Deuterium recovery apparatus, deuterium recovery method

Abstract

Deuterium is recovered with high efficiency and low power consumption. [Solution] A DC voltage is applied between the first catalyst electrode 11 and the second catalyst electrode 12, with the first catalyst electrode 11 side being positive and the second catalyst electrode 12 side being negative. The first catalyst electrode 11 side is an anode chamber 31 to which deuterium (D) to be recovered is supplied as a gas along with hydrogen (H). The second catalyst electrode 12 side is a cathode chamber 32 in which water W, mainly composed of H2O, is stored in contact with the second catalyst electrode 12. H and D in the anode chamber 31 flow to the second catalyst electrode 12 side when a voltage is applied. Subsequently, through a reaction with water etc. in the cathode chamber 32, only the D component of H and D is preferentially incorporated into the water (liquid) in this chamber, and the H component is removed as a gas. In this way, D can be recovered into this water with high efficiency.

Description

[Technical Field]

[0001] This invention relates to hydrogen ( 1 This invention relates to a deuterium recovery apparatus and method for selectively recovering deuterium from a mixture of H and deuterium. [Background technology]

[0002] Hydrogen with a mass number of 1 (meaning its atomic nucleus consists of only one proton) is a stable isotope of hydrogen that makes up naturally occurring water and hydrogen gas. 1 H (hereinafter referred to as H) and deuterium, which has a mass number of 2 (its nucleus consists of one proton and one neutron). 2 There is also hydrogen (hereinafter referred to as D), and the abundance of D is overwhelmingly smaller than that of H. The chemical properties of H and D are almost the same, but in the fields of nuclear energy and semiconductor manufacturing, there are known applications where D is particularly effective. For this reason, there is a need for technology to selectively extract (separate) D from water or hydrogen gas in which H and D are present. However, since it is practically impossible to completely separate H and D instantaneously, in practice, treatment is performed on substances (water, hydrogen gas, etc.) in which they are present in order to increase the concentration of one of them (especially D) in order to separate them.

[0003] Since the chemical properties of H and D are almost identical, they are generally not easily separated by chemical methods, and various separation methods (or methods for concentrating D) are known. A technique is known to obtain a gas or liquid with a higher D concentration from a gas or liquid containing H and D using a membrane electrode assembly (MEA) having a catalyst / proton conducting layer / catalyst structure similar to those used in fuel cells. In a gas or liquid containing H and D, D exists in forms such as D2, HD (gas corresponding to H2), or HDO, D2O (liquid or gas corresponding to H2O).

[0004] In Patent Document 1, such a membrane electrode assembly is used, and at this time, a technique for increasing the D concentration by using the H-D exchange reaction (vapor-phase chemical exchange reaction: VPCE reaction) of hydrogen gas and water vapor on the catalyst is described. The VPCE reaction is represented by the following reaction formula (1).

[0005]

Number

[0006] Here, (g) indicates the gas phase. HD(g) on the left side is a component generated on the catalyst after permeating through the MEA supplied from the outside, and H2O(g) on the left side is a component (water vapor) supplied from the outside independently of HD(g). In reality, the reaction from the left side to the right side and the reaction from the right side to the left side in reaction formula (1) occur simultaneously to reach an equilibrium state.

[0007] The D in HDO(g) generated on the right side is the D in HD(g) on the left side, and this HDO(g) is generated by replacing one H in H2O(g) on the left side with D. On the other hand, the H in HD(g) on the left side combines with the H in H2O(g) where H has been replaced by D above on the right side to form H2(g), and is separated from D and released as a gas. Therefore, if the reaction from the left side to the right side in reaction formula (1) is dominant and reaches an equilibrium state, only the D component can be preferentially obtained by extracting HDO(g) from the input HD component. That is, D can be taken into and recovered from water vapor by using the above VPCE reaction.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] In the technology described in Patent Document 1, both HD(g) and H2O(g) on ​​the left side of equation (1) exist as gases on the catalyst. In particular, if H2O exists as a liquid on the catalyst, it will prevent the gaseous HD(g) from reaching the catalyst. Therefore, the H2O(g) used in this case must be in gaseous form, and for this, a mechanism is needed to constantly heat water and supply it as a gas (water vapor). Furthermore, this requires maintaining a high temperature of the membrane electrode assembly itself. For this reason, in the technology described in Patent Document 1, power consumption was high in order to obtain a high recovery rate.

[0010] Therefore, there was a need for a technology that could recover deuterium with high efficiency and low power consumption.

[0011] This invention has been made in view of the above-mentioned problems, and aims to provide an invention that solves the above-mentioned problems. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention has the following configuration. The deuterium recovery apparatus of the present invention uses hydrogen ( 1 A deuterium recovery apparatus for recovering deuterium from an input gas containing a mixture of H and deuterium, an isotope of hydrogen, the apparatus comprises a membrane electrode assembly having a proton conducting layer composed 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 such that the first catalytic electrode and the input gas are in contact, and a cathode chamber in which liquid water is stored such that the second catalytic electrode and liquid water are in contact, and the water recovered by a liquid-phase chemical exchange reaction between the deuterium that has flowed as ions from the anode chamber side to the cathode chamber side and the water is taken out from the cathode chamber. The first catalytic electrode and the second catalytic electrode may contain particles made of a precious metal, such as platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), or gold (Au), or an alloy containing such a precious metal. Multiple cells, each comprising the aforementioned membrane electrode assembly, the anode chamber, and the cathode chamber, may be used in a stepwise manner, and each cell may be connected such that the gas other than water after the reaction in the cathode chamber of the preceding cell is used as the input gas for the adjacent next cell. The anode chamber is configured to receive the input gas before the reaction and to discharge the input gas after the reaction in the preceding cell, and the cells may be connected in such a way that the input gas after the reaction in the preceding cell is used as the input gas for the adjacent next stage. In the cell, the cathode chamber is configured such that recovered water, which is the water before the deuterium is recovered, is introduced into it, and output water, which is the water after the deuterium has been recovered, is discharged from it. The cells may be connected in such a way that the output water in the subsequent cell is used as the recovered water in the adjacent preceding cell. The aforementioned deuterium is dutium ( 2 H or D), or tritium ( 3 H or T) is fine. The deuterium recovery method of the present invention involves hydrogen ( 1H) and deuterium, which is an isotope of hydrogen, are mixed in an input gas, and a method for recovering the deuterium from the input gas, comprising: a proton-conducting layer composed of a proton conductor that conducts positive ions of hydrogen, and having two opposing main surfaces; a first catalyst electrode formed on one of the main surfaces of the proton-conducting layer and having a positive-side voltage; and a second catalyst electrode formed on the other main surface of the proton-conducting layer and having a negative-side voltage. Using a membrane electrode assembly having these electrodes, the first catalyst electrode is brought into contact with the input gas, and the second catalyst electrode is brought into contact with liquid water. A voltage is applied such that the first catalyst electrode has a positive-side potential and the second catalyst electrode has a negative-side potential. The deuterium that has flowed as an ion from the first catalyst electrode side to the second catalyst electrode side is recovered by a liquid-phase chemical exchange reaction between the deuterium and the water, and the water thus recovered is taken out. The first catalyst electrode and the second catalyst electrode each contain particles made of a noble metal selected from platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), gold (Au), or an alloy containing the noble metal. A plurality of cells each having the membrane electrode assembly may be used in stages, and the cells may be connected such that a gas other than the water after the reaction on the second catalyst electrode side in the previous-stage cell is used as the input gas for the adjacent next-stage cell. The cells may be connected such that the input gas after the reaction in the previous-stage cell is used as the input gas for the adjacent next-stage cell. Recovery water, which is the water before recovering the deuterium, may be introduced to the second catalyst electrode side in the cell, and output water, which is the water after recovering the deuterium, may be discharged. The cells may be connected such that the output water in the subsequent-stage cell is used as the recovery water for the adjacent previous-stage cell. The deuterium may be deuterium 2 H or D), or tritium 3 H or T).

Advantages of the Invention

[0013] As described above, the present invention can recover deuterium with high efficiency and low power consumption. [Brief explanation of the drawing]

[0014] [Figure 1] This figure shows the configuration of a deuterium recovery apparatus according to an embodiment of the present invention. [Figure 2] These are the results of measuring the separation efficiency α in the examples and comparative examples of the present invention. [Figure 3] This figure shows the configuration of a first modified example of a deuterium recovery apparatus according to an embodiment of the present invention. [Figure 4] This figure shows the configuration of a second modified example of a deuterium recovery apparatus according to an embodiment of the present invention. [Figure 5] This figure shows the configuration of a third modified example of a deuterium recovery device according to an embodiment of the present invention. [Modes for carrying out the invention]

[0015] The following describes a deuterium recovery apparatus and deuterium recovery method according to embodiments of the present invention. This deuterium recovery apparatus and method selectively recovers D from an input gas (hydrogen gas) containing both H and D, and incorporates it into water for recovery. This makes it possible to obtain water with a high concentration of D, or to reduce the D concentration in the hydrogen gas.

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

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

[0018] The first catalytic electrode 11 and the second catalytic electrode 12 both utilize a precious metal (such as platinum (Pt)) that functions as a catalyst, in a form that balances both electrode and catalytic functions. 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 catalytic activity. In this case, the catalyst (Pt, etc.) content is 0.1 to 2.0 mg / cm³. 2 It is preferable to use a catalyst of a certain degree. Furthermore, the first catalyst electrode 11 is a catalyst material that oxidizes hydrogen isotopes, and the second catalyst electrode 12 is a catalyst material that efficiently causes the liquid-phase chemical exchange reaction described later. In addition to Pt, precious 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 precious metals), can be used for both.

[0019] In Figure 1, the proton conducting layer 20, the first catalytic electrode 11, and the second catalytic electrode 12 (MEA10) are shown as simple flat plates. However, by providing appropriate irregularities instead of making them flat, their surface area and contact area can be substantially increased. In this case as well, the operation described below is performed similarly, and by increasing these areas, the processing capacity can be improved.

[0020] The above configuration is the same as the technology described in Patent Document 1. On the other hand, in this deuterium recovery apparatus 1, the configuration of the side from which deuterium is recovered (cathode side: second catalyst electrode 12 side) differs significantly from the technology described in Patent Document 1.

[0021] In Figure 1, the side of the first catalyst electrode 11 is an anode chamber 31 to which hydrogen gas containing deuterium (D) to be recovered is supplied. The hydrogen gas introduced into this chamber is brought in through an inlet 31A and discharged through an outlet 31B. As a result, hydrogen gas (gas) containing H and D is accumulated in the anode chamber 31 in contact with the first catalyst electrode 11. The gas introduced into the inlet 31A may include not only hydrogen gas containing D, but also other gases that function as carrier gases (such as N2, Ar, O2, etc.).

[0022] In Figure 1, the side of the second catalyst electrode 12 is a cathode chamber 32 in which water W, mainly composed of H2O, is stored in contact with the second catalyst electrode 12. For this reason, the cathode chamber 32 is provided with an inlet 32A into which water is introduced and an outlet 32B from which water (liquid) is discharged. In addition, an outlet 32C for discharging gaseous components generated in the cathode chamber 32 is provided separately from the outlet 32B. However, outlets 32B and 32C may be formed as a common outlet from which the liquid and gas are separated and extracted.

[0023] In this deuterium recovery apparatus 1, H and D in the anode chamber 31 flow to the second catalyst electrode 12 side when a voltage is applied. Subsequently, through a reaction with water in the cathode chamber 32, only the D component of H and D is preferentially incorporated into the water (liquid) in this chamber, while the H component is removed as a gas. This allows for highly efficient recovery of D in this water.

[0024] Let's explain this principle. Here, H and D exist in the anode chamber 31 in the form of gases such as H2, D2, and HD. Similar to the technology described in Patent Document 1, these molecules are decomposed by the first catalytic electrode 11, and H and D become ions (positive ions). These ions flow through the proton conducting layer 20 to the right in the diagram and reach the second catalytic electrode 12, where the same gas as described above is generated again. Below, we will explain the behavior of HD, which is a molecule in which H and D are bonded. This HD is formed as a gas called HD(g), and similar to 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) was supplied from an external source, whereas in the configuration shown in Figure 1, water vapor is not supplied, and liquid water W(H2O(l)) is in direct contact with the second catalyst electrode 12. In reaction equation (1), HD(g) is generated and exists as small bubbles (nanobubbles) on the surface of the second catalyst electrode 12 in water. H2O(g) is supplied to these nanobubbles from the surrounding water, and this H2O(g) reacts with HD(g), causing the reaction in reaction equation (1). That is, as a result, of the HD(g) formed on the second catalyst electrode 12, D exists as HDO(g) and H exists as H2(g), both in water.

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

[0028]

number

[0029] Here, (l) indicates the liquid phase. The HDO(g) on ​​the left side is the same as the HDO(l) on the right side of reaction equation (1), and the H2O(l) is the water supplied from the inlet 32A in Figure 1. In this case, the HDO(g) and H2O(l) on the left side undergo a phase change to the HDO(l) and H2O(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 HDO(l) on the right side of reaction equation (2) incorporates the D from HD(g) on ​​the left side of reaction equation (1), while the H from HD(g) is removed as H2(g) on ​​the right side of reaction equation (1). Therefore, when equilibrium is reached with the reaction from the left side to the right side of reaction equation (2) being dominant, HDO(l) on the right side is produced, and this HDO(l) is obtained by removing the water after the reaction from outlet 32B. On the other hand, 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 uses reaction equation (2) as well to recover D in liquid (water) form.

[0031] Note that in reaction equation (1), D is assumed to exist 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 by D2(g), then H2(g) on ​​the right side is replaced by HD(g). In this case, this HD(g) becomes the HD(g) on ​​the left side of reaction equation (1), and ultimately, the reaction in reaction equation (1) is realized even in this case. That is, gas-phase chemical exchange reactions and liquid-phase chemical exchange reactions occur similarly with respect to D2.

[0032] We will now describe the results of measuring the recovery rate of D (separation efficiency relative to H) using the configuration shown in Figure 1. Here, the MEA used was the same for all examples and comparative examples. Nafion 212 (Chemours) was used as the proton conducting layer 20, and the first catalyst electrode 11 and the second catalyst electrode 12 both had a Pt particle concentration of 0.5 mg / cm³. 2 The aforementioned Pt / C electrode was used. The potential difference between the first catalyst electrode 11 and the second catalyst electrode 12 was set to approximately 0.01V. The reaction temperature was room temperature (23°C).

[0033] Here, as a comparative example, measurements were also performed 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 performed in examples in which the heavy water (D) concentration was varied for the water introduced into the cathode chamber 32. In this example, 4.5 sccm of H2 and 0.5 sccm of D2 (molar ratio of H / D = 9) were introduced into the inlet 31A. Here, mass gas analysis was performed 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 and HD in the gas was measured by mass gas analysis, and the H / D ratio R was calculated accordingly. 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 taken as R1, and the H / D ratio R of the latter as R2, and α = R2 / R1 was calculated. When α = 1 (R1 = R2), it means that the H / D ratio remains unchanged between the gas on the anode chamber 31 side (input side) and the cathode chamber 32 side (output side), and 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, it means that the D concentration in the gas in the cathode chamber 32 is decreasing, and conversely, the D concentration in the liquid is increasing. Therefore, the above α can be used as an indicator (separation ability) of the recovery rate of D.

[0035] In the comparative example, as described in Patent Document 1, both H2 (g) and HDO (g) on ​​the right-hand side of the above reaction equation (1) exist as gases in the cathode chamber 32. In this case as well, if the above reaction equation (1) is valid, H2 and HD are present in the gas, and the relationship between the H ratio of this gas and the D ratio in the water vapor at 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 indicator of the recovery rate.

[0036] Furthermore, as examples, four types of examples (Examples 1 to 4) were used in which the D concentration in the water (before reaction) introduced into the cathode chamber 32 was 0.015% (hereinafter referred to as 0%), 5%, 10%, and 20%. In this case, the absolute value of the D concentration in the liquid at the time of measurement differs greatly depending on the original D concentration, but in the evaluation using α described above, only the D newly incorporated into the liquid is evaluated, so the evaluation using α is effective in the same way.

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

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

[0039] Similarly, on the anode chamber 31 side, a gas containing H and D (input gas) is introduced into the inlet 31A, and the gas is 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] As Example 5, in the configuration shown in Figure 3, H2 is circulated at a flow rate of 5 sccm and D2 at a flow rate of 5 sccm on the anode chamber 31 side, water with a D concentration of 0% (same as Example 1) is used as the recovered water W0, the water flow rate is set to 0.02 ml / s, and the current density between the first catalyst electrode 11 and the second catalyst electrode 12 is set to 0.2 A / cm². 2 In this case, α = 4.8 was obtained.

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

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

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

[0044] In the configuration shown in Figure 4, the main input gas G0 from which D is to be recovered (removed) is the cell input gas G01 of the first stage cell 1. In addition, tank T is provided for each cell. K (K=1~N) contains the liquid component cell output water W1 from the cathode chamber 32. K and the gaseous component, cathode exhaust gas G2 K This will be introduced. Among these, the cathode side exhaust gas G2 in cell K K (K=1~N-1) is tank T K The cell input gas G0 in the next cell K+1 is transmitted via this. K+1 This results in the next cell K+1, where the cathode-side exhaust gas G2 K The remaining D inside is used in the cell output water W1 K+1 It can be recovered inside. In other words, with this configuration, D in the input gas W0 is collected by cells 1 to N, and the cell output water W1 K It can be recovered during (K=1~N). This increases the recovery efficiency of D. In this case, the cell input gas G0 K The concentration of D inside gradually decreases from the first stage to the final stage as D is recovered, and consequently, the cell output water W1 in each cell K The amount of D recovered also decreases from the first stage to the final stage. In addition, in the configuration shown in Figure 4, the anode-side exhaust gas G1 in each cell K (K=1~N), and the cathode-side exhaust gas G2 of the final stage. N It is discharged to the outside.

[0045] Furthermore, just as the gas to be recovered (D) is flowed between cells, in the configuration of Figure 4, the water used to recover D is also shared by flowing between cells. That is, tank T in cell K (K=2~N) K Internal cell output water W1 KThis refers to the cell recovery water W0 in the preceding cell K-1. K-1 This is the result. Also, the cell recovery water W0 in the final cell N N This results in recovered water W0 with a low D concentration (D concentration set to zero). In other words, the water flow is in the opposite direction to the gas flow mentioned above, from right to left in the diagram.

[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 concentration of D increases from the final stage to the first stage. On the other hand, in order to increase the recovery efficiency of D, the cell recovered water W0 K It is preferable that the concentration of D inside is low. With this configuration, even when the water is circulated in this way, the concentration of D in the recovered water in most of cells 1 to N can be kept low, and the overall D recovery efficiency can be increased. In addition, when using multiple cells in this way, the amount of water used for D recovery can be reduced by circulating the water in this manner.

[0047] In the configuration shown in Figure 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 increased. In contrast, in the deuterium recovery apparatus 3 shown in Figure 5, the cathode side exhaust gas G2 K In addition, anode side exhaust gas G1 K Also, the cell input gas G0 in the next stage cell K+1 K+1 It is said that the water (cell recovered water W0) in Figure 5 K Cell output water W1 K The flow of this process is the same as that shown in Figure 4.

[0048] In this case, the anode-side exhaust gas G1 in cell K (K=1~N-1) K Tank T K It was introduced to, and similarly to Tank T K Cathode exhaust gas G2 introduced K These are mixed, and the cell input gas G0 in the next stage cell K+1 K+1It is said that the cell input gas G0 in cell K K In this process, only component D, which is ionized by the first catalytic electrode 11 and flows to the cathode chamber 32, is recovered through the reaction shown in reaction equations (1) and (2), while the unionized D is recovered as anode exhaust gas G1. K It remains inside. In the configuration shown in Figure 4, this is the anode-side exhaust gas G1 K While the previous configuration in Figure 5 involved discarding the anode-side exhaust gas G1 K The D inside can also be recovered in cells K+1 and beyond.

[0049] In the configuration shown in Figures 4 and 5, the recovered water W0 is introduced into the final cell N, and this is then sequentially discharged to the first stage. However, although the amount of water used increases, the recovered water W0 K If we treat each of these as independent and consider the recovered water W0 as having a zero concentration of D in each case, we can maximize the amount of D recovered.

[0050] As Example 6, the configuration in Figure 4 was simplified to N=2 (2 stages), and when the operating conditions of cell 1 and cell 2, input gas G0, and recovered water W0 were the same as in Example 5, α=19 was obtained. Here, the output water was the sum of cell output water W11 and cell output water W12. In other words, while the separation capacity α of a single cell was 4.8, the configuration in Figure 4 was able to increase the separation capacity α to 19.

[0051] In Example 7, the configuration of Figure 5 was simplified to N=2 (2 stages), and when the operating conditions of cell 1 and cell 2, the input gas G0, and the recovered water W0 were the same as in Example 5, α=17 was obtained. In other words, the separation efficiency α could also be increased. The reason why α was smaller in Example 7 than in Example 5 is thought to be because the raw material gas is used in the first stage, and it is expected that a higher α can be obtained if more stages are used.

[0052] In the above example, deuterium ( 2 H, D) is hydrogen ( 1 It has been shown that the deuterium component can be recovered from a gas containing a mixture of H, H, but in principle, tritium ( 3It is clear that H and T) can be recovered in the same way. The same applies to other hydrogen isotopes. [Explanation of symbols]

[0053] 1-3 Deuterium recovery unit 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 tanks 41, T1~T N tank W water W0 Recovered Water W1 Output Water

Claims

1. hydrogen( １ A deuterium recovery apparatus for recovering deuterium from an input gas in which H) and deuterium, an isotope of hydrogen, are mixed, A proton conducting layer comprising a proton conductor that conducts positive hydrogen ions, and having two opposing main surfaces, A first catalyst electrode formed on one of the main surfaces of the proton conducting layer, which is set to the positive voltage, A second catalytic electrode, formed on the other main surface of the proton conducting layer and having a negative voltage, It comprises a membrane electrode assembly having, An anode chamber is provided on the first catalyst electrode side such that the first catalyst electrode and the input gas are in contact, The apparatus comprises a cathode chamber in which liquid water is stored so as to be in contact with the second catalytic electrode, A deuterium recovery apparatus characterized in that the water recovered by a liquid-phase chemical exchange reaction between the deuterium that has flowed as ions from the anode chamber to the cathode chamber and the water is removed from the cathode chamber.

2. The deuterium recovery apparatus according to claim 1, characterized in that the first catalytic electrode and the second catalytic electrode contain particles made of a precious metal, which is one of platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), or gold (Au), or an alloy containing such precious metal.

3. Multiple cells, each comprising the aforementioned membrane electrode assembly, the anode chamber, and the cathode chamber, are used in a stepwise manner. The deuterium recovery apparatus according to claim 1 or 2, characterized in that each cell is connected such that the gas other than water after the reaction in the cathode chamber of the preceding cell is used as the input gas for the adjacent next stage.

4. The anode chamber is configured such that the input gas before the reaction is introduced into it, and the input gas after the reaction in the preceding cell is discharged. The deuterium recovery apparatus according to claim 3, characterized in that each of the cells is connected such that the input gas after the reaction in the preceding cell is used as the input gas for the adjacent next cell.

5. In the cell, the cathode chamber is configured such that recovered water, which is the water before the deuterium is recovered, is introduced into it, and output water, which is the water after the deuterium has been recovered, is discharged from it. The deuterium recovery apparatus according to claim 3, characterized in that each cell is connected such that the output water in the subsequent cell is used as the recovered water in the adjacent preceding cell.

6. The aforementioned deuterium is dutium ( ２ H or D), or tritium ( ３ The deuterium recovery apparatus according to claim 1 or 2, characterized in that it is H or T.

7. hydrogen( １ A deuterium recovery method for recovering deuterium from an input gas in which H) and deuterium, an isotope of hydrogen, are mixed, A proton conducting layer composed of a proton conductor that conducts positive hydrogen ions, and having two opposing main surfaces, A first catalyst electrode formed on one of the main surfaces of the proton conducting layer, which is set to the positive voltage, A second catalytic electrode, formed on the other main surface of the proton conducting layer and having a negative voltage, Using a membrane electrode assembly having, With the first catalyst electrode in contact with the input gas and the second catalyst electrode in contact with liquid water, a voltage is applied with the first catalyst electrode having a positive field potential and the second catalyst electrode having a negative field potential. A method for recovering deuterium, characterized in that the deuterium that has flowed as ions from the first catalyst electrode side to the second catalyst electrode side is recovered by a liquid-phase chemical exchange reaction between the deuterium and the water, and the water is then extracted.

8. The deuterium recovery method according to claim 7, characterized in that the first catalytic electrode and the second catalytic electrode include particles made of a precious metal, which is one of platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rh), iridium (Ir), or gold (Au), or an alloy containing such precious metal.

9. Multiple cells, each comprising the aforementioned membrane electrode assembly, are used in a stepwise manner. The deuterium recovery method according to claim 7 or 8, characterized in that each cell is connected such that the gas other than water after the reaction on the second catalyst electrode side of the preceding cell is used as the input gas for the adjacent next stage.

10. The deuterium recovery method according to claim 9, characterized in that each of the cells is connected such that the input gas after the reaction in the preceding cell is used as the input gas for the adjacent next cell.

11. In the cell, the recovered water, which is the water before the deuterium is recovered, is introduced to the second catalyst electrode side, and the output water, which is the water after the deuterium has been recovered, is discharged. The deuterium recovery method according to claim 9, characterized in that each cell is connected such that the output water in the subsequent cell is used as the recovered water in the adjacent preceding cell.

12. The aforementioned deuterium is dutium ( ２ H or D), or tritium ( ３ The deuterium recovery method according to claim 7 or 8, characterized in that it is H or T.

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