Purification method of single-walled carbon nanotube
By subjecting crude single-walled carbon nanotubes to specific temperature calcination and high-speed shear dispersion, combined with organic acid reflux reaction, the problem of incomplete removal of metal impurities in existing technologies has been solved, achieving high-purity, high-yield purification and large-scale production of single-walled carbon nanotubes.
Patent Information
- Application Number
- CN202511541783.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-27
- Publication Date
- 2026-01-23
AI Technical Summary
Existing technologies struggle to efficiently remove metallic impurities from single-walled carbon nanotubes without damaging their structure, leading to performance degradation and hindering large-scale production.
By calcining crude single-walled carbon nanotubes at a specific temperature, combined with high-speed shear dispersion and organic acid reflux reaction, metallic impurities are removed, and the structural integrity of the carbon nanotubes is protected.
High-purity, high-yield purification of single-walled carbon nanotubes was achieved, making it suitable for large-scale production while maintaining the structure and properties of the carbon nanotubes.
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Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of carbon nanotube separation and purification, in particular to a single-wall carbon nanotube purification method. BACKGROUND
[0002] Single-wall carbon nanotubes (SWCNT) are composed of carbon atoms, and the geometric structure can be regarded as a single layer of graphene rolled up. The structure determines the properties, so single-wall carbon nanotubes have excellent electronic, mechanical, mechanical and other properties. The mainstream preparation technologies of arc discharge and chemical vapor deposition are to generate single-wall carbon nanotubes by using carbon source under the action of catalyst. After the preparation is completed, there are metal catalyst residues in the obtained product. These metal impurities seriously hinder the application of single-wall carbon nanotubes in the downstream industry.
[0003] The mainstream methods for removing metal impurities include strong acid oxidation method, density gradient method and liquid phase separation method. However, there are the following shortcomings, for example, the crude product is treated by high-temperature refluxing with concentrated nitric acid to selectively oxidize amorphous carbon and metal impurities. This method is widely used, but the strong acid environment can easily damage the structure of carbon nanotubes, resulting in shortening of tube length, increase of defects, significant decrease of intrinsic properties and decrease of electrical conductivity. Iodixanol and other media are used to form a density gradient, and single-wall carbon nanotubes and metal impurities are separated by high-speed centrifugation. However, this technology has high cost, low single processing capacity and low recovery rate, and is difficult to realize industrial application. Surfactants are used to disperse carbon nanotubes, and impurities are separated by centrifugation / chromatography. The selectivity is good, but the process is complex, depends on precise equipment, has low yield and is difficult to scale up.
[0004] Therefore, it is necessary to develop a new single-wall carbon nanotube purification method. SUMMARY
[0005] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the first aspect of the present application provides a single-wall carbon nanotube purification method, which can efficiently remove metal impurities without damaging the structure of single-wall carbon nanotubes, and realize large-scale production with high purity and high yield.
[0006] According to the first aspect of the present application, a single-wall carbon nanotube purification method is provided, which comprises the following steps: S1, the single-wall carbon nanotube crude product is first calcined I at 320-450℃, and then calcined II at 280-310℃ to obtain an intermediate I; S2, the intermediate I, a surfactant and water are mixed for shearing dispersion, and an intermediate II is obtained after solid-liquid separation; S3, the intermediate II and an organic acid are mixed for reflux reaction; and the single-wall carbon nanotube after purification is obtained after post-treatment.
[0007] According to a preferred embodiment of the present application, the rotating speed of the shearing is 3000 rpm ~ 20000 rpm.
[0008] According to a preferred embodiment of the present application, the organic acid comprises oxalic acid and / or glacial acetic acid.
[0009] According to a preferred embodiment of the present application, the time of the calcination I is 0.5 h ~ 2h.
[0010] According to a preferred embodiment of the present application, the time of the calcination II is 1 h ~ 5 h.
[0011] According to a preferred embodiment of the present application, the temperature of the refluxing reaction is 100℃ ~ 130℃.
[0012] According to a preferred embodiment of the present application, the time of the refluxing reaction is 4 h ~ 12h.
[0013] According to a preferred embodiment of the present application, the surfactant comprises at least one of polyvinylpyrrolidone, sodium dodecylsulfate, sodium alginate or sodium dodecylsulfate.
[0014] According to a preferred embodiment of the present application, the time of the shearing is 30 min ~ 180 min.
[0015] According to a preferred embodiment of the present application, the step of the post-treatment comprises washing and spray drying.
[0016] According to a preferred embodiment of the present application, the content of the metal impurities in the single-walled carbon nanotube crude product is 1wt.% ~ 30 wt.%.
[0017] According to a preferred embodiment of the present application, the single-walled carbon nanotube crude product can be prepared by the scheme disclosed in the prior art, for example, by preparing single-walled carbon nanotube crude product through controllable plasma enhanced catalytic pyrolysis.
[0018] The method for purifying single-walled carbon nanotubes according to the embodiments of the present application has at least the following beneficial effects: The present application can improve the purity of single-walled carbon nanotubes, and can realize large-scale production with high purity and high yield without damaging the structure of single-walled carbon nanotubes.
[0019] Other features and advantages of the present application will be set forth in the description that follows, and in part will be apparent from the description, or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS
[0020] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which: Figure 1 is a SEM image of the crude single-walled carbon nanotube prepared; Figure 2 is a SEM image of the single-walled carbon nanotube purified in the embodiment of the present application; Figure 3 is a Raman spectrum of the single-walled carbon nanotube purified in the embodiment of the present application. DETAILED DESCRIPTION
[0021] The following are specific embodiments of the present application, and the technical solutions of the present application are further described in conjunction with the embodiments, but the present application is not limited to these embodiments.
[0022] The reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the technical field unless otherwise specified.
[0023] In some embodiments, the present application provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, the crude single-walled carbon nanotube is first calcined I at 320-450℃, and then calcined II at 280-310℃ to obtain an intermediate I; S2, the intermediate I, a surfactant and water are mixed for shearing dispersion, and after solid-liquid separation, an intermediate II is obtained; S3, the intermediate II and an organic acid are mixed for reflux reaction, and after post-treatment, the single-walled carbon nanotube purified is obtained.
[0024] Thus, the present application can effectively remove amorphous carbon in the single-walled carbon nanotube by twice calcination of the crude single-walled carbon nanotube at a specific temperature, while protecting the single-walled carbon nanotube from being oxidized and decomposed at high temperature. Then, the metal particles in the single-walled carbon nanotube are dispersed by high-speed shearing dispersion in a high-speed homogenizer, and the entanglement of the metal particles and the carbon tube is dispersed, and then the metal impurities are removed by reflux of the organic acid. The purity of the single-walled carbon nanotube is improved, and the structure of the single-walled carbon nanotube is not damaged, realizing large-scale production with high purity and high yield.
[0025] In some embodiments, the rotation speed of the shearing is 3000 rpm ~20000 rpm. For example, the rotation speed of the shearing includes 3000 rpm, 4000 rpm, 5000 rpm, 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm, 10000 rpm, 12000 rpm, 15000 rpm, 16000 rpm, 18000 rpm, 20000 rpm or a sub-range consisting of any two of the above-mentioned values.
[0026] In the present application, in the above-mentioned high rotation speed range, the entanglement of metal particles and carbon nanotubes in single-walled carbon nanotubes is dispersed by shearing force, which is beneficial for subsequent organic acid washing removal.
[0027] In some embodiments, the organic acid includes oxalic acid and / or glacial acetic acid.
[0028] In the present application, the purification method of strong acid and strong oxidizing is abandoned, and the selection of oxalic acid and / or glacial acetic acid can maximize the structural integrity of single-walled carbon nanotubes, and can also effectively reduce the pollution to the environment.
[0029] In some embodiments, the time of the first calcination is 0.5 h ~2h. For example, the time of the first calcination is 0.5h, 1h, 1.5h, 1.8h, 2h or a sub-range consisting of any two of the above-mentioned values. Thus, the calcination time is sufficient, which can avoid the influence of time on the structure of single-walled carbon nanotubes, and can also effectively remove amorphous carbon.
[0030] In some embodiments, the time of the second calcination is 1 h ~5 h. For example, the time of the second calcination is 1h, 1.5h, 2h, 2.5h, 2.5h, 3h, 3.5h, 4h, 5h or a sub-range consisting of any two of the above-mentioned values. Thus, the calcination time is sufficient, which can avoid the influence of time on the structure of single-walled carbon nanotubes, and can also effectively remove amorphous carbon.
[0031] In some embodiments, the reflux temperature is 100℃ ~130℃. For example, the temperature of the reflux reaction is 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃ or a sub-range consisting of any two of the above-mentioned values.
[0032] In some embodiments, the reflux time is 4 h ~12h. For example, the time of the reflux reaction includes 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h or a sub-range consisting of any two of the above-mentioned values.
[0033] In some embodiments, the surfactant comprises at least one of polyvinylpyrrolidone, sodium dodecylsulfate, sodium alginate, or sodium dodecyl sulfate.
[0034] In some embodiments, the shearing time is 30 min ~180 min. For example, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 150 min, 180 min or a sub-range consisting of any two of the aforementioned values.
[0035] In some embodiments, the post-treatment step comprises washing and spray drying.
[0036] In some embodiments, the single-walled carbon nanotube crude product has a metal impurity content of 1 wt.% ~30 wt.%. For example, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, 5 wt.%, 6 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, 25 wt.%, 30 wt.% or a sub-range consisting of any two of the aforementioned values.
[0037] In some embodiments, the single-walled carbon nanotube crude product is prepared by the following method: The single-walled carbon nanotube crude product is prepared by a controllable plasma-enhanced catalytic pyrolysis method. For the specific preparation method, refer to Example 1 of CN2025102906983. Different crude products are classified by inductively coupled plasma optical emission spectrometry (ICP-OES) to detect metal impurities to obtain crude products with different metal impurity contents.
[0038] Example 1 This example provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, pour the prepared 50g single-walled carbon nanotube crude product (metal impurity content 20 wt%) into a tube furnace and calcine at 350℃ for 1h, then reduce to 300℃ and continue to calcine for 2h; S2, after taking out, add 500mL 20 wt% PVP aqueous solution, and use a high-speed homogenizer to shear and disperse at 5000rmp for 1h.
[0039] S3, according to the amount of 600ml glacial acetic acid, use an oil bath pot to reflux at 130℃ for 6h, and keep stirring at 300rpm during the reflux process. After taking out, wash the precipitate with deionized water until it is close to neutral, and spray dry to obtain the purified single-walled carbon nanotubes.
[0040] Example 2 This example provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, pour the prepared 50 g single-walled carbon nanotube crude product (metal impurity content 10.wt%) into a tube furnace and calcine at 350°C for 1 h, then reduce to 300°C and continue to calcine for 2 h; S2, after taking out, add 500 mL 20 wt% PVP aqueous solution, use a high-speed blender to disperse at 3000 rpm for 30 min.
[0041] S3, according to the amount of 600 ml ice acetic acid, use an oil bath pot to reflux at 130°C for 6 h, and keep stirring at 300 rpm during the reflux process. After taking out, wash the precipitate with deionized water until it is close to neutral, and spray dry to obtain the purified single-walled carbon nanotubes.
[0042] Example 3 This example provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, pour the prepared 50 g single-walled carbon nanotube crude product (metal impurity content 20.wt%) into a tube furnace and calcine at 350°C for 1 h, then reduce to 300°C and continue to calcine for 2 h; S2, after taking out, add 500 mL 20 wt% PVP aqueous solution, use a high-speed blender to disperse at 3000 rpm for 30 min.
[0043] S3, according to the amount of 600 ml ice acetic acid, use an oil bath pot to reflux at 130°C for 6 h, and keep stirring at 300 rpm during the reflux process. After taking out, wash the precipitate with deionized water until it is close to neutral, and spray dry to obtain the purified single-walled carbon nanotubes.
[0044] Example 4 This example provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, pour the prepared 50 g single-walled carbon nanotube crude product (metal impurity content 30.wt%) into a tube furnace and calcine at 350°C for 1 h, then reduce to 300°C and continue to calcine for 2 h; S2, after taking out, add 500 mL 20 wt% PVP aqueous solution, use a high-speed blender to disperse at 3000 rpm for 30 min.
[0045] S3, according to the amount of 600 ml ice acetic acid, use an oil bath pot to reflux at 130°C for 6 h, and keep stirring at 300 rpm during the reflux process. After taking out, wash the precipitate with deionized water until it is close to neutral, and spray dry to obtain the purified single-walled carbon nanotubes.
[0046] Example 5 This example provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, pour the prepared 50 g single-walled carbon nanotube crude product (metal impurity content 10.wt%) into a tube furnace and calcine at 350°C for 1 h, then reduce to 300°C and continue to calcine for 2 h; S2, after taking out, add 500 mL 20 wt% PVP aqueous solution, use a high-speed blender to disperse at 5000 rpm for 90 min.
[0047] S3, according to the amount of 600 ml of glacial acetic acid, use an oil bath pot to reflux at 130°C for 6 h, and keep stirring at 300 rpm during the reflux process. After taking out, wash the precipitate with deionized water until it is close to neutral, and spray dry to obtain the purified single-walled carbon nanotubes.
[0048] Example 6 This example provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, pour the prepared 50 g single-walled carbon nanotube crude product (metal impurity content 20.wt%) into a tube furnace and calcine at 350°C for 1 h, then reduce to 300°C and continue to calcine for 2 h; S2, after taking out, add 500 mL 20 wt% PVP aqueous solution, use a high-speed blender to disperse at 5000 rpm for 90 min.
[0049] S3, according to the amount of 600 ml of glacial acetic acid, use an oil bath pot to reflux at 130°C for 6 h, and keep stirring at 300 rpm during the reflux process. After taking out, wash the precipitate with deionized water until it is close to neutral, and spray dry to obtain the purified single-walled carbon nanotubes.
[0050] Example 7 This example provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, pour the prepared 50 g single-walled carbon nanotube crude product (metal impurity content 30.wt%) into a tube furnace and calcine at 350°C for 1 h, then reduce to 300°C and continue to calcine for 2 h; S2, after taking out, add 500 mL 20 wt% PVP aqueous solution, use a high-speed blender to disperse at 5000 rpm for 90 min.
[0051] S3, according to the amount of 600 ml of glacial acetic acid, use an oil bath pot to reflux at 130°C for 6 h, and keep stirring at 300 rpm during the reflux process. After taking out, wash the precipitate with deionized water until it is close to neutral, and spray dry to obtain the purified single-walled carbon nanotubes.
[0052] Example 8 This example provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, pour the prepared 50 g single-walled carbon nanotube crude product (metal impurity content 10.wt%) into a tube furnace and calcine at 350°C for 1 h, then reduce to 300°C and continue to calcine for 2 h; S2, after taking out, add 500 mL of 20 wt% PVP aqueous solution, and use a high-speed blender to shear disperse at 10000 rpm for 180 min.
[0053] S3, according to the amount of 600 ml of glacial acetic acid, use an oil bath pot to reflux at 130°C for 6 h, and keep stirring at 300 rpm during the reflux process. After taking out, wash the precipitate with deionized water until it is close to neutral, and spray dry to obtain the purified single-walled carbon nanotubes.
[0054] Example 9 The example provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, pour the prepared 50 g single-walled carbon nanotube crude product (metal impurity content 20.wt%) into a tube furnace and calcine at 350°C for 1 h, then reduce to 300°C and continue to calcine for 2 h; S2, after taking out, add 500 mL of 20 wt% PVP aqueous solution, and use a high-speed blender to shear disperse at 10000 rpm for 180 min.
[0055] S3, according to the amount of 600 ml of glacial acetic acid, use an oil bath pot to reflux at 130°C for 6 h, and keep stirring at 300 rpm during the reflux process. After taking out, wash the precipitate with deionized water until it is close to neutral, and spray dry to obtain the purified single-walled carbon nanotubes.
[0056] Example 10 The example provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, pour the prepared 50 g single-walled carbon nanotube crude product (metal impurity content 30.wt%) into a tube furnace and calcine at 350°C for 1 h, then reduce to 300°C and continue to calcine for 2 h; S2, after taking out, add 500 mL of 20 wt% PVP aqueous solution, and use a high-speed blender to shear disperse at 10000 rpm for 180 min.
[0057] S3, according to the amount of 600 ml of glacial acetic acid, use an oil bath pot to reflux at 130°C for 6 h, and keep stirring at 300 rpm during the reflux process. After taking out, wash the precipitate with deionized water until it is close to neutral, and spray dry to obtain the purified single-walled carbon nanotubes.
[0058] Comparative Example 1 The comparative example 1 provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, pour the prepared 50 g single-walled carbon nanotube crude product (metal impurity content 30.wt%) into a tube furnace and calcine at 350℃ for 1 h; S2, after taking out, add 500 mL 20 wt% PVP aqueous solution, and use a high-speed blender to shear disperse at 3000 rpm for 30 min.
[0059] S3, according to the amount of 600 ml ice acetic acid, use an oil bath pot to reflux at 130℃ for 6 h, and keep stirring at 300 rpm during the reflux process. After taking out, wash the precipitate with deionized water until it is close to neutral, and spray dry to obtain the purified single-walled carbon nanotube.
[0060] Comparative Example 2 This comparative example 2 provides a method for purifying single-walled carbon nanotubes, comprising the following steps: S1, pour the prepared 50 g single-walled carbon nanotube crude product (metal impurity content 30.wt%) into a tube furnace and calcine at 350℃ for 1 h, and then continue to calcine at 300℃ for 2 h; S2, according to the amount of 600 ml ice acetic acid, use an oil bath pot to reflux at 130℃ for 6 h, and keep stirring at 300 rpm during the reflux process. After taking out, wash the precipitate with deionized water until it is close to neutral, and spray dry to obtain the purified single-walled carbon nanotube.
[0061] Performance test Respectively, the prepared single-walled carbon nanotube crude product and the purified single-walled carbon nanotube (Example 10) were subjected to SEM detection, and the results are shown in Figure 1 and Figure 2 , Figure 1 The granular shape is amorphous carbon wrapped around metal particles, and after the thermal oxidation carbon shell reaction, the metal particles are exposed but still in a tangled state. Figure 2 It is a clean and particle-free single-walled carbon nanotube.
[0062] Further, the single-walled carbon nanotube prepared by the example of the present application was detected by inductively coupled plasma optical emission spectrometry (ICP-OES) for metal content, and the purity was obtained by thermogravimetric (TG) data, and the results are shown in Table 1: Table 1
[0063] Further, the purified single-walled carbon nanotube of Example 10 of the present application was subjected to Raman detection, and the results are shown in Figure 3 As can be seen from the very weak D peak at 1350 on the abscissa, the structural integrity is very good.
[0064] In summary, from the data in Table 1, it can be known that the present application can improve the purity of single-walled carbon nanotubes and realize large-scale production with high purity and high yield by twice calcination of single-walled carbon nanotube crude product at a specific temperature, high-speed shearing dispersion of the single-walled carbon nanotube crude product in a high-speed homogenizer to untangle metal particles in the single-walled carbon nanotube and carbon tubes, and removal of metal impurities through reflux of an organic acid.
[0065] The above is a detailed description in combination with the embodiments of the present application, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge range possessed by those skilled in the art without departing from the purpose of the present application.
Claims
1. A method for purifying single-walled carbon nanotubes, characterized by, The method comprises the following steps: S1, roasting a single-walled carbon nanotube crude product at 320-450 DEG C for the first time (I) and then roasting it at 280-310 DEG C for the second time (II) to obtain an intermediate I; S2, mixing the intermediate I, a surfactant and water to perform shearing dispersion, and then performing solid-liquid separation to obtain an intermediate II; S3, mixing the intermediate II and an organic acid to perform a reflux reaction, and then performing post-treatment to obtain a purified single-walled carbon nanotube.
2. The method of purifying single-walled carbon nanotubes according to claim 1, wherein The rotating speed of the shearing is 3000 rpm-20000 rpm.
3. The method of claim 1, wherein the single-walled carbon nanotubes are purified by the steps of: The organic acid comprises oxalic acid and / or glacial acetic acid. 4. The method of claim 1, wherein the single-walled carbon nanotubes are purified by the steps of: The roasting time I is 0.5 h-2 h. 5. The method of claim 1, wherein the single-walled carbon nanotubes are purified by the steps of: The roasting time II is 1 h-5 h. 6. The method of claim 1, wherein the single-walled carbon nanotubes are purified by the steps of: The reflux reaction temperature is 100 DEG C-130 DEG C.
7. The method of claim 1, wherein the single-walled carbon nanotubes are purified by the steps of: The reflux reaction time is 4 h-12 h. 8. The method of claim 1, wherein the single-walled carbon nanotubes are purified by the steps of: The surfactant comprises at least one of polyvinylpyrrolidone, sodium dodecyl sulfonate, sodium alginate or sodium dodecyl sulfate. 9. The method of claim 1, wherein the single-walled carbon nanotubes are purified by the steps of: The shearing time is 30 min-180 min. 10. The method of claim 1, wherein the single-walled carbon nanotubes are purified by the steps of: The post-treatment step comprises washing and spray drying.