Separation membrane composite and method for manufacturing separation membrane composite

Abstract

A separation membrane composite (1) is provided with: a porous support (11); an intermediate film (12) which is a polycrystal film provided on the surface of the support (11) and has pores derived from a skeleton structure, the average pore diameter of the pores being smaller than the average pore diameter of the pores in the vicinity of the surface of the support (11); and a separation film (13) which is an inorganic film provided on the intermediate film (12) and has a regular pore structure. A functional group is introduced into the pores in the surface layer (14) of the separation film (13) away from the intermediate film (12). In the separation membrane composite (1), the separation film (13) can be appropriately formed on the porous support (11), and the permeation rate of a prescribed substance can be increased in the separation film (13) into which the functional group is introduced.

Description

Technical Field

[0001] This invention relates to a separation membrane composite and a method for manufacturing the separation membrane composite.

[0002] [Reference for related applications]

[0003] This application claims priority to Japanese Patent Application JP2021-60419, filed on March 31, 2021, the entire disclosure of which is incorporated herein by reference. Background Technology

[0004] In recent years, the use of mesoporous materials such as mesoporous silica to separate carbon dioxide (CO2) has been proposed. The precursor solutions used as raw materials for mesoporous materials typically employ organic solvents such as ethanol and IPA, resulting in high fluidity. Therefore, when fabricating mesoporous films on porous supports, the precursor solution permeates into the porous support, making film formation very difficult.

[0005] Therefore, Japanese Patent No. 4212581 (Document 1) discloses a method for pretreatment in the fabrication of mesoporous silica films, which involves impregnating flowing paraffin wax into the pores of a porous support. A precursor solution is then coated onto the porous support impregnated with flowing paraffin wax using a spin-coating method to form a gel film. Next, the surfactant in the flowing paraffin wax and the gel film is removed by calcination, thereby obtaining a mesoporous silica film. Subsequently, a silane coupling agent with basic functional groups is used to introduce basic functional groups into the mesoporous silica film.

[0006] However, when forming mesoporous silica films on porous supports such as tubular or monolithic structures, spin coating cannot be used due to shape limitations. Furthermore, when using methods that impregnate such porous supports with flowing paraffin, it is not easy to ensure the paraffin is fully impregnated throughout the entire porous support, resulting in significant variations (uniformity) in the thickness of the mesoporous silica film. Consequently, defects such as poor coating of the mesoporous silica film occur. This problem may also occur when forming separation membranes other than mesoporous silica films.

[0007] Furthermore, in the mesoporous silica membrane of Reference 1, the CO2 separation performance was improved due to the introduction of basic functional groups. However, it can be assumed that the CO2 permeation rate would decrease if basic functional groups were introduced into the generally porous pores. This problem also exists when functional groups that adsorb substances other than CO2 are introduced. Summary of the Invention

[0008] The present invention relates to a separation membrane composite, the purpose of which is to suitably form a separation membrane on a porous support, and to increase the permeation rate of a specified substance in a separation membrane incorporating functional groups.

[0009] A preferred embodiment of the present invention relates to a separation membrane composite comprising: a porous support; an intermediate membrane, which is a polycrystalline membrane disposed on the surface of the support and has pores originating from a framework structure, the average pore diameter of which is smaller than the average pore diameter of pores near the surface of the support; and a separation membrane, which is an inorganic membrane disposed on the intermediate membrane and having a regular pore structure. Functional groups are introduced into the pores of the separation membrane located away from the surface layer of the intermediate membrane.

[0010] According to the present invention, a separation membrane can be suitably formed on a porous support, and the permeation rate of a specified substance can be increased in a separation membrane incorporating functional groups.

[0011] Preferably, the average pore size of the intermediate membrane is 0.1 to 1.0 nm, the average pore size of the separation membrane is 0.5 to 10.0 nm, and the average pore size of the intermediate membrane is smaller than the average pore size of the separation membrane.

[0012] Preferably, the intermediate membrane is a membrane formed of zeolite or a metal-organic structure.

[0013] Preferably, the separation membrane is a membrane formed of mesoporous material, zeolite or metal-organic structure.

[0014] Preferably, in the X-ray diffraction pattern obtained by irradiating the surface of the separation membrane with X-rays, a peak appears in the range of 2θ = 1 to 4°.

[0015] Preferably, the thickness of the intermediate membrane is 5 μm or less, and the thickness of the separation membrane is 1 μm or less.

[0016] Preferably, the functional group is an amino group.

[0017] The present invention also relates to a method for manufacturing a separation membrane composite. A preferred embodiment of the present invention includes the following steps: a) preparing a porous support; b) forming an intermediate membrane on the surface of the support, wherein the intermediate membrane is a polycrystalline membrane having pores derived from a framework structure, the average pore diameter of the pores being smaller than the average pore diameter of pores near the surface of the support; c) forming a separation membrane on the intermediate membrane, wherein the separation membrane is an inorganic membrane having a regular pore structure; and d) supplying a predetermined solution to the separation membrane, thereby introducing functional groups into the pores of the separation membrane exiting the surface layer of the intermediate membrane. The intermediate membrane is impermeable to both the precursor solution used in step c) for forming the separation membrane and the predetermined solution used in step d).

[0018] The above-described objectives, as well as other objectives, features, solutions, and advantages, will become clear from the following detailed description of the invention with reference to the accompanying drawings. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of the separation membrane complex.

[0020] Figure 2 This is a magnified cross-sectional view showing a portion of the separation membrane complex.

[0021] Figure 3 This is a diagram illustrating the manufacturing process of the separation membrane complex.

[0022] Figure 4 This is a diagram showing the separation device.

[0023] Figure 5 It is a diagram showing the separation process of a mixture. Detailed Implementation

[0024] Figure 1 This is a cross-sectional view of the separation membrane complex 1. Figure 2 This is a cross-sectional view showing a portion of the separation membrane composite 1. The separation membrane composite 1 includes: a porous support 11 and a laminated membrane 10 disposed on the support 11. Figure 1 In the image, the laminated membrane 10 is depicted with thick lines. The laminated membrane 10 includes an intermediate membrane 12 and a separation membrane 13. The intermediate membrane 12 is disposed on the support 11, and the separation membrane 13 is disposed on the intermediate membrane 12. Figure 2 In the diagram, parallel oblique lines are used to mark the intermediate membrane 12 and the separation membrane 13. Additionally, Figure 2 In the text, the thickness of the intermediate membrane 12 and the separation membrane 13 is depicted as thicker than they actually are.

[0025] The support 11 is a porous component that allows gas and liquid to pass through. Figure 1In the example shown, the support 11 is: a columnar body integrally formed and connected, with supports respectively arranged along the length direction (i.e., Figure 1 An integral support body with multiple through holes 111 extending in the left and right directions. Figure 1 In the example shown, the support 11 is generally cylindrical. The cross-section of each through hole 111 (i.e., compartment) perpendicular to the length direction is, for example, generally circular. Figure 1 In the diagram, the diameter of the through hole 111 is depicted as larger than it actually is, and the number of through holes 111 is depicted as fewer than it actually is. A laminated film 10 is formed on the inner circumferential surface of the through hole 111, covering the inner circumferential surface of the through hole 111 substantially entirely.

[0026] The length of the support 11 (i.e., Figure 1 The length (in the left-right direction) is, for example, 10cm to 200cm. The outer diameter of the support 11 is, for example, 0.5cm to 30cm. The distance between the central axes of adjacent through holes 111 is, for example, 0.3mm to 10mm. The surface roughness (Ra) of the support 11 is, for example, 0.1μm to 5.0μm, preferably 0.2μm to 2.0μm. It should be noted that the shape of the support 11 can be, for example, honeycomb, flat, tubular, cylindrical, prismatic, or polygonal. When the shape of the support 11 is tubular or cylindrical, the thickness of the support 11 is, for example, 0.1mm to 10mm.

[0027] The material of the support 11 only needs to be chemically stable during the process of forming the laminated film 10 on the surface, and various substances (such as ceramics or metals) can be used. In this embodiment, the support 11 is formed from a ceramic sintered body. Examples of ceramic sintered bodies selected as the material of the support 11 include: alumina, silicon dioxide, andalusite, zirconium dioxide, titanium dioxide, yttrium oxide, silicon nitride, and silicon carbide. In this embodiment, the support 11 includes at least one of alumina, silicon dioxide, andalusite.

[0028] The support 11 may contain an inorganic binder. As an inorganic binder, at least one of the following can be used: titanium dioxide, andalusite, easily sinterable alumina, silica, glass frit, clay minerals, and easily sinterable cordierite.

[0029] The average pore size of the support 11 is, for example, 0.01 μm to 70 μm, preferably 0.05 μm to 25 μm. The average pore size of the support 11 near the surface of the laminated film 10 to be formed is 0.01 μm to 1 μm, preferably 0.05 μm to 0.5 μm. For example, the average pore size can be measured using a mercury porosimeter, a pore size distribution measuring instrument, or a nanoscale pore size distribution measuring instrument. Regarding the overall pore size distribution of the support 11, including the surface and interior, D5 is, for example, 0.01 μm to 50 μm, D50 is, for example, 0.05 μm to 70 μm, and D95 ​​is, for example, 0.1 μm to 2000 μm. The porosity of the support 11 near the surface of the laminated film 10 to be formed is, for example, 20% to 60%.

[0030] The support 11 has, for example, a multilayer structure in which multiple layers with different average pore sizes are stacked along the thickness direction. The average pore size and sintered grain size of the surface layer, including the surface of the laminated film 10 to be formed, are smaller than the average pore size and sintered grain size of the layers other than the surface layer. The average pore size of the surface layer of the support 11 is, for example, 0.01 μm to 1 μm, preferably 0.05 μm to 0.5 μm. When the support 11 has a multilayer structure, the material of each layer can be the material described above. The materials of the multiple layers forming the multilayer structure can be the same or different.

[0031] As described above, the laminated membrane 10 includes: an intermediate membrane 12 disposed on the surface of the support 11, and a separation membrane 13 disposed on the intermediate membrane 12. The intermediate membrane 12 is a polycrystalline membrane and is a porous membrane with fine pores (micropores) having a framework structure derived from crystallization. The intermediate membrane 12 is, for example, a membrane formed from zeolite or a metal-organic framework (MOF). A membrane formed from zeolite or MOF means a membrane obtained by forming zeolite or MOF in a film form at least on the surface of the support 11, excluding membranes obtained by simply dispersing zeolite or MOF particles in an organic membrane. The intermediate membrane 12 can be formed from substances other than zeolite and MOF.

[0032] The thickness of the intermediate membrane 12 is, for example, 0.05 μm to 30 μm. The thickness of the intermediate membrane 12 is preferably 5 μm or less, more preferably 4 μm or less, and even more preferably 3 μm or less. The thickness of the intermediate membrane 12 is preferably 0.1 μm or more, more preferably 0.5 μm or more. For example, the thickness of the intermediate membrane 12 can be determined by photographing a cross-section perpendicular to the intermediate membrane 12 using a scanning electron microscope (SEM) or a field emission scanning electron microscope (FE-SEM) (the thickness of the separation membrane 13 described later is also determined in the same way).

[0033] The average pore size of the intermediate membrane 12 is preferably 1.0 nm or less, more preferably 0.8 nm or less, and even more preferably 0.6 nm or less. The average pore size of the intermediate membrane 12 is preferably 0.1 nm or more, more preferably 0.2 nm or more, and even more preferably 0.3 nm or more. The average pore size of the intermediate membrane 12 is smaller than the average pore size of the support 11 near the surface of the intermediate membrane 12 to be formed. In the manufacturing of the separation membrane composite 1 described later, if the precursor solution for forming the separation membrane 13 does not permeate the intermediate membrane 12, the average pore size of the intermediate membrane 12 can be greater than 1.0 nm.

[0034] The preferred intermediate membrane 12 is a membrane formed of zeolite. When the maximum number of ring elements in the zeolite is n, the arithmetic mean of the minor and major axes of the n-membered ring pores is taken as the average pore diameter. An n-membered ring pore refers to a pore in which n oxygen atoms are bonded to T atoms to form a ring structure. When the zeolite has multiple types of n-membered ring pores with the same number of atoms, the arithmetic mean of the minor and major axes of all types of n-membered ring pores is taken as the average pore diameter of the zeolite. In this way, the average pore diameter of the zeolite membrane can be uniquely determined by the zeolite's skeletal structure and can be calculated using values ​​published in the International Zeolite Society's "Database of Zeolite Structures" [online], URL <URL: http: / / www.iza-structure.org / databases / >.

[0035] The type of zeolite constituting the intermediate film 12 is not particularly limited, and can be, for example, AEI type, AEN type, AFN type, AFV type, AFX type, BEA type, CHA type, DDR type, ERI type, ETL type, FAU type (X type, Y type), GIS type, LEV type, LTA type, MEL type, MER type, MFI type, MOR type, PAU type, RHO type, SAT type, SOD type, SZR type, etc. The intermediate film 12 is, for example, a DDR type zeolite. In other words, the intermediate film 12 is a zeolite film composed of zeolite with a structure code of "DDR" as specified by the International Zeolite Society. In this case, the inherent pore size of the zeolite constituting the intermediate film 12 is 0.36 nm × 0.44 nm, and the average pore size is 0.40 nm.

[0036] When the intermediate film 12 is a zeolite film, the intermediate film 12 contains, for example, silicon (Si). The intermediate film 12 may contain any two or more of, for example, Si, aluminum (Al), and phosphorus (P). In this case, the zeolite constituting the intermediate film 12 may be: a zeolite in which the atom (T atom) at the center of the oxygen tetrahedron (TO4) constituting the zeolite is only Si; or a zeolite in which the T atom contains Si and Al; an AlPO-type zeolite in which the T atom contains Al and P; a SAPO-type zeolite in which the T atom contains Si, Al, and P; a MAPSO-type zeolite in which the T atom contains magnesium (Mg), Si, Al, and P; or a ZnAPSO-type zeolite in which the T atom contains zinc (Zn), Si, Al, and P, etc. A portion of the T atom may be replaced by other elements.

[0037] When the intermediate film 12 contains both Si and Al atoms, the Si / Al ratio in the intermediate film 12 is, for example, 1 or more and less than 100,000. This Si / Al ratio is preferably 5 or more, more preferably 20 or more, and even more preferably 100 or more; the higher the ratio, the better. The Si / Al ratio in the intermediate film 12 can be adjusted by adjusting the proportions of the Si source and Al source in the raw material solution described later. The intermediate film 12 may contain an alkali metal. This alkali metal is, for example, sodium (Na) or potassium (K).

[0038] When the intermediate film 12 is a film formed of MOF, the average pore size of the intermediate film 12 can also be calculated based on the crystalline framework structure. There are no particular limitations on the type of MOF constituting the intermediate film 12 or the elements constituting the MOF.

[0039] The separation membrane 13 is an inorganic membrane with a regular microporous structure. A regular microporous structure typically exhibits a micropore size distribution with a substantially uniform pore size, preferably a micropore size distribution within a narrow range of 0.5–10 nm (e.g., a micropore size distribution in which more than 90% of the pores are contained within this range). The separation membrane 13 is, for example, a membrane formed from mesoporous materials, zeolites, or MOFs. A membrane formed from mesoporous materials, zeolites, or MOFs refers to a membrane obtained by forming mesoporous materials, zeolites, or MOFs in a membrane-like form at least on the intermediate membrane 12, excluding membranes obtained by simply dispersing particles of mesoporous materials, zeolites, or MOFs in an organic membrane. The separation membrane 13 can be formed from substances other than mesoporous materials, zeolites, and MOFs. The separation membrane 13 can be used as a membrane for separating a specific substance from a mixture containing multiple types of substances using molecular sieving. In the separation membrane 13, other substances are less likely to permeate compared to the specific substance. In other words, the permeation rate of the other substance through the separation membrane 13 is less than the permeation rate of the specific substance mentioned above.

[0040] For example, the thickness of the separation membrane 13 is less than the thickness of the intermediate membrane 12. The thickness of the separation membrane 13 may also be greater than or equal to the thickness of the intermediate membrane 12. The thickness of the separation membrane 13 is preferably 1 μm or less, more preferably 0.5 μm or less, and even more preferably 0.3 μm or less. If the separation membrane 13 is made thinner, the permeation rate of the aforementioned specific substance will increase. The thickness of the separation membrane 13 is preferably 0.1 μm or more, more preferably 0.2 μm or more. If the separation membrane 13 is made thicker, the separation performance will improve. The surface roughness (Ra) of the separation membrane 13 is, for example, 1 μm or less, preferably 0.5 μm or less, and more preferably 0.3 μm or less.

[0041] The average pore size of the separation membrane 13 is preferably 10.0 nm or less, more preferably 8.0 nm or less, and even more preferably 5.0 nm or less. The average pore size of the separation membrane 13 is preferably 0.5 nm or more, more preferably 1.0 nm or more, and even more preferably 2.0 nm or more. For example, the average pore size of the separation membrane 13 is larger than the average pore size of the intermediate membrane 12. The average pore size of the separation membrane 13 may also be less than or equal to the average pore size of the intermediate membrane 12.

[0042] The preferred separation membrane 13 is an amorphous membrane formed of oxides such as mesoporous silica or mesoporous carbon. Since the mesoporous silica or mesoporous carbon is formed using surfactant micelles as templates, the average pore size can be determined depending on the type of surfactant used. The average pore size is the arithmetic mean of the minor and major diameters of the pores. In the case where the separation membrane 13 is formed of mesoporous silica or mesoporous carbon, the average pore size is, for example, 0.5 nm to 10.0 nm. The average pore size of the separation membrane 13 can be measured using transmission electron microscopy (TEM).

[0043] When the separation membrane 13 is mesoporous silica or mesoporous carbon, the X-ray diffraction (XRD) pattern obtained by irradiating the surface of the separation membrane 13 with X-rays shows peaks originating from the regular fine pore structure of the separation membrane 13 within the diffraction angle range of 2θ = 1 to 4°. In other words, the presence of peaks in the X-ray diffraction pattern within the range of 2θ = 1 to 4° indicates that the separation membrane 13 has a regular fine pore structure of preferred size. It should be noted that, for example, CuKα rays are used as the X-ray source in the X-ray diffraction device for obtaining the X-ray diffraction pattern.

[0044] The separation membrane 13 can also be a membrane in which no peaks appear in the X-ray diffraction pattern in the range of 2θ = 1 to 4°. For example, in the case where the separation membrane 13 is a membrane formed of zeolite or MOF, typically, the aforementioned peaks do not appear in the X-ray diffraction pattern. The separation membrane 13, as a zeolite membrane or MOF membrane, is a polycrystalline membrane with fine pores derived from a skeletal structure of crystallization. It can be said that such a separation membrane 13 is also a membrane with a generally uniform pore size and a regular pore structure.

[0045] On the surface layer 14 of the separation membrane 13, which is separated from the intermediate membrane 12, the surface of the pores is modified using functional groups that adsorb a specified substance (e.g., CO2). That is, the surface layer 14, including the surface of the separation membrane 13, becomes a functional group introduction layer 14 in which functional groups are introduced into the pores. The functional group introduction layer 14 can also be referred to as an organic-inorganic mixed layer in which functional groups of organic matter are incorporated into the separation membrane 13, which is an inorganic membrane. The functional groups introduced into the functional group introduction layer 14 are, for example, amino groups. Figure 2 In the diagram, the functional group introduction layer 14 within the separation membrane 13 is marked with a parallel oblique line that intersects the parallel oblique line of the separation membrane 13.

[0046] In the separation membrane 13, the functional group introduction layer 14 is only disposed on the surface side of the separation membrane 13, and not on the intermediate membrane 12 side. In other words, in the separation membrane 13, the functional group introduction layer 14 (functional groups) exists in a state biased towards the surface side. The reason for forming such a functional group introduction layer 14 is not yet clear, but it is believed that one of the reasons is that the solution used for introducing functional groups in the manufacturing of the separation membrane composite 1 described later cannot pass through the pores of the intermediate membrane 12. In the separation membrane, if functional groups are introduced into the overall pores, the substances adsorbed on the functional groups repeatedly undergo adsorption and detachment from the functional groups, thereby passing through the separation membrane. Therefore, the permeation resistance of the substances increases, and the permeation rate decreases. In contrast, in the separation membrane composite 1, the functional group introduction layer 14 is only disposed on the surface side of the separation membrane 13, therefore, the permeation resistance of the substances decreases, and the permeation rate increases.

[0047] For example, the presence of the functional group-introduced layer 14 can be confirmed using D-SIMS (Dynamic-SIMS). Regarding C and H, moisture is detected; however, if it is, for example, an amino-containing silane coupling agent, the loading can be determined by measuring the nitrogen element.

[0048] In D-SIMS, the concentration of an element (hereinafter referred to as "specific element") containing functional groups in the functional group introduction layer 14 but not in the separation membrane 13 (other than the functional group) and the intermediate membrane 12 is measured along the depth direction from the surface of the separation membrane 13. Furthermore, it can be said that the functional group introduction layer 14 is only provided on the surface side of the separation membrane 13 and not on the intermediate membrane 12 side of the separation membrane 13, in the case where the concentration of the specific element gradually decreases (has a gradient) from the surface of the separation membrane 13 towards the intermediate membrane 12, and the concentration of the specific element remains approximately constant until reaching the interface between the separation membrane 13 and the intermediate membrane 12. It should be noted that the concentration of the specific element near the surface of the separation membrane 13 has a contamination effect and can therefore be ignored. If the distance from the surface of the separation membrane 13 to the position where the concentration of the specific element remains approximately constant is defined as the thickness of the functional group introduction layer 14, then the thickness of the functional group introduction layer 14 is preferably 0.7 times or less the thickness of the separation membrane 13, more preferably 0.5 times or less. For example, the thickness of the functional group introduction layer 14 is more than 0.1 times the thickness of the separation membrane 13.

[0049] Next, refer to Figure 3 An example of the manufacturing process for the separation membrane composite 1 will be described below. Hereinafter, an example of forming a zeolite membrane as the intermediate membrane 12 and a mesoporous silica membrane as the separation membrane 13 will be described. However, when forming other types of membranes as the intermediate membrane 12 and the separation membrane 13, the well-known methods for forming such membranes will be used to perform the process. Figure 3 The same treatment applies.

[0050] In the manufacture of the separation membrane composite 1, firstly, a porous support 11 is prepared (step S11). Additionally, seed crystals for manufacturing the zeolite membrane are prepared. In one example where a DDR-type zeolite membrane is formed as the intermediate membrane 12, DDR-type zeolite powder is generated by hydrothermal synthesis, and seed crystals are obtained from this zeolite powder. The zeolite powder can be used directly as seed crystals, or the powder can be processed using methods such as pulverization to obtain seed crystals.

[0051] Next, the support 11 is immersed in a dispersion of seed crystals, causing the seed crystals to adhere to the support 11. Alternatively, the dispersion of seed crystals is brought into contact with a portion of the support 11 where the intermediate film 12 is to be formed, thereby causing the seed crystals to adhere to the support 11. In this way, a seed-attached support is fabricated. Seed crystals can also be attached to the support 11 using other methods.

[0052] The support 11 with seed crystals attached is immersed in a raw material solution. For example, the raw material solution is prepared by dissolving or dispersing a Si source and a structure-directing agent (SDA) in a solvent. The Si source can be, for example, silica gel, sodium silicate, fumed silica, or an alkoxide. The SDA contained in the raw material solution can be, for example, an organic compound. The SDA can be, for example, 1-adamantaneamine. The solvent can be, for example, water. Then, using the seed crystals as nuclei, DDR-type zeolite is grown via hydrothermal synthesis, thereby forming a DDR-type zeolite film on the support 11 as an intermediate film 12. The hydrothermal synthesis temperature is, for example, 80–200°C. The hydrothermal synthesis time is, for example, 3–100 hours.

[0053] After hydrothermal synthesis, the support 11 and the intermediate membrane 12 are washed with pure water. The washed support 11 and intermediate membrane 12 are then dried at, for example, 80°C. After drying, the support 11 and intermediate membrane 12 are heated in an oxidizing gas atmosphere to burn off the SDA in the intermediate membrane 12. This results in interconnected micropores within the intermediate membrane 12. Preferably, approximately complete removal of SDA is achieved. The heating temperature for SDA removal is, for example, 300–700°C. The heating time is, for example, 5–200 hours. The oxidizing gas atmosphere is an oxygen-containing atmosphere, such as atmospheric air.

[0054] Through the above processing, an intermediate film 12 with interconnected micropores is obtained (step S12). The intermediate film 12, as a zeolite film, is a polycrystalline film with micropores originating from the framework structure. The average pore diameter of the intermediate film 12 is smaller than the average pore diameter of the micropores near the surface of the support 11. It should be noted that in the formation of the zeolite film, the process of attaching seed crystals to the support 11 can be omitted; in this case, the zeolite film is formed directly on the support 11.

[0055] Next, a precursor solution for forming the separation membrane 13 is prepared. For example, the precursor solution is prepared by dissolving a silica source, a surfactant, and an acid catalyst in a solvent. The silica source can be, for example, tetraethyl orthosilicate (TEOS) or tetramethyl orthosilicate (TMOS). Examples of surfactants include, for example, bromides or chlorides such as cetyltrimethylammonium bromide (CTAB) and cetyltrimethylammonium chloride; however, the present invention is not limited to these surfactants. The acid catalyst is a pH adjuster, such as hydrochloric acid, nitric acid, or sulfuric acid. A base can also be used as a pH adjuster. The solvent is, for example, an organic solvent such as ethanol or isopropanol (IPA). The proportions of each component in the precursor solution can be appropriately set according to the type of mesoporous silica membrane to be formed.

[0056] The precursor solution is supplied to the intermediate membrane 12 of the support 11. At this time, the intermediate membrane 12 is impermeable to the precursor solution; therefore, the precursor solution does not permeate through the pores of the intermediate membrane 12 but adheres to its surface. That is, a membrane of the precursor solution is formed on the surface of the intermediate membrane 12. Excess precursor solution on the intermediate membrane 12 is preferably removed by, for example, blowing air. By blowing air, the solvent and the like in the precursor solution are also largely removed. Then, the support 11 is heated in an oxidizing gas atmosphere, thereby burning off the surfactant in the membrane on the intermediate membrane 12. Accordingly, a mesoporous silica membrane is formed on the intermediate membrane 12 as a separation membrane 13 (step S13). The separation membrane 13 has a regular pore structure. The heating temperature for surfactant removal is, for example, 300–600°C. The heating time is, for example, 1–100 hours. The oxidizing gas atmosphere is an atmosphere containing oxygen, such as atmospheric air.

[0057] Here, if a separation membrane is formed on a support 11 without an intermediate membrane 12, i.e., if a precursor solution is directly supplied to the support 11, the precursor solution will penetrate into the pores of the support 11 (through the pores). As a result, poor coating will occur on the surface of the support 11 where the separation membrane is to be formed, specifically, areas where a mesoporous silica film (separation membrane) is not formed. In contrast, in Figure 3 In the manufacture of the separation membrane composite 1, the intermediate membrane 12 is used to prevent or inhibit the infiltration of the precursor solution into the pores of the support 11, thereby preventing poor coating caused by the infiltration of the precursor solution and thus enabling the formation of a uniform separation membrane 13.

[0058] When the separation membrane 13 is formed, a solution for introducing functional groups is prepared. This solution is used to introduce a specified functional group, for example, a solution obtained by dissolving a silane coupling agent in a solvent. The solution for introducing functional groups is also called a mixed solution. This functional group adsorbs a specified substance (e.g., CO2), for example, a basic functional group having an amino group. Examples of silane coupling agents include 3-aminopropyltriethoxysilane (APS) and N1-(3-trimethoxysilylpropyl)diethylenetriamine. Examples of substances with basic functional groups other than silane coupling agents include amines. Examples include ethylenediamine, 2-(2-aminoethylamino)ethanol, N-ethylethylenediamine, diethylenetriamine, isobutylamine, N-(2-aminoethyl)piperazine, or polyethyleneimine. Solvents include organic solvents such as toluene, methanol, ethanol, isopropanol, acetone, and THF (tetrahydrofuran).

[0059] A solution for introducing functional groups is supplied to the separation membrane 13. In this example, the support 11 on which the separation membrane 13 is formed is immersed in a solution for introducing functional groups at room temperature, thereby supplying the solution to the separation membrane 13. The immersion time is, for example, 1 to 200 hours. During this time, the solution for introducing functional groups can pass through the pores of the separation membrane 13, but cannot pass through the pores of the intermediate membrane 12. That is, the separation membrane 13 is permeable to the solution for introducing functional groups, while the intermediate membrane 12 is impermeable to the solution for introducing functional groups. Therefore, the solution for introducing functional groups only penetrates into the pores of the separation membrane 13 from the surface side of the separation membrane 13, and does not penetrate into the pores of the separation membrane 13 from the intermediate membrane 12 side (support 11 side). After the immersion time, the support 11 is removed from the solution for introducing functional groups. Accordingly, functional groups are introduced into the pores of the surface layer 14 of the separation membrane 13 away from the intermediate membrane 12 (step S14). That is, the surface layer 14 of the separation membrane 13 was mixed with organic and inorganic materials. Through the above treatment, the manufacturing of the separation membrane composite 1 was completed.

[0060] As explained above, in the separation membrane composite 1, an intermediate membrane 12 is disposed on the surface of a porous support 11, and a separation membrane 13 with a regular microporous structure is disposed on the intermediate membrane 12. The intermediate membrane 12 is a polycrystalline membrane with micropores originating from the framework structure. Furthermore, the average pore diameter of these micropores is smaller than the average pore diameter of the micropores near the surface of the support 11. Therefore, the penetration of the precursor solution for forming the separation membrane into the micropores of the support 11 is prevented or inhibited by the intermediate membrane 12. As a result, defects such as poor coating can be suppressed, and the separation membrane 13 can be appropriately formed on the support 11 (for example, a separation membrane 13 with a thickness of less than 1 μm is uniformly formed). In addition, in the separation membrane 13, which is an inorganic membrane, functional groups for adsorbing a specified substance (e.g., CO2) are introduced into the micropores of the surface layer 14 away from the intermediate membrane 12. In the separation membrane 13, the range of functional groups to be introduced is limited to the surface side, thus enabling high separation performance and increasing the permeation rate of the substance.

[0061] When the functional group is amino, high separation performance can be achieved and the permeation rate of carbon dioxide can be increased. The functional group can be any group other than amino.

[0062] In the preferred separation membrane composite 1, the average pore size of the intermediate membrane 12 is 0.1 nm to 1.0 nm. Accordingly, the intermediate membrane 12 can more reliably prevent or suppress the infiltration of the precursor solution and the permeation of the solution used for functional group introduction. Furthermore, since the average pore size of the separation membrane 13 is 0.5 nm or more, the pores can be modified with a large number of functional groups, achieving a high permeation rate. Moreover, since the average pore size of the separation membrane 13 is 10.0 nm or less, the pores can be modified with functional groups, achieving high separation performance.

[0063] Preferably, the thickness of the intermediate membrane 12 is 5 μm or less, and the thickness of the separation membrane 13 is 1 μm or less. This allows for a more reliable increase in the permeation rate of the specified substance.

[0064] Preferably, the intermediate membrane 12 is a membrane formed of zeolite or a metal-organic structure. Accordingly, it is possible to easily realize an intermediate membrane 12 that is a polycrystalline membrane and has fine pores derived from the framework structure. In addition, the intermediate membrane 12 can more reliably prevent or suppress the penetration of precursor solutions and the permeation of solutions used for introducing functional groups.

[0065] Preferably, the separation membrane 13 is a membrane formed of a mesoporous material, zeolite, or metal-organic structure. Accordingly, a separation membrane 13 with a regular fine pore structure can be easily achieved. Furthermore, in the X-ray diffraction pattern obtained by irradiating the surface of the separation membrane 13 with X-rays, a peak preferably appears in the range of 2θ = 1 to 4°. In this case, it can be said that a preferred separation membrane 13 with a regular fine pore structure has been achieved.

[0066] The method for manufacturing the separation membrane composite 1 includes the following steps: preparing a porous support 11 (step S11); forming an intermediate membrane 12 on the surface of the support 11 (step S12); forming a separation membrane 13 on the intermediate membrane 12 (step S13); and introducing functional groups into the pores of the separation membrane 13 away from the surface layer 14 of the intermediate membrane 12 (step S14). The intermediate membrane 12 is impermeable to the precursor solution used to form the separation membrane 13 in step S13 and the solution used for introducing functional groups in step S14. Accordingly, the separation membrane 13 can be appropriately formed on the porous support 11. In addition, in the separation membrane 13, functional groups are introduced only on the surface side, thereby increasing the permeation rate of a specified substance.

[0067] Next, examples of the separation membrane composites will be described. Table 1 shows the type and thickness of the intermediate membrane, the type and thickness of the separation membrane, the type of basic functional groups, and the measurement results of CO2 permeation rate in Examples 1 to 10 and Comparative Example 1.

[0068] Table 1

[0069]

[0070] <Example 1>

[0071] (Fabrication of the intermediate membrane (DDR type zeolite membrane))

[0072] A monolithic porous alumina support was prepared, with DDR-type zeolite seed crystals attached to the inner circumferential surface of the through-holes. Next, silica gel, 1-adamantaneamine, ethylenediamine, and water were mixed to prepare a raw material solution. The ratio of silica, 1-adamantaneamine, ethylenediamine, and water was 1:1:0.25:100 (molar ratio). The porous alumina support with DDR-type zeolite seed crystals was placed in a fluoropolymer inner cylinder (300 ml) of a stainless steel pressure vessel, and the above raw material solution was placed inside. Heating treatment was then performed (hydrothermal synthesis: 130°C, 24 hours), thereby forming a high-silica DDR-type zeolite film on the inner circumferential surface of the through-holes. Next, the alumina support was cleaned and dried at 80°C for at least 12 hours. Then, the alumina support was heated to 450°C in an electric furnace and held for 50 hours to burn off organic matter (SDA), obtaining the DDR-type zeolite film as the intermediate film.

[0073] (Fabrication of the separation membrane (mesoporous silica membrane))

[0074] Prepare the following: tetraethyltriethoxysilane (hereinafter referred to as "TEOS") as the silica source, hexadecylmethylammonium bromide (hereinafter referred to as "CTAB") as the surfactant, hydrochloric acid as the acid catalyst, and ethanol (EtOH) as the solvent. Mix TEOS and ethanol, add water adjusted to pH = 1.25 using hydrochloric acid, and perform hydrolysis. Then, add CTAB and disperse it using an ultrasonic cleaner. Next, add more ethanol to prepare a precursor solution with a molar ratio of 1 SiO2:0.1 CTAB:5 H2O:11.8 EtOH.

[0075] For an integral porous support with a zeolite membrane, a precursor solution is allowed to flow into the inner circumferential surface of the through-pores. Excess precursor solution is then blown away using air. The porous support is heated to 450°C in an electric furnace and held for 50 hours to burn off CTAB, resulting in a separation membrane composite with a mesoporous silica membrane forming on the zeolite membrane.

[0076] (Organic-inorganic hybridization of separation membranes)

[0077] A solution for introducing functional groups was prepared by mixing 3-aminopropyltriethoxysilane (APS), which serves as a silane coupling agent, and toluene. The aforementioned separation membrane complex was then immersed in this solution and kept at room temperature for 24 hours.

[0078] <Example 2>

[0079] The silane coupling agent was changed to N1-(3-trimethoxysilylpropyl)diethylenetriamine, otherwise it was the same as in Example 1.

[0080] <Example 3>

[0081] The basic functional group was replaced with ethylenediamine, otherwise it was the same as in Example 1.

[0082] <Example 4>

[0083] The basic functional group was changed to 2-(2-aminoethylamino)ethanol, otherwise it was the same as in Example 1.

[0084] <Example 5>

[0085] The intermediate membrane was changed to an MFI type zeolite membrane, otherwise it was the same as in Example 1.

[0086] (Preparation of the intermediate membrane (MFI type zeolite membrane))

[0087] A monolithic porous alumina support was prepared, with MFI-type zeolite seed crystals attached to the inner circumferential surface of the through-holes. Next, a raw material solution was prepared by mixing silica, tetrapropylammonium bromide, and water. The ratio of silica, tetrapropylammonium bromide, and water was 1:0.25:100 (molar ratio). The porous alumina support with attached MFI-type zeolite seed crystals was placed in a fluoropolymer inner cylinder (300 ml) of a stainless steel pressure vessel, and the above raw material solution was placed inside. Heating treatment was then performed (hydrothermal synthesis: 160°C, 24 hours), thereby forming a high-silica MFI-type zeolite film on the inner circumferential surface of the through-holes. Next, the alumina support was cleaned and dried at 80°C for at least 12 hours. Then, the alumina support was heated to 450°C in an electric furnace and held for 50 hours to burn off the organic matter (SDA), obtaining the MFI-type zeolite film as the intermediate film.

[0088] <Example 6>

[0089] The basic functional group was changed to 2-(2-aminoethylamino)ethanol, otherwise it was the same as in Example 5.

[0090] <Example 7>

[0091] The intermediate membrane was changed to a BEA-type zeolite membrane, otherwise it was the same as in Example 1.

[0092] (Preparation of the intermediate membrane (BEA-type zeolite membrane))

[0093] A monolithic porous alumina support was prepared, with BEA-type zeolite seed crystals attached to the inner circumferential surface of the through-pores. Next, a raw material solution was prepared by mixing silica, tetraethylammonium hydroxide, hydrofluoric acid, and water. The ratio of silica, tetraethylammonium hydroxide, hydrofluoric acid, and water was 1:0.5:0.5:20 (molar ratio). The porous alumina support with attached BEA-type zeolite seed crystals was placed inside a fluoropolymer inner cylinder (300 ml) of a stainless steel pressure vessel, and the above raw material solution was placed in it. Heating treatment was then performed (hydrothermal synthesis: 130°C, 96 hours), thereby forming a high-silica BEA-type zeolite film on the inner circumferential surface of the through-pores. Next, the alumina support was cleaned and dried at 80°C for at least 12 hours. Subsequently, the alumina support was heated to 450°C in an electric furnace and held for 50 hours to burn off the organic matter (SDA), thereby obtaining the BEA-type zeolite membrane as the intermediate membrane.

[0094] <Example 8>

[0095] The intermediate membrane was changed to a FAU-type zeolite membrane, and the combustion removal conditions of CTAB during the fabrication of the mesoporous silica membrane were changed to 300°C × 100h. Otherwise, it was the same as in Example 1.

[0096] (Preparation of the intermediate membrane (FAU-type zeolite membrane))

[0097] A monolithic porous alumina support was prepared, with FAU-type zeolite seed crystals attached to the inner circumferential surface of the through-pores. Next, a raw material solution was prepared by mixing silica, sodium hydroxide, aluminum hydroxide, and water. The ratio of aluminum hydroxide, silica, sodium hydroxide, and water was 1:10:40:200 (molar ratio). The porous alumina support with attached FAU-type zeolite seed crystals was placed inside a fluoropolymer inner cylinder (300 ml) of a stainless steel pressure vessel, and the above raw material solution was placed in it. Heating treatment was then performed (hydrothermal synthesis: 80°C, 10 hours), thereby forming a high-silica FAU-type zeolite film on the inner circumferential surface of the through-pores. Afterwards, the alumina support was cleaned and dried at 80°C for at least 12 hours.

[0098] <Example 9>

[0099] The intermediate membrane (DDR-type zeolite membrane) was prepared in the same manner as in Example 1, except that the basic functional group was changed to diethylenetriamine and the solvent was changed to water. In addition, the temperature for organic-inorganic mixing was set to 80°C.

[0100] <Example 10>

[0101] The intermediate membrane was changed to a MOF (UiO-66) membrane, and the combustion removal conditions of CTAB during the fabrication of the mesoporous silica membrane were changed to 300°C × 100h. Otherwise, it was the same as in Example 1.

[0102] (Fabrication of intermediate membrane (MOF(UiO-66) membrane))

[0103] ZrCl4, 1,4-phthalic acid, water, and acetic acid were added to DMF (dimethylformamide). The ratio of ZrCl4, 1,4-phthalic acid, water, acetic acid, and DMF was 1:1:1:100:200 (molar ratio). The mixture was allowed to stand at 120°C for 24 hours. After cooling, the mixture was washed with DMF to obtain the target compound.

[0104] Water was added to the obtained UiO-66 to adjust it to a 0.05 wt% aqueous solution, and then the mixture was pulverized using a ball mill for one day. A monolithic porous alumina support was prepared by attaching UiO-66 seed crystals to the inner circumferential surface of the through-holes. ZrCl4, 1,4-phthalic acid, water, and acetic acid were added to DMF, and the support was immersed in a solution containing ZrCl4, 1,4-phthalic acid, water, acetic acid, and DMF in a molar ratio of 1:1:1:100:600 at 130°C for 6 hours. After immersion, the support was washed sequentially with DMF and water.

[0105] <Comparative Example 1>

[0106] No zeolite membrane as an intermediate membrane was formed, except that it was the same as in Example 1.

[0107] Next, various measurements and evaluations were performed on the separation membrane complexes of Examples 1 to 10 and Comparative Example 1.

[0108] (Thickness measurement of intermediate membrane and separation membrane)

[0109] The thicknesses of the zeolite membrane (intermediate membrane) and the mesoporous silica membrane (separation membrane) were measured using a scanning electron microscope (SEM) to photograph a cross-section perpendicular to the membranes. In the separation membrane composites of Examples 1 to 10, a uniform mesoporous silica membrane with a thickness of 0.3 μm was formed. On the other hand, in the separation membrane composite of Comparative Example 1, the precursor solution permeated into the pores of the support, and no membrane formed on the support surface, resulting in poor coating of the mesoporous silica membrane.

[0110] (X-ray diffraction evaluation)

[0111] In the X-ray diffraction (XRD) evaluation, a Rigaku MiniFlex 600 X-ray diffraction apparatus was used. X-ray diffraction measurements were performed with a tube voltage of 40 kV, a tube current of 15 mA, a scan speed of 0.5° / min, and a scan step of 0.02°. The divergence slit was set to 1.25°, the scattering slit to 1.25°, the receiving slit to 0.3 mm, the incident slit to 5.0°, and the receiving slit to 5.0°. No monochromator was used; a 0.015 mm thick nickel foil was used as a CuK beta-ray filter. The surface of the mesoporous silica film was irradiated with X-rays after the separation membrane composite was cut along a plane including the central axis of any through-hole.

[0112] In the X-ray diffraction patterns obtained from the separation membrane composites of Examples 1 to 10, peaks originating from mesoporous silica films could be identified near 2θ = 3°, and peaks originating from zeolite films or MOF films could be identified beyond 5°. In the X-ray diffraction pattern obtained from the separation membrane composite of Comparative Example 1, diffraction peaks originating from fine pores could not be identified in the range of 1 to 4°.

[0113] (D-SIMS evaluation)

[0114] In the separation membrane composites of Examples 1 to 10, the surface of the mesoporous silica membrane was measured using D-SIMS. The results showed that the concentration of nitrogen (N) in the silane coupling agent gradually decreased from the surface of the mesoporous silica membrane towards the zeolite membrane (exhibiting a gradient), remaining approximately constant before reaching the interface with the zeolite membrane. In the separation membrane composites of Examples 1 to 10, a mesoporous silica membrane was formed on either the zeolite membrane or the MOF membrane. Therefore, it is presumed that during mixing, excessive penetration of the functional group-introducing solution into the pores of the mesoporous silica membrane was suppressed, thereby increasing the nitrogen concentration only at the surface of the mesoporous silica membrane. In the separation membrane composite of Comparative Example 1, nitrogen was detected unevenly throughout the entire support, suggesting that the functional group-introducing solution penetrated throughout the entire support.

[0115] (Membrane performance evaluation)

[0116] Carbon dioxide (CO2) gas was introduced into the surface of a mesoporous silica membrane at 100°C and a pressure of 0.3 MPa, and the CO2 permeation rate was measured. Compared with the separation membrane composite of Comparative Example 1, the separation membrane composites of Examples 1 to 10 achieved sufficiently high CO2 permeation rates.

[0117] Next, refer to Figure 4 and Figure 5 The separation of mixed substances using separation membrane complex 1 is explained. Figure 4 This is a diagram showing the separation device 2. Figure 5This is a diagram illustrating the process of separating mixed substances using separation device 2.

[0118] In the separation device 2, a mixture containing multiple types of fluids (i.e., gases or liquids) is supplied to the separation membrane composite 1, causing highly permeable substances in the mixture to permeate through the separation membrane composite 1, thereby separating them from the mixture. The purpose of separation in the separation device 2 can be, for example, to extract highly permeable substances from the mixture, or to concentrate substances with low permeability.

[0119] The mixture (i.e., the mixed fluid) can be a mixture of gases containing multiple types of gases, a mixture of liquids containing multiple types of liquids, or a gas-liquid two-phase fluid that contains both gases and liquids.

[0120] The mixture contains one or more of the following: hydrogen (H2), helium (He), nitrogen (N2), oxygen (O2), water (H2O), water vapor (H2O), carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides, ammonia (NH3), sulfur oxides, hydrogen sulfide (H2S), sulfur fluoride, mercury (Hg), arsine (AsH3), hydrogen cyanide (HCN), carbonyl sulfide (COS), C1-C8 hydrocarbons, organic acids, alcohols, thiols, esters, ethers, ketones, and aldehydes.

[0121] Nitrogen oxides are compounds of nitrogen and oxygen. The nitrogen oxides mentioned above include, for example, nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide (also known as dinitrogen monoxide) (N2O), dinitrogen trioxide (N2O3), dinitrogen tetroxide (N2O4), and dinitrogen pentoxide (N2O5), etc., collectively referred to as NO. X (Nox) gas.

[0122] Sulfur oxides are compounds of sulfur and oxygen. The sulfur oxides mentioned above include, for example, sulfur dioxide (SO2) and sulfur trioxide (SO3), collectively referred to as SO42-SO ... X (Sox) gas.

[0123] Sulfur fluorides are compounds of fluorine and sulfur. Examples of sulfur fluorides include: disulfur difluoride (F-S-S-F, S=SF2), sulfur difluoride (SF2), sulfur tetrafluoride (SF4), sulfur hexafluoride (SF6), or disulfur decafluoride (S2F). 10 )wait.

[0124] Hydrocarbons with C1 to C8 carbon atoms are hydrocarbons with one or more but less than eight carbon atoms. Hydrocarbons with C3 to C8 carbon atoms can be any of the following: straight-chain compounds, side-chain compounds, and cyclic compounds. In addition, hydrocarbons with C2 to C8 carbon atoms can be any of the following: saturated hydrocarbons (i.e., hydrocarbons without double or triple bonds in the molecule) and unsaturated hydrocarbons (i.e., hydrocarbons with double and / or triple bonds in the molecule). Hydrocarbons with C1 to C4 carbon atoms include, for example, methane (CH4), ethane (C2H6), ethylene (C2H4), propane (C3H8), propylene (C3H6), n-butane (CH3(CH2)2CH3), isobutane (CH(CH3)3), 1-butene (CH2=CHCH2CH3), 2-butene (CH3CH=CHCH3), or isobutene (CH2=C(CH3)2).

[0125] The organic acids mentioned above are carboxylic acids or sulfonic acids, etc. Carboxylic acids include, for example, formic acid (CH₂O₂), acetic acid (C₂H₄O₂), oxalic acid (C₂H₂O₄), acrylic acid (C₃H₄O₂), or benzoic acid (C₆H₅COOH), etc. Sulfonic acids include, for example, ethanesulfonic acid (C₂H₆O₃S), etc. These organic acids can be chain compounds or cyclic compounds.

[0126] The alcohols mentioned above are, for example, methanol (CH3OH), ethanol (C2H5OH), isopropanol (2-propanol) (CH3CH(OH)CH3), ethylene glycol (CH2(OH)CH2(OH)) or butanol (C4H9OH), etc.

[0127] Thiols are organic compounds with hydrogenated sulfur (SH) at their terminals, and are also known as Thiol or Thioalcohol. Examples of thiols include methanethiol (CH3SH), ethanethiol (C2H5SH), and 1-propanethiol (C3H7SH).

[0128] The esters mentioned above are, for example, formate esters or acetate esters.

[0129] The ethers mentioned above are, for example, dimethyl ether ((CH3)2O), methyl ethyl ether (C2H5OCH3), or diethyl ether ((C2H5)2O), etc.

[0130] The ketones mentioned above are, for example, acetone ((CH3)2CO), methyl ethyl ketone (C2H5COCH3), or diethyl ketone ((C2H5)2CO), etc.

[0131] The aldehydes mentioned above include, for example, acetaldehyde (CH3CHO), propionaldehyde (C2H5CHO), or butyraldehyde (C3H7CHO).

[0132] In the following description, we will take as an example a mixture of gases containing multiple types of gases that are separated by the separation device 2.

[0133] The separation device 2 includes: a separation membrane composite 1, a sealing part 21, a housing 22, two sealing components 23, a supply part 26, a first recovery part 27, and a second recovery part 28. The separation membrane composite 1, the sealing part 21, and the sealing components 23 are housed within the housing 22. The supply part 26, the first recovery part 27, and the second recovery part 28 are disposed outside the housing 22 and connected to the housing 22.

[0134] The sealing part 21 is: installed in the longitudinal direction of the support 11 (i.e., Figure 4 The sealing part 21 is a component that seals the two ends of the support body 11 in the left-right direction and covers the two end faces and the outer peripheral surfaces near the two end faces in the longitudinal direction. The sealing part 21 is used to prevent gas from flowing in and out relative to the two end faces of the support body 11. The sealing part 21 is, for example, a plate-shaped component made of glass or resin. The material and shape of the sealing part 21 can be appropriately changed. It should be noted that the sealing part 21 is provided with multiple openings that overlap with the multiple through holes 111 of the support body 11. Therefore, the two ends in the longitudinal direction of each through hole 111 of the support body 11 are not covered by the sealing part 21. Therefore, gas and the like can flow in and out from the two ends relative to the through holes 111.

[0135] The shape of the outer casing 22 is not limited; for example, it may be a generally cylindrical cylindrical component. The outer casing 22 is formed of, for example, stainless steel or carbon steel. The length direction of the outer casing 22 is generally parallel to the length direction of the separation membrane composite 1. At one end of the outer casing 22 in the length direction (i.e., Figure 4 A supply port 221 is provided at the left end of the housing 22, and a first discharge port 222 is provided at the other end. A second discharge port 223 is provided on the side of the housing 22. A supply unit 26 is connected to the supply port 221. A first recovery unit 27 is connected to the first discharge port 222. A second recovery unit 28 is connected to the second discharge port 223. The internal space of the housing 22 is a sealed space isolated from the space surrounding the housing 22.

[0136] Two sealing components 23 are disposed circumferentially between the outer peripheral surface of the separation membrane composite 1 and the inner peripheral surface of the housing 22, near both ends along the length of the separation membrane composite 1. Each sealing component 23 is a generally annular component formed of a gas-impermeable material. The sealing component 23 is, for example, an O-ring formed of a flexible resin. The sealing components 23 are in close contact with the outer peripheral surface of the separation membrane composite 1 and the inner peripheral surface of the housing 22 throughout their circumference. Figure 4In the example shown, the sealing member 23 is in close contact with the outer peripheral surface of the sealing portion 21, and indirectly in close contact with the outer peripheral surface of the separation membrane composite 1 through the sealing portion 21. The sealing member 23 is sealed between the outer peripheral surface of the separation membrane composite 1 and between the sealing member 23 and the inner peripheral surface of the housing 22, so that gas can hardly or completely not pass through.

[0137] The supply unit 26 supplies the mixed gas to the interior space of the housing 22 via the supply port 221. The supply unit 26 includes, for example, a blower or pump that pressurizes the mixed gas toward the housing 22. The blower or pump includes a pressure regulating unit that regulates the pressure of the mixed gas supplied to the housing 22. The first recovery unit 27 and the second recovery unit 28 include, for example, a storage container for storing the gas discharged from the housing 22 or a blower or pump for transferring the gas.

[0138] When performing mixed gas separation, the separation apparatus 2 described above is prepared, thereby preparing the separation membrane composite 1 (step S31). Next, using the supply unit 26, a mixed gas containing multiple gases with different permeability to the laminated membrane 10 (actually, adsorption to the functional groups introduced into the separation membrane 13) is supplied to the interior space of the housing 22. For example, the main components of the mixed gas are CO2 and CH4. The mixed gas may contain gases other than CO2 and CH4. The pressure (i.e., the introduction pressure) of the mixed gas supplied from the supply unit 26 to the interior space of the housing 22 is, for example, 0.1 MPa to 20.0 MPa. The temperature for performing mixed gas separation is, for example, 10°C to 150°C.

[0139] As shown by arrow 251, the mixed gas supplied from the supply unit 26 to the housing 22 is introduced into each through hole 111 of the support 11 from the left end of the separation membrane composite 1 in the figure. A gas with higher permeability (e.g., CO2, hereinafter referred to as "highly permeable substance") in the mixed gas permeates through the laminated membrane 10 and the support 11 disposed on the inner peripheral surface of each through hole 111, and is thus exited from the outer peripheral surface of the support 11. Accordingly, the highly permeable substance is separated from the less permeable gas (e.g., CH4, hereinafter referred to as "lowly permeable substance") in the mixed gas (step S32). The gas exited from the outer peripheral surface of the support 11 (hereinafter referred to as "permeable substance") is recovered via the second outlet 223 using the second recovery unit 28, as shown by arrow 253. The pressure (i.e., permeation pressure) of the gas recovered via the second outlet 223 using the second recovery unit 28 is, for example, approximately 1 atmosphere (0.101 MPa).

[0140] In addition, gases in the mixed gas other than those permeating through the laminated membrane 10 and the support 11 (hereinafter referred to as "impermeable substances") pass through the through holes 111 of the support 11 from left to right in the figure, as shown by arrow 252, and are recovered by the first recovery unit 27 via the first outlet 222. The pressure of the gas recovered by the first recovery unit 27 via the first outlet 222 is, for example, approximately the same as the inlet pressure. In addition to the low-permeability substances described above, the impermeable substances may also include high-permeability substances that do not permeate through the laminated membrane 10.

[0141] The above-mentioned separation membrane composite 1 and the manufacturing method of separation membrane composite 1 can be modified in various ways.

[0142] In the separation membrane composite 1, the average pore size of the intermediate membrane 12 can be greater than 1.0 nm. The average pore size of the separation membrane 13 can be less than 0.5 nm or greater than 10.0 nm. The thickness of the intermediate membrane 12 can be greater than 5 μm, and the thickness of the separation membrane 13 can be greater than 1 μm.

[0143] In the support 11 with through holes, the laminated membrane 10 can be disposed on either the inner peripheral surface or the outer peripheral surface, or on both the inner peripheral surface and the outer peripheral surface.

[0144] The separation membrane composite 1 can be manufactured using methods other than those described above.

[0145] According to the separation device 2 and the separation method, substances other than those exemplified in the above description can be separated from the mixture.

[0146] The components in the above-described embodiments and their variations can be appropriately combined as long as they do not contradict each other.

[0147] Although the invention has been described and illustrated in detail, the above description is illustrative and not limiting. Therefore, it can be said that various modifications or methods can be adopted without departing from the scope of the invention.

[0148] Industrial availability

[0149] The separation membrane composite of the present invention can be used, for example, as a separation membrane for carbon dioxide, and can also be used in various fields as a separation membrane for various substances other than carbon dioxide, an adsorption membrane for various substances, etc.

[0150] Symbol Explanation

[0151] 1 Separation Membrane Complex

[0152] 11 Supports

[0153] 12 Intermediate Membrane

[0154] 13 Separation Membrane

[0155] 14 Functional Group Introduction Layer

[0156] Steps S11~S14, S31, S32

Claims

1. A separation membrane composite, wherein, The separation membrane composite comprises: Porous supports; The intermediate film is a polycrystalline film disposed on the surface of the support and has pores originating from the skeleton structure. The average pore diameter of the pores is smaller than the average pore diameter of the pores near the surface of the support. as well as The separation membrane is an inorganic membrane with a regular fine pore structure disposed on the intermediate membrane. Functional groups are introduced into the pores of the surface layer of the separation membrane away from the intermediate membrane, and these functional groups exist in a state biased towards the surface side of the separation membrane.

2. The separation membrane composite according to claim 1, wherein, The average pore size of the intermediate membrane is 0.1–1.0 nm. The average pore size of the separation membrane is 0.5–10.0 nm. The average pore size of the intermediate membrane is smaller than that of the separation membrane.

3. The separation membrane composite according to claim 1 or 2, wherein, The intermediate membrane is a membrane formed from zeolite or a metal-organic structure.

4. The separation membrane composite according to claim 1 or 2, wherein, The separation membrane is a membrane formed of mesoporous materials, zeolites, or metal-organic structures.

5. The separation membrane composite according to claim 1 or 2, wherein, In the X-ray diffraction pattern obtained by irradiating the surface of the separation membrane with X-rays, peaks appear in the range of 2θ = 1 to 4°.

6. The separation membrane composite according to claim 1 or 2, wherein, The thickness of the intermediate membrane is less than 5 μm, and the thickness of the separation membrane is less than 1 μm.

7. The separation membrane composite according to claim 1 or 2, wherein, The functional group is amino.

8. A method for manufacturing a separation membrane composite, which is the method for manufacturing the separation membrane composite according to any one of claims 1 to 7, wherein, The process includes the following steps: a) Prepare a porous support; b) An intermediate film is formed on the surface of the support, and the intermediate film is a polycrystalline film with pores originating from the skeleton structure, wherein the average pore diameter is smaller than the average pore diameter of the pores near the surface of the support. c) A separation membrane is formed on the intermediate membrane, and the separation membrane is an inorganic membrane with a regular fine pore structure; as well as d) A prescribed solution is supplied to the separation membrane, thereby introducing functional groups into the pores of the surface layer of the separation membrane away from the intermediate membrane. The intermediate membrane is impermeable to the precursor solution used in step c) to form the separation membrane and the specified solution used in step d).

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