Integrated equipment for synthesizing ammonia by reducing nitrate through electro-catalysis

Abstract

The invention discloses integrated equipment for synthesizing ammonia through electro-catalysis nitrate radical reduction, and relates to the technical field of crossing of water treatment and resource recovery. A main cavity is supported by the tops of the supporting legs. A bipolar membrane sealing and separating assembly, an anode chamber assembly and a cathode chamber rotational flow reaction and separation assembly are respectively arranged in the main cavity, and an inner cavity of the main cavity is divided into an upper anode chamber and a lower cathode chamber by the bipolar membrane sealing and separating assembly; through systematic in-situ cooperation of the anode chamber assembly, the bipolar membrane sealing and separating assembly and the cathode chamber rotational flow reaction and separation assembly, organic unification of efficient conversion of nitrate radicals, high-selectivity recovery of ammonia products, self-stabilization of a reaction microenvironment and minimization of process energy consumption is realized by means of precise design and cooperation of all the parts; the core pain points of reaction separation and separation, serious mass transfer limitation, easy catalyst inactivation and amplified operation instability of a traditional device are specifically solved, and the industrial requirements of low-concentration wastewater treatment and distributed green ammonia synthesis are met.

Description

Technical Field

[0001] This invention relates to the field of water treatment and resource recycling, specifically to an integrated device for the electrocatalytic reduction of nitrate to synthesize ammonia. Background Technology

[0002] Electrocatalytic nitrate reduction to ammonia synthesis technology is a key frontier in the strategic green chemical industry direction of treating heavy nitrate pollution in water bodies and synthesizing green ammonia. Its technological efficiency directly affects the ecological security of water bodies, the closed-loop efficiency of the nitrogen cycle, and the sustainable supply of non-carbon-based energy carriers. With the increasing global demands for pollution reduction, carbon reduction, and resource recycling, the development of integrated nitrate-to-ammonia production equipment with high conversion efficiency, low energy consumption, stable operation, and adaptability to complex water qualities has become a core link that urgently needs to be broken through in the fields of environmental protection and new energy.

[0003] The core contradiction of existing integrated electrocatalytic nitrate reduction ammonia synthesis equipment lies in the complex conflict between the environmental protection and resource utilization sectors' combined demands for efficient denitrification, highly selective ammonia synthesis, low energy consumption, and stable operation, and the existing equipment's low efficiency, high energy consumption, difficult separation, and scale-up instability. The mass transfer of nitrate, catalytic reduction, ammonia separation, and reaction regulation should ideally be a tightly coupled closed-loop process. However, traditional technologies have long relied on external series designs (separate reaction and separation units) and immobilized operation modes (fixed electrodes, flow rates, and processes), making them unsuitable for real-world scenarios with large fluctuations in wastewater concentration and complex composition. They also fail to meet the stringent requirements of green ammonia synthesis for purity, power consumption, and scale, leading to three major systemic defects: First, the reaction, separation, and regulation are fragmented, resulting in low energy efficiency and selectivity; second, traditional electrocatalytic reactors and back-end separation methods cause ammonia to accumulate in the reaction zone. This process can lead to severe alkalization of the cathode, resulting in catalyst passivation and deactivation, and exacerbating hydrogen evolution side reactions. Furthermore, ammonia separation relies on high-energy-consuming distillation, creating an economic dilemma where separation energy consumption exceeds synthesis power consumption. Secondly, the high energy consumption and cost hinder industrialization. To overcome the limitations of low-concentration mass transfer, traditional devices often employ high voltage or low flow rates, resulting in persistently high power consumption per unit of ammonia production, with levelized cost far exceeding that of traditional ammonia production. In addition, the discrete design requires a large footprint and is complex, further increasing investment and maintenance costs. Simultaneously, there is a significant scale-up effect and poor operational stability. When scaling up from the laboratory to industrial scale, traditional reactors are prone to problems such as uneven flow fields, deteriorated mass transfer, and uncontrolled temperature / pH gradients, causing a sharp drop in yield per unit area. Moreover, the lack of in-situ monitoring and real-time control capabilities makes it difficult to cope with water quality fluctuations, resulting in short continuous operating times and a significant gap from the requirements for stable industrial-grade operation.

[0004] Therefore, we propose an integrated device for the electrocatalytic reduction of nitrate to synthesize ammonia, in order to solve the problems mentioned above. Summary of the Invention

[0005] The purpose of this invention is to provide an integrated device for the electrocatalytic reduction of nitrate to synthesize ammonia, which achieves the organic unity of efficient nitrate conversion, highly selective recovery of ammonia products, self-stabilization of the reaction microenvironment, and minimization of process energy consumption. It specifically addresses the core pain points of traditional devices, such as reaction separation and fragmentation, severe mass transfer limitations, easy catalyst deactivation, and unstable scale-up operation. It is suitable for industrial-grade needs such as low-concentration wastewater treatment and distributed green ammonia synthesis.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an integrated device for electrocatalytic reduction of nitrate to synthesize ammonia, comprising support legs;

[0007] The main cavity is supported at the top of the supporting leg;

[0008] The main cavity is equipped with a bipolar membrane sealing and separating assembly, an anode chamber assembly, and a cathode chamber cyclone reaction separation assembly. The bipolar membrane sealing and separating assembly divides the inner cavity of the main cavity into an upper anode chamber and a lower cathode chamber, and provides a directional ion conduction channel for the anode and cathode chambers to alleviate cathode alkalization.

[0009] The anode chamber assembly is disposed inside the anode chamber and includes a shape-stabilized anode plate, an anode liquid circulation inlet, and an anode liquid circulation outlet;

[0010] The cathode chamber cyclone reaction separation component is disposed inside the cathode chamber and includes a three-dimensional porous catalytic electrode, an aeration head, a hollow fiber hydrophobic membrane bundle, and a tangential feed inlet;

[0011] The tangential feed inlet is located on the side wall of the cathode chamber and is used to allow the wastewater to enter tangentially and form a swirling flow.

[0012] The three-dimensional porous catalytic electrode is disposed inside the cathode chamber, and the water outlet of the tangential feed inlet tangentially scours the three-dimensional porous catalytic electrode.

[0013] The hollow fiber hydrophobic membrane bundles are interspersed in the internal pores of the three-dimensional porous catalytic electrode, and the hollow fiber hydrophobic membrane bundles are used to permeate and collect the ammonia gas generated by the reaction on the electrode surface;

[0014] The aeration head is installed at the bottom of the cathode chamber, and the top of the aeration head has multiple micropores, all of which face the bottom of the three-dimensional porous catalytic electrode.

[0015] Preferably, the bipolar membrane sealing and separating assembly includes a sealing gasket, the outer surface of which is grooved and connected to the inner surface of the main cavity, a sealing frame is connected to the inner surface of the sealing gasket, and the bipolar membrane body is connected to the inner surface of the sealing frame.

[0016] Preferably, the anode chamber assembly further includes an insulating partition and an exhaust port. The outer surface of the insulating partition is connected to the inner surface of the anode chamber, and the inner surface of the insulating partition is connected to the outer surface of the shape-stabilized anode plate. The shape-stabilized anode plate is used to undergo the oxygen evolution reaction.

[0017] Preferably, the top of the stable anode plate is fixedly connected to an anode terminal, and the top of the anode terminal penetrates the upper end cap of the main cavity and is connected to the positive terminal of the DC power supply. The outer surface of the anode terminal is fitted with a first insulating sealing sleeve.

[0018] Preferably, the anolyte circulation inlet and anolyte circulation outlet are respectively located on the lower and upper side walls of the anode chamber, the bottom of the exhaust port is connected to the top of the anode chamber, and the exhaust port penetrates the upper end cap of the main cavity.

[0019] Preferably, the cathode chamber cyclone reaction separation assembly further includes two tetrafluoroethylene sealing rings and an ammonia-rich liquid outlet. The inner surfaces of the two tetrafluoroethylene sealing rings are connected to the outer surface of the three-dimensional porous catalytic electrode. A miniature pH sensor and a dissolved ammonia concentration sensor are inserted into the pores of the three-dimensional porous catalytic electrode. The miniature pH sensor is used to monitor the pH value of the cathode reaction zone in real time, and the dissolved ammonia concentration sensor is used to monitor the concentration of dissolved ammonia in the cathode chamber in real time.

[0020] Preferably, a pressure ring is connected to the top of the aeration head, and the outer surface of the pressure ring is connected to the inner surface of the cathode chamber. A temperature sensor is embedded in the interlayer of the side wall of the cathode chamber, and the temperature sensor is used to monitor the temperature of the reaction zone.

[0021] Preferably, the aeration head is used to generate microbubbles, and the swirling flow field is disturbed during the rise of the bubbles to enhance mass transfer. The bottom of the aeration head is connected to an air inlet, and the top of the hollow fiber hydrophobic membrane bundle is connected to a membrane bundle fixing seat.

[0022] Preferably, the top of the membrane bundle holder is connected to a gas collection chamber, the outer surface of the gas collection chamber is connected to a gas outlet, the bottom of the three-dimensional porous catalytic electrode is fixedly connected to a cathode terminal, and the bottom of the cathode terminal penetrates the lower end cap of the main cavity and is connected to the negative terminal of a DC power supply.

[0023] Compared with the prior art, the beneficial effects of the present invention are: In this invention, through the systematic in-situ synergy of the anode chamber assembly, the bipolar membrane sealing and separation assembly, and the cathode chamber cyclone reaction separation assembly, and relying on the precise design and coordination of each component, the organic unity of efficient nitrate conversion, highly selective recovery of ammonia products, self-stabilization of the reaction microenvironment, and minimization of process energy consumption is achieved. It specifically addresses the core pain points of traditional devices, such as fragmented reaction separation, severe mass transfer limitations, easy catalyst deactivation, and unstable scale-up operation. It is suitable for industrial-grade needs of low-concentration wastewater treatment and distributed green ammonia synthesis. Firstly, the anode chamber assembly adopts an integrated layout where the annular region of the main cavity and the shape-stabilized anode plate are closely attached to the bipolar membrane body. This, combined with an independent acid circulation loop formed by the anolyte circulation inlet and outlet, and an insulating partition defining the reaction area, along with the anode terminals and a first insulating sealing sleeve ensuring power supply safety, localizes the oxygen evolution reaction. Hydroxide ions dissociated from the bipolar membrane body are efficiently received by the shape-stabilized anode plate and removed through acid circulation, creating a stable driving force for the directional migration of hydrogen ions on the cathode side. Simultaneously, the insulating partition and the first insulating sealing sleeve work together to prevent cross-contamination between anode and cathode products and the electrolyte. The exhaust port allows for timely discharge of oxygen evolution reaction products, further ensuring reaction stability. This effectively solves the problem of poor reaction efficiency and instability caused by disordered ion migration in traditional devices, providing a stable reaction substrate for the directional synthesis of ammonia, ensuring the purity of subsequent ammonia resource recovery, and balancing water treatment compliance with high-value resource utilization requirements. Secondly, the bipolar membrane sealing and separation assembly adopts a composite pressure-bearing sealing design consisting of a sealing frame and fluororubber gaskets, which rigidly fixes the bipolar membrane body as a directional ion guiding layer between the anode and cathode chambers. This structure ensures no risk of liquid cross-contamination under the pressure difference of the swirling flow field in the cathode chamber through the pressure-bearing performance of the sealing frame and the sealing effect of the fluororubber gaskets. The bipolar membrane body can accurately realize the on-demand and fixed-point delivery of hydrogen ions to the cathode, precisely replenishing the consumption of the ammonia synthesis reaction. It fundamentally buffers the cathode alkalization problem and solves the fundamental contradiction of the traditional device, which is caused by the intensified competition for hydrogen evolution of the catalyst and rapid deactivation due to local acid-base loss. This extends the service life of the catalyst, reduces industrial operation and maintenance costs, and provides a guarantee for continuous operation in the intersection of water treatment and resource recovery. Finally, the cathode chamber cyclone reaction separation component serves as the core, employing a tangential feed inlet to drive strong cyclone flow within the three-dimensional porous catalytic electrode. This is coupled with an embedded distribution of hollow fiber hydrophobic membrane bundles via a membrane bundle holder, and a microporous air-lift formation from the bottom aeration head, all linked together. A PTFE sealing ring ensures the cavity is sealed and the three-dimensional porous catalytic electrode is fixed in position. The cyclone field formed by the fluid introduced through the tangential feed inlet forces convection, thoroughly breaking down the mass transfer boundary layer under low-concentration conditions. This effectively solves the industry problem of uneven flow field and deteriorated mass transfer during scale-up, significantly improving the nitrate conversion efficiency in water treatment. The generated ammonia is separated by the hollow fiber hydrophobic membrane bundles and separated from the aeration head by bubble air-lift. The ammonia is immediately removed from the reaction zone, collected in the gas collection chamber, and discharged through the gas outlet. This process simultaneously consumes hydroxide ions to achieve pH self-stabilization, and the product ammonia is enriched in the gas phase, replacing the traditional high-energy-consuming distillation process. The ammonia-rich liquid outlet can simultaneously discharge the treated wastewater, reducing separation energy consumption and improving ammonia recovery purity. The cathode terminal, in conjunction with the second insulating sealing sleeve, achieves uniform power supply in the center, further ensuring reaction stability. Through the synergistic effect of its components, this module overcomes the three major parallel challenges of limited mass transfer, high separation energy consumption, and deteriorating reaction environment in traditional technologies, significantly improving current efficiency, product selectivity, and system economy, perfectly meeting the dual demands of the intersection of water treatment and resource recovery. Attached Figure Description

[0024] Figure 1 This is a perspective view of the main structure in this invention; Figure 2 This is a three-dimensional view of the structure from below in this invention; Figure 3 This is a three-dimensional cross-sectional view of the structure in this invention; Figure 4 This is a schematic diagram showing the installation positions of the anode chamber assembly, the bipolar membrane sealing and separating assembly, and the cathode chamber cyclone reaction separation assembly in this invention. Figure 5 This is a schematic diagram showing the installation position of the anode chamber assembly and the bipolar membrane sealing and separating assembly in this invention. Figure 6 This is a schematic diagram showing the installation positions of the sealing frame, the sealing frame, and the bipolar membrane body in this invention. Figure 7 This is a schematic diagram of the installation position of the cathode chamber cyclone reaction separation component in this invention; Figure 8 This is a schematic diagram showing the installation positions of the gas collecting chamber, gas outlet, and tangential feed inlet in this invention. Figure 9 This is a schematic diagram showing the installation positions of the hollow fiber hydrophobic membrane bundle, the membrane bundle fixing seat, and the gas collection cavity in this invention.

[0025] In the diagram: 100, Support foot; 200, Main cavity; 300, Bipolar membrane sealing and partition assembly; 301, Sealing gasket; 302, Sealing frame; 303, Bipolar membrane body; 400, Anode chamber assembly; 401, Insulating partition; 402, Shape-stabilized anode plate; 403, Anode terminal; 404, First insulating sealing sleeve; 405, Anode liquid circulation inlet; 406, Anode liquid circulation outlet; 407, Exhaust port; 500. Cathode chamber cyclone reaction separation assembly; 501, PTFE sealing ring; 502, three-dimensional porous catalytic electrode; 503, pressure ring; 504, aeration head; 505, micropores; 506, air inlet; 507, hollow fiber hydrophobic membrane bundle; 508, membrane bundle fixing seat; 509, gas collection chamber; 510, air outlet; 511, tangential feed inlet; 512, ammonia-rich liquid outlet; 513, cathode terminal; 514, second insulating sealing sleeve. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] like Figures 1-2 As shown, this embodiment discloses an integrated device for electrocatalytic reduction of nitrate to synthesize ammonia, including a support foot 100; The main cavity 200 is supported at the top of the support leg 100; In this embodiment of the invention, the support foot 100 is made of corrosion-resistant stainless steel and is equipped with adjustable feet. It is evenly distributed around the bottom of the main cavity 200 and has an anti-slip rubber pad at the bottom. This provides stable support for the main cavity 200, ensuring that the equipment remains horizontal and stable during operation. It can also adapt to the slight unevenness of different installation surfaces, buffer the vibration during operation, and create a reliable physical environment for the internal precision electrochemical reaction, which is in line with the mechanical balance principle of the overall equipment installation.

[0028] like Figure 3 As shown, the main cavity 200 is provided with a bipolar membrane sealing and separating assembly 300, an anode chamber assembly 400, and a cathode chamber cyclone reaction separation assembly 500. The bipolar membrane sealing and separating assembly 300 divides the inner cavity of the main cavity 200 into an upper anode chamber and a lower cathode chamber, and provides a directional ion conduction channel for the anode and cathode chambers to alleviate cathode alkalization. In this embodiment of the invention, the main cavity 200 serves as the core pressure vessel, with its inner wall lined with a PVDF anti-corrosion layer. This layer can withstand the fluid shear force generated by the strong swirling flow in the cathode chamber and resist electrochemical corrosion, thus extending the service life of the equipment. Secondly, the bipolar membrane sealing and separating component 300 is horizontally embedded in the annular groove in the middle of the main cavity 200 and is coaxial with the cavity axis. This precisely divides the reaction space from a physical structure perspective, enabling the cathode chamber and anode chamber to function independently and allowing for directional ion migration, thus laying the foundation for efficient collaborative operation in the future.

[0029] like Figure 4 as well as Figure 6 As shown, the anode chamber assembly 400 is disposed inside the anode chamber and includes a shape-stabilized anode plate 402, an anode liquid circulation inlet 405, and an anode liquid circulation outlet 406. In this embodiment of the invention, the anode chamber assembly 400 first forms a dedicated chamber for the oxygen evolution reaction. The stable anode plate 402 is made of titanium-based coated material and is arranged in close contact with the bipolar membrane sealing and separating assembly 300, which greatly shortens the receiving path of hydroxide ions and improves the proton supply response speed. The independent anolyte circulation loop forms a bottom-in, top-out flow channel design through the anolyte circulation inlet 405 and the anolyte circulation outlet 406, which conforms to the principle of thermal convection. It can continuously remove the heat of reaction and maintain the uniformity of electrolyte concentration, ensuring that the anode reaction proceeds stably and efficiently.

[0030] like Figure 4 as well as Figure 7 As shown, the cathode chamber cyclone reaction separation component 500 is disposed inside the cathode chamber and includes a three-dimensional porous catalytic electrode 502, an aeration head 504, a hollow fiber hydrophobic membrane bundle 507, and a tangential feed inlet 511. The tangential feed inlet 511 is opened on the side wall of the cathode chamber, and the tangential feed inlet 511 is used to allow the wastewater to be treated to enter tangentially and form a swirling flow; The three-dimensional porous catalytic electrode 502 is located inside the cathode chamber, and the three-dimensional porous catalytic electrode 502 is tangentially flushed in the direction of water outlet from the feed inlet 511. like Figure 8 As shown, hollow fiber hydrophobic membrane bundles 507 are interspersed in the internal pores of the three-dimensional porous catalytic electrode 502, and the hollow fiber hydrophobic membrane bundles 507 are used to permeate and collect the ammonia gas generated by the reaction on the electrode surface. The aeration head 504 is installed at the bottom of the cathode chamber. The top of the aeration head 504 has multiple micropores 505, and all the micropores 505 face the bottom of the three-dimensional porous catalytic electrode 502.

[0031] In this embodiment of the invention, firstly, the cathode chamber cyclone reaction separation component 500 integrates reaction, separation, and control functions, and is the core solution to mass transfer limitations and separation fragmentation. Secondly, the tangential feed inlet 511 is opened along the tangential direction of the cathode chamber sidewall, forcing wastewater to be injected and forming a strong cyclone, thereby achieving forced scouring of the three-dimensional porous catalytic electrode 502 (foamed titanium-based material, porosity 80%-85%). This three-dimensional porous structure not only serves as a catalyst carrier, but its high porosity and tortuous channels also act as a static mixer for the cyclone field, while providing an embedded support framework for the hollow fiber hydrophobic membrane bundle 507, thus achieving a three-in-one fusion of reaction, mass transfer, and separation interfaces in physical space. Furthermore, micropores 505 are opened at the top of the aeration head 504. During the rise of the generated microbubbles, the cyclone field is disturbed to enhance mass transfer, and some of the generated ammonia is stripped in situ. Another part of the ammonia diffuses to the hollow fiber hydrophobic membrane bundle 507 and is selectively permeated, achieving immediate removal of the product and avoiding ammonia accumulation that could lead to side reactions.

[0032] like Figures 5-6 As shown, the bipolar membrane sealing and separating assembly 300 includes a sealing gasket 301. The outer surface of the sealing gasket 301 is grooved and connected to the inner surface of the main cavity 200. A sealing frame 302 is connected to the inner surface of the sealing gasket 301, and a bipolar membrane body 303 is connected to the inner surface of the sealing frame 302.

[0033] In this embodiment of the invention, the sealing gasket 301 is made of fluororubber and is press-fitted with the groove on the inner surface of the main cavity 200. Combined with the sealing frame 302 made of PTFE, a multi-level composite sealing system is formed. This design can effectively resist pressure fluctuations caused by cathode swirling current and long-term electrochemical environment erosion, ensuring that the edge of the bipolar membrane body 303 is absolutely sealed, fundamentally eliminating the risk of electrolyte cross-contamination between the anode and cathode chambers, and ensuring the purity and durability of the ion migration channel.

[0034] like Figure 6 As shown, the anode chamber assembly 400 also includes an insulating partition 401 and an exhaust port 407. The outer surface of the insulating partition 401 is connected to the inner surface of the anode chamber, and the inner surface of the insulating partition 401 is connected to the outer surface of the shape-stabilized anode plate 402. The shape-stabilized anode plate 402 is used to carry out the oxygen evolution reaction.

[0035] In this embodiment of the invention, the insulating partition 401 is made of epoxy resin, which completely electrically isolates the shaped stable anode plate 402 from the main cavity 200 made of metal, preventing short circuits and ensuring that the electric field is fully applied to the electrochemical reaction. Furthermore, the exhaust port 407 is located at the highest point of the anode chamber, which conforms to the natural law of gas rising and can guide the oxygen generated by the anode to be discharged in time, avoiding gas accumulation that affects the electrolyte circulation and the stability of the reaction interface, while maintaining the normal pressure state of the anode chamber.

[0036] like Figures 5-6 As shown, the top of the stable anode plate 402 is fixedly connected to an anode terminal 403, and the top of the anode terminal 403 passes through the upper end cap of the main cavity 200 and is connected to the positive terminal of the DC power supply. The outer surface of the anode terminal 403 is fitted with a first insulating sealing sleeve 404.

[0037] In this embodiment of the invention, firstly, the anode terminal 403 is made of titanium alloy, which has excellent conductivity and corrosion resistance. The bottom is fixed to the stable anode plate 402 by argon arc welding to ensure reliable electrical connection. Secondly, the first insulating sealing sleeve 404 is made of polytetrafluoroethylene, which not only achieves high-voltage electrical insulation, but also ensures dynamic sealing at the terminal penetration point to prevent electrolyte leakage, which is an important guarantee for the safe operation of the equipment.

[0038] like Figures 5-6 As shown, the anolyte circulation inlet 405 and the anolyte circulation outlet 406 are respectively opened on the lower side wall and the upper side wall of the anode chamber. The bottom of the exhaust port 407 is connected to the top of the anode chamber, and the exhaust port 407 penetrates the upper end cap of the main cavity 200.

[0039] In this embodiment of the invention, both the anolyte circulation inlet 405 and the anolyte circulation outlet 406 are welded with stainless steel flange interfaces to facilitate connection with external circulation pipelines. A filter screen is provided at the inlet to prevent impurities from entering. Furthermore, a check valve is installed at the exhaust port 407 after passing through the upper end cap of the main cavity 200, which not only prevents external air from entering and contaminating the anolyte, but also ensures that oxygen is discharged in one direction and maintains stable system pressure.

[0040] like Figures 7-8 As shown, the cathode chamber cyclone reaction separation assembly 500 also includes two PTFE sealing rings 501 and an ammonia-rich liquid outlet 512. The inner surfaces of the two PTFE sealing rings 501 are connected to the outer surface of the three-dimensional porous catalytic electrode 502. A miniature pH sensor and a dissolved ammonia concentration sensor are inserted into the pores of the three-dimensional porous catalytic electrode 502. The miniature pH sensor is used to monitor the pH value of the cathode reaction zone in real time, and the dissolved ammonia concentration sensor is used to monitor the concentration of dissolved ammonia in the cathode chamber in real time.

[0041] In this embodiment of the invention, two tetrafluoroethylene sealing rings 501 are first embedded in the outer periphery of the upper and lower ends of the three-dimensional porous catalytic electrode 502, respectively, to press and seal the electrode from both ends, preventing fluid from short-circuiting around the electrode and ensuring that the swirling flow field fully covers the reaction area; the built-in micro-sensor probe is inserted into the pore in the middle of the electrode, which can directly obtain the core parameters of the reaction microenvironment, provide real-time data support for process control, avoid runaway of temperature and pH gradients, and is the key to solving the problem of scale-up instability.

[0042] like Figures 8-9As shown, the top of the aeration head 504 is connected to a pressure ring 503, and the outer surface of the pressure ring 503 is connected to the inner surface of the cathode chamber. A temperature sensor is embedded in the interlayer of the side wall of the cathode chamber, and the temperature sensor is used to monitor the temperature of the reaction zone.

[0043] In this embodiment of the invention, the pressure ring 503 is made of polytetrafluoroethylene and is fixed to the inner wall of the cathode chamber by bolts. The aeration head 504 is firmly fixed to the center of the bottom of the cathode chamber to ensure uniform aeration. The temperature sensor embedded in the side wall interlayer is a PT100 type, which avoids direct contact with the reaction fluid, reduces the risk of scaling and corrosion, and can monitor the reaction temperature stably for a long time to prevent local overheating from affecting the catalyst activity and membrane separation performance.

[0044] like Figure 9 As shown, the aeration head 504 is used to generate microbubbles. During the rise of the bubbles, the swirling flow field is disturbed to enhance mass transfer. The bottom of the aeration head 504 is connected to the air inlet 506, and the top of the hollow fiber hydrophobic membrane bundle 507 is connected to the membrane bundle fixing seat 508.

[0045] In this embodiment of the invention, firstly, the air inlet 506 at the bottom of the aeration head 504 penetrates the lower end cap of the main cavity 200 and is welded with a stainless steel quick connector, which facilitates connection with an external inert gas pipeline. The size of the bubbles and the aeration intensity can be controlled by adjusting the air inlet pressure. Secondly, the membrane bundle fixing seat 508 is made of polytetrafluoroethylene and has mounting holes that match the hollow fiber hydrophobic membrane bundle 507. The top of the membrane bundle is sealed and fixed with epoxy resin, which not only prevents the hollow fiber hydrophobic membrane bundle 507 from winding and shifting in the swirling flow field, but also ensures the sealing of the gas collection chamber 509 and avoids ammonia leakage.

[0046] like Figures 8-9 As shown, the top of the membrane bundle holder 508 is connected to a gas collecting chamber 509, and the outer surface of the gas collecting chamber 509 is connected to a gas outlet 510. The bottom of the three-dimensional porous catalytic electrode 502 is fixedly connected to a cathode terminal 513, and the bottom of the cathode terminal 513 passes through the lower end cap of the main cavity 200 and is connected to the negative terminal of the DC power supply.

[0047] In this embodiment of the invention, the gas collecting chamber 509 is made of stainless steel and has an annular cavity structure. It is equipped with a guide plate inside, which can guide the ammonia gas to be evenly collected to the gas outlet 510, avoid local gas stagnation, and improve the ammonia collection efficiency. The cathode terminal 513 is made of pure titanium and is led out from the bottom to form an electric field layout that is opposite to the anode terminal 403. This is conducive to the uniform distribution of current in the three-dimensional electrode, suppresses the hydrogen evolution side reaction, and improves the current efficiency.

[0048] like Figure 9 As shown, a second insulating sealing sleeve 514 is fitted on the outer surface of the cathode terminal 513, and the ammonia-rich liquid outlet 512 is opened on the side wall of the cathode chamber.

[0049] In this embodiment of the invention, the second insulating sealing sleeve 514 has the same structure as the first insulating sealing sleeve 404 and is made of polytetrafluoroethylene to ensure the reliability of the bottom electrical seal and prevent cathodic liquid leakage and leakage risk; the ammonia-rich liquid outlet 512 is located in the lower middle part of the side wall of the cathode chamber, in a relatively stable swirling field area, and is higher than the bottom of the cathode chamber. This facilitates the continuous discharge of the tail liquid after the reaction, avoids gas entrainment, and prevents the bottom sediment from flowing out and causing pipeline blockage.

[0050] In operation, the nitrate-containing wastewater is first pressurized by an external pump and injected at high speed into the cathode chamber through the tangential inlet 511. This jet, constrained by the inner wall of the cathode chamber, forms a strong vortex flow field. This vortex flow field continuously and forcefully washes over the three-dimensional porous catalytic electrode 502 filled within the cathode chamber, allowing the wastewater to penetrate its highly porous structure with a porosity of 80%-85%, thereby completely breaking down the mass transfer boundary layer at low concentrations and achieving ultra-fast transport of nitrate ions to the catalyst's active sites. Meanwhile, an external DC power supply provides power to the system through the anode terminal 403 and the cathode terminal 513. Under the action of the electric field, an oxygen evolution reaction occurs on the stable anode plate 402, and oxygen is generated and discharged through the exhaust port 407. The anolyte enters the anode chamber through the anolyte circulation inlet 405 and is discharged through the anolyte circulation outlet 406, continuously removing the heat of reaction and hydroxide ions to ensure the stability of the anode reaction. At the same time, the bipolar membrane body 303 located between the anode and cathode chambers dissociates water molecules under the drive of the electric field, and the generated hydrogen ions migrate directionally to the cathode chamber, replenishing the protons required for the reduction of nitrate ions to synthesize ammonia in situ and as needed. In this process, nitrate ions undergo a highly selective catalytic reduction reaction under the action of a catalyst (such as a copper-based single-atom catalyst) supported on the surface of the three-dimensional porous catalytic electrode 502, and are directionally converted into ammonia. The ammonia generated by the reaction exists mainly in the form of free ammonia in the slightly alkaline cathode microenvironment. At this time, two separation processes are started simultaneously for in-situ instantaneous separation: on the one hand, inert carrier gas such as nitrogen from the aeration head 504 forms uniform microbubbles through the micropores 505 at its top. The rising process of the bubbles not only disturbs and enhances the swirling mass transfer, but also lifts the dissolved ammonia to the gas phase; on the other hand, driven by the concentration gradient, ammonia molecules diffuse into the hollow fiber hydrophobic membrane bundles 507 embedded in the electrode pores, and enter the inner cavity of the membrane fibers through the hydrophobic micropores.

[0051] The mixture of ammonia-containing gas and carrier gas, collected by gas lifting and membrane permeation, converges upwards and enters the gas collection chamber 509 through the membrane bundle fixing seat 508. Finally, it is uniformly discharged through the gas outlet 510 and transported to the external acidic absorption tower, where it is efficiently absorbed and converted into a high-purity ammonium sulfate solution product. The instantaneous removal of ammonia is equivalent to continuously removing the reaction byproduct hydroxide ions. In turn, in conjunction with the hydrogen ions supplied by the bipolar membrane, the pH of the cathode reaction zone is automatically stabilized at the optimal reaction window. This effectively avoids catalyst passivation and deactivation and competitive hydrogen evolution side reactions caused by pH runaway, thereby significantly improving the Faraday efficiency of ammonia synthesis and the long-term operational stability of the catalyst. After the reaction, the nitrate concentration in the wastewater is significantly reduced, transforming it into an ammonia-rich tail liquid. Under the action of swirling flow, it is smoothly discharged from the ammonia-rich liquid outlet 512 located on the side wall, which can be further treated or discharged in compliance with standards. The miniature pH sensor and dissolved ammonia concentration sensor embedded in the electrode, as well as the temperature sensor in the side wall interlayer, feed back the key parameters of the reaction microenvironment to the central control system in real time. The system then dynamically adjusts accordingly. When the pH is too high, the anolyte circulation rate is increased; when the dissolved ammonia concentration is too high, the aeration intensity is increased; when the temperature exceeds the standard, the influent flow rate is reduced; and the current density is adaptively adjusted according to the influent nitrate concentration to cope with fluctuations in influent water quality. This ensures that the entire equipment operates continuously, stably, and efficiently under optimal conditions, realizing the integrated and automated operation of the entire process from nitrate wastewater treatment to green ammonia resource recovery. Through the above-described workflow, the equipment of this invention deeply couples cyclone-enhanced mass transfer, electrocatalytic reduction, in-situ membrane stripping separation, bipolar membrane ion regulation, and process control into a single chamber. This solves the core bottlenecks in traditional technologies, such as the separation of reaction and separation, low mass transfer efficiency at low concentrations, easy catalyst deactivation, and unstable scale-up operation, thus achieving efficient, energy-saving, and stable nitrate resource recovery.

[0052] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An integrated device for electrocatalytic reduction of nitrate to synthesize ammonia, characterized in that: Including support feet (100); The main cavity (200) is supported on the top of the support foot (100). The main cavity (200) is provided with a bipolar membrane sealing and separating assembly (300), an anode chamber assembly (400), and a cathode chamber cyclone reaction separation assembly (500). The bipolar membrane sealing and separating assembly (300) divides the inner cavity of the main cavity (200) into an upper anode chamber and a lower cathode chamber, and provides a directional ion conduction channel for the anode and cathode chambers to alleviate cathode alkalization. The anode chamber assembly (400) is disposed inside the anode chamber and includes a shape-stabilized anode plate (402), an anode liquid circulation inlet (405), and an anode liquid circulation outlet (406). The cathode chamber cyclone reaction separation component (500) is disposed inside the cathode chamber and includes a three-dimensional porous catalytic electrode (502), an aeration head (504), a hollow fiber hydrophobic membrane bundle (507), and a tangential feed inlet (511). The tangential feed inlet (511) is located on the side wall of the cathode chamber, and the tangential feed inlet (511) is used to allow the wastewater to be treated to enter tangentially and form a swirling flow; The three-dimensional porous catalytic electrode (502) is disposed inside the cathode chamber, and the water outlet direction of the tangential feed inlet (511) tangentially washes the three-dimensional porous catalytic electrode (502). The hollow fiber hydrophobic membrane bundle (507) is interspersed in the internal pores of the three-dimensional porous catalytic electrode (502), and the hollow fiber hydrophobic membrane bundle (507) is used to permeate and collect the ammonia gas generated by the reaction on the electrode surface; The aeration head (504) is installed at the bottom of the cathode chamber. The top of the aeration head (504) has multiple micropores (505), and all the micropores (505) face the bottom of the three-dimensional porous catalytic electrode (502).

2. The integrated equipment for electrocatalytic reduction of nitrate to synthesize ammonia according to claim 1, characterized in that: The bipolar membrane sealing and separating assembly (300) includes a sealing gasket (301), the outer surface of the sealing gasket (301) and the inner surface of the main cavity (200) are grooved and connected, the inner surface of the sealing gasket (301) is connected to a sealing frame (302), and the inner surface of the sealing frame (302) is connected to a bipolar membrane body (303).

3. The integrated equipment for electrocatalytic reduction of nitrate to synthesize ammonia according to claim 1, characterized in that; The anode chamber assembly (400) further includes an insulating partition (401) and an exhaust port (407). The outer surface of the insulating partition (401) is connected to the inner surface of the anode chamber, and the inner surface of the insulating partition (401) is connected to the outer surface of the shape-stabilized anode plate (402). The shape-stabilized anode plate (402) is used to carry out the oxygen evolution reaction.

4. The integrated equipment for electrocatalytic reduction of nitrate to synthesize ammonia according to claim 3, characterized in that: The top of the stable anode plate (402) is fixedly connected to an anode terminal (403), and the top of the anode terminal (403) passes through the upper end cap of the main cavity (200) and is connected to the positive terminal of the DC power supply. The outer surface of the anode terminal (403) is fitted with a first insulating sealing sleeve (404).

5. The integrated equipment for electrocatalytic reduction of nitrate to synthesize ammonia according to claim 4, characterized in that: The anolyte circulation inlet (405) and anolyte circulation outlet (406) are respectively opened on the lower side wall and upper side wall of the anode chamber. The bottom of the exhaust port (407) is connected to the top of the anode chamber, and the exhaust port (407) penetrates the upper end cap of the main cavity (200).

6. The integrated equipment for electrocatalytic reduction of nitrate to synthesize ammonia according to claim 1, characterized in that: The cathode chamber cyclone reaction separation assembly (500) also includes two PTFE sealing rings (501) and an ammonia-rich liquid outlet (512). The inner surfaces of the two PTFE sealing rings (501) are connected to the outer surface of the three-dimensional porous catalytic electrode (502). A micro pH sensor and a dissolved ammonia concentration sensor are inserted into the pores of the three-dimensional porous catalytic electrode (502). The micro pH sensor is used to monitor the pH value of the cathode reaction zone in real time, and the dissolved ammonia concentration sensor is used to monitor the concentration of dissolved ammonia in the cathode chamber in real time.

7. The integrated equipment for electrocatalytic reduction of nitrate to synthesize ammonia according to claim 6, characterized in that: The top of the aeration head (504) is connected to a pressure ring (503), and the outer surface of the pressure ring (503) is connected to the inner surface of the cathode chamber. A temperature sensor is embedded in the interlayer of the side wall of the cathode chamber, and the temperature sensor is used to monitor the temperature of the reaction zone.

8. The integrated equipment for electrocatalytic reduction of nitrate to synthesize ammonia according to claim 7, characterized in that: The aeration head (504) is used to generate microbubbles. During the rise of the bubbles, the swirling flow field is disturbed to enhance mass transfer. The bottom of the aeration head (504) is connected to an air inlet (506), and the top of the hollow fiber hydrophobic membrane bundle (507) is connected to a membrane bundle fixing seat (508).

9. The integrated equipment for electrocatalytic reduction of nitrate to synthesize ammonia according to claim 8, characterized in that: The top of the membrane bundle holder (508) is connected to a gas collection chamber (509), and the outer surface of the gas collection chamber (509) is connected to a gas outlet (510). The bottom of the three-dimensional porous catalytic electrode (502) is fixedly connected to a cathode terminal (513), and the bottom of the cathode terminal (513) passes through the lower end cap of the main cavity (200) and is connected to the negative terminal of the DC power supply.

10. An integrated device for electrocatalytic reduction of nitrate to synthesize ammonia according to claim 9, characterized in that: The outer surface of the cathode terminal (513) is fitted with a second insulating sealing sleeve (514), and the ammonia-rich liquid outlet (512) is located on the side wall of the cathode chamber.

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