An aerosol-assisted system and method for preparing single-walled carbon nanotubes

Abstract

The present invention provides an aerosol-assisted single-walled carbon nanotube preparation system and method, which relates to the field of single-walled carbon nanotube preparation. The system includes a catalyst atomization unit, a catalyst screening unit, a vapor-phase chemical deposition reaction unit, and a collection unit with interconnected inner cavities; the catalyst screening unit is arranged at the connection between the catalyst atomization unit and the vapor-phase chemical deposition reaction unit, and the collection unit is connected to the tail end of the vapor-phase chemical deposition reaction unit; the outer diameter of the catalyst screening unit is smaller than the outer diameters of the catalyst atomization unit and the vapor-phase chemical deposition reaction unit. The present invention uses aerosol atomization technology to pre-atomize the liquid catalyst and then perform screening treatment, which is easier to fully vaporize to obtain small-sized catalyst particles with uniform particles, effectively inhibits the formation of large catalyst particles, effectively controls the growth diameter of single-walled carbon nanotubes, reduces the formation of amorphous carbon, and thus can improve the quality and purity of single-walled carbon nanotubes.

Description

Technical Field

[0001] The present invention relates to the field of single-walled carbon nanotube preparation, and particularly to an aerosol-assisted single-walled carbon nanotube preparation system and method. Background Art

[0002] Single-walled carbon nanotubes (SWCNTs) are one-dimensional nanomaterials with a radial size on the nanometer scale and an axial size on the micrometer scale. Their structure can be regarded as a one-dimensional cylindrical nanomaterial formed by rolling up two-dimensional graphene, and they have unique physical structures and chemical properties. The diameter of single-walled carbon nanotubes is 1-3 nm, showing excellent mechanical strength, thermal conductivity, and electrical conductivity, which makes single-walled carbon nanotubes have extensive application values in the fields of composite materials, electronic devices, and energy storage.

[0003] Existing single-walled carbon nanotube preparation technologies are often based on chemical vapor deposition. During the preparation process, it is difficult for catalyst droplets to be fully vaporized in the carrier gas, and large particle catalysts are easily formed, resulting in an increase in residual catalysts and amorphous carbon impurities in the product. These impurities will significantly reduce the purity and consistency of single-walled carbon nanotubes and affect their performance in many applications. In addition, the catalyst particles of traditional vapor-phase chemical deposition are not uniform enough, resulting in a large diameter difference in the prepared single-walled carbon nanotubes, further affecting the quality of single-walled carbon nanotubes.

[0004] In the prior art, by using the high energy and fast oscillation characteristics of high-frequency electromagnetic oscillation, the surface tension of catalyst droplets can be effectively broken, thereby realizing a smaller particle size distribution of catalyst particles. However, high-frequency electromagnetic oscillation equipment usually requires high-precision electromagnetic field control and stable power supply support, and the process control is difficult. Therefore, there is an urgent need for an efficient and low-cost single-walled carbon nanotube preparation method to achieve a narrower scale control of the catalyst particle size distribution and improve the yield and purity of single-walled carbon nanotubes. Summary of the Invention

[0005] To solve the above technical problems, the present invention aims to provide an aerosol-assisted single-walled carbon nanotube preparation system and method. The present invention mainly obtains uniform and fine catalyst particles through atomization and screening treatment, thereby improving the quality of single-walled carbon nanotubes.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides an aerosol-assisted single-walled carbon nanotube preparation system, including a catalyst atomization unit, a catalyst screening unit, a vapor-phase chemical deposition reaction unit, and a collection unit with interconnected inner cavities;

[0008] The catalyst screening unit is arranged at the connection between the catalyst atomization unit and the vapor-phase chemical deposition reaction unit, and the collection unit is connected to the tail end of the vapor-phase chemical deposition reaction unit;

[0009] The outer diameter of the catalyst screening unit is smaller than the outer diameters of the catalyst atomization unit and the vapor-phase chemical vapor deposition reaction unit.

[0010] Further, the catalyst atomization unit and the vapor-phase chemical vapor deposition reaction unit form a Venturi tube structure. The catalyst atomization unit includes an atomization chamber, which is composed of an integrally formed cylindrical inlet section and a tapered acceleration section. An atomizing nozzle and a carrier gas inlet are arranged in the middle of the inlet section of the atomization chamber. The carrier gas inlet is located below the atomizing nozzle. A vacuum valve is arranged on the side wall of the inlet section of the atomization chamber. The catalyst screening unit is arranged at the end of the tapered acceleration section. The vapor-phase chemical vapor deposition reaction unit includes a reaction chamber, and a gaseous carbon source inlet is arranged at the bottom of the side wall of the reaction chamber close to the catalyst screening unit.

[0011] Preferably, a thermocouple is arranged at the top of the reaction chamber.

[0012] Further, the collection unit includes a collection chamber, an exhaust port is arranged on the collection chamber, and a carbon nanotube collection membrane is arranged in the collection chamber.

[0013] Further, the catalyst screening unit includes a porous screen.

[0014] Preferably, the porous screen is a three-layer structure that fits tightly, and the pore diameter of the middle-layer porous screen is smaller than the pore diameters of the two outer-layer porous screens.

[0015] In a second aspect, the present invention provides a method for aerosol-assisted preparation of single-walled carbon nanotubes, which is realized by using the above-mentioned aerosol-assisted preparation system for single-walled carbon nanotubes. The specific steps include:

[0016] S1: First, connect a vacuum machine through the vacuum valve to evacuate the inside of the system, close the vacuum valve, and then introduce a carrier gas through the carrier gas inlet to remove air.

[0017] S2: Atomize the liquid catalyst through the atomizing nozzle, and bring the atomized catalyst into the catalyst screening unit through the carrier gas. The unatomized liquid droplets here will be intercepted by the porous screen and vaporized again. The fully vaporized catalyst enters the high-temperature vapor-phase chemical vapor deposition reaction unit. At the same time, the gaseous carbon source is sprayed into the vapor-phase chemical vapor deposition reaction unit through the gaseous carbon source inlet, and then single-walled carbon nanotubes are generated by cracking under the action of the catalyst.

[0018] S3: In the collection unit, the generated single-walled carbon nanotubes are intercepted and separated from the tail gas through the carbon nanotube collection membrane and collected as a solid product.

[0019] Further, the carrier gas is one of argon, nitrogen, and carbon dioxide.

[0020] Preferably, the carrier gas flow rate is controlled at 10 - 40 L / min, and the carbon source gas flow rate is controlled at 0 - 20 L / min.

[0021] Furthermore, the liquid catalyst is a mixed solution of a pre-prepared catalyst and a catalyst promoter. The catalyst is one or several of ferrocene, iron nitrate, iron carbonyl, cobaltocene, cobalt nitrate, nickelocene, and nickel nitrate; the catalyst promoter is one or several of sulfur, thiophene, methanethiol, and carbon disulfide. The solvent used for the mixed solution is one of methanol and ethanol.

[0022] Furthermore, the mass ratio of the solvent to the catalyst is 100:1, the mass ratio of the catalyst to the catalyst promoter is 50 - 100:1, and the reaction temperature in the chemical vapor deposition reaction unit is 1000 - 1500 °C.

[0023] Preferably, the mass ratio of the catalyst to the catalyst promoter is 100:1; the reaction temperature in the chemical vapor deposition reaction unit is 1280 °C.

[0024] Furthermore, the carbon source is one or several of methane, methanol, ethane, ethanol, propane, and propylene.

[0025] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0026] 1. In the aerosol-assisted single-walled carbon nanotube preparation system of the present invention, after the mixed solution of the catalyst and the catalyst promoter is atomized by the aerosol atomization technology, it is sent into the porous screen by the carrier gas for screening. The fully atomized small-sized droplets directly pass through the porous screen and enter the chemical vapor deposition reaction unit, while the large-sized droplets that are not fully atomized are intercepted by the porous screen. The large-sized droplets contact the high-temperature porous screen, quickly absorb heat and vaporize secondary, and then enter the chemical vapor deposition reaction unit through the porous screen. The fully vaporized catalyst particles react with the separately fed gaseous carbon source, and the cracked carbon source grows into high-purity single-walled carbon nanotubes on the surface of the fine catalyst. In the collection chamber at the end of the system, the single-walled carbon nanotubes are separated from the tail gas through the carbon nanotube collection membrane to obtain single-walled carbon nanotube products. In the present invention, the liquid catalyst is atomized in advance and then screened, which is easier to be fully vaporized to obtain small-sized catalyst particles with uniform particles, effectively inhibits the formation of large catalyst particles, effectively controls the growth diameter of single-walled carbon nanotubes, reduces the formation of amorphous carbon, and thus can improve the quality and purity of single-walled carbon nanotubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of an aerosol-assisted single-walled carbon nanotube preparation system of the present invention;

[0028] Figure 2Transmission electron microscope image of the single-walled carbon nanotubes prepared in Example 1;

[0029] Figure 3 Raman spectrum of the single-walled carbon nanotubes prepared in Example 1;

[0030] Figure 4 Transmission electron microscope image of the single-walled carbon nanotubes prepared in Comparative Example 2;

[0031] Reference numerals: 1 - liquid catalyst atomizing nozzle, 2 - carrier gas inlet, 3 - vacuum valve, 4 - porous screen, 5 - gaseous carbon source inlet, 6 - thermocouple, 7 - reaction chamber, 8 - collection chamber, 9 - carbon nanotube collection film, 10 - exhaust port. Detailed implementation manners

[0032] The features and technical effects of the present invention will be further described in detail below through specific examples, but the present invention is not limited thereby.

[0033] As Figure 1 shown, a system for aerosol-assisted preparation of single-walled carbon nanotubes according to the present invention includes a catalyst atomizing unit, a catalyst screening unit, a vapor-phase chemical deposition reaction unit and a collection unit with interconnected inner cavities; the catalyst screening unit is arranged at the connection between the catalyst atomizing unit and the vapor-phase chemical deposition reaction unit, and the collection unit is connected to the tail end of the vapor-phase chemical deposition reaction unit; the outer diameter of the catalyst screening unit is smaller than the outer diameters of the catalyst atomizing unit and the vapor-phase chemical deposition reaction unit.

[0034] Specifically, the catalyst atomizing unit and the vapor-phase chemical deposition reaction unit form a Venturi tube structure. The catalyst atomizing unit includes an atomizing chamber, which is composed of an integrally formed cylindrical inlet section and a tapered acceleration section. An atomizing nozzle and a carrier gas inlet are arranged in the middle of the inlet section of the atomizing chamber. The carrier gas inlet is located below the atomizing nozzle. A vacuum valve is arranged on the side wall of the inlet section of the atomizing chamber. The catalyst screening unit is arranged at the tail end of the tapered acceleration section. The vapor-phase chemical deposition reaction unit includes a reaction chamber. A gaseous carbon source inlet is arranged at the bottom of the side wall of the reaction chamber close to the catalyst screening unit; a thermocouple is arranged at the top of the reaction chamber.

[0035] In this embodiment, the atomizing nozzle is connected to the feeding device of the liquid catalyst, and the catalyst and catalyst additive mixed solution is atomized by using aerosol atomization technology. Specifically, when implemented, the atomized liquid and the carrier gas ejected from the atomizing nozzle enter the atomizing chamber with a larger space and enter the catalyst screening unit from the narrower inlet.

[0036] Specifically, the catalyst screening unit includes a porous sieve. Preferably, the porous sieve is a three-layer structure that fits tightly, and the pore size of the middle-layer porous sieve is smaller than that of the two outer-layer porous sieves. Here, the porous and high-temperature-resistant porous sieve blocks the larger catalyst droplets that have not been fully vaporized, and only allows the smaller and evenly distributed catalyst particles to continue to enter the chemical vapor deposition reaction unit. The large-sized droplets intercepted by the porous sieve contact the high-temperature porous sieve, quickly absorb heat and are vaporized again, and then enter the chemical vapor deposition reaction unit through the porous sieve. The fully vaporized catalyst particles react with the separately fed gaseous carbon source, and the cracked carbon source grows into high-purity single-walled carbon nanotubes on the surface of the fine catalyst. At the collection chamber at the end of the system, the single-walled carbon nanotubes are separated from the tail gas through the carbon nanotube collection membrane to obtain single-walled carbon nanotube products.

[0037] In the present invention, the catalyst is atomized by an atomizer to form a continuous, quantitative, and controllable addition based on carrier gases with different flow rates, which can effectively control the dosage and evaporation amount of the catalyst, avoid the collision and aggregation of particles to form large particles due to a large amount of evaporation, improve the catalyst activity and utilization rate, and significantly improve the product purity, up to 83%.

[0038] In some preferred embodiments, a temperature control accessory can be arranged on the periphery of the catalyst atomization unit. By controlling the temperature of the catalyst atomization unit to be constant, it is ensured that the catalyst solution and the catalyst assistant solution can always remain in a mist state and are sent into the chemical vapor deposition reaction chamber together with the carrier gas.

[0039] Specifically, the collection unit includes a collection chamber, an exhaust port is arranged on the collection chamber, and a carbon nanotube collection membrane is arranged inside the collection chamber.

[0040] In some preferred embodiments, a single-walled carbon nanotube collection structure is further arranged below the carbon nanotube collection membrane to collect the single-walled carbon nanotubes that fall from the carbon nanotube collection membrane. At a high-temperature environment of 1000 - 1500 °C, the carbon source is cracked, and the generated carbon atoms are adsorbed and nucleated on the surface of the catalyst, and finally grow into high-purity single-walled carbon nanotubes. The carbon nanotube collection membrane is realized by using a highly permeable membrane. The carrier gas carries the single-walled carbon nanotubes generated in the chemical vapor deposition reaction chamber and enters the collection chamber from the collection chamber inlet. When passing through the carbon nanotube collection membrane, the single-walled carbon nanotubes are filtered by the carbon nanotube collection membrane, and the tail gas is discharged from the exhaust port through the carbon nanotube collection membrane.

[0041] A method for aerosol-assisted preparation of single-walled carbon nanotubes is realized by using the above-mentioned aerosol-assisted preparation system for single-walled carbon nanotubes. The specific steps include:

[0042] S1: First, connect a vacuum machine through a vacuum valve, evacuate the inside of the system, close the vacuum valve, and then introduce a carrier gas through the carrier gas inlet to remove air;

[0043] S2: Atomize the liquid catalyst through an atomizing nozzle, and carry the atomized catalyst into the catalyst screening unit through a carrier gas. The unatomized liquid droplets here will be intercepted by a porous sieve and vaporized again. The fully vaporized catalyst enters the high-temperature chemical vapor deposition reaction unit. At the same time, the gaseous carbon source is injected into the chemical vapor deposition reaction unit through the gaseous carbon source inlet, and then cracks under the action of the catalyst to produce single-walled carbon nanotubes;

[0044] S3: In the collection unit, intercept and separate the generated single-walled carbon nanotubes from the tail gas through a carbon nanotube collection membrane, and collect them as a solid product.

[0045] In this embodiment, the carrier gas is one of argon, nitrogen or carbon dioxide. Preferably, the carrier gas is argon, and its flow rate is 10 - 40 L / min. At the same time, the flow rate of the carbon source gas is controlled at 0 - 20 L / min.

[0046] In this embodiment, the reaction temperature in the chemical vapor deposition reaction unit is 1000 - 1500 °C. Preferably, the reaction temperature is 1280 °C.

[0047] In practical applications, common carbon sources, catalysts, and catalyst assistants for preparing single-walled carbon nanotubes can all generate single-walled carbon nanotubes based on the system and method of the present invention. In this embodiment, the liquid catalyst is a mixed solution of a pre-prepared catalyst and a catalyst assistant. The catalyst is one or several of ferrocene, iron nitrate, iron carbonyl, cobaltocene, cobalt nitrate, nickelocene, nickel nitrate; the catalyst assistant is one or several of sulfur, thiophene, methanethiol, carbon disulfide; the mass ratio of the catalyst to the catalyst assistant is 50 - 100:1. Preferably, the mass ratio of the catalyst to the catalyst assistant is 100:1; the carbon source is one or several of methane, methanol, ethane, ethanol, propane, propylene.

[0048] Preferably, in this embodiment, the catalyst is ferrocene dissolved in methanol. Methanol as the catalyst solvent is also the carbon source for the reaction. The co-catalyst used is thiophene, and its mass ratio to ferrocene is 100:1.

[0049] Example 1

[0050] After evacuating the air inside the system of the present invention and introducing 10 L / min of argon, then turn on the power of the reaction furnace body below the chemical vapor deposition reaction unit to heat up to 1280 °C and keep the temperature constant.

[0051] During the temperature rise of the electric heating furnace, a ferrocene active component solution with a concentration of 1 wt% is prepared. Methanol is used as the solvent and also serves as the carbon source for this reaction. Thiophene, with a concentration of 0.01 wt%, is added as a catalyst promoter. After stirring and mixing evenly, a liquid catalyst is obtained. The liquid catalyst is transferred to the atomizer feed tank, and the speed of the atomizer argon carrier gas is set at 3 L / min. After the temperature stabilizes at 1280 °C for five minutes, the atomizer switch is turned on, and the atomized catalyst droplets are carried into the catalyst screening unit by the carrier gas. The unatomized droplets are intercepted by the porous screen structure and re-vaporized. The fully vaporized catalyst enters the high-temperature chemical vapor deposition reaction unit to generate single-walled carbon nanotubes.

[0052] The sample is analyzed by transmission electron microscopy, and the analysis results are as Figure 2 shown in and Table 1. The product is single-walled carbon nanotubes with an average diameter of 2.1 nanometers. Further Raman spectroscopy analysis of this product is as Figure 3 shown. The G / D peak ratio reaches 16, indicating that it is a single-walled carbon nanotube product with good quality.

[0053] Example 2

[0054] After evacuating the air inside the system of the present invention, nitrogen is introduced at 10 L / min. Then, the power supply of the reaction furnace body below the chemical vapor deposition reaction unit is turned on to heat up to 1200 °C and keep the temperature constant.

[0055] A mixed solution of ferric nitrate with a concentration of 0.5 wt% and cobalt ferric nitrate with a concentration of 0.5 wt% as the active component is prepared. Ethanol is used as the solvent, and thiophene, with a concentration of 0.01 wt%, is added as a catalyst promoter. After stirring evenly, a liquid catalyst is obtained. The liquid catalyst is transferred to the atomizer feed tank, and the speed of the atomizer nitrogen carrier gas is set at 5 L / min. After the temperature stabilizes at 1200 °C for five minutes, the atomizer switch is turned on, and the atomized catalyst droplets are carried into the catalyst screening unit by the carrier gas; at the same time, the feed switch of the methane carbon source is turned on, and 1 L / min of methane gas is added; the fully vaporized catalyst enters the 1200 °C high-temperature chemical vapor deposition reaction unit and reacts with methane and ethanol to generate single-walled carbon nanotubes, and the generated carbon nanotube sample is collected in the collection chamber.

[0056] The sample is analyzed by transmission electron microscopy, and the analysis results are shown in Table 1. The product is mainly single-walled carbon nanotubes with a diameter of 2.3 nanometers.

[0057] Comparative Example 1

[0058] A commonly used horizontal tube furnace is selected as the reaction system. After evacuating the air inside the reaction furnace, 10 L / min of argon is introduced. Then, the power supply of the reaction furnace body is turned on to heat up to 1280 °C and keep the temperature constant.

[0059] During the heating period of the electric heating furnace, a ferrocene active component solution with a concentration of 1wt% is prepared, methanol is used as a solvent and also as a carbon source for the reaction, and a catalyst auxiliary thiophene is added with a concentration of 0.01wt%, and stirred and mixed evenly to obtain a catalyst mixture; the above catalyst mixture is not atomized, but directly injected into the reaction furnace through an injection pump, and the injection speed is 4mL / min. Since no atomization is performed, the catalyst solution directly enters the reaction zone in the form of larger droplets; at the same time, since no screening treatment is performed, the catalyst particles are not evenly distributed, resulting in uneven particle size and some particles are too large; thereafter, the generated product is collected in a collection chamber.

[0060] Electron microscope analysis revealed that there were a large number of unreacted catalyst particles and amorphous carbon impurities in the carbon nanotube product, and the carbon nanotube diameter distribution was uneven, ranging from 2 to 7 nanometers, and the purity of single-walled carbon nanotubes was low. This is because under high temperature conditions, the catalyst particles agglomerated and could not effectively catalyze the cracking of the carbon source, generating a large number of amorphous carbon impurities and reducing the content of single-walled carbon nanotubes. The Raman tube spectrum G / D ratio of the sample was 10, which also showed that the quality of the carbon nanotubes was average.

[0061] Comparative Example 2

[0062] The catalyst screening unit in the system of the present invention is removed, and after being refitted and connected, a vacuum is drawn, and then 10 L / min of argon is introduced, and then the power supply of the reaction furnace is turned on to heat the temperature to 1280° C. and keep the temperature constant.

[0063] During the heating period of the electric heating furnace, a ferrocene active component solution with a concentration of 1wt% is prepared, methanol is used as a solvent and also as a carbon source for the reaction, and a catalyst promoter thiophene is added with a concentration of 0.01wt%, and stirred and mixed evenly to obtain a liquid catalyst. The liquid catalyst is transferred to the atomizer feed tank, and the speed of the atomizer argon carrier gas is set to 3 L / min; when the temperature is stable at 1280℃ for five minutes, the atomizer switch is turned on, and the atomized catalyst is directly brought into the high-temperature gas phase chemical deposition reaction unit through the carrier gas without being screened by the catalyst screening unit, and the generated single-walled carbon nanotubes are collected at the end of the system.

[0064] The sample was analyzed by transmission electron microscopy, and the results were as follows: Figure 4 As shown, the product is mainly single-walled carbon nanotubes with an average diameter of 2.4 nanometers and contains a large number of amorphous carbon spheres. Further Raman spectroscopy analysis of the product shows that its G / D peak ratio reaches 11, indicating that the quality of carbon nanotubes will be reduced without catalyst screening treatment.

[0065] Table 1 Sample analysis results of Examples 1-2 and Comparative Examples 1-2

[0066]

[0067] By comparing Example 1 with Example 2 to study the influence of the type and concentration of the catalyst active component on the single-walled carbon nanotube product, it can be seen that when ferrocene with a concentration of 1 wt% is used as the catalyst active component in Example 1, the average diameter of the single-walled carbon nanotubes is 2.1 nm; while when iron nitrate with a concentration of 0.5 wt% is used as the catalyst active component in Example 2, the diameter of the single-walled carbon nanotubes is 2.3 nm. This indicates that when ferrocene is used as the catalyst active component, the product has a higher yield, smaller carbon nanotube diameter, and better electrical properties.

[0068] By comparing Example 1 with Comparative Example 1 to study the influence of atomization and screening treatments on the single-walled carbon nanotube product, it can be seen that after the atomization and screening treatments in Example 1, the catalyst droplets are evenly dispersed, and the final yield of the single-walled carbon nanotubes can reach 10 times, with an average diameter of 2.1 nm; while in Comparative Example 1, without the atomization and screening treatments, the morphology of the catalyst particles is poor, and the finally obtained content of the single-walled carbon nanotubes is extremely low, the yield is less than expected, and the diameter distribution of the carbon nanotubes is uneven, ranging from 2 to 7 nm. This shows that the atomization and screening treatments are crucial for the uniform dispersion of the catalyst particles, directly affecting the yield, purity, and electrical properties of the single-walled carbon nanotubes.

[0069] By comparing Example 1 with Comparative Example 2 to study the influence of the catalyst screening treatment on the single-walled carbon nanotube product, it can be seen that after the further screening treatment of the atomized catalyst in Example 1, the catalyst vapor is uniform, and the unvaporized catalyst is intercepted by the catalyst screening unit, while the catalyst vapor without the catalyst screening unit contains unvaporized droplets, reducing the uniformity of the catalyst and thus reducing the quality of the single-walled carbon nanotubes.

[0070] After using the technical solution of the present invention, when preparing single-walled carbon nanotubes by the aerosol-assisted technique, a system composed of a catalyst atomization unit, a catalyst screening unit, a vapor-phase chemical deposition reaction unit, and a collection unit is utilized. In particular, the combined action of the atomization and screening units realizes the uniform and fine dispersion of the catalyst, which can significantly improve the quality of the single-walled carbon nanotube product. This method effectively avoids the disadvantages of uneven distribution of catalyst particles, excessive amorphous carbon impurities in the product, and low reaction efficiency of the carbon source in the traditional preparation method, and can finely control the particle size and distribution of the catalyst, ensuring that the produced single-walled carbon nanotubes have higher purity and consistency. By comprehensively comparing the product properties in the table, it shows that this method can effectively improve the quality of single-walled carbon nanotubes, promote their efficient and stable production, and has broad application prospects.

Claims

1. An aerosol-assisted single-walled carbon nanotube preparation system, characterized in that: It includes a catalyst atomization unit, a catalyst screening unit, a chemical vapor deposition reaction unit, and a collection unit with interconnected inner cavities; The catalyst screening unit is arranged at the connection between the catalyst atomization unit and the chemical vapor deposition reaction unit, and the collection unit is connected to the tail end of the chemical vapor deposition reaction unit; The outer diameter of the catalyst screening unit is smaller than the outer diameters of the catalyst atomization unit and the chemical vapor deposition reaction unit; The catalyst atomization unit and the chemical vapor deposition reaction unit form a Venturi tube structure. The catalyst atomization unit includes an atomization chamber, which is composed of an integrally formed cylindrical inlet section and a tapered acceleration section. An atomizing nozzle and a carrier gas inlet are arranged in the middle of the inlet section of the atomization chamber. The carrier gas inlet is located below the atomizing nozzle. A vacuum valve is arranged on the side wall of the inlet section of the atomization chamber. The catalyst screening unit is arranged at the tail end of the tapered acceleration section. The chemical vapor deposition reaction unit includes a reaction chamber. A gaseous carbon source inlet is arranged at the bottom of the side wall of the reaction chamber close to the catalyst screening unit; A thermocouple is arranged at the top of the reaction chamber; The collection unit includes a collection chamber, an exhaust port is arranged on the collection chamber, and a carbon nanotube collection film is arranged in the collection chamber; The catalyst screening unit includes a porous screen, and the porous screen is a three-layer structure that fits tightly. The pore diameter of the middle-layer porous screen is smaller than the pore diameters of the two outer-layer porous screens.

2. A method for aerosol-assisted preparation of single-walled carbon nanotubes is realized by using the aerosol-assisted single-walled carbon nanotube preparation system described in claim 1, characterized in that, The specific steps include: S1: First, connect a vacuum machine through the vacuum valve to evacuate the inside of the system, close the vacuum valve, and then introduce a carrier gas through the carrier gas inlet to expel air; S2: Atomize the liquid catalyst through the atomizing nozzle, and bring the atomized catalyst into the catalyst screening unit through the carrier gas. The unatomized liquid droplets here will be intercepted by the porous screen and vaporized again. The fully vaporized catalyst enters the high-temperature chemical vapor deposition reaction unit. At the same time, the gaseous carbon source is sprayed into the chemical vapor deposition reaction unit through the gaseous carbon source inlet, and then single-walled carbon nanotubes are produced by cracking under the action of the catalyst; S3: In the collection unit, the generated single-walled carbon nanotubes are intercepted and separated from the tail gas through the carbon nanotube collection film and collected as a solid product.

3. The method for preparing single-walled carbon nanotubes by aerosol assistance according to claim 2, wherein: The carrier gas is one of argon, nitrogen, and carbon dioxide. The flow rate of the carrier gas is controlled at 10 - 40 L / min, and the flow rate of the carbon source gas is controlled at 0 - 20 L / min.

4. The method for preparing single-walled carbon nanotubes by aerosol assistance according to claim 3, wherein: The liquid catalyst is a mixed solution of a pre-prepared catalyst and a catalyst assistant. The catalyst is one or several of ferrocene, iron nitrate, iron carbonyl, cobaltocene, cobalt nitrate, nickelocene, nickel nitrate; The catalyst assistant is one or several of sulfur, thiophene, methanethiol, carbon disulfide. The solvent used in the mixed solution is one of methanol and ethanol. The mass ratio of the solvent to the catalyst is 100:

1. The mass ratio of the catalyst to the catalyst assistant is 50 - 100:

1. The reaction temperature in the chemical vapor deposition reaction unit is 1000 - 1500 °C.

5. A method for aerosol-assisted preparation of single-walled carbon nanotubes according to claim 4, characterized in that: The mass ratio of the catalyst to the catalyst assistant is 100:1; The reaction temperature in the chemical vapor deposition reaction unit is 1280 °C.

6. A method for preparing single-walled carbon nanotubes assisted by aerosol according to claim 5, characterized in that: The carbon source is one or several of methane, methanol, ethane, ethanol, propane, and propylene.

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