Magnetic field assisted anionic membrane electrolysis hydrogen production device and hydrogen production method

Abstract

The invention discloses a magnetic field assisted anionic membrane electrolysis hydrogen production device and a hydrogen production method. The magnetic field assisted anion membrane electrolysis hydrogen production device comprises an anion exchange membrane, an anode for oxygen evolution reaction, a cathode for hydrogen evolution reaction and an end plate, and the cathode and the anode are both made of magnetic nickel-grade catalysts; two sides of the anion exchange membrane are respectively assembled with the cathode and the anode to form a gas diffusion layer and a membrane electrode; two end plates are arranged on the two sides of the membrane electrode respectively, and two permanent magnets are arranged on the outer sides of the two end plates in parallel and apply magnetic fields to the cathode and the anode respectively. According to the method, a mature magnetic nickel-grade catalyst and an anion exchange membrane are respectively used as a working electrode and a diaphragm, and a magnetic field is applied under the condition of high current density, so that on one hand, the nucleation and desorption rate of bubbles under the condition that charged gas accelerates the high current density under the action of Lorentz force is optimized; on the other hand, the spin polarization of the magnetic nickel-based catalyst is optimized, so that the energy conversion efficiency is improved, and the hydrogen production energy consumption is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of electrolytic hydrogen production, in particular to a magnetic field assisted anion membrane electrolytic hydrogen production device and a hydrogen production method. Background Art

[0002] The anion membrane electrolysis hydrogen production (AEM) system has the advantages of high efficiency, sustainability, low cost and pollution-free. It integrates the low-cost advantages of alkaline electrolysis (ALK) hydrogen production and the compact structure and low resistance advantages of proton membrane electrolysis (PEM), and is gradually becoming a new generation of electrolysis hydrogen production equipment.

[0003] However, the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode in the AEM electrolysis hydrogen production system involve the evolution of hydrogen (H2) and oxygen (O2). The three-electrode system involves a complex gas-liquid-solid three-phase system. The desorption ability of bubbles at high current density is the key to affecting mass transfer and system resistance. In addition, the nickel-based catalyst in the AEM electrolysis hydrogen production is limited by the OER reaction kinetics, thus becoming a bottleneck limiting the energy of water decomposition.

[0004] Based on the two core problems of HER hydrogen bubbles being difficult to desorb from the electrode surface and OER kinetics being slow, the existing technology usually adopts some micro-nanostructure hydrophilicity design optimization, material regulation of catalyst active sites, or application of some external energy fields to increase mass transfer and reaction efficiency. For example, patent CN115058735A synthesized a binary metal catalyst of Co-P / Ni / NF through ultrasound, electrodeposition, constant current treatment and other steps, and applied a magnetic field at -0.15V vs .RHE, up to 100mA.cm -2 The patent CN 220550237U designs a magnetic field-loaded hydrogen evolution electrode device; the patent CN112575336 improves the performance of OER through the surface magnetic field. Although many studies are currently committed to optimizing HER or OER through magnetic fields in order to promote hydrogen production by electrolysis. However, existing studies mostly focus on the synthesis of magnetic materials, or because the mechanism of the influence of magnetic fields is unclear, only one-sided HER or OER is optimized, and the current density does not reach the industrial high current level under the complex mechanical system, and it has not been possible to achieve the optimization of the cathode and anode at the same time based on the AEM electrolyzer.

[0005] Therefore, how to simply, efficiently and cost-effectively optimize the performance of the anode and cathode of AEM to improve the performance of the entire AEM electrolyzer is a bottleneck problem that plagues researchers. Summary of the invention

[0006] In order to optimize the AEM reaction system efficiently and at low cost, the present invention provides a magnetic field-assisted anion membrane electrolysis hydrogen production device and a hydrogen production method, which simultaneously optimize the cathode HER and the anode OER, respectively using a mature magnetic nickel-grade catalyst and an anion exchange membrane as a catalyst and a diaphragm, and by applying an external magnetic field, on the one hand, optimizing the charged gas under the Lorentz force to accelerate the nucleation and desorption rate of bubbles at high current density, and on the other hand, optimizing the spin polarization of the magnetic nickel-based catalyst, thereby improving the energy conversion efficiency and reducing the energy consumption of hydrogen production.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions.

[0008] In a first aspect, the present invention provides a magnetic field-assisted anion membrane electrolysis hydrogen production device, which comprises an anion exchange membrane, an anode for oxygen evolution reaction, a cathode for hydrogen evolution reaction and an end plate, wherein the cathode and anode materials are both magnetic nickel-grade catalysts; The two sides of the anion exchange membrane are respectively assembled with the cathode and the anode to form a gas diffusion layer and a membrane electrode; two end plates are respectively placed on both sides of the membrane electrode, and two permanent magnets are arranged in parallel outside the two end plates to apply magnetic fields to the cathode and the anode respectively.

[0009] The electrolysis of water is affected by the polarization of the cathode and anode, and includes a complex gas-liquid-solid three-phase mass transfer process. Therefore, improving the reaction kinetics of hydrogen evolution at the cathode and oxygen evolution at the anode and accelerating the mass transfer process play an important role in improving the energy efficiency of the reaction.

[0010] The magnetic field-assisted anion membrane electrolysis hydrogen production device of the present invention can simultaneously optimize the cathode HER and the anode OER. The present invention uses mature magnetic nickel-grade catalysts and anion exchange membranes as working electrodes and diaphragms, respectively, and applies a magnetic field under high current density. On the one hand, the charged gas is optimized under the action of the Lorentz force to accelerate the nucleation and desorption rate of bubbles under high current density, and on the other hand, the spin polarization of the magnetic nickel-based catalyst is optimized, thereby improving the energy conversion efficiency and reducing the energy consumption of hydrogen production.

[0011] Furthermore, the anode material and cathode material are both nickel-iron based magnetic materials, such as Raney nickel.

[0012] Furthermore, an S-shaped flow channel is provided on the end plate.

[0013] In a second aspect, the present invention provides a method for producing hydrogen by magnetic field-assisted anion membrane electrolysis, which uses the above-mentioned magnetic field-assisted anion membrane electrolysis hydrogen production device, and comprises: Step 1, using two sheets of Raney nickel as cathode and anode, and assembling them with anion exchange membrane to form a gas diffusion layer and membrane electrode; Step 2, first add gaskets to both sides of the assembled gas diffusion layer and membrane electrode, then add stainless steel end plates, assemble and fix them with bolts and nuts to form a three-electrode electrochemical system to obtain an anion membrane electrolyzer; Step 3: The assembled anion membrane electrolyzer is connected to the external electrolyte through a peristaltic pump, and the circulating electrolyte is introduced; and two permanent magnets are arranged in parallel on the outside of the two end plates, at ≥200mA / cm 2 A magnetic field is applied to the cathode at a current density of ≥400 mA / cm 2 A magnetic field is applied to the anode at a current density of .

[0014] Furthermore, the electrode size in step 1 is preferably (0.9-1.1)*(0.9-1.1)cm.

[0015] Furthermore, the magnetic field strength in step 3 is preferably 250-350 mT.

[0016] Furthermore, when producing hydrogen in step 3, a cyclic voltammetry scan is performed on the three-electrode electrochemical system, and the scan rate is preferably 9-11 mV / s.

[0017] Furthermore, in step 3, the voltage range during hydrogen evolution is preferably 0.0V to -0.6V. vs .RHE, the voltage range for oxygen evolution is preferably 1.2V to 1.8V vs .RHE.

[0018] Furthermore, the electrolyte in step 3 is preferably 55-65° C., 0.9-1.1 M KOH.

[0019] Furthermore, in step 3, the flow rate of the electrolyte is preferably 9-11 mL / min.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention optimizes both HER and OER performance: The present invention can provide a non-contact bubble nucleation and diffusion control method by applying an external magnetic field through a permanent magnet, without the need for external energy input. Under the joint regulation of viscosity, buoyancy, surface tension, and Lorentz force (magnetic field conditions), the bubbles optimize the aspect ratio, merging process, and rising rate of bubble nucleation, thereby increasing the mass transfer efficiency of HER and reducing the ohmic impedance. In addition, based on the transition metal magnetic nickel-based catalytic electrode, the intrinsic magnetic field of the metal ions is regulated by an external magnetic field. eg The occupied state regulates the bonding strength between the metal ion and the oxygen intermediate. The regulation of spin-polarized electrons is achieved through the action of the magnetic field. The spin-polarized exchange interaction dominates the generation of triplet O2 molecules and optimizes the OER kinetics.

[0021] 2. The structure of the present invention is simple and easy to implement, and is suitable for large-scale industrial production: only commercial low-cost magnetic Raney nickel catalyst is used as the cathode / anode material, and there are no cumbersome material synthesis steps such as pretreatment and post-treatment. The raw materials of the catalyst used are abundant in reserves and low in cost; and the magnetic field is provided only by permanent magnets to apply the magnetic field, and no external energy supply is required. The device is suitable for large-scale industrial production.

[0022] 3. The present invention achieves an ampere-level current density: compared with the currently reported magnetic optimization system which has a current density of only mA level, the present invention achieves an A-level current density. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below in combination with the accompanying drawings and detailed embodiments. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative labor. Figure 1 is a schematic diagram of a three-electrode system of the present invention; Figure 2 This is a HER performance diagram of the present invention under the action of a magnetic field; Figure 3 This is a diagram of the OER performance under the action of a magnetic field of the present invention; Figure 4 It is a structural diagram of the magnetic field assisted anion membrane electrolysis hydrogen production device of the present invention; Figure 5 It is a comparison diagram of electrochemical polarization curves of a conventional AEM electrolysis device (Comparative Example 1) and a magnetically enhanced AEM electrolysis device (Example 1); Figure 1 In the figure, 1-working electrode, 2-reference electrode, 3-counter electrode, 4-diaphragm, 5-magnet.

[0024] Figure 4 In the figure, 4-diaphragm, 5-magnet, 6-anode flow channel plate, 7-gasket, 8-anode electrode, 9-cathode electrode, 10-cathode flow channel plate. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be described clearly and completely below in conjunction with the drawings of the specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The nickel-based electrodes and anion exchange membranes used in the following examples are commercial catalysts and membranes.

[0027] Part I: Construction of an electrochemical system with magnetic enhancement for HER and OER like Figure 1 As shown, a three-electrode system was constructed to evaluate the effects of the magnetic field on hydrogen evolution and oxygen evolution reactions, respectively.

[0028] Step 1: If Figure 1 A three-electrode system was constructed as shown, with Pt sheet (1*1cm), Hg / HgO electrode, and commercial Raney nickel electrode as counter electrode, working electrode, and working electrode, respectively. 60℃, 1M KOH was used as the electrolyte.

[0029] Step 2: Enhance HER performance by applying a magnetic field. Using commercial Raney nickel as the working electrode, a three-electrode test was performed using a Chenhua electrochemical workstation in the voltage range of 0.0V to -0.6V. vs .RHE, the performance of HER in magnetic field and non-magnetic field was evaluated by linear sweep saturation (LSV) at a scan rate of 10mV / s.

[0030] Step 3: Enhance OER performance by applying a magnetic field. Using commercial Raney nickel as the working electrode, a three-electrode test was performed using a Chenhua electrochemical workstation in the voltage range of 1.2V to 1.8V. vs .RHE, the performance of HER in magnetic field and non-magnetic field was evaluated by linear sweep saturation (LSV) at a scan rate of 10mV / s.

[0031] like Figure 2 As shown in the figure, the HER hydrogen evolution performance is significantly improved under the action of the magnetic field. As the applied voltage increases, the difference in current density becomes larger and larger. At a voltage of -0.5V vs. RHE, the current density increases by 50%. From the observation of the reaction phenomenon, the charged hydrogen is affected by the Lorentz force when moving in the magnetic field. The magnetohydrodynamic convection caused by the Lorentz force promotes the circulation of the cathode electrolyte, accelerates the desorption of the cathode H2 bubbles, and accelerates the cathode mass transfer, thereby increasing the hydrogen evolution current density.

[0032] like Figure 3 As shown in the figure, the OER oxygen evolution performance is slightly improved under the action of a magnetic field at a high current density. This is because at the same current density, the amount of oxygen evolution bubbles is twice the amount of hydrogen evolution bubbles, and the phenomenon of increased mass transfer is not very obvious, but it shows that the magnetic field has a certain regulation on the spin-polarized electrons of ferromagnetic materials, thereby increasing the OER reaction kinetics.

[0033] Part 2: Assembly of the AEM unit Comparative Example 1: Assembly of a conventional AEM electrolysis device The steps include: Step 1: Use two commercial Raney nickel catalysts as cathode and anode, with a size of 1*1cm, and then assemble them with the AEM membrane to form the gas diffusion layer and membrane electrode; Step 2: After adding gaskets to both sides of the gas diffusion layer and membrane electrode assembled in step 1 above, add stainless steel end plates on both sides and assemble and fix them with bolts and nuts; Step 3: Connect the AEM electrolytic cell assembled in step 2 to the external 1M KOH electrolyte (60°C) via a peristaltic pump and introduce the circulating electrolyte.

[0034] Example 1 Assembly of magnetically enhanced AEM electrolysis device The steps include: Step 1: Use two commercial nickel-iron-based catalysts as cathode and anode, with a size of 1*1cm, and then assemble them with AEM membrane (i.e. anion exchange membrane, referred to as diaphragm) to form a gas diffusion layer and membrane electrode; Step 2: After adding gaskets to both sides of the gas diffusion layer and membrane electrode assembled in step 1 above, add stainless steel end plates (i.e., anode flow channel plate and cathode flow channel plate) on both sides, and assemble and fix them with bolts and nuts; Step 3: Add permanent magnets (300mT) in parallel to the cathode end plate and the anode end plate to enhance the magnetic field. Figure 3 As shown; Step 4: Connect the AEM electrolytic cell assembled in step 3 to the external 1M KOH electrolyte (60°C) via a peristaltic pump and introduce the circulating electrolyte.

[0035] The assembled magnetic field assisted anion membrane electrolysis hydrogen production device is as follows Figure 4 As shown, it includes an anion exchange membrane, an anode for oxygen evolution reaction, a cathode for hydrogen evolution reaction and an end plate, wherein the cathode and anode materials are both magnetic nickel-grade catalysts; the two sides of the anion exchange membrane are respectively assembled with the cathode and the anode to form a gas diffusion layer and a membrane electrode; two end plates are respectively placed on both sides of the membrane electrode, and two permanent magnets are arranged in parallel on the outer sides of the two end plates.

[0036] Part III Performance Evaluation of AEM Devices 1. Performance test evaluation method The AEM electrolysis devices assembled in Comparative Example 1 and Example 1 were respectively connected to the cathode and anode of an electrochemical workstation CHI1140C workstation, and the electrochemical linear polarization curves of Comparative Example 1 and Example 1 were respectively obtained by linear scanning (LSV).

[0037] 2. Analysis and Conclusion Figure 5The electrochemical polarization curves of the conventional AEM electrolysis device (Comparative Example 1) and the magnetically enhanced AEM electrolysis device (Example 1) are shown. The data show that at a battery voltage of 1.8 V, the polarization current of Comparative Example 1 is approximately 100 mA / cm 2 In comparison, when the polarization voltage of Example 1 was 1.8 V, the current density increased by 20%, which improved the electrolysis energy efficiency and reduced the electrolysis energy consumption.

[0038] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A magnetic field assisted anion membrane electrolysis hydrogen production device, characterized in that: It includes an anion exchange membrane, an anode for oxygen evolution reaction, a cathode for hydrogen evolution reaction and an end plate, wherein the cathode and anode materials are both magnetic nickel-grade catalysts; The two sides of the anion exchange membrane are respectively assembled with the cathode and the anode to form a gas diffusion layer and a membrane electrode; two end plates are respectively placed on both sides of the membrane electrode, and two permanent magnets are arranged in parallel outside the two end plates to apply magnetic fields to the cathode and the anode respectively.

2. The magnetic field-assisted anion membrane electrolysis hydrogen production device according to claim 1, characterized in that: The anode material and cathode material are both nickel-iron based magnetic materials.

3. The magnetic field-assisted anion membrane electrolysis hydrogen production device according to claim 1, characterized in that: The end plate is provided with an S-shaped flow channel.

4. A method for producing hydrogen by magnetic field-assisted anion membrane electrolysis, which uses the magnetic field-assisted anion membrane electrolysis hydrogen production device according to any one of claims 1 to 3, characterized in that: include: Step 1, using two sheets of Raney nickel as cathode and anode, and assembling them with anion exchange membrane to form a gas diffusion layer and membrane electrode; Step 2, first add gaskets to both sides of the assembled gas diffusion layer and membrane electrode, then add stainless steel end plates, assemble and fix them with bolts and nuts to form a three-electrode electrochemical system to obtain an anion membrane electrolyzer; Step 3, the assembled anion membrane electrolyzer is connected to an external electrolyte via a peristaltic pump, and a circulating electrolyte is introduced; Two permanent magnets are placed in parallel on the outside of the two end plates, with a current of ≥200mA / cm 2 A magnetic field is applied to the cathode at a current density of ≥400 mA / cm 2 A magnetic field is applied to the anode at a current density of .

5. The method for producing hydrogen by magnetic field-assisted anion membrane electrolysis according to claim 4, characterized in that: The electrode size in step 1 is (0.9-1.1)*(0.9-1.1)cm.

6. The method for producing hydrogen by magnetic field-assisted anion membrane electrolysis according to claim 4, characterized in that: The magnetic field strength in step 3 is 250-350 mT.

7. The method for producing hydrogen by magnetic field-assisted anion membrane electrolysis according to claim 4, characterized in that: During hydrogen production in step 3, a cyclic voltammetry scan is performed on the three-electrode electrochemical system at a scan rate of 9-11 mV / s.

8. The method for producing hydrogen by magnetic field-assisted anion membrane electrolysis according to claim 7, characterized in that: In step 3, the voltage range of the cathode hydrogen evolution reaction is 0.0V to -0.6V vs .RHE, the voltage range of the anode oxygen evolution reaction is 1.2V to 1.8V vs .RHE.

9. The method for producing hydrogen by magnetic field-assisted anion membrane electrolysis according to claim 4, characterized in that: The electrolyte in step 3 is 55-65° C., 0.9-1.1 M KOH.

10. The method for producing hydrogen by magnetic field-assisted anion membrane electrolysis according to claim 9, characterized in that: The flow rate of the electrolyte in step 3 is 9-11 mL / min.

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