CN-121972030-A - Preparation method for CO by using interface spreading method2/N2Method for separating polymer films

Abstract

The invention aims to provide a method for preparing a polymer film for CO 2 /N 2 separation by using an interface spreading method, which belongs to the technical field of gas separation, the method is characterized in that a certain amount of methanol solution is doped into a polymer matrix (comprising polyimide, polyurethane and polysulfone), and a microphase structure is introduced under the action of interfacial surface tension and solvent polarity, so that the construction of a polymer film is realized. Compared with the traditional method, the method can effectively relieve the mutual restriction relation between the gas permeability and the selectivity of the polymer film. The membrane prepared by the method has the advantages of remarkably improved CO 2 permeability coefficient and CO 2 /N 2 separation selectivity, breaks through the limitation of the performance of conventional materials, and has wide application prospect.

Inventors

• LI JINPING
• WANG YONG
• JIA XIAOXIA
• WANG LI

Assignees

• 太原理工大学

Dates

Publication Date

20260505

Application Date

20260210

Claims (9)

1. 1. A method for preparing a polymer film for CO 2 /N 2 separation by using an interfacial spreading method is characterized by comprising the following steps: s1, drying a polymer matrix, and dissolving the dried polymer matrix in an organic solvent to obtain a polymer solution; S2, mixing the polymer solution with methanol to obtain a uniformly dispersed mixed solution; S3, after defoaming the mixed solution through ultrasonic treatment, dripping the mixed solution into a horizontal glass culture dish mold with distilled water added in advance, so that the mixed solution spreads on the water surface to form a polymer film; S4, supporting the formed polymer film by using a polyethersulfone substrate, and drying for 24-48 hours in a vacuum oven at 100-150 ℃ to remove the organic solvent, thereby obtaining the superblog homogeneous polymer film.
2. 2. The method for preparing a polymer film for CO 2 /N 2 separation by using the interfacial spreading method according to claim 1, wherein in S1, the polymer matrix comprises polyimide, polysulfone or polyurethane.
3. 3. A process for preparing a polymer film for CO 2 /N 2 separation by interfacial spreading according to claim 2 wherein the polyimide is synthesized from 10mmol of 4,4' - (hexafluoroisopropyl) phthalic anhydride and 10mmol of 2,4, 6-trimethyl-1, 3-phenylenediamine.
4. 4. The method for preparing a polymer film for CO 2 /N 2 separation by interfacial spreading according to claim 1, wherein in S1, the organic solvent comprises one of nitrogen methyl pyrrolidone, N, N-dimethylformamide and methylene chloride.
5. 5. The method for preparing a polymer film for CO 2 /N 2 separation by interfacial spreading according to claim 1, wherein in S1, the mass fraction of the polymer solution is 5-15wt%.
6. 6. The method for producing a polymer film for CO 2 /N 2 separation by interfacial spreading according to claim 1, wherein in S2, the mass of the polymer solution is 1g.
7. 7. A method for preparing a polymer film for CO 2 /N 2 separation by interfacial spreading according to claim 1 wherein the volume of methanol in S2 is 100-300. Mu.L.
8. 8. The method for preparing a polymer film for CO 2 /N 2 separation by using the interfacial spreading method according to claim 1, wherein in S2, the methanol is added in a small amount and multiple times.
9. 9. The method for preparing the polymer film for CO 2 /N 2 separation by using the interfacial spreading method according to claim 1, wherein in S2, the mixing mode is ultrasonic for 240-320min or magnetic stirring for 30min at a rotating speed of 900-1000 r/min.

Description

Method for preparing polymer film for CO 2/N2 separation by using interfacial spreading method Technical Field The invention belongs to the technical field of gas separation, and particularly relates to a method for preparing a polymer film for CO 2/N2 separation by using an interface spreading method. Background In recent years, with the increasing prominence of energy crisis and environmental problems, efficient and low-energy-consumption gas separation technology is becoming a research hotspot. Conventional gas separation processes such as cryogenic distillation and pressure swing adsorption, although widely used, have the problems of high energy consumption, complex equipment and high operation cost. In contrast, membrane separation technology has become a promising alternative in the fields of carbon dioxide capture and sequestration (CCS), natural gas purification, hydrogen energy purification, air separation, etc. because of its advantages such as low energy consumption, simple process, continuous operation, and environmental friendliness. Among the membrane materials, the high molecular polymer is the most widely used gas separation membrane material at present due to the abundant sources, excellent membrane forming property and strong chemical structure designability. The separation mechanism of the polymer gas separation membrane mainly follows a 'dissolution-diffusion model', namely gas molecules are dissolved in a membrane material first, and then the separation process is completed through molecular diffusion and pressure difference across the two sides of the membrane. The factors such as the flexibility of the polymer chain segment, the introduction of rigid groups, the distribution of polar groups, the microcosmic free volume structure and the like have decisive effects on the permeability and the selectivity of gas. Polyurethanes, polysulfones, and polyimides (e.g., 6 FDA-DAM) have found wide application in membrane separation technology in recent years as gas separation membrane materials. The polyurethane has excellent mechanical strength, thermal stability and adjustable permeability, and the 6FDA-DAM has excellent thermal stability and gas separation performance due to fluorine-containing groups. However, the conventional polymer membrane has the defect that permeability and selectivity are mutually restricted in CO 2/N2 separation, namely the selectivity is often reduced while the permeability of CO 2 is improved, so that the popularization of the conventional polymer membrane in industrial application is limited. In view of the above problems, researchers have attempted to improve film performance by structural design, doping modification, or compounding methods, but conventional film-making processes still have limitations in terms of film thickness uniformity, defect control, and permeation/selectivity optimization. Therefore, a novel membrane preparation method is urgently needed to remarkably improve the permeability coefficient of CO 2 and the selectivity of CO 2/N2 while guaranteeing the integrity and stability of the membrane. Disclosure of Invention Aiming at the defect that the permeability and the selectivity of a polymer gas separation membrane in the CO 2/N2 separation process are mutually restricted in the prior art, the invention provides a method for preparing a polymer film for CO 2/N2 separation by using an interface spreading method. The method can obviously improve the CO 2 permeability coefficient and the CO 2/N2 selectivity on the premise of ensuring the uniformity and the structural integrity of the membrane, thereby expanding the application potential of the method in the fields of gas separation and carbon capture. The invention adopts the following technical scheme: A method for preparing a polymer film for CO 2/N2 separation using an interfacial spreading method, comprising the steps of: s1, drying a polymer matrix, and dissolving the dried polymer matrix in an organic solvent to obtain a polymer solution; S2, mixing the polymer solution with methanol to obtain a uniformly dispersed mixed solution; S3, after defoaming the mixed solution through ultrasonic treatment, dripping the mixed solution into a horizontal glass culture dish mold with distilled water added in advance, so that the mixed solution spreads on the water surface to form a polymer film; S4, supporting the formed polymer film by using a polyethersulfone substrate, and drying for 24-48 hours in a vacuum oven at 100-150 ℃ to remove the organic solvent, thereby obtaining the superblog homogeneous polymer film. Further in S1, the polymer matrix comprises polyimide, polysulfone, or polyurethane. Further, the polyimide was synthesized from 10mmol of 4,4' - (hexafluoroisopropyl) phthalic anhydride and 10mmol of 2,4, 6-trimethyl-1, 3-phenylenediamine. Further, in S1, the organic solvent includes one of azomethyl pyrrolidone, N-dimethylformamide, and dichloromethane. Further, in S1, the mass fraction of