A device for synthesizing graphene by coupling carbon dioxide with magnesium-based metal

Abstract

The utility model relates to carbon nanometer material preparation equipment technical field, concretely is a device for carbon dioxide coupling magnesium base metal synthesis graphene. The device includes reactor main body, gas supply system, temperature control system, ultrasonic treatment system and vacuum sealing system. Reactor main body adopts three layer structure: the outer layer is stainless steel shell, the middle is heat preservation layer, and the inner lining is silicon nitride ceramic lining; gas supply system evenly disperses CO2 through porous aeration disc; temperature control system realizes zoning temperature control; ultrasonic treatment system restrains graphene stacking. The utility model solves the problem that CO2 and magnesium melt contact unevenly, temperature fluctuation is big and the like in ton level production, makes the proportion that graphene layer number is less than 10 stable greater than 60%, and carbon source utilization rate is greater than or equal to 85%. The device structure is reasonable, and easy to scale, is applicable to high temperature melting reaction system.

Description

Technical Field

[0001] This utility model belongs to the technical field of carbon resource utilization and carbon nanomaterial preparation equipment. Specifically, it relates to a special reaction device for synthesizing graphene by coupling carbon dioxide with magnesium-based metals. It is particularly suitable for the in-situ reaction of CO2 with magnesium-based metals under large-scale, high-temperature molten conditions, and can efficiently prepare high-quality graphene. Background Technology

[0002] This utility model relates to the technical field of carbon nanomaterial preparation equipment, specifically to a device for synthesizing graphene by coupling magnesium-based metals with carbon dioxide.

[0003] Graphene, due to its unique single-atom-layer two-dimensional crystal structure, exhibits excellent properties in thermal, mechanical, and electrical fields, and has broad application prospects. Currently, the main methods for preparing graphene include micromechanical exfoliation, epitaxial growth, chemical vapor deposition (CVD), and graphene oxide reduction. However, these methods all have certain limitations: micromechanical exfoliation is inefficient and difficult to scale up; epitaxial growth requires expensive equipment and has demanding preparation conditions; CVD is costly and the graphene transfer process is complex; and redox methods easily introduce structural defects and generate wastewater pollution.

[0004] In recent years, the process of preparing graphene by reacting magnesium-based metals with carbon dioxide has attracted attention. However, the large-scale application of this process is limited by design flaws in the reaction apparatus. First, existing reactors mostly employ simple crucible structures with crude carbon dioxide introduction methods, such as aeration through straight pipes or single points. This results in uneven gas distribution in the magnesium melt, excessively large bubble sizes (typically greater than 1 mm), and a small gas-liquid contact area, leading to incomplete reaction between carbon dioxide and the magnesium melt and generally low carbon source utilization, reaching only 50% to 60%. Second, the temperature control precision during the reaction process is insufficient. Traditional heating methods are slow to respond and difficult to maintain the optimized reaction temperature (e.g., 750℃ ± 5℃), with temperature fluctuations often exceeding ± 20℃. This instability not only reduces reaction efficiency but also makes the generated graphene sheets prone to stacking and agglomeration, resulting in a proportion with more than 10 layers exceeding 50% and introducing more structural defects. Furthermore, existing devices lack effective integrated design. Ultrasonic processing systems are usually external units and cannot work in conjunction with the reaction process. Additionally, poor vacuum sealing performance may lead to air residue, oxidizing the magnesium melt and introducing impurities.

[0005] In summary, existing technologies have significant shortcomings in gas dispersion, temperature control, and system integration, which restrict the large-scale preparation of high-quality graphene. Therefore, there is an urgent need to develop a novel dedicated reaction device to solve the above-mentioned technical problems and achieve efficient and stable synthesis of high-quality graphene by carbon dioxide coupled with magnesium-based metals. Utility Model Content

[0006] The purpose of this invention is to overcome the technical deficiencies of existing reaction devices and provide a device for synthesizing graphene using carbon dioxide coupled with magnesium-based metals. Specifically, by optimizing structural dimensions and system integration, uniform contact between CO2 and magnesium melt, precise temperature control, and ultrasonic-assisted dispersion are achieved.

[0007] The device includes a reactor body, a gas supply system, a temperature control system, an ultrasonic treatment system, and a vacuum sealing system.

[0008] First, the reactor body adopts a three-layer structure design, consisting of a reactor shell, an insulation layer, and a silicon nitride ceramic lining from the outside in. The reactor shell serves as the supporting structure, with a total height of 950mm and an outer diameter of 830mm; the insulation layer is made of high-alumina insulation cotton with a thickness of 120mm; and the silicon nitride ceramic lining serves as the reaction chamber, with an inner diameter of 500mm, a height of 700mm, and a thickness of 25mm.

[0009] Secondly, the gas supply system includes a protective gas inlet pipe and a carbon dioxide inlet pipe. Specifically, the carbon dioxide inlet pipe is connected in series with a mass flow controller to control the CO2 flow rate at 0.995 m³ / min; the protective gas inlet pipe is connected to a gas mixing system to control the CO2 to SF6 volume ratio at 40:1.

[0010] Furthermore, a porous aeration disc with a diameter of 400 mm and a pore size of 80 μm is connected to the end of the gas supply system to ensure uniform gas dispersion.

[0011] Furthermore, the temperature control system includes an induction heating coil and multiple thermocouples. The induction heating coil has a power of 100kW, is divided into 4 temperature control zones, and surrounds the outside of the reactor shell; the multiple thermocouples are arranged along the axial direction to monitor temperature fluctuations in real time and control them within ±5℃.

[0012] Furthermore, it also includes an ultrasonic processing system, which includes an ultrasonic probe. Specifically, the ultrasonic probe has a power of 1.5kW and a diameter of 40mm, and is vertically inserted into the reactor through a flange sealing cover to an immersion depth of 20-30mm.

[0013] The vacuum sealing system includes a flange sealing cover and a vacuum extraction pipe. Specifically, the flange sealing cover uses a graphite gasket for sealing, and the vacuum extraction pipe ensures a vacuum level of <10 Pa within the reactor. Finally, the entire device is supported on a reactor base, forming a complete reaction system.

[0014] The advantages of this invention are as follows: First, the reaction parameters are precisely controllable, ensuring that the proportion of graphene layers with fewer than 10 is consistently greater than 60%; second, it has good industrial adaptability, with a single unit processing capacity of 50-100 kg / batch; and finally, it is green and economical, with a CO2 carbon source utilization rate of ≥85%, achieving efficient and stable graphene preparation. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings.

[0016] Figure 1 This is a front cross-sectional view of the device, which clearly shows the structural relationship and integrated design of the various components.

[0017] Figure 2 This is a top view of the porous aeration disc, showing the array of micropores on its surface.

[0018] Figure 1 Symbol explanation.

[0019] 1. Reactor shell; 2. Insulation layer; 3. Silicon nitride ceramic lining; 4. Induction heating coil; 5. Flange sealing cover; 6. Reactor base; 7. Multi-point thermocouple; 8. Porous aeration disc; 9. Protective gas inlet pipe; 10. Carbon dioxide inlet pipe; 11. Vacuum extraction pipe; 12. Ultrasonic probe. Detailed Implementation

[0020] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited thereto. Example 1

[0021] Raw material input: Add 80 kg of 99.99% pure Mg ingots to the silicon nitride ceramic lining, cover with the flange sealing cover, and close all air inlet valves.

[0022] Vacuum removal: Start the vacuum pump unit and evacuate the cavity to a vacuum level of 5 Pa through the vacuum evacuation pipe, and maintain it for 10 minutes.

[0023] Protective gas introduction: Open the valve of the protective gas inlet pipe to introduce CO2 / SF6 mixture into the cavity until the cavity pressure reaches 0.05MPa.

[0024] Magnesium melting: Start the induction heating coil, raise the temperature to 720℃, hold for 30 minutes to completely melt the Mg, and then cool down to 700℃ (monitored by multiple thermocouples, with temperature fluctuations of ±3℃).

[0025] In-situ reaction: Open the valve of the carbon dioxide inlet pipe, and CO2 is introduced into the melt through the porous aeration plate. At the same time, start the ultrasonic probe (preheated to 500℃, immersion depth 25mm), adjust the induction heating to 750℃, and ultrasonically treat for 60min.

[0026] Post-processing: After water quenching, the blocky composite material inside the lining was removed, crushed (particle size <1mm), acid-washed with 20% H2SO4 (80℃, 4h), plate and frame filter press, and vacuum dried at 120℃ to obtain graphene powder. Product testing showed that graphene with <10 layers accounted for 68%, and the carbon source utilization rate was 85%. Example 2

[0027] The mass flow controller of the carbon dioxide inlet pipe was adjusted to 0.95 m³ / min, and the ultrasonic probe power was 1 kW. Other parameters and operating procedures were the same as in Example 1. Product testing showed that graphene with fewer than 10 layers accounted for 62%, and the carbon source utilization rate was 85%. Example 3

[0028] The mass flow controller of the carbon dioxide inlet pipe was adjusted to 1.05 m³ / min, and the ultrasonic probe power was 2 kW. Other parameters and operating procedures were the same as in Example 1. Product testing showed that graphene with fewer than 10 layers accounted for 65%, and the carbon source utilization rate was 86%.

[0029] This utility model device, through integrated design, achieves highly efficient operation of high-temperature melting reaction and is suitable for ton-scale production. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this utility model should be included within the protection scope of this utility model.

Claims

1. An apparatus for synthesizing graphene using carbon dioxide coupled with magnesium-based metals, characterized in that, It includes the reactor body, gas supply system, temperature control system, ultrasonic treatment system, and vacuum sealing system.

2. The apparatus according to claim 1, characterized in that, The reactor body consists of a reactor shell, an insulation layer, and a silicon nitride ceramic lining, from the outside to the inside. The reactor shell has a total height of 950 mm and an outer diameter of 830 mm. The silicon nitride ceramic lining has an inner diameter of 500 mm, a height of 700 mm, and a thickness of 25 mm. The insulation layer is made of high-alumina insulation cotton with a thickness of 120 mm.

3. The apparatus according to claim 1, characterized in that, The gas supply system includes a protective gas inlet pipe and a carbon dioxide inlet pipe. The carbon dioxide inlet pipe is connected in series with a mass flow controller to control the CO2 flow rate at 0.995 m³ / min. The protective gas inlet pipe is connected to a gas mixing system to control the CO2 to SF6 volume ratio at 40:

1. The gas supply system is connected to a porous aeration disc at the end. The porous aeration disc has a diameter of 400 mm and a pore size of 80 μm.

4. The apparatus according to claim 1, characterized in that, The temperature control system includes an induction heating coil and a multi-point thermocouple. The induction heating coil has a power of 100kW, is divided into 4 temperature control zones, and surrounds the outside of the reactor shell.

5. The apparatus according to claim 1, characterized in that, The ultrasonic processing system includes an ultrasonic probe with a power of 1.5kW and a diameter of 40mm. The probe is vertically inserted into the reactor to a depth of 20-30mm, and its surface can be preheated to 500℃ to avoid thermal shock damage.

6. The apparatus according to claim 1, characterized in that, The vacuum sealing system includes a flange sealing cover and a vacuum extraction pipe to ensure that the vacuum degree inside the reactor is <10Pa; the entire device is supported on the reactor base.

7. The apparatus according to claim 3, characterized in that, The porous aeration discs are evenly distributed at the bottom of the reactor, with a distance of ≥50mm between them and the inner wall of the silicon nitride ceramic lining, ensuring that CO2 gas is evenly dispersed in the magnesium melt in the form of microbubbles.

8. The apparatus according to claim 4, characterized in that, The zoned temperature control of the induction heating coil, linked with multi-point thermocouples, controls the reaction temperature fluctuation within ±5℃, and is suitable for a reaction temperature range of 720-750℃.

9. The apparatus according to claim 6, characterized in that, The vacuum extraction pipe has an inner diameter of 20mm and is connected to a vacuum pump. The extraction rate is ≥10L / s, which can reduce the pressure inside the reactor to <10Pa within 5 minutes.

10. The apparatus according to claim 3, characterized in that, The protective gas mixing system uses a mass flow meter to precisely control the ratio of CO2 to SF6, with an error of ≤1%.

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