Method and device for preparing single-walled carbon nanotubes through solid-liquid feeding

Abstract

The invention provides a method and a device for preparing a single-walled carbon nanotube through solid-liquid feeding. The method comprises the following steps: mixing and stirring an alcohol solvent, a metal compound catalyst, a cocatalyst and an etching agent in proportion to form a dispersion liquid; the reducing gas and the protective gas form mixed gas; respectively feeding the dispersion liquid, a solid catalyst and mixed gas into an evaporation chamber for dispersion, then feeding into a reaction furnace through a glass tube to generate a single-walled carbon nanotube, and collecting a crude product every 30min for purification treatment. According to the invention, a solid-liquid combined feeding mode is innovatively adopted, a feeding strategy of a catalyst and a carbon source is optimized, reaction parameters are adjusted, film formation of the single-walled carbon nanotubes is avoided, powder formation of the single-walled carbon nanotubes is more facilitated, and the composite material has high dispersibility and is easier to mix and disperse in materials such as rubber, plastic and a battery conductive agent; and moreover, the catalyst conversion rate and the production rate of the single-walled carbon nanotube are improved, so that a high-efficiency, low-cost and stable-quality product is obtained, and the method is suitable for large-scale production.

Description

Technical Field

[0001] The present application relates to the technical field of single-walled carbon nanotube preparation, and in particular to a method and a device for preparing single-walled carbon nanotubes using solid and liquid feeds. Background Art

[0002] Carbon nanotubes (CNTs) are nanoscale tubular structures made of rolled graphene sheets, with small diameter and large aspect ratio. They have excellent thermal conductivity, electrical conductivity, corrosion resistance, self-lubrication, biocompatibility and mechanical properties. CNTs show strong toughness, strength and elastic modulus, with a tensile strength of about 100 times that of steel, a density of less than 20% of steel, and an elastic modulus of up to TPa, which is comparable to diamond. From an electronics point of view, CNTs are formed by the curling of graphene sheets, with a spiral, tubular, seamless hollow structure, and the carbon atoms of graphite are connected by SP 2 Hybrid structure, each carbon atom has an unpaired electron located in the atomic P orbital, and CNTs are generated by graphite conversion, so there will be lone pairs of electrons freely swimming along the tube wall, so CNTs have excellent electrical conductivity. Due to its large aspect ratio, it has a strong ability to exchange heat along the length direction, and it has been found through research that the thermal conductivity of CNTs increases with the decrease of its tube diameter, and the fewer the number of tube layers, the stronger the thermal conductivity. In recent years, carbon nanotube materials have developed very rapidly, especially in many fields such as materials science, fault diagnosis, scientific electronics, radar absorbing stealth technology, etc., which has had a significant impact.

[0003] The preparation method of SWCNT mainly includes: laser ablation, arc discharge method, chemical vapor deposition (CVD), etc., wherein the chemical vapor deposition method is simple to operate and has good controllability, and is considered to be the most potential method for preparing SWCNT. The traditional solid feed method has the advantages of simplicity and high yield, but because the solid catalyst does not have a good dispersion effect in the liquid medium, it is impossible to achieve the best catalytic effect and catalytic activity, resulting in the poor quality of the obtained single-walled carbon nanotube. In addition, the liquid feed method can improve the dispersibility and reaction uniformity of the raw material, but will produce the risk of corrosion risk of the reaction equipment and increase the production cost of the gas, when controlling the low-speed feed, it will also cause the production efficiency to become low. The present application is intended to be able to organically combine solid feed and liquid feed by studying a method for simultaneously carrying out solid-liquid feeding, giving full play to the advantages of the two, and providing a new method for the efficient and high-quality preparation of single-walled carbon nanotubes. Summary of the invention

[0004] The present application is made in view of the above-mentioned problems, and its purpose is to significantly improve the utilization rate of the catalyst and enhance the decomposition efficiency of the carbon source, thereby improving the catalyst conversion rate and production rate of single-walled carbon nanotubes without sacrificing the Raman G / D ratio. The application is suitable for large-scale production and is widely used in the industrial field. A method and preliminary device for preparing single-walled carbon nanotubes by solid-liquid mixed feed are provided.

[0005] The first aspect of the present application provides a method for preparing single-walled carbon nanotubes by solid-liquid feeding, comprising the following steps:

[0006] (1) Preparation of single-walled carbon nanotubes: alcohol solvent, metal compound catalyst, co-catalyst and etchant are mixed and stirred in proportion to form a dispersion; reducing gas and protective gas form a mixed gas; the dispersion, solid catalyst and mixed gas are respectively fed into an evaporation chamber for dispersion, and then enter a reaction furnace through a glass tube to produce single-walled carbon nanotubes, and a crude product is collected every 30 minutes;

[0007] (2) Purification of crude product.

[0008] In any embodiment, the mixed gas acetylene and nitrogen are mixed and ventilated through a preheated gas mixing tank in a ratio of 1000-9000:500-4500 sccm, and the constant temperature when entering the furnace tube is maintained at 1150-1200°C; the feed rate of the dispersion is 500-700 μL / min, and the feed rate of the solid catalyst is 1-7 μg / min; the solid feeder and the liquid catalyst are fed at a fixed rate.

[0009] In any embodiment, the metal compound can be selected from one or more of ferric acetate, ferric chloride, ferrocene and iron sulfide; the co-catalyst can be selected from one or more of thiophene, ethanethiol, thiophenol and selenophene; the etchant can be selected from one or more of water, ethylene glycol and acetonitrile.

[0010] In any embodiment, the solid catalyst can be selected from one or more of ferric acetate, ferric chloride, ferrocene and ferric sulfide, and the mass ratio of the solid catalyst to the metal compound is 1:2-10.

[0011] In any embodiment, the metal compound, alcohol, co-catalyst and etchant are used in a ratio of 1-8 g: 50-150 mL: 1-4 mL: 20-500 μL.

[0012] In any embodiment, before liquid feeding, the continuous stirring temperature of the dispersion is 40-60°C; and the furnace tube temperature of the reaction furnace is 1200-1250°C.

[0013] In any embodiment, the crude product is purified by: first, continuously calcining the crude product at a high temperature under the condition of introducing oxygen; second, adding a certain concentration of carbon dioxide to the horizontal tube furnace to remove crude iron oxide impurities; finally, the crude powder subjected to the above treatment is placed in a certain concentration of concentrated sulfuric acid or concentrated hydrochloric acid at a specific temperature and stirred to remove residual metal impurities and obtain pure powder.

[0014] In any embodiment, the temperature for high-temperature calcination of the crude product is 1200-1600° C., and the heating rate is 5-10° C. / min.

[0015] In any embodiment, during the purification, the rate of oxygen introduction is 50-1000sccm for 1-3h; the rate of carbon dioxide introduction is 1000-2000sccm for 1-1.5h; the temperature of acid purification is 40-80°C, and the stirring time is 3-10h.

[0016] The second aspect of the present application also provides a method and device for preparing single-walled carbon nanotubes by solid-liquid feed, including a gas cylinder, a gas mixing tank, an evaporation chamber, a vertical tube furnace, a liquid sampler, a solid sampler and a collection box, wherein the gas cylinder, the gas mixing tank, the evaporation chamber vertical tube furnace and the collection box are connected in sequence, the liquid sampler and the solid sampler are connected to the evaporation chamber, an atomizer is provided on the top of the evaporation chamber and connected to the liquid sampler, the gas mixing tank is provided with a gas flowmeter, a quartz tube is provided in the vertical tube furnace, a bell mouth is provided on the top of the quartz tube, the bell mouth is connected to the evaporation chamber pipeline, and the collection box is provided with an exhaust pipe.

[0017] Beneficial effects of the present application: The invention innovatively adopts a solid-liquid combined feeding method to optimize the catalyst and carbon source delivery strategy, adjusts the reaction parameters, avoids the film formation of single-walled carbon nanotubes, and is more conducive to the powdering of single-walled carbon nanotubes. It has a high degree of dispersibility and is easier to mix and disperse in materials such as rubber, plastic and battery conductive agents. It has a smaller size and a larger specific surface area, which can provide more contact points to enhance the interaction force, which is conducive to uniform distribution in the base material. The powdered single-walled carbon nanotubes also have excellent conductivity and can significantly improve the conductive properties of the material. By finely controlling the ratio of solid and liquid raw materials and the timing of addition, the utilization rate of the catalyst can be significantly improved, and the decomposition efficiency of the carbon source can be enhanced, thereby improving the catalyst conversion rate and production rate of single-walled carbon nanotubes without sacrificing the Raman G / D ratio. The single-walled carbon nanotubes prepared by the solid-liquid combined feeding method have a 100% increase in yield compared to the simple liquid phase feeding method, and the Raman G / D ratio is increased by 156%, which is conducive to achieving high-efficiency, low-cost and stable quality products, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure of a device for preparing single-walled carbon nanotubes using solid-liquid feed in this application;

[0019] Figure 2 The scanning electron microscope (SEM) and Raman image (Raman) of the purified single-walled carbon nanotube (SWCNT) in Example 1 of the preparation method of this application;

[0020] Figure 3 The scanning electron microscope (SEM) and Raman image (Raman) of the purified single-walled carbon nanotube (SWCNT) in Example 2 of the preparation method of this application;

[0021] Figure 4 The scanning electron microscope (SEM) and Raman image (Raman) of the purified single-walled carbon nanotube (SWCNT) in Example 3 of the preparation method of this application;

[0022] Figure 5 The scanning electron microscope (SEM) and Raman image (Raman) of the purified single-walled carbon nanotube (SWCNT) in Example 4 of the preparation method of the present application;

[0023] Figure 6 The scanning electron microscope (SEM) and Raman images (Raman) of the purified single-walled carbon nanotubes (SWCNT) in Comparative Example 1;

[0024] Figure 7 The scanning electron microscope (SEM) and Raman images (Raman) of the purified single-walled carbon nanotubes (SWCNT) in Comparative Example 2 are shown.

[0025] Explanation of the reference numerals: gas cylinder 1; gas mixing tank 2; gas flow meter 21; evaporation chamber 3; atomizer 31; vertical tube furnace 4; quartz tube 41; bell mouth 42; liquid injector 5; syringe 51; automatic injection pump 52; solid injector 6; collection box 7; exhaust pipe 71. DETAILED DESCRIPTION

[0026] Hereinafter, a method for preparing single-walled carbon nanotubes from solid-liquid feed and an embodiment of the device thereof will be specifically disclosed with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of actually the same structures may be omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0027] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0028] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0029] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0030] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0031] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0032] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0033] The present invention aims to improve the utilization efficiency of catalysts and product quality while reducing production costs. Although the traditional solid feeding method is simple and has a high yield, the solid catalyst has insufficient dispersibility in the liquid medium, resulting in low catalytic activity, and it is impossible to effectively add a liquid promoter, resulting in a low G / D ratio of the obtained single-walled carbon nanotubes, showing poor quality. In addition, the liquid feeding method can improve the dispersibility and reaction uniformity of the raw materials, but it is easy to increase the corrosion risk of the reaction equipment and the production cost of the gas, especially when controlling the low-speed feeding, although high-quality products can be obtained, the production rate will be significantly slowed down. The method of simultaneously feeding solid and liquid can effectively avoid the film formation of single-walled carbon nanotubes, which is more conducive to the powdering of single-walled carbon nanotubes. Powdered single-walled carbon nanotubes are easier to mix and disperse in materials such as rubber, plastics and battery conductive agents due to their high dispersibility. This is because powdered single-walled carbon nanotubes have a smaller size and a larger specific surface area, which can provide more contact points to enhance the interaction force and help it to be evenly distributed in the base material. In addition, powdered single-walled carbon nanotubes also have excellent electrical conductivity, which can significantly improve the electrical conductivity of the material. The present invention innovatively combines two feeding methods, optimizes the delivery strategy of the catalyst and the carbon source, and adjusts the reaction parameters to achieve high efficiency, low cost and stable quality products. Specifically, by finely controlling the ratio and addition timing of solid and liquid raw materials, the utilization rate of the catalyst can be significantly improved, and the decomposition efficiency of the carbon source can be enhanced, thereby improving the catalyst conversion rate and production rate of single-walled carbon nanotubes without sacrificing the Raman G / D ratio. This technology is suitable for large-scale production and is expected to be widely used in the industrial field.

[0034] In one embodiment of the present application, the present application proposes a method for preparing single-walled carbon nanotubes by solid-liquid feeding, using alcohols as a carbon source, and mixing with a metal compound catalyst and a co-catalyst, and adding an etchant to reduce the amorphous carbon content to form a dispersion. In order to ensure uniform mixing, the liquid needs to be stirred continuously. After the reducing gas and the protective gas are mixed, the solid and liquid catalysts of the feed will be dispersed in the evaporation chamber, enter the reactor in the glass tube, and produce single-walled carbon nanotubes. The solid feeder and the liquid catalyst are fed at a fixed rate. The reducing gas and the protective gas in the mixing tank are preheated to ensure that a constant temperature is maintained when entering the furnace tube. The feed liquid enters the high-temperature furnace at a constant injection rate, and a sample is collected once within 30 minutes. Although high temperature is required to grow single-walled carbon nanotubes, the temperature required for the deposition process is relatively low to avoid long-term accumulation and carbonization of carbon nanotubes affecting the quality. Therefore, it is necessary to control the appropriate furnace tube temperature.

[0035] In the preparation, the solid feed has a large output. When the solid feed is used in large amounts, it is easy to produce impurities such as stone mills. If the amount is too little, it will affect the yield. The single-walled carbon nanotubes produced by liquid feed are of high quality. If too much liquid is added, it is easy to produce impurities such as multi-walled carbon nanotubes. If the amount is too little, it will affect the yield. The present application can prepare single-walled carbon nanotubes with high quality and high yield by combining solid and liquid feeds; and avoids the film formation of single-walled carbon nanotubes, which is conducive to the powdering of single-walled carbon nanotubes and has high dispersibility. The single-walled carbon nanotubes prepared by solid-liquid feeding are easier to mix and disperse in materials such as rubber, plastic and battery conductive agents, and improve the catalyst conversion rate and production rate of single-walled carbon nanotubes.

[0036] In one embodiment of the present application, the alcohol solvent is one or more of ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol; the metal compound can be one or more of ferric acetate, ferric chloride, ferrocene, and ferric sulfide.

[0037] An alcohol solvent, one of ethanol, n-propanol, n-butanol, n-pentanol and n-hexanol, with n-butanol being preferred as the solvent. Alcohol solvents not only help activate metal catalysts by generating -OH, but also provide suitable alkyl groups for the catalytic assembly of carbon nanotubes. Compared with short-chain alcohols, long-chain alcohols help provide more carbon sources to promote the growth of single-walled carbon nanotubes. However, long-chain alcohols have too high boiling points and are not easily volatile. During the chemical bond breaking process, they absorb heat, causing the local temperature to drop, which may cause the catalyst to generate other carbon impurities in the high temperature zone, especially when it is not fully dispersed and activated; therefore, n-butanol is more suitable as a solvent for providing a carbon source.

[0038] In one embodiment of the present application, the co-catalyst may be selected from one or more of thiophene, ethanethiol, thiophenol and selenophenephenol.

[0039] In one embodiment of the present application, the etchant may be selected from one or more of water, ethylene glycol and acetonitrile.

[0040] In one embodiment of the present application, the usage ratio of the metal compound, the liquid carbon source alcohol, the co-catalyst and the etchant is 1-8 g: 50-150 mL: 1-4 mL: 20-500 μL.

[0041] In one embodiment of the present application, the mixed dispersion should be continuously stirred before the liquid feed is performed.

[0042] In one embodiment of the present application, the protective gas is nitrogen, the reducing gas is acetylene, the ratio of reducing gas to protective gas is 1000-9000:500-4500sccm, and mixed ventilation is performed through a preheating mixing tank to maintain a constant temperature of 1150-1200°C when entering the furnace tube.

[0043] The mixed gas at 1150-1200° C. decomposes the carbon source to produce sufficient carbon atoms, and the catalyst can effectively catalyze the polymerization of carbon atoms to form a carbon nanotube structure.

[0044] In one embodiment of the present application, the speed of feeding the dispersion liquid is 500-700 μL / min.

[0045] In one embodiment of the present application, the solid catalyst can be selected from one or more of ferric acetate, ferric chloride, ferrocene and ferric sulfide, the feed rate is 1-7 μg / min, and the mass ratio of the solid catalyst to the metal compound is 1:2-10.

[0046] The solid catalyst and the metal compound are made of the same material to avoid introducing too many impurities; the mass ratio of the solid catalyst to the metal compound in the liquid is 1:2-10, with less solid catalyst, as too much solid catalyst will produce impurities such as graphite.

[0047] In one embodiment of the present application, the single-walled carbon nanotubes are prepared under the condition that the furnace tube temperature of the high-temperature furnace is 1150-1200°C.

[0048] In one embodiment of the present application, for the obtained sample crude product, first, in the method, the crude product is continuously calcined at high temperature to remove amorphous carbon attached to its surface. After this step, amorphous carbon reacts with oxygen to generate carbon dioxide and is discharged from the horizontal tube furnace. However, this step may cause the iron impurities in the crude product to be oxidized to iron oxide. Next, we perform secondary treatment in a horizontal tube furnace to supplement a certain concentration of carbon dioxide. Under high temperature conditions, carbon dioxide can decompose into carbon monoxide, thereby reducing the oxidized iron impurities to metallic iron. Thereafter, the present invention uses hydrochloric acid or sulfuric acid for subsequent treatment, taking advantage of the fact that the solubility of metallic iron is better than that of iron oxide, which is easier to remove. Finally, the present invention puts the crude powder treated as above into a certain concentration of concentrated sulfuric acid or concentrated hydrochloric acid at a specific temperature for stirring to remove residual metal impurities, thereby obtaining pure powder.

[0049] In one embodiment of the present application, the crude product is calcined in air at a high temperature of 1100-1600°C. In this process, oxygen reacts with amorphous carbon to generate carbon dioxide (CO2) or carbon monoxide (CO), which are discharged, thereby effectively removing the amorphous carbon. At the same time, calcination converts the amorphous carbon into a granular or flaky structure, increasing its contact area with oxygen, thereby improving the reaction efficiency and the graphitization level of the product.

[0050] In one embodiment of the present application, the crude product is calcined in air at a high temperature of 1100-1600°C. In this process, oxygen in the air reacts with amorphous carbon to generate carbon dioxide (CO2) or carbon monoxide (CO), and these gases are discharged to remove amorphous carbon. At the same time, calcination converts amorphous carbon into a granular or flaky structure, increasing its contact area with oxygen, thereby improving reaction efficiency and degree of graphitization. In order to remove the iron oxide impurities generated during calcination, 1000-2000sccm of carbon dioxide (CO2) can be introduced at 1100-1600°C for 1-1.5h. A small amount of carbon dioxide (CO2) will decompose into carbon monoxide (CO) at high temperature, which is more economical than directly introducing carbon monoxide. Iron oxide impurities react with carbon monoxide to generate metallic iron (Fe) and carbon dioxide (CO2), and carbon dioxide can be discharged through tail gas. This reaction realizes the collection and recycling of carbon dioxide. Metallic iron is easy to remove in hydrochloric acid (HCl) or sulfuric acid (H2SO4) solution, while the dissolution rate of iron oxide (Fe2O3) is slow, which affects the efficiency of removing metal impurities in single-walled carbon nanotubes. Therefore, the above method can effectively improve the purity and quality of single-walled carbon nanotubes.

[0051] In one embodiment of the present application, oxygen oxidation needs to complete the process of exposure to oxygen within 1-3 hours, while the heating rate is 5-10°C / min, and the gas flow rate is maintained between 50-1000sccm when oxygen is introduced.

[0052] In one embodiment of the present application, concentrated hydrochloric acid or other acid solutions can be selected to remove metal impurities. In addition, other acid solutions can also be considered to achieve the same purpose.

[0053] In one embodiment of the present application, in the process of purifying single-walled carbon nanotubes with an acidic solution, the temperature needs to be controlled at 40-80°C, and the stirring time is maintained for 3-10 hours. A method and device for preparing single-walled carbon nanotubes by solid-liquid feeding, comprising a gas cylinder 1, a gas mixing tank 2, an evaporation chamber 3, a vertical tube furnace 4, a liquid injector 5, a solid injector 6 and a collection box 7, wherein the gas cylinder 1, the gas mixing tank 2, the evaporation chamber 3, the vertical tube furnace 4 and the collection box 7 are connected in sequence, the liquid injector 5 and the solid injector 6 are connected to the evaporation chamber 3, the top of the evaporation chamber 3 is provided with an atomizer 31 connected to the liquid injector 5, the gas mixing tank 2 is provided with a gas flowmeter 21, the vertical tube furnace 4 is provided with a quartz tube 41, the top of the quartz tube 41 is provided with a bell mouth 42, the bell mouth 42 is connected to the evaporation chamber 3 pipeline, and the collection box 7 is provided with an exhaust pipe 71.

[0054] The solid sampler can be a powder particle solid feeder of the brand LAMBDA (product link:

[0055] https: / / www.chem17.com / st353974 / product_28385108.htm l).

[0056] Operation process:

[0057] 1. Turn on the power of the equipment, set the program, and heat up after the program is determined;

[0058] 2. Use the syringe 51 of the liquid sampler 5 to absorb an appropriate amount of raw material liquid, fix it on the automatic injection pump 52 of the liquid sampler 5, and at the same time add the solid raw material to the solid sampler 6, and set appropriate parameters;

[0059] 3. Set the appropriate flow rate and ratio, open the gas line and check for leaks. After confirming that there are no errors, introduce the mixed gas into the reaction tube;

[0060] 4. After the gas is stable and uniform, feed the solid and liquid and take samples every 30 minutes.

[0061] Example

[0062] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0063] Embodiment 1:

[0064] (1) Mix 2 g of ferrocene, 100 mL of n-butanol, 3 mL of thiophene, and 500 μL of ethylene glycol in the specified ratio and stir evenly. Raise the furnace temperature to 1200 °C, then mix 1000 sccm of reducing gas acetylene and 500 sccm of protective gas nitrogen and inject them into the mixing tank. The liquid feed rate is 600 μL / min, the solid catalyst feed rate is 1 μg / min, and samples are collected every 30 min.

[0065] (2) The tube furnace is heated to 1300°C at a heating rate of 10°C / min, and then oxygen is introduced at a rate of 1000sccm to continuously calcine the crude product at high temperature for 2 hours to remove amorphous carbon attached to its surface. After this step, the amorphous carbon reacts with oxygen to generate carbon dioxide, which is discharged from the horizontal tube furnace. Secondly, 1500sccm of carbon dioxide is introduced into the horizontal tube furnace and reacted for 1.5 hours to remove iron oxide impurities that may exist in the crude product. Under high temperature conditions, carbon dioxide can reduce iron oxide impurities to metallic iron that is easier to remove. Finally, the crude powder treated as above is put into a certain concentration of concentrated sulfuric acid or concentrated hydrochloric acid at a specific temperature at a temperature of 80°C and stirred for 10 hours to remove residual metal impurities, thereby obtaining pure powder.

[0066] After weighing and Raman testing, it was found that according to the embodiment 1, a machine with a tube length of 1m and a tube diameter of 60mm can produce 0.22g of crude single-walled carbon nanotubes in 8h, and the Raman G / D is 122.6.

[0067] Embodiment 2:

[0068] (1) Mix 2 g of ferrocene, 100 mL of n-butanol, 3 mL of thiophene, and 500 μL of ethylene glycol in the specified ratio and stir evenly. Raise the furnace temperature to 1200 °C, then mix 1000 sccm of reducing gas acetylene and 500 sccm of protective gas nitrogen and inject them into the mixing tank. The liquid feed rate is 600 μL / min, the solid catalyst feed rate is 3 μg / min, and samples are collected every 30 min.

[0069] (2) The tube furnace is heated to 1300°C at a heating rate of 10°C / min, and then oxygen is introduced at a rate of 1000sccm to continuously calcine the crude product at high temperature for 2 hours to remove amorphous carbon attached to its surface. After this step, the amorphous carbon reacts with oxygen to generate carbon dioxide, which is discharged from the horizontal tube furnace. Secondly, 1500sccm of carbon dioxide is introduced into the horizontal tube furnace and reacted for 1.5 hours to remove iron oxide impurities that may exist in the crude product. Under high temperature conditions, carbon dioxide can reduce iron oxide impurities to metallic iron that is easier to remove. Finally, the crude powder treated as above is put into a certain concentration of concentrated sulfuric acid or concentrated hydrochloric acid at a specific temperature at a temperature of 80°C and stirred for 10 hours to remove residual metal impurities, thereby obtaining pure powder.

[0070] After weighing and Raman testing, it was found that according to the embodiment 1, a machine with a tube length of 1m and a tube diameter of 60mm can produce 0.25g of crude single-walled carbon nanotubes in 8h, and the Raman G / D is 141.0.

[0071] Implementation Example 3:

[0072] (1) Mix 2 g of ferrocene, 100 mL of n-butanol, 3 mL of thiophene, and 500 μL of ethylene glycol in the specified ratio and stir evenly. Raise the furnace temperature to 1200 °C, then mix 1000 sccm of reducing gas acetylene and 500 sccm of protective gas nitrogen and inject them into the mixing tank. The liquid feed rate is 600 μL / min, the solid catalyst feed rate is 5 μg / min, and samples are collected every 30 min.

[0073] (2) The tube furnace is heated to 1300°C at a heating rate of 10°C / min, and then oxygen is introduced at a rate of 1000sccm to continuously calcine the crude product at high temperature for 2 hours to remove amorphous carbon attached to its surface. After this step, the amorphous carbon reacts with oxygen to generate carbon dioxide, which is discharged from the horizontal tube furnace. Secondly, 1500sccm of carbon dioxide is introduced into the horizontal tube furnace and reacted for 1.5 hours to remove iron oxide impurities that may exist in the crude product. Under high temperature conditions, carbon dioxide can reduce iron oxide impurities to metallic iron that is easier to remove. Finally, the crude powder treated as above is put into a certain concentration of concentrated sulfuric acid or concentrated hydrochloric acid at a specific temperature at a temperature of 80°C and stirred for 10 hours to remove residual metal impurities, thereby obtaining pure powder.

[0074] After weighing and Raman testing, it was found that according to the embodiment 1, a machine with a tube length of 1 m and a tube diameter of 60 mm can produce 0.38 g of crude single-walled carbon nanotubes in 8 hours, and the Raman G / D is 182.0.

[0075] Embodiment 4:

[0076] (1) Mix 2 g of ferrocene, 100 mL of n-butanol, 3 mL of thiophene, and 500 μL of ethylene glycol in the specified ratio and stir evenly. Raise the furnace temperature to 1200 °C, then mix 1000 sccm of reducing gas acetylene and 500 sccm of protective gas nitrogen and inject them into the mixing tank. The liquid feed rate is 600 μL / min, the solid catalyst feed rate is 7 μg / min, and samples are collected every 30 min.

[0077] (2) The tube furnace is heated to 1300°C at a heating rate of 10°C / min, and then oxygen is introduced at a rate of 1000sccm to continuously calcine the crude product at high temperature for 2 hours to remove amorphous carbon attached to its surface. After this step, the amorphous carbon reacts with oxygen to generate carbon dioxide, which is discharged from the horizontal tube furnace. Secondly, 1500sccm of carbon dioxide is introduced into the horizontal tube furnace and reacted for 1.5 hours to remove iron oxide impurities that may exist in the crude product. Under high temperature conditions, carbon dioxide can reduce iron oxide impurities to metallic iron that is easier to remove. Finally, the crude powder treated as above is put into a certain concentration of concentrated sulfuric acid or concentrated hydrochloric acid at a specific temperature at a temperature of 80°C and stirred for 10 hours to remove residual metal impurities, thereby obtaining pure powder.

[0078] After weighing and Raman testing, it was found that in Example 1, a machine with a tube length of 1m and a tube diameter of 60mm could produce 0.20g of crude single-walled carbon nanotubes in 8h, and the Raman G / D was 172.9.

[0079] Comparative Example 1:

[0080] The scheme of comparative example 1 is the same as the method of embodiment 1, except that the feed rate of the solid catalyst in the experimental scheme is 10 μg / min.

[0081] After weighing and Raman testing, it was found that according to the embodiment 1, a machine with a tube length of 1m and a tube diameter of 60mm can produce 0.14g of crude single-walled carbon nanotubes in 8h, and the Raman G / D is 71.2.

[0082] Comparative Example 2:

[0083] The scheme of comparative example 1 is the same as that of example 1, except that the feed rate of the solid catalyst in the experimental scheme is 0 μg / min.

[0084] After weighing and Raman testing, it was found that according to the embodiment 1, a machine with a tube length of 1m and a tube diameter of 60mm can produce 0.19g of crude single-walled carbon nanotubes in 8h, and the Raman G / D is 88.8.

[0085] Through Examples 1-4 and the corresponding Figure 2-5It can be concluded that as the feeding rate of the solid catalyst increases, the G / D ratio and output of the single-walled carbon nanotubes in the corresponding experimental scheme show a trend of first increasing and then decreasing, wherein the G / D ratio and output corresponding to the solid catalyst feeding rate of 7 μg / min are the largest. Therefore, the feeding rate of the solid catalyst needs to be maintained within an appropriate range and is not suitable to be too fast. For Comparative Example 1, the single-walled carbon nanotube product produced when the feeding rate of the solid catalyst is 10 μg / min has a relatively poor G / D ratio and output. This is because adding too much catalyst will lead to agglomeration effect, and the catalyst cannot give full play to its performance. For Comparative Example 2, since no solid catalyst was added, the catalytic effect was poor and the reaction failed to occur completely, resulting in a small G / D ratio and output. Therefore, the present invention embodies the necessity and selectivity of preparing single-walled carbon nanotubes by preparing solid-liquid mixed feed.

[0086] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing single-walled carbon nanotubes by solid-liquid feeding, characterized in that: The following steps are involved: (1) Preparation of single-walled carbon nanotubes: alcohol solvent, metal compound catalyst, co-catalyst and etchant are mixed and stirred in proportion to form a dispersion; reducing gas and protective gas form a mixed gas; the dispersion, solid catalyst and mixed gas are respectively fed into an evaporation chamber for dispersion, and then enter a reaction furnace through a glass tube to produce single-walled carbon nanotubes, and a crude product is collected every 30 minutes; (2) Purification of crude product.

2. The method for preparing single-walled carbon nanotubes by solid-liquid feeding according to claim 1, characterized in that: The mixed gas acetylene and nitrogen are mixed and ventilated in a ratio of 1000-9000:500-4500sccm through a preheating mixing tank, and the constant temperature when entering the furnace tube is maintained at 1150-1200°C; the feed rate of the dispersion is 500-700μL / min, and the feed rate of the solid catalyst is 1-7μg / min; the solid feeder and the liquid catalyst are fed at a fixed rate.

3. The method for preparing single-walled carbon nanotubes by solid-liquid feeding according to claim 1, characterized in that: The metal compound can be selected from one or more of ferric acetate, ferric chloride, ferrocene and ferric sulfide; the co-catalyst can be selected from one or more of thiophene, ethanethiol, thiophenol and selenophene; the etchant can be selected from one or more of water, ethylene glycol and acetonitrile.

4. The method for preparing single-walled carbon nanotubes by solid-liquid feeding according to claim 1, characterized in that: The usage ratio of the metal compound, alcohol, co-catalyst and etchant is 1-8g:50-150mL:1-4mL:20-500μL.

5. The method for preparing single-walled carbon nanotubes by solid-liquid feeding according to claim 1, characterized in that: The solid catalyst can be selected from one or more of ferric acetate, ferric chloride, ferrocene and ferric sulfide, and the mass ratio of the solid catalyst to the metal compound is 1:2-10.

6. The method for preparing single-walled carbon nanotubes by solid-liquid feeding according to claim 1, characterized in that: Before liquid feeding, the continuous stirring temperature of the dispersion is 40-60°C; the furnace tube temperature of the reaction furnace is 1150-1200°C.

7. The method for preparing single-walled carbon nanotubes by solid-liquid feeding according to claim 1, characterized in that: The purification treatment of the crude product is as follows: first, the crude product is continuously calcined at a high temperature under the condition of oxygen; second, a certain concentration of carbon dioxide is added to the horizontal tube furnace to remove crude iron oxide impurities; finally, the crude powder subjected to the above treatment is put into a certain concentration of concentrated sulfuric acid or concentrated hydrochloric acid at a specific temperature and stirred to remove residual metal impurities and obtain pure powder.

8. The method for preparing single-walled carbon nanotubes by solid-liquid feeding according to claim 7, characterized in that: The temperature for high-temperature calcination of the crude product is 1200-1600°C, and the heating rate is 5-10°C / min.

9. The method for preparing single-walled carbon nanotubes by solid-liquid feeding according to claim 7, characterized in that: During the purification, the rate of oxygen introduction is 50-1000sccm, and the time is 1-3h; the rate of carbon dioxide introduction is 1000-2000sccm, and the time is 1-1.5h; the temperature of acid purification is 40-80°C, and the stirring time is 3-10h.

10. A device for preparing single-walled carbon nanotubes by solid-liquid feeding, comprising a gas cylinder, a gas mixing tank, an evaporation chamber, a vertical tube furnace, a liquid sampler, a solid sampler and a collection box, wherein the gas cylinder, the gas mixing tank, the evaporation chamber vertical tube furnace and the collection box are connected in sequence, the liquid sampler and the solid sampler are connected to the evaporation chamber, an atomizer is provided on the top of the evaporation chamber and connected to the liquid sampler, the gas mixing tank is provided with a gas flowmeter, a quartz tube is provided in the vertical tube furnace, a bell mouth is provided on the top of the quartz tube, the bell mouth is connected to the evaporation chamber pipeline, and the collection box is provided with an exhaust pipe.

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