Electrolytic ammonia hydrogen production system and hydrogen production method

Abstract

The invention relates to an ammonia electrolysis hydrogen production system. An anode chamber and a cathode chamber are communicated through an electrolyte diaphragm to jointly form a closed electrolytic bath system; the bottom of the anode is immersed in the anolyte of the anode chamber to generate ammoxidation reaction to generate nitrogen, the anolyte is a mixed alkaline solution of an alkaline solution and ammonia water, and the bottom of the cathode is immersed in the catholyte of the cathode chamber to generate hydrogen evolution reaction to generate hydrogen; the cathode electrolyte is a mixed alkaline solution of an alkaline solution and ammonia water, the anode and the cathode are electrically connected with a positive electrode and a negative electrode of an external power supply respectively, and the electrolyte diaphragm is a porous diaphragm and is used for physically isolating nitrogen generated by the anode from hydrogen generated by the cathode and allowing hydroxyl ions generated by the cathode to migrate to the anode, so that charge balance of the cathode and the anode is realized. The invention further relates to a hydrogen production method based on the electrolytic ammonia hydrogen production system. According to the method, low-energy-consumption, low-cost and high-stability green hydrogen preparation is realized, and key technical support is provided for promoting large-scale and commercialized development of the green hydrogen industry.

Description

Technical Field

[0001] This invention relates to the field of hydrogen production, and more specifically to an electrolytic ammonia hydrogen production system and a hydrogen production method. Background Technology

[0002] Hydrogen energy is considered a core component of the future clean energy system, but its large-scale commercial application has long been limited by two major bottlenecks: the challenge of economical and efficient production and the challenge of safe and convenient storage and transportation. These two factors together have increased the total life cycle cost of hydrogen energy and constrained the large-scale development of the green hydrogen (hydrogen produced from renewable energy electricity) industry.

[0003] First, there are technological bottlenecks in hydrogen production.

[0004] The current mainstream method for producing green hydrogen is water electrolysis. The theoretical decomposition voltage for water electrolysis is 1.23V, corresponding to a theoretical minimum power consumption of approximately 39.4 kWh / kgH2. However, due to the slow kinetics of the oxygen evolution reaction (OER) and high electrode overpotential during electrolysis, the actual operating voltage needs to reach 1.8V~2.4V, causing the actual power consumption to climb to over 50~55 kWh / kgH2. Electricity costs account for more than 70% of the cost of hydrogen production, making it difficult for green hydrogen to compete with fossil fuel-based hydrogen production (such as natural gas reforming), especially when renewable energy electricity prices fluctuate, further limiting its economic viability.

[0005] Hydrogen production through water electrolysis mainly includes two technical routes: alkaline water electrolysis (AWE) and proton exchange membrane (PEM) water electrolysis. AWE requires corrosion-resistant metals such as nickel and stainless steel as electrode and tank materials to resist corrosion from strongly alkaline electrolytes (such as KOH and NaOH solutions), resulting in a bulky system. Furthermore, its core membrane (such as asbestos membranes or polyphenylene sulfide (PPS) membranes) is prone to degradation under strong alkaline and high-pressure conditions, limiting its lifespan and requiring frequent replacement and maintenance, further increasing operating costs. While PEM offers advantages such as rapid start-up and shutdown and a wide load adjustment range, its core relies on two scarce and expensive materials: firstly, precious metal catalysts such as platinum (Pt) and iridium (Ir); and secondly, the complex and costly preparation process of perfluorosulfonic acid proton exchange membranes (such as Nafion membranes). This results in a high cost for PEM electrolyzers, becoming the biggest obstacle to the large-scale promotion of PEM technology.

[0006] Secondly, there are technological bottlenecks in hydrogen energy storage and transportation.

[0007] Hydrogen is the least dense gas in nature, and its storage and transportation require specialized processes, resulting in low efficiency, high cost, and poor safety. High-pressure gaseous hydrogen storage requires compressing hydrogen to 35-70 MPa, posing safety risks and consuming a lot of energy. Cryogenic liquid hydrogen storage requires cooling hydrogen to -253°C, consuming enormous amounts of energy and requiring extremely high insulation performance from the container. Solid-state hydrogen storage relies on hydrogen storage materials such as metal hydrides, but existing materials generally suffer from low gravimetric hydrogen storage density and demanding hydrogen absorption and desorption conditions. The inefficiency and high cost of these storage and transportation methods severely limit the commercial application of hydrogen energy.

[0008] To overcome the bottlenecks in hydrogen energy storage and transportation, academia and industry have proposed the concept of "hydrogen carriers," which convert hydrogen into easily stored and transportable chemicals, and then convert them back into hydrogen at the point of use using technological means. Ammonia (NH3) is considered one of the most promising hydrogen carriers. Liquid ammonia can be liquefied at room temperature with only about 1 MPa pressure or -33°C, and its hydrogen density is as high as 121 kgH2 / m³. 3 It is much higher than that of liquid hydrogen (70.8 kg H2 / m³). 3 (-253℃) means that ammonia has a greater advantage in storage and transportation volume and efficiency when transporting the same mass of hydrogen. Ammonia is one of the world's largest-produced chemical products, and its synthesis (Haber-Bosch process), storage (atmospheric pressure storage tanks), and transportation (liquid ammonia ships, tank trucks) technologies are very mature, with well-developed infrastructure and relatively low costs. Ammonia molecules contain only nitrogen (N) and hydrogen (H) elements and no carbon. Its conversion into hydrogen does not produce carbon dioxide, ensuring zero carbon emissions throughout the entire process, which aligns with the needs of the green hydrogen industry.

[0009] The traditional technology for converting ammonia into hydrogen is ammonia cracking, which involves decomposing ammonia into nitrogen (N2) and hydrogen (H2) at high temperatures (>600℃) and under the action of a catalyst. However, the high reaction temperature of this technology leads to high energy consumption, slow equipment start-up and shutdown (requiring several hours for heating / cooling), and the mixing of nitrogen and hydrogen in the products requires an additional separation device to purify the hydrogen, increasing the complexity and cost of the system.

[0010] In contrast, directly converting ammonia into hydrogen and nitrogen under mild conditions exhibits significant advantages. The theoretical decomposition voltage of ammonia electrolysis is only 0.06V, far lower than the 1.23V of water electrolysis, which theoretically can significantly reduce the power consumption for hydrogen production. Ammonia electrolysis typically operates at ambient temperature to 150℃ and low pressure (<1MPa), requiring no high-temperature reactor. The system structure is simple, with rapid start-up and shutdown, and can be flexibly coupled with highly volatile renewable energy sources such as wind and solar power. During the electrolysis process, the ammonia oxidation reaction (AOR) occurs at the anode to generate nitrogen gas (2NH3 + 6OH). - →N2 + 6H2O + 6e - The hydrogen evolution reaction (HER) occurs at the cathode to produce hydrogen gas (6H2O + 6e). -→3H2+6OH - The two are physically separated by a membrane, allowing for the production of high-purity hydrogen (2NH3→N2+3H2) without additional purification. AOR exhibits good reaction kinetics on non-precious metal catalysts (such as nickel and nickel-based alloys), and is expected to reduce dependence on precious metals such as platinum and iridium, thereby lowering catalyst costs.

[0011] The current mainstream ammonia electrolysis hydrogen production technology is based on a liquid alkaline electrolyte system. A typical scheme involves mixing ammonia with a 1-10M potassium hydroxide (KOH) or sodium hydroxide (NaOH) aqueous solution as the electrolyte, and using an asbestos membrane or polyimide membrane as the ion conduction and gas separation medium to achieve the electrolytic conversion of ammonia. However, high-concentration alkaline solutions are prone to corrosion (leading to aging of electrode and tank materials), leakage (increasing system maintenance difficulty), and carbonation (absorbing CO2 from the air to form carbonates). While commonly used asbestos membranes are inexpensive, they are easily degraded in a strongly alkaline environment over long periods, exhibiting poor durability, and asbestos materials pose potential hazards to the environment and human health. During ammonia electrolysis, the anode catalyst is easily poisoned by the adsorption of by-reaction products (such as nitrogen-containing intermediates), leading to catalytic activity decay, shortened electrode lifespan, frequent electrode replacement, and increased operating costs. Summary of the Invention

[0012] In order to solve the problems of high energy consumption, high cost, and difficulty in hydrogen storage and transportation in the existing technology, the present invention aims to provide an electrolytic ammonia hydrogen production system and hydrogen production method, which can efficiently produce hydrogen in a low-energy-consumption and low-material-cost manner.

[0013] According to the electrolytic ammonia-to-hydrogen system of the present invention, it includes an anode chamber, a cathode chamber, an electrolyte membrane, an electrode assembly, and an external power supply; the anode chamber and the cathode chamber are connected through the electrolyte membrane to form a closed electrolytic cell system; the electrode assembly includes an anode and a cathode, the bottom of the anode is immersed in the anolyte in the anode chamber to undergo an ammonia oxidation reaction to generate nitrogen gas, the anolyte being a mixed alkaline solution of an alkaline solution and ammonia water; the bottom of the cathode is immersed in the catholyte in the cathode chamber to undergo a hydrogen evolution reaction to generate hydrogen gas, the catholyte being a mixed alkaline solution of an alkaline solution and ammonia water; the anode and cathode are respectively connected to the positive and negative terminals of the external power supply. The system includes an electrical connection, wherein the electrolyte membrane is a porous membrane used to physically isolate the nitrogen gas generated at the anode from the hydrogen gas generated at the cathode, and allows hydroxide ions generated at the cathode to migrate to the anode, thereby achieving charge balance between the anode and cathode. The system also includes a polarity switching device and a detection control unit. The polarity switching device is connected in series between the external power supply and the electrode assembly, and the detection control unit is connected to both the electrode assembly and the polarity switching device. When the detection control unit detects a decrease in current density from the initial value by a preset amount, it reverses the electrical connection between the anode and the cathode, making the original anode the cathode. The high reduction potential of the hydrogen evolution reaction and the generated hydrogen gas are used to remove surface poisoning substances, thereby achieving in-situ regeneration of the catalyst.

[0014] In a preferred embodiment, the concentration of the alkaline solute in the mixed alkaline solution and ammonia water is 1 M / L to 8 M / L, the concentration of ammonia water is 0.5 M / L to 5 M / L, and the molar ratio of alkaline solute to NH3 is (2~10):1.

[0015] In a preferred embodiment, the alkaline solute in the alkaline solution includes at least one of KOH, NaOH, Ca(OH)2, Na2CO3, NaHCO3, K2CO3, KHCO3, NH3H2O, and LiOH.

[0016] In a preferred embodiment, the anode or cathode of the electrode assembly is an electrode supported on an ammonia oxidation or hydrogen evolution catalyst.

[0017] In a preferred embodiment, the catalyst is at least one of Pt, PtIr, PtNi, PtCu or Ni, NiFe, NiCo, NiMo-based catalysts.

[0018] In a preferred embodiment, the Pt-based catalyst of the anode is Pt supported on a titanium dioxide support, and the Pt-based catalyst of the cathode is Pt supported on a carbon support.

[0019] In a preferred embodiment, the electrolyte membrane is selected from asbestos membrane, Zirfon membrane, PPS (polyphenylene sulfide) membrane, and composite porous membrane.

[0020] According to the present invention, the hydrogen production method based on the above-described electrolytic ammonia hydrogen production system includes the following steps: S1, injecting a mixed alkaline solution of the alkaline solution and ammonia water into the anode chamber and the cathode chamber respectively, ensuring that the anode and cathode are completely submerged; S2, activating the external power supply and applying voltage to the anode and cathode, causing the anode to undergo an ammonia oxidation reaction to generate nitrogen gas, and the cathode to undergo a hydrogen evolution reaction to generate hydrogen gas; S3, collecting the nitrogen gas discharged from the anode chamber and the hydrogen gas discharged from the cathode chamber respectively.

[0021] In a preferred embodiment, when the current density of the electrolyzer is detected to decrease by 5%-20% from the initial value, the electrical connection between the anode and cathode is reversed by an external circuit polarity switching device, so that the original poisoned anode becomes the cathode to undergo hydrogen evolution reaction, and the poisoned substances on the electrode surface are removed to achieve catalytic activity regeneration; if the current density is detected to decrease by 5%-20% again, the above polarity switching operation is repeated.

[0022] In a preferred embodiment, the ammonia water serves as a hydrogen carrier, and the hydrogen production method also incorporates the entire industrial chain process of renewable energy power generation → ammonia production → safe storage and transportation of ammonia → on-site electrolysis for hydrogen production. By utilizing the high hydrogen density of ammonia and mature storage and transportation infrastructure, large-scale, long-distance, low-cost hydrogen supply can be achieved.

[0023] The electrolytic ammonia hydrogen production system of this invention uses a mixed electrolyte of alkaline solution and ammonia water in the anode chamber to provide raw materials for the ammonia oxidation reaction, and an alkaline solution in the cathode chamber to ensure the ionic environment required for the hydrogen evolution reaction. An electrolyte membrane is used to achieve gas isolation and hydroxide ion conduction, significantly reducing system costs. Furthermore, by using ammonia as the hydrogen carrier, the system can fully utilize the mature liquefaction and transportation infrastructure of ammonia and its high hydrogen density, effectively solving the industry problems of low efficiency and high cost in large-scale, long-distance hydrogen storage and transportation. Through the directional occurrence of the anode ammonia oxidation reaction and the cathode hydrogen evolution reaction, and the physical isolation of the product gases, high-purity hydrogen can be obtained without additional separation devices, further simplifying the system structure and improving operating efficiency. Ultimately, it achieves low-energy consumption, low-cost, and highly stable green hydrogen production, providing key technical support for promoting the large-scale and commercial development of the green hydrogen industry. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a preferred embodiment of an electrolytic ammonia-to-hydrogen system according to the present invention.

[0025] Figure 2 The graph shows the electrochemical performance of the ammonia electrolysis hydrogen production system in Example 1.

[0026] Figure 3 This is a long-term operational stability curve of the electrolytic ammonia hydrogen production system in Example 2. Detailed Implementation

[0027] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1 As shown, the electrolytic ammonia-to-hydrogen system according to the present invention includes an anode chamber, a cathode chamber, an electrolyte membrane, an electrode assembly, and an external power supply. The anode chamber and cathode chamber are connected through the electrolyte membrane to form a closed electrolytic cell system. The electrode assembly includes an anode and a cathode, with its bottom immersed in the electrolyte in the anode and cathode chambers, respectively, and is electrically connected to the positive and negative terminals of the external power supply. Specifically, the system also includes a polarity switching device and a detection and control unit. The polarity switching device is connected in series between the external power supply and the electrode assembly, and the detection and control unit is signal-connected to both the electrode assembly and the polarity switching device. When the detection and control unit detects a decrease in current density from the initial value by a preset amount (5%-20%, preferably 10%), and determines that the attenuation is due to performance degradation of the anode catalyst caused by the adsorption of nitrogen-containing intermediates, the polarity switching device can be automatically or manually triggered to reverse the electrical connection between the anode and cathode, making the original anode the cathode. The high reduction potential of the hydrogen evolution reaction and the generated hydrogen gas are used to remove surface poisoning substances, achieving in-situ catalyst regeneration and significantly extending the system lifespan.

[0029] The electrolyte is a mixed alkaline solution of a suitable concentration of alkaline solution and ammonia. The concentration of the alkaline solute in the alkaline solution can be adjusted between 0.1 M / L and the saturation concentration of the solute (preferably, the molar concentration of the alkaline solute is 1 M / L to 8 M / L, for example, 5 M / L), and the concentration of the ammonia can be adjusted between 0.1 M / L and the saturation concentration of ammonia (preferably, the molar concentration of NH3 is 0.5 M / L to 5 M / L, for example, 1 M / L). The molar ratio of the alkaline solute to NH3 is (2~10):1, for example, 5:1. Specific types of alkaline solutions include, but are not limited to, KOH, NaOH, Ca(OH)2, Na2CO3, NaHCO3, K2CO3, KHCO3, NH3H2O, LiOH, etc. In two preferred embodiments, both the anode chamber and the cathode chamber are filled with a mixed alkaline solution (electrolyte) of 5 M potassium hydroxide (KOH) + 1 M ammonia.

[0030] The ammonia electrolysis system of this invention exhibits good catalyst compatibility. The anode or cathode is an electrode supported on an ammonia oxidation or hydrogen evolution catalyst, preferably at least one of Pt, PtIr, PtNi, PtCu, or Ni, NiFe, NiCo, or NiMo-based catalysts. The use of a Pt-based catalyst in the examples is to rapidly verify the system's electrochemical performance and the effectiveness of the polarity switching strategy in a laboratory environment. In practical industrial applications, based on the alkaline electrolyte system of this invention, the anode can be completely replaced by non-precious metal catalysts such as Ni-Co alloys or Ni-Cu. Although their single-use activity is lower than Pt, combined with the 'polarity switching regeneration strategy' of this invention, long-term activity can be maintained, thereby further significantly reducing system costs. Therefore, this invention should not be limited to Pt-based catalysts. In a preferred embodiment, platinum (Pt) / titanium mesh electrodes are used (the titanium mesh is a conductive substrate with a Pt-based catalyst supported on its surface).

[0031] In the anode chamber, 2NH3(aq) + 6OH- - →N2(g) + 6H2O + 6e - Ammonia undergoes ammonia oxidation (AOR) at the anode, producing nitrogen gas, which is discharged from the top of the anode chamber, releasing electrons (e). - In the cathode chamber, 6H₂O + 6e⁻ - →3H2(g) + 6OH - Water molecules undergo hydrogen evolution reaction (HER) at the cathode, generating hydrogen gas, which is discharged from the top of the cathode chamber, while hydroxide ions (OH-) are generated. - ).

[0032] The electrolyte membrane, located between the anode and cathode chambers, is a porous membrane, typically made of commercially available asbestos. It physically isolates the nitrogen (N2) generated at the anode from the hydrogen (H2) generated at the cathode, preventing the mixing of these two gases from causing a decrease in product purity or safety risks. Simultaneously, it allows the OH- generated at the cathode to pass through. - The asbestos membrane moves towards the anode, replenishing the OH⁻ consumed in the anode reaction, forming an ion cycle, achieving charge balance between the anode and cathode, and ensuring circuit continuity. Electrons released from the anode flow to the cathode through an external power source (green electricity), forming an electronic circuit, ensuring that the entire hydrogen production process is carbon-free and meets the requirements for green hydrogen production. It should be understood that the asbestos membrane can be replaced by a Zirfon membrane, a PPS (polyphenylene sulfide) membrane, or a composite porous membrane.

[0033] Example 1

[0034] Mix 5M KOH and 1M NH3 to form the electrolyte for the anode and cathode chambers.

[0035] Using titanium mesh as a substrate and serving as a macroscopic conductive framework, Pt-based catalysts were loaded onto the surface of the titanium mesh using impregnation, spraying, and electrodeposition methods to prepare Pt / titanium mesh electrodes. These electrodes were then cut to sizes matching the chamber and used as the anode and cathode of the system. Specifically, considering corrosion resistance, the anode adopted a Pt@TiO2 / titanium mesh structure (i.e., a platinum catalyst supported on titanium dioxide on a titanium mesh substrate); considering conductivity, the cathode adopted a PtC / titanium mesh structure (i.e., a platinum catalyst supported on carbon on a titanium mesh substrate, with the Pt loading controlled at 1 mg). Both were prepared using the impregnation method, representing different loading forms of Pt-based catalysts on titanium meshes.

[0036] The asbestos diaphragm is fixed in the middle of the electrolytic cell, ensuring that the diaphragm is tightly attached to the chamber wall. The electrolyte is injected into the anode chamber and cathode chamber respectively until the electrodes are completely submerged. The anode and cathode are connected to the positive and negative terminals of an external green power source through wires to complete the system assembly.

[0037] An external power supply was activated, the electrolysis temperature was controlled at 60℃, and the electrolyte flow rate was set to 50-200 rpm. An electrode potential that varied linearly with time was applied, and the current changes of the system at different voltages were recorded. The current response at different potentials is shown below. Figure 2 As shown, the current density increases significantly with increasing potential, indicating that the combination of Pt / titanium mesh electrode and asbestos membrane can effectively drive the electrolysis reaction and achieve stable electrolysis at a low potential of about 1V, which is far lower than the working voltage of 1.8V~2.4V for traditional water electrolysis, thus achieving the technical advantage of low power consumption.

[0038] Example 2

[0039] Based on Example 1, the electrolyte composition of the cathode chamber was optimized. The electrolyte in the anode chamber remained a mixed solution of 5M KOH + 1M NH3, and both the anode and cathode were Pt / titanium mesh electrodes. The remaining chamber structures and diaphragm types (asbestos diaphragms) were completely consistent with Example 1.

[0040] The performance degradation threshold is set at 10%. When the current density decreases by 10% from the initial value, it is determined that the anode catalyst is poisoned due to the adsorption of by-products. At this time, the polarity switching device of the external circuit is used to reverse the electrical connection between the anode and the cathode (the original anode is connected to the negative terminal of the power supply, and the original cathode is connected to the positive terminal of the power supply). After the switch, the originally poisoned anode becomes the cathode, and the hydrogen evolution reaction occurs. The surface poisoning substances are removed or transformed, and the catalytic activity is regenerated. If the current density decreases by 10% again, the above polarity switching operation is repeated.

[0041] After starting the system, maintain the electrolysis temperature at 60℃, and the initial current density in the forward anode and cathode mode is 100 mA / cm². 2The current density in reverse mode after switching is -100 mA / cm². 2 Its potential changes under multiple anode-cathode switching are as follows Figure 3 As shown, the curve fluctuates smoothly overall without significant rise, and the system achieves long-term stable operation for more than 800 hours.

[0042] The hydrogen production method in this embodiment can be embedded in the entire industrial chain of renewable energy power generation → ammonia production → ammonia tanker storage and transportation → on-site electrolysis hydrogen production at hydrogen refueling stations. Ammonia is transported by liquid ammonia tanker trucks and electrolyzed on-site at hydrogen refueling stations to generate hydrogen, which is then directly supplied to fuel cell vehicles.

[0043] This invention revolves around the core technical path of "hydrogen production by electrolysis of ammonia". Through the verification of the aforementioned Examples 1 and 2, it is fully demonstrated that it can effectively overcome the inherent bottlenecks of traditional hydrogen production technologies (including traditional water electrolysis and traditional ammonia electrolysis) and form a new hydrogen production solution that combines low energy consumption, low cost, long life and full-chain adaptability.

[0044] From the perspective of core performance breakthroughs, this invention relies on the low theoretical energy consumption characteristics of ammonia electrolysis (theoretical decomposition voltage of only 0.06V), combined with electrode material optimization (such as differentiated Pt-based catalyst support design) and electrolyzer structure improvement, to stably control the actual electrolysis voltage at around 1V, far lower than the operating voltage of 1.8V~2.4V for traditional water electrolysis. This fundamentally solves the core pain point of "excessive energy consumption and high proportion of operating electricity costs" in the hydrogen production process. At the same time, it uses inexpensive asbestos membranes to replace expensive perfluorosulfonic acid proton exchange membranes and supports the application of non-precious metal or low-precious metal supported catalysts, completely eliminating the dependence on scarce resources such as platinum and iridium and high-priced membrane materials. This significantly reduces the material and manufacturing costs of the electrolyzer, providing a cost basis for the large-scale implementation of the technology.

[0045] In terms of system stability and industrial adaptability, this invention represents a key breakthrough with its unique anode-cathode switching strategy: when the anode becomes poisoned and deactivated due to side reactions (manifested as a 10% performance degradation), the electrode polarity is reversed via an external circuit, turning the original anode into a cathode to participate in the hydrogen evolution reaction. This effectively removes poisonous substances from the electrode surface and regenerates catalytic activity. As shown in Example 2, the system can operate continuously and stably for over 800 hours, solving the problems of "short electrode life and frequent maintenance" in traditional ammonia electrolysis. More importantly, this invention does not design the hydrogen production process in isolation, but rather seamlessly integrates ammonia as a green hydrogen carrier into the entire industrial chain of "renewable energy power generation → ammonia production → safe storage and transportation → on-site electrolysis hydrogen production," leveraging the high hydrogen density of ammonia (liquid hydrogen density 121 kg H2 / m³). 3 With its advantages in mature storage and transportation infrastructure (liquid ammonia tank trucks and storage tanks), it has completely solved the global problem of large-scale, long-distance, and low-cost storage and transportation of hydrogen, realizing a closed loop of "production-storage-transportation-use".

[0046] In summary, this invention, through the innovative design of an electrolytic ammonia technology path, simultaneously addresses four core requirements: low-power hydrogen production, low-cost materials, long system lifespan, and compatibility with hydrogen storage and transportation. It not only provides a new technological option for green hydrogen production but also offers a practical solution for promoting the large-scale and commercial development of the green hydrogen industry through a whole-chain integrated approach, demonstrating significant technological value and promising prospects for industrial application.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims. All aspects not described in detail in this invention are conventional technical content.

Claims

1. An ammonia electrolysis hydrogen production system, characterized by, The hydrogen production system comprises an anode chamber, a cathode chamber, an electrolyte diaphragm, an electrode assembly and an external power source; the anode chamber and the cathode chamber are communicated through the electrolyte diaphragm to jointly form a closed electrolytic cell system; the electrode assembly comprises an anode and a cathode, the bottom of the anode is immersed in an anode electrolyte in the anode chamber to generate nitrogen by ammonia oxidation reaction, the anode electrolyte is a mixed alkaline solution of an alkaline solution and ammonia water, the bottom of the cathode is immersed in a cathode electrolyte in the cathode chamber to generate hydrogen by hydrogen evolution reaction, the cathode electrolyte is a mixed alkaline solution of an alkaline solution and ammonia water, the anode and the cathode are electrically connected with the positive electrode and the negative electrode of the external power source respectively, and the electrolyte diaphragm is a porous diaphragm for physically separating the nitrogen generated by the anode from the hydrogen generated by the cathode and allowing the hydroxyl ions generated by the cathode to migrate to the anode to achieve the charge balance of the anode and the cathode; the system further comprises a polarity switching device and a detection control unit, wherein the polarity switching device is connected in series between the external power source and the electrode assembly, and the detection control unit is signal connected with the electrode assembly and the polarity switching device respectively; when the detection control unit detects that the current density decreases by a preset amplitude from the initial value, the electrical connection relationship of the anode and the cathode is reversed, the original anode becomes a cathode, the high reduction potential of the hydrogen evolution reaction and the generated hydrogen are used to remove the surface toxic substances, and the in-situ regeneration of the catalyst is realized.

2. The ammonia electrolysis hydrogen production system of claim 1, wherein, In the mixed alkaline solution of the alkaline solution and the ammonia water, the concentration of the alkaline solute is 1M / L-8M / L, the concentration of the ammonia water is 0.5M / L-5M / L, and the molar ratio of the alkaline solute to NH3 is (2-10):

1.

3. The ammonia electrolysis hydrogen production system of claim 1, wherein, The alkaline solute in the alkaline solution comprises at least one of KOH, NaOH, Ca(OH)2, Na2CO3, NaHCO3, K2CO3, KHCO3, NH3H2O and LiOH.

4. The ammonia electrolysis hydrogen production system of claim 1, wherein, The anode or the cathode of the electrode assembly is an electrode loaded with an ammonia oxidation or hydrogen evolution catalyst.

5. The ammonia electrolysis hydrogen production system of claim 4, wherein, The catalyst is at least one of Pt, PtIr, PtNi, PtCu or Ni, NiFe, NiCo, NiMo-based catalysts.

6. The ammonia electrolysis hydrogen production system of claim 4, wherein, The Pt-based catalyst of the anode is Pt loaded on a titanium dioxide carrier, and the Pt-based catalyst of the cathode is Pt loaded on a carbon carrier.

7. The ammonia electrolysis hydrogen production system of claim 1, wherein, The electrolyte diaphragm is selected from one of an asbestos diaphragm, a Zirfon membrane, a PPS diaphragm and a composite porous membrane.

8. A method of hydrogen production based on the system for hydrogen production by electrolysis of ammonia according to any one of claims 1 to 6, characterized in that, The hydrogen production method comprises the following steps: S1, injecting the mixed alkaline solution of the alkaline solution and the ammonia water into the anode chamber and the cathode chamber respectively to ensure that the anode and the cathode are completely immersed; S2, starting the external power source to apply a voltage to the anode and the cathode to make the anode generate nitrogen by ammonia oxidation reaction and the cathode generate hydrogen by hydrogen evolution reaction; S3, collecting the nitrogen discharged from the anode chamber and the hydrogen discharged from the cathode chamber respectively.

9. The method of claim 8, wherein, When the current density of the electrolytic cell is monitored to decrease by 5%-20% compared with the initial value, the electrical connection relationship between the anode and the cathode is switched by an external circuit polarity switching device, so that the original poisoned anode is converted into a cathode to generate hydrogen evolution reaction, and the toxic substances on the electrode surface are removed to realize catalytic activity regeneration; if the current density is monitored to decrease by 5%-20% again, the above polarity switching operation is repeated.

10. The method of claim 8, wherein, The ammonia water acts as a hydrogen carrier, and the hydrogen production method further embeds a full industrial chain process of renewable energy power generation, ammonia production, ammonia safe storage and transportation, and on-site electrolysis hydrogen production, so that the high hydrogen density of ammonia and the mature storage and transportation infrastructure are utilized to realize large-scale, long-distance and low-cost supply of hydrogen.

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