A method for constructing a decarboxylation mixed matrix membrane based on in-situ thermal induction

Abstract

The application discloses a method for constructing a decarboxylated mixed matrix membrane based on in-situ thermal induction, and belongs to the technical field of mixed matrix membrane preparation. The steps of the in-situ thermal induction construction method comprise the following steps: dissolving a carboxylic acid ligand and a metal salt respectively, mixing the two to obtain a MOF precursor solution; performing heat treatment on the MOF precursor solution to obtain MOF nanosheets; blending the MOF nanosheets with a polymer in a solvent to prepare a casting solution; using the casting solution to prepare a mixed matrix membrane; and finally in-situ thermal induction decarboxylation of the mixed matrix membrane, and cooling to obtain a decarboxylated mixed matrix membrane. The method provided by the application can prepare a high-performance mixed matrix membrane while keeping the framework of the MOF nanosheets intact, and solves the problems of low flux, small porosity and low selectivity of the existing mixed matrix membrane; the prepared decarboxylated mixed matrix membrane has channels allowing the diffusion of target molecules and high target molecule selectivity.

Description

Technical Field

[0001] This invention belongs to the field of mixed matrix membrane preparation technology, specifically relating to a method for constructing a decarboxylation mixed matrix membrane based on in-situ thermal induction. Background Technology

[0002] Excessive greenhouse gas emissions have led to a variety of environmental problems, including global warming, ocean acidification, and ecological damage. With population growth and industrial progress, the concentration of greenhouse gases in the atmosphere, especially carbon dioxide, is constantly increasing. In addition to developing carbon-free clean energy sources, capturing carbon dioxide from the combustion exhaust of natural gas and flue gas is also crucial. Traditional carbon dioxide capture technologies, such as absorption, cryogenic distillation, and condensation, are energy-intensive and uneconomical. Compared to traditional carbon dioxide capture technologies, membrane separation processes have inherent advantages such as high energy efficiency, high reliability, and small footprint. However, traditional polymer membranes often have limitations in permeability and selectivity. High aspect ratio metal-organic frameworks (MOFs) nanomaterials with nanometer thickness, assembled into MOF nanosheet membranes through discrete stacking, have shown remarkable performance in hydrogen purification and hydrocarbon separation, easily exceeding the Robeson upper limit. However, MOF membranes based on discrete crystal stacking face challenges that limit their applicability, such as membrane integrity, mechanical stability, and complex manufacturing and processing. Furthermore, due to the mechanical stability of nanosheets, it is difficult to design MOF nanosheets with pore sizes suitable for carbon dioxide capture. To address these issues, hybrid matrix membranes (MMMs) have been proposed for gas separation. However, the synthesis of conventional MOFs typically produces nearly undispersed agglomerated powders composed of nanoparticles, complicating their integration into the polymer, limiting the fusion of the two components, and ultimately increasing non-selective channels. Furthermore, their advantages are only apparent when doped with high MOF loadings, which may affect the mechanical integrity of the composite. High aspect ratio MOF nanostructures can improve the fusion between the two components in the composite, thus circumventing the aforementioned obstacles.

[0003] Most polymers possess sufficient flexibility and rotational freedom to rearrange themselves to maximize cohesive interactions, preventing the formation of micropores and network structures that lead to low permeability. However, the doping of nanosheets has a relatively small effect on improving permeability. Therefore, developing a simple and effective method to improve the permeability and selectivity of hybrid matrix membranes is currently a key issue. Summary of the Invention

[0004] The purpose of this invention is to provide a method for constructing a decarboxylation hybrid matrix membrane based on in-situ thermal induction. This method can prepare a high-performance hybrid matrix membrane while maintaining the MOF nanosheet framework intact, solving the problems of low flux, low porosity, and low selectivity existing in current hybrid matrix membranes. During the decarboxylation step of the preparation process, a large amount of gas escapes, forming a molecular sieve network within the polymer and exposing a large number of metal sites. This gives the prepared in-situ decarboxylation hybrid matrix membrane channels that allow target molecule diffusion and high target molecule selectivity, resulting in excellent separation performance when used for gas separation.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] One of the technical solutions of this invention is to provide a method for constructing a decarboxylation mixed matrix membrane based on in-situ thermal induction, comprising the following steps:

[0007] The carboxylic acid ligand and the metal salt were dissolved and mixed to obtain a MOF precursor solution. The MOF precursor solution was heat-treated to obtain MOF nanosheets. The MOF nanosheets were mixed with the polymer in a solvent to prepare a casting solution. A mixed matrix membrane was prepared using the casting solution. Finally, the mixed matrix membrane was decarboxylated by treating it at 230-250°C for 1-36 hours. After cooling, the decarboxylated mixed matrix membrane was obtained.

[0008] Preferably, the solvent for dissolving the carboxylic acid ligand and the metal salt is a mixture of N,N-dimethylformamide (DMF) and acetonitrile in a volume ratio of 15:1.

[0009] Preferably, the molar ratio of the carboxylic acid ligand to the metal salt is 1–55:1; and the concentration of the metal ion in the MOF precursor solution is 0.5–50.8 mmol·L⁻¹. -1 .

[0010] The conditions defined in this invention can be used to prepare ultrathin MOF nanosheets with preferred orientation and high aspect ratio, with an aspect ratio of up to 1800.

[0011] Preferably, the carboxylic acid ligand is 2,5-dibromoterephthalic acid, 2,5-dihydroxyterephthalic acid, or terephthalic acid; the metal salt is a divalent or trivalent metal salt.

[0012] Preferably, the heat treatment temperature is 30–100°C and the time is 1–100 min.

[0013] More preferably, the heat treatment method is microwave heating.

[0014] Microwave heating can accelerate the nucleation rate and save reaction time.

[0015] Preferably, the MOF nanosheets further include a cleaning step before the casting solution is prepared.

[0016] More preferably, the washing solution in the cleaning step is DMF and chloroform / dichloromethane; specifically, the prepared MOF nanosheets are dispersed in DMF, shaken thoroughly, centrifuged, and repeated 3-4 times; then the DMF cleaning method is repeated with chloroform or dichloromethane, also 3-4 times. The purpose of cleaning is to remove physically attached guest molecules.

[0017] Preferably, the polymer is selected from polysulfone (PSF), polyimide (PI), polyethylene oxide (PEO), microporous polymer (PIM), or polyvinylidene fluoride (PVDF); the solvent of the casting solution is N,N-dimethylformamide, chloroform, dichloromethane, or methanol; the mass fraction of MOF nanosheets in the casting solution is 0.1-30%, and the mass fraction of the polymer is 1-40%.

[0018] Preferably, the cooling rate does not exceed 5°C / min.

[0019] The second technical solution of the present invention provides a decarboxylation mixed matrix membrane prepared according to the above-mentioned method of in-situ thermally induced construction of decarboxylation mixed matrix membrane.

[0020] The third technical solution of the present invention provides an application of the above-mentioned decarboxylation mixed matrix membrane in gas separation.

[0021] The beneficial technical effects of the present invention are as follows:

[0022] (1) Compared with conventional methods for preparing mixed matrix films through doping, the method provided by this invention has milder conditions and is simpler to operate. This invention prepares decarboxylation mixed matrix films by in-situ thermal induction to break the coordination bonds between carboxylic acid ligands and metals, while simultaneously ensuring a stable nanosheet framework system.

[0023] (2) This invention is the first to prepare decarboxylation mixed matrix membranes in situ by thermal induction, which solves the fundamental problems of low porosity and low flux of mixed matrix membranes.

[0024] (3) Compared to mixed matrix films prepared by conventional doping, the in-situ decarboxylation mixed matrix film prepared by the method provided in this invention maximizes the specific surface area and porosity of the nanosheets by breaking the coordinate bonds, while exposing a large number of metal sites that can interact with target molecules to improve the selectivity of gas molecules. In addition, during the decarboxylation process, the release of CO2 gas molecules due to the breaking of the carboxyl coordination bonds between metal ions and the ligands themselves can form a molecular sieve network in the polymer matrix, which greatly increases the pore volume of the polymer and facilitates the diffusion of target molecules.

[0025] (4) The decarboxylation mixed matrix membrane constructed by in-situ thermal induction in this invention has a significantly improved permeability; compared with the currently reported commercial polymer-based membranes, it exhibits good CO2 / CH4 and CO2 / N2 selectivity and has broad application prospects. Attached Figure Description

[0026] Figure 1 This is a TEM image of the decarboxylated mixed matrix membrane prepared in Example 1.

[0027] Figure 2 This is a SEM image of the decarboxylated mixed matrix membrane prepared in Example 2. Detailed Implementation

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0029] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0030] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0031] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0032] Example 1

[0033] Preparation of decarboxylation mixed matrix membrane:

[0034] (1) Dissolve 0.21 g of 2,5-dihydroxyterephthalic acid in 28 mL of a mixed solution of DMF and acetonitrile (V DMF :V 乙腈 The concentration obtained in the ratio of 3:1 was 37.9 mmol / L. -1 Solution A. Dissolve 0.07 g of copper nitrate trihydrate in 28 mL of a mixed solution of DMF and acetonitrile (V DMF :V 乙腈A concentration of 10.3 mmol / L was obtained in a ratio of 1:3. -1 Solution B. Solutions A and B were dissolved separately by sonication for 2 minutes. Solution B was then added to solution A to obtain the MOF precursor solution.

[0035] (2) The obtained precursor solution was poured into a microwave reactor and placed in a microwave reactor for heat treatment at 50°C for 30 min; brown MOF (CuBDC-(OH)2) nanosheets were formed in the reactor. After natural cooling, the nanosheets were dispersed in 25 mL of DMF solution and centrifuged at 10000 rpm for 30 min. This process was repeated 3 times, and then washed 3 times with chloroform (in the same way as DMF washing). The obtained MOF nanosheets were dispersed in chloroform solution and stored.

[0036] (3) Disperse the MOF nanosheet dispersion prepared in step (2) in chloroform, wherein the mass fraction of MOF nanosheets is 1%, and stir for 20 min to ensure thorough dispersion; then add 10 wt% PI polymer powder while stirring to prevent polymer powder aggregation. Stir the mixed casting solution at room temperature for 24 h to ensure thorough mixing and dispersion; ultrasonically treat the stirred casting solution for 1 h to degas. Finally, cast the treated casting solution using a casting method. When casting the solution into the petri dish, the speed should be fast to prevent the solvent from evaporating too quickly and causing film defects. Finally, allow it to air dry at room temperature.

[0037] (4) Transfer the membrane from step (3) to a forced-air drying oven for heat treatment at 240°C for 24 hours. During the heat treatment, use a glass plate to press the mixed matrix membrane to prevent the membrane from curling. Then, perform slow annealing at a cooling rate of 3°C / min to prevent defects from forming.

[0038] Figure 1 This is a TEM image of the decarboxylation mixed matrix membrane prepared in Example 1. Figure 1 As shown, the presence of CuO lattice fringes in the TEM image indicates that the prepared CuBDC-(OH)2 nanosheets have been successfully decarboxylated in the polymer matrix.

[0039] Example 2

[0040] Preparation of decarboxylation mixed matrix membrane:

[0041] (1) Dissolve 0.21 g of 2,5-dihydroxyterephthalic acid in 28 mL of a mixed solution of DMF and acetonitrile (V DMF :V 乙腈 The concentration obtained in the ratio of 3:1 was 37.9 mmol / L. -1 Solution A. Dissolve 0.07 g of copper nitrate trihydrate in 28 mL of a mixed solution of DMF and acetonitrile (V DMF:V 乙腈 A concentration of 10.3 mmol / L was obtained in a ratio of 1:3. -1 Solution B. Solutions A and B were dissolved separately by sonication for 2 minutes. Solution B was then added to solution A to obtain the MOF precursor solution.

[0042] (2) The obtained precursor solution was poured into a microwave reactor and placed in a microwave reactor for heat treatment at 50°C for 30 min; brown MOF (CuBDC-(OH)2) nanosheets were formed in the reactor. After natural cooling, the nanosheets were dispersed in 25 mL of DMF solution and centrifuged at 10000 rpm for 30 min. This process was repeated 3 times, and then washed 3 times with chloroform (in the same way as DMF washing). The obtained MOF nanosheets were dispersed in chloroform solution and stored.

[0043] (3) Disperse the MOF nanosheet dispersion prepared in step (2) in chloroform, wherein the mass fraction of MOF nanosheets is 1%, and stir for 20 min to ensure thorough dispersion; then add 10 wt% PI polymer powder while stirring to prevent polymer powder aggregation. Stir the mixed casting solution at room temperature for 24 h to ensure thorough mixing and dispersion; ultrasonically treat the stirred casting solution for 1 h to degas. Finally, cast the treated casting solution using a casting method. When casting the solution into the petri dish, the speed should be fast to prevent the solvent from evaporating too quickly and causing film defects. Finally, allow it to air dry at room temperature.

[0044] (4) Transfer the membrane from step (3) to a forced-air drying oven for heat treatment at 240°C for 24 hours. During the heat treatment, use a glass plate to press the mixed matrix membrane to prevent the membrane from curling. Then, perform slow annealing at a cooling rate of 3°C / min to prevent defects from forming.

[0045] The decarboxylation mixed matrix membrane constructed based on in-situ thermal induction in this embodiment is applied to gas separation:

[0046] The prepared decarboxylated mixed matrix membrane was sealed with epoxy resin in a permeation cell for gas separation testing. An equimolar mixture of CO2 / N2 or CO2 / CH4 was injected into the shell side of the mixed matrix membrane for gas permeation. A 1:1 mixed gas was added to the feed side of the membrane, and the permeate gas was removed from the permeate side using scavenging gas (Ar). The gas separation performance was calculated after detection using an Agilent gas chromatograph 7890A.

[0047] Figure 2 This is a SEM image of the decarboxylated mixed matrix membrane prepared in Example 2.

[0048] The decarboxylated mixed matrix membrane prepared in this embodiment has a CO2 flux of 143 Barrer and CO2 / N2 or CO2 / CH4 selectivity as high as 204.1 and 236.3, respectively. Both permeability and selectivity are increased by 4 times compared with the undecarboxylated mixed matrix membrane. Compared with the currently reported MOF / polymer and MOF nanosheet / polymer mixed matrix membranes, the decarboxylated mixed matrix membrane exhibits the highest CO2 / CH4 and CO2 / N2 selectivity. This result indicates that the mixed matrix membrane prepared in this invention has excellent performance and good application prospects.

[0049] Example 3

[0050] Preparation of decarboxylation mixed matrix membrane:

[0051] (1) Dissolve 0.21 g of 2,5-dibromoterephthalic acid in 28 mL of a mixed solution of DMF and acetonitrile (V DMF :V 乙腈 The concentration obtained in the ratio of 3:1 was 23.2 mmol / L. -1 Solution A. Dissolve 0.005 g of copper nitrate trihydrate in 28 mL of a mixed solution of DMF and acetonitrile (V DMF :V 乙腈 The concentration obtained in the ratio of 1:3 was 0.74 mmol / L. -1 Solution B. Solutions A and B were dissolved separately by sonication for 2 minutes. Solution B was then added to solution A to obtain the MOF precursor solution.

[0052] (2) The obtained precursor solution was poured into a microwave reactor and placed in a microwave reactor for heat treatment at 80°C for 30 min; light blue MOF (CuBDC-(Br)2) nanosheets were formed in the reactor. After natural cooling, the nanosheets were dispersed in 25 mL of DMF solution and centrifuged at 10000 rpm for 30 min. This process was repeated 3 times, and then washed 3 times with dichloromethane (in the same way as DMF washing). The obtained MOF nanosheets were dispersed in dichloromethane solution and stored.

[0053] (3) Disperse the MOF nanosheet dispersion prepared in step (2) in dichloromethane, wherein the mass fraction of MOF nanosheets is 1%, and stir for 20 min to ensure thorough dispersion; then add 10 wt% PI polymer powder while stirring to prevent polymer powder aggregation. Stir the mixed casting solution at room temperature for 24 h to ensure thorough mixing and dispersion; ultrasonically treat the stirred casting solution for 1 h to degas. Finally, cast the treated casting solution using a casting method. When casting the solution into the petri dish, the speed should be fast to prevent the solvent from evaporating too quickly and causing membrane defects. Finally, allow it to air dry at room temperature.

[0054] (4) Transfer the membrane from step (3) to a forced-air drying oven for heat treatment at 240°C for 24 hours. During the heat treatment, use a glass plate to press the mixed matrix membrane to prevent the membrane from curling. Then, perform slow annealing at a cooling rate of 3°C / min to prevent defects from forming.

[0055] The decarboxylation mixed matrix membrane constructed based on in-situ thermal induction in this embodiment is applied to gas separation:

[0056] The prepared decarboxylated mixed matrix membrane was sealed with epoxy resin in a permeation cell for gas separation testing. An equimolar mixture of CO2 / N2 or CO2 / CH4 was injected into the shell side of the mixed matrix membrane for gas permeation. A 1:1 mixed gas was added to the feed side of the membrane, and the permeate gas was removed from the permeate side using scavenging gas (Ar). The gas separation performance was calculated after detection using an Agilent gas chromatograph 7890A.

[0057] The decarboxylated mixed matrix membrane prepared in this embodiment has a CO2 flux of 136 Barrer and CO2 / N2 or CO2 / CH4 selectivity as high as 198.5 and 156.2, respectively, indicating that the mixed matrix membrane prepared by this invention has excellent performance and good application prospects.

[0058] Example 4

[0059] Preparation of decarboxylation mixed matrix membrane:

[0060] (1) Dissolve 0.21 g of 2,5-dichloroterephthalic acid in 28 mL of a mixed solution of DMF and acetonitrile (V DMF :V 乙腈 The concentration obtained in the ratio of 3:1 was 31.9 mmol / L. -1 Solution A. Dissolve 0.007 g of copper nitrate trihydrate in 28 mL of a mixed solution of DMF and acetonitrile (V DMF :V 乙腈 The concentration obtained in the ratio of 1:3 was 1.03 mmol / L. -1 Solution B. Solutions A and B were dissolved separately by sonication for 2 minutes. Solution B was then added to solution A to obtain the MOF precursor solution.

[0061] (2) The obtained precursor solution was poured into a microwave reactor and placed in a microwave reactor for heat treatment at 70°C for 30 min; light blue MOF (CuBDC-(Cl)2) nanosheets were formed in the reactor. After natural cooling, the nanosheets were dispersed in 25 mL of DMF solution and centrifuged at 10000 rpm for 30 min. This process was repeated 3 times, and then washed 3 times with chloroform (in the same way as DMF washing). The obtained MOF nanosheets were dispersed in chloroform solution and stored.

[0062] (3) Disperse the MOF nanosheet dispersion prepared in step (2) in chloroform, wherein the mass fraction of MOF nanosheets is 1%, and stir for 20 min to ensure full dispersion; then add 10 wt% PI polymer powder while stirring to prevent polymer powder aggregation, and stir the mixed casting solution at room temperature for 24 h to ensure full mixing and dispersion; ultrasonically treat the stirred casting solution for 1 h to degas. Finally, spin-coat the treated casting solution to form a film. The spin-coating substrate is α-Al2O3, the spin-coating speed is 8000 rpm, and the spin-coating time is 60 s to allow the solvent to completely evaporate.

[0063] (4) Transfer the membrane from step (3) to a forced-air drying oven for heat treatment at 240°C for 24 hours. During the heat treatment, use a glass plate to press the mixed matrix membrane to prevent the membrane from curling. Then, perform slow annealing at a cooling rate of 3°C / min to prevent defects from forming.

[0064] The decarboxylation mixed matrix membrane constructed based on in-situ thermal induction in this embodiment is applied to gas separation:

[0065] The prepared decarboxylated mixed matrix membrane was sealed with epoxy resin in a permeation cell for gas separation testing. An equimolar mixture of CO2 / N2 or CO2 / CH4 was injected into the shell side of the mixed matrix membrane for gas permeation. A 1:1 mixed gas was added to the feed side of the membrane, and the permeate gas was removed from the permeate side using scavenging gas (Ar). The gas separation performance was calculated after detection using an Agilent gas chromatograph 7890A.

[0066] The decarboxylated mixed matrix membrane prepared in this embodiment has a CO2 flux of 100 Barrer and CO2 / N2 or CO2 / CH4 selectivity as high as 102 and 110.6, respectively, indicating that the mixed matrix membrane prepared by this invention has excellent performance and good application prospects.

[0067] Example 5

[0068] Compared with Example 2, the difference is that in step (3), the mass fraction of MOF nanosheets is 0.15%, and then 10 wt% of PI polymer is added.

[0069] The decarboxylated mixed matrix membrane prepared in this embodiment has a CO2 flux of 63.2 Barrer and CO2 / N2 or CO2 / CH4 selectivity as high as 75.6 and 52.3, respectively.

[0070] Example 6

[0071] Compared with Example 2, the difference is that in step (3), the mass fraction of MOF nanosheets is 0.5%, and then 10 wt% of PI polymer is added.

[0072] The decarboxylated mixed matrix membrane prepared in this embodiment has a CO2 flux of 95.6 Barrer and CO2 / N2 or CO2 / CH4 selectivity as high as 124.1 and 100.6, respectively.

[0073] Example 7

[0074] Compared with Example 2, the difference is that in step (3), the mass fraction of MOF nanosheets is 3%, and then 10 wt% of PI polymer is added.

[0075] The decarboxylated mixed matrix membrane prepared in this embodiment has a CO2 flux of 153.6 Barrer and CO2 / N2 or CO2 / CH4 selectivity as high as 230.2 and 200.5, respectively.

[0076] Example 8

[0077] Compared with Example 2, the difference is that in step (3), the mass fraction of MOF nanosheets is 5%, and then 10 wt% of PI polymer is added.

[0078] The decarboxylated mixed matrix membrane prepared in this embodiment has a CO2 flux of 186.9 Barrer and CO2 / N2 or CO2 / CH4 selectivity as high as 138.9 and 123.6, respectively.

[0079] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for constructing a decarboxylation mixed matrix membrane based on in-situ thermal induction, characterized in that, Includes the following steps: The carboxylic acid ligand and the metal salt were dissolved and mixed to obtain a MOF precursor solution; the MOF precursor solution was heat-treated to obtain MOF nanosheets; the MOF nanosheets were blended with the polymer in a solvent to prepare a casting solution; a mixed matrix membrane was prepared using the casting solution; finally, the mixed matrix membrane was decarboxylated by treating it at 230-250℃ for 1-36 h, and after cooling, a decarboxylated mixed matrix membrane was obtained. The molar ratio of the carboxylic acid ligand to the metal salt is 1–55:1; the concentration of the metal ion in the MOF precursor solution is 0.5–50.8 mmol·L⁻¹. -1 ; The carboxylic acid ligand is 2,5-dibromoterephthalic acid, 2,5-dihydroxyterephthalic acid, or terephthalic acid; the metal salt is a divalent or trivalent metal salt. The heat treatment temperature is 30–100°C, and the time is 1–100 min.

2. The method for constructing a decarboxylation mixed matrix membrane based on in-situ thermal induction according to claim 1, characterized in that, The heat treatment method is microwave heating.

3. The method for constructing a decarboxylation mixed matrix membrane based on in-situ thermal induction according to claim 1, characterized in that, The MOF nanosheets also include a cleaning step before the casting solution is prepared.

4. The method for constructing a decarboxylation mixed matrix membrane based on in-situ thermal induction according to claim 1, characterized in that, The polymer is selected from polysulfone, polyimide, polyethylene oxide, microporous polymer or polyvinylidene fluoride; the solvent of the casting solution is N,N-dimethylformamide, chloroform, dichloromethane or methanol; the mass fraction of MOF nanosheets in the casting solution is 0.1-30%, and the mass fraction of polymer is 1-40%.

5. The method for constructing a decarboxylation mixed matrix membrane based on in-situ thermal induction according to claim 1, characterized in that, The cooling rate shall not exceed 5°C / min.

6. A decarboxylation mixed matrix membrane prepared by the method of in-situ thermally induced construction of a decarboxylation mixed matrix membrane according to any one of claims 1 to 5.

7. The application of the decarboxylation mixed matrix membrane of claim 6 in gas separation.

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