System for continuously and efficiently preparing two-dimensional carbon material by microwave method

Abstract

The utility model discloses a system for continuously and efficiently preparing a two-dimensional carbon material by a microwave method. The system comprises a microwave suppression tube and a high-power microwave unit which are obliquely arranged and communicated, microwave suppression structures are arranged at two ends of the high-power microwave unit; and a discharge section is arranged at the tail end of the preparation system. The bottom of the discharging section is communicated with a receiving bin, and the top of the discharging section is communicated with an exhaust section; the high-power microwave unit is provided with a high-power microwave receiving cavity, and a microwave expansion area is arranged in the high-power microwave receiving cavity; the device further comprises a conveying pipe, a rotating unit and a tail gas treatment unit, and the conveying pipe is obliquely arranged, sequentially penetrates through the microwave suppression pipe and the microwave expansion area and then extends to the discharging section. The conveying pipe is loaded on the rotating unit and can be driven by the rotating unit to rotate along the axis of the conveying pipe; the exhaust end of the exhaust section communicates with the tail gas treatment unit. The microwave device main body and the conveying pipe are obliquely arranged and are matched with the rotating unit to drive the conveying pipe to rotate at a constant speed, so that continuous, stable and uniform feeding operation can be realized, and the quality of two-dimensional carbon material finished products is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of two-dimensional carbon material preparation, and in particular to a system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method. Background Art

[0002] Two-dimensional carbon materials, including graphene, graphene oxide, expanded graphite (EG), etc.

[0003] Graphene, a two-dimensional carbon material composed of carbon atoms arranged in a hexagonal honeycomb lattice using sp² hybrid orbitals, possesses excellent optical, electrical, mechanical, and thermal properties, making it widely used in battery electrode materials, semiconductor devices, transparent displays, sensors, capacitors, transistors, and other fields. Due to its exceptional properties and potential applications, a series of significant advances have been made in numerous disciplines, including chemistry, materials science, physics, biology, environment science, and energy science.

[0004] Mainstream graphene production methods include the graphite oxide reduction method (Hummers method) and chemical vapor deposition (CVD method). The Hummers method first oxidizes graphite into graphite oxide using strong oxidants such as concentrated sulfuric acid, concentrated nitric acid, and potassium permanganate. This is then exfoliated into graphene oxide through ultrasonic treatment. Graphene oxide is then purified and reduced through dialysis to produce graphene powder. The Hummers method suffers from long process cycles and severe pollution, and the resulting graphene exhibits numerous defects and poor quality, limiting its application in high-end applications. While graphene produced by the CVD method is high-quality, it suffers from complex processes and high costs, making it difficult to commercialize on a large scale.

[0005] Microwave exfoliation of graphene utilizes the enormous energy released by microwave vaporization to exfoliate graphite sheets. This method is highly efficient and environmentally friendly, demonstrating significant potential for large-scale, rapid graphene production.

[0006] Graphene oxide (GO) is a layered graphite oxide composed of isolated monolayers of graphene with interstitial spaces between them. This gives it a large surface area, providing abundant reaction sites for various physical and chemical processes. Graphene oxide possesses excellent physical, chemical, optical, and electrical properties. Furthermore, due to the coexistence of multiple oxygen-containing functional groups on the basal plane and edges of the graphene sheet skeleton, its conductivity and band gap can be modulated by adjusting the type and quantity of oxygen-containing functional groups. This material has a wide range of applications. Graphene oxide is a new carbon material with excellent properties, boasting a high surface area and abundant surface functional groups. Graphene oxide composites, including polymer composites and inorganic composites, have a wide range of applications.

[0007] Early methods for preparing graphene oxide primarily relied on chemical oxidation methods, including the Brodie, Staudenmaier, and Hummers methods. The Brodie method, the earliest reported method for preparing graphene oxide, utilizes fuming nitric acid and potassium chlorate to oxidize graphite. However, this method is highly reactive, prone to explosion hazards, and poses significant environmental risks. The Staudenmaier method, an improvement on the Brodie method, utilizes a mixture of concentrated sulfuric acid and fuming nitric acid, along with potassium chlorate, to oxidize graphite. While this method improves the degree of oxidation, it still presents safety and environmental concerns. The Hummers method, using concentrated sulfuric acid, sodium nitrate, and potassium permanganate as oxidants, is relatively safer and milder, and has become one of the most commonly used methods for preparing graphene oxide. However, the oxidants used in this method still pose significant environmental risks.

[0008] Microwave exfoliation of graphene oxide utilizes the enormous energy released by microwave vaporization to exfoliate graphene oxide sheets. This method offers significant advantages, including high efficiency, environmental friendliness, selective heating, and ease of functionalization, demonstrating significant potential for large-scale, rapid graphene production.

[0009] Expanded graphite (EG) is obtained by intercalating and expanding natural flake graphite. Microscopically, it has a worm-like morphology. Its basic structural unit is graphite flakes, which are stretched apart along the interlayer direction by the gas generated by the thermal decomposition of the intercalating material. In three-dimensional space, numerous graphite flakes intersect and overlap, forming a large number of irregular pores. These pores vary in size and are interconnected, giving expanded graphite a loose and porous nature, resulting in a large specific surface area, which is advantageous in many applications such as adsorption and filtration.

[0010] In the existing microwave carbon material production process, there is still much room for optimization in the structural design of the preparation equipment. Conventional preparation equipment uses pneumatic conveying for horizontal feeding, which leads to uneven heating of the material in the microwave reactor and affects the quality of graphite-related products (the degree of expansion and thermal peeling). The design for suppressing microwave leakage also needs to be strengthened. Utility Model Content

[0011] The purpose of the present utility model is to solve one of the technical problems in the related art to a certain extent at least. In view of this, a system for continuously and efficiently preparing two-dimensional carbon materials by microwave method is provided, comprising a microwave suppression tube and a high-power microwave unit which are arranged obliquely and connected; the end of the high-power microwave unit away from the microwave suppression tube is connected to a discharge section, the bottom of the discharge section is connected to a receiving bin, and the top of the discharge section is connected to an exhaust section; the high-power microwave unit is provided with a high-power microwave receiving cavity, and a microwave expansion zone is provided in the high-power microwave receiving cavity; the device also includes a feed pipe, a rotating unit and an exhaust gas treatment unit, the feed pipe is arranged obliquely and passes through the microwave suppression tube and the microwave expansion zone in sequence and then extends to the discharge section, the feed pipe is loaded on the rotating unit and can be driven by the rotating unit to rotate along the axis of the feed pipe, and the exhaust end of the exhaust section is connected to the exhaust treatment unit.

[0012] According to an example of the present invention, the portion of the feed pipe located inside the microwave expansion zone is an expansion pipe section, and the expansion pipe section is a variable diameter tubular structure with a diameter gradually increasing from the feed side toward the discharge side.

[0013] According to an example of the present invention, the inclination angle of the conveying pipe relative to the horizontal plane is 5°~80°.

[0014] According to an example of the present invention, a reflective focusing plate is provided at the bottom corner of the high-power microwave receiving cavity, and the reflective focusing plate is arranged toward the feed pipe in the high-power microwave receiving cavity to drive the microwave energy to concentrate toward the center of the high-power microwave receiving cavity and form a high microwave power area in a local narrow space.

[0015] According to an example of the present invention, the high-power microwave unit includes a microwave generator with a frequency of 915 MHz or 2450 MHz, and the power of the microwave generator is 1 kW to 100 kW; when the microwave generator is in steady-state operation, the material in the conveying pipe can form a local high-temperature environment of 300° to 1000° within 0 to 2 seconds when passing through the microwave expansion zone.

[0016] According to an example of the present invention, an infrared temperature measurement module is provided on the high-power microwave receiving cavity for monitoring the temperature in the microwave expansion zone.

[0017] According to an example of the present invention, a screen is installed in one end of the exhaust section close to the discharging section, and a microwave suppression grid is installed between the screen and the exhaust section. The microwave suppression grid has a plurality of grid plates arranged vertically and horizontally, and the gaps between the grid plates extend in the same direction as the exhaust channel in the exhaust section; a first microwave suppression sleeve is attached to the inner wall of the exhaust section close to the discharging section, and a second microwave suppression sleeve is attached to the inner wall of the discharging section below the outlet of the conveying pipe.

[0018] According to an example of the present invention, a circulating water cooling jacket structure is provided on the outer wall of the microwave suppression tube, and a circulating water cooling plate structure is attached and fixed to the outer wall of the high-power microwave receiving cavity.

[0019] According to an example of the present invention, a microwave generator is installed at the microwave inlet of the high-power microwave receiving cavity, and the microwave generator is separated from the high-power microwave receiving cavity by a quartz plate.

[0020] According to an example of the present invention, it also includes a safety alarm module for detecting microwave leakage, and the safety alarm module includes multiple microwave leakage detection probes respectively installed at the feed end of the conveying pipe, the exhaust outlet end of the exhaust section, and the discharge outlet end of the discharge section.

[0021] Compared with the prior art, the technical solution of the utility model has the following advantages:

[0022] (1) The system for continuously and efficiently preparing two-dimensional carbon materials by microwave method disclosed in the present application improves the conventional pneumatic conveying feeding structure, adopts the method of arranging the microwave device body and the internal feeding pipe in an inclined manner, and cooperates with the rotating unit to drive the feeding pipe to rotate at a uniform speed, thereby realizing continuous, stable and uniform feeding operation in the microwave preparation process without staying in the microwave expansion zone, optimizing the reaction environment of the graphite material in the high-power microwave receiving cavity to improve the quality of the finished products of two-dimensional carbon materials such as graphene and improve the preparation efficiency.

[0023] (2) The system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method disclosed in this application preferably has a variable diameter tubular structure in which the discharge end gradually expands relative to the feed end. Compared with conventional preparation devices, this system does not cause material blockage and can reduce the size of the equipment, making the overall device more compact, precise, and lightweight.

[0024] (3) The system for continuously and efficiently preparing two-dimensional carbon materials using the microwave method disclosed in this application has a multi-point suppression structure including a microwave suppression tube, a microwave suppression grid, and a microwave suppression bushing in the entire process of microwave preparation. The device as a whole has extremely strong anti-microwave leakage characteristics.

[0025] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 It is a flow chart of the graphene preparation process in the embodiment of the present utility model.

[0028] Figure 2 This is a simplified diagram of the graphene preparation process device layout and process flow in the embodiment of the present utility model.

[0029] Figure 3 This is an overall structural diagram of a carbon material continuous and efficient microwave preparation system in an embodiment of the present utility model.

[0030] Figure 4 It is a longitudinal cross-sectional view of a system for continuously and efficiently preparing carbon materials using microwave method in an embodiment of the present utility model.

[0031] Figure 5 yes Figure 4 A magnified structure diagram of part A.

[0032] Figure 6 yes Figure 4 Enlarged structure diagram of part B.

[0033] Figure 7 yes Figure 4 Enlarged structure diagram of part C.

[0034] Figure 8 It is a structural diagram of a variable diameter material conveying pipe in an embodiment of the present utility model.

[0035] Figure 9 It is a cross-sectional view of the high-power microwave unit along the radial direction of the feed pipe in an embodiment of the present utility model.

[0036] Figure 10 This is the Raman spectrum obtained in Example 2 of this application.

[0037] Figure 11 This is the transmission electron microscope image 1 obtained in Example 2 of the present application, where the scale is 5 nm.

[0038] Among them, the accompanying drawings are marked as: 1. Microwave suppression tube, 2. High-power microwave unit, 201. High-power microwave receiving cavity, 3. Discharge section, 4. Receiving bin, 5. Exhaust section, 6. Feed pipe, 7. Reflection focusing plate, 8. Microwave generator, 9. Support frame, 10. Infrared temperature measurement module, 11. Screen, 12. Microwave suppression grid, 13. First microwave suppression bushing, 14. Second microwave suppression bushing, 15. Circulating water cooling jacket structure, 16. Circulating water cooling plate structure, 17. Quartz plate, X, high microwave power zone. DETAILED DESCRIPTION

[0039] The following describes in detail embodiments of the present invention, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0040] This application takes the preparation of graphene products as an example, and the analysis method in the embodiment is as follows:

[0041] Graphene was analyzed using Raman spectroscopy and the 200~3250cm -1 The spectrum within the range is fitted and I is obtained. D / I G Value, I 2D / I G Value, judge the graphene defects and layer number;

[0042] Graphene was analyzed using a transmission electron microscope to determine the number of graphene layers.

[0043] In this application, the preparation method of the graphene product (for example, but not limitation, the preparation system can also be applied to other carbon materials, such as the preparation of two-dimensional or three-dimensional carbon materials such as graphite oxide and expanded graphite) includes:

[0044] (1) Graphite intercalation modification technology, namely the formulation of intercalation agents and graphite pretreatment process;

[0045] (2) Microwave reaction system technology, including automatic loading module, inclined feed pipe rotation and continuous expansion technology, reaction chamber temperature measurement module, unloading module and exhaust gas absorption module;

[0046] According to one embodiment of the present application, the graphene preparation process flow chart is as follows: Figure 1 As shown, the following steps are included:

[0047] Pretreatment: Graphite A is soaked in an intercalating agent to form a graphite A solution;

[0048] Filtration and drying: Graphite A solution is subjected to solid-liquid separation, and the graphite surface is dried to remove the residual liquid to obtain graphite B;

[0049] Microwave feeding: Materials are transported to the microwave equipment by tilting the feed pipe and continuously rotating it. The processed graphite B reaches the microwave zone under the action of the rotation of the tilted feed pipe, completes physical expansion in a short period of time, and forms graphene A; it continues to move forward under the action of the rotation of the tilted feed pipe and falls into the receiving bin.

[0050] Example 1

[0051] See also Figures 3 to 9 As shown, this embodiment provides a system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method, comprising a microwave suppression tube 1 and a high-power microwave unit 2, which are arranged obliquely and connected to each other; wherein, the end of the high-power microwave unit 2 away from the microwave suppression tube 1 is connected to a discharge section 3, the bottom of the discharge section 3 is connected to a receiving bin 4, and the top of the discharge section 3 is connected to an exhaust section 5;

[0052] The high-power microwave unit 2 is provided with a high-power microwave receiving cavity 201, within which a microwave expansion zone is provided. The device further comprises a feed pipe 6, a rotating unit, and an exhaust gas treatment unit. The feed pipe 6 is arranged at an angle and sequentially passes through the microwave suppression tube 1 and the microwave expansion zone before extending to the discharge section 3. The feed pipe 6 is mounted on the rotating unit and can be driven by the rotating unit to rotate along the axis of the feed pipe 6. The exhaust end of the exhaust section 5 is connected to the exhaust gas treatment unit. The rotating unit may include a rotating motor and a transmission member, such as a gear transmission component. The output shaft of the rotating motor is connected to the feed pipe via the transmission member. For example, the feed end of the feed pipe is partially extended out of the microwave suppression tube, and an external gear member is engaged with the transmission member. When the rotating motor is in operation, the feed pipe is driven to rotate at a constant speed. When the system is in operation, the low-speed rotation speed of the feed pipe is adjustable, and can be designed to rotate clockwise or counterclockwise according to actual operating conditions. The exhaust gas treatment unit may include a negative pressure blower connected to the exhaust port of the exhaust section via a pipeline, thereby removing the waste gas generated during the graphene preparation process through negative pressure suction. In this application, the device is not limited to the preparation of graphene products. Graphite products involving intercalation agents can be expanded by microwaves. The device is particularly suitable for the preparation of two-dimensional or three-dimensional carbon materials such as graphene oxide and expanded graphite. The feed pipe 6 may be made of a quartz tube or a ceramic tube.

[0053] Preferably, in this application, the high-power microwave unit 2 utilizes a microwave generator 8 with a frequency of 915 MHz or 2450 MHz, and a power of 1 kW to 100 kW. After the system is activated, the feed pipe 6 begins to slowly rotate and continuously feeds expandable material. The material rapidly passes through the microwave expansion zone and absorbs the microwaves, creating a high-temperature environment. In this embodiment, based on the design and use of a high-power microwave unit, when the microwave generator 8 is raised to a high-power, stable operating state, the material in the feed pipe 6 can form a localized high-temperature environment of 300° to 1000° within 0 to 2 seconds as it passes through the microwave expansion zone.

[0054] As a supporting device, an automatic loader should also be connected to the front end feeding part of the conveying pipe 6. The automatic loader is a feeding device composed of at least one of a vibration feeder, a weight feeder, a volume auger feeder, a syringe, a compressed air assisted feeder, a vacuum assisted feeder, a gravity feeder, a drum feeder, a wheel feeder, a slide rail, a chute, and a conveyor feeder.

[0055] As one improved form, the portion of the feed pipe 6 located within the microwave expansion zone is an expansion section. This expansion section is a variable-diameter tubular structure, with its diameter gradually increasing from the feed side toward the discharge side. This gradually increasing diameter makes this design less susceptible to blockage compared to conventional medium-diameter feed pipes in preparation equipment. While constant-diameter feed pipes often result in oversized preparation equipment, the variable-diameter feed pipe, adapted to the expansion behavior of the graphite material, reduces the size and structural complexity of the device's external accessories, resulting in a more compact, precise, and lightweight device.

[0056] like Figure 9 As shown, the feed pipe 6 of the present application is mainly composed of two parts: a small-diameter feed end front section and a large-diameter expansion pipe section. The feed end uses a small-diameter feed pipe. ① From the perspective of feed quantity and material volume, the small-diameter feed pipe can fully meet the feed space requirements of graphite powder before expansion; ② microwaves will leak at the opening of the feed end of the high-power microwave receiving cavity. In order to prevent leakage, a suppression tube or a suppressor with absorbing ability will be installed at the opening. The small-diameter feed pipe can use shorter or fewer suppression tubes and suppressors in terms of length and dosage to suppress microwave leakage, reducing the overall size and cost of the device; ③ the entire equipment will save floor space. The middle section of the microwave irradiation part and the tail section of the discharge end of the feed pipe 6 use large-diameter feed pipes. Considering that the processed graphite expands in volume when encountering microwaves, in order to prevent the expanded material from clogging the feed pipe, sufficient space needs to be reserved. The cross-sectional area after expansion is less than or equal to 80% of the cross-sectional area inside the feed pipe.

[0057] Preferably, the inclination angle of the feed pipe 6 relative to the horizontal plane is 5°~80°. In this embodiment, the feed pipe 6 is designed to have an inclination angle of 30° relative to the horizontal plane, maintaining a relatively obvious and reasonable inclination angle as a whole, which can ensure that the material in the feed pipe 6 has a stable and smooth feeding effect.

[0058] According to an example of the present invention, Figure 6 As shown, a reflective focusing plate 7 is provided at the bottom corner of the high-power microwave receiving cavity 201. The reflective focusing plate is arranged toward the material conveying pipe 6 in the high-power microwave receiving cavity 201 to drive the microwave energy to concentrate toward the center of the high-power microwave receiving cavity 201 and form a high microwave power area X in the local space ( Figure 8 The dotted elliptical area shown in the figure continuously covers the lower area of ​​the feed pipe 6, resulting in a very high microwave energy density in this area. The energy utilization rate of the concentrated energy in this area can reach 80%-95% of the output power of the microwave generator 8. In this embodiment, a reflective focusing plate 7 is provided at the left and right bottom corners of the bottom of the high-power microwave receiving cavity 201. These reflective focusing plates 7 are arranged on the upper and lower sides of the high-power microwave receiving cavity 201 opposite to the microwave generator 8 to focus microwave irradiation and reduce energy loss. The reflective focusing plate 7 can be an accessory installed in the high-power microwave receiving cavity 201, or it can be an oblique bottom corner plate at the bottom of the high-power microwave receiving cavity 201. In this design, the high-power microwave receiving cavity 201 is formed as an integral steel plate stamping.

[0059] According to an example of the present invention, a number of support frames 9 are provided on the inner wall of the high-power microwave receiving cavity 201, and the feed pipe 6 is mounted and fixed on the support frames 9 to provide stable support for the middle part of the overall longer feed pipe 6 to prevent the feed pipe 6 from vibrating significantly during rotation.

[0060] According to one example of the present invention, a high-power microwave receiving cavity 201 is equipped with an infrared temperature measurement module 10 for monitoring the temperature within the microwave expansion zone. This module is used to monitor the reaction temperature of the intercalated modified graphite sample under microwave irradiation, thereby facilitating process stability monitoring. The infrared temperature measurement module 10 can utilize a temperature probe and is linked to the control of the microwave generator 8. This module feeds back the real-time operating temperature parameters within the high-power microwave receiving cavity 201 to the microwave generator 8. When the real-time temperature in the microwave expansion zone exceeds a preset threshold, the microwave generator 8 adjusts its power or automatically shuts down, providing temperature protection for the device.

[0061] According to an example of the present invention, a screen 11 is installed in one end of the exhaust section 5 close to the discharge section 3. The screen 11 can be a polytetrafluoroethylene screen, which is used to intercept the powder floating upward from the discharge port end of the conveying pipe 6. A microwave suppression grid 12 is installed between the screen 11 and the exhaust section. The microwave suppression grid 12 has a number of grid plates arranged vertically and horizontally. The gaps between the grid plates extend in the same direction as the exhaust channel in the exhaust section, and have a good effect of suppressing microwave leakage.

[0062] Most graphene production processes involve more or less strong acidic chemicals. The aforementioned screen 11 can be prepared by: polytetrafluoroethylene (PTFE) and some modified plastics derived from it, polyvinylidene fluoride (PVDF) and some modified plastics derived from it, polyvinyl chloride (PVC) and some modified plastics derived from it, polypropylene (PP) and some modified plastics derived from it, soluble polytetrafluoroethylene (PFA) and some modified plastics derived from it coated with metal wire, etc.

[0063] The microwave suppression tube 1 and the microwave suppression grid 12 can be made of steel. The suppression ability of the steel tube mainly depends on the cross-sectional area and length; the microwave suppression ability of the grid mainly depends on the grid density and spatial height (the energy density of the microwave itself will be suppressed due to the small leakage window during spatial propagation, and will also attenuate as the distance increases). The microwave suppression grid 12 of the present application has densely crossed grid plates and has excellent microwave suppression ability.

[0064] According to an example of the present invention, a first microwave suppression sleeve 13 is attached to the inner wall of the exhaust section 5 at one end close to the discharge section 3, and a second microwave suppression sleeve 14 is attached to the inner wall of the discharge section below the outlet of the conveying pipe.

[0065] In the present application, the first microwave suppression bushing 13 and the second microwave suppression bushing 14 are both composed of four suppression plates forming a square frame structure, which assist in enhancing microwave suppression in the exhaust section 5 and the discharge section 3 respectively. The two microwave suppression bushings are made of silicon carbide material plates, which assist in absorbing microwaves when the window of the high-power microwave receiving cavity is large and the reserved suppression grid length is insufficient.

[0066] According to one embodiment of the present invention, a circulating water-cooling jacket structure 15 is provided on the outer wall of the microwave suppression tube 1, and a circulating water-cooling plate structure 16 is attached to the outer wall of the high-power microwave receiving cavity 201. The core temperature in the center of the microwave expansion zone is relatively high, requiring continuous cooling to achieve an ideal reaction environment. In this embodiment, a bottom-inlet, top-outlet circulating water-cooling structure is added to the front and rear sides of the high-power microwave receiving cavity 201, as well as to the exterior of the microwave suppression tube 1 at the feed front. As one feasible design, the microwave suppression tube 1 and the circulating water-cooling jacket structure 15 can be integrated into a single piece.

[0067] According to an example of the present invention, a microwave generator 8 is installed at the microwave entrance of the high-power microwave receiving cavity. The microwave generator and the high-power microwave receiving cavity are separated by a quartz plate 17 to prevent absorbing materials from entering the waveguide upward and causing pollution to the microwave source.

[0068] According to one example of the present invention, the system also includes a safety alarm module for detecting microwave leakage. This module is communicatively connected to the system's master control. The safety alarm module includes multiple microwave leakage detection probes installed at the feed end of the conveyor pipe, the exhaust outlet of the exhaust section, and the discharge outlet of the discharge section. These probes monitor microwave radiation levels at each window in real time. If microwave radiation in a corresponding area exceeds a safety threshold, the system's master control generates a safety alarm and shuts down the microwave generator.

[0069] Example 2

[0070] Using the continuous and efficient preparation system in the embodiment of this application, according to Figure 1 、 Figure 2 The specific steps for preparing graphene are as follows:

[0071] 1. Preparation of intercalated graphite:

[0072] (1) Prepare dispersant and select 97 ml of water as dispersant;

[0073] (2) Prepare the intercalant solution by adding 3 ml of bromine intercalant to the dispersant to achieve a volume concentration of 3%;

[0074] (3) Using the intercalation agent solution obtained above, the graphite was pre-treated by soaking. The graphite was natural flake graphite with a particle size of 50 mesh; the volume ratio of the intercalation agent solution to the graphite was 1:6. The graphite was soaked in the intercalation agent solution for 6 hours, and then sealed and stored for 12 hours. Stirring was performed at the same time, and the stirring speed was 20 rpm. After stirring, a graphite A solution was obtained. The above-mentioned graphite A solution was filtered and air-dried to obtain intercalation-modified graphite B. The solid content of the intercalation-modified graphite B was 80%.

[0075] 2. Preparation of fluffy graphene:

[0076] The intercalated and modified graphite B was fed to the feed end of a feed pipe via an automatic feeder (loss-in-weight feeder). The rotating unit was activated to continuously rotate the feed pipe, conveying the graphite B to the microwave expansion zone. After instantaneous high-power irradiation in the microwave expansion zone, the graphite B expanded under its own weight and the rotation of the feed pipe. The microwave equipment had a power of 10 kW, a feed rate of 45 g / min, and a reaction temperature of 350°C.

[0077] The volume of graphene was measured using a graduated cylinder, and it was calculated that the expansion ratio of the graphene product obtained in step 2 was 99 times that of the raw graphite.

[0078] The number of layers of graphene products measured by transmission electron microscopy is 3 to 5. Figure 11 shown.

[0079] Characterized by Raman spectroscopy, such as Figure 10 As shown in the figure, the Raman fitting results also verify that the number of graphene layers is 3 to 5.

[0080] The intensity ratio of the D peak to the G peak of graphene (I D / I G ) is 0.012.

[0081] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; they can refer to direct connection or indirect connection through an intermediate medium; they can refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0082] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are illustrative and cannot be understood as limitations on the present invention. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present invention.

[0083] Various changes and modifications will undoubtedly become apparent to those skilled in the art after reading the above description. Therefore, the appended claims should be construed to encompass all changes and modifications within the true intent and scope of the present invention. Any and all equivalents within the scope of the claims should be considered to be within the intent and scope of the present invention.

Claims

1. A system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method, characterized in that: The invention comprises a microwave suppression tube and a high-power microwave unit which are arranged obliquely and connected. The end of the high-power microwave unit away from the microwave suppression tube is connected to a discharge section, the bottom of the discharge section is connected to a receiving bin, and the top of the discharge section is connected to an exhaust section. The high-power microwave unit is provided with a high-power microwave receiving cavity, and a microwave expansion zone is provided in the high-power microwave receiving cavity. The system also includes a feed pipe, a rotating unit and an exhaust gas treatment unit. The feed pipe is arranged at an angle and passes through the microwave suppression tube and the microwave expansion zone in sequence and then extends to the discharge section. The feed pipe is loaded on the rotating unit and can be driven by the rotating unit to rotate along the axis of the feed pipe. The exhaust end of the exhaust section is connected to the exhaust gas treatment unit.

2. The system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method according to claim 1, characterized in that: The portion of the feed pipe located inside the microwave expansion zone is an expansion pipe section, and the expansion pipe section is a variable diameter tubular structure with a diameter gradually increasing from the feed side toward the discharge side.

3. A system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method according to claim 1 or 2, characterized in that: The inclination angle of the conveying pipe relative to the horizontal plane is 5°~80°.

4. The system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method according to claim 1, characterized in that: A reflective focusing plate is provided at the bottom corner of the high-power microwave receiving cavity. The reflective focusing plate is arranged toward the feed pipe in the high-power microwave receiving cavity to drive the microwave energy to concentrate toward the center of the high-power microwave receiving cavity and form a high microwave power area in a local narrow space.

5. The system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method according to claim 1, characterized in that: The high-power microwave unit includes a microwave generator with a frequency of 915 MHz or 2450 MHz, and the power of the microwave generator is 1 kW to 100 kW; When the microwave generator is in steady-state operation, the material in the conveying pipe can form a local high-temperature environment of 300°C to 1000°C within 0-2S when passing through the microwave expansion zone.

6. The system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method according to claim 1, characterized in that: The high-power microwave receiving cavity is provided with an infrared temperature measurement module for monitoring the temperature in the microwave expansion zone.

7. The system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method according to claim 1, characterized in that: A screen is installed in one end of the exhaust section close to the discharge section, and a microwave suppression grid is installed between the screen and the exhaust section. The microwave suppression grid has a plurality of grid plates arranged vertically and horizontally, and the gaps between the grid plates extend in the same direction as the exhaust channel in the exhaust section; A first microwave suppression bushing is attached to the inner wall of the exhaust section at one end close to the discharge section, and a second microwave suppression bushing is attached to the inner wall of the discharge section below the outlet of the conveying pipe.

8. The system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method according to claim 1, characterized in that: A circulating water cooling jacket structure is provided on the outer wall of the microwave suppression tube, and a circulating water cooling plate structure is attached and fixed on the outer wall of the high-power microwave receiving cavity.

9. The system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method according to claim 5, characterized in that: A microwave generator is installed at the microwave entrance of the high-power microwave receiving cavity, and the microwave generator and the high-power microwave receiving cavity are separated by a quartz plate.

10. The system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method according to claim 1, characterized in that: It also includes a safety alarm module for detecting microwave leakage, which includes multiple microwave leakage detection probes respectively installed at the feed end of the conveying pipe, the exhaust outlet end of the exhaust section, and the discharge outlet end of the discharge section.

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