Short carbon nano tube with opening at end part and preparation method of short carbon nano tube

Abstract

The invention discloses a short carbon nanotube with an open end and a preparation method thereof, and belongs to the technical field of preparation of short carbon nanotubes. According to the preparation method, waste plastic is taken as a raw material, nickel and molybdenum loaded aluminum oxide is taken as a catalyst, and the short carbon nanotube with an opening in the end part is prepared by optimizing a catalyst formula, pretreating the raw material and performing a thermal cracking process and accurately controlling the growth of the carbon nanotube. The method provided by the invention is simple and convenient to operate, and does not need complex equipment and high cost; and the synthesized product has stable and uniform quality, is beneficial to large-scale production, and has great application potential in the fields of energy storage, nano electronic device manufacturing and the like.

Description

Technical Field

[0001] The present invention relates to a short carbon nanotube with an open end and a preparation method thereof, belonging to the technical field of short carbon nanotube preparation. Background Art

[0002] As a nanomaterial with a unique structure and excellent properties, the structure of carbon nanotubes can be regarded as being seamlessly curled by graphene sheets. According to the difference in the number of graphene sheets, they are divided into single-walled carbon nanotubes and multi-walled carbon nanotubes. This special microstructure endows carbon nanotubes with many excellent characteristics. In terms of mechanical properties, its tensile strength is extremely high, reaching dozens of times that of steel, while its density is extremely low, making it an ideal reinforcing material in the fields of aerospace, high-end composite materials, etc. From the perspective of electrical properties, carbon nanotubes have excellent electrical conductivity, and some types can even rival metals, showing great application potential in the research and development of electronic devices such as ultra-small transistors and high-performance wires. In terms of thermal properties, carbon nanotubes have extremely high thermal conductivity, showing broad prospects in the field of thermal management materials.

[0003] However, carbon nanotubes face many challenges in practical applications. For example, long carbon nanotubes are extremely prone to agglomeration in the solution system, making it difficult for them to be uniformly dispersed, which greatly limits their applications in fields with high requirements for dispersibility such as biomedicine and coatings. Short carbon nanotubes provide a high density of active sites, making them have extremely wide applications in biopharmaceuticals, catalysis, and energy storage methods. However, the carbon nanotubes prepared by existing preparation technologies have lengths in the micron level and cannot be used as the anode material of lithium batteries. On the other hand, open carbon nanotubes are superior to closed carbon nanotubes in terms of filling and field emission performance. Therefore, developing a method that can stably synthesize short carbon nanotubes with open ends is crucial for expanding the application scope of carbon nanotubes. Summary of the Invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a method for synthesizing short and open carbon nanotubes. By optimizing the catalyst formulation, raw material pretreatment, and pyrolysis process, the growth of carbon nanotubes is precisely controlled to obtain short and open carbon nanotubes that meet various application requirements.

[0005] Technical Solution of the Present Invention:

[0006] One of the purposes of the present invention is to provide a preparation method for short carbon nanotubes with open ends, and the method includes the following steps:

[0007] (1) Mix nickel nitrate powder, ammonium molybdate powder, and aluminum nitrate powder evenly. Add polyethylene glycol 200 to the mixed powder and stir until it becomes a slurry. After standing, place it in a muffle furnace for calcination treatment, naturally cool to room temperature, and grind it into powder to obtain catalyst powder for standby;

[0008] (2) Grind the waste plastics into powder form, add catalyst powder, mix evenly, place the mixed powder in a plastic wrap and fix it into a small ball shape with a high-elasticity rubber band for standby;

[0009] (3) Place the small ball prepared in (2) in a quartz tube, carry out pyrolysis under a nitrogen atmosphere until no gas is released, and cool to room temperature to obtain short carbon nanotubes with open ends.

[0010] Further limit that in (1), nickel nitrate powder, ammonium molybdate powder, and aluminum nitrate powder are mixed according to the molar ratio of nickel, molybdenum, and aluminum of (1-5):0.21:1.

[0011] Further limit that in (1), nickel nitrate powder, ammonium molybdate powder, and aluminum nitrate powder are mixed according to the molar ratio of nickel, molybdenum, and aluminum of 3:0.21:1.

[0012] Further limit that in (1), the mass-volume ratio of the mixed powder to polyethylene glycol 200 is 50 g:5 mL.

[0013] Further limit that in (1), the standing time is 12 h.

[0014] Further limit that in (1), the calcination temperature is 650 °C and the time is 1 h.

[0015] Further limit that in (2), the waste plastics are one or more mixtures of PE, PP, and PS.

[0016] Further limit that in (2), the mass ratio of the waste plastic powder to the catalyst powder is (10-300):100.

[0017] Further limit that in (2), the mass ratio of the waste plastic powder to the catalyst powder is 200:100.

[0018] Further limit that in (3), the pyrolysis temperature is 800 °C and the time is 5-40 min.

[0019] Further limit that in (3), the pyrolysis temperature is 800 °C and the time is 5-15 min.

[0020] The second object of the present invention is to provide a short carbon nanotube with an open end prepared by the above method.

[0021] The third object of the present invention is to provide an application of the above short carbon nanotube with an open end, specifically for energy storage and the manufacture of nanoelectronic devices.

[0022] The beneficial effects of the present invention:

[0023] The present invention uses waste plastics as raw materials, nickel and molybdenum supported on alumina as catalysts, and precisely controls the growth of carbon nanotubes by optimizing the catalyst formulation, raw material pretreatment, and pyrolysis process, to prepare short carbon nanotubes with open ends. Compared with the prior art, it also has the following advantages:

[0024] (1) Using waste plastics as a carbon source can achieve the recycling and reuse of waste plastics, greatly saving energy materials and alleviating the social and ecological pressure.

[0025] (2) Using nickel and molybdenum supported on alumina as a catalyst, it has high catalytic activity, can accelerate the reaction, and precisely regulate the structure of carbon nanotubes. Moreover, this catalyst has good stability, wide raw material sources, and controllable costs, which is conducive to large-scale industrial production of carbon nanotubes.

[0026] (3) The preparation process of the short carbon nanotubes with open ends provided by the present invention has simple steps and low costs, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the Raman comparison spectrum of the carbon nanotubes prepared in Examples 1-5;

[0028] Figure 2 is the TEM photograph (at different magnifications) of the carbon nanotubes prepared in Example 3;

[0029] Figure 3 is the TEM photograph of the carbon nanotubes prepared in Example 10;

[0030] Figure 4 is the TEM photograph of the carbon nanotubes prepared in Example 12;

[0031] Figure 5 is the TEM photograph of the carbon nanotubes prepared in Example 15;

[0032] Figure 6 is the TEM photograph of the carbon nanotubes prepared in Example 16;

[0033] Figure 7 is the TEM photograph of the carbon nanotubes prepared in Example 17;

[0034] Figure 8 is the TEM photograph of the carbon nanotubes prepared in Example 18. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention is provided in conjunction with the embodiments of the specification.

[0036] In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways different from those described herein. Persons skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0037] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation manner of the present invention. The appearances of "in one embodiment" in different places in this specification do not all refer to the same embodiment, nor are they separate or alternative embodiments that are mutually exclusive of other embodiments.

[0038] The experimental methods used in the following embodiments are all conventional methods unless otherwise specified. The materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in this field unless otherwise specified, and persons skilled in the art can obtain them through commercial channels.

[0039] Example 1

[0040] Step 1: The recycled waste plastics are subjected to preliminary cleaning and shearing treatment to obtain waste plastic particles. Among them, the waste plastics are polyethylene (PE) plastics.

[0041] Step 2: Prepare the catalyst. Select nickel nitrate, ammonium molybdate, and aluminum nitrate as raw materials. First, put them into a high-speed grinder and grind them into powder form. According to the molar ratio of nickel, molybdenum, and aluminum of 1:0.21:1, accurately weigh the corresponding mass of the powder and place it in a mortar for further grinding and mixing evenly. Subsequently, add an appropriate amount of polyethylene glycol 200 (the specific addition amount of polyethylene glycol 200 is 10% of the mixed powder), and stir until it forms a slurry. Let the mixture stand for 12 h, put it into a muffle furnace, and calcine it at a high temperature of 650 °C for 1 h. After the calcination is completed, take it out and cool it naturally to room temperature, and then grind it into powder again and collect it for standby.

[0042] Step 3: Grind the PE particles pretreated in Step 1 into powder form in a high-speed grinder; weigh 100 g of PE powder and 200 g of catalyst powder and grind them finely and mix them evenly in a mortar; take 10 g of the above-mentioned mixed powder and place it in a plastic wrap, and fix it into a small ball shape with a high-elasticity rubber band for standby.

[0043] Step 4: Place the prepared small balls into a quartz tube and introduce nitrogen to purge air for 20 min. While purging air, heat the tube furnace to 800 °C. After purging air, put the quartz tube into the tube furnace and, under continuous protection of nitrogen, carry out a pyrolysis reaction on the mixture at 800 °C until no gas is released. Take out the quartz tube and let it cool naturally to room temperature to successfully obtain a carbon-containing product. Put the carbon product into a self-sealing bag for weighing. The obtained product is named CNTs-1.

[0044] Example 2

[0045] The difference between this example and Example 1 lies in that: in Step 2, the molar ratio of nickel, molybdenum, and aluminum is 2:0.21:1, and the remaining process steps and parameter settings are the same as those in Example 1. A carbon-containing product is obtained, and the obtained product is named CNTs-2.

[0046] Example 3

[0047] The difference between this example and Example 1 lies in that: in Step 2, the molar ratio of nickel, molybdenum, and aluminum is 3:0.21:1, and the remaining process steps and parameter settings are the same as those in Example 1. A carbon-containing product is obtained, and the obtained product is named CNTs-3.

[0048] Example 4

[0049] The difference between this example and Example 1 lies in that: in Step 2, the molar ratio of nickel, molybdenum, and aluminum is 4:0.21:1, and the remaining process steps and parameter settings are the same as those in Example 1. A carbon-containing product is obtained, and the obtained product is named CNTs-4.

[0050] Example 5

[0051] The difference between this example and Example 1 lies in that: in Step 2, the molar ratio of nickel, molybdenum, and aluminum is 5:0.21:1, and the remaining process steps and parameter settings are the same as those in Example 1. A carbon-containing product is obtained, and the obtained product is named CNTs-5.

[0052] Example 6

[0053] The difference between this example and Example 1 lies in that: in Step 2, the molar ratio of nickel, molybdenum, and aluminum is 3:0.07:1, and the remaining process steps and parameter settings are the same as those in Example 1. A carbon-containing product is obtained, and the obtained product is named CNTs-6.

[0054] Example 7

[0055] The difference between this example and Example 1 lies in that: in Step 2, the molar ratio of nickel, molybdenum, and aluminum is 3:0.14:1, and the remaining process steps and parameter settings are the same as those in Example 1. A carbon-containing product is obtained, and the obtained product is named CNTs-7.

[0056] Example 8

[0057] The difference between this example and Example 1 is that in Step 2, the molar ratio of nickel, molybdenum, and aluminum is 3:0.28:1. The remaining process steps and parameter settings are the same as those in Example 1, and a carbon-containing product is obtained. The obtained product is named CNTs-8.

[0058] Example 9

[0059] The difference between this example and Example 1 is that in Step 2, the molar ratio of nickel, molybdenum, and aluminum is 3:0.35:1. The remaining process steps and parameter settings are the same as those in Example 1, and a carbon-containing product is obtained. The obtained product is named CNTs-9.

[0060] Example 10

[0061] The difference between this example and Example 3 is that in Step 3, the mass ratio of PE powder to catalyst powder is 100 g:10 g. The remaining process steps and parameter settings are the same as those in Example 1, and a carbon-containing product is obtained. The obtained product is named CNTs-10.

[0062] Example 11

[0063] The difference between this example and Example 3 is that in Step 3, the mass ratio of PE powder to catalyst powder is 100 g:50 g. The remaining process steps and parameter settings are the same as those in Example 1, and a carbon-containing product is obtained. The obtained product is named CNTs-11.

[0064] Example 12

[0065] The difference between this example and Example 3 is that in Step 3, the mass ratio of PE powder to catalyst powder is 100 g:100 g. The remaining process steps and parameter settings are the same as those in Example 1, and a carbon-containing product is obtained. The obtained product is named CNTs-12.

[0066] Example 13

[0067] The difference between this example and Example 3 is that in Step 3, the mass ratio of PE powder to catalyst powder is 100 g:150 g. The remaining process steps and parameter settings are the same as those in Example 1, and a carbon-containing product is obtained. The obtained product is named CNTs-13.

[0068] Example 14

[0069] The difference between this example and Example 3 is that in Step 3, the mass ratio of PE powder to catalyst powder is 100 g:250 g. The remaining process steps and parameter settings are the same as those in Example 1, and a carbon-containing product is obtained. The obtained product is named CNTs-14.

[0070] Example 15

[0071] The difference between this example and Example 3 is that: in Step 3, the mass ratio of PE powder to catalyst powder is 100 g: 300 g, and the remaining process steps and parameter settings are the same as those in Example 1. A carbon-containing product is obtained and the obtained product is named CNTs-15.

[0072] Example 16

[0073] The difference between this example and Example 3 is that: in Step 1, the waste plastic is polypropylene (PP) plastic, and the remaining process steps and parameter settings are the same as those in Example 1. A carbon-containing product is obtained and the obtained product is named CNTs-16.

[0074] Example 17

[0075] The difference between this example and Example 3 is that: in Step 1, the waste plastic is polystyrene (PS) plastic, and the remaining process steps and parameter settings are the same as those in Example 1. A carbon-containing product is obtained and the obtained product is named CNTs-17.

[0076] Example 18

[0077] The difference between this example and Example 3 is that: in Step 1, the waste plastic is a mixture of PE, PP, and PS with a mass ratio of 1:1:1, and the remaining process steps and parameter settings are the same as those in Example 1. A carbon-containing product is obtained and the obtained product is named CNTs-18.

[0078] Effect Example

[0079] (1) The yields of the carbon nanotubes prepared in the above Example 3 and Examples 6-9 were characterized, and the results are shown in Table 1 below.

[0080] Table 1

[0081]

[0082] As can be seen from Table 1 above, as the Mo content of the catalyst increases, the yield of carbon nanotubes first increases and then decreases. It can be seen that the yield is the highest when the catalyst ratio is 3:0.21:1, and this ratio is determined.

[0083] (2) Raman was used to characterize the carbon nanotubes prepared in Examples 1-5, and the comparison spectra are as Figure 1 shown. All five groups of carbon nanotubes showed three obvious vibration peaks, located at 1350 cm -1 , 1580 cm -1 and 2700 cm -1, corresponding to the D peak, G peak, and 2D peak. The D peak reflects the degree of disorder in the carbon nanotube structure, indicating defects in the carbon structure and the disorder of the s hybridization vibration of carbon atoms. p2 The G peak reflects the degree of order in the carbon nanotube structure and corresponds to the E2g mode of hexagonal graphite in the graphite layer of the system. The 2D peak is the second-order Raman peak of two-phonon resonance, further reflecting the quality and purity of the carbon nanotubes. The ratio of the peak intensities of the G peak to the D peak (I G / I D ) is proportional to the graphitization degree of the carbon nanotubes. The larger the ratio of I G / I D , the higher the graphitization degree of the carbon nanotubes, the less amorphous carbon, and the fewer structural defects. In the figure, the ratios of I G / I D of the carbon nanotubes are relatively large. With the increase of the Ni content in the catalyst, the ratio of I G / I D first increases and then decreases, and they all have sharp 2D peaks. Raman shows that the carbon nanotubes prepared in Example 3 have a higher graphitization degree and fewer defects.

[0084] (3) Characterize the microscopic morphology of the carbon nanotubes prepared in Examples 3, 10, 12, and Examples 15 - 18, and the results are as Figures 2 to 8 shown. It can be Figure 2 seen that the length of CNTs-3 prepared in Example 3 is 100 - 400 nm. The enlarged view of the end shows that it has an open structure and is relatively loosely distributed. The morphology shows carbon nanotubes with significant length differences and uneven diameters. Figures 3 - 5 The results show that the length range of CNTs-10 prepared in Example 10 is 10 - 20 μm, with a long tubular structure and an aggregated distribution; the length of CNTs-12 prepared in Example 12 is 200 - 1000 nm; the length of CNTs-15 prepared in Example 15 is 200 - 1200 nm. By comparison, it is found that the lengths of the carbon nanotubes prepared in Examples 12 and 15 are between those of Example 10 and Example 3, indicating that with the increase of the catalyst content, the length of the carbon nanotubes shows a trend of first shortening and then lengthening. Among them, the length of the product obtained in Example 3 is the shortest and both ends are open. Figures 6 - 8 It is shown that the length distribution of CNTs-16 prepared in Example 16 is uneven, with the main range being 50 - 1000 nm and there are a small number of ultra-long carbon nanotubes; the length of CNTs-17 prepared in Example 17 is 50 - 400 nm and shows an aggregated state distribution; CNTs-18 prepared in Example 18 has a similar morphology to CNTs-16, with the main length being 100 - 800 nm and accompanied by a small number of long tube structures. Although different carbon sources are used in Examples 16 - 18, relatively short carbon nanotubes can be prepared.

[0085] The above results show that by regulating the ratio of the catalyst to the carbon source, the length and microscopic morphological characteristics of the carbon nanotubes can be effectively regulated. The above is only the preferred embodiment of the present invention. In view of the fact that those skilled in the art of the present invention can make appropriate changes and modifications to the above embodiments, therefore, the present invention is not limited to the specific embodiments described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing short carbon nanotubes with an open end, characterized in that, Including: (1) Mix nickel nitrate powder, ammonium molybdate powder, and aluminum nitrate powder evenly. Add polyethylene glycol 200 to the mixed powder and stir until it becomes a slurry. After standing, place it in a muffle furnace for calcination treatment, cool it naturally to room temperature, and grind it into powder to obtain catalyst powder for standby; (2) Grind waste plastics into powder form, add the catalyst powder, and mix evenly. Place the mixed powder in a plastic wrap and fix it into a small ball shape with a high-elasticity rubber band for standby; (3) Place the small ball prepared in (2) in a quartz tube and carry out pyrolysis under a nitrogen atmosphere until no gas is released, and then cool it to room temperature to obtain short carbon nanotubes with open ends; 2. The preparation method according to claim 1, characterized in that, (1) The nickel nitrate powder, ammonium molybdate powder, and aluminum nitrate powder are mixed according to the molar ratio of nickel, molybdenum, and aluminum of (1-5):0.21:1; 3. The preparation method according to claim 2, characterized in that, (1) The nickel nitrate powder, ammonium molybdate powder, and aluminum nitrate powder are mixed according to the molar ratio of nickel, molybdenum, and aluminum of 3:0.21:1; 4. The preparation method according to claim 1, characterized in that, (1) The mass-volume ratio of the mixed powder to polyethylene glycol 200 is 50g:5mL; 5. The preparation method according to claim 1, wherein (1) The calcination temperature is 650°C and the time is 1h; 6. The preparation method according to claim 1, wherein (2) The waste plastics are one or more mixtures of PE, PP, and PS; the mass ratio of the waste plastic powder to the catalyst powder is (10-300):100; 7. The preparation method according to claim 6, characterized in that, (2) The mass ratio of the waste plastic powder to the catalyst powder is 200:100; 8. The preparation method according to claim 1, characterized in that, (3) The pyrolysis temperature is 800°C and the time is 5-40min; 9. Short carbon nanotubes with open ends prepared by the method according to any one of claims 1-8; 10. Use of the short carbon nanotube with an open end according to claim 9, characterized in that, For electrocatalytic reactions, energy storage, and the manufacture of nanoelectronic devices.

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