A method for preparing multi-walled carbon nanotubes
By preparing iron-cobalt composite catalysts through a sol-gel-calcination process and optimizing the CVD process, the problem of easy aggregation of catalyst active sites was solved, and efficient and low-cost industrial production of multi-walled carbon nanotubes was realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUIZHOU XICHENG NEW MATERIAL TECHNOLOGY CO LTD
- Filing Date
- 2026-03-02
- Publication Date
- 2026-06-09
AI Technical Summary
In existing technologies, the active sites of traditional iron-based and cobalt-based single-component or simple composite catalysts are prone to aggregation and have short catalytic lifetimes, resulting in low yields of multi-walled carbon nanotubes, which are difficult to meet the production demands of industrial applications.
Iron-cobalt composite catalysts were prepared using a sol-gel-calcination process. By mixing and calcining raw materials in a specific molar ratio, combined with CVD technology, the reaction temperature, gas flow rate and ratio were optimized to control the growth process of carbon nanotubes. Dehydrated and purified propylene was used as the carbon source, and nitrogen was used as the protective gas to ensure the activity of the catalyst and the purity of the product.
It significantly improved the yield of multi-walled carbon nanotubes by 85 times, far exceeding the level of less than 60 times in existing technologies, meeting the needs of industrial applications, reducing the cost of catalyst preparation, ensuring the purity and structural integrity of the product, and making it suitable for large-scale production.
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Figure CN122166767A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of carbon material preparation, and more particularly to a method for preparing multi-walled carbon nanotubes. Background Technology
[0002] Carbon nanotubes, with their unique one-dimensional tubular carbon nanostructure and excellent mechanical, electrical, and chemical stability, have shown broad application prospects in materials science, electronics, catalysis engineering, and other fields.
[0003] Currently, the main methods for synthesizing carbon nanotubes include arc discharge, laser evaporation, and chemical vapor deposition. Arc discharge and laser evaporation methods require extremely high reaction temperatures, making process control difficult, equipment costs high, and the products are prone to contamination with impurities such as amorphous carbon and carbon nanoparticles, making it difficult to achieve large-scale production. Chemical vapor deposition (CVD) has advantages such as lower reaction temperature, simpler process, less equipment investment, and stronger controllability of carbon nanotube growth parameters. It has gradually replaced arc discharge and laser evaporation methods and become the mainstream technology for the semi-industrial and industrial production of multi-walled carbon nanotubes.
[0004] In the process of preparing multi-walled carbon nanotubes by CVD, the size uniformity, activity stability and component synergy of catalyst particles are the core factors that determine the structure, morphology and performance of carbon nanotubes. In the existing technology, commonly used iron-based and cobalt-based single-component or simple composite catalysts have problems such as easy agglomeration of active sites and short catalytic lifetime, resulting in low yield of multi-walled carbon nanotubes, which is difficult to meet the production requirements of industrial applications.
[0005] Therefore, it is necessary to provide a method for preparing multi-walled carbon nanotubes to solve the above-mentioned technical problems. Summary of the Invention
[0006] This invention provides a method for preparing multi-walled carbon nanotubes, which solves the problems of low catalytic efficiency and insufficient yield of multi-walled carbon nanotubes in existing catalysts.
[0007] To address the aforementioned technical problems, this invention provides a method for preparing multi-walled carbon nanotubes, comprising the following steps: S1. Preparation of solution A: Add ammonium molybdate, citric acid monohydrate and pure water to a reactor equipped with a stirring device, and stir at room temperature until the solid is completely dissolved to obtain a homogeneous and transparent solution A. S2. Preparation of solution B: Add ferric nitrate, cobalt nitrate, magnesium nitrate and aluminum nitrate to solution A in sequence, heat to 80℃ and stir at a constant temperature for 1.5h to obtain sol-gel solution B; S3. Control the molar ratio of raw materials: In S1 and S2, the molar ratio of ammonium molybdate: citric acid monohydrate: ferric nitrate: cobalt nitrate: magnesium nitrate: aluminum nitrate: pure water is 2:10:12:9:8:6:1000; S4. Preparation of catalyst by calcination: Transfer solution B to a crucible, place it in a muffle furnace, heat it to 650℃ at a heating rate of 5-10℃ / min, calcine at a constant temperature for 1h, and obtain the iron-cobalt composite catalyst after natural cooling. S5. Heating and catalyst loading: Add 0.1g of the above-mentioned iron-cobalt composite catalyst into the quartz boat of the main reactor of the horizontal furnace, introduce nitrogen as a protective gas, and heat the horizontal furnace to 600-900℃ at a heating rate of 10-15℃ / min. S6. Carbon nanotube growth: Maintain reactor temperature at 600-900℃, adjust nitrogen flow rate to 100-350mL / min and propylene flow rate to 100-250mL / min. Propylene is cracked under the catalysis of iron-cobalt composite catalyst, and carbon species are deposited at the active sites of the catalyst and grow into multi-walled carbon nanotubes. S7. Product collection: After the reaction is complete, stop the flow of propylene and continue to flow nitrogen until the reactor cools to room temperature. Collect the black solid product in the quartz boat, which is the multi-walled carbon nanotube.
[0008] Preferably, the volume flow ratio of nitrogen to propylene in S6 is 1:1 to 2.5:1, and the propylene needs to be dehydrated and purified before being introduced to remove impurities and moisture, so as to avoid affecting the growth purity and morphology of carbon nanotubes.
[0009] Preferably, the reaction time in S6 is 30-80 min.
[0010] Preferably, the nitrogen gas is introduced for no less than 30 minutes after the reaction in S7 is completed, to ensure that the temperature inside the reactor drops to room temperature uniformly and to prevent the carbon nanotubes from oxidizing or deforming at high temperatures.
[0011] Preferably, the horizontal furnace used in S5 includes a furnace body, two bases, a furnace cover, and two support components; The two bases are symmetrically installed on both sides of the bottom of the furnace body; The furnace cover is located at one end of the furnace body; The two support components are respectively disposed on both sides of the furnace cover surface.
[0012] Preferably, the support assembly includes a mounting base, a telescopic bracket, and a fixing bolt. The mounting base is connected to the side of the furnace cover, and the telescopic bracket is connected to the bottom of the mounting base.
[0013] Preferably, the fixing bolt is disposed on the telescopic bracket.
[0014] Preferably, a movable component is provided between the two bases. The movable component includes two fixed rods, two movable sleeves, and a movable plate. The two movable sleeves are respectively fitted onto the surfaces of the two fixed rods, and the movable plate is connected between the two movable sleeves by a connecting block.
[0015] Preferably, both ends of the two fixing rods are connected to positioning seats, and the bottoms of the plurality of positioning seats are respectively connected to the surfaces of the two bases.
[0016] Preferably, a handle is connected to one side of the bottom of the movable plate, and an installation assembly is provided between the base and the positioning seat. The installation assembly includes an external threaded block, a mounting bracket and a threaded sleeve. The external threaded block is connected to the surface of the base, the mounting bracket is sleeved on the surface of the external threaded block and connected to the positioning seat, and the threaded sleeve is threadedly connected to the surface of the external threaded block.
[0017] Compared with related technologies, the method for preparing multi-walled carbon nanotubes provided by this invention has the following beneficial effects: This invention provides a method for preparing multi-walled carbon nanotubes. Through multi-component synergistic design, it effectively solves the problems of easy aggregation of active sites and short catalytic lifetime of traditional iron-based and cobalt-based single-component or simple composite catalysts, and significantly improves catalytic activity, so that the multi-walled carbon nanotubes can reach a maximum multiplication rate of 85 times, which is far higher than the level of less than 60 times in the prior art, and meets the production requirements of industrial applications. The catalyst is prepared using a sol-gel-calcination process, which is simple, mild, and has a clear molar ratio of each raw material, making it easy to scale up production. In addition, the raw material cost is controllable, which reduces the overall cost of catalyst preparation. The optimized CVD preparation process parameters, including propylene dehydration and purification treatment and nitrogen insulation and cooling after reaction, not only further improved the yield of multi-walled carbon nanotubes, but also ensured the purity and structural integrity of the product, avoiding the mixing of impurities and structural deformation. The overall process has advantages such as moderate reaction temperature, simple process, low equipment investment, and strong parameter controllability, which meet the actual needs of industrial production and can realize the efficient and low-cost preparation of multi-walled carbon nanotubes. Attached Figure Description
[0018] Figure 1 A schematic diagram of the structure of a first embodiment of a method for preparing multi-walled carbon nanotubes provided by the present invention; Figure 2 This is a schematic diagram of the structure of a second embodiment of a method for preparing multi-walled carbon nanotubes provided by the present invention; Figure 3 for Figure 2 The enlarged schematic diagram of part A shown below; Figure 4 A schematic diagram of the structure of a third embodiment of a method for preparing multi-walled carbon nanotubes provided by the present invention; Figure 5 for Figure 4 The enlarged schematic diagram of part B is shown.
[0019] The diagram is labeled: 1. Furnace body, 2. Base, 3. Furnace lid. 4. Support components; 41. Mounting base; 42. Telescopic bracket; 43. Fixing bolt. 5. Movable components, 51. Fixed rod, 52. Movable sleeve, 53. Movable plate, 6. Positioning seat; 7. Handle; 8. Mounting components, 81. External threaded block, 82. Mounting bracket, 83. Threaded sleeve. Detailed Implementation
[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0021] First Embodiment Please refer to the following: Figure 1 ,in, Figure 1 This is a schematic diagram of the structure of a first embodiment of a method for preparing multi-walled carbon nanotubes provided by the present invention. A method for preparing multi-walled carbon nanotubes includes the following steps:
[0022] S1. Preparation of solution A: Add ammonium molybdate, citric acid monohydrate and pure water to a reactor equipped with a stirring device, and stir at room temperature until the solid is completely dissolved to obtain a homogeneous and transparent solution A. S2. Preparation of solution B: Add ferric nitrate, cobalt nitrate, magnesium nitrate and aluminum nitrate to solution A in sequence, heat to 80℃ and stir at a constant temperature for 1.5h to obtain sol-gel solution B; S3. Control the molar ratio of raw materials: In S1 and S2, the molar ratio of ammonium molybdate: citric acid monohydrate: ferric nitrate: cobalt nitrate: magnesium nitrate: aluminum nitrate: pure water is 2:10:12:9:8:6:1000; S4. Preparation of catalyst by calcination: Transfer solution B to a crucible, place it in a muffle furnace, heat it to 650℃ at a heating rate of 5-10℃ / min, calcine at a constant temperature for 1h, and obtain the iron-cobalt composite catalyst after natural cooling. S5. Heating and catalyst loading: Add 0.1g of the above-mentioned iron-cobalt composite catalyst into the quartz boat of the main reactor of the horizontal furnace, introduce nitrogen as a protective gas, and heat the horizontal furnace to 600-900℃ at a heating rate of 10-15℃ / min. S6. Carbon nanotube growth: Maintain reactor temperature at 600-900℃, adjust nitrogen flow rate to 100-350mL / min and propylene flow rate to 100-250mL / min. Propylene is cracked under the catalysis of iron-cobalt composite catalyst, and carbon species are deposited at the active sites of the catalyst and grow into multi-walled carbon nanotubes. S7. Product collection: After the reaction is complete, stop the flow of propylene and continue to flow nitrogen until the reactor cools to room temperature. Collect the black solid product in the quartz boat, which is the multi-walled carbon nanotube.
[0023] The volumetric flow rate ratio of nitrogen to propylene in S6 is 1:1 to 2.5:1, and the propylene must be dehydrated and purified before being introduced to remove impurities and moisture, so as to avoid affecting the growth purity and morphology of carbon nanotubes.
[0024] The reaction time in S6 is 30-80 min.
[0025] After the reaction in S7 is completed, nitrogen gas is introduced for no less than 30 minutes to ensure that the temperature inside the reactor drops to room temperature uniformly and to prevent carbon nanotubes from oxidizing or deforming at high temperatures.
[0026] To verify the effectiveness of the method of the present invention, by controlling the reaction time variable, Examples 1-2 and Comparative Example 1 were set up. The specific experimental parameters and multi-walled carbon nanotube scaling ratios are shown in the table below: As shown in the table above, under the same reaction temperature (685℃) and propylene flow rate (100 mL / min), the yield of multi-walled carbon nanotubes significantly increased with increasing reaction time—the yield of Example 1 (reaction 60 min) (85 times) was significantly higher than that of Example 2 (reaction 40 min, 70 times) and Comparative Example 1 (reaction 20 min, 40 times), demonstrating that the iron-cobalt composite catalyst of the present invention has high catalytic activity, and the accompanying CVD process can effectively improve the yield of multi-walled carbon nanotubes. The working principle of the method for preparing multi-walled carbon nanotubes provided by this invention is as follows: First, an iron-cobalt composite catalyst was prepared using a sol-gel-calcination process with a specific molar ratio of raw materials. Ammonium molybdate was used as an auxiliary agent to inhibit the aggregation of active sites, citric acid monohydrate improved the dispersion uniformity of each component through complexation, and the support structure formed by magnesium nitrate and aluminum nitrate enhanced the stability of the catalyst. Together with the active components of iron nitrate and cobalt nitrate, a highly active and long-lived catalytic system was constructed. Subsequently, in the CVD process, nitrogen was used as a protective gas and propylene as a carbon source. Under optimized temperature, gas flow rate, and ratio conditions, propylene was efficiently cracked on the catalyst surface, and carbon species were directionally deposited and grown into multi-walled carbon nanotubes. The entire process was precisely controlled through process parameters to ensure product yield and quality.
[0027] Compared with related technologies, the method for preparing multi-walled carbon nanotubes provided by this invention has the following beneficial effects: This invention provides a method for preparing multi-walled carbon nanotubes. Through multi-component synergistic design, it effectively solves the problems of easy aggregation of active sites and short catalytic lifetime of traditional iron-based and cobalt-based single-component or simple composite catalysts, and significantly improves catalytic activity, so that the multi-walled carbon nanotubes can reach a maximum multiplication rate of 85 times, which is far higher than the level of less than 60 times in the prior art, and meets the production requirements of industrial applications. The catalyst is prepared using a sol-gel-calcination process, which is simple, mild, and has a clear molar ratio of each raw material, making it easy to scale up production. In addition, the raw material cost is controllable, which reduces the overall cost of catalyst preparation. The optimized CVD preparation process parameters, including propylene dehydration and purification treatment and nitrogen insulation and cooling after reaction, not only further improved the yield of multi-walled carbon nanotubes, but also ensured the purity and structural integrity of the product, avoiding the mixing of impurities and structural deformation. The overall process has advantages such as moderate reaction temperature, simple process, low equipment investment, and strong parameter controllability, which meet the actual needs of industrial production and can realize the efficient and low-cost preparation of multi-walled carbon nanotubes.
[0028] Second Embodiment Please refer to the following: Figure 2 and Figure 3 Based on the method for preparing multi-walled carbon nanotubes provided in the first embodiment of this application, the second embodiment of this application proposes another method for preparing multi-walled carbon nanotubes. The second embodiment is merely a preferred embodiment of the first embodiment, and the implementation of the second embodiment will not affect the separate implementation of the first embodiment.
[0029] Specifically, the second embodiment of this application provides a method for preparing multi-walled carbon nanotubes that differs in that the horizontal furnace used in S5 includes a furnace body 1, two bases 2, a furnace cover 3, and two support components 4. The two bases 2 are symmetrically installed on both sides of the bottom of the furnace body 1; The furnace cover 3 is disposed at one end of the furnace body 1; The two support components 4 are respectively disposed on both sides of the surface of the furnace cover 3.
[0030] The furnace cover 3 is used to seal the reactor, prevent gas leakage, and ensure the stability of the reaction atmosphere.
[0031] The support assembly 4 includes a mounting base 41, a telescopic bracket 42, and a fixing bolt 43. The mounting base 41 is connected to the side of the furnace cover 2, and the telescopic bracket 42 is connected to the bottom of the mounting base 41.
[0032] The support component 4 is used to provide support when the furnace cover 3 is opened, which facilitates operation. The telescopic bracket 42 can be adjusted in length by telescopic extension to adapt to different support requirements. The fixing bolt 43 is used to fix the length of the telescopic bracket 42 to ensure the stability of the support.
[0033] The fixing bolt 43 is disposed on the telescopic bracket 42.
[0034] A movable component 5 is provided between the two bases 2. The movable component 5 includes two fixed rods 51, two movable sleeves 52 and a movable plate 53. The two movable sleeves 52 are respectively fitted onto the surfaces of the two fixed rods 51, and the movable plate 53 is connected between the two movable sleeves 52 by a connecting block.
[0035] The movable plate 53 is used to place the quartz boat and related operating tools. Through the cooperation of the movable sleeve 52 and the fixed rod 51, the movable plate 53 can be moved horizontally, which makes it easy to send the quartz boat into or out of the furnace body 1.
[0036] Both ends of the two fixing rods 51 are connected to positioning seats 6, and the bottoms of the multiple positioning seats 6 are respectively connected to the surfaces of the two bases 2.
[0037] A handle 7 is connected to one side of the bottom of the movable plate 53.
[0038] The working principle of the method for preparing multi-walled carbon nanotubes provided by this invention is as follows: During catalyst loading and product collection, the movable plate 53 is pushed by the handle 7, causing the movable sleeve 52 to slide along the fixed rod 51, moving the movable plate 53 out of the furnace body 1 for easy placement or removal of the quartz boat containing the catalyst / product. After the operation is completed, the movable plate 53 is pushed back to ensure that the quartz boat is accurately positioned in the reaction area inside the furnace body 1. When opening the furnace cover 3, the length of the telescopic bracket 42 is adjusted to support it on the ground, and the length is fixed by the fixing bolt 43 to prevent the furnace cover 3 from tipping over and ensure operational safety. The base 2 and the positioning seat 6 together ensure the installation stability of the furnace body 1 and the movable components 5, providing reliable equipment support for the reaction process.
[0039] Compared with related technologies, the method for preparing multi-walled carbon nanotubes provided by this invention has the following beneficial effects: This invention provides a method for preparing multi-walled carbon nanotubes. By adding a support component 4 and a movable component 5, the filling of the quartz boat and the collection of products are made more convenient, effectively improving the operating efficiency. The support component 4 can stably support the furnace cover 3, avoiding the furnace cover 3 from tipping over and causing safety hazards during operation. The movable component 5, through its sliding design, enables the smooth transfer of the quartz boat, reducing the loss of catalyst or products during the transfer process, while ensuring the sealing of the reactor during operation, further improving the stability and yield of multi-walled carbon nanotube preparation.
[0040] Third Embodiment Please refer to the following: Figure 4 and Figure 5 Based on the method for preparing multi-walled carbon nanotubes provided in the first embodiment of this application, the third embodiment of this application proposes another method for preparing multi-walled carbon nanotubes. The third embodiment is merely a preferred embodiment of the first embodiment, and the implementation of the third embodiment will not affect the separate implementation of the first embodiment.
[0041] Specifically, the third embodiment of this application provides a method for preparing multi-walled carbon nanotubes that differs in that it further includes an installation component 8, which is disposed between the base 2 and the positioning seat 6. The installation component 8 includes an external threaded block 81, an installation bracket 82, and a threaded sleeve 83. The external threaded block 81 is connected to the surface of the base 2, the installation bracket 82 is sleeved on the surface of the external threaded block 81 and connected to the positioning seat 6, and the threaded sleeve 83 is threadedly connected to the surface of the external threaded block 81.
[0042] By tightening the threaded sleeve 83, the mounting bracket 82 can be tightly fixed to the external threaded block 81, thereby achieving a stable connection between the positioning seat 6 and the base 2; during disassembly, loosening the threaded sleeve 83 can separate the mounting bracket 82 from the external threaded block 81, making the operation simple.
[0043] The working principle of the method for preparing multi-walled carbon nanotubes provided by this invention is as follows: When installing the positioning seat 6, the mounting bracket 82 is fitted onto the surface of the external threaded block 81 on the base 2, ensuring that the mounting bracket 82 and the positioning seat 6 are tightly connected. Then, the threaded sleeve 83 on the surface of the external threaded block 81 is tightened, so that the threaded sleeve 83 presses against the mounting bracket 82, thereby fixing the positioning seat 6 to the base 2. When it is necessary to maintain or replace components such as the fixing rod 51 and the movable component 5, the threaded sleeve 83 is loosened, and the mounting bracket and the positioning seat 6 can be removed from the base 2 together. After the maintenance or replacement of the components is completed, the mounting and fixing can be reinstalled and fixed according to the above steps.
[0044] Compared with related technologies, the method for preparing multi-walled carbon nanotubes provided by this invention has the following beneficial effects: This invention provides a method for preparing multi-walled carbon nanotubes. By setting up an installation component 8, a detachable connection between the positioning seat 6 and the base 2 is achieved. Compared with the traditional fixed connection method, not only is the installation and disassembly operation more convenient, but the difficulty and cost of equipment maintenance are also reduced. At the same time, the threaded connection method can ensure the stability of the positioning seat 6 installation, avoid the positioning seat 6 from loosening due to equipment vibration during the reaction process, and thus ensure the stable operation of the movable component 5, providing a reliable equipment guarantee for the efficient preparation of multi-walled carbon nanotubes.
[0045] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A method for preparing multi-walled carbon nanotubes, characterized in that, Includes the following steps: S1. Preparation of solution A: Add ammonium molybdate, citric acid monohydrate and pure water to a reactor equipped with a stirring device, and stir at room temperature until the solid is completely dissolved to obtain a homogeneous and transparent solution A. S2. Preparation of solution B: Add ferric nitrate, cobalt nitrate, magnesium nitrate and aluminum nitrate to solution A in sequence, heat to 80℃ and stir at a constant temperature for 1.5h to obtain sol-gel solution B; S3. Control the molar ratio of raw materials: In S1 and S2, the molar ratio of ammonium molybdate: citric acid monohydrate: ferric nitrate: cobalt nitrate: magnesium nitrate: aluminum nitrate: pure water is 2:10:12:9:8:6:1000; S4. Preparation of catalyst by calcination: Transfer solution B to a crucible, place it in a muffle furnace, heat it to 650℃ at a heating rate of 5-10℃ / min, calcine at a constant temperature for 1h, and obtain the iron-cobalt composite catalyst after natural cooling. S5. Heating and catalyst loading: Add 0.1g of the above-mentioned iron-cobalt composite catalyst into the quartz boat of the main reactor of the horizontal furnace, introduce nitrogen as a protective gas, and heat the horizontal furnace to 600-900℃ at a heating rate of 10-15℃ / min. S6. Carbon nanotube growth: Maintain reactor temperature at 600-900℃, adjust nitrogen flow rate to 100-350mL / min and propylene flow rate to 100-250mL / min. Propylene is cracked under the catalysis of iron-cobalt composite catalyst, and carbon species are deposited at the active sites of the catalyst and grow into multi-walled carbon nanotubes. S7. Product collection: After the reaction is complete, stop the flow of propylene and continue to flow nitrogen until the reactor cools to room temperature. Collect the black solid product in the quartz boat, which is the multi-walled carbon nanotube.
2. The method for preparing multi-walled carbon nanotubes according to claim 1, characterized in that, The volumetric flow rate ratio of nitrogen to propylene in S6 is 1:1 to 2.5:1, and the propylene must be dehydrated and purified before being introduced to remove impurities and moisture, so as to avoid affecting the growth purity and morphology of carbon nanotubes.
3. The method for preparing multi-walled carbon nanotubes according to claim 1, characterized in that, The reaction time in S6 is 30-80 min.
4. The method for preparing multi-walled carbon nanotubes according to claim 1, characterized in that, After the reaction in S7 is completed, nitrogen gas is introduced for no less than 30 minutes to ensure that the temperature inside the reactor drops to room temperature uniformly and to prevent carbon nanotubes from oxidizing or deforming at high temperatures.
5. The method for preparing multi-walled carbon nanotubes according to claim 1, characterized in that, The horizontal furnace used in S5 includes a furnace body, two bases, a furnace cover, and two support components. The two bases are symmetrically installed on both sides of the bottom of the furnace body; The furnace cover is located at one end of the furnace body; The two support components are respectively disposed on both sides of the furnace cover surface.
6. The method for preparing multi-walled carbon nanotubes according to claim 4, characterized in that, The support assembly includes a mounting base, a telescopic bracket, and a fixing bolt. The mounting base is connected to the side of the furnace cover, and the telescopic bracket is connected to the bottom of the mounting base.
7. The method for preparing multi-walled carbon nanotubes according to claim 5, characterized in that, The fixing bolt is installed on the telescopic bracket.
8. The method for preparing multi-walled carbon nanotubes according to claim 4, characterized in that, A movable component is provided between the two bases. The movable component includes two fixed rods, two movable sleeves, and a movable plate. The two movable sleeves are respectively fitted onto the surfaces of the two fixed rods, and the movable plate is connected between the two movable sleeves by a connecting block.
9. The method for preparing multi-walled carbon nanotubes according to claim 8, characterized in that, Both ends of the two fixing rods are connected to positioning seats, and the bottoms of the multiple positioning seats are respectively connected to the surfaces of the two bases.
10. The method for preparing multi-walled carbon nanotubes according to claim 8, characterized in that, A handle is connected to one side of the bottom of the movable plate. An installation assembly is provided between the base and the positioning seat. The installation assembly includes an external threaded block, a mounting bracket, and a threaded sleeve. The external threaded block is connected to the surface of the base. The mounting bracket is sleeved on the surface of the external threaded block and connected to the positioning seat. The threaded sleeve is threadedly connected to the surface of the external threaded block.