A method for preparing a proton exchange membrane electrochemical oxygen and nitrogen production membrane electrode

Abstract

The application relates to a preparation method of a proton exchange membrane electrochemical oxygen production and nitrogen production membrane electrode, which comprises an anode catalytic layer, a proton exchange membrane and a cathode catalytic layer which are stacked in sequence, aims to provide a high-efficiency membrane electrode applied to an oxygen generator or a nitrogen generator, and can solve the problems of low running current density and low production efficiency in the electrochemical oxygen production and nitrogen production process. The membrane electrode is used in the proton exchange membrane electrochemical oxygen production and nitrogen production process, has the characteristics of low running voltage and high current density stable operation, and can be used as a fuel cell membrane electrode due to the same structure of the membrane electrode and the fuel cell membrane electrode and the fact that the catalytic layer contains a fuel cell catalyst. Specifically, the anode and the cathode of the membrane electrode prepared by using a spraying method are an iridium-based catalyst and a platinum-carbon catalyst, and can realize 1.4V@1A / cm 2 current density operation. The prepared membrane electrode has the characteristics of simple preparation method and uniform electrode structure, and can realize miniaturization, low cost and high-efficiency stable operation of a PEM electrochemical oxygen production and nitrogen production device.

Description

Technical Field

[0001] This invention relates to the field of oxygen and nitrogen preparation, and particularly to a method for preparing a proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode. Background Technology

[0002] Oxygen is not only essential for the survival of many living organisms, but also an indispensable industrial raw material in modern society. Oxygen has applications in industries such as metallurgy and chemicals, in the medical field of treating respiratory diseases, and in home healthcare. There are two main methods for large-scale industrial oxygen production: pressure swing adsorption (PSA) and cryogenic separation. For small-scale applications such as home use, while cryogenic separation offers advantages such as high product purity, low energy consumption, and the ability to simultaneously produce byproducts, its cost is significantly impacted by economies of scale due to investment and process limitations, making miniaturization impossible. While PSA can be miniaturized, the system is relatively complex, generates significant noise, and produces lower product purity. Chemical oxygen production methods, although not limited by equipment size, often use raw materials with strong oxidizing properties, posing potential dangers during transportation and use.

[0003] Electrochemical oxygen generation is a method similar to PEM water electrolysis. Pressurized air is introduced to the cathode side. Under the influence of the potential difference, an oxygen reduction reaction occurs at the cathode, consuming oxygen from the air, while an oxygen evolution reaction occurs at the anode, generating high-purity oxygen. This oxygen generation method is simple in structure, highly adaptable to large-scale applications, and is safer than chemical oxygen generation because it does not produce hydrogen and does not require the use of hazardous chemical reagents. Simultaneously, since the oxygen on the air side is consumed, the remaining gas is mainly nitrogen. Under suitable air flow conditions, low-purity nitrogen can be produced simultaneously, which can be used in some scenarios or further purified. As the electrochemical oxygen generation process is the reverse reaction of the fuel cell power generation process, its catalyst is also suitable for fuel cell reaction catalysis; therefore, its membrane electrode assembly (MEA) can often be used as a fuel cell MEA. Summary of the Invention

[0004] This invention mainly proposes a method for preparing a proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode, aiming to provide a high-efficiency membrane electrode that can be used in oxygen generators or nitrogen generators and can also be used as a fuel cell membrane electrode.

[0005] This invention solves the problems of low operating current density and low production efficiency in electrochemical oxygen and nitrogen generation processes. The invention employs a spray coating method to prepare the anode and cathode of the membrane electrode assembly (MEA), with an iridium-based catalyst at the anode and a platinum-based catalyst at the cathode, achieving operation at a current density of 1.4V@1A / cm². The invented MEA preparation method is characterized by its simple operation and uniform electrode structure, enabling miniaturization, low cost, and efficient and stable operation of PEM electrochemical oxygen and nitrogen generation. Simultaneously with oxygen generation, low-purity nitrogen gas with a concentration of over 90% is produced, which can be used directly or after further purification. Furthermore, since this MEA has the same structure as a fuel cell MEA and its catalyst layer contains fuel cell catalysts, it can be used as a fuel cell MEA.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode, the membrane electrode comprising an anode catalyst layer, a proton exchange membrane, and a cathode catalyst layer.

[0008] The proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode is characterized in that the slurry used to prepare the anode catalyst layer comprises the following components: anode catalyst, dispersing solvent, hydrophobic agent, pore-forming agent, and perfluorosulfonic acid solution.

[0009] The proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode is characterized in that: the anode catalyst is one or more of platinum, iridium nanomaterials, alloys or oxides.

[0010] The proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode is characterized in that the slurry used to prepare the cathode catalyst layer includes the following components: cathode catalyst, dispersing solvent, hydrophobic agent, pore-forming agent and perfluorosulfonic acid solution.

[0011] The proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode is characterized in that: the cathode catalyst is a Pt-based catalyst.

[0012] The proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode slurry is characterized in that: the dispersing solvent is one or more of water, methanol, ethanol, isopropanol and n-propanol.

[0013] The slurry used to prepare the anode / cathode catalyst layer is characterized in that the hydrophobic agent is one or more of polytetrafluoroethylene, polypropylene, polyvinylidene fluoride, and fluorinated ethylene propylene.

[0014] The slurry used to prepare the anode / cathode catalyst layer is characterized in that the pore-forming agent is one or more of ammonium oxalate, ammonium nitrate, and ammonium bicarbonate.

[0015] Preferably, the preparation of the anode catalyst slurry includes the following steps: weighing a certain mass of catalyst, adding dispersing solvents water and alcohol, the mass of the solvent being 50 to 150 times that of the catalyst, the mass ratio of water to alcohol being 2:1 to 1:2, adding 5% to 20% Nafion solution, the mass of Nafion being 1 / 15 to 1 / 5 of the catalyst mass, adding a hydrophobic agent, the mass of the hydrophobic agent being 1 / 60 to 1 / 10 of the catalyst mass, adding a pore-forming agent, the mass of the pore-forming agent being 1 / 50 to 1 / 10 of the catalyst mass, sonicating for 5 to 30 minutes, and dispersing for 0.5 to 2 hours using a disperser at a speed of 10 to 30 krpm.

[0016] Preferably, the preparation of the cathode catalyst slurry includes the following steps: weighing a certain mass of catalyst, adding dispersing solvents water and alcohol, the mass of the solvent being 30 to 100 times that of the catalyst, the mass ratio of water to alcohol being 2:1 to 1:2, adding a hydrophobic agent, the mass of the hydrophobic agent being 1 / 60 to 1 / 10 of the catalyst mass, adding a pore-forming agent, the mass of the pore-forming agent being 1 / 50 to 1 / 10 of the catalyst mass, sonicating for 5 to 30 minutes, stirring for 5 to 30 minutes, sonicating for 5 to 30 minutes, adding 5% to 20% Nafion solution, the mass of Nafion being 1 / 8 to 1 / 3 of the catalyst mass, stirring for 5 to 30 minutes, and sonicating for 5 to 30 minutes.

[0017] The method for preparing the proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode is characterized by the following steps: spraying an anode catalyst slurry onto one side of the proton exchange membrane, spraying a cathode catalyst slurry onto the other side, and then drying.

[0018] The method for preparing the proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode is characterized in that: the iridium loading of the anode catalyst is 0.4~2 mg·cm³. -2 The platinum loading of the cathode catalyst is 0.2~0.5 mg·cm³. -2 .

[0019] The application of the proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode is characterized in that it is used in the PEM electrochemical oxygen and nitrogen generation process.

[0020] Preferably, the spraying process is carried out on a negative pressure hot plate at a temperature of 60~90℃. The negative pressure on the spraying plate adsorbs the membrane onto the surface of the spraying plate to ensure the smoothness of the membrane surface. The spraying equipment uses an ultrasonic sprayer to spray a certain amount of cathode slurry and anode slurry onto both sides of the proton exchange membrane, respectively.

[0021] Compared to existing technologies, this invention can operate at higher current densities. This invention can increase the operating current density to 1 A / cm². 2@1.4V not only reduces energy consumption and improves energy utilization, but also allows the reaction system to be arranged in a denser structure and smaller space, improving the portability of the equipment. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0023] Figure 1 This is a schematic diagram of the single-cell polarization curve of Embodiment 1 of this application.

[0024] Figure 2 This is a schematic diagram of the single-cell polarization curve of Comparative Example 1 of this application. Detailed Implementation

[0025] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments. Unless otherwise specified, the raw materials and catalysts in the embodiments of the present application are all purchased through commercial channels.

[0026] Example 1

[0027] 1. Weigh 1g of anode catalyst, add 50g of water, 50g of ethanol and 0.7g of 20% Nafion solution, sonicate for 5min, and disperse for 1h using a disperser at 20krpm.

[0028] 2. Weigh 1g of cathode catalyst, add 25g of ethanol and 75g of isopropanol, stir for 10min, sonicate for 30min, add 1.8g of 20% Nafion solution, stir for 10min, sonicate for 30min.

[0029] 3. Flatten the proton exchange membrane on a negative pressure heating table, and spray anolyte onto one side of the proton exchange membrane until its iridium loading reaches 1.2 mg·cm³. -2 Flip the proton exchange membrane and spray cathode slurry onto the other side of the membrane until its platinum loading reaches 0.35 mg·cm³. -2 After spraying, place on a hot plate to dry for 5 minutes.

[0030] Example 2

[0031] 1. Weigh 1g of anode catalyst, add 30g of water, 20g of ethanol and 0.4g of 20% Nafion solution, sonicate for 5min, and disperse using a disperser at 10krpm for 40min.

[0032] 2. Weigh 1g of cathode catalyst, add 20g of ethanol, 12g of isopropanol and 0.1g of 60% PTFE emulsion, stir for 5min, sonicate for 10min, add 0.5g of 20% Nafion solution, stir for 5min, sonicate for 10min.

[0033] 3. Flatten the proton exchange membrane on a negative pressure heating table, and spray anolyte onto one side of the proton exchange membrane until its iridium content reaches 0.4 mg·cm³. -2 Flip the proton exchange membrane and spray the cathode slurry onto the other side of the proton exchange membrane until its platinum loading reaches 0.2 mg·cm³. -2 After spraying, place on a hot plate to dry for 5 minutes.

[0034] Example 3

[0035] 1. Weigh 1g of anode catalyst, add 50g of water, 90g of ethanol and 0.8g of 20% Nafion solution, add 0.1g of ammonium bicarbonate, sonicate for 25min, and disperse for 1.5h using a disperser at 28krpm.

[0036] 2. Weigh 1g of cathode catalyst, add 36g of ethanol and 36g of isopropanol, stir for 10min, sonicate for 30min, add 1.5g of 20% Nafion solution, stir for 20min, sonicate for 30min.

[0037] 3. Flatten the proton exchange membrane on a negative pressure heating table, setting the table temperature to 90℃. Spray the anolyte slurry onto one side of the proton exchange membrane until its iridium content reaches 1.8 mg·cm³. -2 Flip the proton exchange membrane and spray cathode slurry onto the other side of the membrane until its platinum loading reaches 0.46 mg·cm³. -2 After spraying, place on a hot plate to dry for 5 minutes.

[0038] Comparative Example 1

[0039] The difference from Example 1 is that during the single-cell test, the cathode inlet is closed and no air is introduced.

[0040] Performance testing

[0041] The proton exchange membrane electrodes prepared in Example 1 and Comparative Example 1 were respectively assembled into 5cm 2 A single electrolytic cell was used, and its polarization curve was measured at 80°C with a cathode air flow rate of 65 m³ / min and an anode deionized water flow rate of 20 ml / min. The obtained single-cell polarization curves are shown below. Figure 1 and Figure 2 As shown.

[0042] Comparative Example 1 and Comparative Example 1 show that the electrolyzer assembled with the membrane electrode of the present invention can produce oxygen at a lower voltage, with high operating efficiency and sufficient safety assurance. Its starting voltage of 0.61V is much lower than the voltage of 1.47V in the comparative example. This indicates that the present invention has a lower operating voltage and lower oxygen production power compared to water electrolysis for oxygen and hydrogen production, which is beneficial for the low cost, portability and miniaturization of oxygen production equipment.

[0043] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode, characterized in that, The membrane electrode includes an anode catalytic layer, a proton exchange membrane, and a cathode catalytic layer; The slurry used to prepare the anode catalyst layer includes the following components: anode catalyst, dispersion solvent, hydrophobic agent, pore-forming agent, and perfluorosulfonic acid solution; Slurry used to prepare cathode catalyst layer It includes the following components: cathode catalyst, dispersing solvent, hydrophobic agent, pore-forming agent, and perfluorosulfonic acid solution; The preparation method of the slurry used to prepare the anode catalyst layer includes the following steps: weigh a certain mass of anode catalyst, add dispersing solvent water and alcohol, the mass of the solvent is 20 to 150 times that of the anode catalyst, the mass ratio of water to alcohol is 2:1 to 1:2, add 5% to 20% Nafion solution, the mass of Nafion is 1 / 15 to 1 / 3 of the mass of the anode catalyst, add hydrophobic agent, the mass of hydrophobic agent is 1 / 60 to 1 / 10 of the mass of the anode catalyst, add pore-forming agent, the mass of pore-forming agent is 1 / 50 to 1 / 10 of the mass of the anode catalyst, sonicate for 5 to 30 min, and disperse using a disperser at a speed of 10 to 30 k rpm for 0.5 to 2 h; Preparation method of slurry used to prepare cathode catalyst layer The process includes the following steps: Weigh a certain mass of cathode catalyst, add dispersing solvents water, ethanol, and isopropanol, with the solvent mass being 10 to 100 times that of the cathode catalyst and the ethanol to isopropanol mass ratio being 2:1 to 1:2; add a hydrophobic agent, with the hydrophobic agent mass being 1 / 60 to 1 / 10 of the cathode catalyst mass; add a pore-forming agent, with the pore-forming agent mass being 1 / 50 to 1 / 10 of the cathode catalyst mass; sonicate for 5 to 30 minutes; stir for 5 to 30 minutes; sonicate for 5 to 30 minutes; add 5% to 20% Nafion solution, with the Nafion mass being 1 / 10 to 1 / 2 of the cathode catalyst mass; stir for 5 to 30 minutes; sonicate for 5 to 30 minutes.

2. The proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode according to claim 1, characterized in that, The anode catalyst is one or more of platinum, iridium nanomaterials, alloys, or oxides.

3. The proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode according to claim 1, characterized in that, The cathode catalyst is a Pt-based catalyst.

4. The proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode according to claim 1, characterized in that, The hydrophobic agent is one or more of polytetrafluoroethylene, polypropylene, polyvinylidene fluoride, and fluorinated ethylene propylene.

5. The proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode according to claim 1, characterized in that, The pore-forming agent is one or more of ammonium oxalate, ammonium nitrate, and ammonium bicarbonate.

6. A method for preparing a proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode as described in claim 1, characterized in that, The preparation method includes the following steps: spraying a slurry for preparing an anode catalyst layer onto one side of the proton exchange membrane, spraying a slurry for preparing a cathode catalyst layer onto the other side, and then drying.

7. The method for preparing the proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode according to claim 6, characterized in that, The iridium loading of the anode catalyst is 0.4~4 mg·cm³. -2 The platinum loading of the cathode catalyst is 0.2~0.5 mg·cm³. -2 .

8. The application of a proton exchange membrane electrochemical oxygen and nitrogen generation membrane electrode prepared by any one of the methods described in claims 1-5 and / or any one of the methods described in claims 6-7 in the PEM electrochemical oxygen and nitrogen generation process.

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