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

Abstract

The invention 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 present invention 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 for short), etc.

[0003] Graphene is a two-dimensional carbon material composed of carbon atoms in a hexagonal honeycomb lattice with sp² hybrid orbitals. It has excellent optical, electrical, mechanical and thermal properties, and can be widely used in battery electrode materials, semiconductor devices, transparent display screens, sensors, capacitors, transistors, etc. In view of the excellent performance of graphene materials and their potential application value, a series of important progress has been made in many disciplines such as chemistry, materials, physics, biology, environment, and energy.

[0004] The mainstream graphene preparation methods include graphite oxide reduction method (Hummers method) and chemical vapor deposition method (CVD method). The Hummers method is to first oxidize graphite into graphite oxide with strong oxidants such as concentrated sulfuric acid, concentrated nitric acid, potassium permanganate, etc., and then peel it into graphene oxide through ultrasonic treatment, and then dialysis purification and reduction to obtain graphene powder. The Hummers method has a long process cycle and serious pollution, and the obtained graphene has many defects and poor quality, which limits its application in high-end scenarios. The graphene prepared by the CVD method is of high quality, but it has the disadvantages of complex process and high cost, which makes it difficult to apply it on a large scale in industry.

[0005] Microwave exfoliation of graphene refers to the preparation of graphene by exfoliating graphite sheets using the huge energy released by the gasification effect of microwaves. This preparation method has the advantages of being efficient and green, and shows great potential in the field of large-scale rapid preparation of graphene.

[0006] Graphene oxide (Graphene Oxide), graphene oxide is a layered graphite oxide, composed of isolated single-molecule graphite layers, with certain gaps between layers, which makes it have a large specific surface area and provides abundant reaction sites for various physical and chemical processes. It has excellent physical, chemical, optical and electrical properties, and because there are multiple oxygen-containing functional groups coexisting on the basal plane and edge of the graphene sheet skeleton, graphene oxide can modulate its conductivity and band gap by regulating the type and amount of oxygen-containing functional groups contained. The material has a wide range of applications. Graphene oxide is a new type of carbon material with excellent performance, with a high specific surface area and rich functional groups on the surface. Graphene oxide composite materials, including polymer composite materials and inorganic composite materials, have a wide range of applications.

[0007] Early methods for preparing graphene oxide were mainly chemical oxidation methods such as the Brodie method, the Staudenmaier method and the Hummers method. The Brodie method is the earliest reported method for preparing graphene oxide. It uses fuming nitric acid and potassium chlorate to oxidize graphite, but this method has a violent reaction, is prone to explosion hazards and has a large pollution to the environment. The Staudenmaier method is an improvement on the Brodie method. It uses a mixed acid of concentrated sulfuric acid and fuming nitric acid and potassium chlorate to oxidize graphite, which improves the degree of oxidation to a certain extent, but there are still safety and environmental issues. The Hummers method uses concentrated sulfuric acid, sodium nitrate and potassium permanganate as oxidants, which is relatively safer and milder. It has become one of the most commonly used methods for preparing graphene oxide, but the oxidants used in this method still cause great pollution to the environment.

[0008] Microwave exfoliation of graphene oxide refers to the use of the huge energy released by the gasification effect of microwaves to exfoliate graphene oxide sheets to prepare graphene oxide. This preparation method has the advantages of high efficiency, greenness, selective heating, and easy functional modification, and shows great potential in the field of large-scale rapid preparation of graphene.

[0009] Expanded graphite (EG) is obtained by intercalation and expansion of natural flake graphite. From a microscopic perspective, it has a worm-like morphology. Its basic structural unit is graphite flakes, which are stretched out along the interlayer direction under the action of the gas produced by the thermal decomposition of the intercalated material. In three-dimensional space, numerous graphite flakes are interlaced and superimposed to form a large number of irregular pores. These pores are of different sizes and interconnected, giving expanded graphite a loose and porous characteristic, giving it a large specific surface area, which can play an advantage in many application scenarios such as adsorption and filtration.

[0010] In the existing microwave carbon material production process, there is still a lot of 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 materials in the microwave reactor and affects the quality of graphite-related products (the degree of expansion and thermal stripping). The design for suppressing microwave leakage also needs to be strengthened. Summary of the invention

[0011] The object of the present invention 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 to each other; 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 gas treatment unit.

[0012] According to an example of the present invention, the position of the feed conveying pipe located inside the microwave expansion zone is an expansion pipe section, and the expansion pipe section is a variable diameter tubular structure whose diameter gradually increases 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 zone 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~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°~1000° within 0~2S 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 to monitor 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, a microwave suppression grid is installed between the screen and the exhaust section, the microwave suppression grid has a plurality of grid plates vertically and horizontally arranged, 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 one end 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 entrance 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 a plurality of 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 present invention has the following advantages: (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 tilting the microwave device body and the internal feeding pipe, and cooperates with the rotating unit to drive the feeding pipe to rotate at a uniform speed. It can realize continuous, stable and uniform feeding operation in the microwave preparation process without staying in the microwave expansion zone, optimizes the reaction environment of the graphite material in the high-power microwave receiving cavity to improve the finished product quality of two-dimensional carbon materials such as graphene, and improves the preparation efficiency.

[0022] (2) In the system for continuously and efficiently preparing two-dimensional carbon materials using a microwave method disclosed in the present application, the feed pipe is preferably a variable diameter tubular structure, and the discharge end gradually expands relative to the feed end. Compared with conventional preparation devices, it does not cause material blockage and can reduce the size of the equipment, making the overall device more compact, precise, and lightweight.

[0023] (3) The system for continuously and efficiently preparing two-dimensional carbon materials by microwave method disclosed in the present application has a suppression structure with a multi-point layout including a matching 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.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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 creative work.

[0026] Figure 1 It is a flowchart of the graphene preparation process in an embodiment of the present invention.

[0027] Figure 2 It is a schematic diagram of the layout of the graphene preparation process equipment and the process flow in an embodiment of the present invention.

[0028] Figure 3 It is an overall structural diagram of a system for continuous and efficient preparation of carbon materials by microwave method in an embodiment of the present invention.

[0029] Figure 4 It is a longitudinal cross-sectional view of a system for continuous and efficient preparation of carbon materials using microwave method in an embodiment of the present invention.

[0030] Figure 5 yes Figure 4 A-part enlarged structure diagram.

[0031] Figure 6 yes Figure 4 Enlarged structure diagram of part B.

[0032] Figure 7 yes Figure 4 Enlarged structure diagram of part C.

[0033] Figure 8 It is a structural diagram of a variable diameter material conveying pipe in an embodiment of the present invention.

[0034] Fig. 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 invention.

[0035] Fig.10 This is the Raman spectrum obtained in Example 2 of the present application.

[0036] Fig.11 This is the transmission electron microscopy image I obtained in Example 2 of the present application, where the scale is 5 nm.

[0037] 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. conveying pipe, 7. reflection focusing plate, 8. microwave generator, 9. support frame, 10. infrared temperature measurement module, 11. sieve, 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 area. DETAILED DESCRIPTION

[0038] Embodiments of the present invention are described in detail below, 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 be used to explain the present invention, and should not be construed as limiting the present invention.

[0039] This application takes the preparation of graphene products as an example, and the analysis method in the embodiment is as follows: Graphene was analyzed using Raman spectroscopy and the 200~3250cm -1 The spectrum in the range is fitted and I is obtained. D / I G Value, I 2D / I G Value, determine the graphene defects and number of layers; Graphene was analyzed using a transmission electron microscope to determine the number of graphene layers.

[0040] In the present application, the preparation method of the graphene product (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: (1) Graphite intercalation modification technology, i.e. the formulation of intercalation agent and graphite pretreatment process; (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 waste gas absorption module; 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: Pretreatment: soaking graphite A with an intercalating agent to form a graphite A solution; Filtration and drying: separate the solid and liquid of the graphite A solution, then dry the graphite surface to remove the residual liquid to obtain graphite B; 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 rotation of the tilted feed pipe, completes physical expansion in a short period of time, and forms graphene A; it continues to move forward and falls into the receiving bin under the rotation of the tilted feed pipe.

[0041] Example 1 See also Figures 3~9 As shown, this embodiment provides a system for continuously and efficiently preparing two-dimensional carbon materials by microwave method, including a microwave suppression tube 1 and a high-power microwave unit 2 which are arranged obliquely and connected; 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; the high-power microwave unit 2 is provided with a high-power microwave receiving cavity 201, and a microwave expansion zone is provided in the high-power microwave receiving cavity 201; the device also includes a feed pipe 6, a rotating unit and an exhaust gas treatment unit, the feed pipe 6 is arranged obliquely and passes through the microwave suppression tube 1 and the microwave expansion zone in sequence and then extends to the discharge section 3, the feed pipe 6 is loaded on the rotating unit and can be driven by the rotating unit to rotate along the axis of the feed pipe 6, and the exhaust end of the exhaust section 5 is connected to the exhaust gas treatment unit. Wherein, the rotating unit may include a rotating motor and a transmission member, such as a gear transmission member, and the output shaft of the rotating motor is connected to the feed pipe through the transmission member, for example, the feed end of the feed pipe is partially extended out of the microwave suppression tube, and the external gear member is meshed with the transmission member, and the feed pipe is driven to rotate at a uniform speed when the rotating motor is in working state. When the system is running, the low-speed rotation speed of the feed pipe is adjustable, and the clockwise or counterclockwise rotation can be designed according to the actual working conditions. Wherein, the tail gas treatment unit may include a negative pressure fan, which is connected to the exhaust port of the exhaust section through a pipeline, and the waste gas generated in the graphene preparation process is sucked away by the negative pressure suction effect. In the present application, the device is not limited to the preparation of graphene products, and graphite products involving intercalation agents can be expanded by microwave method. The device is also particularly suitable for the preparation of two-dimensional or three-dimensional carbon materials such as graphene oxide and expanded graphite, wherein the feed pipe 6 can be made of pipes such as quartz tubes or ceramic tubes.

[0042] Preferably, in the present application, the high-power microwave unit 2 uses a microwave generator 8 with a frequency of 915MHz or 2450MHz, and the power of the microwave generator 8 is 1KW~100KW. After the system is turned on, the feed pipe 6 starts to rotate slowly and continuously feeds the expandable material. The material quickly passes through and absorbs microwaves in the microwave expansion zone to form a high-temperature environment. In this embodiment, under the premise of designing and using a high-power microwave unit, when the microwave generator 8 is upgraded to a high-power stable operation state, the material in the feed pipe 6 can form a local high-temperature environment of 300°~1000° within 0~2S when passing through the microwave expansion zone.

[0043] As a supporting device, an automatic loader should also be connected to the front end feeding part of the feed pipe 6. The automatic loader is a feeding device composed of at least one of a vibration feeder, a gravimetric 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.

[0044] As one of the improved forms, the part of the feed pipe 6 located in the microwave expansion zone is an expansion pipe section, and the expansion pipe section is a variable diameter tubular structure whose diameter gradually increases from the feed side to the discharge side. The diameter of the expansion pipe section of the feed pipe 6 gradually increases. Compared with the medium diameter feed pipe structure of the conventional preparation device, this design is not easy to block the material. The equal diameter feed pipe causes the size of the adapted preparation equipment to be too large. The variable diameter feed pipe matches the expansion law of the graphite material, which can reduce the size and structural complexity of the external accessories of the device, making the device more compact, precise and lightweight as a whole.

[0045] like Fig. 9 As shown, the feed pipe 6 of the present application is mainly composed of a front section of a small-diameter feed end and a large-diameter expansion pipe section. Among them, a small-sized feed pipe is used at the feed end. ① From the perspective of feed amount and material volume, the small-sized feed pipe can fully meet the demand for feed space 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 wave absorbing ability will be installed at the opening. A small-diameter feed pipe can use shorter or fewer suppression tubes and suppressors in length and dosage to suppress microwave leakage, thereby reducing the overall size and cost of the device; ③ the overall equipment will save floor space. A large-diameter feed pipe is used for the middle section microwave irradiation part and the tail section discharge end of the feed pipe 6. 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, and the cross-sectional area after expansion is less than or equal to 80% of the cross-sectional area inside the feed pipe.

[0046] 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.

[0047] 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, and the reflective focusing plate is arranged toward the material conveying pipe 6 in the high-power microwave receiving cavity 201, so as 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 8The dotted ellipse area shown in the figure continuously covers the bottom side area of ​​the feeding pipe 6, so that the microwave energy density in this area is extremely large, and 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 respectively provided at the left and right bottom corners of the bottom of the high-power microwave receiving cavity 201, and is arranged on the upper and lower sides of the high-power microwave receiving cavity 201 opposite to the microwave generator 8, for focusing microwave irradiation and reducing energy loss. Among them, 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 of the bottom of the high-power microwave receiving cavity 201. In this design, the high-power microwave receiving cavity 201 is an integrally formed steel plate stamping part.

[0048] According to an example of the present invention, a plurality 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.

[0049] According to an example of the present invention, an infrared temperature measurement module 10 is provided on the high-power microwave receiving cavity 201 to monitor the temperature in the microwave expansion zone. It is used to monitor the reaction temperature of the intercalated modified graphite sample under microwave irradiation, so as to monitor the stability of the process. The infrared temperature measurement module 10 can use a temperature measurement probe, and is linked with the control of the microwave generator 8 to feed back the real-time sensed working temperature parameters in the high-power microwave receiving cavity 201 to the microwave generator 8. When the real-time temperature in the microwave expansion zone exceeds the preset threshold, the microwave generator 8 controls the power adjustment or automatically shuts down to perform temperature control protection on the equipment.

[0050] 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 may be a polytetrafluoroethylene screen for intercepting powder floating upward from the discharge port end of the feed pipe 6. A microwave suppression grid 12 is installed between the screen 11 and the exhaust section. The microwave suppression grid 12 has a plurality 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.

[0051] Most graphene production processes involve more or less strong acidic chemicals. The aforementioned screen 11 can be prepared by selecting: 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.

[0052] 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 the propagation of the space, and will also attenuate with the increase of the distance). The microwave suppression grid 12 of the present application has densely crossed grid plates and has excellent microwave suppression ability.

[0053] According to an example of the present invention, a first microwave suppression bushing 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 bushing 14 is attached to the inner wall of the discharge section below the outlet of the conveying pipe.

[0054] 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.

[0055] According to an example 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 and fixed on the outer wall of the high-power microwave receiving cavity 201. The core temperature focused in the central part of the microwave expansion zone is relatively high, and continuous cooling treatment is required to obtain an ideal reaction environment. In this embodiment, a bottom-in-and-top-out circulating water cooling structure is added to the front and rear sides of the high-power microwave receiving cavity 201 and the front end of the microwave suppression tube 1 at the feed. As one of the feasible designs, the microwave suppression tube 1 can be integrated with the circulating water cooling jacket structure 15 in an integrated design.

[0056] 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, and the microwave generator is separated from the high-power microwave receiving cavity by a quartz plate 17 to prevent absorbing materials from entering the waveguide upward and polluting the microwave source.

[0057] According to an example of the present invention, the system further includes a safety alarm module for detecting microwave leakage, which is connected to the system master control for communication. The safety alarm module includes a plurality of 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, for real-time detection of microwave radiation levels at each window. When it is detected that the microwave radiation in the corresponding area exceeds the safety threshold, the system master control issues a safety alarm and controls the microwave generator to shut down.

[0058] Example 2 Using the continuous and efficient preparation system in the embodiment of the present application, according to Figure 1 , Figure 2The specific steps of preparing graphene are as follows: 1. Preparation of intercalated graphite: (1) Prepare the dispersant and select 97 ml of water as the dispersant; (2) Prepare the intercalant solution by adding 3 ml of bromine intercalant to the dispersant at a volume concentration of 3%; (3) Use the intercalation agent solution obtained above to pre-treat graphite by soaking. The graphite is natural flake graphite with a particle size of 50 mesh; the volume ratio of the intercalation agent solution to the graphite is 1:6. Soak the graphite in the intercalation agent solution for 6 hours, and then seal and store for 12 hours. Stir at the same time, and the stirring speed is 20 rpm. After stirring, a graphite A solution is obtained. The above-mentioned graphite A solution is filtered and air-dried to obtain intercalation-modified graphite B. Among them, the solid content of the intercalation-modified graphite B is 80%.

[0059] 2. Preparation of fluffy graphene: The intercalated modified graphite B is pushed to the feeding end of the feeding pipe through an automatic feeder (weightless feeder). The rotating unit is turned on to continuously rotate the feeding pipe to transport graphite B to the microwave expansion zone. After the graphite B is expanded by instantaneous high-power irradiation in the microwave expansion zone, it moves forward under the action of its own weight and the rotation of the feeding pipe. The power of the microwave equipment is 10kW, the feeding speed of graphite B is 45g / min, and the reaction temperature of the microwave equipment is 350℃.

[0060] The volume of graphene was measured using a measuring 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.

[0061] The number of layers of graphene products measured by transmission electron microscopy is 3 to 5. Fig.11 shown.

[0062] Characterized by Raman spectroscopy, such as Fig.10 As shown, the Raman fitting results also verify that the number of graphene product layers is 3 to 5.

[0063] The intensity ratio of the D peak to the G peak of graphene (I D / I G ) is 0.012.

[0064] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

[0066] For those skilled in the art, various changes and modifications will undoubtedly be obvious after reading the above description. Therefore, the attached claims should be regarded as covering all changes and modifications of the true intent and scope of the present invention. Any and all equivalent ranges and contents within the scope of the claims should be considered to still be within the intent and scope of the present invention.

Claims

1. A system for continuously and efficiently preparing two-dimensional carbon materials by microwave method, characterized in that: It 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 discharging section, the bottom of the discharging section is connected to a receiving bin, and the top of the discharging 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. 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 by microwave method according to claim 1, characterized in that: The position of the feed conveying 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, 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.

5. The system for continuously and efficiently preparing two-dimensional carbon materials by 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 feed pipe can form a local high temperature environment of 300° to 1000° within 0 to 2 seconds 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 measuring 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 sleeve is attached to the inner wall of the exhaust section at one end close to the discharge section, and a second microwave suppression sleeve 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 arranged 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 a plurality of 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.

Images