Device and method for separating hydrogen isotopes from PEM electrolyzed water with bipolar water supply

Abstract

The invention discloses a device and method for separating hydrogen isotopes from bipolar water supply PEM electrolyzed water. The device comprises an electrolytic bath, the electrolytic bath is provided with an anode and a cathode, the upper end of the anode is connected with a water isotope storage chamber, the water isotope storage chamber is connected with a first water pump, and the first water pump is connected with the lower end of the anode; the upper end of the cathode is connected with a cathode water storage chamber which is connected with a second water pump, and the second water pump is connected with the lower end of the stack cathode. Compared with a PEM electrolyzed water hydrogen isotope separation device with single-pole water supply, the PEM electrolyzed water hydrogen isotope separation device has the advantage that the separation factor can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalysis, and particularly to an apparatus and method for separating hydrogen isotopes by PEM electrolyzed water with bipolar water supply. Background Art

[0002] The separation factor is an important parameter for measuring the isotope separation effect. A high separation factor can not only reduce the number of multi-stage cycles in the separation process, but also save energy consumption and improve production efficiency. Therefore, a high separation factor has become one of the pursuits in the hydrogen isotope separation process. Among these hydrogen isotope separation methods such as cryogenic distillation method, Girdler sulfide method, quantum sieving method, thermal diffusion method, chromatography method, and metal hydride absorption method, except for the quantum sieving method, the other separation factors are generally low. However, the quantum sieving method also requires low temperature conditions and it is currently difficult to achieve industrial-scale applications. Electrolyzed water for separating hydrogen isotopes is a hydrogen isotope separation process with great industrial promise because of its large scale potential, clean sustainability, high separation factor, and mild temperature conditions. However, there is a risk of hydrogen-oxygen mixing in the traditional electrolyzed water separation process.

[0003] Due to its advantages such as large current density, high hydrogen purity, fast response speed, safety, low energy consumption, and large operation flexibility, PEM electrolyzed water technology has been widely studied, and PEM electrolyzed water for separating hydrogen isotopes has once again come into people's view.

[0004] For PEM electrolyzed water to separate hydrogen isotopes, since water molecules undergo an oxidation reaction on the anode side, losing electrons to generate oxygen and H + / D + . Subsequently, H + / D + under the action of an electric field, is conducted through the proton exchange membrane to the cathode to undergo a reduction reaction to generate hydrogen. Therefore, this apparatus can effectively avoid the safety problems caused by hydrogen-oxygen mixing and at the same time has the advantages of traditional electrolyzed water for separating hydrogen isotopes. However, the separation factor of the PEM electrolyzed water device for separating hydrogen isotopes with single-pole water supply has not been significantly improved compared with the device for traditional electrolyzed water to separate hydrogen isotopes.

[0005] Therefore, there is an urgent need to find a separation method with a high separation factor, large scale potential, and mild separation conditions. Summary of the Invention

[0006] The present invention aims to solve the problem of low current isotope separation factor and provides an apparatus and method for separating hydrogen isotopes by PEM electrolyzed water with bipolar water supply.

[0007] In order to achieve the above technical objectives, the technical solutions provided by the present invention are as follows:

[0008] A device for separating hydrogen isotopes by PEM electrolysis of water with bipolar water supply, comprising an electrolytic cell, the electrolytic cell is provided with an anode and a cathode, the upper end of the anode is connected to a water isotope storage chamber, the water isotope storage chamber is connected to a first water pump, and the first water pump is connected to the lower end of the anode; the upper end of the cathode is connected to a cathode water storage chamber, the cathode water storage chamber is connected to a second water pump, and the second water pump is connected to the lower end of the cathode of the stack.

[0009] Specifically, the water isotope storage chamber is used to store water isotope 7, the water isotope contains two or more of hydrogen isotopes protium, deuterium, and tritium, and the content is 0% to 99%; the cathode water storage chamber is used to store cathode water 8, the cathode water contains two or more of hydrogen isotopes protium, deuterium, and tritium, and the content is 0% to 99%.

[0010] Furthermore, the device for separating hydrogen isotopes by PEM electrolysis of water with bipolar water supply is a device that can simultaneously achieve bipolar water supply for both the anode and the cathode, and the hydrogen isotope gas and oxygen generated on both sides of the anode and the cathode do not converge.

[0011] Furthermore, the water isotope storage chamber is provided with an oxygen outlet.

[0012] Furthermore, the cathode water storage chamber is provided with a hydrogen isotope gas outlet, and the hydrogen isotope gas outlet can be connected to an isotope detection device for detecting the content of hydrogen isotope gas.

[0013] The present invention also provides a method for separating hydrogen isotopes by PEM electrolysis of water, comprising the following steps:

[0014] Step 1: Mix an anode catalyst, Nafion solution, isopropanol, and water in a certain proportion and ultrasonically disperse them to obtain an anode solution;

[0015] Step 2: Mix a cathode catalyst, Nafion solution, isopropanol, and water in a certain proportion and ultrasonically disperse them to obtain a cathode solution;

[0016] Step 3: Spray the anode solution described in Step 1 and the cathode solution described in Step 2 on both sides of a proton exchange membrane respectively to prepare a membrane electrode; then assemble the membrane electrode with an end plate, an insulating layer, an electrode plate, a bipolar plate, a gasket, and a diffusion layer into an electrolytic cell, and the electrolytic cell can be assembled by existing assembly methods;

[0017] Step 4: Connect the electrolytic cell, the water isotope storage chamber, the first water pump, the cathode water storage chamber, and the second water pump as described in Claim 1;

[0018] Step 5: Electrolytically separate the water isotope after powering on using the above device.

[0019] Furthermore, in Step 1, the anode catalyst is one or several of WO3, RuO2, Co3O4, MnO2, Ir, Ru, RuO2, or IrO2.

[0020] Further, in the anolyte, the volume ratio of isopropanol to water is 1:0.1 - 10, and the weight percentage of Nafion to the anode catalyst is 5w% - 60w%.

[0021] Further, in step 2, the cathode catalyst is one or more of MoS2, WS2, Pd / C, Mo2C, Ag, iron phosphide, nickel phosphide, cobalt phosphide, Pt or Pt / C.

[0022] Further, in step 3, the proton exchange membrane is one or more of proton exchange membranes with sulfonic acid groups or phosphoric acid groups, and the loading amount of the anode catalyst is 0.05 mg / cm 2 ~20 mg / cm 2 , and the loading amount of the cathode catalyst is 0.01 mg / cm 2 ~20 mg / cm 2 .

[0023] Further, in step 3, the electrolytic cell may include one chamber or multiple chambers.

[0024] Further, in step 5, the energizing current is 0.1 - 5 A / cm 2 .

[0025] The present invention has the following beneficial effects:

[0026] 1. Compared with the PEM electrolytic water separation hydrogen isotope device with single - pole water supply, this device increases the exchange reaction between the cathode water and the hydrogen atoms adsorbed on the catalyst surface, which can effectively improve the separation factor, reduce energy consumption and the scale of equipment.

[0027] 2. The stability of the anode and cathode catalysts of the membrane electrode of the present invention is one of the important parameters of this invention. The adopted anode and cathode catalysts have high stability, and their performance hardly decays after a long - term electrolysis reaction, having high industrial application value. Description of the Drawings

[0028] Figure 1 is a schematic diagram of the device;

[0029] Figure 2 is a graph of the stability test results;

[0030] Figure 1 In it: 1 - electrolytic cell, 2 - first water pump, 21 - second water pump, 3 - water isotope water storage chamber, 31 - cathode water storage chamber, 4 - gas - liquid conduit, 5 - anode, 6 - cathode, 7 - water isotope, 8 - cathode water, 9 - oxygen outlet, 10 - hydrogen isotope gas outlet. Detailed Embodiments

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] Glossary:

[0034] Separation factor: It represents the degree of separation of two substances by a certain unit separation operation or a certain separation process, generally denoted by α. In the process of electrolyzing water to separate hydrogen isotopes, its separation factor α is defined as:

[0035]

[0036] In the formula, "gas" is the hydrogen gas evolved, "liq" is the feed water before electrolysis, and [D] and [H] are the atomic fractions of D and H in the feed water and the evolved gas, respectively.

[0037] PEM electrolysis of water: PEM is the English abbreviation of Proton Exchange Membrane. In PEM electrolysis of water, at a certain voltage, water molecules are first decomposed into oxygen and hydrogen positive ions (H+) under the catalysis of the anode catalyst. Subsequently, H+ passes through the proton exchange membrane and is catalyzed by the cathode catalyst to generate hydrogen gas. Since the hydrogen gas generated at the cathode and the oxygen gas generated at the anode are separated by the PEM membrane, the hydrogen production purity of this method is relatively high.

[0038] OER: The English abbreviation of Oxygen Evolution Reaction.

[0039] HER: The English abbreviation of Hydrogen Evolution Reaction.

[0040] Example 1

[0041] Isopropanol and deionized water were mixed at a volume ratio of 1:2, and then IrO2 powder was added. Then, Nafion solution was added until the weight percentage of Nafion to IrO2 was 33 w%, and the anode solution was prepared after ultrasonic dispersion.

[0042] Deionized water and isopropanol were mixed at a volume ratio of 1:3, and then Pt / C powder was added. Then, Nafion solution was added until the weight percentage of Nafion to Pt / C was 20 w%, and the cathode solution was prepared after ultrasonic dispersion.

[0043] The anolyte and catholyte were respectively sprayed on both sides of the Nafion 115 proton exchange membrane by an ultrasonic spraying machine to prepare a membrane electrode with an IrO₂ loading of 1.6 mg / cm 2 and a Pt loading of 0.5 mg / cm 2 on the cathode side.

[0044] After assembling the end plates, insulating layers, electrode plates, bipolar plates, gaskets, diffusion layers, membrane electrodes, etc. into Figure 1 the electrolytic cell 1 as shown, water isotope with a deuterium content of 1% and catholyte water with a deuterium content of 0.015% were prepared. Then, according to Figure 1 the sequence shown, each device was connected through the gas-liquid conduit 4. The first water pump 2 and the second water pump 21 were turned on, and the current of the membrane electrode was controlled at 1 A / cm 2 . After the electrolysis was stable, the hydrogen isotope content was detected, and the obtained separation factor α was 21.4.

[0045] Example 2

[0046] Isopropanol and deionized water were mixed at a volume ratio of 1:2, and WO₃ powder was added. Then, Nafion solution was added until the weight percentage of Nafion to WO₃ was 5 w%. After ultrasonic dispersion, the anolyte was prepared.

[0047] Deionized water and isopropanol were mixed at a volume ratio of 1:1, and MoS₂ powder was added. Then, Nafion solution was added until the weight percentage of Nafion to MoS₂ was 10 w%. After ultrasonic dispersion, the catholyte was prepared.

[0048] The anolyte and catholyte were respectively sprayed on both sides of the Nafion 115 proton exchange membrane by an ultrasonic spraying machine to prepare a membrane electrode with a WO₃ loading of 0.5 mg / cm 2 and a MoS₂ loading of 0.1 mg / cm 2 on the cathode side.

[0049] After assembling the end plates, insulating layers, electrode plates, bipolar plates, gaskets, diffusion layers, membrane electrodes, etc. into Figure 1 the electrolytic cell 1 as shown, water isotope with a deuterium content of 1% and catholyte water with a deuterium content of 0.015% were configured. Then, according to Figure 1 the sequence shown, each device was connected through the gas-liquid conduit. The first water pump 2 and the second water pump 21 were turned on, and the current of the membrane electrode was controlled at 0.6 A / cm 2 . After the electrolysis was stable, the hydrogen isotope content was detected, and the obtained separation factor α was 15.1.

[0050] Example 3

[0051] Isopropanol and deionized water were mixed at a volume ratio of 1:1, and then RuO2 powder was added. Subsequently, Nafion solution was added until the weight percentage of Nafion to RuO2 was 60 w%, and the anolyte was prepared by ultrasonic dispersion.

[0052] Deionized water and isopropanol were mixed at a volume ratio of 1:10, and then Mo2C powder was added. Subsequently, Nafion solution was added until the weight percentage of Nafion to Mo2C was 80 w%, and the catholyte was prepared by ultrasonic dispersion.

[0053] The anolyte and catholyte were respectively sprayed on both sides of the Nafion 115 proton exchange membrane by an ultrasonic spraying machine, and a membrane electrode with an anodic RuO2 loading of 5 mg / cm 2 and a cathodic Mo2C loading of 2 mg / cm 2 was obtained.

[0054] The end plate, insulation layer, electrode plate, bipolar plate, gasket, diffusion layer, membrane electrode, etc. were assembled into Figure 1 the electrolytic cell 1 as shown. Then, water isotope with a deuterium content of 1% and cathodic water with a deuterium content of 0.015% were prepared. Subsequently, each device was connected in the order shown through the gas-liquid conduit, the first water pump 2 and the second water pump 21 were turned on, and the current of the membrane electrode was controlled at 0.4 A / cm Figure 2 as shown. After the electrolysis was stable, the hydrogen isotope content was detected, and the obtained separation factor α was 21.2. 2

[0055] Example 4

[0056] Isopropanol and deionized water were mixed at a volume ratio of 1:2, and then Co3O4IrO2 powder was added. Subsequently, Nafion solution was added until the weight percentage of Nafion to Co3O4 was 25 w%, and the anolyte was prepared by ultrasonic dispersion.

[0057] Deionized water and isopropanol were mixed at a volume ratio of 1:3, and then Pd / C powder was added. Subsequently, Nafion solution was added until the weight percentage of Nafion to Pd / C was 40 w%, and the catholyte was prepared by ultrasonic dispersion.

[0058] The anolyte and catholyte were respectively sprayed on both sides of the Nafion212 proton exchange membrane by an ultrasonic spraying machine, and a membrane electrode with an anodic Co3O4 loading of 1.6 mg / cm 2 and a cathodic Pd / C loading of 0.5 mg / cm 2 was obtained.

[0059] The end plate, insulation layer, electrode plate, bipolar plate, gasket, diffusion layer, membrane electrode, etc. were assembled into Figure 1 the electrolytic cell 1 as shown. Then, water isotope with a deuterium content of 1% and cathodic water with a deuterium content of 0.015% were prepared. Subsequently, each device was connected in the order shown through the gas-liquid conduitFigure 2 Link the devices in the shown order, turn on the first water pump 2 and the second water pump 21, and control the membrane electrode current at 0.4 A / cm 2 . After the electrolysis is stable, detect the hydrogen isotope content, and the obtained separation factor α is 21.3.

[0060] Example 5

[0061] Mix isopropanol and deionized water at a volume ratio of 1:10, add RuO2 powder, and then add Nafion solution until the weight percentage of Nafion to RuO2 is 33 w%, and prepare the anode solution after ultrasonic dispersion.

[0062] Mix deionized water and isopropanol at a volume ratio of 1:3, add WS2 powder, and then add Nafion solution until the weight percentage of Nafion to WS2 is 20 w%, and prepare the cathode solution after ultrasonic dispersion.

[0063] Spray the anode solution and the cathode solution on both sides of the Nafion 117 proton exchange membrane with an ultrasonic spraying machine respectively, and prepare a membrane electrode with an anode RuO2 loading of 1.6 mg / cm 2 and a cathode WS2 loading of 0.5 mg / cm 2 .

[0064] Assemble the end plate, insulating layer, electrode plate, bipolar plate, gasket, diffusion layer, membrane electrode, etc. into Figure 1 the electrolytic cell 1 shown, configure the water isotope with a deuterium content of 1% and the cathode water with a deuterium content of 0.015%. Then, according to the Figure 2 shown order, link the devices, turn on the first water pump 2 and the second water pump 21, and control the membrane electrode current at 2 A / cm 2 . After the electrolysis is stable, detect the hydrogen isotope content, and the obtained separation factor α is 25.

[0065] Comparative Example

[0066] Mix isopropanol and deionized water at a volume ratio of 1:2, add IrO2 powder, and then add Nafion solution until the weight percentage of Nafion to IrO2 is 33 w%, and prepare the anode solution after ultrasonic dispersion.

[0067] Mix deionized water and isopropanol at a volume ratio of 1:3, add Pt / C powder, and then add Nafion solution until the weight percentage of Nafion to Pt / C is 20 w%, and prepare the cathode solution after ultrasonic dispersion.

[0068] Spray the anode solution and the cathode solution on both sides of the Nafion 115 proton exchange membrane with an ultrasonic spraying machine respectively, and prepare a membrane electrode with an anode IrO2 loading of 1.6 mg / cm 2The membrane electrode with a cathode Pt loading of 0.5 mg / cm 2 .

[0069] After assembling the end plate, insulating layer, electrode plate, bipolar plate, gasket, diffusion layer, membrane electrode, etc. into the electrolytic cell 1 shown in Figure 1 , prepare the water isotope with a deuterium content of 1%. Then connect each device in the order of single-stage water supply through the gas-liquid conduit, turn on the water pump, and control the membrane electrode current at 0.4 A / cm 2 . After the electrolysis is stable, detect the hydrogen isotope content, and the obtained separation factor α is 3.6.

[0070] The experimental stability data is as shown in Figure 2 : During the long-term electrolysis process of 580 hours, it is found through the fresh water stability test experiment in the last 120 hours that there is almost no attenuation.

[0071] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0072] The above specific embodiments are detailed descriptions of the present invention. It cannot be determined that the specific embodiments of the present invention are only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions and substitutions can still be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. A device for separating hydrogen isotopes by PEM electrolyzed water with bipolar water supply, characterized in that, It includes an electrolytic cell (1), the electrolytic cell (1) is provided with an anode (5) and a cathode (6), the upper end of the anode (5) is connected to a water isotope water storage chamber (3), the water isotope water storage chamber (3) is connected to a first water pump (2), and the first water pump (2) is connected to the lower end of the anode (5); the upper end of the cathode (6) is connected to a cathode water storage chamber (31), the cathode water storage chamber (31) is connected to a second water pump (21), and the second water pump (21) is connected to the lower end of the cathode of the electrolytic cell (1).

2. The device for separating hydrogen isotopes by PEM electrolyzed water with bipolar water supply according to claim 1, characterized in that, The water isotope water storage chamber (3) is provided with an oxygen outlet (9).

3. The device for separating hydrogen isotopes by PEM electrolyzed water with bipolar water supply according to claim 1, characterized in that, The cathode water storage chamber (31) is provided with a hydrogen isotope gas outlet (10).

4. A method for separating hydrogen isotopes by PEM electrolysis of water with bipolar water supply, characterized in that, It includes the following steps: Step 1: Mix an anode catalyst, Nafion solution, isopropanol and water in a certain proportion and ultrasonically disperse them to obtain an anode solution; Step 2: Mix a cathode catalyst, Nafion solution, isopropanol and water in a certain proportion and ultrasonically disperse them to obtain a cathode solution; Step 3: Spray the anode solution in Step 1 and the cathode solution in Step 2 on both sides of a proton exchange membrane to prepare a membrane electrode; then assemble the membrane electrode with an end plate, an insulating layer, an electrode plate, a bipolar plate, a gasket, and a diffusion layer into an electrolytic cell; Step 4: Connect the electrolytic cell, the water isotope water storage chamber, the first water pump, the cathode water storage chamber, and the second water pump as described in Claim 1; Step 5: Electrolytically separate the water isotope after energizing the device according to any one of Claims 1-3.

5. A method for separating hydrogen isotopes by PEM electrolysis of water with bipolar water supply according to claim 4, characterized in that, In Step 1, the anode catalyst is one or several of WO3, RuO2, Co3O4, MnO2, Ir, Ru, RuO2 or IrO2.

6. The method for separating hydrogen isotopes by PEM electrolysis of water with bipolar water supply according to claim 4, characterized in that, In the anode solution, the volume ratio of isopropanol to water is 1:0.1 to 10, and the weight percentage of Nafion to the anode catalyst is 5 w% to 60 w%.

7. A method for separating hydrogen isotopes by PEM electrolysis of water with bipolar water supply according to claim 4, characterized in that, In Step 2, the cathode catalyst is one or several of MoS2, WS2, Pd / C, Mo2C, Ag, iron phosphide, nickel phosphide, cobalt phosphide, Pt or Pt / C.

8. A method for separating hydrogen isotopes by PEM electrolysis of water with bipolar water supply according to claim 4, characterized in that, In Step 3, the proton exchange membrane is one or several of proton exchange membranes with sulfonic acid groups or phosphoric acid groups, and the loading amount of the anode catalyst is 0.01 mg / cm 2 ~20 mg / cm 2 , and the loading amount of the cathode catalyst is 0.01 mg / cm 2 ~20 mg / cm 2 .

9. A method for separating hydrogen isotopes by PEM electrolysis of water with bipolar water supply according to claim 4, characterized in that, In Step 3, the electrolytic cell includes one or more small chambers.

10. The method for separating hydrogen isotopes by PEM electrolysis of water with bipolar water supply according to claim 4, wherein, In step 5, the energizing current is 0.1 to 5 A / cm 2 .

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