A metal organic framework material composite film and a preparation method and application thereof

Abstract

This invention discloses a metal-organic framework (MOF) composite membrane, its preparation method, and its applications. The MOF composite membrane provided by this invention comprises a substrate, a hydrophilic layer, an adsorption layer, and a fixation layer stacked sequentially. The fixation layer coats the surface of the adsorption layer and is connected to the hydrophilic layer. The adsorption layer contains a metal-organic framework material (MOF), and the fixation layer contains a hydrophilic polymer. This invention uses a metal-organic framework material (MOF) as the adsorption layer. This material has abundant mesoporous structures and a high specific surface area, which is beneficial for improving the adsorption activity of the composite membrane. Through the cooperation of the hydrophilic layer and the fixation layer, the adsorption layer can be easily and efficiently fixed firmly in the membrane material, forming a composite membrane with good adsorption performance, high mechanical properties, and good stability. This composite membrane has good application prospects in gas adsorption and enrichment, especially in the adsorption and enrichment of krypton and / or xenon.

Description

Technical Field

[0001] This invention belongs to the field of membrane materials, and particularly relates to a metal-organic framework composite membrane, its preparation method, and its application. Background Technology

[0002] Metal-organic frameworks (MOFs) are porous materials with high specific surface areas, exhibiting excellent adsorption properties. However, traditional MOFs are typically synthesized in the form of crystalline powders, with crystallite sizes ranging from nanometers to hundreds of micrometers. This powder form significantly hinders their industrial applications, presenting problems such as: difficulty in powder handling, susceptibility to abrasion, potential obstruction or reduction of fluid flow, and loss of powder mass during preparation processes like powder purging. Current solutions involve bonding MOF powders with binders, including polymer binders such as PVA, PVB, and MC, as well as inorganic binders such as p-alumina and silica. These binders are then used in pressurized or non-pressurized processes to form MOF materials into spheres, particles, sheets, or monolithic forms. However, this molding process places high demands on the mechanical strength and stability of the formed material and presents challenges in industrial production, such as large space requirements and cumbersome processing.

[0003] Membrane enrichment separation technology is widely used in industrial production due to its simple operation, ease of maintenance, low energy consumption, and good separation effect. In particular, membrane enrichment separation technology offers the possibility of enriching and treating radioactive gaseous effluents in nuclear power plants and fuel reprocessing. For example, Kr-85 gas emits alpha rays with weak penetrating power; using membrane enrichment technology can solve the problem of inaccurate monitoring of trace gases, and the membrane design does not affect the penetration of radioactive gas rays. Therefore, this technology can provide technical support for accurate effluent monitoring by detectors through the enrichment effect of trace inert gases, and also provide accurate data support for environmental safety assessments of nuclear power plants. Membrane preparation is a crucial factor affecting the adsorption and enrichment effect.

[0004] Currently, existing membrane fabrication methods mainly include microwave-assisted thermal deposition, chemical vapor deposition, in-situ growth, secondary growth, and layer-by-layer assembly. These methods are mostly studied for the preparation of MOF membrane materials. However, these technologies have relatively harsh reaction conditions, complex processes, and high requirements for the membrane substrate, resulting in issues with the stability and compactness of the membrane structure. Summary of the Invention

[0005] In order to overcome at least one of the problems existing in the prior art, one of the objectives of the present invention is to provide a metal-organic framework composite membrane, which has good adsorption performance, good mechanical properties, good stability, high density, and simple preparation process, without the need for complex processes such as pressure molding.

[0006] The second objective of this invention is to provide a method for preparing the above-mentioned metal-organic framework composite film.

[0007] The third objective of this invention is to provide an application of the above-mentioned metal-organic framework composite membrane or the metal-organic framework composite membrane prepared by the above-mentioned preparation method in gas adsorption and enrichment.

[0008] The fourth objective of this invention is to provide a method for the adsorption and enrichment of krypton and / or xenon.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A first aspect of the present invention provides a metal-organic framework composite membrane, comprising a substrate, a hydrophilic layer, an adsorption layer, and a fixation layer disposed sequentially; the fixation layer covers the surface of the adsorption layer and is connected to the hydrophilic layer; the adsorption layer contains a metal-organic framework material, and the fixation layer contains a hydrophilic polymer; the hydrophilic polymer includes at least one selected from gelatin, hyaluronic acid gelatin, chitosan, hyaluronic acid, polyethylene glycol, polyacrylic acid and its derivatives, polyvinyl alcohol, polyoxyethylene, polyacrylamide, polyhydroxyethyl methacrylate, polyacrylic acid, or polymethacrylic acid.

[0011] The metal-organic framework composite membrane according to the first aspect of the present invention has at least the following beneficial effects:

[0012] In this invention, a hydrophilic layer is first formed on the substrate surface to improve the hydrophilicity and adhesion of the substrate, which is beneficial for the subsequent adhesion of the adsorption layer and the immobilization layer. Due to the hydrophilic layer, the composite membrane can use substrates with various properties, reducing the requirements for the membrane substrate. Without the hydrophilic layer, the adsorption layer and the immobilization layer are difficult to disperse uniformly and adhere to the substrate. The hydrophilic polymers in the immobilization layer are also prone to aggregation due to uneven distribution, leading to inhomogeneity in membrane material properties and poor material stability. Next, metal-organic carbide (MOF) materials are used as the adsorption layer. MOFs have abundant mesoporous structures and high specific surface area, making them suitable as adsorption materials. This invention improves the adsorption activity of the composite membrane. A fixing layer is placed on the surface of the adsorption layer. Due to the good adhesion between the hydrophilic polymer in the fixing layer and the hydrophilic layer, the fixing layer acts like a "seatbelt," enveloping the adsorption layer in contact with the hydrophilic layer and better securing the adsorption layer firmly within the membrane material, forming a composite membrane material containing carbonized MOFs. Furthermore, the hydrophilic polymers used in this invention all possess excellent hydrophilic properties, strong adhesion to the hydrophilic layer, and good air permeability and stability, without affecting the adsorption performance of the adsorption layer. While fixing the carbonized MOF particles in the adsorption layer, the adsorption activity of the carbonized MOFs is not affected. Through the design of the composite membrane structure of this invention, a MOF composite membrane with excellent adsorption performance is simply and efficiently prepared without the need for complex processes such as pressure molding. The preparation process is simple, and the resulting composite membrane has good mechanical properties, good stability, and high density, showing promising application prospects in the preparation of gas adsorption materials.

[0013] In some specific embodiments of the present invention, the raw materials for preparing the hydrophilic layer include at least one of polyacrylic acid, methanol, ethanol or propanol.

[0014] In some specific embodiments of the present invention, the substrate material includes at least one of polyethylene terephthalate, silicon substrate, aluminum foil, or plastic substrate.

[0015] In some specific embodiments of the present invention, the mass ratio of the metal-organic carbide material to the hydrophilic polymer is 1:(0.1 to 1.2).

[0016] In some specific embodiments of the present invention, the thickness of the hydrophilic layer is 10–50 nm.

[0017] In some specific embodiments of the present invention, the thickness of the adsorption layer is ≥30nm.

[0018] In some specific embodiments of the present invention, the thickness of the fixing layer is 30 to 200 nm.

[0019] A second aspect of the present invention provides a method for preparing a metal-organic framework composite film, comprising the following steps:

[0020] S1. Take a substrate and apply the raw materials for preparing the hydrophilic layer to the surface of the substrate to form a hydrophilic layer;

[0021] S2. Apply a first dispersion containing a metal-organic framework material to the hydrophilic layer, and then dry it to form an adsorption layer;

[0022] S3. Apply a second dispersion containing a hydrophilic polymer to the adsorption layer, then dry it to form a fixed layer, and obtain the metal-organic framework composite film;

[0023] The composition of the metal-organic framework composite membrane is as described in the first aspect of the present invention.

[0024] The preparation method according to the second aspect of the present invention has at least the following beneficial effects:

[0025] Since carbonized MOFs are prone to agglomeration, which affects the uniformity of membrane material performance, preparing carbonized MOFs into a dispersion can improve their dispersibility. An adsorption layer can be obtained through a simple drying method. Then, a dispersion containing a hydrophilic polymer is applied to the adsorption layer. The hydrophilic polymer can form intermolecular forces with the hydrophilic layer to achieve good adhesion, thereby fixing the adsorption layer. This preparation process is simple, requires low equipment requirements, and the resulting composite membrane has good adsorption, stability, and mechanical properties.

[0026] In some specific embodiments of the present invention, the solvent in the first dispersion is a first solvent, which includes volatile alcohol solvents.

[0027] In some specific embodiments of the present invention, the concentration of the metal-organic carbide material in the first dispersion is 20-100 mg / mL.

[0028] In some specific embodiments of the present invention, the solvent in the second dispersion is a second solvent, which includes water, volatile alcohol solvents, or combinations thereof.

[0029] In some specific embodiments of the present invention, the concentration of the hydrophilic polymer in the second dispersion is 1 to 8 wt%.

[0030] In some specific embodiments of the present invention, in step S2, the carbide metal-organic framework material is obtained by carbonizing a metal-organic framework material.

[0031] In some specific embodiments of the present invention, the carbonization temperature is 500–1200°C.

[0032] In some specific embodiments of the present invention, the heating rate of the carbonization treatment is 1 to 10 °C / min.

[0033] In some specific embodiments of the present invention, the carbonization treatment time is 0.5 to 5 hours.

[0034] In some specific embodiments of the present invention, in step S2, the first dispersion is applied and then dried 1 to 10 times.

[0035] In some specific embodiments of the present invention, the drying temperature in steps S2 to S3 is independently 40 to 100°C.

[0036] In some specific embodiments of the present invention, the application method in steps S1 to S3 is independently selected from manual coating, electrostatic spraying, or a combination thereof.

[0037] The third aspect of the present invention provides an application of a metal-organic framework composite membrane as described in the first aspect of the present invention, or a metal-organic framework composite membrane prepared by the preparation method described in the second aspect of the present invention, in gas adsorption and enrichment.

[0038] The application according to the third aspect of the present invention has at least the following beneficial effects:

[0039] The metal-organic framework composite membrane of the present invention has good adsorption performance, especially for gases, and can achieve gas adsorption and enrichment. The membrane material has high density, good mechanical properties, and is not easy to peel off between different layers. The overall material has strong adhesion, good uniformity, and controllable thickness. Using this composite membrane for gas adsorption and enrichment can not only achieve good gas adsorption and enrichment effect, but also has good mechanical properties and long service life.

[0040] In some specific embodiments of the present invention, the gas includes an inert gas; in some more specific embodiments of the present invention, the gas includes krypton and / or xenon.

[0041] The adsorption layer of the composite membrane material of the present invention contains carbonized MOFs material. The carbonized MOFs material has a specific pore structure and pore size, and has a good adsorption effect on inert gases, especially krypton and / or xenon, and can be used for the adsorption and enrichment of krypton and / or xenon.

[0042] The fourth aspect of the present invention provides a method for adsorption and enrichment of krypton and / or xenon, using the metal-organic framework composite membrane described in the first aspect of the present invention, or the metal-organic framework composite membrane prepared by the preparation method described in the second aspect of the present invention, as an adsorbent to adsorb a mixed gas containing krypton and / or xenon, thereby achieving enrichment of krypton and / or xenon.

[0043] The adsorption enrichment method according to the fourth aspect of the present invention has at least the following beneficial effects:

[0044] The metal-organic framework composite membrane of the present invention has a good adsorption and enrichment effect on krypton and / or xenon. Using it as an adsorbent, krypton and / or xenon in the mixed gas can be removed, thereby achieving effective adsorption and enrichment of krypton and / or xenon in the mixed gas. Attached Figure Description

[0045] Figure 1 This is an optical microscope image of the composite film material in Experiment Example 1.

[0046] Figure 2 An optical microscope image of the composite film material used in Comparative Example 1.

[0047] Figure 3 This is a SEM image of the cross-section of the gelatin layer in Experiment Example 1.

[0048] Figure 4 The adsorption performance curves of CZIF-650, CZIF-800, CZIF-950 and uncarbonized ZIF-8 for krypton are shown.

[0049] Figure 5 The adsorption performance curves of CZIF-650, CZIF-800, CZIF-950 and uncarbonized ZIF-8 for xenon are shown.

[0050] Figure 6 The graph shows the adsorption performance of carbonized ZIF-8 on krypton and xenon before and after mixing with gelatin.

[0051] Figure 7 This is a flowchart illustrating the preparation process of the metal-organic framework composite membrane in Example 1.

[0052] Figure 8 This is a SEM image of the metal-organic framework composite membrane of Example 2.

[0053] Figure 9 This is a SEM image of the metal-organic framework composite membrane of Example 3.

[0054] Figure 10 The adsorption performance curves of krypton on the metal-organic framework composite membrane and PET substrate material in Examples 2-3 are shown.

[0055] Figure 11 The adsorption performance curves of xenon on the metal-organic framework composite membrane and PET substrate material in Examples 2 and 3 are shown. Detailed Implementation

[0056] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0057] A first aspect of the present invention provides a metal-organic framework composite film, comprising a substrate, a hydrophilic layer, an adsorption layer, and a fixation layer disposed sequentially; the fixation layer covers the surface of the adsorption layer and is connected to the hydrophilic layer; the adsorption layer contains a metal-organic framework material, and the fixation layer contains a hydrophilic polymer; the hydrophilic polymer includes at least one of gelatin, hyaluronic acid gelatin, chitosan, hyaluronic acid, polyethylene glycol, polyacrylic acid and its derivatives, polyvinyl alcohol, polyoxyethylene, polyacrylamide, polyhydroxyethyl methacrylate, polyacrylic acid, or polymethacrylic acid.

[0058] In this embodiment of the invention, a hydrophilic layer is first formed on the substrate surface to improve the hydrophilicity and adhesion of the substrate surface, which is beneficial to the subsequent adhesion of the adsorption layer and the immobilization layer. Due to the presence of the hydrophilic layer, the composite membrane can use substrates with various properties, reducing the requirements for the membrane substrate. Without the hydrophilic layer, the adsorption layer and the immobilization layer are difficult to disperse uniformly and adhere to the substrate. The hydrophilic polymer in the immobilization layer is also prone to aggregation due to uneven distribution, leading to inhomogeneity of membrane material properties and poor material stability. Next, metal-organic frameworks (MOFs) are used as the adsorption layer. MOFs have abundant mesoporous structures and high specific surface area, making them suitable as adsorption materials. The material is beneficial for improving the adsorption activity of the composite membrane. A fixing layer is set on the surface of the adsorption layer. Due to the good adhesion between the hydrophilic polymer in the fixing layer and the hydrophilic layer, the fixing layer acts like a "seatbelt," wrapping the adsorption layer in contact with the hydrophilic layer and better fixing the adsorption layer firmly in the membrane material, forming a composite membrane material containing carbonized MOFs. Furthermore, the hydrophilic polymers used in this invention all have good hydrophilic properties, strong adhesion to the hydrophilic layer, and good air permeability and stability, without affecting the adsorption performance of the adsorption layer. While fixing the carbonized MOF particles in the adsorption layer, it does not affect the adsorption activity of the carbonized MOFs. Through the design of the composite membrane structure of this invention, a MOF composite membrane with good adsorption performance is simply and efficiently prepared without the need for complex processes such as pressure molding. The preparation process is simple, and the resulting composite membrane has good mechanical properties, good stability, and high density, showing good application prospects in the preparation of gas adsorption materials.

[0059] In some embodiments of the present invention, the metal-organic carbide material is in the form of granules.

[0060] By setting the hydrophilic layer and the immobilization layer of the present invention, particulate metal-organic framework materials can be made into membrane materials, thereby broadening the industrial application of MOF materials and giving full play to the excellent adsorption performance of MOF materials.

[0061] In some embodiments of the present invention, the hydrophilic polymer includes at least one of gelatin, hyaluronic acid, chitosan, hyaluronic acid, polyethylene glycol, polyhydroxyethyl methacrylate, polyacrylic acid, or polymethacrylic acid; in some specific embodiments of the present invention, the hydrophilic polymer includes at least one of gelatin, hyaluronic acid, chitosan, hyaluronic acid, or polyethylene glycol; in some examples of the present invention, the hydrophilic polymer is selected from gelatin.

[0062] The hydrophilic polymer used in this invention not only has excellent hydrophilic properties but also good air permeability and stability. Its use as a fixing layer does not affect the adsorption performance of the adsorption layer. In particular, compared to other hydrophilic polymers, gelatin has better air permeability and stability. Using gelatin as the hydrophilic polymer in the fixing layer results in a composite membrane material with better adsorption performance and stronger mechanical properties.

[0063] In some embodiments of the present invention, the raw materials for preparing the hydrophilic layer include at least one of polyacrylic acid, methanol, ethanol or propanol; in some specific embodiments of the present invention, the raw materials for preparing the hydrophilic layer include polyacrylic acid, ethanol or a combination thereof.

[0064] Using the above-mentioned compounds with good hydrophilicity to prepare a hydrophilic layer on the substrate surface is beneficial to improving the hydrophilicity of the substrate surface and enhancing the adhesion between the substrate and the adsorption layer.

[0065] In some embodiments of the present invention, the substrate material includes at least one of polyethylene terephthalate (PET), silicon substrate, aluminum foil, or plastic substrate.

[0066] The material of the substrate can be selected according to actual needs or operating conditions; this invention does not impose specific limitations.

[0067] In some embodiments of the present invention, the mass ratio of metal-organic framework material to hydrophilic polymer is 1:(0.1-1.2); in some specific embodiments of the present invention, the mass ratio of metal-organic framework material to hydrophilic polymer is 1:(0.3-1); in some examples of the present invention, the mass ratio of metal-organic framework material to hydrophilic polymer is 1:(0.5-0.8). Non-limiting specific examples include 1:0.55, 1:0.6, 1:0.65, 1:0.7, or 1:0.75.

[0068] In some embodiments of the present invention, the thickness of the hydrophilic layer is 10–50 nm; in some specific embodiments of the present invention, the thickness of the hydrophilic layer is 15–45 nm; in some examples of the present invention, the thickness of the hydrophilic layer is 20–40 nm. Non-limiting specific examples include 22 nm, 25 nm, 28 nm, 30 nm, 32 nm, 35 nm, or 38 nm.

[0069] In some embodiments of the present invention, the thickness of the adsorption layer is ≥30 nm; in some specific embodiments of the present invention, the thickness of the adsorption layer is 30–20000 nm; in some examples of the present invention, the thickness of the adsorption layer is 100–15000 nm. Non-limiting specific examples include 200 nm, 400 nm, 800 nm, 1000 nm, 2000 nm, 5000 nm, 8000 nm, 10000 nm, or 12000 nm.

[0070] The thickness of the adsorption layer can be set according to actual needs. For example, by adding more metal-organic carbide framework materials, the thickness of the composite membrane can be controlled, and the uniformity of the composite membrane can be guaranteed. The preparation operation is simple and suitable for industrial production needs.

[0071] In some embodiments of the present invention, the thickness of the fixing layer is 30–200 nm; in some specific embodiments of the present invention, the thickness of the fixing layer is 50–180 nm; in some examples of the present invention, the thickness of the fixing layer is 80–150 nm. Non-limiting specific examples include 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, or 140 nm.

[0072] The purpose of setting the fixing layer is to fix the adsorption layer without affecting its adsorption performance. Therefore, it needs a certain degree of air permeability. Keeping its thickness within a certain range can achieve good air permeability and stability of the composite membrane.

[0073] A second aspect of this invention provides a method for preparing a metal-organic framework composite film according to the first aspect of this invention, comprising the following steps:

[0074] S1. Take a substrate and apply the raw materials for preparing the hydrophilic layer to the surface of the substrate to form a hydrophilic layer;

[0075] S2. Apply a first dispersion containing a metal-organic framework material to the hydrophilic layer, and then dry it to form an adsorption layer;

[0076] S3. Apply a second dispersion containing a hydrophilic polymer to the adsorption layer, then dry it to form a fixed layer, and obtain the metal-organic framework composite film;

[0077] The composition of the metal-organic framework composite membrane is as described in the first aspect of the embodiments of the present invention.

[0078] Since carbonized MOFs are prone to agglomeration, which affects the uniformity of membrane material performance, preparing carbonized MOFs into a dispersion can improve their dispersibility. An adsorption layer can be obtained through a simple drying method. Then, a dispersion containing a hydrophilic polymer is applied to the adsorption layer. The hydrophilic polymer can form intermolecular forces with the hydrophilic layer to achieve good adhesion, thereby fixing the adsorption layer. This preparation process is simple, requires low equipment requirements, and the resulting composite membrane has good adsorption, stability, and mechanical properties.

[0079] In some embodiments of the present invention, the solvent in the first dispersion is a first solvent, which includes volatile alcohol solvents; in some specific embodiments of the present invention, the first solvent includes at least one of methanol, ethanol, isopropanol, butanol or pentanol; in some specific embodiments of the present invention, the first solvent includes methanol, ethanol or a combination thereof; in some examples of the present invention, the first solvent is selected from ethanol.

[0080] Using volatile alcohol solvents as the first solvent can achieve good dispersion of carbonized MOFs in the first solvent. Moreover, alcohol solvents have good affinity with the hydrophilic layer, which is conducive to promoting the uniform distribution of carbonized MOFs on the hydrophilic layer, thereby obtaining a composite membrane with uniform thickness, uniform performance, and stable adsorption performance. Furthermore, volatile alcohol solvents have good volatility and fast drying speed, which is beneficial to improving the preparation efficiency of composite membranes.

[0081] In some embodiments of the present invention, the concentration of the metal-organic framework material in the first dispersion is 20–100 mg / mL; in some specific embodiments of the present invention, the concentration of the metal-organic framework material in the first dispersion is 30–80 mg / mL; in some examples of the present invention, the concentration of the metal-organic framework material in the first dispersion is 40–70 mg / mL. Non-limiting specific examples include 45 mg / mL, 50 mg / mL, 55 mg / mL, 60 mg / mL, or 65 mg / mL.

[0082] In some embodiments of the present invention, the metal carbide organic framework material is further ground before preparing the first dispersion.

[0083] Grinding can prevent the aggregation of metal-organic framework materials in the dispersion, thus avoiding affecting the uniform dispersion of the material in the dispersion.

[0084] In some embodiments of the present invention, the grinding time of the metal carbide organic framework material is 5 to 50 minutes; in some specific embodiments of the present invention, the grinding time of the metal carbide organic framework material is 10 to 40 minutes; in some examples of the present invention, the grinding time of the metal carbide organic framework material is 10 to 30 minutes; non-limiting specific examples include 15 minutes, 18 minutes, 20 minutes, 25 minutes or 28 minutes.

[0085] In some embodiments of the present invention, the solvent in the second dispersion is a second solvent, which includes water, volatile alcohol solvents, or combinations thereof; in some specific embodiments of the present invention, the second solvent includes water and volatile alcohol solvents; in some examples of the present invention, the second solvent includes water, and at least one of methanol, ethanol, isopropanol, butanol, or pentanol; in some examples of the present invention, the second solvent includes water and ethanol.

[0086] The hydrophilic polymer in the embodiments of the present invention has good solubility in water. Using water as a solvent can obtain a second dispersion with better dissolution effect. Volatile alcohol solvents have good volatility and fast drying speed, which is beneficial to improving the preparation efficiency of composite membranes.

[0087] In some embodiments of the present invention, the second solvent is selected from a mixed solution of water and a volatile alcohol solvent, wherein the volume ratio of water to volatile alcohol solvent is 1:(1-10); in some specific embodiments of the present invention, the volume ratio of water to volatile alcohol solvent is 1:(1.5-8); in some examples of the present invention, the volume ratio of water to volatile alcohol solvent is 1:(2-5). Non-limiting specific examples include 1:2.5, 1:3, 1:3.5, 1:4, or 1:4.5.

[0088] Adjusting the ratio of water to volatile alcohol solvents can regulate the solubility and volatility of the second dispersion, as well as its affinity and adhesion to the hydrophilic layer, thereby obtaining a composite membrane material with better overall performance.

[0089] In some embodiments of the present invention, the second solvent is selected from a mixed solution of water and ethanol, wherein the volume ratio of water to ethanol is 1:(1-10); in some specific embodiments of the present invention, the volume ratio of water to ethanol in the second solvent is 1:(1.5-8); in some examples of the present invention, the volume ratio of water to ethanol in the second solvent is 1:(2-5). Non-limiting specific examples include 1:2.5, 1:3, 1:3.5, 1:4, or 1:4.5.

[0090] In some embodiments of the present invention, the concentration of the hydrophilic polymer in the second dispersion is 1–8 wt%; in some specific embodiments of the present invention, the concentration of the hydrophilic polymer in the second dispersion is 1.5–6 wt%; in some examples of the present invention, the concentration of the hydrophilic polymer in the second dispersion is 2–4 wt%. Non-limiting specific examples include 2.2 wt%, 2.5 wt%, 2.8 wt%, 3 wt%, 3.2 wt%, 3.5 wt%, or 3.8 wt%.

[0091] In some embodiments of the present invention, in step S2, the carbide metal-organic framework material is obtained by carbonizing the metal-organic framework material.

[0092] By carbonizing MOFs, the material structure of MOFs can be changed to form carbonized MOFs with a loose and porous structure and a large specific surface area, thereby greatly increasing the adsorption sites of the material and giving it better adsorption performance.

[0093] In some embodiments of the present invention, the carbonization process is carried out in a protective gas atmosphere; in some specific embodiments of the present invention, the protective gas includes at least one of nitrogen, argon or helium; in some examples of the present invention, the protective gas is selected from nitrogen or argon.

[0094] In some embodiments of the present invention, the carbonization temperature is 500–1200°C; in some specific embodiments of the present invention, the carbonization temperature is 600–1100°C; in some examples of the present invention, the carbonization temperature is 650–1000°C. Non-limiting specific examples include 700°C, 750°C, 800°C, 850°C, 900°C, or 950°C.

[0095] The carbonization temperature affects the degree of carbonization of MOFs and the adsorption performance of the material. Within the carbonization temperature range of this invention, composite membrane materials with good adsorption effect can be obtained.

[0096] In some embodiments of the present invention, the heating rate of the carbonization treatment is 1–10 °C / min; in some specific embodiments of the present invention, the heating rate of the carbonization treatment is 2–8 °C / min; in some examples of the present invention, the heating rate of the carbonization treatment is 3–7 °C / min. Non-limiting specific examples include 3.5 °C / min, 4 °C / min, 4.5 °C / min, 5 °C / min, 5.5 °C / min, 6 °C / min, or 6.5 °C / min.

[0097] In some embodiments of the present invention, the carbonization treatment time is 0.5 to 5 hours; in some specific embodiments of the present invention, the carbonization treatment time is 0.8 to 4 hours; in some examples of the present invention, the carbonization treatment time is 1 to 3 hours. Non-limiting specific examples include 1.2 hours, 1.5 hours, 1.8 hours, 2 hours, 2.2 hours, 2.5 hours, or 2.8 hours.

[0098] In some embodiments of the present invention, the metal-organic framework material includes at least one of IRMOF material, ZIF material, CPL material, MIL material, PCN material or UiO material; in some specific embodiments of the present invention, the metal-organic framework material includes at least one of ZIF material, MIL material or UiO material; in some examples of the present invention, the metal-organic framework material is selected from ZIF material.

[0099] In some embodiments of the present invention, the ZIF material includes at least one of ZIF-8, ZIF-67, ZIF-7, ZIF-9, or ZIF-100; in some specific embodiments of the present invention, the ZIF material includes at least one of ZIF-8, ZIF-67, or ZIF-7; in some examples of the present invention, the ZIF material is selected from ZIF-8.

[0100] In some embodiments of the present invention, the step of applying the first dispersion and then drying in step S2 can be repeated; in some specific embodiments of the present invention, the number of times the first dispersion is applied and then dried in step S2 is 1 to 10; non-limiting specific examples include 2, 3, 4, 5, 6, 7, 8 or 9 times.

[0101] The thickness of the composite membrane can be adjusted by changing the number of times the first dispersion is applied in step S2. Therefore, the thickness of the composite membrane of the present invention is controllable and has good uniformity. The thickness adjustment method is simple and can adapt to the needs of different application scenarios.

[0102] In some embodiments of the present invention, the drying temperature in step S2 is 40–100°C; in some embodiments of the present invention, the drying temperature in step S2 is 50–90°C; in some embodiments of the present invention, the drying temperature in step S2 is 60–80°C; non-limiting specific examples include 65°C, 68°C, 70°C, 75°C, or 78°C.

[0103] In some embodiments of the present invention, the drying temperature in step S3 is 40-100°C; in some embodiments of the present invention, the drying temperature in step S3 is 50-90°C; in some embodiments of the present invention, the drying temperature in step S3 is 60-80°C; non-limiting specific examples include 65°C, 68°C, 70°C, 75°C or 78°C.

[0104] In some embodiments of the present invention, in step S1, the application method is selected from manual coating, electrostatic spraying, or a combination thereof. Specifically, the application in step S1 refers to applying the raw material for preparing the hydrophilic layer.

[0105] In some embodiments of the present invention, in step S2, the application method is selected from manual coating, electrostatic spraying, or a combination thereof. Specifically, the application in step S2 refers to the application of a first dispersion containing a metal-organic framework material.

[0106] In some embodiments of the present invention, in step S3, the application method is selected from manual coating, electrostatic spraying, or a combination thereof. Specifically, the application in step S3 refers to the application of a second dispersion containing a hydrophilic polymer.

[0107] In some embodiments of the present invention, the voltage for electrostatic spraying is 5 to 10 kV; non-limiting examples include 6 kV, 7 kV, 8 kV or 9 kV.

[0108] In some embodiments of the present invention, the nozzle speed for electrostatic spraying is 20 to 40 mm / min; non-limiting examples include 25 mm / min, 30 mm / min, or 35 mm / min.

[0109] In some embodiments of the invention, the rotation speed of the electrostatic spraying roller is 40 to 60 rpm; non-limiting examples include 45 rpm, 50 rpm, or 55 rpm.

[0110] In some embodiments of the present invention, the injection rate of electrostatic spraying is 4 to 8 mL / h; non-limiting examples include 5 mL / h, 6 mL / h or 7 mL / h.

[0111] The third aspect of the present invention provides a metal-organic framework composite membrane as described in the first aspect of the present invention, or a metal-organic framework composite membrane prepared by the preparation method of the second aspect of the present invention, for the application of gas adsorption and enrichment.

[0112] The metal-organic framework composite membrane of this invention has good adsorption performance, especially for gases, and can achieve gas adsorption and enrichment. The membrane material has high density, good mechanical properties, and is not easy to peel off between different layers. The overall adhesion of the material is strong, the uniformity is good, and the thickness is controllable. Using this composite membrane for gas adsorption and enrichment can not only achieve good gas adsorption and enrichment effect, but also has good mechanical properties and long service life.

[0113] In some embodiments of the present invention, the gas includes an inert gas; in some specific embodiments of the present invention, the gas includes krypton and / or xenon.

[0114] The adsorption layer of the composite membrane material of the present invention contains carbonized MOFs material. The carbonized MOFs material has a specific pore structure and pore size, and has a good adsorption effect on inert gases, especially krypton and / or xenon, and can be used for the adsorption and enrichment of krypton and / or xenon.

[0115] A fourth aspect of the present invention provides a method for adsorption and enrichment of krypton and / or xenon, using a metal-organic framework composite membrane of the first aspect of the present invention, or a metal-organic framework composite membrane prepared by the preparation method of the second aspect of the present invention, as an adsorbent to adsorb a mixed gas containing krypton and / or xenon, thereby achieving enrichment of krypton and / or xenon.

[0116] The metal-organic framework composite membrane of the present invention has a good adsorption and enrichment effect on krypton and / or xenon. Using it as an adsorbent, krypton and / or xenon in the mixed gas can be removed, thereby achieving effective adsorption and enrichment of krypton and / or xenon in the mixed gas.

[0117] The present invention will be further described below with reference to specific experimental examples, embodiments and comparative examples.

[0118] In the following test cases, examples, and comparative examples, performance tests were conducted using the following methods:

[0119] 1) Morphology test: The sample was observed using a scanning electron microscope (SEM).

[0120] 2) Krypton and Xenon Adsorption Performance Test: At room temperature (20-30℃), samples from the experimental examples, implementation examples and comparative examples were used as adsorbents to conduct adsorption tests on pure krypton and pure xenon gas respectively. The testing instrument was a fully automatic BET surface area analyzer.

[0121] Experimental Example 1

[0122] A composite membrane material, comprising the following preparation method:

[0123] A silicon wafer (pink) is used as a substrate. Ethanol is sprayed evenly onto the substrate to make the substrate surface hydrophilic, thus obtaining a hydrophilic layer. Then, a 4wt% gelatin solution is sprayed evenly onto the material surface. The gelatin solution is prepared by dissolving gelatin in a mixed solution of water and ethanol (the volume ratio of water to ethanol is 1:3). After drying, a gelatin layer is formed, thus obtaining the composite membrane material of this example.

[0124] Experimental Example 2

[0125] A composite membrane material differs from Example 1 in that, in this example, a 2wt% aqueous solution of polyacrylic acid is uniformly sprayed onto the substrate to obtain a hydrophilic layer, while the other raw materials and preparation methods are the same as in Example 1.

[0126] Comparative Example 1

[0127] A composite membrane material, comprising the following preparation method:

[0128] A silicon wafer (pink) is used as a substrate. Ethanol is sprayed unevenly, that is, ethanol is sprayed on part of the surface of the substrate while ethanol is not sprayed on another part of the surface, resulting in a hydrophilic layer on part of the surface of the substrate. Then, a 4wt% gelatin solution is uniformly sprayed on the surface of the material. The gelatin solution is prepared by dissolving gelatin in a mixed solution of water and ethanol (the volume ratio of water to ethanol is 1:3), thus obtaining the composite membrane material of this example.

[0129] The composite film materials of Experimental Examples 1-2 and Experimental Comparative Example 1 were observed under an optical microscope. Since the gelatin material is pale yellow, it is difficult to observe under an optical microscope if it forms a uniform film. Therefore, two marks were made in the composite film material of Experimental Example 1 to facilitate observation. Figure 1 The image shows an optical microscope image of the composite film material from Experiment 1. Only two artificially drawn marks are visible; the thickness and color of the remaining areas are uniform, exhibiting the pinkish hue of the substrate. This demonstrates that using ethanol for uniform coating in Experiment 1 facilitates the even distribution of gelatin on the substrate, resulting in a composite film material with uniform thickness and color. Experiment 2 yields similar results to Experiment 1, using a polyacrylic acid aqueous solution for uniform coating on the substrate, which also contributes to obtaining a uniform composite film material.

[0130] Figure 2 The image shows an optical microscope image of the composite film material in Comparative Example 1. The image reveals uneven pink, green, and yellow areas. The pink area represents the substrate surface coated with ethanol, resulting in a uniformly formed gelatin layer, hence the pink color. The green and yellow areas represent the substrate surface without ethanol coating, where uneven gelatin aggregation occurs. The green area shows slight gelatin aggregation, while the yellow area shows severe aggregation. This demonstrates the importance of the ethanol layer on the substrate surface for the uniform formation of the gelatin layer. Without the ethanol layer, the gelatin solution easily becomes unevenly distributed, leading to aggregation and making it difficult to form a composite film material with uniform properties.

[0131] Figure 3 The image shows a cross-sectional SEM image of the gelatin layer in Example 1. It can be seen that the gelatin layer prepared by the method in Example 1 is thin and uniform in thickness, with a thickness of approximately 100 nm.

[0132] Experimental Example 3

[0133] To test the effects of carbonization treatment and carbonization temperature on the adsorption performance of carbonized ZIF-8 materials, ZIF-8 materials were carbonized at different carbonization temperatures (650℃, 800℃, and 950℃). The specific steps are as follows: ZIF-8 powder was ground and placed in a ceramic crucible, and carbonization was carried out under an Ar / N2 atmosphere. The tube furnace heating process was as follows: heating was carried out at a heating rate of 5℃ / min to 650℃, 800℃, or 950℃, held for 2 hours, and then cooled with the furnace temperature to obtain carbonized ZIF-8 materials, denoted as CZIF-650, CZIF-800, and CZIF-950, respectively. The room temperature krypton and xenon adsorption performance of CZIF-650, CZIF-800, CZIF-950, and uncarbonized ZIF-8 were tested, and the results are as follows. Figure 4 and Figure 5 As shown.

[0134] Figure 4 The adsorption performance curves of CZIF-650, CZIF-800, CZIF-950, and uncarbonized ZIF-8 for krypton are shown. Figure 5 The adsorption performance curves for xenon by CZIF-650, CZIF-800, CZIF-950, and uncarbonized ZIF-8 are shown. It can be seen that, compared to the uncarbonized ZIF-8 material, the carbonized ZIF-8 material exhibits higher adsorption capacity and better adsorption performance for both krypton and xenon. Furthermore, within the carbonization temperature range of this invention, the adsorption performance of the carbonized ZIF-8 material for krypton and xenon is directly proportional to the carbonization temperature, with the carbonized ZIF-8 material (CZIF-950) showing the best performance at a carbonization temperature of 950℃.

[0135] Test Example 4

[0136] To test the effect of gelatin on the adsorption performance of ZIF-8 carbonized material, ZIF-8 carbonized material (CZIF-950) was mixed with gelatin at a mass ratio of 3:2, and the adsorption performance of krypton and xenon at room temperature was tested. The results were compared with the same mass of ZIF-8 carbonized material not mixed with gelatin. The results are as follows: Figure 6 As shown.

[0137] Figure 6 The graph shows the adsorption performance of ZIF-8 carbonized gas before and after mixing with gelatin for krypton and xenon. Kr-gelatin represents the adsorption performance of the mixture of ZIF-8 carbonized gas and gelatin for krypton, Xe-gelatin represents the adsorption performance of the mixture for xenon, Kr represents the adsorption performance of ZIF-8 carbonized gas alone for krypton, and Xe represents the adsorption performance of ZIF-8 carbonized gas alone for xenon. Figure 6It is evident that, compared to ZIF-8 carbon material alone, the composite material obtained by mixing ZIF-8 carbon material with gelatin still exhibits good krypton-xenon adsorption performance, indicating that the good air permeability of gelatin and its coating on the surface of ZIF-8 carbon material have little impact on the adsorption performance of the resulting composite material.

[0138] Example 1

[0139] A metal-organic framework composite membrane includes a substrate, a hydrophilic layer, an adsorption layer, and a fixation layer stacked sequentially; the substrate material is PET, the hydrophilic layer is an ethanol layer, the adsorption layer is a carbonized ZIF-8 layer, and the fixation layer is a gelatin layer; the fixation layer covers the surface of the adsorption layer and is connected to the hydrophilic layer.

[0140] In this example, the metal-organic framework composite film was prepared using a manual coating method, and the preparation flowchart is shown below. Figure 7 As shown, the specific steps include:

[0141] 1) Preparation of ZIF-8 carbonized material: ZIF-8 powder was ground and placed in a ceramic crucible for carbonization under an Ar / N2 atmosphere. The tube furnace heating process was as follows: heating to 950℃ at a heating rate of 5℃ / min, holding at that temperature for 2 hours, and then cooling with the furnace temperature to obtain the ZIF-8 carbonized material. To prevent the ZIF-8 carbonized material from agglomerating and affecting the dispersion of subsequent materials in ethanol / methanol solutions, the ZIF-8 carbonized material was ground using a ball mill or mortar and pestle for 30 minutes.

[0142] 2) Preparation of hydrophilic layer: Take the substrate, spray ethanol evenly on the substrate, and dry the substrate at 80°C to obtain the hydrophilic layer, so as to improve the hydrophilicity of the substrate surface and increase the adhesion.

[0143] 3) Preparation of the ZIF-8 carbonized material layer: 400 mg of ground ZIF-8 carbonized material was dispersed in 10 mL of ethanol solution and pre-treated with ultrasonic stirring for 2 h. The supernatant solution was collected to obtain a ZIF-8 carbonized material dispersion with a concentration of 40 mg / mL. Using a model air pump airbrush painting instrument from Ningbo Haosheng Pneumatic Machinery Co., Ltd., the ZIF-8 carbonized material dispersion was placed in the airbrush painting instrument and manually coated onto the substrate material. The substrate was then dried at 80°C.

[0144] 4) Spraying the fixing layer: Dissolve gelatin in a mixed solution of water and ethanol, with a volume ratio of water to ethanol of 1:3, to obtain a 2wt% gelatin solution. Spray the above gelatin solution onto the dried carbonized ZIF-8 material layer according to the spraying method in 3). After drying, the gelatin fixing layer covers the surface of the carbonized ZIF-8 material layer and contacts the hydrophilic layer, thus obtaining the metal-organic framework composite film.

[0145] Example 2

[0146] A metal-organic framework composite membrane includes a substrate, a hydrophilic layer, an adsorption layer, and a fixation layer stacked sequentially; the substrate material is PET, the hydrophilic layer is a polyacrylic acid layer, the adsorption layer is a carbonized ZIF-8 layer, and the fixation layer is a gelatin layer; the fixation layer covers the surface of the adsorption layer and is connected to the hydrophilic layer.

[0147] In this example, the metal-organic framework composite film was prepared by electrostatic spraying, specifically including the following steps:

[0148] 1) Preparation of ZIF-8 carbonized material: ZIF-8 powder was ground and placed in a ceramic crucible for carbonization under an Ar / N2 atmosphere. The tube furnace heating process was as follows: heating to 950℃ at a heating rate of 5℃ / min, holding at that temperature for 2 hours, and then cooling with the furnace temperature to obtain the ZIF-8 carbonized material. To prevent the ZIF-8 carbonized material from agglomerating and affecting the dispersion of subsequent materials in ethanol / methanol solutions, the ZIF-8 carbonized material was ground using a ball mill or mortar and pestle for 30 minutes.

[0149] 2) Preparation of hydrophilic layer: Take the substrate and spray a 2wt% polyacrylic acid aqueous solution evenly on the substrate to obtain a hydrophilic layer, which improves the hydrophilicity of the substrate surface and increases adhesion.

[0150] 3) Preparation of the ZIF-8 carbonized material layer: 400 mg of ground ZIF-8 carbonized material was dispersed in 10 mL of ethanol solution and pre-ultrasonicated for 2 h. The supernatant solution was collected to obtain a ZIF-8 carbonized material dispersion with a concentration of 40 mg / mL. Using an electrostatic spraying machine, the substrate material with the prepared hydrophilic layer was placed on the rollers of the electrostatic spraying machine. The ZIF-8 carbonized material dispersion was uniformly sprayed onto the hydrophilic layer using electrostatic spraying for 1 h. The voltage, nozzle movement speed, roller speed, and injection speed were all set at 7 kV, 30 mm / min, 50 rpm, and 6 mL / h, respectively. The substrate was dried at 80℃.

[0151] 4) Spraying the fixing layer: Dissolve gelatin in a mixed solution of water and ethanol, with a volume ratio of water to ethanol of 1:3, to obtain a 3wt% gelatin solution. Apply the gelatin solution to the dried carbonized ZIF-8 material layer using the electrostatic spraying method and conditions described in 3), with a spraying time of 15 minutes. After drying, the gelatin fixing layer coats the surface of the carbonized ZIF-8 material layer and contacts the hydrophilic layer, thus obtaining the metal-organic framework composite film. The composite film obtained in this example is designated CZIF-950-1x.

[0152] Example 3

[0153] A metal-organic framework composite membrane differs from Example 2 in that, in this example, step 3) is repeated, and the ZIF-8 carbonized material dispersion is sprayed five times. The other raw materials and preparation methods are the same as in Example 2. The composite membrane obtained in this example is designated CZIF-950-5x.

[0154] Comparative Example 1

[0155] A metal-organic framework composite membrane differs from Example 2 in that it does not have a fixing layer, while the other raw materials and preparation methods are the same as in Example 2.

[0156] Figure 8 The images shown are SEM images of the metal-organic framework composite film of Example 2, where (A) and (B) are planar SEM images at different magnifications, and (C) is a cross-sectional SEM image. Figure 9 The images shown are SEM images of the metal-organic framework composite film of Example 3, where (A) and (B) are planar SEM images at different magnifications, and (C) is a cross-sectional SEM image. Figures 8-9 It is evident that metal-organic framework composite membranes possess abundant pore structures and exhibit excellent compactness. Furthermore, compared to… Figures 8-9 It is evident that CZIF-950-5x has a thicker film thickness than CZIF-950-1x. By repeating step 3) of spraying the carbonized ZIF-8 material dispersion, composite film materials of different thicknesses can be obtained, thus achieving controllable film thickness. The film thickness can be adjusted according to actual needs, and the adjustment method is simple and easy to implement. Since the adsorption layer is the main component of the composite film material for adsorption, a thicker adsorption layer is beneficial for obtaining materials with better adsorption performance.

[0157] Figure 10 The adsorption performance curves of krypton on the metal-organic framework composite membranes and PET substrates of Examples 2 and 3 are shown. Figure 11 The figures show the adsorption performance curves of xenon on the metal-organic framework composite membrane and the PET substrate material in Examples 2 and 3. It can be seen that setting an adsorption layer on the PET substrate material can improve the adsorption performance of the material for krypton and xenon. Furthermore, by adjusting the thickness of the adsorption layer, the adsorption performance of the composite membrane for krypton and xenon can be effectively improved.

[0158] In terms of mechanical properties and stability, Comparative Example 1 did not fix the ZIF-8 material, and the carbonized ZIF-8 material was very easy to fall off, resulting in poor mechanical properties and stability, short service life, and seriously affecting its industrial application. In contrast, Examples 1-3 used a combination of gelatin layer and hydrophilic layer to fix the carbonized ZIF-8 material, resulting in composite films with good mechanical properties, high adhesion, strong stability, long service life, and good adsorption performance, showing good application prospects in industry.

[0159] As can be seen from the above experimental examples, embodiments, and comparative examples, the metal-organic framework composite membrane obtained by the method of the present invention has high density, good mechanical properties, and high adhesion. The membrane structure is uniform, thin, and its thickness is controllable. Importantly, it exhibits excellent gas adsorption performance, especially high adsorption capacity for Kr and Xe, making it widely applicable in the adsorption and enrichment of krypton and / or xenon. The substrate material of the present invention can be flexibly selected according to actual industrial application scenarios, and the membrane size can be cut according to actual needs, with controllable area. Furthermore, the thickness can be adjusted by regulating the thickness of the adsorption layer. The composite membrane of the present invention is suitable for various industrial production needs, has low equipment requirements, and a simple and easy-to-implement preparation process.

[0160] In the metal-organic framework composite membrane of this invention, the adsorption layer contains carbonized MOFs material. Compared with uncarbonized MOFs material, the carbonized MOFs material has a specific pore structure and pore size, exhibiting good adsorption properties for krypton and / or xenon. Therefore, the metal-organic framework composite membrane of this invention can be used for the adsorption and enrichment of krypton and / or xenon. Based on the good adsorption capacity of the composite membrane material for Kr and Xe in this invention, using the composite membrane material as an adsorbent can remove krypton and / or xenon from the mixed gas, achieving effective adsorption and enrichment of krypton and / or xenon in the mixed gas.

[0161] In summary, this invention uses a metal-organic framework (MOF) material as the adsorption layer. This material has abundant mesoporous structure and high specific surface area, which is beneficial for improving the adsorption activity of the composite membrane. Furthermore, through the combination of the hydrophilic layer and the immobilization layer, the adsorption layer can be firmly fixed in the membrane material using the good adhesion between them, forming a MOF composite membrane with good adsorption performance, high mechanical properties, good stability, and high density. Moreover, the preparation process is simple and requires minimal equipment. The composite membrane of this invention has good application prospects in gas adsorption and enrichment, especially in the adsorption and enrichment of krypton and / or xenon.

Claims

1. A metal-organic framework composite membrane, characterized in that, The device comprises a substrate, a hydrophilic layer, an adsorption layer, and a fixation layer arranged sequentially. The fixation layer covers the surface of the adsorption layer and is connected to the hydrophilic layer. The adsorption layer contains a metal-organic framework material, and the fixation layer contains a hydrophilic polymer. The hydrophilic polymer includes at least one of gelatin, hyaluronic acid gelatin, chitosan, hyaluronic acid, polyethylene glycol, polyacrylic acid and its derivatives, polyvinyl alcohol, polyoxyethylene, polyacrylamide, polyhydroxyethyl methacrylate, polyacrylic acid, or polymethacrylic acid.

2. The metal-organic framework composite membrane according to claim 1, wherein the raw materials for preparing the hydrophilic layer include at least one selected from polyacrylic acid, methanol, ethanol, or propanol; And / or, the substrate material includes at least one of polyethylene terephthalate, silicon substrate, aluminum foil, or plastic substrate.

3. The metal-organic framework composite membrane according to claim 1, characterized in that, The mass ratio of the metal-organic framework material to the hydrophilic polymer is 1:(0.1~1.2).

4. The metal-organic framework composite membrane according to any one of claims 1 to 3, characterized in that, The thickness of the hydrophilic layer is 10~50nm; And / or, the thickness of the adsorption layer is ≥30nm; And / or, the thickness of the fixing layer is 30~200nm.

5. A method for preparing a metal-organic framework composite membrane, characterized in that, Includes the following steps: S1. Take a substrate and apply the raw materials for preparing the hydrophilic layer to the surface of the substrate to form a hydrophilic layer; S2. Apply a first dispersion containing a metal-organic framework material to the hydrophilic layer, and then dry it to form an adsorption layer; S3. Apply a second dispersion containing a hydrophilic polymer to the adsorption layer, then dry it to form a fixed layer, and obtain the metal-organic framework composite film; The composition of the metal-organic framework composite membrane is as described in any one of claims 1 to 4.

6. The preparation method according to claim 5, characterized in that, The solvent in the first dispersion is a first solvent, which includes volatile alcohol solvents; And / or, the concentration of the carbide metal-organic framework material in the first dispersion is 20~100 mg / mL; And / or, the solvent in the second dispersion is a second solvent, which includes water, volatile alcohol solvents, or combinations thereof; And / or, the concentration of the hydrophilic polymer in the second dispersion is 1~8wt%.

7. The preparation method according to claim 5, characterized in that, In step S2, the carbonized metal-organic framework material is obtained by carbonizing metal-organic framework material.

8. The preparation method according to claim 7, characterized in that, The carbonization treatment temperature is 500~1200℃; And / or, the heating rate of the carbonization treatment is 1~10℃ / min; And / or, the carbonization treatment time is 0.5~5h.

9. The preparation method according to claim 5, characterized in that, In step S2, the first dispersion is applied and then dried 1 to 10 times. And / or, in steps S2 to S3, the drying temperature is independently 40 to 100°C; And / or, in steps S1 to S3, the application method is independently selected from manual coating, electrostatic spraying, or a combination thereof.

10. The application of a metal-organic framework composite membrane as described in any one of claims 1 to 4, or a metal-organic framework composite membrane prepared by the preparation method described in any one of claims 5 to 9, in gas adsorption and enrichment.

11. The application according to claim 10, characterized in that, The gas includes an inert gas.

12. A method for adsorption and enrichment of krypton and / or xenon, characterized in that, Using the metal-organic framework composite membrane according to any one of claims 1 to 4, or the metal-organic framework composite membrane prepared by the preparation method according to any one of claims 5 to 9, as an adsorbent, a mixed gas containing krypton and / or xenon is adsorbed to achieve the enrichment of krypton and / or xenon.

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