Potassium-based low-temperature CO2 adsorption material with core-shell structure as well as preparation method and application of potassium-based low-temperature CO2 adsorption material

Abstract

The invention discloses a potassium-based low-temperature CO2 adsorption material with a core-shell structure and a preparation method and application, and belongs to the technical field of industrial flue gas treatment.The method comprises the steps that aluminum oxide powder is dissolved in water, after ultrasonic dispersion, potassium carbonate powder is added, the mixture is stirred and mixed to be uniform, and potassium carbonate / aluminum oxide composite powder is obtained through a hydrothermal reaction, filtering and drying; and dissolving polyetherimide in ethanol, adding the potassium carbonate / aluminum oxide composite powder, carrying out ultrasonic dispersion uniformly, and carrying out solvothermal reaction, filtration and drying to obtain the potassium-based low-temperature CO2 adsorption material with the core-shell structure. Potassium carbonate is used as an active component and effectively adsorbs CO2; alumina powder is used as a carrier to facilitate potassium carbonate dispersion and adsorption processes; the PEI shell layer can prevent SO2 from diffusing to the inner core and protect the potassium carbonate active component from being poisoned by SO2; the core-shell structure design enables CO2 to reach the potassium carbonate of the inner core through the PEI shell, so that efficient adsorption is realized, and meanwhile, poisoning of SO2 to active components is avoided.

Description

Technical Field

[0001] This invention belongs to the field of industrial flue gas treatment technology, specifically relating to potassium-based low-temperature CO2 adsorption materials with core-shell structures, their preparation methods, and applications. Background Technology

[0002] Solid-state adsorption for CO2 capture is an emerging carbon capture strategy characterized by its adaptability, lack of corrosion, and absence of secondary pollution. Low-temperature solid-state adsorption, in particular, boasts low energy consumption, low construction costs, and simple operation, making it suitable for most thermal power units. It can fully utilize the unit's low-grade heat source to drive the carbon capture reaction, reducing energy consumption. However, low-temperature solid-state adsorption also has drawbacks, including low adsorption capacity, large footprint, and susceptibility to poisoning by impurities under actual flue gas conditions. In actual flue gas from coal-fired units, small amounts of SO2 and NO are present. x Since SO2 has very similar physicochemical properties to CO2, various adsorption materials cannot specifically adsorb CO2 without adsorbing SO2. At the same time, SO2 adsorption is often irreversible. Therefore, under actual flue gas conditions, SO2 will continuously poison carbon adsorption materials.

[0003] CN117443132A discloses an adsorption system and method for capturing low-concentration CO2 industrial flue gas. This invention achieves enrichment and concentration of low-concentration CO2 through a combination of a catalytic CO pretreatment unit, a flue gas flow distribution unit, a heat exchange unit, a waste heat distribution unit, a primary temperature-switching adsorption unit, and a secondary pressure-switching adsorption unit. However, the formulation and preparation process of the adsorbent in the primary temperature-switching adsorption unit and the secondary pressure-switching adsorption unit still need further optimization to improve the adsorption capacity and selectivity of the adsorbent. CN118059830A proposes an adsorption material and its preparation method for capturing low-concentration CO2 in the air. This invention uses an inexpensive macroporous adsorption resin as a carrier to load organic amine active components, improving adsorption capacity while reducing the cost of the adsorption material. However, the material and structure of the adsorption matrix still need further optimization to improve the adsorption capacity and adsorption rate of the adsorption material.

[0004] Existing low-temperature solid adsorbent materials are used in the actual flue gas composition of coal-fired power units, which contains small amounts of SO2 and NO. xIn harsh environments, CO2 is easily poisoned by SO2, leading to a decline in adsorption performance and affecting the material's cycle stability and service life. Existing materials have low adsorption capacity and selectivity at low temperatures and are easily poisoned by impurities in practical applications, requiring a large footprint. The adsorbent formulations and preparation processes used in existing technologies still need further optimization to improve the adsorption capacity and selectivity. The materials and structures of the adsorption matrix in existing technologies also need further optimization to improve the adsorption capacity and adsorption rate. Developing highly active and durable industrial flue gas-adaptive adsorbents is a key step in achieving carbon capture in flue gas from coal-fired power plants. Such materials not only need to possess high CO2 adsorption capacity and good thermal stability but also need to resist poisoning by impurities such as SO2, demonstrating good potential for industrial applications. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a potassium-based low-temperature CO2 adsorption material with a core-shell structure, its preparation method and application, so as to solve the technical problem that existing low-temperature solid adsorption materials are easily poisoned by SO2 under actual flue gas conditions, resulting in a decline in adsorption performance.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a method for preparing a potassium-based low-temperature CO2 adsorbent material with a core-shell structure, comprising: 1) Dissolve alumina powder in water, disperse it ultrasonically, add potassium carbonate powder and stir to mix evenly. After hydrothermal reaction, filter and dry to obtain potassium carbonate / alumina composite powder. 2) After dissolving polyetherimide in ethanol, potassium carbonate / alumina composite powder is added and ultrasonically dispersed evenly. After solvothermal reaction, filtration and drying, potassium-based low-temperature CO2 adsorbent material with core-shell structure is obtained.

[0007] Preferably, in step 1), the ratio of alumina powder, potassium carbonate powder and water is (4~16) g: 8 g: 18 mL.

[0008] Preferably, in step 1), the stirring and mixing time is 1.5-2 hours; the hydrothermal reaction temperature is 110-120°C; and the hydrothermal reaction time is 5-6 hours.

[0009] Preferably, in step 2), the ratio of polyetherimide, ethanol, and potassium carbonate / alumina composite powder is (1~3) g: 10 mL: 10 g.

[0010] Preferably, in step 2), the temperature of the solvothermal reaction is 80-90℃; the time of the solvothermal reaction is 6-8h.

[0011] The present invention also discloses a potassium-based low-temperature CO2 adsorbent material with a core-shell structure, which is prepared by the above-mentioned method for preparing potassium-based low-temperature CO2 adsorbent material with a core-shell structure; the core of the potassium-based low-temperature CO2 adsorbent material with a core-shell structure is an alumina support loaded with potassium carbonate, and the outer shell is a polyetherimide coating layer.

[0012] Preferably, the polyetherimide coating layer accounts for 10%-30% of the total mass of the potassium-based low-temperature CO2 adsorbent material with a core-shell structure; the melt flow rate of the polyetherimide is 9-10 g / 10 min.

[0013] The present invention also discloses the application of the potassium-based low-temperature CO2 adsorbent material with core-shell structure prepared by the above-mentioned method in industrial flue gas treatment.

[0014] Preferably, a potassium-based low-temperature CO2 adsorbent material with a core-shell structure is packed into a fixed-bed reactor, and simulated industrial flue gas is introduced to carry out the adsorption reaction; the flow rate of the simulated industrial flue gas is 100-300 mL / min; the adsorption temperature is 50-70℃, and the desorption temperature is 140-160℃.

[0015] Preferably, after 10 cycles of adsorption-desorption, the adsorption capacity decay rate is less than 10%.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for preparing a potassium-based low-temperature CO2 adsorbent with a core-shell structure. Potassium carbonate is used as the active ingredient, and alumina powder is used as the carrier. By adding polymeric additives, the adsorbent's resistance to poisoning is improved without affecting its original adsorption capacity. This effectively solves the problem of existing materials failing to adsorb small amounts of SO2 and NO in actual flue gas from coal-fired power plants. xThe problem of SO2 poisoning in the environment is significantly improved, enhancing the material's cycle stability and service life. By modifying the adsorbent powder with a polyetherimide (PEI) shell, a core-shell structure adsorbent is formed. The PEI shell can specifically bind SO2, effectively preventing the potassium-based adsorbent from being poisoned and deactivated by SO2 under actual flue gas conditions, thus improving the material's stability in complex flue gas environments. The prepared potassium-based low-temperature adsorbent material exhibits good adsorption activity in the low-temperature adsorption range, and after 10 cycles of adsorption-desorption experiments under simulated actual flue gas conditions, the adsorption capacity decreases by less than 10%, demonstrating excellent performance and overcoming the shortcomings of existing materials in terms of low adsorption capacity and selectivity under low-temperature conditions. The preparation process is simple and controllable, the raw materials are readily available, and the cost is low, making it suitable for industrial production. This solves the problem of needing further optimization of adsorbent formulations and preparation processes in existing technologies. The core-shell structure design is reasonable, ensuring both high-temperature thermal stability and low-temperature adsorption activity, effectively solving the problem of needing further optimization of adsorption matrix materials and structures in existing technologies.

[0017] This invention also discloses a potassium-based low-temperature CO2 adsorbent material with a core-shell structure. The core of this material is an alumina support loaded with potassium carbonate, and the outer shell is a polyetherimide coating layer. The core and shell are functionally independent yet synergistic. The alumina support loaded with potassium carbonate in the core disperses the active potassium carbonate component through the high specific surface area of ​​the alumina, enhancing the carbon dioxide adsorption capacity. The polyetherimide coating layer in the outer shell selectively binds sulfur dioxide through polar groups in its molecular chain, forming a physical barrier layer that prevents poisoning components from penetrating into the core. During adsorption, carbon dioxide passes through the outer shell layer to reach the active potassium carbonate sites in the core for adsorption, while sulfur dioxide is confined to the outer shell layer, preventing irreversible reactions with the core. During desorption, the outer shell structure remains stable at high temperatures, ensuring that the active components in the core are not destroyed. This effectively solves the problem of easy deactivation of low-temperature adsorbent materials in sulfur-containing flue gas and maintains the long-term stability of the adsorption capacity. The selective retention of sulfur dioxide by the outer shell avoids chemical poisoning of the active component potassium carbonate. The synergistic effect of the core and the outer shell ensures the material's recyclability in complex flue gas environments, while maintaining its high-efficiency adsorption capacity for carbon dioxide.

[0018] This invention also discloses the preparation method of the aforementioned potassium-based low-temperature CO2 adsorbent with a core-shell structure, and its application in industrial flue gas treatment. This material achieves selective separation of CO2 and SO2 through its core-shell structure design. The polyetherimide shell preferentially adsorbs SO2 and forms a stable bond, preventing it from contacting the active sites of the potassium carbonate core; CO2 diffuses through the shell to the core and undergoes chemisorption with potassium carbonate. In a fixed-bed reactor, the high adsorption efficiency of the material is maintained by low-temperature conditions during the adsorption stage, while CO2 release and material regeneration are achieved by moderately raising the temperature during the desorption stage. Flow rate control optimizes the gas-solid contact time, avoiding incomplete adsorption due to excessively fast airflow or reduced treatment efficiency due to excessively slow airflow. This solves the problem of decreased adsorption performance caused by SO2 poisoning in industrial flue gas, achieving highly efficient and selective adsorption of CO2 in complex flue gas environments. The material maintains a stable adsorption capacity during recycling, avoiding the rapid failure of traditional adsorbents due to sulfide accumulation. By synergistically controlling the adsorption and desorption temperatures, energy consumption is reduced while the service life of materials is extended, meeting the needs of continuous industrial flue gas treatment. Attached Figure Description

[0019] Figure 1 This is a cyclic stability test diagram of sample 1 prepared in Example 1 of the present invention; Figure 2 This is a cyclic stability test diagram of sample 5 prepared in Example 5 of the present invention; Figure 3 This is a cyclic stability test diagram of sample 6 prepared in Comparative Example 1 of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0022] Unless otherwise specified, all the technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0023] In this invention, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0024] Unless otherwise specified, the components or preferred components involved in this invention can be combined with each other to form new technical solutions.

[0025] In this invention, unless otherwise specified, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6~22" indicates that all real numbers between "6~22" have been listed in this document, and "6~22" is simply a shortened representation of these numerical combinations.

[0026] The "scope" disclosed in this invention can be in the form of a lower limit and an upper limit, and can be one or more lower limits and one or more upper limits, respectively.

[0027] In this invention, the term "and / or" as used herein refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0028] In this invention, unless otherwise stated, the various reactions or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0029] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0030] Potassium-based adsorbents stand out among low-temperature adsorbents due to their high adsorption capacity and readily available low cost. This invention uses potassium carbonate as the active ingredient and alumina powder as the carrier. By adding polymeric additives, the adsorbent's resistance to poisoning is improved without affecting its original adsorption capacity. This lays the foundation for future industrial applications.

[0031] This invention provides a method for preparing a potassium-based low-temperature CO2 adsorbent material with a core-shell structure. Alumina powder is dissolved in water and ultrasonically dispersed. Potassium carbonate powder is added and mixed, followed by a hydrothermal reaction to prepare a composite powder. A polyetherimide ethanol solution is then mixed with the composite powder and subjected to a solvothermal reaction to ultimately form the core-shell structured adsorbent material. Alumina powder acts as a porous carrier, forming a stable mesoporous structure through the hydrothermal reaction. Potassium carbonate, as the active component, is fixed to the carrier surface through a combination of mechanical stirring and hydrothermal crystallization, forming high-density adsorption sites. The polyetherimide coating layer forms a continuous film through a solvothermal reaction; its microporous structure between molecular chains allows carbon dioxide diffusion while blocking sulfur dioxide permeation. Ultrasonic dispersion is used to eliminate particle agglomeration and ensure uniform distribution of the material components. The hydrothermal reaction is controlled at 110-120℃ for 5-6 hours to promote the formation of a stable composite structure between potassium carbonate and alumina. The solvothermal reaction is carried out at 80-90℃ for 6-8 hours to allow the polyetherimide molecular chains to fully extend and coat the composite powder.

[0032] An alumina support undergoes a hydrothermal reaction to form a three-dimensional network structure, with potassium carbonate crystals embedded in its pores to form a highly active core. Polyetherimide, dissolved in ethanol, forms a dense coating layer of controllable thickness on the surface of the composite powder via a solvothermal reaction. This coating layer functions as a molecular sieve, allowing carbon dioxide molecules to penetrate and react with the potassium carbonate core, while larger sulfur dioxide molecules are blocked. During the preparation process, the controlled hydrothermal reaction temperature and time ensure the bonding strength between the support and the active component, while the solvothermal reaction parameters adjust the porosity and mechanical stability of the coating layer. The stepwise synthesis process avoids damage to the active sites during coating, achieving structural synergy between the core and shell layers.

[0033] Traditional adsorbent materials are mostly prepared using single physical mixing or simple impregnation methods, resulting in easy detachment of active components and a lack of a protective layer. This invention, through a core-shell structure design, establishes a physical barrier mechanism while maintaining high adsorption activity, overcoming the limitation of traditional materials that struggle to simultaneously achieve anti-poisoning performance and adsorption capacity. Compared to chemical modification methods, this physical barrier approach does not alter the chemical properties of the active components, ensuring the material's thermal stability. This enables stable operation of the adsorbent material in sulfur dioxide-containing flue gas environments, effectively preventing the active components from being poisoned and deactivated. The core-shell structure ensures efficient carbon dioxide adsorption, while the selective permeation mechanism of the shell extends the material's lifespan. The staged preparation process ensures a tight bond at the core-shell interface, maintaining the material's structural integrity during cyclic adsorption-desorption. While maintaining the original adsorption performance, it significantly improves the material's environmental adaptability and cyclic stability.

[0034] The ratio of alumina powder, potassium carbonate powder, and water is (4~16) g: 8 g: 18 mL. Alumina powder serves as the carrier material; this range balances the carrier's loading capacity for the active ingredient while avoiding dilution of active sites due to excessive carrier. Potassium carbonate powder serves as the active ingredient; this dosage ensures a uniform suspension system during ultrasonic dispersion. Water serves as the reaction medium, satisfying the liquid phase environment required for the hydrothermal reaction while avoiding excessive water consumption that would increase subsequent drying energy consumption. Existing low-temperature adsorption material preparation processes often neglect the quantitative ratio between the carrier and the active ingredient, leading to uneven dispersion of the active ingredient or excessive carrier coverage of active sites. This invention, by limiting the precise ratio of alumina, potassium carbonate, and water, ensures a geometric match between the carrier pores and the active ingredient particles, allowing potassium carbonate to be uniformly distributed on the alumina surface and avoiding localized agglomeration or carrier waste. This invention solves the problem of uneven dispersion caused by improper ratio of carrier to active ingredient, enabling potassium carbonate particles to form a monolayer dispersion structure on the alumina surface; it optimizes the mass transfer efficiency of the hydrothermal reaction system, shortens the time for the reaction to reach equilibrium; and it improves the batch consistency of the composite powder, avoiding unstable adsorption performance caused by fluctuations in material ratio.

[0035] During the preparation process, the stirring and mixing time was set to 1.5-2 hours, the hydrothermal reaction temperature was controlled at 110-120℃, and the hydrothermal reaction time was maintained at 5-6 hours. Stirring and mixing ensured uniform dispersion of the materials in a liquid environment through mechanical stirring. Extending the stirring time allowed for sufficient contact between the alumina powder and potassium carbonate, forming a stable suspension system. The hydrothermal reaction temperature of 110-120℃ promoted the chemical bonding between the alumina support and potassium carbonate. The 5-6 hour reaction time ensured sufficient reaction while preventing damage to the support structure due to over-reaction. During the stirring and mixing stage, continuous mechanical force fully wetted the surface of the alumina particles and uniformly loaded the active potassium carbonate component, eliminating local agglomeration. Subsequently, in the 110-120℃ hydrothermal environment, the hydroxyl groups on the alumina surface chemically bonded with potassium carbonate, forming a stable composite interface structure. The 5-6 hour reaction time ensured the integrity of the internal pore structure of the support and allowed the active component to be fully embedded in the support framework. The synergistic effect of these three parameters results in a uniform distribution of active sites and a stable microstructure in the composite powder, providing a structural basis for the subsequent formation of the polyetherimide coating layer. Traditional preparation methods often employ short-time stirring or low-temperature hydrothermal conditions, leading to uneven dispersion of the active components or insufficient bonding between the carrier and the active components. This invention solves the problem of loose internal structure and susceptibility to SO2 corrosion in flue gas in the composite powder by optimizing the stirring time and reaction conditions, achieving a stable bond between the active components and the carrier. This effectively improves the structural stability of the composite powder, ensuring that the active components remain highly dispersed during adsorption, while also enhancing the material's resistance to SO2 poisoning, laying the foundation for performance optimization of core-shell structured adsorption materials.

[0036] The ratio of polyetherimide, ethanol, and potassium carbonate / alumina composite powder is (1~3) g: 10 mL: 10 g. Polyetherimide forms a selectively permeable membrane layer through interactions between molecular chains. Ethanol, with a fixed volume, ensures complete dissolution of the polyetherimide and uniform wetting of the composite powder. The potassium carbonate / alumina composite powder is a supported adsorption core formed through a hydrothermal reaction, achieving stable loading of the active component through chemical bonding between the hydroxyl groups on the alumina support surface and potassium carbonate. Traditional core-shell structure adsorption materials lack targeted optimization in the design of the ratio between the coating layer and the core, often resulting in a contradiction where an excessively thin coating layer leads to protection failure or an excessively thick coating layer hinders mass transfer. The random ratio method used in existing technologies cannot simultaneously achieve CO2 permeation efficiency and SO2 barrier performance, resulting in insufficient stability of the material under actual flue gas conditions. This invention achieves precise matching between the polyetherimide coating layer and the potassium carbonate / alumina composite powder, constructing an SO2 molecular barrier while maintaining unobstructed CO2 adsorption channels. This formulation design allows the coating layer to effectively block SO2 molecules from contacting the core active components without significantly increasing CO2 diffusion resistance, thus maintaining long-term stability of adsorption performance in complex flue gas environments.

[0037] The solvothermal reaction temperature is 80-90℃, and the reaction time is 6-8 hours. The solvothermal reaction temperature promotes the dissolution of polyetherimide in ethanol and its bonding reaction with the carrier surface, while avoiding polymer chain breakage due to high temperatures. The solvothermal reaction time allows the polyetherimide molecules to complete self-assembly and form a continuous coating layer. During this process, the synergistic effect of temperature and time ensures that the polymer shell completely coats the core while maintaining appropriate porosity to allow CO2 molecules to diffuse through, effectively preventing larger molecules such as SO2 from contacting the active components in the core. Traditional solvothermal methods for preparing coating materials often use reaction temperatures above 100℃, leading to thermal decomposition of the polymer material or collapse of the carrier structure. Existing low-temperature coating processes typically require reaction times exceeding 12 hours, resulting in reduced production efficiency. This invention, by optimizing the combination of temperature and time, shortens the production cycle while avoiding thermal damage to the material. A stable bond between the polyetherimide coating layer and the carrier particles was achieved. The resulting core-shell structure kept the CO2 adsorption channels open while blocking SO2 penetration. This allowed the material to maintain more than 90% of its initial adsorption capacity after 10 cycles in a sulfur-containing flue gas environment, solving the performance degradation problem of traditional potassium-based adsorbents caused by sulfide poisoning.

[0038] This invention further proposes a method for preparing a potassium-based low-temperature carbon dioxide adsorbent material with a core-shell structure. In the core, alumina serves as a carrier material, and potassium carbonate is uniformly dispersed on its surface and in its pores through a hydrothermal reaction, forming highly active adsorption sites. The outer shell, polyetherimide, forms a continuous and dense coating layer on the surface of the composite powder through a solvothermal reaction. This coating layer allows carbon dioxide molecules to diffuse through but retains sulfur dioxide through intermolecular forces. Traditional adsorbent materials use single components or simple mixtures, which cannot resist the erosion of poisoning components while maintaining high adsorption capacity. This invention achieves functional partitioning through a core-shell structure. The outer shell specifically treats poisoning components, while the core focuses on adsorbing the target gas, overcoming the performance limitations of single materials.

[0039] This invention further proposes that the polyetherimide coating layer constitutes 10%-30% of the total mass of the core-shell structured potassium-based low-temperature CO2 adsorbent material, with a melt flow rate of 9-10 g / 10 min for the polyetherimide. The mass percentage range of the polyetherimide coating layer is achieved by controlling the ratio of the coating layer thickness to the core carrier. This range ensures both the formation of a continuous physical barrier and the maintenance of the pore channels required for CO2 diffusion. The polyetherimide material with a melt flow rate of 9-10 g / 10 min exhibits specific solubility and molecular chain extension in ethanol solvent, directly affecting the balance between density and permeability during coating film formation. By limiting this ratio range, during the solvothermal reaction, the extended state of the polyetherimide molecular chains in ethanol forms a uniform coating on the surface of the composite powder, maintaining an effective permeation path for CO2 molecules while preferentially capturing SO2 molecules through chemisorption. Polyetherimide with a melt flow rate of 9-10 g / 10 min achieves optimal matching of molecular chain mobility and surface wettability under solvothermal reaction conditions at 80-90℃, ensuring a stable interfacial bond between the coating layer and the core carrier. Traditional adsorbent materials often employ single polymer coatings or fail to control melt flow parameters, leading to localized defects or over-densification of the coating layer. This invention, however, utilizes a gradient coating structure formed by polyetherimide with a specific melt flow rate to achieve a synergistic effect of selective SO2 capture and efficient CO2 diffusion. While maintaining CO2 adsorption capacity, it effectively blocks the poisoning effect of SO2 molecules on the core active components. The structural stability of the coating layer allows the adsorbent material to retain over 90% of its initial adsorption performance after 10 cycles. Furthermore, precise control of melt flow parameters ensures the repeatability of the coating process and the feasibility of large-scale production.

[0040] This invention further proposes the application of a core-shell structured potassium-based low-temperature CO2 adsorbent material in industrial flue gas treatment. The core is an alumina support loaded with potassium carbonate, and the outer shell is a polyetherimide coating layer. The core disperses the active sites of potassium carbonate through the high specific surface area of ​​the alumina, while the outer shell preferentially binds SO2 through the selective adsorption capacity of the polyetherimide, preventing SO2 from diffusing to the core and reacting with potassium carbonate, thus protecting the active ingredient from poisoning. The adsorption temperature is 50-70℃, allowing CO2 molecules to diffuse through the polyetherimide shell to the core for efficient adsorption while avoiding structural damage due to high temperatures. The desorption temperature is 140-160℃, allowing adsorbed CO2 to be released from the material while the polyetherimide shell remains stable, preventing high-temperature decomposition from affecting cycle performance. Simulated industrial flue gas flow rates of 100-300 mL / min ensure that the material maintains a stable adsorption capacity in actual industrial-scale applications. Traditional adsorbents do not employ a core-shell structure, allowing SO2 to react directly with the active ingredient, leading to irreversible deactivation. This invention, however, selectively blocks SO2 through the outer shell, significantly improving the material's stability in sulfur-containing flue gas. Existing technologies require higher temperatures for adsorbent regeneration, which can easily lead to carrier sintering or active ingredient decomposition. This invention, by optimizing the desorption temperature, maintains the material's structural integrity while ensuring regeneration efficiency.

[0041] This invention further proposes a technique for loading a potassium-based low-temperature carbon dioxide adsorbent with a core-shell structure into a fixed-bed reactor and introducing simulated industrial flue gas for adsorption. The flow rate of the simulated industrial flue gas is controlled at 100-300 mL / min, the adsorption temperature at 50-70℃, and the desorption temperature at 140-160℃. A porous distribution plate is installed inside the fixed-bed reactor to uniformly disperse the gas. This device can maintain a stable gas-solid interface, ensuring sufficient contact between the adsorbent and the flue gas. The flow rate of the simulated industrial flue gas is 100-300 mL / min, which ensures mass transfer efficiency while avoiding excessive flow rate that could cause adsorbent particles to be washed away by the gas flow. The adsorption temperature is controlled at 50-70℃, which matches the low-temperature adsorption characteristics of the potassium carbonate active component in the core-shell material, while avoiding increased energy consumption due to high temperatures. The desorption temperature is controlled at 140-160℃, which effectively releases the adsorbed carbon dioxide for material regeneration while avoiding damage to the polyetherimide outer shell structure due to excessive temperature. After loading a core-shell structured adsorbent material into a fixed-bed reactor, simulated flue gas flows through the adsorbent bed at a specific flow rate. At 50-70°C, carbon dioxide molecules diffuse through the polyetherimide outer shell to the core region, where they chemically adsorb potassium carbonate. Once adsorption is saturated, the temperature is increased to 140-160°C to desorb the adsorbed carbon dioxide, while the polyetherimide outer shell maintains its structural integrity. This combination of temperature parameters synergistically optimizes adsorption kinetics and thermodynamic processes, achieving efficient regeneration while maintaining the stability of the core-shell structure. Traditional adsorbent materials are prone to deactivation of active components due to sulfide penetration under the same operating conditions. This invention, however, uses a core-shell structure to prevent sulfides from contacting the core, while optimizing operating parameters to maintain the stability of the outer shell. Conventional technologies often use desorption temperatures above 180°C, which easily cause thermal decomposition of the polymer coating. This invention, by lowering the desorption temperature and extending the desorption time, ensures regeneration efficiency while avoiding damage to the material structure. This method effectively solves the problem of poor cycle stability of adsorbent materials caused by sulfide poisoning in industrial flue gas treatment, maintaining a stable adsorption capacity in the complex environment of sulfur-containing flue gas. The combination of operating parameters ensures that the core-shell structure material maintains the integrity of the outer shell during continuous adsorption-desorption, preventing sulfide diffusion inward, while simultaneously ensuring the full exposure and regeneration of carbon dioxide adsorption active sites.

[0042] This invention further proposes that the adsorption capacity decay rate is less than 10% after 10 cycles of adsorption-desorption. This is achieved by controlling the alternating operation of adsorption and desorption temperatures, and this parameter setting reflects the durability test standard of the material under actual working conditions. The adsorption capacity decay rate refers to the proportion of the material's adsorption capacity loss after a specified number of cycles, specifically calculated by comparing the difference between the initial adsorption capacity and the adsorption capacity after cycling. This indicator directly characterizes the strength of the material's resistance to poisoning. The polyetherimide coating layer in the core-shell structure forms a dense interface through a solvothermal reaction. Its melt flow rate parameter controls the structural stability of the coating layer during the high-temperature desorption process. This feature allows the outer shell layer to maintain its integrity during cycling and continuously perform its isolation function. During the adsorption stage, the polar groups in the polyetherimide outer shell layer preferentially undergo physical adsorption with SO2 molecules in the flue gas, forming a selective permeation barrier and preventing SO2 from diffusing into the core. The high-temperature conditions during the desorption stage cause the adsorbed SO2 to desorb from the outer shell layer, and the structure does not collapse due to the thermal stability of the coating layer. The potassium carbonate / alumina composite core maintains its activity through chemisorption during CO2 adsorption, while the outer shell protects the active sites from SO2 poisoning during cycling. By limiting the decay rate threshold after 10 cycles, the protective efficacy of the core-shell structure for the active components during long-term operation was verified. This invention, by constructing a coating layer with a molecular sieve effect, maintains CO2 diffusion channels while blocking SO2 permeation pathways, solving the performance degradation problem caused by chemical poisoning in traditional materials. Compared to simply increasing the specific surface area of ​​the carrier, this structural design achieves a synergistic improvement in adsorption selectivity and durability from a material interface engineering perspective. It effectively maintains the chemical stability of the adsorbent material in sulfur-containing flue gas environments, allowing the active components to maintain their original adsorption capacity during multiple adsorption-desorption cycles, significantly extending the service life of the adsorbent in industrial flue gas treatment systems, and reducing equipment maintenance frequency and operating costs.

[0043] The potassium-based low-temperature CO2 adsorbent with a core-shell structure synthesized in this invention has low production cost and exhibits good adsorption activity within the low-temperature adsorption range, showing promising potential for industrial applications. A polyetherimide (PEI) shell is modified onto the adsorbent powder to form a core-shell structure adsorbent. The PEI shell can specifically bind SO2, preventing the potassium-based adsorbent from being poisoned and deactivated by SO2 under actual flue gas conditions. After 10 cycles of adsorption-desorption experiments under simulated actual flue gas conditions, the adsorbent showed an adsorption capacity decrease of less than 10%, demonstrating excellent performance. The polyetherimide can also be replaced with tetraethylenepentamine.

[0044] The raw materials used in this invention include: analytical grade potassium carbonate and alumina, manufactured by Sinopharm; analytical grade tetraethylenepentamine, manufactured by McLean; and analytical grade PEI, manufactured by Sigma-Aldrich, with a melt flow rate of 9 g / 10 min.

[0045] A fixed-bed reactor was used for testing, with 8g of adsorbent material loaded for each test. The total flue gas flow rate was 300ml / min, simulating the flue gas composition after desulfurization and dust removal in a coal-fired unit: 12% CO2, 10% H2O(g), 78% N2, and 0.002% SO2. Adsorption was carried out at 50℃ with 8g of adsorbent material loaded. The flue gas flow rate was 100-300ml / min; the adsorption temperature was 50-70℃; and the desorption temperature was 140-160℃.

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0047] Example 1 First, weigh 8g of alumina powder and dissolve it in 18ml of water. After ultrasonic dispersion, add 8g of potassium carbonate powder and stir thoroughly in a stirring table for 2 hours. Then, transfer the mixture to a high-pressure reactor with a Teflon liner and heat it to 110℃ for 6 hours. After cooling to room temperature, filter and dry to obtain a white powder, which is designated as Sample 1.

[0048] 8g of sample 1 was loaded and subjected to adsorption reaction at 50℃ and desorption reaction at 120℃, for 10 cycles.

[0049] Figure 1 The figure shows the cyclic stability test of sample 1 prepared in Example 1 of the present invention; it can be seen from the figure that the performance of sample 1 decreased by 16.4% in 10 cycles of the test.

[0050] Example 2 In Example 1, 8g of potassium carbonate powder was replaced with 16g of potassium carbonate powder, while keeping other conditions unchanged. The resulting white powder was designated as Sample 2.

[0051] Example 3 In Example 1, 8g of potassium carbonate powder was replaced with 4g of potassium carbonate powder, while keeping the other conditions unchanged. The resulting white powder was designated as Sample 3.

[0052] Example 4 Dissolve 1g of PEI in 10ml of ethanol, add 10g of sample 1, ultrasonically disperse, transfer to a high-pressure reactor with a Teflon liner, heat to 80℃ and maintain for 6h, cool to room temperature, filter, and dry to obtain an adsorbent material with a core-shell structure, denoted as sample 4.

[0053] Example 5 In Example 4, 1g PEI was replaced with 3g PEI, while other conditions remained unchanged, and a white powder was obtained, which was recorded as Sample 5.

[0054] 8g of sample 5 was loaded, and the adsorption reaction was carried out at 50℃, followed by the desorption reaction at 120℃, for 10 cycles.

[0055] Figure 2 The figure shows the cyclic stability test of sample 5 prepared in Example 5 of the present invention; it can be seen from the figure that the performance of sample 5 decreased by 8.0% in 10 cycles of testing.

[0056] Example 6 In Example 5, PEI was replaced with tetraethylenepentamine, and the resulting sample was designated as Sample 6. Adsorption was carried out at 50°C, and desorption was carried out at 120°C for 10 cycles.

[0057] Example 7 In Example 5, the stirring and mixing time was set to 1.8 h, the hydrothermal reaction temperature was set to 120 °C, and the hydrothermal reaction time was set to 5.5 h; the solvothermal reaction temperature was set to 90 °C, and the solvothermal reaction time was set to 8 h.

[0058] Example 8 In Example 5, the stirring and mixing time was set to 1.5 h, the hydrothermal reaction temperature was set to 115 °C, and the hydrothermal reaction time was set to 5 h; the solvothermal reaction temperature was set to 85 °C, and the solvothermal reaction time was set to 7 h.

[0059] Figure 3 The figure shows the cyclic stability test of sample 6 prepared by Comparative Example 1 of this invention. As can be seen from the figure, the initial adsorption capacity of sample 6 is 135.2 mg / g, and the performance decreases by 13.0% in 10 cycles.

[0060] Table 1. Comparison of adsorption capacities of potassium-based low-temperature CO2 adsorbents with core-shell structures prepared in Examples 1-6

[0061] Table 1 compares the adsorption capacities of potassium-based low-temperature CO2 adsorbents with core-shell structures prepared in Examples 1-6. As can be seen from Examples 1-3, the adsorption capacity of the adsorbent gradually increases with the increase of potassium carbonate. This is because the increased content of potassium carbonate, as an active substance for CO2 adsorption, is beneficial to CO2 adsorption. However, the increase in potassium carbonate content and the increase in adsorption capacity are not linear, indicating that excessive potassium carbonate leads to the masking of some active sites. Examples 1, 4, and 5 show that the introduction of a PEI shell significantly improves the adsorption capacity of the material. Simultaneously, the introduction of PEI optimizes the cycling stability of the sample and alleviates the poisoning of the adsorbent by SO2. PEI plays a role in physical barrier and chemical passivation. By modifying the outer layer of conventional alumina / potassium carbonate powder with a polymer to form an adsorbent with a core-shell structure, under actual flue gas conditions, SO2 in the flue gas reacts with the polymer in the outer shell layer and does not diffuse to the alumina / potassium carbonate core. This ensures that the active component, potassium carbonate, is not poisoned by SO2, ultimately resulting in a highly active and durable adsorbent.

[0062] In summary, this invention relates to a potassium-based low-temperature CO2 adsorbent with a core-shell structure, its preparation method, and its application. Potassium carbonate is selected as the active ingredient, and alumina powder is used as the carrier to form the basic adsorbent material. A polyetherimide (PEI) shell is modified onto the surface of the basic adsorbent material to form a core-shell structured adsorbent. The performance of the adsorbent material is optimized by adjusting the ratio of potassium carbonate to alumina and the amount of PEI. Potassium carbonate, as the active ingredient, has the advantages of high adsorption capacity and low cost, and can effectively adsorb CO2. Alumina powder, as the carrier, provides a large specific surface area, which is beneficial to the dispersion and adsorption process of potassium carbonate. The PEI shell layer has the ability to specifically bind SO2, which can prevent SO2 from diffusing into the core, thereby protecting the active ingredient of potassium carbonate from SO2 poisoning. The core-shell structure design allows CO2 to reach the potassium carbonate core through the PEI shell, achieving efficient adsorption while avoiding SO2 poisoning of the active ingredient. By adjusting the ratio of potassium carbonate to alumina and the amount of PEI, the adsorption capacity and anti-poisoning performance can be optimized, achieving a balance between high activity and high durability.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a potassium-based low-temperature CO2 adsorbent material with a core-shell structure, characterized in that, include: 1) Dissolve alumina powder in water, disperse it ultrasonically, add potassium carbonate powder and stir to mix evenly. After hydrothermal reaction, filter and dry to obtain potassium carbonate / alumina composite powder. 2) After dissolving polyetherimide in ethanol, potassium carbonate / alumina composite powder is added and ultrasonically dispersed evenly. After solvothermal reaction, filtration and drying, potassium-based low-temperature CO2 adsorbent material with core-shell structure is obtained.

2. The method for preparing the potassium-based low-temperature CO2 adsorbent material with a core-shell structure according to claim 1, characterized in that, In step 1), the ratio of alumina powder, potassium carbonate powder and water is (4~16) g: 8 g: 18 mL.

3. The method for preparing the potassium-based low-temperature CO2 adsorbent material with a core-shell structure according to claim 1, characterized in that, In step 1), the stirring and mixing time is 1.5-2 hours; the hydrothermal reaction temperature is 110-120°C; and the hydrothermal reaction time is 5-6 hours.

4. The method for preparing the potassium-based low-temperature CO2 adsorbent material with a core-shell structure according to claim 1, characterized in that, In step 2), the ratio of polyetherimide, ethanol, and potassium carbonate / alumina composite powder is (1~3) g: 10 mL: 10 g.

5. The method for preparing a potassium-based low-temperature CO2 adsorbent material with a core-shell structure according to claim 1, characterized in that, In step 2), the temperature of the solvothermal reaction is 80-90℃; the time of the solvothermal reaction is 6-8h.

6. A potassium-based low-temperature CO2 adsorbent material with a core-shell structure, characterized in that, The potassium-based low-temperature CO2 adsorbent material with a core-shell structure as described in any one of claims 1 to 5 is prepared by the method described in claims 1 to 5. The core of the potassium-based low-temperature CO2 adsorbent material with a core-shell structure is an alumina support loaded with potassium carbonate, and the outer shell is a polyetherimide coating layer.

7. The potassium-based low-temperature CO2 adsorbent material with a core-shell structure according to claim 6, characterized in that, The polyetherimide coating layer accounts for 10%-30% of the total mass of the potassium-based low-temperature CO2 adsorbent material with a core-shell structure; the melt flow rate of the polyetherimide is 9-10 g / 10 min.

8. The application of the potassium-based low-temperature CO2 adsorbent material with a core-shell structure prepared by the method of any one of claims 1 to 5 in industrial flue gas treatment.

9. The application of the potassium-based low-temperature CO2 adsorbent material with a core-shell structure according to claim 8 in industrial flue gas treatment, characterized in that, A potassium-based low-temperature CO2 adsorbent with a core-shell structure was packed into a fixed-bed reactor, and simulated industrial flue gas was introduced to carry out the adsorption reaction; the flow rate of the simulated industrial flue gas was 100-300 mL / min; the adsorption temperature was 50-70℃, and the desorption temperature was 140-160℃.

10. The application of the potassium-based low-temperature CO2 adsorbent material with a core-shell structure according to claim 8 in industrial flue gas treatment, characterized in that, After 10 cycles of adsorption-desorption, the adsorption capacity decay rate is less than 10%.

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