Abandoned wind turbine blade-based porous carbon as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of solid waste recycling and porous carbon material synthesis, and particularly relates to abandoned wind turbine blade-based porous carbon as well as a preparation method and application thereof. The method comprises the following steps: carbonizing waste wind turbine blade powder in first protective gas, etching, mixing the obtained primary porous carbon material with an activator, and carrying out pyrolysis activation in second protective gas to obtain the waste wind turbine blade-based porous carbon. According to the method, the waste wind turbine blade is converted into the graded porous carbon material with micropores, mesopores and macropores, the diffusion performance of gas in the pore channels is greatly improved through the synergistic effect of the graded porous structure, the performance advantages of high capacity, fast mass transfer and high adaptability are shown, a way is provided for high-value recycling of the waste blade, and the method is suitable for industrial production. And a low-cost material is provided for the fields of energy storage and conversion, environmental governance, catalysis, adsorption and separation and the like, and the material has remarkable economic and environmental benefits and a wide commercial prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource utilization and porous carbon material synthesis, and particularly relates to a waste wind turbine blade-based porous carbon and a preparation method and application thereof. Background Art

[0002] With the rapid development of wind power generation, turbine blades made of glass fiber / carbon fiber reinforced composites (CFRPs) are being replaced in large numbers, becoming waste. Currently, the main disposal options for discarded turbine blades include landfill, mechanical recycling, thermochemical recycling, solvent decomposition, and innovative reuse. However, these methods face multiple technical, economic, and environmental bottlenecks. Landfilling, due to the non-degradability of CFRPs, poses risks of microplastic pollution, land occupation, and long-term environmental hazards. Mechanical recycling, through physical crushing, converts blades into building material aggregates, but significantly reduces the performance of the recycled material, and resin residues can easily lead to contamination in downstream applications, making its economic value limited. While thermochemical recycling can recover some fiber, it is energy-intensive, emits significant carbon emissions, and loses over 30% of fiber strength. Solvent decomposition, which dissolves the resin at low temperatures to preserve fiber properties, is hampered by the environmental risks and high costs of highly corrosive solvents, which restrict its widespread application. Innovative reuse (such as in bridges or public infrastructure) can extend the life of the material, but is limited by engineering compatibility challenges caused by the large size and complex curvature of the blades, and fragmented market demand makes it difficult to scale up. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a waste wind turbine blade-based porous carbon and its preparation method and application. The present invention uses waste wind turbine blades to prepare porous carbon with a multi-level pore structure and high strength, thereby realizing "high-value directional conversion of non-carbon fiber-based composite waste."

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] The present invention provides a method for preparing porous carbon based on discarded wind turbine blades, comprising the following steps:

[0006] Carbonizing powder of discarded wind turbine blades in a first protective gas, and etching the obtained carbonized material to obtain a primary porous carbon material;

[0007] The primary porous carbon material and an activator are mixed, and pyrolysis activation is performed in a second protective gas to obtain waste wind turbine blade-based porous carbon.

[0008] Preferably, the etching solution used in the etching is HF solution; the concentration of the HF solution is 3-20 wt%.

[0009] Preferably, the activator includes KOH solution, KOH powder, NaOH powder, NaOH solution, ZnCl2 solution, H3PO4 solution, water vapor or CO2 gas.

[0010] Preferably, when the activator is a KOH solution or a NaOH solution, the mass ratio of KOH to the primary porous carbon material in the KOH solution or the mass ratio of NaOH to the primary porous carbon material in the NaOH solution is independently 1 to 4:1; the primary porous carbon material and the activator are mixed so as to immerse the primary porous carbon material in a KOH solution or a NaOH solution; the immersion time is 6 to 12 hours; the temperature of the pyrolysis activation is 600 to 900°C, and the holding time is 0.5 to 3 hours.

[0011] Preferably, when the activator is an H3PO4 solution, the mass ratio of the volume of the H3PO4 solution to the primary porous carbon material is (2-5) mL:1 g; the concentration of the H3PO4 solution is 40-85 wt%; the primary porous carbon material and the activator are mixed so as to immerse the primary porous carbon material in the H3PO4 solution; the immersion time is 6-24 h; the temperature of the pyrolysis activation is 400-700°C, and the insulation time is 0.5-3 h.

[0012] Preferably, when the activator is a ZnCl2 solution, the mass ratio of ZnCl2 to the primary porous carbon material in the ZnCl2 solution is 1 to 3:1; the primary porous carbon material and the activator are mixed so as to immerse the primary porous carbon material in the ZnCl2 solution; the immersion time is 6 to 24 hours; the temperature of the pyrolysis activation is 400 to 800°C, and the insulation time is 1 to 4 hours.

[0013] Preferably, when the activating agent is CO2 gas, the flow rate of the CO2 gas is 50 to 300 mL / min; the temperature of the pyrolysis activation is 800 to 1000°C, and the holding time is 0.5 to 4 hours.

[0014] Preferably, when the activator is water vapor, the temperature of the pyrolysis activation is 800-1000°C, and the holding time is 0.5-3.0h; the activator is introduced in the form of a mixture of water vapor and a carrier gas; the flow rate of the water vapor is 0.4-2.0L / min; the total flow rate of the mixture of water vapor and carrier gas is 3-10L / min; the partial pressure of water vapor in the mixture of water vapor and carrier gas is 10-30vol%.

[0015] The present invention also provides a waste wind turbine blade-based porous carbon prepared by the preparation method described in the above technical solution, wherein the waste wind turbine blade-based porous carbon includes a silicon-oxygen skeleton and a porous carbon structure constructed on the silicon-oxygen skeleton through Si-OC interface bonding; it has a multi-level microporous structure, and the multi-level microporous structure includes a microporous structure, an ordered mesoporous structure and a macroporous structure; the pore diameter of the microporous structure is 1 to 3 nm; the pore diameter of the ordered mesoporous structure is 5 to 10 nm; and the pore diameter of the macroporous structure is 20 to 30 nm.

[0016] The present invention also provides the use of the discarded wind turbine blade-based porous carbon described in the above technical solution in energy storage and conversion, environmental governance, catalysis or adsorption and separation.

[0017] The present invention provides a method for preparing porous carbon based on discarded wind turbine blades, comprising the following steps: carbonizing powder of discarded wind turbine blades in a first protective gas, etching the obtained carbonized material to obtain a primary porous carbon material; mixing the primary porous carbon material with an activator, and performing pyrolysis activation in a second protective gas to obtain the discarded wind turbine blade-based porous carbon.

[0018] The present invention uses discarded wind turbine blades as raw materials to prepare porous carbon materials, breaking through the dual limitations of traditional waste recycling technology and porous material design. Its core innovation lies in the "high-value directional conversion of non-carbon fiber-based composite waste." Compared with existing biomass or plastic-based porous materials, the present invention achieves three major breakthroughs by precisely controlling the pyrolysis-reconstruction behavior of the glass fiber-thermosetting resin interface: First, the heterogeneous components synergistically enhance the efficiency, the thermosetting resin carbonizes to generate amorphous carbon, and the glass fiber partially melts at high temperature to form a silicon-oxygen skeleton, which not only inhibits the shrinkage of the carbon skeleton, but also constructs a rigid and flexible composite structure through Si-OC interface bonding, overcoming the difficult problem of strength-porosity inversion of porous materials; second, in-situ pore hierarchical regulation, utilizing the acidic etching properties of glass fiber and inducing the generation of a micro-meso-macroporous hierarchical system during the activation process of the activator, the diffusion efficiency of gas in the pores is greatly improved compared with traditional activated carbon; third, pollution reduction and carbon reduction throughout the entire life cycle, through the component complementarity of glass fiber and thermosetting resin, the glass fiber dust that is difficult to handle in traditional incineration processes is converted into a functional silicon-carbon composite, realizing the reconstruction from "environmental burden" to "performance carrier". BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a scanning electron microscope (SEM) image of the discarded wind turbine blade-based porous carbon prepared in Example 1;

[0020] Figure 2 The adsorption isotherms of CO2 and the Sips model fitting results of the discarded wind turbine blade-based porous carbon prepared in Examples 1 to 4 are shown;

[0021] Figure 3 This is a graph showing the adsorption capacity test results of the discarded wind turbine blade-based porous carbon prepared in Examples 1 and 2 for different sulfides;

[0022] Figure 4 The graph shows the adsorption capacity test results of the discarded wind turbine blade-based porous carbon prepared in Examples 1 and 2 for different olefins;

[0023] Figure 5 This is a graph showing the test results of the static saturated adsorption capacity of different VOCs by the discarded wind turbine blade-based porous carbon prepared in Example 2. DETAILED DESCRIPTION

[0024] The present invention provides a method for preparing porous carbon based on discarded wind turbine blades, comprising the following steps:

[0025] Carbonizing powder of discarded wind turbine blades in a first protective gas, and etching the obtained carbonized material to obtain a primary porous carbon material;

[0026] The primary porous carbon material and an activator are mixed, and pyrolysis activation is performed in a second protective gas to obtain waste wind turbine blade-based porous carbon.

[0027] Unless otherwise specified, the present invention has no special requirements on the sources of the raw materials used, and commercially available products known to those skilled in the art can be used.

[0028] The present invention carbonizes the powder of discarded wind turbine blades in a first protective gas to obtain a carbonized material.

[0029] As an embodiment, the discarded wind turbine blades are composited from glass fiber, thermosetting resin, core material and auxiliary materials. Thermosetting resin is usually used as a matrix material, accounting for 20-35% by mass. Glass fiber is used as a reinforcing element, accounting for 50-70% by mass. The core material includes balsa wood, polyvinyl chloride foam and adhesive, accounting for 5-15% by mass. The auxiliary materials are metal connectors, adhesives and coatings, accounting for 5-15% by mass.

[0030] Thermosetting resin serves as a carbon source and begins to pyrolyze to generate amorphous carbon at temperatures above 300°C. Glass fiber serves as a porous skeleton template and partially melts at high temperatures to form a silicon-oxygen skeleton to guide pore formation, thereby achieving synergistic utilization of thermosetting resin and glass fiber.

[0031] As an embodiment, the powder of the waste wind turbine blades is obtained by pre-treatment of the waste wind turbine blades; the pre-treatment includes sequentially performing a first washing, crushing, screening, acid leaching, a second washing and drying; the first washing is sequentially performing a water washing and an alcohol washing; the reagent used for the water washing is distilled water; the reagent used for the alcohol washing is ethanol; the crushing is sequentially performing segmentation and grinding; the segmentation is cutting into small segments of 3 to 5 cm; the equipment used for grinding is a solid phase shear grinder; the mesh number of the sieve used for the screening is 50 to 300 mesh, and in the specific embodiment, it is 50 mesh, 100 mesh, 150 mesh, 200 mesh, 250 mesh or 300 mesh; the reagent used for acid leaching is hydrochloric acid solution; the concentration of the hydrochloric acid solution is 5-30wt%, and in specific embodiments, it is 5wt%, 10wt%, 15wt%, 20wt%, 25wt% or 30wt%; the ratio of the mass of the waste wind turbine blades after screening to the volume of the hydrochloric acid solution is 1g:(10-30)mL, and in specific embodiments, it is 1g:10mL, 1g:15mL, 1g:20mL, 1g:25mL or 1g:30mL; the time of the acid leaching is 2-8h, and in specific embodiments, it is 2h, 3h, 4h, 5h, 6h, 7h or 8h; the acid leaching process is supplemented by ultrasonic treatment; the power of the ultrasonic treatment is 1000-2000W, and in specific embodiments, it is 1000W, 1100W, 1200W, 1300W, 1400W, 1500W, 1600W, 1700W, 1800W, 1900W or 2000W; the frequency of the ultrasonic treatment is 0.5-1.5MHz, and in specific embodiments, it is 0.5MHz, 0.6MHz, 0.7MHz, 0.8MHz, 0.9MHz, 1.0MHz, 1.1MHz, 1.2MHz Hz, 1.3MHz, 1.4MHz or 1.5MHz; the ultrasonic treatment time is 10 to 30 minutes, and in specific embodiments, it is 10 minutes, 12 minutes, 14 minutes, 16 minutes, 18 minutes, 22 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes or 30 minutes; the reagent used in the second washing is distilled water; the second washing is performed until the waste wind turbine blades after the acid leaching are neutral; the drying temperature is 80 to 100°C, and in specific embodiments, it is 90°C, and the drying time is 8 to 12 hours, and in specific embodiments, it is 10 hours.

[0032] The present invention removes metal impurities from discarded wind turbine blades through acid leaching. Using a hydrochloric acid solution within the aforementioned concentration range prevents both the poor metal dissolution effect of low-concentration acid and the excessive corrosion of the carbon skeleton prepared from discarded wind turbine blades caused by high-concentration acid, which could lead to pore structure collapse or uneven pore size distribution, reducing the specific surface area and porosity of the carbon material and weakening its adsorption properties.

[0033] As an embodiment, the first protective gas is nitrogen; the carbonization temperature is 600-1000°C, specifically 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C; the holding time is 2-5h, specifically 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h; the heating rate to the carbonization temperature is 5-15°C / min, specifically 5°C / min, 7°C / min, 9°C / min, 11°C / min, 13°C / min or 15°C / min.

[0034] The present invention adopts a carbonization temperature within the above range. When the carbonization temperature exceeds 1000°C, the carbon skeleton is excessively graphitized, reducing active sites and inducing pore collapse, resulting in uneven pore size distribution and even the formation of closed pores, which hinders material transfer, reduces the specific surface area and porosity of the carbonized material, and weakens its adsorption capacity. If the carbonization temperature is too low, the powder of discarded wind turbine blades will not be fully pyrolyzed, and the organic volatiles and impurities inside cannot be effectively removed. The residues will not only block the initial pore channels but also form chemically unstable defect sites in the carbon skeleton. At the same time, the migration and recombination of carbon atoms under low temperature conditions are inhibited, making it difficult to form a continuous and highly crystalline carbon skeleton network structure, resulting in a significant weakening of the mechanical strength of the carbonized material. In addition, due to insufficient thermodynamic driving force, the surface functional groups are disordered and aggregated or partially missing, further leading to a chain reaction of hindered pore development, reduced specific surface area, and deteriorated chemical stability, ultimately limiting the functional expression of the discarded wind turbine blade-based porous carbon.

[0035] The present invention adopts a carbonization time within the above range. When the holding time is less than 2 hours, the pyrolysis kinetics of the powdered waste wind turbine blades are limited, and the residual undecomposed organic matter and disordered carbon fragments will block the pore channels and introduce structural defects, resulting in the obstruction of pore network development and the discretization of pore size distribution. When the holding time is longer than 5 hours, the carbon skeleton is over-pyrolyzed. On the one hand, the continuous growth of graphite microcrystals leads to the collapse of pore walls and the imbalance of the proportion of pore structures of different sizes. On the other hand, at high temperatures, the surface oxygen-containing functional groups undergo selective decomposition due to differences in thermal stability, resulting in a decrease in active site density and surface chemical inertness. These two factors synergistically weaken the adsorption performance of the porous carbon based on waste wind turbine blades.

[0036] After obtaining the carbonized material, the present invention etches the carbonized material to obtain a primary porous carbon material.

[0037] As an embodiment, the etching solution used in the etching is an HF solution; the concentration of the HF solution is 3-20wt%, and in specific embodiments, it is 3wt%, 5wt%, 7wt%, 9wt%, 11wt%, 13wt%, 15wt%, 17wt%, 19wt% or 20wt%; the etching time is 2-20h, and in specific embodiments, it is 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h or 20h; the etching is: The carbonized material is soaked in the etching liquid; after the etching, it also includes: separating the etched mixed material into solid and liquid, and washing and drying the obtained solid in turn to obtain a primary porous carbon material; the solid-liquid separation is filtration; the reagent used for the washing is distilled water; the number of washings is 5 to 8 times, and in a specific embodiment, it is 5 times or 8 times; the washing is to a neutral level; the drying temperature is 80 to 100°C, and in a specific embodiment, it is 90°C, and the time is 8 to 12 hours, and in a specific embodiment, it is 10 hours.

[0038] The present invention employs an HF solution concentration within the above-mentioned range. When the HF solution concentration is too high, its strong etching properties accelerate the dissolution kinetics of the silicon-based template formed by the glass fiber, causing the silicon-based template to disintegrate prematurely and fail to effectively guide the in-situ pore formation process, resulting in pore wall collapse and disordered multi-level pore topology. When the concentration is too low, insufficient etching driving force makes it difficult to fully remove the silicon-based template, forming a physical barrier between unreacted silicon-based template fragments and the carbon matrix, which not only inhibits the development of pore connectivity but also introduces impurity phases due to silicon residues, destroying the chemical uniformity of the material and exacerbating the discreteness of the pore size distribution.

[0039] After obtaining the primary porous carbon material, the present invention mixes the primary porous carbon material with an activator, and performs pyrolysis activation in a second protective gas to obtain waste wind turbine blade-based porous carbon.

[0040] As an embodiment, the activator includes KOH solution, KOH powder, NaOH powder, NaOH solution, ZnCl2 solution, H3PO4 solution, water vapor or CO2 gas.

[0041] When the activator is a KOH solution or a NaOH solution, the mass ratio of KOH to the primary porous carbon material in the KOH solution or the mass ratio of NaOH to the primary porous carbon material in the NaOH solution is independently 1 to 4:1, and in specific embodiments, it is 1:1, 2:1, 3:1 or 4:1; the primary porous carbon material and the activator are mixed so that the primary porous carbon material is immersed in a KOH solution or a NaOH solution; the immersion time is 6 to 12 hours, and in specific embodiments, it is 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours or 12 hours; the temperature of the pyrolysis activation is 600 to 900°C, and in specific embodiments, it is 600°C, 650°C, 700°C, 750°C, 800°C, 850°C or 900°C, and the holding time is 0.5 to 3 hours, and in specific embodiments, it is 1 hour, 1.5 hours, 2.0 hours, 2.5 hours or 3.0 hours.

[0042] When the activator is KOH powder or NaOH powder, the mass ratio of the KOH powder or NaOH powder to the primary porous carbon material is 1 to 4:1, and in specific embodiments, it is 1:1, 2:1, 3:1 or 4:1; the primary porous carbon material and the activator are mixed to mix the primary porous carbon material and KOH powder or NaOH powder; the temperature of the pyrolysis activation is 600 to 900°C, and in specific embodiments, it is 600°C, 650°C, 700°C, 750°C, 800°C, 850°C or 900°C, and the holding time is 1 to 3h, and in specific embodiments, it is 1h, 1.5h, 2.0h, 2.5h or 3.0h.

[0043] When the conditions of pyrolysis activation are lower than the range defined in the present invention, the pyrolysis activation reaction is insufficient, the primary porous carbon material is not effectively etched, the pores are insufficiently developed and the pore size distribution is uneven, the specific surface area is significantly reduced, and at the same time, the non-carbon components (such as ash) in the primary porous carbon material cannot be fully removed. When the pyrolysis activation conditions are within the numerical range defined in the present invention, the activation etching pore formation of the activator plays a major role, so both micropores and mesopores are improved. When the pyrolysis activation conditions exceed the upper limit of the range defined in the present invention, the excessive expansion of micropores and mesopores causes the pore wall to collapse or the pore connectivity to decrease, which in turn reduces the effective specific surface area and mechanical strength.

[0044] When the activator is a ZnCl2 solution, the mass ratio of ZnCl2 to the primary porous carbon material in the ZnCl2 solution is 1 to 3:1, and in specific embodiments is 1.0:1, 1.5:1, 2.0:1, 2.5:1 or 3.0:1; the primary porous carbon material and the activator are mixed to immerse the primary porous carbon material in the ZnCl2 solution; the immersion time is 6 to 24 hours, and in specific embodiments is 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h; the temperature of the pyrolysis activation is 400-800°C, specifically 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C or 800°C, and the holding time is 1-4h, specifically 1h, 1.5h, 2.0h, 2.5h or 3.0h.

[0045] When the pyrolysis activation conditions are lower than the specified range of the present invention, the orderly growth of the carbon layer is hindered due to insufficient catalysis, and the surface oxygen-containing functional groups remain excessively due to the hysteresis of the pyrolysis kinetics, inducing oxidation side reactions and weakening the chemical stability. At the same time, the low concentration of the activator will also lead to disordered etching paths, discrete pore size distribution and mainly macropores or non-through micropores, and a significant decrease in specific surface area. In addition, the uncarbonized organic matter and ash produced by incomplete pyrolysis of the primary porous carbon material are deposited in the pores, further hindering the permeability of the mass transfer channel. When the activation conditions exceed the upper limit of the specified range of the present invention, the carbon skeleton undergoes densification and shrinkage due to excessive dehydration and cross-linking, and even local brittle fracture, and the pore wall collapses, resulting in an imbalance in the mesopore-macropore ratio. The ZnO nanoparticles generated in situ at high temperature are difficult to be completely removed by conventional acid washing due to grain coarsening. Their agglomerates not only block the pores and introduce closed-pore structures, but also aggravate the surface chemical inertness due to residual ash, ultimately causing the specific surface area to drop sharply below the critical value.

[0046] When the activator is an H3PO4 solution, the mass ratio of the volume of the H3PO4 solution to the primary porous carbon material is (2-5) mL:1g, and in specific embodiments, it is 2.0 mL:1g, 2.5 mL:1g, 3.0 mL:1g, 3.5 mL:1g, 4.0 mL:1g, 4.5 mL:1g or 5.0 mL:1g; the concentration of the H3PO4 solution is 40-85 wt%, and in specific embodiments, it is 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt% or 85 wt%. wt%; the primary porous carbon material and the activator are mixed to immerse the primary porous carbon material in a H3PO4 solution; the immersion time is 6 to 24 hours, and in specific embodiments, it is 6 hours, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours or 24 hours; the pyrolysis activation temperature is 400 to 700°C, and in specific embodiments, it is 400°C, 450°C, 500°C, 550°C, 600°C, 650°C or 700°C, and the holding time is 0.5 to 3 hours, and in specific embodiments, it is 0.5 hours, 1 hour, 1.5 hours, 2.0 hours, 2.5 hours or 3.0 hours.

[0047] When the pyrolysis activation conditions are lower than the range defined in the present invention, the cross-linking reaction is insufficient, and the primary porous carbon material is prone to produce disordered carbon structure during pyrolysis, the pores are insufficiently developed, and the pore size distribution is mainly composed of non-connected macropores or underdeveloped micropores. The ash in the primary porous carbon material cannot be effectively removed, and the insufficient amount of phosphorus doping leads to surface chemical inertness, which limits its performance in the adsorption process. When the pyrolysis activation conditions exceed the upper limit of the range defined in the present invention, excessive acidification will cause the carbon skeleton to be excessively cross-linked and the structure to be loose, the mechanical strength will be significantly reduced, and the residual phosphate will decompose at high temperature to produce gas that destroys the pore structure, causing pore collapse. In addition, excessive phosphorus doping will also form inactive phosphate particles that block the pores and introduce too many acidic sites.

[0048] When the activating agent is CO2 gas, the flow rate of the CO2 gas is 50-300 mL / min, and in specific embodiments, it is 50 mL / min, 100 mL / min, 150 mL / min, 200 mL / min, 250 mL / min or 300 mL / min; the temperature of the pyrolysis activation is 800-1000°C, and in specific embodiments, it is 800°C, 850°C, 900°C, 950°C or 1000°C, and the holding time is 0.5-4h, and in specific embodiments, it is 0.5h, 1.0h, 1.5h, 2.0h, 2.5h, 3.0h, 3.5h or 4.0h.

[0049] When the pyrolysis activation conditions are lower than the specified range, the pyrolysis activation reaction is insufficient, the pore development is limited, the pore size distribution is mainly composed of non-connected closed pores or unetched dense carbon, and the ash in the primary porous carbon material cannot be effectively removed, resulting in low purity and poor mass transfer efficiency of the discarded wind turbine blade-based porous carbon. In addition, the CO2 activation efficiency drops sharply at low temperatures, the reaction kinetics are slow, and it is difficult to form a uniform pore network. When the pyrolysis activation conditions exceed the upper limit of the range specified by the present invention, the primary porous carbon material will be over-oxidized, resulting in excessive etching of the carbon skeleton, the collapse of the micropore walls and the merger of mesopores or macropores, reducing the effective specific surface area, and the abnormal increase in the degree of graphitization of the primary porous carbon material, reducing surface defect sites and functional groups, weakening its adsorption performance, and in extreme cases, excessive consumption of the carbon matrix and a significant decrease in mechanical strength.

[0050] When the activating agent is water vapor, the temperature of the pyrolysis activation is 800-1000°C, specifically 800°C, 850°C, 900°C, 950°C or 1000°C in specific embodiments, and the holding time is 0.5-3.0h, specifically 0.5h, 1.0h, 1.5h, 2.0h, 2.5h or 3.0h in specific embodiments; the activating agent is introduced in the form of a mixture of water vapor and carrier gas; the flow rate of the water vapor is 0.4-2.0L / min, specifically 0.4L / min, 0.8L / min in specific embodiments. in, 1.0 L / min, 1.2 L / min, 1.6 L / min or 2.0 L / min; the carrier gas is N2; the total flow rate of the mixture of water vapor and carrier gas is 3 to 10 L / min, and in specific embodiments, it is 3 L / min, 5 L / min or 7 L / min; the partial pressure of water vapor in the mixture of water vapor and carrier gas is 10 to 30 vol%, and in specific embodiments, it is 10 vol%, 14.3 vol%, 15 vol%, 20 vol%, 25 vol% or 30 vol%.

[0051] When the pyrolysis activation conditions are lower than the specified range of the present invention, only the surface of the primary porous carbon material is activated, the internal pores are not fully opened, and the pore development is restricted, resulting in a low specific surface area and uneven pore size distribution. When the pyrolysis activation conditions exceed the upper limit of the range specified in the present invention, the gasification reaction of the carbon skeleton will be aggravated, causing the micropores to merge or collapse, forming coarsened mesopores or even macropores, and may also cause local ablation of the carbon skeleton, reducing the mechanical strength of the primary porous carbon material and increasing the risk of ash clogging the pores.

[0052] When the activator is KOH solution or NaOH solution or ZnCl2 solution or H3PO4 solution, the impregnation is carried out under stirring conditions; the stirring temperature is room temperature; the stirring rate is 400-800rpm, and is 600rpm in a specific embodiment; after the impregnation, it also includes: drying the impregnated primary porous carbon material, and then pyrolyzing and activating the obtained activated mixture; the drying temperature is 80-100°C, and is 90°C in a specific embodiment; the time is 8-12h, and is 10h in a specific embodiment; the equipment used for the drying is an oven; the activated mixture is then pyrolyzed and activated as follows: the activated mixture is spread flat on a porcelain boat, the porcelain boat is placed in a tubular furnace, and the activated mixture is pyrolyzed and activated in a second protective gas.

[0053] As an embodiment, the second protective gas is nitrogen; when the activator is CO2 gas, after the pyrolysis activation is completed, the CO2 gas is switched back to the second protective gas for cooling.

[0054] As an embodiment, the heating rate for heating to the pyrolysis activation temperature is 3 to 15°C / min, and in specific embodiments it is 3°C / min, 5°C / min, 7°C / min, 9°C / min, 11°C / min, 13°C / min or 15°C / min.

[0055] The present invention uses different activators to pyrolyze and activate the primary porous carbon material, which can greatly increase the specific surface area of ​​the final discarded wind turbine blade-based porous carbon. At the same time, its pore structure can be adjusted, thereby increasing the practical application range of the discarded wind turbine blade-based porous carbon.

[0056] The KOH pyrolysis activation process is a multi-stage coordinated redox and intercalation etching process. At high temperature, KOH first melts and penetrates into the primary porous carbon material, achieving pore construction through the following reaction pathways:

[0057] (1) Oxidation etching: KOH reacts strongly with carbon, i.e., 6KOH+2C→2K+3H2↑+2K2CO3. The released H2 and generated K2CO3 further decompose, and the equation is K2CO3→K2O+CO2↑. The generated CO2 gas reacts with carbon, C+CO2→2CO↑, forming a microporous structure.

[0058] (2) Metal potassium intercalation: The generated metal potassium vapor is embedded in the carbon layers, causing lattice expansion and exfoliation of graphite crystals, resulting in mesopores and some macropores;

[0059] (3) Template effect: K2O and unreacted KOH form a nanoscale molten salt phase in the carbon matrix, which is removed by acid washing after cooling, leaving behind a hierarchical pore network. This process can precisely control the ratio of micropores to mesopores by adjusting the KOH / C mass ratio and the activation temperature, resulting in a porous carbon with a hierarchical pore structure based on discarded wind turbine blades.

[0060] The mechanism of action of NaOH in the chemical activation of porous carbon based on discarded wind turbine blades is a synergistic effect of multi-stage redox reactions and molten salt template effect. During the high-temperature activation stage, NaOH undergoes the following key processes:

[0061] (1) Melt infiltration: After melting, NaOH penetrates into the primary porous carbon material and undergoes an oxidative etching reaction with amorphous carbon. The equation is: 6NaOH+2C→2Na+3H2↑+2Na2CO3. The released H2 and the generated Na2CO3 further decompose into Na2CO3→Na2O+CO2↑. The generated CO2 reacts with carbon, i.e., C+CO2→2CO↑, forming micropores.

[0062] (2) Sodium vapor intercalation: The metallic sodium generated by the reaction is embedded in the carbon interlayer in the form of vapor, causing the carbon skeleton to expand and the graphite crystals to partially peel off, resulting in a mesoporous structure;

[0063] (3) Molten salt template effect: Unreacted NaOH and generated Na2O form a dynamic molten salt network, acting as a "soft template" in the carbon matrix. After cooling, it is removed by acid washing to form a through-hole macroporous-mesoporous channel. Compared with KOH, the lower reactivity of NaOH leads to a slower etching rate, but the smaller atomic radius of sodium ions makes it easier to penetrate deep into the carbon layer, forming a more uniform micropore distribution. By adjusting the NaOH / C mass ratio and activation temperature, porous carbon based on discarded wind turbine blades with mainly micropores can be obtained.

[0064] The mechanism of action of ZnCl2 in the chemical activation of porous carbon derived from discarded wind turbine blades is primarily based on its catalytic dehydration, crosslinking stabilization, and high-temperature template effect as a Lewis acid. During the activation process, ZnCl2 regulates pore formation through the following multi-stage pathway:

[0065] (1) Low-temperature dehydration and aromatization: ZnCl2 penetrates into the interior of the primary porous carbon material after low-temperature melting. Its strong water absorption promotes the dehydration of the primary porous carbon material and catalyzes the aromatic ring condensation reaction to form a rigid cross-linked structure, which inhibits the volume shrinkage during the carbonization process and thus retains the initial pore framework;

[0066] (2) Molten salt template effect: At high temperature, ZnCl2 partially reacts with carbon, the equation is: ZnCl2+C→Zn+2HCl↑, the generated HCl gas etches the carbon layer to form micropores, and at the same time, the unreacted ZnCl2 and by-products are distributed in the carbon matrix in a molten state. After cooling, they are removed by acid washing to form through-hole channels mainly composed of mesopores;

[0067] (3) Graphite crystallite regulation: The catalytic effect of ZnCl2 promotes the graphitization tendency of the carbon precursor, forming a locally ordered graphene-like layer structure. Unlike the high-temperature strong oxidative etching of KOH / NaOH, ZnCl2 activation relies more on mild physical templates and catalytic cross-linking, so the resulting porous carbon is mainly mesoporous.

[0068] The mechanism of action of H3PO4 in the chemical activation of porous carbon based on discarded wind turbine blades is mainly based on its catalytic dehydration, cross-linking stabilization and phosphate template effect as a Lewis acid. The specific process can be divided into two stages: low-temperature cross-linking and high-temperature pore formation. In the low-temperature carbonization stage, H3PO4 forms phosphate bonds with the hydroxyl groups of the primary porous carbon material through protonation, catalyzing dehydration and aromatization reactions to form a cross-linked rigid carbon skeleton, inhibiting thermal decomposition shrinkage and retaining the initial pores; in the high-temperature activation stage, H3PO4 further decomposes to form polyphosphates and pyrophosphates, which form pores through the following pathways: (1) the phosphate melt infiltrates the carbon matrix, inhibiting the growth of graphite microcrystals and forming micropores between disordered carbon layers; (2) the phosphate reacts with carbon under high temperature to partially oxidize, releasing gas to etch pores; (3) the residual phosphate is removed by water after cooling, forming a through-hole network dominated by mesopores. In addition, the acidic environment of H3PO4 promotes the formation of surface oxygen-containing functional groups and enhances the adsorption capacity of polar molecules. By adjusting the H₃PO₄ / primary porous carbon material impregnation ratio and activation temperature, the specific surface area and mesopore fraction of porous carbon derived from discarded wind turbine blades can be controlled. Compared to KOH or ZnCl₂, H₃PO₄ activation relies more on the synergy of low-temperature crosslinking protection and high-temperature template pore formation, and the surface chemical properties of the product are more easily controlled.

[0069] The mechanism of CO2 activation in porous carbon based on discarded wind turbine blades is based on its selective gasification reaction as a weak oxidizing gas, and the directional control of the pore structure is achieved through heterogeneous oxidation etching with the carbon matrix at high temperature. During the activation process, CO2 molecules diffuse to the surface and interior of the carbon skeleton, and preferentially react with the amorphous carbon in the primary porous carbon material to form C+CO2→2CO↑. This reaction creates pores through the following multi-scale mechanism:

[0070] (1) Micropore formation: The preferential oxidation removal of amorphous carbon regions forms initial micropores, whose pore size distribution is precisely controlled by the activation temperature and time. High temperature promotes the merging of micropores to form mesopores.

[0071] (2) Pore wall modification: CO2 reacts with active sites at the edges of graphite crystallites, expanding the interlayer spacing and exposing more adsorption sites;

[0072] (3) Gas flushing effect: The generated CO gas flushes the inner wall of the pores as it escapes, reducing pore blockage and enhancing pore connectivity. Compared with the aforementioned chemical activators, CO2 activation avoids chemical residues, but the reaction kinetics are slower and higher temperatures are required to overcome the activation energy barrier. By regulating the CO2 flow rate and activation time, the micropore / mesopore ratio can be optimized. The resulting porous carbon based on discarded wind turbine blades has fewer oxygen-containing functional groups on the surface, making it suitable for applications requiring high chemical stability.

[0073] The mechanism for preparing porous carbon derived from discarded wind turbine blades by water vapor activation is essentially a selective oxidation reaction between the carbon matrix and the gaseous activator, water vapor, at high temperatures. This synergistic effect of vaporization etching and directional pore control leads to the formation of a porous structure. At high temperatures, water vapor molecules undergo a redox reaction with active sites on the carbon surface, i.e., C + H₂O → CO↑ + H₂↑. This endothermic reaction preferentially etches disordered regions or weakly bonded carbon atoms within the carbon framework, releasing CO and H₂ gases. During the gas evolution process, diffusion channels are formed within the carbon matrix, further promoting the development of micropores and mesopores. During this process, the layer-by-layer etching of the carbon layers by water vapor molecules not only expands the pore volume through the evolution of topological defects but also, because the reaction kinetics are controlled by the temperature gradient and vapor partial pressure, allows for the control of pore size distribution. Furthermore, oxygen atoms in the water vapor may remain on the carbon surface in the form of carbonyl groups, imparting hydrophilicity or catalytically active sites. Ultimately, porous carbon derived from discarded wind turbine blades exhibits a high specific surface area, hierarchical porosity, and surface functionalization.

[0074] As an embodiment, after the pyrolysis activation, it also includes: cooling the product obtained by the pyrolysis activation, washing and drying in sequence to obtain a discarded wind turbine blade-based porous carbon; the cooling is cooling to room temperature with the furnace; the washing is acid washing and water washing in sequence; the reagent used for the acid washing is a hydrochloric acid solution; the concentration of the hydrochloric acid solution is 4 to 16 wt%, and in the specific embodiment, it is 4 wt%, 6 wt%, 8 wt%, 10 wt%, 12 wt%, 14 wt% or 16 wt%; the number of acid washings is 3 to 8 times, and in the specific embodiment, it is 5 times; the reagent used for the water washing is deionized water; the water washing is repeatedly rinsing the product obtained by the pyrolysis activation after the acid washing with deionized water until it is neutral; the drying temperature is 80 to 100 ° C, and in the specific embodiment, it is 90 ° C; the time is 8 to 12 h, and in the specific embodiment, it is 10 h.

[0075] The present invention adopts a two-stage calcination process of carbonization-pyrolysis activation to prepare porous carbon based on discarded wind turbine blades. First, the thermosetting resin and some auxiliary materials in the discarded wind turbine blade raw materials are removed by high-temperature carbonization to obtain a primary porous carbon material with a stable carbon content; then, the primary porous carbon material is evenly mixed with an activator and then pyrolyzed and activated. While eliminating the remaining small amount of volatile matter, the activator and the primary porous carbon material undergo a chemical reaction at high temperature, etching holes on the surface of the primary porous carbon material to further enrich the pore structure of the discarded wind turbine blade-based porous carbon and provide more gas transmission channels. Therefore, the discarded wind turbine blade-based porous carbon prepared by the present invention is expected to show obvious advantages in practical applications.

[0076] The present invention also provides a waste wind turbine blade-based porous carbon prepared by the preparation method described in the above technical solution; the waste wind turbine blade-based porous carbon includes a silicon-oxygen skeleton and a porous carbon structure constructed on the silicon-oxygen skeleton through Si-OC interface bonding; it has a multi-level microporous structure, and the multi-level microporous structure includes a microporous structure, an ordered mesoporous structure and a macroporous structure; the pore diameter of the microporous structure is 1 to 3 nm; the pore diameter of the ordered mesoporous structure is 5 to 10 nm; and the pore diameter of the macroporous structure is 20 to 30 nm.

[0077] The three-dimensional interconnected network of micropores, ordered mesopores, and macropores in this invention enables the discarded wind turbine blade-based porous carbon to exhibit advantages in different pore sizes and a synergistic effect of multi-level pore sizes during adsorption. The proportions of each level of pore structure in the discarded wind turbine blade-based porous carbon prepared under different activation conditions vary.

[0078] The present invention also provides the use of the discarded wind turbine blade-based porous carbon described in the above technical solution in energy storage and conversion, environmental governance, catalysis or adsorption and separation.

[0079] The present invention does not specifically limit the application of the discarded wind turbine blade-based porous carbon in energy storage and conversion, environmental management, catalysis, or adsorption and separation, and any application method well known in the art may be used.

[0080] The technical solutions of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention, but they should not be understood as limiting the scope of protection of the present invention.

[0081] Example 1

[0082] The preparation method of the porous carbon based on discarded wind turbine blades is as follows:

[0083] (1) Waste wind turbine blades were washed with distilled water and ethanol in sequence and cut into 3-5 cm segments. The segments were then pulverized in a solid phase shear mill and passed through a 50-mesh sieve to obtain a raw material powder. 5 g of the raw material powder was soaked in 50 mL of a 5 wt% HCl solution for 2 h. During the soaking process, the raw material powder was ultrasonically treated for 10 min at an ultrasonic power of 1000 W and an ultrasonic frequency of 0.5 MHz. The acid-soaked raw material powder was then washed with distilled water until neutral and dried in an oven at 100° C. for 10 h to obtain a pretreated raw material powder.

[0084] (2) heating the pretreated raw material powder to 600°C at a heating rate of 5°C / min and keeping the temperature for 2 hours. After the heat preservation is completed, the raw material powder is cooled to room temperature with the furnace to complete high-temperature carbonization to obtain a carbonized material; then, the carbonized material is immersed in a 3wt% HF solution, immersed for 2 hours and filtered, and the obtained solid is washed 8 times with distilled water until neutral, and then dried at 90°C for 10 hours to obtain a primary porous carbon material;

[0085] (3) Weigh the corresponding mass of the primary porous carbon material and KOH solid according to a mass ratio of 1:1, and put the KOH solid into a beaker and add distilled water to prepare a KOH solution with a concentration of 7 mol / L, put the weighed primary porous carbon material into the KOH solution, stir it at 600 rpm at room temperature for 6 hours, and then place it in a 90°C oven for drying for 10 hours to obtain an activated mixture; spread the activated mixture flat on a porcelain boat, place the porcelain boat in a flat tube furnace, and perform pyrolysis activation on the activated mixture under a nitrogen atmosphere, heat the activated mixture to 600°C at a heating rate of 3°C / min and keep it warm for 0.5 hours, cool it to room temperature with the furnace after the insulation is completed, and complete the pyrolysis activation. After the pyrolysis activation is completed, wash the product obtained by pyrolysis activation with 4 wt% HCl solution 5 times, then repeatedly rinse the activated product with deionized water until it is neutral, and dry it at 90°C for 10 hours to obtain a discarded wind turbine blade-based porous carbon.

[0086] Example 2

[0087] The preparation method of the porous carbon based on discarded wind turbine blades is as follows:

[0088] (1) Waste wind turbine blades were washed with distilled water and ethanol in sequence and cut into small segments of 3 to 5 cm. The blades were then pulverized in a solid phase shear mill and passed through a 200-mesh sieve to obtain a raw material powder. 5 g of the raw material powder was soaked in 100 mL of a 5 wt% HCl solution for 5 h. During the soaking process, the raw material powder was ultrasonically treated for 20 min at an ultrasonic power of 1500 W and an ultrasonic frequency of 1.0 MHz. The acid-soaked raw material powder was then washed with distilled water until neutral and dried in an oven at 100° C. for 10 h to obtain a pretreated raw material powder.

[0089] (2) heating the pretreated raw material powder to 800°C at a heating rate of 8°C / min and keeping the temperature for 3 hours. After the end of the heat preservation, the raw material powder is cooled to room temperature with the furnace to complete high-temperature carbonization to obtain a carbonized material; then, the carbonized material is immersed in a 7wt% HF solution, immersed for 4 hours and then filtered. The obtained solid is washed with distilled water 5 times until neutral, and then dried at 90°C for 10 hours to obtain a primary porous carbon material;

[0090] (3) Weigh the corresponding masses of the primary porous carbon material and KOH solid according to a mass ratio of 1:3, and put the KOH solid into a beaker and add distilled water to prepare a KOH solution with a concentration of 7 mol / L, put the weighed primary porous carbon material into the KOH solution, stir at 600 rpm at room temperature for 8 hours, and then place it in a 90°C oven for drying for 10 hours to obtain an activated mixture; spread the activated mixture flat on a porcelain boat, place the porcelain boat in a flat tube furnace, and perform pyrolysis activation on the activated mixture under a nitrogen atmosphere, heat the activated mixture to 800°C at a heating rate of 7°C / min and keep it warm for 90 minutes, cool it to room temperature with the furnace after the insulation is completed, and complete the pyrolysis activation. After the pyrolysis activation is completed, the product obtained by pyrolysis activation is washed 5 times with 6 wt% HCl solution, and then repeatedly rinsed with deionized water until the activated product is neutral, and dried at 90°C for 10 hours to obtain a discarded wind turbine blade-based porous carbon.

[0091] Example 3

[0092] The difference from Example 1 is that the KOH solution is replaced by a NaOH solution.

[0093] Example 4

[0094] The difference from Example 2 is that the KOH solution is replaced by a NaOH solution.

[0095] Example 5

[0096] The difference from Example 1 is that the KOH solution is replaced by KOH powder.

[0097] Example 6

[0098] The difference from Example 2 is that the KOH solution is replaced by KOH powder.

[0099] Example 7

[0100] The difference from Example 1 is that the KOH solution is replaced by a ZnCl2 solution, the pyrolysis activation temperature is replaced by 400°C, and the pyrolysis activation time is replaced by 1 h.

[0101] Example 8

[0102] The difference from Example 2 is that the KOH solution is replaced by a ZnCl2 solution.

[0103] Example 9

[0104] The difference from Example 1 is that the activator KOH is replaced by H3PO4 solution, and the pyrolysis activation conditions are replaced as follows: the ratio of the volume of the activator to the mass of the primary carbon material is 2mL:1g, the concentration of the H3PO4 solution is 40wt%, the immersion time is 6h, the pyrolysis activation temperature is 400℃, and the pyrolysis activation time is 0.5h.

[0105] Example 10

[0106] The difference from Example 2 is that the activator KOH is replaced by H3PO4 solution, and the pyrolysis activation conditions are replaced as follows: the ratio of the volume of the activator to the mass of the primary carbon material is 4mL:1g, the concentration of the H3PO4 solution is 60wt%, the immersion time is 10h, the pyrolysis activation temperature is 600℃, and the pyrolysis activation time is 2h.

[0107] Example 11

[0108] The difference from Example 1 is that the activator KOH solution is replaced by CO2 gas, and the pyrolysis activation conditions are replaced as follows: the CO2 gas flow rate is 50 mL / min, the pyrolysis activation temperature is 800°C, the pyrolysis activation time is 0.5 h, and after the pyrolysis activation is completed, it is switched back to nitrogen and cooled to room temperature.

[0109] Example 12

[0110] The difference from Example 2 is that the activator KOH solution is replaced by CO2 gas, and the pyrolysis activation conditions are replaced as follows: the CO2 gas flow rate is 100 mL / min, the pyrolysis activation temperature is 900°C, the pyrolysis activation time is 2.5 h, and after the pyrolysis activation is completed, it is switched back to nitrogen and cooled to room temperature.

[0111] Example 13

[0112] The difference from Example 1 is that the activator KOH solution is replaced by water vapor, and the pyrolysis activation conditions are replaced as follows: the pyrolysis activation temperature is 800°C, the pyrolysis activation time is 0.5h, and the water vapor is introduced in the form of a mixture of water vapor and N2, the water vapor flow rate is 0.4L / min (total mixed flow rate is 3L / min), and the partial pressure of water vapor in the mixed gas is 10vol%.

[0113] Example 14

[0114] The difference from Example 2 is that the activator KOH solution is replaced by water vapor, and the pyrolysis activation conditions are replaced as follows: the pyrolysis activation temperature is 900°C, the pyrolysis activation time is 2 h, water vapor is introduced in the form of a mixture of water vapor and N2, the water vapor flow rate is 1.0 L / min (total flow rate of the mixed gas is 7 L / min), and the partial pressure of water vapor in the mixed gas is 14.3 vol%.

[0115] Comparative Example 1

[0116] The difference from Example 1 is that the carbonized material obtained in step (2) is not etched in HF solution.

[0117] Comparative Example 2

[0118] The difference from Example 3 is that step (3) is deleted, that is, the primary porous carbon material obtained in step (2) is not activated with NaOH.

[0119] Performance Testing

[0120] (1) Figure 1 This is a scanning electron microscope image of the discarded wind turbine blade-based porous carbon prepared in Example 1. Figure 1 It can be seen from the figure that the waste wind turbine blade-based porous carbon prepared in the present invention is a spherical structure with developed pores, which is formed by the corrosion effect of HF and the pore-forming effect of KOH.

[0121] (2) The structural properties of the discarded wind turbine blade-based porous carbon prepared in Examples 1 to 4 are shown in Table 1.

[0122] Table 1 Structural properties of the discarded wind turbine blade-based porous carbon prepared in Examples 1 to 4

[0123]

[0124] As shown in Table 1, the specific surface area of ​​the porous carbons derived from discarded wind turbine blades ranks as follows: Example 2 > Example 4 > Example 1 > Example 3, directly confirming the significant regulatory effect of preparation conditions on pore structure. Further analysis of structural parameters reveals that the specific surface area and microporosity of the porous carbon derived from discarded wind turbine blades prepared in Example 2 are significantly superior to those of the other samples. Its highly developed microporous structure and concentrated pore size distribution, combined with its high micropore volume, demonstrate that optimized conditions precisely balance pore structure parameters, enabling adaptation to diverse application scenarios.

[0125] (3) The adsorption performance of the discarded wind turbine blade-based porous carbon prepared in Examples 1 to 4 on different substances was tested. The specific tests are as follows:

[0126] 1) Testing the adsorption performance of CO2 by porous carbon based on discarded wind turbine blades

[0127] A CO2 adsorption experiment was carried out on the discarded wind turbine blade-based porous carbon samples using a BSD-VVS static adsorption instrument (Beijing Best Instrument Technology Co., Ltd.). Before the adsorption experiment, the discarded wind turbine blade-based porous carbon samples were degassed in the fully automatic in-situ degassing mode of the test position. After degassing, adsorption measurements were carried out under conditions of a temperature of 293K and a pressure range of 0 to 500kPa. The adsorption isotherms of CO2 on the discarded wind turbine blade-based porous carbon samples prepared in Examples 1 to 4 were measured, and the commonly used adsorption isotherm model Langmuir-Freundlich model (also known as the Sips model) was used to fit the adsorption isotherm data.

[0128] The mathematical expression of the Sips model is shown in Equation (a). This empirical model combines the Langmuir and Freundlich isotherms and is used to predict heterogeneous adsorption systems. At low adsorbate concentrations, it can be reduced to a Freundlich isotherm; at high concentrations, it can predict the monolayer adsorption capacity characteristics of the Langmuir isotherm.

[0129]

[0130] Where: q represents the equilibrium adsorption capacity, mmol / g; p represents the equilibrium pressure, kPa; q s is the saturated adsorption capacity, mmol / g; b is the Sips adsorption equilibrium constant, 1 / kPa; n is the heterogeneity parameter.

[0131] The equilibrium adsorption capacity of CO2 of the waste wind turbine blade-based porous carbon prepared in Examples 1 to 4 was measured. The results are as follows: Figure 2 shown.

[0132] from Figure 2 The results show that the adsorption capacity of the porous carbons based on discarded wind turbine blades prepared under different conditions varies. The equilibrium adsorption capacity of CO2 by the porous carbons based on discarded wind turbine blades prepared in Example 2 is the highest, while that by Example 3 is the lowest. Furthermore, the equilibrium adsorption capacity data for CO2 by Examples 1 to 4 span a wide range, indicating that the porous carbons based on discarded wind turbine blades prepared in the present invention have a strong affinity for CO2 and possess exceptional adsorption capacity due to their porous structure. Furthermore, the equilibrium adsorption capacity is consistent with the fitted curve, indicating that the adsorption of Examples 1 to 4 conforms to the Sips model.

[0133] 2) Adsorption performance test of olefins and sulfides on porous carbon based on discarded wind turbine blades

[0134] The dynamic adsorption performance of porous carbon based on discarded wind turbine blades for olefins (a four-component mixture of C2H6 / C2H4 / C3H8 / C3H6) and sulfides (H2S, COS, CH3SH, CS2, CH3SCH3, CH4) was determined on a fixed-bed adsorption column. The adsorption column was loaded with a porous carbon sample based on discarded wind turbine blades. The test environment temperature was maintained at 298K. The feed gas entered the fixed-bed adsorption column at a flow rate of 84mL / min. The tail gas was collected at the outlet of the adsorption column at regular intervals and the gas sample was analyzed by gas chromatograph. The change in olefin or sulfide content over time was analyzed based on the change in sample composition at each moment until the outlet content was the same as the inlet content. At this time, the bed was considered to have reached dynamic adsorption saturation.

[0135] The dynamic adsorption performance of sulfide on the porous carbon based on discarded wind turbine blades prepared in Example 1 and Example 2 was measured. The results are as follows: Figure 3 As shown. Figure 3 It can be seen that the adsorption capacity of the discarded wind turbine blade-based porous carbon prepared in Example 2 for five sulfur-containing gases (H2S, COS, CH3SH, CS2, CH3SCH3) is significantly increased compared with that in Example 1, and the order of size is: H2S>CH3SH>CH3SCH3>COS, among which the adsorption amount of H2S is the highest, which is significantly better than that of other gases. This shows that the discarded wind turbine blade-based porous carbon has the strongest adsorption affinity for H2S.

[0136] The dynamic adsorption performance of alkanes / olefins on the porous carbons based on discarded wind turbine blades prepared in Example 1 and Example 2 was measured. The results are as follows: Figure 4 As shown. Figure 4 As can be seen from the results, the adsorption capacity of the discarded wind turbine blade-based porous carbon prepared in Example 2 was significantly higher than that of Example 1. Furthermore, at the same pressure, the adsorption capacity of olefins (C2H4 and C3H6) was significantly higher than that of the corresponding alkanes (C2H6 and C3H8), indicating that the discarded wind turbine blade-based porous carbon adsorbent has a higher affinity for olefins, likely due to the stronger binding of olefin double bonds to the surface active sites of the discarded wind turbine blade-based porous carbon. The adsorption capacity of C3H6 was slightly lower than that of C2H4, possibly due to its larger molecular size, but it was still superior to C3H8 overall.

[0137] 3) Test of static saturated adsorption capacity of gaseous VOCs by porous carbon based on discarded wind turbine blades

[0138] The static saturated adsorption capacity of gaseous VOCs by the discarded wind turbine blade-based porous carbon was measured by weighing. 1 g of the discarded wind turbine blade-based porous carbon sample prepared in Example 2 was quickly weighed into a weighing bottle. The weighing bottle and a 50 mL beaker containing 10 mL of adsorbate were placed in a sealed container and subjected to static adsorption at 35°C for 24 hours to ensure full contact and saturation of the VOCs. During the experiment, the mass of the weighing bottle, the total mass of the weighing bottle and adsorbent before adsorption, and the total mass of the weighing bottle and adsorbent after adsorption were weighed separately, and these masses were recorded as m1, m2, and m3, respectively.

[0139] After the static adsorption experiment is completed, the static saturated adsorption capacity at the adsorption temperature is calculated according to the experimental data using formula (b):

[0140]

[0141] Among them, q s is the static saturated adsorption capacity of the adsorbent, mg / g adsorbent; m1 is the mass of the weighing bottle, g; m2 is the total mass of the weighing bottle and adsorbent before adsorption, g; m3 is the total mass of the weighing bottle and adsorbent after adsorption saturation, g.

[0142] The static saturated adsorption capacity of VOCs on the waste wind turbine blade-based porous carbon prepared in Example 2 was measured. The results are as follows: Figure 5 As shown. Figure 5 It can be seen that the waste wind turbine blade-based porous carbon prepared in Example 2 showed excellent static adsorption performance for five VOCs. The static saturated adsorption capacities of n-hexane of alkanes, ethyl acetate of esters, toluene of aromatic hydrocarbons, methanol of alcohols and acetone of ketones on the waste wind turbine blade-based porous carbon were 140.53, 226.92, 112.72, 120.75 and 220.53 mg / g, respectively. In particular, the adsorption amounts of ethyl acetate and acetone reached more than 220 mg / g, indicating that the waste wind turbine blade-based porous carbon prepared by the present invention has great potential in VOCs treatment.

[0143] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A method for preparing porous carbon based on discarded wind turbine blades, characterized in that: The following steps are involved: Carbonizing powder of discarded wind turbine blades in a first protective gas, and etching the obtained carbonized material to obtain a primary porous carbon material; The primary porous carbon material and an activator are mixed, and pyrolysis activation is performed in a second protective gas to obtain waste wind turbine blade-based porous carbon.

2. The preparation method according to claim 1, characterized in that The etching solution used in the etching is HF solution; the concentration of the HF solution is 3-20 wt%.

3. The preparation method according to claim 1, characterized in that The activator includes KOH solution, KOH powder, NaOH powder, NaOH solution, ZnCl2 solution, H3PO4 solution, water vapor or CO2 gas.

4. The preparation method according to claim 3, characterized in that When the activator is a KOH solution or a NaOH solution, the mass ratio of KOH to the primary porous carbon material in the KOH solution or the mass ratio of NaOH to the primary porous carbon material in the NaOH solution is independently 1 to 4:1; the primary porous carbon material and the activator are mixed so as to immerse the primary porous carbon material in a KOH solution or a NaOH solution; the immersion time is 6 to 12 hours; the temperature of the pyrolysis activation is 600 to 900°C, and the holding time is 0.5 to 3 hours.

5. The preparation method according to claim 3, characterized in that When the activator is an H3PO4 solution, the mass ratio of the volume of the H3PO4 solution to the primary porous carbon material is (2~5)mL:1g; the concentration of the H3PO4 solution is 40~85wt%; the primary porous carbon material and the activator are mixed so that the primary porous carbon material is immersed in the H3PO4 solution; the immersion time is 6~24h; the temperature of the pyrolysis activation is 400~700℃, and the insulation time is 0.5~3h.

6. The preparation method according to claim 3, characterized in that When the activator is a ZnCl2 solution, the mass ratio of ZnCl2 to the primary porous carbon material in the ZnCl2 solution is 1 to 3:1; the primary porous carbon material and the activator are mixed so as to immerse the primary porous carbon material in the ZnCl2 solution; the immersion time is 6 to 24 hours; the temperature of the pyrolysis activation is 400 to 800°C, and the insulation time is 1 to 4 hours.

7. The preparation method according to claim 3, characterized in that When the activating agent is CO2 gas, the flow rate of the CO2 gas is 50 to 300 mL / min; the temperature of the pyrolysis activation is 800 to 1000°C, and the holding time is 0.5 to 4 hours.

8. The preparation method according to claim 3, characterized in that When the activator is water vapor, the temperature of the pyrolysis activation is 800-1000° C., and the holding time is 0.5-3.0 h; the activator is introduced in the form of a mixture of water vapor and a carrier gas; the flow rate of the water vapor is 0.4-2.0 L / min; the total flow rate of the mixture of water vapor and carrier gas is 3-10 L / min; and the partial pressure of water vapor in the mixture of water vapor and carrier gas is 10-30 vol%.

9. The waste wind turbine blade-based porous carbon prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The discarded wind turbine blade-based porous carbon includes a silicon-oxygen skeleton and a porous carbon structure constructed on the silicon-oxygen skeleton through Si-OC interface bonding; it has a multi-level microporous structure, and the multi-level microporous structure includes a microporous structure, an ordered mesoporous structure and a macroporous structure; the pore diameter of the microporous structure is 1 to 3 nm; the pore diameter of the ordered mesoporous structure is 5 to 10 nm; and the pore diameter of the macroporous structure is 20 to 30 nm.

10. Use of the discarded wind turbine blade-based porous carbon according to claim 9 in energy storage and conversion, environmental management, catalysis, or adsorption and separation.

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