A pore size control method of resin carbon microspheres and a microporous resin carbon microsphere

Abstract

This invention discloses a method for controlling the pore size of resin carbon microspheres and a microporous resin carbon microsphere, relating to the field of porous carbon materials technology. It solves the problems of complex processes, strong corrosiveness, poor structural stability, and severe environmental pollution in existing methods for constructing microporous carbon materials, as well as the difficulty in controlling the pore structure during the preparation of porous carbon materials based on carbohydrate-based carbon materials. The invention involves mixing mesoporous resin carbon microspheres with a carbohydrate compound solution, followed by stirring, ultrasonication, and drying; subsequently, a heating carbonization treatment is performed. During carbonization, the carbohydrate compound generates amorphous carbon, and the pyrolysis products effectively fill or cover the mesopores, forming new micropores when the pyrolysis gases escape, thus obtaining microporous resin carbon microspheres. This invention achieves an effective transformation of resin carbon microspheres from mesoporous to microporous, and significantly increases the micropore content of the microporous resin carbon microspheres (up to 89%), making it applicable to small molecule adsorption, supercapacitor electrode materials, and catalyst supports.

Description

Technical Field

[0001] This invention relates to the field of porous carbon materials technology, specifically to a method for controlling the pore size of resin carbon microspheres and a microporous resin carbon microsphere. Background Technology

[0002] Porous carbon materials have long attracted attention in fields such as adsorption separation, electrochemical energy storage, and catalysis due to their high specific surface area, tunable pore structure, and excellent chemical stability. Especially in batteries and supercapacitors, pore structure directly affects ion transport and charge storage behavior. Mesopores (2–50 nm) facilitate electrolyte diffusion, while micropores (<2 nm) provide higher specific surface area and active sites. Therefore, achieving precise control of pore structure within the same carbon material system, particularly the transformation from mesopores to micropores while maintaining existing structural advantages, has become an important research direction in the field of porous carbon materials.

[0003] In existing technologies, the construction of microporous carbon materials mainly relies on two major technical routes: template method and chemical activation method. The template method typically includes hard template method and soft template method. The hard template method requires first introducing an inorganic template such as silica, then removing the template through high-temperature carbonization and subsequent acid etching to obtain the microporous structure. However, this method involves multiple steps such as template preparation, composite, carbonization, and etching, making the process complex. Furthermore, the template removal process often requires the use of highly corrosive reagents, such as hydrofluoric acid, which not only poses a serious threat to operator safety but also easily causes irreversible environmental pollution. Simultaneously, the carbon framework is easily eroded during etching, leading to a decrease in structural integrity or even collapse, thus affecting the stability and repeatability of material properties. In contrast, while the soft template method can avoid highly corrosive etching steps to some extent, problems such as incomplete template removal and difficulty in precisely controlling the ordered pore structure still exist. The chemical activation method is another commonly used approach, which uses activators such as KOH and ZnCl2 to react with the carbon precursor under high-temperature conditions to generate a large number of microporous structures. While this method can achieve a relatively high specific surface area to some extent, the activator is highly corrosive, causing severe corrosion to the reaction equipment under high-temperature conditions, increasing the cost of industrial applications. Furthermore, over-activation can lead to excessive etching of the carbon framework, resulting in structural collapse and a significant decrease in the material's mechanical strength and cycle stability. In addition, inorganic impurities introduced during activation are difficult to remove completely, requiring extensive subsequent water washing or acid pickling, which is not only cumbersome but also imposes a significant environmental burden.

[0004] In recent years, with the development of green chemistry concepts, the preparation of porous carbon materials using biomass resources has gradually become a research hotspot. For example, methods for preparing porous carbon materials using natural sugars such as starch (e.g., Chinese invention patent CN104045074A) and sucrose as carbon sources through direct carbonization or combined with template methods and activation methods have been widely reported. These methods have certain advantages in terms of raw material sources and sustainability, but they still have significant shortcomings in terms of structure control. First, sugars are prone to melting and agglomeration during heat treatment, making it difficult to maintain a stable spherical structure. They usually require complex pre-forming processes such as spray drying or emulsion polymerization, resulting in lengthy processes, high costs, and stringent equipment requirements. Secondly, existing technologies for preparing carbohydrate-based carbon materials mostly involve constructing carbon structures from molecular or oligomer precursors, meaning they primarily focus on synthesizing carbon materials from scratch. In terms of pore size distribution control, they mainly rely on templates or activation processes, making it difficult to achieve an effective transformation from mesopores to micropores while maintaining the original morphology and framework stability. Even with post-processing methods such as activation or etching, problems such as particle breakage, specific surface area loss, or disordered pore structure often arise, making it difficult to meet the dual requirements of high-performance carbon materials in terms of fine pore structure and stability, thus limiting their application in fields requiring specific pore structures. Summary of the Invention

[0005] To address the problems of complex processes, strong corrosivity, poor structural stability, and severe environmental pollution in existing methods for constructing microporous carbon materials, as well as the difficulty in controlling the pore structure during the preparation of porous carbon materials based on carbohydrate-based carbon materials, this invention proposes a method for controlling the pore size of resin carbon microspheres and a microporous resin carbon microsphere. The technical solution of this invention is as follows: A method for controlling the pore size of resin carbon microspheres, from mesoporous resin carbon microspheres to microporous resin carbon microspheres, includes the following steps: Mesoporous resin carbon microspheres are mixed with a sugar compound solution, stirred, sonicated, and dried; then subjected to a heating carbonization treatment; during the carbonization process, the sugar compound can generate amorphous carbon, and the pyrolysis products can effectively fill or cover the mesopores, and form new micropores when the pyrolysis gas escapes, thus obtaining microporous resin carbon microspheres.

[0006] The specific surface area of ​​the mesoporous resin carbon microspheres is 800~3000 m². 2 / g; the pore volume of the mesoporous resin carbon microspheres accounts for more than 50% of the total pore volume; the mesoporous resin carbon microspheres were purchased from Shandong Senjiu Biomaterials Co., Ltd., specifically model SG-7U mesoporous resin carbon microspheres. The average pore diameter of the mesoporous resin carbon microspheres is 2~3.2 nm, wherein the average pore diameter = 4 × (total pore volume / specific surface area).

[0007] The specific surface area of ​​the microporous resin carbon microspheres is 800~3000 m². 2 / g; the pore volume of the microporous resin carbon microspheres accounts for more than 80% of the total pore volume. The average pore diameter of the microporous resin carbon microspheres is 1.7~1.9 nm.

[0008] The heating and carbonization process is carried out in stages. The first stage involves heating from room temperature to 100-300°C in an air atmosphere at a rate of 1-10°C / min, with a holding time of 0.5-2 hours. This stage is mainly used for pre-oxidation and stabilization of carbohydrate compounds. With the participation of oxygen, a mild oxidation and cross-linking reaction is promoted, forming a relatively stable carbon precursor. This avoids rapid decomposition or violent shrinkage during subsequent high-temperature carbonization, which could lead to pore structure collapse or uncontrolled distribution. The heating rate and temperature have a significant impact on the uniformity and controllability of the reaction process. If the heating rate is below 1°C / min, the overall processing cycle is significantly prolonged, which is detrimental to process efficiency. If it is above 10°C / min, the temperature difference between the inside and outside of the system increases, easily causing uneven reaction or local overheating, affecting structural stability. When the temperature is below 100°C, carbohydrate oxidation and structural rearrangement are insufficient, making it difficult to form a stable precursor. When the temperature is above 300°C, excessive oxidation of the carbon microspheres may occur, leading to damage to the skeletal structure.

[0009] The second stage involves heating from the first stage temperature to 400-900℃ in an inert gas atmosphere at a rate of 2-10℃ / min, with a holding time of 1-3 hours. In this oxygen-deficient environment, the sugar-stabilized precursor formed in the first stage undergoes pyrolysis and carbonization simultaneously with the carbon microsphere matrix. The carbon derived from the sugar is deposited in situ on the pore walls and inside the pores, narrowing and segmenting the original mesoporous structure and inducing the formation of new micropores, thereby achieving the transformation of pore size from mesopores to micropores. Controlling the heating rate at 2-10℃ / min helps regulate the volatile release rate during pyrolysis, preventing pore damage or structural collapse caused by a large amount of instantaneous gas release. Too low a heating rate is detrimental to improving process efficiency, while too high a rate can easily cause localized thermal stress concentration, affecting the uniformity of the pore structure. The carbonization temperature range is 400~900℃. When the temperature is below 400℃, the carbonization reaction is insufficient, the degree of carbon deposition is limited, and it is difficult to form an effective microporous structure. When the carbonization temperature is above 900℃, it may induce densification or local graphitization of the carbon material, leading to micropore shrinkage or even disappearance, thereby reducing the specific surface area and the proportion of micropores. Setting the holding time to 1~3 h is beneficial to ensure that the carbonization reaction proceeds fully, allowing the pore structure to gradually stabilize and tend to be uniform. In the second stage, it is preferable to raise the temperature to 700~800℃ and the preferred holding time is 1~2 h. Within this range, the degree of carbonization is moderate, the micropores are fully developed, the specific surface area is high, and the structural stability is good.

[0010] Furthermore, the carbohydrate compound is one or more of monosaccharides, disaccharides, and polysaccharides.

[0011] Furthermore, the monosaccharide is one or more of glucose, fructose, and galactose; the disaccharide is one or more of sucrose, lactose, and maltose; and the polysaccharide is one or more of starch, cellulose, and chitin. All of the above-mentioned sugar compounds can be fully dissolved in water and uniformly dispersed in the system. During the subsequent carbonization process, they are transformed in situ into amorphous carbon within the mesoporous structure and uniformly deposited inside the pores, thereby achieving effective control over the pore size structure. At the same time, the destruction of the original carbon microsphere framework structure is avoided, which is conducive to achieving the transformation from mesoporous to microporous while maintaining the spherical morphology and structural stability.

[0012] Furthermore, the mass concentration of the carbohydrate compound solution is 5% to 30%, which directly determines the uniformity of the carbohydrate compound distribution within the carbon microsphere channels and the effect of pore structure regulation. When the mass concentration is below 5%, the effective carbon source content in the system is insufficient, making it difficult to form continuous or sufficient carbon deposition within the mesoporous structure, resulting in limited micropore formation and low pore structure conversion efficiency. When the concentration is above 30%, the solution viscosity increases significantly, permeability decreases, which is not conducive to entering the internal channels of the microspheres. It is easy to form local enrichment or excessively thick coating layers on the particle surface, thereby hindering the effective regulation of internal pores and potentially causing particle adhesion or agglomeration, affecting the material dispersion and structural uniformity. The mass concentration of the carbohydrate compound solution is preferably 10% to 20%. Within this range, the viscosity of the carbohydrate compound solution is moderate and it has good permeability, which can ensure sufficient carbon source loading and facilitate the uniform entry of carbohydrate molecules into the mesoporous structure. This enables uniform in-situ carbon deposition during the subsequent carbonization process, thereby achieving efficient and controllable adjustment of the pore size structure and maintaining the overall morphological integrity and structural stability of the carbon microspheres.

[0013] The mass ratio of mesoporous resin carbon microspheres to carbohydrate compounds is 1:0.5 to 1:5. This mass ratio range has a decisive influence on the loading degree of carbohydrates in the channels and the transformation effect of pore structure. When the mass ratio is less than 1:0.5, the content of carbohydrate compounds in the system is insufficient, making it difficult to form continuous and sufficient carbon deposition in the mesoporous structure, resulting in incomplete pore modification, limited micropore formation, and insignificant overall pore structure control effect. When the mass ratio is greater than 1:5, the content of carbohydrate compounds is excessive, which easily leads to excessive carbon deposition in the channels and particle surfaces during carbonization, thereby causing pore blockage, resulting in a decrease in effective specific surface area, and increasing raw material consumption, which is detrimental to process economy. The preferred mass ratio of mesoporous resin carbon microspheres to carbohydrate compounds is 1:1. Under this ratio, the carbohydrate compounds can fully enter and uniformly distribute within the mesoporous structure, achieving effective in-situ carbon deposition during carbonization, thereby promoting the transformation of mesopores into micropores. At the same time, it can avoid pore blockage or surface coating caused by excessive deposition, achieving a good balance between pore structure optimization and material utilization efficiency.

[0014] Furthermore, the stirring time is 1-6 hours to ensure that the solution fully impregnates the pores of the mesoporous carbon microspheres, laying the foundation for uniform pore control during the subsequent carbonization process. Too short a stirring time will result in insufficient wetting; too long a stirring time will lead to low efficiency and may cause partial degradation of carbohydrate compounds in the solution.

[0015] Furthermore, the frequency of the ultrasound is 100 kHz; the duration of the ultrasound is 60 min.

[0016] Furthermore, the drying temperature is 60-100℃, and the drying time is 6-48 h. This drying process aims to gently remove moisture from the system, inhibit the migration and accumulation of carbohydrate compounds on the particle surface during solvent evaporation, thereby promoting their uniform distribution within the carbon microsphere channels and providing a stable precursor state for the controllable evolution of the pore structure in the subsequent carbonization stage. When the drying temperature is below 60℃, the moisture removal rate is slow, resulting in low overall drying efficiency, which is not conducive to industrial implementation. When the temperature is above 100℃, premature pyrolysis or crystallization of carbohydrates may be induced, leading to uneven distribution within the channels and affecting the uniformity of subsequent pore structure regulation. When the drying time is less than 6 h, moisture is likely to remain in the system, which may cause violent vaporization during subsequent heating and carbonization, thereby disturbing or even destroying the pore structure. When the drying time exceeds 48 h, although there is no significant gain in structural improvement, it will significantly increase energy consumption and process costs, which is not conducive to practical applications.

[0017] The room temperature mentioned in this invention is 25°C.

[0018] Furthermore, the inert gas is one or a combination of nitrogen and argon. These inert gases are economical and readily available, and can effectively isolate oxygen and prevent the carbon materials from oxidizing and burning.

[0019] Microporous resin carbon microspheres obtained by controlling the pore size of resin carbon microspheres as described above.

[0020] One application of the above-mentioned microporous resin carbon microspheres is in the fields of small molecule adsorption, supercapacitor electrode materials, and catalyst supports.

[0021] Compared with existing technologies, this invention solves the problems of complex processes, strong corrosivity, poor structural stability, and serious environmental pollution in existing methods for constructing microporous carbon materials, as well as the difficulty in controlling the pore structure during the preparation of porous carbon materials based on carbohydrate carbon materials. The specific beneficial effects are as follows: 1. This invention introduces carbohydrate compounds as pore regulators and combines them with a segmented carbonization process. Without requiring additional templates or activators, and while maintaining the structural integrity and stability of carbon microspheres, it achieves an effective transformation of resin carbon microspheres from mesoporous (>2 nm) to microporous (<2 nm) structures, significantly increasing the micropore content of the microporous resin carbon microspheres (up to 89%). During carbonization, the carbohydrate compounds undergo pyrolysis and deposition, selectively filling and modifying the mesopore walls. Under the mesopore confinement effect, the mesopores are gradually transformed into micropores, achieving a significant shift from mesoporous (>50%) to microporous (>80%) structure, while maintaining the spherical structure and dispersibility of the carbon microspheres. This allows for precise control of the pore structure of existing mesoporous carbon microspheres. This expands the application potential of microporous resin carbon microsphere materials in adsorption, catalysis, and energy storage, and significantly improves their applicability in small molecule adsorption (such as VOCs and CO2), supercapacitor electrode materials, and catalyst supports.

[0022] 2. This invention employs a segmented heating carbonization strategy. In the first stage (100~300℃), the carbohydrate compounds undergo mild pre-oxidation and stabilization under oxygen-containing conditions, causing partial oxidative cross-linking reactions to form stable carbon precursors. This avoids rapid volatilization or severe structural shrinkage leading to pore collapse in the subsequent high-temperature stage. In the second stage (400~900℃), high-temperature carbonization is carried out in an inert atmosphere, causing simultaneous pyrolysis of the carbohydrate precursors and the carbon microsphere matrix, resulting in in-situ carbon deposition. This shrinks and segments the original mesoporous structure, while simultaneously inducing the generation and expansion of micropores. This achieves controllable transformation from pore to micropore direction and effectively improves the problems of low micropore ratio and uneven pore size distribution in existing technologies. Furthermore, this process maintains the original spherical structure and mechanical strength of the carbon microspheres, and the resulting microporous carbon microspheres have a stable structure without aggregation or deformation, making them directly usable for subsequent applications.

[0023] 3. This invention utilizes widely available raw materials, employs a simple and environmentally friendly process, and is cost-effective. Carbohydrate compounds are highly water-soluble, widely available, and inexpensive. They do not require template agents or complex post-processing steps and can be uniformly compounded with mesoporous resin carbon microspheres, fully penetrating into the pores. After drying and carbonization, a uniform carbon deposition layer is formed, suitable for large-scale industrial production. Furthermore, the carbonized product of this invention is a pure carbon material system, free from residual metal or solvent contamination. This eliminates the need for cleaning steps, simplifying the process, reducing costs, and avoiding structural damage caused by washing. It can be directly used in adsorption, electrochemistry, and other applications. This effectively solves the problems of complex processes, high equipment dependence, and severe environmental pollution in existing microporous carbon preparation technologies. Attached Figure Description

[0024] Figure 1 Scanning electron microscope image of mesoporous resin carbon microspheres; Figure 2 This is a scanning electron microscope image of microporous resin carbon microspheres. Detailed Implementation

[0025] To make the technical solutions 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. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as limiting the present invention.

[0026] Example 1. Dissolve 15 g of glucose in 100 mL of deionized water (15% by mass) and stir until completely dissolved to form a homogeneous and transparent solution; take 15 g of mesoporous resin carbon microspheres (specific surface area 3082 m²). 2 (g, with mesoporous pore volume accounting for 100% of the total pore volume) was added to a glucose solution, mechanically stirred for 4 h, and sonicated for 4 h to ensure that the glucose solution fully impregnates the pores of the carbon microspheres, resulting in a mixture. The mixture was dried in an oven at 80℃ for 12 h to obtain a precursor. The precursor was placed in a tube furnace and subjected to two stages of heating and carbonization. In the first stage, the temperature was increased from room temperature to 200℃ at a heating rate of 3℃ / min under an air atmosphere and held for 1 h. In the second stage, the temperature was increased from 200℃ to 750℃ at a heating rate of 3℃ / min under a nitrogen atmosphere and held for 2 h to obtain microporous resin carbon microspheres.

[0027] like Figure 1 The image shown is a scanning electron microscope (SEM) image of the mesoporous resin carbon microspheres in Example 1. The image reveals that the resin carbon microspheres are generally spherical with a relatively uniform particle size distribution, smooth and dense surface, and no obvious breakage or collapse. This indicates that the original material used in this invention has good structural integrity and morphological stability. Figure 2The image shows a SEM image of the microporous resin carbon microspheres. As can be seen from the image, the treated carbon microspheres still maintain a good spherical structure with a clear overall outline. No obvious aggregation or structural collapse has occurred, indicating that the pore size control method of the resin carbon microspheres provided by the present invention achieves control from mesopores to micropores, while effectively maintaining the morphology and skeleton stability of the original carbon microspheres.

[0028] Table 1 below shows the pore volume distribution of mesoporous and microporous resin carbon microspheres in different pore size ranges. Based on the data in Table 1, the original mesoporous resin carbon microspheres are predominantly mesoporous, with the pore volume in the 10–50 nm pore size range accounting for as high as 64.11%, and the 2–10 nm range accounting for 33.3%, while micropores (0.32–2 nm) account for only 1.01%, exhibiting a typical mesoporous-dominated structure. In contrast, the microporous resin carbon microspheres obtained after high-temperature carbonization of carbohydrate compounds show a significant transformation in pore structure. The proportion of micropores increases dramatically to 88.29%, becoming the dominant pore structure, while the original mesoporous structure is significantly reduced. The proportion of pores in the 2–10 nm range drops to 11.34%, and the pore volume in the 10–50 nm range is only 0.36%, with the macroporous structure essentially disappearing. This invention demonstrates that by mixing mesoporous resin carbon microspheres with a carbohydrate compound solution and then subjecting them to subsequent carbonization, an effective transformation from mesoporous to microporous structures can be achieved without destroying the original spherical structure. Furthermore, the pore structure regulation exhibits significant directionality and high conversion efficiency. This reconstruction process from mesoporous to microporous significantly increases the micropore content of the material and optimizes the pore size distribution, significantly broadening the application fields of microporous carbon materials. It can be applied to areas with strong micropore dependence, such as small molecule adsorption, supercapacitor electrode materials, and catalyst supports.

[0029] Table 1

[0030] Example 2. The difference between this embodiment and Example 1 is that the glucose concentration is 10%, while the rest of the preparation steps and conditions are the same as in Example 1, and microporous resin carbon microspheres are prepared.

[0031] Example 3. The difference between this embodiment and Example 1 is that the glucose concentration is 30%, while the rest of the preparation steps and conditions are the same as in Example 1, and microporous resin carbon microspheres are prepared.

[0032] Example 4. The difference between this embodiment and Example 1 is that the amount of mesoporous resin carbon microspheres used is 7.5 g, while the remaining preparation steps and conditions are the same as in Example 1, and microporous resin carbon microspheres are obtained.

[0033] Example 5. The difference between this embodiment and Example 1 is that the amount of mesoporous resin carbon microspheres used is 75 g, while the rest of the preparation steps and conditions are the same as in Example 1, and microporous resin carbon microspheres are obtained.

[0034] Example 6. The difference between this embodiment and Embodiment 1 is that the first stage of heating is to raise the temperature to 150°C, while the remaining preparation steps and conditions are the same as in Embodiment 1, and microporous resin carbon microspheres are prepared.

[0035] Example 7. The difference between this embodiment and Embodiment 1 is that the first stage of heating is to raise the temperature to 300°C, while the remaining preparation steps and conditions are the same as in Embodiment 1, and microporous resin carbon microspheres are prepared.

[0036] Example 8. The difference between this embodiment and Embodiment 1 is that the second stage of heating is to raise the temperature to 500°C. The remaining preparation steps and conditions are the same as in Embodiment 1, and microporous resin carbon microspheres are prepared.

[0037] Example 9. The difference between this embodiment and Embodiment 1 is that the second stage of heating is to raise the temperature to 900°C. The remaining preparation steps and conditions are the same as in Embodiment 1, and microporous resin carbon microspheres are obtained.

[0038] Example 10. The difference between this embodiment and Example 1 is that the sugar compound is fructose, while the rest of the preparation steps and conditions are the same as in Example 1, and microporous resin carbon microspheres are prepared.

[0039] Comparative Example 1. The difference between this comparative example and Example 1 is that glucose is not added, and the mesoporous resin carbon microspheres are directly subjected to heating carbonization treatment. The remaining steps are the same as in Example 1 to obtain carbon microsphere material.

[0040] Comparative Example 2. The difference between this comparative example and Example 1 is that the first stage of heating and carbonization is omitted, and the second stage of heating and carbonization is performed directly. The remaining steps are the same as in Example 1, resulting in microporous resin carbon microspheres.

[0041] Nitrogen adsorption-desorption tests were performed on the samples prepared in Examples 1-10 and Comparative Examples 1-2. The specific surface area and micropore volume ratio are shown in Table 2 below. As can be seen from the table, each example, by introducing carbohydrate compounds and combining them with a segmented carbonization process, achieved an effective transformation from mesoporous to microporous structures while maintaining the structural stability of the carbon microspheres, and significantly increased the micropore volume ratio of the microporous resin carbon microspheres. Among them, the microporous resin carbon microspheres prepared in Example 1 exhibited excellent comprehensive performance, with a specific surface area reaching 2590 m².2 / g, with a micropore volume ratio reaching 88.29%, achieving efficient micropore construction and pore structure optimization. In Example 2, after reducing the amount of carbohydrate compounds, the specific surface area slightly increased (2670 m²). 2 (g), but the micropore ratio decreased to 83%, indicating that the reduction of carbohydrates can, to some extent, avoid overfilling of pores and help maintain a high specific surface area. In Example 3, after increasing the carbohydrate content, both the specific surface area and the micropore ratio decreased, indicating that excessive carbohydrates can easily cause pore blockage or excessive surface deposition during carbonization, which in turn confirms the rationality of the carbohydrate dosage range set in this invention.

[0042] The proportion of micropores in Examples 4 and 5 of the present invention is lower than that in Example 1, indicating that insufficient carbohydrate compounds lead to inadequate pore modification, while excessive carbohydrate compounds easily lead to pore structure imbalance. This also shows that the proportion range defined by the present invention has clear technical significance and reasonable boundary.

[0043] Example 6 reduced the pre-oxidation temperature in the first stage, yet the micropore ratio still reached 83.44%, slightly lower than in Example 1, indicating that insufficient oxidation affects the structural stability of the precursor. Example 7 increased the pre-oxidation temperature in the first stage, and the micropore ratio decreased to 70.21%, indicating that excessively high temperatures may cause localized oxidation or structural damage to the carbon framework, thus affecting subsequent micropore formation. This demonstrates that the first-stage temperature control proposed in this invention plays a crucial role in forming a stable precursor structure.

[0044] Example 8 lowered the carbonization temperature of the second stage, and the micropore ratio was maintained at 83%, indicating that a certain degree of carbonization can still be achieved at a lower temperature (500°C), but there may be a risk of insufficient carbonization. Example 9 increased the carbonization temperature of the second stage, and the micropore ratio decreased to 60%, indicating that excessively high temperatures (900°C) will cause micropore shrinkage or even structural densification, thereby reducing the micropore ratio, which verifies the scientific nature and necessity of the temperature window setting of the present invention.

[0045] Example 10, using other carbohydrate compounds (fructose), also exhibited superior performance, with a specific surface area of ​​2845 m². 2The micropore content reached 89% (g), indicating that the pore size control method provided by this invention has good applicability and scalability for different sugars. In contrast, Comparative Example 1, which did not introduce sugar compounds, maintained its mesoporous structure essentially unchanged and did not form a well-developed microporous structure, demonstrating that sugar compounds are a necessary condition for achieving pore size transformation. Comparative Example 2, lacking a first-stage pre-oxidation treatment, resulted in rapid decomposition of the sugars during subsequent high-temperature carbonization, making it difficult to form a stable deposition structure within the pores, thus affecting the formation and distribution of micropores. This demonstrates that the segmented carbonization process provided by this invention plays an irreplaceable role in achieving pore size control in this invention.

[0046] Table 2

[0047] In summary, this invention, by introducing carbohydrate compounds as pore regulators and combining them with a segmented carbonization process, achieves an effective transformation of resin carbon microspheres from mesoporous (>2 nm) to microporous (<2 nm) structures without the need for additional templates or activators, while maintaining the structural integrity and stability of the carbon microspheres. It also significantly increases the micropore content of the microporous resin carbon microspheres (up to 89%). Furthermore, this invention utilizes widely available raw materials, employs a simple and environmentally friendly process, and is low in cost, making it suitable for large-scale industrial production. It effectively solves the problems of complex processes, high equipment dependence, and severe environmental pollution associated with existing microporous carbon preparation technologies.

[0048] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0049] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for controlling the pore size of resin carbon microspheres, characterized in that, The process of transforming mesoporous resin carbon microspheres into microporous resin carbon microspheres includes the following steps: Mesoporous resin carbon microspheres were mixed with a sugar compound solution, stirred, sonicated, and dried; then subjected to a heating carbonization treatment to obtain microporous resin carbon microspheres. The specific surface area of ​​the mesoporous resin carbon microspheres is 800~3000 m². 2 / g; the pore volume of the mesoporous resin carbon microspheres accounts for more than 50% of the total pore volume; The specific surface area of ​​the microporous resin carbon microspheres is 800~3000 m². 2 / g; the pore volume of the microporous resin carbon microspheres accounts for more than 80% of the total pore volume; The heating and carbonization process is carried out in stages. The first stage is to heat the temperature from room temperature to 100-300°C in an air atmosphere at a heating rate of 1-10°C / min, and hold the temperature for 0.5-2 hours. The second stage involves heating the temperature from the first stage to 400-900°C at a rate of 2-10°C / min in an inert gas atmosphere, with a holding time of 1-3 hours; the inert gas is one or a combination of nitrogen and argon.

2. The method for controlling the pore size of resin carbon microspheres according to claim 1, characterized in that, The carbohydrate compound is one or more of monosaccharides, disaccharides, and polysaccharides.

3. The method for controlling the pore size of resin carbon microspheres according to claim 2, characterized in that, The monosaccharide is one or more of glucose, fructose, and galactose; the disaccharide is one or more of sucrose, lactose, and maltose; and the polysaccharide is one or more of starch, cellulose, and chitin.

4. The method for controlling the pore size of resin carbon microspheres according to claim 3, characterized in that, The mass concentration of the carbohydrate compound solution is 5% to 30%; the mass ratio of the mesoporous resin carbon microspheres to the carbohydrate compound is 1:0.5 to 1:

5.

5. The method for controlling the pore size of resin carbon microspheres according to claim 1, characterized in that, The stirring time is 1-6 h; the ultrasonic frequency is 100 kHz; and the ultrasonic time is 60 min.

6. The method for controlling the pore size of resin carbon microspheres according to claim 1, characterized in that, The drying temperature is 60~100℃; the drying time is 6~48 h.

7. A method for controlling the pore size of resin carbon microspheres as described in any one of claims 1-6, resulting in microporous resin carbon microspheres.

8. An application of the microporous resin carbon microspheres as described in claim 7, characterized in that, It is applied in the fields of small molecule adsorption, supercapacitor electrode materials, and catalyst supports.

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