Method for producing graphene analogs using metallurgical coke powder

Abstract

The present invention relates to a method for producing a graphene analogue using metallurgical coke powder, which includes processes such as crushing and screening, high-pressure extraction, chemical oxidation, solid-phase reduction, and solvent exfoliation. According to the present invention, the problem of highly valuably utilizing the coke powder of coke manufacturing enterprises is solved. The obtained graphene analogue has a uniform shape and size distribution, and moreover, the impurity content is extremely low. It has been developed as an inexpensive and easily available production raw material for the production of graphene, which can not only reduce production costs but also shorten the production period.

Description

[Technical Field]

[0001] The present invention relates to the technical field for the production of graphene materials, and more particularly to a method for producing graphene analogs using metallurgical coke powder. [Background technology]

[0002] Carbon-based nanomaterials have attracted widespread attention in recent years due to their unique physical, chemical, electronic, and mechanical properties, and are used as key components in fuel cells, biosensors, catalysts, batteries, and electronic devices. The oldest nanomaterial synthesis techniques used expensive carbon precursors such as high-purity graphite, but natural graphite reserves are extremely low, and the production cost of synthetic graphite is high. Currently, technologies are being developed to synthesize carbon-based nanomaterials using relatively inexpensive coal or abundant biomass resources, but when using coal or biomass as raw materials, the degree of orderliness of the matrix carbon structure is poor, and further high-temperature processing is required to meet the requirements for use.

[0003] Methods for producing graphene from coal as a raw material mainly include chemical vapor deposition (CVD), arc discharge, oxidation-extraction (OCE), chemical leaching, template formation, heat treatment, dielectric barrier discharge (DBD) plasma, and hydrazine chemical oxidation-reduction. Among these, the chemical route (oxidation and subsequent reduction) and the physical route (solvent exfoliation), which are simpler to operate, are the most commonly used methods.

[0004] Metallurgical coke powder (particle size <5 mm) is one of the by-products of the coke manufacturing process, often generated during the coke crushing process, and accounts for 4% of metallurgical coke products. The coke matrix is ​​characterized by a turbine layer structure formed by the deposition of simple hexagonal crystals of approximately 1 nm, and contains small amounts of dispersed minerals. Before blast furnace ironmaking, in the carbonization process at coking temperatures of 900-1100°C, carbon of various sizes is reoriented, aligning locally in parallel. This process is also called graphitization. To date, coke powder has been applied to industrial production such as blowing into blast furnaces, blending into sintered coal, and exhaust gas treatment materials, but research on the comprehensive utilization of coke powder as a whole is still in the low value-added stage. Therefore, providing low-cost novel carbon materials, lithium battery anode materials, and nanomaterials for large-scale production using coke powder is of great importance.

[0005] A Chinese patent application with application number CN201911071952.1 discloses a method for producing a graphene analog material using biomass waste and its application, which involves heating and calcining biomass waste at 600-1500°C for 1-5 hours under the protection of a protective gas to obtain a carbonized biomass material; stirring and mixing the carbonized biomass material with an activator, drying it, and further calcining it at 400-1500°C for 1-5 hours under the protection of a protective gas to obtain an activated mixture; placing the activated mixture in a hydrothermal reactor to which an acid solution is added and reacting it at 120-220°C for 6-12 hours to obtain a hydrothermally oxidized mixture; washing the hydrothermally oxidized mixture and performing ultrasonic peeling to obtain a dispersion of biomass-based graphene analog material; and freeze-drying the dispersion of biomass-based graphene analog material to obtain a biomass-based graphene analog material. This method primarily uses biomass as a raw material, but it has several drawbacks: 1) the fixed carbon content of biomass is extremely low, while the volatile and ash content is high, resulting in significant influence from impurities during processing; and 2) the carbon structure of biomass is highly irregular, requiring multiple high-temperature calcinations to obtain an ideal graphene structure, making the process complicated and significantly increasing processing costs.

[0006] A Chinese patent application with application number CN202110175216.1 discloses a "method for producing a lignite-based graphene analog and its application," which involves extracting lignite with a strong alkaline weak salt, and obtaining a lignite-based graphene analog by hydrothermal treatment, activation, pickling, and drying of the extracted liquid phase product. The morphology of the lignite-based graphene analog is adjusted and controlled by adjusting and controlling conditions such as the type and concentration of the mixed solution, hydrothermal temperature and time, and activation temperature and time. This method removes impurities from the lignite with an inorganic salt solution, but this hinders the efficiency of subsequent oxidation and activation. Furthermore, because the water washing process needs to be repeated multiple times to achieve optimal effects in the extraction and pickling processes, the processing time and cost increase significantly.

[0007] The article "Progress in Research on the Production of Coal-Based Graphene, a New Coal-Based Material, and its Application in the Field of Thermal Conductivity" ("Coal Science Bulletin," Vol. 45, No. 1, January 2020) states that "coal-based graphene is graphene converted from coal as a raw material, and after high-temperature heat treatment, coal-based graphene is obtained by the conventional graphene manufacturing method." However, the heat treatment process of the raw coal requires high temperatures up to 2000°C and a well-sealed environment, and the treatment of raw coal has drawbacks such as insufficient removal of impurities and low quality of coal-based graphene, making it impractical. [Overview of the project] [Problems that the invention aims to solve]

[0008] The present invention solves the problem of coke manufacturers in utilizing coke powder in a high-value-added way, and provides a method for producing a graphene analog using metallurgical coke powder that can be developed as an inexpensive and readily available raw material for the manufacture of graphene, with a uniform distribution of shape and size, and an extremely low impurity content, thereby reducing production costs and shortening production time. [Means for solving the problem]

[0009] To achieve the above objective, the present invention employs the following technical means. A method for producing a graphene analog using metallurgical coke powder, including the following steps. 1) A crushing and sieving process in which metallurgical coke powder is polished and sieved to obtain ultrafine coke powder with a particle size of 20 μm or less, 2) A high-pressure extraction process in which ultrafine coke powder and an extractant are placed in a high-pressure reactor and subjected to high-pressure extraction under a protective atmosphere, and further subjected to centrifugation, rotary evaporation, and drying to obtain ultra-high-purity carbon, 3) A chemical oxidation process to obtain a carbon oxide material by reacting ultra-high purity carbon with a strong oxidizing agent, 4) A solid-phase reduction step in which a carbon oxide material is reduced at high temperature to obtain an activated graphene analog precursor material, 5) Possesses graphene analog precursor material machine A solvent exfoliation step in which graphene analogs are obtained by exfoliating in a solvent.

[0010] Furthermore, in step 1) above, the particle size of the metallurgical coke powder is less than 5 mm, polishing is performed using a high-energy planetary ball mill, the ball milling time is 6 to 12 hours, the ball milling speed is 50 to 200 r / min for the orbital speed and 200 to 400 r / min for the rotational speed, the material of the ball mill tank is stainless steel, and the material of the milling balls is zirconia.

[0011] Furthermore, in step 2), the solid-liquid ratio of ultrafine coke powder to extractant is 1:20 to 1:50, and the extractant is one of the following: (1) N-methylpyrrolidone as a single solvent, (2) A mixed solvent of n-hexane and N-methylpyrrolidone in a volume ratio of 1:1 to 5:1, (3) A mixed solvent of tetrahydrofuran and N-methylpyrrolidone in a volume ratio of 1:1 to 5:1.

[0012] Furthermore, in step 2), the conditions for the high-pressure extraction process are as follows: the extraction temperature is 200 to 400°C and maintained at a constant temperature for 1 to 6 hours; the pressure during the extraction process is 0.4 to 5.0 MPa; the mixture of ultrafine coke powder and extractant is stirred at a stirring speed of 200 to 600 r / min during the extraction process; and the protective atmosphere is high-purity N2 or high-purity Ar.

[0013] Furthermore, in step 2), the centrifugation, rotary evaporation, and drying are performed by separating the solid and liquid phases using centrifugation, removing the solvent from the separated liquid phase using rotary evaporation, washing the solid obtained by rotary evaporation, and then drying it in a vacuum oven at a temperature of 55-75°C for 12-24 hours.

[0014] Furthermore, in step 3), the mixing ratio of ultra-high purity carbon to strong oxidizing agent is 1:1:5 to 1:1:9, where ultra-high purity carbon:sodium nitrate:potassium permanganate. Furthermore, the operational process of step 3) involves mixing ultra-high purity carbon and a strong oxidizing agent in an ice bath, reacting under stirring for 10-30 minutes while controlling the reaction temperature to 20°C or below, then raising the temperature to 30-40°C and stirring for another 25-60 minutes; then gradually adding deionized water in a 1:1 volume ratio, and after 15-25 minutes adding hydrogen peroxide to reduce the remaining oxidizing agent and turn the solution bright yellow; filtering while hot, washing with a 5% HCl solution and deionized water until no sulfate groups are detected in the filtrate; and finally drying the filtered cake in a vacuum oven at 50-80°C to obtain the carbon oxide material.

[0015] Furthermore, in step 4), the solid-phase reduction is carried out at a temperature of 1000°C to 1200°C for 1 to 3 hours under a protective atmosphere, and the protective gas is high-purity N2 or high-purity Ar. Furthermore, in step 5), the solvent exfoliation specifically involves dispersing the graphene analog precursor material in a 1 mg / mL N-methylpyrrolidone solution, sonicating it at a temperature of 50-70°C for 3-6 hours, and then rotating the resulting solution to finally obtain the graphene analog. [Effects of the Invention]

[0016] The present invention has the following beneficial effects compared with the prior art. 1) It can solve the problem of utilizing coke powder from coke manufacturing enterprises with high added value. 2) It can develop inexpensive and easily available production raw materials for the production of graphene, not only reducing production costs but also shortening the production period. 3) The graphene analog obtained by the method according to the present invention has a uniform shape and size distribution. Also, since the impurity content is extremely low, it does not affect the local structure of the graphene analog material.

Brief Description of the Drawings

[0017] [Figure 1] It is a flowchart of a method for manufacturing a graphene analog using metallurgical coke powder according to the present invention. [Figure 2] It is a comparison diagram of X-ray photoelectron spectroscopy (XPS) before and after the treatment of ultrafine coke powder in Example 1. [Figure 3] It is a comparison diagram of Raman spectra before and after the treatment of ultrafine coke powder in Example 1. [Figure 4] It is a comparison diagram of X-ray diffraction (XRD) patterns before and after the treatment of ultrafine coke powder in Example 1. [Figure 5] It is a comparison diagram of transmission electron microscope (TEM) images before and after the treatment of ultrafine coke powder in Example 1.

Modes for Carrying Out the Invention

[0018] Hereinafter, specific embodiments of the present invention will be further described based on the drawings. As shown in FIG. 1, the method for manufacturing a graphene analog using metallurgical coke powder according to the present invention includes the following steps. 1) A crushing and sieving step of polishing and sieving metallurgical coke powder to obtain ultrafine coke powder with a particle size of 20 μm or less, 2) A high-pressure extraction process in which ultrafine coke powder and an extractant are placed in a high-pressure reactor and subjected to high-pressure extraction under a protective atmosphere, and further subjected to centrifugation, rotary evaporation, and drying to obtain ultra-high-purity carbon, 3) A chemical oxidation process to obtain a carbon oxide material by reacting ultra-high purity carbon with a strong oxidizing agent, 4) A solid-phase reduction step in which a carbon oxide material is reduced at high temperature to obtain an activated graphene analog precursor material, 5) Possesses graphene analog precursor material machine A solvent exfoliation step in which graphene analogs are obtained by exfoliating in a solvent.

[0019] Furthermore, in step 1) above, the particle size of the metallurgical coke powder is less than 5 mm, polishing is performed using a high-energy planetary ball mill, the ball milling time is 6 to 12 hours, the ball milling speed is 50 to 200 r / min for the orbital speed and 200 to 400 r / min for the rotational speed, the material of the ball mill tank is stainless steel, and the material of the milling balls is zirconia.

[0020] Furthermore, in step 2), the solid-liquid ratio of ultrafine coke powder to extractant is 1:20 to 1:50, and the extractant is one of the following: (1) N-methylpyrrolidone as a single solvent, (2) A mixed solvent of n-hexane and N-methylpyrrolidone in a volume ratio of 1:1 to 5:1, (3) A mixed solvent of tetrahydrofuran and N-methylpyrrolidone in a volume ratio of 1:1 to 5:1.

[0021] Furthermore, in step 2), the conditions for the high-pressure extraction process are as follows: the extraction temperature is 200 to 400°C and maintained at a constant temperature for 1 to 6 hours; the pressure during the extraction process is 0.4 to 5.0 MPa; the mixture of ultrafine coke powder and extractant is stirred at a stirring speed of 200 to 600 r / min during the extraction process; and the protective atmosphere is high-purity N2 or high-purity Ar. Furthermore, in step 2), the centrifugation, rotary evaporation, and drying are performed by separating the solid and liquid phases using centrifugation, removing the solvent from the separated liquid phase using rotary evaporation, washing the solid obtained by rotary evaporation, and then drying it in a vacuum oven at a temperature of 55-75°C for 12-24 hours.

[0022] Furthermore, in step 3), the mixing ratio of ultra-high purity carbon to strong oxidizing agent is 1:1:5 to 1:1:9, where ultra-high purity carbon:sodium nitrate:potassium permanganate. Furthermore, the operational process of step 3) involves mixing ultra-high purity carbon and a strong oxidizing agent in an ice bath, reacting under stirring for 10-30 minutes while controlling the reaction temperature to 20°C or below, then raising the temperature to 30-40°C and stirring for another 25-60 minutes; then gradually adding deionized water in a 1:1 volume ratio, and after 15-25 minutes adding hydrogen peroxide to reduce the remaining oxidizing agent and turn the solution bright yellow; filtering while hot, washing with a 5% HCl solution and deionized water until no sulfate groups are detected in the filtrate; and finally drying the filtered cake in a vacuum oven at 50-80°C to obtain the carbon oxide material.

[0023] Furthermore, in step 4), the solid-phase reduction is carried out at a temperature of 1000°C to 1200°C for 1 to 3 hours under a protective atmosphere, and the protective gas is high-purity N2 or high-purity Ar. Furthermore, in step 5), the solvent exfoliation specifically involves dispersing the graphene analog precursor material in a 1 mg / mL N-methylpyrrolidone solution, sonicating it at a temperature of 50-70°C for 3-6 hours, and then rotating the resulting solution to finally obtain the graphene analog.

[0024] The method for producing a graphene analog using metallurgical coke powder according to the present invention includes steps such as crushing and sieving, high-pressure extraction, chemical oxidation, solid-phase reduction, and solvent exfoliation. The specific process is as follows.

[0025] 1. Crushing and sieving: Metallurgical coke powder is polished using a high-energy planetary ball mill. The ball mill tank is made of stainless steel, the milling balls are made of zirconia, the ball milling time is 6-12 hours, and the ball milling speed is 50-200 r / min for the orbital speed and 200-400 r / min for the rotational speed. After sieving, ultrafine coke powder with a particle size of 20 μm or less is obtained. The purpose of producing ultrafine coke powder is to increase the contact area in subsequent physical and chemical processing processes and improve processing efficiency.

[0026] 2. High-pressure extraction: The above-mentioned ultrafine coke powder is mixed with an extractant. Any of the following may be used as the extractant. (1) A single solvent of N-methylpyrrolidone with a solid-liquid ratio of 1:20 to 1:50, (2) A mixed solvent of n-hexane (HXN) and N-methylpyrrolidone in a volume ratio of 1:1 to 5:1. (3) A mixed solvent of tetrahydrofuran (THF) and N-methylpyrrolidone in a volume ratio of 1:1 to 5:1.

[0027] Ultrafine coke powder and extractant are placed in a high-pressure reactor in a solid-liquid ratio of 1:30 to 1:50, heated to a target temperature of 200 to 400°C under a protective atmosphere, and then kept at a constant temperature for 1 to 6 hours. During the heating process, the pressure is kept at 0.4 to 5.0 MPa, and the mixture is stirred with a stirring device at a stirring speed of 200 to 600 r / min. After the heated mixture has cooled naturally to room temperature, it is removed and the solid-liquid phase is separated by centrifugation. The solvent is removed from the separated liquid phase by rotary evaporation, and the solvent is recycled. The solid obtained by rotary evaporation is repeatedly washed with fresh solvent or deionized water, and then dried in a vacuum oven at 55 to 75°C for 12 to 24 hours to obtain ultra-high purity carbon. In this process, machine By extracting ultrafine coke powder at high temperature and pressure using a solvent, impurities in the ultrafine coke powder are separated from the carbon.

[0028] 3. Chemical oxidation: Place ultra-high purity carbon, sodium nitrate (NaNO3), and potassium permanganate (KMNO4) in a reaction bottle in a ratio of 1:1:5 to 1:1:9, mix in an ice bath, and react for 10 to 30 minutes with stirring while controlling the reaction temperature to below 20°C. Then raise the temperature to 30 to 40°C and stir for a further 25 to 60 minutes. Next, gradually add deionized water in a 1:1 volume ratio, and after 15 to 25 minutes, add hydrogen peroxide to reduce the remaining oxidizing agent and turn the solution bright yellow. Filter while hot and wash with a 5% HCl solution and deionized water until no sulfate groups are detected in the filtrate. Finally, thoroughly dry the filtered cake in a vacuum oven at 50 to 80°C to obtain the carbon oxide material. In this process, graphite is oxidized with a strongly acidic medium to break its II-conjugated structure and introduce oxygen-containing functional groups (e.g., hydroxyl groups, ketone groups, ether bonds, etc.) between the graphite layers. This weakens the van der Waals forces between the layers, resulting in graphite oxide with a relatively regular structure.

[0029] 4. Solid-phase reduction: The obtained carbon oxide material is activated at 1000°C to 1200°C for 1 to 3 hours in a furnace with a high-temperature atmosphere filled with high-purity N2 or high-purity Ar to obtain an activated graphene analog precursor material. By removing oxygen-containing functional groups between graphite layers through high-temperature reduction, a pure graphite sheet layer is obtained.

[0030] 5. Solvent exfoliation: The graphene analog precursor material is dispersed in a 1 mg / mL N-methylpyrrolidone (NMP) solution and sonicated at a temperature of 50-70°C for 3-6 hours. The graphene analog precursor material has machine It can be dispersed more effectively in the solvent. Next, the resulting solution is rotated and evaporated to finally obtain the graphene analog. [Examples]

[0031] The following embodiments are carried out based on the technical means of the present invention and illustrate detailed embodiments and specific operating procedures, but do not limit the scope of protection of the present invention. Example 1 In this example, a graphene analog was produced using metallurgical coke powder from a coke manufacturing company. The specific operating procedure was as follows.

[0032] 1. Crushing and sieving: Metallurgical coke powder was ball-milled using a high-energy planetary ball mill. The ball milling time was 6 hours, and the ball milling speed was set to an orbital speed of 100 r / min and a rotational speed of 200 r / min. After sieving, ultrafine coke powder with a particle size of 10 μm or less was obtained.

[0033] 2. High-pressure extraction: Using N-methylpyrrolidone (NMP) as the sole solvent extractant, the above-mentioned ultrafine coke powder and extractant were placed in a high-pressure reactor in a solid-liquid ratio of 1:40. Under a high-purity argon atmosphere, the mixture was heated to a target temperature of 350°C and then kept at a constant temperature for 3 hours. During the heating process, the pressure was maintained at 3.0 MPa and the stirring speed was set to 300 r / min. After natural cooling to room temperature, the mixture was removed and solid-liquid separation was performed using a centrifuge. The solvent was removed from the separated liquid phase by rotary evaporation, and the solvent was recycled. The solid obtained by rotary evaporation was repeatedly washed with deionized water, and then vacuum-dried in a vacuum oven at 70°C for 24 hours to obtain ultra-high-purity carbon.

[0034] 3. Chemical oxidation: Ultra-high purity carbon, sodium nitrate (NaNO3), and potassium permanganate (KMNO4) were placed in a 1:1:7 ratio in a 500 ml reaction bottle and mixed in an ice bath. The reaction was carried out for 25 minutes with stirring while controlling the reaction temperature to 18°C. Then the temperature was raised to 35°C and stirred for another 30 minutes. Next, deionized water was gradually added in a 1:1 volume ratio. After 20 minutes, hydrogen peroxide was added to reduce the remaining oxidizing agent, turning the solution a bright yellow. The solution was filtered while still hot, and the filtrate was repeatedly washed with a 5% HCl solution and deionized water until no sulfate groups were detected in the filtrate. Finally, the filtered cake was thoroughly dried in a vacuum oven at 60°C to obtain the carbon oxide material.

[0035] 4. Solid-phase reduction: The obtained carbon oxide material was activated at 1100°C for 1.5 hours in a furnace with a high-temperature atmosphere filled with protective gas to obtain an activated graphene analog precursor material. 5. Solvent exfoliation: The graphene analog precursor material was dispersed in a 1 mg / mL N-methylpyrrolidone (NMP) solution, sonicated at 60°C for 6 hours, and then the resulting solution was rotated and evaporated to finally obtain the graphene analog.

[0036] The graphene analog obtained in this embodiment has an extremely low impurity content, and the carbon powder obtained by high-pressure extraction with an organic solvent and rotational evaporation has an ash content of less than 1%, which does not affect the local structure of the graphene analog material. Furthermore, the structure of the graphene analog obtained in this embodiment was analyzed using methods such as Raman spectroscopy, transmission electron microscopy, XPS, and XRD. Figure 2 shows the ultrafine coke powder. Chemical oxidation This is a comparison diagram of the X-ray photoelectron spectra (XPS) before and after processing. Chemical oxidation Processed ultrafine coke powder teeth This indicates a significant increase in the number of acidic functional groups due to the oxidative action of NaNO3 and KMnO4. Due to the high number of oxygen-containing functional groups, the C / O ratio of the ultrafine carbon powder decreased from approximately 4.2 before treatment to approximately 1.9 after treatment. When the information hidden in C1s was deciphered by the peak separation method, sp in the coke powder after treatment was found to be 2 The percentage of hybridized carbon atoms reached 81.76%, which was higher than the 60.66% before treatment.

[0037] Figure 3 shows a comparison of Raman spectra before and after treatment of ultrafine coke powder. Both Raman spectra before and after treatment of the ultrafine coke powder show sp in graphite. 3 Defects and sp 2 Each of these represents a broad D-band (maximum 1350 cm) that shows a highly advanced graphitized structure. -1 ) and G-band (maximum 1580cm) -1 This indicates that the coke powder after processing has a weaker D band and a stronger G band at 2700 cm². -1 The more pronounced symmetrical peak at this point indicates that the resulting product consists of multiple layers of graphene sheets and has fewer defects. The width of its maximum band is relatively narrow (40 cm). -1) is a 14 cm² highly oriented pyrolytic graphite that is generally used as a near-perfect graphite. -1 It is significantly wider than that. When structural information hidden in the overlapping region of the G-band and D-band was identified using the deconvolution method developed by ACFerrari et al., the sample showed an improvement in graphitization, as the ID / IG ratio decreased from 1.074 to 0.607 after chemical and physical combined treatment, and the IV / IG ratio decreased from 0.975 to 0.423, indicating that various non-graphite structures were converted to graphite structures.

[0038] Figure 4 shows a comparison of X-ray diffraction (XRD) patterns of ultrafine coke powder before and after treatment. In the XRD pattern of coke before treatment, the (002) diffraction line shows a broad peak of medium intensity around 26°, and d002 calculated by Bragg's law is approximately 0.48 nm, indicating a low-order crystalline structure. After chemical and physical treatment, the (002) diffraction line is sharper, indicating that the size of the microcrystalline graphite grew in the Lc direction. The calculation results also show that Lc increased from 2.683 nm to 8.224 nm and La increased from 4.91 nm to 5.911 nm. The manufacturing method in this embodiment mainly involves chemical and physical methods that change the degree of orderliness of the carbon structure of the carbon groups, thereby changing the regular structure into a highly regular structure.

[0039] Figure 5 shows a comparison of transmission electron microscope (TEM) images of fine coke powder before and after treatment. Observations revealed that the coke sample showed no significant nanostructure changes before treatment, with a highly irregular carbon structure and no polyaromatic layer. After oxidation, thermal exfoliation, and solvent exfoliation, nanostructures were present, exhibiting the characteristic wrinkled appearance of graphene material. The treated sample had a uniform shape and size distribution, with a diameter of 3.61 ± 0.25 nm, and was nearly unoriented. Evidence of hexagonal crystal formations in the TEM images and an increase in the size of the polyaromatic layer, as shown in the Raman spectrum, demonstrates the presence of graphene in the product.

[0040] Table 1 shows a comparison of the performance of the carbon material in Example 1 before and after treatment.

[0041] [Table 1]

[0042] Example 2 In this example, a graphene analog was produced using metallurgical coke powder from a steel mill. The specific procedure was as follows.

[0043] 1. Crushing and sieving: Metallurgical coke powder was ball-milled using a high-energy planetary ball mill. The ball milling time was 6 hours, and the ball milling speed was set to an orbital speed of 50 r / min and a rotational speed of 300 r / min. After sieving, ultrafine coke powder with a particle size of 5 μm or less was obtained.

[0044] 2. High-pressure extraction: A mixed solvent of tetrahydrofuran (THF) and N-methylpyrrolidone was used as the extractant. The ultrafine coke powder and the extractant were placed in a high-pressure reactor in a solid-liquid ratio of 1:40 and heated to a target temperature of 380°C under a high-purity argon atmosphere, then kept at a constant temperature for 5 hours. During the heating process, the pressure was maintained at 4.0 MPa and the stirring speed was 600 r / min. After natural cooling to room temperature, the mixture was removed and solid-liquid separation was performed using a centrifuge. The solvent was removed from the separated liquid phase by rotary evaporation, and the solvent was recycled. The solid obtained by rotary evaporation was repeatedly washed with deionized water, and then vacuum-dried in a vacuum oven at 70°C for 12 hours to obtain ultra-high-purity carbon.

[0045] 3. Chemical acidification: Ultra-high purity carbon, sodium nitrate (NaNO3), and potassium permanganate (KMnO4) were put into a 500 ml reaction flask at a ratio of 1:1:7, mixed in an ice bath, and reacted with stirring for 18 min while controlling the reaction temperature at 16 °C. Then, the temperature was raised to 30 °C and stirred for another 60 min. Next, deionized water was gradually added at a volume ratio of 1:1. After 25 min, hydrogen peroxide solution was added to reduce the remaining oxidant, turning the solution into a bright yellow color. It was filtered while it was hot, and repeatedly washed with 5% HCl solution and deionized water until no sulfate group was detected in the filtrate. Finally, the filter cake was dried thoroughly in a vacuum oven at 80 °C to obtain the carbon oxide material.

[0046] 4. Solid-phase reduction: In a furnace with a high-temperature atmosphere filled with a protective gas, the obtained carbon oxide material was activated at 1150 °C for 3 h to obtain an activated graphene-like precursor material. 5. Solvent exfoliation: The graphene-like precursor material was dispersed in an N-methylpyrrolidone (NMP) solution with a concentration of 1 mg / mL, and ultrasonicated at 70 °C for 6 h. Then, the obtained solution was rotary evaporated to finally obtain the graphene-like material.

[0047] In the graphene-like material obtained in this example, the impurity content is extremely low (less than 0.02%), which does not affect the local structure of the graphene-like material. Also, when the structure of the graphene-like material obtained in this example was analyzed using means such as Raman spectrum, transmission electron microscope, XPS, XRD, etc., the following was found. The result of the Raman spectrum was I D / I G [[ID=J14]] = 0.483, I V / I G = 0.392. As is clear from the result of the transmission electron microscope, the graphene-like material produced in this example has a uniform shape and size distribution, and the diameter is 3.86 ± 0.05 nm. As is clear from the result of XPS, the sp 2 hybridization mode of carbon atoms accounts for about 85.93%.

[0048] Example 3 In this example, a graphene analog was produced using metallurgical coke powder from a steel mill. The specific procedure was as follows.

[0049] 1. Crushing and sieving: Metallurgical coke powder was ball-milled using a high-energy planetary ball mill. The ball milling time was 8 hours, and the ball milling speed was set to an orbital speed of 50 r / min and a rotational speed of 300 r / min. After sieving, ultrafine coke powder with a particle size of 1 μm or less was obtained.

[0050] 2. High-pressure extraction: A mixed solvent of tetrahydrofuran (THF) and N-methylpyrrolidone was used as the extractant. The ultrafine coke powder and the extractant were placed in a high-pressure reactor in a solid-liquid ratio of 1:50 and heated to a target temperature of 350°C under a high-purity Ar atmosphere, then kept at a constant temperature for 3 hours. During the heating process, the pressure was maintained at 2.0 MPa and the stirring speed was 600 r / min. After natural cooling to room temperature, the mixture was removed and solid-liquid separation was performed using a centrifuge. The solvent was removed from the separated liquid phase by rotary evaporation, and the solvent was recycled. The solid obtained by rotary evaporation was repeatedly washed with deionized water, and then vacuum-dried in a vacuum oven at 60°C for 16 hours to obtain ultra-high-purity carbon.

[0051] 3. Chemical oxidation: Ultra-high purity carbon, sodium nitrate (NaNO3), and potassium permanganate (KMNO4) were placed in a 1:1:7 ratio in a 500 ml reaction bottle and mixed in an ice bath. The reaction was carried out for 20 minutes with stirring while controlling the reaction temperature to 15°C. Then the temperature was raised to 30°C and stirred for another 40 minutes. Next, deionized water was gradually added in a 1:1 volume ratio. After 20 minutes, hydrogen peroxide was added to reduce the remaining oxidizing agent, turning the solution a bright yellow. The solution was filtered while still hot, and the filtrate was repeatedly washed with a 5% HCl solution and deionized water until no sulfate groups were detected in the filtrate. Finally, the filtered cake was thoroughly dried in a vacuum oven at 70°C to obtain the carbon oxide material.

[0052] 4. Solid-phase reduction: The obtained carbon oxide material was activated at 1200°C for 2 hours in a furnace with a high-temperature atmosphere filled with protective gas to obtain an activated graphene analog precursor material. 5. Solvent exfoliation: The graphene analog precursor material was dispersed in a 1 mg / mL N-methylpyrrolidone (NMP) solution, sonicated at 70°C for 6 hours, and then the resulting solution was rotated and evaporated to finally obtain the graphene analog.

[0053] The graphene analog obtained in this embodiment has an extremely low impurity content (less than 0.03%) and does not affect the local structure of the graphene analog material. Furthermore, when the structure of the graphene analog obtained in this embodiment was analyzed using methods such as Raman spectroscopy, transmission electron microscopy, XPS, and XRD, the following was found. The Raman spectroscopy results were as follows: D / I G =0.475, I V / I G = 0.373. As is clear from the transmission electron microscope results, the graphene analog material produced by this embodiment had a uniform shape and size distribution, with a diameter of 4.23 ± 0.05 nm. As is clear from the XPS results, the sp of carbon atoms was 2 Hybrid methods account for approximately 87.48%.

[0054] The foregoing are merely preferred embodiments of the present invention and do not limit the scope of protection of the present invention. Equivalent substitutions and modifications made by those skilled in the art within the technical scope disclosed herein, based on the technical means and the spirit of the invention, are all within the scope of protection of the present invention.

Claims

1. A method for producing a graphene analog using metallurgical coke powder, characterized by including the following steps. 1) A crushing and sieving process in which metallurgical coke powder is polished and sieved to obtain ultrafine coke powder with a particle size of 20 μm or less, 2) A high-pressure extraction process in which ultrafine coke powder and an extractant are placed in a high-pressure reactor, and high-pressure extraction is performed under protective atmosphere at a constant temperature of 0.4 to 5.0 MPa and 200 to 400°C for 1 to 6 hours, followed by centrifugation, rotary evaporation, and drying to obtain ultra-high-purity carbon. 3) A chemical oxidation process to obtain an oxide carbon material by reacting ultra-high purity carbon with sodium nitrate and potassium permanganate, which are strong oxidizing agents, 4) A solid-phase reduction step in which a carbon oxide material is reduced at a temperature of 1000°C to 1200°C under a protective atmosphere to obtain an activated graphene analog precursor material, 5) A solvent exfoliation step in which a graphene analog precursor material is exfoliated in an organic solvent to obtain a graphene analog.

2. The method for producing a graphene analog using metallurgical coke powder according to claim 1, characterized in that, in step 1), the particle size of the metallurgical coke powder is less than 5 mm, polishing is performed using a high-energy planetary ball mill, the ball milling time is 6 to 12 hours, the ball milling speed is 50 to 200 r / min for the orbital speed and 200 to 400 r / min for the rotational speed, the material of the ball mill tank is stainless steel, and the material of the milling balls is zirconia.

3. The method for producing a graphene analog using metallurgical coke powder according to claim 1, characterized in that, in step 2), the solid-liquid ratio of ultrafine coke powder to extractant is 1:20 to 1:50, and the extractant is one of the following. (1) N-methylpyrrolidone as a single solvent, (2) A mixed solvent of n-hexane and N-methylpyrrolidone in a volume ratio of 1:1 to 5:1, (3) A mixed solvent of tetrahydrofuran and N-methylpyrrolidone in a volume ratio of 1:1 to 5:

1.

4. In step 2), the mixture of ultrafine coke powder and extractant is stirred at a stirring speed of 200 to 600 r / min during the extraction process; the protective atmosphere is high-purity N ２ A method for producing a graphene analog using metallurgical coke powder according to claim 1, characterized in that it is high-purity Ar.

5. The method for producing a graphene analog using metallurgical coke powder according to claim 1, characterized in that step 2) involves centrifugation, rotary evaporation, and drying, which involves separating the solid and liquid phases by centrifugation, removing the solvent from the separated liquid phase by rotary evaporation, washing the solid obtained by rotary evaporation, and then drying it in a vacuum oven at a temperature of 55 to 75°C for 12 to 24 hours.

6. The method for producing a graphene analog using metallurgical coke powder according to claim 1, characterized in that, in step 3), the mixing ratio of ultra-high purity carbon and strong oxidizing agent is 1:1:5 to 1:1:9 for ultra-high purity carbon:sodium nitrate:potassium permanganate.

7. The method for producing a graphene analog using metallurgical coke powder according to claim 1, characterized in that the operation process of step 3) involves mixing ultra-high purity carbon and a strong oxidizing agent in an ice bath, reacting for 10 to 30 minutes under stirring while controlling the reaction temperature to 20°C or below, then raising the temperature to 30 to 40°C and stirring for a further 25 to 60 minutes; then gradually adding deionized water in a 1:1 volume ratio, and after 15 to 25 minutes adding hydrogen peroxide to reduce the remaining oxidizing agent and change the solution to a bright yellow color; filtering while hot, washing with a 5% HCl solution and deionized water until sulfate groups are no longer detectable from the filtrate; and finally drying the filtered cake in a vacuum oven at 50 to 80°C to obtain an oxide carbon material.

8. In step 4), the solid-phase reduction reaction time is 1 to 3 hours, and the protective atmosphere is high-purity N ２ A method for producing a graphene analog using metallurgical coke powder according to claim 1, characterized in that it is high-purity Ar.

9. The method for producing a graphene analog using metallurgical coke powder according to claim 1, characterized in that step 5) involves, specifically, dispersing a graphene analog precursor material in an N-methylpyrrolidone solution with a concentration of 1 mg / mL, sonicating it at a temperature of 50 to 70°C for 3 to 6 hours, and then rotating and evaporating the resulting solution to finally obtain a graphene analog.

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