WO2023093012A1 - Method for triple-electrode system electrolyzing water to produce hydrogen - Google Patents

Abstract

Provided in the present application is a method for a triple-electrode system electrolyzing water to produce hydrogen. The method comprises the following process: assembling an electrolytic cell; and forming a first circuit between a hydrogen evolution cathode plate, an auxiliary electrode plate and an external power source in the electrolytic cell, and also forming a second circuit between the auxiliary electrode plate, an oxygen evolution anode plate and the external power source, so as to enable, by means of the connection of the first circuit and the disconnection of the second circuit, a reaction on the hydrogen evolution cathode plate to prepare hydrogen, and enable, by means of the disconnection of the first circuit and the connection of the second circuit, a reaction on the oxygen evolution anode plate to prepare oxygen. In the same electrolytic cell, three electrodes, i.e. a hydrogen evolution cathode plate, an auxiliary electrode plate and an oxygen evolution anode plate, and an external power source are connected to form two circuits, such that separate preparation of hydrogen and oxygen is realized by means of controlling the connection and disconnection of the two circuits, and therefore the phenomenon of the mixture of prepared hydrogen and oxygen is avoided, thereby reducing the separation cost.

Description

A method for producing hydrogen by electrolyzing water with a three-electrode system

cross reference

This application claims the priority of the Chinese patent application filed with the State Intellectual Property Office of China on November 23, 2021, with the application number 202111394216.7, and the title of the invention is "A method for producing hydrogen by electrolysis of water with a three-electrode system", the entire content of which is incorporated by reference incorporated in this application.

technical field

The present application relates to the technical field of hydrogen production by electrolysis of water, in particular to a method for hydrogen production by electrolysis of water with a three-electrode system.

Background technique

The existing electrolyzer is a combination of many electrolytic chambers, and the main components of each electrolytic chamber are cathode, anode, diaphragm and electrolyte. Conventional water electrolysis technology generates hydrogen and oxygen at the cathode and anode during the electrode process, which will easily lead to the mixing of hydrogen and oxygen, making the prepared gas impure, and the subsequent purification will greatly increase the production cost. Using an ion-selective membrane to separate the hydrogen generated at the hydrogen evolution catalytic electrode and the oxygen generated at the oxygen evolution catalytic electrode is an effective solution, but the use of the ion-selective membrane also greatly increases the cost. In addition, due to the different kinetics of electrochemical hydrogen evolution and oxygen evolution, the rates of hydrogen and oxygen production are different. When the pressure on both sides of the ion-selective membrane is different, the loss of the membrane is also very serious, which further increases the cost. . In addition, the selective ion exchange membrane further increases the internal resistance of the electrolyzer and increases energy consumption. The current mainstream work is to improve or prepare a new type of diaphragm, in order to reduce the internal resistance while taking into account the hydrophilicity, ion permeability and the ability to completely separate hydrogen and oxygen. Although many new diaphragms have been researched and explored, the effect is still not very significant.

Contents of the invention

This application aims to solve one of the technical problems in the related art at least to a certain extent.

For this reason, the purpose of this application is to propose a method for producing hydrogen by electrolyzing water with a three-electrode system. The two circuits realize the separate preparation of hydrogen and oxygen by controlling the closing and opening of the two circuits, so that the prepared hydrogen and oxygen will not mix, simplify the separation cost, and the control method is simple and easy to operate.

In order to achieve the above purpose, a method for producing hydrogen by electrolyzing water with a three-electrode system proposed by the present application includes:

Assemble the electrolyzer;

A first circuit is formed between the hydrogen evolution cathode plate, the auxiliary electrode plate and the external power supply in the electrolytic cell, and a second circuit is formed between the auxiliary electrode plate, the oxygen evolution anode plate and the external power supply, so as to be closed by the first circuit and the second circuit is disconnected so that a reaction occurs on the hydrogen evolution cathode plate: H ₂ O+e ^- → 1/2H ₂ +OH ^- , hydrogen gas is prepared, and the first circuit is disconnected and the second Closing the circuit causes a reaction to occur on the oxygen evolution anode plate: OH ^- -e ^- → 1/4O ₂ +1/2H ₂ O, and oxygen is produced.

Further, the specific process of the assembled electrolyzer is as follows:

Fixing the hydrogen evolution cathode plate, auxiliary electrode plate and oxygen evolution anode plate on the cathode electrode frame, auxiliary electrode frame and anode electrode frame respectively;

Then, a retaining ring is sealed between the cathode electrode frame and the auxiliary electrode frame and between the auxiliary electrode frame and the anode electrode frame to obtain a three-electrode assembly.

Further, it also includes stacking a plurality of three-electrode assemblies sequentially in the order of the cathode electrode frame, the auxiliary electrode frame, and the anode electrode frame to form a three-electrode system.

Further, after passing through the end plate, insulating plate, cathode electrode frame in the three-electrode system, auxiliary electrode frame, anode electrode frame and retaining ring, insulating plate and end plate with the connecting rod in sequence, at both ends of the connecting rod The connecting nut is pressed on the two end pressure plates through the nut.

Further, it also includes the electrolysis cavity enclosed between the cathode electrode frame, the auxiliary electrode frame and the retaining ring, the auxiliary electrode frame, and the anode in each three-electrode assembly in the three-electrode system through the liquid flow holes on the end pressure plate and the insulating plate. Potassium hydroxide electrolyte is passed into the electrolytic cavity enclosed between the electrode frame and the guard ring.

Further, the hydrogen evolution cathode plate is one of nickel-based alloy hydrogen evolution electrode, porous nickel hydrogen evolution electrode, nickel-based noble metal oxide hydrogen evolution electrode and nickel-based dispersion composite hydrogen evolution electrode.

Further, the oxygen evolution anode plate is an alloy electrode with nickel, cobalt, and iron as effective catalytic components.

Further, the auxiliary electrode plate is a nickel hydroxide electrode. When the first circuit is closed and the second circuit is opened, a reaction occurs on the auxiliary electrode plate: Ni(OH) ₂ +OH ^- -e ^- →NiOOH+ _H2O ;

When the first circuit is disconnected and the second circuit is closed, a reaction occurs on the auxiliary electrode plate: NiOOH+H ₂ O+e ⁻ →Ni(OH) ₂ +OH ⁻ .

Further, the auxiliary electrode plate is an aluminum hydroxide electrode. When the first circuit is closed and the second circuit is opened, a reaction occurs on the auxiliary electrode plate: Al(OH) ₃ +OH ^- -e ^- → AlO(OH) ₂ +H ₂ O;

When the first circuit is disconnected and the second circuit is closed, a reaction occurs on the auxiliary electrode plate: AlO(OH) ₂ +H ₂ O+e ⁻ →Al(OH) ₃ +OH ⁻ .

Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.

Description of drawings

The above-mentioned and/or additional aspects and advantages of the present application will become apparent and easy to understand from the following description of the embodiments in conjunction with the accompanying drawings, wherein:

Fig. 1 is the flowchart of the method for hydrogen production by electrolysis of water with three-electrode system proposed by an embodiment of the present application;

Fig. 2 is the local structure schematic diagram of the electrolyzer of the present application;

Fig. 3 is the flow chart of the application's assembled electrolyzer;

Fig. 4 is the schematic diagram of the structure of the electrolytic chamber surrounded by the cathode electrode frame, the retainer and the auxiliary electrode frame provided with the auxiliary electrode plate in the present application;

Fig. 5 is a partial structural schematic diagram of Fig. 4 of the present application;

In the figure: 1, hydrogen evolution cathode plate; 2, auxiliary electrode plate; 3, oxygen evolution anode plate; 4, cathode electrode frame; 5, auxiliary electrode frame; 6, anode electrode frame; 7, retaining ring; 8, end pressure plate; 9. Insulation board.

Detailed ways

Embodiments of the present application are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary, are only for explaining the present application, and should not be construed as limiting the present application. On the contrary, the embodiments of the present application include all changes, modifications and equivalents falling within the spirit and scope of the appended claims.

Fig. 1 is a flow chart of a method for producing hydrogen by electrolyzing water with a three-electrode system proposed in an embodiment of the present application.

Referring to Figure 1 and Figure 2, a three-electrode system electrolysis of water hydrogen production method, including the following process:

Step 1: Assemble the electrolyzer;

Step 2: form the first circuit between the hydrogen evolution cathode plate 1, the auxiliary electrode plate 2 and the external power supply in the electrolytic cell, and simultaneously form the second circuit between the auxiliary electrode plate 2, the oxygen evolution anode plate 3 and the external power supply, so as to By closing the first circuit and disconnecting the second circuit, a reaction occurs on the hydrogen evolution cathode plate 1: H ₂ O+e ⁻ →1/2H ₂ +OH ⁻ , to prepare hydrogen;

Step 3: By opening the first circuit and closing the second circuit, a reaction occurs on the oxygen evolution anode plate 3: OH ^- -e ^- → 1/4O ₂ +1/2H ₂ O to prepare oxygen , in the same electrolytic cell, connect the three electrodes of the hydrogen evolution cathode plate 1, the auxiliary electrode plate 2 and the oxygen evolution anode plate 3 with the external power supply to form two circuits, and realize the hydrogen gas by controlling the closing and disconnection of the two circuits. The separate preparation of hydrogen and oxygen prevents the mixing of hydrogen and oxygen, which simplifies the cost of separation.

In detail, the hydrogen evolution cathode plate 1 is connected to the negative pole of the power supply, and the auxiliary electrode plate 2 is connected to the positive pole of the power supply. Hydrogen gas is prepared on the hydrogen evolution cathode plate 1 in the alkaline electrolyte, and the first circuit is electrolyzed in the alkaline electrolyte to obtain hydrogen gas. , when oxygen is produced, the auxiliary electrode plate 2 and the oxygen evolution anode plate 3 are electrolyzed to generate oxygen by opening the first circuit and closing the second circuit, that is to say, the auxiliary electrode plate 2 is connected to the negative pole of the power supply, and the oxygen evolution anode plate 3 is connected to The positive pole of the power supply is used to produce oxygen by electrolysis on the oxygen evolution anode plate 3 in the alkaline electrolyte. Since the oxygen evolution anode plate 3 is disconnected during the hydrogen production process, no oxygen will be generated. At the same time, the hydrogen evolution cathode plate 1 is in the process of preparing oxygen. In the off state, hydrogen will not be generated. Therefore, in the process of electrolyzing water, the separate preparation of hydrogen and oxygen can be realized by controlling the on-off of the first circuit and the second circuit. Not only is the operation simple, but also the oxygen and hydrogen are prepared separately, and no oxygen will appear. mixed with hydrogen.

3-5, in some embodiments, the specific process of assembling the electrolyzer is as follows:

Step 11: Fix the hydrogen evolution cathode plate 1, the auxiliary electrode plate 2 and the oxygen evolution anode plate 3 on the cathode electrode frame 4, the auxiliary electrode frame 5 and the anode electrode frame 6 respectively, that is to say, on the cathode electrode frame 4, the auxiliary electrode frame Installation holes are opened on frame 5 and anode electrode frame 6 respectively, and then hydrogen evolution cathode plate 1, auxiliary electrode plate 2 and oxygen evolution anode plate 3 are respectively installed on cathode electrode frame 4, auxiliary electrode frame 5 and anode electrode frame 6 in the hole;

Step 12: Then seal and install retaining rings 7 between the cathode electrode frame 4 and the auxiliary electrode frame 5 and between the auxiliary electrode frame 5 and the anode electrode frame 6 to obtain a three-electrode assembly.

In some embodiments, it also includes stacking a plurality of three-electrode assemblies sequentially in the order of the cathode electrode frame 4, the auxiliary electrode frame 5, and the anode electrode frame 6 to form a three-electrode system, specifically, each of the three-electrode assemblies Two adjacent electrode frames 5 are spaced by retaining rings 7, and two adjacent electrode frames between adjacent two three-electrode assemblies are also spaced and compressed by retaining rings 7, for example, there are two three-electrode assemblies At this time, the arrangement between the two three-electrode assemblies is cathode electrode frame 4-retaining ring 7-auxiliary electrode frame 5-retaining ring 7-anode electrode frame 6-retaining ring 7-pole electrode frame 4-retaining ring 7 - the structural arrangement of auxiliary electrode frame 5-retainer ring 7-anode electrode frame 6, in addition, the cathode electrode frame 4, auxiliary electrode frame 5 and retainer ring 7 form an electrolytic chamber, auxiliary electrode frame 5, anode electrode frame 6 The electrolytic chamber that is also surrounded by the retaining ring 7 can store electrolyte in the two electrolytic chambers, and because the retaining ring 7 and the electrode frame are sealed and connected, the electrolyte stored in the electrolytic chamber will not flow from the electrode The junction between the frame and the retaining ring 7 overflows, and because the material on the electrode plate is generally porous, the electrolyte can only flow between the electrolytic chambers through the porous structure on the electrode plate.

In some embodiments, connecting rods are used to sequentially pass through the end pressure plate 8, the insulating plate 9, the cathode electrode frame 4 in the three-electrode system, the auxiliary electrode frame 5, the anode electrode frame 6 and the retaining ring 7, the insulation plate 9 and the end pressure plate After 8, connect the nuts at both ends of the connecting rod, and press them on the two end pressure plates 8 through the nuts, so as to realize the compression and fixation between each electrolytic frame and the retaining ring in the three-electrode system, which can prevent the electrolyte from overflowing. When the connecting rod passes through the three-electrode system, taking two three-electrode assemblies as an example, the connecting rod passes through the cathode electrode frame 4-retaining ring 7-auxiliary electrode frame 5-retaining ring 7-anode electrode frame 6-retaining ring 7 - Pole electrode frame 4 - Guard ring 7 - Auxiliary electrode frame 5 - Guard ring 7 - Anode electrode frame 6.

In some embodiments, through the liquid passage holes on the end pressure plate 8 and the insulating plate 9, the electrolytic cavity enclosed between the cathode electrode frame 4, the auxiliary electrode frame 5 and the retaining ring 7 in each three-electrode assembly in the three-electrode system And the potassium hydroxide electrolyte is passed into the electrolytic cavity enclosed between the auxiliary electrode frame 5, the anode electrode frame 6 and the retaining ring 7, and then an environment for electrolysis is provided. In addition, on the end pressure plate 8 and the insulating plate 9, there are Gas flow hole, the oxygen or hydrogen generated in the electrolysis chamber flows out through the gas flow hole for collection, that is to say, a connected gas flow hole can be opened on one of the end pressure plates 8 and one of the insulating plates 9, so that the generated hydrogen gas Or oxygen flows out through the gas flow holes for collection. Since the generated oxygen or hydrogen may carry part of the electrolyte during the outflow process, the electrolyte may be lost. Therefore, one of the end pressure plates 8 and one of the insulating plates 9 Connected liquid flow holes are opened on the top, and then the electrolyte can be passed into the three-electrode assembly through the liquid flow holes, and the electrolyte can enter the electrolysis chamber through the pores of the porous material on the electrode plate of the three-electrode assembly to realize the Electrolyte stability.

In some embodiments, the hydrogen evolution cathode plate 1 can be one of nickel-based alloy hydrogen evolution electrode, porous nickel hydrogen evolution electrode, nickel-based noble metal oxide hydrogen evolution electrode and nickel-based dispersion composite hydrogen evolution electrode.

In addition, the oxygen evolution anode plate can be an alloy electrode with nickel, cobalt, and iron as effective catalytic components.

It should be explained in detail that there may be various types of auxiliary electrode plates 2 .

As a possible situation, the auxiliary electrode plate 2 may be a nickel hydroxide electrode. At this time, when the first circuit is closed and the second circuit is disconnected, a reaction occurs on the auxiliary electrode plate 2: Ni(OH) ₂ + OH ⁻ -e ⁻ →NiOOH+H ₂ O; when the first circuit is opened and the second circuit is closed, a reaction occurs on the auxiliary electrode plate 2: NiOOH+H ₂ O+e ⁻ →Ni(OH) ₂ +OH ⁻ .

As another possible situation, the auxiliary electrode plate 2 can be an aluminum hydroxide electrode. When the first circuit is closed and the second circuit is disconnected, a reaction occurs on the auxiliary electrode plate 2: Al(OH) ₃ +OH ^- -e ^- →AlO(OH) ₂ +H ₂ O; when the first circuit is opened and the second circuit is closed, a reaction occurs on the auxiliary electrode plate 2: AlO(OH) ₂ +H ₂ O+e ^- →Al(OH) ₃ + OH ^- .

It should be noted that, in the description of the present application, terms such as "first" and "second" are used for description purposes only, and should not be understood as indicating or implying relative importance. In addition, in the description of the present application, unless otherwise specified, "plurality" means two or more.

Any process or method descriptions in flowcharts or otherwise described herein may be understood to represent modules, segments or portions of code comprising one or more executable instructions for implementing specific logical functions or steps of the process , and the scope of alternative embodiments of the present application includes additional implementations in which functions may be performed out of the order shown or discussed, including substantially concurrently or in reverse order depending upon the functions involved, which It should be understood by those skilled in the art to which the embodiments of the present application belong.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limitations on the present application, and those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (9)

1. A method for producing hydrogen by electrolyzing water with a three-electrode system, characterized in that it comprises:

   Assemble the electrolyzer;

   A first circuit is formed between the hydrogen evolution cathode plate, the auxiliary electrode plate and the external power supply in the electrolytic cell, and a second circuit is formed between the auxiliary electrode plate, the oxygen evolution anode plate and the external power supply, so as to be closed by the first circuit and the second circuit is disconnected so that a reaction occurs on the hydrogen evolution cathode plate: H ₂ O+e ^- → 1/2H ₂ +OH ^- , hydrogen gas is prepared, and the first circuit is disconnected and the second Closing the circuit causes a reaction to occur on the oxygen evolution anode plate: OH ^- -e ^- → 1/4O ₂ +1/2H ₂ O, and oxygen is produced.
2. The method for producing hydrogen by electrolyzing water with a three-electrode system according to claim 1, wherein the specific process of assembling the electrolyzer is as follows:

   Fixing the hydrogen evolution cathode plate, auxiliary electrode plate and oxygen evolution anode plate on the cathode electrode frame, auxiliary electrode frame and anode electrode frame respectively;

   Then, a retaining ring is sealed between the cathode electrode frame and the auxiliary electrode frame and between the auxiliary electrode frame and the anode electrode frame to obtain a three-electrode assembly.
3. The method for producing hydrogen by electrolyzing water with a three-electrode system according to claim 2, further comprising stacking a plurality of three-electrode assemblies sequentially in the order of a cathode electrode frame, an auxiliary electrode frame, and an anode electrode frame to form a three-electrode system.
4. The method for producing hydrogen by electrolyzing water with a three-electrode system according to claim 3, further comprising:

   Use the connecting rod to pass through the end pressure plate, insulating plate, cathode electrode frame, auxiliary electrode frame, anode electrode frame and retaining ring, insulating plate and end pressure plate in the three-electrode system in sequence, and connect nuts at both ends of the connecting rod, and pass the nut Compressed on both end platens.
5. The method for producing hydrogen by electrolysis of water in a three-electrode system according to claim 4, further comprising feeding the cathode electrode frame and the auxiliary electrode in each three-electrode assembly in the three-electrode system through the liquid flow holes on the end pressure plate and the insulating plate Potassium hydroxide electrolyte is passed into the electrolytic cavity enclosed between the frame and the retaining ring and the electrolytic cavity enclosed between the auxiliary electrode frame, the anode electrode frame and the retaining ring.
6. The method for producing hydrogen by electrolyzing water with a three-electrode system according to claim 1, wherein the hydrogen-evolving cathode plate is a nickel-based alloy-based hydrogen-evolving electrode, a porous nickel-based hydrogen-evolving electrode, a nickel-based noble metal oxide-based hydrogen-evolving electrode, and a nickel-based One of the hydrogen evolution electrodes of the dispersion composite system.
7. The method for producing hydrogen by electrolyzing water with a three-electrode system according to claim 1, wherein the oxygen-evolving anode plate is an alloy electrode in which nickel, cobalt, and iron are effective catalytic components.
8. The method for producing hydrogen by electrolyzing water with a three-electrode system according to claim 1, wherein the auxiliary electrode plate is a nickel hydroxide electrode, and when the first circuit is closed and the second circuit is disconnected, the auxiliary electrode plate A reaction occurs on the electrode plate: Ni(OH) ₂ +OH ^- -e ^- →NiOOH+H ₂ O;

   When the first circuit is disconnected and the second circuit is closed, a reaction occurs on the auxiliary electrode plate: NiOOH+H ₂ O+e ⁻ →Ni(OH) ₂ +OH ⁻ .
9. The method for producing hydrogen by electrolyzing water with a three-electrode system according to claim 1, wherein the auxiliary electrode plate is an aluminum hydroxide electrode, and when the first circuit is closed and the second circuit is disconnected, the auxiliary A reaction occurs on the electrode plate: Al(OH) ₃ +OH ^- -e ^- →AlO(OH) ₂ +H ₂ O;

   When the first circuit is disconnected and the second circuit is closed, a reaction occurs on the auxiliary electrode plate: AlO(OH) ₂ +H ₂ O+e ⁻ →Al(OH) ₃ +OH ⁻ .

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