A hydrogen production system by direct electrolysis of air

Abstract

This invention belongs to the field of electrolytic hydrogen production technology, specifically a direct air electrolysis hydrogen production system. The system includes an energy supply module, an electrolysis hydrogen production module, an electrolyte recycling and regeneration module, and a water vapor self-capture module. The energy supply module, connected to the electrolysis hydrogen production module, provides electrical energy for the hydrogen production reaction. The electrolysis hydrogen production module includes an electrolytic cell; after the electrolyte is introduced into the electrolytic cell, a redox reaction occurs, consuming water and producing hydrogen and oxygen. The electrolyte recycling and regeneration module replenishes the electrolyte with pure water and is connected to both the electrolysis hydrogen production module and the water vapor self-capture module. The water vapor self-capture module absorbs moisture from the air without energy consumption, continuously providing a water source for electrolytic hydrogen production. This system enables direct air electrolysis hydrogen production, with energy consumption comparable to that of industrial electrolysis of pure water for hydrogen production, eliminating the need for additional energy consumption for desalination / purification of non-pure aqueous solutions and for capturing moisture from the air. This system significantly expands the range of hydrogen energy sources and is not limited by time and space, providing technical support for future distributed hydrogen energy deployments.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen electrolysis technology, specifically a direct air electrolysis hydrogen production system. Background Technology

[0002] Hydrogen energy boasts advantages such as wide availability, storability, diverse applications, zero carbon emissions, zero pollution, and high energy density, making it a key component of the future energy sector. Air, as the medium connecting oceans, lakes, and land, is rich in water molecules. Statistics show that the global atmosphere contains approximately 13 trillion tons of water vapor, representing a highly promising source of water for hydrogen production through water electrolysis.

[0003] Currently, there are processes for producing hydrogen by electrolysis using air resources, but these existing processes mainly have the following problems:

[0004] (1) After collecting liquid water through compression refrigeration and other methods, hydrogen is produced by electrolysis. The liquefaction energy consumption generated by this technology will further increase the cost of hydrogen production.

[0005] (2) By using technologies such as radiation cooling and moisture absorption to collect water, water can be collected without energy consumption and then electrolyzed to produce hydrogen. However, this process is severely limited by time and location, making it difficult to produce hydrogen continuously. Due to material limitations, it is difficult to avoid technical bottlenecks such as interference from impurity ions on the oxygen evolution reaction.

[0006] Current air electrolysis hydrogen production technology struggles to simultaneously achieve high current density, high stability, no need for water collection energy consumption, no time or space limitations, and large-scale utilization. Therefore, a novel technology based on sound principles is urgently needed to achieve high-performance, large-scale direct air electrolysis hydrogen production. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a direct air electrolysis hydrogen production system. This system can achieve hydrogen production without additional energy consumption and is not limited by time and space, fundamentally solving the problem of water resource constraints in water electrolysis hydrogen production; at the same time, it helps to ensure that future hydrogen energy conversion is not limited by time and space, completely avoiding the cost and technical difficulties caused by hydrogen transportation.

[0008] To achieve the above-mentioned objectives, the specific technical solution of this invention is as follows:

[0009] An air direct electrolysis hydrogen production system includes an energy supply module, an electrolysis hydrogen production module, an electrolyte recycling and regeneration module, and a water vapor self-capture module, wherein:

[0010] The power supply module, connected to the electrolysis hydrogen production module, is used to provide electrical energy for the hydrogen production reaction;

[0011] An electrolytic hydrogen production module includes an electrolytic cell. When the electrolyte is introduced into the electrolytic cell, an oxidation-reduction reaction occurs, consuming water and producing hydrogen and oxygen.

[0012] The electrolyte circulation and regeneration module is used to replenish pure water from the hygroscopic medium to the electrolyte, and is connected to the electrolytic hydrogen production module and the water vapor self-capture module respectively.

[0013] The water vapor capture module is used to absorb moisture from the air, providing a continuous source of moisture for hydrogen production via electrolysis.

[0014] Preferably, the energy source of the power supply module is electricity converted from traditional coal power or renewable energy (such as solar energy, wind energy, etc.).

[0015] Preferably, the electrolytic cell is any one of an alkaline electrolytic cell, a PEM (proton exchange membrane) electrolytic cell, or an AEM (anion exchange membrane) electrolytic cell, or a combination of any one of these electrolytic cells connected in series or in parallel.

[0016] Preferably, the electrolyte filled in the electrolytic cell is a liquid electrolyte or a solid gel electrolyte. The liquid electrolyte is a liquid with a low saturated water vapor pressure or the ability to absorb water vapor, including alkaline liquid electrolytes, acidic liquid electrolytes, and ionic liquids. Alkaline liquid electrolytes are selected from one of the following alkaline substances: KOH solution, K₂CO₃ solution, KHCO₃ solution, NaOH solution, Na₂CO₃ solution, NaHCO₃ solution, K₃PO₄ solution, CH₃COOK solution, Ca(OH)₂, or combinations thereof. Acidic liquid electrolytes include one of the following acidic substances: H₂SO₄ solution, H₃PO₄ solution, or combinations thereof. Ionic liquids include 1-ethyl-3-methylimidazolium acetate, etc. Organic hygroscopic liquids include PEG, etc. Solid electrolytes are substances that can induce water vapor to undergo phase change and liquefy. Solid gel electrolytes include: polyacrylamide hydrogel, polysulfonate acrylamide hydrogel, polymethylacrylamide hydrogel, polybenzylacrylamide hydrogel, polyphenylacrylamide hydrogel, polyethylacrylamide hydrogel, polytert-butylacrylamide hydrogel, etc., and any hygroscopic gel with hydrophilic groups such as hydroxyl, sulfonic acid, carboxyl, amino, ether, etc., or combinations thereof.

[0017] Furthermore, the electrolytic hydrogen production module includes an electrolyzer and an electrolyte temperature controller; the electrolyzer is connected to the electrolyte temperature controller.

[0018] As a preferred option, the electrolyte circulation and regeneration module is designed to achieve a "liquid-gas-liquid" phase transition migration process. It utilizes a hygroscopic medium to directly replenish pure water into the electrolyte solution, including a two-stage energy-free mass transfer device. The two-stage energy-free mass transfer device is a device that uses a waterproof and breathable layer to divide the space into an electrolyte chamber and a hygroscopic medium chamber, or any mass transfer device that can achieve two-phase or multi-phase liquid isolation but allows gas passage. Alternatively, it can be selected from commercially mature flat-sheet membrane distillation reaction mass transfer devices, hollow fiber membrane distillation reaction mass transfer devices, or falling film absorption towers, etc., with similar structures, only the substances filled in them are replaced with electrolytes and hygroscopic media, respectively.

[0019] In a further preferred embodiment, the electrolyte circulation and regeneration module includes a heat exchanger, a filter, a secondary energy-free mass transfer device, an electrolyte circulation pump, and an electrolyte check valve; the electrolytic cell of the electrolytic hydrogen production module is connected to the heat exchanger, and the heat exchanger is connected to the filter and then to the secondary energy-free mass transfer device; the secondary energy-free mass transfer device is connected to the electrolyte temperature controller in the electrolytic hydrogen production module through the electrolyte circulation pump and the electrolyte check valve, and the electrolyte temperature controller is connected to the electrolytic cell.

[0020] Preferably, the waterproof and breathable layer is a commercially mature waterproof and breathable layer, or is selected from any one of porous TPU film, PDMS, PTFE film, or a porous waterproof and breathable mass transfer layer prepared by spraying, screen printing or electrostatic adsorption process of graphene, PVDF particles or PTFE particles.

[0021] Preferably, the water vapor self-capture module is a module for realizing the "gas-liquid" phase change migration process, used to directly obtain moisture from the air, including a primary energy-saving mass transfer device and a moisture-absorbing medium circulation pump; the primary energy-saving mass transfer device is a container that allows the moisture-absorbing medium to convect or contact with the air, or a device for gas-liquid phase mass transfer, such as a spray tower, plate tower, falling film tower, spray tower, absorption tower, bubble tower, or similar structure, only the filling material is replaced with a moisture-absorbing medium; the moisture-absorbing medium absorbs moisture from the air in the primary energy-saving mass transfer device, and further replenishes the electrolyte with moisture in the secondary energy-saving mass transfer device of the electrolyte circulation regeneration module.

[0022] In a further preferred embodiment, the water vapor self-capture module includes a primary energy-free mass transfer device, a moisture-absorbing medium circulation pump, and a moisture-absorbing medium check valve; the primary energy-free mass transfer device is connected to the moisture-absorbing medium chamber in the electrolyte circulation and regeneration module through the moisture-absorbing medium circulation pump and the moisture-absorbing medium check valve.

[0023] Preferably, the hygroscopic medium used in the hygroscopic medium chambers of both the primary and secondary energy-free mass transfer devices can be glycerol, CaSO4 solution, MgSO4 solution, LiBr solution, CaCl2 solution, CsF solution, or LiCl solution, etc. The electrolyte filled in the electrolyte chamber of the secondary energy-free mass transfer device is the same as the electrolyte in the electrolytic cell.

[0024] Preferably, the system also includes a hydrogen collection module and an oxygen collection module; wherein the hydrogen collection module includes a hydrogen separator, a hydrogen scrubber, a hydrogen cooler, and a hydrogen storage tank; the oxygen collection module includes an oxygen separator, an oxygen scrubber, an oxygen cooler, and an oxygen storage tank; both the hydrogen separator and the oxygen separator are connected to the electrolyzer, and the hydrogen scrubber, hydrogen cooler, and hydrogen storage tank are connected in sequence after the hydrogen separator; the oxygen scrubber, oxygen cooler, and oxygen storage tank are connected in sequence after the oxygen separator.

[0025] Preferably, the system also includes a cooling module, which includes a radiator, a cooling water tank, and a cooling water pump. The cooling water tank is connected to the radiator and is connected to a hydrogen separator, a hydrogen scrubber, a hydrogen cooler, an oxygen separator, an oxygen scrubber, an oxygen cooler, and a heat exchanger via the cooling water pump to provide cooling water and keep the system in a cooling environment.

[0026] Preferably, a temperature controller is coupled before the primary energy-saving mass transfer device to control the temperature of the hygroscopic medium, thereby adjusting the interfacial vapor pressure of the hygroscopic medium in the primary energy-saving mass transfer device and achieving a better effect in absorbing moisture from the air; a temperature controller is coupled before the secondary energy-saving mass transfer device to adjust the interfacial vapor pressure of the hygroscopic medium in the secondary energy-saving mass transfer device by controlling the temperature of the hygroscopic medium, so as to achieve better secondary migration mass transfer effect and controllable adjustment.

[0027] Furthermore, the electrolyte pumped out of the electrolyzer, as well as the electrolyte collected in the hydrogen separator, oxygen separator, hydrogen scrubber, and oxygen scrubber, enters the secondary energy-free mass transfer device after passing through a heat exchanger and filter. When the electrolyte and the hygroscopic medium flow in close contact with the waterproof and breathable layer, the interfacial water vapor pressure difference between them causes the hygroscopic medium to undergo a phase change and vaporization. The generated water vapor enters the electrolyte side through the waterproof and breathable layer and, under the action of the interfacial pressure difference, induces the water vapor to liquefy and undergo a secondary phase change. In addition, the waterproof and breathable layer effectively prevents the electrolyte and the hygroscopic medium from mutually penetrating and contaminating each other. This process continuously replenishes the electrolyte with pure water for electrolysis. Electrolysis consumes water at the same time to maintain the interfacial water vapor pressure difference between the electrolyte and the hygroscopic medium in the secondary energy-free mass transfer device, and the interfacial water vapor pressure difference between the hygroscopic medium and the air in the primary energy-free mass transfer device, thereby inducing a continuous replenishment of water to the electrolyte. After moisture is transferred to the electrolyte, the hygroscopic medium circulates to the water vapor capture module. This module, consisting of a primary energy-saving mass transfer unit, a hygroscopic medium circulation pump, and a check valve, is one of the most crucial parts of the entire system. In the primary energy-saving mass transfer unit, the hygroscopic medium further absorbs moisture from the air, preparing for the next cycle of moisture transfer to the electrolyte in the secondary energy-saving mass transfer unit.

[0028] A system for direct air electrolysis to produce hydrogen includes a power supply module, an electrolyzer, a hydrogen separator, a hydrogen scrubber, a hydrogen regulating valve, a hydrogen check valve, a hydrogen cooler, a hydrogen storage tank, an oxygen separator, an oxygen scrubber, an oxygen regulating valve, an oxygen check valve, an oxygen cooler, an oxygen storage tank, a radiator, a cooling water tank, a cooling water pump, a heat exchanger, a filter, a two-stage energy-free mass transfer device, an electrolyte circulation pump, an electrolyte check valve, an electrolyte temperature controller, a hygroscopic medium check valve, and a hygroscopic medium circulation pump. The system consists of a primary energy-saving mass transfer device; the secondary energy-saving mass transfer device is divided into an electrolyte mass transfer chamber and a hygroscopic medium mass transfer chamber by a waterproof and breathable layer separating a sealed space. The primary energy-saving mass transfer device is a container that allows convection or contact between the hygroscopic medium and air, or a device for gas-liquid phase mass transfer, such as a spray tower, plate tower, falling film tower, spray tower, absorption tower, bubble tower, or similar structure, where the filling material is replaced with a hygroscopic medium. The power supply module is connected to the anode and cathode of the electrolytic cell to provide electrical energy. A hydrogen separator is installed on the cathode side of the electrolytic cell, followed by a hydrogen scrubber, a hydrogen regulating valve, a hydrogen check valve, a hydrogen cooler, and a hydrogen storage tank in sequence. An oxygen separator is installed on the anode side of the electrolytic cell, followed by an oxygen scrubber, an oxygen regulating valve, an oxygen check valve, an oxygen cooler, and an oxygen storage tank in sequence. The electrolytic cell, hydrogen separator, and oxygen separator are all connected to a heat exchanger. The heat exchanger is connected to a filter and then to a secondary energy-free mass transfer device. The secondary energy-free mass transfer device is connected to… The electrolyte circulation pump and electrolyte check valve are connected to the electrolyte temperature controller, which is connected to the electrolytic cell. The primary energy-saving mass transfer device is filled with a hygroscopic medium, which undergoes mass transfer with the air to absorb moisture from the air. It is then circulated to the secondary energy-saving mass transfer device through the hygroscopic medium circulation pump, the hygroscopic medium check valve, and corresponding pipelines. The cooling water tank is connected to the hydrogen separator, hydrogen scrubber, hydrogen cooler, oxygen separator, oxygen scrubber, oxygen cooler, and heat exchanger via a cooling water pump.

[0029] Preferably, each module in this system is connected to a control system for automated control processes.

[0030] A process for producing hydrogen through direct air electrolysis includes the following steps:

[0031] Moisture in the air is transferred to the hygroscopic medium in the first-stage energy-free mass transfer device of the water vapor self-capture module. The hygroscopic medium, having acquired moisture, further transfers moisture to the electrolyte side in the second-stage energy-free mass transfer device of the electrolyte circulation and regeneration module. The electrolyte, now containing pure moisture, undergoes electrolytic hydrogen production in the electrolyzer, consuming the moisture. The simultaneous consumption of moisture during electrolysis further maintains the interfacial pressure difference between the electrolyte and the hygroscopic medium, and between the hygroscopic medium and the air, thereby further driving the hygroscopic medium to acquire moisture from the air and replenish the electrolyte. In this process, when the electrolysis rate = the first-stage mass transfer rate = the second-stage mass transfer rate, a continuous direct air electrolysis hydrogen production process will be achieved.

[0032] Preferably, the above-described process for direct air electrolysis to produce hydrogen includes the following specific steps:

[0033] The power supply module provides electricity to the electrolysis hydrogen production module;

[0034] First, the electrolyte is introduced into the cathode, anode, or both electrodes of the electrolytic cell simultaneously, causing a redox reaction to generate hydrogen and oxygen. If the electrolytic cell is alkaline or AEM, the electrolyte first undergoes a reduction reaction at the cathode, producing OH-. - The electrolyte enters the anode through a diaphragm or anion exchange membrane and undergoes an oxidation reaction to produce oxygen. If the electrolytic cell is a PEM electrolytic cell, the electrolyte undergoes an oxidation-oxygen evolution reaction at the anode to produce H₂. + It enters the cathode through the proton exchange membrane and undergoes a reduction reaction to produce hydrogen gas;

[0035] The generated hydrogen and oxygen enter the hydrogen separator and oxygen separator respectively. This process separates the generated hydrogen and oxygen from the entrained electrolytes or water. The separated hydrogen and oxygen then enter the hydrogen scrubber and oxygen scrubber respectively. This process further cleans the gas of any remaining electrolytes and water.

[0036] After cleaning, the hydrogen enters the hydrogen cooler to dry and cool under the control of the hydrogen regulating valve and the check valve, and is then stored in the hydrogen storage tank; after cleaning, the oxygen enters the oxygen cooler to dry and cool under the control of the oxygen regulating valve and the check valve, and is then stored in the hydrogen storage tank.

[0037] The electrolyte after reaction in the electrolytic cell, as well as the electrolyte separated and recovered from the hydrogen separator, hydrogen scrubber, oxygen separator, and oxygen scrubber, all pass through a heat exchanger and have any impurities removed in a filter. The purified electrolyte then enters the electrolyte chamber of the secondary energy-free mass transfer device, while a hygroscopic medium is continuously introduced into the hygroscopic medium chamber. The two chambers are separated by a waterproof and breathable layer, allowing only water vapor to pass through and preventing liquid water from penetrating and contaminating each other. At this time, when the electrolyte and the hygroscopic medium pass through the secondary energy-free mass transfer device simultaneously, under the action of the interfacial pressure difference, the hygroscopic medium undergoes vaporization on the surface of the waterproof and breathable layer to generate water vapor. The water vapor enters the electrolyte side through the waterproof and breathable layer and, under the action of the interfacial pressure difference, induces a phase change of water vapor to liquefy and replenish the electrolyte with moisture.

[0038] After being replenished with water, the electrolyte enters the temperature controller through the electrolyte circulation pump and check valve. After being adjusted to the optimal electrolysis temperature, it is circulated back into the electrolytic cell to carry out the electrolytic hydrogen production reaction.

[0039] After the moisture in the hygroscopic medium is transferred to the electrolyte, the hygroscopic medium is circulated to the first-stage energy-free mass transfer device in the water vapor self-capture module. Under the action of the interfacial pressure difference between the air and the hygroscopic medium, it absorbs the moisture in the air, preparing for the replenishment of moisture to the electrolyte in the next cycle.

[0040] Preferably, in this system, moisture in the air is transferred to the hygroscopic medium in the first-stage energy-free mass transfer unit of the water vapor capture module (first-stage mass transfer). The hygroscopic medium, having acquired moisture, further transfers the moisture to the electrolyte side in the second-stage energy-free mass transfer unit of the electrolyte circulation and regeneration module (second-stage mass transfer). The electrolyte, now containing purified moisture, undergoes electrolysis in the electrolyzer to produce hydrogen, consuming the moisture. This water consumption during electrolysis further maintains the interfacial pressure difference between the electrolyte and the hygroscopic medium, and between the hygroscopic medium and the air, thereby further driving the hygroscopic medium to absorb moisture from the air and replenish the electrolyte. This process establishes a new thermodynamic equilibrium. When the electrolysis rate, the first-stage mass transfer rate, and the second-stage mass transfer rate are equal, the entire system is in equilibrium, enabling continuous and stable direct hydrogen production from air. Furthermore, the system can dynamically adjust the rates of the first and second-stage mass transfers by regulating the vapor pressure caused by the concentration of the hygroscopic medium and the electrolyte themselves, thus matching different air humidity environments.

[0041] The system described above can directly electrolyze hydrogen from air, and the energy consumption of electrolysis will be comparable to that of industrial electrolysis of pure water to produce hydrogen. There is no need for additional energy consumption for desalination / purification of non-pure water solutions, nor is there any additional energy consumption for capturing moisture from the air.

[0042] Compared with the prior art, the positive effects of the present invention are reflected in:

[0043] (i) The system can realize the direct electrolysis of air to produce hydrogen, and the energy consumption of electrolysis is comparable to that of industrial electrolysis of pure water, without the need for additional energy consumption for desalination / purification and capturing moisture in the air.

[0044] (II) In this system, moisture in the air is transferred to the hygroscopic medium in the first-stage energy-free mass transfer device of the water vapor self-capture module (first-stage mass transfer). The hygroscopic medium, having acquired moisture, further transfers the moisture to the electrolyte side in the second-stage energy-free mass transfer device of the electrolyte circulation and regeneration module (second-stage mass transfer). The electrolyte, now containing pure moisture, undergoes electrolysis in the electrolyzer to produce hydrogen, consuming the moisture. This water consumption during electrolysis, in turn, further maintains the interfacial pressure difference between the electrolyte and the hygroscopic medium, and between the hygroscopic medium and the air, thereby further driving the hygroscopic medium to acquire moisture from the air and replenish the electrolyte. This process establishes a new thermodynamic equilibrium. When the electrolysis rate, the first-stage mass transfer rate, and the second-stage mass transfer rate are equal, the entire system is in equilibrium, enabling continuous and stable direct hydrogen production from air.

[0045] (iii) The system can further dynamically adjust the rate of primary and secondary mass transfer by the vapor pressure change caused by its own concentration change, thereby matching different air humidity environments.

[0046] (iv) This system avoids the limitations of time and space on the principle and technology of hydrogen production from air, avoids the competition of impurities in the system for oxygen evolution reaction, avoids the bottleneck of catalyst deactivation caused by impurity ions, and avoids the problems of toxicity and corrosiveness caused by side reactions.

[0047] (v) The system collects hydrogen and oxygen independently, and can collect high-purity hydrogen and oxygen at the same time.

[0048] (vi) The system can achieve a continuous and stable air hydrogen production process that is energy-efficient, free from water collection and time and space limitations; in addition, it can achieve energy conversion and stable storage of unstable renewable energy, providing technical means for the construction of future distributed energy systems.

[0049] (vii) This technology is expected to realize a nationwide and distributed hydrogen energy pattern and accelerate the construction of integrated hydrogen production and refueling. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the structure of an air direct electrolysis hydrogen production system according to the present invention;

[0051] Figure 1Markings and corresponding component names: 1—Power supply module; 2—Electrolyzer; 3—Hydrogen separator; 4—Hydrogen scrubber; 5—Hydrogen regulating valve; 6—Hydrogen check valve; 7—Hydrogen cooler; 8—Hydrogen storage tank; 9—Oxygen separator; 10—Oxygen scrubber; 11—Oxygen regulating valve; 12—Oxygen check valve; 13—Oxygen cooler; 14—Oxygen storage tank; 15—Radiator; 16—Cooling water tank; 17—Cooling water pump; 18—Heat exchanger; 19—Filter; 20—Secondary energy-saving mass transfer device; 21—Electrolyte circulation pump; 22—Electrolyte check valve; 23—Electrolyte temperature controller; 24—Moisture-absorbing medium check valve; 25—Moisture-absorbing medium circulation pump; 26—First-stage energy-saving mass transfer device; A—Electrolyte chamber; B—Moisture-absorbing medium chamber.

[0052] Figure 2 This is a test graph showing the stability of hydrogen production via direct air electrolysis in Example 1;

[0053] Figure 3 This is a test graph showing the stability of hydrogen production via direct air electrolysis in Example 2;

[0054] Figure 4 This is a test graph showing the stability of hydrogen production via direct air electrolysis in Example 3;

[0055] Figure 5 This is a test graph showing the stability of hydrogen production via direct air electrolysis in Example 4; Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. However, this should not be construed as limiting the scope of the invention to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practice in the art without departing from the above-described technical concept of this invention should be included within the scope of this invention.

[0057] Example 1:

[0058] like Figure 1 As shown, an air direct electrolysis hydrogen production system includes an energy supply module, an electrolysis hydrogen production module, an electrolyte recycling and regeneration module, and a water vapor self-capture module, wherein:

[0059] The power supply module is connected to the electrolysis hydrogen production module and is used to provide electrical energy for the hydrogen production reaction; in this embodiment, the power supply module is a commercial power supply.

[0060] Electrolytic hydrogen production module, which includes an electrolytic cell. The electrolytic cell uses a self-made alkaline electrolytic cell (composed of 5 electrolytic units connected in parallel, each electrolytic unit including a cathode and an anode separated by a diaphragm, the anode being a foamed nickel-molybdenum, the cathode being nickel-plated platinum, and the diaphragm being a polysulfone porous membrane). After the electrolyte is introduced into the electrolytic cell, an oxidation-reduction reaction occurs, consuming water and producing hydrogen and oxygen.

[0061] The electrolyte circulation and regeneration module is used to replenish pure water from the hygroscopic medium to the electrolyte, and is connected to the electrolytic hydrogen production module and the water vapor self-capture module respectively.

[0062] The water vapor capture module is used to absorb moisture from the air, providing a continuous source of moisture for hydrogen production via electrolysis.

[0063] The electrolyte circulation and regeneration module is a module for realizing the "liquid-gas-liquid" phase change migration process. It uses a hygroscopic medium to directly replenish pure water into the electrolyte solution, including a two-stage energy-free mass transfer device. The two-stage energy-free mass transfer device is a device that uses a waterproof and breathable layer to divide the space into an electrolyte chamber and a hygroscopic medium chamber.

[0064] The water vapor self-capture module is a module for realizing the "gas-liquid" phase change migration process and is used to directly obtain moisture from the air. It includes a primary energy-free mass transfer device and a moisture-absorbing medium circulation pump. The primary energy-free mass transfer device is an open container that allows the moisture-absorbing medium to convect or contact with the air. In this embodiment, an ordinary open container is used, only the filling material is replaced with a moisture-absorbing medium.

[0065] The electrolyte pumped from the electrolyzer enters the secondary energy-free mass transfer unit. When the electrolyte and the hygroscopic medium flow closely against the waterproof and breathable layer, the interfacial water vapor pressure difference causes the hygroscopic medium to undergo a phase change and vaporize. The resulting water vapor enters the electrolyte side through the waterproof and breathable layer and, under the influence of the interfacial pressure difference, induces liquefaction and a secondary phase change. Furthermore, the waterproof and breathable layer effectively prevents cross-contamination between the electrolyte and the hygroscopic medium. This process continuously replenishes the electrolyte with pure water for electrolysis. Electrolysis simultaneously consumes water to maintain the interfacial water vapor pressure difference between the electrolyte and the hygroscopic medium in the secondary energy-free mass transfer unit, and between the hygroscopic medium and air in the primary energy-free mass transfer unit, thereby inducing a continuous replenishment of water to the electrolyte. After the water is transferred to the electrolyte, the hygroscopic medium circulates to the water vapor self-capture module. This module, consisting of the primary energy-free mass transfer unit, the hygroscopic medium circulation pump, and a check valve, is one of the most crucial components of the entire system. The hygroscopic medium further absorbs moisture from the air in the first-stage energy-free mass transfer device, preparing for the transfer of moisture to the electrolyte in the second-stage energy-free mass transfer device in the next cycle.

[0066] Specific operation: A PTFE porous waterproof and breathable membrane was used as the waterproof and breathable layer in the secondary energy-free mass transfer device, with an effective mass transfer area of ​​2m².2 45wt% potassium hydroxide solution was used as the electrolyte; 30wt% LiBr solution was used as the hygroscopic medium; the primary energy-free mass transfer device was an open container with an effective surface area of ​​4m² with air. 2 .like Figure 2 The device operates in ambient air (average temperature 25°C, average humidity 70%), with both the lithium bromide solution and electrolyte solution at room temperature, at a current of 250 mA / cm². 2 Under these conditions, the battery stack operated stably for 72 hours, with an actual voltage of approximately 2.2V.

[0067] Example 2:

[0068] A system for direct air electrolysis to produce hydrogen includes a power supply module, an electrolyzer, a hydrogen separator, a hydrogen scrubber, a hydrogen regulating valve, a hydrogen check valve, a hydrogen cooler, a hydrogen storage tank, an oxygen separator, an oxygen scrubber, an oxygen regulating valve, an oxygen check valve, an oxygen cooler, an oxygen storage tank, a radiator, a cooling water tank, a cooling water pump, a heat exchanger, a filter, a secondary energy-saving mass transfer device, an electrolyte circulation pump, an electrolyte check valve, an electrolyte temperature controller, a hygroscopic medium check valve, a hygroscopic medium circulation pump, and a primary energy-saving mass transfer device. The secondary energy-saving mass transfer device is divided into an electrolyte mass transfer chamber and a hygroscopic medium chamber by a waterproof and breathable layer. The primary energy-saving mass transfer device is a container that facilitates mass transfer between the hygroscopic medium and air. The power supply module is connected to the anode and cathode of the electrolyzer to provide electrical energy. A hydrogen separator is installed on the cathode side of the electrolyzer, and a hydrogen scrubber and a hydrogen storage tank are sequentially installed after the hydrogen separator. The system includes a regulating valve, a hydrogen check valve, a hydrogen cooler, and a hydrogen storage tank. An oxygen separator is installed on the anode side of the electrolyzer, followed by an oxygen scrubber, an oxygen regulating valve, an oxygen check valve, an oxygen cooler, and an oxygen storage tank. The electrolyzer, hydrogen separator, and oxygen separator are all connected to a heat exchanger. The heat exchanger is connected to a filter and then to a secondary energy-saving mass transfer device. The secondary energy-saving mass transfer device is connected to an electrolyte temperature controller via an electrolyte circulation pump and an electrolyte check valve. The electrolyte temperature controller is connected to the electrolyzer. The primary energy-saving mass transfer device is filled with a hygroscopic medium. This hygroscopic medium undergoes mass transfer with the air, absorbing moisture from the air. It is circulated to the secondary energy-saving mass transfer device via a hygroscopic medium circulation pump, a hygroscopic medium check valve, and corresponding pipelines. A cooling water tank is connected to the hydrogen separator, hydrogen scrubber, hydrogen cooler, oxygen separator, oxygen scrubber, oxygen cooler, and heat exchanger via a cooling water pump.

[0069] Each module in this system is connected to the control system for automating control processes.

[0070] The electrolyte pumped from the electrolyzer, as well as the electrolyte collected in the hydrogen separator, oxygen separator, hydrogen scrubber, and oxygen scrubber, enters the secondary energy-free mass transfer device after passing through a heat exchanger and filter. When the electrolyte and the hygroscopic medium flow in close contact with the waterproof and breathable layer, the interfacial water vapor pressure difference between them causes the hygroscopic medium to undergo a phase change and vaporization. The generated water vapor enters the electrolyte side through the waterproof and breathable layer and, under the action of the interfacial pressure difference, induces the water vapor to liquefy and undergo a secondary phase change. In addition, the waterproof and breathable layer effectively prevents the electrolyte and the hygroscopic medium from interpenetrating and contaminating each other. This process continuously replenishes the electrolyte with pure water for electrolysis. Electrolysis consumes water to maintain the interfacial water vapor pressure difference between the electrolyte and the hygroscopic medium in the secondary energy-free mass transfer device, and the interfacial water vapor pressure difference between the hygroscopic medium and the air in the primary energy-free mass transfer device, thereby inducing a continuous replenishment of water to the electrolyte. After moisture is transferred to the electrolyte, the hygroscopic medium circulates to the water vapor capture module. This module, consisting of a primary energy-saving mass transfer unit, a hygroscopic medium circulation pump, and a check valve, is one of the most crucial parts of the entire system. In the primary energy-saving mass transfer unit, the hygroscopic medium further absorbs moisture from the air, preparing for the next cycle of moisture transfer to the electrolyte in the secondary energy-saving mass transfer unit.

[0071] A process for producing hydrogen through direct air electrolysis includes the following steps:

[0072] The power supply module provides electricity to the electrolysis hydrogen production module;

[0073] First, the electrolyte is introduced into the cathode, anode, or both electrodes of the electrolytic cell, where a redox reaction occurs to generate hydrogen and oxygen. If the electrolytic cell is alkaline or AEM, the electrolyte first undergoes a reduction reaction at the cathode, producing OH-. - The electrolyte enters the anode through a diaphragm or anion exchange membrane and undergoes an oxidation reaction to produce oxygen. If the electrolytic cell is a PEM electrolytic cell, the electrolyte undergoes an oxidation-oxygen evolution reaction at the anode to produce H₂. + It enters the cathode through the proton exchange membrane and undergoes a reduction reaction to produce hydrogen gas;

[0074] The generated hydrogen and oxygen enter the hydrogen separator and oxygen separator respectively. This process separates the generated hydrogen and oxygen from the entrained electrolytes or water. The separated hydrogen and oxygen then enter the hydrogen scrubber and oxygen scrubber respectively. This process further cleans the gas of any remaining electrolytes and water.

[0075] After cleaning, the hydrogen enters the hydrogen cooler to dry and cool under the control of the hydrogen regulating valve and the check valve, and is then stored in the hydrogen storage tank; after cleaning, the oxygen enters the oxygen cooler to dry and cool under the control of the oxygen regulating valve and the check valve, and is then stored in the hydrogen storage tank.

[0076] The electrolyte after reaction in the electrolytic cell, as well as the electrolyte separated and recovered from the hydrogen separator, hydrogen scrubber, oxygen separator, and oxygen scrubber, all pass through a heat exchanger and have any impurities removed in a filter. The purified electrolyte then enters the electrolyte chamber of the secondary energy-free mass transfer device, while a hygroscopic medium is continuously introduced into the hygroscopic medium chamber. The two chambers are separated by a waterproof and breathable layer, allowing only water vapor to pass through and preventing liquid water from penetrating and contaminating each other. At this time, when the electrolyte and the hygroscopic medium pass through the secondary energy-free mass transfer device simultaneously, under the action of the interfacial pressure difference, the hygroscopic medium undergoes vaporization on the surface of the waterproof and breathable layer to generate water vapor. The water vapor enters the electrolyte side through the waterproof and breathable layer and, under the action of the interfacial pressure difference, induces a phase change of water vapor to liquefy and replenish the electrolyte with moisture.

[0077] After being replenished with water, the electrolyte enters the temperature controller through the electrolyte circulation pump and check valve. After being adjusted to the optimal electrolysis temperature, it is circulated back into the electrolytic cell to carry out the electrolytic hydrogen production reaction.

[0078] After the moisture in the hygroscopic medium is transferred to the electrolyte, the hygroscopic medium is circulated to the first-stage energy-free mass transfer device in the water vapor capture module. Under the action of the interfacial pressure difference between the air and the hygroscopic medium, it absorbs the moisture in the air, preparing for the replenishment of moisture to the electrolyte in the next cycle.

[0079] In this system, moisture in the air is transferred to the hygroscopic medium in the primary energy-free mass transfer unit of the water vapor self-capture module (primary mass transfer). The hygroscopic medium, having acquired moisture, further transfers the moisture to the electrolyte side in the secondary energy-free mass transfer unit of the electrolyte circulation and regeneration module (secondary mass transfer). The electrolyte, now containing purified moisture, undergoes electrolysis in the electrolyzer to produce hydrogen, consuming the moisture. This water consumption during electrolysis maintains the interfacial pressure difference between the electrolyte and the hygroscopic medium, and between the hygroscopic medium and the air, thereby further driving the hygroscopic medium to absorb moisture from the air and replenish the electrolyte. This process establishes a new thermodynamic equilibrium. When the electrolysis rate, the primary mass transfer rate, and the secondary mass transfer rate are equal, the entire system is in equilibrium, enabling continuous and stable direct hydrogen production from air. Furthermore, the system can dynamically adjust the rates of primary and secondary mass transfer based on the vapor pressure changes caused by variations in its own concentration, thus adapting to different air humidity environments.

[0080] Specific operation: A PTFE porous waterproof and breathable membrane was used as the waterproof and breathable layer in the secondary energy-free mass transfer device, with an effective mass transfer area of ​​2m². 2 A 50wt% potassium hydroxide solution was used as the electrolyte; a 30wt% lithium chloride solution was used as the hygroscopic medium; the primary energy-free mass transfer device was an open container with an effective surface area of ​​4m² with air. 2 .like Figure 3The device was tested in ambient air in Chengdu (average temperature 25℃, average humidity 65%), with both the lithium chloride solution and electrolyte solution at room temperature, at a current of 250 mA / cm². 2 Under these conditions, the battery stack operated stably for 280 hours, with an actual voltage of approximately 2.2V and an electrolysis energy consumption of approximately 5.29 kWh / Nm³. 3 H2 is produced at a rate of approximately 175 L / h.

[0081] Other embodiments of the system follow the same method steps as in Embodiment 2, with differences shown in Table 1:

[0082]

[0083]

[0084]

[0085] Example 3:

[0086] A direct air electrolysis hydrogen production system, with the same structure as in Example 2, differs in that: a commercial alkaline electrolyzer is used; and a PTFE porous waterproof and breathable membrane is employed as the waterproof and breathable layer in the secondary energy-free mass transfer device, with an effective mass transfer area of ​​2m². 2 A 50wt% potassium hydroxide solution was used as the electrolyte; a 30wt% lithium chloride solution was used as the hygroscopic medium; the primary energy-free mass transfer device was an open container with an effective surface area of ​​4m² with air. 2 .like Figure 4 The apparatus was operated at an average temperature of 25°C and an average humidity of 65%, with both the lithium chloride solution and the electrolyte solution at room temperature, and at a current of 250 mA / cm². 2 Under these conditions, the battery stack operated stably for 100 hours, with an actual voltage of approximately 2.1V.

[0087] Other embodiments of the system follow the same method steps as in embodiment 3, with differences shown in Table 2:

[0088]

[0089]

[0090]

[0091] Example 4:

[0092] A direct air electrolysis hydrogen production system, with the same structure as in Example 2, differs in that: a commercial alkaline electrolyzer is used; and a PTFE porous waterproof and breathable membrane is employed as the waterproof and breathable layer in the secondary energy-free mass transfer device, with an effective mass transfer area of ​​2m². 2A 50wt% potassium hydroxide solution was used as the electrolyte; a 30wt% lithium chloride solution was used as the hygroscopic medium; the primary energy-free mass transfer device was an open container with an effective surface area of ​​4m² with air. 2 .like Figure 5 The apparatus was operated at an average temperature of 25°C and an average humidity of 65%. The lithium chloride solution in the first-stage energy-free mass transfer unit was at room temperature, the lithium chloride solution in the second-stage energy-free mass transfer unit was at 50°C, and the KOH solution in the second-stage energy-free mass transfer unit was at 60°C, at a current of 250 mA / cm². 2 Under these conditions, the battery stack operated stably for 100 hours, with an actual voltage of approximately 1.82V.

[0093] Other embodiments of the system follow the same method steps as in embodiment 4, with differences shown in Table 3:

[0094]

[0095]

[0096]

[0097] As can be seen from the above embodiments, the system will realize the direct electrolysis of air to produce hydrogen, and the energy consumption of electrolysis will be comparable to that of industrial electrolysis of pure water to produce hydrogen. There is no need for additional energy consumption for desalination / purification of non-pure water solutions, nor is there any additional energy consumption for capturing moisture from the air.

[0098] 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.

[0099] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Based on the technical essence of the present invention, any simple modifications, equivalent substitutions, and improvements made to the above embodiments within the spirit and principles of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A direct air electrolysis hydrogen production system, characterized in that... The system includes a power supply module, an electrolysis hydrogen production module, an electrolyte recycling and regeneration module, and a water vapor self-capture module, wherein: The power supply module is connected to the electrolysis hydrogen production module; An electrolytic hydrogen production module, which includes an electrolytic cell, through which hydrogen and oxygen are produced after an electrolyte is introduced; The electrolyte recycling module is connected to the electrolytic hydrogen production module and the water vapor self-capture module, respectively. The water vapor capture module is used to absorb moisture from the air, providing a continuous source of moisture for electrolytic hydrogen production; The electrolyte circulation and regeneration module includes a two-stage energy-free mass transfer device. This module is designed to realize the "liquid-gas-liquid" phase change migration process, using a hygroscopic medium to directly replenish pure water into the electrolyte solution. The two-stage energy-free mass transfer device is a device that uses a waterproof and breathable layer to divide the space into an electrolyte chamber and a hygroscopic medium chamber. When the electrolyte and the hygroscopic medium flow in close contact with the waterproof and breathable layer, the water vapor pressure difference at the interface between the two causes the hygroscopic medium to undergo a phase change and vaporization. The generated water vapor enters the electrolyte side through the waterproof and breathable layer and is induced to liquefy under the action of the interface pressure difference, resulting in a secondary phase change. The water vapor self-capture module includes a primary energy-free mass transfer device and a moisture-absorbing medium circulation pump; this module is designed to realize the "gas-liquid" phase change migration process and is used to directly extract moisture from the air without water collection energy consumption. The hygroscopic medium absorbs moisture from the air in the primary energy-free mass transfer unit and further replenishes the electrolyte with moisture in the secondary energy-free mass transfer unit of the electrolyte circulation and regeneration module.

2. The air direct electrolysis hydrogen production system as described in claim 1, characterized in that: The energy source for the power supply module is electricity converted from traditional coal power or renewable energy.

3. The air direct electrolysis hydrogen production system as described in claim 1, characterized in that: The electrolytic cell is any one of alkaline electrolytic cells, PEM electrolytic cells, and AEM electrolytic cells, or a combination of any one of these electrolytic cells connected in series or in parallel.

4. The air direct electrolysis hydrogen production system as described in claim 1, characterized in that: A primary energy-free mass transfer device is a container that allows for convection or contact mass transfer between a hygroscopic medium and air, or a device used for gas-liquid phase mass transfer.

5. The air direct electrolysis hydrogen production system as described in claim 1, characterized in that: The waterproof and breathable layer is selected from any one of porous TPU membrane, PDMS, or PTFE membrane.

6. The air direct electrolysis hydrogen production system as described in claim 1, characterized in that: The waterproof and breathable layer is a porous waterproof and breathable mass transfer layer made of graphene, PVDF particles, and PTFE particles through spraying, screen printing, or electrostatic adsorption processes.

7. The air direct electrolysis hydrogen production system as described in claim 1, characterized in that: The electrolyte filled in the electrolytic cell is either a liquid electrolyte or a solid gel electrolyte; the liquid electrolyte is a liquid with a low saturated water vapor pressure or with the function of absorbing water vapor; the solid gel electrolyte is a substance that can induce water vapor to undergo phase change and liquefy.

8. The air direct electrolysis hydrogen production system according to any one of claims 1-7, characterized in that: The system also includes a hydrogen collection module and an oxygen collection module; the hydrogen collection module includes a hydrogen separator, a hydrogen scrubber, a hydrogen cooler, and a hydrogen storage tank; the oxygen collection module includes an oxygen separator, an oxygen scrubber, an oxygen cooler, and an oxygen storage tank; both the hydrogen separator and the oxygen separator are connected to the electrolyzer, and the hydrogen scrubber, hydrogen cooler, and hydrogen storage tank are connected in sequence after the hydrogen separator; the oxygen scrubber, oxygen cooler, and oxygen storage tank are connected in sequence after the oxygen separator.

9. The air direct electrolysis hydrogen production system as described in claim 8, characterized in that: The system also includes a cooling module, which comprises a radiator, a cooling water tank, and a cooling water pump. The cooling water tank is connected to the radiator and, via the cooling water pump, to a hydrogen separator, a hydrogen scrubber, a hydrogen cooler, an oxygen separator, an oxygen scrubber, an oxygen cooler, and a heat exchanger to provide cooling water.

10. The air direct electrolysis hydrogen production system as described in claim 9, characterized in that: The electrolyte pumped out of the electrolytic cell, as well as the electrolyte collected in the hydrogen separator, oxygen separator, hydrogen scrubber, and oxygen scrubber, enter the secondary energy-free mass transfer device after passing through a heat exchanger and a filter.

11. The air direct electrolysis hydrogen production system as described in claim 9 or 10, characterized in that: A temperature controller is coupled before the first-stage energy-free mass transfer device to achieve temperature control of the hygroscopic medium, thereby adjusting the interfacial vapor pressure of the hygroscopic medium in the first-stage energy-free mass transfer device and achieving a better effect of absorbing moisture from the air. A temperature controller is coupled before the secondary energy-free mass transfer device. By controlling the temperature of the hygroscopic medium, the interfacial vapor pressure of the hygroscopic medium in the secondary energy-free mass transfer device is adjusted to achieve better secondary migration mass transfer effect and controllable adjustment.

12. The air direct electrolysis hydrogen production system as described in claim 11, characterized in that: Each module in this system is connected to the control system for automating control processes.

13. A process for direct air electrolysis to produce hydrogen using the system described in any one of claims 1-12, characterized in that... Includes the following steps: Moisture in the air is transferred to the hygroscopic medium in the first-stage energy-free mass transfer device of the water vapor self-capture module. The hygroscopic medium, having acquired moisture, further transfers the moisture to the electrolyte side in the second-stage energy-free mass transfer device of the electrolyte circulation and regeneration module. The electrolyte, now containing pure moisture, undergoes electrolysis to produce hydrogen in the electrolyzer, consuming the moisture. Electrolysis simultaneously consumes moisture, further maintaining the interfacial pressure difference between the electrolyte and the hygroscopic medium, and between the hygroscopic medium and the air, thereby further driving the hygroscopic medium to acquire moisture from the air and replenish the electrolyte. In this process, when the electrolysis rate = the first-stage mass transfer rate = the second-stage mass transfer rate, a continuous and stable direct air electrolysis hydrogen production process will be achieved.

14. The process for direct air electrolysis to produce hydrogen as described in claim 13, characterized in that... Includes the following steps: The power supply module provides electricity to the electrolysis hydrogen production module; First, the electrolyte is introduced into the electrolytic cell to generate hydrogen and oxygen through redox reaction; if the electrolytic cell is an alkaline electrolytic cell or an AEM electrolytic cell, the electrolyte first undergoes a reduction hydrogen evolution reaction at the cathode to produce OH - passes through the diaphragm or anion exchange membrane into the anode and undergoes an oxidation reaction to produce oxygen; if the electrolytic cell is a PEM electrolytic cell, the electrolyte first undergoes an oxidation oxygen evolution reaction at the anode to produce H + passes through the proton exchange membrane into the cathode and undergoes a reduction reaction to produce hydrogen; The generated hydrogen and oxygen enter the hydrogen separator and oxygen separator respectively. This process separates the generated hydrogen and oxygen from the entrained electrolytes or water. The separated hydrogen and oxygen then enter the hydrogen scrubber and oxygen scrubber respectively. This process further cleans the gas of any remaining electrolytes and water. After cleaning, the hydrogen enters the hydrogen cooler to dry and cool under the control of the hydrogen regulating valve and the check valve, and is then stored in the hydrogen storage tank; after cleaning, the oxygen enters the oxygen cooler to dry and cool under the control of the oxygen regulating valve and the check valve, and is then stored in the oxygen storage tank. The electrolyte after reaction in the electrolytic cell, as well as the electrolyte separated and recovered from the hydrogen separator, hydrogen scrubber, oxygen separator, and oxygen scrubber, all pass through a heat exchanger and have any impurities removed in a filter. The purified electrolyte then enters the electrolyte chamber of the secondary energy-free mass transfer device, while a hygroscopic medium is continuously introduced into the hygroscopic medium chamber. The two chambers are separated by a waterproof and breathable layer, allowing only water vapor to pass through and preventing liquid water from penetrating and contaminating each other. At this time, when the electrolyte and the hygroscopic medium pass through the secondary energy-free mass transfer device simultaneously, under the action of the interfacial pressure difference, the hygroscopic medium undergoes vaporization on the surface of the waterproof and breathable layer to generate water vapor. The water vapor enters the electrolyte side through the waterproof and breathable layer and, under the action of the interfacial pressure difference, induces a phase change of water vapor to liquefy and replenish the electrolyte with moisture. After being replenished with water, the electrolyte enters the temperature controller through the electrolyte circulation pump and check valve. After being adjusted to the optimal electrolysis temperature, it is circulated back into the electrolytic cell to carry out the electrolytic hydrogen production reaction. After the moisture in the hygroscopic medium is transferred to the electrolyte, the hygroscopic medium is circulated to the first-stage energy-free mass transfer device in the water vapor self-capture module. Under the action of the interfacial pressure difference between the air and the hygroscopic medium, it absorbs the moisture in the air, preparing for the replenishment of moisture to the electrolyte in the next cycle.

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