A porous ammonia-hydrogen separation membrane and a method for preparing the same

Abstract

The application discloses a kind of porous ammonia hydrogen separation membranes and preparation method thereof, comprising the following steps: S1, with chloromethylated polyether sulfone as raw material, it is dissolved in organic solvent, and casting membrane solution is obtained;S2, casting membrane solution is evenly coated on clean glass plate, and porous CMPES base film is obtained;S3, CMPES base film is soaked in polyamine solution and crosslinked, then it is modified by quaternary ammonium with halogenated alkane, and modified membrane is obtained;S4, modified membrane is soaked in metal chloride solution and chelation reaction is carried out to introduce adsorption site, then the membrane is taken out and repeatedly cleaned with deionized water, and porous ammonia hydrogen separation membrane is obtained.The separation membrane obtained by the application has high-efficiency ammonia separation effect, and when separating ammonia-containing gas, ammonia permeability is as high as 7777 Barrer, and ammonia / hydrogen selectivity is as high as 706.

Description

Technical Field

[0001] This invention relates to the field of new materials technology, specifically to a porous ammonia-hydrogen separation membrane and its preparation method. Background Technology

[0002] Ammonia is a compound with multiple important applications in agriculture, chemical industry, energy, medicine, and environmental protection. Currently, industrial methods for producing ammonia include natural gas-to-ammonia, heavy oil-to-ammonia, coal (coke)-to-ammonia, and the Haber-Bosch synthesis process, with the Haber-Bosch process being the mainstream industrial method. This method involves reacting hydrogen and nitrogen under high temperature and pressure to produce ammonia, but the conversion rate is relatively low, around 20%. Furthermore, the generated ammonia is mainly collected through condensation and liquefaction. Due to the presence of saturated vapor pressure, approximately 3% of the ammonia remains in the atmosphere, resulting in some product loss. In addition, ammonia is an alkaline gas with corrosive properties; therefore, large-scale ammonia emissions into the air exacerbate environmental pollution problems, making the separation and recovery of this ammonia necessary.

[0003] Common ammonia separation methods include adsorption, absorption, low-pressure distillation, and membrane separation. Among these, membrane separation has received widespread attention in recent years due to its advantages such as low energy consumption, high separation efficiency, and no environmental pollution. However, existing ammonia separation membranes have relatively low ammonia selectivity and ammonia permeation flux. To date, developing ammonia separation membranes that combine high performance and low cost remains a significant technical challenge. Summary of the Invention

[0004] To address the problems of low ammonia selectivity and low ammonia permeation flux in existing ammonia separation membranes, this invention provides a porous ammonia-hydrogen separation membrane and its preparation method. Based on the special microstructure of the porous membrane, its large free space volume greatly improves the molecular transport rate.

[0005] The present invention adopts the following technical solution:

[0006] A method for preparing a porous ammonia-hydrogen separation membrane includes the following steps:

[0007] S1. Using chloromethylated polyethersulfone (CMPES) as raw material, dissolve it in an organic solvent to obtain a casting solution;

[0008] S2. The casting solution is uniformly coated on a clean glass plate, and a porous CMPES base film is prepared by a non-solvent phase inversion method.

[0009] S3. The CMPES base film is immersed in a polyamine solution for crosslinking, and then modified by quaternization with a haloalkane to obtain a modified film.

[0010] S4. The modified membrane is immersed in a metal chloride solution to carry out a chelation reaction to introduce adsorption sites. Then the membrane is taken out and washed repeatedly with deionized water 3 times or more to obtain a porous ammonia-hydrogen separation membrane.

[0011] Preferably, in step S1, the degree of chloromethylation of CMPES is 30%-80%, and it consists of repeating units with and without chloromethyl groups, with the following structural formula:

[0012]

[0013] The organic solvent used to dissolve CMPES in step S1 is one of the following: chloroform, dichloromethane, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, 1-methylpyrrolidone, and toluene.

[0014] Preferably, the concentration of the casting solution in step S1 is 10%-40%.

[0015] The thickness of the base film in step S2 is 0.1-0.25 μm.

[0016] In step S3, the polyamine solution is an amine containing two primary or secondary amine groups.

[0017] The crosslinking conditions in step S3 are: the polyamine solution concentration is 0.1-4 mol·L⁻¹. -1 Soaking time is 0.5-48 hours, and soaking temperature is 25-80℃.

[0018] In step S3, the quaternizing reagent is a haloalkane; the quaternization modification is performed by setting the concentration of the haloalkane solution to 0.1-2 mol·L⁻¹. -1 The modification time is 0.5-48h and the temperature is 30-80℃.

[0019] Preferably, the haloalkane is one of iodomethane, bromoethane, and chloropropane.

[0020] In step S4, the metal chloride solution is one of ZnCl2, NaCl, KCl, MgCl2, LiCl2, CoCl2, NiCl2, or CuCl2.

[0021] The chelation reaction conditions in step S4 are: the concentration of the metal chloride solution is 0.1-2 mol·L⁻¹. -1 Soaking temperature is 30-120℃, soaking time is 1-48h.

[0022] A porous ammonia-hydrogen separation membrane prepared according to the above preparation method.

[0023] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0024] This invention prepares a base membrane via a solvent-free phase inversion method, which is relatively simple to form. The membrane is then cross-linked and quaternized, and finally, metal ions are introduced for chelation. The functional groups are highly tunable, allowing for the introduction of various metal ions and Lewis acids as adsorption sites. As the degree of chloromethylation of CMPES increases, more reactive groups can be introduced, further increasing the number of adsorption sites. Simultaneously, the unique porous structure of the membrane itself enhances the permeation flux of gas molecules. Detailed Implementation

[0025] This invention can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the inventive concept to those skilled in the art. All other embodiments derived by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0026] Example 1:

[0027] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0028] S1. Dissolve polyethersulfone with a chloromethylation degree of 50% in N,N-dimethylformamide to obtain a casting solution with a concentration of 30%.

[0029] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0030] S3. Immerse the CMPES base film at a temperature of 30℃ and a concentration of 1 mol·L⁻¹. -1 Crosslinking was carried out in a diethylenetriamine solution for 0.5 h, followed by immersion in a solution at 25 °C and a concentration of 0.5 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0031] S4. Immerse the modified membrane in a solution with a concentration of 0.1 mol·L⁻¹. -1 The membrane was immersed in a NiCl2 solution at 30℃ for 1 hour to carry out a chelation reaction. Then the membrane was removed and washed repeatedly with deionized water 3 times to obtain a porous ammonia-hydrogen separation membrane.

[0032] A gas mixture containing ammonia and hydrogen was separated using a gas separation device. The test results showed that the ammonia permeability was 1223.9 Barrer and the ammonia / hydrogen selectivity was 100.1.

[0033] Example 2:

[0034] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0035] S1. Dissolve polyethersulfone with a chloromethylation degree of 55% in N,N-dimethylformamide to obtain a casting solution with a concentration of 30%.

[0036] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0037] S3. Immerse the CMPES base film at a temperature of 30℃ and a concentration of 1 mol·L⁻¹. -1 Crosslinking was carried out in a triethylenetetramine solution for 3 hours, followed by immersion in a solution at 30°C with a concentration of 0.5 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0038] S4. Immerse the modified membrane in a solution with a concentration of 0.5 mol·L⁻¹. -1 The membrane was immersed in a NiCl2 solution at 35℃ for 8 hours to carry out a chelation reaction. Then the membrane was removed and washed repeatedly with deionized water 3 times to obtain a porous ammonia-hydrogen separation membrane.

[0039] A gas separation device was used to separate a mixture of ammonia and hydrogen. The test results showed that the ammonia permeability was 2231.9 Barrer and the ammonia / hydrogen selectivity was 156.8.

[0040] Example 3:

[0041] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0042] S1. Dissolve polyethersulfone with a chloromethylation degree of 30% in N,N-dimethylformamide to obtain a casting solution with a concentration of 20%.

[0043] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0044] S3. Immerse the CMPES base film at a temperature of 30℃ and a concentration of 1 mol·L⁻¹. -1Crosslinking was performed in a tetraethylenepentamine solution for 6 hours, followed by immersion in a solution at 35°C and a concentration of 1 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0045] S4. Immerse the modified membrane in a solution with a concentration of 0.5 mol·L⁻¹. -1 The membrane was immersed in a CuCl2 solution at 35℃ for 8 hours to carry out a chelation reaction. Then the membrane was removed and washed repeatedly with deionized water 3 times to obtain a porous ammonia-hydrogen separation membrane.

[0046] A gas separation device was used to separate a mixture of ammonia and hydrogen. The test results showed that the ammonia permeability was 2885 Barrer and the ammonia / hydrogen selectivity was 266.4.

[0047] Example 4:

[0048] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0049] S1. Dissolve polyethersulfone with a chloromethylation degree of 55% in N,N-dimethylformamide to obtain a casting solution with a concentration of 10%.

[0050] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0051] S3. Immerse the CMPES base film at 40℃ with a concentration of 4 mol·L⁻¹. -1 Crosslinking was carried out in a diethylenetriamine solution for 6 hours, followed by immersion in a solution at 40°C and a concentration of 0.5 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0052] S4. Immerse the modified membrane in a solution with a concentration of 0.5 mol·L⁻¹. -1 The membrane was chelated in a ZnCl2 solution at 35℃ for 12 hours. Then the membrane was removed and washed repeatedly with deionized water 4 times to obtain a porous ammonia-hydrogen separation membrane.

[0053] A gas separation device was used to separate a mixture of ammonia and hydrogen. The test results showed that the ammonia permeability was 3232.3 Barrer and the ammonia / hydrogen selectivity was 301.4.

[0054] Example 5:

[0055] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0056] S1. Dissolve polyethersulfone with a chloromethylation degree of 75% in N,N-dimethylformamide to obtain a casting solution with a concentration of 35%.

[0057] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0058] S3. Immerse the CMPES base film at 40℃ and a concentration of 2 mol·L⁻¹. -1 Crosslinking was carried out in a triethylenetetramine solution for 6 hours, followed by immersion in a solution at 45°C with a concentration of 1 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0059] S4. Immerse the modified membrane in a solution with a concentration of 0.5 mol·L⁻¹. -1 The membrane was chelated in a ZnCl2 solution at 35℃ for 12 hours. Then the membrane was removed and washed repeatedly with deionized water three times to obtain a porous ammonia-hydrogen separation membrane.

[0060] A gas separation device was used to separate a mixture of ammonia and hydrogen. The test results showed that the ammonia permeability was 3480.1 Barrer and the ammonia / hydrogen selectivity was 358.2.

[0061] Example 6:

[0062] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0063] S1. Dissolve polyethersulfone with 80% chloromethylation in N,N-dimethylformamide to obtain a casting solution with a concentration of 35%.

[0064] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0065] S3. Immerse the CMPES base film at 60℃ and a concentration of 2 mol·L⁻¹. -1 Crosslinking was carried out in a pentaethylenehexamine solution for 8 hours, followed by immersion in a solution at 45°C with a concentration of 1 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0066] S4. Immerse the modified membrane in a solution with a concentration of 2 mol·L⁻¹-1 The membrane was chelated in a CoCl2 solution at 120℃ for 48 hours. Then the membrane was removed and washed repeatedly with deionized water three times to obtain a porous ammonia-hydrogen separation membrane.

[0067] A gas separation device was used to separate a mixture of ammonia and hydrogen. The test results showed that the ammonia permeability was 3880.1 Barrer and the ammonia / hydrogen selectivity was 258.8.

[0068] Example 7:

[0069] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0070] S1. Dissolve polyethersulfone with a chloromethylation degree of 55% in N,N-dimethylformamide to obtain a casting solution with a concentration of 35%.

[0071] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0072] S3. Immerse the CMPES base film at 70℃ and a concentration of 2 mol·L⁻¹. -1 Crosslinking was performed in a diethylenetriamine solution for 10 hours, followed by immersion in a solution at 70°C with a concentration of 1 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0073] S4. Immerse the modified membrane in a solution with a concentration of 0.5 mol·L⁻¹. -1 The membrane was immersed in a CoCl2 solution at 60℃ for 16 hours to carry out a chelation reaction. Then the membrane was removed and washed repeatedly with deionized water three times to obtain a porous ammonia-hydrogen separation membrane.

[0074] A gas separation device was used to separate a mixture of ammonia and hydrogen. The test results showed that the ammonia permeability was 4586.5 Barrer and the ammonia / hydrogen selectivity was 315.

[0075] Example 8:

[0076] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0077] S1. Dissolve polyethersulfone with a chloromethylation degree of 55% in N,N-dimethylformamide to obtain a casting solution with a concentration of 35%.

[0078] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0079] S3. Immerse the CMPES base film at 70℃ and a concentration of 2 mol·L⁻¹. -1 Crosslinking was carried out in a triethylenetetramine solution for 12 hours, followed by immersion in a solution at 50°C with a concentration of 0.5 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0080] S4. Immerse the modified membrane in a solution with a concentration of 2 mol·L⁻¹ -1 The membrane was chelated in a NiCl2 solution at 60℃ for 16 hours. Then the membrane was removed and washed repeatedly with deionized water three times to obtain a porous ammonia-hydrogen separation membrane.

[0081] A gas separation device was used to separate a mixture of ammonia and hydrogen. The test results showed that the ammonia permeability was 5223.1 Barrer and the ammonia / hydrogen selectivity was 554.4.

[0082] Example 9:

[0083] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0084] S1. Dissolve polyethersulfone with a chloromethylation degree of 55% in N,N-dimethylformamide to obtain a casting solution with a concentration of 35%.

[0085] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0086] S3. Immerse the CMPES base film at 70℃ and a concentration of 4 mol·L⁻¹. -1 Crosslinking was performed in a tetraethylenepentamine solution for 20 hours, followed by immersion in a solution at 45°C with a concentration of 1 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0087] S4. Immerse the modified membrane in a solution with a concentration of 2 mol·L⁻¹ -1 The membrane was chelated in a CuCl2 solution at 80℃ for 24 hours. Then the membrane was removed and washed repeatedly with deionized water 5 times to obtain a porous ammonia-hydrogen separation membrane.

[0088] A gas separation device was used to separate a mixture of ammonia and hydrogen. The test results showed that the ammonia permeability was 6525.9 Barrer and the ammonia / hydrogen selectivity was 628.9.

[0089] Example 10:

[0090] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0091] S1. Dissolve polyethersulfone with a chloromethylation degree of 55% in N,N-dimethylformamide to obtain a casting solution with a concentration of 35%.

[0092] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0093] S3. Immerse the CMPES base film at 80℃ and a concentration of 2 mol·L⁻¹. -1 Crosslinking was carried out in a tetraethylenepentamine solution for 24 hours, followed by immersion in a solution at 50°C and a concentration of 0.5 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0094] S4. Immerse the modified membrane in a solution with a concentration of 2 mol·L⁻¹ -1 The membrane was chelated in FeCl2 solution at 80℃ for 24 hours. Then the membrane was removed and washed repeatedly with deionized water three times to obtain a porous ammonia-hydrogen separation membrane.

[0095] A gas separation device was used to separate a mixture of ammonia and hydrogen. The test results showed that the ammonia permeability was 6973.2 Barrer and the ammonia / hydrogen selectivity was 687.

[0096] Example 11:

[0097] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0098] S1. Dissolve polyethersulfone with a chloromethylation degree of 55% in N,N-dimethylformamide to obtain a casting solution with a concentration of 35%.

[0099] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0100] S3. Immerse the CMPES base film at 80℃ and a concentration of 2 mol·L⁻¹. -1 Crosslinking was carried out in a diethylenetriamine solution for 36 hours, followed by immersion in a solution at 80°C with a concentration of 1 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0101] S4. Immerse the modified membrane in a solution with a concentration of 2 mol·L⁻¹ -1 The membrane was chelated in a ZnCl2 solution at 100℃ for 36 hours. Then the membrane was removed and washed repeatedly with deionized water three times to obtain a porous ammonia-hydrogen separation membrane.

[0102] A gas separation device was used to separate a mixture of ammonia and hydrogen. The test results showed that the ammonia permeability was 7128 Barrer and the ammonia / hydrogen selectivity was 691.

[0103] Example 12:

[0104] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0105] S1. Dissolve polyethersulfone with a chloromethylation degree of 65% in N,N-dimethylformamide to obtain a casting solution with a concentration of 35%.

[0106] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0107] S3. Immerse the CMPES base film at 80℃ and a concentration of 2 mol·L⁻¹. -1 Crosslinking was carried out in a tetraethylenepentamine solution for 48 hours, followed by immersion in a solution at 50°C and a concentration of 2 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0108] S4. Immerse the modified membrane in a solution with a concentration of 2 mol·L⁻¹ -1 The membrane was immersed in a CoCl2 solution at 80℃ for 24 hours to carry out a chelation reaction. Then the membrane was removed and washed repeatedly with deionized water three times to obtain a porous ammonia-hydrogen separation membrane.

[0109] A gas separation device was used to separate a mixture of ammonia and hydrogen. The test results showed that the ammonia permeability was 7564 Barrer and the ammonia / hydrogen selectivity was 700.

[0110] Example 13:

[0111] This embodiment provides a method for preparing a porous ammonia-hydrogen separation membrane, comprising the following steps:

[0112] S1. Dissolve polyethersulfone with a chloromethylation degree of 55% in N,N-dimethylformamide to obtain a casting solution with a concentration of 30%.

[0113] S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film is prepared by a non-solvent-induced phase inversion method. Specifically, the casting solution is uniformly coated onto a glass plate, a film is scraped onto the glass plate with a doctor blade, and then the glass plate is immersed in deionized water to carry out phase inversion to obtain a CMPES porous base film.

[0114] S3. Immerse the CMPES base film at 80℃ and a concentration of 2 mol·L⁻¹. -1 Simultaneous cross-linking and quaternization were achieved by immersing the sample in a pentaethylenehexamine solution for 48 hours, followed by soaking in a solution at 50°C and a concentration of 2 mol·L⁻¹. -1 Quaternization modification was carried out in a haloalkane solution to obtain a modified film;

[0115] S4. Immerse the modified membrane in a solution with a concentration of 2 mol·L⁻¹ -1 The membrane was immersed in a CoCl2 solution at 80℃ for 24 hours to carry out a chelation reaction. Then the membrane was removed and washed repeatedly with deionized water three times to obtain a porous ammonia-hydrogen separation membrane.

[0116] A gas separation device was used to separate a mixture of ammonia and hydrogen. The test results showed that the ammonia permeability was 7777 Barrer and the ammonia / hydrogen selectivity was 706.

[0117] In summary, this invention prepares a base membrane via a solvent-free phase inversion method, which is relatively simple to form. The membrane is then cross-linked and quaternized, and finally, metal ions are introduced for chelation reactions. The functional groups are highly tunable, allowing for the introduction of various metal ions and Lewis acids as adsorption sites. As the degree of CMPES chloromethylation increases, more reactive groups can be introduced, further increasing the number of adsorption sites. Simultaneously, the unique porous structure of the membrane itself enhances the permeation flux of gas molecules.

[0118] Any aspects not described in this invention are applicable to existing technologies.

[0119] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a porous ammonia-hydrogen separation membrane, characterized in that, Includes the following steps: S1. Using chloromethylated polyethersulfone (CMPES) as raw material, dissolve it in an organic solvent to obtain a casting solution; S2. The casting solution is uniformly coated onto a clean glass plate, and a porous CMPES base film with a thickness of 0.1-0.25 µm is prepared by a non-solvent-induced phase inversion method. S3. The CMPES base film is immersed in a polyamine solution for crosslinking, and then modified by quaternization with a haloalkane to obtain a modified film. The polyamine solution is an amine containing two primary or secondary amine groups; S4. The modified membrane is immersed in a metal chloride solution to carry out a chelation reaction to introduce adsorption sites. Then, the membrane is removed and repeatedly washed with deionized water to obtain a porous ammonia-hydrogen separation membrane. The chelation reaction conditions are: the concentration of the metal chloride solution is 0.1-2 mol·L⁻¹. -1 The soaking temperature is 30-120℃, and the soaking time is 1-48h; in step S1, the degree of chloromethylation of CMPES is 30%-80%, and it is composed of repeating units with and without chloromethylation, with the following structural formula: 。 2. The preparation method according to claim 1, characterized in that: The organic solvent used to dissolve CMPES in step S1 is one of the following: chloroform, dichloromethane, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, 1-methylpyrrolidone, and toluene.

3. The preparation method according to claim 1, characterized in that: The concentration of the casting solution in step S1 is 10%-40%.

4. The preparation method according to claim 1, characterized in that: The crosslinking conditions in step S3 are: the polyamine solution concentration is 0.1-4 mol·L⁻¹. -1 Soaking time is 0.5-48 hours, and soaking temperature is 25-80℃.

5. The preparation method according to claim 1, characterized in that: In step S3, the quaternizing reagent is a haloalkane; the quaternization modification is performed by setting the concentration of the haloalkane solution to 0.1-2 mol·L⁻¹. -1 The modification time is 0.5-48h and the temperature is 30-80℃.

6. The preparation method according to claim 1, characterized in that: The haloalkane is one of iodomethane, bromoethane, and chloropropane.

7. The preparation method according to claim 1, characterized in that: In step S4, the metal chloride solution is one of ZnCl2, NaCl, KCl, MgCl2, LiCl2, CoCl2, NiCl2, or CuCl2.

8. A porous ammonia-hydrogen separation membrane prepared by the preparation method according to any one of claims 1-7.

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