CN110898628A

CN110898628A - Preparation method of polyvinyl amine with hydrolysis degree of 40-70% for preparing carbon dioxide separation composite membrane

Info

Publication number: CN110898628A
Application number: CN201911064749.1A
Authority: CN
Inventors: 王志; 原野; 邢广宇; 许瑞; 生梦龙; 董松林; 王纪孝
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2019-11-04
Filing date: 2019-11-04
Publication date: 2020-03-24

Abstract

The invention relates to a preparation method of polyvinylamine with hydrolysis degree of 40-70% for preparing a carbon dioxide separation composite membrane, which comprises the steps of preparing poly-N-vinylformamide (PNVF) into a solution, and then adding hydrochloric acid into the solutionThe concentration of hydrochloric acid in the reaction solution is 8-12 wt%; stirring and stirring in N₂Hydrolyzing at constant temperature of 65-75 ℃ under protection to obtain PVAmHCl; adding PVAm & HCl solution into excessive ethanol to precipitate to obtain white PVAm & HCl solid; dissolving the obtained PVAmHCl solid in deionized water; and adding excessive anion exchange resin into the solution, stirring until the pH of the solution is 12.0-13.0, and performing suction filtration to obtain a PVAm aqueous solution with the hydrolysis degree of 40-70%. Blade coating is carried out on the surface of the ultrafiltration membrane to obtain CO₂Separating the membrane. The prepared films all have good CO₂Permeation rate and separation factor. Has a strong application prospect.

Description

Preparation method of polyvinyl amine with hydrolysis degree of 40-70% for preparing carbon dioxide separation composite membrane

Technical Field

The invention belongs to the field of preparation of gas separation membrane materials; relates to a method for synthesizing polyvinylamine with hydrolysis degree of 40-70% to prepare a high-performance carbon dioxide separation composite membrane; by comprehensively regulating and controlling the groups and optimizing the preparation process of the key material of the separation membrane, the key material polyvinyl amine with the hydrolysis degree of 40-70% is obtained. In particular to a polyvinyl amine separation membrane with excellent carbon dioxide permeation selectivity and hydrolysis degree of 40-70%.

Background

With the development of global economy, environmental problems and energy problems have become a problem that needs to be solved urgently in the development of economy. The combustion of traditional fossil energy such as coal, petroleum and the like brings about a serious environmental pollution problem. CO 2₂The large amount of emission causes global greenhouse effect, leads to global temperature rise, damages the ecosystem and seriously threatens the survival of the earth life. Thus, CO₂Emission reduction becomes a major global topic^[1]. Common CO at present₂Separation techniques include cryogenic separation, adsorption, absorption, and membrane separation. The membrane separation method has the advantages of less fixed investment, simple operation, low energy consumption, small occupied area and the like, and CO is obtained₂Has good development prospect in the separation field^[2]. Is currently in useThe polymer membrane for gas separation has the advantages of good mechanical stability, easy amplification, low cost and easy availability, and has received extensive attention from researchers^[3]。

CO₂The separation mechanism of the separation membrane comprises molecular sieving, diffusion selection, dissolution selection, reaction selection or the combined action of multiple mechanisms^[3]. Among them, the reaction selective membrane, also called a facilitated transport membrane, is a membrane having high permselectivity. Such separation membranes should be rich in para-CO₂Carrier with higher adsorption selectivity (such as pyridyl, amido, carboxylate and other basic groups)^[4]CO can be achieved by a reversible chemical reaction between the component to be separated and the support₂High permeation rate and high selectivity separation. At the same time, the separation membrane should also have loose, flexible and low crystalline polymer chains. In addition, the reaction selection membrane should also immobilize the carrier in the membrane under the action of electrostatic force or covalent bond, etc.

Polyvinyl amine (PVAm) is a polymer with CO₂The high molecular polymer for promoting the transfer function is a reaction selection membrane material with excellent performance. The polymer contains a large number of amino groups, and can react with CO in the presence of water molecules₂The molecules are subjected to reversible reaction, and the prepared membrane has higher permeability selectivity^[5]. Currently, commercial PVAm is used primarily to enhance paper strength, aid drainage, retention and hold-up effects, and to clarify liquids as flocculants. The PVAm is mainly prepared by an alkaline hydrolysis method, the hydrolysis degree of the PVAm is very high, and a large number of amino groups exist in a molecular chain segment, so that the hydrogen bonding force of the PVAm chain segment is too strong, and the crystallinity is very high. PVAm prepared by the method is used as CO₂The separation membrane material has poor film forming property and low permselectivity, and limits the membrane material to CO₂Application in the field of separation membranes.

Experimental research shows that compared with alkaline hydrolysis, the acidic hydrolysis of the preliminarily polymerized poly-N-vinylformamide (PNVF) can obtain the controllable PVAm with lower hydrolysis degree^[6]. However, in order to obtain a catalyst having a higher CO content₂The degree of hydrolysis of the PVAm, a membrane material with permselective properties, needs to be further controlled. The main reasons are as follows: PV with low degree of hydrolysisAm contains a small amount of effective carriers, the membrane has weak transfer promotion performance and poor gas permeation selectivity. And PVAm with high hydrolysis degree has too many amino groups, the acting force of hydrogen bonds among the groups is strong, the crystallinity is greatly improved, so that too many crystallization areas in the membrane are caused, and the permeability of gas in the membrane is reduced. At the same time, the promotion of gas transmission in the membrane is also weakened due to the reduction of the number of effective carriers caused by crystallization, resulting in the reduction of the separation performance of the membrane^[7]. In addition, in the high-temperature hydrolysis process, as the reaction time increases, the molecular segments of PVAm are easily broken, and the molecular weight of PVAm having a high degree of hydrolysis decreases, affecting the film-forming performance. Experiments show that PVAm with the hydrolysis degree of 40-70% has a proper amount of functional groups, higher molecular weight and lower crystallinity, and the prepared CO has₂The separation composite membrane has high selectivity and high permeability.

Therefore, the synthesized polyvinylamine with hydrolysis degree of 40-70% is used for preparing high-performance CO₂Separation composite membranes are a key issue that currently needs to be studied.

Reference to the literature

[1]Georgia, intensified CO at high pressure₂Study of permselectivity of separation membranes [ D]Tianjin, Tianjin university, 2015.

[2]Qiao Z,Zhao S,Sheng M,et al.Metal-induced ordered microporouspolymers for fabricating large-area gas separation membranes[J].NatureMaterials,2019,18(2):163-168.

[3]On the grounds of CO₂Isolated high Performance Polyvinylamine Membrane development [ D]Tianjin, Tianjin university, 2019.

[4]Li S,Wang Z,Yu X,et al.High-performance membranes with multi-permselectivity for CO₂separation[J].Advanced Materials,2012,24(24):3196-3200.

[5]Wang M,Wang Z,Li S,et al.Ahigh performance antioxidative and acidresistant membrane prepared by interfacial polymerization for CO₂separationfrom flue gas[J].Energy&Environmental Science,2013,6(2):539-551.

[6]Qiao Z,Wang Z,Yuan S,et al.Preparation and characterization ofsmall molecular amine modified PVAm membranes for CO₂/H₂separation[J].Journalof Membrane Science,2015,475:290-302.

[7]Yuan S,Wang Z,Qiao Z,et al.Improvement of CO₂/N₂separationcharacteristics of polyvinylamine by modifying with ethylenediamine[J].Journal of Membrane Science,2011,378(1-2,SI):425-437.

[8]Preparation of Ichhai amino-containing fixed carrier membrane and CO thereof₂Transfer characteristics study [ D]Tianjin, Tianjin university, 2007.

Disclosure of Invention

The hydrolysis degree of PVAm can be improved by increasing the concentration of hydrochloric acid in the solution during hydrolysis, the hydrolysis time and the hydrolysis temperature, the hydrolysis reaction tends to be balanced with the increase of the hydrolysis time, and the excessive hydrolysis temperature can cause the aging yellowing of the polymer, thereby losing CO₂Separation capacity. Therefore, the hydrolysis degree of the PVAm can be effectively controlled by regulating and controlling the concentration of hydrochloric acid in the solution, the hydrolysis time and the hydrolysis temperature.

The method obtains the PVAm with the hydrolysis degree of 40-70% by regulating and controlling the concentration of hydrochloric acid in the solution, the hydrolysis time and the hydrolysis temperature. The material is used as a separating layer material and is coated on an ultrafiltration membrane in a scraping way to prepare high-performance CO₂Separating the composite membrane. For the prepared CO₂Separating the composite membrane to obtain mixed gas (CO)₂/N₂15/85、CO₂/H₂40/60、CO₂/CH₄10/90) was tested. The results show that the membranes produced all have good CO₂Permeation rate and separation factor. CO prepared from PVAm with hydrolysis degree of 40-70%₂Separating CO from composite membranes₂The permeation rate and separation factor are higher. The preparation process can be used for scale-up production, and is suitable for preparing CO in batches₂Separation of the composite membrane the separation layer provides the starting material. The experimental conditions of the invention are easy to control, the obtained PVAm has excellent film forming property, and the prepared gas separation membrane has excellent permeability selection performance and high repeatability.

The technical scheme of the invention is as follows:

the preparation method of the polyvinyl amine with the hydrolysis degree of 40-70% for preparing the carbon dioxide separation composite membrane comprises the following steps:

1) preparing poly N-vinylformamide (PNVF) into a solution, and then adding hydrochloric acid into the solution until the concentration of the hydrochloric acid in the reaction solution is 8-12 wt%; stirring and stirring in N₂Hydrolyzing at constant temperature of 65-75 ℃ under protection to obtain polyvinyl amine hydrochloride (PVAm & HCl);

2) adding PVAm & HCl solution into excessive ethanol to precipitate to obtain white PVAm & HCl solid;

3) dissolving the obtained PVAmHCl solid in deionized water; and adding excessive anion exchange resin into the solution, stirring until the pH of the solution is 12.0-13.0, and performing suction filtration to obtain a PVAm aqueous solution with the hydrolysis degree of 40-70%.

The concentration of the poly-N-vinylformamide solution in the step 1) is 9.5-10.5 wt%.

In said step 1) at N₂Hydrolyzing for 4-5 h at the constant temperature of 65-75 ℃ under protection.

And 3) dissolving the PVAm & HCl solid in the deionized water, and preparing into 1-3 wt% aqueous solution.

The anion exchange resin includes but is not limited to styrene type anion exchange resin or polyethylene type pyridine resin.

The method for preparing the carbon dioxide separation composite membrane by using 40-70% of polyvinyl amine prepared by the method of the invention is characterized in that PVAm aqueous solution with the hydrolysis degree of 40-70% is blade-coated on the surface of an ultrafiltration membrane to obtain CO₂Separating the composite membrane.

The ultrafiltration membrane comprises materials such as but not limited to a polysulfone ultrafiltration membrane, a polyacrylonitrile ultrafiltration membrane, a polyether sulfone ultrafiltration membrane, a polyether ether ketone ultrafiltration membrane, a polyvinylidene fluoride ultrafiltration membrane or a polycarbonate ultrafiltration membrane.

The basic structural equation of the invention is as follows:

due to the fact that PVAm has extremely strong water absorption capacity, when organic element content is tested, data errors of H elements and O elements are large, and therefore the hydrolysis degree is calculated by using the content of C elements and the content of N elements; the mole fraction of the hydrolyzed repeat units is x, the formula of the PVAm obtained by the reaction is as follows:

this makes it possible to obtain:

in this way,

wherein x is the degree of hydrolysis of PVAm as referred to herein.

For the prepared CO₂Separating the composite membrane to obtain mixed gas (CO)₂/N₂15/85、CO₂/H₂40/60、CO₂/CH₄10/90) was tested. The results show that the film made of PVAm with hydrolysis degree of 40-70% has the highest CO₂Separation permeability and selectivity. For CO₂/N₂System, separation membrane CO₂The highest penetration rate can reach 726.3GPU, and the highest separation factor can reach 70.60; for CO₂/H₂System, separation membrane CO₂The highest penetration rate can reach 469.3GPU, and the highest separation factor can reach 29.12; for CO₂/CH₄System, separation membrane CO₂The highest permeation rate can reach 571.1GPU, and the highest separation factor can reach 42.87. Table 1 lists several polymer membranes and their CO's which are most widely used worldwide₂Permeation rate and separation factor. As can be seen from the results, the CO produced by the PVAm synthesized according to the invention₂The separation composite membrane has excellent performance and stronger application prospect.

TABLE 1 Polymer Membrane Performance for carbon dioxide separation

Drawings

FIG. 1 shows CO₂And (3) a structural schematic diagram of the separation composite membrane.

FIG. 2 shows CO₂Scanning electron microscope images of the surface structure of the separation composite membrane.

Detailed Description

For the technical scheme of synthesizing PNVF by NVF free radical polymerization, reference is made to the patent of invention, namely a preparation method of polyvinyl amine for capturing carbon dioxide separation membrane material, and the patent application number is as follows: 2018112184729.

1. preparing poly N-vinylformamide (PNVF) into a 9.5-10.5 wt% solution, and then adding hydrochloric acid into the solution until the hydrochloric acid concentration in the reaction solution is 8-12 wt%; stirring uniformly and adding into N₂Hydrolyzing at constant temperature of 65-75 ℃ for 4-5 h under protection to obtain polyvinyl amine hydrochloride (PVAm & HCl);

2. adding PVAm & HCl solution into excessive ethanol to precipitate to obtain white PVAm & HCl solid;

3. dissolving the obtained PVAm & HCl solid in deionized water, and preparing into 1-3 wt% aqueous solution; and adding excessive anion exchange resin into the solution, stirring until the pH of the solution is 12.0-13.0, and performing suction filtration to obtain a PVAm aqueous solution with the hydrolysis degree of 40-70%.

Coating the PVAm aqueous solution with the hydrolysis degree of 40-70% obtained in the step on the surface of an ultrafiltration membrane in a scraping mode to obtain CO with a flat and smooth surface₂Separating the composite membrane. FIG. 1 shows the CO produced₂The basic structure schematic diagram of the separation composite membrane, wherein PVAm with the hydrolysis degree of 40-70% is used as a separation layer and is coated on a support in a scraping mannerThe ultrafiltration membrane surface of the layer. FIG. 2 is CO₂An electron microscope image of the surface structure of the separation composite membrane proves that PVAm with the hydrolysis degree of 40-70% can be coated on the surface of the ultrafiltration membrane in a scraping manner to prepare CO with a flat and smooth surface₂Separating the composite membrane.

Example 1

1. PNVF was prepared as a 9.5 wt% solution, and then a hydrochloric acid solution was added to the solution until the hydrochloric acid concentration in the solution was 8.0 wt%, in N₂Hydrolyzing at the constant temperature of 65 ℃ for 4.2h under protection to obtain PVAmHCl;

2. adding the hydrolyzed polymer solution into excessive ethanol for precipitation to obtain white PVAmHCl solid;

3. dissolving the obtained polymer with deionized water to prepare a 2.5 wt% aqueous solution, and adding excessive strongly basic styrene type anion exchange resin until the pH value of the solution is 12.0; the mixture was filtered by suction through a G3 glass frit funnel to obtain a 2.5 wt% aqueous solution of PVAm.

Organic element test and calculation are carried out on the prepared PVAm, and the hydrolysis degree of the PVAm is 41.76%. Coating PVAm aqueous solution on polyacrylonitrile ultrafiltration membrane by scraping, and drying at constant temperature and humidity to obtain CO₂Separating the composite membrane. Then the separation membrane is placed in a mixed gas (CO)₂/N₂15/85、CO₂/H₂40/60、CO₂/CH₄10/90) and the test results are shown in Table 2.

Example 2

1. PNVF was prepared as a 9.8 wt% solution, and then a hydrochloric acid solution was added to the solution until the hydrochloric acid concentration in the solution was 8.4 wt%, in N₂Hydrolyzing at constant temperature of 73 ℃ for 4.5h under protection to obtain PVAmHCl;

3. the resulting polymer was dissolved in deionized water to prepare a 2.2 wt% aqueous solution, and then an excess of strongly basic styrene-type anion exchange resin was added to a solution pH of 12.3. The mixture was filtered by suction through a G3 glass frit funnel to obtain a 2.2 wt% aqueous solution of PVAm.

The prepared PVAm is subjected to organic treatmentElemental testing and calculation gave a PVAm hydrolysis of 51.78%. Spreading PVAm water solution on polyethersulfone ultrafiltration membrane, and drying at constant temperature and constant humidity to obtain CO₂Separating the composite membrane. Then the separation membrane is placed in a mixed gas (CO)₂/N₂15/85、CO₂/H₂40/60、CO₂/CH₄10/90) and the test results are shown in Table 2.

Example 3

1. PNVF was prepared as a 10.3 wt% solution, and then a hydrochloric acid solution was added to the solution until the hydrochloric acid concentration in the solution was 9.5 wt%, in N₂Hydrolyzing at the constant temperature of 68 ℃ for 4.1h under protection to obtain PVAmHCl.

2. The hydrolyzed polymer solution was precipitated by adding an excessive amount of ethanol to obtain white PVAmHCl solid.

3. The resulting polymer was dissolved in deionized water to prepare a 1.7 wt% aqueous solution, and then an excess of strongly basic polyethylene-type pyridine exchange resin was added to a solution pH of 12.2. The mixture was filtered by suction through a G3 glass frit funnel to obtain a 1.7 wt% aqueous solution of PVAm.

Organic element test and calculation are carried out on the prepared PVAm, and the hydrolysis degree of the PVAm is 46.36%. The PVAm aqueous solution is spread on a polyether-ether-ketone ultrafiltration membrane by scraping, and is dried under constant temperature and humidity to obtain CO₂Separating the composite membrane. Then the separation membrane is placed in a mixed gas (CO)₂/N₂15/85、CO₂/H₂40/60、CO₂/CH₄10/90) and the test results are shown in Table 2.

Example 4

1. PNVF was prepared as a 10.0 wt% solution, and then a hydrochloric acid solution was added to the solution until the hydrochloric acid concentration in the solution was 10.0 wt%, in N₂Hydrolyzing at constant temperature of 70 ℃ for 4.0h under protection to obtain PVAmHCl.

3. The resulting polymer was dissolved in deionized water to prepare a 1.3 wt% aqueous solution, and then an excess of strongly basic styrene-type anion exchange resin was added to a solution pH of 12.5. The mixture was filtered by suction through a G3 glass frit funnel to obtain a 1.3 wt% aqueous solution of PVAm.

Organic element test and calculation are carried out on the prepared PVAm, and the hydrolysis degree of the PVAm is 55.40%. Spreading PVAm water solution on polysulfone ultrafiltration membrane, and drying at constant temperature and humidity to obtain CO₂Separating the composite membrane. Then the separation membrane is placed in a mixed gas (CO)₂/N₂15/85、CO₂/H₂40/60、CO₂/CH₄10/90) and the test results are shown in Table 2.

Example 5

1. PNVF was prepared as a 9.7 wt% solution, and then a hydrochloric acid solution was added to the solution until the hydrochloric acid concentration in the solution was 10.4 wt%, in N₂Hydrolyzing at constant temperature of 74 ℃ for 4.9h under protection to obtain PVAmHCl.

3. The resulting polymer was dissolved in deionized water to prepare a 1.9 wt% aqueous solution, and then an excess of strongly basic polyethylene-type pyridine exchange resin was added to a solution pH of 12.2. The mixture was filtered by suction through a G3 glass frit funnel to obtain a 1.9 wt% aqueous solution of PVAm.

Organic element test and calculation are carried out on the prepared PVAm, and the hydrolysis degree of the PVAm is 63.01%. Coating PVAm aqueous solution on a polyvinylidene fluoride ultrafiltration membrane in a scraping way, and drying at constant temperature and constant humidity to obtain CO₂Separating the composite membrane. Then the separation membrane is placed in a mixed gas (CO)₂/N₂15/85、CO₂/H₂40/60、CO₂/CH₄10/90) and the test results are shown in Table 2.

Example 6

1. PNVF was prepared as a 10.1 wt% solution, and then a hydrochloric acid solution was added to the solution until the hydrochloric acid concentration in the solution became 11.4 wt% in N₂Hydrolyzing at 67 ℃ for 4.2h under protection to obtain PVAmHCl.

3. The resulting polymer was dissolved in deionized water to prepare a 2.0 wt% aqueous solution, and then an excess of styrene-type anion exchange resin was added to a solution pH of 12.1. The mixture was filtered by suction through a G3 glass frit funnel to obtain a 2.0 wt% aqueous solution of PVAm.

Organic element test and calculation are carried out on the prepared PVAm, and the hydrolysis degree of the PVAm is 61.15%. Spreading PVAm water solution on polycarbonate ultrafiltration membrane, and drying at constant temperature and humidity to obtain CO₂Separating the composite membrane. Then the separation membrane is placed in a mixed gas (CO)₂/N₂15/85、CO₂/H₂40/60、CO₂/CH₄10/90) and the test results are shown in Table 2.

Example 7

1. PNVF was prepared as a 10.4 wt% solution, and then a hydrochloric acid solution was added to the solution until the hydrochloric acid concentration in the solution was 12.0 wt%, in N₂Hydrolyzing at constant temperature of 73 ℃ for 4.9h under protection to obtain PVAmHCl.

3. The resulting polymer was dissolved in deionized water to prepare a 2.8 wt% aqueous solution, and then an excess of polyethylene-type pyridine exchange resin was added to a solution pH of 12.3. The mixture was filtered by suction through a G3 glass frit funnel to obtain a 2.8 wt% aqueous solution of PVAm.

Organic element test and calculation are carried out on the prepared PVAm, and the hydrolysis degree of the PVAm is 68.92%. Spreading PVAm water solution on polysulfone ultrafiltration membrane, and drying at constant temperature and humidity to obtain CO₂Separating the composite membrane. Then the separation membrane is placed in a mixed gas (CO)₂/N₂15/85、CO₂/H₂40/60、CO₂/CH₄10/90) and the test results are shown in Table 2.

Comparative example 1

1. PNVF was prepared as a 10.5 wt% solution, and then a hydrochloric acid solution was added to the solution until the hydrochloric acid concentration in the solution was 7.5 wt%, in N₂Hydrolyzing at constant temperature of 50 ℃ for 3.8h under protection to obtain PVAmHCl.

3. The resulting polymer was dissolved in deionized water to prepare a 2.9 wt% aqueous solution, and then an excess of strongly basic styrene-type anion exchange resin was added to a solution pH of 12.5. The mixture was filtered by suction through a G3 glass frit funnel to obtain a 2.6 wt% aqueous solution of PVAm.

Organic element test and calculation are carried out on the prepared PVAm, and the hydrolysis degree of the PVAm is 20.78%. Spreading PVAm water solution on polyethersulfone ultrafiltration membrane, and drying at constant temperature and constant humidity to obtain CO₂Separating the composite membrane. Then the separation membrane is placed in a mixed gas (CO)₂/N₂15/85、CO₂/H₂40/60、CO₂/CH₄10/90) and the test results are shown in Table 2.

Comparative example 2

Commercial PVAm purchased is subjected to organic element test and calculation, and the hydrolysis degree of the PVAm is 98.61%. Preparing the purchased PVAm into 1.2 wt% aqueous solution, coating the aqueous solution on a polysulfone ultrafiltration membrane by a doctor blade, and drying the solution at constant temperature and constant humidity to obtain CO₂Separating the composite membrane. Then the separation membrane is placed in a mixed gas (CO)₂/N₂15/85、CO₂/H₂40/60、CO₂/CH₄10/90) and the test results are shown in Table 2.

Test data and conclusions

Coating the prepared film with water solutions of different degrees of hydrolysis PVAm by blade coating, and using CO under different systems₂The permeation rate and separation factor are shown in table 2, respectively.

TABLE 2 CO separation systems for membranes of different degrees of hydrolysis PVAm₂Separation Performance

Note:¹permeation rate of CO₂Gas permeation rate in GPU;

²the separation factor is CO₂Gas permeation rate and N₂、H₂Or CH₄Ratio of gas permeation rates.

As can be seen from Table 2, in CO₂/N₂、CO₂/H₂And CO₂/CH₄CO prepared with commercial PVAm under system₂Compared with a separation composite membrane, the CO prepared from PVAm with the hydrolysis degree kept between 40 and 70 percent₂The separation composite membrane has higher CO₂Permeation rate and separation factor. With other CO in the world₂Compared with a separation membrane material, the CO prepared from PVAm with the hydrolysis degree kept between 40 and 70 percent₂The separation performance of the separation composite membrane is greatly improved, and the separation composite membrane has great potential for practical application.

While the methods and techniques of the present invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and/or modifications of the methods and techniques described herein may be made without departing from the spirit and scope of the invention. It is expressly intended that all such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and content of the invention.

Claims

1. The preparation method of the polyvinyl amine with the hydrolysis degree of 40-70% for preparing the carbon dioxide separation composite membrane is characterized by comprising the following steps of:

2. The method according to claim 1, wherein the concentration of the poly-N-vinylformamide solution in the step 1) is 9.5 to 10.5 wt%.

3. The method as set forth in claim 1, wherein in step 1) is N₂Hydrolyzing for 4-5 h at the constant temperature of 65-75 ℃ under protection.

4. The method according to claim 1, wherein the PVAm HCl solid in step 3) is dissolved in deionized water and prepared into 1-3 wt% aqueous solution.

5. The process as set forth in claim 1, wherein the anion exchange resin comprises a styrene-type anion exchange resin or a polyethylene-type pyridine resin.

6. The method for preparing the carbon dioxide separation composite membrane by using the polyvinyl amine with the concentration of 40-70% prepared by the method is characterized in that PVAm aqueous solution with the hydrolysis degree of 40-70% is blade-coated on the surface of an ultrafiltration membrane to obtain CO₂Separating the composite membrane.

7. The method of claim 6, wherein the ultrafiltration membrane comprises a polysulfone ultrafiltration membrane, a polyacrylonitrile ultrafiltration membrane, a polyethersulfone ultrafiltration membrane, a polyetheretherketone ultrafiltration membrane, a polyvinylidene fluoride ultrafiltration membrane, or a polycarbonate ultrafiltration membrane material.