Method and system for producing hydrogen, deuterium and oxygen gases by electrolysis of water

Abstract

To provide a gas production method capable of stably producing hydrogen gas, deuterium gas and oxygen gas, and also capable of producing the gases on site at a production site of a semiconductor product or the like.SOLUTION: The method for producing gaseous hydrogen, gaseous deuterium and gaseous oxygen by electrolysis of water includes obtaining gaseous oxygen, gaseous hydrogen and heavy water by solid polymer electrolyte membrane water electrolysis to which a water circulation system A is applied and obtaining gaseous oxygen and gaseous deuterium by subjecting the heavy water to solid polymer electrolyte membrane water electrolysis to which a water circulation system B is applied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and system for producing hydrogen gas, deuterium gas, and oxygen gas by electrolysis of water. [Background technology]

[0002] BACKGROUND ART Conventionally, various gases have been used in the manufacture of various industrial products. For example, hydrogen (H2) gas is used as a carrier gas and for reduction purposes. Recently, its use in extreme ultraviolet lithography (EUV) lithography, a semiconductor ultrafine processing technology, has been attracting attention. EUV lithography is being increasingly adopted in Japan, and large amounts of hydrogen gas are required to cool the process chamber and prevent carbon contamination within the process chamber. Furthermore, in semiconductor manufacturing, greenhouse gases such as perfluorocompound (PFC) gases are typically treated by combustion using city gas or propane gas. However, this combustion treatment process emits carbon dioxide. Therefore, to reduce the environmental impact, research and development is being conducted on combustion treatment technologies using hydrogen gas. Furthermore, the market for hydrogen gas as a clean energy source is expanding amid recent global efforts toward a decarbonized society. Deuterium (D2) gas is known to be used in the annealing process for forming gate oxide films in semiconductor manufacturing. Annealing using deuterium gas instead of hydrogen gas effectively reduces film defects. Deuterium gas is also used as a moderator and coolant in nuclear reactors, and in the pharmaceutical field as a solvent for radiation therapy and nuclear magnetic resonance (NMR) spectroscopy. Furthermore, deuterated drugs incorporating carbon (C)-deuterium (D) bonds are less likely to be broken down in the body than drugs incorporating carbon (C)-hydrogen (H) bonds, thereby extending the duration of their efficacy. However, deuterium gas is rare and expensive, primarily because its precursor, deuterium oxide (D2O), is found in natural water in trace amounts of approximately 160 ppm. Oxygen (O2) gas is used as an oxidizing agent to form a silicon oxide film (SiO2) on silicon wafers, and also as an additive gas in the etching process.

[0003] Several techniques for separating and recovering such gases are known. For example, Patent Document 1 describes a technique for recovering deuterium gas by synthesizing heavy water (DO) from deuterium gas in exhaust gases generated during semiconductor manufacturing, separating the synthesized heavy water (DO), and further electrolyzing the synthesized heavy water. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-31403 Summary of the Invention [Problem to be solved by the invention]

[0005] The aforementioned hydrogen gas, deuterium gas, and oxygen gas are essential in the manufacture of electronic components, particularly semiconductor products, and therefore a stable supply of these gases is required. In view of the above, an object of the present invention is to provide a gas production method that can stably produce hydrogen gas, deuterium gas, and oxygen gas, and that can also produce the gases on-site at manufacturing sites of semiconductor products, etc. Another object of the present invention is to provide a gas production system suitable for carrying out the above gas production method. [Means for solving the problem]

[0006] The present invention provides the following technical means. [1] A method for producing hydrogen gas, deuterium gas, and oxygen gas by electrolysis of water, comprising obtaining oxygen gas, hydrogen gas, and heavy water by solid polymer electrolyte membrane water electrolysis using the following water circulation system A, and then subjecting this heavy water to solid polymer electrolyte membrane water electrolysis using the following water circulation system B to obtain oxygen gas and deuterium gas: <Water circulation system A> A water circulation system in which water in the oxygen gas separation tank 1A is supplied to the solid polymer electrolyte membrane water electrolysis device 2A, oxygen gas generated on the anode side of the solid polymer electrolyte membrane water electrolysis device 2A is returned to the oxygen gas separation tank 1A together with the supplied water, hydrogen gas generated on the cathode side of the solid polymer electrolyte membrane water electrolysis device 2A is supplied to the hydrogen gas separation tank 3 together with water that has permeated the solid polymer electrolyte membrane, and the water supplied to the hydrogen gas separation tank 3 is returned to the oxygen gas separation tank 1A. <Water circulation system B> A water circulation system in which heavy water in the oxygen gas separation tank 1B is supplied to the solid polymer electrolyte membrane water electrolysis device 2B, oxygen gas generated on the anode side of the solid polymer electrolyte membrane water electrolysis device 2B is returned to the oxygen gas separation tank 1B together with the supplied heavy water, deuterium gas generated on the cathode side of the solid polymer electrolyte membrane water electrolysis device 2B is supplied to the deuterium gas separation tank 4 together with the heavy water that has permeated the solid polymer electrolyte membrane, and the heavy water supplied to the deuterium gas separation tank 4 is returned to the oxygen gas separation tank 1B. [2] The method for producing hydrogen gas, deuterium gas and oxygen gas according to [1], wherein the hydrogen gas, deuterium gas and oxygen gas are gases to be used in the manufacturing process of semiconductor products. [3] The method for producing hydrogen gas, deuterium gas, and oxygen gas by electrolysis of water according to [2], wherein the manufacturing process of the semiconductor product includes at least one of extreme ultraviolet exposure treatment or combustion detoxification treatment using the hydrogen gas, annealing treatment of a gate oxide film using the deuterium gas, and formation treatment of a gate oxide film using the oxygen gas. [4] [3] The method for producing hydrogen gas, deuterium gas, and oxygen gas by electrolysis of water according to [3], wherein a recovery line for the oxygen gas and / or hydrogen gas and / or deuterium gas used is installed in the manufacturing process of the semiconductor product. [5] [4] The method for producing hydrogen gas, deuterium gas, and oxygen gas by electrolysis of water according to [4], wherein the deuterium gas recovery line includes at least one of a distillation method, a dual temperature exchange method which is an exchange reaction between hydrogen atoms and deuterium atoms via hydrogen sulfide, and a membrane separation method. [6] a water circulation system A described below that produces oxygen gas, hydrogen gas, and heavy water by solid polymer electrolyte membrane water electrolysis; a water circulation system B for producing oxygen gas and deuterium gas by subjecting the heavy water to solid polymer electrolyte membrane water electrolysis, the water circulation system B being as follows: <Water circulation system A> A water circulation system in which water in the oxygen gas separation tank 1A is supplied to the solid polymer electrolyte membrane water electrolysis device 2A, oxygen gas generated on the anode side of the solid polymer electrolyte membrane water electrolysis device 2A is returned to the oxygen gas separation tank 1A together with the supplied water, hydrogen gas generated on the cathode side of the solid polymer electrolyte membrane water electrolysis device 2A is supplied to the hydrogen gas separation tank 3 together with water that has permeated the solid polymer electrolyte membrane, and the water supplied to the hydrogen gas separation tank 3 is returned to the oxygen gas separation tank 1A. <Water circulation system B> A water circulation system in which heavy water in the oxygen gas separation tank 1B is supplied to the solid polymer electrolyte membrane water electrolysis device 2B, oxygen gas generated on the anode side of the solid polymer electrolyte membrane water electrolysis device 2B is returned to the oxygen gas separation tank 1B together with the supplied heavy water, deuterium gas generated on the cathode side of the solid polymer electrolyte membrane water electrolysis device 2B is supplied to the deuterium gas separation tank 4 together with the heavy water that has permeated the solid polymer electrolyte membrane, and the heavy water supplied to the deuterium gas separation tank 4 is returned to the oxygen gas separation tank 1B. [Effects of the Invention]

[0007] According to the method for producing hydrogen gas, deuterium gas, and oxygen gas of the present invention (hereinafter also referred to as the "gas production method of the present invention"), hydrogen gas, deuterium gas, and oxygen gas can be stably produced. The gases can also be produced on-site at manufacturing sites of semiconductor products, etc. Furthermore, the system for producing hydrogen gas, deuterium gas, and oxygen gas of the present invention (hereinafter also referred to as the "gas production system of the present invention") can suitably carry out the gas production method described above. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing an embodiment of a system used in a method for producing hydrogen gas, deuterium gas, and oxygen gas according to the present invention. FIG. [Figure 2] FIG. 2 is a schematic diagram of a solid polymer electrolyte membrane water electrolysis device 2A used in a water circulation system A. [Figure 3] FIG. 2 is a schematic diagram showing one embodiment of changes in the concentrations of H 2 O and D 2 O in a solid polymer electrolyte membrane water electrolysis device 2A in a water circulation system A. [Figure 4] 10 is a schematic diagram showing another embodiment of changes in the concentrations of H2O and D2O in a solid polymer electrolyte membrane water electrolysis device 2A in a water circulation system A. FIG. [Figure 5] 1 is a schematic diagram of a solid polymer electrolyte membrane water electrolysis device 2B used in a water circulation system B. FIG. [Figure 6] FIG. 1 is a schematic diagram showing a preferred embodiment of the method for producing hydrogen gas, deuterium gas, and oxygen gas of the present invention, including a process for producing the various gases, a process for providing the gases to a process for producing industrial products, a detoxification process, and a recovery process. DETAILED DESCRIPTION OF THE INVENTION

[0009] A preferred embodiment of the gas production method of the present invention will be described below with reference to the drawings. However, the gas production method of the present invention and the gas production system of the present invention described below are not limited to those using the configuration of system 100 shown in Fig. 1 except as defined in the present invention. For example, various instrumentation devices such as a concentration meter, a flow meter, and a pressure meter may be included to include a step of measuring the flowing gas.

[0010] 1 includes a mechanism for operating, in this order, a water circulation system A and a water circulation system B. The system 100 further includes a water tank WT, a separator 5, a concentrator 6, and dehumidifiers R1 to R4. The water tank WT supplies water to water circulation system A. In water circulation system A, water is circulated and subjected to solid polymer electrolyte membrane water electrolysis to produce oxygen gas and hydrogen gas, and heavy water is obtained during this circulation. Separator 5 supplies the heavy water to water circulation system B. In water circulation system B, heavy water is circulated and subjected to solid polymer electrolyte membrane water electrolysis to produce oxygen gas and deuterium gas. The deuterium gas is concentrated in concentrator 6. In water circulation systems A and B, the water is dehumidified by dehumidifiers R1 to R4, respectively, to separate hydrogen gas, deuterium gas, and oxygen gas, which are then supplied to the manufacturing processes of semiconductor products and various other products.

[0011] The "water" supplied from the water tank WT is ordinary water, which generally contains about 160 ppm of deuterium oxide. This "water" is preferably pure water from the viewpoint of more appropriately performing proton exchange membrane water electrolysis in water circulation systems A and B. This pure water is water from which impurities such as salts, organic matter, and ionic substances have been removed, and generally refers to water with an electrical resistivity of 0.1 to 1.5 MΩ cm. Furthermore, "heavy water" as used here refers to water that contains a large amount of water molecules (deuterium oxide: DO) with a large mass number isotope (D: deuterium), and has a higher specific gravity than regular water. Specifically, heavy water is defined as water with a higher concentration of deuterium oxide than the approximately 160 ppm found in regular water. The aforementioned "semiconductor product" refers to any device that can function by utilizing the characteristics of semiconductor elements. Electro-optical devices in which semiconductor elements are connected to a substrate, semiconductor circuit boards, stacks of multiple semiconductor elements, and electronic devices that contain these are all included in semiconductor products. Electronic components such as multilayer wiring boards for connecting semiconductor elements are also included in semiconductor products.

[0012] <Water circulation system A> The water circulation system A supplies water in the oxygen gas separation tank 1A to the solid polymer electrolyte membrane water electrolysis device 2A, and returns oxygen gas generated on the anode side of the solid polymer electrolyte membrane water electrolysis device 2A to the oxygen gas separation tank 1A together with the supplied water. At the same time, it supplies hydrogen gas generated on the cathode side of the solid polymer electrolyte membrane water electrolysis device 2A to the hydrogen gas separation tank 3 together with water that has permeated the solid polymer electrolyte membrane, and returns the water supplied to the hydrogen gas separation tank 3 to the oxygen gas separation tank 1A. Water circulation is performed in this manner. Solid polymer electrolyte membrane water electrolysis using this water circulation system A is carried out to obtain oxygen gas, hydrogen gas, and heavy water.

[0013] More specifically, oxygen gas, hydrogen gas, and heavy water are obtained as follows. First, by controlling the opening and closing of valve B1, a certain amount of water is supplied from the water tank WT through supply line L1 to water circulation system A. In water circulation system A, the oxygen gas separation tank 1A receives the water and supplies it to the solid polymer electrolyte membrane water electrolysis device 2A through supply line L2.

[0014] As the solid polymer electrolyte membrane water electrolysis device 2A, various configurations typically used for water electrolysis can be used without particular limitation. The solid polymer electrolyte membrane water electrolysis device 2A shown in FIG. 2 has an anode on one side of a solid polymer electrolyte membrane 21 and a cathode on the other side. The anode has an electrocatalyst layer 22, a power supply 23, an electrode plate 24, and an anode chamber 25. Similarly, the cathode has an electrocatalyst layer 26, a power supply 27, an electrode plate 28, and a cathode chamber 29. These components can be made of various materials typically used for water electrolysis without particular limitation.

[0015] In the solid polymer electrolyte membrane water electrolysis device 2A, supplied water is taken in from the anode side, and electrolysis of the water occurs in the anode chamber 25. As a result, water molecules (HO) are converted into oxygen (O) gas and hydrogen ions (H + ) and electrons (e - ) (The solid polymer electrolyte membrane water electrolysis device 2A in the water circulation system A is also referred to as a proton exchange membrane 2A). The oxygen gas is returned to the oxygen gas separation tank 1A together with the supplied water via a supply line L3. In the oxygen gas separation tank 1A, a dehumidifier R1 dehumidifies the water via a recovery line L4 to separate the oxygen gas from the supplied water, and the separated oxygen gas is recovered and provided to various manufacturing processes. The hydrogen ions move through the solid polymer electrolyte membrane 21 to the cathode chamber 29, where they combine with electrons to form hydrogen gas. The hydrogen gas, together with water that has permeated the solid polymer electrolyte membrane, is supplied to the hydrogen gas separation tank 3 via supply line L5. In the hydrogen gas separation tank 3, a dehumidifier R2 dehumidifies the water via recovery line L6 to separate the hydrogen gas from the water that has permeated the solid polymer electrolyte membrane, and the separated hydrogen gas is recovered and supplied to various manufacturing processes. The separated water is returned to the oxygen gas separation tank 1A via supply line L7. The water returned via the supply lines L3 and L7 is electrolyzed again in the solid polymer electrolyte membrane water electrolysis device 2A via the supply line L2. In this way, the supplied water is circulated, causing repeated electrolysis of water to repeatedly generate oxygen gas and hydrogen gas.

[0016] In water circulation system A, the water supplied from water tank WT generally contains about 160 ppm of deuterium oxide (DO), as mentioned above. Because HO is more easily electrolyzed than DO, and because the DO concentration is extremely low in water circulation system A, the electrolysis of HO takes precedence. As a result, when water is repeatedly electrolyzed through circulation, oxygen gas and hydrogen gas are obtained from H2O. At the same time, in the oxygen gas separation tank 1A, the concentration of H2O in the given amount of water supplied decreases while the concentration of D2O increases, making it possible to efficiently obtain heavy water. In this way, oxygen gas, hydrogen gas, and heavy water can be obtained by solid polymer electrolyte membrane water electrolysis using the water circulation system A.

[0017] In the solid polymer electrolyte membrane water electrolysis apparatus 2A, the amount of electricity applied also affects the electrolysis of H2O and D2O. Therefore, from the viewpoint of suitably implementing the above-described concentration change, it is preferable to control the amount of electricity applied in the solid polymer electrolyte membrane water electrolysis apparatus 2A to an extent that does not cause electrolysis of D2O.

[0018] When heavy water with a certain concentration or higher is obtained in the oxygen gas separation tank 1A, valve B2 is opened and the heavy water is transferred to the water circulation system B via supply line L8. At the same time, valve B1 is opened again to supply a certain amount of water from the water tank WT to the water circulation system A via supply line L1. In this way, in the water circulation system A, each time a fixed amount of water is repeatedly supplied, the batch processing of producing oxygen gas, hydrogen gas, and heavy water, and transferring the heavy water to the water circulation system B can be repeatedly performed.

[0019] By repeatedly performing the batch treatment in water circulation system A, the concentration of HO repeatedly decreases and the concentration of DO repeatedly increases in the oxygen gas separation tank 1A. For example, as shown in FIG. 3, the concentration of HO, which was nearly 100% in the initially supplied water, decreases as the solid polymer electrolyte membrane water electrolysis is repeated, and the concentration of DO increases, resulting in heavy water (first batch treatment). After the heavy water is transferred to water circulation system B, the next water supply (water supply) is performed to water circulation system A. This increases the concentration of HO again. Next, the aforementioned concentration change occurs through repeated solid polymer electrolyte membrane water electrolysis, and heavy water is again obtained (second batch treatment). This concentration change due to batch treatment is repeated in the oxygen gas separation tank 1A. As shown in FIG. 3, the concentration of H2O may be reduced to the limit (close to 0%) and the concentration of D2O may be increased to nearly 100% before the next batch processing is performed, or as shown in FIG. 4, the concentration of H2O may be reduced to a certain value just before the limit (close to 0%) and the concentration of D2O may be increased to a certain value before the next batch processing is performed. In this regard, if the mass of H2O circulating through the water circulation system A decreases too much as the DO concentration increases, this may hinder the continuation of the water circulation operation. From the viewpoint of minimizing this possibility as much as possible, the latter (Fig. 4) is preferable to the former (Fig. 3). That is, as in the latter, it is preferable to perform solid polymer electrolyte membrane water electrolysis within the range that allows continuous operation in the water circulation system A, and then open valve B2 to discharge heavy water in the oxygen gas separation tank 1A, in which the DO concentration has been increased from the initial value. At this timing, it is preferable to open valve B1 again to replenish new water into the oxygen gas separation tank 1A and resume electrolysis. The timing for discharging the heavy water is preferably when the DO concentration is 50% by mass or more, more preferably 75% or more.

[0020] <Water circulation system B> The water circulation system B supplies the heavy water in the oxygen gas separation tank 1B to the solid polymer electrolyte membrane water electrolysis device 2B, and returns the oxygen gas generated on the anode side of the solid polymer electrolyte membrane water electrolysis device 2B together with the supplied heavy water to the oxygen gas separation tank 1B. At the same time, the deuterium gas generated on the cathode side of the solid polymer electrolyte membrane water electrolysis device 2B is supplied to the deuterium gas separation tank 4 together with the heavy water that has permeated the solid polymer electrolyte membrane, and the heavy water supplied to the deuterium gas separation tank 4 is returned to the oxygen gas separation tank 1B. In this way, the water circulation system is performed. By subjecting the heavy water to solid polymer electrolyte membrane water electrolysis using this water circulation system B, oxygen gas and deuterium gas are obtained.

[0021] More specifically, oxygen gas and deuterium gas are obtained as follows. First, it is preferable that the transfer of heavy water from the water circulation system A to the water circulation system B be carried out via a separator 5 . When heavy water contains H2O, the separator 5 separates a certain amount of H2O from the heavy water, further increasing the concentration of D2O in the heavy water. In the water circulation system B, H2O interferes with the generation of deuterium (D2) gas from D2O, so it is preferable that the heavy water sent to the oxygen gas separation tank 1B have a high D2O concentration. Therefore, it is preferable to separate H2O using the separator 5, increase the D2O concentration, and supply it to the oxygen gas separation tank 1B. This allows for more accurate electrolysis of the heavy water in the solid polymer electrolyte membrane electrolysis device 2B. This is particularly effective when the H2O concentration is at a certain level, as shown in Figure 4. Furthermore, by reducing the H2O concentration using the separator 5, the water circulation system B can further reduce the presence of hydrogen (H2) gas in the deuterium gas separation tank 4 and further reduce the presence of hydrogen (H2) gas in the concentrator 6 (described below). This more effectively prevents hydrogen (H2) gas contamination in the supply line L16. Furthermore, if the concentration of D2O in the separator 5 can be made as close to 100% as possible, it will be possible to create a system that does not include the concentration device 6 described below. The separator 5 supplies the heavy water from which a certain amount of H2O has been separated via a supply line L9 to the water circulation system B. The separated H2O is returned via a supply line L10 to the oxygen gas separation tank 1A of the water circulation system A and is again subjected to electrolysis in the solid polymer electrolyte membrane water electrolysis device 2A. In the water circulation system B, the oxygen gas separation tank 1B receives the heavy water, and supplies this heavy water to the solid polymer electrolyte membrane water electrolysis device 2B via a supply line L11.

[0022] As the separator 5, various types that are commonly used in the technical fields that handle water and gas can be used without any particular limitation, for example, distillation method and membrane separation method.

[0023] As described above, various configurations and materials typically used for water electrolysis can be used for the solid polymer electrolyte membrane water electrolysis device 2B without any particular limitations. The solid polymer electrolyte membrane water electrolysis device 2B shown in Fig. 5 has the same configuration as the solid polymer electrolyte membrane water electrolysis device 2A described above. Furthermore, the volume of heavy water electrolyzed in the solid polymer electrolyte membrane water electrolysis device 2B is overwhelmingly smaller than the volume of water electrolyzed in the solid polymer electrolyte membrane water electrolysis device 2A. Therefore, the solid polymer electrolyte membrane water electrolysis device 2B is preferably smaller in scale than the solid polymer electrolyte membrane water electrolysis device 2A. The smaller scale makes it easier to perform electrolysis of DO more effectively and efficiently.

[0024] In the solid polymer electrolyte membrane water electrolysis device 2B, the supplied heavy water is taken in from the anode side and electrolytic electrolysis of the heavy water occurs in the anode chamber 25. This converts deuterium oxide (DO) into oxygen (O) gas and deuterium ions (DO). + ) and electrons (e - ) The oxygen gas is returned to the oxygen gas separation tank 1B together with the supplied heavy water via the supply line L12. In the oxygen gas separation tank 1B, the dehumidifier R3 dehumidifies the air via the recovery line L13 to separate the oxygen gas from the supplied heavy water, and the separated oxygen gas is recovered and provided to various manufacturing processes. The deuterium ions pass through the solid polymer electrolyte membrane 21 and move to the cathode chamber 29, where they combine with electrons to form deuterium gas. The deuterium gas, along with heavy water that has permeated the solid polymer electrolyte membrane, is supplied to the deuterium gas separation tank 4 via supply line L14. In the deuterium gas separation tank 4, a dehumidifier R4 dehumidifies the deuterium gas and the supplied heavy water via recovery line L15, and the separated deuterium gas is recovered and supplied to various manufacturing processes. The separated heavy water is returned to the oxygen gas separation tank 1B via supply line L17.

[0025] 1, it is preferable that the deuterium gas is concentrated in a concentrator 6 and then supplied to various production equipment 81 via a supply line L16. This removes hydrogen H gas generated when H2O mixed in from the water circulation system A is electrolyzed in the solid polymer electrolyte membrane water electrolysis device 2B, thereby enabling the production of higher purity deuterium (D2) gas.

[0026] As the concentrator 6, various types commonly used in the technical fields of water and gas handling can be used without any particular limitation, for example, cryogenic distillation and membrane separation.

[0027] The separation of deuterium (D2) gas and hydrogen (H2) gas by the concentrator 6 can be carried out in accordance with various forms in which the two gases are generated. For example, as mentioned above, H2O is electrolyzed preferentially over D2O. In situations where gases are generated at different times, the concentrator 6 first recovers hydrogen gas (H2) through the recovery line L15, followed by deuterium (D2) gas. When the gas species are switched in this way, it is preferable for the concentrator 6 to switch between the hydrogen (H2) gas supply line L18 and the deuterium (D2) gas supply line L16. In addition, when hydrogen (H2) gas and deuterium (D2) gas are generated as a mixture, they are separated in the concentrator 6, recovered via respective supply lines L16 and L18, and provided to various manufacturing processes, respectively. From the viewpoint of further enhancing these functions, it is preferable to detect the type of gas generated by installing a concentration meter (not shown) together with the concentrator 6. By detecting the concentration meter, it is possible to more accurately switch between the supply lines L18 and L16 and separate the gases.

[0028] In the water circulation system B, the heavy water returned via the supply lines L12 and L17 is electrolyzed again in the solid polymer electrolyte membrane water electrolysis device 2B via the supply line 11. In this way, the supplied heavy water is circulated, causing repeated electrolysis of the heavy water and repeatedly generating oxygen gas and deuterium gas.

[0029] As described above, the gas production method of the present invention produces oxygen gas, hydrogen gas, and heavy water by solid polymer electrolyte membrane water electrolysis using water circulation system A, and then produces oxygen gas and deuterium gas by subjecting this heavy water to solid polymer electrolyte membrane water electrolysis using the following water circulation system B. This allows hydrogen gas, deuterium gas, and oxygen gas to be stably produced. The gas production system of the present invention is a system for suitably carrying out the gas production method of the present invention, and includes the following water circulation system A that produces oxygen gas, hydrogen gas, and heavy water by the above-described solid polymer electrolyte membrane water electrolysis, and the following water circulation system B that produces oxygen gas and deuterium gas by subjecting the heavy water to solid polymer electrolyte membrane water electrolysis. Hydrogen gas, deuterium gas, and oxygen gas are preferably used in the manufacturing process of industrial products, and in particular, at semiconductor manufacturing sites, the above gases can be produced and used on-site.

[0030] Furthermore, the system 100 preferably has the following configuration as shown in FIG. That is, the system 100 preferably includes an industrial product manufacturing apparatus 81 using deuterium gas and a deuterium gas separation apparatus 82 at the end of a supply line L16 that supplies deuterium gas. The deuterium gas separation apparatus 82 preferably has a function of recovering deuterium gas-containing exhaust gas from the manufacturing apparatus 81 via a supply line L19 and separating the exhaust gas into deuterium gas and other exhaust gases. Furthermore, the deuterium gas separation apparatus 82 preferably has a supply line L20 that connects the exhaust gas to a treatment apparatus such as a detoxification treatment apparatus, and a supply line L21 that supplies the separated deuterium gas to the deuterium gas separation tank 4 of the water circulation system B. As a result, the system 100 can not only produce various gases, but also reduce the amount of rare deuterium gas that leaks out during its use, thereby enabling effective reuse. As a result, it is possible to effectively utilize the rare gas resource of deuterium gas, ensure a stable supply, and reduce the cost of purchasing new gas. Furthermore, by feeding back the deuterium gas separated from the exhaust gas to the deuterium gas separation tank 4 in the water circulation system B, the tank can be used as a deuterium buffer tank. Moreover, the deuterium (D2) gas separated from the exhaust gas, together with new deuterium (D2) gas generated in the solid polymer electrolyte membrane water electrolysis device 2B, can be supplied to the production equipment 81 as purified high-purity deuterium (D2) gas via the dehumidifier R4 and concentrator 6 subsequent to the recovery line L15.

[0031] The deuterium gas separation device 82 preferably has a function of implementing various recovery methods for deuterium gas, which preferably include at least one of a distillation method, a dual temperature exchange method which is an exchange reaction between hydrogen atoms and deuterium atoms via hydrogen sulfide, and a membrane separation method.

[0032] As described above, the gas production method of the present invention preferably includes a recovery step in which all of the hydrogen gas, deuterium gas, and oxygen gas produced are directly supplied to an industrial product production process, and the exhaust gas is subjected to a detoxification treatment step, while the gas is separated from the exhaust gas and fed back for reuse (circulation). This makes it possible to effectively utilize resources, ensure a stable gas supply, and reduce the cost of purchasing new gas, as described above. For example, as shown in FIG. 6, water circulation systems A and B of system 100 are used to perform solid polymer electrolyte membrane water electrolysis to produce hydrogen gas, deuterium gas, and oxygen gas, which are then stored in tanks 61-63. Vacuum pumps (VPs) 71-73 are used to draw gas from tanks 61-63 and supply it to manufacturing equipment 81, 84, and 86 for use in the industrial product manufacturing process. The exhaust gases from manufacturing equipment 81, 84, and 86 are transferred to detoxification treatment devices 83, 85, and 87 for detoxification treatment. These detoxification devices 83, 85, and 87 may be devices capable of implementing any of a variety of detoxification methods based on various principles, such as combustion, catalytic, or plasma, or a combination of these methods. The detoxification treatment devices 83, 85, and 87 further remove harmful substances from the wastewater, which is then treated for wastewater treatment or disposed of as sludge.

[0033] As for the recovery step, it is preferable that a recovery line be installed at least at one location between the manufacturing equipment 81, 84, and 86 and the detoxification treatment equipment 83, 85, and 87. The recovery line performs the recovery step of separating oxygen gas and / or hydrogen gas and / or deuterium gas from the exhaust gas and feeding the separated gas back to the water circulation system A and the water circulation system B of the system 100 for reuse. In particular, in view of the scarcity of deuterium gas, it is preferable to have a recovery line that separates deuterium gas from the exhaust gas by installing the deuterium gas separation device 82 described above between the production device 81 and the detoxification treatment device 83. The recovery line performs a recovery step in which the deuterium gas separated in the deuterium gas separation device 82 is supplied via a supply line L21 to the deuterium gas separation tank 4 of the water circulation system B. As for the deuterium gas recovery line, it is preferable that the deuterium gas recovery method includes at least one of the distillation method, the double temperature exchange method which is an exchange reaction between hydrogen atoms and deuterium atoms via hydrogen sulfide, and the membrane separation method, as described above.

[0034] Manufacturing processes using hydrogen gas, deuterium gas, and oxygen gas can be found in various technical fields. For example, the manufacturing processes include manufacturing processes for electronic components including semiconductor products such as semiconductors and liquid crystal displays, and manufacturing processes for pharmaceuticals. In particular, semiconductor manufacturing processes are preferred as manufacturing processes that use all of hydrogen gas, deuterium gas, and oxygen gas. The manufacturing process of the semiconductor product preferably includes at least one of an extreme ultraviolet exposure process or a combustion detoxification process using hydrogen gas, an annealing process of a gate oxide film using deuterium gas, and a process of forming a gate oxide film using oxygen gas. The term "semiconductor product manufacturing process" as used here refers to the process of manufacturing semiconductor products in a broad sense, including not only the process of forming semiconductor products but also peripheral processing steps such as combustion abatement treatment.

[0035] When the manufacturing process of the aforementioned industrial product incorporated into the gas manufacturing method and gas manufacturing system of the present invention is a semiconductor manufacturing process, the pure water that is normally used in the semiconductor manufacturing process can be used directly to produce hydrogen gas, deuterium gas, and oxygen gas, which has the advantage of reducing the effort and cost required to procure new materials. Furthermore, when the manufacturing process of the industrial product described above, into which the gas production method and gas production system of the present invention are incorporated, is a semiconductor manufacturing process, there is an advantage in that the process from production to recycling of the gases can be carried out consistently on-site within the semiconductor manufacturing line by a recovery process in which hydrogen gas, deuterium gas, and oxygen gas are separated from the exhaust gas and fed back for reuse (circulation). This makes it possible to particularly effectively realize effective use of resources, a stable gas supply, and a reduction in the cost of purchasing new gas. Furthermore, in the future, in cutting-edge semiconductor manufacturing, the number of processes and the amount of gas used therein are expected to increase with miniaturization and stacking, and a stable supply of each gas that serves as the source gas is directly linked to stable semiconductor manufacturing. The gas manufacturing method and gas manufacturing system of the present invention are significant from the viewpoint of enabling a stable supply of the source gas and preventing production from being interrupted due to a shortage of the source gas. Of the source gas, water, and electricity, which are essential utilities in semiconductor manufacturing processes, the gas manufacturing method and gas manufacturing system of the present invention can ensure a stable supply of one of these. [Explanation of symbols]

[0036] 1A, 1B Oxygen gas separation tank 2A, 2B Solid polymer electrolyte membrane water electrolysis device 3 Hydrogen gas separation tank 4. Deuterium gas separation tank 5 Separator 6 Concentrator WT Water Tank B1, B2 valves R1~R4 Dehumidifier 100 systems

Claims

1. A method for producing hydrogen gas, deuterium gas, and oxygen gas by electrolysis of water, comprising obtaining oxygen gas, hydrogen gas, and heavy water by solid polymer electrolyte membrane water electrolysis using the following water circulation system A, and then subjecting this heavy water to solid polymer electrolyte membrane water electrolysis using the following water circulation system B to obtain oxygen gas and deuterium gas: <Water circulation system A> A water circulation system in which water in the oxygen gas separation tank 1A is supplied to the solid polymer electrolyte membrane water electrolysis device 2A, oxygen gas generated on the anode side of the solid polymer electrolyte membrane water electrolysis device 2A is returned to the oxygen gas separation tank 1A together with the supplied water, hydrogen gas generated on the cathode side of the solid polymer electrolyte membrane water electrolysis device 2A is supplied to the hydrogen gas separation tank 3 together with water that has permeated the solid polymer electrolyte membrane, and the water supplied to the hydrogen gas separation tank 3 is returned to the oxygen gas separation tank 1A. <Water circulation system B> A water circulation system in which heavy water in the oxygen gas separation tank 1B is supplied to the solid polymer electrolyte membrane water electrolysis device 2B, oxygen gas generated on the anode side of the solid polymer electrolyte membrane water electrolysis device 2B is returned to the oxygen gas separation tank 1B together with the supplied heavy water, deuterium gas generated on the cathode side of the solid polymer electrolyte membrane water electrolysis device 2B is supplied to the deuterium gas separation tank 4 together with the heavy water that has permeated the solid polymer electrolyte membrane, and the heavy water supplied to the deuterium gas separation tank 4 is returned to the oxygen gas separation tank 1B.

2. 2. The method for producing hydrogen gas, deuterium gas and oxygen gas according to claim 1, wherein the hydrogen gas, deuterium gas and oxygen gas are gases for use in the manufacturing process of semiconductor products.

3. 3. The method for producing hydrogen gas, deuterium gas, and oxygen gas by electrolysis of water according to claim 2, wherein the manufacturing process of the semiconductor product includes at least one of an extreme ultraviolet exposure process or a combustion detoxification process using the hydrogen gas, an annealing process of a gate oxide film using the deuterium gas, and a process of forming a gate oxide film using the oxygen gas.

4. 4. The method for producing hydrogen gas, deuterium gas, and oxygen gas by electrolysis of water according to claim 3, wherein a recovery line for the oxygen gas and / or hydrogen gas and / or deuterium gas used is installed in the manufacturing process of the semiconductor product.

5. 5. The method for producing hydrogen gas, deuterium gas, and oxygen gas by electrolysis of water according to claim 4, wherein the deuterium gas recovery line is provided using a method for recovering the deuterium gas that includes at least one of a distillation method, a dual temperature exchange method which is an exchange reaction between hydrogen atoms and deuterium atoms via hydrogen sulfide, and a membrane separation method.

6. a water circulation system A described below that produces oxygen gas, hydrogen gas, and heavy water by solid polymer electrolyte membrane water electrolysis; a water circulation system B for producing oxygen gas and deuterium gas by subjecting the heavy water to solid polymer electrolyte membrane water electrolysis, the water circulation system B being as follows: <Water circulation system A> A water circulation system in which water in the oxygen gas separation tank 1A is supplied to the solid polymer electrolyte membrane water electrolysis device 2A, oxygen gas generated on the anode side of the solid polymer electrolyte membrane water electrolysis device 2A is returned to the oxygen gas separation tank 1A together with the supplied water, hydrogen gas generated on the cathode side of the solid polymer electrolyte membrane water electrolysis device 2A is supplied to the hydrogen gas separation tank 3 together with water that has permeated the solid polymer electrolyte membrane, and the water supplied to the hydrogen gas separation tank 3 is returned to the oxygen gas separation tank 1A. <Water circulation system B> A water circulation system in which heavy water in the oxygen gas separation tank 1B is supplied to the solid polymer electrolyte membrane water electrolysis device 2B, oxygen gas generated on the anode side of the solid polymer electrolyte membrane water electrolysis device 2B is returned to the oxygen gas separation tank 1B together with the supplied heavy water, deuterium gas generated on the cathode side of the solid polymer electrolyte membrane water electrolysis device 2B is supplied to the deuterium gas separation tank 4 together with the heavy water that has permeated the solid polymer electrolyte membrane, and the heavy water supplied to the deuterium gas separation tank 4 is returned to the oxygen gas separation tank 1B.

Images