The preparation method of a kind of phospho-wolframic acid-polyimide compound proton exchange membrane
Technical field
The present invention relates to the preparation method of a kind of phospho-wolframic acid-polyimide compound proton exchange membrane, belong to the battery electrolyte Material Field.
Background technology
Direct methanol fuel cell (DMFC) is the Proton Exchange Membrane Fuel Cells take liquid methanol as fuel, owing to having the advantages such as fuel is cheap and easy to get, specific energy is high, fuel handling is convenient, environmental pollution is little, having obtained paying close attention to widely as novel power supply in recent years.
Yet, chemical stability is good, the advantages such as proton conductivity is high, long service life although the Nafion film of now direct methanol fuel cell use has, but, it is not only expensive, but also exist high temperature proton membrane poor stability, shortcoming that methanol permeability is high, and these two shortcomings increase along with the rising of temperature, can not satisfy the requirement that the high temperature direct methanol fuel cell is used proton membrane.
Therefore, how improving the high temperature proton conduction speed of proton exchange membrane, reduce its methanol permeability, develop the stable novel proton exchange membranes of temperature in the high-performance and low-cost, is a great technical barrier of warm direct methanol fuel cell in the exploitation.
The researchist concentrates on the research emphasis of this types of fuel cells on the organic-inorganic compoiste proton exchange film at present one after another.
Polyimide (PI) is a kind of nitrogenous heterocyclic alkaline polymer, and its excellent combination property has the advantages such as compact structure, thermostability are high, stable chemical nature, becomes one of important body material of temperature proton exchange film in the preparation.
The doping inorganics is the effective way that improves at present the film high-temp. proton conductivity, and inorganic proton conductive body such as heteropolyacid (phospho-wolframic acid, silicotungstic acid, phospho-molybdic acid etc.) ionic conductivity is very high, and does not need too much to rely on the existence of moisture, therefore receives publicity.
Heteropolyacid is the general name of the condensation oxygen acid that made by different oxygen acid condensations.Be the protonic acid of even intensity, and redox ability is arranged.By changing molecular composition, can regulate strength of acid and redox property.But heteropolyacid has water-soluble preferably, and under the condition of middle temperature DMFC operation, heteropolyacid is easy to run off with the water that electrode generates.
Can the losing issue that therefore, how to solve heteropolyacid becomes this class film become the key issue that substitutes the Nafion film.
Summary of the invention
The technical issues that need to address of the present invention just are to overcome the defective of prior art, and the preparation method of a kind of phospho-wolframic acid-polyimide compound proton exchange membrane is provided, and the film cost of the inventive method preparation is low, is evenly distributed, and specific conductivity and alcohol-resistant performance significantly improve.
For addressing the above problem, the present invention adopts following technical scheme:
The invention provides the preparation method of a kind of phospho-wolframic acid-polyimide compound proton exchange membrane, phenyl ether diamines and the pyromellitic acid anhydride of equimolar amount are added synthesizing polyamides acid solution in the dimethyl sulfoxide solvent, then add deionized water, sodium wolframate and strong phosphoric acid, be heated, stir, form solution, this solution casting on sheet glass, is lain against and carries out the ladder-elevating temperature imidization in the baking oven and namely obtain required phospho-wolframic acid-polyimide compound proton exchange membrane.
Concrete preparation method is:
(1) phenyl ether diamines and the pyromellitic acid anhydride of weighing equimolar amount add respectively in the dimethyl sulfoxide solvent, stirring at normal temperature 0.5-1h under nitrogen atmosphere, and synthetic weight concentration is the polyamic acid solution A of 8 %-12 %;
(2) the weight part proportioning by polyamic acid and sodium wolframate and strong phosphoric acid among the polyamic acid solution A is respectively 68-72 part, the ratio of 14-18 part and 18-10 part, weighing sodium wolframate and strong phosphoric acid, the solution A temperature is risen to 60 ℃-75 ℃, add successively sodium wolframate, strong phosphoric acid and water in solution A, the add-on of water is that the volume ratio of water and dimethyl sulfoxide (DMSO) is 1:10; Stirred 1-3 hour, and formed uniform solution B;
(3) oil bath of solution B vacuum is heated to 110 ℃-130 ℃, fully stirs, until moisture all evaporates in the solution, be down to room temperature, form uniform solution C;
(4) solution C is cast in lies against on the sheet glass in the loft drier, staged is heated to 280 ℃-300 ℃, is incubated 1 hour again, and cooling comes off, and gets phospho-wolframic acid-polyimide compound proton exchange membrane.
The amount weighing of the mass percent of the add-on of the dimethyl sulfoxide solvent polyamic acid solute that phenyl ether diamines and equimolar amount pyromellitic acid anhydride generate than reaction by metering in the polyamic acid solution A as 10%.
The mass percent concentration of strong phosphoric acid is 85.54%.
Solution C is cast in intensification heating, heat preserving mode after lying against in the loft drier on the sheet glass to be 120 ℃, 150 ℃, 200 ℃, 250 ℃ and 280 ℃-300 ℃ and to heat successively 12h, 1h, 1h, 1h and 1h.
Preparation method of the present invention is simple, owing in polyamic acid solution, adding sodium wolframate, strong phosphoric acid and water, wolframate radical generates phospho-wolframic acid with phosphate radical in sour environment, addition reaction occurs in the carboxyl on polyamic acid, phospho-wolframic acid and the phosphoric acid, carbonyl and hydroxyl each other, form stable network-like structure, the adding of water is conducive to dissolving and the reaction of inorganics, utilizes like this in-situ synthetic method to produce phospho-wolframic acid in film.The present invention is by the chemical reaction between polyamic acid, phosphoric acid and wolframate radical, last imidization has reached the purpose of the synthetic phospho-wolframic acid of original position on polyimide matrix, effectively avoided the problem of the poor easy phase-splitting of consistency between inorganic particulate and the polymkeric substance, made inorganic solid proton conductor can stablize, be scattered in the base material uniformly.Compare with Nafion, the proton exchange membrane of the present invention preparation at high temperature (below 100 ℃) proton conduction property obviously improves, and methanol permeability reduces, and swelling capacity reduces, and cost is low is convenient to carry out scale operation.
The present invention and current material compare with technology have advantages of as follows:
1, the compound proton exchange membrane proton conduction property at high temperature of the present invention's preparation is excellent, and its proton conduction speed is greater than the proton conductivity of Nafion film.
2, the compound proton exchange membrane of the present invention's preparation, the methanol permeability of 130-180 ℃ of temperature range is less than Nafion film, features good methanol diffusion resistance.
3, preparation technology of the present invention is simple, and the film cost is lower than the Nafion film, is easy to industrialization, can promote the development of high temperature direct methanol fuel cell.
Embodiment
Embodiment 1
1), 4.79 gram phenyl ether diamines and 5.21 gram pyromellitic acid anhydrides are dissolved in formation polyamic acid solution A in the 90g dimethyl sulfoxide (DMSO);
2), solution A stirs 1h in nitrogen atmosphere, be warming up to 65 ℃, adds 2.17g, mass percent concentration and be 85.54% strong phosphoric acid, 2.43g sodium wolframate and 8.18g water, stirs the uniform solution B of formation after 2 hours;
3), the oil bath of solution B vacuum is heated to 120 ℃, continue to stir until in the solution moisture all evaporate, cool to room temperature obtains homogeneous solution C;
4), solution C is cast on the sheet glass, lie against in the loft drier, heat successively 12h, 1h, 1h, 1h and 1h at 120 ℃, 150 ℃, 200 ℃, 250 ℃ and 300 ℃, after cooling comes off, namely obtain phospho-wolframic acid-polyimide compound proton exchange membrane.
During use this film was soaked in deionized water 12 hours, measure the methanol permeability of film with the barrier film method of diffusion.
Embodiment 2
1), 2.4 gram phenyl ether diamines and 2.6 gram pyromellitic acid anhydrides are dissolved in formation polyamic acid solution A in the 57.5g dimethyl sulfoxide (DMSO);
2), solution A is stirred 0.5h in nitrogen atmosphere, temperature rises to 60 ℃, adds 1.17g strong phosphoric acid, 1.14 g sodium wolframates and 5.23g water in solution A, stirs the uniform solution B of formation after 3 hours;
3), the oil bath of solution B vacuum is heated to 110 ℃, continue to stir until in the solution moisture all evaporate, cool to room temperature obtains homogeneous solution C;
4), solution C be cast on the sheet glass plate lie against in the loft drier, heat successively 12h, 1h, 1h, 1h and 1h at 120 ℃, 150 ℃, 200 ℃, 250 ℃ and 280 ℃, after cooling comes off, namely obtain phospho-wolframic acid-polyimide compound proton exchange membrane.
Embodiment 3
1), 6.23 gram phenyl ether diamines and 6.77 gram pyromellitic acid anhydrides are dissolved in formation polyamic acid solution A in the 131.44g dimethyl sulfoxide (DMSO);
2), solution A is stirred 1h in nitrogen atmosphere, temperature rises to 70 ℃, adds 3.26g strong phosphoric acid, 2.79 g sodium wolframates and 11.95g water in solution A, forms uniform solution B after stirring 1.5 hours under this temperature;
3), the oil bath of solution B vacuum is heated to 115 ℃, continue to stir until in the solution moisture all evaporate, cool to room temperature obtains homogeneous solution C;
4), solution C is cast on the sheet glass plate lies against in the loft drier, heat successively 12h, 1h, 1h, 1h and 1h at 120 ℃, 150 ℃, 200 ℃, 250 ℃ and 290 ℃, after cooling comes off, namely obtain required phospho-wolframic acid-polyimide compound proton exchange membrane.
Embodiment 4
1), 7.67 gram phenyl ether diamines and 8.33 gram pyromellitic acid anhydrides are dissolved in formation polyamic acid solution A in the 129.45g dimethyl sulfoxide (DMSO);
2), solution A is stirred 1h in nitrogen atmosphere, temperature rises to 65 ℃, adds 4.28g strong phosphoric acid, 3.2 g sodium wolframates and 11.77g water in solution A, stirs the uniform solution B of formation after 2 hours; 0.59 should change 0.8 into, otherwise ratio is not right.
3), the oil bath of solution B vacuum is heated to 125 ℃, continue to stir until in the solution moisture all evaporate, cool to room temperature obtains homogeneous solution C;
4), solution C is cast on the sheet glass plate lies against in the loft drier, heat successively 12h, 1h, 1h, 1h and 1h at 120 ℃, 150 ℃, 200 ℃, 250 ℃ and 300 ℃, after cooling comes off, namely obtain required phospho-wolframic acid-polyimide compound proton exchange membrane.
Embodiment 5
1), 9.58 gram phenyl ether diamines and 10.42 gram pyromellitic acid anhydrides are dissolved in formation polyamic acid solution A in the 146.67g dimethyl sulfoxide (DMSO);
2), solution A is stirred 1h in nitrogen atmosphere, temperature rises to 75 ℃, adds 5.68g strong phosphoric acid, 3.71 g sodium wolframates and 13.33g water in solution A, stirs the uniform solution B of formation after 3 hours;
3), the oil bath of solution B vacuum is heated to 130 ℃, continue to stir until in the solution moisture all evaporate, cool to room temperature obtains homogeneous solution C;
4), solution C is cast on the sheet glass plate lies against in the loft drier, heat successively 12h, 1h, 1h, 1h and 1h at 120 ℃, 150 ℃, 200 ℃, 250 ℃ and 300 ℃, after cooling comes off, namely obtain required phospho-wolframic acid-polyimide compound proton exchange membrane.
Comparative example
As a comparison, we utilize the phospho-wolframic acid of embodiment 1 preparation-polyimide compound proton exchange membrane and Nafion117 film, perviousness to its methyl alcohol compares, and two kinds of films were soaked in deionized water 12 hours, measures the methanol permeability of film with the barrier film method of diffusion.
The methanol permeability of table 1 phospho-wolframic acid/pi proton exchange membrane and the comparison of Nafion film
It should be noted that at last: obviously, above-described embodiment only is for example of the present invention clearly is described, and is not the restriction to embodiment.For those of ordinary skill in the field, can also make other changes in different forms on the basis of the above description.Here need not also can't give all embodiments exhaustive.And the apparent variation of being amplified out thus or change still are among protection scope of the present invention.