WO2017048026A1 - Method for preparing graphene by using eutectic graphite - Google Patents

Method for preparing graphene by using eutectic graphite Download PDF

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WO2017048026A1
WO2017048026A1 PCT/KR2016/010285 KR2016010285W WO2017048026A1 WO 2017048026 A1 WO2017048026 A1 WO 2017048026A1 KR 2016010285 W KR2016010285 W KR 2016010285W WO 2017048026 A1 WO2017048026 A1 WO 2017048026A1
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graphite
graphene
graphene manufacturing
mixture
diamond
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French (fr)
Korean (ko)
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오철
이형윤
장강일
이현우
한동윤
김미선
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일진다이아몬드(주)
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
    • B01J3/06—Processes using ultra-high pressure, e.g. for the formation of diamonds; Apparatus therefor, e.g. moulds or dies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/10—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing sonic or ultrasonic vibrations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J6/00—Heat treatments such as Calcining; Fusing ; Pyrolysis

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  • the present invention relates to a graphene manufacturing method using a process graphite, and more particularly, the process graphite, which is a by-product generated during diamond manufacturing, is recycled as a raw material for graphene production, and graphene using process graphite can simplify the process. It relates to a manufacturing method.
  • Graphene is a two-dimensional material made of carbon atoms and has a honeycomb structure, and the types of graphene include single-layer graphene, two-layer graphene, and multi-layer graphene. Graphene or Graphite).
  • the thickness of the single layer graphene is very thin, about 0.34 nm, which is one carbon atom, but when the graphene sheet is overlapped to a thickness of mm, the strength is sufficient to support a two-ton car.
  • graphene is transparent and has a higher thermal conductivity than silver when absorbing only 2.3% of light, and moves electrons as if they have no mass, so that the flow of electricity is faster than that of conventional semiconductors. Be in the spotlight.
  • graphene is the most outstanding material among various materials with various characteristics such as strength, thermal conductivity, and electron mobility. It is applied to various fields such as display, secondary battery, solar cell, automobile, and lighting, and is strategic to drive the growth of related industries. It is recognized as a core material.
  • the method for preparing graphene includes a method of separating a layer of graphene from graphite crystals, a chemical vapor deposition method for synthesizing graphene using a transition metal that adsorbs carbon well at high temperature as a catalyst layer, and being adsorbed or contained in the crystal at high temperature.
  • a chemical vapor deposition method for synthesizing graphene using a transition metal that adsorbs carbon well at high temperature as a catalyst layer and being adsorbed or contained in the crystal at high temperature.
  • the chemical exfoliation method of oxidizing graphite and separating it from the solution phase and then reducing it is easy for mass production and chemical modification, which allows hybridization with other materials. Because of its merits, much research is ongoing.
  • graphite used as a raw material in the production of graphene is used for electrodes such as pencil cores, crucibles, electric furnaces, arcs, and the like as a lubricating material, and is also used when manufacturing synthetic diamond.
  • Synthetic diamond is used in the field of precision electronics and semiconductors as the demand for precision materials such as printed circuit board (PCB), light emitting diode (LED), and photovoltaic industry substrates is increasing.
  • industrial diamond is used as a basic abrasive for precision processing of various machinery, and as a cutting material and processing material of high strength materials, the value as a strategic material is becoming increasingly important.
  • particles having a particle size of less than 104 ⁇ m are referred to as industrial powder diamond, and such powdered synthetic diamond is manufactured by using a high temperature and high pressure process.
  • the high temperature and high pressure process of synthetic diamond is manufactured by sintering graphite and metals such as cobalt, nickel and iron at 1500 ° C. and 50,000 atmospheres. After sintering, after classifying diamond and precious metals, process graphite remains as a process by-product. At this time, the process graphite generated is disposed of, and thus, environmental pollution and cost loss are problematic.
  • the present invention provides a graphene manufacturing method using a process graphite that can shorten the process by performing a pre-treatment process of the graphene manufacturing process while performing a diamond manufacturing process.
  • the present invention provides a method for producing graphene using process graphite, which is environmentally friendly and has a raw material saving effect by recycling process graphite, which is a by-product of the discarded diamond manufacturing process, to high value-added industrial materials and recycling process graphite.
  • Graphene manufacturing method using a process graphite comprises a first step of producing a sintered body comprising diamond and unreacted graphite by sintering a mixed powder containing a metal and graphite; A second step of immersing the sintered body in a strong acid containing potassium permanganate (KMnO 4 ) and electrolyzing the mixture into a mixture containing diamond and graphite; Stripping the graphite in the mixture; A fourth step of recovering exfoliated graphene oxide; And a fifth step of reducing the recovered graphene oxide.
  • a strong acid containing potassium permanganate KnO 4
  • the strong acid introduced in the second step may include at least one of sulfuric acid (H 2 SO 4 ), phosphoric acid (H 3 PO 4 ), nitric acid (HNO 3 ) and hydrochloric acid (HCl).
  • sulfuric acid H 2 SO 4
  • phosphoric acid H 3 PO 4
  • nitric acid HNO 3
  • hydrochloric acid HCl
  • the additive added in the second step may further include sodium nitrate (NaNO 3 ) in potassium permanganate (KMnO 4 ).
  • the metal powder may include at least one of iron, nickel and cobalt.
  • the sintering may be performed at a temperature of 500 to 3000.
  • the sintering may be performed at a pressure of 40,000 atm to 60,000 atm.
  • the sintering may be performed for 40 to 80 minutes.
  • the third step may be performed by heat treatment or ultrasonic irradiation.
  • At least one reducing agent of hydrazine, sodium hydride, hydroquinone, sodium borohydride, ascorbic acid, and glucose is added. It can be performed by.
  • the method may further include a recovery step of recovering diamond from the mixture after the second step.
  • the recovery step may further recover the precious metal.
  • after the recovery step may further comprise the step of purifying the graphite in the mixture.
  • the method may further include treating the mixture with hydrogen peroxide (H 2 O 2 ) after the second step.
  • H 2 O 2 hydrogen peroxide
  • the present invention while performing a diamond manufacturing process, it is possible to easily obtain graphene oxide having good interlayer separation through one acid treatment of graphene manufacturing process and a simultaneous injection process of an oxidizing agent. By shortening the process, it is possible to reduce the process cost and improve productivity.
  • the present invention can reduce the cost of manufacturing graphene by recycling the process graphite which is a by-product discarded after the diamond manufacturing process as a raw material of the graphene, and additional costs such as waste treatment cost to discard the process graphite It also has the effect of reducing costs and minimizing environmental pollution.
  • the oxidizing agent in the form of an aqueous solution rather than a powder, the risk of the process may be lowered and productivity may be improved.
  • FIG. 1 is a flow chart showing a graphene manufacturing method using a process graphite according to an embodiment of the present invention.
  • FIG. 2 is a flow chart showing a graphene manufacturing method using a process graphite according to another embodiment of the present invention.
  • Graphene manufacturing method using a process graphite comprises a first step of producing a sintered body comprising diamond and unreacted graphite by sintering a mixed powder containing a metal and graphite; A second step of immersing the sintered body in a strong acid containing potassium permanganate (KMnO 4 ) and electrolyzing the mixture into a mixture containing diamond and graphite; Stripping the graphite in the mixture; A fourth step of recovering exfoliated graphene oxide; And a fifth step of reducing the recovered graphene oxide.
  • a strong acid containing potassium permanganate KnO 4
  • FIG. 1 is a flow chart showing a graphene manufacturing method using a process graphite according to an embodiment of the present invention.
  • Graphene manufacturing method using the process graphite according to the present embodiment is the first step (S100) to prepare a sintered body containing diamond and unreacted graphite by sintering the metal powder and graphite powder, potassium permanganate (KMnO 4 ) is A second step (S200) of immersing in a strong acid such as sulfuric acid (H 2 SO 4 ) added and electrolyzing to a mixture containing diamond and graphite, a third step (S300) of exfoliating graphite in the mixture, exfoliated Fourth step (S400) for recovering the graphene oxide, and a fifth step (S500) for reducing the recovered graphene oxide.
  • a strong acid such as sulfuric acid (H 2 SO 4 )
  • S300 third step
  • S400 exfoliated Fourth step
  • S500 for reducing the recovered graphene oxide.
  • the metal powder may include at least one of iron, nickel, and cobalt as a catalyst.
  • Graphite, iron, nickel, and cobalt powder are put in a cell of a certain size and sintered at high temperature and high pressure.
  • the sintering may be performed for 40 to 80 minutes at a temperature of 500 ⁇ 3000 °C, pressure 40,000 ⁇ 60,000 atm.
  • the sintered body is immersed in an aqueous solution of sulfuric acid (H 2 SO 4 ) to which potassium permanganate (KMnO 4 ) is added and electrolyzed.
  • the sintered body described above is formed in a state in which diamond, unreacted graphite, a catalyst metal, and the like are mixed. In this case, the sintered body is difficult to be separated into diamond, graphite, and catalytic metal by physical methods. Therefore, in the second step, the sintered body is separated into diamond, graphite, and catalytic metal, respectively, and converted into a physically easy mixture. .
  • the timing of adding potassium permanganate may be introduced at any time before and after the sintered body is added to the aqueous sulfuric acid solution.
  • the acid solution introduced in the second step may be any one of phosphoric acid (H 3 PO 4 ), nitric acid (HNO 3 ), and hydrochloric acid (HCl) in addition to sulfuric acid (H 2 SO 4 ).
  • the sintered compact is first immersed in an aqueous solution of sulfuric acid (H 2 SO 4 ), and then electrolyzed to convert the mixture into an easy physical separation mixture.
  • H 2 SO 4 sulfuric acid
  • Process to turn process graphite into graphite oxide should be carried out. This process is meaningful in that it increases the possibility of recycling resources by linking the diamond production and separation process with the graphene production process using graphite.
  • the graphene manufacturing method using the process graphite according to the present embodiment includes technical features for increasing efficiency in the manufacturing process in addition to the effect of producing graphene in an environment-friendly manner through the recycling of resources.
  • graphene is prepared using graphite as an element, a large amount of sulfuric acid and water must be used to induce a reaction for a long time for pretreatment of graphite. This leads to an increase in manufacturing costs and an increase in wastewater treatment costs, making it difficult to produce low-cost graphene.
  • the pretreatment process of graphite which must be used for graphene, takes a long time, and does not separately perform a process that requires the use of a large amount of sulfuric acid, potassium permanganate, and water.
  • the process can be shortened by performing simultaneously with the separation process of graphite (creation of a mixture).
  • the potassium permanganate (KMnO 4 ) aqueous solution introduced in the second step may further include sodium nitrate (NaNO 3 ).
  • the graphene is peeled off by heat-treating the process graphite as a by-product of the diamond process in the mixture or by applying ultrasonic waves.
  • the graphite oxide acid treated through the above process is easily dispersed in water and exists as a negatively charged thin film plate in a polar solvent.
  • the dispersed graphite oxide thin film plate is separated through ultrasonic grinding, it is formed of graphene oxide. It is also possible to use a rapid heating exfoliation method to separate the layer of expanded graphite oxide.
  • the potassium permanganate in step 2 (KMnO 4) is added sulfuric acid (H 2 SO 4) goes through the process of being immersed in the increase in the interlayer spacing of the process of graphite solution and are converted to a state in which the oxygen functional group of the inter-layer is inserted In the state in which the exfoliation step can be performed immediately without going through a separate pretreatment process of turning graphite into graphite oxide.
  • process graphite separated from the diamond manufacturing process was treated as waste, and even in the case of preparing graphene using this, process graphite is separated from the waste, purified and dried, and then added to sulfuric acid to form graphite oxide, permanganic acid.
  • the cost and efficiency of the manufacturing process such as the need to perform a pretreatment process by adding potassium (KMnO 4 ) to the reaction was not practical.
  • the process graphite is immediately delaminated by immersing the graphite powder in an aqueous sulfuric acid (H 2 SO 4 ) solution and potassium permanganate (KMnO 4 ) in the second step during the diamond manufacturing process. It is a state formed of graphite oxide which can be.
  • H 2 SO 4 aqueous sulfuric acid
  • KMnO 4 potassium permanganate
  • the graphene oxide thus formed may be used as it is, but in order to utilize the original electrical and physical properties of graphene, the graphene oxide must be reduced through physicochemical methods.
  • the graphene manufacturing method according to the present invention can be applied to a variety of known reduction methods, there is no particular limitation.
  • a hydrazine system As the reagent used in the chemical reduction method, a hydrazine system is mainly used.
  • hydrazine or sodium hydride When hydrazine or sodium hydride is used as a reducing agent, it is known to effectively remove epoxy groups or hydroxyl groups on the graphene surface but not carbonyl or carboxyl groups located at the edges. Such residual functional groups can be removed by sulfuric acid treatment or high temperature heat treatment. Thermal reduction occurs at temperatures above 200 degrees in an inert gas or reducing gas environment. Desorption of oxygen in graphene oxide occurs rapidly at high temperatures above 200 degrees and gradually occurs at temperatures below 200 degrees. Hydroquinone and sodium borohydride have been studied as alternative materials for hydrazine-based reducing agents.
  • reducing agents such as ascorbic acid (glucose), glucose (glucose) has been reported.
  • Other organic solvents such as basic aqueous solution, distilled water, dimethylformamide (DMF), methylacetamide, and n-methylpyrrolidinone (NMP) induce deoxidation reactions through normal heating or by using microwaves
  • DMF dimethylformamide
  • NMP n-methylpyrrolidinone
  • the reduction of graphene oxide may be performed in a basic solution, a supercritical aqueous solution, or even a solvent, and therefore, care should be taken when analyzing the chemical structure of graphene oxide.
  • it can be effectively reduced by the hydrogen plasma treatment, there are other electrochemical reduction, photocatalyst reduction, flash conversion (Flash conversion) method and the like.
  • FIG. 2 is a flowchart illustrating a graphene manufacturing method using eutectic graphite according to another embodiment.
  • the sintered body is immersed in sulfuric acid to which potassium permanganate is added, and then separated through electrolysis, so that the diamond, graphite and catalytic metals are easily recovered or separated from each other through a physical method. Convert to state
  • the process of recovering diamond or the like from the mixture converted through the second step S200 may be performed at any step after the second step S200. That is, it is possible to recover the diamond at any stage after the second step (S200), or to further collect and recover precious metals, or to separate and refine the process graphite from the mixture. That is, the graphite oxide is prepared in the form of a brown viscous slurry, and is formed of graphite oxide, exfoliated thin film oxide plate, unoxidized graphite chips and residues of oxidizing agent.
  • the graphite oxide can improve the quality and yield of graphene by removing impurities that sink through the purification process (S700) through centrifugation and selectively filtering the suspended graphite oxide to obtain purified graphite oxide.
  • the process of separating the process graphite from the mixture is applicable variously known filtration methods such as gravity filtration, pressure filtration, reduced pressure filtration, centrifugal filtration, osmotic filtration, there is no particular limitation on the filtration method.
  • H 2 O 2 treatment S800 may be performed for washing.
  • the graphite powder and the metal powder iron, nickel, cobalt powder is put in a cell of a constant size, and sintered for 60 minutes under a temperature of 1500 °C and 50,000 atm pressure.
  • the sintered compact is immersed in an aqueous solution of sulfuric acid (H 2 SO 4 ) to which potassium permanganate (KMnO 4 ) is added and electrolyzed.
  • An aqueous solution of sulfuric acid (H 2 SO 4 ) and potassium permanganate (KMnO 4 ) penetrate into the graphite to oxidize the graphite, increasing the interlayer spacing, and inserting an oxygen functional group between the layers.
  • the process of separating the mixture into the mixture during the diamond formation and pretreatment of the graphite for graphene production may be simultaneously performed, and the process of separately oxidizing the process graphite discharged as a byproduct may be omitted.
  • Process graphite separated from the mixture is separated in the state of graphite oxide, the process graphite may be treated with hydrogen peroxide (H 2 O 2 ) after the purification process.
  • H 2 O 2 hydrogen peroxide
  • the process graphite separated from the mixture is subjected to ultrasonic grinding to exfoliate.
  • Acid-treated graphite is easily dispersed in water and exists in the form of a thin film plate having a negative charge in a polar solvent.
  • the ultrasonic grinding method used in this embodiment forms such a graphite oxide thin film plate with graphene oxide. After the ultrasonic grinding, it is possible to form graphene oxide having a more uniform monolayer and area through a density gradient-centrifugation process.
  • exfoliated graphene oxide is recovered.
  • the recovered graphene oxide is reduced.
  • hydrazine or the like may be used as a reducing agent for reducing graphite oxide.

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Abstract

The present invention relates to a method for preparing graphene by using eutectic graphite. According to the present invention, the method for preparing graphene by using eutectic graphite comprises: a first step of preparing a sintered body, comprising diamond and unreacted graphite, by sintering a mixture powder comprising a metal and graphite; a second step of converting, by dipping the sintered body in a strong acid containing potassium permanganate (KMnO4) and carrying out electrolysis on the same into a mixture comprising diamond and graphite; a third step of stripping graphite within the mixture; a fourth step of recovering stripped graphene oxide; and a fifth step of reducing the recovered graphene oxide. According to the present invention, a process can be reduced by simultaneously carrying out a graphite pre-treatment step of in a process for preparing graphene and a process for preparing diamond, and thus there are effects of reducing reagents costs, which are required for pre-treatment, and processing costs.

Description

공정흑연을 이용한 그래핀 제조방법Graphene manufacturing method using eutectic graphite
본 발명은 공정흑연을 이용한 그래핀 제조방법에 관한 것으로서, 보다 상세하게는 다이아몬드 제조시 발생되는 부산물인 공정흑연을 그래핀 제조를 위한 원료로 재활용하고 공정을 간소화할 수 있는 공정흑연을 이용한 그래핀 제조방법에 관한 것이다.The present invention relates to a graphene manufacturing method using a process graphite, and more particularly, the process graphite, which is a by-product generated during diamond manufacturing, is recycled as a raw material for graphene production, and graphene using process graphite can simplify the process. It relates to a manufacturing method.
그래핀은 탄소 원자로 만들어진 2차원 물질로 벌집 모양 구조를 가지고 있으며, 그래핀의 종류로는 한층 그래핀(Single-Layer Graphene), 두층 그래핀(Two-Layer Graphene) 및 다층 그래핀(Multi-Layer Graphene 또는 Graphite) 등으로 나눌 수 있다. 단층 그래핀의 두께는 탄소원자 1개분인 약 0.34nm로 대단히 얇으나, 그래핀 시트를 겹쳐서 ㎜ 수준의 두께로 만들면 2톤짜리 자동차를 지지할 수 있는 강도가 발생할 정도로 매우 단단하다. 또한 그래핀은 투명하며 빛의 2.3%만을 흡수해도 상온에서 은보다 열전도성이 높으며, 전자가 마치 질량이 없는 것처럼 움직여 기존 반도체보다 전기의 흐름이 빨라질 수 있어 실리콘 기판을 대체할 수 있는 차세대 재료로 각광받고 있다.Graphene is a two-dimensional material made of carbon atoms and has a honeycomb structure, and the types of graphene include single-layer graphene, two-layer graphene, and multi-layer graphene. Graphene or Graphite). The thickness of the single layer graphene is very thin, about 0.34 nm, which is one carbon atom, but when the graphene sheet is overlapped to a thickness of ㎜, the strength is sufficient to support a two-ton car. In addition, graphene is transparent and has a higher thermal conductivity than silver when absorbing only 2.3% of light, and moves electrons as if they have no mass, so that the flow of electricity is faster than that of conventional semiconductors. Be in the spotlight.
이처럼, 그래핀은 강도, 열전도율, 전자이동도 등 여러 가지 특징이 현존하는 물질 중 가장 뛰어난 소재로 디스플레이, 이차전지, 태양전지, 자동차 및 조명 등 다양한 분야에 응용되어 관련 산업의 성장을 견인할 전략적 핵심소재로 인정받고 있다. As such, graphene is the most outstanding material among various materials with various characteristics such as strength, thermal conductivity, and electron mobility. It is applied to various fields such as display, secondary battery, solar cell, automobile, and lighting, and is strategic to drive the growth of related industries. It is recognized as a core material.
그래핀(graphene)을 제조하는 방법으로는 기계적 박리법, 화학적 박리법, 비산화 박리법, 화학증기증착법, 에피택시법 등 다양한 방법의 그래핀(graphene) 제조기술이 현재 사용되고 있다. 그래핀을 제조하는 방법에는 흑연결정으로부터 그래핀 한층을 분리하는 방법, 고온에서 탄소를 잘 흡착하는 전이금속을 촉매층으로 이용하여 그래핀을 합성하는 화학기상증착법 및 고온에서 결정에 흡착되어 있거나 포함되어 있던 탄소가 표면의 결을 따라 성장하는 에피성장법이 있으며, 특히 흑연을 산화시켜 용액상에서 분리한 후 환원시키는 화학적 박리법은 대량생산의 가능성과 화학적 개질이 용이하여 다른 소재와의 하이브리드가 가능하다는 장점 때문에 많은 연구가 진행중이다.As a method for producing graphene, graphene production techniques of various methods, such as mechanical peeling, chemical peeling, non-oxidative peeling, chemical vapor deposition, and epitaxy, are currently used. The method for preparing graphene includes a method of separating a layer of graphene from graphite crystals, a chemical vapor deposition method for synthesizing graphene using a transition metal that adsorbs carbon well at high temperature as a catalyst layer, and being adsorbed or contained in the crystal at high temperature. There is an epitaxial growth method in which carbon has grown along the surface texture. Especially, the chemical exfoliation method of oxidizing graphite and separating it from the solution phase and then reducing it is easy for mass production and chemical modification, which allows hybridization with other materials. Because of its merits, much research is ongoing.
하지만 현재 산화그래핀은 1kg당 최대 수억원에 이를 정도로 고가이기 때문에 대량생산 및 상용화에 어려움을 겪고 있어, 저렴한 비용으로도 그래핀을 제조할 수 있는 기술이 필요한 실정이다.However, since graphene oxide is expensive enough to reach hundreds of millions of dollars per kilogram, it is difficult to mass produce and commercialize, and thus, a technology for manufacturing graphene at a low cost is required.
한편, 그래핀 제조에서 원료로 사용되는 흑연은 연필심, 도가니, 전기로, 아크 등의 전극에 사용되고, 활마재로 사용하며 합성 다이아몬드를 제조할 때에도 사용된다. 합성 다이아몬드는 기존의 기간산업 분야용도 외에도 최근에는 인쇄회로기판(PCB), 발광다이오드(LED), 태양광산업용 기판 등 정밀 소재 가공 수요가 늘어나면서 정밀전자, 반도체 분야의 활용도 크게 늘고 있다. 또한, 공업용 다이아몬드는 각종 기계류의 정밀 가공의 기본 연마제로써 사용되며 그 외 고강도 소재의 절삭재료, 가공재료로 활용되어 전략소재로서의 가치가 점점 중요해지고 있다.On the other hand, graphite used as a raw material in the production of graphene is used for electrodes such as pencil cores, crucibles, electric furnaces, arcs, and the like as a lubricating material, and is also used when manufacturing synthetic diamond. Synthetic diamond is used in the field of precision electronics and semiconductors as the demand for precision materials such as printed circuit board (PCB), light emitting diode (LED), and photovoltaic industry substrates is increasing. In addition, industrial diamond is used as a basic abrasive for precision processing of various machinery, and as a cutting material and processing material of high strength materials, the value as a strategic material is becoming increasingly important.
일반적으로 입도가 104 μm보다 작은 것을 공업용 분말형 다이아몬드라고 하며, 이러한 분말형 합성다이아몬드는 고온고압공정을 이용하여 제조된다. 합성 다이아몬드의 고온고압공정은 흑연 및 코발트, 니켈, 철 등의 금속을 섭씨 1500℃ 및 5만기압 하에서 소결시켜 제조하며, 소결 후 다이아몬드 및 귀금속을 분류하고 나면 공정흑연이 공정 부산물로써 남게 된다. 이때 발생되는 공정흑연은 폐기처리되고 있으며, 이에따른 환경오염 및 비용손실이 문제가 되고 있는 실정이다.In general, particles having a particle size of less than 104 μm are referred to as industrial powder diamond, and such powdered synthetic diamond is manufactured by using a high temperature and high pressure process. The high temperature and high pressure process of synthetic diamond is manufactured by sintering graphite and metals such as cobalt, nickel and iron at 1500 ° C. and 50,000 atmospheres. After sintering, after classifying diamond and precious metals, process graphite remains as a process by-product. At this time, the process graphite generated is disposed of, and thus, environmental pollution and cost loss are problematic.
본 발명은 다이아몬드 제조 공정을 수행하면서, 그래핀 제조 공정의 전처리 과정을 동시에 수행하여 공정을 단축할 수 있는 공정흑연을 이용한 그래핀 제조방법을 제공한다.The present invention provides a graphene manufacturing method using a process graphite that can shorten the process by performing a pre-treatment process of the graphene manufacturing process while performing a diamond manufacturing process.
또한, 본 발명은 폐기되는 다이아몬드 제조 공정의 부산물인 공정흑연을 고부가가치의 산업소재로 재활용하고, 공정흑연을 재활용함으로써 친환경적이며 원료절감 효과가 있는 공정흑연을 이용한 그래핀 제조방법을 제공한다.In addition, the present invention provides a method for producing graphene using process graphite, which is environmentally friendly and has a raw material saving effect by recycling process graphite, which is a by-product of the discarded diamond manufacturing process, to high value-added industrial materials and recycling process graphite.
본 발명에 따른 공정흑연을 이용한 그래핀 제조방법은 금속 및 흑연을 포함하는 혼합 분말을 소결하여 다이아몬드 및 미반응 흑연을 포함하는 소결체를 제조하는 제1단계; 상기 소결체를 과망간산칼륨(KMnO4)을 포함한 강산 에 침지하고 전기분해하여 다이아몬드 및 흑연을 포함하는 혼합물로 변환하는 제2단계; 상기 혼합물 내의 흑연을 박리시키는 제3단계; 박리된 산화 그래핀을 회수하는 제4단계 ; 및 회수된 산화 그래핀을 환원시키는 제5단계;를 포함한다.Graphene manufacturing method using a process graphite according to the present invention comprises a first step of producing a sintered body comprising diamond and unreacted graphite by sintering a mixed powder containing a metal and graphite; A second step of immersing the sintered body in a strong acid containing potassium permanganate (KMnO 4 ) and electrolyzing the mixture into a mixture containing diamond and graphite; Stripping the graphite in the mixture; A fourth step of recovering exfoliated graphene oxide; And a fifth step of reducing the recovered graphene oxide.
또한 상기 제2단계에서 투입되는 강산은 황산(H2SO4), 인산(H3PO4), 질산(HNO3) 및 염산(HCl) 중 적어도 어느 하나를 포함할 수 있다.In addition, the strong acid introduced in the second step may include at least one of sulfuric acid (H 2 SO 4 ), phosphoric acid (H 3 PO 4 ), nitric acid (HNO 3 ) and hydrochloric acid (HCl).
또한 상기 제2단계에서 투입되는 첨가제로는 과망간산칼륨(KMnO4)에 질산나트륨(NaNO3)을 더 포함할 수 있다.In addition, the additive added in the second step may further include sodium nitrate (NaNO 3 ) in potassium permanganate (KMnO 4 ).
또한 상기 금속분말은 철, 니켈 및 코발트 중 적어도 어느 하나를 포함할 수 있다.In addition, the metal powder may include at least one of iron, nickel and cobalt.
또한 상기 제1단계에서 상기 소결은 500 내지 3000의 온도에서 수행될 수 있다.In addition, in the first step, the sintering may be performed at a temperature of 500 to 3000.
또한 상기 제1단계에서 상기 소결은 40,000atm 내지 60,000atm의 압력에서 수행될 수 있다.In the first step, the sintering may be performed at a pressure of 40,000 atm to 60,000 atm.
또한 상기 제1단계에서 상기 소결은 40 내지 80분 동안 수행될 수 있다.In addition, in the first step, the sintering may be performed for 40 to 80 minutes.
또한 상기 제3단계는 열처리 또는 초음파의 조사를 통하여 수행될 수 있다.In addition, the third step may be performed by heat treatment or ultrasonic irradiation.
또한 상기 제5단계는 하이드리진(hydrazine), 나트륨 하이드라이드, 하이드로퀴논(hydroquinone), 나트륨 보로하이드라이드(sodium borohydride), 아스코빅산(ascorbic acid) 및 글루코스(glucose) 중 적어도 어느 하나의 환원제의 투입에 의하여 수행될 수 있다.In a fifth step, at least one reducing agent of hydrazine, sodium hydride, hydroquinone, sodium borohydride, ascorbic acid, and glucose is added. It can be performed by.
또한 상기 제2단계 이후 상기 혼합물로부터 다이아몬드를 회수하는 회수단계를 더 포함할 수 있다.The method may further include a recovery step of recovering diamond from the mixture after the second step.
또한 상기 회수단계에서는 귀금속을 더 회수할 수 있다.In addition, the recovery step may further recover the precious metal.
또한 상기 회수 단계 이후 상기 혼합물 내의 흑연을 정제시키는 단계를 더 포함할 수 있다.In addition, after the recovery step may further comprise the step of purifying the graphite in the mixture.
또한 상기 제2단계 이후 상기 혼합물을 과산화수소(H2O2)처리하는 단계를 더 포함할 수 있다.The method may further include treating the mixture with hydrogen peroxide (H 2 O 2 ) after the second step.
본 발명에 따르면 다이아몬드 제조 공정을 수행하면서, 그래핀 제조공정의 1회의 산처리와 산화제의 동시 투입 프로세스를 통하여 층간 분리가 잘 되어 있는 산화 그래핀을 용이하게 얻을 수 있으며, 이와 같이 전처리 과정을 동시에 수행하여 공정을 단축함으로써 공정비용을 절감하고 생산성을 향상시키는 효과가 있다.According to the present invention, while performing a diamond manufacturing process, it is possible to easily obtain graphene oxide having good interlayer separation through one acid treatment of graphene manufacturing process and a simultaneous injection process of an oxidizing agent. By shortening the process, it is possible to reduce the process cost and improve productivity.
또한, 본 발명에 따르면 다이아몬드 제조 공정 후 폐기되는 부산물인 공정흑연을 재활용하여 그래핀의 원료로 사용함으로써 그래핀 제조 시 비용을 절감할 수 있으며, 공정흑연을 폐기하기 위한 폐기물 처리 비용 등의 추가비용 또한 절감하고 환경오염 문제를 최소화할 수 있는 효과가 있다.In addition, according to the present invention can reduce the cost of manufacturing graphene by recycling the process graphite which is a by-product discarded after the diamond manufacturing process as a raw material of the graphene, and additional costs such as waste treatment cost to discard the process graphite It also has the effect of reducing costs and minimizing environmental pollution.
또한 본 발명에 따르면 선택에 따라 산화제를 분말이 아닌 수용액 상태로 투입함으로써 공정의 위험성을 낮추고 생산성을 향상시키는 효과를 얻을 수 있다.In addition, according to the present invention, by selecting the oxidizing agent in the form of an aqueous solution rather than a powder, the risk of the process may be lowered and productivity may be improved.
도 1은 본 발명의 일 실시예에 따른 공정흑연을 이용한 그래핀 제조방법을 나타내는 순서도이다.1 is a flow chart showing a graphene manufacturing method using a process graphite according to an embodiment of the present invention.
도 2는 본 발명의 다른 실시예에 따른 공정흑연을 이용한 그래핀 제조방법을 나타내는 순서도이다.2 is a flow chart showing a graphene manufacturing method using a process graphite according to another embodiment of the present invention.
본 발명에 따른 공정흑연을 이용한 그래핀 제조방법은 금속 및 흑연을 포함하는 혼합 분말을 소결하여 다이아몬드 및 미반응 흑연을 포함하는 소결체를 제조하는 제1단계; 상기 소결체를 과망간산칼륨(KMnO4)을 포함한 강산 에 침지하고 전기분해하여 다이아몬드 및 흑연을 포함하는 혼합물로 변환하는 제2단계; 상기 혼합물 내의 흑연을 박리시키는 제3단계; 박리된 산화 그래핀을 회수하는 제4단계 ; 및 회수된 산화 그래핀을 환원시키는 제5단계;를 포함한다.Graphene manufacturing method using a process graphite according to the present invention comprises a first step of producing a sintered body comprising diamond and unreacted graphite by sintering a mixed powder containing a metal and graphite; A second step of immersing the sintered body in a strong acid containing potassium permanganate (KMnO 4 ) and electrolyzing the mixture into a mixture containing diamond and graphite; Stripping the graphite in the mixture; A fourth step of recovering exfoliated graphene oxide; And a fifth step of reducing the recovered graphene oxide.
이하 첨부된 도면을 참조하여 본 발명의 실시예를 설명한다. 특별한 정의나 언급이 없는 경우에 본 설명에 사용하는 방향을 표시하는 용어는 도면에 표시된 상태를 기준으로 한다. 또한 각 실시예를 통하여 동일한 도면부호는 동일한 부재를 가리킨다. 한편, 도면상에서 표시되는 각 구성은 설명의 편의를 위하여 그 두께나 치수가 과장될 수 있으며, 실제로 해당 치수나 구성간의 비율로 구성되어야 함을 의미하지는 않는다.Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Unless otherwise defined or mentioned, terms indicating directions used in the present description are based on the states shown in the drawings. In addition, the same reference numerals throughout the embodiments indicate the same member. On the other hand, each of the components shown in the drawings may be exaggerated in thickness or dimensions for the convenience of description, and does not mean that actually should be configured by the ratio between the dimensions or configurations.
먼저 도 1을 참조하여 본 발명의 일 실시예에 따른 공정흑연을 이용한 그래핀 제조방법을 설명한다. 도 1은 본 발명의 일 실시예에 따른 공정흑연을 이용한 그래핀 제조방법을 나타내는 순서도이다.First, a graphene manufacturing method using eutectic graphite according to an embodiment of the present invention will be described with reference to FIG. 1. 1 is a flow chart showing a graphene manufacturing method using a process graphite according to an embodiment of the present invention.
본 실시예에 따른 공정흑연을 이용한 그래핀 제조방법은 금속분말 및 흑연분말을 소결하여 다이아몬드 및 미반응 흑연을 포함하는 소결체를 제조하는 제1단계(S100), 소결체를 과망간산칼륨(KMnO4)이 첨가된 황산(H2SO4) 등의 강산 에 침지하고 전기분해하여 다이아몬드 및 흑연을 포함하는 혼합물로 변환하는 제2단계(S200), 혼합물 내의 흑연을 박리시키는 제 3단계(S300), 박리된 산화 그래핀을 회수하는 4단계(S400), 회수된 산화 그래핀을 환원시키는 제 5단계(S500)를 포함한다.Graphene manufacturing method using the process graphite according to the present embodiment is the first step (S100) to prepare a sintered body containing diamond and unreacted graphite by sintering the metal powder and graphite powder, potassium permanganate (KMnO 4 ) is A second step (S200) of immersing in a strong acid such as sulfuric acid (H 2 SO 4 ) added and electrolyzing to a mixture containing diamond and graphite, a third step (S300) of exfoliating graphite in the mixture, exfoliated Fourth step (S400) for recovering the graphene oxide, and a fifth step (S500) for reducing the recovered graphene oxide.
제1단계(S100)에서는 금속분말 및 흑연분말을 펠렛 형태로 제조한 후 고온고압 조건에서 소결하여 소결체를 형성한다. 이때 금속분말은 철, 니켈, 코발트 중 적어도 어느 하나를 촉매로서 포함할 수 있다. 흑연과 철, 니켈, 코발트 분말을 일정 크기의 셀에 넣고 고온고압으로 소결한다. 이 경우 소결은 500 ~ 3000℃의 온도, 40,000 ~ 60,000atm의 압력에서 40~80분 동안 수행될 수 있다.In the first step (S100) to prepare a metal powder and graphite powder in the form of pellets and then sintered under high temperature and high pressure conditions to form a sintered body. In this case, the metal powder may include at least one of iron, nickel, and cobalt as a catalyst. Graphite, iron, nickel, and cobalt powder are put in a cell of a certain size and sintered at high temperature and high pressure. In this case, the sintering may be performed for 40 to 80 minutes at a temperature of 500 ~ 3000 ℃, pressure 40,000 ~ 60,000 atm.
제2단계(S200)에서는 소결체를 과망간산칼륨(KMnO4)이 첨가된 황산(H2SO4) 수용액 에 침지하고 전기분해한다. 상술한 소결체는 다이아몬드, 미반응 흑연 및 촉매 금속등이 혼재된 상태로 형성된다. 이 경우 해당 소결체는 물리적인 방법으로 다이아몬드, 흑연 및 촉매 금속 등으로 분리가 어렵다, 따라서 제2단계에서는 소결체를 각각 다이아몬드, 흑연 및 촉매 금속으로 분리하여 물리적으로 분리가 용이한 혼합물의 상태로 변환시킨다. 과망간산칼륨의 투입시점은 소결체를 황산 수용액에 투입한 전 후의 어떤 시점에 투입할 수 있다.In the second step (S200), the sintered body is immersed in an aqueous solution of sulfuric acid (H 2 SO 4 ) to which potassium permanganate (KMnO 4 ) is added and electrolyzed. The sintered body described above is formed in a state in which diamond, unreacted graphite, a catalyst metal, and the like are mixed. In this case, the sintered body is difficult to be separated into diamond, graphite, and catalytic metal by physical methods. Therefore, in the second step, the sintered body is separated into diamond, graphite, and catalytic metal, respectively, and converted into a physically easy mixture. . The timing of adding potassium permanganate may be introduced at any time before and after the sintered body is added to the aqueous sulfuric acid solution.
제2단계에서 투입되는 산(acid) 용액은 황산(H2SO4) 이외에도 인산(H3PO4), 질산(HNO3) 및 염산(HCl) 중 어느 하나를 적용할 수 있다. The acid solution introduced in the second step may be any one of phosphoric acid (H 3 PO 4 ), nitric acid (HNO 3 ), and hydrochloric acid (HCl) in addition to sulfuric acid (H 2 SO 4 ).
이와 같이 다이아몬드 제조 과정에서 또는 제조 후의 공정흑연을 이용하여 그래핀을 제조하고자 하는 경우에는 먼저 소결체를 황산(H2SO4) 수용액에 침지한 후 전기분해하여 물리적 분리가 용이한 혼합물로 변환하고, 공정흑연을 산화흑연으로 만드는 공정을 수행하여야 한다. 이러한 공정은 다이아몬드 제조 및 분리 공정과 흑연을 이용한 그래핀 제조 공정을 연계시킴으로써 자원의 재활용 가능성을 높인다는 면에서 의미가 있다. As described above, when graphene is to be produced using graphite in the manufacturing process or after the manufacturing process, the sintered compact is first immersed in an aqueous solution of sulfuric acid (H 2 SO 4 ), and then electrolyzed to convert the mixture into an easy physical separation mixture. Process to turn process graphite into graphite oxide should be carried out. This process is meaningful in that it increases the possibility of recycling resources by linking the diamond production and separation process with the graphene production process using graphite.
본 실시예에 따른 공정흑연을 이용한 그래핀 제조방법은 이와 같이 자원의 재활용을 통하여 친환경적으로 그래핀을 제조하는 효과 이외에도 제조 공정상의 효율을 증가시키기 위한 기술적인 특징을 포함한다. 흑연을 원소재로 사용하여 그래핀을 제조하는 경우, 흑연의 전처리를 위하여 다량의 황산과 물을 사용하여 장시간 동안 반응을 유도해야 한다. 이는 제조 비용의 상승과 폐수 처리 비용의 증가를 가져와 저가의 그래핀을 만드는데 어려움을 발생시킨다. The graphene manufacturing method using the process graphite according to the present embodiment includes technical features for increasing efficiency in the manufacturing process in addition to the effect of producing graphene in an environment-friendly manner through the recycling of resources. When graphene is prepared using graphite as an element, a large amount of sulfuric acid and water must be used to induce a reaction for a long time for pretreatment of graphite. This leads to an increase in manufacturing costs and an increase in wastewater treatment costs, making it difficult to produce low-cost graphene.
그러나 본 실시예에 따른 제2단계를 수행함으로써 그래핀 제조에 사용되야만 하는 흑연의 전처리과정, 즉 장시간이 소요되며 다량의 황산과 과망간산칼륨, 물을 사용해야 하는 공정을 별도로 수행하지 않고 다이아몬드와 공정흑연의 분리 공정(혼합물의 생성)과 동시에 수행함으로써 공정을 단축시킬 수 있다.However, by performing the second step according to the present embodiment, the pretreatment process of graphite, which must be used for graphene, takes a long time, and does not separately perform a process that requires the use of a large amount of sulfuric acid, potassium permanganate, and water. The process can be shortened by performing simultaneously with the separation process of graphite (creation of a mixture).
이와 같이 소결체를 과망간산칼륨(KMnO4)이 첨가된 황산(H2SO4) 수용액 에 침지하고 전기분해하는 과정을 거치면 다이아몬드, 미반응 흑연 및 촉매 금속 등이 물리적으로 분리 용이한 상태로 존재하게 된다. 이 때 최초 흑연 투입량의 10%만 다이아몬드로 존재하며, 미반응된 나머지 공정흑연 90%과 금속분말이 혼합물 내에 존재한다. As such, when the sintered body is immersed in an aqueous solution of sulfuric acid (H 2 SO 4 ) to which potassium permanganate (KMnO 4 ) is added and electrolyzed, diamond, unreacted graphite, and a catalytic metal are present in a physically easy state. . At this time, only 10% of the initial graphite input is present as diamond, and the remaining 90% unreacted process graphite and metal powder are present in the mixture.
한편, 제2단계에서 투입되는 과망간산칼륨(KMnO4) 수용액에는 질산나트륨(NaNO3)을 더 포함할 수 있다.On the other hand, the potassium permanganate (KMnO 4 ) aqueous solution introduced in the second step may further include sodium nitrate (NaNO 3 ).
제3단계(S300)에서는 혼합물 내의 다이아몬드 공정 부산물로서의 공정흑연을 열처리하거나 또는 초음파를 조사하여 그래핀을 박리시킨다. 상기 공정을 통하여 산처리된 산화흑연은 물에서 분산이 용이하며 극성용매에서 음전하를 띤 박막 플레이트로 존재하게 되는데, 이렇게 분산된 산화흑연 박막 플레이트를 초음파 분쇄를 통해 박리하면 산화그래핀으로 형성된다. 또한, 팽창된 산화흑연의 층을 분리하기 위하여 급속 가열하는 박리법을 사용하는 것도 가능하다.In the third step (S300), the graphene is peeled off by heat-treating the process graphite as a by-product of the diamond process in the mixture or by applying ultrasonic waves. The graphite oxide acid treated through the above process is easily dispersed in water and exists as a negatively charged thin film plate in a polar solvent. When the dispersed graphite oxide thin film plate is separated through ultrasonic grinding, it is formed of graphene oxide. It is also possible to use a rapid heating exfoliation method to separate the layer of expanded graphite oxide.
제2단계에서 과망간산칼륨(KMnO4)이 첨가된 황산(H2SO4) 수용액에 침지되는 과정을 거치면서 공정흑연의 층간 간격이 증가하고, 층간에 산소 관능기가 삽입되어 있는 상태로 변환되기 때문에, 흑연을 산화흑연으로 만드는 별도의 전처리 과정을 거치지 않고 바로 박리단계를 수행할 수 있는 상태가 된다. The potassium permanganate in step 2 (KMnO 4) is added sulfuric acid (H 2 SO 4) goes through the process of being immersed in the increase in the interlayer spacing of the process of graphite solution and are converted to a state in which the oxygen functional group of the inter-layer is inserted In the state in which the exfoliation step can be performed immediately without going through a separate pretreatment process of turning graphite into graphite oxide.
종래에는 다이아몬드 제조공정에서 분리되어 나온 공정흑연은 폐기물로서 취급되었으며, 이를 이용하여 그래핀을 제조하고자 하는 경우에도 폐기물로부터 공정흑연을 분리, 정제 건조 한 후 황산에 투입하여 산화흑연을 형성하고, 과망간산칼륨(KMnO4)을 투입하여 반응시키는 전처리 과정을 수행하여야 하는 등 비용 및 제조 공정 상의 효율이 문제가 되어 실용적이지 못하였다.Conventionally, the process graphite separated from the diamond manufacturing process was treated as waste, and even in the case of preparing graphene using this, process graphite is separated from the waste, purified and dried, and then added to sulfuric acid to form graphite oxide, permanganic acid. The cost and efficiency of the manufacturing process, such as the need to perform a pretreatment process by adding potassium (KMnO 4 ) to the reaction was not practical.
하지만 본 실시예에 따른 공정흑연을 이용한 그래핀 제조방법에서는 다이아몬드 제조공정 시 제2단계에서 흑연분말을 황산(H2SO4) 수용액 및 과망간산칼륨(KMnO4) 에 침지시킴으로써 공정흑연이 바로 박리될 수 있는 산화흑연으로 형성되어 있는 상태이다. 이처럼, 그래핀 제조를 위한 흑연의 전처리 과정을 다이아몬드 제조공정 중의 분리과정과 동시에 수행하기 때문에 그래핀 제조 공정을 단축시킬 수 있으며, 그로 인한 비용과 시간을 절감할 수 있는 효과가 있다.However, in the graphene manufacturing method using the process graphite according to the present embodiment, the process graphite is immediately delaminated by immersing the graphite powder in an aqueous sulfuric acid (H 2 SO 4 ) solution and potassium permanganate (KMnO 4 ) in the second step during the diamond manufacturing process. It is a state formed of graphite oxide which can be. As such, since the pretreatment of graphite for graphene production is performed at the same time as the separation process in the diamond manufacturing process, the graphene manufacturing process can be shortened, thereby reducing the cost and time.
이렇게 형성된 산화그래핀 자체를 용도에 따라 그대로 사용할 수도 있지만, 그래핀 본래의 전기적, 물리적 특성을 활용하기 위해서는 산화그래핀을 물리화학적 방법을 통해 환원시켜야 한다. The graphene oxide thus formed may be used as it is, but in order to utilize the original electrical and physical properties of graphene, the graphene oxide must be reduced through physicochemical methods.
일반적으로 산화그래핀의 환원을 위해서 하이드라진계 환원제 및/또는 수소를 이용한 고온 열처리 과정 등을 거치게 된다.In general, a high temperature heat treatment process using a hydrazine-based reducing agent and / or hydrogen to reduce the graphene oxide.
즉, 제 5단계(S500)에서는 산화 그래핀을 환원시켜 사용 목적에 맞도록 전기적 특성 등을 향상시킨다. 다만, 본 발명에 따른 그래핀 제조방법은 공지된 환원 방법들을 다양하게 적용이 가능하며, 특별한 제한은 없다.That is, in the fifth step (S500) to reduce the graphene oxide to improve the electrical characteristics and the like to meet the purpose of use. However, the graphene manufacturing method according to the present invention can be applied to a variety of known reduction methods, there is no particular limitation.
화학적 환원법에 사용되는 시약은 하이드라진계가 주로 사용된다. 하이드라진이나 나트륨 하이드라이드를 환원제로 사용하는 경우 그래핀 표면의 에폭시기나 히드록시기는 효과적으로 제거하지만 가장자리에 위치한 카보닐기나 카르복실기는 제거하지 못하는 것으로 알려져 있다. 이러한 잔류 관능기는 황산처리나 고온 열처리를 통해 제거가 가능하다. 열적 환원은 불활성 가스나 환원 가스 환경에서 200도 이상의 온도에서 이루어진다. 산화 그래핀에서 산소의 탈착은 200도 이상의 높은 온도에서는 빠르게 일어나고 200도 이하의 온도에서는 점진적으로 일어난다. 하이드라진계 환원제의 대체 재료로는 하이드로퀴논(hydroquinone), 나트륨 보로하이드라이드(sodium borohydride)가 연구되었다. 친환경 환원제로는 아스코빅산(ascorbic acid), 글루코스(glucose) 등의 환원제가 보고되고 있다. 그 밖에 염기성 수용액, 증류수나 디메틸포름아미드(DMF), 메틸아세트아미드, n-메틸피롤리디논(NMP) 등의 유기용매에서 일반 가열을 통해 탈산화 반응을 유도하거나 마이크로파(mircowave)를 이용해 5~15분 정도의 짧은 시간에 환원을 시키는 방법이 연구되고 있다. 이처럼 산화 그래핀의 환원은 염기용액이나 초임계 수용액, 심지어 용매 내에서도 이루어질 수 있어 산화 그래핀의 화학적 구조분석 시 유의하여야 한다. 또한 수소플라즈마 처리에 의해 효과적으로 환원시킬 수 있으며, 그 밖에 전기화학적 환원법, 광촉매 환원법, 플래쉬 컨버전(Flash conversion)법 등이 있다.As the reagent used in the chemical reduction method, a hydrazine system is mainly used. When hydrazine or sodium hydride is used as a reducing agent, it is known to effectively remove epoxy groups or hydroxyl groups on the graphene surface but not carbonyl or carboxyl groups located at the edges. Such residual functional groups can be removed by sulfuric acid treatment or high temperature heat treatment. Thermal reduction occurs at temperatures above 200 degrees in an inert gas or reducing gas environment. Desorption of oxygen in graphene oxide occurs rapidly at high temperatures above 200 degrees and gradually occurs at temperatures below 200 degrees. Hydroquinone and sodium borohydride have been studied as alternative materials for hydrazine-based reducing agents. As an eco-friendly reducing agent, reducing agents such as ascorbic acid (glucose), glucose (glucose) has been reported. Other organic solvents such as basic aqueous solution, distilled water, dimethylformamide (DMF), methylacetamide, and n-methylpyrrolidinone (NMP) induce deoxidation reactions through normal heating or by using microwaves A method of reducing in a short time of about 15 minutes has been studied. As such, the reduction of graphene oxide may be performed in a basic solution, a supercritical aqueous solution, or even a solvent, and therefore, care should be taken when analyzing the chemical structure of graphene oxide. In addition, it can be effectively reduced by the hydrogen plasma treatment, there are other electrochemical reduction, photocatalyst reduction, flash conversion (Flash conversion) method and the like.
도 2를 참조하여 다른 실시예에 따른 공정흑연을 이용한 그래핀 제조방법을 설명한다. 도 2는 다른 실시예에 따른 공정흑연을 이용한 그래핀 제조방법을 나타내는 순서도이다.With reference to Figure 2 will be described a graphene manufacturing method using a process graphite according to another embodiment. 2 is a flowchart illustrating a graphene manufacturing method using eutectic graphite according to another embodiment.
앞서 설명한 바와 같이 제2단계(S200)에서는 소결체를 과망간산칼륨이 첨가된 황산에 침지한 후 전기분해를 통하여 분리함으로써 물리적인 방법을 통하여 다이아몬드, 흑연 및 촉매금속 들을 서로 회수하거나 분리하기가 용이한 혼합물 상태로 변환시킨다.As described above, in the second step (S200), the sintered body is immersed in sulfuric acid to which potassium permanganate is added, and then separated through electrolysis, so that the diamond, graphite and catalytic metals are easily recovered or separated from each other through a physical method. Convert to state
이와 같이 제2단계(S200)를 통하여 변환된 혼합물로부터 다이아몬드 등을 회수하는 공정(S600)은 제2단계(S200) 이후 어느 단계에서나 수행이 가능하다. 즉, 제2단계(S200) 이후 어느 단계에서 다이아몬드를 회수하거나, 귀금속을 추가적으로 더 분리 회수하는 것도 가능하며, 혼합물로부터 공정흑연을 분리하여 정제하는 것도 가능하다. 즉, 산화흑연은 갈색의 점성 슬러리 형태로 제조되며 산화흑연, 박리된 박막산화 플레이트, 산화되지 않은 흑연 조각 및 산화제의 잔유물들로 형성되어 있다. 따라서 산화흑연은 원심분리를 통한 정제과정(S700)을 통하여 가라앉는 불순물들을 제거하고 부유물인 산화흑연을 선택적으로 걸러 정제된 산화흑연을 수득함으로써 그래핀의 품질 및 수율을 향상시킬 수 있다. 혼합물로부터 공정흑연을 분리하는 과정은 중력 여과, 가압 여과, 감압 여과, 원심 여과, 삼투 여과 등 공지된 여과 방법들을 다양하게 적용가능하며, 여과 방법에 대한 특별한 제한은 없다.As such, the process of recovering diamond or the like from the mixture converted through the second step S200 may be performed at any step after the second step S200. That is, it is possible to recover the diamond at any stage after the second step (S200), or to further collect and recover precious metals, or to separate and refine the process graphite from the mixture. That is, the graphite oxide is prepared in the form of a brown viscous slurry, and is formed of graphite oxide, exfoliated thin film oxide plate, unoxidized graphite chips and residues of oxidizing agent. Therefore, the graphite oxide can improve the quality and yield of graphene by removing impurities that sink through the purification process (S700) through centrifugation and selectively filtering the suspended graphite oxide to obtain purified graphite oxide. The process of separating the process graphite from the mixture is applicable variously known filtration methods such as gravity filtration, pressure filtration, reduced pressure filtration, centrifugal filtration, osmotic filtration, there is no particular limitation on the filtration method.
이후, 일반적인 공정으로서 세척을 위하여 과산화수소(H2O2)처리(S800)를 할 수 있다.Thereafter, as a general process, hydrogen peroxide (H 2 O 2 ) treatment (S800) may be performed for washing.
이하에서는 본 발명에 따른 공정흑연을 이용한 그래핀 제조방법의 구체적인 바람직한 실시예 및 해당 실시예에 따른 각 단위 공정들을 상세히 설명한다.Hereinafter, a specific preferred embodiment of the graphene manufacturing method using the process graphite according to the present invention and each unit process according to the embodiment will be described in detail.
본 실시예에 따른 공정흑연을 이용한 그래핀 제조방법에 따라 흑연분말과 금속분말인 철, 니켈, 코발트 분말을 일정한 크기의 셀에 넣고, 1500℃의 온도와 50,000atm 기압 하에서 60분동안 소결한다. 소결체를 과망간산칼륨(KMnO4)이 첨가된 황산(H2SO4) 수용액에 침지하고 전기분해한다. 황산(H2SO4) 수용액과 과망간산칼륨(KMnO4)은 흑연 내로 침투하여 흑연을 산화시켜 층간 간격을 증가시키고, 그 층 사이로 산소관능기 삽입이 이루어지게 한다. 이처럼 다이아몬드 형성 중 혼합물로의 분리 과정과 그래핀 제조를 위한 흑연의 전처리 과정을 동시에 수행하여, 부산물로서 배출되는 공정흑연을 별도로 산화시키는 공정을 생략할 수 있다.According to the graphene manufacturing method using the process graphite according to this embodiment, the graphite powder and the metal powder iron, nickel, cobalt powder is put in a cell of a constant size, and sintered for 60 minutes under a temperature of 1500 ℃ and 50,000 atm pressure. The sintered compact is immersed in an aqueous solution of sulfuric acid (H 2 SO 4 ) to which potassium permanganate (KMnO 4 ) is added and electrolyzed. An aqueous solution of sulfuric acid (H 2 SO 4 ) and potassium permanganate (KMnO 4 ) penetrate into the graphite to oxidize the graphite, increasing the interlayer spacing, and inserting an oxygen functional group between the layers. As such, the process of separating the mixture into the mixture during the diamond formation and pretreatment of the graphite for graphene production may be simultaneously performed, and the process of separately oxidizing the process graphite discharged as a byproduct may be omitted.
다음으로, 전기분해 후 혼합물로부터 다이아몬드를 분리해내고 미반응된 공정흑연을 중력여과하여 분리해낸다. 혼합물로부터 분리된 공정흑연은 산화흑연 상태로 분리되며, 정제과정을 거친 후 공정흑연을 과산화수소(H2O2)처리 할 수 있다.Next, after electrolysis, diamond is separated from the mixture, and unreacted eutectic graphite is separated by gravity filtration. Process graphite separated from the mixture is separated in the state of graphite oxide, the process graphite may be treated with hydrogen peroxide (H 2 O 2 ) after the purification process.
다음으로 혼합물로부터 분리된 공정흑연을 초음파 분쇄하여 박리시킨다. 산처리된 흑연은 물에서 분산이 용이하며 극성용매에서 음전하를 띤 박막 플레이트 형태로 존재하게 되는데, 본 실시예에서 사용한 초음파 분쇄법은 이러한 산화흑연 박막플레이트를 산화그래핀으로 형성시킨다. 초음파 분쇄 후에는 밀도구배형-원심분리 과정을 통하여 보다 균일한 단일층 및 면적을 갖는 산화그래핀을 형성할 수 있다.Next, the process graphite separated from the mixture is subjected to ultrasonic grinding to exfoliate. Acid-treated graphite is easily dispersed in water and exists in the form of a thin film plate having a negative charge in a polar solvent. The ultrasonic grinding method used in this embodiment forms such a graphite oxide thin film plate with graphene oxide. After the ultrasonic grinding, it is possible to form graphene oxide having a more uniform monolayer and area through a density gradient-centrifugation process.
이후, 박리된 산화 그래핀을 회수한다. 다음으로 회수된 산화 그래핀을 환원시킨다. 앞서 설명한 바와 같이 산화흑연을 환원시키는 환원제로서 하이드리진(hydrazine) 등을 사용할 수 있다.Thereafter, exfoliated graphene oxide is recovered. Next, the recovered graphene oxide is reduced. As described above, hydrazine or the like may be used as a reducing agent for reducing graphite oxide.
이상 본 발명의 바람직한 실시예에 대하여 설명하였으나, 본 발명의 기술적 사상이 상술한 바람직한 실시예에 한정되는 것은 아니며, 특허청구범위에 구체화된 본 발명의 기술적 사상을 벗어나지 않는 범주에서 다양하게 구현될 수 있다.Although the preferred embodiment of the present invention has been described above, the technical idea of the present invention is not limited to the above-described preferred embodiment, and may be variously implemented in a range without departing from the technical idea of the present invention specified in the claims. have.

Claims (13)

  1. 금속 및 흑연을 포함하는 혼합 분말을 소결하여 다이아몬드 및 미반응 흑연을 포함하는 소결체를 제조하는 제1단계;A first step of sintering a mixed powder containing metal and graphite to produce a sintered body including diamond and unreacted graphite;
    상기 소결체를 과망간산칼륨(KMnO4)이 첨가된 강산에 침지하고 전기분해하여 다이아몬드 및 흑연을 포함하는 혼합물로 변환하는 제2단계;A second step of immersing the sintered body in a strong acid to which potassium permanganate (KMnO 4 ) is added and electrolyzing to a mixture containing diamond and graphite;
    상기 혼합물 내의 흑연을 박리시키는 제3단계;Stripping the graphite in the mixture;
    상기 박리된 산화 그래핀을 회수하는 제4단계; 및A fourth step of recovering the exfoliated graphene oxide; And
    회수된 산화 그래핀을 환원시키는 제5단계The fifth step of reducing the recovered graphene oxide
    를 포함하는 공정흑연을 이용한 그래핀 제조방법.Graphene manufacturing method using a process graphite comprising a.
  2. 제1항에 있어서,The method of claim 1,
    상기 제2단계에서 투입되는 강산은 황산(H2SO4), 인산(H3PO4), 질산(HNO3) 및 염산(HCl) 중 적어도 어느 하나를 포함하는 공정흑연을 이용한 그래핀 제조방법.The strong acid introduced in the second step is a graphene manufacturing method using process graphite including at least one of sulfuric acid (H 2 SO 4 ), phosphoric acid (H 3 PO 4 ), nitric acid (HNO 3 ), and hydrochloric acid (HCl). .
  3. 제1항에 있어서,The method of claim 1,
    상기 제2단계에서 투입되는 첨가제로는 과망간산칼륨(KMnO4)에 질산나트륨(NaNO3)을 더 포함하는 공정흑연을 이용한 그래핀 제조방법.As an additive to be added in the second step, a graphene manufacturing method using process graphite further comprising sodium nitrate (NaNO 3 ) in potassium permanganate (KMnO 4 ).
  4. 제1항에 있어서,The method of claim 1,
    상기 금속분말은 철, 니켈 및 코발트 중 적어도 어느 하나를 포함하는 공정흑연을 이용한 그래핀 제조방법.The metal powder is a graphene manufacturing method using a process graphite containing at least one of iron, nickel and cobalt.
  5. 제1항에 있어서,The method of claim 1,
    상기 제1단계에서 상기 소결은 500 내지 3000의 온도에서 수행되는 공정흑연을 이용한 그래핀 제조방법.In the first step, the sintering is a graphene manufacturing method using a process graphite is carried out at a temperature of 500 to 3000.
  6. 제1항에 있어서,The method of claim 1,
    상기 제1단계에서 상기 소결은 40,000atm 내지 60,000atm의 압력에서 수행되는 공정흑연을 이용한 그래핀 제조방법.In the first step, the sintering is a graphene manufacturing method using a process graphite is carried out at a pressure of 40,000 atm to 60,000 atm.
  7. 제1항에 있어서,The method of claim 1,
    상기 제1단계에서 상기 소결은 40 내지 80분 동안 수행되는 공정흑연을 이용한 그래핀 제조방법.In the first step, the sintering is a graphene manufacturing method using a process graphite is performed for 40 to 80 minutes.
  8. 제1항에 있어서,The method of claim 1,
    상기 제3단계는 열처리 또는 초음파의 조사를 통하여 수행되는 공정흑연을이용한 그래핀 제조방법.The third step is a graphene manufacturing method using the process graphite is carried out by heat treatment or ultrasonic irradiation.
  9. 제1항에 있어서,The method of claim 1,
    상기 제5단계는 하이드리진(hydrazine), 나트륨 하이드라이드, 하이드로퀴논(hydroquinone), 나트륨 보로하이드라이드(sodium borohydride), 아스코빅산(ascorbic acid) 및 글루코스(glucose) 중 적어도 어느 하나의 환원제의 투입에 의하여 수행되는 공정흑연을 이용한 그래핀 제조방법.The fifth step is to the input of at least one reducing agent of hydrazine, sodium hydride, hydroquinone, sodium borohydride, ascorbic acid and glucose (glucose) Graphene manufacturing method using a process graphite performed by.
  10. 제1항에 있어서,The method of claim 1,
    상기 제2단계 이후 상기 혼합물로부터 다이아몬드를 회수하는 회수단계를 더 포함하는 공정흑연을 이용한 그래핀 제조방법.Graphene manufacturing method using a process graphite further comprising a recovery step of recovering diamond from the mixture after the second step.
  11. 제10항에 있어서,The method of claim 10,
    상기 회수단계에서는 귀금속을 더 회수하는 공정흑연을 이용한 그래핀 제조방법.Graphene manufacturing method using the process graphite to further recover the precious metal in the recovery step.
  12. 제10항에 있어서,The method of claim 10,
    상기 회수 단계 이후 상기 혼합물 내의 흑연을 정제시키는 단계를 더 포함하는 공정흑연을 이용한 그래핀 제조방법.Graphene manufacturing method using the process graphite further comprising the step of purifying the graphite in the mixture after the recovery step.
  13. 제1항에 있어서,The method of claim 1,
    상기 제2단계 이후 상기 혼합물을 과산화수소(H2O2)처리하는 단계를 더 포함하는 공정흑연을 이용한 그래핀 제조방법.Graphene manufacturing method using a process graphite further comprising the step of treating the mixture with hydrogen peroxide (H 2 O 2 ) after the second step.
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