Gas separation membrane, method for producing gas separation membrane, and gas separation device
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-22
- Publication Date
- 2026-03-27
Smart Images
Figure CN121732003A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a gas separation membrane, a method for manufacturing a gas separation membrane, and a gas separation apparatus. BACKGROUND
[0002] In order to achieve carbon neutrality (i.e., the amount of carbon dioxide emitted is the same as the amount of carbon dioxide absorbed) and carbon negative (i.e., more carbon dioxide is absorbed than emitted), technologies are being studied that intake and recover carbon dioxide emitted from thermal power plants and boiler facilities and the like and carbon dioxide in the atmosphere. As this technology, a membrane separation method using a gas separation membrane to separate carbon dioxide is known.
[0003] For example, in Patent Literature 1, a gas separation membrane that selectively and separates carbon dioxide from a mixed gas containing carbon dioxide is disclosed, which has a porous layer, a first resin layer, and a second resin layer. The first resin layer is provided between the porous layer and the second resin layer, is composed of an organic polysiloxane, and has a higher porosity than the second resin layer. In addition, the second resin layer is composed of an organic polysiloxane and is chemically bonded to the first resin layer.
[0004] Such a gas separation membrane has high gas permeability to carbon dioxide and excellent mechanical strength.
[0005] PRIOR ART DOCUMENTS
[0006] PATENT LITERATURE
[0007] Patent Literature 1: Japanese Patent Application Publication No. 2024-042578
[0008] In the membrane separation method, energy for forming a pressure difference sandwiching the gas separation membrane is required. In order to reduce the consumption of this energy, it is necessary to further improve the gas selectivity to carbon dioxide and the degree of gas permeation without impairing the mechanical strength of the gas separation membrane. SUMMARY
[0009] The gas separation membrane according to an application example of the present application is,
[0010] A gas separation membrane that selectively and separates carbon dioxide from a mixed gas containing carbon dioxide, the gas separation membrane comprising:
[0011] a separation layer composed of a high molecular material and having a function of selectively and separating carbon dioxide; and
[0012] a porous substrate having a first porous layer in contact with the separation layer and a second porous layer provided on the side of the first porous layer opposite to the separation layer,
[0013] when a layer thickness of the first porous layer is set to T1, an average pore diameter is set to d1, an opening ratio is set to A1, and a maximum height roughness of a surface facing the separation layer is set to R1,
[0014] the layer thickness T1 is 0.1 μm or more and 10.0 μm or less,
[0015] the average pore diameter d1 is 10 nm or more and 10000 nm or less,
[0016] the opening ratio A1 is 40% or more and 80% or less,
[0017] the maximum height roughness R1 is 1 nm or more and 200 nm or less,
[0018] when a layer thickness of the second porous layer is set to T2, an average pore diameter is set to d2, and an opening ratio is set to A2,
[0019] the layer thickness T2 is 10 μm or more and 1000 μm or less,
[0020] a ratio d2 / d1 of the average pore diameter d2 to the average pore diameter d1 is 1.1 or more and 10000 or less,
[0021] a ratio A2 / A1 of the opening ratio A2 to the opening ratio A1 is 1.1 or more and 2.0 or less.
[0022] The application example of the present application relates to a method for manufacturing a gas separation membrane, having:
[0023] a step of obtaining a coated film: preparing a porous substrate having a first porous layer and a second porous layer laminated with each other, and supplying a raw material liquid in contact with the first porous layer, thereby obtaining a coated film; and
[0024] a step of obtaining a separation layer: performing an energy-imparting treatment on the coated film, thereby obtaining a separation layer composed of a high molecular material and having a function of selectively and separating carbon dioxide,
[0025] when a layer thickness of the first porous layer is set to T1, an average pore diameter is set to d1, an opening ratio is set to A1, and a maximum height roughness of a surface facing the separation layer is set to R1,
[0026] the layer thickness T1 is 0.1 μm or more and 10.0 μm or less,
[0027] the average pore diameter d1 is 10 nm or more and 10000 nm or less,
[0028] the opening ratio A1 is 40% or more and 80% or less,
[0029] The maximum height roughness R1 is 1 nm or more and 200 nm or less,
[0030] When the layer thickness of the second porous layer is T2, the average pore diameter is d2, and the opening ratio is A2,
[0031] The layer thickness T2 is 10 μm or more and 1000 μm or less,
[0032] The ratio d2 / d1 of the average pore diameter d2 to the average pore diameter d1 is 1.1 or more and 10000 or less,
[0033] The ratio A2 / A1 of the opening ratio A2 to the opening ratio A1 is 1.1 or more and 2.0 or less.
[0034] The gas separation device according to an application example of the present application includes:
[0035] The gas separation membrane according to an application example of the present application includes:
[0036] A fixing portion that fixes the gas separation membrane and forms an internal space on the porous substrate side of the gas separation membrane; and
[0037] An exhaust portion that depressurizes the internal space in a manner that an external space on the separation layer side of the gas separation membrane becomes a negative pressure. BRIEF DESCRIPTION OF DRAWINGS
[0038] Figure 1 is a cross-sectional view that schematically shows a gas separation membrane according to an embodiment.
[0039] Figure 2 is a cross-sectional view that schematically shows a gas separation membrane according to an embodiment.
[0040] Figure 3 is a schematic view for explaining a method of measuring an average pore diameter in an observation image of a cross section of a first porous layer.
[0041] Figure 4 is a schematic view for explaining a method of measuring an opening ratio in an observation image of a cross section of a first porous layer.
[0042] Figure 5 is a cross-sectional view that schematically shows a gas separation membrane (a gas separation membrane according to a modification) including a porous substrate.
[0043] Figure 6 is a process diagram showing a configuration of a method of manufacturing a gas separation membrane according to an embodiment.
[0044] Figure 7is a cross-sectional view showing the schematic structure of a gas separation device according to the embodiment.
[0045] Figure 8 Table 1 is a table showing the structure of the gas separation membrane of each example and the evaluation results of the gas separation membrane.
[0046] Figure 9 Table 2 is a table showing the structure of the gas separation membrane of each comparative example and the evaluation results of the gas separation membrane.
[0047] Explanation of Reference Numerals
[0048] 1: gas separation membrane; 2: separation layer; 3: porous substrate; 4: particle; 5: gas separation device; 30: porous sheet; 31: first porous layer; 32: second porous layer; 33: through-hole; 51: porous plate; 52: fixing portion; 53: pipe; 54: exhaust portion; 301: upper surface; 302: lower surface; 310: upper surface; 312: air hole; 322: air hole; 522: inner space; 524: outer space; Al: opening ratio; A2: opening ratio; Gl: mixed gas; G2: permeated gas; Rl: maximum height roughness; S102: coating film forming step; S104: energy imparting step; T0: layer thickness; Tl: layer thickness; T2: layer thickness; a0: area; al: area; dl: average pore diameter; dl-1: inner diameter; dl-2: inner diameter; dl-3: inner diameter; d2: average pore diameter. DETAILED DESCRIPTION
[0049] Hereinafter, a gas separation membrane, a method for manufacturing a gas separation membrane, and a gas separation device according to the present application will be described in detail based on the embodiments shown in the drawings.
[0050] 1. Outline of gas separation membrane
[0051] First, the structure of the gas separation membrane according to the embodiment will be described.
[0052] Figure 1 and Figure 2 are cross-sectional views schematically showing a gas separation membrane 1 according to the embodiment. Note that, in the present application, the X axis, the Y axis, and the Z axis are set as three axes orthogonal to each other, and are respectively indicated by arrows. In addition, the base end side of the arrow for indicating each axis is set to be "negative", and the front end side is set to be "positive". Figure 1 and Figure 2 In the gas separation membrane 1 shown in
[0053] In the gas separation membrane 1 shown in Figure 1 Figure 2 In the gas separation membrane 1 shown inFigure 1 and Figure 2 In the gas separation membrane 1 shown in FIG. 1, carbon dioxide is separated by permeating from the upper side to the lower side.
[0054] Figure 1 and Figure 2 The gas separation membrane 1 shown in FIG. 1 is used to permeate and separate carbon dioxide from a mixed gas containing carbon dioxide. Figure 1 and Figure 2 The gas separation membrane 1 shown in FIG. 1 has a separation layer 2 and a porous substrate 3 stacked in the Z-axis direction. The separation layer 2 is composed of a polymer and has a function of selectively separating carbon dioxide. The porous substrate 3 is a multilayer substrate in a sheet shape extending along the X-Y plane, and has a first porous layer 31 that is in contact with the separation layer 2, and a second porous layer 32 provided on the side opposite to the separation layer 2 of the first porous layer 31. Note that there can be any member between the first porous layer 31 and the second porous layer 32.
[0055] In addition, the porous substrate 3 has the following structure.
[0056] First, the layer thickness of the first porous layer 31 is set to T1, the average pore diameter is set to d1, the opening ratio is set to A1, and the maximum height roughness of the upper surface 310 (the surface facing the separation layer 2) is set to R1. At this time, the layer thickness T1 is 0.1 μm or more and 10.0 μm or less, the average pore diameter d1 is 10 nm or more and 10,000 nm or less, the opening ratio A1 is 40% or more and 80% or less, and the maximum height roughness R1 is 1 nm or more and 200 nm or less.
[0057] In addition, the layer thickness of the second porous layer 32 is set to T2, the average pore diameter is set to d2, and the opening ratio is set to A2. At this time, the layer thickness T2 is 10 μm or more and 1,000 μm or less.
[0058] Further, the ratio of the average pore diameter d2 to the average pore diameter d1 is set to the average pore diameter ratio d2 / d1, and the ratio of the opening ratio A2 to the opening ratio A1 is set to the opening ratio ratio A2 / A1. At this time, the average pore diameter ratio d2 / d1 is 1.1 or more and 10,000 or less, and the opening ratio ratio A2 / A1 is 1.1 or more and 2.0 or less.
[0059] According to such a structure, it is possible to realize a gas separation membrane 1 that has a high gas selectivity ratio and a high gas permeation degree for carbon dioxide and has sufficient mechanical strength.
[0060] Note that in FIG. 6, an image of the porous substrate 3 when the average pore diameter ratio d2 / d1 of the porous substrate 3 is relatively large in the above range is schematically shown. Figure 1 Note that in FIG. 6, an image of the porous substrate 3 when the average pore diameter ratio d2 / d1 of the porous substrate 3 is relatively large in the above range is schematically shown.
[0061] In addition, in Figure 2 In the drawing, an image of the porous substrate 3 is schematically shown when the ratio A2 / A1 of the opening ratio of the porous substrate 3 is relatively large within the above range.
[0062] Note that the gas separation membrane according to the present application can be in a form other than Figure 1 and Figure 2 a spiral shape, a tube shape, a hollow fiber shape, or the like.
[0063] 1.1 Porous substrate
[0064] The porous substrate 3 is in a sheet shape, and supports the separation layer 2. Thus, even when the separation layer 2 does not have sufficient mechanical properties, by supporting the separation layer 2 with the porous substrate 3, a gas separation membrane 1 having excellent mechanical properties can be realized.
[0065] As described above, the porous substrate 3 has a first porous layer 31 and a second porous layer 32. As described above, the first porous layer 31 is provided at a position in contact with the separation layer 2, and supports the separation layer 2. The second porous layer 32 is provided below the first porous layer 31.
[0066] 1.1.1. First porous layer
[0067] The first porous layer 31 is composed of a porous material. The porous material is a material having a plurality of pores 312, and has a good gas permeation degree.
[0068] As the porous material constituting the first porous layer 31, for example, ceramic materials, metal materials, and high molecular materials can be listed. In addition, the porous material can be a composite material of these materials and other materials.
[0069] As the ceramic material, for example, alumina, cordierite, mullite, silicon carbide, silicon oxide, and zirconia can be listed.
[0070] As the metal material, for example, stainless steel, copper alloy, aluminum alloy, and titanium alloy can be listed.
[0071] As the high molecular material, for example, polyolefin-based resins such as polyethylene and polypropylene; fluorine-containing resins such as polytetrafluoroethylene, polyvinyl fluoride, and polyvinylidene fluoride; polystyrene, cellulose, cellulose acetate, cellulose nitrate, polycarbonate, polyurethane, polyacrylonitrile, polyphenylene ether, polysulfone, polyethersulfone, polyimide, polyaramide, nylon, and polysiloxane can be listed.
[0072] In addition, the first porous layer 31 can also be a filter of a continuous bubble structure. The filter of a continuous bubble structure is also called an absolute filter, is continuous from one face to the other face having a front and back relationship with each other, and has pores 312 independent of each other.
[0073] The layer thickness T1 of the first porous layer 31 is 0.1 μm or more and 10.0 μm or less, preferably 0.3 μm or more and 7.0 μm or less, and more preferably 1.0 μm or more and 5.0 μm or less. If the layer thickness T1 is within the range, the first porous layer 31 having a good gas permeation degree and necessary and sufficient mechanical strength can be obtained.
[0074] Note that when the layer thickness T1 of the first porous layer 31 is lower than the lower limit value, the mechanical strength of the first porous layer 31 decreases, and breakage or the like can occur. In this case, the separation layer 2 cannot be sufficiently supported by the porous base material 3, and the gas selectivity of the gas separation membrane 1 can decrease. On the other hand, when the layer thickness T1 of the first porous layer 31 is higher than the upper limit value, the pressure loss when a gas passes through the pores 312 included in the first porous layer 31 becomes large, and the gas permeation degree of the first porous layer 31 decreases.
[0075] Note that the layer thickness T1 of the first porous layer 31 is obtained as follows. First, the first porous layer 31 is subjected to cross-section processing based on focused ion beam processing or the like. Next, the obtained cross-section is observed with a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM). Next, the range of the first porous layer 31 is extracted based on the contrast of the observation image. Next, the thickness of the extracted first porous layer 31 is measured at 5 points. Then, the average value of the measured thicknesses is taken as the layer thickness T1 of the first porous layer 31.
[0076] The average pore diameter d1 of the first porous layer 31 is 10 nm or more and 10,000 nm or less, preferably 20 nm or more and 1,000 nm or less, and more preferably 30 nm or more and 500 nm or less. If the average pore diameter d1 is within the range, the first porous layer 31 having a good gas permeation degree and necessary and sufficient mechanical strength can be obtained. In addition, by moderately permeating the separation layer 2 into the pores 312 of the first porous layer 31, the adhesiveness and the coverage of the separation layer 2 can be improved. As a result, the gas selectivity of the separation layer 2 is improved.
[0077] Note that when the average pore diameter dl of the first porous layer 31 is lower than the lower limit value, the pressure loss when a gas passes through the pores 312 included in the first porous layer 31 becomes large, and the gas permeability of the first porous layer 31 decreases. In addition, because the permeation of the separation layer 2 is inhibited, the gas selectivity of the separation layer 2 decreases. On the other hand, when the average pore diameter dl of the first porous layer 31 is higher than the upper limit value, the mechanical strength of the first porous layer 31 decreases, and breakage or the like can occur. In this case, the separation layer 2 cannot be sufficiently held by the porous base material 3, and the gas selectivity of the gas separation membrane 1 can decrease. In addition, because the holding property of the separation layer 2 decreases, the coverage of the separation layer 2 can decrease, or the separation layer 2 can easily break.
[0078] Note that the average pore diameter dl of the first porous layer 31 is calculated as follows. Figure 3 is a schematic view for explaining a method of measuring the average pore diameter dl in an observation image of a cross section of the first porous layer 31.
[0079] First, the first porous layer 31 is subjected to cross section processing based on focused ion beam processing or the like. Next, the obtained cross section is observed with a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM). Figure 3 is an example of the observation image thus obtained. Next, based on the contrast of the observation image, the range of the first porous layer 31 and the pores 312 that pass through the range in the thickness direction are extracted. Next, the inner diameters of three places in the thickness direction (the inner diameter dl-1 of the side closest to the separation layer 2, the inner diameter dl-2 of the central portion, and the inner diameter dl-3 of the side closest to the second porous layer 32) are measured for the extracted pores 312. Next, the same inner diameter measurement is performed for five pores 312. Then, the average of the 15 data obtained is taken as the average pore diameter dl of the first porous layer 31.
[0080] The opening ratio Al of the first porous layer 31 is 40% or more and 80% or less, and is preferably 50% or more and 70% or less. If the opening ratio Al is within the range, the first porous layer 31 having a good gas permeability and necessary and sufficient mechanical strength can be obtained.
[0081] Note that when the opening ratio Al of the first porous layer 31 is lower than the lower limit value, the pressure loss when a gas passes through the pores 312 included in the first porous layer 31 becomes large, and the gas permeability of the first porous layer 31 decreases. On the other hand, when the opening ratio Al of the first porous layer 31 is higher than the upper limit value, the mechanical strength of the first porous layer 31 decreases, and breakage or the like can occur. In this case, the separation layer 2 cannot be stably supported by the porous base material 3, and the gas selectivity of the gas separation membrane 1 can decrease.
[0082] Note that the opening ratio A1 of the first porous layer 31 is calculated as follows. Figure 4 is a schematic view for explaining a method of measuring the opening ratio A1 in an observation image of a cross section of the first porous layer 31.
[0083] First, the first porous layer 31 is subjected to cross section processing based on focused ion beam processing or the like. Next, the obtained cross section is observed with a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM). Figure 4 is an example of the observation image thus obtained. Next, after the observation image is subjected to a binary processing, based on the contrast, the range of the first porous layer 31 and the pores 312 that pass through the range in the thickness direction are extracted. Next, in the observation image, the area a1 of the pores 312 and the area a0 other than the pores 312 of the first porous layer 31 are measured. Then, the area ratio is calculated with the calculation formula a1 / a0 x 100, and the calculated result is taken as the opening ratio A1 of the first porous layer 31.
[0084] The maximum height roughness R1 of the upper surface 310 (a surface facing the separation layer 2) of the first porous layer 31 is 1 nm or more and 200 nm or less, preferably 3 nm or more and 150 nm or less, and more preferably 5 nm or more and 120 nm or less. If the maximum height roughness R1 of the upper surface 310 is within the range, the coverage of the separation layer 2 can be sufficiently improved. In addition, it is possible to suppress the formation of the first porous layer 31 from becoming difficult. Note that when the maximum height roughness R1 of the upper surface 310 of the first porous layer 31 is lower than the lower limit value, the formation of the first porous layer 31 becomes difficult. On the other hand, when the maximum height roughness R1 of the upper surface 310 of the first porous layer 31 is higher than the upper limit value, the continuity of the separation layer 2 formed on the upper surface 310 is impaired, and the coverage of the separation layer 2 decreases.
[0085] Note that the maximum height roughness R1 of the upper surface 310 of the first porous layer 31 is calculated as follows.
[0086] First, the first porous layer 31 is set to a surface roughness measuring device with the upper surface 310 of the first porous layer 31 as an observation target surface. The measuring device uses, for example, a laser microscope equipped with a white light interferometer. As such a laser microscope, for example, there can be cited the VK-X3000 manufactured by KEYENCE Corporation. Then, the shape of the upper surface 310 is scanned at a magnification of 50 times. Thereby, an image containing information on the concave-convex shape of the upper surface 310 is obtained. Next, within the image, the highest point and the lowest point are determined in a range other than the pores 312 of the first porous layer 31. Next, the height difference between the two points is calculated, which is taken as the maximum height roughness Rl. That is, the maximum height difference in the portion other than the pores 312 is found from the measurement result of the concave-convex shape of the upper surface 310, and taken as the maximum height roughness Rl.
[0087] 1.1.2. Second Porous Layer
[0088] The second porous layer 32 is composed of a porous material.
[0089] As the porous material constituting the second porous layer 32, a material cited as the porous material constituting the first porous layer 31 described above can be appropriately selected. Note that the porous material constituting the second porous layer 32 can be the same as or different from the porous material constituting the first porous layer 31. In addition, the second porous layer 32 can also be a filter of a continuous bubble structure.
[0090] The layer thickness T2 of the second porous layer 32 is 10 μm or more and 1000 μm or less, preferably 10 μm or more and 200 μm or less, and more preferably 30 μm or more and 200 μm or less. If the layer thickness T2 is within the range, the second porous layer 32 having a good gas permeability and a necessary and sufficient mechanical strength can be obtained. Note that when the layer thickness T2 of the second porous layer 32 is lower than the lower limit value, the mechanical strength of the second porous layer 32 decreases, and damage or the like can occur. In this case, the separation layer 2 cannot be sufficiently held by the porous base material 3, and the gas selectivity of the gas separation membrane 1 can decrease. On the other hand, when the layer thickness T2 of the second porous layer 32 is higher than the upper limit value, the pressure loss when a gas passes through the pores 322 included in the second porous layer 32 becomes large, and the gas permeability of the second porous layer 32 decreases.
[0091] Note that the method of measuring the layer thickness T2 of the second porous layer 32 is the same as the method of measuring the layer thickness Tl of the first porous layer 31.
[0092] The average pore diameter d2 of the second porous layer 32 is preferably 10 nm or more and 10,000 nm or less, more preferably 20 nm or more and 5,000 nm or less, and further preferably 30 nm or more and 3,000 nm or less. If the average pore diameter d2 is within the range, the second porous layer 32 having a good gas permeance and necessary and sufficient mechanical strength can be obtained. Note that when the average pore diameter d2 of the second porous layer 32 is lower than the lower limit value, the pressure loss when the gas passes through the second porous layer 32 becomes large, and the gas permeance of the second porous layer 32 can decrease. On the other hand, when the average pore diameter d2 of the second porous layer 32 is higher than the upper limit value, the mechanical strength of the second porous layer 32 decreases, and breakage or the like can occur.
[0093] Note that the method of measuring the average pore diameter d2 of the second porous layer 32 is the same as the method of measuring the average pore diameter d1 of the first porous layer 31.
[0094] The opening ratio A2 of the second porous layer 32 is preferably 40% or more and 80% or less, and more preferably 50% or more and 70% or less. If the opening ratio A2 is within the range, the second porous layer 32 having a good gas permeance and necessary and sufficient mechanical strength can be obtained. Note that when the opening ratio A2 of the second porous layer 32 is lower than the lower limit value, the pressure loss when the gas passes through the second porous layer 32 becomes large, and the gas permeance of the second porous layer 32 can decrease. On the other hand, when the opening ratio A2 of the second porous layer 32 is higher than the upper limit value, the mechanical strength of the second porous layer 32 decreases, and breakage or the like can occur.
[0095] Note that the method of measuring the opening ratio A2 of the second porous layer 32 is the same as the method of measuring the opening ratio A1 of the first porous layer 31.
[0096] 1.1.3. Relationship between the structures of the first porous layer and the second porous layer
[0097] Each of the structures of the first porous layer 31 and the second porous layer 32 satisfies the following relationship.
[0098] The ratio T2 / T1 of the layer thickness T2 to the layer thickness T1 is preferably 1 or more and 10,000 or less, more preferably 2 or more and 2,000 or less, and further preferably 5 or more and 1,000 or less. If the ratio T2 / T1 of the layer thicknesses is within the range, the function of the first porous layer 31 to support the separation layer 2 and the function of the second porous layer 32 to have gas permeability can be both taken into account. Thus, the porous base material 3 in which even a thin separation layer 2 can be sufficiently supported and the gas permeance is sufficiently high can be realized. As a result, the gas separation membrane 1 in which the high gas selectivity and the high gas permeance are both taken into account can be realized.
[0099] Note that when the layer thickness ratio T2 / T1 is lower than the lower limit value, the layer thickness T2 becomes relatively too thin, or the layer thickness T1 becomes relatively too thick, and thus the balance is broken, and it can be difficult to achieve the above-described functions. On the other hand, when the layer thickness ratio T2 / T1 is higher than the upper limit value, the layer thickness T1 becomes relatively too thin, or the layer thickness T2 becomes relatively too thick, and thus the balance is broken, and it can be difficult to achieve the above-described functions.
[0100] The ratio d2 / d1 of the average pore diameter d2 to the average pore diameter d1 is 1.1 or more and 10,000 or less, preferably 1.5 or more and 1,000 or less, and more preferably 2.0 or more and 500 or less. If the ratio d2 / d1 of the average pore diameters is within the range, the separation layer 2 is moderately permeated into the pores 312 of the first porous layer 31, and even if the separation layer 2 is thin, the adhesiveness and the coverage can be improved, and the gas permeability and the mechanical strength of the second porous layer 32 can be sufficiently ensured. As a result, the gas separation membrane 1 having a high gas selectivity for carbon dioxide and a high gas permeability, and having sufficient mechanical strength can be achieved.
[0101] Note that when the ratio d2 / d1 of the average pore diameters is lower than the lower limit value, the average pore diameter d2 becomes relatively too small, or the average pore diameter d1 becomes relatively too large, and thus the balance is broken, and the gas permeability of the second porous layer 32 is reduced, or the gas separation membrane 1 is reduced in the gas selectivity by the first porous layer 31 stably holding the separation layer 2. On the other hand, when the ratio d2 / d1 of the average pore diameters is higher than the upper limit value, the average pore diameter d2 becomes relatively too large, or the average pore diameter d1 becomes relatively too small, and thus the balance is broken, and the support of the second porous layer 32 to the first porous layer 31 and the mechanical strength of the second porous layer 32 become insufficient, or the gas permeability of the first porous layer 31 is reduced or the permeation of the separation layer 2 is insufficient.
[0102] The ratio A2 / A1 of the opening ratio A2 to the opening ratio A1 is 1.1 or more and 2.0 or less, and preferably 1.3 or more and 1.8 or less. If the ratio A2 / A1 of the opening ratios is within the range, the separation layer 2 can be stably supported by the first porous layer 31, and the gas permeability required for the first porous layer 31 can be ensured, and the gas permeability and the mechanical strength of the second porous layer 32 can be sufficiently improved. As a result, the gas separation membrane 1 having a high gas selectivity for carbon dioxide and a high gas permeability, and having sufficient mechanical strength can be achieved.
[0103] Note that when the ratio of the opening ratios A2 / A1 is lower than the lower limit value, the opening ratio A2 becomes relatively too small, or the opening ratio A1 becomes relatively too large, and thus the balance is broken, resulting in a decrease in the gas permeation degree of the second porous layer 32 or a decrease in the gas selectivity of the gas separation membrane 1 due to an unstable maintenance of the separation layer 2 by the first porous layer 31. On the other hand, when the ratio of the opening ratios A2 / A1 is higher than the upper limit value, the opening ratio A2 becomes relatively too large, or the opening ratio A1 becomes relatively too small, and thus the balance is broken, resulting in an insufficient mechanical strength of the second porous layer 32 or a decrease in the gas permeation degree of the first porous layer 31.
[0104] 1.1.4. Modification of the porous base material 3
[0105] Next, the gas separation membrane according to the modification will be described.
[0106] Figure 5 is a cross-sectional view schematically showing a gas separation membrane 1 according to the modification (gas separation membrane according to the modification).
[0107] Hereinafter, the gas separation membrane 1 according to the modification will be described, but in the following description, the description will be made focusing on the difference from the gas separation membrane 1 described above, and the description thereof will be omitted for the same matters. Note that in the following description, the same reference numerals are attached to the same structures as those of the gas separation membrane 1 described above. Figure 5 Figure 1
[0108] Figure 5 The porous base material 3 shown in FIG. 1 1 is the same as the porous base material 3 shown in FIG. 1 except that the particles 4 are additionally provided. Figure 1
[0109] Figure 5 The porous base material 3 shown in FIG. 1 1 has the porous sheet 30 and the particles 4. The porous sheet 30 has an upper surface 301 (one surface) and a lower surface 302 (another surface) which have a front and back relationship with each other. In addition, the through-holes 33 which pass through from the upper surface 301 to the lower surface 302 are formed in the porous sheet 30. Further, the particles 4 are inserted into the through-holes 33.
[0110] According to such a structure, the through-holes 33 formed in the porous sheet 30 can be narrowed by the particles 4. Thereby, the opening ratio of the porous sheet 30 can be easily adjusted. In addition, even in the case where the porous sheet 30 of a single structure is used, the first porous layer 31 and the second porous layer 32 can be formed, and thus the manufacturing easiness and the cost reduction of the gas separation membrane 1 can be achieved.
[0111] In addition, in the case where the porous base material 3 shown in FIG. 1 1 is used, the first porous layer 31 and the second porous layer 32 can be formed by the same method as that of the porous base material 3 shown in FIG. 1. Figure 5 From the upper surface 301 side of the porous sheet 30, the particles 4 are inserted. Thus, Figure 5 The particles 4 shown are caught in the portion of the through air hole 33 on the upper surface 301 side, and narrow the inner diameter of the portion. Thus, the portion of the porous sheet 30 in which the particles 4 are dense becomes the first porous layer 31, and the portion in which the particles 4 are less dense becomes the second porous layer 32.
[0112] In addition, in the porous sheet 30 shown, Figure 5 In the porous sheet 30 shown, the average pore diameter is set to be smaller on the upper surface 301 side than on the lower surface 302 side. Thereby, the particles 4 are easily caught in the portion of the porous sheet 30 on the upper surface 301 side. Note that the average pore diameter of the porous sheet 30 can also be constant in the thickness direction.
[0113] As the particles 4, for example, alumina particles, silica particles, silicone particles, and the like can be cited.
[0114] The average particle diameter of the particles 4 is appropriately set in accordance with the inner diameter of the pores of the porous sheet 30, and is preferably 0.01 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less.
[0115] Note that the average particle diameter of the particles 4 refers to the particle diameter D50 at which the cumulative frequency from the small particle diameter side is 50% in the cumulative particle size distribution of the particles 4 on a volume basis, which is obtained using a laser diffraction type particle size distribution measuring device.
[0116] 1.2. Separation layer
[0117] The separation layer 2 is provided on the upper surface 310 of the first porous layer 31 of the porous substrate 3. The separation layer 2 has a function of selectively and separating carbon dioxide.
[0118] The constituent material of the separation layer 2 is a high molecular material. As the high molecular material, for example, polyolefin-based resins such as polyethylene, polypropylene, and the like; fluorine-containing resins such as polytetrafluoroethylene, polyfluoroethylene, polyvinylidene fluoride, and the like; polystyrene, cellulose, cellulose acetate, polyurethane, polyacrylonitrile, polyphenylene ether, polysulfone, polyethersulfone, polyimide, polyaromatic amide, organic polysiloxane, polyethylene terephthalate (PET), polyoxymethylene (POM), polylactic acid (PLA), and the like can be cited. In addition, the constituent material of the separation layer 2 can also be a material in which two or more of these are compounded.
[0119] Among these, the constituent material of the separation layer 2 preferably uses an organic polysiloxane. One molecule of the organic polysiloxane contains at least a unit (T unit) represented by R 1 SiO 3 / 2 R 2 R 3 SiO 2 / 2a unit represented by R 4 R 5 R 6 SiO 1 / 2 a unit represented by R 1 ~R 6 is an aliphatic hydrocarbon or a hydrogen atom. The organopolysiloxane is constituted by combining these T units, D units, and M units.
[0120] As specific examples of the organopolysiloxane, polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, a polysulfone / polyhydroxystyrene / polydimethylsiloxane copolymer, a dimethylsiloxane / methylvinylsiloxane copolymer, a dimethylsiloxane / diphenylsiloxane / methylvinylsiloxane copolymer, a methyl-3,3,3-trifluoropropylsiloxane / methylvinylsiloxane copolymer, a dimethylsiloxane / methylphenylsiloxane / methylvinylsiloxane copolymer, a vinyl-terminated diphenylsiloxane / dimethylsiloxane copolymer, a vinyl-terminated polydimethylsiloxane, an amino-terminated polydimethylsiloxane, a phenyl-terminated polydimethylsiloxane, an H-terminated polydimethylsiloxane, a dimethylsiloxane-methylhydrogenosiloxane copolymer, and the like can be given. The expression of vinyl-terminated or the like indicates that at least one terminal of the main chain included in the organopolysiloxane is substituted with a substituent such as a vinyl group. Note that, among them, a form that forms a crosslinking reactant is also included. In addition, the constituent material of the separation layer 2 can be one of them or a composite of two or more of them, and can also be a composite material in which the organopolysiloxane is a main component in terms of mass ratio and other resin components are used in combination.
[0121] Note that the organopolysiloxane has a good affinity for carbon dioxide. Therefore, the separation layer 2 including the organopolysiloxane exhibits a high gas selectivity for carbon dioxide.
[0122] Note that, as needed, an arbitrary functional group can be introduced on the surface of the upstream side of the separation layer 2 using a coupling agent or the like. By appropriately selecting the functional group, the affinity for carbon dioxide can be further improved.
[0123] The layer thickness TO of the separation layer 2 is not particularly limited, and is preferably 1 nm or more and 1000 nm or less, more preferably 3 nm or more and 800 nm or less, further preferably 5 nm or more and 500 nm or less, and particularly preferably 10 nm or more and 200 nm or less. Thus, the separation layer 2 has a good gas selectivity and a gas permeability. As a result, a gas separation membrane 1 in which the amount of energy required for separation of carbon dioxide is reduced, specifically, in which the pressure difference between the upstream side and the downstream side of the gas separation membrane 1 is reduced, can be realized. Note that when the layer thickness TO of the separation layer 2 is lower than the lower limit value, the coverage of the separation layer 2 can decrease, or the separation layer 2 can be easily broken, resulting in a decrease in the gas selectivity of the separation layer 2. On the other hand, when the layer thickness TO of the separation layer 2 is higher than the upper limit value, the gas permeability of the separation layer 2 can decrease, resulting in an increase in the amount of energy required for separation, or the flexibility of the separation layer 2 can decrease.
[0124] The layer thickness TO of the separation layer 2 is, for example, determined as an average value of the thickness at 10 points in a cross section of the gas separation membrane 1 observed under a magnifying glass. In the magnifying glass observation, for example, a scanning electron microscope (SEM), a scanning transmission electron microscope (STEM), or the like is used. Alternatively, the thickness of the separation layer 2 can be determined by depth direction analysis based on X-ray photoelectron spectroscopy, and the determined value can be used as the layer thickness TO of the separation layer 2.
[0125] 1.3. Other Structures
[0126] The gas separation membrane 1 according to the embodiment has been described above, but an arbitrary layer can be provided on the downstream side of the porous base material 3. For example, a porous plate having a rigidity higher than that of the porous base material 3 can be provided on the downstream side of the porous base material 3. A plurality of through-holes are formed in the porous plate in such a manner that the pressure loss of the gas passing through the through-holes is smaller than that of the porous base material 3. Thus, the gas separation membrane 1 can be supported without hindering the gas selectivity function of carbon dioxide in the gas separation membrane 1.
[0127] As the material constituting the porous plate, for example, a ceramic material, a metallic material, a polymeric material, or the like can be exemplified. Alternatively, the material constituting the porous plate can be a composite material of these materials and other materials.
[0128] 1.4. Characteristics of Gas Separation Membrane
[0129] Gas permeability R of carbon dioxide of the gas separation membrane 1 CO2 Preferably, 5000 x 10 -6 cm 3 (STP) / cm 2• sec•cmHg or more (5000 GPU or more), and more preferably 10000 GPU or more. Thereby, a gas separation membrane 1 having a high separation efficiency of carbon dioxide can be obtained. In addition, a gas separation membrane 1 that can reduce the amount of energy required for separation, specifically, can reduce the pressure difference between the upstream side and the downstream side of the gas separation membrane 1 can be realized. Note that the gas permeation degree R CO2 is measured by the method described later.
[0130] The gas permeation degree of nitrogen gas of the gas separation membrane 1 is set to R N2 At this time, the gas selectivity R CO2 N2 is preferably 2 or more, and more preferably 5 or more. When the gas selectivity R CO2 N2 When it is within the range, the gas separation membrane 1 can efficiently separate and recover carbon dioxide in a mixed gas. On the other hand, the upper limit value of the gas selectivity R CO2 N2 may not be set, but from the viewpoint of improving the ease of manufacturing the gas separation membrane 1, it is preferably 40 or less.
[0131] 2. Method for manufacturing gas separation membrane
[0132] Next, a method for manufacturing a gas separation membrane according to the embodiment will be described. Note that in the following description, a method for manufacturing the gas separation membrane 1 shown in FIG. 1 will be described as an example. Figure 1
[0133] Figure 6 is a process diagram showing the configuration of the method for manufacturing a gas separation membrane according to the embodiment.
[0134] Figure 6 The method for manufacturing a gas separation membrane shown in FIG. 10 has a coating film forming process S102 and an energy imparting process S104. With such a manufacturing method, the gas separation membrane 1 can be efficiently manufactured. Hereinafter, each process will be described.
[0135] 2.1. Coating film forming process
[0136] In the coating film forming process S102, first, a porous substrate 3 having a first porous layer 31 and a second porous layer 32 laminated with each other is prepared. The porous substrate 3 may, for example, be a porous sheet body in which the average pore diameter and the opening ratio and the like vary in the thickness direction, or a material in which two sheet bodies different from each other in the average pore diameter and the opening ratio and the like are joined. In the joining of the sheet bodies to each other, for example, an adhesive method using an adhesive, a direct joining method, or the like can be used.
[0137] In addition, it can also be a member obtained by performing a treatment to reduce the average pore diameter and the opening ratio on the upper surface side of the porous sheet member, or a treatment to increase the average pore diameter and the opening ratio on the lower surface side of the porous sheet member. As the film formation treatment, for example, in the case where the material constituting the sheet member is metal, an anodization method or the like can be exemplified. As the etching treatment, for example, a wet etching method or the like can be exemplified.
[0138] The prepared porous base material 3 is subjected to a cleaning treatment as needed. As the cleaning treatment, for example, a plasma treatment, a corona treatment, an ozone treatment, an ultraviolet irradiation treatment, or the like can be exemplified.
[0139] Next, a raw material liquid containing a raw material is supplied in contact with the first porous layer 31, and a coated film is obtained. The raw material liquid contains a monomer (prepolymer) and a solvent, or the like. The raw material liquid is applied on the upper surface 310 of the first porous layer 31 by various application methods. As the application method, for example, a dipping method, a dropping method, an inkjet method, a dispenser method, a spray method, a screen printing method, a coater application method, a spin coating method, or the like can be exemplified. After the coated film is formed, the coated film is dried as needed.
[0140] Note that the raw material liquid can not penetrate into the pores 312 of the first porous layer 31, but it is preferable to penetrate. Thereby, the coated film is in close contact with the first porous layer 31, and the coverage of the coated film is further improved. As a result, a separation layer 2 with a high coverage is finally obtained.
[0141] 2.2. Energy-imparting step
[0142] In the energy-imparting step S104, energy is imparted to the obtained coated film. As the method of imparting energy, for example, a method of irradiating an energy ray such as infrared rays, visible light, or ultraviolet rays, a method of irradiating plasma, a method of irradiating an electron beam, or the like can be exemplified. Thereby, the monomer is polymerized, and the coated film is hardened or cured. Thereby, a separation layer 2 can be obtained.
[0143] Note that it can also be that, in the energy-imparting step S104, the imparted energy is adjusted so that a part of the surface (a surface away from the porous base material 3) of the obtained coated film is hardened or cured, and on the other hand, a part of the back surface is in an unhardened or uncured state. In this case, the unhardened or uncured coated film is removed by the cleaning liquid. Thereby, the penetration depth of the separation layer 2 with respect to the pores 312 of the first porous layer 31 can be adjusted. As a result, the tightness of the separation layer 2 with respect to the first porous layer 31 can be improved, and the reduction in the gas permeation degree in the porous base material 3 can be suppressed.
[0144] 3. Use of gas separation membrane
[0145] The gas separation membrane 1 according to the embodiment can be used for separating and recovering carbon dioxide from a mixed gas containing carbon dioxide, separating and purifying carbon dioxide, and the like. In particular, it is effective to use the gas separation membrane 1 in a technology for separating and recovering carbon dioxide contained in the atmosphere (direct air capture (DAC)).
[0146] 4. Gas separation apparatus
[0147] Next, the gas separation apparatus according to the embodiment will be described.
[0148] Figure 7 is a cross-sectional view showing a schematic configuration of a gas separation apparatus 5 according to the embodiment.
[0149] Figure 7 The gas separation apparatus 5 shown is provided with a gas separation membrane 1, a fixing portion 52, a pipe 53, and an exhaust portion 54.
[0150] The fixing portion 52 fixes the gas separation membrane 1. In addition, the fixing portion 52 has a porous plate 51 that supports the gas separation membrane 1. A plurality of through-holes are formed in the porous plate 51. In addition, an internal space 522 on the side of the porous base material 3 of the gas separation membrane 1 is formed in the fixing portion 52.
[0151] The exhaust portion 54 exhausts the gas in the internal space 522 via the pipe 53. Thereby, the pressure of the internal space 522 is reduced to become a negative pressure with respect to an external space 524 on the side of the separation layer 2 of the gas separation membrane 1.
[0152] According to such a configuration, it is possible to make the mixed gas G1 supplied to the external space 524 permeate the gas separation membrane 1 and recover the permeated gas G2. The mixed gas G1 is a mixed gas containing carbon dioxide and other gas components. In the permeated gas G2, the carbon dioxide concentration is increased compared to the mixed gas G1. Thereby, it is possible to separate and recover carbon dioxide from the mixed gas G1.
[0153] In addition, the gas separation membrane 1 has a high gas selectivity and a high gas permeation degree with respect to carbon dioxide, and has a sufficient mechanical strength. Therefore, it is possible to realize the gas separation apparatus 5 having excellent separation performance of carbon dioxide.
[0154] 5. Effects of the Embodiment
[0155] The gas separation membrane 1 according to the embodiment is a gas separation membrane that allows carbon dioxide to permeate and separate from a mixed gas containing carbon dioxide, and includes a separation layer 2 and a porous substrate 3. The separation layer 2 is composed of a high molecular material and has a function of selectively and separating carbon dioxide. The porous substrate 3 has a first porous layer 31 that is in contact with the separation layer 2, and a second porous layer 32 that is provided on the side of the first porous layer 31 opposite to the separation layer 2.
[0156] In addition, the first porous layer 31 has a layer thickness T1, an average pore diameter d1, an opening ratio A1, and a maximum height roughness R1 of the upper surface 310 (a surface facing the separation layer 2). At this time, the layer thickness T1 is 0.1 μm or more and 10.0 μm or less, the average pore diameter d1 is 10 nm or more and 10,000 nm or less, the opening ratio A1 is 40% or more and 80% or less, and the maximum height roughness R1 is 1 nm or more and 200 nm or less.
[0157] In addition, the second porous layer 32 has a layer thickness T2, an average pore diameter d2, and an opening ratio A2. At this time, the layer thickness T2 is 10 μm or more and 1,000 μm or less, the ratio d2 / d1 of the average pore diameter d2 to the average pore diameter d1 is 1.1 or more and 10,000 or less, and the ratio A2 / A1 of the opening ratio A2 to the opening ratio A1 is 1.1 or more and 2.0 or less.
[0158] According to such a structure, it is possible to obtain a gas separation membrane 1 that has a high gas selectivity and a high gas permeation degree for carbon dioxide and has sufficient mechanical strength.
[0159] In the gas separation membrane 1 according to the embodiment, the ratio T2 / T1 of the layer thickness T2 to the layer thickness T1 is preferably 1 or more and 10,000 or less.
[0160] According to such a structure, it is possible to balance the function of supporting the separation layer 2 possessed by the first porous layer 31 and the function of gas permeability possessed by the second porous layer 32. Thus, it is possible to realize a porous substrate 3 that can sufficiently support even a thin separation layer 2 and has a sufficiently high gas permeation degree. As a result, it is possible to realize a gas separation membrane 1 that balances a high gas selectivity and a high gas permeation degree.
[0161] In the gas separation membrane 1 according to the embodiment, the separation layer 2 can contain an organopolysiloxane. In addition, the layer thickness T0 of the separation layer 2 is preferably 1 nm or more and 1,000 nm or less.
[0162] According to such a structure, the separation layer 2 exhibiting a high gas selectivity ratio with respect to carbon dioxide can be obtained. In addition, if the layer thickness TO of the separation layer 2 is within the range, the separation layer 2 having a good gas selectivity ratio with respect to carbon dioxide and a gas permeation degree can be obtained.
[0163] In the gas separation membrane 1 according to the embodiment, the porous base material 3 can also have the porous sheet 30 and the particles 4. The porous sheet 30 has an upper surface 301 (one face) and a lower surface 302 (another face) having a front and back relationship with each other. In addition, the through-hole 33 penetrating from the upper surface 301 to the lower surface 302 is formed in the porous sheet 30. Further, the particles 4 are inserted into the through-hole 33.
[0164] According to such a structure, the opening ratio of the porous sheet 30 can be easily adjusted. In addition, even in the case where the single structure of the porous sheet 30 is used, the first porous layer 31 and the second porous layer 32 can be formed, so that the manufacturing easiness and the cost reduction of the gas separation membrane 1 can be sought.
[0165] The manufacturing method of the gas separation membrane according to the embodiment has a coated film forming step S102 and an energy imparting step S104. In the coated film forming step S102, the porous base material 3 having the first porous layer 31 and the second porous layer 32 laminated with each other is prepared, and the raw material liquid is supplied in contact with the first porous layer 31, thereby obtaining a coated film. In the energy imparting step S104, the coated film is subjected to a treatment of imparting energy, thereby obtaining the separation layer 2 composed of a high molecular material, having a function of selectively and separating carbon dioxide.
[0166] The layer thickness of the first porous layer 31 is set to T1, the average pore diameter is set to d1, the opening ratio is set to A1, and the maximum height roughness of the upper surface 310 (the surface facing the separation layer 2) is set to R1. At this time, the layer thickness T1 is 0.1 μm or more and 10.0 μm or less, the average pore diameter d1 is 10 nm or more and 10000 nm or less, the opening ratio A1 is 40% or more and 80% or less, and the maximum height roughness R1 is 1 nm or more and 200 nm or less.
[0167] In addition, the layer thickness of the second porous layer 32 is set to T2, the average pore diameter is set to d2, and the opening ratio is set to A2. At this time, the layer thickness T2 is 10 μm or more and 1000 μm or less, the ratio d2 / d1 of the average pore diameter d2 to the average pore diameter d1 is 1.1 or more and 10000 or less, and the ratio A2 / A1 of the opening ratio A2 to the opening ratio A1 is 1.1 or more and 2.0 or less.
[0168] According to such a structure, a gas separation membrane 1 having a high gas selectivity ratio for carbon dioxide and a high gas permeation rate, and having sufficient mechanical strength, can be efficiently produced.
[0169] The gas separation device 5 according to the embodiment includes the gas separation membrane 1 according to the embodiment, a fixing portion 52, and an exhaust portion 54. The fixing portion 52 fixes the gas separation membrane 1. In addition, an internal space 522 is formed on the porous substrate 3 side of the gas separation membrane 1 of the fixing portion 52. The exhaust portion 54 depressurizes the internal space 522 in a manner that an external space 524 on the separation layer 2 side of the gas separation membrane 1 becomes a negative pressure.
[0170] According to such a structure, a gas separation device 5 having excellent separation performance for carbon dioxide can be realized.
[0171] The gas separation membrane, the method for producing a gas separation membrane, and the gas separation device according to the present application have been described above based on the preferred embodiments, but the present application is not limited thereto.
[0172] For example, the gas separation membrane and the gas separation device according to the present application can replace each of the portions of the embodiments with a structure having the same function, or can add any structure to the embodiments.
[0173] In addition, the method for producing a gas separation membrane according to the present application can be a method in which any process for any purpose is added to the embodiments.
[0174] Example
[0175] Next, a specific example of the present application will be described.
[0176] 6. Production of a gas separation membrane
[0177] 6.1. Example 1
[0178] First, a porous substrate made of porous alumina was prepared. The porous substrate was a laminate of a first porous layer and a second porous layer that differed in layer thickness, average pore diameter, and opening ratio.
[0179] Next, a coating film was obtained by spin coating a raw material liquid in contact with the first porous layer. The raw material liquid was a liquid containing a prepolymer of polydimethylsiloxane.
[0180] Next, the surface of the coating film was irradiated with ultraviolet rays having a wavelength of 365 nm for 1 hour. Thus, the coating film was hardened, and a gas separation membrane having a separation layer and a porous substrate was obtained.
[0181] Note that the structure of the produced gas separation membrane is shown in Table 1 ( Figure 8) shown in Table 1 (Examples 2 to 9 and Comparative Examples 1 to 9)
[0182] 6.2. Examples 2 to 9 and Comparative Examples 1 to 9
[0183] The gas separation membranes were obtained in the same manner as in Example 1, except that the structure of the gas separation membrane was changed as shown in Table 1 (Examples 2 to 9 and Comparative Examples 1 to 9). Figure 8 ) or Table 2 (Comparative Examples 1 to 9). Figure 9 The gas separation membranes were obtained in the same manner as in Example 1, except that the structure of the gas separation membrane was changed as shown in Table 1 (Examples 2 to 9 and Comparative Examples 1 to 9).
[0184] Figure 8 Table 1 is a table showing the structure of the gas separation membranes of each of the examples and the evaluation results of the gas separation membranes. Figure 9 Table 2 is a table showing the structure of the gas separation membranes of each of the comparative examples and the evaluation results of the gas separation membranes.
[0185] Note that the abbreviations of the constituent materials shown in Table 1 and Table 2 correspond to the following materials.
[0186] PDMS: polydimethylsiloxane
[0187] Al203: porous alumina membrane filter
[0188] Al203+ SiP: filter in which silicone particles are filled in the pores of the porous alumina membrane filter
[0189] MF1: cellulose mixed ester (mixture of cellulose acetate and cellulose nitrate) membrane filter
[0190] MF2: regenerated cellulose membrane filter
[0191] MF3: polycarbonate membrane filter
[0192] 7. Evaluation of gas separation membranes
[0193] For each of the gas separation membranes of the examples and the comparative examples, the following evaluations were performed.
[0194] 7.1. Separation layer coverage
[0195] For each of the gas separation membranes of the examples and the comparative examples, cross-section processing based on focused ion beam processing or the like was performed. Subsequently, the obtained cross-section was observed with a scanning transmission electron microscope (STEM).
[0196] Subsequently, based on the contrast of the observation image, the ratio of the length of the site where the separation layer was missing to the length of the interface between the porous substrate and the separation layer was calculated. Then, the ratio was taken as the area ratio X of the missing portion, and the coverage C of the separation layer was calculated by the following equation.
[0197] C [%] = 100 [%] - X [%]
[0198] The results of the calculation are shown in Table 1 and Table 2.
[0199] 7.2. CO2 gas permeance
[0200] Each of the gas separation membranes of the examples and the comparative examples was cut into a circular shape having a diameter of 5 cm to produce a test sample. Subsequently, using a gas permeability measuring device, a mixed gas of carbon dioxide : nitrogen at a volume ratio of 5 : 95 was supplied to the upstream side of the test sample. At this time, the total pressure of the upstream side was adjusted to 1.2 atm, the flow rate of the mixed gas was adjusted to 500 mL / min, and the temperature was adjusted to 40°C. The measurement of the gas permeance was performed in accordance with the gas permeance test method (Part 1: pressure difference method) prescribed in JIS K 7126-1:2006. The gas permeability measuring device used was GTR-11A / 31A manufactured by GTR Tech Co., Ltd. In the device, the gas after permeating the test sample was introduced into a gas chromatograph, and the gas permeance of each component was measured.
[0201] Subsequently, the CO2 gas permeance in each of the gas separation membranes was calculated from the analysis results. The results of the calculation are shown in Table 1 and Table 2.
[0202] 7.3. CO2 / N2 gas selectivity ratio
[0203] The N2 gas permeance in the gas separation membranes was calculated from the analysis results described above. Then, the ratio of the CO2 gas permeance to the N2 gas permeance was calculated as the CO2 / N2 gas selectivity ratio. The results of the calculation are shown in Table 1 and Table 2.
[0204] 7.4. Durability based on pressure difference
[0205] Each of the gas separation membranes of the examples and the comparative examples was set in a gas permeability measuring device so that the pressure difference (pressure difference) between the upstream side and the downstream side was 0.1 MPa, and the downstream side was depressurized. Then, the state was maintained for 1 week.
[0206] After 1 week, the gas separation membrane was taken out, and it was confirmed by magnified observation whether or not there was a breakage. Then, the observation results were evaluated in accordance with the following evaluation criteria. The results of the evaluation are shown in Table 1 and Table 2.
[0207] A: No breakage was confirmed on the gas separation membrane
[0208] C: Breakage was confirmed on the gas separation membrane
[0209] As is clear from Table 1 and Table 2, it was confirmed that the gas separation membranes of the examples had a high gas selectivity ratio and a high gas permeance with respect to carbon dioxide, and were excellent in mechanical strength.
Claims
1. A gas separation membrane, characterized in that, The gas separation membrane allows carbon dioxide to pass through and be separated from a mixture of gases containing carbon dioxide, and the gas separation membrane comprises: A separation layer, comprising a polymer material, having the function of selectively separating carbon dioxide; and A porous substrate having a first porous layer in contact with the separation layer and a second porous layer disposed on the side of the first porous layer opposite to the separation layer. When the thickness of the first porous layer is set to T1, the average pore size to d1, the aperture ratio to A1, and the maximum height roughness of the surface facing the separation layer is set to R1... The layer thickness T1 is greater than 0.1 μm and less than 10.0 μm. The average aperture d1 is greater than 10 nm and less than 10,000 nm. The aperture ratio A1 is above 40% and below 80%. The maximum height roughness R1 is greater than 1 nm and less than 200 nm. When the thickness of the second porous layer is set to T2, the average pore size to d2, and the aperture ratio to A2, The layer thickness T2 is greater than 10 μm and less than 1000 μm. The ratio of the average aperture d2 to the average aperture d1, d2 / d1, is greater than or equal to 1.1 and less than or equal to 10,000. The ratio of the aperture ratio A2 to the aperture ratio A1, A2 / A1, is 1.1 or more and 2.0 or less.
2. The gas separation membrane according to claim 1, wherein, The ratio of the layer thickness T2 to the layer thickness T1, T2 / T1, is greater than 1 and less than 10000.
3. The gas separation membrane according to claim 1 or 2, wherein, The separation layer contains an organopolysiloxane. The thickness of the separation layer is greater than 1 nm and less than 1000 nm.
4. The gas separation membrane according to claim 1 or 2, wherein, The porous substrate has the following characteristics: A porous sheet having one face and another face that are mutually internal and external, and having through pores extending from the one face to the other face; and The particles are inserted into the through-hole.
5. A method for manufacturing a gas separation membrane, characterized in that, have: The process of obtaining the coated film is as follows: a porous substrate having a first porous layer and a second porous layer stacked on each other is prepared, and a raw material liquid is supplied in a manner that contacts the first porous layer, thereby obtaining a coated film. as well as The process of obtaining the separation layer involves subjecting the coated membrane to energy to obtain a separation layer composed of polymer materials that selectively separates carbon dioxide. When the thickness of the first porous layer is set to T1, the average pore size to d1, the aperture ratio to A1, and the maximum height roughness of the surface facing the separation layer is set to R1... The layer thickness T1 is greater than 0.1 μm and less than 10.0 μm. The average aperture d1 is greater than 10 nm and less than 10,000 nm. The aperture ratio A1 is above 40% and below 80%. The maximum height roughness R1 is greater than 1 nm and less than 200 nm. When the thickness of the second porous layer is set to T2, the average pore size to d2, and the aperture ratio to A2, The layer thickness T2 is greater than 10 μm and less than 1000 μm. The ratio of the average aperture d2 to the average aperture d1, d2 / d1, is greater than or equal to 1.1 and less than or equal to 10,000. The ratio of the aperture ratio A2 to the aperture ratio A1, A2 / A1, is 1.1 or more and 2.0 or less.
6. A gas separation device, characterized in that, have: The gas separation membrane according to claim 1 or 2; A fixing portion, wherein the gas separation membrane is fixed and an internal space is formed on the porous substrate side of the gas separation membrane; and The exhaust section depressurizes the internal space by creating a negative pressure in the external space relative to the separation layer side of the gas separation membrane.
Citation Information
Patent Citations
Gas separation membrane and production method of gas separation membrane
JP2024042578A