A hierarchical porous CO2 adsorbent material and its preparation method

Abstract

The present invention discloses a hierarchically porous CO2 adsorption material and a preparation method thereof. The hierarchically porous CO2 adsorption material is prepared by photocuring 3D printing a photosensitive resin made of a photopolymerizable ionic liquid monomer, an amino-containing comonomer, a multi-functional crosslinking agent, a non-reactive pore-forming agent, etc., and then removing the pore-forming agent by supercritical drying. The present invention realizes the molecular-level uniform distribution of amino active sites, avoids the defects of traditional post-modification processes, and successfully constructs a multi-level pore structure conducive to gas mass transfer by combining polymerization-induced phase separation and supercritical drying. The prepared material has excellent CO2 adsorption performance and cycle stability, with an adsorption capacity of 4.5 mmol / g at 25 °C and 0.1 MPa, and a performance retention rate > 95% after 5 cycles.

Description

Technical Field

[0001] This invention belongs to the field of CO2 adsorption material preparation technology, specifically relating to a hierarchical porous CO2 adsorption material and its preparation method. Background Technology

[0002] The efficient capture and resource utilization of CO2 is key to achieving the goal of "carbon neutrality". As an abundant and renewable C1 resource, the targeted capture and recycling of CO2 is a crucial path to balance environmental protection and sustainable resource development, while the development of efficient CO2 adsorption materials is the core support for promoting the industrialization of this technology.

[0003] Polyionic liquids (PILs) combine the structural designability of ionic liquids with the mechanical stability of polymers. Ionic sites in their molecular structure can form specific interactions with CO2, exhibiting unique advantages in CO2 adsorption. However, traditional ionic liquid polymers typically lack high specific surface area and stable porous structures, resulting in low adsorption capacity and poor selectivity, limiting their applications in gas separation, catalysis, and other fields. Therefore, preparing porous structures for ionic liquid polymers to increase their specific surface area, promote mass transfer, and increase adsorption sites has become a current research hotspot. Current methods for preparing porous ionic liquid polymers mainly include hard template methods, soft template methods, electrostatic complexation methods, and crosslinking methods. However, these methods struggle to achieve precise control of macroscopic morphology and synergistic optimization of microscopic porous structures, limiting their application in large-scale CO2 capture.

[0004] Amine modification is an effective means to improve the adsorption performance of CO2 adsorbent materials. By introducing primary or secondary amines as active sites into the material, chemisorption reactions can occur to form carbamates, significantly improving adsorption capacity and selectivity. However, traditional amine modification strategies often employ a two-step approach: first preparing a polyionic liquid matrix, and then introducing amine active sites through subsequent surface modification. This method tends to result in uneven amine distribution, limited loading, weak binding to the substrate, and easy detachment during long-term use, affecting the adsorption stability and lifespan of the material. Another method is to modify ionic liquid monomers with amines, but the synthesis steps are cumbersome, requiring large amounts of solvent, which is not conducive to large-scale production.

[0005] 3D printing technology offers a novel approach to the precise control of the macroscopic morphology and microstructure of materials. Among them, photopolymerization printing, with its high forming accuracy and speed, can achieve customized fabrication of adsorption devices with complex structures. The introduction of porogens can further optimize the microporous structure of materials, increase specific surface area and expose active sites, and, combined with supercritical drying technology, effectively preserve the integrity of the porous structure. However, currently, no technology can achieve the synergistic unity of "integrated design at the amine molecular level - macroscopic forming by 3D printing - microporous construction - efficient CO2 adsorption," making it difficult to simultaneously consider the forming accuracy, porous structure, and adsorption performance of materials.

[0006] Therefore, developing a method to directly introduce amine-containing comonomers into ionic liquid formulations, combined with photopolymerization 3D printing and supercritical drying to remove pore-forming agents, to prepare polyionic liquid materials with precise macroscopic morphology, hierarchical porous structure and efficient amine-modified CO2 adsorption performance is of great significance for promoting the industrial application of CO2 capture technology and helping to achieve the goal of "carbon neutrality". Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention provides a hierarchical porous CO2 adsorbent material and its preparation method. This invention aims to address the problems of low adsorption capacity and poor selectivity in existing polyionic liquid materials, while improving upon the process defects of uneven distribution of active sites, cumbersome synthesis steps, and high solvent consumption during amine modification. This achieves synergistic optimization of the material's macroscopic shaping, microporous structure, and high-efficiency adsorption performance.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for preparing an amine-modified hierarchical porous CO2 adsorbent material includes the following steps:

[0010] 1) Preparation of homogeneous photosensitive resin

[0011] The photopolymerizable ionic liquid monomer, amine-containing comonomer, multifunctional crosslinking agent, non-reactive porogen, photoinitiator and photoabsorber are placed in a light-proof container and stirred in the dark at a temperature of 25~80°C and a speed of 500~3000 r / min for 5~120 min until the system is fully mixed at the molecular level to obtain a transparent and uniform photosensitive resin.

[0012] The photopolymerizable ionic liquid monomer is a 1-vinylimidazolium type monomer or an acrylate type monomer, with structural formulas as shown in formula (a) and formula (b), respectively, wherein R is an alkyl segment, X - It is one of the following: iodide ion, bromide ion, chloride ion, nitrate ion, trifluoromethanesulfonylimide, tetrafluoroborate ion, and hexafluorophosphate ion;

[0013]

[0014] 2) 3D model design and slicing

[0015] The macroscopic geometry of the target adsorber (such as honeycomb, grid, spiral or minimal three-period curved surface) is designed using 3D modeling software and imported into the slicing software of the 3D printing equipment to set the printing process parameters.

[0016] 3) Photopolymerization 3D printing molding and in-situ hole formation

[0017] The photosensitive resin prepared in step 1) is injected into the material tank of the 3D printing equipment and the printing program is started. During this process, as the photo-initiated polymerization reaction proceeds, polymerization-induced phase separation (PIPS) occurs in the system. As the degree of cross-linking of the polymer network increases, the non-reactive porogen that was originally dissolved in the monomer precipitates out due to the decrease in solubility, forming micro-phase separation. After printing is completed, a preform with a preset macroscopic configuration and rich in porogen is obtained.

[0018] 4) Supercritical drying to remove pore-forming agents (construction of hierarchical porous structures)

[0019] 4-1) Based on the miscibility between the porogen and the CO2 medium, perform either treatment A or treatment B to complete the liquid CO2 replacement:

[0020] Treatment A (direct displacement method): If the pore-forming agent (such as ethanol) is miscible with CO2, the above-mentioned printed preform is placed directly in a supercritical drying kettle, and liquid CO2 is introduced at -10~20°C and 1~10 MPa for solvent displacement for 3~10 h.

[0021] Treatment B (Indirect Replacement Method): If the pore-forming agent has poor miscibility with CO2 (such as water, highly polar solvents, etc.), first immerse the preform in a transitional solvent miscible with CO2 (such as ethanol, etc.) for 10 to 36 hours, changing the solvent 1 to 3 times during this period. After the pore-forming agent in the preform is completely replaced, transfer it to a supercritical drying reactor and pass liquid CO2 through it at -10 to 20°C and 1 to 10 MPa for solvent replacement for 3 to 10 hours.

[0022] 4-2) Supercritical drying treatment

[0023] After liquid CO2 replacement is completed, the temperature inside the reactor is raised to 31~80°C and the pressure is increased to 7.4~20MPa to bring CO2 to a supercritical state. After maintaining this state for 1~4 h, the pressure is slowly released to atmospheric pressure at a rate of 0.01~0.1MPa / min. By eliminating the gas-liquid interfacial tension, the collapse of the pore structure is prevented, and a hierarchical porous CO2 adsorption material with high specific surface area is finally obtained.

[0024] Further, the amine-containing comonomer, used to introduce functionalized amine sites, is selected from at least one of acrylamide-based, acrylate-based, or multifunctional amine-containing monomers. Preferably, the amine-containing comonomer is at least one of acrylamide, N-(hydroxymethyl)acrylamide, hydroxyethylacrylamide, N-isopropylacrylamide, tert-butylaminoethyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid, 1-methyl-3-(prop-2-enyl)urea, N-carbamoylacrylamide, and N-(isopropylcarbamoyl)acrylamide.

[0025] Further, the multifunctional crosslinking agent is selected from at least one of N,N'-methylenebisacrylamide, N,N'-methylenebismethylacrylamine, polyethylene glycol diacrylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, diethylene glycol diacrylate phthalate, tricyclodecanediethanol diacrylate, 1,4-butanediol diacrylate, 1,9-nonanediol diacrylate, 1,10-decanediol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate (including PEG200DA, PEG400DA, PEG600DA), polypropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, and polytetramethylene glycol diacrylate.

[0026] In particular, when the crosslinking agent is selected from amine-containing bifunctional or polyfunctional compounds (such as N,N'-methylenebisacrylamide, N,N'-methylenebismethylacrylamine), it can simultaneously provide a crosslinking structure and amine functional groups. In this case, the aforementioned amine-containing comonomers may not be added to the photosensitive resin, and the amine-containing crosslinking agent can solely assume the function of introducing amine groups.

[0027] Furthermore, the non-reactive porogen is selected from at least one of alcohols, ketones, esters, ethers, water, acetonitrile, and hexane; preferably at least one of ethanol, methanol, ethyl acetate, diethylene glycol dimethyl ether, and acetone.

[0028] Further, the photoinitiator is selected from at least one of the following: diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), liquid form of TPO-L, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone (Irgacure 2959), 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651), benzophenone (BP), camphorquinone (CQ), Irgacure 184, Irgacure 2100, lithium phenyl-2,4,6-trimethylbenzoyl phosphite (LAP), and a vitamin B2 (riboflavin) and triethanolamine (TEOA) complex.

[0029] Furthermore, the light absorber is selected from light-absorbing dyes, which are used to reduce the characteristic penetration depth of the resin, reduce internal light scattering, and strictly limit the curing reaction to the vicinity of the focal plane, thereby significantly improving the Z-axis resolution of 3D printing.

[0030] In step 1), the proportions of each raw material group by weight are as follows: 30-80 parts of photopolymerizable ionic liquid monomer, 0-50 parts of amine-containing comonomer, 3-30 parts of multifunctional crosslinking agent, 15-80 parts of non-reactive porogen, 0.5-10 parts of photoinitiator, and 0.01-15 parts of light absorber.

[0031] In step 2), the printing process parameters are as follows: single layer thickness: 10~200 μm; bottom layer exposure time: 15~40 s, normal layer exposure time: 3~20 s; exposure intensity: 3~10 mW / cm² 2 .

[0032] In step 2), the 3D printing equipment is selected from one of the following: stereolithography (SLA), digital light processing (DLP), liquid crystal display mask (LCD), continuous liquid interface manufacturing (CLIP), two-photon polymerization (TPP), and volumetric additive manufacturing (VAM) equipment.

[0033] This invention also provides a method for CO2 adsorption and material regeneration using the prepared hierarchical porous CO2 adsorption material, as detailed below:

[0034] 1. Initial degassing and activation treatment

[0035] Since CO2 is used as the medium during supercritical drying, some physically adsorbed CO2 may remain within the porous material. Procedure: Place the dried, graded porous CO2 adsorption material in a vacuum oven. Parameters: Treat at 90–250°C and a vacuum level below -0.01–-0.09 MPa for 0.5–8 hours. Purpose: To thoroughly remove residual gas from the pores and amine sites, releasing effective adsorption sites.

[0036] 2. Carbon dioxide adsorption process

[0037] The activated hierarchical porous CO2 adsorbent material is placed in a CO2-containing gas flow or sealed environment (such as simulated flue gas). Conditions: Adsorption is carried out at 0–80°C (preferably room temperature). The hierarchical porous structure of the material enables rapid gas diffusion, and the synergistic effect of the ionic liquid and amine sites achieves selective CO2 capture.

[0038] 3. Material Recycling and Reuse

[0039] Once the material reaches adsorption saturation, it needs to be regenerated. Procedure: Place the saturated sample back into a vacuum environment or under an inert atmosphere. Parameters: Heat treat at 80–250°C for 0.5–8 hours. Effect: Heat / vacuum-assisted desorption of chemically adsorbed CO2 restores the material's adsorption activity. The treated material can be repeatedly recycled and maintains a stable adsorption capacity.

[0040] This invention employs the above technical solution, wherein the amine-modified hierarchical porous CO2 adsorbent material is prepared by photopolymerization and 3D printing of a photosensitive resin containing amine monomers and porogens, followed by supercritical drying to remove the porogens. Compared with the prior art, this invention has the following beneficial effects:

[0041] 1. This invention achieves a uniform molecular-level distribution of amine active sites in the polyionic liquid network by directly introducing amine-containing comonomers or amine-containing crosslinking agents into the photosensitive resin. This avoids problems such as uneven site distribution, weak binding force, and easy detachment caused by traditional post-modification. At the same time, it eliminates the complicated amino monomer synthesis steps, making the process simple and environmentally friendly.

[0042] 2. This invention utilizes the polymerization-induced phase separation (PIPS) mechanism during photocuring to induce the non-reactive porogen to form uniformly dispersed micro / nano droplets in situ. Combined with supercritical drying technology to gently remove the porogen, a hierarchical porous structure possessing micropores, mesopores, and macropores was successfully constructed. This structure not only provides a high specific surface area and exposes more active sites, but also the macroporous channels promote gas mass transfer, significantly improving adsorption kinetics performance.

[0043] 3. The synergistic effect of the ionic liquid sites and amino active sites in this invention achieves a dual mechanism of physical and chemical adsorption. At 25°C and 0.1 MPa, the CO2 adsorption capacity reaches as high as 4.5 mmol / g, far exceeding that of traditional porous materials. After five adsorption-desorption cycles, the adsorption capacity retention rate remains above 95%, demonstrating excellent regeneration performance and long-term stability.

[0044] 4. This invention utilizes photopolymerization 3D printing technology to customize the macroscopic geometric structure (honeycomb, grid, minimal three-period curved surface, etc.) of the adsorbent according to actual application scenarios (such as flue gas channels, air contactors), realizing the integrated preparation of adsorption materials and devices, effectively reducing gas flow resistance, improving adsorption efficiency per unit volume, and providing feasibility for industrial applications.

[0045] 5. This invention designs two supercritical drying processes, direct displacement method and indirect displacement method, for porogens with different polarities, which expands the selection range of porogens and allows for flexible control of the pore size distribution and morphology of porous structures to meet the needs of different application scenarios. Attached Figure Description

[0046] Figure 1 This is a comparison graph of the carbon dioxide adsorption curves of the samples from Example 1 and Comparative Example 1.

[0047] Figure 2 This is an electron microscope image of the porous structure inside the sample of Example 1.

[0048] Figure 3 This is a comparison image of the green lattice structure printed by DLP 3D printing in Example 1 before and after drying.

[0049] Figure 4 This is an electron microscope image of the internal structure of the sample in Comparative Example 2. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0051] Example 1

[0052] A method for preparing an amine-modified hierarchical porous CO2 adsorbent material includes the following steps:

[0053] 1) Preparation of photosensitive resin

[0054] Weigh out 50 parts by weight of ionic liquid monomer (1-vinyl-3-butylimidazolium bromide), 15 parts by weight of amine-containing comonomer (acrylamide), 10 parts by weight of crosslinking agent (polyethylene glycol diacrylate), 20 parts by weight of non-reactive porogen (a 1:1 mixture of water and ethanol), 4 parts by weight of photoinitiator (BAPO), and 0.05 parts by weight of light absorber (olisen green pigment). Place the above components in a light-proof solder paste container and planetarily stir at 1000 r / min for 60 minutes at 40°C, avoiding light, until the system is completely transparent and homogeneous, thus obtaining a homogeneous photosensitive resin.

[0055] 2) 3D model design and slicing

[0056] A model of a minimal three-period surface (Gyroid) with an opening was designed using 3D modeling software. The model was exported as an STL file and imported into the slicing software for the DLP printer. Printing parameters were set as follows: single-layer thickness 50 μm, bottom layer exposure time 30 s, normal layer exposure time 8 s, and exposure intensity 5 mW / cm². 2 .

[0057] 3) Photopolymerization 3D printing molding and in-situ hole formation

[0058] The prepared photosensitive resin is poured into the resin tank of the DLP printer, with the liquid level slightly above the bottom. The printing program is started. Under ultraviolet light irradiation, the photoinitiator decomposes to generate free radicals, initiating copolymerization of the ionic liquid monomer (acrylamide) and the crosslinking agent. As polymerization proceeds, a polymer crosslinking network gradually forms. Ethanol and water, originally dissolved in the monomer, undergo polymerization-induced phase separation (PIPS) due to decreased solubility, forming nano- to micron-sized droplets dispersed in the polymer matrix. After printing, the preform is removed from the platform, and the unpolymerized resin on the surface is gently rinsed with ethanol to obtain a preform with a predetermined macroscopic shape and rich in pore-forming agent microdroplets.

[0059] 4) Supercritical drying

[0060] Since ethanol in the pore-forming agent has good miscibility with supercritical CO2, a direct displacement method (path A) is used for drying. The printed preform is placed in a supercritical drying vessel, the temperature is controlled at 5°C, the pressure is increased to 5 MPa, and liquid CO2 is continuously introduced at a flow rate of 0.5 L / min for 6 hours to gradually displace the ethanol in the preform. Subsequently, the temperature in the vessel is increased to 45°C and the pressure is increased to 10 MPa to bring the CO2 to a supercritical state. This state is maintained for 2 hours to allow the CO2 to fully dissolve the residual solvent and diffuse uniformly. Finally, the CO2 is slowly released to atmospheric pressure at a rate of 0.05 MPa / min to avoid damage to the pore structure due to rapid depressurization, resulting in a dry, non-shrinkage hierarchical porous polyionic liquid material (i.e., hierarchical porous CO2 adsorbent material).

[0061] The specific steps for CO2 adsorption and material regeneration using the above-mentioned hierarchical porous polyionic liquid material are as follows:

[0062] 1) Initial degassing and activation treatment

[0063] The dried hierarchical porous polyionic liquid material was placed in a vacuum oven and treated at 120°C and a vacuum of -0.08MPa for 4 hours to thoroughly remove the residual physically adsorbed CO2 and trace solvent in the pores and release the amine active sites.

[0064] 2) CO2 adsorption performance test

[0065] CO2 adsorption was tested on the hierarchical porous polyionic liquid material at 25°C using a gravimetric analyzer. Prior to the test, the hierarchical porous polyionic liquid material was degassed under high vacuum at 150°C for 3 hours. The results showed that the adsorption capacity of the sample reached 4.2 mmol / g at a CO2 pressure of 0.1 MPa.

[0066] The saturated samples were regenerated by treating them at 120°C under vacuum for 2 hours, followed by another adsorption test. After five cycles, the adsorption capacity remained above 4.1 mmol / g, with a capacity retention rate of >98%, indicating that the material has good regeneration stability.

[0067] Example 2

[0068] A method for preparing an amine-modified hierarchical porous CO2 adsorbent material includes the following steps:

[0069] 1) Preparation of photosensitive resin

[0070] Weigh out 60 parts by weight of ionic liquid monomer (1-vinyl-3-methylimidazolium tetrafluoroborate), 18 parts by weight of amino-containing bifunctional crosslinking agent (N,N'-methylenebismethylpropyleneamine), 50 parts by weight of non-reactive porogen (ethyl acetate), 4 parts by weight of photoinitiator (BAPO), and 0.05 parts by weight of light absorber (Olive Orange Powder). Place the above components in a light-proof solder paste container and planetarily stir at 2000 r / min for 20 minutes at 25°C, avoiding light, until the system is completely transparent and homogeneous, thus obtaining a homogeneous photosensitive resin.

[0071] 2) 3D model design and slicing

[0072] Design a grid-like structure model with a cube shape of 30×30×5 mm. Import the model into the slicing software of an SLA printer and set the printing parameters as follows: single-layer thickness of 100 μm, laser scanning speed of 2 m / s, and laser power of 100 mW.

[0073] 3) Photopolymerization 3D printing molding

[0074] Resin is injected into the resin tank of the SLA printer, and printing is started. Under laser scanning, polymerization and cross-linking are initiated, and PIPS (Polyethylene Bismuth Injection) occurs simultaneously, with ethyl acetate microphases separating to form droplets. After printing, the preform is removed, and residual resin on the surface is cleaned with isopropanol to obtain a grid-like preform.

[0075] 4) Supercritical drying

[0076] Due to the good miscibility of ethyl acetate and CO2, a direct displacement method was used for drying. The preform was placed in a supercritical drying vessel, and liquid CO2 was continuously introduced at 0°C and 6 MPa for 8 hours for displacement. Subsequently, the temperature inside the vessel was increased to 40°C and the pressure to 12 MPa, allowing the CO2 to reach a supercritical state and maintaining this state for 3 hours to fully dissolve and displace the residual ethyl acetate. Finally, CO2 was slowly released to atmospheric pressure at a rate of 0.03 MPa / min to avoid damage to the pore structure due to rapid pressure release, resulting in a dry, structurally intact hierarchical porous CO2 adsorbent material.

[0077] The specific steps for CO2 adsorption and material regeneration using the above-mentioned hierarchical porous polyionic liquid material are as follows:

[0078] CO2 adsorption tests were performed on the samples using a gravimetric analyzer at 25°C. Prior to the test, the samples were activated at 150°C under a vacuum of -0.09 MPa for 3 hours. The results showed that the adsorption capacity of the samples reached 3.8 mmol / g at a CO2 pressure of 0.1 MPa. The saturated samples were regenerated by treating them at 120°C under vacuum for 2 hours, followed by another adsorption test. After five cycles, the adsorption capacity remained above 3.7 mmol / g, with a capacity retention rate >97%, indicating good regeneration stability of the material.

[0079] Example 3

[0080] A method for preparing an amine-modified hierarchical porous CO2 adsorbent material includes the following steps:

[0081] 1) Preparation of photosensitive resin

[0082] Weigh out 40 parts by weight of ionic liquid monomer (1-vinyl-3-ethylimidazolium tetrafluoroborate), 30 parts by weight of amine-containing comonomer (2-acrylamido-2-methylpropanesulfonic acid), 25 parts by weight of trifunctional crosslinking agent (trimethylolpropane triacrylate), 60 parts by weight of non-reactive porogen (diethylene glycol dimethyl ether), and 5 parts by weight of photoinitiator (TPO). Place the above components in a light-proof solder paste container and stir at 1000 r / min at 60 °C in the dark for 30 minutes until the system is completely transparent and homogeneous, thus obtaining a homogeneous photosensitive resin.

[0083] 2) Model Design and Printing

[0084] Design a 3D model of a crystal lattice structure. Import the model into the slicing software of an LCD printer and set the printing parameters as follows: single-layer thickness of 25 μm, bottom layer exposure time of 40 s, normal layer exposure time of 5 s, and light source intensity of 8 mW / cm². 2 .

[0085] 3) Photopolymerization 3D printing involves injecting photosensitive resin into the feed tank of an LCD printer and starting the printing program. During this process, as the photo-initiated polymerization reaction proceeds, polymerization-induced phase separation occurs in the system. As the degree of cross-linking of the polymer network increases, the non-reactive porogens originally dissolved in the monomers precipitate out due to decreased solubility, resulting in microscopic phase separation. After printing, a preform with a preset macroscopic configuration and rich in porogen microdroplets is obtained.

[0086] 4) Supercritical drying

[0087] Due to the good miscibility between diethylene glycol dimethyl ether and CO2, a direct displacement method was used for drying. The printed preform was placed in a supercritical drying vessel, and liquid CO2 was continuously introduced at 10°C and 8 MPa for 5 hours for displacement. Subsequently, the temperature inside the vessel was raised to 50°C and the pressure was raised to 15 MPa to bring the CO2 to a supercritical state and maintain it for 2.5 hours to fully dissolve and displace the residual diethylene glycol dimethyl ether. Finally, CO2 was slowly released to atmospheric pressure at a rate of 0.04 MPa / min to obtain a dry, structurally intact hierarchical porous CO2 adsorbent material.

[0088] The specific steps for CO2 adsorption and material regeneration using the above-mentioned hierarchical porous polyionic liquid material are as follows:

[0089] CO2 adsorption tests were performed on the samples using a gravimetric analyzer at 25°C. Before testing, the samples were activated at 200°C under a vacuum of -0.01 MPa for 2 hours. At a CO2 pressure of 0.1 MPa, the adsorption capacity of the sample reached 4.5 mmol / g. The saturated samples were regenerated by treating them at 200°C under vacuum for 2 hours, followed by another adsorption test. After five cycles, the adsorption capacity remained above 4.4 mmol / g, with a capacity retention rate >95.5%, indicating good regeneration stability of the material.

[0090] Example 4

[0091] A method for preparing an amine-modified hierarchical porous CO2 adsorbent material includes the following steps:

[0092] 1) Preparation of photosensitive resin

[0093] Weigh out the following components by weight: 70 parts of ionic liquid monomer (1-vinyl-3-ethylimidazolium hexafluorophosphate), 15 parts of amine-containing comonomer (N-isopropylacrylamide), 12 parts of crosslinking agent (polyethylene glycol diacrylate), 30 parts of pore-forming agent (deionized water), 2 parts of photoinitiator phenyl-2,4,6-trimethylbenzoyl lithium phosphite (LAP), and 0.2 parts of light absorber (tartrazine). Place the above components in a light-proof solder paste container and planetarily stir at 1500 r / min for 20 minutes at 25°C, avoiding light, until the system is completely transparent and homogeneous, thus obtaining a homogeneous photosensitive resin.

[0094] 2) Model Design and Printing

[0095] Design a 3D model of a Gyroid minimal three-period surface structure. Import the model into the slicing software of an LCD printer and set the printing parameters as follows: single layer thickness 20 μm, bottom layer exposure time 10 s, normal layer exposure time 3 s, and light source intensity 15 mW / cm².

[0096] 3) Photopolymerization 3D printing involves injecting photosensitive resin into the feed tank of an LCD printer and starting the printing program. During this process, as the photo-initiated polymerization reaction proceeds, polymerization-induced phase separation occurs in the system. As the degree of cross-linking of the polymer network increases, the non-reactive porogens originally dissolved in the monomers precipitate out due to decreased solubility, resulting in microscopic phase separation. After printing, a preform with a preset macroscopic configuration and rich in porogen microdroplets is obtained.

[0097] 4) Supercritical drying

[0098] Since deionized water is not directly miscible with supercritical CO2, solvent replacement is required first: the printed embryo is immersed in anhydrous ethanol and soaked at room temperature for 24 hours, during which fresh ethanol is replaced three times (once every 8 hours). The weight is monitored until the mass of the embryo no longer changes, indicating that the internal water has been completely replaced by ethanol. Then, supercritical drying is carried out using the direct replacement method: the replaced sample is placed in a supercritical drying vessel, and liquid CO2 is continuously introduced at 5°C and 4 MPa for 5 hours to gradually replace the ethanol in the embryo; then the temperature inside the vessel is raised to 45°C and the pressure is raised to 12 MPa to bring the CO2 to a supercritical state and maintain it for 2 hours; finally, CO2 is slowly released to atmospheric pressure at a rate of 0.05 MPa / min to obtain a dry, structurally intact hierarchical porous CO2 adsorbent material.

[0099] The specific steps for CO2 adsorption and material regeneration using the above-mentioned hierarchical porous polyionic liquid material are as follows:

[0100] CO2 adsorption of the samples was tested using a gravimetric analyzer at 25 °C. Prior to the test, the samples were activated at 100 °C under a vacuum of -0.05 MPa for 6 hours. The results showed that the adsorption capacity of the samples reached 3.9 mmol / g at a CO2 pressure of 0.1 MPa. The saturated samples were regenerated by treating them at 100 °C under vacuum for 2 hours, followed by another adsorption test. After five cycles, the adsorption capacity remained above 3.8 mmol / g, with a capacity retention rate >97.4%, indicating good regeneration stability of the material.

[0101] Comparative Example 1

[0102] In Example 1, 15 parts of the amine-containing comonomer acrylamide were replaced with an equal amount of amine-free isobornyl acrylate. All other preparation, printing, drying, and activation adsorption testing methods remained consistent with Example 1. The test results showed that at 25°C and 0.1 MPa CO2 pressure, the adsorption capacity of the sample was only 1.1 mmol / g, significantly lower than the 4.2 mmol / g in Example 1. This indicates that amine functional groups are crucial for achieving efficient CO2 chemisorption, and the lack of amine sites leads to a substantial decrease in adsorption capacity.

[0103] Comparative Example 2

[0104] The preparation, printing, and activation adsorption testing methods for this comparative example were consistent with those in Example 1. However, the pore-forming agent was removed using a conventional evaporation method. The printed preform was directly placed in a 60 °C ordinary oven and left at atmospheric pressure for 24 hours to allow the ethanol to evaporate naturally. During the evaporation process, a large capillary tension was generated at the gas-liquid interface, leading to the closure of the porous structure. Internal observation showed that most pores were closed. CO2 adsorption testing showed an adsorption capacity of only 0.8 mmol / g at 25 °C and 1 bar.

Claims

1. A method for preparing a hierarchical porous CO2 adsorption material, characterized in that, Includes the following steps: 1) Preparation of photosensitive resin Photopolymerizable ionic liquid monomer, amine-containing comonomer, multifunctional crosslinking agent, non-reactive porogen, photoinitiator and light absorber are placed in a light-proof container and stirred in the dark at 25~80°C for 5~120 min to obtain photosensitive resin. The photopolymerizable ionic liquid monomer is a 1-vinylimidazolium type monomer or an acrylate type monomer, with the structural formulas shown in formulas (a) and (b), respectively, where R is an alkyl segment and X... - It is one of the following: iodide ion, bromide ion, chloride ion, nitrate ion, trifluoromethanesulfonylimide, tetrafluoroborate ion, and hexafluorophosphate ion; ； 2) 3D model design and slicing The macroscopic geometry of the target adsorber was designed using 3D modeling software and then imported into the slicing software of the 3D printing equipment to set the printing process parameters. 3) Photopolymerization 3D printing molding and in-situ hole formation The photosensitive resin prepared in step 1) is injected into the material tank of the 3D printing equipment, the printing program is started, and after printing is completed, a preform with a preset macroscopic structure and rich in pore-forming agent is obtained. 4) Supercritical drying to remove pore-forming agents 4-1) Based on the miscibility between the pore-forming agent and the CO2 medium, perform either treatment A or treatment B as follows to complete the liquid CO2 replacement: Treatment A: If the pore-forming agent and CO2 are miscible, place the above-mentioned printed preform directly in a supercritical drying kettle, and pass liquid CO2 through it for solvent replacement at -10~20°C and 1~10 MPa for 3~10 h. Treatment B: If the pore-forming agent has poor miscibility with CO2, first immerse the preform in a transitional solvent miscible with CO2 for 10-36 hours, changing the solvent 1-3 times during this period. After the pore-forming agent in the preform is completely replaced, transfer it to a supercritical drying reactor and pass liquid CO2 through it at -10-20°C and 1-10 MPa for solvent replacement for 3-10 hours. 4-2) Supercritical drying treatment After liquid CO2 replacement is completed, the temperature inside the reactor is raised to 31~80°C and the pressure is increased to 7.4~20MPa to bring CO2 to a supercritical state. This state is maintained for 1~4 hours, and then the pressure is released to atmospheric pressure to obtain a hierarchical porous CO2 adsorption material.

2. The method for preparing a hierarchical porous CO2 adsorption material according to claim 1, characterized in that, The amine-containing comonomer is at least one of acrylamide, N-(hydroxymethyl)acrylamide, hydroxyethylacrylamide, N-isopropylacrylamide, tert-butylaminoethyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid, 1-methyl-3-(prop-2-enyl)urea, N-carbamoylacrylamide, and N-(isopropylcarbamoyl)acrylamide.

3. The method for preparing a hierarchical porous CO2 adsorption material according to claim 1, characterized in that, The multifunctional crosslinking agent is selected from at least one of N,N'-methylenebisacrylamide, N,N'-methylenebismethylacrylamine, polyethylene glycol diacrylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, ethylene glycol dimethacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, diethylene glycol diacrylate phthalate, tricyclodecanediethanol diacrylate, 1,4-butanediol diacrylate, 1,9-nonanediol diacrylate, 1,10-decanediol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, and polytetramethylene glycol diacrylate.

4. The method for preparing a hierarchical porous CO2 adsorption material according to claim 1, characterized in that, The non-reactive porogen is selected from at least one of alcohols, ketones, esters, ethers, water, acetonitrile, and hexane.

5. The method for preparing a hierarchical porous CO2 adsorption material according to claim 1, characterized in that, The photoinitiator is selected from at least one of the following: diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, liquid form of TPO-L, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, 2,2-dimethoxy-2-phenylacetophenone, benzophenone, camphorquinone, Irgacure 184, Irgacure 2100, lithium phenyl-2,4,6-trimethylbenzoyl phosphite, and a complex of vitamin B2 and triethanolamine.

6. The method for preparing a hierarchical porous CO2 adsorption material according to claim 1, characterized in that, The light absorber is a light-absorbing dye.

7. The method for preparing a hierarchical porous CO2 adsorption material according to claim 1, characterized in that, In step 1), the proportions of each raw material group by weight are as follows: 30-80 parts of photopolymerizable ionic liquid monomer, 0-50 parts of amine-containing comonomer, 3-30 parts of multifunctional crosslinking agent, 15-80 parts of non-reactive porogen, 0.5-10 parts of photoinitiator, and 0.01-15 parts of light absorber.

8. The method for preparing a hierarchical porous CO2 adsorption material according to claim 1, characterized in that, In step 2), the printing process parameters are: single layer thickness: 10~200 μm; bottom layer exposure time: 15~40 s, normal layer exposure time: 3~20 s; Exposure intensity: 3~10 mW / cm 2 .

9. The method for preparing a hierarchical porous CO2 adsorption material according to claim 1, characterized in that, In step 2), the 3D printing equipment is selected from one of the following: stereolithography, digital light processing, liquid crystal display mask, continuous liquid interface manufacturing, two-photon polymerization, and volumetric additive manufacturing equipment.

10. The hierarchical porous CO2 adsorbent material obtained by the preparation method according to any one of claims 1 to 9.

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