阅读说明：本技术 一种通过表面交联制备高性能co2分离复合膜的方法 (Preparation of high-performance CO by surface crosslinking2Method for separating composite membrane ) 是由 王志 董松林 生梦龙 王纪孝 于 2020-06-11 设计创作，主要内容包括：本发明涉及一种通过表面交联制备高性能CO<Sub>2</Sub>分离复合膜的方法；在按照常规做法制得复合膜后,在分离层表面涂覆均苯三甲酰氯溶液,干燥后在分离层表面形成了一层交联层。均苯三甲酰氯溶液浓度在0.05wt％～0.2wt％。均苯三甲酰氯会与表面的氨基反应生成酰胺,形成交联结构,使膜表面变得更致密,提高了分离层的物理吸附选择性及扩散选择性。通过对均苯三甲酰氯浓度的调控,使分离层表面的交联度控制在合理的范围内,所制备的复合膜最终具备优异的CO<Sub>2</Sub>/N<Sub>2</Sub>选择性,交联后膜的CO<Sub>2</Sub>渗透速率在300GPU至1000GPU之间,CO<Sub>2</Sub>/N<Sub>2</Sub>分离因子在54至71之间。整个制膜过程简单,易于放大。(The invention relates to a method for preparing high-performance CO by surface cross-linking 2 A method of separating a composite membrane; after the composite membrane is prepared according to the conventional method, a trimesoyl chloride solution is coated on the surface of a separation layer, and a cross-linked layer is formed on the surface of the separation layer after drying. The concentration of the trimesoyl chloride solution is 0.05 wt% -0.2 wt%. Trimesoyl chloride reacts with amino on the surface to generate amide to form a cross-linked structure, so that the surface of the membrane becomes more compact, and the physical adsorption selectivity and the diffusion selectivity of the separation layer are improved. The concentration of trimesoyl chloride is regulated and controlled to divideThe crosslinking degree of the separation layer surface is controlled in a reasonable range, and the prepared composite membrane has excellent CO 2 /N 2 Selective, post-crosslinking CO of membranes 2 Permeation rate between 300GPU and 1000GPU, CO 2 /N 2 The separation factor is between 54 and 71. The whole film making process is simple and easy to amplify.)

1. A kind of expertPreparation of high-performance CO by over-surface crosslinking₂A method of separating a composite membrane; the method is characterized in that a trimesoyl chloride solution is coated on the surface of a separation layer, and a cross-linked layer is formed on the surface of the separation layer after drying.

2. The method according to claim 1, wherein the concentration of the trimesoyl chloride solution is 0.05 wt% to 0.2 wt%.

3. Preparation of high-performance CO by surface crosslinking₂A method of separating a composite membrane; the method is characterized by comprising the following steps:

(1) preparing a silicone rubber intermediate layer by adopting a wet coating method: completely dissolving silicon rubber in n-heptane to form a uniform silicon rubber solution, and adding tetraethyl orthosilicate cross-linking agent and dibutyltin dilaurate catalyst into the silicon rubber solution to form a uniform mixed solution; reacting the mixed solution at 20-35 ℃ to form an intermediate layer coating solution, and storing the intermediate layer coating solution in ice water bath to avoid gel; coating the middle layer membrane coating liquid on the surface of the polysulfone ultrafiltration membrane by scraping, and drying to obtain a middle layer;

(2) draw down of the separation layer: preparing a uniform solution from a separating layer material taking polyvinylamine as a main body, wherein the concentration of the solution is 0.05-2 wt%, and standing and defoaming to obtain a separating layer coating solution; coating the surface of the intermediate layer with the separating layer coating liquid in a scraping manner, and then drying the intermediate layer coating liquid to obtain a separating layer;

(3) carrying out surface crosslinking: the trimesoyl chloride solution with the concentration of 0.05 wt% -0.2 wt% is scraped on the surface of the separation layer and dried to prepare the surface cross-linked composite membrane.

4. The method as set forth in claim 3, wherein the concentration of the silicone rubber solution is 0.5 wt% to 2 wt%.

5. The method as set forth in claim 3, wherein the mass ratio of the silicone rubber, tetraethyl orthosilicate and dibutyltin dilaurate in the mixed solution is 5: 4: 4.

6. the method according to claim 3, wherein the mixed solution is reacted at 20 to 35 ℃ for 30 to 50 minutes.

Technical Field

The invention relates to a method for preparing high CO content by properly chemically crosslinking the surface of a separation membrane with polyvinylamine as a main material of a separation layer₂Selectivity and sufficient CO₂Permeation rate of CO₂A method for separating a composite membrane belongs to the field of preparation of gas separation membranes.

Background

CO₂The separation technology has wide application, such as carbon capture of flue gas and decarburization and purification of natural gas, hydrogen and methane. The technology has great effects on reducing greenhouse gas emission and improving the utilization rate of energy gas. The membrane technology is characterized in that the membrane technology is in CO due to the characteristics of environmental friendliness, easy operation, easy amplification and the like₂The field of separation is receiving increasing attention. Development of CO with high permeability and high selectivity₂Separation membranes have been the focus of research. The composite membrane is a good choice for preparing the high-permeability selective membrane due to the advantages of simple preparation method, easy amplification and the like. Composite membranes are typically composed of a support layer, an intermediate layer, and a separation layer. The support layer is usually an ultrafiltration membrane made of polysulfone, polyethersulfone, polyacrylonitrile and the like. The preparation of intermediate layers and separating layers is the focus of current research. The intermediate layer needs to have a high permeation rate so that the transfer resistance of the gas molecules in this portion is small. For the separation layer, its high permeability is generally required to ensure that the membrane material has a large free volume or a high degree of swelling during use, and a sufficiently thin thickness. While high selectivity usually requires optimization from three aspects of dissolution, diffusion and reaction.

There are generally three solutions to the problem of preparing membrane materials that combine high permeability and selectivity. Firstly, a brand new material is synthesized from a molecular structure and functional groups, and the method has high difficulty and is generally difficult to amplify. Secondly, the existing high-selectivity material is modified, so that the permeability coefficient of the material is improved, and the selectivity of the material is still high enough. Such as the mixed matrix membranes now of interest, by adding porous nanomaterials to dense polymer membranesTo increase its permeability coefficient. Thirdly, the existing high permeability coefficient membrane material is modified, so that the selectivity is improved, and the permeability coefficient is still high enough. For example, the selectivity of the polymer material with ultrahigh gas permeability coefficient such as inherent microporous polymer and thermal rearrangement polymer is improved by heat treatment, crosslinking and the like. The crosslinking is mainly divided into two modes of main body crosslinking and surface crosslinking according to the difference of crosslinking thickness. The crosslinking thickness of the membrane is larger due to the main body crosslinking mode, and the overall structure of the membrane is often too compact, so that the gas permeation rate of the membrane is lower, and the difficulty of industrial amplification is higher. Surface crosslinking may allow the membrane to have a thinner crosslinked layer, thereby reducing the adverse effect on gas permeation rate. For example, a polyimide film having a thickness of 50 μm is UV-crosslinked, and when the crosslinking thickness is 150nm, CO of the film₂Permeation rate was about 0.12GPU, CO₂/N₂A separation factor of about 21; CO of the film when the crosslinking thickness is 200nm₂Permeation rate was about 0.015GPU, CO₂/N₂The separation factor is about 26.

The composition of the separating layers varies from membrane to membrane, and the manner of cross-linking treatment employed varies. At present, two problems mainly exist in a separation layer taking PVAm as a main material: (1) to CO₂Has a low selectivity of, at 5atm, CO₂/N₂The separation factor of (2) is usually less than 45, and (2) the whole separation layer has a linear structure and is easily plasticized, so that the separation performance is attenuated.

Disclosure of Invention

The invention aims to improve the CO content of a composite membrane by chemically crosslinking the surface of a separation layer which takes polyvinylamine as a main material to a certain degree₂Selectivity while ensuring that the crosslinked composite membrane still has sufficiently high CO₂The permeation rate.

The conventional method for preparing the multilayer composite film with PVAm as a separation layer main body material at present comprises the following steps: firstly, coating a layer of silicon rubber on a polysulfone ultrafiltration membrane to prepare an intermediate layer, wherein the concentration of a silicon rubber solution is generally between 0.5 wt% and 2 wt%; then coating a separation layer solution taking PVAm as a main body material on the surface of the middle layer, wherein the concentration of the PVAm is generally between 0.05 wt% and 2 wt%, and drying to obtain the composite membrane.

The invention relates to a method for preparing high-performance CO by surface crosslinking₂A method of separating a composite membrane; after the composite membrane is prepared according to the conventional method, a trimesoyl chloride solution is coated on the surface of a separation layer, and a cross-linked layer is formed on the surface of the separation layer after drying. The concentration of the trimesoyl chloride solution is 0.05 wt% -0.2 wt%.

The invention is realized by the following technical scheme:

preparation of high-performance CO by surface crosslinking₂A method of separating a composite membrane; the method is characterized by comprising the following steps:

(1) preparing a silicone rubber intermediate layer by adopting a wet coating method: completely dissolving silicon rubber in n-heptane to form a uniform silicon rubber solution, and adding tetraethyl orthosilicate cross-linking agent and dibutyltin dilaurate catalyst into the silicon rubber solution to form a uniform mixed solution; reacting the mixed solution at 20-35 ℃ to form an intermediate layer coating solution, and storing the intermediate layer coating solution in ice water bath to avoid gel; coating the middle layer membrane coating liquid on the surface of the polysulfone ultrafiltration membrane by scraping, and drying to obtain a middle layer;

(2) draw down of the separation layer: preparing a uniform solution from a separating layer material taking polyvinylamine as a main body, wherein the concentration of the solution is 0.05-2 wt%, and standing and defoaming to obtain a separating layer coating solution; coating the surface of the intermediate layer with the separating layer coating liquid in a scraping manner, and then drying the intermediate layer coating liquid to obtain a separating layer;

(3) carrying out surface crosslinking: the trimesoyl chloride solution with the concentration of 0.05 wt% -0.2 wt% is scraped on the surface of the separation layer and dried to prepare the surface cross-linked composite membrane.

The concentration of the silicon rubber solution is 0.5 wt% -2 wt%.

The mass ratio of the silicon rubber, tetraethyl orthosilicate and dibutyltin dilaurate in the mixed solution is 5: 4: 4.

and reacting the mixed solution at the temperature of 20-35 ℃ for 30-50 minutes.

The invention utilizes the method to obtain high-performance CO₂Separation composite membrane, the main source thereofThe reason is as follows: firstly, trimesoyl chloride reacts with amino on the surface to generate amide to form a cross-linked structure, so that the surface of the membrane becomes more compact, and the physical adsorption selectivity and the diffusion selectivity of the separation layer are improved. Secondly, the degree of crosslinking on the surface of the separation layer can be controlled within a reasonable range by regulating and controlling the concentration of trimesoyl chloride, thereby weakening the CO crosslinking on the surface₂Diffusion rate and CO₂The negative effect of chemoselectivity. For the two reasons, the prepared composite membrane has excellent CO₂/N₂Selectivity while having sufficient CO₂The permeation rate.

The invention has the advantages that: the raw materials adopted in the preparation of the separation membrane have lower cost, the preparation process is simple, the surface crosslinking time is short, and the amplification is easy.

The invention develops a corresponding surface crosslinking technology aiming at a separation layer of which the main material is PVAm. The invention selects trimesoyl chloride as a chemical cross-linking agent. After the cross-linking agent solution contacts the surface of the separation layer, trimesoyl chloride reacts with primary amine groups on the surface layer of the membrane to form a cross-linked structure. The diffusion selectivity of the separation layer is enhanced through simple surface crosslinking, the original strong dissolution and reaction selectivity is combined, and finally the separation layer has CO pair₂The selectivity of the method is greatly improved. Meanwhile, a reticular cross-linked structure is formed on the surface, so that the plasticizing resistance of the separation layer is enhanced. Finally, since crosslinking only occurs at the surface layer, the crosslinked separation layer still has a relatively high CO content₂The permeation rate. Finally, CO of the film after crosslinking₂Permeation rate between 300GPU and 1000GPU, CO₂/N₂The separation factor is between 54 and 71. The whole film making process is simple and easy to amplify.

Drawings

FIG. 1 shows CO₂Scanning electron microscope image of the surface appearance of the separation composite membrane.

FIG. 2 shows CO₂And (3) a scanning electron microscope image of the section morphology of the separation composite membrane.

Detailed Description