Silicon carbide aerogel-based carbon dioxide adsorption material as well as preparation method and application thereof

Abstract

The invention discloses a silicon carbide aerogel-based carbon dioxide adsorption material and a preparation method and application thereof.The method comprises the steps that specific tetraalkoxy siloxane and carbonizable organic matter are adopted for preparing wet gel, then surface hydrophobic treatment and drying treatment are conducted to prepare dry gel, then heat treatment is conducted to generate silicon carbide aerogel, and the silicon carbide aerogel-based carbon dioxide adsorption material is obtained. Loading an amine compound with relatively high molecular weight on the silicon carbide aerogel to prepare the silicon carbide aerogel-based carbon dioxide adsorption material; practice shows that the silicon carbide aerogel-based carbon dioxide adsorption material prepared by the method disclosed by the invention has the advantages of high CO2 adsorption capacity, ultrafast adsorption kinetics, excellent thermal stability, low regeneration energy consumption and the like; due to the comprehensive advantages, the material is very suitable for carbon dioxide capture scenes with strict requirements on adsorption efficiency, operation cost and long-term stability.

Description

Technical Field

[0001] This invention relates to the field of gas adsorption technology, and more particularly to carbon dioxide gas adsorption materials, specifically to a silicon carbide aerogel-based carbon dioxide adsorption material, its preparation method, and its application. Background Technology

[0002] Excessive carbon dioxide emissions leading to global climate change have become a serious challenge, and developing efficient carbon capture technologies is one of the key pathways to achieving carbon neutrality. Among the many capture technologies, chemical absorption based on organic amine solutions has been industrialized, but it suffers from inherent drawbacks such as easy degradation of amine solutions, strong equipment corrosion, and high regeneration energy consumption, which limit its large-scale application prospects.

[0003] Solid amine adsorbents, as alternative carbon capture materials, exhibit advantages such as low energy consumption, environmental friendliness, and ease of operation by loading amine compounds onto the surface of porous solid supports, making them an important development direction. However, their performance is largely limited by the physicochemical properties of the support material. Currently used porous supports, such as mesoporous silica and metal-organic frameworks, generally suffer from a dual bottleneck of insufficient mass transfer and diffusion capacity and an imbalance in heat management: on the one hand, their pore structure easily leads to increased CO2 gas diffusion resistance and sluggish adsorption kinetics under high amine loading; on the other hand, the poor thermal conductivity of the materials themselves makes it difficult to quickly dissipate the heat of reaction generated during adsorption / desorption, which can easily cause local overheating, accelerate the thermal degradation of amine functional groups, and lead to irreversible degradation of adsorbent performance. Summary of the Invention

[0004] The purpose of this invention is to overcome one or more shortcomings in the prior art and provide a novel silicon carbide aerogel-based carbon dioxide adsorption material with outstanding carbon dioxide adsorption performance and its preparation method.

[0005] The present invention also provides an application of the above-mentioned carbon dioxide adsorption material in a carbon dioxide adsorption device.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A method for preparing a silicon carbide aerogel-based carbon dioxide adsorbent material, the method comprising: The compound shown in formula (I), the carbonizable organic material, and the solvent are mixed to form a wet gel; the mass ratio of the compound shown in formula (I) to the carbonizable organic material is 1:0.25-1.8. In the formula, R1, R2, R3, and R4 are independently selected from C. 1-6 alkyl; The wet gel is subjected to a surface hydrophobic treatment and then dried to prepare a dry gel; The dry gel is heat-treated to generate silicon carbide aerogel. An amine compound with a number average molecular weight of 600-100,000 was loaded onto the silicon carbide aerogel by a loading method.

[0007] In some embodiments of the present invention, R1, R2, R3, and R4 are independently selected from methyl, ethyl, propyl, or butyl.

[0008] According to one specific aspect of the present invention, the compound represented by formula (I) is tetraethyl orthosilicate. Practice has shown that tetraethyl orthosilicate can be used to prepare more desirable silicon carbide aerogels compared to other siloxane compounds.

[0009] In some embodiments of the present invention, the mass ratio of the compound represented by formula (Ⅰ) to the carbonizable organic matter is 1:0.35-1.5.

[0010] According to some specific aspects of the present invention, the mass ratio of the compound represented by formula (I) to the carbonizable organic matter is 1:0.35, 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6, 1:0.65, 1:0.7, 1:0.75, 1:0.8, 1:0.85, 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1.1, 1:1.15, 1:1.20, 1:1.25, 1:1.30, 1:1.35, 1:1.40, 1:1.45, 1:1.5, etc.

[0011] In some embodiments of the present invention, the carbonizable organic material may include, but is not limited to, phenolic resin, furfural resin, asphalt, or sugar compounds.

[0012] In some embodiments of the present invention, the solvent is composed of water and an alcohol solvent. In this invention, the use of a solvent composed of water and an alcohol solvent is more conducive to the formation of a wet gel, and also facilitates the formation of the desired dry gel after heat treatment.

[0013] Furthermore, the mass ratio of water to alcohol solvent is 1:2.5-13, and even more specifically, 1:4-8.

[0014] Furthermore, the alcohol solvent includes methanol, ethanol, or propanol.

[0015] In some embodiments of the present invention, the wet gel comprises, by weight percentage, 15%-35% of the compound shown in formula (I), 10%-25% of a carbonizable organic compound, 40%-65% of an alcohol solvent, and 5%-15% of water.

[0016] Furthermore, by mass percentage, the wet gel contains 18%-35% of the compound shown in formula (I), 12%-25% of carbonizable organic matter, 45%-60% of alcohol solvent, and 6%-12% of water.

[0017] In some embodiments of the present invention, during the preparation of the wet gel, an acid is added to adjust the pH of the system, and further, the pH of the system is adjusted to 2-4.

[0018] In some embodiments of the present invention, the acid may be hydrochloric acid, sulfuric acid, etc.

[0019] In some embodiments of the present invention, the preparation process of the wet gel includes: The compound shown in formula (Ⅰ), the carbonizable organic compound, and the solvent are mixed, and the pH of the system is adjusted to 2-4 with acid under stirring. A sol is formed under a first heating condition, and the mixture is allowed to stand to gel. Then, it is aged with an alcohol solvent under a second heating condition to obtain a wet gel.

[0020] Furthermore, the heating temperatures of the first heating condition and the second heating condition are controlled to be 40-60℃ respectively.

[0021] Furthermore, the alcohol solvent used in the aging process includes ethanol.

[0022] In some embodiments of the present invention, the aging is carried out using anhydrous ethanol, and further, the aging time is 12-36 hours.

[0023] In some embodiments of the present invention, the surface hydrophobic treatment process includes: The wet gel was immersed in a solution of the compound shown in formula (II) to obtain a hydrophobic gel. In the formula, R5, R6, and R7 are independently selected from C. 1-3 alkyl.

[0024] Furthermore, R5, R6, and R7 are independently selected from methyl, ethyl, and propyl.

[0025] According to one specific aspect of the present invention, the compound represented by formula (II) can be trimethylchlorosilane. By dissociating the alkyl silanol groups from the compound represented by formula (II), hydrogen bonds or condensations can be formed between the silanol groups in the wet gel. Furthermore, the increase in the number of alkyl groups enhances the hydrophobic function. In this invention, the imparting of hydrophobic effect is beneficial for preserving the pore structure during subsequent drying, avoiding a decrease in porosity caused by phenomena such as pore structure collapse.

[0026] Furthermore, the solution of the compound represented by formula (II) is an alcohol solvent solution of the compound represented by formula (II), and even further, the alcohol solvent includes ethanol.

[0027] Furthermore, the mass concentration of the solution of the compound shown in formula (II) is 3%-7%.

[0028] Furthermore, the soaking time should be controlled to be 5-24 hours.

[0029] In some embodiments of the present invention, the drying is carried out under a gradient temperature treatment, which includes: treatment at 35-45°C for 10-14 hours, treatment at 55-65°C for 6-10 hours, and treatment at 75-85°C for 2-6 hours.

[0030] In some embodiments of the present invention, the heat treatment is controlled to be carried out under a protective atmosphere, further comprising a nitrogen atmosphere or an inert gas atmosphere.

[0031] In some embodiments of the present invention, the heat treatment is controlled to be carried out at 1200-1600°C.

[0032] According to some specific aspects of the present invention, the heat treatment is controlled to be carried out at temperatures of 1200°C, 1250°C, 1300°C, 1350°C, 1400°C, 1450°C, 1500°C, 1550°C, and 1600°C.

[0033] In some embodiments of the present invention, the heat treatment holding time is controlled to be 1-5 hours.

[0034] In some embodiments of the present invention, the amine compound includes polyethyleneimine.

[0035] In some embodiments of the present invention, during the preparation of the silicon carbide aerogel-based carbon dioxide adsorbent material, the silicon carbide aerogel is impregnated in an amine compound solution to prepare the silicon carbide aerogel-based carbon dioxide adsorbent material.

[0036] Furthermore, the amine compound solution is an amine compound alcohol solution, which is prepared by dispersing the amine compound in an alcohol solvent; even further, the alcohol solvent includes ethanol.

[0037] In some embodiments of the present invention, the mass concentration of the amine compound alcohol solution is 10%-30%.

[0038] Furthermore, the impregnation is controlled to be carried out at a temperature of 10-60℃, for example, at temperatures of 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, and 60℃.

[0039] In some embodiments of the present invention, the silicon carbide aerogel has a three-dimensional network structure, which includes a multi-level pore structure.

[0040] Another technical solution provided by the present invention: a silicon carbide aerogel-based carbon dioxide adsorbent material prepared by the preparation method of the silicon carbide aerogel-based carbon dioxide adsorbent material described above.

[0041] Another technical solution provided by the present invention: the application of the above-mentioned silicon carbide aerogel-based carbon dioxide adsorption material in the preparation of carbon dioxide adsorption equipment.

[0042] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: Addressing the problems of low CO2 adsorption capacity, slow adsorption rate, and irreversible degradation of adsorption performance in existing amine adsorbents, this invention innovatively provides a novel silicon carbide aerogel-based CO2 adsorbent material and its preparation method. This method involves first preparing a wet gel using specific siloxanes and carbonizable organic compounds, then treating the surface with hydrophobicity and drying it to form a dry gel. Following heat treatment, a silicon carbide aerogel is generated. A higher molecular weight amine compound is then loaded onto the silicon carbide aerogel. Practice has shown that the silicon carbide aerogel-based CO2 adsorbent material prepared in this way (also known as an amine-functionalized silicon carbide aerogel adsorbent) possesses advantages such as high CO2 adsorption capacity, ultrafast adsorption kinetics, excellent thermal stability, and low regeneration energy consumption. Furthermore, (1) this invention achieves synergistic effects between the multi-level pore structure of the carrier and the dispersion of amines, thereby simultaneously improving adsorption kinetics and capacity: The silicon carbide aerogel carrier prepared by this invention has a unique multi-level pore structure with both macropores and mesopores. The interconnected macropores provide a macroscopic channel for the rapid diffusion of CO2 molecules, while the abundant mesopores create a huge specific surface area. The high molecular weight amines loaded on this structure can have their long chains fully extended and attached to the surface of the mesopores, thus achieving a high density and uniform distribution of amines. This synergistic combination of "rapid mass transfer through macropores and high amine loading through mesopores" effectively solves the technical contradiction that high loading often leads to slow mass transfer in traditional adsorbents, enabling the material to simultaneously possess high CO2 adsorption capacity and ultrafast adsorption kinetics.

[0043] (2) This invention achieves efficient thermal management and low-energy regeneration by synergistic effect between the intrinsic high thermal conductivity of the carrier and the amine reaction sites: The inherent high thermal conductivity of silicon carbide material, combined with its three-dimensional continuous network, endows the carrier with excellent thermal transport capabilities. In the CO2 adsorption and desorption cycle, the heat of reaction generated on the amine active sites can be rapidly discharged and homogenized through this thermally conductive network. This synergistic effect avoids the local accumulation of heat of reaction at the amine sites, which not only protects the stability of the amine functional groups and prevents them from failing due to overheating, but also significantly improves the thermal energy utilization efficiency, thereby greatly reducing the energy consumption required for the material regeneration and desorption process.

[0044] (3) This invention achieves synergy between the rigid framework of the carrier and the long-chain structure of the amine, endowing the material with excellent cycle stability: The silicon carbide ceramic framework has excellent chemical and mechanical stability. The long chains of higher molecular weight amine compounds are firmly anchored to this rigid network through strong physical entanglement and possible surface interactions, forming a composite structure similar to "rigid and flexible". This synergistic combination mechanism fundamentally overcomes the disadvantages of small molecule amines being volatile and easily lost, ensuring that the active components of the adsorbent remain stable and structurally intact during long-term and repeated adsorption-desorption cycles, exhibiting a significantly extended service life.

[0045] (4) This invention achieves comprehensive performance optimization, meeting the core requirements of efficient carbon capture: Based on multi-level synergistic effects, the composite adsorbent obtained by this invention achieves optimized balance in key performance aspects: it possesses high adsorption capacity based on high amine loading and abundant pore volume; rapid adsorption / desorption kinetics benefiting from optimized pore channels and rapid thermal management; and long cycle life and low operating energy consumption due to its stable composite structure and stable chemical properties. These comprehensive advantages make this material very suitable for carbon dioxide capture scenarios with stringent requirements for adsorption efficiency, operating costs, and long-term stability. Detailed Implementation

[0046] The above-mentioned solution will be further described below with reference to specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0047] Unless otherwise specified in the following examples, all raw materials are commercially available or prepared by conventional methods in the art.

[0048] Example 1: This example provides a silicon carbide aerogel-based carbon dioxide adsorbent material and its preparation method. The preparation method includes: (1) Preparation of wet gel: By mass percentage, silicon source (tetraethyl orthosilicate, content 22%), carbon source (phenolic resin, content 16%), solvent (anhydrous ethanol, content 53%) and water (content 9%) were mixed. The pH was adjusted to 3 with hydrochloric acid catalyst of about 37% mass concentration under stirring, and the reaction was carried out in a water bath at 50°C to form a uniform sol. Then, it was allowed to stand to gel, and then aged with anhydrous ethanol at 50°C for 24 hours.

[0049] (2) Hydrophobization and drying to prepare dry gel: The wet gel obtained according to step (1) was immersed in an ethanol solution containing trimethylchlorosilane (mass concentration of 5%) for surface hydrophobization treatment for 12 hours. Subsequently, the gel was subjected to gradient drying at 40℃ (drying time of 12h), 60℃ (drying time of 8h) and 80℃ (drying time of 4h) to obtain a blocky organic-inorganic hybrid dry gel.

[0050] (3) Preparation of the carrier: The dry gel was placed in a tube furnace and heated to 1500°C at a rate of 5°C / min under an argon protective atmosphere. The temperature was maintained at this temperature for 2 hours. After cooling with the furnace, a carrier with a three-dimensional network structure, silicon carbide aerogel, was obtained.

[0051] (4) Amine functionalization: The above silicon carbide aerogel was immersed in a 20% (w / w) ethanol solution of linear polyethyleneimine (molecular weight 10,000, purchased from Sigma-Aldrich, catalog number 765090) for 12 hours at 25°C. After removal, it was vacuum dried at 60°C for 4 hours to obtain a silicon carbide aerogel-based carbon dioxide adsorbent material, denoted as ADS-1.

[0052] Example 2: This example provides a silicon carbide aerogel-based carbon dioxide adsorbent material and its preparation method. The preparation method is basically the same as in Example 1, except that in step (1), the mass percentage of each component is as follows: silicon source (tetraethyl orthosilicate) content is 32%, carbon source (phenolic resin) content is 12%, solvent (anhydrous ethanol) content is 48%, and water content is 8%. The final silicon carbide aerogel-based carbon dioxide adsorbent material is designated as ADS-2.

[0053] Example 3: This example provides a silicon carbide aerogel-based carbon dioxide adsorbent material and its preparation method. The preparation method is basically the same as in Example 1, except that in step (1), the mass percentage of each component is as follows: silicon source (tetraethyl orthosilicate) content is 18%, carbon source (phenolic resin) content is 23%, solvent (anhydrous ethanol) content is 50%, and water content is 9%. The final silicon carbide aerogel-based carbon dioxide adsorbent material is designated as ADS-3.

[0054] Example 4: This example provides a silicon carbide aerogel-based carbon dioxide adsorbent material and its preparation method. The preparation method is basically the same as in Example 1, except that in step (4), the number average molecular weight of the polyethyleneimine used is 800. The final silicon carbide aerogel-based carbon dioxide adsorbent material is designated as ADS-4.

[0055] Comparative Example 1: This example provides a silicon carbide aerogel-based carbon dioxide adsorbent material and its preparation method. The preparation method is basically the same as in Example 1, except that in step (4), polyethyleneimine is replaced with a composition of tetraethylenepentamine (TEPA) and diethanolamine (DEA) in a mass ratio of 1:1, and the mass concentration of the ethanol solution of the composition is kept at 20%. The resulting sample is denoted as C-1.

[0056] Comparative Example 2: This example provides an adsorbent material and its preparation method, the preparation method comprising: (1) Preparation of amine-containing wet gel: By mass percentage, silicon source (tetraethyl orthosilicate, 22%), carbon source (phenolic resin, 16%), solvent (anhydrous ethanol, 53%), and water (9%) were mixed, and the pH was adjusted to 3 with hydrochloric acid of approximately 37% by mass. Under stirring in a water bath at 50°C, a 20% linear polyethyleneimine (molecular weight 10,000, purchased from Sigma-Aldrich, catalog number 765090) ethanol solution was added directly to this mixture, the amount of which was equivalent to that used in Example 1. Stirring was continued for 1 hour to allow PEI to be evenly dispersed in the sol, and then allowed to stand to gel, resulting in a wet gel containing PEI.

[0057] (2) Drying and carbonization (without hydrophobic pretreatment): The wet gel obtained in step (1) was directly subjected to gradient drying (40℃ (drying time for 12h), 60℃ (drying time for 8h) and 80℃ (drying time for 4h)) to obtain an amine-containing dry gel. Subsequently, this dry gel was placed in a tube furnace and heated to 1500℃ at a rate of 5℃ / min under argon protection, and held at this temperature for 2 hours, followed by furnace cooling. The resulting sample was designated C-2.

[0058] Comparative Example 3: This example provides an adsorbent material and its preparation method. The preparation method is basically the same as that in Example 1, except that in step (2), the hydrophobic treatment is omitted and gradient drying is carried out directly on the basis of step (1).

[0059] In this case, the gel underwent severe shrinkage during the drying process (linear shrinkage rate >50%), ultimately resulting in a cracked, dense block, failing to produce a porous and fluffy dry gel. After subjecting this dry gel to carbothermic reduction treatment under the same conditions, the resulting product was a dense silicon carbide ceramic block, rather than an aerogel with a three-dimensional network structure. Due to its extremely low porosity and small specific surface area, effective amine loading was not possible subsequently. This demonstrates that surface hydrophobication treatment is a crucial step in the drying process to obtain a dry gel with high porosity, as it reduces capillary forces and prevents the collapse of the gel network during drying.

[0060] Comparative Example 4: This example provides an adsorbent material and its preparation method, which is basically the same as in Example 1, except that in step (1), the mass percentage of each component is as follows: silicon source (tetraethyl orthosilicate) content 10%, carbon source (phenolic resin) content 30%, solvent (ethanol) content 50%, and water content 10%. The resulting sample is denoted as C-3.

[0061] Performance testing: The material was placed in a fixed-bed adsorption apparatus for carbon dioxide adsorption-desorption performance testing. The fixed-bed reactor was a high-temperature resistant glass tube with an inner diameter of 5 mm, an outer diameter of 10 mm, and a length of 200 mm, equipped with a precision temperature control device on the outside. The reaction temperature deviation was less than ±0.5℃, and both ends of the reactor were filled with ultrafine glass wool to reduce adsorbent loss during the test.

[0062] Take 1.0 g of the adsorbent material (also called adsorbent) obtained in Examples 1-4, Comparative Examples 1-2, and Comparative Example 4, and uniformly fill it into a fixed-bed reactor. First, the adsorbent is heated at 100 mL / min. -1 The adsorbent was pretreated by heating at 373 K for 1 hour under a high-purity N2 atmosphere to remove impurities. After the reactor cooled to the required experimental temperature (348 K) and stabilized, the gas path was switched to 100 mL / min. -1 A CO2 adsorption experiment was conducted using simulated flue gas containing 15% CO2. The CO2 concentration at the fixed bed outlet was measured using a CO2 analyzer. Adsorption saturation was indicated when the outlet CO2 concentration equaled the inlet concentration. A breakthrough curve was plotted based on the change in CO2 concentration at the fixed bed outlet over different time periods. The CO2 adsorption capacity was calculated by integrating the area under the breakthrough curve using conditions such as CO2 inlet concentration and flow rate. The integral calculation formula is shown below.

[0063] ; Where Q is the amount of CO2 adsorbed by the adsorbent (mmol·g) -1 m is the mass of the adsorbent (g), and v is the inlet gas flow rate (mL·min). -1C0 represents the CO2 concentration at the inlet of the fixed-bed reactor (vol.%), C represents the CO2 concentration at the outlet of the fixed-bed reactor (vol.%), t represents the adsorption time (s), P represents the experimental operating pressure (kPa), T represents the experimental temperature (K), and R represents the gas constant (8.314 J·mol⁻¹). -1 ·K -1 ).

[0064] Desorption performance and cycling stability were then tested. After adsorption was complete, the gas flow was switched to 100 mL / min. -1 The CO2 was heated to 373 K for desorption experiments. When the CO2 concentration at the fixed bed outlet was 0, it proved that the adsorbent had been regenerated. This CO2 adsorption / desorption experiment was repeated multiple times to examine the cyclic stability of the adsorbent.

[0065] (1) Data on the adsorption capacity and cycle stability of different adsorbent materials are shown in Table 1.

[0066] Table 1

[0067] (2) Statistics on the adsorption amount of different adsorbent materials within 1 minute, see Table 2 for details.

[0068] Table 2

[0069] From the above, we can see that: The adsorbent material in Example 1 exhibits a high CO2 adsorption capacity, reaching approximately 88% of its saturated adsorption capacity within one minute. Furthermore, after 10 adsorption-desorption cycles, its capacity retention remains greater than 94%. Analysis suggests that its superior performance is attributed to the optimized formulation, which results in a carrier with a balanced macroporous / mesoporous ratio and a stable framework structure. This provides high loading space and good dispersibility for the PEI, while simultaneously ensuring an efficient CO2 mass transfer pathway.

[0070] The CO2 adsorption capacity of the adsorbent material in Example 2 was slightly lower than that in Example 1. Analysis suggests this is because the higher proportion of silicon source resulted in a denser silicon carbide framework, leading to a reduction in the specific surface area and total pore volume of the carrier compared to ADS-1, thus limiting the maximum PEI loading. However, the higher SiC content improved the material's thermal stability.

[0071] Under the same testing conditions, the adsorbent material ADS-3 in Example 3 exhibited the highest CO2 adsorption capacity, reaching 6.2 mmol / g, but the adsorption amount reached approximately 80% of the saturation capacity within 1 minute. Analysis suggests that its high capacity is attributed to the abundant carbon source generating a carbon framework with larger pore volumes, and the support formed after carbothermic reduction being able to load more PEI. The slightly slower kinetics may be related to the fact that some mesopores were filled with highly loaded PEI, resulting in a slightly more complex mass transfer pathway.

[0072] Under the same test conditions, the CO2 adsorption capacity of the adsorbent material ADS-4 in Example 4 was 5.6 mmol / g, and the adsorption capacity reached approximately 89% of the saturation capacity within 1 minute. Its adsorption kinetics were the fastest, which is attributed to the fact that the shorter and lower viscosity of the lower molecular weight PEI chains allow for easier penetration and uniform dispersion within the smaller pores of the support, resulting in higher accessibility to amine sites. However, its long-term cycling stability is expected to be lower than that of the high molecular weight PEI (ADS-1) due to weaker chain entanglement and anchoring effects.

[0073] Under the same test conditions, the initial CO2 adsorption capacity of adsorbent C-1 in Comparative Example 1 was 5.9 mmol / g, similar to that of ADS-1 in Example 1, indicating that small molecule amines have high activity. However, after 10 adsorption-desorption cycles, its capacity retention was only ~68%, far lower than that of ADS-1 (>94%). Analysis suggests that this is because small molecule amines such as TEPA / DEA bind to the silicon carbide support primarily through physical adsorption, and are easily desorbed and lost under temperature cycling and gas scouring. This comparison demonstrates that using high molecular weight PEI to achieve strong anchoring is crucial for long-term cycling stability.

[0074] Testing revealed that the adsorbent C-2 in Comparative Example 2 showed almost no CO2 adsorption capacity (<0.5 mmol / g). Analysis suggests this is because the PEI completely decomposed during the high-temperature carbonization process, and the organic amine functional groups could not withstand the high temperatures required for silicon carbide synthesis, resulting in the absence of effective amine functional groups in the support. This result directly verifies the necessity of the step-by-step strategy of "preparing a high-temperature resistant support first, then loading the amine at a low temperature" employed in this invention.

[0075] In Comparative Example 4, the CO2 adsorption capacity was only 3.0 mmol / g. Analysis suggests this is because the excessively high carbon source and insufficient silicon source resulted in a large amount of amorphous carbon remaining after the carbothermic reduction reaction. Furthermore, the SiC framework is discontinuous, has low strength, and is brittle. Simultaneously, the residual carbon easily clogs the pores, affecting mass transfer and amine loading. Therefore, an unbalanced raw material ratio leads to structural defects in the support, severely impacting the overall performance of the final adsorbent.

[0076] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0077] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for preparing a silicon carbide aerogel-based carbon dioxide adsorbent material, characterized in that, The preparation method includes: The compound shown in formula (I), the carbonizable organic material, and the solvent are mixed to form a wet gel; the mass ratio of the compound shown in formula (I) to the carbonizable organic material is 1:0.25-1.

8. In the formula, R1, R2, R3, and R4 are independently selected from C. 1-6 alkyl; The wet gel is subjected to a surface hydrophobic treatment and then dried to prepare a dry gel; The dry gel is heat-treated to generate silicon carbide aerogel. An amine compound with a number average molecular weight of 600-100,000 was loaded onto the silicon carbide aerogel by a loading method.

2. The method for preparing silicon carbide aerogel-based carbon dioxide adsorbent material according to claim 1, characterized in that, R1, R2, R3, and R4 are independently selected from methyl, ethyl, propyl, or butyl; and / or, the mass ratio of the compound represented by formula (I) to the carbonizable organic material is 1:0.35-1.5; and / or, the carbonizable organic material includes phenolic resin, furfural resin, asphalt, or sugar compounds.

3. The method for preparing silicon carbide aerogel-based carbon dioxide adsorbent material according to claim 1, characterized in that, The solvent is composed of water and alcohol solvents; Furthermore, the mass ratio of water to alcohol solvent is 1:2.5-13, and even more specifically 1:4-8; Furthermore, the alcohol solvent includes methanol, ethanol, or propanol; And / or, The wet gel, by weight percentage, comprises 15%-35% of the compound shown in formula (I), 10%-25% of a carbonizable organic compound, 40%-65% of an alcohol solvent, and 5%-15% of water; and / or, During the preparation of the wet gel, acid is added to adjust the pH of the system, and further, the pH of the system is adjusted to 2-4.

4. The method for preparing silicon carbide aerogel-based carbon dioxide adsorbent material according to claim 1, characterized in that, The preparation process of the wet gel includes: The compound shown in formula (Ⅰ), the carbonizable organic compound and the solvent are mixed, and the pH of the system is adjusted to 2-4 with acid under stirring. A sol is formed under the first heating condition, and it is allowed to stand to gel. Then, it is aged with an alcohol solvent under the second heating condition to obtain a wet gel. Furthermore, the heating temperatures of the first heating condition and the second heating condition are controlled to be 40-60℃ respectively; Furthermore, the alcohol solvent used in the aging process includes ethanol.

5. The method for preparing silicon carbide aerogel-based carbon dioxide adsorbent material according to claim 1, characterized in that, The surface hydrophobic treatment process includes: The wet gel was immersed in a solution of the compound shown in formula (II) to obtain a hydrophobic gel. In the formula, R5, R6, and R7 are independently selected from C. 1-3 alkyl; Furthermore, the solution of the compound shown in formula (II) is an alcohol solvent solution of the compound shown in formula (II), and even further, the alcohol solvent includes ethanol; Furthermore, the mass concentration of the solution of the compound shown in formula (II) is 3%-7%; Furthermore, the soaking time should be controlled to be 5-24 hours.

6. The method for preparing silicon carbide aerogel-based carbon dioxide adsorbent material according to claim 1, characterized in that, The drying is carried out under a gradient temperature treatment, which includes: treatment at 35-45℃ for 10-14 hours, treatment at 55-65℃ for 6-10 hours, and treatment at 75-85℃ for 2-6 hours; and / or, The heat treatment is controlled to be carried out under a protective atmosphere, further comprising a nitrogen atmosphere or an inert gas atmosphere; and / or, The heat treatment is controlled to be carried out at 1200-1600°C; and / or, The heat treatment holding time is controlled to be 1-5 hours.

7. The method for preparing silicon carbide aerogel-based carbon dioxide adsorbent material according to claim 1, characterized in that, The amine compound includes polyethyleneimine; and / or, In the preparation process of the silicon carbide aerogel-based carbon dioxide adsorbent material, the silicon carbide aerogel is immersed in an amine compound solution to prepare the silicon carbide aerogel-based carbon dioxide adsorbent material. Further, the amine compound solution is an amine compound alcohol solution, which is prepared by dispersing the amine compound in an alcohol solvent; even further, the alcohol solvent includes ethanol, and the mass concentration of the amine compound alcohol solution is 10%-30%; Furthermore, the impregnation is carried out at a temperature of 10-60°C.

8. The method for preparing silicon carbide aerogel-based carbon dioxide adsorbent material according to claim 1, characterized in that, The silicon carbide aerogel has a three-dimensional network structure, which includes a multi-level pore structure.

9. A silicon carbide aerogel-based carbon dioxide adsorbent prepared by the preparation method of the silicon carbide aerogel-based carbon dioxide adsorbent according to any one of claims 1-8.

10. The application of the silicon carbide aerogel-based carbon dioxide adsorbent material according to claim 9 in the preparation of carbon dioxide adsorption equipment.

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