A system for the production of single-walled carbon nanotubes and hydrogen from methane cracking

Abstract

The utility model belongs to carbon nanotube technical field, concretely relates to a system for preparing single wall carbon nanotube and hydrogen with methane cracking. The system includes: arc reaction unit, catalyst injection unit, raw material feeding unit, tail gas separation and purification unit, gas circulation unit, wherein, the arc reaction unit includes electrode anode, electrode cathode, product collection device, cooling device, the raw material feeding unit with the arc reaction unit, tail gas separation and purification unit communicate in proper order, the outlet of catalyst injection unit with the hollow channel of electrode anode in the arc reaction unit communicates. The system can realize the continuous production of single wall carbon nanotube, and greatly improve production efficiency and methane conversion rate, and hydrogen as high value -added product greatly improves the process economy and the comprehensive utilization of resources.

Description

Technical Field

[0001] This invention belongs to the field of carbon nanotube technology, specifically relating to a system for preparing single-walled carbon nanotubes and hydrogen through methane cracking. Background Technology

[0002] Carbon nanotubes, due to their unique structure and excellent mechanical, electrical, and thermal properties, have shown broad application prospects in composite materials, electronic devices, and energy storage. However, the large-scale controllable preparation of high-quality carbon nanotubes remains a key bottleneck restricting their commercial application.

[0003] Currently, the main methods for preparing single-walled carbon nanotubes include arc discharge, laser evaporation, and chemical vapor deposition. Among these, arc discharge is widely used due to its advantages such as simple equipment and good product crystallinity. Traditional arc discharge methods often use graphite electrodes as the carbon source, which suffers from problems such as high electrode consumption and discontinuous process. Although some studies have attempted to replace graphite electrodes with gaseous carbon sources such as methane, problems such as low methane conversion rate and ineffective utilization of tail gas still exist. Furthermore, existing technologies are insufficient in recovering and utilizing the hydrogen and unreacted methane generated during the reaction, leading to resource waste and increased costs.

[0004] Therefore, developing a system capable of continuously preparing high-quality single-walled carbon nanotubes, simultaneously producing hydrogen, and achieving efficient resource recycling is of significant scientific importance and practical value. Utility Model Content

[0005] To address the aforementioned defects or shortcomings, this invention provides a system for preparing single-walled carbon nanotubes and hydrogen through methane cracking, aiming to solve the technical problems of high electrode consumption, difficulty in continuous production, and low raw material utilization in the traditional arc discharge method.

[0006] To achieve the above objectives, this invention provides a system for preparing single-walled carbon nanotubes and hydrogen through methane cracking, the system comprising: The electric arc reaction unit is used to enable methane and catalyst to undergo a cracking reaction through electric arc discharge; A catalyst injection unit is used to load the catalyst into the arc reaction unit in a gas flow manner; A raw material feeding unit is used to introduce raw materials methane and argon into the electric arc reaction unit; The tail gas separation and purification unit is used to separate and purify the tail gas obtained from the pyrolysis reaction; A gas circulation unit is used to circulate the separated methane and argon gas into the arc reaction unit; The electric arc reaction unit includes an electrode anode, an electrode cathode, a product collection device, and a cooling device; the electrode anode and the electrode cathode are coaxially arranged with a gap between them; the electrode anode is a graphite electrode with a hollow channel; a cavity is formed in the electrode cathode at the axial end opposite to the hollow channel of the electrode anode; The raw material feeding unit is sequentially connected to the electric arc reaction unit and the tail gas separation and purification unit; the outlet of the catalyst injection unit is connected to the hollow channel of the electrode anode in the electric arc reaction unit.

[0007] In this embodiment of the invention, both the anode and the cathode are cylindrical; and / or the gap between the anode and the cathode is 2-6 mm.

[0008] In this embodiment of the invention, the inner diameter of the electrode anode is 3-7 mm; the outer diameter is 12-18 mm.

[0009] In this embodiment of the invention, the cathode electrode is a graphite electrode with a concave cavity.

[0010] In this embodiment of the invention, the concave cavity is a cylindrical cavity.

[0011] In this embodiment of the invention, the ratio of the depth of the cavity to the length of the cathode is 1:15-20; the ratio of the diameter of the cavity to the diameter of the cathode is 0.5-0.8:1.

[0012] In this embodiment of the invention, the arc reaction unit is further provided with an external power supply, which is connected to the electrode anode and the electrode cathode respectively.

[0013] In this embodiment of the invention, the product collection device is a wire mesh.

[0014] In this embodiment of the invention, the cooling device is a cooling jacket.

[0015] In this embodiment of the invention, a heat exchange medium is circulated in the cooling jacket, and the heat exchange medium is used to exchange heat with the products obtained from the pyrolysis reaction.

[0016] In this embodiment of the invention, the exhaust gas separation and purification unit is provided with a condenser, a pressure swing adsorption device, and a membrane separation device in sequence.

[0017] Through the above technical solution, the system for preparing single-walled carbon nanotubes and hydrogen by methane cracking provided in this embodiment of the present invention has the following beneficial effects: When using the aforementioned system for preparing single-walled carbon nanotubes and hydrogen through methane cracking, the inclusion of an arc reaction unit, catalyst injection unit, raw material feeding unit, tail gas separation and purification unit, and gas circulation unit enables continuous production of single-walled carbon nanotubes, significantly improving production efficiency and methane conversion rate. Simultaneously, hydrogen, as a high-value-added product, greatly enhances process economics and comprehensive resource utilization. The tail gas separation and purification unit and gas circulation unit enable efficient utilization of unreacted methane and argon, significantly reducing raw material consumption and costs. Furthermore, the system provided by this invention achieves near-zero emissions throughout the entire process, meeting green manufacturing requirements. Moreover, due to the efficient utilization of raw materials and energy, it possesses excellent economic benefits and commercial prospects.

[0018] Other features and advantages of this invention will be described in detail in the following detailed description section. Attached Figure Description

[0019] The accompanying drawings are provided to illustrate the present invention and form part of the specification. They are used together with the following detailed description to explain the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the system for preparing single-walled carbon nanotubes and hydrogen by methane cracking according to an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures 1. Arc reaction unit; 2. Electrode anode; 3. Electrode cathode; 4. Catalyst injection unit; 5. Raw material feeding unit; 6. Exhaust gas outlet; 7. Product collection device; 8. Tail gas separation and purification unit; 9. Gas circulation unit; 10. External power supply; 11. Heat exchange medium; 12. Hydrogen. Detailed Implementation

[0021] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.

[0022] The system for preparing single-walled carbon nanotubes and hydrogen by methane cracking according to the present invention is described below with reference to the accompanying drawings.

[0023] like Figure 1As shown, this utility model provides a system for preparing single-walled carbon nanotubes and hydrogen by methane cracking. The system includes: The electric arc reaction unit is used to enable methane and catalyst to undergo a cracking reaction through electric arc discharge; A catalyst injection unit is used to load the catalyst into the arc reaction unit in a gas flow manner; A raw material feeding unit is used to introduce raw materials methane and argon into the electric arc reaction unit; The tail gas separation and purification unit is used to separate and purify the tail gas obtained from the pyrolysis reaction; A gas circulation unit is used to circulate the separated methane and argon gas into the arc reaction unit; The electric arc reaction unit includes an electrode anode, an electrode cathode, a product collection device, and a cooling device; the electrode anode and the electrode cathode are coaxially arranged with a gap between them; the electrode anode is a graphite electrode with a hollow channel; a cavity is formed in the electrode cathode at the axial end opposite to the hollow channel of the electrode anode; The raw material feeding unit is sequentially connected to the electric arc reaction unit and the tail gas separation and purification unit; the outlet of the catalyst injection unit is connected to the hollow channel of the electrode anode in the electric arc reaction unit.

[0024] This invention employs a specific electric arc reaction unit combined with a catalyst injection unit, achieving a continuous preparation process and increasing production efficiency by 3-5 times compared to traditional methods.

[0025] In this embodiment of the invention, the volume ratio of methane to argon in the raw material feeding unit is 1:3-10.

[0026] In this invention, unless otherwise specified, the "gap" between the anode 2 and the cathode 3 represents the shortest distance between the two electrodes.

[0027] In this invention, the arc region formed by the gap between the electrode anode 2 and the electrode cathode 3 serves as the main reaction region for the arc discharge reaction.

[0028] In this invention, the coaxial arrangement of the electrode anode 2 and the electrode cathode 3 means that the electrode anode 2 and the electrode 3 are arranged opposite each other along the axial direction (i.e., the length direction) of the electrode, and the center of the electrode anode 2 and the center of the electrode cathode 3 are located on the same axis.

[0029] In this invention, the axial end of the cathode 3 that is opposite to the hollow channel of the anode 2 refers to the end of the cathode 3 that is closest to the anode 2 in the axial direction.

[0030] In this embodiment of the invention, the positions of the anode 2 and cathode 3 can be controlled by an external motor to achieve continuous operation.

[0031] In this invention, the cavity in the cathode 3 extends along the electrode axis.

[0032] In this embodiment of the invention, both the anode 2 and the cathode 3 are cylindrical.

[0033] In this embodiment of the invention, the gap between the anode 2 and the cathode 3 is 2-6 mm. Under this condition, a continuous and stable electric arc can be maintained, enabling the continuous fabrication of carbon nanotubes.

[0034] In this embodiment of the invention, the inner diameter of the electrode anode 2 is 3-7 mm; the outer diameter is 12-18 mm.

[0035] In this embodiment of the invention, the length of the electrode anode 2 is 60-80 mm.

[0036] In this embodiment of the invention, the cathode 3 is a graphite electrode with a concave cavity.

[0037] In this invention, the central axis of the concave cavity coincides with the central axis of the cathode electrode 3.

[0038] In this embodiment of the invention, the diameter of the cathode 3 is 12-20 mm, and the length of the cathode 3 is 60-80 mm.

[0039] In this embodiment of the invention, the concave cavity is a cylindrical cavity.

[0040] More preferably, the ratio of the depth of the cavity to the length of the electrode cathode is 1:15-20; the ratio of the diameter of the cavity to the diameter of the electrode cathode 3 is 0.5-0.8:1. Under these preferred conditions, an appropriate amount of catalyst can be received for the cracking reaction, thereby improving the reaction efficiency.

[0041] More preferably, the diameter of the cavity is greater than or equal to the inner diameter of the electrode anode.

[0042] In this embodiment of the invention, the arc reaction unit is further provided with an external power supply 10, which is connected to the electrode anode 2 and the electrode cathode 3 respectively. The external power supply serves as an arc power source.

[0043] In this embodiment of the invention, the product collection device is a wire mesh.

[0044] In this embodiment of the invention, the product collection device is located outside the area formed by the electrode anode and the electrode cathode.

[0045] In this embodiment of the invention, the cooling device is a cooling jacket.

[0046] In this embodiment of the invention, a heat exchange medium 11 is circulated in the cooling jacket, and the heat exchange medium is used to exchange heat with the products obtained from the pyrolysis reaction.

[0047] In some embodiments, the heat exchange medium is circulating cooling water, which is used to cool the single product obtained from the pyrolysis reaction.

[0048] In this embodiment of the invention, the arc reaction unit 1 is made of stainless steel.

[0049] In this embodiment of the invention, the arc reaction unit 1 adopts a hollow tubular structure.

[0050] In this embodiment of the invention, the diameter of the arc reaction unit 1 is 200-600mm and the height is 320-400mm.

[0051] In this embodiment of the present invention, the arc reaction unit 1 is further provided with a first inlet, a second inlet, and a tail gas outlet 6. The tail gas outlet 6 is connected to the inlet of the tail gas separation and purification unit 8; the first inlet is connected to the outlet of the raw material feeding unit 5; and the second inlet is connected to the outlet of the catalyst injection unit 4.

[0052] In this embodiment of the invention, the arc reaction unit 1 is further provided with an observation window for observing the reaction in the arc reaction unit 1.

[0053] In this embodiment of the invention, the first inlet is located on the side wall of the arc reaction unit 1, and the second inlet is located on the top of the arc reaction unit 1.

[0054] More preferably, the center of the gap between the electrode anode 2 and the electrode cathode 3 is on the same straight line as the center of the first inlet.

[0055] In this embodiment of the present invention, the tail gas separation and purification unit 8 is provided with a condenser, a pressure swing adsorption device and a membrane separation device in sequence.

[0056] In this invention, the condenser is used for cryogenic separation to remove carbon particles, a byproduct.

[0057] In this invention, the pressure swing adsorption device is used to concentrate hydrogen gas.

[0058] In this invention, the membrane separation device is used for the purification of hydrogen.

[0059] In this invention, the tail gas separation and purification unit 8 can separate hydrogen from the tail gas and recover unreacted methane and argon.

[0060] In this embodiment of the present invention, the tail gas separation and purification unit 8 is further provided with a first outlet and a second outlet. The first outlet of the tail gas separation and purification unit is connected to the first inlet of the electric arc reaction unit 1. The second outlet of the tail gas separation and purification unit is used to collect purified hydrogen gas 12.

[0061] In this invention, the catalyst is injected into the cavity in the cathode 3 through the hollow channel of the anode 2; that is, the hollow channel of the anode 2 is used to transport the catalyst, and the cavity in the cathode 3 is used to receive the catalyst.

[0062] In this embodiment of the invention, the catalyst injection unit includes a catalyst storage tank and a catalyst injection rate controller, which can uniformly inject nanoscale catalyst into the cavity of the arc reaction unit 1.

[0063] In this embodiment of the invention, the catalyst in the catalyst injection unit contains a transition metal element and a rare earth metal element in a mass ratio of 10-50:1; the transition metal element is at least one of iron, cobalt, and nickel; and the rare earth metal element is selected from at least one of yttrium, cerium, and lanthanum.

[0064] In this embodiment of the invention, the catalyst injection rate is controlled by the catalyst injection rate controller, and the injection rate is preferably 0.1-0.5 g / min.

[0065] In this embodiment of the invention, the gas circulation unit 9 includes a compressor and a flow controller, which can circulate the separated methane and argon to the arc reaction unit 1.

[0066] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0067] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0068] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0069] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A system for preparing single-walled carbon nanotubes and hydrogen by methane cracking, characterized in that, The system includes: An electric arc reaction unit (1) is used to enable methane and a catalyst to undergo a cracking reaction through electric arc discharge; The catalyst injection unit (4) is used to load the catalyst into the arc reaction unit (1) in a gas flow manner; The raw material feeding unit (5) is used to introduce raw materials methane and argon into the electric arc reaction unit (1); The tail gas separation and purification unit (8) is used to separate and purify the tail gas obtained from the pyrolysis reaction; Gas circulation unit (9) is used to circulate the separated methane and argon to the electric arc reaction unit (1); The electric arc reaction unit (1) includes an electrode anode (2), an electrode cathode (3), a product collection device (7), and a cooling device; the electrode anode (2) and the electrode cathode (3) are coaxially arranged and have a gap; the electrode anode (2) is a graphite electrode with a hollow channel; a cavity is provided in the axial end of the electrode cathode (3) opposite to the hollow channel of the electrode anode (2); The raw material feeding unit (5) is connected in sequence to the electric arc reaction unit (1) and the tail gas separation and purification unit (8); the outlet of the catalyst injection unit (4) is connected to the hollow channel of the electrode anode (2) in the electric arc reaction unit (1).

2. The system according to claim 1, characterized in that, Both the anode (2) and the cathode (3) are cylindrical.

3. The system according to claim 1 or 2, characterized in that, The inner diameter of the electrode anode (2) is 3-7 mm; the outer diameter is 12-18 mm.

4. The system according to claim 1 or 2, characterized in that, The cathode (3) is a graphite electrode with a concave cavity.

5. The system according to claim 1 or 2, characterized in that, The cavity is a cylindrical cavity; And / or, the ratio of the depth of the cavity to the length of the cathode (3) is 1:15-20; the ratio of the diameter of the cavity to the diameter of the cathode (3) is 0.5-0.8:

1.

6. The system according to claim 1 or 2, characterized in that, The arc reaction unit (1) is also provided with an external power supply (10), which is connected to the electrode anode (2) and the electrode cathode (3) respectively.

7. The system according to claim 1 or 2, characterized in that, The product collection device is a wire mesh.

8. The system according to claim 1 or 2, characterized in that, The cooling device is a cooling jacket.

9. The system according to claim 8, characterized in that, The cooling jacket is filled with a heat exchange medium (11), which is used to exchange heat with the products obtained from the pyrolysis reaction.

10. The system according to claim 1 or 2, characterized in that, The tail gas separation and purification unit (8) is provided with a condenser, a pressure swing adsorption device and a membrane separation device in sequence.

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