Metal ion functionalized polyimide gas separation membrane as well as preparation method and application thereof

Abstract

The invention discloses a metal ion functionalized polyimide gas separation membrane as well as a preparation method and application thereof. The metal ion functionalized polyimide gas separation membrane is prepared from a diamine monomer and a dianhydride monomer, the diamine monomer at least comprises a diamine monomer containing metal coordination ions; the diamine monomer containing the metal coordination ions is one or two of diamino ferrocene, diamino chromium dicyclopentadienyl, diamino nickel dicyclopentadienyl and diamino cobalt dicyclopentadienyl. According to the metal ion functionalized polyimide gas separation membrane disclosed by the invention, diamine monomers containing metal coordination ions are polymerized, so that metal ions can be introduced into a polyimide structure, and polyimide molecular chains in a membrane material can be relatively loosely arranged by utilizing the volume effect of the metal ions; therefore, the free volume of the membrane material is effectively increased, and finally the gas permeability of the membrane material can be effectively improved. In addition, the permeability and selectivity of target separated gas can be directionally improved by introducing different metal ions, so that the method is used for enrichment of industrial oxygen and purification and separation of hydrogen.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyimide gas separation membranes, and in particular relates to a metal ion functionalized polyimide gas separation membrane and a preparation method and application thereof. Background Art

[0002] With the continuous advancement and development of science and technology, gas separation and purification are becoming increasingly important in industrial production and have become an indispensable component in many industrial production areas. For example, in the environmental protection field, many industrial production processes generate large amounts of polluting mixed gases that are harmful to the environment. These mixed gases contain large amounts of pollutants such as methane, carbon dioxide, sulfur dioxide, and nitrogen dioxide. Further separation is required to remove these harmful pollutants and ensure that they meet environmental emission standards. In the energy sector, for example, during the extraction and transportation of natural gas, deacidification treatment is required to separate and remove impurities such as nitrogen, carbon dioxide, and sulfur dioxide from the extracted natural gas. This not only increases the concentration of natural gas to meet industrial and domestic usage standards, but also prevents these acidic gases from causing acidic corrosion damage to natural gas transmission pipelines, ensuring the safety of natural gas transportation, extending the service life of transportation pipelines, and reducing natural gas transportation costs. Furthermore, many industrial production processes require high-purity gases, and the production of these high-purity gases involves gas separation and purification processes. Traditional gas separation and purification technologies mainly rely on cryogenic separation or chemical adsorption. Although these technologies are relatively mature, they have disadvantages such as high production investment costs, high energy consumption, and complex operations. The use of gas separation membrane technology for gas separation and purification can not only significantly reduce energy consumption, but also has low production costs and is relatively simple, safe, and reliable to operate.

[0003] As a special polymer material, polyimide has many advantages such as high temperature resistance, solvent resistance, high strength, a wide variety, and easy structural adjustment. Due to the different molecular chain structures, it has different separation effects for different gases and has always been regarded as the best material for gas separation membranes.

[0004] However, existing polyimide gas separation membranes are mostly focused on pure polyimide membrane materials, and research on their modification has also largely focused on doping and composite modification technologies. For example, Chinese patent document CN113289506A discloses an asymmetric magnetic oxygen-nitrogen separation membrane and its preparation method. The method involves dispersing magnetic particles in a solvent to obtain a magnetic particle dispersion, adding a polymer, and stirring to obtain a casting solution, ultimately producing an asymmetric magnetic oxygen-nitrogen separation membrane. On the one hand, this co-doping modification method has limited improvement in the gas separation performance of the membrane material. On the other hand, because magnetic fillers are prone to agglomeration, this can result in uneven filler distribution or large-particle filler agglomeration defects, leading to low membrane material yield, uneven performance, and poor repeatability. Summary of the Invention

[0005] The purpose of the present invention is to solve the above problems and provide a metal ion functionalized polyimide gas separation membrane having not only good gas separation performance but also uniform membrane material performance and good repeatability, as well as a preparation method and application thereof.

[0006] The technical solution for achieving the purpose of the present invention is: a metal ion functionalized polyimide gas separation membrane, which is made of diamine monomers and dianhydride monomers; the diamine monomers at least include diamine monomers containing metal coordination ions.

[0007] The diamine monomer also includes a diamine monomer that does not contain a metal coordination ion.

[0008] The molar percentage of the diamine monomer containing metal coordination ions in the diamine monomer is 10% to 100%.

[0009] The molar ratio of the diamine monomer to the dianhydride monomer is 1:0.95 to 1:1.05.

[0010] The polyimide structure in the metal ion functionalized polyimide gas separation membrane of the present invention is as follows: .

[0011] Wherein: m is an integer, and n is a positive integer.

[0012] A is one or two of the following dianhydride structures: 、 、 、 、 .

[0013] That is, the dianhydride monomer is one or two of hexafluorodianhydride (6FDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-oxydiphthalic anhydride (ODPA), pyromellitic dianhydride (PMDA), and 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA).

[0014] B is one or two of iron ion, chromium ion, nickel ion and cobalt ion.

[0015] That is, the diamine monomer containing a metal coordination ion is one or two of diaminoferrocene, diaminochromocene, diaminonickelocene, and diaminocobaltocene.

[0016] C is one or two of the following diamine structures: 、 、 、 、 、 .

[0017] That is, the diamine monomer containing no metal coordination ions is one or two of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 2,2'-dimethyl-4,4'-diaminobiphenyl (mTD), tetramethyl-p-phenylenediamine (TMPD), 2,6-diaminotoluene (2,6-TDA), 2,4,6-trimethyl-1,3-phenylenediamine (TrMPD), and m-phenylenediamine (mPD).

[0018] The method for preparing the metal ion functionalized polyimide gas separation membrane comprises the following steps: S1. Prepare polyimide resin.

[0019] S2. Preparation of metal ion functionalized polyimide gas separation membrane.

[0020] The specific method of the above step S1 is as follows: S11, diamine monomer and dianhydride monomer are polymerized in an organic solvent to obtain polyamic acid slurry.

[0021] S12, adding a catalyst and a dehydrating agent to the polyamic acid slurry obtained in step S11, and obtaining a polyimide slurry through an imidization reaction.

[0022] S13, injecting the polyimide slurry obtained in step S12 into the phase conversion liquid to obtain a filamentous solid, then repeatedly washing the filamentous solid with the phase conversion liquid, and finally drying to obtain a polyimide resin.

[0023] In the above step S11, the molar ratio of the diamine monomer to the dianhydride monomer is 1:0.95 to 1:1.05.

[0024] In the above step S11, the organic solvent is one of N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and 1,3-dimethyl-2-imidazolidinone (DMI).

[0025] In the above step S11, the polymerization reaction temperature is 0-10° C. and the time is 5-10 h.

[0026] In the above step S12, the catalyst is one of pyridine, picoline, and triethylamine, preferably pyridine.

[0027] In the above step S12, the dehydrating agent is one of acetic anhydride and propionic anhydride, preferably acetic anhydride.

[0028] In the above step S12, the molar amount of the dehydrating agent is 2 to 4 times that of the dianhydride monomer in step S11.

[0029] In the above step S12, the molar ratio of the dehydrating agent to the catalyst is 1:0.5 to 1:2, preferably 1:1.

[0030] In the above step S12, the imidization reaction temperature is 20-40° C. and the time is 5-10 hours.

[0031] In the above step S12, the solid content of the polyimide slurry is 10-30 wt%.

[0032] In the above step S13, the phase conversion liquid is one of methanol, ethanol and deionized water.

[0033] The specific method of the above step S2 is as follows: S21, adding the polyimide resin obtained in step S1 into an organic solvent, stirring and dissolving to obtain a casting solution.

[0034] S22. The casting solution obtained in step S2 is evenly coated on a clean glass plate, and then placed in an oven, programmed to remove the solvent by temperature increase, and then naturally cooled to room temperature. The film-coated glass plate is immersed in distilled water for peeling to obtain a metal ion functionalized polyimide gas separation membrane.

[0035] In the above step S21, the organic solvent is one of N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and 1,3-dimethyl-2-imidazolidinone (DMI).

[0036] In the above step S21 , the weight ratio of the polyimide resin to the organic solvent is 1:9 to 3:7; that is, the solid content of the casting solution is 10 to 30 wt %.

[0037] The thickness of the metal ion functionalized polyimide gas separation membrane of the present invention can be adjusted by adjusting the solid content of the casting solution, and can also be adjusted by adjusting the opening height of the scraper.

[0038] The metal ion functionalized polyimide gas separation membrane of the invention is used for enriching industrial oxygen and purifying and separating hydrogen.

[0039] The present invention has the positive effects: (1) The metal ion functionalized polyimide gas separation membrane of the present invention is polymerized using a diamine monomer containing a metal coordination ion, which can introduce metal ions into the polyimide structure. The volume effect of the metal ions can make the polyimide molecular chains inside the membrane material relatively loose, thereby effectively increasing the free volume of the membrane material and ultimately effectively improving the gas permeability of the membrane material.

[0040] (2) The metal ion functionalized polyimide gas separation membrane of the present invention utilizes the specific adsorption of different metal ions to different gases to improve the permeability and selectivity of the target separated gas. By introducing iron ions, the O2 gas permeability (≥140 Barrer) and O2 / N2 gas selectivity (≥9) can be greatly improved. By introducing nickel, chromium, cobalt and other ions, the H2 gas permeability (≥300 Barrer) and H2 / N2 gas selectivity (≥30) can be greatly improved. Thus, it can be used in the fields of industrial oxygen enrichment, hydrogen purification and separation.

[0041] (3) The preparation method of the metal ion functionalized polyimide gas separation membrane of the present invention is different from the mixed matrix membrane prepared by the doping method. The metal ions are embedded in the polyimide molecular chain in the form of monomers and are very evenly distributed, which can form a homogeneous membrane material and effectively avoid the disadvantages of high membrane material defects and poor repeatability of the mixed matrix membrane prepared by the doping method. DETAILED DESCRIPTION

[0042] (Example 1) The preparation method of the metal ion functionalized polyimide gas separation membrane of this embodiment comprises the following steps: S1. Prepare polyimide resin.

[0043] S11. Add 500 mL of N,N-dimethylacetamide (DMAc), 22.0170 g of diaminoferrocene and 12.4488 g of 2,6-diaminotoluene (2,6-TDA) to the reaction device, stir and dissolve at 30°C, then cool to 5°C, add 90.5341 g of hexafluorodianhydride (6FDA), control the temperature at 5°C and carry out polymerization reaction for 8 hours to obtain polyamic acid slurry.

[0044] S12. Add 48 g of pyridine and 62 g of acetic anhydride to the reaction apparatus, control the temperature at 35° C. to carry out imidization reaction for 8 h, and obtain a polyimide slurry with a solid content of 20 wt %.

[0045] S13. Inject the polyimide slurry obtained in step S12 into 500 mL of methanol to obtain a filamentous solid, and then repeatedly wash the filamentous solid with methanol (500 mL×3). After washing, first dry it naturally in a dark and dry environment for 5 hours, then place it in an oven, first vacuum dry it at 80°C for 4 hours, then heat it to 160°C and vacuum dry it for 1 hour, and finally heat it to 220°C and vacuum dry it for 2 hours to obtain a polyimide resin.

[0046] S2. Preparation of metal ion functionalized polyimide gas separation membrane.

[0047] S21. Add 20 g of the polyimide resin obtained in step S1 into a flask, then add 80 g of DMAc solvent, and stir and dissolve at room temperature for 4 h to obtain a casting solution with a solid content of 20 wt%.

[0048] S22. The casting liquid is evenly coated on a clean glass plate, and then placed in an oven, and the temperature is programmed to remove the solvent [80°C for 4 hours, 160°C for 2 hours, and 200°C for 2 hours]. Then the temperature is naturally lowered to room temperature, and the film-coated glass plate is immersed in distilled water for peeling to obtain a metal ion functionalized polyimide gas separation membrane.

[0049] (Example 2 to Example 8) Each embodiment is basically the same as embodiment 1, except for step S11 and step S12, as shown in Table 1.

[0050] (Comparative Examples 1 to 4) Each comparative example is basically the same as Example 1, except for step S11 and step S12, as shown in Table 1.

[0051] Table 1 Diamine monomers containing metal ions Metal ion-free diamine monomer Dianhydride monomer Pyridine Acetic anhydride Example 1 22.0170 g of diaminoferrocene 12.4488 g of 2,6-TDA 90.5341g of 6FDA 48g 62g Example 2 18.9564 g of diaminoferrocene 28.0947g of TFMB 77.9489g of 6FDA 42g 53g Example 3 21.2868 g of diaminoferrocene 16.1816 g of TMPD 87.5315g of 6FDA 47g 62g Example 4 40.9031 g of diaminoferrocene —— 84.0969g of 6FDA 45g 58g Example 5 21.7788 g of diaminocobaltocene 14.9286 g of TrMPD 88.2956g of 6FDA 48g 62g Example 6 19.5824 g of diaminochromocene 20.3351g of mTD 85.1067g of 6FDA 45g 58g Example 7 18.5687g of nickelocene diaminodiphenylamine 28.1973g of TFMB 78.2339g of 6FDA 41g 53g Example 8 50.5834 g of nickelocene diaminodiphenylamine —— 74.4167g of ODPA 56g 73g Comparative Example 1 —— 52.3614g of TFMB 72.6386g of 6FDA 39g 50g Comparative Example 2 —— 29.1551 g of TFMB and 14.9540 g of TMPD 80.8909g of 6FDA 43g 56g Comparative Example 3 —— 52.3904g mTD 72.6096g of BPDA 58g 75g Comparative Example 4 —— 27.9050 g of mTD and 19.7460 g of TrMPD 77.3489g of BPDA 62g 80g

[0052] (Test example) The gas permeability of the polyimide gas separation membranes prepared in each embodiment and each comparative example was tested. The results are shown in Table 2.

[0053] The test conditions for gas permeability coefficient are 25°C and 0.20 MPa, and the unit is Barrer.

[0054] Table 2 <![CDATA[H2]]> <![CDATA[CO2]]> <![CDATA[O2]]> <![CDATA[N2]]> <![CDATA[H2 / N2]]> <![CDATA[CO2 / N2]]> <![CDATA[O2 / N2]]> Example 1 174.44 96.23 147.13 8.38 20.82 11.48 17.56 Example 2 181.43 108.43 161.58 10.03 18.09 10.81 16.11 Example 3 211.43 119.64 182.57 20.11 10.51 5.95 9.08 Example 4 206.89 135.87 172.26 19.01 10.88 7.15 9.06 Example 5 344.38 202.13 89.42 20.20 17.05 10.01 4.43 Example 6 367.88 125.38 55.52 11.03 33.35 11.37 5.03 Example 7 381.57 127.63 76.38 11.28 33.83 11.31 6.77 Example 8 293.54 112.01 60.83 11.12 26.40 10.07 5.47 Comparative Example 1 121.44 74.15 19.81 9.56 12.70 7.76 2.07 Comparative Example 2 184.15 97.56 28.33 13.48 13.66 7.24 2.10 Comparative Example 3 53.13 31.24 16.88 4.14 12.83 7.55 4.08 Comparative Example 4 84.46 52.17 28.43 8.31 10.16 6.28 3.42

Claims

1. A metal ion functionalized polyimide gas separation membrane, which is made of diamine monomers and dianhydride monomers; characterized in that: The diamine monomers at least include diamine monomers containing metal coordination ions; the diamine monomers containing metal coordination ions are one or two of diaminoferrocene, diaminochromocene, diaminonickelocene, and diaminocobaltocene; the molar percentage of the diamine monomers containing metal coordination ions in the diamine monomers is 10% to 100%.

2. The metal ion functionalized polyimide gas separation membrane according to claim 1, characterized in that: The diamine monomer also includes a diamine monomer that does not contain a metal coordination ion; the diamine monomer that does not contain a metal coordination ion is one or two of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, tetramethyl-p-phenylenediamine, 2,6-diaminotoluene, 2,4,6-trimethyl-1,3-phenylenediamine, and m-phenylenediamine.

3. The metal ion functionalized polyimide gas separation membrane according to claim 1, characterized in that: The dianhydride monomer is one or two of hexafluorodianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, pyromellitic dianhydride, and 3,3',4,4'-benzophenonetetracarboxylic dianhydride.

4. A method for preparing a metal ion functionalized polyimide gas separation membrane according to any one of claims 1 to 3, characterized in that The following steps are involved: S1. Prepare polyimide resin; the specific method is as follows: S11, diamine monomer and dianhydride monomer are polymerized in an organic solvent to obtain polyamic acid slurry; S12, adding a catalyst and a dehydrating agent to the polyamic acid slurry obtained in step S11, and obtaining a polyimide slurry through an imidization reaction; S13, injecting the polyimide slurry obtained in step S12 into the phase conversion liquid to obtain a filamentous solid, then repeatedly washing the filamentous solid with the phase conversion liquid, and finally drying to obtain a polyimide resin; S2. Preparation of metal ion functionalized polyimide gas separation membrane; the specific method is as follows: S21, adding the polyimide resin obtained in step S1 into an organic solvent, stirring and dissolving to obtain a casting solution; S22. The casting solution obtained in step S2 is uniformly coated on a clean glass plate, and then placed in an oven, and the temperature is programmed to remove the solvent, and then naturally cooled to room temperature. The glass plate with the membrane is immersed in distilled water for peeling, and a metal ion functionalized polyimide gas separation membrane is obtained.

5. The method for preparing a metal ion functionalized polyimide gas separation membrane according to claim 4, characterized in that: In the above step S11, the molar ratio of the diamine monomer to the dianhydride monomer is 1:0.95 to 1:1.05; the organic solvent is one of N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, and 1,3-dimethyl-2-imidazolidinone; the polymerization reaction temperature is 0 to 10°C, and the time is 5 to 10 hours.

6. The method for preparing a metal ion functionalized polyimide gas separation membrane according to claim 4, characterized in that: In the above step S12, the catalyst is one of pyridine, picoline, and triethylamine; the dehydrating agent is one of acetic anhydride and propionic anhydride; the molar amount of the dehydrating agent is 2 to 4 times that of the dianhydride monomer in step S11; the molar ratio of the dehydrating agent to the catalyst is 1:0.5 to 1:2; the imidization reaction temperature is 20 to 40°C, and the time is 5 to 10 hours; the solid content of the polyimide slurry is 10 to 30wt%.

7. The method for preparing a metal ion functionalized polyimide gas separation membrane according to claim 4, characterized in that: In the above step S13, the phase conversion liquid is one of methanol, ethanol and deionized water.

8. The method for preparing a metal ion functionalized polyimide gas separation membrane according to claim 4, characterized in that: In the above step S21, the organic solvent is one of N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidone, and 1,3-dimethyl-2-imidazolidinone; and the weight ratio of the polyimide resin to the organic solvent is 1:9 to 3:

7.

9. Use of the metal ion functionalized polyimide gas separation membrane according to any one of claims 1 to 3 in industrial oxygen enrichment and hydrogen purification and separation.