Alkaline solution for producing hydrogen by alkaline water electrolysis, preparation method thereof, alkaline water electrolysis hydrogen production system and application thereof

Abstract

The present invention provides an alkali solution for producing hydrogen by alkaline water electrolysis, comprising potassium hydroxide, sodium hydroxide and deionized water; the mass fraction of potassium hydroxide in the alkali solution is 20-40%, and the mass fraction of sodium hydroxide is 1-40%. Under the condition of not changing the concentration of KOH, the present invention adds sodium hydroxide to the alkali solution to increase the ion concentration in the solution, improve the solution conductivity, and reduce the solution resistance, thereby reducing the working temperature of electrolytic hydrogen production and reducing the energy consumption of hydrogen production. Compared with the prior art, the alkali solution for producing hydrogen by alkaline water electrolysis and the preparation method of the present invention have the following benefits: 1) improve the solution conductivity, reduce the solution resistance, and reduce the operating temperature of the alkaline water hydrogen production electrolyzer; 2) reduce the energy consumption of hydrogen production in the alkaline water hydrogen production electrolyzer; 3) the preparation method is simple, safe and reliable. The present invention also provides a preparation method of alkali solution for producing hydrogen by alkaline water electrolysis, an alkaline water electrolysis hydrogen production system and application.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen production by alkaline water electrolysis, and in particular relates to an alkali solution for hydrogen production by alkaline water electrolysis, a preparation method thereof, an alkaline water electrolysis hydrogen production system and applications. Background Art

[0002] The alkaline water electrolysis technology is the most mature, the lowest cost, and the most economical. Under the action of direct current, the alkaline water electrolysis technology electrolyzes water into hydrogen and oxygen. At the cathode, water molecules are decomposed into hydrogen ions and hydroxide ions. Hydrogen ions gain electrons to generate hydrogen atoms, and further generate hydrogen molecules. Hydroxyl ions pass through the porous diaphragm under the action of the electric field force between the cathode and anode, and reach the anode, where they lose electrons to generate water molecules and oxygen molecules.

[0003] According to Faraday's law, the amount of hydrogen produced by alkaline electrolysis of water is proportional to the current. Therefore, in order to increase the current, KOH solution is usually used as an electrolyte to increase the ion concentration. The KOH concentration in the solution has a great influence on increasing the electrolysis current. A large number of studies have shown that the concentration of KOH solution and the conductivity of the solution show a trend of first increasing and then decreasing. The conductivity of the KOH solution with a mass concentration of 30% is the highest. If the KOH concentration is further increased, the conductivity will decrease, which is not conducive to hydrogen production by electrolysis.

[0004] At present, the KOH solution with a mass concentration of 30% is commonly used in the field of alkaline water electrolysis hydrogen production. The power consumption caused by the solution resistance accounts for more than 20% of the total power consumption of the electrolyzer. This part of the power consumption increases the temperature of the electrolyzer alkali solution in the form of Joule heat. In the application of alkaline water electrolysis hydrogen production engineering, the heat of the alkali solution is useless. It is very necessary to find ways to reduce the solution resistance and reduce the Joule heat of the solution for alkaline water electrolysis hydrogen production technology. Summary of the invention

[0005] The purpose of the present invention is to provide an alkali solution for producing hydrogen by alkaline water electrolysis, a preparation method thereof, an alkaline water electrolysis hydrogen production system and an application thereof. The alkali solution in the present invention can improve the conductivity of the solution, reduce the resistance of the solution, reduce the Joule heat generated by the resistance of the solution, reduce the energy consumption of hydrogen production in the alkaline water electrolyzer, and at the same time reduce the operating temperature of the electrolyzer, saving power consumption.

[0006] The present invention provides an alkaline solution for producing hydrogen by alkaline water electrolysis, comprising potassium hydroxide, sodium hydroxide and deionized water;

[0007] The mass fraction of potassium hydroxide in the alkali solution is 20-40%, and the mass fraction of sodium hydroxide is 1-40%.

[0008] Preferably, the mass fraction of the potassium hydroxide is 25-35%.

[0009] Preferably, the mass fraction of potassium hydroxide is 30%.

[0010] Preferably, the mass fraction of the sodium hydroxide is 5 to 35%.

[0011] Preferably, the mass fraction of the sodium hydroxide is 5 to 20%.

[0012] The present invention provides a method for preparing an alkaline solution for producing hydrogen by alkaline water electrolysis as described above, comprising the following steps:

[0013] A) mixing potassium hydroxide with deionized water, and stirring to obtain a potassium hydroxide solution;

[0014] B) Add sodium hydroxide to potassium hydroxide solution, stir and dissolve, and obtain alkaline solution for producing hydrogen by alkaline water electrolysis.

[0015] Preferably, the stirring time in step A) is 0.5 to 2 hours, and the temperature of the potassium hydroxide solution is 25 to 45°C.

[0016] Preferably, the stirring time in step B) is 1 to 5 hours, and the temperature of the alkali solution is 25 to 50°C.

[0017] The present invention provides an alkaline water electrolysis hydrogen production system, comprising the alkaline solution for alkaline water electrolysis hydrogen production according to claim 1.

[0018] The present invention provides the use of the alkali solution for producing hydrogen by alkaline water electrolysis as described above in improving the resistivity of the alkali solution.

[0019] The present invention provides an alkali solution for producing hydrogen by alkaline water electrolysis, comprising potassium hydroxide, sodium hydroxide and deionized water; the mass fraction of potassium hydroxide in the alkali solution is 20-40%, and the mass fraction of sodium hydroxide is 1-40%. Under the condition that the concentration of KOH is not changed, the present invention adds sodium hydroxide to the alkali solution to increase the ion concentration in the solution, improve the conductivity of the solution, and reduce the resistance of the solution, thereby reducing the working temperature of hydrogen production by electrolysis and reducing the energy consumption of hydrogen production.

[0020] Compared with the prior art, the alkaline solution for producing hydrogen by alkaline water electrolysis and the preparation method of the present invention have the following advantages:

[0021] 1) Improve solution conductivity, reduce solution resistance, and lower the operating temperature of the alkaline water hydrogen production electrolyzer;

[0022] 2) Reduce the energy consumption of hydrogen production in alkaline water hydrogen production electrolyzer;

[0023] 3) The preparation method is simple, safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0025] Figure 1 It is the conductivity of the alkali solution with different NaOH contents in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The present invention provides an alkaline solution for producing hydrogen by alkaline water electrolysis, comprising potassium hydroxide, sodium hydroxide and deionized water;

[0027] The mass fraction of potassium hydroxide in the alkali solution is 20-40%, and the mass fraction of sodium hydroxide is 1-40%.

[0028] In the present invention, the potassium hydroxide is solid potassium hydroxide powder or flaky potassium hydroxide, and the purity is preferably greater than 90%. The mass fraction of the potassium hydroxide is preferably 20-40%, and more preferably 25-35%, such as 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0029] The sodium hydroxide is an alkaline additive in the form of solid powder or flakes, with a purity preferably greater than 95%, and a mass fraction preferably of 1-40%, more preferably 5-35%, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0030] In the present invention, the conductivity of the deionized water is preferably ≤1 μs / cm.

[0031] The present invention also provides a method for preparing the alkali solution for producing hydrogen by alkaline water electrolysis as described above, comprising the following steps:

[0032] A) mixing potassium hydroxide with deionized water, and stirring to obtain a potassium hydroxide solution;

[0033] B) Add sodium hydroxide to potassium hydroxide solution, stir and dissolve, and obtain alkaline solution for producing hydrogen by alkaline water electrolysis.

[0034] The present invention preferably adds potassium hydroxide solid into deionized water and stirs to obtain a potassium hydroxide solution, and then adds sodium hydroxide into the potassium hydroxide solution and stirs to obtain an alkali solution for producing hydrogen by alkaline water electrolysis.

[0035] In the present invention, the dosage of the potassium hydroxide and the sodium hydroxide is consistent with the dosage of the potassium hydroxide and the sodium hydroxide described above, and the present invention will not be repeated here.

[0036] In the present invention, the stirring time after adding the potassium hydroxide is preferably 0.5 to 2 hours, more preferably 1 to 1.5 hours, and the temperature is preferably 25 to 45° C., more preferably 30 to 45° C.; the stirring time after adding the sodium hydroxide is preferably 1 to 5 hours, more preferably 2 to 4 hours, and the temperature is 25 to 50° C., more preferably 30 to 50° C.

[0037] The present invention also provides an alkaline water electrolysis hydrogen production system, comprising the alkaline solution for alkaline water electrolysis hydrogen production as described above.

[0038] The alkali solution in the present invention is applicable to the currently common alkaline electrolysis hydrogen production system. Therefore, the present invention does not specifically limit the components in the alkaline electrolysis hydrogen production system, and the alkaline electrolysis hydrogen production system commonly used by those skilled in the art can be used.

[0039] The present invention also provides an application of the above-mentioned alkali solution for producing hydrogen by alkaline water electrolysis in improving the resistivity of the alkali solution. The alkali solution in the present invention can improve the solution conductivity, reduce the solution resistance, reduce the working temperature of hydrogen production by electrolysis, and reduce the energy consumption of hydrogen production.

[0040] The present invention provides an alkali solution for producing hydrogen by alkaline water electrolysis, comprising potassium hydroxide, sodium hydroxide and deionized water; the mass fraction of potassium hydroxide in the alkali solution is 20-40%, and the mass fraction of sodium hydroxide is 1-40%. Under the condition that the concentration of KOH is not changed, the present invention adds sodium hydroxide to the alkali solution to increase the ion concentration in the solution, improve the conductivity of the solution, and reduce the resistance of the solution, thereby reducing the working temperature of hydrogen production by electrolysis and reducing the energy consumption of hydrogen production.

[0041] Compared with the prior art, the alkaline solution for producing hydrogen by alkaline water electrolysis and the preparation method of the present invention have the following advantages:

[0042] 1) Improve solution conductivity, reduce solution resistance, and lower the operating temperature of the alkaline water hydrogen production electrolyzer;

[0043] 2) Reduce the energy consumption of hydrogen production in alkaline water hydrogen production electrolyzer;

[0044] 3) The preparation method is simple, safe and reliable.

[0045] In order to further illustrate the present invention, an alkali solution for producing hydrogen by alkaline water electrolysis, an alkaline water electrolysis hydrogen production system and applications provided by the present invention are described in detail below in conjunction with embodiments, but it should not be understood as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] First select volume>1.5m 3 The mixing container is removed and cleaned;

[0048] Step 1: Weigh 1000 kg of deionized water, the conductivity of which is ≤1 us / cm, and place it in a stirring container;

[0049] Step 2: Weigh 300 kg of KOH solid, KOH purity> 95%, slowly add it into a stirring container, and stir it for ≥ 0.5 h, and cool it naturally at a cooling temperature of ≤ 45°C.

[0050] Step 3: Slowly add the KOH solid in container b into container a and stir;

[0051] Step 4: Weigh a certain mass of alkaline additive C kg and place it in container c;

[0052] Step 5: Slowly add the alkaline additive in container c into container a and stir.

[0053] The resistivity of the alkali solution was tested, and the results are shown in Table 1 and Figure 1 shown.

[0054] Table 1 Resistivity of alkali solution with different NaOH contents

[0055]

[0056] As can be seen from Table 1, the addition of the alkaline additive NaOH to the KOH solution in the present invention can significantly reduce the conductivity of the alkali solution, wherein the combination of 30% KOH solution + 10% NaOH has the lowest conductivity.

[0057] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An alkaline water electrolysis hydrogen production system, characterized in that: The invention comprises an alkali solution for producing hydrogen by alkaline water electrolysis, wherein the alkali solution for producing hydrogen by alkaline water electrolysis comprises potassium hydroxide, sodium hydroxide and deionized water; The mass fraction of potassium hydroxide in the alkali solution is 25-35%, and the mass fraction of sodium hydroxide is 5-35%.

2. The alkaline water electrolysis hydrogen production system according to claim 1, characterized in that: The mass fraction of the potassium hydroxide is 30%.

3. The alkaline water electrolysis hydrogen production system according to claim 1, characterized in that: The mass fraction of the sodium hydroxide is 5-20%.

4. The alkaline water electrolysis hydrogen production system according to claim 1, characterized in that: The preparation method of the alkali solution comprises the following steps: A) mixing potassium hydroxide and deionized water, and stirring to obtain a potassium hydroxide solution; B) Add sodium hydroxide to potassium hydroxide solution, stir and dissolve to obtain alkaline solution for hydrogen production by alkaline water electrolysis.

5. The alkaline water electrolysis hydrogen production system according to claim 4, characterized in that: The stirring time in step A) is 0.5-2 hours, and the temperature of the potassium hydroxide solution is 25-45°C.

6. The alkaline water electrolysis hydrogen production system according to claim 4, characterized in that: The stirring time in step B) is 1 to 5 hours, and the temperature of the alkali solution is 25 to 50°C.

7. Use of the alkali solution in the alkaline water electrolysis hydrogen production system as claimed in claim 1 in reducing the resistivity of the alkali solution.

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