A porous composite material for sulfur dioxide capture and a method for preparing the same
By constructing a synergistic system of aluminum-doped porous carbon fiber skeleton and metal composite active components, the problems of easy pulverization and insufficient strength of porous composite materials in desulfurization towers were solved, achieving efficient sulfur dioxide capture and improved mechanical stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING JIAOTONG UNIV
- Filing Date
- 2026-01-09
- Publication Date
- 2026-06-26
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Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention belongs to the field of porous adsorption materials technology, specifically a porous composite material for sulfur dioxide capture and its preparation method. Background Technology
[0002] Sulfur dioxide emitted from coal-fired boilers, smelting, and chemical industries needs to be efficiently removed in desulfurization towers through adsorption or solidification. Porous composite materials are widely used in wet or dry desulfurization towers due to their large specific surface area, abundant active sites, and good temperature resistance. Fly ash and red mud, as industrial solid wastes containing large amounts of silica, alumina, and other components, are abundant and inexpensive, making them important resources for preparing porous materials for adsorbing sulfur dioxide. However, these solid waste raw materials generally have disadvantages such as low reactivity, strong particle surface inertness, and difficulty in forming a uniform interconnected pore structure, which leads to the materials being prone to pulverization and insufficient strength under the high flow rate and circulation conditions of the desulfurization tower.
[0003] To improve the porosity and structural stability of porous materials, existing technologies have proposed various modification approaches, including using binders to form a stable framework, employing energy enhancement methods to increase the activation level of components in solid waste, and promoting pore structure generation through physical-chemical composite modification. These methods improve the specific surface area and mechanical properties of porous materials by enhancing interparticle bonding and promoting internal structural reorganization.
[0004] In the existing technical solutions, Chinese Patent No. CN108264279B discloses a method for preparing porous granular composite materials using red mud and fly ash as raw materials. The method involves mixing fly ash and red mud with cement as a binder to form uniform particles, and then activating the particles in a water vapor atmosphere using energy fields such as microwaves. This activates the internal metal oxides and promotes the structural reorganization of unburned carbon, thereby forming a porous granular composite material with a certain strength and pore structure.
[0005] In the above technical solution, cement is added to form a gel phase to bind fly ash and red mud particles. Under microwave action, cement is prone to dehydration and uneven setting, resulting in discontinuous skeleton, loose interfacial bonding, and decreased mechanical properties. Furthermore, under the local thermal effect generated by microwaves, the silica-alumina gel and metal oxide phase formed by fly ash and red mud are often unevenly distributed, resulting in poor pore wall density and weak interfacial bonding, making the material insufficient in compressive strength. At the same time, unburned carbon undergoes rapid rearrangement during microwave activation, which, although it can form pores, can also easily cause the pore structure to be excessively loose, making the overall structure more fragile. The porous composite material prepared in this way is difficult to meet the stability requirements of high flow rate impact and long-term cyclic operation in industrial desulfurization towers. Summary of the Invention
[0006] The purpose of this invention is to provide a porous composite material for sulfur dioxide capture and its preparation method. By constructing a synergistic system of aluminum-doped porous carbon fiber skeleton and metal composite active components, and compounding it with materials such as silane-modified fly ash and red mud, the material's ability to capture sulfur dioxide is significantly improved. At the same time, it maintains excellent mechanical stability under high adsorption load conditions, so as to meet the application requirements of high strength of adsorption materials under complex gas-liquid scouring conditions in desulfurization towers.
[0007] The objective of this invention can be achieved through the following technical solutions:
[0008] A porous composite material for capturing sulfur dioxide, comprising, by weight, the following raw materials:
[0009] 40-60 parts of silane-modified fly ash, 2-4 parts of metal composite modified porous carbon fiber, 40-60 parts of red mud, 10-15 parts of diatomaceous earth, 5-10 parts of calcium hydroxide, 10-20 parts of water glass, 1-3 parts of aluminum powder, and 2-6 parts of deionized water.
[0010] This invention also provides a method for preparing a porous composite material for sulfur dioxide capture, comprising the following steps:
[0011] Alkali-activated red mud composite slurry was placed in a reactor, and an aluminum powder suspension prepared by mixing aluminum powder and deionized water at a mass ratio of 1:2 was added. After stirring at 25-35℃ for 3-5 minutes, the mixed slurry was poured into a spherical mold with a diameter of 10 mm for preliminary curing. Then the mold was transferred to a tube furnace and calcined at 450-550℃ for 30-40 minutes. After cooling to room temperature, a porous composite material for sulfur dioxide capture was obtained.
[0012] Furthermore, the mass ratio of alkali-activated red mud composite slurry, aluminum powder, and deionized water is 100-150:1-3:2-6.
[0013] Furthermore, the preparation process of alkali-activated red mud composite slurry is as follows:
[0014] Water glass and a 10 mol / L sodium hydroxide solution were placed in a reactor and stirred at 25-35℃ for 5-10 min. Then, silane-modified fly ash, metal-modified porous carbon fiber, red mud, diatomaceous earth and calcium hydroxide were added. The temperature was maintained and stirred for 5-10 min to obtain alkali-activated red mud composite slurry.
[0015] Furthermore, the ratio of the amounts of silane-modified fly ash, metal-modified porous carbon fiber, red mud, diatomaceous earth, calcium hydroxide, water glass, and sodium hydroxide solution is 40-60g: 2-4g: 40-60g: 10-15g: 5-10g: 10-20g: 40-60mL.
[0016] Furthermore, the preparation process of silane-modified fly ash is as follows:
[0017] γ-aminopropyltriethoxysilane, ethanol and deionized water were placed in a reaction vessel and stirred at 25-35℃ for 10-20 min. Fly ash was added and reacted at 25-35℃ for 2-4 h. The mixture was then filtered, washed, and vacuum dried to constant weight to obtain silane-modified fly ash.
[0018] Furthermore, the ratio of fly ash, γ-aminopropyltriethoxysilane, ethanol, and deionized water is 60-80g: 6-8g: 100-150mL: 8-10mL.
[0019] Furthermore, the preparation process of metal composite modified porous carbon fibers is as follows:
[0020] Aluminum-doped porous carbon fibers, ferric chloride hexahydrate, calcium chloride hexahydrate, deionized water, and ethanol were placed in a reaction vessel and stirred at 25-35℃ for 30-60 min. A 0.5 mol / L sodium hydroxide aqueous solution was added dropwise to adjust the pH to 10-12. The reaction was carried out at 25-35℃ for 10-20 min. The mixture was then filtered, washed, vacuum dried to constant weight, and mechanically sheared to obtain metal composite modified porous carbon fibers.
[0021] Furthermore, the ratio of aluminum-doped porous carbon fiber, ferric chloride hexahydrate, calcium chloride hexahydrate, sodium hydroxide solution, deionized water, and ethanol is 10-20g: 8-15g: 8-15g: 30-40mL: 60-80mL: 60-80mL.
[0022] Furthermore, the preparation process of aluminum-doped porous carbon fibers is as follows:
[0023] The aluminum-doped porous carbon fiber precursor was sandwiched between carbon plates and placed in a muffle furnace. The temperature was increased from 30°C to 240-280°C at a rate of 5°C / min, and the reaction was maintained at the same temperature for 1.5-2.5 hours. Then, it was placed in a tube furnace under nitrogen atmosphere protection and the temperature was increased from 30°C to 800-1000°C at a rate of 5°C / min, and the reaction was maintained at the same temperature for 1.5-2.5 hours to obtain aluminum-doped porous carbon fiber.
[0024] Furthermore, the preparation process of the aluminum-doped porous carbon fiber precursor is as follows:
[0025] Polyacrylonitrile, aluminum chloride hexahydrate, and N,N-dimethylformamide were placed in a reaction vessel and stirred at 25-35°C for 8-10 hours. The resulting solution was then transferred to an electrospinning apparatus for electrospinning. The spun fibers were deposited on a collecting plate and vacuum dried to constant weight to obtain aluminum-doped porous carbon fiber precursors.
[0026] Furthermore, the ratio of polyacrylonitrile, aluminum chloride hexahydrate, and N,N-dimethylformamide is 40-60g: 20-30g: 350-550mL.
[0027] The beneficial effects of this invention are:
[0028] 0. The porous composite material for sulfur dioxide capture prepared in this invention introduces aluminum-based components during the carbon fiber preparation process and incorporates metal components such as iron and calcium in subsequent steps. This allows the carbon fiber to simultaneously possess the synergistic characteristics of metal reinforcement strength and porous structure-enabling active sites. During the aluminum-doped pre-oxidation and carbonization stages, aluminum ions are gradually converted into Al-O groups, which not only induces the directional rearrangement of the polyacrylonitrile carbon skeleton and the formation of a stable microporous structure, but also significantly improves the rigidity and thermal stability of the fiber body, thereby providing a reliable mechanical support foundation for the porous carbon skeleton. The resulting porous structure further enhances the biocompatibility of metals such as iron and calcium. The loading and anchoring of the components provide a large number of microporous spaces and active sites, effectively preventing the metal components from agglomerating or being lost during preparation and use, and promoting their high dispersion and stability. The resulting microporous structure and highly dispersed metal components together enhance the material's adsorption and fixation capacity for sulfur dioxide. The metal relative plays a reinforcing and supporting role on the carbon skeleton, while the porous structure provides the metal with an efficient carrying platform and reaction interface. The two promote each other in structure and function, jointly constructing a stable fiber-reinforced network and forming a strong interfacial bond with the alkali-activated system, significantly improving the material's compressive strength and long-term operational stability.
[0029] 1. The porous composite material for sulfur dioxide capture prepared in this invention modifies the surface of fly ash with γ-aminopropyltriethoxysilane. The Si-OH formed by the hydrolysis of silane condenses with the hydroxyl groups on the fly ash surface to form Si-O-Si covalent bonds, which significantly improves the reactivity of the particle surface. Moreover, the amino groups at the silane end can undergo hydrogen bonding, coordination and ionic bonding with Si-OH, Al-OH and other groups in the gel system formed by alkali activation, thereby significantly improving the interfacial bonding force between the components of the system. This interfacial strengthening not only improves the mechanical load-bearing capacity, but also provides a more stable reaction interface for the subsequent adsorption of sulfur dioxide. At the same time, the surface silane layer can promote the uniform growth of silica-alumina gel on the particle surface, reduce gel shedding during molding and calcination, make the pore walls more complete and dense, and greatly improve the compressive strength and structural stability of the material.
[0030] 2. The porous composite material for sulfur dioxide capture prepared in this invention, after introducing metal-modified carbon fibers, allows its surface-active groups to form hydrogen bonds, coordination bonds, or ionic bonds with functional groups such as Si-OH and -NH2 on the surface of silane-modified fly ash. This establishes a stable multi-point interfacial network between the carbon fibers and the fly ash skeleton. The mutual promotion of the interface between the two not only improves the nucleation, adhesion, and continuous growth of the gel on the fly ash surface, but also enhances the dispersion and loading capacity of the carbon fibers in the system. This achieves synergistic reinforcement between the particulate phase and the fiber phase, significantly improving the overall mechanical properties and structural stability of the material. On the other hand, the microchannel structure constructed by the carbon fibers and the dense gel layer formed by the modified fly ash work together to provide a more stable bubble support and nucleation environment during the foaming stage, improving pore uniformity and reducing bubble wall collapse. At the same time, the surface-functionalized fly ash and carbon fiber interface has more active sites and a larger specific surface area, significantly enhancing the adsorption capacity of the material for sulfur dioxide and further improving its application performance. Detailed Implementation
[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0032] Example 1: This example provides a metal-modified porous carbon fiber in a porous composite material for sulfur dioxide capture, which is prepared through the following steps:
[0033] S1: 40g polyacrylonitrile, 20g aluminum chloride hexahydrate and 350mL N,N-dimethylformamide were placed in a reaction vessel and stirred at 200r / min for 8h at 25℃. The resulting solution was dispensed in batches of 30mL and transferred sequentially to an electrospinning device. The solution injection rate was adjusted to 6mL / h, a voltage of 25kV was applied, and the receiving distance was set to 20cm for electrospinning. The spun fibers were deposited on a collecting plate and vacuum dried at 60℃ to constant weight to obtain aluminum-doped porous carbon fiber precursor.
[0034] S2: 30g of aluminum-doped porous carbon fiber precursor was clamped with a carbon plate and placed in a muffle furnace. The temperature was increased from 30℃ to 240℃ at a rate of 5℃ / min and maintained at the same temperature for 1.5h. Then, it was placed in a tube furnace under nitrogen atmosphere protection and the temperature was increased from 30℃ to 800℃ at a rate of 5℃ / min and maintained at the same temperature for 1.5h to obtain aluminum-doped porous carbon fiber.
[0035] S3: Place 10g of aluminum-doped porous carbon fiber, 8g of ferric chloride hexahydrate, 8g of calcium chloride hexahydrate, 60mL of deionized water and 60mL of ethanol in a reaction vessel, stir at 200r / min for 30min at 25℃, add 30mL of 0.5mol / L sodium hydroxide aqueous solution, adjust the pH to 10, react at 25℃ for 10min, filter, wash the filter cake twice with deionized water, vacuum dry at 60℃ to constant weight, and perform mechanical shearing to control the average fiber length to 1mm to obtain metal composite modified porous carbon fiber.
[0036] Example 2: This example provides a metal-modified porous carbon fiber in a porous composite material for sulfur dioxide capture, prepared through the following steps:
[0037] S1: 50g polyacrylonitrile, 25g aluminum chloride hexahydrate and 450mL N,N-dimethylformamide were placed in a reaction vessel and stirred at 250r / min for 9h at 30℃. The resulting solution was dispensed in batches of 40mL and transferred sequentially to an electrospinning device. The solution injection rate was adjusted to 7mL / h, a voltage of 26kV was applied, and the receiving distance was set to 21cm for electrospinning. The spun fibers were deposited on a collecting plate and vacuum dried at 70℃ to constant weight to obtain aluminum-doped porous carbon fiber precursor.
[0038] S2: 40g of aluminum-doped porous carbon fiber precursor was clamped with a carbon plate and placed in a muffle furnace. The temperature was increased from 30℃ to 260℃ at a rate of 5℃ / min and maintained at the same temperature for 2 hours. Then, it was placed in a tube furnace under nitrogen atmosphere protection and the temperature was increased from 30℃ to 900℃ at a rate of 5℃ / min and maintained at the same temperature for 2 hours to obtain aluminum-doped porous carbon fiber.
[0039] S3: 15g of aluminum-doped porous carbon fiber, 13g of ferric chloride hexahydrate, 13g of calcium chloride hexahydrate, 70mL of deionized water and 70mL of ethanol were placed in a reaction vessel and stirred at 250r / min for 45min at 30℃. 35mL of 0.5mol / L sodium hydroxide aqueous solution was added to adjust the pH to 11. The reaction was carried out at 30℃ for 15min. The mixture was filtered, and the filter cake was washed three times with deionized water. It was then vacuum dried at 70℃ to constant weight and mechanically sheared to control the fiber length to 2mm to obtain metal composite modified porous carbon fiber.
[0040] Example 3: This example provides a metal-modified porous carbon fiber in a porous composite material for sulfur dioxide capture, prepared through the following steps:
[0041] S1: 60g polyacrylonitrile, 30g aluminum chloride hexahydrate and 550mL N,N-dimethylformamide were placed in a reaction vessel and stirred at 300r / min for 10h at 35℃. The resulting solution was dispensed in batches of 50mL and transferred sequentially to an electrospinning device. The solution injection rate was adjusted to 8mL / h, a voltage of 27kV was applied, and the receiving distance was set to 22cm for electrospinning. The spun fibers were deposited on a collecting plate and vacuum dried at 80℃ to constant weight to obtain aluminum-doped porous carbon fiber precursor.
[0042] S2: 50g of aluminum-doped porous carbon fiber precursor was clamped with a carbon plate and placed in a muffle furnace. The temperature was increased from 30℃ to 280℃ at a rate of 5℃ / min and maintained at the same temperature for 2.5h. Then, it was placed in a tube furnace under nitrogen atmosphere protection and the temperature was increased from 30℃ to 1000℃ at a rate of 5℃ / min and maintained at the same temperature for 2.5h to obtain aluminum-doped porous carbon fiber.
[0043] S3: 20g of aluminum-doped porous carbon fiber, 15g of ferric chloride hexahydrate, 15g of calcium chloride hexahydrate, 80mL of deionized water and 80mL of ethanol were placed in a reaction vessel and stirred at 300r / min for 60min at 35℃. 40mL of 0.5mol / L sodium hydroxide aqueous solution was added to adjust the pH to 12. The reaction was carried out at 35℃ for 20min. The mixture was filtered, and the filter cake was washed four times with deionized water. It was then vacuum dried at 80℃ to constant weight and mechanically sheared to control the fiber length to 3mm to obtain metal composite modified porous carbon fiber.
[0044] The metal-modified porous carbon fibers prepared in Examples 1-3 above, through the introduction of aluminum chloride hexahydrate into the electrospinning system, cause the aluminum salt to decompose, migrate, and release gas during the pre-oxidation and high-temperature carbonization stages, promoting the formation of a hierarchical pore structure inside the polyacrylonitrile fiber. During the carbonization process, aluminum is anchored to the carbon skeleton in an Al-OC / Al-NC coordination manner, achieving atomic-level doping, thereby obtaining aluminum-doped porous carbon fibers with high specific surface area and abundant active sites. Based on this, the aluminum-doped porous carbon fibers are dispersed in a water and ethanol mixture, introducing Fe... 3+ With Ca 2+ Under alkaline conditions, the metal ions undergo in-situ hydrolysis and precipitation reactions, and the resulting iron hydroxide and calcium hydroxide are uniformly loaded and firmly anchored on the surface and inside the pores of the porous carbon fiber, thus obtaining metal composite modified porous carbon fiber.
[0045] Example 4: This example provides a porous composite material for sulfur dioxide capture, which is prepared through the following steps:
[0046] Step 1: Place 6g of γ-aminopropyltriethoxysilane, 80mL of ethanol and 8mL of deionized water in a reaction vessel, stir at 200r / min for 10min at 25℃, add 60g of fly ash, and react at 25℃ for 2h. After the reaction is complete, filter, wash the filter cake twice with deionized water and ethanol, and vacuum dry at 50℃ to constant weight to obtain silane-modified fly ash.
[0047] Step 2: Place 10g of water glass and 40mL of 10mol / L sodium hydroxide solution in a reaction vessel. Stir at 200r / min for 5min at 25℃. Then add 40g of silane-modified fly ash, 2g of metal composite modified porous carbon fiber prepared in Example 1, 40g of red mud, 10g of diatomaceous earth and 5g of calcium hydroxide. Maintain the same temperature and stir at 200r / min for 5min to obtain alkali-activated red mud composite slurry.
[0048] Step 3: Place 100g of alkali-activated red mud composite slurry in a reactor, add 1g of aluminum powder and 2g of deionized water in a mass ratio of 1:2 to prepare an aluminum powder suspension, stir at 200r / min for 3min at 25℃, pour the mixed slurry into a spherical mold with a diameter of 10mm, let it stand for 8h for preliminary curing, then transfer the mold to a tube furnace and calcine at 450℃ for 30min, cool to room temperature, and take out the spherical particles to obtain a porous composite material for sulfur dioxide capture.
[0049] Example 5: This example provides a porous composite material for sulfur dioxide capture, which is prepared through the following steps:
[0050] Step 1: Place 7g of γ-aminopropyltriethoxysilane, 90mL of ethanol and 9mL of deionized water in a reaction vessel, stir at 250r / min for 15min at 30℃, add 70g of fly ash, and react at 30℃ for 3h. After the reaction is complete, filter, wash the filter cake three times with deionized water and ethanol, and vacuum dry at 55℃ to constant weight to obtain silane-modified fly ash.
[0051] Step 2: Place 15g of water glass and 50mL of 10mol / L sodium hydroxide solution in a reaction vessel, stir at 250r / min for 8min at 30℃, then add 50g of silane-modified fly ash, 3g of metal composite modified porous carbon fiber prepared in Example 2, 50g of red mud, 12g of diatomaceous earth and 8g of calcium hydroxide, and maintain the temperature while stirring at 250r / min for 8min to obtain alkali-activated red mud composite slurry.
[0052] Step 3: Place 120g of alkali-activated red mud composite slurry in a reactor, add 2g of aluminum powder and 4g of deionized water in a mass ratio of 1:2 to prepare an aluminum powder suspension, stir at 250r / min for 4min at 30℃, pour the mixed slurry into a 10mm diameter spherical mold, let it stand for 9h for preliminary curing, then transfer the mold to a tube furnace and calcine at 500℃ for 35min, cool to room temperature, and remove the spherical particles to obtain a porous composite material for sulfur dioxide capture.
[0053] Example 6: This example provides a porous composite material for sulfur dioxide capture, which is prepared through the following steps:
[0054] Step 1: Place 8g of γ-aminopropyltriethoxysilane, 100mL of ethanol and 10mL of deionized water in a reaction vessel, stir at 300r / min for 20min at 35℃, add 80g of fly ash, and react at 35℃ for 4h. After the reaction is complete, filter, wash the filter cake 4 times with deionized water and ethanol, and vacuum dry at 60℃ to constant weight to obtain silane-modified fly ash.
[0055] Step 2: Place 20g of water glass and 60mL of 10mol / L sodium hydroxide solution in a reaction vessel, stir at 300r / min for 10min at 35℃, then add 60g of silane-modified fly ash, 4g of metal composite modified porous carbon fiber prepared in Example 3, 60g of red mud, 15g of diatomaceous earth and 10g of calcium hydroxide, and maintain the temperature while stirring at 300r / min for 10min to obtain alkali-activated red mud composite slurry.
[0056] Step 3: Place 150g of alkali-activated red mud composite slurry in a reactor, add 3g of aluminum powder and 6g of deionized water in a mass ratio of 1:2 to prepare an aluminum powder suspension, stir at 300r / min for 5min at 35℃, pour the mixed slurry into a 10mm diameter spherical mold, let it stand for 10h for preliminary curing, then transfer the mold to a tube furnace and calcine at 550℃ for 40min, cool to room temperature, and remove the spherical particles to obtain a porous composite material for sulfur dioxide capture.
[0057] The porous composite material for sulfur dioxide capture prepared above involves organosilylation modification of the fly ash surface with γ-aminopropyltriethoxysilane. A Si-O-Si network is formed on the fly ash particle surface through the hydrolysis-condensation reaction of silane, while simultaneously introducing amino functional groups. Subsequently, in a highly alkaline environment constructed with water glass and sodium hydroxide solution, silanized fly ash, metal-modified porous carbon fibers, red mud, diatomaceous earth, and calcium hydroxide are dispersed together to form an alkali-activated composite slurry. The active Si-O-Al structures in the fly ash and red mud undergo a dissolution-repolymerization process under strongly alkaline conditions, generating NASH / CASH gel. Further, an aluminum powder suspension is introduced into the composite slurry, utilizing the in-situ reaction of aluminum powder in the highly alkaline system to generate a large number of microbubbles, forming a uniform interconnected pore structure inside the spherical particles. After static curing in a spherical mold, the inorganic gel and porous structure are further stabilized by calcination, resulting in the porous composite material for sulfur dioxide capture.
[0058] Comparative Example 1: Based on Example 5, commercially available carbon fiber was used instead of the metal composite modified porous carbon fiber prepared in Example 2 in step two, while the other steps remained unchanged.
[0059] Comparative Example 2: Based on Example 5, commercially available fly ash was used instead of the silane-modified fly ash in step two, while the other steps remained unchanged.
[0060] Comparative Example 3: Based on Example 5, the metal composite modified porous carbon fiber prepared in Example 2 in step 2 was removed, while the other steps remained unchanged.
[0061] In the above embodiments and comparative examples, the purchased fly ash was produced by Changshu Suyu Tianrun Fly Ash Co., Ltd., and was screened through a 200-mesh sieve before use; the red mud was produced by China Aluminum Shandong Co., Ltd., and was Bayer process red mud, which was dried, ground, and then screened through a 100-mesh sieve; the carbon fiber was produced by Jiangsu Shunju Carbon Fiber Products Co., Ltd., and was short-cut carbon fiber with an average length of 2mm; the aluminum powder was produced by Henan Xinsheng Aluminum Powder Co., Ltd., and had an average particle size of 10μm; the diatomaceous earth was produced by Qingdao Chuanyi Diatomaceous Earth Co., Ltd., and was screened through a 200-mesh sieve before use; the water glass was produced by Yourui Refractory Materials Co., Ltd., and had a modulus of 3.3; and the polyacrylonitrile was produced by Aladdin Biochemical Technology Co., Ltd., and had an average molecular weight of 100,000.
[0062] The performance of a porous composite material for sulfur dioxide capture prepared in Examples 4-6 and Comparative Examples 1-3 was tested, and the test results are shown in Table 1.
[0063] Sample preparation: In accordance with standard GB / T 30202.3-2013, the porous composite materials obtained in the above examples and comparative examples were dried in a vacuum drying oven at 80℃ for 12h, which served as samples for subsequent performance tests.
[0064] Pore volume: Referring to standard GB / T 7702.20-2025, after the sample is dried and degassed, the true density and particle density of the sample are determined by a true density analyzer, and the pore volume is calculated accordingly. The larger the pore volume, the more developed the pore structure of the material and the higher the adsorption potential for sulfur dioxide gas.
[0065] Adsorption capacity: Referring to standard GB / T 37186-2018, the sample was loaded into a constant temperature fixed bed reactor, and after nitrogen pretreatment, simulated flue gas with a concentration of 1500 ppm of sulfur dioxide was introduced. The concentration of sulfur dioxide at the outlet was monitored in real time by ultraviolet fluorescence method to obtain the adsorption capacity of the material for sulfur dioxide. The larger the adsorption capacity, the better the adsorption performance of the material.
[0066] Wear resistance: Referring to standard GB / T 30202.3-2013, the sample was pre-sieved on a vibrating screen using the smallest aperture as the sieve layer. The pre-sieved sample was then added to the drum of the strength tester, sealed, and run for 20 minutes. After the test, the sample was removed and sieved again on the vibrating screen using the same sieve layer as the pre-sieved sample. The material on the sieve was collected and weighed. The wear resistance strength was calculated based on the mass fraction ω of the material on the sieve. The higher the wear resistance strength, the better the wear resistance of the material.
[0067] Compressive strength: Refer to standard GB / T 30202.3-2013, take 20 samples, place the sample in the V-groove of the fixture, turn on the compressive strength tester, and record the pressure value at the moment the sample is crushed. Repeat the steps for the remaining sample and take the average value to obtain the compressive strength. The higher the compressive strength, the better the compressive strength of the porous composite material.
[0068] Table 1 Performance Test Table of Porous Composite Materials for Sulfur Dioxide Capture
[0069]
[0070] As shown in Table 1, the performance of Examples 4-6 is superior to that of Comparative Examples 1-3. This demonstrates that the present invention constructs a multi-metal synergistic adsorption system composed of an aluminum-doped carbon fiber skeleton, iron active centers, and calcium alkaline sites, thereby forming a structurally stable and highly efficient metal composite modified carbon fiber. At the same time, mineral-based materials such as red mud, diatomaceous earth, and silane-modified fly ash are used in conjunction with the metal composite modified carbon fiber to construct a multi-scale porous structure, so that the composite material forms a porous network with both chemical adsorption sites and physical trapping capabilities. The foaming reaction of aluminum powder in the alkali-activated system further increases the specific surface area of the material, enabling the composite material to significantly improve the adsorption and fixation capacity of sulfur dioxide while ensuring excellent mechanical properties.
[0071] As shown in Table 1, the mechanical and adsorption properties of Comparative Example 3 decreased significantly, indicating that the metal composite modified carbon fiber prepared in this invention improves the thermal stability and compressive strength of the fiber by introducing aluminum-based components during electrospinning, which are then uniformly distributed in the carbon fiber skeleton with an Al-OC anchoring structure after carbonization. Subsequently, by depositing iron and calcium metal hydroxides in situ under alkaline conditions, a multi-metal composite layer with both iron-based active centers and calcium-based alkaline sites is formed on the carbon fiber surface, promoting the oxidation, coordination, and chemical adsorption of sulfur dioxide, and significantly improving the sulfur dioxide capture capacity of the material. At the same time, the multi-metal composite structure can effectively enhance the compactness and mechanical stability of the carbon fiber surface, achieving the effect of simultaneously improving the mechanical strengthening and adsorption properties of the material.
[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.
Claims
1. A porous composite material for capturing sulfur dioxide, characterized in that, By weight, it includes the following raw materials: 40-60 parts of silane-modified fly ash, 2-4 parts of metal composite modified porous carbon fiber, 40-60 parts of red mud, 10-15 parts of diatomaceous earth, 5-10 parts of calcium hydroxide, 10-20 parts of water glass, 1-3 parts of aluminum powder, and 2-6 parts of deionized water. The specific preparation process of the porous composite material for sulfur dioxide capture is as follows: Step 1: Place water glass and a 10 mol / L sodium hydroxide solution in a reaction vessel, stir at 25-35℃ for 5-10 min, then add silane-modified fly ash, metal composite modified porous carbon fiber, red mud, diatomaceous earth and calcium hydroxide, maintain the temperature and stir for 5-10 min to obtain alkali-activated red mud composite slurry. Step 2: Place the alkali-activated red mud composite slurry in a reactor, add an aluminum powder suspension prepared by mixing aluminum powder and deionized water at a mass ratio of 1:2, stir at 25-35℃ for 3-5 minutes, pour the mixed slurry into a spherical mold with a diameter of 10mm for preliminary solidification, and then transfer the mold to a tube furnace for calcination and cooling to room temperature to obtain a porous composite material for sulfur dioxide capture. The metal-modified porous carbon fiber is prepared by the following steps: Aluminum-doped porous carbon fibers, ferric chloride hexahydrate, calcium chloride hexahydrate, deionized water, and ethanol were placed in a reaction vessel and stirred at 25-35℃ for 30-60 min. A 0.5 mol / L sodium hydroxide aqueous solution was added dropwise to adjust the pH to 10-12. The reaction was carried out at 25-35℃ for 10-20 min. The mixture was then filtered, washed, vacuum dried to constant weight, and mechanically sheared to obtain metal composite modified porous carbon fibers.
2. The porous composite material for sulfur dioxide capture according to claim 1, characterized in that, The ratio of aluminum-doped porous carbon fiber, ferric chloride hexahydrate, calcium chloride hexahydrate, sodium hydroxide solution, deionized water and ethanol is 10-20g: 8-15g: 8-15g: 30-40mL: 60-80mL: 60-80mL.
3. The porous composite material for sulfur dioxide capture according to claim 2, characterized in that, The aluminum-doped porous carbon fiber is prepared by the following steps: The aluminum-doped porous carbon fiber precursor was sandwiched between carbon plates and placed in a muffle furnace. The temperature was increased from 30°C to 240-280°C at a rate of 5°C / min, and the reaction was maintained at the same temperature for 1.5-2.5 hours. Then, it was placed in a tube furnace under nitrogen atmosphere protection and the temperature was increased from 30°C to 800-1000°C at a rate of 5°C / min, and the reaction was maintained at the same temperature for 1.5-2.5 hours to obtain aluminum-doped porous carbon fiber.
4. The porous composite material for sulfur dioxide capture according to claim 3, characterized in that, The aluminum-doped porous carbon fiber precursor is prepared by the following steps: Polyacrylonitrile, aluminum chloride hexahydrate, and N,N-dimethylformamide were placed in a reaction vessel and stirred at 25-35°C for 8-10 hours. The resulting solution was then transferred to an electrospinning apparatus for electrospinning. The spun fibers were deposited on a collecting plate and vacuum dried to constant weight to obtain aluminum-doped porous carbon fiber precursors.
5. A porous composite material for sulfur dioxide capture according to claim 4, characterized in that, The ratio of polyacrylonitrile, aluminum chloride hexahydrate, and N,N-dimethylformamide is 40-60g: 20-30g: 350-550mL.
6. The porous composite material for sulfur dioxide capture according to claim 1, characterized in that, The silane-modified fly ash is prepared through the following steps: γ-aminopropyltriethoxysilane, ethanol and deionized water were placed in a reaction vessel and stirred at 25-35℃ for 10-20 min. Fly ash was added and reacted at 25-35℃ for 2-4 h. The mixture was then filtered, washed, and vacuum dried to constant weight to obtain silane-modified fly ash.
7. A porous composite material for sulfur dioxide capture according to claim 6, characterized in that, The ratio of fly ash, γ-aminopropyltriethoxysilane, ethanol and deionized water is 60-80g: 6-8g: 100-150mL: 8-10mL.
8. The method for preparing a porous composite material for sulfur dioxide capture according to claim 1, characterized in that, Includes the following steps: Step 1: Place water glass and a 10 mol / L sodium hydroxide solution in a reaction vessel, stir at 25-35℃ for 5-10 min, then add silane-modified fly ash, metal composite modified porous carbon fiber, red mud, diatomaceous earth and calcium hydroxide, maintain the temperature and stir for 5-10 min to obtain alkali-activated red mud composite slurry. Step 2: Place the alkali-activated red mud composite slurry in a reactor, add an aluminum powder suspension prepared by mixing aluminum powder and deionized water at a mass ratio of 1:2, stir at 25-35℃ for 3-5 minutes, pour the mixed slurry into a spherical mold with a diameter of 10mm for preliminary solidification, and then transfer the mold to a tube furnace for calcination and cooling to room temperature to obtain a porous composite material for sulfur dioxide capture.
9. The method for preparing a porous composite material for sulfur dioxide capture according to claim 8, characterized in that, The roasting temperature in step two is 450-550℃, and the time is 30-40 minutes.