Preparation method and application of soft solid porous crystalline framework composite membrane

Abstract

The application discloses a preparation method and application of a soft solid type porous crystalline framework composite membrane. The method comprises the following steps: a discontinuous porous crystalline framework membrane is subjected to interfacial polymerization, ultra-thin polymer is used to block defects and does not cover the surface of the porous crystalline framework material, so that a flexible high-separation-performance membrane with the porous crystalline framework material as a main separation function is obtained. The application has the advantages of simple process, low cost, easy-to-obtain material, easy-to-scale production, and the prepared separation membrane has good separation effect and stability, and has potential application prospect.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation, specifically relating to a soft solid-state porous crystalline framework composite membrane, its preparation and application. Background Technology

[0002] Membrane separation technology is a technique that selectively separates mixtures of molecules with different particle sizes at the molecular level as they pass through a membrane. It offers advantages such as no phase change, low energy consumption, simple operation, good separation effect, and no secondary pollution, and has been widely used in gas separation, seawater desalination, energy-saving technologies, environmental protection, and petrochemicals, generating significant economic benefits. Currently used membrane materials are mainly high-molecular polymers; however, most polymer membranes are constructed from polymeric segments without stacking, lacking molecular-level design and control. Therefore, a "trade-off" effect exists between selectivity and permeate flux during the separation process, making further performance improvements difficult.

[0003] Porous crystalline framework materials, including metal-organic frameworks, covalent-organic frameworks, and molecular sieves, possess advantages such as high porosity, large surface area, uniform pore size, rich variety, and precisely controllable pore structure, making them ideal materials for membrane separation. However, the preparation of porous crystalline framework membranes currently lacks a universally applicable method for easy scale-up, and the irregular stacking of crystallites easily leads to non-selective system defects. Furthermore, the inherent brittleness of porous crystalline framework materials prevents them from being bent after deposition. These problems limit the large-scale industrial application of porous crystalline framework membranes. Mixed matrix membranes can overcome these difficulties in terms of preparation and structure. However, the content of porous crystalline framework materials in the membrane is low (typically below 30 wt%), and the crystallite size is much smaller than the membrane thickness, resulting in separation performance primarily depending on the polymer phase rather than the porous crystalline framework material phase with sieving capabilities. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying a soft solid-state porous crystalline framework composite membrane in which the porous crystalline framework material plays a major separation role and is bendable.

[0005] A method for preparing a soft solid-state porous crystalline framework composite membrane includes the following steps:

[0006] (1) Modify the substrate to provide sufficient nucleation sites for the growth of porous crystalline framework materials;

[0007] (2) A discontinuous porous crystalline framework material film is grown on the substrate obtained in step (1) by in-situ growth, interface synthesis or other methods;

[0008] (3) The discontinuous porous crystalline framework membrane obtained in step (2) is immersed in an aqueous solution containing a polymer monomer A for a certain period of time, so that the polymer monomer fully wets the substrate pores, wherein the concentration of the aqueous solution of polymer monomer A is 0.01wt%-10wt%.

[0009] (4) Take out the discontinuous porous crystalline framework membrane with fully impregnated polymer monomer A obtained in step (3), rinse the membrane surface with an appropriate solvent to remove the monomer A remaining on the membrane surface, and dry it.

[0010] (5) The membrane obtained in step (4) is immersed in the organic solvent of polymer monomer B to carry out interfacial polymerization, ensuring that monomer B undergoes interfacial polymerization on the membrane surface to seal the gaps between the porous crystalline framework particles on the surface; wherein the concentration of the organic solvent of polymer monomer B is 0.01wt%-10wt%.

[0011] (6) After the interfacial polymerization reaction is completed, the membrane is removed and the unreacted monomers are washed away with an appropriate solvent to obtain a soft solid-state porous crystalline framework composite membrane.

[0012] The substrate in step (1) of this invention can be one or more of the commonly used porous organic or inorganic substrates. The substrate is preferably one or more of the following: polysulfone, cellulose acetate, aromatic polyamide, polypiperazine amide, sulfonated polyethersulfone, polyvinylidene fluoride, polyethersulfone, polyvinyl chloride, polyvinyl alcohol, polypropylene, polyethylene, polyimide, polyamide, stainless steel mesh, alumina, etc.

[0013] The porous crystalline framework material selected in step (2) of this invention includes one or a combination of one-dimensional, two-dimensional, and three-dimensional metal-organic frameworks (MOFs), molecular sieves, covalent-organic frameworks (COFs), etc.

[0014] The soaking time in step (3) of the present invention is 1-36000 seconds, the temperature is 0-150℃, the preferred soaking time is 600-1200s, and the preferred temperature is 20-30℃; the polymer monomer A may be one or more of the following: diethylenetriamine, m-phenylenediamine, p-phenylenediamine, hexamethylenediamine, polyethyleneimine, piperazine, tetraethyl orthosilicate, 3-aminopropyltriethoxysiloxane, bovine serum albumin, fibrinogen, 1,6-hexanediol, 1,3-dihydroxyacetone, L-lactic acid, urea, alanine hydrochloride, polyethylene glycol, ethylene glycol, lysine, polyamide, 1,4-butanediol, triethanolamine, melamine, polyethyleneamine, ethylenediamine, etc.

[0015] The appropriate solvent used in step (4) of this invention may be one or more of water, methanol, ethanol, acetone, dichloromethane, n-hexane, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc.

[0016] In step (5) of this invention, the polymer monomer B can be one or more of the following: trimesoyl chloride (TMC), trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, adipyl chloride, cyanoyl chloride, aniline, pyrrole, porphyrin, carbazole, indole, thiophene, etc.; the organic solvent used can be one or more of the following: methanol, ethanol, acetone, dichloromethane, n-hexane, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc.; the interfacial polymerization reaction time is 1-36000 seconds, the reaction temperature is 0-150℃, the preferred reaction time range is 180-600s, and the preferred temperature range is 20-30℃.

[0017] The appropriate solvent used in step (6) of this invention may be one or more of water, methanol, ethanol, acetone, dichloromethane, n-hexane, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc.

[0018] Another aspect of the present invention provides a soft solid-state porous crystalline framework composite membrane prepared by the above method, which is used for separation in the fields of gas separation, pervaporation, reverse osmosis, forward osmosis, nanofiltration, ultrafiltration, and microfiltration.

[0019] This invention uses in-situ or interfacial methods to prepare discontinuous porous crystalline framework material membranes. Through interfacial polymerization, dense ultrathin polymers are used to seal the defects of the porous crystalline framework material without covering its surface, thereby obtaining a flexible membrane with high separation performance where the porous crystalline framework material plays a major separation role.

[0020] The preparation process described in this invention is simple and low-cost, and the materials are readily available and easy to scale up for production. It can effectively solve the problem of difficult film formation of porous crystalline framework materials, and the prepared separation membrane has good separation effect and stability, and has potential application prospects. Attached Figure Description

[0021] This invention appendix Figure 5 The images are respectively

[0022] Figure 1 A schematic diagram of a soft solid-state porous crystalline framework material composite membrane structure;

[0023] Figure 2 Scanning electron microscope (SEM) images of the surface and cross-section of the soft solid-state ZIF-8 composite film;

[0024] Figure 3 This is a schematic diagram of a small-scale pervaporation device used in the experiment;

[0025] Figure 4 A schematic diagram of the pervaporation process of a soft solid porous crystalline framework composite membrane;

[0026] Figure 5 This is a schematic diagram of a small nanofiltration device used in the experiment. Detailed Implementation

[0027] The soft solid-state porous crystalline framework material composite membrane and its separation performance of the present invention will be further described in detail below with reference to embodiments. However, the present invention is not limited to the following embodiments.

[0028] Example 1

[0029] The structure of a soft solid-state porous crystalline framework material composite membrane is as follows: Figure 1 As shown, a dense and continuous polymer phase is used to connect discontinuous porous crystalline framework materials without covering the upper and lower surfaces of the crystalline materials, thereby obtaining a composite membrane with the porous crystalline framework material as the main mass transfer channel. The separation membrane preparation method is as follows:

[0030] (1) A commercial polyvinylidene fluoride (PVDF) microfiltration membrane (0.22 μm) disc with a diameter of 4 cm was immersed in a 2 mol / L NaOH aqueous solution for 12 h, then removed and treated with a large amount of water; then the treated PVDF membrane was placed in a solution containing 5 mL acrylic monomer, 1 g NaHSO3 and 1 g (NH4)S2O8, reacted at 60 °C for 6 h, removed and rinsed with a large amount of water to obtain a polypropylene modified PVDF (PAA-g-PVDF) membrane;

[0031] (2) Weigh 0.215g ZnCl2, 0.259g 2-methylimidazole and 0.107g sodium acetate and dissolve them in 20mL methanol. Then, vertically place the PAA-g-PVDF membrane obtained in step (1) into the reaction vessel, add the above solution, and react at 85℃ for 16 hours to obtain the discontinuous ZIF-8 membrane.

[0032] (3) The discontinuous ZIF-8 membrane obtained in step (2) is first soaked in ethanol for 5 minutes and then transferred to deionized water to fully exchange the ethanol in the membrane. Then, the membrane is soaked in an aqueous solution containing 1 wt% diethylenetriamine (DETA) for 20 minutes at a soaking temperature of 25°C. After soaking, the membrane surface is quickly rinsed with deionized water and ethanol and dried. Then, it is placed in a toluene solution containing 1 wt% trimesoyl chloride (TMC) at room temperature for interfacial polymerization for 5 minutes. Finally, the resulting composite membrane is taken out and rinsed with deionized water, toluene, and ethanol in sequence to remove unreacted monomers. It is then air-dried at room temperature to obtain a soft solid-state ZIF-8 separation membrane for gas separation. From the electron microscope image of the membrane ( Figure 2As can be seen from the data, the continuous phase polyamide film can fill the gaps between ZIF-8 particles without covering the surface of ZIF-8, indicating that a bicontinuous ZIF-8 composite film was successfully prepared.

[0033] The obtained separation membrane was tested for gas separation performance in a Wicke-Kallenbach membrane module. The test gas was a 1:1 H2 / CO2 mixture, the temperature was 25 degrees Celsius, the transmembrane pressure difference was 0 MPa, and argon was used as the purge gas.

[0034] The measured membrane separation performance for H2 / CO2 is as follows: H2 permeability is 1796 GPU, and H2 / CO2 separation ratio is 102.

[0035] Example 2

[0036] Separation membrane preparation method:

[0037] (1) A 4 cm diameter commercial polyvinylidene fluoride (PVDF) microfiltration membrane (0.22 μm) disc was immersed in a 2 mol / L NaOH aqueous solution for 12 h, then removed and treated with a large amount of water; then the treated PVDF membrane was placed in a solution containing 5 mL acrylic monomer, 1 g NaHSO3 and 1 g (NH4)S2O8, reacted at 60 °C for 6 h, removed and rinsed with a large amount of water to obtain a polypropylene modified PVDF (PAA-g-PVDF) membrane.

[0038] (2) Weigh 0.215g ZnCl2, 0.259g 2-methylimidazole and 0.107g sodium acetate and dissolve them in 20mL methanol. Then, vertically place the PAA-g-PVDF membrane obtained in step (1) into the reaction vessel, add the above solution, and react at 85℃ for 16 hours to obtain the discontinuous ZIF-8 membrane.

[0039] (3) The discontinuous ZIF-8 membrane obtained in step (2) is first soaked in ethanol for 5 minutes and then transferred to deionized water to fully exchange the ethanol in the membrane. Then the membrane is soaked in an aqueous solution containing 1 wt% diethylenetriamine (DETA) for 20 minutes at a soaking temperature of 25°C. After soaking, the membrane surface is quickly rinsed with deionized water and ethanol and dried. Then it is placed in a toluene solution containing 1 wt% trimesoyl chloride (TMC) at room temperature for interfacial polymerization reaction for 5 minutes. Finally, the obtained composite membrane is taken out and rinsed with deionized water, toluene and ethanol in sequence to remove unreacted monomers. It is then dried at room temperature to obtain a soft solid ZIF-8 separation membrane for gas separation.

[0040] The obtained separation membrane was tested for gas separation performance in a Wicke-Kallenbach membrane module. The test gas was a 1:1 H2 / CH4 mixture, the temperature was 25 degrees Celsius, the transmembrane pressure difference was 0 MPa, and argon was used as the purge gas.

[0041] The measured membrane separation performance for H2 / CH4 is as follows: H2 permeability is 1515 GPU, and H2 / CH4 separation ratio is 30.

[0042] Example 3

[0043] Separation membrane preparation method:

[0044] (1) A commercial polyvinylidene fluoride (PVDF) microfiltration membrane (0.22 μm) disc with a diameter of 10 cm was immersed in a 2 mol / L NaOH aqueous solution for 12 h, then removed and treated with a large amount of water; then the treated PVDF membrane was placed in a solution containing 5 mL acrylic monomer, 1 g NaHSO3 and 1 g (NH4)S2O8, reacted at 60 °C for 6 h, removed and rinsed with a large amount of water to obtain a polypropylene modified PVDF (PAA-g-PVDF) membrane;

[0045] (2) The PAA-g-PVDF membrane obtained in step (1) was immersed in an ethanol solution containing 0.5 mol / L Zn(NO3)2·6H2O for 12 hours, then removed and vacuum dried at 50 degrees Celsius for 12 hours to obtain Zn 2+ @PVDF membrane;

[0046] (3) Weigh 0.57g Zn(NO3)2·6H2O and 0.31g benzimidazole and dissolve them in 30mL of a mixed solvent of DMF and H2O (volume ratio 1:1). Then, dissolve the Zn obtained in step (2) in the solution. 2+ @Place the PVDF membrane vertically into the reactor, add the above solution, and react at 100℃ for 3 days to obtain the discontinuous Zn2(Bim)4 membrane;

[0047] (4) The discontinuous Zn2(Bim)4 membrane obtained in (3) is first soaked in ethanol for 5 minutes and then transferred to deionized water to fully exchange the ethanol in the membrane. Then the membrane is soaked in an aqueous solution containing 1 wt% diethylenetriamine (DETA) for 20 minutes at a soaking temperature of 25°C. After soaking, the membrane surface is quickly rinsed with deionized water and ethanol and dried. Then it is placed in a toluene solution containing 1 wt% trimesoyl chloride (TMC) at room temperature for interfacial polymerization reaction for 5 minutes. Finally, the composite membrane is taken out and rinsed with deionized water, toluene and ethanol in sequence to remove unreacted monomers. It is then dried at room temperature to obtain a soft solid Zn2(Bim)4 separation membrane for gas separation.

[0048] The obtained separation membrane was tested for gas separation performance in a Wicke-Kallenbach membrane module. The test gas was a 1:1 H2 / CO2 mixture, the temperature was 25 degrees Celsius, the transmembrane pressure difference was 0 MPa, and argon was used as the purge gas.

[0049] The measured separation performance of the membrane for H2 / CO2 is as follows: H2 permeability is 1017 GPU, and H2 / CO2 separation ratio is 311.

[0050] Example 4

[0051] Separation membrane preparation method:

[0052] (1) A 4 cm diameter commercial polyvinylidene fluoride (PVDF) microfiltration membrane (0.22 μm) disc was immersed in a 2 mol / L NaOH aqueous solution for 12 h, then removed and treated with a large amount of water; then the treated PVDF membrane was placed in a solution containing 5 mL acrylic monomer, 1 g NaHSO3 and 1 g (NH4)S2O8, reacted at 60 °C for 6 h, removed and rinsed with a large amount of water to obtain a polypropylene modified PVDF (PAA-g-PVDF) membrane.

[0053] (2) The PAA-g-PVDF membrane obtained in step (1) was immersed in an ethanol solution containing 0.5 mol / L Co(NO3)2·6H2O for 12 hours, then removed and vacuum dried at 50 degrees Celsius for 12 hours to obtain Co. 2+ @PVDF membrane;

[0054] (3) Weigh 1.02g of 2-methylimidazole, 0.25g of sodium formate, and 0.74g of CoCl2·6H2O and dissolve them in 50mL of methanol. Then, dissolve the Co obtained in step (2) in the methanol solution. 2+ @Place the PVDF membrane vertically into the reactor, add the above solution, and react at 100℃ for 3 days to obtain the discontinuous ZIF-67 membrane;

[0055] (4) The discontinuous ZIF-67 membrane obtained in step (3) is first soaked in ethanol for 5 minutes and then transferred to deionized water to fully exchange the ethanol in the membrane. Then the membrane is soaked in an aqueous solution containing 1 wt% diethylenetriamine (DETA) for 20 minutes at a soaking temperature of 25°C. After soaking, the membrane surface is quickly rinsed with deionized water and ethanol and dried. Then it is placed in a toluene solution containing 1 wt% trimesoyl chloride (TMC) for interfacial polymerization at room temperature for 5 minutes. Finally, the composite membrane is taken out and rinsed with deionized water, toluene and ethanol in sequence to remove unreacted monomers. It is then dried at room temperature to obtain a soft solid ZIF-67 separation membrane for gas separation.

[0056] The obtained separation membrane was tested for gas separation performance in a Wicke-Kallenbach membrane module. The test gas was a 1:1 H2 / CH4 mixture, the temperature was 25 degrees Celsius, the transmembrane pressure difference was 0 MPa, and argon was used as the purge gas.

[0057] The measured membrane separation performance for H2 / CH4 is as follows: H2 permeability is 1473 GPU, and H2 / CO2 separation ratio is 112.

[0058] Example 5

[0059] Separation membrane preparation method:

[0060] (1) A 4 cm diameter commercial polyvinylidene fluoride (PVDF) microfiltration membrane (0.22 μm) disc was immersed in a 2 mol / L NaOH aqueous solution for 12 h, then removed and treated with a large amount of water; then the treated PVDF membrane was placed in a solution containing 5 mL acrylic monomer, 1 g NaHSO3 and 1 g (NH4)S2O8, reacted at 60 °C for 6 h, removed and rinsed with a large amount of water to obtain a polypropylene modified PVDF (PAA-g-PVDF) membrane.

[0061] (2) The PAA-g-PVDF membrane obtained in step (1) was immersed in an ethanol solution containing 0.5 mol / L Co(NO3)2·6H2O for 12 hours, then removed and vacuum dried at 50 degrees Celsius for 12 hours to obtain Co. 2+ @PVDF membrane;

[0062] (3) Weigh 1.02g of 2-methylimidazole, 0.25g of sodium formate, and 0.74g of CoCl2·6H2O and dissolve them in 50mL of methanol. Then, dissolve the Co obtained in step (2) in the methanol solution. 2+ @Place the PVDF membrane vertically into the reactor, add the above solution, and react at 100℃ for 3 days to obtain the discontinuous ZIF-67 membrane;

[0063] (4) The discontinuous ZIF-67 membrane obtained in step (3) is first soaked in ethanol for 5 minutes and then transferred to deionized water to fully exchange the ethanol in the membrane. Then the membrane is soaked in an aqueous solution containing 1 wt% diethylenetriamine (DETA) for 20 minutes at a soaking temperature of 25°C. After soaking, the membrane surface is quickly rinsed with deionized water and ethanol and dried. Then it is placed in a toluene solution containing 1 wt% trimesoyl chloride (TMC) for interfacial polymerization at room temperature for 5 minutes. Finally, the composite membrane is taken out and rinsed with deionized water, toluene and ethanol in sequence to remove unreacted monomers. It is then dried at room temperature to obtain a soft solid ZIF-67 separation membrane for gas separation.

[0064] The obtained separation membrane was tested for gas separation performance in a Wicke-Kallenbach membrane module. The test gas was a 1:1 H2 / CO2 mixture, the temperature was 25 degrees Celsius, the transmembrane pressure difference was 0 MPa, and argon was used as the purge gas.

[0065] The measured separation performance of the membrane for H2 / CO2 is as follows: H2 permeability is 1496 GPU, and H2 / CO2 separation ratio is 328.

[0066] Example 6

[0067] Separation membrane preparation method:

[0068] (1) A 4 cm diameter commercial polyvinylidene fluoride (PVDF) microfiltration membrane (0.22 μm) disc was immersed in a 2 mol / L NaOH aqueous solution for 12 h, then removed and treated with a large amount of water; then the treated PVDF membrane was placed in a solution containing 5 mL acrylic monomer, 1 g NaHSO3 and 1 g (NH4)S2O8, reacted at 60 °C for 6 h, removed and rinsed with a large amount of water to obtain a polypropylene modified PVDF (PAA-g-PVDF) membrane.

[0069] (2) Weigh 0.215g ZnCl2, 0.259g 2-methylimidazole and 0.107g sodium acetate and dissolve them in 20mL methanol. Then, vertically place the PAA-g-PVDF membrane obtained in step (1) into the reaction vessel, add the above solution, and react at 85℃ for 16 hours to obtain the discontinuous ZIF-8 membrane.

[0070] (3) The discontinuous ZIF-8 membrane obtained in step (2) is first soaked in ethanol for 5 minutes and then transferred to deionized water to fully exchange the ethanol in the membrane. Then the membrane is soaked in an aqueous solution containing 1 wt% diethylenetriamine (DETA) for 20 minutes at a soaking temperature of 25°C. After soaking, the membrane surface is quickly rinsed with deionized water and ethanol and dried. Then it is placed in a toluene solution containing 1 wt% trimesoyl chloride (TMC) at room temperature for interfacial polymerization reaction for 5 minutes. Finally, the obtained composite membrane is taken out and rinsed with deionized water, toluene and ethanol in sequence to remove unreacted monomers. It is then dried at room temperature to obtain a soft solid ZIF-8 separation membrane for pervaporation separation.

[0071] Pervaporation test:

[0072] Figure 3 This is a schematic diagram of a pervaporation device that was independently built in the laboratory (wherein, Figure 3 a represents the pervaporation testing device. Figure 3 b is the membrane module used in the test). This process, driven by pressure, fully utilizes the differences in dissolution and diffusion rates of components in the mixture through the membrane to achieve separation. Atmospheric pressure is maintained on the feed side, and the components undergo adsorption and sieving (e.g., Figure 4 As shown, vaporization occurs after passing through the membrane, and the latent heat required for the phase change comes from the sensible heat of the feedstock. The permeate side is maintained at low pressure by vacuuming, and the permeated component vapor is condensed and collected by liquid nitrogen. However, when the mixture is fed in the form of vapor, no phase change occurs as the component passes through the membrane; this process is called vapor permeation. From equations 1-1 and 1-2, the permeability P of component A through the membrane can be obtained. A From the adsorption coefficient S of the membrane A and diffusion coefficient D A Together, they determine the membrane's selectivity α for separating components A and B. A / B This is its adsorption selectivity S A / S B and D A / D B The product of.

[0073] P A =S A *S B (1-1)

[0074] α A / B =(S A / S B )*(D A / D B (1-2)

[0075] The total permeability P of the membrane and the selectivity of component A to component B, αA / B, are two important parameters for evaluating membrane separation performance. In experiments, the total permeability P per unit time and unit area of ​​the membrane can be calculated using the mass W of the permeate collected on the permeate side, the membrane area A, and the pervaporation time t, as shown in Equation 1-3. Gas chromatography can analyze and provide the component contents (xA,F,xB,F,yA,P,yB,P) of the feed solution and permeate, and αA / B can be obtained using Equation 1-4.

[0076] P = W / (A*t) (1-3)

[0077] α A / B =(x B,F / x A,F )(y A,P / y B,P (1-4)

[0078] The measured membrane separation performance for water / ethanol is as follows: water permeability is 6846 g m³. -2 h -1 The water / ethanol separation ratio is 1121.

[0079] Example 7

[0080] Separation membrane preparation method:

[0081] (1) A commercial polyvinylidene fluoride (PVDF) microfiltration membrane (0.22 μm) was soaked in a 2 mol / L NaOH aqueous solution for 12 h, then removed and treated with a large amount of water; then the treated PVDF membrane was placed in a solution containing 5 mL acrylic monomer, 1 g NaHSO3 and 1 g (NH4)S2O8, reacted at 60 °C for 6 h, removed and rinsed with a large amount of water to obtain a polypropylene modified PVDF (PAA-g-PVDF) membrane;

[0082] (2) Weigh 0.215g ZnCl2, 0.259g 2-methylimidazole and 0.107g sodium acetate and dissolve them in 20mL methanol. Then, vertically place the PAA-g-PVDF membrane obtained in step (1) into the reaction vessel, add the above solution, and react at 85℃ for 16 hours to obtain the discontinuous ZIF-8 membrane.

[0083] (3) The discontinuous ZIF-8 membrane obtained in step (2) is first soaked in ethanol for 5 minutes and then transferred to deionized water to fully exchange the ethanol in the membrane. Then the membrane is soaked in an aqueous solution containing 1 wt% diethylenetriamine (DETA) for 20 minutes. After soaking, the membrane surface is quickly rinsed with deionized water and ethanol and dried. Then it is placed in a toluene solution containing 1 wt% trimesoyl chloride (TMC) for interfacial polymerization at room temperature for 5 minutes. Finally, the obtained composite membrane is taken out and rinsed with deionized water, toluene and ethanol in sequence to remove unreacted monomers. It is then dried at room temperature to obtain a soft solid ZIF-8 separation membrane for nanofiltration separation.

[0084] The resulting separation membrane was tested for dye removal performance in a nanofiltration unit (e.g., Figure 5 The test system was an aqueous solution of 0.1 g / L methylene blue (MW = 799.8), the test pressure was 0.5 MPa, and the test temperature was room temperature.

[0085] The measured removal performance of the separation membrane for methylene blue is as follows: flux is 693 L·m -2 ·h -1 ·MPa -1 The rejection rate for methylene blue was 99.99%.

[0086] Example 8

[0087] Scale-up preparation method of separation membrane:

[0088] (1) A commercial polyvinylidene fluoride (PVDF) microfiltration membrane (0.22 μm) was cut into 80×80 cm membranes and soaked in 2 mol / L NaOH aqueous solution for 12 h. Then it was taken out and treated with a large amount of water. Then the treated PVDF membrane was placed in a solution containing 50 mL acrylic monomer, 10 g NaHSO3 and 10 g (NH4)S2O8 and reacted at 60 °C for 6 h. After taking it out, it was rinsed with a large amount of water to obtain polypropylene modified PVDF (PAA-g-PVDF) membrane.

[0089] (2) Weigh 8.6g ZnCl2, 10.36g 2-methylimidazole and 4.28g sodium acetate and dissolve them in 800mL methanol. Then, vertically place the PAA-g-PVDF membrane obtained in step (1) into the reaction vessel, add the above solution, and react at 85℃ for 16 hours to obtain the discontinuous ZIF-8 membrane.

[0090] (3) The discontinuous ZIF-8 membrane obtained in step (2) is first soaked in ethanol for 5 minutes and then transferred to deionized water to fully exchange the ethanol in the membrane. Then the membrane is soaked in an aqueous solution containing 1 wt% diethylenetriamine (DETA) for 20 minutes at a soaking temperature of 25°C. After soaking, the membrane surface is quickly rinsed with deionized water and ethanol and dried. Then it is placed in a toluene solution containing 1 wt% trimesoyl chloride (TMC) at room temperature for interfacial polymerization reaction for 5 minutes. Finally, the obtained composite membrane is taken out and rinsed with deionized water, toluene and ethanol in sequence to remove unreacted monomers. It is then dried at room temperature to obtain a soft solid ZIF-8 separation membrane for gas separation.

[0091] The obtained separation membrane was tested for gas separation performance in a Wicke-Kallenbach membrane module. The test gas was a 1:1 H2 / CO2 mixture, the temperature was 25 degrees Celsius, the transmembrane pressure difference was 0 MPa, and argon was used as the purge gas.

[0092] The measured membrane separation performance for H2 / CO2 is as follows: H2 permeability is 1752 GPU, and H2 / CO2 separation ratio is 97.

[0093] Example 9

[0094] Hollow fiber separation membrane preparation method:

[0095] (1) A PVDF hollow fiber membrane (50 cm long, 1.1 mm outer diameter, 0.5 mm inner diameter, and 50 nm average pore size) was soaked in a 2 mol / L NaOH aqueous solution for 12 h, then removed and treated with a large amount of water; then the treated PVDF hollow fiber was placed in a solution containing 50 mL acrylic monomer, 10 g NaHSO3 and 10 g (NH4)S2O8, reacted at 60 °C for 6 h, removed and rinsed with a large amount of water to obtain polypropylene modified PVDF (PAA-g-PVDF) hollow fiber tube;

[0096] (2) Weigh 8.6g ZnCl2, 10.36g 2-methylimidazole and 4.28g sodium acetate and dissolve them in 800mL methanol. Then fix the PAA-g-PVDF hollow fiber membrane obtained in step (1) on the support (6 pieces / group) and place it vertically into the reaction vessel. Add the above solution and react at 85℃ for 16 hours to obtain the discontinuous ZIF-8 membrane.

[0097] (3) The discontinuous ZIF-8 membrane obtained in step (2) is first soaked in ethanol for 5 minutes and then transferred to deionized water to fully exchange the ethanol in the membrane. Then the membrane is soaked in an aqueous solution containing 1 wt% diethylenetriamine (DETA) for 20 minutes at a soaking temperature of 25°C. After soaking, the membrane surface is quickly rinsed with deionized water and ethanol and dried. Then it is placed in a toluene solution containing 1 wt% trimesoyl chloride (TMC) at room temperature for interfacial polymerization reaction for 5 minutes. Finally, the obtained composite membrane is taken out and rinsed with deionized water, toluene and ethanol in sequence to remove unreacted monomers. It is then dried at room temperature to obtain a soft solid ZIF-8 separation membrane for gas separation.

[0098] The obtained separation membrane was tested for gas separation performance in a Wicke-Kallenbach membrane module. The test gas was a 1:1 H2 / CO2 mixture, the temperature was 25 degrees Celsius, the transmembrane pressure difference was 0 MPa, and argon was used as the purge gas.

[0099] The measured separation performance of the membrane for H2 / CO2 is as follows: H2 permeability is 1924 GPU, and H2 / CO2 separation ratio is 105.

[0100] Example 10

[0101] Separation membrane preparation method:

[0102] (1) A 4 cm diameter commercial polyvinylidene fluoride (PVDF) microfiltration membrane (0.22 μm) disc was immersed in a 2 mol / L NaOH aqueous solution for 12 h, then removed and treated with a large amount of water; then the treated PVDF membrane was placed in a solution containing 5 mL acrylic monomer, 1 g NaHSO3 and 1 g (NH4)S2O8, reacted at 60 °C for 6 h, removed and rinsed with a large amount of water to obtain a polypropylene modified PVDF (PAA-g-PVDF) membrane.

[0103] (2) Weigh 0.315g of trialdehyde phloroglucinol and 0.07383g of hydrazine and pour them into a Schlank tube containing a PAA-g-PVDF membrane. Then add 1.5mL of mesitylene, 1.5mL of 1,4-dioxane and 0.5mL of acetic acid aqueous solution (3M). Sonicate for 5 minutes and remove the air by vacuuming. Then place the reaction in an oil bath at 110℃ for 3 days to obtain a discontinuous TpHz-COF membrane.

[0104] (3) The discontinuous TpHz-COF membrane obtained in step (2) is first soaked in ethanol for 5 minutes and then transferred to deionized water to fully exchange the ethanol in the membrane. Then the membrane is soaked in an aqueous solution containing 1 wt% diethylenetriamine (DETA) for 20 minutes at a soaking temperature of 25°C. After soaking, the membrane surface is quickly rinsed with deionized water and ethanol and dried. Then it is placed in a toluene solution containing 1 wt% trimesoyl chloride (TMC) at room temperature for interfacial polymerization reaction for 5 minutes. Finally, the obtained composite membrane is taken out and rinsed with deionized water, toluene and ethanol in sequence to remove unreacted monomers. It is then dried at room temperature to obtain a soft solid TpHz-COF separation membrane for gas separation.

[0105] The obtained separation membrane was tested for gas separation performance in a Wicke-Kallenbach membrane module. The test gas was a 1:1 H2 / CO2 mixture, the temperature was 25 degrees Celsius, the transmembrane pressure difference was 0 MPa, and argon was used as the purge gas.

[0106] The measured separation performance of the membrane for H2 / CO2 is as follows: CO2 permeation is 150 GPU, and CO2 / H2 separation ratio is 10.

[0107] Example 11

[0108] Separation membrane preparation method:

[0109] (1) A 4 cm diameter commercial polyvinylidene fluoride (PVDF) microfiltration membrane (0.22 μm) disc was immersed in a 2 mol / L NaOH aqueous solution for 12 h, then removed and treated with a large amount of water; then the treated PVDF membrane was placed in a solution containing 5 mL acrylic monomer, 1 g NaHSO3 and 1 g (NH4)S2O8, reacted at 60 °C for 6 h, removed and rinsed with a large amount of water to obtain a polypropylene modified PVDF (PAA-g-PVDF) membrane.

[0110] (2) Weigh 7.6g of tetrapropylammonium hydroxide (20wt% aqueous solution) and 7.5g of tetraethyl orthosilicate and dissolve them in 60g of deionized water. Then, vertically place the PAA-g-PVDF membrane obtained in step (1) into the reaction vessel, add the above solution, and react at 110℃ for 24 hours to obtain the discontinuous MFI molecular sieve membrane.

[0111] (3) The discontinuous MFI membrane obtained in step (2) is first soaked in ethanol for 5 minutes and then transferred to deionized water to fully exchange the ethanol in the membrane. Then the membrane is soaked in an aqueous solution containing 1 wt% diethylenetriamine (DETA) for 20 minutes at a soaking temperature of 25°C. After soaking, the membrane surface is quickly rinsed with deionized water and ethanol and dried. Then it is placed in a toluene solution containing 1 wt% trimesoyl chloride (TMC) at room temperature for interfacial polymerization reaction for 5 minutes. Finally, the obtained composite membrane is taken out and rinsed with deionized water, toluene and ethanol in sequence to remove unreacted monomers. It is then dried at room temperature to obtain a soft solid MFI separation membrane for gas separation.

[0112] The obtained separation membrane was tested for gas separation performance in a Wicke-Kallenbach membrane module. The test gas was a 1:1 mixture of n-butane and isobutane, the temperature was 25 degrees Celsius, the transmembrane pressure difference was 0 MPa, and argon was used as the purge gas.

[0113] The measured membrane separation performance for H2 / CO2 is as follows: n-butane permeate is 854 GPU, and n-butane / isobutane separation ratio is 47.

Claims

1. A method for preparing a soft solid-state porous crystalline framework composite membrane, characterized in that, Includes the following steps: (1) Modify the substrate to provide sufficient nucleation sites for the growth of porous crystalline framework materials; (2) A discontinuous porous crystalline framework material film is grown on the substrate obtained in step (1) by in-situ growth; (3) Immerse the discontinuous porous crystalline framework material membrane obtained in step (2) in an aqueous solution containing polymer monomer A for 20-100 minutes at a temperature of 0-150°C to ensure that the polymer monomer fully wets the substrate pores; wherein the concentration of the aqueous solution of polymer monomer A is 0.01 wt% - 10 wt% (4) Take out the discontinuous porous crystalline framework material film that is fully wetted with polymer monomer A obtained in step (3), rinse the film surface with solvent to remove the residual monomer A on the film surface, and dry it; (5) Introduce the membrane obtained in step (4) into a solution containing polymer monomer B in an organic solvent for interfacial polymerization to ensure that monomer B undergoes interfacial polymerization on the membrane surface, sealing the gaps between the porous crystalline framework particles on the surface; wherein the concentration of the solution containing polymer monomer B in the organic solvent is 0.01 wt% - 10 wt%; (6) After the interfacial polymerization reaction is completed, the membrane is removed and the unreacted monomers are washed away with solvent to obtain a soft solid porous crystalline framework composite membrane. The solvents used in steps (4) and (6) are one or more of the following: water, methanol, ethanol, acetone, dichloromethane, chloroform, n-hexane, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. The substrate is polyvinylidene fluoride. In step (1), the substrate is modified to obtain polypropylene-modified polyvinylidene fluoride. The porous crystalline framework material in step (2) is selected from one or a combination of several of molecular sieves, covalent-organic framework materials, or one-dimensional, two-dimensional, and three-dimensional metal-organic framework materials; In step (3), polymer monomer A is diethylenetriamine; In step (5), the polymer monomer B is trimesoyl chloride; the organic solvent used is one or more of methanol, ethanol, acetone, dichloromethane, n-hexane, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide; the interfacial polymerization time is 180-36000 seconds, and the reaction temperature is 0-150 degrees Celsius.

2. The method for preparing a soft solid-state porous crystalline framework composite membrane according to claim 1, characterized in that, The structure of the substrate is one or more of the following: flat plate, sheet, tubular, and hollow fiber.

3. The soft solid-state porous crystalline framework composite membrane prepared by the method according to any one of claims 1-2.

4. The soft solid-state porous crystalline framework composite membrane of claim 3 is used for separation in the fields of gas separation, pervaporation, and nanofiltration, characterized in that, Gas separation includes the separation of H2 and CO2, H2 and CH4, and n-butane and isobutane; pervaporation is used to separate water and ethanol; and nanofiltration is used to remove methylene blue from an aqueous solution of methylene blue.

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