Electrolyte composite additive and application thereof in electrolyzed water (seawater)

Abstract

The invention discloses an electrolyte composite additive and application thereof in electrolyzed water (seawater), and belongs to the technical field of hydrogen production by electrolyzed water (seawater). The electrolyte composite additive is a combination of one of oxysalts and sodium benzoate; the concentration of oxysalt in the composite additive in the electrolyte is 5-50 mmol / L, and the concentration of sodium benzoate in the electrolyte is 0.1-5.0 mmol / L; when the composite additive is used in an electrolyte of a water (seawater) electrolysis hydrogen production technology, the corrosion resistance and the stability of a water (seawater) electrolysis catalyst can be improved, and the loss and the inactivation of active sites of the catalyst are effectively inhibited. The composite catalyst has universality for nickel-based catalysts in the field of hydrogen production by electrolyzing water (seawater). The method has great significance in cost reduction and efficiency improvement of a water (seawater) electrolysis hydrogen production technology, and has wide popularization and application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by electrolyzing water (seawater), and specifically designs an electrolyte composite additive and its application in electrolyzing water (seawater). Background Art

[0002] The proposal of the "dual carbon" goal has promoted clean energy to become a highly certain, long-term, and extensive industrial opportunity. As a sustainable and pollution-free energy cycle system, hydrogen energy has become one of the options for large-scale energy storage, bringing new opportunities to green chemistry. At present, China has laid out the development and application of hydrogen energy as one of the national energy strategic development directions, and leading enterprises in the energy field have been increasing their support for hydrogen energy. Green hydrogen with zero carbon emissions obtained by combining renewable energy and electrolytic hydrogen production is expected to become an effective way for large-scale hydrogen production in the future.

[0003] In the existing hydrogen production technology by electrolyzing water (seawater), the stability and corrosion resistance of the catalyst have always been the key issues restricting its large-scale development. OH - ions in the electrolyte will continuously attack the active sites of the catalyst, causing the dissolution of the active sites and the collapse of the catalyst structure, affecting the catalytic stability. Moreover, there are a large number of corrosive ions in the electrolyte of the electrolyzed seawater system, such as Cl - , Br - , etc. The corrosive ions will coordinate with the catalytic active sites, corrode the catalyst, and affect the catalytic stability. In order to improve the catalytic stability, existing technologies mostly focus on the catalyst structure design, but the regulation of the electrolyte components is still lacking. Therefore, this patent proposes a composite additive applied to the electrolyzed water (seawater) electrolyte, which can effectively improve the corrosion resistance and stability of the catalyst and is easy to operate. Summary of the Invention

[0004] The purpose of the present invention is to solve the key problems of poor corrosion resistance and stability in the existing technology of electrolyzing water (seawater), and provides an electrolyte composite additive applicable to electrolyzing water (seawater), belonging to the field of hydrogen production by electrolyzing water (seawater); the electrolyte composite additive is a combination of an oxygen-containing salt and sodium benzoate; the concentration of the oxygen-containing salt in the composite additive is 10 - 40 mmol / L; the concentration of sodium benzoate is 0.5 - 4.5 mmol / L; when using the composite additive of the present invention in electrolyzing water (seawater), it can improve the corrosion resistance and stability of the electrolyzed water (seawater) catalyst, and effectively inhibit the dissolution of the catalytic active sites and the damage of the catalyst structure. The electrolyte composite additive of the present invention is of great significance for the development of electrolyzing water (seawater) and has broad prospects for popularization and application.

[0005] To achieve the above technical effects, the following technical solutions are adopted;

[0006] An electrolyte composite additive, and the composite additive is a combination of an oxygen-containing salt and sodium benzoate.

[0007] Further, the oxygen-containing salt is one or more of phosphate, sulfate, carbonate, tungstate, molybdate, selenate, borate.

[0008] Further, the concentration of the oxygen-containing salt in the electrolyte is 15 - 35 mmol / L; the concentration of sodium benzoate in the electrolyte is 0.3 - 4.0 mmol / L.

[0009] An application of an electrolyte composite additive in electrolyzed water (seawater), comprising the following steps:

[0010] Step 1: Prepare an electrolyzed water (seawater) electrolyte, including potassium hydroxide or sodium hydroxide, sodium chloride, seawater and water;

[0011] Step 2: Dissolve sodium benzoate as additive 1 in the electrolyzed water (seawater) electrolyte obtained in Step 1 to obtain an electrolyzed water (seawater) electrolyte containing sodium benzoate;

[0012] Step 3: Dissolve the oxygen-containing salt as additive 2 in the electrolyzed water (seawater) electrolyte containing sodium benzoate obtained in Step 2;

[0013] The electrolyzed water (seawater) electrolyte is divided into three types. One is an alkaline electrolyzed water hydrogen production electrolyte, which is an aqueous solution of potassium hydroxide or sodium hydroxide, and the concentration of potassium hydroxide or sodium hydroxide therein is 0.1 - 7 mol / L; the second is a simulated seawater electrolyte, which is a mixed aqueous solution of potassium hydroxide or sodium hydroxide and sodium chloride, and the concentration of potassium hydroxide or sodium hydroxide therein is 0.1 - 7 mol / L, and the concentration of sodium chloride is 0.3 - 2.3 mol / L; the third is a real seawater electrolyte, which is an electrolyte obtained by dissolving potassium hydroxide or sodium hydroxide in seawater and filtering, and the concentration of potassium hydroxide or sodium hydroxide therein is 0.1 - 7 mol / L.

[0014] Further, the composite additive is a combination of an oxygen-containing salt and sodium benzoate;

[0015] Further, the oxygen-containing salt is one or more of phosphate, sulfate, carbonate, tungstate, molybdate, selenate, borate;

[0016] Further, the concentration of the oxygen-containing salt in the electrolyte is 13 - 30 mmol / L; the concentration of sodium benzoate in the electrolyte is 0.5 - 3.5 mmol / L.

[0017] Further, the electrolyzed water (seawater) electrolyte composite additive is applicable to all nickel-based catalysts in the field of electrolyzed water (seawater) technology.

[0018] Further, the concentration of the oxygen-containing salt in the electrolyte solution is 15 - 25 mmol / L.

[0019] Further, the concentration of sodium benzoate in the electrolyte is 0.8 - 3.0 mmol / L.

[0020] Further, the concentration of potassium hydroxide or sodium hydroxide in the electrolyzed water (seawater) electrolyte is 0.5 - 6 mol / L.

[0021] Further, the concentration of sodium chloride in the electrolyzed water (seawater) electrolyte is 0.5 - 2 mol / L.

[0022] Further, the electrolyzed water (seawater) electrolyte includes an anode electrolyte and a cathode electrolyte.

[0023] Further, the electrolyzed water (seawater) electrolyte composite additive is applicable to all nickel-based catalysts in the field of electrolyzed water (seawater) technology.

[0024] In the present invention, by adding sodium benzoate and introducing benzoate ions, during the electrolysis process, the benzoate ions are adsorbed onto the catalyst surface and combined with the active sites of the catalyst. Through the steric hindrance effect, the stability of the active sites is enhanced, thereby inhibiting the inactivation of the catalyst and enhancing the electrolysis stability. Since the carboxylate functional group in the benzoate ion has hydrophilic properties, the hydrophilicity of the catalyst is improved. A higher hydrophilicity during the electrolysis process is beneficial to the electrolysis process. The adsorption of benzoate ions also increases the number of hydrogen bonds formed between the surface sites of the catalyst and water, accelerating the electrolysis kinetic process.

[0025] In the present invention, by introducing one or several oxygen-containing salts, through the introduced oxygen-containing anions, using the electrostatic repulsion effect, the diffusion resistance of corrosion ions (Cl - and Br - ) in the electrolyte solution towards the catalyst surface is increased, the corrosion of the catalyst by the corrosion ions is inhibited, and the stability and corrosion resistance of the catalyst are improved.

[0026] The preparation method of the electrolyte of the composite additive for electrolyzed water (seawater) in the present invention has a simple process, is easy to operate, and has a low cost. At the same time, it can enhance the stability and corrosion resistance of the catalyst in electrolyzed water (seawater) and extend the electrolysis life. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. The drawings described below are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0028] Figure 1 The constant voltage stability test curve in Comparative Example 1 of the present invention;

[0029] Figure 2 The constant voltage stability test curve in Example 1 of the present invention;

[0030] Figure 3 The constant voltage stability test curve in Example 2 of the present invention;

[0031] Figure 4 The constant voltage stability test curve in Example 3 of the present invention;

[0032] Figure 5 The constant voltage stability test curve in Example 4 of the present invention;

[0033] Figure 6 The constant voltage stability test curve in Example 5 of the present invention;

[0034] Figure 7 The constant current stability test curve in Example 6 of the present invention;

[0035] Figure 8 The constant current stability test curve in Example 7 of the present invention;

[0036] Figure 9 The constant current stability test curve in Example 8 of the present invention. Detailed implementation manners

[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0038] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanations for the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0039] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary implementation manners according to the present invention. As used herein, unless otherwise clearly specified in the context, the singular form includes the plural form. In addition, it should also be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations and / or combinations thereof.

[0040] Comparative Example 1:

[0041] This comparative example is used for comparison with the examples. A mixed solution of potassium hydroxide and sodium chloride is prepared as the electrolyte, where the concentration of potassium hydroxide is 1 mol / L and the concentration of sodium chloride is 0.5 mol / L. The electrolytic anode catalyst is nickel-iron hydrotalcite, and the cathode catalyst is Raney nickel. A two-electrode test system is adopted to conduct a constant voltage test in the prepared electrolyte, and the voltage is set to 4.0 V. Under the above test conditions, the Figure 1 obtained constant voltage stability test curve. It can be seen from the experimental results that after the catalyst undergoes a 100-hour constant voltage stability test, the current density decays from the initial 1.3 A / cm 2 to 0.9 A / cm 2 , indicating that its catalytic activity decays, showing poor corrosion resistance and stability.

[0042] Example 1:

[0043] A mixed solution of potassium hydroxide and sodium chloride is prepared as the electrolyte, where the concentration of potassium hydroxide is 1 mol / L and the concentration of sodium chloride is 0.5 mol / L. Sodium tungstate and sodium benzoate, as composite additives, are added to the electrolyte, where the concentration of sodium tungstate is 15 mmol / L and the concentration of sodium benzoate is 2 mmol / L. The electrolytic anode catalyst is nickel-iron hydrotalcite, and the cathode catalyst is Raney nickel. A two-electrode test system is adopted to conduct a constant voltage test in the prepared electrolyte, and the voltage is set to 4.0 V. Under the above test conditions, the Figure 2 obtained constant voltage stability test curve. It can be seen from the experimental results that in the electrolyte containing the composite additive, after the catalyst undergoes a 100-hour constant voltage stability test, the current density still remains at the initial 1.3 A / cm 2 . Compared with the experimental results of Comparative Example 1, it is proved that the addition of the composite additive improves the corrosion resistance and stability of the catalyst.

[0044] Example 2:

[0045] A mixed solution of potassium hydroxide and sodium chloride is prepared as the electrolyte, where the concentration of potassium hydroxide is 1 mol / L and the concentration of sodium chloride is 0.5 mol / L. Sodium phosphate and sodium benzoate, as composite additives, are added to the electrolyte, where the concentration of sodium phosphate is 15 mmol / L and the concentration of sodium benzoate is 2 mmol / L. The electrolytic anode catalyst is nickel-iron hydrotalcite, and the cathode catalyst is Raney nickel. A two-electrode test system is adopted to conduct a constant voltage test in the prepared electrolyte, and the voltage is set to 4.0 V. Under the above test conditions, the Figure 3 obtained constant voltage stability test curve. It can be seen from the experimental results that in the electrolyte containing the composite additive, after the catalyst undergoes a 100-hour constant voltage stability test, the current density still remains at the initial 1.3 A / cm 2The current density, compared with the experimental results of Comparative Example 1, proves that the addition of the composite additive improves the corrosion resistance and stability of the catalyst.

[0046] Example 3:

[0047] Prepare a mixed solution of potassium hydroxide and sodium chloride as the electrolyte, where the concentration of potassium hydroxide is 1 mol / L and the concentration of sodium chloride is 0.5 mol / L. Add the composite additives sodium carbonate and sodium benzoate to the electrolyte, where the concentration of sodium carbonate is 15 mmol / L and the concentration of sodium benzoate is 2 mmol / L. The electrolytic anode catalyst is nickel-iron hydrotalcite, and the cathode catalyst is Raney nickel. Use a two-electrode test system to conduct a constant voltage test in the prepared electrolyte, and the voltage is set to 4.0 V. Under the above test conditions, obtain Figure 4 The constant voltage stability test curve. It can be seen from the experimental results that when the catalyst is in the electrolyte containing the composite additive, after 100 hours of constant voltage stability test, the current density still remains at the initial 1.3 A / cm 2 The current density, compared with the experimental results of Comparative Example 1, proves that the addition of the composite additive improves the corrosion resistance and stability of the catalyst.

[0048] Example 4:

[0049] Prepare a mixed solution of potassium hydroxide and sodium chloride as the electrolyte, where the concentration of potassium hydroxide is 1 mol / L and the concentration of sodium chloride is 0.5 mol / L. Add the composite additives sodium sulfate and sodium benzoate to the electrolyte, where the concentration of sodium sulfate is 15 mmol / L and the concentration of sodium benzoate is 2 mmol / L. The electrolytic anode catalyst is nickel-iron hydrotalcite, and the cathode catalyst is Raney nickel. Use a two-electrode test system to conduct a constant voltage test in the prepared electrolyte, and the voltage is set to 4.0 V. Under the above test conditions, obtain Figure 5 The constant voltage stability test curve. It can be seen from the experimental results that when the catalyst is in the electrolyte containing the composite additive, after 100 hours of constant voltage stability test, the current density still remains at the initial 1.3 A / cm 2 The current density, compared with the experimental results of Comparative Example 1, proves that the addition of the composite additive improves the corrosion resistance and stability of the catalyst.

[0050] Example 5:

[0051] Prepare a mixed solution of potassium hydroxide and sodium chloride as the electrolyte, where the concentration of potassium hydroxide is 1 mol / L and the concentration of sodium chloride is 0.5 mol / L. Add the composite additives sodium molybdate and sodium benzoate to the electrolyte, where the concentration of sodium molybdate is 15 mmol / L and the concentration of sodium benzoate is 2 mmol / L. The electrolytic anode catalyst is nickel-iron hydrotalcite, and the cathode catalyst is Raney nickel. Use a two-electrode test system to conduct a constant voltage test in the prepared electrolyte, and set the voltage to 4.0 V. Under the above test conditions, obtain Figure 6 the constant voltage stability test curve. It can be seen from the experimental results that after 100 hours of constant voltage stability test in the electrolyte containing the composite additive, the current density of the catalyst still remains at the initial 1.3 A / cm 2 of the current density. Comparing with the experimental results of Comparative Example 1, it is proved that the addition of the composite additive improves the corrosion resistance and stability of the catalyst.

[0052] Example 6:

[0053] Prepare a mixed solution of potassium hydroxide and sodium chloride as the electrolyte, where the concentration of potassium hydroxide is 1 mol / L and the concentration of sodium chloride is 0.5 mol / L. Add the composite additives sodium tungstate and sodium benzoate to the electrolyte, where the concentration of sodium tungstate is 15 mmol / L and the concentration of sodium benzoate is 2 mmol / L. The electrolytic anode catalyst is nickel foam, and the cathode catalyst is Raney nickel. Use a two-electrode test system to conduct a constant current test in the prepared electrolyte, and set the current to 1.2 A / cm 2 . Under the above test conditions, obtain Figure 7 the constant current stability test curve. It can be seen from the experimental results that after 150 hours of constant voltage stability test in the electrolyte containing the composite additive, the voltage basically remains unchanged. However, in the case without the additive, the electrolytic voltage rises rapidly and the catalyst is deactivated. Comparing the experimental results, it is proved that the addition of the composite additive improves the corrosion resistance and stability of the catalyst.

[0054] Example 7:

[0055] Prepare a mixed solution of potassium hydroxide and sodium chloride as the electrolyte, where the concentration of potassium hydroxide is 1 mol / L and the concentration of sodium chloride is 0.5 mol / L. Add the composite additives sodium tungstate and sodium benzoate to the electrolyte, where the concentration of sodium tungstate is 15 mmol / L and the concentration of sodium benzoate is 2 mmol / L. The electrolytic anode catalyst is nickel hydroxide, and the cathode catalyst is Raney nickel. Use a two-electrode test system to conduct a constant current test in the prepared electrolyte, and set the current to 1.2 A / cm 2 . Under the above test conditions, obtain Figure 8The constant current stability test curve. It can be seen from the experimental results that after 150 hours of constant voltage stability test, the voltage of the catalyst in the electrolyte containing the composite additive remains basically unchanged. However, in the case without the additive, the electrolysis voltage rises rapidly and the catalyst is deactivated. The comparison of the experimental results proves that the addition of the composite additive improves the corrosion resistance and stability of the catalyst.

[0056] Example 8:

[0057] Prepare a mixed solution of potassium hydroxide and sodium chloride as the electrolyte, where the concentration of potassium hydroxide is 1 mol / L and the concentration of sodium chloride is 0.5 mol / L. Add the composite additives sodium tungstate and sodium benzoate to the electrolyte, where the concentration of sodium tungstate is 15 mmol / L and the concentration of sodium benzoate is 2 mmol / L. The electrolytic anode catalyst is nickel oxide and the cathode catalyst is Raney nickel. A two-electrode test system is used to conduct a constant current test in the prepared electrolyte, and the current is set to 1.2 A / cm 2 . Under the above test conditions, the Figure 9 constant current stability test curve is obtained. It can be seen from the experimental results that after 120 hours of constant voltage stability test, the voltage of the catalyst in the electrolyte containing the composite additive remains basically unchanged. However, in the case without the additive, the electrolysis voltage rises rapidly and the catalyst is deactivated. The comparison of the experimental results proves that the addition of the composite additive improves the corrosion resistance and stability of the catalyst.

Claims

1. An application of an electrolyte composite additive in the field of hydrogen production by electrolysis of water (seawater), characterized in that: The application comprises the following steps: Step 1: preparing an electrolyzed water (seawater) electrolyte, including potassium hydroxide or sodium hydroxide, sodium chloride, seawater and water; Step 2: dissolving sodium benzoate as an additive 1 in the electrolyzed water (seawater) electrolyte obtained in step 1 to obtain an electrolyzed water (seawater) electrolyte containing sodium benzoate; Step 3: dissolving the oxygen-containing salt as additive 2 in the electrolyzed water (seawater) electrolyte containing sodium benzoate obtained in step 2; The electrolyzed water (seawater) electrolyte is divided into three types, one is an alkaline electrolyzed water hydrogen production electrolyte, which is an aqueous solution of potassium hydroxide or sodium hydroxide, wherein the concentration of potassium hydroxide or sodium hydroxide is 0.05-8 mol / L; the second is a simulated seawater electrolyte, which is a mixed aqueous solution of potassium hydroxide or sodium hydroxide and sodium chloride, wherein the concentration of potassium hydroxide or sodium hydroxide is 0.05-8 mol / L, and the concentration of sodium chloride is 0.1-2.5 mol / L; the third is a real seawater electrolyte, which is an electrolyte obtained by dissolving potassium hydroxide or sodium hydroxide in seawater and filtering, wherein the concentration of potassium hydroxide or sodium hydroxide is 0.05-8 mol / L; The composite additive is a combination of an oxyacid salt and sodium benzoate; The oxygen-containing salt is one or more of phosphate, sulfate, carbonate, tungstate, borate, selenate, and molybdate; The concentration of the oxygen-containing acid salt in the electrolyte is 5-50 mmol / L; the concentration of the sodium benzoate in the electrolyte is 0.1-5.0 mmol / L.

2. The use as claimed in claim 1, characterized in that The concentration of the oxygen-containing acid salt in the electrolyte is 10-40 mmol / L.

3. The use as claimed in claim 1, characterized in that The concentration of the sodium benzoate in the electrolyte is 0.5-4.5 mmol / L.

4. The use as claimed in claim 1, characterized in that The concentration of potassium hydroxide or sodium hydroxide in the electrolyzed water (seawater) electrolyte is 0.1-7 mol / L.

5. The use as claimed in claim 1, characterized in that The concentration of sodium chloride in the electrolyzed water (seawater) electrolyte is 0.5-2 mol / L.

6. The use as claimed in claim 1, characterized in that The electrolyzed water (seawater) electrolyte comprises an anode electrolyte and a cathode electrolyte.

7. The use as claimed in claim 1, characterized in that The electrolytic water (seawater) electrolyte composite additive is applicable to all nickel-based catalysts in the technical field of electrolytic water (seawater).

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