Preparation method of copc-mo composite hollow fiber membrane

Abstract

The present application relates to the technical field of gas separation, in particular to a preparation method of CoPc-Mo composite hollow fiber membrane. The preparation method comprises the following steps: preparing a hollow fiber ceramic membrane; preparing a PDMS-Mo hollow fiber membrane; preparing CoPc-TFPN-COF and post-modifying carboxyl; and preparing a CoPc-Mo composite hollow fiber membrane. The present application prepares CoPc-TFPN-COF and modifies CoPc-TFPN-COF to obtain CoPc-TFPN-COOH. Compared with CoPc-TFPN-COF, the pore size of CoPc-TFPN-COOH is not much different, but CoPc-TFPN-COOH has a higher specific surface area, which makes CoPc-TFPN-COOH have the temperature resistance of CoPc-TFPN-COF while the maximum flux of helium reaches 288 GPU, so it performs more excellent in gas adsorption.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation, and in particular to a method for preparing a CoPc-Mo composite hollow fiber membrane. Background Art

[0002] Helium, due to its unique properties such as low boiling point, low density, low solubility, high thermal conductivity, and high ionization energy, plays an irreplaceable role in fields such as MRI scanners, aerospace, industrial leak detection systems, electronics and fiber optic manufacturing, welding, and nuclear research facilities. As a scarce, non-renewable resource, the only readily available source of helium is natural gas. Common methods for extracting helium from natural gas include cryogenic distillation, pressure swing adsorption, and membrane separation. Compared to cryogenic distillation and pressure swing adsorption, membrane separation involves no phase change and therefore consumes less energy. Furthermore, membrane separation technology offers advantages such as a small footprint, simple operation and maintenance, and a pollution-free environment, presenting broad application prospects in the field of helium extraction from natural gas.

[0003] Compared to traditional gas separation methods, membrane separation offers advantages such as low cost, ease of operation, and significant separation effects. Patent CN202311302077.X mentions a hollow core-shell metal-organic framework / polyimide mixed matrix membrane, prepared using 6FDA-MDA polyimide, for the separation of H2 and CH4. At a temperature of 25°C and a feed-side pressure of 0.2 MPa, the polyimide mixed matrix membrane achieves an H2 permeability of 60-105 barrer, a CH4 permeability of 0.5-0.7 barrer, and an H2 / CH4 selectivity of 100-150. However, these gas separation membranes exhibit a trade-off effect: high flux results in low selectivity, while high selectivity results in low flux. Moreover, none of them have been expanded to be applied to membrane helium extraction. The mullite whisker hollow fiber membrane involved has only been used in the field of oil-water separation, and its function in helium separation has not been deeply studied and explored. Therefore, the present invention provides a preparation method of CoPc-Mo composite hollow fiber membrane to solve the above problems. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a method for preparing a CoPc-Mo composite hollow fiber membrane.

[0005] A method for preparing a CoPc-Mo composite hollow fiber membrane comprises the following steps:

[0006] S1: Preparation of hollow fiber ceramic membrane

[0007] Weigh polyethersulfone, polyvinylpyrrolidone and N-methylpyrrolidone in sequence and add them into a three-necked flask, then add fly ash and Al2O3 to prepare a membrane casting solution, pour the membrane casting solution into a feed liquid tank, extrude the original membrane through a spinneret under nitrogen pressure, treat the original membrane to obtain membrane filaments, then place the membrane filaments into a crucible, add AlF3 and Al2O3, and then sinter in a muffle furnace to obtain a hollow fiber ceramic membrane;

[0008] S2: Preparation of PDMS-Mo hollow fiber membrane

[0009] The two ends of the hollow fiber ceramic base membrane are then sealed with sealant and hydroxylated to obtain a HO-Mo membrane. Polydimethylsiloxane is dissolved in n-hexane, and ethyl orthosilicate and dibutyltin dilaurate are added. The mixture is allowed to stand for 3-6 hours to pre-crosslink and form a precursor solution. The precursor solution is then dip-coated onto the HO-Mo membrane to obtain a PDMS-Mo hollow fiber membrane.

[0010] S3: Preparation of CoPc-TFPN-COF and post-carboxyl modification

[0011] Cobalt octahydroxyphthalocyanine and tetrafluoroterephthalonitrile were placed in an ampoule, and N,N-dimethylacetamide, mesitylene, and triethylamine were added to prepare CoPc-TFPN-COF powder. The CoPc-TFPN-COF powder and NaOH solution were added to a single-necked round-bottom flask equipped with a condenser to prepare CoPc-TFPN-COOH.

[0012] S4: Preparation of CoPc-Mo composite hollow fiber membrane

[0013] The method comprises the following steps: dissolving trimesoyl chloride in n-hexane to prepare an organic phase solution, dissolving cystamine dihydrochloride and NaOH in deionized water to prepare an aqueous phase solution, soaking a PDMS-Mo hollow fiber membrane in the organic phase solution to obtain a single-treatment PDMS-Mo hollow fiber membrane, adding CoPc-TFPN-COOH to the aqueous phase solution to obtain a mixed aqueous phase solution, and then soaking the single-treatment PDMS-Mo hollow fiber membrane in the mixed aqueous phase solution to obtain a CoPc-Mo composite hollow fiber membrane.

[0014] Furthermore, step S1 of preparing a hollow fiber ceramic membrane comprises the following steps:

[0015] S1.1: Weigh polyethersulfone, polyvinylpyrrolidone, and N-methylpyrrolidone into a three-necked flask, add them in sequence, mechanically stir at room temperature for 1-5 hours, then heat to 60-80°C and stir until completely dissolved. Then, add fly ash and Al2O3 and stir in an oil bath at 60-80°C for 6-8 hours to form a casting solution.

[0016] S1.2: Degas under vacuum at room temperature, pour the casting solution into a feed tank, extrude the original membrane through a spinneret under a nitrogen pressure of 0.1-0.5 MPa, soak the original membrane in distilled water, and replace the distilled water every 6-8 hours. After 12-24 hours, vacuum dry at 60-80°C for 6-8 hours, and cut into 5-8 cm small segments to obtain membrane filaments;

[0017] S1.3: The membrane filament is placed in a crucible, and AlF3 and Al2O3 are added, and then placed in a muffle furnace for sintering by a step-by-step sintering method. In the first stage, the temperature reaches 800-1000°C after 180-240 minutes. This process promotes the decomposition of organic matter in the ceramic embryo. The temperature is kept warm for 60-80 minutes to ensure the full decomposition of the fly ash components. In the second stage, the temperature is continued to rise to 1200-1400°C and kept warm for 80-120 minutes. After the insulation is completed, it is cooled to room temperature to obtain a hollow fiber ceramic membrane.

[0018] Furthermore, step S2 of preparing a multilayer composite film comprises the following steps:

[0019] S2.1: Seal both ends of the hollow fiber ceramic membrane with a sealant, perform a hydroxylation treatment, and soak the membrane in a mixed solution of acetone:ethanol:water (volume ratio 1:1:(1-4)) for 10-30 minutes to obtain a HO-Mo membrane.

[0020] S2.2: Dissolve polydimethylsiloxane in n-hexane, heat to 60-80°C and stir for 1-2 hours, then add ethyl orthosilicate and dibutyltin dilaurate, stir for 8-12 hours, and let it stand for 3-6 hours to pre-crosslink to form a precursor solution. Dip-coat the precursor solution onto the HO-Mo membrane for 1-2 hours, then place it in a vacuum oven at 40-60°C and dry it for 4-6 hours before taking it out to obtain the PDMS-Mo hollow fiber membrane.

[0021] Furthermore, step S3 of processing the multilayer composite film comprises the following steps:

[0022] S3.1: Place octahydroxyphthalocyanine cobalt and tetrafluoroterephthalonitrile in an ampoule, then add N,N-dimethylacetamide and mesitylene, ultrasonicate for 10-20 minutes, add triethylamine, continue ultrasonicate for 5-10 minutes, seal the glass bottle with a flame spray gun under negative pressure and liquid nitrogen freezing conditions, then place the glass bottle in an oven set at 130-150°C, heat for 60-72 hours, remove, and let it cool naturally, wash three times with N,N-dimethylacetamide, N,N-dimethylformamide, pure water, dichloromethane, and tetrahydrofuran respectively, until the filtrate is colorless, and then use tetrahydrofuran and acetone as extractants for Soxhlet extraction, each for 12-24 hours, and then dry in a vacuum at 80-120°C to obtain CoPc-TFPN-COF powder;

[0023] S3.2: CoPc-TFPN-COF powder and a 20-30% NaOH solution are added to a single-necked round-bottom flask equipped with a condenser. The mass ratio of CoPc-TFPN-COF and NaOH solution is 1:(220-300). The mixture is heated to 100-120°C for 3-5 days. After cooling to room temperature, a solid product is obtained. The solid product is filtered and refluxed in water for 2-6 hours, and then refluxed in 1-3 mol / L HCl for 2-6 hours. The precipitate is collected by centrifugation and rinsed with acetone, then washed with water and tetrahydrofuran, and finally Soxhlet extraction is performed with tetrahydrofuran as a solvent for 12-24 hours. The solid is collected and dried to obtain CoPc-TFPN-COOH.

[0024] Furthermore, step S4 of preparing phosphate soft glass liquid includes the following steps:

[0025] S4.1: Dissolve trimesoyl chloride in n-hexane to prepare an organic phase solution, then dissolve cystamine dihydrochloride and NaOH in deionized water to prepare an aqueous phase solution. Soak a PDMS-Mo hollow fiber membrane in 20-50 parts by volume of the organic phase solution for 10-60 seconds to obtain a primary treated PDMS-Mo hollow fiber membrane.

[0026] S4.2: Adding CoPc-TFPN-COOH to the aqueous solution, controlling the mass fraction of CoPc-TFPN-COOH to be 0.1-0.8%, to obtain a mixed aqueous solution;

[0027] S4.3: Then, the treated PDMS-Mo hollow fiber membrane is immersed in the mixed aqueous phase solution for 3-6 minutes, rinsed with deionized water for 3-6 times, and finally dried under vacuum conditions at 60-80°C to obtain a CoPc-Mo composite hollow fiber membrane.

[0028] Furthermore, in step S1.1, the mass ratio of polyethersulfone, polyvinylpyrrolidone, N-methylpyrrolidone, fly ash and Al2O3 is 9:1:(40-60):60:20.

[0029] Furthermore, in step S1.3, the mass ratio of the membrane filament, AlF3 and Al2O3 is (1-3):1:1.

[0030] Furthermore, in step S2.2, the mass ratio of polydimethylsiloxane, n-hexane, ethyl orthosilicate and dibutyltin dilaurate is 1:(4-8):1:2.

[0031] Furthermore, in step S3.1, the mass ratio of octahydroxyphthalocyanine cobalt, tetrafluoroterephthalonitrile, N,N-dimethylacetamide, mesitylene and triethylamine is (1-3): 1:50:50:5.

[0032] Furthermore, in step S4.1, the mass ratio of trimesoyl chloride to n-hexane is (1-5):100, and the mass ratio of cystamine dihydrochloride, NaOH and water is (2-5):1:(200-250).

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] 1. The present invention prepares CoPc-TFPN-COF and carboxylates CoPc-TFPN-COF to obtain CoPc-TFPN-COOH. Compared with CoPc-TFPN-COF, the pore size of the carboxyl-modified CoPc-TFPN-COOH is not much different, but CoPc-TFPN-COOH has a higher specific surface area. This allows CoPc-TFPN-COOH to have the temperature resistance of CoPc-TFPN-COF while achieving a maximum helium flux of 288 GPU, indicating that it performs better in gas adsorption.

[0035] 2. The present invention utilizes the composite use of two materials with different flux and selectivity to prepare a composite hollow fiber membrane with high porosity. It has good heat resistance when used as a gas separation membrane and has high selectivity for CH4, CO2, and He. It can be well applied to the separation of helium in natural gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable one skilled in the relevant art to make and use the present disclosure.

[0037] Figure 1 This is a flow chart of a method for preparing a CoPc-Mo composite hollow fiber membrane used in an embodiment of the present invention.

[0038] Figure 2 Graph showing the Fourier transform infrared data of CoPc-TFPN-COF and CoPc-TFPN-COOH of the present invention.

[0039] Figure 3 Graph showing the specific surface area and pore size data of CoPc-TFPN-COF and carboxyl-post-modified CoPc-TFPN-COOH of the present invention.

[0040] Figure 4 This is a graph showing the thermal decomposition performance data of the CoPc-Mo composite hollow fiber membrane prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0041] The following describes in detail a method for preparing a CoPc-Mo composite hollow fiber membrane provided by the present invention, with reference to the accompanying drawings and specific examples. It is also noted that, for the sake of completeness, the following examples are best and preferred embodiments, and those skilled in the art may employ alternative methods for implementing known techniques. Furthermore, the accompanying drawings are intended only to provide a more detailed description of the embodiments and are not intended to limit the present invention.

[0042] Example 1:

[0043] A method for preparing a CoPc-Mo composite hollow fiber membrane, such as Figure 1 As shown, the following steps are included:

[0044] S1: Preparation of hollow fiber ceramic membrane

[0045] S1.1: Weigh 18g of polyethersulfone, 2g of polyvinylpyrrolidone, and 90g of N-methylpyrrolidone into a three-necked flask, add them in sequence, mechanically stir at room temperature for 2h, then heat to 80°C and stir until completely dissolved. Then, add 120g of fly ash and 40g of Al2O3 and stir in an 80°C oil bath for 8h to form a casting solution.

[0046] S1.2: Degas under vacuum at room temperature, pour the casting solution into a feed tank, extrude the original membrane through a spinneret under a nitrogen pressure of 0.2 MPa, soak the original membrane in distilled water, and replace the distilled water every 8 hours. After 24 hours, vacuum dry at 80°C for 8 hours and cut into 7 cm small segments to obtain membrane filaments;

[0047] S1.3: Put 20g of membrane filament into the crucible, add 10g of AlF3 and 10g of Al2O3, and then put it into the muffle furnace and sinter it by the step sintering method. In the first stage, it reaches 900℃ after 190min. This process promotes the decomposition of organic matter in the ceramic embryo. Keep it warm for 80min to ensure the full decomposition of the fly ash components; in the second stage, continue to heat up to 1200℃ and keep it warm for 90min. After the insulation is completed, cool it to room temperature to obtain a hollow fiber ceramic membrane.

[0048] S2: Preparation of PDMS-Mo hollow fiber membrane

[0049] S2.1: Seal both ends of the hollow fiber ceramic membrane with sealant, perform hydroxylation, and soak the membrane in a mixed solution of acetone:ethanol:water (volume ratio: 1:1:3) for 30 minutes to obtain a HO-Mo membrane.

[0050] S2.2: Dissolve 3 g of polydimethylsiloxane in 18 g of n-hexane, heat to 80°C and stir for 2 h, then add 3 g of ethyl orthosilicate and 6 g of dibutyltin dilaurate, stir for 9 h, and let it stand for 6 h to pre-crosslink to form a precursor solution. Dip-coat the precursor solution onto the HO-Mo membrane for 2 h, then place it in a vacuum oven at 60°C and dry for 6 h before taking out to obtain the PDMS-Mo hollow fiber membrane.

[0051] S3: Preparation of CoPc-TFPN-COF and post-carboxyl modification

[0052] S3.1: 0.175 g of octahydroxyphthalocyanine cobalt and 0.1 g of tetrafluoroterephthalonitrile were placed in an ampoule, and 5 g of N, N-dimethylacetamide and 5 g of mesitylene were added. After ultrasonication for 10-20 min, 0.5 g of triethylamine was added and ultrasonication was continued for 10 min. The glass bottle was sealed with a flame spray gun under negative pressure and liquid nitrogen freezing conditions. The glass bottle was placed in an oven set at 150°C and heated for 72 h. The product was taken out and allowed to cool naturally. The product was washed three times with N, N-dimethylacetamide, N, N-dimethylformamide, pure water, dichloromethane and tetrahydrofuran respectively until the filtrate was colorless. The product was then subjected to Soxhlet extraction using tetrahydrofuran and acetone as extractants. After 24 h of extraction each, the product was dried in vacuo at 120°C to obtain CoPc-TFPN-COF powder.

[0053] S3.2: Add 100 mg of CoPc-TFPN-COF powder and 25 g of 20% NaOH solution to a single-necked round-bottom flask equipped with a condenser, heat the mixture to 120°C for 5 days, cool to room temperature, and obtain a solid product. The solid product is filtered and refluxed in water for 6 hours, then refluxed in 1 mol / L HCl for 6 hours, the precipitate is collected by centrifugation and rinsed with acetone, then washed with water and tetrahydrofuran, and finally Soxhlet extraction is performed with tetrahydrofuran as a solvent for 24 hours. The solid is collected and dried to obtain CoPc-TFPN-COOH.

[0054] Schematic diagram of CoPc-TFPN-COF, CoPc-TFPN-COOH, and reaction diagram of carboxyl post-modification.

[0055]

[0056] S4: Preparation of CoPc-Mo composite hollow fiber membrane

[0057] S4.1: Dissolve 1 g of trimesoyl chloride in 50 g of n-hexane to prepare an organic phase solution. Then, dissolve 1 g of cystamine dihydrochloride and 0.5 g of NaOH in 50 g of deionized water to prepare an aqueous phase solution. Soak 50 mL of the organic phase solution in a PDMS-Mo hollow fiber membrane for 60 s to obtain a single-treated PDMS-Mo hollow fiber membrane.

[0058] S4.2: Adding CoPc-TFPN-COOH to the aqueous solution, controlling the mass fraction of CoPc-TFPN-COOH to be 0.1%, to obtain a mixed aqueous solution;

[0059] S4.3: Then, the treated PDMS-Mo hollow fiber membrane was immersed in the mixed aqueous phase solution for 6 minutes, rinsed with deionized water 6 times, and finally dried under vacuum conditions at 80°C to obtain a CoPc-Mo composite hollow fiber membrane.

[0060] Example 2:

[0061] A method for preparing a CoPc-Mo composite hollow fiber membrane, such as Figure 1 As shown, the following steps are included:

[0062] S1: Preparation of hollow fiber ceramic membrane

[0063] S1.1: Weigh 18g of polyethersulfone, 2g of polyvinylpyrrolidone, and 90g of N-methylpyrrolidone into a three-necked flask, add them in sequence, mechanically stir at room temperature for 2h, then heat to 80°C and stir until completely dissolved. Then, add 120g of fly ash and 40g of Al2O3 and stir in an 80°C oil bath for 8h to form a casting solution.

[0064] S1.2: Degas under vacuum at room temperature, pour the casting solution into a feed tank, extrude the original membrane through a spinneret under a nitrogen pressure of 0.2 MPa, soak the original membrane in distilled water, and replace the distilled water every 8 hours. After 24 hours, vacuum dry at 80°C for 8 hours and cut into 7 cm small segments to obtain membrane filaments;

[0065] S1.3: Put 20g of membrane filament into the crucible, add 10g of AlF3 and 10g of Al2O3, and then put it into the muffle furnace and sinter it by the step sintering method. In the first stage, it reaches 900℃ after 190min. This process promotes the decomposition of organic matter in the ceramic embryo. Keep it warm for 80min to ensure the full decomposition of the fly ash components; in the second stage, continue to heat up to 1200℃ and keep it warm for 90min. After the insulation is completed, cool it to room temperature to obtain a hollow fiber ceramic membrane.

[0066] S2: Preparation of PDMS-Mo hollow fiber membrane

[0067] S2.1: Seal both ends of the hollow fiber ceramic membrane with sealant, perform hydroxylation, and soak the membrane in a mixed solution of acetone:ethanol:water (volume ratio: 1:1:3) for 30 minutes to obtain a HO-Mo membrane.

[0068] S2.2: Dissolve 3 g of polydimethylsiloxane in 18 g of n-hexane, heat to 80°C and stir for 2 h, then add 3 g of ethyl orthosilicate and 6 g of dibutyltin dilaurate, stir for 9 h, and let it stand for 6 h to pre-crosslink to form a precursor solution. Dip-coat the precursor solution onto the HO-Mo membrane for 2 h, then place it in a vacuum oven at 60°C and dry for 6 h before taking out to obtain the PDMS-Mo hollow fiber membrane.

[0069] S3: Preparation of CoPc-TFPN-COF and post-carboxyl modification

[0070] S3.1: 0.175 g of octahydroxyphthalocyanine cobalt and 0.1 g of tetrafluoroterephthalonitrile were placed in an ampoule, and 5 g of N, N-dimethylacetamide and 5 g of mesitylene were added. After ultrasonication for 10-20 min, 0.5 g of triethylamine was added and ultrasonication was continued for 10 min. The glass bottle was sealed with a flame spray gun under negative pressure and liquid nitrogen freezing conditions. The glass bottle was placed in an oven set at 150°C and heated for 72 h. The product was taken out and allowed to cool naturally. The product was washed three times with N, N-dimethylacetamide, N, N-dimethylformamide, pure water, dichloromethane and tetrahydrofuran respectively until the filtrate was colorless. The product was then subjected to Soxhlet extraction using tetrahydrofuran and acetone as extractants. After 24 h of extraction each, the product was dried in vacuo at 120°C to obtain CoPc-TFPN-COF powder.

[0071] S3.2: Add 100 mg of CoPc-TFPN-COF powder and 25 g of 20% NaOH solution to a single-necked round-bottom flask equipped with a condenser, heat the mixture to 120°C for 5 days, cool to room temperature, and obtain a solid product. The solid product is filtered and refluxed in water for 6 hours, then refluxed in 1 mol / L HCl for 6 hours, the precipitate is collected by centrifugation and rinsed with acetone, then washed with water and tetrahydrofuran, and finally Soxhlet extraction is performed with tetrahydrofuran as a solvent for 24 hours. The solid is collected and dried to obtain CoPc-TFPN-COOH.

[0072] S4: Preparation of CoPc-Mo composite hollow fiber membrane

[0073] S4.1: Dissolve 1 g of trimesoyl chloride in 50 g of n-hexane to prepare an organic phase solution. Then, dissolve 1 g of cystamine dihydrochloride and 0.5 g of NaOH in 50 g of deionized water to prepare an aqueous phase solution. Soak 50 mL of the organic phase solution in a PDMS-Mo hollow fiber membrane for 60 s to obtain a single-treated PDMS-Mo hollow fiber membrane.

[0074] S4.2: Adding CoPc-TFPN-COOH to the aqueous solution, controlling the mass fraction of CoPc-TFPN-COOH to be 0.3%, to obtain a mixed aqueous solution;

[0075] S4.3: Then, the treated PDMS-Mo hollow fiber membrane was immersed in the mixed aqueous phase solution for 6 minutes, rinsed with deionized water 6 times, and finally dried under vacuum conditions at 80°C to obtain a CoPc-Mo composite hollow fiber membrane.

[0076] Example 3:

[0077] A method for preparing a CoPc-Mo composite hollow fiber membrane, such as Figure 1 As shown, the following steps are included:

[0078] S1: Preparation of hollow fiber ceramic membrane

[0079] S1.1: Weigh 18g of polyethersulfone, 2g of polyvinylpyrrolidone, and 90g of N-methylpyrrolidone into a three-necked flask, add them in sequence, mechanically stir at room temperature for 2h, then heat to 80°C and stir until completely dissolved. Then, add 120g of fly ash and 40g of Al2O3 and stir in an 80°C oil bath for 8h to form a casting solution.

[0080] S1.2: Degas under vacuum at room temperature, pour the casting solution into a feed tank, extrude the original membrane through a spinneret under a nitrogen pressure of 0.2 MPa, soak the original membrane in distilled water, and replace the distilled water every 8 hours. After 24 hours, vacuum dry at 80°C for 8 hours and cut into 7 cm small segments to obtain membrane filaments;

[0081] S1.3: Put 20g of membrane filament into the crucible, add 10g of AlF3 and 10g of Al2O3, and then put it into the muffle furnace and sinter it by the step sintering method. In the first stage, it reaches 900℃ after 190min. This process promotes the decomposition of organic matter in the ceramic embryo. Keep it warm for 80min to ensure the full decomposition of the fly ash components; in the second stage, continue to heat up to 1200℃ and keep it warm for 90min. After the insulation is completed, cool it to room temperature to obtain a hollow fiber ceramic membrane.

[0082] S2: Preparation of PDMS-Mo hollow fiber membrane

[0083] S2.1: Seal both ends of the hollow fiber ceramic membrane with sealant, perform hydroxylation, and soak the membrane in a mixed solution of acetone:ethanol:water (volume ratio: 1:1:3) for 30 minutes to obtain a HO-Mo membrane.

[0084] S2.2: Dissolve 3 g of polydimethylsiloxane in 18 g of n-hexane, heat to 80°C and stir for 2 h, then add 3 g of ethyl orthosilicate and 6 g of dibutyltin dilaurate, stir for 9 h, and let it stand for 6 h to pre-crosslink to form a precursor solution. Dip-coat the precursor solution onto the HO-Mo membrane for 2 h, then place it in a vacuum oven at 60°C and dry for 6 h before taking out to obtain the PDMS-Mo hollow fiber membrane.

[0085] S3: Preparation of CoPc-TFPN-COF and post-carboxyl modification

[0086] S3.1: 0.175 g of octahydroxyphthalocyanine cobalt and 0.1 g of tetrafluoroterephthalonitrile were placed in an ampoule, and 5 g of N, N-dimethylacetamide and 5 g of mesitylene were added. After ultrasonication for 10-20 min, 0.5 g of triethylamine was added and ultrasonication was continued for 10 min. The glass bottle was sealed with a flame spray gun under negative pressure and liquid nitrogen freezing conditions. The glass bottle was placed in an oven set at 150°C and heated for 72 h. The product was taken out and allowed to cool naturally. The product was washed three times with N, N-dimethylacetamide, N, N-dimethylformamide, pure water, dichloromethane and tetrahydrofuran respectively until the filtrate was colorless. The product was then subjected to Soxhlet extraction using tetrahydrofuran and acetone as extractants. After 24 h of extraction each, the product was dried in vacuo at 120°C to obtain CoPc-TFPN-COF powder.

[0087] S3.2: Add 100 mg of CoPc-TFPN-COF powder and 25 g of 20% NaOH solution to a single-necked round-bottom flask equipped with a condenser, heat the mixture to 120°C for 5 days, cool to room temperature, and obtain a solid product. The solid product is filtered and refluxed in water for 6 hours, then refluxed in 1 mol / L HCl for 6 hours, the precipitate is collected by centrifugation and rinsed with acetone, then washed with water and tetrahydrofuran, and finally Soxhlet extraction is performed with tetrahydrofuran as a solvent for 24 hours. The solid is collected and dried to obtain CoPc-TFPN-COOH.

[0088] S4: Preparation of CoPc-Mo composite hollow fiber membrane

[0089] S4.1: Dissolve 1 g of trimesoyl chloride in 50 g of n-hexane to prepare an organic phase solution. Then, dissolve 1 g of cystamine dihydrochloride and 0.5 g of NaOH in 50 g of deionized water to prepare an aqueous phase solution. Soak 50 mL of the organic phase solution in a PDMS-Mo hollow fiber membrane for 60 s to obtain a single-treated PDMS-Mo hollow fiber membrane.

[0090] S4.2: Adding CoPc-TFPN-COOH to the aqueous solution, controlling the mass fraction of CoPc-TFPN-COOH to be 0.5%, to obtain a mixed aqueous solution;

[0091] S4.3: Then, the treated PDMS-Mo hollow fiber membrane was immersed in the mixed aqueous phase solution for 6 minutes, rinsed with deionized water 6 times, and finally dried under vacuum conditions at 80°C to obtain a CoPc-Mo composite hollow fiber membrane.

[0092] Example 4:

[0093] S1: Preparation of hollow fiber ceramic membrane

[0094] S1.1: Weigh 18g of polyethersulfone, 2g of polyvinylpyrrolidone, and 90g of N-methylpyrrolidone into a three-necked flask, add them in sequence, mechanically stir at room temperature for 2h, then heat to 80°C and stir until completely dissolved. Then, add 120g of fly ash and 40g of Al2O3 and stir in an 80°C oil bath for 8h to form a casting solution.

[0095] S1.2: Degas under vacuum at room temperature, pour the casting solution into a feed tank, extrude the original membrane through a spinneret under a nitrogen pressure of 0.2 MPa, soak the original membrane in distilled water, and replace the distilled water every 8 hours. After 24 hours, vacuum dry at 80°C for 8 hours and cut into 7 cm small segments to obtain membrane filaments;

[0096] S1.3: Put 20g of membrane filament into the crucible, add 10g of AlF3 and 10g of Al2O3, and then put it into the muffle furnace and sinter it by the step sintering method. In the first stage, it reaches 900℃ after 190min. This process promotes the decomposition of organic matter in the ceramic embryo. Keep it warm for 80min to ensure the full decomposition of the fly ash components; in the second stage, continue to heat up to 1200℃ and keep it warm for 90min. After the insulation is completed, cool it to room temperature to obtain a hollow fiber ceramic membrane.

[0097] S2: Preparation of PDMS-Mo hollow fiber membrane

[0098] S2.1: Seal both ends of the hollow fiber ceramic membrane with sealant, perform hydroxylation, and soak the membrane in a mixed solution of acetone:ethanol:water (volume ratio: 1:1:3) for 30 minutes to obtain a HO-Mo membrane.

[0099] S2.2: Dissolve 3 g of polydimethylsiloxane in 18 g of n-hexane, heat to 80°C and stir for 2 h, then add 3 g of ethyl orthosilicate and 6 g of dibutyltin dilaurate, stir for 9 h, and let it stand for 6 h to pre-crosslink to form a precursor solution. Dip-coat the precursor solution onto the HO-Mo membrane for 2 h, then place it in a vacuum oven at 60°C and dry for 6 h before taking out to obtain the PDMS-Mo hollow fiber membrane.

[0100] S3: Preparation of CoPc-TFPN-COF and post-carboxyl modification

[0101] S3.1: 0.175 g of octahydroxyphthalocyanine cobalt and 0.1 g of tetrafluoroterephthalonitrile were placed in an ampoule, and 5 g of N, N-dimethylacetamide and 5 g of mesitylene were added. After ultrasonication for 10-20 min, 0.5 g of triethylamine was added and ultrasonication was continued for 10 min. The glass bottle was sealed with a flame spray gun under negative pressure and liquid nitrogen freezing conditions. The glass bottle was placed in an oven set at 150°C and heated for 72 h. The product was taken out and allowed to cool naturally. The product was washed three times with N, N-dimethylacetamide, N, N-dimethylformamide, pure water, dichloromethane and tetrahydrofuran respectively until the filtrate was colorless. The product was then subjected to Soxhlet extraction using tetrahydrofuran and acetone as extractants. After 24 h of extraction each, the product was dried in vacuo at 120°C to obtain CoPc-TFPN-COF powder.

[0102] S3.2: Add 100 mg of CoPc-TFPN-COF powder and 25 g of 20% NaOH solution to a single-necked round-bottom flask equipped with a condenser, heat the mixture to 120°C for 5 days, cool to room temperature, and obtain a solid product. The solid product is filtered and refluxed in water for 6 hours, then refluxed in 1 mol / L HCl for 6 hours, the precipitate is collected by centrifugation and rinsed with acetone, then washed with water and tetrahydrofuran, and finally Soxhlet extraction is performed with tetrahydrofuran as a solvent for 24 hours. The solid is collected and dried to obtain CoPc-TFPN-COOH.

[0103] S4: Preparation of CoPc-Mo composite hollow fiber membrane

[0104] S4.1: Dissolve 1 g of trimesoyl chloride in 50 g of n-hexane to prepare an organic phase solution. Then, dissolve 1 g of cystamine dihydrochloride and 0.5 g of NaOH in 50 g of deionized water to prepare an aqueous phase solution. Soak 50 mL of the organic phase solution in a PDMS-Mo hollow fiber membrane for 60 s to obtain a single-treated PDMS-Mo hollow fiber membrane.

[0105] S4.2: Adding CoPc-TFPN-COOH to the aqueous solution, controlling the mass fraction of CoPc-TFPN-COOH to be 0.8%, to obtain a mixed aqueous solution;

[0106] S4.3: Then, the treated PDMS-Mo hollow fiber membrane was immersed in the mixed aqueous phase solution for 6 minutes, rinsed with deionized water 6 times, and finally dried under vacuum conditions at 80°C to obtain a CoPc-Mo composite hollow fiber membrane.

[0107] Comparative Example 1:

[0108] Compared with Example 3, the difference of Comparative Example 1 is that CoPc-TFPN-COOH is not added, and it is a PDMS-Mo composite hollow fiber membrane with 0% CoPc-TFPN-COOH, specifically: "1g of trimesoyl chloride (TMC) is dissolved in 50g of n-hexane to prepare an organic phase, and 1g of cystamine dihydrochloride and 0.5g of NaOH are dissolved in 50g of deionized water to prepare an aqueous phase. Take 50ml of the above organic phase solution to soak PDMS-Mo for about 60s, and then place it in the above aqueous phase solution to which 0% CoPc-TFPN-COOH is added and soak for 6min, and then rinse the composite membrane with deionized water 6 times. Finally, it is dried under vacuum conditions at 80°C to obtain a PDMS-Mo composite hollow fiber membrane with 0% CoPc-TFPN-COOH". The prepared CoPc-Mo composite hollow fiber membrane is recorded as Comparative Example 1.

[0109] Comparative Example 2:

[0110] Compared with Example 1, the difference of Comparative Example 2 is that CoPc-TFPN-COF powder is added to step S4 instead of CoPc-TFPN-COOH, specifically: "1g of trimesoyl chloride (TMC) is dissolved in 50g of n-hexane to prepare an organic phase, and 1g of cystamine dihydrochloride and 0.5g of NaOH are dissolved in 50g of deionized water to prepare an aqueous phase. Take 50ml of the above organic phase solution to soak PDMS-Mo for about 60s, and then place it in the above aqueous phase solution to which 0.5% CoPc-TFPN-COF is added and soak for 6min, and then rinse the composite membrane with deionized water 6 times. Finally, dry it under vacuum conditions at 80°C to obtain a 0.5% CoPc-TFPN-COF PDMS-Mo composite hollow fiber membrane". The prepared CoPc-Mo composite hollow fiber membrane is recorded as Comparative Example 2.

[0111] The CoPc-Mo composite hollow fiber membranes of Examples 1-3 and Comparative Examples 1-3 were placed in an accelerated UV aging device, with a cumulative irradiation of 200 kWh / m 2 , and then refer to GB / T31034-2014 to test the elongation at break of the test specimens before and after aging.

[0112] The gas separation performance tests of the hollow fiber membranes prepared in Examples 1 to 4 and Comparative Examples 1-2 are as follows:

[0113] The hollow fiber membranes prepared in Examples 1 to 4 and Comparative Examples 1-2 were encapsulated in a component, and their performance was tested under conditions of a pressure of 1 MPa and a temperature of room temperature. The test gases included CH4, CO2, He, and N2. The test results are shown in Table 1.

[0114] Table 1: Gas separation performance of composite hollow fiber membrane

[0115]

[0116] The Fourier transform infrared data of CoPc-TFPN-COF and CoPc-TFPN-COOH are shown in the figure Figure 2 As shown in Figure 2, the specific surface areas and pore sizes of CoPc-TFPN-COF and carboxyl-modified CoPc-TFPN-COOH are shown in Figure 2. Figure 3 As shown in Figure 3, the thermal decomposition performance of the CoPc-Mo composite hollow fiber membrane prepared in Example 3 is as follows: Figure 4 shown.

[0117] Figure 2 The Fourier transform infrared data showed that the carboxyl modification was successful, with the -1 A signal peak of -COOH appears at Figure 3 The data show that CoPc-TFPNCOF has a fixed pore size of 0.66 nm and a high specific surface area of ​​1297 m 2 / g, the carboxyl-modified CoPc-TFPN-COOH has a similar pore size of 0.64 nm and a higher specific surface area of ​​1726 m 2 / g, which makes it perform better in gas adsorption. Figure 4 The data show that the CoPc-Mo composite hollow fiber membrane has excellent temperature resistance up to 440 ° C. As can be seen from the data in Table 1, the composite hollow fiber membrane in Comparative Example 1, in which CoPc-TFPN-COOH is not added, has poor helium flux and selectivity. In Example 3, the helium flux and selectivity are greatly improved after the composite hollow fiber membrane with CoPc-TFPN-COOH is added. The maximum helium flux reaches 288GPU, and the He / CH4, He / N2 and He / CO2 selectivities reach 576, 588 and 514 respectively. And from Comparative Example 2 and Example 3, it can be seen that after the CoPc-TFPN / COF is modified with a carboxyl group and then made into a composite hollow fiber membrane, its flux and selectivity can be increased. Therefore, it can be explained that the introduction of CoPc-TFPN-COOH greatly improves the helium mass transfer resistance and improves the helium selectivity by utilizing its own structural characteristics. Among them, the composite hollow fiber membrane prepared with 0.5wt% CoPc-TFPN-COOH added in Example 3 has the best effect.

[0118] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for preparing a CoPc-Mo composite hollow fiber membrane, characterized in that: The steps include: S1: Preparation of hollow fiber ceramic membrane Weigh polyethersulfone, polyvinylpyrrolidone and N-methylpyrrolidone in sequence and add them into a three-necked flask, then add fly ash and Al2O3 to prepare a membrane casting solution, pour the membrane casting solution into a feed liquid tank, extrude the original membrane through a spinneret under nitrogen pressure, treat the original membrane to obtain membrane filaments, then place the membrane filaments into a crucible, add AlF3 and Al2O3, and then sinter in a muffle furnace to obtain a hollow fiber ceramic membrane; S2: Preparation of PDMS-Mo hollow fiber membrane The two ends of the hollow fiber ceramic base membrane are then sealed with sealant and hydroxylated to obtain a HO-Mo membrane. Polydimethylsiloxane is dissolved in n-hexane, and ethyl orthosilicate and dibutyltin dilaurate are added. The mixture is allowed to stand for 3-6 hours to pre-crosslink to form a precursor solution. The precursor solution is then dip-coated onto the HO-Mo membrane to obtain a PDMS-Mo hollow fiber membrane. S3: Preparation of CoPc-TFPN-COF and post-carboxyl modification Cobalt octahydroxyphthalocyanine and tetrafluoroterephthalonitrile were placed in an ampoule, and N,N-dimethylacetamide, mesitylene, and triethylamine were added to prepare CoPc-TFPN-COF powder. The CoPc-TFPN-COF powder and NaOH solution were added to a single-necked round-bottom flask equipped with a condenser to prepare CoPc-TFPN-COOH. S4: Preparation of CoPc-Mo composite hollow fiber membrane The method comprises the following steps: dissolving trimesoyl chloride in n-hexane to prepare an organic phase solution, dissolving cystamine dihydrochloride and NaOH in deionized water to prepare an aqueous phase solution, soaking a PDMS-Mo hollow fiber membrane in the organic phase solution to obtain a single-treatment PDMS-Mo hollow fiber membrane, adding CoPc-TFPN-COOH to the aqueous phase solution to obtain a mixed aqueous phase solution, and then soaking the single-treatment PDMS-Mo hollow fiber membrane in the mixed aqueous phase solution to obtain a CoPc-Mo composite hollow fiber membrane.

2. The method for preparing a CoPc-Mo composite hollow fiber membrane according to claim 1, characterized in that: Step S1: preparing a hollow fiber ceramic membrane, comprising the following steps: S1.1: Weigh polyethersulfone, polyvinylpyrrolidone, and N-methylpyrrolidone into a three-necked flask, add them in sequence, mechanically stir at room temperature for 1-5 hours, then heat to 60-80°C and stir until completely dissolved. Then, add fly ash and Al2O3 and stir in an oil bath at 60-80°C for 6-8 hours to form a casting solution. S1.2: Degas under vacuum at room temperature, pour the casting solution into a feed tank, extrude the original membrane through a spinneret under a nitrogen pressure of 0.1-0.5 MPa, soak the original membrane in distilled water, and replace the distilled water every 6-8 hours. After 12-24 hours, vacuum dry at 60-80°C for 6-8 hours, and cut into 5-8 cm small segments to obtain membrane filaments; S1.3: The membrane filament is placed in a crucible, and AlF3 and Al2O3 are added, and then placed in a muffle furnace for sintering by a step-by-step sintering method. In the first stage, the temperature reaches 800-1000°C after 180-240 minutes. This process promotes the decomposition of organic matter in the ceramic embryo. The temperature is kept warm for 60-80 minutes to ensure the full decomposition of the fly ash components. In the second stage, the temperature is continued to rise to 1200-1400°C and kept warm for 80-120 minutes. After the insulation is completed, it is cooled to room temperature to obtain a hollow fiber ceramic membrane.

3. The method for preparing a CoPc-Mo composite hollow fiber membrane according to claim 2, characterized in that: Step S2 prepares a PDMS-Mo hollow fiber membrane, comprising the following steps: S2.1: Seal both ends of the hollow fiber ceramic membrane with sealant, perform hydroxylation, and soak the membrane in a mixed solution of acetone:ethanol:water (volume ratio 1:1:(1-4)) for 10-30 minutes to obtain a HO-Mo membrane. S2.2: Dissolve polydimethylsiloxane in n-hexane, heat to 60-80°C and stir for 1-2 hours, then add ethyl orthosilicate and dibutyltin dilaurate, stir for 8-12 hours, and let it stand for 3-6 hours to pre-crosslink to form a precursor solution. Dip-coat the precursor solution onto the HO-Mo membrane for 1-2 hours, then place it in a vacuum oven at 40-60°C and dry it for 4-6 hours before taking it out to obtain the PDMS-Mo hollow fiber membrane.

4. The method for preparing a CoPc-Mo composite hollow fiber membrane according to claim 3, characterized in that: Step S3 Preparation of CoPc-TFPN-COF and post-carboxyl modification, including the following steps: S3.1: Place octahydroxyphthalocyanine cobalt and tetrafluoroterephthalonitrile in an ampoule, then add N,N-dimethylacetamide and mesitylene, ultrasonicate for 10-20 minutes, add triethylamine, continue ultrasonicate for 5-10 minutes, seal the glass bottle with a flame spray gun under negative pressure and liquid nitrogen freezing conditions, then place the glass bottle in an oven set at 130-150°C, heat for 60-72 hours, remove, and let it cool naturally, wash three times with N,N-dimethylacetamide, N,N-dimethylformamide, pure water, dichloromethane, and tetrahydrofuran respectively, until the filtrate is colorless, and then use tetrahydrofuran and acetone as extractants for Soxhlet extraction, each for 12-24 hours, and then dry in a vacuum at 80-120°C to obtain CoPc-TFPN-COF powder; S3.2: Add CoPc-TFPN-COF powder and 20-30% NaOH solution into a single-necked round-bottom flask equipped with a condenser. The mass ratio of CoPc-TFPN-COF and NaOH solution is 1:(220-300). Heat the mixture to 100-120°C for 3-5 days. After cooling to room temperature, a solid product is obtained. The solid product is filtered and refluxed in water for 2-6 hours, and then refluxed in 1-3 mol / L HCl for 2-6 hours. The precipitate is collected by centrifugation and rinsed with acetone, then washed with water and tetrahydrofuran, and finally Soxhlet extraction is performed with tetrahydrofuran as a solvent for 12-24 hours. The solid is collected and dried to obtain CoPc-TFPN-COOH.

5. The method for preparing a CoPc-Mo composite hollow fiber membrane according to claim 4, characterized in that: Step S4: Preparation of CoPc-Mo composite hollow fiber membrane, comprising the following steps: S4.1: Dissolve trimesoyl chloride in n-hexane to prepare an organic phase solution, then dissolve cystamine dihydrochloride and NaOH in deionized water to prepare an aqueous phase solution. Soak a PDMS-Mo hollow fiber membrane in 20-50 parts by volume of the organic phase solution for 10-60 seconds to obtain a primary treated PDMS-Mo hollow fiber membrane. S4.2: Adding CoPc-TFPN-COOH to the aqueous solution, and controlling the mass fraction of CoPc-TFPN-COOH to be 0.1-0.8%, to obtain a mixed aqueous solution; S4.3: Then, the treated PDMS-Mo hollow fiber membrane is immersed in the mixed aqueous phase solution for 3-6 minutes, rinsed with deionized water for 3-6 times, and finally dried under vacuum conditions at 60-80°C to obtain a CoPc-Mo composite hollow fiber membrane.

6. The method for preparing a CoPc-Mo composite hollow fiber membrane according to claim 5, characterized in that: The mass ratio of polyethersulfone, polyvinylpyrrolidone, N-methylpyrrolidone, fly ash and Al2O3 in step S1.1 is 9:1:(40-60):60:

20.

7. The method for preparing a CoPc-Mo composite hollow fiber membrane according to claim 6, characterized in that: Furthermore, in step S1.3, the mass ratio of the membrane filament, AlF3 and Al2O3 is (1-3):1:

1.

8. The method for preparing a CoPc-Mo composite hollow fiber membrane according to claim 7, characterized in that: In step S2.2, the mass ratio of polydimethylsiloxane, n-hexane, ethyl orthosilicate and dibutyltin dilaurate is 1:(4-8):1:

2.

9. The method for preparing a CoPc-Mo composite hollow fiber membrane according to claim 8, characterized in that: In step S3.1, the mass ratio of octahydroxyphthalocyanine cobalt, tetrafluoroterephthalonitrile, N,N-dimethylacetamide, mesitylene and triethylamine is (1-3): 1:50:50:

5.

10. The method for preparing a CoPc-Mo composite hollow fiber membrane according to claim 9, characterized in that: In step S4.1, the mass ratio of trimesoyl chloride to n-hexane is (1-5):100, and the mass ratio of cystamine dihydrochloride, NaOH, and water is (2-5):1:(200-250).

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