Method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass

Abstract

The invention discloses a method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass. The method comprises the following steps: uniformly mixing urea resin solid powder, biomass and an activating agent; placing the mixed material in inert atmosphere protection, and carrying out temperature programming to 500-800 DEG C to carry out co-pyrolysis reaction; after the pyrolysis is completed, cooling, washing and drying to obtain the carbon material. According to the invention, one-step co-pyrolysis of urea-formaldehyde resin and biomass is utilized, effective doping of nitrogen element is realized at a relatively low temperature, in-situ molding of the material is realized by utilizing the thermosetting characteristic of urea-formaldehyde resin, and a molded carbon material with good mechanical strength can be obtained without an additional binder; the alkalescent potassium salt is selected as the activating agent and is environment-friendly, the prepared carbon material has high specific surface area and ultrahigh microporosity, the CO2 adsorption capacity is remarkably improved, the process is simple, and the energy consumption is low.

Description

Technical Field

[0001] This invention belongs to the field of biochar preparation technology, specifically relating to a method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass. Background Technology

[0002] With the increasingly severe global carbon emission problem, carbon capture, utilization, and storage (CVC) technologies have become a research focus. Porous carbon materials, due to their high specific surface area, tunable pore structure, and good stability, are widely used for CO2 adsorption. To improve adsorption performance, heteroatom doping (such as nitrogen) has proven to be an effective strategy. However, existing methods for preparing nitrogen-doped carbon materials typically require post-processing at high temperatures (>700℃) (such as high-temperature ammonia treatment) or pyrolysis using nitrogen-containing precursors, resulting in high energy consumption and complex processes, and making it difficult to achieve efficient and uniform nitrogen doping at lower temperatures. Furthermore, traditional pore-forming activators (such as KOH and H3PO4) are highly corrosive, easily causing environmental pollution, and the post-processing is complex. On the other hand, most carbon materials are in powder form, with poor formability, and there is a lack of a one-step preparation method for shaped carbon materials that combine high adsorption performance with good mechanical strength. Therefore, there is an urgent need to develop a simple, environmentally friendly method that can prepare nitrogen-doped carbon materials with good mechanical strength and high adsorption performance. Summary of the Invention

[0003] To address at least one of the aforementioned problems, the present invention provides a method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass.

[0004] To achieve the above objectives, the present invention employs the following technical means: This invention provides a method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass, comprising the following steps: S1. Place 1-2 parts of urea-formaldehyde resin solid powder, 1-2 parts of biomass and 3 parts of activator in a grinder and grind and mix thoroughly until uniform; S2. The ground mixture is placed in an inert atmosphere and heated to a pyrolysis temperature of 500~800℃ at a heating rate of 5-10℃ / min, and held at that temperature for 1-2 hours to carry out the co-pyrolysis reaction. S3. After pyrolysis is complete, the product is naturally cooled to room temperature to obtain a black solid product. S4. Wash the solid product repeatedly with deionized water and filter it until the filtrate is neutral. S5. Dry the washed solid product at 90-105℃ for 6-12 hours to obtain nitrogen-doped biochar.

[0005] In some embodiments of the present invention, the biomass is corn cob powder. Using agricultural waste corn cobs as a carbon source achieves value-added utilization of resources, and the specific pore structure of corn cob powder is beneficial for forming a hierarchical porous structure when combined with resin.

[0006] In some embodiments of the present invention, the activator is one of potassium bicarbonate, potassium carbonate, or potassium acetate. Using a weakly basic potassium salt as the activator is less corrosive and more environmentally friendly than traditional strong alkalis such as KOH, and it can synergistically form a high specific surface area and ultra-high microporosity with urea-formaldehyde resin and biomass.

[0007] In some embodiments of the present invention, in step S1, the mass ratio of urea-formaldehyde resin solid powder, biomass, and activator is 1:1:3.

[0008] In some embodiments of the present invention, the pyrolysis temperature is 600-700°C.

[0009] In some embodiments of the present invention, the inert atmosphere is nitrogen gas, with a flow rate of 100-200 mL / min. By controlling the nitrogen gas flow rate, oxygen is effectively isolated, excessive oxidation of the material is prevented, and the carbonization yield and structural integrity of the carbon material are guaranteed.

[0010] A second aspect of the present invention provides a method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass, using the method described in the first aspect.

[0011] The third aspect of the invention provides the application of the nitrogen-doped biochar described in the second aspect in carbon capture.

[0012] Beneficial effects of the present invention Compared with the prior art, the present invention has the following beneficial effects: This invention provides a simple, environmentally friendly method for preparing nitrogen-doped molded carbon materials. It utilizes the nitrogen-containing active substances generated during the pyrolysis of urea-formaldehyde resin. Nitrogen elements (in the form of pyridine nitrogen, pyrrole nitrogen, etc.) can be effectively doped into the carbon framework at a relatively low temperature of 600℃, thus avoiding the high energy consumption caused by high-temperature post-processing. The process is simpler and more environmentally friendly. Simultaneously, urea-formaldehyde resin acts as a carbon source, nitrogen source, and binder during pyrolysis, eliminating the need for additional binders to mold the material and imparting good compressive strength, facilitating practical applications. The nitrogen-containing substances such as pyridine nitrogen, pyrrole nitrogen, and graphitic nitrogen introduced through pyrolysis... This method effectively enhances the alkalinity of the material surface, thereby improving its selective adsorption capacity for CO2. Using corn cob powder, a biomass waste, as the main carbon source, it achieves value-added utilization of resources. The selection of potassium bicarbonate as an activator offers advantages over traditional activators such as KOH, including lower corrosivity and a more environmentally friendly approach. Furthermore, it synergistically interacts with urea-formaldehyde resin and corn cob powder to form a porous structure with high specific surface area and ultra-high microporosity, significantly improving CO2 adsorption capacity. The one-step co-pyrolysis method eliminates the need for pre-carbonization or post-modification steps, further reducing energy consumption and process complexity. Moreover, the corn cob raw material is agricultural waste, realizing the resource utilization of waste. Attached Figure Description

[0013] Figure 1 The images shown are SEM images of the materials prepared in Example 1 and the comparative example of this invention. Figure 2 This is a comparison chart of the CO2 adsorption capacity of biochar prepared in Examples 1-3 and Comparative Example 6 of the present invention; Figure 3 This is a comparison chart of CO2 adsorption capacity of biochar prepared at different pyrolysis temperatures in Examples 1 and 4-6 of this invention; Figure 4 This is a comparison chart of the CO2 adsorption performance of the materials prepared in Example 1 and Comparative Examples 1 and 2 of the present invention; Figure 5 This is a comparison chart of the CO2 adsorption performance of materials prepared from different thermosetting plastics in Example 1 and Comparative Examples 3-5 of the present invention; Figure 6 This is a comparison chart of the adsorption performance of one-step pyrolysis in Example 1 and two-step pyrolysis in Comparative Example 6 of the present invention; Figure 7 This is a cyclic stability test diagram of Embodiment 1 of the present invention. Detailed Implementation

[0014] The following examples are used to illustrate preferred embodiments of the invention. Those skilled in the art will understand that the techniques disclosed in the examples represent techniques discovered by the inventors that can be used to implement the invention, and therefore can be considered preferred embodiments for implementing the invention. However, those skilled in the art should understand from this specification that many modifications can be made to the specific embodiments disclosed herein, still yielding the same or similar results, without departing from the spirit or scope of the invention.

[0015] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and all materials disclosed herein are incorporated herein by reference. Many equivalent techniques of specific embodiments of the invention described herein will be recognized or can be understood by those skilled in the art through conventional experimentation. These equivalents will be included in the claims.

[0016] The technical solution of this application will be further described in detail below with reference to specific embodiments.

[0017] Example 1 Accurately weigh 2g of urea-formaldehyde resin solid powder, 2g of corn cob powder, and 6g of potassium bicarbonate, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 600℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and maintain this temperature for 1 hour. After pyrolysis, allow it to cool naturally to room temperature. Repeatedly wash and filter the resulting black solid with deionized water until the filtrate is neutral. Dry the solid product in an oven at 105℃ for 12 hours to obtain the carbon material.

[0018] Example 2 Accurately weigh 2g of urea-formaldehyde resin solid powder, 2g of corn cob powder, and 6g of potassium carbonate, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 600℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and maintain this temperature for 1 hour. After pyrolysis, allow it to cool naturally to room temperature. Repeatedly wash and filter the resulting black solid with deionized water until the filtrate is neutral. Dry the solid product in an oven at 105℃ for 12 hours to obtain the carbon material.

[0019] Example 3 Accurately weigh 2g of urea-formaldehyde resin solid powder, 2g of corn cob powder, and 6g of potassium acetate, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 600℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and maintain this temperature for 1 hour. After pyrolysis, allow it to cool naturally to room temperature. Repeatedly wash and filter the resulting black solid with deionized water until the filtrate is neutral. Dry the solid product in an oven at 105℃ for 12 hours to obtain the carbon material.

[0020] Example 4 Accurately weigh 2g of urea-formaldehyde resin solid powder, 2g of corn cob powder, and 6g of potassium bicarbonate, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 500℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and maintain this temperature for 1 hour. After pyrolysis, allow it to cool naturally to room temperature. Repeatedly wash and filter the resulting black solid with deionized water until the filtrate is neutral. Dry the solid product in an oven at 105℃ for 12 hours to obtain the carbon material.

[0021] Example 5 Accurately weigh 2g of urea-formaldehyde resin solid powder, 2g of corn cob powder, and 6g of potassium bicarbonate, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 700℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and maintain this temperature for 1 hour. After pyrolysis, allow it to cool naturally to room temperature. Repeatedly wash and filter the resulting black solid with deionized water until the filtrate is neutral. Dry the solid product in an oven at 105℃ for 12 hours to obtain the carbon material.

[0022] Example 6 Accurately weigh 2g of urea-formaldehyde resin solid powder, 2g of corn cob powder, and 6g of potassium bicarbonate, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 800℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and maintain this temperature for 1 hour. After pyrolysis, allow it to cool naturally to room temperature. Repeatedly wash and filter the resulting black solid with deionized water until the filtrate is neutral. Dry the solid product in an oven at 105℃ for 12 hours to obtain the carbon material.

[0023] Comparative Example 1 Accurately weigh 4g of urea-formaldehyde resin solid powder and 6g of potassium bicarbonate, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 600℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and maintain this temperature for 1 hour. After pyrolysis, allow it to cool naturally to room temperature. Wash the resulting black solid repeatedly with deionized water and filter until the filtrate is neutral. Dry the solid product in an oven at 105℃ for 12 hours to obtain the carbon material.

[0024] Comparative Example 2 Accurately weigh 4g of corn cob powder and 6g of potassium bicarbonate, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 600℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and maintain this temperature for 1 hour. After pyrolysis, allow it to cool naturally to room temperature. Repeatedly wash and filter the resulting black solid with deionized water until the filtrate is neutral. Dry the solid product in an oven at 105℃ for 12 hours to obtain the carbon material.

[0025] Comparative Example 3 Accurately weigh 2g of melamine-formaldehyde resin solid powder, 2g of corn cob powder, and 6g of potassium bicarbonate, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 600℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and maintain this temperature for 1 hour. After pyrolysis, allow it to cool naturally to room temperature. Repeatedly wash and filter the resulting black solid with deionized water until the filtrate is neutral. Dry the solid product in an oven at 105℃ for 12 hours to obtain the carbon material.

[0026] Comparative Example 4 Accurately weigh 2g of epoxy resin solid powder, 2g of corn cob powder, and 6g of potassium bicarbonate, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 600℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and maintain this temperature for 1 hour. After pyrolysis, allow it to cool naturally to room temperature. Repeatedly wash and filter the resulting black solid with deionized water until the filtrate is neutral. Dry the solid product in an oven at 105℃ for 12 hours to obtain the carbon material.

[0027] Comparative Example 5 Accurately weigh 2g of phenolic resin solid powder, 2g of corn cob powder, and 6g of potassium bicarbonate, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 600℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and maintain this temperature for 1 hour. After pyrolysis, allow it to cool naturally to room temperature. Repeatedly wash and filter the resulting black solid with deionized water until the filtrate is neutral. Dry the solid product in an oven at 105℃ for 12 hours to obtain the carbon material.

[0028] Comparative Example 6 Accurately weigh 2g of urea-formaldehyde resin solid powder and 2g of corn cob powder, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 600℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and hold at this temperature for 1 hour. After pyrolysis, allow it to cool naturally to room temperature. Mix the carbon precursor with potassium bicarbonate in a 1:3 ratio, and physically grind and mix them in a mortar for 20 minutes. Heat the mixture to 600℃ under a nitrogen flow of 100mL / min at a heating rate of 10℃ / min, and hold at this temperature for 1 hour. Repeatedly wash the resulting black solid with deionized water and filter until the filtrate is neutral. Dry the solid product in an oven at 105℃ for 12 hours to obtain the carbon material.

[0029] Performance testing (1) The materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 were compared using scanning electron microscopy. The results are as follows: Figure 1 As shown.

[0030] The results are as follows Figure 1 As shown in (a), the material in Comparative Example 1 has a dense structure and poor porosity; Figure 1 As shown in (b), the material of Example 1 exhibits a rich and well-developed pore structure on its surface, with relatively uniform pore distribution; Figure 1 As shown in (c), the material in Comparative Example 2 is a loose powder that is difficult to form and has low adsorption performance.

[0031] (2) The CO2 adsorption performance of the biochar prepared in Examples 1, 2, 3 and Comparative Example 6 was tested to investigate the effect of the type of activator. The results are as follows: Figure 2 As shown.

[0032] The results showed that, compared to Example 1 using potassium bicarbonate, the CO2 adsorption capacity of the materials obtained in Example 2 using potassium carbonate, Example 3 using potassium acetate, and Comparative Example 6 without an activator was significantly reduced. The material prepared in Example 1 using potassium bicarbonate exhibited the best CO2 adsorption performance, with an adsorption capacity of 3.05 mmol / g. In contrast, the material prepared using potassium carbonate had a CO2 adsorption capacity of approximately 2.1 mmol / g, and the material prepared using potassium acetate had a CO2 adsorption capacity of approximately 1.9 mmol / g.

[0033] Potassium bicarbonate, during pyrolysis, not only acts as a chemical activator but also decomposes to release carbon dioxide and water vapor. These gases, during their escape, physically create pores, contributing to a richer microporous structure. Furthermore, its relatively mild alkalinity avoids excessive etching of the carbon framework by a strong alkali, thus preserving more micropores for CO2 adsorption. In contrast, while potassium carbonate exhibits better activation, its relatively strong alkalinity may cause some micropore walls to collapse or expand into mesopores, reducing the micropore volume crucial for CO2 adsorption. Potassium acetate has relatively low activation efficiency and limited pore-forming ability. These results indicate that potassium bicarbonate, in the system of this invention, combines excellent activation and pore-forming capabilities with environmental friendliness, making it a suitable green activator.

[0034] (3) The CO2 adsorption performance of the biochar prepared in Examples 1, 4, 5, and 6 was tested to investigate the effect of pyrolysis temperature. The results are as follows: Figure 3 As shown in Table 1, the pore structure performance was tested.

[0035] Table 1. Characterization results of pore structure of carbon materials

[0036] Note: The process of producing biochar materials by co-pyrolysis of corncob powder and urea-formaldehyde resin is abbreviated as CUBC.

[0037] The results show that this series of carbon materials (CUBC) exhibits a typical temperature-dependent structural evolution: as the pyrolysis temperature increases from 500℃ to 800℃, the specific surface area of ​​the material shows a significant increasing trend. When the pyrolysis temperature is 500℃, the specific surface area of ​​the material is only 103.54 m². 2 / g, total pore volume is 0.08cm³ 3 The surface area was approximately 0 m² / g, and the specific surface area of ​​the ultrapores was almost zero, indicating that the activation reaction had not yet fully occurred and the pore structure was not fully developed. When the temperature was increased to 600℃, the specific surface area jumped to 726.57 m² / g. 2 / g, and the specific surface area of ​​the ultra-micropores reaches a peak of 408.41m². 2 / g, with an ultramicropore volume of 0.13cm³. 3 The concentration of 1012 / g indicates that the activator reacts violently with the carbon skeleton at this temperature, forming a large number of ultraporous structures that are conducive to CO2 adsorption. When the temperature is further increased to 700℃, the specific surface area continues to increase to 1012.56 m2 2 / g, but the specific surface area of ​​the ultrafine pores began to decrease to 132.77m².2 / g, the total pore volume increased significantly to 0.72cm³. 3 / g, indicating that high temperature promotes the ablation of the pore walls, causing some micropores to expand into mesopores or macropores. When the temperature reaches 800℃ or even higher, although the specific surface area remains at a high level of 1314.86m², 2 / g, but the collapse of the ultraporous structure further decreased, and the specific surface area of ​​the ultraporous pores dropped to 98.43m². 2 / g.

[0038] The micropore size matches well with the dynamic diameter of CO2 molecules (0.33 nm), which facilitates the diffusion of the adsorbate. Figure 3 Regarding CO2 adsorption performance, the adsorption capacity showed a high degree of consistency with the trend of changes in the microporous structure. The material prepared at 500℃ exhibited the lowest CO2 adsorption capacity, approximately 1.02 mmol / g, due to the scarcity of micropores. The material prepared at 600℃, with its most developed microporous structure, demonstrated the best CO2 adsorption performance, reaching an adsorption capacity of 3.05 mmol / g. Although the material prepared at 700℃ had a larger specific surface area, its CO2 adsorption capacity decreased slightly to approximately 2.93 mmol / g due to the reduced proportion of micropores. As the temperature continued to rise to 800℃, the microporous structure was further damaged, leading to a significant decrease in adsorption capacity, approximately 2.35 mmol / g.

[0039] The above experimental data fully demonstrate that pyrolysis temperature is a key parameter for controlling the pore structure of carbon materials. Within the range of 500–800℃, the method described in this invention can prepare carbon materials with adsorption properties. The optimal pyrolysis temperature range is 600–700℃, within which the activation reaction and micropore formation reach an optimal balance, enabling the preparation of carbon materials with both high specific surface area and abundant ultramicroporous structure, thereby achieving the best CO2 adsorption effect.

[0040] It should also be understood that although specific temperature values ​​are listed in this embodiment, in actual applications, the pyrolysis temperature can be adaptively adjusted within the range of 500~800℃ according to the characteristics of the raw materials or the target performance requirements. For example, it can be set to 550℃, 650℃ or 750℃, etc., all of which fall within the protection scope of this invention.

[0041] (4) Comparison of CO2 adsorption performance of materials prepared in Example 1, Comparative Example 1 and Comparative Example 2 Figure 4 As shown.

[0042] The results showed that the CO2 adsorption capacities of the materials prepared in Comparative Example 1 and Comparative Example 2 were 2.25 mmol / g and 2.6 mmol / g, respectively, significantly lower than the 3.05 mmol / g of Example 1. Comparative Example 1, lacking biomass as the main carbon skeleton source, relied solely on the dense carbon structure formed by resin pyrolysis, resulting in insufficient pore development and limited specific surface area and pore volume, thus reducing adsorption performance. This demonstrates the crucial role of biomass components in constructing porous structures.

[0043] As can be seen from the SEM images, urea-formaldehyde resin in this invention not only introduces alkaline sites as a nitrogen source to enhance CO2 affinity, but more importantly, its thermosetting properties act as an in-situ binder during pyrolysis, giving the material excellent molding properties and mechanical strength, which cannot be achieved by simple biomass carbonization.

[0044] (5) The compressive strength of Example 1 and commercial activated carbon were tested, and the results are shown in Table 2.

[0045] Table 2. Compressive strength test results of carbon materials

[0046] The results show that the mechanical strength of the carbon material prepared by this invention is significantly better than that of commercial products, meeting the requirements of industrial applications. It also shows that urea-formaldehyde resin, as an in-situ binder, can form the material without the need for additional binders. This solves the technical bottleneck of traditional powdered carbon materials being difficult to form and having low mechanical strength, and expands its application potential in fixed-bed carbon capture devices.

[0047] (6) A systematic comparison was made of the materials prepared in Example 1, Comparative Example 3, Comparative Example 4 and Comparative Example 5, and the results are as follows: Figure 5 As shown.

[0048] The results showed that urea-formaldehyde resin had significantly better CO2 adsorption performance than the other three thermosetting resins. Comparative Example 3 showed a 21.3% decrease in CO2 adsorption compared to Example 1, Comparative Example 4 a 41% decrease, and Comparative Example 5 a 67.2% decrease. Urea-formaldehyde resin contains a large number of CN and N-N bonds, which generate active nitrogen-containing species during pyrolysis at 600℃, contributing to the formation of abundant micropores, while also exhibiting high nitrogen doping efficiency. Although melamine-formaldehyde resin has a high nitrogen content, its complex structure and the numerous condensation products generated during pyrolysis easily clog pores, leading to a decrease in micropore volume. Epoxy and phenolic resins contain no nitrogen or have low nitrogen content, failing to provide sufficient alkaline sites.

[0049] The nitrogen content of thermosetting plastics is not the only determining factor; crucial factors also include pyrolysis temperature, whether the decomposition products are conducive to pore formation, and the uniformity and efficiency of nitrogen doping. Although urea-formaldehyde resin has a lower nitrogen content than melamine-formaldehyde resin, its pyrolysis characteristics are perfectly matched with corn cob powder. The two work synergistically during pyrolysis, and neither can be dispensed with. The unique molecular structure and pyrolysis characteristics of urea-formaldehyde resin give it significant advantages in nitrogen doping efficiency and pore control.

[0050] (7) The adsorption performance of the materials prepared in Example 1 and Comparative Example 6 was compared, and the results are as follows: Figure 6 As shown.

[0051] The results show that the one-step pyrolysis method has dual advantages over the two-step pyrolysis method: improving material performance and simplifying the production process. Firstly, the material in Example 1 exhibits optimal CO2 adsorption performance; secondly, the one-step pyrolysis method reduces the number of heating cycles and lowers energy consumption. In the one-step process, the activator and raw materials are heated simultaneously. The activator can intervene in pore formation at the initial stage of pyrolysis and bond breaking of organic macromolecules, effectively preventing pore blockage and promoting uniform nitrogen doping. In contrast, in the two-step method, the pre-carbonization process has already formed a relatively stable carbon structure, making it difficult for subsequent activation to fully open the pores. Furthermore, multiple heat treatments increase energy consumption and may lead to the collapse of the pore structure.

[0052] (8) Cyclic stability tests were performed on the material prepared in Example 1, and the results are as follows: Figure 7 As shown.

[0053] The results showed that the CO2 adsorption capacity retention rate reached over 90% after 5 cycles. This cycling stability indicates that the adsorbent possesses good regeneration capacity and structural stability, making it highly valuable for industrial applications. This is because the carbon skeleton structure formed by the urea-formaldehyde resin during pyrolysis is relatively stable, and the mild activation effect of potassium bicarbonate prevents pore structure collapse caused by excessive etching, allowing the material to maintain the integrity of its pore structure during multiple gas adsorption and desorption cycles.

[0054] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by this application.

Claims

1. A method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass, characterized in that, Includes the following steps: S1. Place 1-2 parts of urea-formaldehyde resin solid powder, 1-2 parts of biomass and 3 parts of activator in a grinder and grind and mix thoroughly until uniform; S2. The ground mixture is placed in an inert atmosphere and heated to a pyrolysis temperature of 500~800℃ at a heating rate of 5-10℃ / min, and held at that temperature for 1-2 hours to carry out the co-pyrolysis reaction. S3. After pyrolysis is complete, the product is naturally cooled to room temperature to obtain a black solid product. S4. Wash the solid product repeatedly with deionized water and filter it until the filtrate is neutral. S5. Dry the washed solid product at 90-105℃ for 6-12 hours to obtain nitrogen-doped biochar.

2. The method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass according to claim 1, characterized in that, The biomass is corn cob powder.

3. The method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass according to claim 1, characterized in that, The activator is one of potassium bicarbonate, potassium carbonate, or potassium acetate.

4. The method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass according to claim 1, characterized in that, In step S1, the mass ratio of urea-formaldehyde resin solid powder, biomass, and activator is 1:1:

3.

5. The method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass according to claim 1, characterized in that, The pyrolysis temperature is 600-700℃.

6. The method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass according to claim 1, characterized in that, The inert atmosphere is nitrogen, with a flow rate of 100-200 mL / min.

7. A method for preparing nitrogen-doped biochar based on one-step co-pyrolysis of thermosetting resin and biomass, characterized in that, It is prepared by the method described in any one of claims 1-6.

8. The application of the nitrogen-doped biochar according to claim 7 in carbon capture.

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