A composite film material and a preparation method and application thereof

Abstract

The present application relates to the technical field of separation membrane material, and discloses a composite membrane material, a preparation method and application thereof.The composite membrane material comprises, from bottom to top, a porous metal support layer, a transition buffer layer and a high-entropy alloy separation layer.The high-entropy alloy separation layer comprises the following mass percentage of elements: Co: 10-25%, Fe: 10-25%, Cr: 5-20%, Al: 5-10%, V: 1-5%, Pd: 1-3% and the balance of Ni.The present application effectively solves the problems of high cost, easy cracking, low service life and high difficulty in membrane preparation process of hydrogen separation membranes in the prior art.

Description

Technical Field

[0001] This invention relates to the field of separation membrane materials technology, and in particular to a composite membrane material, its preparation method, and its application. Background Technology

[0002] Hydrogen is a fundamental gas in key areas such as chemical synthesis (ammonia synthesis, hydrocracking, hydrorefining), metallurgical reduction (direct reduction of iron), and energy (fuel cell vehicles / distributed power generation). Its applications are widespread, and its preparation, storage, and separation technologies are currently hot research topics. Hydrogen separation technology is a crucial link, directly impacting the efficiency and cost of the hydrogen energy industry chain. Common sources of hydrogen-containing gas mixtures in industry include, but are not limited to: natural gas steam reforming, methanol reforming, gases from coal gasification / water-gas conversion, tail gas from heavy oil hydrocracking, refinery circulating hydrogen, by-product gas from methanol-to-olefins units, and backflow circulating gas from renewable energy-driven electrolysis units. These gas streams often contain complex impurities besides hydrogen, such as carbon monoxide, carbon dioxide, methane, nitrogen, water vapor, hydrogen sulfide, carbonyl sulfide, and ammonia. In traditional processes, hydrogen post-treatment and purification include pressure swing adsorption (PSA), cryogenic separation, or membrane separation. Among these, membrane separation technology, due to its advantages of simple operation, low energy consumption, and environmental friendliness, has become the core research direction for hydrogen separation.

[0003] Existing hydrogen separation membranes are mainly noble metal membranes, such as palladium-based membranes (Pd membranes or Pd-Ag membranes) or transition metal membranes (V membranes or Nb membranes). Palladium-based dense membranes utilize the extremely high selective permeability of Pd and its alloys to hydrogen molecules, achieving near-"single-product" hydrogen permeation at medium and high temperatures, meaning the permeate side is almost entirely hydrogen. Therefore, Pd-Ag membranes are considered ideal materials for producing high-purity hydrogen for fuel cells. However, palladium-based membranes are very expensive, and their surfaces are easily covered or chemically adsorbed by species such as CO, H2S, thiols, or halogens, leading to the occupation of hydrogen molecule dissociation sites and a sharp decrease in hydrogen flux. In addition, palladium-based membranes are prone to cracking during use, resulting in a short lifespan, which is not conducive to large-scale use. Transition metals and their alloys theoretically have high solubility and high diffusion rates for hydrogen, possessing extremely high hydrogen flux potential. However, transition metals are highly susceptible to hydrogen embrittlement, especially at lower temperatures or during cooling stages, where the material may experience embrittlement and membrane failure due to hydrogen solid solution / precipitation, and the membrane fabrication process is also more difficult.

[0004] Therefore, developing a membrane material with high hydrogen flux, unaffected by toxic impurities, long lifespan, and simple process is of great practical significance for the field of hydrogen separation. Summary of the Invention

[0005] In view of this, the present invention provides a composite membrane material, its preparation method, and its application. The composite membrane material comprises, from bottom to top, a porous metal support layer, a transition buffer layer, and a high-entropy alloy separation layer. These three layers work synergistically to achieve efficient hydrogen separation, effectively solving the problems of high cost, easy cracking, short service life, and high difficulty in membrane fabrication of existing hydrogen separation membranes.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a composite membrane material, which comprises, from bottom to top, a porous metal support layer, a transition buffer layer, and a high-entropy alloy separation layer; wherein the high-entropy alloy separation layer comprises the following elemental composition by mass percentage: Co: 10%-25%, Fe: 10%-25%, Cr: 5%-20%, Al: 5%-10%, V: 1%-5%, Pd: 1%-3%, and the balance Ni.

[0008] Compared to existing technologies, this invention designs a composite membrane material comprising, from bottom to top: a porous metal support layer, a transition buffer layer, and a high-entropy alloy separation layer. These three layers work synergistically to achieve efficient hydrogen separation. The porous metal support layer forms the framework of the composite membrane material, providing a stable deposition substrate for the high-entropy alloy separation layer and ensuring the structural stability of the composite membrane material during cyclic use at high temperatures. Furthermore, the interconnected pore structure of the porous metal support layer allows for uniform diffusion of the mixed gas into the high-entropy alloy separation layer, reducing gas flow resistance, optimizing hydrogen throughput, and improving separation efficiency. The transition buffer layer, located between the support layer and the separation layer, is a crucial bridge for enhancing the stability and separation performance of the composite membrane. It not only reduces interfacial mismatch between the support and separation layers but also enhances interfacial adhesion through chemical bonding or physical adsorption, preventing separation layer detachment or defects such as pinholes and cracks during use. Additionally, the transition buffer layer prevents excessive permeation of the separation layer material into the pores of the support layer, reducing mass transfer resistance.

[0009] The high-entropy alloy separation layer is the core functional layer of the composite membrane material. Utilizing the multi-component synergistic effect of the high-entropy alloy, it regulates the lattice structure and electronic properties, promoting hydrogen adsorption and diffusion. The high-entropy alloy separation layer also inhibits metal atom migration, enhancing its resistance to carbon deposition and oxidation. In the high-entropy alloy separation layer provided by this invention, Ni, Co, and Fe can provide dissociation sites for hydrogen molecules, promoting the dissociation of molecular hydrogen into atomic hydrogen, further increasing the hydrogen diffusion rate; Pd can promote the recombination of atomic hydrogen after permeation into hydrogen molecules, assisting in improving surface permeation efficiency. Furthermore, Pd can reduce the hydrogen solubility of the alloy, improve the hydrogen embrittlement resistance of the high-entropy alloy separation layer, and extend its service life. In this invention, Pd can also play a catalytic role as a minor element, avoiding the high cost problem caused by the scarcity of Pd resources in traditional Pd-based membranes. V has a large atomic radius, and when it forms a solid solution with elements such as Cr and Al, it causes lattice distortion, affecting the diffusion barrier of hydrogen atoms and thus optimizing hydrogen permeation efficiency. The presence of Cr can reduce hydrogen solubility and reduce the formation of brittle hydrides. At the same time, Cr forms a dense oxide film on the alloy surface, improving the corrosion resistance of the membrane in acidic or high-temperature environments. Moreover, Cr, V, and Pd synergistically regulate the alloy phase composition, ensuring the continuity of hydrogen permeation channels. The introduction of Al reduces the density of the membrane material, meeting the structural strength and lightweight requirements of the membrane module. In addition, Al easily forms an alumina layer on the surface, which can act as a natural protective layer to reduce the loss of precious metals such as Pd. At the same time, the introduction of Al may induce subsurface amorphization, promote hydrogen atom adsorption and diffusion, and enhance surface activity.

[0010] Preferably, the thickness of the porous metal support layer is 0.5-1 mm.

[0011] Preferably, the thickness of the transition buffer layer is 5-20 μm.

[0012] Preferably, the thickness of the high-entropy alloy separation layer is 2-10 μm.

[0013] Preferably, the porosity of the porous metal support layer is 35%-40%, and the average pore size is 0.3-0.5μm.

[0014] Preferably, the surface roughness of the transition buffer layer is ≤200nm.

[0015] Preferably, the porous metal support layer is made of an Fe-Cr-Al alloy.

[0016] Preferably, the material of the transition buffer layer is a Ni / Al2O3 composite material.

[0017] A second aspect of the present invention provides a method for preparing the composite membrane material, specifically comprising the following steps:

[0018] Step 1: Fe-Cr-Al alloy powder is extruded and drawn to form a hollow blank tube. Under an inert atmosphere, the hollow blank tube is heated to 1150-1200℃, kept at the temperature, and then cooled to form a porous metal support layer.

[0019] Step 2: Mix the nickel salt solution and the alumina precursor colloid evenly to obtain a mixed sol; immerse the porous metal support layer in the mixed sol, dry it, and sinter it in a reducing atmosphere to obtain the composite membrane material precursor;

[0020] Step 3: Weigh the metal raw materials of the high-entropy alloy separation layer according to the design ratio, and deposit the separation layer on the composite membrane material precursor by multi-target magnetron co-sputtering in an inert atmosphere. Anneal the material to obtain the composite membrane material.

[0021] Preferably, in step one, the temperature is raised to 1150-1200℃ using a programmed temperature rise method, with a heating rate of 3-5℃ / min.

[0022] Preferably, in step one, the heat preservation time is 1-3 hours.

[0023] Preferably, in step one, cooling is performed using a programmed cooling method, with a cooling rate of 5-10℃ / min.

[0024] Preferably, in step two, the concentration of the nickel salt solution is 0.5-1 mol / L.

[0025] Preferably, in step two, the alumina precursor colloid is AlOOH sol.

[0026] Preferably, in step two, the reducing atmosphere is a hydrogen atmosphere.

[0027] Preferably, in step two, the mass ratio of the nickel salt solution to the alumina precursor colloid is 1:1 to 1:2.

[0028] Preferably, in step two, the sintering temperature is 650-800℃.

[0029] Preferably, in step two, the sintering time is 0.5-2 hours.

[0030] Preferably, in step three, the pressure of the multi-target magnetron co-sputtering is 0.5-1.5 Pa, and the substrate temperature is 350-450 °C.

[0031] Preferably, in step three, the annealing process is carried out in a reducing atmosphere.

[0032] Preferably, in step three, the annealing process is carried out in a hydrogen atmosphere.

[0033] Preferably, in step three, the annealing temperature is 700-800℃ and the annealing time is 0.5-3h.

[0034] A third aspect of the present invention provides the application of the composite membrane material in the field of hydrogen separation.

[0035] Preferably, the composite membrane material is used for hydrogen separation in a tubular form, with hydrogen entering through a porous metal membrane and escaping through a high-entropy alloy separation layer.

[0036] Preferably, the purity of the hydrogen separated by the composite membrane material is ≥99.999%.

[0037] In summary, the composite membrane material provided by this invention utilizes the synergistic effect of a porous metal support layer, a transition buffer layer, and a high-entropy alloy separation layer to successfully achieve efficient separation of hydrogen-gas mixtures. Furthermore, the composite membrane material has low preparation cost, a simple preparation process, and a long service life, effectively overcoming the shortcomings of existing technologies and providing a new design approach for hydrogen separation. Attached Figure Description

[0038] Figure 1 This is a cross-sectional scanning electron microscope (SEM) structural diagram of the composite membrane material obtained in Example 1;

[0039] Figure 2 This is a magnified scanning electron microscope (SEM) structural diagram of the cross-section of the composite membrane material obtained in Example 1;

[0040] Figure 3 This is a scanning electron microscope (SEM) schematic diagram of the outer surface structure of the composite membrane material obtained in Example 1. Detailed Implementation

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] This embodiment provides a composite membrane material and its preparation method, the details of which are as follows:

[0044] The composite membrane material comprises, from bottom to top: a 0.78 mm thick porous Fe-Cr-Al alloy layer, a 15 μm thick Ni / Al2O3 composite material layer, and an 8 μm thick high-entropy alloy separation layer; wherein, the high-entropy alloy separation layer comprises the following elemental composition by mass percentage: Co: 22%, Fe: 25%, Cr: 18%, Al: 6%, V: 4%, Pd: 2%, and the balance Ni.

[0045] The preparation method of the composite membrane material includes the following steps:

[0046] Step 1: The Fe-Cr-Al alloy powder is extruded and drawn to form a hollow blank tube. Under an inert atmosphere, the hollow blank tube is heated to 1180°C at a heating rate of 5°C / min and held for 2 hours. Then it is cooled to room temperature at a cooling rate of 10°C / min to form a porous metal support layer.

[0047] Step 2: Mix 0.8 mol / L nickel nitrate solution and AlOOH sol at a mass ratio of 1:1.5 to obtain a mixed sol; immerse the porous metal support layer in the mixed sol, dry it, and sinter it at 700°C for 1.5 h under a hydrogen atmosphere to obtain the precursor of the composite membrane material;

[0048] Step 3: Weigh the metal raw materials of the high-entropy alloy separation layer according to the design ratio, and deposit the separation layer on the composite membrane precursor by multi-target magnetron co-sputtering in an inert atmosphere. The pressure of the multi-target magnetron co-sputtering is 1 Pa; the substrate temperature is 380℃; after deposition, transfer it to an annealing furnace and anneal it at 750℃ for 2 hours in a hydrogen atmosphere to obtain the composite membrane material.

[0049] Example 2

[0050] This embodiment provides a composite membrane material and its preparation method, the details of which are as follows:

[0051] The composite membrane material comprises, from bottom to top: a 0.74 mm thick porous Fe-Cr-Al alloy layer, a 16 μm thick Ni / Al2O3 composite material layer, and a 4 μm thick high-entropy alloy separation layer; wherein, the high-entropy alloy separation layer comprises the following elemental composition by mass percentage: Co: 25%, Fe: 18%, Cr: 15%, Al: 5%, V: 4%, Pd: 3%, and the balance Ni.

[0052] The preparation method of the composite membrane material includes the following steps:

[0053] Step 1: The Fe-Cr-Al alloy powder is extruded and drawn to form a hollow blank tube. Under an inert atmosphere, the hollow blank tube is heated to 1150°C at a heating rate of 5°C / min, held at that temperature for 2 hours, and then cooled to room temperature at a cooling rate of 10°C / min to obtain a porous metal support layer.

[0054] Step 2: Mix 0.8 mol / L nickel nitrate solution and AlOOH sol at a mass ratio of 1:2 to obtain a mixed sol; immerse the porous metal support layer in the mixed sol, dry it, and sinter it at 700°C for 1.5 h under a hydrogen atmosphere to obtain the precursor of the composite membrane material;

[0055] Step 3: Weigh the metal raw materials for the high-entropy alloy separation layer according to the design ratio, and deposit the separation layer on the composite membrane precursor by multi-target magnetron co-sputtering in an inert atmosphere. The pressure of the multi-target magnetron co-sputtering is 1.5 Pa, and the substrate temperature is 350℃. After deposition, transfer it to an annealing furnace and anneal it at 720℃ for 2 hours in a hydrogen atmosphere to obtain the composite membrane material.

[0056] Example 3

[0057] This embodiment provides a composite membrane material and its preparation method, the details of which are as follows:

[0058] The composite membrane material comprises, from bottom to top: a 0.69 mm thick porous Fe-Cr-Al alloy layer, a 10 μm thick Ni / Al2O3 composite material layer, and a 5 μm thick high-entropy alloy separation layer; wherein, the high-entropy alloy separation layer comprises the following elemental composition by mass percentage: Co: 18%, Fe: 24%, Cr: 14%, Al: 10%, V: 4%, Pd: 2%, and the balance Ni.

[0059] The preparation method of the composite membrane material includes the following steps:

[0060] Step 1: The Fe-Cr-Al alloy powder is extruded and drawn to form a hollow blank tube. Under an inert atmosphere, the hollow blank tube is heated to 1200°C at a heating rate of 5°C / min and held for 2 hours. Then it is cooled to room temperature at a cooling rate of 10°C / min to form a porous metal support layer.

[0061] Step 2: Mix 0.8 mol / L nickel nitrate solution and AlOOH sol at a mass ratio of 1:1.2 to obtain a mixed sol; immerse the porous metal support layer in the mixed sol, dry it, and sinter it at 780°C for 1 hour under a hydrogen atmosphere to obtain the precursor of the composite membrane material.

[0062] Step 3: Weigh the metal raw materials of the high-entropy alloy separation layer according to the design ratio, and deposit the separation layer on the composite membrane precursor by multi-target magnetron co-sputtering in an inert atmosphere. The pressure of the multi-target magnetron co-sputtering is 1 Pa; the substrate temperature is 380℃; after deposition, transfer it to an annealing furnace and anneal it at 750℃ for 2 hours in a hydrogen atmosphere to obtain the composite membrane material.

[0063] Comparative Example 1

[0064] This comparative example provides a Pd-Ag film; the Pd-Ag film comprises the following metal element composition in weight percentage: Pd: 53.3wt%; Ag: 37.7wt%; Sn: 8.5wt%; In: 0.2wt%; Ru: 0.1wt%; Li: 0.18wt% and unavoidable impurities.

[0065] Comparative Example 2

[0066] This comparative example provides a composite membrane material, which differs from Example 1 in that the high-entropy alloy separation layer is replaced with a nickel-niobium alloy (NiNb). 65 Specifically, it includes the following:

[0067] The composite membrane material comprises, from bottom to top: a 0.78 mm thick porous Fe-Cr-Al alloy layer, a 15 μm thick Ni / Al2O3 composite material layer, and an 8 μm thick high-entropy alloy separation layer; wherein, the high-entropy alloy separation layer comprises the following elemental composition by mass percentage: Co: 22%, Fe: 25%, Cr: 18%, Al: 6%, V: 4%, Pd: 2%, and the balance Ni.

[0068] The preparation method of the composite membrane material includes the following steps:

[0069] Step 1: The Fe-Cr-Al alloy powder is extruded and drawn to form a hollow blank tube. Under an inert atmosphere, the hollow blank tube is heated to 1180°C at a heating rate of 5°C / min and held for 2 hours. Then it is cooled to room temperature at a cooling rate of 10°C / min to form a porous metal support layer.

[0070] Step 2: Mix 0.8 mol / L nickel nitrate solution and AlOOH sol at a mass ratio of 1:1.5 to obtain a mixed sol; immerse the porous metal support layer in the mixed sol, dry it, and sinter it at 700°C for 1.5 h under a hydrogen atmosphere to obtain the precursor of the composite membrane material;

[0071] Step 3: Weigh NiNb according to the design ratio. 65 Metal raw materials are deposited on the composite membrane precursor by multi-target magnetron co-sputtering under an inert atmosphere. The pressure of multi-target magnetron co-sputtering is 1 Pa and the substrate temperature is 380℃. After deposition, the material is transferred to an annealing furnace and annealed at 750℃ for 2 hours under a hydrogen atmosphere to obtain the composite membrane material.

[0072] To further demonstrate the technical effects of the present invention, the membrane materials obtained in Examples 1-3 and Comparative Examples 1-2 were tested as follows:

[0073] Hydrogen permeation flux: The pretreated composite membrane material is fixed in a custom hollow fiber permeation tank. The shell side of the membrane is the feed zone, and the lumen side is the permeation zone. The feed zone is connected to the H2 / He mixed gas supply pipeline, the permeation zone is connected to the N2 purge gas pipeline and the gas chromatograph inlet, and the retention zone (feed zone outlet) is also connected to the gas chromatograph inlet, forming a three-end detection pathway of "feed-permeation-retention".

[0074] Test parameter settings: Temperature range: 400-1000℃, set test temperature points at 100℃ intervals, and hold each temperature point for 30 minutes until the system stabilizes.

[0075] Gas parameters: H2 / He mixed gas (H2 concentrations of 10 vol.%, 50 vol.%, and 90 vol.%) is introduced into the feed side at a total flow rate of 30 mL / min; N2 purge gas is introduced into the permeate side at a flow rate of 60 mL / min; the system pressure is maintained at atmospheric pressure (0.1 MPa) to avoid damage to the membrane structure caused by high pressure.

[0076] Data acquisition and calculation: After the system stabilizes at each temperature point, the gas composition on the permeation side and the retention side is detected by gas chromatography, and the volume fractions of H2 and N2 are recorded. At the same time, the total gas flow rate on the permeation side and the retention side is measured by soap bubble flow meter.

[0077] Mechanical strength: This study uses the three-point bending test method to evaluate the mechanical strength of the composite membrane material. The test is performed using an electronic universal testing machine. The calculation formula is as follows:

[0078] The formula for calculating mechanical strength (bending stress) is as follows:

[0079] σ=8FLD o / π(D o 4 -D i 4 )

[0080] Where: F: force at fracture (N); L: span length (mm); D o Membrane outer diameter (mm); D i : Membrane inner diameter (mm).

[0081] The test results are shown in Table 1.

[0082] Table 1 Test Results

[0083]

[0084] The present invention also performed scanning electron microscopy analysis on the composite membrane material obtained in Example 1, and the results are as follows: Figure 1-3 As shown, from Figure 1As can be seen, the composite membrane material has a sandwich structure from bottom to top, with a porous metal support layer as the substrate, a transition buffer layer above it, and a functional high-entropy alloy separation layer on top. This layered structure is the cornerstone for achieving high-performance hydrogen separation, with clear interfaces between the layers, together forming a complete composite membrane system.

[0085] Figure 2 This is a magnified scanning electron microscope (SEM) image of the cross-section of the composite membrane material, which clearly reveals the microstructure and interface bonding between the layers at high magnification.

[0086] Figure 3 The image shows a SEM image of the outer surface of the composite membrane material (i.e., the surface of the high-entropy alloy separation layer). The image reveals that the surface is uniform and dense overall, without obvious pinholes or cracks. Simultaneously, the surface exhibits a certain nanoscale grain structure, which stems from the multi-principal element characteristics of the high-entropy alloy and the subsequent annealing treatment. This microstructure facilitates the adsorption-dissociation-diffusion process of hydrogen atoms, and its density ensures an extremely high rejection rate for larger molecules such as nitrogen, which is crucial for achieving ultra-high purity hydrogen separation.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite membrane material, characterized in that: The composite membrane material comprises, from bottom to top: a porous metal support layer, a transition buffer layer, and a high-entropy alloy separation layer; wherein, the high-entropy alloy separation layer comprises the following elemental composition by mass percentage: Co: 10%-25%, Fe: 10%-25%, Cr: 5%-20%, Al: 5%-10%, V: 1%-5%, Pd: 1%-3%, and the balance Ni; The porous metal support layer is made of Fe-Cr-Al alloy; The transition buffer layer is made of Ni / Al2O3 composite material.

2. The composite membrane material as described in claim 1, characterized in that: The thickness of the porous metal support layer is 0.5-1 mm; The thickness of the transition buffer layer is 5-20 μm; The thickness of the high-entropy alloy separation layer is 2-10 μm.

3. The composite membrane material as described in claim 2, characterized in that: The porous metal support layer has a porosity of 35%-40% and an average pore size of 0.3-0.5 μm; The surface roughness of the transition buffer layer is ≤200nm.

4. The method for preparing the composite membrane material according to any one of claims 1-3, characterized in that: Specifically, the steps include the following: Step 1: Fe-Cr-Al alloy powder is extruded and drawn to form a hollow blank tube. Under an inert atmosphere, the hollow blank tube is heated to 1150-1200℃, kept at the temperature, and then cooled to form a porous metal support layer. Step 2: Mix the nickel salt solution and the alumina precursor colloid evenly to obtain a mixed sol; immerse the porous metal support layer in the mixed sol, dry it, and sinter it in a reducing atmosphere to obtain the composite membrane material precursor; Step 3: Weigh the metal raw materials of the high-entropy alloy separation layer according to the design ratio, and deposit the separation layer on the composite membrane material precursor by multi-target magnetron co-sputtering in an inert atmosphere. Anneal the material to obtain the composite membrane material.

5. The method for preparing the composite membrane material as described in claim 4, characterized in that: In step one, the temperature is raised to 1150-1200℃ using a programmed temperature rise method, with a heating rate of 3-5℃ / min; In step one, the heat preservation time is 1-3 hours; In step one, a programmed cooling method is used for cooling, with a cooling rate of 5-10℃ / min.

6. The method for preparing the composite membrane material as described in claim 4, characterized in that: In step two, the concentration of the nickel salt solution is 0.5-1 mol / L; In step two, the alumina precursor colloid is AlOOH sol; In step two, the reducing atmosphere is a hydrogen atmosphere; In step two, the mass ratio of the nickel salt solution to the alumina precursor colloid is 1:1 to 1:

2.

7. The method for preparing the composite membrane material as described in claim 4, characterized in that: In step two, the sintering temperature is 650-800℃; In step two, the sintering time is 0.5-2 hours.

8. The method for preparing the composite membrane material as described in claim 4, characterized in that: In step three, the pressure of the multi-target magnetron co-sputtering is 0.5-1.5 Pa; the substrate temperature is 350-450℃. In step three, the annealing process is carried out in a reducing atmosphere; In step three, the annealing temperature is 700-800℃, and the annealing time is 0.5-3h.

9. The application of the composite membrane material according to any one of claims 1-3 in the field of hydrogen separation.

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