A preparation method to increase carbon nanotube yield

Abstract

This invention provides a method for increasing carbon nanotube yield, characterized by comprising a heated bed, a container, substance A, and catalyst B for low-cost carbon nanotube production. Substance A and catalyst B are placed in the heated bed. Under certain temperature, gas source, and reactant conditions, catalyst B can produce carbon nanotubes on its own. Substance A is prepared at low cost and cannot produce carbon nanotubes on its own; however, under the activation of catalyst B, substance A can produce carbon nanotubes with similar quality and morphology. This invention solves the problems of high catalyst preparation cost and low carbon nanotube yield in prior art.

Description

Technical Field

[0001] This invention relates to the fields of chemical engineering and materials, and in particular to a method for increasing the yield of carbon nanotubes. Background Art

[0002] Carbon nanotubes have become a star material in modern materials science due to their unique properties and broad application prospects. They possess extremely high strength and toughness, excellent electrical and thermal conductivity, and superior chemical stability. These properties enable carbon nanotubes to demonstrate enormous potential in various fields such as electronic devices, energy storage, composite materials, and biomedicine.

[0003] Various methods exist for preparing carbon nanotubes, primarily including arc discharge, laser ablation, chemical vapor deposition (CVD), and solid-state pyrolysis. Arc discharge involves activating an electric arc in a reaction vessel filled with inert gas, causing graphite to evaporate and generate carbon nanotubes. However, this method yields low-purity carbon nanotubes, often mixed with other products. CVD, as the main method for producing carbon nanotubes, decomposes gaseous hydrocarbons under the action of a catalyst, offering advantages such as high product purity and lower temperatures, leading to its widespread application. However, challenges remain regarding yield and cost. Currently, the main solution in existing technologies is to optimize catalyst preparation processes to reduce costs and increase yield rates. However, catalyst development has almost reached a bottleneck, making significant improvements difficult.

[0004] In conclusion, it is necessary and urgent to develop a preparation method that increases the yield of carbon nanotubes. Summary of the Invention

[0005] This invention provides a method for increasing the yield of carbon nanotubes, thereby addressing the problems of high catalyst preparation costs and low carbon nanotube yields in prior art.

[0006] To solve the above-mentioned technical problems, the present invention is implemented as follows:

[0007] This invention provides a method for increasing the yield of carbon nanotubes, characterized by comprising a heated bed, substance A, and catalyst B for low-cost improvement of carbon nanotube yield; substance A and catalyst B are placed in the heated bed, and at least one container or partition plate is used to support substance A and catalyst B; under certain temperature, gas source, and reactant conditions, catalyst B can prepare carbon nanotubes on its own, while substance A is prepared at low cost and cannot prepare carbon nanotubes on its own; however, under the activation of catalyst B, substance A can prepare carbon nanotubes with similar morphology and quality.

[0008] The heating bed, including a tubular furnace or a fluidized bed, is a heating device in which heat is supplied by electric current to bring the material inside the furnace tube to the required heating temperature. The catalyst in the tubular furnace is in a static state, and the gas flow is relatively stable, while the catalyst in the fluidized bed is in a suspended and rolling state, and the gas flow is more turbulent.

[0009] The substance A and catalyst B are placed in the tubular furnace, with the following placement methods: substance A is placed in the container, and a small amount of catalyst B is placed in a different container, with the two containers being adjacent; or substance A and a small amount of catalyst B are mixed and placed in the same container. Alternatively, carbon nanotubes can be prepared in the fluidized bed, with the following placement methods: substance A is placed on the separator plate, and a small amount of catalyst B is placed on separator plates of different layers; or substance A and a small amount of catalyst B are mixed and placed on the same separator plate.

[0010] In this embodiment of the invention, by preparing a large amount of the substance A and a small amount of the catalyst B, the preparation cost of the catalyst can be effectively reduced. Through the turbulent characteristics of the flow field vortex, the area above adjacent containers becomes a reflux region, meaning that the carbon molecules catalyzed by the catalyst B flow back to the substance A. Through the catalytic function of the catalyst B, the catalyzed carbon molecules are deposited onto the surfaces of the catalyst B and the substance A, thereby preparing a large number of carbon nanotubes. This embodiment of the invention solves the problems of high catalyst preparation cost and low carbon nanotube yield in the prior art. Attached Figure Description

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0012] Figure 1 This diagram illustrates that the heating bed in a method for increasing carbon nanotube yield provided in an embodiment of the present invention is a tube furnace;

[0013] Figure 2 This diagram illustrates that the heating bed in a method for increasing carbon nanotube yield provided in an embodiment of the present invention is a fluidized bed;

[0014] Figure 3 This is a simulation diagram showing adjacent and non-adjacent containers in a method for increasing carbon nanotube yield provided by an embodiment of the present invention, where the heating bed is a fixed bed.

[0015] Figure 4This shows SEM characterization images of the carbon nanotube products provided in the embodiments of the present invention.

[0016] In the diagram, 1 is the heated bed, 2 is ceramic boat 1, 3 is substance A, 4 is ceramic boat 2, 5 is catalyst B, 6 is the partition plate, and 7 is the separator. Detailed Implementation

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0018] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0019] See Figures 1 to 4 This invention provides a method for increasing the yield of carbon nanotubes, which solves the problems of high catalyst preparation cost and low carbon nanotube yield. The method includes a heated bed (1), substance A (3) and catalyst B (5). Substance A (3) and catalyst B (5) are in a mixed state or adjacent state. Under certain temperature, gas source and reactant conditions, carbon nanotubes are grown in both substance A (3) and catalyst B (5). Substance A (3) is prepared by ferric nitrate, aluminum nitrate and alumina ceramic balls in a protective gas environment.

[0020] In this embodiment of the invention, by preparing a large amount of the substance A and a small amount of the catalyst B, the preparation cost of the catalyst can be effectively reduced. Through the turbulent characteristics of the flow field vortex, the area above adjacent containers becomes the reflux region, which allows the carbon molecules catalyzed by the catalyst B to flow back to the substance A. Through the catalytic function of the catalyst B, the catalyzed carbon molecules are deposited onto the surfaces of the catalyst B and the substance A, thereby preparing a large number of carbon nanotubes. This embodiment of the invention solves the problems of high catalyst preparation cost and low carbon nanotube yield in the prior art.

[0021] Preferably, the heating bed (1) is a sealed pipe with heating function, including a fixed bed or a fluidized bed, with a maximum heat resistance temperature of 1200℃ and a heating rate of 1-20℃ / min.

[0022] Preferably, the heating bed (1) has an air inlet pipe at one end that enters the air source and an air outlet at the other end.

[0023] Preferably, the fluidized bed is composed of multiple partition plates (6) that can separate the substance A (3) and the catalyst B (5) into different partitions (7), but the gas source can pass through the partition plates (6) smoothly.

[0024] It should be noted that the ventilation holes of the partition plate (6) are small enough to prevent substances A (3) and catalyst B (5) from mixing into different partitions, and the fluidized bed includes, but is not limited to, a bed type in which the gas source enters from the bottom, and also includes a bed type in which the air inlet pipe extends from the top to the bottom of the fluidized bed.

[0025] Preferably, the substance A (3) and catalyst B (5) are contained in one container or two adjacent containers and placed in the fixed bed for reaction, or the substance A (3) and catalyst B (5) are contained in a fluidized bed for reaction.

[0026] It should be noted that the containers need to be adjacent. According to simulation calculations, if the containers are not adjacent, their own backflow fields will be formed above them. That is, the process of carbon molecules catalyzed by catalyst B (5) flowing to the substance A (3) cannot be realized, and carbon nanotubes cannot be prepared.

[0027] It should be noted that the backflow field is the flow field formed when gas flows against the flow direction.

[0028] Preferably, the container includes a porcelain boat or vessel that can hold a certain volume of liquid, and the container can maintain contact with the ambient gas and at least maintain the same heat resistance temperature as the heating bed (1).

[0029] It should be noted that the container can also hold substance A (3) and catalyst B (5), and is the place for the growth and preparation of carbon nanotubes.

[0030] Preferably, the catalyst B(5) is a transition metal oxide particle, wherein the oxide element includes at least iron, cobalt, aluminum, and molybdenum, and the catalyst B(5) grows into the carbon nanotube when reacting alone.

[0031] It should be noted that the catalyst B (5) can activate the activity of the substance A (3) under certain temperature, gas source and reactant conditions, so as to realize the deposition process of the catalyzed carbon molecules.

[0032] Preferably, the substance A (3) is an alumina ceramic ball coated with iron and aluminum metals, and the substance A (3) does not grow into the carbon nanotube when reacting alone.

[0033] Preferably, the low-cost firing of substance A(3) comprises the following steps:

[0034] Step (1): Add ferric nitrate and aluminum nitrate to deionized water and stir to prepare a mixed solution. Then weigh the alumina ceramic balls and immerse them in the mixed solution.

[0035] Step (2): Place the mixed solution prepared in step (1) and the alumina ceramic balls in the container and place them in the fixed bed. Set a suitable evaporation temperature and heat from room temperature to the catalyst solution until it is evaporated. The entire process is purged with the protective gas.

[0036] Step (3): After waiting for the temperature to drop, take out the container to obtain the alumina ceramic ball coated with iron and aluminum metal, i.e., substance A (3).

[0037] It should be noted that the suitable evaporation temperature is between 200-1000℃.

[0038] It should be noted that after evaporating the mixed solution to dryness, it is necessary to cool it down in the atmosphere of the protective gas until it reaches room temperature.

[0039] Preferably, the specific temperature is between 600-1000℃, the gas source includes a reducing gas, a protective gas, and a carbon source, the reducing gas includes hydrogen, the protective gas includes nitrogen or argon, and the carbon source includes propylene or methane.

[0040] It should be noted that the process of preparing the carbon nanotubes requires first passing nitrogen gas until a certain temperature is reached, then passing hydrogen gas to reduce catalyst B (5), and then passing the carbon source to prepare the carbon nanotubes.

Claims

1. A method for increasing the yield of carbon nanotubes, characterized in that: The method includes using a heated bed (1) containing a substance A (3) and a catalyst B (5). The substance A (3) and the catalyst B (5) are in a mixed state or adjacent state and are placed in containers respectively. Under certain temperature, gas source and reactant conditions, carbon nanotubes are grown in both the substance A (3) and the catalyst B (5). The substance A (3) is prepared by using ferric nitrate, aluminum nitrate and alumina ceramic balls in a protective gas environment; The substance A (3) is an alumina ceramic ball coated with iron and aluminum metals, and the carbon nanotubes do not grow when the substance A (3) reacts alone; The heating bed (1) is a fluidized bed.

2. The preparation method for increasing carbon nanotube yield according to claim 1, characterized in that: The heating bed (1) has a maximum heat resistance temperature of 1200 ℃ and a heating rate of 1-20 ℃ / min. The heating bed (1) has an air inlet pipe at one end that enters the gas source and a gas outlet at the other end.

3. The preparation method for increasing carbon nanotube yield according to claim 2, characterized in that: The fluidized bed has multiple partition plates (6) that can separate substance A (3) and catalyst B (5) into different partitions (7), but the gas source can pass smoothly through the partition plates (6).

4. The preparation method for increasing carbon nanotube yield according to claim 1, characterized in that: The substance A (3) and the catalyst B (5) are contained in one of the containers or two adjacent containers and placed on the heated bed (1) for reaction.

5. The preparation method for increasing carbon nanotube yield according to claim 4, characterized in that: The container includes a porcelain boat or a vessel, which can hold a certain volume of liquid. The container can be in contact with the ambient gas and at least maintain the same heat resistance temperature as the heating bed (1).

6. The preparation method for increasing carbon nanotube yield according to claim 1, characterized in that: The catalyst B (5) is a transition metal oxide particle; the transition metal oxide element includes at least iron, cobalt and molybdenum, and the carbon nanotubes are grown when the catalyst B (5) reacts alone.

7. The method for increasing carbon nanotube yield according to claim 1, characterized in that: The preparation of substance A (3) includes the following steps: Step 1): Add the ferric nitrate and aluminum nitrate to deionized water and stir to prepare a mixed solution; then weigh the alumina ceramic balls and immerse them in the mixed solution; Step 2): The mixed solution prepared in Step 1) and the alumina ceramic balls are placed in the container and placed in the heating bed (1). A suitable evaporation temperature is set, and the mixture is heated from room temperature to dryness. The entire process is purged with protective gas. Step 3): After waiting for the temperature to drop, remove the container to obtain an alumina ceramic ball coated with iron and aluminum metal, namely substance A (3).

8. The preparation method for increasing carbon nanotube yield according to claim 1, characterized in that: The specified temperature is 600-1000 ℃, and the gas source includes a reducing gas, a protective gas, and a carbon source; the reducing gas includes hydrogen; the protective gas includes nitrogen or argon; and the carbon source includes propylene or methane.

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