Water electrolysis apparatus and water electrolysis method

Abstract

To effectively prevent a decrease in hydrogen production efficiency during water electrolysis using an electrolyte containing magnetic fluid. [Solution] A water electrolysis apparatus comprising: a pair of electrodes, each extending in a predetermined direction and arranged to contact an electrolyte containing a magnetic fluid; a magnetic field applying means for applying a magnetic field to at least one of the electrodes from one end; and an ion-permeable partition wall provided between an anode region where the anode electrode is located and a cathode region where the cathode electrode is located, wherein in the anode region, the anode electrode is brought into contact with an electrolyte containing a magnetic fluid to which a cationic surfactant has been added, and in the cathode region, the cathode electrode is brought into contact with an electrolyte containing a magnetic fluid to which an anionic surfactant has been added.

Description

Technical Field

[0001] The present disclosure relates to a water electrolysis apparatus and a water electrolysis method for producing hydrogen from water.

Background Art

[0002] As a water electrolysis apparatus, there is known a configuration in which a pair of electrodes disposed in an electrolytic solution are separated by a partition wall through which hydroxide ions can permeate (see Patent Document 1). In this apparatus, it is important to remove hydrogen bubbles adhering to the electrode surface so that the contact area between the electrode surface and the electrolytic solution does not decrease in order to maintain the hydrogen production efficiency.

[0003] As a configuration for removing bubbles from the electrode surface, there has been proposed a configuration in which a magnetic fluid is contained in the electrolytic solution and a magnetic field gradient that decreases as it moves away from the electrode surface is generated, and non-magnetic bubbles are removed from the electrode surface by magnetic buoyancy according to this magnetic field gradient (see Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above configuration, there is a case where magnetic particles in the magnetic fluid aggregate and adhere to the electrode surface, and as a result of the magnetic particles reducing the contact area between the electrolytic solution and the electrode surface, the hydrogen production efficiency decreases over time.

[0006] This disclosure was made to solve these problems, and its purpose is to effectively prevent a decrease in hydrogen production efficiency when using an electrolyte containing magnetic fluid for water electrolysis. [Means for solving the problem]

[0007] To solve the above problems, the first-phase water electrolysis apparatus comprises a pair of electrodes, each extending in a predetermined direction and arranged to contact an electrolyte containing a magnetic fluid; a magnetic field application means for applying a magnetic field to at least one of the electrodes from one end; and an ion-permeable partition wall provided between an anode region where the anode electrode is located and a cathode region where the cathode electrode is located, wherein in the anode region, the anode electrode is brought into contact with an electrolyte containing a magnetic fluid to which a cationic surfactant has been added, and in the cathode region, the cathode electrode is brought into contact with an electrolyte containing a magnetic fluid to which an anionic surfactant has been added.

[0008] To solve the above problems, the water electrolysis method of the second phase is a water electrolysis apparatus comprising: a pair of electrodes each extending in a predetermined direction and arranged to contact an electrolyte containing a magnetic fluid; a magnetic field application means for applying a magnetic field to at least one of the electrodes from one end; and an ion-permeable partition wall provided between an anode region where the anode electrode is located and a cathode region where the cathode electrode is located, wherein in the anode region, the anode electrode is brought into contact with an electrolyte containing a magnetic fluid to which a cationic surfactant has been added, while in the cathode region, the cathode electrode is brought into contact with an electrolyte containing a magnetic fluid to which an anionic surfactant has been added.

[0009] First, regardless of whether the magnetic fluid is contained in an electrolyte for water electrolysis or not, it is common practice to form a layer of ionic surfactant on the surface of each magnetic particle to impart polarity, and to maintain the dispersed state through the repulsive force between the magnetic particles.

[0010] Magnetic particles that have been given polarity in this way tend to lose their polarity when they react with ions generated during the water electrolysis process. This weakens the repulsive force between the magnetic particles, causing them to condense, and potentially adhere to the electrode surface.

[0011] The reaction of magnetic particles with ions is thought to be due to the polarity of the electrodes being opposite to the polarity of the ionic surfactant in the electrolyte; therefore, matching these two polarities is effective in suppressing the reaction between magnetic particles and ions.

[0012] In this regard, in each of the above-mentioned phases, the reaction between magnetic particles and ions can be suppressed by matching the polarity of the electrodes with the polarity of the surfactant added to the magnetic fluid containing the electrolyte (anode / cationic, cathode / anionic). This is because a magnetic field gradient is generated that decreases with distance from the electrode surface, and each non-magnetic bubble is more easily removed from the electrode surface due to the influence of magnetic buoyancy corresponding to this magnetic field gradient. As a result, it is possible to effectively prevent a decrease in the efficiency of hydrogen production during water electrolysis. [Brief explanation of the drawing]

[0013] [Figure 1] Conceptual diagram showing the configuration of a water electrolysis apparatus according to an embodiment of this disclosure. [Figure 2] Conceptual diagram showing magnetic particles in a magnetic fluid, which is an embodiment of the present disclosure. [Figure 3] Enlarged view of the main part showing the water electrolysis process using a water electrolysis apparatus according to the present disclosure embodiment. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described below with reference to the drawings. (1) Overall structure

[0015] As shown in Figure 1, the water electrolysis apparatus 1 comprises an electrolytic cell 10 containing an electrolyte solution containing magnetic fluid, a pair of electrodes 20 extending in predetermined directions, a magnetic field application means 30 for applying a magnetic field from at least one end of one of the electrodes 20, a partition wall 40 dividing the electrolytic cell 10, and a power supply 50 for applying voltage to the pair of electrodes 20.

[0016] The electrolytic cell 10 comprises an anode region 11 where the electrode 20 on the anode 21 side is located, and a cathode region 13 where the electrode 20 on the cathode 23 side is located.

[0017] Each electrode 20 extends in a predetermined direction and is positioned to contact the electrolyte containing magnetic fluid. In this embodiment, the electrodes 20 are arranged in the electrolytic cell 10 in the region containing the electrolyte, spaced apart from each other, and each extends from top to bottom.

[0018] The magnetic field application means 30 is a magnet positioned below the electrode 20, on the outside of the electrolytic cell 10, and straddling its bottom, and is magnetized in the vertical direction. In this embodiment, magnets are positioned below the anode 21 and the cathode 23, respectively. As a result, the magnetic field application means 30 is configured to apply a magnetic field to each of the electrodes 20 from below.

[0019] The partition wall 40 is provided as a wall that separates the anode region 11 and the cathode region 13 of the electrolytic cell 10, and is made of an ion-permeable material. In this embodiment, the partition wall 40 is made of a material that is permeable to hydroxide ions (OH-).

[0020] Among these, the anode region 11 contains an electrolytic solution 110 containing a magnetic fluid to which a cationic surfactant, which is a kind of ionic surfactant, is added. On the other hand, the cathode region 13 contains an electrolytic solution 130 containing a magnetic fluid to which an anionic surfactant, which is also a kind of ionic surfactant, is added. Thus, in the electrolytic cell 10, in the anode region 11, the anode 21 is brought into contact with the electrolytic solution containing the magnetic fluid to which the cationic surfactant is added, while in the cathode region 13, the cathode 23 is brought into contact with the electrolytic solution containing the magnetic fluid to which the anionic surfactant is added.

[0021] Note that, as the electrolytic solution of the present embodiment, neutral salts such as sodium sulfate and potassium nitrate are adopted as materials that are neutral and have high electrical conductivity.

[0022] In addition, the magnetic fluid contained in the electrolytic solution is a fluid in which magnetic particles and an ionic surfactant are dispersed in a water-based dispersion medium. As shown in FIG. 2, the magnetic fluid forms layers 113 and 133 of the ionic surfactant on the surfaces of the magnetic particles 111 in the magnetic fluid contained in the electrolytic solution 110 and the magnetic particles 131 in the magnetic fluid contained in the electrolytic solution 130, respectively, to impart polarity, so that the repulsive force between the magnetic particles 111 or the magnetic particles 131 maintains the dispersed state.

[0023] (2) Modified Example As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments at all, and it is needless to say that the present invention can take various forms as long as it belongs to the technical scope of the present invention.

[0024] For example, in the above embodiment, the configuration in which the magnetic field applying means 30 is a magnet is illustrated. However, as the magnetic field applying means 30, an electromagnet capable of controlling the magnitude of the non-uniform magnetic field according to the magnitude of the current passed therethrough may be adopted.

[0025] Furthermore, in the above embodiment, a configuration was illustrated in which the magnetic field applying means 30 is located below the anode 21 and the cathode 23, respectively. However, the magnetic field applying means 30 may be located on at least one of the electrodes 20.

[0026] Furthermore, in the above embodiment, a configuration was illustrated in which the partition wall 40 is formed of a material that is permeable to hydroxide ions (OH-). However, the partition wall 40 may be formed of a material that is permeable to at least one of hydrogen ions (H+) and hydroxide ions (OH-).

[0027] (3) Action, effect In the water electrolysis apparatus 1 of the above embodiment, water electrolysis is performed by applying a voltage between the electrodes 20 while the anode region 11 contains an electrolyte 110 containing a magnetic fluid to which a cationic surfactant has been added, and the cathode region 13 contains an electrolyte 130 containing a magnetic fluid to which an anionic surfactant has been added.

[0028] During this water electrolysis process, ions are generated around each electrode 20 (see equations (1) and (2) in Figure 1; 4H+ and 2OH-). The magnetic particles in the magnetic fluid contained in the electrolyte easily lose their polarity when they react with these generated ions, which weakens the repulsive force between the magnetic particles, causing them to condense and potentially adhere to the surface of the electrode 20.

[0029] The magnetic particles react with ions because, in regions 11 and 13 containing the electrolyte, the polarity of the electrodes is opposite to the polarity of the ionic surfactant in the electrolyte. Therefore, matching these two polarities is effective in suppressing the reaction between magnetic particles and ions.

[0030] In this regard, in the above embodiment, by matching the polarity of the electrode 20 in the regions 11 and 13 containing the electrolyte with the polarity of the surfactant added to the magnetic fluid containing the electrolyte (anode 21 / cationic, cathode 23 / anionic), the reaction between magnetic particles and ions can be suppressed.

[0031] This is because, as shown in Figure 3, a magnetic field gradient is generated that decreases with distance from the electrode 20 surface, and each non-magnetic bubble 150 is more easily removed from the electrode 20 surface due to the influence of magnetic buoyancy Fm corresponding to this magnetic field gradient. A force F (=Fg+Fb+Fm), which is the resultant of gravity Fg, buoyancy Fb, and magnetic buoyancy Fm, acts on each bubble 150.

[0032] Thus, the water electrolysis apparatus 1 of the above embodiment can effectively prevent a decrease in hydrogen production efficiency during water electrolysis. [Explanation of Symbols]

[0033] 1...Water electrolysis device, 10...Electrolytic cell, 11...Anode region, 13...Cathode region, 20...Electrode, 21...Anode, 23...Cathode, 30...Magnetic field application means, 40...Partition wall, 50...Power supply, 110...Electrolyte, 111...Magnetic particles, 113...Layer, 133...Layer, 130...Electrolyte, 150...Bubbles.

Claims

1. A pair of electrodes, each extending in a predetermined direction and positioned to contact an electrolyte containing magnetic fluid, A magnetic field applying means for applying a magnetic field to at least one of the electrodes from one end, The device comprises an ion-permeable partition wall provided between the anode region where the anode-side electrode is located and the cathode region where the cathode-side electrode is located, In the anode region, the electrode on the anode side is brought into contact with an electrolyte containing a magnetic fluid to which a cationic surfactant has been added, while in the cathode region, the electrode on the cathode side is brought into contact with an electrolyte containing a magnetic fluid to which anionic surfactant has been added. Water electrolysis equipment.

2. The system comprises an electrolytic cell containing an electrolyte solution that includes magnetic fluid, Each of the electrodes is arranged in the electrolytic cell in a manner that extends from top to bottom with a gap between them in the region where the electrolyte is contained. The magnetic field applying means applies a magnetic field from below to at least one of the electrodes, The anode region contains an electrolyte containing a magnetic fluid to which a cationic surfactant has been added, while the cathode region contains an electrolyte containing a magnetic fluid to which an anionic surfactant has been added. The water electrolysis apparatus according to claim 1.

3. The partition wall has permeability to at least one of hydrogen ions and hydroxide ions. A water electrolysis apparatus according to claim 1 or claim 2.

4. A pair of electrodes, each extending in a predetermined direction and positioned to contact an electrolyte containing magnetic fluid, A magnetic field applying means for applying a magnetic field to at least one of the electrodes from one end, A water electrolysis apparatus comprising an ion-permeable partition wall provided between an anode region where the anode-side electrode is located and a cathode region where the cathode-side electrode is located, In the anode region, the electrode on the anode side is brought into contact with an electrolyte containing a magnetic fluid to which a cationic surfactant has been added, while in the cathode region, the electrode on the cathode side is brought into contact with an electrolyte containing a magnetic fluid to which anionic surfactant has been added. Water electrolysis method.

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