KR20230027901A - A mixed matrix membrane for gas separation, a gas separation membrane comprising the same, and a method for manufacturing the mixed matrix membrane - Google Patents

Abstract

The present invention relates to a mixed matrix membrane for gas separation, a gas separation membrane containing the same, and a method for manufacturing the mixed medium membrane. More specifically, the mixed matrix membrane of the present invention forms a selective layer on the surface of a porous polymer support, while being able to form a membrane with an ultra-thin asymmetric structure consisting of a porous layer, in which carbon dioxide can permeate very rapidly, at the upper end of the selective layer and a very thin dense layer, in which the selectivity of carbon dioxide can increase, at the lower end thereof by simultaneously satisfying the usage of a specific polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) copolymer and the excessive usage of a metal-organic framework. The mixed matrix membrane of the present invention can remarkably improve gas permeability and selectivity as compared with existing gas separation membranes by forming a very thin asymmetric structure without causing membrane defects due to the excellent interaction between the PVI-POEM copolymer and the metal-organic framework.

Description

A mixed matrix membrane for gas separation, a gas separation comprising membrane the same, and a method for manufacturing the mixed matrix membrane}

The present invention relates to a mixed medium separation membrane for gas separation, a gas separation membrane including the same, and a method for manufacturing the mixed medium separation membrane.

Among the gas separation membranes, especially for the separation of carbon dioxide, interest in the separation of carbon dioxide gas after combustion is increasing as the government's 2050 carbon neutral strategy is announced. In order to solve this problem, research is being conducted to utilize an energy-efficient gas separation membrane, which is advantageous in terms of process cost and does not accompany phase change in carbon dioxide separation thermodynamically. However, the still low carbon dioxide permeability and separation of gas separation membranes still remain a major limitation.

A polymer-based gas separation membrane utilizes the principle of gas permeation through a free volume of a polymer. However, gas separation membranes made of only polymers have limitations in permeability and have physical properties that make it difficult to form thin membranes. Therefore, a technology using a mixed-matrix membrane (MMM) that can simultaneously satisfy these requirements is required.

When a porous filler is added to the polymer matrix of the mixed medium separator, the passage through which carbon dioxide can permeate becomes wider, so that the permeability rapidly increases. However, in general, there is a problem in that a defect occurs at the interface, which causes a decrease in separation degree or provides a fundamental cause of poor film formation.

Therefore, it is necessary to research and develop a new separator material that can prevent interfacial defects of existing mixed media separators, have excellent gas permeability and selectivity, and can be well formed.

Korean Patent Registration No. 10-2225357

In order to solve the above problems, an object of the present invention is to provide a mixed medium separation membrane for gas separation in which a selective layer having an asymmetric structure is formed to significantly improve gas permeability and selectivity.

In addition, an object of the present invention is to provide a gas separation membrane including the mixed medium separation membrane.

Another object of the present invention is to provide a gas separation module including the gas separation membrane.

Another object of the present invention is to provide a gas separation device including the gas separation membrane.

Another object of the present invention is to provide a method for manufacturing a mixed medium separation membrane for gas separation.

The present invention is a porous polymer scaffold; and a selective layer formed on one or both surfaces of the porous polymer support, wherein the selective layer is polyvinylimidazole (PVI)-polyoxyethylene methacryl represented by Formula 1 below. a dense layer comprising a polymer matrix comprising a POEM copolymer and a first metal-organic framework (MOF); and a porous layer made of a second metal-organic framework while positioned on top of the dense layer.

[Formula 1]

(In Formula 1, x and y are the repeating numbers of each repeating unit, where x is 5 to 50, y is 50 to 120, x: y is 10:90 to 40:60, and n is 1 to 30 is an integer of .)

In addition, the present invention provides a gas separation membrane including the mixed medium separation membrane.

In addition, the present invention provides a gas separation module including the gas separation membrane.

In addition, the present invention provides a gas separation device including the gas separation membrane.

In addition, the present invention is polyvinylimidazole (PVI)-polyoxyethylene methacrylate represented by the following formula (1) by polymerizing polyoxyethylene methacrylate (POEM) with polyvinylimidazole (PVI) in the presence of an initiator. (POEM) preparing a copolymer; preparing a metal-organic framework (MOF) by mixing a metal precursor and an organic precursor; preparing a mixture by mixing the polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) copolymer and the metal organic framework in a solvent; forming a selective layer by coating the mixture on one or both surfaces of an upper portion of the porous polymer support; and drying the porous polymer support on which the selective layer is formed to prepare a mixed medium separation membrane for gas separation.

[Formula 1]

(In Formula 1, x and y are the repeating numbers of each repeating unit, where x is 5 to 50, y is 50 to 120, x: y is 10:90 to 40:60, and n is 1 to 30 is an integer of .)

The mixed medium separator according to the present invention forms a selective layer on the surface of a porous polymer support, but uses a specific polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) copolymer and metal-organic framework. By satisfying the excessive use at the same time, it is possible to form an ultra-thin, asymmetrical structure membrane composed of a porous layer through which carbon dioxide can permeate very quickly at the top of the selective layer and a very thin dense layer at the bottom where carbon dioxide selectivity can be increased.

The mixed medium separation membrane of the present invention has excellent gas permeability and selectivity compared to conventional gas separation membranes by forming a very thin asymmetric structure without causing membrane defects due to excellent interaction between the PVI-POEM copolymer and the metal-organic backbone. can be significantly improved.

The effects of the present invention are not limited to the effects mentioned above. It should be understood that the effects of the present invention include all effects that can be inferred from the following description.

1 is a schematic diagram of the synthesis of PVI-POEM copolymers synthesized in Examples 1 to 3 and Comparative Examples 1 to 4 of the present invention (a), FT-IR of PVI-POEM copolymers, ZIF-8 and PZ-x series Graph (b) and DSC graph (c) analysis results of the PVI-POEM copolymer and the PZ-x series are shown.
Figure 2 is a graph of XRD results (a), TGA result graph (b) and XPS of PVI-POEM copolymers, ZIF-8 and PZ-x series synthesized in Examples 1 to 3 and Comparative Examples 1 to 4 of the present invention These are the analysis result graphs (c, d, e).
3 is FE-SEM cross-sectional photographs (a to f) of the PZ-x-thin series (mixed medium separator) synthesized in Examples 4 to 6 and Comparative Examples 5 to 7 of the present invention and PZ-x-thin mixture It is a schematic diagram (g) schematically showing the manufacturing process of the medium separation membrane.
4 is FE-SEM cross-sectional photographs (a to f) of the PZ-x series (mixed medium separator) synthesized in Examples 1 to 3 and Comparative Examples 1 to 4 of the present invention. 4, FE-SEM cross-sectional images are (a) PZ-10, (b) PZ-20, (c) PZ-30, (d) PZ-40, (e) PZ-50, (f) PZ showed -60.
Figure 5 is a pure PVI-POEM polymer membrane (a), AFM for the PZ-x series (mixed media separator) synthesized in Comparative Example 1 (b), Example 1 (c) and Example 2 (d) of the present invention This is a picture of the result.
6 shows the pure PVI-POEM polymer separator of the present invention and the PZ-x series (mixed medium separator) synthesized in Examples 1 to 3 and Comparative Examples 1 to 4 (a) having i) high permeability and ii) low permeability CO ₂ /CH ₄ separation performance graph using a support (PZ-x series), (b) the pure PVI-POEM-thin polymer membrane and the PZ-x-thin synthesized in Examples 4 to 6 and Comparative Examples 6 to 8 CO ₂ /CH ₄ separation performance graph of the series, (c) CO ₂ /N ₂ separation performance graph of the PZ-x-thin series, (d) stability over time of Example 5 (PZ-50-thin) above (stability) It shows the measurement graph.
7 shows ZIF-8 and PVI-POEM for gas separation membranes using the PZ-x series (mixed medium separation membrane) synthesized in Examples 1 to 3 (d, c, b) and Comparative Example 4 (a) of the present invention. This is a graph comparing the distance of the polymer to the ZIF-8 surface according to the ratio.
8 shows the gas separation membrane using the PZ-x series (mixed medium separation membrane) synthesized in Examples 1 to 3 and Comparative Example 4 of the present invention, with a mixing ratio of ZIF-8:PVI-POEM of (a) 80:20 (Comparative Example 4), (b) 60:40 (Example 3), (c) 50:50 (Example 2) and (d) 40:60 (Example 1) according to the free volume (free volume) It is the result of calculating volume) and porosity.
9 is a graph of (a, b) CO ₂ , (c, d) CH ₄ , ( e, f) energy profile graphs between N ₂ and PZ-x series and (g) CO ₂ /CH ₄ and (h) CO ₂ /N ₂ relative interaction energy plots.

Hereinafter, the present invention will be described in more detail as an embodiment.

The present invention relates to a mixed medium separation membrane for gas separation, a gas separation membrane including the same, and a method for manufacturing the mixed medium separation membrane.

As described above, the conventional mixed-medium separation membrane increases gas permeability by mixing a porous filler with a polymer matrix, but defects occur at the interface, which causes a decrease in separation degree or the membrane is not properly formed.

Therefore, in the present invention, a selective layer is formed on the surface of the porous polymer support, but the use of a specific polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) copolymer and excessive use of a metal-organic framework are avoided. At the same time, it is possible to manufacture a mixed medium separation membrane for gas separation in which an asymmetric structure consisting of a porous layer through which carbon dioxide can permeate very quickly at the top of the selective layer and a very thin and dense layer at the bottom of the selective layer can increase the selectivity of carbon dioxide. could

The mixed medium separation membrane of the present invention has excellent gas permeability and selectivity compared to conventional gas separation membranes by forming a very thin asymmetric structure without causing membrane defects due to excellent interaction between the PVI-POEM copolymer and the metal-organic backbone. can be significantly improved.

Specifically, the present invention is a porous polymer support; and a selective layer formed on one or both surfaces of the porous polymer support, wherein the selective layer is polyvinylimidazole (PVI)-polyoxyethylene methacryl represented by Formula 1 below. a dense layer comprising a polymer matrix comprising a POEM copolymer and a first metal-organic framework (MOF); and a porous layer made of a second metal-organic framework while positioned on top of the dense layer.

[Formula 1]

(In Formula 1, x and y are the repeating numbers of each repeating unit, where x is 5 to 50, y is 50 to 120, x: y is 10:90 to 40:60, and n is 1 to 30 Preferably, x and y are the repeating numbers of each repeating unit, where x is 15 to 40, y is 60 to 90, x:y is 25:75 to 35:65, and n is 5 to It is an integer of 12.)

The porous polymer support is polysulfone, polyestersulfone, polymethyl methacrylate, polyethylene, polypropylene, polyoxymethylene, polyether ether ketone, polyethylene terephthalate, polyacrylonitrile, cellulose acetate, polyamide, polyimide, It may be at least one selected from the group consisting of polyamideimide, polyetherimide, polyvinylidene fluoride, polyvinyl alcohol, and polyarylate. Preferably, it may be at least one selected from the group consisting of polysulfone, polyestersulfone, and polyacrylonitrile, and most preferably, it may be polysulfone. The polysulfone is inexpensive compared to other porous polymer scaffolds and has excellent gas permeability due to its high porosity.

The porous polymer support may have a gas permeability of 5000 to 500000 GPU.

The porous polymer support may further include a surface coating layer coated with poly(1-trimethylsilyl-1-propyne). The surface coating layer is formed by coating a polymer having excellent gas permeability on the surface of the porous polymer support, and may be formed to prevent interface defects and increase interaction with the selective layer.

The polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) copolymer is a polymer with very high solubility in water and ethanol, and has a polyethylene glycol group and an imidazoling group that have a very good interaction with carbon dioxide. When mixed with a metal-organic framework, it has excellent dispersibility and interfacial contact ability due to its high chemical similarity, and it is possible to form a defect-free, very thin and dense polymer matrix film with almost no interfacial defects due to its rubber-like properties.

In general, conventional separators may not form well when 30% by weight or more of metal organic framework is mixed, but in the present invention, a material having a very good interaction between the polymer matrix and the metal organic framework is selectively used, Gas separation performance can be improved by forming a film having an asymmetric structure without defects by mixing the metal organic framework. The first and second metal organic frameworks are present in an amount of 35 to 65% by weight, preferably 40 to 60% by weight, more preferably 40 to 50% by weight, and most preferably 50% by weight, based on 100% by weight of the selective layer. % may be included.

In this case, when the content of the first and second metal organic frameworks is less than 35% by weight, the selective layer does not form an asymmetric structure composed of a dense layer and a porous layer, and thus improved gas separation performance cannot be expected. Conversely, if the content exceeds 65% by weight, the selective layer may form an excessively asymmetrical structure, resulting in excellent gas permeability but relatively low gas selectivity.

The first and second metal organic frameworks have a porous and uniform pore structure, and may preferably be Zn-based zeolitic imidazole frameworks (ZIF). Specific examples of the Zn-based zeolite imidazole framework may be one or more selected from the group consisting of ZIF-7, ZIF-8, ZIF-22, ZIF-90, ZIF-8-90 and ZIF-7-8, Preferably it may be ZIF-8. The Zn-based zeolite imidazole framework has excellent solvent dispersibility in water and ethanol and excellent interaction with the PVI-POEM copolymer, so it can be applied to gas separation membranes.

The zinc (Zn) content of the Zn-based zeolite imidazole framework is 4 to 10 atomic %, preferably 5 to 8 atomic %, and most preferably 5.7 to 6.4 atomic % based on the total number of atoms included in the selective layer. % may be included. At this time, if the zinc content is less than 4 atomic %, the mechanical strength and durability of the mixed medium separation membrane may be lowered and the membrane may be easily torn. can

The selective layer may have an asymmetric structure composed of a dense layer having a thickness of 0.01 to 1 μm, preferably 0.05 to 0.5 μm, and a porous layer having a thickness of 0.1 to 5 μm, preferably 0.2 to 2 μm. The dense layer includes a polymer matrix including the PVI-POEM copolymer having carbon dioxide-friendly properties and a first metal-organic framework, so that carbon dioxide selectivity can be improved. The porous layer is located on top of the dense layer and is composed of a second metal-organic skeleton, so it can serve as a passage through which all gases can pass very quickly, and thus have a very high gas permeability compared to other existing gas separation membranes. can have

In the case of a general gas separation membrane, it is composed of a thick layer of several micrometers, and since the gas permeability decreases as the thickness increases, it is important to increase the gas permeability of the membrane itself. Accordingly, when a specific polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) copolymer is not used as the selective layer or an excessive amount of metal-organic framework is not mixed, a dense layer having an asymmetric structure and A selective layer including a porous layer cannot be formed, and gas selectivity can be maintained at the same level as conventional gas separation membranes, but overall gas separation performance can be deteriorated due to low gas permeability.

As a result of AFM analysis, the selective layer may have a surface roughness factor (Rq) of 70 to 85 nm, preferably 75.7 to 79.1 nm, and a porosity of 54 to 71%.

The gas may be at least one selected from carbon dioxide, nitrogen and methane.

As described above, the mixed medium separation membrane for gas separation of the present invention simultaneously satisfies the use of a specific polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) copolymer and the excessive use of a metal-organic framework. By doing so, a selective layer composed of an asymmetric structure of a dense layer capable of effectively separating carbon dioxide and a porous layer having excellent carbon dioxide permeability is formed on the porous polymer support, thereby significantly improving gas permeability and selectivity of the membrane itself.

Meanwhile, the present invention provides a gas separation membrane including the mixed medium separation membrane.

The gas separation membrane may have a carbon dioxide (CO ₂ ) permeability of 2058 GPU or more, a carbon dioxide/nitrogen (CO ₂ /N ₂ ) selectivity of 22.1 or more, and a carbon dioxide/methane (CO ₂ /CH ₄ ) selectivity of 9.7 or more. .

In addition, the present invention provides a gas separation module including the gas separation membrane.

In addition, the present invention provides a gas separation device including the gas separation membrane.

In addition, the present invention is polyvinylimidazole (PVI)-polyoxyethylene methacrylate represented by the following formula (1) by polymerizing polyoxyethylene methacrylate (POEM) with polyvinylimidazole (PVI) in the presence of an initiator. Preparing a POEM copolymer; preparing a metal-organic framework (MOF) by mixing a metal precursor and an organic precursor; preparing a mixture by mixing the polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) copolymer and the metal organic framework in a solvent; forming a selective layer by coating the mixture on one or both surfaces of an upper portion of the porous polymer support; and drying the porous polymer support on which the selective layer is formed to prepare a mixed medium separation membrane for gas separation.

[Formula 1]

(In Formula 1, x and y are the repeating numbers of each repeating unit, where x is 5 to 50, y is 50 to 120, x: y is 10:90 to 40:60, and n is 1 to 30 Preferably, x and y are the repeating numbers of each repeating unit, where x is 15 to 40, y is 60 to 90, x:y is 25:75 to 35:65, and n is 5 to It is an integer of 12.)

In preparing the copolymer, the polyvinylimidazole (PVI) and polyoxyethylene methacrylate (POEM) are mixed in a weight ratio of 10:90 to 40:60, preferably in a weight ratio of 25:75 to 35:65, the most Preferably, they may be mixed in a weight ratio of 30:70.

The initiator is present in an amount of 0.01 to 1 part by weight, preferably 0.05 to 0.5 part by weight, most preferably 0.2 part by weight, based on 100 parts by weight of the mixed solution of polyvinylimidazole (PVI) and polyoxyethylene methacrylate (POEM). Parts by weight can be mixed. At this time, if the content of the initiator is less than 0.01 parts by weight, radical polymerization may not occur properly, and conversely, if it exceeds 1 part by weight, gas separation performance and mechanical properties may be deteriorated due to excessive radical polymerization.

The initiator may be at least one selected from the group consisting of azobisisobutyronitrile (AIBN), ammonium persulfate, and hydroperoxide, preferably azobisisobutyronitrile. there is.

In the step of preparing the metal organic framework, the metal precursor may be at least one selected from the group consisting of zinc, titanium, iron, zirconium, copper, aluminum, chromium, gallium, magnesium and manganese, preferably zinc and iron. , It may be at least one selected from the group consisting of copper, magnesium and manganese, more preferably at least one selected from the group consisting of zinc, iron and copper, and most preferably zinc.

Specific examples of the zinc precursor include the group consisting of Zn(NO ₃ ) ₂ 6H ₂ O, Zn(NO ₃ ) ₃ 9H ₂ O, ZnCl ₂ , ZnSO ₄ , Zn(OH) ₂ and Zn(CH ₃ CO ₂ ) ₂ It may be one or more selected from. Preferably, it may be Zn(NO ₃ ) ₂ 6H ₂ O, Zn(NO ₃ ) ₃ 9H ₂ O, or a mixture thereof, and most preferably Zn(NO ₃ ) ₂ 6H ₂ O.

The organic precursor is 2-methylimidazole, imidazole, 1-ethylimidazole, 2-nitroimidazole, 4-methyl-5 -Imidazole carboxaldehyde (4-methyl-5-imidazolecarboxaldehyde), 5-nitro-1H-benzimidazole, 4-formylimidazole, purin , (1H-imidazol-2-yl)methanol ((1H-imidazol-2-yl)methanol) and 5-chlorobenzimidazole (5-chlorobenzimidazole) may be at least one selected from the group consisting of. Preferably, it may be at least one selected from the group consisting of 2-methylimidazole, imidazole, and 1-ethylimidazole, and most preferably 2-methylimidazole.

The metal organic framework may be mixed in an amount of 35 to 65% by weight, preferably 40 to 60% by weight, more preferably 40 to 50% by weight, and most preferably 50% by weight, based on 100% by weight of the mixture. .

The solvent may be at least one selected from the group consisting of water, methanol, ethanol, propanol, butanol, isopropanol, tetrahydrofuran, ethyl acetate, chloroform, dimethyl sulfoxide, dimethylformamide, and N-methyl-2-pyrrolidone. there is. Preferably, it may be a mixed solvent in which ethanol and water are mixed in a weight ratio of 7:3.

Before forming the selective layer, forming a surface coating layer using poly(1-trimethylsilyl-1-propyne) on the surface of the porous polymer support may be further included.

In the forming of the selective layer, the mixture may be coated on the surface of the porous polymer support by a bar coating method.

In the step of forming the optional layer, the coating amount of the optional layer may be 2 to 10% by weight, preferably 2.2 to 7% by weight, more preferably 2.5 to 5% by weight, and most preferably 2.7 to 3% by weight. there is. At this time, if the coating amount of the selective layer is less than 2% by weight, the thickness of the selective layer may be too thin and the gas permeability and selectivity may be lowered. can be significantly lowered.

In the step of forming the selection layer, the selection layer is composed of a dense layer having a thickness of 0.01 to 1 μm, preferably 0.05 to 0.5 μm, and a porous layer having a thickness of 0.1 to 5 μm, preferably 0.2 to 2 μm. structure can be formed.

The dense layer includes a polymer matrix including the polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) copolymer and a first metal-organic framework (MOF), The porous layer may be formed of a second metal-organic framework while being positioned on top of the dense layer.

In the step of preparing the mixed medium separation membrane for gas separation, drying may be performed at a temperature of 20 to 30 °C for 4 to 8 hours, preferably at a temperature of 23 to 27 °C for 5 to 7 hours. At this time, if both the drying temperature and time conditions are not satisfied, an even and uniform thin selective layer may not be properly formed on the porous polymer support.

In particular, although not explicitly described in the following Examples or Comparative Examples, in the method for manufacturing a mixed medium separation membrane for gas separation according to the present invention, the mixed medium separation membrane prepared by varying the following 13 conditions is applied to the gas separation membrane An additional experiment was conducted to measure the carbon dioxide permeability and selectivity for 600 hours under the same conditions as in Experimental Example 5 to be described later, mechanical stiffness and durability of the membrane, by a conventional method.

As a result, it was confirmed that the mixed medium separation membrane of the present invention has remarkably excellent mechanical stiffness and durability due to containing an excessive amount of the metal-organic framework, and the carbon dioxide permeability and selectivity are maintained at high levels for a long time of 600 hours. confirmed that

① the porous polymer support is polysulfone, ② before forming the selective layer, forming a surface coating layer on the surface of the porous polymer support using poly(1-trimethylsilyl-1-propyne); Further comprising, ③ preparing the copolymer is mixing the polyvinylimidazole (PVI) and polyoxyethylene methacrylate (POEM) in a weight ratio of 25:75 to 35:65, ④ the initiator is azo arsenic butyronitrile (azobisisobutyronitrile, AIBN), and (5) in Formula 1, x and y are the repeating numbers of each repeating unit, x is 15 to 40, y is 60 to 90, and x:y is 25:75 to 35:65, n is an integer from 5 to 12, ⑥ the metal organic framework contains 40 to 50% by weight with respect to 100% by weight of the mixture, ⑦ the metal organic framework is ZIF-8, ⑧ The zinc (Zn) content of the ZIF-8 includes 5.7 to 6.4 atomic % based on the total number of atoms included in the optional layer, ⑨ the solvent is a mixed solvent of ethanol and water, ⑩ the coating amount of the optional layer is 2.7 to 3% by weight, ⑪ the selective layer has an asymmetric structure consisting of a dense layer having a thickness of 0.05 to 0.5 μm and a porous layer having a thickness of 0.2 to 2 μm, and ⑫ the selective layer has a surface as a result of AFM analysis The roughness factor (Rq) is 75.7 to 79.1 nm, the porosity is 54 to 71%, and ⑬ in the step of preparing the mixed medium separation membrane for gas separation, drying is performed at a temperature of 23 to 27 ° C. to 7 hours.

However, when any one of the 13 conditions was not satisfied, the mechanical strength and durability of the membrane were relatively low, and the carbon dioxide selectivity was generally excellent, but the carbon dioxide permeability was significantly reduced. After 300 hours, the carbon dioxide selectivity and It was confirmed that the permeability dropped rapidly.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by the following examples.

Examples 1 to 3 and Comparative Examples 1 to 4

(1) Preparation of PVI-POEM copolymer

[Scheme 1]

(In Scheme 1 above, x is 30 and y is 70.)

A mixed solution was prepared by mixing 3 g of VI (1-vinylimidazole) and 7 g of POEM (poly (oxyethylene methacrylate)) in 35 mL of ethanol. In addition, 0.02 g of AIBN initiator was separately dissolved in 2 mL of DMF. Then, a reactant was prepared by mixing 0.2 parts by weight of the AIBN initiator solution with 100 parts by weight of the mixed solution, and then purged with nitrogen gas for 1 hour. At this time, the purging means a process of filling the gas inside the flask with nitrogen. The reactants were then polymerized at 70 °C for 24 hours. Then, the reaction product after polymerization was precipitated in an excess (> 300 mL) of n-hexane, washed, put in a vacuum oven at 50 ° C., and dried for 24 hours to prepare a PVI-POEM copolymer.

(2) Preparation of ZIF-8

A zinc precursor solution was prepared by dissolving 2.9 g of Zn(NO ₃ ) ₂ 6H ₂ O in 100 mL of methanol, and 6.9 g of 2-methylimidazole (2MIm) was dissolved in 100 mL of methanol to obtain 2- An aqueous solution of methylimidazole was prepared. Then, the zinc precursor solution and the 2-methylimidazole aqueous solution were subjected to magnetic stirring at room temperature for 3 hours, and then centrifuged at 9000 rpm for 20 minutes to obtain a precipitated reactant. The reactants were dried for 24 hours under vacuum conditions at 50 °C. Subsequently, ZIF-8 was obtained by activation (activation) for 24 hours under vacuum conditions at 180 ° C. to dry the residual solvent.

(3) Preparation of PVI-POEM/ZIF-8 Mixed Media Membrane (MMMs)

The PVI-POEM copolymer and ZIF-8 were added to the mixed solvent (ethanol/water = 7:3 weight ratio) at the mixing ratio shown in Table 1 below, and mixed for 1 hour to prepare a mixture of 5% by weight based on mass ratio. A solution in which 1.5% by weight of PTMSP was dissolved in cyclohexane was coated on the surface of a polysulfone (PSf) support to form a gutter layer. Then, 5% by weight of the mixture was coated on the gutter layer on the surface of the polysulfone support by a bar-coating technique, and then dried in a vacuum oven at 25 ° C. for 6 hours to form an asymmetric structure of a dense layer and a porous layer. A PVI-POEM/ZIF-8 mixed media separator having a selective layer of was prepared. At this time, the thickness of the formed selective layer was 0.25 μm, the dense layer had a thickness of 0.05 μm and included PVI-POEM copolymer and ZIF-8, and the porous layer had a thickness of 0.2 μm and was made of ZIF-8 . The PVI-POEM/ZIF-8 mixed media separators were named as PZ-x series (where x is the loading amount of ZIF-8) as shown in Table 1 below.

Examples 4 to 6 and Comparative Examples 5 to 8

A PZ-x-thin series was prepared in the same manner as in Example 1, except that 2.7% by weight of the mixture was bar-coated on the gutter layer of the surface of the polysulfone support of Example 1. At this time, the thickness of the selective layer of each PZ-x-thin series was 0.25 μm, the dense layer had a thickness of 0.05 μm, and the porous layer had a thickness of 0.2 μm, forming thinner films. The PZ-x-thin series is PZ-10-thin (Comparative Example 5), PZ-20-thin (Comparative Example 6), PZ-30-thin (Comparative Example 7), PZ-40-thin (Example 4 ), PZ-50-thin (Example 5), PZ-60-thin (Example 6), and PZ-70-thin (Comparative Example 8).

Experimental Example 1: FT-IR and DSC analysis

FT-IR analysis and differential scanning calorimetry (Differential Scanning Calorimetry, DSC) was used to analyze the structure and glass transition temperature of each product. The results are shown in Figure 1.

1 is a schematic diagram of the synthesis of PVI-POEM copolymers synthesized in Examples 1 to 3 and Comparative Examples 1 to 4 (a), FT-IR graphs of PVI-POEM copolymers, ZIF-8 and PZ-x series ( b) and DSC graph (c) analysis results of the PVI-POEM copolymer and the PZ-x series.

Referring to (a) of FIG. 1, a process of synthesizing a PVI-POEM copolymer by synthesizing POEM with a PEG group and VI with an imidazole ring by free radical polymerization is shown.

Referring to (b) of FIG. 1, it was confirmed that the PVI-POEM copolymer simultaneously contained C-O of PEG and C-N of imidazole. On the other hand, in the case of the PZ-x series, uniquely, as ZIF-8 is added, the C-N band of the imidazole ring present only in PVI, which is not present in the 2-methylimidazole ring of ZIF-8 The band intensity tended to increase relatively, which means that the interaction between the PVI-POEM copolymer and the metal-organic framework was very good. In addition, it was confirmed that the bands visible only in the ZIF-8 gradually increased according to the content of ZIF-8.

In addition, referring to (c) of FIG. 1, unlike the general mixed media separator (MMM), the glass transition temperature (Tg) gradually decreases as the amount of ZIF-8 added decreases, which is It was found that the coalescence itself was in a gel state rather than a complete solid state, and the self-interaction was good. In addition, it was conjectured that the permeability could be further increased by increasing the free volume.

Experimental Example 2: XRD, TGA and XPS analysis

For the PVI-POEM copolymers, ZIF-8 and PZ-x series (mixed medium separators) synthesized in Examples 1 to 3 and Comparative Examples 1 to 4, the composition of each result was analyzed using XRD, TGA and XPS analysis. analyzed. The results are shown in Figure 2 and Table 2.

Figure 2 is a graph of XRD results (a), a graph of TGA results (b) and XPS analysis results of the PVI-POEM copolymers, ZIF-8 and PZ-x series synthesized in Examples 1 to 3 and Comparative Examples 1 to 4 These are the graphs (c, d, e).

Referring to (a) and (b) of FIG. 2, it was confirmed that the crystallinity of ZIF-8 increased as the addition amount of ZIF-8 increased, and the residual amount remained after 800 ° C. Through this, it was found that the ZIF-8 had a very high crystallinity and exhibited a porous pore structure due to remaining carbons after being carbonized at a high temperature.

In addition, referring to (c, d, e) of FIG. 2, the PVI-POEM copolymer was able to confirm all of the C-C, C-N, and C=N bonds of the copolymer itself, and in the PZ-x series, the peak intensity (peak intensity) was confirmed to be relatively low. In particular, it was confirmed that the binding energy of C-O significantly changed as the addition amount of ZIF-8 increased in the O 1s region. It was found that the intensity of C-O is changed by the ZIF-8, that is, an interaction exists. The atomic ratio of each element derived from the XPS result graph is shown in Table 2 below.

Referring to Table 2, it was confirmed that the amount of Zn gradually increased proportionally as the addition amount of ZIF-8 increased.

Experimental Example 3-1: FE-SEM analysis

FE-SEM analysis was performed to confirm the cross-sectional structure of the PZ-x-thin series (mixed medium separator) synthesized in Examples 4 to 6 and Comparative Examples 5 to 7. The results are shown in Figure 3.

3 is FE-SEM cross-section photographs (a to f) of the PZ-x-thin series (mixed medium separator) synthesized in Examples 4 to 6 and Comparative Examples 5 to 7 and PZ-x-thin mixed medium separators. It is a schematic diagram (g) schematically showing the manufacturing process of. In FIG. 3, FE-SEM cross-sectional images are (a) PZ-10-thin (Comparative Example 5), (b) PZ-20-thin (Comparative Example 6), and (c) PZ-30-thin (Comparative Example), respectively. 7), (d) PZ-40-thin (Example 4), (e) PZ-50-thin (Example 5), and (f) PZ-60-thin (Example 6).

Looking at (a) to (f) of FIG. 3, it was confirmed that the PZ-x-thin series can manufacture a very thin mixed medium separator having a total thickness of about 500 nm or less after forming a selective layer. In addition, it was found that the selective layer could successfully form a film without permeating into the polysulfone support.

In addition, (g) of FIG. 3 shows that when the loading amount of ZIF-8 is as low as 30% by weight or less, a typical mixed medium separator structure is formed and a relatively thin separator film is formed. On the other hand, when the loading amount of the ZIF-8 is higher than 30% by weight, a very thin dense layer on a porous polymer support and a relatively thick porous layer thereon show an asymmetric selective layer. It was found that the asymmetric structure of the selective layer allows all gases to permeate very quickly through the pores of the porous layer, and only carbon dioxide can be selectively separated while passing through the dense layer.

Experimental Example 3-2: FE-SEM analysis

FE-SEM analysis was performed to confirm the cross-sectional structure of the PZ-x series (mixed medium separator) synthesized in Examples 1 to 3 and Comparative Examples 1 to 4. The results are shown in FIG. 4 .

4 is FE-SEM cross-sectional photographs (a to f) of the PZ-x series (mixed medium separator) synthesized in Examples 1 to 3 and Comparative Examples 1 to 4. 4, FE-SEM cross-sectional images are (a) PZ-10, (b) PZ-20, (c) PZ-30, (d) PZ-40, (e) PZ-50, (f) PZ showed -60.

Referring to FIG. 4, it was confirmed that the PZ-x series had a thicker selection layer compared to the PZ-x-thin series of FIG. 3 and exhibited a clear asymmetric structure. As in the PZ-x-thin series, it was confirmed that the top of the selective layer was composed of a porous layer, forming a structure through which gas could pass very quickly, and a very thin dense layer was formed at the bottom. Through this, it was found that gas can permeate quickly and at the same time, separation occurs only in a very thin membrane to achieve high permeability and considerable selectivity.

Experimental Example 4: AFM analysis

AFM analysis was performed to confirm the cross-sectional structure of the PZ-x series (mixed medium separator) and the pure PVI-POEM polymer membrane synthesized in Examples 1 to 3 and Comparative Example 1. The results are shown in FIG. 5 .

5 is a photograph of the AFM results for the PZ-x series (mixed media separator) synthesized in pure PVI-POEM polymer membrane (a), Comparative Example 1 (b), Example 1 (c) and Example 2 (d) . Referring to (a) of FIG. 5, in the case of the PVI-POEM polymer separator, the surface was smooth and the roughness factor (Rq) was measured to be very low. On the other hand, in the case of Comparative Example 1 (PZ-10), Rq increased very much, and in Example 1 (PZ-40) and Example 2 (PZ-50) having asymmetry, 10), but still high Rq values were measured because of the porous surface. This was a structural feature indicating that the mixed medium separator was well formed.

Experimental Example 5: Gas Permeability and Selectivity Analysis of Gas Separation Membrane

The PZ-x series, PZ-x-thin series (mixed medium separation membrane) and the pure PVI-POEM polymer membrane synthesized in Examples 1 to 6 and Comparative Examples 1 to 7 were applied as gas separation membranes to produce gas permeation devices and flow meters. Separation performance of gas permeability and selectivity was confirmed by using. In addition, gas permeation performance was analyzed using a support having a high permeability of 11300 GPU and a support having a low permeability of 6200 GPU for the polysulfone support. The results are shown in Figure 6 and Table 3.

FIG. 6 shows support materials having (a) high permeability and ii) low permeability for the pure PVI-POEM polymer separator and the PZ-x series (mixed medium separator) synthesized in Examples 1 to 3 and Comparative Examples 1 to 4 CO ₂ /CH ₄ separation performance graph (PZ-x series), (b) of the pure PVI-POEM-thin polymer membrane and the PZ-x-thin series synthesized in Examples 4 to 6 and Comparative Examples 6 to 8 CO ₂ /CH ₄ separation performance graph, (c) CO ₂ /N ₂ separation performance graph of the PZ-x-thin series, (d) stability over time of Example 5 (PZ-50-thin) ) shows the measurement graph.

Referring to FIG. 6 (a), as a result of analyzing how much the permeability of the polysulfone support affects the performance of the actual PZ-x separation membrane, the higher the permeability of the support, the higher the permeability of the entire membrane. Confirmed. In general, there are many results in which the permeability of the support is not related to the actual separation membrane. From the above results, it can be seen that the permeability of the membrane is improved by manufacturing an extremely thin separation membrane.

In addition, referring to (b) and (c) of FIG. 6, in the case of the PZ-x-thin series prepared to achieve higher permeability, both the CO ₂ /N ₂ permeability and the CO ₂ /CH ₄ permeability are burned. A high transmittance far exceeding that of the post-combustion target was achieved.

Table 3 below shows the results of evaluating the gas separation performance of the PZ-x series and the PZ-x-thin series and other conventional gas separation membranes.

According to the results of Table 3, in the case of Examples 1 to 6, compared to Comparative Examples 1 to 8, not only the gas permeability to carbon dioxide, nitrogen and methane was significantly improved, but also the selectivity for carbon dioxide among these gases It was confirmed that it showed excellent figures. In particular, in the case of Examples 4 to 6, it was confirmed that the ultra-thin film type and the asymmetric structure exhibited the best gas permeability and selectivity performance.

On the other hand, in the case of Comparative Examples 1 to 8, the carbon dioxide permeability was generally high, but the content of ZIF-8 was low, so it was confirmed that the selective layer did not form an asymmetric membrane, so the gas permeability was very low. In addition, in the case of the conventional gas separation membrane, the carbon dioxide selectivity showed the best values, but the gas permeability showed a remarkably low value.

Experimental Example 6: Gas Permeability and Selectivity Analysis of Gas Separation Membrane

Molecular dynamics simulation to confirm why high selectivity can be achieved without defects for the gas separation membrane using the PZ-x series (mixed media membrane) synthesized in Examples 1 to 3 and Comparative Example 4 analysis was performed. The results are shown in Figures 7 to 9.

7 shows the ratio of ZIF-8 and PVI-POEM for gas separation membranes using the PZ-x series (mixed medium membrane) synthesized in Examples 1 to 3 (d, c, b) and Comparative Example 4 (a). This is a graph comparing the distance of the polymer to the ZIF-8 surface according to Referring to FIG. 7, it was confirmed that as the content of the PVI-POEM copolymer decreased, the distance between polymer chains on the surface of ZIF-8 decreased and defects disappeared. Here, the y-axis of the graph means the distance between the polymers on the surface of ZIF-8.

8 shows a gas separation membrane using the PZ-x series (mixed medium separation membrane) synthesized in Examples 1 to 3 and Comparative Example 4 at a mixing ratio of ZIF-8:PVI-POEM of (a) 80:20 (comparison) Example 4), (b) 60:40 (Example 3), (c) 50:50 (Example 2) and (d) 40:60 (Example 1) free volume according to the composition ratio is the result of calculating the porosity. Referring to FIG. 8, as a result of calculating the porosity, it was confirmed that the porosity rather decreased according to the content of the ZIF-8, which is due to the disappearance of defects between the PVI-POEM copolymer and ZIF-8. It was found that the factor led to the decrease in porosity.

9 shows (a, b) CO ₂ , (c, d) CH ₄ , (e, f) An energy profile graph between N ₂ and PZ-x series and (g) CO ₂ /CH ₄ and (h) CO ₂ /N ₂ relative interaction energy plot graphs are shown.

Referring to FIG. 9, as a result of calculating the relative interaction energies of CO ₂ , CH ₄ and N _{2 ,} Example 2 (ZIF-8:PVI-POEM= 50:50) and Example 3 (ZIF-8: PVI-POEM = 60:40) was confirmed to exhibit a very high carbon dioxide interaction, and through this, it was found to show high gas permeability and selectivity.

As described above, the mixed medium separator prepared in Examples 1 to 6 of the present invention has very excellent interfacial interaction between the PVI-POEM copolymer and ZIF-8, so that a selective layer without defects can be formed, and the asymmetric structure Due to this, it was confirmed that carbon dioxide permeated very quickly and significantly high carbon dioxide selectivity and permeability could be maintained. That is, because of the asymmetric structure, CO ₂ permeance dramatically increased, achieving very high performance far exceeding the CO ₂ combustion target area (> 2000 GPU, 20 CO ₂ /N ₂ selectivity). . In particular, in the case of Example 5 (PZ-50-thin), the CO ₂ permeability was 4474 GPU, the CO ₂ /N ₂ selectivity was 32.0, and the CO ₂ /CH ₄ selectivity was 12.4, thereby achieving the best gas permeability and Selectivity was shown.

Claims (24)

porous polymer support; and a selective layer formed on one or both surfaces of the porous polymer support. A mixed medium separation membrane for gas separation comprising:
The optional layer is a polymer matrix including a polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) copolymer represented by Formula 1 below and a first metal-organic framework (MOF). ) Dense layer comprising; and
A mixed medium separation membrane for gas separation comprising: a porous layer made of a second metal-organic framework and positioned on top of the dense layer.
[Formula 1]

(In Formula 1 above,
x and y are the repeating numbers of each repeating unit, x is 5 to 50, y is 50 to 120, x:y is 10:90 to 40:60,
n is an integer from 1 to 30.)
According to claim 1,
The porous polymer support is polysulfone, polyestersulfone, polymethyl methacrylate, polyethylene, polypropylene, polyoxymethylene, polyether ether ketone, polyethylene terephthalate, polyacrylonitrile, cellulose acetate, polyamide, polyimide, A mixed medium separation membrane for gas separation, which is at least one selected from the group consisting of polyamideimide, polyetherimide, polyvinylidene fluoride, polyvinyl alcohol, and polyarylate.
According to claim 1,
The porous polymer support further comprises a surface coating layer coated with poly (1-trimethylsilyl-1-propyne) on the surface of the mixed medium separation membrane for gas separation.
According to claim 1,
In Formula 1, x and y are the repeating numbers of each repeating unit, x is 15 to 40, y is 60 to 90, x: y is 25:75 to 35:65, and n is an integer of 5 to 12 A mixed medium separation membrane for gas separation.
According to claim 1,
The mixed medium separation membrane for gas separation, wherein the first and second metal organic frameworks contain 35 to 65% by weight based on 100% by weight of the selective layer.
According to claim 1,
Wherein the first and second metal-organic frameworks are Zn-based zeolitic imidazole frameworks (ZIF), a mixed medium separation membrane for gas separation.
According to claim 6,
The Zn-based zeolite imidazole skeleton is at least one selected from the group consisting of ZIF-7, ZIF-8, ZIF-22, ZIF-90, ZIF-8-90 and ZIF-7-8. medium separator.
According to claim 6,
The mixed medium separation membrane for gas separation, wherein the zinc (Zn) content of the Zn-based zeolite imidazole framework comprises 4 to 10 atomic% based on the total number of atoms included in the selective layer.
According to claim 1,
The mixed medium separation membrane for gas separation, wherein the selective layer has an asymmetric structure composed of a dense layer having a thickness of 0.01 to 1 μm and a porous layer having a thickness of 0.1 to 5 μm.
According to claim 1,
The selective layer has a surface roughness factor (Rq) of 70 to 85 nm and a porosity of 54 to 71% as a result of AFM analysis.
According to claim 1,
The mixed medium separation membrane for gas separation, wherein the gas is at least one selected from carbon dioxide, nitrogen, and methane.
A gas separation membrane comprising the mixed medium separation membrane according to any one of claims 1 to 11.
According to claim 12,
The gas separation membrane has a carbon dioxide (CO ₂ ) permeability of 2058 GPU or more, a carbon dioxide / nitrogen (CO ₂ / N ₂ ) selectivity of 22.1 or more, and a carbon dioxide / methane (CO ₂ / CH ₄ ) selectivity of 9.7 or more. gas separation membrane.
A gas separation module comprising the gas separation membrane of claim 12.
A gas separation device comprising the gas separation membrane of claim 12.
Polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) represented by Formula 1 is obtained by polymerizing polyoxyethylene methacrylate (POEM) with polyvinylimidazole (PVI) in the presence of an initiator. Preparing a coalescence;
preparing a metal-organic framework (MOF) by mixing a metal precursor and an organic precursor;
preparing a mixture by mixing the polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) copolymer and the metal organic framework in a solvent;
forming a selective layer by coating the mixture on one or both surfaces of an upper portion of the porous polymer support; and
drying the porous polymer support on which the selective layer is formed to prepare a mixed medium separation membrane for gas separation;
Method for producing a mixed medium separation membrane for gas separation comprising a.
[Formula 1]

(In Formula 1 above,
x and y are the repeating numbers of each repeating unit, x is 5 to 50, y is 50 to 120, x:y is 10:90 to 40:60,
n is an integer from 1 to 30.)
According to claim 16,
The method of manufacturing a mixed medium separation membrane for gas separation, wherein the metal organic framework is mixed in an amount of 35 to 65% by weight based on 100% by weight of the mixture.
According to claim 16,
The solvent is at least one selected from the group consisting of water, methanol, ethanol, propanol, butanol, isopropanol, tetrahydrofuran, ethyl acetate, chloroform, dimethyl sulfoxide, dimethylformamide and N-methyl-2-pyrrolidone Method for manufacturing a mixed medium separation membrane for phosphorus gas separation.
According to claim 16,
Before forming the selective layer, forming a surface coating layer on the surface of the porous polymer support by using poly(1-trimethylsilyl-1-propyne); a mixed medium separation membrane for gas separation that further comprises Manufacturing method of.
According to claim 16,
In the step of forming the optional layer, the coating amount of the optional layer is 2 to 10% by weight.
According to claim 16,
In the step of forming the selective layer, the selective layer forms an asymmetric structure composed of a dense layer having a thickness of 0.01 to 1 μm and a porous layer having a thickness of 0.1 to 5 μm.
According to claim 21,
The dense layer includes a polymer matrix including the polyvinylimidazole (PVI)-polyoxyethylene methacrylate (POEM) copolymer and a first metal-organic framework (MOF),
The method of manufacturing a mixed medium separation membrane for gas separation, wherein the porous layer is positioned on top of the dense layer and is made of a second metal-organic framework.
According to claim 16,
In the step of preparing the mixed medium separation membrane for gas separation, drying is performed at a temperature of 20 to 30 ° C. for 4 to 8 hours.
According to claim 16,
The porous polymer support is polysulfone,
Forming a surface coating layer using poly(1-trimethylsilyl-1-propyne) on the surface of the porous polymer support before the step of forming the selective layer; further comprising,
In preparing the copolymer, the polyvinylimidazole (PVI) and polyoxyethylene methacrylate (POEM) are mixed in a weight ratio of 25:75 to 35:65,
The initiator is azobisisobutyronitrile (AIBN),
In Formula 1, x and y are the repeating numbers of each repeating unit, x is 15 to 40, y is 60 to 90, x: y is 25:75 to 35:65, and n is an integer of 5 to 12 ego,
The metal organic framework comprises 40 to 50% by weight based on 100% by weight of the mixture,
The metal organic framework is ZIF-8,
The zinc (Zn) content of the ZIF-8 includes 5.7 to 6.4 atomic% based on the total number of atoms included in the selective layer,
The solvent is a mixed solvent of ethanol and water,
The coating amount of the optional layer is 2.7 to 3% by weight,
The selective layer has an asymmetric structure composed of a dense layer having a thickness of 0.05 to 0.5 μm and a porous layer having a thickness of 0.2 to 2 μm,
The selective layer has a surface roughness factor (Rq) of 75.7 to 79.1 nm and a porosity of 54 to 71% as a result of AFM analysis,
In the step of preparing the mixed medium separation membrane for gas separation, drying is performed at a temperature of 23 to 27 ° C. for 5 to 7 hours.

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