CN103935991A - Method for large-scale continuous preparation of high-quality graphene - Google Patents

Abstract

A large-scale continuous method for preparing high-quality graphene is to pump the entire feeding, puffing and receiving system to 0-1000Pa; heat the puffing furnace to 150-1000°C and keep it at a constant temperature; Under the action of the system pumping, the graphene powder is obtained through the heating zone of the furnace body, and the residence time in the heating zone is 30-1000s; the graphene powder enters the cyclone separator driven by the airflow formed by the vacuum system pumping, and the graphite The ene powder separates from the gas and falls into a collector. The invention has the advantages of simple equipment, convenient operation, low energy consumption and suitable for large-scale production.

Description

A large-scale continuous method for preparing high-quality graphene

technical field

The invention belongs to a method for preparing graphene, in particular to a method for large-scale and continuous preparation of high-quality graphene.

Background technique

Graphene is a two-dimensional crystal in which carbon atoms are arranged in a hexagonal manner. Since its discovery by scientists at the University of Manchester in 2004, graphene has become the focus of scientific and industrial attention. The thickness of graphene is only 0.335 nm, which is not only the thinnest known material, but also very strong and hard; as a single substance, it can transfer electrons faster than all known conductors and semiconductors at room temperature. At the same time, as a single-layer carbon atom structure, the theoretical specific surface area of graphene is as high as 2630m ² /g. Therefore, graphene has a wide range of applications in the fields of hydrogen storage, new lithium-ion batteries, supercapacitors, and fuel cells.

At present, the main preparation methods of graphene are physical method and chemical method. The physical method mainly includes micromechanical exfoliation method, epitaxial growth method, etc. Although the graphene prepared by physical method has fewer defects, it is limited by equipment and technology, and the cost is high. It is not easy to be prepared on a large scale; chemical methods usually include thermal reduction of graphite oxide method, reducing agent reduction of graphite oxide method, etc. However, functionalized graphene can be prepared on a large scale by graphite oxide thermal expansion method, and has a good application prospect in the field of energy storage. Therefore, the preparation of graphite oxide from graphite is considered as a strategic starting point for the large-scale preparation of graphene.

The Chinese invention patent with the publication number CN101935035B discloses a method for preparing graphene with a high specific surface area by ultra-low temperature thermal expansion, which realizes the exfoliation of graphene at a lower temperature. However, this method is a batch preparation method, and the reaction time is as long as 24 h, so continuous production cannot be realized, and the production efficiency is too low.

CN102139873A discloses a material method for preparing graphene by micro-irradiation in a vacuum or an inert gas environment. This method has strict requirements on equipment, cumbersome operation, discontinuous preparation process, and is not suitable for large-scale batch preparation.

Contents of the invention

The object of the present invention is to provide a method for large-scale continuous preparation of high-quality graphene, which has simple equipment, convenient operation, low energy consumption, and is suitable for large-scale production.

The technical solution adopted by the present invention to achieve the above object is: a method for large-scale continuous preparation of high-quality graphene, comprising the following steps:

(1) Turn on the vacuum system and pump the entire feeding, puffing and receiving system to 0-1000Pa;

(2) Heat the puffing furnace to 150-1000°C and keep the temperature constant;

(3) Turn on the feeding system, the graphite oxide powder passes through the heating zone of the furnace body under the action of its own gravity and vacuum system pumping, and the residence time in the heating zone is 30-1000s. After the graphite oxide is heated, it expands rapidly. while being reduced to obtain graphene powder;

(4) Driven by the airflow formed by the vacuum system, the graphene powder enters the cyclone separator, and the graphene powder is separated from the gas and falls into the collector.

The graphene produced by the invention is of extremely high quality, has a specific surface area of 600-2000 m ² /g, and has wide application prospects.

Compared with the prior art, the present invention adopts a large-capacity vacuum pump, which provides a higher degree of vacuum for the expansion and stripping of graphite oxide on the one hand, so that it can realize expansion, stripping and reduction at a lower temperature; On the one hand, relying on the airflow formed by the rapid pumping of the vacuum pump, the stripped graphene is brought to the cyclone separator for gas-solid separation and collection. The continuous operation of graphite oxide feeding, stripping and reduction, and graphene collection is realized, and the production efficiency is high, and the graphene produced is of high quality, with a specific surface area of 600-2000 m ² /g, and has broad application prospects. In addition, the method has simple equipment, convenient operation and low energy consumption, and is suitable for large-scale production.

Description of drawings

Fig. 1 is process flow chart;

Fig. 2 is the scanning electron micrograph of graphene product in embodiment 1.

Specific implementation examples

Example 1

(1) Turn on the vacuum system and pump the entire feeding, puffing and receiving system to 10 Pa;

(2) Heat the puffing furnace to 800°C and keep the temperature constant;

(3) Turn on the feeding system, the graphite oxide powder passes through the heating zone of the furnace body under the action of its own gravity and the pumping of the vacuum system, and the residence time in the heating zone is 300 s. Graphite oxide expands rapidly after being heated, and is reduced while peeling off to obtain graphene powder;

(4) Driven by the airflow formed by the vacuum system, the graphene powder enters the cyclone separator, and the graphene powder is separated from the gas and falls into the collector. The prepared graphene has a specific surface area of 1500 m ² /g;

Example 2

(1) Turn on the vacuum system and pump the entire feeding, puffing and receiving system to 300 Pa;

(2) Heat the puffing furnace to 150°C and keep the temperature constant;

(3) Turn on the feeding system, and the graphite oxide powder passes through the heating zone of the furnace body under the action of its own gravity and the pumping of the vacuum system, and the residence time in the heating zone is 30 s. Graphite oxide expands rapidly after being heated, and is reduced while peeling off to obtain graphene powder;

(4) Driven by the airflow formed by the vacuum system, the graphene powder enters the cyclone separator, and the graphene powder is separated from the gas and falls into the collector. The prepared graphene has a specific surface area of 600 m ² /g;

Example 3

(1) Turn on the vacuum system and pump the entire feeding, puffing and receiving system to 1000 Pa;

(2) Heat the puffing furnace to 800°C and keep the temperature constant;

(3) Turn on the feeding system, the graphite oxide powder passes through the heating zone of the furnace body under the action of its own gravity and the pumping of the vacuum system, and the residence time in the heating zone is 100 s. Graphite oxide expands rapidly after being heated, and is reduced while peeling off to obtain graphene powder;

(4) Driven by the airflow formed by the vacuum system, the graphene powder enters the cyclone separator, and the graphene powder is separated from the gas and falls into the collector. The prepared graphene has a specific surface area of 750 m ² /g;

Example 4

(1) Turn on the vacuum system and pump the entire feeding, puffing and receiving system to 500 Pa;

(2) Heat the puffing furnace to 1000°C and keep the temperature constant;

(3) Turn on the feeding system, and the graphite oxide powder passes through the heating zone of the furnace body under the action of its own gravity and the pumping of the vacuum system, and the residence time in the heating zone is 1000 s. Graphite oxide expands rapidly after being heated, and is reduced while peeling off to obtain graphene powder;

(4) Driven by the airflow formed by the vacuum system, the graphene powder enters the cyclone separator, and the graphene powder is separated from the gas and falls into the collector. The prepared graphene has a specific surface area of 1000 m ² /g;

Example 5

(1) Turn on the vacuum system and pump the entire feeding, puffing and receiving system to 1 Pa;

(2) Heat the puffing furnace to 1000°C and keep the temperature constant;

(3) Turn on the feeding system, the graphite oxide powder passes through the heating zone of the furnace body under the action of its own gravity and vacuum system pumping, and the residence time in the heating zone is 1500 s. Graphite oxide expands rapidly after being heated, and is reduced while peeling off to obtain graphene powder;

(4) Driven by the airflow formed by the vacuum system, the graphene powder enters the cyclone separator, and the graphene powder is separated from the gas and falls into the collector. The prepared graphene has a specific surface area of 2000 m ² /g.

Claims (2)

1. a method for continuously preparing high-quality graphene on a large scale, is characterized in that comprising the steps: (1) Turn on the vacuum system and pump the entire feeding, puffing and receiving system to 0-1000Pa; (2) Heat the puffing furnace to 150-1000°C and keep the temperature constant; (3) Turn on the feeding system, the graphite oxide powder passes through the heating zone of the furnace body under the action of its own gravity and vacuum system pumping, and the residence time in the heating zone is 30-1000s. After the graphite oxide is heated, it expands rapidly. while being reduced to obtain graphene powder; (4) Driven by the airflow formed by the vacuum system, the graphene powder enters the cyclone separator, and the graphene powder is separated from the gas and falls into the collector. 2. The product of a method for large-scale continuous preparation of high-quality graphene as claimed in claim 1, characterized in that the specific surface area of the prepared graphene is 600-2000 m ² /g.