CN108408716B - Carbon nanotube preparation system - Google Patents
Carbon nanotube preparation system Download PDFInfo
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- CN108408716B CN108408716B CN201810253208.2A CN201810253208A CN108408716B CN 108408716 B CN108408716 B CN 108408716B CN 201810253208 A CN201810253208 A CN 201810253208A CN 108408716 B CN108408716 B CN 108408716B
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- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
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- C01B2202/00—Structure or properties of carbon nanotubes
- C01B2202/20—Nanotubes characterized by their properties
- C01B2202/22—Electronic properties
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- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2202/00—Structure or properties of carbon nanotubes
- C01B2202/20—Nanotubes characterized by their properties
- C01B2202/26—Mechanical properties
Abstract
The invention relates to a carbon nano tube preparation system, which comprises a pre-growth tube and is used for the preliminary reaction of raw materials before the carbon nano tube is generated. The atomizer is used for atomizing the carbon nano tube raw material and then spraying the atomized carbon nano tube raw material into the pre-growth tube. The atomizer is arranged at the front end of the pre-growth tube and is provided with a spray output tube which extends into the pre-growth tube. A growth tube for generating carbon nano-tube, and continuously growing the generated carbon nano-tube. The front end of the growth tube is hermetically connected with the rear end of the pre-growth tube. And the air curtain generator is used for forming an air curtain wrapping the atomized air flow around the outlet of the spray output pipe, and the air curtain extends along the extending direction of the parallel pre-growth pipe. The air curtain generator is arranged in the pre-growth tube. The system of the present invention forms an air curtain around the spray delivery tube. On one hand, laminar flow is formed in the pre-growth tube through the air curtain to stabilize air flow, on the other hand, the adhesion of impurities or carbon nano tubes is avoided, and the continuous growth of the carbon nano tubes is ensured.
Description
Technical Field
The invention relates to carbon nanotube preparation equipment, in particular to a carbon nanotube preparation system.
Background
As a typical one-dimensional nano material, the carbon nano tube material has excellent mechanical, thermal and electrical properties and is wide in application field. Many colleges, research institutions and companies at home and abroad research how to synthesize carbon nanotube materials with more excellent macroscopic properties.
The current popular carbon nanotube synthesis method is based on Chemical Vapor Deposition (CVD) to prepare macroscopic carbon nanotube materials, such as carbon nanotube films and carbon nanotube fibers. However, there is a great difference between laboratory-stage research and industrial mass production, especially in CVD process, as the equipment size is enlarged, the influence of instability factors is increased, many laboratory-stage problems are not shown, and the synthesis and quality of carbon nanotube material are significantly affected during industrialization. Therefore, how to improve the stability of the process and the continuity of the production becomes an important issue in the industrialization of carbon nanotubes.
In the prior art, there is a method of guiding and pulling the growth direction and continuous growth of carbon nanotubes by means of setting an electric field or a magnetic field. But in the industrialization process, the complexity and the control difficulty of the equipment are increased, and the mature application is difficult. Therefore, how to easily and feasibly improve the stability and continuity of the process is still a problem to be solved.
Disclosure of Invention
Therefore, in order to solve the problem of how to achieve the stability and continuity of carbon nanotube production, it is necessary to provide a carbon nanotube synthesis system, which can ensure the stability of air flow in the process, ensure the continuous and stable synthesis of carbon nanotubes, and promote the industrialization of carbon nanotube material production.
The invention provides a carbon nanotube preparation system, which is characterized by comprising:
the pre-growth tube is used for the preliminary reaction of raw materials before the carbon nano tube is generated;
the atomizer is used for atomizing the carbon nano tube raw material and then spraying the atomized carbon nano tube raw material into the pre-growth tube; the atomizer is arranged at the front end of the pre-growth pipe and provided with a spray output pipe, and the spray output pipe extends into the pre-growth pipe;
a growth tube for generating carbon nanotubes and performing continuous growth of the generated carbon nanotubes; the front end of the growth tube is hermetically connected with the rear end of the pre-growth tube;
the air curtain generator is used for forming an air curtain wrapping atomized air flow around the outlet of the spray output pipe, and the air curtain extends along the direction parallel to the extension direction of the pre-growth pipe; the air curtain generator is arranged in the pre-growth tube.
According to the carbon nanotube preparation system, the air curtain is formed around the spray output pipe of the atomizer. On one hand, laminar flow is formed in the pre-growth tube through the air curtain to stabilize air flow, on the other hand, the adhesion of impurities or carbon nano tubes is avoided, and the continuous growth of the carbon nano tubes is ensured.
In one embodiment, the air curtain generator comprises at least one air curtain forming plate, and the air curtain forming plate is provided with a plurality of air holes.
In one embodiment, the air curtain forming plate is annular, and the spray output pipe is positioned in the central hollow of the air curtain forming plate; the air holes are radially distributed on the air curtain forming plate.
In one embodiment, the edge profile of the gas curtain forming plate is matched with the inner wall of the pre-growth tube, and at least part of the air holes are positioned in the edge area of the gas curtain forming plate to form gas curtain flow clinging to the inner wall of the pre-growth tube.
In one embodiment, the gas curtain generator further comprises at least one gas inlet for inputting carrier gas into the pre-growth tube, the gas inlet being located at the front end of the pre-growth tube.
In one embodiment, the pre-growth tube and the growth tube are connected through a tubular first insulating piece.
In one embodiment, the temperature in the pre-growth tube is 200-950 ℃;
the temperature in the growth tube is 1100-1600 ℃.
In one embodiment, the pre-growth tube comprises a first pre-growth section and a second pre-growth section;
the first pre-growth section is close to the front end of the pre-growth pipe, and the second pre-growth section is close to the rear end of the pre-growth pipe;
the temperature in the first pre-growth section is different from the temperature in the second pre-growth section.
In one embodiment, a first temperature controller is arranged outside the first pre-growth section, and a second temperature controller is arranged outside the second pre-growth section;
the first pre-growth section and the second pre-growth section are connected through a second heat insulation piece.
In one embodiment, the first temperature controller comprises a first heating device and a first cooling device;
the second temperature controller includes a second heating device and a second cooling device.
In one embodiment, the temperature in the first pre-growth section is 200-300 ℃;
the temperature in the second pre-growth section is 700-950 ℃.
In one embodiment, the inner wall of the growth tube is provided with an anti-sticking coating for preventing the nano material from being attached to the inner wall of the growth tube.
In one embodiment, the release coating is zirconium oxide or zinc oxide.
In one embodiment, the growth tube is provided with vent holes for introducing carrier gas to enable the carrier gas to form a gas protection layer on the inner wall surface of the growth tube, and the vent holes penetrate through the tube wall of the growth tube and are uniformly distributed.
In one embodiment, an angle between an axial direction of the vent hole and an extending direction of the growth tube is less than 5 degrees.
In one embodiment, the atomizer comprises an ultrasonic atomizing nozzle for uniformly mixing and atomizing the raw materials and then spraying the raw materials, and an ultrasonic controller for adjusting the numerical value of ultrasonic waves.
In one embodiment, the nanomaterial synthesis system is upright or horizontal.
In one embodiment, the pre-growth tube and the growth tube are vertically arranged, and the atomizer is vertically arranged along the extending direction of the pre-growth tube and the growth tube.
In one embodiment, the air curtains are distributed in parallel along the direction of gravity.
Drawings
FIG. 1 is a schematic structural diagram of one embodiment of an industrial continuous carbon nanotube material production system;
FIG. 2 is a schematic structural diagram of a carbon nanotube synthesis system according to one embodiment of the present invention;
FIG. 3 is a schematic view of the structure of an air curtain forming plate of the embodiment of FIG. 2; wherein fig. 3a is a front view of the air curtain forming plate, fig. 3B is a cross-sectional view of the air curtain forming plate taken along B-B, and fig. 3c is a partial enlarged view of fig. 3B at the dotted line portion D;
FIG. 4 is a schematic view of the structure of an air curtain forming plate of another embodiment of FIG. 2; wherein fig. 4a is a front view of the air curtain forming plate, fig. 4b is a cross-sectional view of the air curtain forming plate taken along C-C, and fig. 4C is a partially enlarged view of fig. 4b at the broken line portion E.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
At present, the preparation method of carbon nanotubes basically decomposes a carbon source into atomic or ionic forms by using various external energies, and then generates a carbon nanotube macroscopic material by aggregation. Generally, there are three main methods for preparing carbon nanotubes, namely, arc discharge, laser ablation, and chemical vapor deposition. In the industrial production, Chemical Vapor Deposition (CVD) is often used to prepare carbon nanotubes.
The CVD preparation of carbon nano tube mainly uses gaseous or liquid hydrocarbon substance as carbon source, after the carbon source is atomized, at proper temperature, catalyst is added, the carbon source is cracked on the surface of catalyst particles into carbon atom clusters, then the carbon atoms are recombined to form carbon nano tube, and then carbon nano tube materials with different forms are obtained by a specially designed collecting device. Wherein, the catalyst and the carbon source are carried into the furnace body together by the carrier gas, and the preparation method is called as floating catalytic carbon nanotube preparation technology. The invention mainly adopts the floating catalysis carbon nanotube process to prepare the carbon nanotube.
Fig. 1 is a schematic structural diagram of an embodiment of a production system for industrially continuously producing carbon nanotube material. As shown in fig. 1, the carbon nanotube production system 100 includes a carbon nanotube preparation system 200, a carbon nanotube collection system 300, and an exhaust system 400. The carbon nanotube preparation system 200 is used to synthetically prepare raw materials into continuous carbon nanotubes. The carbon nanotube collecting system 300 is used to compact and process the prepared carbon nanotubes into a desired material, and to collect the same. The carbon nanotube collection system 300 can process carbon nanotubes into a wire or a thin film sheet and then collect the carbon nanotubes into a roll. The exhaust system 400 is used to collect and uniformly treat the reacted gas to prevent the harmful gas in the production system 100 from being exhausted to the atmosphere and prevent the residual gas in the production system 100 from interfering with the stability of the internal gas flow.
Fig. 2 is a schematic structural diagram of a carbon nanotube preparation system according to an embodiment of the present invention. As shown in fig. 2, the carbon nanotube preparing system 200 includes a pre-growth tube 210, an atomizer 220, a growth tube 230, and a gas curtain generator 240. The pre-growth tube 210 is used for the preliminary reaction of the raw materials before the carbon nanotubes are grown. The atomizer 220 is used for atomizing the carbon nanotube raw material and then spraying the atomized carbon nanotube raw material into the pre-growth tube 210. The atomizer 220 is disposed at the front end of the pre-growth tube 210. The atomizer 220 has a spray outlet pipe 221, and the spray outlet pipe 221 extends into the pre-growth pipe 210. The growth tube 230 is used for the generation of carbon nanotubes and the continuous growth of the generated carbon nanotubes. The front end of the growth tube 230 is sealingly attached to the back end of the pre-growth tube.
As shown in fig. 2, in one embodiment, the nebulizer 220 further comprises a peristaltic pump 222, an ultrasonic controller 223, and an ultrasonic nebulizing nozzle 224. After the reaction raw materials are uniformly mixed in the peristaltic pump 222, the ultrasonic wave value is adjusted by the ultrasonic controller 223, and the reaction raw materials enter the pre-growth tube 210 through the ultrasonic atomizing nozzle 224 and the atomizing output tube 221.
In one embodiment, the carbon source is a gas or liquid carbon source, and may be acetylene, ethanol, methane, ethylene, propylene, butylene, n-hexane, carbon monoxide, benzene, or other hydrocarbon.
In one embodiment, the catalyst may be any one or combination of transition metals such as iron, cobalt, nickel, etc., and their oxides or other compounds.
In one embodiment, a catalyst precursor may be used that, under certain temperature conditions,the catalyst precursor decomposes to produce metal atoms. The diameter of the catalyst particles determines the diameter of the carbon nanotubes, so that the carbon nanotubes with higher purity and more uniform size distribution can be grown by selectively controlling the type and the particle size of the catalyst. In one embodiment, the catalyst precursor may be ferrocene Fe (C)5H5)2。
In one embodiment, the feedstock may also include a promoter for increasing the activity of the catalyst. The promoter may be thiophene, other sulfur-containing compounds, or a combination thereof. The promoter may be tetrahydrothiophene C4H8S。
In one embodiment, a carrier gas may be introduced into the atomizer 220. The liquid carbon source and other materials are atomized and then changed into droplets with uniform distribution, and the droplets carry the materials with the carrier gas to enter the pre-growth tube 210. The carrier gas may be H2He or any other inert gas. In one embodiment, the carrier gas may be H2And Ar. The introduction of carrier gas is beneficial to controlling the atomization state of the atomized liquid carbon source, so that the atomized liquid carbon source can quickly reach the high-temperature reaction region in the growth tube 230, and the continuity and stability of raw material supply can be maintained.
In one embodiment, the temperature within the spray delivery tube 221 ranges from 100 ℃ to 250 ℃. To prevent the mixed raw material in the spray output pipe 221 from being condensed on the inner wall of the spray output pipe 221.
In one embodiment, the total flow rate of the carrier gas in the atomizer is controlled to be 1-100L/min, the injection rate of the liquid carbon source is controlled to be 10-1500ml/h, and the injection flow rate of the gas carbon source is controlled to be 1-100L/min. So as to ensure that the raw material input and the carbon nano tube synthesis rate are basically consistent, and the method is beneficial to the continuity of the carbon nano tube production.
In one embodiment, pre-growth tube 210 has a front end and a back end opposite the front end. An elongate channel is defined between the front end and the rear end.
In one embodiment, the spray output tube 221 of the atomizer 220 is sealingly connected to the forward end of the pre-growth tube 210. The spray delivery tube 221 may be sealingly attached to the front end of the pre-growth tube 210 by providing a flange.
In one embodiment, the tube diameter of pre-growth tube 210 and the tube diameter of growth tube 230 are equal.
In one embodiment, the pre-growth tube 210 has a tube diameter of 50-500mm and a length of 200-500 mm. The length of the growth tube 230 is 500-2000 mm.
Referring to fig. 2, the carbon nanotube preparing system 200 further includes an air curtain generator 240. The air curtain generator 240 is configured to form an air curtain around the outlet of the spray outlet pipe 221, the air curtain extending in a direction (a) parallel to the direction of extension of the pre-growth pipe 210. The air curtain generator 240 is disposed within the pre-growth tube 210.
It is understood that in the CVD process, the gas is easily turbulent in the furnace body, which is not favorable for the stability of the subsequent process. Particularly, in the industrial process, the difficulty of controlling the stability of the gas flow is increased after the size of the equipment is enlarged, and the gas should be prevented from forming a turbulent flow in the carbon nanotube preparing system 200 as much as possible. It is desirable to have a stable laminar flow of gas. In the prior art, a carrier gas is generally introduced into the raw material injection device to improve the uniformity of the gasification of the liquid carbon source. And a liner tube is arranged between the raw material injection device and the reaction tube to guide the growth direction of the carbon nano tube. However, at the interface between the liner tube and the reaction tube, turbulence is generated at the interface due to the change in cross-sectional area. On the other hand, with the increase of the reaction time, impurities generated in the reaction are accumulated at the tail end of the liner tube, namely, at the junction of the liner tube and the reaction tube, so that the carbon nanotube is easily adhered at the tube wall at the tail end of the liner tube, the carbon nanotube is broken, and the continuous growth of the carbon nanotube is directly influenced. Therefore, the current technology still has shortcomings in the aspects of stable control of the gas flow and prevention of the carbon nanotube breakage, which is not favorable for stable and continuous floating process. Particularly, in a large-diameter furnace tube floating catalytic reaction system, the defects are more obvious.
The above technical solution of the present invention is to eliminate the conventional liner tube and form an air curtain around the spray output tube 221 of the atomizer 220. On one hand, laminar flow is formed in the pre-growth tube through the air curtain to stabilize air flow, on the other hand, the adhesion of impurities or carbon nano tubes is avoided, and the continuous growth of the carbon nano tubes is ensured.
In one embodiment, the air curtain generator 240 includes at least one air curtain forming plate 241, and the air curtain forming plate 241 has a plurality of air holes formed therein.
FIG. 3 is a schematic structural view of an air curtain forming plate of the embodiment of FIG. 2; wherein fig. 3a is a front view of the air curtain forming plate, fig. 3B is a cross-sectional view of the air curtain forming plate taken along B-B, and fig. 3c is a partially enlarged view of fig. 3B at the dotted line portion D. Referring to fig. 2 and 3, the air curtain forming plate 241 is annular, and the spray output pipe 221 is located at the central hollow of the air curtain forming plate 241. The air holes are radially distributed on the air curtain forming plate 241.
In one embodiment, the edge profile of the gas curtain forming plate 241 matches the inner wall of the pre-growth tube 210, and at least some of the gas holes are located in the edge region of the gas curtain forming plate 241 to form a gas curtain flow against the inner wall of the pre-growth tube 210.
As shown in fig. 3c, the air holes of the air curtain forming plate 241 are straight holes with uniform diameters.
In one embodiment, the number of the air curtain forming plates 241 may be plural. The plurality of air curtain forming plates 241 are stacked one on another in the extending direction of the pre-growth tube 210. The plurality of air curtain forming plates 241 are in parallel relationship with each other.
In one embodiment, there are 1-4 air curtain forming plates 241 in the air curtain generator 240.
FIG. 4 is a schematic view of the structure of an air curtain forming plate of another embodiment of FIG. 2; wherein fig. 4a is a front view of the air curtain forming plate, fig. 4b is a cross-sectional view of the air curtain forming plate taken along C-C, and fig. 4C is a partially enlarged view of fig. 4b at the broken line portion E. As shown in fig. 4c, the air holes of the air curtain forming plate 241 may be flared holes with a wide front hole and a narrow back hole.
In one embodiment, the air holes are symmetrically distributed along the central hollow portion of the air curtain forming plate 241, and the number of the air holes on one side is 2-6. The diameter of the air holes may be 10 cm.
As shown in fig. 2, the gas curtain generator 240 further includes at least one gas inlet 242 for inputting carrier gas into the pre-growth tube, the gas inlet 242 being located at the front end of the pre-growth tube 210.
In one embodiment, the air curtain generator 240 includes two air inlets 242. The two air inlets 242 are disposed on two sides of the spray outlet pipe 221. An inlet 242 may be provided on the flange, and the carrier gas enters the pre-growth tube 210 through the inlet 242, and forms a uniformly distributed and uniformly directed gas flow through the 1-4 gas curtain forming plates 241.
In one embodiment, the total flow rate of carrier gas input by the gas curtain generator 240 is controlled within the range of 1-20L/min.
After the raw material gas enters the pre-growth tube 210, the catalyst precursor needs to be decomposed first to obtain the catalyst iron atoms. The promoter then needs to be decomposed, releasing sulfur atoms, which can interact with the catalyst particle clusters to control the size distribution of the catalyst particles and thus the diameter of the carbon nanotube structures. Finally decomposing the carbon source and growing the carbon nano-tube on the catalyst particles. Wherein the temperature ranges for catalyst precursor decomposition, promoter decomposition, and carbon source decomposition are all different. In order to ensure the smooth progress of the reaction and the quality of the carbon nanotubes, the reaction temperatures in different regions in the pre-growth tube 210 and the growth tube 230 need to be refined to form gradient temperatures.
In one embodiment, the reaction including decomposition of the catalyst precursor and decomposition of the promoter is performed in the pre-growth tube 210, and decomposition of the carbon source and growth of the carbon nanotubes are performed in the growth tube 230. Thus, the temperature within the pre-growth tube 210 and the temperature within the growth tube 230 are different.
In one embodiment, the temperature within the pre-growth tube 210 is in the range of 200-950 ℃. The temperature range in the growth tube 230 is 1100-1600 ℃.
In one embodiment, as shown in fig. 2, the pre-growth tube 210 and the growth tube 230 are connected by a first insulating member 250 having a tubular shape.
The first thermal insulation member 250 serves to reduce mutual interference of temperatures between the pre-growth tube 210 and the growth tube 230. To ensure the decomposition of the carbon source, the temperature in the growth tube 230 needs to reach 1100-1600 ℃. The temperature required for decomposing the accelerant is generally 700 ℃ and 950 ℃ at the rear end of the pre-growth tube. There is a temperature differential between pre-growth tube 210 and growth tube 230. The relative independence of the temperatures of the respective regions is ensured, the relevant interference is avoided, and the pre-growth pipe 210 and the growth pipe 230 are separated by a certain distance and connected through a first heat insulating member 250 having a heat insulating function, so that the interference between the different regions is reduced.
In one embodiment, the first insulating member 250 is composed of an insulating material, and the pipe diameter of the first insulating member 250 is the same as that of the growth pipe 230 and the pre-growth pipe 210. The first insulating member 250 is hermetically connected with the growth tube 230 and the pre-growth tube 210, respectively.
In one embodiment, the first insulating member 250 is composed of a high temperature insulating material, which may be one of high alumina brick, corundum, magnesia brick, and high temperature refractory fiber.
In one embodiment, the first insulating member 250 has a tube diameter of 50-500mm and a length of 50-200 mm.
As shown in fig. 2, in one embodiment the pre-growth tube 210 is segmented, comprising at least a first pre-growth segment 211 and a second pre-growth segment 212. The first pre-growth section 211 is a portion near the front end and the second pre-growth section 212 is a portion near the back end. The first pre-growth stage 211 is a reaction zone where the catalyst precursor is decomposed, and the second pre-growth stage 212 is a reaction zone where the promoter is decomposed. The temperature in the first pre-growth section 211 is different from the temperature in the second pre-growth section 212.
In one embodiment, the temperature in the first pre-growth section 211 is 200 ℃ to 300 ℃. The temperature within the second pre-growth section 212 is 700 and 950 degrees celsius.
In one embodiment, the first pre-growth section 211 and the second pre-growth section 212 are connected by a second thermal insulation member 260. For reducing temperature interference between the first pre-growth section 211 and the second pre-growth section 212.
In one embodiment, the second thermal insulator 260 is comprised of a thermally insulating material. The pipe diameter of the second heat-insulating member 260 is the same as the pipe diameters of the first and second pre-growth sections 211 and 212. The two sides of the second heat-insulating member 260 are hermetically connected with the first pre-growth section 211 and the second pre-growth section 212 respectively.
In one embodiment, the second thermal insulation member 260 has a tube diameter of 50 to 500mm and a length of 50 to 200 mm.
As shown in fig. 2, the first pre-growth section 211, the second pre-growth section 212, and the outer side of the growth tube 230 are further provided with a first temperature controller 271, a second temperature controller 272, and a third temperature controller 273, respectively.
The first temperature controller 271 is configured to control the temperature in the first pre-growth section 211, control the temperature in the first pre-growth section 211 within a certain range, and ensure that the temperature in the first pre-growth section 211 is uniformly distributed.
In one embodiment, the first temperature controller 271 comprises a first heating device and a first cooling device. The first temperature controller 271 may further comprise several temperature sensors capable of detecting temperature values within the first pre-growth section 211.
The second temperature controller 272 is used for controlling the temperature in the second pre-growth section 212, controlling the temperature in the second pre-growth section 212 within a certain value range, and ensuring that the temperature distribution in the second pre-growth section 212 is uniform. In one embodiment, the second temperature controller 272 includes a second heating device and a second cooling device. The second temperature controller 272 may also include a number of temperature sensors capable of detecting temperature values within the second pre-growth section 212.
The third temperature controller 273 is used to control the temperature inside the growth tube 230, control the temperature inside the growth tube 230 within a certain range of values, and ensure uniform temperature distribution inside the growth tube 230. In one embodiment, the third temperature controller 273 includes a second heating device and a second cooling device. The third temperature controller 273 may also include a number of temperature sensors capable of detecting temperature values within the growth tube 230.
In one embodiment, the first heating device, the second heating device and the third heating device may be steam heating, hot water heating, mineral oil heating, electromagnetic induction heating or resistance heating.
In one embodiment, the first cooling device, the second cooling device and the third cooling device may be in the form of refrigerant cooling, cooling water cooling, cooling oil cooling, or the like.
The invention thins the reaction region and divides the reaction region into a first pre-growth tube, a second pre-growth tube and a growth tube. A certain gap is arranged between every two sections, so that mutual interference is reduced. Through sectional management, the temperature precision is improved, fine control of the process is facilitated, and the quality of the carbon nano tube is improved.
In one embodiment, the inner wall of the growth tube 230 is provided with an anti-sticking coating for preventing the carbon nanomaterial from adhering to the inner wall of the growth tube.
In one embodiment, the release coating is zirconium oxide or zinc oxide.
In the industrial continuous production of carbon nanotubes, the failure to continue the production due to the breakage of carbon nanotubes is the most important factor that hinders the continuous production of carbon nanotubes. Among them, the adhesion and sticking of the carbon nanotubes to the tube wall are the main cause of the breakage of the carbon nanotubes. The high-temperature resistant anti-sticking coating of zirconium oxide or zinc oxide is prepared on the inner wall of the growth tube 230, which is beneficial to reducing the adhesion and sticking of the carbon nanotubes on the tube wall.
In one embodiment, the release coating has an arithmetic mean deviation Ra of the surface roughness profile of 0.1 μm to 1 μm.
In one embodiment, the growth tube 230 is provided with vent holes for introducing carrier gas to form a gas protection layer on the inner wall surface, and the vent holes penetrate through the tube wall of the growth tube and are uniformly distributed. By arranging the protective gas at the inner wall close to the growth tube 230, the adhesion of the carbon nanotubes can be avoided, and the carbon nanotubes can be guided in the moving direction to assist the collection of the carbon nanotubes.
In one embodiment, the angle between the axial direction of the vent hole and the extension direction of the growth tube is less than 5 degrees. And enabling the carrier gas to form a gas protection layer on the surface of the inner wall.
In one embodiment, the carbon nanotube preparation system 200 may have a horizontal distribution structure. Namely, the atomizer 220, the pre-growth tube 210, and the growth tube 230 are placed in order horizontally.
In one embodiment, the carbon nanotube preparation system 200 can be a vertical distribution structure. Namely, the atomizer 220, the pre-growth tube 210, and the growth tube 230 are sequentially placed in a vertical direction. So that the air curtain formed by the air curtain generator 240 is distributed in parallel in the direction of gravity.
In one embodiment, the carbon nanotube preparation system 200 can be a vertical distribution structure. The carbon nanotube collection system 300 and the exhaust system 400 may be horizontal structures. To facilitate the collection of the carbon nanotubes.
It will be appreciated that in a horizontal configuration, the gas will be subject to gravity and it is difficult to ensure that the curtain of gas will maintain an absolute horizontal laminar flow in the horizontal direction. The carbon nanotube preparation system 200 is arranged to be vertical, so that the influence of gravity can be overcome, and the absolute laminar flow of the air curtain is ensured. And due to the action of gravity, the consistency of the directions of the air flows in the pre-growth pipe 210 and the growth pipe 230 is facilitated, and the stability of the air flow in the system can be greatly improved. This advantage is not comparable to a horizontal system.
In practical application, the vertical system can continuously produce for 15 hours, which is superior to the horizontal system (the horizontal system can continuously produce for about 5 hours generally).
The carbon nano tube film material obtained by the preparation system has the performance of reaching 5 multiplied by 10 of electric conductivity4-5×105S/m (measured by a four-probe resistivity tester) and tensile strength of 80-200MPa (measured by a nano-tensile tester).
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (16)
1. A carbon nanotube production system, comprising:
the pre-growth tube is used for the preliminary reaction of the raw materials before the carbon nano tube is generated; the pre-growth tube comprises a first pre-growth section and a second pre-growth section; the first pre-growth section is close to the front end of the pre-growth pipe, and the second pre-growth section is close to the rear end of the pre-growth pipe; the temperature in the first pre-growth section is 200-300 ℃, and the temperature in the second pre-growth section is 700-950 ℃;
the atomizer is used for atomizing the carbon nano tube raw material and then spraying the atomized carbon nano tube raw material into the pre-growth tube; the atomizer is arranged at the front end of the pre-growth pipe and provided with a spray output pipe, and the spray output pipe extends into the pre-growth pipe;
a growth tube for generating carbon nanotubes and performing continuous growth of the generated carbon nanotubes; the front end of the growth tube is hermetically connected with the rear end of the pre-growth tube; the temperature in the growth tube is 1100-1600 ℃;
the air curtain generator is used for forming an air curtain wrapping atomized air flow around the outlet of the spray output pipe, and the air curtain extends along the direction parallel to the extension direction of the pre-growth pipe; the air curtain generator is arranged in the pre-growth tube.
2. The carbon nanotube production system according to claim 1,
the air curtain generator comprises at least one air curtain forming plate, and a plurality of air holes are formed in the air curtain forming plate.
3. The carbon nanotube production system according to claim 2,
the air curtain forming plate is annular, and the spray output pipe is positioned at the central hollow-out part of the air curtain forming plate; the air holes are radially distributed on the air curtain forming plate.
4. The carbon nanotube production system according to claim 2 or 3,
the edge profile of the air curtain forming plate is matched with the inner wall of the pre-growth tube, and at least part of the air holes are located in the edge area of the air curtain forming plate so as to form air curtain flow tightly attached to the inner wall of the pre-growth tube.
5. The carbon nanotube production system according to claim 2 or 3,
the gas curtain generator also comprises at least one gas inlet used for inputting carrier gas into the pre-growth tube, and the gas inlet is positioned at the front end of the pre-growth tube.
6. The carbon nanotube production system according to any one of claims 1 to 3,
the pre-growing pipe is connected with the growing pipe through a tubular first heat insulation piece.
7. The carbon nanotube production system according to claim 1,
a first temperature controller is arranged outside the first pre-growth section, and a second temperature controller is arranged outside the second pre-growth section;
the first pre-growth section and the second pre-growth section are connected through a second heat insulation piece.
8. The carbon nanotube production system according to claim 7,
the first temperature controller comprises a first heating device and a first cooling device;
the second temperature controller includes a second heating device and a second cooling device.
9. The carbon nanotube production system according to any one of claims 1 to 3,
the inner wall of the growth tube is provided with an anti-sticking coating for preventing the carbon nano tube raw material from being attached to the inner wall of the growth tube.
10. The carbon nanotube production system according to claim 9,
the anti-sticking coating is zirconium oxide or zinc oxide.
11. The carbon nanotube production system according to any one of claims 1 to 3,
the growth tube is provided with vent holes for introducing carrier gas to enable the carrier gas to form a gas protection layer on the inner wall surface of the growth tube, and the vent holes penetrate through the tube wall of the growth tube and are uniformly distributed.
12. The carbon nanotube production system according to claim 11,
and an included angle between the axial direction of the vent hole and the extending direction of the growth tube is less than 5 degrees.
13. The carbon nanotube production system according to any one of claims 1 to 3,
the atomizer comprises an ultrasonic atomizing nozzle and an ultrasonic controller, wherein the ultrasonic atomizing nozzle is used for uniformly mixing and atomizing the raw materials and then spraying the raw materials, and the ultrasonic controller is used for adjusting the numerical value of ultrasonic waves.
14. The carbon nanotube production system according to any one of claims 1 to 3,
the carbon nanotube preparation system is vertical or horizontal.
15. The carbon nanotube production system according to claim 14,
the pre-growth pipe and the growth pipe are vertically arranged, and the atomizer is arranged along the pre-growth pipe and the growth pipe in a vertical direction.
16. The carbon nanotube production system according to claim 15,
the air curtains are distributed in parallel along the gravity direction.
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| CN114477143B (en) * | 2022-03-25 | 2023-09-22 | 江西省纳米技术研究院 | Reaction furnace tube of carbon nano tube material and growth device and method |
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