阅读说明：本技术 一种应用于co2分离的聚酰亚胺混合基质膜及其制备方法 (Application to CO2Separated polyimide mixed matrix membrane and preparation method thereof ) 是由 王小红 于 2021-08-02 设计创作，主要内容包括：本发明具体公开了一种应用于CO2分离的聚酰亚胺混合基质膜及其制备方法。首先制备溴改性的锆金属有机框架,对聚乙二醇进行改性,得到一端是羟基、另一端为氨基的聚乙二醇,同时以3,5-二氨基苯甲酸、均苯四甲酸二酐和4,4’-二氨基二苯醚为单体,制备侧链含羧基聚酰胺酸前驱体,在通过亚胺化反应得到了侧链含羧基聚酰亚胺；最后以聚乙二醇为桥梁,一端和锆金属有机框架通过取代反应连接,另一端通过缩合反应和和侧链含羧基聚酰亚胺连接,得到一种聚酰亚胺混合基质膜。本发明解决了金属有机框架和聚酰亚胺层间存在明显的非选择性空隙的问题,提高了锆金属有机框架在基膜中的分散性,增强了膜对CO-(2)的分离。(The invention particularly discloses a polyimide mixed matrix membrane applied to CO2 separation and a preparation method thereof. Firstly, preparing a bromine-modified zirconium metal organic framework, modifying polyethylene glycol to obtain polyethylene glycol with one end being hydroxyl and the other end being amino, simultaneously preparing a polyamic acid precursor with a side chain containing carboxyl by using 3, 5-diaminobenzoic acid, pyromellitic dianhydride and 4, 4' -diaminodiphenyl ether as monomers, and obtaining polyimide with a side chain containing carboxyl through imidization reaction; finally, taking polyethylene glycol as a bridge, and taking one end of the polyethylene glycol and the zirconium metal organic framework through a filterAnd the other end is connected with polyimide containing carboxyl on the side chain through condensation reaction to obtain the polyimide mixed matrix membrane. The invention solves the problem that obvious non-selective gaps exist between the metal organic framework and the polyimide layer, improves the dispersibility of the zirconium metal organic framework in the base film, and enhances the CO pairing performance of the film 2 Separation of (4).)

1. Application to CO₂A method for preparing a separated polyimide mixed matrix membrane, comprising the steps of:

(a) preparation of bromine-modified zirconium metal organic framework:

mixing zirconium chloride, 2-bromoterephthalic acid and dimethylformamide, and carrying out ultrasonic treatment to ensure that all reactants are completely dissolved to obtain a mixture; pouring terephthalic acid and dimethylformamide into the mixture, carrying out ultrasonic treatment, standing after ultrasonic treatment, washing precipitated particles with dimethylformamide and methanol, centrifuging to remove unreacted impurities, and drying overnight at 60 ℃ under vacuum to obtain a bromine-modified zirconium metal organic framework;

(b) preparation of polyethylene glycol grafted zirconium Metal organic framework

(b1) Dissolving polyethylene glycol, catalyst silver oxide and potassium iodide in dichloromethane, adding p-toluenesulfonyl chloride, magnetically stirring at room temperature for 2-3h, and filtering to obtain a product A; dissolving the product A in concentrated ammonia water (25% -28%), adding ammonium chloride, magnetically stirring at room temperature for three days, extracting with dichloromethane, and evaporating to remove the solvent to obtain polyethylene glycol (HO-PEG-NH2) with one hydroxyl end and one amino end;

(b2) ultrasonically dispersing a bromine-modified zirconium metal organic framework in an ethanol solvent, adding HO-PEG-NH2, uniformly stirring, performing substitution reaction in a nitrogen atmosphere, filtering after the reaction is finished, washing with acetone, and drying to obtain a polyethylene glycol grafted zirconium metal organic framework;

(c) preparation of modified polyimide

(c1) Adding 3, 5-diaminobenzoic acid, 4, 4' -diaminodiphenyl ether and dimethylacetamide into a reaction bottle in a nitrogen atmosphere, uniformly stirring, adding a dimethylacetamide solution containing pyromellitic dianhydride into the mixed solution, carrying out synthetic reaction, and obtaining a polyamic acid precursor with carboxyl on the side chain after the reaction is finished;

(c2) dissolving a polyamic acid precursor with a side chain containing carboxyl in dimethylacetamide, diluting into a solution with the mass fraction of 3-8%, carrying out imidization reaction, washing with ethanol after the reaction is finished, and drying to obtain polyimide with a side chain containing carboxyl;

(d) preparation of polyimide Mixed matrix Membrane

(d1) Dissolving polyimide with a side chain containing carboxyl in anhydrous N, N-dimethylformamide, adding a polyethylene glycol grafted zirconium metal organic framework after uniform ultrasonic dispersion, reacting under a heating and stirring condition, centrifuging after the reaction is finished, and washing to obtain a zirconium metal organic framework-polyethylene glycol grafted polyimide composite material;

(d2) the zirconium metal organic framework-polyethylene glycol grafted polyimide composite materialDissolving in dimethylacetamide solvent, ultrasonic treating for 1-3 hr, pouring the suspension onto glass mold, evaporating, and drying to obtain the final product for CO₂An isolated polyimide mixed matrix membrane.

2. The catalyst is applied to CO according to claim 1₂The preparation method of the separated polyimide mixed matrix membrane is characterized in that the mass ratio of zirconium chloride, 2-bromoterephthalic acid and dimethylformamide in the mixture in the step (a) is 1:1-2: 50-60; the mass ratio of the phthalic acid to the dimethylformamide added in the step (a) is 1: 1-100.

3. The catalyst is applied to CO according to claim 1₂The preparation method of the separated polyimide mixed matrix membrane is characterized in that the ultrasonic treatment time of the mixture in the step (a) is 20-120min, and the standing condition after ultrasonic treatment is 70-80 ℃ for heating and standing for 12-24 hours.

4. The catalyst is applied to CO according to claim 1₂The preparation method of the separated polyimide mixed matrix membrane is characterized in that in the step (b1), the mass ratio of polyethylene glycol to p-toluenesulfonyl chloride to silver oxide to potassium iodide is 10: 1-1.5: 1-2: 1-1.5; the mass ratio of the product A to the ammonium chloride in the step (b1) is 1: 2-4.

5. The catalyst is applied to CO according to claim 1₂A method for preparing a separated polyimide mixed matrix membrane, wherein the mass ratio between the bromine-modified zirconium metal organic framework and HO-PEG-NH2 in the step (b2) is 10: 50-100; the reaction temperature of the grafting reaction in the step (b2) is 10-30 ℃, and the reaction time is 1-5 h.

6. The catalyst is applied to CO according to claim 1₂The method for preparing the separated polyimide mixed matrix membrane, wherein 3, 5-diaminobenzoic acid, 4, 4' -diaminodiphenyl ether and pyromellitic dianhydride in the step (c1)The mass ratio of the acid dianhydride is 8-20:60-80:100, the reaction temperature of the synthesis reaction is 10-30 ℃, and the reaction time is 18-36 h.

7. The catalyst is applied to CO according to claim 1₂The preparation method of the separated polyimide mixed matrix membrane is characterized in that the reaction temperature of the imidization reaction in the step (c2) is 90-200 ℃, and the reaction time is 18-36 h.

8. The catalyst is applied to CO according to claim 1₂The preparation method of the separated polyimide mixed matrix membrane is characterized in that in the step (d1), the mass ratio of the polyethylene glycol grafted zirconium metal organic framework to the polyimide with side chains containing carboxyl is 1:10-100, and the heating and stirring reaction conditions are 50-100 ℃ for reaction for 3-6 h.

9. The catalyst is applied to CO according to claim 1₂The preparation method of the separated polyimide mixed matrix membrane is characterized in that the evaporation process condition in the step (d2) is that the evaporation process is carried out for 12-24h at the temperature of 40-60 ℃, and the drying condition is that the drying treatment is carried out for 12-28h at the temperature of 80-120 ℃.

10. A polyimide mixed matrix membrane for CO2 separation, which is produced by the production method according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of membrane separation, in particular to a membrane separation device applied to CO₂An isolated polyimide mixed matrix membrane and a method of making the same.

Background

Carbon dioxide (CO)₂) Is an important industrial raw material and is the main cause of global warming, so that CO is used as a raw material for the industrial production₂Is trapped inThe use and environmental protection level has great significance. Compared with the traditional technology, the membrane method CO₂The trapping technology has the advantages of simple equipment, small environmental pollution and the like, and is recognized as one of the technologies with the most development prospects in the middle of the 20 th century to the 21 st century.

Polyimides are a family of glassy polymers synthesized by polymerization of various diamine and dianhydride monomers. In recent years, polyimide has been used for its excellent CO₂The membrane material for gas separation has high separation performance, high chemical resistance, excellent thermal stability and mechanical strength, and can be used for preparing a membrane material with outstanding performance for gas separation by utilizing the acid-base affinity action between functional monomers of amine groups and acid gas. However, the existing polyimide materials have insufficient gas permeability, and are often required to be modified to better meet the requirements of practical applications.

Chinese patent CN111111464A discloses a structural design and a preparation method of a super-high carbon dioxide gas selective separation composite membrane, wherein the structural design is as follows, an electrostatic spinning Polyacrylonitrile (PAN) fiber thin film layer and a cyclodextrin metal organic framework Material (MOF) polymer layer with high gas selectivity are adopted, and the preparation method is a two-step rotary coating method and comprises the following steps of preparation of MOF crystals, preparation of a PAN electrostatic spinning membrane, preparation of a selective separation composite membrane, solvent removal and vacuum drying. The film is structurally designed into a three-layer composite film, the PAN fiber film is used as a matrix layer as a mechanical support layer, the porous MOF layer has gas selective permeability, the polymer layer enables the composite film to have good mechanical property, and CO is absorbed by the polymer layer₂/N₂、CO₂/O₂Ultra high CO in iso-gas separation₂Selectivity and higher CO₂Permeability coefficient, sufficient capacity to separate, capture and purify CO₂Has great potential in the aspects of alleviating greenhouse effect and reducing air pollution. However, there are significant non-selective voids between the metal organic framework and the polymer layer, which will lead to CO₂The selectivity decreases.

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides a method for applyingCO₂The separated polyimide mixed matrix membrane and the preparation method thereof solve the problem that obvious non-selective gaps exist between a metal organic framework and a polymer layer to cause CO₂The problem of a decrease in selectivity.

(II) technical scheme

In order to solve the above problems, the present invention proposes the following technical solutions:

application to CO₂An isolated polyimide mixed matrix membrane prepared as follows:

(a) preparation of bromine-modified zirconium metal organic framework:

mixing zirconium chloride, 2-bromoterephthalic acid and dimethylformamide, and carrying out ultrasonic treatment to ensure that all reactants are completely dissolved to obtain a mixture; and pouring terephthalic acid and dimethylformamide into the mixture, carrying out ultrasonic treatment, standing after ultrasonic treatment, washing precipitated particles by using dimethylformamide and methanol, centrifuging to remove unreacted impurities, and drying overnight at 60 ℃ under vacuum to obtain the bromine-modified zirconium metal organic framework.

(b) Preparation of polyethylene glycol grafted zirconium Metal organic framework

(b1) Dissolving polyethylene glycol, catalyst silver oxide and potassium iodide in dichloromethane, adding p-toluenesulfonyl chloride, magnetically stirring at room temperature for 2-3h, and filtering to obtain a product A; dissolving the product A in concentrated ammonia water (25-28%), adding ammonium chloride, magnetically stirring at room temperature for three days, extracting with dichloromethane, and evaporating to remove solvent to obtain polyethylene glycol (HO-PEG-NH2) with hydroxyl at one end and amino at the other end.

(b2) Ultrasonically dispersing a bromine-modified zirconium metal organic framework in an ethanol solvent, adding HO-PEG-NH2, uniformly stirring, performing substitution reaction in a nitrogen atmosphere, filtering after the reaction is finished, washing with acetone, and drying to obtain a polyethylene glycol grafted zirconium metal organic framework;

(c) preparation of modified polyimide

(c1) Adding 3, 5-diaminobenzoic acid, 4, 4' -diaminodiphenyl ether and dimethylacetamide into a reaction bottle in a nitrogen atmosphere, uniformly stirring, adding a dimethylacetamide solution containing pyromellitic dianhydride into the mixed solution, carrying out synthetic reaction, and obtaining a polyamic acid precursor with carboxyl on the side chain after the reaction is finished;

(c2) dissolving a polyamic acid precursor with a side chain containing carboxyl in dimethylacetamide, diluting into a solution with the mass fraction of 3-8%, carrying out imidization reaction, washing with ethanol after the reaction is finished, and drying to obtain polyimide with a side chain containing carboxyl;

(d) preparation of polyimide Mixed matrix Membrane

(d1) Dissolving polyimide with a side chain containing carboxyl in anhydrous N, N-dimethylformamide, adding a polyethylene glycol grafted zirconium metal organic framework after uniform ultrasonic dispersion, reacting under a heating and stirring condition, centrifuging after the reaction is finished, and washing to obtain the zirconium metal organic framework-polyethylene glycol grafted polyimide composite material.

(d2) Dissolving a zirconium metal organic framework-polyethylene glycol grafted polyimide composite material in a dimethylacetamide solvent, performing ultrasonic treatment for 1-3 hours, pouring the suspension on a glass mold, evaporating, and drying the film to obtain the composite material applied to CO₂An isolated polyimide mixed matrix membrane.

Preferably, in the step (a), the mass ratio of zirconium chloride, 2-bromoterephthalic acid and dimethylformamide in the mixture is as follows: 1:1-2: 50-60;

preferably, in the step (a), the mass ratio of the added phthalic acid to the added dimethylformamide is as follows: 1: 1-100;

preferably, in the step (a), the ultrasonic treatment time of the mixture is 20-120 min;

preferably, in the step (a), the standing condition after the ultrasonic treatment is as follows: heating and standing at 70-80 deg.C for 12-24 hr;

preferably, in the step (b1), the mass ratio of the polyethylene glycol to the p-toluenesulfonyl chloride to the silver oxide to the potassium iodide is: 10: 1-1.5: 1-2: 1-1.5;

preferably, the mass ratio of the product A to the ammonium chloride in the step (b1) is as follows: 1: 2-4;

preferably, in the step (b2), the mass ratio between the bromine-modified zirconium metal organic framework and HO-PEG-NH2 is 10: 50-100;

preferably, in the step (b2), the reaction temperature of the grafting reaction is 10-30 ℃ and the reaction time is 1-5 h.

Preferably, the mass ratio of the 3, 5-diaminobenzoic acid, 4, 4' -diaminodiphenyl ether and pyromellitic dianhydride in the step (c1) is 8-20:60-80: 100.

Preferably, the reaction temperature of the synthesis reaction in the step (c1) is 10-30 ℃, and the reaction time is 18-36 h.

Preferably, the reaction temperature of the imidization reaction in the step (c2) is 90-200 ℃ and the reaction time is 18-36 h.

Preferably, in the step (d1), the mass ratio of the polyethylene glycol grafted zirconium metal organic framework to the polyimide with side chain containing carboxyl is 1: 10-100;

preferably, in the step (d1), the reaction conditions of heating and stirring are as follows: reacting for 3-6h at 50-100 ℃;

preferably, in the step (d2), the evaporation process conditions are: performing the reaction at 40-60 ℃ for 12-24 h;

preferably, said step (d)2) The drying conditions are: drying at 80-120 deg.C for 12-28 h;

(III) advantageous technical effects

Compared with the prior art, the invention has the following chemical mechanism and beneficial technical effects:

(1) firstly, taking a zirconium metal organic framework as a raw material, and introducing bromine atoms to obtain a bromine-modified zirconium metal organic framework; then modifying the polyethylene glycol to obtain polyethylene glycol with one end being hydroxyl and the other end being amino; then, bromine atoms on the bromine-modified zirconium metal organic framework and hydroxyl on one end of polyethylene glycol are subjected to substitution reaction to obtain polyethylene glycol grafted zirconium metal organic framework, and then amino on the other end of the polyethylene glycol and carboxyl on polyimide with carboxyl on a side chain are subjected to condensation reaction to obtain the polyimide modified zirconium metal organic framework for CO application₂An isolated polyimide mixed matrix membrane.

(2) The invention takes polyethylene glycol as a bridge, and the polyethylene glycol is prepared byOne end of polyethylene glycol is connected with the zirconium metal organic frame through substitution reaction, and the other end of the polyethylene glycol is connected with polyimide with carboxyl on a side chain through condensation reaction, so that an interface structure is established between the polyimide base film and the zirconium metal organic frame, and the problem that an obvious non-selective gap exists between the metal organic frame and a polymer layer is solved. Is more beneficial to the dispersion of the zirconium metal organic framework in the basal membrane, and enhances the CO content of the membrane₂The capture capability of (a).

(3) The rich polar ether group of polyethylene glycol can react with CO₂Produces coupling effect, thereby being capable of carrying out synergistic CO-reaction with a zirconium metal organic framework₂The selection and the capture are carried out, and the CO content is greatly increased₂The absorption capacity of (c); meanwhile, the zirconium metal organic framework is introduced into the membrane, so that the problems of polymer chain hardening and membrane free volume fraction reduction are brought, gas diffusion is not facilitated, and polyethylene glycol can be used as a solubility promoter to soften the membrane, so that the permeability of the membrane is improved.

Detailed Description

To achieve the above object, the present invention provides the following embodiments and examples:

example 1

Application to CO₂An isolated polyimide mixed matrix membrane prepared as follows:

(a) preparation of bromine-modified zirconium Metal organic frameworks

Zirconium chloride (1g), 2-bromoterephthalic acid (2g) and dimethylformamide (50g) were mixed and sonicated for 40 minutes to ensure complete dissolution of all reactants to give a mixture; terephthalic acid (1g) and dimethylformamide (100g) were poured into the above mixture, followed by sonication for 60 minutes, followed by heating at 80 ℃ and standing for 24 hours after sonication, and the precipitated particles were washed with dimethylformamide and methanol and centrifuged to remove unreacted impurities, and dried overnight under vacuum at 60 ℃ to give a bromine-modified zirconium metal organic framework.

(b) Preparation of polyethylene glycol grafted zirconium Metal organic framework

(b1) Dissolving polyethylene glycol (50g), catalyst silver oxide (5g) and potassium iodide (5g) in dichloromethane (100ml), adding p-toluenesulfonyl chloride (6g), magnetically stirring for 2-3h at room temperature, and filtering to obtain a product A; dissolving the product A (50g) in concentrated ammonia water (25-28%), adding ammonium chloride (100g), magnetically stirring at room temperature for three days, extracting with dichloromethane, and evaporating to remove solvent to obtain polyethylene glycol (HO-PEG-NH2) with hydroxyl at one end and amino at the other end.

Ultrasonically dispersing a bromine-modified zirconium metal organic framework (10g) in an ethanol solvent, then adding HO-PEG-NH2(50g), uniformly stirring, carrying out grafting reaction for 5h at 30 ℃ in a nitrogen atmosphere, after the reaction is finished, filtering, washing with acetone, and drying to obtain a polyethylene glycol grafted zirconium metal organic framework;

(c) preparation of modified polyimide

(c1) In the nitrogen atmosphere, 3, 5-diaminobenzoic acid (8g), 4, 4' -diaminodiphenyl ether (40g) and dimethylacetamide are mixed and stirred uniformly, then dimethylacetamide solution containing pyromellitic dianhydride (100g) is added into the mixed solution, synthetic reaction is carried out for 36h at 20 ℃, and after the reaction is finished, a polyamic acid precursor with carboxyl on the side chain is obtained;

(c2) dissolving a polyamic acid precursor with a side chain containing carboxyl in dimethylacetamide, diluting into a solution with the mass fraction of 3-8%, carrying out imidization reaction at 100 ℃ for 12h, washing with ethanol after the reaction is finished, and drying to obtain polyimide with a side chain containing carboxyl;

(d) preparation of polyimide Mixed matrix Membrane

(d1) Dissolving polyimide (50g) with carboxyl on a side chain in anhydrous N, N-dimethylformamide (50ml), adding polyethylene glycol grafted zirconium metal organic framework (2g) after uniform ultrasonic dispersion, reacting under the condition of heating and stirring, centrifuging after the reaction is finished, and washing to obtain the zirconium metal organic framework-polyethylene glycol grafted polyimide composite material.

(d2) Dissolving the zirconium metal organic framework-polyethylene glycol grafted polyimide composite material in a dimethylacetamide solvent (25ml), carrying out ultrasonic treatment for 3 hours, pouring the suspension on a glass mold, evaporating at 60 ℃, carrying out drying treatment for 24 hours at 120 ℃ for the film for 28 hours to obtain the composite materialApplication to CO₂An isolated polyimide mixed matrix membrane.

Example 2

Application to CO₂An isolated polyimide mixed matrix membrane prepared as follows:

(a) preparation of bromine-modified zirconium Metal organic frameworks

Zirconium chloride (1g), 2-bromoterephthalic acid (1g), dimethylformamide (50g) were mixed and sonicated for 40 minutes to ensure complete dissolution of all reactants to give a mixture; terephthalic acid (2g) and dimethylformamide (200g) were poured into the above mixture, followed by sonication for 60 minutes, followed by heating at 80 ℃ and standing for 24 hours after sonication, and the precipitated particles were washed with dimethylformamide and methanol and centrifuged to remove unreacted impurities, and dried overnight under vacuum at 60 ℃ to give a bromine-modified zirconium metal organic framework.

(b) Preparation of polyethylene glycol grafted zirconium Metal organic framework

(b1) Dissolving polyethylene glycol (50g), catalyst silver oxide (6g) and potassium iodide (5g) in dichloromethane (100ml), adding p-toluenesulfonyl chloride (6g), magnetically stirring for 2-3h at room temperature, and filtering to obtain a product A; dissolving the product A (50g) in concentrated ammonia water (25-28%), adding ammonium chloride (100g), magnetically stirring at room temperature for three days, extracting with dichloromethane, and evaporating to remove solvent to obtain polyethylene glycol (HO-PEG-NH2) with hydroxyl at one end and amino at the other end.

(b2) Ultrasonically dispersing a bromine-modified zirconium metal organic framework (10g) in an ethanol solvent, then adding HO-PEG-NH2(60g), uniformly stirring, carrying out grafting reaction for 5h at 30 ℃ in a nitrogen atmosphere, after the reaction is finished, filtering, washing with acetone, and drying to obtain a polyethylene glycol grafted zirconium metal organic framework;

(c) preparation of modified polyimide

(c1) In the nitrogen atmosphere, mixing and stirring 3, 5-diaminobenzoic acid (12g), 4, 4' -diaminodiphenyl ether (60g) and dimethylacetamide uniformly, then adding a dimethylacetamide solution containing pyromellitic dianhydride (100g) into the mixed solution, carrying out synthetic reaction at 20 ℃ for 36h, and obtaining a polyamic acid precursor with carboxyl on the side chain after the reaction is finished;

(c2) dissolving a polyamic acid precursor with a side chain containing carboxyl in dimethylacetamide, diluting into a solution with the mass fraction of 3-8%, carrying out imidization reaction at 120 ℃ for 20h, washing with ethanol after the reaction is finished, and drying to obtain polyimide with a side chain containing carboxyl;

(d) preparation of polyimide Mixed matrix Membrane

(d1) Dissolving polyimide (50g) with carboxyl on a side chain in anhydrous N, N-dimethylformamide (50ml), adding polyethylene glycol grafted zirconium metal organic framework (3g) after uniform ultrasonic dispersion, reacting under the condition of heating and stirring, centrifuging after the reaction is finished, and washing to obtain the zirconium metal organic framework-polyethylene glycol grafted polyimide composite material.

(d2) Dissolving a zirconium metal organic framework-polyethylene glycol grafted polyimide composite material in a dimethylacetamide solvent (25ml), performing ultrasonic treatment for 4 hours, pouring the suspension on a glass mold, evaporating at 60 ℃, performing drying treatment for 24 hours at 120 ℃ for 28 hours to obtain the film applied to CO₂An isolated polyimide mixed matrix membrane.

Example 3

Application to CO₂An isolated polyimide mixed matrix membrane prepared as follows:

(a) preparation of bromine-modified zirconium Metal organic frameworks

Zirconium chloride (1g), 2-bromoterephthalic acid (2g), dimethylformamide (50g) were mixed and sonicated for 40 minutes to ensure complete dissolution of all reactants to give a mixture; terephthalic acid (2g) and dimethylformamide (200g) were poured into the above mixture, followed by sonication for 60 minutes, followed by heating at 80 ℃ and standing for 24 hours after sonication, and the precipitated particles were washed with dimethylformamide and methanol and centrifuged to remove unreacted impurities, and dried overnight under vacuum at 60 ℃ to give a bromine-modified zirconium metal organic framework.

(b) Preparation of polyethylene glycol grafted zirconium Metal organic framework

(b1) Dissolving polyethylene glycol (50g), catalyst silver oxide (8g) and potassium iodide (7.5g) in dichloromethane (100ml), adding p-toluenesulfonyl chloride (7g), magnetically stirring for 2-3h at room temperature, and filtering to obtain a product A; dissolving the product A (50g) in concentrated ammonia water (25-28%), adding ammonium chloride (100g), magnetically stirring at room temperature for three days, extracting with dichloromethane, and evaporating to remove solvent to obtain polyethylene glycol (HO-PEG-NH2) with hydroxyl at one end and amino at the other end.

(b2) Ultrasonically dispersing a bromine-modified zirconium metal organic framework (10g) in an ethanol solvent, then adding HO-PEG-NH2(70g), uniformly stirring, carrying out grafting reaction for 5h at 30 ℃ in a nitrogen atmosphere, after the reaction is finished, filtering, washing with acetone, and drying to obtain a polyethylene glycol grafted zirconium metal organic framework;

(c) preparation of modified polyimide

(c1) In the nitrogen atmosphere, mixing and stirring 3, 5-diaminobenzoic acid (12g), 4, 4' -diaminodiphenyl ether (60g) and dimethylacetamide uniformly, then adding a dimethylacetamide solution containing pyromellitic dianhydride (100g) into the mixed solution, carrying out synthetic reaction at 30 ℃ for 36h, and obtaining a polyamic acid precursor with carboxyl on the side chain after the reaction is finished;

(c2) dissolving a polyamic acid precursor with a side chain containing carboxyl in dimethylacetamide, diluting into a solution with the mass fraction of 3-8%, carrying out imidization reaction at 150 ℃ for 12h, washing with ethanol after the reaction is finished, and drying to obtain polyimide with a side chain containing carboxyl;

(d) preparation of polyimide Mixed matrix Membrane

(d1) Dissolving polyimide (50g) with carboxyl on a side chain in anhydrous N, N-dimethylformamide (50ml), adding polyethylene glycol grafted zirconium metal organic framework (4g) after uniform ultrasonic dispersion, reacting under the condition of heating and stirring, centrifuging after the reaction is finished, and washing to obtain the zirconium metal organic framework-polyethylene glycol grafted polyimide composite material.

(d2) Dissolving a zirconium metal organic framework-polyethylene glycol grafted polyimide composite material in a dimethylacetamide solvent (25ml), performing ultrasonic treatment for 4 hours, pouring the suspension on a glass mold, evaporating at 40 ℃ for 12 hours, and drying the film at 120 ℃ for 28 hours to obtain the composite material applied to CO₂Isolated polyimideAmine mixed matrix membranes.

Example 4

Application to CO₂An isolated polyimide mixed matrix membrane prepared as follows:

(a) preparation of bromine-modified zirconium Metal organic frameworks

Zirconium chloride (1g), 2-bromoterephthalic acid (2g), dimethylformamide (60g) were mixed and sonicated for 120 minutes to ensure complete dissolution of all reactants to give a mixture; terephthalic acid (1g) and dimethylformamide (100g) were poured into the above mixture, followed by sonication for 60 minutes, followed by heating at 70 ℃ and standing for 24 hours after sonication, and the precipitated particles were washed with dimethylformamide and methanol and centrifuged to remove unreacted impurities, and dried overnight under vacuum at 60 ℃ to give a bromine-modified zirconium metal organic framework.

(b) Preparation of polyethylene glycol grafted zirconium Metal organic framework

(b1) Dissolving polyethylene glycol (50g), catalyst silver oxide (8g) and potassium iodide (7.5g) in dichloromethane (100ml), adding p-toluenesulfonyl chloride (7.5g), magnetically stirring at room temperature for 2-3h, and filtering to obtain a product A; dissolving the product A (50g) in concentrated ammonia water (25-28%), adding ammonium chloride (100g), magnetically stirring at room temperature for three days, extracting with dichloromethane, and evaporating to remove solvent to obtain polyethylene glycol (HO-PEG-NH2) with hydroxyl at one end and amino at the other end.

(b2) Ultrasonically dispersing a bromine-modified zirconium metal organic framework (10g) in an ethanol solvent, then adding HO-PEG-NH2(80g), uniformly stirring, carrying out grafting reaction for 2h at 10 ℃ in a nitrogen atmosphere, after the reaction is finished, filtering, washing with acetone, and drying to obtain a polyethylene glycol grafted zirconium metal organic framework;

(c) preparation of modified polyimide

(c1) In the nitrogen atmosphere, mixing and stirring 3, 5-diaminobenzoic acid (12g), 4, 4' -diaminodiphenyl ether (60g) and dimethylacetamide uniformly, then adding a dimethylacetamide solution containing pyromellitic dianhydride (100g) into the mixed solution, carrying out synthetic reaction at 30 ℃ for 36h, and obtaining a polyamic acid precursor with carboxyl on the side chain after the reaction is finished;

(c2) dissolving a polyamic acid precursor with a side chain containing carboxyl in dimethylacetamide, diluting into a solution with the mass fraction of 3-8%, carrying out imidization reaction at 200 ℃ for 36h, washing with ethanol after the reaction is finished, and drying to obtain polyimide with a side chain containing carboxyl;

(d) preparation of polyimide Mixed matrix Membrane

(d1) Dissolving polyimide (50g) with carboxyl on a side chain in anhydrous N, N-dimethylformamide (50ml), adding polyethylene glycol grafted zirconium metal organic framework (5g) after uniform ultrasonic dispersion, reacting under the condition of heating and stirring, centrifuging after the reaction is finished, and washing to obtain the zirconium metal organic framework-polyethylene glycol grafted polyimide composite material.

(d2) Dissolving a zirconium metal organic framework-polyethylene glycol grafted polyimide composite material in a dimethylacetamide solvent (25ml), performing ultrasonic treatment for 4 hours, pouring the suspension on a glass mold, evaporating at 60 ℃, performing drying treatment for 24 hours at 120 ℃ for 28 hours to obtain the film applied to CO₂An isolated polyimide mixed matrix membrane.

Comparative example 1

A polyimide mixed matrix membrane is prepared by the following steps:

(a) preparation of bromine-modified zirconium Metal organic frameworks

Zirconium chloride (1g), 2-bromoterephthalic acid (2g) and dimethylformamide (50g) were mixed and sonicated for 40 minutes to ensure complete dissolution of all reactants to give a mixture; terephthalic acid (1g) and dimethylformamide (100g) were poured into the above mixture, followed by sonication for 60 minutes, followed by heating at 80 ℃ and standing for 24 hours after sonication, and the precipitated particles were washed with dimethylformamide and methanol and centrifuged to remove unreacted impurities, and dried overnight under vacuum at 60 ℃ to give a bromine-modified zirconium metal organic framework.

(b) Preparation of modified polyimide

(b1) In the nitrogen atmosphere, 3, 5-diaminobenzoic acid (8g), 4, 4' -diaminodiphenyl ether (40g) and dimethylacetamide are mixed and stirred uniformly, then dimethylacetamide solution containing pyromellitic dianhydride (100g) is added into the mixed solution, synthetic reaction is carried out for 36h at 20 ℃, and after the reaction is finished, a polyamic acid precursor with carboxyl on the side chain is obtained;

(b2) dissolving a polyamic acid precursor with a side chain containing carboxyl in dimethylacetamide, diluting into a solution with the mass fraction of 3-8%, carrying out imidization reaction at 100 ℃ for 12h, washing with ethanol after the reaction is finished, and drying to obtain polyimide with a side chain containing carboxyl;

(c) preparation of polyimide Mixed matrix Membrane

(c1) Dissolving polyimide (50g) with carboxyl on a side chain in anhydrous N, N-dimethylformamide (50ml), adding a zirconium metal organic framework (2g) after uniform ultrasonic dispersion, reacting under a heating and stirring condition, centrifuging after the reaction is finished, and washing to obtain the zirconium metal organic framework grafted polyimide composite material.

(c2) Dissolving the zirconium metal organic framework grafted polyimide composite material in a dimethylacetamide solvent (25ml), carrying out ultrasonic treatment for 3 hours, pouring the suspension on a glass mold, evaporating at 60 ℃, carrying out drying treatment for 24 hours at 120 ℃ for 28 hours, and obtaining the polyimide mixed matrix membrane.

Comparative example 2

A polyimide mixed matrix membrane is prepared by the following steps:

(a) preparation of modified polyethylene glycol (HO-PEG-NH2)

Dissolving polyethylene glycol (50g), catalyst silver oxide (5g) and potassium iodide (5g) in dichloromethane (100ml), adding p-toluenesulfonyl chloride (6g), magnetically stirring for 2-3h at room temperature, and filtering to obtain a product A; dissolving the product A (50g) in concentrated ammonia water (25-28%), adding ammonium chloride (100g), magnetically stirring at room temperature for three days, extracting with dichloromethane, and evaporating to remove solvent to obtain polyethylene glycol (HO-PEG-NH2) with hydroxyl at one end and amino at the other end.

(b) Preparation of modified polyimide

(b1) In the nitrogen atmosphere, 3, 5-diaminobenzoic acid (8g), 4, 4' -diaminodiphenyl ether (40g) and dimethylacetamide are mixed and stirred uniformly, then dimethylacetamide solution containing pyromellitic dianhydride (100g) is added into the mixed solution, synthetic reaction is carried out for 36h at 20 ℃, and after the reaction is finished, a polyamic acid precursor with carboxyl on the side chain is obtained;

(b2) dissolving a polyamic acid precursor with a side chain containing carboxyl in dimethylacetamide, diluting into a solution with the mass fraction of 3-8%, carrying out imidization reaction at 100 ℃ for 12h, washing with ethanol after the reaction is finished, and drying to obtain polyimide with a side chain containing carboxyl;

(c) preparation of polyimide Mixed matrix Membrane

(c1) Dissolving polyimide (50g) with carboxyl on a side chain in anhydrous N, N-dimethylformamide (50ml), adding polyethylene glycol (2g) after uniform ultrasonic dispersion, reacting under a heating and stirring condition, centrifuging after the reaction is finished, and washing to obtain the polyethylene glycol grafted polyimide composite material.

(c2) Dissolving polyethylene glycol grafted polyimide composite material in dimethylacetamide solvent (25ml), performing ultrasonic treatment for 3 hours, pouring the suspension on a glass mold, evaporating at 60 ℃ for 24 hours, and drying the film at 120 ℃ for 28 hours to obtain the polyethylene glycol grafted polyimide composite material applied to CO₂An isolated polyimide mixed matrix membrane.

Application to CO₂The gas separation characteristic test method of the separated polyimide mixed matrix membrane is a constant volume variable pressure method: the permeability of CH4, N2 and CO2 is respectively tested by using a polyimide film of 6cm2 under the working pressure conditions of 302.15K and 0.2 MPa;

putting the membrane into a membrane separation tester, introducing carbon dioxide/nitrogen (the volume ratio of the carbon dioxide/nitrogen is 50:50) and carbon dioxide/methane (the volume ratio of the carbon dioxide/methane is 50:50), testing the gas flow after the gas flow is stabilized, and calculating the selection coefficient. The test results were as follows:

as can be seen from the above examples 1-4, as the content of polyethylene glycol grafted zirconium metal organic framework increases, the membrane is resistant to CO₂Is greatly increased, relative to N₂And CH₄Has a small influence on the permeability, so that one is applied to CO₂The separated polyimide mixed matrix membrane has better CO capture effect₂The ability of (c); in comparative example 1, the polyethylene glycol was removed as a bridge, and other conditions were identical to those of example 1, and it can be seen that: polyethylene glycol free polyimide mixed matrix membrane to CO₂The capturing ability of (a); in comparative example 2, the zirconium metal organic framework in the film was removed and the other conditions were identical to those of example 1, and it can be seen that: zirconium metal organic framework to CO₂Plays an important role in the capture; with the introduction of the zirconium metal organic framework, the polyimide mixed matrix membrane CO₂The permeability coefficient of (A) is greatly improved. In conclusion, the zirconium metal organic framework and the polyethylene glycol are synergistic and have no defect, so that the polyimide mixed matrix membrane has excellent CO₂Separation capacity.

Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.