A method for preparing a catalyst for synthesizing carbon nanotubes

Abstract

The application provides a preparation method of a catalyst for synthesizing carbon nanotubes. The preparation method of the catalyst for synthesizing carbon nanotubes comprises the following steps: S1, metal salt dissolution, mixing an active metal salt, a carrier metal salt, an auxiliary metal salt and deionized water in a reaction kettle according to a preset proportion, and stirring to obtain a metal salt solution after preliminary dissolution. The preparation method of the catalyst for synthesizing carbon nanotubes provided by the application can realize uniform dispersion of active components, strengthen the synergistic effect between the carrier and the active components, and catalyze the synthesis of multi-walled carbon nanotubes with complete structure, high purity, excellent electrochemical performance, low resistivity (63 mΩ·cm), outstanding conductivity, and excellent thermal stability (the fastest weight loss rate temperature can reach 705 DEG C). The application solves the problem that the electrochemical performance and thermal stability of carbon nanotubes are difficult to balance, and is suitable for high-end application scenarios such as conductive materials, energy storage devices, high-performance composite materials and the like.

Description

Technical Field

[0001] This invention relates to the field of carbon nanotube catalyst preparation technology, and more particularly to a method for preparing a catalyst for synthesizing carbon nanotubes. Background Technology

[0002] Carbon nanotubes are one-dimensional nanotube materials formed by carbon atoms with sp² hybridization. They have a hollow coaxial tubular structure with diameters typically in the nanometer range and lengths ranging from micrometers to millimeters. They possess excellent electrical, mechanical, and thermal properties, exhibiting conductivity comparable to metals, high strength, and good thermal stability. Based on the number of wall layers, they can be classified into single-walled and multi-walled carbon nanotubes. They are widely used in conductive materials, energy storage devices, composite materials, catalyst supports, and other fields, making them a novel nanomaterial with significant application value.

[0003] The preparation of catalysts for synthesizing carbon nanotubes refers to the process of obtaining highly dispersed nanoscale catalytic particles by using transition metals such as iron, cobalt, and nickel as active components, combined with supports and additives, through liquid-phase synthesis, loading, heat treatment, and reduction. Typically, metal salts are first prepared into solutions and then loaded onto supports such as magnesium oxide and aluminum oxide using co-precipitation, sol-gel, or impregnation methods. After drying and calcination to remove impurities and organic matter, a precursor is formed. Then, it is reduced under a hydrogen atmosphere to obtain metal nanocatalysts with controllable particle sizes of 5–20 nm and uniform dispersion. The core is to precisely control the particle size, morphology, and dispersibility to determine the diameter, wall number, purity, and structural regularity of carbon nanotubes.

[0004] Existing catalysts for synthesizing carbon nanotubes are cumbersome to prepare, often employing methods such as sol-gel and co-precipitation, requiring multiple steps including precipitation, filtration, and drying. These methods are demanding, energy-intensive, and costly, and exhibit poor batch stability, making industrial-scale production difficult. Furthermore, the uneven dispersion of the active components in the catalyst and the weak synergy between the support and the active components make it difficult to achieve both high conductivity and thermal stability of carbon nanotubes, thus limiting their application in high-end fields such as conductive materials, energy storage devices, and high-performance composite materials.

[0005] Therefore, it is necessary to provide a method for preparing catalysts for the synthesis of carbon nanotubes to solve the above-mentioned technical problems. Summary of the Invention

[0006] This invention provides a method for preparing a catalyst for synthesizing carbon nanotubes, which solves the problems of existing carbon nanotube catalyst preparation processes being cumbersome, requiring harsh conditions, costing high, having poor stability, and exhibiting uneven dispersion of active components, thus limiting the performance of carbon nanotubes and making them difficult to use in high-end fields.

[0007] To solve the above-mentioned technical problems, the present invention provides a method for preparing a catalyst for synthesizing carbon nanotubes, comprising the following steps: S1: Metal salt dissolution: According to the preset ratio, the active metal salt, carrier metal salt, auxiliary metal salt and deionized water are mixed in the reaction vessel and stirred until initially dissolved to obtain a metal salt solution; S2: Complexing agent mixing: Add complexing agent to metal salt solution and continue stirring until completely dissolved to obtain mixed solution; S3: Constant temperature complexation and maturation. Place the mixed solution in an environment of 60-90℃ and stir continuously for 1-3 hours to ensure that the raw materials are fully complexed and uniform. S4: High-temperature calcination formulation, the catalyst is obtained by calcining the complexed solution at 450-700℃ for 0.5-1h; Throughout the preparation process, a clean and dry operating environment must be maintained to prevent dust, oil, and other impurities from contaminating the metal salt solution. This is to prevent impurities from interfering with the complexation reaction and reducing catalyst purity. When adding S1, it is recommended to slowly add various solid metal salts to deionized water in batches while stirring at a low speed. This avoids excessively high local concentrations and salt agglomeration that are difficult to dissolve due to large-scale addition at once. The stirring rate must be controlled within a reasonable range to ensure dissolution efficiency while preventing excessive air bubbles introduced by high-speed stirring, which could affect the uniformity of subsequent complexation. When adding the complexing agent in S2, it should be added slowly only after the metal salt solution has been initially homogenized to avoid a sudden increase in local concentration of the complexing agent, which could lead to excessively rapid local complexation and precipitation. After adding the complexing agent, extend the stirring time appropriately to ensure complete dispersion and dissolution. During the S3 constant temperature complexing stage, ensure that the ambient temperature is stable without significant fluctuations and maintain a uniform stirring speed to prevent local overheating or stratification of the solution. This will promote the full chelation of metal ions and the complexing agent to form a stable and uniform complexing system, avoiding the aggregation of active components during subsequent calcination. Before S4 calcination, ensure that the complexing solution has no obvious precipitation or impurities. During calcination, control the heating rate to be gradual to avoid rapid heating that could cause the solution to boil over or splash. Maintain a stable atmosphere during the calcination process to prevent abnormal oxidation environment from affecting the crystal structure of the catalyst. After calcination, allow the solution to cool naturally to avoid sudden cooling that could cause the catalyst structure to crack and its performance to decline. The catalyst obtained in the above steps was activated by reducing it at 700°C under a reducing atmosphere for a period of time. Then, ethylene was introduced, and chemical vapor deposition was carried out under the action of the catalyst to obtain multi-walled carbon nanotubes. Furthermore, the volume ratio of hydrogen to nitrogen in the reducing atmosphere is 1:1; Furthermore, the carbon source gas is one or more of methane, propylene, and ethylene, and the volume ratio of the introduced carbon source to nitrogen is 1:1.

[0008] Preferably, the active metal salt in S1 is a mixture of water-soluble iron and cobalt salts, the carrier metal salt in S1 is a mixture of water-soluble aluminum and magnesium salts, the auxiliary metal salt in S1 is a soluble molybdate, and the complexing agent in S2 is ethylenediaminetetraacetic acid. The complexing agent can also be citric acid. The selected metal salts all have good water solubility and can quickly dissociate into ions in water, which is conducive to subsequent uniform mixing and complexation reaction. The complexing agent can be selected as needed. Both can form stable chelates with metal ions, effectively inhibit ion aggregation, ensure uniform dispersion of active components, and improve the stability of catalyst performance.

[0009] Preferably, the iron salt, cobalt salt, aluminum salt, magnesium salt and molybdate in S1 are respectively selected as ferric nitrate nonahydrate, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, magnesium nitrate hexahydrate and ammonium molybdate tetrahydrate; The salts are all high-purity water-soluble nitrates and molybdates with low impurity content and good solubility. They can quickly dissociate into metal ions in deionized water, avoiding the residue of insoluble impurities. At the same time, the thermal decomposition temperature is moderate, and they can be completely decomposed into the corresponding metal oxides during calcination without harmful residues, ensuring the activity and purity of the catalyst.

[0010] Preferably, in S1, the molar ratio of metal elements in the active metal salt to the carrier metal salt is 1:0.6-2.5; the molar ratio of iron to cobalt in the active metal salt is 1.6-6.25:1; the molar ratio of aluminum to magnesium in the carrier metal salt is 650:1; and the molar ratio of auxiliary metal elements to total metal elements is 26:100. The above formulation aims to balance catalytic activity, structural stability, and dispersion. The proportion of active components ensures catalytic efficiency, while the support ratio balances dispersion and thermal stability. Trace additives regulate the electronic structure, optimize the synergistic effect between components, avoid agglomeration, and improve the overall performance of the catalyst.

[0011] Preferably, the complexing agent in S2 is citric acid, and the mass of the complexing agent is 10-25% of the total mass of the active metal salt, the carrier metal salt, and the auxiliary metal salt. The complexing temperature in S3 is 70°C, and the stirring time is 2 hours. The calcination temperature in S4 is 500°C, and the calcination time is 0.5 hours. This amount of citric acid can fully chelate various metal ions. A constant temperature of 70°C combined with two hours of stirring ensures a thorough and balanced complexation reaction. Short-time calcination at 500°C can steadily complete the decomposition and shaping of the precursor, avoiding the problem of component sintering and agglomeration while preserving the ideal pore structure of the catalyst and ensuring subsequent catalytic effects.

[0012] Preferably, the reaction vessel used in S1-S4 further includes: a mounting base; The housing is mounted on top of the mounting base via a bracket. Multiple zone temperature control devices are mounted on the inner surface of the housing, and reaction structures are mounted on the inner surfaces of the multiple zone temperature control devices. A discharge assembly is installed at the outlet of the reaction structure, and a feed pipe is installed at the top of the reaction structure; A temperature control device, wherein the temperature control device is installed on the top of the mounting base; Valves are installed on the feed pipes, and the temperature control equipment can perform the required temperature control on multiple zone temperature control devices. During equipment assembly, it is necessary to ensure that the mounting base is placed horizontally and stably, and that the outer shell is reliably fixed to the base with the support. The zoned temperature control equipment should fit closely to the inner wall of the outer shell and be tightly assembled with the reaction structure. The valves at the feed pipe and discharge components should be flexible in opening and closing and tightly sealed. The wiring and pipeline connections of the temperature control equipment should be standardized, and the installation and alignment of each component should be accurate. After the overall assembly is completed, the sealing of the interfaces and the tightness of the components should be checked one by one.

[0013] Preferably, the mounting base includes a base plate, a mounting structure, and an adjustment structure. The mounting structure is used to mount the adjustment structure on the bottom of the base plate, and a control box with a door is mounted on the top of the mounting base. The mounting and adjustment structures are threadedly connected, allowing for adjustment of the base plate's stability as needed. The control box contains power switches and controllers for auxiliary equipment operation.

[0014] Preferably, the reaction structure includes a reaction vessel and a top cover, the top cover being mounted on top of the reaction vessel.

[0015] Preferably, a drive structure is installed on the top of the reaction structure, and a dual-shaft stirring assembly is installed at the output end of the drive structure. The dual-shaft stirring assembly includes a rotating shaft and stirring blades. The stirring blades are installed on the outer surface of the rotating shaft. The discharge assembly includes a discharge valve and a discharge pipe. The discharge valve is used to install the discharge pipe at the outlet of the reaction structure. The drive structure includes a housing, motor, gears, and chain, which can drive two rotating shafts to rotate synchronously.

[0016] Preferably, the reaction structure is internally equipped with a filter assembly, which includes a conical interceptor, a discharge pipe, and a drain valve. The discharge pipe is used to install the drain valve at the outlet of the conical interceptor.

[0017] Compared with related technologies, the preparation method of the catalyst for synthesizing carbon nanotubes provided by the present invention has the following beneficial effects: This invention provides a method for preparing a catalyst for synthesizing carbon nanotubes. This method involves only four steps: dissolution, complexation, stirring, and calcination. It is simple to operate, requires no complex specialized equipment, and features mild and controllable process conditions. The complexation temperature is 60-90℃, the calcination temperature is 450-700℃, and the calcination time is only 0.5-1 hour, significantly shortening the preparation cycle and greatly reducing energy consumption and production costs. It effectively overcomes the drawbacks of traditional processes, such as cumbersome steps, harsh conditions, and high costs. Furthermore, by employing standardized raw material ratios, complexation parameters, and calcination conditions, the preparation process is highly controllable, with batch-to-batch consistency. With good repeatability, this catalyst avoids performance fluctuations caused by operational differences, meeting the actual needs of large-scale continuous industrial production. It can achieve uniform dispersion of active components, enhance the synergistic effect between the support and active components, and the multi-walled carbon nanotubes synthesized by the catalyst have complete structures, high purity, excellent electrochemical performance, low resistivity of 63 mΩ・cm, outstanding conductivity, and excellent thermal stability. The fastest weight loss rate temperature can reach 705℃, which solves the problem of balancing the electrochemical performance and thermal stability of carbon nanotubes. It is suitable for high-end application scenarios such as conductive materials, energy storage devices, and high-performance composite materials. Attached Figure Description

[0018] Figure 1 A flowchart illustrating the preparation method of the catalyst for synthesizing carbon nanotubes provided by this invention; Figure 2 A proportioning diagram of each raw material is provided for this invention; Figure 3 This is a schematic diagram of the reaction vessel in the preparation method of the catalyst for synthesizing carbon nanotubes provided by the present invention; Figure 4 A schematic diagram of the temperature control device is provided for this invention; Figure 5 Provided for the present invention Figure 4 An enlarged view of point A shown; Figure 6 Provided for the present invention Figure 4 An enlarged view of point B shown; Figure 7 Provided for the present invention Figure 4 A magnified view of point C shown.

[0019] The diagram is labeled as follows: 1. Mounting base frame, 101. Base plate, 102. Mounting structure, 103. Adjustment structure, 2. Control box, 3. Discharge assembly, 301. Discharge valve, 302. Discharge pipe, 4. Box door, 5. Temperature control equipment, 6. Bracket, 7. Outer shell, 8. Reaction structure, 801. Reactor, 802. Top cover, 9. Feed pipe, 10. Drive structure, 11. Dual-shaft stirring assembly, 111. Rotating shaft, 112. Stirring blade, 12. Filter assembly, 121. Conical interception component, 122. Drain pipe, 123. Drain valve, 13. Zoned temperature control equipment. 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 , Figure 2 ,in, Figure 1 A flowchart illustrating the preparation method of the catalyst for synthesizing carbon nanotubes provided by this invention; Figure 2 A proportioning diagram of each raw material is provided for this invention. The preparation method of the catalyst for synthesizing carbon nanotubes includes the following steps: mixing 10.9g of ferric nitrate nonahydrate, 3.5g of cobalt nitrate hexahydrate, 28.6g of aluminum nitrate nonahydrate, 0.5g of magnesium nitrate hexahydrate, 0.6g of ammonium molybdate tetrahydrate, and 8.9g of citric acid together, and mixing with deionized water, stirring until initially dissolved to obtain a metal salt solution;

[0022] Add citric acid to the metal salt solution and continue stirring until completely dissolved to obtain a mixed solution; The mixed solution was placed at 70°C and stirred continuously for 2 hours to ensure that all raw materials were fully complexed and homogeneous. The catalyst is obtained by calcining the complexed solution at 500°C for 0.5 h.

[0023] Compared with related technologies, the preparation method of the catalyst for synthesizing carbon nanotubes provided by the present invention has the following beneficial effects: This method uses the highest amount of aluminum nitrate and the lowest amount of magnesium nitrate. The high proportion of aluminum salt in the carrier component provides sufficient high specific surface area carrier sites, effectively anchoring the iron and cobalt active components and inhibiting the agglomeration of active particles. The amount of citric acid is 8.9g, which accounts for a relatively high proportion of the total mass of metal salts, resulting in sufficient complexation and uniform dispersion of metal ions. The resistivity of the multi-walled carbon nanotubes synthesized by the catalyst is 66mΩ·cm, and the fastest weight loss rate temperature reaches 709℃. Compared with the comparative example, its conductivity is significantly improved and its thermal stability is significantly enhanced. The high aluminum and low magnesium ratio ensures the dispersibility of active components, and the sufficient amount of complexing agent avoids agglomeration, achieving a balance between the structural integrity and thermal stability of carbon nanotubes. This method is suitable for energy storage materials with high requirements for thermal stability.

[0024] Second Embodiment Please refer to the following: Figure 1 , Figure 2 ,in, Figure 1 A flowchart illustrating the preparation method of the catalyst for synthesizing carbon nanotubes provided by this invention; Figure 2 A proportioning diagram of each raw material is provided for this invention. The preparation method of the catalyst for synthesizing carbon nanotubes includes the following steps: mixing 10.9g of ferric nitrate nonahydrate, 3.5g of cobalt nitrate hexahydrate, 9.1g of aluminum nitrate nonahydrate, 0.8g of magnesium nitrate hexahydrate, 0.6g of ammonium molybdate tetrahydrate, and 4.9g of citric acid together, and mixing with deionized water, stirring until initially dissolved to obtain a metal salt solution;

[0025] Add citric acid to the metal salt solution and continue stirring until completely dissolved to obtain a mixed solution; The mixed solution was placed at 70°C and stirred continuously for 2 hours to ensure that all raw materials were fully complexed and homogeneous. The catalyst is obtained by calcining the complexed solution at 500°C for 0.5 h.

[0026] Compared with related technologies, the preparation method of the catalyst for synthesizing carbon nanotubes provided by the present invention has the following beneficial effects: In this preparation method, the amounts of iron salt, cobalt salt, and molybdate are the same as in the first embodiment. The amount of aluminum nitrate is reduced to 9.1g, magnesium nitrate is increased to 0.8g, and citric acid is reduced to 4.9g. The metal salt ratio is more balanced, with a reduction in aluminum salt and a slight increase in magnesium salt. The specific surface area of ​​the support is appropriately reduced, and the thermal stability of the support is enhanced to avoid excessive support affecting the catalytic efficiency of the active components. The amount of citric acid is matched with the total amount of metal salts, ensuring sufficient complexation while avoiding excessive complexing agent residue affecting catalyst activity. The resistivity of the multi-walled carbon nanotubes synthesized by the catalyst is as low as 63mΩ·cm, the lowest among the three groups, and the fastest weight loss rate temperature reaches 704℃. This ratio achieves the optimal balance between the catalytic activity of the active components, the stability of the support, and the complexation effect. The carbon nanotubes have the best conductivity and maintain a high level of thermal stability, making them suitable for conductive composite materials, electrode materials, and other scenarios with high conductivity requirements, resulting in the best overall performance.

[0027] Third Embodiment Please refer to the following: Figures 3-4 - Figures 5-6 - Figure 7 , Figure 3 This is a schematic diagram of the reaction vessel in the preparation method of the catalyst for synthesizing carbon nanotubes provided by the present invention; Figure 4 A schematic diagram of the temperature control device is provided for this invention; Figure 5 Provided for the present invention Figure 4 An enlarged view of point A shown; Figure 6 Provided for the present invention Figure 4 An enlarged view of point B shown; Figure 7 Provided for the present invention Figure 4 The enlarged view at point C shows a method for preparing a catalyst for synthesizing carbon nanotubes based on the first embodiment of this application. The second embodiment of this application proposes another method for preparing a catalyst for synthesizing carbon nanotubes. The second embodiment is merely a preferred embodiment of the first embodiment, and its implementation will not affect the independent implementation of the first embodiment.

[0028] Specifically, the difference in the preparation method of the catalyst for synthesizing carbon nanotubes provided in the second embodiment of this application is that the reaction vessel used in S1-S4 further includes: a mounting base 1; The outer casing 7 is mounted on the top of the mounting base 1 via a bracket 6. Multiple zone temperature control devices 13 are mounted on the inner surface of the outer casing 7, and a reaction structure 8 is mounted on the inner surface of the multiple zone temperature control devices 13. Discharge assembly 3 is installed at the outlet of reaction structure 8, and feed pipe 9 is installed on the top of reaction structure 8; Temperature control device 5, which is installed on the top of the mounting base 1; Valves are installed on the feed pipe 9, and the temperature control device 5 can perform the required temperature control on multiple zone temperature control devices 13; During equipment assembly, it is necessary to ensure that the mounting base 1 is placed horizontally and stably, the outer shell 7 is reliably fixed to the base with the support 6, the zone temperature control device 13 is closely fitted to the inner wall of the outer shell 7 and tightly assembled with the reaction structure 8, the valves of the feed pipe 9 and discharge component 3 are flexible to open and close and tightly sealed, the wiring and pipeline connection of the temperature control device 5 are standardized, the installation and alignment of each component are accurate, and after the overall assembly is completed, the interface sealing and component fastening status are checked one by one. The zoned temperature control device 13 consists of an independent heating unit, a temperature sensor, and connecting lines. It is installed in sections attached to the outer wall of the reaction structure. It receives the control signals from the temperature control device 5, and each zone independently collects temperature and adjusts the heating power. Heat is transferred through contact heat conduction, so as to realize the separate control of the temperature of different sections of the reaction structure and ensure the overall temperature distribution is balanced.

[0029] Please refer to Figure 3 and Figure 4 The mounting base 1 includes a base plate 101, a mounting structure 102 and an adjustment structure 103. The mounting structure 102 is used to install the adjustment structure 103 at the bottom of the base plate 101. A control box 2 with a door 4 is installed on the top of the mounting base 1. The threaded connection between the mounting structure 102 and the adjustment structure 103 allows for adjustment of the stability of the base plate 101 as needed. The control box 2 contains a power switch and a controller for the operation of auxiliary equipment.

[0030] Please refer to Figure 3 and Figure 4 The reaction structure 8 includes a reaction vessel 801 and a top cover 802, the top cover 802 being installed on top of the reaction vessel 801; The top cover 802 and the reactor 801 are secured together by snap fasteners to ensure a tight seal. The reactor 801 is made of a material with high thermal conductivity.

[0031] Please refer to Figure 4 , Figure 6 and Figure 7 The top of the reaction structure 8 is equipped with a drive structure 10, and the output end of the drive structure 10 is equipped with a dual-shaft stirring assembly 11. The dual-shaft stirring assembly 11 includes a rotating shaft 111 and stirring blades 112. The stirring blades 112 are installed on the outer surface of the rotating shaft 111. The discharge assembly 3 includes a discharge valve 301 and a discharge pipe 302. The discharge valve 301 is used to install the discharge pipe 302 at the outlet of the reaction structure 8. The drive structure 10 includes a housing, a motor, gears, and a chain, which can drive two rotating shafts 111 to rotate synchronously.

[0032] Please refer to Figure 4 and Figure 5 The reaction structure 8 is equipped with a filter assembly 12, which includes a conical interceptor 121, a discharge pipe 122 and a drain valve 123. The discharge pipe 122 is used to install the drain valve 123 at the outlet of the conical interceptor 121. The discharge pipe 122 passes through the reaction structure 8, the zoned temperature control device 13, and the outer shell 7, and the connection needs to be sealed.

[0033] Compared with related technologies, the preparation method of the catalyst for synthesizing carbon nanotubes provided by the present invention has the following beneficial effects: To improve the uniformity of stirring and the preparation effect during catalyst preparation, this device installs a zoned temperature control device 13 on the outer surface of the reaction structure 8. This device works in conjunction with the temperature control device 5 to heat the top, middle, and bottom of the reaction structure 8 in separate zones. The zoned temperature control device 13 and the temperature control device 5 are interconnected, allowing for precise temperature control of different areas of the reaction structure 8. This effectively solves the problems of uneven temperature distribution, local overheating, or insufficient temperature that exist in traditional single-stage heating methods. This ensures a uniform and stable temperature field inside the reaction structure 8, precisely matching the temperature conditions required for each stage of catalyst preparation—dissolution, complexation, and isothermal ripening—ensuring that each reaction step proceeds fully at the appropriate temperature, significantly improving the overall catalyst preparation effect. Simultaneously, the device drives the biaxial stirring assembly 11 via the drive structure 10. The biaxial stirring assembly 11 operates within the reaction structure... The internal structure 8 generates a high-intensity, all-around stirring action, which allows various raw materials to be rapidly dispersed and fully mixed within the reaction structure 8. This avoids localized excessive material concentrations or uneven mixing, ensuring that the active metal salt, carrier metal salt, auxiliary metal salt, and complexing agent achieve full contact and uniform complexation at the corresponding temperature environment. This significantly improves the mixing efficiency and uniformity of the raw materials, laying the foundation for the uniform dispersion of the catalyst's active components. In addition, the reaction structure 8 is equipped with a filter component 12, which can promptly intercept particulate impurities, incompletely dissolved agglomerates, and other unqualified raw materials during the mixing and reaction process. This prevents impurities from being mixed into the subsequent calcination process, affecting the purity and performance of the catalyst. This ensures the purity of the raw material system from the source, further optimizes the quality of catalyst preparation, and effectively improves the performance stability and batch consistency of the final catalyst.

[0034] 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's 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 a catalyst for synthesizing carbon nanotubes, characterized in that, Includes the following steps: S1: Metal salt dissolution: According to the preset ratio, the active metal salt, carrier metal salt, auxiliary metal salt and deionized water are mixed in the reaction vessel and stirred until initially dissolved to obtain a metal salt solution; S2: Complexing agent mixing: Add complexing agent to metal salt solution and continue stirring until completely dissolved to obtain mixed solution; S3: Constant temperature complexation and maturation. Place the mixed solution in an environment of 60-90℃ and stir continuously for 1-3 hours to ensure that the raw materials are fully complexed and uniform. S4: High-temperature calcination preparation, the catalyst is obtained by calcining the complexed solution at 450-700℃ for 0.5-1h.

2. The method for preparing the catalyst for synthesizing carbon nanotubes according to claim 1, characterized in that, The active metal salt in S1 is a mixture of water-soluble iron and cobalt salts; the carrier metal salt in S1 is a mixture of water-soluble aluminum and magnesium salts; the auxiliary metal salt in S1 is a soluble molybdate; and the complexing agent in S2 is ethylenediaminetetraacetic acid.

3. The method for preparing the catalyst for synthesizing carbon nanotubes according to claim 1, characterized in that, The iron salt, cobalt salt, aluminum salt, magnesium salt, and molybdate in S1 are selected from iron nitrate nonahydrate, cobalt nitrate hexahydrate, aluminum nitrate nonahydrate, magnesium nitrate hexahydrate, and ammonium molybdate tetrahydrate, respectively.

4. The method for preparing the catalyst for synthesizing carbon nanotubes according to claim 3, characterized in that, In S1, the molar ratio of metal elements in the active metal salt to the carrier metal salt is 1:0.6-2.5; the molar ratio of iron to cobalt in the active metal salt is 1.6-6.25:1; the molar ratio of aluminum to magnesium in the carrier metal salt is 650:1; and the molar ratio of auxiliary metal elements to total metal elements is 26:

100.

5. The method for preparing the catalyst for synthesizing carbon nanotubes according to claim 1, characterized in that, Citric acid is selected as the complexing agent in S2, and the mass of the complexing agent is 10-25% of the total mass of the active metal salt, carrier metal salt, and auxiliary metal salt. The complexing temperature in S3 is 70°C and the stirring time is 2 hours. The calcination temperature in S4 is 500°C and the calcination time is 0.5 hours.

6. The method for preparing a catalyst for synthesizing carbon nanotubes according to claim 1, wherein the reaction vessel used in steps S1-S4 is characterized in that, Also includes: Install the base frame; The housing is mounted on top of the mounting base via a bracket. Multiple zone temperature control devices are mounted on the inner surface of the housing, and reaction structures are mounted on the inner surfaces of the multiple zone temperature control devices. A discharge assembly is installed at the outlet of the reaction structure, and a feed pipe is installed at the top of the reaction structure; Temperature control device, which is installed on the top of the mounting base.

7. The method for preparing the catalyst for synthesizing carbon nanotubes according to claim 6, characterized in that, The mounting base includes a base plate, a mounting structure, and an adjustment structure. The mounting structure is used to install the adjustment structure at the bottom of the base plate, and a control box with a door is installed at the top of the mounting base.

8. The method for preparing the catalyst for synthesizing carbon nanotubes according to claim 6, characterized in that, The reaction structure includes a reaction vessel and a top cover, the top cover being installed on top of the reaction vessel.

9. The method for preparing the catalyst for synthesizing carbon nanotubes according to claim 6, characterized in that, A drive structure is installed on the top of the reaction structure, and a dual-shaft stirring assembly is installed at the output end of the drive structure. The dual-shaft stirring assembly includes a rotating shaft and stirring blades. The stirring blades are installed on the outer surface of the rotating shaft. The discharge assembly includes a discharge valve and a discharge pipe. The discharge valve is used to install the discharge pipe at the outlet of the reaction structure.

10. The method for preparing the catalyst for synthesizing carbon nanotubes according to claim 6, characterized in that, The reaction structure is internally equipped with a filter assembly, which includes a conical interceptor, a discharge pipe, and a drain valve. The discharge pipe is used to install the drain valve at the outlet of the conical interceptor.

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