Gas separation membrane with semi-interpenetrating network structure as well as preparation method and application of gas separation membrane

Abstract

The invention discloses a gas separation membrane with a semi-interpenetrating network structure as well as a preparation method and application thereof, and belongs to the technical field of membrane separation. The preparation method of the gas separation membrane with the semi-interpenetrating network structure comprises the following steps: dispersing vinyl-modified metal organic polyhedrons in a solvent, performing ultrasonic treatment, adding polyether block copolyamide, polyethylene glycol diacrylate and an initiator, and reacting to obtain a membrane casting solution; and coating a substrate with the membrane casting solution, drying, and carrying out heat treatment to obtain the gas separation membrane with the semi-interpenetrating network structure. According to the preparation method, vinyl modified metal organic polyhedrons and polyethylene glycol diacrylate are subjected to free radical polymerization reaction in a polyether block copolyamide matrix in a thermal initiation mode, and the gas separation membrane with a semi-interpenetrating network structure is prepared and used for the CO2 separation process.

Description

Technical Field

[0001] This invention relates to the field of membrane separation technology, and in particular to a gas separation membrane with a semi-interpenetrating network structure, its preparation method, and its application. Background Technology

[0002] Global warming caused by greenhouse gases has become one of the most severe environmental challenges of the 21st century, with excessive CO2 emissions being a major driving factor. As a key pathway to achieving carbon neutrality, carbon capture urgently needs to develop novel separation methods that combine high efficiency and low energy consumption. Among various gas separation technologies, membrane separation technology is considered a promising solution due to its outstanding advantages such as low energy consumption, ease of operation, and environmental friendliness. Membrane materials are the core of membrane separation technology. Polyether block copolymers, as a current research hotspot for CO2 separation membranes, have the following advantages: on the one hand, flexible polyether segments impart excellent CO2 affinity to the material; on the other hand, rigid polyamide segments provide good mechanical strength. However, polyether block copolymer membranes are limited by the permeability-selectivity trade-off effect, restricting their application in the field of CO2 separation.

[0003] To further improve the CO2 separation performance of polyether block copolyamide membranes, numerous attempts have been made, such as blending with other polymers, introducing cross-linked structures, and adding inorganic nanoparticles to prepare mixed matrix membranes. However, physical blending may introduce non-selective interfacial defects due to differences in the compatibility of the two phases, resulting in limited or even decreased improvement in separation performance; if chemical cross-linking is not properly controlled, it is easy to form an overly dense, non-permeable structure due to excessive restriction of chain segment movement, which also makes it difficult to achieve an effective breakthrough in separation performance; when introducing inorganic nanoparticles, if the filler is unevenly dispersed or there are pores at the interface, defective channels will be formed for rapid gas passage, severely weakening the sieving effect and deteriorating the separation performance.

[0004] Therefore, there is an urgent need to provide a novel high-efficiency polyether block copolyamide film. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a gas separation membrane with a semi-interpenetrating network structure, its preparation method, and its applications. This invention utilizes a thermally initiated free radical polymerization reaction between vinyl-modified metal-organic polyhedra and polyethylene glycol diacrylate in a polyether block copolyamide matrix to prepare a gas separation membrane with a semi-interpenetrating network structure. Compared with existing physically blended, chemically crosslinked, and conventional mixed matrix membranes, the separation membrane prepared by this invention exhibits significantly improved CO2 separation performance. Through the copolymerization of vinyl-modified metal-organic polyhedra, uniform dispersion and strong interfacial bonding of the nanofiller are achieved in the matrix, effectively suppressing the formation of non-selective interfacial defects and effectively limiting the movement of polyether block copolyamide segments, thereby enhancing the membrane's CO2 / N2 sieving capacity. This structure further synergistically integrates the CO2 affinity of polyether segments, vinyl metal-organic polyhedra, and polyethylene glycol diacrylate with the stability of the crosslinked network, jointly promoting the efficient dissolution and rapid diffusion of CO2 within the membrane, thus achieving improved CO2 gas separation performance.

[0006] The technical solution of the present invention is as follows: The first aspect of this invention protects a method for preparing a gas separation membrane with a semi-interpenetrating network structure, comprising the following steps: Vinyl-modified metal-organic polyhedra are dispersed in a solvent, ultrasonically treated, and then polyether block copolyamide, polyethylene glycol diacrylate, and an initiator are added. The reaction is carried out to obtain a casting solution. The casting solution is coated onto a substrate, dried, and heat-treated to obtain a gas separation membrane with a semi-interpenetrating network structure.

[0007] Preferably, the vinyl-modified metal-organic polyhedron is obtained by adding acryloyl chloride to a zirconium-based metal-organic polyhedron solution, stirring, washing, and drying.

[0008] Preferably, the zirconium-based metal-organic polyhedron is obtained by mixing zirconium salt and 2-aminoterephthalic acid with a solvent, dissolving by ultrasonication, allowing to stand for reaction, and then washing.

[0009] Preferably, the mass ratio of the zirconium salt to the 2-aminoterephthalic acid is 1:3; The static reaction is carried out at a temperature of 60-65°C for 10-15 hours.

[0010] Preferably, the concentration of the zirconium-based organometallic polyhedron solution is 10 mg / mL; The volume ratio of the zirconium-based metal-organic polyhedron solution to the acryloyl chloride is 250:1.

[0011] Preferably, the mass ratio of the vinyl-modified metal-organic polyhedron to the solvent is 0.15~0.35:95.

[0012] Preferably, the mass ratio of the vinyl-modified metal-organic polyhedron to the polyether block copolyamide is 0.15~0.35:5; The polyether block copolyamide includes polyether block copolyamide 1657; Preferably, the mass ratio of the vinyl-modified metal-organic polyhedron to the polyethylene glycol diacrylate is 0.15~0.35:0.6~1.75; The average molecular weight of the polyethylene glycol diacrylate is one or more of 200Da, 400Da, 575Da, 600Da, and 700Da.

[0013] The mass ratio of the vinyl-modified metal-organic polyhedron to the initiator is 0.15~0.35:0.00375~0.00875; The reaction was carried out at a temperature of 80°C for 4 hours. The heat treatment was performed at a temperature of 85°C for 7 hours.

[0014] The second aspect of this invention protects a gas separation membrane with a semi-interpenetrating network structure prepared by the preparation method described in the first aspect above.

[0015] The third aspect of this invention protects the application of a gas separation membrane with a semi-interpenetrating network structure prepared by the preparation method described in the first aspect above, or the gas separation membrane with a semi-interpenetrating network structure described in the second aspect above, wherein the gas separation membrane is used to capture CO2 from flue gas.

[0016] The beneficial technical effects of this invention are as follows: This invention prepares a gas separation membrane with a semi-interpenetrating network structure by thermally initiating free radical polymerization of vinyl-modified metal-organic polyhedra and polyethylene glycol diacrylate in a polyether block copolyamide matrix. The semi-interpenetrating network structure consists of two or more polymers, one of which forms a cross-linked network, while another linear polymer runs through it without chemical cross-linking. The cross-linked network formed by polyethylene glycol diacrylate and vinyl-modified metal-organic polyhedra effectively restricts the movement of polyether block copolyamide segments, thereby enhancing the size sieving ability of gas molecules and improving the interfacial compatibility between the metal-organic polyhedra and the polymer matrix. Furthermore, the carboxyl and ester functional groups abundant in the cross-linked network of the gas separation membrane can be used for dipole... The dipole interaction induces strong physical adsorption of CO2, while exhibiting almost no interaction with nonpolar N2, significantly improving the CO2 / N2 solubility selectivity. Simultaneously, the polyether block copolyamide, serving as a continuous matrix, not only provides the necessary mechanical support and structural integrity for the membrane but also possesses high affinity and high permeability for CO2. In the semi-interpenetrating network structure, it synergistically works with the cross-linked network to further enhance the size sieving effect on gas molecules, thereby comprehensively improving gas separation performance.

[0017] The gas separation membrane provided by this invention adopts a green and environmentally friendly preparation process. The film formation process is easy to control and the film formation effect is good. Moreover, the gas separation membrane has the advantages of stable structure and reliable performance. It also exhibits excellent CO2 separation performance and can be widely used in CO2 / N2 separation scenarios. Attached Figure Description

[0018] Figure 1 The infrared spectrum of the gas separation membrane with a semi-interpenetrating network structure in Embodiment 2 of the present invention is shown.

[0019] Figure 2 This is the energy dispersive X-ray spectrum of the gas separation membrane with a semi-interpenetrating network structure in Embodiment 2 of the present invention.

[0020] Figure 3 This is a scanning electron microscope image of a gas separation membrane with a semi-interpenetrating network structure according to Embodiment 1 of the present invention. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the embodiments.

[0022] To address the problems of existing gas separation membranes, this invention provides a gas separation membrane with a semi-interpenetrating network structure, its preparation method, and its applications.

[0023] The first aspect of this invention provides a method for preparing a gas separation membrane with a semi-interpenetrating network structure, comprising the following steps: S1: The vinyl-modified metal-organic polyhedron is dispersed in a solvent, ultrasonically treated, and then polyether block copolyamide, polyethylene glycol diacrylate, and initiator are added. The reaction is carried out to obtain the casting solution. S2: The casting solution is coated onto the substrate, dried, and heat-treated to obtain a gas separation membrane with a semi-interpenetrating network structure.

[0024] In the gas separation membrane prepared by this invention, the cross-linked network formed by polyethylene glycol diacrylate and vinyl-modified zirconium-based metal-organic polyhedra not only effectively restricts the movement of polyether block copolyamide segments as a rigid network, thereby enhancing the size sieving ability of gas molecules, but also improves the interfacial compatibility between the metal-organic polyhedra and the polymer matrix. Furthermore, the carboxyl and ester functional groups abundant in this cross-linked network can be used through dipole... The dipole interaction induces strong physical adsorption of CO2, while exhibiting almost no interaction with nonpolar N2, significantly enhancing the CO2 / N2 solubility selectivity. Furthermore, the polyether block copolyamide, serving as a continuous matrix, not only provides the necessary mechanical support and structural integrity for the membrane but also possesses high affinity and permeability for CO2. In the semi-interpenetrating network structure, it synergistically works with the cross-linked network to further strengthen the size sieving effect on gas molecules, thereby comprehensively improving gas separation performance.

[0025] In some embodiments, in S1, the vinyl-modified metal-organic polyhedron is prepared by an amidation reaction of acryloyl chloride and zirconium-based metal-organic polyhedron.

[0026] In some embodiments, the vinyl-modified metal-organic polyhedron is prepared by adding acryloyl chloride to a zirconium-based metal-organic polyhedron solution, stirring slowly with a magnetic stirrer to obtain a vinyl-modified metal-organic polyhedron primary product, washing three times with dichloromethane to remove unreacted acryloyl chloride, and then drying in an oven.

[0027] In some embodiments, the zirconium-based metal-organic polyhedron is obtained by mixing zirconium salt with 2-aminoterephthalic acid in a solvent, dissolving it by ultrasonication, allowing it to stand and react to obtain a crude product, and then washing the crude product three times with N,N-dimethylacetamide to obtain the zirconium-based metal-organic polyhedron.

[0028] In some embodiments, the mass ratio of the zirconium salt to the 2-aminoterephthalic acid is 1:3; In some embodiments, the zirconium salt is zirconium dichloride.

[0029] In some embodiments, the solvent used in the preparation of zirconium-based organometallic polyhedra is a mixed solvent. Preferably, the mixed solvent is a mixture of N,N-dimethylacetamide and trace amounts of water; more preferably, the mixed solvent is a mixture of 1.0 mL of N,N-dimethylacetamide and 4 drops of trace amounts of water.

[0030] In some embodiments, during the preparation of zirconium-based organometallic polyhedra, the static reaction involves placing the sonicated solution in an oven for reaction. Preferably, the static reaction is carried out at a temperature of 60-65°C for 10-15 hours.

[0031] In some embodiments, the zirconium-based metal-organic polyhedron solution is obtained by dispersing zirconium-based metal-organic polyhedra in a solvent.

[0032] In some embodiments, the concentration of the zirconium-based metal-organic polyhedron solution is 10 mg / mL; In some embodiments, in the preparation of the vinyl-modified metal-organic polyhedron, the volume ratio of the zirconium-based metal-organic polyhedron solution to the acryloyl chloride is 250:1; the stirring time is 24 h; and the drying temperature is 40 °C.

[0033] In some embodiments, in S1, the mass ratio of the vinyl-modified metal-organic polyhedron to the solvent is 0.15 to 0.35:95.

[0034] In some embodiments, in S1, the solvent is a mixed solvent composed of ethanol and water, preferably, the mass ratio of ethanol to water is 11:6.

[0035] In some embodiments, in S1, the mass ratio of the vinyl-modified metal-organic polyhedron to the polyether block copolyamide is 0.15 to 0.35:5.

[0036] The polyether block copolyamide is composed of 60 wt% polyethylene oxide segments and 40 wt% polyamide segments.

[0037] In some embodiments, the polyether block copolyamide is polyether block copolyamide 1657.

[0038] In some embodiments, in S1, the mass ratio of the vinyl-modified metal-organic polyhedron to the polyethylene glycol diacrylate is 0.15~0.35:0.6~1.75.

[0039] Understandably, when the relative amounts of vinyl-modified metal-organic polyhedra, polyethylene glycol diacrylate, and polyether block copolyamide are inappropriate—for example, too much vinyl-modified metal-organic polyhedron can lead to an overly dense polymer network, causing phase separation, while too little can result in an overly loose network structure, affecting the overall stability of the material; similarly, too much polyethylene glycol diacrylate can also make the network structure too loose, while too little will affect network formation and stability. Therefore, it is necessary to rationally control the ratio of the three raw materials to balance the membrane strength and separation effect.

[0040] The average molecular weight of the polyethylene glycol diacrylate is one or more of 200Da, 400Da, 575Da, 600Da, and 700Da.

[0041] It is understood that the molecular weight of polyethylene glycol diacrylate in this invention affects the crosslinking density, chain segment flexibility, and free volume of the polymer network, thereby affecting the structural compactness and permeability of the gas separation membrane. Therefore, selecting polyethylene glycol diacrylate with a suitable molecular weight can better control the tightness of the network structure, achieving efficient and selective separation of target gases such as CO2 while ensuring the mechanical strength of the membrane material.

[0042] In some embodiments, in S1, the mass ratio of the vinyl-modified metal-organic polyhedron to the initiator is 0.15~0.35:0.00375~0.00875.

[0043] In some embodiments, the initiator is one or more of azobisisobutyronitrile or benzoyl peroxide.

[0044] In some embodiments, in S1, the reaction temperature is 80°C and the time is 4 hours.

[0045] In some embodiments, S1 further includes centrifuging the reaction solution after the reaction is completed, and using the centrifuged casting solution for S2.

[0046] In some embodiments, the drying time in S2 is 24 hours.

[0047] In some embodiments, in S2, the heat treatment temperature is 85°C and the time is 7 hours.

[0048] The second aspect of the present invention provides a gas separation membrane having a semi-interpenetrating network structure prepared by the preparation method described in the first aspect above.

[0049] The third aspect of the present invention provides an application of a gas separation membrane with a semi-interpenetrating network structure prepared by the preparation method described in the first aspect above, or a gas separation membrane with a semi-interpenetrating network structure described in the second aspect above, wherein the gas separation membrane is used to capture CO2 from flue gas.

[0050] This invention provides a gas separation membrane with a semi-interpenetrating network structure and its preparation method. The membrane prepared by this invention exhibits good separation selectivity. The method employs a green and environmentally friendly preparation process, which not only makes the membrane formation process easy to control and achieves good membrane formation results, but also provides the gas separation membrane with advantages such as structural stability and reliable performance. Furthermore, it demonstrates excellent CO2 selective separation performance and can be widely applied in CO2 / N2 separation scenarios.

[0051] The present invention will be further described below through examples and other means.

[0052] Example 1 A gas separation membrane with a semi-interpenetrating network structure is prepared by the following steps: Preparation of zirconium-based metal-organic polyhedra: 2-aminoterephthalic acid (0.005 g, 0.03 mmol) and zirconium dichloride (0.015 g, 0.05 mmol) were dissolved in a mixed solvent of N,N-dimethylacetamide (1.0 mL) and trace water (4 drops). After sonication, the mixture was placed in an oven at 65 °C and reacted for 10 h to obtain a crude product. The crude product was washed three times with N,N-dimethylacetamide to prepare zirconium-based metal-organic polyhedra.

[0053] Preparation of vinyl-modified metal-organic polyhedra: 50 mg of the zirconium-based metal-organic polyhedra (0.022 mmol) prepared above were dispersed in 5 mL of dichloromethane, followed by the addition of 20 μL of acryloyl chloride (0.26 mmol). The mixture was slowly stirred with a magnetic stirrer for 24 h to obtain the initial product of vinyl-modified metal-organic polyhedra. The product was then washed three times with dichloromethane to remove unreacted acryloyl chloride, and then dried in an oven at 40 °C to obtain vinyl-modified metal-organic polyhedra particles.

[0054] 0.35 g of the vinyl-modified metal-organic polyhedron particles prepared above were added to 95 g of a mixed solvent of ethanol and water (ethanol to water mass ratio of 11:6), and sonicated for 30 min. Then, 5 g of polyether block copolyamide (selected from Pebax by Arkema) was added. ® MH 1657), 1.4 g polyethylene glycol diacrylate (average molecular weight 575 Da) and 0.00875 g azobisisobutyronitrile were reacted at 80 °C for 4 h, and centrifuged at 9000 r / min for 5 min to obtain the casting solution.

[0055] The casting solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 24 hours, and then heat-treated in an 85°C oven for 7 hours to obtain a gas separation membrane with a thickness of 35 mm. .

[0056] Example 2 A gas separation membrane with a semi-interpenetrating network structure is prepared by the following steps: Vinyl-modified metal-organic polyhedron particles were prepared according to the method described in Example 1.

[0057] 0.2 g of the vinyl-modified metal-organic polyhedron particles prepared above were added to 95 g of a mixed solvent of ethanol and water (ethanol to water mass ratio of 11:6). After sonication for 30 min, 5 g of polyether block copolyamide (this raw material is the same as in Example 1), 0.8 g of polyethylene glycol diacrylate (average molecular weight 575 Da) and 0.005 g of azobisisobutyronitrile were added. The mixture was reacted at 80 °C for 4 h, and centrifuged at 9000 r / min for 5 min to obtain the casting solution.

[0058] The casting solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 24 hours, and then heat-treated in an 85°C oven for 7 hours to obtain a gas separation membrane with a thickness of 40 mm. .

[0059] Example 3 A gas separation membrane with a semi-interpenetrating network structure is prepared by the following steps: Vinyl-modified metal-organic polyhedron particles were prepared according to the method described in Example 1.

[0060] 0.25 g of the vinyl-modified metal-organic polyhedron particles prepared above were added to 95 g of a mixed solvent of ethanol and water (ethanol to water mass ratio of 11:6). After sonication for 30 min, 5 g of polyether block copolyamide (this raw material is the same as in Example 1), 1 g of polyethylene glycol diacrylate (average molecular weight 575 Da) and 0.00625 g of azobisisobutyronitrile were added. The mixture was reacted at 80 °C for 4 h, and centrifuged at 9000 r / min for 5 min to obtain the casting solution.

[0061] The casting solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 24 hours, and then heat-treated in an 85°C oven for 7 hours to obtain a gas separation membrane with a thickness of 36 mm. .

[0062] Example 4 A gas separation membrane with a semi-interpenetrating network structure is prepared by the following steps: Vinyl-modified metal-organic polyhedron particles were prepared according to the method described in Example 1.

[0063] 0.2 g of the vinyl-modified metal-organic polyhedron particles prepared above were added to 95 g of a mixed solvent of ethanol and water (ethanol to water mass ratio of 11:6). After sonication for 30 min, 5 g of polyether block copolyamide (this raw material is the same as in Example 1), 0.8 g of polyethylene glycol diacrylate (average molecular weight 200 Da) and 0.005 g of azobisisobutyronitrile were added. The mixture was reacted at 80 °C for 4 h, and centrifuged at 9000 r / min for 5 min to obtain the casting solution.

[0064] The casting solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 24 hours, and then heat-treated in an 85°C oven for 7 hours to obtain a gas separation membrane with a thickness of 51 μm. .

[0065] Example 5 A gas separation membrane with a semi-interpenetrating network structure is prepared by the following steps: Vinyl-modified metal-organic polyhedron particles were prepared according to the method described in Example 1.

[0066] 0.2 g of the vinyl-modified metal-organic polyhedron particles prepared above were added to 95 g of a mixed solvent of ethanol and water (ethanol to water mass ratio of 11:6). After sonication for 30 min, 5 g of polyether block copolyamide (this raw material is the same as in Example 1), 0.8 g of polyethylene glycol diacrylate (average molecular weight 400 Da) and 0.005 g of azobisisobutyronitrile were added. The mixture was reacted at 80 °C for 4 h, and centrifuged at 9000 r / min for 5 min to obtain the casting solution.

[0067] The casting solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 24 hours, and then heat-treated in an 85°C oven for 7 hours to obtain a gas separation membrane with a thickness of 53 μm. .

[0068] Example 6 A gas separation membrane with a semi-interpenetrating network structure is prepared by the following steps: Vinyl-modified metal-organic polyhedron particles were prepared according to the method described in Example 1.

[0069] 0.2 g of the vinyl-modified metal-organic polyhedron particles prepared above were added to 95 g of a mixed solvent of ethanol and water (ethanol to water mass ratio of 11:6). After sonication for 30 min, 5 g of polyether block copolyamide (this raw material is the same as in Example 1), 0.8 g of polyethylene glycol diacrylate (average molecular weight 600 Da) and 0.005 g of azobisisobutyronitrile were added. The mixture was reacted at 80 °C for 4 h, and centrifuged at 9000 r / min for 5 min to obtain the casting solution.

[0070] The casting solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 24 hours, and then heat-treated in an 85°C oven for 7 hours to obtain a gas separation membrane with a thickness of 48 μm. .

[0071] Example 7 A gas separation membrane with a semi-interpenetrating network structure is prepared by the following steps: Vinyl-modified metal-organic polyhedron particles were prepared according to the method described in Example 1.

[0072] 0.2 g of the vinyl-modified metal-organic polyhedron particles prepared above were added to 95 g of a mixed solvent of ethanol and water (ethanol to water mass ratio of 11:6). After sonication for 30 min, 5 g of polyether block copolyamide (this raw material is the same as in Example 1), 0.8 g of polyethylene glycol diacrylate (average molecular weight 700 Da) and 0.005 g of azobisisobutyronitrile were added. The mixture was reacted at 80 °C for 4 h, and centrifuged at 9000 r / min for 5 min to obtain the casting solution.

[0073] The casting solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 24 hours, and then heat-treated in an 85°C oven for 7 hours to obtain a gas separation membrane with a thickness of 55 mm. .

[0074] Comparative Example 1 The preparation method of a polyether block copolyamide film includes the following steps: Add 5g of polyether block copolyamide (the same raw material as in Example 1) to 95g of a mixed solvent of ethanol and water (the mass ratio of ethanol to water is 11:6), mix at 80°C for 4 h, centrifuge at 9000 r / min for 5 min to obtain the casting solution.

[0075] The casting solution was poured onto a polytetrafluoroethylene plate and dried at room temperature for 24 hours to obtain a polyether block copolyamide film with a thickness of 38 μm. . Comparative Example 2 A gas separation membrane is prepared by means of the following steps: 5 g of polyether block copolyamide (the same raw material as in Example 1), 0.82 g of polyethylene glycol diacrylate (average molecular weight 575 Da) and 0.0029 g of azobisisobutyronitrile were added to 95 g of a mixed solvent of ethanol and water (mass ratio of ethanol to water is 11:6), reacted at 80 °C for 4 h, and centrifuged at 9000 r / min for 5 min to obtain the casting solution.

[0076] The casting solution was poured onto a polytetrafluoroethylene plate, dried at room temperature for 24 hours, and then heat-treated in an 85°C oven for 7 hours to obtain a gas separation membrane with a thickness of 46 mm. .

[0077] Comparative Example 3 A polyether block copolyamide mixed matrix membrane is prepared by the following steps: 0.3 g of zirconium-based metal-organic polyhedron particles were added to 95 g of a mixed solvent of ethanol and water (ethanol to water mass ratio of 11:6), and sonicated for 30 min. Then, 5 g of polyether block copolyamide (the same raw material as in Example 1) was added, and the mixture was mixed at 80 °C for 4 h. After centrifugation at 9000 r / min for 5 min, the casting solution was obtained.

[0078] The casting solution was poured onto a polytetrafluoroethylene plate and dried at room temperature for 24 hours to obtain a mixed matrix membrane with a thickness of 49 μm. .

[0079] Comparative Example 4 The results are essentially the same as in Example 1, except that zirconium-based metal-organic polyhedra are used instead of vinyl-modified metal-organic polyhedra, and the film thickness is 52 μm. .

[0080] Test case (1) Characterization of membrane structure Figure 1 This is the infrared spectrum of the gas separation membrane with a semi-interpenetrating network structure according to Embodiment 2 of the present invention. As shown in the figure, 1262.49 cm⁻¹ -1 and 1101.01 cm -1 The peaks observed at [location missing] belong to the vibrational absorption peaks of the CO groups and the stretching vibration peaks of the COC groups in the polyether soft segment, respectively. The following three functional groups exist in the polyamide hard segment: the vibrational absorption peak of the -NH bond is at 3298.10 cm⁻¹. -1 , and 1636.44 cm -1 and 1724.59 cm -1 The characteristic peaks belong to amide-C=O and carbonyl-C=O groups, respectively. 772.37 cm⁻¹ -1 The absorption peak is the out-of-plane deformation vibration of =CH (aromatic hydrocarbon), indicating that the network polymer was successfully prepared.

[0081] Figure 2 This is the energy-dispersive X-ray spectrum of the gas separation membrane with a semi-interpenetrating network structure in Embodiment 2 of the present invention. As shown in the figure, the zirconium element is uniformly distributed, indicating that the vinyl metal-organic polyhedra have successfully participated in the construction of the cross-linked network.

[0082] Figure 3 This is a scanning electron microscope (SEM) image of the gas separation membrane with a semi-interpenetrating network structure according to Example 1 of the present invention. As can be seen from the image, the membrane surface is uniform and dense, indicating that the gas separation membrane with a semi-interpenetrating network structure was successfully prepared.

[0083] (2) Gas separation performance test The gas permeability (characterized by gas permeability coefficient) and selectivity of the membranes prepared in the embodiments and comparative examples of this invention were determined. The specific methods are as follows: The gas permeation test method is as follows: The gas separation membrane prepared in the examples or comparative examples is placed in a gas permeation cell, and the gas permeability of the membrane is measured using the constant volume pressure swing method. The gas permeability coefficient is determined using pure CO2 and N2 under conditions of 35°C and 0.3 MPa. P and ideal selectivity α i / j .

[0084] Gas permeability P The calculation formula is shown below: (1) In the formula: P The gas permeability coefficient (barrer, 1 barrer = 1 × 10⁻⁶) -10 cm 3 (STP)·cm / (cm 2 ·s·cmHg)), V Volume of the test chamber under the membrane (cm²) 3 ), l To test the thickness (cm) of the membrane. d The effective diameter (cm) of the test membrane. T For the test temperature (K), Δ P The pressure difference between the upstream and downstream sides of the membrane (cmHg). dp / dt The rate of change of gas pressure on the underside of the membrane over time (cmHg / s), dp / dt ) leak The leakage rate of gas on the upper and lower sides of the membrane under membrane vacuum (cmHg / s).

[0085] The selectivity can be calculated using equation (2): (2) In the formula: For the membrane to achieve ideal selectivity for CO2 and N2, This represents the CO2 permeability coefficient (barrer). This represents the permeability coefficient (barrer) of N2.

[0086] The test results are as follows: The gas separation membrane with a semi-interpenetrating network structure prepared in Example 1 has a CO2 permeability of 69 barrer and a CO2 / N2 selectivity of 79; the gas separation membrane with a semi-interpenetrating network structure prepared in Example 2 has a CO2 permeability of 54 barrer and a CO2 / N2 selectivity of 96; the gas separation membrane with a semi-interpenetrating network structure prepared in Example 3 has a CO2 permeability of 66 barrer and a CO2 / N2 selectivity of 88; the gas separation membrane with a semi-interpenetrating network structure prepared in Example 4 has a CO2 permeability of 50 barrer and a CO2 / N2 selectivity of 70; the gas separation membrane with a semi-interpenetrating network structure prepared in Example 5 has a CO2 permeability of 62 barrer and a CO2 / N2 selectivity of 67; the gas separation membrane with a semi-interpenetrating network structure prepared in Example 6 has a CO2 permeability of 76 barrer and a CO2 / N2 selectivity of 68; and the gas separation membrane with a semi-interpenetrating network structure prepared in Example 7 has a CO2 permeability of 85 barrer and a CO2 / N2 selectivity of 68.

[0087] The polyether block copolyamide gas separation membrane prepared in Comparative Example 1 had a CO2 permeability of 60 barrer and a CO2 / N2 selectivity of 57; the gas separation membrane prepared in Comparative Example 2 had a CO2 permeability of 78 barrer and a CO2 / N2 selectivity of 32; the polyether block copolyamide mixed matrix membrane prepared in Comparative Example 3 had a CO2 permeability of 54 barrer and a CO2 / N2 selectivity of 35. The metal-organic polyhedron composite membrane in Comparative Example 4, which used zirconium-based metal-organic polyhedra instead of vinyl-modified membranes, had a CO2 permeability of 73 barrer and a CO2 / N2 selectivity of 43.

[0088] Comparing the test results of the examples and the comparative examples, it can be seen that the gas separation membrane with a semi-interpenetrating network structure prepared in the examples has higher CO2 / N2 selectivity compared to the composite membrane prepared in the comparative example. This demonstrates that the semi-interpenetrating network structure jointly constructed by the vinyl-modified metal-organic polyhedron and polyethylene glycol diacrylate plays a crucial role in improving the gas separation performance of the membrane.

[0089] The above description is merely a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It is understood that other improvements and variations that are directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A method for preparing a gas separation membrane with a semi-interpenetrating network structure, characterized in that, Includes the following steps: Vinyl-modified metal-organic polyhedra are dispersed in a solvent, ultrasonically treated, and then polyether block copolyamide, polyethylene glycol diacrylate, and an initiator are added. The reaction is carried out to obtain a casting solution. The casting solution is coated onto a substrate, dried, and heat-treated to obtain a gas separation membrane with a semi-interpenetrating network structure.

2. The preparation method according to claim 1, characterized in that, The vinyl-modified organometallic polyhedron is obtained by adding acryloyl chloride to a zirconium-based organometallic polyhedron solution, stirring, washing, and drying.

3. The preparation method according to claim 2, characterized in that, The zirconium-based metal-organic polyhedron is obtained by mixing zirconium salt with 2-aminoterephthalic acid in a solvent, dissolving it by ultrasonication, allowing it to stand for reaction, and then washing it.

4. The preparation method according to claim 3, characterized in that, The mass ratio of the zirconium salt to the 2-aminoterephthalic acid is 1:3; The static reaction is carried out at a temperature of 60-65°C for 10-15 hours.

5. The preparation method according to claim 2, characterized in that, The concentration of the zirconium-based metal-organic polyhedron solution is 10 mg / mL; The volume ratio of the zirconium-based metal-organic polyhedron solution to the acryloyl chloride is 250:

1.

6. The preparation method according to claim 1, characterized in that, The mass ratio of the vinyl-modified metal-organic polyhedron to the solvent is 0.15~0.35:

95.

7. The preparation method according to claim 1, characterized in that, The mass ratio of the vinyl-modified metal-organic polyhedron to the polyether block copolyamide is 0.15~0.35:5; The polyether block copolyamide includes polyether block copolyamide 1657.

8. The preparation method according to claim 1, characterized in that, The mass ratio of the vinyl-modified metal-organic polyhedron to the polyethylene glycol diacrylate is 0.15~0.35:0.6~1.75; The average molecular weight of the polyethylene glycol diacrylate is one or more of 200 Da, 400 Da, 575 Da, 600 Da, and 700 Da; The mass ratio of the vinyl-modified metal-organic polyhedron to the initiator is 0.15~0.35:0.00375~0.00875; The reaction was carried out at a temperature of 80°C for 4 hours. The heat treatment was performed at a temperature of 85°C for 7 hours.

9. A gas separation membrane having a semi-interpenetrating network structure prepared by the preparation method according to any one of claims 1-8.

10. The application of a gas separation membrane with a semi-interpenetrating network structure prepared by the preparation method according to any one of claims 1-8, or the gas separation membrane with a semi-interpenetrating network structure according to claim 9, characterized in that, Used to capture CO2 from flue gas.

Images