An anion-supported ultraporous membrane, its preparation method and application

Abstract

This invention discloses an anion-pillared ultraporous membrane, its preparation method, and its application in the separation of low-carbon hydrocarbons. The ultraporous membrane exhibits stable properties and excellent separation selectivity and permeation flux. Preparation method: A polymer with hydrogen-bonded groups is spin-coated onto a substrate, dried to form a film, the substrate is modified, and then an inorganic anion-pillared ultraporous material layer is grown in situ on the substrate surface to obtain the ultraporous membrane. The inorganic anion-pillared ultraporous material layer is formed by the self-assembly of metal ions, inorganic anions, and flexible ligands through coordination bonds; the metal ion is Cu. 2+ Zn 2+ At least one of the following; the inorganic anion is SiF6. 2‑ GeF6 2‑ At least one of the following; the flexible ligand is at least one of 4,4'-bipyridine sulfide and 4,4'-bipyridine sulfoxide.

Description

Technical Field

[0001] This invention relates to the fields of membrane separation and low-carbon hydrocarbon separation, specifically to an anion-supported ultraporous membrane, its preparation method, and its application in low-carbon hydrocarbon separation. Background Technology

[0002] Selective separation of structurally similar compounds and deep removal of trace components are crucial in the manufacture of high-purity chemicals and represent one of the technological challenges in the field of chemical separation. Traditional separation methods, such as solvent extraction and cryogenic distillation, suffer from drawbacks such as high energy consumption and high material consumption.

[0003] With the development of porous materials such as molecular sieves, porous coordination polymers (PCPs), and metal-organic frameworks (MOFs), adsorption separation technology has gained widespread attention in recent years. For example, patent CN 110193352 A discloses a functionalized cage-like borane anion-supported supramolecular microporous framework material, composed of metallic Cu. 2+ The ion coordinates with the organic nitrogen-containing ligand L to form a two-dimensional planar structure, and then reacts with the iodine-substituted functionalized cage-like dodecorane anion [B]. 12 H 11 I] 2- The bridging forms a three-dimensional layered columnar framework structure. This invention can be used for the selective purification of methane, specifically exhibiting highly selective adsorption separation of propylene / methane, propane / methane, ethane / methane, ethylene / methane, and acetylene / methane, yielding high-purity methane gas and recovering C2-C3 low-carbon hydrocarbons. It can be applied to the selective adsorption separation of industrial mixed gases containing large amounts of methane, such as natural gas, biogas, and cracked gas.

[0004] Adsorption separation technology does not involve phase change or high temperature, and has low energy consumption, making it a highly efficient separation method. However, adsorption separation technology still has drawbacks such as low adsorbent capacity and frequent adsorption-desorption operations. Therefore, there is an urgent need to develop efficient and energy-saving low-carbon hydrocarbon gas separation technologies.

[0005] Membrane separation technology, as a low-energy and environmentally friendly separation technology, is a potential approach to achieve efficient separation of low-carbon hydrocarbon molecules. However, gas separation membrane materials generally suffer from the technical bottleneck of not being able to simultaneously improve separation selectivity and permeation flux.

[0006] The key to improving the separation selectivity of membrane materials lies in the construction of molecular-scale pores within the membrane, and one practical way to increase the permeate flux of separation membranes is to effectively reduce the membrane thickness. The challenge in constructing porous membrane materials with high selectivity and high permeate flux lies in the need for precise control over both the pore structure and the membrane material structure.

[0007] Two-dimensional layered anion-hybrid ultraporous materials utilize ligands and metal nodes to form ultraporous channels and windows, while the metal nodes coordinate with anions to form a two-dimensional layered framework structure. These materials possess tunable pore microenvironments and unique two-dimensional structures, suggesting that they may be able to be structurally controlled and exfoliated into nanosheets for highly selective and rapid transport of low-carbon hydrocarbon molecules.

[0008] Therefore, this application proposes to construct layered anion-pillared ultraporous membranes using two-dimensional layered anion hybrid ultraporous materials. The layered anion-pillared ultraporous membranes designed and constructed based on two-dimensional layered anion hybrid ultraporous materials have the following advantages:

[0009] 1) The anion-functionalized micropores within two-dimensional layered anion-hybridized microporous materials can achieve specific recognition of low-carbon hydrocarbon molecules, enabling selective separation of gas molecules.

[0010] 2) The channels within the two-dimensional layered anion-containing ultraporous materials and between the nanosheets provide more mass transfer channels for gas molecules. This holds promise for overcoming the trade-off between membrane material separation selectivity and permeation flux, enabling the application of this type of membrane material in the separation of low-carbon hydrocarbons. Summary of the Invention

[0011] To address the technical problems existing in this field, the present invention provides an anion-pillared ultraporous membrane, its preparation method, and its application in the separation of low-carbon hydrocarbons. This anion-pillared ultraporous membrane is obtained by in-situ growth of an inorganic anion-pillared ultraporous material layer on the surface of a modified substrate. The preparation method provided by the present invention is reliable, simple, and easy to operate. The prepared anion-pillared ultraporous membrane exhibits stable properties and excellent separation selectivity and permeation flux.

[0012] This invention is achieved through the following technical solution:

[0013] A method for preparing anion-supported ultraporous membrane includes the following steps:

[0014] (1) A polymer with hydrogen-bonded groups is spin-coated onto a substrate layer and dried to form a film, thereby obtaining a modified substrate layer;

[0015] (2) An inorganic anion-pillared ultraporous material layer is grown in situ on the surface of the modified substrate obtained in step (1) to obtain the anion-pillared ultraporous membrane.

[0016] The polymer having hydrogen-bonded groups is at least one of polyvinyl alcohol (PVA) and polyethylene glycol (PEG);

[0017] The substrate layer comprises an inorganic substrate layer and an organic polymer substrate layer. The inorganic substrate layer is made of alumina (Al2O3), and the organic polymer substrate layer is made of one of the following: polyethersulfone (PES), polyethersulfone / polyvinylpyrrolidone (PES / PVP) resin, and polyethersulfone / sulfonated polyetheretherketone (PES / SPEEK) resin.

[0018] The inorganic anion-supported ultraporous material layer is formed by the self-assembly of metal ions, inorganic anions, and flexible ligands through coordination bonds; the metal ions are Cu. 2+ Zn 2+ At least one of the following; the inorganic anion is SiF6. 2- GeF6 2- At least one of the following; the flexible ligand is at least one of 4,4'-bipyridine sulfide (dps) and 4,4'-bipyridine sulfoxide sulfoxide.

[0019] The preparation method provided by the present invention first modifies the substrate with a polymer rich in hydrogen bonds, that is, the surface of the substrate layer is enriched with functional groups with strong hydrogen bonds by spin coating and drying, so as to induce the oriented growth of the subsequent anion-pillared ultraporous material layer. Then, the two-dimensional layered anion-pillared ultraporous membrane is obtained by solvothermal reaction in situ growth on the substrate surface.

[0020] The preparation method provided by this invention achieves the construction of ultra-micro channels through functionalized anion pillars and flexible ligands, thereby improving the separation selectivity of membrane materials. At the same time, the channels within the two-dimensional layered anion ultra-microporous material and between the nanosheets provide more mass transfer channels for gas molecules, thereby increasing the permeation flux of the membrane material.

[0021] Preferably, the substrate layer is made of inorganic alumina (Al2O3) substrate.

[0022] Preferably, the metal ion is Cu. 2+ The inorganic anion is GeF6. 2- The flexible ligand is 4,4'-bipyridine sulfide, which is used to construct a layered anion-supported ultraporous material.

[0023] Preferably, in step (1), the concentration of the polymer having hydrogen-bonded groups in the spin coating solution is 5-10%.

[0024] Preferably, in step (1), the drying temperature is 80-100℃ and the time is 2-12h to ensure that the material is fully dried.

[0025] Preferably, in step (2), the in-situ growth is carried out by a solvothermal reaction. More preferably, in step (2), the modified substrate obtained in step (1) is first immersed in a mixed solution of inorganic anionic salt solution and metal salt solution to fully wet the surface of the substrate, and then a flexible ligand solution is added to carry out the solvothermal reaction to ensure the formation of a uniform and dense anionic pillar layer on the substrate surface.

[0026] More preferably, the inorganic anionic salt is (NH4)2GeF6, and the metal salt solution is a 45% Cu(BF4)2 aqueous solution.

[0027] More preferably, the soaking time is not less than 4 hours to ensure that the metal ions are fully wetted by the substrate, providing contact sites for subsequent in-situ growth.

[0028] More preferably, the flexible ligand solution is slowly added dropwise to the mixed solution soaked with the base film layer under stirring conditions, at a rate of 50-70 drops / min, and stirred for 1-2 hours. The slow addition helps to ensure the uniformity of the reaction.

[0029] More preferably, the solvothermal reaction is carried out at a temperature of 25-80°C for 12-72 hours. More preferably, the solvothermal reaction is carried out at a temperature of 25°C for 12-24 hours to ensure that the reaction proceeds fully.

[0030] More preferably, the solvent for the solvothermal reaction is one of methanol, ethanol, and isopropanol. More preferably, the solvent for the solvothermal reaction is methanol, as methanol has the best solubility for ligands and metal salts.

[0031] This invention also provides an anion-pillared ultraporous membrane. Using this anion-pillared ultraporous membrane as a gas separation membrane material, it can simultaneously possess excellent gas separation selectivity and high permeation flux, solving the common problem in gas separation membrane materials where it is difficult to simultaneously achieve both permeation flux and selectivity.

[0032] An anion-supported ultraporous membrane is prepared according to the preparation method provided by the present invention.

[0033] The anion-pillared ultraporous membrane provided by the present invention includes a substrate layer and a selective inorganic anion-pillared ultraporous material layer grown in situ on the substrate layer. The inorganic anion-pillared ultraporous material layer is regularly arranged in a certain direction and forms a two-dimensional layered structure.

[0034] Preferably, the inorganic anion-supported ultraporous material layer has a thickness of 0.2-5 μm, a porosity of 70-90%, and a specific surface area of ​​100-500 m². 2 / g, ensuring a certain permeation flux and selectivity.

[0035] Preferably, the thickness of the anion-pillared ultraporous membrane is 100-1000 μm, the pore size is 0.3-70 nm, and the porosity is 60-90%. In the anion-pillared ultraporous membrane, the compactness of the substrate layer affects the overall separation performance of the anion-pillared ultraporous membrane.

[0036] This invention also provides an application of the described anion-pillared ultraporous membrane in the separation of low-carbon hydrocarbons. By designing the pore structure and pore environment of the described anion-pillared ultraporous membrane, it can be applied to different gas separation systems.

[0037] An application of the aforementioned anion-supported ultraporous membrane in the separation of low-carbon hydrocarbons, wherein the low-carbon hydrocarbons are those with 5 or fewer carbon atoms. The anion-supported ultraporous membrane is used as the separation membrane and assembled into a gas separation device for gas separation.

[0038] The gas separation system can be a low-carbon olefin / alkyne or a low-carbon olefin / alkane.

[0039] Preferably, the gas separation system is selected from one of acetylene / ethylene, propyne / propylene, ethylene / ethane, propylene / propane, and acetylene / carbon dioxide, and the anion-supported layer has a specific interaction with the gas.

[0040] Compared with the prior art, the present invention has at least the following significant technical effects:

[0041] 1) In the anion-supported ultraporous membrane provided in this application, the anion-functionalized ultraporous channels in the membrane material can achieve specific recognition of low-carbon hydrocarbon molecules. At the same time, the two-dimensional membrane material structure provides more mass transfer channels for gas molecules, thereby achieving simultaneous improvement in membrane material separation selectivity and permeation flux.

[0042] 2) This application addresses the demand for high-performance separation membrane materials in the development of low-carbon hydrocarbon separation technology. It designs and constructs anion-supported ultraporous membranes with excellent gas separation performance and realizes the first application of this type of membrane material in the field of low-carbon hydrocarbon separation, providing support for the development of low-carbon hydrocarbon separation technology.

[0043] 3) This application will promote the application of two-dimensional anion-pillared ultraporous materials in the field of membrane separation. Anion-pillared porous materials are a new type of material with many advantages and have extremely important applications in adsorption separation, gas storage, and other fields. However, current research on this type of material mainly focuses on adsorbents, and there are few reports on the molding of adsorbents and the design and preparation of separation membranes based on anion-pillared porous materials. This application aims to prepare this type of material into a high-performance separation membrane material, thus expanding its application in the field of membrane separation.

[0044] 4) This application utilizes a polymer with hydrogen-bonded groups to modify the substrate layer, enabling the in-situ growth of a two-dimensional anion-supported microporous material layer with a specific orientation on the substrate layer. The process is simple and easy to operate, and the resulting membrane material has good stability and excellent performance. Attached Figure Description

[0045] Figure 1 The images show the surface morphology of the anion-pillared ultraporous membrane prepared in Example 1, where a is the surface morphology of the Al2O3 substrate layer and b is the surface morphology of the Cu(dps)2(GeF6) anion-pillared ultraporous membrane.

[0046] Figure 2 The diagram shows the gas separation performance of the Cu(dps)2(GeF6) anion-pillared ultraporous membrane prepared in Example 1, where a is the separation selectivity of the anion-pillared ultraporous membrane for acetylene / carbon dioxide and acetylene / ethylene, and b is the stability performance of the anion-pillared ultraporous membrane.

[0047] Figure 3 The image shows the morphology of the polymer PES-SPEEK substrate prepared in Example 2, where a is the surface morphology, b is the cross-sectional morphology, and c is the surface morphology of the Cu(dps)2(GeF6) anion-supported ultraporous membrane prepared on the PES-SPEEK substrate.

[0048] Figure 4 The diagram shows the gas separation performance of the Cu(dps)2(GeF6) anion-pillared ultraporous membrane prepared in Example 2, where a is the separation selectivity performance of the anion-pillared ultraporous membrane for acetylene / carbon dioxide and acetylene / ethylene, and b is the stability performance of the membrane material.

[0049] Figure 5 The graph shows the gas separation performance of the Cu(dps)2(SiF6) anion-supported ultraporous membrane prepared in Example 4.

[0050] Figure 6 The image shows the gas separation performance of the irregularly oriented Cu(dps)2(GeF6) anion-supported ultraporous membrane prepared for Comparative Example 1. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0052] Example 1

[0053] First, a 5% polyvinyl alcohol (PVA) aqueous solution was prepared. 5 ml of the above PVA solution was taken and spin-coated onto the surface of a commercial Al2O3 inorganic substrate (Φ13×1mm) to form a PVA modification layer. Then, the substrate was vacuum dried at 100°C for 2 hours to form a film.

[0054] Furthermore, 4,4'-bipyridine sulfide (CAS: 37968-97-1) was used, with Cu as the metal node and GeF6... 2- Cu(dps)2(GeF6) anion hybrid ultraporous membrane material was synthesized via a solvothermal method using methanol as a solvent and hybrid anion as the solvent.

[0055] Specifically, 0.26 mmol of Cu(BF4)2 aqueous solution and 0.26 mmol of (NH4)2GeF6 were dissolved in 5 ml of methanol. The PVA-modified Al2O3 inorganic substrate was then immersed in this solution for 6 hours, allowing the metal ions and inorganic anions to fully wet the substrate surface. Further, 0.52 mmol of 4,4'-bipyridine sulfide was dissolved in 5 ml of methanol and slowly added to the salt solution impregnated with the substrate, resulting in the formation of a pale purple precipitate. Under the influence of the PVA layer, the abundant hydroxyl groups on the PVA surface induced the uniform nucleation of two-dimensional Cu(dps)2(GeF6) grains along a direction parallel to the substrate. By controlling the reaction temperature at 25 °C and the reaction time at 24 hours, the Cu(dps)2(GeF6) material further oriented and grew on the substrate surface, forming a two-dimensional Cu(dps)2(GeF6) anion-hybridized ultraporous material. Figure 1 After the reaction is complete, remove the sample, wash it 3-4 times with methanol, and dry it at 40°C until completely dry for testing.

[0056] A two-dimensional Cu(dps)₂(GeF₆) anion-supported ultraporous membrane was prepared and assembled into a gas separation membrane device using a sandwich structure (gasket-membrane-gasket). A constant pressure of 0.5 MPa gas flow was passed upstream. The time required for the flow to pass through the fixed flow rate was recorded by a flow meter at the outlet. The flux of different gas molecules through the membrane was calculated, and the separation selectivity was then determined. The permeation flux of acetylene, ethylene, and carbon dioxide gas molecules through the prepared Cu(dps)₂(GeF₆) anion-supported ultraporous membrane and the selectivity of acetylene / carbon dioxide and acetylene / ethylene were measured respectively. The results are as follows: Figure 2 As shown, Figure 2 a shows that the membrane material exhibits specific acetylene adsorption, demonstrating high acetylene / ethylene selectivity. Figure 2 b shows that the membrane material's permeation flux for acetylene remained stable during a long-cycle performance test lasting nearly 8 hours.

[0057] Example 2

[0058] Polyethersulfone (PES) and sulfonated polyetheretherketone (SPEEK) were dissolved in N,N-dimethylacetamide (DMAC) solvent at a mass ratio of 9:1 to obtain a blend solution with a solid content of 35 wt%. After stirring evenly and allowing it to stand, the solution was poured onto a clean and flat glass plate. Under 20% humidity, a flat diaphragm was scraped out using a 200 μm scraper, immersed in water, and allowed to dissolve. After removing the solvent, a PES / SPEEK porous organic substrate was obtained. Figure 3 a, b) The membrane exhibits a finger-like macroporous morphology, with a thickness of 105 μm, a pore size of 0.3-100 nm, and a porosity of 60-80%.

[0059] First, prepare a 5% polyvinyl alcohol (PVA) aqueous solution. Take 5 ml of the above PVA solution and spin-coat it onto the prepared PES / SPEEK porous organic substrate to form a PVA modification layer on the surface. Then, vacuum dry at 100°C for 2 hours to form a film.

[0060] The preparation method of in-situ growth of two-dimensional Cu(dps)₂(GeF₆) anion-hybridized ultraporous materials on porous substrates via solvothermal synthesis is basically the same as in Example 1. The final result is a two-dimensional Cu(dps)₂(GeF₆) anion-pillared ultraporous membrane with a polymer substrate. Figure 3 c).

[0061] A two-dimensional Cu(dps)₂(GeF₆) anion-supported ultraporous membrane was prepared and assembled into a gas separation membrane device. The permeation flux of acetylene, ethylene, carbon dioxide, propyne, and propylene gas molecules through the prepared two-dimensional Cu(dps)₂(GeF₆) anion-supported ultraporous membrane and the selectivity of acetylene / carbon dioxide and acetylene / ethylene were measured. The results are as follows: Figure 4 As shown, the separation selectivity of the membrane material is close to that of the membrane material in Example 1 with an inorganic membrane substrate. However, the overall acetylene gas flux is lower than that of the membrane material in Example 1. This is mainly because the dense structure of the polymer substrate (thickness of 105 μm, pore size of 0.3-100 nm, and porosity of 60-80%) reduces the overall permeation flux of the membrane material.

[0062] Example 3

[0063] Polyethersulfone (PES) was dissolved in N,N-dimethylacetamide (DMAC) solvent to obtain a blend solution with a solid content of 35 wt%. After stirring and standing, the solution was poured onto a clean and flat glass plate. Under 20% humidity, a flat membrane was scraped out with a 200 μm doctor blade and immersed in water. After the solvent was dissolved and removed, a porous PES organic substrate was obtained. The membrane had dense micropores, a thickness of 105 μm, a pore size of 0.3-100 nm, and a porosity of 50-70%.

[0064] First, a 5% polyvinyl alcohol (PVA) aqueous solution was prepared. 5 ml of the PVA solution was spin-coated onto the surface of the prepared PES porous organic substrate to form a PVA modification layer, followed by vacuum drying at 100°C for 2 hours to form a film. The preparation method for in-situ growth of two-dimensional Cu(dps)₂(GeF₆) anion-hybridized ultraporous materials on the porous substrate surface via solvothermal synthesis was basically the same as in Example 1. Finally, a two-dimensional Cu(dps)₂(GeF₆) anion-pillared ultraporous membrane was prepared using PES as the substrate.

[0065] The two-dimensional Cu(dps)2(GeF6) anion-pillared ultraporous membrane was assembled into a gas separation membrane device, and the selectivity of acetylene / carbon dioxide and acetylene / ethylene was measured. The overall acetylene gas flux of the membrane material was lower than that of the anion-pillared ultraporous membrane prepared with Al2O3 inorganic substrate in Example 1 and PES / SPEEK in Example 2. The main reason is that the dense pore structure of the PES membrane affects the overall permeability of the membrane material, indicating that the choice of substrate layer in the anion-pillared ultraporous membrane has a significant impact on the overall membrane permeability.

[0066] Example 4

[0067] First, a 5% polyvinyl alcohol (PVA) aqueous solution was prepared. 5 ml of this PVA solution was spin-coated onto a commercially available Al₂O₃ inorganic substrate (Φ13×1 mm) to construct a PVA modification layer, which was then vacuum-dried at 100°C for 2 hours to form a film. Further, 4,4'-bipyridine sulfide was used, with Cu as the metal node and SiF₆... 2- Cu(dps)₂(SiF₆) anion-hybridized ultraporous membrane material was synthesized via a solvothermal method using methanol as the solvent and hybrid anion as the solvent. The specific preparation method was the same as in Example 1. After the reaction was completed, the membrane was removed, washed 3-4 times with methanol, and dried completely at 40°C to finally obtain a two-dimensional Cu(dps)₂(SiF₆) anion-pillared ultraporous membrane.

[0068] A two-dimensional Cu(dps)₂(SiF₆) anion-supported ultraporous membrane was prepared and assembled into a gas separation membrane device. The permeation flux of acetylene, ethylene, and carbon dioxide gas molecules through the prepared two-dimensional Cu(dps)₂(SiF₆) anion-supported ultraporous membrane and the selectivity of acetylene / carbon dioxide and acetylene / ethylene were measured, respectively. The results are as follows: Figure 5 As shown, the Cu(dps)2(SiF6) membrane exhibits similar separation performance to the Cu(dps)2(GeF6) membrane, demonstrating specific adsorption of acetylene gas, proving the universality of this type of anion-pillared ultraporous material in the construction of gas separation membrane strategies.

[0069] Example 5

[0070] The method for modifying a commercially available Al2O3 inorganic substrate (Φ13×1mm) with PVA is essentially the same as in Example 1. Further, the metal ions are changed, using 4,4'-bipyridine sulfide, with Zn as the metal node and GeF6... 2- Zn(dps)₂(GeF₆) anion-hybridized ultraporous membrane material was synthesized via a solvothermal method using methanol as the solvent and hybrid anion as the solvent. The specific membrane material preparation process was basically the same as in Example 1. After the reaction was completed, the membrane was removed, washed 3-4 times with methanol, and dried at 40°C to finally obtain a two-dimensional Zn(dps)₂(GeF₆) anion-pillared ultraporous membrane.

[0071] A two-dimensional Zn(dps)₂(GeF₆) anion-supported ultraporous membrane was prepared and assembled into a gas separation membrane device. The membrane separation test procedure was basically the same as in Example 1. The permeation flux of acetylene, ethylene, and carbon dioxide gas molecules through the prepared two-dimensional Zn(dps)₂(GeF₆) anion-supported ultraporous membrane was measured. The Zn(dps)₂(GeF₆) membrane exhibited performance similar to that of the Cu(dps)₂(GeF₆) membrane. The permeation flux for acetylene gas was lower than that in Example 1, demonstrating the tunability of the membrane material structure and performance.

[0072] Comparative Example 1

[0073] Without PVA modification, a commercially available Al₂O₃ inorganic substrate (Φ13×1mm) was directly immersed in 5 ml of methanol containing 0.26 mmol Cu(BF₄)₂·xH₂O and 0.26 mmol (NH₄)₂SiF₆. After immersion for 6 hours, 0.52 mmol 4,4'-bipyridine sulfide was dissolved in 5 ml of methanol and slowly added to the salt solution containing the substrate. A pale purple precipitate was observed to form. Without the PVA layer, Cu(dps)₂(GeF₆) grains randomly nucleated and grew on the substrate surface, forming a Cu(dps)₂(GeF₆) anion-supported ultraporous membrane without specific orientation, as shown in the figure. After the reaction was complete, the substrate was removed, washed 3-4 times with methanol, and dried at 40°C until fully dry for testing.

[0074] The randomly oriented Cu(dps)₂(GeF₆) anion-supported ultraporous membrane was assembled into a gas separation membrane device, and its permeation flux for acetylene, ethylene, and carbon dioxide gas molecules was tested. The results are as follows: Figure 6 As shown, the irregular distribution of the anion-supported ultraporous material leads to poor membrane material selectivity. Comparative Example 1 demonstrates the importance of modifying the substrate layer in the preparation method of this invention.

[0075] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. The application of an anion-supported ultraporous membrane in the separation of acetylene / ethylene or acetylene / carbon dioxide, characterized in that, The preparation method of the anion-supported ultraporous membrane includes the following steps: (1) A polymer with hydrogen-bonded groups is spin-coated onto a substrate layer and dried to form a film, thereby obtaining a modified substrate layer; (2) An inorganic anion-pillared ultraporous material layer is grown in situ on the surface of the modified substrate obtained in step (1) by solvothermal reaction. First, the modified substrate obtained in step (1) is immersed in a mixed solution of inorganic anion salt solution and metal salt solution so that inorganic anions and metal ions fully wet the surface of the substrate. Then, a flexible ligand solution is added to carry out the solvothermal reaction to obtain the anion-pillared ultraporous membrane. The polymer having hydrogen-bonded groups is at least one of polyvinyl alcohol and polyethylene glycol; The substrate layer comprises an inorganic substrate layer and an organic polymer substrate layer. The inorganic substrate layer is made of alumina, and the organic polymer substrate layer is made of a material selected from polyethersulfone, polyethersulfone / polyvinylpyrrolidone resin, and polyethersulfone / sulfonated polyetheretherketone resin. The inorganic anion-pillared ultraporous material layer is formed by the self-assembly of metal ions, inorganic anions, and flexible ligands through coordination bonds; the metal ions are Cu. 2+ The inorganic anion is GeF6. 2- The flexible ligand is 4,4'-bipyridine sulfide.

2. The application according to claim 1, characterized in that, In step (1), the concentration of the polymer with hydrogen-bonded groups in the spin coating solution is 5-10%.

3. The application according to claim 1, characterized in that, In step (1), the drying temperature is 80-100℃ and the time is 2-12h.

4. The application according to claim 1, characterized in that, In step (2): The solvothermal reaction is carried out at a temperature of 25-80℃ for a time of 12-72 hours. The solvent for the solvothermal reaction is one of methanol, ethanol, or isopropanol.

5. The application according to claim 1, characterized in that, The inorganic anion-pillared ultraporous material layer has a thickness of 0.2-5 μm, a porosity of 70-90%, and a specific surface area of ​​100-500 m². 2 / g.

6. The application according to claim 1, characterized in that, The thickness of the anion-supported ultraporous membrane is 100-1000 μm, the pore size is 0.3-70 nm, and the porosity is 60-90%.

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