Method for increasing yield of graphene prepared by supercritical fluid through pretreatment of natural graphite

A supercritical fluid, natural graphite technology, applied in graphene, bulk chemical production, nano-carbon, etc., can solve problems such as unsatisfactory yield, and achieve the effect of improving yield and maintaining electrical and thermal properties

Active Publication Date: 2014-12-24
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is exactly in order to overcome the problem that supercritical fluid exfoliates natural graphite and prepares the problem of unsatisfactory yield in the graphene method, has proposed the low-temperature natural graphite slurry that acid is weakly treated in advance as the feedstock of autoclave, prepares graphene, The yield of graphene is greatly improved, and at the same time, the intrinsic properties of graphene are not compromised

Method used

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  • Method for increasing yield of graphene prepared by supercritical fluid through pretreatment of natural graphite

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Experimental program
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Effect test

Embodiment 1

[0036] Add the natural graphite powder and 95% concentrated sulfuric acid into the container according to the weight ratio of 10:1, and use ultrasonic stirring method, after stirring for 20 minutes, filter out the excess acid. Add ethanol by 3% of graphite powder weight, and stir evenly. Transfer the material to a cryogenic container and allow the material to cool to -10°C. Then the low-temperature material is quickly sprayed into a high-pressure reactor filled with supercritical ethanol, and the temperature of the high-pressure reactor is maintained at 245° C. and the pressure is 6.5 MPa. After the material stays in the autoclave for 60 minutes, it is quickly sprayed into the normal pressure production tank. The material was filtered, separated, washed, dried and the solid product collected. The solid product was added to a fresh dimethylformamide solution again, dispersed by ultrasonic waves for 120 minutes, left to stand for 12 hours, and then the precipitate was removed ...

Embodiment 2

[0038]Add natural graphite powder and 80% concentrated hydrochloric acid into the container according to the weight ratio of 1:2, adopt mechanical stirring method, and after stirring for 40 minutes, filter out excess acid. Add ethanol by 5% of graphite powder weight, and stir evenly. Transfer the material to a cryogenic container and allow the material to cool to -20°C. Then the low-temperature material is quickly sprayed into a high-pressure reactor filled with supercritical N-methylpyrrolidone. The temperature of the high-pressure reactor is maintained at 445° C. and the pressure is 4.8 MPa. After the material stays in the autoclave for 90 minutes, it is quickly sprayed into the normal pressure production tank. The material was filtered, separated, washed, dried and the solid product collected. The solid product was added to a fresh dimethylformamide solution again, dispersed by ultrasonic waves for 120 minutes, left to stand for 12 hours, and then the precipitate was remo...

Embodiment 3

[0040] Add the natural graphite powder and 90% concentrated nitric acid into the container according to the weight ratio of 1:1, adopt the mechanical stirring method, and after stirring for 50 minutes, centrifuge off the excess acid. Add ethylene glycol by 1% of graphite powder weight, and stir evenly. Transfer the material to a cryogenic container and allow the material to cool to -5°C. Then the low-temperature material is quickly sprayed into a high-pressure reactor filled with supercritical dimethylformamide. The temperature of the high-pressure reactor is maintained at 370° C. and the pressure is 6 MPa. After the material stays in the autoclave for 120 minutes, it is quickly sprayed into the normal pressure production tank. The material was filtered, separated, washed, dried and the solid product collected. The solid product was added to a fresh dimethylformamide solution again, dispersed by ultrasonic waves for 120 minutes, left to stand for 12 hours, and then the preci...

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Abstract

The invention relates to a method for increasing the yield of graphene prepared by a supercritical fluid through pretreatment of natural graphite. The method comprises the steps as follows: natural graphite powder and acid are added into a container and stirred uniformly; an additive is added, and the mixture is cooled to obtain low-temperature graphite slurry; the low-temperature graphite slurry is sprayed to a high-pressure reaction kettle containing supercritical fluid media for supercritical treatment; and then a material after the supercritical treatment is rapidly sprayed into a normal-pressure production material tank and is filtered, separated and dried to obtain the graphene product. Compared with the prior art, the low-temperature natural graphite slurry pretreated by the acid is taken as feedstock; compared with the normal-temperature natural graphite serving as feedstock, the yield of graphene is increased by about 2-5 times through the supercritical fluid stripping process; and not only is the yield of graphene increased, but also the electrical property and the thermal property of graphene are further maintained.

Description

technical field [0001] The invention belongs to the technical field of nanometer material preparation, and in particular relates to a method for improving the yield of graphene prepared by supercritical fluid through pretreatment of natural graphite. Background technique [0002] Due to the unique properties of graphene, it has broad application prospects in many fields. In order to realize the commercial application of graphene, the most critical issue is to obtain a large amount of high-quality graphene. At present, there are many methods how to prepare graphene, such as mechanical exfoliation method, chemical reduction method and so on. The graphene obtained by the mechanical exfoliation method has excellent electrical properties, but the yield is very low; the redox method can realize large-scale production of graphene, however, the electrical properties of the obtained graphene are not ideal. Supercritical fluid has excellent surface wetting ability, low surface tensi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B31/04C01B32/184
CPCY02P20/54
Inventor 胡国新高寒阳刘长青
Owner SHANGHAI JIAO TONG UNIV
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