Low-energy-consumption polyphenylene sulfide melt-blown non-woven proton exchange membrane as well as preparation method and application thereof

Abstract

The invention provides a preparation method and application of a low-energy-consumption polyphenylene sulfide (PPS) melt-blown non-woven proton exchange membrane, and belongs to the technical field of preparation of fuel cells and proton exchange membranes. A solid solvent (benzophenone, benzoin, stearic acid, polyvinyl alcohol, beeswax and the like) is introduced into polyphenylene sulfide melt-blowing, so that the processing temperature of polyphenylene sulfide melt-blowing is effectively reduced, and the coefficient of variation of a polyphenylene sulfide melt-blown non-woven fabric material is remarkably reduced; high-uniformity polyphenylene sulfide melt-blown non-woven fabric is used as a substrate supporting layer, proton exchange groups are obtained through sulfonation hydrophilic modification, then a nanofiller capable of promoting and accelerating proton conduction is uniformly dispersed into a proper sulfonated polymer membrane casting solution, and the functionalized modified polyphenylene sulfide melt-blown non-woven fabric is subjected to casting coating, so that the sulfonated polymer membrane is obtained. And finally hot-pressing and strengthening to form the film. The fiber diameter, the capillary flow aperture, the variable coefficient and the mechanical property of the functional modified polyphenylene sulfide melt-blown non-woven fabric can be adjusted by optimizing the doping content of the solid solvent. In addition, the proton conductivity, methanol permeability and other properties of the proton exchange membrane can be improved by optimizing the variety and doping amount of the nanofiller. The polyphenylene sulfide melt-blown non-woven proton exchange membrane disclosed by the invention is low in raw material price, simple in process, green and environment-friendly, and easy for large-scale low-cost production.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells and proton exchange membrane materials, and specifically relates to a low-energy-consumption polyphenylene sulfide melt-blown nonwoven fabric-based proton exchange membrane and a preparation method and application thereof. Background Art

[0002] Modern global development requires a lot of energy to meet all needs. However, the excessive use of petroleum energy has led to the depletion of non-renewable fossil fuel resources and the emission of numerous pollutants that are harmful to the environment, which has had a bad impact. Fuel cells are a high-efficiency, low-pollution, renewable energy conversion device. Its energy conversion efficiency can reach more than 50%, which is 2-3 times that of traditional heat engines. It is one of the most promising high-energy clean energy devices, and the proton exchange membrane (PEM), as the "heart" of the fuel cell, is one of the key core components. The proton exchange membrane not only has the function of separating reactants and providing channels for the migration and transmission of protons, but also has the function of blocking electrons. The performance of the proton exchange membrane directly affects the energy conversion efficiency and service life of the fuel cell.

[0003] At present, the most representative commercial proton exchange membrane, Nafion membrane, has shown good performance in applications. However, they have the disadvantages of high water absorption, high swelling rate, and poor alcohol resistance in fuel cells, which causes fuel loss. In addition, due to the limitation of their perfluorosulfonic acid structure, their preparation cost is expensive, and they have certain pollution to the environment, which is not conducive to large-scale production. Therefore, it is imperative to develop a new high-power PEM with lower methanol permeability, higher dimensional stability, more economical and environmentally friendly.

[0004] As a special engineering plastic with excellent comprehensive performance, polyphenylene sulfide (PPS) has better heat resistance, corrosion resistance, mechanical stability and dimensional stability than other aromatic polymers. These lay an innate foundation and advantage for reducing methanol permeability and swelling rate. In addition, polyphenylene sulfide (PPS) melt-blown non-woven fabrics and subsequent sulfonation modification processes have low processing costs, short production processes, high porosity and large specific surface area of ​​PPS melt-blown fibers, which are more conducive to the incorporation of some functional additives to further improve and enhance the various properties of composite PEM. Combining the above advantages, these excellent comprehensive properties are sufficient to prove that this is a promising ideal material to replace perfluorosulfonic acid (PFSA) membranes, with broad application prospects and exploration value. However, due to the excellent heat resistance of PPS, compared with other resins, the melt-blown temperature of PPS resin is higher, the requirements for process equipment and process parameter debugging are higher, and the melt-blown fiber scale is larger.

[0005] Therefore, developing an effective solution to the fuel loss caused by the high water absorption rate, high swelling rate and poor alcohol resistance of proton exchange membranes is an urgent technical problem to be solved. Summary of the invention

[0006] The present invention provides a preparation method and application of a low-energy polyphenylene sulfide melt-blown nonwoven fabric-based proton exchange membrane, the purpose of which is to effectively solve the problems of high water absorption, high swelling rate, poor alcohol barrier performance of the proton exchange membrane causing fuel loss and high preparation cost. The present invention explores and develops a new energy-saving and efficient PPS melt-blown process: solid solvents of different mass fractions are added as "plasticizers" for melt-blowing and mechanically premixed with PPS resin. Since the solid solvent has high volatility and low boiling point, it is easy to volatilize during the melt-blowing process, which increases the molecular distance of the polymer, reduces the force between the PPS molecules in the molten state, and then reduces the viscosity of the polymer in the molten state and increases the fluidity. Therefore, the melting temperature of the polymer is reduced, thereby reducing the processing temperature and improving the processing performance.

[0007] Nano-functionalized fillers are added, such as sulfonated graphene oxide, sulfonated zirconium phosphate, phosphotungstic acid, titanium dioxide, etc. These have greatly improved the various properties of the composite PEM to a certain extent. Therefore, considering the various advantages of the above-mentioned energy-saving and efficient PPS melt-blown process and the nano-functionalized fillers with hydrogen bond network proton sites, in the present invention, the present invention decides to combine the two to achieve a win-win situation.

[0008] The present invention adopts the following technical solution:

[0009] A method for preparing a low-energy polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane comprises the following steps:

[0010] (1) preparing polyphenylene sulfide melt-blown nonwoven fabric;

[0011] (2) adding a sulfonating agent to a sulfonating solvent to obtain a sulfonating reaction solution, and placing the polyphenylene sulfide melt-blown nonwoven fabric in the sulfonating reaction solution to obtain a sulfonated polyphenylene sulfide melt-blown nonwoven fabric;

[0012] (3) A sulfonating agent is added to a sulfonating solvent to obtain a sulfonating reaction solution, and an aromatic polymer resin is placed in the sulfonating reaction solution to carry out a sulfonating reaction to obtain a sulfonated polymer casting solution.

[0013] (4) dispersing the nanofiller into the sulfonated polymer casting solution to obtain a sulfonated polymer casting solution containing the nanofiller;

[0014] (5) Casting and coating the sulfonated polyphenylene sulfide melt-blown nonwoven fabric with the sulfonated polymer casting solution containing the nanofiller, and hot pressing to obtain a polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane.

[0015] Furthermore, the preparation process of the polyphenylene sulfide melt-blown nonwoven fabric in step (1) is to obtain the fabric by mechanically premixing benzophenone with different mass fractions and polyphenylene sulfide melt-blown grade resin.

[0016] Furthermore, the mass fraction of the benzophenone solid diluent does not exceed 16%.

[0017] Furthermore, the sulfonated solvent includes, but is not limited to, 1,2-dichloroethane, dichloromethane, and dimethyl sulfoxide.

[0018] Furthermore, the sulfonating agent is one or a mixture of two of concentrated sulfuric acid, chlorosulfonic acid, oleum, sulfuryl chloride, methanesulfonic acid, and sulfonyl chloride.

[0019] Furthermore, the sulfonation temperature in steps (2) and (3) is not less than 60°C.

[0020] Furthermore, the nanofiller in step (3) comprises one of a metal organic framework containing a proton group, a covalent organic framework, phosphotungstic acid, silicon dioxide or functionalized modified silicon dioxide, titanium dioxide, chitosan, amino acid, graphene or functionalized modified graphene.

[0021] Furthermore, the aromatic resin includes, but is not limited to, sulfonated polyethersulfone, sulfonated polysulfone, sulfonated polybenzimidazole, sulfonated polyetheretherketone, sulfonated polyetherketone, and sulfonated polyimide.

[0022] The functionalized modified polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane can be prepared by any of the above-mentioned preparation methods.

[0023] The functionalized modified polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane prepared by any of the above-mentioned preparation methods can be used in liquid flow batteries, fuel cells and hydrogen production by electrolysis of water.

[0024] (III) Beneficial effects

[0025] Compared with the prior art, the present invention provides a method for preparing a polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane with low energy consumption, which has the following beneficial effects:

[0026] 1. The present invention introduces solid solvents (benzophenone, benzoin, stearic acid, polyvinyl alcohol, beeswax, etc.) into polyphenylene sulfide melt-blown, which effectively reduces the processing temperature of polyphenylene sulfide melt-blown and significantly reduces the coefficient of variation of polyphenylene sulfide melt-blown nonwoven fabric materials;

[0027] Second, the fiber diameter, capillary flow pore size, coefficient of variation and mechanical properties of functionalized modified polyphenylene sulfide melt-blown nonwoven fabric can be adjusted by optimizing the solid solvent doping content.

[0028] 3. In addition, the proton conductivity and methanol permeability of the proton exchange membrane can be improved by optimizing the type and doping amount of nanofillers.

[0029] 4. During meltblowing, as the amount of DPK added increases, the processing temperature shows a significant downward trend, which prolongs the service life of the equipment and reduces safety hazards in production. This makes PPS consume less energy during the meltblowing process, and the reduction in processing temperature has certain theoretical guiding significance for the large-scale production of composite PEM based on PPS meltblown cloth.

[0030] 5. The maximum power density of the proton exchange membrane with the best performance in the present invention is 1.6 times that of the Nafion 117 membrane, and its alcohol resistance is 4 times higher than that of Nafion 117.

[0031] 6. The thermal decomposition temperature of the composite membrane of the present invention is close to 450°C, which is 100°C higher than the thermal decomposition temperature of Nafion 117.

[0032] 7. The low-energy functionalized modified polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane of the present invention has a simple preparation process, lower energy consumption, low raw material prices, and is easy to achieve low-cost industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a scanning electron microscope image of PPS melt-blown nonwoven fabric (ae are scanning electron microscope images of PPS melt-blown nonwoven fabric with a doping mass fraction of 0%, 4%, 8%, 12% and 16% of solid solvent respectively);

[0034] Figure 2 The sulfonation electron micrographs of the fiber membrane at different temperatures ((a), (b), (c), and (d) are the sulfonation electron micrographs of the fiber membrane at 50, 60, 70, and 80°C, respectively);

[0035] Figure 3 The XPS spectrum and FTIR spectrum of sulfur element in PPS fiber membrane before and after sulfonation;

[0036] Figure 4 Comparison of proton exchange membrane doped with a different mass fraction of MOF on a PPS melt-blown nonwoven fabric and commercial Nafion117 ((a) ion exchange capacity, (b) water contact angle, (c) proton conductivity, (d) proton conduction activation energy, (e) single cell performance and (f) durability). DETAILED DESCRIPTION

[0037] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] The present invention discloses a method for preparing a low-energy-consumption polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane, comprising the following steps:

[0039] (1) preparing polyphenylene sulfide melt-blown nonwoven fabric;

[0040] (2) adding a sulfonating agent to a sulfonating solvent to obtain a sulfonating reaction solution, and placing the polyphenylene sulfide melt-blown nonwoven fabric in the sulfonating reaction solution to obtain a sulfonated polyphenylene sulfide melt-blown nonwoven fabric;

[0041] (3) A sulfonating agent is added to a sulfonating solvent to obtain a sulfonating reaction solution, and an aromatic polymer resin is placed in the sulfonating reaction solution to carry out a sulfonating reaction to obtain a sulfonated polymer casting solution.

[0042] (4) dispersing the nanofiller into the sulfonated polymer casting solution to obtain a sulfonated polymer casting solution containing the nanofiller;

[0043] (5) Casting and coating the sulfonated polyphenylene sulfide melt-blown nonwoven fabric with the sulfonated polymer casting solution containing the nanofiller, and hot pressing to obtain a polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane.

[0044] According to the present invention, the mass fraction of the benzophenone solid diluent in step (1) does not exceed 16%.

[0045] Too high a content of benzophenone will easily affect the mechanical properties of polyphenylene sulfide melt-blown nonwovens.

[0046] According to the present invention, the sulfonated solvent in step (2) includes but is not limited to 1,2-dichloroethane, dichloromethane, dimethyl sulfoxide, etc.

[0047] According to the present invention, the sulfonating agent in step (2) is one or a mixture of two of concentrated sulfuric acid, chlorosulfonic acid, oleum, sulfuryl chloride, methanesulfonic acid, and sulfonyl chloride.

[0048] Preferably, 1,2-dichloroethane is used as the sulfonating solvent, and chlorosulfonic acid, concentrated sulfuric acid, or fuming sulfuric acid is selected as the sulfonating agent.

[0049] According to the present invention, the sulfonation temperature in step (2) is preferably 80° C. and the sulfonation time is more than 60 minutes.

[0050] Polyphenylene sulfide meltblown nonwoven fabric has excellent chemical stability. Sulfonation temperature and time below 60℃ / 60min will result in too low sulfonation degree.

[0051] According to the present invention, the nanofiller promoting proton conduction in step (3) includes one of a metal organic framework containing a proton group, a covalent organic framework, phosphotungstic acid, silicon dioxide or functionalized modified silicon dioxide, titanium dioxide, chitosan, amino acid, graphene or functionalized modified graphene.

[0052] According to the present invention, the sulfonated polymer casting solution in step (3) comprises a casting solution selected from the group consisting of sulfonated polyethersulfone, sulfonated polysulfone, sulfonated polybenzimidazole, sulfonated polyetheretherketone, sulfonated polyetherketone, and sulfonated polyimide.

[0053] The sulfonated aromatic polymer resin is dissolved in certain organic solvents to form a casting liquid, which is evenly cast and coated on the functionalized modified polyphenylene sulfide melt-blown nonwoven fabric. This not only greatly improves the mechanical stability of the prepared composite proton exchange membrane, but also greatly reduces the methanol permeability and improves the proton conductivity.

[0054] The present invention will be further described below with reference to the embodiments.

[0055] Example 1

[0056] 1) After mechanically premixing 4% by mass of benzophenone with polyphenylene sulfide melt-blown grade resin, the polyphenylene sulfide melt-blown nonwoven fabric was produced by adjusting the process parameters of the melt-blown machine (the nozzle temperature was adjusted to 275° C.);

[0057] 2) In a three-necked flask containing 50 ml of 1,2-dichloroethane, add 200 μl of chlorosulfonic acid, mix and stir evenly, add 0.3 g of polyphenylene sulfide melt-blown nonwoven fiber cloth, and carry out sulfonation modification under nitrogen atmosphere at 80°C / 90 min, and finally wash with acetone and dry;

[0058] 3) dissolving a sulfonated polysulfone resin having a sulfonation degree of 60% in an organic solvent of N,N-dimethylformamide (DMF) to form a casting solution, and then adding 1% by mass of a Co-tri metal organic framework nanofiller to the casting solution, stirring and dispersing the mixture uniformly;

[0059] 4) The casting solution containing Co-tri was uniformly cast and coated on the sulfonated modified polyphenylene sulfide melt-blown nonwoven fiber cloth, and after drying, a proton exchange membrane was obtained by hot pressing at 80°C / 10MPa using a hot press. The proton conductivity of the membrane was 0.183Scm -1 , methanol permeability is 4.78×10 -7 cm 2 s -1 , selectivity is 16.32×104 S s cm -3 , ion exchange capacity is 1.2meq g -1 , swelling rate is 11.11%, and water absorption rate is 32.3%.

[0060] Example 2

[0061] 1) After mechanically premixing benzoin with a mass fraction of 8% with a polyphenylene sulfide melt-blown grade resin, a polyphenylene sulfide melt-blown nonwoven fabric was produced by adjusting the process parameters of the melt-blown machine (the nozzle temperature was adjusted to 267° C.);

[0062] 2) In a three-necked flask containing 50 ml of 1,2-dichloroethane, add 30 ml of concentrated sulfuric acid, mix and stir evenly, add 0.5 g of polyphenylene sulfide melt-blown nonwoven fiber cloth, carry out sulfonation modification under nitrogen atmosphere at 70°C / 90 min, and finally wash and dry in an ice water bath;

[0063] 3) dissolving a sulfonated polyetheretherketone resin having a sulfonation degree of 60% in an organic solvent of N,N-dimethylformamide (DMF) to form a casting solution, and then adding 12% by mass of a lysine (amino acid) nanofiller to the casting solution, stirring and dispersing the mixture uniformly;

[0064] 4) The casting solution containing lysine is uniformly cast and coated on the sulfonated modified polyphenylene sulfide melt-blown nonwoven fiber cloth, and after drying, a proton exchange membrane is obtained by hot pressing at 80°C / 10MPa using a hot press. The proton conductivity of the membrane is 0.313Scm -1 , methanol permeability is 6.32×10 -7 cm 2 s -1 , selectivity is 18.67×10 4 S s cm -3 , ion exchange capacity is 1.45meq g -1 , swelling rate is 12.31%, and water absorption rate is 38.27%.

[0065] Example 3

[0066] 1) After mechanically premixing 12% of stearic acid with a polyphenylene sulfide melt-blown grade resin, a polyphenylene sulfide melt-blown nonwoven fabric was produced by adjusting the process parameters of the melt-blown machine (the nozzle temperature was adjusted to 262° C.);

[0067] 2) In a three-necked flask containing 100 ml of dichloromethane, add 20 ml of fuming sulfuric acid, mix and stir evenly, add 0.5 g of polyphenylene sulfide melt-blown nonwoven fiber cloth, carry out sulfonation modification under nitrogen atmosphere at 60°C / 90 min, and finally wash and dry in an ice water bath;

[0068] 3) dissolving a sulfonated polybenzimidazole resin having a sulfonation degree of 45% in an organic solvent of N,N-dimethylformamide (DMF) to form a casting solution, and then adding 6% by mass of a phosphotungstic acid nanofiller to the casting solution, stirring and dispersing the mixture uniformly;

[0069] 4) The casting solution containing phosphotungstic acid is uniformly cast and coated on the sulfonated modified polyphenylene sulfide melt-blown nonwoven fiber cloth, and after drying, a proton exchange membrane is obtained by hot pressing at 80°C / 10MPa using a hot press. The proton conductivity of the membrane is 0.192Scm -1 , methanol permeability is 8.71×10 -7 cm 2 s -1 , selectivity is 14.87×104S s cm -3 , ion exchange capacity is 1.67meq g -1 , swelling rate is 10.43%, and water absorption rate is 42.15%.

[0070] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a low-energy polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane, characterized in that: The steps include: (1) preparing polyphenylene sulfide melt-blown nonwoven fabric; (2) adding a sulfonating agent to a sulfonating solvent to obtain a sulfonating reaction liquid, and placing the polyphenylene sulfide melt-blown nonwoven fabric in the sulfonating reaction liquid to obtain a sulfonated polyphenylene sulfide melt-blown nonwoven fabric; (3) A sulfonating agent is added to a sulfonating solvent to obtain a sulfonating reaction solution, and an aromatic polymer resin is placed in the sulfonating reaction solution to carry out a sulfonating reaction to obtain a sulfonated polymer casting solution. (4) dispersing the nanofiller into the sulfonated polymer casting solution to obtain a sulfonated polymer casting solution containing the nanofiller; (5) Casting and coating the sulfonated polyphenylene sulfide melt-blown nonwoven fabric with the sulfonated polymer casting solution containing the nanofiller, and hot pressing to obtain a polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane.

2. The preparation method according to claim 1, characterized in that: The preparation process of the polyphenylene sulfide melt-blown nonwoven fabric in step (1) is to obtain the fabric by mechanically premixing benzophenone with different mass fractions and polyphenylene sulfide melt-blown grade resin.

3. The preparation method according to claim 2, characterized in that: The mass fraction of the benzophenone solid diluent does not exceed 16%.

4. The preparation method according to claim 1, characterized in that: The sulfonated solvent includes, but is not limited to, 1,2-dichloroethane, dichloromethane, and dimethyl sulfoxide.

5. The preparation method according to claim 1, characterized in that: The sulfonating agent is one or a mixture of two of concentrated sulfuric acid, chlorosulfonic acid, fuming sulfuric acid, sulfuryl chloride, methanesulfonic acid, and sulfonyl chloride.

6. The preparation method according to claim 1, characterized in that: The sulfonation temperature in the steps (2) and (3) is not less than 60°C.

7. The preparation method according to claim 1, characterized in that: The nanofiller in step (3) includes one of a metal organic framework containing a proton group, a covalent organic framework, phosphotungstic acid, silicon dioxide or functionalized modified silicon dioxide, titanium dioxide, chitosan, amino acid, graphene or functionalized modified graphene.

8. The preparation method according to claim 1, characterized in that: The aromatic resin includes, but is not limited to, sulfonated polyethersulfone, sulfonated polysulfone, sulfonated polybenzimidazole, sulfonated polyetheretherketone, sulfonated polyetherketone, and sulfonated polyimide.

9. A modified polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane, characterized in that: The invention comprises a functionalized modified polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane prepared by the preparation method described in any one of claims 1 to 8.

10. An application of a modified polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane, characterized in that: The invention comprises the use of a functionalized modified polyphenylene sulfide melt-blown nonwoven fabric-based ion exchange membrane prepared by the preparation method described in any one of claims 1 to 8 in liquid flow batteries, fuel cells and hydrogen production by electrolysis of water.

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