Reactor system
The segmented reactor system solved the problem of catalyst sticking to the wall during carbon nanotube preparation, achieving uniform catalyst distribution and continuous production, improving production efficiency and product quality, and reducing energy consumption and costs.
Patent Information
- Application Number
- CN202520131244.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-20
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2035-01-20
AI Technical Summary
In existing reactors for preparing carbon nanotubes, the catalyst tends to stick to the walls, resulting in short operating cycles, high operational complexity, increased costs, equipment aging, increased safety risks, and energy waste.
A segmented reactor system is adopted, including a moving bed reactor and a fluidized bed reactor. The moving bed reactor carries the initial catalyst to carry out the catalytic reaction, forming a seed catalyst with partial carbon nanotubes. The catalyst is isolated from the reactor wall to prevent adhesion, and electrostatic adsorption is prevented in the fluidized bed, so as to achieve uniform distribution of catalyst and continuous production.
It improves the uniformity and stability of carbon nanotube growth, simplifies the process, reduces energy consumption, extends the continuous production cycle of the fluidized bed reactor, improves production efficiency and material utilization, and reduces production costs.
Smart Images
Figure CN223887980U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of carbon nanotubes, and more specifically, to a reactor system. Background Technology
[0002] The current main method for preparing carbon nanotubes is to use catalysts in fixed-bed or fluidized-bed reactors for catalytic cracking reactions.
[0003] However, catalysts tend to stick to the reactor walls, which significantly reduces operating cycles, increases operational complexity and costs, exacerbates equipment aging and safety risks, and causes unnecessary energy waste.
[0004] Therefore, developing a reactor system that reduces initial catalyst adhesion to the reactor wall, thereby reducing and effectively controlling the agglomeration phenomenon on the reactor wall and greatly improving the reactor operating cycle, is an urgent problem to be solved in this field. Utility Model Content
[0005] This invention aims to address, to a certain extent, one of the technical problems in related technologies. To this end, this application provides a reactor system.
[0006] To achieve the above objectives, as a first aspect of this application, a reactor system for growing carbon nanotubes is disclosed, the reactor system comprising, in sequence:
[0007] At least one moving bed reactor, the moving bed reactor comprising at least one reaction boat and a first reaction body, the first reaction body having a first reaction chamber, the first reaction chamber being capable of accommodating at least one of the reaction boats, the reaction boats being used to carry an initial catalyst, and the reaction boats being capable of entering the first reaction chamber;
[0008] A fluidized bed reactor, the fluidized bed reactor including an intermediate feed inlet, the fluidized bed reactor having a second reaction chamber, the seed catalyst generated by the moving bed reactor being fed into the second reaction chamber through the intermediate feed inlet.
[0009] Furthermore, the moving bed reactor includes a plurality of reaction boats, which are arranged sequentially within the first reaction chamber, and adjacent reaction boats are detachably connected.
[0010] Furthermore, hooks are provided at both ends of the reaction boat along the length of the first reaction chamber, so that adjacent reaction boats can be connected by the hooks.
[0011] Furthermore, the moving bed reactor includes a first discharge device and a first collection device arranged sequentially along the moving direction of the reaction boat. The first discharge device includes a discharge chamber for accommodating the reaction boat carrying the initial catalyst. The first collection device includes a collection chamber for accommodating the reaction boat and collecting the seed catalyst.
[0012] The first reaction chamber includes a feed end and a discharge end, the feed end being connected to the discharge chamber and the discharge end being connected to the receiving chamber.
[0013] Furthermore, the moving bed reactor includes a first discharge device and a first collection device arranged sequentially along the moving direction of the reaction boat. The first discharge device includes a discharge chamber for accommodating the reaction boat carrying the initial catalyst. The first collection device includes a collection chamber for accommodating the reaction boat and collecting the seed catalyst.
[0014] The first reaction body is disposed between the first feeding device and the first receiving device. The first reaction body includes an initial feed port and an initial discharge port that are disposed opposite to each other along the length direction. The initial feed port is connected to the feeding chamber, and the initial discharge port is connected to the receiving chamber.
[0015] Furthermore, the reactor system includes a plurality of moving bed reactors, which are interconnected, such that the first receiving device of the moving bed reactor is adjacent to and connected to the first discharging device of the adjacent moving bed reactor, and the first receiving device of the moving bed reactor is adjacent to and connected to the first receiving device of the adjacent moving bed reactor.
[0016] Furthermore, the reactor system also includes a first transition chamber and a second transition chamber. The first transition chamber is disposed on the side opposite to the first receiving device and / or the first discharging device, and is connected to the receiving chamber or the discharging chamber. The second transition chamber is disposed between adjacent moving bed reactors and connects the discharging chamber of the adjacent moving bed reactor to the receiving chamber.
[0017] Furthermore, the moving bed reactor also includes a first inlet pipe and a first outlet pipe arranged opposite to each other along the length of the first reaction body. One end of the first inlet pipe and the first outlet pipe is inserted into the first reaction body and communicates with the first reaction chamber, so that the gas released from the first inlet pipe is discharged from the first outlet pipe through the first reaction chamber, and the gas flow direction is opposite to the movement direction of the reaction boat in the first reaction chamber.
[0018] Furthermore, the fluidized bed reactor also includes a main discharge port and a reaction gas inlet, the second reaction chamber is connected to the intermediate feed port and the main discharge port, and the reaction gas inlet is located at the bottom of the second reaction chamber and is connected to the second reaction chamber.
[0019] Furthermore, the reaction boat includes one of a quartz boat, a ceramic boat, a silicon carbide boat, and a stainless steel boat.
[0020] This application provides a reactor system for growing carbon nanotubes. By setting up a segmented design of a moving bed reactor and a fluidized bed reactor, the catalyst seed preparation and carbon nanotube growth processes are separated, so that the catalyst contains some carbon nanotubes. This prevents electrostatic adsorption on the reaction wall in the fluidized bed, thereby effectively suppressing the problem of reactor wall agglomeration during fluidized bed production. This segmented multi-reactor system has the following beneficial effects:
[0021] First, the moving bed reactor uses a reaction boat to carry the initial catalyst for catalytic reaction. The reaction boat effectively isolates the initial catalyst from the wall of the first reaction chamber, thus avoiding the adhesion of the initial catalyst within the moving bed reactor. Furthermore, the reaction boat ensures uniform distribution of the catalyst, thereby improving the uniformity of the reaction and promoting the uniform growth of carbon nanotubes on the initial catalyst. This results in a uniform seed catalyst with carbon nanotubes of a specific length. This means that before entering the fluidized bed reactor, the catalyst surface already has a preliminary carbon nanotube structure, providing a more stable starting point for subsequent growth and further improving the anti-adsorption effect on the reactor wall within the fluidized bed reactor.
[0022] The reactor system is designed to allow for continuous catalyst and carbon nanotube preparation, reducing the time consumed by intermediate steps. The seed catalyst in the moving bed reactor can be continuously and uninterruptedly produced, then transferred to the fluidized bed reactor for further carbon nanotube growth, achieving continuous production, simplifying the process, and improving production efficiency. Furthermore, because the seed catalyst has undergone appropriate pretreatment in the first step, the fluidized bed reactor can start up rapidly at a lower temperature and reach a stable operating state. This not only shortens the overall production cycle but also reduces energy consumption.
[0023] The reactor system of this application enables moving bed reactors and fluidized bed reactors to independently control reaction conditions (such as temperature, pressure, gas flow rate, etc.), making the system more flexible and allowing for fine-tuning to meet the process requirements or specific needs at different stages, thereby improving reaction efficiency and reducing the impact of possible side reactions.
[0024] In summary, this technical solution, through a rationally designed multi-stage reactor system, provides reliable technical support for the efficient and high-quality growth of carbon nanotubes, demonstrating significant application value and economic benefits. By optimizing the reactor system structure and process flow, the continuous production capacity of the reactor is significantly improved, production efficiency is greatly increased, the continuity and stability of the fluidized bed production process are ensured, product uniformity and quality stability are enhanced, material utilization is further improved, and energy consumption and raw material loss are reduced, thereby lowering the production cost of carbon nanotubes.
[0025] These features and advantages of this application will be disclosed in detail in the following specific embodiments and accompanying drawings. The best embodiments or means of this application will be shown in detail in conjunction with the accompanying drawings, but are not intended to limit the technical solutions of this application. In addition, each of these features, elements and components appearing in the following text and drawings is multiple and is labeled with different symbols or numbers for convenience, but all represent parts with the same or similar structure or function. Attached Figure Description
[0026] The following description, in conjunction with the accompanying drawings, further illustrates this application:
[0027] Figure 1 A schematic diagram of one embodiment of the reactor system provided in this application;
[0028] Figure 2 This is a schematic diagram of one embodiment of catalyst-grown carbon nanotubes in a conventional reactor.
[0029] Figure 3 A schematic diagram of one embodiment of the moving bed reactor provided in this application;
[0030] Figure 4 A schematic diagram of one embodiment of the seed catalyst provided in this application;
[0031] Figure 5 This is a scanning electron microscope image of carbon nanotubes prepared by the catalyst in Example 1 of this application;
[0032] Figure 6 This is a scanning electron microscope image of carbon nanotubes prepared by the catalyst of Comparative Example 1 of this application.
[0033] Explanation of reference numerals in the attached figures
[0034] 1: Moving bed reactor; 2: Fluidized bed reactor;
[0035] 11a: First feeding device; 11b: First receiving device;
[0036] 12: Reactor boat; 13a: First air inlet pipe; 13b: First air outlet pipe; 14b: Second transition chamber;
[0037] 15: First reaction body; 151: First reaction chamber;
[0038] 21a: Intermediate feed inlet; 21b: Main discharge outlet; 22: Second reaction chamber; 23: Reactant gas inlet;
[0039] 3a: Initial catalyst; 3b: Seed catalyst; 3c: Carbon nanotubes; 3b1: Catalytic metal particles; 3b2: Support particles; 3b3: Sub-carbon nanotubes;
[0040] 21c: Separation outlet; 22a: First fluidized bed reactor; 22b: Second fluidized bed reactor;
[0041] 24: Connecting pipes Detailed Implementation
[0042] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described are intended to explain this application and should not be construed as limiting it.
[0043] The terms "an embodiment," "example," or "example" used in this specification refer to a particular feature, structure, or characteristic described in connection with the embodiment itself that may be included in at least one embodiment disclosed in this application. The phrase "in an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.
[0044] Carbon nanotubes, as a one-dimensional nanomaterial with unique structure and excellent properties, have always been a focus of research and industry in terms of mass production technology. Chemical vapor deposition (CVD) is one of the most widely used and mature technologies for mass production of carbon nanotubes. This method reacts carbon-containing gas with metal nanoparticle catalysts at high temperatures to produce high-quality, high-purity carbon nanotubes in large quantities, making it suitable for industrial production. Reactor designs for mass production of carbon nanotubes vary, but are generally based on the principle of providing high temperatures and uniform gas flow. Fluidized bed technology provides a uniform mass and heat transfer environment for the reaction. In a fluidized bed reactor, catalyst particles are fluidized by an inert gas, which not only greatly increases the contact area between the catalyst particles and the carbon-containing gas but also promotes heat and mass transfer between the gas and the catalyst, making the reaction process more efficient and controllable. Therefore, the fluidized bed reactor combines the advantages of fluidized bed technology with the principles of CVD, achieving efficient and large-scale production of carbon nanotubes. Furthermore, fluidized bed reactors also offer advantages such as flexible operation and ease of continuous production. By adjusting parameters such as gas flow rate, reaction temperature, catalyst type and concentration, the growth process of carbon nanotubes can be precisely controlled, thereby producing carbon nanotube products with different morphologies, structures and properties.
[0045] However, the inventors of this application have discovered that during the operation of a fluidized bed reactor, due to the combined effects of various factors such as electrostatics, fluidization conditions, and changes in catalyst activity, agglomeration and flaking inevitably occur on the reactor wall. Once these wall deposits form and accumulate, they can cause temperature runaway, leading to a rapid increase in the internal temperature of the reactor, which significantly affects the activity of the catalyst and may even cause its performance to deteriorate or become completely ineffective. This series of chain reactions ultimately forces production to stop, severely hindering the continuity and stability of production. Therefore, reducing and effectively controlling agglomeration and flaking on the reactor wall has become a core task for ensuring continuous and efficient production.
[0046] The inventors of this application further discovered that pure catalyst powder adheres more easily to the reactor wall than catalysts with grown carbon nanotubes, leading to increased agglomeration and flaking. To address this problem, the "seed method" process was developed, such as... Figure 2 The diagram shows a flowchart of one embodiment of a method for preparing carbon nanotubes using a conventional reactor. The key to this process is that the initial catalyst 3a is first introduced into the first fluidized bed reactor 22a through the central feed inlet 21a. Reaction gas is introduced into the first fluidized bed reactor 22a from the bottom. The introduced gas fluidizes and reacts the initial catalyst 3a. A certain amount of carbon nanotubes initially grows on the catalyst in the first fluidized bed reactor 22a. Subsequently, the reactants are separated from the gas through the separation outlet 21c, and the catalyst with grown carbon nanotubes is separated as a seed catalyst. Figure 4The diagram shows a schematic representation of one embodiment of the seed catalyst 3b. The seed catalyst 3b comprises a catalytic metal particle 3b1 supported by a carrier particle 3b2, on which carbon nanotubes 3b3 are grown. Subsequently, the seed catalyst 3b is transferred to the second fluidized bed reactor 22b via a connecting pipe 24, where it continues to be fluidized and reacts with the reaction gas. Finally, the desired carbon nanotubes are separated from the main outlet 21b of the second fluidized bed reactor 22b. The introduction of the seed catalyst 3b significantly reduces adsorption and adhesion with the second fluidized bed reactor 22b, enabling the second fluidized bed reactor 22b to achieve longer-term continuous production, significantly extending the production cycle and reducing downtime. However, the first fluidized bed reactor 22a still faces significant challenges. Due to the intense frictional interaction between the initial catalyst and the walls of the first fluidized bed reactor 22a, frequent agglomeration occurs. The first fluidized bed reactor 22a typically requires shutdown for cleaning after no more than one week of operation. This not only increases operational complexity and cost but also exacerbates equipment aging and safety risks, while also causing unnecessary energy waste.
[0047] To address the prominent problems of reactor wall adhesion, agglomeration, and limited production efficiency encountered by current fluidized bed reactors in the continuous production of carbon nanotubes, the inventors of this application have developed a reactor system that enables the continuous production of carbon nanotubes in a fluidized bed reactor using this catalyst, without the problem of reactor wall adhesion, thus overcoming the aforementioned problems and defects.
[0048] To achieve the above objectives, as a first aspect of this application, a reactor system is disclosed, such as Figure 1 As shown, the reactor system is used to grow carbon nanotubes 3c, and the reactor system includes the following components arranged in sequence:
[0049] At least one moving bed reactor 1, the moving bed reactor 1 including at least one reaction boat 12 and a first reaction body 15, the first reaction body 15 having a first reaction chamber 151, the first reaction chamber 151 being able to accommodate at least one reaction boat 12, the reaction boat 12 being used to carry the initial catalyst 3a, and the reaction boat 12 being able to enter the first reaction chamber 151;
[0050] The fluidized bed reactor 2 includes an intermediate feed inlet 21a and a second reaction chamber 22. The seed catalyst 3b produced by the moving bed reactor 1 can be fed into the second reaction chamber 22 through the intermediate feed inlet 21a.
[0051] This application provides a reactor system for growing carbon nanotubes. By setting up a segmented design of a moving bed reactor 1 and a fluidized bed reactor 2, the preparation of seed catalyst 3b and the growth process of carbon nanotubes 3c are separated. This allows the catalyst to contain some carbon nanotubes, preventing electrostatic adsorption onto the reaction wall within the fluidized bed, thereby effectively suppressing the problem of reactor wall agglomeration during fluidized bed production. This segmented multi-reactor system has the following beneficial effects:
[0052] First, the moving bed reactor 1 carries the initial catalyst 3a for catalytic reaction via a reaction boat 12. The reaction boat 12 effectively isolates the initial catalyst 3a from the wall of the first reaction chamber 151, thereby preventing the initial catalyst 3a from sticking together in the moving bed reactor 1. The reaction boat 12 also ensures uniform distribution of the catalyst, thereby improving the uniformity of the reaction and promoting the uniform growth of carbon nanotubes on the initial catalyst 3a, forming a uniform seed catalyst 3b with carbon nanotubes of a specific length. This means that before entering the fluidized bed reactor 2, the catalyst surface already has a preliminary carbon nanotube structure, providing a more stable starting point for subsequent growth and further improving the anti-adsorption effect on the wall of the fluidized bed reactor 2.
[0053] The reactor system is designed to allow for continuous preparation of the catalyst and carbon nanotubes, reducing the time consumed by intermediate steps. The seed catalyst 3b in the moving bed reactor 1 can be continuously and uninterruptedly produced, and then transferred to the fluidized bed reactor 2 to continue growing carbon nanotubes 3c, achieving continuous production, simplifying the process flow, and improving production efficiency. Furthermore, since the seed catalyst 3b has already undergone appropriate pretreatment in the first step, the fluidized bed reactor 2 can start up rapidly at a lower temperature and reach a stable operating state. This not only shortens the overall production cycle but also reduces energy consumption.
[0054] The reactor system described in this application allows for independent control of reaction conditions (such as temperature, pressure, and gas flow rate) between the moving bed reactor 1 and the fluidized bed reactor 2. This makes the system more flexible, enabling precise control for different stages of the process or specific needs, improving reaction efficiency and reducing potential side reactions. This technical solution, through a rationally designed multi-stage reactor system, provides reliable technical support for the efficient and high-quality growth of carbon nanotubes, demonstrating significant application value and economic benefits. By optimizing the reactor system structure and process flow, the continuous production capacity of the reactor is significantly improved, greatly increasing production efficiency, ensuring the continuity and stability of the fluidized bed production process, enhancing product uniformity and quality stability, further improving material utilization, and reducing energy consumption and raw material loss, thereby lowering the production cost of carbon nanotubes.
[0055] To facilitate understanding, the principles of preventing wall adhesion for conventional catalysts and seed catalysts will be explained below. Conventional catalyst support particles typically use insulating polar materials. This causes a shift in the center of gravity of the positive and negative charges within the support particles. Furthermore, due to insulation, the transfer of positive and negative charges within the support particles is impossible, resulting in a tendency for like poles to repel and unlike poles to attract between the inherent dipoles within the support particles. This causes the support particles to tend to approach the electrostatically charged reactor wall, forming what is known as electrostatic adsorption. Once the support particles are adsorbed onto the reactor wall, the reactant gas reacts with the catalytic metal particles on the support particles, growing carbon nanotubes. As the number of carbon nanotubes accumulates, the problem of wall adhesion occurs. Conversely, the structure of seed catalyst 3b is as follows... Figure 4 As shown, the catalyst supports have carbon nanotubes growing on their surface, forming a catalyst structure with carbon nanotube coating. Carbon nanotubes are non-polar conductive materials. Non-polar materials generally have symmetrical molecular structures with their positive and negative charge centers coinciding. Due to their conductivity, positive and negative charges can be rapidly transferred and neutralized. Since their positive and negative charge centers always coincide, they prevent the generation of an internal electric field and are therefore not adsorbed by external electrostatics. In other words, they are not adsorbed by the walls of the electrostatically charged fluidized bed reactor 2. Thus, the seed catalyst 3b can directly avoid adsorption on the reactor wall and causing adhesion.
[0056] This application does not impose a specific limit on the number of reaction boats 12. However, to enable the moving bed reactor 1 to continuously produce seed catalyst 3b and improve production efficiency, it is preferable that the moving bed reactor 1 includes multiple reaction boats 12, such as... Figure 1 As shown, multiple reaction boats 12 are arranged sequentially within the first reaction chamber 151, with adjacent reaction boats 12 detachably connected. This arrangement allows multiple reaction boats 12 to carry more initial catalyst 3a to form seed catalyst 3b, thereby increasing the yield of the moving bed reactor 1. Preferably, hooks are provided at both ends of the reaction boats 12 along the length of the first reaction chamber 151, allowing adjacent reaction boats 12 to be connected via the hooks.
[0057] This application does not impose any special limitations on the material of the reaction boat 12, as long as the reaction boat 12 can carry the catalyst and prevent the catalyst from contacting the wall of the first reaction chamber 151. Preferably, the reaction boat 12 includes one of the following: quartz boat, ceramic boat, silicon carbide boat and stainless steel boat. The above-mentioned reaction boat 12 can withstand high temperatures and has stability, and can prevent the catalyst from agglomerating and sticking inside the boat.
[0058] As an optional implementation, the moving bed reactor 1 includes a first discharge device 11a and a first collection device 11b arranged sequentially along the moving direction of the reaction boat 12. The first discharge device 11a includes a discharge chamber for accommodating the reaction boat 12 carrying the initial catalyst 3a. The first collection device 11b includes a collection chamber for accommodating the reaction boat 12 and collecting the seed catalyst 3b. A first reaction body 15 is disposed between the first discharge device 11a and the first collection device 11b. The first reaction body 15 includes an initial inlet and an initial outlet arranged opposite to each other along the length direction. The initial inlet is connected to the discharge chamber, and the initial outlet is connected to the collection chamber. Specifically, a predetermined weight of initial catalyst 3a is weighed in the first discharge device 11a and evenly distributed into the reaction boat 12. After passing through the first reaction chamber 151, the seed catalyst 3b in the reaction boat 12 is collected at the first collection device 11b. In some embodiments, the first discharge device 11a and the first collection device 11b can be vacuum glove boxes to prevent external environment from contaminating the catalyst and the reaction chamber. In addition, the first collection device 11b can immediately transfer the seed catalyst 3b after the catalytic reaction in the first discharge device 11a to the fluidized bed reactor 2, and at the same time put the reaction boat 12 after the reaction back into the first collection device 11b for recycling, thereby improving the production efficiency.
[0059] As an optional implementation, the moving bed reactor 1 also includes a drive unit (not shown), such as... Figure 1 As shown, the driving component is disposed within the discharge chamber. The driving component pushes the reaction boat 12 within the discharge chamber into the first reaction chamber 151. Simultaneously, it causes multiple sequentially connected reaction boats 12 to move along the pushing direction within the first reaction chamber 151, and causes the reaction boat 12 closest to the first receiving device 11b to enter the receiving chamber from the first reaction chamber 151. The driving component can promptly push the boats that have completed the catalytic reaction from the first reaction chamber 151 into the first receiving device 11b, ensuring that the structure of the seed catalyst 3b within the multiple boats is consistent and uniform. Furthermore, it can control the movement of the boats to prevent the catalyst from agglomerating in the first reaction chamber 151 due to prolonged catalytic reaction.
[0060] As an optional implementation, the reactor system includes multiple moving bed reactors 1, which are interconnected. The first receiving device 11b of one moving bed reactor 1 is adjacent to and connected to the first discharging device 11a of the adjacent moving bed reactor 1, and vice versa. This arrangement allows for internal circulation within the moving bed to prepare carbon nanotubes without contact with the external environment, preventing contamination. Alternatively, other methods can be used to prepare carbon nanotubes, such as activating a catalyst in one of the first reaction modules and growing a seed catalyst in an adjacent first reaction module. Alternatively, this reactor system can be used as two independent reaction devices, without interconnection.
[0061] The reactor system also includes a first transition chamber (not shown) and a second transition chamber 14b, such as Figure 3 As shown, the first transition chamber is located on the side opposite to the first receiving device or the first discharging device. The first transition chamber is connected to the receiving chamber or the discharging chamber and is mainly used to store the catalyst and seed catalyst. The second transition chamber 14b is located between adjacent moving bed reactors and connects the discharging chamber and the receiving chamber of the adjacent moving bed reactors. This arrangement allows the reaction boat 12, which has completed the catalytic reaction in the first reaction chamber 151, to first remove the seed catalyst 3b through the first receiving device 11b. Then, the reaction boat 12 is transferred through the second transition chamber 14b to the adjacent first discharging device 11a for recycling. This realizes continuous recycling and production of the moving bed reactor 1, reduces process steps, reduces pollution, and improves production efficiency and product quality.
[0062] The moving bed reactor 1 also includes a first inlet pipe 13a and a first outlet pipe 13b arranged opposite to each other along the length of the first reaction body 15. One end of the first inlet pipe 13a and the first outlet pipe 13b is inserted into the first reaction body 15 and communicates with the first reaction chamber 151, so that the gas released from the first inlet pipe 13a is discharged from the first outlet pipe 13b through the first reaction chamber 151. The gas flow direction is opposite to the movement direction of the reaction boat 12 in the first reaction chamber 151. This allows the gas to fully contact the initial catalyst 3a in the reaction boat 12 to carry out a catalytic reaction, and prevents the catalyst from moving and agglomerating.
[0063] Preferably, the moving bed reactor 1 can also be a pusher furnace.
[0064] Preferably, the wall material of the first reaction chamber 151 includes quartz glass. Quartz glass is an excellent electrical insulator, which provides additional safety protection for the wall of the first reaction chamber 151 in cases involving electrical equipment or where it is necessary to prevent the accumulation of static electricity. It is not prone to potential difference and electrostatic adsorption, thus making it difficult for the catalyst to adhere to the surface of the wall of the first reaction chamber 151. In addition, quartz glass has excellent heat resistance, maintaining its physical and chemical properties unchanged at high temperatures. This is very important for the high-temperature environment required in the growth of carbon nanotubes (such as in the CVD method). Furthermore, due to its low coefficient of thermal expansion, quartz glass generates less thermal stress during heating and cooling, reducing the risk of cracks or breakage caused by temperature changes. Moreover, due to its chemical inertness, quartz glass does not release any impurities or byproducts that may interfere with the reaction process, ensuring the purity of the generated carbon nanotubes 3C.
[0065] As an optional implementation, the fluidized bed reactor 2 includes a main discharge port 21b and a reaction gas inlet 23. The second reaction chamber 22 is connected to the intermediate feed port 21a and the main discharge port 21b. The reaction gas inlet 23 is located at the bottom of the second reaction chamber 22 and is connected to the second reaction chamber 22. This allows the prepared seed catalyst 3b to enter the second reaction chamber 22 through the intermediate feed port 21a, and the reaction gas inlet 23 at the bottom is blown into the reactor, carrying the seed catalyst 3b, and fluidizing the seed catalyst 3b to carry out the catalytic reaction. After the reaction is fully completed, carbon nanotubes 3c are obtained.
[0066] This application does not impose specific limitations on how the seed catalyst prepared in the moving bed reactor is transferred to the feed inlet of the fluidized bed reactor. For example, it can be transferred manually, or it can be transferred using an automated device such as a conveyor belt. As an optional implementation, to avoid environmental contamination of the product seed catalyst during the transfer process, it is preferable to collect the seed catalyst prepared in the moving bed reactor in a first receiving device and load it into a seed tank. The seed tank is a sealed storage vessel that can prevent contamination of the seed catalyst. The seed tank is then weighed to obtain the weight of the seed catalyst relative to the initial catalyst, thereby determining the growth state of the seed catalyst. Preferably, the weight of the seed catalyst is between 500% and 3000% of the weight of the initial catalyst. Seed catalysts within this range can achieve optimal fluidization and full reaction in the fluidized bed reactor, improving catalytic efficiency.
[0067] To facilitate understanding, the following explanation is provided regarding how the reactor system prepares carbon nanotubes 3c: The initial catalyst 3a is placed in the moving bed reactor 1. A predetermined weight of the initial catalyst 3a is weighed in the first discharge device 11a and continuously and uniformly distributed onto the reaction boat 12. Then, the reaction boat 12 is pushed into the first reaction chamber 151 at a predetermined speed by a drive component to carry out the first catalytic reaction, so that the initial catalyst 3a forms a seed catalyst 3b with partial carbon nanotubes. The temperature range of the first reaction chamber 151 is between 660°C and 900°C, and the residence time is between 0.3 hours and 1 hour. At the same time, the reaction boat 12 at the end of the first reaction chamber 151 is pushed out into the first receiving device 11b.
[0068] In the first receiving device 11b, the seed catalyst 3b is transferred to the middle feed port 21a of the fluidized bed reactor 2. The seed catalyst 3b enters the second reaction chamber 22. The flow rates of nitrogen and carbon source gas at the reaction gas inlet 23 at the bottom of the fluidized bed reactor 2 are adjusted. The seed catalyst 3b is fluidized by the reaction gas blown in from the bottom and undergoes a second catalytic reaction. The temperature range of the second reaction chamber 22 is between 680°C and 750°C, and the reaction time is between 0.5 hours and 1.5 hours, so that the seed catalyst 3b grows into carbon nanotubes 3c. The carbon nanotubes 3c are collected from the main discharge port 21b.
[0069] The present application will be further described below with reference to the embodiments.
[0070] Example
[0071] Example 1
[0072] The initial catalyst is placed into the moving bed reactor, wherein a predetermined weight of the initial catalyst (Fe) is weighed in the first discharge device. x Co y O z Al2O3 oxide powder was placed into a reaction boat, and then the reaction boat was pushed into the first reaction chamber by a drive device to carry out the first catalytic reaction. Propylene gas was introduced through the first inlet pipe and reacted with the catalyst, so that the initial catalyst formed a seed catalyst with partial carbon nanotubes. The temperature of the first reaction chamber was 690°C and the residence time was 0.5 hours. The seed catalyst was prepared, and the weight of the seed catalyst accounted for 120% of the weight of the initial catalyst.
[0073] In the first receiving device, the seed catalyst is transferred to the middle feed port of the fluidized bed reactor. The seed catalyst enters the second reaction chamber. A 1:1 mixture of propylene and nitrogen is blown in from the bottom to fluidize the seed catalyst and cause a second catalytic reaction, which allows the seed catalyst to grow into carbon nanotubes. Carbon nanotubes 1 are collected from the discharge port.
[0074] Comparative Example 1
[0075] The initial catalyst was directly fed into the fluidized bed reactor through the middle feed port. A 1:1 mixture of propylene and nitrogen was blown in from the bottom to fluidize the initial catalyst and induce a catalytic reaction, thus preparing carbon nanotubes 2.
[0076] Test case
[0077] The running time of the fluidized bed reactors used in the catalyst preparation of carbon nanotubes in the examples and comparative examples was statistically analyzed. The running time refers to the total running time from the start of normal operation of the fluidized bed reactor to the point where the temperature runaway caused the reactor temperature to become uncontrollable and the reactor was shut down. The results are shown in Table 1.
[0078] Taking advantage of the characteristic of carbon nanotube products undergoing oxidation and weight loss in high-temperature air, 2g of the carbon nanotube products prepared in the examples and comparative examples were weighed out and placed in a MY-X-12 muffle furnace at 850°C for 4 hours in an air atmosphere. The remaining weight after calcination (i.e., the weight of ash) was measured to obtain the ash mass percentage, which satisfies the following formula:
[0079] Ash content (wt%) = (Weight of material before ignition - Remaining weight after ignition) / Weight of material before ignition %
[0080] The purity of carbon nanotube products is obtained by measuring the ash content ratio. The purity of carbon nanotube products is calculated as 1 - ash content ratio. The purity of carbon nanotube products was tested and statistically analyzed using the above purity testing method, and the results are shown in Table 1.
[0081] The microstructure of the carbon nanotubes in Example 1 and Comparative Example 1 was observed using a FEI Inspect F50 scanning electron microscope, and microscopic morphology images of the carbon nanotubes were obtained, as shown below. Figure 5 and Figure 6 As shown, the carbon nanotubes prepared using the reactor system of this application exhibit the same morphological characteristics as those prepared by comparative growth. Both contain multiple irregularly arranged carbon nanotubes with consistent pore sizes, displaying an oriented structure and maintaining their microscopic morphological properties. This demonstrates that the reactor system of this application does not cause contamination during carbon nanotube growth, nor does it affect the morphological structure of the final carbon nanotube product. Furthermore, it significantly improves the operating time of the fluidized bed reactor, increases production efficiency, reduces downtime frequency, and lowers production costs.
[0082] Table 1
[0083]
[0084] As can be seen from the data in Table 1, compared to the comparative example, the seed catalyst in Example 1 enabled the fluidized bed to exhibit a longer continuous operating time and also improved the purity of the prepared carbon nanotube product. This comparison shows that the seed catalyst pre-prepared using the reactor system in this application can effectively suppress the problem of reactor wall agglomeration during fluidized bed production, not only enhancing the continuous production capacity of the fluidized bed reactor but also ensuring higher consistency and stability of the carbon nanotube product purity.
[0085] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.
Claims
1. A reactor system, characterized in that, The reactor system is used to grow carbon nanotubes, and the reactor system comprises, in sequence: At least one moving bed reactor (1), the moving bed reactor comprising at least one reaction boat (12) and a first reaction body (15), the first reaction body having a first reaction chamber (151), the first reaction chamber being capable of accommodating at least one of the reaction boats, the reaction boats being used to carry an initial catalyst, and the reaction boats being capable of entering the first reaction chamber; The fluidized bed reactor (2) includes an intermediate feed inlet (21a) and a second reaction chamber (22), through which the seed catalyst generated by the moving bed reactor can be fed into the second reaction chamber.
2. The reactor system according to claim 1, characterized in that, The moving bed reactor includes a plurality of reaction boats, which are arranged sequentially within the first reaction chamber, and adjacent reaction boats are detachably connected.
3. The reactor system according to claim 2, characterized in that, The reaction boat is provided with hooks at both ends along the length of the first reaction chamber, so that adjacent reaction boats can be connected by the hooks.
4. The reactor system according to claim 1, characterized in that, The moving bed reactor includes a first discharge device (11a) and a first collection device (11b) arranged sequentially along the moving direction of the reaction boat. The first discharge device (11a) includes a discharge chamber for accommodating the reaction boat carrying the initial catalyst. The first collection device includes a collection chamber for accommodating the reaction boat and collecting the seed catalyst. The first reaction body is disposed between the first feeding device and the first receiving device. The first reaction body includes an initial feed port and an initial discharge port that are disposed opposite to each other along the length direction. The initial feed port is connected to the feeding chamber, and the initial discharge port is connected to the receiving chamber.
5. The reactor system according to claim 4, characterized in that, The moving bed reactor includes a drive unit disposed in the discharge chamber. The drive unit is used to push the reaction boat in the discharge chamber into the first reaction chamber, while causing a plurality of reaction boats connected in sequence to move in the first reaction chamber along the pushing direction, and causing the reaction boat near the first receiving device to enter the receiving chamber from the first reaction chamber.
6. The reactor system according to claim 5, characterized in that, The reactor system includes multiple moving bed reactors, which are interconnected, such that the first receiving device of one moving bed reactor is adjacent to and connected to the first discharging device of the adjacent moving bed reactor, and the first receiving device of one moving bed reactor is adjacent to and connected to the first receiving device of the adjacent moving bed reactor.
7. The reactor system according to claim 6, characterized in that, The reactor system further includes a first transition chamber and a second transition chamber. The first transition chamber is disposed on the side opposite to the first receiving device or the first discharging device, and is connected to the receiving chamber or the discharging chamber. The second transition chamber is disposed between adjacent moving bed reactors and connects the discharging chamber of the adjacent moving bed reactor to the receiving chamber.
8. The reactor system according to any one of claims 1 to 7, characterized in that, The moving bed reactor further includes a first inlet pipe (13a) and a first outlet pipe (13b) arranged opposite to each other along the length of the first reaction body. One end of the first inlet pipe and the first outlet pipe is inserted into the first reaction body and communicates with the first reaction chamber, so that the gas released from the first inlet pipe is discharged from the first outlet pipe through the first reaction chamber, and the gas flow direction is opposite to the movement direction of the reaction boat in the first reaction chamber.
9. The reactor system according to any one of claims 1 to 7, characterized in that, The fluidized bed reactor further includes a main discharge port (21b) and a reaction gas inlet (23). The second reaction chamber is connected to the intermediate feed port and the main discharge port. The reaction gas inlet is located at the bottom of the second reaction chamber and is connected to the second reaction chamber.
10. The reactor system according to any one of claims 1 to 7, characterized in that, The reaction boat includes one of the following: quartz boat, ceramic boat, silicon carbide boat, and stainless steel boat.