Preparation method of biomass-based activated carbon
The preparation of biomass-based activated carbon by ash-flue gas synergistic activation method overcomes the shortcomings of traditional activation methods, realizes the preparation of porous carbon materials with high efficiency, low cost and environmental protection, and improves resource utilization.
Patent Information
- Application Number
- CN202511354156.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-22
- Publication Date
- 2025-11-18
AI Technical Summary
Existing physical activation and chemical activation methods each have their shortcomings in the preparation of activated carbon. Physical activation has limited pore structure, while chemical activation is costly and poses significant environmental risks.
A porous carbon material was prepared by using the ash-flue gas synergistic activation method, which utilizes the ash and flue gas after biomass combustion as activators and combines physical and chemical activation mechanisms.
Porous carbon materials with high specific surface area and rich pore structure were prepared, which reduced the dependence on external activators, reduced environmental pollution, improved resource utilization, and the process was simple and controllable.
Smart Images
Figure CN120964803A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of biomass energy utilization, and in particular to a method for preparing biomass-based activated carbon. Background Technology
[0002] Energy utilization and material development are two important ways of utilizing biomass, and it is of great significance to achieve the coupled utilization of these two methods.
[0003] Activated carbon is one of the most commonly used carbon materials in modern production and daily life. It possesses a high specific surface area and a well-developed pore structure, resulting in highly efficient adsorption capacity. It has wide applications in air purification, water treatment, food, and pharmaceuticals. Currently, commonly used activated carbon activation methods include physical activation and chemical activation. Physical activation typically relies on gases such as water vapor and CO2 to create pores in the carbon material. It has advantages such as relatively simple operation and minimal environmental impact, but the pore structure is limited. Chemical activation, on the other hand, creates pores through chemical etching, resulting in carbon materials with a larger specific surface area and a more developed pore structure. However, the cost of the activating agents is higher, and it also poses some environmental risks. Summary of the Invention
[0004] In view of this, in order to at least partially solve at least one of the aforementioned technical problems, this disclosure provides a method for preparing biomass-based activated carbon.
[0005] According to one embodiment of this disclosure, a method for preparing biomass-based activated carbon is provided, comprising: performing combustion treatment on biomass and collecting the ash and flue gas after combustion; performing pyrolysis treatment on biomass to obtain biochar; mixing biochar and ash to obtain a first mixture; adding flue gas to the first mixture to perform an activation reaction to obtain a second mixture; and performing acid washing, water washing and drying treatment on the second mixture to obtain biomass-based activated carbon.
[0006] According to embodiments of this disclosure, the mass ratio of biochar to ash is (0.5~10):1.
[0007] According to embodiments of this disclosure, the volume ratio of biochar to flue gas is (50~400):1.
[0008] According to embodiments of this disclosure, the biomass combustion process includes: burning the biomass under an oxygen-rich environment.
[0009] According to embodiments of this disclosure, pyrolysis of biomass includes: pyrolysis of biomass under anaerobic or anaerobic conditions.
[0010] According to embodiments of this disclosure, the pyrolysis temperature in the pyrolysis treatment is 400°C to 700°C.
[0011] According to embodiments of this disclosure, the pyrolysis temperature in the pyrolysis treatment is 550°C to 650°C.
[0012] According to embodiments of this disclosure, the activation temperature in the activation reaction is 500℃~1000℃, and the activation time is 0.25h~2h.
[0013] According to embodiments of this disclosure, the activation temperature in the activation reaction is 800℃~900℃, and the activation time is 0.5h~1h.
[0014] According to embodiments of this disclosure, before subjecting biomass to combustion or pyrolysis, the method further includes: pulverizing the biomass.
[0015] According to embodiments of this disclosure, a porous carbon material with high specific surface area and rich pore structure is successfully prepared by using the ash-flue gas synergistic activation method, which uses the ash and flue gas generated during biomass combustion as activators and combines physical and chemical activation mechanisms.
[0016] The embodiments disclosed herein fully utilize the ash and flue gas generated from biomass combustion as activators, replacing traditional expensive and toxic chemical reagents. This not only reduces dependence on external raw materials but also achieves resource integration throughout the entire biomass "combustion-pyrolysis-material conversion" process, embodying an integrated design concept of energy and materials utilization and improving overall resource utilization. Furthermore, it eliminates the need for highly corrosive or toxic chemical activators, effectively reducing the risk of chemical pollution to the environment. Simultaneously, the raw materials used are widely available and inexpensive, and the ash and flue gas are combustion byproducts, obtained at virtually zero cost, making the entire process simple and controllable. Attached Figure Description
[0017] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:
[0018] Figure 1 A flowchart illustrating a preparation method according to an embodiment of the present disclosure is shown schematically.
[0019] Figure 2 A scanning electron microscope image of biomass-based activated carbon according to Example 1 of this disclosure is shown schematically.
[0020] Figure 3 A scanning electron microscope image of biomass-based activated carbon according to Embodiment 11 of this disclosure is shown schematically.
[0021] Figure 4 A transmission electron microscope (TEM) image of biomass-based activated carbon according to Embodiment 11 of this disclosure is shown schematically. Detailed Implementation
[0022] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.
[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.
[0024] In this disclosure, the term "ash" refers to the inorganic matter remaining after the complete combustion of biomass, primarily composed of minerals, and typically includes metallic elements in oxide form, such as... , CaO, etc.
[0025] The term "flue gas" refers to the gases released during the combustion of biomass, mainly including CO, , wait.
[0026] Figure 1 A flowchart illustrating a preparation method according to an embodiment of the present disclosure is shown schematically.
[0027] like Figure 1 As shown, the method for preparing biomass-based activated carbon in this embodiment includes:
[0028] S1: The biomass is burned, and the ash and flue gas after combustion are collected.
[0029] S2: Biomass is pyrolyzed to obtain biochar.
[0030] S3: Mix biochar and ash to obtain the first mixture.
[0031] S4: Add flue gas to the first mixture to carry out an activation reaction and obtain the second mixture.
[0032] S5: The second mixture is subjected to acid washing, water washing and drying to obtain biomass-based activated carbon.
[0033] In the embodiments of this disclosure, ash and flue gas are used to modify biochar through chemical etching and physical activation, respectively, jointly promoting the preparation of porous carbon materials with high specific surface area and well-developed pore structure. This method not only effectively utilizes all products in the biomass conversion process but also reduces the need for external activators, reflecting the principle of efficient resource utilization. Specifically, in the preparation of porous carbon materials, ash... , CaO and other substances can act as chemical etching agents, helping to form microporous structures, thereby increasing the specific surface area and adsorption capacity of the final product. During the conversion of biomass into activated carbon, the flue gas contains... and It can be used as a physical activator to react with biochar under appropriate temperature conditions, helping to expand the pore structure, especially the formation of mesopores and macropores, and further optimize the pore distribution of porous carbon materials.
[0034] The preparation method described in this embodiment is simple, low-cost, and environmentally friendly. It utilizes biomass combustion byproducts as an activator, replacing traditional expensive and toxic chemical reagents. This not only reduces dependence on external raw materials but also achieves resource integration throughout the entire biomass "combustion-pyrolysis-material conversion" process, embodying an integrated design concept of energy and materials utilization and improving overall resource utilization. Furthermore, the raw materials used are widely available and inexpensive, with ash and flue gas being combustion byproducts, making them virtually cost-free. The entire process is simple and controllable, including steps such as combustion, pyrolysis, mixing, activation, acid washing, and drying. It is highly operable, easy to industrialize, and possesses good economic feasibility.
[0035] According to embodiments of this disclosure, the mass ratio of biochar to ash is (0.5~10):1.
[0036] According to embodiments of this disclosure, the volume ratio of biochar to flue gas is (50~400):1.
[0037] In embodiments of this disclosure, the ash is rich in... , Alkaline oxides such as CaO can promote the development of the microporous structure within biochar. By adjusting the ratio of biochar to ash, the degree of chemical etching can be precisely controlled, thereby optimizing the pore structure and specific surface area of the final product. (The last sentence appears to be incomplete and unrelated to the preceding text.) and As a physical activator, biochar can effectively expand the pore structure under appropriate temperature conditions. By adjusting the ratio of biochar to flue gas, sufficient gas can be ensured to participate in the reaction, promoting the formation of mesopores and even macropores, further improving the adsorption performance of activated carbon. In this embodiment, by precisely controlling the ratio of biochar to ash and flue gas, it is possible to achieve efficient resource utilization, reduce costs, and reduce environmental pollution while ensuring product quality. Furthermore, it allows for the customized production of porous carbon materials with specific properties according to different application requirements.
[0038] According to embodiments of this disclosure, the biomass combustion process includes: burning the biomass under an oxygen-rich environment.
[0039] Furthermore, biomass combustion can be carried out using combustion equipment such as bioburners and fixed beds for oxygen-enriched combustion.
[0040] According to embodiments of this disclosure, pyrolysis of biomass includes: pyrolysis of biomass under anaerobic or hypoxic conditions.
[0041] Furthermore, low-temperature pyrolysis of biomass can be carried out using equipment with controllable atmosphere, such as small tubular furnaces or rotary kilns, under oxygen-deficient or oxygen-free conditions.
[0042] In the embodiments of this disclosure, burning biomass in an oxygen-rich environment can reduce the generation of unburned material and improve energy utilization. Pyrolysis of biomass under anaerobic or oxygen-deficient conditions reduces carbon loss because insufficient oxygen inhibits complete combustion, thereby increasing the carbon content in the final product and improving the yield and quality of biochar. This means that more raw biomass can be converted into biochar instead of being released as carbon dioxide.
[0043] Based on the above embodiments, the pyrolysis temperature in the pyrolysis treatment is 400℃~700℃.
[0044] Furthermore, the pyrolysis temperature in the pyrolysis treatment is 550℃~650℃.
[0045] Furthermore, the activation temperature in the activation reaction is 500℃~1000℃, and the activation time is 0.25h~2h.
[0046] Furthermore, the activation temperature in the activation reaction is 800℃~900℃, and the activation time is 0.5h~1h.
[0047] Furthermore, before the biomass is burned or pyrolyzed, the process also includes pulverizing the biomass. The size of the pulverized biomass can be 0-10 cm, preferably 1 mm-2 mm.
[0048] Biomass can be cotton stalks, fruit trees, fruit shells, straw, etc., but is not limited to these.
[0049] S5 can be prepared by acid washing the second mixture with 2 mol / L hydrochloric acid, washing it with water until neutral, and then drying it in an oven at 80°C.
[0050] The present disclosure will be further described below through specific embodiments.
[0051] Example 1
[0052] a. After crushing the cotton stalks, fine cotton stalk fragments with a particle size of 1mm-5mm are obtained. After crushing the walnut shells, powder is obtained.
[0053] b. A certain amount of cotton stalks obtained in step a are burned through a burner or a fixed bed to achieve heat output and obtain ash and flue gas. The flue gas is collected through a gas bag.
[0054] In addition, a certain amount of walnut shell powder is weighed and subjected to oxygen-free or partially oxygen-free pyrolysis in a tubular furnace or pyrolysis furnace to obtain biochar.
[0055] c. Mix the biochar and ash obtained in step a in a certain proportion and place them in pyrolysis equipment (tube furnace, rotary kiln, etc.) while introducing flue gas for activation reaction.
[0056] d. The sample obtained in step c is subjected to grinding, acid washing, drying and other processes to finally obtain biomass-based activated carbon material.
[0057] In step a, the biomass can be cotton stalks or walnut shells.
[0058] Examples 2-11
[0059] Examples 2 to 11 are based on Example 1. The parameters of Examples 1 to 11 are shown in Table 1.
[0060] Comparative Example 1
[0061] Based on Example 11, except that no ash is added, all other components and parameters are the same as in Example 11.
[0062] Comparative Example 2
[0063] Based on Example 11, except that no flue gas was added, all other components and parameters were the same as in Example 11.
[0064] The specific surface area of the products prepared in Examples 1-11 and Comparative Examples 1-2 was measured, and the results are shown in Table 1.
[0065] Table 1
[0066]
[0067] Table 1 shows that Examples 1-3 indicate that the biochar-to-ash ratio of 5:1 yields the highest specific surface area of biomass-based activated carbon, at 1809 m² / g. Examples 4-5 show that a biochar-to-flue gas ratio of 300:1 to 400:1 provides better activation; a ratio that is too low (50:1) significantly reduces the specific surface area of the biomass-based activated carbon. Comparative Examples 1-2 and Example 11 demonstrate that using both ash and flue gas as activators effectively increases the specific surface area of biomass-based activated carbon; the absence of either ash or flue gas results in a significant decrease in specific surface area.
[0068] Figure 2 A scanning electron microscope image of biomass-based activated carbon according to Example 1 of this disclosure is shown schematically.
[0069] Depend on Figure 2 As can be seen, the biomass-based activated carbon in this embodiment is irregularly shaped and has abundant pores left by flue gas and ash etching on its surface, indicating that the material has a high specific surface area.
[0070] Figure 3 A scanning electron microscope image of biomass-based activated carbon according to Embodiment 11 of this disclosure is shown schematically.
[0071] Depend on Figure 3 As can be seen, the biomass-based activated carbon in this embodiment has an irregular block structure, and the surface pores of the biomass-based activated carbon are clearly visible, with many microporous structures.
[0072] Figure 4 A transmission electron microscope (TEM) image of biomass-based activated carbon according to Embodiment 11 of this disclosure is shown schematically.
[0073] Depend on Figure 4 As can be seen, the high-resolution TEM image of this embodiment shows disordered amorphous carbon features with abundant micropores on its surface.
[0074] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.
Claims
1. A method for preparing biomass-based activated carbon, characterized in that, include: Biomass is burned, and the ash and flue gas after combustion are collected. Biochar is obtained by pyrolyzing biomass. The biochar and the ash are mixed to obtain a first mixture; The flue gas is added to the first mixture to carry out an activation reaction, thereby obtaining a second mixture; The second mixture is subjected to acid washing, water washing and drying to obtain the biomass-based activated carbon.
2. The preparation method according to claim 1, characterized in that, The mass ratio of the biochar to the ash is (0.5~10):
1.
3. The preparation method according to claim 1, characterized in that, The volume ratio of the biochar to the flue gas is (50~400):
1.
4. The preparation method according to claim 1, characterized in that, The process of burning biomass includes: The biomass is burned under oxygen-enriched conditions.
5. The preparation method according to claim 1, characterized in that, The process of pyrolyzing biomass includes: The biomass is subjected to pyrolysis under anaerobic or oxygen-deficient conditions.
6. The preparation method according to claim 1, characterized in that, The pyrolysis temperature in the pyrolysis treatment is 400℃~700℃.
7. The preparation method according to claim 6, characterized in that, The pyrolysis temperature in the pyrolysis treatment is 550℃~650℃.
8. The preparation method according to claim 1, characterized in that, The activation temperature in the activation reaction is 500℃~1000℃, and the activation time is 0.25h~2h.
9. The preparation method according to claim 8, characterized in that, The activation temperature in the activation reaction is 800℃~900℃, and the activation time is 0.5h~1h.
10. The preparation method according to claim 1, characterized in that, Before the biomass is subjected to combustion or pyrolysis, the method further includes: pulverizing the biomass.