The method for manufacturing graphene from carbon by products and graphene manufactured using the same

Abstract

The present invention relates to a method for producing graphene from carbon byproducts and graphene produced therefrom. In one embodiment, the method for producing graphene from carbon byproducts comprises the steps of: producing micronized byproduct carbon containing carbon and metal by micronizing byproduct carbon; preparing a dispersion solution containing the micronized byproduct carbon and a solvent; and applying physical shear stress to the dispersion solution to exfoliate the micronized byproduct carbon and convert it into graphene.

Description

Technology Field

[0001] The present invention relates to a method for producing graphene from carbon byproducts and graphene produced therefrom. More specifically, the invention relates to a method for producing graphene that can recycle byproducts generated during the hydrogen production process as raw materials for graphene production, and graphene produced therefrom. Background Technology

[0003] Carbon byproducts are byproducts generated during the decomposition of hydrocarbon compounds, such as methane, particularly in hydrogen production processes.

[0004] Carbon byproducts typically contain a large amount of carbon, exceeding 70%, making them suitable for producing graphene-based materials. Generally, graphene-based materials include graphene, graphene oxide, reduced graphene oxide, or graphene-like materials.

[0005] In conventional physical processing methods using ball mills or ultrasound, graphite particles are micronized and homogenized, but it is difficult to achieve a high level of uniformity. Furthermore, the graphite layer exfoliation efficiency is very low, and there is a problem where the layer splits and shrinks. Therefore, it is difficult to manufacture high-quality mechanically exfoliated graphene with a nano-thick plate-like structure.

[0006] To exfoliate graphene from graphite, energy capable of overcoming the interactions between stacked graphene layers must be applied, and high-pressure homogenization is commonly used. High-pressure homogenization involves applying high shear force in the planar direction of the layers using a solvent with excellent surface wettability with carbon layers, which can produce nano-carbon that is physically thin and close to graphene.

[0007] Accordingly, the present invention developed a commercially more useful two-dimensional plate-like structure, namely nano-thick mechanically exfoliated graphene, by a method of micronizing carbon byproducts having a large secondary aggregate phase during a gas fluidization reaction process while simultaneously exfoliating a graphite layer containing a metal catalyst through high shear stress, and completed the present invention.

[0008] The background technology related to the present invention is disclosed in Korean Registered Patent Publication No. 10-2086764 (published on March 9, 2020, Title of Invention: Method for Manufacturing Graphene). The problem to be solved

[0010] One objective of the present invention is to provide a method for producing high-purity graphene uniformly dispersed to a nano-thickness from carbon byproducts.

[0011] Another objective of the present invention is to provide a method for manufacturing graphene with low defects and excellent electrical conductivity.

[0012] Another objective of the present invention is to provide a method for manufacturing graphene with excellent eco-friendliness by recycling carbon byproducts discarded in the hydrogen production process to prevent environmental pollution.

[0013] Another objective of the present invention is to provide a method for manufacturing graphene with excellent productivity and economic efficiency.

[0014] Another objective of the present invention is to provide graphene produced from the above graphene manufacturing method. means of solving the problem

[0016] One aspect of the present invention relates to a method for producing graphene from carbon byproducts. In one embodiment, the method for producing graphene from carbon byproducts comprises the steps of: producing micronized byproduct carbon containing carbon and metal by micronizing byproduct carbon; preparing a dispersion solution containing the micronized byproduct carbon and a solvent; and applying physical shear stress to the dispersion solution to exfoliate the micronized byproduct carbon to form graphene.

[0017] In one embodiment, the byproduct carbon may be generated in a hydrocarbon pyrolysis process for hydrogen production.

[0018] In one embodiment, the metal may include one or more of iron (Fe), nickel (Ni), titanium (Ti), and palladium (Pd).

[0019] In one embodiment, the micronized byproduct carbon may have an average size of 1 to 50 μm.

[0020] In one embodiment, the dispersion solution may contain 1 to 5 weight percent of micronized byproduct carbon.

[0021] In one embodiment, the solvent may include one or more of an aqueous solvent and a polar organic solvent.

[0022] In one embodiment, the dispersion solution further comprises a dispersant, and the dispersant may include one or more of sodium cholate (NaC), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polystyrene sulfonate (PSS), dodecylbenzene sulfonic acid (DBSA), and ionic liquid.

[0023] In one embodiment, the above-mentioned stripping can be carried out by introducing the dispersion solution into the inlet of a high-pressure homogenizer while applying a pressure of 100 to 3000 bar and passing it through a flow path.

[0024] In one embodiment, after the step of exfoliating the micronized byproduct carbon, the method may further include the step of recovering the graphene using one or more of centrifugation, vacuum filtration, and pressure filtration.

[0025] In one embodiment, the recovered graphene can be dried under vacuum and at a temperature of 30 to 200°C.

[0026] In one embodiment, after the step of recovering the graphene, the method may further include the step of heat-treating the recovered graphene.

[0027] Another aspect of the present invention relates to graphene produced by a method for producing graphene from the carbon byproduct.

[0028] In one embodiment, the graphene has a specific surface area (BET) of 20 m² 2 It has a thickness of 50 nm or less and contains metal.

[0029] In one embodiment, the metal may include one or more of iron (Fe), nickel (Ni), titanium (Ti), and palladium (Pd).

[0030] In one embodiment, the metal may have an average size of 1 nm to 5 mm. Effects of the invention

[0032] Graphene produced by the graphene manufacturing method according to the present invention enables the production of high-purity graphene uniformly dispersed to a nano thickness from carbon byproducts, has low defects and excellent electrical conductivity, prevents environmental pollution by recycling carbon byproducts discarded in the hydrogen production process, has excellent eco-friendliness, and can have excellent productivity and economic efficiency. Brief explanation of the drawing

[0034] FIG. 1 shows a method for producing graphene from carbon byproducts according to one embodiment of the present invention. Figure 2 is a scanning electron microscope (SEM) image showing the graphene of Example 1. Specific details for implementing the invention

[0035] In describing the present invention, if it is determined that a detailed description of related known technologies or configurations could unnecessarily obscure the essence of the invention, such detailed description will be omitted.

[0036] Furthermore, the terms described below are defined in consideration of their functions in the present invention; since these may vary depending on the intentions or practices of the user or operator, their definitions should be based on the content throughout this specification describing the present invention.

[0037] The present invention relates to a method for forming graphene, and specifically to a method for manufacturing graphene by using a physical method for separating a graphene film from byproduct carbon by shear stress. This process is referred to as exfoliation, peeling, stripping, or separation.

[0038] In one embodiment, the byproduct carbon may be generated from a hydrocarbon pyrolysis process for hydrogen production. Generally, since the hydrocarbon (methane) decomposition process for hydrogen production uses a metal catalyst, the resulting byproduct carbon may contain metal components. Therefore, the advantages of the method may include a step of forming functionalized graphene containing metal components.

[0039] The graphene manufacturing method of the present invention manufactures exfoliated graphene while substantially preserving the metal component. In contrast to conventional chemical-based processes in which the metal component is completely dissolved, the method disclosed herein enables the formation of exfoliated graphene while the metal component remains intact.

[0040] The method disclosed herein enables the graphene film to be peeled off from the metal component (i.e., stripping, separation, peeling, etc.) by using an organic solvent with excellent wettability with graphite or a solvent to which a dispersant capable of improving wettability is applied, while rotating a fluid containing byproduct carbon or passing it through a fine micro-nozzle, thereby generating a high shear force at the interface between the fluid and the reactor.

[0041] Therefore, graphene containing metal components having a surface-planarized carbon layer is produced, and high-purity graphene with small defects and high conductivity, uniformly dispersed to a nano-thickness, can be developed.

[0042] The graphene of the present invention may include one or more of graphene, graphene oxide, reduced graphene oxide, and similar graphene.

[0044] Method for producing graphene from carbon byproducts

[0045] One aspect of the present invention relates to a method for producing graphene from carbon byproducts. FIG. 1 illustrates a method for producing graphene from carbon byproducts according to one embodiment of the present invention. Referring to FIG. 1, the method for producing graphene from carbon byproducts comprises: (S10) a step of micronizing byproduct carbon; (S20) a step of preparing a dispersion solution; and (S30) a step of physical exfoliation.

[0046] More specifically, the method for manufacturing graphene from the carbon byproduct comprises: (S10) a step of micronizing byproduct carbon containing carbon and metal to produce micronized byproduct carbon; (S20) a step of preparing a dispersion solution containing the micronized byproduct carbon and a solvent; and (S30) a step of applying physical shear stress to the dispersion solution to exfoliate the micronized byproduct carbon to form graphene.

[0047] Hereinafter, a method for manufacturing graphene from the above-mentioned carbon byproduct will be described in detail step by step.

[0049] (S10) By-product carbon atomization step

[0050] The above step is a step of micronizing byproduct carbon containing carbon and metal.

[0051] The above by-product carbon may contain 5 to 95 weight% of carbon and 5 to 95 weight% of a chemical containing a metal. When included within the above content range, it may be possible to manufacture high-quality graphene with a high graphene yield and excellent mechanical properties and electrical conductivity. For example, the above by-product carbon may contain 80 to 90 weight% of carbon and 10 to 20 weight% of a metal.

[0052] The above byproduct carbon can be mixed with a solvent to form a mixture, and then micronized. For example, the mixture may contain 50 to 95 weight percent of byproduct carbon and 5 to 50 weight percent of solvent. Under these conditions, the mixability and dispersibility are excellent, and the micronization of the byproduct carbon can be easily achieved.

[0053] In one embodiment, the solvent may include one or more of water and alcohol-based solvents. For example, the alcohol-based solvent may include one or more of methanol, ethanol, isopropanol, and butanol.

[0054] The device for atomizing the above-mentioned byproduct carbon is not specifically limited, but, for example, a method using a high-hardness grinding medium such as a ball mill or an attrition mill may be used. Additionally, an ultrasonic device may be used, and any method or device commonly used for grinding may be suitably applied to the present invention and is not specifically limited thereto.

[0055] In one embodiment, the metal may include one or more of iron (Fe), nickel (Ni), titanium (Ti), and palladium (Pd).

[0056] In one embodiment, the micronized byproduct carbon may have an average size of 1 to 50 μm. The size may refer to the maximum length or diameter of the micronized byproduct carbon. Under these conditions, physical exfoliation of the byproduct carbon is easy, allowing for the easy production of graphene and minimization of defects. For example, the micronized byproduct carbon may have an average size of 20 μm or less.

[0058] (S20) Step for preparing dispersion solution

[0059] The above step is to prepare a dispersion solution containing micronized byproduct carbon and a solvent. The micronized byproduct carbon can be dispersed in the solvent to convert it into a form of dispersion solution (mixture) that is easily physically separated.

[0060] In one embodiment, the dispersion solution may contain 1 to 5 weight percent of micronized byproduct carbon. When included under these conditions, physical exfoliation is easy, so graphene can be easily manufactured.

[0061] In one embodiment, the solvent may include one or more of an aqueous solvent and a polar organic solvent. When the solvent is included, dispersibility and miscibility may be excellent. In one embodiment, the polar organic solvent may include one or more of N-methyl-2-pyrrolidone (NMP) and N,N-dimethylformamide (DMF). In the case of NMP and DMF, they have characteristics that have surface energy similar to graphene, so they have excellent miscibility and dispersibility and are easy to physically exfoliate, allowing for easy preparation of graphene.

[0062] In one embodiment, the dispersion solution may further include a dispersant. For example, the dispersant may include one or more of sodium cholate (NaC), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polystyrenesulfonate (PSS), dodecylbenzene sulfonic acid (DBSA), and ionic liquid. When the dispersant is included, the mixability and dispersibility are excellent, and the exfoliation efficiency of graphite-based materials is excellent, allowing graphene to be easily manufactured.

[0064] (S30) Physical peeling step

[0065] The above step is a step of applying physical shear stress to the dispersion solution to exfoliate the micronized byproduct carbon and graphene it.

[0066] A graphene dispersion solution with a large area and low defects can be prepared by exfoliating and dispersing the byproduct carbon in a solvent through an exfoliation method that applies physical shear stress to the above byproduct carbon mixture (dispersion solution). Here, a homogenizer or a high-pressure homogenizer, where shear stress is mainly applied, can be used as the method for applying physical shear stress.

[0067] The exfoliation method of byproduct carbon using shear stress can separate graphene from byproduct carbon non-destructively compared to the conventional exfoliation method using ultrasonic grinding. In addition, the exfoliation state of byproduct carbon using the shear stress can be controlled by process conditions such as time, pressure, and rotation RPM. The above process conditions, etc., can be selected from conditions typically performed in the graphene manufacturing process and are not specifically limited here.

[0068] In one embodiment, the exfoliation can be carried out by introducing the dispersion solution into the inlet of a high-pressure homogenizer while applying a pressure of 100 to 3000 bar and passing it through a microchannel. Under these pressure conditions, a high shear force is applied to the byproduct carbon in the dispersion solution, allowing it to be easily exfoliated and graphene-formed.

[0069] For example, the process of applying pressure to the above dispersion solution and introducing it into the high-pressure homogenizer inlet and passing through the microchannel can be repeated two or more times.

[0071] (S40) Graphene recovery step

[0072] In one embodiment, after the step of exfoliating the micronized byproduct carbon, the method may further include the step of recovering the graphene using one or more of centrifugation, vacuum filtration, and pressure filtration.

[0073] In one embodiment, the recovered graphene can be dried under vacuum and conditions of 30 to 200°C. Under these conditions, the drying efficiency may be excellent.

[0074] The recovered graphene itself can be used as is, but a heat treatment method can be used to improve its original electrical and physical properties.

[0076] (S50) Heat treatment step

[0077] In one embodiment, after the step of recovering the graphene, the method may further include a step of heat-treating the recovered graphene. For example, the heat treatment may be performed at 500 to 5000°C. Under these conditions, the electrical conductivity of the graphene can be excellent while minimizing defects.

[0079] Graphene produced by a method for manufacturing graphene from carbon byproducts

[0080] Another aspect of the present invention relates to graphene produced by a method for producing graphene from the carbon byproduct.

[0081] In one embodiment, the graphene has a specific surface area (BET) of 20 m² 2 It has a specific surface area of ​​1 / g or more and an average thickness of 50 nm or less, and contains metal. Under the above specific surface area and thickness conditions, the mechanical strength and electrical conductivity of the graphene can be excellent. For example, the graphene has a specific surface area (BET) of 20 to 60 m² 2 / g and average thickness can be 1~50nm or 10~50nm.

[0082] In one embodiment, the graphene may contain 5 to 95 weight% of carbon and 5 to 95 weight% of a chemical containing a metal. When included within the above content range, the mechanical properties and electrical conductivity of the graphene may be excellent. For example, the graphene may contain 80 to 90 weight% of graphene and 10 to 20 weight% of a metal.

[0083] In one embodiment, the metal may include one or more of iron (Fe), nickel (Ni), titanium (Ti), and palladium (Pd).

[0084] In one embodiment, the metal may have an average size of 1 nm to 5 mm. The average size may refer to the maximum length or diameter of the metal.

[0085] In one embodiment, the metal may be dispersed between the graphene layers. For example, the metal may be inserted between the graphene layers.

[0086] The graphene produced above can be utilized in various fields, such as electrode materials for energy storage devices, heat dissipation, and composite materials.

[0088] Hereinafter, the structure and operation of the present invention will be explained in more detail through preferred embodiments. However, these are presented as preferred examples of the present invention and should not be interpreted in any way as limiting the present invention. Details not described herein can be sufficiently technically inferred by those skilled in the art, so such descriptions will be omitted.

[0090] Examples and Comparative Examples

[0091] Example 1

[0092] A mixture was prepared by mixing byproduct carbon containing 80 wt% carbon and 20 wt% of a chemical containing a metal in an ethanol solvent. The mixture contained 90 wt% byproduct carbon and 10 wt% ethanol. The mixture was pulverized using an attrition mill for 12 hours to control the byproduct carbon to a uniform particle size of an average size of 10 μm or less. A dispersion solution was prepared by mixing 2 wt% of the pulverized byproduct carbon and 98 wt% of a mixed solvent (NMP) and dispersing it using a homogenizer at 1500 rpm for 1 hour.

[0093] Subsequently, the dispersion solution was introduced into the inlet of a high-pressure homogenizer at a high pressure of approximately 1000 bar and passed through a microchannel, and this process was repeated three times. Through this, the byproduct carbon was exfoliated and graphene was produced, thereby manufacturing graphene containing metal components. The graphene was recovered using one or more of centrifugation, vacuum filtration, and pressure filtration, and the graphene was dried under vacuum and at a temperature of 30 to 200°C.

[0094] Figure 2 is a scanning electron microscope (SEM) image showing the graphene of Example 1. Referring to Figure 2, the specific surface area of ​​the exfoliated graphene in Example 1 was measured using a BET device and found to be 36.7 m² 2 It was confirmed that graphene with a thickness of 23.7 nm was produced at / g.

[0096] Example 2

[0097] Graphene was prepared using the same method as in Example 1, except that the graphene was heat-treated at 4000–5000°C. The specific surface area of ​​the heat-treated graphene in Example 2 was measured using a BET device, and the result was 25.7 m². 2 It was confirmed that graphene with a thickness of 33.98 nm was produced as / g.

[0098] The present invention reduces costs during graphene manufacturing by recycling byproduct carbon, which is a byproduct discarded during the hydrogen production process, and uses it as a raw material for graphene, and has the effect of reducing additional costs such as waste disposal costs for disposing of byproduct carbon.

[0099] In addition, according to the present invention, by recycling byproduct carbon, which is a byproduct discarded after the hydrogen production process, environmental pollution problems occurring during the disposal process can be minimized, thereby providing an eco-friendly effect.

[0101] The present invention has been described above with reference to embodiments. Those skilled in the art will understand that the present invention may be embodied in modified forms without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the invention is defined by the claims, not by the foregoing description, and all variations within the scope of equivalents should be interpreted as being included in the invention.

Claims

Claim 1 A method for producing graphene from carbon byproducts, comprising: a step of producing micronized byproduct carbon by micronizing byproduct carbon containing 80-90 wt% carbon and 10-20 wt% metal; a step of preparing a dispersion solution containing the micronized byproduct carbon and a solvent; and a step of exfoliating the micronized byproduct carbon to graphene by applying physical shear stress to the dispersion solution; wherein the byproduct carbon is generated from a hydrocarbon pyrolysis process for hydrogen production, and the metal includes one or more of iron (Fe), nickel (Ni), titanium (Ti), and palladium (Pd). Claim 2 delete Claim 3 delete Claim 4 In claim 1, the method for producing graphene from carbon byproducts having an average size of 1 to 50 μm, wherein the micronized byproduct carbon is used. Claim 5 In claim 1, the dispersion solution comprises 1 to 5 weight percent of micronized by-product carbon, a method for producing graphene from carbon by-products. Claim 6 A method for producing graphene from carbon byproducts according to claim 1, wherein the solvent comprises one or more of an aqueous solvent and a polar organic solvent. Claim 7 A method for producing graphene from carbon byproducts according to claim 1, wherein the dispersion solution further comprises a dispersant, and the dispersant comprises one or more of sodium cholate (NaC), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polystyrene sulfonate (PSS), dodecylbenzene sulfonic acid (DBSA), and ionic liquid. Claim 8 A method for producing graphene from carbon byproducts according to claim 1, wherein the exfoliation is carried out by introducing the dispersion solution into the inlet of a high-pressure homogenizer while applying a pressure of 100 to 3000 bar and passing it through a flow path. Claim 9 A method for producing graphene from carbon byproducts according to claim 1, further comprising the step of recovering the graphene using one or more of centrifugation, vacuum filtration, and pressure filtration after the step of exfoliating the micronized byproduct carbon. Claim 10 In claim 9, the method for producing graphene from carbon byproducts, wherein the recovered graphene is dried under vacuum and conditions of 30 to 200°C. Claim 11 A method for producing graphene from carbon byproducts according to claim 9, further comprising the step of heat-treating the recovered graphene after the step of recovering the graphene. Claim 12 A graphene produced by a method for producing graphene from a carbon byproduct according to any one of claims 1, 4 to 11, comprising 80 to 90 weight% graphene and 10 to 20 weight% metal, wherein the metal comprises one or more of iron (Fe), nickel (Ni), titanium (Ti), and palladium (Pd), and having a specific surface area (BET) of 20 m² 2 Graphene having a g or greater and an average thickness of 1 to 50 nm. Claim 13 delete Claim 14 delete Claim 15 In paragraph 12, the metal is graphene having an average size of 1 nm to 5 mm.

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