Biomass-based porous carbon material as well as preparation method and application thereof

Abstract

The invention discloses a biomass-based porous carbon material as well as a preparation method and application thereof, and belongs to the technical field of preparation of porous carbon materials. The method comprises the following steps: dissolving a phosphorus source and a carbon source in a solvent, and drying to obtain a pyrolysis precursor; and carrying out temperature programming pyrolysis on the precursor in an air atmosphere to obtain the product. According to the method, a phosphorus source and carbon source synergistic carbonization system is constructed, and the dual effects that the phosphorus source forms a compact carbon layer to isolate oxygen at a low-temperature stage and forms a stable POC bond with a carbon skeleton at a high-temperature stage are utilized, so that stable carbonization of the biomass carbon source is successfully realized in an air atmosphere, and the dependence of a traditional process on an inert atmosphere is broken through. The prepared porous carbon material has excellent specific surface area and structural stability, and can be widely applied to the fields of electromagnetic wave absorption, pollutant adsorption, catalytic carriers and the like.

Description

A biomass-based porous carbon material, its preparation method and application Technical Field

[0001] This invention belongs to the field of porous carbon material preparation technology, specifically relating to a biomass-based porous carbon material, its preparation method, and its application. Background Technology

[0002] Porous carbon materials, due to their large specific surface area, tunable pore structure, electrical conductivity, and excellent physicochemical properties, have shown broad application prospects in many fields such as adsorption separation, heterogeneous catalysis, energy storage and conversion, and electromagnetic wave shielding and absorption, making them one of the current research hotspots in materials science. With the rapid development of the electronics and information industry, the environmental protection industry, and the new energy industry, the market demand for porous carbon materials continues to grow, while simultaneously placing higher demands on their preparation cost, production efficiency, and performance stability.

[0003] There are numerous methods for preparing porous carbon materials, including template methods, activation methods, carbonization methods, and self-assembly methods. Among these, carbonization is one of the most widely used methods due to its relatively simple process and ease of control. Traditional methods for preparing porous carbon materials often rely on high-temperature pyrolysis or high-pressure reaction processes under an oxygen-free inert atmosphere. These processes have several problems: firstly, creating an inert atmosphere requires specialized sealing equipment and a continuous supply of inert gas, resulting in high equipment investment and operating costs; secondly, high-pressure reactions place stringent requirements on the pressure resistance of the equipment, further limiting the expansion of production scale and making it difficult to achieve low-cost, large-scale mass production of porous carbon materials. Furthermore, carbon source materials containing only non-metallic elements such as C, H, O, and N are easily oxidized and decomposed into carbon dioxide, water, and other products in high-temperature air environments, failing to form a stable carbon framework structure. This characteristic has become a core bottleneck restricting the direct preparation of porous carbon materials in air.

[0004] Biomass feedstocks, as a widely available, environmentally friendly, and low-cost renewable carbon source, have great potential in the field of porous carbon material preparation. However, existing air atmosphere preparation technologies cannot adapt to the complex composition of biomass feedstocks, resulting in the preparation of biomass-based porous carbon still relying on inert atmosphere processes, which limits the high-value utilization of biomass resources.

[0005] The application of phosphorus-containing flame retardants in the field of polymer flame retardancy is relatively mature. Their flame retardant mechanisms mainly include two aspects: gas-phase flame retardancy and condensed-phase flame retardancy. In the gas phase, phosphorus-containing flame retardants decompose upon heating, releasing phosphorus free radicals. These free radicals can efficiently capture the H· and OH· active free radicals generated during polymer combustion, interrupting the combustion chain reaction. Simultaneously, they release non-combustible gases such as carbon dioxide and water, diluting the concentration of combustible gases and air, further inhibiting the spread of combustion. In the condensed phase, phosphorus-containing flame retardants can promote the dehydration and carbonization reaction of polymers at high temperatures, forming a dense, continuous char layer. This char layer can block heat transfer and oxygen penetration, protecting the internal polymer from further combustion. Simultaneously, phosphorus can catalyze the carbonization reaction, improving the density and thermal stability of the char layer.

[0006] Based on the above background, if the mechanism by which phosphorus-containing flame retardants promote char formation and stabilize carbon structure in the condensed phase can be applied to the biomass carbonization process, it is expected that the direct conversion of biomass carbon sources into stable porous carbon materials can be achieved in an air atmosphere. This would overcome the dependence of existing processes on inert atmospheres and promote the development of low-cost, large-scale, and environmentally friendly biomass-based porous carbon material preparation technology. Summary of the Invention

[0007] In view of the above-mentioned prior art, the present invention discloses a biomass-based porous carbon material and its preparation method and application, so as to solve the technical problem that the preparation of porous carbon materials in the prior art mostly depends on high-temperature pyrolysis or high-pressure reaction process under an oxygen-free inert atmosphere, and the carbon skeleton of the prepared porous carbon material has poor stability.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is to provide a method for preparing biomass-based porous carbon materials, which includes the following steps: S1: dissolving a phosphorus source and a carbon source in a solvent to obtain a mixed solution, drying the mixed solution until the solvent is completely evaporated to obtain a pyrolysis precursor; the phosphorus source is selected from one or more of phytic acid, triphenylphosphine, phosphoric acid, and polyphosphoric acid; the carbon source is selected from one or more of tannic acid, glucose, xylose, gelatin, ammonium alginate, chitosan, and lignin; S2: placing the pyrolysis precursor in an air atmosphere for programmed temperature pyrolysis to obtain the material; the programmed temperature pyrolysis includes: heating at a rate of 5~6℃ / min to 700℃, and then holding at that temperature for 1h.

[0009] Based on the above technical solution, the present invention can be further improved as follows: In step S1, the solvent is deionized water or ethanol, and the ratio of phosphorus source, carbon source and solvent is 0.4~0.6g:4~6g:60mL.

[0010] Furthermore, the drying temperature in step S1 is 55~65℃.

[0011] This invention also discloses the application of biomass-based porous carbon materials in electromagnetic wave shielding and absorption, water pollutant adsorption, gas separation, or as a catalyst carrier.

[0012] The beneficial effects of this invention are: 1. Innovative process, mild conditions, and controllable cost: This invention constructs a "phosphorus source-carbon source" synergistic carbonization system, which does not require inert atmosphere protection or the addition of transition metal anchoring ligands throughout the preparation process. The pyrolysis reaction is completed directly in an open air environment, which provides the possibility for low-cost preparation of porous carbon materials.

[0013] 2. Wide applicability of raw materials, environmentally friendly and renewable: The method of this invention is applicable to a variety of phosphorus and carbon sources, and is especially suitable for various biomass raw materials and biomass derivatives. The raw materials are widely available, environmentally friendly and low cost. It not only broadens the range of raw material selection for porous carbon materials, but also realizes the high-value utilization of biomass resources, which is in line with the development trend of green and low-carbon industries.

[0014] 3. Excellent product performance and wide range of applications: In this invention, the phosphorus source plays a dual role of "low-temperature carbonization barrier and high-temperature bonding stabilization." At low temperatures (200~400℃), it dehydrates and expands to form a dense carbon layer, effectively blocking oxygen and heat from spreading into the carbon source and preventing its oxidation and decomposition. At high temperatures (700℃), it forms stable POC and other bonded structures with the carbon skeleton, significantly enhancing the thermal stability, structural integrity, and conductivity of the carbon skeleton. The prepared porous carbon material can be widely used in various fields such as electromagnetic wave shielding and absorption, water pollutant adsorption, gas separation, and catalyst support. Attached Figure Description

[0015] Figure 1 shows the SEM images of the porous carbon materials prepared in Examples 1-4; Figure 2 shows the SEM images of the porous carbon materials prepared in Examples 5-8; Figure 3 shows the elemental distribution of the porous carbon materials prepared in Examples 1-4; Figure 4 shows the reflectance loss curves of the porous carbon materials prepared in Example 1 at different thicknesses. Detailed Implementation

[0016] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0017] Example 1: A biomass-based porous carbon material was prepared by the following steps: S1: 0.5g phytic acid and 5g tannic acid were dissolved in 60mL of deionized water, and then stirred at 60℃ until the deionized water was completely removed to obtain a pyrolysis precursor; S2: The pyrolysis precursor was placed in a ceramic crucible with the crucible open, without sealing, and then placed in a muffle furnace for programmed temperature pyrolysis in an open air environment; the heating rate was set to 5℃ / min, from room temperature to 700℃, and then held at a constant temperature for 1h. During the pyrolysis process, the precursor was observed to soften and expand first, and then gradually carbonize and turn black, with no obvious smoke or odor produced; after the pyrolysis was completed, the muffle furnace was turned off and allowed to cool naturally to room temperature to obtain a black powdery biomass-based porous carbon material, labeled as P / PC-1.

[0018] Example 2: A biomass-based porous carbon material was prepared by the following steps: S1: 0.5g of phosphoric acid and 5g of tannic acid were dissolved in 60mL of deionized water, and then stirred at 60℃ until the deionized water was completely removed to obtain a pyrolysis precursor; S2: The pyrolysis precursor was placed in a ceramic crucible with the crucible open, without sealing, and then placed in a muffle furnace for programmed temperature pyrolysis in an open air environment; the heating rate was set to 5℃ / min, from room temperature to 700℃, and then held at a constant temperature for 1h. During the pyrolysis process, the precursor was observed to soften and expand first, and then gradually carbonize and turn black, with no obvious smoke or odor produced; after the pyrolysis was completed, the muffle furnace was turned off and allowed to cool naturally to room temperature to obtain a black powdery biomass-based porous carbon material, labeled as P / PC-2.

[0019] Example 3: A biomass-based porous carbon material was prepared by the following steps: S1: 0.5g of triphenylphosphine and 5g of tannic acid were dissolved in 60mL of deionized water, and then stirred at 60°C until the deionized water was completely removed to obtain a pyrolysis precursor; S2: The pyrolysis precursor was placed in a ceramic crucible with the crucible open, without sealing, and then placed in a tube furnace for programmed temperature pyrolysis in an open air environment; the heating rate was set to 5°C / min, from room temperature to 700°C, and then held at a constant temperature for 1h. During the pyrolysis process, the precursor was observed to soften and expand first, and then gradually carbonize and turn black, with no obvious smoke or odor produced; after the pyrolysis was completed, the tube furnace was closed and allowed to cool naturally to room temperature to obtain a black powdery biomass-based porous carbon material, labeled as P / PC-3.

[0020] Example 4: A biomass-based porous carbon material was prepared by the following steps: S1: 0.5g of polyphosphoric acid and 5g of tannic acid were dissolved in 60mL of deionized water, and then stirred at 60℃ until the deionized water was completely removed to obtain a pyrolysis precursor; S2: The pyrolysis precursor was placed in a ceramic crucible with the crucible open, without sealing, and then placed in a muffle furnace for programmed temperature pyrolysis in an open air environment; the heating rate was set to 5℃ / min, from room temperature to 700℃, and then held at a constant temperature for 1h. During the pyrolysis process, the precursor was observed to soften and expand first, and then gradually carbonize and turn black, with no obvious smoke or odor produced; after the pyrolysis was completed, the muffle furnace was turned off and allowed to cool naturally to room temperature to obtain a black powdery biomass-based porous carbon material, labeled as P / PC-4.

[0021] Example 5: A biomass-based porous carbon material was prepared by the following steps: S1: 0.5g phytic acid and 5g glucose were dissolved in 60mL of deionized water, and then stirred at 60℃ until the deionized water was completely removed to obtain a pyrolysis precursor; S2: The pyrolysis precursor was placed in a ceramic crucible with the crucible open, without sealing, and then placed in a muffle furnace for programmed temperature pyrolysis in an open air environment; the heating rate was set to 5℃ / min, from room temperature to 700℃, and then held at a constant temperature for 1h. During the pyrolysis process, the precursor was observed to soften and expand first, and then gradually carbonize and turn black, with no obvious smoke or odor produced; after the pyrolysis was completed, the muffle furnace was turned off and allowed to cool naturally to room temperature to obtain a black powdery biomass-based porous carbon material, labeled as P / GPC-1.

[0022] Example 6: A biomass-based porous carbon material was prepared by the following steps: S1: 0.5g phytic acid and 5g xylose were dissolved in 60mL of deionized water, and then stirred at 60℃ until the deionized water was completely removed to obtain a pyrolysis precursor; S2: The pyrolysis precursor was placed in a ceramic crucible with the crucible open, without sealing, and then placed in a muffle furnace for programmed temperature pyrolysis in an open air environment; the heating rate was set to 5℃ / min, from room temperature to 700℃, and then held at a constant temperature for 1h. During the pyrolysis process, the precursor was observed to soften and expand first, and then gradually carbonize and turn black, with no obvious smoke or odor produced; after the pyrolysis was completed, the muffle furnace was turned off and allowed to cool naturally to room temperature to obtain a black powdery biomass-based porous carbon material, labeled as P / XPC.

[0023] Example 7: A biomass-based porous carbon material was prepared by the following steps: S1: 0.5g phytic acid and 5g gelatin were dissolved in 60mL of deionized water, and then stirred at 60℃ until the deionized water was completely removed to obtain a pyrolysis precursor; S2: The pyrolysis precursor was placed in a ceramic crucible with the crucible open, without sealing, and then placed in a muffle furnace for programmed temperature pyrolysis in an open air environment; the heating rate was set to 5℃ / min, from room temperature to 700℃, and then held at a constant temperature for 1h. During the pyrolysis process, the precursor was observed to soften and expand first, and then gradually carbonize and turn black, with no obvious smoke or odor produced; after the pyrolysis was completed, the muffle furnace was turned off and allowed to cool naturally to room temperature to obtain a black powdery biomass-based porous carbon material, labeled as P / GPC-2.

[0024] Example 8: A biomass-based porous carbon material was prepared by the following steps: S1: 0.5g phytic acid and 4g ammonium alginate were dissolved in 60mL ethanol, and then stirred at 60℃ until the ethanol was completely removed to obtain a pyrolysis precursor; S2: The pyrolysis precursor was placed in a ceramic crucible with the crucible open, without sealing, and then placed in a muffle furnace for programmed temperature pyrolysis in an open air environment; the heating rate was set to 6℃ / min, from room temperature to 700℃, and then held at a constant temperature for 1h. During the pyrolysis process, the precursor was observed to soften and expand first, and then gradually carbonize and turn black, with no obvious smoke or odor produced; after the pyrolysis was completed, the muffle furnace was turned off and allowed to cool naturally to room temperature to obtain a black powdery biomass-based porous carbon material, labeled as P / APC.

[0025] Example 9: A biomass-based porous carbon material was prepared by the following steps: S1: 0.6 g of phytic acid and 5 g of chitosan were dissolved in 60 mL of deionized water, and then stirred at 65 °C until the deionized water was completely removed to obtain a pyrolysis precursor; S2: The pyrolysis precursor was placed in a ceramic crucible with the crucible open, without sealing, and then placed in a muffle furnace for programmed temperature pyrolysis in an open air environment; the heating rate was set to 5 °C / min, from room temperature to 700 °C, and then held at a constant temperature for 1 h. During the pyrolysis process, the precursor was observed to soften and expand first, and then gradually carbonize and turn black, with no obvious smoke or odor produced; after the pyrolysis was completed, the muffle furnace was turned off and allowed to cool naturally to room temperature to obtain a black powdery biomass-based porous carbon material.

[0026] Example 10: A biomass-based porous carbon material was prepared by the following steps: S1: 0.4 g of phytic acid and 6 g of lignin were dissolved in 60 mL of deionized water, and then stirred at 55 °C until the deionized water was completely removed to obtain a pyrolysis precursor; S2: The pyrolysis precursor was placed in a ceramic crucible with the crucible open, without sealing, and then placed in a muffle furnace for programmed temperature pyrolysis in an open air environment; the heating rate was set to 5 °C / min, from room temperature to 700 °C, and then held at a constant temperature for 1 h. During the pyrolysis process, the precursor was observed to soften and expand first, and then gradually carbonize and turn black, with no obvious smoke or odor produced; after the pyrolysis was completed, the muffle furnace was turned off and allowed to cool naturally to room temperature to obtain a black powdery biomass-based porous carbon material.

[0027] Compared with Example 1, Comparative Example 1 lacked a phosphorus source and used only tannic acid as a carbon source. It was carbonized under the pyrolysis conditions of Example 1 (700°C, 1h, air atmosphere, heating rate 5°C / min). The results showed that the tannic acid was completely oxidized and decomposed, leaving only a small amount of white ash, and no carbon material was generated.

[0028] Compared with Example 1, Comparative Example 2 involves a programmed temperature pyrolysis in step S2 under an argon atmosphere.

[0029] Experimental Example ① Structural Testing: The porous carbon materials prepared in Examples 1-8 were scanned by electron microscopy, as shown in Figures 1-2; the elemental distribution diagrams of the porous carbon materials prepared in Examples 1-4 are shown in Figure 3.

[0030] ② Performance Testing: The porous carbon prepared in Example 1 has a specific surface area of ​​290.2 m² / g. Figure 4 shows the reflectance loss curve. The figure shows that the minimum reflection loss of the porous carbon material is -77.7 dB, and the effective absorption bandwidth reaches 7.68 GHz. In contrast, the porous carbon prepared in Comparative Example 2 has a specific surface area of ​​only 168.5 m² / g, a minimum reflection loss (RLmin) of -42.3 dB, and an effective absorption bandwidth (EAB) of 4.12 GHz.

[0031] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. A method for preparing a biomass-based porous carbon material, characterized in that, Includes the following steps: S1: Dissolve a phosphorus source and a carbon source in a solvent to obtain a mixed solution, and dry the mixed solution until the solvent is completely evaporated to obtain a pyrolysis precursor; the phosphorus source is selected from one or more of phytic acid, triphenylphosphine, phosphoric acid and polyphosphoric acid; the carbon source is selected from one or more of tannic acid, glucose, xylose, gelatin, ammonium alginate, chitosan and lignin; S2 The pyrolysis precursor is obtained by subjecting it to programmed temperature pyrolysis in an air atmosphere. The programmed temperature pyrolysis process includes: heating at a rate of 5~6℃ / min to 700℃, and then holding at that temperature for 1 hour.

2. The method for preparing biomass-based porous carbon materials according to claim 1, characterized in that, The solvent mentioned in step S1 is deionized water or ethanol, and the ratio of phosphorus source, carbon source and solvent is 0.4~0.6g:4~6g:60mL.

3. The method for preparing biomass-based porous carbon materials according to claim 1, characterized in that, The drying temperature in step S1 is 55~65℃.

4. A biomass-based porous carbon material, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 3.

5. The application of the biomass-based porous carbon material according to claim 4, characterized in that: The biomass-based porous carbon material can be used for electromagnetic wave shielding and absorption, adsorption of water pollutants, gas separation, or as a catalyst carrier.

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