A bio-based three-dimensional multi-level porous carbon material and a preparation method and application thereof

Abstract

The present application relates to the field of preparation of bio-based multi-level pore carbon material and environmental governance, in particular to a kind of bio-based three-dimensional multi-level pore carbon material and its preparation method and application.The preparation method of bio-based three-dimensional multi-level pore carbon material of the present application includes the following steps: biomass raw material and phenol, composite acid catalyst are mixed and reacted 1, to obtain bio-based liquefied material;Bio-based liquefied material is mixed with composite base catalyst and polyformaldehyde, and then reacted 2, to obtain bio-based liquefied resin;Bio-based liquefied resin is mixed with surfactant, foaming agent, metal-based DES and curing agent, and then foamed, to obtain carbonization precursor;The carbonization precursor is subjected to carbonization treatment, and then ultrasonic water washing is carried out, to obtain bio-based three-dimensional multi-level pore carbon material.The bio-based three-dimensional multi-level pore carbon material prepared by the method of the present application has uniform structure, contains micron-nanometer multi-level pore structure, and has high adsorption performance.

Description

Technical Field

[0001] This invention relates to the field of bio-based hierarchical porous carbon material preparation and environmental remediation, and in particular to a bio-based three-dimensional hierarchical porous carbon material, its preparation method and application. Background Technology

[0002] Porous carbon materials, with their high specific surface area, well-developed pore structure, excellent surface chemistry, and good adsorption kinetics, have shown broad application potential in fields such as pollutant removal, gas storage, energy storage, and catalysis. However, the preparation of traditional porous carbon mainly relies on fossil resources such as coal, petroleum coke, and phenolic resins. These raw materials are not only limited in source and expensive, but their preparation process is also accompanied by high energy consumption and environmental pollution, making it difficult to meet the current needs of green and low-carbon development.

[0003] Biomass, due to its abundant carbon source and renewability, is considered an ideal precursor for char materials. However, biomass pyrolysis is a typical solid-phase carbonization process, and the morphology and pore structure of the resulting char material are limited by the inherent structure of the raw material, making it difficult to achieve precise control over the ordered pore structure, thus affecting the directional design and final performance of the material. Furthermore, traditional activation methods target solid carbon sources and use solid or liquid activators. While this can optimize the pore structure to some extent, solid-solid and solid-liquid mixtures may suffer from uneven activation, pore structure collapse, and uneven pore size distribution, limiting further applications. Therefore, how to construct high-performance hierarchical porous char materials with uniform and precisely controllable pore structures based on woody biomass has become a key technical challenge that urgently needs to be addressed in bio-based char materials. Summary of the Invention

[0004] In view of this, the present invention provides a bio-based three-dimensional hierarchical porous carbon material, its preparation method, and its application. The present invention uses biomass as raw material and employs techniques such as catalytic liquefaction, molecular reconstruction, physical foaming, and gas-phase carbonization to prepare a bio-based three-dimensional hierarchical porous carbon material with uniform structure, containing micron- and nano-level hierarchical pores, and possessing highly efficient adsorption properties.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] One of the technical solutions of this invention is a method for preparing a bio-based three-dimensional hierarchical porous carbon material, comprising the following steps:

[0007] Step 1: Mix biomass raw materials with phenol and composite acid catalyst to carry out reaction 1 to obtain bio-based liquefaction;

[0008] Step 2: The bio-based liquefied material is mixed with the composite alkali catalyst and paraformaldehyde and then reacted to obtain the bio-based liquefied resin.

[0009] Step 3: Mix the bio-based liquefied resin with surfactant, foaming agent, metal-based DES and curing agent and foam to obtain carbonized precursor.

[0010] Step 4: Carbonize the carbonization precursor and then ultrasonically wash it with water to obtain the bio-based three-dimensional hierarchical porous carbon material.

[0011] In step 1, the composite acid catalyst is a mixture of a strong acid and acidic DES.

[0012] The second technical solution of the present invention is a bio-based three-dimensional hierarchical porous carbon material prepared according to the above preparation method.

[0013] The third technical solution of the present invention is an adsorption material, the raw material of which includes the above-mentioned bio-based three-dimensional hierarchical porous carbon material.

[0014] The present invention discloses the following technical effects:

[0015] 1. This application innovatively selects a green acidic eutectic solvent (DES) and a strong acid as a co-catalytic system. This system not only efficiently promotes the separation and degradation of the three major components of biomass (cellulose, hemicellulose, and lignin), but also significantly improves the reactivity of small molecule compounds in the degradation products, thereby enhancing liquefaction efficiency and reducing residue rate. The liquefaction product (bio-based liquefaction) is a phenolic compound formed by the reaction of phenol with the small molecules of the three major components. Without further purification, it can directly undergo a condensation reaction with paraformaldehyde to generate bio-based phenolic resin. The cellulose degradation product possesses good toughening properties, effectively improving the brittleness problem of traditional phenolic foam materials. Furthermore, the insoluble substances remaining during the liquefaction process can act as heterogeneous nucleating agents in the subsequent foaming reaction, further promoting the uniform formation of the cell structure.

[0016] 2. This application uses paraformaldehyde instead of traditional formaldehyde solution to synthesize liquefied resin, combined with a one-pot synthesis process, resulting in a bio-based liquefied resin with high solids content, low viscosity, and rapid low-temperature curing characteristics. This process is green and environmentally friendly, producing no waste liquid or byproducts, simplifying post-processing, significantly improving process efficiency, reducing production energy consumption, and enhancing the product's economic viability and environmental sustainability.

[0017] 3. This application overcomes the technical limitations of traditional activation methods applied to solid precursors by employing liquefaction technology to transform the carbonization precursor from a solid to a liquid state, and introduces metal-based DES to participate in foaming activation. This strategy significantly improves the dispersibility and activity of the activator in the system, enhancing the efficiency of microstructure regulation. The metal-based DES used (a blend of choline chloride and metal chloride salt) can serve as a dual catalyst for resin curing and carbonization during the carbonization process, and can also precisely construct nanoscale pore structures through the metal salt template effect, achieving synergistic regulation of micron and nanoscale pore sizes.

[0018] 4. This application employs foaming technology to construct a three-dimensional carbonization precursor with a thin-walled pore structure. The interconnected pores in this precursor facilitate gas flow and effectively improve the uniformity and completeness of the carbonization reaction. Furthermore, it avoids excessively high local gas pressure caused by temperature rise, which could lead to structural collapse, thus ensuring the stability of the three-dimensional framework structure at high temperatures. Simultaneously, through a triple regulation strategy of "high-temperature carbonization (primary regulation) + catalytic activation (secondary regulation) + ultrasonic water washing (tertiary regulation)," precise adjustment of the pore size structure is achieved, significantly improving the specific surface area and pore diversity of the material, thereby enhancing the comprehensive performance of the prepared porous carbon material in adsorption and other applications. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a scanning electron microscope image of the internal pore structure of the bio-based three-dimensional hierarchical porous carbon material prepared in Example 4.

[0021] Figure 2 This is a digital photograph of the bio-based three-dimensional hierarchical porous carbon material prepared in Example 4. Detailed Implementation

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0025] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0026] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0027] This invention presents a novel technical approach that enables the synergistic control of micron- and nano-scale pores in three-dimensional porous carbon, resulting in excellent pore structure and adsorption performance.

[0028] The first aspect of this invention provides a method for preparing a bio-based three-dimensional hierarchical porous carbon material, comprising the following steps:

[0029] Step 1: Mix biomass raw materials with phenol and composite acid catalyst to carry out reaction 1 to obtain bio-based liquefaction;

[0030] Step 2: The bio-based liquefied material is mixed with the composite alkali catalyst and paraformaldehyde and then reacted to obtain the bio-based liquefied resin.

[0031] Step 3: Mix the bio-based liquefied resin with surfactant, foaming agent, metal-based DES and curing agent and foam to obtain carbonized precursor.

[0032] Step 4: Carbonize the carbonization precursor and then ultrasonically wash it with water to obtain the bio-based three-dimensional hierarchical porous carbon material.

[0033] In step 1, the composite acid catalyst is a mixture of a strong acid and acidic DES.

[0034] In a preferred embodiment of the present invention, in step 1, the mass ratio of the biomass raw material to the phenol and the composite acid catalyst is 1:(2~3):0.2; the strong acid is hydrochloric acid and / or sulfuric acid; the acidic DES is a mixture of choline chloride and oxalic acid in a molar ratio of 1:1, and / or a mixture of choline chloride and phosphoric acid in a molar ratio of 1:1; the biomass raw material is at least one of poplar wood powder, peanut shell powder, walnut shell powder, and camellia shell powder.

[0035] In this invention, the acidic DES is specified as a mixture of choline chloride and oxalic acid in a 1:1 molar ratio, and / or a mixture of choline chloride and phosphate in a 1:1 molar ratio, because the 1:1 ratio ensures the presence of acidic protons (H). + ) and choline hydrogen bond receptors (Cl - The system achieves stoichiometric equilibrium by adding choline chloride (or -OH) to provide moderate acidity and proton conductivity. Excess choline chloride weakens the acidity of the system, reducing the catalytic activity of DES. Insufficient choline chloride results in an incomplete hydrogen bond network, making it difficult for the system to form a stable liquid phase, leading to crystallization and phase separation.

[0036] In a preferred embodiment of the present invention, in step 1, the reaction temperature of reaction 1 is 120~150℃ and the reaction time is 60~100min; after reaction 1 is completed, the reaction system is further further adjusted to neutral pH using an alkaline solution and cooled to 30~40℃.

[0037] In a preferred embodiment of the present invention, in step 2, the mass ratio of the bio-based liquefied material to the composite base catalyst and paraformaldehyde is 1:(0.08~0.12):(0.3~0.5); the composite base catalyst is a mixture of 40wt% sodium hydroxide solution and zinc hydroxide in a mass ratio of 4:1; the reaction temperature of reaction 2 is 75~90℃, and the reaction time is 30~60min; after reaction 2 is completed, the reaction further includes a step of cooling to below 40℃ and then adjusting the pH of the reaction system to neutral with dilute hydrochloric acid.

[0038] The solid content of the bio-based liquefied resin is 65%~70%.

[0039] In a preferred embodiment of the present invention, in step 3, the mass ratio of the bio-based liquefied resin to the surfactant, foaming agent, metal-based DES, and curing agent is 1:(0.05-0.1):(0.04-0.08):(0.1-0.3):(0.05-0.1); the surfactant is a nonionic surfactant; the foaming agent is an alkane with a boiling point less than 70°C, such as n-pentane and / or n-hexane; the metal-based DES is a mixture of choline chloride and ferric chloride in a molar ratio of 1:2, and / or a mixture of choline chloride and zinc chloride in a molar ratio of 1:2; the curing agent is a mixture of a strong acid and a weak acid in a mass ratio of 3:1.

[0040] In this invention, the reason for limiting the metal-based DES to a mixture of choline chloride and ferric chloride in a molar ratio of 1:2, and / or a mixture of choline chloride and zinc chloride in a molar ratio of 1:2 is that 1:2 is the thermodynamically optimal ratio for metal-based DES. Exceeding this ratio will result in an incompletely homogeneous mixture.

[0041] In this invention, the curing agent is limited to a mixture of strong acid and weak acid in a mass ratio of 3:1 because a curing agent with a mass ratio of strong acid to weak acid of 3:1 can ensure the curing rate. If there is too much strong acid, the curing will be too fast and foaming will not be possible; if there is too little strong acid, the foaming system will not have enough acidity and will not be able to cure.

[0042] In a preferred embodiment of the present invention, the nonionic surfactant is a Tween-type and / or castor oil polyoxyethylene ether surfactant; the strong acid is hydrochloric acid and / or p-toluenesulfonic acid; and the weak acid is at least one of formic acid, phosphoric acid, and sulfurous acid.

[0043] In a preferred embodiment of the present invention, in step 3, the foaming is specifically performed at 70~90℃ for 60~120 minutes.

[0044] In a preferred embodiment of the present invention, in step 4, the carbonization treatment specifically involves carbonizing at 800~1000℃ for 2~3 hours under an inert atmosphere; the ultrasonic water washing specifically involves ultrasonic water washing at 220W power until the pH of the product obtained from the carbonization treatment is stable.

[0045] A second aspect of the present invention provides a bio-based three-dimensional hierarchical porous carbon material prepared according to the above-described preparation method.

[0046] A third aspect of the present invention provides an adsorption material, the raw material of which includes the above-mentioned bio-based three-dimensional hierarchical porous carbon material.

[0047] This invention innovatively integrates key preparation steps such as liquefaction, resinification, foaming, carbonization, and activation into a unified continuous process. By systematically designing the morphology and structure of the precursors at each stage, it achieves efficient synergy and seamless connection between stages. No additional treatment is required for the resin composite or carbonized precursors throughout the process, effectively simplifying the process steps, improving preparation efficiency, and fully embodying the green and integrated material design concept.

[0048] To enhance the application performance of this porous carbon material, this invention employs a three-stage synergistic control strategy: high-temperature carbonization (primary regulation), catalytic activation (secondary regulation), and ultrasonic water washing (tertiary regulation), achieving controllable construction of its nanoscale pore structure. Due to its multi-scale pore structure, large specific surface area, abundant micropores, and tunable functional groups, this material exhibits excellent broad-spectrum adsorption performance in water pollutant treatment.

[0049] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0050] The main reagents / raw materials used and their sources in the embodiments and comparative examples of this invention are shown in Table 1:

[0051] Table 1. Reagents / Materials and Their Sources

[0052]

[0053] The composite alkaline catalyst used in the embodiments and comparative examples of this invention is a mixture of sodium hydroxide solution (40 wt% concentration, solvent: water) and zinc hydroxide in a mass ratio of 4:1. The technical solutions provided by this invention will be described in detail below with reference to the embodiments, but these should not be construed as limiting the scope of protection of this invention.

[0054] Example 1

[0055] A method for preparing a bio-based three-dimensional hierarchical porous carbon material, comprising the following steps:

[0056] (1) Mix peanut shell powder and phenol at a mass ratio of 1:2, then add a composite acid catalyst and mix well (the composite acid catalyst is a mixture of sulfuric acid, oxalic acid and choline chloride in a molar ratio of 3:1:1; the mass ratio of peanut shell powder to composite acid catalyst is 1:0.2). React at 140℃ for 80 min, then reduce the temperature to 30℃ and add NaOH solution to adjust the pH to neutral to obtain bio-based liquefaction.

[0057] (2) The bio-based liquefied material, composite alkali catalyst and paraformaldehyde were mixed evenly in a mass ratio of 1:0.08:0.4, heated to 75°C, reacted for 55 min, cooled to below 40°C, and the pH was adjusted to neutral with dilute hydrochloric acid to obtain a bio-based liquefied resin with a solid content of about 65%.

[0058] (3) A mixture of bio-based liquefied resin, castor oil polyoxyethylene ether, n-pentane, choline chloride and ferric chloride in a molar ratio of 1:2 and a mixed solution of hydrochloric acid and sulfurous acid in a mass ratio of 3:1 were mixed evenly in a mass ratio of 1:0.06:0.06:0.1:0.1 and foamed at 85°C for 60 min to obtain a carbonized precursor.

[0059] (4) The carbonization precursor was carbonized at 800℃ under nitrogen protection for 2.5h. The product was washed with ultrasonic water at 220W until the pH was stable to obtain bio-based three-dimensional hierarchical porous carbon material.

[0060] Example 2

[0061] A method for preparing a bio-based three-dimensional hierarchical porous carbon material, comprising the following steps:

[0062] (1) Mix camellia shell powder and phenol at a mass ratio of 1:3, then add a composite acid catalyst and mix well (the composite acid catalyst is a mixture of sulfuric acid, oxalic acid and choline chloride in a molar ratio of 3:1:1; the mass ratio of camellia shell powder to composite acid catalyst is 1:0.2). React at 130℃ for 100 min, then reduce the temperature to 30℃, add NaOH solution to adjust the pH to neutral, and obtain bio-based liquefaction.

[0063] (2) The bio-based liquefied material, composite alkali catalyst and paraformaldehyde were mixed evenly in a mass ratio of 1:0.11:0.35, heated to 85°C, reacted for 45 min, cooled to below 40°C, and the pH was adjusted to neutral with dilute hydrochloric acid to obtain a bio-based liquefied resin with a solid content of about 65%.

[0064] (3) A mixture of bio-based liquefied resin, Tween 80, n-hexane, choline chloride and ferric chloride in a molar ratio of 1:2 and a mixed solution of p-toluenesulfonic acid and sulfurous acid in a mass ratio of 3:1 were mixed evenly at a mass ratio of 1:0.09:0.04:0.12:0.08 and foamed at 70°C for 120 min to obtain a carbonized precursor.

[0065] (4) The carbonization precursor was carbonized at 900℃ under nitrogen protection for 2.5h. The product was washed with 220W ultrasonic water until the pH was stable to obtain bio-based three-dimensional hierarchical porous carbon material.

[0066] Example 3

[0067] A method for preparing a bio-based three-dimensional hierarchical porous carbon material, comprising the following steps:

[0068] (1) Mix walnut shell powder and phenol at a mass ratio of 1:2, then add a composite acid catalyst and mix well (the composite acid catalyst is a mixture of hydrochloric acid, phosphoric acid and choline chloride in a molar ratio of 6:1:1; the mass ratio of walnut shell powder to composite acid catalyst is 1:0.2). React at 120℃ for 90 min, then reduce the temperature to 30℃, add NaOH solution to adjust the pH to neutral, and obtain bio-based liquefaction.

[0069] (2) The bio-based liquefied material, composite alkali catalyst and paraformaldehyde were mixed evenly in a mass ratio of 1:0.1:0.45, heated to 90°C, reacted for 40 min, cooled to below 40°C, and the pH was adjusted to neutral with dilute hydrochloric acid to obtain a bio-based liquefied resin with a solid content of about 65%.

[0070] (3) A mixture of bio-based liquefied resin, castor oil polyoxyethylene ether, n-hexane, choline chloride and zinc chloride in a molar ratio of 1:2 and a mixed solution of p-toluenesulfonic acid and phosphoric acid in a mass ratio of 3:1 were mixed evenly in a mass ratio of 1:0.08:0.08:0.2:0.05 and foamed at 80°C for 60 min to obtain a carbonized precursor.

[0071] (4) The carbonization precursor was carbonized at 1000℃ under nitrogen protection for 2h. The product was washed with 220W ultrasonic water until the pH was stable to obtain bio-based three-dimensional hierarchical porous carbon material.

[0072] Example 4

[0073] A method for preparing a bio-based three-dimensional hierarchical porous carbon material, comprising the following steps:

[0074] (1) Mix poplar powder and phenol at a mass ratio of 1:3, then add a composite acid catalyst and mix well (the composite acid catalyst is a mixture of hydrochloric acid, phosphoric acid and choline chloride in a molar ratio of 6:1:1; the mass ratio of poplar powder to composite acid catalyst is 1:0.2). React at 130℃ for 60 min, add NaOH solution to adjust the pH to neutral, and lower the temperature to 30℃ to obtain bio-based liquefaction.

[0075] (2) The bio-based liquefied material, composite alkali catalyst and paraformaldehyde are mixed evenly in a mass ratio of 1:0.1:0.5, heated to 90°C, reacted for 30 min, cooled to below 40°C, and the pH was adjusted to neutral with dilute hydrochloric acid to obtain a bio-based liquefied resin with a solid content of about 65%.

[0076] (3) Mix bio-based liquefied resin, Tween 80, n-pentane, choline chloride and zinc chloride in a molar ratio of 1:2 and a mixed solution of hydrochloric acid and formic acid in a mass ratio of 3:1 in a mass ratio of 1:0.05:0.05:0.25:0.05, and foam at 75°C for 100 min to obtain a carbonized precursor.

[0077] (4) The carbonization precursor was carbonized at 1000℃ under nitrogen protection for 2h. The product was washed with 220W ultrasonic water until the pH was stable to obtain bio-based three-dimensional hierarchical porous carbon material.

[0078] Comparative Example 1

[0079] The only difference from Example 4 is that step (4) is omitted.

[0080] Comparative Example 2

[0081] The only difference from Example 4 is that the addition of the mixture of choline chloride and zinc chloride is omitted in step (3).

[0082] Comparative Example 3

[0083] The only difference from Example 4 is that the step of “washing the product with ultrasonic water until the pH is stable” is omitted in step (4).

[0084] Performance testing

[0085] Average pore diameter test at the micron level: Images were taken using a scanning electron microscope (SEM) and the diameter of the micron-level pores was measured.

[0086] Average pore size, specific surface area, and total pore volume of nanoscale pores were tested: N2 adsorption-desorption curves were determined using a specific surface area and pore structure analyzer (BET), and the average pore size, specific surface area, and total pore volume were calculated using the BET model and t-plot model.

[0087] Adsorption capacity tests for methylene blue and divalent copper ions: 30 mg of the bio-based three-dimensional hierarchical porous carbon materials prepared in Examples 1-4 and Comparative Examples 1-3 were respectively placed into 50 mL of water containing 1000 mg / L methylene blue and divalent copper ions. The mixtures were stirred at 25°C for 24 h to ensure adsorption equilibrium was reached. The formula for calculating the adsorption capacity of harmful substances is as follows:

[0088] Qe=(C0-Ce)V / m

[0089] In the formula:

[0090] Qe (mg / g): equilibrium adsorption capacity

[0091] C0 (mg / L): Initial concentration of methylene blue / divalent copper ion aqueous solution

[0092] Ce (mg / L): Equilibrium concentration of methylene blue / divalent copper ions in aqueous solution

[0093] m(g): mass of biochar.

[0094] Table 2 Performance Test Results

[0095]

[0096] The comparison between Example 4 and Comparative Examples 1, 2, and 3 in this application is based on the same raw materials and basic process conditions, with variable control only on key process steps, in order to verify the effectiveness and advantages of the core technical solution of the present invention: Comparative Example 1 did not undergo carbonization treatment (first-stage control); Comparative Example 2 did not add metal-based DES (second-stage control); Comparative Example 3 did not undergo ultrasonic treatment after carbonization (third-stage control).

[0097] As shown in Table 2, compared with the comparative examples above, the bio-based three-dimensional hierarchical porous carbon material prepared in Example 4 achieved significant improvements in both specific surface area and total pore volume. This indicates that the synergistic regulation mechanism of carbonization + activation + ultrasound plays a core role in the construction of porous structures: high-temperature carbonization (primary regulation) effectively promotes the volatilization and pyrolysis of non-carbon elements, forming microporous structures; chemical activation (secondary regulation) further promotes the carbonization process, and the volatilization and decomposition of metal compounds as templates under high-temperature conditions can create more microporous structures; while ultrasonic treatment (tertiary regulation) helps to release the template effect, expand pore connectivity and micropore exposure, thereby significantly improving the specific surface area and pore volume of the material.

[0098] Regarding adsorption performance, Example 4 showed positive results for methylene blue and Cu. 2+ The adsorption capacity is much higher than that of Comparative Example 1, and better than that of Comparative Examples 2 and 3, which verifies that the hierarchical porous carbon material prepared in this invention has excellent adsorption capacity for typical water pollutants.

[0099] This invention achieves precise control over the structure of three-dimensional hierarchical porous carbon materials through a synergistic process of resin liquefaction, foaming, activation, carbonization, and ultrasound, exhibiting superior performance in terms of specific surface area, pore volume, and adsorption capacity for organic pollutants. Its technical route is simple, scalable, and suitable for the industrial preparation of high-performance adsorption materials.

[0100] Figure 1 This is a scanning electron microscope image of the internal pore structure of the bio-based three-dimensional hierarchical porous carbon material prepared in Example 4. Figure 1 It can be seen that the basic framework structure of the material is a foam structure with interconnected bubble walls. The pore structure on the bubble walls is about 5 μm, which can give the material good air permeability and facilitate the transfer of adsorbate.

[0101] Figure 2 This is a digital photograph of the bio-based three-dimensional hierarchical porous carbon material prepared in Example 4. Figure 2 It can be seen that after high-temperature carbonization, the basic framework of the material remains stable and does not collapse, and it can still maintain a good three-dimensional structure, which is conducive to the recycling of the material.

[0102] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a bio-based three-dimensional hierarchical porous carbon material, characterized in that, Includes the following steps: Step 1: Mix biomass raw materials with phenol and composite acid catalyst to carry out reaction 1 to obtain bio-based liquefaction; Step 2: The bio-based liquefied material is mixed with the composite alkali catalyst and paraformaldehyde and then reacted to obtain the bio-based liquefied resin. Step 3: Mix the bio-based liquefied resin with surfactant, foaming agent, metal-based DES and curing agent and foam to obtain carbonized precursor. Step 4: Carbonize the carbonization precursor and then ultrasonically wash it with water to obtain the bio-based three-dimensional hierarchical porous carbon material. In step 1, the composite acid catalyst is a mixture of strong acid and acidic DES in a molar ratio of (3~6):

2.

2. The method for preparing bio-based three-dimensional hierarchical porous carbon material according to claim 1, characterized in that, In step 1, the mass ratio of the biomass raw material to the phenol and the composite acid catalyst is 1:(2~3):0.2; the strong acid is hydrochloric acid and / or sulfuric acid; the acidic DES is a mixture of choline chloride and oxalic acid in a molar ratio of 1:1, and / or a mixture of choline chloride and phosphoric acid in a molar ratio of 1:1; the biomass raw material is at least one of poplar wood powder, peanut shell powder, walnut shell powder, and camellia shell powder.

3. The method for preparing bio-based three-dimensional hierarchical porous carbon material according to claim 1, characterized in that, In step 1, the reaction temperature of reaction 1 is 120~150℃ and the reaction time is 60~100min; after reaction 1 is completed, the reaction system is further adjusted to neutral pH using an alkaline solution and cooled to 30~40℃.

4. The method for preparing bio-based three-dimensional hierarchical porous carbon material according to claim 1, characterized in that, In step 2, the mass ratio of the bio-based liquefied material to the composite base catalyst and paraformaldehyde is 1:(0.08~0.12):(0.3~0.5); the composite base catalyst is a mixture of 40wt% sodium hydroxide solution and zinc hydroxide in a mass ratio of 4:1; the reaction temperature of step 2 is 75~90℃, and the reaction time is 30~60min; after step 2, the reaction also includes a step of cooling to below 40℃ and then adjusting the pH of the reaction system to neutral with dilute hydrochloric acid.

5. The method for preparing bio-based three-dimensional hierarchical porous carbon material according to claim 1, characterized in that, In step 3, the mass ratio of the bio-based liquefied resin to the surfactant, foaming agent, metal-based DES, and curing agent is 1:(0.05-0.1):(0.04-0.08):(0.1-0.3):(0.05-0.1); the surfactant is a nonionic surfactant; the foaming agent is an alkane with a boiling point less than 70°C; the metal-based DES is a mixture of choline chloride and ferric chloride in a molar ratio of 1:2, and / or a mixture of choline chloride and zinc chloride in a molar ratio of 1:2; the curing agent is a mixture of a strong acid and a weak acid in a mass ratio of 3:

1.

6. The method for preparing bio-based three-dimensional hierarchical porous carbon material according to claim 5, characterized in that, The nonionic surfactant is a Tween-type and / or castor oil polyoxyethylene ether surfactant; the strong acid is hydrochloric acid and / or p-toluenesulfonic acid; the weak acid is at least one of formic acid, phosphoric acid, and sulfurous acid.

7. The method for preparing bio-based three-dimensional hierarchical porous carbon material according to claim 1, characterized in that, In step 3, the foaming process specifically involves foaming at 70-90℃ for 60-120 minutes.

8. The method for preparing bio-based three-dimensional hierarchical porous carbon material according to claim 1, characterized in that, In step 4, the carbonization treatment specifically involves carbonizing at 800~1000℃ for 2~3 hours under an inert atmosphere; the ultrasonic water washing specifically involves ultrasonic water washing at 220W power until the pH of the product obtained from the carbonization treatment is stable.

9. A bio-based three-dimensional hierarchical porous carbon material prepared by the preparation method according to any one of claims 1 to 8.

10. An adsorbent material, characterized in that, The raw materials include the bio-based three-dimensional hierarchical porous carbon material as described in claim 9.

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