Preparation method and application of single-walled carbon nanotube

Abstract

The invention discloses a preparation method of a single-walled carbon nanotube, which comprises the following steps: (1) annealing a quartz substrate to obtain a pretreated substrate; (2) putting a catalyst precursor and an accelerant into the pretreated substrate, putting the pretreated substrate into a constant-temperature area of a tubular furnace, introducing protective gas, raising the temperature to 600-800 DEG C in the atmosphere of the protective gas, and keeping the constant temperature for 6-10 minutes; (3) hydrogen is preheated, the preheated hydrogen is introduced into the tubular furnace, the temperature is increased to 800-1000 DEG C, and heat preservation is conducted for 6-10 min; and (4) preheating the carbon source gas, introducing the carbon source gas into the tubular furnace, preserving heat for 20-30 minutes at the temperature of 800-1000 DEG C, stopping conveying the hydrogen and the carbon source gas, cooling to 180-220 DEG C, stopping conveying the protective gas, introducing air, cooling, and collecting a product to obtain the single-walled carbon nanotube. According to the preparation method of the single-walled carbon nanotube, the tube diameter of the single-walled carbon nanotube is 1-3 nm, the carbon yield is larger than 12%, the single-walled carbon nanotube can be produced in batches, and the single-walled carbon nanotube is used for preparing carbon nanotube conductive paste.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon nanotubes, and in particular relates to a preparation method and application of single-walled carbon nanotubes. Background Art

[0002] Single-walled carbon nanotubes are a new type of functional material with a one-dimensional tubular molecular structure. With its special structure, it shows extremely strong quantum effects and unique physical and chemical properties. It has shown great potential for application in many fields such as catalysis, composite materials, energy storage materials and microelectronic devices. Due to the different chirality and diameter of single-walled carbon nanotubes, their electrical properties vary, showing two electrical properties: semiconductor and metallic. How to obtain single-walled carbon nanotubes with higher purity is of great significance for practical applications.

[0003] The preparation methods of single-walled carbon nanotubes are as follows: The current preparation methods of single-walled carbon nanotubes mainly include direct current arc method, floating catalytic method, plasma arc method, carbon nanotube array method, fluidized bed CVD method, electric explosion, combustion method, etc. The carbon content of single-walled carbon nanotubes prepared by arc method is high, and the carbon nanotubes prepared by floating catalysis have high product quality, but low yield. How to improve the carbon yield of single-walled carbon nanotubes and the daily kilogram-level output has become a key factor affecting the large-scale preparation of single-walled carbon nanotubes. Summary of the invention

[0004] In view of this, the present invention provides a preparation method and application of single-walled carbon nanotubes to solve the above-mentioned problems.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing single-walled carbon nanotubes comprises the following steps:

[0007] (1) annealing the quartz substrate to obtain a pretreated substrate;

[0008] (2) placing a catalyst precursor and a promoter in a pretreated substrate, placing the substrate in a constant temperature zone of a tube furnace, introducing a protective gas, heating the substrate at a rate of 10 to 20° C. / min to 600 to 800° C. in a protective gas atmosphere, and maintaining the temperature for 6 to 10 minutes;

[0009] (3) preheating the hydrogen, introducing the preheated hydrogen into the tubular furnace, and simultaneously raising the temperature to 800-1000° C. at a heating rate of 10-20° C. / min, and keeping the temperature for 6-10 min;

[0010] (4) Preheating the carbon source gas, introducing the carbon source gas into the tubular furnace, maintaining the temperature at 800-1000°C for 20-30 minutes, stopping the supply of hydrogen and carbon source gas, cooling to 180-220°C, stopping the supply of protective gas, introducing air and cooling to room temperature, taking out the substrate to collect the product, and obtaining single-walled carbon nanotubes.

[0011] Furthermore, the method for annealing the quartz substrate in step (1) comprises the following steps:

[0012] The quartz substrate was cleaned with deionized water, acetone, ethanol and deionized water ultrasonically for 40 to 60 minutes in sequence, and then blown dry with a nitrogen gun. The dried quartz substrate was neatly placed in a crucible with the front side facing up and placed in a muffle furnace. The temperature was raised to 850 to 950° C. in an oxygen atmosphere and kept warm for 8 to 12 hours, then cooled to 200 to 300° C., air was introduced and naturally cooled to room temperature to obtain a pretreated substrate.

[0013] Furthermore, the ultrasonic cleaning conditions are a frequency of 80 to 100 kHz and a power of 400 to 800 W.

[0014] Furthermore, the catalyst precursor in step (2) is at least one of tungsten oxide, tungsten sulfide, molybdenum oxide and molybdenum sulfide.

[0015] Furthermore, the accelerator in step (2) is at least one of sulfur powder, carbon disulfide, mercaptan and thiophene.

[0016] Furthermore, the protective gas in step (2) is at least one of nitrogen, helium and argon, and the flow rate of the protective gas is 800 to 1000 cm 3 / min.

[0017] Furthermore, in step (3), the preheating temperature of the hydrogen is 600-800°C, and the flow rate of the hydrogen is 400-600cm 3 / min.

[0018] Furthermore, the carbon source gas in step (4) is at least one of methane, ethylene and acetylene, the preheating temperature of the carbon source gas is 600-800°C, and the flow rate of the carbon source gas is 600-800cm / s. 3 / min.

[0019] Furthermore, the diameter of the single-walled carbon nanotubes in step (4) is 1 to 3 nm.

[0020] Furthermore, the single-walled carbon nanotubes are used in carbon nanotube conductive paste.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention uses metal tungsten or metal molybdenum as a metal catalyst, reacts with a promoter under a protective gas atmosphere to synthesize disulfide at high temperature, so that the compound gradually clusters. Subsequently, ditungsten carbide or dimolybdenum carbide is carbonized in a mixed atmosphere of protective gas, hydrogen and carbon source gas, and the size of the catalyst particles is adjusted in combination with hydrogen, thereby achieving matching of the catalyst and the carbon source, ensuring the activity of the catalyst, achieving an increase in carbon yield, and realizing large-scale preparation of single-walled carbon nanotubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0024] Figure 1 The transmission electron microscope characterization of the single-walled carbon nanotubes prepared in Example 1 of the present invention is intended;

[0025] Figure 2 Transmission electron microscope characterization of the single-walled carbon nanotubes prepared in Example 2 of the present invention;

[0026] Figure 3 Transmission electron microscopy characterization of the single-walled carbon nanotubes prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] In the description of the present invention, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inside", "all around" and the like indicating orientation or positional relationship are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] The present invention provides a single-walled carbon nanotube for preparing a carbon nanotube conductive slurry. The preparation method of the single-walled carbon nanotube comprises the following steps:

[0030] (1) The quartz substrate is sequentially cleaned with deionized water, acetone, ethanol and deionized water under the condition of 80-100 kHz and 400-800 W of ultrasonic cleaning for 40-60 min, and then blown dry with a nitrogen gun. The blown-dried quartz substrate is neatly placed in a crucible with the front side facing upward and placed in a muffle furnace. The temperature is raised to 850-950° C. and kept for 8-12 h in an oxygen atmosphere, and then the temperature is lowered to 200-300° C., air is introduced and the substrate is naturally cooled to room temperature to obtain a pretreated substrate;

[0031] (2) Place the catalyst precursor and promoter into the pretreated substrate and place it in the constant temperature zone of the tube furnace at 800-1000 cm 3 A protective gas is introduced at a flow rate of 10 to 20 °C / min, and the temperature is raised to 600 to 800 °C at a rate of 10 to 20 °C / min in the protective gas atmosphere, and the temperature is kept constant for 6 to 10 minutes;

[0032] (3) Preheat the hydrogen to 600-800°C and heat at 400-600 cm 3 Preheated hydrogen is introduced into the tubular furnace at a flow rate of / min, and the temperature is raised to 800-1000°C at a heating rate of 10-20°C / min, and kept at this temperature for 6-10 minutes;

[0033] (4) Preheat the carbon source gas to 600-800°C and heat at 600-800 cm 3 A carbon source gas is introduced into the tubular furnace at a flow rate of / min, and the temperature is kept at 800-1000°C for 20-30min, and the supply of hydrogen and carbon source gas is stopped, the temperature is lowered to 180-220°C, and the supply of protective gas is stopped. Air is introduced and the furnace is cooled to room temperature, and the substrate is taken out to collect the product to obtain single-walled carbon nanotubes with a diameter of 1-3nm.

[0034] Among them, the catalyst precursor is at least one of tungsten oxide, tungsten sulfide, molybdenum oxide, and molybdenum sulfide; the promoter is at least one of sulfur powder, carbon disulfide, mercaptan, and thiophene; the protective gas is at least one of nitrogen, helium, and argon; the carbon source gas is at least one of methane, ethylene, and acetylene.

[0035] Example 1

[0036] The method for preparing single-walled carbon nanotubes of this embodiment comprises the following steps:

[0037] (1) The quartz substrate is sequentially cleaned with deionized water, acetone, ethanol and deionized water under the condition of 80 kHz and 400 W ultrasonic cleaning for 40 min, and then blown dry with a nitrogen gun. The blown-dried quartz substrate is neatly placed in a crucible with the front side facing upward and placed in a muffle furnace. The temperature is raised to 850° C. and kept at this temperature for 8 h in an oxygen atmosphere, then the temperature is lowered to 200° C., air is introduced and the substrate is naturally cooled to room temperature to obtain a pretreated substrate;

[0038] (2) Place tungsten oxide and sulfur powder into the pre-treated substrate and place it in the constant temperature zone of a tube furnace at 800 cm 3 Nitrogen was introduced at a flow rate of 10 °C / min, and the temperature was increased to 600 °C at a rate of 10 °C / min in a nitrogen atmosphere, and the temperature was maintained at this temperature for 6 min;

[0039] (3) Preheat the hydrogen to 600°C and heat at 400 cm 3 Preheated hydrogen was introduced into the tubular furnace at a flow rate of 10 °C / min, and the temperature was raised to 800 °C at a rate of 10 °C / min and kept at this temperature for 6 min;

[0040] (4) Preheat methane to 600°C and heat at 600 cm 3 Methane was introduced into the tubular furnace at a flow rate of / min, and the temperature was kept at 800°C for 20 minutes. The supply of hydrogen and methane was stopped, the temperature was lowered to 180°C, the supply of nitrogen was stopped, air was introduced and cooled to room temperature, the substrate was taken out to collect the product, and single-walled carbon nanotubes with a diameter of 2.05 nm were obtained.

[0041] The single-walled carbon nanotubes prepared in this embodiment have an output rate of 70 g / h. According to calculation, the carbon yield is 12.5%.

[0042] The generated single-walled carbon nanotube powder was subjected to transmission electron microscopy (TEM) to characterize the diameter of the product. The diameter of the product was 2.05nm. The test results are shown in Figure 1 .

[0043] Example 2

[0044] The method for preparing single-walled carbon nanotubes of this embodiment comprises the following steps:

[0045] (1) The quartz substrate is sequentially cleaned with deionized water, acetone, ethanol and deionized water under the condition of 90 kHz and 600 W ultrasonic cleaning for 50 min, and then blown dry with a nitrogen gun. The blown-dried quartz substrate is neatly placed in a crucible with the front side facing upward and placed in a muffle furnace. The temperature is raised to 900° C. and kept for 10 h in an oxygen atmosphere, then cooled to 250° C., air is introduced and naturally cooled to room temperature to obtain a pretreated substrate;

[0046] (2) Place tungsten sulfide and carbon disulfide into the pretreated substrate and place it in the constant temperature zone of a tube furnace at 900 cm 3 Helium was introduced at a flow rate of 15°C / min, and the temperature was raised to 700°C at a rate of 15°C / min in a helium atmosphere, and the temperature was kept constant for 8 min;

[0047] (3) Preheat the hydrogen to 700°C and heat at 500 cm 3Preheated hydrogen was introduced into the tubular furnace at a flow rate of 100 °C / min, and the temperature was raised to 900 °C at a heating rate of 15 °C / min and kept at this temperature for 8 min.

[0048] (4) Preheat ethylene to 700°C and heat at 700 cm 3 Ethylene was introduced into the tubular furnace at a flow rate of 1 / min, and the temperature was kept at 900°C for 25 min. The supply of hydrogen and ethylene was stopped, the temperature was lowered to 200°C, the supply of helium was stopped, air was introduced and the furnace was cooled to room temperature. The substrate was taken out to collect the product, and single-walled carbon nanotubes with a diameter of 1.79 nm were obtained.

[0049] The single-walled carbon nanotubes prepared in this example have an output rate of 72 g / h. According to calculation, the carbon yield is 13.2%.

[0050] The generated single-walled carbon nanotube powder was subjected to transmission electron microscopy (TEM) to characterize the diameter of the product. The diameter of the product was 1.79 nm. The test results are shown in Figure 2 .

[0051] Example 3

[0052] (1) The quartz substrate is sequentially cleaned with deionized water, acetone, ethanol and deionized water at a frequency of 100 kHz and a power of 800 W for 60 minutes by ultrasonic cleaning, and then blown dry with a nitrogen gun. The blown-dried quartz substrate is neatly placed in a crucible with the front side facing upward and placed in a muffle furnace. The temperature is raised to 950° C. and kept for 12 hours in an oxygen atmosphere, then the temperature is lowered to 300° C., air is introduced and the substrate is naturally cooled to room temperature to obtain a pretreated substrate;

[0053] (2) Molybdenum oxide and mercaptan are placed in a pretreated substrate and placed in a constant temperature zone of a tube furnace at 1000 cm 3 Argon was introduced at a flow rate of 1.17 W / min, and the temperature was increased to 800°C at a rate of 20°C / min in an argon atmosphere, and kept at this temperature for 10 min;

[0054] (3) Preheat the hydrogen to 800°C and heat at 600 cm 3 Preheated hydrogen was introduced into the tubular furnace at a flow rate of 1000 °C / min, and the temperature was raised to 1000 °C at a rate of 20 °C / min and kept at this temperature for 10 min.

[0055] (4) Preheat acetylene to 800°C and heat at 800 cm 3 Acetylene was introduced into the tubular furnace at a flow rate of / min, and the temperature was kept at 1000°C for 30 minutes. The supply of hydrogen and acetylene was stopped, the temperature was lowered to 220°C, the supply of argon was stopped, air was introduced and the mixture was cooled to room temperature, the substrate was taken out to collect the product, and single-walled carbon nanotubes with a diameter of 1.60 nm were obtained.

[0056] The single-walled carbon nanotubes prepared in this example have an output rate of 69 g / h. According to calculation, the carbon yield is 12.1%.

[0057] The generated single-walled carbon nanotube powder was subjected to transmission electron microscopy (TEM) to characterize the diameter of the product. The diameter of the product was 1.60nm. The test results are shown in Figure 3 .

[0058] As can be seen from Examples 1 to 3, the method for preparing single-walled carbon nanotubes of the present invention uses metal tungsten or metal molybdenum as a metal catalyst, reacts with a promoter under a protective gas atmosphere to synthesize disulfide at high temperature, so that the compound gradually clusters. Subsequently, ditungsten carbide or dimolybdenum carbide is carbonized in a mixed atmosphere of protective gas, hydrogen and carbon source gas, and the size of the catalyst particles is adjusted in combination with hydrogen, thereby achieving the matching of the catalyst and the carbon source, ensuring the activity of the catalyst, and the carbon yield exceeds 12%. The diameter of the prepared single-walled carbon nanotube is between 1 and 3 nm, realizing the large-scale preparation of single-walled carbon nanotubes.

[0059] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0060] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for preparing single-walled carbon nanotubes, characterized in that: The following steps are involved: (1) annealing the quartz substrate to obtain a pretreated substrate; (2) placing a catalyst precursor and a promoter in a pretreated substrate, placing the substrate in a constant temperature zone of a tube furnace, introducing a protective gas, heating the substrate at a rate of 10 to 20° C. / min to 600 to 800° C. in a protective gas atmosphere, and maintaining the temperature for 6 to 10 minutes; (3) preheating the hydrogen, introducing the preheated hydrogen into the tubular furnace, and simultaneously raising the temperature to 800-1000° C. at a heating rate of 10-20° C. / min, and keeping the temperature for 6-10 min; (4) Preheating the carbon source gas, introducing the carbon source gas into the tubular furnace, maintaining the temperature at 800-1000°C for 20-30 minutes, stopping the supply of hydrogen and carbon source gas, cooling to 180-220°C, stopping the supply of protective gas, introducing air and cooling to room temperature, taking out the substrate to collect the product, and obtaining single-walled carbon nanotubes.

2. The method for preparing single-walled carbon nanotubes according to claim 1, characterized in that: The method for annealing the quartz substrate in step (1) comprises the following steps: The quartz substrate was cleaned with deionized water, acetone, ethanol and deionized water ultrasonically for 40 to 60 minutes in sequence, and then blown dry with a nitrogen gun. The dried quartz substrate was neatly placed in a crucible with the front side facing up and placed in a muffle furnace. The temperature was raised to 850 to 950° C. in an oxygen atmosphere and kept warm for 8 to 12 hours, then cooled to 200 to 300° C., air was introduced and naturally cooled to room temperature to obtain a pretreated substrate.

3. The method for preparing single-walled carbon nanotubes according to claim 2, characterized in that: The ultrasonic cleaning conditions are as follows: frequency 80-100 kHz and power 400-800 W.

4. The method for preparing single-walled carbon nanotubes according to claim 1, characterized in that: The catalyst precursor in step (2) is at least one of tungsten oxide, tungsten sulfide, molybdenum oxide and molybdenum sulfide.

5. The method for preparing single-walled carbon nanotubes according to claim 1, characterized in that: The accelerator in step (2) is at least one of sulfur powder, carbon disulfide, mercaptan and thiophene.

6. The method for preparing single-walled carbon nanotubes according to claim 1, characterized in that: The protective gas in step (2) is at least one of nitrogen, helium and argon, and the flow rate of the protective gas is 800-1000 cm 3 / min.

7. The method for preparing single-walled carbon nanotubes according to claim 1, characterized in that: In step (3), the preheating temperature of hydrogen is 600-800°C, and the flow rate of hydrogen is 400-600 cm 3 / min.

8. The method for preparing single-walled carbon nanotubes according to claim 1, characterized in that: The carbon source gas in step (4) is at least one of methane, ethylene and acetylene, the preheating temperature of the carbon source gas is 600-800°C, and the flow rate of the carbon source gas is 600-800cm / s. 3 / min.

9. The method for preparing single-walled carbon nanotubes according to claim 1, characterized in that: The diameter of the single-walled carbon nanotubes in step (4) is 1 to 3 nm.

10. Use of the single-walled carbon nanotube prepared by the preparation method according to any one of claims 1 to 9 in a carbon nanotube conductive paste.

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