Separation membrane structure and production method for separation membrane structure

Abstract

One aspect of the present invention provides a separation membrane structure comprising a porous support and a separation membrane, wherein: the separation membrane is provided to one surface side of the porous support, and includes a first substance that is a substance having pores or a component derived from a substance having pores, and a second substance in which at least one of the chemical composition and the crystal structure is different from the first substance; and the second substance is scattered in the thickness direction of the separation membrane.

Description

Separation membrane structure and method for manufacturing the separation membrane structure

[0001] The present disclosure relates to a separation membrane structure and a method for manufacturing a separation membrane structure.

[0002] Conventionally, methods for forming a zeolite membrane on a porous support using zeolite seed crystals have been known (see Patent Documents 1 and 2). In this method, seed crystals applied to the surface of a porous support grow into a membrane by hydrothermal synthesis, thereby forming a zeolite membrane. Patent Document 3 describes the use of MFI zeolite crystals as seed crystals to form a zeolite membrane having both acid resistance and water separation properties, thereby obtaining a layer consisting of a mixed phase of MOR zeolite crystals and MFI zeolite crystals, and a layer consisting only of MOR zeolite crystals.

[0003] Japanese Patent Application Publication No. 2004-82008 Japanese Patent Application Publication No. 2008-74695 Japanese Patent No. 5734577

[0004] However, in the method described in Patent Document 3, the proportion of MFI zeolite crystals gradually decreases and the proportion of MOR zeolite crystals gradually increases from the substrate side of the zeolite membrane to the outermost surface side of the membrane. In such a structure, the MOR zeolite crystals, which are present in greater amounts on the outermost surface side than the MFI zeolite crystals, decrease the water permeation rate, which causes a problem.

[0005] According to one aspect of the present invention, there is provided a separation membrane structure comprising a porous support and a separation membrane, the separation membrane being disposed on one side of the porous support and including a first substance which is a substance having pores or a component derived from the substance having pores, and a second substance which differs from the first substance in at least one of chemical composition and crystalline structure, the second substance being scattered in the thickness direction of the separation membrane.

[0006] According to this aspect, it is possible to provide a separation membrane structure including a separation membrane having high uniformity and homogeneity in the thickness direction, and a method for manufacturing the separation membrane structure.

[0007] 4 is a cross-sectional view showing an embodiment of a separation membrane structure. FIG. 5 is a view showing a partially enlarged cross section of a separation membrane structure. FIG. 6 is a conceptual diagram showing an enlarged view of an example of powder. FIG. 7 is a schematic diagram showing an enlarged cross section of a separation membrane structure manufactured using the powder of FIG. 3. FIG. 8 is a schematic diagram showing an embodiment of a manufacturing apparatus for a separation membrane structure that manufactures a tubular separation membrane structure. FIG. 9 is a block diagram of the manufacturing apparatus for the separation membrane structure shown in FIG. 5. FIG. 10 is a perspective view showing the relationship between the sizes of a porous support and a nozzle. FIG. 11 is a side view (internal perspective view) showing an embodiment of a separation apparatus. FIG. 12 is an SEM image showing a cross section of the membrane obtained in Example 1. FIG. 13 is a schematic diagram showing a water permeation separation test apparatus. FIG. 14 is an X-ray diffraction measurement result of Example 3.

[0008] Hereinafter, embodiments of the present disclosure will be described. For each numerical range presented in this specification, the percentage of the separation membrane structure or the like that satisfies the numerical range is preferably about 85% or more, more preferably about 90% or more, and even more preferably about 95% or more, or may be 100%.

[0009] [Separation membrane structure] First, a separation membrane structure according to one embodiment will be described. Fig. 1 is a cross-sectional view showing an embodiment of the separation membrane structure. The separation membrane structure 1 shown in Fig. 1 comprises a porous support 2 and a separation membrane 3. The separation membrane 3 is provided on one surface 21 of the porous support 2. The porous support 2 supports the separation membrane 3. The porous support 2 may have any shape as long as it can supply a mixed fluid (liquid or gas) containing molecules to be separated to the separation membrane 3.

[0010] Examples of the shape of the porous support 2 include annular, square tubular, honeycomb, monolithic, flat, cylindrical, and rectangular pillar shapes. The porous support 2 is preferably tubular (annular or square tubular). In this case, the separation membrane structure 1 itself can be tubular, making it easier to configure the separation device 100 described below. In this case, the separation membrane 3 may be formed on either the outer peripheral surface side or the inner peripheral surface side of the porous support 2. However, considering the ease of forming the separation membrane 3, it is preferable to form it on the outer peripheral surface side of the porous support 2. In this case, the outer peripheral surface of the porous support 2 becomes one surface 21.

[0011] Examples of materials constituting the porous support 2 include ceramic materials, metal materials, glass materials, carbon materials, and hard resin materials. Examples of ceramic materials include alumina, mullite, zirconia, titania, yttria, silicon nitride, and silicon carbide. Examples of metal materials include aluminum or aluminum alloys, iron, stainless steel, titanium, and nickel. Examples of hard resin materials include fluorine-based resins such as polytetrafluoroethylene, polyethylene, polypropylene, polysulfone, polyphenylene sulfide, polycarbonate, polyamide, polyimide, and polyamideimide.

[0012] Among these, it is preferable that the material of the porous support 2 is at least one selected from the group consisting of alumina, mullite, stainless steel, titanium, nickel, and fluorine-based resin (particularly, polytetrafluoroethylene). By forming the porous support 2 from such a material, the mechanical strength of the porous support 2 can be improved, while also increasing the adhesion to the separation membrane 3.

[0013] The average pore diameter of the porous support 2 is preferably about 0.1 μm or more and 50 μm or less, and more preferably about 0.5 μm or more and 25 μm or less. A porous support 2 having an average pore diameter in this range can sufficiently increase the permeability of the molecules to be separated. The average pore diameter of the porous support 2 is the 50% diameter (so-called D50) in the volume cumulative pore size distribution of the porous support 2 measured using a pore distribution measuring device (e.g., a mercury porosimeter).

[0014] The average particle size of the particles 20 constituting the porous support 2 is preferably about 1 μm or more and 500 μm or less, and more preferably about 10 μm or more and 100 μm or less. In this specification, the "average particle size" can be determined, for example, as follows. The average particle size of the particles 20 can be determined by arithmetically averaging the area-equivalent circle diameters obtained in accordance with JIS Z8827-1:2018 (ISO13322-1:2014) based on an image acquired using a scanning electron microscope (SEM).

[0015] That is, for example, from the particles 20 in a cross-sectional image of the porous support 2 obtained using an SEM, 50 particles 20 whose entirety is included in the image are selected, the area-equivalent circle diameter is obtained for each selected particle 20, and the arithmetic mean of the obtained area-equivalent circle diameters can be used as the average particle size of the particles 20. Of course, other "average particle sizes" in this specification can also be obtained in a similar manner. Note that, in this specification, the porous support 2 has a microstructure in which the particles 20 are aggregated, but the microstructure of the porous support 2 is not particularly limited as long as the porous support 2 sufficiently allows the molecules to be separated to pass through and has sufficient mechanical strength.

[0016] Furthermore, the surface roughness (arithmetic mean roughness Ra) of the surface of the porous support 2 on which the separation membrane 3 is to be formed (one surface 21) is preferably about 0 μm or more and 5 μm or less, more preferably about 0 μm or more and 1 μm or less, and even more preferably about 0 μm or more and 0.6 μm or less. By reducing the surface roughness (arithmetic mean roughness Ra) of one surface 21 in this way, the surface roughness (arithmetic mean roughness Ra) of the outermost surface 321 of the separation membrane 3 formed thereon can also be reduced. Furthermore, small-angle regions, as described below, are less likely to occur in the separation membrane 3.

[0017] Furthermore, the surface roughness (maximum height roughness Rz) of the surface of the porous support 2 on which the separation membrane 3 is to be formed (one surface 21) is preferably approximately 0 μm or more and 20 μm or less, more preferably approximately 0.05 μm or more and 15 μm or less, and even more preferably 0.1 μm or more and 10 μm or less. When the surface roughness (maximum height roughness Rz) of one surface 21 is thus sufficiently small, damage such as defects that are continuous in the thickness direction is unlikely to occur on the outermost surface 321 of the separation membrane 3 formed thereon. Small angle regions, which will be described later, are also unlikely to occur. Having a certain degree of surface roughness (maximum height roughness Rz) on one surface 21 also has the advantage of improving adhesion between the porous support 2 and the separation membrane 3. In this specification, the surface roughness (arithmetic mean roughness Ra) and the surface roughness (maximum height roughness Rz) can be measured by a method conforming to JIS B0601:2013 (ISO4287:1997) using a surface profiler conforming to JIS B0651:2001 (ISO3274:1996).

[0018] A separation membrane 3 is provided on one surface 21 of the porous support 2. The separation membrane 3 is a composite membrane (composite layer) containing a first substance, which is a substance having pores or a component derived from a substance having pores, and a second substance that differs from the first substance in at least one of chemical composition and crystal structure. Examples of the first substance include inorganic substances having a crystal structure with pores, organic substances having a ring structure with pores, and metal-organic frameworks (MOFs) having a ring structure with pores. Due to their high durability and stability, inorganic substances and metal-organic frameworks are suitable as the first substance.

[0019] Specific examples of such a first substance include zeolite, a metal-organic framework, a metal oxide, a metal nitride, or a mixture thereof. These substances are preferred because they are easy to synthesize with different pore sizes. Among these, it is preferable that at least a portion of the first substance be crystalline, and more preferably, 50% or more, 80% or more, or 90% or more of the first substance be crystalline. 100% of the first substance may be crystalline. The crystalline nature of the first substance makes it easier to predict and control the chemical and physical properties of the separation membrane 3, allowing the desired separation membrane structure 1 to be obtained. Whether the powder P containing a pore-containing substance or the separation membrane 3 is crystalline and the proportion of the crystalline content can be evaluated by X-ray diffraction (XRD) measurement. Among these, it is preferable that the first substance be zeolite. Zeolite has particularly high chemical and physical stability, which significantly improves the durability of the separation membrane 3. This reduces the environmental impact and costs associated with the deterioration and replacement of the separation membrane structure 1.

[0020] Zeolites include, for example, the codes given by the International Zeolite Society: AFI, AFR, AFS, AFY, ASV, ATO, ATS, BEA, BEC, BOG, BPH, BSV, CAN, CHA, CON, CZP, DFO, EMT, EON, EZT, FAU, FER, GME, GON, -HOS, IFR, ISV, ITG, IWR, IWS, IWV, IWW, and L TF, LTL, MAZ, MEI, MFI, MOR, MOZ, MSE, MTW, MWW, NPO, OFF, OKO, OSI, POS, PUN, -RON, RWY, SAF, SAO, SBE, SBS, SBT, SEW, SFE, SFO, SFS, SOF, SOR, SOS, SOV, SSF, SSY, UOV, USI, UWY, VET, and YFI.

[0021] Furthermore, the ratio of the amount of silicon atoms to the amount of aluminum atoms contained in the crystal structure of the zeolite (hereinafter also referred to as the "silicon / aluminum ratio" or "Si / Al ratio") can be appropriately set depending on the molecular properties of the separation target, the properties of the mixed fluid containing the molecules to be separated, the usage environment of the separation membrane structure 1, etc.

[0022] In zeolites, the lower the aluminum content, i.e., the higher the Si / Al ratio, the more improved the water resistance and acid resistance. Therefore, for example, when the water concentration in the mixed fluid is high or when the mixed fluid has a low pH because it contains acetic acid or the like, it is preferable to select a zeolite with a high Si / Al ratio as the first substance. Specifically, when it is desired to improve the water resistance and acid resistance of the separation membrane structure 1 (separation membrane 3), the Si / Al ratio is, for example, preferably about 1 or more, more preferably about 10 or more, even more preferably about 50 or more, and particularly preferably about 100 or more.

[0023] On the other hand, examples of organic cyclic structures (ionophores) include structures containing at least one heteroatom such as an oxygen atom, a nitrogen atom, a sulfur atom, or a phosphorus atom (i.e., a structure in which methylene groups are bonded together via a heteroatom such as an oxygen atom, a nitrogen atom, a sulfur atom, or a phosphorus atom), or derivatives thereof, and structures composed only of methylene groups (hydrocarbon rings). Among these, preferred organic cyclic structures are structures in which methylene groups are bonded together via an oxygen atom, a nitrogen atom, a sulfur atom, or a phosphorus atom, or derivatives thereof.

[0024] Examples of such heteroatom-containing cyclic structures include structures having six or more carbon atoms and two or more types of at least one heteroatom in one ring. Specific examples of such cyclic structures include crown ether structures, propylene glycol structures, azacrown structures, thioether structures, and structures in which multiple crown rings are linked together.

[0025] Examples of the second substance contained in the separation membrane 3 include inorganic substances and hard resins. Due to their high durability and stability, inorganic substances are preferred as the second substance. Specific examples of such second substances include zeolites, metal-organic frameworks, metal oxides, metal nitrides, and mixtures thereof. These substances are preferred because they tend to improve mechanical strength and affinity with the molecules to be separated.

[0026] Among these, from the viewpoints of mechanical strength, cost, and affinity with the molecules to be separated, the second substance is preferably a metal oxide. Examples of metal oxides include titanium oxide (e.g., titanium dioxide, titanium trioxide, etc.), aluminum oxide, zinc oxide, lead oxide, lithium manganate, and strontium titanate. When the first substance contained in the separation membrane 3 is zeolite and the second substance is a metal oxide, the second substance attracts the molecules to be separated (especially water molecules), and the first substance allows the molecules to pass through. This further improves the permeation amount and selectivity of the separation membrane 3.

[0027] In order to further improve the permeation rate of the molecules to be separated, the second substance is preferably zeolite. As described above, for example, when the water concentration in the mixed fluid is high or when the mixed fluid has a low pH due to the inclusion of acetic acid or the like, it is preferable to select a zeolite with a high Si / Al ratio as the second substance.

[0028] When the first and second substances contained in the separation membrane 3 are both zeolites, the molecules to be separated can pass through both the first and second substances, improving the permeability (permeation amount) of the molecules to be separated. Furthermore, when the first and second substances are both zeolites, the first and second substances preferably have different crystal forms or Si / Al ratios (silicon / aluminum ratios). This improves the likelihood that the other substance will capture the molecules to be separated, even if the molecules to be separated cannot pass through either the first or second substance.

[0029] Combinations of the first substance and the second substance can be, for example, combinations such as those shown in the following Table 1. In Table 1, preferred combinations are indicated as C, more preferred combinations as B, even more preferred combinations as A, and particularly preferred combinations as S.

[0030]

[0031] Thus, in the separation membrane 3, the first substance having pores and the second substance that differs from the first substance in at least one of chemical composition and crystalline structure each exert their respective functions, and the permeation rate and selectivity for the molecules to be separated can be synergistically improved. Furthermore, the separation membrane 3 may be a composite membrane further containing one or more substances that differ from the first substance and the second substance in at least one of chemical composition and crystalline structure. It is preferable to appropriately determine the type and number of substances contained in the separation membrane 3 depending on the desired function of the separation membrane 3.

[0032] 1 , in the separation membrane 3, a plurality of second regions 34 made of a second material are scattered within a first region 33 made of a first material. More specifically, each second region 34 is in contact with (surrounded by) the first region 33 in both the thickness direction (vertical direction in FIG. 1 ) and the in-plane direction (horizontal direction in FIG. 1 ) of the separation membrane 3 in the cross section of the separation membrane 3. In other words, the second material is scattered in the thickness direction and the in-plane direction of the separation membrane 3.

[0033] In this way, the second substance is dispersed in multiple regions within the first substance, thereby improving the uniformity and homogeneity of the separation membrane 3. This reduces variations in the permeability and selectivity of the molecules to be separated in the in-plane direction of the separation membrane 3, thereby improving the permeation amount and separation performance of the molecules to be separated. Furthermore, the physical and chemical properties of the separation membrane 3 can be more easily predicted and controlled.

[0034] In particular, by having the second substance scattered in the thickness direction of the separation membrane 3, the properties of the separation membrane 3 (separation membrane structure 1) can be realized according to the selection of the first substance and the second substance, regardless of the thickness of the separation membrane 3. Therefore, the separation membrane 3 can be set to a desired thickness depending on the use, purpose, etc. of the separation membrane 3 (separation membrane structure 1). Furthermore, by having the second substance scattered in the in-plane direction of the separation membrane 3, it is easy to ensure the uniformity and homogeneity of the separation membrane 3 regardless of the area on which the separation membrane 3 is formed. Therefore, variation in the properties of the separation membrane 3 in the in-plane direction can be reduced. Furthermore, one surface 21 of the porous support 2 on which the separation membrane 3 is formed can be set to a desired area.

[0035] In the cross section of the separation membrane 3, the ratio S2 / S1 of the total area S2 of one or more second regions 34 made of the second material to the area S1 of the first region 33 made of the first material is preferably approximately 0.1 to 1, more preferably approximately 0.15 to 0.8, and even more preferably approximately 0.18 to 0.6. By ensuring a sufficiently large area S1 of the first region 33 made of the first material having pores, the selectivity for the molecules to be separated can be maintained and the performance of the separation membrane 3 can be improved. Furthermore, by ensuring a certain area S2 of the second region 34 made of the second material, the separation membrane 3 can function as a composite membrane with multiple functions. In the cross section of the separation membrane 3, the area S1 when the first region 33 is present in multiple locations and the area S2 of the scattered (present in multiple locations) second regions 34 each refer to the sum (total area) of the areas of the multiple first regions 33 and second regions 34, i.e., the overall area.

[0036] The average area (area per location) of the second regions 34 scattered (present at multiple locations) in the cross section of the separation membrane 3 is 0.01 μm ２ 4 μm or more ２ It is preferable that the thickness is about 0.05 μm or less. ２ 2 μm or more ２ It is more preferable that the thickness is about 0.1 μm or less. ２ 1 μm or more ２ It is even more preferable that the area of ​​the second region 34 is about 0.05 mm or less. In this way, by making the area of ​​the second region 34 sufficiently small, it is possible to further improve the uniformity and homogeneity of the separation membrane 3. Furthermore, by ensuring a certain degree of overall area of ​​the second region 34, it is possible to fully exert the effect of including the second substance in the separation membrane 3.

[0037] The average area of ​​the plurality of second regions 34 in the cross section of the separation membrane 3 is, for example, the equivalent circle diameter measured by cross-sectional microstructure observation using a SEM (scanning electron microscope). This method can be used when the brightness (or color shading) of the main components of the first region 33 and the second region 34 is different from each other. When the first region 33 and the second region 34 are difficult to distinguish using an SEM, for example, the two can be distinguished using an SEM (scanning electron microscope)-EDX (energy dispersive X-ray spectroscopy) method. The first region 33 and the second region 34 can be distinguished by superimposing, on an SEM image of the cross section of the separation membrane 3, an image (element mapping image) in which the main component (or a substance contained in a particularly large amount) of either the first region 33 or the second region 34 is colored in the separation membrane 3 in the same field of view as the SEM image. Furthermore, for example, among the locations where the main component of the second region 34 is observed, a region with a maximum length of 5.5 nm or more or an area of ​​20 nm ２ The above region may be defined as the second region 34 .

[0038] Furthermore, it is preferable that most of the second regions 34 are arranged along the in-plane direction of the separation membrane 3. In other words, it is preferable that the angle θ (minimum angle) between the long axis direction and the thickness direction of the separation membrane 3, as determined by ellipse fitting, shown in FIG. 2, is large. FIG. 2 is a partially enlarged view of the cross section of the separation membrane structure. FIG. 2 shows an enlarged view of the area surrounded by the dashed dotted line in FIG. 1. A large angle θ makes it easier to suppress variation in the properties of the separation membrane 3 in the in-plane direction. More specifically, the angle θ is preferably greater than 20° and less than or equal to 90°, more preferably approximately 30° to 90°, and even more preferably approximately 40° to 90°.

[0039] Furthermore, the proportion of the number of large-angle regions 34a, in which the angle θ is greater than 20° and less than or equal to 90°, to the total number of second regions 34 is preferably approximately 70% to 100%, more preferably approximately 80% to 100%, and even 90% to 100%, or even 100%. Furthermore, in the large-angle regions 34a, the ratio of the length in the major axis direction to the length in the minor axis direction, as determined by ellipse fitting, is preferably approximately 1.2 or greater, more preferably approximately 1.3 or greater, and even more preferably approximately 1.5 or greater. As such, the elongated shape of the large-angle regions 34a makes it easier for the second regions 34 and the first regions 33 to alternate in the thickness direction of the separation membrane 3, particularly. This allows the separation membrane 3 to exhibit the properties of both the first regions 33 and the second regions 34 in the thickness direction through which the molecules to be separated pass. The upper limit of the ratio of the length in the major axis direction to the length in the minor axis direction is not particularly limited, and may be, for example, about 10 or less, about 8 or less, about 5 or less, about 3 or less, or about 2 or less. Ellipse fitting of the second region 34 can be performed on an image obtained by observing the cross-sectional microstructure of the separation membrane 3 using, for example, SEM-EDX.

[0040] The second region 34 may also include small-angle regions 34b, in which the angle θ between the major axis direction and the thickness direction of the separation membrane, as determined by ellipse fitting, is approximately 20° or less. However, the proportion of the number of small-angle regions 34b to the total number of second regions 34 is preferably approximately 15% or less, more preferably approximately 12% or less, even more preferably approximately 10% or less, and may even be 0%. This small proportion of small-angle regions 34b that can be arranged in communication in the thickness direction of the separation membrane 3 facilitates achieving in-plane homogeneity of the separation membrane 3. Furthermore, the length of the small-angle regions 34b in the major axis direction, as determined by ellipse fitting, is preferably approximately 100 nm or less, more preferably approximately 80 nm or less, and even more preferably approximately 60 nm or less. Thus, by ensuring that the major axis length of the small-angle regions 34b is sufficiently short, it is possible to prevent or suppress the occurrence of small-angle regions 34b that penetrate the separation membrane 3 in the thickness direction. In other words, the in-plane homogeneity of the separation membrane 3 can be sufficiently improved. Furthermore, the ratio of the length in the major axis direction to the length in the minor axis direction, as determined by ellipse fitting of small-angle region 34b, is preferably about 4 or less, more preferably about 3.8 or less, and even more preferably about 3.6 or less. In this case, even if small-angle region 34b is present, its aspect ratio (ratio of the length in the major axis direction to the length in the minor axis direction) is relatively small, so that the effect on the in-plane uniformity of separation membrane 3 can be kept small.

[0041] In the separation membrane 3 as described above, the surface roughness (arithmetic mean roughness Ra) of the outermost surface 321 of the separation membrane 3 (the surface opposite to the porous support 2) shown in Figure 1 etc. is preferably about 1.3 μm or less, more preferably about 1.2 μm or less, about 1.1 μm or less, about 1 μm or less, about 0.9 μm or less, about 0.8 μm or less, or about 0.7 μm or less, and even more preferably about 0.6 μm or less, about 0.5 μm or less, about 0.4 μm or less, or about 0.3 μm or less. With this configuration, the outermost surface 321 of the separation membrane structure 1 can be formed relatively smoothly and with little waviness, so that turbulence is less likely to occur in the mixed fluid containing the molecules to be separated near the outermost surface 321, and the molecules to be separated can pass (permeate, penetrate) more uniformly in the in-plane direction of the porous support 2.

[0042] Furthermore, the surface roughness (arithmetic mean roughness Ra) of the outermost surface (opposite surface) 321 of the separation membrane 3 may be approximately 0.1 μm or more, approximately 0.11 μm or more, approximately 0.12 μm or more, approximately 0.13 μm or more, approximately 0.14 μm or more, approximately 0.15 μm or more, approximately 0.16 μm or more, approximately 0.17 μm or more, approximately 0.18 μm or more, approximately 0.19 μm or more, or approximately 0.2 μm or more. By configuring in this manner, the outermost surface 321 of the separation membrane structure 1 can have appropriate unevenness, which can increase the area of ​​contact between the separation membrane 3 (outermost surface 321) and the mixed fluid containing the molecules to be separated, and can prevent a decrease in the permeability of the molecules to be separated.

[0043] That is, the surface roughness (arithmetic mean roughness Ra) of the outermost surface 321 of the separation membrane 3 may be, for example, about 0.1 μm to 1.3 μm, about 0.11 μm to 1.2 μm, about 0.12 μm to 1.1 μm, about 0.13 μm to 1 μm, about 0.14 μm to 0.9 μm, about 0.15 μm to 0.8 μm, about 0.16 μm to 0.7 μm, about 0.17 μm to 0.6 μm, about 0.18 μm to 0.5 μm, about 0.19 μm to 0.4 μm, or about 0.2 μm to 0.3 μm. The upper and lower limit values ​​of the surface roughness (arithmetic mean roughness Ra) of the outermost surface 321 can be combined as appropriate.

[0044] The surface roughness (maximum height roughness Rz) of the outermost surface 321 of the separation membrane 3 (the surface opposite to the porous support 2) is preferably 10 μm or less, more preferably about 9 μm or less, about 8.5 μm or less, about 8 μm or less, or about 7.5 μm or less, even more preferably about 7 μm or less, about 6.5 μm or less, about 6 μm or less, or about 5.5 μm or less, and particularly preferably about 5 μm or less, about 4.5 μm or less, or about 4 μm or less. With this configuration, defects such as large irregularities and interconnected voids are unlikely to occur on the outermost surface 321 of the separation membrane structure 1. Therefore, because defects are unlikely to occur in the separation membrane 3, it is possible to prevent molecules other than the molecules to be separated from passing through the separation membrane structure 1 without passing through the separation membrane 3.

[0045] Furthermore, the surface roughness (maximum height roughness Rz) of the outermost surface (opposite surface) 321 of the separation membrane 3 may be approximately 1 μm or more, approximately 1.1 μm or more, approximately 1.2 μm or more, approximately 1.3 μm or more, approximately 1.4 μm or more, or approximately 1.5 μm or more. By configuring in this manner, appropriate unevenness is generated on the outermost surface 321 of the separation membrane structure 1, which makes it easy to ensure a sufficient area for contact between the separation membrane 3 (outermost surface 321) and the mixed fluid containing the molecules to be separated, and prevents a decrease in the permeability of the molecules to be separated.

[0046] That is, the surface roughness (maximum height roughness Rz) of the outermost surface 321 of the separation membrane 3 may be, for example, about 1 μm to 10 μm, about 1.1 μm to 9 μm, about 1.2 μm to 7 μm, about 1.3 μm to 6 μm, about 1.4 μm to 5 μm, or about 1.5 μm to 4 μm. The upper and lower limit values ​​of the surface roughness (arithmetic mean roughness Ra) of the outermost surface 321 can be combined as appropriate.

[0047] In summary, it is preferable that the surface roughness (arithmetic mean roughness Ra) of the outermost surface 321 of the separation membrane 3 (the surface opposite to the porous support 2) is approximately 1.3 μm or less, and the surface roughness (maximum height roughness Rz) of the outermost surface 321 of the separation membrane 3 (the surface opposite to the porous support 2) is approximately 10 μm or less. The outermost surface 321 that satisfies these conditions is a surface that has little waviness and does not have defects such as large irregularities. Therefore, in order to prevent turbulence from occurring in the mixed fluid containing the molecules to be separated near the outermost surface 321, it is easy for the molecules to be separated to pass uniformly in the in-plane direction of the porous support 2, and it is possible to prevent molecules other than the molecules to be separated from passing through the separation membrane structure 1. In other words, a separation membrane structure 1 having an outermost surface 321 that satisfies these conditions can improve the permeation amount of the molecules to be separated and suppress a decrease in separation performance, thereby enabling the molecules to be separated to be efficiently recovered. The proportion of outermost surface 321 of separation membrane 3 whose surface roughness falls within the above range is preferably 85% or more, more preferably 90% or more, even more preferably 95% or more, and may even be 100%.

[0048] The combination of the upper limit of the surface roughness (arithmetic mean roughness Ra) and the upper limit of the surface roughness (maximum height roughness Rz) of the outermost surface 321 of the separation membrane 3 can be, for example, the combinations shown in Table 2 below. In Table 2, a preferred combination is indicated as C, a more preferred combination as B, an even more preferred combination as A, and a particularly preferred combination as S. Furthermore, in Table 2, the smaller the upper limit of the surface roughness (arithmetic mean roughness Ra), the smoother the outermost surface 321 will be with fewer waviness and irregularities, and the smaller the upper limit of the surface roughness (maximum height roughness Rz), the fewer defects such as large irregularities and interconnected voids will be in the outermost surface 321.

[0049]

[0050] Furthermore, when the average thickness of the first portion 31 of the separation membrane 3 that penetrates into the porous support 2 is T1 [μm] and the average thickness of the second portion 32 of the separation membrane 3 excluding the first portion 31 is T2 [μm], T1 / T2 is preferably about 1 / 6 or less, more preferably about 1 / 8 or less, and even more preferably about 1 / 10 or less. With this configuration, the average thickness T1 of the first portion 31 is sufficiently small, so that it is possible to prevent or suppress high blockage of the pores on one surface 21 of the porous support 2. This makes it possible to sufficiently ensure the permeability of the molecules to be separated in the porous support 2.

[0051] Furthermore, the ratio T1 / T2 of the average thickness T1 [μm] of the first portion 31 of the separation membrane 3 to the average thickness T2 [μm] of the second portion 32 may be approximately 1 / 1000 or more, approximately 1 / 500 or more, or approximately 1 / 250 or more. By ensuring a certain level of average thickness T1 in this way, it is possible to improve the adhesion between the porous support 2 and the separation membrane 3. That is, the ratio T1 / T2 of the average thickness T1 [μm] of the first portion 31 of the separation membrane 3 to the average thickness T2 [μm] of the second portion 32 may be approximately 1 / 1000 or more and 1 / 6 or less, approximately 1 / 500 or more and 1 / 8 or less, or approximately 1 / 250 or more and 1 / 10 or less.

[0052] The "average thickness" of each portion is the arithmetic mean value of thicknesses measured at at least three locations by cross-sectional microstructural observation using a SEM (scanning electron microscope). The at least three locations are selected to be at least 20 μm apart in the in-plane direction of the separation membrane 3. Furthermore, when measuring at each location, it is preferable to measure the thickness of the first portion 31 and the thickness of the second portion 32 so that they are positioned on the same straight line in the thickness direction of the separation membrane 3 (separation membrane structure 1).

[0053] When the interface between the porous support 2 and the separation membrane 3, which is the boundary between the first portion 31 and the second portion 32, is unclear, the interface can be identified, for example, using a scanning electron microscope (SEM)-energy dispersive X-ray spectroscopy (EDX). That is, in observing the cross-sectional microstructure of the separation membrane structure 1, a measurement area is used in which the in-plane direction of the separation membrane structure 1 is the long side and the thickness direction of the separation membrane structure 1 is the short side, and the long side is set to be at least 10 times the length of the short side. At each location where the thickness of the first portion 31 and the thickness of the second portion 32 are measured, the measurement area is moved from the outermost surface 321 of the separation membrane 3 toward the porous support 2 along the thickness direction of the separation membrane 3. At this time, the measurement areas before and after each movement are made not to overlap with each other. Elemental analysis is performed on each measurement area. Then, for example, a graph of each component detected by elemental analysis is created, and the thickness of the first portion 31 and the thickness of the second portion 32 are measured at the interface between the porous support 2 and the separation membrane 3, where the composition of the most frequently detected component changes or the inflection point where the concentration ratio of an element specific to the separation membrane 3 changes significantly. Here, the dashed dotted line in Figure 1 indicates the average thickness of the first portion 31 and the second portion 32. The first portion 31 can also be called a composite portion where the constituent material of the separation membrane 3 and the constituent material of the porous support 2 are composited.

[0054] It has been difficult to form a separation membrane 3 that satisfies this relationship in the past. In conventional hydrothermal synthesis methods, seed crystals applied to the surface of a porous support diffuse into the interior of the porous support, which tends to increase the effective thickness of the formed zeolite membrane, and depending on the viscosity and flow rate of the mixed fluid containing the molecules to be separated, the permeability of the molecules to be separated may decrease. In particular, when attempting to grow a zeolite membrane to a sufficient thickness, depending on the treatment conditions (temperature, time, etc.), the zeolite membrane tends to grow not only on the porous support but also toward the interior of the porous support.

[0055] For example, in Japanese Patent No. 6,882,561, an effort has been made to optimize the pore distribution on the outermost surface of the porous support and the particle size distribution of the seed crystals to suppress the diffusion of the seed crystals into the porous support. However, even with this method, it is difficult to suppress the diffusion of the seed crystals into the porous support, and if the pore distribution on the outermost surface of the porous support is made too small, the permeability of the molecules to be separated in the porous support itself tends to decrease. On the other hand, with the separation membrane structure 1 according to the above embodiment, there is no need to apply seed crystals to the surface of the porous support 2 in the first place, so the above-mentioned problems are less likely to occur. Therefore, the value of T1 / T2 can be kept small.

[0056] The average thickness T1 is preferably about 1 μm or less, more preferably about 0.8 μm or less, and even more preferably about 0.3 μm or less. This makes it possible to suitably suppress a decrease in the permeability of the molecules to be separated in the porous support 2 in the area where the first portion 31 is present. The average thickness T1 may be 0 μm. On the other hand, the average thickness T2 is preferably about 0.5 μm or more and 10 μm or less, more preferably about 0.8 μm or more and 9 μm or less, and even more preferably about 1.2 μm or more and 8 μm or less. This makes it possible to prevent a decrease in the permeability of the molecules to be separated in the second portion 32 while sufficiently maintaining the selectivity and mechanical strength of the molecules to be separated.

[0057] The separation membrane 3 can be formed using powder P having a configuration as shown in Fig. 3. As described in detail below, the separation membrane 3 can be formed by spraying the powder P onto one surface 21 of the porous support 2. As a method for spraying the powder P onto one surface 21 of the porous support 2, it is preferable to adopt, for example, an aerosol deposition method.

[0058] FIG. 3 is a conceptual diagram showing an enlarged view of an example of a powder. FIG. 4 is a schematic diagram showing an enlarged view of a cross section of a separation membrane structure produced using the powder of FIG. 3. As shown in FIG. 3, the powder P is an aggregate of first particles 3a containing a first substance and having pores, and second particles 3b containing a second substance. As shown in FIG. 4, by spraying the powder P of FIG. 3 onto one surface 21 of a porous support 2, a separation membrane 3 containing a component 3a' derived from the first particles and a component 3b' derived from the second particles can be formed. The component 3a' derived from the first particles and the component 3b' derived from the second particles each contain at least one of the first particles 3a or the second particles 3b themselves, a component formed by deformation of the first particles 3a or the second particles 3b, and small pieces detached from the first particles 3a or the second particles 3b. The first particle-derived component 3a' and the second particle-derived component 3b' preferably include at least one of a component formed by deformation (change in shape) of the first particle 3a or the second particle 3b, and small pieces detached from the first particle 3a or the second particle 3b. The first particle 3a and the second particle 3b are sprayed onto one surface 21, and the first particle 3a and the second particle 3b collide with the one surface 21 with such high collision energy that the first particle 3a and the second particle 3b are deformed or partially detached, thereby forming the separation membrane 3. This increases the adhesion between the separation membrane 3 and the porous support 2, thereby improving the mechanical strength of the separation membrane structure 1. Note that the second particle 3b is sprayed and deformed, and partially detached while depositing on one surface 21 of the porous support 2, thereby minimizing the proportion of the small-angle region 34b (see FIG. 2 ), as described above. Furthermore, when the surface roughness (arithmetic mean roughness Ra) and surface roughness (maximum height roughness Rz) of one surface 21 of the porous support 2 are small values ​​as described above, the components 3b' derived from the second particles deposited thereon tend to form large-angle regions 34a (see Figure 2) along the thickness direction of the separation membrane 3.

[0059] The average particle size of the first particles 3a is preferably about 0.01 μm or more and 100 μm or less, more preferably about 0.05 μm or more and 50 μm or less, and even more preferably about 0.1 μm or more and 10 μm or less. As such, when the average particle size of the first particles 3a is sufficiently small, the separation membrane 3 can be formed uniformly, homogeneously, and densely, as shown in FIG. 4 . Furthermore, when the average particle size of the first particles 3a is relatively large, the powder P can have sufficient collision energy when sprayed onto one surface 21 of the porous support 2, making it easier to form the separation membrane 3. Furthermore, the first particles 3a of the powder P can adhere with sufficient strength to the one surface 21, the other first particles 3a (components 3a' derived from the first particles), and the second particles 3b (components 3b' derived from the second particles), making it less likely that damage such as cracks or interconnected voids (through-holes) will occur in the separation membrane 3, thereby improving the quality of the separation membrane structure 1.

[0060] The average particle size of the second particles 3b is preferably about 0.01 μm or more and 100 μm or less, more preferably about 0.05 μm or more and 50 μm or less, and even more preferably about 0.1 μm or more and 10 μm or less. By setting the average particle size of the second particles 3b in this manner, the quality of the separation membrane structure 1 can be improved, as in the case of the first particles 3a.

[0061] It is more preferable that the average particle size of the second particles 3b is larger than the average particle size of the first particles 3a. In this case, since the average particle size of the first particles 3a is small, even if the collision energy of the first particles 3a is small when the powder P is sprayed onto one surface 21 of the porous support 2 and the powder P collides with the one surface 21 to form the separation membrane 3, the second particles 3b can impart collision energy to the entire powder P. Therefore, the separation membrane 3 can be reliably formed, and the separation membrane 3 can be adhered to the one surface 21 with sufficient strength.

[0062] By mixing the first particles 3 a and the second particles 3 b under the following conditions, it is possible to achieve a good balance between imparting collision energy and improving the quality of the separation membrane 3. By including a sufficient amount of the second particles 3 b in the powder P, it is possible to impart appropriate collision energy to the powder P, thereby facilitating the formation of the separation membrane 3.

[0063] That is, the loose bulk density of the powder P as a whole is 0.3 g / cm ３ It is preferable that the density is about 0.4 g / cm or more. ３ It is more preferable that the loose bulk density is about 100 mL or more. The loose bulk density can be measured according to JIS K7365:1999 (ISO60:1977) or a method conforming thereto. That is, powder P is gently poured into a 100 mL container using a funnel without applying any physical external force (tapping, pushing, etc.), and the weight of powder P when the container is leveled is divided by the volume (100 mL) to obtain the loose bulk density.

[0064] When the powder P has such a loose bulk density, the powder P contains many particles with a relatively large average particle size (e.g., second particles 3b). This allows the collision energy when the powder P is sprayed to be sufficiently large. Furthermore, to prevent the proportion of particles with a relatively large average particle size from becoming too high, the powder P contains an appropriate amount of particles with a small average particle size (e.g., first particles 3a). This allows the formed separation membrane 3 to have sufficient density and homogeneity, improving the quality of the separation membrane 3.

[0065] Furthermore, when the cumulative 10% diameter in the volume-based particle size distribution of powder P is defined as D10 and the cumulative 90% diameter is defined as D90, it is preferable that D10 is approximately 0.05 μm or more and 1.0 μm or less, and D90 is approximately 0.8 μm or more and 5 μm or less, and it is more preferable that D10 is approximately 0.1 μm or more and 0.8 μm or less, and D90 is approximately 1 μm or more and 4 μm or less. These values ​​are examples of particularly preferred ranges and can be combined with each other. Note that this particle size distribution can be measured, for example, using a particle size distribution measuring device using a laser diffraction / scattering method. Then, based on the obtained particle size distribution, the particle size at the 10% cumulative diameter from the smallest particle size side can be calculated as D10, and the particle size at the 90% cumulative diameter from the smallest particle size side can be calculated as D90.

[0066] That is, the powder P containing first particles 3a and second particles 3b larger in diameter than the first particles 3a preferably has two maxima in its volumetric particle size frequency distribution. The powder P may also contain particles with different average particle sizes in addition to the first particles 3a and the second particles 3b. In this case, the particle size distribution of the powder P may have three or more maxima. Thus, when the difference in average particle size between the first particles 3a and the second particles 3b is sufficiently large, the first particles 3a have a sufficiently small average particle size, which allows the separation membrane 3 to be formed uniformly, homogeneously, and densely, while the second particles 3b have a sufficiently large average particle size, which makes it easy to impart sufficient and appropriate collision energy to the entire powder P. In other words, the powder P preferably contains two or more types of particles exhibiting different particle size distributions. The maxima of these different particle size distributions correspond to two or more maxima of the powder P.

[0067] Furthermore, when the separation membrane 3 further contains one or more substances, the powder P further contains one or more types of particles. It is preferable to appropriately select the particles that constitute the powder P in accordance with the desired properties of the separation membrane 3.

[0068] [Method for manufacturing a separation membrane structure] Next, a method for manufacturing a separation membrane structure will be described. The method for manufacturing a separation membrane structure includes a step (first step) of preparing a powder P containing first particles 3a (first substance) and second particles 3b (second substance) having pores, and a porous support 2, and a step (second step) of spraying the powder P onto one surface 21 of the porous support 2 to form a separation membrane 3, thereby obtaining a separation membrane structure 1.

[0069] (First Step) First, a powder P containing first particles 3a and second particles 3b and a porous support 2 are prepared. Both the powder P and the porous support 2 may be commercially available or may be prepared by hand. In the latter case, the powder P can be prepared by, for example, hydrothermal synthesis of the first particles 3a and the second particles 3b. By changing the raw materials and conditions used in the hydrothermal synthesis, the pore size and type of crystal structure of the first particles 3a can be changed. A structure-directing agent may be used to adjust the pore size. The prepared first particles 3a and second particles 3b are then mixed wet or dry to prepare the powder P.

[0070] On the other hand, the porous support 2 can be produced, for example, as follows. First, a molded body containing the particles 20, an organic binder, and, if necessary, a pH adjuster and a surfactant is formed. For molding the molded body, for example, injection molding, extrusion molding, press molding, etc. can be used. Next, the molded body is fired to obtain the porous support 2. The firing conditions can be, for example, about 900°C or higher and 1450°C or lower, and about 1 hour or higher and 100 hours or lower. Note that the organic binder may be removed by this firing, or a degreasing step for removing the organic binder may be provided prior to firing.

[0071] (Second Step) Next, a membrane is formed by spraying the powder P onto one surface 21 of the porous support 2. Examples of spraying methods include aerosol deposition, spray coating, and electrodeposition coating. Among these, in the second step (the step of obtaining the separation membrane structure 1), it is preferable to spray the powder P onto one surface 21 of the porous support 2 by aerosol deposition. By employing the aerosol deposition method, membrane formation can be performed at room temperature, thereby reducing power consumption.

[0072] The first particles 3a and second particles 3b in the powder P sprayed toward the surface 21 of the porous support 2 collide with and deposit on one surface 21 of the porous support 2, thereby forming a separation membrane 3 on the one surface 21. At this time, at least a portion of the first particles 3a and second particles 3b may deform during the process of forming the separation membrane 3, or a portion of them may detach and adhere. In particular, the second particles 3b may be deformed or partially detached while depositing on the one surface 21, thereby increasing the proportion of the large-angle regions 34a shown in FIG. 2 in the second region 34 composed of the component 3b' derived from the second particles, and reducing the proportion of the small-angle regions 34b. In particular, when the surface roughness (arithmetic mean roughness Ra) and surface roughness (maximum height roughness Rz) of the one surface 21 of the porous support 2 are sufficiently small, the component 3b' derived from the second particles deposited thereon is likely to form the large-angle regions 34a. Furthermore, it is preferable that at least a portion of the second particles 3b fall, float, or adhere to the inner surface of the chamber within the chamber, so that the mass ratio of the component 3b' derived from the second particles in the separation membrane 3 becomes significantly smaller than the mass ratio of the second particles 3b to the powder P. This allows the powder P to contain a large amount of the second particles 3b, thereby imparting sufficient collision energy, and also makes it possible to appropriately reduce the area of ​​the region in the separation membrane 3 where the component 3b' derived from the second particles is formed, thereby satisfying the above-mentioned S2 / S1. In this manner, the separation membrane structure 1 can be obtained.

[0073] [Separation Membrane Structure Manufacturing Apparatus] Hereinafter, a separation membrane structure manufacturing apparatus 4 that manufactures a separation membrane structure 1 by forming a separation membrane 3 using an aerosol deposition method will be described. In this specification, a case in which the separation membrane 3 is formed over the entire outer peripheral surface (one surface 21) of a tubular porous support 2 will be described as an example.

[0074] Incidentally, a program for realizing the software appearing in one embodiment may be provided as a non-transitory computer-readable recording medium, or may be provided so as to be downloadable from an external server, or may be provided so that the program is started on an external computer and its functions are realized on a client terminal (so-called cloud computing).

[0075] Furthermore, various information processing according to an embodiment may realize input and output corresponding to the input. Here, the form of information referenced in such information processing (hereinafter referred to as reference information) is not limited as long as an output is obtained as a result of the input. The reference information may be, for example, rule-based information such as a database, a lookup table, or a predetermined function (including a determination formula such as a regression formula constructed using a statistical method), a trained model that has previously learned the correlation between input and output, or a generative AI such as a large-scale language model or a visual language model that can output a desired result by inputting a prompt.

[0076] In one embodiment, the term "unit" may include, for example, a combination of hardware resources implemented by a circuit in the broad sense and software information processing that can be specifically realized by these hardware resources. In one embodiment, various information is handled, and this information is represented, for example, by physical values ​​of signal values ​​representing voltage or current, high or low signal values ​​as a binary bit set consisting of 0 or 1, or quantum superposition (so-called quantum bits), and communication and calculations can be performed on the circuit in the broad sense.

[0077] Furthermore, a circuit in a broad sense is a circuit realized by at least an appropriate combination of a circuit, circuitry, a processor, a memory, etc. The processor may be a general-purpose processor or a dedicated circuit. That is, it includes application specific integrated circuits (ASICs), programmable logic devices (e.g., simple programmable logic devices (SPLDs), complex programmable logic devices (CPLDs), and field programmable gate arrays (FPGAs)), etc.

[0078] FIG. 5 is a schematic diagram showing an embodiment of a separation membrane structure manufacturing apparatus for manufacturing a tubular separation membrane structure. FIG. 6 is a block diagram of the separation membrane structure manufacturing apparatus shown in FIG. 5. FIG. 7 is a perspective view showing the relationship between the size of the porous support and the nozzle. The separation membrane structure manufacturing apparatus 4 shown in FIG. 5 includes a chamber 5, a support mechanism 6 that supports a tubular porous support 2 within the chamber 5, and a spray mechanism 7 that sprays powder P containing first particles (first substance) 3a and second particles (second substance) 3b having pores toward the porous support 2. The average particle size of the particles (first particles 3a and second particles 3b) contained in the powder P is preferably approximately 0.1 μm or more and 50 μm or less, and more preferably approximately 0.5 μm or more and 35 μm or less. This allows the powder P to be sprayed at a higher speed from the spray outlet 711 of the nozzle 71.

[0079] The support mechanism 6 has a support rod 61 inserted inside the tubular porous support 2 and a motor 62 that rotates the support rod 61. The motor 62 is rotated while the porous support 2 is supported by the support rod 61. The support mechanism 6 is configured to rotate the tubular porous support 2 about its central axis. This configuration makes it easy to form a uniform and homogeneous separation membrane 3 on the outer peripheral surface (one surface 21) of the porous support 2 along the circumferential direction of the porous support 2. The rotation speed of the porous support 2 is preferably approximately 1 rpm or more and 60 rpm or less, and more preferably approximately 5 rpm or more and 30 rpm or less. Rotating the porous support 2 at such a rotation speed makes it easy to improve the uniformity and homogeneity of the separation membrane 3 along the circumferential direction of the porous support 2.

[0080] The ejection mechanism 7 has a nozzle 71 for ejecting the powder P, and is configured to move the nozzle 71 along the central axis (longitudinal direction) of the porous support 2 using a moving mechanism 78 (see FIG. 8 ). This configuration facilitates the formation of a uniform and homogeneous separation membrane 3 along the longitudinal direction of the porous support 2 on the outer peripheral surface (one surface 21) of the porous support 2. The moving speed of the nozzle 71 is preferably approximately 0.1 cm / sec or more and 30 cm / sec or less, and more preferably approximately 0.5 cm / sec or more and 20 cm / sec or less. Moving the nozzle 71 at this moving speed facilitates the enhancement of the uniformity and homogeneity of the separation membrane 3 along the longitudinal direction of the porous support 2. In the ejection mechanism 7, the nozzle 71 is connected to a gas cylinder 72 via a transfer pipe 73. A mass flow controller 74 and an aerosol generator 75 are provided in the transfer pipe 73, in this order from the gas cylinder 72 side.

[0081] In the separation membrane structure manufacturing apparatus 4, a carrier gas is supplied from a gas cylinder 72 to a carrier pipe 73, and the flow rate of the carrier gas is adjusted by a mass flow controller 74. An aerosol generator 75 is loaded with powder P to be sprayed, and the powder P is dispersed in the carrier gas flowing through the carrier pipe 73 to transport the powder P to the nozzle 71. That is, the jetting mechanism 7 is equipped with the aerosol generator 75 that mixes the powder P with the carrier gas to generate an aerosol. The powder P is then jetted from the nozzle 71 onto the outer peripheral surface of the porous support 2 at a jetting speed of approximately equal to or greater than subsonic speed and equal to or less than supersonic speed. In addition, a pump 81 is connected to the chamber 5 as a pressure reducing mechanism 8, and the pressure within the chamber 5 can be adjusted.

[0082] The separation membrane structure manufacturing apparatus 4 further includes a control means 9. The control means 9 is configured to control the operation of the separation membrane structure manufacturing apparatus 4. As shown in Fig. 6, the motor 62, the moving mechanism 78, and the pump 81 are each electrically connected to the control means 9. Although not shown, the control means 9 is also electrically connected to an operation unit, a display unit, a power supply unit, and the like. The control means 9 incorporates calculation units 91 and 92.

[0083] The calculation unit 91 is composed of, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), etc. The calculation unit 91 realizes various functions related to the separation membrane structure manufacturing apparatus 4 by reading out predetermined programs stored in the storage unit 92. In other words, information processing by the software stored in the storage unit 92 is specifically realized by the calculation unit 91. The calculation unit 91 is not limited to being a single unit, and multiple calculation units 91 may be provided for each function. A combination of these may also be used. In particular, it is preferable to provide a calculation unit 91 for controlling the operation of the motor 62, separate from the calculation unit 91 related to the movement of the nozzle 71 by the movement mechanism 78.

[0084] The memory unit 92 stores various pieces of information defined above. This can be implemented, for example, as a storage device such as a solid state drive (SSD) that stores various programs and the like related to the separation membrane structure manufacturing apparatus 4 executed by the calculation unit 91, or as a memory such as a random access memory (RAM) that stores temporarily required information (arguments, arrays, etc.) related to the program calculations. The memory unit 92 also stores various programs, variables, etc. related to the separation membrane structure manufacturing apparatus 4 executed by the calculation unit 91.

[0085] A method for manufacturing a separation membrane structure using such a manufacturing apparatus 4 for a separation membrane structure will now be described. First, the porous support 2 is attached to the support rods 61 of the support mechanism 6. Then, the chamber 5 is depressurized. The pressure within the chamber 5 (depressurized pressure) is not particularly limited, but is preferably about 5 Pa or more and 1000 Pa or less. By depressurizing to this level, convection within the chamber 5 is suppressed, making it easier to spray powder onto one surface 21 of the porous support 2. In this state, the motor 62 is operated to start rotation of the porous support 2 about its central axis.

[0086] Next, a carrier gas is supplied from a gas cylinder 72 to a carrier pipe 73, and while the flow rate of the carrier gas is adjusted by a mass flow controller 74, the carrier gas is supplied to an aerosol generator 75 filled with powder P. This causes the powder P to be dispersed and accelerated in the carrier gas, generating an aerosol. The aerosol (powder P) is then sprayed from a nozzle 71 toward one surface 21 of the porous support 2. At this time, an inert gas may be supplied to the aerosol, and the aerosol may be further accelerated by the supply pressure of at least one of the carrier gas and the inert gas.

[0087] The carrier gas may be, for example, oxygen (O ２ ), nitrogen (N ２Gases such as argon (Ar), helium (He), or air can be used. The flow rate and flow rate of the carrier gas can be set appropriately depending on the amount of aerosol supplied, the constituent material, average particle size, flow rate, and flow rate of the powder P sprayed from the nozzle 71. The flow rate and flow rate of the carrier gas can also be set in conjunction with the flow rate and flow rate of the inert gas. The aerosol is sprayed from the nozzle 711 of the nozzle 71 at a speed greater than or equal to subsonic and less than or equal to supersonic to deposit the powder on one surface 21 of the porous support 2. At this time, the spray rate of the aerosol (powder P) onto one surface 21 of the porous support 2 is preferably set to approximately 10 m / s or more and 1000 m / s or less, and more preferably set to approximately 10 m / s or more and 250 m / s or less. At this time, the nozzle 71 can be moved along the central axis of the porous support 2 as needed.

[0088] Here, as shown in Figure 7, when the nozzle 71 has a rectangular outlet 711 for spraying powder P, when the outer diameter of the porous support 2 is R [mm] and the length of the outlet 711 along the radial direction of the porous support 2 is W [mm], it is preferable that W / R is approximately 0.1 or more and 1 or less, more preferably 0.2 or more and 0.8 or less, and even more preferably 0.3 or more and 0.6 or less.

[0089] By designing in this way, W / R is sufficiently small, and it is possible to prevent the formation of unintended gaps when the powder P is deposited on one surface 21 of the porous support body 2. In other words, it is possible to prevent the formation of defects such as cracks or interconnected voids, excessively large irregularities, etc. in the separation membrane 3, thereby improving the quality of the separation membrane 3.

[0090] Furthermore, since W / R is sufficiently large, it is possible to prevent the powder P from depositing more densely than necessary when it is deposited on one surface 21 of the porous support 2. This improves the productivity of the separation membrane 3. That is, by setting W / R within the above range, it is possible to form a high-quality separation membrane with high productivity.

[0091] The specific value of the width W is not particularly limited, but is preferably about 1 mm to 50 mm, more preferably about 5 mm to 40 mm, and even more preferably about 10 mm to 30 mm. In this case, a sufficient amount of powder P can be ejected onto the porous support 2, and the above-mentioned effect can be further improved.

[0092] When the first particles 3 a and second particles 3 b contained in the powder P collide with the porous support 2, at least some of them are crushed (pulverized) and / or deformed, and are deposited on one surface 21 of the porous support 2. At this time, it is preferable that at least some of the second particles 3 b do not deposit but fall, float, or adhere to the inner surface of the chamber 5 within the chamber 5. Through the above steps, a separation membrane 3 having a predetermined thickness is obtained.

[0093] In addition to the nozzle 71 that sprays the powder P, a nozzle that sprays gas may be provided near the position on one surface 21 of the porous support body 2 where the powder P is sprayed. This makes it possible to remove excess powder P on one surface 21 of the porous support body 2 (powder P that could not be bonded to one surface 21). The removed powder P may be collected and reused as material for the powder P.

[0094] Furthermore, regardless of whether or not a nozzle for spraying gas is used, the powder P that has fallen, adhered, or floated in the chamber 5 without being able to form the separation membrane 3 may be collected and reused as material for the powder P. That is, the method for manufacturing a separation membrane structure may further include a recycling step, after the second step, of reusing at least a portion of the powder P that was not used to form the separation membrane 3. In this case, it is possible to reduce the amount of powder P produced when manufacturing the separation membrane 3 and the amount of powder P that was not used to form the separation membrane 3 that is discarded. Therefore, it is possible to reduce the environmental impact and manufacturing costs incurred when manufacturing the separation membrane structure 1.

[0095] According to the manufacturing method described above (particularly the aerosol deposition method), a composite membrane with high uniformity and homogeneity in both the thickness direction and the in-plane direction can be formed as the separation membrane 3 on one surface 21 of the porous support 2. In addition, it is possible to prevent defects such as large irregularities and interconnected voids from occurring on the outermost surface 321 of this separation membrane 3. Furthermore, it is possible to selectively form the separation membrane 3 on one surface 21 of the porous support 2 while preventing or suppressing the separation membrane 3 from being formed inside the porous support 2. A separation membrane 3 with such a configuration is difficult to form by conventional hydrothermal synthesis methods.

[0096] The separation membrane structure manufacturing apparatus 4 is not limited to the above-described configuration, and various omissions, substitutions, and modifications can be made. For example, the porous support 2 may be flat, in which case a stage or arm or the like that holds the flat porous support is disposed above the nozzle of the separation membrane structure manufacturing apparatus 4. Furthermore, although the case where the separation membrane structure 1 is manufactured by moving the nozzle 71 of the separation membrane structure manufacturing apparatus 4 without moving the porous support 2 has been described, the separation membrane structure 1 may also be manufactured by fixing the nozzle 71 of the separation membrane structure manufacturing apparatus 4 and moving the porous support 2 in an in-plane direction facing the nozzle 711 of the nozzle 71.

[0097] Next, a separation device 100 including a tubular separation membrane structure 1 will be described. FIG. 8 is a side view (internal perspective view) showing an embodiment of the separation device. The separation device 100 shown in FIG. 8 includes a plurality of separation membrane structures 1 and a housing 200 that houses the plurality of separation membrane structures 1 in an internal space 201. Each separation membrane structure 1 is tubular. In other words, the separation device 100 is a multi-tube type device. Such a multi-tube type separation device 100 can ensure sufficient opportunity for contact between the separation membrane structure 1 and a mixed fluid (liquid or gas) containing molecules to be separated. As a result, the molecules to be separated can be separated smoothly and reliably.

[0098] The mixed fluid may be passed through the inside of each separation membrane structure 1, or may be passed through the outside of each separation membrane structure 1 (i.e., the internal space 201 of the housing 200). For example, when the mixed fluid is passed through the inside of each separation membrane structure 1, the separated molecules move into the internal space 201 of the housing 200. In order to efficiently recover these separated molecules, the internal space 201 may be depressurized or a sweep gas may be supplied.

[0099] As described above, the present invention can provide a separation membrane structure 1, a method for producing the separation membrane structure 1, and a separation device 100 that have excellent permeability to molecules to be separated by highly suppressing the formation of the separation membrane 3 inside the porous support 2. Furthermore, the present invention may be provided in the following aspects.

[0100] (1) A separation membrane structure comprising a porous support and a separation membrane, the separation membrane being provided on one side of the porous support and including a first substance that is a substance having pores or a component derived from the substance having pores, and a second substance that differs from the first substance in at least one of chemical composition and crystal structure, the second substance being scattered in the thickness direction of the separation membrane.

[0101] (2) The separation membrane structure according to (1) above, wherein the second substance is further scattered in the in-plane direction of the separation membrane.

[0102] (3) In the separation membrane structure described in (1) or (2) above, in the cross section of the separation membrane, the ratio of the total area of ​​one or more second regions made of the second material to the area of ​​the first region made of the first material is 0.1 or more and 1 or less.

[0103] (4) In the separation membrane structure described in (3) above, the proportion of the number of small-angle regions, in which the angle between the major axis direction and the thickness direction of the separation membrane as determined by ellipse fitting is 20° or less, to the total number of the one or more second regions is 15% or less.

[0104] (5) The separation membrane structure according to (4) above, wherein the length of the small-angle region in the major axis direction is 100 nm or less.

[0105] (6) The separation membrane structure according to (5) above, wherein the ratio of the length in the major axis direction to the length in the minor axis direction by ellipse fitting of the small angle region is 4 or less.

[0106] (7) The separation membrane structure according to any one of (1) to (6) above, wherein the surface roughness (arithmetic mean roughness Ra) of the surface of the separation membrane opposite to the porous support is 1.3 μm or less.

[0107] (8) The separation membrane structure according to any one of (1) to (7), wherein the surface roughness (maximum height roughness Rz) of the surface of the separation membrane opposite to the porous support is 10 μm or less.

[0108] (9) In the separation membrane structure described in any one of (1) to (8) above, when the average thickness of the first portion of the separation membrane embedded in the porous support is T1 [μm] and the average thickness of the second portion of the separation membrane excluding the first portion is T2 [μm], T1 / T2 is 1 / 6 or less.

[0109] (10) The separation membrane structure according to (9) above, wherein the average thickness T1 is 1 μm or less.

[0110] (11) The separation membrane structure according to (9) or (10) above, wherein the average thickness T2 is 0.5 μm or more and 10 μm or less.

[0111] (12) In the separation membrane structure according to any one of (1) to (11) above, the first substance is a zeolite, a metal-organic framework, a metal oxide, a metal nitride, or a mixture thereof.

[0112] (13) In the separation membrane structure according to any one of (1) to (12) above, the second substance is a zeolite, a metal-organic framework, a metal oxide, a metal nitride, or a mixture thereof.

[0113] (14) The separation membrane structure according to any one of (1) to (13) above, wherein the first substance is a zeolite and the second substance is a metal oxide.

[0114] (15) In the separation membrane structure described in any one of (1) to (14) above, the first substance and the second substance are both zeolite, and the first substance and the second substance have different crystal structures.

[0115] (16) In the separation membrane structure described in any one of (1) to (15) above, the first substance and the second substance are both zeolite, and the first substance and the second substance have different silicon / aluminum ratios.

[0116] (17) A method for producing a separation membrane structure according to any one of (1) to (16) above, comprising the steps of preparing a powder containing the first substance and the second substance and the porous support, and spraying the powder onto one surface of the porous support to form the separation membrane on the one surface, thereby obtaining the separation membrane structure.

[0117] (18) In the method for producing a separation membrane structure according to (17) above, in the step of obtaining the separation membrane structure, the powder is sprayed onto the one surface of the porous support by an aerosol deposition method.

[0118] As described above, various embodiments of the present disclosure have been described, but these are presented as examples and do not limit the scope of the invention in any way. The novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Such embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as set forth in the claims.

[0119] For example, one or more layers having any desired function may be further provided between the porous support 2 and the separation membrane 3. Such functions preferably include, for example, a function to increase the adhesion between the porous support 2 and the separation membrane 3, a function to prevent a sudden change in the average pore size at the boundary between the porous support 2 and the separation membrane 3, a function to relieve stress between the porous support 2 and the separation membrane 3, and a function to increase the selectivity of the molecules to be separated.

[0120] [Examples] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0121] 1. Preparation of Membrane Structure (Example 1) Preparation of Porous Support A porous alumina tube was cut to a length of 50 mm, washed with ion-exchanged water and ethanol in that order, and then dried before use. The porous alumina tube had an outer diameter of 12 mm, an inner diameter of 9 mm, and an average pore diameter of 1.2 μm.

[0122] Preparation of powder P for aerosol deposition method 2 g of zeolite (LTA type) with an average particle size of 50 nm as the first particles and 2 g of titanium oxide (TiO ２ 98 g of rutile-type cellulose syrup and 60 g of ethanol (99.5% by mass) were placed in a container and kneaded using a planetary centrifugal mixer. Kneading was performed for 2 minutes at a revolution speed of 2,000 rpm and a rotation speed of 800 rpm. The slurry obtained after kneading was left at 70°C for 3 hours and then left at 100°C for 1 hour to dry. The dried product obtained by drying was pulverized using a blade mill at 20,000 rpm for 1 minute. This resulted in a powder. In other words, the mixing ratio of the first particles in the powder was 2%.

[0123] Formation of a membrane on one surface of a porous support The membrane was formed using a membrane structure manufacturing apparatus 4 shown in Figure 5. First, the porous support was set on a support rod 61 of a support mechanism 6 that supports the porous support rotatably around its central axis. Next, the powder was sprayed onto the outer peripheral surface (one surface) of the porous support at approximately 20°C.

[0124] Specifically, the powder P to be sprayed was loaded into the aerosol generator 75, and the chamber 5 containing the porous support was depressurized to 5 Pa by the pump 81. In this state, the powder P was sprayed onto the rotating porous support from a nozzle 71 having a rectangular nozzle 711 measuring 10 mm x 0.5 mm in plan view. While the powder was being sprayed, the pressure inside the chamber 5 was adjusted to be approximately 150 Pa or more and 200 Pa or less. The width W of the nozzle 711, which is the length along the radial direction of the porous support, was 10 mm. In other words, the W / R ratio was 0.83. At this time, nitrogen gas (N ２ ) was used, and this nitrogen gas was supplied from a gas cylinder 72 to an aerosol generator 75 filled with powder, thereby dispersing the powder P in the nitrogen gas to generate an aerosol. The flow rate of the nitrogen gas was adjusted by a mass flow controller 74 installed upstream of the aerosol generator 75. The mass flow controller 74 also adjusted the amount of nitrogen gas supplied so that the pressure inside the aerosol generator 75 was 50 Pa. The aerosol was then ejected from a nozzle 71 toward the porous support to form a film. The ejection speed of the aerosol from the nozzle 71 was 250 mm / sec, and the distance from the nozzle 71 to one surface of the porous support was 10 mm. The rotation speed around the central axis of the porous support was 5 rpm, and the movement speed of the nozzle 71 along the central axis of the porous support was 5 cm / sec. The number of scans was 12. The number of scans refers to the number of times the tip of the nozzle 71 (the nozzle 711) passed through a position facing the same point on one surface of the porous support. In this manner, the membrane structure according to Example 1 was obtained.

[0125] Examples 2 to 7 Film structures were produced in the same manner as in Example 1, except that the constituent materials and particle sizes of the first particles and second particles were changed as shown in Table 3.

[0126] Comparative Example 1 A porous support was prepared in the same manner as in Example 1. Zeolite powder (LTA type) having an average particle size of 300 nm was prepared as the first particles. Approximately 3 g of the zeolite powder (LTA type) was rubbed by hand onto the outer peripheral surface (one side) of the porous support to adhere it as seed crystals.

[0127] 3.2 g of sodium hydroxide was added to 18 g of water and stirred to obtain an aqueous sodium hydroxide solution. 4.3 g of aluminum hydroxide was added to the aqueous sodium hydroxide solution and stirred at 80°C for 1 hour to dissolve. 23.8 g of a 22% by mass aqueous sodium silicate solution was added to 23.8 g of water and stirred at 50°C for 1 hour. These two aqueous solutions were mixed and stirred at room temperature for 1 hour to obtain an aluminosilicate solution.

[0128] The porous support with the attached seed crystals was immersed vertically in an aluminosilicate liquid and allowed to stand at 80°C for 5 hours. The porous support with the membrane formed thereon was then removed, washed with water, and dried overnight at 100°C to obtain a membrane structure. (Comparative Example 2) A membrane structure was produced in the same manner as in Comparative Example 1, except that the first particles were attached to the porous support as seed crystals using the following procedure (dip coating method). Zeolite powder (LTA type) with an average particle size of 300 nm as the first particles was dispersed in water to a concentration of 0.5 g / mL to prepare a dip coating liquid. The porous support was immersed vertically in the dip coating liquid for 1 hour, and then dried at 100°C for 2 hours, thereby attaching the first particles to the porous support as seed crystals.

[0129] 2. Measurement and Test [X-ray Diffraction (XRD) Measurement]

[0130] X-ray diffraction measurements were performed on the film, the first particles, and the second particles. For the X-ray diffraction measurements, an X-ray diffractometer (PANanalytical, "X'PertPro MPD") was used, and measurements were performed using the focusing method. A sealed X-ray tube was used as the target, and CuKα characteristic X-rays (Kα1 wavelength (λ) = 1.54056 Å (0.154056 nm), Kα2 wavelength (λ) = 1.54439 Å (0.154439 nm), Kα2 ratio = 0.50000) were used for diffraction. The diffractometer had an automatic variable slit set to 1 mm (irradiation width) and a lateral divergence mask set to 10 mm (irradiation width). The goniometer radius was 240 mm.

[0131] Thereafter, the prepared sample of the object to be measured was irradiated with X-rays under conditions of a tube voltage of 45 kV and a tube current of 40 mA. The measurement was performed with the goniometer scanning axis set to θ / 2θ, the scanning angle set to a range of 5° to 70°, a scanning speed of 2.5° / min, and a measurement step of 0.01°. The measurement was performed in the atmosphere at room temperature. After the measurement was completed, the data obtained was analyzed without undergoing a separation process for Kα1 and Kα2. Software (High Score, manufactured by PANanalytica) was used for the data analysis.

[0132] [Measurement of surface roughness (arithmetic mean roughness Ra) and surface roughness (maximum height roughness Rz)] Using a surface profiler conforming to JIS B0651: 2001 (ISO3274: 1996), in accordance with JIS B0601: 2013 (ISO4287: 1997), the surface roughness (arithmetic mean roughness Ra) of one side of the porous support before film formation, and the surface roughness (arithmetic mean roughness Ra) and surface roughness (maximum height roughness Rz) of the outermost surface of the film formed on one side were measured. The measurement needle of the surface profiler (Tokyo Seimitsu Co., Ltd., "SURFCOM130A") was placed in contact with one side of the porous support or the outermost surface of the film, and the needle was swept 1 cm to measure the surface roughness (arithmetic mean roughness Ra) or surface roughness (maximum height roughness Rz). The arithmetic average of the measurement results at three different locations on one surface or the outermost surface was obtained as the surface roughness (arithmetic average roughness Ra) or surface roughness (maximum height roughness Rz) of each example and comparative example.

[0133] [Measuring the average thickness of the membrane] The average thicknesses T1 and T2 [μm] of the first and second portions of the membrane were measured at five locations on the cross section of the membrane structure and calculated by arithmetically averaging the measured thicknesses. The five locations were selected to be at least 20 μm apart in the in-plane direction of the membrane. Furthermore, when measuring at each location, the thickness of the first portion and the thickness of the second portion were measured so that they were aligned on the same line in the thickness direction of the membrane (membrane structure). The first portion refers to the portion of the membrane that penetrates the porous support, and the second portion refers to the portion of the membrane excluding the first portion.

[0134] To identify the interface between the porous support and the membrane, elemental analysis was performed on the measurement area using a scanning electron microscope (SEM)-energy dispersive X-ray spectroscopy (EDX). The measurement area was set to 10 μm along the in-plane direction of the membrane structure and 1 μm along the thickness direction of the membrane structure in the microstructural observation of the cross section of the membrane structure. Then, at each of the five locations where the thickness of the first portion and the thickness of the second portion were measured, the measurement area was moved from the outermost surface of the membrane toward the porous support 2 side. At this time, the measurement areas before and after each movement were moved so as not to overlap with each other. Then, a graph of each component detected by elemental analysis was created, and the location where the composition of the most frequently detected component changed was identified as the interface between the porous support and the membrane. Then, thickness measurements were performed based on the interface.

[0135] [Observation of Cross-Sectional Microstructure] (Obtaining the Ratio of the Area of ​​the Second Region to the Area of ​​the First Region) The cross-sectional microstructure of the film was observed using a scanning electron microscope (SEM)-energy dispersive X-ray spectroscopy (EDX) device ("S-4800" manufactured by Hitachi High-Technologies Corporation). For Examples 1, 2, and 5 to 7, the area (total area) S1 of the first region and the area (total area) S2 of the second region were measured based on the color density of the cross-sectional image of the film at any point in the in-plane direction obtained by SEM. Figure 9 is an SEM image showing the cross section of the film obtained in Example 1. In Figure 9, the light-colored areas are titanium oxide, i.e., the second region 34 composed of the second material.

[0136] On the other hand, for Examples 3 and 4, the area S1 of the first region and the area S2 of the second region were measured based on an elemental mapping image of aluminum of the cross section of the membrane at an arbitrary location in the in-plane direction. The brightness of the first region and the second region in the elemental mapping image differs due to the difference in Si / Al ratio between the first substance and the second substance. Based on this difference in brightness, the first region and the second region could be distinguished. As the cross-sectional image of the membrane used for measuring the areas S1 and S2, one cross-sectional image of a range of 1 μm in the thickness direction × 10 μm in the in-plane direction was used. The accelerating voltage during image acquisition was 1.0 kV, and the magnification was 50,000 times. Furthermore, as the field of view of the cross-sectional image, a region where the proportion of the porous support in the entire image was less than 10% and the proportion of the membrane was more than 50% was selected. Of the locations where the main component of the second region was observed, a region with an area of ​​20 nm ２ The above region was recognized as the second region. Then, based on the obtained areas S1 and S2, the ratio (S2 / S1) of the area S2 of the second region to the area S1 of the first region was calculated.

[0137] (Ellipse fitting of the second region) Using one of the cross-sectional images obtained by SEM or SEM-EDX, feature extraction was performed by particle extraction using image processing software ("ImageJ"). In the image, the area of ​​the area where the main component of the second region was observed was 20 nm ２These regions were identified as second regions. Ellipse fitting was used to extract features. During this process, processes to complement defects in the film and to remove noise from the image were performed as needed within the range required for feature extraction. For each second region, the angle θ between the thickness direction and the major axis direction of the ellipse fitting was obtained. The percentage of the total number of second regions was calculated for large-angle regions with an angle θ of more than 20°, and the percentage of the total number of small-angle regions with an angle θ of 20° or less. Furthermore, for each large-angle region and small-angle region, the length in the major axis direction and the ratio of the length in the major axis direction to the length in the minor axis direction were obtained. The minimum value of the length in the major axis direction in the large-angle region (minimum major axis), the minimum value of the ratio of the length in the major axis direction to the length in the minor axis direction in the large-angle region (minimum major axis / minor axis), the maximum value of the length in the major axis direction in the small-angle region (maximum major axis), and the maximum value of the ratio of the length in the major axis direction to the length in the minor axis direction in the small-angle region (maximum major axis / minor axis) were obtained.

[0138] [Selective Water Permeation Separation Test] A test was conducted to selectively permeate and separate water from a 50°C water / ethanol aqueous solution (10 / 90 mass%), which was a liquid to be separated (mixed fluid), by a pervaporation method. Specifically, the test was conducted using a water permeation separation test device 1000 shown in Figure 10. Figure 10 is a schematic diagram showing the water permeation separation test device.

[0139] A test container 1001 was filled with a liquid to be separated 1002, and the outer circumferential surface of the test container 1001 was heated by a heater 1003 so that the liquid to be separated 1002 reached 50° C. The membrane structure 1′ of the example and comparative example was placed in the test container 1001 filled with the liquid to be separated 1002, and its outer circumferential surface (one side) was brought into contact with the liquid to be separated 1002.

[0140] The pressure in the cavity of the membrane structure 1' was reduced by a vacuum pump 1008 so that the pressure in the cavity was 200 Pa or less. The pressure in the cavity was monitored using a pressure gauge 1007. A pressure difference was generated between the cavity and the outer peripheral surface (one side) with which the liquid to be separated 1002 was in contact, and this pressure difference caused the water molecules to be separated in the liquid to be separated 1002 to permeate and vaporize through the membrane structure 1'. At this time, the permeation of the water molecules creates a concentration gradient in the liquid to be separated 1002 near the outermost surface of the membrane (the water concentration is low near the outermost surface), but the concentration gradient was quickly eliminated by performing the test while stirring the liquid to be separated 1002 with a stirrer 1004 and a stirrer bar 1005.

[0141] The water molecules that permeated the membrane structure 1' passed through the liquid sending pipe 1006 and were collected as permeated liquid in the permeated liquid collecting trap 1009. Two permeated liquid collecting traps 1009 were provided, and the permeated liquid collecting traps 1009 were switched using valves V1 to V4. After 60 minutes had elapsed since the start of depressurization, the permeated amount (g / m) was calculated from the weight of the liquid collected in the permeated liquid collecting trap 1009. ２ The water content of the collected liquid was then calculated using the Karl Fischer method.

[0142] 3. Results The results of the X-ray diffraction measurement are shown in FIG. 11, with Example 3 as a representative example. FIG. 11 shows the results of the X-ray diffraction measurement for Example 3. As shown in FIG. 11, it was possible to confirm that the film was a composite film containing first particles and second particles. Other measurement results for Examples 1 to 7 and Comparative Examples 1 and 2 are summarized in Tables 3 and 4 below. Table 3 mainly shows the conditions of the powder, porous support, etc. before film formation, and Table 4 shows the measurement results of the film structure after film formation.

[0143]

[0144]

[0145] As shown in Table 3, in each example, a separation membrane structure 1 having a composite membrane with high uniformity and homogeneity as a separation membrane could be manufactured. Furthermore, in each example, the majority of the second regions were elongated large-angle regions, with a few small-angle regions with small aspect ratios. Examples with a small proportion of small-angle regions were particularly excellent in selective water permeation and separation capabilities. On the other hand, in each comparative example, it was not possible, in principle, to produce a membrane having second regions scattered in the thickness direction. Furthermore, the amount of water permeation was limited.

[0146] 1: Separation membrane structure, 2: Porous support, 20: Particle, 21: One surface, 3: Separation membrane, 3a: First particle, 3a': Component derived from first particle, 3b: Second particle, 3b': Component derived from second particle, 31: First portion, 32: Second portion, 321: Outermost surface, 33: First region, 34: Second region, 34a: Large angle region, 34b: Small angle region, 4: Manufacturing apparatus, 5: Chamber, 6: Support mechanism, 61: Support rod, 62: Motor, 7: Jet mechanism, 71: Nozzle, 711: Jet outlet, 72: Gas cylinder, 73: Transfer pipe, 74: Mass flow controller, 75: Energizer Aerosol generator, 78: moving mechanism, 8: pressure reducing mechanism, 81: pump, 9: control means, 91: calculation unit, 92: memory unit, 100: separation device, 200: housing, 201: internal space, 1000: permeation separation test device, 1001: test vessel, 1002: liquid to be separated, 1003: heater, 1004: stirrer, 1005: stirrer bar, 1006: liquid transfer tube, 1007: pressure gauge, 1008: pressure reducing pump, 1009: permeate collection trap, P: powder, T1: average thickness, T2: average thickness, V1: valve, V2: valve, V3: valve, V4: valve

Claims

1. A separation membrane structure comprising: a porous support; and a separation membrane; the separation membrane is provided on one surface of the porous support; and comprises a first substance which is a substance having pores or a component derived from the substance having pores; and a second substance which differs from the first substance in at least one of chemical composition and crystal structure; and the second substance is scattered throughout the thickness of the separation membrane.

2. A separation membrane structure according to claim 1, wherein the second substance is further scattered in the in-plane direction of the separation membrane.

3. A separation membrane structure according to claim 1 or 2, wherein in a cross section of the separation membrane, the ratio of the total area of ​​the one or more second regions made of the second material to the area of ​​the first region made of the first material is 0.1 or more and 1 or less.

4. A separation membrane structure according to claim 3, wherein the proportion of small-angle regions, in which the angle between the major axis direction and the thickness direction of the separation membrane as determined by ellipse fitting is 20° or less, to the total number of the one or more second regions is 15% or less.

5. A separation membrane structure according to claim 4, wherein the length of the small-angle region in the major axis direction is 100 nm or less.

6. A separation membrane structure according to claim 5, wherein the ratio of the length in the major axis direction to the length in the minor axis direction by ellipse fitting of the small angle region is 4 or less.

7. A separation membrane structure according to any one of claims 1 to 6, wherein the surface roughness (arithmetic mean roughness Ra) of the surface of the separation membrane opposite to the porous support is 1.3 μm or less.

8. A separation membrane structure according to any one of claims 1 to 7, wherein the surface roughness (maximum height roughness Rz) of the surface of the separation membrane opposite to the porous support is 10 μm or less.

9. A separation membrane structure according to any one of claims 1 to 8, wherein when the average thickness of a first portion of the separation membrane embedded in the porous support is T1 [μm] and the average thickness of a second portion of the separation membrane excluding the first portion is T2 [μm], T1 / T2 is 1 / 6 or less.

10. A separation membrane structure according to claim 9, wherein the average thickness T1 is 1 μm or less.

11. A separation membrane structure according to claim 9 or 10, wherein the average thickness T2 is 0.5 μm or more and 10 μm or less.

12. The separation membrane structure according to any one of claims 1 to 11, wherein the first substance is a zeolite, a metal-organic framework, a metal oxide, a metal nitride, or a mixture thereof.

13. A separation membrane structure according to any one of claims 1 to 12, wherein the second substance is a zeolite, a metal-organic framework, a metal oxide, a metal nitride, or a mixture thereof.

14. A separation membrane structure according to any one of claims 1 to 13, wherein the first substance is a zeolite, and the second substance is a metal oxide.

15. A separation membrane structure according to any one of claims 1 to 14, wherein the first substance and the second substance are both zeolites, and the first substance and the second substance have different crystal structures.

16. A separation membrane structure according to any one of claims 1 to 15, wherein the first substance and the second substance are both zeolite, and the first substance and the second substance have different silicon / aluminum ratios.

17. A method for producing a separation membrane structure according to any one of claims 1 to 16, comprising the steps of: preparing powder containing the first substance and the second substance and the porous support; and spraying the powder onto one surface of the porous support to form the separation membrane on the one surface, thereby obtaining the separation membrane structure.

18. A method for producing a separation membrane structure according to claim 17, wherein in the step of obtaining the separation membrane structure, the powder is sprayed onto the one surface of the porous support by an aerosol deposition method.

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