阅读说明：本技术 一种聚四氟乙烯的无机纳米粒子复合膜的制备方法 (Preparation method of polytetrafluoroethylene inorganic nanoparticle composite film ) 是由 王保国 万磊 于 2021-01-14 设计创作，主要内容包括：一种聚四氟乙烯的无机纳米粒子复合膜,其特征在于使用聚四氟乙烯多孔膜作为基体；将基体在硫酸亚铁的乙醇水溶液中浸渍1-10分钟；然后在氢氧化钾的乙醇水溶液中浸渍1-10分钟；此浸渍过程重复进行1-5次,促进无机纳米粒子在膜孔道内原位生长,填充聚四氟乙烯基体的膜孔,形成聚四氟乙烯的无机纳米粒子复合膜。本制膜方法能够得到耐碱性良好的阴离子交换膜,克服现有阴离子交换膜碱性稳定性差的缺点,适用于碱性电解水制取氢气,或者碱性电解水制取氧气过程。该制膜过程具有工艺简单,易于工业实施于工程放大的优点。(A polytetrafluoroethylene inorganic nanoparticle composite membrane is characterized in that a polytetrafluoroethylene porous membrane is used as a substrate; dipping the matrix in an ethanol water solution of ferrous sulfate for 1-10 minutes; then soaking in ethanol water solution of potassium hydroxide for 1-10 minutes; the dipping process is repeated for 1-5 times to promote the in-situ growth of the inorganic nano particles in the film pore channels, and the film pores of the polytetrafluoroethylene matrix are filled to form the polytetrafluoroethylene inorganic nano particle composite film. The membrane preparation method can obtain the anion exchange membrane with good alkali resistance, overcomes the defect of poor alkali stability of the existing anion exchange membrane, and is suitable for the process of preparing hydrogen by using alkaline electrolyzed water or preparing oxygen by using alkaline electrolyzed water. The film preparation process has the advantages of simple process and easy industrial implementation in engineering amplification.)

1. A polytetrafluoroethylene inorganic nanoparticle composite membrane is characterized in that the preparation process comprises the following steps;

the method comprises the following steps: using a polytetrafluoroethylene porous membrane as a substrate, immersing the substrate in an ethanol water solution, and heating;

step two: soaking the polytetrafluoroethylene porous membrane obtained in the step one in an ethanol water solution (1) of ferric chloride for 1-10 minutes;

step three: soaking the polytetrafluoroethylene porous membrane treated in the step two in an ethanol water solution (2) of potassium hydroxide for 1-10 minutes;

step four: treating the polytetrafluoroethylene porous membrane treated in the third step according to the second step method, and sequentially circulating the second step and the third step for 1-5 times;

step five: and (3) washing the polytetrafluoroethylene porous membrane obtained in the step by using deionized water, and airing at room temperature to obtain the polytetrafluoroethylene inorganic nano particle composite membrane.

2. The polytetrafluoroethylene-based inorganic nanoparticle composite membrane according to claim 1, wherein the pore size of the polytetrafluoroethylene porous membrane is 0.1-1 μm.

3. The polytetrafluoroethylene-inorganic nanoparticle composite membrane according to claim 1, wherein said aqueous ethanol solution (1) of ferric chloride can be replaced by transition metal salts, including chloride, sulfate, nitrate; other transition metals may be used in place of the iron element, including nickel, titanium, manganese, cobalt; the solution (1) can be a mixture of 1-2 transition metal salts, and the molar ratio of the two transition metal salts is 10: 0 to 0: 10; other organic solvents may be used in place of ethanol, including n-propanol, isopropanol, hexane.

4. The polytetrafluoroethylene-inorganic nanoparticle composite membrane according to claim 1, wherein sodium hydroxide is used in place of potassium hydroxide in the aqueous ethanol solution (2) of potassium hydroxide; other organic solvents may be used in place of ethanol, including n-propanol, isopropanol, hexane.

5. The polytetrafluoroethylene-inorganic nanoparticle composite membrane according to claim 1, wherein in the second step and the third step, the temperature of the solution (1) and the solution (2) is in the range of 0-80 ℃.

6. The polytetrafluoroethylene inorganic nanoparticle composite film is characterized in that: the polytetrafluoroethylene inorganic nanoparticle composite membrane prepared by the method according to claims 1 to 5, or a combination of the polytetrafluoroethylene porous membrane and polytetrafluoroethylene inorganic nanoparticle composite membrane, is used in multiple layers.

7. The polytetrafluoroethylene-based inorganic nanoparticle composite membrane according to claim 6, wherein the composite membrane is used in a water electrolysis process, including a process of producing hydrogen by electrolyzing water and a process of producing oxygen by electrolyzing water.

Technical Field

The invention belongs to the technical field of preparation of inorganic nanoparticle composite membranes, and particularly relates to a technical method for manufacturing an anion conduction membrane for alkaline electrolyzed water.

Technical Field

With the increasing exhaustion of traditional energy sources such as petroleum and coal and the increasing severity of environmental problems, the development of efficient and clean energy sources is imperative. The hydrogen has high quality and heat value, and is a more suitable energy storage medium than other fuels. The energy density of hydrogen is 140MJ/kg, more than twice that of a typical solid fuel (50 MJ/kg). The combustion of hydrogen only produces water, a feature that makes hydrogen an environmentally friendly energy storage medium.

Conventional hydrogen production techniques include reforming, decomposition, and hydrolysis of fossil fuels. However, these conventional hydrogen production processes tend to produce large amounts of greenhouse gases, which are harmful to the environment. The current water electrolysis hydrogen production technology mainly comprises alkaline electrolysis water and proton exchange membrane electrolysis water. Alkaline electrolyzed water has been commercially used due to the advantage of low cost. The operation temperature is between 60 and 80 ℃, KOH or NaOH aqueous solution is used as electrolyte, and the concentration of the electrolyte is about 20 to 30 percent. The porous diaphragm of the alkaline electrolyzed water conducts hydroxyl and blocks gas generated at two sides of the electrode. At present, asbestos cloth is used as a diaphragm in alkaline electrolyzed water. Due to the defects of high carcinogenicity, high resistance and low air-blocking property of the asbestos cloth, the alkaline electrolyzed water has low performance, and the maximum working current density is less than 500mA/cm²。

In order to improve the ionic conductivity of the membrane, the document (int. j. hydrogen Energy,2007(32):5094-5097) deposits metal Ni on a stainless steel substrate to prepare a porous inorganic membrane with controllable thickness and pore structure, thereby effectively regulating and controlling the membrane resistance. However, its macroporous structure does not meet the requirements for barrier to gas permeation. Since Polybenzimidazole (PBI) membranes have low gas permeability characteristics, the literature (J Membr Sci,2013(447): 424-. Soaking the polybenzimidazole membrane in 4mol L^-1KOH solution of (2) for several days, the hydroxyl conductivity at room temperature can be increased to 26mS cm^-1. In order to improve the ion conductivity of PBI membranes, the literature (J.Power Sources,2016(312):128-136) prepares a polybenzimidazole (ABPBI) polymer with a plurality of imidazole structural units, and the ABPBI membranes subjected to crosslinking reaction are used in alkaline electrolyzed water, and the current density reaches 335mA cm at the voltage of 2.0V^-2. To improve the mechanical stability of PBI membranes, composite membranes prepared by blending various polymeric materials with PBI for alkaline electrolysis of water include polyvinyl alcohol (J Membr Sci,2017(535):45-55), FAA3(J Membr Sci, 2018(564):653-157):71-82). Although the above studies improve the hydroxide ion conductivity and the gas barrier property to some extent, there are two general problems. 1) The membrane material is degraded when used under the strong alkali high temperature condition, thereby causing the reduction of the electrolytic performance; 2) the process of synthesizing the above polymers and inorganic membranes often involves multiple steps and is difficult to adapt to large-scale mass production.

Aiming at the defects of the ion conduction membrane preparation technology, the invention provides the following ideas: using a cheap commercial polytetrafluoroethylene microporous membrane as a substrate, and soaking the substrate in a mixed solution of an organic solvent of ferrous sulfate and water for 1-10 minutes; then dipping the mixture in a mixed solution of an organic solvent of potassium hydroxide and water for 1 to 10 minutes; the dipping process is circulated for 1-5 times, and the in-situ growth of inorganic nano-ions and the formation of the polytetrafluoroethylene inorganic nano-ion composite membrane in the membrane pore channels are promoted. The matrix material has good strong base resistance stability and flexibility, and the metal hydroxide has anion (hydroxide) exchange capacity and provides a hydroxide ion channel. The polytetrafluoroethylene inorganic nano particle composite membrane can be used as an ion conduction membrane and used in the hydrogen production process by alkaline electrolysis of water. By utilizing the characteristic of high alkali resistance of the inorganic nano particle composite membrane of the polytetrafluoroethylene, the working life of alkaline electrolyzed water can be effectively prolonged, a universal method is provided for developing novel ion conducting membrane preparation, and a foundation is laid for further industrialization.

Disclosure of Invention

The invention aims to provide a preparation method of an inorganic nano particle composite membrane of polytetrafluoroethylene, in particular to a diaphragm suitable for alkaline electrolyzed water, which is technically characterized in that the preparation process comprises the following steps;

the method comprises the following steps: using a polytetrafluoroethylene porous membrane as a substrate, immersing the substrate in an ethanol water solution, and heating;

step two: soaking the polytetrafluoroethylene porous membrane obtained in the step one in an ethanol water solution (1) of ferric chloride for 1-10 minutes;

step three: soaking the polytetrafluoroethylene porous membrane treated in the step two in an ethanol water solution (2) of potassium hydroxide for 1-10 minutes;

step four: treating the polytetrafluoroethylene porous membrane treated in the third step according to the second step method, and sequentially circulating the second step and the third step for 1-5 times;

step five: and (3) washing the polytetrafluoroethylene porous membrane obtained in the step by using deionized water, and airing at room temperature to obtain the polytetrafluoroethylene inorganic nano particle composite membrane.

The aperture of the polytetrafluoroethylene porous membrane is 0.1-1 mu m; the ethanol aqueous solution (1) of the ferric chloride can be replaced by transition metal salts, including chloride, sulfate and nitrate; other transition metals may be used in place of the iron element, including nickel, titanium, manganese, cobalt; the solution (1) can be a mixture of 1-2 transition metal salts, and the molar ratio of the two transition metal salts is 10: 0 to 0: 10; other organic solvents may be used in place of ethanol, including n-propanol, isopropanol, hexane.

In the ethanol aqueous solution (2) of potassium hydroxide, sodium hydroxide may be used instead of potassium hydroxide; other organic solvents may be used in place of ethanol, including n-propanol, isopropanol, hexane.

In the second step and the third step, the temperature ranges of the solution (1) and the solution (2) are 0-80 ℃.

A polytetrafluoroethylene-inorganic nanoparticle composite film prepared by the above method or a composite of the polytetrafluoroethylene porous film and polytetrafluoroethylene-inorganic nanoparticle composite film is used in multiple layers.

The composite membrane is used for the water electrolysis process, including the processes of preparing hydrogen by electrolyzing water and preparing oxygen by electrolyzing water.

The preparation method of the polytetrafluoroethylene inorganic nanoparticle composite ionic membrane is simple and easy for industrial amplification, avoids using a highly volatile organic solvent in the preparation process, and obviously improves the process environment conditions. The polytetrafluoroethylene inorganic nanoparticle composite ionic membrane can be used as an ionic conduction membrane for the hydrogen production process by alkaline electrolysis of water. By utilizing the characteristic of high alkali resistance of the inorganic nano particle composite ionic membrane of the polytetrafluoroethylene, the working life of alkaline electrolyzed water can be effectively prolonged, a universal method is provided for developing novel ionic conduction membrane preparation, and a foundation is laid for further industrialization.

Drawings

FIG. 1 is a flow of preparing an inorganic nanoparticle composite film of polytetrafluoroethylene;

FIG. 2 shows the technical performance of the polytetrafluoroethylene composite membrane in the process of hydrogen production by water electrolysis.

Detailed Description

The implementation steps of the invention are as follows:

1) an inexpensive commercial porous membrane is used as a base material. The substrate film was swollen in an ethanol solution for 3 hours, and then the treated substrate film was immersed in a mixed solution of an organic solvent of a transition metal salt and water, followed by immersion in a mixed solution of an organic solvent of an inorganic base and water. The dipping process is circulated for many times, and the in-situ growth of inorganic nano-ions and the formation of the polytetrafluoroethylene inorganic nano-ion composite ionic membrane in the membrane pore channels are promoted.

2) The pore diameter of the polytetrafluoroethylene porous membrane is 0.1-1 mu m, and 0.1 mu m is preferably selected.

3) The transition metal salt comprises chloride, sulfate and nitrate, preferably nitrate. 1) The transition metal can be nickel, titanium, manganese and cobalt, and the metal nickel is preferably selected. In addition, the transition metal salt can be a mixture of 1-2 transition metal salts, and the molar ratio of the two transition metal salts is 10: 0 to 0: preferably, nickel nitrate and ferrous sulfate are selected, and the molar ratio of nickel nitrate to ferrous sulfate is 1: 1. 1) the organic solvent in the transition metal salt solution described in (1) may be ethanol, n-propanol, isopropanol and hexane, preferably ethanol.

4) The inorganic base can be potassium hydroxide and sodium hydroxide, preferably potassium hydroxide. 1) The organic solvent in the inorganic alkali solution described in (1) may be ethanol, n-propanol, isopropanol and hexane, with ethanol being preferred.

5) The temperature range of the impregnation is 0-80 ℃, and room temperature is preferably selected.

6) The cycle times of the dipping process are 1-5 times, and 3 times are preferably selected.

7) Using a plurality of layers of the polytetrafluoroethylene inorganic nanoparticle composite ionic membrane prepared by the method described in 1), or a combination of the polytetrafluoroethylene porous membrane and the polytetrafluoroethylene inorganic nanoparticle composite ionic membrane described in 1).

8) The polytetrafluoroethylene inorganic nanoparticle composite ionic membrane prepared by the method can be used in the water electrolysis process, including the processes of preparing hydrogen by electrolyzing water and preparing oxygen by electrolyzing water.

A porous polytetrafluoroethylene membrane having a pore size of 0.1 μm was immersed in a beaker of ethanol and heated at 60 ℃ for 3 hours. Then, at room temperature, the swollen polytetrafluoroethylene membrane was immersed in a solution of 1: 1, and 1, adding the mixed solution of nickel nitrate and ferrous sulfate in ethanol and water for 1-10 minutes. And then, soaking the treated polytetrafluoroethylene membrane into a mixed solution of ethanol and water of potassium hydroxide for 1-10 minutes. The dipping process is circulated for 3 times, then deionized water is used for cleaning for 3-5 times, and then the inorganic nano ion composite membrane is dried at room temperature, so that the required polytetrafluoroethylene inorganic nano ion composite membrane can be obtained.

TABLE I example of inorganic nano-ionic composite membrane of polytetrafluoroethylene

Note: measuring hydroxyl conductivity of the membrane by AC impedance method, placing the membrane in a self-made conductivity cell, and charging 1.0mol L of the membrane on both sides^-1With a scanning frequency of 100-10⁶HZ, alternating voltage is 10 mV.

Hydroxyl conductivity test of the membrane using a multi-layer inorganic nanoparticle composite ionic membrane of polytetrafluoroethylene prepared by the method described in 1), the hydroxyl conductivity of the two-layer membrane was 5.0mS cm^-1(ii) a The hydroxide conductivity of the three-layer film was 3.7mScm^-1。

In the above example, an alkali-resistant stable polytetrafluoroethylene porous membrane is used as a substrate, and the substrate is immersed in a mixed solution of an organic solvent of ferrous sulfate and water for 1 to 10 minutes; then dipping the mixture in a mixed solution of an organic solvent of potassium hydroxide and water for 1 to 10 minutes; the dipping process is circulated for 1-5 times, and the in-situ growth of inorganic nano-ions and the formation of the polytetrafluoroethylene inorganic nano-ion composite ionic membrane in the membrane pore channels are promoted. As shown in fig. 2, the assembly of the inorganic nanoparticle composite ionic membrane of 1 to 3 layers of polytetrafluoroethylene was used in alkaline electrolyzed water, and exhibited good electrolyzed water performance.