A plasma-modified metal-organic framework / polyimide hybrid matrix membrane, its preparation method and application

Abstract

This invention belongs to the field of gas separation and discloses a plasma-modified metal-organic framework / polyimide hybrid matrix membrane, its preparation method, and its application. The preparation method involves dissolving pyrazine and zinc fluorosilicate separately in methanol to form solutions; adding the pyrazine methanol solution to the zinc fluorosilicate methanol solution; collecting the solid by centrifugation after the reaction, vacuum drying, and grinding to obtain metal-organic framework nanomaterials; and then subjecting the metal-organic framework nanomaterials to plasma modification. A polyimide membrane matrix is ​​obtained by reacting dianhydride and diamine as monomer raw materials. The plasma-modified metal-organic framework nanomaterials are added to the polyimide solution to obtain a casting solution, and the hybrid matrix membrane is prepared by solvent evaporation. The hybrid matrix membrane prepared by this method improves the interfacial compatibility between organic and inorganic materials; reduces the crystallinity of the polymer; and effectively enhances the gas permeation and separation performance.

Description

Technical Field

[0001] This invention relates to the field of gas separation, and more particularly to a plasma-modified metal-organic framework / polyimide hybrid matrix membrane, its preparation method, and its application. Background Technology

[0002] In the field of gas membrane separation, polymeric membranes are the most important separation layer materials for industrial applications, offering advantages such as readily available raw materials and ease of large-scale processing. Conventional polymeric materials include polyimides, polysulfones, polyethersulfones, polyacrylonitrile, polyvinylidene fluoride, and aromatic polyamides. However, traditional polymeric materials, due to their trade-off effect, struggle to simultaneously achieve high permeation rates and selectivity. Hybrid matrix membrane materials are considered an effective solution to this problem, offering advantages such as ease of processing, low cost, high mechanical properties, and thermal stability, making them a promising gas separation membrane material for various applications.

[0003] Incorporating inorganic nanomaterials into organic phases to construct hybrid matrix membranes, thereby adjusting the membrane's porous structure and permeation selectivity, is of practical significance. Hybrid matrix membranes combine the advantages of inorganic nanomaterials and organic continuous phase matrices, effectively enhancing permeation rates while retaining gas selectivity. However, the preparation of hybrid matrix membranes often faces the challenge of interfacial compatibility between organic and inorganic materials, leading to the tendency of doped nanomaterials to aggregate, reducing the overall separation performance of the hybrid matrix membrane and limiting its applications. Summary of the Invention

[0004] This invention addresses the problems of insufficient organic-inorganic interface compatibility and easy agglomeration of nanomaterials during the preparation of hybrid matrix membranes using metal-organic framework nanomaterials. It provides a plasma-modified metal-organic framework / polyimide hybrid matrix membrane, its preparation method, and its applications.

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

[0006] A method for preparing a plasma-modified metal-organic framework / polyimide hybrid matrix film includes the following steps:

[0007] Pyrazine and zinc fluorosilicate were dissolved in methanol to form solutions, and the methanol solution of pyrazine was added to the methanol solution of zinc fluorosilicate.

[0008] The solution after the reaction was centrifuged, the collected solid was washed multiple times with methanol, vacuum dried, and ground to obtain metal-organic framework nanomaterials.

[0009] Metal-organic framework nanomaterials were placed in a preset gas source, the plasma frequency was set to 13.56MHz, the voltage was gradually increased, and after a preset time, plasma-modified metal-organic framework nanomaterials were obtained.

[0010] A polyamic acid solution was prepared using dianhydride and diamine as monomer raw materials, and a polyimide membrane matrix was obtained by catalysis and dehydration.

[0011] A polyimide solution was prepared using a polyimide membrane matrix. Plasma-modified metal-organic framework nanomaterials were added to the polyimide solution to obtain a casting solution. The casting solution was poured onto a glass plate, dried, and cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide hybrid matrix membrane.

[0012] The preset gas source is Ar / O2 or Ar / NH3·H2O.

[0013] The preset time for plasma treatment is 3 to 12 minutes.

[0014] The dianhydride is any one of pyromellitic dianhydride, 4,4'-(hexafluoroisopropene) dianhydride, 4,4'-biphenyl ether dianhydride, bisphenol dianhydride, biphenyltetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and fluorenyl dianhydride.

[0015] The diamine is any one of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4-diaminodiphenylmethane, 4,4-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, 2,3,5,6-tetramethyl-1,4-phenylenediamine, 1,3,5-tris(4-aminophenoxy)benzene, 2,3,5,6-tetrafluoro-1,4-phenylenediamine, and 2,4,6-trimethyl-1,3-phenylenediamine.

[0016] The solid content of the polyimide solution is 11 wt%.

[0017] The doping content of the plasma-modified metal-organic framework nanomaterials in the casting solution is 0-20%.

[0018] The dehydrating agent used in the preparation of the polyimide membrane matrix is ​​acetic anhydride, and the catalyst used is triethylamine.

[0019] The hybrid matrix membrane prepared by the above-mentioned plasma-modified metal-organic framework / polyimide hybrid matrix membrane forms hydrogen bonds or crosslinks between the plasma-modified metal-organic framework nanomaterials and the polyimide.

[0020] The plasma-modified metal-organic framework / polyimide hybrid matrix membrane prepared above is used in gas separation.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention provides a plasma-modified metal-organic framework / polyimide hybrid matrix membrane, its preparation method, and its applications. The method is simple and easy to implement. Plasma-modified metal-organic framework nanomaterials are added to a polyimide matrix for doping, forming hydrogen bonds or crosslinks. This solves the problem of nanomaterial agglomeration during doping and overcomes the difficulty of simultaneously improving the permeation rate and selectivity of organic polymer materials in gas separation. The prepared plasma-modified metal-organic framework / polyimide hybrid matrix membrane, with the addition of plasma-modified metal-organic framework nanomaterials, improves the interfacial compatibility between organic and inorganic materials, reduces the crystallinity of the polymer, and effectively enhances gas separation performance. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below:

[0024] Figure 1 FTIR spectra of the nanomaterials prepared in Comparative Example 2 of the present invention, and the plasma-modified nanomaterials prepared in Examples 10 and 13 of the present invention.

[0025] Figure 2 The FTIR spectra of the polyimide film prepared in Comparative Example 1 of the present invention, and the mixed matrix films prepared in Comparative Example 2, Example 10 and Example 13 are shown.

[0026] Figure 3 TGA images of the nanomaterials prepared in Comparative Example 2 of the present invention, and the plasma-modified nanomaterials prepared in Examples 10 and 13 of the present invention.

[0027] Figure 4 TGA images of the polyimide film prepared in Comparative Example 1 of the present invention, and the mixed matrix films prepared in Comparative Example 2, Example 10 and Example 13;

[0028] Figure 5 XRD patterns of the polyimide film prepared in Comparative Example 1 of the present invention, and the mixed matrix films prepared in Comparative Example 2, Example 10 and Example 13.

[0029] Figure 6In the image, (a1), (a2), (a3), and (a4) are SEM images of the surface of the films prepared in Comparative Example 1, Comparative Example 2, Example 10, and Example 13 of the present invention, respectively; (b1), (b2), (b3), and (b4) are SEM images of the cross-section of the films prepared in Comparative Example 1, Comparative Example 2, Example 10, and Example 13 of the present invention, respectively. Detailed Implementation

[0030] The present invention will be further described below with reference to the embodiments.

[0031] This invention provides a method for preparing a plasma-modified metal-organic framework / polyimide hybrid matrix film, specifically including the following steps:

[0032] Preparation of metal-organic framework nanomaterials: Pyrazine and zinc fluorosilicate (ZnSiF6) were dissolved in methanol to form homogeneous solutions. Under the combined action of ultrasound and ice bath, the methanol solution of pyrazine was added dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials. The reaction solution was centrifuged, the collected solid was washed with methanol multiple times, vacuum dried, and ground to obtain metal-organic framework nanomaterials.

[0033] Preparation of plasma-modified metal-organic framework nanomaterials: Metal-organic framework nanomaterials are placed in a circular chamber, and a preset gas source is introduced to replace the gas in the original chamber. The plasma frequency is set to 13.56MHz, the voltage is gradually increased, and the process is carried out for a certain period of time to obtain plasma-modified metal-organic framework nanomaterials.

[0034] Synthesis of polyimide membrane matrix: Polyamic acid solution was prepared using dianhydride and diamine as monomer raw materials, and polyimide membrane matrix was synthesized by catalysis and dehydration.

[0035] Preparation of hybrid matrix membrane: A polyimide solution was prepared using a polyimide membrane matrix. Plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The hybrid matrix membrane was prepared by solvent evaporation. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide hybrid matrix membrane.

[0036] Furthermore, the dianhydride used to prepare the polyimide is any one of pyromellitic dianhydride, 4,4'-(hexafluoroisopropene) phthalic anhydride, 4,4'-biphenyl ether dianhydride, bisphenol dianhydride, biphenyltetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and fluorenyl dianhydride.

[0037] Furthermore, the diamine used to prepare the polyimide is any one of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4-diaminodiphenylmethane, 4,4-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, 2,3,5,6-tetramethyl-1,4-phenylenediamine, 1,3,5-tris(4-aminophenoxy)benzene, 2,3,5,6-tetrafluoro-1,4-phenylenediamine, and 2,4,6-trimethyl-1,3-phenylenediamine.

[0038] Furthermore, the dehydrating agent used in the preparation of the polyimide membrane matrix is ​​acetic anhydride, and the catalyst used for catalysis is triethylamine.

[0039] Furthermore, the plasma-modified gas source contains Ar / O2 or Ar / NH3·H2O.

[0040] Furthermore, the plasma treatment time is 3 to 12 minutes.

[0041] Furthermore, the solid content of the polyimide solution is 11 wt%, and the doping content of the plasma-modified metal-organic framework nanomaterials in the casting solution is 0-20%.

[0042] Example 1

[0043] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0044] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / O2 gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 3 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0045] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0046] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 5% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0047] Example 2

[0048] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0049] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / O2 gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 6 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0050] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0051] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 5% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0052] Example 3

[0053] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0054] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / O2 gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 9 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0055] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0056] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 5% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0057] Example 4

[0058] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0059] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / O2 gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 12 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0060] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0061] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 5% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0062] Example 5

[0063] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0064] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / NH3·H2O gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 3 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0065] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0066] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 5% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0067] Example 6

[0068] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0069] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / NH3·H2O gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 6 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0070] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0071] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 5% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0072] Example 7

[0073] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0074] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / NH3·H2O gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 9 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0075] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0076] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 5% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0077] Example 8

[0078] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0079] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / NH3·H2O gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 12 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0080] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0081] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 5% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0082] Example 9

[0083] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0084] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / O2 gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 9 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0085] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0086] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 10% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0087] Example 10

[0088] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0089] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / O2 gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 9 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0090] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0091] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 15% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0092] Example 11

[0093] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0094] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / O2 gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 9 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0095] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0096] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 20% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0097] Example 12

[0098] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0099] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / NH3·H2O gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 9 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0100] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0101] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 10% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0102] Example 13

[0103] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0104] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / NH3·H2O gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 9 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0105] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0106] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 15% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0107] Example 14

[0108] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0109] (2) The metal-organic framework nanomaterials were placed in a circular chamber, and Ar / NH3·H2O gas source was introduced to replace the gas in the original chamber. The plasma frequency was set to 13.56MHz, the voltage was gradually increased, and the treatment was carried out for 9 minutes to obtain plasma-modified metal-organic framework nanomaterials.

[0110] (3) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene) phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0111] (4) A polyimide solution was prepared using a polyimide membrane matrix. The solid content of the polyimide solution was 11 wt%. 20% of plasma-modified metal-organic framework nanomaterials were added to the polyimide solution and ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a plasma-modified metal-organic framework / polyimide mixed matrix membrane.

[0112] In Examples 1-14, the dianhydride used to prepare polyimide can also be any one of pyromellitic dianhydride, 4,4'-biphenyl ether dianhydride, bisphenol dianhydride, biphenyltetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, and fluorenyl dianhydride, which has the same effect as 4,4'-(hexafluoroisopropene) phthalic anhydride.

[0113] The diamine used to prepare polyimide in Examples 1-14 can also be any one of 4,4-diaminodiphenylmethane, 4,4-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, 2,3,5,6-tetramethyl-1,4-phenylenediamine, 1,3,5-tris(4-aminophenoxy)benzene, 2,3,5,6-tetrafluoro-1,4-phenylenediamine, and 2,4,6-trimethyl-1,3-phenylenediamine, which has the same effect as 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane.

[0114] Comparative Example 1

[0115] (1) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene)phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by triethylamine catalysis and acetic anhydride dehydration.

[0116] (2) Dissolve the polyimide matrix to obtain a casting solution with a solid content of 11 wt%. Pour the casting solution onto a glass plate and place it in a vacuum drying oven. After drying for 24 hours, allow it to cool naturally to room temperature to obtain a polyimide film.

[0117] Comparative Example 2

[0118] (1) Dissolve 0.3g pyrazine and 0.38g ZnSiF6 in 6ml of methanol to form a homogeneous solution; under the combined action of ultrasound and ice bath, add the methanol solution of pyrazine dropwise to the methanol solution of ZnSiF6 to synthesize nanomaterials; centrifuge the solution after reaction, wash the collected solid with methanol multiple times, vacuum dry, grind, and obtain metal-organic framework nanomaterials.

[0119] (2) A polyamic acid solution was prepared using 4,4'-(hexafluoroisopropene)phthalic anhydride and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane as monomer raw materials, and a polyimide membrane matrix was synthesized by catalysis with triethylamine and dehydration with acetic anhydride.

[0120] (3) 15% of unmodified metal-organic framework nanomaterials were added to a polyimide solution with a solid content of 11 wt%. The solution was ultrasonically stirred to obtain a casting solution. The casting solution was poured onto a glass plate and placed in a vacuum drying oven. After drying for 24 hours, it was naturally cooled to room temperature to obtain a metal-organic framework / polyimide mixed matrix membrane.

[0121] The separation performance of the prepared membrane was tested using a permeation testing evaluation device. The test structure is shown below:

[0122] Figure 1 The images show the FTIR spectra of the nanomaterials prepared in Comparative Example 2, and the plasma-modified nanomaterials prepared in Examples 10 and 13 of this invention. As can be seen from the figures, the absorption peaks are in the range of 3200–3400 cm⁻¹. -1 The band at 1630 cm⁻¹ is the stretching vibration of -OH. -1 and 1335cm -1 The band at that location represents the vibration of the triazine ring. Compared to the nanomaterials prepared in Comparative Example 2, the plasma-modified nanomaterials prepared in Example 10 exhibit vibrations at 3200–3500 cm⁻¹. -1 and 1335cm -1 The broadening of the absorption band at 3320 cm⁻¹ indicates the presence of more -OH stretching vibrations. The plasma-modified nanomaterials prepared in Example 13 showed increased absorption band at 3320 cm⁻¹. -1 The characteristic absorption peak appears at the point, which is due to the formation of amino groups on the surface of the nanomaterial.

[0123] Figure 2 The images show the FTIR spectra of the polyimide film prepared in Comparative Example 1, and the mixed matrix films prepared in Comparative Examples 2, 10, and 13 of this invention. As can be seen from the figures, the absorption peak is at 1780 cm⁻¹. -1 The characteristic band at this location is the asymmetric vibration of C=O (amide I band), 1720 cm⁻¹. -1The absorption is a C=O symmetric vibration (amide II band), 1500 cm⁻¹. -1 The absorption band at this point represents the skeletal stretching vibration of the aromatic ring. 1369cm -1 The peak at 718 cm⁻¹ represents the CN stretching vibration (amide III band) in the imide ring. -1 The peak at this location corresponds to the bending vibration of the imide ring (amide IV band). Compared to the polyimide film prepared in Comparative Example 1, the addition of nanomaterials interacts with the polymer matrix. Plasma-modified metal-organic framework nanomaterials are incorporated into the polyimide matrix for doping, forming hydrogen bonds or crosslinks. For example, the infrared absorption peak is in the range of 3200–3400 cm⁻¹. -1 The absorption peak at position 1100 cm⁻¹ is enhanced, and at the same time, the absorption peak at position 1100 cm⁻¹ is enhanced. -1 The absorption peak shifts to lower wavenumbers, indicating that hydrogen bonds are formed between the nanomaterial and the polymer. The interaction of these hydrogen bonds will increase the affinity between the nanomaterial and the polymer, thereby achieving better interfacial compatibility.

[0124] Figure 3 The TGA graphs show the nanomaterials prepared in Comparative Example 2, and the plasma-modified nanomaterials prepared in Examples 10 and 13 of this invention. As can be seen from the graphs, the characteristic decomposition temperatures (90% by weight) of the various nanomaterials are 162°C, 157°C, and 154°C, respectively. Since the separation temperature for CO2 capture is typically less than 100°C, these nanomaterials can meet the temperature requirements for gas separation.

[0125] Figure 4 The TGA graphs show the polyimide membrane prepared in Comparative Example 1, and the mixed matrix membranes prepared in Comparative Example 2, Example 10, and Example 13 of this invention. As can be seen from the graphs, compared to Example 1, the membrane material with added nanomaterials still meets the temperature requirements for gas separation.

[0126] Figure 5 The figures show the XRD patterns of the polyimide film prepared in Comparative Example 1, and the mixed matrix films prepared in Comparative Examples 2, 10, and 13. As can be seen from the figures, the film materials prepared in this invention all exhibit amorphous diffraction peaks. The polyimide film prepared in Comparative Example 1 has only one diffraction peak at 2θ–16°, with an average interchain spacing of [missing value]. Compared to Comparative Example 1, the diffraction peak intensities of the polymers in the mixed matrix membranes prepared in Comparative Example 2, Example 10, and Example 13 decreased after the addition of nanomaterials. This is because the addition of nanomaterials effectively breaks up the stacking of polymer chain segments, leading to a decrease in crystallinity and facilitating gas permeation. Furthermore, compared to mixed matrix membranes with nanomaterials modified by different gas source plasmas, the mixed matrix membrane with Ar / NH3·H2O gas source plasma-modified metal-organic framework nanomaterials exhibited the best permeation separation performance, followed by the mixed matrix membrane with Ar / O2 gas source plasma-modified metal-organic framework nanomaterials and the mixed matrix membrane with unmodified nanomaterials. This indicates that adding plasma-modified metal-organic framework nanomaterials to a polyimide matrix can effectively enhance gas permeation separation performance.

[0127] Figure 6 In Figures (a1), (a2), (a3), and (a4), SEM images of the surfaces of the films prepared in Comparative Examples 1, 2, 10, and 13 of this invention are shown, respectively; in Figures (b1), (b2), (b3), and (b4), SEM images of the cross-sections of the films prepared in Comparative Examples 1, 2, 10, and 13 of this invention are shown, respectively. As can be seen from the figures, the prepared films exhibit a smooth, dense, and defect-free morphology. Furthermore, comparing the three types of nanoparticles in Comparative Examples 2, 10, and 13, it is evident that the mixed matrix film prepared with Ar / NH3·H2O gas source plasma-modified metal-organic framework nanomaterials exhibits the best dispersion performance. This indicates that the plasma-modified metal-organic framework nanomaterials prepared in this invention enhance the compatibility of the organic and inorganic interfaces and can be effectively dispersed in the polymer matrix.

[0128] The plasma-modified metal-organic framework / polyimide hybrid matrix membrane prepared in this invention is used in gas separation.

[0129] As shown in Table 1, the membranes prepared in Examples 1-14, Comparative Example 1, and Comparative Example 2 of the present invention were used to separate CO2 / N2 and CO2 / CH4. It can be seen from the table that the mixed matrix membrane prepared by adding Ar / NH3·H2O gas source plasma-modified metal-organic framework nanomaterials has good CO2 permeability and selectivity. In particular, under the experimental conditions of Example 13, the performance of the plasma-modified metal-organic framework nanomaterial-doped polyimide mixed matrix membrane is the best.

[0130] Table 1 shows the permeation rate and selectivity tests of the membranes prepared in Examples 1-14, Comparative Examples 1 and 2 for CO2 / N2 and CO2 / CH4 separation.

[0131]

[0132] Unit: 1 Barrer = 10 -10 cm 3 (STP)·cm / (cm 2 ·s·cmHg)

[0133] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention pending approval.

Claims

1. A method for preparing a plasma-modified metal-organic framework / polyimide hybrid matrix membrane, characterized by, The method comprises the following steps: pyrazine and zinc fluorosilicate are dissolved in methanol to form solutions respectively; the methanol solution of pyrazine is added into the methanol solution of zinc fluorosilicate; the reacted solution is centrifuged, the collected solid is washed with methanol for multiple times, vacuum dried, and ground to obtain a metal organic framework nanomaterial; the metal organic framework nanomaterial is placed in a preset gas source, the plasma frequency is set to 13.56 MHz, the voltage is gradually increased, and the plasma modified metal organic framework nanomaterial is obtained after a preset time of treatment; polyamic acid solution is prepared by using dianhydride and diamine as monomer raw materials, and polyimide film matrix is obtained through catalysis and dehydration; the plasma modified metal organic framework nanomaterial is added into the polyimide solution to obtain a casting solution, the casting solution is poured on a glass plate, dried, and cooled to room temperature to obtain a plasma modified metal organic framework / polyimide hybrid matrix film.

2. The method of claim 1, wherein the metal-organic framework / polyimide hybrid matrix membrane is prepared by the steps of: (a) preparing a solution of a metal-organic framework and a polyimide; (b) coating the solution on a substrate; (c) drying the coated solution; and (d) calcining the coated solution. The preset gas source is Ar / O2 or Ar / NH3·H2O.

3. The method of claim 1, wherein the metal-organic framework / polyimide hybrid matrix membrane is prepared by the steps of: (a) preparing a solution of a metal-organic framework and a polyimide; (b) coating the solution on a substrate; (c) drying the coated solution; and (d) calcining the coated solution. The preset time of the plasma treatment is 3-12 min.

4. The method of claim 1, wherein the metal-organic framework / polyimide hybrid matrix membrane is prepared by the steps of: (a) preparing a solution of a metal-organic framework and a polyimide; (b) coating the solution on a substrate; (c) drying the coated solution; and (d) calcining the coated solution. The dianhydride is any one of pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 4,4'-diphenyl ether dianhydride, bisphenol dianhydride, biphenyl tetracarboxylic dianhydride, 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and fluorenyl dianhydride.

5. The method of claim 1, wherein the metal-organic framework / polyimide hybrid matrix membrane is prepared by the steps of: (a) preparing a solution of a metal-organic framework and a polyimide; (b) coating the solution on a substrate; (c) drying the coated solution; and (d) calcining the coated solution. The diamine is any one of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane / 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4-diaminodiphenyl methane, 4,4-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, 2,3,5,6-tetramethyl-1,4-benzenediamine, 1,3,5-tris(4-aminophenoxy)benzene, 2,3,5,6-tetrafluoro-1,4-benzenediamine, and 2,4,6-trimethyl-1,3-benzenediamine.

6. The method for preparing a plasma-modified metal-organic framework / polyimide hybrid matrix film according to claim 1, characterized in that, The solid content of the polyimide solution is 11 wt%.

7. The method for preparing a plasma-modified metal-organic framework / polyimide hybrid matrix film according to claim 1, characterized in that, The doping content of the plasma modified metal organic framework nanomaterial in the casting solution is 0-20%.

8. The method for preparing a plasma-modified metal-organic framework / polyimide hybrid matrix membrane according to claim 1, characterized in that, The dehydrating agent used in the dehydration in the preparation of the polyimide film matrix is acetic anhydride, and the catalyst used in the catalysis is triethylamine.

9. The mixed matrix membrane prepared according to the method of any one of claims 1-8, wherein the mixed matrix membrane is characterized by, Hydrogen bonds or cross-linking are formed between the plasma modified metal organic framework nanomaterial and the polyimide.

10. The plasma modified metal organic framework / polyimide hybrid matrix film according to claim 9 is applied in gas separation.

Images