CN114570380B

CN114570380B - Catalyst for growing ultra-high specific surface area and small wall carbon nano tube and application thereof

Info

Publication number: CN114570380B
Application number: CN202210189995.5A
Authority: CN
Inventors: 李卫力; 张新杰
Original assignee: Nori Shenzhen New Technology Co ltd
Current assignee: Nori Shenzhen New Technology Co ltd
Priority date: 2022-02-28
Filing date: 2022-02-28
Publication date: 2024-07-23
Anticipated expiration: 2042-02-28
Also published as: CN114570380A

Abstract

The application discloses a catalyst for growing a carbon nano tube with an ultrahigh specific surface area and a small wall and application thereof, and provides a preparation method of the carbon nano tube growth catalyst, which comprises the following steps: preparing a precursor solution from an active metal precursor, an inactive metal precursor and a carrier precursor; preparing a precipitant and a carboxylic acid polymer into a precipitant solution; and mixing the precursor solution and the precipitant solution, performing precipitation reaction, and collecting the precipitate to obtain the carbon nanotube growth catalyst. According to the scheme, the medium-activity metal precursor and the non-activity metal precursor are quickly complexed at the moment of contacting with the carboxylic acid polymer and are quickly precipitated under the action of the precipitator, so that a small-size and uniform dispersion state is formed, the final catalyst has smaller size, more uniform distribution and higher stability, and the carbon source can be catalyzed to deposit and form the few-wall carbon nano tube with higher specific surface area.

Description

Catalyst for growing ultra-high specific surface area and small wall carbon nano tube and application thereof

Technical Field

The application relates to the technical field of carbon nanotubes, in particular to a catalyst for growing a carbon nanotube with ultrahigh specific surface area and few walls and application thereof.

Background

Carbon Nanotubes (CNTs) are one-dimensional nanocarbon materials of hollow tubular structure, composed of carbon atoms arranged in hexagonal lattice, having a diameter of about 1 to 100nm, and having a high aspect ratio. In theory, carbon nanotubes have superior tensile strength, excellent thermal conductivity, excellent electrical conductivity and chemical stability. Due to its excellent physical and chemical properties, CNT has demonstrated potential for applications in composite materials, new energy, aerospace, biotechnology, electronics, semiconductors, etc., and has been widely and deeply studied. Over the years of development, CNTs have achieved commercial use in conductive plastics and battery conductive additives.

The synthesis method of the CNTs mainly comprises an arc discharge method, a laser evaporation method and a chemical vapor deposition method. In contrast, the chemical vapor deposition method is a main process for producing large-tonnage carbon nanotubes, and the chemical vapor deposition method specifically comprises the following steps: organic small molecules (such as ethylene, propylene, ethanol and the like) are catalyzed by a transition metal catalyst under the high temperature condition, and solid carbon nano tubes, hydrogen and the like are deposited by pyrolysis.

CNTs can be classified into three types according to the number of tube walls: single-walled CNTs having a diameter of about 1 nm; double-walled CNTs having a diameter of about 1.4-3 nm; and multi-wall CNTs having a diameter of about 5 to 100 nm. In the multi-wall CNT synthesis process, there is a problem in that as the number of multi-wall carbon nanotubes increases, the proportion of disordered graphite increases, resulting in degradation of the quality of the multi-wall carbon nanotubes. For this reason, efforts have been made in the industry to reduce the number of walls of multi-wall CNTs and to increase their specific surface area. Therefore, few-walled CNTs are becoming more and more favored in the industry, and the gap of the few-walled carbon nanotube products with high specific surface areas on the market is also larger. The reason for this is that the requirement of the small-wall CNT on the catalyst is higher, and the catalyst has an important influence on the growth and structure control of the CNT from the viewpoint of the preparation process of the chemical vapor deposition, so that it is necessary to provide a catalyst capable of growing the ultra-high specific surface area small-wall carbon nanotube.

Disclosure of Invention

The present application aims to solve at least one of the technical problems existing in the prior art. Therefore, the application provides a catalyst for growing the carbon nano tube with the ultrahigh specific surface area and the small wall and the application thereof.

In a first aspect of the present application, there is provided a method for preparing a carbon nanotube growth catalyst, the method comprising the steps of:

preparing a precursor solution from an active metal precursor, an inactive metal precursor and a carrier precursor;

Simultaneously contacting the precursor solution with a precipitator and a carboxylic acid polymer to perform precipitation reaction, and collecting the precipitate to obtain a carbon nano tube growth catalyst;

wherein, the active metal element of the active metal precursor is selected from at least one of Fe, co and Ni;

the inactive metal element of the inactive metal precursor is selected from at least one of Mo, V, W, cr;

the carrier element of the carrier precursor is at least one of Al and Mg.

The preparation method provided by the embodiment of the application has at least the following beneficial effects:

The solution separates the carboxylic acid polymer used for complexation from the metal precursor, and concurrent instantaneous coprecipitation occurs while mixing, i.e. the active metal precursor and the inactive metal precursor realize rapid complexation at the moment of contact with the carboxylic acid polymer and precipitate rapidly under the action of the precipitant, thereby forming a small-sized, uniform dispersion state, so that the final catalyst has smaller size, more uniform distribution and higher stability, and can catalyze carbon source deposition to form the small-wall carbon nanotubes with higher specific surface area.

Wherein, the simultaneous contact of the precursor solution with the precipitant and the carboxylic acid polymer means that the contact of the carboxylic acid polymer and the precipitant with the precursor system in the precursor solution does not form a specific sequence in a macroscopic sense, for example, the carboxylic acid polymer and the precipitant can be prepared into a reaction solution first and then mixed with the precursor solution; the three can be mixed simultaneously, so that the concurrent instantaneous coprecipitation can be ensured to occur at the same time of mixing.

It can be appreciated that in order to allow the active metal precursor, the inactive metal precursor, and the precipitant to complex and precipitate more rapidly, a slow drop-in, with vigorous stirring, manner may be employed during mixing so that the two solutions can achieve rapid complex and precipitation at the instant of meeting, forming uniform small particles.

The precipitant in the above reaction may be any precipitant known in the art that can cause precipitation of metal cations in the precursor solution, such as an alkaline solution. It will be appreciated that the precipitant solution preferably does not contain any metal ions in order not to affect the composition of the catalyst formed by the precipitation reaction.

The active metal precursor, the inactive metal precursor, and the carrier precursor refer to soluble components, such as soluble salts, including but not limited to fluoride salts, chloride salts, nitrate salts, sulfate salts, and the like, respectively, containing an active metal element, an inactive metal element, and a carrier element.

In some embodiments of the application, the active metal elements of the active metal precursor include Fe and Co.

In some embodiments of the application, the inactive metallic element of the inactive metallic precursor comprises at least one of Mo, V, and W.

In some embodiments of the present application, the support element of the support precursor is at least one of Al and Mg, and the support component formed is at least one of Al ₂O₃, mgO.

In some embodiments of the application, the mixing (dropping) rate of the precursor solution and other reaction materials and the concentration of the active metal precursor, inactive metal precursor, precipitant, complexing agent in the solution are controlled during the mixing reaction so that the pH of the system during the mixing reaction is about 8.

In some embodiments of the application, the carboxylic acid polymer is an optional complexing agent that can be used to complex with the reactive metal precursor. The carboxylic acid polymer is used as a complexing agent, the special chain structure of the carboxylic acid polymer is used for promoting the dispersion of active metal and inactive metal in the reaction process, and finally the specific surface area of the catalyst for catalyzing and growing the carbon nano tube is improved.

In some embodiments of the present application, the monomer of the carboxylic acid polymer is selected from at least one of acrylic acid, maleic acid, itaconic acid. The complexing action of the carboxylic acid polymer containing the monomer can lead the dispersion of the active metal to be more uniform when the carboxylic acid polymer is complexed with metal cations in the precursor.

In some embodiments of the application, the carboxylic acid polymer is a homopolymer, copolymer, or mixture. The mixture includes, but is not limited to, a mixture of at least two homopolymers, a mixture of at least two copolymers, a mixture of at least one homopolymer and at least one copolymer. Such as homopolymers of monomers such as acrylic acid, maleic acid, itaconic acid, and the like, or copolymers comprising at least one of the monomers in the composition, or mixtures comprising the foregoing homopolymers and/or copolymers.

In some embodiments of the application, the carboxylic acid polymer is at least one of polyacrylic acid, polymaleic acid, acrylic acid maleic acid copolymer.

In some embodiments of the application, the precipitant is selected from at least one of ammonium carbonate, ammonium bicarbonate, ammonia, urea.

In some embodiments of the application, the molar ratio of active metal element to carrier element is (0.5 to 0.65): 1. the low content of active metal elements can lead to poor activity of the prepared catalyst, and the growth rate of the carbon nano tube which is catalyzed and grown is low. If the content of the active metal element is too high, the active metal particles are larger, so that carbon nanotubes with large wall numbers and large tube diameters are grown.

In some embodiments of the present application, the molar ratio of active metal element to inactive metal element is (10 to 20): 1. the inactive metal in the precursor plays a role of physical barrier, prevents active metal particles from agglomerating and growing up under the high temperature condition of catalysis or roasting reduction before catalysis, and prevents the growth of the carbon nano tube with the ultrahigh specific surface area and the small wall.

In some embodiments of the present application, the active metal element of the active metal precursor includes Fe and Co, the inactive metal element of the inactive metal precursor includes at least one of Mo, V, and W, the carrier element of the carrier precursor is at least one of Al and Mg, and the molar ratio of the active metal element to the carrier element is (0.5 to 0.65): 1, the mol ratio of the active metal element to the inactive metal element is (10-20): 1.

In some embodiments of the application, the molar ratio of Fe to Co is 1: (1 to 100), preferably 1: (1-10), 1: (1-5).

It is understood that the precursor, the complexing agent and the precipitant react to form hydroxide directly, and the metal hydroxide may be calcined and reduced to form the mixture or alloy of simple substances of metal to participate in the catalytic reaction under the high temperature condition of chemical vapor deposition in consideration of the chemical vapor deposition process of preparing the carbon nanotubes. Thus, the step of calcination reduction thereof may be omitted or retained during the preparation of the catalyst. If the step of roasting reduction is required, the roasting can be carried out at 400-800 ℃, and further the roasting can be carried out at 400-700 ℃, 500-700 ℃ and 600-700 ℃.

In some embodiments of the application, the precipitate is collected by filtration and then dried, preferably at a temperature of 80 to 200 ℃, further at 120 to 180 ℃; the drying time is 6-24 h.

In some embodiments of the application, the precursor solution and the precipitant solution are respectively and simultaneously dripped into the reaction vessel at a constant speed, and the precursor solution and the precipitant solution are stirred at a high speed, so that the precursor solution and the precipitant solution are rapidly and uniformly mixed to generate a precipitation reaction.

In some embodiments of the present application, the stirring speed of the high-speed stirring is 300rpm or more, preferably 600rpm or more, further 1000rpm or more, 1500rpm or more.

In a second aspect of the present application, there is provided a carbon nanotube growth catalyst prepared by the aforementioned preparation method.

In a third aspect of the present application, there is provided a method for preparing carbon nanotubes, the method comprising the steps of: and (3) under the protective atmosphere, carrying out chemical vapor deposition on a carbon source under the action of a catalyst to obtain the carbon nanotube, wherein the catalyst is the carbon nanotube growth catalyst or the carbon nanotube growth catalyst prepared by the preparation method.

In some embodiments of the present application, the carbon source is an optional carbon source material capable of participating in the reaction in the form of a reaction gas, including but not limited to hydrocarbons that are in the gas phase at ambient temperature, such as at least one of methane, ethane, ethylene, propane, propylene, acetylene, and the like. In some preferred embodiments, the carbon source is ethylene or propylene. It will be appreciated that other commonly used carbon sources such as ethanol, acetone, dimethyl ether, etc. may also be used as the carbon source required in the preparation process.

In some embodiments of the application, the reaction temperature of the chemical vapor deposition is 600 to 700 ℃, preferably 600 to 660 ℃, further preferably 610 to 650 ℃,620 to 640 ℃; the reaction time of the chemical vapor deposition is 10 to 30 minutes, and more preferably 15 to 20 minutes.

In some embodiments of the present application, the protective atmosphere is an inert gas or nitrogen to protect the air, oxygen, etc. from affecting the growth of the carbon nanotubes.

In a fourth aspect of the present application, there is provided a carbon nanotube produced by the aforementioned production method. The carbon nano tube prepared by the method has a specific surface area of at least 430m ²/g, the aggregation form of the carbon nano tube is winding under observation, and the performances of the carbon nano tube in all aspects are more excellent based on the high specific surface area of the carbon nano tube. Further, by adjusting the technological parameters, the specific surface area of the prepared carbon nano tube can reach more than 450m ²/g, more than 500m ²/g and more than 550m ²/g.

In a fifth aspect of the application, there is provided a composition comprising the aforementioned carbon nanotubes. The composition is formed by using the carbon nano tube as a main raw material or an additive component, and comprises, but is not limited to, a polymer conductive additive, a lithium battery positive electrode conductive agent, a conductive paste, other additives or lubricants and the like.

The application aims to provide a growth catalyst of a few-wall carbon nano tube, which comprises an active component, an inactive component and a carrier component. The catalyst can be used for producing the winding type few-wall carbon nano tube with ultra-high specific surface area (for example, more than 550m ²/g) at a higher multiplying power by matching with optimized process conditions, has excellent catalytic growth effect and has a larger application prospect in the preparation of the carbon nano tube.

Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.

Drawings

FIG. 1 shows the process of nitrogen gas in example 1: ethylene=2: 1, a scanning electron microscope image of carbon nanotubes grown at 640℃for 10 minutes.

Fig. 2 and 3 show the nitrogen gas in example 1 of the present application: ethylene=2: 1, a transmission electron microscope image of a carbon nanotube grown at 640℃for 10 minutes.

Detailed Description

The conception and the technical effects produced by the present application will be clearly and completely described in conjunction with the embodiments below to fully understand the objects, features and effects of the present application. It is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments, and that other embodiments obtained by those skilled in the art without inventive effort are within the scope of the present application based on the embodiments of the present application.

The following detailed description of embodiments of the application is exemplary and is provided merely to illustrate the application and is not to be construed as limiting the application.

In the description of the present application, the meaning of a number is one or more, the meaning of a number is two or more, and greater than, less than, exceeding, etc. are understood to exclude the present number, and the meaning of a number is understood to include the present number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated. About is understood to mean floating up and down within a range of + -20%, + -15%, + -10%, + -8%, + -5%, + -3%, + -2%, + -1%, + -0.5%, + -0.2%, + -0.1% of the dot value.

In the description of the present application, the descriptions of the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

In the following examples, "wrap-around" carbon nanotubes refer to the secondary aggregation state of carbon nanotubes, which can be confirmed by Scanning Electron Microscopy (SEM).

The yields of the catalyst and the growth process are expressed in "multiplying power".

Multiplying power = (total weight of CNT after reaction-weight of catalyst before reaction)/weight of catalyst before reaction

Example 1

The embodiment provides a carbon nanotube growth catalyst, and the preparation method thereof comprises the following steps:

Fe (NO ₃)₃·9H₂O、Co(NO₃)₂·6H₂ O and Al (NO ₃)₃·9H₂ O are respectively dissolved in deionized water to prepare solutions with the corresponding metal element concentration of 1.5mol/Kg for standby, NH ₄)₆Mo₇O₂₄·4H₂ O is dissolved in deionized water to prepare solutions with the Mo element concentration of 0.15mol/Kg for standby, and NH ₄)₂CO₃ is dissolved in deionized water to prepare solutions with the metal element concentration of 3mol/Kg for standby.

The molar ratio of the elements is as follows: co: mo: al=1: 1:0.1:3.2, respectively weighing and mixing 25g, 25g and 80g of Fe, co, mo, al precursor solutions to obtain the precursor solutions.

190G (NH ₄)₂CO₃ solution) of acrylic acid maleic acid copolymer with the mass content of 49% is added and evenly mixed to obtain a precipitant solution.

200ML of deionized water was added to a 2L three-necked flask, and the precursor solution and the precipitant solution were simultaneously dropped while maintaining vigorous stirring. After the dripping is finished, stirring is continued for half an hour, and the final pH value is measured to be 8-8.5 by using pH test paper.

Filtering to obtain precipitate (note that a large amount of deionized water is not needed after filtering), drying in a drying oven at 150 ℃ for 12h, and grinding the dried product into fine powder to obtain the low-wall carbon nanotube growth catalyst.

The embodiment also provides a carbon nanotube, and the preparation method of the carbon nanotube comprises the following steps:

Carbon nanotube growth experiments were performed in a horizontal fixed bed quartz reactor. And (3) uniformly placing the prepared catalyst for growing the carbon nano tubes with the small wall thickness in a quartz boat, and pushing the quartz boat into a constant temperature area of a tube furnace. The temperature was raised to the reaction temperature under a nitrogen atmosphere, and then ethylene was introduced as a carbon source. After a certain time of reaction, the ethylene is turned off, the temperature is reduced to room temperature under the nitrogen atmosphere, the carbon nano tube is taken out, the weight is weighed, the multiplying power is calculated, and the specific surface area is measured by a BET method.

The results are shown in tables 1 and 2, which are nitrogen during the reaction: ethylene=1: 1. nitrogen gas: ethylene=2: test results at 1.

Table 1. Nitrogen: ethylene=1: carbon nanotube growth results for different experimental parameters under condition 1

Table 2. Nitrogen: ethylene=2: carbon nanotube growth results for different experimental parameters under condition 1

Experiment number	Reaction temperature/. Degree.C	Reaction time/min	Production multiplying power	CNT specific surface area/(m ²/g)
					1	600	10	3.5	496
2	620	10	6.5	546
					3	640	10	10	565
4	660	10	18	523

As can be seen from the measurement results in Table 1 and Table 2, the specific surface area of the carbon nanotubes prepared in the examples of the present application is above 430m ²/g, and further above 500m ²/g can be achieved by adjusting the reaction parameters. While under nitrogen: ethylene=2: 1, and a reaction temperature of about 640 ℃, a small-wall CNT having a specific surface area of more than 550m ²/g can be obtained. On the other hand, comparing the growth rate thereof, it was found that the growth rate of CNT gradually increased with increasing temperature.

Referring to fig. 1, a scanning electron microscope image of a carbon nanotube grown for 10 minutes at a reaction temperature of 640 ℃ in table 2 shows that the carbon nanotube prepared by the embodiment of the application has an obvious secondary aggregation morphology of winding. Referring to fig. 2 and 3, there are transmission electron microscopic images of carbon nanotubes grown at a reaction temperature of 640 ℃ for 10 minutes in table 2, and it can be seen from the images that the carbon nanotubes prepared by this method have diameters of approximately 3nm or less, which are typical of few-wall carbon nanotubes.

Further analyzed as follows, the specific surface area of CNT and the number of tube walls thereof have a direct relationship with tube diameter, and the smaller the tube walls, the larger the specific surface area. The number of the tube walls and the tube diameter are influenced by factors such as the particle size of the active component particles in the growth catalyst, in general, the smaller the particle size of the active component particles is, the smaller the number of the obtained CNT walls is, the smaller the tube diameter is, and the larger the specific surface area of the carbon nanotube is. The initial particle size of the active component particles of the growing catalyst is determined by the catalyst preparation method, but the particle size of the active component particles can gradually grow up along with the progress of the reaction temperature at a higher reaction temperature, so that the number of walls is increased, the tube diameter is increased, and the catalyst is deactivated. Reducing the reaction temperature slows down the catalyst particle size, but the contradiction is that reducing the reaction temperature results in a slower CNT growth rate and reduced production efficiency.

In the embodiment of the application, the carbon nano tube growth condition is more proper through the optimization combination of the catalyst preparation method, and the small-wall CNT with the specific surface area exceeding 550m ²/g is successfully prepared.

Comparative example 1

The comparative example provides a carbon nanotube growth catalyst, the preparation method of which comprises the following steps:

Fe (NO ₃)₃·9H₂O、Co(NO₃)₂·6H₂ O and Al (NO ₃)₃·9H₂ O are respectively dissolved in deionized water to prepare 1.5mol/Kg solution for standby, NH ₄)₆Mo₇O₂₄·4H₂ O is dissolved in deionized water to prepare 0.15mol/Kg solution for standby, and NH ₄)₂CO₃ is dissolved in deionized water to prepare 3mol/Kg solution for standby.

The molar ratio of the elements is as follows: co: mo: al=1: 1:0.1:3.2, respectively weighing and mixing 25g, 25g and 80g of Fe, co, mo, al precursor solution, then adding 14g of acrylic acid maleic acid copolymer with the mass content of 49%, and uniformly mixing to obtain the precursor solution.

190G (NH ₄)₂CO₃ solution) were taken as precipitant solution.

And (3) filtering to obtain a precipitate, drying the precipitate in a drying oven at 150 ℃ for 12 hours, and grinding the dried product into fine powder to obtain the small-wall-thickness carbon nano tube growth catalyst.

The comparative example also provides a carbon nanotube, which is prepared by the following steps:

Carbon nanotube growth experiments were performed in a horizontal fixed bed quartz reactor. And (3) uniformly placing the small-wall carbon nanotube growth catalyst prepared in the comparative example in a quartz boat, and pushing the quartz boat into a constant temperature area of a tube furnace. The temperature was raised to the reaction temperature under a nitrogen atmosphere, and then ethylene was introduced as a carbon source. After a certain time of reaction, the ethylene is turned off, the temperature is reduced to room temperature under the nitrogen atmosphere, the carbon nano tube is taken out, the weight is weighed, the multiplying power is calculated, and the specific surface area is measured by a BET method.

The results are shown in Table 3, which are nitrogen during the reaction: ethylene=2: test results at 1.

TABLE 3 carbon nanotube growth results for different experimental parameters of comparative example 1

Experiment number	Reaction temperature/. Degree.C	Reaction time/min	Production multiplying power	CNT specific surface area/(m ²/g)
					1	600	10	4.1	416
2	620	10	7	423
					3	640	10	15	424
4	660	10	19	429

Comparing the results in table 3 of comparative example 1 with the results in table 2 of example 1, the catalyst of comparative example 1 was prepared by directly adding the acrylic acid maleic acid copolymer as a complexing agent to a metal precursor solution, complexing the precursor with the complexing agent in the reaction, and then precipitating with a precipitating agent, the specific surface area of the finally obtained CNT was lower than 450m ²/g, and compared with example 1, which was much larger than 450m ²/g under the same conditions, up to 565m ²/g, which is a very great improvement compared with comparative example 1.

Example 2

This example provides a method for preparing a carbon nanotube growth catalyst, which is different from example 1 in that aluminum nitrate is replaced with equimolar magnesium nitrate.

Example 3

This example provides a method for preparing a carbon nanotube growth catalyst, which is different from example 1 in that ammonium molybdate is replaced with equimolar ammonium tungstate.

Example 4

The present embodiment provides a method for preparing a carbon nanotube growth catalyst, which is different from embodiment 1 in that Fe: co: mo: the molar ratio of Al is 1:1:0.2:4.

The carbon nanotube catalysts prepared in examples 2 to 4 can achieve the effect of growing the ultra-high specific surface area and small wall carbon nanotubes similar to example 1, and will not be described here again.

The present application has been described in detail with reference to the embodiments, but the present application is not limited to the embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application. Furthermore, embodiments of the application and features of the embodiments may be combined with each other without conflict.

Claims

1. The preparation method of the carbon nano tube growth catalyst is characterized by comprising the following steps:

Simultaneously contacting the precursor solution with a precipitator and a carboxylic acid polymer to perform precipitation reaction, and collecting precipitation to obtain the carbon nanotube growth catalyst;

Wherein the active metal element of the active metal precursor is selected from at least one of Fe, co and Ni;

the inactive metal element of the inactive metal precursor is at least one selected from Mo, V, W, cr;

the carrier element of the carrier precursor is at least one of Al, mg and Ti.

2. The method according to claim 1, wherein the monomer of the carboxylic acid polymer is at least one selected from the group consisting of acrylic acid, maleic acid, and itaconic acid.

3. The method of claim 1, wherein the carboxylic acid polymer is a homopolymer, copolymer, or mixture.

4. The method according to claim 1, wherein the carboxylic acid polymer is at least one of polyacrylic acid, polymaleic acid, and acrylic acid-maleic acid copolymer.

5. The method according to any one of claims 1 to 4, wherein the precipitating agent is at least one selected from the group consisting of ammonium carbonate, ammonium bicarbonate, aqueous ammonia, and urea.

6. The method according to any one of claims 1 to 4, wherein the molar ratio of the active metal element to the carrier element is (0.5 to 0.65): 1.

7. The production method according to any one of claims 1 to 4, wherein a molar ratio of the active metal element to the inactive metal element is (10 to 20): 1.

8. A carbon nanotube growth catalyst, characterized by being produced by the production method according to any one of claims 1 to 7.

9. The preparation method of the carbon nano tube is characterized by comprising the following steps: and (3) carrying out chemical vapor deposition on a carbon source under the action of a catalyst in a protective atmosphere to obtain the carbon nanotube, wherein the catalyst is the carbon nanotube growth catalyst in claim 8 or prepared by adopting the preparation method in any one of claims 1 to 7.

10. The method according to claim 9, wherein the chemical vapor deposition is performed at a reaction temperature of 600 to 700 ℃ for a reaction time of 10 to 30 minutes.

11. The method according to claim 10, wherein the reaction temperature of the chemical vapor deposition is 610 to 650 ℃.

12. The method of claim 11, wherein the chemical vapor deposition reaction temperature is 620-640 ℃.

13. Carbon nanotube, characterized by being produced by the production method according to any one of claims 9 to 12.

14. A composition comprising the carbon nanotube of claim 13.