▎ 摘　　要

NOVELTY - Preparation of graphene involves dissolving coal asphalt in organic solvent to form an organic solution, weighing two or more metal salts of a predetermined weight, preparing corresponding saturated solutions with deionized water as a solvent, uniformly stirring in a beaker, slowly adding ethanol to the solution until the metal salt recrystallizes out from the solution, drying recrystallized metal salt, mixing, reducing melting temperature of the mixed metal salt, adding to the organic solution, uniformly stirring, transferring to an oven to remove excess organic solvent to obtain a mixture of coal asphalt and metal salt, placing the mixture in a tube furnace with flowing inert gas, heating, heat-preserving, cooling obtained product to room temperature with the furnace, filtering, washing obtained product with deionized water, collecting upper layer floating substance of the washing liquid, and drying. USE - Preparation of graphene. ADVANTAGE - The method is capable of preparing graphene by recycling low-temperature molten salt with simple technique, controllable low temperature, low cost, high operation efficiency, high production efficiency, and high production process safety, without using strong acid and strong alkali, not easy to generate pollution waste liquid, and environment-friendly. The melting temperature of the mixed metal salt can be changed by adjusting the proportion and type of the metal salt, it is convenient to reduce the preparation temperature, and it is good for reducing the energy consumption. The metal molten salt is recycled, repeatedly used, which is good in reducing the preparation cost. The used raw material is coal asphalt, the price is low, easy to obtain, and is convenient for industrial popularization and application. DETAILED DESCRIPTION - Preparation of graphene involves weighing a predetermined weight of coal asphalt, taking a predetermined volume of organic solvent, dissolving the coal asphalt in the organic solvent to form an organic solution, weighing two or more metal salts of a predetermined weight, preparing corresponding saturated solutions with deionized water as a solvent, uniformly stirring in a beaker, slowly adding ethanol to the solution until the metal salt recrystallizes out from the solution, drying recrystallized metal salt, mixing, reducing melting temperature of the mixed metal salt, adding to the organic solution, uniformly stirring, transferring to an oven to remove excess organic solvent to obtain a mixture of coal asphalt and metal salt, placing the mixture in a tube furnace with flowing inert gas, heating to a predetermined temperature at a predetermined heating rate, heat-preserving for predetermined period of time, cooling obtained product to room temperature with the furnace, filtering, washing obtained product with deionized water, collecting upper layer floating substance of the washing liquid, drying to obtain graphene, collecting and filtering the deionized water after cleaning the molten metal salt, drying, and recrystallizing the molten metal salt which can be recycled.