Device and method for preparing carbon nanotube aerogel through low-pressure combustion of gaseous hydrocarbon

Abstract

The invention belongs to the technical field of carbon nano tube aerogel preparation, and discloses a device and method for preparing carbon nano tube aerogel through low-pressure combustion of gaseous hydrocarbon, the device comprises a low-pressure combustor, a combustion platform, a catalyst feeding device, a gas supply device, a monitoring device and an aerogel forming device, the combustion platform is located in the combustion reaction cavity and moves up and down through a brushless motor. The catalyst feeding device gasifies a catalyst through a heating sleeve and conveys the catalyst to the combustion platform through argon. The gas supply device provides gaseous hydrocarbon fuel, oxygen and carrier gas; the monitoring device monitors pressure and temperature in real time; the aerogel forming device realizes in-situ self-assembly of the carbon nanotubes through vacuum suction. According to the method, a low-pressure combustion method is adopted, continuous preparation of the carbon nanotube aerogel is achieved, and the method has the advantages of being simple and convenient in process, low in energy consumption and high in structural integration degree and is suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon nanotube aerogel preparation, and particularly relates to a device and method for preparing carbon nanotube aerogel by low-pressure combustion of gaseous hydrocarbons. Background Art

[0002] Carbon nanotubes (CNTs), with their excellent electrical conductivity, large surface area, and exceptional mechanical properties, hold a significant position in energy storage devices, electrocatalysis, and electrothermal materials. Assembling CNTs into aerogels with three-dimensional network structures can further enhance their structural stability and functional integration, showing promising applications in flexible electronics, supercapacitors, and thermal management materials.

[0003] Existing methods for preparing carbon nanotube aerogels primarily rely on techniques such as solution assembly, template replication, or freeze-drying. However, these methods are generally complex, energy-intensive, and difficult to scale up for continuous production. Combustion, a heat-sustaining, efficient, and simple method, utilizes gaseous hydrocarbons (such as methane, ethane, and ethylene) as a carbon source. Using transition metal catalysts, it enables rapid growth of carbon nanotubes, which can then self-assemble into carbon nanotube-based aerogels under low pressure. Compared to traditional methods, combustion significantly reduces energy consumption and offers good industrial applicability. However, there are currently no reports on the preparation of carbon nanotube-based aerogels via low-pressure combustion.

[0004] Therefore, developing a device and method for continuously producing carbon nanotube aerogels with simple process, low energy consumption, has become a technical problem to be solved urgently in this field. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a device and method for preparing carbon nanotube aerogels by low-pressure combustion of gaseous hydrocarbons. The device has a high degree of structural integration and simple method steps, can achieve in-situ continuous growth of carbon nanotube aerogels, has low energy consumption, is environmentally friendly, and is suitable for industrial production.

[0006] In order to achieve the above-mentioned purpose of the invention, the technical solutions adopted are as follows: A device for preparing carbon nanotube aerogel by low-pressure combustion of gaseous hydrocarbons, comprising: A low-pressure burner, the interior of which is a combustion reaction chamber; The combustion platform is arranged inside the combustion reaction chamber, and its lower end is connected to a brushless motor to achieve up and down reciprocating movement, which is used to generate a stable premixed flame; A catalyst feeding device comprises a catalyst tank installed in a wrapped heating jacket, wherein an outlet pipe of the catalyst tank is connected to the combustion platform; A gas supply device, comprising a gaseous hydrocarbon cylinder, an oxygen cylinder and an argon cylinder, wherein the gas outlet pipes of the gaseous hydrocarbon cylinder and the oxygen cylinder are connected to the combustion platform for providing fuel and oxygen, and the gas outlet pipe of the argon cylinder is connected to the gas inlet pipe of the catalyst tank for transporting the gasification catalyst to the combustion platform; A monitoring device, including a pressure sensor and a temperature sensor installed on the low-pressure burner, for respectively monitoring and displaying the pressure and temperature in the combustion reaction chamber in real time; The aerogel forming device is arranged above the low-pressure burner and connected to it, and includes a controller, a one-way solenoid valve and a forming tank body. A one-way solenoid valve is installed on the pipe connecting the forming tank body and the vacuum pump. The one-way solenoid valve is electrically connected to the controller, and the vacuum pump is connected to the low-pressure burner through a pipe.

[0007] As a further improvement of the present invention, the combustion reaction chamber is connected to the vacuum pump via a stainless steel bellows.

[0008] As a further improvement of the present invention, flow meters are respectively installed on the gas outlet pipes of the gaseous hydrocarbon cylinder, the oxygen cylinder and the argon cylinder.

[0009] As a further improvement of the present invention, the combustion platform includes a hollow tube and a catalyst injection tube nested in the wall of the hollow tube and a gas dispersion furnace plate arranged on the top of the hollow tube. The lower end of the hollow tube is provided with a premixing chamber, which is used to mix fuel and oxygen from gaseous hydrocarbon cylinders and oxygen cylinders respectively. The injection tube is used to introduce a gasification catalyst, and the furnace plate is used to further disperse the gas mixture.

[0010] As a further improvement of the present invention, the temperature adjustment range of the coated heating jacket of the catalyst feeding device is 200-400°C, and the argon inlet flow rate of the catalyst tank is 50-500 mL / min.

[0011] A method for preparing carbon nanotube aerogel comprises the following steps: 1) Dissolving the metal catalyst in an organic solvent to prepare a catalyst precursor solution; 2) Adjust the flow ratio of fuel to oxygen to establish a stable premixed flame and control the reaction chamber pressure at 40-50 kPa; 3) Adjust the heating temperature of the catalyst tank and the carrier gas flow rate, and introduce the gasification catalyst into the flame zone; 4) Adjust the height of the combustion platform so that the outer flame area is aligned with the tank inlet of the aerogel molding device; 5) The solenoid valve is controlled to open, and under the vacuum suction of the vacuum pump, the carbon nanotubes self-assemble in situ in the molding cavity of the molding tank to form aerogel.

[0012] As a further improvement of the present invention, the metal catalyst is one or more of ferric acetylacetonate, nickel acetylacetonate or cobalt acetylacetonate; and the organic solvent is a mixture of ethanol and acetone in a volume ratio of 1:1 to 10:1.

[0013] As a further improvement of the present invention, the fuel is gaseous hydrocarbon, the gaseous hydrocarbon is methane, ethylene, ethane or coalbed methane, and the flow ratio of the fuel to oxygen is 1:1 to 1:5.

[0014] The beneficial effects of the present invention are: 1. In-situ continuous growth and simplified process flow: This invention achieves in-situ growth of carbon nanotubes and simultaneous construction of a three-dimensional network structure under a low-pressure combustion environment, avoiding the complex dispersion, assembly, and drying steps of the traditional solution method and simplifying the preparation process of carbon nanotube aerogels; 2. Low energy consumption and environmentally friendly process: Compared with high-temperature pyrolysis and freeze-drying methods, the present invention uses combustion as the heat source. It not only self-sustains the heat required for the reaction, reducing external energy input, but also does not require the addition of surfactants or cross-linking agents, avoiding organic residues and solvent contamination; 3. Wide range of applications and flexible carbon sources: The present invention is applicable to a variety of gaseous hydrocarbon carbon sources, including methane, ethylene and ethane, and has strong adaptability, which is conducive to optimized configuration and industrial scale-up according to different raw materials and production conditions; 4. The device structure is highly integrated and has the potential for continuous production: The low-pressure combustion system constructed by the present invention integrates catalyst gasification, premixed combustion, temperature monitoring and aerogel capture functions. Through the linkage regulation of the combustion platform and the forming cavity, it realizes the controllable and continuous generation of carbon nanotube aerogel, and has good potential for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 Schematic diagram of the apparatus for preparing carbon nanotube aerogels for low-pressure combustion of gaseous hydrocarbons; Figure 2 This is a schematic diagram of the combustion platform structure; Figure 3 This is a physical picture of the carbon nanotube aerogel prepared in Example 1; Figure 4 This is the SEM image of the carbon nanotube aerogel prepared in Example 1; Figure 5 This is a TEM image of the carbon nanotube aerogel prepared in Example 2; Figure 6 This is a nitrogen adsorption-desorption curve of the carbon nanotube aerogel prepared in Example 3.

[0016] In the figure: 1. Low-pressure burner; 2. Combustion platform; 3. Catalyst tank; 4. Brushless motor; 5. Temperature sensor; 6. Pressure sensor; 7. Molded tank body; 8. Vacuum pump; 9. One-way solenoid valve; 10. Controller; 11. Flow meter; 12. Gaseous hydrocarbon cylinder; 13. Oxygen cylinder; 14. Argon cylinder; 15. Hollow tube; 16. Premixing chamber; 17. Catalyst injection tube; 18. Dispersion furnace plate. DETAILED DESCRIPTION

[0017] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0018] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0019] like Figure 1-2 As shown, a device for preparing carbon nanotube aerogel by low-pressure combustion of gaseous hydrocarbons comprises: The low-pressure burner 1 has a combustion reaction chamber inside; The combustion platform 2 is arranged inside the combustion reaction chamber, and its lower end is connected to the brushless motor 4 to achieve up and down reciprocating movement, which is used to generate a stable premixed flame; The catalyst feeding device comprises a catalyst tank 3 installed in a wrapped heating jacket, wherein the gas outlet pipe of the catalyst tank 3 is connected to the combustion platform 2; A gas supply device, including a gaseous hydrocarbon cylinder 12, an oxygen cylinder 13 and an argon cylinder 14, wherein the gas outlet pipes of the gaseous hydrocarbon cylinder 12 and the oxygen cylinder 13 are connected to the combustion platform 2 for providing fuel and oxygen, and the gas outlet pipe of the argon cylinder 14 is connected to the gas inlet pipe of the catalyst tank 3 for transporting the gasified catalyst to the combustion platform 2; The monitoring device includes a pressure sensor 6 and a temperature sensor 5 installed on the low-pressure burner 1, which are used to monitor and display the pressure and temperature in the combustion reaction chamber in real time; The aerogel molding device is arranged above the low-pressure burner 1 and connected thereto, and includes a controller 10, a one-way solenoid valve 9 and a molding tank body 7. The molding tank body 7 is a cylindrical structure with a hollow interior. A one-way solenoid valve 9 is installed on the pipe connecting the molding tank body 7 and the vacuum pump 8. The one-way solenoid valve 9 is electrically connected to the controller 10, and the vacuum pump 8 is connected to the low-pressure burner 1 through a pipe.

[0020] The combustion reaction chamber is connected to the vacuum pump 8 via a stainless steel bellows.

[0021] Flow meters 11 are installed on the gas outlet pipes of the gaseous hydrocarbon cylinder 12 , the oxygen cylinder 13 and the argon cylinder 14 , respectively.

[0022] The combustion platform 2 includes a hollow tube 15 and a catalyst injection tube 17 nested in the wall of the hollow tube 15 and a gas dispersion furnace plate 18 arranged on the top of the hollow tube 15. The lower end of the hollow tube 15 is provided with a premixing chamber 16. The premixing chamber 16 is used to mix the fuel and oxygen from the gaseous hydrocarbon cylinder 12 and the oxygen cylinder 13 respectively. The injection tube is used to introduce the gasification catalyst, and the furnace plate is used to further disperse the gas mixture.

[0023] The temperature adjustment range of the coated heating jacket of the catalyst feeding device is 200-400°C, and the argon inlet flow rate of the catalyst tank 3 is 50-500 mL / min.

[0024] All raw materials used in the embodiments of the present invention can be purchased commercially.

[0025] The active component precursor solution used in the embodiment of the present invention is prepared by mixing acetylacetonate of iron, cobalt or nickel at a solid-liquid ratio of 200 mg / mL with an ethanol / acetone mixture at a volume ratio of 1:1 to 10:1.

[0026] The technical solution of the present invention is further illustrated by the following examples.

[0027] Example 1 A method for preparing carbon nanotube aerogel using iron acetylacetonate as a catalyst and methane as a carbon source comprises the following steps: 1) Dissolve 1.0 g of ferric acetylacetonate in 40 mL of a 1:1 ethanol / acetone mixture and sonicate for 30 minutes to obtain a brownish-red, uniform catalyst precursor solution. Place the solution in a sealed stainless steel catalyst tank (3), install a heating mantle, and heat to 200°C. 2) Start vacuum pump 8 and adjust the combustion chamber pressure to 45 kPa. Set the methane to oxygen volume flow ratio to 1:3 and adjust flow meter 11 to establish a premixed flame. Set the height of combustion platform 2 so that the outer flame zone is 2 cm below the inlet of the molded tank 7.

[0028] 3) Introduce carrier gas argon with a flow rate controlled at 100 mL / min, start the catalyst feeding device, and cause the precursor to be atomized and enter the center area of ​​the flame through the injection pipe.

[0029] 4) Controller 10 signals to open one-way solenoid valve 9, activating vacuum pump 8 to generate negative pressure. The carbon nanotubes generated in the flame rapidly flow along the airstream into the molding tank 7. Within the molding tank 7, the pressure differential drives the carbon nanotubes to form C-C covalent bonds at their intersections, forming a strongly interconnected three-dimensional network. After approximately 30 minutes, the resulting black, lightweight mass is collected, representing the carbon nanotube aerogel.

[0030] Figure 3 This is a physical picture of the carbon nanotube aerogel prepared in step 4) of this embodiment. Figure 4 The SEM image of the resulting carbon nanotube aerogel shows a continuous pore structure and excellent electrical conductivity. The SEM image shows that it is composed of entangled and cross-linked carbon nanotubes, with an overall lightweight and uniform structure.

[0031] Example 2 A method for preparing carbon nanotube aerogel using nickel acetylacetonate as a catalyst and ethane as a carbon source comprises the following steps: 1) Dissolve 1.5 g of ferric acetylacetonate in 30 mL of a 2:1 ethanol / acetone mixture and sonicate for 30 minutes to obtain a green catalyst precursor solution. Place the solution in a sealed stainless steel catalyst tank (3), install a heating mantle, and heat to 320°C. 2) Start vacuum pump 8 and adjust the combustion chamber pressure to 40 kPa. Set the ethane to oxygen volume flow ratio to 1:4 and adjust flowmeter 11 to establish a premixed flame. Set the combustion platform 2 so that the outer flame zone is 2 cm below the inlet of the molded tank 7.

[0032] 3) Introduce carrier gas argon with a flow rate controlled at 300 mL / min, start the catalyst feeding device, and cause the precursor to be atomized and enter the center area of ​​the flame through the injection pipe.

[0033] 4) Controller 10 signals to open one-way solenoid valve 9, activating vacuum pump 8 to generate negative pressure. The carbon nanotubes generated in the flame rapidly flow along the airflow into the forming tank 7, where they self-assemble into a three-dimensional network. After approximately 30 minutes, the resulting black, lightweight mass is collected, representing the carbon nanotube aerogel.

[0034] Figure 5 This is a TEM image of the carbon nanotube aerogel prepared in step 4) of this example. The sample exhibits a highly ordered carbon nanotube structure, and the aerogel exhibits a sponge-like continuous network.

[0035] Example 3 A method for preparing carbon nanotube aerogel using a composite catalyst of cobalt acetylacetonate and iron acetylacetonate and ethylene as a carbon source comprises the following steps: 1) Weigh 0.5 g each of cobalt acetylacetonate and iron acetylacetonate in a 1:1 molar ratio and dissolve in a mixture of 15 mL of ethanol and 5 mL of acetone. Ultrasonicate for 30 minutes to obtain a dark brown solution. Transfer the mixture to catalyst tank 3 and heat to 400°C. 2) Start vacuum pump 8 and adjust the combustion chamber pressure to 50 kPa. Set the volumetric flow rate ratio of ethylene to oxygen to 1:1 and adjust flow meter 11 to establish a premixed flame. Set the height of combustion platform 2 so that the outer flame zone is 2 cm below the inlet of the molded tank 7.

[0036] 3) Introduce carrier gas argon with a flow rate controlled at 200 mL / min, start the catalyst feeding device, and cause the precursor to be atomized and enter the center area of ​​the flame through the injection pipe.

[0037] 4) Controller 10 signals to open one-way solenoid valve 9, activating vacuum pump 8 to generate negative pressure. The carbon nanotubes generated in the flame rapidly flow along the airflow into the forming tank 7, where they self-assemble into a three-dimensional network. After approximately 30 minutes, the resulting black, lightweight mass is collected, representing the carbon nanotube aerogel.

[0038] Figure 6 This is the nitrogen adsorption-desorption curve of the carbon nanotube aerogel prepared in step 4) of this embodiment. BET analysis shows that the specific surface area of ​​the sample is as high as 410m 2 / g, and the pore size distribution is concentrated in the range of 10-40nm, showing a good hierarchical pore structure.

[0039] Comparative data on carbon nanotube performance: The relevant performance test results of the carbon nanotube aerogels prepared in Examples 1-3 are shown in Table 1.

[0040] Table 1 Carbon nanotube performance results The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, improvements, component splits, or combinations, etc., that fall within the spirit and principles of the present invention, shall be included within the scope of protection of the present invention.

Claims

1. A device for preparing carbon nanotube aerogel by low-pressure combustion of gaseous hydrocarbons, characterized in that: include: A low-pressure burner, the interior of which is a combustion reaction chamber; The combustion platform is arranged inside the combustion reaction chamber, and its lower end is connected to a brushless motor to achieve up and down reciprocating movement, which is used to generate a stable premixed flame; The catalyst feeding device comprises a catalyst tank installed in a wrapped heating jacket, wherein the gas outlet pipe of the catalyst tank is connected to the combustion platform; A gas supply device, comprising a gaseous hydrocarbon cylinder, an oxygen cylinder and an argon cylinder, wherein the gas outlet pipes of the gaseous hydrocarbon cylinder and the oxygen cylinder are connected to the combustion platform for providing fuel and oxygen, and the gas outlet pipe of the argon cylinder is connected to the gas inlet pipe of the catalyst tank for transporting the gasification catalyst to the combustion platform; A monitoring device, including a pressure sensor and a temperature sensor installed on the low-pressure burner, for respectively monitoring and displaying the pressure and temperature in the combustion reaction chamber in real time; The aerogel forming device is arranged above the low-pressure burner and connected to it, and includes a controller, a one-way solenoid valve and a forming tank body. A one-way solenoid valve is installed on the pipe connecting the forming tank body and the vacuum pump. The one-way solenoid valve is electrically connected to the controller, and the vacuum pump is connected to the low-pressure burner through a pipe.

2. The device for preparing carbon nanotube aerogel by low-pressure combustion of gaseous hydrocarbons according to claim 1, characterized in that: The combustion reaction chamber is connected to a vacuum pump via a stainless steel bellows.

3. The device for preparing carbon nanotube aerogel by low-pressure combustion of gaseous hydrocarbons according to claim 1, characterized in that: Flow meters are respectively installed on the gas outlet pipes of the gaseous hydrocarbon cylinder, the oxygen cylinder and the argon cylinder.

4. The device for preparing carbon nanotube aerogel by low-pressure combustion of gaseous hydrocarbons according to claim 1, characterized in that: The combustion platform includes a hollow tube, a catalyst injection tube nested in the wall of the hollow tube, and a gas dispersion furnace plate arranged on the top of the hollow tube. The lower end of the hollow tube is provided with a premixing chamber, which is used to mix fuel and oxygen from gaseous hydrocarbon cylinders and oxygen cylinders respectively. The injection tube is used to introduce gasification catalyst, and the furnace plate is used to disperse the gas mixture.

5. The device for preparing carbon nanotube aerogel by low-pressure combustion of gaseous hydrocarbons according to claim 1, characterized in that: The temperature adjustment range of the coated heating jacket of the catalyst feeding device is 200-400°C, and the argon inlet flow rate of the catalyst tank is 50-500 mL / min.

6. A method for preparing carbon nanotube aerogel using the device according to claim 1, characterized in that: The following steps are involved: 1) Dissolving the metal catalyst in an organic solvent to prepare a catalyst precursor solution; 2) Adjust the flow ratio of fuel to oxygen to establish a stable premixed flame and control the reaction chamber pressure at 40-50 kPa; 3) Adjust the heating temperature of the catalyst tank and the carrier gas flow rate, and introduce the gasification catalyst into the flame zone; 4) Adjust the height of the combustion platform so that the outer flame area is aligned with the tank inlet of the aerogel molding device; 5) The solenoid valve is controlled to open, and under the vacuum suction of the vacuum pump, the carbon nanotubes self-assemble in situ in the molding cavity of the molding tank to form aerogel.

7. The method for preparing carbon nanotube aerogel according to claim 6, wherein: The metal catalyst is one or more of ferric acetylacetonate, nickel acetylacetonate or cobalt acetylacetonate; and the organic solvent is a mixture of ethanol and acetone in a volume ratio of 1:1 to 10:

1.

8. The method for preparing carbon nanotube aerogel according to claim 6, wherein: The fuel is gaseous hydrocarbon, which is methane, ethylene, ethane or coalbed methane. The flow ratio of the fuel to oxygen is 1:1 to 1:5.

Images