Preparation method of self-doped spherical porous carbon material with hundred-micron level
High-strength spherical porous carbon materials were prepared by suspension polymerization and carbonization, which solved the problems of insufficient strength and complex processing of chitosan materials, and achieved efficient and environmentally friendly material preparation, suitable for high-strength application fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANKAI UNIV
- Filing Date
- 2024-06-07
- Publication Date
- 2026-07-28
AI Technical Summary
In existing technologies, spherical porous carbon materials prepared using chitosan as a carbon source have poor strength, and the processing is complex, requiring a lot of reagents and energy, which limits their promotion in high-strength application fields.
A 100-micron-sized spherical chitosan precursor was prepared by suspension polymerization. The carbonization process was carried out under a protective atmosphere and heated to obtain a self-doped spherical porous carbon material with high specific surface area and high strength. The chitosan itself was used as the nitrogen source, avoiding the use of additional template agents and activators.
The prepared 100-micron-sized self-doped spherical porous carbon materials have high specific surface area, good mechanical strength and large size characteristics, making them suitable for high-strength applications. Moreover, the process is environmentally friendly and efficient, making it suitable for large-scale production.
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Figure CN118744988B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of carbon materials technology, specifically to a method for preparing a 100-micron-sized self-doped spherical porous carbon material. Background Technology
[0002] Chitosan, a naturally sourced nitrogen-containing polysaccharide, is a widely distributed renewable resource. It can also be used to prepare nitrogen-doped porous carbon in situ. The main limitation to its application is the lack of effective processing methods. Therefore, exploring simple, rapid, environmentally friendly, and low-cost processing methods is crucial for developing and realizing large-scale applications of the material (MONTEMBAULTA, et al. (2005). Rheometric study of the gelation of chitosan in aqueous solution without cross-linking agent. Biomacromolecules.). Traditional processing methods use natural polysaccharide powder as a carbon source, directly carbonizing it to obtain activated carbon powder, which is then mixed with binders and other additives for granulation. However, materials prepared in this way have poor strength and are only suitable for applications with lower strength requirements, such as water treatment (Lan, J., et al. (2023). Progress on fabrication and application of activated carbon sphere in recent decades. Journal of Industrial and Engineering Chemistry.). Summary of the Invention
[0003] In view of this, the purpose of this invention is to provide a method for preparing a 100-micron-sized self-doped spherical porous carbon material. This invention uses 100-micron-sized spherical chitosan as a precursor, which is carbonized to obtain a 100-micron-sized self-doped spherical porous carbon material. The 100-micron-sized self-doped spherical porous carbon material prepared by this invention has the advantages of high specific surface area, high strength, and large size, while solving the problems of complex doping process, high reagent consumption, and high energy consumption in existing spherical porous carbon materials.
[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0005] This invention provides a method for preparing self-doped spherical porous carbon materials at the hundred-micron scale, comprising the following steps:
[0006] Carbonization of 100-micron-sized spherical chitosan precursors yields 100-micron-sized self-doped spherical porous carbon materials.
[0007] Preferably, the method for preparing the 100-micron-sized spherical chitosan precursor includes:
[0008] Chitosan was dissolved in an aqueous acetic acid solution to obtain a dispersed phase; butyl acetate and Span 80 were mixed to obtain a continuous phase.
[0009] The dispersed phase and the continuous phase are mixed and suspended to obtain droplets of hundreds of micrometers in size; NaOH solution is added to carry out a precipitation reaction to obtain spherical chitosan precursors of hundreds of micrometers in size.
[0010] Preferably, the degree of deacetylation of the chitosan is 75-95%.
[0011] Preferably, the suspension dispersion is carried out under stirring conditions; the stirring speed is 100-500 r / min; and the suspension dispersion temperature is 10-40℃.
[0012] Preferably, the particle size of the 100-micron-sized spherical chitosan precursor is 400–600 μm; the crystallinity of the 100-micron-sized spherical chitosan precursor is 37–52%, and the average crystal region size is [missing information].
[0013] Preferably, the carbonization conditions include: first heating to 200-500°C under a protective atmosphere, and holding at that temperature for 1-5 hours; second heating to 600-1000°C, and holding at that temperature for 2-5 hours; and then naturally cooling to room temperature.
[0014] Preferably, the heating rate of the first heating is 3 to 10 °C / min; the heating rate of the second heating is 3 to 10 °C / min.
[0015] Preferably, the particle size of the self-doped spherical porous carbon material is 100–600 μm, and the specific surface area is 269–2100 m². 2 / g; average pore size is 2-4nm; micropore size is 0.6-0.8nm.
[0016] Preferably, the N content of the self-doped spherical porous carbon material at the hundred-micrometer scale is 1-4 at%.
[0017] Preferably, the single-particle crushing strength of the 100-micron-sized self-doped spherical porous carbon material is 1.78 to 3.13 N.
[0018] This invention provides a method for preparing a 100-micron-sized self-doped spherical porous carbon material, comprising the following steps: carbonizing a 100-micron-sized spherical chitosan precursor to obtain the 100-micron-sized self-doped spherical porous carbon material. This invention utilizes 100-micron-sized spherical chitosan as a precursor, without using additional template agents or activators, and utilizes chitosan itself to provide the nitrogen source, obtaining the 100-micron-sized self-doped spherical porous carbon material through carbonization. Example results show that the 100-micron-sized self-doped spherical porous carbon material prepared by this invention contains 1-4 at% nitrogen element, according to... Figure 3 The results show that it contains pyridine N, graphitic N, and N oxide. The 100-micron-sized self-doped spherical porous carbon material is a black, metallic-luster spherical material with a single-particle crushing strength of 1.78–3.13 N and a specific surface area of 269–2100 m². 2 / g, with an average pore size of 2–4 nm; micropore size of 0.6–0.8 nm, and particle size of 100–600 μm.
[0019] As a preferred embodiment, the present invention utilizes suspension polymerization to prepare a large quantity of highly cross-linked, spherical chitosan precursors with a particle size of hundreds of micrometers, thereby improving reagent utilization efficiency, avoiding the use of more reagents, especially toxic reagents, and making the precursor preparation process more environmentally friendly.
[0020] As a preferred embodiment, the present invention adjusts and optimizes the carbonization process according to the properties of the precursor to achieve the preparation of spherical porous carbon materials with both high specific surface area and N content, reduce energy consumption in the carbonization process, reduce waste generation, and is more suitable for large-scale production. Attached Figure Description
[0021] Figure 1 An optical microscope image of the 100-micrometer-scale self-doped spherical porous carbon material C-1 prepared in Example 1;
[0022] Figure 2 SEM image of the 100-micron-sized self-doped spherical porous carbon material C-1 prepared in Example 1;
[0023] Figure 3 XPS spectrum of N1s orbital of C-1, a 100-micron-sized self-doped spherical porous carbon material prepared in Example 1;
[0024] Figure 4 The XRD pattern of the 100-micron-sized self-doped spherical porous carbon material C-1 prepared in Example 1 is shown below.
[0025] Figure 5 The pore distribution curve of the 100-micron-sized self-doped spherical porous carbon material C-1 prepared in Example 1 is shown.
[0026] Figure 6The N2 adsorption-desorption curves of the 100-micron-sized self-doped spherical porous carbon material C-1 prepared in Example 1 are shown.
[0027] Figure 7 The image shows the XRD pattern of SC-1, a 100-micron-sized spherical chitosan precursor prepared in Example 1. Detailed Implementation
[0028] This invention provides a method for preparing self-doped spherical porous carbon materials at the hundred-micron scale, comprising the following steps:
[0029] Carbonization of 100-micron-sized spherical chitosan precursors yields 100-micron-sized self-doped spherical porous carbon materials.
[0030] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.
[0031] In this invention, the preferred method for preparing the 100-micron-sized spherical chitosan precursor includes:
[0032] Chitosan was dissolved in an aqueous acetic acid solution to obtain a dispersed phase; butyl acetate and Span 80 were mixed to obtain a continuous phase.
[0033] The dispersed phase and the continuous phase are mixed and suspended to obtain droplets of hundreds of micrometers in size; NaOH solution is added to carry out a precipitation reaction to obtain spherical chitosan precursors of hundreds of micrometers in size.
[0034] In this invention, chitosan is preferably dissolved in an aqueous acetic acid solution to obtain a dispersed phase. In this invention, the degree of deacetylation of the chitosan is preferably 75-95%, more preferably 85-90%. In this invention, the concentration of acetic acid in the dispersed phase is preferably 1-6 wt%, more preferably 3-4 wt%; the concentration of chitosan in the dispersed phase is preferably 3-6 wt%, more preferably 4-5 wt%.
[0035] In this invention, butyl acetate and Span 80 are mixed to obtain a continuous phase. In this invention, the volume ratio of butyl acetate to Span 80 is preferably 1:0.005–0.1, more preferably 1:0.02–0.05.
[0036] After obtaining the dispersed phase and the continuous phase, the present invention preferably mixes the dispersed phase and the continuous phase, and performs suspension dispersion to obtain droplets of hundreds of micrometers in size; then, NaOH solution is added to perform a precipitation reaction to obtain spherical chitosan precursors of hundreds of micrometers in size. In the present invention, the volume ratio of the dispersed phase to the continuous phase is preferably 1:2 to 4, more preferably 1:3 to 3.5. In the present invention, the mixing of the dispersed phase and the continuous phase preferably includes adding the dispersed phase to the continuous phase.
[0037] In this invention, the suspension dispersion is preferably carried out under stirring conditions; the stirring speed is preferably 100-500 r / min, more preferably 250-300 r / min; the suspension dispersion temperature is preferably 10-40℃, more preferably 25-30℃.
[0038] In this invention, the particle size of the hundred-micron-sized droplets is preferably 400–600 μm. The concentration of the NaOH solution is preferably 20–50 wt%, more preferably 40–50 wt%; the ratio of NaOH solution to chitosan is preferably 4–50 mL:5 g, more preferably 8–20 mL:5 g. This invention, by adding NaOH solution, gradually transforms the beads from transparent, viscous droplets into turbid gel beads.
[0039] In this invention, the precipitation reaction time is preferably 1–10 h, more preferably 4–8 h; the precipitation reaction temperature is preferably 10–40 °C, more preferably 20–30 °C. This invention, through the precipitation reaction, endows the beads with a certain strength, preventing significant shape changes under light compression. This invention utilizes the precipitation reaction to slow down the molecular chain stacking rate, resulting in spherical chitosan with high crystallinity and uniform crystalline region distribution.
[0040] Preferably, after the precipitation reaction, the obtained spherical chitosan is washed to obtain a 100-micron-sized spherical chitosan precursor. In this invention, the washing is preferably done with water, more preferably by immersion in deionized water. Preferably, the washing continues until the filtrate is neutral.
[0041] In this invention, the particle size of the 100-micron-sized spherical chitosan precursor is 400–600 μm. In this invention, the crystallinity of the 100-micron-sized spherical chitosan precursor is preferably 37–52%, and the average crystal region size is preferably… The 100-micron-sized spherical chitosan precursor prepared by this invention has a uniform structure, a 100-micron-sized particle size, and high cross-linking. This invention controls the crystallization of the 100-micron-sized spherical chitosan precursor, resulting in N-doped spherical carbon with a high specific surface area after carbonization. In this invention, the precursor with high crystallinity and small crystal region size exhibits intact spherical shape, large particle size, and high strength after carbonization.
[0042] After obtaining the 100-micron-sized spherical chitosan precursor, this invention carbonizes the 100-micron-sized spherical chitosan precursor to obtain a 100-micron-sized self-doped spherical porous carbon material. In this invention, the carbonization conditions preferably include: a first heating to 200–500°C under a protective atmosphere, followed by a first holding for 1–5 hours; a second heating to 600–1000°C, followed by a second holding for 2–5 hours; and natural cooling to room temperature. In this invention, the carbonization conditions more preferably include: a first heating to 410–450°C under a protective atmosphere, followed by a first holding for 2–4 hours; a second heating to 660–900°C, followed by a second holding for 2–3 hours; and natural cooling to room temperature. In this invention, the heating rate of the first heating is preferably 3–10°C / min, more preferably 6–8°C / min; the heating rate of the second heating is preferably 3–10°C / min, more preferably 6–8°C / min. In this invention, the carbonization is preferably carried out in a quartz boat within a tube furnace. In this invention, the first heat preservation, the second heat preservation, and natural cooling are preferably all carried out under a protective atmosphere. Preferably, the protective atmosphere is a nitrogen atmosphere. The carbonization conditions described above are beneficial for increasing the specific surface area of carbon materials.
[0043] In this invention, the particle size of the self-doped spherical porous carbon material at the hundred-micron scale is preferably 100–600 μm, more preferably 300–400 μm; the specific surface area is preferably 269–2100 m². 2 / g, more preferably 1000-1772m 2 / g; the micropore size is preferably 0.6-0.8 nm; the average pore size is preferably 2-4 nm; the N content of the 100-micron-sized self-doped spherical porous carbon material is preferably 1-4 at%, more preferably 1.90-2.56 at%; the single-particle crushing strength of the 100-micron-sized self-doped spherical porous carbon material is preferably 1.78-3.13 N, more preferably 2.52-3.12 N. In this invention, the 100-micron-sized self-doped spherical porous carbon material has a black, metallic luster and is spherical in shape.
[0044] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0045] Example 1
[0046] 5 g of chitosan powder with a degree of deacetylation of 75% was dissolved in 120 mL of 4 wt% acetic acid aqueous solution to serve as the dispersed phase in suspension polymerization. This was then transferred to 480 mL of a continuous phase, which was a solution of butyl acetate containing 5 wt% Span 80. Using a top-mounted stirrer, spherical droplets were obtained under shear force (250 r / min, 25℃). Once the droplet size was uniform and stable at 400–600 μm, 12 mL of 50 wt% NaOH solution was added. The droplets gradually transformed from transparent, viscous droplets into turbid gel beads. After 4 hours of reaction, the chitosan beads exhibited a certain strength and did not show significant shape changes under slight compression. Stirring was then stopped. The spherical chitosan was then washed with a large amount of deionized water until neutral, yielding 100-micron-sized spherical chitosan precursor SC-1.
[0047] The 100-micron-sized spherical chitosan precursor SC-1 obtained above was transferred to a quartz boat and placed in a tube furnace. Under N2 atmosphere protection, the temperature was increased to 410°C at a heating rate of 6°C / min and held at this temperature for 2 hours. Then, the temperature was increased to 900°C at a heating rate of 6°C / min and held at this temperature for 2 hours. The material was then allowed to cool naturally to room temperature under N2 atmosphere and removed to obtain 100-micron-sized self-doped spherical porous carbon material C-1.
[0048] Figure 1 An optical microscope image of the 100-micrometer-scale self-doped spherical porous carbon material C-1 prepared in Example 1 shows the appearance and particle size of the spherical carbon. Figure 2 The image shows the SEM image of the 100-micron-sized self-doped spherical porous carbon material C-1 prepared in Example 1, which shows the appearance, particle size and surface structure of the spherical carbon. Figure 3 The XPS spectrum of the N1s orbital of the self-doped spherical porous carbon material C-1 prepared in Example 1 shows the N content and chemical state of the spherical carbon, which contains pyridine N, graphitic N, and N oxide. Figure 4 The XRD pattern of the self-doped spherical porous carbon material C-1 with a diameter of hundreds of micrometers prepared in Example 1 shows that the crystal structure of the spherical carbon is composed of a graphite phase. Figure 5 The pore distribution curve of the 100-micron-sized self-doped spherical porous carbon material C-1 prepared in Example 1 shows the pore size distribution of the spherical carbon. Figure 6 The N2 adsorption-desorption curves of the 100-micron-sized self-doped spherical porous carbon material C-1 prepared in Example 1 show the specific surface area of the spherical carbon. Figure 7 The XRD pattern of the 100-micron-sized spherical chitosan precursor SC-1 prepared in Example 1 provides information on the crystal structure of the precursor.
[0049] The 100-micron-sized spherical chitosan precursor SC-1 obtained in this embodiment, as analyzed by XRD, has a crystallinity of 45% and an average crystal region size of [missing information].
[0050] The self-doped spherical porous carbon material C-1 obtained in this embodiment has a black, metallic luster, spherical appearance, a particle size of 300–500 μm, an N content of 2.27 at%, a single-particle crushing strength of 3.12 N, and a specific surface area of 1439 m². 2 / g, with a micropore size of 0.8nm.
[0051] Example 2
[0052] 5 g of chitosan powder with a degree of deacetylation of 95% was dissolved in 120 mL of 4 wt% acetic acid aqueous solution to serve as the dispersed phase in suspension polymerization. This was then transferred to 480 mL of a continuous phase, which was a solution of butyl acetate containing 5 wt% Span 80. Using a top-mounted stirrer, spherical droplets were obtained under shear force (250 r / min, 25℃). Once the droplet size was uniform and stable at 400–600 μm, 12 mL of 50 wt% NaOH solution was added. The droplets gradually transformed from transparent, viscous droplets into turbid gel beads. After 4 hours of reaction, the chitosan beads exhibited a certain strength and did not show significant shape changes under slight compression. Stirring was then stopped. The spherical chitosan was washed with a large amount of deionized water until neutral, yielding 100-micron-sized spherical chitosan precursor SC-2.
[0053] The 100-micron-sized spherical chitosan precursor SC-2 obtained above was transferred to a quartz boat and placed in a tube furnace. Under N2 atmosphere protection, the temperature was increased to 410°C at a heating rate of 6°C / min and held at this temperature for 2 hours. Then, the temperature was increased to 900°C at a heating rate of 6°C / min and held at this temperature for 2 hours. The material was then allowed to cool naturally to room temperature under N2 atmosphere and removed to obtain 100-micron-sized self-doped spherical porous carbon material C-2.
[0054] The 100-micron-sized spherical chitosan precursor SC-2 obtained in this embodiment, as analyzed by XRD, has a crystallinity of 52% and an average crystal region size of [missing information].
[0055] The self-doped spherical porous carbon material C-2 obtained in this embodiment appears as black, metallic-lustered, flaky particles with a particle size of 200–400 μm, an N content of 2.56 at%, a single-particle crushing strength of 3.01 N, and a specific surface area of 2076 m². 2 / g, with a micropore size of 0.6nm.
[0056] Example 3
[0057] The 100-micron-sized spherical chitosan precursor SC-1 obtained in Example 1 was transferred to a quartz boat and placed in a tube furnace. Under N2 atmosphere protection, the temperature was increased to 410°C at a heating rate of 6°C / min and held at this temperature for 2 hours. Then, the temperature was increased to 660°C at a heating rate of 6°C / min and held at this temperature for 3 hours. The material was then allowed to cool naturally to room temperature under N2 atmosphere and removed to obtain 100-micron-sized self-doped spherical porous carbon material C-3.
[0058] The self-doped spherical porous carbon material C-3 obtained in this embodiment has a black, metallic luster and is preferably spherical with a particle size of 300–500 μm. It has an N content of 1.90 at%, a single-particle crushing strength of 3.07 N, and a specific surface area of 269 m². 2 / g, with a micropore size of 0.8nm.
[0059] Example 4
[0060] The 100-micron-sized spherical chitosan precursor SC-1 obtained in Example 1 was transferred to a quartz boat and placed in a tube furnace. Under N2 atmosphere protection, the temperature was increased to 410°C at a heating rate of 6°C / min and held at this temperature for 2 hours. Then, the temperature was increased to 900°C at a heating rate of 8°C / min and held at this temperature for 3 hours. The material was then allowed to cool naturally to room temperature under N2 atmosphere and removed to obtain 100-micron-sized self-doped spherical porous carbon material C-4.
[0061] The self-doped spherical porous carbon material C-4 obtained in this embodiment has a grayish-black, metallic luster, spherical appearance, a particle size of 200–400 μm, an N content of 2.02 at%, a single-particle crushing strength of 2.87 N, and a specific surface area of 1515 m². 2 / g, with a micropore size of 0.7nm.
[0062] Example 5
[0063] 5 g of chitosan powder with a degree of deacetylation of 85% was dissolved in 120 mL of 4 wt% acetic acid aqueous solution to serve as the dispersed phase in suspension polymerization. This was then transferred to 480 mL of a continuous phase, which was a solution of butyl acetate containing 5 wt% Span 80. Using a top-mounted stirrer, spherical droplets were obtained under shear force (250 r / min, 25℃). Once the droplet size was uniform and stable at 400–600 μm, 12 mL of 50 wt% NaOH solution was added. The droplets gradually transformed from transparent, viscous droplets into turbid gel beads. After 4 hours of reaction, the chitosan beads exhibited a certain strength and did not show significant shape changes under slight compression. Stirring was then stopped. The spherical chitosan was washed with a large amount of deionized water until neutral, yielding 100-micron-sized spherical chitosan precursor SC-5.
[0064] The 100-micron-sized spherical chitosan precursor SC-5 obtained above was transferred to a quartz boat and placed in a tube furnace. Under N2 atmosphere protection, the temperature was increased to 410°C at a heating rate of 6°C / min and held at this temperature for 2 hours. Then, the temperature was increased to 900°C at a heating rate of 6°C / min and held at this temperature for 2 hours. The material was then allowed to cool naturally to room temperature under N2 atmosphere and removed to obtain 100-micron-sized self-doped spherical porous carbon material C-5.
[0065] The 100-micron-sized spherical chitosan precursor SC-5 obtained in this embodiment, as analyzed by XRD, has a crystallinity of 46% and an average crystal region size of [missing information].
[0066] The self-doped spherical porous carbon material C-5 obtained in this embodiment appears as black, irregular particles with a particle size of 200–400 μm, an N content of 2.31 at%, a single-particle crushing strength of 2.98 N, and a specific surface area of 1772 m². 2 / g, with a micropore size of 0.7nm.
[0067] Example 6
[0068] 5 g of chitosan powder with a degree of deacetylation of 75% was dissolved in 120 mL of 3 wt% acetic acid aqueous solution to serve as the dispersed phase in suspension polymerization. This was then transferred to 480 mL of a continuous phase, which was a solution of butyl acetate containing 5 wt% Span 80. Using a top-mounted stirrer, spherical droplets were obtained under shear force (250 r / min, 25℃). Once the droplet size was uniform and stable at 400–600 μm, 12 mL of 50 wt% NaOH solution was added. The droplets gradually transformed from transparent, viscous droplets into turbid gel beads. After 1 hour of reaction, stirring was stopped. The spherical chitosan was washed with a large amount of deionized water until neutral, yielding 100-micron-sized spherical chitosan precursor SC-6.
[0069] The 100-micron-sized spherical chitosan precursor SC-6 obtained above was transferred to a quartz boat and placed in a tube furnace. Under N2 atmosphere protection, the temperature was increased to 410°C at a heating rate of 6°C / min and held at this temperature for 2 hours. Then, the temperature was increased to 900°C at a heating rate of 6°C / min and held at this temperature for 2 hours. The material was then allowed to cool naturally to room temperature under N2 atmosphere and removed to obtain 100-micron-sized self-doped spherical porous carbon material C-6.
[0070] The 100-micron-sized spherical chitosan precursor SC-6 obtained in this embodiment, as analyzed by XRD, has a crystallinity of 37% and an average crystal region size of [missing information].
[0071] The self-doped spherical porous carbon material C-6 obtained in this embodiment appears as black, flaky particles with a particle size of 100–300 μm, an N content of 2.30 at%, a single-particle crushing strength of 2.05 N, and a specific surface area of 1602 m². 2 / g, with a micropore size of 0.7nm.
[0072] Example 7
[0073] 5 g of chitosan powder with a degree of deacetylation of 75% was dissolved in 100 mL of 3 wt% acetic acid aqueous solution to serve as the dispersed phase in suspension polymerization. This was then transferred to 480 mL of a continuous phase containing 5 wt% butyl acetate (Span 80). Using a top-mounted stirrer, spherical droplets were obtained under shear force (250 r / min, 25℃). Once the droplet size was uniform and stable at 400–600 μm, 18 mL of 50 wt% NaOH solution was added. The droplets gradually transformed from transparent, viscous droplets into turbid gel beads. Stirring was stopped after 1 hour of reaction. The spherical chitosan was washed with a large amount of deionized water until neutral, yielding 100-micron-sized spherical chitosan precursor SC-7.
[0074] The 100-micron-sized spherical chitosan precursor SC-7 obtained above was transferred to a quartz boat and placed in a tube furnace. Under N2 atmosphere protection, the temperature was increased to 410°C at a heating rate of 6°C / min and held at this temperature for 2 hours. Then, the temperature was increased to 900°C at a heating rate of 6°C / min and held at this temperature for 2 hours. The material was then allowed to cool naturally to room temperature under N2 atmosphere and removed to obtain 100-micron-sized self-doped spherical porous carbon material C-7.
[0075] The 100-micron-sized spherical chitosan precursor SC-7 obtained in this embodiment, as analyzed by XRD, has a crystallinity of 40% and an average crystal region size of [missing information].
[0076] The self-doped spherical porous carbon material C-7 obtained in this embodiment appears as black ellipsoidal particles with a particle size of 100–600 μm, an N content of 2.20 at%, a single particle crushing strength of 1.78 N, and a specific surface area of 1202 m². 2 / g, with a micropore size of 0.7nm.
[0077] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a self-doped spherical porous carbon material at the hundred-micrometer scale, comprising the following steps: Carbonization of 100-micron-sized spherical chitosan precursors yields 100-micron-sized self-doped spherical porous carbon materials. The carbonization conditions include: first heating to 200~500℃ under a protective atmosphere, holding at that temperature for 1~5 hours; second heating to 600~1000℃, holding at that temperature for 2~5 hours; and then naturally cooling to room temperature. The particle size of the micron-level self-doped spherical porous carbon material is 100-600 mu m; the specific surface area is 269-2100 m 2 / g; the average pore size is 2-4 nm; the micropore size is 0.6-0.8 nm; The preparation method of the hundred-micron-sized spherical chitosan precursor includes: Chitosan was dissolved in an aqueous acetic acid solution to obtain a dispersed phase; butyl acetate and Span 80 were mixed to obtain a continuous phase. The dispersed phase and the continuous phase are mixed and suspended to obtain droplets of hundreds of micrometers in size; NaOH solution is added to carry out a precipitation reaction to obtain spherical chitosan precursors of hundreds of micrometers in size. The suspension dispersion is carried out under stirring conditions; the stirring speed is 100~500 r / min; the suspension dispersion temperature is 10~40℃. The volume ratio of the dispersed phase to the continuous phase is 1:2~4; The particle size of the 100-micron-sized spherical chitosan precursor is 400~600μm; the crystallinity of the 100-micron-sized spherical chitosan precursor is 37~52%, and the average crystal region size is 24~46Å.
2. The production method according to claim 1, characterized by, The degree of deacetylation of the chitosan is 75-95%.
3. The preparation method according to claim 1, characterized in that, The heating rate of the first heating is 3~10℃ / min; the heating rate of the second heating is 3~10℃ / min.
4. The method of claim 1, wherein, The N content of the self-doped spherical porous carbon material at the hundred-micrometer scale is 1~4 at.
5. The preparation method according to claim 1, characterized in that, The single-particle crushing strength of the self-doped spherical porous carbon material at the hundred-micrometer scale is 1.78~3.13N.