Arrayed carbon nanotubes and methods of making the same

Abstract

The application relates to the technical field of material synthesis, and provides an array carbon tube and a preparation method thereof. The preparation method of the array carbon tube comprises the following steps: providing a nickel-based catalyst with a particle size in a preset range and a specific surface area in a preset specific surface area range; introducing the nickel-based catalyst and a first carbon source atmosphere into an array carbon tube growth device, reacting at a first reaction temperature for a first reaction time, and obtaining a first reaction product; introducing the first reaction product and a second carbon source atmosphere into the array carbon tube growth device, reacting at a second reaction temperature for a second reaction time, and obtaining the array carbon tube. Through the above scheme, the problem of the electrical conductivity of the coarse-pipe-diameter carbon nanotube is solved, and a new means for adjusting the array carbon tube is provided.

Description

Technical Field

[0001] This application belongs to the field of materials synthesis technology, and in particular relates to an array of carbon nanotubes and its preparation method. Background Technology

[0002] Carbon nanotubes are one-dimensional quantum materials with a unique structure. Their structure primarily consists of several to dozens of layers of coaxial cylindrical tubes arranged in a hexagonal pattern, exhibiting excellent electrical and thermal conductivity. In the field of conductive agents, larger-diameter carbon nanotubes are easier to disperse than smaller-diameter ones, and their larger inner diameter allows for easier loading of active components, thus resulting in superior performance. However, in current technologies, larger-diameter carbon nanotubes still suffer from poor electrical conductivity, a problem that urgently needs to be addressed. Summary of the Invention

[0003] The purpose of this application is to provide an array of carbon nanotubes and a method for preparing the same, which can improve the electrical conductivity of large-diameter carbon nanotubes.

[0004] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0005] In a first aspect, this application provides a method for preparing arrayed carbon nanotubes, the method comprising:

[0006] Provide a nickel-based catalyst with a particle size within a preset range and a specific surface area within a preset specific surface area range;

[0007] The nickel-based catalyst and the first carbon source atmosphere are introduced into the array carbon nanotube growth device and reacted at the first reaction temperature for the first reaction time to obtain the first reactant.

[0008] The first reactant and the second carbon source atmosphere are introduced into the array carbon nanotube growth device, and the reaction is carried out at the second reaction temperature for the second reaction time to obtain the array carbon nanotubes.

[0009] Preferably, the provision of a nickel-based catalyst comprises:

[0010] Metal salts and foaming agents are mixed and dissolved according to a preset ratio, and the pH is adjusted to a preset value to obtain a mixed solution;

[0011] The mixture is placed at a first preset temperature to react, yielding reactants;

[0012] The reactants are calcined at a second preset temperature for a preset time to obtain a catalyst support; the catalyst support has a specific surface area of ​​50–230 m². 3 / g;

[0013] The nickel-containing reagent and the catalyst support were placed under a first preset condition to react and obtain a preproduct.

[0014] The preproduct was subjected to a reduction reaction under preset reduction conditions to obtain a nickel-based catalyst.

[0015] Preferably, the metal salt includes magnesium salt and / or aluminum salt, and the foaming agent includes citric acid. Correspondingly, the step of mixing and dissolving the metal salt and foaming agent according to a preset ratio, adjusting the pH to a preset value, and obtaining a mixed solution includes:

[0016] Magnesium salts and / or aluminum salts are mixed and dissolved with citric acid in a preset ratio, and the pH is adjusted to the preset value to obtain a mixed solution.

[0017] Preferably, the step of placing the nickel-containing reagent and the catalyst support under a first preset condition to react and obtain the preproduct includes:

[0018] The nickel-containing reagent and reaction aid are mixed and dissolved according to a preset molar ratio, and a dispersant is added to obtain a mixture;

[0019] The catalyst support is added to the mixture, and an impregnation operation is performed under a second preset condition.

[0020] The impregnated catalyst support is removed and subjected to solid-liquid separation to obtain primary impregnated powder.

[0021] The above impregnation operation is repeated on the once-impregnated powder to obtain a pre-product.

[0022] Preferably, the nickel-containing reagent includes a nickel salt, the reaction aid includes a calcium salt, and the dispersant includes polyvinyl alcohol. Correspondingly, the step of mixing and dissolving the nickel-containing reagent and the reaction aid at a preset molar ratio, adding the dispersant, and obtaining a mixture includes:

[0023] Nickel salt and calcium salt are mixed and dissolved according to a preset molar ratio, and polyvinyl alcohol is added to obtain a mixture.

[0024] Preferably, the step of adding the catalyst support to the mixture and performing an impregnation operation under a second preset condition includes:

[0025] The catalyst support is added to the mixture, and an impregnation operation is performed under ultrasonic conditions.

[0026] The process of removing the impregnated catalyst support and performing solid-liquid separation to obtain primary impregnated powder includes:

[0027] The impregnated catalyst support is removed and dried at a third preset temperature to obtain a first-impregnated powder.

[0028] Preferably, the step of repeatedly performing the above impregnation operation on the once-impregnated powder to obtain a pre-product includes:

[0029] The primary impregnated powder is mixed with the remaining liquid in the mixture and placed in an ultrasonic environment for a preset time. The impregnated powder is then removed and dried to obtain the secondary impregnated powder.

[0030] Repeat the above impregnation operation until the mixture is completely impregnated to obtain the pre-product.

[0031] Preferably, the first carbon source atmosphere is an alkyne, more preferably acetylene; the second carbon source atmosphere is an alkane, more preferably methane.

[0032] Preferably, the nickel-based catalyst has a pore size of 0.2–2 μm, a particle size of 2–50 μm, and a specific surface area of ​​30–150 m². 3 / g.

[0033] Secondly, this application provides an array carbon nanotube, which is prepared using the method described in the first aspect.

[0034] Beneficial effects of this application

[0035] This application provides a method for preparing carbon nanotube arrays. The method includes: providing a nickel-based catalyst with a particle size within a preset range and a specific surface area within a preset specific surface area range; introducing the nickel-based catalyst and different carbon sources into a carbon nanotube array growth device to obtain carbon nanotube arrays.

[0036] This application focuses on solving the problem of poor conductivity from two aspects:

[0037] First, reduce the entanglement of carbon nanotubes and improve their original dispersion properties.

[0038] Second, reducing defects in carbon nanotubes and increasing their graphitization level can improve their metallic conductivity. Specifically, this is achieved by adjusting the particle size and specific surface area of ​​the nickel-based catalyst and by using different carbon source reactions in stages during the preparation process to obtain arrayed carbon nanotubes with less entanglement and fewer defects. This approach can solve the conductivity problem of large-diameter carbon nanotubes and provides a new means of regulating arrayed carbon nanotubes. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is one of the flowcharts of a method for preparing an array of carbon nanotubes provided in the embodiments of this application;

[0041] Figure 2 This is the second flowchart of a method for preparing an array of carbon nanotubes provided in the embodiments of this application;

[0042] Figure 3 This is the third flowchart of a method for preparing an array of carbon nanotubes provided in the embodiments of this application;

[0043] Figure 4 This is one of the electron microscope images of the arrayed carbon nanotubes provided in the embodiments of this application;

[0044] Figure 5 This is the second electron microscope image of the arrayed carbon nanotubes provided in the embodiments of this application;

[0045] Figure 6 This is the third electron microscope image of the arrayed carbon nanotubes provided in the embodiments of this application. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] For ease of description, the terms "first," "second," etc., used in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of a person skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination should be considered non-existent and not within the scope of protection claimed by this invention.

[0048] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0049] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0050] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0051] Carbon nanotubes are one-dimensional quantum materials with a unique structure and excellent electrical and thermal conductivity. In existing technologies, large-diameter carbon nanotubes are easier to disperse than small-diameter ones, and their larger inner diameter makes it easier to load active components, thus resulting in superior performance. However, the electrical conductivity of large-diameter carbon nanotubes is currently weak, and existing technologies do not know how to improve this conductivity. Therefore, this application proposes a method for preparing arrayed carbon nanotubes.

[0052] Figure 1 This document shows one of the flowcharts illustrating a method for preparing an array of carbon nanotubes according to an embodiment of this application.

[0053] Reference Figure 1 The method for preparing an array of carbon nanotubes provided in this application includes the following steps:

[0054] Step S100: Provide a nickel-based catalyst with a particle size within a preset range and a specific surface area within a preset specific surface area range;

[0055] Step S101: Introduce the nickel-based catalyst and the first carbon source atmosphere into the array carbon nanotube growth device, react at the first reaction temperature for the first reaction time, and obtain the first reactant;

[0056] Step S102: The first reactant and the second carbon source atmosphere are introduced into the carbon nanotube array growth apparatus, and the reaction is carried out at the second reaction temperature for the second reaction time to obtain the carbon nanotube array.

[0057] The inventors of this application, through inventive research, discovered a certain correlation between the particle size and specific surface area of ​​nickel-based catalysts and the conductivity of arrayed carbon nanotubes. Therefore, by adjusting the particle size and specific surface area of ​​the nickel-based catalyst and by using different carbon source reactions in stages during the preparation process, arrayed carbon nanotubes with less entanglement and fewer defects can be obtained. The nickel-based catalyst has a pore size of 0.2–2 μm, a particle size of 2–50 μm, and a specific surface area of ​​30–150 m². 3 / g. The specific surface area of ​​the catalyst support used for supporting nickel metal is 50–230 m². 3 / g.

[0058] It can be seen that, through Figure 1The illustrated embodiment can solve the conductivity problem of large-diameter carbon nanotubes, and at the same time provides a new means of regulating arrayed carbon nanotubes.

[0059] The following is about Figure 1 Step S100 will be described in detail, such as Figure 2 As shown, Figure 2 This illustrates a second flowchart of a method for preparing an array of carbon nanotubes according to an embodiment of this application. Figure 1 The specific steps of step S100 are detailed below. Refer to... Figure 2 Step S100 specifically includes the following steps:

[0060] Step S200: Mix and dissolve the metal salt and foaming agent according to a preset ratio, adjust the pH to a preset value, and obtain a mixed solution;

[0061] Step S201: The above mixture is placed at a first preset temperature to react and obtain reactants;

[0062] Step S202: The above reactants are calcined at a second preset temperature for a preset time to obtain a catalyst support; the catalyst support has a specific surface area of ​​50-230 m². 3 / g;

[0063] Step S203: The nickel-containing reagent and the above-mentioned catalyst support are placed under the first preset conditions to react and obtain the preproduct;

[0064] Step S204: The preproduct is placed under preset reduction conditions to undergo a reduction reaction to obtain a nickel-based catalyst.

[0065] Among them, foaming agent refers to any surfactant or surface-active substance whose aqueous solution can generate a large amount of foam when air is introduced, such as citric acid or citrate.

[0066] Among them, nickel-containing reagents can be metallic nickel or salts containing nickel ions, including nickel chloride, nickel nitrate, nickel sulfate, etc.

[0067] The acidity or alkalinity refers to the pH value of the solution. The preset value can be 6 to 8, and the specific value can be 6, 6.5, 7, 7.5 or 8. The acidity or alkalinity can be adjusted by using alkaline precipitants, such as ammonia or ammonium bicarbonate.

[0068] The preset ratio of metal salt, citric acid and alkaline precipitant, i.e., molar ratio, is 1:(1.05~1.2):(1.05~1.2).

[0069] The first preset temperature can be in the range of 190 to 290℃, and the specific values ​​can include: 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃ or 290℃. Correspondingly, the reaction time of the mixture containing the foaming agent at the first preset temperature is 2 to 4 hours, and the specific values ​​can include: 2 hours, 2.5 hours, 3 hours, 3.5 hours or 4 hours.

[0070] The second preset temperature can be in the range of 400 to 600℃, and specific values ​​can include: 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, 560℃, 580℃ or 600℃.

[0071] The preset duration of the calcination process is 1 to 4 hours, and the specific values ​​can include 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours or 4 hours.

[0072] It should be noted that the specific values ​​mentioned above are examples, and other values ​​within the corresponding ranges are also included, which will not be elaborated upon in this application.

[0073] Metal salts are salts containing metal ions, and can be magnesium salts, aluminum salts, or a mixture of magnesium and aluminum salts. Magnesium salts can include magnesium nitrate, magnesium chloride, and magnesium sulfate, while aluminum salts can include aluminum nitrate, aluminum chloride, and aluminum sulfate.

[0074] When magnesium salt is used as the metal salt, for example, magnesium salt is mixed and dissolved with citric acid monohydrate according to a preset ratio, and the pH is adjusted to 7 to obtain a mixed solution. The mixed solution is then reacted at 200°C for 4 hours to obtain a reactant. The reactant is then calcined at 500°C for 2 hours to obtain a catalyst support. Nickel nitrate and the catalyst support are then placed under a first preset condition to react and obtain a nickel-based catalyst. It should be noted that when magnesium salt is used as the metal salt, the catalyst support obtained is MgO powder, which is pale yellow and loose.

[0075] When aluminum salt is used as the metal salt, for example, aluminum salt and citric acid monohydrate are mixed and dissolved according to a preset ratio, and the pH is adjusted to 8 to obtain a mixed solution. The mixed solution is then reacted at 240°C for 3 hours to obtain a reactant. The reactant is then calcined at 550°C for 2 hours to obtain a catalyst support. Nickel nitrate and the catalyst support are then placed under a first preset condition to react and obtain a nickel-based catalyst. It should be noted that when aluminum salt is used as the metal salt, the catalyst support obtained is Al2O3 powder, which is pale yellow and loose.

[0076] When the metal salt is a mixture of magnesium salt and aluminum salt, for example, magnesium salt, aluminum salt and citric acid monohydrate are mixed and dissolved in a preset ratio, the pH is adjusted to 8 to obtain a mixed solution, the mixed solution is placed at 240°C for 2.5 h to obtain a reactant, the reactant is placed at 550°C for 2 h to obtain a catalyst support, nickel nitrate and the catalyst support are placed under a first preset condition to react and obtain a nickel-based catalyst.

[0077] In the above embodiments of this application, a single-component support is preferred in the selection of the support composition. This reduces the probability that other impurity components will combine with the active metal to form other crystal structures, thereby reducing the generation of defects in the subsequent carbon nanotube growth process. Furthermore, this application employs an equal-volume impregnation method to impregnate the catalyst active components. By controlling the amount of foaming agent, the pore size of the catalyst support can be adjusted, thereby controlling the particle size of the catalyst support. Additionally, by controlling the first and second preset temperatures, the specific surface area of ​​the catalyst support can be adjusted, thereby controlling the catalyst loading and thus improving the catalyst conversion rate.

[0078] In an embodiment achievable in this application, step S204 may specifically involve adding the preproduct to a catalyst reduction and activation device, setting the reduction temperature to 350–420°C, the ratio of inert carrier gas to hydrogen in the reduction atmosphere to be (2–5:1), and the hydrogen flow rate to nickel-based catalyst mass ratio to be 0.1–0.5 L / min: 0.5–2 g. The reaction is carried out under the above conditions for 30–50 min to obtain the nickel-based catalyst.

[0079] It should be noted that the nickel-based catalyst prepared in the embodiments of this application has a pore size of 0.2–2 μm, a particle size of 2–50 μm, and a specific surface area of ​​30–150 m². 3 / g.

[0080] Through the above reduction reaction, the preproduct can be restored to its catalytic activity, so as to obtain a nickel-based catalyst with normal catalytic activity.

[0081] The following is about Figure 2 Step S203 will be explained in detail. Figure 3 This is a third flowchart illustrating a method for fabricating an array of carbon nanotubes according to an embodiment of this application. This flowchart details the steps of step S203. (Refer to...) Figure 3 Step S203: The nickel-containing reagent and the above-mentioned catalyst support are placed under the first preset conditions to react and obtain the preproduct, specifically including the following steps:

[0082] Step S300: Mix and dissolve the nickel-containing reagent and reaction aid according to a preset molar ratio, add a dispersant, and obtain a mixture;

[0083] Step S301: Add the catalyst support to the mixture and perform an impregnation operation under the second preset conditions;

[0084] Step S302: Remove the impregnated catalyst support and perform solid-liquid separation to obtain primary impregnated powder;

[0085] Step S303: Repeat the above impregnation operation on the once impregnated powder to obtain the pre-product.

[0086] Among them, the nickel-containing reagent can be metallic nickel or salts containing nickel ions, including nickel chloride, nickel nitrate, nickel sulfate, etc., mainly used to provide a nickel source as an active component of the catalyst.

[0087] Among them, reaction promoters help improve reaction efficiency, mainly including calcium salts, manganese salts, lanthanum salts, and ammonium molybdate, etc. Manganese nitrate, lanthanum nitrate, and calcium nitrate can be selected as promoters, or ammonium molybdate, ammonium metavanadate, and calcium nitrate can be selected as promoters. Preferably, a higher proportion of calcium salts and a lower proportion of other components result in the best catalytic activity. More calcium can form a certain crystal structure, making it easier to peel off active nickel.

[0088] The dispersant can be an alcohol-based reagent, such as polyvinyl alcohol or polyethylene glycol.

[0089] For example, step S300 includes: mixing and dissolving nickel nitrate, manganese nitrate, lanthanum nitrate and calcium nitrate in pure water at a preset molar ratio of 1:(0.1-0.5):(0.2-0.4):(0.8-2), and adding 0.1-2% of the dispersant polyvinyl alcohol to obtain a mixture.

[0090] In another embodiment of this application, the second preset condition in step S301 can be an ultrasonic condition. Correspondingly, step S301 can be adding a catalyst carrier to the mixture and performing an impregnation operation under ultrasonic conditions.

[0091] Specifically, a certain amount of catalyst support is added to the mixture, and the container containing the catalyst support and the mixture is placed in an ultrasonic bath for impregnation for 48 hours.

[0092] Through the above operations, the mixture can be fully adhered to the inner and outer surfaces of the catalyst support, so as to complete the impregnation.

[0093] The solid-liquid separation operation in step S302 can be static drying, oven drying, vacuum drying, or freeze drying. When a vacuum operation is used, step S302 includes: taking out the catalyst support saturated with liquid, placing it in a vacuum drying oven, and drying it at 120–240°C for 8 hours to obtain a single-impregnated powder.

[0094] Correspondingly, step S303 includes further impregnating the first-impregnated powder in the remaining mixture and placing it in an ultrasonic tank, repeating the above impregnation operation until all the mixture is impregnated to obtain impregnated powder.

[0095] It should be noted that the number of impregnations should not exceed 5, and the concentration of the remaining liquid after each impregnation should not exceed the saturation concentration of any nitrate, in order to avoid the precipitation of nitrate crystals and interference with the finished product.

[0096] Through the operations described in steps S300 to S303, the nickel-containing reagent and reaction aids are fully loaded onto the catalyst support to generate a nickel-based catalyst, facilitating the subsequent preparation of carbon nanotube arrays. Furthermore, this embodiment employs an equal-volume impregnation method to impregnate the catalyst active components. Unlike conventional impregnation methods, this method allows for control of the catalyst support particle size by adjusting the amount of foaming agent used. Additionally, it allows for control of the specific surface area of ​​the catalyst support by controlling the first and second preset temperatures, thereby controlling the catalyst loading and ultimately improving the catalyst conversion rate.

[0097] The following is about Figure 1 Steps S101 and S102 are described in detail.

[0098] The first carbon source can be an alkyne, preferably acetylene, and the second carbon source can be an alkane, preferably methane.

[0099] Among them, arrayed carbon nanotubes are carbon nanotubes.

[0100] For example, a nickel-based catalyst is fed into a primary reactor, and acetylene is introduced to react at a temperature of 350–540°C for 5–30 min. The acetylene flow rate to catalyst mass ratio is 0.5–1 L / min: 0.5–2 g, and the reaction yields a first reactant. The first reactant is then fed into a secondary reactor, and methane is introduced to react at a temperature of 750–1050°C for 20–50 min. The methane flow rate to catalyst mass ratio is 1–3 L / min: 0.5–2 g, and the reaction yields an array of carbon nanotubes. Figures 4-6 An electron microscope image of an array of carbon nanotubes provided in an embodiment of this application is shown, with reference to... Figures 4-6 The arrayed carbon nanotubes have a diameter of 40–60 nm, a length of 1–3 μm, an aspect ratio of (25–100):1, and a specific surface area of ​​80–120 m². 2 / g, D / G = 1.1~1.3. Furthermore, tests showed that the resistivity of the arrayed carbon nanotubes prepared in this application is 50~80 mΩ*cm, indicating good electrical conductivity.

[0101] It should be noted that the reaction in step S101 is the catalyst induction stage, and the reaction in step S102 is the array carbon nanotube growth stage.

[0102] It should be noted that methane is used as the second carbon source because methane decomposition has a high hydrogen partial pressure, and coupled with its cracking at a high temperature, these two factors reduce the defects in the arrayed carbon nanotubes and improve their electrical conductivity.

[0103] In the above embodiments of this application, nickel-based carbon nanotubes are used as the active component of the catalyst, and the aspect ratio of the prepared array carbon nanotubes is (25-100):1, while the aspect ratio of traditional iron-cobalt-based carbon nanotubes is (1000-10000):1. Therefore, the average diameter of the nickel-based array carbon nanotubes is relatively large, the specific surface area is low, and it can be used in high solids content conductivity. In addition, it has the characteristics of being easily dispersed, with less entanglement, which is also beneficial for use as a catalyst support.

[0104] The following description is based on specific embodiments.

[0105] Example 1

[0106] A certain amount of aluminum nitrate was dissolved in water, and an appropriate amount of citric acid monohydrate was added. After the citric acid was completely dissolved, a certain amount of ammonium carbonate was added to adjust the pH to 6.5. The mixed liquid was then placed in a vacuum drying oven at 225°C for expansion. After expansion, it was calcined in a muffle furnace at 500°C for 2 hours to obtain a light yellow and loose Al2O3 powder.

[0107] Nickel nitrate, manganese nitrate, lanthanum nitrate, and calcium nitrate were mixed and dissolved in pure water at a molar ratio of 1:0.3:0.2:0.8. A certain amount of catalyst carrier was placed in the mixed solution, and 0.8% polyvinyl alcohol was added. The container containing the catalyst carrier and the mixed liquid was placed in an ultrasonic bath for the first soaking for 48 hours. The carrier, which was saturated with liquid, was then placed in a vacuum drying oven at 200°C for 8 hours to obtain the powder for the second soaking. The remaining mixed liquid from the above process was poured into the powder that had been soaked and dried in the first soaking. This process was repeated until the mixed liquid had completely impregnated the powder.

[0108] The catalyst was added to a catalyst reduction and activation device at a reduction temperature of 400℃ for 350 min. The ratio of inert carrier gas to hydrogen in the reducing atmosphere was 3:1, and the hydrogen flow rate to catalyst mass ratio was 0.25 L / min:0.5 g. The catalyst was then fed into a primary reactor, where acetylene was introduced. The reaction temperature was 450℃ for 25 min, and the carbon source flow rate to catalyst mass ratio was 0.6 L / min:0.9 g. The carbon nanotube intermediate was then fed into a secondary reactor, where methane was introduced. The reaction temperature was 750℃ for 30 min, and the carbon source flow rate to catalyst mass ratio was 2 L / min:1.5 g. The reaction yielded an array of coarse nanotubes.

[0109] The prepared carbon nanotube arrays had an aspect ratio of (25–50):1 and a specific surface area of ​​80–100 m². 2 / g, powder resistivity is 58mΩ*cm.

[0110] Example 2

[0111] A certain amount of magnesium nitrate was dissolved in water, and an appropriate amount of citric acid monohydrate was added. After the citric acid was completely dissolved, a certain amount of ammonia was added to adjust the pH to 8. The mixed liquid was then placed in a vacuum drying oven at 210°C for expansion. After expansion, it was calcined in a muffle furnace at 500°C for 2 hours to obtain a light yellow and loose MgO powder.

[0112] Nickel nitrate, manganese nitrate, lanthanum nitrate, and calcium nitrate were mixed and dissolved in pure water at a molar ratio of 1:0.4:0.3:0.9. A certain amount of catalyst carrier was placed in the mixed solution, and 0.5% polyvinyl alcohol was added. The container containing the catalyst carrier and the mixed liquid was placed in an ultrasonic bath for the first soaking for 48 hours. The carrier, which was saturated with liquid, was then placed in a vacuum drying oven at 180°C for 8 hours to obtain the powder for the second soaking. The remaining mixed liquid from the above process was poured into the powder that had been soaked and dried in the first soaking. This process was repeated until the mixed liquid had completely impregnated the powder.

[0113] The catalyst was added to a catalyst reduction and activation device at a reduction temperature of 390℃ for 45 min. The ratio of inert carrier gas to hydrogen in the reducing atmosphere was 2.5:1, and the hydrogen flow rate to catalyst mass ratio was 0.3 L / min:1.2 g. The catalyst was then fed into a primary reactor, where acetylene was introduced. The reaction temperature was 370℃ for 15 min, and the carbon source flow rate to catalyst mass ratio was 0.7 L / min:0.8 g. The carbon nanotube intermediate was then fed into a secondary reactor, where methane was introduced. The reaction temperature was 950℃ for 40 min, and the carbon source flow rate to catalyst mass ratio was 2 L / min:1.2 g. The reaction yielded an array of coarse tubes.

[0114] The prepared carbon nanotube arrays have an aspect ratio of (30–60):1 and a specific surface area of ​​85–105 m². 2 / g, powder resistivity is 55mΩ*cm.

[0115] Example 3

[0116] A certain amount of magnesium nitrate was dissolved in water, and an appropriate amount of citric acid monohydrate was added. After the citric acid was completely dissolved, a certain amount of ammonia was added to adjust the pH to 7.5. The mixed liquid was then placed in a vacuum drying oven at 230°C for expansion. After expansion, it was calcined in a muffle furnace at 600°C for 2 hours to obtain a light yellow and loose MgO powder.

[0117] Nickel nitrate, manganese nitrate, lanthanum nitrate, and calcium nitrate were mixed and dissolved in pure water at a molar ratio of 1:0.35:0.25:1.8. A certain amount of catalyst carrier was placed in the mixed solution, and 0.5% polyvinyl alcohol or polyethylene glycol was added. The container containing the catalyst carrier and the mixed liquid was placed in an ultrasonic bath for the first soaking for 48 hours. The carrier, which was saturated with liquid, was then removed and dried in a vacuum drying oven at 190°C for 8 hours to obtain the powder for the second soaking. The remaining mixed liquid from the above process was poured into the powder that had been soaked and dried in the first soaking. This process was repeated until all the mixed liquid had been used to impregnate the powder.

[0118] The catalyst was added to a catalyst reduction and activation device at a reduction temperature of 370℃ for 40 min. The ratio of inert carrier gas to hydrogen in the reducing atmosphere was 3.5:1, and the hydrogen flow rate to catalyst mass ratio was 0.35 L / min:1.2 g. The catalyst was then fed into a primary reactor, where acetylene was introduced. The reaction temperature was 420℃ for 20 min, and the carbon source flow rate to catalyst mass ratio was 0.6 L / min:1.5 g. The carbon nanotube intermediate was then fed into a secondary reactor, where methane was introduced. The reaction temperature was 850℃ for 35 min, and the carbon source flow rate to catalyst mass ratio was 1.5 L / min:1.5 g. The reaction yielded an array of coarse tubes.

[0119] The prepared carbon nanotube arrays have an aspect ratio of (20–40):1 and a specific surface area of ​​80–95 m². 2 / g, the powder resistivity is 56mΩ*cm.

[0120] Example 4

[0121] A certain amount of aluminum nitrate was dissolved in water, and an appropriate amount of citric acid monohydrate was added. After the citric acid was completely dissolved, a certain amount of ammonium carbonate was added to adjust the pH to 6.8. The mixed liquid was then placed in a vacuum drying oven at 240°C for expansion. After expansion, it was calcined in a muffle furnace at 590°C for 2 hours to obtain a light yellow and loose Al2O3 powder.

[0122] Nickel nitrate, manganese nitrate, lanthanum nitrate, and calcium nitrate were mixed and dissolved in pure water at a molar ratio of 1:0.25:0.2:1.5. A certain amount of catalyst carrier was placed in the mixed solution, and 0.8% polyvinyl alcohol or polyethylene glycol was added. The container containing the catalyst carrier and the mixed liquid was placed in an ultrasonic bath for the first soaking for 48 hours. The carrier, which was saturated with liquid, was then placed in a vacuum drying oven at 240°C for 8 hours to dry, which was used as the powder for the second soaking. The remaining mixed liquid from the above process was poured into the powder that had been soaked and dried in the first soaking. This process was repeated until the mixed liquid had completely impregnated the powder.

[0123] The catalyst was added to a catalyst reduction and activation device at a reduction temperature of 420℃ for 30 min. The ratio of inert carrier gas to hydrogen in the reducing atmosphere was 5:1, and the hydrogen flow rate to catalyst mass ratio was 0.1–0.5 L / min:2 g. The catalyst was then fed into a primary reactor, where acetylene was introduced. The reaction temperature was 540℃ for 30 min, and the carbon source flow rate to catalyst mass ratio was 1 L / min:2 g. The carbon nanotube intermediate was then fed into a secondary reactor, where methane was introduced. The reaction temperature was 1050℃ for 50 min, and the carbon source flow rate to catalyst mass ratio was 3 L / min:2 g. The reaction yielded an array of coarse tubes.

[0124] The prepared arrayed carbon nanotubes had an aspect ratio of (40–60):1 and a specific surface area of ​​84–110 m². 2 / g, the powder resistivity is 53mΩ*cm.

[0125] Example 5

[0126] A certain amount of magnesium nitrate was dissolved in water, and an appropriate amount of citric acid monohydrate was added. After the citric acid was completely dissolved, a certain amount of ammonia was added to adjust the pH to 7.8. The mixed liquid was then placed in a vacuum drying oven at 255°C for expansion. After expansion, it was calcined in a muffle furnace at 580°C for 2 hours to obtain a light yellow and loose MgO powder.

[0127] Nickel nitrate, manganese nitrate, lanthanum nitrate, and calcium nitrate were mixed and dissolved in pure water at a molar ratio of 1:0.5:0.4:2. A certain amount of catalyst carrier was placed in the mixed solution, and 2% polyvinyl alcohol or polyethylene glycol was added. The container containing the catalyst carrier and the mixed liquid was placed in an ultrasonic bath for the first soaking for 48 hours. The carrier, which was saturated with liquid, was then placed in a vacuum drying oven at 210°C for 8 hours to dry, which was used as the powder for the second soaking. The remaining mixed liquid from the above process was poured into the powder that had been soaked and dried in the first soaking. This process was repeated until all the mixed liquid had been used to impregnate the powder.

[0128] The catalyst was added to a catalyst reduction and activation device at a reduction temperature of 400℃ for 40 min. The ratio of inert carrier gas to hydrogen in the reducing atmosphere was 4:1, and the hydrogen flow rate to catalyst mass ratio was 0.45 L / min: 1.2 g. The catalyst was then fed into a primary reactor, where acetylene was introduced. The reaction temperature was 410℃ for 20 min, and the carbon source flow rate to catalyst mass ratio was 0.9 L / min: 2 g. The carbon nanotube intermediate was then fed into a secondary reactor, where methane was introduced. The reaction temperature was 800℃ for 40 min, and the carbon source flow rate to catalyst mass ratio was 3 L / min: 1.2 g. The reaction yielded an array of coarse tubes.

[0129] The prepared arrayed carbon nanotubes had an aspect ratio of (30–55):1 and a specific surface area of ​​85–100 m². 2 / g, the powder resistivity is 57mΩ*cm.

[0130] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing arrayed carbon nanotubes, characterized in that, The preparation method includes: Provide a nickel-based catalyst with a particle size within a preset range and a specific surface area within a preset specific surface area range; The nickel-based catalyst and the first carbon source atmosphere are introduced into the array carbon nanotube growth device and reacted at the first reaction temperature for the first reaction time to obtain the first reactant, wherein the first carbon source atmosphere is an alkyne. The first reactant and the second carbon source atmosphere are introduced into the carbon nanotube array growth device, and the reaction is carried out at the second reaction temperature for the second reaction time to obtain the carbon nanotube array. The second carbon source atmosphere is alkane. The carbon nanotube array has less entanglement and fewer defects. The nickel-based catalyst has a pore size of 0.2–2 μm, a particle size of 2–50 μm, and a specific surface area of ​​30–150 m². 3 / g.

2. The method for preparing arrayed carbon nanotubes according to claim 1, characterized in that, The provision of a nickel-based catalyst includes: Metal salts and foaming agents are mixed and dissolved according to a preset ratio, and the pH is adjusted to a preset value to obtain a mixed solution; The mixture is placed at a first preset temperature to react, yielding reactants; The reactants are calcined at a second preset temperature for a preset time to obtain a catalyst support; the catalyst support has a specific surface area of ​​50–230 m². 3 / g; The nickel-containing reagent and the catalyst support were placed under a first preset condition to react and obtain a preproduct. The preproduct was subjected to a reduction reaction under preset reduction conditions to obtain a nickel-based catalyst.

3. The method for preparing arrayed carbon nanotubes according to claim 2, characterized in that, The metal salt includes magnesium salt and / or aluminum salt, and the foaming agent includes citric acid. Correspondingly, the step of mixing and dissolving the metal salt and foaming agent according to a preset ratio, adjusting the pH to a preset value, and obtaining a mixed solution includes: Magnesium salts and / or aluminum salts are mixed and dissolved with citric acid in a preset ratio, and the pH is adjusted to the preset value to obtain a mixed solution.

4. The method for preparing arrayed carbon nanotubes according to claim 2, characterized in that, The step of placing the nickel-containing reagent and the catalyst support under a first preset condition to react and obtain a preproduct includes: The nickel-containing reagent and reaction aid are mixed and dissolved according to a preset molar ratio, and a dispersant is added to obtain a mixture; The catalyst support is added to the mixture, and an impregnation operation is performed under a second preset condition. The impregnated catalyst support is removed and subjected to solid-liquid separation to obtain primary impregnated powder. The above impregnation operation is repeated on the once-impregnated powder to obtain a pre-product.

5. The method for preparing arrayed carbon nanotubes according to claim 4, characterized in that, The nickel-containing reagent includes a nickel salt, the reaction aid includes a calcium salt, and the dispersant includes polyvinyl alcohol. Correspondingly, the step of mixing and dissolving the nickel-containing reagent and the reaction aid at a preset molar ratio, adding the dispersant, and obtaining a mixture includes: Nickel salt and calcium salt are mixed and dissolved according to a preset molar ratio, and polyvinyl alcohol is added to obtain a mixture.

6. The method for preparing arrayed carbon nanotubes according to claim 4, characterized in that, The step of adding the catalyst support to the mixture and performing an impregnation operation under a second preset condition includes: The catalyst support is added to the mixture, and an impregnation operation is performed under ultrasonic conditions. The process of removing the impregnated catalyst support and performing solid-liquid separation to obtain primary impregnated powder includes: The impregnated catalyst support is removed and dried at a third preset temperature to obtain a first-impregnated powder.

7. The method for preparing arrayed carbon nanotubes according to claim 4, characterized in that, The process of repeatedly performing the above impregnation operation on the once-impregnated powder to obtain a pre-product includes: The primary impregnated powder is mixed with the remaining liquid in the mixture and placed in an ultrasonic environment for a preset time. The impregnated powder is then removed and dried to obtain the secondary impregnated powder. Repeat the above impregnation operation until the mixture is completely impregnated to obtain the pre-product.

8. The method for preparing arrayed carbon nanotubes according to claim 1, characterized in that, The first carbon source atmosphere is acetylene; the second carbon source atmosphere is methane.

9. An array of carbon nanotubes, characterized in that, The arrayed carbon nanotubes are prepared using the method described in any one of claims 1 to 8.

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