Device and method for preparing single-walled carbon nanotubes

Abstract

The invention discloses a device and a method for preparing a single-walled carbon nanotube, and belongs to the technical field of carbon nanotubes. A floating catalysis method and a plasma method are combined, and a plasma instantaneous high-temperature vaporization catalyst is used; the catalyst is easy to generate atom agglomeration after being vaporized to form clusters, so that the distance between the plasma generation area and the synthesis area is controlled at the same time to control the cluster size of catalyst particles, and specifically, the distance between the plasma generation area and the synthesis area is controlled to be a relatively short distance; the growth of the particle size of the catalyst can be reduced, so that a large number of catalyst particles can be prepared, and the yield of the single-walled carbon nanotube is increased; in addition, a carbon source is introduced into the carbon source mixing and connecting region, and the carbon source and catalyst particles are mixed in advance, so that the carbon source is in uniform contact with the catalyst, the carbon yield can be improved, and the synthesis efficiency of the single-walled carbon nanotube is improved.

Description

Technical Field

[0001] This application relates to the field of carbon nanotube technology, and in particular to an apparatus and method for preparing single-walled carbon nanotubes. Background Technology

[0002] Currently, the commonly used method for preparing single-walled carbon nanotubes is the floating catalysis method, which produces products of high quality. However, this method typically involves synthesizing the catalyst and carbon source in the same region, making it difficult to control the catalyst size and synthesis time. This leads to catalyst agglomeration and growth during the synthesis process, limiting yield improvement. Therefore, how to increase the yield of single-walled carbon nanotubes is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0003] The purpose of this application is to provide an apparatus and method for preparing single-walled carbon nanotubes, which can realize the batch preparation of single-walled carbon nanotubes, improve the yield, and produce single-walled carbon nanotubes with high yield, good quality and high G / D ratio.

[0004] To achieve the above objectives, this application provides an apparatus for preparing single-walled carbon nanotubes, comprising: a plasma generation region, a carbon source mixing and connection region, and a synthesis region connected in sequence;

[0005] The plasma generation zone includes a cathode, a first insulating layer, a first anode, a second insulating layer, and a second anode arranged sequentially; a first gas inlet pipe is provided between the cathode and the first anode; and a catalyst feed pipe is provided between the first anode and the second anode.

[0006] The distance between the end of the carbon source mixing and connection region that connects to the plasma generation region and the end of the carbon source mixing and connection region that connects to the synthesis region is 1cm-10cm, including the values ​​at both ends; the carbon source mixing and connection region is provided with a carbon source inlet.

[0007] Optionally, a first through hole is provided in the first insulating layer;

[0008] The first anode has a groove on the side facing the cathode; one end of the cathode is inserted into the groove through the first through hole; a second through hole is provided at the bottom of the groove; the first gas inlet pipe passes through the side wall of the groove and extends into the groove.

[0009] Optionally, a third through hole is provided in the second insulating layer; the catalyst feed pipe passes through the sidewall of the third through hole and extends into the interior of the third through hole;

[0010] The diameter of the second anode is larger than the diameter of the projection of the first anode onto the second anode; a fourth through hole is provided in the second anode; the second through hole, the third through hole, the fourth through hole and the carbon source mixing and connection region are connected in sequence.

[0011] Optionally, the plasma generating region further includes a connector; one end of the connector is connected to the cathode, and the other end is connected to the second anode; the cathode, the connector, and the second anode enclose a cavity; the first insulating layer, the first anode, and the second insulating layer are located within the cavity.

[0012] Optionally, the carbon source inlet and the carbon source feed pipeline are connected; the carbon source feed pipeline includes a first preheater and a first flow control device arranged sequentially in a direction away from the carbon source mixing and connection area.

[0013] Optionally, the carbon source mixing and connection region is provided with a second gas inlet;

[0014] The second gas inlet is connected to the second gas inlet pipeline; the second gas inlet pipeline includes a second preheater and a second flow control device arranged sequentially in a direction away from the carbon source mixing and connection area.

[0015] Optionally, the apparatus for preparing single-walled carbon nanotubes further includes: a collection zone; the collection zone includes a collection chamber and a receiving shaft; the collection chamber is connected to the synthesis zone; one end of the receiving shaft is inserted into the collection chamber.

[0016] Optionally, the diameter of the carbon source mixing and connection region is smaller than the diameter of the synthesis region.

[0017] Optionally, the diameter of the synthesis zone is 5cm-50cm, including the values ​​at both ends.

[0018] To achieve the above objectives, this application also provides a method for preparing single-walled carbon nanotubes, using the apparatus described above for preparing single-walled carbon nanotubes, comprising:

[0019] A first gas is introduced between the cathode and the first anode to generate a first plasma. Then, the gas is introduced between the first anode and the second anode to generate a second plasma. The temperature of the second plasma is higher than that of the first plasma.

[0020] The catalyst is introduced between the first anode and the second anode, and after the catalyst forms catalyst particles under the action of the second plasma, it is introduced into the carbon source mixing and connection region; the pyrolysis time of the catalyst particles in the carbon source mixing and connection region is less than 100ms.

[0021] A carbon source is introduced into the carbon source mixing and connection region, and the carbon source is mixed with the catalyst particles and then introduced into the synthesis region to synthesize the single-walled carbon nanotubes.

[0022] Optionally, introducing the carbon source into the carbon source mixing and bonding region includes:

[0023] The mixture of the accelerator and the carbon source is preheated and then introduced into the carbon source mixing and bonding region;

[0024] Alternatively, the promoter and the carbon source can be preheated separately and then introduced into the carbon source mixing and bonding region.

[0025] Optionally, the method for preparing single-walled carbon nanotubes further includes: preheating a second gas and then introducing it into the carbon source mixing and connection region.

[0026] Optionally, the size of the catalyst particles introduced into the synthesis zone is 1 nm to 10 nm, including the values ​​at both ends.

[0027] Obviously, the apparatus for preparing single-walled carbon nanotubes provided in this application has the following advantages compared with the prior art:

[0028] (1) The cathode and the first anode are mainly used to initiate the arc, thereby achieving plasmaification of the first gas. After the arc is initiated, the cathode and the first anode, along with the second anode, are used to extend the arc, enabling the plasma velocity of the first gas to reach subsonic speeds and achieving instantaneous temperatures of 600℃-5000℃. The catalyst is fed between the first and second anodes, and the catalyst is vaporized by plasma at high temperatures, which can generate ultrafine catalyst particles.

[0029] (2) Since catalyst particles are prone to aggregation at high temperatures, if carbon nanotubes cannot be synthesized before aggregation, the catalyst particles will grow and fail, or combine with the carbon source, causing the carbon source to encapsulate the catalyst particles and fail. Therefore, by controlling the distance from the plasma generation region to the synthesis region where the catalyst particles are formed to be 1cm-10cm, the pyrolysis time of the catalyst particles in the carbon source mixing and connection region can be controlled to be less than 100ms. A smaller pyrolysis time can prevent the catalyst particles from growing and is conducive to the generation of smaller catalyst particles. In this way, a large number of catalyst particles can be prepared, thereby increasing the yield of single-walled carbon nanotubes.

[0030] (3) Introducing carbon source into the carbon source mixing and connection zone allows the carbon source to achieve a certain mixing effect with the catalyst particles here, and achieves a relative mixing effect before entering the synthesis zone for synthesis, so as to achieve uniform contact between carbon source and catalyst, which can improve carbon yield and increase the synthesis efficiency of single-walled carbon nanotubes.

[0031] (4) The above scheme can not only realize the batch preparation of single-walled carbon nanotubes and improve the yield, but also produce single-walled carbon nanotubes with high yield, good quality and high G / D ratio.

[0032] This application also provides a method for preparing single-walled carbon nanotubes, which uses the above-described apparatus for preparing single-walled carbon nanotubes and has the same beneficial effects. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0034] Figure 1 A schematic diagram of an apparatus for preparing single-walled carbon nanotubes provided in an embodiment of this application;

[0035] Figure 2 A flowchart illustrating a method for preparing single-walled carbon nanotubes provided in this application embodiment;

[0036] Figure 3 An SEM image of a single-walled carbon nanotube powder prepared according to an embodiment of this application;

[0037] Figure 4 A TEM image of a single-walled carbon nanotube powder prepared according to an embodiment of this application;

[0038] Figure 5 The Raman spectrum of a single-walled carbon nanotube powder prepared according to an embodiment of this application is provided.

[0039] Figure 6 This is a schematic diagram of thermogravimetric analysis of a single-walled carbon nanotube powder prepared according to an embodiment of this application.

[0040] The annotations in the attached figures are explained as follows:

[0041] 1-Cathode; 2-First insulating layer; 3-First gas inlet pipe; 4-First anode; 5-Second insulating layer; 6-Catalyst feed pipe; 7-Second anode; 81-First flow control device; 82-Second flow control device; 91-First preheater; 92-Second preheater; 10-Carbon source feed pipe; 11-Second gas inlet pipe; 12-Synthesis furnace; 131-Collection bin; 132-Collection shaft. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0043] Currently, the most likely methods for mass production of single-walled carbon nanotubes are the electric arc method and the floating catalysis method. The electric arc method requires complex equipment and yields higher output, but the product has a relatively high impurity content. Carbon nanotubes prepared using floating catalysis have higher quality products, but lower yields.

[0044] One major challenge limiting the yield of floating catalysts is the preparation of high-concentration, small-particle-size catalysts. Current synthesis processes involve the pyrolysis of the catalyst and carbon source within the same region, making it difficult to effectively control catalyst size and synthesis time in the reactor. This results in prolonged catalyst growth, particle agglomeration, and a mismatch between catalyst particle size and yield. The key is to achieve instantaneous vaporization to generate catalyst particles, enabling carbon nanotube growth before the particles grow and deactivate, thereby increasing yield.

[0045] Currently, plasma methods are the most promising way to improve the yield of single-walled carbon nanotubes (SHU). This method can achieve ultra-high temperatures instantaneously, with ultra-short catalyst vaporization time, and the particle size is more conducive to SHU growth. Current plasma methods mainly include DC arc, radio frequency, and microwave. Among them, DC arc has the highest temperature and allows for smaller catalyst particle size. DC arc is further divided into transferred arc and non-transferred arc methods. In the transferred arc method, due to the external anode and cathode, the arc is prone to segmentation during carbon nanotube growth, making continuous control difficult. In the non-transferred arc method, the anode and cathode are internal, making it less susceptible to external interference and resulting in more stable arc operation during growth.

[0046] Therefore, this application provides an apparatus and method for preparing single-walled carbon nanotubes, combining a floating catalysis method with a plasma method, using plasma to instantaneously vaporize the catalyst at high temperature. Since the catalyst is prone to atomic aggregation after vaporization, forming clusters, the distance between the plasma generation zone and the synthesis zone is controlled to control the cluster size of the catalyst particles. Specifically, by controlling the distance between the plasma generation zone and the synthesis zone to a relatively short distance, the growth of the catalyst particles can be reduced, thus enabling the preparation of a large number of catalyst particles and increasing the yield of single-walled carbon nanotubes. In addition, a carbon source is introduced into the carbon source mixing and connection zone, and the carbon source is pre-mixed with the catalyst particles to achieve uniform contact between the carbon source and the catalyst, which can improve the carbon yield and increase the synthesis efficiency of single-walled carbon nanotubes.

[0047] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a device for preparing single-walled carbon nanotubes provided in an embodiment of this application. The device may include: a plasma generation region, a carbon source mixing and connection region, and a synthesis region connected in sequence.

[0048] The plasma generation zone includes a cathode 1, a first insulating layer 2, a first anode 4, a second insulating layer 5, and a second anode 7 arranged sequentially; a first gas inlet pipe 3 is provided between the cathode 1 and the first anode 4; and a catalyst feed pipe 6 is provided between the first anode 4 and the second anode 7.

[0049] The distance between the end of the carbon source mixing and connection region that connects to the plasma generation region and the end of the carbon source mixing and connection region that connects to the synthesis region is 1cm-10cm, including the values ​​at both ends; the carbon source mixing and connection region is provided with a carbon source inlet.

[0050] It should be noted that in this embodiment, a cathode 1 and a first anode 4 are provided in the plasma generation zone to realize arc ignition (from no arc to arc). A first insulating layer 2 is provided between the cathode 1 and the first anode 4 to prevent short circuit between the cathode 1 and the first anode 4.

[0051] This embodiment does not limit the specific structure of the first insulating layer 2, which can be determined based on the specific structures of the cathode 1 and the first anode 4, as long as isolation between the cathode 1 and the first anode 4 can be achieved. For example, the first insulating layer 2 can have a first through hole, that is, the first insulating layer 2 can be annular. This embodiment does not limit the specific size of the first insulating layer 2, which can be determined based on the specific structures of the cathode 1 and the first anode 4, as long as isolation between the cathode 1 and the first anode 4 can be achieved. For example, the diameter of the first insulating layer 2 can be equal to or greater than the diameter of the projection of the first anode 4 onto the first insulating layer 2.

[0052] This embodiment does not limit the specific structure of the first anode 4, which can be determined according to the specific structure of the cathode 1, as long as it can achieve arc ignition. For example, a groove can be provided on the side of the first anode 4 facing the cathode 1, that is, the first anode 4 can be barrel-shaped and the opening faces the cathode 1; a second through hole can be provided at the bottom of the groove.

[0053] This embodiment does not limit the specific structure of the cathode 1, which can be determined according to the specific structure of the first anode 4, as long as it can achieve arc ignition. For example, one end of the cathode 1 can be inserted into the interior of the groove through the first through hole, that is, the cathode 1 can include a first part extending along the first direction; the first direction is parallel to the depth direction of the groove.

[0054] This embodiment does not limit the specific location of the first gas inlet pipe 3, as long as it can ensure that the first gas can be introduced between the cathode 1 and the first anode 4. For example, the first gas inlet pipe 3 can penetrate the side wall of the groove and extend into the interior of the groove.

[0055] It should be noted that in this embodiment, the plasma generation area is based on the whole composed of cathode 1 and first anode 4, and a second anode 7 is further provided. The whole composed of cathode 1 and first anode 4 and the second anode 7 are used to realize arc pulling (i.e. increase the arc power). A second insulating layer 5 is provided between the first anode 4 and the second anode 7 to prevent short circuit between the first anode 4 and the second anode 7.

[0056] This embodiment does not limit the specific structure of the second insulating layer 5. It can be determined based on the specific structures of the first anode 4 and the second anode 7, as long as isolation between the first anode 4 and the second anode 7 can be achieved. For example, a third through hole can be provided in the second insulating layer 5, that is, the second insulating layer 5 can be annular. This embodiment does not limit the specific size of the second insulating layer 5. It can be determined based on the specific structures of the first anode 4 and the second anode 7, as long as isolation between the first anode 4 and the second anode 7 can be achieved. For example, the diameter of the second insulating layer 5 can be equal to or greater than the diameter of the projection of the first anode 4 onto the second insulating layer 5.

[0057] This embodiment does not limit the specific structure of the second anode 7, and it can be determined according to the specific structure of the first anode 4, as long as arcing can be achieved. For example, the diameter of the second anode 7 can be larger than the diameter of the projection of the first anode 4 onto the second anode 7; a fourth through hole can be provided in the second anode 7. The second through hole, the third through hole, the fourth through hole and the carbon source mixing and connection region are connected in sequence.

[0058] It should be noted that, in this embodiment, after the arcing between the cathode 1 and the first anode 4 and the second anode 7 is completed, the temperature between the first anode 4 and the second anode 7 is higher. Introducing the catalyst into this area is beneficial for the complete decomposition of the catalyst, thereby obtaining smaller catalyst particles. This embodiment does not limit the specific location of the catalyst feed pipe 6, as long as it can ensure that the second gaseous catalyst can be introduced between the first anode 4 and the second anode 7. For example, the catalyst feed pipe 6 can penetrate the sidewall of the third through hole and extend into the interior of the third through hole.

[0059] Furthermore, in this embodiment, the catalyst feed line 6 may also include a third flow control device. It should be noted that the third flow control device is used to control the amount of catalyst fed. This embodiment does not limit the specific type of the third flow control device, as long as it can control the amount of catalyst fed. For example, the third flow control device may include a precision injection pump or a precision powder feeder.

[0060] It should be noted that in this embodiment, the cathode 1, the first anode 4, and the second anode 7 need to be electrically connected to the plasma power supply so that the plasma power supply can provide electrical energy with specific parameters to the cathode 1, the first anode 4, and the second anode 7.

[0061] In this embodiment, cathode 1, first insulating layer 2, first anode 4, second insulating layer 5, and second anode 7 are arranged sequentially. Preferably, cathode 1, first insulating layer 2, first anode 4, second insulating layer 5, and second anode 7 can be arranged in parallel.

[0062] Furthermore, in this embodiment, the plasma generating region may also include a connector; one end of the connector is connected to the cathode 1, and the other end is connected to the second anode 7; the cathode 1, the connector, and the second anode 7 enclose a cavity; the first insulating layer 2, the first anode 4, and the second insulating layer 5 are located within the cavity. Preferably, the cathode 1 may also include a second portion extending along a second direction; the second direction is perpendicular to the depth direction of the groove; the first portion and the second portion are connected; one end of the connector is connected to the second portion of the cathode 1. It should be noted that this embodiment adopts a non-transfer arc method, with the anode and cathode internally integrated, making it less susceptible to external interference, and resulting in more stable arc operation during growth.

[0063] It should be noted that, in this embodiment, the carbon source inlet of the carbon source mixing and connection zone is used to introduce the carbon source. The carbon source mixing and connection zone is used to achieve mixing of the carbon source and the catalyst particles.

[0064] In this embodiment, the length of the carbon source mixing connection region is equal to the distance from the end of the carbon source mixing connection region connected to the plasma generation region to the end of the carbon source mixing connection region connected to the synthesis region. That is, the length of the carbon source mixing connection region can be 1cm-10cm, including the values ​​at both ends.

[0065] In this embodiment, the diameter of the carbon source mixing and connection region can be smaller than the diameter of the synthesis region. It should be noted that having a smaller diameter in the carbon source mixing and connection region than the synthesis region increases the flow velocity of the catalyst particles within the region; a faster flow velocity helps prevent catalyst particle growth. This embodiment does not limit the specific value of the diameter of the carbon source mixing and connection region; it can be determined based on the specific diameter of the synthesis region.

[0066] Furthermore, in this embodiment, the carbon source inlet can be connected to the carbon source feed pipeline 10; the carbon source feed pipeline 10 may include a first preheater 91 and a first flow control device 81 arranged sequentially in a direction away from the carbon source mixing and connection area. It should be noted that, in this embodiment, after the carbon source inlet and the carbon source feed pipeline 10 are connected, the input end of the first flow control device 81 can be used as the carbon source inlet, and the carbon source and / or accelerator can be introduced from the input end of the first flow control device 81. The first flow control device 81 is used to control the feeding amount of the carbon source and / or accelerator. The first preheater 91 is used to preheat the carbon source and / or accelerator.

[0067] This embodiment does not limit the specific type of the first preheater 91, as long as it can perform heating.

[0068] This embodiment does not limit the specific type of the first flow control device 81, as long as it can control the amount of carbon source and / or accelerator fed. For example, the first flow control device 81 may include a precision injection pump or a gas proton flow meter.

[0069] Furthermore, in this embodiment, the carbon source mixing and connection region may be provided with a second gas inlet. It should be noted that the second gas inlet is used to introduce a second gas. The carbon source mixing and connection region is used to achieve mixing of the second gas, the carbon source, and the catalyst particles.

[0070] Furthermore, in this embodiment, the second gas inlet can be connected to the second gas inlet pipe 11; the second gas inlet pipe 11 may include a second preheater 92 and a second flow control device 82 arranged sequentially along the direction away from the carbon source mixing and connection area. It should be noted that, in this embodiment, after the second gas inlet and the second gas inlet pipe 11 are connected, the input end of the second flow control device 82 can be used as the second gas inlet, and the second gas can be introduced from the input end of the second flow control device 82. The second flow control device 82 is used to control the flow rate of the second gas. The second preheater 92 is used to preheat the second gas.

[0071] This embodiment does not limit the specific type of the second preheater 92, as long as it can perform heating.

[0072] This embodiment does not limit the specific type of the second flow control device 82, as long as it can control the flow rate of the second gas. For example, the second flow control device 82 may include a gas proton flow meter.

[0073] It should be noted that in this embodiment, the synthesis zone is used to synthesize single-walled carbon nanotubes. After the carbon source and catalyst particles are mixed in the carbon source mixing and connecting zone, they are introduced into the synthesis zone to react and thus synthesize single-walled carbon nanotubes.

[0074] This embodiment does not limit the specific structure of the synthesis zone, as long as it can provide the required temperature for synthesizing single-walled carbon nanotubes. For example, the synthesis zone may include a synthesis furnace 12 and a heating device surrounding the synthesis furnace 12.

[0075] This embodiment does not limit the specific size of the synthesis zone. Preferably, the diameter of the synthesis zone can be 5cm-50cm, including the values ​​at both ends. It should be noted that, in this embodiment, the diameter of the synthesis zone can specifically be the diameter of the synthesis furnace 12. By making the diameter of the carbon source mixing and connection zone smaller than the diameter of the synthesis furnace 12, the flow rate of the catalyst particles in the carbon source mixing and connection zone can be increased.

[0076] Furthermore, the apparatus for preparing single-walled carbon nanotubes in this embodiment may further include: a collection zone; the collection zone includes a collection chamber 131 and a receiving shaft 132; the collection chamber 131 is connected to the synthesis zone; one end of the receiving shaft 132 is inserted into the collection chamber 131. This embodiment does not limit the specific location of the collection chamber 131, as long as it can collect the synthesized single-walled carbon nanotubes. For example, the collection chamber 131 can be located at the tail of the synthesis furnace 12.

[0077] Based on the above embodiments, this application has the following beneficial effects compared with the prior art:

[0078] (1) The cathode and the first anode are mainly used to initiate the arc, thereby achieving plasmaification of the first gas. After the arc is initiated, the cathode and the first anode, along with the second anode, are used to extend the arc, enabling the plasma velocity of the first gas to reach subsonic speeds and achieving instantaneous temperatures of 600℃-5000℃. The catalyst is fed between the first and second anodes, and the catalyst is vaporized by plasma at high temperatures, which can generate ultrafine catalyst particles.

[0079] (2) Since catalyst particles are prone to aggregation at high temperatures, if carbon nanotubes cannot be synthesized before aggregation, the catalyst particles will grow and fail, or combine with the carbon source, causing the carbon source to encapsulate the catalyst particles and fail. Therefore, by controlling the distance from the plasma generation region to the synthesis region where the catalyst particles are formed to be 1cm-10cm, the pyrolysis time of the catalyst particles in the carbon source mixing and connection region can be controlled to be less than 100ms. A smaller pyrolysis time can prevent the catalyst particles from growing and is conducive to the generation of smaller catalyst particles. In this way, a large number of catalyst particles can be prepared, thereby increasing the yield of single-walled carbon nanotubes.

[0080] (3) Introducing carbon source into the carbon source mixing and connection zone allows the carbon source to achieve a certain mixing effect with the catalyst particles here, and achieves a relative mixing effect before entering the synthesis zone for synthesis, so as to achieve uniform contact between carbon source and catalyst, which can improve carbon yield and increase the synthesis efficiency of single-walled carbon nanotubes.

[0081] (4) The above scheme can not only realize the batch preparation of single-walled carbon nanotubes and improve the yield, but also produce single-walled carbon nanotubes with high yield, good quality and high G / D ratio.

[0082] Please refer to Figure 2 , Figure 2 A flowchart of a method for preparing single-walled carbon nanotubes provided in this application embodiment, the method may include: using the apparatus for preparing single-walled carbon nanotubes as described above, including:

[0083] S101: The first gas is introduced between the cathode and the first anode to generate the first plasma, and then introduced between the first anode and the second anode to generate the second plasma; the temperature of the second plasma is greater than the temperature of the first plasma.

[0084] It should be noted that the specific structure and parameters of the apparatus used in this embodiment for preparing single-walled carbon nanotubes can be referred to in the above embodiments, and will not be repeated here.

[0085] This embodiment does not limit the specific type of the first gas, as long as it can generate plasma. For example, the first gas may include argon. This embodiment does not limit the specific flow rate of the first gas. For example, the flow rate of the first gas can be 2L / min-100L / min, including both values.

[0086] It should be noted that in this embodiment, the cathode, the first anode, and the second anode need to be electrically connected to the plasma power supply. This embodiment does not limit the specific power of the plasma power supply; for example, the power of the plasma power supply electrically connected to the cathode, the first anode, and the second anode can be 1KW-500KW, including the values ​​at both ends.

[0087] S102: The catalyst is introduced between the first anode and the second anode, and after the catalyst forms catalyst particles under the action of the second plasma, it is introduced into the carbon source mixing and connection zone; the pyrolysis time of the catalyst particles in the carbon source mixing and connection zone is less than 100ms.

[0088] It should be noted that the catalyst in this embodiment can be an organic catalyst or an inorganic catalyst. This embodiment does not limit the specific type of catalyst; for example, the catalyst may include ferrocene, cobalt celestene, nickel celestene, ethylferrocene, ferric nitrate, nickel nitrate, cobalt nitrate, ferric acetate, nickel acetate, or cobalt acetate. This embodiment does not limit the specific form of the catalyst; for example, the catalyst may be in powder or liquid form.

[0089] This embodiment does not limit the specific amount of catalyst to be fed. For example, the amount of catalyst to be fed can be 1g / h-300g / h, including the values ​​at both ends.

[0090] It should be noted that the shorter the pyrolysis time of the catalyst particles in the carbon source mixing and connection region, the more favorable it is for generating smaller catalyst particles. In this embodiment, by controlling the distance between the plasma generation region and the synthesis region, the pyrolysis time of the catalyst particles in the carbon source mixing and connection region is controlled to be less than 100 ms, so that the size of the catalyst particles introduced into the synthesis region can be 1 nm-10 nm, including the values ​​at both ends. Preferably, the size of the catalyst particles introduced into the synthesis region can be 1 nm-3 nm, including the values ​​at both ends.

[0091] S103: A carbon source is introduced into the carbon source mixing and connection zone, so that the carbon source and catalyst particles are mixed and then introduced into the synthesis zone to synthesize single-walled carbon nanotubes.

[0092] This embodiment does not limit the specific method of introducing the carbon source into the carbon source mixing and connection zone. For example, the mixture of the promoter and the carbon source can be preheated before being introduced into the carbon source mixing and connection zone; or, the promoter and the carbon source can be preheated separately before being introduced into the carbon source mixing and connection zone. It should be noted that in the former case, the promoter and the carbon source are fed together; in the latter case, the promoter and the carbon source are fed separately through the carbon source inlet. In this embodiment, the preheated mixture of the promoter and the carbon source is introduced into the carbon source mixing and connection zone, and after mixing in the carbon source mixing and connection zone, it is introduced into the synthesis zone. Here, the promoter can further refine the size of the catalyst particles and increase the yield of single-walled carbon nanotubes; preheating can reduce the impact on the temperature field of the synthesis zone.

[0093] This embodiment does not limit the specific type of carbon source. For example, the carbon source may include one or more of ethanol, methane, ethylene, acetylene, benzene, and xylene. This embodiment does not limit the specific feed rate of the carbon source. For example, the feed rate of the carbon source may be 5 mL / h to 1000 mL / h, including both values.

[0094] It should be noted that the accelerator in this embodiment may contain substances such as sulfur, selenium, or phosphorus. This embodiment does not limit the specific type of accelerator; for example, the accelerator may include thiophene, carbon disulfide, sulfur, phosphoric acid, selenophene, iron sulfide, nickel sulfide, or cobalt sulfide. This embodiment does not limit the specific feed rate of the accelerator; for example, the feed rate of the accelerator may be 1 g / h to 200 g / h, including both ends of the range.

[0095] Furthermore, this embodiment may also include: preheating the second gas before introducing it into the carbon source mixing and bonding region. It should be noted that introducing the preheated second gas into the carbon source mixing and bonding region, mixing it in the carbon source mixing and bonding region, and then introducing it into the synthesis region can reduce the impact on the temperature field of the synthesis region.

[0096] This embodiment does not limit the specific type of the second gas, as long as it can be used as a carrier gas. For example, the second gas may include hydrogen. This embodiment does not limit the specific flow rate of the second gas. For example, the flow rate of the second gas can be 2L / min-500L / min, including both values.

[0097] This embodiment does not limit the specific temperature of the synthesis zone. For example, the temperature within the synthesis zone may be 1100℃-1500℃, including both extreme values. It should be noted that the temperature of the synthesis zone in this embodiment can specifically refer to the temperature inside the synthesis furnace.

[0098] Furthermore, after step S103, this embodiment may also include: collecting the single-walled carbon nanotubes that have entered the collection chamber using a receiving shaft.

[0099] Based on the above embodiments, the apparatus for preparing single-walled carbon nanotubes described above is used in this application and also has the above-mentioned beneficial effects.

[0100] The process of preparing single-walled carbon nanotubes described above is illustrated below with specific examples.

[0101] Example 1

[0102] This embodiment adopts Figure 1 The apparatus shown is for preparing single-walled carbon nanotubes. The specific process for preparing single-walled carbon nanotubes using this apparatus is as follows:

[0103] The plasma power supply is started and a first gas (argon is optional) is introduced; the voltage and current of the plasma power supply are controlled to achieve a certain power output, thereby realizing the plasma ignition of argon; the feed amount of catalyst (ferrocene optional) is controlled by a third flow control device (precision powder feeder optional), and the feed amount of carbon source (ethanol optional) and promoter (thiophene optional) is controlled by a first flow control device 81 (precision injection pump optional), and the feed amount of second gas (hydrogen optional) is controlled by a second flow control device 82 (gas proton flow meter optional). Single-walled carbon nanotubes are synthesized in the synthesis furnace 12 and collected in the collection chamber 131.

[0104] The plasma power supply was controlled at 120V and 250A, achieving a power of 30kW. Argon was used as the main gas, with a flow rate of 50L / min to achieve plasmaification. Ferrocene catalyst was fed through catalyst feed line 6 at a rate of 5g / h under the control of a precision powder feeder. Hydrogen was used as the carrier gas, preheated and introduced through second gas inlet line 11 under the control of a proton flow meter, with a flow rate of 30L / min. Thiophene promoter was fed at a rate of 2g / h under the control of a precision injection pump, and ethanol carbon source was fed at a rate of 200mL / h under the control of a precision injection pump. The relevant conditions and parameters are as follows:

[0105] The synthesis temperature inside the synthesis furnace 12 is 1450℃. When feeding each material, a precision injection pump is used to control the material feeding rate at 200mL / h, as shown in Table 1.

[0106] After the reaction, the single-walled carbon nanotubes are collected through the collection chamber 131 and the receiving shaft 132, and the collected product is 30 g / h.

[0107] The generated single-walled carbon nanotube powder was observed using SEM (Scanning Electron Microscope) to obtain... Figure 3 The SEM image shown can be used to characterize the length of the product.

[0108] The generated single-walled carbon nanotube powder was observed using TEM (Transmission Electron Microscope) to obtain... Figure 4 The TEM image shown can be used to characterize the diameter of the product.

[0109] The specific surface area of ​​the generated single-walled carbon nanotube powder can be obtained by performing nitrogen adsorption tests.

[0110] Raman spectroscopy was performed on the generated single-walled carbon nanotube powder to obtain... Figure 5 The Raman spectrum shown is located at 1360 cm⁻¹. -1 and 1550 cm -1 The peaks are D peak and G peak, respectively. D peak represents the non-graphitized structure, and G peak represents the degree of graphitized crystallization. The intensity ratio of G peak and D peak in Raman spectrum IG / ID can characterize the degree of defect in the product.

[0111] Thermogravimetric analysis (TGA) was performed on the generated single-walled carbon nanotube powder to obtain... Figure 6 The TG (thermogravimetric) curve and DTG (differential thermogravimetric) curve shown can be used to obtain the ash content of the test material.

[0112] Examples 2-5

[0113] Using the apparatus and method provided in Example 1, the differences are shown in Table 1 below; single-walled carbon nanotube products were prepared, and the characterization results are shown in Table 1.

[0114] Table 1. Conditions and parameters for each embodiment, and product characterization results.

[0115]

[0116] In summary, the apparatus and method for large-scale preparation of single-walled carbon nanotubes provided by this invention realize the batch preparation of single-walled carbon nanotubes, and the prepared single-walled carbon nanotubes have high yield, good quality and high G / D ratio.

[0117] This document uses specific examples to illustrate the principles and implementation methods of this application. The various embodiments are progressive, with each embodiment focusing on its differences from others. Similar or identical parts between embodiments can be referred to interchangeably. The descriptions of the embodiments above are merely illustrative of the method and core ideas of this application. For those skilled in the art, various improvements and modifications can be made to this application without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of this application.

[0118] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

Claims

1. An apparatus for preparing single-walled carbon nanotubes, characterized in that, include: The plasma generation region, carbon source mixing and connection region, and synthesis region are connected sequentially. The plasma generation zone includes a cathode, a first insulating layer, a first anode, a second insulating layer, and a second anode arranged sequentially; a first gas inlet pipe is provided between the cathode and the first anode; and a catalyst feed pipe is provided between the first anode and the second anode. The distance between the end of the carbon source mixing and connection region that connects to the plasma generation region and the end of the carbon source mixing and connection region that connects to the synthesis region is 1cm-10cm, including the values ​​at both ends; the carbon source mixing and connection region is provided with a carbon source inlet.

2. The apparatus for preparing single-walled carbon nanotubes according to claim 1, characterized in that, A first through hole is provided in the first insulating layer; The first anode has a groove on the side facing the cathode; one end of the cathode is inserted into the groove through the first through hole; a second through hole is provided at the bottom of the groove; the first gas inlet pipe passes through the side wall of the groove and extends into the groove.

3. The apparatus for preparing single-walled carbon nanotubes according to claim 2, characterized in that, The second insulating layer is provided with a third through hole; the catalyst feed pipe passes through the side wall of the third through hole and extends into the interior of the third through hole; The diameter of the second anode is larger than the diameter of the projection of the first anode onto the second anode; a fourth through hole is provided in the second anode; the second through hole, the third through hole, the fourth through hole and the carbon source mixing and connection region are connected in sequence.

4. The apparatus for preparing single-walled carbon nanotubes according to claim 1, characterized in that, The plasma generating region further includes a connector; one end of the connector is connected to the cathode, and the other end is connected to the second anode; the cathode, the connector, and the second anode enclose a cavity; the first insulating layer, the first anode, and the second insulating layer are located within the cavity.

5. The apparatus for preparing single-walled carbon nanotubes according to claim 1, characterized in that, The carbon source inlet and the carbon source feed pipeline are connected; the carbon source feed pipeline includes a first preheater and a first flow control device arranged sequentially in a direction away from the carbon source mixing and connection area.

6. The apparatus for preparing single-walled carbon nanotubes according to claim 1, characterized in that, The carbon source mixing and connection region is provided with a second gas inlet; The second gas inlet is connected to the second gas inlet pipeline; the second gas inlet pipeline includes a second preheater and a second flow control device arranged sequentially in a direction away from the carbon source mixing and connection area.

7. The apparatus for preparing single-walled carbon nanotubes according to claim 1, characterized in that, Also includes: A collection area; the collection area includes a collection bin and a receiving shaft; the collection bin is connected to the synthesis area; one end of the receiving shaft is inserted into the collection bin.

8. The apparatus for preparing single-walled carbon nanotubes according to any one of claims 1 to 7, characterized in that, The diameter of the carbon source mixing and connection region is smaller than the diameter of the synthesis region.

9. The apparatus for preparing single-walled carbon nanotubes according to claim 8, characterized in that, The diameter of the synthesis zone is 5cm-50cm, including the values ​​at both ends.

10. A method for preparing single-walled carbon nanotubes, characterized in that, The apparatus for preparing single-walled carbon nanotubes according to any one of claims 1 to 9 comprises: A first gas is introduced between the cathode and the first anode to generate a first plasma. Then, the gas is introduced between the first anode and the second anode to generate a second plasma. The temperature of the second plasma is higher than that of the first plasma. The catalyst is introduced between the first anode and the second anode, and after the catalyst forms catalyst particles under the action of the second plasma, it is introduced into the carbon source mixing and connection region; the pyrolysis time of the catalyst particles in the carbon source mixing and connection region is less than 100ms. A carbon source is introduced into the carbon source mixing and connection region, and the carbon source is mixed with the catalyst particles and then introduced into the synthesis region to synthesize the single-walled carbon nanotubes.

11. The method for preparing single-walled carbon nanotubes according to claim 10, characterized in that, The step of introducing a carbon source into the carbon source mixing and bonding region includes: The mixture of the accelerator and the carbon source is preheated and then introduced into the carbon source mixing and bonding region; Alternatively, the promoter and the carbon source can be preheated separately and then introduced into the carbon source mixing and bonding region.

12. The method for preparing single-walled carbon nanotubes according to claim 10, characterized in that, Also includes: The second gas is preheated and then introduced into the carbon source mixing and connection region.

13. The method for preparing single-walled carbon nanotubes according to any one of claims 10 to 12, characterized in that, The catalyst particles introduced into the synthesis zone have a size of 1 nm to 10 nm, including the values ​​at both ends.

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