Carbon film composite and method for manufacturing carbon film composite

Abstract

A carbon film composite has a porous support (11) and a carbon film (12) provided on the surface of the support (11). A carbon-rich layer (35) having a higher carbon content than the surrounding portion is provided inside the support (11). The carbon-rich layer (35) is disposed at a position separated from the surface of the support (11). Thus, the permeation flux of the carbon film composite (1) can be suppressed from decreasing and the separation factor can be improved.

Description

Technical Field

[0001] This invention relates to carbon film composites and their manufacturing methods.

[0002] [Reference to relevant applications]

[0003] This application claims priority based on Japanese Patent Application JP2024-052143, filed on March 27, 2024, the entire disclosure of which is incorporated herein by reference. Background Technology

[0004] Previously, carbon membrane composites, in which a carbon membrane is disposed on the surface of a porous support, have been used as filters with excellent chemical stability and heat resistance. In Japanese Patent Application Publication No. 2010-509035 (Document 1) and International Publication No. 2012 / 111792 (Document 2), techniques for improving the permeation flux and separation coefficient of carbon membrane composites have been proposed.

[0005] Reference 1 discloses a technique that increases the permeation flux of a carbon film composite by forming a composite layer with a thickness of less than 1 mm (i.e., a layer formed by the carbon film material penetrating into the dense layer of the support) at the interface between the support and the carbon film. Furthermore, as a method for manufacturing this carbon film composite, the following technique is disclosed: when applying a carbon film precursor solution to the surface of the support, pressure is applied to the pores of the support, making it difficult for the precursor solution to penetrate from the surface of the support into the pores, thereby reducing the thickness of the carbon film and the composite layer and making them more uniform.

[0006] Reference 2 proposes that a layer with a smaller pore size than the support be formed at the interface between the carbon film and the support in a carbon film composite, and that carbon be formed to cover the inner surface of the pores in both the layer and the support. According to Reference 2, fluids (i.e., gases, liquids, etc.) that have permeated through the carbon film move rapidly within the pores of the layer and the support and are discharged outside the system by means of the carbon. Therefore, the permeation flux and separation coefficient of the carbon film composite are improved.

[0007] However, in the carbon film composite in Reference 1, the reduction in pressure drop of the composite layer is limited, and the increase in permeation flux is also limited.

[0008] In the carbon film composite of Reference 2, carbon permeates into the entirety of the aforementioned layer and into the portion of the support near the layer. Therefore, the carbon, present over a large area within the pores, hinders fluid permeation, potentially reducing the permeation flux of the carbon film composite. Furthermore, the carbon content in the aforementioned layer, with its smaller particle size, is higher than that in the support. As a result, since the layer with a higher carbon content is in direct contact with the carbon film, fluid that has already permeated through the carbon film finds it difficult to permeate through this layer, potentially further reducing the permeation flux of the carbon film composite. Summary of the Invention

[0009] This invention relates to carbon membrane composites, with the aim of suppressing the decrease in permeation flux of carbon membrane composites and improving the separation coefficient.

[0010] Scheme 1 is a carbon film composite comprising a porous support and a carbon film disposed on the surface of the support. A carbon-rich layer is disposed inside the support, located separately from the surface of the support, and has a higher carbon content than the surrounding areas.

[0011] This can suppress the decrease in permeation flux of the carbon membrane complex and improve the separation coefficient.

[0012] The invention of Scheme 2 is based on the carbon film composite of Scheme 1, wherein the support comprises: a first layer extending from the surface of the support toward the interior of the support; and a second layer extending from the first layer toward the interior of the support, and having an average pore size larger than that of the first layer. The carbon-rich layer is located closer to the surface of the support than the interface between the first and second layers.

[0013] The invention of Scheme 3 is based on the carbon film composite of Scheme 2, wherein the carbon-rich layer is in contact with the interface between the first layer and the second layer.

[0014] The invention of Scheme 4 is based on the carbon film composite of Scheme 2 (or Scheme 2 or Scheme 3), wherein, in the thickness direction perpendicular to the surface of the support, the sum of the thickness of the carbon-rich layer from the surface of the support to the thickness of the carbon-rich layer is more than 0.1 μm and less than 30 μm.

[0015] The invention of Scheme 5 is based on the carbon film composite of Scheme 2 (or any of Schemes 2 to 4), wherein, in the thickness direction perpendicular to the surface of the support, the thickness from the surface of the support to the carbon-rich layer is more than 1.0 times and less than 20.0 times the thickness of the carbon-rich layer.

[0016] The invention of Scheme 6, based on the carbon film composite of Scheme 1, comprises: a first layer extending from the surface of the support toward the interior of the support; and a second layer extending from the first layer toward the interior of the support, wherein the second layer has an average pore size larger than that of the first layer. The carbon-rich layer is located on the opposite side of the surface of the support relative to the interface between the first layer and the second layer.

[0017] The invention of Scheme 7 is based on the carbon film composite of Scheme 6, wherein in the thickness direction perpendicular to the surface of the support, the sum of the thickness of the carbon-rich layer from the surface of the support to the thickness of the carbon-rich layer is more than 1 μm and less than 1000 μm.

[0018] The invention of Scheme 8 is based on the carbon film composite of any of Schemes 1 to 7, wherein the maximum carbon content in the carbon-rich layer is more than 1.1 times and less than 4.0 times the average carbon content in the region between the surface of the support and the carbon-rich layer.

[0019] The invention of Scheme 9 is based on the carbon film composite of Scheme 8, wherein the maximum carbon content in the carbon-rich layer is more than 1.2 times and less than 2.0 times the average carbon content in the region between the surface of the support and the carbon-rich layer.

[0020] The invention of Scheme 10 is based on the carbon film composite of any of Schemes 1 to 7 (or any of Schemes 1 to 5), wherein the maximum carbon content in the carbon-rich layer is more than 0.05 times and less than 0.25 times the maximum carbon content in the carbon film.

[0021] The invention of Scheme 11 is based on the carbon film composite of any of Schemes 1 to 7 (or any of Schemes 1 to 6), wherein the thickness of the carbon-rich layer is 0.01 μm or more and 15 μm or less in the thickness direction perpendicular to the surface of the support.

[0022] The invention of Scheme 12 is a method for manufacturing a carbon film composite, comprising the following steps: a) applying a first precursor solution containing a first precursor from the surface side of a porous support and allowing it to penetrate, thereby forming a first precursor layer containing the first precursor inside the support; b) removing a portion of the first precursor layer from the surface side of the support; c) applying a second precursor solution containing a second precursor from the surface side of the support, thereby forming a second precursor layer containing the second precursor inside the support and forming a membrane containing the second precursor, i.e., a second precursor membrane, on the surface of the support; and d) forming a carbon film on the surface of the support by carbonizing the first precursor layer, the second precursor layer, and the second precursor membrane, while simultaneously forming a carbon-rich layer inside the support, the carbon-rich layer being disposed at a location separated from the surface of the support and having a higher carbon content than the surrounding area.

[0023] The invention of Scheme 13, based on the manufacturing method of carbon film composite of Scheme 12, further includes, between step b) and step c), a step of curing the first precursor layer remaining inside the support.

[0024] The invention of Scheme 14 is a method for manufacturing a carbon film composite, comprising the following steps: a) applying a first precursor solution containing a first precursor from the surface side of a porous support, while simultaneously depressurizing the side of the support opposite to the surface, causing the first precursor solution to penetrate into the support, thereby forming a first precursor layer containing the first precursor inside the support; b) applying a second precursor solution containing a second precursor from the surface side of the support, thereby forming a second precursor layer containing the second precursor inside the support, and forming a membrane containing the second precursor, i.e., a second precursor membrane, on the surface of the support; and c) forming a carbon film on the surface of the support by carbonizing the first precursor layer, the second precursor layer, and the second precursor membrane, while simultaneously forming a carbon-rich layer inside the support, the carbon-rich layer being disposed at a position separated from the surface of the support, and having a higher carbon content than the surrounding area.

[0025] The invention of Scheme 15, based on the method for manufacturing carbon film composite of Scheme 14, further includes, between step a) and step b), a step of curing the first precursor layer.

[0026] The above-mentioned objects, as well as other objects, features, solutions, and advantages, will become clear from the following detailed description of the invention with reference to the accompanying drawings. Attached Figure Description

[0027] Figure 1 This is a side view of the carbon film composite involved in the first embodiment.

[0028] Figure 2 This is a longitudinal cross-sectional view of the carbon film composite.

[0029] Figure 3 This is an enlarged cross-sectional view of a part of the carbon film composite.

[0030] Figure 4 This is an enlarged cross-sectional view of a part of the carbon film composite.

[0031] Figure 5 This is an enlarged cross-sectional view of a part of the carbon film composite.

[0032] Figure 6A It is a graph showing the relationship between measurement depth and carbon content.

[0033] Figure 6BIt is a graph showing the relationship between measurement depth and carbon content.

[0034] Figure 6C It is a graph showing the relationship between measurement depth and carbon content.

[0035] Figure 7A It is a graph showing the relationship between measurement depth and carbon content.

[0036] Figure 7B It is a graph showing the relationship between measurement depth and carbon content.

[0037] Figure 7C It is a graph showing the relationship between measurement depth and carbon content.

[0038] Figure 8A It is a graph showing the relationship between measurement depth and carbon content.

[0039] Figure 8B It is a graph showing the relationship between measurement depth and carbon content.

[0040] Figure 8C It is a graph showing the relationship between measurement depth and carbon content.

[0041] Figure 9A It is a graph showing the relationship between measurement depth and carbon content.

[0042] Figure 9B It is a graph showing the relationship between measurement depth and carbon content.

[0043] Figure 9C It is a graph showing the relationship between measurement depth and carbon content.

[0044] Figure 10 This is a diagram showing the manufacturing process of carbon film composites.

[0045] Figure 11A This is a cross-sectional view of the carbon film composite during the manufacturing process.

[0046] Figure 11B This is a cross-sectional view of the carbon film composite during the manufacturing process.

[0047] Figure 11C This is a cross-sectional view of the carbon film composite during the manufacturing process.

[0048] Figure 11D This is a cross-sectional view of the carbon film composite during the manufacturing process.

[0049] Figure 12 This is a cross-sectional view of the separation device.

[0050] Figure 13 This is an enlarged cross-sectional view of a portion of the carbon film composite involved in the second embodiment.

[0051] Figure 14 This is a diagram showing the manufacturing process of carbon film composites.

[0052] Figure 15A This is a cross-sectional view of the carbon film composite during the manufacturing process.

[0053] Figure 15B This is a cross-sectional view of the carbon film composite during the manufacturing process.

[0054] Figure 15C This is a cross-sectional view of the carbon film composite during the manufacturing process.

[0055] Figure 16 This is an enlarged cross-sectional view of a part of other carbon film composites. Detailed Implementation

[0056] Figure 1 This is a side view showing the end face of the carbon film composite 1 according to the first embodiment of the present invention. Figure 2 This is a longitudinal cross-sectional view of carbon film composite 1. Carbon film composite 1 is along... Figure 2 A roughly columnar component extending in the left-right direction. In the following description, it will also be... Figure 2 The left and right directions in the middle are called the "length directions". Figure 1 The image shows one end face of the carbon film composite 1 along its length, and the other end face is also the same as... Figure 1 The shape shown is the same as the shape shown.

[0057] The carbon film composite 1 comprises a support 11 and a carbon film 12. The support 11 is a porous component that allows gas and liquid to pass through. Figure 1 and Figure 2 The illustrated support 11 has an integral structure in which a plurality of through holes 111 (hereinafter also referred to as "compartments 111") extending along the length direction of the integrally formed, interconnected cylindrical body are provided. The integral structure includes the concept of a honeycomb structure. The support 11 is, for example, generally cylindrical. The plurality of compartments 111 are, for example, arranged in a generally concentric circle in the cross-section of the support 11 perpendicular to the length direction. The cross-sectional shape of each compartment 111 perpendicular to the length direction is, for example, generally circular. It should be noted that "generally circular" includes not only perfect circles, but also ellipses and deformed circles. Figure 2 In this example, the diameter of compartment 111 is drawn larger than the actual diameter, and the number of compartments 111 is drawn smaller than the actual number. It should be noted that the number, cross-sectional shape, and arrangement of compartments 111 are not limited to the example above and various changes can be made.

[0058] The length of the support 11 (i.e., Figure 2The length (in the left-right direction) is, for example, 10cm to 200cm. The outer diameter of the support body 11 is, for example, 0.5cm to 30cm. The distance between the central axes of adjacent compartments 111 is, for example, 0.3mm to 10mm. The inner diameter of the compartment 111 is, for example, 0.5mm to 25mm. It should be noted that the shape of the support body 11 can also be, for example, honeycomb, flat, tubular, cylindrical, prismatic, or polygonal. When the shape of the support body 11 is tubular or cylindrical, the thickness of the support body 11 is, for example, 0.1mm to 10mm.

[0059] A carbon film 12 is provided on the inner surface of each compartment 111. Preferably, the carbon film 12 is provided in a manner that covers approximately the entire inner surface of each compartment 111. A support 11 is used to support the carbon film 12. Figure 1 and Figure 2 In the middle, the carbon film 12 is drawn with thick lines.

[0060] Figure 3 yes Figure 2 An enlarged cross-sectional view of a portion of the carbon film composite 1 shown. Figure 3 In the drawing, parallel oblique lines are used to mark the carbon film 12, and the thickness of the carbon film 12 is drawn to be thicker than it actually is. Additionally, the diameter of compartment 111 is drawn to be smaller than it actually is. Figure 3 In the diagram, the particles constituting the support 11 are schematically drawn in circles, but the particles can have various shapes.

[0061] exist Figure 3 In the example shown, the support 11 includes a substrate 31, an intermediate layer 32, and a surface layer 33. The substrate 31, intermediate layer 32, and surface layer 33 are all porous components. The substrate 31 has the integral structure described above. In the support 11, a compartment 111 is formed by providing the intermediate layer 32 and the surface layer 33 on the inner surface of each through-hole (i.e., through-hole intended to become a compartment 111) in the substrate 31. The intermediate layer 32 is in direct contact with the inner surface of each through-hole in the substrate 31 and is provided in a manner that covers the entire inner surface. The intermediate layer 32 is a generally cylindrical portion with a relatively thin radial thickness (hereinafter also simply referred to as "radial") centered on the central axis of the compartment 111.

[0062] The surface layer 33 is in direct contact with the inner surface of the intermediate layer 32 and is disposed in such a way that it covers the entire inner surface. That is, the surface layer 33 is indirectly disposed on the substrate 31 through the intermediate layer 32. The surface layer 33 is a generally cylindrical portion with a relatively thin radial thickness. When viewed from the inside of the compartment 111, the surface layer 33 is the innermost portion of the support 11. That is, the inner surface of the surface layer 33 is the inner surface of the compartment 111. A carbon film 12 is disposed on the inner surface of the surface layer 33 in such a way that it covers the entire inner surface. The carbon film 12 is in direct contact with the inner surface 331 of the surface layer 33. That is, the inner surface of the surface layer 33 is the surface of the support 11 on which the carbon film 12 is formed.

[0063] The portion near the inner side of compartment 111 has a laminated structure consisting of a surface layer 33, an intermediate layer 32, and a substrate 31 stacked along the thickness direction (i.e., radially about the central axis of compartment 111). In this laminated structure, the surface layer 33 is a first layer extending from the surface of support 11 toward the interior of support 11 (i.e., radially outward from the inner side of compartment 111). The intermediate layer 32 is a second layer extending from the surface layer 33 toward the interior of support 11 and is disposed between the surface layer 33 and the substrate 31. The substrate 31 is a third layer extending from the intermediate layer 32 toward the interior of support 11.

[0064] The thickness of the surface layer 33 in the thickness direction (i.e., the direction perpendicular to the surface of the support 11) is, for example, 1 μm or more and 100 μm or less. The thickness of the intermediate layer 32 in the thickness direction is, for example, 100 μm or more and 500 μm or less. The thickness of the surface layer 33 in the thickness direction (hereinafter also simply referred to as "thickness") can be determined, for example, by observing the polished cross-section of the sample using a scanning electron microscope (SEM). Similarly, the thickness of the intermediate layer 32 can also be determined, for example, by observing the polished cross-section of the sample using an SEM.

[0065] In this embodiment, the material of the support 11 (i.e., the substrate 31, the intermediate layer 32, and the surface layer 33) is a ceramic that has chemical stability during the process of forming the carbon film 12. The support 11 is formed, for example, from a sintered ceramic body. Examples of ceramic sintered bodies selected as materials for the support 11 include alumina, silicon dioxide, mullite, zirconium oxide, titanium dioxide, yttrium oxide, silicon nitride, and silicon carbide. Preferably, the support 11 is formed from alumina, mullite, zirconium oxide, or titanium dioxide. In this embodiment, alumina is used as the material for the support 11, considering its high corrosion resistance, small change in pore size due to temperature variations, and high strength. It should be noted that the materials of the substrate 31, the intermediate layer 32, and the surface layer 33 can be the same or different.

[0066] The support 11 (i.e., the substrate 31, the intermediate layer 32, and the surface layer 33) includes, for example, an inorganic binder material for binding the aggregate particles of the ceramic sintered body. At least one of titanium dioxide, mullite, easily sinterable alumina, silica, glass frit, clay minerals, and easily sinterable cordierite can be used as the inorganic binder material.

[0067] In addition, the support 11 may also contain alkali metals and / or alkaline earth metals. Examples of such alkali metals and alkaline earth metals include sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg).

[0068] The average pore size of the surface layer 33 is smaller than that of the intermediate layer 32 and the substrate 31. The average pore size of the intermediate layer 32 is smaller than that of the substrate 31. In other words, the average pore size of the substrate 31 is larger than that of the intermediate layer 32, and the average pore size of the intermediate layer 32 is larger than that of the surface layer 33. The average pore size of the substrate 31 is, for example, 0.01 μm or more and 70 μm or less, preferably 0.05 μm or more and 25 μm or less. The average pore size of the intermediate layer 32 is, for example, 0.01 μm or more and 10 μm or less. The average pore size of the surface layer 33 is, for example, 0.005 μm or more and 2.0 μm or less, preferably 0.05 μm or more and 0.5 μm or less. The average pore sizes of the substrate 31, intermediate layer 32, and surface layer 33 can be measured, for example, using a mercury porosimeter, a pore size distribution measuring instrument, or a nanoscale pore size distribution measuring instrument.

[0069] The porosity of the surface layer 33, intermediate layer 32, and substrate 31 is, for example, approximately the same. It should be noted that the porosity of the surface layer 33, intermediate layer 32, and substrate 31 may also be different. The porosity near the surface of the carbon film 12 to be formed on the support 11 is, for example, 20% or more and 60% or less. The porosity can be obtained as the area ratio of the space present in the SEM image of the cross-section of the support 11.

[0070] The average particle size of the aggregate particles in surface layer 33 (i.e., the median particle size (D) in the volumetric particle size distribution) 50 The average particle size of the aggregate particles in the intermediate layer 32 is smaller than that in the substrate 31. Furthermore, the average particle size of the aggregate particles in the intermediate layer 32 is smaller than that in the substrate 31. The average particle size of the aggregate particles in the substrate 31 is, for example, 5 μm to 200 μm. The average particle size of the aggregate particles in the substrate 31, intermediate layer 32, and surface layer 33 can be measured, for example, by laser diffraction.

[0071] As described above, the carbon membrane 12 is formed on the inner surface of each compartment 111 (i.e., on the inner surface of the surface layer 33) and covers approximately the entire inner surface. In this embodiment, the carbon membrane 12 is generally cylindrical about a central axis extending along the length of the compartment 111. The carbon membrane 12 is a porous membrane with micropores formed approximately entirely of carbon or carbides. The carbon membrane 12 separates specific substances from a mixture of multiple substances through a molecular sieve effect. For example, when a mixture of water and ethanol is introduced into the compartment 111 of the carbon membrane composite 1, water is selectively separated from the mixture by the carbon membrane 12, permeates through the support 11, and is discharged from the outer surface of the carbon membrane composite 1.

[0072] The average pore size of the carbon film 12 is smaller than the average pore size of the surface layer 33 of the support 11. The average pore size of the carbon film 12 is, for example, 0.2 nm or more and 1.0 nm or less. By making the average pore size of the carbon film 12 0.2 nm or more, the decrease in the permeation flux of the substance to be separated can be suppressed. Furthermore, by making the average pore size of the carbon film 12 1.0 nm or less, the decrease in the separation coefficient (i.e., selectivity) of the carbon film 12 can be suppressed. The average pore size of the carbon film 12 can be measured, for example, by a gas permeation method.

[0073] The thickness of the carbon film 12 (i.e., the thickness in the aforementioned thickness direction) is, for example, 0.1 μm or more and 5.0 μm or less, preferably 0.2 μm or less and 2.5 μm or less, and more preferably 0.3 μm or more and 1.5 μm or less. When the carbon film 12 is thickened, the separation coefficient increases. When the carbon film 12 is thinned, the permeation flux increases.

[0074] Figure 4 yes Figure 3 A magnified cross-sectional view of the area near carbon film 12. (See image below.) Figure 4 As indicated by the parallel diagonal line different from the carbon film 12, a carbon-rich layer 35 is disposed inside the support 11. The carbon-rich layer 35 is a layered region with a higher carbon content than the surrounding region of the carbon-rich layer 35 in the support 11.

[0075] The carbon-rich layer 35 is disposed inside the support 11 at a position radially outward from the inner side 331 of the surface layer 33 (i.e., the surface of the support 11). The carbon-rich layer 35 extends substantially parallel to the inner side 331 of the surface layer 33 (i.e., the inner side of the compartment 111). The thickness of the carbon-rich layer 35 in the aforementioned thickness direction (i.e., the direction perpendicular to the surface of the support 11) is substantially constant around the circumference of the compartment 111. The carbon-rich layer 35 is a substantially cylindrical portion with the central axis of the compartment 111 as its approximate center.

[0076] exist Figure 4In the example shown, the carbon-rich layer 35 is substantially entirely disposed inside the surface layer 33. In other words, the carbon-rich layer 35 is substantially entirely located between the interface 332 of the surface layer 33 and the intermediate layer 32 and the inner surface 331 of the surface layer 33. Further, the carbon-rich layer 35 is located closer to the inner surface 331 of the surface layer 33 than the interface 332 between the surface layer 33 and the intermediate layer 32 (i.e., the radially inner side, closer to the inner surface 331 in the aforementioned thickness direction). Additionally, the substantially cylindrical interface 352 of the carbon-rich layer 35 on the side furthest from the inner surface 331 of the surface layer 33 (i.e., the radially outer side) is located on the interface 332 of the surface layer 33 and the intermediate layer 32. In other words, the carbon-rich layer 35 is in contact with the interface 332 of the surface layer 33 and the intermediate layer 32.

[0077] The portion of the support 11 closer to the inner surface 331 of the surface layer 33 than the carbon-rich layer 35 (i.e., radially inner side) is a portion with a lower carbon content than the carbon-rich layer 35, hereinafter referred to as the "low-carbon layer 36". The low-carbon layer 36 is the region between the inner surface 331 of the surface layer 33 (i.e., the surface of the support 11) and the carbon-rich layer 35. The low-carbon layer 36 is disposed adjacent to and in direct contact with the carbon film 12 and the carbon-rich layer 35 between the carbon film 12 and the carbon-rich layer 35. The generally cylindrical interface 351 of the carbon-rich layer 35, closer to the inner surface 331 of the surface layer 33 (i.e., radially inner side), is the interface between the carbon-rich layer 35 and the low-carbon layer 36.

[0078] It should be explained that, for example Figure 5 As shown, the carbon-rich layer 35 can also be configured such that it is separated radially inward from the interface 332 between the surface layer 33 and the intermediate layer 32 within the surface layer 33. In this case, the radially outer interface 352 of the carbon-rich layer 35 is located radially inward and separated from the interface 332 between the surface layer 33 and the intermediate layer 32. In other words, the radially outer interface 352 of the carbon-rich layer 35 is located between the interface 351 between the low-carbon layer 36 and the carbon-rich layer 35 and the interface 332 between the surface layer 33 and the intermediate layer 32. In this case, the carbon content in the surface layer 33 from the radially outer interface 352 of the carbon-rich layer 35 to the interface 332 between the surface layer 33 and the intermediate layer 32 is less than the carbon content of the carbon-rich layer 35.

[0079] The thickness of the carbon-rich layer 35 is, for example, 0.01 μm or more and 15 μm or less, preferably 0.01 μm or more and 10 μm or less. The thickness of the low-carbon layer 36 is, for example, 1.0 times or more and 20.0 times or less of the thickness of the carbon-rich layer 35, preferably 1.5 times or more and 15 times or less. The sum of the thickness of the low-carbon layer 36 and the thickness of the carbon-rich layer 35 (i.e., the sum of the thickness from the inner surface 331 of the surface layer 33 to the carbon-rich layer 35 and the thickness of the carbon-rich layer 35) is, for example, 0.1 μm or more and 30 μm or less, preferably 5 μm or more and 25 μm or less.

[0080] The thicknesses of the carbon-rich layer 35 and the low-carbon layer 36 were determined as follows: First, the cross-section of the carbon film composite 1 was ground using an ion milling method. Then, elemental mapping analysis was performed on the cross-section using a field emission electron probe microanalysis (FE-EPMA) system.

[0081] Next, within the mapped field of view, the carbon mass concentration at multiple locations at the same distance (hereinafter also referred to as the "measurement depth") from the surface 121 of the carbon film 12 in the thickness direction is obtained, and the arithmetic mean of the obtained mass concentrations is taken as the carbon content at that measurement depth. In other words, the arithmetic mean of the carbon mass concentration at a measurement depth within the mapped field of view is taken as the carbon content at that measurement depth. The aforementioned carbon mass concentration refers to the value obtained by normalizing the signal intensity of the carbon characteristic X-rays using the signal intensity of a standard sample. Furthermore, the carbon content at each measurement depth within the mapped field of view is processed in the same way as described above, thereby obtaining the relationship between the measurement depth and the carbon content.

[0082] Figure 6A This is an example illustrating the relationship between the measurement depth and carbon content in the cross-section of the sample of carbon film composite 1. Figure 6A In the illustrated graph, the horizontal axis represents the measurement depth, and the vertical axis represents the carbon content. The measurement depth 0 corresponds to the surface 121 of the carbon film 12. Figure 6A The broken line 8 shown in solid form represents the relationship between measurement depth and carbon content. Figure 6A In order to facilitate understanding of the relationship between the measurement depth and the structure of the carbon film composite 1, a portion of the cross-section of the carbon film composite 1 is also shown at the bottom of the graph.

[0083] If the relationship between the measured depth and carbon content is obtained, the positions of the interfaces 351 and 352 of the carbon-rich layer 35 in the thickness direction can be determined based on this relationship in the following manner. First, Figure 6A In order to approximate the broken line 8 with multiple straight lines, multiple boundary lines 60 are set according to the approximate shape of the broken line 8, thereby dividing the horizontal axis into multiple regions. Each boundary line 60 is... Figure 6A A straight line extending vertically in the middle, represented by a dashed line. Figure 6AThe position of the boundary line 60 shown is only a provisional position, which is variable as described later. In the outline shape of the polyline 8, the boundary line 60 is temporarily set near a position where the slope changes significantly.

[0084] exist Figure 6A In the example shown, the horizontal axis is divided into 6 regions 61 to 66 by 5 boundary lines 60. Figure 6A In the diagram, arrows extending left and right indicate the ranges corresponding to regions 61-66. Regions 61-66 extend from... Figure 6A Arranged consecutively from left to right. Figure 6A In the example shown, regions 61 and 62 roughly correspond to carbon film 12, region 63 roughly corresponds to low carbon layer 36, regions 64 and 65 roughly correspond to carbon rich layer 35, and region 66 roughly corresponds to intermediate layer 32.

[0085] exist Figure 6A In the example shown, the carbon content in the carbon film 12 is approximately constant from the surface 121 of the carbon film 12 up to a predetermined measurement depth, and decreases with increasing measurement depth at the interface between the carbon film 12 and the support 11, i.e., near the inner surface 331 of the surface layer 33. It should be noted that, as will be described later, the carbon content in the carbon film 12 may sometimes increase with increasing measurement depth from the surface 121 of the carbon film 12 up to a predetermined measurement depth.

[0086] exist Figure 6A In the example shown, the carbon content in the low-carbon layer 36 decreases as the inner surface 331 of the surface layer 33 approaches the interface 351 of the low-carbon layer 36 and the carbon-rich layer 35. It should be noted that, as described later, the carbon content in the low-carbon layer 36 can sometimes be approximately constant. Additionally, the carbon content in the low-carbon layer 36 increases as the inner surface 331 of the surface layer 33 approaches the interface 351 of the low-carbon layer 36 and the carbon-rich layer 35.

[0087] exist Figure 6A In the example shown, the carbon content in the carbon-rich layer 35 increases radially outward from the interface 351 between the low-carbon layer 36 and the carbon-rich layer 35, and decreases as it approaches the interface 352 (i.e., the interface 332 between the surface layer 33 and the intermediate layer 32) on the radially outer side of the carbon-rich layer 35. It should be noted that, as will be described later, the carbon content in the carbon-rich layer 35 may also sometimes remain approximately constant at the center in the thickness direction of the carbon-rich layer 35.

[0088] exist Figure 6A In the example shown, the carbon content in the intermediate layer 32 is approximately constant regardless of the measurement depth. It should be noted, as will be discussed later, that the carbon content in the intermediate layer 32 can sometimes decrease with increasing measurement depth.

[0089] After temporarily setting the above multiple boundary lines to 60, as follows: Figure 6B As shown, the portions of broken line 8 corresponding to regions 61 to 66 are approximated by straight lines. Figure 6B In the diagram, double-dotted lines represent approximate straight lines 81 to 86 within regions 61 to 66. Subsequently, the coefficients of determination R for each approximate straight line 81 to 86 are obtained. 2 And these determination coefficients R 2 The sum (hereinafter also referred to as the "total determination coefficient") serves as an indicator of the appropriateness of the positions of the multiple boundary lines 60. The appropriateness of the positions of the multiple boundary lines 60 increases as the total determination coefficient increases.

[0090] Next, the positions of multiple boundary lines 60 are repeatedly changed, and the total determination coefficient is obtained. The position of the boundary line 60 with the largest total determination coefficient is determined as the appropriate position of the boundary line 60. Once the position of the boundary line 60 is determined, as follows... Figure 6C As shown, the intersection point 801 of the approximate straight line 83 in region 63 corresponding to the low-carbon layer 36 and the approximate straight line 84 in region 64 corresponding to the carbon-rich layer 35 is determined. Furthermore, the measurement depth corresponding to the intersection point 801 is determined as the distance in the thickness direction between the radially inner interface 351 of the carbon-rich layer 35 and the surface 121 of the carbon film 12. That is, the position of the interface 351 of the carbon-rich layer 35 in the thickness direction is determined from the measurement depth corresponding to the intersection point 801. Additionally, the intersection point 802 of the approximate straight line 85 in region 65 corresponding to the carbon-rich layer 35 and the approximate straight line 86 in region 66 corresponding to the intermediate layer 32 is determined. Furthermore, the measurement depth corresponding to the intersection point 802 is determined as the distance in the thickness direction between the radially outer interface 352 of the carbon-rich layer 35 and the surface 121 of the carbon film 12. That is, the position of the interface 352 of the carbon-rich layer 35 in the thickness direction is determined from the measurement depth corresponding to the intersection point 802.

[0091] Furthermore, the distance in the thickness direction between the interface 351 and the interface 352 of the carbon-rich layer 35 is taken as the thickness of the carbon-rich layer 35 in the thickness direction (hereinafter also simply referred to as "thickness"). In addition, regarding the thickness of the low-carbon layer 36, the position of the inner side surface 331 of the surface layer 33 in the thickness direction, which is determined by the method described later, is obtained as the distance in the thickness direction between the interface 351 of the carbon-rich layer 35 and the inner side surface 331 of the surface layer 33.

[0092] The thickness of the surface layer 33 is determined based on SEM images of the sample cross-section. Specifically, for the surface layer 33, the thickness at any number (e.g., 5) measurement locations on the SEM image is calculated, and the arithmetic mean of the thicknesses at these multiple measurement locations is taken as the thickness of the surface layer 33. The thickness of the surface layer 33 at each measurement location is determined by the position of the inner surface 331 and the radially outer interface 332 of the surface layer 33 in the thickness direction, based on the contrast difference and other parameters in the SEM image.

[0093] The thickness of the carbon film 12 is also determined based on the SEM image of the sample cross-section, similar to the thickness of the surface layer 33. Specifically, for the carbon film 12, the thickness is calculated at any number (e.g., 5) measurement locations on the SEM image, and the arithmetic mean of the thicknesses at these multiple measurement locations is taken as the thickness of the carbon film 12. The thickness of the carbon film 12 at each measurement location is determined by the position of the surface 121 of the carbon film 12 and the radially outer interface (i.e., the inner surface 331 of the surface layer 33) in the thickness direction, based on the contrast difference, etc., in the SEM image.

[0094] The relationship between measurement depth and carbon content in carbon film composite 1 is not necessarily limited to Figure 6A The form shown can also be varied in many ways. For example, in Figure 7A In the example shown, the carbon content indicated by line 8a is approximately constant in the low-carbon layer 36. Furthermore, the carbon content in the carbon-rich layer 35 increases radially outward from the interface 351 between the low-carbon layer 36 and the carbon-rich layer 35, remains approximately constant in the central portion of the carbon-rich layer 35 in the thickness direction, and decreases near the interface 352 (i.e., the interface 332 between the surface layer 33 and the intermediate layer 32) on the radially outer side of the carbon-rich layer 35, approaching interface 352. The carbon content in the intermediate layer 32 decreases with increasing measurement depth.

[0095] In this case, in order to approximate with multiple straight lines Figure 7A The broken line 8a is temporarily divided into 6 boundary lines 60, dividing the horizontal axis into 7 regions 61a to 67a. Figure 7A In the example shown, regions 61a and 62a roughly correspond to carbon film 12, region 63a roughly corresponds to low carbon layer 36, regions 64a, 65a, and 66a roughly correspond to carbon rich layer 35, and region 67a roughly corresponds to intermediate layer 32.

[0096] Next, with Figure 6A The examples shown are roughly the same, such as Figure 7B As shown, the portions of the broken line 8a corresponding to each region 61a-67a are approximated by approximate straight lines 81a-87a, and a total determination coefficient is obtained. Subsequently, the positions of multiple boundary lines 60 are repeatedly changed and the total determination coefficient is obtained. The position of the boundary line 60 with the largest total determination coefficient is determined as the appropriate position of the boundary line 60.

[0097] Next, as Figure 7CAs shown, the intersection point 801a of the approximate straight line 83a in region 63a corresponding to the low-carbon layer 36 and the approximate straight line 84a in region 64a corresponding to the carbon-rich layer 35 is determined. Furthermore, the position of the radially inner interface 351 of the carbon-rich layer 35 in the thickness direction is determined from the measurement depth corresponding to the intersection point 801a. Additionally, the intersection point 802a of the approximate straight line 86a in region 66a corresponding to the carbon-rich layer 35 and the approximate straight line 87a in region 67a corresponding to the intermediate layer 32 is determined. Furthermore, the position of the radially outer interface 352 of the carbon-rich layer 35 in the thickness direction is determined from the measurement depth corresponding to the intersection point 802a. Then, in approximately the same manner as above, the thicknesses of the carbon-rich layer 35 and the low-carbon layer 36 are determined.

[0098] exist Figure 8A In the example shown, the carbon content indicated by line 8b decreases approximately with increasing measurement depth in the low-carbon layer 36, and exhibits multiple peaks 831 along its path. In this case, to avoid confusion between these peaks 831 and the carbon content peak 841 in the carbon-rich layer 35, the outermost radially located peak among the multiple peaks 831 and 841 is considered peak 841 in the carbon-rich layer 35, and the other peaks are considered peaks in the low-carbon layer 36. Subsequently, to ensure that peak 841 is contained within regions 84b–85b corresponding to the carbon-rich layer 35, and the other peaks 831 are contained within region 83b corresponding to the low-carbon layer 36, five boundary lines 60 are temporarily established, aligning the horizontal axis with… Figure 6A Similarly, it is divided into 6 regions 61b to 66b.

[0099] Next, with Figure 6A The examples shown are roughly the same, such as Figure 8B As shown, the approximate straight lines 81b to 86b are used to approximate the portions of the broken line 8b corresponding to each region 61b to 66b, respectively, to obtain a total determination coefficient. Subsequently, the positions of multiple boundary lines 60 are repeatedly changed and the total determination coefficient is obtained. The position of the boundary line 60 with the largest total determination coefficient is determined as the appropriate position of the boundary line 60.

[0100] Next, as Figure 8C As shown, the intersection point 801b of the approximate straight line 83b in region 63b corresponding to the low-carbon layer 36 and the approximate straight line 84b in region 64b corresponding to the carbon-rich layer 35 is determined. Furthermore, the position of the radially inner interface 351 of the carbon-rich layer 35 in the thickness direction is determined from the measurement depth corresponding to the intersection point 801b. Additionally, the intersection point 802b of the approximate straight line 85b in region 65b corresponding to the carbon-rich layer 35 and the approximate straight line 86b in region 66b corresponding to the intermediate layer 32 is determined. Furthermore, the position of the radially outer interface 352 of the carbon-rich layer 35 in the thickness direction is determined from the measurement depth corresponding to the intersection point 802b. Then, in approximately the same manner as above, the thicknesses of the carbon-rich layer 35 and the low-carbon layer 36 are determined.

[0101] exist Figure 9A In the example shown, the carbon content, as indicated by line 8c, increases with increasing measurement depth from the surface 121 of the carbon film 12, and decreases with increasing measurement depth near the inner surface 331 of the surface layer 33. In this case, compared with... Figure 6A The example shown is roughly the same, temporarily setting 5 boundary lines 60 to divide the horizontal axis into 6 regions 61c to 66c.

[0102] Next, with Figure 6A The examples shown are roughly the same, such as Figure 9B As shown, the approximate straight lines 81c to 86c are used to approximate the portions of the broken line 8c corresponding to each region 61c to 66b, respectively, to obtain the total determination coefficient. Subsequently, the positions of multiple boundary lines 60 are repeatedly changed and the total determination coefficient is obtained. The position of the boundary line 60 with the largest total determination coefficient is determined as the appropriate position of the boundary line 60.

[0103] Next, as Figure 9C As shown, the intersection point 801c of the approximate straight line 83c in region 63c corresponding to the low-carbon layer 36 and the approximate straight line 84c in region 64c corresponding to the carbon-rich layer 35 is determined. Furthermore, the position of the radially inner interface 351 of the carbon-rich layer 35 in the thickness direction is determined from the measurement depth corresponding to the intersection point 801c. Additionally, the intersection point 802c of the approximate straight line 85c in region 65c corresponding to the carbon-rich layer 35 and the approximate straight line 86c in region 66c corresponding to the intermediate layer 32 is determined. Furthermore, the position of the radially outer interface 352 of the carbon-rich layer 35 in the thickness direction is determined from the measurement depth corresponding to the intersection point 802c. Then, in approximately the same manner as above, the thicknesses of the carbon-rich layer 35 and the low-carbon layer 36 are determined.

[0104] The maximum carbon content in the carbon-rich layer 35 is, for example, more than 1.1 times and less than 4.0 times the average carbon content in the low-carbon layer 36 (i.e., the region between the surface of the support 11 and the carbon-rich layer 35). Preferably, the maximum carbon content in the carbon-rich layer 35 is more than 1.2 times and less than 2.0 times the average carbon content in the low-carbon layer 36. Furthermore, the maximum carbon content in the carbon-rich layer 35 is, for example, more than 0.05 times and less than 0.25 times the maximum carbon content in the carbon film 12. Preferably, the maximum carbon content in the carbon-rich layer 35 is more than 0.05 times and less than 0.21 times the maximum carbon content in the carbon film 12.

[0105] The maximum carbon content in the aforementioned carbon-rich layer 35 refers to the highest carbon content within the carbon-rich layer 35. Specifically, Figures 6A to 9A The peak values ​​of the broken lines 8, 8a, 8b, and 8c shown in the carbon-rich layer 35 represent the maximum carbon content in the carbon-rich layer 35.

[0106] The average carbon content in the low-carbon layer 36 refers to the average carbon content at the central portion along the thickness direction of the low-carbon layer 36. The average carbon content of the low-carbon layer 36 is obtained as follows: First, in the aforementioned broken line 8 (and similarly for broken lines 8a to 8c), points are determined radially inward and radially outward from the center along the thickness direction of the portion contained in the low-carbon layer 36 at a distance equal to 10% of the thickness of the low-carbon layer 36. Then, the arithmetic mean of the carbon content between these two points is calculated, and this arithmetic mean is taken as the average carbon content in the low-carbon layer 36.

[0107] The maximum carbon content in carbon film 12 refers to the highest carbon content within carbon film 12. Specifically, Figures 6A to 9A The maximum values ​​of the broken lines 8, 8a, 8b, and 8c shown in the carbon film 12 are the maximum carbon content in the carbon film 12.

[0108] Next, refer to Figure 10 and Figures 11A to 11D The manufacturing process of carbon film composite 1 will be explained. Figure 10 This is an example of the manufacturing process of carbon film composite 1. Figures 11A to 11D This is a schematic representation of a portion of the cross-section of the carbon film composite 1 during the manufacturing process.

[0109] In manufacturing the carbon film composite 1, firstly, a support 11 is prepared (step S11). In step S11, for example, the raw material of the substrate 31 is formed by extrusion molding or the like, and then fired to form a substrate 31 with an integral structure. Next, an intermediate layer 32 and a surface layer 33 are formed on the inner side of the through-holes of the substrate 31 by filtration film forming or the like, and then fired to form the aforementioned support 11 for later use.

[0110] Next, a first precursor solution is applied to the support 11 from the inner side of the compartment 111 (i.e., the inner side 331 of the surface layer 33). The first precursor solution contains a first precursor of carbon intended to form the carbon-rich layer 35. The first precursor solution permeates into the support 11 from the surface layer 33 side. Thus, as... Figure 11A As shown, a first precursor layer 71 containing a first precursor is formed inside the support 11 (step S12). Figure 11A In the middle, parallel oblique lines are marked on the first precursor layer 71 ( Figures 11B to 11D (The same applies). The support 11, on which the first precursor layer 71 is formed, is dried, for example, by air supply or a dryer. The drying of the support 11 is carried out, for example, at room temperature (25°C) to 90°C for 5 to 120 minutes.

[0111] The first precursor may be, for example, a thermosetting resin such as phenolic resin, melamine resin, urea resin, furan resin, polyimide resin, or epoxy resin; a thermoplastic resin such as polyethylene, polyphenylene ether, or polyetherimide; a cellulose-based resin; or an inherently microporous polymer (PIM). Alternatively, the first precursor may be a precursor material of these resins. In this embodiment, phenolic resin is used as the first precursor.

[0112] The first precursor solution is obtained by mixing or dissolving the first precursor in a solvent. This solvent may be, for example, an organic solvent such as methanol, ethanol, acetone, tetrahydrofuran, NMP (N-methyl-2-pyrrolidone), or toluene, or water. In this embodiment, ethanol is used as the solvent. It should be noted that the first precursor contained in the first precursor solution and the solvent are not limited to the examples described above and various modifications can be made.

[0113] The application of the first precursor solution in step S12 is performed, for example, by a flow-down method, an immersion method, a dip coating method, a spin coating method, a drop coating method, a spray coating method, or a filter coating method. In this embodiment, the application of the first precursor solution is performed by a flow-down method. Specifically, the support body 11 is placed with its length direction approximately parallel to the direction of gravity, and the first precursor solution flows in from the upper opening of each compartment 111, thereby bringing the first precursor solution into contact with the inner surface of each compartment 111, and thus applying the first precursor solution to the support body 11.

[0114] The first precursor solution, which seeps into the surface layer 33 from the inner side of compartment 111, stops at the interface 332 between the surface layer 33 and the intermediate layer 32 due to the difference in average pore size between the surface layer 33 and the intermediate layer 32, and does not actually enter the intermediate layer 32. Therefore, the radially outer end of the first precursor layer 71, as... Figure 11A It is shown at approximately the same position radially as interface 332. Figure 11A In the example shown, the radial inner end of the first precursor layer 71 is located at approximately the same position radially as the inner side surface 331 of the surface layer 33.

[0115] It should be noted that, Figure 11A In the example shown, the first precursor layer 71 is formed on the surface layer 33 almost entirely, but is not limited thereto. For example, by adjusting the amount of the first precursor solution applied to the support 11, the radially outer end of the first precursor layer 71 can be positioned radially inward from the interface 332 between the surface layer 33 and the intermediate layer 32.

[0116] After step S12 is completed, a portion of the first precursor layer 71 disposed inside the support 11 is removed (step S13). Specifically, for example, the support 11 is placed in a manner where its length direction is approximately parallel to the direction of gravity, and the removal treatment liquid flows in from the upper opening of each compartment 111, causing the removal treatment liquid to contact the inner surface of each compartment 111. The removal treatment liquid seeps into the support 11 from the inner surface of the compartment 111 (i.e., the inner surface 331 of the surface layer 33). Thus, as Figure 11B As shown, the radially inner portion of the first precursor layer 71 is dissolved by removing the processing liquid and removed from the support 11. In other words, the first precursor layer 71 is partially removed from the inner side of the compartment 111 (i.e., the surface of the support 11).

[0117] The removal treatment liquid is a liquid capable of dissolving the first precursor. The removal treatment liquid is preferably a liquid with a low boiling point and high volatility. Examples of removal treatment liquids include organic solvents such as methanol, ethanol, acetone, tetrahydrofuran, NMP (N-methyl-2-pyrrolidone), or toluene. For example, a solvent for the first precursor solution (ethanol in this embodiment) is used as the removal treatment liquid. It should be noted that the removal treatment liquid is not limited to a solvent for the first precursor solution and can be any liquid capable of removing the first precursor layer 71.

[0118] In step S13, the radially outer portion of the first precursor layer 71 formed in step S12 is not removed by the removal treatment liquid and remains inside the support 11. The radially inner end of the first precursor layer 71 remaining inside the support 11 is located radially between the inner side surface 331 of the surface layer 33 and the interface 332 of the surface layer 33 and the intermediate layer 32. It should be noted that the radially outer end of the first precursor layer 71 remaining inside the support 11 is located at approximately the same position radially as the interface 332 of the surface layer 33 and the intermediate layer 32. The support 11 with the first precursor layer 71 remaining inside is dried, for example, by air supply or a dryer. The drying of the support 11 is carried out, for example, at room temperature (25°C) to 90°C for 5 to 120 minutes.

[0119] After step S13 is completed, the dried support 11 is subjected to heat treatment, and the first precursor layer 71 remaining inside the support 11 is cured (step S14). Specifically, for example, the support 11 is heated at 90°C to 500°C using a dryer and held for 0.5 hours to 72 hours, thereby curing the first precursor layer 71. The curing of the first precursor layer 71 in step S14 can be carried out by other methods.

[0120] After step S14 is completed, a second precursor solution is applied to the support 11 from the inner side of the compartment 111 (i.e., the inner side 331 of the surface layer 33). The second precursor solution contains a second precursor of carbon, which is intended to form the carbon film 12. The second precursor solution permeates into the support 11 from the surface layer 33 side. Thus, as Figure 11C As shown, a second precursor layer 72 containing a second precursor is formed inside the support 11. Figure 11C In the text, the second precursor layer 72 is marked with parallel oblique lines that are different from those of the first precursor layer 71. Figure 11D (Same as above).

[0121] The second precursor may be, for example, a thermosetting resin such as phenolic resin, melamine resin, urea resin, furan resin, polyimide resin, or epoxy resin; a thermoplastic resin such as polyethylene, polyphenylene ether, or polyetherimide; a cellulose-based resin; or an inherently microporous polymer (PIM). Alternatively, the second precursor may be a precursor material of these resins. In this embodiment, phenolic resin is used as the second precursor.

[0122] The second precursor solution is obtained by mixing or dissolving the second precursor in a solvent. This solvent may be, for example, an organic solvent such as methanol, ethanol, acetone, tetrahydrofuran, NMP (N-methyl-2-pyrrolidone), or toluene, or water. In this embodiment, ethanol is used as the solvent. It should be noted that the second precursor and solvent contained in the second precursor solution are not limited to the examples described above and various modifications can be made. Furthermore, the second precursor and solvent contained in the second precursor solution may be the same substances as the first precursor and solvent contained in the first precursor solution, or they may be different substances.

[0123] The application of the second precursor solution described above can be performed, for example, by a flow-down method, an impregnation method, a dip coating method, a spin coating method, a drop coating method, a spray coating method, or a filter coating method. In this embodiment, the application of the second precursor solution is performed by a flow-down method. Specifically, the support body 11 is placed with its length direction approximately parallel to the direction of gravity, and the second precursor solution flows in from the upper opening of each compartment 111, so that the second precursor solution contacts the inner surface of each compartment 111, thereby applying the second precursor solution to the support body 11. It should be noted that the application of the second precursor solution can be performed using the same method as the application of the first precursor solution described above, or it can be performed using a different method.

[0124] exist Figure 11CIn the example shown, the radially outer end of the second precursor layer 72 contacts the radially inner end of the first precursor layer 71. As described above, the first precursor layer 71 is cured in step S14. Therefore, even if the second precursor solution comes into contact with the first precursor layer 71, there will be no substantial mixing of the second precursor solution toward the first precursor layer 71 or dissolution of the first precursor layer 71. It should be noted that, because the solvent of the second precursor solution is different from that of the first precursor solution, even if the first precursor layer 71 is not cured, there will be no substantial mixing of the second precursor solution toward the first precursor layer 71 or dissolution of the first precursor layer 71. In such cases, the curing of the first precursor layer 71 in step S14 may be omitted.

[0125] The first precursor layer 71 and the second precursor layer 72 are respectively the portions of the carbon film composite 1 that are intended to be the carbon-rich layer 35 and the low-carbon layer 36. Therefore, when the first precursor contained in the first precursor solution and the second precursor contained in the second precursor solution are the same substance (e.g., phenolic resin), the concentration of the second precursor in the second precursor solution is lower than the concentration of the first precursor in the first precursor solution. Furthermore, when the first precursor contained in the first precursor solution and the second precursor contained in the second precursor solution are different substances, for example, the carbon residue of the second precursor is lower than the carbon residue of the first precursor. This carbon residue refers to the ratio of the amount of carbon remaining after carbonization treatment to the amount of precursor (i.e., the first precursor or the second precursor) before carbonization treatment in step S16 described later. It should be noted that the second precursor solution may contain a second precursor with a higher carbon residue than the first precursor at a concentration lower than the concentration of the first precursor in the first precursor solution.

[0126] The support 11, with the second precursor layer 72 formed inside, is dried, for example, by means of air supply or a dryer. The drying of the support 11 is performed, for example, at room temperature (25°C) to 90°C for 5 to 120 minutes. The dried support 11 is then subjected to a heat treatment, which cures the second precursor layer 72 inside the support 11. This heat treatment is performed, for example, in a manner substantially similar to the heat treatment in step S14. Specifically, the support 11 is heated to 90°C to 500°C using a dryer and held for 0.5 hours to 72 hours, thereby curing the second precursor layer 72.

[0127] exist Figure 11C In the example shown, the second precursor layer 72 is formed almost entirely in the surface layer 33 at a radially inward portion compared to the first precursor layer 71. In other words, the radially inward end of the second precursor layer 72 is located at approximately the same position radially as the inner surface 331 of the surface layer 33, which is the interface between the surface layer 33 and the predetermined carbon film 12. Forming the carbon film 12 cannot be achieved by applying the second precursor solution and performing the aforementioned heat treatment only once. Figure 11C In the case of the second precursor layer 72 shown (i.e., when the radial thickness of the second precursor layer 72 is insufficient), by repeatedly applying the second precursor solution and performing the heating treatment described above multiple times, a mixture can be formed. Figure 11C The second precursor layer 72 is shown.

[0128] Next, a second precursor solution is applied again to the support 11 from the inner side of the compartment 111 (i.e., the inner side 331 of the surface layer 33). The second precursor solution adheres to the inner side 331 of the surface layer 33, where the second precursor layer 72 is formed. Thus, as... Figure 11D As shown, a thin film containing the second precursor, namely the second precursor film 73, is formed on the inner side 331 of the surface layer 33 (i.e., the surface of the support 11) (step S15). Figure 11D In the diagram, the second precursor membrane 73 is marked with the same parallel oblique line as the second precursor layer 72.

[0129] The support 11, to which the second precursor film 73 is disposed, is dried, for example, by means of air supply or a dryer. The drying of the support 11 is performed, for example, at room temperature (25°C) for 5 to 120 minutes. The dried support 11 is then subjected to a heat treatment, which cures the second precursor film 73 on the surface of the support 11. This heat treatment is performed, for example, in a manner substantially similar to the heat treatment performed on the second precursor layer 72. For example, the support 11 is heated to 90°C to 500°C and held for 0.5 hours to 72 hours, thereby curing the second precursor film 73.

[0130] If the thickness of the second precursor film 73 does not reach the desired thickness when the second precursor solution is applied and the above-mentioned heat treatment is performed only once during the formation of the second precursor film 73, the film thickness can be increased by repeatedly applying the second precursor solution and performing the heat treatment. Figure 11D The second precursor film 73 is shown. Alternatively, if the second precursor layer 72 and the second precursor film 73 can be formed by applying the second precursor solution and heating once, the above-mentioned drying and heating treatments can be omitted between the formation of the second precursor layer 72 and the formation of the second precursor film 73.

[0131] After step S15 is completed, a carbonization treatment is performed on the support 11 on which the first precursor layer 71, the second precursor layer 72, and the second precursor film 73 are disposed. As a result, a carbon-rich layer 35 is formed from the first precursor layer 71 inside the support 11, and a low-carbon layer 36 is formed from the second precursor layer 72. Furthermore, a carbon film 12 is formed from the second precursor film 73 on the surface of the support 11. As a result, a carbon film composite 1 having the carbon-rich layer 35, the low-carbon layer 36, and the carbon film 12 is obtained (step S16).

[0132] In the carbonization process of step S16, for example, the support 11, on which the first precursor layer 71, the second precursor layer 72, and the second precursor film 73 are disposed, is placed in an electric furnace and heated to 400°C to 1200°C, and held for 0.5 hours to 200 hours. By setting the carbonization temperature to above 400°C, the second precursor film 73 can be carbonized well and fine pores can be formed, and the separation coefficient of the carbon film 12 is within a preferred range. By setting the carbonization temperature to below 1200°C, excessive densification of the carbon film 12 can be suppressed, and the separation coefficient of the carbon film 12 is within a preferred range. It should be noted that the preferred carbonization temperature is 600°C to 900°C.

[0133] The carbonization treatment described above is preferably carried out in a non-oxidizing atmosphere. A non-oxidizing atmosphere refers to an atmosphere in which the first precursor and the second precursor are not oxidized when carbonized within the aforementioned temperature range. Specifically, this non-oxidizing atmosphere is an inert gas atmosphere such as nitrogen or argon, or a vacuum atmosphere.

[0134] Next, refer to Figure 12 The separation of the mixture using carbon film composite 1 is explained. Figure 12 This is a cross-sectional view showing the separation device 2. Figure 12 In the figure, for ease of understanding, the cross-section of the carbon film composite 1 is schematically represented in a simplified manner.

[0135] In the separation device 2, a mixture containing multiple fluids (i.e., gases or liquids) is supplied to the carbon membrane composite 1, causing highly permeable substances in the mixture to permeate through the carbon membrane composite 1, thereby separating them from the mixture. The separation in the separation device 2 can be performed, for example, to extract highly permeable substances (hereinafter also referred to as "highly permeable substances") from the mixture, or to concentrate substances with low permeability (hereinafter also referred to as "lowly permeable substances").

[0136] The mixture (i.e. the mixed fluid) can be a mixture of gases containing multiple gases, a mixture of liquids containing multiple liquids, or a two-phase fluid containing both gases and liquids.

[0137] Mixtures may include, for example, one or more of the following: hydrogen (H2), helium (He), nitrogen (N2), oxygen (O2), water (H2O), carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides, ammonia (NH3), sulfur oxides, hydrogen sulfide (H2S), sulfur fluoride, mercury (Hg), arsine (AsH3), hydrogen cyanide (HCN), carbonyl sulfide (COS), C1-C8 hydrocarbons, organic acids, alcohols, thiols, esters, ethers, ketones, and aldehydes. Highly permeable substances may include, for example, one or more of CO2, NH3, and H2O. It should be noted that mixtures and highly permeable substances include substances other than those listed above.

[0138] Nitrogen oxides refer to compounds of nitrogen and oxygen. Examples of nitrogen oxides include nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide (also known as dinitrogen monoxide) (N2O), dinitrogen trioxide (N2O3), dinitrogen tetroxide (N2O4), and dinitrogen pentoxide (N2O5), all collectively referred to as NO. X (Nox) substances.

[0139] Sulfur oxides are compounds formed from sulfur and oxygen. Examples of sulfur oxides include sulfur dioxide (SO2) and sulfur trioxide (SO3), collectively referred to as SO42-SO ... X (Sox) substances.

[0140] Sulfur fluoride refers to compounds of fluorine and sulfur. Examples of sulfur fluoride include disulfur difluoride (FSSF, S=SF2), sulfur difluoride (SF2), sulfur tetrafluoride (SF4), sulfur hexafluoride (SF6), or disulfur decafluoride (S2F). 10 )wait.

[0141] Hydrocarbons with C1 to C8 carbon atoms are defined as hydrocarbons with one or more but fewer than eight carbon atoms. Hydrocarbons with C3 to C8 carbon atoms can be any of the following: straight-chain compounds, branched-chain compounds, and cyclic compounds. Additionally, hydrocarbons with C2 to C8 carbon atoms can be any of the following: saturated hydrocarbons (i.e., hydrocarbons without double or triple bonds) and unsaturated hydrocarbons (i.e., hydrocarbons with double and / or triple bonds). Examples of hydrocarbons with C1 to C4 carbon atoms include methane (CH4), ethane (C2H6), ethylene (C2H4), propane (C3H8), propylene (C3H6), n-butane (CH3(CH2)2CH3), isobutane (CH(CH3)3), 1-butene (CH2=CHCH2CH3), 2-butene (CH3CH=CHCH3), or isobutene (CH2=C(CH3)2).

[0142] The aforementioned organic acids are carboxylic acids or sulfonic acids, etc. Examples of carboxylic acids include formic acid (CH2O2), acetic acid (C2H4O2), oxalic acid (C2H2O4), acrylic acid (C3H4O2), or benzoic acid (C6H5COOH), etc. Examples of sulfonic acids include ethanesulfonic acid (C2H6O3S), etc. These organic acids can be chain compounds or cyclic compounds.

[0143] The alcohols mentioned above include, for example, methanol (CH3OH), ethanol (C2H5OH), isopropanol (2-propanol) (CH3CH(OH)CH3), ethylene glycol (CH2(OH)CH2(OH)) or butanol (C4H9OH), etc.

[0144] Thiols are organic compounds with hydrogenated sulfur (SH) at their terminals, also known as Thiol or Thioalcohol. Examples of thiols include methylthiol (CH3SH), ethylthiol (C2H5SH), or 1-propanethiol (C3H7SH).

[0145] The esters mentioned above are, for example, formate esters or acetate esters.

[0146] The ethers mentioned above are, for example, dimethyl ether ((CH3)2O), methyl ethyl ether (C2H5OCH3), or diethyl ether ((C2H5)2O), etc.

[0147] The ketones mentioned above include, for example, acetone ((CH3)2CO), methyl ethyl ketone (C2H5COCH3), or diethyl ketone ((C2H5)2CO).

[0148] The aldehydes mentioned above include acetaldehyde (CH3CHO), propionaldehyde (C2H5CHO), or butylaldehyde (C3H7CHO), etc.

[0149] like Figure 12 As shown, the separation device 2 includes: a carbon film composite 1, a sealing part 21, a housing 22, and two sealing components 23. The carbon film composite 1, the sealing part 21, and the sealing components 23 are housed within the housing 22. Figure 12 In the diagram, parallel oblique lines are used to mark the support 11 and carbon film 12 of the carbon film composite 1. The internal space of the outer shell 22 is a sealed space isolated from the space surrounding the outer shell 22. A supply unit 26, a first recovery unit 27, and a second recovery unit 28 are connected to the outer shell 22.

[0150] The sealing part 21 is installed in the longitudinal direction of the support body 11 as described above (i.e., Figure 12The sealing part 21 is a component that covers and seals the two ends of the support body 11 along its length and a portion of the outer surface near those two ends. In this embodiment, the sealing part 21 is a glass seal with a thickness of 10 μm to 50 μm. The material and shape of the sealing part 21 can be appropriately modified. It should be noted that the sealing part 21 has multiple openings that coincide with the multiple compartments 111 of the support body 11, so that the two ends of each compartment 111 along its length are not covered by the sealing part 21. Therefore, it is possible for fluid to flow in and out from these two ends toward the compartment 111.

[0151] The outer casing 22 is a generally cylindrical cylindrical component. The outer casing 22 is formed, for example, of stainless steel or carbon steel. The length direction of the outer casing 22 is generally parallel to the length direction of the carbon film composite 1. At one end of the length direction of the outer casing 22 (i.e., Figure 12 A supply port 221 is provided at the left end of the housing 22, and a first discharge port 222 is provided at the other end. A supply unit 26 is connected to the supply port 221. A first recovery unit 27 is connected to the first discharge port 222. A second discharge port 223 is provided on the side of the housing 22. A second recovery unit 28 is connected to the second discharge port 223. It should be noted that the shape and material of the housing 22 can be varied.

[0152] Two sealing components 23 are disposed near both ends of the carbon film composite 1 along its length, between the outer surface of the carbon film composite 1 and the inner surface of the outer shell 22. Each sealing component 23 is a generally annular component formed of a gas- and liquid-impermeable material. The sealing component 23 may be, for example, an O-ring or a gasket formed of a flexible resin. The sealing components 23 are tightly fitted around the entire circumference of the carbon film composite 1 on both the outer surface of the carbon film composite 1 and the inner surface of the outer shell 22. Figure 12 In the example shown, the sealing member 23 is sealed to the outer side of the sealing portion 21, and indirectly sealed to the outer side of the carbon film composite 1 through the sealing portion 21. It should be noted that the sealing member 23 can be directly sealed to the outer side of the carbon film composite 1. The sealing member 23 is sealed to the outer side of the carbon film composite 1 or the sealing portion 21, and to the inner side of the housing 22, preventing the passage of gas and liquid. It should be noted that the material of the sealing member 23, besides resin, can be carbon, metal, or other inorganic materials.

[0153] The supply unit 26 supplies the mixture into the interior space of the outer casing 22 via the supply port 221. The supply unit 26 may include, for example, a blower or pump for pressurizing the mixture toward the outer casing 22. This pressurizing mechanism may include, for example, a temperature regulating unit and a pressure regulating unit for adjusting the temperature and pressure of the mixture supplied to the outer casing 22. The first recovery unit 27 and the second recovery unit 28 may include, for example, a storage container for storing the material discharged from the outer casing 22, or a blower or pump for transferring the material.

[0154] When separating the mixture, firstly, a carbon film composite 1 is prepared. Specifically, the carbon film composite 1 is installed inside the housing 22. Next, a mixture containing multiple substances with different permeabilities to the carbon film 12, as shown by arrow 251, is supplied to the inside of the housing 22 via the supply unit 26. For example, the mixture is a liquid obtained by mixing multiple liquids. The main components of this liquid are, for example, water and ethanol. The liquid may contain liquids other than water and ethanol.

[0155] The mixture supplied from the supply section 26 to the outer casing 22 is introduced from the left end of the carbon film composite 1 in the figure into each compartment 111 of the support 11. The highly permeable substance in the mixture, i.e., the high-permeability substance, permeates through the carbon film 12 provided on the inner surface of each compartment 111 and the support 11 and is discharged from the outer surface of the support 11. Thus, the highly permeable substance (e.g., water) is separated from the less permeable substance in the mixture, i.e., the low-permeability substance (e.g., ethanol).

[0156] The material discharged from the outer side of the support 11 (hereinafter referred to as "permeable material") is guided to the second recovery section 28 via the second discharge port 223 as shown by arrow 253, and is recovered by the second recovery section 28. In addition to the high permeability material described above, the permeable material may contain low permeability material that has already permeated through the carbon film 12.

[0157] In addition, substances in the mixture other than those that have permeated through the carbon film 12 and the support 11 (hereinafter referred to as "non-permeable substances") pass from left to right in each compartment 111 of the support 11 as shown by arrow 252, and are recovered by the first recovery unit 27 via the first discharge port 222. The non-permeable substances may include, in addition to the aforementioned low-permeability substances, high-permeability substances that do not permeate through the carbon film 12. The non-permeable substances recovered by the first recovery unit 27 can, for example, be recycled to the supply unit 26 and resupplyed into the outer casing 22.

[0158] Next, the carbon film composite 1a according to the second embodiment of the present invention will be described. Figure 13 This is an enlarged cross-sectional view of the area near the carbon film 12 of the carbon film composite 1a. Except for the location of the carbon-rich layer 35, which differs from the previous view. Figure 4 and Figure 5 Except where shown, carbon film composite 1a has a structure substantially the same as that of carbon film composite 1. In the following description, the components of carbon film composite 1a that correspond to the components of carbon film composite 1 are labeled with the same reference numerals.

[0159] exist Figure 13 In the example shown, the carbon-rich layer 35 is substantially entirely disposed inside the intermediate layer 32. In other words, the carbon-rich layer 35 is substantially entirely located between the interface 332 of the surface layer 33 and the intermediate layer 32 and the interface 322 of the intermediate layer 32 and the substrate 31. Further, the carbon-rich layer 35 is substantially located on the opposite side of the inner surface 331 of the surface layer 33 relative to the interface 332 between the surface layer 33 and the intermediate layer 32 (i.e., in the aforementioned thickness direction, the opposite side of the inner surface 331 is the radially outer side).

[0160] exist Figure 13 In the example shown, the radially inner interface 351 of the carbon-rich layer 35 is located radially outer (i.e., away from the compartment 111) of the interface 332 between the surface layer 33 and the intermediate layer 32, and is separated from the interface 332. Furthermore, the radially outer interface 352 of the carbon-rich layer 35 is located radially inner (separated from the interface 322 between the intermediate layer 32 and the substrate 31) of the intermediate layer 32, and is separated from the interface 322.

[0161] In the carbon film composite 1a, in the intermediate layer 32, the carbon content from the radially inner interface 351 of the carbon-rich layer 35 to the interface 332 between the surface layer 33 and the intermediate layer 32 is less than the carbon content of the carbon-rich layer 35. Furthermore, the carbon content in the surface layer 33 is also less than the carbon content of the carbon-rich layer 35. That is, in Figure 13 In the example shown, the low-carbon layer 36 is composed of the entire surface layer 33 and a portion of the intermediate layer 32 from the radially inner interface 351 of the carbon-rich layer 35 to the interface 332 between the surface layer 33 and the intermediate layer 32. It should be noted that in the intermediate layer 32, the carbon content from the radially outer interface 352 of the carbon-rich layer 35 to the interface 322 between the intermediate layer 32 and the substrate 31 is also lower than the carbon content of the carbon-rich layer 35.

[0162] The thickness of the carbon-rich layer 35 in the thickness direction (i.e., the direction perpendicular to the surface of the support 11) is, for example, 0.01 μm or more and 15 μm or less, preferably 0.01 μm or more and 10 μm or less. The sum of the thickness of the low-carbon layer 36 and the thickness of the carbon-rich layer 35 (i.e., the sum of the thickness from the inner side surface 331 of the surface layer 33 to the thickness of the carbon-rich layer 35 and the thickness of the carbon-rich layer 35) is, for example, 1 μm or more and 1000 μm or less.

[0163] Next, refer to Figure 14 and Figures 15A-15CThe manufacturing method of carbon film composite 1a is described. Figure 14 This is a diagram illustrating an example of the manufacturing process of carbon film composite 1a. Figures 15A-15C This is a schematic diagram showing a partial cross-section of the carbon film composite 1a during the manufacturing process.

[0164] In manufacturing the carbon film composite 1a, firstly, in step S11 described above (refer to...) Figure 10 Similarly, prepare the support body 11 (step S21).

[0165] Next, pressure is reduced around the outer surface of the support 11 (i.e., the space radially outward from the outer surface of the support 11). Specifically, for example, the outer surface of the support 11 is substantially entirely covered by a generally cylindrical shell made of stainless steel or the like. The inner diameter of this shell is larger than the outer diameter of the support 11, thus creating a generally cylindrical space (hereinafter also referred to as the "outer peripheral space") circumferentially between the inner surface of the shell and the outer surface of the support 11. At both ends of the support 11 along its length, O-rings or the like are provided between the inner surface of the shell and the outer surface of the support 11, and the aforementioned outer peripheral space is airtightly sealed. This outer peripheral space is depressurized using a pressure-reducing pump or the like connected to the shell. As a result, the pressure in the surface layer 33 and the intermediate layer 32 of the support 11 decreases as it moves radially outward from the inner surface 331 of the surface layer 33. The pressure in the outer peripheral space is, for example, 0 kPa to 90 kPa.

[0166] Furthermore, for the support 11 in a state where the outer peripheral space is depressurized, similarly to step S12, a first precursor solution is applied from the inner side of the compartment 111 (i.e., the inner side 331 of the surface layer 33). As described above, the first precursor solution contains a first precursor of carbon intended to become the carbon-rich layer 35. The first precursor solution permeates into the support 11 from the surface layer 33 side. Thus, as... Figure 15A As shown, a first precursor layer 71 containing a first precursor is formed inside the support 11 (step S12). Figure 15A In the middle, parallel oblique lines are marked on the first precursor layer 71 ( Figures 15B-15C (Same as above).

[0167] The first precursor solution, which seeps into the surface layer 33 from the inner side of compartment 111, moves from the surface layer 33 to the intermediate layer 32 due to the decompression of the outer peripheral space, and is located radially inward of the substrate 31 within the intermediate layer 32 (i.e., between interface 332 and interface 322). The support 11, on which the first precursor layer 71 is formed in the intermediate layer 32, is dried, for example, by air supply or a dryer. The drying of the support 11 is carried out, for example, at room temperature (25°C) to 90°C for 5 to 120 minutes. It should be noted that the radial position of the first precursor layer 71 in the intermediate layer 32 can be adjusted by the degree of decompression of the outer peripheral space.

[0168] After step S22 is completed, similarly to step S14, the dried support 11 is subjected to heat treatment, and the first precursor layer 71 remaining inside the support 11 is cured (step S23). Specifically, for example, the support 11 is heated to 90°C to 500°C using a dryer and held for 0.5 hours to 72 hours, thereby curing the first precursor layer 71. The curing of the first precursor layer 71 in step S23 can be carried out by other methods.

[0169] After step S23 is completed, similarly to step S15, a second precursor solution is applied to the support 11 from the inner side of the compartment 111 (i.e., the inner side 331 of the surface layer 33). As described above, the second precursor solution contains a second precursor of carbon intended to form the carbon film 12. The second precursor solution permeates into the support 11 from the surface layer 33 side. Thus, as... Figure 15B As shown, a second precursor layer 72 containing a second precursor is formed inside the support 11. Figure 15B In the text, the second precursor layer 72 is marked with parallel oblique lines that are different from those of the first precursor layer 71. Figure 15C (Same as above).

[0170] exist Figure 15B In the example shown, the radially outer end of the second precursor layer 72 contacts the radially inner end of the first precursor layer 71 within the intermediate layer 32 (i.e., radially outer of the interface 332 between the surface layer 33 and the intermediate layer 32). As described above, the first precursor layer 71 has been cured in step S23. Therefore, even if the second precursor solution comes into contact with the first precursor layer 71, there will be no substantial mixing of the second precursor solution toward the first precursor layer 71 or dissolution of the first precursor layer 71. It should be noted that, because the solvent of the second precursor solution is different from that of the first precursor solution, even if the first precursor layer 71 is not cured, there will be no substantial mixing of the second precursor solution toward the first precursor layer 71 or dissolution of the first precursor layer 71. In such cases, the curing of the first precursor layer 71 in step S23 may be omitted.

[0171] The support 11, with the second precursor layer 72 formed inside, is dried, for example, by means of air supply or a dryer. The drying of the support 11 is performed, for example, at room temperature (25°C) to 90°C for 5 to 120 minutes. The dried support 11 is then subjected to a heat treatment, which cures the second precursor layer 72 inside the support 11. This heat treatment is performed, for example, in a manner substantially similar to the heat treatment in step S23. Specifically, the support 11 is heated to 90°C to 500°C using a dryer and held for 0.5 hours to 72 hours, thereby curing the second precursor layer 72.

[0172] exist Figure 15B In the example shown, the second precursor layer 72 is formed over approximately the entire surface layer 33 and approximately the entire portion of the intermediate layer 32 that is radially inward of the first precursor layer 71. In other words, the radially inward end of the second precursor layer 72 is located at approximately the same position radially as the inner surface 331 of the surface layer 33, which is the interface between the surface layer 33 and the predetermined carbon film 12. Forming the carbon film 12 cannot be achieved by applying the second precursor solution and performing the aforementioned heat treatment only once. Figure 15B In the case of the second precursor layer 72 shown (i.e., when the radial thickness of the second precursor layer 72 is insufficient), it can be formed by repeatedly applying the second precursor solution and performing the heat treatment described above multiple times. Figure 15B The second precursor layer 72 is shown.

[0173] Next, a second precursor solution is applied again to the support 11 from the inner side of the compartment 111 (i.e., the inner side 331 of the surface layer 33). The second precursor solution adheres to the inner side 331 of the surface layer 33, where the second precursor layer 72 is formed. Thus, as... Figure 15C As shown, a thin film containing the second precursor, namely the second precursor film 73, is formed on the inner side 331 of the surface layer 33 (i.e., the surface of the support 11) (step S24). Figure 15C In the diagram, the second precursor membrane 73 is marked with the same parallel oblique line as the second precursor layer 72.

[0174] The support 11, to which the second precursor film 73 is disposed, is dried, for example, by means of air supply or a dryer. The drying of the support 11 is performed, for example, at room temperature (25°C) for 5 to 120 minutes. The dried support 11 is then subjected to a heat treatment, which cures the second precursor film 73 on the surface of the support 11. This heat treatment is performed, for example, in a manner substantially similar to the heat treatment performed on the second precursor layer 72. For example, the support 11 is heated to 90°C to 500°C and held for 0.5 hours to 72 hours, thereby curing the second precursor film 73.

[0175] If, during the formation of the second precursor film 73, applying the second precursor solution and performing the aforementioned heat treatment once is insufficient to achieve the desired film thickness, the film thickness can be formed by repeatedly applying the second precursor solution and performing the aforementioned heat treatment multiple times. Figure 15C The second precursor film 73 is shown. Alternatively, if the second precursor layer 72 and the second precursor film 73 can be formed by applying the second precursor solution and heating once, the above-mentioned drying and heating treatments are not performed between the formation of the second precursor layer 72 and the formation of the second precursor film 73.

[0176] After step S24 is completed, similarly to step S16, the support 11, on which the first precursor layer 71, the second precursor layer 72, and the second precursor film 73 are disposed, is subjected to a carbonization treatment. As a result, a carbon-rich layer 35 is formed from the first precursor layer 71 inside the support 11, and a low-carbon layer 36 is formed from the second precursor layer 72. Furthermore, a carbon film 12 is formed from the second precursor film 73 on the surface of the support 11. Consequently, a carbon film composite 1a having the carbon-rich layer 35, the low-carbon layer 36, and the carbon film 12 is obtained (step S25).

[0177] exist Figure 13 In the carbon film composite 1a shown, the carbon-rich layer 35 is generally disposed inside the intermediate layer 32, but is not limited thereto. For example, the carbon-rich layer 35 may also span the interface 322 between the intermediate layer 32 and the substrate 31 (i.e., include the interface 322) and be disposed in both the intermediate layer 32 and the substrate 31.

[0178] Alternatively, carbon-rich layer 35 can also be like... Figure 16 As shown in carbon film composite 1b, it is disposed only inside the substrate 31. In other words, the carbon-rich layer 35 is located on the opposite side of the surface of the support 11 (i.e., the inner side 331 of the surface layer 33) relative to the interface 322 between the intermediate layer 32 and the substrate 31. In carbon film composite 1b, the carbon-rich layer 35 is also located on the opposite side of the surface of the support 11 relative to the interface 332 between the surface layer 33 and the intermediate layer 32. Carbon film composite 1b can be manufactured in substantially the same manner as carbon film composite 1a by the manufacturing method shown in steps S21 to S25 above.

[0179] Next, referring to Tables 1 and 2, Examples 1-6 of carbon film composite 1, Example 7 of carbon film composite 1a, Example 8 of carbon film composite 1b, and Comparative Example 1 of carbon film composite will be described. Table 1 shows the conditions for manufacturing the carbon film composite. Table 2 shows the carbon content and performance of the carbon film composite.

[0180] [Table 1]

[0181]

[0182] [Table 2]

[0183]

[0184] The carbon film composites 1 of Examples 1-6 were prepared by the manufacturing method described in steps S11-S16 above. In Examples 1-6, the concentration of the first precursor applied to the first precursor solution of the support 11 in step S12 was different for each example. In Examples 1-6, the drying of the support 11 in steps S12, S13, and S15 was performed at room temperature (25°C) for 20 minutes. In Examples 1-6, the curing of the first precursor layer 71 in step S14, and the curing of the second precursor layer 72 and the second precursor film 73 in step S15, were performed by heating the support 11 to 200°C in an atmospheric atmosphere and holding it for 5 hours. Furthermore, the carbonization treatment in step S16 was performed by heating the support 11 to 850°C in a vacuum atmosphere and holding it for 5 hours. The carbon film 12 of Examples 1-6 had the same thickness, as did the low-carbon layer 36 of Examples 1-6. The carbon-rich layer 35 of Examples 1-6 also had the same thickness. In Examples 1 to 6, the carbon-rich layer 35 is located on the surface layer 33.

[0185] The carbon film composites 1a and 1b of Examples 7 and 8 were obtained by the manufacturing method described in steps S21 to S25 above. That is, in Examples 7 and 8, the depressurization in step S22 was performed, but the removal treatment liquid was not applied in step S13 as in Examples 1 to 6. On the other hand, in Examples 1 to 6, the depressurization in step S22 was not performed. In Examples 7 and 8, the drying of the support 11 in steps S22 and S24 was performed at room temperature (25°C) for 20 minutes. In Examples 7 and 8, the curing of the first precursor layer 71 in step S23 and the curing of the second precursor layer 72 and the second precursor film 73 in step S24 were performed by heating the support 11 to 200°C in an atmospheric atmosphere and holding it for 5 hours. In addition, the carbonization treatment in step S25 was performed by heating the support 11 to 850°C in a vacuum atmosphere and holding it for 5 hours. The thickness of the carbon film 12 of Examples 7 and 8 is the same as the thickness of the carbon film 12 of Examples 1 to 6. The thickness of the carbon-rich layer 35 in Examples 7 and 8 is the same as that in Examples 1 to 6. In Example 7, the carbon-rich layer 35 is located in the intermediate layer 32. In Example 8, the carbon-rich layer 35 is located in the substrate 31.

[0186] In Comparative Example 1, the application of the removal treatment liquid in step S13 of steps S11 to S16 and the application of the second precursor solution in step S15 were omitted. In Comparative Example 1, by repeatedly applying the first precursor solution to the support 11 and allowing it to solidify, the first precursor layer 71 was formed substantially throughout the interior of the surface layer 33, and a thin film formed by the first precursor solution, i.e., the first precursor film, was formed on the inner surface 331 of the surface layer 33 (i.e., on the surface of the support 11). Subsequently, the carbonization treatment in step S16 was performed, thereby preventing the formation of the aforementioned low-carbon layer 36 and carbon-rich layer 35. The carbon content inside the surface layer 33 was substantially the same as the carbon content in the carbon-rich layer 35 of Examples 1 to 6. In addition, the first precursor contained in the first precursor film was carbonized, thereby forming a carbon film 12. The thickness of the carbon film 12 in Comparative Example 1 was substantially the same as the thickness of the carbon film 12 in Examples 1 to 6 and Examples 7 and 8.

[0187] In Examples 1-6 and Comparative Example 1, the carbon content in the carbon film 12, low-carbon layer 36, and carbon-rich layer 35 was obtained using the method described above. For measuring the signal intensity when determining the mass concentration, a JXA-8500F FE-EPMA (manufactured by Nippon Electronics Co., Ltd.) was used, with an accelerating voltage of 5 kV, a field of view of 38 μm × 50 μm, and a magnification of 2000x. 100% pure carbon (C) was used as the standard sample. Furthermore, the thickness of the low-carbon layer 36, etc., required for determining the carbon content of the low-carbon layer 36, was also obtained using the method described above. For measuring the position of the interface 332 between the surface layer 33 and the intermediate layer 32, and the thickness of the carbon film 12 and the surface layer 33, an SEM (manufactured by Hitachi High Tech Co., Ltd.) was used, with an accelerating voltage of 15 kV, a field of view of 36 μm × 50 μm, and a magnification of 50 to 20000x. In Examples 7 and 8, the carbon content in the carbon film 12, low-carbon layer 36, and carbon-rich layer 35 was obtained in roughly the same way.

[0188] The separation coefficients and permeation fluxes in Table 2 are obtained using the separation device 2 described above (see reference 2). Figure 12The measurements were performed. Specifically, firstly, a mixture of water and ethanol was supplied to the carbon membrane composites 1 and 1a from the supply section 26 of the separation device 2. The liquid separated by pervaporation (PV) (i.e., the liquid that has permeated through the carbon membrane 12 and the support 11, hereinafter also referred to as "permeate") was recovered by the second recovery section 28. The mass ratio of water to ethanol in the mixture was 50:50, and the temperature of the mixture supplied from the supply section 26 was 50°C. In addition, the pressure on the second recovery section 28 side, i.e., the permeate side pressure, was 6.67 kPa (i.e., 50 Torr). Next, the mass and density of the permeate recovered by the second recovery section 28 were measured, and the mass ratio of water to ethanol in the permeate was determined. The density of the permeate was measured using a hydrometer. Furthermore, based on the mass of the permeate and the mass ratio of water to ethanol in the permeate, the separation coefficient of water relative to ethanol in the carbon membrane composite 1 and the water permeation flux (kg / m³) were determined. 2 h).

[0189] In Table 2, “AA” in the separation coefficient column indicates a separation coefficient of 200 or higher; “A” indicates a separation coefficient of 140 or higher but less than 200. Additionally, “B” in the separation coefficient column indicates a separation coefficient of 100 or higher but less than 140; “C” indicates a separation coefficient of 80 or higher but less than 100; and “D” indicates a separation coefficient of less than 80.

[0190] In Table 2, "AA" in the permeability column indicates that the permeability of the water is 1.3 kg / (m³). 2 h) or above; "A" indicates that the water permeability flux is 1.0 kg / (m³). 2 h) or more and less than 1.3 kg / (m 2 h). Additionally, "B" in the flux column indicates a water flux of 0.7 kg / (m³). 2 h) or more and less than 1.0 kg / (m 2 h); "C" indicates that the water permeation flux is 0.3 kg / (m²). 2 h) or more and less than 0.7 kg / (m 2 h); "D" indicates that the water permeability flux is less than 0.3 kg / (m²). 2 h).

[0191] In Table 2, "AA" in the strength column indicates that the strength of carbon film composites 1 and 1a is above 60 MPa, and "A" indicates that the strength of carbon film composites 1 and 1a is less than 60 MPa. The strength of carbon film composites 1 and 1a was measured according to "JIS R 1601:2008". A flat test piece with a length of 20 mm, a width of 20 mm, and a thickness of 1.5 mm was used for measurement. The test piece was cut from the partition wall of the compartment 111 forming the support 11. The test piece, viewed from above (i.e., along the thickness direction), contained the intermediate layer 32 on approximately the entire surface.

[0192] In Example 1, the concentration of the first precursor in the first precursor solution applied to the support 11 in step S12 is 7.5% by mass. The first precursor is a phenolic resin (BELPEARL (registered trademark) S899 manufactured by Air & Water Co., Ltd.), and the solvent of the first precursor solution is ethanol (manufactured by Amazake Chemical Industry Co., Ltd.). The first precursor solution is generated as follows: the first precursor and solvent are weighed and mixed to achieve the above-mentioned concentration, stirred at room temperature with a magnetic stirrer for 4 days, and then filtered using a 20 μm sieve.

[0193] In Example 1, the removal treatment liquid in step S13 was applied. The solvent of the removal treatment liquid was the same as that of the first precursor solution. The concentration of the second precursor in the second precursor solution applied to the support 11 in step S15 was 2% by mass. The second precursor was phenolic resin (BELPEARL (registered trademark) S899 manufactured by Air & Water Co., Ltd.), and the solvent of the second precursor solution was ethanol (manufactured by Amazake Chemical Industry Co., Ltd.). The second precursor solution was generated as follows: 12g of phenolic resin as the second precursor was mixed with 588g of ethanol as the solvent, stirred at room temperature with a magnetic stirrer for 4 days, and then filtered through a 20μm sieve.

[0194] In Example 1, as described above, the carbon-rich layer 35 is located in the surface layer 33. In Example 1, the value obtained by dividing the maximum carbon content in the carbon-rich layer 35 by the average carbon content in the low-carbon layer 36 (hereinafter also referred to as the "carbon content ratio (carbon-rich layer / low-carbon layer)") is 1.2. In other words, the maximum carbon content in the carbon-rich layer 35 is 1.2 times the average carbon content in the low-carbon layer 36. Furthermore, the value obtained by dividing the maximum carbon content in the carbon-rich layer 35 by the maximum carbon content in the carbon film 12 (hereinafter also referred to as the "carbon content ratio (carbon-rich layer / carbon film)") is 0.07. In other words, the maximum carbon content in the carbon-rich layer 35 is 0.07 times the maximum carbon content in the carbon film 12. In Example 1, the separation coefficient is "A", the transmission flux is "A", and the intensity is "A".

[0195] Example 2 was identical to Example 1, except that the concentration of the first precursor in the first precursor solution was 10% by mass. In Example 2, the carbon content ratio (carbon-rich layer / low-carbon layer) was 2.0. Additionally, the carbon content ratio (carbon-rich layer / carbon film) was 0.12. In Example 2, the separation coefficient was "A", the permeation flux was "A", and the intensity was "A".

[0196] Example 3 was identical to Example 1, except that the concentration of the first precursor in the first precursor solution was 5% by mass. In Example 3, the carbon content ratio (carbon-rich layer / low-carbon layer) was 1.1. Additionally, the carbon content ratio (carbon-rich layer / carbon film) was 0.06. In Example 3, the separation coefficient was "B", the permeation flux was "AA", and the intensity was "A".

[0197] Example 4 was identical to Example 1, except that the concentration of the first precursor in the first precursor solution was 12% by mass. In Example 4, the carbon content ratio (carbon-rich layer / low-carbon layer) was 3.6. Additionally, the carbon content ratio (carbon-rich layer / carbon film) was 0.21. In Example 4, the separation coefficient was "AA", the permeation flux was "B", and the intensity was "A".

[0198] Example 5 was identical to Example 1, except that the concentration of the first precursor in the first precursor solution was 14% by mass. In Example 5, the carbon content ratio (carbon-rich layer / low-carbon layer) was 4.4. Additionally, the carbon content ratio (carbon-rich layer / carbon film) was 0.26. In Example 5, the separation coefficient was "AA", the permeation flux was "C", and the intensity was "A".

[0199] Example 6 was identical to Example 1, except that the concentration of the first precursor in the first precursor solution was 3% by mass. In Example 6, the carbon content ratio (carbon-rich layer / low-carbon layer) was 1.05. Additionally, the carbon content ratio (carbon-rich layer / carbon film) was 0.06. In Example 6, the separation coefficient was "C", the permeation flux was "AA", and the intensity was "A".

[0200] Except that Example 7 is manufactured using the manufacturing method described in the second embodiment, rather than the manufacturing method described in the first embodiment, Example 1 is the same. In Example 7, the carbon-rich layer 35 is located in the intermediate layer 32. In Example 7, the carbon content ratio (carbon-rich layer / low-carbon layer) is 1.2. Furthermore, the carbon content ratio (carbon-rich layer / carbon film) is 0.07. In Example 7, the separation coefficient is "A", the permeation flux is "B", and the intensity is "AA".

[0201] Except that the carbon-rich layer 35 is located on the substrate 31, Example 8 is the same as Example 7. In Example 8, the carbon content ratio (carbon-rich layer / low-carbon layer) is 1.2. In addition, the carbon content ratio (carbon-rich layer / carbon film) is 0.07. In Example 8, the separation coefficient is "A", the transmission flux is "B", and the intensity is "AA".

[0202] As described above, in Comparative Example 1, no removal treatment liquid or second precursor solution was applied. The concentration of the first precursor in the first precursor solution of Comparative Example 1 was the same as in Example 1, which was 7.5% by mass. In Comparative Example 1, the separation coefficient was “A”, the permeation flux was “D”, and the intensity was “A”. Unlike Examples 1-8, in Comparative Example 1, carbon was present in approximately the entire region of the surface layer 33 in the thickness direction, with a carbon content approximately the same as that of the carbon-rich layer 35 in Examples 1-8. Therefore, it is considered that in Comparative Example 1, when water that has permeated from the carbon film 12 permeates through the support 11, the permeation flux of water is reduced because the carbon present in approximately the entire region of the surface layer 33 in contact with the carbon film 12 (i.e., carbon present in a relatively high carbon content continuously from the surface of the support 11) hinders permeation.

[0203] In contrast, in Examples 1-8, the carbon-rich layer 35 with a higher carbon content is positioned separately from the surface of the support 11 (i.e., the inner surface 331 of the surface layer 33). Therefore, when water that has permeated through the carbon film 12 permeates through the support 11, the permeation is suppressed due to the carbon in the surface layer 33. As a result, the permeation flux of Examples 1-8 is all above "C" (i.e., "AA", "A", "B" or "C").

[0204] Comparing Examples 4 and 5, it can be seen that in order to achieve a transmission flux of "B" or higher (i.e., "AA", "A" or "B"), the carbon content ratio (carbon-rich layer / low-carbon layer) is preferably 4.0 or less. Furthermore, the carbon content ratio (carbon-rich layer / carbon film) is preferably 0.25 or less.

[0205] Comparing Example 2 and Example 4, it can be seen that in order to achieve a transmission flux of "A" or higher (i.e., "AA" or "A"), the carbon content ratio (carbon-rich layer / low carbon layer) is preferably 2.0 or lower.

[0206] Comparing Example 3 and Example 6, it can be seen that in order to make the separation coefficient reach "B" or above (i.e., "AA", "A" or "B"), the carbon content ratio (carbon-rich layer / low carbon layer) is preferably 1.1 or above.

[0207] Comparing Example 1 and Example 3, it can be seen that in order to make the separation coefficient reach "A" or above (i.e., "AA" or "A"), the carbon content ratio (carbon-rich layer / low carbon layer) is preferably 1.2 or above.

[0208] Comparing Examples 1 with Examples 7 and 8, it can be seen that, compared with the case where the carbon-rich layer 35 is located in the surface layer 33, the carbon film composites 1a and 1b are strengthened by having the carbon-rich layer 35 located in the intermediate layer 32 or the substrate 31.

[0209] As explained above, carbon film composites 1, 1a, and 1b each have a porous support 11 and a carbon film 12 disposed on the surface of the support 11 (in the example above, the inner surface of compartment 111). A carbon-rich layer 35, with a higher carbon content than the surrounding area, is disposed inside the support 11. The carbon-rich layer 35 is positioned separately from the surface of the support 11.

[0210] By providing a carbon-rich layer 35 inside the support 11, the mixed substances are effectively separated not only within the carbon film 12 but also inside the support 11. Therefore, the separation coefficient of the carbon film composites 1, 1a, and 1b can be improved. Furthermore, in the carbon film composites 1, 1a, and 1b, a low-carbon layer 36 with a lower carbon content is provided between the surface of the support 11 and the carbon-rich layer 35 to prevent the high-carbon-content carbon-rich layer 35 from contacting the carbon film 12. Thus, when substances that have permeated from the carbon film 12 flow into the support 11 and permeate, the obstruction of permeation by the carbon-rich layer 35 can be suppressed. As a result, the decrease in permeation flux of the carbon film composites 1, 1a, and 1b can be suppressed. In other words, in the aforementioned carbon film composites 1, 1a, and 1b, the decrease in permeation flux can be suppressed and the separation coefficient improved.

[0211] Preferably, the maximum carbon content in the carbon-rich layer 35 is at least 1.1 times and less than 4.0 times the average carbon content in the region between the surface of the support 11 and the carbon-rich layer 35 (i.e., the low-carbon layer 36). In other words, the carbon content ratio (carbon-rich layer / low-carbon layer) is preferably at least 1.1 and less than 4.0. Thus, as described above, it is possible to effectively balance suppressing the decrease in permeation flux of the carbon film composites 1, 1a, and 1b with improving the separation coefficient.

[0212] More preferably, the maximum carbon content in the carbon-rich layer 35 is at least 1.2 times and less than 2.0 times the average carbon content in the region between the surface of the support 11 and the carbon-rich layer 35 (i.e., the low-carbon layer 36). In other words, the carbon content ratio (carbon-rich layer / low-carbon layer) is preferably at least 1.2 and less than 2.0. Thus, as described above, it is possible to further and better balance suppressing the decrease in permeation flux of the carbon film composites 1, 1a, and 1b with improving the separation coefficient.

[0213] Preferably, the maximum carbon content in the carbon-rich layer 35 is 0.05 times or more and 0.25 times or less than the maximum carbon content in the carbon film 12. In other words, the carbon content ratio (carbon-rich layer / carbon film) is preferably 0.05 or more and 0.25 or less. Thus, as described above, it is possible to better balance suppressing the decrease in permeation flux of carbon film composites 1, 1a, and 1b with improving the separation coefficient.

[0214] As described above, in the thickness direction perpendicular to the surface of the support 11, the thickness of the carbon-rich layer 35 is preferably 0.01 μm or more and 15 μm or less. By setting the thickness of the carbon-rich layer 35 to 0.01 μm or more, a preferred separation coefficient can be achieved for the carbon film composites 1, 1a, and 1b. Furthermore, by setting the thickness of the carbon-rich layer 35 to 15 μm or less, the decrease in permeation flux of the carbon film composites 1, 1a, and 1b can be effectively suppressed. Therefore, it is possible to effectively balance suppressing the decrease in permeation flux of the carbon film composites 1, 1a, and 1b with improving the separation coefficient.

[0215] As shown in the first embodiment, the support 11 preferably includes a first layer (i.e., surface layer 33) and a second layer (i.e., intermediate layer 32). The surface layer 33 extends from the surface of the support 11 (in the above example, the inner side of the compartment 111) toward the interior of the support 11. The intermediate layer 32 extends from the surface layer 33 toward the interior of the support 11. The average pore size of the intermediate layer 32 is larger than that of the surface layer 33. In addition, the carbon-rich layer 35 is preferably located closer to the surface side of the support 11 than the interface 332 between the surface layer 33 and the intermediate layer 32.

[0216] By setting the carbon-rich layer 35 on the surface layer 33 in this way, compared with the case where the carbon-rich layer 35 is set on the intermediate layer 32 with a larger average pore size, the separation of the mixed substances in the carbon-rich layer 35 can be performed much better. As a result, the separation coefficient of the carbon film composite 1 can be significantly improved. In addition, by setting the carbon-rich layer 35 closer to the surface of the support 11, the formation of the carbon-rich layer 35 can be facilitated.

[0217] As described in the first embodiment above, the carbon-rich layer 35 is more preferably in contact with the interface 332 between the surface layer 33 and the intermediate layer 32. This allows the thickness of the low-carbon layer 36—the region between the surface of the support 11 (i.e., the inner surface 331 of the surface layer 33) and the carbon-rich layer 35—to increase radially (i.e., radially about the central axis of the compartment 111). As a result, the decrease in permeation flux can be suppressed, and the separation coefficient can be further improved. Furthermore, during the manufacture of the carbon film composite 1, since the penetration of the first precursor solution is easily stopped at the interface 332 between the surface layer 33 and the intermediate layer 32, which have different average pore sizes, the formation of the carbon-rich layer 35 with a desired radial thickness becomes easier.

[0218] As shown in the first embodiment, in the thickness direction perpendicular to the surface of the support 11, the sum of the thickness from the surface of the support 11 to the carbon-rich layer 35 (i.e., the thickness of the low-carbon layer 36) and the thickness of the carbon-rich layer 35 is preferably 0.1 μm or more and 30 μm or less. By setting this total thickness to 0.1 μm or more, the thickness of the carbon-rich layer 35 can be increased to a certain extent. This achieves a preferred separation coefficient for the carbon film composite 1. Furthermore, by setting this total thickness to 30 μm or less, excessive distance in the thickness direction between the carbon film 12 and the carbon-rich layer 35, as well as excessive thickness of the carbon-rich layer 35, can be suppressed. This effectively suppresses the decrease in the permeation flux of the carbon film composite 1. Therefore, both suppressing the decrease in the permeation flux of the carbon film composite 1 and improving the separation coefficient can be effectively balanced.

[0219] As shown in the first embodiment, in the thickness direction perpendicular to the surface of the support 11, the thickness from the surface of the support 11 to the carbon-rich layer 35 (i.e., the thickness of the low-carbon layer 36) is preferably 1.0 times or more and 20.0 times or less of the thickness of the carbon-rich layer 35. By setting the thickness of the low-carbon layer 36 to 1.0 times or more of the thickness of the carbon-rich layer 35, the distance in the thickness direction between the carbon film 12 and the carbon-rich layer 35 can be increased to a certain extent. This effectively suppresses the decrease in the permeation flux of the carbon film composite 1. Furthermore, by setting the thickness of the low-carbon layer 36 to 20.0 times or less of the thickness of the carbon-rich layer 35, excessive distance in the thickness direction between the carbon film 12 and the carbon-rich layer 35 can be suppressed. This achieves a preferred separation coefficient for the carbon film composite 1. Therefore, it is possible to effectively balance suppressing the decrease in the permeation flux of the carbon film composite 1 with improving the separation coefficient.

[0220] The manufacturing method of the carbon film composite 1 according to the first embodiment includes the following steps: applying a first precursor solution containing a first precursor to the surface of a porous support 11 (in the above example, the inner side of the compartment 111) and allowing it to penetrate, thereby forming a first precursor layer 71 containing the first precursor inside the support 11 (step S12); removing a portion of the first precursor layer 71 from the surface of the support 11 (step S13); applying a second precursor solution containing a second precursor to the surface of the support 11. The solution is used to form a second precursor layer 72 containing the second precursor inside the support 11, and a second precursor film 73 containing the second precursor is formed on the surface of the support 11 (step S15); and the first precursor layer 71, the second precursor layer 72 and the second precursor film 73 are carbonized to form a carbon film 12 on the surface of the support 11, while a carbon-rich layer 35 with a higher carbon content than the surrounding parts is formed inside the support 11 at a position separated from the surface of the support 11 (step S16).

[0221] Therefore, it is possible to manufacture a carbon film composite 1 having a carbon-rich layer 35 that is separated from the surface of the support 11. In this carbon film composite 1, the decrease in permeation flux can be suppressed and the separation coefficient can be improved as described above.

[0222] The manufacturing method of the carbon film composite 1 according to the first embodiment preferably includes a step (step S14) between steps S13 and S15, in which the first precursor layer 71 remaining inside the support 11 is cured. As a result, when the second precursor solution comes into contact with the first precursor layer 71, the mixing of the second precursor solution toward the first precursor layer 71 and the dissolution of the first precursor layer 71 can be effectively suppressed.

[0223] As shown in the second embodiment, the support 11 preferably comprises a first layer (i.e., surface layer 33) and a second layer (i.e., intermediate layer 32). The surface layer 33 extends from the surface of the support 11 (in the example above, the inner side of the compartment 111) toward the interior of the support 11. The intermediate layer 32 extends from the surface layer 33 toward the interior of the support 11. The average pore size of the intermediate layer 32 is larger than that of the surface layer 33. In addition, the carbon-rich layer 35 is preferably located on the opposite side of the surface of the support 11 relative to the interface 332 between the surface layer 33 and the intermediate layer 32.

[0224] In the carbon film composites 1a and 1b, a carbon-rich layer 35 is disposed in the intermediate layer 32 and / or the substrate 31. The average particle size of the aggregate particles in the intermediate layer 32 and the substrate 31 is larger than that in the surface layer 33, resulting in lower adhesion between the aggregate particles. The carbon-rich layer 35 enables good adhesion between the aggregate particles in the intermediate layer 32 and / or the substrate 31, thereby increasing the strength of the intermediate layer 32 and / or the substrate 31. Consequently, the strength of the carbon film composites 1a and 1b is increased.

[0225] As shown in the second embodiment, in the thickness direction perpendicular to the surface of the support 11, the sum of the thickness from the surface of the support 11 to the carbon-rich layer 35 (i.e., the thickness of the low-carbon layer 36) and the thickness of the carbon-rich layer 35 is preferably 1 μm or more and 1000 μm or less. By setting this total thickness to 1 μm or more, the thickness of the carbon-rich layer 35 can be increased to a certain extent. As a result, a preferred separation coefficient of the carbon film composites 1a and 1b can be achieved, and the strength of the intermediate layer 32 is significantly increased. In addition, by setting this total thickness to 1000 μm or less, excessive distance in the thickness direction between the carbon film 12 and the carbon-rich layer 35 and excessive thickness of the carbon-rich layer 35 can be suppressed. As a result, the decrease in the permeation flux of the carbon film composites 1a and 1b can be effectively suppressed. Therefore, it is possible to effectively suppress the decrease in the permeation flux of the carbon film composites 1a and 1b, improve the separation coefficient, and improve the strength of the intermediate layer 32.

[0226] The manufacturing method of the carbon film composites 1a and 1b according to the second embodiment includes the following steps: applying a first precursor solution containing a first precursor from the surface side (in the above example, the inner side of the compartment 111) of the porous support 11, while simultaneously depressurizing the side of the support 11 opposite to the surface, so that the first precursor solution penetrates into the support 11, forming a first precursor layer 71 containing the first precursor inside the support 11 (step S22); applying a first precursor layer 71 containing a second precursor from the surface side of the support 11. A second precursor solution is formed inside the support 11 to form a second precursor layer 72 containing the second precursor, and a second precursor film 73 containing the second precursor is formed on the surface of the support 11 (step S24); and the first precursor layer 71, the second precursor layer 72 and the second precursor film 73 are carbonized to form a carbon film 12 on the surface of the support 11, while a carbon-rich layer 35 with a higher carbon content than the surrounding area is formed inside the support 11 at a position separated from the surface of the support 11 (step S25).

[0227] Therefore, carbon film composites 1a and 1b having a carbon-rich layer 35 separated from the surface of the support 11 can be well manufactured. In these carbon film composites 1a and 1b, the decrease in permeation flux can be suppressed and the separation coefficient can be improved as described above. In addition, the strength of the intermediate layer 32 can also be increased.

[0228] The manufacturing method of the carbon film composites 1a and 1b according to the second embodiment preferably includes a step of curing the first precursor layer 71 between steps S22 and S24 (step S23). As a result, when the second precursor solution comes into contact with the first precursor layer 71, the mixing of the second precursor solution toward the first precursor layer 71 and the dissolution of the first precursor layer 71 can be effectively suppressed.

[0229] Various modifications can be made to the manufacturing methods of the carbon film composites 1, 1a, 1b and 1, 1a, 1b described above.

[0230] For example, the carbon-rich layer 35 can also be simultaneously disposed in both the surface layer 33 and the intermediate layer 32, spanning the interface 332 (i.e., including the interface 332). In this case, the maximum carbon content in the carbon-rich layer 35 (i.e., Figure 6A The boundaries of regions 64 and 65 in the text Figure 7A Area 65a in Figure 8A The boundaries of regions 64b and 65b in the text, and Figure 9AThe boundary between regions 64c and 65c in the carbon-rich layer 35 can be located, for example, in the surface layer 33, in the intermediate layer 32, or at the interface 332 between the surface layer 33 and the intermediate layer 32. Furthermore, the interface 332 between the surface layer 33 and the intermediate layer 32 can, for example, be located in the region of the carbon-rich layer 35 where the carbon content decreases from the maximum carbon content (i.e., Figure 6A Area 65 in Figure 7A Region 66a in Figure 8A Area 65b and Figure 9A Region 65c in the middle.

[0231] The thickness of the carbon-rich layer 35 can be less than 0.01 μm or more than 15 μm.

[0232] The maximum carbon content in the carbon-rich layer 35 can be less than 0.05 times or more than 0.25 times the maximum carbon content in the carbon film 12.

[0233] The maximum carbon content in the carbon-rich layer 35 can be more than 1.0 times the average carbon content in the low-carbon layer 36, but can be less than 1.2 times or less than 1.1 times. In addition, the maximum carbon content in the carbon-rich layer 35 can be more than 2.0 times or more than 4.0 times the average carbon content in the low-carbon layer 36.

[0234] In the carbon film composite 1, the thickness of the low-carbon layer 36 can be less than 1.0 times or more than 20.0 times the thickness of the carbon-rich layer 35.

[0235] In the carbon film composite 1, the sum of the thickness of the low-carbon layer 36 and the thickness of the carbon-rich layer 35 can be less than 0.1 μm or more than 30 μm.

[0236] In carbon film composites 1a and 1b, the sum of the thickness of the low-carbon layer 36 and the thickness of the carbon-rich layer 35 can be less than 1 μm or more than 1000 μm.

[0237] In carbon film composites 1, 1a, and 1b, the support 11 (i.e., the substrate 31, the intermediate layer 32, and the surface layer 33) does not necessarily need to be formed of ceramic; for example, it can also be formed of other materials such as metal.

[0238] In the support 11 of carbon film composites 1, 1a, and 1b, either the surface layer 33 or the intermediate layer 32 may be omitted, or both the surface layer 33 and the intermediate layer 32 may be omitted simultaneously. When both the surface layer 33 and the intermediate layer 32 are omitted, the substrate 31 functions solely as the support 11, and the carbon film 12 is directly disposed on the surface of the substrate 31. Alternatively, in carbon film composites 1, 1a, and 1b, in addition to the surface layer 33 and the intermediate layer 32, other layers with an average pore size smaller than that of the substrate 31 may be directly or indirectly disposed on the substrate 31. These other layers are laminated together with the surface layer 33 and the intermediate layer 32 on the substrate 31.

[0239] The local removal of the first precursor layer 71 in step S13 above does not necessarily need to be carried out by applying a removal treatment liquid; it can also be carried out by other methods.

[0240] The manufacturing method of carbon film composites 1, 1a, and 1b is not limited to the above-mentioned method, and carbon film composites 1, 1a, and 1b can also be manufactured by other manufacturing methods.

[0241] As long as they do not contradict each other, the structures in the above-described implementation methods and their variations can be appropriately combined.

[0242] The invention has been described in detail, but the above description is merely illustrative and does not constitute a limitation. Therefore, it can be said that various modifications or solutions can be adopted without departing from the scope of the invention.

[0243] Industrial availability

[0244] This invention can be used for the separation of various substances utilizing carbon membranes, etc.

[0245] Explanation of reference numerals in the attached figures

[0246] 1, 1a, 1b Carbon film composite

[0247] 11 Support body

[0248] 12 Carbon film

[0249] 32 Intermediate Layer

[0250] 33 Surface layer

[0251] 35 Carbon-rich layer

[0252] 36 Low-carbon layer

[0253] 71 First precursor layer

[0254] 72 Second precursor layer

[0255] 73 Second precursor membrane

[0256] Interfaces 332, 352, and 351

[0257] 331 Inner surface

[0258] Steps S11 to S16

Claims

1. A carbon film composite, comprising: Porous supports, and A carbon film is disposed on the surface of the support. A carbon-rich layer is provided inside the support body, which is located at a position separated from the surface of the support body and has a higher carbon content than the surrounding parts.

2. The carbon film composite according to claim 1, wherein, The support body comprises: A first layer, extending from the surface of the support towards the interior of the support; and The second layer extends from the first layer toward the interior of the support and has a larger average pore size than the first layer. The carbon-rich layer is located closer to the surface side of the support than the interface between the first layer and the second layer.

3. The carbon film composite according to claim 2, wherein, The carbon-rich layer is in contact with the interface between the first layer and the second layer.

4. The carbon film composite according to claim 2, wherein, In the thickness direction perpendicular to the surface of the support, the sum of the thickness from the surface of the support to the thickness of the carbon-rich layer and the thickness of the carbon-rich layer is more than 0.1 μm and less than 30 μm.

5. The carbon film composite according to claim 2, wherein, In the thickness direction perpendicular to the surface of the support, the thickness from the surface of the support to the carbon-rich layer is more than 1.0 times and less than 20.0 times the thickness of the carbon-rich layer.

6. The carbon film composite according to claim 1, wherein, The support body comprises: A first layer, extending from the surface of the support towards the interior of the support; and The second layer extends from the first layer toward the interior of the support and has a larger average pore size than the first layer. The carbon-rich layer is located on the opposite side of the surface of the support relative to the interface between the first layer and the second layer.

7. The carbon film composite according to claim 6, wherein, In the thickness direction perpendicular to the surface of the support, the sum of the thickness from the surface of the support to the thickness of the carbon-rich layer and the thickness of the carbon-rich layer is more than 1 μm and less than 1000 μm.

8. The carbon film composite according to any one of claims 1 to 7, wherein, The maximum carbon content in the carbon-rich layer is more than 1.1 times and less than 4.0 times the average carbon content in the region between the surface of the support and the carbon-rich layer.

9. The carbon film composite according to claim 8, wherein, The maximum carbon content in the carbon-rich layer is more than 1.2 times and less than 2.0 times the average carbon content in the region between the surface of the support and the carbon-rich layer.

10. The carbon film composite according to any one of claims 1 to 7, wherein, The maximum carbon content in the carbon-rich layer is more than 0.05 times and less than 0.25 times the maximum carbon content in the carbon film.

11. The carbon film composite according to any one of claims 1 to 7, wherein, In the thickness direction perpendicular to the surface of the support, the thickness of the carbon-rich layer is 0.01 μm or more and 15 μm or less.

12. A method for manufacturing a carbon film composite, comprising the following steps: a) Apply a first precursor solution containing the first precursor from the surface side of the porous support and allow it to penetrate, thereby forming a first precursor layer containing the first precursor inside the support; b) Remove a portion of the first precursor layer from the surface side of the support; c) Apply a second precursor solution containing the second precursor from the surface side of the support to form a second precursor layer containing the second precursor inside the support and to form a film containing the second precursor, i.e., a second precursor film, on the surface of the support. as well as d) By carbonizing the first precursor layer, the second precursor layer, and the second precursor film, a carbon film is formed on the surface of the support, while a carbon-rich layer is formed inside the support, the carbon-rich layer being disposed at a position separated from the surface of the support and having a higher carbon content than the surrounding area.

13. The method for manufacturing the carbon film composite according to claim 12, wherein, Between step b) and step c), there is also a step of curing the first precursor layer remaining inside the support.

14. A method for manufacturing a carbon film composite, comprising the following steps: a) Apply a first precursor solution containing a first precursor to the surface side of a porous support, while simultaneously depressurizing the side of the support opposite to the surface, so that the first precursor solution penetrates into the support, thereby forming a first precursor layer containing the first precursor inside the support. b) Apply a second precursor solution containing the second precursor from the surface side of the support to form a second precursor layer containing the second precursor inside the support and to form a film containing the second precursor, i.e., a second precursor film, on the surface of the support. as well as c) By carbonizing the first precursor layer, the second precursor layer, and the second precursor film, a carbon film is formed on the surface of the support, while a carbon-rich layer is formed inside the support, the carbon-rich layer being disposed at a position separated from the surface of the support and having a higher carbon content than the surrounding area.

15. The method for manufacturing the carbon film composite according to claim 14, wherein, Between step a) and step b), there is also a step of curing the first precursor layer.

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