A MOF-COF hybrid membrane and a preparation method thereof
By preparing MOF-COF hybrid membranes, the problems of framework flexibility deformation and poor stability of existing membrane materials in gas separation are solved, and the selectivity and stability of gas separation are improved, with good continuity and a defect-free dense structure.
Patent Information
- Application Number
- CN202311482650.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-09
- Publication Date
- 2025-11-28
- Estimated Expiration
- 2043-11-09
AI Technical Summary
Existing membrane materials suffer from problems such as framework flexibility deformation, intergranular defects, and poor stability during gas separation, resulting in unsatisfactory separation performance.
MOF-COF hybrid membranes were prepared by ultrasonically dissolving COF nanosheets and metal salts in deionized water and then transferring them onto a support. The support was then immersed in a growth solution to form a MOF-COF hybrid membrane. An activator was used to ensure uniform distribution and good bonding between the two phases.
A MOF-COF hybrid membrane with excellent gas separation selectivity and stability has been achieved. It is simple and economical to operate and has good continuity and a defect-free dense structure.
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Figure CN117654316B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of membrane materials, in particular to a MOF-COF hybrid membrane and a preparation method thereof. BACKGROUND
[0002] Separation process is a very important and indispensable industrial process in chemical industry, traditional separation process includes physical separation (distillation / adsorption) and chemical separation method, i.e. absorption method, which has high energy consumption, large occupation area, is energy-intensive, and will be accompanied by a large amount of by-products, which causes great burden to the national ecological environment. In contrast, membrane separation can bring lower energy consumption (i.e. operating cost) and lower environmental cost, and is a new emerging separation technology with high efficiency, low energy consumption and environmental friendliness.
[0003] For membrane separation process, membrane material is crucial, among membrane materials, metal organic framework (Metal organic Frameworks, MOFs) is connected by self-assembly of inorganic metal center and bridged organic ligand, and is widely used in gas separation field due to its excellent performance. The advantages of MOFs are: 1. structural diversity, flexible and adjustable pore structure; 2. pore structure close to molecular size, suitable for gas separation pore size; 3. high specific surface area, uniform and high density distribution of pore structure. However, MOFs also have some defects: 1. framework flexibility deformation caused by linker rotation is common in MOFs; 2. intercrystalline defects are inevitable defects of MOF polycrystalline membrane; 3. MOFs have poor stability, which will affect its separation performance under pressure and acid-base conditions. Covalent organic framework (Covalent Organic Frameworks, COFs) is a two-dimensional porous material constructed by organic units. The advantages of COFs are: 1. diversity of building units, adjustable pore structure; 2. space network structure formed by covalent bond, good stability. At the same time, the disadvantage of COF is that its pore size is too large, so the gas separation effect of COFs membrane is not ideal. In summary, MOFs and COFs have complementary advantages and disadvantages, so the preparation of separation membrane by hybridizing MOF / COF two kinds of membrane materials with excellent performance can make the obtained separation membrane have both advantages, good physical and chemical properties, and has broad research prospect. SUMMARY
[0004] The problem to be solved by the present application is how to make the membrane have good physical and chemical properties.
[0005] To solve the above problems, the first aspect of the present application provides a preparation method of a MOF-COF hybrid membrane, comprising the following steps:
[0006] S1: sequentially adding COF nanosheets containing groups capable of interacting with metal ions and metal salt into deionized water, ultrasonic dissolving, mixing uniformly to obtain a precursor solution, and transferring the obtained precursor solution to a carrier to obtain a COF film, wherein the transferring method of the precursor solution is selected from one of suction filtration, spin coating, heating coating, and dip coating;
[0007] S2: immersing the COF film into a growth solution to prepare a MOF-COF hybrid film;
[0008] S3: activating the MOF-COF hybrid film to obtain a MOF-COF hybrid film.
[0009] Preferably, in the step S1, the precursor solution contains 1 part of COF nanosheets and 500-1000 parts of metal ions in terms of molar parts.
[0010] Preferably, the metal ions in the precursor solution are zinc ions and / or cobalt ions.
[0011] Preferably, in the step S1, the carrier is selected from one of an α-Al2O3 carrier, a γ-Al2O3 carrier, an AAO anodic aluminum oxide carrier, a TiO2 carrier, a PAN carrier, and a PVDF carrier.
[0012] Preferably, in the step S2, the growth solution contains a polar solvent, and the polar solvent is selected from one or more of water, methanol, dimethylformamide, dimethylacetamide, and acetonitrile.
[0013] Preferably, in the step S2, the growth solution further contains an organic ligand, and the organic ligand is selected from one or more of imidazole, 2-methylimidazole, imidazole-2-formaldehyde, benzimidazole, 5-methylbenzimidazole, and 2-aminobenzimidazole.
[0014] Preferably, the molar ratio of the metal ions, the organic ligand, and the polar solvent is 1:(2-90):(80-300).
[0015] Preferably, in the step S3, an activating agent is mixed with the MOF-COF hybrid film to activate the MOF-COF hybrid film, and the activating agent is selected from one or more of methanol, chloroform, and acetonitrile. By using a low-boiling-point solvent to replace a high-boiling-point solvent, the residual polar solvent and organic ligand in the film pores are removed.
[0016] Preferably, in the step S1, the COF nanosheets are selected from one of TpHz, COF-1, TpPa-SO3H, TGCOF, TGDha, COF-5, TpAPH, TpASH, Tp-Bdy, and COF-367.
[0017] The MOF in the step S2 is selected from one of ZIF-8, ZIF-67, ZIF-90, ZIF-7, ZIF-76, ZIF-62 and TIF-4.
[0018] Further, the second aspect of the present application provides a MOF-COF hybrid film prepared by the above method.
[0019] The present application has the following beneficial effects: compared with the prior art, the preparation process of the MOF-COF hybrid film provided by the present application is carried out at room temperature, the operation and processing technology are simple, the COF nanosheet and metal ions are first interacted, and then the MOF is grown, so that the distribution of the COF and the MOF is more uniform, and the combination between the COF material and the inorganic carrier can be improved. The whole method has the advantages of simple operation, good repeatability and strong economy. The prepared MOF-COF hybrid film has good continuity, uniform two-phase distribution, compactness and no defects, and has excellent gas separation selectivity and stability. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 The X-ray diffraction characterization result diagram of the product M1 prepared in Example 1 in the specific embodiment of the present application is shown in the figure;
[0021] Figure 2 The scanning electron microscope characterization surface result diagram of the product M1 prepared in Example 1 in the specific embodiment of the present application is shown in the figure;
[0022] Figure 3 The scanning electron microscope characterization cross-section result diagram of the product M1 prepared in Example 1 in the specific embodiment of the present application is shown in the figure;
[0023] Figure 4 The TEM characterization result diagram of the product TpPa-SO3H nanosheet prepared in Example 1 in the specific embodiment of the present application is shown in the figure. DETAILED DESCRIPTION
[0024] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the present application, and are not used to limit the parameter range described in the present application, and the reasonable changes derived therefrom are still within the protection scope of the claims of the present application.
[0025] It should be noted that the endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges and values should be interpreted as being approximate. For numeric values, the endpoints of each range, the endpoints of each range and individual point values, and individual point values can be combined with one another to generate one or more new numeric ranges, which should be considered as being specifically disclosed herein.
[0026] For the convenience of understanding, in the specific embodiments of the present application, the COF film is expressed using C i film, and the MOF-COF hybrid film is expressed using M j film.
[0027] The present application combines the advantages of COF and MOF, and provides a MOF-COF hybrid film, and a preparation method of the MOF-COF hybrid film comprises the following steps:
[0028] S1: preparing COF nanosheets, the COF nanosheets provided in the specific embodiments of the present application have groups that can interact with metal ions; adding the COF nanosheets and metal salt into deionized water, dissolving and mixing uniformly to obtain a precursor solution;
[0029] In the specific embodiments of the present application, the COF nanosheets are selected from one of TpHz, COF-1, TpPa-SO3H, TGCOF, TGDha, COF-5, TpAPH, TpASH, and COF-367
[0030] S2: transferring the precursor solution to a carrier to obtain a C i film, the precursor solution contains 1 part of COF nanosheets and 500-1000 parts of metal ions in terms of molar parts, and the carrier is selected from one of an alpha-Al2O3 carrier, a gamma-Al2O3 carrier, an AAO anodic aluminum oxide carrier, a TiO2 carrier, a PAN carrier, and a PVDF carrier;
[0031] S3: using the C i film to prepare a MOF-COF hybrid film with a growth solution, wherein the growth solution contains a polar solvent selected from one or more of water, methanol, dimethylformamide, dimethylacetamide, and acetonitrile, and the precursor solution further contains an organic ligand selected from one or more of 2-methylimidazole, imidazole-2-carboxaldehyde, and benzimidazole, and the metal ions; the molar ratio of the organic ligand to the polar solvent is 1:(2-90):(80-300);
[0032] S4: activating the MOF-COF hybrid film using an activating agent to obtain a MOF-COF hybrid film, and the activating agent is selected from one or more of methanol, chloroform, and acetonitrile.
[0033] In some preferred embodiments, in the aforementioned step S3, in the most preferred scheme, the molar ratio of metal ions to 2-methylimidazole and N,N-dimethylacetamide in the growth solution is 1:45:90, based on the metal ions in the precursor solution.
[0034] Example 1 Preparation of ZIF-8-TpPa-SO3H membrane
[0035] The TpPa-SO3H nanosheets prepared by the two-phase method were dialyzed in deionized water for 3 days to obtain TpPa-SO3H nanosheets uniformly dispersed in water with a mass concentration of 0.003 g / ml.
[0036] The TpPa-SO3H nanosheet aqueous dispersion and zinc nitrate hexahydrate were mixed and added to deionized water to be ultrasonically dissolved and uniformly dispersed to obtain a precursor solution. The molar ratio of TpPa-SO3H to Zn in the precursor solution was 1:600. The TpPa-SO3H nanosheet dispersion combined with Zn 2+ was used as a precursor solution, and the precursor solution was suction-filtered onto an alumina carrier to prepare COF membranes, which were respectively denoted as C1, C2, and C3.
[0037] 2-methylimidazole was taken and dissolved in DMF to obtain a growth solution. Based on the Zn 2+ in the precursor solution, the molar ratio of Zn 2+ to 2-methylimidazole and DMF in the growth solution was 1:45:90.
[0038] C1-C3 were immersed in the growth solution, and after 6 hours of reaction at room temperature, they were taken out, activated in methanol for 2 hours, and dried at room temperature for 3 hours. The prepared ZIF-8-TpPa-SO3H membrane products were repeated three times and were respectively denoted as product M1, product M2, and product M3.
[0039] Characterization of ZIF-8-TpPa-SO3H membrane: The products M1-M3 prepared above were subjected to XRD, SEM characterization, and determination of separation selectivity and permeability. The XRD characterization results of product M1 are shown in Figure 1 , the SEM characterization results of product M1 are shown in Figure 2 , Figure 3 , and the TEM characterization results of TpPa-SO3H nanosheets are shown in Figure 4 .
[0040] The propylene / propane separation selectivity and permeability detection results of products M1-M3 are shown in Table 1. As shown in Table 1, the ZIF-8-TpPa-SO3H membrane has excellent propylene / propane separation performance.
[0041] Table 1 Determination results of propylene permeability and propylene / propane selectivity of ZIF-TpPa-SO3H
[0042]
[0043] Example 2 Preparation of ZIF-67-TpPa-SO3H membrane
[0044] The TpPa-SO3H nanosheet aqueous dispersion prepared in Example 1 was mixed with cobalt nitrate tetrahydrate and ultrasonically dissolved in deionized water to obtain a precursor solution, wherein the molar ratio of TpPa-SO3H to Co in the precursor solution was 1:600. The precursor solution was heated and coated onto the AAO carrier to obtain membranes, which were named C4, C5, and C6.
[0045] 2-methylimidazole was added to DMAc to obtain a growth solution. The molar ratio of Zn 2+ was taken as a reference, and the molar ratio of Co 2+ to 2-methylimidazole in the growth solution to DMAc was 1:45:90.
[0046] C4-C6 were immersed in the precursor solution, and after 6 hours of reaction at room temperature, they were taken out, activated in methanol for 2 hours, and dried at room temperature for 3 hours to obtain ZIF-67-TpPa-SO3H membrane products. The experiment was repeated three times, and the obtained products were named product M4, product M5, and product M6, respectively.
[0047] Characterization of ZIF-67-TpPa-SO3H membrane: The separation selectivity and permeability of the products M4-M6 prepared above were determined. The propylene / propane separation selectivity and permeability detection results of the products M4-M6 are shown in Table 2.
[0048] Table 2 ZIF-67-TpPa-SO3H membrane propylene permeability and propylene / propane selectivity determination results
[0049]
[0050] Example 3 Preparation of ZIF-90-COF-1 membrane
[0051] COF-1 nanosheets were prepared, and the nanosheets were dispersed in deionized water by ultrasonic treatment to obtain a COF-1 nanosheet dispersion.
[0052] The COF-1 nanosheet aqueous dispersion and zinc nitrate hexahydrate were sequentially added to deionized water and ultrasonically dissolved to obtain a precursor solution, wherein the molar ratio of COF-1 to Zn in the precursor solution was 1:800. The COF-1 nanosheets combined with Zn 2+ were obtained as a precursor solution, and the precursor solution was spin-coated onto an alumina carrier to obtain membranes, which were named C7, C8, and C9.
[0053] Imidazole-2-carboxaldehyde was taken into DMAc to be fully dissolved to obtain a growth solution, and the molar ratio of Zn 2+ was taken as a reference, and the molar ratio of Zn 2+ and imidazole-2-carboxaldehyde in the growth solution was 1:25:80.
[0054] C7-C9 membranes were immersed in the growth solution. After 6 hours of reaction at room temperature, they were taken out, activated in methanol for 2 hours, and dried at room temperature for 3 hours to obtain ZIF-90-COF-1 membranes. The experiment was repeated three times, and the obtained products were respectively marked as product M7, product M8 and product M9.
[0055] Characterization of ZIF-90-COF-1 membranes: The separation selectivity and permeability of the above-prepared products M7-M9 were determined. The results of the n-butane permeability and n-isobutane selectivity of products M7-M9 are shown in Table 3.
[0056] Table 3. Results of n-butane permeability and n-isobutane selectivity of ZIF-90-COF-1 membranes
[0057]
[0058] Example 4. Preparation of ZIF-7-COF-367 membranes
[0059] COF-367 nanosheets were prepared by a conventional solvothermal method and were ultrasonically dispersed in deionized water to obtain a COF-367 nanosheet dispersion. Concentration by rotary evaporation obtained a COF-367 nanosheet dispersion with a mass concentration of 0.003 g / ml.
[0060] The COF-367 nanosheet aqueous dispersion and zinc nitrate hexahydrate were sequentially added to deionized water and ultrasonically dissolved to obtain a precursor solution. The precursor solution was suction-filtered onto a PAN support, and the obtained product was marked as C 10 , C 11 , C 12 The molar ratio of COF-367 and Zn in the precursor solution was 1:550.
[0061] Benzimidazole was taken into methanol to be fully dissolved to obtain a growth solution, and the molar ratio of Zn 2+ was taken as a reference, and the molar ratio of Zn 2+ and benzimidazole in the growth solution was 1:12:150.
[0062] C 10 -C 12 membranes were immersed in the growth solution. After 3 hours of reaction at 70°C, they were taken out, activated in acetone for 2 hours, and dried at room temperature for 3 hours to obtain ZIF-7-COF-367 membranes. The experiment was repeated three times, and the obtained products were respectively marked as product M 10 , product M11 and product M 12 .
[0063] Characterization of ZIF-7-COF-367 membranes: The product M 10 ~M 12 was subjected to separation selectivity and permeance determination. The hydrogen / methane separation selectivity and permeance of product M 10 ~M 12 were determined and the results are shown in Table 4.
[0064] Table 4 Hydrogen permeance and hydrogen / methane selectivity determination results of ZIF-7-COF-367 membranes
[0065]
[0066] Example 5 Preparation of ZIF-8-TpAPH membranes
[0067] The diamine and p-toluenesulfonic acid were mixed by solid phase grinding to obtain a viscous salt. Then, the 1,3,5-triformylphloroglucinol was added to the viscous salt by hydrothermal method to prepare TpAPH nanosheets, and finally the TpAPH nanosheet dispersion was obtained by ultrasonic dispersion in deionized water.
[0068] The TpAPH nanosheet aqueous dispersion and a certain amount of zinc nitrate hexahydrate were sequentially added to deionized water and ultrasonically dissolved, and after uniform dispersion, a precursor solution was obtained, in which the molar ratio of TpAPH nanosheets to Zn was 1:600.
[0069] The precursor solution was suction-filtered onto an alumina carrier to obtain a product, which was denoted as product C 13 , product C 14 , product C 15 .
[0070] 2-methylimidazole was taken and dissolved in DMF to obtain a growth solution. The molar ratio of Zn 2+ to 2-methylimidazole in the growth solution to DMF was 1:45:90, based on the Zn 2+ in the precursor solution.
[0071] The membrane layer obtained after suction filtration was immersed in the growth solution, and after 6 hours of reaction at room temperature, it was taken out, activated in methanol for 2 hours, and dried at room temperature for 3 hours to obtain a ZIF-8-TpAPH membrane. The membrane products obtained in three repeated experiments were denoted as product M 10 , product M 11 , and product M 12 .
[0072] Characterization of ZIF-8-TpAPH membranes: The product M 13 ~M 15The separation selectivity and permeability were determined. The separation selectivity and permeability of propylene / propane of the product M 13 ~M 15 are shown in Table 5.
[0073] Table 5. The propylene permeability and propylene / propane selectivity determination results of ZIF-8-TpAPH membrane
[0074]
[0075] Example 6. Preparation of ZIF-8-TpPa-SO3H membrane with different reaction time
[0076] The TpPa-SO3H nanosheet aqueous dispersion and zinc nitrate hexahydrate were mixed and ultrasonically dissolved in deionized water to obtain a precursor solution, and the molar ratio of TpPa-SO3H to Zn in the precursor solution was 1:600. The TpPa-SO3H nanosheet dispersion combined with Zn 2+ was obtained as a precursor solution, and the precursor solution was suction filtered onto an alumina carrier to obtain products C 16 , C 17 , C 18 , C 19 , and C 20 .
[0077] 2-methylimidazole was taken and dissolved in DMF to obtain a growth solution. Based on the Zn 2+ in the precursor solution, the molar ratio of Zn 2+ to 2-methylimidazole and DMF in the growth solution was 1:45:90.
[0078] C 16 -C 20 were immersed in the growth solution, and reacted at room temperature for 1, 3, 6, 9, and 12 hours, respectively, and then activated in methanol for 2 hours, and dried at room temperature for 3 hours to obtain ZIF-8-TpPa-SO3H membranes, which were denoted as products M 16 , M 17 , M 18 , M 19 , and M 20 .
[0079] The separation selectivity and permeability were determined for the products M 16 -M 20 prepared above. The separation selectivity and permeability of propylene / propane of the product M 16 -M 20The detection results of propylene / propane separation selectivity and permeation rate of the ZIF-8-TpPa-SO3H membranes prepared at different reaction times are shown in Table 6. As can be seen from the results in Table 6, the propylene / propane separation performance of the ZIF-8-TpPa-SO3H membranes increases with the increase of the reaction time of the crystallization, while the propylene permeation rate decreases.
[0080] Table 6 Performance test results of ZIF-8-TpPa-SO3H membranes prepared at different reaction times
[0081]
[0082] Example 7 Preparation of ZIF-8-TpPa-SO3H membranes at different reaction temperatures
[0083] The TpPa-SO3H nanosheet aqueous dispersion and zinc nitrate hexahydrate were mixed and ultrasonically dissolved in deionized water to obtain a precursor solution, and the molar ratio of TpPa-SO3H to Zn in the precursor solution was 1:600. The TpPa-SO3H nanosheet dispersion combined with Zn 2+ was obtained as a precursor solution, and the precursor solution was suction-filtered onto the alumina carrier to obtain a product, which was denoted as product C 21 , product C 22 , product C 23 , product C 24 , product C 25 , product C 26 .
[0084] 2-methylimidazole was taken and dissolved in DMF to obtain a growth solution. Based on the Zn 2+ in the precursor solution, the molar ratio of Zn 2+ to 2-methylimidazole and DMF in the growth solution was 1:45:90.
[0085] The product C 21 -C 26 was immersed in the growth solution, and was taken out after reaction at 10℃, 30℃, 60℃, 80℃, 120℃ and 150℃ for 6 hours, respectively. The product was activated in methanol for 2 hours, and was dried at room temperature for 3 hours to obtain a ZIF-8-TpPa-SO3H membrane, which was denoted as product M 21 , product M 22 , product M 23 , product M 24 , product M 25 , product M 26 .
[0086] The ZIF-8-TpPa-SO3H membranes were characterized: the separation selectivity and permeation rate of the products M 21 ~M 26 prepared above were determined. The products M 21 -M 26The detection results of the propylene / propane separation selectivity and permeation rate of the ZIF-8-TpPa-SO3H membranes prepared at different reaction temperatures are shown in Table 7. As can be seen from the results in Table 7, the ZIF-8-TpPa-SO3H membrane prepared by reaction crystallization at 30℃ has good propylene / propane gas separation performance.
[0087] Table 7 Performance test results of ZIF-8-TpPa-SO3H membranes prepared at different reaction temperatures
[0088]
[0089] Example 8 Preparation of ZIF-8-TpPa-SO3H membranes in different polar solvents
[0090] The TpPa-SO3H nanosheet aqueous dispersion and zinc nitrate hexahydrate were mixed and ultrasonically dissolved in deionized water to obtain a precursor solution, and the molar ratio of TpPa-SO3H to Zn in the precursor solution was 1:600. The TpPa-SO3H nanosheet dispersion combined with Zn 2+ was obtained as a precursor solution, and the precursor solution was suction filtered onto an alumina carrier to obtain products marked as C 27 , C 28 , C 29 , and C 30 .
[0091] 2-Methylimidazole was dissolved in a polar solvent to prepare a growth solution, and the selected polar solvents were N,N-dimethylacetamide, methanol, deionized water, and N,N-dimethylformamide. With Zn 2+ in the precursor solution as a reference, the molar ratio of Zn 2+ in the precursor solution to 2-methylimidazole in the growth solution to the polar solvent was 1:45:(80-300).
[0092] C 27 -C 30 were immersed in the growth solution, and after 6 hours of reaction at room temperature, they were taken out, activated in methanol for 2 hours, and dried at room temperature for 3 hours to obtain ZIF-8-TpPa-SO3H membranes, which were marked as product M 27 (polar solvent: N,N-dimethylacetamide), product M 28 (polar solvent: methanol), product M 29 (polar solvent: deionized water), and product M 30 (polar solvent: N,N-dimethylformamide).
[0093] Characterization of ZIF-8-TpPa-SO3H membranes: The separation selectivity and permeation rate of the products M 27 -M 30 prepared above were determined. The products M 27 -M 30The detection results of propylene / propane separation selectivity and permeation rate of the ZIF-8-TpPa-SO3H membranes prepared by using different polar solvents as the solvent of the growth solution are shown in Table 8. As can be seen from the results in Table 8, the ZIF-8-TpPa-SO3H membrane prepared by using DMF as the solvent of the growth solution has good propylene / propane gas separation performance.
[0094] Table 8 Performance test results of ZIF-8-TpPa-SO3H membranes prepared by using different polar solvents
[0095]
[0096]
[0097] Preparation of different pure COF filter membranes
[0098] TpHz, COF-1, TpPa-SO3H, COF-367 and TGDha nanosheets were prepared respectively and were uniformly dispersed in deionized water. Each kind of COF nanosheet was suction filtered on two pieces of alumina carriers. The obtained COF filter membranes were immersed in methanol and naturally dried. The obtained pure COF filter membrane product was recorded as product M 31 , product M 32 , product M 33 , product M 34 , product M 35 , product M 36 , product M 37 , product M 38 , product M 39 , product M 40 .
[0099] The separation selectivity and permeation rate of the products M 31 -M 40 prepared above were determined. The detection results of propylene / propane separation selectivity and permeation rate of the products M 31 -M 40 are shown in Table 9. As can be seen from the results in Table 9, the gas separation effect of the pure COF filter membrane is not ideal.
[0100] Table 9 Performance test results of different pure COF filter membranes
[0101]
[0102] Preparation of pure ZIF-8 membrane
[0103] An equal amount of zinc nitrate hexahydrate as that in Example 1 was mixed and added into deionized water to be ultrasonically dissolved and uniformly dispersed to obtain a precursor solution. The precursor solution was suction filtered onto an alumina carrier to prepare a filter membrane, which was recorded as C 41 , C 42 , C 43 .
[0104] Take 2-methylimidazole into DMF to dissolve thoroughly to obtain a growth solution, and the molar ratio of Zn 2+ as a reference, Zn 2+ and the molar ratio of 2-methylimidazole to DMF in the growth solution is 1:45:90.
[0105] C 41 -C 43 immersed in the growth solution, and after 6 hours of reaction at room temperature, the product was taken out, activated in methanol for 2 hours, and dried at room temperature for 3 hours. The prepared ZIF-8 membrane product was repeated three times and was recorded as product M 41 , product M 42 , and product M 43 .
[0106] The ZIF-8 membrane was characterized: the separation selectivity and permeability of the above-prepared product M 41 -M 43 were determined. The separation selectivity and permeability detection results of the product M 41 -M 43 are shown in Table 10. As can be seen from the results in Table 10, the gas separation effect of the pure ZIF-8 membrane under the same conditions is not ideal.
[0107] Table 10 Performance test results of pure ZIF-8 membrane prepared by the same method
[0108]
[0109] As can be seen from the experimental results of Comparative Examples 1-8 and Comparative Examples 1-2, the MOF-COF hybrid membrane has better gas selective permeability than the single MOF membrane or COF membrane.
[0110] Unless otherwise defined, all terms, symbols and other scientific terminology used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. In some cases, terms, which are commonly understood by one of ordinary skill in the art, are defined herein for the sake of clarity and convenience. Such definitions should not be interpreted to limit the scope of the disclosure.
[0111] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited to this. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will fall within the protection scope of the present disclosure.
Claims
1. A method for preparing a MOF-COF hybrid membrane, characterized in that, Includes the following steps: S1: Contains substances that can interact with Zn 2+ and / or Co 2+ COF nanosheets with interacting electronegative groups and metal salts are sequentially added to deionized water and dissolved by ultrasonication. After being mixed evenly, a precursor solution is obtained. The COF nanosheets are selected from any one of TpPa-SO3H, COF-1, COF-367, and TpAPH. The obtained precursor solution is transferred to a support to obtain a COF membrane. The transfer method of the precursor solution is selected from one of vacuum filtration, spin coating, heat coating, and dip coating. S2: MOF-COF hybrid membrane is prepared by immersing the COF membrane in the growth solution at room temperature. The growth solution is composed of a polar solvent and an organic ligand. The COF membrane can react with the growth solution to generate MOF. The MOF is selected from one of ZIF-8, ZIF-67, ZIF-90, ZIF-7, ZIF-76, and ZIF-62. S3: Activate the MOF-COF hybrid membrane to obtain the MOF-COF hybrid membrane.
2. The method for preparing the MOF-COF hybrid membrane as described in claim 1, characterized in that, In step S1, the molar ratio of COF nanosheets to metal salt in the precursor solution is 1:(500~1000).
3. The method for preparing the MOF-COF hybrid membrane as described in claim 1, characterized in that, The metal salt in the precursor solution is a zinc salt and / or a cobalt salt.
4. The method for preparing the MOF-COF hybrid membrane as described in claim 1, characterized in that, In step S1, the support is selected from one of α-Al2O3 support, γ-Al2O3 support, AAO anodic aluminum oxide support, TiO2 support, PAN support, and PVDF support.
5. The method for preparing the MOF-COF hybrid membrane as described in claim 1, characterized in that, In step S2, the polar solvent is selected from one or more of water, methanol, dimethylformamide, dimethylacetamide, and acetonitrile.
6. The method for preparing the MOF-COF hybrid membrane as described in claim 1, characterized in that, The organic ligand in step S2 is selected from one or more of imidazole, 2-methylimidazolium, imidazole-2-carboxaldehyde, benzimidazole, 5-methylbenzimidazole, and 2-aminobenzimidazole.
7. The method for preparing the MOF-COF hybrid membrane as described in claim 1, characterized in that, The molar ratio of the metal salt, organic ligand, and polar solvent is 1:(2~90):(80~300).
8. The method for preparing the MOF-COF hybrid membrane as described in claim 1, characterized in that, In step S3, the activator is mixed with the MOF-COF hybrid membrane to activate the MOF-COF hybrid membrane. The activator is selected from one or more of methanol, chloroform, and acetonitrile.
9. A MOF-COF hybrid membrane, characterized in that, The MOF-COF hybrid membrane is prepared by any of the preparation methods described in claims 1 to 8.