Apparatus and method for improving yield of single-walled carbon nanotubes produced by floating catalytic method

Abstract

The application discloses a device for improving the yield of single-walled carbon nanotubes prepared by a floating catalytic method, and relates to the field of single-walled carbon nanotube preparation. The device comprises a two-section heating device, a gas-liquid supply device and a product collecting device. The gas-liquid supply device is sealingly connected to the lower end inlet of the two-section heating device, and a cooling pipeline is communicated with the upper end outlet of the two-section heating device. The end of the cooling pipeline, which is far away from the two-section heating device, is connected with the product collecting device. The lower end furnace body and the cylindrical intermediate furnace body of the two-section heating device are filled with high-temperature-resistant ceramic microspheres. The application makes an innovative breakthrough on the basis of the original floating catalytic cracking method. By adding the high-temperature-resistant ceramic microspheres, the defects of the traditional floating catalytic cracking method, which simply realizes high yield by enlarging the size of the cavity, are changed in principle. Meanwhile, two key factors, i.e., the distribution of the carrier gas flow and the temperature distribution of the cavity section when the carrier gas passes through, are solved. Therefore, the yield of the single-walled carbon nanotubes prepared by the floating catalytic cracking method is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of single-walled carbon nanotube preparation, specifically to an apparatus and method for improving the yield of single-walled carbon nanotubes prepared by a floating catalytic method. Background Technology

[0002] Single-walled carbon nanotubes (SWCNTs), as a novel nanomaterial, are widely used in new energy, transparent displays, antistatic agents, semiconductors, and engineering plastics due to their excellent electrical conductivity, thermal conductivity, temperature resistance, chemical resistance, and mechanical properties. However, the mass production technology of SWCNTs has always restricted their application in various fields. Therefore, how to achieve low-cost, large-scale production is an urgent problem to be solved.

[0003] Currently, there are three main methods for preparing single-walled carbon nanotubes: electric arc method, laser ablation method, and chemical vapor deposition method. Existing electric arc and laser ablation methods suffer from low yields and high energy consumption, making large-scale production difficult. Floating catalytic chemical vapor deposition, due to its continuous raw material supply and product collection, is currently the most feasible technology for mass production.

[0004] However, in existing technologies, the yield has remained low (below 1 gram per hour) due to the limitations of the synthesis equipment's chamber size. Increasing the number of reaction channels can further improve the production capacity, but excessive channels lead to complex equipment structures, making it difficult to control product consistency and hindering mass production. Increasing the chamber size is another way to increase production capacity, but because the reaction conditions for single-walled carbon nanotubes are harsh, enlarging the chamber size alters the temperature field distribution within the furnace. The airflow forms vortices within the chamber, and the carrier gas has a low heat capacity. Introducing cold air causes uneven temperature distribution in the middle and at the tube walls, making it easier for carbon nanotubes to grow along the tube walls, thus failing to achieve volumetric growth and resulting in low yield and purity.

[0005] For the preparation of single-walled carbon nanotubes using the existing floating catalytic pyrolysis method, how to optimize the reaction chamber structure from the perspective of the growth mechanism of single-walled carbon nanotubes, fully realize the dynamic process of gasification-pyrolysis-carbon melting-precipitation of organic precursors, and thus improve the yield of single-walled carbon nanotubes, is an urgent problem to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide an apparatus and method for improving the yield of single-walled carbon nanotubes prepared by floating catalysis.

[0007] The present invention can be achieved by the following technical solution: an apparatus for improving the yield of single-walled carbon nanotubes prepared by floating catalysis, comprising a two-stage heating device, a gas-liquid supply device and a product collection device, wherein the lower inlet of the two-stage heating device is sealed and connected to the gas-liquid supply device, and the upper outlet is connected to a cooling pipe, wherein the end of the cooling pipe away from the two-stage heating device is connected to the product collection device.

[0008] A further technical improvement of the present invention is that: the two-stage heating device includes a conical upper furnace body, a lower furnace body, and a cylindrical middle furnace body, wherein the conical furnace bodies at both ends are made of stainless steel, and the cylindrical middle furnace body is made of corundum tube;

[0009] Furthermore, a resistance wire is installed in the lower part of the furnace body, and multiple silicon molybdenum rods for heating are installed at equal angles in the cylindrical middle furnace body.

[0010] A further technical improvement of the present invention is that: both ends of the tapered furnace body and the cylindrical middle furnace body are provided with a heat insulation layer, and a stainless steel cover is provided outside the heat insulation layer.

[0011] A further technical improvement of the present invention is that 40% to 60% of the volume of the lower furnace body and the cylindrical intermediate furnace body is filled with high-temperature resistant ceramic microspheres.

[0012] A further technical improvement of the present invention is that the high-temperature resistant ceramic microspheres are composed of one or more of silicon oxide, zirconium oxide, alumina and silicon carbide;

[0013] The diameter of the high-temperature resistant ceramic microspheres is 2 to 10 mm. The high-temperature resistant ceramic microspheres are filled in the two-stage heating device with one or more diameters or with a gradual change in diameter from bottom to top.

[0014] A further technical improvement of the present invention is that the cooling pipe is provided with a vertical telescopic mechanism for collecting products in the furnace and a gas purging device for blowing them into the product collection device.

[0015] A further technical improvement of the present invention is that the product collection device is set as a stainless steel tank, and a filter plate with a microporous structure is installed inside it.

[0016] The method for preparing wall carbon nanotubes using the above-described apparatus includes the following steps:

[0017] Step 1: Connect the gas-liquid pipeline and place the high-temperature resistant ceramic microspheres with the set particle size and quantity into the two-section furnace body;

[0018] Step 2: Inert gas is introduced to purge the air from the furnace body, and the temperatures of the two temperature zones are set according to the process requirements.

[0019] Step 3: Set the temperature and stabilize it for more than 2 hours until the temperature of the high-temperature resistant ceramic microspheres inside the furnace is uniform;

[0020] Step 4: Open the gas pipeline and organic liquid carbon source precursor of the gas-liquid supply device, and supply liquid at a certain gas flow rate and liquid supply rate to start the synthesis of single-walled carbon nanotubes.

[0021] Step 5: Open the vertical telescopic mechanism and gas purging device on the cooling pipe to collect the product into the cavity of the product collection device.

[0022] A further technical improvement of the present invention is that, in step two, the temperature of the lower furnace body is set to 300-500°C, and the temperature of the cylindrical middle furnace body is set to 1100-1600°C.

[0023] A further technical improvement of the present invention is that, in step four, the gas flow rate is set to 5 L / min to 100 L / min; and the liquid flow rate is set to 0.5 ml / min to 20 ml / min.

[0024] It should be noted that the gas flow in step four is one or a mixture of nitrogen, argon, and helium, with argon being preferred.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. In this invention, high-temperature resistant ceramic microspheres are filled in a low-temperature conical vaporization region. The capillary action between the microspheres can be used to rapidly diffuse the liquid carbon source, which can disperse the blown-in gas flow disorderly and form a stable turbulent flow. At the same time, the gas flow moves towards the high-temperature region. This is different from the floating catalysis method in the prior art. This method has obvious advantages in terms of process control, stability, and consistency. The cavity space is utilized more fully and it is easier to achieve volume growth.

[0027] 2. In this invention, high-temperature resistant ceramic microspheres fill 40%–60% of the high-temperature region, allowing for more thorough contact between the catalyst particles and the carbon source after pyrolysis, facilitating the carbon melting process and solving the problem of carbon source waste caused by insufficient contact between the carbon source and catalyst in traditional floating catalytic pyrolysis methods. Simultaneously, because the high-temperature resistant ceramic microspheres have a higher specific heat capacity than gas, the instantaneous temperature change when the gas flows through the microspheres is smaller, which is more conducive to the volume growth of single-walled carbon nanotubes, enabling mass production. Attached Figure Description

[0028] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0029] Figure 1 This is a schematic diagram of the overall device structure of the present invention;

[0030] Figure 2 This is a schematic flowchart of the preparation method of the present invention;

[0031] Figure 3 This is a TEM image of carbon nanotubes in Example 6 of the present invention;

[0032] Figure 4 This is a SEM image of carbon nanotubes from Example 6 of the present invention.

[0033] In the diagram: 1. Gas-liquid supply device; 2. Two-stage heating device; 3. High-temperature resistant ceramic microspheres; 4. Cooling pipe; 5. Product collection device; 11. Capillary liquid pipe; 12. Gas pipe; 13. Sealing flange; 21. Resistance wire; 22. Silicon molybdenum rod; 23. Corundum tube furnace body; 24. Upper furnace body; 41. Gas purging device; 42. Vertical telescopic mechanism; 51. Filter plate; 52. Product outlet; 53. Waste gas outlet. Detailed Implementation

[0034] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0035] Please see Figure 1-4 As shown, an apparatus for improving the yield of single-walled carbon nanotubes prepared by floating catalysis includes a two-stage heating device 2, a gas-liquid supply device 1, and a product collection device 5. The gas-liquid supply device 1 is located at the bottom of the two-stage heating device 2. A cooling pipe 4 is provided between the two-stage heating device 2 and the product collection device 5. The two ends of the cooling pipe 4 are respectively connected to the top of the two-stage heating device 2 and the top of the product collection device 5.

[0036] Specifically, the gas-liquid supply device 1 includes a capillary liquid pipe 11 and a gas pipe 12. The capillary liquid pipe 11 and the gas pipe 12 are coaxially arranged, and the gas pipe 12 is located outside the capillary liquid pipe 11. The top ends of both are sealed at the bottom of the two-stage heating device 2 by a sealing flange 13. The capillary liquid pipe 11 of the gas-liquid supply device 1 is externally connected to a flow meter and a liquid supply pump.

[0037] More specifically, the inner diameter of the capillary liquid conduit 11 is 0.3 to 1.5 mm, and its material is stainless steel; both ends of the capillary liquid conduit extend out of the gas conduit 12, with the extension distance set to 5 to 20 mm.

[0038] Specifically, the two-section heating device 2 includes a cylindrical middle section and upper and lower conical converging structural sections. The middle section is set as a corundum tube furnace body 23, the upper conical converging structural section is set as a stainless steel furnace body, marked as upper furnace body 24, and the lower conical converging structural section is also set as a stainless steel furnace body, marked as lower furnace body 25. A resistance wire 21 is set inside the lower furnace body 25, and silicon molybdenum rods 22 are uniformly arranged at equal angles on the inner wall of the corundum tube furnace body 23 for heating.

[0039] Furthermore, the upper and lower ends of the furnace body and the outer layer of the corundum tube furnace body 23 are all equipped with a heat insulation layer, and a stainless steel cover is installed outside the heat insulation layer to ensure the airtightness of the furnace chamber.

[0040] More specifically, the conical cavity of the lower furnace body 25 has a narrow opening diameter of 50-150mm and a wide opening diameter of 100-500mm. The height of the conical stainless steel furnace body is 300-500mm. The lower furnace body 25 is heated by resistance wire 21 at a heating temperature of 300-500℃.

[0041] The corundum tube furnace body 23 is heated by silicon molybdenum rods 22. The diameter of the furnace tube is 100-500 mm, the height of the furnace body is 600-1000 mm, the length of the silicon molybdenum rod heating zone is 200-400 mm, and the heating temperature is 1100-1600℃.

[0042] The two-stage heating device 2 is filled with high-temperature resistant ceramic microspheres 3. The high-temperature resistant ceramic microspheres 3 fill the cavity of the lower furnace body 25 and fill the corundum tube furnace body 23 by 40% to 60%.

[0043] The high-temperature resistant ceramic microspheres 3 are one or more of the following: silicon dioxide, zirconium oxide, alumina, silicon carbide, etc.

[0044] More often, the diameter of the high-temperature resistant ceramic microspheres 3 is 0.5-20 mm, preferably 2-10 mm; the high-temperature resistant ceramic microspheres 3 can be of uniform diameter or a mixture of different diameters, or the diameter can be gradually varied from bottom to top; in order to enable the gas-liquid mixture to rapidly vaporize and diffuse evenly in the high-temperature resistant ceramic microspheres 3, it is preferred that the lower end has a small diameter of 2-5 mm and gradually transitions to the upper end with a large diameter of 5-10 mm.

[0045] Specifically, the cooling pipe 4 is made of stainless steel. A vertical telescopic mechanism 42 is installed on the cooling pipe 4 at the opening position directly above the two-section heating device 2, and a gas purging device 41 is horizontally installed on one side of the cooling pipe 4.

[0046] More specifically, the vertical telescopic mechanism 42 is used to collect the products accumulated in the furnace to the inlet of the cooling pipe 4, and the gas purging device 41 blows inert gas during operation and blows the products on the vertical telescopic mechanism 42 into the cooling pipe 4.

[0047] Specifically, the product collection device 5 is a stainless steel tank with its upper inlet located at one end of the cooling pipe 4 and its lower exhaust outlet 53 connected to the exhaust gas treatment system. A filter plate 51 is horizontally installed inside the product collection device 5, and a product outlet 52 is provided on the filter plate 51.

[0048] The filter plate 51 is specifically provided with a microporous structure, and can be a metal plate such as titanium plate or copper plate, or a ceramic sand core filter plate.

[0049] The above-mentioned apparatus was used to prepare single-walled carbon nanotubes. The size and structure of the apparatus were set as follows: the diameter of the narrow end of the conical cavity at both ends was 150 mm, the diameter of the wide end was 500 mm, the diameter of the corundum tube furnace body 23 was 500 mm, and the height of the furnace body was 1 m; the organic precursor formula (mass ratio) was: ethanol / benzene / ferrocene / thiophene = 85 / 15 / 5 / 2.

[0050] The following are several examples and comparative examples of using this device to prepare single-walled carbon nanotubes:

[0051] Example 1

[0052] Step 1: Connect the gas-liquid pipeline, add 2mm high-temperature resistant ceramic microspheres 3 into the lower conical furnace body 25, and add 50% volume of 10mm high-temperature resistant ceramic microspheres 3 into the corundum tube furnace body 23.

[0053] Step 2: Introduce argon gas to purge the air inside the cavity, and set the temperature of the lower furnace body 25 to 400℃ and the temperature of the high-temperature zone of the corundum tube furnace body 23 to 1550℃.

[0054] Step 3: Set the temperature to reach and stabilize for more than 2 hours, until the temperature of the high-temperature resistant ceramic microspheres 3 inside the furnace is uniform;

[0055] Step 4: Turn on the argon gas and organic liquid carbon source precursor, and supply the liquid at a certain gas flow rate of 50 L / min and a liquid supply rate of 10 mL / min to start the synthesis of single-walled carbon nanotubes;

[0056] Step 5: Open the vertical telescopic mechanism 42 and the gas purging device 41 on the cooling pipe 4 to collect the product into the cavity of the product collection device 5;

[0057] In this first example, the yield of the prepared single-walled carbon nanotube powder was 52 g / h, the purity was 76%, and the G / D ratio was 71.

[0058] Example 2

[0059] Step 1: Connect the gas-liquid pipelines and add 10mm high-temperature resistant ceramic microspheres 3 into both the lower conical furnace body 25 and the 50% volume corundum tube furnace body 23.

[0060] Step 2: Introduce argon gas to purge the air inside the cavity, and set the temperature of the lower furnace body 25 to 400℃ and the temperature of the high-temperature zone of the corundum tube furnace body 23 to 1550℃.

[0061] Step 3: Set the temperature to reach and stabilize for more than 2 hours, until the temperature of the high-temperature resistant ceramic microspheres 3 inside the furnace is uniform;

[0062] Step 4: Turn on the argon gas and organic liquid carbon source precursor, and supply the liquid at a certain gas flow rate of 50 L / min and a liquid supply rate of 10 mL / min to start the synthesis of single-walled carbon nanotubes;

[0063] Step 5: Open the vertical telescopic mechanism 42 and the gas purging device 41 on the cooling pipe 4 to collect the product into the cavity of the product collection device 5;

[0064] The single-walled carbon nanotube powder prepared in Example 2 had a yield of 38 g / h, a purity of 67%, and a G / D ratio of 65.

[0065] Example 3

[0066] Step 1: Connect the gas-liquid pipeline, add 5mm high-temperature resistant ceramic microspheres 3 into the lower furnace body 25, and add 50% volume of 20mm high-temperature resistant ceramic microspheres 3 into the corundum tube furnace body 23;

[0067] Step 2: Turn on the argon gas and organic liquid carbon source precursor, and set the temperature of the lower furnace body 25 to 400℃ and the temperature of the high-temperature zone of the corundum tube to 1550℃;

[0068] Step 3: Set the temperature to reach and stabilize for more than 2 hours, until the temperature of the high-temperature resistant ceramic microspheres 3 inside the furnace is uniform;

[0069] Step 4: Turn on the argon gas and organic liquid carbon source precursor, and supply the liquid at a certain gas flow rate of 50 L / min and a liquid supply rate of 10 mL / min to start the synthesis of single-walled carbon nanotubes;

[0070] Step 5: Open the vertical telescopic mechanism 42 and the gas purging device 41 on the cooling pipe 4 to collect the product into the cavity of the product collection device 5;

[0071] The single-walled carbon nanotube powder prepared in Example 3 had a yield of 27 g / h, a purity of 69%, and a G / D ratio of 59.

[0072] Example 4

[0073] Step 1: Connect the gas-liquid pipeline, add 2mm high-temperature resistant ceramic microspheres 3 into the lower furnace body 25, and add 60% volume of 10mm high-temperature resistant ceramic microspheres 3 into the corundum tube furnace body 23;

[0074] Step 2: Introduce argon gas to purge the air inside the cavity, and set the temperature of the lower furnace body 25 to 400℃ and the temperature of the high-temperature zone of the corundum tube furnace body 23 to 1550℃.

[0075] Step 3: Set the temperature to reach and stabilize for more than 2 hours, until the temperature of the high-temperature resistant ceramic microspheres 3 inside the furnace is uniform;

[0076] Step 4: Turn on the argon gas and organic liquid carbon source precursor, and supply the liquid at a certain gas flow rate of 50 L / min and a liquid supply rate of 10 mL / min to start the synthesis of single-walled carbon nanotubes;

[0077] Step 5: Open the vertical telescopic mechanism 42 and the gas purging device 41 on the cooling pipe 4 to collect the product into the cavity of the product collection device 5;

[0078] The single-walled carbon nanotube powder prepared in Example 4 had a yield of 49 g / h, a purity of 75%, and a G / D ratio of 72.

[0079] Example 5

[0080] Step 1: Connect the gas-liquid pipeline, add 2mm high-temperature resistant ceramic microspheres 3 into the lower furnace body 25, and add 40% volume of 10mm high-temperature resistant ceramic microspheres 3 into the corundum tube furnace body 23;

[0081] Step 2: Introduce argon gas to purge the air inside the cavity, and set the temperature of the lower furnace body 25 to 400℃ and the temperature of the high-temperature zone of the corundum tube furnace body 23 to 1550℃.

[0082] Step 3: Set the temperature to reach and stabilize for more than 2 hours, until the temperature of the high-temperature resistant ceramic microspheres 3 inside the furnace is uniform;

[0083] Step 4: Turn on the argon gas and organic liquid carbon source precursor, and supply the liquid at a certain gas flow rate of 50 L / min and a liquid supply rate of 10 mL / min to start the synthesis of single-walled carbon nanotubes;

[0084] Step 5: Open the vertical telescopic mechanism 42 and the gas purging device 41 on the cooling pipe 4 to collect the product into the cavity of the product collection device 5;

[0085] The single-walled carbon nanotube powder prepared in Example 5 had a yield of 45 g / h, a purity of 71%, and a G / D ratio of 65.

[0086] Example 6

[0087] Step 1: Connect the gas-liquid pipelines and add 2mm high-temperature resistant ceramic microspheres 3 into both the lower conical furnace body 25 and the 50% volume corundum tube furnace body 23.

[0088] Step 2: Introduce argon gas to purge the air inside the cavity, and set the temperature of the lower furnace body 25 to 400℃ and the temperature of the high-temperature zone of the corundum tube furnace body 23 to 1550℃.

[0089] Step 3: Set the temperature to reach and stabilize for more than 2 hours, until the temperature of the high-temperature resistant ceramic microspheres 3 inside the furnace is uniform;

[0090] Step 4: Turn on the argon gas and organic liquid carbon source precursor, and supply the liquid at a certain gas flow rate of 50 L / min and a liquid supply rate of 10 mL / min to start the synthesis of single-walled carbon nanotubes;

[0091] Step 5: Open the vertical telescopic mechanism 42 and the gas purging device 41 on the cooling pipe 4 to collect the product into the cavity of the product collection device 5;

[0092] The single-walled carbon nanotube powder prepared in Example 6 had a yield of 55 g / h, a purity of 69%, and a G / D ratio of 68; Figure 3 It can be seen that the single-walled carbon nanotubes in the product are formed by 1 to 7 single-walled carbon nanotubes forming a tubular network structure with a length of several micrometers. The catalyst particles are partially aggregated and randomly distributed between the single-walled carbon nanotube network. Figure 4 The SEM images show that the single-walled carbon nanotube bundles are randomly arranged and have a length greater than 5 μm.

[0093] Example 7

[0094] Step 1: Connect the gas-liquid pipelines and add 20mm high-temperature resistant ceramic microspheres 3 into both the lower conical furnace body 25 and the 50% volume corundum tube furnace body 23.

[0095] Step 2: Introduce argon gas to purge the air inside the cavity, and set the temperature of the lower furnace body 25 to 400℃ and the temperature of the high-temperature zone of the corundum tube furnace body 23 to 1550℃.

[0096] Step 3: Set the temperature to reach and stabilize for more than 2 hours, until the temperature of the high-temperature resistant ceramic microspheres 3 inside the furnace is uniform;

[0097] Step 4: Turn on the argon gas and organic liquid carbon source precursor, and supply the liquid at a certain gas flow rate of 50 L / min and a liquid supply rate of 10 mL / min to start the synthesis of single-walled carbon nanotubes;

[0098] Step 5: Open the vertical telescopic mechanism 42 and the gas purging device 41 on the cooling pipe 4 to collect the product into the cavity of the product collection device 5;

[0099] The single-walled carbon nanotube powder prepared in Example 7 had a yield of 25 g / h, a purity of 66%, and a G / D ratio of 69.

[0100] Comparative Example 1

[0101] Comparative Example 1 follows the same steps as Example 7, except that the diameter of the high-temperature resistant ceramic microspheres 3 is changed to 50 mm.

[0102] The yield of the single-walled carbon nanotube powder prepared in this comparative example was 8 g / h, the purity was 45%, and the G / D ratio was 32.

[0103] Comparative Example 2

[0104] Comparative Example 2 follows the same steps as Example 7, except that the diameter of the high-temperature resistant ceramic microspheres 3 is 0.5 mm different.

[0105] In this comparative example, the airflow pressure was too high, preventing the airflow from passing smoothly and resulting in no product.

[0106] Comparative Example 3

[0107] Comparative Example 3 follows the same steps as Example 7, except that it does not use high-temperature resistant ceramic microspheres 3;

[0108] The yield of the single-walled carbon nanotube powder prepared in this comparative example was 3 g / h, the purity was 42%, and the G / D ratio was 34.

[0109] As demonstrated by the above embodiments and comparative examples, by filling the lower furnace body 25 with high-temperature resistant ceramic microspheres 3, the liquid carbon source can be rapidly diffused by utilizing the capillary action between the gaps in the high-temperature resistant ceramic microspheres 3. This can disrupt the disordered airflow, forming a stable turbulent flow, which then moves upwards to the high-temperature zone. The high-temperature zone is filled with 40% to 60% of its volume of high-temperature resistant ceramic microspheres 3, and the diameter of the high-temperature resistant ceramic microspheres 3 in the high-temperature zone is larger than that in the lower furnace body 25. This method is more conducive to the volume growth of single-walled carbon nanotubes and enables mass production. The yield of single-walled carbon nanotubes prepared by this method is 5 g / h to 70 g / h, the purity of TGA analysis is 65% to 78%, and the Raman G / D ratio is 46 to 77.

[0110] It should be noted that organic liquid precursors are existing formulations used to synthesize single-walled carbon nanotubes, and generally include carbon sources, catalysts, promoters, etchants, etc.

[0111] The carbon sources include ethanol, methanol, toluene, xylene, tetrahydrofuran, benzene, n-hexane, cyclohexane, etc.

[0112] Catalysts are generally ferrocene, nickel succinate, cobalt succinate, ferric chloride, iron carbonyl, iron lactate, etc.

[0113] Accelerators are generally sulfur-containing compounds.

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An apparatus for increasing the yield of single-walled carbon nanotubes produced by a floating catalytic method, characterized by: It comprises two-stage heating device (2), gas-liquid supply device (1) and product collection device (5), the lower end of the two-stage heating device (2) is sealingly connected with the gas-liquid supply device (1), the upper end is communicated with the cooling pipeline (4), and the end of the cooling pipeline (4) away from the two-stage heating device (2) is connected with the product collection device (5); The two-stage heating device (2) comprises a conical converging upper furnace body (24) and a lower furnace body (25) and a cylindrical intermediate furnace body, the two end conical converging furnace bodies are made of stainless steel, and the cylindrical intermediate furnace body is made of corundum pipe; The lower furnace body (25) is provided with resistance wires (21), and the cylindrical intermediate furnace body is provided with a plurality of silicon-molybdenum rods (22) at equal angles. The lower furnace body (25) and the cylindrical intermediate furnace body are filled with high-temperature-resistant ceramic microspheres (3) in 40%-60% of the volume.

2. The device for improving the yield of single-walled carbon nanotubes produced by the floating catalytic method according to claim 1, characterized in that, The outer layer of the two end conical converging furnace bodies and the cylindrical intermediate furnace body is provided with a heat preservation layer, and the outer layer of the heat preservation layer is provided with a stainless steel cover body.

3. The device for improving the yield of single-walled carbon nanotubes produced by the floating catalytic method according to claim 1, characterized in that, The high-temperature-resistant ceramic microspheres (3) are composed of one or more of silicon oxide, zirconium oxide, aluminum oxide and silicon carbide; The diameter of the high-temperature-resistant ceramic microspheres (3) is 2-10 mm, and the high-temperature-resistant ceramic microspheres (3) are filled in the two-stage heating device (2) in one or more diameters or gradually changing diameters from bottom to top.

4. The apparatus for increasing the yield of single-walled carbon nanotubes produced by a floating catalytic method according to claim 1, wherein The cooling pipeline (4) is provided with a vertical telescopic mechanism (42) for collecting products in the furnace and a gas purging device (41) for blowing the products into the product collection device (5).

5. The apparatus for increasing the yield of single-walled carbon nanotubes produced by a floating catalytic method according to claim 1, wherein The product collection device (5) is a stainless steel tank provided with a filter plate (51) with a microporous structure.

6. A method of preparing wall carbon nanotubes using the apparatus of claim 4, characterized by, The method comprises the following steps: Step one: connect the gas-liquid pipeline, and place the high-temperature-resistant ceramic microspheres (3) with a set particle size and quantity in the two-stage heating device (2); Step two: introduce inert gas to empty the air in the furnace body, and set the temperature of the two temperature zones according to the process requirements; Step three: set the temperature to be above 2 hours, and wait for the temperature of the high-temperature-resistant ceramic microspheres (3) in the furnace body to be balanced; Step four: open the gas pipeline (12) and the organic liquid carbon source precursor of the gas-liquid supply device (1), supply liquid at a certain gas flow rate and liquid supply rate, and start synthesizing single-walled carbon nanotubes; Step five: open the vertical telescopic mechanism (42) and the gas purging device (41) on the cooling pipeline, and collect the products into the cavity of the product collection device (5).

7. The method of claim 6, wherein the carbon nanotube is a wall carbon nanotube. In step two, the temperature of the lower furnace body (25) is set to 300-500 DEG C, and the temperature of the cylindrical intermediate furnace body is set to 1100-1600 DEG C.

8. The method for preparing carbon nanotubes according to claim 6, characterized in that, In step four, the gas flow is set to 5 L / min-100 L / min, and the liquid flow is set to 0.5 ml / min-20 ml / min.

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