Preparation method of metal hybrid gas separation carbon membrane material

Abstract

The invention relates to a preparation method of a metal hybrid gas separation carbon membrane material, and belongs to the field of gas separation membranes and the field of new materials. A preparation method of a metal hybrid gas separation carbon membrane material comprises the following steps: dispersing a metal salt or a metal organic complex in a polar organic solvent, and then adding a diamine monomer with a coordination group into the dispersion liquid to form a metal-diamine complex solution; reacting the metal-diamine complex solution with a dianhydride monomer, cooling to room temperature to obtain a metal-containing polyamide acid solution, preparing a membrane casting solution, enabling the membrane casting solution to form a membrane at room temperature, and drying to obtain a metal-containing polyamide acid polymer membrane; and carbonizing the obtained metal-containing polyamide acid polymer membrane to obtain the metal hybrid gas separation carbon membrane. Compared with the prior art, the preparation method provided by the invention has the advantages that the metal is synthesized into the carbon film precursor in an in-situ matching manner, so that the interfacial compatibility between the metal and the polymer is enhanced, and the generation of non-selective defects is reduced.

Description

Technical Field

[0001] The invention relates to a method for preparing a metal hybrid gas separation carbon membrane material, and belongs to the field of gas separation membranes and new materials. Background Art

[0002] As the third generation of gas separation technology, membrane separation technology has the advantages of low energy consumption, no pollution, low cost, and easy coupling with other chemical units compared with traditional gas separation technology. It has been widely used in the fields of hydrogen enrichment and natural gas purification. Currently, the commonly used commercial gas separation membrane materials are mainly polymer membrane materials. Polymer membranes usually have high gas separation selectivity, but the gas permeability is generally poor. In addition, polymer membrane materials also have disadvantages such as not being resistant to high temperatures, not being resistant to chemical corrosion, and being easy to plasticize, which makes it difficult to meet the growing industrial needs. Therefore, the development of new membrane materials and the improvement of the permeability and separation selectivity of membrane materials are currently research hotspots in the field of membrane technology.

[0003] Carbon membrane is a high-performance carbon-based porous membrane material prepared by high-temperature pyrolysis of carbon-containing materials in an inert atmosphere or vacuum environment. It has the advantages of good thermal and chemical stability and adjustable membrane pore structure. The unique bimodal pore size distribution can effectively separate gases with similar molecular sizes. However, due to the influence of the worm-like pore structure of the carbon membrane, the gas permeability of the carbon membrane is often poor. To solve this problem, nanoparticles with regular pore structures or certain functions are added to the carbon membrane precursor to adjust the gas permeation path of the carbon membrane and achieve high permeability and selectivity of the carbon membrane. Among them, adding metals that promote gas transmission to the carbon membrane precursor can effectively improve the gas permeability of the carbon membrane. However, due to the high surface energy of nanomaterials, metal nanoparticles are prone to agglomeration in the carbon membrane precursor solution, forming non-selective defects and reducing the gas separation selectivity. Therefore, how to evenly disperse the metal in the carbon membrane matrix, improve the degree of metal dispersion, and reduce the non-selective defects caused by agglomeration and other problems is the key to preparing defect-free metal carbon membranes and achieving efficient gas separation. Summary of the invention

[0004] In order to solve the above problems, the present invention introduces metals such as Cu, Pt, Ni, etc. that have a certain promoting effect on gas transmission into the carbon membrane precursor. The metal salt / metal organic complex is chelated with a diamine monomer with a coordination group to form a metal-diamine complex, and then a polyamic acid solution containing a metal is synthesized with a dianhydride monomer to prepare a carbon membrane, thereby improving the separation ability of hydrogen. Compared with traditional technologies, the metal is synthesized into a carbon membrane precursor in an in-situ coordination manner, which enhances the interfacial compatibility between the metal and the polymer and reduces the generation of non-selective defects.

[0005] A method for preparing a metal hybrid gas separation carbon membrane material comprises the following steps:

[0006] Step 1: Disperse a metal salt or a metal-organic complex in a polar organic solvent, and then add a diamine monomer having a coordination group to the dispersion. React at a certain temperature for a certain period of time to form a metal-diamine complex solution;

[0007] Step 2: React the metal-diamine complex solution with a dianhydride monomer at a certain temperature for a certain period of time. After cooling to room temperature, a metal-containing polyamic acid solution is obtained;

[0008] Step 3: Prepare the obtained metal-containing polyamic acid solution into a casting solution, and form a film of the casting solution at room temperature. After drying, a metal-containing polyamic acid polymer film is obtained;

[0009] Step 4: Carbonize the obtained metal-containing polyamic acid polymer film in an inert atmosphere. Heat from room temperature to a final temperature at a certain heating rate and keep it at a constant temperature for a certain period of time to obtain a metal hybrid gas separation carbon membrane.

[0010] Among them, the metal salt or the metal-organic complex is one or more of Ni(C8H4O4)2, FeCl3, PtCl2(PPh3)2, Pd(acac)2, AgNO3, Zn(CH3COO)2; the diamine monomer having a coordination group is selected from one or more of N,N'-bis(3-aminopropyl)ethylenediamine, 2,6-diaminopyridine, 2,5-diaminoterephthalic acid, 3,3'-dihydroxybenzidine, 2,6-diaminobenzimidazole, 1,5-diaminotetrazole, 1,10-phenanthroline-4,7-diamine; the dianhydride monomer is selected from one or more of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxybisphthalic anhydride, hexafluorodiacid anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

[0011] In the above technical solution, in Step 1, the polar organic solvent is one or a combination of N,N-dimethylformamide, dimethyl sulfoxide, and N,N-dimethylacetamide.

[0012] In the above technical solution, in Step 1, disperse the metal salt or the metal-organic complex in the polar organic solvent, and after ultrasonic stirring at room temperature for 1 to 3 h, an organic solvent dispersion of the metal salt or the metal-organic complex is obtained. Among them, the ratio of the metal salt or the metal-organic complex to the polar organic solvent is 0.01 to 0.1 mol / L.

[0013] In the above technical solution, in Step 1, add the diamine monomer to the dispersion under ultrasonic conditions. The molar ratio of the diamine monomer to the metal salt or the metal-organic complex is 10:1 to 2:1. Bubble N2 for 10 min and stir and react at 30 to 50 °C for 12 to 24 h to obtain a metal-diamine complex solution.

[0014] In the above technical solution, in step 2, a dianhydride monomer is added to the obtained metal-diamine complex solution. The ratio of the dianhydride monomer to the diamine monomer is 1:1. Stir and react at 0-50°C for 4-24 h to obtain a metal-containing polyamic acid solution.

[0015] In the above technical solution, in step 3, the metal-containing polyamic acid solution is defoamed and allowed to stand to obtain a casting solution. The casting solution is cast into a film on a flat plate at room temperature, and then placed in a drying condition at 35-60°C for 6-24 h for solvent evaporation to form a film. Then, it is dried at 100°C-200°C for 12-24 h to obtain a metal-containing polyamic acid polymer film.

[0016] In the above technical solution, in step 4, the metal-containing polyamic acid polymer film is placed in an inert atmosphere and heated from room temperature to 250-700°C at a heating rate of 1-10°C / min, and kept at a constant temperature for 1-24 h to obtain a metal hybrid gas separation carbon membrane.

[0017] In the above technical solution, the inert gas is one of nitrogen and argon, and the flow rate of the inert gas is 150-300 ml / min.

[0018] The beneficial effects of the present invention are as follows: In the method of the present invention, a metal that has a certain promoting effect on gas transport is synthesized into a metal-polymer precursor by in-situ synthesis, which improves the interfacial compatibility between the metal and the polymer and effectively enhances the dispersion degree of metal atoms in the precursor; during the carbonization process, the uniformly dispersed metal atoms avoid the generation of non-selective defects and enhance the gas separation performance of the carbon membrane. It is of great significance for realizing the industrial application of carbon membranes. Description of the Drawings

[0019] Figure 1 Figure 1 is a cross-sectional SEM image and C, O, Ni element distribution maps of the carbon membrane prepared in Example 1 using N,N'-bis(3-aminopropyl)ethylenediamine, hexafluorodiacid anhydride, and Ni(C8H4O4)2. The carbon membrane has a dense structure and the Ni element is uniformly distributed therein;

[0020] Figure 2 Figure 2 is a cross-sectional SEM image and C, O, Fe element distribution maps of the carbon membrane prepared in Example 2 using 2,5-diaminoterephthalic acid, hexafluorodiacid anhydride, and FeCl3. The carbon membrane has a dense structure and the Fe element is uniformly distributed therein; Detailed Embodiments

[0021] The following non-limiting embodiments can enable those of ordinary skill in the art to more comprehensively understand the present invention, but do not limit the present invention in any way.

[0022] In the following embodiments, the test methods are conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial sources unless otherwise specified.

[0023] One of the specific embodiments:

[0024] A preparation method of a metal hybrid gas separation carbon membrane material, specifically, an in-situ preparation method of a metal hybrid gas separation carbon membrane material with a facilitated transport effect, comprising the following steps:

[0025] Step 1: In a polar organic solvent, add a metal salt or a metal organic complex and disperse it fully by ultrasonic treatment. Subsequently, add a diamine monomer with a coordinating group to the dispersion liquid and react for a certain time at a certain temperature. A metal-diamine complex solution is formed through a coordination bond between the metal atom and the coordinating group in the diamine structure;

[0026] Step 2: React the metal-diamine complex solution with a dianhydride monomer for a certain time at a certain temperature, and cool it to room temperature to obtain a metal-containing polyamic acid solution.

[0027] Step 3: Degas and let stand the obtained metal-containing polyamic acid solution to obtain a casting solution. Cast the casting solution on a flat plate at room temperature to form a film, and dry it to obtain a metal-containing polyamic acid polymer film.

[0028] Step 4: Heat the obtained metal-containing polyamic acid polymer film in an inert atmosphere from room temperature to a final temperature at a certain heating rate and keep it at a constant temperature for a certain period of time to obtain a metal hybrid gas separation carbon membrane.

[0029] Furthermore, the polar solvent is one or a combination of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and N,N-dimethylacetamide (DMAC).

[0030] Furthermore, the metal salt or metal organic complex is one or more of Ni(C8H4O4)2, FeCl3, PtCl2(PPh3)2, Pd(acac)2, AgNO3, and Zn(CH3COO)2.

[0031] Furthermore, the ratio of the metal salt to the polar organic solvent is 0.01 mol / L to 0.1 mol / L.

[0032] Furthermore, the diamine monomer is selected from one or more of N,N'-bis(3-aminopropyl)ethylenediamine, 2,6-diaminopyridine, 2,5-diaminoterephthalic acid, 3,3'-dihydroxybenzidine, 2,6-diaminobenzimidazole, 1,5-diaminotetrazole, and 1,10-phenanthroline-4,7-diamine.

[0033] Further, the dianhydride monomer is selected from pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxybisphthalic anhydride, hexafluorodiacid anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

[0034] Further, the molar ratio of the diamine monomer to the metal salt is 10:1 to 2:1.

[0035] Further, the ratio of the dianhydride monomer to the diamine monomer is 1:1.

[0036] Further, in step 1, the metal salt is dispersed in a polar organic solvent, and after ultrasonic stirring at room temperature for 1 - 3 h, a dispersion of the metal salt in the organic solvent is obtained; under ultrasonic conditions, the diamine monomer is added to the dispersion, N2 is bubbled in for 10 min, and the mixture is stirred at 30 - 50 °C for 12 - 24 h to ensure complete reaction, obtaining a metal-diamine complex solution. The purpose of bubbling N2 is to remove the remaining oxygen in the solution.

[0037] Further, in step 2, the dianhydride monomer is added to the obtained metal-diamine complex solution, and the mixture is stirred and reacted at 0 - 50 °C for 4 - 24 h to obtain a metal-containing polyamic acid solution.

[0038] Further, in step 3, the drying conditions are to evaporate the solvent for 6 - 24 h to form a film under drying conditions of 35 - 60 °C, and then place it in a constant-temperature vacuum drying oven and dry it at 100 °C - 200 °C for 12 - 24 h.

[0039] Further, in step 4, the polymer film is cut into film pieces with a size of 1 - 2 cm 2 and, in an inert atmosphere, the temperature is raised from room temperature to 250 - 700 °C at a heating rate of 1 - 10 °C / min and kept at a constant temperature for 1 - 24 h.

[0040] Example 1

[0041] In this example, Ni(C8H4O4)2 is used as the metal source, which is ultrasonically dispersed in DMAc for 2 h, and the addition amount of Ni(C8H4O4)2 is 0.01 mol / L. Subsequently, N,N'-bis(3-aminopropyl)ethylenediamine is added thereto, N2 is bubbled in for 10 min, and the mixture is stirred at 30 °C for 12 h. Then, hexafluorodiacid anhydride is added thereto, where the molar ratio of N,N'-bis(3-aminopropyl)ethylenediamine to Ni(C8H4O4)2 is 10:1, and the molar ratio of the diamine to the dianhydride is 1:1. The solution is stirred and reacted at 0 °C for 24 h. After the solution is warmed to room temperature, the solution is cast into a film on a flat plate, and the solvent is evaporated at 40 °C for 12 h to form a film, and the remaining solvent is removed by heating at 100 °C in a vacuum oven for 12 h. The obtained film is cut into 1 cm 2The square was placed in a carbonization furnace and heated from room temperature to 300 °C at a rate of 3 °C / min under an N2 atmosphere of 300 ml / min, held at a constant temperature of 300 °C for 1 h, then heated to 700 °C at a rate of 3 °C / min and held at a constant temperature of 700 °C for 1 h, and cooled in the furnace to obtain a carbon film.

[0042] Comparative Example 1

[0043] According to the experimental method of Example 1, the difference from Example 1 is that no metal salt / metal organic ligand was added, and a carbon film was prepared. The hydrogen separation performance of this film is shown in Table 1.

[0044] Comparative Example 2

[0045] According to the experimental method of Example 1, the difference from Example 1 is that nano-Ni (particle size of 50 nm) was used as the Ni source to prepare a carbon film. The hydrogen separation performance of this film is shown in Table 1.

[0046] Table 1

[0047]

[0048] Examples 2 - 10

[0049] According to the experimental method of Example 1, the differences from Example 1 are the metal source, diamine, and the ratio of diamine to metal source used in the in-situ synthesis of the polyamic acid solution. The metal source types are FeCl3, PtCl2(PPh3)2, Ag(NO3)2; the ratios are 10:1, 5:1, 2:1, 1:2, and the diamines used are 2,5-diaminoterephthalic acid, 3,3'-dihydroxybenzidine, 2,6-diaminobenzimidazole, 1,10-phenanthroline-4,7-diamine, and the coordination groups are carboxyl, phenolic hydroxyl, imidazole N, and pyridine N respectively. The gas separation performance of the prepared carbon films is shown in Table 2:

[0050] Table 2

[0051]

[0052]

[0053] Example 11

[0054] In this example, Zn(CH3COO)2 was used as the metal source, which was ultrasonically dispersed in DMAc for 2 h. The addition amount of Zn(CH3COO)2 was 0.01 mol / L. Subsequently, 1,10-phenanthroline-4,7-diamine was added thereto, and N2 was bubbled through for 10 min, followed by stirring at 30 °C for 12 h. Then, pyromellitic dianhydride was added thereto. Among them, the molar ratio of 1,10-phenanthroline-4,7-diamine to Zn(CH3COO)2 was 10:1, and the molar ratio of diamine to dianhydride was 1:1. The solution was stirred and reacted at 0 °C for 24 h. After the solution was raised to room temperature, the solution was cast into a film on a flat plate, and the solvent was evaporated at 40 °C for 12 h to form a film. The solvent was removed by heating at 100 °C for 12 h in a vacuum oven. The obtained film was cut into 1 cm2 squares and then placed in a carbonization furnace. Under a N2 atmosphere of 300 ml / min, the temperature was raised from room temperature to 300 °C at a rate of 3 °C / min, held at a constant temperature for 1 h, and then raised to 700 °C at a rate of 3 °C / min and held at a constant temperature for 1 h. After cooling with the furnace, a carbon film was obtained.

[0055] Examples 12 - 14

[0056] According to the experimental method of Example 11, the difference from Example 11 was that the metal sources were Ni(C8H4O4)2, Pd(acac)2, and no metal source respectively to prepare a carbon film, and the gas separation performance of the film was shown in Table 3

[0057] Example 15

[0058] According to the experimental method of Example 11, the difference from Example 11 was that hexafluorodiacid anhydride was used as the dianhydride monomer to prepare a carbon film, and the gas separation performance of the film was shown in Table 3

[0059] Table 3

[0060]

[0061]

[0062] Examples 16 - 18

[0063] According to the experimental method of Example 1, the difference from Example 1 was that the metal sources were changed to Ni(C8H4O4)2, Pd(acac)2, PtCl2(PPh3)2 respectively, and the ratio of diamine to metal source was changed to 5:1. The hydrogen separation performance of the film was shown in Table 4

[0064] Table 4

[0065]

Claims

1. A preparation method of a metal hybrid gas separation carbon membrane material, characterized in that It includes the following steps: Step 1: Disperse a metal salt or a metal organic complex in a polar organic solvent, and then add a diamine monomer with a coordinating group to the dispersion. React at a certain temperature for a certain period of time to form a metal-diamine complex solution; Step 2: React the metal-diamine complex solution with a dianhydride monomer at a certain temperature for a certain period of time. After cooling to room temperature, a metal-containing polyamic acid solution is obtained; Step 3: Prepare the obtained metal-containing polyamic acid solution into a casting solution, and form a film of the casting solution at room temperature. After drying, a metal-containing polyamic acid polymer film is obtained; Step 4: Carbonize the obtained metal-containing polyamic acid polymer film in an inert atmosphere. Heat from room temperature to a final temperature at a certain heating rate and hold for a certain period of time to obtain a metal hybrid gas separation carbon membrane, wherein, the metal salt or the metal organic complex is one or more of Ni(C8H4O4)2, FeCl3, PtCl2(PPh3)2, Pd(acac)2, AgNO3, Zn(CH3COO)2; the diamine monomer with a coordinating group is selected from one or more of N,N'-bis(3-aminopropyl)ethylenediamine, 2,6-diaminopyridine, 2,5-diaminoterephthalic acid, 3,3'-dihydroxybenzidine, 2,6-diaminobenzimidazole, 1,5-diaminotetrazole, 1,10-phenanthroline-4,7-diamine; the dianhydride monomer is selected from one or more of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, hexafluorodiacid anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride.

2. The method according to claim 1, wherein In the step 1, the polar organic solvent is one or a combination of N,N-dimethylformamide, dimethyl sulfoxide, and N,N-dimethylacetamide.

3. The method according to claim 1, wherein In the step 1, disperse the metal salt or the metal organic complex in the polar organic solvent, and obtain an organic solvent dispersion of the metal salt or the metal organic complex after ultrasonic stirring at room temperature for 1 to 3 h. Among them, the ratio of the metal salt or the metal organic complex to the polar organic solvent is 0.01 to 0.1 mol / L.

4. The method according to claim 1, characterized in that, In the step 1, add the diamine monomer to the dispersion under ultrasonic conditions. The molar ratio of the diamine monomer to the metal salt or the metal organic complex is 10:1 to 2:

1. Bubble with N2 for 10 min, and stir and react at 30 to 50 °C for 12 to 24 h to obtain a metal-diamine complex solution.

5. The method according to claim 1, characterized in that, In the step 2, add the dianhydride monomer to the obtained metal-diamine complex solution. The ratio of the dianhydride monomer to the diamine monomer is 1:

1. Stir and react at 0 to 50 °C for 4 to 24 h to obtain a metal-containing polyamic acid solution.

6. The method according to claim 1, wherein In the step 3, defoam and stand the metal-containing polyamic acid solution to obtain a casting solution. Cast the casting solution into a film on a flat plate at room temperature, and then place it under drying conditions at 35 to 60 °C to evaporate the solvent for 6 to 24 h to form a film. Then dry it at 100 °C to 200 °C for 12 to 24 h to obtain a metal-containing polyamic acid polymer film.

7. The method according to claim 1, characterized in that, In the step 4, the polyamic acid polymer film containing metal is placed in an inert atmosphere and heated from room temperature to 250-700 °C at a heating rate of 1-10 °C / min, and kept at a constant temperature for 1-24 h to obtain a metal hybrid gas separation carbon membrane.

8. The method according to claim 1, characterized in that, The inert gas is one of nitrogen and argon, and the flow rate of the inert gas is 150-300 ml / min.

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