CN-122006509-A - Hollow fiber composite membrane and preparation method thereof

Abstract

The invention discloses a hollow fiber composite membrane and a preparation method thereof, wherein the method comprises the following steps of wetting a hollow fiber membrane substrate by using a pre-wetting liquid, so that the pre-wetting liquid occupies a pore channel structure of the hollow fiber membrane substrate; the method comprises the steps of forming an intermediate layer, namely pouring an intermediate layer casting solution on the inner surface of the hollow fiber membrane substrate after prewetting, blowing to form an intermediate layer casting film liquid film, solidifying the intermediate layer casting film liquid film to form an intermediate layer, forming a selective layer casting film liquid film after blowing by pouring the selective layer casting solution on the inner surface of the intermediate layer, solidifying the selective layer casting film liquid film, and forming a selective layer on the inner surface of the hollow fiber membrane substrate.

Inventors

• HOU WEN
• YIN DENGGUO
• DU WENTAO
• ZHUANG YUANFA
• DAI ZHONGDE

Assignees

• 东方电气集团东方锅炉股份有限公司
• 四川大学

Dates

Publication Date

20260512

Application Date

20260120

Claims (10)

1. 1. The preparation method of the hollow fiber composite membrane is characterized by comprising the following steps: A pre-wetting step of wetting a hollow fiber membrane substrate by using a pre-wetting liquid, so that the pre-wetting liquid occupies a pore channel structure of the hollow fiber membrane substrate; The method comprises the steps of forming an intermediate layer, namely pouring an intermediate layer casting solution on the inner surface of the hollow fiber membrane substrate after prewetting, and blowing to form an intermediate layer casting film liquid film; and forming a selective layer, namely pouring the selective layer casting film liquid on the inner surface of the middle layer, blowing and forming a selective layer casting film liquid film, and solidifying the selective layer casting film liquid film to form a selective layer on the inner surface of the hollow fiber membrane substrate.
2. 2. The method according to claim 1, wherein the pre-wetting liquid is a solution which does not dissolve or swell the hollow fiber membrane substrate and does not react with the selective layer casting liquid.
3. 3. The method of claim 2, wherein the pre-wetting fluid is an organic solution having a relatively low surface energy.
4. 4. A method of preparation according to claim 3 wherein the material of the intermediate layer is a polymer which is easily spread uniformly and has a high gas permeability coefficient.
5. 5. A method of preparation according to claim 3 wherein the material of the intermediate layer is polydimethylsiloxane.
6. 6. The method according to claim 4, wherein the concentration of the intermediate layer casting solution is 2 to 10wt.%, and/or the time for pouring the intermediate layer casting solution is 1 to 3 minutes, and/or the time for purging the intermediate layer casting solution is 30 to 60 seconds.
7. 7. The method of claim 1, wherein the material of the selective layer is a polymer selective for CO 2 .
8. 8. The method according to claim 1 or 7, wherein the concentration of the selective layer casting solution is 0.1 to 2wt.%, and/or the time of casting the selective layer casting solution is 1 to 3 minutes, and/or the time of purging the selective layer casting solution is 30 to 60 seconds.
9. 9. The method according to claim 1, wherein the curing step is performed by heating or blowing, the curing temperature is 40 ℃ to 60 ℃, the curing time is 20 hours to 30 hours, and/or the number of applications of the selective layer is at least one.
10. 10. A hollow fiber composite membrane produced by the production method according to any one of claims 1 to 9, the structure of the hollow fiber composite membrane comprising a hollow fiber membrane substrate, an intermediate layer on the inner surface thereof, and a selective layer on the inner surface of the intermediate layer.

Description

Hollow fiber composite membrane and preparation method thereof Technical Field The invention relates to the technical field of gas separation, in particular to a hollow fiber composite membrane and a preparation method thereof. Background The gas separation membrane technology plays an important role in the field of CO 2 separation as a high-efficiency and energy-saving separation technology. Compared with the traditional separation method such as cryogenic separation, distillation, absorption and the like, the membrane separation technology has the advantages of simple process, environmental friendliness, small occupied space, high separation efficiency and the like. Hollow fiber membranes have advantages such as high packing density and small occupied area compared with flat membranes, and have been receiving attention from researchers. The conventional hollow fiber membrane is mainly applied to water treatment. The porous membrane has larger pore diameter, can provide a low resistance channel for gas mass transfer when being applied to gas separation, does not have a size sieving effect, and has the characteristics of high permeability and low selectivity, such as a commercial Polysulfone (PSF) membrane, a polyether sulfone (PES) membrane and the like, wherein the CO 2 permeability coefficient of the porous membrane is often more than 1X 10 6 GPU, but the porous membrane has basically no selectivity of CO 2 and other gases (such as N 2、CH4). The hollow fiber membrane special for gas separation realizes size screening through smaller pore diameter, but has larger mass transfer resistance and shows the characteristics of high selectivity and low permeability. For example, chinese patent CN116943460A discloses a method for preparing an inner surface compact hollow fiber membrane for gas separation, which is characterized in that an inner surface solvent is used for fast solidificationThe hollow fiber membrane with compact inner surface is prepared by a way of inducing a loose structure by a coagulating bath, and the CO 2/CH4 selectivity as high as 40 can be realized, but the CO 2 permeability coefficient is less than 50GPU. In order to overcome the limitation of Trade-off effect between permeability and selectivity in homogeneous hollow fiber membranes prepared from a single material, researchers use ultrafiltration membranes with larger pore diameters as base membranes, and coat the specific selective layer with CO 2 on the outer surface of the base membranes to prepare the multilayer composite membrane. For example, chinese patent CN107126847B uses commercial hollow fiber membrane as substrate membrane, and uses Polydimethylsiloxane (PDMS) functional layer to coat and then initiates graft polymerization on the surface to prepare the high-performance hollow fiber organic gas separation membrane. Because hollow fiber membranes are of a thin and long integral structure, the inner diameter of the hollow fiber membranes is generally 0.8-1.0mm, the outer diameter of the hollow fiber membranes is generally 1.3-1.5mm, and the length of the hollow fiber membranes is often greater than 1m, so that the uniform coating of the membrane casting solution of a selection layer on the inner surface is extremely difficult, and the direct dip coating method is simpler to operate when the selection layer is coated on the outer surface of a membrane wire, and is a method commonly adopted in the patents disclosed and reported at present. However, in the subsequent membrane wire transportation, filling and actual gas separation processes, fluctuation of working conditions easily causes mutual friction of outer surface layers of the membrane wires, so that abrasion of a selection layer is caused, and the gas separation performance of the hollow fiber membrane is affected. Disclosure of Invention In view of the above, the present invention aims to provide a hollow fiber composite membrane and a preparation method thereof, which aims to overcome the technical problem of gas separation efficiency reduction caused by selective layer abrasion. In order to achieve the above purpose, the present invention adopts the following technical scheme: in a first aspect, the present application provides a method for preparing a hollow fiber composite membrane, comprising the steps of: A pre-wetting step of wetting a hollow fiber membrane substrate by using a pre-wetting liquid, so that the pre-wetting liquid occupies a pore channel structure of the hollow fiber membrane substrate; The method comprises the steps of forming an intermediate layer, namely pouring an intermediate layer casting solution on the inner surface of the hollow fiber membrane substrate after prewetting, and blowing to form an intermediate layer casting film liquid film; and forming a selective layer, namely pouring the selective layer casting film liquid on the inner surface of the middle layer, blowing and forming a selective layer casting film liquid film, and solidifying