Coal-based graphitized carbon utilizing heterogeneous nucleation path in liquid-phase carbonization process and preparation method of coal-based graphitized carbon

Abstract

The invention belongs to the technical field of carbon material processing, and discloses coal-based graphitized carbon utilizing a heterogeneous nucleation path in a liquid-phase carbonization process and a preparation method of the coal-based graphitized carbon. Uniformly mixing the pretreated pulverized coal, carbonaceous seed crystal and inert molten salt to obtain a solid-phase mixture; pyrolyzing the solid-phase mixture for 2-4 hours at 800-1000 DEG C in an inert atmosphere, and then cooling to obtain a reaction product; washing the reaction product to remove the inert molten salt; and then carrying out deashing treatment and washing to obtain the coal-based graphitized carbon utilizing the heterogeneous nucleation path in the liquid-phase carbonization process. According to the method, a carbonaceous additive with a mature graphite microcrystalline structure is added in solid-phase pyrolysis of coal as a heterogeneous nucleation site and molten salt is added as a liquid-phase reaction medium, so that ordered arrangement and growth of carbon fragments near a crystal nucleus are induced while activation energy is reduced, and development of a coal-based crystalline carbon structure is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon material processing, and particularly relates to coal-based graphitized carbon utilizing a heterogeneous nucleation path during the liquid-phase carbonization process and a preparation method thereof. Background Art

[0002] The graphitization degree is a key characteristic index in carbonaceous materials. A high graphitization degree means excellent electronic conductivity, low internal resistance, and good chemical stability. Currently, there are two main ways to improve the graphitization degree of carbon materials: one is through high-temperature heat treatment, and the other is to introduce transition metal ion-based catalysts to promote the rearrangement of carbon atoms [Catalytic graphitization in anthracite by reduced iron particles and investigating the mechanism of catalytic transformation via molecular dynamics[J].Carbon,2022,188:336 - 348]. However, the former requires harsh experimental conditions and extremely high energy consumption (>2500 °C) [Graphene sheets from graphitized anthracite coal: preparation, decoration, and application[J].Energy & fuels,2012,26(8):5186 - 5192], and the latter will generate metal oxide / metal nanoparticle impurities that are difficult to remove during the thermal transformation process [Patent: CN 102867654 A]. As is well known, coal-derived derivatives such as tar and asphalt are prone to form long-range graphite structures after liquid-phase carbonization and have the ability to develop crystalline carbon structures at low temperatures (~400–600 °C), which is closely related to the nucleation behavior and evolution path of the carbonaceous mesophase. Nevertheless, due to the low mobility of carbon atoms and the lack of the ability of homogeneous nucleation, this process is difficult to effectively proceed in the solid-phase pyrolysis behavior of coal, so the carbon product exhibits an amorphous non-crystalline characteristic. Summary of the Invention

[0003] To solve the problems existing in the prior art, the purpose of the present invention is to provide coal-based graphitized carbon utilizing a heterogeneous nucleation path during the liquid-phase carbonization process and a preparation method thereof. The present invention adds a carbonaceous additive with a mature graphite microcrystalline structure as a heterogeneous nucleation site and a molten salt as a liquid-phase reaction medium during the solid-phase pyrolysis of coal, inducing the ordered arrangement and growth of carbon fragments near the crystal nuclei while reducing the activation energy, and realizing the development of a coal-based crystalline carbon structure.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A preparation method of coal-based graphitized carbon using a heterogeneous nucleation path in the liquid-phase carbonization process, comprising the following steps:

[0006] Oxidatively depolymerize pulverized coal to obtain pretreated pulverized coal;

[0007] Mix the pretreated pulverized coal, carbonaceous seeds, and inert molten salt to obtain a solid-phase mixture;

[0008] Pyrolyze the solid-phase mixture in an inert atmosphere at 800 - 1000 °C for 2 - 4 h, and then cool to obtain a reaction product;

[0009] Wash the reaction product to remove the inert molten salt; then perform deashing treatment and washing to obtain the coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process.

[0010] Preferably, the pulverized coal is bituminous coal.

[0011] Preferably, the particle size of the pulverized coal is above 80 mesh.

[0012] Preferably, the process of oxidatively depolymerizing pulverized coal to obtain pretreated pulverized coal includes:

[0013] Oxidatively depolymerize the pretreated pulverized coal in a concentrated acid solution under ice-bath conditions for 10 - 14 h, then perform solid-liquid separation, wash to neutrality, and dry to obtain the pretreated pulverized coal.

[0014] Preferably, the concentrated acid is an acid mixture composed of concentrated sulfuric acid and concentrated nitric acid in a mass ratio of 1:(2.5 - 3.5);

[0015] Preferably, the carbonaceous seeds are at least one of graphene oxide, graphite powder, and carbon black.

[0016] Preferably, the inert molten salt is a LiCl-KCl molten salt system, wherein the molar ratio of LiCl to KCl is 4.5:5.5.

[0017] Preferably, in the solid-phase mixture, the mass of the carbonaceous seeds is 10% - 20% of the mass of the pretreated pulverized coal, and the total mass of the pretreated pulverized coal and the carbonaceous seeds is 5% - 20% of the mass of the inert molten salt.

[0018] Preferably, the process of washing the reaction product to remove the inert molten salt; then performing deashing treatment and washing to obtain the coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process includes:

[0019] The product after the reaction is washed with deionized water to dissolve the inert molten salt; then pickling and water washing treatments are carried out to deash the product after the reaction; then the reaction product is washed to neutrality and dried to remove moisture, and the coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process is obtained.

[0020] The present invention also provides a coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process prepared by the preparation method as described above.

[0021] The present invention has the following beneficial effects:

[0022] In the preparation method of the present invention, by utilizing the idea that the liquid-phase carbonization path is easy to develop graphitization, exogenous seeds are introduced as heterogeneous nucleation sites in the traditional solid-phase pyrolysis of coal, solving the shortcoming that it is difficult to effectively carry out nucleation behavior in the solid-phase carbonization process. The present invention selectively extracts and utilizes the macromolecular structure of coal through an acidolysis pretreatment method. The depolymerized carbon fragments are more likely to be arranged near the crystal nuclei, so as to achieve a deeper regulation intensity. In the present invention, an inert molten salt is used as the liquid-phase reaction medium. On the one hand, the presence of the molten salt can provide a closed environment, promoting the cross-linking of free radical fragments generated in the initial stage of pyrolysis with the crystal nuclei, which is beneficial to the development of the crystalline carbon structure; on the other hand, the molten salt existing in a flowing form can increase the carbon atom mobility, promoting the transformation from "non-mesophase" to "mesophase", enabling more cracking fragments to participate in nucleation and subsequent graphitization. In addition, the experimental conditions of the present invention are relatively mild, and the selected molten salt does not have strong corrosiveness, reducing the equipment usage requirements; in addition, the used salt can be recycled for secondary use, having indirect economic and environmental benefits. Description of the Drawings

[0023] Figure 1 It is a comparative diagram of the microcrystalline structures of the pyrolysis products of Example 1, Example 2 and Comparative Example 1 of the present invention. Detailed Embodiments

[0024] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0025] The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process of the present invention includes the following steps:

[0026] Step 1: Using bituminous coal (which has high-viscosity components) as the carbon source, after crushing and screening, take the undersize material to obtain refined coal powder with a particle size of more than 80 mesh.

[0027] Step 2: Place the coal powder obtained in Step 1 in a concentrated acid solution for oxidative depolymerization. Among them, the concentrated acid solution is an acid prepared by mixing concentrated sulfuric acid and concentrated nitric acid in a mass ratio of 1:(2.5 - 3.5). The oxidative depolymerization process is carried out under ice-bath conditions, and the treatment time is 10 - 14 h. After the oxidative depolymerization is completed, perform solid-liquid separation, wash until neutral, and dry to obtain pretreated coal powder.

[0028] Step 3: Add carbonaceous seeds to the pretreated coal powder obtained in Step 2, and then add LiCl-KCl inert molten salt. After mixing, a solid-phase mixture is obtained; among them, the carbonaceous seeds are at least one of graphene oxide, graphite powder, and carbon black; the mass of the carbonaceous seeds is 10% - 20% of the mass of the pretreated coal powder, and the total mass of the pretreated coal powder and the carbonaceous seeds is 5% - 20% of the mass of the inert molten salt; in the LiCl-KCl inert molten salt, the molar ratio of LiCl to KCl is 4.5:5.5. Then transfer the solid-phase mixture to a nickel crucible and place it in a tubular furnace. Set the reaction temperature to 800 - 1000 °C, and carry out pyrolysis for 2 - 4 h under an inert atmosphere. After the heat preservation is completed, cool to room temperature to obtain a reaction product.

[0029] Step 4: Take out the reaction product obtained in Step 3 and place it in deionized water for water washing treatment. Wash repeatedly to fully dissolve the LiCl-KCl inert molten salt, and then recover the washing solution.

[0030] Step 5: Perform acid washing and water washing treatment on the reaction product after water washing in Step 4 for deep ash removal. After the pH becomes neutral, carry out suction filtration and drying to obtain coal-based graphitized carbon.

[0031] In the following examples of the present invention, the mass fraction of concentrated sulfuric acid is 98%, and the mass fraction of concentrated nitric acid is 68%.

[0032] Example 1

[0033] The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process of this example includes the following steps:

[0034] Step 1: Using bituminous coal as the carbon source, after crushing and screening, take the undersize material to obtain refined coal powder with a particle size of more than 80 mesh.

[0035] Step 2: Place the pulverized coal obtained in Step 1 into a concentrated acid solution for oxidative depolymerization. The concentrated acid solution is an acid mixture composed of concentrated sulfuric acid and concentrated nitric acid in a mass ratio of 1:3. The oxidative depolymerization process is carried out under ice bath conditions for 12 hours. After the oxidative depolymerization is completed, solid-liquid separation, washing until neutral, and drying are performed to obtain pretreated pulverized coal.

[0036] Step 3: Add carbonaceous seeds to the pretreated pulverized coal obtained in Step 2, and then add LiCl-KCl inert molten salt. After mixing, a solid-phase mixture is obtained. Among them, the carbonaceous seeds are graphene oxide; the mass of the carbonaceous seeds is 10% of the mass of the pretreated pulverized coal, and the total mass of the pretreated pulverized coal and the carbonaceous seeds is 10% of the mass of the inert molten salt; in the LiCl-KCl inert molten salt, the molar ratio of LiCl to KCl is 4.5:5.5. Then transfer the solid-phase mixture to a nickel crucible and place it in a tube furnace. Set the reaction temperature to 900 °C and carry out pyrolysis for 3 hours under an inert atmosphere. After the heat preservation is completed, cool it to room temperature to obtain the reaction product.

[0037] Step 4: Take out the reaction product obtained in Step 3 and place it in deionized water for washing treatment. Wash repeatedly to fully dissolve the LiCl-KCl inert molten salt, and then recover the washing solution.

[0038] Step 5: Perform acid washing and water washing treatment on the reaction product after water washing in Step 4 for deep ash removal. Until the pH is neutral, carry out suction filtration and drying to obtain coal-based graphitized carbon.

[0039] As Figure 1 shown, it can be seen that the coal-based graphitized carbon obtained in this example has a graphitized structure.

[0040] After testing, the specific surface area of the coal-based graphitized carbon obtained in this example is 906 m 2 g -1 .

[0041] Example 2

[0042] The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process in this example includes the following steps:

[0043] Step 1: Use bituminous coal as the carbon source, break and screen it, and take the undersize material to obtain refined pulverized coal with a particle size of more than 80 mesh.

[0044] Step 2: Place the pulverized coal obtained in Step 1 into a concentrated acid solution for oxidative depolymerization. The concentrated acid solution is an acid mixture composed of concentrated sulfuric acid and concentrated nitric acid in a mass ratio of 1:3. The oxidative depolymerization process is carried out under ice bath conditions for 12 hours. After the oxidative depolymerization is completed, solid-liquid separation, washing until neutral, and drying are performed to obtain pretreated pulverized coal.

[0045] Step 3: Add carbonaceous seeds to the pretreated pulverized coal obtained in Step 2, and then add LiCl-KCl inert molten salt. After mixing, a solid-phase mixture is obtained. Among them, the carbonaceous seeds are graphene oxide. The mass of the carbonaceous seeds is 20% of the mass of the pretreated pulverized coal, and the total mass of the pretreated pulverized coal and the carbonaceous seeds is 10% of the mass of the inert molten salt. In the LiCl-KCl inert molten salt, the molar ratio of LiCl to KCl is 4.5:5.5. Then transfer the solid-phase mixture to a nickel crucible and place it in a tubular furnace. Set the reaction temperature to 900 °C and carry out pyrolysis for 3 h under an inert atmosphere. After the heat preservation is completed, cool it to room temperature to obtain the reaction product.

[0046] Step 4: Take out the reaction product obtained in Step 3 and place it in deionized water for washing. Wash repeatedly to fully dissolve the LiCl-KCl inert molten salt, and then recover the washing solution.

[0047] Step 5: Subject the reaction product washed in Step 4 to acid washing and then water washing again for deep ash removal. After the pH becomes neutral, carry out suction filtration and drying to obtain coal-based graphitized carbon.

[0048] As Figure 1 shown, it can be seen that the coal-based graphitized carbon obtained in this example has a graphitized structure.

[0049] After testing, the specific surface area of the coal-based graphitized carbon obtained in this example is 608 m 2 g -1 .

[0050] Comparative Example 1

[0051] The preparation method of this comparative example includes the following steps:

[0052] Step 1: Use bituminous coal as the carbon source. After crushing and screening, take the undersize material to obtain refined pulverized coal with a particle size of more than 80 mesh.

[0053] Step 2: Place the pulverized coal obtained in Step 1 in a concentrated acid solution for oxidative depolymerization. Among them, the concentrated acid solution is an acid mixture composed of concentrated sulfuric acid and concentrated nitric acid in a mass ratio of 1:3. The oxidative depolymerization process is carried out under ice bath conditions for 12 h. After the oxidative depolymerization is completed, carry out solid-liquid separation, wash until neutral, and dry to obtain pretreated pulverized coal.

[0054] Step 3: Add LiCl-KCl inert molten salt to the pretreated pulverized coal obtained in Step 2, and mix to obtain a solid-phase mixture; among them, the mass of the pretreated pulverized coal is 10% of the mass of the inert molten salt; in the LiCl-KCl inert molten salt, the molar ratio of LiCl to KCl is 4.5:5.5. Then transfer the solid-phase mixture to a nickel crucible and place it in a tubular furnace, set the reaction temperature to 900 °C, carry out pyrolysis for 3 h under an inert atmosphere, and cool to room temperature after the heat preservation is completed to obtain a reaction product.

[0055] Step 4: Take out the reaction product obtained in Step 3 and place it in deionized water for washing treatment, wash repeatedly to fully dissolve the LiCl-KCl inert molten salt, and then recover the washing solution.

[0056] Step 5: Carry out acid washing and water washing treatment on the reaction product washed in Step 4 to deeply remove ash. After the pH is neutral, carry out suction filtration and drying to obtain a pyrolysis product.

[0057] As Figure 1 shown, it can be seen that the pyrolysis product obtained in this comparative example shows an amorphous characteristic and has no graphitized structure.

[0058] After testing, the specific surface area of the pyrolysis product obtained in this comparative example is ~700 m 2 g -1 .

[0059] In summary, according to Figure 1 it can be known that the carbon (DC) formed by directly pyrolyzing coal in Comparative Example 1 shows an amorphous characteristic. With the introduction of graphene oxide nucleating agent (such as Example 1 and Example 2), the graphitization degree of the obtained GDC is significantly improved.

[0060] Example 3

[0061] The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process in this example includes the following steps:

[0062] Step 1: Use bituminous coal as a carbon source, crush and screen it, take the undersize material to obtain refined pulverized coal with a particle size of more than 80 mesh.

[0063] Step 2: Place the pulverized coal obtained in Step 1 in a concentrated acid solution for oxidative depolymerization. Among them, the concentrated acid solution is an acid mixture of concentrated sulfuric acid and concentrated nitric acid in a mass ratio of 1:2.5. The oxidative depolymerization process is carried out under ice bath conditions, and the treatment time is 14 h. After the oxidative depolymerization is completed, carry out solid-liquid separation, wash to neutrality, and dry to obtain pretreated pulverized coal.

[0064] Step 3: Add carbonaceous seeds to the pretreated pulverized coal obtained in Step 2, and then add LiCl-KCl inert molten salt. After mixing, a solid-phase mixture is obtained. Among them, the carbonaceous seeds are graphite powder. The mass of the carbonaceous seeds is 15% of the mass of the pretreated pulverized coal, and the total mass of the pretreated pulverized coal and the carbonaceous seeds is 12% of the mass of the inert molten salt. In the LiCl-KCl inert molten salt, the molar ratio of LiCl to KCl is 4.5:5.5. Then transfer the solid-phase mixture to a nickel crucible and place it in a tubular furnace. Set the reaction temperature to 1000 °C and carry out pyrolysis for 2 h under an inert atmosphere. After the heat preservation is completed, cool it to room temperature to obtain the reaction product.

[0065] Step 4: Take out the reaction product obtained in Step 3 and place it in deionized water for washing. Wash repeatedly to fully dissolve the LiCl-KCl inert molten salt, and then recover the washing liquid.

[0066] Step 5: Perform acid washing and water washing on the reaction product after water washing in Step 4 for deep ash removal. After the pH becomes neutral, carry out suction filtration and drying to obtain coal-based graphitized carbon.

[0067] After testing, the specific surface area of the coal-based graphitized carbon obtained in this example is 795 m 2 g -1 .

[0068] Example 4

[0069] The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process in this example includes the following steps:

[0070] Step 1: Use bituminous coal as the carbon source. After crushing and screening, take the undersize material to obtain refined pulverized coal with a particle size of more than 80 mesh.

[0071] Step 2: Place the pulverized coal obtained in Step 1 in a concentrated acid solution for oxidative depolymerization. Among them, the concentrated acid solution is an acid mixture of concentrated sulfuric acid and concentrated nitric acid in a mass ratio of 1:3.5. The oxidative depolymerization process is carried out under ice bath conditions for 10 h. After the oxidative depolymerization is completed, carry out solid-liquid separation, wash until neutral, and dry to obtain pretreated pulverized coal.

[0072] Step 3: Add carbonaceous seeds to the pretreated pulverized coal obtained in Step 2, and then add LiCl-KCl inert molten salt. After mixing, a solid-phase mixture is obtained. Among them, the carbonaceous seeds are carbon black. The mass of the carbonaceous seeds is 18% of the mass of the pretreated pulverized coal, and the total mass of the pretreated pulverized coal and the carbonaceous seeds is 8% of the mass of the inert molten salt. In the LiCl-KCl inert molten salt, the molar ratio of LiCl to KCl is 4.5:5.5. Then transfer the solid-phase mixture to a nickel crucible and place it in a tubular furnace. Set the reaction temperature to 800 °C and carry out pyrolysis for 4 h under an inert atmosphere. After the heat preservation is completed, cool it to room temperature to obtain the reaction product.

[0073] Step 4: Take out the reaction product obtained in Step 3 and place it in deionized water for washing. Wash repeatedly to fully dissolve the LiCl-KCl inert molten salt, and then recover the washing solution.

[0074] Step 5: Perform acid washing and water washing on the reaction product after water washing in Step 4 for deep ash removal. After the pH becomes neutral, perform suction filtration and drying to obtain coal-based graphitized carbon.

[0075] After testing, the specific surface area of the coal-based graphitized carbon obtained in this example is 867 m 2 g -1 .

[0076] Example 5

[0077] The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process in this example includes the following steps:

[0078] Step 1: Use bituminous coal as the carbon source. After crushing and screening, take the undersize material to obtain refined coal powder with a particle size of more than 80 mesh.

[0079] Step 2: Place the coal powder obtained in Step 1 in a concentrated acid solution for oxidative depolymerization. Among them, the concentrated acid solution is an acid formed by mixing concentrated sulfuric acid and concentrated nitric acid in a mass ratio of 1:3. The oxidative depolymerization process is carried out under ice bath conditions for 12 h. After the oxidative depolymerization is completed, perform solid-liquid separation, wash until neutral, and dry to obtain pretreated coal powder.

[0080] Step 3: Add carbonaceous seeds to the pretreated coal powder obtained in Step 2, and then add LiCl-KCl inert molten salt. After mixing, obtain a solid-phase mixture; among them, the carbonaceous seeds are a mixture formed by mixing graphene oxide, graphite powder, and carbon black in an equal mass ratio; the mass of the carbonaceous seeds is 20% of the mass of the pretreated coal powder, and the total mass of the pretreated coal powder and the carbonaceous seeds is 5% of the mass of the inert molten salt; in the LiCl-KCl inert molten salt, the molar ratio of LiCl to KCl is 4.5:5.5. Then transfer the solid-phase mixture to a nickel crucible and place it in a tube furnace. Set the reaction temperature to 1000 °C and carry out pyrolysis for 4 h under an inert atmosphere. After the heat preservation is completed, cool to room temperature to obtain a reaction product.

[0081] Step 4: Take out the reaction product obtained in Step 3 and place it in deionized water for washing. Wash repeatedly to fully dissolve the LiCl-KCl inert molten salt, and then recover the washing solution.

[0082] Step 5: Perform acid washing and water washing on the reaction product after water washing in Step 4 for deep ash removal. After the pH becomes neutral, perform suction filtration and drying to obtain coal-based graphitized carbon.

[0083] After testing, the specific surface area of the coal-based graphitized carbon obtained in this example is 690 m 2 g -1 .

[0084] Example 6

[0085] The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process in this example includes the following steps:

[0086] Step 1: Using bituminous coal as the carbon source, after crushing and screening, take the undersize material to obtain refined coal powder with a particle size of more than 80 mesh.

[0087] Step 2: Place the coal powder obtained in Step 1 in a concentrated acid solution for oxidative depolymerization. Among them, the concentrated acid solution is an acid prepared by mixing concentrated sulfuric acid and concentrated nitric acid in a mass ratio of 1:3. The oxidative depolymerization process is carried out under ice bath conditions, and the treatment time is 14 h. After the oxidative depolymerization is completed, perform solid-liquid separation, wash until neutral, and dry to obtain pretreated coal powder.

[0088] Step 3: Add carbonaceous seeds to the pretreated coal powder obtained in Step 2, and then add LiCl-KCl inert molten salt. After mixing, a solid-phase mixture is obtained; among them, the carbonaceous seeds are a mixture prepared by mixing graphene oxide and graphite powder in an equal mass ratio; the mass of the carbonaceous seeds is 15% of the mass of the pretreated coal powder, and the total mass of the pretreated coal powder and the carbonaceous seeds is 20% of the mass of the inert molten salt; in the LiCl-KCl inert molten salt, the molar ratio of LiCl to KCl is 4.5:5.5. Then transfer the solid-phase mixture to a nickel crucible and place it in a tubular furnace. Set the reaction temperature to 950 °C and carry out pyrolysis for 3.5 h under an inert atmosphere. After the heat preservation is completed, cool to room temperature to obtain the reaction product.

[0089] Step 4: Take out the reaction product obtained in Step 3 and place it in deionized water for water washing treatment. Wash repeatedly to fully dissolve the LiCl-KCl inert molten salt, and then recover the washing solution.

[0090] Step 5: Perform acid washing and water washing treatment on the reaction product after water washing in Step 4 for deep ash removal. Until the pH is neutral, perform suction filtration and drying to obtain coal-based graphitized carbon.

[0091] After testing, the specific surface area of the coal-based graphitized carbon obtained in this example is 735 m 2 g -1 .

[0092] As can be seen from the above results, the above solution of the present invention utilizes the idea of developing graphitization through the liquid-phase carbonization path, adding a carbonaceous additive with a mature graphite microcrystalline structure as a heterogeneous nucleation site and molten salt as a liquid-phase reaction medium during the solid-phase pyrolysis of coal. While reducing the activation energy, it induces the ordered arrangement and growth of carbon fragments near the crystal nuclei, realizing the development of a coal-based crystalline carbon structure. The present invention does not require experimental conditions of ultra-high temperature and high pressure and the use of strongly corrosive reagents. The reaction process is simple and mild, and the obtained carbon materials are applicable to a wide range of energy storage fields.

[0093] Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent substitutions can still be made to the specific embodiments of the present invention. Any modification or equivalent substitution without departing from the spirit and scope of the present invention shall be covered by the scope of the present invention.

Claims

1. A preparation method of coal-based graphitized carbon using a heterogeneous nucleation path in a liquid-phase carbonization process, characterized in that, It includes the following processes: Oxidatively depolymerize pulverized coal to obtain pretreated pulverized coal; Mix the pretreated pulverized coal, carbonaceous crystal seeds and inert molten salt to obtain a solid-phase mixture; Pyrolyze the solid-phase mixture in an inert atmosphere at 800 - 1000 °C for 2 - 4 h, and then cool to obtain a reaction product; Wash the reaction product to remove the inert molten salt; Then perform deashing treatment and washing to obtain the coal-based graphitized carbon using the heterogeneous nucleation path of the liquid-phase carbonization process.

2. The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process according to claim 1, characterized in that, The pulverized coal used is bituminous coal.

3. The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process according to claim 1, characterized in that, The particle size of the pulverized coal is above 80 mesh.

4. The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process according to claim 1, characterized in that, The process of oxidatively depolymerizing pulverized coal to obtain pretreated pulverized coal includes: Oxidatively depolymerize the pretreated pulverized coal in a concentrated acid solution under ice bath conditions for 10 - 14 h, then perform solid-liquid separation, wash until neutral, and dry to obtain the pretreated pulverized coal.

5. The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process according to claim 4, characterized in that, The concentrated acid is an acid prepared by mixing concentrated sulfuric acid and concentrated nitric acid in a mass ratio of 1:(2.5 - 3.5).

6. The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path of the liquid-phase carbonization process according to claim 1, characterized in that, The carbonaceous crystal seeds are at least one of graphene oxide, graphite powder and carbon black.

7. The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process according to claim 1, characterized in that, The inert molten salt uses a LiCl-KCl molten salt system, where the molar ratio of LiCl to KCl is 4.5:5.

5.

8. A method for preparing coal-based graphitized carbon using a heterogeneous nucleation path in a liquid-phase carbonization process according to claim 1, characterized in that, In the solid-phase mixture, the mass of the carbonaceous crystal seeds is 10% - 20% of the mass of the pretreated pulverized coal, and the total mass of the pretreated pulverized coal and the carbonaceous crystal seeds is 5% - 20% of the mass of the inert molten salt.

9. The preparation method of coal-based graphitized carbon using the heterogeneous nucleation path in the liquid-phase carbonization process according to claim 1, characterized in that, Wash the reaction product to remove the inert molten salt; Then perform deashing treatment and washing to obtain the coal-based graphitized carbon using the heterogeneous nucleation path of the liquid-phase carbonization process, including: Wash the post-reaction product with deionized water to dissolve the inert molten salt; then perform acid washing and water washing treatment to deash the post-reaction product; then wash the reaction product until neutral and dry to remove moisture to obtain the coal-based graphitized carbon using the heterogeneous nucleation path of the liquid-phase carbonization process.

10. The coal-based graphitized carbon using the heterogeneous nucleation path of the liquid-phase carbonization process prepared by the preparation method according to any one of claims 1 - 9.

Images