WO2018157481A1

WO2018157481A1 - Nano graphene and preparation method therefor

Info

Publication number: WO2018157481A1
Application number: PCT/CN2017/085560
Authority: WO
Inventors: 曾济天
Original assignee: 曾济天
Priority date: 2017-03-03
Filing date: 2017-05-23
Publication date: 2018-09-07
Also published as: CN108529602A

Abstract

Provided are nano graphene and a preparation method therefor, relating to the technical field of materials. The method comprises: mixing graphite powder and water, and grinding to obtain slurry; and then using water or liquid carbon dioxide as an extraction agent to extract the slurry, filtering to obtain a filtrate, and drying. The method is easy to operate, has low energy consumption, low costs and high efficiency, and can quickly prepare a high-quality nano graphene material in large batch. Also provided is nano graphene prepared by the method. The nano graphene has low costs and is widely applicable.

Description

Nano graphene and preparation method thereof

Cross-reference to related applications

The present application claims priority to Chinese Patent Application No. CN201710123448.6, entitled "A Nano Graphene and Its Preparation Method", filed on March 3, 2017, the entire contents of which are incorporated herein by reference. In this application.

Technical field

The invention relates to the technical field of materials, and in particular to a nano graphene and a preparation method thereof.

Background technique

Graphene is currently the hardest and thinnest material in the world, and it also has strong toughness and electrical conductivity. These extremely special features make it a huge development space. Since the discovery of graphene, research on graphene has made important progress, and it has shown many exhilarating achievements in the fields of electronics, aerospace, optics, energy storage, biomedicine, quantum physics, materials, chemistry, daily life, etc. Performance and potential application prospects. At the same time, a large number of structurally intact high quality graphene materials are needed. This requires an increase in the level of existing manufacturing processes to achieve large scale, low cost, controlled synthesis and preparation.

At present, the preparation methods of graphene can be generally divided into two types: physical methods and chemical methods. The physical method is obtained from graphite or similar materials with high lattice completeness, and the obtained graphene scale is above 80 nm. The chemical method is prepared by small molecule synthesis or solution separation, and the scale of graphene is below 10 nm. Physical methods include: mechanical peeling method, orientation epitaxy method; chemical methods include: arc method, chemical vapor deposition method, solution chemical method (graphite reduction method). These production methods are complicated, immature, limited in application, small in size, and high in cost, which are not conducive to industrial production.

Summary of the invention

The object of the present invention is to provide a method for preparing nano graphene, which is simple in operation, low in energy consumption, low in cost and high in efficiency, and can rapidly prepare high-quality nano graphene materials in large quantities.

Another object of the present invention is to provide a nanographene which is obtained by the above method and has stable properties and is widely used.

The technical problem solved by the present invention is achieved by the following technical solutions.

The invention provides a preparation method of nano graphene, comprising:

The graphite powder is mixed with water and refined to obtain a slurry.

The slurry is extracted with water or liquid carbon dioxide as an extractant, filtered, and the filtrate is obtained and dried.

The present invention proposes a nanographene produced by the above preparation method.

The nano graphene provided by the preferred embodiment of the present invention and the preparation method thereof have the beneficial effects of using water or liquid carbon dioxide as an extracting agent to prevent the extractant from reacting with the graphite powder during the extraction process, reducing the production efficiency and affecting the obtained nanometer. Compared with the traditional production methods, the properties of graphene change the process complexity, low yield, serious environmental pollution, etc. during the processing of nanographene, optimize the process flow and reduce the production cost. It can quickly realize large-scale industrial production.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in order to clarify the objects, the technical solutions and the advantages of the embodiments of the present invention. Those who do not specify the specific conditions in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are conventional products that can be obtained by commercially available purchase.

A nano graphene and a preparation method thereof according to embodiments of the present invention are specifically described below.

A method for preparing nano graphene comprises:

The graphite powder is mixed with water and refined to obtain a slurry. The slurry is extracted with water or liquid carbon dioxide as an extractant, filtered, and the filtrate is obtained and dried.

Specifically, the graphite powder is preferably a graphite powder having a fixed carbon content of 50 to 99.9% and a particle diameter of less than 500 mesh, which facilitates subsequent grinding. The graphite powder described herein is a natural, non-oxidized graphite powder.

Preferably, the ratio of dry weight to wet weight ratio of the graphite powder is 1..1-2, and the dry-wet ratio refers to the weight ratio of the graphite powder to the weight of the wet graphite after soaking and filtering the residual water. Under the condition of this ratio, the grinding efficiency is improved to prevent the waste of water resources.

The refining described herein is preferably milled by a colloid mill or a cone mill, and the milling efficiency is high. Specifically, the particle size of the refining graphite powder is preferably 5-30 micrometers, which facilitates subsequent extraction and improves extraction. The efficiency of the graphite powder is accelerated, and the particle size of the graphite powder after refining can be specifically limited by filtration, and will not be described here. In other examples of the present invention, the graphite powder in the slurry obtained by refining may have a particle diameter of 9 to 27 μm, or 12 to 20 μm, or 16 to 19 μm.

In order to ensure that the graphite powder after refining does not chemically react with the extracting agent during the extraction process, preferably, the slurry is extracted by using water or liquid carbon dioxide as an extracting agent, and the chemical properties of the two are stable and can be effectively used in the extraction process. Prevents reaction with graphite powder and extracted nanographene while preventing graphite powder and extracted nanographene from being oxidized. In the embodiment of the present invention, water or liquid carbon dioxide is used as an extracting agent. Generally, the extracting agent is an inert substance with respect to graphite powder and graphene, that is, the extracting agent does not adversely affect graphite powder and graphene, for example, extraction. The agent does not oxidize graphite powder and does not oxidize graphene.

Preferably, the dissociation is carried out under at least one of supercritical extraction, microwave extraction, ultrasonic extraction, ultrahigh pressure extraction and nano-abrasive extraction, which can effectively improve the efficiency of dissociation of graphite powder into nano graphene and shorten the nano graphene. The production cycle reduces its production costs.

Specifically, when the extraction is supercritical extraction, the pressure is 25-80 MPa, the power is 5-25 Kw, 0 ° C < temperature ≤ 40 ° C, the extraction efficiency is improved, and more preferably, under the above conditions, when the flow rate At 1000-2000 L/h, supercritical extraction is carried out for 45-60 min, during which the graphite powder is sufficiently dissociated into nanographene. In other examples of the invention, the conditions for supercritical extraction are a pressure of 30-76 MPa, a power of 9-20 KW, a flow rate of 0 ° C < temperature ≤ 30 ° C, and a flow rate of 1100-1800 L/h; or a pressure of 37-55 MPa. Force, 13-19KW power, 10 °C < temperature ≤ 26 ° C, 1200-1700 L / h flow; or, 41-49MPa pressure, 15-20KW power, 12 ° C < temperature ≤ 17 ° C, 1400-1500L / h traffic.

Specifically, when the extraction is microwave extraction, the extraction is performed under the conditions of a frequency of 300-915 MHz, a power of 5-25 Kw, and a temperature of 0 ° C < temperature ≤ 40 ° C; more preferably, under the above conditions, when the reaction volume When it is 1000-3000L, extraction is carried out for 45-60 minutes, and the graphite powder is sufficiently dissociated into nano graphene. The reaction volume described herein is the mixed volume of the extractant, the slurry, or the mixed volume of the extractant, the slurry, and other additives added, and the other additives described herein are surface modifiers and solvents. In other examples of the invention, the conditions for microwave extraction are: a frequency of 370-900 MHz, a power of 5-20 KW, a temperature of 10 ° C < temperature ≤ 30 ° C; or a frequency of 426-875 MHz, a power of 8-17 KW, 7 ° C <temperature ≤ 23 ° C; or, frequency of 300-500 MHz, power of 5-25 KW, 9 ° C < temperature ≤ 18 ° C.

Specifically, when the extraction is ultrasonic extraction, the extraction is carried out under the conditions of a frequency of 20-50 KHz, a power of 5-25 Kw, and a temperature of 0 ° C < temperature ≤ 40 ° C; more preferably, under the above conditions, when the reaction volume When it is 1000-3000L, extraction is carried out for 45-60 minutes, and the graphite powder is sufficiently dissociated into nano graphene. In other examples of the invention, the conditions for ultrasonic extraction are a frequency of 20-40 KHz, a power of 5-20 KW, a temperature of 9 ° C < temperature ≤ 36 ° C; or a frequency of 25-42 KHz, a power of 9-10 KW, 15 ° C < Temperature ≤ 30 ° C; or, 30-43 KHz frequency, 15-22 KW power, 7 ° C < temperature ≤ 20 ° C.

Specifically, when the extraction is ultrahigh pressure extraction, the pressure is 250-380 MPa, the power is 5-25 Kw, and 0 ° C < temperature ≤ 40 ° C, the extraction efficiency is improved, and more preferably, under the above conditions, when the flow rate is When it is 1000-2000 L/h, the overpressure is 2-5 min, and the graphite powder is sufficiently dissociated into nano graphene. In other examples of the invention, the conditions for ultrahigh pressure extraction are a pressure of 250-350 MPa, a power of 5-20 KW, a flow rate of 11 ° C < temperature ≤ 40 ° C, 1200-1800 L/h; or a pressure of 270-300 MPa, 10-23KW power, 15 °C < temperature ≤ 30 ° C, 1300-1600 L / h flow; or, 300-380 MPa pressure, 5-13 KW power, 20 ° C < temperature ≤ 28 ° C, 1000-1500 L / h flow.

Specifically, when the extraction is nano-abrasive extraction, the pressure is 50-80 MPa, the power is 5-25 KW, 0 ° C < temperature ≤ 40 ° C, the extraction efficiency is improved, and more preferably, under the above conditions, when the flow rate is Overpressure is carried out for 2-5 min under conditions of 1000-5000 L/h or a reaction volume of 100-500 L to sufficiently dissociate the graphite powder into nanographene. In other examples of the present invention, the conditions of the nano-abrasive extraction are: a pressure of 50-70 MPa, a power of 16-25 KW, a flow rate of 16 ° C < temperature ≤ 30 ° C, and a flow rate of 1700-4000 L/h; Or, 70-80 MPa pressure, 5-15 KW power, 10 ° C < temperature ≤ 29 ° C, 1000-3000 L / h flow; or, 50-77 MPa pressure, 8-20 KW power, 9 ° C < temperature ≤ 19 °C, flow rate of 2000-3000L/h.

Preferably, it is also possible to carry out combined extraction using two or more of the above extraction methods under the preferred parameter conditions of each of the above extraction methods, thereby optimally optimizing the coordination scheme by controlling the extraction time, for example, using supercritical The extraction is carried out in combination with microwave extraction, wherein supercritical extraction is carried out for 5-10 min at a flow rate of 1000-2000 L/h, followed by microwave extraction for 10-15 min at a reaction volume of 1000-3000 L, in combination with supercritical extraction. When the extraction is carried out by means of microwave extraction, the extraction efficiency and the extraction yield are better under the above conditions. For example, by controlling extraction time, extraction pressure, extraction power, extraction temperature, and extraction flow rate, an optimized coordination scheme is adopted to better improve the efficiency of dissociating graphite powder into nano graphene, shorten the production cycle of nano graphene, and reduce Its production cost increases the quality of the produced graphene.

Or supercritical extraction combined with ultrasonic extraction, wherein supercritical extraction is carried out for 5-10 min at a flow rate of 1000-2000 L/h, followed by ultrasonic extraction for 10-15 min in a reaction volume of 1000-3000 L. When supercritical extraction is combined with ultrasonic extraction, the extraction efficiency and extraction yield are better under the above conditions.

Or supercritical extraction combined with ultra-high pressure extraction, wherein supercritical extraction is carried out for 5-10 min at a flow rate of 1000-2000 L/h, followed by ultra-high pressure extraction for 2-5 min at a flow rate of 1000-2000 L/h. When extraction is carried out by supercritical extraction combined with ultra-high pressure extraction, the extraction efficiency and extraction yield are better under the above conditions.

Or supercritical extraction combined with nano-abrasive extraction, wherein supercritical extraction is carried out for 5-10 min at a flow rate of 1000-2000 L/h, followed by a flow rate of 1000-5000 L/h or a reaction volume of 100-500 L. The nano-abrasive extraction was carried out for 10-15 min under conditions, and the extraction efficiency and extraction yield were better under the above conditions when supercritical extraction combined with nano-abrasive extraction.

Or by microwave extraction combined with ultrasonic extraction, wherein the microwave extraction is carried out for 10-15 min under the reaction volume of 1000-3000 L, and then continues in the reaction volume. Ultrasonic extraction was carried out for 10-15 min under the conditions of 1000-3000 L. When extraction was carried out by means of microwave extraction combined with ultrasonic extraction, the extraction efficiency and extraction yield were better under the above conditions.

Or adopting microwave extraction combined with ultra-high pressure extraction, wherein microwave extraction is carried out for 10-15 min under the reaction volume of 1000-3000 L, and then ultrahigh pressure extraction is continued for 2-5 min under the reaction volume of 1000-2000 L/h. When extracting by means of microwave extraction combined with ultra-high pressure extraction, the extraction efficiency and extraction yield are better under the above conditions.

Or by microwave extraction combined with nano-abrasive extraction, wherein the microwave extraction is carried out for 10-15 min in a reaction volume of 1000-3000 L, followed by a flow rate of 1000-5000 L/h or a reaction volume of 100-500 L. Nano-abrasive extraction for 10-15min, extraction by microwave extraction combined with nano-abrasive extraction, under the above conditions, extraction efficiency and extraction yield is better.

Or ultrasonic extraction combined with ultra-high pressure extraction, wherein the ultrasonic extraction is carried out for 10-15 min under the reaction volume of 1000-3000 L, and then the ultra-high pressure extraction is carried out for 2-5 min under the condition of regulating the flow rate of 1000-2000 L/h. When extraction is carried out by ultrasonic extraction combined with ultra-high pressure extraction, the extraction efficiency and extraction yield are better under the above conditions.

Or ultrasonic extraction combined with nano-abrasive extraction, wherein ultrasonic extraction is carried out for 10-15 min under a reaction volume of 1000-3000 L, followed by a flow rate of 1000-5000 L/h or a reaction volume of 100-500 L. Nano-abrasive extraction for 10-15min, extraction by ultrasonic extraction combined with nano-abrasive extraction, under the above conditions, extraction efficiency and extraction yield is better.

The above is merely exemplified by a method in which a combination of two extraction methods is used for extraction. It should be understood that supercritical extraction, ultrahigh pressure extraction, and microwave extraction may be used in combination, and before and after any combination of extractions. The order of the present invention is not specifically limited, and is within the scope of protection of the present invention, and is not enumerated here.

Preferably, in the extraction, a surface modifier and a solvent are added to the extracting agent, and the solvent is a polar solvent or a non-polar solvent, thereby causing the graphite powder in the system to undergo nanocrystallization dissociation by means of mechanical physicochemical energy. With a certain surface chemical modification, it not only saves the process, but also avoids the problem that the nanographene is prone to agglomeration, so that its application is no longer limited. As another implementation, during the extraction process, the inclusion A surface modifier and a solvent for dissolving the surface modifier are added to the mixed system of the extractant and the slurry, and the solvent is a polar solvent or a non-polar solvent. As another example, a surface modifier and a solvent for dissolving the surface modifier, which is a polar solvent or a non-polar solvent, are added to the extractant prior to extraction.

Specifically, those skilled in the art may add different modifiers according to actual conditions, such as a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, and a modifier commonly used in the field such as stearic acid. Specifically, different modifiers and polar solvents or non-polar solvents for dissolving different modifiers may be selected according to actual needs, and different reagents such as sulfonating reagents, carboxylating reagents, and the like may be selected. Any one or more of a branching reagent, an acetylating reagent, and a silylating reagent, thereby realizing a new function of imparting sulfonation, carboxylation, grafting, acetylation, silanization, etc. to the nano graphene, thereby improving The dispersibility and stability of the generated nanographene in different polar solutions improve its application value.

Filtration is the separation of the solids from the extracted extract. Filtration, preferably, filtration is carried out using an ultrafiltration membrane or a nanofiltration membrane having a pore size ranging from 1 to 100 nm. A filtrate having a ratio of graphene particles having a particle diameter of less than 100 nm and greater than or equal to 1 nm in the filtrate is equal to 100%. In other examples of the invention, the filter membrane may be a combination of two or three or four or five layers and more layers of ultrafiltration membranes and nanofiltration membranes. For example, the assembly is three layers, and is a three-layered laminated structure in which a nanofiltration membrane is disposed between two ultrafiltration membranes. Of course, the assembly may be a three-layer laminated structure in which an ultrafiltration membrane is provided between two nanofiltration membranes.

The filtered filtrate is dried; preferably, solid nanographene having a water content of 10-15% is prepared by vacuum drying to facilitate storage.

Preferably, the dried nanographene is packaged for storage and transportation.

The nanographene obtained by the above method has low cost and is widely used.

The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

Example 1

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1.. 2, adding water, and grinding to obtain a slurry.

Using liquid carbon dioxide as the extractant, supercritical extraction was carried out for 50 min at a pressure of 55 MPa, a power of 23 Kw, a temperature of 40 ° C and a flow rate of 1200 L/h, and then filtered using an ultrafiltration membrane having a pore size range of 60 nm to filter the residue. The second extraction and dissociation were carried out, and the filtrate was vacuum dried.

Example 2

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry.

Using liquid carbon dioxide as the extractant, at a frequency of 300MHz, a power of 7Kw, a temperature of 35 ° C, a reaction volume of 1000 L, microwave extraction for 46 min, the graphite powder is fully dissociated into graphene, and then a pore size of 10 nm is used. The filter membrane was filtered, and the filter residue was recovered for the second extraction and dissociation, and the filtrate was vacuum dried.

Example 3

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1.1.2, adding water, and grinding to obtain a slurry.

The liquid carbon dioxide is used as the extracting agent. When the frequency is 50KHz, the power is 25Kw, the temperature is 30°C, and the reaction volume is 1300L, ultrasonic extraction is performed for 50min to fully dissociate the graphite powder into nanographene, and then adopt a pore size range of 50nm. The nanofiltration membrane was filtered, and the filter residue was recovered for the second extraction and dissociation, and the filtrate was vacuum dried.

Example 4

A nanographene which is prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1.5, adding water, and grinding to obtain a slurry.

The liquid carbon dioxide is used as the extracting agent, and the surface modifier silane coupling agent and the solvent water are added at the same time, the pressure is 380 MPa, the power is 25 Kw, the temperature is 33 ° C, the flow rate is 2000 L/h, and the ultra-high pressure extraction is performed under overpressure for 5 min. The graphite powder is sufficiently dissociated into nanographene, and then filtered through an ultrafiltration membrane having a pore size of 1 nm, and the residue is recovered for a second extraction and dissociation, and the filtrate is vacuum dried.

Example 5

Using liquid carbon dioxide as the extractant, under the conditions of pressure of 50 MPa, power of 5 kW, temperature of 15 ° C, flow rate of 2000 L / h, over-pressure for 4 min for nano-abrasive extraction, and then filtration using a nanofiltration membrane with a pore size range of 100 nm. The residue was recovered for a second extraction and dissociated, and the filtrate was vacuum dried.

Example 6

Using water as the extractant, the supercritical extraction is first carried out. The supercritical extraction is carried out at a pressure of 60 MPa, a power of 13 Kw, a temperature of 40 ° C, a flow rate of 2000 L/h, extraction for 7 min, then a frequency of 50 KHz, a power of 20 Kw, When the reaction volume was 1000 L at a temperature of 30 ° C, ultrasonic extraction was carried out for 10 min, followed by filtration using an ultrafiltration membrane having a pore diameter of 90 nm, and the residue was recovered for the second extraction and dissociation, and the filtrate was vacuum dried.

Example 7

Taking liquid carbon dioxide as the extractant, microwave extraction is first carried out. The microwave extraction is performed at a frequency of 915 MHz, a power of 25 Kw, a temperature of 20 ° C, a reaction volume of 3000 L, extraction for 15 min, then a pressure of 80 MPa, a power of 25 KW, and a temperature. After 30 ° C and a reaction volume of 500 L, an overpressure of 13 min was carried out for nano-abrasive extraction, followed by filtration through a nanofiltration membrane having a pore size of 100 nm, and the residue was recovered for a second extraction dissociation, and the filtrate was vacuum dried.

Example 8

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry. Using liquid carbon dioxide as the extractant, the pressure was 30 MPa, the power was 9Kw, the temperature was 30 ° C, the flow rate was 1100 L / h, supercritical extraction was carried out for 50 min, and then the ultrafiltration membrane with a pore size range of 50 nm was used for filtration, and the filtrate was filtered. It was obtained by vacuum drying.

Example 9

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry. Using liquid carbon dioxide as the extractant, the supercritical extraction was carried out for 50 min at a pressure of 76 MPa, a power of 20 Kw, a temperature of 18 ° C, and a flow rate of 1800 L/h, and then filtered through a nanofiltration membrane having a pore size range of 90 nm. It was obtained by vacuum drying.

Example 10

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry. Using water as the extractant, supercritical extraction was carried out for 60 min at a pressure of 37 MPa, a power of 13 Kw, a temperature of 10 ° C and a flow rate of 1200 L/h, and then a nanofiltration membrane having a pore size range of 90 nm and an ultrafiltration membrane of 70 nm were used. The combined membrane provided by lamination was filtered, and the filtrate was vacuum dried.

Example 11

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry. Using water as the extractant, at a pressure of 30 MPa, a power of 13 Kw, a temperature of 12 ° C, a flow rate of 1100 L / h, supercritical extraction for 60 min, then a nanofiltration membrane with a pore size range of 90 nm and an ultrafiltration membrane of 80 nm The combined membrane provided by lamination was filtered, and the filtrate was vacuum dried.

Example 12

A nano graphene which is prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..3, adding water, and grinding to obtain a slurry. Using water as the extractant, under the pressure of 55MPa, the power is 19Kw, the temperature is 26 °C, the flow rate is 1700L / h, supercritical extraction is carried out for 80min, then filtered by a nanofiltration membrane with a pore size range of 100nm, and the filtrate is vacuumed. Dryed.

Example 13

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..4, adding water, and grinding to obtain a slurry. The liquid carbon dioxide is used as the extractant, and the pressure is 370 MPa, the power is 5Kw, the temperature is 10 °C, microwave extraction is carried out for 50 min, and then the ultrafiltration membrane with the pore size range of 80 nm is used for filtration, and the filter residue is recovered for the second extraction, and the filtrate is further It is dried under an inert gas atmosphere.

Example 14

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry. The liquid carbon dioxide was used as an extractant at a pressure of 900 MPa, a power of 20 Kw, a temperature of 7 ° C, microwave extraction for 30 min, followed by filtration through a nanofiltration membrane having a pore size range of 40 nm, and the filtrate was vacuum dried.

Example 15

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry. Using water as the extractant, the pressure was 426 MPa, the power was 8 Kw, the temperature was 7 ° C, microwave extraction was carried out for 80 min, and then the membrane was filtered using a nanofiltration membrane with a pore size range of 70 nm and a 70 nm ultrafiltration membrane stack. The filtrate was dried under vacuum.

Example 16

A nano graphene which is prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..6, adding water, and grinding to obtain a slurry. Water was used as an extractant at a pressure of 875 MPa, a power of 17 Kw, a temperature of 23 ° C, microwave extraction for 30 min, and then filtration using an ultrafiltration membrane having a pore size range of 70 nm, and the filtrate was vacuum dried.

Example 17

A nano graphene which is prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..3, adding water, and grinding to obtain a slurry. Water was used as an extractant at a pressure of 400 MPa, a power of 25 Kw, a temperature of 18 ° C, microwave extraction for 80 min, followed by filtration through a nanofiltration membrane having a pore size range of 100 nm, and the filtrate was vacuum dried.

Example 18

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry. Using water as the extractant, ultra-high pressure extraction was carried out for 50 min under the conditions of pressure of 250 MPa, power of 20 Kw, temperature of 11 ° C and flow rate of 1200 L/h, and then filtration was carried out by using ultrafiltration membrane with a pore size range of 70 nm to recover the residue. A second extraction is carried out, and the filtrate is further dried under an inert gas atmosphere.

Example 19

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry. Using water as the extractant, the pressure was 270 MPa, the power was 23 Kw, the temperature was 15 ° C, and the flow rate of 2000 L/h was subjected to ultra-high pressure extraction for 30 min, then filtered through a nanofiltration membrane having a pore size range of 90 nm, and the filtrate was vacuum dried. .

Example 20

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry. Using water as the extractant, the pressure was 380 MPa, the power was 13 Kw, the temperature was 28 ° C, and the flow rate was 1800 L/h for ultra-high pressure extraction for 60 min. Then, a nanofiltration membrane with a pore size range of 50 nm and a 50 nm ultrafiltration membrane laminate were used. The combined membrane is filtered and the filtrate is vacuum dried. Income.

Example 21

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1.6, adding water, and grinding to obtain a slurry. Using liquid carbon dioxide as extractant, ultra-high pressure extraction was carried out for 30 min at a pressure of 300 MPa, a power of 13 Kw, a temperature of 20 ° C, and a flow rate of 1600 L/h. Then, a nanofiltration membrane having a pore size of 70 nm was used for filtration, and the residue was recovered. The second extraction was dissociated, and the filtrate was dried under vacuum.

Example 22

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1.1.2, adding water, and grinding to obtain a slurry. Using water as extractant, under the conditions of pressure 50 MPa, power 16Kw, temperature 16 ° C, flow rate 1700 L / h, nano-abrasive extraction for 40 min, then filtration through a nanofiltration membrane with a pore size range of 80 nm, the filtrate It was obtained by vacuum drying.

Example 23

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry. Using water as the extractant, the nano-abrasive extraction was carried out for 50 min under the conditions of a pressure of 80 MPa, a power of 15 Kw, a temperature of 29 ° C and a flow rate of 3000 L/h, and then filtered with an ultrafiltration membrane having a pore size range of 70 nm to recover the filter residue. A second extraction is carried out, and the filtrate is further dried under an inert gas atmosphere.

Example 24

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry. Water was used as an extractant at a pressure of 77 MPa, a power of 20 Kw, a temperature of 19 ° C, and subjected to nano-abrasive extraction for 30 min, followed by filtration through a nanofiltration membrane having a pore size range of 90 nm, and the filtrate was vacuum dried.

Example 25

A nanographene prepared by the following method: adding graphite powder according to a ratio of dry to wet ratio of 1..1, adding water, and grinding to obtain a slurry. The water was used as an extractant at a pressure of 77 MPa, a power of 20 Kw, a temperature of 19 ° C, and subjected to nano-abrasive extraction for 50 min, followed by filtration through a nanofiltration membrane having a pore size range of 70 nm, and the filtrate was vacuum dried.

Repeating Examples 1-25, obtaining a sufficient amount of nanographene, the same quality of graphite, to obtain the same weight of nanographene compared to the existing conventional preparation process of graphene, required by embodiments of the present invention The time is only 1-3h, which can effectively save 10-40% of time and improve production efficiency.

The nanographene prepared in the embodiment 1-25 of the invention is used for preparing a plastic film, that is, the nano graphene powder is scientifically matched with the plastic powder, heated, melted and mixed, and finally blown into a shape. It has been measured that the transmittance and thermal efficiency of the plastic film to which the nano graphene is added are close to 100% as compared with the plastic film to which the nano graphene is not added.

The nanographene prepared in the embodiment 1-25 of the invention is used for preparing a PE solar panel, that is, the nano graphene powder is heated and melted and mixed together with the PE powder, and then pressed and formed, and measured, and the nano graphene is not added. Compared with the PE sunshine board, the PE solar panel to which the nano graphene is added has a light transmittance and a thermal efficiency close to 100%.

In summary, the present invention provides a nano graphene and a preparation method thereof, and the nano graphene has excellent properties, and the method can effectively improve the productivity of industrial production of nano graphene and reduce the production cost, and has excellent performance. The value of commercial promotion.

The embodiments described above are a part of the embodiments of the invention, and not all of the embodiments. The detailed description of the embodiments of the invention is not intended to All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Claims

A method for preparing nano graphene, characterized in that it comprises:

Mixing graphite powder with water and refining to obtain a slurry;

The slurry is extracted with water or liquid carbon dioxide as an extractant, and filtered to obtain a filtrate, which is dried.
The preparation method according to claim 1, wherein a surface modifier and a solvent for dissolving the surface modifier are added to the extractant before extraction, the solvent being a polar solvent or Non-polar solvent.
The preparation method according to claim 1, wherein a surface modifier and a solvent for dissolving the surface modifier are added to the mixed system containing the extractant and the slurry during the extraction process. a solvent which is a polar solvent or a non-polar solvent.
The preparation method according to claim 2 or 3, wherein the surface modifier comprises any one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, and stearic acid. .
The preparation method according to claim 2 or 3, wherein the surface modifier comprises a sulfonating agent, a carboxylating agent, a grafting reagent, an acetylating agent, and a silylation for modifying graphene. Any of the reagents.
The preparation method according to any one of claims 1 to 5, characterized in that the solid-liquid mixing system after extracting the slurry by the extracting agent is filtered by a filter.
The preparation method according to claim 6, wherein the filter membrane is any one or a combination of two of an ultrafiltration membrane and a nanofiltration membrane.
The method according to claim 7, wherein either or both of the ultrafiltration membrane and the nanofiltration membrane have a pore diameter ranging from 1 to 100 nm.
The preparation method according to any one of claims 1 to 8, wherein the extraction method comprises any one or more of supercritical extraction, microwave extraction, ultrasonic extraction, ultrahigh pressure extraction, and nanoabrasive extraction. combination.
The preparation method according to any one of claims 1 to 9, wherein the extraction method is supercritical extraction, and the conditions of supercritical extraction are:

25-80 MPa pressure, 5-25 KW power, 0 ° C < temperature ≤ 40 ° C, 1000-2000 L / h flow;

Or, a pressure of 30-76 MPa, a power of 9-20 KW, a flow rate of 0 ° C < temperature ≤ 30 ° C, 1100-1800 L / h;

Or, a pressure of 37-55 MPa, a power of 13-19 KW, a flow rate of 10 ° C < temperature ≤ 26 ° C, 1200-1700 L / h;

Alternatively, a pressure of 41-49 MPa, a power of 15-20 KW, a flow rate of 12 ° C < temperature ≤ 17 ° C, 1400-1500 L / h.
The preparation method according to any one of claims 1 to 9, wherein the extraction method is microwave extraction, and the conditions of microwave extraction are:

300-915MHz frequency, 5-25KW power, 0 °C < temperature ≤ 40 ° C;

Or, 370-900MHz frequency, 5-20KW power, 10 °C < temperature ≤ 30 ° C;

Or, a frequency of 426-875 MHz, a power of 8-17 KW, 7 ° C < temperature ≤ 23 ° C;

Alternatively, a frequency of 300-500 MHz, a power of 5-25 KW, 9 ° C < temperature ≤ 18 ° C.
The preparation method according to any one of claims 1 to 9, wherein the extraction method is ultrasonic extraction, and the conditions of ultrasonic extraction are:

20-50KHz frequency, 5-25KW power, 0 °C < temperature ≤ 40 ° C;

Or, a frequency of 20-40 KHz, a power of 5-20 KW, 9 ° C < temperature ≤ 36 ° C;

Or, a frequency of 25-42 KHz, a power of 9-10 KW, 15 ° C < temperature ≤ 30 ° C;

Alternatively, a frequency of 30-43 KHz, a power of 15-22 KW, and a temperature of 7 ° C < temperature ≤ 20 ° C.
The preparation method according to any one of claims 1 to 9, wherein the extraction method is ultrahigh pressure extraction, and the conditions of the ultrahigh pressure extraction are:

250-380MPa pressure, 5-25KW power, 0 °C < temperature ≤ 40 ° C, 1000-2000 L / h flow;

Or, a pressure of 250-350 MPa, a power of 5-20 KW, a flow rate of 11 ° C < temperature ≤ 40 ° C, 1200-1800 L / h;

Or, a pressure of 270-300 MPa, a power of 10-23 KW, a flow rate of 15 ° C < temperature ≤ 30 ° C, 1300-1600 L / h;

Alternatively, a pressure of 300-380 MPa, a power of 5-13 KW, a flow rate of 20 ° C < temperature ≤ 28 ° C, 1000-1500 L / h.
The preparation method according to any one of claims 1 to 9, wherein the extraction method is nano-abrasive extraction, and the conditions of nano-abrasive extraction are:

50-80 MPa pressure, 5-25 KW power, 0 ° C < temperature ≤ 40 ° C, 1000-5000 L / h flow;

Or, a pressure of 50-70 MPa, a power of 16-25 KW, a flow rate of 16 ° C < temperature ≤ 30 ° C, 1700-4000 L / h;

Or, a pressure of 70-80 MPa, a power of 5-15 KW, a flow rate of 10 ° C < temperature ≤ 29 ° C, 1000-3000 L / h;

Alternatively, a pressure of 50-77 MPa, a power of 8-20 KW, a flow rate of 9 ° C < temperature ≤ 19 ° C, 2000-3000 L / h.
The preparation method according to claim 1, wherein the graphite powder after refining has a particle diameter of 5 to 30 μm, or 9 to 27 μm, or 12 to 20 μm, or 16 to 19 μm.
The nanographene obtained by the production method according to any one of claims 1 to 15.