KR102319470B1 - the manufacturing method of accelerated transport membrane for separating carbon monoxide - Google Patents

Abstract

The present invention relates to a polymer membrane having a high carbon monoxide selectivity in a mixed gas containing carbon monoxide and a method for manufacturing the same. The polymer membrane according to the present invention can effectively separate carbon monoxide from a mixed gas, is easy to modularize and scale-up, and has excellent economic efficiency.

Description

The manufacturing method of accelerated transport membrane for separating carbon monoxide and its manufacturing method

The present invention relates to a polymer membrane having a high carbon monoxide selectivity in a mixed gas containing carbon monoxide and a method for manufacturing the same.

Steel by-product gas contains a large amount of carbon dioxide (CO ₂ ) and nitrogen (N ₂ ) along with carbon monoxide (CO). Until now, CO separation has been mostly separated by distillation or adsorption methods. However, compared to these processes, the membrane separation method is very advantageous in terms of energy and cost. However, it is very difficult to separate CO before _{CO 2} or N ₂ using a general polymer membrane. This is because the solubility of CO in most polymers is low and the size of the gas molecules is similar to that of _{CO 2} and N _{2 .}

As a prior art for a separation membrane for CO separation, there are supported ionic liquid membranes (SILM) using an ionic liquid, which is a liquid separation membrane ( liquid membrane). This type of membrane has a disadvantage that the impregnated liquid may leak when pressure is continuously applied. As a solid-state polymer membrane that can overcome these disadvantages, there is no membrane for CO separation developed so far, because it is very difficult to selectively separate _{CO through a general polymer compared to N 2} or CO _{2 .} A technique for separating CO ₂ by permeating it faster than CO has been reported, but in this case, a multi-step separation process is required to separate pure CO from by-product gas.

Therefore, in order to selectively separate only CO using a membrane separation method, it is necessary to develop a separation membrane that promotes only CO permeation while suppressing permeation of other gases.

The present invention has been devised to solve the above problems, and the present inventors have studied diligently to synthesize a polymer separation membrane capable of selectively separating carbon monoxide from a gas mixed with carbon monoxide. As a result, a copolymer with low carbon dioxide permeability was synthesized and a polymer membrane that selectively permeates carbon monoxide was prepared using this polymer copolymer.

Accordingly, an object of the present invention is a branched copolymer of the following [Formula 1]:

[Formula 1]

is to provide

Another object of the present invention is to provide a composition for preparing a separator comprising the branched copolymer of [Formula 1], a silver salt and a metal oxide.

Another object of the present invention, a polymeric porous support; and

a coating layer comprising a branched copolymer of [Formula 1], a silver salt and a metal oxide formed on the support;

It is to provide a polymer membrane comprising a.

Another object of the present invention is to provide a method for separating carbon monoxide gas from a mixed gas containing carbon monoxide gas using a polymer membrane.

However, the technical problem to be achieved by the present invention is not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the object of the present invention as described above, the present invention is a branched copolymer of the following [Formula 1]:

[Formula 1]

provides

In Formula 1, x: y is 1:0.5 to 1:0.05, and n is 24 to 25.

In addition, the present invention provides a composition for preparing a separation membrane comprising the branched copolymer of [Formula 1], a silver salt, and a metal oxide.

In addition, the present invention is a polymeric porous support; and

a coating layer comprising a branched copolymer of [Formula 1], a silver salt and a metal oxide formed on the support;

It provides a polymer membrane comprising a.

In addition, the present invention provides a method for separating carbon monoxide gas from a mixed gas containing carbon monoxide gas using a polymer separation membrane.

The accelerated transport separation membrane for carbon monoxide separation and a manufacturing method thereof according to the present invention provide a polymer separation membrane with high CO permeability, and the separation membrane shows significantly higher CO separation performance compared to conventional liquid membranes, and is simple to manufacture and easy to scale up. It is expected that it can be usefully used to separate high-purity CO gas from the mixed gas.

1 is a diagram showing the synthesis mechanism of (a) PEGBEM-PMA and (b) PEGBEM-POEM copolymer (control).
2 is an SEM and TEM photograph of MgO-NS ((a) a low magnification SEM photograph, (b) a high magnification SEM photograph, (c) a TEM photograph).
3 is a graph analyzing the PEGBEM-PMA branched copolymer ((a) FT-IR spectrum, (b) XRD pattern graph).
4 is a graph analyzing the interaction between the PEGBEM-PMA branched copolymer and the silver salt through SAXS ((a) PEGBEM-PMA, (b) PEGBEM-PMA/AgBF ₄ /MgO-NS composite membrane of various ratios ).
5 is an XPS result confirming the interaction between the PEGBEM-PMA copolymer and the complex and the role of MgO-NS ((a) (i) PEGBEM-PMA (5:5)/AgBF ₄ /MgO-NS, ( ii) PEGBEM-PMA (7:3)/AgBF ₄ /MgO-NS and (iii) PEGBEM-PMA (9:1)/AgBF ₄ /MgO-NS.(b) (i) PEGBEM-PMA (7:3) ), (ii) PEGBEM-PMA (7:3)/AgBF ₄ and (iii) PEGBEM-PMA (7:3)/AgBF ₄ /MgO-NS).
6 is a Raman spectrum graph with time of PEGBEM-PMA (7:3)/AgBF _{4 /MgO-NS after CO purge.
7 is a graph measuring the amount of CO 2} absorbed according to the pressure of the polymer membrane ((a) polymer matrix, (b) PEGBEM-PMA (7:3)/AgBF ₄ /MgO-NS composite membrane).
8 is a microstructure photograph of a polymer matrix and a composite film observed through TEM ((a) PEGBEM-PMA (7:3), (b) MgO-NS, (c) PEGBEM-PMA (7:3)/ AgBF ₄ /MgO-NS).
9 is a graph showing CO permeability vs. selectivity ((a) CO permeability vs. CO/CO ₂ selectivity, (b) CO permeability vs. CO/N ₂ selectivity).
10 is a cross-sectional SEM image of a PEGBEM-PMA/AgBF ₄ /MgO-NS composite film ((a) PEGBEM-POEM (5:5)/AgBF ₄ /MgO-NS, (b) PEGBEM-PMA (7:3). )/AgBF ₄ /MgO-NS).

Hereinafter, the present invention will be described in detail.

In order to achieve the object of the present invention as described above, the present invention is a branched copolymer of the following [Formula 1]:

[Formula 1]

provides

In Formula 1, x: y is 1:0.5 to 1:0.05, and n is 24 to 25.

As used herein, "copolymer" refers to a polymer derived from one or more species of monomers. Polymerization of monomers into copolymers is called copolymerization. According to the arrangement of each monomer in the polymer, it is classified into alternating type, block type, random type, branch type, crosslinking type, and the like.

The present invention provides a composition for preparing a separation membrane comprising the branched copolymer of [Formula 1] and a silver salt and a metal oxide.

Here, "salt" refers to a metal salt, and refers to a metal compound formed with water through a neutralization reaction of an acid containing a metal.

In an embodiment of the present invention, the silver salt may be silver tetrafluoroborate (AgBF ₄ ) or silver nitrate (AgNO ₃ ).

As another embodiment of the present invention, the metal oxide is magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), zinc oxide (ZnO), tin oxide (SnO), iron oxide (FeO), titanium oxide (TiO _{2 )} ) or zirconium oxide (ZrO ₂ ).

In an embodiment of the present invention, the branched copolymer has a poly(ethylene glycol)bihenyl ether methacrylate:methacrylic acid (PEGBEM:MA) ratio of 9:1 to 5:5, preferably 8:2. to 6:4, for example, a weight ratio of 7:3, but is not limited thereto.

The present invention, a polymeric porous support; and

a coating layer comprising a branched copolymer of [Formula 1], a silver salt and a metal oxide formed on the support;

It provides a polymer membrane comprising a.

As an embodiment of the present invention, the porous support is polysulfone (poly sulfone), polyacrylonitrile (polyacrylonitrile), polyvinylidene fluoride (polyvinylidene fluoride), polyethylene (polyethylene), polypropylene (polypropylene), cellulose acetate ( cellulose acetate) or polyether sulfone.

In an embodiment of the present invention, the porous polymer support may be in the form of a sheet or a hollow fiber.

Here, "hollow fiber type" refers to a membrane molded into a hollow filament or thin cylindrical shape as one of the types of separation membranes. Usually, a plurality of hollow fiber membranes are bundled and one or both ends are fixed with resin or the like.

In the present invention, carbon monoxide gas can be separated from a mixed gas containing carbon monoxide gas by using the polymer separation membrane prepared by the above method, and preferably, CO/CO ₂ , CO/N ₂ Mixed gas may be used, but this It is not limited.

Hereinafter, preferred examples are presented to help the understanding of the present invention. However, the following examples are only provided for easier understanding of the present invention, and the contents of the present invention are not limited by the following examples.

<Example 1> PEGBEM-PMA branched copolymer synthesis

The PEGBEM-PMA branched copolymer was synthesized via free radical polymerization of methacrylic acid (MA) and poly(ethylene glycol)bihenyl ether methacrylate (PEGBEM) ( FIG. 1 ). Three copolymers were synthesized with monomer ratios (PEGBEM:MA) of 9:1, 7:3, and 5:5, respectively, and the reaction was carried out with the total weight of the monomers being 10 g. When the MA monomer exceeds 50% by weight of the total, the reaction could not proceed uniformly due to the low solubility of the synthesized polymer. After dissolving the two monomers in 50 mL of ethyl acetate, 0.01 g of azobisisobutyronitrile (AIBN) as an initiator was added and stirred. _{After purging with N 2} for 1 hour, the reaction was carried out for 24 hours in an oil bath at 70° C. while stirring the solution. After the reaction, in order to remove the unreacted material, the reaction solution was poured into excess n-hexane with strong stirring so that the polymerized polymer was precipitated. This process was repeated so that the remaining unreacted material was completely removed. The synthesized branched copolymer was dried in a vacuum oven to remove residual solvent.

_{As a control, PEGBEM-POEM, a polymer containing POEM (poly(oxyethylene methacrylate)), a monomer with high CO 2} affinity, was synthesized as a control instead of MA (Fig. 1). The same method as PEGBEM-PMA with the ratio of the two monomers being 5:5. To obtain a copolymer, this polymer _{exhibited high CO 2} selective separation performance with a _{CO 2} /N ₂ selectivity of 84.7.

<Example 2> Preparation of accelerated transport membrane for carbon monoxide separation

A separation membrane containing MgO-NS and AgBF ₄ in a PEGBEM-PMA polymer matrix was prepared in the form of a composite membrane. SEM and TEM pictures of MgO-NS were taken ( FIG. 2 ). PEGBEM-PMA polymer was dissolved in ethanol at 10 wt%. _{AgBF 4} and MgO-NS were added to this solution, and a coating solution was prepared by stirring. Polymer in all samples: AgBF _4: the weight ratio of MgO-NS is from 1: 3: was set to 0.05. The prepared solution was coated on a polysulfone support membrane using an RK coater. The separator was stored in a vacuum oven for 1 day to completely dry.

<Experimental Example 1> PEGBEM-PMA branched copolymer analysis

PEGBEM-PMA copolymers were synthesized in monomer ratios of 9:1, 7:3 and 5:5, respectively. When the MA monomer exceeds 50% by weight of the total, free radical polymerization could not be carried out due to low solubility. PEGBEM has high mechanical strength during polymerization due to the formation of a crystalline phase by 20 consecutive methylene groups and 24 ethylene oxide groups. As a control, a branched copolymer of PEGBGEM-POEM was synthesized and used for gas separation performance comparison. In a previous study, PEGBEM-POEM membranes with a weight ratio of 5:5 _{showed high CO 2} /N ₂ selectivity. Successful polymerization of the PEGBEM-PMA branched copolymer was confirmed by FT-IR measurement (Fig. 3).

The microstructure of the PEGBEM-PMA copolymer and the crystallinity of the separator composite can be confirmed through the WAXS pattern of FIG. 3b. As the MA content of the PEGBEM-PMA polymer increases, the center of the peak moves to a lower angle, and it can be seen that the d-spacing in the polymer chain gradually increases. This increase in the interchain distance is caused by the introduction of MA into the stacked PEGBEM region. PEGBEM plays a key role in forming nanostructures by continuous methylene and ethylene oxide chains. When AgBF ₄ and MgO-NS are introduced, the intensity of the peak decreases sharply, which is due to the temporary cross-linking caused by coordination between Ag ions and the ether or ester functional groups of PEGBEM-PMA.

The interaction between the PEGBEM-PMA branched copolymer and the silver salt was confirmed through SAXS analysis (FIG. 4). In Fig. 4a, the PEGBEM-PMA branched copolymer did not show a conspicuous peak but a single peak in the PEGBEM-PMA (9:1) and PEGBEM-PMA (7:3) samples when silver salt was included (Fig. 4b). was clearly observed, and the d-spacing calculated from the Bragg formula was 7.5 nm. From this, _{it can be seen that the introduction of AgBF 4} and MgO-NS improves the regularity of the PEGBEM-PMA polymer nanostructure through interaction. On the other hand, such a band did not appear in PEGBEM-PMA (5:5), where the amount of functional groups contained in PEGBEM was relatively small. can be expected

<Experimental Example 2> Effect of polymer medium

XPS analysis confirmed the interaction between the PEGBEM-PMA copolymer and the complex and the role of MgO-NS. In order to obtain high CO separation performance compared to _{CO 2} and N _{2 , CO 2} permeation should be suppressed and only CO permeation should be selectively enhanced. 5a, MgO-NS and AgBF ₄ show the lowest binding energy (367.78 eV) when introduced into the PEGBEM-PMA (7:3) matrix. This indicates that the electrostatic interaction between MgO-NS and silver ions is strongest in the PEGBEM-PMA (7:3) matrix. Therefore, it was determined that PEGBEM-PMA (7:3) copolymer was most suitable as a matrix for _{CO/CO 2} and CO/N _{2 separation membranes.}

In addition, in order to investigate the effect of MgO-NS, _{the peak of Ag 3d 5/2} of PEGBEM-PMA (7:3) was confirmed according to the presence or absence of MgO-NS ( FIG. 5b ). When MgO-NS was introduced, lower binding energy was confirmed, and therefore, it was confirmed that both the composition of the polymer matrix and the introduction of MgO-NS are decisive for the activity and stability of silver ions.

The direct interaction between PEGBEM-PMA (7:3)/AgBF ₄ /MgO-NS membrane and CO molecules was confirmed by Raman analysis ( FIG. 6 ). Before the measurement, the PEGBEM-PMA (7:3)/AgBF ₄ /MgO-NS sample was exposed to CO gas for one day, and the change of the Raman spectrum with time was confirmed. In a CO environment, ^{the Raman band between 1400 and 1600 cm -1} disappears, and when exposed to air, it starts to appear again after a few minutes. From this, it can be confirmed that the temporary binding through the interaction between the CO transporter and the CO molecule contained in the PEGBEM-PMA membrane can be confirmed.

_{The interaction between the CO 2} molecule and the copolymer was confirmed by measuring the amount of CO _{2 absorbed by the separation membrane (FIG. 7a).} Change in _{CO 2} absorption according to pressure of PEGBEM-POEM (5:5) and PEBAX 1657 (commercial block copolymer) as controls for comparison with PEGBEM-PMA (7:3) polymer matrix, which was expected to have the lowest CO _{2 permeability} was confirmed. _{The CO 2} absorption of the PEGBEM-PMA copolymer was 0.021 mmol/g, which was significantly lower than that of the control, and thus CO ₂ permeation could be effectively suppressed.

_{In FIG. 7b, the CO 2} and CO absorption amount of the PEGBEM-PMA (7:3)/AgBF ₄ /MgO-NS membrane was confirmed. The absorption of CO _{was observed to be higher than that of CO 2} because the affinity for CO molecules was increased due to the presence of the silver salt. Therefore, in the PEGBEM-PMA (7:3)/AgBF ₄ /MgO-NS membrane, the diffusion of CO is promoted through the silver salt, so that it can permeate faster than _{CO 2 .}

8 shows the microstructure of the polymer matrix and the composite film observed through TEM. PEGBEM-PMA (7:3) does not show a special structure, and in the case of MgO-NS, a porous structure is observed. The thin thickness and porous morphology of MgO-NS improves the interfacial properties between the polymer matrix and the inorganic particles without structural defects. 8c, it can be seen that MgO-NS and PEGBEM-PMA have excellent miscibility.

<Experimental Example 3> Carbon monoxide separation performance of the prepared transport separation membrane for carbon monoxide separation

When PEGBEM-PMA (5:5) was used as a matrix, the separator showed serious defects and showed poor performance. As can be seen in FIG. 10 , the selective layer of the composite membrane exhibited a thickness of about 2 μm, and it was confirmed that MgO-NS was well dispersed in the matrix.

Sample N ₂ (GPU) CO ₂ (GPU) CO (GPU) α (CO/N ₂ ) α (CO/CO ₂ ) PEBAX 1657 0.7 20 0.4 0.57 0.02 PEGBEM-POEM (5:5) 0.26 20.5 0.2 0.7 0.01 PEGBEM-PMA (9:1) 3.8 13.5 2.3 0.6 0.17 PEGBEM-PMA (7:3) 6.2 7.5 4.7 0.7 0.6 PEGBEM-PMA (5:5) Defective PEBAX/AgBF ₄ /MgO-NS 8 30.5 37.1 4.6 1.2 PEGBEM-POEM (5:5)/AgBF ₄ /MgO-NS 2.5 21.8 4.9 2 0.2 PEGBEM-PMA (9:1)/AgBF ₄ /MgO-NS 20.6 20.8 48.5 2.3 2.3 PEGBEM-PMA (7:3)/AgBF ₄ /MgO-NS 5.3 6.5 79 14.7 12 PEGBEM-PMA (5:5)/AgBF ₄ /MgO-NS Defective

Table 1 summarizes the CO separation performance of several membranes and polymer/AgBF ₄ /MgO-NS composite membranes. As confirmed from the gas uptake results, the PEGBEM-POEM (5:5) composite _{showed a very high CO 2} permeability of 21.8 GPU. The diffusivity increased with the addition of porous MgO-NS, resulting in slightly higher _{N 2 permeability compared to the pure PEGBEM-POEM (5:5) membrane.} The CO permeability was slightly higher than the _{N 2} permeability due to the facilitated transport of silver ions, but the CO/CO ₂ selectivity was less than 1 _{due to the high CO 2 affinity.} When the polymer matrix was PEGBEM-PMA, _{low CO 2} was exhibited by MA with repulsive force against _{CO 2 molecules.} At the same time, the CO permeability was maximized due to the excellent miscibility with the silver salt and MgO-NS _{, confirming the high performance of the GPU with CO/N 2} selectivity of 14.7, CO/CO ₂ selectivity of 12, and CO permeability of 79. In Figure 9, CO permeability vs. The selectivity of CO/CO ₂ and CO/N ₂ is shown as a graph, and it can be seen that the performance of the separation membrane presented in the present invention exhibits very superior CO separation performance compared to the previously developed CO separation membrane.

The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

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Claims (10)

Branched copolymer of the following [Formula 1]:
[Formula 1]

In Formula 1, x: y is 1:0.5 to 1:0.05, and n is 24 to 25.
A composition for preparing a separator comprising a branched copolymer of the following [Formula 1] and a silver salt and a metal oxide:
[Formula 1]

In Formula 1, x: y is 1:0.5 to 1:0.05, and n is 24 to 25.
3. The method of claim 2,
The silver salt is silver tetrafluoroborate (AgBF ₄ ) or silver nitrate (AgNO ₃ ), a composition for manufacturing a separator.
3. The method of claim 2,
The metal oxide is magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), zinc oxide (ZnO), tin oxide (SnO), iron oxide (FeO), titanium oxide (TiO ₂ ) or zirconium oxide (ZrO ₂ ), A composition for manufacturing a separator.
3. The method of claim 2,
The branched copolymer is poly (ethylene glycol) bihenyl ether methacrylate as a monomer: methacrylic acid (PEGBEM: MA) in a weight ratio of 9: 1 to 5: 5, a composition for preparing a separator.
Polymeric porous support; and
A coating layer comprising a branched copolymer of the following [Formula 1], a silver salt and a metal oxide formed on the support;
A polymer membrane comprising:
[Formula 1]

In Formula 1, x: y is 1:0.5 to 1:0.05, and n is 24 to 25.
7. The method of claim 6,
The polymer porous support is polysulfone (poly sulfone), polyacrylonitrile (polyacrylonitrile), polyvinylidene fluoride (polyvinylidene fluoride), polyethylene (polyethylene), polypropylene (polypropylene), cellulose acetate (cellulose acetate) or polyether Polyether sulfone material, polymer membrane.
7. The method of claim 6,
The porous polymer support is a sheet-type or hollow fiber support membrane, a polymer separation membrane.
A method for separating carbon monoxide gas from a mixed gas containing carbon monoxide gas using the polymer membrane according to any one of claims 6 to 8.
10. The method of claim 9
The gas mixture is a mixture gas of carbon monoxide gas and carbon dioxide gas or a mixture gas of carbon monoxide and nitrogen gas, a method for separating carbon monoxide gas.

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