A continuous single-walled carbon nanotube collection device and method

Abstract

The application discloses a kind of single-wall carbon nanotube continuous collection device and method.The device is used to collect single-wall carbon nanotube into the deposition area of tubular reactor, including collection cavity, negative pressure system and dynamic collection component;Dynamic collection component includes: rotatably arranged in the roller of collection cavity;Perforated collection layer is covered on the outer surface of roller, for adsorbing single-wall carbon nanotube;Drive unit is used to drive roller to rotate around its axis;Scraper is arranged in the collection cavity, for peeling single-wall carbon nanotube attached on the perforated collection layer;Under the action of negative pressure system, gas flow carries single-wall carbon nanotube through the deposition area of tubular reactor into collection cavity, and is adsorbed on the perforated collection layer;Through the contact of roller and scraper, the continuous peeling and collection of single-wall carbon nanotube are realized.

Description

Technical Field

[0001] This invention relates to the field of single-walled carbon nanotube (SWCNT) preparation technology, specifically to a continuous collection device and method for SWCNTs. Background Technology

[0002] Single-walled carbon nanotubes are considered the core of next-generation nanomaterials due to their exceptional electrical, optical, and mechanical properties.

[0003] Floating catalyst chemical vapor deposition (FCCVD) is currently the mainstream method for preparing SWCNTs.

[0004] For example, the patent specification with publication number CN120989584A discloses a chemical vapor deposition reactor, an FCCVD reactor, and a method for the continuous batch preparation of single-walled carbon nanotubes. By optimizing the structure of the reactor, the flow field inside the reactor is optimized to achieve uniform gas distribution, maintain the in-situ growth of catalyst particles and the uniformity of particle size. This not only enables the continuous batch preparation of single-walled carbon nanotubes, but also greatly improves the utilization efficiency of the catalyst, significantly increases the yield per unit catalyst, and produces high-quality SWCNTs.

[0005] For example, patent specification CN116534842A discloses an apparatus and method for continuously preparing and collecting sponge-like single-walled carbon nanotubes using a floating catalyst chemical vapor deposition (VCVD) method. This apparatus includes a micro-injection pump for supplying a catalyst and a liquid carbon source, a floating catalyst VCVD reaction chamber, and a continuous collection and transfer device. The specific structure is as follows: the floating catalyst VCVD reaction chamber is horizontally inserted into the cavity of a tube furnace. A syringe is installed on the micro-injection pump to form a catalyst injection device. The micro-injection pump corresponds to the central hole at the beginning of the floating catalyst VCVD reaction chamber via the syringe. The cross-shaped cylindrical channel of the continuous collection and transfer device is connected to the end of the floating catalyst VCVD reaction chamber. This patented technology overcomes the problem that current floating catalyst VCVD methods cannot achieve continuous collection of sponge-like single-walled carbon nanotubes.

[0006] FCCVD typically faces a core bottleneck: during the reaction process, carbon nanotube aerosols are prone to depositing and accumulating on the inner wall of the high-temperature corundum tube due to Brownian motion, thermophoresis, and van der Waals forces. This results in low raw material utilization, unstable process, and the need to interrupt production for cleaning, making continuous large-scale preparation impossible.

[0007] Existing collection technologies (such as direct filtration, liquid bubbling, etc.) may have problems such as discontinuous collection and easy clogging, or may introduce contamination that damages the purity of the product. Summary of the Invention

[0008] To address the aforementioned technical problems and shortcomings in this field, this invention provides a continuous collection device and method for single-walled carbon nanotubes (SWCNTs). The device design incorporates three key technological concepts: First, a controllable negative pressure is applied at the rear end of the tubular reactor to create directional tension, enhancing airflow and suppressing carbon nanotube diffusion towards the tube wall. Second, a rotating roller covered with a metal mesh is used as the dynamic collection surface, achieving simultaneous continuous adsorption and vacant surface, overcoming the clogging problem of the fixed filter membrane. Finally, a magnetic levitation motor is introduced to drive the roller, achieving contactless, zero-pollution, and low-vibration precision rotation control, ensuring high product purity and stable collection process. This invention fundamentally solves the continuous collection problem in SWCNT preparation, providing an innovative technological path for industrial-scale continuous production.

[0009] The specific technical solution of this invention is as follows: In a first aspect, the present invention provides a continuous collection device for single-walled carbon nanotubes, used to collect single-walled carbon nanotubes entering the deposition zone of a tubular reactor. The continuous collection device for single-walled carbon nanotubes includes a collection chamber, a negative pressure system, and a dynamic collection component. The dynamic collection assembly includes: a roller rotatably disposed within the collection chamber; a porous collection layer covering the outer surface of the roller for adsorbing single-walled carbon nanotubes; a driving unit for driving the roller to rotate around its axis; and a scraper disposed within the collection chamber for peeling off the single-walled carbon nanotubes attached to the porous collection layer. Under the action of the negative pressure system, the airflow carries single-walled carbon nanotubes through the deposition zone of the tubular reactor into the collection chamber, where they are adsorbed onto the porous collection layer.

[0010] The core of this invention lies in the fact that a negative pressure adsorption guiding module (negative pressure system) and a dynamic continuous collection module are sequentially arranged downstream of the gas flow in the tubular reactor, and the two work together.

[0011] The negative pressure adsorption guiding module establishes and maintains a controllable negative pressure environment within the collection chamber connected to the end of the tubular reactor using a vacuum pump, creating a directional airflow pull. This pull effectively inhibits the diffusion of carbon nanotube aerosols to the tube wall due to Brownian motion and other effects, forcing them to concentrate in the predetermined collection area, thereby reducing tube wall deposition at the source.

[0012] The dynamic continuous collection module is key to achieving continuous collection. Its core component is a roller located within the collection chamber and capable of rotating around its own axis. The outer surface of this roller is covered with a metal mesh (porous collection layer) to capture carbon nanotubes. Under negative pressure, the carbon nanotubes are adsorbed onto the surface of the metal mesh. Simultaneously, the roller rotates slowly under the drive unit, and upon contact with the scrapers on the side, the carbon nanotubes on the metal mesh surface are continuously removed, maintaining real-time renewal of the metal mesh surface and thus achieving uninterrupted collection.

[0013] In some preferred embodiments, the single-walled carbon nanotube continuous collection device uses a magnetic levitation motor as its drive unit, ensuring full contact between the carbon nanotubes and the metal mesh under the influence of airflow. This design eliminates lubricant contamination, friction particle contamination, and mechanical vibration that can occur with traditional mechanical bearings, ensuring the purity of the collection environment and the extreme smoothness of the roller rotation. This is crucial for maintaining the high purity of the nanomaterial products and the uniformity of the collection layer.

[0014] In some preferred embodiments, the single-walled carbon nanotube continuous collection device includes a negative pressure system comprising a vacuum pump equipped with a butterfly valve, wherein the negative pressure environment within the collection chamber is stably controlled by adjusting the opening of the butterfly valve.

[0015] In some preferred embodiments, the single-walled carbon nanotube continuous collecting device has a hollow interior and a porous surface on the roller. Further, the roller may be a hollow cylinder. Further, the porous structure has pores with a size of 1-2 cm. The air extraction port of the negative pressure system communicates with the interior of the roller, allowing airflow to be drawn away through the porous collecting layer and the roller.

[0016] In some preferred embodiments, the porous collection layer of the single-walled carbon nanotube continuous collection device is a molybdenum mesh or a tungsten mesh.

[0017] In some preferred embodiments, the single-walled carbon nanotube continuous collection device has a porous collection layer with pores of 1-2 μm in size.

[0018] In some preferred embodiments, in the single-walled carbon nanotube continuous collection device, the tubular reactor deposition zone and the collection chamber are connected by a corrugated pipe. The end of the tubular reactor (deposition zone) is connected to the collection chamber, and the corrugated pipe, as a connecting channel, effectively absorbs and compensates for the deformation of the tubular reactor at high temperatures caused by temperature differences through its axial, lateral, or angular elastic deformation, thus avoiding the risk of tubular reactor rupture due to thermal stress.

[0019] In some preferred embodiments, the single-walled carbon nanotube continuous collection device uses a tubular reactor with a reaction tube made of corundum or silicon carbide.

[0020] In some preferred embodiments, the single-walled carbon nanotube continuous collection device has a negative pressure inside the collection chamber, with a pressure value of 0.04-0.09 MPa.

[0021] In some preferred embodiments, the single-walled carbon nanotube continuous collection device further includes a control unit; The collection chamber is connected to a pressure sensor; The negative pressure system is connected to the control unit; The control unit adjusts the operation of the negative pressure system, the drive unit, and the single-walled carbon nanotube synthesis reaction based on the signal from the pressure sensor. When the pressure inside the tubular reactor and the collection chamber exceeds the set safety value, relevant signals are fed back to the gas and liquid supply systems, and the reaction is immediately stopped, further ensuring safe production.

[0022] In some preferred embodiments, the scraper and roller of the single-walled carbon nanotube continuous collection device are placed parallel to each other in the axial direction.

[0023] In some preferred embodiments, the continuous collection device for single-walled carbon nanotubes has a collection chamber with a viewing window, allowing real-time observation of the generation and collection of single-walled carbon nanotubes.

[0024] In some preferred embodiments, the viewing window of the single-walled carbon nanotube continuous collection device is made of silicon dioxide.

[0025] In a second aspect, the present invention provides a method for continuous collection of single-walled carbon nanotubes, using the continuous collection device for single-walled carbon nanotubes described in the first aspect. The method for continuous collection of single-walled carbon nanotubes includes: The growth of single-walled carbon nanotubes is achieved through a gas-phase reaction within a tubular reactor. The negative pressure system is activated to establish negative pressure in the collection chamber, allowing the airflow carrying single-walled carbon nanotubes to enter the collection chamber. Start the drive unit to rotate the roller covered with the porous collection layer; Single-walled carbon nanotubes are adsorbed onto the surface of the porous collection layer under negative pressure; The continuous peeling and collection of single-walled carbon nanotubes is achieved through the contact between the roller and the scraper.

[0026] This invention can solve the technical problems of production interruption, low collection efficiency, and inability to operate continuously caused by the deposition and aggregation of carbon nanotubes at the end of the tubular reactor wall during the preparation of single-walled carbon nanotubes by floating catalyst chemical vapor deposition.

[0027] Compared with the prior art, the beneficial effects of this invention are as follows: This invention combines negative pressure guidance with dynamic rotational collection, supplemented by pollution-free magnetic levitation drive, to achieve efficient, continuous, and clean physical collection of single-walled carbon nanotubes without interrupting the chemical reaction process or introducing any external contaminants. This invention significantly improves raw material utilization, process stability, and equipment operating cycle, providing a reliable equipment foundation for the industrial-scale continuous production of single-walled carbon nanotubes. Attached Figure Description

[0028] Figure 1This is a schematic diagram of the structure of a continuous collection device for single-walled carbon nanotubes according to the present invention.

[0029] Figure 2 for Figure 1 An optical photograph of single-walled carbon nanotubes collected in the collection chamber of the continuous collection device shown.

[0030] Figure 3 for Figure 1 An optical photograph of the inner wall of the downstream tubular reactor after the single-walled carbon nanotube continuous collection device has been running continuously for 24 hours. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0032] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0033] See Figure 1 A continuous collection device for single-walled carbon nanotubes is disclosed, used to collect single-walled carbon nanotubes entering the deposition zone 2 of a tubular reactor 1. The reaction tube in the tubular reactor 1 is horizontal and made of corundum. A carbon source (such as n-hexane), a catalyst precursor (such as ferrocene), and a carrier gas (such as argon / hydrogen) undergo a chemical vapor deposition reaction in the tubular reactor 1 to generate single-walled carbon nanotube aerosols.

[0034] The continuous collection device for single-walled carbon nanotubes includes a collection chamber 5, a negative pressure system, and a dynamic collection component. The main body of the collection chamber 5 is made of stainless steel and has a viewing window 6, allowing real-time observation of the generation and collection of single-walled carbon nanotubes. The viewing window 6 is made of silicon dioxide. The collection chamber 5 is also connected to a pressure sensor 11.

[0035] The sedimentation zone 2 of the tubular reactor 1 is connected to the collection chamber 5 via a flange 3 and a bellows 4. The bellows 4 serves as a connecting channel, effectively absorbing and compensating for the deformation of the tubular reactor 1 at high temperatures caused by temperature differences through its axial, lateral, or angular elastic deformation. This compensates for the thermal expansion difference between the high temperature of the reaction zone and the low temperature of the collection zone, avoiding the risk of the tubular reactor 1 rupturing due to thermal stress, and also facilitating installation and alignment.

[0036] The dynamic collection assembly includes: a roller 8 rotatably disposed within a collection chamber 5; a porous collection layer 10 covering the outer surface of the roller 8 for adsorbing single-walled carbon nanotubes; a driving unit 7 for driving the roller 8 to rotate around its axis; and a scraper 9 disposed within the collection chamber 5 for peeling off the single-walled carbon nanotubes attached to the porous collection layer 10. The scraper 9 is placed parallel to the axial direction of the roller 8. The roller 8 contacts the scraper 9 on its side, and as the roller 8 rotates, the products on its surface porous collection layer 10 are continuously removed, maintaining the real-time renewal of the porous collection layer 10.

[0037] The roller 8 is made of metal and is rotatably supported in the collection chamber 5 via a pivot. The roller 8 is a hollow cylinder with a porous structure on its surface containing pores of 1-2 cm in size.

[0038] The porous collection layer 10 is a metal mesh, specifically a molybdenum mesh, with pores of 1-2 μm in size.

[0039] The drive unit 7 is a magnetic levitation motor installed outside the collection chamber 5, ensuring full contact between the carbon nanotubes and the metal mesh under the influence of airflow. This design eliminates lubricant contamination, friction particle contamination, and mechanical vibration that may result from traditional mechanical bearings, ensuring the purity of the collection environment and the extreme smoothness of the roller 8's rotation. This is crucial for maintaining the high purity of the nanomaterial products and the uniformity of the collection layer. The roller 8 is coupled to the drive end of the magnetic levitation motor, which drives the internal roller 8 to rotate without contact via magnetic coupling. Its speed can be steplessly adjusted within the range of 1-50 rpm.

[0040] The negative pressure system includes a vacuum pump 13. The suction port of the vacuum pump 13 is connected to the interior of the roller 8, allowing airflow to be drawn away through the porous collection layer 10 and the roller 8. The vacuum pump 13 is equipped with a butterfly valve 12, which is installed between the pressure sensor 11 and the vacuum pump 13 to precisely control the suction rate and the negative pressure level within the collection chamber 5. By adjusting the opening of the butterfly valve 12, the negative pressure environment within the collection chamber 5 is stably controlled. The negative pressure value within the collection chamber 5 is 0.04-0.09 MPa.

[0041] Under the action of the negative pressure system, the airflow carries the single-walled carbon nanotubes through the deposition zone 2 of the tubular reactor 1 into the collection chamber 5, where they are adsorbed onto the porous collection layer 10.

[0042] The aforementioned continuous collection device for single-walled carbon nanotubes also includes a control unit. A negative pressure system is connected to the control unit. The control unit can adjust the operation of the negative pressure system, the drive unit 7, and the single-walled carbon nanotube synthesis reaction based on the signal from the pressure sensor 11. When the pressure inside the tubular reactor 1 and the collection chamber 5 exceeds the set safety value, relevant signals are fed back to the gas and liquid supply systems, and the reaction is immediately stopped, further ensuring safe production. Furthermore, the signal from the pressure sensor 11 can be fed back to the control unit, which can simultaneously output control commands to the actuators, liquid supply, and gas supply mechanisms of the drive unit 7, allowing for preset or real-time adjustment of process parameters.

[0043] A method for continuous collection of single-walled carbon nanotubes, employing the aforementioned continuous collection device for single-walled carbon nanotubes, includes: The gas phase reaction was carried out in tubular reactor 1 to complete the growth of single-walled carbon nanotubes; The negative pressure system is activated to establish negative pressure in the collection chamber 5, allowing the airflow carrying single-walled carbon nanotubes to enter the collection chamber 5. Start the drive unit 7 to rotate the roller 8 covered by the porous collection layer 10; Single-walled carbon nanotubes are adsorbed onto the surface of the porous collection layer 10 under negative pressure; The continuous peeling and collection of single-walled carbon nanotubes is achieved through the contact between the roller 8 and the scraper 9.

[0044] The specific explanation is as follows: 1. System preparation and startup reaction: Check the sealing of each system to ensure that the liquid, gas, and electrical circuits are functioning properly.

[0045] A protective gas (argon) is introduced into the tubular reactor 1, and the heating program is started to raise the reaction zone to the target temperature (1200℃).

[0046] Start the vacuum pump 13 of the negative pressure system, and slowly adjust the opening degree of the butterfly valve 12 to evacuate the collection chamber 5 and the connecting pipe to establish a slight negative pressure (800mbar).

[0047] 2. Growth and airflow guidance of single-walled carbon nanotubes: After the temperature in the reaction zone stabilizes, a mixture of carbon source, catalyst precursor and carrier gas is introduced into tubular reactor 1 to begin the growth of single-walled carbon nanotubes.

[0048] The generated single-walled carbon nanotube aerosol is carried by the high-speed main airflow and passes through flange 3 and corrugated pipe 4 in sequence.

[0049] 3. Dynamic adsorption and continuous collection: Start the magnetic levitation motor to drive roller 8 to rotate at a set low speed (10 rpm) at a constant speed.

[0050] Under negative pressure, single-walled carbon nanotube aerosols collide with and are firmly adsorbed onto the molybdenum mesh on the surface of roller 8. The airflow enters the internal cavity of roller 8 through the vent holes in the molybdenum mesh and the wall of roller 8, and is eventually drawn away by the vacuum pump 13.

[0051] The carbon nanotubes adsorbed on the molybdenum mesh are continuously scraped off by the scraper 9 on the side and fall into the collection chamber 5. This process repeats continuously, realizing the synchronous and uninterrupted operation of the upstream reaction and the downstream collection.

[0052] 4. Shutdown: Stop feeding the reaction materials.

[0053] Close butterfly valve 12 and air pump 13 in sequence. Wait for the air pressure in the system to rise to a slightly positive pressure (1100 mbar) before turning off the carrier gas.

[0054] Stop heating and allow the material to cool naturally to room temperature before removing it.

[0055] Optimal Examples and Results: In one specific embodiment, ethanol was used as the carbon source, ferrocene as the catalyst, and hydrogen as the carrier gas to grow single-walled carbon nanotubes at 1200°C. The negative pressure in collection chamber 5 was maintained at 800 mbar, and the molybdenum mesh roller rotated at 10 rpm. After 24 hours of continuous operation, flocculent single-walled carbon nanotubes were obtained in collection chamber 5. Figure 2 ), and only a very small amount of sediment was deposited on the inner wall of the downstream (deposition zone 2) reaction tube. Figure 3 It has achieved more than 24 hours of uninterrupted and stable operation.

[0056] Summary of advantages: This invention, through a clever combination of negative pressure guidance and dynamic collection on a rotating surface, supplemented by magnetic levitation for pollution-free drive and intelligent control, successfully overcomes the challenges of carbon nanotube deposition on the tube wall, discontinuous collection, and easy contamination in traditional methods. The device has a rational structure and is safe and controllable in operation, providing a reliable equipment foundation for the large-scale preparation and industrial application of single-walled carbon nanotubes.

[0057] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A continuous collection device for single-walled carbon nanotubes, used for collecting single-walled carbon nanotubes entering the deposition zone of a tubular reactor, characterized in that, The single-walled carbon nanotube continuous collection device includes a collection chamber, a negative pressure system, and a dynamic collection component. The dynamic collection assembly includes: a roller rotatably disposed within the collection chamber; a porous collection layer covering the outer surface of the roller for adsorbing single-walled carbon nanotubes; a driving unit for driving the roller to rotate around its axis; and a scraper disposed within the collection chamber for peeling off the single-walled carbon nanotubes attached to the porous collection layer. Under the action of the negative pressure system, the airflow carries single-walled carbon nanotubes through the deposition zone of the tubular reactor into the collection chamber, where they are adsorbed onto the porous collection layer.

2. The continuous collection device for single-walled carbon nanotubes according to claim 1, characterized in that, The drive unit is a magnetic levitation motor.

3. The continuous collection device for single-walled carbon nanotubes according to claim 1, characterized in that, The roller is hollow inside and has a porous surface. The air extraction port of the negative pressure system is connected to the interior of the roller, allowing airflow to be drawn away through the porous collection layer and the roller.

4. The continuous collection device for single-walled carbon nanotubes according to claim 1, characterized in that, The porous collection layer is a molybdenum mesh or a tungsten mesh.

5. The continuous collection device for single-walled carbon nanotubes according to claim 1, characterized in that, The tubular reactor deposition zone and the collection chamber are connected by a corrugated pipe.

6. The continuous collection device for single-walled carbon nanotubes according to claim 1, characterized in that, The continuous collection device for single-walled carbon nanotubes also includes a control unit; The collection chamber is connected to a pressure sensor; The negative pressure system is connected to the control unit; The control unit adjusts the operation of the negative pressure system, the drive unit, and the single-walled carbon nanotube synthesis reaction based on the signal from the pressure sensor.

7. The continuous collection device for single-walled carbon nanotubes according to claim 1, characterized in that, The collection chamber has a viewing window.

8. The continuous collection device for single-walled carbon nanotubes according to claim 7, characterized in that, The material of the viewing window is silicon dioxide.

9. A method for continuous collection of single-walled carbon nanotubes, characterized in that, The single-walled carbon nanotube continuous collection device according to any one of claims 1-8 is used; The method for continuous collection of single-walled carbon nanotubes includes: The growth of single-walled carbon nanotubes is achieved through a gas-phase reaction within a tubular reactor. The negative pressure system is activated to establish negative pressure in the collection chamber, allowing the airflow carrying single-walled carbon nanotubes to enter the collection chamber. Start the drive unit to rotate the roller covered with the porous collection layer; Single-walled carbon nanotubes are adsorbed onto the surface of the porous collection layer under negative pressure; The continuous peeling and collection of single-walled carbon nanotubes is achieved through the contact between the roller and the scraper.

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