Deuterium recovery device and deuterium recovery method

Abstract

Deuterium is recovered with high efficiency and low power consumption. [Solution] A DC voltage is applied between the first catalytic electrode 11 and the second catalytic electrode 12, with the first catalytic electrode 11 side being positive and the second catalytic electrode 12 side being negative. The first catalytic electrode 11 side serves as an anode chamber 31 to which deuterium (D) to be recovered is supplied as a gas together with hydrogen (H). The second catalytic electrode 12 side serves as a cathode chamber 32 in which water W, primarily composed of HO, is stored in contact with the second catalytic electrode 12. The H and D in the anode chamber 31 flow to the second catalytic electrode 12 side as voltage is applied. Thereafter, due to a reaction with the water, etc. in the cathode chamber 32, only the D component of H and D is preferentially absorbed into the water (liquid) therein, while the H component is removed as a gas. This allows D to be recovered into this water with high efficiency.

Description

[Technical Field]

[0001] The present invention relates to hydrogen ( 1 The present invention relates to a deuterium recovery device and a deuterium recovery method that selectively recover deuterium from a mixture of hydrogen (H) and deuterium. [Background technology]

[0002] A stable isotope of hydrogen that is a component of naturally occurring water and hydrogen gas has a mass number of 1 (the nucleus consists of only one proton). 1 H (hereafter referred to as H) and deuterium, which has a mass number of 2 (the nucleus consists of one proton and one neutron). 2 There is H (hereafter referred to as D), and the abundance ratio of D is overwhelmingly smaller than that of H. H and D have almost the same chemical properties, but D is known to be particularly effective in applications in the nuclear power and semiconductor manufacturing fields. For this reason, there is a demand for technology to selectively extract (separate) D from water or hydrogen gas, which contains a mixture of H and D. However, since it is practically impossible to completely separate H and D instantly, in reality, materials containing a mixture of these (water, hydrogen gas, etc.) are treated to increase the concentration of one of them (especially D) in order to separate them.

[0003] Because the chemical properties of H and D are nearly identical, they are generally not easily separated by chemical methods, and various separation methods (or methods for concentrating D) are known. A known technique is to obtain a gas or liquid containing H and D with a higher D concentration from the gas or liquid by using a membrane electrode assembly (MEA) equipped with a catalyst / proton conducting layer / catalyst structure similar to that used in fuel cells. In a gas or liquid containing H and D, D exists in the form of, for example, D2, HD (a gas corresponding to H2), or HDO, DO (a liquid or gas corresponding to HO).

[0004] Patent Document 1 describes a technique for increasing the D concentration using such a membrane electrode assembly by using an exchange reaction between H and D in hydrogen gas and water vapor on a catalyst (vapor phase chemical exchange reaction: VPCE reaction). The VPCE reaction is shown in the following reaction formula (1).

[0005]

number

[0006] Here, (g) indicates the gas phase. HD(g) on ​​the left side is a component supplied from the outside that permeates the MEA and is produced on the catalyst, while HO(g) on ​​the left side is a component (water vapor) supplied from the outside that is unrelated to HD(g). In reality, the reaction from the left side to the right side of reaction equation (1) and the reaction from the right side to the left side occur simultaneously, resulting in an equilibrium state.

[0007] The D in HDO(g) produced on the right-hand side is the D in HD(g) on ​​the left-hand side, and this HDO(g) is produced by replacing one H in HO(g) on ​​the left-hand side with D. Meanwhile, the H in HD(g) on ​​the left-hand side combines with the H in HO(g) that replaced D above on the right-hand side to form H(g), which is then separated from D and released as a gas. Therefore, if an equilibrium state is reached in which the reaction from the left side to the right side of reaction equation (1) is dominant, then by extracting HDO(g) from the input HD components, only the D component can be preferentially obtained. In other words, using the above VPCE reaction, D can be captured in steam and recovered. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-76690 Summary of the Invention [Problem to be solved by the invention]

[0009] In the technology described in Patent Document 1, both HD(g) and HO(g) on ​​the left side of Equation (1) exist as gases on the catalyst. In particular, if HO exists as a liquid on the catalyst, the gaseous HD(g) cannot reach the catalyst. Therefore, the HO(g) used in this case must be gaseous, which necessitates a mechanism for constantly heating water and supplying it as gas (water vapor). This also requires maintaining a high temperature for the membrane electrode assembly itself. Therefore, the technology described in Patent Document 1 requires high power consumption to achieve a high recovery rate.

[0010] For this reason, there was a demand for technology that could recover deuterium with high efficiency and low power consumption.

[0011] The present invention has been made in view of the above problems, and an object of the present invention is to provide an invention that solves the above problems. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention has the following configurations. The deuterium recovery device of the present invention uses hydrogen ( 1 a membrane electrode assembly having a proton conducting layer made of a proton conductor that conducts positive hydrogen ions and having two opposing main surfaces; a first catalytic electrode formed on one of the main surfaces of the proton conducting layer and having a positive voltage; and a second catalytic electrode formed on the other main surface of the proton conducting layer and having a negative voltage; an anode chamber provided on the first catalytic electrode side so that the first catalytic electrode is in contact with the input gas; and a cathode chamber in which liquid water is stored so that the second catalytic electrode is in contact with the second catalytic electrode, and the water recovered by a liquid-phase chemical exchange reaction between the deuterium ions that flow from the anode chamber side to the cathode chamber side and the water is extracted from the cathode chamber. A plurality of cells each including the membrane electrode assembly, the anode chamber, and the cathode chamber are used in stages, and the cells are connected so that the gas other than water after the reaction in the cathode chamber of the preceding cell is used as the input gas of the adjacent subsequent cell, and the cathode chamber of the cell is configured to receive recovered water, which is the water before deuterium is recovered, and discharge output water, which is the water after deuterium is recovered, and the cells are connected so that the output water of the subsequent cell is used as the recovered water of the adjacent preceding cell. It is characterized by: The first catalytic electrode and the second catalytic electrode may contain particles made of a noble metal selected from platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), and gold (Au), or an alloy containing the noble metal. 。 The deuterium is deuterium ( 2 H or D), or tritium ( 3 H or T). The deuterium recovery method of the present invention is a method for recovering hydrogen ( 1 A deuterium recovery method for recovering deuterium from an input gas containing a mixture of deuterium ions (H) and deuterium, an isotope of hydrogen, using a membrane electrode assembly including: a proton conducting layer made of a proton conductor that conducts positive hydrogen ions and having two opposing main surfaces; a first catalytic electrode formed on one of the main surfaces of the proton conducting layer and having a positive voltage; and a second catalytic electrode formed on the other main surface of the proton conducting layer and having a negative voltage; wherein the first catalytic electrode is in contact with the input gas and the second catalytic electrode is in contact with liquid water, and a voltage is applied to the first catalytic electrode at a positive potential and the second catalytic electrode at a negative potential; and the deuterium ions flow from the first catalytic electrode side to the second catalytic electrode side by a liquid-phase chemical exchange reaction between the deuterium ions and the water, and the recovered water is extracted. a plurality of cells each having the membrane electrode assembly are used in stages, and the cells are connected so that the gas other than water after the reaction on the second catalytic electrode side of the preceding cell is used as the input gas of the adjacent subsequent cell; recovered water, which is the water before the deuterium is recovered, is introduced to the second catalytic electrode side of the cell, and output water, which is the water after the deuterium is recovered, is discharged; and the cells are connected so that the output water of the subsequent cell is used as the recovered water of the adjacent preceding cell. It is characterized by: The first catalytic electrode and the second catalytic electrode contain particles made of a noble metal selected from platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), and gold (Au), or an alloy containing the noble metal. It's okay to do that. The deuterium is deuterium ( 2 H or D), or tritium ( 3 H or T). [Effects of the Invention]

[0013] Since the present invention is configured as described above, it is possible to recover deuterium with high efficiency and low power consumption. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing a configuration of a deuterium recovery device according to an embodiment of the present invention. [Figure 2] 1 shows the results of measuring the resolution α in an example of the present invention and a comparative example. [Figure 3] FIG. 2 is a diagram showing the configuration of a first modified example of a deuterium recovery device according to an embodiment of the present invention. [Figure 4] FIG. 10 is a diagram showing the configuration of a second modified example of a deuterium recovery device according to an embodiment of the present invention. [Figure 5] FIG. 10 is a diagram showing the configuration of a third modified example of a deuterium recovery device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, a deuterium recovery apparatus and a deuterium recovery method according to an embodiment of the present invention will be described. This deuterium recovery apparatus and deuterium recovery method selectively recovers D from an input gas (hydrogen gas) containing a mixture of H and D, and incorporates it into water for recovery. This makes it possible to obtain water containing a high concentration of D, or to reduce the D concentration in hydrogen gas.

[0016] In this deuterium recovery device and method, a membrane electrode assembly (MEA) is used as a basic component, similar to the device described in Patent Document 1. FIG. 1 is a diagram showing a schematic configuration of this deuterium recovery device 1. This configuration uses an MEA 10 that combines two electrodes (a first catalytic electrode 11 and a second catalytic electrode 12) to which a DC voltage is applied, and a proton conductive layer 20 sandwiched between them. Here, a DC voltage is applied between the first catalytic electrode 11 and the second catalytic electrode 12, with the first catalytic electrode 11 side being positive and the second catalytic electrode 12 side being negative.

[0017] The proton conducting layer 20 may be made of a material that is a conductor of H ions and D ions (proton conductor), such as Nafion (registered trademark). These ions flow through the proton conducting layer 20 from left to right in the drawing, and an oxidation reaction occurs again at the second catalytic electrode 12. The thickness of the proton conducting layer 20 is set to, for example, a range of 25 μm to 200 μm.

[0018] For both the first catalytic electrode 11 and the second catalytic electrode 12, a noble metal (platinum (Pt) or the like) that functions as a catalyst is used in a form that allows it to function both as an electrode and as a catalyst. For example, a form (Pt / C) is used in which Pt nanoparticles (powder) are supported on a carbon-based material to increase the surface area of ​​Pt and enhance the catalytic action. In this case, the content of the catalyst (Pt or the like) is 0.1 to 2.0 mg / cm. 2 The first catalytic electrode 11 is made of a catalytic material that oxidizes hydrogen isotopes, and the second catalytic electrode 12 is made of a catalytic material that efficiently causes a liquid-phase chemical exchange reaction, which will be described later, and in addition to Pt, noble metals such as palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), and gold (Au), as well as alloys such as PtNi and PtCo (alloys containing the above noble metals), can also be used for both.

[0019] 1, the proton conducting layer 20, the first catalytic electrode 11, and the second catalytic electrode 12 (MEA 10) are shown as simple flat plates, but by providing appropriate irregularities rather than making them flat, it is possible to substantially increase their surface area and contact area. Even in this case, the operations described below are performed in the same way, and by increasing these areas, it is possible to increase the processing capacity.

[0020] The above configuration is similar to the technology described in Patent Document 1. However, in this deuterium recovery device 1, the configuration of the side where deuterium is recovered (cathode side: second catalytic electrode 12 side) is significantly different from the technology described in Patent Document 1.

[0021] In Fig. 1, the side of the first catalytic electrode 11 is an anode chamber 31 to which hydrogen gas containing deuterium (D) to be recovered is supplied. The hydrogen gas introduced here is introduced through an inlet 31A and discharged through an outlet 31B. This allows hydrogen gas (gas) containing H and D to be stored in the anode chamber 31 while in contact with the first catalytic electrode 11. The gas introduced into the inlet 31A is not limited to hydrogen gas containing D, and may also contain other gases (N2, Ar, O2, etc.) that function as carrier gases.

[0022] 1, the side of the second catalytic electrode 12 is a cathode chamber 32 in which water W, mainly composed of HO, is stored in contact with the second catalytic electrode 12. For this reason, the cathode chamber 32 is provided with an inlet 32A through which water is introduced and an outlet 32B through which water (liquid) is discharged. In addition, an outlet 32C through which gas components generated in the cathode chamber 32 are discharged is also provided separately from the outlet 32B. However, the outlets 32B and 32C may be formed as a common outlet from which the liquid and gas are separated and taken out.

[0023] In this deuterium recovery device 1, H and D in the anode chamber 31 flow toward the second catalytic electrode 12 as voltage is applied. Thereafter, due to a reaction with water or the like in the cathode chamber 32, only the D component of H and D is preferentially incorporated into the water (liquid) therein, while the H component is removed as a gas. This allows D to be recovered into the water with high efficiency.

[0024] This principle will be explained below. Here, H and D are present in the anode chamber 31 in the form of gases such as H2, D2, and HD. As with the technology described in Patent Document 1, these molecules are decomposed by the first catalytic electrode 11, and H and D are ionized (positive ions). These ions flow through the proton conducting layer 20 to the right in the figure and reach the second catalytic electrode 12, where a gas similar to that described above is again produced. Below, we will explain the behavior of HD, a molecule formed by the combination of H and D. This HD is formed as a gas, HD(g), and as with the technology described in Patent Document 1, the reaction of equation (1) occurs here.

[0025]

number

[0026] In the technology described in Patent Document 1, H2O(g) (water vapor) is supplied from the outside, whereas in the configuration of Figure 1, water vapor is not supplied and only liquid water W (H2O(l)) is in direct contact with the second catalytic electrode 12. In reaction formula (1), HD(g) is generated and exists as small bubbles (nanobubbles) on the surface of the second catalytic electrode 12 in water. H2O(g) is supplied from the surrounding water into these nanobubbles, and this H2O(g) reacts with HD(g), causing the reaction of reaction formula (1). That is, as a result, of the HD(g) formed at the second catalytic electrode 12, D exists as HDO(g) and H exists as H2(g), both of which exist in water.

[0027] Here, HDO(g) reacts with the surrounding water (H2O(l)) according to the following reaction equation (2):

[0028]

number

[0029] Here, (l) indicates the liquid phase. HDO(g) on ​​the left side is the right side of reaction equation (1), and HO(l) is water supplied from inlet 32A in Figure 1. In this case, HDO(g) and HO(l) on the left side change phase to HDO(l) and HO(g) on ​​the right side, respectively. The reaction combining both (1) and (2) is called a liquid-phase chemical exchange reaction.

[0030] In this case, the liquid-phase HDO(l) on the right side of reaction equation (2) incorporates D from HD(g) on ​​the left side of reaction equation (1), while the H in this HD(g) is removed as H2(g) on ​​the right side of reaction equation (1). Therefore, when an equilibrium state is reached in which the reaction from the left side to the right side of reaction equation (2) is dominant, HDO(l) on the right side is produced, and this HDO(l) is obtained by removing the post-reaction water from outlet 32B. Meanwhile, this H2(g) is discharged from outlet 32C. In other words, while the technology described in Patent Document 1 uses only reaction equation (1), which is a gas-phase chemical exchange reaction, this deuterium recovery device 1 also uses reaction equation (2) to recover D in the form of liquid (water).

[0031] In reaction equation (1), D exists only in the form of HD(g) on ​​the left side. However, if, for example, D2(g) exists and HD(g) on ​​the left side of reaction equation (1) is replaced with D2(g), H2(g) on ​​the right side is replaced with HD(g). In this case, this HD(g) becomes HD(g) on ​​the left side of reaction equation (1), and ultimately, the reaction of reaction equation (1) is realized in this case as well. In other words, gas-phase chemical exchange reactions and liquid-phase chemical exchange reactions also occur for D2.

[0032] The results of actually measuring the recovery rate of D (separation ability for H) using the configuration of Figure 1 will be described. Here, the same MEA was used for all examples and comparative examples. Nafion212 (product name: Chemours) was used as the proton conductive layer 20, and the first catalytic electrode 11 and the second catalytic electrode 12 both had a Pt particle concentration of 0.5 mg / cm. 2 The potential difference between the first catalytic electrode 11 and the second catalytic electrode 12 was set to about 0.01 V. The temperature during the reaction was set to room temperature (23° C.).

[0033] Here, as a comparative example, measurements were also carried out for a comparative example in which water vapor (H2O(g)) was introduced into the cathode chamber 32 instead of liquid water W (corresponding to H2O(l)). This comparative example corresponds to the technology described in Patent Document 1. Measurements were also carried out for examples in which the concentration of heavy water (D) was varied as the water introduced into the cathode chamber 32. Here, 4.5 sccm of H2 and 0.5 sccm of D2 (H / D molar ratio = 9) were introduced into the inlet 31A. Mass gas analysis was carried out on the gas in the anode chamber 31 and the gas in the cathode chamber 32 after the reaction.

[0034] According to the above reaction equations (1) and (2), the amount of H generated in the cathode chamber 32 reflects the amount of D recovered in the liquid. Therefore, the molar ratio R of H2 to H2 in the gas was measured by mass spectrometry, and the H / D ratio R was calculated based on this. The gases evaluated here were the gas introduced into the anode chamber 31 and the gas generated in the cathode chamber 32. The H / D ratio R of the former was defined as R1, and the H / D ratio R of the latter was defined as R2, and α = R2 / R1 was calculated. When α = 1 (R1 = R2), the H / D ratio remains unchanged between the gas on the anode chamber 31 side (input side) and the gas on the cathode chamber 32 side (output side), meaning that D is not selectively incorporated into the liquid (water) on the cathode chamber 32 side (output side). On the other hand, when α > 1, this means that the D concentration in the gas in the cathode chamber 32 is decreasing, which conversely means that the D concentration in the liquid is increasing. Therefore, the above α can be used as an index of the recovery rate of D (separation ability).

[0035] In the comparative example, as described in Patent Document 1, both H2(g) and HDO(g) on ​​the right side of the above reaction formula (1) exist as gases in the cathode chamber 32. Even in this case, when the above reaction formula (1) holds, H2 and HD exist in the air, and the relationship between the H ratio of this gas and the D ratio in the water vapor during recovery is the same as in the example. Therefore, in this case as well, the above α is calculated in the same way, and this α serves as an index of the recovery rate.

[0036] Furthermore, four types of examples (Examples 1 to 4) were used here in which the D concentration in the water (before the reaction) introduced into the cathode chamber 32 was 0.015% (hereinafter referred to as 0%), 5%, 10%, and 20%. In these cases, the absolute value of the D concentration in the solution at the time of measurement varies greatly depending on the original D concentration, but in the evaluation using the above-mentioned α, only the D newly taken into the solution is evaluated, so the evaluation using α is also effective.

[0037] The measurement results of α in the comparative example and examples 1 to 4 in this case are shown in Figure 2. Here, the amount of water in the cathode chamber 32 was 10 ml. From these results, it is clear that α > 1 in all examples, and D was recovered. However, while α = 1.3 in the comparative example, α in examples 1 to 4 was 1.4 or more, all of which were larger than the comparative example. However, α increased as the D concentration decreased, reaching a maximum of 44 when D was 0%.

[0038] This means that the reaction from the left side to the right side in reaction formulas (1) and (2) becomes more dominant as the D concentration decreases. Therefore, to recover a larger amount of D as liquid (water), it is preferable to circulate water in the cathode chamber 32 so that the D concentration in the water is constantly low. A configuration for circulating water in this manner is shown in FIG. 3, corresponding to FIG. 1. In FIG. 3, the flow of liquid (water) is indicated by a solid line, and the flow of gas is indicated by a dashed line. As shown in FIG. 3, water with a low D concentration is treated as recovered water W0 in the recovered water tank 40. This recovered water W0 can be introduced through the inlet 32A, and the reacted recovered water W0 can be introduced into the tank 41 through the outlet 32B to become output water W1. In this case, the gas after the reaction can be released from the outlet 32C. This increases the D recovery efficiency.

[0039] Similarly, on the anode chamber 31 side, gas containing H and D (input gas) can be introduced into the inlet 31A, and the gas can be circulated so that after the reaction, the gas from which the H and D components have been consumed is discharged from the outlet 31B.

[0040] In Example 5, in the configuration of FIG. 3, H2 and D2 were circulated at a flow rate of 5 sccm and 5 sccm, respectively, on the anode chamber 31 side, and water with a D concentration of 0% (similar to Example 1) was used as recovered water W0. The water flow rate was set to 0.02 ml / s, and the current density between the first catalytic electrode 11 and the second catalytic electrode 12 was set to 0.2 A / cm. 2 When this is done, α=4.8 is obtained.

[0041] In the configuration of Figure 3, only a portion of the H and D components in the input gas are actually ionized in the anode chamber 31 and conducted to the cathode side, while the remaining components are discharged as is from the outlet 31B. Furthermore, of these ions conducted to the cathode chamber 32, only a portion of the H and D components actually undergo the reactions of the reaction formulas (1) and (2), while the remaining components are discharged from the outlet 32C together with H2(g) on ​​the right side of the reaction formula (1). In other words, there are D (and H) components that were present in the input gas but are discharged as gas from the outlets 31B and 32C.

[0042] When circulating gas as shown in Figure 3, the configuration (cell) of Figure 3 can be combined in multiple stages, and the D component discharged as a gas in this way can be recovered in the cell in the subsequent stage. Figure 4 shows the configuration of an example deuterium recovery device 2, which makes it possible to recover the D component that is not recovered on the cathode chamber 32 side and is discharged as a gas, using cell 1 in the first stage (left side) to cell N in the final (Nth) stage. In this case, by using the configuration (connection between cells) of Figure 4, D can be recovered with high efficiency.

[0043] In FIG. 4, in N cells (cell K is the Kth cell from the left, K=1 to N), each having the structure of FIG. 3, the input gas input to each anode chamber 31 of cell K from the inlet 31A is cell input gas G0 K On the other hand, the raw material introduced into the cathode chamber 32 from the inlet 32A is the cell recovered water W0 K In each cell K, the gas after the reaction in the anode chamber 31 and discharged from the discharge port 31B is called the anode-side exhaust gas G1. K , the cell recovery water W0 in the cathode chamber 32 KThe output water formed by collecting D and discharged from the discharge port 32B is the cell output water W1 K The gas after the reaction in the cathode chamber 32 and discharged from the discharge port 32C is the cathode side exhaust gas G2 K It is said that.

[0044] In the configuration of FIG. 4, the original input gas G0 from which D is recovered (removed) is the cell input gas G01 of the first cell 1. In addition, the tank T K (K=1 to N) is supplied with cell output water W1, which is a liquid component, from the cathode chamber 32. K and the gas component cathode side exhaust gas G2 K Among these, the cathode side exhaust gas G2 in cell K is introduced. K (K=1~N-1) is the tank T K The cell input gas G0 in the next cell K+1 via K+1 As a result, in the next cell K+1, the cathode side exhaust gas G2 K The remaining D in the cell output water W1 K+1 That is, with this configuration, D in the input gas W0 can be recovered by cells 1 to N as cell output water W1. K (K=1 to N). This increases the recovery efficiency of D. In this case, the cell input gas G0 K The concentration of D in the cell output water W1 gradually decreases from the initial stage to the final stage as D is gradually recovered. K The amount of D recovered in the anode side exhaust gas G1 in each cell also decreases from the initial stage to the final stage. K (K=1 to N), and the final stage cathode side exhaust gas G2 N is discharged to the outside.

[0045] In addition, in the same way that the gas from which D is recovered flows between the cells, in the configuration of FIG. 4, the water from which D is recovered is also shared by flowing between the cells. That is, the tank T K Cell output water W1 Kis the cell recovered water W0 in the previous cell K-1 K-1 In addition, the cell recovery water W0 N becomes recovered water W0 with a low D concentration (zero D concentration). That is, the water flows in the opposite direction to the gas flow, from right to left in the figure.

[0046] In this configuration, D is gradually recovered in the recovered water from the final stage to the first stage, so the cell recovered water W0 K The D concentration increases from the final stage to the first stage. On the other hand, in order to increase the D recovery efficiency, the cell recovery water W0 K It is preferable that the D concentration in the water is low. With this configuration, even when water is circulated in this manner, the D concentration in the cell recovery water in most of cells 1 to N can be kept low, thereby improving the overall D recovery efficiency. Furthermore, when using multiple cells in this manner, flowing water in this manner can reduce the amount of water used for D recovery.

[0047] In the configuration of FIG. 4, the cathode side exhaust gas G2 in cell K K The cell input gas G0 in the next cell K+1 K+1 By doing so, the recovery efficiency of D was improved. On the other hand, in the deuterium recovery device 3 shown in FIG. 5, the cathode side exhaust gas G2 K As well as the anode side exhaust gas G1 K The cell input gas G0 in the next cell K+1 K+1 The water in Figure 5 (cell recovered water W0 K , Cell output water W1 K The flow of steps 1 and 2 is the same as that of Figure 4.

[0048] In this case, the anode side exhaust gas G1 in the cell K (K=1 to N-1) K Tank T K Introduced in the Tank T K Cathode side exhaust gas G2 introduced into K are mixed and the cell input gas G0 K+1The cell input gas G0 in cell K K In the exhaust gas, only the D component that is ionized by the first catalytic electrode 11 and flows to the cathode chamber 32 side is recovered through the reactions of the reaction formulas (1) and (2), and the D that is not ionized is recovered in the anode side exhaust gas G1 K In the configuration of Figure 4, this anode side exhaust gas G1 K In contrast, in the configuration of Figure 5, this anode side exhaust gas G1 K The D inside can also be recovered in cells K+1 and beyond.

[0049] In the configurations shown in Figures 4 and 5, the recovered water W0 is fed into the final cell N, and then flows sequentially to the first cell. However, although the amount of water used increases, the recovered water W0 K If all of these are independent and the recovered water has a D concentration of zero, the amount of D recovered can be maximized.

[0050] In Example 6, the configuration of Figure 4 was simplified to N = 2 (two stages), and the operating conditions of Cell 1 and Cell 2, input gas G0, and recovered water W0 were the same as in Example 5, resulting in α = 19. Here, the output water was the sum of cell output water W11 and cell output water W12. In other words, while the separation ability α of a single cell was 4.8, the separation ability α could be increased to 19 by using the configuration of Figure 4.

[0051] In Example 7, the configuration of FIG. 5 was simplified to N=2 (two stages), and the operating conditions of cells 1 and 2, the input gas G0, and the recovered water W0 were the same as in Example 5, resulting in α=17. In other words, this also enabled an increase in separation ability α. The reason why α in Example 7 was smaller than in the examples is thought to be because the raw material gas in the first stage was used, and it is expected that a higher α would be obtained if more stages were used.

[0052] In the above example, deuterium ( 2 H, D) is hydrogen ( 1 It has been shown that deuterium can be recovered from a gas mixture containing tritium (H, H). 3It is clear that hydrogen isotopes (H, T) can be recovered in a similar manner. The same is true for other hydrogen isotopes. [Explanation of symbols]

[0053] 1~3 Deuterium recovery device 10 Membrane electrode assembly (MEA) 11 First catalyst electrode 12 Second catalyst electrode 20 Proton Conducting Layer 31 Anode chamber 31A, 32A inlet 31B, 32B, 32C outlet 32 Cathode Chamber 40 Recovered water tank 41, T1~T N tank W water W0 Reclaimed water W1 Output Water

Claims

1. hydrogen( １ 1. A deuterium recovery apparatus for recovering deuterium from an input gas containing a mixture of hydrogen (H) and deuterium, an isotope of hydrogen, the apparatus comprising: a proton conducting layer made of a proton conductor that conducts positive hydrogen ions and having two opposing main surfaces; a first catalytic electrode formed on one of the main surfaces of the proton conducting layer and applied with a positive voltage; a second catalytic electrode formed on the other main surface of the proton conducting layer and having a negative voltage; a membrane electrode assembly having an anode chamber provided on the first catalytic electrode side so that the first catalytic electrode and the input gas come into contact with each other; a cathode chamber in which liquid water is stored so that the second catalytic electrode and liquid water are in contact with each other; the deuterium ions flowing from the anode chamber to the cathode chamber are subjected to a liquid-phase chemical exchange reaction with the water, and the recovered water is taken out from the cathode chamber; a plurality of cells each including the membrane electrode assembly, the anode chamber, and the cathode chamber are used in stages; the cells are connected so that the gas other than water after the reaction in the cathode chamber of the preceding cell is used as the input gas of the adjacent next cell; In the cell, the cathode chamber is configured to introduce recovered water, which is the water before the deuterium is recovered, and to discharge output water, which is the water after the deuterium has been recovered, 1. A deuterium recovery device, wherein the cells are connected so that the output water from the cell in the subsequent stage is used as the recovered water for the adjacent cell in the preceding stage.

2. 2. The deuterium recovery device according to claim 1, wherein the first catalytic electrode and the second catalytic electrode contain particles made of a noble metal selected from platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), and gold (Au), or an alloy containing the noble metal.

3. The deuterium is deuterium ( ２ H or D), or tritium ( ３ 3. The deuterium recovery device according to claim 1, wherein the deuterium recovery device is a deuterium recovery device.

4. hydrogen( １ 1. A deuterium recovery method for recovering deuterium from an input gas containing a mixture of hydrogen (H) and deuterium, an isotope of hydrogen, the method comprising: a proton conducting layer made of a proton conductor that conducts positive hydrogen ions and having two opposing main surfaces; a first catalytic electrode formed on one of the main surfaces of the proton conducting layer and applied with a positive voltage; a second catalytic electrode formed on the other main surface of the proton conducting layer and having a negative voltage; A membrane electrode assembly having applying a voltage to the first catalytic electrode at a positive potential and the second catalytic electrode at a negative potential in a state in which the first catalytic electrode and the input gas are in contact with each other and the second catalytic electrode is in contact with liquid water; the deuterium ions that have flowed from the first catalytic electrode side to the second catalytic electrode side are subjected to a liquid-phase chemical exchange reaction with the water, and the recovered water is extracted; a plurality of cells each having the membrane electrode assembly are used in stages; the cells are connected so that the gas other than water after the reaction on the second catalytic electrode side in the preceding cell is used as the input gas in the adjacent next cell; recovered water, which is the water before the deuterium has been recovered, is introduced to the second catalytic electrode side of the cell, and output water, which is the water after the deuterium has been recovered, is discharged; A method for recovering deuterium, comprising connecting the cells so that the output water from the cell in the subsequent stage is used as the recovered water from the adjacent cell in the preceding stage.

5. 5. The method for recovering heavy hydrogen according to claim 4, wherein the first catalytic electrode and the second catalytic electrode contain particles made of a noble metal selected from platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), and gold (Au), or an alloy containing the noble metal.

6. The deuterium is deuterium ( ２ H or D), or tritium ( ３ 6. The method for recovering deuterium according to claim 4, wherein the deuterium is H or T.

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