JP6417355B2 - Monolith type separation membrane structure - Google Patents

Description

  The present invention relates to a monolithic separation membrane structure.

  A monolithic separation membrane structure including a support having a plurality of filtration cells and a separation membrane formed on the inner surface of each filtration cell is known. In the monolith type separation membrane structure, a component that can permeate the separation membrane (hereinafter referred to as “permeation component”) out of the mixed fluid flowing through each filtration cell is caused to flow out from the outflow surface (eg, side surface) of the support. Can do.

  Conventionally, in the monolith type separation membrane structure, various methods for making the thicknesses of all the separation membranes uniform have been proposed (see, for example, Patent Document 1).

JP 2000-288324 A

  By the way, the pressure loss of the permeable component that passes through the separation membrane and passes through the inside of the support is smaller as the filtration cell is closer to the outflow surface. The closer you are, the more. Therefore, the membrane life of the separation membrane provided in the filtration cell close to the outflow surface tends to be shorter than the membrane life of the separation membrane provided in the filtration cell far from the outflow surface. Therefore, there is a demand to reduce the difference in permeation amount of permeation components in each separation membrane regardless of the distance between the filtration cell and the outflow surface.

  This invention is made | formed in view of the above-mentioned situation, and it aims at providing the monolith type | mold separation membrane structure which can reduce the permeation | transmission amount difference of the permeable component in each separation membrane.

  The monolith type separation membrane structure according to the present invention separates the permeated component from the mixed fluid. The monolithic separation membrane structure includes a support, a first separation membrane, and a second separation membrane. The support has first and second filtration cells that are continuous from the first end surface to the second end surface, and an outflow surface from which a permeated component flows out. The first separation membrane is formed on the inner surface of the first filtration cell. The second separation membrane is formed on the inner surface of the second filtration cell. The first filtration cell is closer to the outflow surface than the second filtration cell. The first film thickness of the first separation membrane is thicker than the second film thickness of the second separation film.

  ADVANTAGE OF THE INVENTION According to this invention, the monolith type separation membrane structure which can reduce the permeation | transmission amount difference of the permeation | transmission component in each separation membrane can be provided.

Perspective view of monolithic separation membrane structure Plan view of monolithic separation membrane structure AA sectional view of FIG. Partial enlarged view of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic, and the ratio of each dimension may be different from the actual one.

(Configuration of monolith type separation membrane structure 10)
FIG. 1 is a perspective view of a monolith type separation membrane structure 10. FIG. 2 is a plan view of the monolithic separation membrane structure 10. FIG. 3 is a cross-sectional view taken along the line AA of FIG. The monolithic separation membrane structure 10 includes a support 20, a first seal portion 21, a second seal portion 22, and a separation membrane 23.

  The support 20 is formed in a monolith shape having a plurality of filtration cells CL for circulating a mixed fluid (mixed liquid or mixed gas) to be filtered. The “monolith shape” means a shape having a plurality of communication holes formed in the longitudinal direction, and is a concept including a honeycomb shape.

  Although the length in particular of the support body 20 is not restrict | limited, For example, it can be 150 mm-2000 mm. Although the diameter in particular of the support body 20 is not restrict | limited, For example, it can be set as 30 mm-220 mm.

  The support 20 has a first end surface S1, a second end surface S2, and a side surface S3. The first end surface S1 is provided opposite to the second end surface S2. The side surface S3 is continuous with the first end surface S1 and the second end surface S2. Each filtration cell CL penetrates the support 20 from the first end surface S1 to the second end surface S2. Each filtration cell CL extends in the longitudinal direction of the support 20. In the present embodiment, the cross section of each filtration cell CL is circular, but is not limited to a circular shape, and may be a polygon more than a triangle. The side surface S3 is an example of an “outflow surface” in which a component that permeates the separation membrane 23 (hereinafter referred to as “permeation component”) out of the mixed fluid that flows to each filtration cell CL flows out from the support 20 to the outside. is there.

  In this embodiment, the support body 20 has the base material 20a, the intermediate | middle layer 20b, and the surface layer 20c, as shown in FIG.

  The base material 20a is made of a porous material. As the porous material, for example, a ceramic sintered body, metal, organic polymer, glass, or carbon can be used. Examples of the ceramic sintered body include alumina, silica, mullite, zirconia, titania, yttria, silicon nitride, and silicon carbide. Examples of the metal include aluminum, iron, bronze, silver, and stainless steel. Examples of the organic polymer include polyethylene, polypropylene, polytetrafluoroethylene, polysulfone, and polyimide.

  The base material 20a may contain an inorganic binder. As the inorganic binder, at least one of titania, mullite, easily sinterable alumina, silica, glass frit, clay mineral, and easily sinterable cordierite can be used.

  The average pore diameter of the base material 20a can be set to, for example, 5 μm to 25 μm. The average pore diameter of the substrate 20a can be measured with a mercury porosimeter. The porosity of the base material 20a can be set to 25% to 50%, for example. The average particle diameter of the porous material constituting the substrate 20a can be set to 5 μm to 100 μm, for example. In the present embodiment, the “average particle diameter” is a value obtained by arithmetically averaging the maximum diameters of 30 measurement target particles measured by cross-sectional microstructure observation using SEM (Scanning Electron Microscope).

  The intermediate layer 20b is formed on the base material 20a. The intermediate layer 20b can be composed of the porous material that can be used for the base material 20a. The average pore diameter of the intermediate layer 20b may be smaller than the average pore diameter of the substrate 20a, and may be, for example, 0.005 μm to 5 μm. The average pore diameter of the intermediate layer 20b can be measured with a palm porometer. The porosity of the intermediate layer 20b can be set to, for example, 20% to 60%. The thickness of the intermediate layer 20b can be set to 1 μm to 300 μm, for example.

  The surface layer 20c is formed on the intermediate layer 20b. The surface layer 20c can be comprised with the said porous material which can be used for the base material 20a. The average pore diameter of the surface layer 20c may be smaller than the average pore diameter of the intermediate layer 20b, and may be, for example, 0.001 μm to 2 μm. The average pore diameter of the surface layer 20c can be measured with a palm porometer. The porosity of the surface layer 20c can be set to, for example, 20% to 60%. The thickness of the surface layer 20c can be set to 1 μm to 50 μm, for example.

  The first seal portion 21 covers substantially the entire first end surface S1 and part of the side surface S3. The first seal portion 21 suppresses the mixed fluid from infiltrating the first end surface S <b> 1 of the support 20. As a material constituting the first seal portion 21, glass, metal, or the like can be used, and glass is suitable in consideration of consistency with the thermal expansion coefficient of the support 20.

  The second seal portion 22 covers substantially the entire second end surface S2 and a part of the side surface S3. The second seal portion 22 suppresses the mixed fluid from infiltrating the second end surface S <b> 2 of the support 20. As a material constituting the second seal portion 22, glass, metal, or the like can be used, and glass is suitable in consideration of consistency with the thermal expansion coefficient of the support 20.

  The separation membrane 23 is formed on the inner surface of each filtration cell CL formed on the support 20. The separation membrane 23 is formed in a cylindrical shape. The thickness of the separation membrane 23 can be arbitrarily set depending on the material type constituting the separation membrane 23. The separation membrane 23 may have micro-sized pores or nano-sized pores.

  As a material constituting the separation membrane 23, an inorganic material, a metal, or the like can be used. Examples of the inorganic material for the separation membrane 23 include ceramic sintered bodies, zeolite, carbon, and silica. Examples of the ceramic sintered body constituting the separation membrane 23 include alumina, silica, mullite, zirconia, titania, yttria, silicon nitride, silicon carbide, and the like. The ceramic sintered body may contain an inorganic binder. As the inorganic binder, at least one of titania, mullite, easily sinterable alumina, silica, glass frit, clay mineral, and easily sinterable cordierite can be used. The crystal structure of the zeolite constituting the separation membrane 23 is not particularly limited, and for example, LTA, MFI, MOR, FER, FAU, DDR, CHA, BEA and the like can be used. When the separation membrane 23 is a DDR type zeolite membrane, it can be suitably used as a gas separation membrane for selectively separating carbon dioxide. Examples of the metal material constituting the separation membrane 23 include palladium.

(Thickness of each separation membrane 23)
Next, the thickness of each separation membrane 23 will be described. FIG. 4 is a partially enlarged view of FIG. In the following description, as shown in FIG. 4, the filtration cell CL adjacent to the side surface S3 which is an example of the outflow surface is referred to as “first filtration cell CL1”, and the filtration cell CL adjacent to the inside of the first filtration cell CL1. Is referred to as “second filtration cell CL2”. Further, the separation membrane 23 formed on the inner surface of the first filtration cell CL1 is referred to as “first separation membrane 231”, and the separation membrane 23 formed on the inner surface of the second filtration cell CL2 is referred to as “second separation membrane 232”. ".

  The first film thickness t1 of the first separation film 231 is thicker than the second film thickness t2 of the second separation film 232. Each of the first film thickness t1 and the second film thickness t2 is not particularly limited, and can be arbitrarily set depending on the material type constituting the separation film 23. Each of the first film thickness t1 and the second film thickness t2 is preferably 10 μm or less, and more preferably 5 μm or less, in consideration of securing the transmission amount of the transmission component contained in the mixed fluid. The ratio (t2 / t1) of the second film thickness t2 to the first film thickness t1 is not particularly limited and can be 0.83 or less. That is, the first film thickness t1 can be 1.2 times or more the second film thickness t2. The first film thickness t1 is preferably 1.5 times or more, more preferably 2.0 times or more of the second film thickness t2.

  Here, since the first filtration cell CL1 is closer to the side surface S3 that is the outflow surface of the permeated component than the second filtration cell CL2, the first filtration cell CL1 passes through the first filtration cell CL1 and passes through the inside of the support 20. The pressure loss of the component is smaller than the pressure loss of the permeated component that passes through the inside of the support 20 through the second filtration cell CL2. Therefore, the permeation amount of the permeation component that permeates the first separation membrane 231 tends to be larger than the permeation amount of the permeation component that permeates the second separation membrane 232. Therefore, in the present embodiment, by making the film thickness t1 of the first separation membrane 231 thicker than the second film thickness t2 of the second separation membrane 232, the amount of transmission of the permeable component that passes through the first separation membrane 231 is intentionally made. It has been reduced. As a result, the difference in permeation amount of the permeation component between the first separation membrane 231 and the second separation membrane 232 is reduced, so that the difference in membrane lifetime between the first separation membrane 231 and the second separation membrane 232 can be suppressed.

  In the present embodiment, the film thickness of the separation membrane 23 is a film thickness measured at a position 20 mm inside from one end of the filtration cell CL and a film measured at a position 20 mm inside from the other end of the filtration cell CL. It means the arithmetic average value of the thickness and the thickness measured at the center of the filtration cell CL.

  The first interval s1 between the first separation membrane 231 and the side surface S3 of the support 20 is shorter than the second interval s2 between the second separation membrane 232 and the side surface S3 of the support 20. Further, as described above, the first film thickness t1 of the first separation film 231 is thicker than the second film thickness t2 of the second separation film 232. The following relational expression (1) is preferably established among the first interval s1, the second interval s2, the first film thickness t1, and the second film thickness t2.

    A * t1 + B * s1 = A * t2 + B * s2 (1)

  Further, the following relational expression (2) is derived from the relational expression (1).

    A (t1-t2) = B (s2-s1) (2)

  Further, the following relational expression (3) is derived from the relational expression (2).

    A / B = (s2-s1) / (t1-t2) (3)

In the relational expression (1), “A” is the resistance coefficient of the separation membrane 23 (the first separation membrane 231 and the second separation membrane 232). The resistance coefficient A of the separation membrane 23 is the reciprocal of the permeation amount of water per unit time in the separation membrane 23. The permeation amount of water per unit time in the separation membrane 23 is such that water (water temperature 25 ° C.) is supplied to each filtration cell CL of the monolith type separation membrane structure 10, and the difference between the inlet pressure and the outlet pressure of the separation membrane 23. It can be obtained by converting the amount of water permeation per unit time when the pressure is 1 kgf / m ² .

  Note that the value of the resistance coefficient A of the separation membrane 23 may vary depending on the diffusion mode of the permeable component in the separation membrane 23. It has been found that the diffusion mode of the permeation component generally changes to bulk diffusion, Knudsen diffusion, surface diffusion, activation diffusion, and solid phase diffusion in order as the pore diameter of the separation membrane 23 decreases.

In the relational expression (1), “B” is the resistance coefficient of the support 20. The resistance coefficient B of the support 20 is the reciprocal of the permeation amount of water per unit time in the support 20. The permeation amount of water per unit time in the support 20 is determined by removing water (water temperature 25 ° C.) into each filtration cell CL after removing the separation membrane 23 formed in each filtration cell CL of the monolithic separation membrane structure 10. This is obtained by converting the permeation amount of water when the differential pressure between the inlet pressure and the outlet pressure of the support 20 is 1 kgf / m ² . Although the removal method in particular of the separation membrane 23 is not restrict | limited, For example, the method of scraping off using tools, such as a drill, can be used.

  Note that the value of the resistance coefficient B of the support 20 can vary depending on the diffusion mode of the transmissive component in the support 20. It has been found that the diffusion mode of the permeation component generally changes to bulk diffusion, Knudsen diffusion, surface diffusion, activation diffusion, and solid phase diffusion in order as the pore diameter of the separation membrane 23 decreases.

  When the above relational expression (1) is established among the first interval s1, the second interval s2, the first film thickness t1, and the second film thickness t2, the transmission component of the first separation film 231 and the second separation film 232 Since the permeation amount can be made equal, the difference in membrane lifetime between the first separation membrane 231 and the second separation membrane 232 can be further suppressed.

  As described above, the mutual relationship between the film thickness of the first and second separation membranes 231 and 232 and the distance from the side surface S3 has been described, but the above-described mutual relationship is established among all the separation membranes 23. To do.

(Method for producing separation membrane structure)
A method for manufacturing the monolithic separation membrane structure 10 will be described.

(1) Formation of Support 20 First, a molded body of the base 20a is formed by molding the raw material of the base 20a into a desired shape using an extrusion molding method, a press molding method, a casting molding method, or the like. Next, the molded body of the base material 20a is fired (for example, 900 ° C. to 1450 ° C.) to form the base material 20a. The base material 20a has a plurality of through holes for forming a plurality of filtration cells CL.

  Next, an intermediate layer slurry is prepared using a ceramic raw material having a desired particle diameter, and the intermediate layer slurry is adhered to the inner surface of each through hole of the substrate 20a by a falling film formation method or a filtration film formation method. . As a result, a formed body of the intermediate layer 20b is formed on the inner surface of the substrate 20a. Subsequently, the molded body of the intermediate layer 20b is fired (for example, 900 ° C. to 1450 ° C.) to form the intermediate layer 20b.

  Next, a surface layer slurry is prepared using a ceramic raw material having a desired particle diameter, and the surface layer slurry is adhered to the inner surface of the intermediate layer 20b by a falling film forming method or a filtration film forming method. Thereby, a molded body of the surface layer 20c is formed on the inner surface of the intermediate layer 20b. Subsequently, the molded body of the surface layer 20c is fired (for example, 300 ° C. to 1450 ° C.) to form the surface layer 20c. Thus, the support 20 having a plurality of filtration cells CL is completed.

(2) Formation of separation membrane 23 The separation membrane 23 is formed on the inner surface of the surface layer 20c. The separation membrane 23 can be formed by a conventionally known method according to the type of membrane. Hereinafter, a method for forming each of the zeolite membrane, the silica membrane, and the carbon membrane will be sequentially described as an example of a method for forming the separation membrane 23.

-Zeolite membrane First, a seed crystal solution containing a zeolite seed crystal is applied to the inner surface of each filtration cell CL by a falling film forming method or a filtration film forming method.

  In the case of using the falling film forming method, the seed crystal solution is allowed to flow evenly through all the filtration cells CL, and then the filtration cell CL at a position close to the center of the support 20 (that is, the axis of the support 20). The inlet is closed with a resin cover or the like, and the seed crystal solution is allowed to flow again only to the filtration cell CL away from the center of the support 20. Thereby, a large amount and a large amount of zeolite seed crystals can be attached to the inner surface of the filtration cell CL near the side surface S3.

In the case of using the filtration film formation method, when the seed crystal solution is poured into all the filtration cells CL, the side surface S3 side is rapidly increased in negative pressure (for example, 2.5 × 10 ⁻³ MPa / S to 7.0). Usually negative pressure after raising × to ¹⁰ -3 MPa / S) (e.g., reduced to ^{6.5 × 10 -4 MPa / S~2.0 ×} 10 -3 MPa / S). Thereby, a large amount and a large amount of zeolite seed crystals can be attached to the inner surface of the filtration cell CL near the side surface S3.

  Next, the support 20 is immersed in a pressure resistant container containing a raw material solution in which at least one of a nitrogen adsorbing metal cation and a nitrogen adsorbing metal complex is added to a silica source, an alumina source, an organic template, an alkali source, and water.

  Next, the pressure-resistant container is put into a dryer, and a zeolite membrane is formed on the inner surface of each filtration cell CL by performing heat treatment (hydrothermal synthesis) at 100 to 200 ° C. for about 1 to 240 hours. As described above, since a large amount and a large amount of zeolite seed crystals are attached to the inner surface of the filtration cell CL near the side surface S3, as shown in FIG. 4, the first separation in the first filtration cell CL1 near the side surface S3. The film thickness of the film 231 is thicker than the film thickness of the second separation film 232 in the second filtration cell CL2 that is away from the side surface S3.

  Next, the support 20 on which the zeolite membrane is formed is washed and dried at 80 to 100 ° C. In addition, when an organic template is contained in a raw material solution, the support body 20 is put into an electric furnace, and the organic template is burned and removed by heating at 400 to 800 ° C. for about 1 to 200 hours in the atmosphere.

Silica film First, tetraethoxysilane is hydrolyzed in the presence of nitric acid to form a sol solution, and a precursor solution (silica sol solution) is prepared by diluting with ethanol or water.

  Next, the precursor solution is brought into contact with the inner surface of each filtration cell CL by a falling film formation method or a filtration film formation method.

  When using the falling film forming method, the precursor solution is allowed to flow evenly through all the filtration cells CL, and then the inlet of the filtration cell CL near the center of the support 20 is closed with a resin cover or the like. The precursor solution is allowed to flow again only to the filtration cell CL away from the center of the body 20. Thereby, the precursor solution can be thickly attached to the inner surface of the filtration cell CL close to the side surface S3.

When the filtration film forming method is used, when the precursor solution is poured into all the filtration cells CL, the side surface S3 side is rapidly increased in a negative pressure (for example, 2.5 × 10 ⁻³ MPa / S to 1.0 After raising the pressure to x10 ⁻² MPa / S, the pressure is reduced to a normal negative pressure (for example, 7.5 × 10 ⁻⁴ MPa / S to 3.5 × 10 ⁻³ MPa / S). Thereby, the precursor solution can be thickly attached to the inner surface of the filtration cell CL close to the side surface S3.

  Next, the temperature is raised to 400 to 700 ° C. at 100 ° C./hr and held for 1 hour, and then the temperature is lowered at 100 ° C./hr. A silica film is formed by repeating the above steps 3 to 5 times. As described above, since the precursor solution is thickly attached to the inner surface of the filtration cell CL near the side surface S3, as shown in FIG. 4, the first separation membrane 231 in the first filtration cell CL1 near the side surface S3. Is thicker than the thickness of the second separation membrane 232 in the second filtration cell CL2 away from the side surface S3.

-Carbon film First, a thermosetting resin such as an epoxy resin or a polyimide resin, a thermoplastic resin such as polyethylene, a cellulosic resin, or a precursor material thereof, at least one of a nitrogen adsorbing metal cation and a nitrogen adsorbing metal complex A precursor solution is prepared by dissolving in an organic solvent such as methanol, acetone, tetrahydrofuran, NMP, toluene, or water to which is added.

  Next, the precursor solution is brought into contact with the inner surface of each filtration cell CL by a falling film formation method or a filtration film formation method.

  When using the falling film forming method, the precursor solution is allowed to flow evenly through all the filtration cells CL, and then the inlet of the filtration cell CL near the center of the support 20 is closed with a resin cover or the like. The precursor solution is allowed to flow again only to the filtration cell CL away from the center of the body 20. Thereby, the precursor solution can be thickly attached to the inner surface of the filtration cell CL close to the side surface S3.

When the filtration film-forming method is used, when the precursor solution is poured into all the filtration cells CL, the side surface S3 side is suddenly exposed to a high negative pressure (for example, 2.5 × 10 ⁻³ MPa / S to 6.0). × ¹⁰ -3 MPa / S) usually is lowered to a negative pressure (e.g. ^{6.0 × 10 -4 MPa / S~1.6 ×} 10 -3 MPa / S) after increased to. Thereby, the precursor solution can be thickly attached to the inner surface of the filtration cell CL close to the side surface S3.

  Next, a carbon film is formed by performing a heat treatment (for example, 500 ° C. to 1000 ° C.) according to the type of resin contained in the precursor solution. As described above, since the precursor solution is thickly attached to the inner surface of the filtration cell CL near the side surface S3, as shown in FIG. 4, the first separation membrane 231 in the first filtration cell CL1 near the side surface S3. Is thicker than the thickness of the second separation membrane 232 in the second filtration cell CL2 away from the side surface S3.

(Other embodiments)
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention.

  In the above-described embodiment, the support 20 includes the base material 20a, the intermediate layer 20b, and the surface layer 20c. You don't have to. When the support 20 has only the base material 20a, the separation membrane 23 is formed on the inner surface of the base material 20a.

  In the above embodiment, the monolithic separation membrane structure 10 may include another functional membrane (for example, an adsorption membrane or a protective membrane) stacked on the inner surface of the separation membrane 23. As the functional film, an inorganic film such as a zeolite film, a carbon film, or a silica film, or an organic film such as a polyimide film or a silicone film can be used. Also in such a functional film, it is preferable that the correlation between the film thicknesses of the first and second separation films 231 and 232 and the distance from the side surface S3 is established.

  In the above embodiment, the mutual relationship between the thicknesses of the first and second separation membranes 231 and 232 and the distance from the side surface S3 is established among all the separation membranes 23. However, at least two separation membranes 23 are used. It is only necessary that the above-described mutual relationship is established. Even in this case, the difference in membrane life between the two separation membranes 23 can be suppressed.

  In the above-described embodiment, the side surface is described as an example of the “outflow surface” through which the permeation component flows out from the support 20, but the separation membrane structure is formed in parallel with the filtration cell and has both ends. When the portion has a “water collection cell” that is sealed, not only the side surface but also the inner surface of the water collection cell is an “outflow surface”. Further, in the case where the water collection cell is connected to the discharge channel opened to the side surface S3, not only the side surface and the inner surface of the water collection cell but also the inner surface of the discharge channel becomes the “outflow surface”. Details of such a separation membrane structure including a water collection cell and a discharge channel are described in, for example, International Publication No. 2014-050702.

  Examples of the present invention will be described below. However, the present invention is not limited to the examples described below.

(Production of sample Nos. 1 to 3)
First, 20 parts by mass of glass powder (inorganic binder) is added to 100 parts by mass of alumina powder (aggregate) having an average particle size of 100 μm, and water, a dispersant, and a thickener are added and mixed to knead. A clay was prepared. The obtained kneaded material was extruded to produce a monolith-shaped substrate. And the molded object of the base material was baked (1250 degreeC, 2 hours).

  Next, 14 parts by mass of titania powder was added to 100 parts by mass of alumina powder having an average particle size of 50 μm, and further, water, a dispersant, and a thickener were added and mixed to prepare a slurry for the intermediate layer. . Next, the intermediate layer slurry was adhered to the inner surface of the through-hole of the base material by a flow-down method to form an intermediate layer molded body. And it baked (1250 degreeC, 1 hour) with the electric furnace in air | atmosphere atmosphere, and formed the intermediate | middle layer.

  Next, 14 parts by mass of titania powder is added to 100 parts by mass of alumina powder having an average particle size of 0.6 μm, and further, water, a dispersant, and a thickener are added and mixed to prepare a slurry for the surface layer. did. Next, the surface layer molded body was formed by adhering the surface layer slurry to the inner surface of the intermediate layer by the flow-down method. And it baked (1250 degreeC, 1 hour) with the electric furnace in air | atmosphere atmosphere, and formed the surface layer.

  Thus, a monolithic support having a plurality of filtration cells was completed. The 1st space | interval s1 of the 1st filtration cell adjacent to the side surface of a support body among several filtration cells and a side surface was 2 mm. Moreover, the 2nd space | interval s2 of the 2nd filtration cell adjacent to the inner side of a 1st filtration cell and a side surface was 2.5 mm.

  Next, a precursor solution (titania sol solution) was prepared by diluting a sol solution obtained by hydrolyzing titanium alkoxide in the presence of nitric acid with ethanol. Next, a titania film formed body was formed by adhering a titania sol solution to the inner surface of each filtration cell by a flow-down method. At this time, by increasing the number of times the titania sol flowed down the filtration cell away from the center of the support, the thickness of the titania film molded body was increased as the filtration cell was closer to the side of the support.

  Next, the titania membrane was fired (400 ° C., 1 hour) to form a titania membrane as a separation membrane. As shown in Table 1, the first thickness t1 of the first titania film formed in the first filtration cell adjacent to the side surface of the support was different for each sample. As shown in Table 1, the second film thickness t2 of the second titania film formed in the second filtration cell adjacent to the inside of the first filtration cell was 0.0001 mm.

(Production of sample Nos. 4 to 6)
Sample No. 5 was used except that an alumina membrane was formed as a separation membrane instead of the titania membrane. 1 to 3 in the same process. 4 to 6 separation membrane structures were formed.

Sample No. The alumina films according to 4 to 6 were formed as follows.
First, a precursor solution (alumina sol solution) was prepared by diluting a sol solution obtained by hydrolyzing an aluminum alkoxide in the presence of nitric acid with ethanol. Next, an alumina sol solution was deposited on the inner surface of each filtration cell by a flow-down method to form an alumina membrane compact. At this time, by increasing the number of times the alumina sol flowed down in the filtration cell away from the center of the support, the thickness of the alumina membrane compact was increased as the filtration cell was closer to the side of the support.

  Next, the alumina membrane formed body was fired (400 ° C., 1 hour) to form an alumina membrane as a separation membrane. As shown in Table 1, the first film thickness t1 of the first alumina film formed in the first filtration cell adjacent to the side surface of the support was different for each sample. As shown in Table 1, the second film thickness t2 of the second alumina film formed in the second filtration cell adjacent to the inside of the first filtration cell was 0.0001 mm for all samples.

(Measurement of resistance coefficient of separation membrane and support)
Sample No. In the monolithic separation membrane structure according to 1 to 3, water (water temperature 25 ° C.) is continuously supplied to each filtration cell for 4320 hours in a state where the differential pressure between the inlet pressure and the outlet pressure of the titania membrane is 1 kgf / m ^2. Supplied. At the start of water supply, the permeation amount of water per unit time in the titania membrane was 0.02 m / h. Therefore, the resistance coefficient A (reciprocal of the amount of permeated water per unit time) of the titania film at the start of water supply was 48.

  And after supplying water for 4320 hours, the decreasing rate from the supply start time of the resistance coefficient A of a titania film | membrane was evaluated. In Table 1, samples whose resistance coefficient A decrease rate was 3% or more are evaluated as “x”, and samples whose resistance coefficient A decrease rate was 2% or more and less than 3% are evaluated as “Δ”. A sample having a decrease rate of the resistance coefficient A of less than 2% is evaluated as “◯”.

Sample No. In the monolithic separation membrane structure according to 4 to 6, water (water temperature 25 ° C.) is continuously supplied to each filtration cell for 4320 hours under the condition that the differential pressure between the inlet pressure and the outlet pressure of the alumina membrane is 1 kgf / m ^2. Supplied. At the start of water supply, the permeation amount of water per unit time through the alumina membrane was 0.004 m / h. Therefore, the resistance coefficient A (reciprocal of the amount of permeated water per unit time) of the alumina film at the start of water supply was 240.

  And after supplying water for 4320 hours, the decreasing rate from the supply start time of the resistance coefficient A of an alumina film was evaluated. In Table 1, samples whose resistance coefficient A decrease rate was 3% or more are evaluated as “x”, and samples whose resistance coefficient A decrease rate was 2% or more and less than 3% are evaluated as “Δ”. A sample having a decrease rate of the resistance coefficient A of less than 2% is evaluated as “◯”.

Sample No. In the monolithic separation membrane structure according to 1 to 6, after separating the separation membrane (titania membrane and alumina membrane) formed in each filtration cell with a drill, the differential pressure between the inlet pressure and the outlet pressure of the support is 1 kgf Water (water temperature 25 ° C.) was supplied to each filtration cell in a state of / m ² . The permeation amount of water per unit time on the support was 1.88 m / h. Therefore, the resistance coefficient B of the support (reciprocal of the amount of permeated water per unit time) was 0.5.

  The first thickness t1 of the first titania membrane formed in the first filtration cell adjacent to the side surface of the support is changed to the second thickness of the second titania membrane formed in the second filtration cell adjacent to the inside of the first filtration cell. Sample No. 2 made thicker than film thickness t2. In Nos. 2 and 3, sample No. 1 in which the first film thickness t1 is equivalent to the second film thickness t2. The reduction rate of the resistance coefficient A can be reduced more than 1. From this, it was found that the film lifetimes of the first titania film and the second titania film can be prolonged by making the first film thickness t1 larger than the second film thickness t2.

  Similarly, the 1st film thickness t1 of the 1st alumina membrane formed in the 1st filtration cell adjacent to the side of a support is made into the 2nd alumina formed in the 2nd filtration cell adjacent to the inside of the 1st filtration cell. Sample No. which is thicker than the second film thickness t2 of the film. In Samples 5 and 6, sample Nos. 1 and 2 in which the first film thickness t1 was equivalent to the second film thickness t2. The reduction rate of the resistance coefficient A could be reduced more than 4. From this, it was found that the film lifetimes of the first alumina film and the second alumina film can be prolonged by making the first film thickness t1 larger than the second film thickness t2.

  In addition, sample No. in which Expression (1): A × t1 + B × s1 = A × t2 + B × s2 is established. 2, sample no. Compared with 3, the reduction rate of the resistance coefficient A could be further reduced. From this, it was found that by satisfying the formula (1), the difference in the film life of the titania films having different distances from the side surface of the support can be suppressed.

  Similarly, the sample No. In sample No. 5, the sample No. Compared to 6, the reduction rate of the resistance coefficient A could be further reduced. From this, it was found that by satisfying the formula (1), the difference in the film life of the alumina films having different distances from the side surface of the support can be suppressed.

10 separation membrane structure 20 support S1 first end surface S2 second end surface S3 side surface 20a base material 20b intermediate layer 20c surface layer 23 separation membrane 231 first separation membrane 232 second separation membrane CL filtration cell CL1 first filtration cell CL2 second Filtration cell

Claims (2)

A monolithic separation membrane structure for separating a permeate component from a mixed fluid,
A support body having first and second filtration cells each extending from the first end surface to the second end surface, and an outflow surface through which the permeate component flows out;
A first separation membrane formed on the inner surface of the first filtration cell;
A second separation membrane formed on the inner surface of the second filtration cell;
With
The first filtration cell is closer to the outflow surface than the second filtration cell;
The first thickness of the first separation membrane, rather thick than the second thickness of the second separation membrane,
A first interval between the first separation membrane and the outflow surface is s1, a second interval between the second separation membrane and the outflow surface is s2, and the first film thickness of the first separation membrane is t1. When the second film thickness of the second separation membrane is t2,
A * t1 + B * s1 = A * t2 + B * s2 Formula (1)
(Where, in Formula (1), A is a resistance coefficient of the first separation membrane and the second separation membrane, and B is a resistance coefficient of the support) .
Monolith type separation membrane structure. The first film thickness is 1.2 times or more of the second film thickness.
The monolith type separation membrane structure according to claim 1.

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