Production device and production method of single-walled carbon nanotube

Abstract

The invention discloses a production device and a production method of a single-walled carbon nanotube. The device comprises a water gas preparation chamber, a quenching growth chamber, a cyclone separation chamber and a collection chamber which are hermetically connected, the water gas preparation chamber comprises at least one independent cavity; the rear end of the chamber is connected with the quenching growth chamber, and the rear end of the quenching growth chamber is connected with the collecting chamber through the cyclone separator; wherein a movable plasma gun is arranged in each cavity, a material containing box is arranged at the bottom of each cavity, and materials in the material containing boxes are gasified through high-temperature heat flow generated by the plasma guns; the plasma gun is further connected with gas modulation equipment, and gasification products are adjusted by adjusting gas composition output by the gas modulation equipment. Continuous operation of the electric arc can be achieved by supplementing raw materials to the bottom of the cavity, the defect that an electric arc gun is short in service life is overcome, the automation degree is high, and the conversion rate is high.

Description

Technical Field

[0001] This invention relates to the field of electric arc thermal plasma technology, and more particularly to a production apparatus and method for single-walled carbon nanotubes. Background Art

[0002] A plasma torch refers to the phenomenon where applying a certain voltage between two electrodes ionizes a gas and maintains its conductivity. It is the most intense self-sustaining discharge in gas discharge, emitting a bright glow and generating high temperatures (2000℃–10000℃). An electric arc is a common type of thermal plasma that can evaporate high-melting-point substances such as graphite and tungsten. Arc discharge can also be used for reactions such as the halogenation of metal oxides and the thermal decomposition of low-boiling-point hydrocarbons. Therefore, arc discharge has extremely high engineering application value.

[0003] Arc discharge is a traditional method for preparing highly crystalline carbon nanomaterials. This method utilizes an arc device or process that grows carbon nanomaterials by ablating graphite electrodes. Forcing the graphite electrode to evaporate and ablate requires extremely high temperatures (melting point 3850±50℃, boiling point 4250℃), thus increasing the overall energy consumption of the arc system. The ablated graphite anode is easily depleted due to its size. At this point, it is necessary to wait for the arc furnace to completely cool down, then vent it, open the furnace, replace the graphite anode, and repeat the vacuuming process, introducing ionized gas for preheating and repeating the arc reaction. This significantly reduces the preparation efficiency. Furthermore, the arc gun cannot operate continuously and has a short lifespan, making it unsuitable for industrial-scale mass production. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a production apparatus and method for single-walled carbon nanotubes, which can improve preparation efficiency.

[0005] In a first aspect, the present invention provides a production apparatus for single-walled carbon nanotubes, comprising: a water gas preparation chamber, a quenching growth chamber, a cyclone separation chamber, and a collection chamber connected in sequence and sealed together; the water gas preparation chamber includes at least two independent chambers, which are connected to each other to form a double chamber; the rear end of the double chamber is connected to the quenching growth chamber, and the rear end of the quenching growth chamber is connected to the collection chamber via a cyclone separator;

[0006] The chamber is equipped with a movable plasma gun, which is connected to the positive and negative terminals of the plasma generator power supply, respectively. The bottom of each chamber is equipped with a material container. The chamber is also connected to a modulated gas generator.

[0007] In one alternative embodiment, the modulated gas device is connected to the plasma gun to provide a high-temperature gas flow to the water gas preparation chamber.

[0008] In one alternative embodiment, the walls of the water gas preparation chamber are composed of a water-cooled stainless steel outer wall and a high-temperature refractory brick inner wall.

[0009] In one alternative embodiment, an electric heating device is provided in the inner wall of the high-temperature refractory brick, the electric heating device being used to assist heating to increase the internal temperature of the water gas preparation chamber.

[0010] In one optional embodiment, cooling circulating water flows through the water-cooled stainless steel outer wall, and cooling circulating water also flows through the outer wall of the plasma gun, sharing a cooling tower with the water-cooled stainless steel outer wall.

[0011] In one alternative embodiment, the interior of the quenching growth chamber is provided with a scraper for removing deposited powder.

[0012] In one optional embodiment, the quenching growth chamber includes a horizontal tubular furnace body and an outer wall, and the horizontal tubular furnace body and the outer wall of the quenching growth chamber are protected by heat insulation material.

[0013] A second aspect of the present invention provides a method for producing single-walled carbon nanotubes, comprising:

[0014] The material is placed in a material container, and the pressure in the water gas preparation chamber is drawn to a preset pressure value using a vacuum pump. A high-temperature gas flow is introduced into the water gas preparation chamber using a gas modulation device until the pressure in the water gas preparation chamber reaches atmospheric pressure. The plasma gun is then turned on to generate high temperature to partially melt the material.

[0015] Modulated gas is introduced into the water-cooled electric arc device using a steam generator and an oxygen compression device. The power supply of the plasma generator is turned on to ignite the electric arc heat flow and evaporate the material in the material container. The indoor temperature of the water gas preparation chamber is controlled at 400℃-1800℃ to produce water gas containing nano-iron particles and sulfide vapor.

[0016] The temperature of the quenching growth chamber is controlled at 700℃-1500℃. The water gas enters the quenching growth chamber and the water gas is subjected to cold treatment of single-wall carbon nanotubes and tail gas in the quenching growth chamber for 0.02min-120min.

[0017] The single-walled carbon nanotubes generated in the quenching growth chamber and the exhaust gas are separated by a cyclone separator, and the single-walled carbon nanotube powder enters the collection chamber.

[0018] In one alternative embodiment, the method further includes returning the tail gas, after passing component analysis, to the water gas preparation chamber.

[0019] In one optional embodiment, the water gas is subjected to cold treatment with single-walled carbon nanotubes and tail gas in a quenching growth chamber for a time of 1 to 60 seconds.

[0020] In one alternative embodiment, the material is coal and iron, with a coal-to-iron mass ratio of 90wt%-99wt%:1wt%-10wt%.

[0021] In one alternative embodiment, the coal composition is:

[0022] C: 60wt%–98wt%;

[0023] H: 3wt% - 28wt%;

[0024] O: 4wt% - 26wt%;

[0025] N: 0.5wt%–1wt%;

[0026] S: 0.1wt% - 0.5wt%.

[0027] In one alternative embodiment, the size of the nano-iron particles is 1 nm to 40 nm.

[0028] In one alternative embodiment, the mass ratio of nano-iron particles, sulfide vapor, and water gas is 1.00wt%–10.00wt%: 0.02wt%–0.10wt%: 89.90wt%–98.98wt%.

[0029] In one optional embodiment, the water gas is composed of carbon monoxide and hydrogen, with a volume ratio of carbon monoxide to hydrogen of 34 vol%–95 vol%: 5 vol%–66 vol%.

[0030] This invention enables continuous operation by replenishing raw materials to the bottom of the chamber, avoiding the drawbacks of short service life associated with using an arc gun, and also features a high degree of automation and high conversion rate.

[0031] The exhaust gas generated by this invention can be returned to the water gas preparation room for reuse after component analysis, resulting in high raw material utilization. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a single-walled carbon nanotube production apparatus according to an embodiment of the present invention.

[0033] Figure 2 This is a schematic diagram of the water gas preparation chamber in an embodiment of the present invention.

[0034] Figure 3 This is a schematic diagram of the structure of the wall of the water gas preparation chamber in an embodiment of the present invention.

[0035] Figure 4 This is a schematic diagram of the quenching growth chamber in an embodiment of the present invention.

[0036] Figure 5 This is a schematic flowchart of a method for producing single-walled carbon nanotubes according to an embodiment of the present invention.

[0037] Figure 6 This is a scan image of the single-walled carbon nanotubes prepared in the embodiments of the present invention.

[0038] Figure 7 This is the Raman spectrum of the single-walled carbon nanotubes prepared in the embodiments of the present invention.

[0039] 1. Water gas preparation chamber; 2. Quenching and growth chamber; 3. Cyclone separation chamber; 4. Collection chamber; 5. Cavity; 6. Plasma gun; 7. Material container; 8. Gas modulation equipment; 9. Plasma generator power supply; 21. Horizontal tubular furnace body; 22. Outer wall; 23. Water-cooled stainless steel outer wall; 24. High-temperature refractory brick inner wall; 25. Electric heating device; 26. Thermal insulation material; 27. Scraper. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0042] Please see Figure 1 and Figure 2As shown, this invention provides a production apparatus for single-walled carbon nanotubes, comprising: a water-gas preparation chamber 1, a quenching growth chamber 2, a cyclone separator 3, and a collection chamber 4, all sealed together by pipes. The water-gas preparation chamber 1 includes at least one independent cavity 5. The rear end of the cavity 5 is connected to the quenching growth chamber 2 via a pipe, and the rear end of the quenching growth chamber 2 is connected to the collection chamber 4 via a cyclone separator 3. The cyclone separator 3 is a device for separating gas-solid or liquid-solid systems, capable of separating single-walled carbon nanotubes and exhaust gas.

[0043] like Figure 2 As shown, a movable plasma gun 6 is installed in chamber 5; specifically, the plasma gun 6 can be moved by a stepper. A plasma generator power supply 9 is connected to the two electrodes of the plasma gun 6. A material container 7 is located at the bottom of chamber 5, and the material container 7 holds the material.

[0044] like Figure 1 As shown, the chamber 5 is also connected to a gas modulation device 8, which is used to deliver hot gas flow into the chamber.

[0045] Furthermore, during the production of single-walled carbon nanotubes, materials can be continuously added to the material container 7 through the feed inlet. This invention enables continuous operation by replenishing materials through the material container 7, solving the problem of short lifespan when using an arc gun and improving preparation efficiency.

[0046] In this invention, the output end of the gas modulation device 8 is connected to the plasma gun 6 to modulate the hot air flow into the chamber 5 of the water gas preparation chamber 1, which can realize automated control and improve the automation level of the single-walled carbon nanotube production device.

[0047] See Figure 1 As shown, the gas modulation device 8 can also be connected to a metering pump, and the output gas can be regulated by controlling the metering pump.

[0048] Furthermore, the walls of the water gas preparation chamber 1 are composed of a water-cooled stainless steel outer wall 23 and a high-temperature refractory brick inner wall 24. An electric heating device 25 is installed in the high-temperature refractory brick inner wall 24. This device is used for auxiliary heating to increase the internal temperature of the water gas preparation chamber 1. The temperature of the electric heating device 25 can be controlled by an electrical control device, and the device can be a heating wire. The water-cooled stainless steel outer wall 23 is made of stainless steel and has a circulating cooling water jacket space inside. The outer wall of the plasma gun 6 also has a circulating cooling water jacket space. The plasma gun 6 and the water-cooled stainless steel outer wall 23 can share a single cooling tower, with a cooling water operating temperature of 0℃-80℃, eliminating the need for separate chillers. Therefore, the present invention has a simple structure and is easy to control.

[0049] To facilitate the cleaning of impurities within the quenching growth chamber 2, a scraper 27 for removing deposited powder is provided inside the quenching growth chamber 2. The scraper 27 is capable of rotating along the inner wall of the quenching growth chamber 2, specifically driven by a motor to move along an axis. The quenching growth chamber 2 includes a horizontal tubular furnace body 21 and an outer wall 22, which are protected by a heat-insulating material 26 (such as glass wool, polystyrene foam, or foam plastic laminate composite material).

[0050] This invention enables continuous operation by replenishing materials to the bottom of the chamber, solving the problem of short service life of arc guns. It can also automatically control plasma guns, plasma generators, gas modulation equipment and vacuum pumps, achieving a high degree of automation.

[0051] Please see Figure 3 The present invention also provides a method for producing single-walled carbon nanotubes based on the above-described single-walled carbon nanotube production apparatus, comprising the following steps.

[0052] Step 100: Place the material into the material container and use a vacuum pump to draw the pressure in the water gas preparation chamber to the preset pressure value; use a gas modulation device to introduce modulation gas into the water gas preparation chamber until the pressure in the water gas preparation chamber reaches atmospheric pressure, and turn on the plasma gun to input a high-temperature gas flow to partially melt the material.

[0053] The preset pressure value is less than 30 Pa. When adding materials, the material container can be filled to the brim, and then the pressure in the water gas preparation chamber can be reduced to less than 30 Pa, such as 25 Pa, 29 Pa, or 20 Pa. Then, the pressure is introduced to atmospheric pressure through a modulator, and then a plasma hot gas flow is introduced to partially melt the materials.

[0054] The materials are coal and iron, with a coal to iron mass ratio of 90wt%-99wt%:1wt%-10wt%.

[0055] In some embodiments, the coal composition is: C: 60wt%–98wt%, H: 3wt%–28wt%, O: 4wt%–26wt%, N: 0.5wt%–1wt%, S: 0.1wt%–0.5wt%.

[0056] Step 200: Using a gas modulation device, modulating gas is introduced into the plasma gun, the power supply of the plasma generator is turned on to generate a hot gas flow and evaporate the material in the material container, and the indoor temperature of the water gas preparation chamber is controlled at 400℃-1800℃ to prepare water gas containing nano-iron particles and sulfide vapor.

[0057] Then, modulation gas is continuously introduced to initiate a hot gas flow and evaporate the material. The mass ratio of the prepared nano-iron particles, sulfide vapor, and water gas is 1.00wt%–10.00wt%: 0.02wt%–0.10wt%: 89.90wt%–98.98wt%. The nano-iron particles have a size of 1nm–40nm.

[0058] The water gas consists of carbon monoxide and hydrogen, with a volume ratio of 34 vol%–95 vol%: 5 vol%–66 vol%.

[0059] Step 300: Control the indoor temperature of the quenching growth chamber to 700℃-1500℃. The water gas enters the quenching growth chamber and the water gas is subjected to cold treatment of single-wall carbon nanotubes and tail gas in the quenching growth chamber for 0.02min-120min.

[0060] In some embodiments, the water gas is subjected to cold treatment of single-walled carbon nanotubes and tail gas in a quenching growth chamber for a time of 1 to 60 seconds. In other embodiments, the cold treatment time is 60 min to 100 min, or 0.02 min to 2 min, or 1 s, 60 s, 5 min, 80 min, etc.

[0061] In some embodiments, the indoor temperature of the quenching growth chamber can also be controlled to be 850℃-1100℃.

[0062] Step 400: The single-walled carbon nanotubes and exhaust gas generated in the quenching growth chamber are separated by a cyclone separator, and the single-walled carbon nanotube powder enters the collection chamber.

[0063] Furthermore, the method further includes returning the qualified tail gas from component analysis to the water gas preparation chamber, thereby improving the raw material utilization rate. In some embodiments, the direct yield of single-walled carbon nanotubes is close to 60%, the raw material recycling yield is close to 30%, and the overall yield is close to 90%. The scanning image of the prepared single-walled carbon nanotubes is shown below. Figure 4 As shown, single-walled carbon nanotubes exist in the form of bundles, with some spherical catalyst particles remaining within the bundles; the Raman spectra of single-walled carbon nanotubes are as follows. Figure 5 As shown, the GD (dynamic shear modulus ratio) of the single-walled carbon nanotube product is 103, and the RBM (Radial Breathing Mode) peak intensity is higher than that of competing products produced by existing technologies, such as the single-walled carbon nanotubes produced by foreign competing companies OCSiAl (Nanotechnology Company).

[0064] In summary, this invention enables continuous operation by replenishing raw materials to the material container at the bottom of the dual chambers, avoiding the drawbacks of short service life associated with using an electric arc gun. It features high automation, high conversion rate, and the exhaust gas can be returned to the water gas preparation chamber for reuse after component analysis, resulting in high raw material utilization.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A production apparatus for single-walled carbon nanotubes, characterized in that, It includes: a water gas preparation chamber, a quenching growth chamber, a cyclone separation chamber, and a collection chamber, all sealed together; the water gas preparation chamber includes at least one independent chamber; the rear end of the chamber is connected to the quenching growth chamber, and the rear end of the quenching growth chamber is connected to the collection chamber via a cyclone separator; Each chamber is equipped with a movable plasma gun, and the bottom of each chamber is equipped with a material container. The material in the material container is vaporized by the high-temperature heat flow generated by the plasma gun. The plasma gun is also connected to a gas modulation device, and the vaporization products are adjusted by adjusting the gas composition output by the gas modulation device.

2. The apparatus for producing single-walled carbon nanotubes according to claim 1, characterized in that, The transfer arc plasma gun below the chamber directly vaporizes the material in the material container using a high-temperature gas flow.

3. The apparatus for producing single-walled carbon nanotubes according to claim 1 or 2, characterized in that, The walls of the water gas preparation chamber are composed of a water-cooled stainless steel outer wall and a high-temperature refractory brick inner wall.

4. The apparatus for producing single-walled carbon nanotubes according to claim 3, characterized in that, An electric heating device is provided in the inner wall of the high-temperature refractory brick. The electric heating device is used to assist heating to increase the internal temperature of the water gas preparation chamber.

5. The apparatus for producing single-walled carbon nanotubes according to claim 3, characterized in that, Cooling circulating water flows through the water-cooled stainless steel outer wall, and cooling circulating water also flows through the outer wall of the plasma gun. Both the water-cooled stainless steel outer wall and the plasma gun share a cooling tower.

6. The apparatus for producing single-walled carbon nanotubes according to claim 1, characterized in that, The interior of the quenching growth chamber is equipped with a scraper for removing deposited powder.

7. The apparatus for producing single-walled carbon nanotubes according to claim 6, characterized in that, The quenching growth chamber includes a horizontal tubular furnace body and an outer wall, and the horizontal tubular furnace body and the outer wall of the quenching growth chamber are protected by heat insulation material.

8. A method for producing single-walled carbon nanotubes based on the production apparatus of any one of claims 1 to 7, characterized in that, include: The material is placed in a material container, and the pressure in the water gas preparation chamber is drawn to the preset pressure value using a vacuum pump. Modulation gas is introduced into the water gas preparation chamber using a gas modulation device until the pressure in the water gas preparation chamber reaches atmospheric pressure. The plasma gun is turned on to input a high-temperature gas flow to partially melt and gasify the material. The indoor temperature of the water gas preparation chamber is controlled at 400℃-1800℃ to prepare gasification products containing nano-iron particles and sulfide vapor. The temperature of the quenching growth chamber is controlled at 700℃-1500℃. The water gas enters the quenching growth chamber and the water gas is subjected to cold treatment of single-wall carbon nanotubes and tail gas in the quenching growth chamber for 0.02min-120min. The single-walled carbon nanotubes generated in the quenching growth chamber and the exhaust gas are separated by a cyclone separator, and the single-walled carbon nanotube powder enters the collection chamber.

9. The method for producing single-walled carbon nanotubes according to claim 8, characterized in that, The method further includes returning the tail gas, after passing component analysis, to the water gas preparation chamber.

10. The method for producing single-walled carbon nanotubes according to claim 8, characterized in that, The water gas is subjected to cold treatment with single-walled carbon nanotubes and tail gas in a quenching growth chamber for a time of 1 to 60 seconds.

11. The method for producing single-walled carbon nanotubes according to claim 8, characterized in that, The materials are coal and iron, with a coal to iron mass ratio of 90wt%-99wt%:1wt%-10wt%.

12. The method for producing single-walled carbon nanotubes according to claim 11, characterized in that, The composition of the coal is: C: 60wt%–98wt%; H: 3wt% - 28wt%; O: 4wt% - 26wt%; N: 0.5wt%–1wt%; S: 0.1wt% - 0.5wt%.

13. The method for producing single-walled carbon nanotubes according to claim 11, characterized in that, The size of the nano-iron particles is 1nm-40nm.

14. The method for producing single-walled carbon nanotubes according to claim 8, characterized in that, The mass ratio of nano-iron particles, sulfide vapor, and water gas is 1.00wt%–10.00wt%: 0.02wt%–0.10wt%: 89.90wt%–98.98wt%.

15. The method for producing single-walled carbon nanotubes according to claim 8, characterized in that, The water gas is composed of carbon monoxide and hydrogen, with a volume ratio of 34 vol%–95 vol%: 5 vol%–66 vol%.

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