CN113929089A - Novel method for preparing graphene on large scale - Google Patents

Novel method for preparing graphene on large scale Download PDF

Info

Publication number
CN113929089A
CN113929089A CN202111435152.0A CN202111435152A CN113929089A CN 113929089 A CN113929089 A CN 113929089A CN 202111435152 A CN202111435152 A CN 202111435152A CN 113929089 A CN113929089 A CN 113929089A
Authority
CN
China
Prior art keywords
ball milling
kettle
pressure
graphene
shearing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202111435152.0A
Other languages
Chinese (zh)
Inventor
赵亚平
谭慧君
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shanghai Jiaotong University
Original Assignee
Shanghai Jiaotong University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shanghai Jiaotong University filed Critical Shanghai Jiaotong University
Priority to CN202111435152.0A priority Critical patent/CN113929089A/en
Publication of CN113929089A publication Critical patent/CN113929089A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/184—Preparation
    • C01B32/19—Preparation by exfoliation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2204/00—Structure or properties of graphene
    • C01B2204/20—Graphene characterized by its properties
    • C01B2204/32—Size or surface area
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Nanotechnology (AREA)
  • Inorganic Chemistry (AREA)
  • Carbon And Carbon Compounds (AREA)

Abstract

The invention relates to a novel method for preparing graphene on a large scale, which comprises the following steps: (1) putting graphite raw materials and ball milling beads into a high-pressure ball milling kettle, and passing through high-pressure CO2Pumping CO into the high-pressure ball milling kettle by a pump2Venting air and bringing the system to a set pressure to form supercritical CO2Performing ball milling pretreatment on the graphite raw material; (2) keeping the ball mill open, and opening high-pressure CO2Pump, the graphite raw material pretreated in the high-pressure ball milling kettle is processed by supercritical CO2And blowing the mixture into a high-pressure shearing kettle, shearing the mixture, finishing the experiment after the components in the ball milling kettle are transferred, and collecting the product in the shearing kettle to obtain high-quality graphene, namely the target product. Compared with the prior art, the invention adopts supercritical CO2The ball-milling pre-stripping serial shearing treatment is carried out on the graphite raw material in the atmosphere to prepare the high-quality graphene, the operation is simple, the environment is protected, the efficiency is high, and the continuous stripping, collection and the like of the large-batch high-quality graphene can be realized.

Description

Novel method for preparing graphene on large scale
Technical Field
The invention belongs to the technical field of graphene nanomaterial preparation, and relates to a novel method for preparing graphene on a large scale.
Background
Graphene has high electron transfer rate, high thermal conductivity, high electrical conductivity and strong mechanical properties as a novel two-dimensional nanostructure, so that the graphene has great application potential in the fields of supercapacitors, transistors, flexible displays, new energy batteries, aerospace, electronic computers and the like. However, in the current research, a redox method or a CVD method is mostly adopted for preparing graphene, the prepared graphene has a reduced conductivity due to the damage of an in-plane lattice structure, or the yield is extremely low due to equipment limitation, and the mass preparation of high-quality graphene always limits the production and application of graphene.
The supercritical fluid is used as a novel green and safe solvent, and is gradually becoming an excellent system for preparing graphene due to high permeability and diffusion coefficient. Wang et al (W.Wang, Y.Gai, N.Song, D.Xiao and Y.ZHao, Industrial)&Engineering Chemistry Research,57,16701(2018), by supercritical CO2High-quality graphene with high purity is prepared in a coupled ultrasonic and shearing mode, but the processing capacity is only 0.1g, and the requirement of downstream application can not be met. Gai et al (Y.gai, W.Wang, X.Ding, H.Tan, M.Lin and Y.ZHao, Industrial)&Engineering Chemistry Research,57,8220 (2018.) the yield of graphene was further improved by designing different shear rotors, but the single batch throughput was only 1 g. Song et al (N.Song, J.jia, W.Wang, Y.Gao, Y.ZHao and Y.Chen, Chemical Engineering Journal,298,198 (2016)) first pre-treated the graphite starting material by means of surfactants and ball milling, followed by supercritical CO2The method can improve the treatment capacity to a certain extent, but the surface of the obtained graphene is covered with a layer of surfactant which is difficult to remove, thereby limiting the subsequent application of the graphene. The existing technology for preparing graphene in supercritical fluid is not beneficial to subsequent application due to complex pretreatment (CN201110067543.1), complex operation and harsh conditions (CN201610679367, XCN201110021033.0), the need of adding a surfactant (CN201210001582.6) or a stabilizer (CN201110354756.2) in the system and the like. More notably, the current graphene preparation technology is all intermittent operation, and no continuous preparation technology suitable for industrial scale-up production is reported yet. Therefore, how to continuously prepare high-quality graphene in large batch is still the first difficult problem restricting the application of graphene.
Disclosure of Invention
The invention aims to provide a novel method for preparing graphene in large scale by supercritical CO2Ball milling and pre-stripping are carried out on graphite raw materials in the atmosphere, high-quality graphene is prepared by connecting shearing and stripping equipment in series,the method is simple to operate, green and efficient, and can realize large-scale continuous production through industrial amplification.
The purpose of the invention can be realized by the following technical scheme:
a novel method for preparing graphene on a large scale comprises the following steps:
(1) putting graphite raw materials and ball milling beads into a high-pressure ball milling kettle, and passing through high-pressure CO2Pumping CO into the high-pressure ball milling kettle by a pump2Venting air and bringing the system to a set pressure to form supercritical CO2Performing ball milling pretreatment on the graphite raw material;
(2) keeping the ball mill open, and opening high-pressure CO2Pump, the graphite raw material pretreated in the high-pressure ball milling kettle is processed by supercritical CO2Purging and entering a high-pressure shearing kettle, simultaneously starting a shearing rotor to carry out shearing treatment, ending the experiment after the components in the ball milling kettle are transferred, and collecting the product in the shearing kettle to obtain high-quality graphene, namely the target product.
Further, the graphite raw material is one or more of natural graphite, expanded graphite and flake graphite.
Further, the graphite raw material is present in the form of a dry raw material or a graphite dispersion liquid containing a solvent in a high-pressure ball mill kettle. Solvents herein include, but are not limited to, ethanol, deionized water, and the like.
Further, the mass of the graphite raw material depends on the volume of the ball milling kettle, and generally, the volume ratio of the graphite raw material to the high-pressure ball milling kettle is controlled to be 10-100g/L, and preferably 40 g/L.
Furthermore, the ball milling beads are made of one or more of stainless steel, zirconia, alumina, agate, polyurethane-coated iron cores, hard alloys and the like, and are preferably zirconia ball milling beads. Meanwhile, the diameter of the ball grinding bead is 0.1-20 mm, preferably 1-15 mm.
Furthermore, the ratio of the volume of the ball milling beads to the volume of the high-pressure ball milling kettle is controlled to be 0.1-0.8: 1, and preferably 0.3-0.6: 1.
Further, during ball milling pretreatment, the temperature in the high-pressure ball milling kettle is 33-100 ℃, and preferably 40-65 ℃; the pressure in the high-pressure ball milling kettle is 8-50 Mpa, preferably 12-25 Mpa; the rotating speed of the stirring paddle in the high-pressure ball milling kettle is 300-5000 rpm, preferably 600-2000 rpm; the ball milling pretreatment time is 12-72 h, preferably 12-48 h.
Further, during shearing treatment, the pressure and the temperature in the high-pressure shearing kettle are kept consistent with those of the ball milling kettle, wherein the pressure is 8-50 Mpa, and preferably 12-25 Mpa; the temperature is 33-100 ℃, and preferably 40-65 ℃; the shear rotation speed is 500-4000rpm, preferably 1000-2000 rpm; the shearing time is 2-72 h, preferably 6-24 h.
Further, in the process of transferring the pretreated graphite raw material from the high-pressure ball milling kettle to the high-pressure shearing kettle, controlling CO2The flow rate of (A) is 5-50kg/h, preferably 10-30 kg/h.
Further, in the process of transferring the pretreated graphite raw material from the high-pressure ball milling kettle to the high-pressure shearing kettle, CO is added2The graphite raw material taken out is intercepted in a high-pressure shearing kettle, and CO2Then high pressure CO is returned2The inlet of the pump is recycled.
Furthermore, the obtained high-quality graphene can be stored in a dry state or in a solvent, and the solvent can be ethanol, deionized water and the like.
In the stripping method, the graphite raw material is firstly pretreated in the supercritical ball milling kettle, under the impact and crushing action of high-speed moving ball milling beads, the size and thickness of a lamella of the graphite raw material are reduced, a large number of irregular defects are generated at the edge, the lamella is tilted, the interlayer spacing is increased, and the shearing force action and CO in the subsequent stripping process are facilitated2Molecules penetrate between the layers. The high-pressure ball milling kettle and the shearing kettle are connected by a pipeline, and the pre-stripped graphite raw material is always in supercritical CO in the process of transferring from the ball milling system to the shearing system2Atmospheric, high pressure CO2The atmosphere can inhibit the permeation of CO between graphite layers2The molecule escapes, and simultaneously the peeled graphene can be inhibited from being aggregated again, thereby solving the problem of secondary aggregation of the graphene easily caused in the process of transferring the traditional pretreatment system to the peeling system, and avoiding the surface activityThe use of the agent improves the quality of the obtained graphene product. In the transfer process, the graphite raw material with smaller size after pre-stripping is preferentially blown into the shearing kettle, and the residual graphite raw material with large size is left in the kettle for continuous ball milling treatment, so that the mass transfer effect and the pre-stripping efficiency in the ball milling process are improved. In a high pressure shear reactor, the velocity gradient generated by the high velocity difference between the stator and rotor is in supercritical CO2Shear stress is generated in the fluid and acts on the edge of the graphite to be stripped, so that interlayer slippage is generated to strip the graphite; at the same time, CO permeates into the graphite layers2The molecules can weaken the van der waals force between layers of graphite, further promote the stripping of the graphite, and obtain high-quality graphene.
Compared with the prior art, the method realizes the continuity of the graphene stripping technology for the first time, and innovatively provides the supercritical CO2Ball milling pretreatment method and its application in supercritical CO2The shearing technologies are connected in series, so that the stripping efficiency can be improved, the agglomeration of graphene in the transfer process is avoided, the long-term continuous high-quality graphene preparation and product collection are realized, and the single-batch raw material treatment capacity is greatly improved.
Drawings
Fig. 1 is a flow diagram of graphene preparation of example 1;
FIG. 2 is an SEM photograph of a sample prepared in example 1;
FIG. 3 is a TEM image of a sample prepared in example 2;
fig. 4 is a Raman picture of a sample prepared in example 3.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
In the following examples, unless otherwise specified, all the conventional commercially available raw materials or conventional processing techniques in the art are indicated.
Example 1
Reference is made to the Process flow of FIG. 1Adding 40g of natural graphite into a high-pressure stainless steel ball milling kettle with the volume of 1L, adding 800g of stainless steel balls with the diameter of 3mm, and screwing down a kettle cover. Controlling the temperature of the ball milling kettle at 50 ℃, and passing through a high-pressure plunger pump (namely high-pressure CO)2Pump) pumps a certain amount of CO into the system2The air in the system is discharged, and then CO is continuously pumped in2Until the system pressure is 12 MPa. Opening the stirring paddle of the ball milling kettle, controlling the rotating speed of the stirring paddle to be 3000rpm, and performing supercritical CO2And carrying out ball milling treatment on the graphite raw material in the system for 24 hours. Then, opening an outlet valve of the ball milling kettle and a high-pressure plunger pump (communicated with each other through a pipeline) while not closing a stirring paddle of the ball milling kettle, and controlling CO2The mass flow is 10kg/h, so that a sample in the ball milling kettle is subjected to continuous supercritical CO2And blowing the mixture into a high-pressure shearing kettle, simultaneously, starting a rotor of the shearing kettle, shearing at the rotating speed of 3000rpm until components in the ball milling kettle are transferred completely, and collecting a sample in the kettle to obtain the dry high-quality graphene.
The obtained graphene is used for preparing a graphene film, and the conductivity of the graphene film reaches 1.2 multiplied by 10 under the condition that the thickness of the graphene film is 12 mu m5S/m, compared with 2.8 multiplied by 10 of the raw material graphite3The conductivity of S/m is improved by two orders of magnitude, which shows that the prepared graphene has excellent electrical properties. Fig. 2 is an SEM picture of the obtained graphene, and it can be seen from the figure that the prepared graphene is semitransparent under SEM, the thickness is thin, the distribution is uniform, and the size of the sheet layer is 1-5 μm.
Example 2
20g of expanded graphite is added into a high-pressure stainless steel ball milling kettle with the volume of 1L, 600g of zirconia ball milling beads with the diameter of 1mm are added, and a kettle cover is screwed down. Controlling the temperature of the ball milling kettle to be 70 ℃, and pumping a certain amount of CO into the system by a high-pressure plunger pump2The air in the system is discharged, and then CO is continuously pumped in2Until the system pressure is 20 MPa. Opening the stirring paddle of the ball milling kettle, controlling the rotating speed of the stirring paddle to be 1000rpm, and performing supercritical CO2And performing ball milling treatment on the graphite raw material for 48 hours in the system. Opening an outlet valve of the ball milling kettle and a high-pressure plunger pump to control CO while not closing a stirring paddle of the ball milling kettle2The mass flow is 5kg/h, so that a sample in the ball milling kettle is subjected to continuous supercritical CO2And blowing the mixture into a high-pressure shearing kettle, simultaneously, starting a rotor of the shearing kettle, shearing at the rotating speed of 1500rpm until components in the ball milling kettle are transferred completely, and collecting a sample in the shearing kettle to obtain the dry high-quality graphene.
The obtained graphene is used for preparing a graphene film, and the conductivity of the graphene film reaches 1.5 multiplied by 10 under the condition that the thickness of the graphene film is 8 mu m5S/m shows that the prepared graphene has excellent electrical properties. Fig. 3 is a TEM image of the obtained graphene, and it can be seen from the image that the sample is semitransparent and the edge is curled, which indicates that the sample is very thin and the obtained graphene has high quality.
Example 3
Dispersing 100g of crystalline flake graphite in 200mL of ethanol, adding the dispersion into a high-pressure stainless steel ball milling kettle with the volume of 1L, simultaneously adding 1200g of alumina ball milling beads with the diameter of 10mm, and screwing down a kettle cover. Controlling the temperature of the ball milling kettle to be 60 ℃, and pumping a certain amount of CO into the system by a high-pressure plunger pump2The air in the system is discharged, and then CO is continuously pumped in2Until the system pressure is 25 MPa. Opening the stirring paddle of the ball milling kettle, controlling the rotating speed of the stirring paddle to be 2000rpm, and performing supercritical CO2And carrying out ball milling treatment on the graphite raw material in the system for 144 h. Opening an outlet valve of the ball milling kettle and a high-pressure plunger pump to control CO while not closing a stirring paddle of the ball milling kettle2The mass flow is 15kg/h, so that a sample in the ball milling kettle is subjected to continuous supercritical CO2Purging and entering a high-pressure shearing kettle, simultaneously, starting a rotor of the shearing kettle, shearing at the rotating speed of 2000rpm until components in the ball milling kettle are transferred completely, and collecting a sample in the shearing kettle by using ethanol to obtain a high-quality graphene ethanol dispersion liquid.
The obtained graphene is used for preparing a graphene film, and the conductivity of the graphene film reaches 1.1 multiplied by 10 under the condition that the thickness of the graphene film is 10 mu m5S/m shows that the prepared graphene has excellent electrical properties. Fig. 4 is a Raman spectrum of the obtained graphene, and it can be seen from the graph that the 2D peak position of the sample is located at 2690cm-1, and the symmetry is good, which indicates that the number of the obtained graphene layers is small. In the sample map ID/IGWhen the average molecular weight is 0.07, the obtained graphene has few defects and high quality.
Example 4
Adding 40g of natural graphite into a high-pressure stainless steel ball milling kettle with the volume of 1L, adding zirconium oxide ball milling beads mixed with different diameters, wherein the ball milling beads with the diameters of 1mm, 3mm, 5mm, 8mm and 10mm have the corresponding mass of 180g, 250g, 200g, 150g and 120g respectively, and screwing down a kettle cover. Controlling the temperature of the ball milling kettle to be 50 ℃, and pumping a certain amount of CO into the system by a high-pressure plunger pump2The air in the system is discharged, and then CO is continuously pumped in2Until the system pressure is 25 MPa. Opening the stirring paddle of the ball milling kettle, controlling the rotating speed of the stirring paddle to be 1500rpm, and performing supercritical CO2And performing ball milling treatment on the graphite raw material for 48 hours in the system. Opening an outlet valve of the ball milling kettle and a high-pressure plunger pump to control CO while not closing a stirring paddle of the ball milling kettle2The mass flow is 12kg/h, so that a sample in the ball milling kettle is subjected to continuous supercritical CO2And blowing the mixture into a shearing kettle, simultaneously starting a rotor of the shearing kettle, shearing the mixture at the rotating speed of 1000rpm until the components in the ball milling kettle are completely transferred, and collecting a sample in the kettle to obtain the dry high-quality graphene. The obtained graphene is used for preparing a graphene film, and the conductivity of the graphene film reaches 2.0 multiplied by 10 under the condition that the thickness of the graphene film is 15 mu m5S/m indicates that the prepared graphene is high in quality.
Example 5
Adding 80g of crystalline flake graphite into a high-pressure stainless steel ball milling kettle with the volume of 1L, adding stainless steel ball milling beads mixed with different diameters, wherein the corresponding masses of the ball milling beads with the diameters of 0.5mm, 1mm, 3mm, 5mm, 8mm, 10mm and 15mm are respectively 80g, 100g, 200g, 150g, 120g and 150g, and screwing a kettle cover. Controlling the temperature of the ball milling kettle to be 90 ℃, and pumping a certain amount of CO into the system by a high-pressure plunger pump2The air in the system is discharged, and then CO is continuously pumped in2Until the system pressure is 35 MPa. Opening the stirring paddle of the ball milling kettle, controlling the rotating speed of the stirring paddle to be 3000rpm, and performing supercritical CO2And carrying out ball milling treatment on the graphite raw material in the system for 300 h. Opening an outlet valve of the ball milling kettle and a high-pressure plunger pump to control CO while not closing a stirring paddle of the ball milling kettle2The mass flow is 25kg/h, so that a sample in the ball milling kettle is subjected to continuous supercritical CO2Blowing the mixture into a shearing kettle, and simultaneously opening the shearing kettle to rotateAnd shearing at the rotating speed of 3000rpm until the components in the ball milling kettle are completely transferred, and collecting a sample in the kettle to obtain the dry high-quality graphene. The obtained graphene is used for preparing a graphene film, and the conductivity of the graphene film reaches 1.4 multiplied by 10 under the condition that the thickness of the graphene film is 10 mu m5S/m indicates that the prepared graphene is high in quality.
Example 6
Adding 40g of expanded graphite into 50mL of ethanol to prepare a pasty raw material, adding the pasty raw material into a high-pressure stainless steel ball milling kettle with the volume of 1L, adding zirconium oxide ball milling beads mixed with different diameters, wherein the corresponding masses of the ball milling beads with the diameters of 0.1mm, 0.5mm, 1mm, 3mm and 5mm are respectively 100g, 200g, 250g, 150g and 150g, and screwing a kettle cover. Controlling the temperature of the ball milling kettle to be 60 ℃, and pumping a certain amount of CO into the system by a high-pressure plunger pump2The air in the system is discharged, and then CO is continuously pumped in2Until the system pressure is 25 MPa. Opening the stirring paddle of the ball milling kettle, controlling the rotating speed of the stirring paddle to be 2000rpm, and performing supercritical CO2And ball-milling the graphite raw material for 100 hours in the system. Opening an outlet valve of the ball milling kettle and a high-pressure plunger pump to control CO while not closing a stirring paddle of the ball milling kettle2The mass flow is 8kg/h, so that a sample in the ball milling kettle is subjected to continuous supercritical CO2And blowing the mixture into a shearing kettle, simultaneously, starting a rotor of the shearing kettle, shearing at the rotating speed of 500rpm until the components in the ball milling kettle are completely transferred, and collecting a sample in the kettle to obtain the dry high-quality graphene. The obtained graphene is used for preparing a graphene film, and the conductivity of the graphene film reaches 1.8 multiplied by 10 under the condition that the thickness of the graphene film is 7 mu m5S/m indicates that the prepared graphene is high in quality.
Comparative example 1:
compared with the embodiment 1, most of the graphite raw materials are the same, and the procedure of pretreating the graphite raw materials by a high-pressure ball milling kettle is omitted, namely, the raw material graphite is directly put into a high-pressure shearing kettle for shearing without pretreatment. And after the experiment is finished, collecting the sample in the shearing kettle to obtain a dry graphene product. Preparing the obtained graphene into a graphene film with the conductivity of 6.9 multiplied by 103S/m, the conductivity is much different from that of example 1, and is only slightly improved compared with the graphite raw material, because the supercritical state is not carried outCO2The graphite raw material particles subjected to ball milling pretreatment are large and difficult to enter the gap between the stator and the rotor of the shearing head, so that the stripping effect is poor.
Comparative example 2:
compared with the embodiment 1, most of the method is the same except that the high-pressure ball milling kettle is internally processed under normal pressure, namely, the raw material graphite is put into the high-pressure ball milling kettle, ball milling is carried out under normal pressure, and then CO is pumped into the high-pressure ball milling kettle2Carrying out supercritical CO2And (5) purging and shearing. And after the experiment is finished, collecting the sample in the shearing kettle to obtain a dry graphene product. Preparing a graphene film with a conductivity of 2.4 × 10 using the obtained graphene4S/m is smaller than that of example 1, which shows that the size of the graphite material can be reduced after the ball milling treatment under normal pressure, but the graphite material after pre-exfoliation is easy to be secondarily agglomerated, so that the subsequent exfoliation effect is not satisfactory.
Example 7:
compared with example 1, the most parts are the same, except that the ratio of the volume of the ball milling beads to the volume of the high pressure ball milling kettle is controlled to be 0.1 in this example, 300g of stainless steel ball milling beads with the diameter of 3mm are added. The test is carried out under the same condition, the graphene product in the shearing kettle is collected, filtered and formed into a film, the electrical property characterization is carried out, and the result shows that the conductivity of the obtained graphene product is 5.9 multiplied by 104And (5) S/m. The result is reduced compared with example 1, which is caused by the mass ratio of the stainless steel balls in the ball milling kettle to the graphite raw material is reduced, the mass transfer effect in the kettle is reduced, and the ball milling effect is weakened. 2.8X 10 times of graphite and raw material3Compared with the S/m conductivity, the conductivity of the obtained graphene product is still obviously improved, which shows that the method can be used for preparing high-quality graphene.
Example 8:
compared with example 1, the most parts are the same, except that the ratio of the volume of the ball milling beads to the volume of the autoclave in this example is controlled to be 0.8, i.e., 2400g of stainless steel balls with a diameter of 3mm are added. The test is carried out under the same condition, the graphene product in the shearing kettle is collected and filtered to form a film for electrical property characterization, and the result shows that the conductivity of the obtained graphene product is 9.2 multiplied by 104And (5) S/m. The result is still reduced compared with the embodiment 1, because on one hand, the mass ratio of the stainless steel ball milling beads in the ball milling kettle to the graphite raw material is increased, the mass transfer in the kettle is strengthened, the crushing effect of the ball milling beads on the raw material graphite is enhanced, and the stripping efficiency is improved; on the other hand, the pre-stripped graphite entering the high-pressure shearing kettle is reduced in size through crushing, so that the crosslinking degree of the graphene product in the prepared graphene film is reduced, and the electrical performance of the graphene film is affected. 2.8X 10 times of the phase of the raw material graphite3Compared with the conductivity of S/m, the conductivity of the obtained graphene product is still obviously improved, which indicates that the method is an effective method for preparing high-quality graphene.
Example 9:
compared with the embodiment 1, the method is mostly the same, except that the temperature in the high-pressure ball milling kettle is 33 ℃ in the embodiment; the pressure in the high-pressure ball milling kettle is 8 MPa; the rotating speed of a stirring paddle in the high-pressure ball milling kettle is 5000rpm, and the ball milling pretreatment time is 72 hours. Preparing a graphene film with a conductivity of 8.6 × 10 using the obtained graphene4The result is slightly lower than that of example 1 because the sheet size of the raw material graphite is sharply reduced at a higher ball milling rotation speed and a longer ball milling time, which results in a smaller sheet size of the obtained graphene after shear exfoliation and a lower degree of crosslinking in the graphene film. 2.8X 10 times of the phase of the raw material graphite3Compared with the S/m conductivity, the conductivity of the obtained graphene product is obviously improved, which shows that the method can be used for preparing high-quality graphene.
Example 10:
compared with the embodiment 1, the method is mostly the same, except that the temperature in the high-pressure ball milling kettle is 100 ℃; the pressure in the high-pressure ball milling kettle is 50 MPa; the rotating speed of a stirring paddle in the high-pressure ball milling kettle is 5000 rpm; the ball milling pretreatment time is 12 h. Preparing a graphene film with a conductivity of 2.1 × 10 using the obtained graphene5S/m, the result is improved compared to example 1, since at this temperature and pressure the supercritical CO is present2Has higher density than that of the condition of the example 1, thereby providing higher shear stress during the ball milling process; at the same time, the increase in pressure difference also causes the permeation of CO into the graphite layers2The number of molecules is increased, which is beneficial to weakening and stripping of Van der Waals force between graphite layers. 2.8X 10 times of the phase of the raw material graphite3Compared with the S/m conductivity, the conductivity of the obtained graphene product is obviously improved, which shows that the method can be used for preparing high-quality graphene.
Example 11:
compared with the embodiment 1, the method is mostly the same, except that the temperature in the high-pressure ball milling kettle is 40 ℃; the pressure in the high-pressure ball milling kettle is 12 MPa; the rotating speed of a stirring paddle in the high-pressure ball milling kettle is 600 rpm; the ball milling pretreatment time is 48 h. Preparing a graphene film with a conductivity of 2.7 × 10 using the obtained graphene5S/m, the result is improved compared to example 1, since at this temperature and pressure the supercritical CO is present2Has higher density than that of the condition of the example 1, thereby providing higher shear stress during the ball milling process; at the same time, the increase in pressure difference also causes the permeation of CO into the graphite layers2The number of molecules is increased, which is beneficial to weakening and stripping of Van der Waals force between graphite layers. In addition, the lower ball milling speed reduces the crushing effect on the graphite raw material, but due to the supercritical CO2The improvement of density makes up for a part of stripping effect, so that the thickness of the graphite sheet layer transferred into the shearing kettle is large, and the graphene product has higher electrical property.
Example 12:
compared with the embodiment 1, the method is mostly the same, except that the temperature in the high-pressure ball milling kettle is 65 ℃; the pressure in the high-pressure ball milling kettle is 25 MPa; the rotating speed of the stirring paddle in the high-pressure ball milling kettle is 2000 rpm; the ball milling pretreatment time is 24 h. Preparing a graphene film with a conductivity of 2.3 × 10 using the obtained graphene5S/m, the result is improved compared to example 1, the principle is similar to example 11, i.e. high CO2Density increased shear stress and CO2The penetration driving force is kept, and the large sheet size of the raw material graphite is kept at a low rotating speed, so that the electrical property of the product is excellent.
Example 13:
compared with example 1, most of them are the same except that in this example, control is performedProduction of CO2The flow rate of (2) was 5 kg/h. Preparing a graphene film with a conductivity of 1.5 × 10 using the obtained graphene5S/m, the result is slightly improved compared to example 1, due to the reduction of CO2After the flow is increased, the transfer rate of the pre-stripped graphite in the system is reduced, so that the retention time of the pre-stripped graphite in the high-pressure ball milling kettle is prolonged, the pre-stripping effect is improved, and the quality of the product graphene is improved.
Example 14:
compared with example 1, most of them are the same except that in this example, CO is controlled2The flow rate of (2) was 30 kg/h. Preparing a graphene film with a conductivity of 7.4 × 10 using the obtained graphene4S/m, the result being less than in example 1 due to the increased CO2After the flow rate is increased, the transfer rate of the pre-exfoliated graphite in the system is increased, so that the retention time of the pre-exfoliated graphite in the high-pressure ball milling kettle is reduced, and the pre-exfoliated effect is weakened, so that the conductivity of the product graphene is reduced compared with that in example 1. Compared with the raw material graphite of 2.8 multiplied by 103The conductivity of S/m and the conductivity of the graphene product obtained in the embodiment are still greatly improved, which shows that the method can still effectively strip graphite to prepare high-quality graphene.
Example 15:
compared with example 1, most of them are the same except that in this example, CO is controlled2The flow rate of (2) was 50 kg/h. Preparing a graphene film with a conductivity of 5.1 × 10 using the obtained graphene4S/m, the result is much different from the conductivity in example 1 due to the increase of CO2After the flow reaches 50kg/h, the graphite raw material in the high-pressure ball milling kettle is quickly transferred to the shearing kettle under the condition of not being effectively pre-stripped, and the thickness and the size of a sheet layer are difficult to adapt to the structures of a stator and a rotor of the shearing head, so that the pre-stripping effect is weakened, and the conductivity of the product graphene is greatly reduced compared with that in example 1. Compared with the raw material graphite of 2.8 multiplied by 103The conductivity of S/m and the conductivity of the graphene product obtained in the embodiment are still improved to a certain extent, which shows that under the limit condition, the method can still effectively strip graphite to prepare high-quality graphene.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims (10)

1. A novel method for preparing graphene on a large scale is characterized by comprising the following steps:
(1) putting graphite raw materials and ball milling beads into a high-pressure ball milling kettle, and passing through high-pressure CO2Pumping CO into the high-pressure ball milling kettle by a pump2Venting air to a set pressure to form supercritical CO2Performing ball milling pretreatment on the graphite raw material;
(2) keeping the ball mill open, and opening high-pressure CO2Pump, the graphite raw material pretreated in the high-pressure ball milling kettle is processed by supercritical CO2Purging and entering a high-pressure shearing kettle, simultaneously starting a shearing rotor in the high-pressure shearing kettle to perform shearing treatment, finishing the component transfer in the ball milling kettle, and collecting a product in the high-pressure shearing kettle to obtain high-quality graphene, namely a target product.
2. The novel method for mass production of graphene according to claim 1, wherein the graphite material is one or more of natural graphite, expanded graphite and flake graphite.
3. The novel method for mass production of graphene according to claim 1, wherein the graphite raw material is in the form of a dry raw material or a graphite dispersion liquid containing a solvent in the autoclave.
4. The novel method for mass production of graphene according to claim 1, wherein the volume ratio of the graphite raw material to the autoclave is controlled to be 10-100 g/L.
5. The novel method for preparing graphene on a large scale according to claim 1, wherein the ball milling beads are made of one or more of stainless steel, zirconia, alumina, agate, polyurethane-coated iron core and hard alloy; and the diameter of the ball milling beads is 0.1-20 mm.
6. The novel method for mass production of graphene according to claim 1, wherein the ratio of the volume of the ball milling beads to the volume of the autoclave is controlled to be 0.1-0.8: 1.
7. The novel method for preparing graphene in large batches according to claim 1, wherein during ball milling pretreatment, the temperature in a high-pressure ball milling kettle is 33-100 ℃, the pressure is 8-50 Mpa, the rotating speed is 300-5000 rpm, and the ball milling pretreatment time is 12-72 hours.
8. The novel method for mass production of graphene according to claim 1, wherein during the shearing treatment, the pressure in the high-pressure shearing kettle is 8-50 MPa, the temperature is 33-100 ℃, and the high-pressure shearing kettle is consistent with the ball milling kettle, the shearing speed is 500-4000rpm, and the shearing treatment time is 2-72 h.
9. The novel method for preparing graphene in large scale according to claim 1,the method is characterized in that CO is controlled in the process of transferring the pretreated graphite raw material from the high-pressure ball milling kettle to the high-pressure shearing kettle2The flow rate of (A) is 5-50 kg/h.
10. The novel method for mass production of graphene according to claim 1 or 9, wherein during the transfer of the pretreated graphite raw material from the autoclave to the autoclave, CO is generated2The graphite raw material taken out is intercepted in a high-pressure shearing kettle, and CO2Then high pressure CO is returned2The inlet of the pump is recycled.
CN202111435152.0A 2021-11-29 2021-11-29 Novel method for preparing graphene on large scale Pending CN113929089A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111435152.0A CN113929089A (en) 2021-11-29 2021-11-29 Novel method for preparing graphene on large scale

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111435152.0A CN113929089A (en) 2021-11-29 2021-11-29 Novel method for preparing graphene on large scale

Publications (1)

Publication Number Publication Date
CN113929089A true CN113929089A (en) 2022-01-14

Family

ID=79288646

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111435152.0A Pending CN113929089A (en) 2021-11-29 2021-11-29 Novel method for preparing graphene on large scale

Country Status (1)

Country Link
CN (1) CN113929089A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114672156A (en) * 2022-03-04 2022-06-28 上海交通大学 Preparation method of graphene/PA 6 composite material
CN114772585A (en) * 2022-03-04 2022-07-22 上海交通大学 Large-scale preparation method of graphene

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
HUIJUN TAN ET AL.: "Scalable massive production of defect-free few-layer graphene by ball-milling in series with shearing exfoliation in supercritical CO2", 《THE JOURNAL OF SUPERCRITICAL FLUIDS》 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114672156A (en) * 2022-03-04 2022-06-28 上海交通大学 Preparation method of graphene/PA 6 composite material
CN114772585A (en) * 2022-03-04 2022-07-22 上海交通大学 Large-scale preparation method of graphene
CN114772585B (en) * 2022-03-04 2023-11-17 上海交通大学 Large-scale preparation method of graphene

Similar Documents

Publication Publication Date Title
CN113929089A (en) Novel method for preparing graphene on large scale
US10717652B2 (en) Method for preparing large graphene sheets in large scale
CN105253878B (en) A kind of method that expanded graphite or graphene are directly prepared under normal temperature and pressure
EP3190085B1 (en) Method for preparing graphene by using high speed homogenization pretreatment and high pressure homogenization
CN110255548B (en) Method for preparing water-dispersible graphene slurry
CN114572972B (en) Apparatus and method for mass production of atomically thin two-dimensional materials including graphene
CN110578076A (en) Graphene nanosheet/aluminum composite material and preparation method thereof
CN110980707A (en) Method for preparing few-layer graphene through mechanical stripping and few-layer graphene
CN110627025A (en) Method for preparing two-dimensional graphite phase carbon nitride dispersion liquid by ultrasonic coupling supergravity rotating bed stripping
CN110040728B (en) Method and equipment for stripping layered material and size screening and separating two-dimensional nanosheet
CN112280248A (en) Cobalt ferrite/boron nitride/epoxy resin heat conduction material and preparation method thereof
CN111559743A (en) Preparation method and application of graphene powder
KR102097133B1 (en) Method for preparation of highly concentrated graphene dispersion
CN110255549B (en) Preparation method of graphene and stripping method of two-dimensional nano material
CN110759337A (en) Preparation method of graphene
CN210656168U (en) Equipment for producing thin graphene on large scale
CN111377438B (en) Graphene and preparation method thereof
CN114772585B (en) Large-scale preparation method of graphene
CN114425470A (en) Grinding disc device, graphene and preparation method of graphene
CN112694083A (en) Method for continuously producing graphene quantum dot slurry on large scale
CN111690848A (en) Preparation method and application of low-thermal-expansion-rate aluminum alloy composite material
CN110562966A (en) Preparation process of charged tetrafluoroethylene-hexafluoropropylene polymer-containing graphene powder
CN110550622B (en) By using supercritical CO2Method for preparing graphene by auxiliary liquid phase stripping
CN115465860B (en) Preparation method of low-oxygen and high-stripping graphene oxide and application of obtained product
KR102670710B1 (en) The method of refineing wasteed graphite

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination