CN114425470A

CN114425470A - Grinding disc device, graphene and preparation method of graphene

Info

Publication number: CN114425470A
Application number: CN202011091971.3A
Authority: CN
Inventors: 王湘; 戚桂村; 曾宪忠; 陈翔; 姜超; 李秉海; 宋志海; 茹越; 张江茹; 赵月云; 张晓红
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2020-10-13
Filing date: 2020-10-13
Publication date: 2022-05-03
Anticipated expiration: 2040-10-13
Also published as: CN114425470B

Abstract

The invention discloses a grinding disc device, graphene and a preparation method of the graphene. The mill device including have air inlet and discharge gate the internal portion of cauldron sets up mill part and is used for driving mill part pivoted rotating member, mill part is including the last mill that is provided with the feed inlet, lower mill, set up in the stirring rake of mill below down and be used for making the material flow in the baffle of feed inlet. The grinding disc device is simple, the applicable reaction range is wide, the temperature and the pressure are controllable, and the material grinding disc enters between the two grinding discs from the upper part of the grinding disc in a high-speed rotating mode, so that the high-quality graphene is prepared.

Description

Grinding disc device, graphene and preparation method of graphene

Technical Field

The invention relates to a grinding disc device, graphene and a preparation method of the graphene.

Background

At present, the main methods for preparing graphene include a redox method, a liquid phase exfoliation method, a vapor deposition method, and the like. The oxidation-reduction method is the most common method at present and is the most industrialized at present, but the graphene prepared by oxidation of the strong oxidant has many defects, so that the physical and chemical properties of the graphene are still lost even after reduction, and a large amount of strong oxidant, acid and other chemical reagents are used in the preparation process, so that the environmental pollution is serious. The liquid phase stripping method mainly adopts ultrasonic stripping, namely ultrasonic stripping in an organic solvent for a long time, so that the prepared graphene has few defects, but the use of the organic solvent has harm to a human body, and the problems of low yield, small size of the prepared graphene and the like exist. The vapor deposition (CVD) method uses a carbon-containing compound such as methane as a raw material, and graphene is grown by pyrolysis on the surface of a substrate such as a metal. This is the main method for preparing graphene thin films at present. However, the CVD process is not mature and has high cost, which limits its large-scale application. Therefore, preparing graphene is still an important point in the field of graphene research.

CN105800594B discloses a graphene material based on a solid-phase mechanochemical reactor and a preparation method thereof. A grinding aid is introduced in the process of grinding graphite by utilizing a three-dimensional strong shearing structure of a solid-phase mechanochemical reactor, and the grinding aid and the graphite generate strong mutual friction action through three-dimensional shearing force caused by the three-dimensional shearing structure to strip the graphite, so that single-layer or few-layer graphene is prepared.

CN106044761B discloses a high-shear-force wear-resistant rubber grinding disc for preparing graphene, and a preparation method and application thereof. The friction force of the upper grinding disc and the lower grinding disc of the wear-resistant rubber is large, the graphite stripping efficiency is high, the thickness of the obtained graphene is thin, the upper grinding disc and the lower grinding disc of the wear-resistant rubber are mainly pure shear force, the impact force is small, the damage to graphite lattices can be effectively avoided, the structural defects of the graphene are reduced, and the quality of the prepared graphene is high. However, these devices are not self-recycling and are not closed systems, which are not suitable for applications where volatile substances are generated or where certain temperatures and pressures are required.

CN109382167A discloses a self-circulating grinding disc device for use in high pressure environment. Specifically, self-loopa mill dress includes first casing and sets up the inside self-loopa mill reaction unit of first casing, self-loopa mill reaction unit includes top fastening connection the mill back-up on the inner wall of first casing top, the first mill of bottom fastening connection of mill back-up the top of first mill is provided with the second mill, the bottom of second mill with the top of first mill is mutual disposition the bottom of second mill is provided with and is used for discharging the water conservancy diversion portion of first mill with material between the second mill, the centrifugal force of second mill makes first mill with form vacuum negative pressure region between the second mill. However, the device needs a vacuum negative pressure area formed between the first grinding disc and the second grinding disc, materials are sucked between the first grinding disc and the second grinding disc from bottom to top, material flow is not easy to enter between the two grinding discs, and the grinding efficiency is low.

CN110817853A discloses a preparation method of edge carboxylated graphene. Specifically, the preparation method of graphene comprises step S1, adding purified or unpurified graphite powder into a high-pressure grinding disc kettle; step S2, introducing carbon dioxide into the high-pressure grinding disc kettle, and enabling the carbon dioxide to be in a supercritical state to form a material containing graphite powder and supercritical carbon dioxide; and step S3, grinding the material containing the graphite powder and the supercritical carbon dioxide.

The grinding disc adopted by the prior art can directly realize the effects of shearing and stripping at the same time, but the efficiency of the grinding disc is too low, and the ratio of graphene products with the number of layers below 10 needs to be improved.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a novel grinding disc device which is simple, wide in application reaction range and controllable in temperature and pressure, and materials enter between two grinding discs from the upper parts of the grinding discs by means of gravity and high-speed rotation of the grinding discs, so that high-quality graphene is prepared.

In the present invention, the use of directional terms such as "upper, lower, left, right, top, side" in the absence of a contrary indication generally means upper, lower, left, right, top, side as viewed in the drawings; "inner and outer" refer to the inner and outer relative to the profile of the components themselves.

The invention provides a grinding disc device which comprises a sealing kettle body with an air inlet and a discharge hole, a grinding disc component and a rotating component, wherein the grinding disc component and the rotating component are arranged in the kettle body and used for driving the grinding disc component to rotate, and the grinding disc component comprises an upper grinding disc with a feed inlet, a lower grinding disc, a stirring paddle arranged below the lower grinding disc and a baffle plate used for enabling materials to flow into the feed inlet.

In the present invention, material flows from the feed inlet into the interior of the grinding disc member.

In the invention, the stirring paddle below the lower grinding disc is used for stirring materials, so that the material flow can enter from the feeding hole to flow into the inner part of the grinding disc component, and the grinding is carried out.

In the invention, the baffle plate can be arranged on the side wall of the grinding disc component and is used for enabling the materials to flow into the feeding hole. Due to the action of the baffle plate, materials can more easily enter the feeding hole in the grinding disc component and then enter the space between the upper grinding disc and the lower grinding disc.

According to some embodiments of the millstone assembly of the invention, the kettle body has a jacket and/or a top kettle cover.

According to some embodiments of the grinding disc arrangement of the present invention, the upper grinding disc is placed above the lower grinding disc by its own weight.

According to some embodiments of the grinding disc arrangement of the present invention, the upper grinding disc is provided with flow guiding grooves.

According to some embodiments of the grinding disc device of the present invention, the lower grinding disc is connected to a rotating member, and the rotation of the lower grinding disc is controlled by the rotating member.

According to some embodiments of the abrasive disc device of the present invention, the lower abrasive disc has grooves, and more preferably, the pattern of the grooves is selected from at least one of a mortar type (e.g., as shown in fig. 6), a chrysanthemum type, and a fan type.

According to some embodiments of the grinding disc device, the grinding disc component further comprises a grinding disc support fixed on the top of the kettle body and used for limiting the upper grinding disc.

According to some embodiments of the grinding disc device, a gap adjusting bolt is further installed between the upper grinding disc and the lower grinding disc and used for adjusting the gap between the upper grinding disc and the lower grinding disc.

According to some embodiments of the abrasive disc device of the present invention, the rotating member is a magnetic rotating member.

The second aspect of the present invention provides graphene having a carboxyl-modified group, wherein the number of graphene layers is 10 or less, and the ratio of the number of graphene layers is not less than 30%.

According to some embodiments of the graphene of the present invention, the ratio of the number of layers of the graphene to 10 layers or less is 30 to 50%.

In the present invention, the statistical method for the ratio of the number of graphene layers to 10 layers or less may be: taking a TEM image of 100 pieces of graphene, the graphene is counted as a ratio of the number of 10 layers or less. For example, a TEM image of 100 pieces of graphene is taken, and in 90 TEM images, 10 or less layers of graphene are all present, i.e., the ratio of the number of graphene layers to 10 or less is 90%.

According to some embodiments of the graphene of the present invention, the graphene is prepared by a mechanical exfoliation method using the abrasive disc device of the present invention.

According to some embodiments of the graphene of the present invention, the graphene has an elemental oxygen content of no greater than 10%. The oxygen element can be measured by XPS equipment.

According to some embodiments of the graphene of the present invention, the graphene has an electrical conductivity of 500 to 1000S/m. Conductivity can be measured by a powder resistivity conductivity tester.

According to some embodiments of the graphene of the present invention, the graphene has a micron-scale sheet size, and more preferably, the sheet size of the graphene is 1 to 20 microns.

According to a third aspect of the present invention, a graphene preparation method is provided, including mixing graphite powder and supercritical carbon dioxide by using the above grinding disc device, and grinding.

According to some embodiments of the method of preparing of the present invention, the graphite powder is flake graphite powder and/or expanded graphite powder.

According to some embodiments of the preparation method of the present invention, the graphite powder has a particle size of 10 to 80 mesh, preferably 20 to 60 mesh.

According to some embodiments of the process of the present invention, the supercritical carbon dioxide has a temperature greater than 31.26 ℃ and a pressure greater than 7.29 MPa.

According to some embodiments of the preparation method according to the present invention, the weight ratio of graphite powder to carbon dioxide is 1:5 to 1:40, preferably 1:5 to 1: 25.

According to some embodiments of the method of making described herein, the rotational speed of the grinding disc in the tank is 500 to 3000 r/min.

According to some embodiments of the preparation method of the present invention, the temperature in the tank is 35 to 200 ℃, preferably 35 to 100 ℃, and more preferably 34 to 70 ℃.

According to some embodiments of the preparation method of the present invention, the pressure in the tank is 75 to 300atm, preferably 75 to 200atm, more preferably 75 to 160 atm.

In the present invention, the pressure in the tank means a pressure under gauge pressure.

According to some embodiments of the method of manufacturing of the present invention, after the grinding, the method further comprises depressurizing to atmospheric pressure within 5-20 s.

According to some embodiments of the preparation method of the present invention, the preparation method of graphene may include the steps of:

step 1, adding purified or unpurified graphite powder into a kettle;

step 2, introducing carbon dioxide into a kettle, controlling the temperature and the pressure, enabling the carbon dioxide to be in a supercritical state, forming a mixture of graphite powder and supercritical carbon dioxide, and grinding the mixture in the kettle;

and 3, grinding for a certain time, and then quickly reducing the pressure in the kettle to normal pressure to obtain the graphene product.

In a fourth aspect, the present invention provides graphene prepared by the above method.

According to some embodiments of the graphene of the present invention, the graphene has a carboxyl modification group, and the number of layers of the graphene is 10 or less at a ratio of not less than 30%.

According to some embodiments of the graphene of the present invention, the ratio of the number of layers of the graphene being 10 or less is 30 to 50%

According to some embodiments of the graphene of the present invention, the graphene has an elemental oxygen content of no greater than 10%.

According to some embodiments of the graphene of the present invention, the graphene has an electrical conductivity of 500 to 1000S/m.

The invention has the beneficial effects that:

(1) the grinding disc component of the device is provided with the feed inlet through which materials flow into the grinding disc component, and the materials can be sucked into the grinding disc through the high-speed rotation of the grinding disc, so that the efficiency of the grinding disc can be improved.

(2) The grinding disc device comprises the stirring paddle and the baffle plate, and the stirring paddle and the baffle plate are beneficial to mixing of materials, so that the efficiency of the materials entering the grinding disc is further improved.

(3) The grinding disc device is simple in structure and convenient to use.

(4) The graphene of the present invention has a carboxyl-modified group, and the ratio of the number of graphene layers is 10 or less is not less than 30%.

(5) The preparation method of the invention adopts supercritical carbon dioxide as solvent, and the process is green and environment-friendly without post-treatment.

Drawings

Fig. 1 is a schematic structural diagram of a grinding disc device provided in embodiment 1 of the present invention;

FIG. 2 is a schematic view of an upper grinding disc provided in embodiment 1 of the present invention;

FIG. 3 is a schematic view of a lower grinding disc provided in embodiment 1 of the present invention;

fig. 4 is an SEM image of graphene provided in example 2 of the present invention;

FIG. 5 is a TEM image of graphene provided in example 2 of the present invention;

FIG. 6 is a schematic view of a mortar type.

Drawings

1. A kettle body; 11. a jacket; 12. a kettle cover; 13. an air inlet; 14. a discharge port; 15. a feed inlet; 2. a magnetic force rotating member; 3. grinding disc components, 31 and an upper grinding disc; 32. a lower grinding disc and 33 stirring paddles; 34. a gap adjusting bolt; 35. a baffle plate; 36. the mill support.

Detailed Description

In order that the present invention may be more readily understood, the following detailed description of the invention is given by way of example only, and is not intended to limit the scope of the invention.

The test method and the equipment used in the test are as follows:

(1) SEM (scanning Electron microscope) was purchased from FEI Inc. under model number XL-30.

(2) TEM (Transmission Electron microscope) was purchased from Philips under the model number TECNAL 20.

(4) The oxygen content was measured using XPS equipment from Thermo Fisher Scientific under the model ESCALB 250.

(5) The electrical conductivity was measured using a powder resistivity conductivity tester, model FT-300, available from Ningbo Rui Wei instruments Inc.

[ example 1 ]

The grinding disc device shown in fig. 1 is adopted, and the device comprises a kettle body 1, a magnetic transmission component 2 and a grinding disc component 3. The grinding disc component 3 is provided with a material inlet 15 for material to flow into the grinding disc component. Wherein the kettle body 1 also comprises a jacket 11 and a top kettle cover 12, and the kettle body can be sealed. The kettle cover is provided with an air inlet 13 for the air inlet and the air outlet of gas materials or protective gas; a discharge hole 14 is arranged below the kettle body, so that solid or liquid materials can be discharged conveniently; the kettle cover 12 is connected with flanges at the upper end and the lower end of the kettle body 1 through studs, and high-pressure sealing is realized by means of O-shaped rings; the transmission shaft is driven by the magnetic transmission part to rotate clockwise at a high speed so as to drive the lower grinding disc 32 and the stirring paddle 33 to move in the same direction; two ends of the grinding disc bracket 36 are respectively fixed on the kettle cover 12 and the upper grinding disc 31 and used for limiting the upper grinding disc, and the gap between the upper grinding disc 31 and the lower grinding disc 32 is adjusted through the gap adjusting bolt 34. The grinding disc component also comprises a baffle 35 arranged on the side wall of the grinding disc component, and the baffle 35 is fixed in the groove of the upper grinding disc. The upper grinding disc is provided with guide grooves, and the figure of the upper grinding disc is schematically shown in figure 2. The lower grinding disc is provided with grooves, the patterns of the grooves are fan-shaped, and the figure of the lower grinding disc is schematically shown in figure 3.

The working process of the device is as follows:

the gap between the upper grinding disc 31 and the lower grinding disc 32 is adjusted by the gap adjusting bolt 34. Then, graphite powder materials are directly placed in the kettle body, and the kettle cover 12 and the kettle body 1 are connected in a sealing mode through the studs and the flanges at the upper end and the lower end of the kettle body. Gaseous materials are injected into the kettle through the gas inlet 13. The temperature in the jacket 11 is controlled by a circulating heating pump outside the kettle. Then the rotational speed is set and the magnetic rotation element 2 is turned on. The lower grinding disc 32 and the stirring paddle 33 rotate along with the lower grinding disc, and materials flow in the kettle body 1 and enter between the upper grinding disc 31 and the lower grinding disc 32 from the feeding hole 15. Due to the baffle 35, the material can enter between the upper grinding disc 31 and the lower grinding disc 32 more easily.

[ example 2 ]

This example provides a method of preparing graphene using the abrasive disc apparatus of example 1.

The gap between the upper and lower grinding discs was adjusted to 1 mm by gap adjusting bolts, and then 100g of 32 mesh flake graphite powder (available from Qingdao gold Tao graphite Co., Ltd.) was placed in the pot. The kettle cover is connected and sealed with the upper end flange and the lower end flange of the kettle body through studs. 2.5kg of carbon dioxide is injected into the kettle through the air inlet, and the pressure in the kettle is 60 atm. The temperature in the vessel was set to 55 ℃ by means of a jacket. Then the rotation speed of the grinding disc is set to 1000rpm, and the magnetic rotating part is started. The pressure in the kettle rises to 120 atm. After 24h, the experiment was stopped. And opening the air inlet, reducing the pressure in the kettle to 1atm within 10s, and discharging the material from a discharge hole 14 below the kettle body to obtain the graphene.

The obtained graphene was analyzed by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), and the results are shown in fig. 4 and 5, where the graphene sheet diameter is 10 to 20 μm. The number of layers was counted to obtain a rate of 10 layers of the graphene obtained in example 2 of 36%. The conductivity of the graphene is 870S/m, and the content of oxygen element is 5.3%.

[ example 3 ]

The gap between the upper grinding disc and the lower grinding disc is adjusted to 3 mm by a gap adjusting bolt, and then 50g of 32-mesh expanded graphite powder is placed in the kettle body. The kettle cover is connected and sealed with the upper end flange and the lower end flange of the kettle body through studs. 2.5kg of carbon dioxide is injected into the kettle through the air inlet, and the pressure in the kettle is 60 atm. The temperature in the kettle was set to 70 ℃ by jacket addition. Then the rotational speed of the grinding disc is set to 2000rpm, and the magnetic rotating part is started. The pressure in the kettle rises to 160 atm. After 48h, the experiment was stopped. And opening the air inlet, reducing the pressure in the kettle to 1atm within 10s, and discharging the material from a discharge hole 14 below the kettle body to obtain the graphene.

And analyzing the prepared graphene by using a Scanning Electron Microscope (SEM) and a Transmission Electron Microscope (TEM), wherein the diameter of the graphene sheet is 5-10 micrometers. The number of layers was counted to obtain a ratio of 10 layers of the graphene obtained in example 3 of about 41%. And the conductivity of the graphene is determined to be 530S/m, and the content of oxygen element is 7.8%.

Comparative example 1

Adopt CN109382167A description paragraph [ 0034 ] to [ 0048 ] for the self-loopa mill device under high pressure environment. 100g of 32-mesh flake graphite powder is placed in a kettle body. 2.5kg of carbon dioxide is injected into the kettle through the air inlet, and the pressure in the kettle is 60 atm. The temperature in the vessel was set to 55 ℃ by means of a jacket. Then the rotation speed of the grinding disc is set to 1000rpm, and the magnetic rotating part is started. The pressure in the kettle rises to 120 atm. After 24h, the experiment was stopped. And opening the air inlet, reducing the pressure in the kettle to 1atm within 10s, and discharging the material from a discharge hole 14 below the kettle body to obtain the graphene.

And analyzing the prepared graphene by using a Scanning Electron Microscope (SEM) and a Transmission Electron Microscope (TEM), wherein the diameter of the graphene sheet is 5-10 micrometers. The number of layers of the graphene prepared in comparative example 1 was counted to obtain a ratio of 10 layers of about 13%, an electrical conductivity of 87S/m, and an oxygen content of 13.4%.

Comparative example 2

According to the grinding disc device of the embodiment 1, except that the baffle 35 is not provided.

Graphene was prepared according to the starting materials and methods of example 2.

And analyzing the prepared graphene by using a Scanning Electron Microscope (SEM) and a Transmission Electron Microscope (TEM), wherein the diameter of the graphene sheet is 10-50 micrometers. The number of layers of the graphene prepared in comparative example 2 was counted to obtain a ratio of 10 layers of about 15%. The electric conductivity of the graphene is 1200S/m, and the content of oxygen element is 2.9%.

Comparative example 3

According to the millstone arrangement of example 1, except that no stirring paddle 33 is provided.

The prepared graphene is analyzed by a Scanning Electron Microscope (SEM) and a Transmission Electron Microscope (TEM), and the graphene sheet diameter is larger than 100 micrometers. The number of layers of the graphene prepared in comparative example 3 was counted to obtain a ratio of 10 layers of about 0%. The conductivity of the graphene is 1800S/m, and the content of oxygen is 0%.

What has been described above is merely a preferred example of the present invention. It should be noted that other equivalent variations and modifications can be made by those skilled in the art based on the technical teaching provided by the present invention, and the protection scope of the present invention should be considered.

Claims

1. The utility model provides a mill device, including the sealed cauldron body that has air inlet and discharge gate the internal portion of cauldron sets up mill part and is used for driving mill part pivoted rotating member, mill part is including the runner stone, the lower mill that are provided with the feed inlet, set up in the stirring rake of lower mill below and be used for making the material flow in the baffle of feed inlet.

2. The millstone assembly of claim 1, wherein the kettle body has a jacket and/or a top kettle cover.

3. The grinding disc device according to claim 1 or 2, characterized in that the upper grinding disc is provided with flow guiding grooves; and/or the presence of a gas in the gas,

the lower grinding disc is provided with grooves, and more preferably, the patterns of the grooves are selected from at least one of mortar type, chrysanthemum type and fan shape; and/or the presence of a gas in the gas,

the grinding disc component also comprises a grinding disc support fixed at the top of the kettle body and used for limiting an upper grinding disc; and/or the presence of a gas in the gas,

and a gap adjusting bolt is further arranged between the upper grinding disc and the lower grinding disc and used for adjusting the gap between the upper grinding disc and the lower grinding disc.

4. The abrasive disc device of any one of claims 1-3 wherein said rotating member is magnetically rotated.

5. Graphene having a carboxyl-modified group, wherein the number of graphene layers is 10 or less, and the ratio is not less than 30%, preferably 30 to 50%.

6. The graphene of claim 5, wherein the graphene has an elemental oxygen content of no greater than 10%; and/or the presence of a gas in the gas,

the conductivity of the graphene is 500-1000S/m; and/or the presence of a gas in the gas,

the graphene has a micron-scale sheet diameter, and more preferably, the sheet diameter of the graphene is 1-20 microns.

7. A preparation method of graphene, which comprises the step of mixing and grinding graphite powder and supercritical carbon dioxide by using the grinding disc device as claimed in any one of claims 1 to 4.

8. The preparation method according to claim 7, characterized in that the graphite powder is selected from the group consisting of flake graphite powder and expanded graphite powder, preferably the particle size of the graphite powder is 10-80 mesh, preferably 20-60 mesh; and/or the presence of a gas in the gas,

the weight ratio of graphite powder to carbon dioxide is 1:5-1:40, preferably 1:5-1: 25.

9. The preparation method according to claim 7 or 8, wherein the rotation speed of the grinding disc in the kettle is 500-3000 r/min; and/or the presence of a gas in the gas,

the temperature in the kettle is 35-200 ℃, preferably 35-100 ℃, and more preferably 34-70 ℃; and/or the presence of a gas in the gas,

the pressure in the tank is 75 to 300atm, preferably 75 to 200atm, more preferably 75 to 160 atm.

10. Graphene prepared by the method of any one of claims 7-9.