Preparation process of high-purity single-walled carbon nanotube

Abstract

The invention discloses a preparation process of a high-purity single-walled carbon nanotube, and relates to the technical field of carbon nanomaterials. According to the method, the mixed gas carbon source and the liquid carbon source are used for preparing the single-walled carbon nanotube protomer, meanwhile, the gas carbon source can serve as carrier gas to input liquid carbon source steam into the reaction area, so that the integrity of the single-walled carbon nanotube is guaranteed, and then the low-boiling-point solvent is selected to be combined with water to purify the single-walled carbon nanotube protomer. Then, current injection is utilized to enable the low-boiling-point solvent to form a steam layer, the steam layer covers the surface of the single-walled carbon nanotube, the single-walled carbon nanotube is prevented from being excessively damaged, meanwhile, the exposed metal impurities are easier to oxidize in oxidizing gas, and then the pickling efficiency is improved; and the low-temperature buffer effect of the mixed liquid of the low-boiling-point solvent and the water is utilized to delay the oxidation rate, so that impurity carbon is preferentially oxidized, and efficient purification is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon nanomaterials, and particularly to a preparation process of high-purity single-walled carbon nanotubes. BACKGROUND

[0002] Carbon nanotubes are one-dimensional nanocarbon materials discovered in the early 1990s. Due to their excellent mechanical properties, electrical conductivity, thermal conductivity and chemical stability, they have shown broad application prospects in composite materials, electronic devices, energy storage and catalysis. Among them, single-walled carbon nanotubes have become a research hotspot in the field of nanomaterials due to their more regular tube wall structure, higher aspect ratio and more unique electrical and optical properties, and have shown irreplaceable role in high-performance conductive films, sensors, transistors and functional composites.

[0003] However, the large-scale preparation and high-purity acquisition of single-walled carbon nanotubes still face significant challenges. The common preparation methods at present mainly include arc discharge method, laser ablation method and chemical vapor deposition method. Among them, the chemical vapor deposition method has become the mainstream technology due to its relatively simple equipment, strong controllability and suitability for continuous production, but it usually needs to use metal catalysts in the preparation process, and the residual metal particles and amorphous carbon impurities after the reaction are difficult to completely remove. In addition, the choice and supply mode of carbon source directly affect the growth efficiency, tube diameter distribution and structural integrity of carbon nanotubes. Although the traditional gas-phase carbon source is easy to control, the carbon supply is not uniform; although the liquid-phase carbon source can provide abundant carbon atoms, its vaporization and transportation process is not easy to control, which easily leads to catalyst deactivation or carbon tube structure defects.

[0004] In terms of purification, the existing technology mostly adopts high-temperature oxidation, strong acid treatment or combined purification process, aiming to remove metal catalysts and amorphous carbon. However, these methods often cause damage to the carbon nanotubes themselves, such as tube wall oxidation, structure fracture or functionalization inactivation, thereby affecting their intrinsic properties. In addition, the removal efficiency of impurities in the conventional purification process is limited, especially the metal particles embedded inside the carbon tube bundle or closely combined with the carbon tube, which are difficult to completely remove through simple acid washing or oxidation.

[0005] Therefore, developing a preparation process that can realize structural integrity, low impurity content at the growth stage, and efficient removal of residual metal and amorphous carbon in subsequent purification while maximizing the protection of carbon tube structure, becomes the key to promoting the practical application of single-walled carbon nanotubes. The present application aims to solve the above problems by providing a high-purity single-walled carbon nanotube preparation method combining mixed carbon source supply and low-temperature buffer purification to improve the purity, structural integrity and process controllability of the product. SUMMARY

[0006] The present application aims to provide a preparation process of high-purity single-walled carbon nanotubes to solve the problems in the prior art.

[0007] To solve the above technical problems, the present application provides the following technical solutions: a preparation method of high-purity single-walled carbon nanotubes, comprising the following steps: (1) under the condition of 1000-1200 ℃, the catalyst is atomized by nitrogen gas with a flow rate of 150 sccm and injected into the reaction chamber, then liquid carbon source and mixed gas are simultaneously introduced for reaction for 60 min, and then the single-walled carbon nanotube raw material is collected by a filter membrane with a pore size of 0.22 μm; (2) the single-walled carbon nanotube raw material is dispersed in a mixed solvent, after 40 kHz ultrasonic treatment for 30 min, a complexing agent is added, and stirred at 300 rpm for 1 h, then the complex is separated by filtration, washed with the mixed solvent for 3 times, then a pulse voltage is applied under the protection of nitrogen gas with a flow rate of 150 sccm, after treatment, placed in an acid solution, stirred at 500 rpm under ice bath condition for 2 h, then heated to 80-100 ℃, reacted for 1 h to dissolve the residual metal oxide, filtered to obtain the solid, washed with deionized water until the washing liquid has a pH of 7, and finally dried at 70 ℃ under a vacuum degree of 100 Pa for 10 h to obtain high-purity single-walled carbon nanotubes.

[0008] Further, the catalyst in step (1) is composed of iron, cobalt and molybdenum, and the mass ratio of the three is 3:1:1, and the particle size of the three is 30 nm; the amount of the catalyst is 0.1-0.5 g / h.

[0009] Further, the flow rate of the liquid carbon source in step (1) is 10-20 mL / h.

[0010] Further, the liquid carbon source in step (1) is at least one of ethanol, acetone, n-butanol, methanol and benzyl alcohol.

[0011] Further, the flow rate of the mixed gas in step (1) is 500 sccm.

[0012] Further, the mixed gas in step (1) is composed of a gaseous carbon source and hydrogen, and the volume ratio of the two is 3-5:5-8.

[0013] Further, the gaseous carbon source is at least one of methane, ethylene and carbon monoxide.

[0014] Further, the mixed solvent in step (2) is composed of a low-boiling-point solvent and deionized water, and the mass ratio of the two is 12:8; the low-boiling-point solvent is at least one of ethanol and isopropyl alcohol.

[0015] Further, the mass ratio of the single-walled carbon nanotube raw material, the mixed solvent and the complexing agent in step (2) is 1:150:0.1.

[0016] Further, the process parameters of the pulse voltage in step (2) are: voltage 4-10V, 10-20mA / cm 2 , temperature 500-600℃, and time 10min.

[0017] Compared with the prior art, the present application has the following beneficial effects: The present application uses mixed gas carbon source and liquid carbon source to prepare single-walled carbon nanotube raw material, and the gas carbon source can be used as a carrier gas to input the liquid carbon source vapor into the reaction zone, promote the atomization and diffusion of the liquid, and then make the carbon source uniformly cover the surface of the catalyst, provide continuous and stable carbon source supply, and avoid catalyst deactivation due to carbon source interruption, wherein the surface impurity carbon is removed by reacting with hydrogen, thereby ensuring the integrity of the single-walled carbon nanotube and achieving preliminary purity guarantee, and then a low-boiling-point solvent is selected to combine with water to purify the single-walled carbon nanotube raw material, a coordination bond is formed between the hydroxyl group and the metal impurities, the bonding force between the metal and the carbon tube is weakened, the metal impurities fall off from the surface of the carbon tube, and are exposed to the solvent, then the low-boiling-point solvent forms a vapor layer on the surface of the single-walled carbon nanotube by using the Joule heat generated by the instantaneous high current, the oxidation rate is slowed down, the lattice structure of the single-walled carbon nanotube is prevented from being excessively damaged, the exposed metal impurities are more easily oxidized to metal oxides in the oxidation gas, the pickling efficiency is improved, and the low-temperature buffering effect of the mixed liquid of the low-boiling-point solvent and water can slow down the oxidation rate, part of the heat is taken away by volatilization, the impurity carbon is preferentially oxidized to carbon dioxide or carbon monoxide, thereby retaining the single-walled carbon nanotube, and realizing efficient purification. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0019] In order to more clearly illustrate the method provided by the present application, the following embodiments are described in detail. In the following embodiments, the test methods of various indexes of high-purity single-walled carbon nanotubes produced are as follows: The same size of the examples and the comparative examples is taken according to GB / T32868, and the purity is detected by TG analysis. The temperature is increased from room temperature to 800℃ at a rate of 10℃ / min. The purity calculation formula is: single-walled carbon nanotube purity (%) = [1-(amorphous carbon mass loss%+metal impurity mass loss%)]x100, and the purity of the single-walled carbon nanotube is obtained.

[0020] Example 1 (1) under the condition of 1000℃, the catalyst is atomized by nitrogen gas with a flow rate of 150 sccm, and then injected into the reaction chamber, followed by simultaneously introducing ethanol with a flow rate of 10 mL / h and mixed gas with a flow rate of 500 sccm, and then the reaction is carried out for 60 min, and then the single-walled carbon nanotube precursor is collected by using a filter membrane with a pore size of 0.22 μm; the catalyst is composed of iron, cobalt and molybdenum, and the mass ratio of the three is 3:1:1, and the particle size of the three is 30 nm; the amount of the catalyst is 0.1 g / h; the mixed gas is composed of methane and hydrogen, and the volume ratio of the two is 3:5; (2) the single-walled carbon nanotube precursor is dispersed in a mixed solvent, and after 40 kHz ultrasonic treatment for 30 min, a complexing agent is added, and then stirred at 300 rpm for 1 h, and then the complex is separated by filtration, and then washed with the mixed solvent for 3 times, and then a pulse voltage is applied under the protection of nitrogen gas with a flow rate of 150 sccm, and the process parameters are as follows: voltage is 4 V, 10 mA / cm 2 , temperature is 500℃, and time is 10 min, after treatment, placed in an acid solution, stirred at 500 rpm under ice bath condition for 2 h, and then heated to 80℃, reacted for 1 h, dissolved the residual metal oxide, filtered to obtain the solid, washed with deionized water until the washing liquid is pH 7, and finally dried at 70℃ under vacuum degree of 100 Pa for 10 h, to obtain high-purity single-walled carbon nanotubes; the mass ratio of the single-walled carbon nanotube precursor, the mixed solvent and the complexing agent is 1:150:0.1; the mixed solvent is composed of ethanol and deionized water, and the mass ratio of the two is 12:8; the complexing agent is ethylenediaminetetraacetic acid; the acid solution is composed of 50wt% sulfuric acid solution, 30wt% nitric acid solution and 20wt% hydrogen peroxide solution, and the mass ratio of the three is 5:2:1.

[0021] Example 2 (1) under the condition of 1100℃, the catalyst is atomized by nitrogen gas with a flow rate of 150 sccm, and then injected into the reaction chamber, followed by simultaneously introducing ethanol with a flow rate of 15 mL / h and mixed gas with a flow rate of 500 sccm, and then the reaction is carried out for 60 min, and then the single-walled carbon nanotube precursor is collected by using a filter membrane with a pore size of 0.22 μm; the catalyst is composed of iron, cobalt and molybdenum, and the mass ratio of the three is 3:1:1, and the particle size of the three is 30 nm; the amount of the catalyst is 0.3 g / h; the mixed gas is composed of methane and hydrogen, and the volume ratio of the two is 4:6; (2) the single-walled carbon nanotube precursor is dispersed in a mixed solvent, and after 40 kHz ultrasonic treatment for 30 min, a complexing agent is added, and then stirred at 300 rpm for 1 h, and then the complex is separated by filtration, and then washed with the mixed solvent for 3 times, and then a pulse voltage is applied under the protection of nitrogen gas with a flow rate of 150 sccm, and the process parameters are as follows: voltage is 6 V, 15 mA / cm 2, temperature is 550℃, time is 10 min, after treatment, in acid solution, under ice bath condition, 500 rpm stirring 2 h, then warm up to 90℃, reaction 1 h, dissolve residual metal oxide, filter to take solid, wash with deionized water until the washing liquid is pH 7, finally at 70℃, vacuum degree is 100 Pa, dry 10 h, get high purity single-walled carbon nanotube; The mass ratio of the single-walled carbon nanotube raw body, mixed solvent, complexing agent is 1:150:0.1; The mixed solvent is composed of ethanol, deionized water, and the mass ratio is 12:8; The complexing agent is ethylenediaminetetraacetic acid; The acid solution is composed of 50wt% sulfuric acid solution, 30wt% nitric acid solution, 20wt% hydrogen peroxide solution, and the mass ratio is 5:2:1.

[0022] Example 3 (1) Under the condition of 1200℃, the catalyst is atomized by nitrogen gas with a flow rate of 150sccm, injected into the reaction chamber, then, ethanol with a flow rate of 20mL / h and mixed gas with a flow rate of 500sccm are simultaneously introduced, reaction is carried out for 60min, then collected by filter membrane with a pore size of 0.22μm, get single-walled carbon nanotube raw body; The catalyst is composed of iron, cobalt, molybdenum, and the mass ratio is 3:1:1, the particle size of the three is 30nm; The amount of catalyst used is 0.5g / h; The mixed gas is composed of methane, hydrogen, and the volume ratio is 5:8; (2) Disperse the single-walled carbon nanotube raw body in the mixed solvent, after 40kHz ultrasonic treatment for 30min, add the complexing agent, stir at 300rpm for 1h, then separate the complex by filtration, then wash with mixed solvent for 3 times, then apply pulse voltage under the protection of nitrogen gas with a flow rate of 150sccm, the process parameters: voltage is 10V, 20mA / cm 2 , temperature is 550℃, time is 10 min, after treatment, in acid solution, under ice bath condition, 500 rpm stirring 2 h, then warm up to 90℃, reaction 1 h, dissolve residual metal oxide, filter to take solid, wash with deionized water until the washing liquid is pH 7, finally at 70℃, vacuum degree is 100 Pa, dry 10 h, get high purity single-walled carbon nanotube; The mass ratio of the single-walled carbon nanotube raw body, mixed solvent, complexing agent is 1:150:0.1; The mixed solvent is composed of ethanol, deionized water, and the mass ratio is 12:8; The complexing agent is ethylenediaminetetraacetic acid; The acid solution is composed of 50wt% sulfuric acid solution, 30wt% nitric acid solution, 20wt% hydrogen peroxide solution, and the mass ratio is 5:2:1.

[0023] Example 4 (1) under the condition of 1100℃, the catalyst is atomized by nitrogen gas with a flow rate of 150sccm, and then injected into the reaction chamber, followed by simultaneously introducing ethanol with a flow rate of 15mL / h and mixed gas with a flow rate of 200sccm, and then the reaction is carried out for 60min, and then the single-walled carbon nanotube precursor is collected by using a filter membrane with a pore size of 0.22μm; the catalyst is composed of iron, cobalt and molybdenum, and the mass ratio of the three is 3:1:1, and the particle size of the three is 30nm; the amount of the catalyst is 0.3g / h; the mixed gas is composed of methane and hydrogen, and the volume ratio of the two is 4:6; (2) the single-walled carbon nanotube precursor is dispersed in a mixed solvent, and then treated by ultrasonic wave with a frequency of 40kHz for 30min, and then a complexing agent is added, and then stirred at 300rpm for 1h, and then the complex is separated by filtration, and then washed with the mixed solvent for 3 times, and then a pulse voltage is applied under the protection of nitrogen gas with a flow rate of 150sccm, and the process parameters of the pulse voltage are as follows: voltage is 6V, current is 15mA / cm 2 , temperature is 550℃, and time is 10min, and then the treated single-walled carbon nanotube precursor is placed in an acid solution, and then stirred at 500rpm for 2h under the condition of ice bath, and then the temperature is increased to 90℃, and then reacted for 1h, and then the residual metal oxide is dissolved, and then the solid is obtained by filtration, and then washed with deionized water until the pH of the washing liquid is 7, and finally dried at 70℃ under the condition of vacuum degree of 100Pa for 10h, and then the high-purity single-walled carbon nanotube is obtained; the mass ratio of the single-walled carbon nanotube precursor, the mixed solvent and the complexing agent is 1:150:0.1; the mixed solvent is composed of ethanol and deionized water, and the mass ratio of the two is 12:8; the complexing agent is ethylenediaminetetraacetic acid; the acid solution is composed of 50wt% sulfuric acid solution, 30wt% nitric acid solution and 20wt% hydrogen peroxide solution, and the mass ratio of the three is 5:2:1.

[0024] Example 5 (1) under the condition of 1100℃, the catalyst is atomized by nitrogen gas with a flow rate of 150sccm, and then injected into the reaction chamber, followed by simultaneously introducing ethanol with a flow rate of 15mL / h and mixed gas with a flow rate of 200sccm, and then the reaction is carried out for 60min, and then the single-walled carbon nanotube precursor is collected by using a filter membrane with a pore size of 0.22μm; the catalyst is composed of iron, cobalt and molybdenum, and the mass ratio of the three is 3:1:1, and the particle size of the three is 30nm; the amount of the catalyst is 0.3g / h; the mixed gas is composed of methane and hydrogen, and the volume ratio of the two is 4:6; (2) the single-walled carbon nanotube precursor is dispersed in a mixed solvent, and then treated by ultrasonic wave with a frequency of 40kHz for 30min, and then a complexing agent is added, and then stirred at 300rpm for 1h, and then the complex is separated by filtration, and then washed with the mixed solvent for 3 times, and then a pulse voltage is applied under the protection of nitrogen gas with a flow rate of 150sccm, and the process parameters of the pulse voltage are as follows: voltage is 6V, current is 15mA / cm 2, temperature is 550 ℃, time is 3 min, after treatment, placed in the acid solution, under ice bath conditions, 500 rpm stirring 2 h, and then warmed to 90 ℃, reaction 1 h, dissolve the residual metal oxide, filter to take the solid, washed with deionized water until the washing liquid is pH 7, finally at 70 ℃, vacuum degree is 100 Pa, drying 10 h, get high purity single-walled carbon nanotubes; The mass ratio of single-walled carbon nanotube raw body, mixed solvent, complexing agent is 1:150:0.1; The mixed solvent consists of ethanol, deionized water, and the mass ratio is 12:8; The complexing agent is ethylenediaminetetraacetic acid; The acid solution is composed of 50wt% sulfuric acid solution, 30wt% nitric acid solution, 20wt% hydrogen peroxide solution, and the mass ratio is 5:2:1.

[0025] Comparative Example 1 (1) under the condition of 1100 ℃, the catalyst is atomized by nitrogen gas with a flow rate of 150 sccm, injected into the reaction chamber, then, at the same time, ethanol with a flow rate of 15 mL / h is introduced, reaction is carried out for 60 min, and then collected by filter membrane with a pore size of 0.22 μm to obtain single-walled carbon nanotube raw body; The catalyst is composed of iron, cobalt and molybdenum, and the mass ratio is 3:1:1, and the particle size of the three is 30 nm; The amount of catalyst used is 0.3 g / h; The mixed gas is composed of methane and hydrogen, and the volume ratio is 4:6; (2) the single-walled carbon nanotube raw body is dispersed in the mixed solvent, after 40 kHz ultrasonic treatment for 30 min, the complexing agent is added, 300 rpm stirring 1 h, then the complex is separated by filtration, and then washed with mixed solvent for 3 times, then pulse voltage is applied under the protection of nitrogen gas with a flow rate of 150 sccm, and the process parameters are: voltage is 6V, 15 mA / cm 2 , temperature is 550 ℃, time is 3 min, after treatment, placed in the acid solution, under ice bath conditions, 500 rpm stirring 2 h, and then warmed to 90 ℃, reaction 1 h, dissolve the residual metal oxide, filter to take the solid, washed with deionized water until the washing liquid is pH 7, finally at 70 ℃, vacuum degree is 100 Pa, drying 10 h, get high purity single-walled carbon nanotubes; The mass ratio of single-walled carbon nanotube raw body, mixed solvent, complexing agent is 1:150:0.1; The mixed solvent consists of ethanol, deionized water, and the mass ratio is 12:8; The complexing agent is ethylenediaminetetraacetic acid; The acid solution is composed of 50wt% sulfuric acid solution, 30wt% nitric acid solution, 20wt% hydrogen peroxide solution, and the mass ratio is 5:2:1.

[0026] Comparative Example 2 (1) under the condition of 1100℃, the catalyst is atomized by nitrogen gas with a flow rate of 150sccm, and then injected into the reaction chamber, followed by simultaneously inputting ethanol with a flow rate of 15mL / h and mixed gas with a flow rate of 500sccm, and then the reaction is carried out for 60min, and then the single-walled carbon nanotube precursor is collected by using a filter membrane with a pore size of 0.22μm; the catalyst is composed of iron, cobalt and molybdenum, and the mass ratio of the three is 3:1:1, and the particle size of the three is 30nm; the amount of the catalyst used is 0.3g / h; the mixed gas is composed of methane and hydrogen, and the volume ratio of the two is 4:6; (2) the single-walled carbon nanotube precursor is dispersed in a mixed solvent, and after 40kHz ultrasonic treatment for 30min, a complexing agent is added, and then stirred at 300rpm for 1h, and then the complex is separated by filtration, and then washed with the mixed solvent for 3 times, and then placed in an acid solution, and then stirred at 500rpm under the condition of ice bath for 2h, and then heated to 90℃, and then reacted for 1h to dissolve the residual metal oxide, and then filtered to obtain the solid, and then washed with deionized water until the washing liquid is pH 7, and then dried at 70℃ under the condition of vacuum degree of 100Pa for 10h to obtain high-purity single-walled carbon nanotubes; the mass ratio of the single-walled carbon nanotube precursor, the mixed solvent and the complexing agent is 1:150:0.1; the mixed solvent is composed of ethanol and deionized water, and the mass ratio of the two is 12:8; the complexing agent is ethylenediaminetetraacetic acid; the acid solution is composed of 50wt% sulfuric acid solution, 30wt% nitric acid solution and 20wt% hydrogen peroxide solution, and the mass ratio of the three is 5:2:1.

[0027] Effect example The performance analysis results of the high-purity single-walled carbon nanotubes obtained by using the examples 1 to 5 and the comparative examples 1 to 2 of the present application are shown in the following table 1.

[0028] Table 1 Purity (%) Example 1 98.6 Example 2 99.4 Example 3 98.9 Example 4 97.5 Example 5 96.1 Comparative Example 1 95.2 Comparative Example 2 93.8 From the comparison of the experimental data of the examples and the comparative examples in Table 1, it can be found that the present application uses mixed gas carbon source and liquid carbon source to prepare single-walled carbon nanotube raw material, and the gas carbon source can be used as carrier gas to input the liquid carbon source vapor into the reaction zone, promote the atomization and diffusion of the liquid, and then make the carbon source uniformly cover the surface of the catalyst, provide continuous and stable carbon source supply, avoid the deactivation of the catalyst due to the interruption of the carbon source, wherein the impurity carbon on the surface is removed by reacting with hydrogen, thereby ensuring the integrity of the single-walled carbon nanotube, and then a low-boiling-point solvent is selected to combine with water to purify the single-walled carbon nanotube raw material, the hydroxyl group in the low-boiling-point solvent forms a coordination bond with the metal impurities, which promotes the metal impurities to fall off from the surface of the carbon nanotube, then the low-boiling-point solvent forms a vapor layer on the surface of the single-walled carbon nanotube by the Joule heat generated by the instantaneous high current through the current injection, which delays the oxidation rate and avoids the single-walled carbon nanotube from being damaged excessively, and the exposed metal impurities are more easily oxidized in the oxidation gas, which improves the efficiency of pickling, and the low-temperature buffering effect of the mixed liquid of the low-boiling-point solvent and water can delay the oxidation rate, and part of the heat carried away by the volatilization of the low-boiling-point solvent, which preferentially makes the impurity carbon be oxidized, realizes efficient purification.

[0029] It will be apparent to those skilled in the art that the application is not limited to the details of the above-exemplified embodiments and that the application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the application being defined by the appended claims rather than the above description, and it is intended that all changes that come within the meaning and range of equivalency of the claims are embraced therein. Any reference signs in the claims should not be construed as limiting the claims to the figures in which the reference signs are used.

Claims

1. A method for preparing high-purity single-walled carbon nanotubes, characterized in that, Includes the following steps: (1) Under high temperature conditions, the catalyst is atomized by nitrogen and injected into the reaction chamber. Then, liquid carbon source and mixed gas are introduced simultaneously to carry out the reaction. The mixture is then collected by a filter membrane to obtain the original single-walled carbon nanotube. (2) The original single-walled carbon nanotubes were dispersed in a mixed solvent, ultrasonically treated, a complexing agent was added, and the mixture was stirred. Then the complex was separated by filtration and washed with a mixed solvent. Then, under nitrogen protection, a pulse voltage was applied. After treatment, the mixture was washed with acid and deionized water in sequence and dried to obtain high-purity single-walled carbon nanotubes.

2. The method for preparing high-purity single-walled carbon nanotubes according to claim 1, characterized in that, The catalyst in step (1) is composed of iron, cobalt and molybdenum in a mass ratio of 3:1:1, and the particle size of all three is 30 nm; the amount of the catalyst used is 0.1~0.5 g / h.

3. The method for preparing high-purity single-walled carbon nanotubes according to claim 1, characterized in that, The flow rate of the liquid carbon source in step (1) is 10~20 mL / h.

4. The method for preparing high-purity single-walled carbon nanotubes according to claim 1, characterized in that, The liquid carbon source in step (1) is at least one of ethanol, acetone, n-butanol, methanol, and benzyl alcohol.

5. The method for preparing high-purity single-walled carbon nanotubes according to claim 1, characterized in that, The flow rate of the mixed gas in step (1) is 500 sccm.

6. The method for preparing high-purity single-walled carbon nanotubes according to claim 1, characterized in that, The mixed gas in step (1) consists of a gaseous carbon source and hydrogen, with a volume ratio of 3~5:5~8.

7. The method for preparing high-purity single-walled carbon nanotubes according to claim 4, characterized in that, The gaseous carbon source is at least one of methane, ethylene, and carbon monoxide.

8. The method for preparing high-purity single-walled carbon nanotubes according to claim 1, characterized in that, The mixed solvent in step (2) consists of a low-boiling-point solvent and deionized water in a mass ratio of 12:8; the low-boiling-point solvent is at least one of ethanol and isopropanol.

9. The method for preparing high-purity single-walled carbon nanotubes according to claim 1, characterized in that, The mass ratio of the single-walled carbon nanotube precursor, mixed solvent, and complexing agent in step (2) is 1:150:0.

1.

10. The method for preparing high-purity single-walled carbon nanotubes according to claim 1, characterized in that, The process parameters for the pulse voltage in step (2) are: voltage 4~10V, 10~20mA / cm. 2 The temperature is 500~600℃ and the time is 10min.