Determination method, quality assurance method, and determination device

Abstract

To provide a determination method capable of checking whether or not a target molecule is hydrogen generated by water electrolysis or a molecule generated by using the hydrogen as a raw material, a quality assurance method, and a determination device.SOLUTION: In a determination method, when a deuterium presence ratio relative to light hydrogen of a target molecule is equal to or less than a predetermined threshold value that is smaller than the deuterium presence ratio relative to light hydrogen in nature, the target molecule is determined to be an electrolytic hydrogen-containing molecule.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a determination method, a quality assurance method, and a determination device. [Background technology]

[0002] Carbon dioxide is considered a problem as a cause of global warming, and there has been an active movement worldwide to curb carbon dioxide emissions. Hydrogen does not emit carbon dioxide when used and can be obtained by electrolyzing water using renewable energy, so it has attracted attention as an alternative fuel to fossil fuels. An alkaline water electrolysis device, disclosed in Patent Document 1, is known as a method for producing hydrogen by electrolyzing water. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 181662 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, hydrogen has been produced industrially by steam reforming fossil fuels such as natural gas. However, there is no way to confirm that hydrogen has been produced by water electrolysis. In addition, ammonia is expected to be a next-generation fuel, and hydrocarbons are used as raw materials for various chemical products. These molecules can be produced using hydrogen as a raw material, but, like hydrogen, there is no way to confirm that they have been produced by water electrolysis. If it were possible to confirm whether these molecules were produced via water electrolysis, the quality of these molecules could be guaranteed.

[0005] Therefore, an object of the present disclosure is to provide a determination method, a quality assurance method, and a determination device that can determine whether a target molecule is hydrogen produced by water electrolysis or a molecule produced using the hydrogen as a raw material. [Means for solving the problem]

[0006] The present disclosure provides a method for determining whether a target molecule containing hydrogen is an electrolytic hydrogen-containing molecule, which includes a molecule produced using hydrogen molecules produced by water electrolysis as a raw material. The method determines that the target molecule is an electrolytic hydrogen-containing molecule if the abundance ratio of deuterium to protons in the target molecule is equal to or less than a predetermined threshold value that is lower than the abundance ratio of deuterium to protons in nature.

[0007] The molecule of interest may be ammonia or a hydrocarbon.

[0008] The quality assurance method according to the present disclosure is a quality assurance method for assuring that a target molecule containing hydrogen is an electrolytic hydrogen-containing molecule, which includes a molecule produced using hydrogen molecules produced by water electrolysis as a raw material. The quality assurance method assures that the target molecule is an electrolytic hydrogen-containing molecule if the abundance ratio of deuterium to protons in the target molecule is equal to or less than a predetermined threshold value that is lower than the abundance ratio of deuterium to protons in nature.

[0009] The determination device includes a determination unit that determines whether a target molecule containing hydrogen is an electrolytic hydrogen-containing molecule, which includes a molecule produced using hydrogen molecules produced by water electrolysis as a raw material. The determination unit determines that the target molecule is an electrolytic hydrogen-containing molecule when the abundance ratio of deuterium to protons in the target molecule is equal to or less than a predetermined threshold that is lower than the abundance ratio of deuterium to protons in nature.

[0010] The determination device may include a measurement unit that measures the abundance ratio of deuterium to proton in the target molecule. The determination device may also include a determination unit that determines that the target molecule is an electrolytic hydrogen-containing molecule when the abundance ratio of deuterium to proton in the target molecule obtained by the measurement unit is equal to or less than a predetermined threshold that is lower than the abundance ratio of deuterium to proton in nature. The determination device may also include an output unit that outputs the determination result determined by the determination unit. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a determination method, a quality assurance method, and a determination device that can determine whether a target molecule is hydrogen generated by water electrolysis or a molecule generated using the hydrogen as a raw material. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing an example of a low-temperature water electrolysis apparatus according to this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an example of a PEM water electrolysis device. [Figure 3] FIG. 3 is a schematic diagram illustrating an example of an alkaline water electrolysis apparatus. [Figure 4] FIG. 4 is a schematic diagram illustrating an example of an AEM water electrolysis apparatus. [Figure 5] FIG. 5 is a schematic diagram showing an example of a medium- to high-temperature steam electrolysis device according to this embodiment. [Figure 6] FIG. 6 is a schematic diagram showing an example of an SOEC water electrolysis device. [Figure 7] FIG. 7 is a schematic diagram showing an example of a PCEC water electrolysis device. [Figure 8] FIG. 8 is a schematic diagram showing an example of an electrolysis device equipped with a permeation device. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, several exemplary embodiments will be described with reference to the drawings. Note that the dimensional proportions of the drawings are exaggerated for the convenience of explanation and may differ from the actual proportions.

[0014] The determination method according to this embodiment determines whether a target molecule is an electrolytic hydrogen-containing molecule. Electrolytic hydrogen-containing molecules include hydrogen molecules produced by water electrolysis or molecules produced using the hydrogen molecules as a raw material. Water electrolysis can be performed using renewable energy. If the target molecule is an electrolytic hydrogen-containing molecule and water is electrolyzed using renewable energy, it can be determined whether the target molecule is derived from renewable energy.

[0015] The target molecule is a molecule containing hydrogen. The target molecule may be hydrogen molecules, ammonia, or hydrocarbons. Similarly, the electrolytic hydrogen-containing molecule may be hydrogen molecules, ammonia, or hydrocarbons. Hydrogen and ammonia can be used as carbon-free fuels. Therefore, hydrogen and ammonia can be used as fuels derived from renewable energy sources instead of fossil fuels. Furthermore, hydrocarbons can be produced using carbon dioxide as a raw material. Therefore, carbon dioxide contained in factory exhaust gases can be captured and effectively used as a raw material for chemical products.

[0016] Hydrogen molecules can be produced by water electrolysis. Water electrolysis can be performed using an electrolysis device described below. The hydrogen molecules may be hydrogen gas. Molecules such as ammonia and hydrocarbons can be produced using hydrogen molecules produced by water electrolysis as a raw material. Ammonia can be produced, for example, by the Haber-Bosch process using hydrogen molecules as a raw material. Hydrocarbons may contain at least one of methane and olefins. Methane can be produced by a methanation reaction using hydrogen molecules as a raw material. Olefins (alkenes) can be produced by a Fischer-Tropsch reaction using hydrogen molecules as a raw material.

[0017] The hydrogen element that exists in nature is protium ( 1 H or H), deuterium ( 2 H or D) and tritium (tritium: 3Three isotopes of hydrogen are known to exist: hydrogen (H or T). Hydrogen is the most abundant isotope of hydrogen in nature. Deuterium is a stable isotope of hydrogen. Tritium is a radioactive isotope and occurs in very small amounts in nature.

[0018] In the determination method according to this embodiment, a target molecule is determined to be an electrolytic hydrogen-containing molecule when the abundance ratio of deuterium to proton in the target molecule is equal to or less than a predetermined threshold value that is lower than the abundance ratio of deuterium to proton in nature. Electrolytic hydrogen-containing molecules produced by the method described below have a lower abundance ratio of deuterium. Therefore, if the abundance ratio of deuterium in the target molecule is lower than the abundance ratio of deuterium in nature, the target molecule can be determined to be an electrolytic hydrogen-containing molecule.

[0019] Specifically, the determination method according to this embodiment uses deuterium, a stable isotope of hydrogen, as a tracer to determine whether a target molecule is an electrolytic hydrogen-containing molecule. As will be described in detail later, deuterium molecules such as HD and D have a slower reaction rate than protium molecules such as H. Therefore, the abundance ratio of deuterium to protium in the hydrogen molecules obtained by water electrolysis using this difference in reaction rate is lower than the abundance ratios of HDO and DO to H2O in the electrolytic cell feed water. Therefore, when the abundance ratio of deuterium to protium in the target molecule is equal to or lower than a predetermined threshold value that is lower than the abundance ratio of deuterium to protium in nature, the target molecule can be determined to be an electrolytic hydrogen-containing molecule.

[0020] The abundance ratio of deuterium to protons in hydrogen molecules obtained by water electrolysis as described above is lower than the abundance ratio of deuterium to protons in nature. Therefore, hydrogen-containing molecules such as ammonia or hydrocarbons produced using hydrogen molecules produced by water electrolysis as a raw material also have the same deuterium abundance ratio as the hydrogen molecules. On the other hand, the abundance ratio of deuterium to protons in hydrogen obtained by steam reforming of fossil fuels such as natural gas is equivalent to the abundance ratio of deuterium to protons in nature. Therefore, the abundance ratio of deuterium to protons in hydrogen-containing molecules such as ammonia or hydrocarbons produced using hydrogen molecules with a lower hydrogen abundance ratio than the natural hydrogen abundance ratio as a raw material also becomes lower than the natural deuterium abundance ratio.

[0021] The abundance ratio of deuterium to protium in a target molecule can be obtained by calculating the molar ratio of deuterium to protium contained in the target molecule. Specifically, the abundance ratio of deuterium to protium in a target molecule is the molar ratio of molecules containing at least one deuterium atom to molecules consisting only of protium atoms among the molecules contained in the target molecule. The abundance ratio of deuterium can be obtained using a mass spectrometer. The abundance ratio of deuterium may be obtained using a mass spectrometer combined with a separation device such as a gas chromatograph. The abundance ratio of deuterium can also be obtained using a combination of a gas chromatograph and a detector such as a TCD (Thermal Conductivity Detector).

[0022] The abundance ratio of deuterium to protons in nature is said to be 184 ppm or less. Therefore, the abundance ratio of deuterium to protons in nature may be, for example, 184 ppm or less. Alternatively, the abundance ratio of deuterium to protons in nature may be the abundance ratio of deuterium to protons in Vienna Standard Mean Seawater (VSMOW). The abundance ratio of deuterium to protons in Vienna Standard Mean Seawater is approximately 155 ppm.

[0023] The threshold value should be smaller than the abundance ratio of deuterium to protium in nature. The threshold value may be, for example, 120 ppm, 100 ppm, 80 ppm, 60 ppm, 40 ppm, 20 ppm, or 10 ppm. When the abundance ratio of deuterium is small, it is easy to determine whether the target molecule is an electrolytic hydrogen-containing molecule. The threshold value may be greater than 0 ppm.

[0024] As described above, the determination method according to this embodiment is a method for determining whether a target molecule containing hydrogen element is an electrolytic hydrogen-containing molecule that includes hydrogen molecules produced by water electrolysis or molecules produced using the hydrogen molecules as a raw material. This determination method determines that the target molecule is an electrolytic hydrogen-containing molecule when the abundance ratio of deuterium to protons in the target molecule is equal to or less than a predetermined threshold value that is lower than the abundance ratio of deuterium to protons in nature.

[0025] As described above, hydrogen molecules obtained by water electrolysis utilizing a reaction rate difference or molecules produced using the hydrogen molecules as a raw material have a low deuterium abundance ratio. Therefore, if the deuterium abundance ratio of the target molecule is lower than the deuterium abundance ratio in nature, the target molecule can be determined to be an electrolytic hydrogen-containing molecule. Therefore, the determination method according to this embodiment makes it possible to confirm whether the target molecule is hydrogen produced by water electrolysis or a molecule produced using the hydrogen as a raw material.

[0026] Furthermore, because water electrolysis can be performed using renewable energy, the determination method according to this embodiment makes it possible to determine that a target molecule is a molecule produced using renewable energy. That is, by measuring the abundance ratio of deuterium to protium in the target molecule, it becomes possible to establish traceability for molecules produced using renewable energy. The method according to this embodiment is particularly useful as a sampling inspection at the time of receiving goods. Because the method according to this embodiment is useful as a sampling inspection, the analysis results of the produced electrolytic hydrogen-containing molecules can be attached to the product as a quality record to ensure quality.

[0027] That is, the method according to this embodiment may be a quality assurance method for assuring that a target molecule containing hydrogen is an electrolytic hydrogen-containing molecule that includes hydrogen molecules produced by water electrolysis or molecules produced using hydrogen molecules as a raw material. The quality assurance method may assure that the target molecule is an electrolytic hydrogen-containing molecule when the abundance ratio of deuterium to protons in the target molecule is equal to or less than a predetermined threshold value that is lower than the abundance ratio of deuterium to protons in nature.

[0028] According to the quality assurance method of this embodiment, when a target molecule is received, the abundance ratio of deuterium to proton in the target molecule is analyzed, thereby confirming the quality of the target molecule. Furthermore, according to the quality assurance method of this embodiment, the abundance ratio of deuterium to proton in the target molecule is analyzed before the target molecule is shipped, thereby guaranteeing the quality of the target molecule to be shipped. The quality of the target molecule may be attached to the product as a warranty or label.

[0029] The determination method may be performed by a determination device including a determination unit. The determination device may include, for example, a measurement unit, a determination unit, and an output unit. The measurement unit may include a device that measures the abundance ratio of deuterium to protium in the target molecule. The measurement unit may include, for example, a mass spectrometer. The measurement unit may be a combination of a mass spectrometer with a separation device such as a gas chromatograph, or may include a combination of a gas chromatograph and a detector.

[0030] The determination unit determines whether a target molecule containing hydrogen element is an electrolytic hydrogen-containing molecule containing a hydrogen molecule produced by water electrolysis or a molecule produced using hydrogen molecules as a raw material. The determination unit determines that the target molecule is an electrolytic hydrogen-containing molecule when the abundance ratio of deuterium to proton in the target molecule is equal to or less than a predetermined threshold value that is lower than the abundance ratio of deuterium to proton in nature. The determination unit may determine that the target molecule is an electrolytic hydrogen-containing molecule when the abundance ratio of deuterium to proton in the target molecule acquired by the measurement unit is equal to or less than a predetermined threshold value that is lower than the abundance ratio of deuterium to proton in nature. The signal of the deuterium abundance ratio data output from the measurement unit may be output to the determination unit, and the determination unit may acquire the data output from the measurement unit. The determination unit may be, for example, a computer including a CPU (central processing unit) and memory. The CPU can load a determination program stored in the memory and determine whether the target molecule is an electrolytic hydrogen-containing molecule based on the abundance ratio of deuterium to proton in the target molecule acquired by the measurement unit and the threshold value. The output unit outputs the determination result determined by the determination unit. Examples of the output unit include a monitor and a printer. The output unit can output a determination result to the output unit, for example, that "the target molecule is an electrolytic hydrogen-containing molecule" or "the target molecule is not an electrolytic hydrogen-containing molecule."

[0031] (electrolyzer) Next, an electrolysis device according to this embodiment will be described. The electrolysis device according to this embodiment can perform the water electrolysis described in the above embodiment. The electrolysis device according to this embodiment may be a low-temperature water electrolysis device or a medium- to high-temperature steam electrolysis device.

[0032] (Low temperature water electrolysis device) First, an example of a low-temperature water electrolysis apparatus will be described with reference to Fig. 1. As shown in Fig. 1, the electrolysis apparatus 1 according to this embodiment includes an electrolytic cell 10, a circulation flow path 20, a water supply flow path 30, and a wastewater flow path 40.

[0033] The electrolytic cell 10 electrolyzes water. Hydrogen and oxygen are produced by the electrolysis of water. The electrolysis method used in the electrolytic cell 10 may be alkaline water electrolysis, solid polymer water electrolysis, or a combination of these. The electrolysis method used in the electrolytic cell 10 may be PEM (Proton Exchange Membrane) water electrolysis, alkaline water electrolysis, and AEM (Anion Exchange Membrane) water electrolysis, etc.

[0034] The electrolytic cell 10 includes a membrane 11, a cathode 12, and an anode 13. The electrolytic cell 10 includes a DC power supply (not shown) electrically connected to the cathode 12 and the anode 13, and water is electrolyzed by applying a voltage to the cathode 12 and the anode 13.

[0035] The circulation flow path 20 circulates water electrolyzed in the electrolytic cell 10. Pure water is typically used as the water supplied to the electrolysis device 1, and circulating the water allows for effective use of the pure water. A water supply flow path 30 and a water discharge flow path 40 are connected to the circulation flow path 20. The water supply flow path 30 supplies pure water to the circulation flow path 20. The pure water may have an electrical resistivity of 0.1 Ω·cm or more at 25°C. The electrical resistivity of the pure water may be 20 MΩ·cm or less, 10 MΩ·cm or less, or 1.5 MΩ·cm or less. The water discharge flow path 40 is located downstream of the electrolytic cell 10 and upstream of the water supplied via the water supply flow path 30, and discharges some or all of the water in the circulation flow path 20. A flow rate regulator 41 that adjusts the amount of water discharged from the circulation flow path 20 may be provided in the water discharge flow path 40. The flow rate regulator 41 can adjust the flow rate of water flowing in the drainage flow path 40, and can adjust the amount of water in the circulation flow path 20 that is discharged from the drainage flow path 40. This makes it possible to adjust the deuterium abundance ratio of the hydrogen molecules generated in the electrolytic cell 10. The flow rate regulator 41 may be a flow rate control valve or the like.

[0036] The circulation flow path 20 may include a cathode-side water supply pipe 21, an anode-side water supply pipe 22, a cathode-side drain pipe 23, and an anode-side drain pipe 24. The electrolysis device 1 may include an electrolyte water supply tank 50 provided in the circulation flow path 20, a hydrogen gas-liquid separator 60 provided in the circulation flow path 20, and an oxygen gas-liquid separator 65 provided in the circulation flow path 20. A pump 25 is provided in the cathode-side water supply pipe 21. A pump 26 is provided in the anode-side water supply pipe 22. The hydrogen gas-liquid separator 60 is provided in the cathode-side drain pipe 23. The oxygen gas-liquid separator 65 is provided in the anode-side drain pipe 24.

[0037] Make-up water is supplied to the electrolyte supply tank 50 via the water supply passage 30, and water for electrolysis in the electrolytic cell 10 is stored therein. The outlet of the electrolyte supply tank 50 is connected to the inlet on the cathode 12 side of the electrolytic cell 10 via the cathode-side water supply pipe 21. Water is supplied from the electrolyte supply tank 50 to the cathode 12 side of the electrolytic cell 10 by driving the pump 25. The outlet of the electrolyte supply tank 50 is connected to the inlet on the anode 13 side of the electrolytic cell 10 via the anode-side water supply pipe 22. Water is supplied from the electrolyte supply tank 50 to the anode 13 side of the electrolytic cell 10 by driving the pump 26.

[0038] The outlet of the electrolytic cell 10 on the cathode 12 side is connected to the inlet of the electrolyte water supply tank 50 via a cathode side drain pipe 23. A hydrogen gas-liquid separator 60 is provided in the cathode side drain pipe 23. The outlet of the electrolytic cell 10 on the anode 13 side is connected to the inlet of the electrolyte water supply tank 50 via an anode side drain pipe 24. An oxygen gas-liquid separator 65 is provided in the anode side drain pipe 24. Water that has passed through the electrolytic cell 10 is supplied to the hydrogen gas-liquid separator 60 together with the hydrogen gas produced at the cathode 12, and is supplied to the oxygen gas-liquid separator 65 together with the oxygen gas produced at the anode 13.

[0039] In the hydrogen-gas-liquid separator 60, hydrogen produced by electrolysis in the cathode 12 is separated from water discharged without being electrolyzed in the electrolytic cell 10. The hydrogen separated in the hydrogen-gas-liquid separator 60 is recovered and stored, for example, in a storage tank. Meanwhile, the water separated in the hydrogen-gas-liquid separator 60 is supplied to the electrolyte water supply tank 50 through the cathode-side drain pipe 23.

[0040] In the oxygen-gas-liquid separator 65, oxygen generated by electrolysis at the anode 13 is separated from water that was not electrolyzed in the electrolytic cell 10 and was discharged. The oxygen separated in the oxygen-gas-liquid separator 65 is stored in, for example, a storage tank. Meanwhile, the water separated in the oxygen-gas-liquid separator 65 is supplied to the electrolyte water supply tank 50 through the anode-side drain pipe 24.

[0041] The electrolyte supply tank 50 stores water that has not been electrolyzed in the electrolytic cell 10 and is discharged from the electrolytic cell 10 , and the water circulates between the electrolytic cell 10 and the electrolyte supply tank 50 .

[0042] The electrolysis device 1 may include a control unit 70. The control unit 70 may be electrically connected to at least one selected from the group consisting of the electrolytic cell 10, the pump 25, the pump 26, and the flow rate regulator 41. The control unit 70 may control at least one of the applied voltage and the current density of the electrolytic cell 10. The control unit 70 may control the flow rate of water supplied to the electrolytic cell 10 by operating at least one of the pump 25 and the pump 26. The control unit 70 may control the flow rate of water in the circulation flow path 20 that is discharged from the discharge flow path 40 by operating the flow rate regulator 41. By controlling these factors, the abundance ratio of deuterium to protium in the hydrogen molecules generated in the electrolytic cell 10 can be adjusted.

[0043] Next, the electrolysis reactions in the PEM water electrolysis apparatus, alkaline water electrolysis apparatus, and AEM water electrolysis apparatus will be described in detail.

[0044] (PEM type water electrolysis device) First, an example of a PEM water electrolysis apparatus will be described with reference to Fig. 2. As shown in Fig. 2, in a PEM water electrolysis apparatus, water is supplied to the anode 13 through the anode-side water supply pipe 22 of the electrolytic cell 10. At the anode 13, oxygen and hydrogen ions (H + ) is generated. The membrane 11 is a PEM, and hydrogen ions (H + ) permeates the membrane 11 and moves from the anode 13 side to the cathode 12 side. At the cathode 12, hydrogen gas is produced from the hydrogen ions that permeated the membrane 11. Water may be supplied to the cathode 12 side through the cathode side water supply pipe 21, but it is not necessary to supply water through the cathode side water supply pipe 21.

[0045] Deuterium ions (D + ) permeates the membrane 11 at a rate of + ) permeates the membrane 11 at a slower rate than the rate at which HDO and DO permeate the membrane 11. + The rate at which H is produced is + is generated at a rate slower than the rate at which deuterium gases such as HD gas and D2 gas are generated at the cathode 12. Therefore, the amount of deuterium gases such as HD gas and D2 gas generated at the cathode 12 is smaller than the amount of protium gas generated at the cathode 12. Therefore, the abundance ratio of deuterium to protium in the hydrogen molecules generated by the PEM water electrolysis apparatus is smaller than the abundance ratio of deuterium to protium in the water supplied to the electrolytic cell 10.

[0046] (Alkaline water electrolysis device) Next, an example of an alkaline water electrolysis apparatus will be described with reference to Fig. 3. As shown in Fig. 3, in the alkaline water electrolysis apparatus, water is supplied to the cathode 12 and the anode 13 of the electrolytic cell 10 through a cathode-side water supply pipe 21 and an anode-side water supply pipe 22, respectively. In the cathode 12, hydrogen and hydroxide ions (OH - ) is produced. - ) permeates the membrane 11 and moves from the cathode 12 side to the anode 13 side. At the anode 13, hydroxide ions (OH -) to generate oxygen. The membrane 11 is a diaphragm, and the diaphragm may contain at least one selected from the group consisting of polysulfone, PTFE (polytetrafluoroethylene), asbestos, polyolefin, and an anion exchange membrane (AEM). The anion exchange membrane may be a resin having a quaternary ammonium group and an imidazolium group. The alkaline water passing through the electrolytic cell 10 may contain an aqueous solution of an alkali metal hydroxide. The alkali metal hydroxide may contain at least one of sodium hydroxide and potassium hydroxide.

[0047] Cathode 12 is used to convert HDO and DO to OD. - The rate at which HD gas and D2 gas are produced is - and H gas are produced at a rate slower than the rate at which HD gas and D gas are produced. Therefore, the amount of deuterium gas, such as HD gas and D gas, produced at cathode 12 is smaller than the amount of protium gas produced. Therefore, the abundance ratio of deuterium to protium in the hydrogen molecules produced in the alkaline water electrolysis apparatus is smaller than the abundance ratio of deuterium to protium in the water supplied to electrolytic cell 10.

[0048] (AEM type water electrolysis device) Next, an example of an AEM water electrolysis apparatus will be described with reference to Fig. 4. As shown in Fig. 4, in the AEM water electrolysis apparatus, water is supplied to the anode 13 of the electrolytic cell 10 through the anode-side water supply pipe 22. The water permeates the membrane 11, which is an AEM, and moves from the anode 13 side to the cathode 12 side. At the cathode 12, hydrogen and hydroxide ions (OH - ) is generated at the cathode 12. - ) permeates the membrane 11 and moves from the cathode 12 side to the anode 13 side. At the anode 13, hydroxide ions (OH - ) to generate oxygen and water. Water may be supplied to the cathode 12 side through the cathode side water supply pipe 21, but water does not necessarily have to be supplied through the cathode side water supply pipe 21.

[0049] The rate at which HDO and DO permeate the membrane 11 is slower than the rate at which HO permeates the membrane 11. Furthermore, the rate at which HD gas and D gas are produced from HDO and DO at the cathode 12 is slower than the rate at which H gas is produced from HO. Therefore, the amount of deuterium gas, such as HD gas and D gas, produced at the cathode 12 is less than the amount of hydrogen gas produced. Therefore, the abundance ratio of deuterium to hydrogen in the hydrogen molecules produced by the AEM water electrolysis apparatus is smaller than the abundance ratio of deuterium to hydrogen in the water supplied to the electrolytic cell 10.

[0050] (medium-high temperature steam electrolysis equipment) Next, an example of a medium- to high-temperature steam electrolysis device will be described with reference to Fig. 5. In the electrolysis device 1 according to this embodiment, the electrolysis method in the electrolytic cell 10 may be SOEC (Solid Oxide Electrolysis Cell) water electrolysis, PCEC (Protonic Ceramic Electrolysis Cell) water electrolysis, or a combination of these. As shown in Fig. 5, the electrolysis device 1 according to this embodiment further includes a heat exchanger 80 provided in the circulation flow path 20. Other than this, the device is similar to the low-temperature water electrolysis device shown in Fig. 1, and therefore description thereof will be omitted.

[0051] The heat exchanger 80 exchanges heat between water supplied to the electrolytic cell 10 and water discharged from the electrolytic cell 10. The heat exchanger 80 may include a first heat exchanger provided across the cathode-side water supply pipe 21 and the cathode-side drain pipe 23, and a second heat exchanger provided across the anode-side water supply pipe 22 and the anode-side drain pipe 24. The first heat exchanger can exchange heat between water supplied to the cathode 12 side of the electrolytic cell 10 and water discharged from the cathode 12 side of the electrolytic cell 10. The second heat exchanger can exchange heat between water supplied to the anode 13 side of the electrolytic cell 10 and water discharged from the anode 13 side of the electrolytic cell 10. Instead of the heat exchanger 80, a heater (not shown) for heating the water supplied to the electrolytic cell 10 may be provided in at least one of the cathode-side water supply pipe 21 and the anode-side water supply pipe 22.

[0052] Next, the electrolysis reactions in the SOEC water electrolysis system and the PCEC water electrolysis system will be described in detail.

[0053] (SOEC type water electrolysis equipment) An example of an SOEC water electrolysis apparatus will be described with reference to Fig. 6. As shown in Fig. 6, in an SOEC water electrolysis apparatus, water vapor is supplied to a cathode 12 of an electrolytic cell 10 through a cathode-side water supply pipe 21. In the cathode 12, hydrogen gas and oxygen ions (O 2- ) is generated. Oxygen ions (O 2- ) permeates the membrane 11 and moves from the cathode 12 side to the anode 13 side. At the anode 13, oxygen ions (O 2- ) to produce oxygen gas.

[0054] The rate at which HD gas and D gas are produced from HDO and D O at the cathode 12 is slower than the rate at which H gas is produced from H O. Therefore, the amount of deuterium gas, such as HD gas and D gas, produced at the cathode 12 is less than the amount of hydrogen gas produced. Therefore, the abundance ratio of deuterium to hydrogen in the hydrogen molecules produced in the SOEC water electrolysis apparatus is smaller than the abundance ratio of deuterium to hydrogen in the water supplied to the electrolytic cell 10.

[0055] (PCEC type water electrolysis device) Next, an example of a PCEC water electrolysis apparatus will be described with reference to Fig. 7. As shown in Fig. 7, in the PCEC water electrolysis apparatus, water vapor is supplied to the anode 13 through the anode-side water supply pipe 22. At the anode 13, oxygen gas and hydrogen ions (H + ) is produced. Hydrogen ions (H + ) permeates the membrane 11 and moves from the anode 13 side to the cathode 12 side. At the cathode 12, the hydrogen ions (H + ) to produce hydrogen gas.

[0056] Deuterium ions (D +) permeates the membrane 11 at a rate of + ) permeates the membrane 11 at a slower rate than the rate at which HDO and DO permeate the membrane 11. + The rate at which H is produced is + is generated at a rate slower than the rate at which deuterium gases such as HD gas and D2 gas are generated. Therefore, the amount of deuterium gases such as HD gas and D2 gas generated at the cathode 12 is smaller than the amount of proton gas. Therefore, the abundance ratio of deuterium to proton in the hydrogen molecules generated by the PCEC water electrolysis apparatus is smaller than the abundance ratio of deuterium to proton in the water supplied to the electrolytic cell 10.

[0057] As described above, in either electrolysis method, the abundance ratio of deuterium to protons in the generated hydrogen molecules is lower than the abundance ratio of deuterium to protons in the water supplied to the electrolytic cell 10. On the other hand, the abundance ratio of deuterium to protons in the water discharged from the electrolytic cell 10 is higher than the abundance ratio of deuterium to protons in the water supplied to the electrolytic cell 10. In the electrolysis device 1 according to this embodiment, some or all of the water in the circulation flow path 20 is discharged by the discharge flow path 40, and pure water is supplied to the circulation flow path 20 by the water supply flow path 30. Therefore, the abundance ratio of deuterium to protons in the water flowing in the circulation flow path 20 is diluted and reduced, and the abundance ratio of deuterium to protons in the hydrogen molecules generated in the electrolytic cell 10 is further reduced. Therefore, the abundance ratio of deuterium to protons in the hydrogen molecules generated by water electrolysis in the electrolytic cell 10 is lower than the abundance ratio of deuterium to protons in nature.

[0058] As shown in FIG. 8, the water supplied to the electrolytic cell 10 may be alkaline water, and the electrolysis device 1 may further include a membrane separation device 90. The membrane separation device 90 may be provided in the wastewater flow path 40. The membrane separation device 90 may include a permeable membrane that selectively allows the water in the alkaline water to pass through. The semipermeable membrane selectively allows the water in the alkaline water to pass through. The semipermeable membrane allows the water in the alkaline water to pass through but does not allow metal ions such as sodium ions and potassium ions to pass through. Therefore, it is possible to discharge only water without discharging alkaline water outside the circulation flow path 20.

[0059] The semipermeable membrane may include at least one selected from the group consisting of a flat membrane, a hollow fiber membrane, and a spiral membrane. The pore size of the semipermeable membrane may be large enough to allow water molecules to pass through but not allow sodium ions and the like in the water to be treated to pass through. The pore size of the semipermeable membrane may be 0.5 nm or more, or 1 nm or more. The pore size of the semipermeable membrane may be 10 nm or less, 5 nm or less, or 2 nm or less. The semipermeable membrane may be a reverse osmosis membrane (RO membrane). The semipermeable membrane may include at least one selected from the group consisting of cellulose acetate, polyacrylonitrile, polysulfone, polyethersulfone, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic.

[0060] Next, the abundance ratio of deuterium to protons was evaluated by simulation when the electrolysis device shown in Figure 1 was operated under various conditions. The operating conditions are shown in Table 1, and the abundance ratio of deuterium to protons is shown in Table 2.

[0061] [Table 1]

[0062] [Table 2]

[0063] In Table 1, the water utilization rate is the volume ratio of the amount of water consumed by electrolysis to the amount of water supplied to the electrolytic cell. The water supplied to the electrolytic cell is water supplied to the electrolytic cell 10 through the cathode side water supply pipe 21 and the anode side water supply pipe 22. The water consumed by electrolysis is water consumed by electrolysis in the electrolytic cell 10.

[0064] The separation factor is a value expressed by the following formula:

[0065] α=([D] L ) / ([D] G )

[0066] In the above formula, α is the separation factor, [D] Lis the ratio of deuterium to hydrogen in the electrolytic cell feed water, and [D] G indicates the abundance ratio of deuterium to protium in the hydrogen gas (hydrogen molecules) generated in the electrolytic cell 10.

[0067] The separation factor can be controlled by using the applied voltage and current density, which are the operating conditions of the electrolytic cell 10, as manipulated variables. The smaller the applied voltage, the smaller the abundance ratio of deuterium to protons in the hydrogen molecules produced. Also, the smaller the current density, the smaller the abundance ratio of deuterium to protons in the hydrogen molecules produced. Furthermore, the separation factor can also be controlled by selecting the metal species of the electrode catalyst. The separation factor tends to increase in the order Cu > Fe > Ni > Ag > Au > Pt > Sn.

[0068] The blowdown ratio is the volume ratio of the flow rate of blown water to the flow rate of produced water. The produced water is water that is not electrolyzed in the electrolytic cell 10 and is discharged from the electrolytic cell 10. The blown water is water that is discharged from the drainage flow path 40. The flow rate is the amount of water per unit time. The amount of hydrogen gas generated is the amount of hydrogen gas (hydrogen molecules) generated by electrolysis in the electrolytic cell 10.

[0069] In Table 2, make-up water is pure water supplied to circulation flow path 20 through water supply flow path 30. The ratio of deuterium to proton in the pure water is set to 150 ppm. As described above, electrolytic cell supply water is water supplied to electrolytic cell 10. The electrolytic cell supply water is a mixture of make-up water and water that is produced and circulates within circulation flow path 20 without being discharged as blow-down water. In this example, the ratio of deuterium to proton in the electrolytic cell supply water is higher than the ratio of deuterium to proton in the make-up water.

[0070] As shown in Table 2, the ratio of deuterium to protium in the hydrogen gas generated in the electrolytic cell 10 can be controlled by adjusting the operating conditions of the electrolysis device. Specifically, the lower the water utilization rate, the more the deuterium ratio can be reduced. Furthermore, the larger the separation factor, the more the deuterium ratio can be reduced. Furthermore, the higher the blowdown rate, the more the deuterium ratio can be reduced.

[0071] Therefore, at least one selected from the group consisting of the water utilization rate, separation factor, and blowdown ratio may be controlled. The water utilization rate is the ratio of the amount of water consumed by electrolysis in the electrolytic cell 10 to the amount of water supplied to the electrolytic cell. The separation factor is the ratio of the amount of deuterium to protons in the water supplied to the electrolytic cell 10 to the amount of deuterium to protons in the hydrogen molecules generated in the electrolytic cell 10. The blowdown ratio is the ratio of the flow rate of water discharged in the drainage step to the flow rate of water discharged from the electrolytic cell 10. By generating hydrogen molecules with a low deuterium abundance ratio through the above-mentioned operating operations, it is possible to more easily distinguish them from hydrogen molecules derived from fossil fuels. These controls may be performed by the control unit 70 controlling the electrolytic cell 10, pumps 25 and 26, and flow rate regulator 41.

[0072] By measuring the deuterium abundance ratio of the target molecule and finding that the deuterium abundance ratio of the hydrogen molecule is comparable to that calculated based on the operating conditions in Table 1, it is easy to determine that the target molecule is an electrolytic hydrogen-containing molecule. Furthermore, by comparing the deuterium abundance ratio with the specifications issued by the manufacturer of the renewable energy-derived fuel or raw material, the quality of the target molecule can be guaranteed.

[0073] As described above, the electrolysis device 1 according to this embodiment comprises an electrolytic cell 10 that electrolyzes water, a circulation flow path 20 through which the water electrolyzed in the electrolytic cell 10 circulates, and a water supply flow path 30 that supplies pure water to the circulation flow path 20. The electrolysis device 1 also comprises a drainage flow path 40 that drains some or all of the water in the circulation flow path 20, downstream of the electrolytic cell 10 and upstream of the water supply via the water supply flow path 30. The abundance ratio of deuterium to protons in the hydrogen molecules produced by water electrolysis in the electrolytic cell 10 is smaller than the abundance ratio of deuterium to protons in nature.

[0074] The electrolysis method according to this embodiment includes an electrolysis step of electrolyzing water in an electrolytic cell 10, and a water supply step of supplying pure water to a circulation flow path 20 that circulates the water electrolyzed in the electrolytic cell 10. The electrolysis method also includes a drainage step of draining some or all of the water in the circulation flow path 20 downstream of the electrolytic cell 10 and upstream of the water supplied in the water supply step. The abundance ratio of deuterium to protons in the hydrogen molecules produced by water electrolysis in the electrolytic cell 10 is smaller than the abundance ratio of deuterium to protons in nature.

[0075] In the electrolysis device and electrolysis method according to this embodiment, water is electrolyzed in the electrolytic cell 10. The abundance ratio of deuterium to protons in the hydrogen molecules generated in the electrolytic cell 10 is smaller than the abundance ratio of deuterium to protons in the water supplied to the electrolytic cell 10. On the other hand, the abundance ratio of deuterium to protons in the water discharged from the electrolytic cell 10 is larger than the abundance ratio of deuterium to protons in the water supplied to the electrolytic cell 10. In the electrolytic device 1 according to this embodiment, some or all of the water in the circulation flow path 20 is discharged by the discharge flow path 40, and pure water is supplied to the circulation flow path 20 by the water supply flow path 30. Therefore, the abundance ratio of deuterium to protons in the water flowing in the circulation flow path 20 is diluted and reduced, and the abundance ratio of deuterium to protons in the hydrogen molecules generated in the electrolytic cell 10 is further reduced. Therefore, the abundance ratio of deuterium to protons in the hydrogen molecules generated by water electrolysis in the electrolytic cell 10 is smaller than the abundance ratio of deuterium to protons in nature.

[0076] On the other hand, when the water in the circulation flow path 20 is not drained, all of the water supplied to the electrolytic cell 10 is eventually electrolyzed, and the abundance ratio of deuterium to protons in the hydrogen molecules generated in the electrolytic cell 10 becomes the same as the abundance ratio of deuterium to protons in nature. Therefore, the electrolysis device and electrolysis method according to this embodiment can reduce the abundance ratio of deuterium to protons in the hydrogen molecules compared to when the water in the circulation flow path 20 is not drained. Furthermore, by generating molecules such as ammonia and hydrocarbons using hydrogen molecules with a reduced abundance ratio as a raw material, the abundance ratio of deuterium to protons in the generated molecules can be reduced.

[0077] Therefore, the electrolysis device and electrolysis method according to this embodiment make it possible to easily confirm whether or not the target molecule is hydrogen produced by water electrolysis or a molecule produced using the hydrogen as a raw material.

[0078] The entire contents of Patent Application No. 2022-175572 (filing date: November 1, 2022) are incorporated herein by reference.

[0079] Although several embodiments have been described, the embodiments can be modified or varied based on the above disclosure. All components of the above embodiments and all features described in the claims may be individually extracted and combined, unless they contradict each other.

[0080] This disclosure can contribute, for example, to the achievement of Goal 7 of the Sustainable Development Goals (SDGs) led by the United Nations, "Ensure access to affordable, reliable, sustainable and modern energy for all," Goal 12, "Ensure sustainable consumption and production patterns," and Goal 13, "Take urgent action to combat climate change and its impacts." [Explanation of symbols]

[0081] 1 Electrolyzer 10 Electrolytic cell 20 Circulation flow path 30 Water supply channel 40 Drainage channel 90 Membrane separation equipment

Claims

1. A method for determining whether a target molecule containing a hydrogen element is an electrolytic hydrogen-containing molecule including a molecule produced using hydrogen molecules produced by water electrolysis as a raw material, comprising: determining that the target molecule is the electrolytic hydrogen-containing molecule when the abundance ratio of deuterium to proton in the target molecule is equal to or less than a predetermined threshold value that is lower than the abundance ratio of deuterium to proton in nature; A method for determining that the target molecule is ammonia or a hydrocarbon.

2. A quality assurance method for assuring that target molecules containing hydrogen elements are electrolytic hydrogen-containing molecules including molecules produced using hydrogen molecules produced by water electrolysis as a raw material, comprising: Ascertaining that the target molecule is the electrolytic hydrogen-containing molecule when the abundance ratio of deuterium to proton in the target molecule is equal to or less than a predetermined threshold value that is lower than the abundance ratio of deuterium to proton in nature; A quality assurance method wherein the target molecule is ammonia or a hydrocarbon.

3. a determination unit that determines whether or not a target molecule containing hydrogen element is an electrolytic hydrogen-containing molecule that includes a molecule produced using hydrogen molecules produced by water electrolysis as a raw material; the determination unit determines that the target molecule is the electrolytic hydrogen-containing molecule when the abundance ratio of deuterium to proton in the target molecule is equal to or less than a predetermined threshold value that is lower than the abundance ratio of deuterium to proton in nature; The determination device, wherein the target molecule is ammonia or a hydrocarbon.

4. a measurement unit for measuring the abundance ratio of deuterium to protium of the target molecule; a determination unit that determines that the target molecule is the electrolytic hydrogen-containing molecule when the abundance ratio of deuterium to protons in the target molecule obtained by the measurement unit is equal to or less than a predetermined threshold value that is lower than the abundance ratio of deuterium to protons in nature; an output unit that outputs the determination result determined by the determination unit; The determination device according to claim 3 , comprising:

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