CN103474688A - Nano cerium oxide-modified sulfonated polyphenylene sulfide proton exchange membrane and preparation method thereof - Google Patents

Abstract

The invention relates to a nano cerium oxide-modified sulfonated polyphenylene sulfide proton exchange membrane and a preparation method thereof. The proton exchange membrane comprises the following components by mass percent: 82.5-99.9% of stable protein plasma solution (SPPS) of which the sulfonation degree is 57-80%, and 0.1-17.5% of nano CeO2 powder. The method disclosed by the invention comprises the following steps: with the SPPS as a base body and rare-earth metal oxide nano CeO2 as a filling phase, preparing an evenly mixed membrane casting solution, and then adopting a curtain coating or pressing and film-forming method to prepare an inorganic-organic composite film in a drying manner. The proton exchange membrane is low in preparation cost; the prepared SPPS/CeO2 proton exchange membrane is high in conductivity, and excellent in methanol permeability; the conductivity at 40-110 DEG C is 8.0*10<-3>-1.8*10<-2> S/cm; the alcohol resistance coefficient reaches 1.1*10<-8>-6.6*10<-7>cm<2>/s; the water absorption is 22.49-70.12%.

Description

Nano cerium oxide modified sulfonated polyphenylene sulfide proton exchange membrane and preparation method thereof

technical field

The invention relates to a sulfonated polyphenylene sulfide proton exchange membrane and a preparation method thereof, in particular to a nanometer cerium oxide modified sulfonated polyphenylene sulfide proton exchange membrane and a preparation method thereof.

Background technique

Proton exchange membrane (PEM) is the core part of direct methanol fuel cell (DMFC), which is a hot spot in the current energy research and development. Its material must have good proton conductivity, suitable methanol permeability and good water swelling resistance. The proton conductivity should reach at least 10 ^-2 S/cm, and the methanol permeability coefficient should be lower than 10 ^-6 cm ² /s. Make the proton exchange membrane have a long service life in DMFC.

At present, the most widely used perfluorosulfonic acid membrane is represented by the Nafion membrane commercialized by DuPont Company of the United States. Long-term use of this fluoride will seriously pollute the environment. When the operating temperature exceeds 80 °C, the proton conductivity will drop significantly. The further application of perfluorosulfonic acid membranes in fuel cells is limited. Therefore, it is necessary to further prepare proton exchange membranes with excellent comprehensive performance.

Sulfonated polyphenylene sulfide (SPPS) material has become a key research material for proton exchange membranes for direct methanol fuel cells because of its high mechanical strength, excellent thermal stability and chemical stability. Use concentrated sulfuric acid to sulfonate polyphenylene sulfide, and introduce sulfonic acid groups into the main chain of polyphenylene sulfide. Due to the presence of sulfonic acid group hydrophilic phase and hydrophobic phases such as benzene rings and carbon-sulfur bonds on the polymer backbone , can make the polyphenylene sulfide material have a certain proton conductivity, and the polyphenylene sulfide has low preparation cost and excellent heat resistance stability, which can meet the requirements of the fuel cell for the proton exchange membrane material. However, the sulfonation degree (DS) of this material will directly affect the performance of the proton exchange membrane, so an appropriate sulfonation degree should be selected for doping to form a membrane. In the scheme design of sulfonated polyphenylene sulfide proton exchange membrane, it is usually necessary to comprehensively consider the sulfonation degree and modification method of sulfonated polyphenylene sulfide to obtain the best proton exchange membrane.

Contents of the invention

One of the objectives of the present invention is to provide a nanometer cerium oxide (CeO ₂ ) modified sulfonated polyphenylene sulfide proton exchange membrane.

The second object of the present invention is to provide a preparation method of the proton exchange membrane.

To achieve the above object, the present invention adopts the following technical solutions:

A nano-cerium oxide modified sulfonated polyphenylene sulfide proton exchange membrane, characterized in that the composition and mass percentage of the exchange membrane are:

Sulfonated polyphenylene sulfide SPPS 82.5%~99.9%;

Nano CeO ₂ powder 0.1%～17.5%;

The structural formula of the sulfonated polyphenylene sulfide SPPS is:

；

;

The particle size of the CeO ₂ powder is 25-30 nm.

The sulfonation degree of the above-mentioned sulfonated polyphenylene sulfide is 57%-80%.

A method for preparing the above-mentioned nano-cerium oxide modified sulfonated polyphenylene sulfide proton exchange membrane, characterized in that the specific steps of the method are:

(1). Dissolving sulfonated polyphenylene sulfide in a membrane-forming solvent to prepare a membrane-forming solution with a concentration of 10% to 50% by mass;

(2). In the film-making solution obtained in the above step (1), add nano- _CeO2 powder, and stir at 20 °C to 80 °C to make the nano- _CeO2 powder uniformly dispersed in the film-making liquid to obtain a mixed system Membrane fluid;

(3). The mixed film-making solution obtained in step (2) is made into a film, and then the solvent is volatilized at 20 ° C to 90 ° C to obtain a wet film;

(4). Dry the wet film obtained in step (3) at a constant temperature of 50 °C to 180 °C for 1 h to 24 h; or first dry at 40 °C to 110 °C for 2 h to 24 h, and then heat up to Dry at 120 °C to 180 °C for 1 h to 7 h to obtain nano-cerium oxide modified sulfonated polyphenylene sulfide proton exchange membrane.

The above-mentioned method for preparing a modified medium-high sulfonated polyphenylene sulfide proton exchange membrane is characterized in that the membrane-making solvent used is: N,N-dimethylsulfoxide DMSO or N,N-dimethylacetamide DMAC.

The degree of sulfonation refers to the number of sulfonic acid groups contained in every 100 repeating units in SPPS.

Detailed ways

Embodiment one:

1. Preparation of SPPS film-making solution: DMSO was used as the film-making solution, and the ground SPPS material with a sulfonation degree of 70.2% was dissolved in the film-making solvent to prepare a film-making solution with a mass percentage of SPPS of 10%.

2. Preparation of SPPS/nano- _CeO2 film-making solution: In the SPPS film-making solution obtained in step 1, add nano- _CeO2 powder at a dose of 6% by mass, and its particle size is 25 nm. Stir with a magnetic stirrer at 30 °C for 4 h, and at 75 °C for 6 h to disperse the nano- _CeO2 powder evenly in the film-forming solution to obtain the SPPS/nano- _CeO2 film-forming solution.

3. Preparation of SPPS/nano-CeO ₂ proton exchange membrane: pour the mixed membrane-making solution obtained in step 2 into a clean flat mold and cast it into a membrane. The mixed film-making solution in the mold was volatilized at 50 °C to obtain a SPPS/ _CeO2 wet film. The wet film was first dried at 60 °C for 2 h, and then heated to 120 °C for 2 h to obtain the SPPS/ _CeO2 dry film.

The SPPS/ _CeO that above-mentioned embodiment is made Proton exchange membrane is applied to experiment, and its process and result are as follows:

1. SPPS/ CeO ₂ proton exchange membrane conductivity test:

Based on the improvement of the AC two-electrode method, a simple and reliable membrane resistance testing device was designed and established by ourselves. The detection temperature ranges from 40 °C to 110 °C. The electrical conductivity of the SPPS/CeO ₂ film is 8.0×10 ^-3 S/cm at 40 °C and 9.0×10 ^-3 S/cm at 110 °C.

2. SPPS/ CeO ₂ proton exchange membrane alcohol resistance performance test:

The alcohol-repellent properties of the membranes were evaluated using a diaphragm diffusion cell. Before the test, the membrane samples were soaked in deionized water for one day, and the test was carried out after stabilizing at the test temperature for more than 2 h. The membrane is sandwiched between the two half chambers, 80 ml of 5 mol/L methanol solution is injected into one side, and a considerable volume of pure water is injected into the other side so that its liquid level is equal to that of methanol. Gas chromatography was used to measure the change of methanol concentration in pure water with time. According to Fick's second law of diffusion, the methanol permeation coefficient can be obtained:

s: the slope of the methanol concentration versus time curve

V ₂ : volume of pure water

l: wet film thickness

A: Membrane area

C: initial concentration of methanol solution

Through experiments, under the above reaction conditions, the alcohol inhibition coefficient of the SPPS/CeO ₂ film is 1.1×10 ^-8 cm ² /s.

3. SPPS/ CeO ₂ proton exchange membrane water absorption test:

The SPPS membrane was first dried at 110 °C for 24 h, and the dry membrane weight (M _d ) was weighed, and then the membrane was immersed in deionized water for 24 h at room temperature to fully swell. Take out the wet film, absorb the surface moisture, and weigh the wet film (M _w ), the water absorption rate S _w of the film is:

According to the test, under the above reaction conditions, the water absorption rate of the SPPS/ _CeO2 proton exchange membrane is 70.12%.

Embodiment two:

1. Preparation of SPPS film-making solution: DMSO was used as the film-making solution, and the ground SPPS material with a sulfonation degree of 72.1% was dissolved in the film-making solvent to prepare a film-making solution with a mass percentage of SPPS of 10%.

2. Preparation of SPPS/nano- _CeO2 film-making solution: In the SPPS film-making solution obtained in step 1, add nano- _CeO2 powder at a dose of 10% by mass, and its particle size is 25 nm. Stir with a magnetic stirrer at 30 °C for 4 h, and at 75 °C for 6 h to disperse the nano- _CeO2 powder evenly in the film-forming solution to obtain the SPPS/nano- _CeO2 film-forming solution.

3. Preparation of SPPS/nano-CeO ₂ proton exchange membrane: pour the mixed membrane-making solution obtained in step 2 into a clean flat mold and cast it into a membrane. The mixed film-making solution in the mold was volatilized at 50 °C to obtain a SPPS/ _CeO2 wet film. The wet film was first dried at 60 °C for 2 h, and then heated to 120 °C for 2 h to obtain the SPPS/ _CeO2 dry film.

To the SPPS/ _CeO that above-mentioned embodiment makes Proton exchange membrane application experiment, its process and result are as follows:

1. SPPS/ CeO ₂ proton exchange membrane conductivity test:

The test method is as described in Example 1. The electrical conductivity of the SPPS/ CeO ₂ film is 8.1×10 ^-3 S/cm at 40 °C and 1.1×10 ^-2 S/cm at 110 °C.

2. SPPS/ CeO ₂ proton exchange membrane alcohol resistance performance test:

The test method is as described in Example 1. The alcohol inhibition coefficient of SPPS/ CeO ₂ film is 4.2×10 ^-7 cm ² /s.

3. SPPS/ CeO ₂ proton exchange membrane water absorption test:

The test method is as described in Example 1. The water absorption rate of SPPS/ _CeO2 proton exchange membrane is 48.69%

Embodiment three:

1. Preparation of SPPS film-forming solution: DMAc was used as the film-forming solution, and the ground SPPS material with a sulfonation degree of 74.8% was dissolved in the film-forming solvent to prepare a film-forming solution with a mass percentage of SPPS of 20%.

2. Preparation of SPPS/nano- _CeO2 film-making solution: In the SPPS film-making solution obtained in step 1, add nano- _CeO2 powder at a dose of 14.5% by mass, and its particle size is 30 nm. Stir with a magnetic stirrer at 30 °C for 4 h, and at 75 °C for 6 h to disperse the nano- _CeO2 powder evenly in the film-forming solution to obtain the SPPS/nano- _CeO2 film-forming solution.

3. Preparation of SPPS/nano-CeO ₂ proton exchange membrane: pour the mixed membrane-making solution obtained in step 2 into a clean flat mold and cast it into a membrane. The mixed film-making solution in the mold was volatilized at 50 °C to obtain a SPPS/ _CeO2 wet film. The wet film was first dried at 60 °C for 2 h, and then heated to 120 °C for 2 h to obtain the SPPS/ _CeO2 dry film.

To the SPPS/ _CeO that above-mentioned embodiment makes Proton exchange membrane application experiment, its process and result are as follows:

1. SPPS/ CeO ₂ proton exchange membrane conductivity test:

The test method is as described in Example 1. The electrical conductivity of the SPPS/CeO ₂ film is 8.5×10 ^-3 S/cm at 40 °C and 1.5×10 ^-2 S/cm at 110 °C.

2. SPPS/ CeO ₂ proton exchange membrane alcohol resistance performance test:

The test method is as described in Example 1. The alcohol inhibition coefficient of SPPS/ CeO ₂ film is 1.9×10 ^-8 cm ² /s.

3. SPPS/ CeO ₂ proton exchange membrane water absorption test:

The test method is as described in Example 1. The water absorption rate of SPPS/ CeO ₂ proton exchange membrane is 34.31%

Embodiment four:

1. Preparation of SPPS film-forming solution: DMAc was used as the film-forming solution, and the ground SPPS material with a sulfonation degree of 76.7% was dissolved in the film-forming solvent to prepare a film-forming solution with a mass percentage of SPPS of 20%.

2. Preparation of SPPS/nano- _CeO2 film-making solution: In the SPPS film-making solution obtained in step 1, add nano- _CeO2 powder at a dose of 17.1% by mass, and its particle size is 30 nm. Stir with a magnetic stirrer at 30 °C for 4 h, and at 75 °C for 6 h to disperse the nano- _CeO2 powder evenly in the film-forming solution to obtain the SPPS/nano- _CeO2 film-forming solution.

3. Preparation of SPPS/nano-CeO ₂ proton exchange membrane: pour the mixed membrane-making solution obtained in step 2 into a clean flat mold and cast it into a membrane. The mixed film-making solution in the mold was volatilized at 50 °C to obtain a SPPS/ _CeO2 wet film. The wet film was first dried at 60 °C for 2 h, and then heated to 120 °C for 2 h to obtain the SPPS/ _CeO2 dry film.

To the SPPS/ _CeO that above-mentioned embodiment makes Proton exchange membrane application experiment, its process and result are as follows:

1. SPPS/ CeO ₂ proton exchange membrane conductivity test:

The test method is as described in Example 1. The conductivity of the SPPS/ CeO ₂ film is 8.9×10 ^-3 S/cm at 40 °C and 1.7×10 ^-2 S/cm at 110 °C.

2. SPPS/ CeO ₂ proton exchange membrane alcohol resistance performance test:

The test method is as described in Example 1. The alcohol inhibition coefficient of SPPS/ CeO ₂ film is 1.2×10 ^-8 cm ² /s.

3. SPPS/ CeO ₂ proton exchange membrane water absorption test:

The test method is as described in Example 1. The water absorption rate of SPPS/ CeO ₂ proton exchange membrane is 24.98%.

Claims (4)

1. A nano-cerium oxide modified sulfonated polyphenylene sulfide proton exchange membrane, characterized in that the composition of the exchange membrane and its mass percentage are: Sulfonated polyphenylene sulfide SPPS 82.5%~99.9%; Nano CeO ₂ powder 0.1%～17.5%; The structural formula of the sulfonated polyphenylene sulfide SPPS is:

; The particle size of the CeO ₂ powder is 25-30 nm. 2. The nano-cerium oxide modified sulfonated polyphenylene sulfide proton exchange membrane according to claim 1, characterized in that the sulfonation degree of the sulfonated polyphenylene sulfide is 57%-80%. 3. a method for preparing nano-cerium oxide modified sulfonated polyphenylene sulfide proton exchange membrane according to claim 1 or 2, is characterized in that the concrete steps of the method are: (1). Dissolving sulfonated polyphenylene sulfide in a membrane-forming solvent to prepare a membrane-forming solution with a concentration of 10% to 50% by mass; (2). In the film-making solution obtained in the above step (1), add nano- _CeO2 powder, and stir at 20 °C to 80 °C to make the nano- _CeO2 powder uniformly dispersed in the film-making liquid to obtain a mixed system Membrane fluid; (3). The mixed film-making solution obtained in step (2) is made into a film, and then the solvent is volatilized at 20 ° C to 90 ° C to obtain a wet film; (4). Dry the wet film obtained in step (3) at a constant temperature of 50 °C to 180 °C for 1 h to 24 h; or first dry at 40 °C to 110 °C for 2 h to 24 h, and then heat up to Dry at 120 °C to 180 °C for 1 h to 7 h to obtain nano-cerium oxide modified sulfonated polyphenylene sulfide proton exchange membrane. 4. according to the preparation method of the high sulfonation degree sulfonated polyphenylene sulfide proton exchange membrane in the described modification of claim 3, it is characterized in that used film-making solvent is: N, N-dimethyl sulfoxide DMSO or N, N-Dimethylacetamide DMAC.