Ultrathin polyethylene oxide-based carbon capture film, and preparation method therefor and use thereof

Abstract

The present invention provides an ultrathin polyethylene oxide-based carbon capture film, and a preparation method therefor and the use thereof. The ultrathin polyethylene oxide-based carbon capture film is of a three-layer composite structure, successively comprising a polyethylene oxide-based separation layer having a strong CO2 affinity, a modified interface modification layer and a support layer from top to bottom. The separation layer is prepared by carrying out cross-linking reaction of PEO and a silicone rubber monomer, and thus contains a large number of ether oxygen groups preferentially adsorbing CO2, and, by means of the introduction of a silicone rubber chain segment, overcomes the structural defects of high cohesive energy and low permeability of pure PEO films, thus achieving high gas molecule permeability. Aiming at the problem of poor compatibility between the interface modification layer and the separation layer, the surface properties of the interface modification layer are improved by utilizing a simple and controllable UV / O3 treatment method which is easy to scale up, thus achieving uniform and defect-free coating of the ultrathin separation layer. The present invention involves a simple preparation process, can easily realize scale-up preparation, and achieve excellent carbon capture performance.

Description

Ultra-thin polyethylene oxide carbon capture membrane and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of gas separation membranes, in particular to an ultra-thin polyethylene oxide carbon capture membrane and a preparation method and application thereof. Background Art

[0002] Global warming has become one of the major environmental issues facing countries around the world. The main reason is the excessive emission of greenhouse gases, especially carbon dioxide. Efficient carbon capture from factory flue gases is crucial to reducing CO2 emissions and achieving carbon neutrality. Compared with traditional carbon capture technologies, membrane separation technology has the advantages of simple operation, low cost, low energy consumption, and environmental friendliness, and is considered to be the second generation of carbon capture technology. Due to the large volume flow of flue gas and low CO2 concentration, the selection of membrane materials with high permeability and moderate selectivity is more conducive to improving the economic competitiveness of membrane carbon capture technology. Therefore, the ultra-thin composite membrane composed of an ultra-thin separation layer, an interface modification layer and a support layer has good application prospects. The introduction of the interface modification layer can construct a non-porous surface, thereby inhibiting the separation layer solution from invading the porous support layer to form defects during coating, and the ultra-thin thickness of the separation layer can minimize the diffusion resistance and achieve high permeability.

[0003] The intrinsic properties of the separation layer material are the core factors that determine the separation performance of the composite membrane. Polyethylene oxide (PEO) is one of the CO2 separation membrane materials that has received extensive research attention. The large number of ether oxygen groups in polyethylene oxide can form a strong dipole-quadrupole effect with CO2 molecules, thereby improving the solubility selectivity of CO2 in the membrane. However, the polymer chains in pure polyethylene oxide membranes are tightly arranged and have a high degree of crystallinity, resulting in extremely large gas diffusion resistance, unsatisfactory gas permeability, and poor mechanical strength of the membrane material. Currently commercial polyethylene oxide-containing membrane materials, such as polyether block polyamide, have low intrinsic permeability. The preparation of amorphous cross-linked polyethylene oxide based on epoxy ring-opening reaction is an effective means to solve the above problems and can achieve a several-fold increase in CO2 permeability. However, cross-linked polyethylene oxide membrane materials still have two problems: (1) The hydroxyl groups generated during the cross-linking reaction increase the cohesive energy of the polymer, and the CO2 permeability is still not ideal; (2) The current research on cross-linked polyethylene oxide membranes is to prepare homogeneous membranes with a thickness of 150-200 microns, and there are no reports on the preparation of composite membranes.

[0004] When designing the interface modification layer, a key issue that needs to be considered is the poor matching and bonding between the interface modification layer and the separation layer. The silicone rubber material (polydimethylsiloxane) commonly used for the interface modification layer has a relatively hydrophobic surface, while the separation layer is usually a hydrophilic material, making it difficult to achieve ultra-thin and defect-free coating on the hydrophobic surface. Introducing an additional transition layer between the interface modification layer and the separation layer through surface coating is an effective strategy, but it significantly prolongs and complicates the manufacturing process. Chinese patent CN115608177B uses plasma treatment to achieve hydrophilization of the silicone rubber surface, but due to the size limitations of the plasma equipment, this method is difficult to achieve scale-up production.

[0005] Based on the above analysis, the ultra-thin composite membranes currently used for CO2 separation mainly face the following two problems: (1) It is necessary to synthesize a polyethylene oxide-based membrane material with a strong affinity for CO2 as the separation layer, and to perform structural design to reduce cohesive energy and improve permeability; (2) It is necessary to use a simple, controllable, and easily scalable method to modify the surface of the interface modification layer to optimize the compatibility and bonding with the separation layer, thereby realizing the preparation of ultra-thin composite membranes. Summary of the Invention

[0006] In view of the above-mentioned prior art, the problem that the present invention needs to solve is: the intrinsic permeability of the separation layer membrane material in the carbon capture composite membrane is low, and the poor compatibility between the separation layer and the interface modification layer makes it difficult to achieve uniform coating of the ultra-thin separation layer. Therefore, the present invention proposes an ultra-thin polyethylene oxide carbon capture membrane and a preparation method thereof.

[0007] The present invention provides an ultra-thin polyethylene oxide-based carbon capture membrane having a three-layer composite structure, which comprises, from top to bottom, a polyethylene oxide separation layer with strong CO2 affinity, a modified interface modification layer, and a support layer.

[0008] The present invention also provides a method for preparing an ultra-thin polyethylene oxide carbon capture membrane, comprising the following steps:

[0009] Step 1, dissolving polyethylene glycol diglycidyl ether, (poly(dimethylsiloxane) diglycidyl ether) and polyetheramine in a first solvent, heating and reacting for a period of time to obtain a polyethylene oxide-silicone rubber solution;

[0010] Step 2: dissolving the hydroxyl-terminated silicone rubber, the catalyst and the cross-linking agent in a second solvent, heating the reaction for a period of time, and then coating the solution on the surface of the base film. After drying at room temperature, the solution is subjected to UV / O3 treatment to obtain a modified interface modification layer.

[0011] Step 3: coating the polyethylene oxide-silicone rubber casting solution on the surface of the modified interface modification layer, and thermally crosslinking the film coated with the mixed solution to obtain an ultra-thin polyethylene oxide-based carbon capture membrane.

[0012] Preferably, in step 1, the molar ratio of polyethylene glycol diglycidyl ether, poly(dimethylsiloxane) diglycidyl ether, and polyetheramine is 1.4-1.8:0.2-0.6:1, and the total mass fraction of the solute is 0.7-2wt%.

[0013] Preferably, in step 1, the first solvent is an ethanol / water mixed solvent, and the mass fraction of ethanol is 70-90wt%.

[0014] Preferably, in step 1, the heating reaction temperature is 50-100° C. and the time is 2-4 h.

[0015] Preferably, in step 2, the UV / O3 treatment time is 90-150s, and the treatment temperature is 25-40 o C.

[0016] Preferably, in step 3, the coating method is blade coating, spin coating or spray coating.

[0017] Preferably, in step 3, the thermal cross-linking temperature is 60-100° C. and the time is 2 hours.

[0018] The present invention also provides an application of the ultra-thin polyethylene oxide-based carbon capture membrane in separating CO2 / N2 mixed gas.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention synthesizes a polymer material rich in polyethylene oxide groups through a covalent cross-linking reaction between amino-terminated polyethylene oxide molecules (polyetheramine) and epoxy-terminated polyethylene oxide molecules (polyethylene glycol diglycidyl ether). During the reaction, epoxy-terminated silicone rubber segments are introduced into the molecule. The silicone rubber's inherent high chain mobility and non-polar groups interfere with the formation of hydrogen bonds between the molecular chains in the synthesized material, increasing the free volume and improving the permeability of gas molecules, thereby obtaining a separation layer membrane material with high gas permeability. Furthermore, the interface modification layer is hydrophilically modified through a simple, controllable, and easily scalable UV / O3 treatment. Under UV irradiation, O2 in the air is oxidized to O3. The combined action of UV and O3 converts the hydrophobic methyl groups on the silicone rubber surface into polar hydrophilic groups, such as silanol and carbonyl groups, improving the surface wettability of the interface modification layer and achieving uniform, defect-free coating of the synthesized high-permeability separation layer membrane material on the interface modification layer. In order to obtain an ultrathin carbon capture membrane with higher separation performance, the preparation conditions such as UV / O3 treatment time, treatment temperature, separation layer polymer concentration, and thermal cross-linking temperature were optimized.

[0021] 2. The present invention enables efficient separation of CO2 / N2 mixtures. First, a highly permeable silicone rubber interface modification layer is developed, and its surface hydrophilicity is enhanced through UV / O3 treatment, improving interlayer compatibility and bonding. Second, highly mobile silicone rubber segments are introduced into the cross-linked polyethylene oxide to increase its free volume and reduce gas diffusion resistance. Finally, a polyethylene oxide-silicone rubber solution is applied to the surface of the modified interface modification layer, achieving uniform and defect-free coating of an ultrathin separation layer, thereby producing an ultrathin polyethylene oxide-based carbon capture membrane.

[0022] 3. By optimizing the ratio of polyethylene oxide and silicone rubber in the separation layer and the UV / O3 treatment conditions on the surface of the silicone rubber interface modification layer, the present invention prepares an ultra-thin composite membrane with a CO2 permeability of 2200 GPU and a CO2 / N2 selectivity of 27 for CO2 / N2 separation at 25°C.

[0023] 4. The preparation method of the present invention is simple and controllable. The resulting ultra-thin polyethylene oxide-based carbon capture membrane represents the first ultra-thin cross-linked polyethylene oxide polymer achieved through a simple coating method. Compared to commercial membrane materials and pure polyethylene oxide composite membranes, the present invention has a higher CO2 permeability. It can be used in flue gas carbon capture processes and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a flow chart of the preparation of an ultra-thin polyethylene oxide-based carbon capture membrane in Example 1 of the present invention.

[0025] FIG. 2 is a diagram of the polyethylene oxide separation layer membrane material in Example 1 of the present invention. 13 C-NMR spectrum.

[0026] FIG3 shows the water contact angle of the membrane surface before and after ultraviolet ozone treatment in Example 1 of the present invention.

[0027] FIG4 is a surface electron microscope image of the silicone rubber interface modification layer in Example 1 of the present invention.

[0028] FIG5 is a surface electron micrograph of the ultrathin polyethylene oxide carbon capture membrane obtained in Example 1 of the present invention.

[0029] FIG6 is a cross-sectional electron micrograph of the ultrathin polyethylene oxide carbon capture membrane obtained in Example 1 of the present invention. Implementation Method

[0030] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below with reference to specific illustrations. Example 1

[0031] A method for preparing an ultra-thin polyethylene oxide carbon capture membrane, as shown in FIG1 , comprises the following steps:

[0032] Step 1: Add polyethylene glycol diglycidyl ether, poly(dimethylsiloxane) diglycidyl ether, and polyetheramine to a 30 mL ethanol / water mixture (70 wt% ethanol) at a molar ratio of 1.6:0.4:1 and thoroughly stir to dissolve. The epoxy and amino groups react in a 2:1 ratio, resulting in a molar ratio of 2:1 between the epoxy-terminated molecules (polyethylene glycol diglycidyl ether and poly(dimethylsiloxane) diglycidyl ether) and the amino-terminated molecules (polyetheramine). The total mass fraction of the three molecules is 1 wt%. The mixture is reacted at 80°C for 3 hours to fully crosslink the epoxy and amino groups. Condensed water is used for reflux during the reaction. The flask containing the reaction solution is placed in an ultrasonic cleaner for 10 minutes for ultrasonic degassing to obtain a polyethylene oxide-silicone rubber solution.

[0033] From synthetic polyethylene oxide-silicone rubber 13 As can be seen from the C-NMR graph (Figure 2), in addition to the characteristic peak of -CH2-O- belonging to polyethylene glycol diglycidyl ether at δ = 71.0237 ppm, the characteristic peak of -OCC belonging to polyetheramine at δ = 74.3993 ppm, and the characteristic peak of -CH3 belonging to polyetheramine at δ = 17.8453 ppm, a characteristic peak belonging to poly(dimethylsiloxane) diglycidyl ether was observed at δ = 0.9183 ppm, confirming the introduction of silicone rubber segments.

[0034] Step 2: Dissolve the hydroxyl-terminated silicone rubber, ethyl orthosilicate and dibutyltin dilaurate in n-heptane. The mass ratio of n-heptane: hydroxyl-terminated silicone rubber: ethyl orthosilicate: dibutyltin dilaurate is 100:1:1:0.1. o The obtained solution was coated on the surface of the polyacrylonitrile support and dried at room temperature for 24 hours to obtain the silicone rubber interface modification layer. The UV-ozone cleaning machine was turned on and the irradiation distance of the equipment was adjusted to 3 cm. After the equipment was preheated, the film coated with the interface modification layer was placed face up in the UV-ozone cleaning machine for 30 o After UV / O3 treatment at 47°C for 120 s, the membrane was taken out from the UV-ozone cleaning machine to obtain a modified interface modification layer.

[0035] During the UV / O3 treatment, ultraviolet light can produce two different wavelengths (185 nm and 254 nm). The 185 nm ultraviolet light can oxidize O2 in the air into O3, while the 254 nm ultraviolet light can break the chemical bonds in the polymer. The combined effect of ultraviolet light and O3 oxidation produces hydrophilic polar groups on the surface of the silicone rubber. After UV / O3 treatment, the water contact angle of the membrane surface increases from 109 o Reduced to 82 o (Figure 3), demonstrating a significant improvement in hydrophilicity.

[0036] Step 3: coating the polyethylene oxide-silicone rubber solution on the surface of the modified interface modification layer, and placing the film coated with the mixed solution in an oven at 80° C. for heat treatment for 2 hours to promote further cross-linking between molecules to obtain an ultra-thin polyethylene oxide-based carbon capture membrane.

[0037] As shown in Figure 4, the surface of the treated silicone rubber interface modification layer exhibits noticeable wrinkles. This is primarily due to the use of a low-concentration, highly cross-linked silicone rubber solution, which rapidly cross-links the membrane surface during the coating process, forming wrinkles. As shown in Figure 5, after coating with the polyethylene oxide-silicone rubber solution, the surface is smooth and the wrinkles are completely covered, demonstrating a uniform, defect-free coating of the polyethylene oxide-silicone rubber separation layer. A cross-section of the composite membrane is shown in Figure 6, showing the combined thickness of the interface modification layer and separation layer is approximately 240 nm.

[0038] The ultra-thin polyethylene oxide carbon capture membrane prepared in Example 1 was o C, the CO2 permeability for CO2 / N2 separation is 2200GPU and the CO2 / N2 selectivity is 27. Example 2

[0039] A method for preparing an ultra-thin polyethylene oxide carbon capture membrane comprises the following steps:

[0040] Step 1: Add polyethylene glycol diglycidyl ether, poly(dimethylsiloxane) diglycidyl ether), and polyetheramine to 30 mL of an ethanol / water mixture (80 wt% ethanol) at a molar ratio of 1.8:0.2:1 and thoroughly stir to dissolve. The total mass fraction of the three molecules is 0.7 wt%. The mixture is reacted at 50°C for 4 hours to allow for full cross-linking between the epoxy and amino groups. Condensed water is used for reflux during the reaction. The flask containing the reaction solution is placed in an ultrasonic cleaner for 10 minutes for ultrasonic degassing to obtain a polyethylene oxide-silicone rubber solution.

[0041] Step 2: Dissolve the hydroxyl-terminated silicone rubber, ethyl orthosilicate and dibutyltin dilaurate in n-heptane. The mass ratio of n-heptane: hydroxyl-terminated silicone rubber: ethyl orthosilicate: dibutyltin dilaurate is 100:1:1:0.1. o The obtained solution was coated on the surface of the polyacrylonitrile support and dried at room temperature for 24 hours to obtain the silicone rubber interface modification layer. The UV-ozone cleaning machine was turned on and the irradiation distance of the equipment was adjusted to 3 cm. After the equipment was preheated, the film coated with the interface modification layer was placed face up in the UV-ozone cleaning machine for 25 o After UV / O3 treatment at 47°C for 90 seconds, the membrane was taken out from the UV-ozone cleaning machine to obtain a modified interface modification layer.

[0042] Step 3: coating the polyethylene oxide-silicone rubber solution on the surface of the modified interface modification layer, and placing the film coated with the mixed solution in a 60° C. oven for heat treatment for 2 hours to promote further cross-linking between molecules to obtain an ultra-thin polyethylene oxide-based carbon capture membrane.

[0043] The ultra-thin polyethylene oxide carbon capture membrane prepared in Example 2 was o C, the CO2 permeability for CO2 / N2 separation is 3214GPU, and the CO2 / N2 selectivity is 16. Example 3

[0044] A method for preparing an ultra-thin polyethylene oxide carbon capture membrane comprises the following steps:

[0045] Step 1: Add polyethylene glycol diglycidyl ether, poly(dimethylsiloxane) diglycidyl ether), and polyetheramine to 30 mL of an ethanol / water mixture (70 wt % ethanol) at a molar ratio of 1.4:0.6:1 and thoroughly stir to dissolve. The total mass fraction of the three molecules is 2 wt %. The mixture is reacted at 100°C for 2 hours to allow for full cross-linking between the epoxy and amino groups. Condensed water is used for reflux during the reaction. The flask containing the reaction solution is placed in an ultrasonic cleaner for 10 minutes for ultrasonic degassing to obtain a polyethylene oxide-silicone rubber solution.

[0046] Step 2: Dissolve the hydroxyl-terminated silicone rubber, ethyl orthosilicate and dibutyltin dilaurate in n-heptane. The mass ratio of n-heptane: hydroxyl-terminated silicone rubber: ethyl orthosilicate: dibutyltin dilaurate is 100:1:1:0.1. o The obtained solution was coated on the surface of the polyacrylonitrile support and dried at room temperature for 24 hours to obtain the silicone rubber interface modification layer. The UV-ozone cleaning machine was turned on and the irradiation distance of the equipment was adjusted to 3 cm. After the equipment was preheated, the film coated with the interface modification layer was placed face up in the UV-ozone cleaning machine at 40 o After UV / O3 treatment at 47°C for 150 s, the membrane was taken out from the UV-ozone cleaning machine to obtain a modified interface modification layer.

[0047] Step 3: coating the polyethylene oxide-silicone rubber solution on the surface of the modified interface modification layer, and placing the membrane coated with the mixed solution in a 100° C. oven for heat treatment for 2 hours to promote further cross-linking between molecules to obtain an ultra-thin polyethylene oxide-based carbon capture membrane.

[0048] The ultra-thin polyethylene oxide carbon capture membrane prepared in Example 3 was o C, the CO2 permeability for CO2 / N2 separation is 1325GPU and the CO2 / N2 selectivity is 22. Example 4

[0049] A method for preparing an ultra-thin polyethylene oxide carbon capture membrane comprises the following steps:

[0050] Step 1: Add polyethylene glycol diglycidyl ether, poly(dimethylsiloxane) diglycidyl ether, and polyetheramine to 30 mL of an ethanol / water mixture (90 wt % ethanol) at a molar ratio of 1.6:0.4:1 and thoroughly stir to dissolve. The total mass fraction of the three molecules is 1 wt %. React at 50°C for 4 h to allow for sufficient cross-linking between the epoxy and amino groups. Condensed water is used for reflux during the reaction. The flask containing the reaction solution is placed in an ultrasonic cleaner for 10 minutes for ultrasonic degassing to obtain a polyethylene oxide-silicone rubber solution.

[0051] Step 2: Dissolve the hydroxyl-terminated silicone rubber, ethyl orthosilicate and dibutyltin dilaurate in n-heptane. The mass ratio of n-heptane: hydroxyl-terminated silicone rubber: ethyl orthosilicate: dibutyltin dilaurate is 100:1:1:0.1. o The obtained solution was coated on the surface of the polyacrylonitrile support and dried at room temperature for 24 hours to obtain the silicone rubber interface modification layer. The UV-ozone cleaning machine was turned on and the irradiation distance of the equipment was adjusted to 3 cm. After the equipment was preheated, the film coated with the interface modification layer was placed face up in the UV-ozone cleaning machine for 25 o After UV / O3 treatment at 47°C for 120 s, the membrane was taken out from the UV-ozone cleaning machine to obtain a modified interface modification layer.

[0052] Step 3: coating the polyethylene oxide-silicone rubber solution on the surface of the modified interface modification layer, and placing the film coated with the mixed solution in an oven at 80° C. for heat treatment for 2 hours to promote further cross-linking between molecules to obtain an ultra-thin polyethylene oxide-based carbon capture membrane.

[0053] The ultra-thin polyethylene oxide carbon capture membrane prepared in Example 4 was o C, the CO2 permeability for CO2 / N2 separation is 1537GPU and the CO2 / N2 selectivity is 32. Comparative Example 1

[0054] A method for preparing an ultrathin polyethylene oxide carbon capture membrane is described. The method differs from Example 1 in that the silicone rubber interface modification layer is not subjected to UV / O3 treatment. The steps are as follows:

[0055] Step 1: Add polyethylene glycol diglycidyl ether, poly(dimethylsiloxane) diglycidyl ether), and polyetheramine to 30 mL of an ethanol / water mixture (70 wt % ethanol) at a molar ratio of 1.6:0.4:1 and thoroughly stir to dissolve. The total mass fraction of the three molecules is 1 wt %. The mixture is reacted at 80°C for 3 hours to allow for full cross-linking between the epoxy and amino groups. Condensed water is used for reflux during the reaction. The flask containing the reaction solution is placed in an ultrasonic cleaner for 10 minutes for ultrasonic degassing to obtain a polyethylene oxide-silicone rubber solution.

[0056] Step 2: Dissolve the hydroxyl-terminated silicone rubber, ethyl orthosilicate and dibutyltin dilaurate in n-heptane. The mass ratio of n-heptane: hydroxyl-terminated silicone rubber: ethyl orthosilicate: dibutyltin dilaurate is 100:1:1:0.1. o The obtained solution was coated on the surface of a polyacrylonitrile support and dried at room temperature for 24 hours to obtain a silicone rubber interface modification layer.

[0057] Step 3: coating the polyethylene oxide-silicone rubber solution on the surface of the silicone rubber interface modification layer, and placing the film coated with the mixed solution in an oven at 80° C. for heat treatment for 2 hours to promote further cross-linking between molecules to obtain an ultra-thin polyethylene oxide-based carbon capture membrane.

[0058] The ultra-thin polyethylene oxide carbon capture membrane prepared in Comparative Example 1 was o C, the CO2 permeability of the CO2 / N2 mixture separation is 12305GPU, and the CO2 / N2 selectivity is 11, which is comparable to the separation performance of the interface modification layer, indicating that when UV / O3 treatment is not performed, the separation layer is difficult to coat onto the surface of the interface modification layer due to the surface hydrophobicity of the interface modification layer. Comparative Example 2

[0059] A method for preparing an ultrathin polyether block polyamide carbon capture membrane is described. The main difference from Example 1 is that the separation layer uses commercial polyether block polyamide (Pebax-1657) instead of polyethylene oxide-silicone rubber membrane material. The steps are as follows:

[0060] Step 1: Add polyether block polyamide particles to 30 mL of ethanol / water mixed solvent, wherein the mass fraction of ethanol is 70 wt% and the polymer concentration is 1 wt%, and stir at 80 ° C for 5 hours to completely dissolve it. During the process, condensed water is used for reflux to obtain a polyether block polyamide casting solution.

[0061] Step 2: Dissolve the hydroxyl-terminated silicone rubber, ethyl orthosilicate and dibutyltin dilaurate in n-heptane. The mass ratio of n-heptane: hydroxyl-terminated silicone rubber: ethyl orthosilicate: dibutyltin dilaurate is 100:1:1:0.1. oThe obtained solution was coated on the surface of the polyacrylonitrile support and dried at room temperature for 24 hours to obtain the silicone rubber interface modification layer. The UV-ozone cleaning machine was turned on and the irradiation distance of the equipment was adjusted to 3 cm. After the equipment was preheated, the film coated with the interface modification layer was placed face up in the UV-ozone cleaning machine for 30 o After UV / O3 treatment at 47°C for 120 s, the membrane was taken out from the UV-ozone cleaning machine to obtain a modified interface modification layer.

[0062] Step 3: applying the polyether block polyamide casting solution to the surface of the modified interface modification layer, and heat-treating the mixture in an oven at 60° C. for 2 h to obtain an ultra-thin polyether block polyamide carbon capture membrane.

[0063] The ultra-thin polyether block polyamide carbon capture membrane prepared in Comparative Example 2 was o C, the CO2 permeability for the separation of CO2 / N2 mixture is 358GPU and the CO2 / N2 selectivity is 49. Comparative Example 3

[0064] A method for preparing an ultrathin polyethylene oxide carbon capture membrane is described. The main difference from Example 1 is that poly(dimethylsiloxane) diglycidyl ether is not added to the separation layer solution, that is, no silicone rubber segment is introduced. The steps are as follows:

[0065] Step 1: Add polyethylene glycol diglycidyl ether and polyetheramine in a 2:1 molar ratio to 30 mL of an ethanol / water mixture (70 wt% ethanol) and stir thoroughly to dissolve. The combined mass fraction of the two molecules is 1 wt%. The mixture is reacted at 80°C for 3 hours to allow for full cross-linking between the epoxy and amino groups. Condensed water is used for reflux during the reaction. The flask containing the reaction solution is placed in an ultrasonic cleaner for 10 minutes for ultrasonic degassing to obtain a polyethylene oxide casting solution.

[0066] Step 2: Dissolve the hydroxyl-terminated silicone rubber, ethyl orthosilicate and dibutyltin dilaurate in n-heptane. The mass ratio of n-heptane: hydroxyl-terminated silicone rubber: ethyl orthosilicate: dibutyltin dilaurate is 100:1:1:0.1. o The obtained solution was coated on the surface of the polyacrylonitrile support and dried at room temperature for 24 hours to obtain the silicone rubber interface modification layer. The UV-ozone cleaning machine was turned on and the irradiation distance of the equipment was adjusted to 3 cm. After the equipment was preheated, the film coated with the interface modification layer was placed face up in the UV-ozone cleaning machine for 30 o After UV / O3 treatment at 47°C for 120 s, the membrane was taken out from the UV-ozone cleaning machine to obtain a modified interface modification layer.

[0067] Step 3: coating the polyethylene oxide casting solution on the surface of the modified interface modification layer, and placing the film coated with the mixed solution in an oven at 80° C. for heat treatment for 2 hours to promote further cross-linking between molecules to obtain an ultra-thin polyethylene oxide-based carbon capture membrane.

[0068] The ultra-thin polyethylene oxide carbon capture membrane prepared in Comparative Example 3 was o C, the CO2 permeability for CO2 / N2 separation is 915GPU and the CO2 / N2 selectivity is 42.

[0069] The comparison of CO2 permeability and CO2 / N2 selectivity of the membranes prepared in various embodiments of the present invention and comparative examples is shown in Table 1:

[0070] Table 1

[0071] Item Membrane CO2 Permeability (GPU) Membrane CO2 / N2 Selectivity Example 1 2 2 0 0 2 7 Example 2 3 2 1 4 1 6 Example 3 1 3 2 5 2 2 Example 4 1 5 3 7 3 2 Comparative Example 1 1 2 3 0 5 1 1 Comparative Example 2 3 5 8 4 9 Comparative Example 3 9 1 5 4 2

[0072] Conclusion: Analysis of the above test characterization results indicates that the ultra-thin polyethylene oxide-based carbon capture membrane prepared by the present invention has excellent separation performance for CO2 / N2 separation. The ultra-thin polyethylene oxide-based carbon capture membrane with the best overall performance has a CO2 permeability of 2200 GPU and a CO2 / N2 selectivity of 27. The present invention introduces silicone rubber segments into the cross-linked polyethylene oxide polymer to obtain a separation layer membrane material with gas permeability. Furthermore, by subjecting the silicone rubber interface modification layer to a simple, controllable, and easily scalable UV / O3 treatment, the surface wettability of the interface modification layer is improved, thereby achieving uniform, defect-free coating of the synthesized high-permeability separation layer membrane material on the surface of the interface modification layer.

[0073] The above are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structures made using the contents of the present invention's description and drawings, directly or indirectly applied to other related technical fields, are also within the patent protection scope of the present invention.

[0074]

Claims

1. An ultra-thin polyethylene oxide-based carbon capture membrane, characterized in that: It has a three-layer composite structure, which includes, from top to bottom, a polyethylene oxide separation layer with strong CO2 affinity, a modified interface modification layer, and a support layer.

2. A method for preparing an ultra-thin polyethylene oxide-based carbon capture membrane, characterized in that: The steps include: Step 1, dissolving polyethylene glycol diglycidyl ether, (poly(dimethylsiloxane) diglycidyl ether) and polyetheramine in a first solvent, heating and reacting for a period of time to obtain a polyethylene oxide-silicone rubber solution; Step 2, dissolving the hydroxyl-terminated silicone rubber, the catalyst and the cross-linking agent in a second solvent, heating the reaction for a period of time and coating the resultant on the surface of the base film, drying at room temperature and then performing UV / O3 treatment to obtain a modified interface modification layer; Step 3: coating the polyethylene oxide-silicone rubber casting solution on the surface of the modified interface modification layer, and thermally crosslinking the film coated with the mixed solution to obtain an ultra-thin polyethylene oxide-based carbon capture membrane.

3. The preparation method according to claim 2, characterized in that: In step 1, the molar ratio of polyethylene glycol diglycidyl ether, poly(dimethylsiloxane) diglycidyl ether, and polyetheramine is 1.4-1.8:0.2-0.6:1, and the total mass fraction of the solute is 0.7-2wt%.

4. The preparation method according to claim 2 or 3, characterized in that: In step 1, the first solvent is an ethanol / water mixed solvent, and the mass fraction of ethanol is 70-90wt%.

5. The preparation method according to claim 2 or 3, characterized in that: In step 1, the heating reaction temperature is 50-100° C. and the time is 2-4 hours.

6. The preparation method according to claim 2 or 3, characterized in that: In step 2, the UV / O3 treatment time is 90-150s, and the treatment temperature is 25-40 o C.

7. The preparation method according to claim 2 or 3, characterized in that: In step 3, the coating method is scraping, spin coating or spraying.

8. The preparation method according to claim 2 or 3, characterized in that: In step 3, the thermal cross-linking temperature is 60-100° C. and the time is 2 hours.

9. Use of the ultra-thin polyethylene oxide carbon capture membrane according to any one of claims 1 to 8 in separating CO2 / N2 mixed gases.

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