A method for efficiently preparing multi-walled carbon nanotubes by using natural gas as a carbon source

Abstract

The present application relates to the technical field of multi-walled carbon nanotube preparation, and discloses a method for efficiently preparing multi-walled carbon nanotubes by taking natural gas as a carbon source, which comprises the following steps: dissolving ferrocene, chloride and sublimed sulfur in an organic solvent to obtain a bimetallic catalyst precursor after ultrasonic treatment; using a needle tube to take the bimetallic catalyst precursor, and installing the needle tube on a syringe pump; starting a preheating device and a tubular furnace to a set temperature, under an inert atmosphere, starting the syringe pump to inject the bimetallic catalyst precursor in the needle tube into the tubular furnace, and introducing hydrogen and a carbon source to perform a reaction to obtain multi-walled carbon nanotubes; when the injection of the bimetallic catalyst precursor is completed, stopping the introduction of the inert gas, hydrogen and the carbon source, and collecting the multi-walled carbon nanotubes in a collecting device. The present application uses the above steps, and significantly improves the conversion efficiency of the carbon source into multi-walled carbon nanotubes by using a bimetallic catalyst, thereby opening up new possibilities for the commercial production of carbon nanotubes.

Description

Technical Field

[0001] This invention relates to the field of multi-walled carbon nanotube preparation technology, and in particular to a method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source. Background Technology

[0002] Carbon nanotubes, as a representative one-dimensional nanomaterial, have attracted much attention due to their outstanding flexibility and excellent electrical conductivity. In the preparation of carbon nanotubes, natural gas has significant advantages over traditional carbon sources (such as methane, ethylene, propylene, and ethanol). First, natural gas has large global reserves and is easy to obtain and transport, thus using natural gas as a raw material helps reduce raw material costs. Second, in the new energy industry, natural gas is both an important energy supply source and a fundamental raw material for synthesizing advanced materials such as carbon nanotubes; this dual role facilitates the synergistic optimization of upstream and downstream industries.

[0003] However, using natural gas as a carbon source for carbon nanotube preparation presents several significant challenges. As a relatively inert raw material, natural gas typically exhibits unsatisfactory yields and conversion efficiencies in its conversion to carbon nanotubes, making efficient utilization difficult. Furthermore, producing high-quality carbon nanotubes suitable for lithium-ion battery applications through catalytic cracking of natural gas is quite challenging, often encountering technical difficulties such as uneven nanotube diameters and irregular morphologies. Summary of the Invention

[0004] The purpose of this invention is to provide a method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source, which solves the problems of low yield, uneven diameter, and irregular morphology of multi-walled carbon nanotubes produced by using natural gas as an inert carbon source.

[0005] To achieve the above objectives, this invention provides a method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source, comprising the following steps:

[0006] S1. Ferrocene, chloride and sublimed sulfur are dissolved in an organic solvent and ultrasonicated to obtain a bimetallic catalyst precursor.

[0007] S2. Use a syringe to take the bimetallic catalyst precursor prepared in S1 and install the syringe on the injection pump.

[0008] S3. Start the preheating device and tube furnace to the set temperature. Under an inert atmosphere, start the injection pump to inject the bimetallic catalyst precursor in the syringe into the tube furnace. Introduce hydrogen and carbon source to react and obtain multi-walled carbon nanotubes.

[0009] S4. After the bimetallic catalyst precursor is injected, stop the flow of inert gas, hydrogen and carbon source, and collect multi-walled carbon nanotubes in the collection device.

[0010] Preferably, in S1, the mass ratio of ferrocene to sublimed sulfur is 1:0.01-0.1, and the mass ratio of chloride to ferrocene is 1:1-5.

[0011] Preferably, in S1, the chloride is a metal chloride, including one or more of copper chloride, nickel chloride, cobalt chloride, mercuric chloride, and ruthenium chloride. The chloride can be reduced to a metal in a hydrogen atmosphere, forming metal nanoparticles on the bimetallic catalyst.

[0012] Preferably, in S1, the organic solvent includes one or more of xylene, toluene, ethylbenzene, n-hexane, and isooctane.

[0013] Preferably, in S1, the ultrasound time is 5-20 min.

[0014] Preferably, in S3, the inert atmosphere includes one or more of nitrogen and argon.

[0015] Preferably, in step S3, the preheating device is set to a temperature of 50-500°C, and the tube furnace is set to a temperature of 600-1400°C. Bimetallic catalyst nanoparticles are formed in the tube furnace.

[0016] Preferably, in S3, the flow rate of the inert gas is 10 sccm-2 slm, the flow rate of the hydrogen gas is 10 sccm-2 slm, and the flow rate of the carbon source is 10 sccm-1 slm.

[0017] Preferably, in S3, the carbon source is natural gas.

[0018] Preferably, in step S3, the injection rate of the injection pump is 0.01-20 ml / min to maintain the activity of the obtained bimetallic catalyst nanoparticles.

[0019] The multi-walled carbon nanotubes prepared by the above method have a diameter of 40-80 nm, a length of 10-25 μm, and a specific surface area of ​​70-110 m². 2 / g, bulk density is 0.03-0.05g / cm³ 3 .

[0020] The mechanism of this invention is as follows:

[0021] This invention first prepares a bimetallic catalyst precursor, and then obtains the bimetallic catalyst in a tube furnace. The bimetallic catalyst has more active sites to catalyze the cracking of natural gas. Carbon free radicals are incorporated into the bimetallic catalyst to precipitate multi-walled carbon nanotubes. The bimetallic catalyst can avoid migration and aggregation and increase the amount of carbon melted.

[0022] Therefore, the beneficial effects of the above steps in this invention are as follows:

[0023] 1. The preparation method provided by the present invention is simple to operate and low in cost. Under the same process conditions, it significantly improves the yield of multi-walled carbon nanotubes produced by natural gas as an inert carbon source. The multi-walled carbon nanotubes obtained have uniform diameter and regular morphology.

[0024] 2. The bimetallic catalyst precursor obtained in this invention is used to obtain a bimetallic alloy catalyst in a tube furnace. This bimetallic alloy catalyst is not easily deactivated and can effectively catalyze the cracking of natural gas, thereby growing multi-walled carbon nanotubes.

[0025] 3. The multi-walled carbon nanotubes prepared by the preparation method provided by the present invention have complete structures, high crystallinity, uniform diameter in the range of 50-60 nm;

[0026] 4. The preparation method provided by this invention significantly improves the conversion efficiency of carbon source into multi-walled carbon nanotubes, opening up new possibilities for the commercial production of carbon nanotubes.

[0027] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the preparation process of multi-walled carbon nanotubes in Embodiment 1 of the present invention;

[0029] Figure 2 This is a scanning electron microscope image of the multi-walled carbon nanotubes in Embodiment 1 of the present invention;

[0030] Figure 3 This is a transmission electron microscope image of the multi-walled carbon nanotubes in Embodiment 1 of the present invention;

[0031] Figure 4 This is a statistical diagram of the diameter of multi-walled carbon nanotubes in Embodiment 1 of the present invention;

[0032] Figure 5 This is a length statistics diagram of the multi-walled carbon nanotubes in Embodiment 1 of the present invention;

[0033] Figure 6 This is a scanning electron microscope image of the multi-walled carbon nanotubes in Embodiment 2 of the present invention;

[0034] Figure 7 This is a statistical chart of the diameters of multi-walled carbon nanotubes in Embodiment 2 of the present invention;

[0035] Figure 8 This is a length statistics diagram of the multi-walled carbon nanotubes in Embodiment 2 of the present invention;

[0036] Figure 9 This is a scanning electron microscope image of the multi-walled carbon nanotubes in Embodiment 3 of the present invention;

[0037] Figure 10This is a statistical chart of the diameters of multi-walled carbon nanotubes in Embodiment 3 of the present invention;

[0038] Figure 11 This is a length statistics diagram of the multi-walled carbon nanotubes in Embodiment 3 of the present invention;

[0039] Figure 12 This is a scanning electron microscope image of the multi-walled carbon nanotubes in Embodiment 4 of the present invention;

[0040] Figure 13 This is a statistical chart of the diameters of multi-walled carbon nanotubes in Embodiment 4 of the present invention;

[0041] Figure 14 This is a length statistics diagram of the multi-walled carbon nanotubes in Embodiment 4 of the present invention;

[0042] Figure 15 This is a scanning electron microscope image of the multi-walled carbon nanotubes in Embodiment 5 of the present invention;

[0043] Figure 16 This is a statistical diagram of the diameter of multi-walled carbon nanotubes in Embodiment 5 of the present invention;

[0044] Figure 17 This is a length statistics diagram of the multi-walled carbon nanotubes in Embodiment 5 of the present invention. Detailed Implementation

[0045] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0046] The present invention will be explained in more detail through the following embodiments. The purpose of disclosing the present invention is to protect all changes and modifications within the scope of the present invention. The present invention is not limited to the following embodiments.

[0047] Example 1

[0048] A method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source, such as Figure 1 As shown,

[0049] S1. Weigh ferrocene, copper chloride and sublimed sulfur according to the mass ratio of ferrocene to sublimed sulfur as 1:0.02 and copper chloride to ferrocene as 1:1. Dissolve ferrocene, copper chloride and sublimed sulfur in xylene and sonicate for 10 min to obtain the bimetallic catalyst precursor.

[0050] S2. Use a syringe to take the bimetallic catalyst precursor prepared in S1 and attach the syringe to the injection pump.

[0051] S3. Start the preheating device and tube furnace to the set temperatures. The set temperature of the preheating device is 400℃, and the set temperature of the tube furnace is 1000℃. Under an argon atmosphere with an argon flow rate of 500 sccm, start the injection pump to inject the bimetallic catalyst precursor from the syringe into the tube furnace at an injection rate of 5 ml / min. Introduce hydrogen and natural gas to react and obtain multi-walled carbon nanotubes.

[0052] In S3, the flow rate of hydrogen is 1 slm and the flow rate of natural gas is 50 sccm.

[0053] S4. After the bimetallic catalyst precursor is injected, stop the flow of argon, hydrogen and natural gas, and collect the multi-walled carbon nanotubes in the collection device.

[0054] The scanning electron microscope image of the multi-walled carbon nanotubes obtained in this embodiment is as follows: Figure 2 As shown, the transmission electron microscope image is as follows. Figure 3 As shown in the figure, the pipe diameter and length statistics are as follows: Figure 4-5 As shown.

[0055] Example 2

[0056] A method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source.

[0057] S1. Weigh ferrocene, nickel chloride and sublimed sulfur according to the mass ratio of ferrocene to sublimed sulfur as 1:0.02 and nickel chloride to ferrocene as 1:1. Dissolve ferrocene, nickel chloride and sublimed sulfur in xylene and sonicate for 10 min to obtain the bimetallic catalyst precursor.

[0058] S2. Use a syringe to take the bimetallic catalyst precursor prepared in S1 and attach the syringe to the injection pump.

[0059] S3. Start the preheating device and tube furnace to the set temperatures. The set temperature of the preheating device is 400℃, and the set temperature of the tube furnace is 1000℃. Under an argon atmosphere with an argon flow rate of 500 sccm, start the injection pump to inject the bimetallic catalyst precursor from the syringe into the tube furnace at an injection rate of 5 ml / min. Introduce hydrogen and natural gas to react and obtain multi-walled carbon nanotubes.

[0060] In S3, the flow rate of hydrogen is 1 slm and the flow rate of natural gas is 50 sccm.

[0061] S4. After the bimetallic catalyst precursor is injected, stop the flow of argon, hydrogen and natural gas, and collect the multi-walled carbon nanotubes in the collection device.

[0062] The scanning electron microscope image of the multi-walled carbon nanotubes obtained in this embodiment is as follows: Figure 6As shown in the figure, the pipe diameter and length statistics are as follows: Figure 7-8 As shown.

[0063] Example 3

[0064] A method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source.

[0065] S1. Weigh ferrocene, cobalt chloride and sublimed sulfur according to the mass ratio of ferrocene to sublimed sulfur as 1:0.02 and cobalt chloride to ferrocene as 1:1. Dissolve ferrocene, cobalt chloride and sublimed sulfur in xylene and sonicate for 10 min to obtain the bimetallic catalyst precursor.

[0066] S2. Use a syringe to take the bimetallic catalyst precursor prepared in S1 and attach the syringe to the injection pump.

[0067] S3. Start the preheating device and tube furnace to the set temperatures. The set temperature of the preheating device is 400℃, and the set temperature of the tube furnace is 1000℃. Under an argon atmosphere with an argon flow rate of 500 sccm, start the injection pump to inject the bimetallic catalyst precursor from the syringe into the tube furnace at an injection rate of 5 ml / min. Introduce hydrogen and natural gas to react and obtain multi-walled carbon nanotubes.

[0068] In S3, the flow rate of hydrogen is 1 slm and the flow rate of natural gas is 50 sccm.

[0069] S4. After the bimetallic catalyst precursor is injected, stop the flow of argon, hydrogen and natural gas, and collect the multi-walled carbon nanotubes in the collection device.

[0070] The scanning electron microscope image of the multi-walled carbon nanotubes obtained in this embodiment is as follows: Figure 9 As shown in the figure, the statistical chart of pipe diameter and length is as follows: Figure 10-11 As shown.

[0071] Example 4

[0072] A method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source.

[0073] S1. Weigh ferrocene, ruthenium chloride and sublimed sulfur according to the mass ratio of ferrocene to sublimed sulfur as 1:0.02 and the mass ratio of ruthenium chloride to ferrocene as 1:1. Dissolve ferrocene, ruthenium chloride and sublimed sulfur in xylene and sonicate for 10 min to obtain the bimetallic catalyst precursor.

[0074] S2. Use a syringe to take the bimetallic catalyst precursor prepared in S1 and attach the syringe to the injection pump.

[0075] S3. Start the preheating device and tube furnace to the set temperatures. The set temperature of the preheating device is 400℃, and the set temperature of the tube furnace is 1000℃. Under an argon atmosphere with an argon flow rate of 500 sccm, start the injection pump to inject the bimetallic catalyst precursor from the syringe into the tube furnace at an injection rate of 5 ml / min. Introduce hydrogen and natural gas to react and obtain multi-walled carbon nanotubes.

[0076] In S3, the flow rate of hydrogen is 1 slm and the flow rate of natural gas is 50 sccm.

[0077] S4. After the bimetallic catalyst precursor is injected, stop the flow of argon, hydrogen and natural gas, and collect the multi-walled carbon nanotubes in the collection device.

[0078] The scanning electron microscope image of the multi-walled carbon nanotubes obtained in this embodiment is as follows: Figure 12 As shown in the figure, the statistical chart of pipe diameter and length is as follows: Figure 13-14 As shown.

[0079] Example 5

[0080] A method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source.

[0081] S1. Weigh ferrocene, mercuric chloride and sublimed sulfur according to the mass ratio of ferrocene to sublimed sulfur as 1:0.02 and mercuric chloride to ferrocene as 1:1. Dissolve ferrocene, mercuric chloride and sublimed sulfur in xylene and sonicate for 10 min to obtain the bimetallic catalyst precursor.

[0082] S2. Use a syringe to take the bimetallic catalyst precursor prepared in S1 and attach the syringe to the injection pump.

[0083] S3. Start the preheating device and tube furnace to the set temperatures. The set temperature of the preheating device is 400℃, and the set temperature of the tube furnace is 1000℃. Under an argon atmosphere with an argon flow rate of 500 sccm, start the injection pump to inject the bimetallic catalyst precursor from the syringe into the tube furnace at an injection rate of 5 ml / min. Introduce hydrogen and natural gas to react and obtain multi-walled carbon nanotubes.

[0084] In S3, the flow rate of hydrogen is 1 slm and the flow rate of natural gas is 50 sccm.

[0085] S4. After the bimetallic catalyst precursor is injected, stop the flow of argon, hydrogen and natural gas, and collect the multi-walled carbon nanotubes in the collection device.

[0086] The scanning electron microscope image of the multi-walled carbon nanotubes obtained in this embodiment is as follows: Figure 15 As shown in the figure, the statistical chart of pipe diameter and length is as follows: Figure 16-17 As shown.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source, characterized in that: Includes the following steps, S1. Ferrocene, chloride and sublimed sulfur are dissolved in an organic solvent and ultrasonicated to obtain a bimetallic catalyst precursor. S2. Use a syringe to take the bimetallic catalyst precursor prepared in S1 and install the syringe on the injection pump. S3. Start the preheating device and tube furnace to the set temperature. Under an inert atmosphere, start the injection pump to inject the bimetallic catalyst precursor in the syringe into the tube furnace. Introduce hydrogen and carbon source to react and obtain multi-walled carbon nanotubes. S4. After the bimetallic catalyst precursor is injected, stop the flow of inert gas, hydrogen and carbon source, and collect multi-walled carbon nanotubes in the collection device. In S1, the mass ratio of ferrocene to sublimed sulfur is 1:0.01-0.1, and the mass ratio of chloride to ferrocene is 1:1-5. In S1, the chloride is a metal chloride, including one or more of copper chloride, nickel chloride, cobalt chloride, mercuric chloride, and ruthenium chloride; In S1, the organic solvent includes one or more of xylene, toluene, ethylbenzene, n-hexane, and isooctane.

2. The method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source according to claim 1, characterized in that: In S3, the inert atmosphere includes one or more of nitrogen and argon.

3. The method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source according to claim 1, characterized in that: In S3, the preheating device is set to a temperature of 50-500℃, and the tubular furnace is set to a temperature of 600-1400℃.

4. The method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source according to claim 1, characterized in that: In S3, the flow rate of the inert gas is 10 sccm-2 slm, the flow rate of the hydrogen gas is 10 sccm-2 slm, and the flow rate of the carbon source is 10 sccm-1 slm.

5. The method for efficiently preparing multi-walled carbon nanotubes using natural gas as a carbon source according to claim 1, characterized in that: In S3, the injection rate of the syringe pump is 0.01-20 ml / min.

6. A multi-walled carbon nanotube prepared using the method according to any one of claims 1-5, characterized in that: Multi-walled carbon nanotubes have a diameter of 40-80 nm, a length of 10-25 μm, and a specific surface area of ​​70-110 m². 2 / g, bulk density is 0.03-0.05g / cm³ 3 .

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