JP2013226541A - Method for production of ceramic film complex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for production of a ceramic film complex, capable of forming a favorable ceramic film on the surface of a porous substrate cell.SOLUTION: A ceramic film precursor 25 is formed by applying a precursor sol 21 on the surface of the cell 2 of a porous substrate 10 through the steps of: disposing at one edge 11 of the porous substrate 10, a container 20 for storing the precursor sol which has a liquid discharge port 20a having a larger opening than the region in which the cell 2 is formed in one ridge 11 of the porous substrate 10; and making the precursor sol 21 stored in the container 20 free-fall from the whole area of the liquid discharge port 20a of the container 20 toward one edge 11 of the substrate 10 in such a state that the porous substrate 10, on which the container 20 is disposed, is arranged so that one edge 11 is disposed upward and the direction L to which the cell of the substrate 10 extends becomes vertical.

Description

  The present invention relates to a method for producing a ceramic membrane composite. More specifically, the present invention relates to a method for producing a ceramic membrane composite capable of forming a ceramic membrane satisfactorily on the surface of a porous substrate cell at least in the amount of the precursor sol for forming the ceramic membrane.

  A separation membrane may be used when only a specific type of material is separated or concentrated from a fluid in which a plurality of types of materials are mixed.

  The separation membrane is made of a structure having innumerable pores. The pores of the separation membrane have the property of allowing a specific type of substance to pass through. Therefore, if a fluid in which a substance that easily passes through the pores of the separation membrane and a substance that does not easily pass through the pores of the separation membrane are mixed is supplied on one surface of the separation membrane, it easily passes through the pores. The substance can pass through the pores and onto the other surface of the separation membrane (permeate the separation membrane). On the other hand, since it is difficult for a substance that hardly passes through the pores to pass through the separation membrane, it tends to stay on the one surface of the separation membrane. Therefore, it is possible to separate or concentrate a specific kind of substance from the plurality of kinds of substances by adding an operation of permeating the separation membrane with respect to a fluid in which a plurality of kinds of substances are mixed. Hereinafter, the “fluid in which a plurality of types of substances are mixed” to be separated or concentrated may be referred to as “liquid to be separated”.

  The ceramic membrane may be used by being disposed on a porous substrate. Such a composite composed of a porous substrate and a ceramic membrane may be referred to as a ceramic membrane composite. Examples of the porous substrate include a cylindrical substrate in which a plurality of cells extending from one end surface serving as a fluid flow path to the other end surface are formed. As a method for forming the ceramic membrane composite, for example, a method as shown in FIG. As shown in FIG. 17, the porous substrate 110 is fixed to the lower end of a cylindrical member 124 such as a wide-mouth funnel, and the precursor sol 121 for forming a ceramic film in the container 120 is placed from above the porous substrate 110. Pour and pass through the cell 112 of the porous substrate 110 (see, for example, Patent Document 1). FIG. 17 is a schematic view showing an example of a conventional method for producing a ceramic membrane composite.

  Examples of the ceramic film include a silica film, a titania film, and a zirconia film. For example, the silica film is a porous film that can be produced by hydrolysis and polycondensation of a silica compound such as alkoxysilane. The pores of the silica film have a property that allows a substance having a small molecular diameter such as water, carbon dioxide, and propylene to pass therethrough. Therefore, the silica membrane is used when separating water from a mixed liquid of water and ethanol obtained from biomass, or when separating carbon dioxide from combustion exhaust gas.

International Publication No. 2008/050812

  However, the conventional method for producing a ceramic membrane composite has a problem that a very large amount of precursor sol is required. That is, in the manufacturing method as shown in FIG. 17, in order to satisfactorily form a ceramic film on the surface of all the cells 112 formed on the porous substrate 110, a large amount of precursor sol is added to the porous substrate 110. Had to pour into.

  Further, in the conventional method for producing a ceramic membrane composite, if the amount of the precursor sol used is small, the ceramic membrane may not be formed on a part of the surface of the cell 112 of the porous substrate 110. There was also. In particular, when the substrate diameter is large, it is difficult to form a ceramic film on the surface of the cell 112 on the outer peripheral side of the porous substrate 110. As described above, the ceramic membrane composite in which the ceramic membrane is not formed on a part of the surface of the cell has a separation performance because the liquid to be separated passes through the portion where the ceramic membrane is not formed without being separated. It will drop significantly.

  The present invention has been made in view of the above-described problems. The present invention provides a method for producing a ceramic membrane composite capable of forming a ceramic membrane satisfactorily on the surface of a porous substrate cell at least in the amount of the precursor sol for forming the ceramic membrane.

  According to the present invention, the following method for producing a ceramic membrane composite is provided.

[1] A precursor sol for forming a ceramic film is applied to the surface of the cylindrical porous substrate on which a plurality of cells extending from one end surface to the other end surface serving as a fluid flow path are formed. A ceramic film precursor preparation step for forming a ceramic film precursor, and a heat treatment step for heat-treating the ceramic film precursor to form a ceramic film on the surface of the cell of the porous substrate, A precursor sol storage container having a liquid outlet having a larger opening than the region where the cells are formed on the one end face of the porous base material in the ceramic film precursor preparation step, The porous base material provided on the one end face side of the porous base material, and the precursor sol storage container is provided on the porous base material cell. The extending direction is the vertical direction In such a state, the precursor sol stored in the precursor sol storage container is allowed to fall freely from the entire liquid discharge port toward the one end surface of the porous substrate, A method for producing a ceramic membrane composite for forming a ceramic membrane precursor.

[2] The porous base material in which the precursor sol storage container in which the precursor sol is stored is disposed on the one end surface side, the one end surface being downward and the cell of the porous base material cell. From the state in which the extending direction is the vertical direction, the top and bottom of the one end surface and the other end surface of the porous substrate are reversed with one point on the cell extending direction as the rotation center. The ceramic film according to [1], in which the precursor sol stored in the precursor sol storage container is freely dropped toward the one end face of the porous base material by being rotated by 180 ° A method for producing a composite.

[3] When the length from the rotation center to the liquid level accumulated in the precursor sol storage container is a (m), the porous substrate is rotated 180 ° so that the top and bottom are reversed. The method for producing a ceramic membrane composite according to the above [2], wherein the speed of the precursor sol liquid surface part when the slab is made is √ (9.8a) m / sec or more.

[4] The amount of the precursor sol stored in the precursor sol storage container is ² SmL or more when the area of the one end surface of the porous substrate is Scm ² [1] The manufacturing method of the ceramic membrane composite in any one of-[3].

[5] The method for producing a ceramic membrane composite according to any one of [1] to [4], wherein an outer diameter of the one end face of the porous substrate is 50 mm or more.

[6] The method for producing a ceramic membrane composite according to any one of [1] to [5], wherein the viscosity of the precursor sol is 1.0 to 20 mPa · s.

[7] The method for producing a ceramic membrane composite according to any one of [1] to [6], wherein the ceramic membrane is a silica membrane.

[8] The method for producing a ceramic membrane composite according to [7], wherein the silica membrane is a silica membrane containing a p-tolyl group.

  The method for producing a ceramic membrane composite of the present invention comprises the following ceramic membrane precursor preparation step. That is, first, a precursor sol storage container having a liquid outlet having a larger opening than the region where cells are formed on one end surface of the porous substrate is connected to one end surface of the porous substrate. On the side. Thereafter, the porous base material in which the precursor sol storage container is disposed is arranged so that one end surface is upward and the cell extending direction of the porous base material is the vertical direction. In that state, the precursor sol stored in the precursor sol storage container is allowed to fall freely from the entire liquid discharge port of the precursor sol storage container toward one end surface of the porous substrate. Forming a ceramic film precursor;

  By comprising in this way, precursor sol can be poured evenly with respect to the whole one end surface of a porous base material. At this time, the precursor sol temporarily stays on one end face of the porous substrate, and then the precursor sol moves to the other end face side while passing through each cell. Thereby, a ceramic membrane precursor can be uniformly formed on the surface of all cells of the porous substrate. Therefore, according to the method for producing a ceramic membrane composite of the present invention, a ceramic membrane can be satisfactorily formed on the surface of all the cells of the porous substrate at least in the amount of the precursor sol for forming the ceramic membrane. .

  In the method for producing a ceramic membrane composite of the present invention, the method of allowing the precursor sol to fall freely from the entire liquid discharge port of the precursor sol storage container toward one end surface of the porous substrate is as follows. It is preferable that First, a porous base material in which a precursor sol storage container in which a precursor sol is stored is arranged on one end surface side, one end surface is downward, and the cell extending direction of the porous base material is a vertical direction. Arrange as follows. From this state, the center of rotation of one point in the cell extending direction is rotated 180 ° so that the top and bottom of one end surface and the other end surface of the porous substrate are reversed. With this configuration, the precursor sol can be freely dropped from the liquid discharge port of the precursor sol storage container toward one end surface of the porous substrate by a simpler method.

It is a schematic diagram for demonstrating one Embodiment of the manufacturing method of the ceramic membrane composite of this invention. It is a perspective view which shows typically the process of forming a ceramic membrane precursor in the ceramic membrane precursor preparation process in one Embodiment of the manufacturing method of the ceramic membrane composite of this invention. It is a schematic sectional drawing for demonstrating a ceramic membrane precursor preparation process. It is a schematic sectional drawing for demonstrating a ceramic membrane precursor preparation process, and shows the next operation of FIG. 3A. It is a schematic sectional drawing for demonstrating a ceramic membrane precursor preparation process, and shows the next operation of FIG. 3B. It is a schematic sectional drawing for demonstrating a ceramic membrane precursor preparation process, and shows the operation | movement following FIG. 3C. It is a schematic diagram for demonstrating the measuring method of the vacuum degree of a cell. It is an expansion schematic diagram which expands and shows one cell in FIG. 2 is a photograph of one end face of the silica membrane composite produced according to Example 1. 4 is a graph showing measurement results of cell vacuum degree of the silica membrane composite produced according to Example 1. FIG. 6 is a graph showing measurement results of cell vacuum degree of the silica membrane composite produced in Comparative Example 1. FIG. 6 is a graph showing the measurement results of the degree of vacuum of the cell of the silica membrane composite produced according to Example 2. 6 is a graph showing measurement results of cell vacuum degree of the silica membrane composite produced in Comparative Example 2. 6 is a graph showing measurement results of cell vacuum degree of the silica membrane composite produced according to Example 3. 6 is a graph showing measurement results of cell vacuum degree of the silica membrane composite produced by Comparative Example 3. FIG. It is a graph which shows the measurement result of the vacuum degree of a cell of the silica membrane composite manufactured by Example 4. It is a graph which shows the measurement result of the vacuum degree of a cell of the silica membrane composite manufactured by the comparative example 4. 6 is a graph showing the measurement results of the degree of vacuum of the cell of the silica membrane composite produced according to Example 5. 10 is a graph showing the measurement results of the degree of vacuum of the cell of the silica membrane composite produced by Comparative Example 5. It is a schematic diagram which shows an example of the manufacturing method of the conventional ceramic membrane composite.

  Next, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and it is understood that design changes, improvements, and the like can be added as appropriate based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. Should.

(1) Manufacturing method of ceramic membrane composite:
One embodiment of the method for producing a ceramic membrane composite of the present invention comprises a ceramic membrane precursor preparation step A and a heat treatment step B as shown in FIG. FIG. 1 is a schematic view for explaining one embodiment of a method for producing a ceramic membrane composite of the present invention. The ceramic film precursor preparation step A is performed on the surface of the cell 2 of the cylindrical porous substrate 10 in which a plurality of cells 2 extending from one end surface 11 to the other end surface 12 serving as a fluid flow path are formed. In this process, a ceramic film precursor 25 is formed by applying a film forming precursor sol. The heat treatment step B is a step in which the ceramic film precursor 25 is heat treated to form the ceramic film 26 on the surface of the cell 2 of the porous substrate 10. In the heat treatment step B, it is preferable to form the ceramic film 26 by heating the porous substrate 10 having the ceramic film precursor 25 formed on the surface of the cell 2 together with the ceramic film precursor 25. By comprising in this way, the cylindrical porous base material 10 in which the several cell 2 extended from one end surface 11 to the other end surface 12 was formed, and the surface of the cell 2 of the porous base material 10 was arrange | positioned. The ceramic membrane composite 100 provided with the ceramic membrane 26 can be manufactured.

  The ceramic membrane precursor production step A in the method for producing a ceramic membrane composite of the present embodiment is performed as shown in FIG. FIG. 2 is a perspective view schematically showing a process of forming the ceramic film precursor in the ceramic film precursor manufacturing process in the method of manufacturing the ceramic film composite of the present embodiment. As shown in FIG. 2, in the ceramic film precursor preparation step A, first, a liquid outlet having a larger opening than the region where the cell 2 is formed on one end face 11 of the porous substrate 10. A precursor sol storage container 20 having 20 a is disposed on one end face 11 side of the porous substrate 10. Thereafter, the porous substrate 10 in which the precursor sol storage container 20 is disposed is disposed such that one end surface 11 is on the upper side and the cell extending direction L of the porous substrate 10 is the vertical direction. In this state, the precursor sol 21 stored in the precursor sol storage container 20 is directed from the entire liquid discharge port 20a of the precursor sol storage container 20 toward one end face 11 of the porous substrate 10. The ceramic film precursor 25 is formed by allowing it to fall freely. At this time, one end surface 11 and the other end surface 12 of the porous substrate 10 are sealed with glass or the like, and the precursor sol 21 is not attached to the surface other than the surface of the cell 2.

  By configuring in this way, the precursor sol 21 can be poured evenly over the entire area of the one end face 11 of the porous substrate 10. That is, the precursor sol 21 stored in the precursor sol storage container 20 having the liquid discharge port 20a as described above is dropped on one end face 11 of the porous substrate 10 by free fall from the entire liquid discharge port 20a. Therefore, the flow of the precursor sol 21 is less likely to be uneven. At this time, the precursor sol 21 stays temporarily on one end face 11 of the porous substrate 10, and then the other end face 12 side while the precursor sol 21 passes through each cell 2. Move up. Thereby, the ceramic film precursor 25 can be uniformly formed on the surface of all the cells 2 of the porous substrate 10. Therefore, according to the method for producing a ceramic membrane composite of the present embodiment, the amount of the precursor sol 21 for forming the ceramic membrane can be satisfactorily formed on the surface of the cell 2 of the porous substrate 10. Can do. The precursor sol storage container 20 may have a cylindrical shape as long as the precursor sol can be evenly dropped.

  In FIG. 2, a precursor sol storage container 20 having a liquid discharge port 20 a having the same diameter as the outer peripheral diameter of the porous substrate 10 is used. By using the precursor sol storage container 20 having the liquid discharge port 20a having the same diameter as the outer peripheral diameter of the porous base material 10, unevenness in the flow of the precursor sol 21 is less likely to occur.

  The porous substrate 10 used in the method for manufacturing a ceramic membrane composite of the present embodiment has a lotus-like shape in which a plurality of cells 2 extending from one end face 11 to the other end face 12 serving as a fluid flow path are formed. A honeycomb substrate is preferable. Such a lotus-like or honeycomb-like substrate is sometimes referred to as a “monolith substrate”.

  “A region in which the cells 2 on one end surface 11 of the porous substrate 10 are formed” includes all the cells 2 opened on the one end surface 11 of the porous substrate 10 and is located on the outermost periphery. A region formed by connecting points on the periphery of each cell. Hereinafter, the “region in which the cell 2 is formed on the one end surface 11 of the porous substrate 10” may be referred to as a “cell formation region”. The precursor sol storage container 20 used in the method for manufacturing a ceramic membrane composite of the present embodiment is configured such that the size of the liquid discharge port 20a is larger than the size of the cell formation region. With this configuration, when the precursor sol 21 is freely dropped from the precursor sol storage container 20, the precursor sol 21 flows evenly into all the cells 2 opened on one end face 11. Can be made. In the precursor sol storage container 20, the liquid discharge port 20 a has the same size as the outer periphery of one end surface 11 of the porous substrate 10, or the one end surface 11 of the porous substrate 10. The size is preferably larger than the outer periphery. In that case, a V-ring seal made of a fluororesin may be used to connect the porous substrate 10 and the precursor sol storage container 20. By setting the size of the liquid discharge port 20 a to the above size, the arrangement of the precursor sol storage container 20 on the one end surface 11 of the porous substrate 10 is facilitated. In addition, the precursor sol 21 is easily allowed to uniformly flow into all the cells 2 opened on the one end face 11.

  “Precursor sol” for forming a ceramic film means a sol capable of forming a ceramic film by forming the precursor sol into a film and heat-treating the film-shaped precursor sol. To do. Further, the “ceramic film precursor” is a film obtained by forming a precursor sol into a film shape, and means a state before the heat treatment of the ceramic film. About the precursor sol used for the manufacturing method of the ceramic membrane composite of this embodiment, what was comprised similarly to the precursor sol used for the manufacturing method of the conventional ceramic membrane composite can be used suitably. Examples of the ceramic film produced by the method for producing a ceramic film composite of the present embodiment include a silica film, a titania film, and a zirconia film, and each may contain an organic functional group. These ceramic membranes are formed with a plurality of pores leading from one surface of the ceramic membrane to the other surface, and it is possible to separate or concentrate a specific kind of substance from a plurality of kinds of substances. This membrane functions as a proper separation membrane. In the method for producing a ceramic membrane composite of the present embodiment, the type of precursor sol to be used can be appropriately selected according to the type of ceramic membrane to be produced. For example, when producing a silica film, a ceramic film precursor production step is performed using a precursor sol for forming a silica film.

  The heat treatment conditions of the heat treatment step B are not particularly limited as long as the ceramic film 26 can be formed by heating the ceramic film precursor 25. The heat treatment conditions in the heat treatment step B can be appropriately determined according to the type of the precursor sol used in the ceramic film precursor preparation step A.

  Hereinafter, the manufacturing method of the ceramic membrane composite of this embodiment will be described in more detail for each step.

(1-1) Ceramic film precursor preparation step A:
As described above, the ceramic film precursor production step A is performed using the precursor sol storage container 20 having the liquid discharge port 20a having a larger opening than the cell formation region. When the precursor sol storage container 20 is disposed on the one end surface 11 side of the porous substrate 10, the liquid discharge port 20 a covers the cell formation region on the one end surface 11 of the porous substrate 10. It is preferable to do so. As a result, the landing position of the precursor sol 21 that has fallen freely toward one end surface 11 of the porous substrate 10 includes at least the cell formation region, and all of the cells 2 opened in the one end surface 11 The precursor sol 21 can be made to flow evenly.

  When the precursor sol 21 is allowed to freely fall from the entire liquid discharge port 20a of the precursor sol storage container 20 toward the one end surface 11 of the porous base material 10, the same timing as possible from the entire liquid discharge port 20a. It is preferable that the precursor sol 21 is freely dropped (that is, discharged). For example, if the precursor sol 21 is discharged first from a part of the liquid discharge port 20a, the precursor sol 21 is completely discharged before the precursor sol 21 is discharged from the other part of the liquid discharge port 20a. There is. Further, even if the precursor sol 21 is freely dropped from the entire liquid discharge port 20a, if the discharge timing is shifted, the precursor sol 21 is temporarily formed on one end surface 11 of the porous substrate 10. It may be difficult to accumulate. For this reason, in the method for producing a ceramic membrane composite of the present embodiment, the ceramic membrane precursor production step A is preferably performed by a method as shown in FIGS. 3A to 3D. 3A to 3D are schematic cross-sectional views for explaining a ceramic film precursor manufacturing step.

  As shown in FIG. 3A, a porous base material 10 in which a precursor sol storage container 20 in which a precursor sol 21 is stored is arranged on one end face 11 side, and the one end face 11 is downward and the porous base material is placed. It arrange | positions so that the direction L where the 10 cells 2 extend may become a perpendicular direction. The porous substrate 10 has a cylindrical shape in which a plurality of cells 2 extending from one end surface 11 to the other end surface 12 are formed.

  The precursor sol storage container 20 shown in FIGS. 3A to 3D has a bottomed cylindrical shape having a liquid discharge port 20 a having the same size as the peripheral edge of one end surface 11 of the porous substrate 10. Such a liquid discharge port 20a of the precursor sol storage container 20 is fitted to the end of the porous substrate 10 on the one end face 11 side, so that the porous substrate 10 and the precursor sol storage container 20 Is connected. There is no particular limitation on the method for connecting the porous substrate 10 and the precursor sol storage container 20. It is preferable that the peripheral edge of one end surface 11 of the porous substrate 10 and the liquid discharge port 20a are fixed in a liquid-tight state. With this configuration, when the precursor sol 21 is discharged from the liquid discharge port 20a of the precursor sol storage container 20, the precursor sol 21 from the peripheral edge of the one end surface 11 of the porous substrate 10 is used. Can be effectively prevented.

  In FIG. 3A, a precursor sol collection container 28 is disposed on the other end face 12 side of the porous substrate 10. The precursor sol collection container 28 preferably has a liquid collection port 28a having a larger opening than the region where the cell 2 is formed on the other end surface 12 of the porous substrate 10. The precursor sol collection container 28 circulates the precursor sol 21 stored in the precursor sol storage container 20 through the inside of the cell 2 of the porous substrate 10, and then supplies the excess precursor sol 21. A container for collection. The precursor sol collection container 28 is preferably configured in the same manner as the precursor sol storage container 20. Further, the method for connecting the precursor sol collection container 28 and the porous substrate 10 is not particularly limited, and the same method as the method for connecting the porous substrate 10 and the precursor sol storage container 20 is used. Can do. The precursor sol collection container 28 is not always necessary, and the bucket may receive excess sol.

  Next, as shown in FIG. 3A, one end surface of the porous substrate 10 from the state in which the one end surface 11 of the porous substrate 10 is in the downward direction, with one point on the cell extending direction L as the rotation center. Rotate 180 degrees so that the top and bottom of 11 and the other end face 12 are reversed. That is, the porous substrate 10 in the state shown in FIG. 3A is arranged so that the one end surface 11 is on the upper side and the extending direction L of the cells 2 of the porous substrate 10 is the vertical direction. Rotate 180 ° to the state shown in FIG. 3B.

  At this time, the inertial force acts on the precursor sol 21 in the precursor sol storage container 20 by the rotational motion. The precursor sol 21 receives centripetal force from the bottom surface of the precursor sol storage container 20. In the method for producing a ceramic membrane composite of the present embodiment, it is preferable to rotate the porous substrate 10 by 180 ° at a speed at which the above-described inertial force and centripetal force are balanced. In the method for producing a ceramic membrane composite of the present embodiment, when the porous substrate 10 is rotated 180 °, one end face 11 as shown in FIG. ), The precursor sol 21 is more preferably pressed against the bottom surface of the precursor sol storage container 20.

  When the porous substrate 10 is held in a state as shown in FIG. 3B, the precursor sol 21 pressed against the bottom surface of the precursor sol storage container 20 is removed from the porous substrate 10 as shown in FIG. 3C. Free fall toward one end face 11. Rotating the porous substrate 10 by 180 ° as described above is sometimes referred to as “upside down”. The position of the rotation center in the upside down is not particularly limited as long as the rotation is such that the inertial force and the centripetal force in the precursor sol 21 are balanced.

  As shown in FIG. 3D, the precursor sol 21 that has freely dropped toward one end surface 11 of the porous substrate 10 passes through the inside of the cell 2 of the porous substrate 10, while It moves toward the other end face 12. At this time, the precursor sol 21 adheres to the surface of the cell 2 to form a ceramic film precursor. The surplus precursor sol 21 flows out of the opening of the cell 2 on the other end face 12 and is collected in the precursor sol collection container 28. By comprising in this way, a ceramic film precursor can be formed by a very simple method.

  In the ceramic film precursor preparation step A by such a top-to-bottom reversal, the speed of the precursor sol liquid surface portion when rotating 180 ° so that the top and bottom of the porous substrate is reversed is as follows. It is preferable. “The velocity of the precursor sol liquid surface portion when rotating 180 °” means that the “precursor sol accumulated in the precursor sol storage container” is used when rotating 180 ° so that the top and bottom of the porous substrate is reversed. "Tangential velocity" measured at "the position of the liquid level". Here, the “position of the liquid level of the precursor sol accumulated in the precursor sol reservoir” refers to the length from the rotation center in the upside down to the liquid level of the precursor sol accumulated in the precursor sol reservoir. When the height is a (m), it means a position a (m) away from the center of rotation. Therefore, the “velocity of the precursor sol liquid surface portion when rotating 180 °” is “the radius OA when the rotation center is“ point O ”and the position of the liquid surface of the precursor sol is“ point A ”. The tangential velocity at point A in FIG.

  In the ceramic film precursor preparation step A by upside down, the speed of the precursor sol liquid surface portion is the length from the rotation center in the upside down to the liquid surface of the precursor sol accumulated in the precursor sol storage container. Is preferably √ (9.8a) m / sec or more, where a (m). By comprising in this way, top-and-bottom reversal can be performed satisfactorily in a state where inertial force and centripetal force are balanced. In addition, even if the velocity of the precursor sol liquid surface portion at the time of reversal of the top and bottom is somewhat slower than the above-mentioned “√ (9.8a) m / sec”, In some cases, it is possible to make it fall freely toward the end face of the. For example, in consideration of the physical properties of the precursor sol and the like, a rotation speed at which the inertial force and centripetal force in the precursor sol are balanced can be appropriately selected.

  In the ceramic membrane precursor production step A in the method for producing a ceramic membrane composite of the present embodiment, the above-described porous substrate 10 is rotated by 180 ° so that the top and bottom of the one end face 11 and the other end face 12 are reversed. The method is not limited. That is, the ceramic sol precursor can be formed by allowing the precursor sol stored in the precursor sol storage container to freely fall from the entire area of the liquid discharge port toward the entire end face of the porous substrate. Any method is possible. For example, although not shown, an opening / closing mechanism may be provided at the liquid discharge port of the precursor sol storage container. The porous base material in which the precursor sol storage container in a state where the opening and closing mechanism is closed is disposed so that one end face is upward and the cell extending direction of the porous base material is the vertical direction, Thereafter, the opening / closing mechanism may be opened to allow the precursor sol to fall freely from the entire liquid discharge port. As the opening / closing mechanism, a plate-like member is arranged so as to close the liquid discharge port of the precursor sol storage container, and the liquid discharge port is opened and closed by pulling out the plate-like member. Can be mentioned. By quickly pulling out the plate-like member, the precursor sol can be freely dropped simultaneously from the entire liquid discharge port of the precursor sol storage container.

  Further, when the precursor sol 21 is accumulated at the upper end of the porous substrate 10 by making a hole near the bottom of the precursor sol storage container 20 as shown in FIG. It is also a preferable embodiment that the hole is opened to release air. The hole of the precursor sol storage container 20 described above serves as an air vent valve. With this configuration, air suction during negative pressure when the precursor sol 21 freely falls from the hole, and air that has flowed into the precursor sol storage container 20 from the precursor sol collection container 28 are obtained. The discharge can be performed satisfactorily. The vicinity of the bottom of the precursor sol storage container 20 refers to the bottom surface of the precursor sol storage container 20 and the side surface in the vicinity of the bottom surface.

The amount of the precursor sol stored in the precursor sol storage container is preferably ² SmL or more when the area of one end face of the porous substrate is Scm2. The above-mentioned “area of one end surface of the porous substrate” means an area (cm ² ) surrounded by the periphery of one end surface of the porous substrate. For example, when it is assumed that the precursor sol that has fallen freely on one end face of the porous substrate does not flow into the cell from one end face of the porous substrate and stays on one end face instantaneously. It is preferable that the liquid level of the precursor sol has a sol amount of 2 cm or more. By using the amount of the precursor sol described above, a ceramic film can be favorably formed on the surfaces of all the cells of the porous substrate. In the method for producing a ceramic membrane composite of the present embodiment, if the amount of the precursor sol is 2 SmL or more, the ceramic membrane can be satisfactorily formed on the surfaces of all the cells of the porous substrate. For this reason, the usage-amount of precursor sol can be reduced compared with the conventional manufacturing method.

  As a precursor sol for producing the ceramic film precursor, a sol for forming a silica film, a sol for forming a titania film, a sol for forming a zirconia film, or the like can be used. Examples of the sol for forming a silica film include a sol for forming a silica film in which a silica compound containing at least one of tetraethoxysilane, an aryl group, and an alkyl group is used as an alkoxide. As the silica compound, alkoxysilane can be used. Examples of the alkoxysilane containing an aryl group include phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, p-tolyltrimethoxysilane, o-tolyltrimethoxysilane, and m-tolyltrimethoxy. Silane, p-xylyltrimethoxysilane, o-xylylmethoxysilane, m-xylyltrimethoxysilane, and the like can be used. Examples of the alkoxysilane containing an alkyl group include methyltrimethoxysilane, methyltriethoxysilane, dimethoxydimethylsilane, trimethylmethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, pentyltrimethoxysilane, Examples include hexyltrimethoxysilane, heptyltrimethoxysilane, and octyltrimethoxysilane. Examples of the sol for forming a titania film include a sol for forming a titania film using titanium tetraisopropoxide as an alkoxide. Examples of the sol for forming a zirconia film include a sol for forming a zirconia film using zirconium tetraethoxide as an alkoxide. By using the above-described “sol for forming a silica film in which a silica compound containing at least one of an aryl group and an alkyl group is used as an alkoxide”, the ability to selectively separate aromatic compounds and alcohol are selectively separated. A ceramic membrane composite having performance is obtained.

  In particular, the silica film obtained by the above sol for forming a silica film is preferably a silica film containing a p-tolyl group. Such a silica membrane containing a p-tolyl group can be suitably used as a separation membrane having the ability to selectively separate alcohol.

Examples of a method for producing such a precursor sol (sol for forming a silica film) include the following methods. First, trimethoxy (p-tolyl) silane and ethanol are mixed and stirred at 4 ° C. Next, after trimethoxy (p-tolyl) silane and ethanol are sufficiently mixed, an aqueous nitric acid solution is added little by little for hydrolysis. After adding a predetermined amount of nitric acid aqueous solution, the mixture is stirred. For example, the mixture is stirred for 1 hour at 4 ° C., and then the mixture is heated to 50 ° C. and further stirred for 3 hours. Thereafter, ethanol is added so that the concentration of the silica sol in the mixed solution is 2.0 mass% in terms of SiO ₂ . In this way, a precursor sol can be produced.

  The viscosity of the precursor sol is preferably 1.0 to 20 mPa · s, more preferably 1.1 to 10 mPa · s at room temperature of 20 ° C., and 1.2 to 4.1 mPa · s. It is particularly preferred. When the viscosity of the precursor sol is within the above numerical range, the precursor sol does not excessively penetrate into the porous base material, and the precursor sol easily flows down in the cell. In particular, when the viscosity of the precursor sol is less than 1.0 mPa · s, the precursor sol is often contained in the porous substrate. In addition, when the viscosity of the precursor sol exceeds 20 mPa · s, the precursor sol may hardly flow down in the cell. The viscosity of the precursor sol is a value measured with a conical rotational viscometer.

  As the porous substrate used in the method for producing a ceramic membrane composite of the present embodiment, a porous substrate having the same structure as the porous substrate used in a conventionally known method for producing a ceramic membrane composite can be used. . As the shape of the porous substrate, the shape of the cross section perpendicular to the cell extending direction is preferably circular, elliptical or polygonal. The material of the porous substrate is preferably made of a ceramic material such as alumina, silica, cordierite, mullite, titania, zirconia, silicon carbide, etc., from the viewpoint of strength and chemical stability. The porosity of the porous substrate is preferably about 25 to 55% from the viewpoint of the strength and permeability of the porous substrate. Moreover, it is preferable that the average pore diameter of a porous base material shall be about 0.005-5 micrometers.

  There is no restriction | limiting in particular about the magnitude | size of the outer diameter in one end surface of a porous base material. It is preferable that the outer diameter in one end surface of a porous base material is 50-300 mm, and it is still more preferable that it is 50-200 mm. If the outer diameter of one end face is too large, it may be difficult to produce the ceramic membrane composite. For example, when the outer diameter of one end surface exceeds 300 mm, it may be difficult to manufacture the ceramic membrane composite. The manufacturing method of the ceramic membrane composite of this embodiment can be said to be a particularly effective manufacturing method when the outer diameter at one end face of the porous substrate is 50 mm or more. For example, this is particularly effective when the porous substrate is cylindrical and the diameter of one end face of the porous substrate is 50 mm or more. In the conventional method for producing a ceramic membrane composite, when the diameter of one end face of a porous substrate is 50 mm or more, a ceramic membrane is formed over the entire surface of all cells of the porous substrate. Required the use of very large amounts of precursor sol. In the method for producing a ceramic membrane composite of the present embodiment, even if the outer diameter of one end surface of the porous substrate is 50 mm or more, the ceramic membrane is excellent over the entire surface of all the cells of the porous substrate. Can be formed.

  The “outer diameter at one end surface of the porous substrate” means the diameter (outer diameter) of the circle when the shape of one end surface of the porous substrate is a circle. In addition, the “outer diameter at one end surface of the porous substrate” is the same area as the area of one end surface of the porous substrate when the shape of the one end surface of the porous substrate is not a circle. It shall mean the diameter (outer diameter) of the circle.

  There is no restriction | limiting in particular about the length of the cell extending direction of a porous base material. The length of the porous substrate in the cell extending direction is preferably 20 to 2000 mm, more preferably 30 to 1500 mm, and particularly preferably 40 to 1000 mm. When the length in the cell extending direction is less than 20 mm, the film area of the ceramic film may be small. When the length in the cell extending direction exceeds 2000 mm, it may be difficult to produce and handle the porous substrate.

  There is no restriction | limiting in particular also about the number of the cells formed in a porous base material. About the number of cells, it can determine suitably according to the magnitude | size of the outer diameter of a porous base material. Further, the number of cells can be appropriately determined in consideration of the membrane area per volume and the strength. The number of cells is, for example, preferably 10 to 10,000, more preferably 20 to 5000, and particularly preferably 50 to 3000. There is no particular limitation on the equivalent diameter of the opening of one cell. For example, the equivalent diameter of the opening of the cell is preferably 0.5 to 30 mm, preferably 1 to 10 mm, and particularly preferably 1.5 to 5 mm. The “equivalent diameter of the opening portion of the cell” means the diameter (inner diameter) of the circle when the shape of the opening portion of the cell is a circle. Further, the “equivalent diameter of the cell opening” means the diameter (inner diameter) of a circle having the same area as the area of the opening when the shape of the cell opening is not a circle.

  The ceramic film precursor thus formed becomes a ceramic film by performing the heat treatment step B. Before performing the heat treatment step B, it is preferable to dry the ceramic film precursor. As a method for drying the ceramic film precursor, ventilation drying in which air is directly fed into the cell is preferable.

(1-2) Heat treatment step B:
The heat treatment step B is a step of heat-treating the ceramic film precursor formed in the ceramic film precursor preparation step A to form a ceramic film on the surface of the cell of the porous substrate. That is, in the heat treatment step B, the ceramic film precursor is heat treated to become a ceramic film. Thus, according to the method for producing a ceramic membrane composite of the present embodiment, the ceramic membrane composite comprising the porous substrate and the ceramic membrane disposed on the surface of the cell of the porous substrate. The body can be manufactured.

  There is no restriction | limiting in particular about the conditions of heat processing process B, It can carry out by the method similar to the heat processing process in the manufacturing method of a conventionally well-known ceramic membrane composite. About the temperature of heat processing, it can determine suitably according to the kind of precursor sol for forming a ceramic membrane precursor. For example, when the sol for forming a silica film described above is used as a precursor sol, the temperature of the heat treatment is preferably 100 to 800 ° C, more preferably 200 to 700 ° C, and more preferably 300 to 600. It is particularly preferable that the temperature is C. The heat treatment time is preferably 0.01 to 100 hours, more preferably 0.05 to 20 hours, and particularly preferably 0.1 to 10 hours. By performing the heat treatment step B under such conditions, a high-performance silica film can be formed satisfactorily. The “silica film” produced by the method for producing a ceramic film composite of the present embodiment is “silica film obtained after the heat treatment step B with respect to the total mass of the dried ceramic film precursor (ie, silica film precursor)”. In order to separate aromatics and alcohols, it is preferable that the ratio of the total mass of is 38% by mass or more and 85% by mass or less.

  The heat treatment step B is preferably performed continuously from the drying of the ceramic film precursor performed in the ceramic film precursor preparation step A. Further, the ceramic film precursor preparation step A and the heat treatment step B may be repeated a plurality of times. That is, after the ceramic film is formed on the surface of the cell of the porous substrate by the heat treatment process B, the ceramic film precursor preparation process A is performed again. Thereby, a ceramic film precursor is further formed on the surface of the ceramic film obtained by the heat treatment step B. Thereafter, the ceramic film precursor formed on the surface of the ceramic film may be heat-treated again to form a ceramic film composed of two or more layers. By comprising in this way, the film thickness of the ceramic membrane in a ceramic membrane composite can be adjusted. The ceramic film precursor preparation step A and the heat treatment step B may be repeated three or more times.

(1-3) Other steps in the method for producing a ceramic membrane composite of the present embodiment:
The manufacturing method of the ceramic membrane composite of this embodiment may further include other steps other than the ceramic membrane precursor preparation step A and the heat treatment step B described so far. That is, other processes than the ceramic film precursor preparation process A and the heat treatment process B performed in a conventionally known method for producing a ceramic film composite can be appropriately performed as necessary. Examples of other processes include a pretreatment process in which a pervaporation test is performed to change the initial state of film performance.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

Example 1
In Example 1, a silica membrane composite in which the ceramic membrane was a silica membrane was produced. As a porous substrate for producing the silica membrane composite, a cylindrical porous substrate having a diameter of one end face of 90 mm was prepared. The length of the porous substrate in the cell extending direction was 100 mm. In the porous substrate, 618 cells extending from one end surface to the other end surface are formed. The cell diameter was 1.6 mm. In addition, the shape of the cell in the cross section perpendicular to the cell extending direction of the porous substrate was circular. “Cell diameter” refers to the diameter of a circular void portion (cell) perforated in the porous substrate in a cross section perpendicular to the cell extending direction of the porous substrate (that is, the diameter of the opening). It is. The total open area of the cells on one end face of the porous substrate was 1243 mm ² . In Table 1, “the diameter of one end face of the porous substrate (mm)”, “the length of the porous substrate in the cell extending direction (mm)”, “the number of cells (pieces)”, “the number of cells” “Diameter (mm)” and “Total open area of cell (mm ² )” are shown.

Moreover, the total area of the surface of the cell of the porous substrate was 0.311 m ² . For this reason, the area of the silica membrane produced by the method for producing a silica membrane composite of Example 1 is 0.311 m ² .

  Next, a precursor sol used in the method for producing the silica membrane composite of Example 1 was produced by the following method. First, trimethoxy (p-tolyl) silane and ethanol were mixed, and the mixture was sufficiently stirred at a temperature of 4 ° C. After thoroughly mixing trimethoxy (p-tolyl) silane and ethanol, an aqueous nitric acid solution was added little by little for hydrolysis. After adding a predetermined amount of nitric acid aqueous solution, the mixture was further stirred for 1 hour in a state of 4 ° C. Next, the mixed liquid stirred for 1 hour was heated to 50 ° C. and further stirred for 3 hours.

Thereafter, ethanol was added so that the concentration of the silica sol in the mixed solution was 2.0% by mass in terms of SiO ₂ . The obtained mixture was used as a precursor sol.

By using the obtained precursor sol, silica as a ceramic film precursor is formed on the surface of the cell 2 of the porous substrate 10 by the ceramic film precursor preparation step A by upside down as shown in FIGS. 3A to 3D. A film precursor was formed. Specifically, 460 ml of the obtained precursor sol was weighed and stored in a precursor sol storage container 20 as shown in FIG. 3A. Thereafter, from the state in which one end surface 11 of the porous substrate 10 is in the downward direction, one end surface 11 and the other end surface 12 of the porous substrate 10 are centered on one point on the cell extending direction L. It was rotated 180 ° so that the top and bottom were reversed. At this time, the porous substrate 10 was rotated 180 ° at such a speed that the inertial force and the centripetal force with respect to the precursor sol 21 stored in the precursor sol storage container 20 were balanced. That is, as shown in FIG. 3B, upside down is performed at such a speed that the precursor sol 21 is pressed against the bottom surface of the precursor sol storage container 20 until one end face 11 of the porous base material 10 is upward. went. Specifically, the porous substrate 10 is so formed that the velocity of the precursor sol liquid surface portion of the precursor sol storage container is 0.99 m / sec and the top and bottom of one end surface 11 and the other end surface 12 are reversed. Was rotated 180 °. Thereafter, as shown in FIG. 3C, the precursor sol 21 pressed against the bottom surface of the precursor sol storage container 20 freely dropped toward one end surface 11 of the porous substrate 10. At this time, the precursor sol 21 that freely dropped does not flow into the cell 2 from the one end surface 11 of the porous substrate 10 but instantaneously stays on the one end surface 11. The height of the liquid surface of the body sol 21 is defined as “in-cylinder sol height”. The in-cylinder sol height was 7.2 cm. Table 1 shows “amount of precursor sol used (mL)” and “in-cylinder sol height (cm)”. The ratio of the total opening area (mm ² ) of the porous base material cells used in each of the examples and the comparative examples to the total opening area (mm ² ) of the porous base material cells used in Example 5 described later. , And “aperture area ratio”. Table 1 shows the “opening area ratio” of the porous substrate used in Example 1.

  In addition, when the above-described upside-down inversion was actually performed, it was visually determined whether or not the precursor sol that had fallen freely was evenly accumulated on one end face of the porous substrate. The case where the precursor sol was evenly accumulated on one end face was defined as “A”. A case where the precursor sol was collected on one end face but the liquid level was not uniform was designated as “B”. The determination result is shown in the column of “deposition result after inversion” in Table 1.

  Thereafter, the precursor sol storage container and the precursor sol collection container were removed from the porous substrate, and the silica film precursor formed on the surface of the cell of the porous substrate was blown and dried. Ventilation drying was performed by applying air to one end face of the porous substrate and allowing air to flow through the cells of the porous substrate. The wind speed was 10 m / s.

  Then, the heat processing process B which heat-processes the porous base material with which the silica membrane precursor was formed at 400 degreeC for 1 hour was performed. In Example 1, using the porous base material after finishing the heat treatment step B, the ceramic film precursor preparation step A is performed again by the same method as the ceramic film precursor preparation step A described so far. Further, the heat treatment step B was performed in the same manner as described above. In Example 1, a silica membrane composite was manufactured by performing ceramic membrane precursor preparation step A and heat treatment step B three times in total.

  About the obtained silica membrane composite, the degree of vacuum of the cell was measured by the following method. The measurement of the degree of vacuum of the cell is for evaluating whether or not the silica film is well formed on the surface of the cell of the porous substrate. The measurement of the degree of vacuum of the cell was performed for each cell as shown in FIGS. FIG. 4 is a schematic diagram for explaining a method of measuring the degree of vacuum of the cell. FIG. 5 is an enlarged schematic view showing one cell in FIG. 4 in an enlarged manner.

  As shown in FIG.4 and FIG.5, the plug member 40 is arrange | positioned in the opening part of the cell 2 of the one end surface 11 and the other end surface 12 of a porous base material. The plug member 40 plugs the opening of the cell 2 on one end face 11 and the other end face 12 in an airtight state. For example, as the plug member 40, a silicon plug can be used. The needles 44 are passed through the plug members 40 provided at both ends of the cell 2. The needle 44 shown in FIG. 5 has a hollow cylindrical shape with a sharp tip. Alternatively, the needle 44 may be passed through the plug member 40 first, and the plug member 40 may be disposed in the opening of the cell 2. The needle 44 penetrating the plug member 40 on the one end face 11 side of the porous substrate is connected to a pipe 43, and the pipe 43 is further connected to the vacuum pump 41. The needle 44 penetrating the plug member 40 on the other end face 12 side of the porous substrate is connected to a pipe 43, and the pipe 43 is further connected to a pressure gauge 42.

  The vacuum pump 41 is started and the piping 43 and the cell 2 are evacuated. The pressure in the evacuated state is measured by the pressure gauge 42. When a ceramic film is formed on the entire surface of the cell 2 of the porous substrate 10, a vacuum state of about -90 kPa can be maintained. On the other hand, when a ceramic film is not formed on a part of the surface of the cell 2 of the porous substrate 10, air flows from a portion where the ceramic film is not formed, and the vacuum state cannot be maintained. .

  In the silica membrane composite produced in Example 1, 34 cells are formed in one direction extending so as to pass through the center of the cross section in a cross section perpendicular to the cell extending direction. The measurement of the degree of vacuum of the cell in the silica membrane composite produced according to Example 1 is a multiple of 3 counted from the outermost cell and the cell adjacent to the outermost cell among the 34 cells. A total of 12 cells were used for the cell. 6 is a photograph of one end face of the silica membrane composite produced in Example 1. FIG. In the photograph of FIG. 6, the locations indicated by the numbers 1 to 12 are the measurement locations of the degree of vacuum of the cell. FIG. 7 is a graph showing the measurement results of the cell vacuum degree of the silica membrane composite produced in Example 1. In FIG. 7, the horizontal axis represents the cell position, and the vertical axis represents the degree of vacuum (kPa). “Cell position” means the number of cells to be measured counted from the outermost cell when the outermost cell is 1. “Vacuum degree (kPa)” indicates a gauge pressure.

  In the measurement of the degree of vacuum of the cell, when the degree of vacuum in all the cells is −90 kPa or less, the measurement result is “A”. When the degree of vacuum in at least one cell is −80 to −90 kPa and the degree of vacuum in other cells is −90 kPa or less, the measurement result is “B”. When the degree of vacuum in at least one cell exceeds −80 kPa, the measurement result is “C”. The measurement result is “A”.

(Examples 2 to 5)
Except for changing the diameter of one end face of the porous substrate (mm), the number of cells (pieces), the diameter of the cells (mm), and the amount of the precursor sol used (mL) as shown in Table 1, A silica membrane composite was produced in the same manner as in Example 1. The degree of vacuum of the cell of the obtained silica membrane composite was measured by the same method as in Example 1. The results are shown in Table 1. In addition, about each silica membrane composite obtained in Examples 2-5, in one direction which passes through the center of the section in the section perpendicular to the direction in which the cell extends, the vacuum of the cell is as follows. The degree of measurement was taken. In the silica membrane composite obtained in Example 2, the cell vacuum was applied to a total of 8 cells for the outermost peripheral cell and a multiple of 3 cells counted from the cell adjacent to the outermost peripheral cell. The degree of measurement was taken. In Example 3, the degree of vacuum of the cells was measured for a total of six cells, with respect to the outermost peripheral cell and a multiple of 3 cells counted from the cell adjacent to the outermost peripheral cell. In Example 4, the degree of vacuum of the cells was measured for a total of five cells with respect to the outermost peripheral cell and a cell that is a multiple of 2 counted from the cell adjacent to the outermost peripheral cell. In Example 5, the cell vacuum degree was measured for all the seven cells in the one direction.

  Also in Examples 2 to 5, when the porous substrate was inverted, the free-falling precursor sol was visually observed whether or not it was evenly accumulated on one end surface of the porous substrate. Judged by. The determination criteria are the same as in the first embodiment. The determination result is shown in the column of “deposition result after inversion” in Table 1.

(Comparative Examples 1-5)
In Comparative Examples 1 to 5, the silica film precursor was formed by the method shown in FIG. 17 without performing the ceramic film precursor preparation step A by upside down as shown in FIGS. 3A to 3D. That is, in Comparative Examples 1 to 5, as shown in FIG. 17, the precursor sol 121 stored in the container 120 is poured from the upper part of the porous substrate 110 and passed through the cell 112 of the porous substrate 110. Was done by. In Comparative Examples 1 to 5, “the diameter of one end face of the porous substrate (mm)”, “the length of the porous substrate in the cell extending direction (mm)”, “number of cells (pieces)” Table 2 shows “cell diameter (mm)”, “total open area of cell (mm ² )”, and “area of silica film (m ² )”. Further, “Opening area ratio” and “Amount of precursor sol used (mL)” are shown in Table 2. The degree of vacuum of the cell of the silica membrane composite obtained in Comparative Examples 1 to 5 was measured. The results are shown in Table 2. In each of Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, Example 3 and Comparative Example 3, Example 4 and Comparative Example 4, and Example 5 and Comparative Example 5, the vacuum of each cell. The measurement method is the same.

  FIG. 8 is a graph showing the measurement results of the cell vacuum degree of the silica membrane composite produced in Comparative Example 1. FIG. 9 is a graph showing the measurement results of the cell vacuum degree of the silica membrane composite produced according to Example 2. FIG. 10 is a graph showing the measurement results of the cell vacuum degree of the silica membrane composite produced in Comparative Example 2. FIG. 11 is a graph showing the measurement results of the cell vacuum degree of the silica membrane composite produced according to Example 3. FIG. 12 is a graph showing the measurement results of the cell vacuum degree of the silica membrane composite produced in Comparative Example 3. FIG. 13 is a graph showing the measurement results of the cell vacuum degree of the silica membrane composite produced in Example 4. FIG. 14 is a graph showing the measurement results of the cell vacuum degree of the silica membrane composite produced in Comparative Example 4. FIG. 15 is a graph showing the measurement results of the cell vacuum degree of the silica membrane composite produced according to Example 5. FIG. 16 is a graph showing the measurement results of the cell vacuum degree of the silica membrane composite produced in Comparative Example 5. 8 to 16, the horizontal axis indicates the cell position, and the vertical axis indicates the degree of vacuum (kPa).

(Result 1)
As shown in Tables 1 and 2, in the methods for producing the silica membrane composites of Examples 1 to 5, good results could be obtained in all measurements of the cell vacuum. Moreover, in the manufacturing method of the silica membrane composite of Examples 1-5, the deposition results after inversion were all good. On the other hand, in the method for producing a silica membrane composite of Comparative Examples 1 to 3, in the measurement of the degree of vacuum of the cell, the degree of vacuum of the cell cannot be maintained, and a silica film can be formed over the entire surface of the cell. I couldn't. That is, in a method in which the precursor sol is poured from the upper part of the porous substrate as in the conventional method for producing a silica membrane composite, the cells into which the precursor sol flows are likely to be uneven, and the silica film is spread over the entire surface of the cell. In order to form a higher amount of precursor sol is required. According to the method for producing a ceramic membrane composite of the present invention, it was found that the silica membrane can be satisfactorily formed on the surface of all the cells of the porous substrate at least in the amount of the precursor sol for forming the silica membrane.

  In the production methods of Comparative Examples 4 and 5, a silica film could be formed over the entire surface of the cell. However, considering the results of Examples 1 to 3 and Comparative Examples 1 to 3, in the production methods of Examples 4 and 5, even if the amount of precursor sol used is further reduced, a silica film is formed over the entire surface of the cell. There is a possibility that it can be formed. In Examples 1 to 5, the use of each precursor sol in Examples 1 to 4 is based on the usage amount of the precursor sol of Example 5 in which the diameter of one end face of the porous substrate is the smallest 30 mm. The amount was determined by the open area ratio. In Examples 1 to 5, all the favorable results were obtained in the measurement of the degree of vacuum of the cell, and it can be said that there is still room for reducing the amount of the precursor sol used. On the other hand, when considering the results of Comparative Examples 1 to 5, it is considered that in Comparative Examples 4 and 5, if the amount of precursor sol used is further reduced, a silica film cannot be formed over the entire surface of the cell. That is, in Comparative Examples 4 and 5, no further reduction in the amount used can be expected. Therefore, in the production methods of Comparative Examples 4 and 5, in order to form a silica film satisfactorily over the entire surface of the cell, an excessive amount of precursor sol must be used as compared with Examples 4 and 5. It will not be.

(Examples 6 to 11)
In Examples 6 to 11, a porous substrate in which the diameter (mm) of one end surface of the porous substrate and the number of cells (pieces) are as shown in Table 3 and Table 4 were used, and Example 1 was used. A silica membrane composite was produced by the same method as described above. In Examples 6 to 11, the usage amount (mL) of the precursor sol was changed as shown in Tables 3 and 4.

In Examples 6 to 8, “the diameter of one end face of the porous substrate (mm)”, “the length of the porous substrate in the cell extending direction (mm)”, “the number of cells (pieces)”, Table 3 shows “cell diameter (mm)”, “total open area of cell (mm ² )”, and “area of silica film (m ² )”. In addition, Table 3 shows “amount of precursor sol used (mL)” and “in-cylinder sol height” in Examples 6 to 8. In Examples 9 to 11, “the diameter of one end face of the porous substrate (mm)”, “the length of the porous substrate in the cell extending direction (mm)”, “the number of cells (pieces)”, “Cell diameter (mm)”, “total open area of cell (mm ² )”, and “area of silica film (m ² )” are shown in Table 4. Table 4 shows “amount of precursor sol used (mL)” and “in-cylinder sol height” in Examples 9 to 11.

  Also in Examples 6 to 11, when the porous substrate was inverted, the free-falling precursor sol was visually observed on the one end surface of the porous substrate. Judged by. The determination criteria are the same as in the first embodiment. The determination results are shown in the “deposition result after inversion” column of Tables 3 and 4.

Moreover, about Examples 9-11, the pervaporation test of E10 gasoline and the pervaporation test of benzene / cyclohexane were done with the following method. The results of the pervaporation test of E10 gasoline are shown in the columns of “ethanol concentration (volume%)” and “ethanol permeation amount (kg / m ² · h)” in Table 4. The results of pervaporation test of benzene / cyclohexane are shown in the columns of “benzene concentration (mass%)” and “benzene permeation amount (kg / m ² · h)” in Table 4.

(E10 gasoline pervaporation test)
E10 gasoline having a temperature of 70 ° C. was circulated in the cells of the silica membrane composites (ceramic membrane composites) of Examples 9 to 11, and the pressure was reduced from the side surface of the porous substrate at a vacuum degree of −75 kPa (gauge pressure). To do. And the permeation | transmission vapor | steam from the side surface of a porous base material was collected with the trap cooled with liquid nitrogen. From the mass of the collected liquefied permeate vapor and the results of gas chromatographic analysis of the liquefied permeate vapor, the ethanol concentration (% by volume) and the ethanol permeation amount (kg / m ² · h) of the permeated vapor were calculated. Asked. “E10 gasoline” is gasoline mixed with 10% ethanol.

(Pervaporation test of benzene / cyclohexane)
A benzene / cyclohexane mixed liquid [benzene: cyclohexane = 50: 50 (mass ratio)] at a temperature of 50 ° C. was circulated in the cells of the silica membrane composites (ceramic membrane composites) of Examples 9 to 11, and was porous. The pressure is reduced from the side surface of the substrate at a vacuum degree of -95 kPa (gauge pressure). And the permeation | transmission vapor | steam from the side surface of a porous base material was collected with the trap cooled with liquid nitrogen. From the mass of the collected liquefied product of the permeated vapor and the results of gas chromatography analysis of the liquefied product of the permeated vapor, the benzene concentration (% by mass) and the amount of benzene permeated (kg / m ² · h) Asked.

(Result 2)
As shown in Tables 3 and 4, in Examples 7, 8, 10 and 11 where the in-cylinder sol height was 2 cm or more, the deposition result after inversion was A. That is, it was confirmed that the precursor sol was evenly accumulated on one end face of the porous substrate. In Examples 6 and 9, the amount of the precursor sol used was less than that in Examples 7, 8, 10 and 11, so that the liquid level of the precursor sol was not uniform. However, also in Examples 6 and 9, it was possible to freely drop the precursor sol over the entire area of one end face of the porous substrate. In the method for producing a ceramic membrane composite of the present invention, when the area of one end face of the porous substrate is Scm ² and the amount of precursor sol used is 2 SmL or more, better film formation It was found possible to do. As can be seen from the results of the pervaporation test of E10 gasoline, the silica membrane composites of Examples 9 to 11 were capable of separating or concentrating ethanol well. In particular, the silica membrane composites of Examples 10 and 11 in which the usage amount of the precursor sol is 2 SmL or more has a high ethanol concentration (volume%) of the permeated vapor, and can be separated or concentrated better. there were. Further, as can be seen from the results of the benzene / cyclohexane pervaporation test, the silica membrane composites of Examples 9 to 11 were able to separate or concentrate benzene well.

(Examples 12 to 14)
In Examples 12 to 14, the diameter (mm) of one end face of the porous substrate and the number of cells (pieces) were as shown in Table 5 using the porous substrate as shown in Table 5. A silica membrane composite was produced in the same manner as in Example 1 except that the top-and-bottom inversion was performed at “reversal speed (m / sec)”. In Examples 12 to 14, “the diameter of one end face of the porous substrate (mm)”, “the length of the porous substrate in the cell extending direction (mm)”, “the number of cells (pieces)”, “Cell diameter (mm)”, “total open area of cell (mm ² )”, and “area of silica film (m ² )” are shown in Table 5. Table 5 shows “amount of precursor sol used (mL)” and “in-cylinder sol height (cm)” in Examples 12 to 14. In Examples 12 to 14, in the case where the area of one end face of the porous substrate was Scm ^2, the amount of precursor sol is 2SmL.

  The “reversal speed (m / sec)” is the precursor of the precursor sol storage container when the porous substrate is rotated 180 ° so that the top and bottom of one end surface and the other end surface are reversed. It is the velocity (m / sec) of the sol liquid surface part.

  Also in Examples 12 to 14, it was visually determined whether or not the precursor sol that had fallen freely was evenly accumulated on one end surface of the porous substrate when the porous substrate was inverted. Judged. The determination criteria are the same as in the first embodiment. The determination results are shown in the column “Deposition results after inversion” in Table 5.

(Result 3)
As shown in Table 5, in Examples 12 and 13, the deposition result after inversion was A. That is, it was confirmed that the precursor sol was evenly accumulated on one end face of the porous substrate. As shown in Example 14, when the reversal speed was low, the liquid level of the precursor sol that had fallen freely did not become uniform.

(Examples 15 to 18)
In Examples 15-18, the diameter (mm) of one end surface of the porous substrate and the number of cells (pieces) were the same as in Example 1 using the porous substrate as shown in Table 6. A silica membrane composite was produced by this method. In Examples 15 to 18, the ceramic film precursor preparation step A was performed using a precursor sol having “sol concentration (mass%)” and “viscosity (mPa · s)” as shown in Table 6. It was. In Examples 15 to 18, “the diameter of one end face of the porous substrate (mm)”, “the length of the porous substrate in the cell extending direction (mm)”, “the number of cells (pieces)”, “Cell diameter (mm)”, “total open area of cell (mm ² )”, and “area of silica film (m ² )” are shown in Table 6. Table 6 shows “amount of precursor sol used (mL)” and “in-cylinder sol height (cm)” in Examples 15 to 18. In Example 15-18, in the case where the area of one end face of the porous substrate was Scm ^2, the amount of precursor sol is 2SmL.

The “sol concentration (mass%)” is the ratio of the mass in terms of SiO ₂ of the silica sol in the precursor sol to the total mass of the precursor sol. The “viscosity (mPa · s)” is a value measured with a conical rotational viscometer.

  Also in Examples 15 to 18, it was visually determined whether or not the precursor sol that had fallen freely was evenly accumulated on one end surface of the porous substrate when the porous substrate was inverted. Judged. The determination criteria are the same as in the first embodiment. The determination result is shown in the column of “deposition result after inversion” in Table 6.

(Result 4)
As shown in Table 6, in Examples 15 to 18, the deposition result after inversion was A. That is, when the viscosity of the precursor sol was 1.0 to 20 mPa · s, it was confirmed that the precursor sol was evenly accumulated on one end face of the porous substrate.

(Examples 19 to 22)
In Examples 19 to 22, the diameter (mm) of one end face of the porous substrate and the number of cells (pieces) were as shown in Table 7 using the porous substrate as shown in Table 7. A ceramic membrane composite was produced in the same manner as in Example 1 except that the precursor sol was used. In the column of “Sol Type” in Table 7, the type of precursor sol used in Examples 19 to 22 is shown.

  “Silica” in Example 19 is a sol for forming a silica film using tetraethoxysilane as an alkoxide. “Titania” of Example 20 is a sol for forming a titania film using titanium tetraisopropoxide as an alkoxide. “Zirconia” in Example 21 is a sol for forming a zirconia film using zirconium tetraethoxide as an alkoxide. The “p-tolyl group-containing silica” in Example 22 is a precursor sol of the same type as the precursor sol used in Example 1.

In Examples 19 to 22, “the diameter of one end face of the porous substrate (mm)”, “the length of the porous substrate in the cell extending direction (mm)”, “the number of cells (pieces)”, “Cell diameter (mm)”, “total open area of cell (mm ² )”, and “area of ceramic membrane (m ² )” are shown in Table 7. Table 7 shows the “opening area ratio”, “precursor sol usage (mL)”, and “in-cylinder sol height (cm)” in Examples 19 to 22.

  In Examples 19-22, the degree of vacuum of the cell was measured by the same method as Example 1 about each obtained ceramic membrane composite. The measurement results are shown in the column “Measurement results of vacuum degree of cell” in Table 7.

(Result 5)
As shown in Table 7, a ceramic film could be formed satisfactorily with any of the precursor sols used in Examples 19-22. That is, it was found that the method for producing a ceramic membrane composite of the present invention can be suitably used as a method for producing a ceramic membrane composite having various ceramic membranes such as a silica membrane, a titania membrane, and a zirconia membrane. .

  The present invention can be used as a method of manufacturing a ceramic membrane composite for separating or concentrating only a specific type of material from a fluid in which a plurality of types of materials are mixed.

2: cell, 10: porous substrate, 11: one end face, 12: the other end face, 20: container for storing precursor sol, 20a: liquid outlet, 21: precursor sol, 25: ceramic film precursor , 26: Ceramic membrane, 28: Container for collecting precursor sol, 28a: Liquid recovery port, 40: Plug member, 41: Vacuum pump, 42: Pressure gauge, 43: Pipe, 44: Needle, 100: Ceramic membrane composite 110: porous substrate, 112: cell, 120: container, 121: precursor sol, 124: cylindrical member, O: center of rotation.

Claims (8)

A precursor sol for forming a ceramic film is applied to the surface of the cell of a cylindrical porous base material on which a plurality of cells extending from one end surface to the other end surface serving as a fluid flow path are formed. A ceramic film precursor preparation step for forming a film precursor;
Heat-treating the ceramic film precursor to form a ceramic film on the surface of the cell of the porous substrate, and
A precursor sol storage container having a liquid outlet having a larger opening than the region where the cells are formed on the one end face of the porous base material in the ceramic film precursor preparation step, The porous base material provided on the one end face side of the porous base material, and the precursor sol storage container is provided on the porous base material cell. In a state where the extending direction is a vertical direction, the precursor sol stored in the precursor sol storage container is directed from the entire liquid discharge port toward the one end surface of the porous substrate. A method for producing a ceramic membrane composite, wherein the ceramic membrane precursor is formed by free-falling.   The porous substrate in which the precursor sol storage container in which the precursor sol is stored is disposed on the one end surface side, and the direction in which the one end surface is downward and the cells of the porous substrate extend is 180 ° so that the top and bottom of the one end face and the other end face of the porous base material are reversed with the one point in the cell extending direction as the rotation center from the state of being arranged in the vertical direction. The manufacturing of the ceramic membrane composite according to claim 1, wherein the precursor sol stored in the precursor sol storage container is allowed to freely fall toward the one end surface of the porous substrate by rotating. Method.   When the length from the rotation center to the liquid level accumulated in the precursor sol storage container is a (m), the porous substrate is rotated 180 ° so that the top and bottom are reversed. The method for producing a ceramic membrane composite according to claim 2, wherein the velocity of the precursor sol liquid surface portion is √ (9.8a) m / sec or more. The amount of the precursor sol stored in the precursor sol storage container is ² SmL or more when the area of the one end face of the porous substrate is Scm ^2. A method for producing a ceramic membrane composite according to claim 1.   The method for producing a ceramic membrane composite according to any one of claims 1 to 4, wherein an outer diameter of the one end face of the porous substrate is 50 mm or more.   The method for producing a ceramic membrane composite according to claim 1, wherein the precursor sol has a viscosity of 1.0 to 20 mPa · s.   The method for producing a ceramic membrane composite according to any one of claims 1 to 6, wherein the ceramic membrane is a silica membrane.   The method for producing a ceramic membrane composite according to claim 7, wherein the silica membrane is a silica membrane containing a p-tolyl group.