Carbon material preparation device and preparation method

Abstract

The present invention belongs to the technical field of carbon nanomaterial preparation, and relates to a carbon material preparation device and a preparation method. The device specifically includes: a reaction furnace, on which a first plasma generator, a second plasma generator, a catalyst melting cavity, and an extended reaction section are provided; 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 on the upper part of the reaction furnace, the catalyst melting cavity is arranged at the bottom inside 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 through the bottom of the reaction furnace. This device enables the yields of carbon nanoparticles and iron nanoparticles to be controllable respectively, and can achieve the optimal production speed by adjusting the two sets of plasma generators separately.

Description

Technical Field

[0001] The present 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] Due to the diversity of its structure, carbon materials are widely used in the fields of energy, electronics, environmental protection, and medicine. In particular, carbon nanotubes (CNTs), as a new material with a unique one-dimensional nanostructure and excellent physical and chemical properties, have received extensive 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 the fields of composite materials, electronic devices, energy storage (such as lithium-ion batteries and supercapacitors), catalyst carriers, etc. However, the large-scale production and commercial application of carbon nanotubes still face many technical bottlenecks, especially problems such as the efficiency and controllability of the production process, the optimization of equipment design, and the control of production costs.

[0003] Currently, the industrial production of carbon materials such as carbon nanotubes mainly relies on chemical vapor deposition (CVD). Its basic principle is that carbon source gases (such as methane, ethylene, etc.) are cracked on the surface of a catalyst (such as transition metals iron, cobalt, nickel, or their alloys), generating carbon atoms and self-assembling to form a nanotube structure. The catalysts used in existing carbon nanotube production devices mostly adopt iron oxides, whose catalytic rate is not as good as that of iron atoms or iron nanoparticles, but the preparation of iron atoms or iron nanoparticles is relatively difficult, and their high chemical activity makes them difficult to preserve; in addition, when using plasma-assisted CVD for production, a single plasma generator is used to generate high temperature to crack the carbon source gas and vaporize the iron-based catalyst in the same area, and it is 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 to solve the problems of difficult direct use of iron atoms or iron nanoparticles as catalysts and difficult control of the output of carbon materials; the specific solutions are as follows:

[0005] In the first aspect, a carbon material preparation device is provided, including a reaction furnace, and a first plasma generator, a second plasma generator, a catalyst melting cavity, and an extended reaction section are arranged on the reaction furnace;

[0006] The first plasma generator is a non-transferred arc generator, which 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;

[0007] The second plasma generator is a transferred arc generator, which is arranged at the upper part of the reaction furnace. The catalyst melting cavity is arranged at the inner bottom of the reaction furnace, and the nozzle of the second plasma generator faces the catalyst melting cavity.

[0008] The catalyst melting cavity is connected with a bottom electrode penetrating through the bottom of the reaction furnace.

[0009] Furthermore, the nozzle of the first plasma generator is flush with the inner wall of the reaction furnace.

[0010] Furthermore, the second plasma generator is fixed at the upper part of the reaction furnace through a first dynamic seal flange group; the distance between the nozzle of the second plasma generator and the catalyst melting cavity is 3-5 cm.

[0011] Furthermore, the catalyst melting cavity is embedded in the inner bottom of the reaction furnace, and its opening is flush with the inner bottom of the reaction furnace; the catalyst melting cavity is made of iron metal. During operation, an electric arc is generated between the bottom electrode through power-on or grounding and the cathode of the second plasma generator.

[0012] Furthermore, it further includes a powder feeding pipe. The powder feeding pipe is arranged at the upper part of the reaction furnace, and the powder outlet of the powder feeding pipe is close to and faces the arc region between the cathode of the second plasma generator and the catalyst melting cavity; the powder feeding pipe is also wrapped with a powder feeding pipe cooling water jacket.

[0013] Furthermore, it further includes an electrode connection port and a bottom electrode cooling water jacket wrapped on the bottom electrode. The bottom electrode cooling water jacket is provided with a notch for connecting the electrode connection port and the bottom electrode; the bottom electrode is fixed at the bottom of the reaction furnace through a second dynamic seal flange group.

[0014] Furthermore, it further 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.

[0015] In a second aspect, a method for preparing carbon materials is provided. The method includes:

[0016] Cracking a carbon source gas through a first plasma generator in the cracking section of the reaction furnace to generate carbon nanoparticles, and blowing the carbon nanoparticles to the vaporization section and the extended reaction section in sequence;

[0017] Vaporizing the iron molten liquid in the catalyst melting cavity through a second plasma generator in the vaporization section of the reaction furnace to form iron atoms;

[0018] The carbon nanoparticles passing through the vaporization section are mixed with the iron atoms generated in the vaporization section and enter the extended reaction section to produce carbon materials.

[0019] Further, the first plasma generator is a non-transferred arc generator, and the working gas introduced into it is a mixed gas of a carbon source gas and argon, where 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.

[0020] Further, the second plasma generator is a transferred arc generator, with argon as the working gas. A plasma arc is formed between its cathode and the catalyst melting cavity. The iron powder entering the reaction furnace through the powder feeding pipe falls into the catalyst melting cavity through the plasma arc to form molten iron. The molten iron vaporizes under high temperature to form iron atoms free in the vaporization section; the temperature in the catalyst melting cavity is 2750 - 3000 degrees Celsius.

[0021] Beneficial effects:

[0022] Through the device and method provided by the present invention, the vaporization of molten iron and the cracking of the carbon source gas are 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 yields of carbon nanoparticles and iron nanoparticles can be controlled separately, and the optimal production speed can be achieved by adjustment. At the same time, the speed of the flame jet is controlled by controlling the output power of the first plasma generator, and through the position setting of the first plasma generator and the extended reaction section, a laminar air flow can be formed, making the mixed carbon nanoparticles and iron nanoparticles move more smoothly in the extended reaction section and avoiding blocking the reaction channels in the extended reaction section. Description of the Drawings

[0023] Figure 1 is a carbon material production device adopted in the prior art;

[0024] Figure 2 is a carbon material production device provided by the present invention;

[0025] Figure 3 is the carbon material production method provided by the present invention;

[0026] Figure 4 is an electron microscope image of single-walled carbon nanotubes produced by the carbon material production device provided by the present invention.

[0027] Reference numerals: 1. First temperature and pressure measuring device, 2. Pyrolysis plasma flame, 3. Carbon source gas nozzle, 4. Carbon source gas delivery pipe, 5. Anode cooling water inlet of the first plasma generator, 6. Anode cooling water outlet of the first plasma generator, 7. Carbon source gas inlet, 8. Cathode cooling water inlet of the first plasma generator, 9. Cathode cooling water outlet of the first plasma generator, 10. First plasma generator, 11. Thermal insulation layer, 12. Second plasma generator cooling water outlet, 13. Second plasma generator cooling water inlet, 14. Argon inlet, 15. Second plasma generator, 16. First dynamic seal flange group, 17. Feed inlet of the powder delivery pipe, 18. Cooling water inlet of the powder delivery pipe, 19. Cooling water outlet of the powder delivery pipe, 20. Powder delivery pipe, 21. Bottom electrode, 22. Electrode connection port, 23. Bottom electrode cooling water inlet, 24. Bottom electrode cooling water outlet, 25. Second dynamic seal flange group, 26. Catalyst melting cavity, 27. Transfer arc column, 28. Initial reaction region for carbon material formation, 29. Outlet of the extended reaction section, 30. Extended reaction section, 31. Tube furnace body of the extended reaction section, 32. Second temperature and pressure measuring device, 33. Pyrolysis gas, 34. Mixed gas. Detailed implementation manners

[0028] To make the objectives, 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 with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0029] 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 description of the implementation manners will be based on carbon nanotubes as an example. As Figure 1 shown, in the existing device for preparing carbon nanotubes by using a plasma generator-assisted CVD method, a single non-transfer arc plasma generator is used to maintain a high-temperature reaction environment in the reaction furnace, so that the introduced carbon source gas is pyrolyzed to form carbon nano-particles or carbon black, and the iron compound on the carrier is used as a catalyst for the growth of carbon nanotubes. This device uses a single plasma generator to maintain a high-temperature reaction environment, so that the pyrolyzed carbon source gas and the catalyst are in the same region, resulting in unstable quality of the produced carbon nanotubes. In addition, the quality of the iron compound is fixed and cannot be continuously increased, so that the amount of carbon nanotubes that can be produced is limited, and only the intake of the carbon source gas can be controlled, and the control of the growth rate of 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 be applied in industrial production scenarios.

[0030] Based on the problems of the above-mentioned prior art, the present invention aims to provide a new device and preparation method for preparing carbon nanotubes by using a plasma generator to assist the CVD method; it is expected to solve the problems of difficult direct use of iron atoms or iron nanoparticles as catalysts and difficult control of the yield of iron nanotubes.

[0031] Example 1

[0032] This example mainly illustrates the structure and working principle of the carbon nanotube preparation device provided by the present invention, as Figure 2 shown, which includes a reaction furnace, on which a first plasma generator, a second plasma generator, a catalyst melting cavity, and an extended reaction section are provided; 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. At the same time, in order to reduce energy consumption, the reaction furnace and the extended reaction section are also wrapped with a heat insulation layer.

[0033] Among them, 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, as Figure 2 shown, if the first plasma generator is arranged on the right side of the reaction furnace, then the extended reaction section is arranged on the left side of the reaction furnace; the cross-section (perpendicular to the axis of the reaction channel) of the reaction channel of the extended reaction section can be rectangular or circular, preferably circular, which is convenient for cleaning, and the produced carbon nanotubes can move more smoothly to the outlet of the extended reaction section.

[0034] In one implementation, the first plasma generator is arranged near the bottom of the reaction furnace on one side (such as Figure 2 the right side shown), and there is a certain height difference between the bottom of the reaction furnace and the reaction channel of the extended reaction section, and a slope is provided at the connection to guide the gas flow into the extended reaction section; the height difference is about 3 - 8 cm, and the setting of the slope can avoid the formation of turbulence at the connection, so that the produced carbon nanotubes are not easily discharged from the extended reaction section and cause blockage.

[0035] The second plasma generator is arranged at the upper part of the reaction furnace, and the catalyst melting cavity is arranged at the inner bottom of the reaction furnace, and the nozzle of the second plasma generator is opposite to the catalyst melting cavity; as Figure 2 shown, in one implementation, the nozzle of the second plasma generator is 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 area of the reaction furnace where the catalyst melting cavity is located is defined as the vaporization section, and the area between the first plasma generator and the catalyst melting cavity is defined as the cracking section.

[0036] In one embodiment, the nozzle directions of the first plasma generator and the second plasma generator are in the same plane and perpendicular to each other.

[0037] The catalyst melting cavity is connected to a bottom electrode that penetrates the bottom of the reaction furnace. During use, the bottom electrode is grounded or connected to a power source.

[0038] In one embodiment, the extended reaction section is integrally provided with the reaction furnace, which has a better heat preservation effect; however, it is not conducive to maintenance; therefore, another possible embodiment is as Figure 2 shown, the extended reaction section is connected to the reaction furnace through a flange.

[0039] To understand the working mode of the present invention more clearly, the following further description is made. The first plasma generator is a non-transferred arc generator. To extend its service life, independent water-cooling channels are provided for both its anode and cathode; and to avoid the influence of the high temperature in the reaction furnace, it is a preferred embodiment that the nozzle of the first plasma generator is flush with the inner wall of the reaction furnace.

[0040] The catalyst melting cavity is embedded in the inner bottom of the reaction furnace, and its opening is flush with the inner bottom of the reaction furnace; the catalyst melting cavity is made of iron metal, that is, the catalyst melting cavity can be understood as an iron dry pot with an inner cavity. During operation, by connecting the bottom electrode to a power source or grounding, an arc is generated between the bottom electrode and the cathode of the second plasma generator.

[0041] Since a high-temperature arc needs to be generated between the second plasma generator and the catalyst melting cavity, the second plasma generator should be a transferred arc generator, which is fixed to the upper part of the reaction furnace through the first dynamic seal flange group; the distance between the nozzle of the second plasma generator and the inner wall of the catalyst melting cavity is generally 3-5 cm, and this distance facilitates the transfer arc column to hit the inner wall of the catalyst melting cavity; and the second plasma generator and the vaporization section where the catalyst melting cavity is located are close to the extended reaction section.

[0042] Based on the positional relationship between the first plasma generator, the second plasma generator, and the extended reaction section in the reaction furnace, it can be determined that the first plasma generator can achieve the cracking of the carbon source gas to produce carbon nanoparticles in the cracking section. The high-temperature arc generated between the second plasma generator in the vaporization section and the catalyst melting cavity can liquefy iron powder to obtain molten iron liquid, and vaporize the molten iron liquid at a certain controllable rate (achieved by adjusting the power of the second plasma generator) to produce gaseous iron atoms or iron particles (since when the vaporized iron atoms float away from the high-temperature arc generated between the second plasma generator and the catalyst melting cavity in the vaporization section, they will solidify into iron particles due to the temperature decrease). The carbon nanoparticles flow towards the vaporization section through the airflow generated by the flame of the first plasma generator. After mixing with iron atoms or iron particles in the vaporization section, they enter the extended reaction section along with the airflow. In the extended reaction section, the carbon nanoparticles use the iron particles as catalysts and grow carbon nanotubes on their surfaces; 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.

[0043] Since continuous production needs to be achieved, the present invention does not adopt the method of pre-placing iron-based compounds such as iron powder in the catalyst melting cavity. The purpose of setting the second plasma generator is to controllably vaporize the molten iron liquid. Although the catalyst melting cavity is made of metallic iron (which can avoid generating other impurities during the reaction), in order to avoid its excessive consumption, a powder feeding pipe for adding iron powder in real time needs to be set.

[0044] Specifically, the powder feeding pipe is set at the upper part of the reaction furnace, and its powder outlet is close to and directly faces the arc area between the cathode of the second plasma generator and the catalyst melting cavity; through the setting of the powder feeding pipe, the amount of iron powder fed can be adjusted in real time according to the production of carbon nanotubes and other situations. Since the part of the powder feeding pipe with the discharge port penetrates through the reaction furnace 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; used to cool the powder feeding pipe.

[0045] Since a large current passes through the bottom electrode during the operation of the device, and the heat in the catalyst melting cavity will also conduct to the bottom electrode; therefore, the bottom electrode is also wrapped with a bottom electrode cooling water jacket; the bottom electrode cooling water jacket is provided with a notch for connecting the electrode connection port to the bottom electrode. The electrode connection port is a connector for connecting the power electrode to the bottom electrode, and its setting facilitates the plugging and unplugging of the power electrode, so as to facilitate equipment maintenance and handling; since the inside of the reaction furnace is in a high-temperature and high-pressure state, in order to ensure the sealing performance, the bottom electrode is fixed to the bottom of the reaction furnace through the second dynamic sealing flange group.

[0046] When the device of the present invention is used to produce carbon nanotubes, the amounts of carbon source gas, iron powder, and the powers of the first plasma generator and the second plasma generator are all controllable. Therefore, the controllability is relatively strong during the production of carbon nanotubes. In order to form relevant control bases, especially for the control bases of the powers 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. Among them, the first temperature and pressure measuring device is arranged in the cracking section of the reaction furnace, and the second temperature and pressure measuring device is arranged in the extended reaction section.

[0047] The above device structure enables the vaporization of the molten iron and the cracking of the carbon source gas to be carried out separately. The first plasma generator is mainly used to crack the carbon source gas to generate carbon nano-particles, and the second plasma generator is mainly used to vaporize the molten iron to generate iron atoms or iron nano-particles; this design can make the yields of carbon nano-particles and iron nano-particles controllable respectively, and can be adjusted to achieve the optimal production speed. At the same time, the speed control of the flame jet gas flow is realized by controlling the output power of the first plasma generator, and through the position setting of the first plasma generator and the extended reaction section, a laminar gas flow can be formed, so that the mixed carbon nano-particles and iron nano-particles move more smoothly in the extended reaction section, avoiding blocking the reaction channel of the extended reaction section.

[0048] 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 circuit with the bottom electrode through the catalyst melting cavity. Since the voltage during arcing between the second plasma generator and the catalyst melting cavity is relatively large, if the bottom electrode is not grounded or not 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 work. At the same time, during the operation process, 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 power output end. If the main circuit current approaches 0, it may indicate that the bottom electrode is disconnected from the power supply, and the work needs to be stopped immediately to avoid equipment damage. 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 voltage of the bottom electrode to the ground 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, and the work also needs to be stopped immediately to avoid equipment damage.

[0049] In addition, regarding Figure 2 the embodiments shown are further described as follows:

[0050] In this embodiment, the structural composition of the first plasma generator includes a carbon source gas delivery pipe arranged on the outer surface of the gun body. 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 is sprayed into the gas channel of the anode through the carbon source gas nozzle. Thus, the carbon source gas is cracked under the action of the cracking plasma flame to generate carbon nanoparticles. Since the temperature is relatively high when the plasma generator is working, in order to make its working duration 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 to continuously cool the anode and cathode of the first plasma generator.

[0051] The structural composition of the second plasma generator further includes a second plasma generator cooling water outlet, a second plasma generator cooling water inlet, and a second plasma generator cooling pipeline to cool down the second plasma generator; it also includes a working gas inlet, i.e., the argon inlet in this embodiment.

[0052] The structural composition of the powder feeding pipe includes a powder feeding pipe inlet for feeding. Since part of 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 down. Therefore, it also includes a powder feeding pipe cooling water inlet, a powder feeding pipe cooling water outlet, and a powder feeding pipe cooling pipeline.

[0053] Since the bottom electrode is in contact connection with the catalyst melting cavity and has good heat conduction performance due to its material characteristics, it also needs to be cooled for the bottom electrode. Therefore, as Figure 2 shown, the bottom electrode also includes a bottom electrode cooling water inlet, a bottom electrode cooling water outlet, and a bottom electrode cooling pipeline.

[0054] It should be noted that the specific structural compositions of the above-mentioned first plasma generator, second plasma generator, powder feeding pipe, and bottom electrode are only one implementation manner to realize the solution of the present invention. The change of the above-mentioned hardware structure does not affect the realization of the solution of the present invention; based on the core solution of the present invention, appropriate above-mentioned devices can be selected.

[0055] The specific structure of the carbon nanotube preparation device and a brief description of the working method are detailed in the above-mentioned embodiment. In order to understand in more detail the method of preparing carbon nanotubes using the above-mentioned device, the following will be described in detail through Embodiment 2.

[0056] Embodiment 2

[0057] This embodiment provides a carbon nanotube preparation method based on the carbon nanotube preparation device provided in Embodiment 1. As Figure 3As shown, the method includes:

[0058] In the cracking section of the reaction furnace, a carbon source gas is cracked by a first plasma generator to generate carbon nanoparticles, and the carbon nanoparticles are blown successively towards the vaporization section and the extended reaction section; the carbon source gas can be methane, acetylene, etc. The cracking activity of acetylene is higher than that of methane, which can increase the growth rate by 2-3 times. However, the storage of acetylene is difficult and the cost is high. Therefore, methane is mostly used as the carbon source gas. At the same time, when methane is used as the carbon source gas, hydrogen will also be generated after cracking, which may play a role in inhibiting carbon deposition; hydrogen can be used as a reducing agent to help remove surface carbon deposition. The carbon nanoparticles generated here pass successively through the vaporization section and the extended reaction section under the drive of the gas flow generated by the flame of the first plasma generator.

[0059] In the vaporization section of the reaction furnace, iron atoms are vaporized from the molten iron in the catalyst melting cavity by a second plasma generator; among them, the molten iron in the catalyst melting cavity is mainly generated by iron powder fed through a powder feeding tube. After the iron powder enters the reaction furnace through the powder feeding tube, it first passes through the arc region between the second plasma generator and the catalyst melting cavity. Under the action of the high temperature in the arc region, it is liquefied to form molten iron and falls into the catalyst melting cavity. Through continuous heating by the arc, part of the molten iron is vaporized to form gaseous iron atoms. The gaseous iron atoms floating away from the arc region can form iron nanoparticles when the temperature drops.

[0060] The carbon nanoparticles passing through the vaporization section are mixed with the iron atoms generated in the vaporization section and enter the extended reaction section. Since the surface of the iron atoms or iron nanoparticles has high catalytic active sites, the highly active carbon nanoparticles will adsorb 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, carbon atoms begin to precipitate from the surface of the iron particles, and then carbon nanotubes are generated. 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 nanoscale, but the larger the iron particles, the lower the quality of the carbon nanotubes produced.

[0061] Further, it should be noted that the first plasma generator is a non-transferred arc generator, and the working gas introduced into it is a mixed gas of a carbon source gas and argon, where the volume ratio 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. During operation, the temperature of the cracking section can be detected by a first temperature and pressure measuring device, and based on the detected temperature, the power of the first plasma generator can be adjusted so that the temperature of the cracking section is higher than 1500 degrees Celsius.

[0062] The second plasma generator is a transferred arc generator, with argon as the working gas. A plasma arc is formed between its cathode and the catalyst melting cavity. The iron powder entering the reaction furnace through the powder feeding pipe falls into the catalyst melting cavity through the plasma arc to form molten iron liquid. The molten iron liquid vaporizes under high temperature to form iron atoms free in the vaporization section; the temperature in the catalyst melting cavity is 2750 - 3000 degrees Celsius.

[0063] The temperature in the extended reaction section is 1000 - 1100 degrees Celsius; the temperature condition of the extended reaction section can be detected by the second temperature and pressure measuring device. If the temperature in the extended reaction section is not in the range of 1000 - 1100 degrees Celsius, the temperature in the extended reaction section is preferably adjusted by adjusting the power of the second plasma generator.

[0064] Within a preset period, if the output of carbon nanotubes is less than the preset value, the carbon source gas input amount of the first plasma generator can be preferentially increased. If there is no obvious increase in the unit output of carbon nanotubes after the increase of the carbon source gas input amount, the feeding amount of iron powder is increased. Through the device and method provided by the present invention, the ratio of the optimal carbon source gas supply amount to the iron powder supply amount per unit time can be determined through experiments.

[0065] This method can control the generation rates of carbon nanoparticles and iron nanoparticles and the temperatures in each area of the reaction furnace, thereby improving the controllability in the production process of carbon nanotubes and enabling continuous production of carbon nanotubes; the carbon nanotube carbon material prepared by the above method is as Figure 4 shown. It is the electron microscope image of the carbon nanotubes prepared based on the method of the present invention. As can be seen from the figure, it meets the requirements of single-walled carbon nanotubes and belongs to high-quality carbon nanomaterials. 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 high performance advantages in terms of production quality.

[0066] The produced carbon nanotubes enter the collection device after passing through the outlet of the extended reaction section. The collection device 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 method, air flow classification collection method, mechanical scraping method, etc. Wet collection requires a liquid medium to disperse and separate carbon nanotubes and is suitable for small-batch and high-purity production scenarios; the main methods include liquid-phase dispersion centrifugation method, foam flotation method, electrophoresis deposition method, etc.

[0067] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within 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 a non-transferred arc generator, which 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 a transferred arc generator, which 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 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 fixed to the upper part of the reaction furnace through the 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.

Images