CN113772665B

CN113772665B - Method for preparing graphene on large scale by using high-solid-content filter cake

Info

Publication number: CN113772665B
Application number: CN202111097305.5A
Authority: CN
Inventors: 路广; 刘同浩; 李磊; 任晓弟; 马乐; 韩卫
Original assignee: Shandong Jinlite New Material Co ltd
Current assignee: Shandong Jinlite New Material Co ltd
Priority date: 2021-07-06
Filing date: 2021-09-18
Publication date: 2022-07-22
Anticipated expiration: 2041-09-18
Also published as: CN113772665A; CN113307256A

Abstract

The invention relates to a method for preparing graphene on a large scale by using a high-solid-content filter cake, which belongs to the field of graphene preparation and is characterized in that graphene oxide is prepared by a Hummers method and the filter cake obtained by filter pressing is used as a raw material, the raw material is subjected to heat treatment at 500-1500 ℃ to obtain rough graphene powder, then the rough graphene powder is mixed with water and then is subjected to filter pressing to obtain a cake, the cake is washed and subjected to filter pressing to obtain a purified graphene filter cake, and finally the purified graphene filter cake is dried to obtain graphene powder; the method is simple and easy to implement, greatly improves the preparation efficiency of the graphene, and is beneficial to large-scale industrial production of the graphene.

Description

Method for preparing graphene on large scale by using high-solid-content filter cake

Technical Field

The invention relates to the field of graphene preparation, in particular to a method for preparing graphene on a large scale by using a high-solid-content filter cake.

Background

The graphene preparation technology is developed rapidly. The graphene has excellent performance and wide application prospect, and the rapid development of the graphene preparation technology is greatly promoted. The graphene material has the characteristics of quantum charge transmission, adjustable energy band gap, ultrahigh carrier mobility, excellent ferromagnetism, electromechanical regulation and control performance and the like. Based on these properties, graphene is widely used in the leading fields of organic electronics such as super capacitors, solar cells, lithium batteries, and optoelectronic devices. Since graphene is prepared by Geim and the like in 2004 for the first time by a micro-mechanical stripping method, researchers have developed numerous methods for preparing graphene. Among these, the mechanical exfoliation method, epitaxial growth method, chemical vapor deposition CVD method, graphite oxide reduction method, and the like are more mainstream methods.

The existing preparation method can not meet the requirements of graphene industrialization. The mechanical stripping method is simple to operate, high in sample preparation quality and is the main method for preparing single-layer high-quality graphene at present; but the controllability is poor, the prepared graphene has small size and great uncertainty, and meanwhile, the efficiency is low, the cost is high, and the method is not suitable for large-scale production. The epitaxial growth method has the defects that the number of layers of the graphene cannot be controlled, and impurities are easily doped in the preparation process. The CVD method is most commonly applied to the preparation of large-area graphene films at present, but the graphene films obtained by the CVD method are usually deposited on a metal substrate and cannot be directly applied to microelectronic devices. Particularly, the industrialization requires that the graphene preparation technology can stably produce large-area and high-purity graphene with low cost, and the problem of the preparation technology is not solved so far. The graphene prepared by the redox method has low cost, high yield and simple equipment requirement, and the product can stably exist in water or an organic solvent without subsequent substrate transfer, thereby providing a good industrial preparation method for the research and application of the graphene.

The redox method is to use graphite ore as a raw material and add an oxidant in a strong acid environment to obtain graphene oxide as a precursor. And then various oxygen-containing groups on the surface of the precursor are eliminated in a thermal reduction or chemical reduction mode, and finally the graphene is obtained. Wherein, the reducing reagent used in the chemical reduction method introduces new impurities, and the reagents have higher toxicity, which is not in accordance with the concept of green production, and the treatment cost of the waste liquid is higher. Therefore, the thermal reduction method is the best choice for the current industrial production of graphene.

At present, a method most suitable for the industrial production of graphene, namely a redox method, is required to purify to obtain pure graphene oxide after a graphene oxide precursor is prepared, and finally, the pure graphene oxide is thermally reduced to graphene. However, graphene oxide is highly hydrophilic in an aqueous solution, and is easily gelled when the pH value is increased. If a filter press is used for filter pressing, solid-liquid separation is easy to realize only in a strong acid environment, which is equivalent to introducing impurity acid in the washing process. If the membrane is used for washing, the working hours are long, and a large amount of waste water is generated in the washing process. Therefore, the purification of graphene oxide becomes a bottleneck restricting the mass production of graphene. There is currently no effective solution to this problem.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for preparing graphene on a large scale by using a high solid content filter cake, which is easy to realize industrialization in an enlarged scale and is simple and feasible, aiming at the defects of the prior art and the difficulty in the industrialization of the graphene at present, and the preparation efficiency of the graphene is greatly improved.

The technical scheme for solving the technical problems is as follows: a method for preparing graphene on a large scale by using filter cakes with high solid content is characterized in that,

preparing graphene oxide by a Hummers method, performing filter pressing to obtain a filter cake as a raw material, and performing heat treatment at 500-1500 ℃ to obtain crude graphene powder; under a high-temperature environment, oxygen-containing groups in the graphite oxide filter cake are broken, and the graphite oxide is reduced into graphene;

then adding water into the rough graphene powder, mixing, and performing filter pressing to obtain a cake;

washing and filter pressing to obtain a purified graphene filter cake; because the graphite oxide filter cake is not purified before thermal reduction, the filter cake contains acid and other impurities, and the impurities are removed by washing to obtain a purified graphene filter cake;

and finally, drying, and removing residual moisture in the graphene filter cake to obtain dry graphene powder.

The preparation of the graphene oxide by the Hummers method comprises the following steps: adding concentrated sulfuric acid into a reaction kettle, adding graphite powder while stirring, adding potassium permanganate in batches, controlling the reaction temperature to be 0-30 ℃, stirring for reaction, then heating to 30-50 ℃, continuing stirring, then slowly adding deionized water, controlling the temperature to be 50-90 ℃, continuously stirring, and then adding hydrogen peroxide to reduce the residual oxidant.

The preparation of the graphene oxide by using the Hummers method is suitable for industrial mass production, and the graphene oxide prepared by the method has good processability. Specifically, adding 10 g of graphite powder into 150-2000 mL of concentrated sulfuric acid under stirring, adding 5-60 g of potassium permanganate, controlling the reaction temperature to be 0-30 ℃, stirring for reaction for 1-5 hours, heating to 30-50 ℃, continuing stirring for 10-60 min, slowly adding 300-4000 mL of deionized water, controlling the temperature to be 50-90 ℃, continuing stirring for 5-30 min, and adding 10-120 mL of hydrogen peroxide to reduce residual oxidant. Filter pressing the mixture into filter cakes through a filter press.

Further, the heat treatment time is 10-60 min.

Further, the ratio of the crude graphene powder to water is 1: 10-1: 50, and then press-filtering to obtain a cake.

Further, the drying condition is drying for 3-10 hours at 50-80 ℃.

The invention has the beneficial effects that: the invention breaks through the traditional inertial thinking, adjusts the production process sequence, adopts the process route of directly thermally reducing the impurity-containing graphene oxide filter cake prepared by the Hummers method into the impurity-containing graphene filter cake, then purifying to obtain the graphene, and replaces the prior art of firstly preparing the graphene oxide, then purifying and finally thermally reducing the graphene oxide into the graphene.

Detailed Description

The invention is described in further detail below to facilitate the public's understanding of the manner in which the invention is practiced, and the examples are given by way of illustration only and are not intended to limit the scope of the invention.

Example 1

The preparation method of the graphene comprises the following steps:

1. adding 10 g of graphite powder into 150 mL of concentrated sulfuric acid under stirring, adding 5 g of potassium permanganate, controlling the reaction temperature at 0-15 ℃, stirring for 5 hours, then heating to 50 ℃, continuing to stir for 10 min, slowly adding 300 mL of deionized water, controlling the temperature at 60-80 ℃, continuing to stir for 5 min, and then adding 10 mL of hydrogen peroxide to reduce the residual oxidant. Filter pressing the mixture into filter cakes through a filter press.

2. The graphite oxide filter cake was transferred to a tube furnace. Treating at 500 deg.C for 45 min. And obtaining crude graphene powder.

3. Mixing and stirring the rough graphene powder and water according to the proportion of 1:50 for 30 min, and performing pressure filtration by a pressure filter to obtain a cake. And repeatedly washing and filter pressing for three times to obtain a purified graphene filter cake.

4. And (3) putting the purified graphene filter cake into an oven, and drying for 5 h at 50 ℃. And obtaining the graphene powder.

Example 2

The preparation method of the graphene comprises the following steps:

1. adding 10 g of graphite powder into 500 mL of concentrated sulfuric acid under stirring, adding 30 g of potassium permanganate, controlling the reaction temperature at 0-15 ℃, stirring for reaction for 2 hours, then heating to 30 ℃, continuing to stir for 30 minutes, slowly adding 1000 mL of deionized water, controlling the temperature at 50-60 ℃, continuing to stir for 20 minutes, and then adding 60 mL of hydrogen peroxide to reduce the residual oxidant. Filter pressing the mixture into filter cakes through a filter press.

2. The graphite oxide filter cake was transferred to a tube furnace. Treating at 900 deg.C for 10 min. And obtaining crude graphene powder.

3. Mixing and stirring the rough graphene powder and water according to the proportion of 1:20 for 30 min, and performing pressure filtration by a filter press to obtain a cake. And repeatedly washing and filter pressing for three times to obtain a purified graphene filter cake.

4. And (3) putting the purified graphene filter cake into an oven, and drying for 3 h at 80 ℃. And obtaining the graphene powder.

Example 3

The preparation method of graphene in this embodiment includes the following steps:

1. adding 10 g of graphite powder into 2000 mL of concentrated sulfuric acid under stirring, then adding 60 g of potassium permanganate, controlling the reaction temperature at 15-30 ℃, stirring for reaction for 1 h, then heating to 35 ℃, continuing to stir for 60 min, then slowly adding 4000 mL of deionized water, controlling the temperature at 80-90 ℃, continuing to stir for 30 min, and then adding 120 mL of hydrogen peroxide to reduce the residual oxidant. Filter pressing the mixture into filter cakes through a filter press.

2. The graphite oxide filter cake was transferred to a tube furnace. Treating at 1500 deg.C for 60 min. And obtaining crude graphene powder.

3. Mixing and stirring the crude graphene powder and water according to the proportion of 1:10 for 30 min, and performing pressure filtration through a pressure filter to obtain a cake. And repeatedly washing and filter pressing for three times to obtain a purified graphene filter cake.

4. And (3) putting the purified graphene filter cake into an oven, and drying for 10 hours at 70 ℃. And obtaining graphene powder.

The graphene prepared in the above embodiment has detected purity>95% of metal impurities<100 ppm, specific surface area 200-1000 m²(ii) a bulk density of 0.01 to 0.1 g/cm³Electrical conductivity of>400S/m. The process method for preparing the graphene has the characteristics of thorough reduction, high purity, large specific surface area, excellent electrical property and the like, is simple in process flow, and is a preparation method which is easy for large-scale industrial mass production.

Claims

1. A method for preparing graphene on a large scale by using high-solid-content filter cakes is characterized in that graphene oxide is prepared by a Hummers method and is subjected to filter pressing to obtain a graphite oxide filter cake as a raw material, the graphite oxide filter cake is subjected to heat treatment at 500-1500 ℃ to obtain crude graphene powder, then the crude graphene powder is mixed with water and is subjected to filter pressing to obtain a cake, the cake is washed and subjected to filter pressing to obtain a purified graphene filter cake, and finally the graphene powder is obtained by drying.

2. The method for preparing graphene on a large scale by using a high-solid-content filter cake according to claim 1, wherein the Hummers method is used for preparing graphene oxide by: adding concentrated sulfuric acid into a reaction kettle, adding graphite powder while stirring, adding potassium permanganate again, controlling the reaction temperature to be 0-30 ℃, stirring for reaction, then heating to 30-50 ℃, continuing stirring, then slowly adding deionized water, controlling the temperature to be 50-90 ℃, continuously stirring, and then adding hydrogen peroxide to reduce residual oxidant.

3. The method for preparing graphene on a large scale by using the high-solid-content filter cake according to claim 1, wherein the heat treatment time is 10-60 min.

4. The method for preparing graphene on a large scale by using the high-solid-content filter cake according to claim 1, wherein the ratio of the crude graphene powder to water is 1: 10-1: 50, and then press-filtering to obtain a cake.

5. The method for preparing graphene on a large scale by using the high-solid-content filter cake according to claim 1, wherein the drying condition is that the graphene is dried at 50-80 ℃ for 3-10 hours.