A co2 gas separation membrane and a method for manufacturing the same

Abstract

The application provides a preparation method of a CO2 gas separation membrane, the separation membrane is composed of a base layer and a separation layer, the base layer is a self-polymerized microporous polymer, and the separation layer is a gel-assisted prepared film; the self-polymerized microporous polymer is prepared from tetrakisfluoroterephthalonitrile and tetrahydroxytetramethylspiro-linked indolizine through a condensation reaction; and the preparation method of the gel-assisted prepared film comprises the following steps: S1, preparing an oxidized sodium alginate solution containing aldehyde groups through an oxidation reaction of sodium alginate; S2, adding a polyamine compound and a rare earth metal salt into the oxidized sodium alginate solution containing aldehyde groups prepared in the step S1, then adding a polyethylene imine solution, and standing to form a gel; and adding trimesoyl chloride on the surface of the gel, drying the product after the reaction is completed, and obtaining the gel-assisted prepared film. The application further includes the CO2 gas separation membrane, and the CO2 gas separation membrane prepared by the application has strong selective permeation performance and high commercial value.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of functional polymer composite membranes, in particular to a CO2 gas separation membrane and a preparation method thereof. BACKGROUND

[0002] At present, the main CO2 separation and capture methods are alkali absorption method and membrane separation method. The former realizes CO2 separation and capture through the reversible chemical reaction between alkaline amine absorbent and CO2. This technology depends on heat energy to realize the regeneration of amine absorbent, has high energy consumption, large energy loss, is easy to cause secondary pollution due to oxidation and degradation, has high comprehensive cost of carbon capture, and is not conducive to large-scale application. In comparison, the membrane separation technology based on the principle of physical screening does not involve chemical reaction, does not cause secondary pollution, and does not depend on heat energy, so the energy loss is low. Especially for the industries such as steel and cement, the CO2 concentration of flue gas emitted is more than 20%, so the membrane separation for capturing CO2 is more attractive. However, research data shows that when treating coal flue gas (mainly CO2 / N2 mixed gas) of power plants, if the separation factor of the CO2 separation membrane is less than 20 and the CO2 permeation rate is less than 1000 GPU (1 GPU = 10 -6 cm 3 (STP) / (cm 2 ·s·cmHg) ), the economic cost of membrane separation for capturing CO2 is higher than that of alkali absorption method. Therefore, it has important practical application value to develop a gas separation membrane with high CO2 permeation rate and high CO2 / N2 separation factor. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a preparation method of a CO2 gas separation membrane, so as to solve the problems of large energy consumption, large energy loss, large pollution and high economic cost in the conventional preparation method.

[0004] In order to solve the above problems, the present application provides a preparation method of a CO2 gas separation membrane, the separation membrane is composed of a base layer and a separation layer, the base layer is a self-polymerized microporous polymer, and the separation layer is a gel-assisted prepared film.

[0005] The self-polymerized microporous polymer is prepared by condensation reaction of tetrafluoro-p-phenylenedicyanide and tetrahydroxytetramethylspiro-linked indolizine;

[0006] The preparation method of the gel-assisted prepared film comprises the following steps:

[0007] S1: preparing an aldehyde group-containing oxidized sodium alginate solution by oxidation reaction of sodium alginate;

[0008] S2: adding a polyamine-based compound and a rare earth metal salt into the aldehyde group-containing oxidized sodium alginate solution prepared in step S1, then adding a polyethylene imine solution, and forming a gel after standing, and adding trimesoyl chloride on the surface of the gel, and drying the product after the reaction to obtain a gel-assisted prepared film.

[0009] As a preferred solution, the preparation reaction formula of the self-polymerized microporous polymer is as follows:

[0010] Compound I and Compound II are tetrafluoroterephthalonitrile and tetrahydroxy tetramethyl spiro-linked indolizine, respectively.

[0011] As a preferred solution, the number average molecular weight of the self-polymerized microporous polymer is greater than or equal to 15000 g / mol.

[0012] As a preferred solution, in step S1, the aldehyde group content of the aldehyde group-containing oxidized sodium alginate solution is 10-40%.

[0013] As a preferred solution, in step S2, the polyamine-based compound is one or more of diethylenetriamine, tetraethylenepentamine, melamine, and an amine-based MOF obtained by reacting 2-amino terephthalic acid with zirconium chloride.

[0014] As a preferred solution, in step S2, the molar ratio of amine groups to rare earth metal ions in the polyamine-based compound is (15:1)-(3:1).

[0015] As a preferred solution, in step S2, the rare earth metal salt is one or more of cerium nitrate, lanthanum nitrate, and ytterbium chloride.

[0016] As a preferred solution, in step S2, the polyethylene imine solution and the aldehyde group-containing oxidized sodium alginate solution are a polyethylene imine solution and an aldehyde group-containing oxidized sodium alginate aqueous solution, and the volume ratio of the polyethylene imine solution to the aldehyde group-containing oxidized sodium alginate aqueous solution is 1:1.

[0017] As a preferred solution, in step S2, the concentration of the aldehyde group-containing oxidized sodium alginate aqueous solution and the polyethylene imine aqueous solution is 5-15 wt%.

[0018] Another technical problem to be solved by the present application is to provide a CO2 gas separation membrane to solve the problem of low permeation amount of conventional separation membranes.

[0019] The present application aims at the practical requirement of a gas separation membrane with high CO2 permeation flux and high CO2 / N2 separation factor in the process of coal flue gas treatment in power plants, and adopts a self-polymerized microporous polymer as a base layer, a gel-assisted prepared membrane as a separation layer to prepare a CO2 gas separation membrane.

[0020] To solve the above problems, the present application provides a CO2 gas separation membrane prepared by the above preparation method.

[0021] Based on the above scheme, the preparation method of the CO2 gas separation membrane of the present application and the CO2 gas separation membrane prepared thereby have the following advantages:

[0022] 1) The self-polymerized microporous polymer prepared by the condensation reaction of compound I and compound II is used as the base layer of the CO2 gas separation membrane, which can realize large flux permeation of CO2 gas. This is because the molecular chain of the self-polymerized microporous polymer has a twisted structure, the molecular chain stacking is irregular, and large pores are formed in the molecule, which is beneficial to the rapid permeation of gas.

[0023] 2) The gel-assisted preparation of the separation layer of the CO2 gas separation membrane can realize the ultra-thinning of the separation layer. Although the self-polymerized microporous polymer has large CO2 permeation flux, the CO2 / N2 separation factor is relatively small (about 12 or so), and therefore a separation layer needs to be covered on the surface of the self-polymerized microporous polymer. At present, the preparation of the separation layer is mainly realized by the oil-water two-phase interface reaction, but the separation layer formed by this method has a relatively large thickness (>100 nm), which will increase the gas diffusion permeation resistance and reduce the gas permeation flux. When the hydrogel is used to replace the aqueous solution and then reacts with the oil phase solution at the interface, due to the limitation of the diffusion rate of the reactants of the hydrogel, the interface reaction rate can be greatly slowed down, so that a thinner separation layer (the thickness of the separation layer prepared by the hydrogel replication is about 10 nm) can be formed, which can not only improve the CO2 / N2 molecular factor, but also will not cause the CO2 permeation flux to decrease due to the large mass transfer resistance caused by the too thick separation layer.

[0024] 3) The introduction of rare earth metal salt in the separation layer can form a complex with the polyamine compound, and the special 4f electron orbit of the rare earth ion can form a strong force with CO2, but cannot form a strong force with N2 molecules, so that the selective permeation of gas can be realized, which can greatly improve the CO2 / N2 separation factor of the gas separation membrane. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a scanning electron microscope graph of the cross section of the CO2 gas separation membrane. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] The present application provides a preparation method of a CO2 gas separation membrane, which is composed of a base layer and a separation layer, wherein the base layer is a self-polymerized microporous polymer, and the separation layer is a gel-assisted prepared film.

[0028] The self-polymerized microporous polymer is prepared by a condensation reaction of tetrakisfluoroterephthalonitrile and tetrahydroxy tetramethyl spiro-linked indolizine.

[0029] The preparation method of the gel-assisted prepared film comprises:

[0030] S1: preparing an aldehyde group-containing oxidized sodium alginate solution by an oxidation reaction of sodium alginate;

[0031] S2: adding a polyamine-based compound and a rare earth metal salt into the aldehyde group-containing oxidized sodium alginate solution prepared in the step S1, then adding a polyethylene imine solution, and forming a gel after standing; adding trimesoyl chloride on the surface of the gel, and drying the product after the reaction to obtain the gel-assisted prepared film.

[0032] The CO2 gas separation membrane provided by the present application is prepared by immersing the self-polymerized microporous polymer (as the base layer) into the oxidized sodium alginate aqueous solution configured during preparation of the separation layer, then adhering the produced film separation layer on the base layer as the reaction proceeds, so as to form the target CO2 gas separation composite membrane.

[0033] Preferably, the preparation reaction formula of the self-polymerized microporous polymer is as follows:

[0034] The compound I and the compound II are tetrakisfluoroterephthalonitrile and tetrahydroxy tetramethyl spiro-linked indolizine, respectively.

[0035] Preferably, the number average molecular weight of the self-polymerized microporous polymer is greater than or equal to 15000 g / mol.

[0036] Preferably, in the step S1, the aldehyde group content of the aldehyde group-containing oxidized sodium alginate solution is 10-40%.

[0037] Preferably, in the step S2, the polyamine-based compound is one or more of diethylenetriamine, tetraethylenepentamine, melamine, and an amine-based MOF, wherein the amine-based MOF is obtained by a reaction of 2-amino terephthalic acid and zirconium chloride.

[0038] Preferably, in step S2, the molar ratio of amine groups to rare earth metal ions in the polyamine compound is (15:1) to (3:1).

[0039] Preferably, in step S2, the rare earth metal salt is one or more of cerium nitrate, lanthanum nitrate, and ytterbium chloride.

[0040] Preferably, in step S2, the polyethyleneimine solution and the aldehyde-containing sodium alginate solution are aqueous solutions of polyethyleneimine solution and aldehyde-containing sodium alginate, and the volume ratio of the polyethyleneimine solution to the aldehyde-containing sodium alginate solution is 1:1.

[0041] Preferably, in step S2, the concentrations of the aldehyde-containing sodium alginate aqueous solution and the polyethyleneimine aqueous solution are both 5-15 wt%.

[0042] The present invention provides a CO2 gas separation membrane, which is prepared by the above-described preparation method.

[0043] The technical solution of the present invention will be described below through specific examples. In the following examples, compound I and compound II are tetrafluoroterephthalonitrile and tetrahydroxytetramethylspiroindole, respectively. Example

[0044] Compounds I and II were reacted at a molar ratio of 1:1 at 160°C with N-methylpyrrolidone (NMP) as solvent and potassium carbonate as acid adsorbent under nitrogen protection for 5 hours to obtain a self-polymerizing microporous polymer. The prepared self-polymerizing microporous polymer was dissolved in dichloromethane, and a 50 μm thick self-polymerizing microporous polymer membrane was obtained by solvent casting. This membrane was then used as the base layer for a CO2 gas separation membrane.

[0045] S1: Immerse the self-polymerized microporous membrane in a 10 wt% sodium alginate solution, and then add diethylenetriamine and cerium nitrate (molar ratio of amine to cerium ions is 5:1).

[0046] S2: Then, 10 wt% of a polyethyleneimine aqueous solution was added, and after standing for 3 minutes, a gel was formed. Subsequently, 0.1 wt% of a trimesoyl chlorohexane solution was poured onto the surface of the gel, and after reacting for 5 minutes, it was dried in an oven at 60°C to obtain a CO2 gas separation membrane. This CO2 gas separation membrane has a separation factor of 25 for a CO2 / N2 (volume ratio 50:50) mixed gas, and a CO2 permeability of 880 GPU (1 GPU = 10^2 Gbps). -6 cm 3 (STP) / (cm 2 ·s·cmHg)).

[0047] Figure 1 The image shows a scanning electron microscope image of the cross-section of the CO2 gas separation membrane prepared in Example 1 of the present invention. It can be seen from the image that a separation layer with a thickness of about 20 nanometers is formed on the surface of the base layer (self-polymerized microporous polymer) of the separation membrane. This separation layer not only improves the CO2 / N2 separation factor, but also has low mass transfer resistance and high CO2 gas permeability due to its ultrathin thickness. Example

[0048] Compounds I and II were reacted at a molar ratio of 1:1 at 160°C with N-methylpyrrolidone (NMP) as solvent and potassium carbonate as acid adsorbent under nitrogen protection for 5 hours to obtain a self-polymerizing microporous polymer. The prepared self-polymerizing microporous polymer was dissolved in dichloromethane, and a 50 μm thick self-polymerizing microporous polymer membrane was obtained by solvent casting. This membrane was then used as the base layer for a CO2 gas separation membrane.

[0049] S1: Immerse the self-polymerized microporous membrane in a 10 wt% sodium alginate solution, and then add tetraethylenepentamine and lanthanum nitrate (molar ratio of amine to lanthanum ions is 5:1).

[0050] S2: Then, add 10 wt% polyethyleneimine aqueous solution, let stand for 3 min to form a gel, and then pour 0.1 wt% trimesoyl chloride solution onto the surface of the gel. After reacting for 5 min, dry in an oven at 60℃ to obtain a CO2 gas separation membrane. This CO2 gas separation membrane has a separation factor of 20 for a CO2 / N2 (volume ratio 50:50) mixed gas, and a CO2 permeability of 750 GPU (1 GPU = 10^2 Gbps). -6 cm 3 (STP) / (cm 2 ·s·cmHg)). Example

[0051] Compounds I and II were reacted at a molar ratio of 1:1 at 160°C with N-methylpyrrolidone (NMP) as solvent and potassium carbonate as acid adsorbent under nitrogen protection for 5 hours to obtain a self-polymerizing microporous polymer. The prepared self-polymerizing microporous polymer was dissolved in dichloromethane, and a 50 μm thick self-polymerizing microporous polymer membrane was obtained by solvent casting. This membrane was then used as the base layer for a CO2 gas separation membrane.

[0052] S1: Immerse the self-polymerized microporous membrane in an 8 wt% sodium alginate solution, and then add amino MOF amine and cerium nitrate (molar ratio of amino group to cerium ion is 3:1).

[0053] S2: Then, add 8 wt% polyethyleneimine aqueous solution, let stand for 3 minutes to form a gel, and then pour 0.1 wt% trimesoyl chloride solution onto the surface of the gel. After reacting for 5 minutes, dry in an oven at 60°C to obtain a CO2 gas separation membrane. This CO2 gas separation membrane has a separation factor of 32 for a CO2 / N2 (volume ratio 50:50) mixed gas, and a CO2 permeability of 1100 GPUs (1 GPU = 10^2 Gbps). -6 cm 3 (STP) / (cm 2 ·s·cmHg)). Example

[0054] Compounds I and II were reacted at a molar ratio of 1:1 at 160°C with N-methylpyrrolidone (NMP) as solvent and potassium carbonate as acid adsorbent under nitrogen protection for 5 hours to obtain a self-polymerizing microporous polymer. The prepared self-polymerizing microporous polymer was dissolved in dichloromethane, and a 50 μm thick self-polymerizing microporous polymer membrane was obtained by solvent casting. This membrane was then used as the base layer for a CO2 gas separation membrane.

[0055] S1: Immerse the self-polymerized microporous membrane in a 15wt% sodium alginate solution, and then add melamine and ytterbium chloride (molar ratio of amine to ytterbium ions is 10:1).

[0056] S2: Then, add 15 wt% polyethyleneimine aqueous solution, let stand for 3 minutes to form a gel, and then pour 0.1 wt% trimesoyl chloride solution onto the surface of the gel. After reacting for 5 minutes, dry in an oven at 60°C to obtain a CO2 gas separation membrane. This CO2 gas separation membrane has a separation factor of 24 for a CO2 / N2 (volume ratio 50:50) mixed gas, and a CO2 permeability of 800 GPUs (1 GPU = 10^2 Gbps). -6 cm 3 (STP) / (cm 2 ·s·cmHg)). Example

[0057] Compounds I and II were reacted at a molar ratio of 1:1 at 160°C with N-methylpyrrolidone (NMP) as solvent and potassium carbonate as acid adsorbent under nitrogen protection for 5 hours to obtain a self-polymerizing microporous polymer. The prepared self-polymerizing microporous polymer was dissolved in dichloromethane, and a 50 μm thick self-polymerizing microporous polymer membrane was obtained by solvent casting. This membrane was then used as the base layer for a CO2 gas separation membrane.

[0058] S1: Immerse the self-polymerized microporous membrane in a 10 wt% sodium alginate solution, and then add diethylenetriamine, melamine and cerium nitrate (molar ratio of amine to cerium ions is 8:1).

[0059] S2: Then, 10 wt% of a polyethyleneimine aqueous solution was added, and after standing for 3 minutes, a gel was formed. Subsequently, 0.1 wt% of a trimesoyl chlorohexane solution was poured onto the surface of the gel, and after reacting for 5 minutes, it was dried in an oven at 60°C to obtain a CO2 gas separation membrane. This CO2 gas separation membrane has a separation factor of 28 for a CO2 / N2 (volume ratio 50:50) mixed gas, and a CO2 permeability of 730 GPU (1 GPU = 10^2 Gbps). -6 cm 3 (STP) / (cm 2 ·s·cmHg)).

[0060] The above embodiments further illustrate that the present invention provides a method for preparing a CO2 gas separation membrane with low energy consumption and environmental protection. The prepared CO2 gas separation membrane has high permeability and selectively permeates the gas, which can significantly improve the CO2 / N2 separation factor of the gas separation membrane.

[0061] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A method for preparing a CO2 gas separation membrane, characterized in that: The separation membrane consists of a base layer and a separation layer. The base layer is a self-polymerizing microporous polymer, and the separation layer is a thin film prepared with gel assistance. The self-polymerizing microporous polymer was prepared by polycondensation reaction of tetrafluoroterephthalonitrile and tetrahydroxytetramethylspiroindole. The method for preparing the gel-assisted thin film includes: S1: Sodium alginate solution containing aldehyde groups is prepared by oxidizing sodium alginate. S2: Add polyamine compounds and rare earth metal salts to the sodium alginate solution containing aldehyde groups prepared in step S1, then add polyethyleneimine solution, let stand to form a gel, add trimesoyl chloride to the surface of the gel, and dry the product after the reaction to obtain the gel-assisted prepared film.

2. The method for preparing the CO2 gas separation membrane according to claim 1, characterized in that: The preparation reaction formula of the self-polymerizing microporous polymer is as follows: Compound I and compound II are tetrafluoroterephthalonitrile and tetrahydroxytetramethylspiroindole, respectively.

3. The method for preparing the CO2 gas separation membrane according to claim 1, characterized in that: The number-average molecular weight of the self-polymerizing microporous polymer is greater than or equal to 15000 g / mol.

4. The method for preparing the CO2 gas separation membrane according to claim 1, characterized in that: In step S1, the aldehyde content of the aldehyde-containing sodium alginate solution is 10-40%.

5. The method for preparing the CO2 gas separation membrane according to claim 1, characterized in that: In step S2, the polyamine compound is one or more of diethylenetriamine, tetraethylenepentamine, melamine, and amino MOF, and the amino MOF is obtained by reacting 2-aminoterephthalic acid with zirconium chloride.

6. The method for preparing the CO2 gas separation membrane according to claim 1, characterized in that: In step S2, the molar ratio of amino groups to rare earth metal ions is (15:1) to (3:1), based on the number of moles of amino groups in the polyamine compound and the number of moles of rare earth metal ions in the rare earth metal salt.

7. The method for preparing the CO2 gas separation membrane according to claim 1, characterized in that: In step S2, the rare earth metal salt is one or more of cerium nitrate, lanthanum nitrate, and ytterbium chloride.

8. The method for preparing the CO2 gas separation membrane according to claim 1, characterized in that: In step S2, the polyethyleneimine solution and the aldehyde-containing sodium alginate solution are aqueous solutions of polyethyleneimine solution and aldehyde-containing sodium alginate, and the volume ratio of the polyethyleneimine solution to the aldehyde-containing sodium alginate solution is 1:

1.

9. The method for preparing the CO2 gas separation membrane according to claim 1, characterized in that: In step S2, the concentrations of the aldehyde-containing sodium alginate aqueous solution and the polyethyleneimine aqueous solution are both 5-15 wt%.

10. A CO2 gas separation membrane, characterized in that: The separation membrane is prepared by the preparation method according to any one of claims 1-9.

Images