Single-walled carbon nanotube continuous production apparatus and production method

Abstract

Disclosed in the present application are a single-walled carbon nanotube continuous production apparatus and production method. The production apparatus comprises a vacuum-tight box and a high-temperature growth furnace; a conveying device is provided in the vacuum-tight box, a growth substrate being placed on the conveying device; a sample feeding cylinder corresponding to the conveying device is provided in the vacuum-tight box; the vacuum-tight box is connected to a first vacuum pump; a growth quartz tube is provided in the high-temperature growth furnace, the growth quartz tube being connected to an outlet of the vacuum-tight box; the growth quartz tube is further connected to a carbon source supply system and a second vacuum pump; the production apparatus further comprises a sample acquiring cylinder and a cooling quartz tube, the cooling quartz tube being connected to the growth quartz tube; the sample acquiring cylinder is used for discharging out of the high-temperature growth furnace the growth substrate loaded with a single-walled carbon nanotube, and then feeding into the cooling quartz tube said growth substrate to be cooled. The production apparatus and the production method not only can produce and obtain relatively pure and uniform single-walled carbon nanotubes, but also exhibit a high degree of automation and high production efficiency, and can achieve the continuous production of the single-walled carbon nanotubes.

Description

A continuous production equipment and method for single-walled carbon nanotubes Technical Field

[0001] This invention relates to the field of carbon nanotube technology, and in particular to a continuous production equipment and method for single-walled carbon nanotubes. Background Technology

[0002] Carbon nanotubes (CNTs) are tubular structures formed by a continuous hexagonal arrangement of carbon atoms in their walls; they can be understood as tubular structures formed by rolling up graphene. Single-walled carbon nanotubes can be viewed as seamless, hollow, two-dimensional tubular structures formed by rolling up a single layer of graphene along a specific direction. This unique structure endows single-walled carbon nanotubes with excellent mechanical properties, chirality-dependent electrical / semiconductor properties, ballistic transport characteristics, excellent flexibility, and high chemical stability, making them promising for widespread application in high-tech fields such as aerospace, nanoelectronic devices, and more.

[0003] Currently, the main methods for preparing carbon nanotubes include: arc discharge method, laser ablation method, chemical vapor deposition (CVD), solid-state pyrolysis method, glow discharge method, gas combustion method, and polymerization synthesis method. CVD technology has become the mainstream method for preparing single-walled carbon nanotubes due to its advantages such as simple process and equipment, low cost, and controllable structure. Commercially available CVD methods for producing carbon nanotubes mainly involve impregnating / coating a catalyst onto a substrate, such as porous zeolite, MgO, or silicon substrates. Under appropriate temperature and carbon source supply conditions, carbon nanotubes can grow from the catalyst supported on the substrate.

[0004] Current chemical vapor deposition (CVD) equipment for carbon nanotube production has a low level of automation and low production efficiency, making it impossible to mass-produce single-walled carbon nanotubes. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a continuous production equipment and method for single-walled carbon nanotubes. This equipment and method not only produce relatively pure and uniform single-walled carbon nanotubes, but also feature a high degree of automation and high production efficiency, enabling continuous production of single-walled carbon nanotubes.

[0006] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0007] The present invention provides a continuous production equipment for single-walled carbon nanotubes, including a vacuum sealed chamber and a high-temperature growth furnace;

[0008] The vacuum chamber is equipped with a conveying device on which the growth substrate is placed; the vacuum chamber is also equipped with a sample delivery cylinder corresponding to the conveying device; the vacuum chamber is connected to a vacuum pump.

[0009] The high-temperature growth furnace is equipped with a growth quartz tube, which is connected to the outlet of the vacuum sealed box; the sample delivery cylinder can deliver the growth substrate into the growth quartz tube; the growth quartz tube is also connected to a carbon source supply system and a vacuum pump.

[0010] It also includes a sampling cylinder and a cooling quartz tube, the cooling quartz tube being connected to the growth quartz tube; the sampling cylinder is used to send the growth substrate carrying the grown single-walled carbon nanotubes out of the high-temperature growth furnace and then into the cooling quartz tube for cooling.

[0011] Furthermore, the growth substrate is a quartz support loaded with catalyst particles.

[0012] Furthermore, the conveying device is a conveyor belt, which is driven by a motor.

[0013] Furthermore, a gate valve is provided at the outlet of the vacuum sealing box and between the growth quartz tube and the cooling quartz tube.

[0014] Furthermore, the piston rod of the sampling cylinder extends into the growth quartz tube, and its end is provided with an elastic hook for hooking the growth substrate carrying the grown single-walled carbon nanotubes away from the growth quartz tube.

[0015] Furthermore, both the growth quartz tube and the cooling quartz tube are provided with support seats for supporting the growth substrate.

[0016] Furthermore, the carbon source supply system is used to provide a carbon source mixture, which includes a reducing gas, a protective gas, and a carbon source gas containing ethanol.

[0017] Another aspect of the present invention provides a method for producing single-walled carbon nanotubes using the above-described continuous production equipment for single-walled carbon nanotubes, comprising the following steps:

[0018] The growth substrate is placed on the conveying device, and the vacuum pump starts working to extract the gas from the vacuum sealing box, so that the vacuum sealing box reaches a certain pressure value.

[0019] After the conveying device delivers the growth substrate to the accurate position, the sample delivery cylinder is activated to send the growth substrate into the growth quartz tube in the high-temperature growth furnace. Vacuum pump two starts working to draw the growth quartz tube to negative pressure and maintain rated power operation.

[0020] The carbon source mixed gas provided by the carbon source supply system is introduced into the growth quartz tube, and carbon nanotubes grow on the growth substrate under high temperature heating conditions.

[0021] After growth is complete, the sampling cylinder sends the growth substrate carrying single-walled carbon nanotubes out of the high-temperature growth furnace and then into a cooling quartz tube for cooling; while cooling, the next growth substrate is conveyed into place by the conveying device, and the above process is repeated.

[0022] Furthermore, the pressure inside the growth quartz tube is controlled to be 0.5-3 kPa.

[0023] Furthermore, the high-temperature heating during growth is 500-1000℃.

[0024] The beneficial effects of this invention are:

[0025] (1) In this invention, the growth substrate is first sent into a vacuum sealed box, and the gas is extracted by vacuum pump one to ensure an inert environment when entering the growth quartz tube.

[0026] (2) The present invention uses a sample delivery cylinder built into a vacuum sealed box to deliver the growth substrate, which can reduce equipment costs, make operation more convenient, and achieve more accurate and efficient sample delivery operation.

[0027] (3) The present invention uses a vacuum pump to evacuate the quartz tube to make the environment inside the quartz tube low negative pressure, specifically controlled at 0.5-3Kpa. This low negative pressure state can improve the purity and uniformity of single carbon nanotubes and improve the quality of single carbon nanotubes.

[0028] (4) The present invention uses a sampling cylinder to send the growth substrate carrying single-walled carbon nanotubes out of the high-temperature growth furnace through the elastic hook at the end of its piston rod, and then into the cooling quartz tube for cooling. This sampling cylinder can be well adapted to the growth quartz tube, improves the convenience of sampling operation, reduces equipment cost, and can achieve more accurate and efficient sampling operation;

[0029] (5) The present invention has designed a cooling quartz tube at the outlet of the high temperature growth furnace, which can facilitate the timely cooling of single-wall carbon nanotube products without the need to transfer them to other cooling equipment for cooling, thereby improving production efficiency.

[0030] (6) While the previous single-walled carbon nanotube is in the cooling process, the next growth substrate is transported to the position by the conveying device to produce the next single-walled carbon nanotube, thus realizing continuous production.

[0031] The production equipment of this invention is scaled up to more than 100 times that of traditional equipment, and the reaction pressure and temperature are reasonably controlled. It can not only produce relatively pure and uniform single-walled carbon nanotubes, but also has a high degree of automation and high production efficiency, enabling continuous production of single-walled carbon nanotubes. Attached Figure Description

[0032] Figure 1 is a three-dimensional structural schematic diagram of the single-walled carbon nanotube continuous production equipment of the present invention.

[0033] Figure 2 is a partial structural schematic diagram of the single-walled carbon nanotube continuous production equipment of the present invention.

[0034] Figure 3 is a schematic diagram of part of the internal structure of the continuous production equipment for single-walled carbon nanotubes of the present invention.

[0035] Figure 4 is an enlarged schematic diagram of the elastic hook.

[0036] Figure 5 is an electron microscope image of the single-walled carbon nanotubes produced by this invention.

[0037] In the diagram, 1: Vacuum sealed chamber; 2: High-temperature growth furnace; 3: Conveying device; 4: Growth substrate; 5: Sample delivery cylinder; 6: Growth quartz tube; 7: Sampling cylinder; 701: Elastic hook; 7011: Fixing plate; 7012: Stop plate; 7013: Movable hook plate; 7014: Spring; 8: Support base; 9: Cooling quartz tube; 10: Insert valve; 11: Vacuum pump one; 12: Vacuum pump two; 13: Diaphragm inlet valve; 14: Connecting quartz tube. Detailed Implementation

[0038] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0039] In the description of this invention, it should be understood that the terms "front", "rear", "left", "right", "up", "down", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] As shown in Figures 1 to 4, the present invention provides a continuous production equipment for single-walled carbon nanotubes, including a vacuum sealed chamber 1 and a high-temperature growth furnace 2.

[0041] The vacuum-sealed chamber 1 is equipped with a conveying device 3, on which the growth substrate 4 is placed. A gate valve 10 is located at the inlet of the vacuum-sealed chamber 1. In this embodiment, the conveying device 3 is a conveyor belt driven by a motor. The growth substrate 4 is a quartz carrier loaded with catalyst particles. The catalyst particles are made by loading transition metals such as Fe and Co onto a carrier, which is zeolite powder. The total content of the loaded metal catalyst accounts for 1%-10% of the mass of the catalyst particles. Multiple slots are arranged on the conveyor belt, and the quartz carrier is placed in these slots. In this embodiment, the number of growth substrates placed on the conveyor belt at one time is designed to be 10 for continuous production. The vacuum-sealed chamber 1 is also equipped with a sample delivery cylinder 5 corresponding to the conveying device 3. The piston rod of the sample delivery cylinder 5 corresponds to the conveyor belt and is used to push the quartz carrier loaded with catalyst particles on the conveyor belt. The vacuum-sealed chamber 1 is connected to a vacuum pump 11, used to extract gas from the vacuum-sealed chamber 1 to prepare a negative pressure growth environment for the next step of growing quartz tubes.

[0042] The vacuum sealing chamber 1 is also equipped with a gate valve 10 at its outlet; the high-temperature growth furnace 2 is equipped with a growth quartz tube 6, which is connected to the outlet of the vacuum sealing chamber 1 via a connecting quartz tube 14; specifically, one end of the connecting quartz tube 14 is connected to the gate valve 10 at the outlet of the vacuum sealing chamber 1, and the other end is connected to the growth quartz tube 6 via a connecting flange; the growth quartz tube 6 is also equipped with a support seat 8 for supporting the growth substrate 4; the sample delivery cylinder 5 can push the growth substrate 4 into the support seat 8 in the growth quartz tube 6; the growth quartz tube 6 is also connected to a carbon source supply system (not shown in the figure) and a vacuum pump 12. Specifically, the carbon source supply system includes a reducing gas inlet pipeline, a protective gas inlet pipeline, a carbon source gas inlet pipeline, and a mixing tank. The reducing gas, protective gas, and carbon source gas are mixed in the mixing tank and then introduced into the growth quartz tube 6 through the pipeline. A diaphragm inlet valve 13 is also provided on the pipeline for introducing the carbon source gas mixture into the growth quartz tube 6; the carbon source gas contains ethanol, and in addition to ethanol, it may also contain at least one of the hydrocarbons such as acetylene, ethylene, hexane, methane, propylene, and butane; the reducing gas or protective gas is selected from at least one of nitrogen, hydrogen, argon, and helium. The vacuum pump 12 can evacuate the growth quartz tube 6 to a vacuum of 0.5-3 kPa.

[0043] The production equipment also includes a sampling cylinder 7 and a cooling quartz tube 9. The inlet end of the cooling quartz tube 9 is connected to the outlet end of the growth quartz tube 6. Both the inlet and outlet ends of the cooling quartz tube 9 are connected to a gate valve. The cylinder body of the sampling cylinder 7 is fixed in the cooling quartz tube 9, and its piston rod can extend into the growth quartz tube 6. The end of the piston rod of the sampling cylinder 7 is provided with an elastic hook 701. Specifically, the elastic hook 701 includes a fixed plate 7011 and a stop plate 7012 fixed to the piston rod of the sampling cylinder 7, and a movable hook plate 7013 rotatably connected to the piston rod via a pin. A spring 7014 is provided between the fixed plate 7011 and the stop plate 7012, and the spring 7014 also passes through the stop plate 7012 and is connected to the movable hook plate 7013. During the process of the piston rod of the sampling cylinder 7 extending into the growth quartz tube 6, the movable hook plate 7013 can be flipped upward to facilitate the extension of the piston rod. After the piston rod of the sampling cylinder 7 is inserted into position, the elastic hook 701 hooks the quartz carrier (the movable hook plate rests against the edge of the quartz carrier) and pulls the quartz carrier away from it. During the pulling process, the movable hook plate 7013 will not flip due to the stop plate 7012, thus realizing the action of pulling away the quartz carrier.

[0044] After the growth substrate 4 containing the grown single-walled carbon nanotubes is sent out of the high-temperature growth furnace 2, it is sent into the cooling quartz tube 9 for cooling. The cooling quartz tube 9 is also provided with a support seat 8 for supporting the growth substrate 4.

[0045] The production equipment of the present invention also includes a control device, which drives and controls the execution components in the production equipment to complete the corresponding operations via a PLC.

[0046] The method for producing single-walled carbon nanotubes using the above-mentioned continuous production equipment includes the following steps:

[0047] First, open the slide valve 10 at the inlet of the vacuum sealing chamber 1, and place the quartz carrier (growth substrate) loaded with catalyst particles into the slot of the conveying device 3. Ten carriers can be placed at a time. After placement, the control device controls the slide valve at the inlet of the vacuum sealing chamber 1 to close, and the vacuum pump 11 starts working to extract the gas from the vacuum sealing chamber 1, so that the pressure gauge on the chamber itself shows a pressure below 30 Pa.

[0048] After the conveying device 3 conveys the quartz carrier loaded with catalyst particles to the accurate position, the gate valve at the outlet of the vacuum sealed box 1 opens, the sample delivery cylinder 5 actuates, and sends the quartz carrier loaded with catalyst particles into the growth quartz tube 6 in the high-temperature growth furnace 2; the sample delivery cylinder 5 resets, the gate valve at the outlet of the vacuum sealed box 1 closes; the vacuum pump 12 starts working, drawing the growth quartz tube 6 to a negative pressure (0.5-3Kpa) and maintaining rated power.

[0049] Open the diaphragm inlet valve 13 to introduce the carbon source mixture provided by the carbon source supply system into the growth quartz tube 6. Under high-temperature heating conditions, carbon nanotubes grow on the growth substrate for 10-30 minutes. The high-temperature heating temperature during growth is 500-1000℃. During the growth process, the pumping speed of vacuum pump 12 is 500-1000 L / min. With the cooperation of diaphragm inlet valve 13 and vacuum pump 12, the pressure difference between the upstream and downstream of the growth quartz tube 6 is controlled at 0-0.3 kPa.

[0050] After growth is complete, the inlet valve 10 of the cooling quartz tube 9 is opened, and the sampling cylinder 7 delivers the growth substrate carrying single-walled carbon nanotubes out of the high-temperature growth furnace 2, and then into the cooling quartz tube 9 for cooling. The inlet valve of the cooling quartz tube 9 is then closed. Simultaneously, the next growth substrate 4 is conveyed into place by the conveying device 3, and the above process is repeated. After a period of time, when the laser temperature gun detects that the temperature of the quartz carrier carrying single-walled carbon nanotubes in the cooling quartz tube 9 has cooled to below 300°C, the inlet valve at the outlet of the cooling quartz tube 9 is opened. The conveying device (such as a conveyor belt) connecting to the outlet of the cooling quartz tube delivers the quartz carrier carrying single-walled carbon nanotubes, and then the grown single-walled carbon nanotubes are collected and stored. Under the control of the control device, the cycle of sample delivery cylinder injection-growth-sampling cylinder sampling-product cooling-sampling storage continues until all quartz carriers loaded with catalyst particles are exhausted.

[0051] If regrowth is required, simply place a quartz carrier loaded with catalyst particles onto the conveyor device 3. The carbon nanotube powder growth will continue until the process is manually terminated. Except for the sample placement and material handling, which require manual intervention, the remaining steps are completed by PLC (Programmable Logic Controller) driving the corresponding execution components, achieving continuous and uninterrupted production of carbon nanotube powder materials, significantly saving time and labor costs. This production equipment can also be further scaled up according to actual conditions to achieve even higher production efficiency.

[0052] The production equipment and method of this invention can achieve a production rate of 1-100 g / h for single-walled carbon nanotubes. As shown in Figure 5, the single-walled carbon nanotubes produced by this invention are relatively pure and have good uniformity. Single-walled carbon nanotubes with a diameter of approximately 1-2 nanometers (as shown in Figure 5(d)) exist in bundles, without amorphous carbon, multi-walled carbon nanotubes (MWCNTs), or nanoparticles as byproducts. Scanning electron microscopy (SEM) images (Figure 5(a), (b), and (c)) show that single-walled carbon nanotube bundles with a thickness of approximately 10 nanometers surround zeolite particles of approximately 300 nanometers in a spiderweb-like pattern, without any other byproducts.

[0053] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0054] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A continuous production equipment for single-walled carbon nanotubes, characterized in that, Including vacuum-sealed chambers and high-temperature growth furnaces; The vacuum chamber is equipped with a conveying device on which the growth substrate is placed; the vacuum chamber is also equipped with a sample delivery cylinder corresponding to the conveying device; the vacuum chamber is connected to a vacuum pump. The high-temperature growth furnace is equipped with a growth quartz tube, which is connected to the outlet of the vacuum sealed box; the sample delivery cylinder can deliver the growth substrate into the growth quartz tube; the growth quartz tube is also connected to a carbon source supply system and a vacuum pump. It also includes a sampling cylinder and a cooling quartz tube, the cooling quartz tube being connected to the growth quartz tube; the sampling cylinder is used to send the growth substrate carrying the grown single-walled carbon nanotubes out of the high-temperature growth furnace and then into the cooling quartz tube for cooling.

2. The continuous production equipment for single-walled carbon nanotubes according to claim 1, characterized in that, The growth substrate is a quartz support loaded with catalyst particles.

3. The continuous production equipment for single-walled carbon nanotubes according to claim 1, characterized in that, The conveying device is a conveyor belt, which is driven by a motor.

4. The continuous production equipment for single-walled carbon nanotubes according to claim 1, characterized in that, A gate valve is provided at the outlet of the vacuum sealing box and between the growth quartz tube and the cooling quartz tube.

5. The continuous production equipment for single-walled carbon nanotubes according to claim 1, characterized in that, The piston rod of the sampling cylinder extends into the growth quartz tube, and its end is provided with an elastic hook for hooking the growth substrate carrying the grown single-walled carbon nanotubes away from the growth quartz tube.

6. The continuous production equipment for single-walled carbon nanotubes according to claim 1, characterized in that, Both the growth quartz tube and the cooling quartz tube are equipped with support seats for supporting the growth substrate.

7. The continuous production equipment for single-walled carbon nanotubes according to claim 1, characterized in that, The carbon source supply system is used to provide a carbon source mixture, which includes a reducing gas, a protective gas, and a carbon source gas containing ethanol.

8. A method for producing single-walled carbon nanotubes using a continuous production apparatus for single-walled carbon nanotubes as described in any one of claims 1-7, characterized in that, Includes the following steps: The growth substrate is placed on the conveying device, and the vacuum pump starts working to extract the gas from the vacuum sealing box, so that the vacuum sealing box reaches a certain pressure value. After the conveying device delivers the growth substrate to the accurate position, the sample delivery cylinder is activated to send the growth substrate into the growth quartz tube in the high-temperature growth furnace. Vacuum pump two starts working to draw the growth quartz tube to negative pressure and maintain rated power operation. The carbon source mixed gas provided by the carbon source supply system is introduced into the growth quartz tube, and the carbon nanotubes grow on the growth substrate under high temperature heating conditions. After growth is complete, the sampling cylinder sends the growth substrate carrying single-walled carbon nanotubes out of the high-temperature growth furnace and then into a cooling quartz tube for cooling; while cooling, the next growth substrate is conveyed into place by the conveying device, and the above process is repeated.

9. The method for producing single-walled carbon nanotubes according to claim 8, characterized in that, The pressure inside the quartz tube for growth is controlled at 0.5-3 kPa.

10. The method for producing single-walled carbon nanotubes according to claim 8, characterized in that, The high-temperature heating during growth is 500-1000℃.

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