Iron-based purification and hydrogen storage integrated material, and preparation method and application thereof

Abstract

The present application relates to a kind of iron-based purification hydrogen storage integrated material and its preparation method and application, the material is with nano iron oxide and nano alumina as matrix, load active metal, wherein nano alumina supports nano iron oxide, the molar ratio of Fe, Al and active metal element is 1: (0.5~1.5): (0.1~0.5), active metal includes Ni or Co.By impregnation synthesis nano alumina supported nano iron oxide catalyst, for the purification and storage of CO and CH4 containing crude hydrogen, with more than 100% hydrogen recovery rate.Compared with prior art, the present application breaks through the limit of traditional crude hydrogen purification and storage, and the developed material and related method have more than 100% hydrogen permeability and greater than 99% hydrogen purity.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen purification and storage, and relates to a method for preparing and using an integrated material for the purification and storage of iron-based crude hydrogen. Background Technology

[0002] Hydrogen energy, as a highly efficient and zero-carbon secondary energy source, is a key vehicle for promoting the green transformation of the energy structure. Currently, global annual hydrogen production exceeds 95 million tons, with China producing over 33 million tons annually. However, more than 95% of this still comes from the reforming of fossil fuels. Meanwhile, the global steel, chemical, and other industries produce approximately 9.9 million tons of hydrogen annually as a byproduct, with China accounting for about 4.6 million tons. Efficient utilization of this industrial byproduct hydrogen would provide a valuable, low-cost hydrogen source for the development of the hydrogen energy industry.

[0003] However, whether produced from fossil fuels or as an industrial byproduct, the resulting hydrogen is crude hydrogen containing various impurities. Industrial hydrogen production and byproduct processes typically involve large amounts of impurities, including CH4, CO2, and CO. Different gas sources, such as refinery dry gas, coke oven gas, and chlor-alkali tail gas, exhibit significant differences in the types and amounts of impurity components. For example, coke oven gas contains approximately 55%–60% H2 by volume, 23%–27% CH4 by volume, and 6%–8% CO by volume. The presence of these impurities, especially components like CO that strongly poison catalytically active sites, severely restricts the direct utilization of crude hydrogen in downstream high-purity hydrogen applications such as fuel cells. Therefore, purification treatment of industrial crude hydrogen and byproduct hydrogen is essential.

[0004] In the field of hydrogen purification, pressure swing adsorption (PSA), membrane separation, cryogenic separation, and metal hydride purification are currently the most commonly used industrial technologies. Among them, PSA technology dominates due to its mature process and wide applicability; using composite gradient adsorbents, hydrogen purity can be increased to over 99.99%. Membrane separation technology, especially separation methods based on palladium-based dense metal membranes, can achieve hydrogen purity up to 99%, but it faces limitations such as high material costs and hydrogen embrittlement risks. In recent years, metal-organic framework (MOF) materials have shown promising application prospects in deep deoxygenation and selective adsorption separation of hydrogen due to their high specific surface area and tunable pore structure. However, these traditional purification technologies generally suffer from long process flows, high energy consumption, and large equipment investment, and the multi-step operation limits hydrogen recovery rates—even under optimized conditions, the hydrogen recovery rate of PSA is typically only about 85%.

[0005] In the field of hydrogen storage, high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, and solid-state hydrogen storage are currently the main hydrogen storage technologies. Compressed hydrogen can achieve a hydrogen storage density of 4-5 wt% at 700 bar pressure, but it faces problems such as high compression energy consumption and large storage tank volume. Although liquid hydrogen storage can achieve a high volumetric density, the liquefaction process is extremely energy-intensive, with an efficiency of only about 30%, and there is also the problem of evaporation loss. Solid-state hydrogen storage materials such as metal hydrides have the advantages of high volumetric hydrogen storage density and inherent safety, and are considered to be a hydrogen storage approach with great development potential. The global hydrogen storage materials market was valued at US$4.2 billion in 2024 and is expected to grow to US$12.1 billion by 2032 at a CAGR of 14.2%, showing strong growth momentum.

[0006] As can be seen from the above situation, the purification and storage of crude hydrogen are currently two separate and independent process steps. Crude hydrogen must first undergo multiple purification steps to remove impurities and obtain high-purity hydrogen gas, which is then stored through compression, liquefaction, or solid-state adsorption. This segmented process of "separation first, storage later" has several limitations: on the one hand, the equipment for purification and storage is independent, resulting in a long process chain, large footprint, and high overall energy consumption per unit of hydrogen processed; on the other hand, the purified hydrogen gas needs to undergo frequent compression and loading / unloading operations during storage and transportation, which not only increases energy loss and equipment investment but also introduces additional safety risks. Existing research indicates an urgent need to develop integrated, process-integrated systems to achieve the production and storage of high-purity hydrogen gas in a more efficient manner.

[0007] To address the aforementioned bottlenecks, in recent years, scholars both domestically and internationally have begun exploring integrated approaches that couple hydrogen separation and storage functions into a single material or process system. For example, a research team from Peking University and Fudan University recently reported a patent (CN116281851B) disclosing an integrated crude hydrogen separation and storage technology based on a γ-butyrolactone / 1,4-butanediol catalytic cycle. Using an impurity-resistant reverse-phase Al2O3 / Cu catalyst, this technology maintains hydrogenation performance comparable to a pure hydrogen atmosphere even under CO concentrations exceeding 50%, achieving one-step separation and chemical storage of H2 from crude hydrogen. This research demonstrates the feasibility of integrating separation and storage functions; however, its material system, using liquid organic matter as a carrier, still faces challenges in terms of hydrogen storage density, cycle stability, and engineering scale-up. Furthermore, existing patents involving integrated hydrogen energy systems mostly focus on the coupling design of process flows (such as connecting reforming hydrogen production with solid-state hydrogen storage tanks in series), and have not yet truly achieved the synergistic integration of separation and hydrogen storage functions at the same material level.

[0008] In summary, developing dual-functional integrated materials that combine crude hydrogen purification and storage capabilities to achieve in-situ separation and efficient storage of hydrogen is an important technological direction for breaking through the bottleneck of the disconnect between purification and storage in the current hydrogen energy industry chain and improving the efficiency of by-product hydrogen resource utilization. Summary of the Invention

[0009] The purpose of this invention is to solve at least one of the above problems by providing an integrated technology for the purification and storage of hydrogen using an iron-based oxygen carrier, thereby achieving the technical effect of improving gasification efficiency while maintaining high hydrogen recovery rate and concentration.

[0010] The objective of this invention can be achieved through the following technical solution: an integrated material for the purification and storage of crude hydrogen based on iron, wherein the material is based on nano-iron oxide and nano-alumina, and loaded with active metals, wherein nano-alumina supports nano-iron oxide, and the molar ratio of Fe, Al and active metal elements is 1:(0.5~1.5):(0.1~0.5), and the active metals include Ni or Co.

[0011] Furthermore, the nano-iron oxide is α-Fe2O3 particles with a particle size of 20-50 nm, and the nano-alumina is γ-Al2O3 particles with a particle size of 20-50 nm.

[0012] This invention also provides a method for preparing an integrated iron-based hydrogen purification and storage material. This material utilizes a nano-alumina-supported nano-iron oxide catalyst synthesized through impregnation, which is used for the purification and storage of crude hydrogen containing CO and CH4, achieving a hydrogen recovery rate exceeding 100%. Specifically, the method includes the following steps: mixing iron oxide particles and alumina particles, adding an active metal salt, adding water, mixing and stirring to react, drying the resulting product until all moisture is evaporated, and then calcining it in air to obtain the final product.

[0013] Furthermore, the active metal salts include Ni(NO3)2·6H2O and Co(NO3)2·6H2O.

[0014] Furthermore, the mixing and stirring reaction is carried out at room temperature for 4-8 hours.

[0015] Furthermore, the drying process is carried out at 100~110℃ for 60~84 hours.

[0016] Furthermore, the calcination is carried out by raising the temperature from room temperature to 250~350℃ at a heating rate of 5℃ / min, holding at that temperature for 20~40min, and then raising the temperature to 800~900℃ at a heating rate of 5℃ / min, holding at that temperature for 1~3h.

[0017] The present invention also provides an application of an iron-based integrated material for hydrogen purification and storage, wherein the integrated material is used for hydrogen purification and storage.

[0018] Furthermore, the integrated material undergoes hydrogen reduction and steam pretreatment before use. The hydrogen reduction process involves heating from room temperature to 650-750°C at a rate of 8-12°C / min, holding at that temperature for 1-3 hours, with a hydrogen flow rate of 25-35 mL / min. Subsequently, nitrogen is introduced for purging, and the temperature is raised to 800-900°C at a rate of 8-12°C / min for steam pretreatment. During steam pretreatment, the nitrogen flow rate is 80-120 mL / min, and the deionized water flow rate is 0.2-0.4 mL / min. The process is monitored in real time until the outlet hydrogen concentration drops below 0.5%, at which point the deionized water is shut off.

[0019] Furthermore, the sources of crude hydrogen for hydrogen purification and storage include methane steam reforming, coal gasification, and hydrogen produced as a byproduct of smelting. The temperature for crude hydrogen purification and storage is 800~900 ℃, the flow rate of crude hydrogen is 40~60 ml / min, and nitrogen carrier gas is used at 40~60 ml / min. After the reaction time is 10~30 min, the crude hydrogen inlet is closed. After the hydrogen content stabilizes to below 0.5%, the hydrogen release process is carried out. During the hydrogen release process, the nitrogen flow rate is 80~120 mL / min, and the deionized water flow rate is 0.2~0.4 mL / min. Real-time monitoring is maintained until the outlet hydrogen concentration drops below 0.5%, at which point the deionized water flow is shut off.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention innovatively employs an iron-based oxygen carrier as an integrated material for hydrogen purification and storage. It utilizes the reaction between the iron-based oxygen carrier and hydrogen, as well as the enhanced oxidizing properties of an active agent, to achieve unified oxidation of both hydrogen and impurities. Hydrogen release is then completed via water vapor. This process achieves a hydrogen recovery rate exceeding 100% and a hydrogen concentration greater than 99%. It provides a new technological pathway for the integrated purification and storage of hydrogen energy. Detailed Implementation

[0021] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0022] To address the current technical problems of lengthy purification, storage, and transportation processes, including low purification efficiency, low safety, and high cost, this invention develops an integrated metal oxide technology for hydrogen purification, storage, and transportation, achieving high hydrogen recovery rates (>100%) and hydrogen concentrations (>99%). First, a certain mass of alumina powder, iron oxide powder, and active component powder are mixed. Then, deionized water is added and mixed thoroughly before being transferred to a drying oven for drying. After complete drying, the mixture is ground and calcined in air. Subsequently, hydrogen reduction and steam pretreatment are performed. Crude hydrogen is then introduced for purification and storage. During the hydrogen release step, steam is introduced to release hydrogen, and this purification, storage, and hydrogen release steps are repeated multiple times.

[0023] Preferably, the iron oxide used is in the form of nanoparticles or powder with a particle size of 20-50 nm; the alumina used is also in the form of nanoparticles or powder with a particle size of 20-50 nm. In several embodiments, preferably, the size of both the iron oxide and alumina is less than 30 nm. Furthermore, the nano-iron oxide used in this invention is commercially available α-Fe₂O₃ particles, and the nano-alumina used is commercially available γ-Al₂O₃ particles.

[0024] In several embodiments, the atomic ratio of Fe, Al, and the active metal element is 1:1:0.2.

[0025] In several embodiments, the stirring time is 5 to 8 hours; preferably, the stirring time is 6 hours.

[0026] In several embodiments, the calcination temperature is 500~900℃; preferably, the calcination temperature is 850℃.

[0027] In several embodiments, the hydrogen reduction temperature is 500~800°C; preferably, the calcination temperature is 700°C.

[0028] In several embodiments, the hydrogen reduction time is 1-5 hours; preferably, the hydrogen reduction time is 2 hours.

[0029] In several embodiments, the hydrogen purification and storage temperature is 800-900 °C; preferably, the hydrogen purification and storage temperature is 850 °C.

[0030] In several embodiments, the purification and hydrogen storage time is 10-30 min; preferably, the purification and hydrogen storage time is 20 min.

[0031] In several embodiments, the hydrogen release time is 10-30 min; preferably, the hydrogen release time is 20 min.

[0032] In several embodiments, the hydrogen release temperature is 800-900 °C; preferably, the hydrogen release temperature is 850 °C.

[0033] In several embodiments, the crude hydrogen is selected as coke oven gas with a flow rate of 50 ml / min and a composition of 60% H2, 8% CO, 4% CO2, 23% CH4, and 5% N2.

[0034] In several embodiments, the volumetric yield of hydrogen is calculated using equation (1): (1) in, This represents the real-time concentration of hydrogen, in vol%. Total flow rate during hydrogen release phase, mL / min -1 .

[0035] Example 1 An integrated metal oxide technology for hydrogen purification, storage, and transportation achieves high hydrogen recovery rates (>100%) and hydrogen concentrations (>99%), specifically including the following steps: S1. Mix iron oxide particles and aluminum oxide particles: Iron oxide particles and aluminum oxide particles, both with a particle size of 20-30 nm, were mixed at a molar ratio of Fe2O3 to Al2O3 of 1:1. In this example, 15.00 g of iron oxide powder and 9.58 g of aluminum oxide powder were weighed out.

[0036] S2. Mix Ni(NO3)2·6H2O, add pure water and stir: Ni(NO3)2·6H2O was added to the mixed powder obtained in step S1, so that the molar ratio of Ni to Fe was 0.2:1 (i.e., the molar ratio of Ni to Fe was 0.2). In this embodiment, 10.93 g of Ni(NO3)2·6H2O was weighed and added to the oxide mixture. Then 100 ml of deionized water was added to form a slurry, and the mixture was continuously stirred with a magnetic stirrer for 6 hours to ensure that the components were fully and evenly dispersed.

[0037] S3, Drying: The slurry obtained in step S2 was placed in a constant temperature drying oven and dried at 105°C for 72 hours until the moisture was completely evaporated, thus obtaining a solid precursor.

[0038] S4, Air calcination: The dried solid precursor from step S3 was transferred to a muffle furnace and calcined in air. The programmed heating rate was 5 °C / min, with two holding stages: first, holding at 300 °C for 30 minutes, then continuing to heat to 850 °C and holding for 2 hours. After calcination, the mixture was allowed to cool naturally to room temperature to obtain the iron-aluminum composite metal oxide (Ni-Fe2O3 / Al2O3).

[0039] S5. Hydrogen reduction and steam pretreatment: Each time, 8.19 g of the sample after calcination in step S4 was taken and loaded into a fixed-bed reactor. First, hydrogen reduction was performed: hydrogen was introduced at a flow rate of 30 mL / min, and the temperature was increased to 700℃ at a rate of 10℃ / min, and held at 700℃ for 2 hours to reduce Fe₂O₃ to Fe. After reduction, the reactor was switched to nitrogen purging to remove residual hydrogen.

[0040] Subsequent steam pretreatment (activation) was performed: under a nitrogen atmosphere (flow rate 100 mL / min), deionized water (flow rate 0.3 mL / min) was introduced to raise the reactor temperature to 850℃. The hydrogen concentration in the outlet gas was monitored in real time using a hydrogen concentration detector. When the outlet hydrogen concentration dropped below 0.5%, the deionized water supply was shut off. This step allows stable water-gas shift reaction active sites to form on the material surface.

[0041] S6. Pass crude hydrogen through for purification and storage: The reactor temperature was maintained at 850℃. The crude hydrogen source was coke oven gas (composition: 60% H2, 8% CO, 4% CO2, 23% CH4, 5% N2). Crude hydrogen was introduced into the reactor at a flow rate of 50 mL / min, with nitrogen at a flow rate of 50 mL / min as the carrier gas. The reaction time was 20 minutes. During this process, CO impurities in the crude hydrogen reacted with active oxygen in the material, while hydrogen was stored in the oxygen vacancies of the material's crystal lattice. The outlet hydrogen concentration was monitored in real time; when the outlet hydrogen concentration stabilized below 0.5%, the purification and storage steps were considered complete.

[0042] S7. Passing in water vapor to release hydrogen: After completing step S6, stop the flow of crude hydrogen and carrier nitrogen. Switch to a nitrogen atmosphere (flow rate 100 mL / min) while simultaneously introducing deionized water (flow rate 0.3 mL / min), maintaining the reaction temperature at 850℃. Water vapor reacts with the reduced metal (Fe) in the material, releasing high-purity hydrogen. Monitor the outlet hydrogen concentration in real time; when the outlet hydrogen concentration drops below 0.5%, shut off the deionized water supply, ending the hydrogen release process.

[0043] S8. Repeated purification and release: Steps S6 and S7 were repeated for a total of 3 cycles. During each cycle, the hydrogen absorption capacity of the purification and storage steps and the hydrogen production of the release step remained stable without significant decline, indicating that the material exhibits good cycle stability.

[0044] Table 1. Hydrogen production in the Ni-Fe2O3 / Al2O3 three-stage purification hydrogen storage-release cycle In the table above, the first, second, and third cycles refer to the amount of hydrogen released during the three hydrogen purification, storage, and release cycles, respectively. "Hydrogen in crude hydrogen" refers to the hydrogen content in the crude hydrogen being introduced. The third-cycle concentration refers to the concentration of hydrogen produced in the third cycle, measured by GC. As can be seen from the table, the amount of hydrogen released exceeds the amount of hydrogen introduced into the crude hydrogen, and the hydrogen concentration released in the third cycle is as high as 99.27%.

[0045] Example 2 Unlike Example 1, this example uses Co-doped Fe2O3 / Al2O3 as the raw material for purification and hydrogen storage.

[0046] S1. Mix iron oxide particles and aluminum oxide particles: Iron oxide particles and aluminum oxide particles, both with a particle size of 20-30 nm, were mixed at a molar ratio of Fe2O3 to Al2O3 of 1:1. In this example, 15.00 g of iron oxide powder and 9.58 g of aluminum oxide powder were weighed out.

[0047] S2. Mix Co(NO3)2·6H2O, add pure water and stir: Co(NO3)2·6H2O was added to the mixed powder obtained in step S1 to make the molar ratio of Ni to Fe 0.2:1 (i.e., the molar ratio of Ni to Fe is 0.2). In this embodiment, 10.94 g of Ni(NO3)2·6H2O was weighed and added to the oxide mixture. Then 100 ml of deionized water was added to form a slurry, and the mixture was continuously stirred with a magnetic stirrer for 6 hours to ensure that the components were fully and evenly dispersed.

[0048] S3, Drying: The slurry obtained in step S2 was placed in a constant temperature drying oven and dried at 105°C for 72 hours until the moisture was completely evaporated, thus obtaining a solid precursor.

[0049] S4, Air calcination: The dried solid precursor from step S3 was transferred to a muffle furnace and calcined in air. The programmed heating rate was 5 °C / min, with two holding stages: first, holding at 300 °C for 30 minutes, then continuing to heat to 850 °C and holding for 2 hours. After calcination, the mixture was allowed to cool naturally to room temperature to obtain an iron-aluminum composite metal oxide (Co-Fe2O3 / Al2O3).

[0050] S5. Hydrogen reduction and steam pretreatment: Each time, 8.19 g of the sample after calcination in step S4 was taken and loaded into a fixed-bed reactor. First, hydrogen reduction was performed: hydrogen was introduced at a flow rate of 30 mL / min, and the temperature was increased to 700℃ at a rate of 10℃ / min, and held at 700℃ for 2 hours to reduce Fe₂O₃ to Fe. After reduction, the reactor was switched to nitrogen purging to remove residual hydrogen.

[0051] Subsequent steam pretreatment (activation) was performed: under a nitrogen atmosphere (flow rate 100 mL / min), deionized water (flow rate 0.3 mL / min) was introduced to raise the reactor temperature to 850℃. The hydrogen concentration in the outlet gas was monitored in real time using a hydrogen concentration detector. When the outlet hydrogen concentration dropped below 0.5%, the deionized water supply was shut off. This step allows stable water-gas shift reaction active sites to form on the material surface.

[0052] S6. Pass crude hydrogen through for purification and storage: The reactor temperature was maintained at 850℃. The crude hydrogen source was coke oven gas (composition: 60% H2, 8% CO, 4% CO2, 23% CH4, 5% N2). Crude hydrogen was introduced into the reactor at a flow rate of 50 mL / min, with nitrogen at a flow rate of 50 mL / min as the carrier gas. The reaction time was 20 minutes. During this process, CO impurities in the crude hydrogen reacted with active oxygen in the material, while hydrogen was stored in the oxygen vacancies of the material's crystal lattice. The outlet hydrogen concentration was monitored in real time; when the outlet hydrogen concentration stabilized below 0.5%, the purification and storage steps were considered complete.

[0053] S7. Passing in water vapor to release hydrogen: After completing step S6, stop the flow of crude hydrogen and carrier nitrogen. Switch to a nitrogen atmosphere (flow rate 100 mL / min) while simultaneously introducing deionized water (flow rate 0.3 mL / min), maintaining the reaction temperature at 850℃. Water vapor reacts with the reduced metal (Fe) in the material, releasing high-purity hydrogen. Monitor the outlet hydrogen concentration in real time; when the outlet hydrogen concentration drops below 0.5%, shut off the deionized water supply, ending the hydrogen release process.

[0054] S8. Repeated purification and release: Steps S6 and S7 were repeated for a total of 3 cycles. During each cycle, the hydrogen absorption capacity of the purification and storage steps and the hydrogen production of the release step remained stable without significant decline, indicating that the material exhibits good cycle stability.

[0055] Table 2 Hydrogen production in the Co-Fe2O3 / Al2O3 three-stage purification, storage, and release cycle As can be seen from the table above, the amount of hydrogen released in the first three cycles of the Co-doped iron-based oxygen carrier still exceeds the amount of hydrogen introduced into the crude hydrogen.

[0056] Comparative Example 1 This comparative example uses Fe2O3 / Al2O3 for integrated hydrogen purification, storage, and transportation technology, specifically including the following steps: S1. Mix iron oxide particles and aluminum oxide particles: Take iron oxide particles and aluminum oxide particles, both with a particle size of 20-30 nm, and mix them according to a molar ratio of Fe2O3 to Al2O3 of 1:1. In this comparative example, 15.00 g of iron oxide powder and 9.58 g of aluminum oxide powder were weighed out respectively.

[0057] S2. Add pure water and stir: Add 100 ml of deionized water to the mixed powder obtained in step S1 to form a slurry, and stir continuously for 6 hours using a magnetic stirrer to ensure that the components are fully dispersed and uniform.

[0058] S3, Drying: The slurry obtained in step S2 was placed in a constant temperature drying oven and dried at 105°C for 72 hours until the moisture was completely evaporated, thus obtaining a solid precursor.

[0059] S4, Air calcination: The dried solid precursor from step S3 was transferred to a muffle furnace and calcined in air. The programmed heating rate was 5 °C / min, with two holding stages: first, holding at 300 °C for 30 minutes, then continuing to heat to 850 °C and holding for 2 hours. After calcination, the mixture was allowed to cool naturally to room temperature to obtain the iron-aluminum composite metal oxide (Fe2O3 / Al2O3).

[0060] S5. Hydrogen reduction and steam pretreatment: Each time, 8.19 g of the sample after calcination in step S4 was taken and loaded into a fixed-bed reactor. First, hydrogen reduction was performed: hydrogen was introduced at a flow rate of 30 mL / min, and the temperature was increased to 700℃ at a rate of 10℃ / min, and held at 700℃ for 2 hours to reduce Fe₂O₃ to Fe. After reduction, the reactor was switched to nitrogen purging to remove residual hydrogen.

[0061] Subsequent steam pretreatment (activation) was performed: under a nitrogen atmosphere (flow rate 100 mL / min), deionized water (flow rate 0.3 mL / min) was introduced to raise the reactor temperature to 850℃. The hydrogen concentration in the outlet gas was monitored in real time using a hydrogen concentration detector. When the outlet hydrogen concentration dropped below 0.5%, the deionized water supply was shut off. This step allows stable water-gas shift reaction active sites to form on the material surface.

[0062] S6. Pass crude hydrogen through for purification and storage: The reactor temperature was maintained at 850℃. The crude hydrogen source was coke oven gas (composition: 60% H2, 8% CO, 4% CO2, 23% CH4, 5% N2). Crude hydrogen was introduced into the reactor at a flow rate of 50 mL / min, with nitrogen at a flow rate of 50 mL / min as the carrier gas. The reaction time was 20 minutes. During this process, CO impurities in the crude hydrogen reacted with active oxygen in the material, while hydrogen was stored in the oxygen vacancies of the material's crystal lattice. The outlet hydrogen concentration was monitored in real time; when the outlet hydrogen concentration stabilized below 0.5%, the purification and storage steps were considered complete.

[0063] S7. Passing in water vapor to release hydrogen: After completing step S6, stop the flow of crude hydrogen and carrier nitrogen. Switch to a nitrogen atmosphere (flow rate 100 mL / min) while simultaneously introducing deionized water (flow rate 0.3 mL / min), maintaining the reaction temperature at 850℃. Water vapor reacts with the reduced metal (Fe) in the material, releasing high-purity hydrogen. Monitor the outlet hydrogen concentration in real time; when the outlet hydrogen concentration drops below 0.5%, shut off the deionized water supply, ending the hydrogen release process.

[0064] S8. Repeated purification and release: Steps S6 and S7 were repeated for a total of 3 cycles. During each cycle, the hydrogen absorption capacity of the purification and storage steps and the hydrogen production of the release step remained stable without significant decline, indicating that the material exhibits good cycle stability.

[0065] Table 3. Hydrogen production from three Fe2O3 / Al2O3 purification, storage, and release cycles. As can be seen from the table above, the amount of hydrogen released in the comparative example is much lower than the amount of hydrogen in the crude hydrogen introduced.

[0066] This invention demonstrates that the iron-based hydrogen purification and storage integrated material used in this invention achieves in-situ separation and efficient storage of hydrogen, breaking through the limitations of traditional crude hydrogen purification and storage. The developed material and related methods have a hydrogen permeability of over 100% and a hydrogen purity of over 99%.

[0067] The foregoing has shown and described the basic process, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An integrated material for the purification and storage of crude iron-based hydrogen, characterized in that, The material is based on nano-iron oxide and nano-alumina, with active metals loaded on it. The nano-alumina supports the nano-iron oxide, and the molar ratio of Fe, Al and active metal elements is 1:(0.5~1.5):(0.1~0.5). The active metals include Ni or Co.

2. The iron-based integrated hydrogen purification and storage material according to claim 1, characterized in that, The nano-iron oxide is α-Fe2O3 particles with a particle size of 20-50 nm, and the nano-alumina is γ-Al2O3 particles with a particle size of 20-50 nm.

3. A method for preparing an iron-based integrated hydrogen purification and storage material as described in claim 1 or 2, characterized in that, The process includes the following steps: mixing iron oxide particles and aluminum oxide particles, adding active metal salts, adding water, mixing and stirring to react, drying the resulting product until the water is completely evaporated, and then calcining it in air to obtain the product.

4. The preparation method of an iron-based integrated hydrogen purification and storage material according to claim 3, characterized in that, The active metal salts include Ni(NO3)2·6H2O and Co(NO3)2·6H2O.

5. The preparation method of an iron-based integrated hydrogen purification and storage material according to claim 3, characterized in that, The mixing and stirring reaction is carried out at room temperature for 4-8 hours.

6. The preparation method of an iron-based integrated hydrogen purification and storage material according to claim 3, characterized in that, The drying process involves drying at 100-110℃ for 60-84 hours.

7. The preparation method of an iron-based integrated hydrogen purification and storage material according to claim 3, characterized in that, The calcination process involves raising the temperature from room temperature to 250-350°C at a rate of 5°C / min, holding at that temperature for 20-40 minutes, and then raising the temperature to 800-900°C at a rate of 5°C / min, holding at that temperature for 1-3 hours.

8. The application of an iron-based integrated hydrogen purification and storage material as described in any one of claims 1 to 3, characterized in that, The integrated material is used for hydrogen purification and storage.

9. The application of the iron-based integrated hydrogen purification and storage material according to claim 8, characterized in that, Before use, the integrated material undergoes hydrogen reduction and water vapor pretreatment. The hydrogen reduction process involves heating from room temperature to 650-750°C at a rate of 8-12°C / min, holding at that temperature for 1-3 hours, with a hydrogen flow rate of 25-35 mL / min. Subsequently, nitrogen is introduced for purging, and the temperature is raised to 800-900°C at a rate of 8-12°C / min for water vapor pretreatment. During the steam pretreatment process, the nitrogen flow rate is 80~120 mL / min, and the deionized water flow rate is 0.2~0.4 mL / min. The deionized water flow rate is monitored in real time until the outlet hydrogen concentration drops below 0.5% and then the deionized water flow is turned off.

10. The application of the iron-based integrated hydrogen purification and storage material according to claim 8, characterized in that, The sources of crude hydrogen for hydrogen purification and storage include methane steam reforming, coal gasification, and hydrogen by-products from smelting. The temperature for crude hydrogen purification and storage is 800~900 ℃, the crude hydrogen flow rate is 40~60 ml / min, and nitrogen carrier gas is used at 40~60 ml / min. After the reaction time is 10~30 min, the crude hydrogen inlet is closed. After the hydrogen content stabilizes to below 0.5%, the hydrogen release process is carried out. During the hydrogen release process, the nitrogen flow rate is 80~120 mL / min, and the deionized water flow rate is 0.2~0.4 mL / min. Real-time monitoring is maintained until the outlet hydrogen concentration drops below 0.5%, at which point the deionized water flow is shut off.

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