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CN-122010103-A - Method for preparing graphene by metal and molten salt composite system

CN122010103ACN 122010103 ACN122010103 ACN 122010103ACN-122010103-A

Abstract

The invention provides a method for preparing graphene by a metal and molten salt composite system, which comprises the following steps of (1) heating catalyst raw materials, reacting under protective gas to obtain a molten medium catalyst, wherein the molten medium catalyst is a composite catalyst formed by metal clusters and metal salt, (2) introducing first-class reaction gas for reaction, (3) introducing protective gas, cooling to obtain crude graphene, and (4) washing the crude graphene to obtain graphene. The invention adopts the metal cluster and molten salt composite catalyst, has high catalytic activity of metal and good dispersibility and stability of molten salt, effectively promotes the cracking of a carbon source and the nucleation growth of graphene, and the obtained graphene has higher graphitization degree and lower metal impurity content, and can realize high-efficiency separation by washing the product without complex post-treatment.

Inventors

  • ZHANG SHUCHEN
  • DONG JINGJING
  • ZHAO MANYU
  • QIAN JUN
  • YU QIJUN
  • YUE LIYING
  • YU JUN
  • PAN WENYAN
  • MENG HAO

Assignees

  • 东华工程科技股份有限公司
  • 中国科学技术大学

Dates

Publication Date
20260512
Application Date
20260302

Claims (10)

  1. 1. A method for preparing graphene by a metal and molten salt composite system, which comprises the following steps: (1) Heating the catalyst raw material, and reacting to obtain a molten medium catalyst, wherein the molten medium catalyst is a composite catalyst formed by metal clusters and metal salts; (2) Introducing a first type of reaction gas to react; (3) Then introducing protective gas, and cooling to obtain crude graphene; (4) And washing the crude graphene to obtain graphene.
  2. 2. The method of claim 1, wherein the molten medium catalyst is prepared according to the following method: and (3) mixing and grinding the metal oxide nano particles and the metal salt, heating to a first temperature, introducing protective gas for heat preservation, heating to a second temperature, and introducing a second type of reaction gas for heat preservation again to obtain the molten medium catalyst.
  3. 3. The method of claim 1, wherein the temperature of the reaction in step (1) is 750-1000 ℃.
  4. 4. The method according to claim 1, wherein the first type of reaction gas is a carbon source gas or a mixture of a carbon source gas and a shielding gas; The carbon source gas is selected from one or more of methane, ethane, propane, butane, ethylene, natural gas and liquefied petroleum gas; The shielding gas is selected from one or more of nitrogen, argon and hydrogen.
  5. 5. The method of claim 2, wherein the metal oxide nanoparticles are selected from one or more of iron oxide, nickel oxide, cobalt oxide, molybdenum oxide, and tungsten oxide; The metal oxide nano particles account for 0.1-20wt% of the metal salt.
  6. 6. The method of claim 2, wherein the metal salt is selected from one or more of potassium chloride, sodium chloride, magnesium chloride, calcium chloride, zinc chloride, copper chloride, lithium chloride, manganese chloride, rubidium chloride, cesium chloride, strontium chloride, barium chloride, ferrous chloride, cobalt chloride, and nickel chloride.
  7. 7. The method according to claim 2, wherein the second type of reaction gas is a mixture of argon and hydrogen in a volume ratio of (1:10) - (10:1).
  8. 8. The method of claim 2, wherein the first temperature is 200-600 ℃, and the temperature is kept for 5-10 hours; the second temperature is 750-1000 ℃, and the heat preservation time is 3-8 hours.
  9. 9. The method of claim 8, wherein the temperature is raised to the first temperature at 8-12 ℃ per minute; heating to a second temperature at 5-10 ℃ per minute.
  10. 10. The method according to claim 1, wherein the washing mode is water washing or water washing and acid washing; the water washing mode is one or more of centrifugation, suction filtration and pressure filtration; the acid solution used for pickling is one or more selected from hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid.

Description

Method for preparing graphene by metal and molten salt composite system Technical Field The invention belongs to the technical field of carbon material preparation, and particularly relates to a method for preparing graphene by a metal and molten salt composite system. Background Graphene has great application potential in the fields of energy, materials, electronics and the like due to a unique two-dimensional structure and excellent electrical, thermal and mechanical properties. Realizing high-efficiency, low-cost and large-scale preparation of graphene is a key for promoting practical application of graphene. Among the preparation methods, chemical Vapor Deposition (CVD) can prepare high-quality graphene films, but there are general problems of difficult substrate transfer, high cost, and the like. The graphene is prepared by cracking the carbon source, and the method has the advantages of co-production of hydrogen, simple process path and rich and clean carbon source, and becomes an attractive technical route. The liquid phase characteristic of the fused medium is favorable for dissolving, diffusing and self-assembling carbon atoms into graphene, and the product is easy to separate from the reaction medium due to the density difference, so that the fused medium has the potential of continuous production in theory. However, the reaction temperature of the molten metal system is usually extremely high, the energy consumption is high, the content of metal impurities in the generated carbon product is high, the catalytic activity of the molten salt system is low, the conversion efficiency of carbon source gas is poor, the graphitization degree of the carbon product is not high, and high-quality graphene with controllable layer number is difficult to obtain. Therefore, there is an urgent need in the art to develop a novel cracking process that can achieve efficient catalytic cracking of a carbon source at a relatively mild temperature and directly produce graphene of high quality, easy to separate and low in impurity content. Disclosure of Invention In view of the above, the present invention aims to provide a method for preparing graphene by using a metal and molten salt composite system, wherein the graphene prepared by the method has a higher graphitization degree and a lower metal impurity content. The invention provides a method for preparing graphene by a metal and molten salt composite system, which comprises the following steps: (1) Heating the catalyst raw material under the protection gas, and reacting to obtain a molten medium catalyst, wherein the molten medium catalyst is a composite catalyst formed by metal clusters and metal salts; (2) Introducing a first type of reaction gas to react; (3) Then introducing protective gas, and cooling to obtain crude graphene; (4) And washing the crude graphene to obtain graphene. Preferably, the molten medium catalyst is prepared according to the following method: and (3) mixing and grinding the metal oxide nano particles and the metal salt, heating to a first temperature, introducing protective gas for heat preservation, heating to a second temperature, introducing a second type of reaction gas and preserving heat to obtain the molten medium catalyst. Preferably, the reaction temperature in the step (1) is 750-1000 ℃. Preferably, the first type of reaction gas is a carbon source gas, or a mixed gas of a carbon source gas and a shielding gas; The carbon source gas is selected from one or more of methane, ethane, propane, butane, ethylene, natural gas and liquefied petroleum gas; The shielding gas is selected from one or more of nitrogen, argon and hydrogen. Preferably, the metal oxide nanoparticles are selected from one or more of iron oxide, nickel oxide, cobalt oxide, molybdenum oxide, and tungsten oxide; The metal oxide nano particles account for 0.1-20wt% of the metal salt. Preferably, the metal salt is selected from one or more of potassium chloride, sodium chloride, magnesium chloride, calcium chloride, zinc chloride, copper chloride, lithium chloride, manganese chloride, rubidium chloride, cesium chloride, strontium chloride, barium chloride, ferrous chloride, cobalt chloride and nickel chloride. Preferably, the second type of reaction gas is hydrogen. Preferably, the first temperature is 200-600 ℃, and the heat preservation is carried out for 5-10 hours; the second temperature is 750-1000 ℃, and the heat preservation time is 3-8 hours. Preferably, the temperature is raised to a first temperature at 8-12 ℃ per minute; heating to a second temperature at 5-10 ℃ per minute. Preferably, the washing mode is water washing or water washing and acid washing; the water washing mode is one or more of centrifugation, suction filtration and pressure filtration; the acid solution used for pickling is one or more selected from hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid. The invention provides a method for preparing graphene by a metal and mol