A structured designable carbonaceous material precursor, and a method of making and using the same

Abstract

This invention relates to the field of functional materials preparation, specifically disclosing a structurally designable carbonaceous material precursor, its preparation method, and its applications. The preparation method includes the following steps: determining the reaction medium and reaction temperature T based on the desired structure of the carbonaceous material; the reaction medium is a molten salt system formed by a metal halide and its water of crystallization; adding an initial carbon source, cellulose and / or hemicellulose, to the reaction medium; catalyzing the initial carbon source reaction at the reaction temperature T for 0.5-5 hours; and then performing solid-liquid separation to obtain a solid-phase carbonaceous material precursor. The reaction temperature T is 100-220℃. This method allows for structural control during the precursor preparation stage, ensuring that the final carbonaceous material's microstructure, pore structure, etc., meet the target application requirements and satisfy the requirements for high-end carbon materials.

Description

Technical Field

[0001] This invention relates to the field of functional materials preparation, and specifically discloses a structurally designable carbonaceous material precursor, its preparation method, and its application. Background Technology

[0002] Carbonaceous materials, due to their excellent chemical stability, are widely used in energy storage, catalyst supports, adsorption separation, and electrochemical devices. The structure and composition of carbonaceous material precursors directly determine the microstructure, pore structure, graphitization degree, and application performance of the final carbon material. Therefore, developing structurally designable, mild, green, and low-cost methods for preparing carbonaceous material precursors is an important research direction in this field.

[0003] Currently, the main methods for preparing carbonaceous material precursors include direct high-temperature carbonization, chemical activation, template methods, hydrothermal / solvothermal methods, and molten salt-assisted pyrolysis. Existing technologies generally suffer from the following technical bottlenecks: High reaction temperature and high energy consumption: Conventional carbonization and activation processes are mostly carried out at temperatures above 400℃ or even as high as 800–1200℃. High temperatures can easily lead to excessive shrinkage of the carbon skeleton, collapse of the pore structure, and loss of a large number of surface active functional groups, making it difficult to retain a controllable structure.

[0004] Poor structural controllability: Traditional methods rely heavily on post-processing to control the structure, making it difficult to achieve the desired structural orientation design in the precursor stage. The uniformity and repeatability of the products are difficult to meet the requirements of high-end applications.

[0005] In summary, existing technologies struggle to simultaneously meet the industrialization requirements of low-temperature and mild conditions, designable structures, environmental friendliness, inexpensive and readily available raw materials, and simple processes. Therefore, developing a low-temperature catalytic method for the directional preparation of carbonaceous material precursors according to target structures is of great significance for overcoming existing technological bottlenecks and promoting the low-cost, green preparation of high-performance carbon materials. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a structurally designable carbonaceous material precursor, its preparation method, and its application.

[0007] According to one aspect of the present invention, a method for preparing a structurally designable carbonaceous material precursor is provided, comprising the following steps: Based on the expected structure of the carbonaceous material, the reaction medium and reaction temperature T are determined. The reaction medium is a molten salt system formed by a metal halide and its water of crystallization. The added metal halide can be one or more types. An initial carbon source, wherein the initial carbon source is cellulose and / or hemicellulose, is added to the reaction medium. The initial carbon source is catalyzed by the reaction medium at a reaction temperature T for 0.5-5 hours. The reaction time can be selected as 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 hours depending on the actual needs. After the reaction is completed, solid-liquid separation is performed to obtain a solid carbonaceous material precursor. The reaction temperature T is 100-220°C, preferably 140-200°C. Depending on the specific product, the temperature can be selected as 100°C, 120°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C or 220°C. The carbonaceous material precursor is a humin or a humin-like precursor.

[0008] The beneficial effects of the method for preparing carbonaceous material precursors in this invention are as follows: 1. Guided by the desired carbonaceous material structure, the reaction medium and reaction temperature are specifically determined. Through the catalytic effect of the molten system formed by the metal halide and its water of crystallization, the structure can be controlled in the precursor preparation stage, ensuring that the microstructure and pore structure of the final carbonaceous material meet the target application requirements and satisfy the requirements for the use of high-end carbon materials.

[0009] 2. The reaction conditions are mild, energy consumption is low, and equipment requirements are minimal, reducing industrialization costs. This invention controls the reaction temperature in a low-temperature range of 100-220℃, which significantly reduces energy consumption compared to the high-temperature processes of 400℃ or even 800-1200℃ in existing technologies. It also avoids problems such as carbon skeleton shrinkage, pore structure collapse, and loss of surface-active functional groups caused by high temperatures.

[0010] 3. Cellulose and / or hemicellulose are selected as the initial carbon source. They are widely distributed and inexpensive. Compared with traditional carbon sources, this not only reduces the cost of raw materials, but also realizes the high-value utilization of biomass resources, taking into account both economic efficiency and environmental sustainability.

[0011] Furthermore, the structure of the carbonaceous material precursor includes the shape of the carbon skeleton and the degree of order of the carbon skeleton. The shape of the carbon skeleton includes porous sponge-like, aggregated, or aggregated particles embedded in a porous sponge-like matrix. The aggregated state includes irregular aggregated, spherical aggregated, or ellipsoidal aggregated.

[0012] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: The precursor can be adapted to the application requirements of different scenarios: the porous sponge-like structure provides abundant specific surface area and pore structure, making it suitable for fields with high requirements for pore structure, such as catalyst supports and adsorption separation; the aggregated structure (especially spherical and ellipsoidal aggregates) facilitates the subsequent processing and shaping of carbon materials; the composite structure of aggregated particles embedded in a porous sponge-like matrix can combine the advantages of pore structure with shaping performance, broadening the application range of the precursor; at the same time, the controllable adjustment of the orderliness of the carbon skeleton can further optimize the core properties of the final carbon material, such as conductivity and mechanical stability, significantly improving the adaptability and application value of the final carbon material.

[0013] Furthermore, based on the expected structure of the carbonaceous material, the reaction medium and reaction temperature T are determined, including: based on the expected structure of the carbonaceous material, the acidity / alkalinity, water activity, and reaction temperature T of the molten salt system are determined, and the cation and water of crystallization content of the reaction medium are determined based on the acidity / alkalinity and water activity of the molten salt system.

[0014] The beneficial effects of adopting the above-mentioned further technical solution are as follows: First, the pH, water activity, and reaction temperature T of the molten salt system are determined according to the expected structure. Then, the cation and water of crystallization content of the reaction medium are determined based on the pH and water activity of the molten salt system. This achieves the directional control of the precursor structure of carbonaceous materials. By first clarifying the parameters of the molten salt system (such as pH and water activity), and then reverse-matching the cation type and water of crystallization content of the reaction medium, a closed-loop control of "expected structure → clarified parameters → medium composition" is formed.

[0015] Furthermore, based on the expected structure of the carbonaceous material, the reaction medium and reaction temperature T are determined, including: for carbonaceous materials with high carbon skeleton order, an acidic reaction medium with high water activity is selected; for carbonaceous materials with low carbon skeleton order, a neutral and / or low water activity reaction medium is selected; for carbonaceous materials with aggregated carbon skeletons, the reaction temperature T is preferably in the range of 160-220°C. The metal halide added in each reaction can be one or more, as long as the pH and water activity of the reaction medium are met.

[0016] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: Directional controllability of carbon skeleton order is achieved: acidic and / or water-active reaction media can promote the orderly arrangement and cross-linking of carbon source molecules, thereby obtaining precursors with high carbon skeleton order, suitable for scenarios requiring high conductivity and mechanical strength (such as energy storage electrode materials); neutral and / or water-active reaction media can inhibit excessive orderly aggregation of carbon source molecules, obtaining precursors with low carbon skeleton order and richer pore structure, suitable for fields requiring high pore utilization such as catalyst supports and adsorption separation. This solves the shortcomings of existing technologies that cannot control carbon skeleton order on demand and are difficult to adapt to different high-end application scenarios. Furthermore, combined with the control of carbon skeleton shape, it enables comprehensive and precise design of precursor structures, improving the application adaptability of carbon materials.

[0017] Furthermore, the metal halide is selected from at least one of calcium chloride, calcium bromide, lithium chloride, lithium bromide, zinc chloride, zinc bromide, ferric chloride, cobalt chloride, aluminum chloride, tin chloride, ruthenium chloride, and nickel chloride.

[0018] Furthermore, the reaction medium is a metal halide·nH2O, where n ranges from 2 to 10. The water activity of the molten salt system is controlled by adjusting the water of crystallization content n, thereby affecting the degree of order of the carbon chain.

[0019] Furthermore, the initial carbon source has a mass of 1-15 wt% of the reaction medium.

[0020] Furthermore, after adding an initial carbon source to the reaction medium, a shaping carbon source is introduced, which is glucose, fructose, or furfural; preferably, the furfural is 5-hydroxymethylfurfural, which can guide the initial carbon source to form regular carbon microspheres, resulting in aggregated carbonaceous materials. Glucose and fructose, as monosaccharides, readily undergo intramolecular dehydration to generate 5-hydroxymethylfurfural under heating conditions. The 5-hydroxymethylfurfural converted from glucose and fructose, or the 5-hydroxymethylfurfural pre-added to the system, undergoes intramolecular and intermolecular aldol condensation, resulting in a carbon precursor structure dominated by an ordered arrangement of furan rings. Directional regulation of the polymerization pathway (intermolecular dehydration and cyclization): When using 5-hydroxymethylfurfural as a raw material, due to the presence of furan rings, the reaction pathway mainly tends towards rearrangement after ring opening or direct aldol condensation and Diels-Alder reaction. This directional polymerization mode avoids random carbon chain breakage and recombination, causing molecules to tend to form curvature in a two-dimensional plane, providing a structural basis for spherical formation. Meanwhile, the hydroxyl configurations of fructose and glucose, as well as the hydrogen bonding sites of 5-hydroxymethylfurfural, can form a dynamic supramolecular network in solution through hydrogen bonding. This network acts as a soft template, restricting the disordered extension of polymer chains, guiding them to undergo ordered coiling and stacking, and ultimately promoting the formation of a regular morphology.

[0021] Furthermore, a catalyst is added to the reaction medium. The catalyst is either a Brønsted acid or a Lewis acid. Adding a Brønsted acid catalyst (such as HCl) tends to catalyze the formation of highly disordered precursors; while adding a Lewis acid catalyst (such as AlCl3) is more conducive to the formation of structures with higher order. During the catalytic reaction, Lewis acids can promote the conversion of sugars to 5-hydroxymethylfurfural. Furthermore, the catalyst-mediated coordination makes the reaction relatively mild and the reaction rate slow. This facilitates molecular rearrangement during the formation of carbon precursors, thus increasing the order of the generated carbon precursors.

[0022] According to a second aspect of the present invention, a carbonaceous material precursor is provided, which is prepared by any of the preparation methods described above.

[0023] According to a second aspect of the present invention, a carbonaceous material precursor is provided, prepared by any one of the methods described above. Further, the carbonaceous material precursor comprises a carbon skeleton composed of a six-membered carbon ring and / or a furan ring, the carbon skeleton being connected to a plurality of oxygen-containing functional groups, wherein the six-membered carbon ring is a six-membered oxygen-containing heterocycle. The carbonaceous material precursor of the present invention features a rigid carbon skeleton that is not easily collapsed at high temperatures, capable of supporting the porous structure formed by the decomposition of oxygen-containing functional groups, preventing pore closure, and ensuring that the material possesses high mechanical strength and a stable pore structure.

[0024] According to a third aspect of the present invention, an application of the above-mentioned carbonaceous material precursor in the preparation of porous carbon, carbon microspheres, carbon quantum dots or catalyst supports is provided. Based on the thermal stability of the carbon skeleton, oxygen-containing functional groups are used to achieve pore formation, surface modification and active site construction. It can exhibit comprehensive performance superior to traditional carbon materials in the four high-value-added carbon material fields of preparing porous carbon, carbon microspheres, carbon quantum dots or catalyst supports. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a carbon skeleton of the present invention; Figure 2 This is a schematic diagram of the structure of the carbonaceous material precursor in Example 3; Figure 3 This is a schematic diagram of the structure of the carbonaceous material precursor in Example 2; Figure 4 This is a schematic diagram of the structure of the carbonaceous material precursor in Example 4; Figure 5 This is a schematic diagram of the Raman spectroscopy characterization results of Experiment Example 1. Detailed Implementation

[0026] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention. Example 1

[0027] According to one aspect of this embodiment, a method for preparing a structurally designable carbonaceous material precursor is provided, comprising the following steps: Step 1: Determine the reaction medium and reaction temperature T Based on the expected structure of the carbonaceous material, the reaction medium and reaction temperature T are determined. The reaction medium is a molten salt system formed by a metal halide and its water of crystallization, namely metal halide·nH2O. In this embodiment, the metal halide is selected from at least one of calcium chloride, calcium bromide, lithium chloride, lithium bromide, zinc chloride, zinc bromide, ferric chloride, cobalt chloride, aluminum chloride, tin chloride, ruthenium chloride, and nickel chloride. The structure of the carbonaceous material precursor includes the shape of the carbon skeleton and the degree of order of the carbon skeleton. The shape of the carbon skeleton includes porous sponge-like, aggregated, or aggregated particles embedded in a porous sponge-like matrix. The aggregated state includes irregular aggregated, spherical aggregated, or ellipsoidal aggregated.

[0028] Specifically: (1) Determine the carbon skeleton shape and the degree of order of the carbon skeleton of the carbon material precursor to be obtained. The degree of order of the carbon skeleton (characterized by Raman spectroscopy IG / ID value) can be selected from the expected value in a wide range of IG / ID values ​​from 1.0 to >2.0.

[0029] (2) Determine the acidity and water activity of the molten salt system based on the shape and order of the carbon skeleton. The acidity and water activity of the molten salt system can determine the order of the precursor carbon skeleton. (2-1) If Lewis acid is strong, a precursor with a higher degree of order will be generated. The acidity and alkalinity of the molten salt system are determined by the cations in the metal halide. The cations are determined based on the acidity and alkalinity of the molten salt system. For example, Lewis acid is strong in the AlCl3 molten salt system. (2-2) The water activity of the molten salt system depends on the crystal water content, i.e. the n value. If the n value is small, the dehydration driving force is strong, and a highly disordered carbonaceous material precursor will be generated.

[0030] (3) Determine the reaction temperature T, which is 100-220°C. The higher the temperature, the better the agglomeration effect of the carbonaceous material precursor, forming a spherical agglomerated carbon skeleton; the lower the temperature, the more porous sponge-like carbon skeleton is formed. For example, it has been experimentally determined that the product density increases at 160°C and the surface begins to become smooth; the product at 180°C transforms into a regular, dense spherical or blocky structure; and the product at 200°C evolves into highly dense, smooth spherical / ellipsoidal carbonaceous particles.

[0031] The second step involves adding an initial carbon source to initiate a polycondensation reaction. An initial carbon source is added to the reaction medium determined in the first step above. The initial carbon source is selected from cellulose or hemicellulose, and the mass of the initial carbon source is 1-15 wt% of the mass of the reaction medium. The initial carbon source is catalyzed by the reaction medium at the reaction temperature T for 5 hours. If it is expected to generate an aggregated carbon skeleton, a shaping carbon source is introduced. The shaping carbon source is glucose, fructose, or furfural. Preferably, the furfural is 5-hydroxymethylfurfural, which significantly promotes the formation of a regular, dense spherical or near-spherical morphology of the precursor. The high reactivity of the three functional groups of furan ring, aldehyde group, and hydroxymethyl group in the 5-hydroxymethylfurfural molecule, the etherification / condensation reaction constructs the basic polymer chain, and the ring-opening reaction increases the diversity of structure. The formation process is a process driven by multiple reaction mechanisms and gradually evolves from a soluble oligomer to an insoluble polymer.

[0032] The third step is catalyst regulation. During the reaction, an acid can be selectively added as a catalyst (such as HCl or AlCl3). Brønsted acids (such as HCl) tend to catalyze the formation of highly disordered precursors, while Lewis acids (such as AlCl3) are more conducive to the formation of structures with higher order.

[0033] Step 4, Post-processing After the reaction is complete, the mixture is cooled, the solid product is separated by filtration or centrifugation, and washed with deionized water and organic solvents (such as ethanol) to remove residual molten salts and soluble substances. Finally, it is dried to obtain carbonaceous material precursors humin or huminoids with designable structures.

[0034] According to a second aspect of this embodiment, a carbonaceous material precursor prepared by the above method is provided, the carbonaceous material precursor comprising a carbon skeleton composed of a six-membered carbon ring and / or a furan ring, the carbon skeleton being connected to a plurality of oxygen-containing functional groups, wherein the six-membered carbon ring is a six-membered oxygen-containing heterocycle.

[0035] According to a third aspect of this embodiment, an application of the above-mentioned carbonaceous material precursor in the preparation of porous carbon, carbon microspheres, carbon quantum dots or catalyst supports is provided. Based on the thermal stability of the carbon skeleton, oxygen-containing functional groups are used to achieve pore formation, surface modification and active site construction. It can exhibit comprehensive performance superior to traditional carbon materials in the four high-value-added carbon material fields of porous carbon, carbon microspheres, carbon quantum dots or catalyst supports. Example 2: Preparation of porous, sponge-like, low-order carbonaceous material precursors

[0036] The carbonaceous material precursor to be prepared in this embodiment has a target structure of a porous, sponge-like carbon framework with low order (Raman spectral IG / ID value <1.4), making it suitable for the field of catalytic supports. The specific steps are as follows: Step 1: Determine the reaction medium and reaction temperature T Based on the expected porous, sponge-like, low-order carbon framework structure, the pH of the molten salt system was determined to be neutral with low water activity, and the reaction temperature T was determined to be 120℃. The lower temperature favors the formation of the porous, sponge-like structure. Based on the neutral pH and low water activity of the molten salt system, the cation in the reaction medium was determined to be Ca. 2+ A neutral molten salt system is formed with a water content of n=2. The small value of n indicates low water activity, which can inhibit the orderly aggregation of carbon source molecules and generate a low-order structure. The reaction medium is a molten salt system formed by CaCl2·2H2O.

[0037] Step 2: Add the initial carbon source to carry out the polycondensation reaction. The initial carbon source cellulose was added to the above reaction medium. The mass of the initial carbon source was 8 wt% of the mass of the reaction medium. The system was heated to 120°C and reacted for 3 hours under the catalysis of the reaction medium to carry out a polycondensation reaction to generate a carbon skeleton precursor.

[0038] Step 3: Catalyst Regulation During the reaction, Brønsted acid HCl is added as a catalyst to further catalyze the formation of a highly disordered carbon framework structure, which meets the target requirement of low order.

[0039] Step 4: Post-processing After the reaction was completed, the mixture was cooled to room temperature, and the solid product was separated by centrifugation. It was first washed three times with deionized water and then twice with ethanol to remove residual molten salt and soluble substances. Then it was vacuum dried at 80°C for 6 hours to obtain a porous, sponge-like, low-order carbonaceous material precursor.

[0040] Step 5: Application The carbonaceous material precursor prepared above was used to prepare a catalyst support. Its abundant porous structure can effectively load catalytically active components and improve the catalytic efficiency of the catalyst. Characterization showed that the carbon skeleton of the carbonaceous material precursor is a typical porous sponge with a uniform pore size distribution (2-50 nm). The Raman spectrum IG / ID value is 1.22. The carbon skeleton is a six-membered carbon ring, which is a six-membered oxygen-containing heterocycle with several oxygen-containing functional groups attached to the surface, which is consistent with the expected target structure. Example 3: Preparation of spherical aggregated, highly ordered carbonaceous material precursors

[0041] The carbonaceous material precursor prepared in this embodiment has a target structure of spherical aggregated carbon framework with high carbon framework order (Raman spectral IG / ID value = 1.6-2.0), and is suitable for the preparation of carbon microspheres. The specific steps are as follows: Step 1: Determine the reaction medium and reaction temperature T Based on the expected spherical, aggregated, and highly ordered carbon skeleton structure, the acidity and alkalinity of the molten salt system were determined to be acidic with high water activity, and the reaction temperature T was determined to be 200℃ (high temperature is conducive to the formation of aggregated structures, and 200℃ can form highly dense, smooth-surfaced spherical particles). According to the acidity and high water activity of the molten salt system, the cation of the reaction medium was determined to be Al³⁺ to form an acidic molten salt system, which is conducive to the ordered arrangement of carbon source molecules. The water of crystallization content n=8 (a relatively large n value indicates high water activity, promoting the ordered formation of the carbon skeleton), and the reaction medium was determined to be a molten salt system formed by AlCl₃·8H₂O.

[0042] Step 2: Add the initial carbon source and the shaping carbon source to carry out the polycondensation reaction. The initial carbon source hemicellulose was added to the above reaction medium. The initial carbon source was loaded at 12 wt% in the reaction medium. The system was heated to 200°C and reacted under the catalysis of the reaction medium. During the polycondensation reaction, the shaping carbon source 5-hydroxymethylfurfural was introduced to promote the formation of regular spherical aggregates of carbon skeleton. The reaction time was 5 hours, and a spherical aggregated carbon skeleton precursor was generated.

[0043] Step 3: Post-processing After the reaction was completed, the mixture was cooled to room temperature, and the solid product was separated by filtration. It was first washed four times with deionized water and then twice with ethanol to remove residual molten salt, shaping carbon source residue and soluble matter. Then it was vacuum dried at 100°C for 4 hours to obtain a spherical agglomerated carbonaceous material precursor with high order.

[0044] Step 4: Application The carbonaceous material precursor prepared above was used to prepare carbon microspheres. Its regular spherical structure and highly ordered carbon skeleton can improve the conductivity and mechanical stability of the carbon microspheres, making it suitable for energy storage. Characterization showed that the carbon skeleton of the carbonaceous material precursor was a highly dense, smooth-surfaced spherical aggregate with a uniform particle size distribution (500 nm-2 μm). The Raman spectral IG / ID value was 1.75. The carbon skeleton was mainly composed of furan rings with a small number of oxygen-containing functional groups attached to the surface, which is consistent with the expected target structure. Example 4: Preparation of a moderately ordered carbonaceous material precursor with an agglomerated particle-embedded porous sponge-like composite structure.

[0045] The carbonaceous material precursor prepared in this embodiment has a target structure of aggregated particles embedded in a porous sponge-like matrix, with moderate carbon framework order (Raman spectral IG / ID value = 1.4-1.6), making it suitable for porous carbon preparation, balancing pore structure and molding performance. The specific steps are as follows: Step 1: Determine the reaction medium and reaction temperature T Based on the expected composite structure and moderately ordered carbon framework, the pH of the molten salt system was determined to be weakly acidic with moderate water activity, and the reaction temperature T was determined to be 160℃ (160℃ increases the density of the product while retaining some porous structure, forming a composite morphology). Based on the weakly acidic and moderately water-active properties of the molten salt system, the cation in the reaction medium was determined to be Zn. 2+ A weakly acidic molten salt system is formed, with a crystal water content of n=5 (n value is moderate, water activity is moderate, and the degree of order control is moderate), and the reaction medium is a molten salt system formed by ZnCl2·5H2O.

[0046] Step 2: Add the initial carbon source and the shaping carbon source to carry out the polycondensation reaction. An initial carbon source (cellulose and hemicellulose mixed at a mass ratio of 1:1) was added to the above reaction medium. The initial carbon source was loaded at 5 wt% in the reaction medium. The system was heated to 160°C and reacted for 2 hours under the catalysis of the reaction medium. During the reaction, glucose, a shaping carbon source, was introduced, causing some of the carbon source to form aggregated particles that were embedded in the porous sponge-like matrix, generating a composite carbon skeleton precursor.

[0047] Step 3: Post-processing After the reaction was completed, the mixture was cooled to room temperature, and the solid product was separated by centrifugation. It was first washed three times with deionized water and then twice with ethanol to remove residual molten salt, remnants of the shaping carbon source and soluble substances. Then it was vacuum dried at 90°C for 5 hours to obtain a carbonaceous material precursor with a porous sponge-like composite structure of agglomerated particles and medium order.

[0048] Step 4: Application The carbonaceous material precursor prepared above was used to prepare porous carbon. Its composite structure combines abundant pore structure and good formability, improving the adsorption capacity and mechanical strength of porous carbon, making it suitable for adsorption separation. Characterization showed that the carbonaceous material precursor is a composite structure of aggregated particles (irregular aggregates, particle size 100-500 nm) embedded in a porous sponge-like matrix. The Raman spectrum IG / ID value is 1.53. The carbon skeleton is composed of a six-membered carbon ring and a furan ring, with oxygen-containing functional groups such as hydroxyl and carbonyl groups attached to the surface, which is consistent with the expected target structure. Example 5: Preparation of multi-level porous carbonaceous material precursors using a mixed molten salt system

[0049] This embodiment uses a molten salt system formed by a mixed metal halide of LiCl, ZnCl2, and CaCl2 and its water of crystallization as the reaction medium. It utilizes the synergistic catalysis and in-situ pore-forming effect of multiple metal cations to prepare a carbon precursor with a hierarchical porous structure. This precursor is suitable for high-performance porous carbon, catalyst supports, and other fields.

[0050] Step 1: Determine the reaction medium and reaction temperature T Based on the expected hierarchical porous structure and moderately ordered carbonaceous material precursor, the reaction medium was determined to be a mixed molten salt system of (LiCl+ZnCl2+CaCl2)·8H2O. The molten salt system is weakly acidic with moderate water activity, and the reaction temperature is T=180 ℃.

[0051] Step 2: Add the initial carbon source and proceed with the reaction. An initial carbon source, a 1:1 mass ratio mixture of cellulose and hemicellulose, was added to the above-mentioned mixed molten salt system, and the loading of the initial carbon source in the reaction medium was controlled at 7.5 wt%. The temperature was raised to 180 ℃, and the reaction was carried out for 2.5 h under the synergistic catalytic effect of the mixed molten salt. Glucose was introduced as a shaping carbon source, and cellulose and hemicellulose generated a hierarchical porous carbonaceous material precursor under the synergistic effect of mixed cations.

[0052] Step 3: Post-processing After the reaction was completed, the mixture was cooled to room temperature, and solid-liquid separation was performed by centrifugation. The mixture was washed with deionized water and then washed twice with ethanol. After vacuum drying at 80 °C for 6 h, a multi-level porous carbonaceous material precursor was obtained.

[0053] Step 4: Application The hierarchical porous carbonaceous material precursor obtained in this embodiment can be used to prepare: high-loading catalyst supports, high-adsorption-capacity porous carbon, and high-rate-performance electrode carbon materials. Characterization showed that the carbonaceous material precursor exhibited a composite hierarchical porous morphology with agglomerated particles embedded in a porous sponge-like matrix; the Raman spectrum showed IG / ID=1.45, indicating moderate order in the carbon skeleton, consistent with the expected structure. The carbon skeleton is composed of six-membered oxygen-containing heterocycles and furan rings, and the surface is rich in oxygen-containing functional groups such as hydroxyl and carboxyl groups. Experimental Example 1

[0054] Three hydrate molten salts, namely LiCl·8H2O, ZnCl2·8H2O and CaCl2·8H2O, were prepared in 30 mL each. 2.0 g of glucose was added to each salt. The initial carbon source loading in the reaction medium was 6.25 wt%. The reaction was carried out at 140°C with magnetic stirring for 1.5 hours. The three carbonaceous material precursors were obtained after post-reaction treatment.

[0055] Raman spectroscopy characterization of it (e.g.) Figure 5 As shown in the figure, the CaCl2 system sample had the highest IG / ID value (approximately 3.2), indicating the highest degree of order in its carbon framework; the LiCl system sample had the lowest IG / ID value (approximately 1.1), indicating the most disordered structure; the ZnCl2 system was in between (approximately 1.40). This experimental example demonstrates that the degree of order in the nanoscale carbon framework of carbon material precursors can be controlled by selecting different reaction media. Experiment Example 2

[0056] Take 30 mL of CaCl2·8H2O molten salt and add 2.0 g of cellulose. React at 140°C, 160°C, 180°C and 200°C for 1.5 hours respectively to obtain four carbon material precursor samples.

[0057] SEM characterization results showed that the product at 140°C was a loose, porous, irregular sponge-like aggregate; at 160°C, the product became denser and the surface began to smooth; at 170°C, the product contained partially aggregated particles or aggregated particles embedded in a porous sponge matrix; at 180°C, the product transformed into a regular, dense, spherical or blocky structure; and at 200°C, the product completely evolved into highly dense, smooth spherical / ellipsoidal carbonaceous particles. This experimental example demonstrates that reaction temperature can regulate the microstructure of carbonaceous material precursors. Experimental Example 3:

[0058] Two sets of experiments were set up, both using CaCl2·8H2O as the medium, reacting at 140°C for 1.5 hours, and using 5-hydroxymethylfurfural as the morphology directing agent.

[0059] Group A: Only cellulose is added for polycondensation reaction.

[0060] Group B: Add 1. cellulose, and introduce the shaping carbon source 5-hydroxymethylfurfural during the polycondensation reaction.

[0061] SEM characterization showed that the products of group A were mainly dense aggregates, while the products of group B generated a large number of carbon microspheres with uniform size and smooth surface. This experimental example proves that the introduction of shaping carbon source as morphology directing agent can improve the morphology of carbon precursor.

[0062] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by any combination of the above-described technical features or their equivalents without departing from the inventive concept. For example, the above features may have similar functions to (but are not limited to) those disclosed in this application.

Claims

1. A method for producing a structurally designable carbonaceous material precursor, characterized by, Includes the following steps: Based on the expected structure of the carbonaceous material, the reaction medium and reaction temperature T are determined. The reaction medium is a molten salt system formed by a metal halide and its water of crystallization. An initial carbon source, wherein the initial carbon source is cellulose and / or hemicellulose, is added to the reaction medium. After the initial carbon source is catalyzed by the reaction medium at a reaction temperature T for 0.5-5 hours, solid-liquid separation is performed to obtain a solid carbonaceous material precursor. The reaction temperature T is 100-220℃.

2. The method of claim 1, wherein the structural designable carbonaceous material precursor is prepared by the steps of: (a) mixing a carbon source and a binder to form a mixture; (b) molding the mixture into a desired shape; (c) drying the mixture; and (d) carbonizing the mixture. The structure of the carbonaceous material precursor includes the shape of the carbon skeleton and the degree of order of the carbon skeleton. The shape of the carbon skeleton includes porous sponge-like, aggregated, or aggregated particles embedded in a porous sponge-like matrix. The aggregated state includes irregular aggregated, spherical aggregated, or ellipsoidal aggregated.

3. The method of claim 1, wherein the structural designable carbonaceous material precursor is prepared by the steps of: (a) mixing a carbon source and a binder to form a mixture; (b) molding the mixture into a desired shape; (c) drying the mixture; and (d) carbonizing the mixture. Based on the expected structure of the carbonaceous material, determine the reaction medium and reaction temperature T, including: based on the expected structure of the carbonaceous material, determine the acidity / alkalinity, water activity, and reaction temperature T of the molten salt system, and determine the cation and water of crystallization content of the reaction medium based on the acidity / alkalinity and water activity of the molten salt system.

4. The method of producing a structurally designable carbonaceous material precursor according to claim 1 or 3, characterized by, Based on the expected structure of the carbonaceous material, determine the reaction medium and reaction temperature T, including: To obtain carbonaceous materials with high carbon skeleton order, an acidic reaction medium with high water activity is selected; to obtain carbonaceous materials with low carbon skeleton order, a neutral reaction medium with low water activity is selected. The goal is to obtain carbonaceous materials with an aggregated carbon skeleton, with a reaction temperature T in the range of 160-220°C.

5. The method of claim 1, wherein the structural designable carbonaceous material precursor is prepared by the steps of: (a) mixing a carbon source and a binder to form a mixture; (b) molding the mixture into a desired shape; (c) drying the mixture; and (d) carbonizing the mixture. The metal halide is selected from at least one of calcium chloride, calcium bromide, lithium chloride, lithium bromide, zinc chloride, zinc bromide, ferric chloride, cobalt chloride, aluminum chloride, tin chloride, ruthenium chloride, and nickel chloride. And / or the reaction medium is a metal halide·nH2O, where the value of n ranges from 2 to 10; And / or the mass of the initial carbon source is 1-15 wt% of the reaction medium.

6. The method of claim 1, wherein the structural designable carbonaceous material precursor is prepared by a method comprising: mixing a carbon source and a binder to form a mixture; and molding the mixture to form a precursor. After adding an initial carbon source to the reaction medium, a shaping carbon source is introduced, wherein the shaping carbon source is glucose, fructose or furfural; preferably, the furfural is 5-hydroxymethylfurfural.

7. The method for preparing a structurally designable carbonaceous material precursor according to claim 1, characterized in that, A catalyst is added to the reaction medium, wherein the catalyst is a Brønsted acid or a Lewis acid.

8. A carbonaceous material precursor, characterized by, It is prepared by the method described in any one of claims 1-7.

9. The carbonaceous material precursor according to claim 8, characterized in that, The carbonaceous material precursor comprises a carbon skeleton composed of a six-membered carbon ring and / or a furan ring, wherein the carbon skeleton is connected to a plurality of oxygen-containing functional groups, and the six-membered carbon ring is a six-membered oxygen-containing heterocycle.

10. The application of the carbonaceous material precursor according to claim 8 or 9 in the preparation of porous carbon, carbon microspheres, carbon quantum dots or catalyst supports.

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