Filter, carbon dioxide concentration adjustment device, and carbon dioxide concentration adjustment method

Abstract

The present invention provides a filter capable of adjusting the concentration of CO2 in a mixed gas containing CO2 and other gases. [Solution] A filter comprising a film containing two-dimensional particles 10a, 10b, wherein the two-dimensional particles comprise one or more layers, and the layers are given by the following formula: M m X n A filter comprising layer bodies 1a, 1b represented by the formula (wherein M is at least one group 3, 4, 5, 6, or 7 metal, X is a carbon atom, a nitrogen atom, or a combination thereof, n is between 1 and 4, and m is greater than n and 5 or less), and modifications or terminations T (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom) 3a, 5a, 3b, 5b present on the surface of the layer bodies, through which a mixed gas containing CO2 and other gases passes, wherein the concentration of CO2 in the mixed gas after passing through the filter is higher than the concentration of CO2 in the mixed gas before passing through the filter.

Description

[Technical Field]

[0001] This disclosure relates to a filter, a carbon dioxide concentration adjustment device, and a carbon dioxide concentration adjustment method. [Background technology]

[0002] In recent years, various technological approaches have been taken to reduce CO2 emissions associated with the use of fossil fuels. One such approach that is attracting attention is carbon recycling, which treats CO2 as a carbon resource (carbon), recovers it, and reuses it as carbon compounds.

[0003] Patent Document 1 proposes a carbon dioxide separation membrane for use with mixed gases containing CO2, comprising a solution of a molybdenum carbonyl complex dissolved in a solvent and a support for holding the solution, and states that this separation membrane can increase only the amount of carbon dioxide permeate.

[0004] Patent Document 2 describes a carbon dioxide concentrating membrane having a multilayer structure in which the liquid film contains an ionic liquid or a polymer gel polymerized from an ionic liquid, which has a 5% thermoweight loss temperature of 250°C or higher, within an inorganic porous support, and a sealing film which is a film that does not allow the ionic liquid to pass through and has a 5% thermoweight loss temperature of 250°C or higher, with the liquid film sandwiched between two sealing films.

[0005] Patent Document 3 describes a highly efficient H2 / CO2 separation apparatus using a two-dimensional MXene molecular sieve membrane, stating that the molecular sieve membrane has pores, that molecules smaller than the diameter of the pores are drawn into the pores, and that molecules larger than the diameter of the pores remain outside the pores. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 6-142467 [Patent Document 2] Japanese Patent Publication No. 2010-36123 [Patent Document 3] Chinese Utility Model Registration No. 214287581 Specification [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Patent documents 1 and 2 only describe membranes using gels or ionic liquids as separation media. In the separation apparatus described in Patent Document 3, only the smaller diameter molecules (i.e., H2 molecules) of H2 and CO2 are allowed to pass through and separated, while the larger diameter molecules (i.e., CO2) remain in the mixed gas without being separated. As a result, the CO2 concentration in the mixed gas after passing through the separation apparatus becomes lower than before passing through.

[0008] This disclosure aims to provide a filter capable of adjusting the concentration of CO2 in a mixed gas containing CO2 and other gases. Furthermore, this disclosure aims to provide a CO2 concentration adjustment device equipped with such a filter and a CO2 concentration adjustment method using such a filter. [Means for solving the problem]

[0009] The filters in this disclosure are A filter comprising a film containing two-dimensional particles, The two-dimensional particle comprises one or more layers, The aforementioned layer is given by the following formula: M m X n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom) present on the surface of the layer body, This is a filter through which a mixed gas containing CO2 and other gases passes. The concentration of CO2 in the mixed gas after passing through the filter is higher than the concentration of CO2 in the mixed gas before passing through the filter. [Effects of the Invention]

[0010] The filters of this disclosure can adjust the concentration of CO2 in a mixed gas containing CO2 and other gases. The disclosure may also provide a CO2 concentration adjustment device equipped with such a filter and a CO2 concentration adjustment method using such a filter. [Brief explanation of the drawing]

[0011] [Figure 1] A schematic cross-sectional view showing MXene particles of a layered material in one embodiment of the present disclosure, where (a) shows single-layer MXene particles and (b) shows multilayer (exemplary, two-layer) MXene particles. [Figure 2] This is a schematic cross-sectional view showing a film in one embodiment of the present disclosure. [Figure 3] This is a bottom view showing a CO2 concentration adjustment device in one embodiment of the present disclosure. [Figure 4] This is a cross-sectional view taken along line IV-IV showing a CO2 concentration adjustment device in one embodiment of the present disclosure. [Modes for carrying out the invention]

[0012] (First embodiment: filter) The filters in this disclosure are A filter comprising a film containing two-dimensional particles, The two-dimensional particle comprises one or more layers, The aforementioned layer is given by the following formula: M m X n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom) present on the surface of the layer body, This is a filter through which a mixed gas containing CO2 and other gases passes. The concentration of CO2 in the mixed gas after passing through the filter is higher than the concentration of CO2 in the mixed gas before passing through the filter.

[0013] Because the filter of this disclosure has the above configuration, it can adjust the concentration of CO2 in a mixed gas containing CO2 and other gases, and in particular can increase the concentration of CO2 in the mixed gas.

[0014] This disclosure is not bound by any theory, but the reason why the filters of this disclosure can adjust the concentration of CO2 in a mixed gas containing CO2 and other gases is thought to be as follows: The filters of this disclosure include two-dimensional particles, and the two-dimensional particles have layers containing specific modifications or terminations T. Therefore, as the mixed gas passes through the filter, CO2 is attracted to and concentrated by the modifications or terminations T, and the concentration of CO2 in the mixed gas after passing through the filter is thought to be increased.

[0015] The filter in this embodiment is a filter through which a mixed gas containing CO2 and other gases passes, and the concentration of CO2 after passing through the filter is higher than the concentration of CO2 in the mixed gas before passing through the filter.

[0016] The CO2 concentration in the mixed gas before passing through the above filter can be calculated by recovering the mixed gas flowing into the filter, measuring the amount of substance of each component contained in the mixed gas using gas chromatography, and dividing the amount of substance of CO2 by the sum of the amounts of substance of each component contained in the mixed gas. The mixed gas may also be passed through the filter after the CO2 concentration has been measured. Furthermore, the concentration of CO2 in the mixed gas after passing through the above filter can be calculated by recovering the mixed gas after passing through the filter, measuring the amount of substance of the components contained in the mixed gas using gas chromatography, and dividing the amount of substance of CO2 by the sum of the amounts of substance of each component contained in the mixed gas.

[0017] The CO2 concentration (C2) in the mixed gas after passing through the above filter is more than 1.0 times the CO2 concentration (C1) in the mixed gas before passing through the above filter, on a molar basis, preferably 1.1 times or more and 10,000 times or less, and more preferably 1.2 times or more and 3,000 times or less. The CO2 concentration (C1) in the mixed gas before passing through the above filter and the CO2 concentration (C2) in the mixed gas after passing through the above filter may be measured values ​​obtained, for example, at a temperature of 40°C, with a differential pressure of 1 atm (1,013 hPa), using a mixed gas containing 10 mol% CO2, and continuing to pass the mixed gas through the filter for 10 hours or more.

[0018] The above mixed gas preferably contains, in addition to CO2, one or more gases selected from N2, O2, H2O, Ar, Ne, He, CH4, SO2, and NO2, and more preferably one or more gases selected from N2, O2, and H2O. The above mixed gas may further contain H2.

[0019] The CO2 permeation coefficient of the filter of the present disclosure (hereinafter, also referred to as "CO2 permeation coefficient") is preferably greater than the permeation coefficients of the other gases described above. Typically, the CO2 permeation coefficient of the filter of the present disclosure is greater than at least one selected from the N2 permeation coefficient of the filter of the present disclosure (hereinafter, the N2 permeation coefficient is also simply referred to as "N2 permeation coefficient") and the O2 permeation coefficient of the filter of the present disclosure (hereinafter, the O2 permeation coefficient is also simply referred to as "O2 permeation coefficient").

[0020] The CO2 permeation coefficient of the filter described above, as a converted value normalized with the filter thickness being 20 μm, is preferably 1×10 3 cc / m 2 / 24hr / atm or more and 1×10 6 cc / m 2 / 24hr / atm or less, more preferably 2×10 3 cc / m 2 / 24hr / atm or more and 8×10 5 cc / m 2 / 24hr / atm or less, even more preferably 4×10 3 cc / m 2 / 24hr / atm or more and 6×10 5 cc / m 2 / 24hr / atm or less. When the CO2 permeation coefficient of the filter is within such a range, the adjustment of the CO2 concentration can be suitably carried out.

[0021] The N2 permeation coefficient of the filter described above, as a converted value normalized with the filter thickness being 20 μm, is preferably 1 cc / m 2 / 24hr / atm or more and 1×10 4 cc / m 2 / 24hr / atm or less, more preferably 5 cc / m 2 / 24hr / atm or more and 8×10 3 cc / m 2 / 24hr / atm or less, even more preferably 10 cc / m 2 / 24hr / atm or more and 5×10 3 cc / m 2 / 24hr / atm or less. When the N2 permeation coefficient of the filter is within such a range, the adjustment of the CO2 concentration can be suitably carried out.

[0022] The O2 transmission coefficient of the above filter is preferably 0.1 cc / m², calculated as a normalized value based on a filter thickness of 20 μm. 2 / 24hr / atm or more 100cc / m 2 / 24hr / atm or less, more preferably 0.5cc / m 2 / 24hr / atm or more 50cc / m 2 / 24hr / atm or less, more preferably 1cc / m³ 2 / 24hr / atm or more 10cc / m 2 The CO2 concentration is less than / 24hr / atm. Since the O2 permeability coefficient of the filter is within the applicable range, the CO2 concentration can be appropriately adjusted.

[0023] In this disclosure, the permeability coefficient of the gas can be measured in accordance with JIS K 7126-1:2006.

[0024] The CO2 / N2 separation coefficient of the above filter is greater than 1, more preferably between 50 and 500, even more preferably between 100 and 300, and even more preferably between 150 and 300. By having the CO2 / N2 separation coefficient within this range, the CO2 concentration can be adjusted efficiently. In this disclosure, the CO2 / N2 separation coefficient in a given medium can be calculated by dividing the CO2 transmission coefficient of the medium by the N2 transmission coefficient.

[0025] The CO2 / O2 separation coefficient of the above filter is greater than 1, preferably between 10 and 5,000, more preferably between 50 and 2,000, and even more preferably between 70 and 1,500. By having the CO2 / O2 separation coefficient within this range, the CO2 concentration can be adjusted efficiently. In this disclosure, the CO2 / O2 separation coefficient in a given medium can be calculated by dividing the CO2 permeability coefficient of the medium by the O2 permeability coefficient.

[0026] The above filter is preferably a CO2 concentration adjustment filter, and more preferably a CO2 separation and concentration filter.

[0027] The above filter comprises a film containing two-dimensional particles and may further comprise a protective layer.

[0028] (2D particle) The above two-dimensional particle has one or more layers, The above layer is represented by the following formula: M m X n (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal, and may include at least one selected from the group consisting of so-called early transition metals, such as Sc, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and Mn.) X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. A two-dimensional material (which can be understood as a layered compound, "M") comprising a layer body represented by (the layer body may have a crystal lattice in which each X is located within an octahedral array of M) and a modification or termination T (where T is at least one selected from the group consisting of hydroxyl groups, fluorine atoms, chlorine atoms, oxygen atoms, and hydrogen atoms) present on the surface of the layer body (more specifically, at least one of two opposing surfaces of the layer body) m X n T s It can also be expressed as , where s is any number, and traditionally, x is sometimes used instead of s). Typically, n can be 1, 2, 3, or 4, but is not limited to these.

[0029] The above two-dimensional particles can be understood as a layered material or layered compound, "M m X n T s It can also be expressed as , where s is any number, and traditionally, x or z have sometimes been used instead of s. Typically, n can be 1, 2, 3, or 4, but is not limited to these.

[0030] Furthermore, in this disclosure, the above layer may be referred to as the MXene layer, and the above two-dimensional particles may be referred to as MXene two-dimensional particles or MXene particles.

[0031] In the above formula for MXene, M is preferably at least one selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and Mn, and more preferably at least one selected from the group consisting of Ti, V, Cr, and Mo.

[0032] MXene is expressed in the above formula: M m X n However, the following expressions are known: Sc2C, Ti2C, Ti2N, Zr2C, Zr2N, Hf2C, Hf2N, V2C, V2N, Nb2C, Ta2C, Cr2C, Cr2N, Mo2C, Mo 1.3 C, Cr 1.3 C, (Ti,V)2C, (Ti,Nb)2C, W2C, W 1.3 C, Mo2N, Nb 1.3 C, Mo 1.3 Y 0.6 C (In the above formula, "1.3" and "0.6" mean approximately 1.3 (=4 / 3) and approximately 0.6 (=2 / 3), respectively.) Ti3C2, Ti3N2, Ti3(CN), Zr3C2, (Ti,V)3C2, (Ti2Nb)C2, (Ti2Ta)C2, (Ti2Mn)C2, Hf3C2, (Hf2V)C2, (Hf2Mn)C2, (V2Ti)C2, (Cr2Ti)C2, (Cr2V)C 2, (Cr2Nb)C2, (Cr2Ta)C2, (Mo2Sc)C2, (Mo2Ti)C2, (Mo2Zr)C2, (Mo2Hf)C2, (Mo2V)C2, (Mo2Nb)C2, (Mo2Ta)C2, (W2Ti)C2, (W2Zr)C2, (W2Hf)C2, Ti4N3, V4C3, Nb4C3, Ta4C3, (Ti,Nb)4C3, (Nb,Zr)4C3, (Ti2Nb2)C3, (Ti2Ta2)C3, (V2Ti2)C3, (V2Nb2)C3, (V2Ta2)C3, (Nb2Ta2)C3, (Cr2Ti2)C3, (Cr2V 2)C3, (Cr2Nb2)C3, (Cr2Ta2)C3, (Mo2Ti2)C3, (Mo2Zr2)C3, (Mo2Hf2)C3, (Mo2V2)C3, (Mo2Nb2)C3, (Mo2Ta2)C3, (W2Ti2)C3, (W2Zr2)C3, (W2Hf2)C3, (Mo 2.7 V 1.3 )C3 (In the above formula, "2.7" and "1.3" mean approximately 2.7 (=8 / 3) and approximately 1.3 (=4 / 3), respectively.)

[0033] Typical examples include M m X n However, Ti2C, Ti3C2, Ti3(CN), (Cr2Ti)C2, (Mo2Ti)C2, (Mo2Ti2)C3, and (Mo 2.7 V 1.3 ) Represented by at least one selected from the group consisting of C3.

[0034] In particular, M m X n This could be Ti3C2.

[0035] Typically, in the above formula, M may contain Ti and X may be a carbon atom or a nitrogen atom; preferably, M may be Ti and X may be a carbon atom. For example, the MAX phase is Ti3AlC2 and MXene is Ti3C2T s (In other words, M is Ti, X is C, n is 2, and m is 3).

[0036] In this disclosure, MXene may contain a relatively small amount of A atoms derived from the precursor MAX phase, for example, 10% by mass or less relative to the original A atoms. The residual amount of A atoms is preferably 8% by mass or less, more preferably 6% by mass or less. However, even if the residual amount of A atoms exceeds 10% by mass, it may not be a problem depending on the application and usage conditions of the two-dimensional particles.

[0037] The above two-dimensional particle is an aggregate containing one layer of MXene particles (hereinafter simply referred to as "MXene particles") 10a (single-layer MXene particles), schematically illustrated in Figure 1(a). More specifically, the MXene particle 10a is M m X n The layer body (M) represented by m X n The MXene layer 7a has a layer 1a and modifications or terminations T3a, 5a present on the surface of the layer body 1a (more specifically, at least one of the two surfaces facing each other in each layer). Therefore, the MXene layer 7a is "M m X n T s It can also be expressed as , where s is any number.

[0038] The above two-dimensional particles may include one or more layers. Examples of MXene particles with multiple layers (multilayer MXene particles) include, but are not limited to, two-layer MXene particles 10b as schematically shown in Figure 1(b). In Figure 1(b), 1b, 3b, 5b, and 7b are the same as 1a, 3a, 5a, and 7a in Figure 1(a) described above. Two adjacent MXene layers of multilayer MXene particles (e.g., 7a and 7b) do not necessarily have to be completely separated, but may be in partial contact. The above MXene particle 10a may be a mixture of single-layer MXene particles 10a and multilayer MXene particles 10b, where the multilayer MXene particles 10b are individually separated and exist as a single layer, while unseparated multilayer MXene particles 10b remain.

[0039] Although not limited to this embodiment, the thickness of each MXene layer (corresponding to the MXene layers 7a and 7b described above) is, for example, 0.8 nm to 5 nm, particularly 0.8 nm to 3 nm (this can vary mainly depending on the number of M atomic layers contained in each layer), and the maximum dimension within a plane parallel to the layer (two-dimensional sheet plane) (which can correspond to the "in-plane dimension" of the particle) is, for example, 0.1 μm or more, particularly 1 μm or more, for example 200 μm or less, particularly 40 μm or less.

[0040] When MXene particles are laminated (multilayer MXene) particles, the interlayer distance (or void dimension, shown as Δd in Figure 1(b)) within each individual laminated particle is not particularly limited, for example, 0.8 nm or more and less than 10 nm, particularly 0.8 nm or more and 5 nm or less, and more particularly about 1 nm, and the maximum dimension in a plane perpendicular to the lamination direction (two-dimensional sheet plane) (which may correspond to the "in-plane dimension" of the particle) is for example 0.1 μm or more, particularly 1 μm or more, for example 100 μm or less, and particularly 20 μm or less.

[0041] The total number of layers in the MXene particles can be one or two or more, but for example, it can be between one and 20, and the thickness in the stacking direction (which can correspond to the "thickness" of the particles) can be between 0.8 nm and 20 nm.

[0042] In one embodiment, the two-dimensional particles in this embodiment preferably include two-dimensional particles with a small number of layers, obtained by delamination, which may contain the multilayer MXene particles described above. "Small number of layers" means, for example, that the number of stacked MXene layers is 6 or less. Furthermore, the thickness in the stacking direction of the multilayer MXene particles with a small number of layers is preferably 15 nm or less, and more preferably 10 nm or less. Hereinafter, these "multilayer MXene particles with a small number of layers" may be referred to as "low-layer MXene particles." Also, single-layer MXene particles and low-layer MXene particles may be collectively referred to as "single-layer / low-layer MXene particles."

[0043] In multilayer MXene particles with a small number of layers, the ratio of (average of the major axis of the 2D surface of the 2D particle) / (average of the thickness of the 2D particle) is 1.2 or more, preferably 1.5 to 10, and more preferably 2 to 5. Hereinafter, these "MXene particles with a small number of layers" may be referred to as "low-layer MXene particles." Also, single-layer MXene particles and low-layer MXene particles together may be referred to as "single-layer / low-layer MXene particles." This can improve the film formation properties of films containing 2D particles. The average of the major axis of the 2D surface of the 2D particle and the average of the thickness of the 2D particle can be determined by the method described later. Examples of the single-layer and low-layer MXene particles mentioned above include two-dimensional particles obtained through delamination.

[0044] In one embodiment, the two-dimensional particles of this embodiment preferably include single-layer MXene particles and thin-layer MXene particles, i.e., single-layer and thin-layer MXene particles. In the two-dimensional particles of this embodiment, the proportion of single-layer and thin-layer MXene particles with a thickness of 15 nm or less is preferably 90% to 100% by volume, more preferably 95% to 100% by volume. This can result in good film formation properties of the film containing the two-dimensional particles.

[0045] (Average value of the major axis of the two-dimensional plane of a two-dimensional particle) In this embodiment, the average value of the major axis of the two-dimensional surface of the two-dimensional particles is preferably 1 μm or more and 20 μm or less. Hereinafter, the average value of the major axis of the two-dimensional surface may be referred to as the "average flake size". The average value of the major axis of the two-dimensional surface is preferably 1.5 μm or more, more preferably 2.5 μm or more.

[0046] The average value of the major axis of the two-dimensional surface is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less, from the viewpoint of dispersibility in the dispersion medium.

[0047] (Average thickness of 2D particles) The average thickness of the two-dimensional particles in this embodiment is preferably 1 nm or more and 15 nm or less. The above thickness is preferably 10 nm or less, more preferably 7 nm or less, and even more preferably 5 nm or less. On the other hand, considering the thickness of the single-layer MXene particles, the lower limit of the thickness of the two-dimensional particles can be 1 nm.

[0048] The dimensions mentioned above can be determined as number-average dimensions (e.g., number-average of at least 40) based on scanning electron microscope (SEM), transmission electron microscope (TEM), or atomic force microscope (AFM) images, or as distances in real space calculated from the position of the (002) plane in reciprocal lattice space measured by X-ray diffraction (XRD).

[0049] The method for producing the above-mentioned two-dimensional particles will be described in detail below, but the invention is not limited to this embodiment.

[0050] The above method for manufacturing two-dimensional particles is: (a) preparing a predetermined precursor, and (b) Obtain an etched product by removing at least some of the A atoms from the precursor using an etching solution. (c) including cleaning the etched material to obtain an etched and cleaned material; (d) Mix the etching-cleaned material with a metal compound containing a metal cation to obtain an intercalated material in which the metal cation is intercalated into the etching-cleaned material. (e) The intercalation treatment product may further be stirred to obtain a delamination treatment product in which the intercalation treatment product is delaminated.

[0051] The following details each step.

[0052] ·Process (a) First, a predetermined precursor is prepared. In this embodiment, the predetermined precursor that can be used is the MAX phase, which is a precursor of MXene. The following formula: M m AX n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. A is at least one element from groups 12, 13, 14, 15, or 16. n is between 1 and 4, m is greater than n and less than or equal to 5. It is represented as follows.

[0053] The above M, X, n, and m are as described above.

[0054] A is at least one element from groups 12, 13, 14, 15, or 16, usually a group A element, typically from groups IIIA and IVA, and more specifically, may include at least one selected from the group consisting of Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, S, and Cd, preferably Al.

[0055] The MAX phase is M m X n The MAX phase has a crystal structure in which a layer composed of A atoms is located between two layers represented by (each X may have a crystal lattice located within an octahedral array of M). Typically, in the case of m=n+1, one layer of X atoms is placed between each of the n+1 layers of M atoms (these together are called "M"). m X n The MAX phase has repeating units in which a layer of A atoms ("A atomic layer") is positioned as the layer following the (n+1)th M atom layer, but is not limited to this. The A atomic layer (and possibly some M atoms) is removed by selective etching (removal and possibly layer separation) of A atoms (and possibly some M atoms) from the MAX phase, thereby exposing the M atoms. m X n The surface of the layer is modified by hydroxyl groups, fluorine atoms, chlorine atoms, oxygen atoms, and hydrogen atoms, etc., present in the etching solution (usually an aqueous solution containing hydrofluoric acid, but not limited to this), thereby terminating the surface.

[0056] The MAX phase described above can be manufactured by known methods. For example, TiC powder, Ti powder, and Al powder can be mixed in a ball mill, and the resulting mixed powder can be calcined in an Ar atmosphere to obtain a calcined body (block-shaped MAX phase). The calcined body can then be crushed with an end mill to obtain powdered MAX phase for the next process.

[0057] ·Process (b) In step (b), the above precursor M is removed using an etching solution. m AX n An etching process is performed to remove at least some of the A atoms from the precursor. m X n A processed material is obtained in which the layer represented by remains intact, while at least a portion of the layer composed of A atoms is removed.

[0058] The etching solution described above may contain acids such as HF, HCl, HBr, HI, sulfuric acid, phosphoric acid, and nitric acid, and typically an etching solution containing F atoms can be used. Examples of such etching solutions include a mixture of LiF and hydrochloric acid; a mixture of hydrofluoric acid and hydrochloric acid; and a mixture containing hydrofluoric acid. These mixtures may further contain phosphoric acid or the like. The etching solution described above is typically an aqueous solution.

[0059] Alternatively, for example, the MAX raw material (MAX phase) may be etched with an etching solution containing fluoride and acid (excluding hydrofluoric acid). By using fluoride and acid (excluding hydrofluoric acid) in the etching solution, hydrofluoric acid (HF) will be present in situ in the etching solution. Etching with an etching solution containing fluoride and acid (excluding hydrofluoric acid) may also be called the MILD method. As the fluoride, metallic fluorides such as lithium fluoride, sodium fluoride, and potassium fluoride can be used, and lithium fluoride may be particularly useful. When metallic fluorides are used, during the etching process, metal (metal ions) can be intercalated into the MXene particles along with etching the MAX raw material (MAX phase). As the acid (excluding hydrofluoric acid), for example, hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, acetic acid, formic acid, hypochlorous acid, and fluorosulfonic acid can be used, and hydrochloric acid may be particularly useful. Ammonium hydrogen difluoride may be used as the fluoride and acid (except hydrofluoric acid).

[0060] In this embodiment, etching with an etching solution containing hydrofluoric acid (ACID method) is preferred over etching with an etching solution containing fluoride and acid (excluding hydrofluoric acid) (MILD method) (see the examples described later).

[0061] Conventional conditions can be used for the etching operation using the above-mentioned etching solution and other related conditions.

[0062] ·Process (c) In step (c), the treated material obtained by the etching process is washed to obtain an etched and cleaned material. Washing is performed to thoroughly remove the acid and other substances used in the etching process.

[0063] Cleaning can be carried out using a cleaning solution, typically by mixing the etched material with the cleaning solution. Such a cleaning solution typically contains water, preferably pure water. Alternatively, it may also contain a small amount of hydrochloric acid or the like. The amount of cleaning solution mixed with the etched material and the method of mixing are not particularly limited. For example, such mixing methods include allowing the etched material and cleaning solution to coexist and performing stirring, centrifugation, etc. Stirring methods include using a handshake, automatic shaker, shear mixer, pot mill, etc. The degree of stirring, such as stirring speed and stirring time, should be adjusted according to the amount and concentration of the etched material to be treated. One or more cleanings with the above cleaning solution are sufficient, and it is preferable to perform multiple cleanings. For example, the washing with the washing solution described above may be carried out by sequentially performing steps (i) adding the washing solution (to the treated material or the remaining precipitate obtained in (iii) below) and stirring, step (ii) centrifuging the stirred material, and step (iii) discarding the supernatant after centrifugation. Steps (i) to (iii) may be repeated two or more times, for example, up to 15 times.

[0064] ·Process (d) In step (d), an intercalation treatment is performed using a metal compound containing metal cations to intercalate the etching and cleaning treatment product, thereby obtaining an intercalated product. As a result, the metal cations are intercalated in pairs of two adjacent M m X n An intercalated product is obtained, in which layers are intercalated between them. Such intercalation may be performed in a distributed medium.

[0065] The above metal cation preferably includes a Li cation, but may also include other metal cations.

[0066] Examples of the above-mentioned metal compounds include ionic compounds in which the above-mentioned metal cation and anion are bonded. For example, examples of the above-mentioned metal cation include iodide, phosphate, sulfate, sulfide salt, nitrate, acetate, and carboxylate salts. Lithium ions are preferred as the above-mentioned metal cation, metal compounds containing lithium ions are preferred as the metal compound, ionic compounds of lithium ions are more preferred, and one or more of lithium ion iodide, phosphate, and sulfide salts are even more preferred. If lithium ions are used as the metal ions, it is thought that the water hydrated with the lithium ions has the most negative dielectric constant, making it easier to form a single layer.

[0067] The specific method of intercalation processing is not particularly limited; for example, the etched and cleaned material and the metal compound may be mixed and stirred, or left to stand. For example, stirring at room temperature is one option. Examples of stirring methods include using a stirrer or other stirring bar, using a stirring blade, using a mixer, and using a centrifuge. The stirring time can be set according to the scale of production of the two-dimensional particles, for example, between 12 and 24 hours.

[0068] Intercalation processing may be carried out in the presence of a dispersion medium. Examples of dispersion media include water; organic media such as N-methylpyrrolidone, N-methylformamide, N,N-dimethylformamide, methanol, ethanol, dimethyl sulfoxide, ethylene glycol, and acetic acid.

[0069] The mixing order of the dispersion medium, the etched and cleaned material, and the metal compound is not particularly limited, but in one embodiment, the metal compound may be mixed after the dispersion medium and the etched and cleaned material have been mixed. Typically, the etching solution after etching may be used as the dispersion medium.

[0070] Intercalation treatment can typically be performed on an etched and cleaned product, but in another embodiment, it may be performed on the precursor simultaneously with the etching treatment. Specifically, such etching and intercalation treatment involves mixing the precursor, an etching solution, and a metal compound containing metal cations to remove at least some A atoms from the precursor, and intercalating the metal cations into the precursor from which the A atoms have been removed, thereby obtaining an intercalated product. As a result, at least some A atoms are removed from the precursor (MAX), and M in the precursor is also removed. m X n The layer remains, and multiple adjacent M m X n An intercalated product is obtained in which metal cations are intercalated between the layers.

[0071] The etching solution and metal compound used in the above etching and intercalation processes can be the same as those used in step (b), respectively.

[0072] ·Process (e) In step (e), the intercalation treatment is stirred to perform a delamination treatment, thereby obtaining a delaminated product. This stirring applies shear stress to the intercalation treatment, causing two adjacent M m X n At least a portion of the layers may be separated, and the MXene particles may be made into single or multiple layers.

[0073] The conditions for delamination are not particularly limited and can be carried out by known methods. For example, one method of applying shear stress to the intercalation material is to disperse the intercalation material in a dispersion medium and agitate it. Agitation methods include agitation using a mechanical shaker, vortex mixer, homogenizer, ultrasonic treatment, handshake, and automatic shaker. The degree of agitation, such as the agitation speed and agitation time, should be adjusted according to the amount and concentration of the material to be treated. For example, after the above intercalation slurry is centrifuged and the supernatant is discarded, pure water is added to the remaining precipitate, and layer separation is performed by agitation, for example, by handshake or automatic shaker. Removal of undelaminate material can be carried out by centrifuging, discarding the supernatant, and washing the remaining precipitate with water. For example, (i) pure water is added to the remaining precipitate after discarding the supernatant and agitated, (ii) centrifuged, and (iii) the supernatant is recovered. One possible method is to repeat the operations (i) to (iii) once or more, preferably two or more, and no more than ten times, to obtain a supernatant liquid containing single-layer and thin-layer MXene particles as the delamination product. Alternatively, this supernatant liquid may be centrifuged, the supernatant liquid after centrifugation discarded, and clay containing single-layer and thin-layer MXene particles may be obtained as the delamination product.

[0074] The delamination-treated material described above may be further washed. Such washing may remove at least some of the impurities. Hereinafter, the material obtained by washing the delamination-treated material will also be referred to as a delamination-washed material, and this delamination-washed material will be included within the technical scope of the delamination-treated material.

[0075] In one embodiment, the above cleaning may be carried out using a cleaning solution, typically by mixing the delamination product with the cleaning solution. In another embodiment, the above cleaning may be carried out by acid-treating the delamination product and then mixing the acid-treated product with the cleaning solution. Suitable acids may include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, perchloric acid, hydroiodic acid, hydrobromic acid, and hydrofluoric acid; organic acids such as acetic acid, citric acid, oxalic acid, benzoic acid, and sorbic acid; and the concentration of the acid in the acid solution may be adjusted as appropriate depending on the delamination product. Furthermore, the cleaning with the above cleaning solution may be carried out by sequentially performing steps (i) adding the cleaning solution (to the treated product or the remaining precipitate obtained in (iii) below) and stirring, step (ii) centrifuging the stirred product, and step (iii) discarding the supernatant after centrifugation. Steps (i) to (iii) may be repeated two or more times, for example, up to 15 times. The above stirring can be carried out using a handshake, automatic shaker, shear mixer, pot mill, etc. The acid treatment only needs to be performed once or more times, and if necessary, the operation of mixing with a fresh acid solution (an acid solution not used in the acid treatment) and stirring may be performed two or more times, for example, within a range of 10 times or less. The washing solution can be the same as the washing solution in step (c), for example, water may be used as the washing solution, and pure water is preferred. The above mixing can be carried out by the same method as the mixing method in step (c), for example, stirring, centrifugation, etc. Examples of stirring methods include using a handshake, automatic shaker, shear mixer, pot mill, etc.

[0076] The intermediates and target products in the manufacturing method described above, such as the intercalation-treated product and the delamination-treated product, may be dried by suction filtration, heat drying, freeze-drying, vacuum drying, etc.

[0077] The proportion of two-dimensional particles in the above-mentioned membrane is preferably 90% to 100% by volume, more preferably 95% to 100% by volume, and particularly may be 100% by volume. Having the proportion of two-dimensional particles in the above-mentioned membrane within this range allows for even better adjustment of the CO2 concentration in the mixed gas.

[0078] (film) The film in this embodiment will be described with reference to Figure 2. Figure 2 illustrates a film 30 obtained by stacking only two-dimensional particles 10, but is not limited to this. The film 30 may contain additives such as binders added during film formation, as needed. The amount of the additives in the film (when dry) is preferably 30% by volume or less, more preferably 10% by volume or less, even more preferably 5% by volume or less, and most preferably 0% by volume.

[0079] Methods for producing a film without using the above-mentioned binder include: filtering the supernatant liquid containing the two-dimensional particles obtained by the above-mentioned delamination by suction; mixing the two-dimensional particles with a dispersion medium and spraying it in the form of a slurry of appropriate concentration, followed by removing the dispersion medium by drying or the like, once or multiple times; or applying the slurry by methods such as bar coating, spin coating, or brush coating, followed by removing the dispersion medium by drying or the like, once or multiple times. The above spraying method may be, for example, an airless spraying method or an air spraying method, and specifically, a method of spraying using a nozzle such as a one-fluid nozzle, a two-fluid nozzle, or an airbrush. Examples of dispersion media that may be included in the slurry include water; organic media such as N-methylpyrrolidone, N-methylformamide, N,N-dimethylformamide, methanol, ethanol, dimethyl sulfoxide, ethylene glycol, and acetic acid.

[0080] Examples of the above-mentioned binders include acrylic resin, polyester resin, polyamide resin, polyolefin resin, polycarbonate resin, polyurethane resin, polystyrene resin, polyether resin, and polylactic acid.

[0081] The CO2 permeability coefficient of the membrane of the present disclosure (hereinafter, the CO2 permeability coefficient may also be simply referred to as the "CO2 permeability") is preferably greater than the permeability coefficients of the other gases described above. Typically, the CO2 permeability coefficient of the membrane of the present disclosure is greater than at least one selected from the N2 permeability coefficient of the membrane of the present disclosure (hereinafter, the N2 permeability coefficient may also be simply referred to as the "N2 permeability") and the O2 permeability coefficient of the membrane of the present disclosure (hereinafter, the O2 permeability coefficient may also be simply referred to as the "O2 permeability").

[0082] The CO2 permeability coefficient of the above-mentioned membrane, as a converted value normalized with the membrane thickness being 20 μm, is preferably 1×10 3 cc / m 2 / 24hr / atm or more and 1×10 4 cc / m 2 / 24hr / atm or less, more preferably 2×10 3 cc / m 2 / 24hr / atm or more and 8×10 3 cc / m 2 / 24hr / atm or less, even more preferably 3×10 3 cc / m 2 / 24hr / atm or more and 6×10 3 cc / m 2 / 24hr / atm or less. By having the CO2 permeability coefficient of the membrane within such a range, the adjustment of the CO2 concentration can be suitably carried out.

[0083] The N2 permeability coefficient of the above-mentioned membrane, as a converted value normalized with the membrane thickness being 20 μm, is preferably 1 cc / m 2 / 24hr / atm or more and 100 cc / m 2 / 24hr / atm or less, more preferably 5 cc / m 2 / 24hr / atm or more and 80 cc / m 2 / 24hr / atm or less, even more preferably 10 cc / m 2 / 24hr / atm or more and 50 cc / m 2 / 24hr / atm or less. By having the N2 permeability coefficient of the membrane within such a range, the adjustment of the CO2 concentration can be suitably carried out.

[0084] The O2 permeability coefficient of the above film is preferably 0.1 cc / m², calculated as a normalized value based on a film thickness of 20 μm. 2 / 24hr / atm or more 100cc / m 2 / 24hr / atm or less, more preferably 0.5cc / m 2 / 24hr / atm or more 50cc / m 2 / 24hr / atm or less, more preferably 1cc / m³ 2 / 24hr / atm or more 10cc / m 2 The CO2 concentration is less than / 24hr / atm. Since the O2 permeability coefficient of the membrane is within the applicable range, the CO2 concentration can be appropriately adjusted.

[0085] In the above membrane, the CO2 / N2 separation coefficient is greater than 1, more preferably 50 to 500, even more preferably 100 to 300, and even more preferably 150 to 300. By having the CO2 / N2 separation coefficient within this range, the CO2 concentration can be adjusted efficiently.

[0086] In the above membrane, the CO2 / O2 separation coefficient is greater than 1, preferably between 10 and 5,000, more preferably between 50 and 2,000, and even more preferably between 70 and 1,500. By having the CO2 / O2 separation coefficient within this range, the CO2 concentration can be adjusted efficiently.

[0087] The thickness of the film 30 is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm, and even more preferably 15 μm to 40 μm. Having the film 30 thickness within this range ensures good permeability of the mixed gas, allows for good adjustment of the CO2 concentration, and provides good handling of the filter.

[0088] The above filter may further comprise one or more protective layers.

[0089] The protective layer may be a layer that covers at least part or all of the film, and preferably a layer that covers all of the region in the film through which the mixed gas can pass. In the filter of this disclosure, one protective layer may be positioned in front of or behind the film along the direction of passage of the mixed gas, and two protective layers may be positioned in front and behind the film along the direction of passage of the mixed gas.

[0090] Preferably, the protective layer is laminated onto the film. Preferably, one main surface of the protective layer is in contact with one or both main surfaces of the film. For example, one main surface of the protective layer may be attached to one or both main surfaces of the film. When the protective layer is attached to the film, it may or may not be done via an adhesive layer.

[0091] The protective layer described above may be an organic material, specifically an organic resin such as acrylic resin, polyester resin (e.g., polyethylene terephthalate), polyamide resin, polyimide resin, polyamide-imide resin, polyolefin resin, polycarbonate resin, polyurethane resin, polystyrene resin, polyether resin, polylactic acid, or polyvinyl alcohol.

[0092] The CO2 permeability coefficient of the above protective layer is preferably 1 × 10⁻⁶ as a converted value normalized for a protective layer thickness of 20 μm. 4 cc / m 2 The current rate is 24hr / atm or higher, more preferably 1 × 10⁻⁶ 4 cc / m 2 / 24hr / atm or more, more preferably 5 × 10 4 cc / m 2 / 24hr / atm or more, 1 × 10 7 cc / m 2 It may be less than / 24hr / atm, and furthermore, 5 × 10 6 cc / m 2 It may be less than / 24hr / atm. The CO2 permeability coefficient of the protective layer being within the above range allows for good control of the CO2 concentration.

[0093] The thickness of the protective layer is preferably 5 μm to 1,000 μm, more preferably 10 μm to 500 μm, and even more preferably 20 μm to 200 μm. Having the protective layer thickness within this range allows for good adjustment of the CO2 concentration and ensures good handling of the filter.

[0094] The thickness of the filter is preferably 5 μm to 1,000 μm, more preferably 10 μm to 500 μm, and even more preferably 20 μm to 200 μm. Having the filter thickness within this range allows for good adjustment of the CO2 concentration and ensures good handling of the filter.

[0095] (Second embodiment: CO2 concentration adjustment device) The CO2 concentration adjustment device in this embodiment will be described with reference to the drawings. As shown in Figures 3 and 4, the CO2 concentration adjustment device in this embodiment comprises one or more filters and a support part for supporting the filters. The filters in this embodiment have the same configuration as the filters in the first embodiment, and their description will be omitted.

[0096] In the CO2 concentration adjustment device 40 of this embodiment, as shown in Figure 4, a mixed gas containing CO2 and other gases passes along the axial direction 60a of the support portion 60, from the first opening 61 to the second opening 62 in direction A. As a result, the mixed gas passes through the filter 50 attached to the through hole 63 of the support portion 60, thereby increasing the CO2 concentration in the mixed gas before and after passing through the filter 50, and allowing the CO2 concentration in the mixed gas to be adjusted.

[0097] The support portion 60 may be formed from, for example, one or more materials preferably selected from resin materials, inorganic materials, and metal materials.

[0098] The support portion 60 has a through hole 63 that penetrates along the axial direction 60a from the first opening 61 to the second opening 62. The cross-sectional shape of the first opening 61 or the second opening 62 and the cross-sectional shape of the through hole 63 may be the same or different. Also, the shape of the filter 50 and the cross-sectional shapes of the first opening 61 and / or the second opening 62 may be the same or different.

[0099] The support portion 60 may be in the form of a frame or a cylinder.

[0100] The diameter D of the through hole 63 is preferably 100 μm or more and 200 cm or less, more preferably 1 mm or more and 100 cm or less, and even more preferably 1 cm or more and 50 cm or less. The length L of the through hole 63 is preferably 1 cm or more and 100 cm or less, more preferably 2 cm or more and 50 cm or less, and even more preferably 5 cm or more and 20 cm or less. Furthermore, the ratio L / D of the diameter D of the through hole to the length L of the through hole 63 is preferably 0.1 or more and 10 or less, more preferably 0.5 or more and 5 or less, and even more preferably 1 or more and 2 or less.

[0101] The filter 50 is positioned between the first opening 61 and the second opening 62. In this embodiment, the number of filters 50 provided in the CO2 concentration adjustment device 40 is one or more, preferably two or more, more preferably two to five, and even more preferably two to four. This allows for more efficient adjustment of the CO2 concentration. It is preferable that two or more filters 50 are arranged along the axial direction 60a of the support portion 60.

[0102] The spacing between two or more adjacent filters 50 along the axial direction 60a may be the same or different. The ratio l / D of the diameter D of the through hole 63 to the average value l of the spacing between two or more adjacent filters 50 along the axial direction 60a is preferably 0.1 or more and 1 or less, more preferably 0.2 or more and 0.6 or less, and even more preferably 0.3 or more and 0.5 or less.

[0103] The CO2 concentration adjustment device 40 in this embodiment may further include a fan. The fan is preferably positioned between the first opening 61 and the second opening 62, and more preferably between one or more adjacent openings 50, for example, between the first opening 61 and the filter 50, and between two adjacent filters 50. Typically, the fan can be positioned along direction A in a direction that can increase the flow velocity of the mixed gas. This improves the transport efficiency of the mixed gas and allows for efficient adjustment of the CO2 concentration.

[0104] In this embodiment, the shape of the through-hole 63 is circular, but it is not limited to this and may be elliptical, quadrilateral, or the like.

[0105] In this embodiment, the number of filters 50 is 3, but it is not limited to this, and the number of filters 50 can be increased or decreased as desired.

[0106] (Third embodiment: Method for adjusting CO2 concentration) The CO2 concentration adjustment method of this disclosure includes adjusting the CO2 concentration in a mixed gas containing CO2 and other gases using a filter. The filter in this embodiment has the same configuration as the filter in the first embodiment and is therefore omitted from description.

[0107] The above adjustment of the CO2 concentration can preferably be carried out by passing a mixed gas containing CO2 and other gases through the filter. When a mixed gas containing CO2 and other gases is passed through the filter, the concentration of CO2 in the mixed gas after passing through the filter becomes higher than the concentration of CO2 in the mixed gas before passing through the filter, thus allowing the CO2 concentration in the mixed gas to be adjusted.

[0108] In a preferred embodiment, the CO2 concentration in the mixed gas may be adjusted by changing the number of filters through which the mixed gas containing CO2 and other gases passes. Increasing the number of filters can easily lead to a further increase in the CO2 concentration.

[0109] When a mixed gas containing CO2 and other gases is passed through a filter, the differential pressure before and after passing through the filter is preferably 0.1 atm to 3 atm, more preferably 0.3 atm to 2 atm, and even more preferably 0.5 atm to 1.5 atm. Being within this differential pressure range allows for stable adjustment of the CO2 concentration. The differential pressure before and after passing through the filter represents the difference between the pressure of the mixed gas before passing through the filter and the pressure of the mixed gas after passing through the filter. When two or more filters are used, the differential pressure before and after passing through the filter represents the difference between the pressure of the mixed gas that has not passed through the filter and the pressure of the mixed gas after passing through all filters.

[0110] When passing a mixed gas containing CO2 and other gases through the filter, the temperature of the mixed gas is preferably between 10°C and 80°C, more preferably between 15°C and 70°C, and even more preferably between 20°C and 60°C. This temperature range allows for stable adjustment of the CO2 concentration.

[0111] When passing a mixed gas containing CO2 and other gases through the filter, the flow rate of the mixed gas is preferably 10 mL / min to 1,000 mL / min, more preferably 20 mL / min to 800 mL / min, and even more preferably 100 mL / min to 600 mL / min. By keeping the flow rate of the mixed gas within this range, the CO2 concentration can be stably adjusted.

[0112] The time for passing the mixed gas containing CO2 and other gases through the filter is, for example, 1 minute or more, preferably 30 minutes or more, and more preferably 1 hour or more. By using the filter of this disclosure, continuous use (continuous processing) is possible, and although there is no particular upper limit, the time for passing the mixed gas through the filter may be, for example, 100 hours or less.

[0113] This disclosure provides the following aspects: [1] A filter comprising a film containing two-dimensional particles, The two-dimensional particle comprises one or more layers, The aforementioned layer is given by the following formula: M m X n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom) present on the surface of the layer body, This is a filter through which a mixed gas containing CO2 and other gases passes. A filter in which the concentration of CO2 in the mixed gas after passing through the filter is higher than the concentration of CO2 in the mixed gas before passing through the filter. [2] The filter according to [1], wherein the permeability coefficient of CO2 is greater than that of the other gases. [3] The filter according to [1] or [2], wherein at least one selected from the CO2 / N2 separation coefficient and the CO2 / O2 separation coefficient is greater than 1. [4] With an additional protective layer, A filter according to any one of [1] to [3], wherein one main surface of the protective layer is in contact with one or both main surfaces of the film. [5] It comprises one or more filters and a support part that supports the filters, The CO2 concentration adjustment device includes a filter described in any one of [1] to [4]. [6] The CO2 concentration adjustment device according to [5], wherein the number of filters is two or more. [7] This includes adjusting the CO2 concentration in a mixed gas containing CO2 and other gases using a filter. The method for adjusting the CO2 concentration includes a filter described in any one of [1] to [4]. [8] A method for adjusting the CO2 concentration according to [7], which includes adjusting the CO2 concentration in the mixed gas by changing the number of filters. [9] A filter comprising a film containing two-dimensional particles, The two-dimensional particle comprises one or more layers, The aforementioned layer is given by the following formula: M m X n (In the formula, M is at least one metal from groups 3, 4, 5, 6, or 7, X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom) present on the surface of the layer body, This is a filter through which a mixed gas containing CO2 and other gases passes. A filter in which the permeability coefficient for CO2 is greater than that for the other gases.

[10] The filter according to [9], wherein at least one selected from the CO2 / N2 separation coefficient and the CO2 / O2 separation coefficient is greater than 1.

[11] With an additional protective layer, The protective layer is laminated on the film, and the filter is as described in [9] or

[10] .

[12] It comprises one or more filters and a support part that supports the filters, The CO2 concentration adjustment device includes a filter as described in any one of [9] to

[11] .

[13] The CO2 concentration adjustment device according to

[12] , wherein the number of filters is two or more.

[14] This includes adjusting the CO2 concentration in a mixed gas containing CO2 and other gases using a filter. A method for adjusting the CO2 concentration, wherein the filter includes the filter described in any one of [9] to

[11] .

[15] A method for adjusting the CO2 concentration according to

[14] , which includes adjusting the CO2 concentration in the mixed gas by changing the number of filters. [Examples]

[0114] The present invention will be further described in detail by the following examples, but the present invention is not limited thereto.

[0115] (Example 1) • Preparation of MAX particles (precursors of MXene particles) TiC powder, Ti powder, and Al powder (all manufactured by Kojun Chemical Laboratory Co., Ltd.) were placed in a ball mill containing zirconia balls in a molar ratio of 2:1:1 and mixed for 24 hours. The resulting mixed powder was calcined at 1350°C for 2 hours under an Ar atmosphere. The resulting calcined body (block) was then pulverized with an end mill to a maximum size of 40 μm or less. This yielded Ti3AlC2 particles as MAX particles.

[0116] • Etching of the precursor (ACID method) Using the Ti3AlC2 particles (powder) prepared by the above method, etching was performed under the following etching conditions to obtain a solid-liquid mixture (slurry) containing solid components derived from the Ti3AlC2 powder. (Etching conditions) • Precursor: Ti3AlC2 (passed through a sieve with a mesh size of 45 μm) • Etching solution composition: 49% HF 6 mL H2O 18mL HCl (12M) 36mL • Amount of precursor added: 3.0g • Etching container: 100mL iBoy Etching temperature: 35℃ Etching time: 24 hours • Stirrer rotation speed: 400 rpm

[0117] • Cleaning after etching The slurry was divided into two portions and placed into two 50 mL centrifuge tubes. Centrifugation was performed at 3500 G using a centrifuge, and the supernatant was discarded. 40 mL of pure water was added to the remaining precipitate in each centrifuge tube, and the process of separating and removing the supernatant was repeated 11 times by centrifugation at 3500 G. After the final centrifugation, the supernatant was discarded, and Ti3C2T was extracted. x -water We obtained a separate medium clay.

[0118] Li intercalation Ti3C2T prepared by the above method x -Li intercalation was performed on a water-based clay medium using LiCl as the Li-containing compound under the following conditions, by stirring at 20°C to 25°C for 12 hours. (Conditions for intercalation of Li) ·Ti3C2T x - Moisture-based clay (MXene after washing): Solid content 0.75g LiCl: 0.75g Intercalation container: 100mL iBoy ·Temperature: 20℃ or higher and 25℃ or lower (room temperature) ·Time: 10h • Stirrer rotation speed: 800 rpm

[0119] Delamination The above Ti3C2T x - (i) 40 mL of pure water was added to the water medium clay and stirred in a shaker for 15 minutes, then (ii) centrifuged at 3500 G, and (iii) the supernatant was collected as a single-layer MXene-containing solution. This procedure (i) to (iii) was repeated a total of four times to obtain a single-layer MXene-containing supernatant. Furthermore, this supernatant was centrifuged using a centrifuge at 4300 G for 2 hours, and the supernatant was discarded to obtain a single-layer / single-layer MXene-containing clay as a single-layer / single-layer MXene-containing sample.

[0120] Preparation of MXene aqueous dispersion This MXene-containing clay and pure water were mixed in appropriate amounts to prepare an MXene-aqueous dispersion (MXene slurry) with a solid content concentration (MXene particle concentration) of 34 mg / mL.

[0121] • Fabrication of MXene film A 50 mL centrifuge tube was prepared, and the MXene aqueous dispersion (MXene solid content concentration 34 mg / mL) prepared as described above was diluted with pure water to a concentration of 1.5 wt%, and then added to the centrifuge tube to a total volume of 40.00 g. After that, the mixture was shaken for 15 minutes using an automatic shaker (SK5501.1, manufactured by FAST&FLUID) to disperse it in water.

[0122] The obtained slurry was set in a spray coater (manufactured in-house), and a DURAPORE substrate (Merck KGaA GVWP09050) was prepared as the substrate and spray-coated onto it. After spraying, it was dried with hot air, and this process of spraying again was repeated 200 times. The spray-formed MXene film, along with the substrate, was pre-dried in an atmospheric pressure oven at 80°C for 2 hours, and then dried in a vacuum oven at 150°C for approximately 15 hours. After that, the substrate was removed from the MXene film, and an MXene film for CO2 separation and concentration was fabricated. The thickness was 32.9 μm.

[0123] (Gas permeability measurement) The fabricated MXene membrane was cut so that each measurement sample was a perfect circle with a diameter of 6.0 cm. The circular samples were then placed in a gas permeability measuring instrument (GTR-10XACT, GTR Tech Co., Ltd.), and the CO2 permeability coefficient was measured under conditions of 25°C, 0%RH (dry gas), and a pressure difference of 76 cmHg. The O2 permeability coefficient was also measured under similar conditions, but with the pressure difference set to 188.5 cmHg. The measurement results are shown in Table 1. The permeability coefficients in Table 1 are converted values ​​normalized for a membrane thickness of 20 μm.

[0124] (Comparative Examples 1-28) Except for using the film shown in Table 1 instead of the MXene film, the permeability coefficient was measured in the same manner as in Example 1, and the results are shown in Table 1. The values ​​listed in Comparative Examples 2, 5-28 are standardized values ​​from the values ​​listed in "PLASTICS AGE ENCYCLOPEDIA <Advanced Edition>" by Tadahiko Katsuyoshi, 1998, p. 56, October 1997, Plastics Age, and "Plastics Molding Processing Data Book" p. 27, edited by the Japan Society for Composition Processing, Nikkan Kogyo Shimbun, March 1988.

[0125] [Table 1]

[0126] Table 1 shows that the MXene membrane has a higher CO2 permeability compared to the O2 permeability. This indicates that the MXene membrane has the ability to selectively adsorb CO2. Furthermore, when a mixed gas (including air) is permeated through the MXene membrane, CO2 is preferentially taken into the membrane, and as a result, CO2 can be efficiently separated from the mixed gas.

[0127] Furthermore, as shown in Table 1, the ratio of CO2 permeability to O2 permeability (CO2 permeability:O2 permeability) is approximately 78:1. In other words, by passing a mixed gas containing CO2 and O2 through a filter using an MXene membrane, the concentration of CO2 in the mixed gas can be concentrated 78 times compared to the mixed gas before filtering. Furthermore, it is theoretically possible to increase the CO2 concentration in the mixed gas beyond the initial 78 times by using two or more MXene membranes. In other words, the CO2 concentration can be adjusted by increasing or decreasing the number of filters (MXene membranes) through which the mixed gas passes. Moreover, since MXene is a solid, there is no possibility of leakage or saturation, and continuous processing is possible.

[0128] (Example 2) Similar to Example 1, MAX particles (precursors of MXene particles), etching of the precursors (ACID method), washing after etching, Li intercalation, and delamination were performed to obtain single-layer and thin-layer MXene-containing clays.

[0129] • Fabrication of MXene film A 50 mL centrifuge tube was prepared, and the MXene aqueous dispersion (MXene solid content concentration 34 mg / mL) prepared as described above was diluted with pure water to a concentration of 1.5 wt%, and then added to the centrifuge tube to a total volume of 40.00 g. After that, the mixture was shaken for 15 minutes using an automatic shaker (SK5501.1, manufactured by FAST&FLUID) to disperse it in water.

[0130] The obtained slurry was set in a spray coater, a polyimide film (Kapton, 75 μm thick, manufactured by Toray DuPont Co., Ltd.) was prepared as a substrate, and the slurry was spray-coated onto the substrate. After spraying, it was dried with hot air, and this process of spraying again was repeated 200 times.

[0131] The spray-formed MXene film, along with the substrate, was pre-dried in an atmospheric pressure oven at 80°C for 2 hours, and then dried in a vacuum oven at 150°C for approximately 15 hours. Subsequently, the MXene film for carbon dioxide separation and concentration was fabricated with the substrate still attached.

[0132] (Water vapor transmission rate measurement) The fabricated MXene film was cut along with the substrate so that each measurement sample was a perfect circle with a diameter of 6.0 cm. The circularly cut samples were then placed in a gas permeability measuring instrument (GTR-10XACT, GTR Tech Co., Ltd.), and the water vapor transmission coefficient was measured at a temperature of 40°C and a humidity of 90% RH. Water vapor and nitrogen gas were used for the measurements. The results are shown in Table 2. All values ​​in Table 2 are normalized to a film thickness of 20 μm.

[0133] (Comparative Examples 29-55) Except for using a laminated film consisting of the film shown in Table 2 and a polyimide film (Kapton, 75 μm thick, manufactured by Toray DuPont Co., Ltd.) instead of the MXene film, the water vapor transmission coefficient was measured in the same manner as in Example 2, and the results are shown in Table 2. The values ​​listed in Comparative Examples 29, 31, and 33-28 are standardized values ​​from the values ​​listed in "PLASTICS AGE ENCYCLOPEDIA <Advanced Edition>" by Tadahiko Katsuragi, 1998, p. 56, October 1997, Plastics Age, and "Plastic Molding Processing Data Book" p. 27, edited by the Japan Society for Composition Processing, Nikkan Kogyo Shimbun, March 1988.

[0134] [Table 2]

[0135] Table 2 shows that MXene is less permeable to water (water vapor) compared to other polymers. Therefore, it can be said that CO2 can be efficiently separated from a mixed gas (including air) in a dry state.

[0136] (Example 3) An MXene film was obtained in the same manner as in Example 1. The thickness of the MXene film was 0.016 mm. The MXene film was sandwiched between two protective layers (polyethylene terephthalate film, 100 μm thick) and subjected to measurement of the gas permeability coefficient. A gas / water vapor permeability analyzer (MORESCO-SuperDetect MAT-005, manufactured by MORESCO) was used to measure the gas permeability coefficient. With an effective permeation diameter of 40 mm, CO2, N2, or O2 was supplied at a pressure of 1 atm at a temperature of 40°C, and the measurement was continued until the permeability coefficient became constant. The same measurement was performed on the protective layers. The film thickness of the MXene film after measurement was measured to be 0.016 mm, which was unchanged compared to before the gas permeability coefficient measurement. The results are shown in Table 3. All permeability coefficients in Table 3 are normalized values ​​with a film thickness of 20 μm.

[0137] (Comparative Examples 57-60) The gas permeability coefficient was measured in the same manner as in Example 3, except that the film shown in Table 3 was used instead of the MXene film. All permeability coefficients in Table 3 are converted values ​​normalized to a film thickness of 20 μm.

[0138] [Table 3]

[0139] From the above, it was confirmed that the CO2 permeability coefficient of the MXene membrane was approximately 1,000 times higher than that of O2, and approximately 200 times higher than that of N2. On the other hand, the CO2 permeability coefficient of the polyvinyl chloride membrane, polyethylene membrane, polyethylene terephthalate membrane, and polypropylene membrane was 0.42 to 65.9 times that of O2. From this, it can be said that the MXene membrane has the ability to selectively adsorb CO2 and can efficiently separate CO2 from mixed gases. [Explanation of symbols]

[0140] 1a, 1b layer body (M m X n layer) 3a, 5a, 3b, 5b Modifier or Terminus T 7a, 7b MXene layer 10, 10a, 10b MXene particles (two-dimensional particles of layered material) 30 membrane 40 CO2 concentration adjustment device 50 filters 60 Support part 60a shaft 61 First opening 62 Second opening 63 Through hole A Direction of passage of the mixed gas

Claims

1. A filter comprising a film containing two-dimensional particles, The two-dimensional particle comprises one or more layers, The aforementioned layer is given by the following formula: M ｍ X ｎ (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal,) X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T present on the surface of the layer body (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom), CO ２ It is a filter through which a mixed gas containing and other gases passes. CO in the mixed gas after passing through the filter ２ The concentration of CO is the CO concentration in the mixed gas before it passes through the filter. ２ A filter with a higher concentration than [the specified value].

2. CO ２ The filter according to claim 1, wherein the permeability coefficient of is greater than that of the other gases.

3. CO ２ / N ２ Separation factor and CO ２ / O ２ The filter according to claim 1, wherein at least one selected from the separation factor and CO / O is greater than 1.

4. With an additional protective layer, The filter according to claim 1, wherein one main surface of the protective layer is in contact with one or both main surfaces of the film.

5. It comprises one or more filters and a support part that supports the filters, The filter includes the filter described in any one of claims 1 to 4, CO ２ Concentration adjustment device.

6. The number of filters is two or more, as described in claim 5. ２ Concentration adjustment device.

7. Using a filter, CO ２ CO in a mixed gas containing other gases ２ This includes adjusting the concentration. The filter includes the filter described in any one of claims 1 to 4, CO ２ Method for adjusting concentration.

8. By changing the number of filters, the CO in the mixed gas can be changed. ２ CO according to claim 7, which includes adjusting the concentration. ２ Method for adjusting concentration.

9. A filter comprising a film containing two-dimensional particles, The two-dimensional particle comprises one or more layers, The aforementioned layer is given by the following formula: M ｍ X ｎ (In the formula, M is at least one group 3, 4, 5, 6, or 7 metal,) X is a carbon atom, a nitrogen atom, or a combination thereof. n is between 1 and 4, m is greater than n and less than or equal to 5. The layer body is represented by and includes a modification or termination T present on the surface of the layer body (T is at least one selected from the group consisting of a hydroxyl group, a fluorine atom, a chlorine atom, an oxygen atom, and a hydrogen atom), CO ２ It is a filter through which a mixed gas containing and other gases passes. CO ２ A filter in which the permeability coefficient of one gas is greater than that of the other gases.

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