A decoupling electrolysis of seawater hydrogen and ammonia generation integrated system and operation method

Abstract

The application discloses a kind of decoupling electrolytic seawater hydrogen production and ammonia generation integrated system and operating method, belong to electrochemistry technical field, comprising: decoupling seawater hydrogen production module, using redox medium decoupling oxygen evolution reaction, make oxygen evolution reaction not directly with chlorine evolution reaction competition, and realize hydrogen evolution reaction and oxygen evolution reaction in different time, different place Separation, and prevent hydrogen oxygen mutual channeling;Nitrogen extraction and ammonia generation module, extract nitrogen from seawater by air separation or membrane separation, and hydrogen and nitrogen are reacted to generate ammonia under the action of catalyst, this process uses solar energy and / or wind energy resources on sea, form hydrogen production and ammonia generation integrated system.The application uses offshore wind power as energy, hydrogen is produced by electrolyzing seawater, and hydrogen and nitrogen are reacted to generate ammonia, realize the efficient use of clean energy and green chemical production.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and more specifically, to an integrated system and operating method for decoupling seawater electrolysis for hydrogen production and ammonia generation. Background Technology

[0002] Hydrogen, as a clean energy source, suffers from high storage and transportation costs. Combining hydrogen with nitrogen to produce ammonia not only enables efficient hydrogen storage and transportation but also provides a green raw material for the chemical industry. Offshore wind power resources are abundant and stable, representing an important direction for future renewable energy development. However, the intermittency of offshore wind power and the high cost of long-distance transmission limit its direct utilization. Combining offshore wind power with water electrolysis to produce hydrogen can not only solve the problem of wind power consumption but also achieve green hydrogen production.

[0003] Ammonia (NH3) is an important chemical raw material, widely used in fertilizer production, energy storage, and fuel applications. Traditional ammonia synthesis relies on the Haber-Bosch process, which requires high-temperature, high-pressure conditions and uses fossil fuels, resulting in high carbon emissions. Utilizing renewable energy sources to electrolyze water to produce hydrogen, and then combining it with nitrogen to synthesize ammonia, can achieve green ammonia production. However, existing technologies suffer from low utilization rates of offshore wind power, low efficiency in water electrolysis for hydrogen production, and low integration of offshore ammonia synthesis processes. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an integrated system and operation method for producing hydrogen and ammonia by electrolysis of seawater. It utilizes offshore wind power as an energy source, produces hydrogen by electrolysis of seawater, and combines the generated hydrogen with nitrogen to generate ammonia, thereby achieving efficient utilization of clean energy and green chemical production.

[0005] The objective of this invention is achieved through the following solution: An integrated system for decoupled seawater electrolysis for hydrogen production and ammonia generation includes: The decoupled seawater hydrogen production module uses an oxidation-reduction medium to decouple the oxygen evolution reaction, so that the oxygen evolution reaction does not directly compete with the chlorine evolution reaction, and the hydrogen evolution reaction and oxygen evolution reaction are separated at different times and locations, thus avoiding the chlorine evolution reaction in principle and preventing hydrogen and oxygen from mixing. The nitrogen extraction and ammonia generation module extracts nitrogen through air separation or membrane separation, and then reacts the generated hydrogen with the nitrogen in the presence of a catalyst to produce ammonia. This process utilizes offshore solar and / or wind energy resources to form an integrated hydrogen production and ammonia generation system.

[0006] Furthermore, the decoupling of the oxygen evolution reaction using a redox medium prevents the oxygen evolution reaction from directly competing with the chlorine evolution reaction, and separates the hydrogen evolution reaction and the oxygen evolution reaction at different times and locations. This theoretically avoids the chlorine evolution reaction and prevents hydrogen and oxygen from mixing. Specifically, this includes: The overall seawater electrolysis hydrogen production is achieved through three processes: power generation by solar photovoltaic units and / or wind power units, electrolytic hydrogen evolution, and spontaneous reduction oxygen evolution. Among them, a pair of redox media are used as electrolyte charge carriers circulating between the hydrogen evolution electrolysis cell and the separate multiphase reactor. In the hydrogen evolution electrolysis cell, hydrogen evolution reaction occurs at the cathode, and oxidation reaction of the medium occurs at the anode. The resulting oxidized medium, which has lost electrons, spontaneously undergoes reduction reaction under the action of a catalyst in the multiphase reactor, thereby completing the medium regeneration and releasing oxygen. The overall reaction formula is the same as that of water electrolysis.

[0007] Furthermore, the redox medium comprises [Fe(CN)6]. 4- Ni(OH)2, DHBQ or VO2 + .

[0008] Furthermore, the redox medium is [Fe(CN)6]. 4- In the decoupled seawater hydrogen production module, the anode storage tank circulates with the anode area of ​​the electrolyzer via a third pump and a delivery pipe to ensure stable liquid levels and gas pressure; the redox medium is [Fe(CN)6]. 4- Dissolving in alkaline seawater, it undergoes an oxidation reaction in the anode reaction zone of the electrolytic cell to form [Fe(CN)6]. 3- The [Fe(CN)6] is introduced into the multiphase reactor via the first pump. 3- It undergoes spontaneous chemical reduction to [Fe(CN)6] under the action of a catalyst. 4- The oxygen released is then processed by an oxygen dryer and stored in a low-pressure oxygen storage tank; the resulting [Fe(CN)6]... 3- The solution is returned to the anode reaction zone of the electrolytic cell via a second pump and a delivery pipe, thus completing a stable cycle of the redox medium.

[0009] Furthermore, in the cathode region of the decoupled seawater hydrogen production module, a seawater electrolytic hydrogen reaction occurs. The cathode storage tank circulates with the cathode reaction region of the electrolytic cell via a fourth pump and a delivery pipe to ensure stable liquid levels and gas pressure. The generated hydrogen is treated by a hydrogen dryer and then temporarily stored in a low-pressure hydrogen storage tank to maintain stable gas pressure. During this process, an anion exchange membrane is used to separate the anode and cathode. - Ions migrate from the cathode to the anode through the anion exchange membrane, ensuring the overall electroneutrality of the system; the hydrogen evolution reaction and oxygen evolution reaction are separated in time and space through the circulation of the redox medium.

[0010] Furthermore, the extraction of nitrogen from seawater via air separation or membrane separation, and the combination of the generated hydrogen and nitrogen with a catalyst to produce ammonia, specifically includes: Air is compressed by an air compressor, and the compressed air is separated into nitrogen by an air separation distillation column. The separated nitrogen is then compressed by a nitrogen compressor. The resulting compressed gas is mixed with hydrogen from a low-pressure hydrogen storage tank in a liquid nitrogen scrubbing tower to form nitrogen-hydrogen synthesis gas. This gas is then compressed by a synthesis gas compressor, and the resulting nitrogen-hydrogen synthesis gas is used to synthesize ammonia in an ammonia synthesis tower. The resulting ammonia is then compressed by an ammonia compressor and circulated through an ammonia storage device. Finally, the resulting liquid ammonia is stored in an ammonia storage tank.

[0011] An operation method for an integrated system for decoupled seawater electrolysis to produce hydrogen and ammonia includes the following steps: S1, Construct an integrated system for hydrogen production and ammonia generation by seawater electrolysis as described in any of the above items; S2, the integrated system for producing hydrogen and ammonia through seawater electrolysis operates as follows: Generating electricity using renewable energy power generation devices; The electricity is then supplied to the electrolysis reactor to produce hydrogen through the electrolysis of seawater: In the cathode region, seawater is electrolyzed to produce hydrogen gas, which is then dried in a hydrogen dryer and stored in a low-pressure hydrogen storage tank; in the anode region, the redox medium [Fe(CN)6] is used. 4- It is oxidized to [Fe(CN)6]. 3- [Fe(CN)6] 3- It enters a multiphase reactor and is reduced to [Fe(CN)6] under the action of a catalyst. 4- It releases oxygen, which is dried by an oxygen dryer and stored in an oxygen low-pressure storage tank; the hydrogen in the hydrogen low-pressure storage tank is mixed with the nitrogen produced by the ammonia production module to synthesize ammonia; air is compressed using an air compressor; nitrogen is separated from the compressed air using an air separation distillation column; and nitrogen is compressed using a nitrogen compressor. Compressed nitrogen and hydrogen are then mixed in a liquid nitrogen scrubbing tower to form nitrogen-hydrogen syngas; the nitrogen-hydrogen syngas is then compressed using a syngas compressor; the compressed nitrogen-hydrogen syngas is then fed into an ammonia synthesis tower to synthesize ammonia; the ammonia is then compressed using an ammonia compressor and stored in an ammonia storage device.

[0012] Furthermore, both the hydrogen low-pressure storage tank and the oxygen low-pressure storage tank are equipped with pressure sensors and regulating valves for real-time monitoring and regulation of gas pressure.

[0013] Furthermore, the ammonia storage device includes a liquid ammonia storage tank and a gaseous ammonia buffer tank, used to store liquid ammonia and gaseous ammonia respectively, and to maintain stable system pressure.

[0014] Furthermore, both the cathode and anode regions of the electrolytic reactor are equipped with temperature sensors and temperature control devices for real-time monitoring and adjustment of the electrolyte temperature.

[0015] Furthermore, it also includes automated control steps for real-time monitoring and adjustment of the operating status of each module, including the operating parameters of the power supply module, hydrogen production module, and ammonia production module, in order to achieve intelligent management and optimized operation of the system.

[0016] The beneficial effects of this invention include: This invention utilizes offshore wind power as an energy source, produces hydrogen through seawater electrolysis, and combines the hydrogen with nitrogen to generate ammonia, achieving a highly efficient conversion from renewable energy to green chemical products. This integrated system not only solves the grid connection problem for offshore wind power but also promotes the green transformation of the chemical industry through the production and utilization of green hydrogen.

[0017] This invention enables the efficient utilization of offshore renewable energy (solar and wind power) and solves the problem of sustainable energy acquisition and conversion.

[0018] This invention produces hydrogen directly by electrolyzing seawater, avoiding the high energy consumption and space limitations of seawater desalination, and reducing the cost of hydrogen production.

[0019] This invention integrates nitrogen extraction and ammonia synthesis modules, which efficiently convert hydrogen into ammonia, solving the problems of hydrogen storage and transportation, and providing green raw materials for the chemical industry.

[0020] The present invention realizes a complete industrial chain from energy production to chemical product manufacturing, and promotes the green transformation of the marine energy and chemical industry. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the system structure according to an embodiment of the present invention; Figure 2 [Fe(CN)6] 3- Cyclic voltammetry curves after 1000 cycles in 1 M KOH + 0.5 M NaCl; Figure 3 [Fe(CN)6] 3- The redox curve lies between the hydrogen evolution and oxygen evolution half-reactions in the electrolytic hydrogen production process. Figure 4 The original chromatogram of hydrogen gas produced during the decoupled direct electrolysis of seawater; Figure 5The original chromatogram of ammonia gas precipitated during the operation of the integrated system for hydrogen production from seawater electrolysis and ammonia generation. In the diagram, 1-Renewable energy power generation device, 2-Electrolysis reactor, 3-Cathode storage tank, 4-Anode storage tank, 5-Third liquid pump, 6-Fourth liquid pump, 7-First liquid pump, 8-Multiphase reactor, 9-Oxygen dryer, 10-Low-pressure oxygen storage tank, 11-Hydrogen dryer, 12-Low-pressure hydrogen storage tank, 13-Air compressor, 14-Air separation distillation column, 15-Nitrogen compressor, 16-Liquid nitrogen scrubbing tower, 17-Synthesis gas compressor, 18-Ammonia synthesis tower, 19-Ammonia storage device, 20-Ammonia compressor, 22-Anion exchange membrane, 23-Cathode area, 24-Anode area, 25-Catalyst, 26-Second liquid pump. Detailed Implementation

[0023] All features disclosed in all embodiments of this specification, or steps in all methods or processes implied in the disclosure, may be combined and / or extended or replaced in any way, except for mutually exclusive features and / or steps.

[0024] In view of the current situation, the inventors of this application, after further creative thinking, believe that: The integrated development trend of hydrogen, ammonia, and methanol production offers broad application prospects for ammonia production technology. This integrated model is a green energy chemical industry that integrates hydrogen energy, green ammonia, and green alcohol production. It utilizes renewable energy to produce hydrogen, which is then synthesized into ammonia or methanol, forming a complete industrial chain from energy production to chemical product manufacturing. This model not only improves energy efficiency but also achieves zero carbon emissions, promoting green and sustainable economic development.

[0025] Currently, offshore wind power hydrogen production systems mainly consist of offshore wind turbine generators, water electrolysis hydrogen production systems, and hydrogen storage and transportation systems. There are two main schemes for offshore wind power hydrogen production: indirect water electrolysis and direct water electrolysis. Indirect seawater hydrogen production technology involves first desalinating seawater to remove salt and impurities, and then using the desalinated water for hydrogen electrolysis. However, seawater desalination is energy-intensive, increasing the overall cost of hydrogen production. Furthermore, the large land area required for desalination makes it unsuitable for space-constrained scenarios such as offshore wind power. Direct seawater electrolysis hydrogen production technology eliminates the need for seawater desalination; the chloride ions (Cl-) in seawater... — This can lead to anodic corrosion and chlorination reactions, reducing electrolysis efficiency and shortening equipment life; while impurities in seawater (such as Na) can cause this. + Mg 2 + Ca 2+ (e.g., etc.) can clog electrodes, leading to catalyst deactivation and membrane damage. Furthermore, integrated marine hydrogen-ammonia system solutions have not been reported in existing technologies.

[0026] Therefore, the present invention provides an integrated system and operating method for wind power electrolysis of seawater to produce hydrogen and ammonia, aiming to solve the problems of low utilization rate of offshore wind power, low efficiency of water electrolysis for hydrogen production, and low integration of offshore ammonia synthesis in existing technologies, thereby achieving efficient utilization of clean energy and green chemical production. Specifically, the provided integrated system for wind power electrolysis of seawater to produce hydrogen and ammonia includes a decoupled seawater electrolysis hydrogen production module and a nitrogen extraction and ammonia generation module.

[0027] In the decoupled seawater electrolysis hydrogen production module, overall seawater electrolysis hydrogen production is achieved through three main processes: solar photovoltaic power generation, electrolytic hydrogen evolution, and spontaneous reduction oxygen evolution. A pair of redox media are used as electrolyte charge carriers circulating between the hydrogen evolution electrolysis cell and a separate multiphase reactor. In the hydrogen evolution electrolysis cell, hydrogen evolution occurs at the cathode, while oxidation of the media occurs at the anode. The resulting media, having lost electrons, spontaneously undergoes reduction under the action of a catalyst in the multiphase reactor, thereby releasing oxygen. The overall reaction is the electrolysis of water.

[0028] Building upon the decoupled seawater electrolysis hydrogen production module, a nitrogen extraction and ammonia generation module has been further integrated. Nitrogen is extracted from seawater using air separation or membrane separation technology, and the generated hydrogen is combined with the nitrogen in the presence of a catalyst to produce ammonia. This process fully utilizes the abundant solar and wind energy resources at sea, avoiding the dependence on fossil fuels in traditional ammonia synthesis and achieving zero carbon emissions.

[0029] It should be noted that, within the scope of protection defined in the claims of this invention, the following embodiments can be combined and / or extended or replaced in any logical manner from the above specific embodiments, such as the disclosed technical principles, disclosed technical features or implicitly disclosed technical features.

[0030] In an optional embodiment, a more specific implementation is provided: a strategy for integrating seawater separation-mediated ammonia synthesis using renewable energy is offered, and based on this, an integrated system for decoupled seawater electrolysis for hydrogen production and ammonia generation is designed, capable of directly producing hydrogen and ammonia from seawater. The system includes a power module, a hydrogen production module, and an ammonia production module. In the power module, offshore wind power or solar photovoltaic power provides electricity to the overall system. In the hydrogen production module, the oxygen evolution reaction is decoupled using a redox medium based on the redox principle, preventing the oxygen evolution reaction from directly competing with the chlorine evolution reaction. This also separates the hydrogen evolution reaction and the oxygen evolution reaction at different times and locations, theoretically avoiding the chlorine evolution reaction and preventing hydrogen and oxygen crosstalk, thus increasing the safety of the hydrogen production system. In the ammonia production module, ammonia is produced using synthesized hydrogen, forming an integrated hydrogen production and ammonia generation system. This increases system integration, achieves simultaneous ammonia production, and reduces hydrogen storage and transportation costs.

[0031] It should be further explained that one of the core innovations of this embodiment lies in the structural design of the hydrogen production module. Compared to traditional hydrogen production modules that separate the generation of hydrogen and oxygen, this module can produce high-purity hydrogen without the need for hydrogen-oxygen separation. Specifically, in the anode region of the hydrogen production module, the anode storage tank 4 circulates with the anode region 24 of the electrolytic cell via a third pump 5 and a delivery pipe to ensure stable liquid levels and gas pressure. The redox medium is [Fe(CN)6]. 4- Dissolved in alkaline seawater, it undergoes an oxidation reaction in the anode reaction zone 24 of the electrolytic cell to form [Fe(CN)6]. 3- The liquid is pumped into the multiphase reactor 8 via the first pump 7, where [Fe(CN)6] is reacted. 3- It undergoes spontaneous chemical reduction to [Fe(CN)6] under the action of catalyst 25. 4- The oxygen released is then processed by oxygen dryer 9 and stored in low-pressure oxygen storage tank 10; the resulting [Fe(CN)6]... 4- The solution is returned to the anode reaction zone 24 of the electrolytic cell via the second pump 26 and the delivery pipe, thereby completing the stable circulation of the redox medium.

[0032] In the cathode region of the hydrogen production module, a seawater electrolysis hydrogen reaction occurs. The cathode storage tank 3 circulates to the cathode reaction zone 23 of the electrolytic cell via a fourth pump 6 through a delivery pipe to ensure stable liquid levels and gas pressure. The generated hydrogen gas is processed by a hydrogen dryer 11 and then temporarily stored in a low-pressure hydrogen storage tank 12 to maintain stable gas pressure. During this process, an anion exchange membrane 22 is used to separate the anode and cathode. To ensure the overall electroneutrality of the system, OH... - The hydrogen and oxygen evolution reactions migrate from the cathode to the anode through an anion exchange membrane. The hydrogen evolution reaction and oxygen evolution reaction are separated in time and space through the circulation of the redox medium. This system avoids the generation of chlorine-containing substances, eliminates the need for additional chemicals, and offers the advantage of spatial decoupling. It completely solves the H2 / O2 gas mixing problem without requiring additional H2 / O2 separation steps, resulting in a significant cost advantage compared to existing hydrogen production systems.

[0033] like Figure 1As shown, the cathode region 23 undergoes the seawater electrolysis hydrogen reaction and is equipped with a cathode storage tank 3, a fourth liquid pump 6, and a hydrogen dryer 11 for circulating the cathode liquid, stabilizing the liquid volume and gas pressure, and drying the generated hydrogen. The anode region 24 undergoes the oxidation reaction of the redox medium and is equipped with an anode storage tank 4, a third liquid pump 5, a first liquid pump 7, a multiphase reactor 8, an oxygen dryer 9, a second liquid pump 26, and a low-pressure oxygen storage tank 10 for circulating the anolyte, stabilizing the liquid volume and gas pressure, conducting the redox reaction, and drying the generated oxygen. An anion exchange membrane 22 separates the cathode region and the anode region and allows OH- to pass through. - Ions pass through to maintain the system's electroneutrality.

[0034] In addition, this embodiment integrates an ammonia production module on the basis of the hydrogen production module, forming an integrated system for hydrogen production and ammonia generation. Air is compressed by air compressor 13, and the compressed air is separated into nitrogen by air separation distillation column 14. The separated nitrogen is then compressed by nitrogen compressor 15 to obtain N2. 80 The nitrogen gas is mixed with hydrogen from the low-pressure hydrogen storage tank 12 in the liquid nitrogen scrubbing tower to form nitrogen-hydrogen synthesis gas. The synthesis gas is compressed by the synthesis gas compressor 17. The resulting nitrogen-hydrogen synthesis compressed gas is synthesized into ammonia gas through the ammonia synthesis tower 18. The resulting ammonia gas is compressed by the ammonia compressor 20 and circulated through the ammonia storage device 19. Finally, the liquid ammonia is stored in the ammonia storage tank.

[0035] like Figure 1 As shown, the ammonia production module uses hydrogen produced by the electrolytic reactor 2 to synthesize ammonia. It includes an air compressor 13 for compressing air; an air separation distillation column 14 for separating nitrogen from the compressed air; a nitrogen compressor 15 for compressing the separated nitrogen; a liquid nitrogen scrubbing column 16 for mixing the compressed nitrogen with hydrogen from the low-pressure hydrogen storage tank 12 to form nitrogen-hydrogen synthesis gas; a synthesis gas compressor 17 for compressing nitrogen-hydrogen synthesis gas; an ammonia synthesis column 18 for synthesizing ammonia; an ammonia compressor 20 for compressing ammonia; and an ammonia storage device 19 for storing liquid ammonia.

[0036] In the above implementation scheme, the principle and structural design of the decoupled seawater direct electrolysis technology were optimized, and a self-reducing semi-decoupled seawater direct electrolysis technology and system were constructed, utilizing [Fe(CN)6]. 3- / 4- As a redox medium, it enables a self-reducing, semi-decoupled direct seawater electrolysis system. The hydrogen evolution reaction and oxygen evolution reaction are separated in time and space through the circulation of the redox medium, avoiding the generation of chlorine-containing substances, eliminating the need for additional chemicals, and offering the advantage of spatial separation, thus completely solving the H2 / O2 gas mixing problem.

[0037] In the above implementation scheme, based on the decoupled seawater hydrogen production process, the redox medium [Fe(CN)6] is used. 4-Dissolving in alkaline seawater, it undergoes an oxidation reaction in the anodic reaction zone of an electrolytic cell to obtain [Fe(CN)6]. 3- In a multiphase reactor, [Fe(CN)6] 3- It undergoes spontaneous chemical reduction to [Fe(CN)6] under the action of a catalyst. 4- It releases oxygen. The resulting [Fe(CN)6] 4- Returning to the anode reaction zone, this completes the stable cycle of the redox medium. Meanwhile, in the cathode reaction zone of the electrolyzer, the electrolytic hydrogen evolution reaction of seawater occurs. The overall reaction is the electrolysis of water molecules. In this system, the redox medium, after being oxidized in place of the oxygen evolution reaction, spontaneously reduces in the multiphase reactor, allowing for repeated recycling and reducing hydrogen production costs. Figure 2 [Fe(CN)6] 3- Cyclic voltammetry curves obtained after 1000 cycles in 1 M KOH + 0.5 M NaCl.

[0038] In the above implementation scheme, decoupled seawater direct electrolysis technology is integrated with ammonia synthesis technology to construct an integrated hydrogen-ammonia system. Hydrogen generated using the decoupled seawater direct electrolysis technology is directly used for ammonia synthesis, eliminating the need for additional hydrogen purification and compression steps, thus reducing ammonia production costs.

[0039] In the above implementation scheme, the entire system can be integrated into a single unit or designed as a floating island-style small hydrogen production base. This improves the system's flexibility and applicability, meeting the application needs of different scenarios.

[0040] In an optional implementation, based on any of the above embodiments, the electrolyte in the hydrogen electrolysis production zone is alkaline seawater with pH=14 KOH, and the effective redox medium in the anode storage tank and multiphase reactor is [Fe(CN)6]. 3- It has good redox properties, such as Figure 3 As shown, this substance exhibits good cycle life with a decay rate of less than 10% after 5,000 cycles in a potassium hydroxide seawater solution at pH 14, demonstrating good electrochemical reversible reaction stability. Furthermore, CV tests of ferricyanide in three solutions confirm that [Fe(CN)6]... 3- The redox potential of this compound lies between the hydrogen evolution reaction and the oxygen evolution reaction in the three solutions, occurring before both reactions. The basic requirements for a redox medium are solubility in an electrolyte under alkaline conditions and stable redox properties, except for [Fe(CN)6]. 3- In addition, including but not limited to AQDS, ADS, BQDS, MDEA, Tiron, Ni(OH)2, DHBQ, VO2 + Phenol, thiazides, etc. Ammonia chromatography, such as... Figure 5 As shown. Figure 4This is the original chromatogram of hydrogen gas precipitated during the decoupled direct electrolysis of seawater.

[0041] In optional embodiments, based on any of the above embodiments, the anode reaction zone 24 is provided with any one of a carbon felt electrode, a platinum mesh electrode, and a gold mesh electrode, and the cathode reaction zone 23 is provided with any one of a platinum-based catalytic electrode, a nickel foam substrate catalytic electrode, and a molybdenum disulfide catalytic electrode.

[0042] In an optional embodiment, based on any of the above embodiments, the multiphase reactor 8 is provided with a catalyst capable of catalyzing the spontaneous chemical reduction of the redox medium, including but not limited to NiFe / NF, NiMoCo / NF, NiMoFe / NF, NiMo / NF and other catalysts capable of catalyzing the spontaneous chemical reduction of the redox medium.

[0043] In optional embodiments, based on any of the above embodiments, the cathode region 23 and anode region 24 of the electrolysis reactor 2 are equipped with temperature sensors and temperature control devices to monitor and adjust the temperature of the electrolyte in real time, so as to ensure that the electrolysis reaction is carried out within the optimal temperature range and improve the reaction efficiency and product purity.

[0044] In an optional embodiment, based on any of the above embodiments, the cathode region 23 and anode region 24 of the electrolysis reactor 2 are further equipped with pH sensors and pH adjustment devices for real-time monitoring and adjustment of the pH value of the electrolyte to ensure that the electrolysis reaction is carried out under optimal pH conditions, thereby further optimizing the reaction efficiency and product quality.

[0045] In an optional embodiment, based on any of the above embodiments, the multiphase reactor 8 is equipped with a stirring device to promote uniform mixing and reaction of the redox media, thereby improving the reaction rate and efficiency. The stirring device can be a mechanical stirrer, a magnetic stirrer, or other types of stirring equipment.

[0046] In an optional embodiment, based on any of the above-described embodiments, the ammonia synthesis tower 18 is equipped with a highly efficient catalyst to accelerate the synthesis reaction of nitrogen and hydrogen, thereby improving the yield and purity of ammonia. The catalyst can be an iron-based catalyst, a ruthenium-based catalyst, or other highly efficient ammonia synthesis catalyst.

[0047] In an optional implementation, based on any of the above embodiments, the ammonia storage device 19 is equipped with a liquid level sensor and a liquid level regulating device for real-time monitoring and regulating of the liquid ammonia storage volume to ensure stable operation and safe storage of the system.

[0048] In an optional implementation, based on any of the above embodiments, the system is further provided with an automated control system for real-time monitoring and adjustment of the operating status of each module, including the operating parameters of the power supply module, hydrogen production module, and ammonia production module, such as voltage, current, temperature, pressure, pH value, etc., so as to realize intelligent management and optimized operation of the system.

[0049] In optional implementations, based on any of the above embodiments, the system is further equipped with safety protection devices, including gas leak detectors, pressure relief valves, emergency shutdown devices, etc., to ensure the safe operation of the system under abnormal conditions and prevent accidents from occurring.

[0050] In optional implementations, based on any of the above embodiments, this invention is primarily targeted at marine areas, but can also be applied to desert areas with scarce freshwater resources and environments with saline wastewater. Utilizing this invention in the process of offshore hydrogen production and power generation can stably generate electricity using seawater and renewable energy while avoiding explosions caused by hydrogen-oxygen cross-contamination in the enclosed marine environment.

[0051] In optional implementations, based on any of the above embodiments, except for [Fe(CN)6]³ - / 4- Other redox mediators can also be considered, such as [Co(bpy)3]. 2+ Ni(OH)2, DHBQ, VO2 + We will explore more efficient and stable redox media. Hybrid redox media, such as [Fe(CN)6]³, can be used. - With [Co(bpy)3]² + By using a combination of methods, the system can adapt to the corrosion and material consumption that may be caused by complex elements in seawater, thereby improving system performance and stability.

[0052] In optional implementations, based on any of the above embodiments, in addition to air separation and membrane separation technologies, other nitrogen extraction technologies, such as pressure swing adsorption and chemisorption, can also be considered to improve nitrogen extraction efficiency.

[0053] In optional implementations, based on any of the above embodiments, in addition to the traditional Haber process, other ammonia synthesis technologies can be considered, such as electrochemical ammonia synthesis, photocatalytic ammonia synthesis, etc., to reduce reaction temperature and pressure, and reduce energy consumption and carbon emissions.

[0054] In summary, the present invention has the following technical advantages: This invention proposes an integrated system and operation method for producing hydrogen and ammonia through seawater electrolysis powered by wind energy. It utilizes offshore wind and solar photovoltaic units to provide clean energy, avoiding dependence on traditional fossil fuels and achieving zero carbon emissions.

[0055] In this invention, the seawater decoupling hydrogen production module uses a redox medium (such as [Fe(CN)6)). 3- The oxidation-substitution electrochemical oxygen evolution reaction eliminates the need for large-scale seawater desalination plants, allowing hydrogen production directly from seawater resources and avoiding the consumption of freshwater.

[0056] The use of redox media in this invention cleverly avoids impurity ions (such as Cl) in seawater. - Na + Mg 2+ The interference of (etc.) on the electrolysis reaction has improved hydrogen production efficiency and extended the service life of the equipment.

[0057] This invention utilizes the recycling of redox media to separate the generation of hydrogen and oxygen on both temporal and spatial scales, eliminating the risk of hydrogen-oxygen crosstalk and reducing the cost of hydrogen collection and storage. Simultaneously, the generated hydrogen can be directly used for ammonia production without the need for hydrogen-oxygen separation, thus reducing ammonia production costs.

[0058] In this invention, the nitrogen extraction module employs air separation or membrane separation technology to efficiently extract nitrogen from seawater, providing ample raw materials for ammonia synthesis. The modular design allows for seamless integration of nitrogen extraction and hydrogen delivery, improving system integration and operational efficiency.

[0059] In this invention, the ammonia generation module achieves efficient ammonia synthesis (3H2+ N2→ 2NH3) through catalyst optimization and reaction condition control, thereby reducing energy consumption and carbon emissions.

[0060] In this invention, ammonia is used as a hydrogen energy carrier, which solves the problems of hydrogen storage and transportation, while providing green raw materials for the chemical industry and promoting the green transformation of the chemical industry.

[0061] This invention further improves the cost-effectiveness and sustainability of the system through the design of redox media and high-performance redox media, and is suitable for energy conversion systems in limited spaces such as floating islands and offshore platforms.

[0062] In addition to the embodiments described above, those skilled in the art can modify the present invention according to the disclosure of the present invention or in combination with knowledge and technology in related fields to obtain other embodiments. The features of these embodiments can be substituted for or combined with each other. As long as these modifications and variations conform to the spirit and scope of the present invention, they should be included within the protection scope of the claims of the present invention.

Claims

1. An integrated system for decoupled seawater electrolysis to produce hydrogen and ammonia, characterized in that, include: The decoupled seawater hydrogen production module uses an oxidation-reduction medium to decouple the oxygen evolution reaction, so that the oxygen evolution reaction does not directly compete with the chlorine evolution reaction, and the hydrogen evolution reaction and oxygen evolution reaction are separated at different times and locations, thus avoiding the chlorine evolution reaction in principle and preventing hydrogen and oxygen from mixing. The nitrogen extraction and ammonia generation module extracts nitrogen through air separation or membrane separation, and then reacts the generated hydrogen with the nitrogen in the presence of a catalyst to produce ammonia. This process utilizes offshore solar and / or wind energy resources to form an integrated hydrogen production and ammonia generation system.

2. The integrated system for decoupled seawater electrolysis to produce hydrogen and ammonia as described in claim 1, characterized in that, The method of decoupling the oxygen evolution reaction using a redox medium prevents the oxygen evolution reaction from directly competing with the chlorine evolution reaction, and separates the hydrogen evolution reaction and the oxygen evolution reaction at different times and locations. This theoretically avoids the chlorine evolution reaction and prevents hydrogen and oxygen from mixing. Specifically, this includes: The overall seawater electrolysis hydrogen production is achieved through three processes: power generation by solar photovoltaic units and / or wind power units, electrolytic hydrogen evolution, and spontaneous reduction oxygen evolution. Among them, a pair of redox media are used as electrolyte charge carriers circulating between the hydrogen evolution electrolysis cell and the separate multiphase reactor. In the hydrogen evolution electrolysis cell, hydrogen evolution reaction occurs at the cathode, and oxidation reaction of the medium occurs at the anode. The resulting oxidized medium, which has lost electrons, spontaneously undergoes reduction reaction under the action of a catalyst in the multiphase reactor, thereby completing the medium regeneration and releasing oxygen. The overall reaction formula is the same as that of water electrolysis.

3. The integrated system for decoupled seawater electrolysis to produce hydrogen and ammonia as described in claim 1, characterized in that, The redox mediator includes [Fe(CN)6] 4- , Ni(OH)2, DHBQ, or VO2 + .

4. The integrated system for decoupled seawater electrolysis to produce hydrogen and ammonia as described in claim 3, characterized in that, The redox medium is [Fe(CN)6]. 4- At that time, in the anode area of ​​the decoupled seawater hydrogen production module, the anode storage tank (4) circulates with the anode area (24) of the electrolyzer via a third pump (5) through a delivery pipe to ensure the stability of liquid storage and gas pressure; redox medium [Fe(CN)6] 4- Dissolved in alkaline seawater, it undergoes an oxidation reaction in the anode reaction zone (24) of the electrolytic cell to form [Fe(CN)6]. 3- The [Fe(CN)6] is introduced into the multiphase reactor (8) via the first pump (7). 3- It undergoes spontaneous chemical reduction to [Fe(CN)6] under the action of catalyst (25) 4- The oxygen released is then processed by an oxygen dryer (9) and stored in a low-pressure oxygen storage tank (10); the resulting [Fe(CN)6]... 3- The solution is returned to the anode reaction zone (24) of the electrolytic cell via the second pump (26) and the delivery pipe, thereby completing the stable circulation of the redox medium.

5. The integrated system for decoupled seawater electrolysis to produce hydrogen and ammonia as described in claim 3, characterized in that, In the cathode region of the decoupled seawater hydrogen production module, a seawater electrolytic hydrogen reaction occurs. The cathode storage tank (3) circulates with the cathode reaction zone (23) of the electrolytic cell via a fourth pump (6) through a delivery pipe to ensure stable liquid storage and gas pressure. The generated hydrogen is processed by a hydrogen dryer (11) and then temporarily stored in a low-pressure hydrogen storage tank (12) to ensure stable gas pressure. During this process, an anion exchange membrane (22) is used to separate the anode and cathode. - Ions migrate from the cathode to the anode through the anion exchange membrane (22), ensuring the overall electroneutrality of the system; the hydrogen evolution reaction and oxygen evolution reaction are separated in time and space through the circulation of the redox medium.

6. The integrated system for decoupled seawater electrolysis to produce hydrogen and ammonia according to claim 1, characterized in that, The extraction of nitrogen from seawater via air separation or membrane separation, followed by the combination of the generated hydrogen and nitrogen with a catalyst to produce ammonia, specifically includes: Air is compressed by an air compressor (13), and nitrogen is separated by an air separation distillation column (14). The separated nitrogen is compressed by a nitrogen compressor (15). The resulting compressed gas is mixed with hydrogen from a low-pressure hydrogen storage tank (12) in a liquid nitrogen scrubbing tower to form nitrogen-hydrogen synthesis gas. The synthesis gas is compressed by a synthesis gas compressor (17), and the resulting nitrogen-hydrogen synthesis compressed gas is synthesized into ammonia by an ammonia synthesis column (18). The resulting ammonia is compressed by an ammonia compressor (20) and circulated through an ammonia storage device (19). Finally, the resulting liquid ammonia is stored in an ammonia storage tank.

7. A method for operating an integrated system for decoupled seawater electrolysis to produce hydrogen and ammonia, characterized in that, Includes the following steps: S1, Construct the integrated system for hydrogen production and ammonia generation by seawater electrolysis as described in any one of claims 1 to 5; S2, the integrated system for producing hydrogen and ammonia through seawater electrolysis operates as follows: Electricity is generated using renewable energy power generation devices (1); The electrical energy is then supplied to the electrolysis reactor (2) to electrolyze seawater to produce hydrogen: in the cathode region (23), seawater electrolyzes hydrogen to produce hydrogen gas, which is then dried by the hydrogen dryer (11) and stored in the low-pressure hydrogen storage tank (12); in the anode region (24), the redox medium [Fe(CN)6] is used. 4- It is oxidized to [Fe(CN)6]. 3- [Fe(CN)6] 3- It enters the multiphase reactor (8) and is reduced to [Fe(CN)6] under the action of catalyst (25). 4- And release oxygen, which is dried by oxygen dryer (9) and stored in oxygen low-pressure storage tank (10); mix hydrogen in hydrogen low-pressure storage tank (12) with nitrogen generated by ammonia production module to synthesize ammonia; use air compressor (13) to compress air; Nitrogen gas is separated from compressed air using an air separation distillation column (14); nitrogen gas is compressed using a nitrogen compressor (15); Compressed nitrogen and hydrogen are then mixed in a liquid nitrogen scrubbing tower (16) to form nitrogen-hydrogen synthesis gas; the nitrogen-hydrogen synthesis gas is compressed using a synthesis gas compressor (17); the compressed nitrogen-hydrogen synthesis gas is fed into an ammonia synthesis tower (18) to synthesize ammonia; the ammonia is compressed using an ammonia compressor (20) and stored in an ammonia storage device (19).

8. The operation method of the integrated system for decoupled seawater electrolysis hydrogen production and ammonia generation according to claim 7, characterized in that, Both the hydrogen low-pressure storage tank (12) and the oxygen low-pressure storage tank (10) are equipped with pressure sensors and regulating valves for real-time monitoring and regulation of gas pressure.

9. The operation method of the integrated system for decoupled seawater electrolysis hydrogen production and ammonia generation according to claim 7, characterized in that, The ammonia storage device (19) includes a liquid ammonia storage tank and a gaseous ammonia buffer tank, which are used to store liquid ammonia and gaseous ammonia respectively and maintain stable system pressure.

10. The operation method of the integrated system for decoupled seawater electrolysis hydrogen production and ammonia generation according to claim 7, characterized in that, Temperature sensors and temperature control devices are provided in both the cathode area (23) and anode area (24) of the electrolysis reactor (2) to monitor and control the temperature of the electrolyte in real time.

11. The operation method of the integrated system for decoupled seawater electrolysis hydrogen production and ammonia generation according to claim 7, characterized in that, It also includes automated control steps for real-time monitoring and adjustment of the operating status of each module, including the operating parameters of the power module, hydrogen production module, and ammonia production module, to achieve intelligent management and optimized operation of the system.

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