Hollow fiber composite matrix membrane

Abstract

The invention provides a hollow fiber composite matrix membrane, and belongs to the technical field of hollow fiber membranes. According to the invention, MOFs is used as a crystalline porous material and is used as a metal framework, and an inorganic metal center and a bridged organic ligand are self-assembled to form a periodic network structure; on the basis, carrying out a polymerization reaction with bis (4-aminophenyl) ether and hexafluorodianhydride, and then carrying out an imine condensation reaction with acetic anhydride under the catalysis of triethylamine to obtain a composite matrix membrane casting solution; the composite matrix membrane prepared from the membrane casting solution has a surface macroporous structure and an internal support structure, and can significantly improve the nitrogen-oxygen separation efficiency. According to the invention, N-methyl-2-pyrrolidone, ethanol and polyethylene glycol are adopted to construct a core liquid; and solidifying the extruded fiber membrane filaments in a water bath, modifying the fiber membrane filaments by using an organic solvent, and finally rinsing to obtain a finished product. The hollow fiber composite matrix membrane has good selectivity on nitrogen and oxygen molecules, is high in separation speed, can greatly improve the separation efficiency of nitrogen and oxygen in air, and is suitable for large-scale application.

Description

Technical Field

[0001] The invention relates to the technical field of hollow fiber membranes, in particular to a hollow fiber composite matrix membrane. Background Art

[0002] Hollow fiber membrane is a polymer material film with selective separation function. Its structural feature is that it is hollow fiber inside, hence the name. It is mainly made of raw materials such as polysulfone and dimethylacetamide, and has self-supporting function and selective permeability characteristics. The outer diameter of the hollow fiber membrane is usually 500~600 microns, the inner diameter is 200~300 microns, and the fiber bundle length can reach 3~6 meters. One end of the fiber bundle is sealed, and the other end is bonded together with a specially formulated epoxy resin and loaded into a high-pressure resistant metal shell. Due to the different permeation rates of different gases or liquids, hollow fiber membranes can achieve selective separation.

[0003] Nitrogen-oxygen separation is the process of separating nitrogen and oxygen in the air. Hollow fiber membrane is a polymer membrane material with a specific structure. Different gas molecules have different adsorption and solubility on the membrane surface. For example, oxygen molecules have a higher solubility coefficient in some membrane materials than nitrogen molecules, which makes oxygen more easily soluble on the membrane surface. After the gas molecules dissolve into the membrane, they diffuse in the membrane. Due to the concentration gradient in the membrane, the gas molecules diffuse from the high concentration side to the low concentration side. The molecular kinetic diameters of nitrogen and oxygen are different (the molecular kinetic diameter of nitrogen is about 0.364nm, and that of oxygen is about 0.346nm), and their interactions with the molecular segments in the membrane are different, resulting in different diffusion rates in the membrane. When the mixed gas enters the hollow fiber membrane separation system, the separation of oxygen and nitrogen is achieved due to their different solubility and diffusion characteristics in the membrane. In the prior art, conventional hollow fiber membranes have low separation efficiency and slow separation speed for oxygen and nitrogen, which greatly restricts the large-scale application of nitrogen-oxygen separation technology. Summary of the invention

[0004] The present invention aims to provide a hollow fiber composite matrix membrane to address the technical defects of the prior art, so as to solve the technical problems of low separation efficiency and slow separation speed of conventional hollow fiber membranes for oxygen and nitrogen.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: A hollow fiber composite matrix membrane is prepared by the following method: 1) Dissolve MOFs in N,N-dimethylformamide, mix evenly, add bis(4-aminophenyl) ether thereto, add hexafluorodianhydride after dissolution, and react for a certain time; add triethylamine and acetic anhydride thereto, continue to react for a period of time, add Tween-80 to the reaction product, stir evenly, filter and degas in sequence to obtain a casting solution; the duration of the certain reaction time is 3-4 hours; the duration of the reaction period is 2-3 hours; 2) adding N-methyl-2-pyrrolidone to ethanol and mixing well, then adding polyethylene glycol-400 thereto and mixing well to obtain a core liquid; 3) The casting solution obtained in step 1) and the core solution obtained in step 2) are co-extruded from the spinning head of a hollow fiber membrane spinning machine to obtain fiber membrane filaments; the fiber membrane filaments are water-bathed in pure water at 30-40°C; pure water and N-methylpyrrolidone are mixed in a ratio of 1:8-9 to obtain a mixed solvent, and the water-bathed fiber membrane filaments are solvent-bathed in the mixed solvent at 35-45°C; and then rinsed to obtain the hollow fiber composite matrix membrane.

[0006] Preferably, in step 1), the mass volume ratio of MOFs and N,N-dimethylformamide is 0.3-0.5 g:90-110 mL.

[0007] Preferably, in step 1), the mass ratio of MOFs to bis(4-aminophenyl) ether and hexafluorodianhydride is 0.3-0.5 g: 1.5-2.2 g: 1.1-1.6 g.

[0008] Preferably, in step 1), the mass ratio of MOFs to triethylamine and acetic anhydride is 0.3-0.5 g: 0.05-0.1 g: 0.6-0.9 g.

[0009] Preferably, in step 1), during the reaction for a certain time and a period of time, the system is protected by an inert gas, and the reaction process is carried out under continuous stirring at a stirring speed of 300-400 rpm.

[0010] Preferably, in step 1), the mass volume ratio of MOFs to Tween-80 is 0.3-0.5 g:8-10 mL.

[0011] Preferably, the pore size of the filter in step 1) is 0.5-1 mm; the degassing is carried out in an environment of 0.2-0.3 atmospheres with stirring for 30-60 minutes.

[0012] Preferably, in step 2), the volume ratio of N-methyl-2-pyrrolidone, ethanol and polyethylene glycol-400 is 20-30 mL: 60-70 mL: 10-15 mL.

[0013] Preferably, in step 3), the water bath duration is 5 to 10 minutes; and the solvent bath duration is 20 to 30 seconds.

[0014] Preferably, the rinsing in step 3) is performed with pure water at 20-25° C., and the number of rinsing is 3-5 times.

[0015] The present invention provides a hollow fiber composite matrix membrane. The technical solution uses MOFs as a crystalline porous material and uses it as a metal skeleton. The inorganic metal center and the bridging organic ligand self-assemble to form a periodic network structure; on this basis, a polymerization reaction is carried out with bis(4-aminophenyl) ether and hexafluorodianhydride, and then an imine condensation reaction is carried out with acetic anhydride under the catalysis of triethylamine to obtain a composite matrix casting liquid; the composite matrix membrane obtained from the casting liquid has a surface macroporous structure and an internal support structure, which can significantly improve the nitrogen and oxygen separation efficiency. The present invention uses N-methyl-2-pyrrolidone, ethanol and polyethylene glycol to construct the core liquid; for the fiber membrane filaments obtained by extrusion, they are modified with an organic solvent after coagulation in a water bath, and finally rinsed to obtain the finished product. The hollow fiber composite matrix membrane of the present invention has good selectivity for nitrogen and oxygen molecules and a fast separation speed, which can greatly improve the separation efficiency of nitrogen and oxygen in the air, and is particularly suitable for industrial-scale nitrogen and oxygen separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a scanning electron microscope image of a cross section of the hollow fiber composite matrix membrane prepared in Example 1 of the present invention.

[0017] Figure 2 This is a partial scanning electron microscope image of the cross section of the hollow fiber composite matrix membrane prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. In addition, ordinary technicians in this field know that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0019] In the description of the present application, it should be understood that, unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as those commonly understood by those skilled in the art of the present application. In addition, any terminology used is only for the purpose of describing specific embodiments and is not intended to limit the present application.

[0020] In addition, in order to better illustrate the present application, many specific details are given in the following specific embodiments. Those skilled in the art should understand that the present application can also be implemented without certain specific details.

[0021] Table 1 Reagent list Element source MOFs Ruixi Biological N,N-Dimethylformamide Sigma Bis(4-aminophenyl)ether Alfa Chemistry Hexafluorodianhydride Shanghai Zhongwei Chemical Co., Ltd. Triethylamine CNW, Germany Acetic anhydride Shanghai Zhongwei Chemical Co., Ltd. Twain-80 Sigma N-Methyl-2-pyrrolidone Sigma Polyethylene glycol-400 Hunan Yunbang Biotechnology Co., Ltd. N-Methylpyrrolidone Sigma Example 1

[0022] A hollow fiber composite matrix membrane is prepared by the following method: 1) Dissolve 0.4g MOFs in 105mL N,N-dimethylformamide, mix well, add 1.7g bis(4-aminophenyl) ether, add 1.4g hexafluorodianhydride after dissolution, and react for 3.2h; add 0.08g triethylamine and 0.7g acetic anhydride, continue to react for 2.5h, add 9mL Tween-80 to the reaction product, stir well, filter and degas in turn to obtain a casting solution; 2) Add 25 mL of N-methyl-2-pyrrolidone to 68 mL of ethanol and mix well. Then add 12 mL of polyethylene glycol-400 and mix well to obtain the core solution.

[0023] 3) The casting solution obtained in step 1) and the core solution obtained in step 2) are co-extruded from the spinning head of a hollow fiber membrane spinning machine to obtain fiber membrane filaments; the fiber membrane filaments are bathed in pure water at 35°C for 9 minutes; pure water and N-methylpyrrolidone are mixed in a ratio of 1:8.7 to obtain a mixed solvent, and the fiber membrane filaments after the water bath are bathed in the mixed solvent at 40°C for 23 seconds; and then rinsed with pure water at 22°C for 4 times to obtain the hollow fiber composite matrix membrane.

[0024] In step 1), during the reaction for a certain time and a period of time, the system is protected by an inert gas, and the reaction process is carried out under continuous stirring at a stirring speed of 300-400 rpm. The pore size of the filtration in step 1) is 0.5 mm; the degassing is maintained for 40 minutes in a stirring state in an environment of 0.25 atmospheres.

[0025] Membrane flux detection method: The membrane permeation selectivity performance test system was used to test the permeation flux of the membrane to O2 and N2. The test system included a pump, membrane tank, pipeline, regulating valve, pressure and soap film flowmeter. The effective membrane area tested was 5.12cm 2 , the test pressure is 1~5bar, and the test temperature is 22±1℃.

[0026] The calculation formula of gas permeation rate is: R i =Q i / (A·△P i ), where Ri is the penetration rate of component i, in GPU (1 GPU = 10 -6 cm 3 (STP) cm -2 ·s -1 cmHg -1 ), Q i is the volume flow rate of component i at standard temperature and pressure (STP), in cm 3 (STP) / s; ΔP i For components i The partial pressure difference on both sides of the membrane, unit is cmHg; A is the effective membrane area, unit is cm 2 .

[0027] The selectivity of separation membranes is often evaluated by separation selectivity, i.e., separation factor (α). Commonly used separation factors include ideal separation factor and true separation factor.

[0028] When pure gas is used for testing, the ideal separation factor α of components i and j is * i / j The definition is: α * i / j =R i / R j In the formula, R i and R j are the permeation rates of components i and j, respectively.

[0029] For a gas mixture containing two components i and j, the true separation factor α ' i / j The definition is: α ' i / j =(y i / y j ) / (x i / x j ) In the formula, y i ,y j are the mole fractions of components i and j in the permeate gas respectively; x i 、x j are the mole fractions of components i and j in the feed gas, respectively.

[0030] After testing, the O2 permeation rate of the hollow fiber composite matrix membrane in this embodiment reaches 2200 GPU, and the O2 / N2 separation factor is 32. Example 2

[0031] A hollow fiber composite matrix membrane is prepared by the following method: 1) Dissolve 0.3g MOFs in 90mL N,N-dimethylformamide, mix well, add 1.5g bis(4-aminophenyl) ether, add 1.1g hexafluorodianhydride after dissolution, and react for 3h; add 0.05g triethylamine and 0.6g acetic anhydride, continue to react for 2h, add 8mL Tween-80 to the reaction product, stir well, filter and degas in sequence to obtain a casting solution; 2) Add 20 mL of N-methyl-2-pyrrolidone to 60 mL of ethanol and mix well, then add 10 mL of polyethylene glycol-400 and mix well to obtain the core liquid.

[0032] 3) The casting solution obtained in step 1) and the core solution obtained in step 2) are co-extruded from the spinning head of a hollow fiber membrane spinning machine to obtain fiber membrane filaments; the fiber membrane filaments are bathed in pure water at 30°C for 5 minutes; pure water and N-methylpyrrolidone are mixed in a ratio of 1:8 to obtain a mixed solvent, and the fiber membrane filaments after the water bath are bathed in the mixed solvent at 35°C for 20 seconds; and then rinsed with pure water at 20°C for 3 times to obtain the hollow fiber composite matrix membrane.

[0033] In step 1), during the reaction for a certain time and a period of time, the system is under the protection of inert gas, and the reaction process is carried out under continuous stirring at a stirring speed of 300-400 rpm. The pore size of the filtration in step 1) is 0.5 mm; the degassing is maintained in a stirring state for 30 minutes in an environment of 0.2 atmospheres. According to the test, the O2 permeation rate of the hollow fiber composite matrix membrane in this embodiment reaches 1800 GPU, and the O2 / N2 separation factor is 35. Example 3

[0034] A hollow fiber composite matrix membrane is prepared by the following method: 1) Dissolve 0.5g MOFs in 110mL N,N-dimethylformamide, mix well, add 2.2g bis(4-aminophenyl) ether, add 1.6g hexafluorodianhydride after dissolution, and react for 4h; add 0.1g triethylamine and 0.9g acetic anhydride, continue to react for 3h, add 10mL Tween-80 to the reaction product, stir well, filter and degas in turn to obtain a casting solution; 2) Add 30 mL of N-methyl-2-pyrrolidone into 70 mL of ethanol and mix well. Then add 15 mL of polyethylene glycol-400 and mix well to obtain the core solution.

[0035] 3) The casting solution obtained in step 1) and the core solution obtained in step 2) are co-extruded from the spinning head of a hollow fiber membrane spinning machine to obtain fiber membrane filaments; the fiber membrane filaments are bathed in pure water at 40°C for 10 minutes; pure water and N-methylpyrrolidone are mixed in a ratio of 1:9 to obtain a mixed solvent, and the bathed fiber membrane filaments are bathed in the mixed solvent at 45°C for 30 seconds; and then rinsed with pure water at 25°C for 5 times to obtain the hollow fiber composite matrix membrane.

[0036] In step 1), during the reaction for a certain time and a period of time, the system is under the protection of an inert gas, and the reaction process is carried out under continuous stirring at a stirring speed of 300-400 rpm. The pore size of the filtration in step 1) is 1 mm; the degassing is maintained for 60 min in a stirring state in an environment of 0.3 atmospheres. After testing, the O2 permeation rate of the hollow fiber composite matrix membrane in this embodiment reaches 1700 GPU, and the O2 / N2 separation factor is 33. The above experimental results show that the present invention can significantly improve the separation efficiency of oxygen and nitrogen by the membrane separation method, and at the same time, the separation speed is also improved to a certain extent. Moreover, the present invention has good structural stability and is expected to be applied on a large scale.

[0037] In summary, after reading this detailed disclosure, it will be apparent to those skilled in the art that the aforementioned detailed disclosure may be presented only by way of example and may not be restrictive. Although not explicitly stated herein, it will be appreciated by those skilled in the art that this application is intended to encompass various reasonable changes, improvements and modifications to the embodiments. These changes, improvements and modifications are intended to be proposed by this application and are within the spirit and scope of the exemplary embodiments of this application.

[0038] It should be understood that in the foregoing description of the embodiments of the present application, in order to help understand a feature and to simplify the present application, the present application combines various features in a single embodiment, drawing or description thereof. However, this does not mean that the combination of these features is necessary, and it is entirely possible for those skilled in the art to extract some of the features and understand them as separate embodiments when reading the present application.

[0039] It should be understood that the embodiments disclosed herein are illustrations of the principles of the present application. Other modified embodiments are also within the scope of the present application. The embodiments disclosed herein are merely examples and not limitations, and the embodiments of the present application are not limited to the embodiments precisely described above.

Claims

1. A hollow fiber composite matrix membrane, characterized in that: It is prepared by the following method: 1) Dissolve MOFs in N,N-dimethylformamide, mix evenly, add bis(4-aminophenyl) ether thereto, add hexafluorodianhydride after dissolution, and react for a certain time; add triethylamine and acetic anhydride thereto, continue to react for a period of time, add Tween-80 to the reaction product, stir evenly, filter and degas in sequence to obtain a casting solution; the duration of the certain reaction time is 3-4 hours; the duration of the reaction period is 2-3 hours; 2) adding N-methyl-2-pyrrolidone to ethanol and mixing well, then adding polyethylene glycol-400 thereto and mixing well to obtain a core liquid; 3) The casting solution obtained in step 1) and the core solution obtained in step 2) are co-extruded from the spinning head of a hollow fiber membrane spinning machine to obtain fiber membrane filaments; the fiber membrane filaments are water-bathed in pure water at 30-40°C; pure water and N-methylpyrrolidone are mixed in a ratio of 1:8-9 to obtain a mixed solvent, and the water-bathed fiber membrane filaments are solvent-bathed in the mixed solvent at 35-45°C; and then rinsed to obtain the hollow fiber composite matrix membrane.

2. A hollow fiber composite matrix membrane according to claim 1, characterized in that: In step 1), the mass volume ratio of MOFs and N,N-dimethylformamide is 0.3~0.5g:90~110mL.

3. A hollow fiber composite matrix membrane according to claim 1, characterized in that: In step 1), the mass ratio of MOFs to bis(4-aminophenyl) ether and hexafluorodianhydride is 0.3~0.5g:1.5~2.2g:1.1~1.6g.

4. A hollow fiber composite matrix membrane according to claim 1, characterized in that: In step 1), the mass ratio of MOFs to triethylamine and acetic anhydride is 0.3~0.5g:0.05~0.1g:0.6~0.9g.

5. The hollow fiber composite matrix membrane according to claim 1, characterized in that: In step 1), during the reaction for a certain time and a period of time, the system is protected by an inert gas and the reaction is carried out under continuous stirring at a stirring speed of 300-400 rpm.

6. The hollow fiber composite matrix membrane according to claim 1, characterized in that: In step 1), the mass volume ratio of MOFs and Tween-80 is 0.3~0.5g:8~10mL.

7. The hollow fiber composite matrix membrane according to claim 1, characterized in that: The pore size of the filtration in step 1) is 0.5-1 mm; the degassing is carried out in an environment of 0.2-0.3 atmospheres with stirring for 30-60 minutes.

8. The hollow fiber composite matrix membrane according to claim 1, characterized in that: In step 2), the volume ratio of N-methyl-2-pyrrolidone, ethanol and polyethylene glycol-400 is 20~30 mL: 60~70 mL: 10~15 mL.

9. The hollow fiber composite matrix membrane according to claim 1, characterized in that: In step 3), the water bath duration is 5 to 10 minutes; the solvent bath duration is 20 to 30 seconds.

10. The hollow fiber composite matrix membrane according to claim 1, characterized in that: The rinsing in step 3) is performed with pure water at 20-25° C., and the number of rinsing times is 3-5 times.

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