Application and method of phytic acid compound in inhibition of anode chlorine evolution reaction through seawater electrolysis

Abstract

The invention discloses application and a method of phytic acid compounds in inhibition of anode chlorine evolution reaction through seawater electrolysis. The phytic acid compound can be applied to electrolyte for seawater electrolysis to inhibit anode chlorine evolution reaction, the electrolyte is an aqueous solution containing chloride ions, and the electrolyte further comprises the phytic acid compound. The method comprises the following steps: electrifying an electrochemical reaction system comprising a cathode, an anode and an electrolyte for electrolysis so as to obtain hydrogen at the cathode and oxygen at the anode; the electrolyte is an aqueous solution containing chloride ions, and the electrolyte further comprises a phytic acid compound. When the phytic acid compound is used for seawater electrolysis, adsorption and oxidation of chloride ions on an anode can be remarkably improved, the chlorine evolution reaction of the anode can be effectively inhibited, the anode is protected from being corroded, and the seawater electrolysis efficiency is improved; and the phytic acid compound is derived from biomass, is low in price and is easy to popularize and apply.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen production by seawater electrolysis, and specifically relates to an application and method of phytic acid compounds in inhibiting anode chlorine evolution reaction by seawater electrolysis. Background Art

[0002] Green transformation of energy is an important way to achieve sustainable development. Hydrogen, as an ideal carbon-free energy, is an important carrier for realizing large-scale storage of green energy. Vigorously developing the hydrogen energy industry will help realize the country's "dual carbon strategy". In recent years, the use of renewable resources such as wind and solar energy to electrolyze water to produce hydrogen has been a hot topic in the energy industry. Traditional energy companies and new start-ups have laid out materials and equipment products related to electrolysis of water to produce hydrogen. At present, the raw materials used in mature electrolysis water technologies such as ALK, PEM, AEM and other electrolyzers are all purified fresh water, but fresh water resources are unevenly distributed and scarce. Fresh water only accounts for 2.53% of the world's total water. Most of the water resources exist in seawater. Therefore, using seawater as a raw material for electrolysis of water is an effective way to increase hydrogen energy to large-scale energy storage. However, the oxidation reaction of high-concentration chloride ions in seawater at the anode competes with the oxygen evolution reaction. The same hydrogen production efficiency requires a higher voltage and increased energy consumption; secondly, the oxidation of chloride ions in seawater at the anode produces chlorine and hypochlorite, which form a strong oxidizing environment, which will cause corrosion of the anode and other parts of the electrolyzer. Therefore, in order to realize the industrialization of hydrogen production by seawater electrolysis, the adsorption and oxidation of chloride ions at the anode must be overcome. There are two main ways to solve this problem: one is to use specially optimized anode catalysts, but this method is costly and the catalyst stability is poor; the other is to directly add additives to the electrolyte to inhibit the adsorption and oxidation of chloride ions. However, there is no research on adding biomass compounds to inhibit the adsorption and oxidation of chloride ions. Summary of the invention

[0003] The main purpose of the present invention is to provide an application and method of phytic acid compounds in inhibiting anode chlorine evolution reaction in seawater electrolysis, so as to overcome the shortcomings of the prior art.

[0004] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes: One aspect of the present invention provides the use of phytic acid compounds in inhibiting anode chlorine evolution reaction in seawater electrolysis.

[0005] Furthermore, the phytic acid compound includes at least any one of phytic acid, dodecasodium phytate, dipotassium phytate, etc. Another aspect of the present invention provides an electrolyte for suppressing anodic chlorine evolution reaction in seawater electrolysis. The electrolyte is an aqueous solution containing chloride ions, and the electrolyte also includes a phytic acid compound.

[0006] Another aspect of the present invention provides a method for inhibiting anode chlorine evolution reaction by seawater electrolysis, the method comprising: The electrochemical reaction system including a cathode, an anode and an electrolyte is energized for electrolysis, thereby obtaining hydrogen at the cathode and oxygen at the anode; the electrolyte is an aqueous solution containing chloride ions, and the electrolyte also includes phytic acid compounds.

[0007] Compared with the prior art, the present invention has at least the following beneficial effects: (1) In the method of suppressing chlorine evolution reaction at the anode by electrolysis of seawater of the present invention, during the electrolysis process, phytate ions are enriched on the anode surface, which suppress the adsorption of chloride ions by electrostatic repulsion. The hypophosphite ions can compete with chloride ions for adsorption sites, suppressing the oxidation reaction of chloride ions, thereby greatly reducing the negative impact of chloride ions on electrolyzed water.

[0008] (2) Phytic acid compounds are derived from biomass and are inexpensive. They can significantly improve the adsorption and oxidation of chloride ions at the anode, effectively protect the anode from corrosion, and improve the efficiency of seawater electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 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 some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0010] Figure 1 This is a schematic diagram of the effect of the phytic acid compounds of the present invention on the electrolysis process of seawater; Figure 2 The electrochemical reaction system of Example 1 of the present invention and Comparative Example 1 is 20 mA / cm 2 Constant current stability test diagram under current density; Figure 3 The electrochemical reaction system of Example 2 of the present invention and Comparative Example 2 is 20 mA / cm 2 Constant current stability test diagram under current density; Figure 4 The electrochemical reaction system of Example 3 of the present invention and Comparative Example 3 at 20 mA / cm 2 Constant current stability test diagram under current density. DETAILED DESCRIPTION

[0011] In view of the problems existing in the above-mentioned prior art, the inventors of the present invention have conducted extensive and in-depth research and provided an application and method of phytic acid compounds in inhibiting anode chlorine evolution reaction in seawater electrolysis. The application and method mainly include adding phytic acid compounds into the electrolyte to inhibit anode chlorine evolution reaction in the process of seawater electrolysis.

[0012] The technical solution, its implementation process and principle will be further explained as follows.

[0013] As one aspect of the technical solution of the present invention, it provides the use of phytic acid compounds in inhibiting anode chlorine evolution reaction in seawater electrolysis.

[0014] In some embodiments, the phytic acid compound includes at least any one of phytic acid, phytic acid dodecasodium salt, dipotassium phytate, etc., but is not limited thereto. Phosphate ions can compete with chloride ions for adsorption sites, inhibit the oxidation reaction of chloride ions, thereby reducing the concentration of chloride ions, greatly reducing the negative impact of chloride ions on electrolyzed water, and improving the efficiency of electrolyzed seawater.

[0015] As one aspect of the technical solution of the present invention, an electrolyte for suppressing anodic chlorine evolution reaction in seawater electrolysis is provided. The electrolyte is an aqueous solution containing chloride ions, and the electrolyte also includes a phytic acid compound.

[0016] In some embodiments, the phytic acid compound includes at least any one of phytic acid, dodecasodium phytate, dipotassium phytate, etc., but is not limited thereto.

[0017] In some embodiments, the concentration of the phytic acid compound in the electrolyte is 1 mmol / L to 200 mmol / L. When the concentration exceeds 200 mmol / L, the phytic acid compound is relatively stable in the electrolyte and can effectively react with chlorine at the anode, but the economic cost will be increased.

[0018] In some embodiments, the electrolyte includes an alkaline electrolyte or a neutral electrolyte.

[0019] In some embodiments, the alkaline electrolyte includes a mixed solution of an alkaline inorganic compound and a chloride salt.

[0020] In some preferred embodiments, the alkaline inorganic compound includes at least any one of potassium hydroxide or sodium hydroxide, but is not limited thereto.

[0021] In some preferred embodiments, the chloride salt includes at least any one of sodium chloride, potassium chloride, lithium chloride, etc., but is not limited thereto.

[0022] In some preferred embodiments, the pH value of the alkaline electrolyte is 8-14.

[0023] In some embodiments, the neutral electrolyte comprises an aqueous chloride brine solution.

[0024] In some preferred embodiments, the chloride salt includes at least any one of sodium chloride, potassium chloride, lithium chloride, etc., but is not limited thereto.

[0025] As another aspect of the technical solution of the present invention, a method for inhibiting chlorine evolution reaction at the anode by electrolysis of seawater is provided, the method comprising: The electrochemical reaction system including a cathode, an anode and an electrolyte is energized for electrolysis, thereby obtaining hydrogen at the cathode and oxygen at the anode; the electrolyte is an aqueous solution containing chloride ions, and the electrolyte also includes phytic acid compounds.

[0026] The specific mechanism of seawater electrolysis inhibiting chlorine evolution reaction at the anode is as follows: there are six phosphate groups on one molecule of phytic acid compounds. This ordered phosphate group can effectively repel chloride ions from approaching the anode electrode surface through electrostatic action, thereby inhibiting the occurrence of chlorine evolution reaction.

[0027] In some embodiments, the electrolysis time is 35 to 100 h.

[0028] In some embodiments, the electrolysis current is 10-500 mA / cm 2 , voltage is 1~3 V ( vs . RHE).

[0029] In some embodiments, the electrochemical reaction system includes a three-electrode system and an electrolyte, wherein the three-electrode system includes a cathode, an anode, and a reference electrode.

[0030] In some embodiments, the electrochemical reaction system includes a two-electrode system and an electrolyte, wherein the two-electrode system includes a cathode and an anode.

[0031] In some embodiments, the cathode includes a conductive substrate.

[0032] In some preferred embodiments, the conductive substrate is titanium felt obtained by depositing at least any one of nickel ions, iron ions, cobalt ions, and the like.

[0033] In some preferred embodiments, the material of the conductive substrate includes at least any one of foam copper, copper sheet, foam nickel, nickel sheet, foam cobalt, cobalt sheet, foam iron, iron sheet, steel plate, titanium mesh, etc., but is not limited thereto.

[0034] In some embodiments, the anode includes at least any one of a platinum sheet or a carbon rod, etc., but is not limited thereto.

[0035] In some embodiments, the reference electrode includes at least any one of a calomel electrode or a silver / silver chloride electrode, but is not limited thereto.

[0036] In some embodiments, the Faradaic efficiency of seawater electrolysis is above 80%.

[0037] In summary, the present invention can significantly improve the adsorption and oxidation of chloride ions at the anode by adding phytic acid compounds to the electrolyte, can effectively inhibit the chlorine evolution reaction at the anode, protect the anode from corrosion, and improve the efficiency of seawater electrolysis; and phytic acid compounds are derived from biomass, are low in price, and are easy to promote and apply.

[0038] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with Examples and Comparative Examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art will make modifications or equivalent substitutions based on the understanding of the technical scheme of the present invention, without departing from the spirit and scope of the technical scheme of the present invention, and all should be included in the protection scope of the present invention.

[0039] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they can be obtained commercially and do not involve the core technical means of the present invention.

[0040] Example 1 The three-electrode method was used, in which the reference electrode was a saturated calomel electrode and the counter electrode was a Pt sheet electrode. First, the Ti felt was used as the working electrode and placed in a solution with a concentration of 3 mmol / L for Co ions and Ni ions for deposition. The Ti felt after deposition was placed in a muffle furnace and sintered at 200-300°C for 2-3 hours. After sintering, the Ti felt was used as the working electrode, the anode was a platinum sheet electrode, the electrolyte was a sodium chloride aqueous solution, the concentration of sodium chloride was 0.5 mol / L, and the molar concentration of phytic acid dodecasodium salt was 1 mmol / L. The electrochemical system was tested at 20 mA / cm 2 Constant current stability under current density, test results are shown in Figure 2 , stable operation time exceeds 40h, and Faraday efficiency is 85%.

[0041] Example 2 The three-electrode method was used, in which the reference electrode was a saturated calomel electrode and the counter electrode was a Pt sheet electrode. First, the Ti felt was used as the working electrode and placed in a solution with a concentration of 3 mmol / L for Fe ions and Co ions for deposition. The Ti felt after deposition was placed in a muffle furnace and sintered at 200-300°C for 2-3 hours. After sintering, the Ti felt was used as the working electrode, the anode was a platinum sheet electrode, and the electrolyte was a sodium chloride aqueous solution, in which the concentration of sodium chloride was 0.5 mol / L, and the molar concentration of phytic acid dodecasodium salt was 1.5 mmol / L. The test was 20 mA / cm 2 Constant current stability under current density, test results are shown in Figure 3 , stable operation time exceeds 35h, and Faraday efficiency is 82%.

[0042] Example 3 The three-electrode method was used, in which the reference electrode was a saturated calomel electrode and the counter electrode was a Pt sheet electrode. First, the Ti felt was used as the working electrode and placed in a solution with a concentration of 3 mmol / L for Fe ions, Co ions, and Ni ions. The Ti felt after deposition was placed in a muffle furnace and sintered at 200-300°C for 2-3 hours. After sintering, the Ti felt was used as the working electrode, the anode was a platinum sheet electrode, and the electrolyte was a sodium chloride aqueous solution, in which the concentration of sodium chloride was 0.5 mol / L, and the molar concentration of dipotassium phytate was 2 mmol / L. The test was 20 mA / cm 2 Constant current stability under current density, test results are shown in Figure 4 , stable operation time exceeds 60h, and Faraday efficiency is 90%.

[0043] Example 4 The Ti felt loaded with iron, cobalt and nickel oxide in Example 3 was used as the working electrode, the anode was a platinum sheet electrode, the electrolyte was a sodium chloride aqueous solution, wherein the concentration of sodium chloride was 0.5 mol / L, the molar concentration of phytic acid was 2 mmol / L, the pH was adjusted to neutral, and the test was 20 mA / cm 2 The constant current stability under the current density is stable for 30 hours. The Faraday efficiency is 85%.

[0044] Example 5 The Ti felt loaded with iron, cobalt and nickel oxide in Example 3 was used as the working electrode, the anode was a platinum sheet electrode, the electrolyte was a sodium chloride aqueous solution, wherein the concentration of sodium chloride was 0.5 mol / L, the molar concentration of phytic acid dodecasodium salt was 200 mmol / L, and the test was 20 mA / cm 2 The constant current stability under the current density is stable for 30 hours. The Faraday efficiency is 88%.

[0045] Example 6 Ti felt was used as the working electrode, the anode was a platinum electrode, the electrolyte contained 0.5 mol / L sodium chloride, 1 mol / L potassium hydroxide, and 2 mmol / L phytic acid dodecasodium salt. Test 20 mA / cm 2 The constant current stability under the current density is stable for 30 hours. The Faraday efficiency is 92%.

[0046] Comparative Example 1 The difference from Example 1 is that the electrolyte is a sodium chloride aqueous solution with a concentration of 0.5 mol / L, and no dodecasodium phytate is added. Test 20 mA / cm 2 Constant current stability under current density, test results are shown in Figure 2 The performance decays quickly, mainly because the strong oxidizing hypochlorous acid is generated and dissolves the catalyst.

[0047] Comparative Example 2 The difference from Example 2 is that the electrolyte is a sodium chloride aqueous solution with a concentration of 0.5 mol / L, and no dodecasodium phytate is added. Test 20 mA / cm 2 Constant current stability under current density, test results are shown in Figure 3 It was found that the performance declined sharply after 15 hours, indicating that the performance declined quickly without adding phytic acid compounds.

[0048] Comparative Example 3 The difference from Example 3 is that the electrolyte is a sodium chloride aqueous solution with a concentration of 0.5 mol / L, and no dipotassium phytate is added. Figure 4 , tested at 20mA / cm 2 The constant current stability under current density showed that the performance decayed sharply after 15 h, indicating that the performance decayed quickly without adding phytic acid compounds.

[0049] Comparative Example 4 The difference from Example 4 is that the electrolyte is a sodium chloride aqueous solution with a concentration of 0.5 mol / L, and no phytic acid is added. Test 20 mA / cm 2 The constant current stability under current density shows that the performance decays very quickly, mainly because the strong oxidizing acid produced dissolves the catalyst.

[0050] Comparative Example 5 The difference from Example 6 is that the electrolyte is 0.5 mol / L sodium chloride and 1 mol / L potassium hydroxide, and no dodecasodium phytate is added. Test 20 mA / cm 2 The constant current stability under different current densities showed that the performance decayed sharply after 15 h.

[0051] Comparative Example 6 The difference from Example 3 is that the electrolyte is a sodium chloride aqueous solution with a concentration of 0.5 mol / L and 0.1 mmol / L of phytic acid dodecasodium salt. The Faraday efficiency is 70%.

[0052] Comparative Example 7 The difference from Example 3 is that the electrolyte is a sodium chloride aqueous solution with a concentration of 0.5 mol / L and 300 mmol / L of phytic acid dodecasodium salt. The Faraday efficiency is 85%.

[0053] The various aspects, embodiments, features and examples of the present invention should be considered as illustrative in all aspects and are not intended to limit the present invention, the scope of the present invention is defined only by the claims. Other embodiments, modifications and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.

[0054] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0055] Although the present invention has been described with reference to illustrative embodiments, it will be appreciated by those skilled in the art that various other changes, omissions and / or additions may be made and that elements of the described embodiments may be substituted with substantial equivalents without departing from the spirit and scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from the scope of the present invention. Therefore, it is not intended herein to limit the present invention to the disclosed specific embodiments for carrying out the present invention, but rather it is intended that the present invention will include all embodiments within the scope of the appended claims.

Claims

1. Application of phytic acid compounds in inhibiting anodic chlorine evolution reaction in seawater electrolysis.

2. The use according to claim 1, characterized in that: The phytic acid compound includes at least any one of phytic acid, dodecasodium phytate and dipotassium phytate.

3. An electrolyte for suppressing anodic chlorine evolution reaction in seawater electrolysis, characterized in that: The electrolyte is an aqueous solution containing chloride ions, and the electrolyte also includes phytic acid compounds.

4. The electrolyte according to claim 3, characterized in that: The phytic acid compound includes at least any one of phytic acid, dodecasodium phytate, and dipotassium phytate; And / or, the concentration of phytic acid compounds in the electrolyte is 1 mmol / L to 200 mmol / L; And / or, the electrolyte includes an alkaline electrolyte or a neutral electrolyte.

5. The electrolyte according to claim 4, characterized in that: The alkaline electrolyte includes a mixed solution of an alkaline inorganic compound and a chloride salt; Preferably, the alkaline inorganic compound includes at least one of potassium hydroxide or sodium hydroxide; Preferably, the chloride salt includes at least any one of sodium chloride, potassium chloride and lithium chloride; Preferably, the pH value of the alkaline electrolyte is 8-14; and / or, the neutral electrolyte comprises a chloride salt solution; Preferably, the chloride salt includes at least any one of sodium chloride, potassium chloride and lithium chloride.

6. A method for inhibiting anodic chlorine evolution reaction by seawater electrolysis, characterized in that: include: The electrochemical reaction system including a cathode, an anode and an electrolyte is energized for electrolysis, thereby obtaining hydrogen at the cathode and oxygen at the anode; The electrolyte is an aqueous solution containing chloride ions, and the electrolyte also includes phytic acid compounds.

7. The method according to claim 6, characterized in that: The electrolysis time is 35 to 100 h; And / or, the electrolysis current is 10-500 mA / cm 2 , voltage is 1~3V ( vs . RHE).

8. The method according to claim 6, characterized in that: The electrochemical reaction system comprises a three-electrode system and an electrolyte, wherein the three-electrode system comprises a cathode, an anode and a reference electrode; And / or, the electrochemical reaction system comprises a two-electrode system and an electrolyte, and the two-electrode system comprises a cathode and an anode.

9. The method according to claim 8, characterized in that: The cathode includes a conductive substrate; Preferably, the conductive substrate is titanium felt obtained by depositing at least any one of nickel ions, iron ions and cobalt ions; Preferably, the material of the conductive substrate includes at least any one of foamed copper, copper sheet, foamed nickel, nickel sheet, foamed cobalt, cobalt sheet, foamed iron, iron sheet, steel plate, and titanium mesh; And / or, the anode comprises at least any one of a platinum sheet or a carbon rod; And / or, the reference electrode includes at least any one of a calomel electrode or a silver / silver chloride electrode.

10. The method according to any one of claims 6 to 9, characterized in that: The Faradaic efficiency of seawater electrolysis is above 80%.

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