CN-121972020-A - Gas separation polymer composite membrane with high pressure resistance and preparation method and application thereof

Abstract

The invention relates to a gas separation polymer composite membrane with high pressure resistance, and a preparation method and application thereof. The crystallization type polymer is dissolved in a good solvent, then the polymer solution is uniformly coated on the surface of a flat substrate, and then the flat substrate is immersed in ionic liquid with weak interaction with the polymer, and solvent exchange treatment is carried out at constant temperature. The polymer/ionic liquid composite membrane prepared by the method is used for gas separation. The gas separation polymer composite membrane maintains high mechanical properties of the composite membrane while maintaining high ionic liquid content. The ionic liquid can stably exist in the polymer matrix, the continuity of a gas transmission passage is improved, meanwhile, the ionic liquid which is in weak interaction with a high molecular chain can effectively promote the polymer molecular chain to form a microcrystalline structure in the exchange process, the mechanical property of the composite membrane in the gas separation process is greatly improved, and the composite membrane has high pressure resistance, high permeability and high selectivity in the gas separation process. The invention has simple process, convenient operation and mild condition.

Inventors

• YANG JING
• DU YINGYING
• LI YONGJIN

Assignees

• 杭州师范大学

Dates

Publication Date

20260505

Application Date

20260212

Claims (10)

1. 1. A preparation method of a gas separation polymer composite membrane with high pressure resistance is characterized in that after a crystalline polymer is dissolved by a good solvent, an ionic liquid with weak interaction with the crystalline polymer is adopted to conduct solvent exchange, so that the interaction between the crystalline polymer and the crystalline polymer is superior to the interaction between the crystalline polymer and the solvent, the stacking induction crystallization of molecular chains of the crystalline polymer is promoted to form a large number of microcrystalline structures, meanwhile, a polymer chain segment of an amorphous region is denser, and finally, a solid polymer composite membrane is formed along with the construction of a polymer crystallization framework, and meanwhile, the interaction between the ionic liquid and the ionic liquid is enhanced, so that the ionic liquid is restrained in a tight space of the crystalline polymer crystallization framework and stably exists in a polymer matrix, and a continuous gas transmission channel is further formed.
2. 2. The method according to claim 1, characterized in that it comprises in particular the following steps: Dissolving a crystalline polymer in a good solvent to prepare a polymer solution with the mass fraction of 30-35 wt%; Uniformly coating a polymer solution on the surface of a flat substrate; immersing a flat substrate of a flat polymer solution into ionic liquid with weak interaction with the polymer, and carrying out solvent exchange treatment at constant temperature to obtain the polymer/ionic liquid composite membrane.
3. 3. The method of claim 2, wherein the crystalline polymer is one or more of polyvinylidene fluoride, poly (styrene-ethylene oxide-styrene), polyacrylonitrile, poly (vinylidene fluoride-hexafluoropropylene), polyvinylidene fluoride copolymer, polyethylene glycol-polystyrene, or poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene).
4. 4. The method of claim 1, wherein the good solvent is one or more of N, N-dimethylformamide, tetrahydrofuran, xylene, chloroform, ethyl acetate, N-dimethylacetamide.
5. 5. The method of claim 1, wherein the ionic liquid includes, but is not limited to, imidazole-based ionic liquids, pyridine-based ionic liquids, quaternary ammonium-based ionic liquids.
6. 6. The method of claim 1, wherein the solvent exchange treatment time is from 1h to 24 h.
7. 7. The method of claim 1, wherein the solvent exchange process temperature is 25 ℃.
8. 8. The method of claim 1, wherein the polymer solution has a mass fraction of 30 wt%.
9. 9. A gas separation polymer composite membrane having high pressure resistance, characterized by being produced by the method according to any one of claims 1 to 8.
10. 10. Use of the polymer composite membrane of claim 9 for gas separation.

Description

Gas separation polymer composite membrane with high pressure resistance and preparation method and application thereof Technical Field The invention belongs to the technical field of gas separation membranes, and particularly relates to a gas separation polymer composite membrane with high pressure resistance, and a preparation method and application thereof. Background At present, the large amount of carbon dioxide emissions cause a greenhouse effect, causing serious environmental problems. Carbon dioxide is also an important carbon resource, and the discharged carbon dioxide can be used for synthesizing organic compounds. Therefore, how to achieve efficient capturing and separating of carbon dioxide is one of the most urgent problems faced by sustainable development, and developing efficient carbon dioxide capturing materials is also an effective method for achieving "carbon peak, carbon neutralization". The carbon dioxide trapping method mainly comprises an absorption method, an adsorption method, a low-temperature distillation method and the like, and needs further optimization due to high energy consumption, high cost and low economic benefit. The membrane separation method is a novel separation technology which appears in recent decades, and is paid attention to because of the advantages of high energy efficiency, simple operation, low maintenance cost, environmental friendliness and the like. Among materials for separating gases by using a membrane, a polymer membrane is widely used because of the advantages of numerous sources of raw materials, low cost, good comprehensive performance and the like. Ionic liquids generally refer to organic salt materials that are liquid at room temperature and whose structure is generally composed of a bulk organic cation together with an organic or inorganic anion. The ionic liquid has strong dissolving capacity and extremely low vapor pressure, and is a common green liquid material for dissolving and absorbing carbon dioxide. Therefore, the ionic liquid and the polymer matrix are compounded to construct the composite membrane with high carbon dioxide permeability, high selectivity and excellent mechanical stability, and the efficient and stable carbon dioxide separation and recycling can be realized. The polymer/ionic liquid composite membrane has excellent processability, stable mechanical property and strong carbon dioxide solubility of ionic liquid of polymer materials, and is an ideal material in carbon dioxide separation and trapping technology. The composite membrane material has stronger physical and chemical interactions (such as Lewis acid-base interaction, hydrogen bond, van der Waals force and the like) between specific anions and cations (such as [ BMIM ] +、[Tf2N]-) of the ionic liquid and carbon dioxide, preferentially dissolves and transmits the carbon dioxide, and can form a permeation channel for carbon dioxide transmission. The polymer can effectively coat the ionic liquid, prevent the ionic liquid from losing under the high pressure difference operation condition, and meanwhile, the crystallization behavior of the polymer endows the material with strong chemical property. Regulating the microcrystalline structure of the polymer matrix and the continuous passage of carbon dioxide in the matrix are key to improving the mechanical properties of such composite membrane materials and the permeability and selectivity of carbon dioxide. The carbon dioxide channel construction in the composite membrane can be promoted by improving the carbon dioxide content in the composite membrane, so that the permeability and selectivity of carbon dioxide are improved. However, increasing the carbon dioxide content loses mechanical stability of the composite membrane, which in turn reduces the pressure resistance of the gas. Patent CN120623686a discloses a preparation method of tough polyvinyl alcohol-based ionic gel, the gel adopts twice solvent exchange, and realizes excellent performances of high toughness, high strength and the like of the gel by constructing a triple dynamic network structure comprising dynamic covalent bond, ionic bond and hydrogen bond. Patent CN120399271a discloses a preparation method of high-strength and high-toughness physical hydrogel, and the flocculated hydrogel is soaked in poor solvent for mechanical property regulation and control by solvent exchange, so as to prepare the novel gel material with high strength and high toughness. But the weak mechanical property and liquid leakage of the gel material greatly reduce the high pressure resistance and long-term running stability of the gel material. The invention utilizes a solvent exchange strategy to prepare the composite membrane with high pressure resistance and long-term operation stability, wherein the composite membrane has microcrystalline distribution and a polymer/ionic liquid bicontinuous phase structure. After the polymer is dissolved by the good solvent, the ionic liquid with w