Coal-based graphene preparation device and method

Abstract

According to the coal-based graphene preparation device and method provided by the invention, the preparation process is divided into three stages, namely a feeding stage, an oxidation stage and a hydrolysis stage, and a reaction kettle is controlled to add different materials in different stages. A stirrer is arranged in the reaction kettle and is used for stirring materials according to requirements at different stages. The jacket heat exchanger is arranged outside the reaction kettle, and the controller is used for controlling the jacket heat exchanger to work at different stages according to different temperature values, so that the temperature value in the reaction kettle can be matched with the temperature required by the different stages. According to the scheme, temperature control at different moments of the reaction link can be guaranteed, the control process is automatically achieved through the controller and is not affected by manual operation, it is guaranteed that experiments and products of different batches have reliable repeatability, and the test efficiency is improved. The process parameters of the graphene products produced in different batches are quantified and highly reliable, and the accurate control of the graphene preparation process is realized.

Description

Technical Field

[0001] The present application relates to the technical field of graphene preparation, and in particular to a coal-based graphene preparation device and method. Background Art

[0002] Graphene is a new type of two-dimensional carbon material with unique structural characteristics and excellent electrical, mechanical, optical and thermal properties. It has good application prospects in energy storage, catalysis, sensors and other fields. Therefore, in order to meet the increasing demand, cheap and controllable graphene preparation solutions are the key to the development and application of graphene materials.

[0003] At present, the raw material for preparing graphene is mainly natural flake graphite. With the rapid development and vigorous promotion of graphene technology, the raw material of graphene is bound to face a tense situation. Therefore, considering the relatively abundant coal resources, the existing technology has begun to study the preparation scheme of coal-based graphene. However, in the current research stage, the preparation of coal-based graphene is mainly based on manual experiments. The difference in operating experience of different personnel in each link of the experiment will lead to large differences in the quality of different batches of coal-based graphene products, relatively poor controllability, and a relatively random phenomenon. Summary of the invention

[0004] The technical problem to be solved by the present application is the technical problem of uncontrollable quality caused by differences in personnel operations in the existing coal-based graphene preparation process. To this end, the present application proposes a coal-based graphene preparation device and method.

[0005] In response to the above technical problems, this application provides the following technical solutions:

[0006] In a first aspect, the technical solution of the present application provides a coal-based graphene preparation device, comprising a reaction unit, wherein the reaction unit comprises:

[0007] A reactor, wherein a feed port is arranged on the top of the reactor and a stirrer is arranged inside the reactor; the feed port is used to add reaction materials into the reactor; wherein, in the feeding stage, the reaction materials include concentrated sulfuric acid, sodium nitrate and coal-based graphite, and the stirrer rotates at a speed matching the feed amount of the feed port; in the oxidation stage, the reaction materials include potassium permanganate, and the stirrer rotates at a speed matching the total amount of the materials; in the hydrolysis stage, the reaction materials include deionized water and hydrogen peroxide;

[0008] A jacket heat exchanger is arranged outside the reactor;

[0009] A controller connected to the jacket heat exchanger;

[0010] The controller controls the jacket heat exchanger to operate in a first temperature range during the feeding stage; controls the jacket heat exchanger to operate in a second temperature range during the oxidation stage; and controls the jacket heat exchanger to operate in a third temperature range during the hydrolysis stage.

[0011] In some schemes of the coal-based graphene preparation device, the first temperature range is 0-8°C; the second temperature range is a range adapted to the target oxidation temperature; and the third temperature range is above 90°C.

[0012] In some schemes of the coal-based graphene preparation device, when the controller controls the working temperature of the jacket heat exchanger to increase from the first temperature range to the second temperature range during the oxidation stage, the temperature change rate is not higher than the set rate, and the working temperature of the jacket heat exchanger is maintained for a set time after reaching the second temperature range.

[0013] In some schemes of the coal-based graphene preparation device, the controller controls the operating temperature of the jacket heat exchanger to increase from the second temperature range to the third temperature range within a set heating time during the hydrolysis stage.

[0014] The coal-based graphene preparation device described in some schemes also includes a centrifugal washing unit:

[0015] The centrifugal washing unit includes a filter, a tubular centrifuge and a pH analyzer;

[0016] The filter receives the reaction liquid output from the reactor and obtains the feed liquid after filtering the reaction liquid; the tubular centrifuge receives clean water and the feed liquid and separates the mixture of the clean water and the feed liquid into solid material and liquid material; the pH analyzer receives the liquid material and detects the pH value of the liquid material, and the tubular separator is closed if the pH value indicates that the liquid material is neutral.

[0017] The coal-based graphene preparation device described in some schemes also includes a dispersion unit:

[0018] The dispersion unit includes a slurry disperser, a slurry peristaltic pump, an ultrasonic disperser and a slurry storage tank;

[0019] The solid material separated by the tubular centrifuge is transported to the slurry disperser; the slurry disperser stirs the solid material for a preset time to obtain a stirred slurry, and the slurry peristaltic pump is used to transport the stirred slurry from the slurry disperser to the ultrasonic disperser; the top of the ultrasonic disperser is connected to compressed air to press the stirred slurry into the slurry storage tank;

[0020] The slurry disperser is equipped with a first level meter. When the first level meter detects that the slurry height in the slurry disperser reaches a first set height, the slurry peristaltic pump and the slurry disperser are automatically controlled to be turned off; the ultrasonic disperser is equipped with a second level meter. When the second level meter detects that the slurry height in the ultrasonic disperser reaches a second set height, the slurry is automatically stopped from being pressed into the slurry storage tank.

[0021] The coal-based graphene preparation device described in some schemes further includes a drying unit:

[0022] The drying unit comprises a cyclone dryer and a temperature sensor disposed at the inlet of the cyclone dryer, wherein the temperature sensor is used to detect the inlet temperature of the cyclone dryer;

[0023] The slurry storage tank of the dispersion unit is connected to the inlet of the cyclone dryer via a dryer peristaltic pump, and a product storage tank is arranged at the outlet of the cyclone dryer; when the inlet temperature detected by the temperature sensor reaches the set temperature, the dryer peristaltic pump is automatically turned on;

[0024] The slurry in the slurry storage tank is transported to the cyclone dryer for drying to obtain a solid product; the cyclone dryer transports the solid product to the product storage tank; the slurry storage tank is equipped with a third level meter, and when the third level meter detects that the slurry height in the slurry storage tank reaches a third set height, the dryer peristaltic pump is automatically turned off.

[0025] In a second aspect, the technical solution of the present application provides a method for preparing coal-based graphene, comprising the following steps:

[0026] Setting the start and end times of the feeding phase, oxidation phase and hydrolysis phase;

[0027] At the start time of the feeding stage, the jacket heat exchanger is automatically controlled to operate in the first temperature range, and the reactor is automatically controlled to add concentrated sulfuric acid, sodium nitrate and coal-based graphite; the stirrer rotates at a speed matching the feed amount of the feed inlet until the end time of the feeding stage;

[0028] At the start of the oxidation stage, the jacket heat exchanger is automatically controlled to operate in the second temperature range, and potassium permanganate is automatically controlled to be added to the reactor; the stirrer rotates at a speed matching the total amount of material until the end of the oxidation stage;

[0029] At the initial moment of the hydrolysis stage, the jacket heat exchanger is automatically controlled to operate in the third temperature range, and the reactor is automatically controlled to add deionized water and hydrogen peroxide until the end moment of the hydrolysis stage.

[0030] The method for preparing coal-based graphene described in some schemes further includes:

[0031] Setting a start time of the washing stage, wherein there is a first set time interval between the start time of the washing stage and the end time of the hydrolysis stage;

[0032] At the initial moment of the washing stage, deionized water is automatically added to the reactor, and the reactor is automatically controlled to output the reaction liquid to the filter in the centrifugal washing unit;

[0033] The tubular centrifuge in the centrifugal washing unit is automatically turned on; the filter filters the reaction liquid to obtain a feed liquid, and the feed liquid is transported to the tubular centrifuge; the tubular centrifuge receives clean water and the feed liquid and separates the mixture of the clean water and the feed liquid into a solid material and a liquid material;

[0034] The pH analyzer receives the liquid material and detects the pH value of the liquid material, takes the time when the pH value indicates that the liquid material is neutral as the end time of the washing stage, and closes the tubular separator at the end time of the washing stage.

[0035] The method for preparing coal-based graphene described in some schemes further includes:

[0036] Setting the initial time and the end time of the dispersion phase, wherein there is a second set time interval between the initial time of the dispersion phase and the end time of the washing phase;

[0037] At the initial moment of the dispersion stage, the slurry disperser, the slurry peristaltic pump and the ultrasonic disperser are automatically turned on; the slurry disperser stirs the solid material separated by the tubular centrifuge for a preset time to obtain a stirred slurry, and the slurry peristaltic pump is used to transport the stirred slurry from the slurry disperser to the ultrasonic disperser; the slurry height in the slurry disperser is automatically detected, and if the slurry height in the slurry disperser reaches a first set height, the slurry peristaltic pump and the slurry disperser are automatically controlled to be turned off;

[0038] The top of the ultrasonic disperser is connected to compressed air, and the stirred slurry is pressed into the slurry storage tank at the end of the dispersion stage; the slurry height in the ultrasonic disperser is automatically detected, and if the slurry height in the ultrasonic disperser reaches a second set height, the slurry is automatically stopped from being pressed into the slurry storage tank.

[0039] The method for preparing coal-based graphene described in some schemes further includes:

[0040] Setting the initial time and the end time of the drying stage, wherein there is a third set time interval between the initial time of the drying stage and the end time of the dispersion stage;

[0041] At the initial moment of the drying stage, the cyclone dryer is automatically turned on;

[0042] Detecting the inlet temperature of the cyclone dryer, if the inlet temperature reaches the set temperature, automatically turning on the dryer peristaltic pump, and the cyclone dryer dries the slurry transported by the slurry storage tank to obtain a solid product; detecting the slurry height in the slurry storage tank, if the slurry height in the slurry storage tank reaches a third set height, automatically turning off the dryer peristaltic pump;

[0043] At the end of the drying stage, the cyclone dryer delivers the solid product to the product storage tank.

[0044] The technical solution of this application has the following technical effects compared with the prior art:

[0045] The coal-based graphene preparation device and method provided in the present application divides the preparation process into three stages, namely, the feeding stage, the oxidation stage and the hydrolysis stage. The reactor can be automatically controlled to add different materials at different stages. A stirrer is provided inside the reactor, and the stirrer rotates as needed at different stages. A jacket heat exchanger is arranged outside the reactor, and the jacket heat exchanger is automatically controlled by a controller to work at different temperature values ​​at different stages, so that the temperature value in the reactor can match the temperature required at different stages. The above scheme of the present application can ensure the precise automatic control of the temperature at different times of the reaction link, and the control project is automatically realized by the controller and will not be affected by human operation, so as to ensure that experiments and products of different batches have reliable repeatability, ensure that the process parameters of graphene products produced in different batches have quantification and high reliability, and realize precise control of the graphene preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, which will help to understand the purpose and advantages of the present application, wherein:

[0047] Figure 1 This is a schematic structural diagram of a coal-based graphene preparation device according to an embodiment of the present application;

[0048] Figure 2 This is a flow chart of a method for preparing coal-based graphene according to an embodiment of the present application.

[0049] The meanings of the reference numerals are as follows:

[0050] 1-air compressor, 2-hydrogen peroxide tank, 3-deionized water tank, 4-hydrogen peroxide peristaltic pump, 5-deionized water peristaltic pump, 6-feeding port, 7-screw feeder, 8-jacketed heat exchanger, 9-controller, 10-filter, 11-tubular centrifuge, 12-wastewater tank, 13-slurry disperser, 14-slurry peristaltic pump, 15-ultrasonic disperser, 16-slurry storage tank, 17-dryer peristaltic pump, 18-cyclone dryer, 19-product storage tank, 20-PH analyzer. DETAILED DESCRIPTION

[0051] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0052] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0053] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0054] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0055] The present application embodiment provides a coal-based graphene preparation device, such as Figure 1As shown, the entire device is externally connected to an air compressor 1, a hydrogen peroxide tank 2, and a deionized water tank 3, which are used to provide different materials to the reactor at different reaction stages. Among them, a hydrogen peroxide peristaltic pump 4 is connected after the hydrogen peroxide tank to provide power for the hydrogen peroxide delivery, and a deionized water peristaltic pump 5 is connected after the deionized water tank 3 to provide power for the deionized water delivery. The above device is also connected to a screw feeder 7 for adding materials such as coal-based graphite and potassium perborate. Control valves are provided on each passage for adding materials, and the opening or closing of each control valve, the size of the opening, etc. correspond to the materials and the amount of materials that need to be added in each reaction stage.

[0056] like Figure 1 As shown, the device provided in this embodiment includes a reaction unit, and the reaction unit includes:

[0057] Reactor Y, a feed port is arranged on the top of the reactor Y, and an agitator is arranged inside; the feed port is used to add reaction materials into the reactor; the feed port of the present application may include multiple, and different feed ports are respectively connected to the conveying pipelines of different materials. Wherein, in the feeding stage, the reaction materials include concentrated sulfuric acid, sodium nitrate and coal-based graphite, and the agitator rotates at a speed matching the feed amount of the feed port; in the oxidation stage, the reaction materials include potassium permanganate, and the agitator rotates at a speed matching the total amount of materials; in the hydrolysis stage, the reaction materials include deionized water and hydrogen peroxide. The agitator rotates as needed at different stages, and the agitator itself is equipped with a control system, and the stirring speed can be set by operating the control system of the agitator, so that the agitator runs at a stirring speed that meets the needs at different stages.

[0058] The jacket heat exchanger 8 is arranged outside the reactor Y.

[0059] The controller 9 is connected to the jacket heat exchanger 8; the controller 9 controls the jacket heat exchanger 8 to operate in the first temperature range during the feeding stage; controls the jacket heat exchanger 8 to operate in the second temperature range during the oxidation stage; and controls the jacket heat exchanger 8 to operate in the third temperature range during the hydrolysis stage.

[0060] In the present application, the temperature operating range of the jacket heat exchanger 8 is -15°C to 200°C. During the feeding stage, the first temperature range is 0-8°C, preferably 0-5°C; the second temperature range is a range adapted to the target oxidation temperature, preferably 35°C, which can be pre-set in the controller 9; the third temperature range is above 90°C, preferably 98°C.

[0061] During the feeding stage, concentrated sulfuric acid (mass fraction 98%, 1000 mL) and sodium nitrate (25 g) were added in sequence from a feeding port 6 of the reactor Y; the rotation speed of the agitator was 200 r / min, coal-based graphite (30 g) was added by means of a screw feeder 7, the screw rotation speed of the screw feeder 7 was adjusted, the feeding speed of the coal-based graphite was controlled to be 3 g / min, and the valve F3 was closed after the feeding was completed; the temperature in the reactor Y was controlled to be less than 5° C. and stirred for 30 min.

[0062] During the oxidation stage, 150 g of potassium permanganate is added to the reactor Y through the screw feeder 7, the screw speed of the screw feeder 7 is adjusted, the feeding rate of potassium permanganate is controlled to be 5 g / min, and the feeding time of potassium permanganate is controlled to be 30 min. After the feeding is completed, the screw feeder 7 is turned off, and the temperature of the jacket heat exchanger 8 is increased from 5°C to 35°C through the controller 9. In specific implementation, the controller 9 controls the temperature change rate of the jacket heat exchanger 8 from the first temperature range to the second temperature range during the oxidation stage to be no higher than the set speed, and the working temperature of the jacket heat exchanger 8 is maintained for a set time when it reaches the second temperature range. Preferably, the heating time is 30 min, and the constant temperature is maintained for 240 min after reaching 35°C. During the hydrolysis stage, valve F5 and deionized water peristaltic pump 5 were opened, 1500 ml of deionized water was added to reactor Y, the speed of deionized water peristaltic pump 5 was controlled to be 12 r / min, the water inlet time was 30 min, and valve F5 and deionized water peristaltic pump 5 were closed after the water inlet was completed.

[0063] In the hydrolysis stage, the controller 9 controls the working temperature of the jacket heat exchanger 8 to increase from the second temperature range to the third temperature range within the set heating time. The temperature of the jacket heat exchanger 8 is raised to 98°C by the controller 9, and the heating time is controlled to be 30 minutes. After the temperature reaches 98°C, the valve F4 and the hydrogen peroxide peristaltic pump 4 are opened, and 120ml of hydrogen peroxide is added to the reactor Y. The speed of the hydrogen peroxide peristaltic pump 4 is controlled to be 6r / min, and the hydrogen peroxide feeding time is 10 minutes. After the water feeding is completed, the valve F4 and the hydrogen peroxide peristaltic pump 4 are closed. After the reaction for 30 minutes, the reaction process ends.

[0064] The above scheme of the present embodiment divides the preparation process into three stages, namely, the feeding stage, the oxidation stage and the hydrolysis stage, and controls the reactor to add different materials at different stages. An agitator is provided inside the reactor, and the agitator rotates as needed at different stages. A jacketed heat exchanger is provided outside the reactor, and a controller is used to control the jacketed heat exchanger to work at different temperature values ​​at different stages, so that the temperature value in the reactor can match the temperature required at different stages. The above scheme of the present application can ensure the control of temperature at different times in the reaction link, and the control project is automatically realized by the controller and will not be affected by human operation, ensuring that experiments and products of different batches have reliable repeatability, ensuring that the process parameters of graphene products produced in different batches have quantification and high reliability, and realizing precise control of the graphene preparation process.

[0065] Furthermore, if Figure 1 As shown, the device also includes a centrifugal washing unit. The centrifugal washing unit includes a filter 10, a tubular centrifuge 11 and a pH analyzer 20; the filter 10 receives the reaction liquid output from the reactor and obtains a feed liquid after filtering the reaction liquid; the tubular centrifuge 11 receives clean water and the feed liquid and separates the mixture of the clean water and the feed liquid into solid materials and liquid materials; the pH analyzer 20 receives the liquid material and detects the pH value of the liquid material, and the tubular separator 11 is closed if the pH value indicates that the liquid material is neutral. After the reaction is completed, compressed air is introduced into the reactor Y through the air compressor 1, and the reaction liquid in the reactor Y is pressed into the filter 10 by pressure. The feed liquid filtered by the filter 10 enters the tubular centrifuge 11 to achieve solid-liquid separation by centrifugation. The fixed speed of the tubular centrifuge 11 is set, and the clean water pump is started to pass clean water to the tubular centrifuge 11 for washing. The water inlet flow rate is set, and the wastewater generated by the tubular centrifuge 11 enters the wastewater storage tank 12. When the pH value of the wastewater centrifuged by the tubular centrifuge 11 is neutral, that is, when the detection result of the pH analyzer 20 is about 7, the tubular centrifuge 11 and the clean water pump are turned off, and the centrifuge drum is disassembled after the tubular centrifuge 11 stops rotating, and the solids in the drum are cleaned out.

[0066] Preferably, the device further comprises a dispersion unit, which comprises a slurry disperser 13, a slurry peristaltic pump 14, an ultrasonic disperser 15 and a slurry storage tank 16; the solid material separated by the tubular centrifuge 11 is transported to the slurry disperser 13; the slurry disperser 13 stirs the solid material for a preset time to obtain a stirred slurry, and the slurry peristaltic pump 14 is used to transport the stirred slurry from the slurry disperser 13 to the ultrasonic disperser 15; the top of the ultrasonic disperser 15 is connected to compressed air to press the stirred slurry into the slurry storage tank 16. The slurry disperser 13 is equipped with a first material level meter, which automatically controls the slurry peristaltic pump 14 and the slurry disperser 13 to shut down when the first material level meter detects that the slurry height in the slurry disperser reaches a first set height; the ultrasonic disperser 15 is equipped with a second material level meter, which automatically stops pressing the slurry into the slurry storage tank 16 when the second material level meter detects that the slurry height in the ultrasonic disperser reaches a second set height. In this solution, a slurry peristaltic pump 14 is arranged between the slurry disperser 13 and the ultrasonic disperser 15, and the top of the ultrasonic disperser 15 is connected to the compressed air of the air compressor 1. The solid material cleaned out by the centrifuge 11 is added to the slurry disperser 13, the clean water pump is turned on to add a fixed amount of clean water to the slurry disperser 13, the stirring speed of the slurry disperser 13 is set, and the agitator is turned on for a fixed time of dispersion. After the agitator finishes stirring, the slurry peristaltic pump 14 is turned on to send all the slurry to the ultrasonic disperser 15, the ultrasonic disperser 15 is started, the working time of the ultrasonic disperser 15 is set, and after the working time is completed, the compressed air valve F1 on the top of the ultrasonic disperser 15 and the valve F10 of the slurry storage tank 16 are started to send all the slurry into the slurry storage tank 16 by pressure.

[0067] The device also includes a drying unit, which includes a cyclone dryer 18 and a temperature sensor disposed at the inlet of the cyclone dryer, and the temperature sensor is used to detect the inlet temperature of the cyclone dryer 18. The slurry storage tank 16 of the dispersion unit is connected to the inlet of the cyclone dryer 18 via a dryer peristaltic pump 17, and a product storage tank 19 is disposed at the outlet of the cyclone dryer 18; when the inlet temperature detected by the temperature sensor reaches the set temperature, the dryer peristaltic pump 17 is automatically turned on; the slurry in the slurry storage tank 19 is transported to the cyclone dryer 18 for drying to obtain a solid product; the cyclone dryer 18 transports the solid product to the product storage tank 19. Preferably, the product storage tank 19 is provided with a vent, and the vent is turned on for ventilation and cooling and maintained for a set ventilation time to obtain a graphene product. In specific implementation, the inlet temperature of the cyclone dryer 18 is set to be not less than 200°C. When the temperature reaches 180°C, the dryer peristaltic pump 17 is turned on, the feed speed is set, and the slurry in the slurry storage tank 16 is transported to the cyclone dryer 18, and the dried solid product enters the product storage tank 19. After all the products enter the product storage tank 19, the product storage tank 19 is continuously ventilated and cooled for a fixed time, and the graphene oxide product can be obtained.

[0068] The present application embodiment provides a method for preparing coal-based graphene, such as Figure 2 As shown, the following steps are included:

[0069] The parameter setting stage is used to set the start and end time of the feeding stage, oxidation stage and hydrolysis stage; set the start time of the washing stage; set the initial and end time of the dispersion stage; set the initial and end time of the drying stage. In the specific implementation, when different stages are connected, the interval time can be set between the two stages, and the interval time can be set according to the experience value.

[0070] Reaction stage: at the start of the feeding stage, the jacket heat exchanger is automatically controlled to operate in the first temperature range, and the reactor is automatically controlled to add concentrated sulfuric acid, sodium nitrate and coal-based graphite; the stirrer rotates at a speed matching the feed amount of the feed inlet until the end of the feeding stage;

[0071] At the start of the oxidation stage, the jacket heat exchanger is automatically controlled to operate in the second temperature range, and potassium permanganate is automatically controlled to be added to the reactor; the stirrer rotates at a speed matching the total amount of material until the end of the oxidation stage;

[0072] At the initial moment of the hydrolysis stage, the jacket heat exchanger is automatically controlled to operate in the third temperature range, and the reactor is automatically controlled to add deionized water and hydrogen peroxide until the end moment of the hydrolysis stage.

[0073] In the washing stage, at the initial moment of the washing stage, deionized water is automatically added into the reactor, and the reactor is automatically controlled to output the reaction liquid to the filter in the centrifugal washing unit; the tubular centrifuge in the centrifugal washing unit is automatically turned on; the filter filters the reaction liquid to obtain a feed liquid, and the feed liquid is transported to the tubular centrifuge, the tubular centrifuge receives clean water and the feed liquid and separates the mixture of the clean water and the feed liquid into solid material and liquid material; a pH analyzer receives the liquid material and detects the pH value of the liquid material, and the moment when the pH value indicates that the liquid material is neutral is taken as the end moment of the washing stage, and the tubular separator is closed at the end moment of the washing stage.

[0074] The dispersion stage includes: at the initial moment of the dispersion stage, automatically starting the slurry disperser, the slurry peristaltic pump and the ultrasonic disperser; the slurry disperser stirs the solid material separated by the tubular centrifuge for a preset time to obtain a stirred slurry, and the slurry peristaltic pump is used to transport the stirred slurry from the slurry disperser to the ultrasonic disperser; automatically detecting the slurry height in the slurry disperser, and if the slurry height in the slurry disperser reaches a first set height, automatically controlling the slurry peristaltic pump and the slurry disperser to be closed; the top of the ultrasonic disperser is connected to compressed air, and the stirred slurry is pressed into the slurry storage tank at the end of the dispersion stage; automatically detecting the slurry height in the ultrasonic disperser, and if the slurry height in the ultrasonic disperser reaches a second set height, automatically stopping pressing the slurry into the slurry storage tank.

[0075] The drying stage includes automatically starting the cyclone dryer at the initial moment of the drying stage; detecting the inlet temperature of the cyclone dryer, and if the inlet temperature reaches the set temperature, automatically starting the dryer peristaltic pump, and the cyclone dryer dries the slurry transported from the slurry storage tank to obtain a solid product; detecting the slurry height in the slurry storage tank, and if the slurry height in the slurry storage tank reaches a third set height, automatically turning off the dryer peristaltic pump; at the end moment of the drying stage, the cyclone dryer transports the solid product to the product storage tank.

[0076] In practical application, a brief summary of the different stages in a specific example of the process in this scheme is shown in Table 1:

[0077] Table 1 Control flow

[0078]

[0079]

[0080] Combination Figure 1 As shown in Table 1, a complete process for preparing graphene using the above method of the present application includes:

[0081] The reaction process is divided into the feeding stage, the oxidation stage and the hydrolysis stage.

[0082] In the feeding stage, the temperature of the reactor is set at 0-5°C, and concentrated sulfuric acid (mass fraction 98%, 1000mL) and sodium nitrate (25g) are added in sequence from the reactor feed port; the stirrer speed is automatically controlled to 200r / min, coal-based graphite (30g) is automatically added by the screw feeder 7, the screw speed is automatically adjusted, and the coal-based graphite feeding speed is automatically controlled to be 3g / min. After the feeding is completed, the valve F3 is closed; the temperature in the reactor is automatically controlled to be less than 5°C and stirred for 30min; in the oxidation stage, the screw feeder 7 automatically adds 150g of potassium permanganate to the reactor, the screw speed is automatically adjusted, the potassium permanganate feeding speed is controlled to be 5g / min, and the feeding time is controlled The time is 30min. After the feeding is completed, the screw feeder 7 is turned off. The temperature in the reactor is automatically controlled to rise from 5°C to 35°C. The heating time is 30min. After reaching 35°C, the constant temperature is maintained for 240min. In the hydrolysis stage, 1500ml of deionized water is added to the reactor, the speed of the peristaltic pump is automatically controlled to be 12r / min, the water inlet time is 30min, the temperature in the reactor is automatically controlled to rise to 98°C, and the heating time is controlled to be 30min. After the temperature reaches this temperature, 120ml of hydrogen peroxide is added to the reactor, the speed of the peristaltic pump is automatically controlled to be 6r / min, the hydrogen peroxide inlet time is 10min, and after reacting for 30min, the reaction process is completed.

[0083] In the washing stage, the liquid flowing through the filter 10 enters the tubular centrifuge 11, and solid-liquid separation is achieved by centrifugation, and the wastewater enters the wastewater tank 12. In the specific implementation, the filter 10 can be provided with a liquid level meter. When the liquid level meter shows a low level, the deionized water peristaltic pump 5 and valves F7 and F8 can be started, and the peristaltic pump speed is set to 150r / min. The inlet pipeline of the wastewater tank 12 is provided with a pH analyzer 20. When the pH value is 7, the washing stage can be ended.

[0084] In the dispersion stage, the tubular centrifuge 11 is turned off to clean out the solids in the drum. The solids taken out from the tubular centrifuge 11 are added to the slurry disperser 13, the deionized water peristaltic pump 5 is automatically started, valves F7 and F9 are opened, and the peristaltic pump speed is set to 100 r / min. After 5 minutes of water intake, turn off the deionized water peristaltic pump 5 and valves F7 and F9. Valve F10 is currently closed. Start the slurry dispersion, 13 agitator, set the stirring speed to 1000rpm, and the dispersion time to 10 minutes; turn on the slurry peristaltic pump 14 and set it to 150r / min, and send all the slurry into the ultrasonic disperser 15. The slurry disperser 13 is equipped with a level meter. When the level meter is low, turn off the slurry peristaltic pump 14 and the agitator of the slurry disperser 13. Start the ultrasonic disperser 15 at the same time, and turn off the ultrasonic disperser 15 after 1 hour of ultrasonic dispersion; turn on the air compressor after a delay of 5s, and delay for 5s; open valve F1, and delay for 5s; open valve F10, and send all the slurry into the slurry storage tank 16 by compressed air pressure. The ultrasonic disperser 15 is equipped with a level meter. When the level meter is low, turn off valve F1 and air compressor 1, delay for 5s, and close valve F10. At this time, all the slurry in the ultrasonic disperser 15 enters the slurry storage tank 16.

[0085] In the drying stage, after closing valve F10, the cyclone dryer 18 is automatically started with a delay of 5s, and the inlet temperature of the cyclone dryer 18 is set to 250°C; when the inlet temperature reaches 180°C, the dryer peristaltic pump 17 is started, and the feed rate is set to 15mL / min, and the slurry in the slurry storage tank 16 enters the cyclone dryer 18. The product storage tank 19 is set at the outlet of the cyclone dryer 18 to collect the solid product. The slurry storage tank 16 is equipped with a level meter. When the level meter is low, the dryer peristaltic pump 17 is turned off, and the delay is 20min; the cyclone dryer 18 is turned off. The finished product collection tank of the product storage tank 19 is ventilated and cooled for 30min, and the graphene oxide product is taken out.

[0086] The scheme in the above embodiment sets the start time and end time of each stage in advance, takes time as the main control line and material level control as the auxiliary line, realizes the time requirements between different links of the entire preparation process and the effectiveness of equipment operation connection, and realizes an accurate operation process.

[0087] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A coal-based graphene preparation device, characterized in that: The invention comprises a reaction unit, wherein the reaction unit comprises: A reactor, wherein a feed port is arranged on the top of the reactor and a stirrer is arranged inside the reactor; the feed port is used to add reaction materials into the reactor; wherein, in the feeding stage, the reaction materials include concentrated sulfuric acid, sodium nitrate and coal-based graphite, and the stirrer rotates at a speed matching the feed amount of the feed port; in the oxidation stage, the reaction materials include potassium permanganate, and the stirrer rotates at a speed matching the total amount of the materials; in the hydrolysis stage, the reaction materials include deionized water and hydrogen peroxide; A jacket heat exchanger is arranged outside the reactor; A controller connected to the jacket heat exchanger; The controller controls the jacket heat exchanger to operate in a first temperature range during the feeding stage; controls the jacket heat exchanger to operate in a second temperature range during the oxidation stage; and controls the jacket heat exchanger to operate in a third temperature range during the hydrolysis stage.

2. The coal-based graphene preparation device according to claim 1, characterized in that: The first temperature range is 0-8°C; the second temperature range is a range adapted to the target oxidation temperature; and the third temperature range is above 90°C.

3. The coal-based graphene preparation device according to claim 2, characterized in that: When the controller controls the working temperature of the jacket heat exchanger to increase from the first temperature range to the second temperature range during the oxidation stage, the temperature change rate is not higher than the set rate, and the working temperature of the jacket heat exchanger is maintained for a set time after reaching the second temperature range.

4. The coal-based graphene preparation device according to claim 1, characterized in that: The controller controls the operating temperature of the jacket heat exchanger to increase from the second temperature range to the third temperature range within a set temperature increase time during the hydrolysis stage.

5. The coal-based graphene preparation device according to any one of claims 1 to 4, characterized in that: Also includes centrifugal washing unit: The centrifugal washing unit includes a filter, a tubular centrifuge and a pH analyzer; The filter receives the reaction liquid output from the reactor and obtains the feed liquid after filtering the reaction liquid; the tubular centrifuge receives clean water and the feed liquid and separates the mixture of the clean water and the feed liquid into solid material and liquid material; the pH analyzer receives the liquid material and detects the pH value of the liquid material, and the tubular separator is closed if the pH value indicates that the liquid material is neutral.

6. The coal-based graphene preparation device according to claim 5, characterized in that: Also includes decentralized units: The dispersion unit includes a slurry disperser, a slurry peristaltic pump, an ultrasonic disperser and a slurry storage tank; The solid material separated by the tubular centrifuge is transported to the slurry disperser; The slurry disperser stirs the solid material for a preset time to obtain a stirred slurry, and the slurry peristaltic pump is used to transport the stirred slurry from the slurry disperser to the ultrasonic disperser; The top of the ultrasonic disperser is connected to compressed air to press the stirred slurry into the slurry storage tank; The slurry disperser is equipped with a first level meter. When the first level meter detects that the slurry height in the slurry disperser reaches a first set height, the slurry peristaltic pump and the slurry disperser are automatically controlled to be shut down; the ultrasonic disperser is equipped with a second level meter. When the second level meter detects that the slurry height in the ultrasonic disperser reaches a second set height, the slurry is automatically stopped from being pressed into the slurry storage tank.

7. The coal-based graphene preparation device according to claim 6, characterized in that: Also includes drying unit: The drying unit comprises a cyclone dryer and a temperature sensor disposed at the inlet of the cyclone dryer, wherein the temperature sensor is used to detect the inlet temperature of the cyclone dryer; The slurry storage tank of the dispersion unit is connected to the inlet of the cyclone dryer via a dryer peristaltic pump, and a product storage tank is arranged at the outlet of the cyclone dryer; when the inlet temperature detected by the temperature sensor reaches the set temperature, the dryer peristaltic pump is automatically turned on; The slurry in the slurry storage tank is transported to the cyclone dryer for drying to obtain a solid product; the cyclone dryer transports the solid product to the product storage tank; the slurry storage tank is equipped with a third level meter, and when the third level meter detects that the slurry height in the slurry storage tank reaches a third set height, the dryer peristaltic pump is automatically turned off.

8. The coal-based graphene preparation device according to claim 7, characterized in that: The product storage tank is provided with a ventilating hole, and the graphene product is obtained after the ventilating hole is turned on for ventilation and cooling function and maintained for a set ventilation time.

9. A method for preparing coal-based graphene, characterized in that: The steps include: Setting the start and end times of the feeding phase, oxidation phase and hydrolysis phase; At the start time of the feeding stage, the jacket heat exchanger is automatically controlled to operate in the first temperature range, and the reactor is automatically controlled to add concentrated sulfuric acid, sodium nitrate and coal-based graphite; the stirrer rotates at a speed matching the feed amount of the feed inlet until the end time of the feeding stage; At the start of the oxidation stage, the jacket heat exchanger is automatically controlled to operate in the second temperature range, and potassium permanganate is automatically controlled to be added to the reactor; the stirrer rotates at a speed matching the total amount of material until the end of the oxidation stage; At the initial moment of the hydrolysis stage, the jacket heat exchanger is automatically controlled to operate in the third temperature range, and the reactor is automatically controlled to add deionized water and hydrogen peroxide until the end moment of the hydrolysis stage.

10. The method for preparing coal-based graphene according to claim 9, characterized in that: Also includes: Setting a start time of the washing stage, wherein there is a first set time interval between the start time of the washing stage and the end time of the hydrolysis stage; At the initial moment of the washing stage, deionized water is automatically added to the reactor, and the reactor is automatically controlled to output the reaction liquid to the filter in the centrifugal washing unit; The tubular centrifuge in the centrifugal washing unit is automatically turned on; the filter filters the reaction liquid to obtain a feed liquid, and the feed liquid is transported to the tubular centrifuge; the tubular centrifuge receives clean water and the feed liquid and separates the mixture of the clean water and the feed liquid into a solid material and a liquid material; The pH analyzer receives the liquid material and detects the pH value of the liquid material, takes the time when the pH value indicates that the liquid material is neutral as the end time of the washing stage, and closes the tubular separator at the end time of the washing stage.

11. The method for preparing coal-based graphene according to claim 10, characterized in that: Also includes: Setting the initial time and the end time of the dispersion phase, wherein there is a second set time interval between the initial time of the dispersion phase and the end time of the washing phase; At the initial moment of the dispersion stage, the slurry disperser, the slurry peristaltic pump and the ultrasonic disperser are automatically turned on; The slurry disperser stirs the solid material separated by the tubular centrifuge for a preset time to obtain a stirred slurry, and the slurry peristaltic pump is used to transport the stirred slurry from the slurry disperser to the ultrasonic disperser; the slurry height in the slurry disperser is automatically detected, and if the slurry height in the slurry disperser reaches a first set height, the slurry peristaltic pump and the slurry disperser are automatically controlled to be turned off; The top of the ultrasonic disperser is connected to compressed air, and the stirred slurry is pressed into the slurry storage tank at the end of the dispersion stage; the slurry height in the ultrasonic disperser is automatically detected, and if the slurry height in the ultrasonic disperser reaches a second set height, the slurry is automatically stopped from being pressed into the slurry storage tank.

12. The method for preparing coal-based graphene according to claim 11, characterized in that: Also includes: Setting the initial time and the end time of the drying stage, wherein there is a third set time interval between the initial time of the drying stage and the end time of the dispersion stage; At the initial moment of the drying stage, the cyclone dryer is automatically turned on; Detecting the inlet temperature of the cyclone dryer, if the inlet temperature reaches the set temperature, automatically turning on the dryer peristaltic pump, and the cyclone dryer dries the slurry transported by the slurry storage tank to obtain a solid product; detecting the slurry height in the slurry storage tank, if the slurry height in the slurry storage tank reaches a third set height, automatically turning off the dryer peristaltic pump; At the end of the drying stage, the cyclone dryer delivers the solid product to the product storage tank.

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