A single-walled carbon nanotube and a preparation method thereof

Abstract

The present invention provides a single-walled carbon nanotube and a preparation method thereof. The preparation method includes: providing a supported catalyst, the supported catalyst including a catalyst, a promoter, and a porous hard carbon material, wherein the catalyst and the promoter are at least fixed in the pores of the porous hard carbon material; pyrolyzing a carbon source into carbon atoms by a plasma arc in a reaction zone, and enabling the carbon atoms to contact and react with the supported catalyst and hydrogen in the reaction zone to obtain single-walled carbon nanotubes. The preparation method provided by the present invention has a high catalytic efficiency, thereby obtaining a high yield of single-walled carbon nanotubes. At the same time, since the hard carbon material is amorphous carbon, it can be removed by heat treatment and is not likely to introduce impurities into the product. The yield of single-walled carbon nanotubes obtained by this method is greater than 100 g / h, the purity is not less than 70%, and the IG / ID of the carbon nanotubes is greater than 50.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon nanotube preparation, and particularly relates to a single-walled carbon nanotube and a preparation method thereof. Background Art

[0002] A single-walled carbon nanotube (SWCNT) is formed by arranging a single layer of carbon atoms in a hexagonal honeycomb structure to form a hollow cylinder. Its diameter is usually in the range of several nanometers, while its length can reach several micrometers or longer. Single-walled carbon nanotubes have become an ideal material for fabricating high-performance and small-size electronic devices due to their high electrical conductivity and excellent electron transport properties.

[0003] Currently, the commonly used preparation methods for single-walled carbon nanotubes mainly include chemical vapor deposition, laser ablation, and arc discharge methods. Among them, the chemical vapor deposition method has been favored by many researchers because of its simple preparation method and high purity and quality of the obtained single-walled carbon nanotubes. However, the chemical vapor deposition method has limited production and cannot produce single-walled carbon nanotubes at low cost, on a large scale, and commercially. The laser ablation method requires very high temperatures and pressures, and at the same time, the equipment is expensive and the quality is difficult to control. The arc discharge method for preparing single-walled carbon nanotubes requires simple equipment, easily available raw materials, and low costs. At the same time, the obtained carbon nanotubes have a high degree of crystallinity and is a method capable of large-scale and industrial production. However, the arc method has problems such as low catalyst utilization rate and low carbon nanotube yield. Summary of the Invention

[0004] To solve all or part of the above technical problems, the present invention provides the following technical solutions:

[0005] One of the purposes of the present invention is to provide a preparation method for single-walled carbon nanotubes, and the method includes:

[0006] Providing a supported catalyst, the supported catalyst includes a catalyst, a promoter, and a porous hard carbon material, and the catalyst and the promoter are at least fixed in the pores of the porous hard carbon material;

[0007] In a reaction zone, carbon source is cracked into carbon atoms by a plasma arc, and the carbon atoms are brought into contact with the supported catalyst and hydrogen in the reaction zone and react to obtain single-walled carbon nanotubes.

[0008] In some embodiments, the preparation method specifically includes:

[0009] Filling an inert gas in the reaction zone, heating the reaction zone to a set temperature by a plasma arc, and then inputting the carbon source into the reaction zone to crack the carbon source into the carbon atoms;

[0010] Contact the carbon atoms with the supported catalyst and hydrogen in the reaction zone and react to obtain a mixture containing single-walled carbon nanotubes.

[0011] In some embodiments, the method further includes: heat-treating the product in the presence of oxygen to remove the porous hard carbon material therein and obtain purified single-walled carbon nanotubes; wherein the temperature of the heat treatment is 400°C to 470°C.

[0012] It should be noted that the obtained mixture may also include a small amount of catalyst and cocatalyst. Generally, the catalyst and cocatalyst can be washed away by conventional hydrochloric acid soaking, for example, soaking with 2-6M hydrochloric acid for 3-5h, and then washing with water until neutral.

[0013] In some embodiments, the time of the heat treatment is 1-2h.

[0014] In some embodiments, the loading amount of the catalyst in the supported catalyst is 300-1800 mg / g, and the loading amount of the cocatalyst is 50-700 mg / g.

[0015] In some embodiments, the porous hard carbon material is an amorphous carbon material.

[0016] In some embodiments, the porous hard carbon material includes one or a combination of resin carbon materials, non-resin type organic polymer pyrolytic carbon materials, or carbon black. Among them, the resin carbon material includes, for example, phenolic resin, epoxy resin, polyfurfuryl alcohol PFA-C and other high molecular polymer pyrolysis products, but is not limited thereto. Among them, the organic polymer pyrolytic carbon includes, for example, PVA, PVC, PVDF, PAN and other pyrolytic carbons, but is not limited thereto.

[0017] In some embodiments, the porosity of the porous hard carbon material is 15-50%, and the diameter of the pores contained therein is 2-300 nm. The porous hard carbon material has a rich microporous structure, a large specific surface area, and strong adsorption for tiny particles. Therefore, a large number of catalyst and cocatalyst particles in the micro-nano size can be fixed in the pores, so as to ensure that the catalyst and cocatalyst can maintain a stable ratio before reaching the reaction zone and evaporating.

[0018] In some embodiments, the catalyst and cocatalyst are nanoscale, and the particle size is 1-100 nm. The catalyst and cocatalyst within this particle size range are more conducive to improving the yield and quality of single-walled carbon nanotubes.

[0019] In some embodiments, the catalyst includes one or a combination of iron powder, cobalt powder, nickel powder, iron oxide, cobalt oxide or nickel oxide.

[0020] In some embodiments, the cocatalyst includes elemental sulfur and / or sulfur-containing compounds.

[0021] In some embodiments, the carbon source is a gaseous carbon source. Compared with solid carbon sources, the efficiency of preparing single-walled carbon nanotubes using a gaseous carbon source is relatively high.

[0022] In some embodiments, the gaseous carbon source includes one or more combinations of methane, ethane, ethylene, acetylene, CO, etc., but is not limited thereto.

[0023] In some embodiments, the carbon source is input into the reaction zone at a flow rate of 3 - 50 L / min.

[0024] In some embodiments, hydrogen is input into the reaction zone at a flow rate of 5 - 100 L / min.

[0025] In some embodiments, a carrier gas is used to input the supported catalyst into the reaction zone, and the flow rate of the carrier gas is 1 - 10 L / min.

[0026] In some embodiments, the carrier gas includes one or more combinations of nitrogen, argon, helium, etc., but is not limited thereto.

[0027] In some embodiments, the inert atmosphere includes one or more combinations of nitrogen, argon, helium, etc., but is not limited thereto.

[0028] In some embodiments, the method sets the power of the plasma arc to be 15 - 180 kw and the arc length to be 2 - 15 cm.

[0029] In some embodiments, the temperature at which the carbon atoms react with the supported catalyst and hydrogen is 700 - 1800 °C. That is, after heating the reaction zone to 700 - 1800 °C with a plasma arc, the carbon source is input into the reaction zone to crack the carbon source into the carbon atoms, and the carbon atoms, supported catalyst, and hydrogen will react at 700 - 1800 °C.

[0030] In some embodiments, the preparation method of the supported catalyst includes: ball-milling a mixture containing the catalyst, cocatalyst, and porous hard carbon material.

[0031] In some embodiments, the mass ratio of the catalyst, cocatalyst, and porous hard carbon material in the mixture is 60 - 90:30 - 9:10 - 1.

[0032] In some embodiments, the process conditions for the ball-milling treatment include: the ball-milling speed is 100 - 500 revolutions per minute, and the ball-milling time is 1 - 2 h. The diameter of the grinding balls used is, for example, 2 mm, and the ball-to-material ratio is 1:1 - 5:1.

[0033] In some embodiments, the yield of single-walled carbon nanotubes prepared by the method provided by the present invention is above 100 g / h, and the purity of the obtained single-walled carbon nanotubes is not less than 70%.

[0034] In a typical embodiment, the method for preparing single-walled carbon nanotubes includes the following steps:

[0035] Prepare a supported catalyst by filling a nano-sized catalyst and a promoter into the pores of a porous hard carbon material;

[0036] Introduce a large amount of inert gas into the plasma arc furnace to remove the air in the reaction chamber, set the current and voltage for arc ignition to draw an arc, so as to generate an arc between the cathode and the anode, and keep the arc continuously preheating the chamber until the set temperature is reached;

[0037] Transport the carbon source gas to the arc reaction zone to crack it into carbon atoms, then transport the supported catalyst to the cracked carbon source area, and at the same time introduce hydrogen, so that the carbon atoms, the supported catalyst and hydrogen react under the action of the arc to obtain a product containing single-walled carbon nanotubes.

[0038] Another object of the present invention is to provide a single-walled carbon nanotube prepared by the method described in any one of the above technical solutions.

[0039] In some embodiments, the IG / ID of the single-walled carbon nanotubes prepared by the method is greater than 50.

[0040] Compared with the prior art, the present invention has at least the following beneficial effects:

[0041] (1) The supported catalyst adopted by the present invention can improve the catalytic activity, catalyst utilization rate and preparation efficiency of preparing single-walled carbon nanotubes by the plasma arc method;

[0042] (2) In the prior art, the catalyst and the promoter are usually transported through a gas pipeline by using an inert gas. Since the masses of the two are quite different, their transportation speeds are different during transportation, and they cannot reach the reaction zone at the required ratio at the same time. Moreover, during the reaction, the one with a larger mass is likely to sink to the bottom, that is, the "stratification phenomenon" appears. The present invention uses a porous hard carbon material to support the catalyst and the promoter, which plays a role in storing and fixing the catalyst and the promoter, can ensure the stability of the catalyst and the promoter during transportation, is not prone to the stratification phenomenon, and at the same time ensures that the two are transported to the arc zone to participate in the reaction at the same time, and can maintain a stable ratio before reaching the reaction zone and evaporating, thereby improving the utilization rate of the catalyst;

[0043] (3) The hard carbon material used in the present invention is amorphous carbon, which will not be graphitized during the plasma arc process and can exist stably. Therefore, the hard carbon material can be removed by heat-treating the product without introducing new impurities, thereby improving the purity of single-walled carbon nanotubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0045] Figure 1 It is the Raman spectrum diagram of the single-walled carbon nanotubes prepared in Example 1 of the present invention;

[0046] Figure 2 It is the thermogravimetric curve diagram of the single-walled carbon nanotubes prepared in Example 1 of the present invention;

[0047] Figure 3 It is the scanning electron microscope picture of the single-walled carbon nanotubes prepared in Example 1 of the present invention;

[0048] Figure 4 It is the transmission electron microscope picture of the single-walled carbon nanotubes prepared in Example 1 of the present invention;

[0049] Figure 5 It is the Raman spectrum diagram of the single-walled carbon nanotubes prepared in Comparative Example 1;

[0050] Figure 6 It is the thermogravimetric curve diagram of the single-walled carbon nanotubes prepared in Comparative Example 1;

[0051] Figure 7 It is the scanning electron microscope picture of the single-walled carbon nanotubes prepared in Example 3 of the present invention;

[0052] Figure 8 It is the transmission electron microscope picture of the single-walled carbon nanotubes prepared in Example 5 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] The following will specifically describe the technical solutions of the present invention in detail with reference to specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the present invention. The specific functional details disclosed herein should not be construed as restrictive, but only as the basis of the claims and as a representative basis for teaching those skilled in the art to adopt the present invention in any appropriate detailed embodiment in different ways.

[0054] Unless otherwise specified, the raw materials and reagents used in the specific embodiments of the present invention are commercially available.

[0055] Example 1

[0056] This example provides a single-walled carbon nanotube and a preparation method thereof, which are specifically completed through the following steps:

[0057] (1) Use a planetary ball mill with a 50 ml nylon ball milling tank. Add 15 agate balls with a diameter of 2 mm to it. Weigh iron powder (particle size of 20 nm), sulfur powder (particle size of 50 nm) and carbon black according to a mass ratio of 70:20:10 and add them to the ball milling tank. The addition amount reaches 1 / 3 of the capacity of the ball milling tank. Set the ball milling speed to 500 revolutions per minute and the ball milling time to 1 hour. After completion, sieve the product through a 200-mesh sieve to separate the agate balls, and obtain a supported catalyst;

[0058] (2) Continuously introduce argon into the reaction chamber of the plasma arc furnace at a flow rate of 50 L / min for 30 min to exhaust the air in the chamber. Then turn on the arc, adjust the arc power to 120 KW, the arc length to 5 cm, and preheat the reaction chamber to 1000 °C;

[0059] (3) Transport methane to the high-temperature arc zone at a flow rate of 30 L / min for rapid cracking to crack it into carbon atoms. Then, use argon at a flow rate of 5 L / min as a carrier to transport the supported catalyst prepared above to the arc reaction zone, and simultaneously introduce hydrogen at a flow rate of 10 L / min, so that carbon atoms, the supported catalyst, and hydrogen react under the action of the arc for 60 min to obtain 150 g of a product containing single-walled carbon nanotubes.

[0060] Raman spectroscopy is an effective method for evaluating the quality of single-walled carbon nanotubes. Figure 1 It is the Raman spectrogram obtained by Raman detection of the single-walled carbon nanotubes obtained in this example. Raman detection is carried out at a laser wavelength of 532 nm. It can be observed that at a wavelength of 1580 cm -1 there is a G peak reflecting the integrity of the SP2 hybrid bond structure, and at 1340 cm -1 there is a D peak related to the incompleteness of microcrystals and structural defects. By calculating the intensity ratio I G / I D , the integrity of the graphite structure of the carbon nanotubes can be judged. By calculating I G / I D to be 66, it shows a high degree of crystallinity.

[0061] Thermogravimetric detection can be used to characterize the product purity. In air, heat the product to 900 °C. As time goes by, the carbon materials in the product are continuously oxidized and exhausted. Finally, the purity of the carbon nanotubes in the sample is deduced from the remaining catalyst mass. As shown in Figure 2 the thermogravimetry, it is calculated that the purity of the single-walled carbon nanotubes is 70%.

[0062] Figure 3 This is a scanning electron microscope image of the single-walled carbon nanotubes prepared in this example. Figure 4 This is a transmission electron microscope image of the single-walled carbon nanotubes prepared in this example.

[0063] Example 2

[0064] This example provides a single-walled carbon nanotube and its preparation method, which are specifically completed through the following steps:

[0065] (1) Use a planetary ball mill with a 50 ml nylon ball milling jar. Add 15 agate balls with a diameter of 2 mm to it. Weigh nickel powder, sulfur powder, and resin carbon (purchased from Taiyuan Cuixiong Technology Co., Ltd.) according to a mass ratio of 80:15:5, and add them to the ball milling jar until the addition amount reaches 1 / 3 of the capacity of the ball milling jar. Set the ball milling speed at 100 revolutions per minute and the ball milling time at 2 hours. After completion, sieve the product through a 200-mesh sieve to separate the agate balls and obtain the supported catalyst.

[0066] (2) Continuously introduce argon into the reaction chamber of the plasma arc furnace at a flow rate of 60 L / min for 30 min to exhaust the air in the chamber. Then turn on the arc, adjust the arc power to 130 KW, the arc length to 6 cm, and preheat the reaction chamber to 1000 °C.

[0067] (3) Transport methane to the high-temperature arc zone at a flow rate of 30 L / min for rapid cracking to make it crack into carbon atoms. Then, use argon at a flow rate of 5 L / min as the carrier gas to transport the supported catalyst prepared above to the arc reaction zone, and at the same time introduce hydrogen at a flow rate of 10 L / min to make the carbon atoms, supported catalyst, and hydrogen react under the action of the arc for 60 min to obtain 115 g of the product.

[0068] In air, heat-treat the product obtained above at 450 °C for 1.5 h to remove a small amount of resin carbon mixed in the product and obtain 101 g of pure single-walled carbon nanotubes.

[0069] Figure 7 This is a scanning electron microscope image of the single-walled carbon nanotubes prepared in Example 3.

[0070] Example 3

[0071] This example provides a single-walled carbon nanotube and its preparation method, which are specifically completed through the following steps:

[0072] (1) Use a planetary ball mill with a 50 ml nylon ball mill pot. Add 15 agate balls with a diameter of 2 mm to it. Weigh cobalt powder, sulfur powder, and carbon black according to a mass ratio of 75:17:8, and add them to the ball mill pot. The addition amount reaches 1 / 3 of the capacity of the ball mill pot. Set the ball milling speed at 300 revolutions per minute and the ball milling time at 1.5 hours. After completion, sieve the product through a 200-mesh sieve to separate the agate balls, and obtain the supported catalyst;

[0073] (2) Continuously introduce argon into the reaction chamber of the plasma arc furnace at a flow rate of 60 L / min for 30 min to exhaust the air in the chamber. Then turn on the arc, adjust the arc power to 140 KW, and the arc length to 8 cm. Preheat the reaction chamber to 1200 °C;

[0074] (3) Transport methane to the high-temperature arc zone at a flow rate of 20 L / min for rapid cracking to crack it into carbon atoms. Then, use 5 L / min argon as the carrier to transport the supported catalyst prepared above to the arc reaction zone. At the same time, introduce hydrogen at a flow rate of 30 L / min, so that carbon atoms, the supported catalyst, and hydrogen react under the action of the arc for 60 min to obtain 126 g of the product.

[0075] In air, heat-treat the product obtained above at 400 °C for 2 h to remove a small amount of carbon black mixed in the product and obtain 108 g of pure single-walled carbon nanotubes. Example 4

[0076] This example provides a single-walled carbon nanotube and its preparation method, which are specifically completed through the following steps:

[0077] (1) Use a planetary ball mill with a 50 ml nylon ball mill pot. Add 15 agate balls with a diameter of 2 mm to it. Weigh iron powder, sulfur powder, and resin carbon (purchased from Taiyuan Cuihong Technology Co., Ltd.) according to a mass ratio of 65:25:10, and add them to the ball mill pot. The addition amount reaches 1 / 3 of the capacity of the ball mill pot. Set the ball milling speed at 500 revolutions per minute and the ball milling time at 1.5 hours. After completion, sieve the product through a 200-mesh sieve to separate the agate balls, and obtain the supported catalyst;

[0078] (2) Continuously introduce argon into the reaction chamber of the plasma arc furnace at a flow rate of 40 L / min for 30 min to exhaust the air in the chamber. Then turn on the arc, adjust the arc power to 110 KW, and the arc length to 5 cm. Preheat the reaction chamber to 1500 °C;

[0079] (3) Methane was transported to the high-temperature arc zone at a flow rate of 30 L / min for rapid pyrolysis to produce carbon atoms. Then, using 7 L / min of argon as the carrier gas, the above-prepared supported catalyst was transported to the arc reaction zone, and hydrogen was introduced at a flow rate of 25 L / min. Thus, the carbon atoms, supported catalyst, and hydrogen reacted under the action of the arc for 60 min to obtain 103 g of the product.

[0080] In air, the above-obtained product was heat-treated at 470 °C for 2 h to remove a small amount of carbon black mixed in the product, and 86 g of pure single-walled carbon nanotubes was obtained.

[0081] Figure 8 It is a transmission electron microscope image of the single-walled carbon nanotubes prepared in Example 5. Example 5

[0082] This example provides a single-walled carbon nanotube and its preparation method, which are specifically completed through the following steps:

[0083] (1) Using a planetary ball mill with a 50 ml nylon ball milling jar, 15 agate balls with a diameter of 2 mm were added to it. Iron powder, sulfur powder, and pyrolytic carbon of organic polymer (purchased from Tianjin Yihuilong Chemical Technology Co., Ltd.) were weighed according to a mass ratio of 60:30:10 and added to the ball milling jar. The addition amount reached 1 / 3 of the capacity of the ball milling jar. The ball milling speed was set at 500 revolutions per minute, and the ball milling time was 1 hour. After completion, the product was sieved through a 200-mesh sieve to separate the agate balls, and the supported catalyst was obtained.

[0084] (2) Argon was continuously introduced into the reaction chamber of the plasma arc furnace at a flow rate of 50 L / min for 30 min to exhaust the air in the chamber. Then, the arc was turned on, the arc power was adjusted to 15 KW, the arc length was 2 cm, and the reaction chamber was preheated to 700 °C.

[0085] (3) Ethylene was transported to the high-temperature arc zone at a flow rate of 3 L / min for rapid pyrolysis to produce carbon atoms. Then, using 1 L / min of argon as the carrier, the above-prepared supported catalyst was transported to the arc reaction zone, and hydrogen was introduced at a flow rate of 5 L / min. Thus, the carbon atoms, supported catalyst, and hydrogen reacted under the action of the arc for 60 min to obtain a product containing single-walled carbon nanotubes. Example 6

[0086] This example provides a single-walled carbon nanotube and its preparation method, which are specifically completed through the following steps:

[0087] (1) A planetary ball mill with a 50 ml nylon ball mill pot was used. 15 agate balls with a diameter of 2 mm were added to it. Iron powder, sulfur powder and pyrolytic carbon of organic polymer (purchased from Tianjin Yihuilong Chemical Technology Co., Ltd.) were weighed according to the mass ratio of 90:10:1 and added to the ball mill pot. The addition amount reached 1 / 3 of the capacity of the ball mill pot. The ball milling speed was set at 500 revolutions per minute and the ball milling time was 1 hour. After completion, the product was passed through a 200-mesh sieve to separate the agate balls, and a supported catalyst was obtained.

[0088] (2) Argon was continuously introduced into the reaction chamber of the plasma arc furnace at a flow rate of 50 L / min for 30 min to exhaust the air in the chamber. Then the arc was turned on, the arc power was adjusted to 180 KW, the arc length was 15 m, and the reaction chamber was preheated to 1800 °C.

[0089] (3) CO was transported to the high-temperature arc zone at a flow rate of 50 L / min for rapid cracking to form carbon atoms. Then, using 10 L / min argon as the carrier, the supported catalyst prepared above was transported to the arc reaction zone, and hydrogen was introduced at a flow rate of 100 L / min at the same time, so that the carbon atoms, supported catalyst and hydrogen reacted under the action of the arc for 60 min to obtain a product containing single-walled carbon nanotubes.

[0090] Comparative Example 1

[0091] Comparative Example 1 was basically the same as Example 1, and the difference was only that carbon black was not used to support iron powder and sulfur powder. The specific steps were as follows:

[0092] (1) A planetary ball mill with a 50 ml nylon ball mill pot was used. 15 agate balls with a diameter of 2 mm were added to it. Iron powder (particle size 20 nm) and sulfur powder (particle size 50 nm) were weighed according to the mass ratio of 80:20 and added to the ball mill pot. The addition amount reached 1 / 3 of the capacity of the ball mill pot. The ball milling speed was set at 500 revolutions per minute and the ball milling time was 1 hour. After completion, the product was passed through a 200-mesh sieve to separate the agate balls, and a supported catalyst was obtained.

[0093] (2) Argon was continuously introduced into the reaction chamber of the plasma arc furnace at a flow rate of 50 L / min for 30 min to exhaust the air in the chamber. Then the arc was turned on, the arc power was adjusted to 120 KW, the arc length was 5 cm, and the reaction chamber was preheated to 1000 °C.

[0094] (3) Methane was transported to the high-temperature arc zone at a flow rate of 30 L / min for rapid cracking to form carbon atoms. Then, using 5 L / min argon as the carrier, the mixture of iron powder and sulfur powder prepared above was transported to the arc reaction zone, and hydrogen was introduced at a flow rate of 10 L / min at the same time, so that the carbon atoms, mixture and hydrogen reacted under the action of the arc for 60 min to obtain 80 g of product.

[0095] Figure 5 is the Raman spectrum of the single-walled carbon nanotubes prepared in Comparative Example 1. By calculation, I G / I D is 45. Figure 6 is the thermogravimetric curve of the single-walled carbon nanotubes prepared in Comparative Example 1, with a residual mass of 41.96%.

[0096] Comparative Example 2

[0097] (1) Weigh iron powder, sulfur powder and resin carbon at a mass ratio of 65:25:10 respectively, place them in a container and shake well to obtain a uniformly mixed mixture;

[0098] (2) Continuously introduce argon into the reaction chamber of the plasma arc furnace at a flow rate of 40 L / min for 30 min to exhaust the air in the chamber. Then turn on the arc, adjust the arc power to 110 KW, the arc length to 5 cm, and preheat the reaction chamber to 1500 °C;

[0099] (3) Transport methane to the high-temperature arc zone at a flow rate of 30 L / min for rapid cracking to crack it into carbon atoms. Then, use argon at a flow rate of 7 L / min as the carrier gas to transport the above-prepared mixture to the arc reaction zone, and simultaneously introduce hydrogen at a flow rate of 25 L / min to allow the carbon atoms, supported catalyst, and hydrogen to react under the action of the arc for 60 min to obtain 15 grams of product.

[0100] By calculation, I G / I D is 5. The residual mass by thermogravimetric analysis is 43.2%. The product contains a large amount of amorphous carbon.

[0101] All aspects, embodiments, features and examples of the present invention should be considered illustrative in all respects and are not intended to limit the present invention. The scope of the present invention is only defined by the claims. Without departing from the spirit and scope of the claimed invention, those skilled in the art will understand other embodiments, modifications and uses.

[0102] In addition, the inventors of this case also referred to the foregoing embodiments and conducted tests with other raw materials, process operations and process conditions described in this specification, and all obtained relatively ideal results.

[0103] Although the present invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions and / or additions can be made without departing from the spirit and scope of the present invention, and elements of the embodiments can be replaced with materially equivalent ones. In addition, many modifications can be made without departing from the scope of the present invention to adapt a particular situation or material to the teachings of the present invention. Therefore, the present invention is not intended to be limited to the specific embodiments disclosed for carrying out the present invention, but is intended to cover all embodiments falling within the scope of the appended claims. In addition, unless specifically stated, any use of the terms first, second, etc. does not denote any order or importance, but the terms first, second, etc. are used to distinguish one element from another element.

Claims

1. A method for preparing single-walled carbon nanotubes, characterized in that: include: Provided is a supported catalyst, the supported catalyst comprising a catalyst, a co-catalyst and a porous hard carbon material, wherein the porous hard carbon material is an amorphous carbon material selected from at least one of a resin carbon material, a non-resin organic polymer pyrolysis carbon material or carbon black, and has a porosity of 15-50%, and a diameter of pores contained therein of 2-300 nm; the catalyst and the co-catalyst are nanoscale, with a particle size of 1-100 nm, and both are fixed in the pores of the porous hard carbon material at least, and the loading amounts of the catalyst and the co-catalyst are 30 0~1800mg / g, 50~700mg / g, the catalyst is selected from one or more of iron powder, cobalt powder, nickel powder, iron oxide, cobalt oxide or nickel oxide, and the cocatalyst is selected from sulfur and / or sulfur-containing compounds; wherein the preparation method of the supported catalyst comprises: ball milling a mixture of the catalyst, the cocatalyst and the porous hard carbon material in a mass ratio of 60~90:30~9:10~1, the ball milling speed is 100~500 rpm, and the ball milling time is 1~2h; The reaction zone is filled with an inert gas and heated to a set temperature by a plasma arc, wherein the power of the plasma arc is 15-180 kw and the arc length is 2-15 cm; then a carbon source is introduced into the reaction zone to decompose the carbon source into carbon atoms; The supported catalyst is introduced into the reaction zone by using a carrier gas, so that the carbon atoms are contacted with the supported catalyst and hydrogen in the reaction zone and react at 700-1800° C. to obtain a mixture containing single-walled carbon nanotubes; The mixture is heat treated at 400° C. to 470° C. in the presence of oxygen to remove the porous hard carbon material therein and obtain purified single-walled carbon nanotubes.

2. The preparation method according to claim 1, characterized in that: The carbon source is a gaseous carbon source.

3. The preparation method according to claim 2, characterized in that: The gaseous carbon source includes one or a combination of methane, ethane, ethylene, acetylene, and CO.

4. The preparation method according to claim 1, characterized in that: The carbon source is fed into the reaction zone at a flow rate of 3-50 L / min.

5. The preparation method according to claim 1, characterized in that: The hydrogen is introduced into the reaction zone at a flow rate of 5-100 L / min.

6. The preparation method according to claim 1, characterized in that: The flow rate of the carrier gas is 1-10 L / min.

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