Apparatus and method for producing carbon nanotube aerogel by low pressure combustion of gaseous hydrocarbon

Abstract

The application belongs to the technical field of carbon nanotube aerogel preparation, and discloses a device and method for preparing carbon nanotube aerogel by gaseous hydrocarbon low-pressure combustion, which 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 low-pressure combustor is internally provided with a combustion reaction cavity, and the combustion platform is located in the combustion reaction cavity and moves up and down through a brushless motor; the catalyst feeding device vaporizes catalysts by using a heating jacket and transports the catalysts to the combustion platform by argon; the gas supply device provides gaseous hydrocarbon fuel, oxygen and carrier gas; the monitoring device monitors pressure and temperature in real time; and the aerogel forming device realizes in-situ self-assembly of carbon nanotubes through vacuum suction force. The application realizes continuous preparation of carbon nanotube aerogel by using a low-pressure combustion method, has the advantages of simple process, low energy consumption and high structural integration, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of carbon nanotube aerogel preparation technology, specifically relating to an apparatus and method for preparing carbon nanotube aerogel by low-pressure combustion of gaseous hydrocarbons. Background Technology

[0002] Carbon nanotubes, with their excellent electrical conductivity, ultra-large specific surface area, and superior mechanical properties, occupy an important position in fields such as energy storage devices, electrocatalysis, and electrothermal materials. Assembling carbon nanotubes into aerogels with a three-dimensional network structure can further enhance their structural stability and functional integration, showing broad application prospects in flexible electronics, supercapacitors, and thermal management materials.

[0003] Existing methods for preparing carbon nanotube aerogels mainly rely on solution assembly, template replication, or freeze-drying techniques, but these methods generally suffer from problems such as complex processes, high energy consumption, and difficulty in achieving continuous production. Combustion, as a heat-sustaining, efficient, and simple preparation method, uses gaseous hydrocarbons (such as methane, ethane, and ethylene) as a carbon source. Under the action of transition metal catalysts, it can achieve rapid growth of carbon nanotubes and simultaneously self-assemble into carbon nanotube-based aerogels under low-pressure conditions. Compared to traditional methods, combustion significantly reduces energy consumption and has 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 the continuous production of carbon nanotube aerogels with simple process, low energy consumption, and continuous operation has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide an apparatus and method for preparing carbon nanotube aerogels by low-pressure combustion of gaseous hydrocarbons. The apparatus has a high degree of structural integration, the method has simple steps, it can realize in-situ continuous growth of carbon nanotube aerogels, and it has low energy consumption, is environmentally friendly, and is suitable for industrial production.

[0006] To achieve the aforementioned objectives, the technical solution adopted is as follows:

[0007] An apparatus for preparing carbon nanotube aerogels by low-pressure combustion of gaseous hydrocarbons, comprising:

[0008] The low-pressure burner has a combustion reaction chamber inside.

[0009] The combustion platform is located inside the combustion reaction chamber, and its lower end is connected to a brushless motor to achieve reciprocating up and down movement, which is used to generate a stable premixed flame.

[0010] The catalyst feeding device includes a catalyst tank installed inside a covered heating jacket, and the gas outlet pipe of the catalyst tank is connected to the combustion platform;

[0011] The gas supply device includes a gaseous hydrocarbon cylinder, an oxygen cylinder, and an argon cylinder. The gas outlet pipes of the gaseous hydrocarbon cylinder and the oxygen cylinder are connected to the combustion platform to provide fuel and oxygen. The gas outlet pipe of the argon cylinder is connected to the gas inlet pipe of the catalyst tank to deliver the gasified catalyst to the combustion platform.

[0012] The monitoring device includes a pressure sensor and a temperature sensor installed on the low-pressure burner, which are used to monitor and display the pressure and temperature in the combustion reaction chamber in real time, respectively.

[0013] An aerogel molding device is installed above and connected to a low-pressure burner, including a controller, a one-way solenoid valve, and a molding tank. The one-way solenoid valve is installed on the pipe connecting the molding tank to the vacuum pump. The one-way solenoid valve is electrically connected to the controller. The vacuum pump is connected to the low-pressure burner through a pipe.

[0014] As a further improvement of the present invention, the combustion reaction chamber is connected to a vacuum pump via a stainless steel bellows.

[0015] As a further improvement of the present invention, flow meters are respectively installed on the outlet pipes of the gaseous hydrocarbon cylinder, oxygen cylinder and argon cylinder.

[0016] As a further improvement of the present invention, the combustion platform includes a hollow tube, a catalyst injection pipe nested on the wall of the hollow tube, and a gas dispersion furnace plate disposed 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 pipe is used to introduce a gasification catalyst, and the furnace plate is used to further disperse the gas mixture.

[0017] As a further improvement of the present invention, the temperature adjustment range of the enclosed heating jacket of the catalyst feeding device is 200-400°C, and the argon gas inlet flow rate of the catalyst tank is 50-500 mL / min.

[0018] A method for preparing carbon nanotube aerogels includes the following steps:

[0019] 1) Dissolve the metal catalyst in an organic solvent to prepare a catalyst precursor solution;

[0020] 2) Adjust the flow ratio of fuel to oxygen to establish a stable premixed flame and control the pressure in the reaction chamber at 40-50 kPa;

[0021] 3) Adjust the catalyst tank heating temperature and carrier gas flow rate to introduce the gasification catalyst into the flame zone;

[0022] 4) Adjust the height of the combustion platform so that the outer flame zone is aligned with the tank inlet of the aerogel molding device;

[0023] 5) Control the solenoid valve 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 an aerogel.

[0024] As a further improvement of the present invention, the metal catalyst is one or more of iron acetylacetonate, nickel acetylacetonate, or cobalt acetylacetonate; the organic solvent is a mixture of ethanol and acetone in a volume ratio of 1:1 to 10:1.

[0025] As a further improvement of the present invention, the fuel is a gaseous hydrocarbon, such as methane, ethylene, ethane or coalbed methane, and the flow ratio of the fuel to oxygen is 1:1 to 1:5.

[0026] The beneficial effects of this invention are:

[0027] 1. In-situ continuous growth, simplified process flow: This invention achieves in-situ growth of carbon nanotubes and simultaneous construction of three-dimensional network structure under low-pressure combustion environment, avoiding the complex dispersion, assembly and drying steps in traditional solution method, and simplifying the preparation process of carbon nanotube aerogel.

[0028] 2. Low energy consumption and green and environmentally friendly process: Compared with high-temperature pyrolysis and freeze drying, the present invention uses combustion as a heat source, which not only sustains the heat required for the reaction and reduces external energy input, but also eliminates the need to add surfactants or crosslinking agents, thus avoiding organic residues and solvent pollution.

[0029] 3. Wide range of applications and flexible carbon sources: This invention is applicable to a variety of gaseous hydrocarbon carbon sources, including methane, ethylene and ethane. It is highly adaptable and can be optimized and scaled up industrially according to different raw materials and production conditions.

[0030] 4. The device has a high degree of structural integration and has the potential for continuous production: The low-pressure combustion system constructed by this invention integrates catalyst gasification, premixed combustion, temperature monitoring and aerogel capture functions. Through the linkage and control of the combustion platform and the forming cavity, the controllable and continuous generation of carbon nanotube aerogels can be achieved, which has good potential for large-scale production. Attached Figure Description

[0031] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 A schematic diagram of an apparatus for preparing carbon nanotube aerogels by low-pressure combustion of gaseous hydrocarbons;

[0033] Figure 2 This is a schematic diagram of the combustion platform structure;

[0034] Figure 3This is a photograph of the carbon nanotube aerogel prepared in Example 1.

[0035] Figure 4 SEM image of the carbon nanotube aerogel prepared in Example 1;

[0036] Figure 5 This is a TEM image of the carbon nanotube aerogel prepared in Example 2;

[0037] Figure 6 The graph shows the nitrogen adsorption-desorption curves of the carbon nanotube aerogel prepared in Example 3.

[0038] In the diagram: 1. Low-pressure burner; 2. Combustion platform; 3. Catalyst tank; 4. Brushless motor; 5. Temperature sensor; 6. Pressure sensor; 7. Molded tank; 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 pipe; 18. Dispersion furnace plate. Detailed Implementation

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

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

[0041] like Figure 1-2 As shown, an apparatus for preparing carbon nanotube aerogels by low-pressure combustion of gaseous hydrocarbons includes:

[0042] Low-pressure burner 1, the interior of which is a combustion reaction chamber;

[0043] Combustion platform 2 is located inside the combustion reaction chamber, and its lower end is connected to brushless motor 4 to achieve reciprocating up and down movement, which is used to generate a stable premixed flame.

[0044] The catalyst feeding device includes a catalyst tank 3 installed inside a covered heating jacket, and the gas outlet pipe of the catalyst tank 3 is connected to the combustion platform 2.

[0045] The gas supply device includes a gaseous hydrocarbon cylinder 12, an oxygen cylinder 13, and an argon cylinder 14. The gas outlet pipes of the gaseous hydrocarbon cylinder 12 and the oxygen cylinder 13 are connected to the combustion platform 2 to provide fuel and oxygen. The gas outlet pipe of the argon cylinder 14 is connected to the gas inlet pipe of the catalyst tank 3 to transport the gasified catalyst to the combustion platform 2.

[0046] 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, respectively.

[0047] An aerogel molding device is installed above and connected to a low-pressure burner 1, including a controller 10, a one-way solenoid valve 9, and a molding tank 7. The molding tank 7 is a hollow cylindrical structure. A one-way solenoid valve 9 is installed on the pipe connecting the molding tank 7 and the vacuum pump 8. The one-way solenoid valve 9 is electrically connected to the controller 10. The vacuum pump 8 is connected to the low-pressure burner 1 through a pipe.

[0048] The combustion reaction chamber is connected to the vacuum pump 8 via a stainless steel bellows.

[0049] Flow meters 11 are installed on the outlet pipes of the gaseous hydrocarbon cylinder 12, oxygen cylinder 13 and argon cylinder 14 respectively.

[0050] The combustion platform 2 includes a hollow tube 15, a catalyst injection pipe 17 nested in the wall of the hollow tube 15, and a gas dispersion furnace plate 18 set on the top of the hollow tube 15. The lower end of the hollow tube 15 is provided with a premixing chamber 16, which is used to mix fuel and oxygen from gaseous hydrocarbon cylinder 12 and oxygen cylinder 13 respectively. The injection pipe is used to introduce gasification catalyst, and the furnace plate is used to further disperse the gas mixture.

[0051] The temperature adjustment range of the enclosed heating jacket of the catalyst feeding device is 200-400°C, and the argon gas inlet flow rate of the catalyst tank 3 is 50-500 mL / min.

[0052] All raw materials used in the embodiments of this invention can be purchased commercially.

[0053] The active component precursor solution used in the embodiments of the present invention is prepared by mixing iron, cobalt or nickel acetylacetone salts with an ethanol / acetone mixture at a material-to-liquid ratio of 200 mg / mL and a volume ratio of 1:1 to 10:1.

[0054] The technical solution of the present invention will be further illustrated by the following embodiments.

[0055] Example 1

[0056] A method for preparing carbon nanotube aerogels using acetylacetone iron as a catalyst and methane as a carbon source includes the following steps:

[0057] 1) Dissolve 1.0 g of ferric acetylacetone in 40 mL of a 1:1 volume ratio ethanol / acetone mixture and sonicate for 30 min to obtain a brownish-red homogeneous catalyst precursor solution. Pour the solution into a sealed stainless steel catalyst container 3 and install a heating jacket; heat to 200°C.

[0058] 2) Start vacuum pump 8 and adjust the pressure in the combustion reaction chamber to 45 kPa; set the volumetric flow rate ratio of methane to oxygen to 1:3, and establish a premixed flame after adjusting flow meter 11. Set the height of combustion platform 2 so that the outer flame zone is located 2 cm below the inlet of molding tank 7.

[0059] 3) Introduce carrier gas argon at a flow rate of 100 mL / min, start the catalyst feeder, and promote the atomization of the precursor and its entry into the center of the flame through the injection pipe.

[0060] 4) Adjust the signal of controller 10 to open one-way solenoid valve 9 and start vacuum pump 8 to draw in negative pressure. The carbon nanotubes generated in the flame quickly enter the forming tank 7 along the airflow. In the forming tank 7, the carbon nanotubes form C-C covalent bonds at the intersection points driven by the pressure difference, forming a strongly connected three-dimensional network. After about 30 minutes, the black lightweight block obtained is collected, which is carbon nanotube aerogel.

[0061] Figure 3 This is a photograph of the carbon nanotube aerogel prepared in step 4) of this embodiment. Figure 4 The image shows a SEM image of the obtained carbon nanotube aerogel. The aerogel exhibits a continuous pore structure and excellent electrical conductivity. The SEM image shows that it is composed of entangled and cross-linked carbon nanotubes, and the overall structure is lightweight and uniform.

[0062] Example 2

[0063] A method for preparing carbon nanotube aerogels using nickel acetylacetone as a catalyst and ethane as a carbon source includes the following steps:

[0064] 1) Dissolve 1.5g of ferric acetylacetone in 30mL of a 2:1 (v / v) ethanol / acetone mixture and sonicate for 30min to obtain a green catalyst precursor solution. Pour the solution into a sealed stainless steel catalyst container 3 and install a heating jacket; heat to 320°C.

[0065] 2) Start vacuum pump 8 and adjust the pressure in the combustion reaction chamber to 40 kPa; set the volumetric flow rate ratio of ethane to oxygen to 1:4, and establish a premixed flame after adjusting flow meter 11. Set the height of combustion platform 2 so that the outer flame zone is located 2 cm below the inlet of molding tank 7.

[0066] 3) Introduce carrier gas argon at a flow rate of 300 mL / min, start the catalyst feeder, and promote the atomization of the precursor and its entry into the center of the flame through the injection pipe.

[0067] 4) Adjust the signal of controller 10 to open one-way solenoid valve 9 and start vacuum pump 8 to draw in negative pressure. The carbon nanotubes generated in the flame quickly enter the molding tank 7 along the airflow and self-assemble into a three-dimensional network structure. After about 30 minutes, the black lightweight block obtained is carbon nanotube aerogel.

[0068] Figure 5 This is a TEM image of the carbon nanotube aerogel prepared in step 4) of this embodiment. The sample shows a highly ordered carbon nanotube structure, and the aerogel shows a sponge-like continuous network.

[0069] Example 3

[0070] A method for preparing carbon nanotube aerogels using a cobalt acetylacetone and iron acetylacetone composite catalyst and ethylene as the carbon source includes the following steps:

[0071] 1) Weigh 0.5 g each of cobalt acetylacetonate and iron acetylacetonate in a 1:1 molar ratio, dissolve them in a mixed solvent of 15 mL ethanol and 5 mL acetone, and sonicate for 30 min to obtain a dark brown solution. Transfer the solution to catalyst container 3 and heat to 400°C;

[0072] 2) Start vacuum pump 8 and adjust the pressure in the combustion reaction chamber to 50 kPa; set the volumetric flow rate ratio of ethylene to oxygen to 1:1, and establish a premixed flame after adjusting flow meter 11. Set the height of combustion platform 2 so that the outer flame zone is located 2 cm below the inlet of molding tank 7.

[0073] 3) Introduce carrier gas argon at a flow rate of 200 mL / min, start the catalyst feeder, and promote the atomization of the precursor and its entry into the center of the flame through the injection pipe.

[0074] 4) Adjust the signal of controller 10 to open one-way solenoid valve 9 and start vacuum pump 8 to draw in negative pressure. The carbon nanotubes generated in the flame quickly enter the molding tank 7 along the airflow and self-assemble into a three-dimensional network structure. After about 30 minutes, the black lightweight block obtained is carbon nanotube aerogel.

[0075] Figure 6 The image shows the nitrogen adsorption-desorption curve of the carbon nanotube aerogel prepared in step 4) of this embodiment. BET analysis shows that the sample has a specific surface area as high as 410 m². 2 / g, with pore size distribution concentrated in the range of 10-40nm, exhibiting a good hierarchical pore structure.

[0076] Comparison of carbon nanotube performance data: The test results of relevant properties of carbon nanotube aerogels prepared in Examples 1-3 are shown in Table 1.

[0077] Table 1. Performance results of carbon nanotubes

[0078]

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, component splitting or combination, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An apparatus for preparing carbon nanotube aerogels by low-pressure combustion of gaseous hydrocarbons, characterized in that, include: The low-pressure burner has a combustion reaction chamber inside. A combustion platform, located inside the combustion reaction chamber, includes a hollow tube, a catalyst injection pipe nested in the wall of the hollow tube, and a gas dispersion furnace plate located at the top of the hollow tube. A premixing chamber is provided at the lower end of the hollow tube, used to mix fuel and oxygen from gaseous hydrocarbon cylinders and oxygen cylinders, respectively. The injection pipe is used to introduce a gasification catalyst, and the furnace plate is used to disperse the gas mixture. A brushless motor is connected to the lower end of the combustion platform to enable reciprocating up-and-down movement, used to adjust the height of the combustion platform so that the outer flame zone is aligned with the tank inlet of the aerogel molding device. The catalyst feeding device includes a catalyst tank installed inside a covered heating jacket, the gas outlet pipe of the catalyst tank being connected to the combustion platform, the temperature adjustment range of the covered heating jacket being 200–400°C, and the argon gas inlet flow rate of the catalyst tank being 50–500 mL / min. The gas supply device includes a gaseous hydrocarbon cylinder, an oxygen cylinder, and an argon cylinder. The gas outlet pipes of the gaseous hydrocarbon cylinder and the oxygen cylinder are connected to the combustion platform to provide fuel and oxygen. The gas outlet pipe of the argon cylinder is connected to the gas inlet pipe of the catalyst tank to deliver the gasification catalyst to the combustion platform. The monitoring device includes a pressure sensor and a temperature sensor installed on the low-pressure burner, which are used to monitor and display the pressure and temperature in the combustion reaction chamber in real time, respectively; the pressure in the combustion reaction chamber is controlled at 40-50 kPa. An aerogel forming device is disposed above and connected to the low-pressure burner, including a controller, a one-way solenoid valve and a forming tank. The one-way solenoid valve is installed on the pipe connecting the forming tank and the vacuum pump. The one-way solenoid valve is electrically connected to the controller. The vacuum pump is connected to the low-pressure burner through a pipe. Under the vacuum suction of the vacuum pump, the forming tank is used to enable carbon nanotubes to self-assemble in situ in its forming cavity to form aerogel.

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

4. A method for preparing carbon nanotube aerogels using the apparatus as described in claim 1, characterized in that, Includes the following steps: 1) Dissolve the metal catalyst in an organic solvent to prepare a catalyst precursor solution; the metal catalyst is one or more of iron acetylacetonate, nickel acetylacetonate, or cobalt acetylacetonate; the organic solvent is a mixture of ethanol and acetone in a volume ratio of 1:1 to 10:

1. 2) Adjust the flow ratio of fuel to oxygen to establish a stable premixed flame and control the pressure in the reaction chamber at 40-50 kPa; the fuel is a gaseous hydrocarbon, which is methane, ethylene, ethane or coalbed methane, and the flow ratio of fuel to oxygen is 1:1 to 1:

5. 3) Adjust the heating temperature of the catalyst tank and the flow rate of the carrier gas, and introduce the gasification catalyst into the flame zone; the heating temperature of the catalyst tank is 200-400°C, and the flow rate of the carrier gas argon is 50-500 mL / min; 4) Adjust the height of the combustion platform so that the outer flame zone is aligned with the tank inlet of the aerogel molding device; 5) Control the opening of the solenoid valve. 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 an aerogel. The carbon nanotubes form C-C covalent bonds at the intersection of the carbon nanotubes through pressure difference, forming a strongly connected three-dimensional network.

Images