Continuous preparation method of super-long carbon nanotubes

Abstract

The invention belongs to the technical field of nano material preparation, and particularly relates to a continuous preparation method of an ultra-long carbon nano tube. The invention provides a continuous preparation method of an ultra-long carbon nanotube, which comprises the following steps: (1) introducing inert gas into a reactor, and heating to a reaction temperature; (2) introducing a mixed gas of a carbon source gas, hydrogen, an inert gas and water vapor into the reactor, and injecting a multi-component catalyst at the same time for growth of an ultra-long carbon nanotube; (3) after the growth is finished, cooling the reactor; wherein the reactor is a straight pipe reactor with the length of 5-110 m and the pipe diameter of 0.05-10 m or a spiral tubular reactor with the length of 2-50 m, the number of turns of 5-500, the small diameter of 0.04-0.5 m and the large diameter of 0.5-2 m, a feeding pipe with the length of 0.1-0.5 m and the pipe diameter of 0.01-0.1 m is arranged at a feeding port of the reactor, and no substrate is arranged in the reactor. According to the method, the super-long carbon nanotubes directly grow in the three-dimensional space in the reactor, and the yield is improved by at least ten millions of times compared with the yield reported in the past.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to a continuous preparation method for ultralong carbon nanotubes. Background Technology

[0002] Carbon nanotubes are considered one of the materials with the best known mechanical properties. Their density is only one-sixth that of steel, but their Young's modulus exceeds 1 TPa (1 TPa = 1 × 10⁻⁶). 12 Pa), tensile strength exceeding 100 GPa (1 GPa = 1 × 10 Pa), 9 With a tensile strength exceeding that of carbon fiber T1000 (approximately 6.37 GPa), it has more than 15 times the tensile strength of carbon fiber T1000 (approximately 6.37 GPa), and has great application prospects in fields such as high-strength fibers, bulletproof vests, and aerospace.

[0003] Based on their morphology, carbon nanotubes can be divided into three types (such as...). Figure 1 (As shown): Aggregate carbon nanotubes, vertically arrayed carbon nanotubes, and horizontally arrayed carbon nanotubes. Aggregate and vertically arrayed carbon nanotubes are generally in the millimeter range in length and have many defects. Their mechanical, electrical, and thermal properties are far lower than theoretical values, failing to reflect and fully utilize the excellent intrinsic properties of carbon nanotubes. In contrast, horizontally arrayed carbon nanotubes follow a free growth mechanism and can reach lengths of centimeters or even decimeters and above, hence they are also called "ultra-long carbon nanotubes".

[0004] Although aggregated and vertically arrayed carbon nanotubes have already achieved mass production at the thousand-ton level annually, the lengths of these nanotubes are all in the millimeter or even micrometer range, and most contain numerous defects, making them unsuitable for manufacturing high-strength fibers. The tensile strength of current carbon nanotube fibers is only 0.5–11.5 GPa, far below the theoretical strength of carbon nanotubes (>100 GPa). This is because these short carbon nanotubes are mainly randomly entangled and twisted into bundles by van der Waals forces, making them highly susceptible to relative sliding and breakage under tension, failing to fully utilize the theoretical strength of a single carbon nanotube. In contrast, ultralong carbon nanotubes, due to their macroscopic length and perfect structure, have a significant advantage in preparing ultra-strong carbon nanotube fibers.

[0005] As a one-dimensional mechanical material, the aspect ratio of carbon nanotubes is an important indicator of their mechanical application value; the longer they are, the more pronounced their advantages as ultra-strong fibers. Ultra-long carbon nanotubes possess a huge aspect ratio (10... 6 ~10 9With low defect density, carbon nanotubes best demonstrate their intrinsic superior properties and have broad application prospects in cutting-edge fields such as microelectronics, high-strength fibers, and aerospace. A prerequisite for realizing the application of ultralong carbon nanotubes is the large-scale production of carbon nanotubes with macroscopic lengths exceeding centimeters. Faced with the enormous demand for high-performance carbon nanotubes in cutting-edge fields such as high-strength fibers and aerospace, how to achieve the controllable growth and large-scale production of carbon nanotubes with macroscopic lengths exceeding centimeters is one of the most significant challenges facing the field of carbon nanotube research. The root cause of the failure to achieve the growth and large-scale production of ultralong carbon nanotubes with macroscopic lengths exceeding centimeters lies in the still insufficient and incomplete understanding of their growth mechanisms and methodologies. The main methods for preparing carbon nanotubes include arc ablation, laser ablation, and chemical vapor deposition (CVD). Among these, CVD has been widely used due to its advantages such as easy parameter control, wide applicability, and ease of scale-up, making it the main method for preparing macroscopically long carbon nanotubes. Based on current understanding, the growth of ultralong carbon nanotubes mainly follows two mechanisms (such as...). Figure 2 (As shown): Top-end growth mechanism and bottom-end growth mechanism. Generally, ultralong carbon nanotubes prepared on substrates such as silicon wafers that do not have a clear lattice structure follow the top-end growth mechanism. During the growth process, the carbon nanotubes float in the gas flow, while the catalyst remains at the top of the carbon nanotube and grows forward along the gas flow. In traditional methods for preparing macroscopically long carbon nanotubes with relatively perfect structures, the catalyst is generally applied to the silicon wafer substrate using micro-contact printing. In this process, on the one hand, only a very small portion of the carbon nanotubes can float and escape the interference of the substrate, growing forward under the impetus of the gas flow, and following a relatively free top-end growth mode to grow into macroscopically long carbon nanotubes with perfect structures; on the other hand, the amount of catalyst used in a single growth is also limited by the size of the substrate, which makes it difficult to achieve a macroscopic level of carbon nanotube yield. Therefore, the array density of macroscopically long carbon nanotubes grown by traditional methods is generally only a few nanotubes per millimeter, far from meeting the requirements for the mass production of macroscopically long carbon nanotubes. Ultralong carbon nanotubes prepared on substrates with distinct lattice structures and strong interactions, such as quartz, follow a bottom-growth mechanism. In this mechanism, the catalyst is fixed to the substrate during growth, while the carbon nanotubes grow along the lattice guide, closely adhering to the substrate. However, ultralong carbon nanotubes prepared using this bottom-growth mechanism are easily disturbed due to their close adherence to the substrate, thus limiting their length to the centimeter level and restricting their mass production to a single layer. In contrast, tip-growth offers significant advantages. Although the array density of ultralong carbon nanotubes currently grown using this tip-growth mechanism is not high, a substantial increase in density is expected once the limitations of their preparation methods are overcome. Therefore, further research is needed into the tip-growth mechanism of ultralong carbon nanotubes to achieve significant increases in both length and array density, thereby enabling the controllable growth and mass production of macroscopically long carbon nanotubes.

[0006] Furthermore, facing the significant demand for ultra-strong materials in cutting-edge fields such as defense and aerospace, my country has lost its international market and competitive advantage in the field of high-performance carbon fibers (such as T1000), with related technologies and markets firmly controlled by countries like Japan. In contrast, my country started its research on carbon nanotubes earlier and remains internationally leading in the controllable fabrication of ultra-long carbon nanotubes. Therefore, achieving the controllable growth and mass production of macroscopically long carbon nanotubes is of great strategic significance for realizing their practical industrial applications and the preparation of ultra-strong carbon nanotube fibers, changing my country's long-standing dependence on others in high-performance fibers, and seizing the commanding heights in the preparation of high-quality carbon nanotubes and their applications in cutting-edge fields such as aerospace. Summary of the Invention

[0007] This invention is based on the inventor's discoveries and understanding of the following facts and problems: Although significant progress has been made in the research of ultralong carbon nanotubes over the past decade, including the development of various directional growth methods such as lattice manipulation, electric field manipulation, and gas flow manipulation; the length of these nanotubes has increased from a few micrometers initially to 65 centimeters reported in 2019; the array density of ultralong carbon nanotubes fabricated on silicon substrates has increased from one nanometer per millimeter to hundreds per millimeter, and the array density of ultralong carbon nanotubes fabricated on quartz substrates has increased to 130 nanometers per micrometer; the selectivity of semiconductor carbon nanotubes has reached 97.6%, and the selectivity of metallic carbon nanotubes has reached 80%; Professors Li Yan and Zhang Jin of Peking University made breakthroughs in the highly selective preparation of specific chiral carbon nanotubes in 2014 and 2017, respectively, with the selectivity of (12,6) type single-walled tubes reaching over 92%. However, these advances have not solved the problem of the controllable growth and mass production of carbon nanotubes with macroscopic lengths of centimeters and above.

[0008] Currently, the density of ultralong carbon nanotube arrays prepared on both silicon wafers and quartz substrates is still far lower than that of agglomerated and vertically arrayed carbon nanotubes. On the one hand, their lengths are mostly still in the centimeter range; on the other hand, their production volume is far from meeting the needs of practical applications.

[0009] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a method for the mass production of ultralong nanotubes. This method eliminates the need for any high-temperature resistant flat substrate, allowing ultralong carbon nanotubes to grow directly in the three-dimensional space within a reactor. This increases the yield of ultralong carbon nanotubes by at least ten million times compared to previously reported yields, meeting the requirements for mass production. Furthermore, the ultralong carbon nanotubes produced using this method can reach lengths in the centimeter or even meter range, and each individual nanotube possesses characteristics such as a relatively perfect structure, small diameter, and low wall density.

[0010] A continuous preparation method for ultralong carbon nanotubes according to an embodiment of the present invention includes the following steps: (1) Inert gas is introduced into the reactor and the temperature is raised to the reaction temperature; (2) A mixture of carbon source gas, hydrogen, inert gas and water vapor is introduced into the reactor, and a multi-component catalyst is injected at the same time to start the growth of ultra-long carbon nanotubes. (3) After the growth of the ultra-long carbon nanotubes described in step (2) is completed, the reactor is cooled; The reactor is a straight tube reactor with a length of 5-110 m and a diameter of 0.05-10 m, or a spiral tube reactor with a length of 2-50 m, a number of turns of 5-500, a small diameter of 0.04-0.5 m, and a large diameter of 0.5-2 m; the feed inlet of the reactor is provided with a feed pipe with a length of 0.1-0.5 m and a diameter of 0.01-0.1 m, and the reactor does not have a base.

[0011] The advantages and technical effects of the continuous preparation method of ultra-long carbon nanotubes in this invention are as follows: 1. The method of this invention directly injects the catalyst into the reactor, eliminating the need for any high-temperature resistant flat substrate. Ultra-long carbon nanotubes can grow in the three-dimensional space of the reactor, increasing the yield of ultra-long carbon nanotubes by at least a thousand times compared to previously reported yields, thus meeting the requirements for large-scale preparation; 2. By adjusting the preparation conditions, the growth rate of ultra-long carbon nanotubes reaches over 2 mm / min, improving production efficiency; 3. Through the structural design of the reactor, the effective growth time of carbon nanotubes in the reactor is significantly increased, thereby maintaining large-scale carbon nanotube preparation while significantly increasing the average length of carbon nanotubes. The feed pipe at the reactor inlet allows for direct injection of materials into the high-temperature zone, improving production efficiency; 4. The method of this invention produces ultra-long carbon nanotubes with lengths reaching centimeters or even meters, and each nanotube possesses relatively perfect structure, small diameter, and low wall density; 5. The method of this invention is simple, efficient, and easy to operate, facilitating its widespread application in industrial production.

[0012] In some embodiments, in step (1), the flow rate of the inert gas is 0.01~100000 mL / min; and / or, the reaction temperature is 500~2000 ℃; preferably, the flow rate of the inert gas is 500~2000 mL / min; and / or, the reaction temperature is 980~1300 ℃.

[0013] In some embodiments, in step (2), the method of injecting the multi-component catalyst is to inject the multi-component catalyst solution into the reactor using an injection pump or to place the multi-component catalyst solid powder in a constant temperature chamber for sublimation, and to use a carrier gas to carry the sublimated multi-component catalyst into the reactor.

[0014] In some embodiments, the concentration of the multi-component catalyst solution is 0.1~80 wt%, and the injection flow rate of the multi-component catalyst solution is 0.01~300000 μL / min; preferably, the concentration of the multi-component catalyst solution is 0.1~5 wt%, and the injection flow rate of the multi-component catalyst solution is 100~600 μL / min. And / or, the solvent of the multi-component catalyst solution includes at least one selected from methanol, ethanol, isopropanol, n-butanol, acetone, benzene, toluene, ethylbenzene, xylene, n-hexane, and cyclohexane.

[0015] In some embodiments, the sublimation temperature of the multi-component catalyst is 50~1500 °C; the flow rate of the carrier gas is 1~5000 mL / min; preferably, the sublimation temperature of the multi-component catalyst is 50~400 °C; and the flow rate of the carrier gas is 50~200 mL / min.

[0016] In some embodiments, the multi-component catalyst comprises at least two of ferric chloride, copper chloride, nickel chloride, sulfur powder, cobalt chloride, ferrocene, ferric acetylacetone, copper acetate, copper acetylacetone, ferric nitrate, thiophene, and nickel acetylacetone.

[0017] In some embodiments, in step (2), the proportion of carbon source gas in the mixed gas is 0.001~60 vol%, the proportion of hydrogen is 1~90 vol%, the proportion of inert gas is 20~90 vol%, the concentration of water vapor is 1~100000 ppm, and the total flow rate of the mixed gas is 500~5000 mL / min; And / or, the growth time of the ultralong carbon nanotubes is 30~50000 min; And / or, the carbon source gas includes at least one of methane, ethane, ethylene, acetylene, methanol vapor, ethanol vapor, isopropanol vapor, n-butanol vapor, acetone vapor, carbon monoxide, and toluene vapor; And / or, in step (3), the reactor is cooled under the protection of an inert gas, and the total flow rate of the inert gas is 10~10000 mL / min; preferably, the total flow rate of the inert gas is 500~2000 mL / min.

[0018] In some embodiments, the straight tube reactor is a quartz straight tube or a corundum straight tube, and the straight tube reactor is heated by a horizontal tube furnace with a length of 5 to 100 m.

[0019] In some embodiments, the spiral tubular reactor is a spiral quartz tube or corundum tube, and the spiral tubular reactor is heated by a heating furnace with a length of 1.5~45 m and an inner diameter of 0.5~10 m; preferably, the spiral tubular reactor tube has a length of 15~30 m, a small diameter of 0.04~0.06 m, a large diameter of 0.5~1 m, and a number of turns of 50~100, and the heating furnace has a length of 14~29 m and an inner diameter of 0.6~1.2 m.

[0020] This invention also provides an ultralong carbon nanotube, which is prepared using the method described above.

[0021] The advantages and technical effects of the ultra-long carbon nanotubes in the embodiments of the present invention are as follows: 1. In the embodiments of the present invention, the length of the ultra-long carbon nanotubes can reach centimeters or even meters. A single carbon nanotube has a relatively perfect structure, and the tube diameter is small and the number of tube walls is small; 2. In the embodiments of the present invention, the ultra-long carbon nanotubes have high performance and can meet the application requirements of fields such as ultra-strong fibers, transparent conductive films, flexible wearable devices, and carbon-based chips. Attached Figure Description

[0022] Figure 1 These are three different carbon nanotube morphologies; Figure 2 This is a schematic diagram of two different growth mechanisms of ultralong carbon nanotubes; Figure 3 These are schematic diagrams of the two reactors and their supporting heating furnaces used in Examples 1 and 2, where A represents Example 1 and B represents Example 2. Figure 4 These are scanning electron microscope images of the ultralong carbon nanotubes prepared in Example 1; Figure 5 This is a transmission electron microscope image of the ultralong carbon nanotubes prepared in Example 1; Figure 6 These are transmission electron microscope images of the multi-component catalyst prepared in Example 1; Figure 7 This is the Raman spectrum of the ultralong carbon nanotubes prepared in Example 1. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] A continuous preparation method for ultralong carbon nanotubes according to an embodiment of the present invention includes the following steps: (1) Inert gas is introduced into the reactor and the temperature is raised to the reaction temperature; (2) A mixture of carbon source gas, hydrogen, inert gas and water vapor is introduced into the reactor, and a multi-component catalyst is injected at the same time to grow ultra-long carbon nanotubes. (3) After the growth of the ultra-long carbon nanotubes described in step (2) is completed, the reactor is cooled; The reactor is a straight tube reactor with a length of 5-110 m and a diameter of 0.05-10 m, or a spiral tube reactor with a length of 2-50 m, a number of turns of 5-500, a small diameter of 0.04-0.5 m, and a large diameter of 0.5-2 m; the feed inlet of the reactor is provided with a feed pipe with a length of 0.1-0.5 m and a diameter of 0.01-0.1 m, and the reactor does not have a base.

[0025] The continuous preparation method for ultralong carbon nanotubes in this invention involves directly injecting the catalyst into the reactor, eliminating the need for any high-temperature resistant flat substrate. The ultralong carbon nanotubes can grow within the three-dimensional space of the reactor, increasing the yield by at least a thousand times compared to previously reported yields, thus meeting the requirements for large-scale production. Adjustments to the preparation conditions achieve a growth rate exceeding 2 mm / min, improving production efficiency. The reactor's structural design significantly extends the effective growth time of carbon nanotubes within the reactor, thereby maintaining large-scale production while substantially increasing the average length of the carbon nanotubes. A feed pipe at the reactor's inlet allows for direct injection of material into the high-temperature zone, further enhancing production efficiency. The resulting ultralong carbon nanotubes can reach lengths in the centimeter or even meter range, exhibiting relatively perfect structure, small diameter, and low wall density. The method is simple, efficient, and easy to operate, facilitating its widespread application in industrial production.

[0026] In some embodiments, preferably, in step (1), the flow rate of the inert gas is 0.01~100000 mL / min; and / or, the reaction temperature is 500~2000 °C; preferably, the flow rate of the inert gas is 500~2000 mL / min; and / or, the reaction temperature is 980~1300 °C. More preferably, the inert gas contains at least one of nitrogen, argon, and helium.

[0027] In this embodiment of the invention, an inert gas is introduced into the reactor before the preparation of ultra-long carbon nanotubes to remove the air in the reactor, thereby avoiding any impact on the preparation of ultra-long carbon nanotubes and ensuring that the prepared carbon nanotubes have a low defect density.

[0028] In some embodiments, preferably, in step (2), the method of injecting the multi-component catalyst is to inject the multi-component catalyst solution into the reactor using an injection pump or to place the multi-component catalyst solid powder in a constant temperature chamber for sublimation, and to use a carrier gas to carry the sublimated multi-component catalyst into the reactor.

[0029] In some embodiments, preferably, the concentration of the multi-component catalyst solution is 0.1~80 wt%, and the injection flow rate of the multi-component catalyst solution is 0.01~300000 μL / min; more preferably, the concentration of the multi-component catalyst solution is 0.1~5 wt%, and the injection flow rate of the multi-component catalyst solution is 100~600 μL / min. And / or, the solvent of the multi-component catalyst solution includes at least one selected from methanol, ethanol, isopropanol, n-butanol, acetone, benzene, toluene, ethylbenzene, xylene, n-hexane, and cyclohexane.

[0030] In some embodiments, preferably, the sublimation temperature of the multi-component catalyst is 50~1500 °C; the flow rate of the carrier gas is 1~5000 mL / min; more preferably, the sublimation temperature of the multi-component catalyst is 50~400 °C; the flow rate of the carrier gas is 50~200 mL / min.

[0031] In this embodiment of the invention, these two methods are used to inject multi-component catalysts into the reactor, eliminating the dependence on a high-temperature resistant and flat substrate during the preparation of ultra-long carbon nanotubes. This facilitates the controllable growth and mass production of ultra-long carbon nanotubes and enables controllable feeding of multi-component catalysts. By further optimizing the feeding parameters of the multi-component catalyst solution method and the multi-component catalyst powder method, it is ensured that the multi-component catalyst is uniformly distributed in the reactor, meeting the growth requirements of ultra-long carbon nanotubes in the reactor.

[0032] In some embodiments, preferably, the multi-component catalyst comprises at least two of ferric chloride, copper chloride, nickel chloride, sulfur powder, cobalt chloride, ferrocene, ferric acetylacetone, copper acetate, copper acetylacetone, ferric nitrate, thiophene, and nickel acetylacetone.

[0033] In this embodiment of the invention, a multi-component catalyst is used. The multi-component catalyst can adjust the carbon solubility and melting point of the catalyst to achieve the best carbon nanotube catalytic growth effect. By using a multi-component catalyst, the yield of carbon nanotubes is greatly improved.

[0034] In some embodiments, preferably, in step (2), the proportion of carbon source gas in the mixed gas is 0.001~60 vol%, the proportion of hydrogen is 1~90 vol%, the proportion of inert gas is 20~90 vol%, the concentration of water vapor is 1~100000 ppm; and the total flow rate of the mixed gas is 500~5000 mL / min. And / or, the growth time of the ultralong carbon nanotubes is 30~50000 min; And / or, the carbon source gas includes at least one of methane, ethane, ethylene, acetylene, methanol vapor, ethanol vapor, isopropanol vapor, n-butanol vapor, acetone vapor, carbon monoxide, and toluene vapor; the inert gas includes at least one of nitrogen, argon, and helium. And / or, in step (3), the reactor is cooled under the protection of an inert gas, the total flow rate of which is 10~10000 mL / min; more preferably, the total flow rate of which is 500~2000 mL / min. Even more preferably, the inert gas includes at least one of nitrogen, argon, and helium.

[0035] In this embodiment of the invention, the composition of the mixed gas is optimized to maintain the carbon source content within a suitable range to meet the growth requirements of ultra-long carbon nanotubes. The introduced inert gas keeps the reactor under protection, preventing other impurity gases from affecting the growth of ultra-long carbon nanotubes. The introduced hydrogen gas provides a reducing atmosphere for the growth of ultra-long carbon nanotubes, ensuring their normal growth. The introduced water vapor can etch carbon deposits on the catalyst, extending the catalyst's lifespan. After the ultra-long carbon nanotubes grow, the reactor is subjected to a relatively high temperature. Direct cooling would cause the reactor's inner wall to easily react with oxygen and water vapor in the air, leading to corrosion. Under the protection of the inert gas, the reactor cools slowly, preventing corrosion and extending its service life.

[0036] In some embodiments, preferably, the straight tube reactor is a quartz straight tube or a corundum straight tube, and the straight tube reactor is heated by a horizontal tube furnace with a length of 5 to 100 m.

[0037] In some embodiments, preferably, the spiral tubular reactor is a spiral quartz tube or corundum tube, and the spiral tubular reactor is heated by a heating furnace with a length of 1.5~45 m and an inner diameter of 0.5~10 m; preferably, the length of the spiral tubular reactor tube is 15~30 m, the small diameter is 0.04~0.06 m, the large diameter is 0.5~1 m, and the number of turns is 50~100, and the length of the heating furnace is 14~29 m and the inner diameter is 0.6~1.2 m.

[0038] In this embodiment of the invention, the reactor is designed in a spiral shape, which can reduce the space volume of the equipment and improve the utilization efficiency of the production plant.

[0039] This invention also provides an ultralong carbon nanotube, which is prepared using the method described above.

[0040] The ultra-long carbon nanotubes of this invention can reach lengths of centimeters or even meters. Each carbon nanotube has a relatively perfect structure, with a small diameter and few tube walls. The ultra-long carbon nanotubes have high performance and can meet the application requirements of fields such as ultra-strong fibers, transparent conductive films, flexible wearable devices, and carbon-based chips.

[0041] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0042] Example 1 (1) Adopting such Figure 3 As shown in Figure A, an ultra-long quartz tube with a diameter of 200 mm and a length of 5 m is used as the reactor. The reactor inlet is set with a feed pipe with a length of 0.3 m and a diameter of 10 mm. A large tubular furnace with a length of 6 m is used as the heating furnace. (2) Prepare a 0.1 wt% ferric chloride and 0.2 wt% chromium acetylacetonate ethanol mixture solution, draw the ethanol solution with a syringe and install it on the injection pump, and connect the liquid outlet of the syringe to the reactor; (3) The temperature of the reactor was slowly increased to 980 °C, and argon was introduced into the reactor at a flow rate of 1000 mL / min. When the temperature stabilized at 980 °C, methane, hydrogen, argon and water vapor with a concentration of 300 ppm were introduced, with a total flow rate of 2000 mL / min. The proportion of methane was 2 vol%, the proportion of hydrogen was 58 vol%, and the proportion of argon was 40 vol%. At the same time, the injection pump was turned on and an ethanol mixture solution was introduced at a flow rate of 200 μL / min to grow ultralong carbon nanotubes for 120 min. (4) After growth, the reactor was cooled under the protection of argon gas at a flow rate of 1000 mL / min. After cooling to room temperature, the reactor was opened and the ultra-long carbon nanotubes inside the reactor were removed.

[0043] The ultralong carbon nanotubes prepared in this embodiment have a length of 10 cm, a diameter of 1-5 nm per nanotube, a wall number of 1-3, a yield of 5 g, and a yield rate of 40%.

[0044] The ultralong carbon nanotubes prepared in the embodiments of this invention were tested using scanning electron microscopy under the following conditions: accelerating voltage 1.5 kV, beam current 10 μA. The results are as follows: Figure 4As shown, Figure 4 Images A and B in the middle are scanning electron microscope images of macroscopic ultra-long carbon nanotubes at different magnifications; Figure 4 Figure C shows the ultralong carbon nanotubes transferred onto a flat silicon wafer. As can be seen from the figure, the ultralong carbon nanotubes prepared in this embodiment of the invention have a smooth and flat surface with almost no defects.

[0045] The ultralong carbon nanotubes prepared in the embodiments of this invention were tested using transmission electron microscopy under the following conditions: accelerating voltage 120 kV; the results are as follows. Figure 5 As shown in the figure, the ultra-long carbon nanotubes prepared in the embodiments of the present invention are mainly single-walled carbon nanotubes, double-walled carbon nanotubes and triple-walled carbon nanotubes, and the diameter of the ultra-long carbon nanotubes is 1~3 nm.

[0046] The multi-component catalyst and ultralong carbon nanotube mixture prepared in the embodiments of the present invention were tested using transmission electron microscopy. The test conditions were: accelerating voltage 120 kV; the results are as follows. Figure 6 As shown in the figure, it can be seen that the components in the multi-component catalyst prepared in the embodiment of the present invention exhibit a highly uniform dispersion state.

[0047] The ultralong carbon nanotubes prepared in the embodiments of this invention were tested using Raman spectroscopy under the following conditions: 633 nm laser; the results are as follows. Figure 7 As shown in the figure, the ultralong carbon nanotubes prepared in the embodiment of the present invention have a perfect structure, with almost no D peaks representing the degree of defects.

[0048] Example 2 (1) Adopting such Figure 3 As shown in Figure B, a spiral hollow quartz tube with a large diameter of 1 m, a small diameter of 50 mm, a total length of 15 m, and 50 turns is used as the reactor. The reactor inlet is equipped with a feed pipe with a length of 0.1 m and a diameter of 15 mm. A large heating furnace with a length of 4.5 m and an inner cavity diameter of 1.1 m is also used. (2) Place iron acetylacetone powder and nickel acetylacetone powder in two constant temperature chambers at 100 °C and connect them to the reactor; (3) The temperature of the reactor is slowly increased to 1050 °C, and argon is introduced into the reactor at a flow rate of 500 mL / min. When the temperature stabilizes at 1050 °C, ethylene, hydrogen, argon and water vapor with a concentration of 500 ppm are introduced, with a total flow rate of 1800 mL / min. The proportion of ethylene is 5 vol%, the proportion of hydrogen is 45 vol%, and the proportion of argon is 50 vol%. At the same time, argon is used as a carrier gas and introduced into the constant temperature chamber at a flow rate of 200 mL / min to carry the sublimation gas of iron acetylacetone and nickel acetylacetone into the reactor for the growth of ultra-long carbon nanotubes. The growth time is 600 min. (4) After growth, the reactor was cooled under the protection of argon gas at a flow rate of 500 mL / min. After cooling to room temperature, the reactor was opened and the ultra-long carbon nanotubes inside the reactor were removed.

[0049] The ultralong carbon nanotubes prepared in this embodiment have a length of 15 cm, a diameter of 1-5 nm per nanotube, a wall number of 1-3, a yield of 20 g, and a yield rate of 35%.

[0050] Example 3 (1) A spiral hollow quartz tube with a large diameter of 1.5 m, a small diameter of 40 mm, a total length of 30 m, and 100 turns is used as the reactor. The reactor inlet is set with a feed pipe with a length of 0.2 m and a diameter of 10 mm, and a large heating furnace with a length of 29 m and an inner cavity diameter of 1.6 m is used. (2) Prepare a ethanol mixture of 1.6 wt% copper chloride and 2 wt% ferric chloride. Draw the ethanol mixture into a syringe and install it on the syringe pump. Connect the liquid outlet of the syringe to the reactor. (3) The temperature of the reactor is slowly increased to 1000 °C, and nitrogen is introduced into the reactor at a flow rate of 1100 mL / min. When the temperature stabilizes at 1150 °C, methane, hydrogen, nitrogen and water vapor with a concentration of 1000 ppm are introduced, with a total flow rate of 3000 mL / min. The proportion of methane is 3 vol%, the proportion of hydrogen is 37 vol%, and the proportion of argon is 60 vol%. At the same time, the injection pump is turned on and an ethanol mixture solution is introduced at a flow rate of 100 μL / min to grow ultralong carbon nanotubes for a growth time of 1000 min. (4) After growth, the reactor was cooled under the protection of argon gas at a flow rate of 500 mL / min. After cooling to room temperature, the reactor was opened and the ultra-long carbon nanotubes inside the reactor were removed.

[0051] The ultralong carbon nanotubes prepared in this embodiment have a length of 20 cm, a diameter of 1-5 nm per nanotube, a wall number of 1-3, a yield of 35 g, and a yield rate of 39%.

[0052] Example 4 (1) An ultra-long quartz tube with an inner diameter of 300 mm and a length of 8 m is used as the reactor. The reactor inlet is equipped with a feed pipe with a length of 0.5 m and a diameter of 30 mm. A large horizontal tube furnace with a length of 6 meters is used as the heating furnace. (2) Prepare a 2.5 wt% ferrocene and 1.5 wt% copper acetate acetone mixture solution, draw the acetone mixture solution with a syringe and install it on the injection pump, and connect the liquid outlet of the syringe to the reactor. (3) The temperature of the reactor was slowly increased to 1100 °C, and argon was introduced into the reactor at a flow rate of 1500 mL / min. When the temperature stabilized at 1300 °C, ethane, hydrogen, argon and water vapor with a concentration of 1200 ppm were introduced, with a total flow rate of 3000 mL / min. The proportion of ethane was 7 vol%, the proportion of hydrogen was 33 vol%, and the proportion of argon was 60 vol%. At the same time, the injection pump was turned on and acetone mixed solution was introduced at a flow rate of 150 μL / min to grow ultralong carbon nanotubes for 100 min. (4) After growth, the reactor was cooled under the protection of argon gas at a flow rate of 1500 mL / min. After cooling to room temperature, the reactor was opened and the ultra-long carbon nanotubes inside the reactor were removed.

[0053] The ultralong carbon nanotubes prepared in this embodiment have a length of 30 cm, a diameter of 1-5 nm per nanotube, a wall number of 1-3, a yield of 10 g, and a yield rate of 33%.

[0054] Comparative Example 1 The preparation method of this comparative example is the same as that of Example 1, except that in step (2), a mixed solution of 0.1 wt% ferric chloride and 0.2 wt% chromium acetylacetonate in ethanol is spin-coated onto a silicon wafer substrate and placed in a reactor.

[0055] The ultralong carbon nanotubes prepared in this comparative example have a length of 1 μm, a diameter of 1-2 nm per nanotube, a wall number of 1-2, a carbon nanotube density of a few per millimeter on the substrate, and a yield of almost zero.

[0056] Comparative Example 2 The preparation method of this comparative example is the same as that of Example 1, except that step (2) is omitted, and in step (3), the quartz substrate is placed in the reactor and carbon source gas, hydrogen, argon and water vapor are injected into the reactor at the same time.

[0057] This comparative example was unable to prepare carbon nanotubes.

[0058] Comparative Example 3 The comparative example was prepared using the same method as Example 1, except that the reactor had an inner diameter of 10 mm and a length of 5 m.

[0059] The comparative reactor was clogged and could not grow to its full length normally.

[0060] Comparative Example 4 The comparative example was prepared using the same method as Example 1, except that the reactor had an inner diameter of 200 mm and a length of 1 m.

[0061] The ultralong carbon nanotubes prepared in this comparative example have a length of 2 cm, a diameter of 1-5 nm per nanotube, a wall number of 1-3, a yield of 5 mg, and a yield of 0.04%.

[0062] Comparative Example 5 The preparation method of this comparative example is the same as that of Example 1, except that no feed pipe is provided at the reactor inlet.

[0063] The ultralong carbon nanotubes prepared in this comparative example have a length of 1 cm, a diameter of 1-5 nm per nanotube, a wall number of 1-3, a yield of 1 g, and a yield of 8%.

[0064] Comparative Example 6 The method of this comparative example is the same as that of Example 1, except that in step (2), a 0.3 wt% ferric chloride ethanol solution is prepared as a catalyst.

[0065] The ultralong carbon nanotubes prepared in this comparative example have a length of 9 cm, a diameter of 1-5 nm per nanotube, a wall number of 1-3, a yield of 3 g, and a yield of 24%.

[0066] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0067] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A method for continuous production of ultralong carbon nanotubes, characterized by, The method comprises the following steps: (1) introducing inert gas into a reactor and heating to a reaction temperature; (2) introducing a mixed gas of a carbon source gas, hydrogen, inert gas and water vapor into the reactor, and injecting a multi-component catalyst to grow the super-long carbon nanotube; (3) after the growth of the super-long carbon nanotube in step (2) is completed, cooling the reactor; The reactor is a straight tube reactor with a length of 5-110 m and a pipe diameter of 0.05-10 m, or a spiral tube reactor with a length of 2-50 m, a number of turns of 5-500, a small diameter of 0.04-0.5 m and a large diameter of 0.5-2 m; the feeding port of the reactor is provided with a feeding pipe with a length of 0.1-0.5 m and a pipe diameter of 0.01-0.1 m, and no substrate is arranged in the reactor.

2. The method of claim 1, wherein the method is characterized by: In step (1), the flow rate of the inert gas is 0.01-100000 mL / min; and / or the reaction temperature is 500-2000 ℃; preferably, the flow rate of the inert gas is 500-2000 mL / min; and / or the reaction temperature is 980-1300 ℃.

3. The method of claim 1, wherein the carbon nanotubes are single-walled carbon nanotubes. In step (2), the method for injecting the multi-component catalyst is to inject a multi-component catalyst solution into the reactor by using a syringe pump or to sublimate a multi-component catalyst solid powder in a thermostat box and then to carry the sublimated multi-component catalyst into the reactor by using a carrier gas.

4. The method of claim 3, wherein the carbon nanotubes are grown in a continuous process. The concentration of the multi-component catalyst solution is 0.1-80 wt%, and the injection flow rate of the multi-component catalyst solution is 0.01-300000 μL / min; preferably, the concentration of the multi-component catalyst solution is 0.1-5 wt%, and the injection flow rate of the multi-component catalyst solution is 100-600 μL / min; The solvent of the multi-component catalyst solution comprises at least one of methanol, ethanol, isopropanol, n-butanol, acetone, benzene, toluene, ethylbenzene, xylene, n-hexane and cyclohexane.

5. The method of claim 3, wherein the carbon nanotubes are grown in a continuous process. The sublimation temperature of the multi-component catalyst is 50-1500 ℃, and the flow rate of the carrier gas is 1-5000 mL / min; preferably, the sublimation temperature of the multi-component catalyst is 50-400 ℃, and the flow rate of the carrier gas is 50-200 mL / min.

6. The method of claim 1 to 5, wherein The multi-component catalyst comprises at least two of iron trichloride, copper chloride, nickel chloride, sulfur powder, cobalt chloride, ferrocene, iron acetylacetone, copper acetate, copper acetylacetone, iron nitrate, thiophene and nickel acetylacetone.

7. The method of claim 1, wherein the carbon nanotubes are single-walled carbon nanotubes. In step (2), the proportion of the carbon source gas in the mixed gas is 0.001-60 vol%, the proportion of the hydrogen is 1-90 vol%, the proportion of the inert gas is 20-90 vol%, and the concentration of the water vapor is 1-100000 ppm; the total flow rate of the mixed gas is 500-5000 mL / min; And / or, the growth time of the super-long carbon nanotube is 30-50000 min. And / or, the carbon source gas comprises at least one of methane, ethane, ethylene, acetylene, methanol vapor, ethanol vapor, isopropanol vapor, n-butanol vapor, acetone vapor, carbon monoxide, toluene vapor; And / or, in the step (3), the reactor is cooled under protection of inert gas, and the total flow rate of the inert gas is 10-10000 mL / min; preferably, the total flow rate of the inert gas is 500-2000 mL / min.

8. The method of claim 1, wherein the method is characterized by: The straight tube reactor is a quartz straight tube or a corundum straight tube, and the straight tube reactor is heated by a horizontal tube furnace with a length of 5-100 m.

9. The method of claim 1, wherein the carbon nanotubes are single-walled carbon nanotubes. The spiral tube reactor is a spiral quartz tube or a spiral corundum tube, and the spiral tube reactor is heated by a heating furnace with a length of 1.5-45 m and an inner cavity diameter of 0.5-10 m; preferably, the length of the spiral tube reactor tube is 15-30 m, the small diameter is 0.04-0.06 m, the large diameter is 0.5-1 m, the number of turns is 50-100, the length of the heating furnace is 14-29 m, and the inner cavity diameter is 0.6-1.2 m.

10. An ultralong carbon nanotube, characterized by, The method is prepared by any one of claims 1-9. And / or, the carbon source gas comprises at least one of methane, ethane, ethylene, acetylene, methanol vapor, ethanol vapor, isopropanol vapor, n-butanol vapor, acetone vapor, carbon monoxide, toluene vapor; And / or, in the step (3), the reactor is cooled under protection of inert gas, and the total flow rate of the inert gas is 10-10000 mL / min; preferably, the total flow rate of the inert gas is 500-2000 mL / min. The straight tube reactor is a quartz straight tube or a corundum straight tube, and the straight tube reactor is heated by a horizontal tube furnace with a length of 5-100 m. The spiral tube reactor is a spiral quartz tube or a spiral corundum tube, and the spiral tube reactor is heated by a heating furnace with a length of 1.5-45 m and an inner cavity diameter of 0.5-10 m; preferably, the length of the spiral tube reactor tube is 15-30 m, the small diameter is 0.04-0.06 m, the large diameter is 0.5-1 m, the number of turns is 50-100, the length of the heating furnace is 14-29 m, and the inner cavity diameter is 0.6-1.2 m. The method is prepared by any one of claims 1-9.

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