An ethanolamine-modified KMnF3@Zn-MOF-74 hybrid matrix membrane and its preparation method

Abstract

This invention discloses an ethanolamine-modified KMnF3@Zn-MOF-74 hybrid matrix membrane and its preparation method, belonging to the field of gas separation membrane technology. The method uses KMnF3 nanoparticles as the core, and Zn-MOF-74 is grown in situ on their surface to obtain a core-shell structured KMnF3@Zn-MOF-74. Subsequently, ethanolamine is used to modify it by amination, allowing the -OH and -NH2 groups in the ethanolamine to coordinate or hydrogen bond with the open metal sites of Zn-MOF-74, thereby significantly improving the polarity of the filler and its interfacial compatibility with Pebax-1657. The modified KMnF3@Zn-MOF-74 is uniformly dispersed in a Pebax-1657 polymer matrix to prepare an ethanolamine-modified KMnF3@Zn-MOF-74 Pebax-1657 hybrid matrix membrane, which significantly improves the selectivity and permeability of the CO2 / N2 system. The preparation process of this invention is mild and simple, highly controllable, and the resulting membrane has a stable structure and excellent performance, which can be widely used in the field of CO2 capture and separation.

Description

Technical Field

[0001] This invention belongs to the field of gas separation membrane technology, specifically relating to an ethanolamine-modified KMnF3@Zn-MOF-74 mixed matrix membrane and its preparation method, which belongs to the preparation and performance optimization technology of functionalized separation membrane materials. Background Technology

[0002] Traditional polymer membranes such as polyimide, polysulfone, and Pebax are widely used in CO2 separation, but they suffer from a "trade-off effect" where permeability and selectivity are difficult to balance. Pebax series membranes are composed of polyamide (PA) and polyether (PE), where PA provides mechanical strength and the PE segment provides flexibility and polar adsorption capacity. Pebax-1657, in particular, stands out in CO2 separation membranes due to its moderate PA:PE ratio and balance between mechanical properties and polar adsorption. To overcome the limitations of single polymer performance, researchers have proposed the concept of "mixed matrix membranes (MMM)," which introduces inorganic porous materials with high selectivity and high adsorption capacity into organic polymers to achieve a synergistic effect. In recent years, metal-organic frameworks (MOFs) have become ideal fillers due to their highly tunable pore size, chemical modifiability, and high specific surface area.

[0003] KMnF3 is a typical perovskite fluoride material with a stable ABX3 structural framework, in which K + Occupying position A, Mn 2+ Occupy position B, F - As a framework coordination anion, the perovskite crystal surface, thanks to its rigid lattice, strong ionic bond structure, and thermal stability, can provide a large amount of Mn. 2+ Related coordination sites, therefore in Zn 2+ In the presence of organic ligands (such as 2,5-dihydroxyterephthalic acid), Zn-MOF-74 can be effectively induced to grow epitaxially on its surface, forming a uniform and dense KMnF3@Zn-MOF-74 core-shell structure. This structure not only improves the mechanical strength and dispersibility of Zn-MOF-74 particles but also enhances the overall robustness and structural integrity of the composite material. Based on these properties, KMnF3, as the core material of MOF core-shell structures, has broad application potential in gas separation, adsorption, catalysis, and composite membrane preparation.

[0004] Zn-MOF-74 (also known as CPO-27-Zn) is a typical one-dimensional porous MOF with open metal sites, which can coordinate with oxygen atoms in CO2 molecules or undergo van der Waals interactions, thus exhibiting excellent CO2 adsorption capacity. However, it has poor dispersibility in polymers, a hydrophobic surface, and limited compatibility with Pebax interfaces, making it prone to non-selective defects.

[0005] Ethanolamine (HO-CH2-CH2-NH2) is a polar molecule containing both -OH and -NH2 bifunctional groups, meaning it can react with Zn. 2+ Ionic coordination can also interact with the polyether segment through hydrogen bonds, thereby forming a stable interfacial layer between the inorganic filler and the polymer. Its molecular structure possesses both hydrogen bond donor and acceptor properties, which can significantly enhance the surface polarity and CO2 adsorption activity of MOF.

[0006] Therefore, introducing ethanolamine-modified KMnF3@Zn-MOF-74 into Pebax-1657 can not only improve the dispersibility of the filler, but also enhance interfacial coupling, construct continuous CO2 transport channels, and achieve a synergistic improvement in membrane permeability and selectivity. Summary of the Invention

[0007] The present invention aims to propose an ethanolamine-modified KMnF3@Zn-MOF-74 mixed matrix membrane and its preparation method, which improves its dispersibility and interfacial bonding ability in Pebax matrix, thereby significantly improving CO2 separation performance and solving the problems of low permeability and selectivity of membrane materials for CO2 / N2.

[0008] To address the aforementioned technical problems, this invention provides an ethanolamine-modified KMnF3@Zn-MOF-74 mixed matrix membrane and its preparation method, as follows:

[0009] The synthesized KMnF3 particles were dispersed in a solution containing Zn. 2+ In the precursor solvent system, Zn is uniformly dispersed in the solution under ultrasonic and stirring conditions. 2+Heterogeneous nucleation preferentially occurs on the surface of KMnF3; subsequently, an organic ligand 2,5-dihydroxyterephthalic acid (H4DOBDC) is added to the solvent system and the reaction is carried out in a closed reactor. During the reaction, the nucleated KMnF3 undergoes a coordination reaction with the H4DOBDC ligand, and Zn-MOF-74 crystals gradually grow along the surface of KMnF3 and interconnect with each other, forming a continuous MOF shell coating the outer layer of KMnF3; with the extension of reaction time, the Zn-MOF-74 shell gradually thickens and tends to be complete, finally yielding a KMnF3@Zn-MOF-74 core-shell composite material. The synthesized KMnF3@Zn-MOF-74 core-shell structured material was dispersed in an ethanolamine solution for modification, allowing ethanolamine molecules to fully contact and act on the Zn-MOF-74 shell. Subsequently, the modified material was washed with an ethanol-water mixture to remove physically adsorbed or weakly bound ethanolamine molecules, ensuring that ethanolamine could stably bind to the open metal sites in Zn-MOF-74 through coordination or hydrogen bonding, resulting in an ethanolamine-modified KMnF3@Zn-MOF-74 composite filler. The ethanol solution of the modified KMnF3@Zn-MOF-74 material was mixed with a Pebax-1657 solution to prepare the casting solution required for casting. A mixed matrix membrane was prepared using a solvent evaporation method, ultimately yielding the ethanolamine-modified KMnF3@Zn-MOF-74 mixed matrix membrane.

[0010] Based on the above technical solution, an ethanolamine-modified KMnF3@Zn-MOF-74 hybrid matrix membrane and its preparation method are disclosed, comprising the following steps:

[0011] Step 1: Preparation of KMnF3@Zn-MOF-74 core-shell structured filler: Zinc nitrate hexahydrate was dissolved in a first mixed solvent of N,N-dimethylformamide and water, KMnF3 nanoparticles were added and stirred to obtain mixture A; 2,5-dihydroxyterephthalic acid was dissolved in a second mixed solvent of N,N-dimethylformamide and water to obtain ligand solution B; ligand solution B was added to mixture A, stirred evenly, and then transferred to a reaction vessel for reaction. After the reaction was completed, the mixture was washed and dried to obtain KMnF3@Zn-MOF-74 core-shell structured filler.

[0012] Step 2: Preparation of ethanolamine-modified filler: The KMnF3@Zn-MOF-74 core-shell structure filler obtained in Step 1 was dispersed in anhydrous ethanol, ethanolamine was added, and the mixture was magnetically stirred at room temperature for 20-24 hours. After centrifugation, the filler was washed 2-3 times with anhydrous ethanol and vacuum dried for 18-24 hours to obtain the ethanolamine-modified KMnF3@Zn-MOF-74 core-shell structure filler.

[0013] Step 3: Preparation of polymer casting solution: Pebax-1657 is uniformly dispersed in a mixed solvent of ethanol and water, heated and stirred until completely dissolved to obtain Pebax casting solution;

[0014] Step 4: Preparation of the mixed matrix membrane: The ethanolamine-modified KMnF3@Zn-MOF-74 core-shell structure filler obtained in Step 2 is added to the Pebax casting solution obtained in Step 3, dispersed evenly, and stirred at room temperature for 1-1.5 hours. The resulting casting solution is cast onto a clean polytetrafluoroethylene plate and placed in a constant temperature oven at 60-85℃ for 18-24 hours. Then, it is placed in a vacuum oven and dried at 60-85℃ for another 18-24 hours to obtain the ethanolamine-modified KMnF3@Zn-MOF-74 mixed matrix gas separation membrane.

[0015] Further, the preparation method of the KMnF3 nanoparticles is as follows: manganese chloride tetrahydrate, hexadecyltrimethylammonium bromide, 1-butanol, octane and deionized water are magnetically stirred at room temperature for 20-30 min to form a first microemulsion; potassium fluoride dihydrate, hexadecyltrimethylammonium bromide, 1-butanol, octane and deionized water are weighed and magnetically stirred at room temperature for 20-30 min to obtain a second microemulsion; the second microemulsion is slowly added dropwise to the first microemulsion to obtain a mixed solution; the mixture is reacted for 5 min and then an excess of CHCl3 / CH3OH mixed solution is added to terminate the reaction; the mixture is washed and centrifuged multiple times with methanol and deionized water, and dried at 60-80℃ for 12-24 hours to obtain KMnF3 nanoparticles;

[0016] Further, in step 1, the mass ratio of 2,5-dihydroxyterephthalic acid: zinc nitrate hexahydrate: KMnF3 nanoparticles: N,N-dimethylformamide: water is 1:2.5~3:1:90~120:20;

[0017] Further, in step 2, the amount of ethanolamine added is 0.1~1.0 wt.% of the total mass of the anhydrous ethanol and ethanolamine.

[0018] Furthermore, in step 3, the mass concentration of Pebax-1657 in the Pebax casting solution is 1%~5%;

[0019] Furthermore, in step 3, the mass ratio of ethanol to water in the mixed solvent of ethanol and water is 6~9:4~1;

[0020] Further, in step 4, the amount of the ethanolamine-modified KMnF3@Zn-MOF-74 filler added, based on its mass percentage of the Pebax-1657 polymer, is 3 wt.% to 9 wt.%.

[0021] Furthermore, in preparing the KMnF3 nanoparticles, the mass ratio of manganese chloride tetrahydrate: potassium fluoride dihydrate: hexadecyltrimethylammonium bromide: 1-butanol: octane: deionized water is 1:1.3~1.5:13~16:9~13:40~60:5~10;

[0022] Furthermore, an ethanolamine-modified KMnF3@Zn-MOF-74 mixed matrix membrane and its preparation method are disclosed, which are prepared by the above-described method.

[0023] Furthermore, an ethanolamine-modified KMnF3@Zn-MOF-74 mixed matrix membrane and its preparation method are characterized by solving the problems of low CO2 / N2 permeability and selectivity of the membrane material. Its CO2 (PCO2) permeability can reach 78~97 Barrer, and its CO2 / N2 selectivity is 80~87.

[0024] Based on the above technical solutions, the structural formulas of the aforementioned substances are as follows:

[0025] The structural formula of KMnF3 is:

[0026]

[0027] The structural formula of Zn-MOF-74 is:

[0028]

[0029] The structural formula of ethanolamine is:

[0030]

[0031] The structural formula for Pebax-1657 is:

[0032]

[0033] This invention constructs a KMnF3@Zn-MOF-74 core-shell composite filler by in-situ growth of Zn-MOF-74 on the surface of KMnF3 particles. The Zn-MOF-74 material is composed of metallic Zn 2+ With 2,5-dihydroxyterephthalic acid ligand (DOBDC) 2-The Zn-MOF-74 composite material forms a one-dimensional open pore structure with regular pore size and strong orientation. The framework contains numerous open metal sites that can electrostatically attract and coordinate with oxygen atoms in CO2 molecules, providing efficient channels for the selective adsorption and transport of CO2. However, when Zn-MOF-74 is used alone, its particles are prone to agglomeration, and its relatively hydrophobic surface results in poor interfacial compatibility with the Pebax-1657 polymer matrix. This easily leads to the formation of non-selective interfacial defect channels in the mixed matrix film, thus limiting further improvement in its separation performance. KMnF3, as a structurally stable inorganic core, not only provides abundant surface active sites for the heterogeneous nucleation and directional growth of Zn-MOF-74 but also effectively inhibits the disordered agglomeration of MOF crystals. This allows Zn-MOF-74 to uniformly coat the KMnF3 surface in a continuous and dense shell form, significantly improving the structural integrity and dispersion stability of the composite filler. This core-shell structure maintains the one-dimensional open-pore structure and high specific surface area of ​​Zn-MOF-74 while enhancing its overall mechanical stability and processability in polymer matrices.

[0034] Furthermore, this invention introduces ethanolamine to modify the KMnF3@Zn-MOF-74 core-shell structure. Ethanolamine molecules contain both -NH2 and -OH bifunctional groups. The amino group can coordinate with open metal sites in the Zn-MOF-74 shell, while the hydroxyl group can form a stable interfacial bonding network with the C–O–C groups in the Pebax-1657 polyether segment through hydrogen bonding. After ethanolamine modification, the surface polarity of the Zn-MOF-74 shell is significantly enhanced, which not only improves the interfacial compatibility between the core-shell filler and the Pebax matrix, reducing the formation of interfacial voids and non-selective defects, but also provides additional chemisorption sites for CO2 molecules through the introduced amino and hydroxyl functional groups, thereby enhancing the solubility and migration of CO2 in the membrane.

[0035] The ethanolamine modification process largely preserves the original one-dimensional pore structure and crystal framework of Zn-MOF-74, allowing it to maintain high porosity and pore orientation while also possessing higher surface polarity and interfacial stability. When the ethanolamine-modified KMnF3@Zn-MOF-74 core-shell composite filler is blended into the Pebax-1657 matrix, it can construct numerous continuous transport channels with selective CO2 adsorption capacity within the membrane, achieving a synergistic enhancement of the dissolution-diffusion mechanism and the molecular sieving effect. Simultaneously, the introduction of the KMnF3 core helps stabilize the spatial distribution of the MOF shell within the membrane, further suppressing the formation of non-selective gas channels.

[0036] In summary, this invention, through a synergistic strategy of "KMnF3 core-shell structure regulation + ethanolamine surface functionalization + Pebax-1657 co-blending film formation", significantly improves the dispersibility and interfacial stability of the filler while enhancing the selective adsorption and directional transport capabilities of the membrane material for CO2, thereby significantly improving the permeation rate and separation selectivity of the CO2 / N2 system. Attached Figure Description

[0037] Figure 1 X-ray diffraction patterns of the sample prepared in Example 1 and the sample prepared in Comparative Example 6;

[0038] Figure 2 The images show the FT-IR spectra of the samples prepared in Examples 1-4 and Comparative Example 1. Detailed Implementation

[0039] The following examples illustrate the technical solutions of the present invention, but the scope of protection of the present invention is not limited to the examples listed:

[0040] All materials used in the following examples were commercially available. Pebax-1657 was purchased from Arkema, France; N,N-dimethylformamide solution was purchased from Tianjin Damao Chemical Reagent Co., Ltd.; ethanol was purchased from Shanghai McLean Biochemical Technology Co., Ltd.; methanol was purchased from Shanghai McLean Biochemical Technology Co., Ltd.; ethanolamine was purchased from Shanghai McLean Biochemical Technology Co., Ltd.; 2,5-dihydroxyterephthalic acid was purchased from Aladdin Chemical Reagent Co., Ltd.; manganese chloride tetrahydrate was purchased from Aladdin Chemical Reagent Co., Ltd.; potassium fluoride dihydrate was purchased from Aladdin Chemical Reagent Co., Ltd.; hexadecyltrimethylammonium bromide was purchased from Aladdin Chemical Reagent Co., Ltd.; octane was purchased from Aladdin Chemical Reagent Co., Ltd.; and n-butanol was purchased from Shanghai McLean Biochemical Technology Co., Ltd.

[0041] The following examples illustrate a method for improving the CO2 separation performance of an ethanolamine-modified KMnF3@Zn-MOF-74 hybrid matrix membrane (Pebax-1657) provided by the present invention.

[0042] Example 1:

[0043] Preparation of KMnF3: 0.416 g manganese chloride tetrahydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were magnetically stirred at room temperature for 20-30 min to form a first microemulsion. 0.592 g potassium fluoride dihydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were weighed and magnetically stirred at room temperature for 20-30 min to obtain a second microemulsion. The second microemulsion was slowly added dropwise to the first microemulsion to prepare a mixture. The mixture was reacted for 5 min, and then an excess of CHCl3 / CH3OH mixed solution was added to terminate the reaction. The mixture was washed repeatedly with methanol and deionized water, centrifuged, and dried at 60-80 °C for 12-24 hours to obtain KMnF3 nanoparticles.

[0044] Preparation method of ethanolamine modified KMnF3@Zn-MOF-74 mixed matrix membrane:

[0045] Step 1: Preparation of KMnF3@Zn-MOF-74: 1.5g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) was dissolved in a first mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water. 0.5g of KMnF3 nanoparticles were added and stirred to obtain mixture A. 0.5g of 2,5-dihydroxyterephthalic acid (H4DOBDC) was dissolved in a second mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water to obtain ligand solution B. Ligand solution B was added to mixture A and stirred for 30min. The mixture was then transferred to a reaction vessel and reacted at 100℃ for 24 hours. After washing three times with methanol (CH3OH), it was dried in a vacuum drying oven at 100℃ for 24 hours to obtain KMnF3@Zn-MOF-74 filler.

[0046] Step 2: Preparation of modified KMnF3@Zn-MOF-74: Disperse 0.1g KMnF3@Zn-MOF-74 in 20mL ethanol solution, add 0.5 wt.% ethanolamine, stir magnetically at room temperature for 20-24 hours, centrifuge, wash with ethanol 2-3 times, and vacuum dry for 18-24 hours to obtain ethanolamine modified KMnF3@Zn-MOF-74 filler;

[0047] Step 3, Preparation of Pebax-1657: Weigh 51.28g of ethanol and 15.21g of distilled water and mix them. Then add 2.19g of Pebax-1657 and stir at 75℃ for 5 hours to completely dissolve it, so as to obtain a Pebax-1657 solution.

[0048] Step 4: Preparation of 3wt.% modified KMnF3@Zn-MOF-74 mixed matrix membrane: Weigh 3wt.% modified KMnF3@Zn-MOF-74 filler and Pebax-1657 solution to prepare casting solution. Stir at 500r / min for 1 hour to disperse it evenly. After ultrasonic degassing for 25min, let it stand for 25min. Then pour it into a clean polytetrafluoroethylene mold. Then put the membrane into a constant temperature oven and dry it at 60℃ for 24 hours. Finally, continue drying in a vacuum oven for 24 hours to obtain the functionalized KMnF3@Zn-MOF-74 mixed matrix membrane.

[0049] like Figure 1 As shown in the XRD pattern, the KMnF3@Zn-MOF-74 composite material clearly retains all the strong characteristic peaks of the KMnF3 core and the low-angle characteristic peaks of the Zn-MOF-74 shell in Comparative Example 6, with no new impurity peaks appearing and no significant shift in the original peak positions. This indicates that the Zn-MOF-74 shell was successfully grown in situ and uniformly coated on the surface of the KMnF3 core, forming a stable core-shell structure. The coating process did not cause any phase transformation, decomposition, or chemical reaction in the KMnF3 core or the Zn-MOF-74 shell. The composite material maintains the independent crystal structures of the two components while achieving a tight interfacial bond. The XRD pattern of the modified KMnF3@Zn-MOF-74 almost completely overlaps with that of the unmodified KMnF3@Zn-MOF-74, indicating that the amination modification process was mild and did not damage the crystal structure of the composite, thus confirming the stability of the original composite synthesis.

[0050] like Figure 2 As shown, 3300 cm -1 The nearby peaks correspond to the -NH vibration in the framework. Compared to Comparative Example 1, the modified material shows a higher peak at 3300 cm⁻¹. -1 A significant enhancement of the -NH stretching vibration was observed in the region, and this enhancement gradually increased with increasing concentration from Examples 1 to 4, resulting in a broadened and stronger absorption peak. This indicates successful amination of the material. The interaction between -NH and C=O in the examples led to a higher absorption peak at 1650 cm⁻¹. -1 The C=O peak intensity increased. Furthermore, the CH absorption intensity in the figure also increased with increasing concentration in the examples. This indicates that a large number of methylene groups were introduced via ethanolamine, further demonstrating successful amination. These peak changes indicate that ethanolamine coordinated with the metal center or underwent hydrogen bonding, thus achieving successful modification of KMnF3@Zn-MOF-74.

[0051] The separation performance of the above-mentioned mixed matrix membrane was tested to be PCO2=78.21 Barrer and CO2 / N2 selectivity 80.46.

[0052] Example 2:

[0053] Preparation of KMnF3: 0.416 g manganese chloride tetrahydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were magnetically stirred at room temperature for 20-30 min to form a first microemulsion. 0.592 g potassium fluoride dihydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were weighed and magnetically stirred at room temperature for 20-30 min to obtain a second microemulsion. The second microemulsion was slowly added dropwise to the first microemulsion to prepare a mixture. The mixture was reacted for 5 min, and then an excess of CHCl3 / CH3OH mixed solution was added to terminate the reaction. The mixture was washed repeatedly with methanol and deionized water, centrifuged, and dried at 60-80 °C for 12-24 hours to obtain KMnF3 nanoparticles.

[0054] Preparation method of ethanolamine modified KMnF3@Zn-MOF-74 mixed matrix membrane:

[0055] Step 1: Preparation of KMnF3@Zn-MOF-74: 1.5g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) was dissolved in a first mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water. 0.5g of KMnF3 nanoparticles were added and stirred to obtain mixture A. 0.5g of 2,5-dihydroxyterephthalic acid (H4DOBDC) was dissolved in a second mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water to obtain ligand solution B. Ligand solution B was added to mixture A and stirred for 30min. The mixture was then transferred to a reaction vessel and reacted at 100℃ for 24 hours. After washing three times with methanol (CH3OH), it was dried in a vacuum drying oven at 100℃ for 24 hours to obtain KMnF3@Zn-MOF-74 filler.

[0056] Step 2: Preparation of modified KMnF3@Zn-MOF-74: Disperse 0.1g KMnF3@Zn-MOF-74 in 20mL ethanol solution, add 0.5 wt.% ethanolamine, stir magnetically at room temperature for 20-24 hours, centrifuge, wash with ethanol 2-3 times, and vacuum dry for 18-24 hours to obtain ethanolamine modified KMnF3@Zn-MOF-74 filler;

[0057] Step 3, Preparation of Pebax-1657: Weigh 51.28g of ethanol and 15.21g of distilled water and mix them. Then add 2.19g of Pebax-1657 and stir at 75℃ for 5 hours to completely dissolve it, so as to obtain a Pebax-1657 solution.

[0058] Step 4: Preparation of 5 wt.% modified KMnF3@Zn-MOF-74 mixed matrix membrane: Weigh 5 wt.% modified KMnF3@Zn-MOF-74 filler and Pebax-1657 solution to prepare casting solution. Stir at 500 r / min for 1 hour to disperse it evenly. After ultrasonic degassing for 25 min, let it stand for 25 min, and then pour it into a clean polytetrafluoroethylene mold. Then put the membrane into a constant temperature oven and dry it at 60℃ for 24 hours. Finally, continue drying in a vacuum oven for 24 hours to obtain the functionalized KMnF3@Zn-MOF-74 mixed matrix membrane.

[0059] The separation performance of the above-mentioned mixed matrix membrane was tested to be PCO2=80.56 Barrer and CO2 / N2 selectivity 83.27.

[0060] Example 3:

[0061] Preparation of KMnF3: 0.416 g manganese chloride tetrahydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were magnetically stirred at room temperature for 20-30 min to form a first microemulsion. 0.592 g potassium fluoride dihydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were weighed and magnetically stirred at room temperature for 20-30 min to obtain a second microemulsion. The second microemulsion was slowly added dropwise to the first microemulsion to prepare a mixture. The mixture was reacted for 5 min, and then an excess of CHCl3 / CH3OH mixed solution was added to terminate the reaction. The mixture was washed repeatedly with methanol and deionized water, centrifuged, and dried at 60-80 °C for 12-24 hours to obtain KMnF3 nanoparticles.

[0062] Preparation method of ethanolamine modified KMnF3@Zn-MOF-74 mixed matrix membrane:

[0063] Step 1: Preparation of KMnF3@Zn-MOF-74: 1.5g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) was dissolved in a first mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water. 0.5g of KMnF3 nanoparticles were added and stirred to obtain mixture A. 0.5g of 2,5-dihydroxyterephthalic acid (H4DOBDC) was dissolved in a second mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water to obtain ligand solution B. Ligand solution B was added to mixture A and stirred for 30min. The mixture was then transferred to a reaction vessel and reacted at 100℃ for 24 hours. After washing three times with methanol (CH3OH), it was dried in a vacuum drying oven at 100℃ for 24 hours to obtain KMnF3@Zn-MOF-74 filler.

[0064] Step 2: Preparation of modified KMnF3@Zn-MOF-74: Disperse 0.1g KMnF3@Zn-MOF-74 in 20mL ethanol solution, add 0.5 wt.% ethanolamine, stir magnetically at room temperature for 20-24 hours, centrifuge, wash with ethanol 2-3 times, and vacuum dry for 18-24 hours to obtain ethanolamine modified KMnF3@Zn-MOF-74 filler;

[0065] Step 3, Preparation of Pebax-1657: Weigh 51.28g of ethanol and 15.21g of distilled water and mix them. Then add 2.19g of Pebax-1657 and stir at 75℃ for 5 hours to completely dissolve it, so as to obtain a Pebax-1657 solution.

[0066] Step 4: Preparation of 7wt.% modified KMnF3@Zn-MOF-74 mixed matrix membrane: Weigh 7wt.% modified KMnF3@Zn-MOF-74 filler and Pebax-1657 solution to prepare casting solution. Stir at 500r / min for 1 hour to disperse it evenly. After ultrasonic degassing for 25min, let it stand for 25min. Then pour it into a clean polytetrafluoroethylene mold. After that, put the membrane into a constant temperature oven and dry it at 60℃ for 24 hours. Finally, continue to dry it in a vacuum oven for 24 hours to obtain the functionalized KMnF3@Zn-MOF-74 mixed matrix membrane.

[0067] The separation performance of the above-mentioned mixed matrix membrane was tested to be PCO2=93.35 Barrer and CO2 / N2 selectivity 86.73.

[0068] Example 4:

[0069] Preparation of KMnF3: 0.416 g manganese chloride tetrahydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were magnetically stirred at room temperature for 20-30 min to form a first microemulsion. 0.592 g potassium fluoride dihydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were weighed and magnetically stirred at room temperature for 20-30 min to obtain a second microemulsion. The second microemulsion was slowly added dropwise to the first microemulsion to prepare a mixture. The mixture was reacted for 5 min, and then an excess of CHCl3 / CH3OH mixed solution was added to terminate the reaction. The mixture was washed repeatedly with methanol and deionized water, centrifuged, and dried at 60-80 °C for 12-24 hours to obtain KMnF3 nanoparticles.

[0070] Preparation method of ethanolamine modified KMnF3@Zn-MOF-74 mixed matrix membrane:

[0071] Step 1: Preparation of KMnF3@Zn-MOF-74: 1.5g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) was dissolved in a first mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water. 0.5g of KMnF3 nanoparticles were added and stirred to obtain mixture A. 0.5g of 2,5-dihydroxyterephthalic acid (H4DOBDC) was dissolved in a second mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water to obtain ligand solution B. Ligand solution B was added to mixture A and stirred for 30min. The mixture was then transferred to a reaction vessel and reacted at 100℃ for 24 hours. After washing three times with methanol (CH3OH), it was dried in a vacuum drying oven at 100℃ for 24 hours to obtain KMnF3@Zn-MOF-74 filler.

[0072] Step 2: Preparation of modified KMnF3@Zn-MOF-74: Disperse 0.1g KMnF3@Zn-MOF-74 in 20mL ethanol solution, add 0.5 wt.% ethanolamine, stir magnetically at room temperature for 20-24 hours, centrifuge, wash with ethanol 2-3 times, and vacuum dry for 18-24 hours to obtain ethanolamine modified KMnF3@Zn-MOF-74 filler;

[0073] Step 3, Preparation of Pebax-1657: Weigh 51.28g of ethanol and 15.21g of distilled water and mix them. Then add 2.19g of Pebax-1657 and stir at 75℃ for 5 hours to completely dissolve it, so as to obtain a Pebax-1657 solution.

[0074] Step 4: Preparation of 9wt.% modified KMnF3@Zn-MOF-74 mixed matrix membrane: Weigh 9wt.% of modified KMnF3@Zn-MOF-74 filler and Pebax-1657 solution to prepare casting solution. Stir at 500 r / min for 1 hour to disperse it evenly. After ultrasonic degassing for 25 min, let it stand for 25 min, and then pour it into a clean polytetrafluoroethylene mold. Then put the membrane into a constant temperature oven and dry it at 60℃ for 24 hours. Finally, continue drying in a vacuum oven for 24 hours to obtain the functionalized KMnF3@Zn-MOF-74 mixed matrix membrane.

[0075] The separation performance of the above-mentioned mixed matrix membrane was tested to be PCO2=96.27 Barrer and CO2 / N2 selectivity 80.61.

[0076] Comparative Example 1:

[0077] Pebax1657 hybrid matrix membrane preparation method:

[0078] Step 1: Preparation of casting solution: Weigh 51.18g of ethanol and 16.56g of distilled water and mix them. Then add 2.19g of Pebax-1657 and stir at 70℃ for 5 hours to completely dissolve it to obtain Pebax1657 casting solution.

[0079] Step 2: After ultrasonic degassing of the Pebax1657 casting solution for 20 minutes, let it stand for another 20 minutes, pour it into a clean polytetrafluoroethylene mold, place it in a constant temperature oven at 60°C for 24 hours, and then continue to dry it in a vacuum oven for 24 hours to obtain the Pebax1657 polymer film.

[0080] The separation performance of the above-mentioned mixed matrix membrane was tested to be PCO2=57.82 Barrer and CO2 / N2 selectivity 40.75.

[0081] Comparative Example 2:

[0082] Preparation of KMnF3: 0.416 g manganese chloride tetrahydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were magnetically stirred at room temperature for 20-30 min to form a first microemulsion. 0.592 g potassium fluoride dihydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were weighed and magnetically stirred at room temperature for 20-30 min to obtain a second microemulsion. The second microemulsion was slowly added dropwise to the first microemulsion to prepare a mixture. The mixture was reacted for 5 min, and then an excess of CHCl3 / CH3OH mixed solution was added to terminate the reaction. The mixture was washed repeatedly with methanol and deionized water, centrifuged, and dried at 60-80 °C for 12-24 hours to obtain KMnF3 nanoparticles.

[0083] Preparation method of KMnF3@Zn-MOF-74 hybrid matrix membrane:

[0084] Step 1: Preparation of KMnF3@Zn-MOF-74: 1.5g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) was dissolved in a first mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water. 0.5g of KMnF3 nanoparticles were added and stirred to obtain mixture A. 0.5g of 2,5-dihydroxyterephthalic acid (H4DOBDC) was dissolved in a second mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water to obtain ligand solution B. Ligand solution B was added to mixture A and stirred for 30min. The mixture was then transferred to a reaction vessel and reacted at 100℃ for 24 hours. After washing three times with methanol (CH3OH), it was dried in a vacuum drying oven at 100℃ for 24 hours to obtain KMnF3@Zn-MOF-74 filler.

[0085] Step 2, Preparation of Pebax-1657: Weigh 51.28g of ethanol and 15.21g of distilled water and mix them. Then add 2.19g of Pebax-1657 and stir at 75℃ for 5 hours to completely dissolve it, so as to obtain a Pebax-1657 solution.

[0086] Step 3: Preparation of 3wt.% KMnF3@Zn-MOF-74 mixed matrix membrane: Weigh 3wt.% KMnF3@Zn-MOF-74 filler and Pebax-1657 solution to prepare casting solution. Stir at 500 r / min for 1 hour to disperse it evenly. After ultrasonic degassing for 25 min, let it stand for 25 min, and then pour it into a clean polytetrafluoroethylene mold. Then put the membrane into a constant temperature oven and dry it at 60℃ for 24 hours. Finally, continue drying in a vacuum oven for 24 hours to obtain KMnF3@Zn-MOF-74 mixed matrix membrane.

[0087] The separation performance of the above-mentioned mixed matrix membrane was tested to be PCO2=60.91 Barrer and CO2 / N2 selectivity 70.56.

[0088] Comparative Example 3:

[0089] Preparation of KMnF3: 0.416 g manganese chloride tetrahydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were magnetically stirred at room temperature for 20-30 min to form a first microemulsion. 0.592 g potassium fluoride dihydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were weighed and magnetically stirred at room temperature for 20-30 min to obtain a second microemulsion. The second microemulsion was slowly added dropwise to the first microemulsion to prepare a mixture. The mixture was reacted for 5 min, and then an excess of CHCl3 / CH3OH mixed solution was added to terminate the reaction. The mixture was washed repeatedly with methanol and deionized water, centrifuged, and dried at 60-80 °C for 12-24 hours to obtain KMnF3 nanoparticles.

[0090] Preparation method of KMnF3@Zn-MOF-74 hybrid matrix membrane:

[0091] Step 1: Preparation of KMnF3@Zn-MOF-74: 1.5g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) was dissolved in a first mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water. 0.5g of KMnF3 nanoparticles were added and stirred to obtain mixture A. 0.5g of 2,5-dihydroxyterephthalic acid (H4DOBDC) was dissolved in a second mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water to obtain ligand solution B. Ligand solution B was added to mixture A and stirred for 30min. The mixture was then transferred to a reaction vessel and reacted at 100℃ for 24 hours. After washing three times with methanol (CH3OH), it was dried in a vacuum drying oven at 100℃ for 24 hours to obtain KMnF3@Zn-MOF-74 filler.

[0092] Step 2, Preparation of Pebax-1657: Weigh 51.28g of ethanol and 15.21g of distilled water and mix them. Then add 2.19g of Pebax-1657 and stir at 75℃ for 5 hours to completely dissolve it, so as to obtain a Pebax-1657 solution.

[0093] Step 3: Preparation of 5wt.% KMnF3@Zn-MOF-74 mixed matrix membrane: Weigh 5wt.% KMnF3@Zn-MOF-74 filler and Pebax-1657 solution to prepare casting solution. Stir at 500r / min for 1 hour to disperse it evenly. After ultrasonic degassing for 25min, let it stand for 25min. Then pour it into a clean polytetrafluoroethylene mold. After that, put the membrane into a constant temperature oven and dry it at 60℃ for 24 hours. Finally, continue to dry it in a vacuum oven for 24 hours to obtain KMnF3@Zn-MOF-74 mixed matrix membrane.

[0094] The separation performance of the above-mentioned mixed matrix membrane was tested to be PCO2=63.06 Barrer and CO2 / N2 selectivity 75.49.

[0095] Comparative Example 4:

[0096] Preparation of KMnF3: 0.416 g manganese chloride tetrahydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were magnetically stirred at room temperature for 20-30 min to form a first microemulsion. 0.592 g potassium fluoride dihydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were weighed and magnetically stirred at room temperature for 20-30 min to obtain a second microemulsion. The second microemulsion was slowly added dropwise to the first microemulsion to prepare a mixture. The mixture was reacted for 5 min, and then an excess of CHCl3 / CH3OH mixed solution was added to terminate the reaction. The mixture was washed repeatedly with methanol and deionized water, centrifuged, and dried at 60-80 °C for 12-24 hours to obtain KMnF3 nanoparticles.

[0097] Preparation method of KMnF3@Zn-MOF-74 hybrid matrix membrane:

[0098] Step 1: Preparation of KMnF3@Zn-MOF-74: 1.5g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) was dissolved in a first mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water. 0.5g of KMnF3 nanoparticles were added and stirred to obtain mixture A. 0.5g of 2,5-dihydroxyterephthalic acid (H4DOBDC) was dissolved in a second mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water to obtain ligand solution B. Ligand solution B was added to mixture A and stirred for 30min. The mixture was then transferred to a reaction vessel and reacted at 100℃ for 24 hours. After washing three times with methanol (CH3OH), it was dried in a vacuum drying oven at 100℃ for 24 hours to obtain KMnF3@Zn-MOF-74 filler.

[0099] Step 2, Preparation of Pebax-1657: Weigh 51.28g of ethanol and 15.21g of distilled water and mix them. Then add 2.19g of Pebax-1657 and stir at 75℃ for 5 hours to completely dissolve it, so as to obtain a Pebax-1657 solution.

[0100] Step 3: Preparation of 7wt.% KMnF3@Zn-MOF-74 mixed matrix membrane: Weigh 7wt.% KMnF3@Zn-MOF-74 filler and Pebax-1657 solution to prepare casting solution. Stir at 500r / min for 1 hour to disperse it evenly. After ultrasonic degassing for 25min, let it stand for 25min. Then pour it into a clean polytetrafluoroethylene mold. Then put the membrane into a constant temperature oven and dry it at 60℃ for 24 hours. Finally, continue drying in a vacuum oven for 24 hours to obtain KMnF3@Zn-MOF-74 mixed matrix membrane.

[0101] The separation performance of the above-mentioned mixed matrix membrane was tested to be PCO2=68.79 Barrer and CO2 / N2 selectivity 77.32.

[0102] Comparative Example 5:

[0103] Preparation of KMnF3: 0.416 g manganese chloride tetrahydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were magnetically stirred at room temperature for 20-30 min to form a first microemulsion. 0.592 g potassium fluoride dihydrate, 3 g hexadecyltrimethylammonium bromide, 3 mL 1-butanol, 15.5 mL octane, and 1.5 mL deionized water were weighed and magnetically stirred at room temperature for 20-30 min to obtain a second microemulsion. The second microemulsion was slowly added dropwise to the first microemulsion to prepare a mixture. The mixture was reacted for 5 min, and then an excess of CHCl3 / CH3OH mixed solution was added to terminate the reaction. The mixture was washed repeatedly with methanol and deionized water, centrifuged, and dried at 60-80 °C for 12-24 hours to obtain KMnF3 nanoparticles.

[0104] Preparation method of KMnF3@Zn-MOF-74 hybrid matrix membrane:

[0105] Step 1: Preparation of KMnF3@Zn-MOF-74: 1.5g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) was dissolved in a first mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water. 0.5g of KMnF3 nanoparticles were added and stirred to obtain mixture A. 0.5g of 2,5-dihydroxyterephthalic acid (H4DOBDC) was dissolved in a second mixed solvent of 30mL N,N-dimethylformamide solution (DMF) and 5mL water to obtain ligand solution B. Ligand solution B was added to mixture A and stirred for 30min. The mixture was then transferred to a reaction vessel and reacted at 100℃ for 24 hours. After washing three times with methanol (CH3OH), it was dried in a vacuum drying oven at 100℃ for 24 hours to obtain KMnF3@Zn-MOF-74 filler.

[0106] Step 2, Preparation of Pebax-1657: Weigh 51.28g of ethanol and 15.21g of distilled water and mix them. Then add 2.19g of Pebax-1657 and stir at 75℃ for 5 hours to completely dissolve it, so as to obtain a Pebax-1657 solution.

[0107] Step 3: Preparation of 9wt.% KMnF3@Zn-MOF-74 mixed matrix membrane: Weigh 9wt.% KMnF3@Zn-MOF-74 filler and Pebax-1657 solution to prepare casting solution. Stir at 500r / min for 1 hour to disperse it evenly. After ultrasonic degassing for 25min, let it stand for 25min. Then pour it into a clean polytetrafluoroethylene mold. Then put the membrane into a constant temperature oven and dry it at 60℃ for 24 hours. Finally, continue drying in a vacuum oven for 24 hours to obtain KMnF3@Zn-MOF-74 mixed matrix membrane.

[0108] The separation performance of the above-mentioned mixed matrix membrane was tested to be PCO2=70.96 Barrer and CO2 / N2 selectivity 73.81.

[0109] Comparative Example 6:

[0110] Preparation of Zn-MOF-74: 1.5 g of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) was dissolved in a first mixed solvent of 30 mL of N,N-dimethylformamide solution (DMF) and 5 mL of water to obtain mixture A; 0.5 g of 2,5-dihydroxyterephthalic acid (H4DOBDC) was dissolved in a second mixed solvent of 30 mL of N,N-dimethylformamide solution (DMF) and 5 mL of water to obtain ligand solution B; ligand solution B was added to mixture A and stirred for 30 min, then transferred to a reaction vessel and reacted at 100 °C for 24 h. After washing three times with methanol (CH3OH), it was dried in a vacuum drying oven at 100 °C for 24 h to obtain Zn-MOF-74 filler.

[0111] like Figure 1 As shown in the XRD pattern, the pure Zn-MOF-74 sample exhibits typical hexagonal MOF-74 characteristic diffraction peaks, mainly concentrated in the low-angle region. The XRD pattern of KMnF3@Zn-MOF-74 successfully retained the low-angle characteristic peaks of Zn-MOF-74 and the high-angle characteristic peaks of KMnF3, without any new impurity peaks appearing, and the original peak positions did not shift significantly. This indicates that the Zn-MOF-74 shell was successfully grown in situ and uniformly coated on the surface of the KMnF3 core, forming a stable core-shell structure.

[0112] Table 1 shows the CO2 permeability (Barrer) and CO2 / N2 selectivity correlation performance test results of the mixed matrix membranes prepared in Pebax-1657 by Comparative Examples 1-5 and Examples 1-4 using KMnF3@Zn-MOF-74 and modified KMnF3@Zn-MOF-74.

[0113] Table 1. Test results of the relevant properties of the hybrid matrix membranes prepared above.

[0114] name Filler content in Pebax (wt.%) Is it modified with ethanolamine? <![CDATA[CO2 Permeability Coefficient (Barrer)]]> <![CDATA[CO2 / N2 selectivity]]> Comparative Example 1 0 no 57.82 40.75 Comparative Example 2 3 no 60.91 70.56 Comparative Example 3 5 no 63.06 75.49 Comparative Example 4 7 no 68.79 77.32 Comparative Example 5 9 no 70.96 73.81 Example 1 3 yes 78.21 80.46 Example 2 5 yes 80.56 83.27 Example 3 7 yes 93.35 86.73 Example 4 9 yes 96.27 80.61

[0115] Conclusions: In Comparative Examples 2-5, the addition of KMnF3@Zn-MOF-74 to the membrane significantly improved CO2 permeability due to the open metal sites and one-dimensional pore structure of MOF, resulting in more rapid gas transport channels within the membrane. However, the unmodified KMnF3@Zn-MOF-74 exhibited weak interfacial bonding with the polymer, potentially leading to micropores or non-ideal interfaces, thus limiting further improvement in CO2 / N2 selectivity. In Examples 1-4, KMnF3, acting as an inorganic core, provided a stable heterogeneous nucleation interface for the epitaxial growth of Zn-MOF-74, resulting in a more uniform distribution of the Zn-MOF-74 shell. This effectively suppressed the aggregation of MOF particles in the membrane, improved the dispersibility and structural stability of the filler in the polymer matrix, and, after modification with ethanolamine, the -NH2 groups of ethanolamine could form stronger hydrogen bonds and interactions with Pebax segments, thereby significantly improving the interfacial compatibility between MOF and the polymer. Meanwhile, ethanolamine introduces additional CO2 affinity sites (-NH2), increasing CO2 solubility. The combined effect of interfacial densification and CO2 affinity allows the modified mixed matrix membrane to maintain high permeation flux while further enhancing CO2 / N2 selectivity. Specifically, the mixed matrix membrane with a modified KMnF3@Zn-MOF-74 content of 7 wt.% exhibits a separation performance of PCO2 = 93.35 Barrer and a CO2 / N2 selectivity of 86.73, demonstrating excellent permeability and selectivity.

[0116] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, those skilled in the art can make various improvements, modifications, or equivalent substitutions to the technical solutions and implementation methods of the present invention without departing from the spirit of the present invention, and all such improvements and modifications should fall within the protection scope of the present invention.

Claims

1. A method for preparing an ethanolamine-modified KMnF3@Zn-MOF-74 mixed matrix membrane, characterized in that, Includes the following steps: Step 1: Preparation of KMnF3@Zn-MOF-74 core-shell structured filler: Zinc nitrate hexahydrate was dissolved in a first mixed solvent of N,N-dimethylformamide and water, KMnF3 nanoparticles were added and stirred to obtain mixture A; 2,5-dihydroxyterephthalic acid was dissolved in a second mixed solvent of N,N-dimethylformamide and water to obtain ligand solution B; ligand solution B was added to mixture A, stirred evenly, and then transferred to a reaction vessel for reaction. After the reaction was completed, the mixture was washed and dried to obtain KMnF3@Zn-MOF-74 core-shell structured filler. Step 2: Preparation of ethanolamine-modified filler: The KMnF3@Zn-MOF-74 core-shell structure filler obtained in Step 1 was dispersed in anhydrous ethanol, ethanolamine was added, and the mixture was magnetically stirred at room temperature for 20-24 hours. After centrifugation, the filler was washed 2-3 times with anhydrous ethanol and vacuum dried for 18-24 hours to obtain the ethanolamine-modified KMnF3@Zn-MOF-74 core-shell structure filler. Step 3: Preparation of polymer casting solution: Pebax-1657 is uniformly dispersed in a mixed solvent of ethanol and water, heated and stirred until completely dissolved to obtain Pebax casting solution; Step 4: Preparation of the mixed matrix membrane: The ethanolamine-modified KMnF3@Zn-MOF-74 core-shell structure filler obtained in Step 2 is added to the Pebax casting solution obtained in Step 3, dispersed evenly, and stirred at room temperature for 1-1.5 hours. The resulting casting solution is cast onto a clean polytetrafluoroethylene plate and placed in a constant temperature oven at 60-85℃ for 18-24 hours. Then, it is placed in a vacuum oven and dried at 60-85℃ for another 18-24 hours to obtain the ethanolamine-modified KMnF3@Zn-MOF-74 mixed matrix membrane. The preparation method of the KMnF3 nanoparticles is as follows: Manganese chloride tetrahydrate, hexadecyltrimethylammonium bromide, 1-butanol, octane and deionized water are magnetically stirred at room temperature for 20-30 min to form a first microemulsion; potassium fluoride dihydrate, hexadecyltrimethylammonium bromide, 1-butanol, octane and deionized water are weighed and magnetically stirred at room temperature for 20-30 min to obtain a second microemulsion; the second microemulsion is slowly added dropwise to the first microemulsion to obtain a mixed solution; the mixture is reacted for 5 min and then an excess of CHCl3 / CH3OH mixed solution is added to terminate the reaction; the mixture is washed and centrifuged multiple times with methanol and deionized water, and dried at 60-80℃ for 12-24 hours to obtain KMnF3 nanoparticles; In step 1, the mass ratio of 2,5-dihydroxyterephthalic acid: zinc nitrate hexahydrate: KMnF3 nanoparticles: N,N-dimethylformamide: water is 1:2.5~3:1:90~120:20; In step 2, the amount of ethanolamine added is 0.1~1.0 wt.% of the total mass of anhydrous ethanol and ethanolamine; In step 3, the mass concentration of Pebax-1657 in the Pebax casting solution is 1%~5%; In step 4, the amount of ethanolamine-modified KMnF3@Zn-MOF-74 core-shell structure filler added is 3 wt.% to 9 wt.% of its mass as a percentage of the mass of the Pebax-1657 polymer.

2. The method for preparing an ethanolamine-modified KMnF3@Zn-MOF-74 mixed matrix membrane as described in claim 1, characterized in that, In step 3, the mass ratio of ethanol to water in the mixed solvent of ethanol and water is 6~9:4~1.

3. The method for preparing an ethanolamine-modified KMnF3@Zn-MOF-74 mixed matrix membrane as described in claim 1, characterized in that, When preparing the KMnF3 nanoparticles, the mass ratio of manganese chloride tetrahydrate: potassium fluoride dihydrate: hexadecyltrimethylammonium bromide: 1-butanol: octane: deionized water is 1:1.3~1.5:13~16:9~13:40~60:5~10.

4. An ethanolamine-modified KMnF3@Zn-MOF-74 hybrid matrix membrane, characterized in that, It is prepared by the preparation method described in any one of claims 1-3.

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