a second plasma generator, a catalyst melting cavity and an extension reaction section; the first plasma generator is arranged on one side of the reaction furnace, and the extension reaction section is arranged on the other side, opposite to the first plasma generator, of the reaction furnace; a nozzle of the first plasma generator faces the extension reaction section; the second plasma generator is arranged at the upper part of the reaction furnace, the catalyst melting cavity is arranged at the bottom in the reaction furnace, and a nozzle of the second plasma generator is opposite to the catalyst melting cavity; the catalyst melting cavity is connected with a bottom electrode penetrating through the bottom of the reaction furnace. According to the device, the yields of the carbon nanoparticles and the iron nanoparticles are respectively controllable, and the optimal production speed can be achieved by independently adjusting the two sets of plasma generators.

Description

Technical Field

[0001] The invention relates to the technical field of carbon nanomaterial preparation, and specifically discloses a carbon material preparation device and a preparation method. Background Art

[0002] Carbon materials are widely used in energy, electronics, environmental protection, medical and other fields due to their structural diversity. In particular, carbon nanotubes (CNTs), as a new type of material with unique one-dimensional nanostructure and excellent physical and chemical properties, have received widespread attention since their discovery. Their high conductivity, high mechanical strength, large specific surface area and good chemical stability make them show great application potential in composite materials, electronic devices, energy storage (such as lithium-ion batteries and supercapacitors), catalyst carriers and other fields. However, the large-scale production and commercial application of carbon nanotubes still face many technical bottlenecks, especially the efficiency and controllability of the production process, the optimization of equipment design and the control of production costs.

[0003] At present, the industrial production of carbon materials such as carbon nanotubes mainly relies on chemical vapor deposition (CVD), the basic principle of which is to generate carbon atoms and self-assemble to form nanotube structures by cracking carbon source gas (such as methane, ethylene, etc.) on the surface of catalyst (such as transition metal iron, cobalt, nickel or their alloys). The catalysts used in existing carbon nanotube production devices are mostly iron oxides, whose catalytic rate is not as good as iron atoms or iron nanoparticles, but the preparation of iron atoms or iron nanoparticles is more difficult, and the chemical activity is high and difficult to preserve; in addition, when plasma-assisted CVD production is used, a single plasma generator is used to generate high temperature in the same area to crack the carbon source gas and vaporize the iron-based catalyst, which makes it difficult to control the output of iron materials. Summary of the invention

[0004] The purpose of the present invention is to provide a carbon material preparation device and a preparation method, which solves the problem that it is difficult to directly use iron atoms or iron nanoparticles as catalysts and the problem that the output of carbon materials is difficult to control; the specific scheme is as follows: In a first aspect, a carbon material preparation device is provided, comprising a reaction furnace, wherein the reaction furnace is provided with a first plasma generator, a second plasma generator, a catalyst melting cavity, and an extended reaction section; The first plasma generator is arranged on one side of the reaction furnace, and the extended reaction section is arranged on the other side of the reaction furnace opposite to the first plasma generator; the nozzle of the first plasma generator faces the extended reaction section; The second plasma generator is arranged at the upper part of the reaction furnace, the catalyst melting cavity is arranged at the bottom of the reaction furnace, and the nozzle of the second plasma generator is opposite to the catalyst melting cavity; The catalyst melting cavity is connected with a bottom electrode penetrating the bottom of the reaction furnace.

[0005] Furthermore, the first plasma generator is a non-transferred arc generator, and the nozzle of the first plasma generator is flush with the inner wall of the reaction furnace.

[0006] Furthermore, the second plasma generator is a transferred arc generator, which is fixed to the upper part of the reaction furnace through a first dynamic sealing flange group; the nozzle of the second plasma generator is 3-5 cm away from the catalyst melting cavity.

[0007] Furthermore, the catalyst melting chamber is embedded in the bottom of the reactor, and its opening is flush with the bottom of the reactor; the catalyst melting chamber is made of iron metal. When working, it is energized or grounded through the bottom electrode to generate an arc between the cathode of the second plasma generator.

[0008] Furthermore, it also includes a powder delivery pipe, which is arranged at the upper part of the reactor, and the powder outlet of the powder delivery pipe is close to and directly faces the arc zone between the cathode of the second plasma generator and the catalyst melting cavity; the powder delivery pipe is also wrapped with a powder delivery pipe cooling water jacket.

[0009] Furthermore, it also includes an electrode connection port and a bottom electrode cooling water jacket wrapped around the bottom electrode, the bottom electrode cooling water jacket is provided with a notch for connecting the electrode connection port with the bottom electrode; the bottom electrode is fixed to the bottom of the reactor by a second dynamic sealing flange group.

[0010] Furthermore, it also includes a first temperature and pressure measuring device and a second temperature and pressure measuring device, wherein the first temperature and pressure measuring device is arranged in the reaction furnace, and the second temperature and pressure measuring device is arranged in the extended reaction section.

[0011] In a second aspect, a method for preparing a carbon material is provided, the method comprising: In the cracking section of the reaction furnace, the carbon source gas is cracked by a first plasma generator to produce carbon nanoparticles, and the carbon nanoparticles are blown to the vaporization section and the extended reaction section in sequence; In the vaporization section of the reaction furnace, the iron melt in the catalyst melting cavity is vaporized by a second plasma generator to form iron atoms; The carbon nanoparticles passing through the vaporization section are mixed with the iron atoms produced in the vaporization section and enter the extended reaction section to produce carbon materials.

[0012] Furthermore, the first plasma generator is a non-transferred arc generator, and the working gas introduced therein is a mixture of carbon source gas and argon gas, wherein the volume proportion of the carbon source gas is 5%-30%; the flame temperature of the first plasma generator is 1800-2500 degrees Celsius; and the temperature of the cracking section is higher than 1500 degrees Celsius.

[0013] Furthermore, the second plasma generator is a transferred arc generator, which uses argon as a working gas. A plasma arc is formed between its cathode and the catalyst melting cavity. The iron powder entering the reactor through the powder feeding pipe falls into the catalyst melting cavity through the plasma arc to form molten iron. The molten iron is vaporized under high temperature to form iron atoms free in the vaporization section. The temperature inside the catalyst melting cavity is 2750-3000 degrees Celsius.

[0014] Beneficial effects: The device and method provided by the present invention allows the vaporization of molten iron and the cracking of carbon source gas to be carried out separately. The first plasma generator is mainly used to crack the carbon source gas to produce carbon nanoparticles, and the second plasma generator is mainly used to vaporize the molten iron to produce iron atoms or iron nanoparticles; the output of carbon nanoparticles and iron nanoparticles can be controlled separately, and the optimal production speed can be achieved through adjustment. At the same time, the speed control of the jet flame airflow is achieved by controlling the output power of the first plasma generator, and a laminar airflow can be formed by setting the position of the first plasma generator and the extended reaction section, so that the mixed carbon nanoparticles and iron nanoparticles move more smoothly in the extended reaction section to avoid blocking the reaction channel of the extended reaction section. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A carbon material production device used in the prior art; Figure 2 A carbon material production device provided by the present invention; Figure 3 A method for producing carbon materials provided by the present invention; Figure 4 This is an electron microscope image of single-walled carbon nanotubes produced by the carbon material production device provided by the present invention.

[0016] Figure numerals: 1. first temperature and pressure measuring device, 2. cracking plasma flame, 3. carbon source gas nozzle, 4. carbon source gas delivery pipe, 5. first plasma generator anode cooling water inlet, 6. first plasma generator anode cooling water outlet, 7. carbon source gas inlet, 8. first plasma generator cathode cooling water inlet, 9. first plasma generator cathode cooling water outlet, 10. first plasma generator, 11. thermal insulation layer, 12. second plasma generator cooling water outlet, 13. Second plasma generator cooling water inlet, 14. Argon gas inlet, 15. Second plasma generator, 16. First dynamic sealing flange group, 17. Powder feeding pipe feeding port, 18. Powder feeding pipe cooling water inlet, 19. Powder feeding pipe cooling water outlet, 20. Powder feeding pipe, 21. Bottom electrode, 22. Electrode connecting port, 23. Bottom electrode cooling water inlet, 24. Bottom electrode cooling water outlet, 25. Second dynamic sealing flange group, 26. Catalyst melting cavity, 27. Transfer arc column, 28. Carbon material generation initial reaction area, 29. Extended reaction section outlet, 30. Extended reaction section, 31. Extended reaction section tubular furnace body, 32. Second temperature and pressure measuring equipment, 33. Cracking gas, 34. Mixed gas. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0018] Carbon materials mainly include high-value materials such as graphene, carbon nanotubes, and carbon fibers. The carbon materials referred to in this application mainly refer to carbon nanotubes, especially the continuous and efficient preparation of single-walled carbon nanotubes. The following embodiments are all described using carbon nanotubes as an example. Figure 1 As shown, the existing device for preparing carbon nanotubes by plasma generator-assisted CVD method uses a single non-transferred arc plasma generator to maintain the high-temperature reaction environment in the reactor, so that the introduced carbon source gas is cracked to form carbon nanoparticles or carbon black, and the iron compound on the carrier is used as a catalyst for the growth of carbon nanotubes. The device uses a single plasma generator to maintain the high-temperature reaction environment, so that the cracked carbon source gas and the catalyst are located in the same area, so that the quality of the produced carbon nanotubes is unstable; in addition, the quality of the iron compound is fixed and cannot be continuously increased, so that the carbon nanotubes that can be generated are limited, and only the intake amount of the carbon source gas can be controlled, and the control of the generation rate of the carbon nanotubes is limited; it can be seen that the production capacity of the carbon nanotube preparation device in the prior art is limited, and it is difficult to apply in industrial production scenarios.

[0019] Based on the above problems of the prior art, the present invention intends to provide a new device and method for preparing carbon nanotubes using a plasma generator-assisted CVD method; in order to solve the problem of difficulty in directly using iron atoms or iron nanoparticles as catalysts and difficulty in controlling the yield of iron nanotubes.

[0020] Example 1 This embodiment mainly describes the structure and working principle of the carbon nanotube preparation device provided by the present invention. Figure 2 As shown, it includes a reaction furnace, on which a first plasma generator, a second plasma generator, a catalyst melting cavity, and an extended reaction section are arranged; since the temperature inside the reaction furnace and the extended reaction section is extremely high, the furnace wall of the reaction furnace and the inner wall of the extended reaction section should be made of high-temperature resistant materials, and in order to reduce energy consumption, the reaction furnace and the extended reaction section are also wrapped with a thermal insulation layer.

[0021] The first plasma generator is arranged on one side of the reaction furnace, and the extended reaction section is arranged on the other side of the reaction furnace opposite to the first plasma generator; the nozzle of the first plasma generator faces the extended reaction section; specifically, Figure 2 In the embodiment, the first plasma generator is arranged on the right side of the reaction furnace, and the extended reaction section is arranged on the left side of the reaction furnace; the cross-section of the reaction channel of the extended reaction section (the cross-section is perpendicular to the axis of the reaction channel) can be rectangular or circular, preferably circular, which can be cleaned and the produced carbon nanotubes can move more smoothly to the outlet of the extended reaction section.

[0022] In one embodiment, the first plasma generator is arranged on one side of the reaction furnace (such as Figure 2 There is a certain height difference between the bottom of the reactor and the reaction channel of the extended reaction section, and a slope is set at the connection to guide the airflow into the extended reaction section; the height difference is about 3-8cm. The setting of the slope can avoid the formation of turbulence at the connection, making it difficult for the produced carbon nanotubes to be discharged from the extended reaction section and cause blockage.

[0023] The second plasma generator is arranged at the upper part of the reaction furnace, the catalyst melting cavity is arranged at the bottom of the reaction furnace, and the nozzle of the second plasma generator is opposite to the catalyst melting cavity; Figure 2 As shown, in one embodiment, the nozzle of the second plasma generator is located directly above the catalyst melting cavity, and the nozzle of the second plasma generator is 3-5 cm away from the inner wall of the catalyst melting cavity; the reactor area where the catalyst melting cavity is located is defined as a vaporization section, and the area between the first plasma generator and the catalyst melting cavity is defined as a cracking section.

[0024] In one embodiment, the nozzle direction of the first plasma generator and the nozzle direction of the second plasma generator are in the same plane and perpendicular.

[0025] The catalyst melting chamber is connected to a bottom electrode that passes through the bottom of the reaction furnace. During use, the bottom electrode is grounded or connected to a power source.

[0026] In one embodiment, the extended reaction section is integrated with the reactor, which has a better heat preservation effect; but it is not conducive to maintenance; therefore, another possible embodiment is as follows Figure 2 As shown, the extended reaction section is connected to the reaction furnace through a flange.

[0027] In order to more clearly understand the working mode of the present invention, the following further explanation is given. The first plasma generator is a non-transferred arc generator. In order to extend its service life, its anode and cathode are both provided with independent water cooling channels; and in order to avoid the influence of high temperature in the reactor, it is a preferred embodiment that the nozzle of the first plasma generator is flush with the inner wall of the reactor.

[0028] The catalyst melting chamber is embedded in the bottom of the reactor, and its opening is flush with the bottom of the reactor. The catalyst melting chamber is made of iron metal, that is, the catalyst melting chamber can be understood as an iron dry pot with an inner cavity. When working, it is connected to a power source or grounded through the bottom electrode, thereby generating an arc between the cathode of the second plasma generator.

[0029] Since the second plasma generator needs to generate a high-temperature arc between it and the catalyst melting chamber, the second plasma generator should be a transferred arc generator, which is fixed to the upper part of the reactor through the first dynamic sealing flange group; the nozzle of the second plasma generator is generally 3-5 cm away from the inner wall of the catalyst melting chamber, and this distance facilitates the transfer arc column to hit the inner wall of the catalyst melting chamber; and the vaporization section where the second plasma generator and the catalyst melting chamber are located is close to the extended reaction section.

[0030] Combined with the positional relationship between the first plasma generator, the second plasma generator, and the extended reaction section in the reactor, it can be determined that the first plasma generator can realize the cracking of the carbon source gas in the cracking section to produce carbon nanoparticles, and the high-temperature arc generated between the second plasma generator and the catalyst melting cavity in the vaporization section can liquefy the iron powder to obtain molten iron, and make the molten iron vaporize the molten iron at a certain controllable rate (achieved by adjusting the power of the second plasma generator) to produce gaseous iron atoms or iron particles (because the vaporized iron atoms float in the vaporization section away from the high-temperature arc generated between the second plasma generator and the catalyst melting cavity, they will solidify into iron particles due to the decrease in temperature). The carbon nanoparticles flow to the vaporization section through the airflow generated by the flame of the first plasma generator, and after mixing with iron atoms or iron particles in the vaporization section, they enter the extended reaction section with the airflow, and in the extended reaction section, the carbon nanoparticles use the iron particles as catalysts and grow on their surface to form carbon nanotubes; it should be noted that the vaporization section is also the initial reaction area for carbon material production, and the extended reaction section is specifically composed of the extended reaction section tank furnace body.

[0031] Due to the need to achieve continuous production, the present invention does not adopt the method of placing iron-based compounds such as iron powder in the catalyst melting chamber in advance. The purpose of setting up the second plasma generator is to require controllable vaporization of the molten iron. Although the catalyst melting chamber is made of metallic iron (which can avoid the generation of other impurities during the reaction), in order to avoid its excessive consumption, a powder delivery pipe for adding iron powder in real time needs to be set.

[0032] Specifically, the powder feeding pipe is arranged at the upper part of the reactor, and its powder outlet is close to and directly faces the arc zone between the cathode of the second plasma generator and the catalyst melting cavity; the arrangement of the powder feeding pipe allows the iron powder feeding amount to be adjusted in real time according to the carbon nanotube production and other conditions. Since the part of the powder feeding pipe with the outlet passes through the reactor inside the furnace, in order to extend its service life, the powder feeding pipe is also wrapped with a powder feeding pipe cooling water jacket, which is used to cool the powder feeding pipe.

[0033] When the device is working, a large current passes through the bottom electrode, and the heat in the catalyst melting chamber is also conducted to the bottom electrode; therefore, a bottom electrode cooling water jacket is also wrapped on the bottom electrode; the bottom electrode cooling water jacket is provided with a notch for connecting the electrode connecting port with the bottom electrode, and the electrode connecting port serves as a connector for connecting the power electrode with the bottom electrode, and its setting facilitates the plugging and unplugging of the power electrode, so as to facilitate equipment maintenance and transportation; since the reactor is in a state of high temperature and high pressure, in order to ensure sealing, the bottom electrode is fixed to the bottom of the reactor through a second dynamic sealing flange group.

[0034] When the device of the present invention is used to produce carbon nanotubes, the amount of carbon source gas, the amount of iron powder, and the power of the first plasma generator and the second plasma generator are all controllable. Therefore, the controllability is relatively strong when producing carbon nanotubes. In order to form relevant control basis, especially the control basis of the power of the first plasma generator and the second plasma generator, the present invention is also provided with a first temperature and pressure measuring device and a second temperature and pressure measuring device, wherein the first temperature and pressure measuring device is arranged in the cracking section of the reactor, and the second temperature and pressure measuring device is arranged in the extension reaction section.

[0035] The above-mentioned device structure allows the vaporization of molten iron and the cracking of carbon source gas to be carried out separately. The first plasma generator is mainly used to crack the carbon source gas to produce carbon nanoparticles, and the second plasma generator is mainly used to vaporize the molten iron to produce iron atoms or iron nanoparticles. This design can make the output of carbon nanoparticles and iron nanoparticles respectively controllable, and the optimal production speed can be achieved through adjustment. At the same time, the speed control of the jet flame airflow is achieved by controlling the output power of the first plasma generator, and a laminar airflow can be formed by setting the position of the first plasma generator and the extended reaction section, so that the mixed carbon nanoparticles and iron nanoparticles move more smoothly in the extended reaction section to avoid blocking the reaction channel of the extended reaction section.

[0036] In addition, since the bottom electrode is grounded or connected to the power supply, during operation, the cathode of the second plasma generator forms a loop with the bottom electrode through the catalyst melting chamber. Since the voltage between the second plasma generator and the catalyst melting chamber is relatively large when the arc is started, if the bottom electrode is not grounded or connected to the power supply, it may cause damage to the equipment; in order to ensure the safety of the equipment, it is necessary to detect whether the bottom electrode is correctly grounded or connected to the power supply before starting the work. At the same time, during the operation, if the bottom electrode is connected to the power supply, the main circuit current can be monitored in real time by connecting a current sensor in series at the output end of the power supply. If the main circuit current approaches 0, the bottom electrode may be disconnected from the power supply, and it is necessary to stop working immediately to avoid damage to the equipment. If the bottom electrode is grounded, a high-voltage differential voltage sensor can be connected in parallel between the bottom electrode and the ground to measure the bottom electrode to ground voltage in real time. If the grounding is disconnected, the voltage detected by the sensor will rise to the open circuit voltage of the power supply. At this time, it is also necessary to stop working immediately to avoid damage to the equipment.

[0037] In addition, Figure 2 The illustrated embodiments are further described as follows: In this embodiment, the structure of the first plasma generator includes a carbon source gas delivery pipe arranged on the outer surface of the gun body, and the carbon source gas nozzle of the carbon source gas delivery pipe is arranged at the anode of the first plasma generator. The carbon source gas enters the carbon source gas delivery pipe through the carbon source gas inlet, and then sprays into the gas channel of the anode through the carbon source gas nozzle, so that the carbon source gas is cracked under the action of the cracking plasma flame to produce carbon nanoparticles. Since the temperature of the plasma generator is relatively high when it is working, in order to make it work longer, the first plasma generator is also provided with a first plasma generator anode cooling water inlet, a first plasma generator anode cooling water outlet, a first plasma generator anode cooling pipeline, a first plasma generator cathode cooling water inlet, a first plasma generator cathode cooling water outlet and a first plasma generator cathode cooling pipeline for realizing continuous cooling of the anode and cathode of the first plasma generator.

[0038] The structure of the second plasma generator also includes a second plasma generator cooling water outlet, a second plasma generator cooling water inlet and a second plasma generator cooling pipeline, which are used to cool the second plasma generator; it also includes a working gas inlet, that is, an argon gas inlet in this embodiment.

[0039] The structure of the powder delivery pipe includes a powder delivery pipe feed port for feeding. Since the air supply pipe is located in the high-temperature reaction chamber, in order to extend its service life, it also needs to be cooled. Therefore, it also includes a powder delivery pipe cooling water inlet, a powder delivery pipe cooling water outlet and a powder delivery pipe cooling pipeline.

[0040] The bottom electrode is in contact with the catalyst melting cavity and has good thermal conductivity due to its material properties. Therefore, the bottom electrode also needs to be cooled. Figure 2 As shown, the bottom electrode also includes a bottom electrode cooling water inlet, a bottom electrode cooling water outlet, and a bottom electrode cooling pipeline.

[0041] It should be noted that the specific structural composition of the above-mentioned first plasma generator, second plasma generator, powder feeding tube and bottom electrode is only one implementation method of the scheme of the present invention, and the change of the above-mentioned hardware structure does not affect the implementation of the scheme of the present invention; based on the core scheme of the present invention, appropriate above-mentioned equipment can be selected.

[0042] The above embodiment describes in detail the specific structure of the carbon nanotube preparation device and a brief description of the working method. In order to have a more detailed understanding of the method for preparing carbon nanotubes using the above device, Example 2 is described in detail below.

[0043] Example 2 This embodiment provides a method for preparing carbon nanotubes based on the carbon nanotube preparation device provided in Example 1, such as Figure 3 As shown, the method includes: In the cracking section of the reactor, the carbon source gas is cracked by the first plasma generator to produce carbon nanoparticles, and the carbon nanoparticles are blown to the vaporization section and the extended reaction section in turn; the carbon source gas can be methane, acetylene, etc. The activity of acetylene cracking is higher than that of methane, which can increase the growth rate by 2-3 times, but acetylene is difficult to store and has a high cost, so methane is often used as the carbon source gas. At the same time, methane as a carbon source gas will also produce hydrogen after cracking, which may play a role in inhibiting carbon deposition; hydrogen can be used as a reducing agent to help remove carbon deposits on the surface. The carbon nanoparticles produced here are driven by the airflow generated by the first plasma generator flame and pass through the vaporization section and the extended reaction section in turn.

[0044] In the vaporization section of the reactor, the molten iron in the catalyst melting cavity is vaporized by the second plasma generator to form iron atoms; wherein the molten iron in the catalyst melting cavity is mainly generated by iron powder fed through a powder feeding pipe. After the iron powder enters the reactor through the powder feeding pipe, it first passes through the arc zone between the second plasma generator and the catalyst melting cavity, and is liquefied under the action of the high temperature in the arc zone to form molten iron, which falls into the catalyst melting cavity. Through continuous heating by the arc, part of the molten iron is vaporized to form gaseous iron atoms, which float up and away from the arc zone. When the temperature drops, iron nanoparticles can be formed.

[0045] The carbon nanoparticles passing through the vaporization section are mixed with the iron atoms produced in the vaporization section and enter the extended reaction section. Since the iron atoms or the surface of the iron nanoparticles have high catalytic activity sites, the highly active carbon nanoparticles will be adsorbed on the surface of the iron nanoparticles and diffuse into the interior of the iron nanoparticles to form a carbon-iron solid solution; when the solubility of the carbon nanoparticles in the iron nanoparticles reaches saturation, the carbon atoms begin to precipitate from the surface of the iron particles, thereby producing carbon nanotubes. It can be understood that the size of the iron nanoparticles here is larger than that of the carbon nanoparticles, and the iron particles may not be nanometer-sized, but the larger the iron particles are, the lower the quality of the carbon nanotubes produced will be.

[0046] It should be further explained that the first plasma generator is a non-transferred arc generator, and the working gas introduced therein is a mixture of carbon source gas and argon gas, wherein the volume proportion of the carbon source gas is 5%-30%; the jet flame temperature of the first plasma generator is 1800-2500 degrees Celsius; and the temperature of the cracking section is higher than 1500 degrees Celsius. During operation, the temperature of the cracking section can be detected by the first temperature and pressure measuring device, and based on the temperature obtained by the detection, the power of the first plasma generator is adjusted so that the temperature of the cracking section is higher than 1500 degrees Celsius.

[0047] The second plasma generator is a transferred arc generator, which uses argon as the working gas. A plasma arc is formed between its cathode and the catalyst melting cavity. The iron powder entering the reactor through the powder feeding pipe falls into the catalyst melting cavity through the plasma arc to form molten iron. The molten iron is vaporized under high temperature to form iron atoms free in the vaporization section. The temperature inside the catalyst melting cavity is 2750-3000 degrees Celsius.

[0048] The temperature in the extension reaction section is 1000-1100 degrees Celsius; the temperature of the extension reaction section can be detected by a second temperature and pressure measuring device. If the temperature of the extension reaction section is not in the range of 1000-1100 degrees Celsius, the temperature in the extension reaction section is preferentially adjusted by adjusting the power of the second plasma generator.

[0049] Within a preset period, if the output of carbon nanotubes is less than a preset value, the carbon source gas input into the first plasma generator can be increased preferentially. If the unit output of carbon nanotubes does not increase significantly after the increase in the carbon source gas input, the iron powder input can be increased. The device and method provided by the present invention can determine the optimal ratio of the carbon source gas supply to the iron powder supply per unit time through experiments.

[0050] The method can control the generation rate of carbon nanoparticles and iron nanoparticles and the temperature of each area in the reaction furnace, thereby improving the controllability of the carbon nanotube production process and enabling continuous production of carbon nanotubes; the carbon nanotube carbon material prepared by the above method is as follows Figure 4 As shown in FIG. 1 , it is an electron microscope image of the carbon nanotube prepared by the method of the present invention. It can be seen from the image that it meets the requirements of single-walled carbon nanotubes and is a high-quality carbon nanomaterial. It can be seen that the method adopted by the present invention not only has corresponding breakthroughs in the controllability and continuity of production, but also has a higher performance advantage in production quality.

[0051] The produced carbon nanotubes pass through the outlet of the extended reaction section and enter the collection device, which can be a dry collection device or a wet collection device. Dry collection does not require a liquid medium and is suitable for continuous and large-scale production. The main methods include electrostatic collection, airflow classification collection, and mechanical scraping. Wet collection requires the use of a liquid medium to disperse and separate carbon nanotubes, which is suitable for small-batch, high-purity production scenarios; its main methods include liquid phase dispersion centrifugation, foam flotation, and electrophoretic deposition.

[0052] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A carbon material preparation device, comprising a reaction furnace, characterized in that: The reactor is provided with a first plasma generator, a second plasma generator, a catalyst melting cavity, and an extended reaction section; The first plasma generator is arranged on one side of the reaction furnace, and the extended reaction section is arranged on the other side of the reaction furnace opposite to the first plasma generator; the nozzle of the first plasma generator faces the extended reaction section; The second plasma generator is arranged at the upper part of the reaction furnace, the catalyst melting cavity is arranged at the bottom of the reaction furnace, and the nozzle of the second plasma generator is opposite to the catalyst melting cavity; The catalyst melting cavity is connected with a bottom electrode penetrating the bottom of the reaction furnace.

2. The carbon material preparation device according to claim 1, characterized in that: The first plasma generator is a non-transferred arc generator, and the nozzle of the first plasma generator is flush with the inner wall of the reaction furnace.

3. The carbon material preparation device according to claim 1, characterized in that: The second plasma generator is a transferred arc generator, which is fixed to the upper part of the reaction furnace through a first dynamic sealing flange group; the nozzle of the second plasma generator is 3-5 cm away from the catalyst melting cavity.

4. The carbon material preparation device according to claim 3, characterized in that: The catalyst melting chamber is embedded in the bottom of the reactor, and its opening is flush with the bottom of the reactor; the catalyst melting chamber is made of iron metal. When working, the bottom electrode is energized or grounded to generate an arc between the cathode of the second plasma generator.

5. The carbon material preparation device according to claim 4, characterized in that: It also includes a powder delivery pipe, which is arranged at the upper part of the reaction furnace, and the powder outlet of the powder delivery pipe is close to and directly faces the arc zone between the cathode of the second plasma generator and the catalyst melting cavity; the powder delivery pipe is also wrapped with a powder delivery pipe cooling water jacket.

6. The carbon material preparation device according to claim 1, characterized in that: It also includes an electrode connection port and a bottom electrode cooling water jacket wrapped around the bottom electrode, wherein the bottom electrode cooling water jacket is provided with a notch for connecting the electrode connection port with the bottom electrode; the bottom electrode is fixed to the bottom of the reactor through a second dynamic sealing flange group.

7. The carbon material preparation device according to claim 1, characterized in that: It also includes a first temperature and pressure measuring device and a second temperature and pressure measuring device. The first temperature and pressure measuring device is arranged in the reaction furnace, and the second temperature and pressure measuring device is arranged in the extended reaction section.

8. A method for preparing a carbon material, characterized in that: include: In the cracking section of the reaction furnace, the carbon source gas is cracked by a first plasma generator to produce carbon nanoparticles, and the carbon nanoparticles are blown to the vaporization section and the extended reaction section in sequence; In the vaporization section of the reaction furnace, the iron melt in the catalyst melting cavity is vaporized by a second plasma generator to form iron atoms; The carbon nanoparticles passing through the vaporization section are mixed with the iron atoms produced in the vaporization section and enter the extended reaction section to produce carbon materials.

9. The method for preparing a carbon material according to claim 8, characterized in that: The first plasma generator is a non-transferred arc generator, and the working gas introduced therein is a mixture of carbon source gas and argon gas, wherein the volume proportion of the carbon source gas is 5%-30%; the flame temperature of the first plasma generator is 1800-2500 degrees Celsius; the temperature of the cracking section is higher than 1500 degrees Celsius.

10. The method for preparing a carbon material according to claim 8, characterized in that: The second plasma generator is a transferred arc generator, which uses argon as the working gas. A plasma arc is formed between its cathode and the catalyst melting cavity. The iron powder entering the reactor through the powder feeding pipe falls into the catalyst melting cavity through the plasma arc to form molten iron. The molten iron is vaporized under high temperature to form iron atoms free in the vaporization section. The temperature inside the catalyst melting cavity is 2750-3000 degrees Celsius.

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