PPy / PEI / HEAs polymer composite membrane as well as preparation method and application thereof

Abstract

The invention relates to the technical field of gas separation membrane materials, in particular to a PPy / PEI / HEAs polymer composite membrane as well as a preparation method and application thereof. The high-entropy alloy nanoparticles (FeMnCoNiCu-HEAs nanoparticles) synthesized by an MOF template method are used for regulating and controlling the surface of the polyethyleneimine membrane, so that the specific surface area and multi-metal active sites of the polyethyleneimine membrane are increased, and the helium separation performance of the polyethyleneimine membrane is improved. Specifically, polypyrrole is selected as a conductive polymer, and electrodeposition of high-entropy alloy nano-particle electropolymerization PPy on PEI is introduced, so that the stability of the film can be improved, and film formation and growth on the surface of the PEI film are facilitated. And meanwhile, accurate molecular sieving can be realized, and the structure and performance optimization of the gas separation membrane material is realized by regulating and controlling the microstructure through the multi-principal-element strong alloying effect of the high-entropy alloy.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation membrane materials, and particularly to PPy / PEI / HEAs polymer composite membranes and their preparation methods and applications. Background Art

[0002] Due to the low concentration of helium, the application of membrane separation technology in the field of helium extraction from natural gas is restricted to a certain extent. Membrane separation technology involves using a semi-permeable membrane as a separation medium and achieving the separation of different components by means of driving forces such as pressure difference, concentration difference, and potential difference. The improvement of high-temperature resistance, high-pressure resistance, and anti-aging performance has become a key challenge in the industrial application of membrane separation technology. Optimizing the membrane preparation process and developing high-performance gas separation membranes are the current research hotspots. Polymer membranes, especially membrane materials prepared from polymer polymers, are widely used in gas separation due to their advantages such as light weight, low cost, and simple preparation process. Organic polymers are easy to synthesize and modify and have good film-forming properties, but due to their poor high-pressure resistance, low mechanical strength, and insufficient acid-base resistance and thermal stability, it is difficult to meet the requirements of industrial applications.

[0003] To overcome the above limitations, relevant personnel are exploring various strategies, including developing new membrane materials such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs). These materials have been widely used in gas separation due to their adjustable pore structures and pore sizes, extremely high specific surface areas, and other advantages. In addition, porous organic polymers (POPs) show potential application prospects in gas adsorption and separation due to their high specific surface areas, customizable structures, adjustable pore sizes, and other characteristics. Through the innovation of these materials and the optimization of the membrane preparation process, it is expected to achieve high-performance gas separation membranes with high-temperature resistance, high-pressure resistance, and anti-aging properties to meet the strict requirements of industrial applications.

[0004] However, at present, most composite membranes are still difficult to maintain ideal selectivity and chemical stability while achieving high flux. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide PPy / PEI / HEAs polymer composite membranes and their preparation methods and applications to at least solve the problem that existing composite membranes are difficult to achieve high flux and maintain ideal selectivity and chemical stability.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] In the first aspect, an embodiment of the present application provides a preparation method of a PPy / PEI / HEAs polymer composite membrane, including the following steps:

[0008] The polyethyleneimine film was wound and fixed on stainless steel, and then clamped on a platinum electrode clip as the working electrode. A stainless steel sheet was used as the counter electrode, and a saturated calomel electrode was used as the reference electrode to construct a three-electrode system;

[0009] The pyrrole monomer was dispersed and dissolved in deionized water with stirring to obtain a first electrolyte solution; a part of the first electrolyte solution was mixed with an aqueous sulfuric acid solution, and FeMnCoNiCu-HEAs nanoparticles were added, and ultrasonic dispersion was carried out at room temperature to obtain a second electrolyte solution;

[0010] In the first electrolyte solution, deposition was carried out at a current density of 0.4 - 0.6 mA / cm 2 for 0.5 - 1 h, and then in the second electrolyte solution, deposition was carried out at a current density of 0.1 - 0.4 mA / cm 2 for 1.5 - 3 h. The polyethyleneimine film on the stainless steel was removed, washed with deionized water, and dried to obtain a PPy / PEI / HEAs composite film;

[0011] The PPy / PEI / HEAs composite film was stabilized in an aqueous polyethylene glycol solution to obtain a stable PPy / PEI / HEAs polymer composite film.

[0012] Furthermore, the preparation method of the FeMnCoNiCu-HEAs nanoparticles is as follows:

[0013] Weigh ferric nitrate and dissolve it in methanol, then add N,N-dimethylformamide and stir to obtain a first solution with a ferric nitrate concentration of 0.07 - 0.1 mol / L;

[0014] Weigh cobalt nitrate, manganese nitrate, nickel nitrate, copper nitrate and 2-methylimidazole respectively, dissolve them in methanol, add a terephthalic acid solution, stir and mix, and carry out ultrasonic dispersion treatment to obtain a second solution;

[0015] The second solution was dropped into the first solution at a rate of 2 - 3 drops per second, and continuous stirring was carried out for 20 - 24 h. The precipitate product obtained from the third solution was centrifuged and collected, washed with methanol, and dried to obtain a metal precursor loaded with MOF;

[0016] The metal precursor loaded with MOF was heated at a rate of 5 - 7 °C / min and maintained at 900 - 950 °C for 2.5 - 3 hours in a 10% H2 / Ar atmosphere to obtain FeMnCoNiCu-HEAs nanoparticles.

[0017] Furthermore, the molar ratio of ferric nitrate, cobalt nitrate, manganese nitrate, nickel nitrate, and copper nitrate is 1:1:1:1:1.

[0018] Further, the molar ratio of cobalt nitrate to 2-methylimidazole is (8-10):(36.5-42.6), and the molar ratio of copper nitrate to terephthalic acid is (2-2.5):1.

[0019] Further, the concentration of pyrrole monomer in the first electrolyte is 0.01-0.05 mol / L; the concentration of FeMnCoNiCu-HEAs nanoparticles in the second electrolyte is 0.1-0.3 g / L.

[0020] Further, the sulfuric acid concentration of the sulfuric acid aqueous solution is 0.5 mol / L, and the first electrolyte and the sulfuric acid aqueous solution are mixed evenly according to a volume ratio of (0.002-0.003):1.

[0021] Further, the concentration of the polyethylene glycol aqueous solution is 2-5 wt%.

[0022] Further, the stabilization treatment is carried out as follows:

[0023] Immerse the PPy / PEI / HEAs composite membrane in the polyethylene glycol aqueous solution for 3-5 min, take it out and remove the free solution on the membrane surface, and then place it in a constant temperature drying oven at a temperature of 50-60 °C and a humidity of 30%-40% for drying to obtain a stable PPy / PEI / HEAs polymer composite membrane.

[0024] In a second aspect, an embodiment of the present application also provides a PPy / PEI / HEAs polymer composite membrane, which is prepared by using the preparation method described in the first aspect above.

[0025] In a third aspect, an embodiment of the present application also provides the application of the PPy / PEI / HEAs polymer composite membrane described in the second aspect above in a helium separation membrane.

[0026] The preparation method of the PPy / PEI / HEAs polymer composite membrane of the present invention uses high-entropy alloy nanoparticles (FeMnCoNiCu-HEAs nanoparticles) synthesized by the MOF template method to regulate the surface of the polyethyleneimine membrane, increase its specific surface area and multi-metal active sites, and improve its helium separation performance. Specifically, polypyrrole is selected as the conductive polymer, and the electropolymerization of PPy by introducing high-entropy alloy nanoparticles can increase the stability of the membrane and is beneficial to film hanging and growth on the surface of the PEI membrane. At the same time, precise molecular sieving can also be achieved, and the structure and performance of the gas separation membrane material are optimized by using the microstructure regulation effect of the multi-principal element strong alloying effect of the high-entropy alloy. Description of the Drawings

[0027] Figure 1 is a schematic structural diagram of a three-electrode system;

[0028] Figure 2 It is a test result diagram of the anti-plasticization performance of the composite film of Example 3;

[0029] Figure 3 It is a test result diagram of the anti-plasticization performance of the composite film of Comparative Example 2. Detailed implementation manners

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0031] The terms "first", "second", etc. in the specification and claims of this article are used to distinguish different objects, rather than to describe a specific order of the objects. In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0032] The English letter interpretations in the present invention are as follows:

[0033] PEI: Polyethyleneimine; Py: Pyrrole monomer; PPy: Polypyrrole; SCE: Saturated calomel electrode; PEG: Polyethylene glycol; DMF: N,N-Dimethylformamide; TAA: Terephthalic acid.

[0034] Electrodeposition technology can be used to produce conductive polymer films. The obtained films have good chemical stability. Compared with traditional film-making methods, the organic films prepared by the electrodeposition-assisted strategy show good separation performance and excellent stability in long-term gas tests. To improve the chemical stability and gas selectivity of the film, in the present application, high-entropy alloy nanoparticles (FeMnCoNiCu-HEAs nanoparticles) synthesized by the MOF template method are used to regulate the surface of the polyethyleneimine film, increase its specific surface area and multi-metal active sites, and improve its helium separation performance. Specifically, polypyrrole is selected as the conductive polymer, and the electropolymerization of PPy by introducing high-entropy alloy nanoparticles in the electrodeposition of PEI can increase the stability of the film, which is beneficial to the film formation and growth on the surface of the PEI film. At the same time, it can also achieve precise molecular sieving, and use the multi-principal-element strong alloying effect of the high-entropy alloy to regulate the microstructure to optimize the structure and performance of the gas separation membrane material.

[0035] The PPy / PEI / HEAs polymer composite membrane of the present application includes a membrane base layer and a membrane outer layer. The membrane base layer is a polyethyleneimine film, and the membrane outer layer is a composite membrane of electro-polymerized PPy and FeMnCoNiCu-HEAs nanoparticles on the membrane base layer, and it is a polymer composite membrane with lamellar nanomaterials.

[0036] Specifically, the preparation method of the PPy / PEI / HEAs polymer composite membrane of the present application is as follows:

[0037] Wind and fix the polyethyleneimine membrane on stainless steel, then clamp it on a platinum electrode clip as the working electrode, use a stainless steel sheet as the counter electrode, and use a saturated calomel electrode as the reference electrode to construct a three-electrode system. Please refer to Figure 1 ; Disperse pyrrole monomer into deionized water and stir to dissolve to obtain a first electrolyte solution; Take a part of the first electrolyte solution and mix it with a sulfuric acid aqueous solution, and add FeMnCoNiCu-HEAs nanoparticles, and ultrasonically disperse it at room temperature to obtain a second electrolyte solution; In the first electrolyte solution, deposit at a current density of 0.4 - 0.6 mA / cm 2 for 0.5 - 1 h, and then deposit in the second electrolyte solution at a current density of 0.1 - 0.4 mA / cm 2 for 1.5 - 3 h. The membrane on the stainless steel is denoted as PPy / PEI-X-Y, where X represents the number of types of electrolyte solutions, and Y represents the total electrodeposition time. Remove the polyethyleneimine membrane on the stainless steel, wash it with deionized water, and then dry it in an oven at 30 - 40 °C to obtain the PPy / PEI / HEAs composite membrane; Stabilize the PPy / PEI / HEAs composite membrane in an aqueous solution of polyethylene glycol to obtain a stable PPy / PEI / HEAs polymer composite membrane.

[0038] Among them, the molar ratio of iron nitrate, cobalt nitrate, manganese nitrate, nickel nitrate, and copper nitrate is 1:1:1:1:1. The concentration of pyrrole monomer in the first electrolyte solution is 0.01 - 0.05 mol / L; The concentration of FeMnCoNiCu-HEAs nanoparticles in the second electrolyte solution is 0.1 - 0.3 g / L. The sulfuric acid concentration of the sulfuric acid aqueous solution is 0.5 mol / L, and the first electrolyte solution and the sulfuric acid aqueous solution are mixed evenly according to a volume ratio of (0.002 - 0.003):1.

[0039] Among them, the concentration of the aqueous solution of polyethylene glycol is 2 - 5 wt%. The stabilization treatment operation is as follows: Immerse the PPy / PEI / HEAs composite membrane in the aqueous solution of polyethylene glycol for 3 - 5 min, take it out and remove the free solution on the membrane surface, and then dry it in a constant temperature drying oven at a temperature of 50 - 60 °C and a humidity of 30% - 40% to obtain a stable PPy / PEI / HEAs polymer composite membrane.

[0040] Among them, the preparation method of FeMnCoNiCu-HEAs nanoparticles is as follows:

[0041] Weigh ferric nitrate and dissolve it in methanol, then add N,N-dimethylformamide and stir to obtain a first solution with a ferric nitrate concentration of 0.07 - 0.1 mol / L; respectively weigh cobalt nitrate, manganese nitrate, nickel nitrate, copper nitrate and 2-methylimidazole and dissolve them in methanol, and add terephthalic acid solution, stir and mix, and perform ultrasonic dispersion treatment to obtain a second solution; drop the second solution into the first solution at a rate of 2 - 3 drops per second, continuously stir for 20 - 24 h, centrifuge the obtained third solution to collect the precipitate product, wash it with methanol, and after drying, obtain a metal precursor loaded with MOF; heat the metal precursor loaded with MOF at a rate of 5 - 7 °C / min and keep it at 900 - 950 °C for 2.5 - 3 h in a 10% H2 / Ar atmosphere to obtain FeMnCoNiCu-HEAs nanoparticles. In the preparation method of FeMnCoNiCu-HEAs nanoparticles, the molar ratio of ferric nitrate, cobalt nitrate, manganese nitrate, nickel nitrate, and copper nitrate is 1:1:1:1:1, the molar ratio of cobalt nitrate to 2-methylimidazole is (8 - 10):(36.5 - 42.6), and the molar ratio of copper nitrate to terephthalic acid is (2 - 2.5):1.

[0042] To better understand the above technical solution, the above technical solution will be described in detail below in combination with the accompanying drawings of the specification and specific embodiments.

[0043] Example 1

[0044] The preparation method of the PPy / PEI / HEAs polymer composite membrane in this example is as follows:

[0045] (1) Construct a three-electrode system

[0046] Take the cut 2 cm 2 PEI membrane, rinse it repeatedly with deionized water and dry it. Rub the surface of the stainless steel sheet with sandpaper to remove the surface oxide, then rinse it repeatedly with deionized water and ethanol and dry it for standby. Wind and fix the PEI membrane on the stainless steel with insulating tape, and then clamp it on the platinum electrode clip as the working electrode, use the stainless steel sheet as the counter electrode, and use the saturated calomel electrode as the reference electrode to construct a three-electrode system, please refer to Figure 1 .

[0047] (2) Prepare the electrolyte

[0048] Disperse Py in deionized water and stir to dissolve it to obtain a first electrolyte solution with a concentration of 0.04 mol / L. Measure 0.14 ml of the first electrolyte solution and add it to 50 ml of a sulfuric acid aqueous solution with a concentration of 0.5 mol / L, and magnetically stir for 30 min to completely dissolve it. Subsequently, add 0.010 g of FeMnCoNiCu-HEAs nanoparticles and ultrasonically treat it at room temperature to disperse it evenly to obtain a stable second electrolyte solution.

[0049] (3) Preparation of composite film

[0050] Deposit polypyrrole on the surface of the PEI film in two steps by constant current electrochemical method. First, deposit in the second electrolyte solution at a current density of 0.5 mA / cm 2 for 1 h, and then continue to deposit in the second electrolyte solution at a current density of 0.25 mA / cm 2 for 2.5 h, with a total deposition time of 3.5 h. Remove the polyethyleneimine film on the stainless steel and denote it as PPy / PEI / HEAs-1-3.5. Wash the deposited film repeatedly with deionized water to remove surface contaminants, and place the prepared film in an oven at 30 °C to dry to obtain the PPy / PEI / HEAs-1-3.5 composite film.

[0051] (4) Stabilization treatment

[0052] Weigh PEG and add it to deionized water, and stir to dissolve it at room temperature to obtain a PEG aqueous solution with a concentration of 4 wt%. Immerse the above-prepared PPy / PEI / HEAs-1-3.5 composite film in the PEG aqueous solution for 4 min, take it out and remove the free solution on the film surface, and place the film in a constant temperature drying oven at 60 °C and a humidity of 40% to dry overnight to obtain a stable PPy / PEI / HEAs-1-3.5 polymer composite film.

[0053] Example 2

[0054] The preparation method of the PPy / PEI / HEAs polymer composite film in this example is as follows:

[0055] (1) Construction of three-electrode system

[0056] This step is exactly the same as that in Example 1.

[0057] (2) Preparation of electrolyte solution

[0058] This step is exactly the same as that in Example 1.

[0059] (3) Preparation of composite film

[0060] Deposit polypyrrole on the surface of the PEI film in two steps by constant current electrochemical method. First, deposit in the first electrolyte solution at a current density of 0.5 mA / cm 2Deposit for 1 h, and then continue to deposit in the second electrolyte at a current density of 0.25 mA / cm 2 Deposit for 2.5 h, with a total deposition time of 3.5 h. Remove the polyethyleneimine film on the stainless steel, denoted as PPy / PEI / HEAs-2-3.5. Wash the deposited film repeatedly with deionized water to remove surface contaminants, and place the prepared film in an oven at 30 °C to dry, obtaining the PPy / PEI / HEAs-2-3.5 composite film.

[0061] Example 3

[0062] The preparation method of the PPy / PEI / HEAs polymer composite film in this example is as follows:

[0063] (1) Construct a three-electrode system

[0064] This step is exactly the same as that in Example 1.

[0065] (2) Prepare the electrolyte

[0066] This step is exactly the same as that in Example 1.

[0067] (3) Prepare the composite film

[0068] Deposit polypyrrole on the surface of the PEI film in two steps by the constant current electrochemical method. First, deposit in the first electrolyte at a current density of 0.5 mA / cm 2 Deposit for 1 h, and then continue to deposit in the second electrolyte at a current density of 0.25 mA / cm 2 Deposit for 2.5 h, with a total deposition time of 3.5 h. Remove the polyethyleneimine film on the stainless steel, denoted as PPy / PEI / HEAs-2-3.5. Wash the deposited film repeatedly with deionized water to remove surface contaminants, and place the prepared film in an oven at 30 °C to dry, obtaining the PPy / PEI / HEAs-2-3.5 composite film.

[0069] (4) Stabilization treatment

[0070] Weigh PEG and add it to deionized water, stir and dissolve at room temperature to obtain a PEG aqueous solution with a concentration of 4 wt%. Immerse the above-prepared PPy / PEI / HEAs-2-3.5 composite film in the PEG aqueous solution for 4 min, take it out and remove the free solution on the film surface, and place the film in a constant temperature drying oven at 60 °C and a humidity of 40% to dry overnight, thereby obtaining a stable PPy / PEI / HEAs-2-3.5 polymer composite film.

[0071] Example 4

[0072] The preparation method of the PPy / PEI / HEAs polymer composite film in this example is as follows:

[0073] (1) Construct a three - electrode system

[0074] This step is exactly the same as that in Example 1.

[0075] (2) Prepare the electrolyte

[0076] Disperse Py in deionized water and stir to dissolve it to obtain a first electrolyte with a concentration of 0.01 mol / L. Measure 0.10 ml of the first electrolyte and add it to 50 ml of a sulfuric acid aqueous solution with a concentration of 0.5 mol / L, and stir magnetically for 30 min to completely dissolve it. Then add 5 mg of FeMnCoNiCu - HEAs nanoparticles and ultrasonically treat it at room temperature to disperse it evenly to obtain a stable second electrolyte.

[0077] (3) Prepare the composite membrane

[0078] Deposit polypyrrole on the surface of the PEI membrane in two steps by the constant - current electrochemical method. First, deposit for 0.5 h in the first electrolyte at a current density of 0.4 mA / cm 2 Then continue to deposit for 1.5 h in the second electrolyte at a current density of 0.1 mA / cm 2 The total deposition time is 2 h. Remove the polyethyleneimine membrane on the stainless steel, denoted as PPy / PEI / HEAs - 2 - 2. Wash the deposited membrane repeatedly with deionized water to remove surface contaminants, and place the prepared membrane in an oven at 35 °C to dry to obtain the PPy / PEI / HEAs - 2 - 2 composite membrane.

[0079] (4) Stabilization treatment

[0080] Weigh PEG and add it to deionized water, and stir to dissolve it at room temperature to obtain a PEG aqueous solution with a concentration of 2 wt%. Immerse the above - prepared PPy / PEI / HEAs - 2 - 2 composite membrane in the PEG aqueous solution for 3 min, take it out and remove the free solution on the membrane surface, and place the membrane in a constant - temperature drying oven at a temperature of 50 °C and a humidity of 30% to dry overnight, thereby obtaining a stable PPy / PEI / HEAs - 2 - 2 polymer composite membrane.

[0081] Example 5

[0082] The preparation method of the PPy / PEI / HEAs polymer composite membrane in this example is as follows:

[0083] (1) Construct a three - electrode system

[0084] This step is exactly the same as that in Example 1.

[0085] (2) Prepare the electrolyte

[0086] Disperse Py in deionized water and stir to dissolve it to obtain a first electrolyte solution with a concentration of 0.05 mol / L. Measure 0.15 ml of the first electrolyte solution and add it to 50 ml of a sulfuric acid aqueous solution with a concentration of 0.5 mol / L, and magnetically stir for 30 min to completely dissolve it. Then add 15 mg of FeMnCoNiCu-HEAs nanoparticles and ultrasonically treat it at room temperature to disperse it evenly to obtain a stable second electrolyte solution.

[0087] (3) Preparation of composite film

[0088] Deposit polypyrrole on the surface of the PEI film in two steps by the constant current electrochemical method. First, deposit in the first electrolyte solution at a current density of 0.6 mA / cm 2 for 0.6 h, and then continue to deposit in the second electrolyte solution at a current density of 0.4 mA / cm 2 for 3 h, with a total deposition time of 3.6 h. Remove the polyethyleneimine film on the stainless steel, denoted as PPy / PEI / HEAs-2-3.6. Wash the deposited film repeatedly with deionized water to remove surface contaminants, and place the prepared film in an oven at 40 °C to dry to obtain the PPy / PEI / HEAs-2-3.6 composite film.

[0089] (4) Stabilization treatment

[0090] Weigh PEG and add it to deionized water, and stir to dissolve it at room temperature to obtain a PEG aqueous solution with a concentration of 5 wt%. Immerse the above-prepared PPy / PEI / HEAs-2-3.6 composite film in the PEG aqueous solution for 5 min, take it out and remove the free solution on the film surface, and place the film in a constant temperature drying oven at a temperature of 55 °C and a humidity of 35% to dry overnight to obtain a stable PPy / PEI / HEAs-2-3.6 polymer composite film.

[0091] Comparative example 1

[0092] The difference between this comparative example and Example 2 lies in the step of preparing the composite film. The one-step deposition method is adopted, that is, deposit in the first electrolyte solution at a current density of 0.25 mA / cm 2 for 3.5 h, remove the polyethyleneimine film on the stainless steel, wash the deposited film repeatedly with deionized water to remove surface contaminants, and place the prepared film in an oven at 30 °C to dry to obtain the PPy / PEI composite film.

[0093] Comparative example 2

[0094] The difference between this comparative example and Example 3 lies in the steps of constructing the three-electrode system. First, the PEI film after cleaning and drying is immersed in a PEG solution with a concentration of 4 wt% for 4 minutes. Then, the PEI film is wound and fixed on stainless steel with electrical insulating tape and clamped on the platinum electrode clip as the working electrode, with a stainless steel sheet as the counter electrode and a saturated calomel electrode as the reference electrode to construct the three-electrode system, and there is no stabilization treatment step at the end of Example 3. Other steps are the same as those in Example 3, and finally, the PPy / PEI / HEAs polymer composite film is obtained.

[0095] Performance test:

[0096] The composite films prepared in Examples 1-5 and Comparative Examples 1-2 were cut and encapsulated in a test assembly for gas separation performance testing. The test pressure was set at 0.4 Mpa and the temperature was at room temperature. The retentate side and the permeate side were purged with argon. The test gases were CH4, He, CO2, and N2. The test results are shown in Table 1. Using the ternary mixed gases He / CO2 / CH4 and He / CO2 / N2 as the feed gases respectively, the anti-plasticization performance of the composite films prepared in Example 3 and Comparative Example 2 was tested by controlling the feed pressure. For the test results of the anti-plasticization performance of the composite film in Example 3, please refer to Figure 2 , and for the test results of the anti-plasticization performance of the composite film in Comparative Example 2, please refer to Figure 3 .

[0097]

[0098] Table 1

[0099] The data in Table 1 show that the PPy / PEI / HEAs polymer composite membrane has a high helium flux and helium selectivity. The helium flux can reach 375 GPU, and the selectivities of He / CH4, He / N2, and He / CO2 can reach 357, 335, and 379 respectively. It is found from the comparison in Table 1 that the PPy / PEI / HEAs-2-3.5 composite membrane prepared in Example 2 has a lower helium flux, only 101 GPU, and the He / CH4 selectivity is only 47. This indicates that the stabilized PPy / PEI / HEAs polymer composite membrane can play an efficient role in gas transmission and has excellent gas selectivity. In Example 1, a two-step electrodeposition was carried out using an electrolyte (the second electrolyte), and the PPy / PEI / HEAs-1-3.5 composite membrane prepared is weaker than the PPy / PEI / HEAs polymer composite membrane in Example 3 both in terms of helium flux and helium selectivity, indicating that the choice of electrolyte during electrodeposition has a great influence on the flux and selectivity of the composite membrane. The composite membrane in Comparative Example 1 does not have FeMnCoNiCu-HEAs nanoparticles, and its helium flux and selectivity are quite different from those in Example 3, indicating that FeMnCoNiCu-HEAs nanoparticles can improve the helium flux and selectivity of the composite membrane.

[0100] It can be seen from Figure 2 that as the feed pressure increases, the helium selectivity does not decrease significantly. However, from Figure 3 the detection of the anti-plasticization performance of the composite membrane in Comparative Example 2, it is found that the increase in feed pressure will significantly reduce the helium selectivity and increase the helium flux, indicating that for the composite membrane in Comparative Example 2, as the pressure increases, the polymer chains in the membrane structure will shift, so it does not have good anti-plasticization performance, suggesting that first electro-polymerize FeMnCoNiCu-HEAs nanoparticles and Py solution on the composite membrane substrate and then carry out stabilization treatment will endow the polymer composite membrane with excellent anti-plasticization performance.

[0101] In summary, the PPy / PEI / HEAs polymer composite membrane prepared by the preparation method of this application, which introduces FeMnCoNiCu-HEAs nanoparticles, has a high helium flux and helium selectivity, as well as excellent anti-plasticization performance, and can be used as a gas separation membrane for the separation and purification of helium.

[0102] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention. The technologies, shapes, and structures not described in detail in the present invention are all well-known technologies.

Claims

1. Preparation method of PPy / PEI / HEAs polymer composite film, characterized in that, It includes the following steps: Wind and fix the polyethyleneimine membrane on stainless steel, then clamp it on the platinum electrode clip as the working electrode, use the stainless steel sheet as the counter electrode, and use the saturated calomel electrode as the reference electrode to construct a three-electrode system; Disperse pyrrole monomer into deionized water and stir to dissolve it to obtain the first electrolyte; Take a part of the first electrolyte and mix it with sulfuric acid aqueous solution, and add FeMnCoNiCu-HEAs nanoparticles, and ultrasonically disperse it at room temperature to obtain the second electrolyte; Deposit for 0.5 - 1 h in the first electrolyte at a current density of 0.4 - 0.6 mA / cm 2 Then deposit for 1.5 - 3 h in the second electrolyte at a current density of 0.1 - 0.4 mA / cm 2 Remove the polyethyleneimine film on the stainless steel, wash it with deionized water, dry it, and obtain the PPy / PEI / HEAs composite film; Stabilize the PPy / PEI / HEAs composite membrane in an aqueous polyethylene glycol solution to obtain a stable PPy / PEI / HEAs polymer composite membrane.

2. The preparation method of the PPy / PEI / HEAs polymer composite membrane according to claim 1, wherein, The preparation method of the FeMnCoNiCu-HEAs nanoparticles is as follows: Weigh ferric nitrate and dissolve it in methanol, then add N,N-dimethylformamide and stir to obtain a first solution with a ferric nitrate concentration of 0.07 - 0.1 mol / L; Weigh cobalt nitrate, manganese nitrate, nickel nitrate, copper nitrate and 2-methylimidazole respectively and dissolve them in methanol, and add terephthalic acid solution, stir and mix, and perform ultrasonic dispersion treatment to obtain a second solution; Drop the second solution into the first solution at a rate of 2 - 3 drops per second, continuously stir for 20 - 24 h, centrifuge the obtained third solution to collect the precipitate product, wash it with methanol, and after drying, obtain a metal precursor loaded with MOF; Heat the metal precursor loaded with MOF at a rate of 5 - 7 °C / min and keep it at 900 - 950 °C for 2.5 - 3 hours in a 10% H2 / Ar atmosphere to obtain FeMnCoNiCu-HEAs nanoparticles.

3. The preparation method of the PPy / PEI / HEAs polymer composite membrane according to claim 2, characterized in that, The molar ratio of ferric nitrate, cobalt nitrate, manganese nitrate, nickel nitrate, and copper nitrate is 1:1:1:1:

1.

4. The preparation method of the PPy / PEI / HEAs polymer composite film according to claim 3, wherein The molar ratio of cobalt nitrate to 2-methylimidazole is (8 - 10):(36.5 - 42.6), and the molar ratio of copper nitrate to terephthalic acid is (2 - 2.5):

1.

5. The preparation method of the PPy / PEI / HEAs polymer composite film according to claim 1, wherein The concentration of pyrrole monomer in the first electrolyte is 0.01 - 0.05 mol / L; The concentration of FeMnCoNiCu-HEAs nanoparticles in the second electrolyte is 0.1 - 0.3 g / L.

6. The preparation method of the PPy / PEI / HEAs polymer composite membrane according to claim 5, characterized in that, The sulfuric acid concentration of the sulfuric acid aqueous solution is 0.5 mol / L, and the first electrolyte and the sulfuric acid aqueous solution are mixed evenly according to the volume ratio of (0.002 - 0.003):

1.

7. The preparation method of the PPy / PEI / HEAs polymer composite membrane according to claim 1, characterized in that, The concentration of the aqueous polyethylene glycol solution is 2 - 5 wt%.

8. The preparation method of the PPy / PEI / HEAs polymer composite film according to claim 7, characterized in that, The stabilization treatment operation is as follows: Immerse the PPy / PEI / HEAs composite membrane in the aqueous polyethylene glycol solution for 3 - 5 min, take it out and remove the free solution on the membrane surface, and then place it in a constant temperature drying oven at a temperature of 50 - 60 °C and a humidity of 30% - 40% to dry, to obtain a stable PPy / PEI / HEAs polymer composite membrane.

9. A PPy / PEI / HEAs polymer composite membrane, characterized in that, The PPy / PEI / HEAs polymer composite membrane is prepared by the preparation method described in any one of claims 1 - 8.

10. The application of the PPy / PEI / HEAs polymer composite membrane according to claim 9 in a helium separation membrane.

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