A metal-containing single-atom molecular sieve carbon membrane with high hydrogen selectivity and a preparation method thereof

Abstract

The present application relates to a kind of metal atom-containing molecular sieve carbon membrane with high hydrogen selectivity and its preparation method, belong to membrane separation field and new material field.A kind of metal atom-containing molecular sieve carbon membrane with high hydrogen selectivity, the carbon membrane is obtained by high-temperature carbonization of metal atom-containing polymer membrane, wherein, the metal atom-containing polymer for preparing polymer membrane is prepared by the following method: carrier is activated and grafted functional group is mixed with the alcohol solution of metal salt, obtain metal atom-containing carrier;Metal atom-containing carrier, polymer monomer, catalyst, organic solvent are mixed uniformly according to certain proportion, with nitrogen as protective gas, reflux stirring at a certain temperature for a certain time, pour into water after cooling, obtain metal atom-containing polymer.The carbon membrane of the present application introduces the single atom of iron, nickel, palladium, platinum and the like with adsorption effect to hydrogen, has higher atomic utilization, catalytic activity and hydrogen adsorption performance.

Description

Technical Field

[0001] The present invention relates to a metal-containing single-atom molecular sieve carbon membrane with high hydrogen selectivity and a preparation method thereof, and belongs to the fields of membrane separation and new materials. Background Art

[0002] With the continuous depletion of fossil fuels, hydrogen, as a renewable green energy source, is gaining increasing attention. Currently, hydrogen primarily comes from the decomposition of biomass, water, and fossil fuels. However, regardless of the method used, the production process inevitably produces impurities such as N2, CH4, H2O, and CO2. Therefore, the separation and purification of hydrogen is particularly important. Among the many separation methods, membrane separation technology has attracted widespread attention due to its advantages such as environmental friendliness, simple operation, and ease of integration with other chemical separation processes.

[0003] Molecular sieve carbon membrane is a new type of inorganic membrane material made by high-temperature pyrolysis of carbon-containing substances in an inert atmosphere or vacuum environment. It has good thermal and chemical stability, high gas separation selectivity, and can effectively separate small molecular mixed gases with similar molecular sizes, showing unique advantages in hydrogen separation. However, due to the "worm-like" pore structure of the molecular sieve carbon membrane, the gas diffusion channel is narrow and lengthy, and the gas permeability of the pure carbon membrane is often poor. In order to solve this problem, researchers introduced metals with hydrogen adsorption activity into the polymer precursor to prepare metal-containing molecular sieve carbon membranes to improve the permeability of the carbon membrane to hydrogen. Among them, how to select suitable polymers and metals, improve the dispersion of metals inside the membrane, and reduce the non-selective defects introduced by the poor compatibility between the polymer and metal phases are the key to preparing a complete and defect-free molecular sieve carbon membrane. Summary of the Invention

[0004] To solve the above problems, the present invention improves the hydrogen separation performance of molecular sieve carbon membranes by introducing single atoms of iron, nickel, palladium, platinum, etc. that have an adsorption effect on hydrogen into the molecular sieve carbon membrane. Compared with traditional technologies, the metal exists in the form of single atoms, which has higher atomic utilization, catalytic activity and hydrogen adsorption performance; the metal atoms are fixed on the carrier through the defective coordination environment and spatial constraint provided by the carrier, which effectively improves the dispersion of the metal atoms; the carrier loaded with single atoms participates in the polymerization reaction as a polymerization monomer after grafting functional groups to form a metal single atom-containing polymer, which has good compatibility with the polymer body and can reduce the generation of non-selective defects during the membrane preparation and carbonization process. These characteristics are of great significance for the industrial application of high-performance hydrogen separation carbon membranes.

[0005] The present invention provides a method for preparing a metal-containing single-atom molecular sieve carbon membrane with high hydrogen selectivity, which can effectively improve the molecular sieve carbon membrane's ability to separate hydrogen, solve the problems of poor metal dispersion and poor compatibility at the two-phase interface, and prepare a defect-free molecular sieve carbon membrane with both high flux and high selectivity.

[0006] The present invention is achieved through the following technical solutions:

[0007] A metal single atom-containing molecular sieve carbon membrane with high hydrogen selectivity, wherein the carbon membrane is obtained by high-temperature carbonization of a metal single atom-containing polymer membrane, wherein the metal single atom-containing polymer used to prepare the polymer membrane is prepared according to the following method:

[0008] The carrier is activated and grafted with functional groups, and then mixed with an alcohol solution of a metal salt, and then stirred, centrifuged, washed, and dried to obtain a carrier containing metal single atoms; the carrier containing metal single atoms, a polymer monomer, a catalyst, and an organic solvent are uniformly mixed in a certain ratio, nitrogen is used as a protective gas, refluxed and stirred at a certain temperature for a certain time, and then poured into water after cooling, and filtered, washed, and dried to obtain a polymer containing metal single atoms.

[0009] In the above technical solution, the carrier is one of ZIF-8, ZIF-90, MIL-53, UiO-66, MOF-74, COF-102, COF-103, COF-202, graphene oxide, and C3N4, and its size is between 5nm and 500nm.

[0010] In the above technical solution, the functional group is one or more of hydroxyl, fluoro, amino, and carboxyl groups, and the corresponding grafting reagent is one or more of 3-methoxysilane propanol, trifluoropropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, and carboxypropyltrimethoxysilane.

[0011] Furthermore, the ratio of the grafting agent to the carrier is 2.1 mol / 1 mol to 2.5 mol / 1 mol.

[0012] In the above technical solution, the metal salt is one or more of iron salt, nickel salt, palladium salt and platinum salt.

[0013] Furthermore, the ratio of the metal salt to the carrier is 1g / 20g to 1g / 40g.

[0014] Furthermore, the metal salt is an inorganic salt of a metal, such as nitrate, chloride, sulfate, etc.

[0015] In the above technical solution, the polymer monomer is one or more of 4,4'-difluorobenzophenone, phenolphthalein, 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, 4,4'-difluorodiphenyl sulfide, bisphenol A, and acrylonitrile.

[0016] In the above technical solution, the catalyst is one or more of sodium carbonate, potassium carbonate, potassium hydroxide, triethylamine, and pyridine.

[0017] Furthermore, the ratio of the polymer monomer to the organic solvent is 1 mol / 200 ml, and the added amount of the carrier is 5-30% of the solid content.

[0018] Preferably, the carrier is dispersed in an activation solvent under ultrasonic conditions, mechanically stirred at 60° C. for 5 to 18 hours, then heated under reduced pressure at 100 to 150° C. overnight, and placed in a vacuum drying oven to remove the solvent to obtain an activated carrier; the activated carrier is dissolved in anhydrous ethanol under ultrasonic conditions, a grafting agent is added thereto according to a certain ratio, mechanically stirred at room temperature for 6 to 24 hours to ensure sufficient reaction, the product is centrifuged and washed with ethanol multiple times; the metal salt is dissolved in anhydrous ethanol, the grafted carrier is added in batches under ultrasonic conditions, mechanically stirred at 60° C. for 6 to 18 hours, reduced pressure for 2 to 8 hours, the product is centrifuged and washed with ethanol multiple times to obtain a carrier containing metal single atoms,

[0019] In which, the activation solvent is one or more of methanol, ethanol, and acetone; the ratio of the activation solvent to the carrier is 400 ml / g; the ratio of anhydrous ethanol to the activated carrier is 200 ml / 1 g; the ratio of the grafting agent to the carrier is 2.1 mol / 1 mol to 2.5 mol / 1 mol, preferably 2.15 mol / 1 mol; the ratio of the metal salt to the carrier is 1 g / 20 g to 1 g / 40 g; and the ratio of the metal salt to anhydrous ethanol is 1 g / 400 ml.

[0020] In the above technical scheme, the carrier containing metal single atoms, polymer monomers, catalysts, and organic solvents are mixed uniformly in a certain ratio and ultrasonically stirred for 2 to 3 hours to ensure uniform mixing; then nitrogen is introduced into the resulting solution as a protective gas, heated to 180 to 220°C, refluxed and stirred for 5 to 48 hours, and slowly poured into water after cooling to room temperature. The precipitate obtained by filtration is washed with distilled water 3 to 8 times, placed in a vacuum drying oven, and dried at 100 to 150°C for 12 hours to obtain a polymer containing metal single atoms.

[0021] The above technical solution also includes the steps of preparing the polymer into a polymer film and carbonizing the polymer film.

[0022] Specifically, a polymer containing metal single atoms is dissolved in an organic solvent in a certain ratio, heated, stirred, centrifuged, and degassed to obtain a casting liquid, which is cast on a flat plate to form a liquid film of a certain thickness. After the solvent is evaporated and vacuum dried, a polymer film is obtained; the polymer film is heated from room temperature to the final temperature at a certain heating rate in an inert atmosphere, kept constant at this temperature for a period of time, and then cooled in the furnace to obtain a carbon film.

[0023] Furthermore, a polymer containing metal single atoms is dissolved in an organic solvent at a mass fraction of 10 to 20% and stirred at 25 to 100° C. for 4 to 12 hours. Impurities are removed by centrifugation in a high-speed centrifuge, and then degassing is performed in a vacuum drying oven at room temperature. Thereafter, the casting liquid is cast on a flat plate to form a liquid film of a certain thickness. The flat plate with the liquid film is placed in a dry environment at 30 to 100° C. to evaporate the solvent for 12 to 18 hours to form a film, and then placed in a vacuum drying oven and dried at 100 to 150° C. for 12 hours to obtain a polymer film containing metal single atoms.

[0024] Furthermore, the polymer membrane containing metal single atoms is cut into membrane sheets of a certain size and placed in a carbonization furnace. In an inert atmosphere, the temperature is raised from room temperature to 600-1000°C at a heating rate of 1-10°C / min and kept constant at this temperature for 1-24 hours to obtain a molecular sieve carbon membrane containing metal single atoms.

[0025] Furthermore, the inert atmosphere is one or more of nitrogen, argon, and helium atmospheres.

[0026] A preferred technical solution of the present invention is:

[0027] A method for preparing a metal-containing single-atom molecular sieve carbon membrane with high hydrogen selectivity comprises the following steps:

[0028] (1) Preparation of a support containing a metal atom: Activate the support and graft functional groups onto it, then mix it with an alcohol solution of a metal salt, stir, centrifuge, wash, and dry it.

[0029] (2) Preparation of metal single atom-containing polymers: The metal single atom-containing carrier, polymer monomer, catalyst, and organic solvent are uniformly mixed in a certain ratio, and nitrogen is used as a protective gas. The mixture is refluxed and stirred at a certain temperature for a certain time. After cooling, the mixture is poured into water, filtered, washed, and dried to obtain the polymer.

[0030] (3) Preparation of metal single atom-containing polymer membrane: The polymer is dissolved in an organic solvent according to a certain ratio, heated and stirred, centrifuged, and degassed to obtain a casting solution, which is then cast on a flat plate to form a liquid film of a certain thickness, which is then evaporated and vacuum dried to obtain the film;

[0031] (4) Preparation of metal-containing single-atom molecular sieve carbon membrane: The polymer membrane is heated from room temperature to the final temperature at a certain heating rate in an inert atmosphere, kept constant at this temperature for a period of time, and then cooled in the furnace.

[0032] The beneficial effects of the present invention are as follows: the carbon membrane of the present invention introduces single atoms of iron, nickel, palladium, platinum, and other materials that have a hydrogen adsorption effect, resulting in higher atomic utilization, catalytic activity, and hydrogen adsorption performance; the metal atoms are fixed to the carrier through the defective coordination environment and spatial constraints provided by the carrier, effectively improving the dispersion of the metal atoms; and the carrier loaded with single atoms participates in the polymerization reaction as a polymerization monomer after being grafted with functional groups, showing good compatibility with the polymer host and reducing the generation of non-selective defects during the membrane formation and carbonization processes. These characteristics are of great significance for the industrial application of high-performance hydrogen separation carbon membranes. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The SEM image of the surface of the polyaryletherketone-based molecular sieve carbon membrane and the distribution of C, O, and Fe elements show that the surface structure of the molecular sieve carbon membrane is dense and the Fe element is evenly distributed in it.

[0034] Figure 2 This is the SEM image of the surface of the polyimide-based molecular sieve carbon membrane and the distribution diagram of C, O, and Ni elements. The surface structure of the molecular sieve carbon membrane is dense and the Ni element is evenly distributed in it. DETAILED DESCRIPTION

[0035] The following non-limiting examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0036] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are all commercially available unless otherwise specified.

[0037] A method for preparing a metal-containing single-atom molecular sieve carbon membrane with high hydrogen selectivity comprises the following steps:

[0038] 1 Preparation of metal single atom-containing supports

[0039] (1) Activation of carrier

[0040] The carrier is dispersed in the organic solution under ultrasonic conditions, mechanically stirred for a certain period of time, heated under reduced pressure overnight, and placed in a vacuum drying oven to remove the solvent.

[0041] (2) Grafting of carrier

[0042] The obtained carrier is added with a functionalizing reagent in a certain ratio to graft functional groups, mixed evenly, and reacted at room temperature for a certain time. The product is separated by centrifugation and washed with ethanol for multiple times.

[0043] (3) Functionalization of carriers

[0044] The obtained support is mixed with an alcohol solution of a metal salt under ultrasonic conditions, and the support containing metal single atoms is obtained after mechanical stirring, centrifugal separation and washing.

[0045] 2 Preparation of polymers containing metal single atoms

[0046] The metal single atom-containing carrier, polymer monomer, catalyst, and organic solvent are mixed evenly in a certain ratio, nitrogen is introduced as a protective gas, refluxed and stirred at a certain temperature for a certain time, and then slowly poured into water after cooling and filtered. The resulting precipitate is washed with distilled water and dried in a vacuum drying oven to obtain a polymer containing metal single atoms.

[0047] 3 Preparation of polymer films containing metal single atoms

[0048] The polymer containing metal single atoms is dissolved in an organic solvent at a certain mass fraction, heated and stirred for a period of time, centrifuged using a high-speed centrifuge to remove impurities, and degassed in a vacuum drying oven. The casting liquid is then cast on a flat plate to form a liquid film of a certain thickness, placed in a dry environment at a certain temperature to evaporate the solvent, and placed in a vacuum drying oven for drying to obtain a polymer film containing metal single atoms.

[0049] 4 Preparation of Metal-Containing Single-Atom Molecular Sieve Carbon Membranes

[0050] The polymer film is cut into sheets of a certain size and placed in a carbonization furnace. The temperature is raised from room temperature to the final temperature at a certain rate in an inert atmosphere, kept constant for a period of time, and then cooled in the furnace to obtain a molecular sieve carbon film containing metal single atoms.

[0051] In the above technical solution, the organic solution in step 1 is one or more of methanol, ethanol, and acetone, the mechanical stirring time is 5 to 18 hours, and the reduced pressure heating temperature is 100 to 150°C.

[0052] In the above technical solution, the carrier in step 1 is one of ZIF-8, ZIF-90, MIL-53, UiO-66, MOF-74, COF-102, COF-103, COF-202, graphene oxide, and C3N4, and its size is between 5nm and 500nm.

[0053] In the above technical solution, the functional group in step 1 is one or more of a hydroxyl group, a fluoro group, an amino group, and a carboxyl group, and the corresponding grafting reagent is one or more of 3-methoxysilane propanol, trifluoropropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, and carboxypropyltrimethoxysilane.

[0054] In the above technical solution, the certain ratio in step 1 is that the material ratio of anhydrous ethanol to the carrier is 200 ml / 1 g, and the material ratio of the grafting agent to the carrier is 2.1 mol / 1 mol to 2.5 mol / 1 mol.

[0055] In the above technical solution, the reaction period in step 1 is 6 to 24 hours of mechanical stirring at room temperature.

[0056] In the above technical solution, the metal salt in step 1 is one or more of iron salt, nickel salt, palladium salt, and platinum salt. The alcohol solution of the metal salt is prepared by dissolving the metal salt in ethanol according to a certain mass ratio. The material ratio of the metal salt to the ethanol is 1g / 400ml, and the material ratio of the metal salt to the carrier is 1g / 20g to 1g / 40g.

[0057] In the above technical solution, the temperature condition of heating and stirring in step 1 is 60° C. and the time is 16 to 18 hours.

[0058] In the above technical solution, the polymer monomer in step 2 is one or more of 4,4'-difluorobenzophenone, phenolphthalein, 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, 4,4'-difluorodiphenyl sulfide, bisphenol A, acrylonitrile, etc., and the prepared polymer belongs to one of polyaryletherketone, polyimide, polyethersulfone, polyacrylonitrile, etc. The material ratio of the polymer monomer and the organic solvent is 1 mol / 200 ml, and the amount of the carrier added is 5 to 30% of the solid content.

[0059] In the above technical solution, the condition of reflux stirring at a certain temperature for a certain time in step 2 is heating to 180-220° C. and reflux stirring for 5-48 hours.

[0060] In the above technical solution, the washing operation in step 2 is washing with distilled water 3 to 8 times, the purpose of which is to remove unreacted raw materials and low molecular weight by-products.

[0061] In the above technical solution, the drying condition in step 2 is to place the product in a vacuum drying oven and dry it at 100°C to 150°C for 12 hours.

[0062] In the above technical solution, the mass ratio in step 3 is the mass fraction of the high molecular weight polymer: 5% to 30%.

[0063] In the above technical solution, the solvent is evaporated in step 3 at a temperature of 30 to 100° C., with an environmental requirement of a relative humidity of less than 30% RH, and an evaporation time of 12 to 18 hours.

[0064] In the above technical solution, the vacuum degree of the vacuum drying in step 3 is -0.2 to -0.8 bar, the temperature is 100° C. to 150° C., and the drying time is 24 hours.

[0065] In the above technical solution, in step 4, the high-temperature carbonization under an inert atmosphere is performed, the inert gas is one or more of nitrogen, argon, helium, etc., the gas flow rate is 300-1000 ml / min, the heating rate is 1-10°C / min, the final temperature is 600-1000°C, and the constant temperature time is 1-24h.

[0066] Example 1:

[0067] In this example, FeCl3·6H2O was used as the metal source and ZIF-8 was used as the support. ZIF-8 was first dispersed in anhydrous methanol under ultrasonic conditions, mechanically stirred at 60°C for 12 hours, then heated at 120°C under reduced pressure overnight and dried in a vacuum drying oven. The support was dissolved in anhydrous ethanol under ultrasonic conditions, and 3-methoxysilane propanol (MPS) was added to it in a certain ratio to graft hydroxyl groups. The ratio of anhydrous ethanol to support was 200ml / 1g, and the ratio of MPS to support was 2.15mol / 1mol. Mechanical stirring was carried out at room temperature. The product was centrifuged and washed several times with ethanol. FeCl3·6H2O and ethanol were mixed at a ratio of 1g:400ml, and the resulting support was added in batches under ultrasonic conditions. The ratio of FeCl3·6H2O to ZIF-8 was 1g / 20g. After mechanical stirring at 60°C for 18 hours, the pressure was reduced for 5 hours, and the solution was centrifuged. The product was washed three times with ethanol and dried. The carrier, 4,4'-difluorobenzophenone, phenolphthalein, anhydrous sodium carbonate (Na2CO3), and xylene were then mixed uniformly in a ratio of 1.05 mol:1 mol:2 mol:200 ml. Nitrogen was introduced as a protective gas, and the mixture was heated to 200°C, refluxed, and stirred for 5-48 hours. After cooling to room temperature, the mixture was slowly poured into water. The filtered precipitate was washed six times with distilled water and dried in a vacuum drying oven to obtain a polymer. The resulting polymer was dissolved in N,N-dimethylacetamide at a mass fraction of 18%, stirred at 80°C for 12 hours, and the solution was centrifuged in a high-speed centrifuge to remove impurities. The solution was then degassed in a vacuum drying oven to obtain a polymer solution. The precursor solution was then cast onto a flat plate to form a nascent liquid film. The film was then transferred to a dry environment to evaporate the solvent and dried in a vacuum drying oven to obtain a polymer film. The polymer membrane was cut into membrane sheets of a certain size and placed in a carbonization furnace. Under a nitrogen atmosphere, the temperature was raised from room temperature to 800°C at a rate of 3°C / min, kept constant for 5 hours, and then cooled in the furnace to obtain a molecular sieve carbon membrane.

[0068] Comparative Example 1:

[0069] A molecular sieve carbon membrane was prepared according to the experimental method of Example 1, except that the support was activated and grafted but not functionalized (i.e., no metal atoms were introduced). The gas permeation separation performance of the membrane is shown in Table 1.

[0070] Comparative Example 2:

[0071] The molecular sieve carbon membrane was prepared by directly mixing the metal salt with the polymer monomers and other raw materials without adding a carrier. The gas permeation separation performance of the membrane is shown in Table 1.

[0072] Comparative Example 3:

[0073] The molecular sieve carbon membrane was prepared by directly mixing the polymer monomers and other raw materials to form a conventional polymer membrane according to the experimental method of Example 1, except that no carrier or metal salt was added. The gas permeation separation performance of the membrane is shown in Table 1.

[0074] Table 1

[0075]

[0076] Example 2:

[0077] The experimental method of Example 1 was followed, except that the prepared polymer was a polyimide, the grafted functional group was changed to an amine group, the grafting reagent was changed to 3-aminopropyltriethoxysilane (APTMS), and the polymer monomers were changed to 4,4'-diaminodiphenyl ether and pyromellitic dianhydride. The ratio of 4,4'-diaminodiphenyl ether to pyromellitic dianhydride was 1.05 mol:1 mol. The gas permeation properties of the membrane are shown in Table 2.

[0078] Example 3:

[0079] The experimental method of Example 1 was followed, except that the prepared polymer was a polyimide, and the monomers were 4,4'-difluorodiphenyl sulfide and bisphenol A, with the ratio of 4,4'-difluorodiphenyl sulfide to bisphenol A being 1.05 mol:1 mol. The gas permeation properties of the membrane are shown in Table 2.

[0080] Example 4:

[0081] The experimental method of Example 1 was followed, except that the prepared polymer was polyacrylonitrile and the monomer was changed to acrylonitrile. The gas permeability of the membrane is shown in Table 2.

[0082] Table 2

[0083]

[0084] Example 5:

[0085] The experimental method of Example 1 was followed, except that the amount of the functionalized carrier introduced during the preparation process was 30 wt.%. The gas permeation separation performance of the prepared molecular sieve carbon membrane is shown in Table 3.

[0086] Example 6:

[0087] According to the experimental method of Example 3, the difference from Example 3 is that the amount of the functionalized carrier introduced during the preparation process is 20 wt.%. The gas permeation separation performance of the prepared molecular sieve carbon membrane is shown in Table 3.

[0088] Examples 7 to 9:

[0089] The experimental method of Example 1 was followed, except that the metal source was changed to one of NiCl2·6H2O, PtCl4·6H2O, and PdCl2·6H2O. The gas permeation separation performance of the prepared molecular sieve carbon membrane is shown in Table 3.

[0090] Table 3

[0091]

[0092] Examples 10 to 14:

[0093] The experimental method of Example 1 was followed, except that the support was changed to one of ZIF-8, ZIF-90, MIL-53, UiO-66, MOF-74, COF-102, COF-103, COF-202, graphene oxide, or C3N4. The gas permeation separation performance of the prepared molecular sieve carbon membrane is shown in Table 4.

[0094] Table 4

[0095]

Claims

1. A metal-containing single-atom molecular sieve carbon membrane with high hydrogen selectivity, wherein the carbon membrane is obtained by high-temperature carbonization of a metal-containing single-atom polymer membrane, wherein: The metal single atom-containing polymer used to prepare the polymer film was prepared as follows: The carrier is activated and grafted with functional groups, and then mixed with an alcohol solution of a metal salt, and stirred, centrifuged, washed, and dried to obtain a carrier containing metal single atoms; the carrier containing metal single atoms, a polymer monomer, a catalyst, and an organic solvent are uniformly mixed in a certain ratio, nitrogen is used as a protective gas, refluxed and stirred at a certain temperature for a certain time, poured into water after cooling, filtered, washed, and dried to obtain a polymer containing metal single atoms, wherein the functional group is one or more of hydroxyl, fluoro, amino, and carboxyl groups, and the corresponding grafting reagent is one or more of 3-methoxysilane propanol, trifluoropropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, and carboxypropyltrimethoxysilane; and the metal salt is one or more of iron salt, nickel salt, palladium salt, and platinum salt.

2. The carbon membrane according to claim 1, characterized in that The carrier is one of ZIF-8, ZIF-90, MIL-53, UiO-66, MOF-74, COF-102, COF-103, COF-202, graphene oxide, and C3N4.

3. The carbon membrane according to claim 1, characterized in that The polymer monomer is one or more of 4,4'-difluorobenzophenone, phenolphthalein, 4,4'-diaminodiphenyl ether, pyromellitic dianhydride, 4,4'-difluorodiphenyl sulfide, bisphenol A, and acrylonitrile; the catalyst is one or more of sodium carbonate, potassium carbonate, potassium hydroxide, triethylamine, and pyridine; and the ratio of the polymer monomer to the organic solvent is 1 mol / 200 ml.

4. The carbon membrane according to claim 1, characterized in that The activation method of the carrier is as follows: the carrier is dispersed in the activation solvent under ultrasonic conditions, mechanically stirred at 60°C for 5 to 18 hours, then heated at 100 to 150°C under reduced pressure overnight, and placed in a vacuum drying oven to remove the solvent to obtain an activated carrier; the grafting functional group method is as follows: the activated carrier is dissolved in anhydrous ethanol under ultrasonic conditions, a grafting reagent is added thereto according to a certain ratio, mechanically stirred at room temperature for 6 to 24 hours to ensure sufficient reaction, the product is centrifuged and washed with ethanol multiple times; the preparation method of the carrier containing metal single atoms is as follows: the metal salt is dissolved in anhydrous ethanol, the grafted carrier is added in batches under ultrasonic conditions, mechanically stirred at 60°C for 6 to 18 hours, reduced pressure for 2 to 8 hours, the product is centrifuged and washed with ethanol multiple times to obtain the carrier containing metal single atoms. The activation solvent is one or more of methanol, ethanol, and acetone; the ratio of the activation solvent to the carrier is 400 ml / 1 g; the ratio of anhydrous ethanol to the activated carrier is 200 ml / 1 g; the ratio of the grafting agent to the carrier is 2.1 mol / 1 mol to 2.5 mol / 1 mol; the ratio of the metal salt to the carrier is 1 g / 20 g to 1 g / 40 g; and the ratio of the metal salt to anhydrous ethanol is 1 g / 400 ml.

5. The carbon membrane according to claim 1, characterized in that The carrier containing metal single atoms, polymer monomer, catalyst, and organic solvent are mixed uniformly in a certain ratio and ultrasonically stirred for 2 to 3 hours to ensure uniform mixing; then nitrogen is introduced into the resulting solution as a protective gas, heated to 180 to 220°C, refluxed and stirred for 5 to 48 hours, and then slowly poured into water after cooling to room temperature. The filtered precipitate is washed with distilled water 3 to 8 times, placed in a vacuum drying oven, and dried at 100 to 150°C for 12 hours to obtain a polymer containing metal single atoms.

6. The carbon membrane according to claim 1, characterized in that A polymer containing metal single atoms is dissolved in an organic solvent in a certain ratio, heated, stirred, centrifuged, and degassed to obtain a casting liquid, which is cast on a flat plate to form a liquid film of a certain thickness. The polymer film is obtained after solvent evaporation and vacuum drying. The polymer film is heated from room temperature to the final temperature at a certain heating rate in an inert atmosphere, kept constant for a period of time, and then cooled in the furnace to obtain a carbon film.

7. The carbon membrane according to claim 6, characterized in that A polymer containing metal single atoms is dissolved in an organic solvent at a mass fraction of 10-20% and stirred at 25-100°C for 4-12 hours. Impurities are removed by centrifugation in a high-speed centrifuge, and then degassing is performed in a vacuum drying oven at room temperature. The casting liquid is then cast on a flat plate to form a liquid film of a certain thickness. The flat plate with the liquid film is placed in a dry environment at 30-100°C to evaporate the solvent for 12-18 hours to form a film. The film is then placed in a vacuum drying oven and dried at 100-150°C for 12 hours to obtain a polymer film containing metal single atoms.

8. The carbon membrane according to claim 6, characterized in that The polymer membrane containing metal single atoms is cut into membrane sheets of a certain size and placed in a carbonization furnace. In an inert atmosphere, the temperature is raised from room temperature to 600~1000℃ at a rate of 1~10℃ / min and kept constant at this temperature for 1~24h to obtain a molecular sieve carbon membrane containing metal single atoms.

9. A method for preparing a metal-containing single-atom molecular sieve carbon membrane with high hydrogen selectivity, comprising the following steps: (1) Preparation of a support containing a metal atom: The support is activated and grafted with a functional group, and then mixed with an alcohol solution of a metal salt, stirred, centrifuged, washed, and dried to obtain the support. The functional group is one or more of hydroxyl, fluoro, amino, and carboxyl groups, and the corresponding grafting reagent is one or more of 3-methoxysilane propanol, trifluoropropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, and carboxypropyltrimethoxysilane; the metal salt is one or more of iron salt, nickel salt, palladium salt, and platinum salt; (2) Preparation of metal single atom-containing polymers: The metal single atom-containing carrier, polymer monomer, catalyst, and organic solvent are mixed uniformly in a certain ratio, and nitrogen is used as a protective gas. The mixture is refluxed and stirred at a certain temperature for a certain time. After cooling, the mixture is poured into water, filtered, washed, and dried to obtain the polymer. (3) Preparation of polymer membrane containing metal single atoms: The polymer is dissolved in an organic solvent according to a certain ratio, heated and stirred, centrifuged, and degassed to obtain a casting solution, which is then cast on a flat plate to form a liquid film of a certain thickness, which is then evaporated and vacuum dried to obtain the film; (4) Preparation of metal-containing single-atom molecular sieve carbon membrane: The polymer membrane is heated from room temperature to the final temperature at a certain heating rate in an inert atmosphere, kept constant at this temperature for a period of time, and then cooled in the furnace.

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