A covalent organic framework / polyether sulfone hybrid matrix membrane, and a preparation method and application thereof

Abstract

This invention belongs to the technical field of covalent organic framework membrane materials, and provides a covalent organic framework / polyethersulfone hybrid matrix membrane, its preparation method, and its application. The method includes the following steps: mixing polyethersulfone, a solvent, and trialdehyde-based resorcinol to obtain a trialdehyde-based resorcinol solution; coating the trialdehyde-based resorcinol solution onto a glass fiber filter membrane to obtain a trialdehyde-based resorcinol / polyethersulfone membrane; mixing p-phenylenediamine, a catalyst, and water to obtain a p-phenylenediamine solution; and immersing the trialdehyde-based resorcinol / polyethersulfone membrane in the p-phenylenediamine solution to react, thereby obtaining the covalent organic framework / polyethersulfone hybrid matrix membrane. The preparation method of this invention is mild, and the resulting membrane is uniform and stable, fully combining the high flux of the polymer and the CO2 suppression capabilities of the covalent organic framework. 2 The advantages of strong adsorption separation significantly improve the H2O performance of covalent organic framework / polyethersulfone hybrid matrix membranes. 2 Flux and H 2 / CO 2 Selectivity.

Description

A covalent organic framework / polyethersulfone hybrid matrix membrane, its preparation method and application Technical Field

[0001] This invention relates to the field of covalent organic framework membrane materials technology, and in particular to a covalent organic framework / polyethersulfone hybrid matrix membrane, its preparation method and application. Background Technology

[0002] Hydrogen (H2) is considered one of the carriers of future clean energy. Hydrogen production processes typically contain CO2, and to obtain high-purity hydrogen, it needs to be effectively separated. Membrane separation technology is one method for achieving efficient gas separation. Due to its advantages such as low operating cost, ease of operation, low energy consumption, and environmental friendliness, it is widely used in modern chemical separation processes.

[0003] Hybrid matrix membranes combine the advantages of polymers and fillers, allowing for the independent design of selective, permeable, and support layers to optimize selectivity, permeability, and mechanical properties. Simultaneously, the presence of the support layer facilitates the creation of ultrathin selective layers, thus achieving highly efficient selective separation. Traditional polymer membranes are often affected by the trade-off between permeability and selectivity. Non-solvent-induced phase separation (NIPS) is one of the most commonly used methods for preparing porous polymer membranes. In this process, a non-solvent is introduced into a homogeneous polymer solution, separating the solution into two phases. The polymer-rich phase condenses and becomes the membrane matrix, while the non-polymer phase is removed from the precipitate solution and forms the membrane pores. This traditional NIPS process allows for interconnected structures with adjustable size and porosity to meet the requirements of material transport and separation. After achieving high gas permeability through the introduction of polymers, the next consideration is how to utilize porous materials to achieve high gas selectivity. Therefore, the preparation of novel membrane materials using porous materials has a significant impact on improving membrane performance.

[0004] Covalent organic frameworks (COFs) are periodic crystalline porous materials linked by covalent bonds. The periodic and ordered pores facilitate gas transport, making them a novel material for gas separation membrane construction. To date, COF membranes with gas separation properties have been successfully designed and synthesized, demonstrating their effectiveness in gas separation. However, the synthesis of COF membranes presents several challenges, such as demanding synthesis conditions, poor mechanical properties, and a tendency for intergranular defects to significantly reduce selectivity. Addressing these challenges, and leveraging the fully organic nature and high free volume of COFs to achieve good adhesion and compatibility with polymer matrices, COFs show great potential in the preparation of COF-based hybrid matrix membranes. Summary of the Invention

[0005] The purpose of this invention is to provide a covalent organic framework / polyethersulfone hybrid matrix membrane, its preparation method and application, to solve the problems of poor filler dispersion, easy agglomeration and easy sedimentation of existing hybrid matrix membranes, while improving the brittleness of covalent organic framework membranes and enhancing the application of the membrane in gas separation.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing a covalent organic framework / polyethersulfone hybrid matrix membrane, comprising the following steps:

[0008] (1) Polyethersulfone, solvent and trialdehyde phloroglucinol are mixed to obtain a trialdehyde phloroglucinol solution; the trialdehyde phloroglucinol solution is coated on a glass fiber filter membrane to obtain a trialdehyde phloroglucinol / polyethersulfone membrane;

[0009] (2) Mix p-phenylenediamine, catalyst and water to obtain p-phenylenediamine solution;

[0010] (3) The trialdehyde-based phloroglucinol / polyethersulfone membrane was immersed in a p-phenylenediamine solution to carry out the reaction and obtain the covalent organic framework / polyethersulfone mixed matrix membrane.

[0011] There is no specific order between steps (1) and (2).

[0012] Preferably, the solvent in step (1) is N-methylpyrrolidone;

[0013] The mass ratio of polyethersulfone to solvent is 10–20:80–90; the mass fraction of trialdehyde resorcinol in the trialdehyde resorcinol solution is 1–2%.

[0014] Preferably, the pore size of the glass fiber filter membrane in step (1) is 0.2 to 0.24 μm.

[0015] Preferably, the volume ratio of the trialdehyde phloroglucinol solution in step (1) to the diameter of the glass fiber filter membrane is 1-1.5 mL: 2.3-2.5 cm.

[0016] Preferably, the catalyst in step (2) is p-toluenesulfonic acid monohydrate;

[0017] The mass fraction of p-phenylenediamine in the p-phenylenediamine solution is 0.48–0.5%, and the mass fraction of the catalyst in the p-phenylenediamine solution is 1.68–1.76%.

[0018] Preferably, the temperature of the reaction in step (3) is 20-30°C and the reaction time is 24-72h.

[0019] The present invention also provides a method for preparing the covalent organic framework / polyethersulfone hybrid matrix membrane described above.

[0020] The present invention also provides the application of the aforementioned covalent organic framework / polyethersulfone hybrid matrix membrane in gas separation.

[0021] The beneficial effects of this invention are:

[0022] (1) This invention provides a method for preparing a covalent organic framework / polyethersulfone (POF) hybrid matrix membrane, comprising the following steps: mixing polyethersulfone, a solvent, and trialdehyde resorcinol to obtain a trialdehyde resorcinol solution; coating the trialdehyde resorcinol solution onto a glass fiber filter membrane to obtain a trialdehyde resorcinol / POF membrane; mixing p-phenylenediamine, a catalyst, and water to obtain a p-phenylenediamine solution; and immersing the trialdehyde resorcinol / POF membrane in the p-phenylenediamine solution for reaction to obtain a covalent organic framework / POF hybrid matrix membrane. In the reaction process of this invention, the non-solvent-induced phase separation effect of the polymer polyethersulfone is utilized to generate a solid / liquid interface, allowing the COF layer to undergo in-situ polymerization at the interface, thereby preparing a uniform and stable covalent organic framework / POF hybrid matrix membrane.

[0023] (2) The covalent organic framework / polyethersulfone hybrid matrix membrane provided by the present invention directly uses commercially available ultra-low cost glass fiber filter membrane as macroporous substrate, which greatly reduces the substrate cost. In addition, the glass fiber filter membrane is rich in oxygen-containing groups such as silanol groups, which can form hydrogen bonds and other interactions with the abundant oxygen-containing groups on the surface of polyethersulfone, and form a mutually woven structure with the unique fiber structure of the glass fiber filter membrane, thereby further improving the stability of the covalent organic framework / polyethersulfone hybrid matrix membrane.

[0024] (3) In this invention, the ligand trialdehyde phloroglucinol is directly dissolved in polyethersulfone solution. The non-solvent-induced phase separation of the polymer is used to form a solid / liquid interface, so that the COF layer is polymerized in situ at the interface. This avoids the problem of poor dispersibility of traditional mixed matrix membrane fillers, and solves the problems of brittleness and complicated post-processing in COF membrane preparation by interfacial polymerization, thus simplifying the preparation process.

[0025] (4) The covalent organic framework / polyethersulfone mixed matrix membrane preparation method provided by the present invention has mild conditions, and the resulting membrane is uniform and stable. It fully combines the advantages of high polymer flux and strong CO2 adsorption and separation of covalent organic framework, and greatly improves the H2 flux and H2 / CO2 selectivity of covalent organic framework / polyethersulfone mixed matrix membrane. After being applied to gas separation test, the H2 flux can reach 2671 GPU and the H2 / CO2 separation selectivity is as high as 82. Attached Figure Description

[0026] Figure 1 is a schematic diagram of the structure of COF TpPa-1 in Comparative Example 1;

[0027] Figure 2 shows the X-ray diffraction patterns of different materials (2Theta—2θ, Intensity—intensity);

[0028] Figure 3 shows the microstructure of the covalent organic framework / polyethersulfone hybrid matrix membrane in Example 1; in Figure 3, (a) is the microstructure of the outer surface of the covalent organic framework / polyethersulfone hybrid matrix membrane; (b) is the cross-sectional microstructure of the covalent organic framework / polyethersulfone hybrid matrix membrane.

[0029] Figure 4 is a schematic diagram of the gas separation performance of the covalent organic framework / polyethersulfone hybrid matrix membranes obtained in Examples 1-3 (Permeance—flux, H2 / CO2 selectivity—H2 / CO2 selectivity). Detailed Implementation

[0030] This invention provides a method for preparing a covalent organic framework / polyethersulfone hybrid matrix membrane, comprising the following steps:

[0031] (1) Polyethersulfone, solvent and trialdehyde phloroglucinol are mixed to obtain a trialdehyde phloroglucinol solution; the trialdehyde phloroglucinol solution is coated on a glass fiber filter membrane to obtain a trialdehyde phloroglucinol / polyethersulfone membrane;

[0032] (2) Mix p-phenylenediamine, catalyst and water to obtain p-phenylenediamine solution;

[0033] (3) The trialdehyde-based phloroglucinol / polyethersulfone membrane was immersed in a p-phenylenediamine solution to carry out the reaction and obtain the covalent organic framework / polyethersulfone mixed matrix membrane.

[0034] There is no specific order between steps (1) and (2).

[0035] In this invention, the solvent in step (1) is preferably N-methylpyrrolidone.

[0036] In this invention, the mass ratio of polyethersulfone to solvent is preferably 10-20:80-90, more preferably 12-18:82-88, and even more preferably 15:85; the mass fraction of trialdehyde resorcinol in the trialdehyde resorcinol solution is preferably 1-2%, more preferably 1.2-1.8%, and even more preferably 1.5%.

[0037] In this invention, in step (1), the mixing is preferably as follows: first, polyethersulfone is added to a solvent and stirred until dissolved to obtain a polyethersulfone solution; then, trialdehyde phloroglucinol is added to the polyethersulfone solution and stirred until dissolved to complete the mixing and obtain a trialdehyde phloroglucinol solution.

[0038] In this invention, the pore size of the glass fiber filter membrane in step (1) is preferably 0.2 to 0.24 μm, more preferably 0.21 to 0.23 μm, and even more preferably 0.22 μm.

[0039] In this invention, the volume ratio of the trialdehyde phloroglucinol solution in step (1) to the diameter of the glass fiber filter membrane is preferably 1-1.5 mL: 2.3-2.5 cm, more preferably 1.2-1.4 mL: 2.35-2.45 cm, and even more preferably 1.3 mL: 2.4 cm.

[0040] In this invention, in step (1), the coating method is preferably spin coating, and the glass fiber filter membrane is preferably purchased from Shanghai Xinya Purification Device Factory; the glass fiber filter membrane is placed on a spin coater, and a trialdehyde phloroglucinol solution is slowly spin coated to obtain a trialdehyde phloroglucinol / polyethersulfone membrane; the spin coating speed is preferably 800-1200 r / min, more preferably 900-1100 r / min, and more preferably 1000 r / min; the spin coating time is preferably 50-70 s, more preferably 55-65 s, and more preferably 60 s.

[0041] In this invention, the catalyst in step (2) is preferably p-toluenesulfonic acid monohydrate.

[0042] In this invention, the mass fraction of p-phenylenediamine in the p-phenylenediamine solution is preferably 0.48-0.5%, more preferably 0.485-0.495%, and even more preferably 0.49%; the mass fraction of the catalyst in the p-phenylenediamine solution is preferably 1.68-1.76%, more preferably 1.685-1.756%, and even more preferably 1.75%.

[0043] In this invention, in step (3), there is no specific limitation on the amount relationship between the trialdehyde-based resorcinol / polyethersulfone membrane and the p-phenylenediamine solution, as long as the trialdehyde-based resorcinol / polyethersulfone membrane can be immersed in the p-phenylenediamine solution.

[0044] In this invention, the reaction temperature in step (3) is preferably 20-30°C, more preferably 22-28°C, and even more preferably 25°C; the reaction time is preferably 24-72h, more preferably 36-60h, and even more preferably 48h.

[0045] In this invention, in step (3), after the reaction is completed, the mixture is dried to obtain a covalent organic framework / polyethersulfone mixed matrix membrane; the drying temperature is preferably 20-30°C, more preferably 22-28°C, and even more preferably 25°C; the drying time is preferably 12-36h, more preferably 18-30h, and even more preferably 24h.

[0046] The present invention also provides a method for preparing the covalent organic framework / polyethersulfone hybrid matrix membrane described above.

[0047] The present invention also provides the application of the aforementioned covalent organic framework / polyethersulfone hybrid matrix membrane in gas separation.

[0048] In this invention, a covalent organic framework / polyethersulfone hybrid matrix membrane is applied to gas separation. The covalent organic framework / polyethersulfone hybrid matrix membrane can selectively separate two mixed gases, H2 and CO2, with an H2 flux of up to 2671 GPU and an H2 / CO2 separation selectivity of up to 82.

[0049] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0050] Example 1

[0051] 15g of polyethersulfone (PES) was added to 85g of N-methylpyrrolidone (NMP) solution and stirred to dissolve, obtaining a polyethersulfone solution. Trialdehyde phloroglucinol (Tp) was added to the polyethersulfone solution and stirred until dissolved, obtaining a trialdehyde phloroglucinol solution with a mass fraction of 1.5%. A glass fiber filter membrane with a pore size of 0.22μm and a diameter of 2.5cm was placed on a spin coater, and 1mL of the trialdehyde phloroglucinol solution was slowly spin-coated (the spin-coating speed was set to 1000r / min and the time was 60s) to obtain a trialdehyde phloroglucinol / polyethersulfone membrane, denoted as Tp@PES.

[0052] p-phenylenediamine (Pa-1), p-toluenesulfonic acid monohydrate (PTSA) were mixed with water and stirred until dissolved to obtain a p-phenylenediamine solution. The mass fraction of p-phenylenediamine in the p-phenylenediamine solution was 0.49%, and the mass fraction of the catalyst was 1.75%.

[0053] The Tp@PES membrane was immediately immersed in a p-phenylenediamine solution and reacted at 25°C for 24 hours. After the reaction was completed, it was removed and dried at 25°C for 24 hours to obtain a covalent organic framework / polyethersulfone mixed matrix membrane, denoted as TpPa-1@PES-24.

[0054] Example 2

[0055] Keeping other conditions unchanged in Example 1, the reaction time after immediately immersing the Tp@PES membrane in the p-phenylenediamine solution was changed to 48 hours to obtain a covalent organic framework / polyethersulfone mixed matrix membrane, denoted as TpPa-1@PES-48.

[0056] Example 3

[0057] Keeping other conditions unchanged in Example 1, the reaction time after immediately immersing the Tp@PES membrane in the p-phenylenediamine solution was changed to 72 h to obtain a covalent organic framework / polyethersulfone mixed matrix membrane, denoted as TpPa-1@PES-72.

[0058] Comparative Example 1

[0059] 6.3 mg of trialdehyde phloroglucinol (Tp) was dispersed in 20 mL of dichloromethane to obtain a Tp solution; 97.4 mg of p-phenylenediamine (Pa-1) and 342.3 mg of p-toluenesulfonic acid monohydrate (PTSA) were dissolved in 20 mL of water to obtain a Pa-1 solution.

[0060] The Pa-1 solution was slowly added dropwise to the upper layer of the Tp solution from the top, and allowed to stand at 25°C for 72 h. A COF TpPa-1 layer was formed at the interface between the water and organic phases. The COF TpPa-1 formed at the interface was collected, washed four times with anhydrous acetone, and finally washed four times with anhydrous ethanol to obtain COF TpPa-1 prepared by interfacial polymerization, which was labeled as TpPa-1.

[0061] The structural schematic diagram of COF TpPa-1 in this comparative example is shown in Figure 1.

[0062] X-ray diffraction was used to test the TpPa-1@PES-72 prepared in Example 3, the TpPa-1 prepared in Comparative Example 1, and GF (the glass fiber filter membrane in Example 1). The X-ray diffraction patterns of the different materials are shown in Figure 2. As can be seen from Figure 2, the characteristic peak of COF TpPa-1 was observed at 4.7° for both TpPa-1@PES-72 prepared in Example 3 and TpPa-1 prepared in Comparative Example 1.

[0063] The microstructure of the covalent organic framework / polyethersulfone hybrid matrix membrane prepared in Example 1 was characterized using scanning electron microscopy, resulting in the microstructure characterization images of the covalent organic framework / polyethersulfone hybrid matrix membrane in Example 1, as shown in Figure 3. In Figure 3, (a) is the microstructure characterization image of the outer surface of the covalent organic framework / polyethersulfone hybrid matrix membrane; (b) is the cross-sectional microstructure characterization image of the covalent organic framework / polyethersulfone hybrid matrix membrane. As can be seen from Figure 3, the covalent organic framework / polyethersulfone hybrid matrix membrane covers the surface of the glass fiber microporous filter membrane and penetrates into the interior of the glass fiber filter membrane, forming an interwoven structure with the fiber structure of the glass fiber microporous filter membrane.

[0064] The covalent organic framework / polyethersulfone hybrid matrix membranes prepared in Examples 1-3 were subjected to gas separation performance tests. The specific testing procedure was as follows: the covalent organic framework / polyethersulfone hybrid matrix membrane was installed and fixed in a mold; the membrane sample was sealed with perforated aluminum foil tape; the flow rate of all gas components was controlled using a mass flow meter to ensure a molar ratio of 1:1 between the two gas components and a total flow rate of 100 mL / min. -1 N2 was used as the purge gas at a flow rate of 100 mL / min. -1 Before each measurement, the gas was kept flowing for more than 2 hours to ensure that the gas permeated through the membrane surface at a uniform rate (the permeate flow rate was measured using a soap bubble flow meter). This yielded a schematic diagram of the gas separation performance of the covalent organic framework / polyethersulfone hybrid matrix membranes obtained in Examples 1-3, as shown in Figure 4. Figure 4 shows that the membrane's H2 flux can reach 2671 GPU, and its H2 / CO2 selectivity is as high as 82.

[0065] As can be seen from the above embodiments, the present invention provides a method for preparing a covalent organic framework / polyethersulfone hybrid matrix membrane, comprising the following steps: mixing polyethersulfone, solvent, and trialdehyde resorcinol to obtain a trialdehyde resorcinol solution; coating the trialdehyde resorcinol solution onto a glass fiber filter membrane to obtain a trialdehyde resorcinol / polyethersulfone membrane; mixing p-phenylenediamine, catalyst, and water to obtain a p-phenylenediamine solution; and immersing the trialdehyde resorcinol / polyethersulfone membrane in the p-phenylenediamine solution for reaction to obtain a covalent organic framework / polyethersulfone hybrid matrix membrane. The covalent organic framework / polyethersulfone hybrid matrix membrane preparation method provided by the present invention has mild conditions, and the resulting membrane is uniform and stable, fully combining the advantages of high polymer flux and strong CO2 adsorption and separation of covalent organic frameworks, significantly improving the H2 flux and H2 / CO2 selectivity of the covalent organic framework / polyethersulfone hybrid matrix membrane; after application in gas separation testing, the H2 flux can reach 2671 GPU, and the H2 / CO2 separation selectivity is as high as 82.

[0066] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a covalent organic framework / polyethersulfone hybrid matrix membrane, characterized in that, The process includes the following steps: (1) mixing polyethersulfone, solvent, and trialdehyde resorcinol to obtain a trialdehyde resorcinol solution; coating the trialdehyde resorcinol solution onto a glass fiber filter membrane to obtain a trialdehyde resorcinol / polyethersulfone membrane; (2) mixing p-phenylenediamine, catalyst, and water to obtain a p-phenylenediamine solution; (3) immersing the trialdehyde resorcinol / polyethersulfone membrane in the p-phenylenediamine solution to react and obtain the covalent organic framework / polyethersulfone mixed matrix membrane; there is no order between steps (1) and (2). The order of steps is as follows: In step (1), the mass ratio of polyethersulfone to solvent is 10~20:80~90; the mass fraction of trialdehyde resorcinol in the trialdehyde resorcinol solution is 1~2%; In step (2), the catalyst is p-toluenesulfonic acid monohydrate; the mass fraction of p-phenylenediamine in the p-phenylenediamine solution is 0.48~0.5%, and the mass fraction of the catalyst in the p-phenylenediamine solution is 1.68~1.76%; In step (3), the reaction temperature is 20~30℃, and the reaction time is 24~72h.

2. The method for preparing a covalent organic framework / polyethersulfone hybrid matrix membrane as described in claim 1, characterized in that, The solvent in step (1) is N-methylpyrrolidone.

3. The method for preparing a covalent organic framework / polyethersulfone hybrid matrix membrane as described in claim 1 or 2, characterized in that, The pore size of the glass fiber filter membrane in step (1) is 0.2~0.24μm.

4. The covalent organic framework / polyethersulfone hybrid matrix membrane prepared by the method of any one of claims 1 to 3.

5. The application of the covalent organic framework / polyethersulfone hybrid matrix membrane according to claim 4 in gas separation.

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