Aluminum recycling method for metallic aluminum energy storage and hydrogen production

Abstract

Disclosed herein is an aluminum recycling method for metallic aluminum energy storage and hydrogen production, comprising: electrolyzing aluminum oxide to obtain molten metallic aluminum; processing the molten metallic aluminum to obtain an aluminum-based hydrogen production material; under the action of a catalyst, chemically reacting the aluminum-based hydrogen production material with water to obtain hydrogen gas and an aluminum oxide hydrate slurry; subjecting the aluminum oxide hydrate slurry to solid-liquid separation to obtain an aluminum oxide hydrate and an aqueous solution containing the catalyst; calcining the aluminum oxide hydrate to obtain aluminum oxide; and recycling the aluminum oxide to the step of electrolyzing the aluminum oxide, and recycling the aqueous solution containing the catalyst to the step of chemically reacting the aluminum-based hydrogen production material with water, thereby forming a closed-loop cycle.

Description

An aluminum cycle method for energy storage and hydrogen production using metallic aluminum.

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese patent application No. 202411798932.5, filed on December 09, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of new energy application technology, and in particular to an aluminum recycling method for energy storage and hydrogen production using metallic aluminum. Background Technology

[0004] In 2020, based on the inherent requirements of promoting sustainable development and its responsibility to build a community with a shared future for mankind, China announced its goals and vision for carbon peaking and carbon neutrality. Developing new energy technologies such as wind power and photovoltaic power generation, as well as efficient energy storage technologies, is one of the main technological pathways to achieving these goals. Currently, new energy technology routes based on aluminum energy storage mainly include aluminum-air batteries and aluminum-based hydrogen production materials-water hydrogen production. Although aluminum-air batteries have significant advantages such as high specific energy density and environmental friendliness, they also have drawbacks such as low specific power density, which affects their large-scale commercial application. Aluminum-based hydrogen production materials-water hydrogen production technology, on the other hand, fully utilizes the high energy density of aluminum and the unique advantages of hydrogen fuel cells, such as high energy conversion efficiency, strong power adjustability, environmental friendliness, and short refueling time, showing promising development prospects.

[0005] However, current research on aluminum-based hydrogen production materials and water-based hydrogen production technology has only proposed the idea of ​​recycling aluminum elements after hydrogen production from aluminum-based hydrogen production materials and water-based hydrogen production, and has not yet formed a practically feasible technical route. Summary of the Invention

[0006] An aluminum recycling method for energy storage and hydrogen production using one or more embodiments of this disclosure is provided to address the technical problem of how to achieve a complete recycling method for energy storage and hydrogen production using aluminum.

[0007] In a first aspect, according to some embodiments of this disclosure, an aluminum recycling method for energy storage and hydrogen production using metallic aluminum includes: electrolyzing alumina to obtain liquid aluminum; processing the liquid aluminum to obtain an aluminum-based hydrogen production material with a large specific surface area; chemically reacting the aluminum-based hydrogen production material with water under the action of a nitrogen-containing strongly alkaline organic catalyst to obtain hydrogen and an alumina hydrate slurry; performing solid-liquid separation on the alumina hydrate slurry to obtain alumina hydrate and an aqueous solution containing the catalyst; calcining the alumina hydrate to obtain highly active metallurgical-grade alumina; and recycling the highly active metallurgical-grade alumina in the step of electrolyzing alumina and recycling the aqueous solution containing the catalyst in the step of chemically reacting the aluminum-grade hydrogen production material with water to form a closed-loop cycle. Attached Figure Description

[0008] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0009] To more clearly illustrate the technical solutions in the embodiments or related technologies of this disclosure, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0010] Figure 1 shows a schematic flow diagram of an aluminum recycling method for energy storage and hydrogen production in metallic aluminum according to some embodiments of the present disclosure.

[0011] Figure 2 shows a simplified process diagram of an aluminum recycling method for energy storage and hydrogen production in metallic aluminum according to some embodiments of the present disclosure. Embodiments of the present invention

[0012] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0013] Various embodiments of this disclosure may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this disclosure; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0014] In this disclosure, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the orientation shown in the accompanying drawings. Furthermore, in the description of this disclosure, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships may exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. In the proportional relationships discussed in this article, the parameters described by the proportion should be understood as the first term of the proportion in the order of description, while the proportion figures should be understood as the second term. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substances A, B, and C should correspond one-to-one with the proportion figures in the proportion in the order of description, i.e., the mass of substance A : the mass of substance B : the mass of substance C = 1 : 2 : 3.

[0015] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this disclosure are available on the market or can be prepared by existing methods.

[0016] Firstly, this document discloses an aluminum recycling method for energy storage and hydrogen production using metallic aluminum. Figure 1 shows a schematic flow diagram of the aluminum recycling method for energy storage and hydrogen production using metallic aluminum according to some embodiments of this disclosure; referring to Figure 1, the aluminum recycling method for energy storage and hydrogen production using metallic aluminum according to some embodiments of this disclosure includes:

[0017] S1. Electrolyze aluminum oxide to obtain molten aluminum.

[0018] S2. Process the molten aluminum to obtain an aluminum-based hydrogen production material with a large specific surface area;

[0019] S3. Under the action of a nitrogen-containing strong alkaline organic catalyst, aluminum-based hydrogen production materials are chemically reacted with water to obtain hydrogen and alumina hydrate slurry.

[0020] S4. The alumina hydrate slurry is subjected to solid-liquid separation to obtain alumina hydrate and an aqueous solution containing the catalyst.

[0021] S5. The alumina hydrate is calcined to obtain highly active metallurgical grade alumina.

[0022] S6. The highly active metallurgical grade alumina is recycled in the step of electrolyzing alumina, and the aqueous solution containing the catalyst is recycled in the step of chemical reaction between the aluminum-based hydrogen production material and water, forming a closed loop.

[0023] As described above, according to some embodiments of the aluminum recycling method for energy storage and hydrogen production using metallic aluminum, alumina is electrolyzed to obtain liquid aluminum. During electrolysis, electrical energy is converted into chemical energy and stored in the liquid aluminum, thus achieving energy storage of metallic aluminum (liquid). This liquid aluminum is then processed to obtain an aluminum-based hydrogen production material with a large specific surface area, increasing the contact area between the aluminum-based hydrogen production material and water. An aqueous solution of a nitrogen-containing strongly alkaline organic compound can rapidly dissolve and remove the oxide film on the surface of the aluminum-based hydrogen production material, accelerating the chemical reaction rate between the aluminum-based hydrogen production material and water, thereby improving the efficiency of hydrogen production. Simultaneously, during the chemical reaction between the aluminum-based hydrogen production material and water, the chemical energy stored in the aluminum-based hydrogen production material (metallic aluminum) is transferred and stored in the produced hydrogen. The chemical energy stored in the hydrogen is more readily applicable, for example, through hydrogen fuel cells. Furthermore, the nitrogen-containing strongly alkaline organic catalyst has high solubility in water and good dispersion of the alumina hydrate produced by hydrolysis, thus more effectively exerting its catalytic effect. Alumina hydrate obtained by solid-liquid separation of an alumina hydrate slurry is calcined to obtain highly active metallurgical-grade alumina. This highly active metallurgical-grade alumina is recycled into the alumina electrolysis process. Utilizing the high dissolution rate of this highly active metallurgical-grade alumina in the molten electrolyte, the current efficiency of the alumina electrolysis process can be effectively improved. By recycling the highly active metallurgical-grade alumina into the aforementioned alumina electrolysis process, and by recycling the catalyst-containing aqueous solution into the chemical reaction between the aforementioned aluminum-based hydrogen production material and water, a closed-loop cycle of aluminum energy storage and hydrogen production is formed, thus realizing a complete cycle of aluminum energy storage and hydrogen production.

[0024] Furthermore, the aluminum recycling method for energy storage and hydrogen production using aluminum metal, according to some embodiments of this disclosure, achieves efficient utilization of aluminum, zero solid waste emissions, and near-zero carbon emissions in the closed-loop cycle of aluminum metal energy storage and hydrogen production.

[0025] In some embodiments, in step S1, the electrical energy for electrolysis is derived from green electricity.

[0026] In some embodiments, in step S1, the inert anode for electrolysis includes any one of the following: SnO2 ceramic anode and Cu-Ni-Fe metal anode.

[0027] In some embodiments of this disclosure, alumina can first be electrolyzed to obtain molten aluminum, thereby converting electrical energy into chemical energy stored in the aluminum, achieving the purpose of storing electrical energy using molten aluminum. During the electrolysis process, alumina dissolves in a molten salt electrolyte such as cryolite (Na3AlF6 or K3AlF6). Under the action of direct current, alumina is reduced to molten aluminum at the cathode, and electrical energy is converted into chemical energy stored in the molten aluminum. The electrical energy generated by electrolysis can be derived from green electricity, thereby reducing greenhouse gas emissions such as carbon dioxide at the source and making the aluminum electrolysis production process more environmentally friendly. Green electricity can be one of wind power, solar power, or photovoltaic power. By sending green electricity (green power) such as wind power to an aluminum electrolysis plant using inert anode technology, the alumina electrolysis process using inert anode technology fundamentally solves the problems of perfluorocarbon (PFC) emissions and anode consumption CO2 emissions. The inert anode for this electrolysis can be a SnO2 ceramic anode or a Cu-Ni-Fe metal anode. In the alumina electrolysis production process using this inert anode, a small amount of metal elements such as Sn and Fe in the inert anode can enter the molten aluminum and form an aluminum alloy with the molten aluminum. This is beneficial to improve the reactivity of aluminum-based hydrogen production materials and accelerate the subsequent aluminum-based hydrogen production material-water hydrogen production reaction rate.

[0028] For example, S1 includes: in an aluminum electrolysis plant using wind power and applying SnO2 or Cu-Ni-Fe ceramic anode technology, alumina can first be dissolved in cryolite molten salt, and then molten aluminum is obtained by electrolysis.

[0029] In some embodiments, the purpose of processing the molten aluminum in step S2 is to increase the specific surface area of ​​the aluminum-based hydrogen production material. This allows the aluminum-based hydrogen production material to have a larger specific surface area compared to aluminum ingots in related technologies, thereby enhancing its surface activity. Specific surface area refers to the surface area per unit mass or unit volume of material, and it is an important parameter for measuring the surface activity of a material. Increasing the specific surface area aims to improve the material's reaction rate, enhance its adsorption capacity, and improve its electrochemical performance, thereby improving the material's performance in specific applications. Processing methods for increasing specific surface area include physical methods, chemical methods, and biological methods. Compared to unprocessed materials, materials with increased specific surface area after processing have significant advantages in reaction rate and adsorption efficiency.

[0030] In some embodiments, the aluminum-based hydrogen production material may be in the form of either aluminum granules or aluminum shavings.

[0031] In some embodiments, 90% of the aluminum particles have a particle size D90 of 30 μm to 1000 μm; and / or, the maximum thickness of the aluminum shavings is ≤1 mm.

[0032] In some embodiments of this disclosure, in step S2, the processing method for the molten aluminum can be atomization or machining. The resulting aluminum-based hydrogen production material can be in the form of aluminum particles and / or aluminum shavings. 90% of the aluminum particles have a particle size D90 of 30 μm to 1000 μm; the maximum thickness of the aluminum shavings can be ≤1 mm, thereby ensuring that the aluminum-based hydrogen production material has a large specific surface area, thus accelerating the chemical reaction rate between the aluminum-based hydrogen production material and water, and ensuring that the aluminum-based hydrogen production material can react completely with water.

[0033] For example, when 90% of the aluminum particles have a particle size D90 of 30 μm to 1000 μm, the specific surface area of ​​the aluminum-based hydrogen production material existing in the form of aluminum particles is approximately 11.11 cm². 2 / g~370.37 cm 2 / g.

[0034] For example, the particle size D90 of 90% of the aluminum particles can be 30μm, 40μm, 50μm, 60μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, etc.

[0035] In some embodiments of this disclosure, the nitrogen-containing strongly basic organic catalyst in step S3 includes at least one of the following: diethylenetriamine, triethylenetetramine, and metformin hydroxide.

[0036] In some embodiments of this disclosure, an aqueous solution of a nitrogen-containing strongly alkaline organic catalyst can remove the oxide film on the surface of the aluminum-based hydrogen production material, thereby accelerating the chemical reaction between the aluminum-based hydrogen production material and water, and thus improving the efficiency of hydrogen production. The nitrogen-containing strongly alkaline organic catalyst has high solubility in water, which allows it to be uniformly dispersed in water, increasing the dispersibility and fluidity of the generated alumina hydrate slurry, thereby more effectively exerting its catalytic effect. Furthermore, under the action of the nitrogen-containing strongly alkaline organic catalyst, and with relatively mild chemical reaction process parameters, efficient hydrogen production can be achieved, and the obtained alumina hydrate does not contain sodium.

[0037] In some embodiments of this disclosure, the nitrogen-containing strongly basic organic catalyst may be one or more of diethylenetriamine, triethylenetetramine, and metformin hydroxide.

[0038] In some embodiments, the process parameters of the chemical reaction include: a reaction temperature of 20°C to 95°C and a reaction time of 60 min to 720 min.

[0039] In some embodiments of this disclosure, the reaction temperature of the above chemical reaction can be 20°C to 95°C, thereby controlling the reaction rate of the chemical reaction and controlling the appropriate hydrogen production reaction time according to the reaction temperature. The reaction time can be 60 min to 720 min, which can fully improve the utilization rate of aluminum-based hydrogen production materials.

[0040] For example, the reaction temperature of the chemical reaction can be 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, 95℃, etc.; the reaction time of the chemical reaction can be 60min, 70min, 80min, 90min, 100min, 200min, 300min, 400min, 500min, 600min, 720min, etc.

[0041] In some embodiments, the mass ratio of the catalyst to the water is 1:(4 to 40).

[0042] In some embodiments of this disclosure, the mass ratio of catalyst to water can be 1:(4-40), thereby ensuring a moderate concentration of catalyst in the chemical reaction system. This allows for rapid activation of the reaction in its initial stages, increases the contact opportunities between catalyst molecules and the aluminum-based hydrogen production material and water, and provides sufficient active sites to accelerate the electron transfer process between the aluminum-based hydrogen production material and water. This, in turn, speeds up the chemical reaction between the aluminum-based hydrogen production material and water.

[0043] For example, the mass ratio of the catalyst to water can be 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, etc.

[0044] In some embodiments, the mass ratio of the aluminum-based hydrogen production material to the water is 1:(4-60).

[0045] In some embodiments of this disclosure, the mass ratio of aluminum-based hydrogen production material to water can be 1:(4-60), which can make the concentration of aluminum-based hydrogen production material in the chemical reaction system moderate, ensuring the hydrogen production reaction rate while the alumina hydrate slurry after the chemical reaction has good fluidity.

[0046] For example, the mass ratio of the aluminum-based hydrogen production material to water can be 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, etc.

[0047] In some embodiments of this disclosure, in step S5, the calcination process parameters include: calcination temperature of 750℃~1020℃ and calcination time of 3s~20min.

[0048] In some embodiments of this disclosure, the alumina hydrate slurry undergoes solid-liquid separation to obtain alumina hydrate and an aqueous solution containing the catalyst. Generally, the alumina hydrate obtained from the above-mentioned aluminum-based hydrogen production material reacting with water requires washing and drying. Calcining the alumina hydrate yields highly active metallurgical-grade alumina. The calcination process parameters include: a calcination temperature of 750℃ to 1020℃ and a calcination time of 3 seconds to 20 minutes, ensuring the acquisition of qualified highly active metallurgical-grade alumina, which exhibits excellent solubility in molten electrolytes.

[0049] For example, the roasting temperature can be 750℃, 800℃, 850℃, 900℃, 950℃, 1000℃, 1020℃, etc.; the roasting time can be 3s, 4s, 5s, 6s, 7s, 8s, 20s, 30s, 1min, 2min, 3min, 4min, 5min, 6min, 7min, 8min, 9min, 10min, 12min, 14min, 15min, 17min, 19min, 20min, etc.

[0050] In some embodiments of this disclosure, in step S6, the highly active metallurgical-grade alumina has a large specific surface area and high reactivity, which can improve the efficiency of the electrolysis process. This highly active metallurgical-grade alumina is recycled for electrolysis and exhibits a high dissolution rate in the molten electrolyte, thus improving the current efficiency of the electrolysis process. The dissolution rate of this highly active metallurgical-grade alumina in cryolite or potassium-containing cryolite molten salt can be increased by more than 50% compared to typical industrial alumina, and the current efficiency of the electrolysis process can be increased by more than 2% (the dissolution rate of typical industrial alumina is 100s–200s, the current efficiency of ordinary electrolysis is 92%–95%, and the current efficiency is less than 90% when using inert anode technology). This highly active metallurgical-grade alumina does not contain sodium, which can reduce the consumption of fluoride salts in the alumina electrolysis process. The highly active metallurgical-grade alumina can be recycled for the electrolytic preparation of metallic aluminum liquid, and the aforementioned aqueous solution containing the catalyst can be recycled for the chemical reaction of the aforementioned aluminum-based hydrogen production material with water to produce hydrogen. Therefore, this method achieves efficient utilization of aluminum, zero solid waste discharge, and near-zero carbon emissions. Furthermore, the system for realizing this aluminum recycling method for energy storage and hydrogen production can include a hydrogen production system, an aluminum material recycling plant, green energy generation facilities such as wind power, and an aluminum electrolysis plant using inert anode technology.

[0051] The aluminum recycling method for energy storage and hydrogen production using metallic aluminum according to some embodiments of this disclosure has the following advantages:

[0052] 1. Electrolysis of alumina yields molten aluminum (energy storage stage)

[0053] Principle and Significance: In the electrolytic production of molten aluminum, electrical energy is converted into chemical energy and stored in the molten aluminum, giving it the potential to release energy (for hydrogen production or other applications). From an energy utilization perspective, this energy storage method, combined with green electricity (such as electricity generated from wind power, solar power, and other renewable energy sources), can effectively solve the instability problem in the power generation process of renewable energy sources like wind power, improving the stability and flexibility of energy utilization.

[0054] 2. Processing molten aluminum into aluminum-based hydrogen production materials

[0055] The importance of specific surface area: Processing aluminum-based hydrogen production materials with a large specific surface area means that more aluminum atoms can come into contact with water, thereby increasing the reaction sites and accelerating the reaction rate.

[0056] 3. The role of nitrogen-containing strongly alkaline organic catalysts in hydrogen production reactions

[0057] Catalytic Mechanism: When nitrogen-containing strongly basic organic catalysts participate in the chemical reaction between aluminum-based hydrogen production materials and water, the catalysts exist in the form of an aqueous solution. These catalysts can rapidly dissolve and remove the oxide film on the surface of the aluminum-based hydrogen production materials, thereby accelerating the hydrogen production reaction. Furthermore, the basic groups of the nitrogen-containing strongly basic organic catalysts promote the dissociation of water, generating more active hydroxide ions and accelerating the hydrogen production process.

[0058] Advantages of solubility: The high solubility of nitrogen-containing strong alkaline organic catalysts in water ensures their uniform dispersion, which can improve the dispersibility and fluidity of the generated alumina hydrate slurry, thereby promoting the chemical reaction.

[0059] 5. Calcination of alumina hydrate

[0060] Calcining alumina hydrate yields highly active metallurgical-grade alumina. Because alumina hydrate has higher surface activity than ordinary industrial aluminum hydroxide, calcination produces highly active metallurgical-grade alumina.

[0061] 6. Recycling process

[0062] The recycling of highly active metallurgical grade alumina: When highly active metallurgical grade alumina is recycled for electrolysis, it has a high dissolution rate in the molten electrolyte, which is beneficial to improving electrolysis efficiency. The high activity of highly active metallurgical grade alumina also makes the current efficiency higher during electrolysis, reducing energy loss and energy consumption.

[0063] The circulation of catalyst-containing aqueous solutions: The circulation of catalyst-containing aqueous solutions participates in the chemical reaction between aluminum-based hydrogen production materials and water, which reduces the consumption of nitrogen-containing strong alkaline organic catalysts, lowers costs, and avoids the environmental pollution problems that may be caused by the emission of nitrogen-containing strong alkaline organic catalysts.

[0064] The present disclosure is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the disclosure. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If no corresponding national standard exists, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0065] Example 1

[0066] An aluminum recycling method for energy storage and hydrogen production using metallic aluminum is disclosed. Figure 1 shows a schematic flow diagram of an aluminum recycling method for energy storage and hydrogen production using metallic aluminum according to some embodiments of the present disclosure; Figure 2 shows a simplified schematic flow diagram of an aluminum recycling method for energy storage and hydrogen production using metallic aluminum according to some embodiments of the present disclosure. Referring to Figures 1 and 2, the aluminum recycling method for energy storage and hydrogen production using metallic aluminum includes:

[0067] S1. Electrolyze aluminum oxide to obtain molten aluminum.

[0068] Specifically, in an electrolytic aluminum plant using wind power and SnO2 ceramic anode technology, alumina is first dissolved in cryolite molten salt at 945°C, and then molten aluminum is obtained through electrolysis.

[0069] S2. The molten aluminum is processed to obtain an aluminum-based hydrogen production material with a large specific surface area; wherein, the aluminum-based hydrogen production material is aluminum particles with a D90 of 30μm (90% of the particles have a particle size of less than 30μm);

[0070] S3. Under the action of a nitrogen-containing strong alkaline organic catalyst, aluminum-based hydrogen production materials are chemically reacted with water to obtain hydrogen and alumina hydrate slurry.

[0071] Specifically, aluminum granules, a nitrogen-containing strongly alkaline organic catalyst, and distilled water are added to an aluminum-water hydrogen production system in a specific ratio. The nitrogen-containing strongly alkaline organic catalyst is diethylenetriamine, the mass ratio of the nitrogen-containing strongly alkaline organic catalyst to distilled water is 1:4, the mass ratio of aluminum granules to distilled water is 1:60, the chemical reaction temperature is 95℃, the reaction time is 60 min, and the reaction rate of the aluminum granules is 98.1%.

[0072] S4. The alumina hydrate slurry is subjected to solid-liquid separation to obtain alumina hydrate and an aqueous solution containing the catalyst;

[0073] S5. The alumina hydrate is calcined to obtain highly active metallurgical grade alumina; wherein the calcination temperature is 750℃ and the calcination time is 20min.

[0074] S6. The highly active metallurgical grade alumina is recycled for electrolysis in step S1, and the aqueous solution containing the catalyst is replenished with fresh water and catalyst and then recycled to participate in the chemical reaction in step S3, forming a closed loop.

[0075] Compared with ordinary industrial alumina, the dissolution rate of highly active alumina in cryolite molten salt in Example 1 was increased by 56%, and the current efficiency of the electrolysis process was increased by 2.5%.

[0076] Example 2

[0077] An aluminum recycling method for energy storage and hydrogen production using metallic aluminum, comprising:

[0078] S1. Electrolyze aluminum oxide to obtain molten aluminum.

[0079] Specifically, in an electrolytic aluminum plant using wind power and SnO2 ceramic anode technology, alumina is first dissolved in cryolite molten salt at 960°C, and then molten aluminum is obtained through electrolysis.

[0080] S2. The molten aluminum is processed to obtain an aluminum-based hydrogen production material with a large specific surface area; wherein, the aluminum-based hydrogen production material is aluminum particles with a D90 of 1000μm (90% of the particles have a particle size of less than 1000μm).

[0081] S3. Under the action of a nitrogen-containing strong alkaline organic catalyst, aluminum-based hydrogen production materials are chemically reacted with water to obtain hydrogen and alumina hydrate slurry.

[0082] Specifically, aluminum granules, a nitrogen-containing strongly alkaline organic catalyst, and distilled water are added to an aluminum-water hydrogen production system in a specific ratio. The nitrogen-containing strongly alkaline organic catalyst is triethylenetetramine, the mass ratio of the nitrogen-containing strongly alkaline organic catalyst to distilled water is 1:10, the mass ratio of aluminum granules to distilled water is 1:20, the chemical reaction temperature is 20℃, the reaction time is 720 min, and the reaction rate of the aluminum granules is 99.6%.

[0083] S4. The alumina hydrate slurry is subjected to solid-liquid separation to obtain alumina hydrate and an aqueous solution containing the catalyst;

[0084] S5. The alumina hydrate is calcined to obtain highly active metallurgical grade alumina; wherein the calcination temperature is 1020℃ and the calcination time is 3s.

[0085] S6. The highly active metallurgical grade alumina is recycled for electrolysis in step S1, and the aqueous solution containing the catalyst is replenished with fresh water and catalyst and then recycled to participate in the chemical reaction in step S3, forming a closed loop.

[0086] Compared with ordinary industrial alumina, the dissolution rate of highly active alumina in cryolite molten salt in Example 2 was increased by 70%, and the current efficiency of the electrolysis process was increased by 3.0%.

[0087] Example 3

[0088] An aluminum recycling method for energy storage and hydrogen production using metallic aluminum, comprising:

[0089] S1. Electrolyze aluminum oxide to obtain molten aluminum.

[0090] Specifically, in an electrolytic aluminum plant using wind power and SnO2 ceramic anode technology, alumina is first dissolved in cryolite molten salt at 950°C, and then molten aluminum is obtained through electrolysis.

[0091] S2. The molten aluminum is processed to obtain an aluminum-based hydrogen production material with a large specific surface area; wherein the aluminum-based hydrogen production material is aluminum shavings with a maximum thickness of 1 mm.

[0092] S3. Under the action of a nitrogen-containing strong alkaline organic catalyst, aluminum-based hydrogen production materials are chemically reacted with water to obtain hydrogen and alumina hydrate slurry.

[0093] Specifically, aluminum shavings, a nitrogen-containing strongly alkaline organic catalyst, and distilled water are added to an aluminum-water hydrogen production system in a specific ratio. The nitrogen-containing strongly alkaline organic catalyst is metformin hydroxide, the mass ratio of the nitrogen-containing strongly alkaline organic catalyst to distilled water is 1:4, the mass ratio of aluminum shavings to distilled water is 1:6, the chemical reaction temperature is 65℃, the reaction time is 480 min, and the reaction rate of the aluminum shavings is 99.8%.

[0094] S4. The alumina hydrate slurry is subjected to solid-liquid separation to obtain alumina hydrate and an aqueous solution containing the catalyst;

[0095] S5. The alumina hydrate is calcined to obtain highly active metallurgical grade alumina; wherein the calcination temperature is 1000℃ and the calcination time is 10s.

[0096] S6. The highly active metallurgical grade alumina is recycled for electrolysis in step S1, and the aqueous solution containing the catalyst is replenished with fresh water and catalyst and then recycled to participate in the chemical reaction in step S3, forming a closed loop.

[0097] Compared with ordinary industrial alumina, the dissolution rate of highly active alumina in cryolite molten salt in Example 3 was increased by 51%, and the current efficiency of the electrolysis process was increased by 3.2%.

[0098] Example 4

[0099] An aluminum recycling method for energy storage and hydrogen production using metallic aluminum, comprising:

[0100] S1. Electrolyze aluminum oxide to obtain molten aluminum.

[0101] Specifically, in an electrolytic aluminum plant using wind power and applying Cu-Ni-Fe metal anode technology, alumina is first dissolved in cryolite molten salt at 750°C, and then electrolyzed to obtain molten aluminum.

[0102] S2. The molten aluminum is processed to obtain an aluminum-based hydrogen production material with a large specific surface area; wherein the aluminum-based hydrogen production material is aluminum particles with a D90 of 80μm (90% of the particles have a particle size of less than 80μm);

[0103] S3. Under the action of a nitrogen-containing strong alkaline organic catalyst, aluminum-based hydrogen production materials are chemically reacted with water to obtain hydrogen and alumina hydrate slurry.

[0104] Specifically, aluminum granules, a nitrogen-containing strongly alkaline organic catalyst, and distilled water are added to an aluminum-water hydrogen production system in a specific ratio. The nitrogen-containing strongly alkaline organic catalyst is a mixture of metformin hydroxide, diethylenetriamine, and triethylenetetramine in a mass ratio of 1:1:1. The mass ratio of the nitrogen-containing strongly alkaline organic catalyst to distilled water is 1:10, and the mass ratio of aluminum granules to distilled water is 1:4. The chemical reaction temperature is 55℃, the reaction time is 540 min, and the reaction rate of the aluminum granules is 99.3%.

[0105] S4. The alumina hydrate slurry is subjected to solid-liquid separation to obtain alumina hydrate and an aqueous solution containing the catalyst;

[0106] S5. The alumina hydrate is calcined to obtain highly active metallurgical grade alumina; wherein the calcination temperature is 750℃ and the calcination time is 20min.

[0107] S6. The highly active metallurgical grade alumina is recycled for electrolysis in step S1, and the aqueous solution containing the catalyst is replenished with fresh water and catalyst and then recycled to participate in the chemical reaction in step S3, forming a closed loop.

[0108] Compared with ordinary industrial alumina, the dissolution rate of highly active alumina in cryolite molten salt in Example 4 was increased by 80%, and the current efficiency of the electrolysis process was increased by 4.2%.

[0109] Example 5

[0110] An aluminum recycling method for energy storage and hydrogen production using metallic aluminum, comprising:

[0111] S1. Electrolyze aluminum oxide to obtain molten aluminum.

[0112] Specifically, in an electrolytic aluminum plant using wind power and applying Cu-Ni-Fe metal anode technology, alumina is first dissolved in cryolite molten salt at 740°C, and then electrolyzed to obtain molten aluminum.

[0113] S2. The molten aluminum is processed to obtain an aluminum-based hydrogen production material with a large specific surface area; wherein, the aluminum-based hydrogen production material is aluminum particles with a D90 of 40μm (90% of the particles have a particle size of less than 40μm);

[0114] S3. Under the action of a nitrogen-containing strong alkaline organic catalyst, aluminum-based hydrogen production materials are chemically reacted with water to obtain hydrogen and alumina hydrate slurry.

[0115] Specifically, aluminum granules, a nitrogen-containing strongly alkaline organic catalyst, and distilled water are added to an aluminum-water hydrogen production system in a specific ratio. The nitrogen-containing strongly alkaline organic catalyst is a mixture of diethylenetriamine and triethylenetetramine in a mass ratio of 2:1. The mass ratio of the nitrogen-containing strongly alkaline organic catalyst to distilled water is 1:20, and the mass ratio of aluminum granules to distilled water is 1:20. The chemical reaction temperature is 85℃, the reaction time is 120 min, and the reaction rate of the aluminum granules is 99.6%.

[0116] S4. The alumina hydrate slurry is subjected to solid-liquid separation to obtain alumina hydrate and an aqueous solution containing the catalyst;

[0117] S5. The alumina hydrate is calcined to obtain highly active metallurgical grade alumina; wherein the calcination temperature is 1000℃ and the calcination time is 3s.

[0118] S6. The highly active metallurgical grade alumina is recycled for electrolysis in step S1, and the aqueous solution containing the catalyst is replenished with fresh water and catalyst and then recycled to participate in the chemical reaction in step S3, forming a closed loop.

[0119] Compared with ordinary industrial alumina, the dissolution rate of highly active alumina in cryolite molten salt in Example 5 was increased by 60%, and the current efficiency of the electrolysis process was increased by 5.3%.

[0120] Example 6

[0121] An aluminum recycling method for energy storage and hydrogen production using metallic aluminum, comprising:

[0122] S1. Electrolyze aluminum oxide to obtain molten aluminum.

[0123] Specifically, in an electrolytic aluminum plant using wind power and applying Cu-Ni-Fe metal anode technology, alumina is first dissolved in cryolite molten salt at 760°C, and then electrolyzed to obtain molten aluminum.

[0124] S2. The molten aluminum is processed to obtain an aluminum-based hydrogen production material with a large specific surface area; wherein, the aluminum-based hydrogen production material is aluminum particles with a D90 of 800μm (90% of the particles have a particle size of less than 800μm).

[0125] S3. Under the action of a nitrogen-containing strong alkaline organic catalyst, aluminum-based hydrogen production materials are chemically reacted with water to obtain hydrogen and alumina hydrate slurry.

[0126] Specifically, aluminum granules, a nitrogen-containing strongly alkaline organic catalyst, and distilled water are added to an aluminum-water hydrogen production system in a specific ratio. The nitrogen-containing strongly alkaline organic catalyst is a mixture of metformin hydroxide and triethylenetetramine in a mass ratio of 1:4. The mass ratio of the nitrogen-containing strongly alkaline organic catalyst to distilled water is 1:40, and the mass ratio of aluminum granules to distilled water is 1:12. The chemical reaction temperature is 95℃, the reaction time is 180 min, and the reaction rate of the aluminum granules is 99.3%.

[0127] S4. The alumina hydrate slurry is subjected to solid-liquid separation to obtain alumina hydrate and an aqueous solution containing the catalyst;

[0128] S5. The alumina hydrate is calcined to obtain highly active metallurgical grade alumina; wherein the calcination temperature is 750℃ and the calcination time is 20min.

[0129] S6. The highly active metallurgical grade alumina is recycled for electrolysis in step S1, and the aqueous solution containing the catalyst is replenished with fresh water and catalyst and then recycled to participate in the chemical reaction in step S3, forming a closed loop.

[0130] Compared with ordinary industrial alumina, the dissolution rate of highly active alumina in cryolite molten salt in Example 6 was increased by 75%, and the current efficiency of the electrolysis process was increased by 6.1%.

[0131] One or more technical solutions in the embodiments of this disclosure have at least the following technical effects or advantages:

[0132] (1) According to some embodiments of the present disclosure, the aluminum recycling method for energy storage and hydrogen production of metallic aluminum produces highly active metallurgical grade alumina with a dissolution rate of more than 50% in cryolite or potassium-containing cryolite molten salt compared with typical industrial alumina, and the current efficiency of the electrolysis process is increased by more than 2%.

[0133] (2) According to some embodiments of the present disclosure, the aluminum recycling method for energy storage and hydrogen production of metallic aluminum uses nitrogen-containing strong alkaline organic matter as a catalyst in the aluminum-based hydrogen production material-water hydrogen production process, which has the advantages of fast reaction speed and no sodium element in aluminum oxide hydrate.

[0134] (3) In the aluminum recycling method for energy storage and hydrogen production of aluminum metal according to some embodiments of the present disclosure, during the alumina electrolysis process using SnO2 ceramic anode or Cu-Ni-Fe metal anode as inert anode, a small amount of metal elements such as Sn and Fe in the inert anode can enter the aluminum metal liquid to form aluminum alloy, which is more conducive to improving the reactivity of hydrogen production materials and accelerating the reaction rate of aluminum-based hydrogen production materials-water hydrogen production.

[0135] (4) In the aluminum recycling method for energy storage and hydrogen production of metallic aluminum according to some embodiments of the present disclosure, the raw material used for alumina electrolysis is highly active metallurgical grade alumina, which does not contain sodium, thereby reducing the consumption of fluoride salts in the production process of metallic aluminum.

[0136] (5) According to some embodiments of the present disclosure, the aluminum recycling method for energy storage and hydrogen production of metallic aluminum uses inert anode technology in the alumina electrolysis process, which fundamentally solves the problem of perfluorocarbon (PFC) emissions.

[0137] (6) An aluminum recycling method for energy storage and hydrogen production of metallic aluminum according to some embodiments of the present disclosure, wherein alumina electrolysis produces metallic aluminum liquid using highly active metallurgical grade alumina as raw material, and highly active metallurgical grade alumina has the advantages of fast dissolution rate and high current efficiency.

[0138] (7) The aluminum recycling method for energy storage and hydrogen production using metallic aluminum according to some embodiments of this disclosure achieves efficient utilization of aluminum, zero solid waste discharge, and near-zero carbon emissions. The above descriptions are merely specific embodiments of this disclosure, enabling those skilled in the art to understand or implement this disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An aluminum recycling method for energy storage and hydrogen production in metallic aluminum, comprising: Alumina is electrolyzed to obtain molten aluminum. The molten aluminum is processed to obtain an aluminum-based hydrogen production material with a large specific surface area; Under the action of a nitrogen-containing strongly alkaline organic catalyst, the aluminum-based hydrogen production material is chemically reacted with water to obtain hydrogen gas and an alumina hydrate slurry. The alumina hydrate slurry was subjected to solid-liquid separation to obtain alumina hydrate and an aqueous solution containing the catalyst. The alumina hydrate was calcined to obtain highly active metallurgical grade alumina; as well as, The highly active metallurgical-grade alumina is recycled in the step of electrolyzing the alumina, and the aqueous solution containing the catalyst is recycled in the step of chemically reacting the aluminum-based hydrogen production material with water, forming a closed-loop cycle.

2. The method according to claim 1, wherein, The nitrogen-containing strongly basic organic catalyst includes at least one of the following: diethylenetriamine, triethylenetetramine, and metformin hydroxide.

3. The method according to claim 1, wherein, The roasting process parameters include: roasting temperature of 750℃~1020℃ and roasting time of 3s~20min.

4. The method according to claim 1, wherein, The process parameters for the chemical reaction include: a reaction temperature of 20℃ to 95℃ and a reaction time of 60 min to 720 min.

5. The method according to claim 1, wherein, The mass ratio of the catalyst to the water is 1:(4-40).

6. The method according to claim 1, wherein, The mass ratio of the aluminum-based hydrogen production material to the water is 1:(4-60).

7. The method according to claim 1, wherein, The aluminum-based hydrogen production material can be in any of the following forms: aluminum granules and aluminum shavings.

8. The method according to claim 7, wherein, 90% of the aluminum particles have a particle size D90 of 30μm to 1000μm; and / or, The maximum thickness of the aluminum shavings is ≤1mm.

9. The method according to claim 1, wherein, The electrical energy used in the electrolysis is derived from green electricity.

10. The method according to claim 1 or 9, wherein, The inert anode for electrolysis includes any one of the following: SnO2 ceramic anode and Cu-Ni-Fe metal anode.

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