JP5703503B2 - Method for producing porous structure - Google Patents

Description

The present invention relates to a method for producing a porous structure, and is useful when applied to a reaction in contact with a fluid.

  Conventionally, a porous body in which a metal, a metal oxide, or the like is coated on the surface of the porous body is known. The porous body is formed after appropriately selecting a metal or metal oxide used for coating according to the application. For example, a porous body coated with a metal oxide is used for gas purification that adsorbs and removes impurities contained in a combustible gas.

  As an example of such a porous body, the surface of the foam metal is coated with a mixture of titanium oxide and silica, and an aggregate made of a mixture of titanium oxide and silica is inserted and held inside the cell of the foam metal. A known hydrophilic foam metal body is known (for example, see Patent Document 1).

  This hydrophilic foam metal body was held in cells (pores) formed in the foam metal by making the ratio of the voids on the outermost surface of the foam metal different from the ratio of the voids inside the foam metal. Agglomeration is prevented from falling off. Moreover, since the silica of an aggregate has the effect | action which adheres to the whole surface inside a cell, it has the structure by which an aggregate is hold | maintained in a cell.

  However, since the aggregate is inserted into the foam metal cell from the outside, a cell having an opening diameter larger than the diameter of the aggregate necessarily exists. Therefore, there is a possibility that aggregates may fall out of the cell due to physical impact. In addition, the aggregate or the foam metal may expand or contract due to a rapid temperature change, or the composition or the aggregate or the foam metal may change or contract due to a chemical reaction. Thus, the conventional hydrophilic foam metal bodies cannot completely prevent the aggregates from falling out of the cells. Moreover, coating | covers, such as a titanium oxide and a silica, may peel by distribute | circulating a fluid to a hydrophilic foam metal body for a long time. In this case, not only the catalytic action of the coating by titanium oxide or silica is lost, but also the action of fixing the aggregates is lost, and the aggregates are more likely to fall out of the cell.

JP 2011-1111643 A

In view of such circumstances, an object of the present invention is to provide a method for producing a porous structure that can reliably prevent the particles having functionality held in a cell from falling off.

A first aspect for achieving the above object is a porous body formed by contacting a fluid to exhibit a desired function and sintering the material, and a group consisting of a metal oxide, a metal, and carbon. Particles made of a functional material selected and exhibiting the desired function, and the porous body includes a plurality of cells having an opening diameter smaller than the diameter of the particles, and one surface of the porous body. A method for producing a porous structure having a communicating hole formed by connecting the cells to the other surface, wherein the particles are held in the cells, wherein the particles are covered with a spacer material, and the spacers In the method for producing a porous structure, a sintered body is formed by mixing a material with powder formed from the functional material and sintering, and the spacer material is removed.

In the first aspect, it is possible to manufacture a porous structure that can reliably prevent the particles having the functionality held in the cell from falling off by a simple method.

According to a second aspect of the present invention, in the method for manufacturing a porous structure according to the first aspect, the spacer material is an alkali metal compound, and the alkali metal is sintered when the sintered body is sintered. The compound is melted and removed by washing with water.

In the second aspect, the porous structure can be produced by a simpler method.

The third aspect of the present invention is selected from the group consisting of a porous body formed by sintering a material, a porous body formed by contacting a fluid and exhibiting a desired function, Particles made of a functional material that exhibits a desired function, and the porous body includes a plurality of cells having an opening diameter smaller than the diameter of the particles, and one surface to the other surface of the porous body. A method for producing a porous structure having a communication hole formed by connecting cells, wherein the particles are held in the cell, wherein the template material has a large number of cells defined by partition walls. the particles mixed in the partition wall, removing the template material causes sintering the slurry by impregnating a slurry containing powder which is formed from the functional material into the template material, heating said template material To do In the manufacturing method of a porous structure characterized.

In the third aspect, a porous structure that can reliably prevent the particles having functionality held in the cell from falling off can be produced by a simple method.

According to a fourth aspect of the present invention, in the method for producing a porous structure according to the third aspect, the template material is a polyurethane formed by mixing the particles, and the slurry is impregnated. In the method of manufacturing a porous structure, the polyurethane is melted and removed when the template material is heated.

In the fourth aspect, the porous structure can be produced by a simpler method.
Furthermore, as another aspect, by compressing a porous body including closed pore cells, the cells may be communicated to form open pores. In this aspect, a plurality of cells that are closed pores are provided in the porous structure, and when the cells are compressed, communication holes that communicate with each cell are formed, and fluid can come into contact with particles through the communication holes. For example, it is possible to prevent the particles from coming into contact with outside air until the porous structure is transported to the site where it is actually used. The particles can only come into contact with the fluid by compressing at the site. Thereby, it is possible to prevent the function of the particles from being chemically reacted before being transported to the site.

According to the method for producing a porous structure of the present invention, it is possible to reliably prevent the functional particles retained in the cell from falling off.

1 is a cross-sectional view illustrating a schematic configuration of a porous structure according to Embodiment 1. FIG. It is sectional drawing to which a part of FIG. 1 was expanded. 3 is a cross-sectional view showing a method for manufacturing a porous structure according to Embodiment 1. FIG. 3 is a cross-sectional view showing a method for manufacturing a porous structure according to Embodiment 1. FIG. It is sectional drawing to which the schematic structure of the porous structure which concerns on Embodiment 2, and its one part were expanded.

<Embodiment 1>
FIG. 1 is a cross-sectional view showing a schematic configuration of a porous structure according to the present embodiment. FIG. 2 is an enlarged cross-sectional view of a part of FIG.

  As shown in FIGS. 1 and 2, the porous structure 1 according to this embodiment includes a porous body 2 and particles 4 held in the cell 3. The porous structure 1 is used, for example, as a catalyst or a filter, or as one that exhibits a heat exchange function. The function of the porous structure 1 is realized by forming the particles 4 with a functional material that functions as a catalyst or the like. As will be described later, the porous body 2 itself may be formed of a functional material.

  The overall shape of the porous structure 1 is not particularly limited, and is a shape according to the application. For example, when used as a filter for removing impurities in the fluid, it is formed in a flat plate shape that crosses the flow path 10 through which the fluid flows.

  The particle | grains 4 are the granular things formed from the functional material. The shape of the particle 4 is not particularly limited and will be described in detail later. The particle 4 is held inside the cell 3 (may be fixed to the inner surface of the cell 3), and the size is from the inside of the cell 3 to the outside. So that it is not discharged.

  The functional material is at least one selected from the group consisting of metal oxides, metals and inorganics. These are appropriately selected depending on the use of the porous structure 1. Examples of metals include nickel (Ni), copper (Cu), iron (Fe), vanadium (V), tungsten (W), titanium (Ti), cobalt (Co), tin (Sn), magnesium (Mg) , Ruthenium (Ru), palladium (Pd), zinc (Zn), zirconium (Zr), platinum (Pt), gold (Au), silver (Ag), and the like. An alloy consists of two or more of these metals.

  The metal oxide is a compound oxide in which the above metals are oxidized or a composite oxide in which two or more of these metals are oxidized. Other metal oxides include single oxides such as silica and alumina, or mullite, zeolite, bentonite, ceolite, attapulgite, sillimanite, kaolin, sericite, diatomaceous earth, feldspar, glazed clay, silicate compounds Pearlite, vanamiculite, sericite, etc.), or a combination comprising at least one of the foregoing. Moreover, carbon can be mentioned as an inorganic substance.

  The porous body 2 refers to a structure having innumerable minute cells 3 (pores) inside, and further connecting these cells 3 from one surface to the other surface to form a communication hole. As the material of the porous body 2, the above-described functional material can be used.

  1 and 2 show a spherical structure as an ideal cell 3 structure. In the plurality of cells 3, adjacent cells 3 are connected to each other. The insides of adjacent cells 3 communicate with each other through a connection port 5 that is an opening in which the cells 3 are connected. That is, most cells 3 of the porous body 2 are open pores. When the cells 3 communicate with each other, a large number of communication holes serving as fluid flow paths as shown by arrows in FIG. 2 are formed. Note that not all cells 3 need to be open cells. It may be a porous body 2 partially including cells (closed pores) not communicating with the outside.

  The cell 3 is a pore formed in the porous body 2 and has a space large enough to hold the particles 4 therein. However, the particles 4 do not have to be held inside all the cells 3 included in the porous body 2. Further, the porosity of the porous body 2 is not particularly limited, but it is preferable to set the porosity so that the amount of particles 4 that can sufficiently exhibit the function according to the use of the porous structure 1 can be held. The porosity is the ratio of the volume of the space occupied by the cells 3 to the volume of the porous body 2.

  The cell 3 has one or more connection ports 5 connected to the adjacent cells 3. The opening diameter of the connection port 5 is smaller than the diameter of the particles 4 held inside the cell 3. In other words, the particles 4 held inside the cell 3 do not escape from the connection port 5 to the outside.

  However, the opening diameters of all the connection ports 5 included in the cell 3 are not necessarily smaller than the particles 4. For example, a certain cell 3 may be provided with a connection port 5 having an opening diameter larger than that of the particle 4, and the particle 4 can move to the other cell 3 side through such a connection port 5. May be. Finally, in any one of the cells 3, a connection port 5 having an opening diameter smaller than that of the particle 4 (or an opening appearing on the outer surface of the porous body 2 (hereinafter referred to as an external opening)) is provided. It is only necessary that the particles 4 do not move outside the cell 3 from the connection port 5 (or external opening).

  By holding the particles 4 inside the cells 3 having such connection ports 5 (or external openings), the particles 4 are prevented from coming out of the cells 3 of the porous body 2.

  In the porous structure 1, fluid is circulated from one surface to the other surface through the communication holes. The fluid is brought into contact with the surface of the porous body 2 or the surface of the particles 4, and a chemical reaction or heat exchange is performed according to the functional material forming the porous body 2 and the particles 4. Function is demonstrated.

  As described above, the particles 4 are prevented from coming out of the cells 3 of the porous body 2 to the outside. Therefore, the porous structure 1 according to the present embodiment can prevent the fluid from flowing out of the cell 3 of the porous body 2 together with the fluid even if the fluid flows.

  If the functional material is simply coated on the surface of the porous body 2, the coated functional material may be peeled off together with the fluid. However, according to the present invention, since the particles 4 formed from the functional material are physically held in the porous body 2, the porous structure 1 in which the functionality is maintained for a long time is provided. The

  Moreover, the porous structure 1 can form each of the porous body 2 and the particle | grains 4 with a different functional material. According to this, two types of catalytic actions can be realized simultaneously in one porous structure 1. Furthermore, with such a configuration, in the porous structure 1 according to the present invention, one type of functional material occupies the entire surface of the porous body 2, and the other type of functional material includes all the surfaces of the particles 4. Can occupy. That is, the porous structure 1 can sufficiently secure the contact area of various functional materials as compared with the case where two types of functional materials are applied to the porous body 2 without using the particles 4.

  Furthermore, as a characteristic of the porous structure 1, the ability to hold a liquid is higher than that of the porous body 2 that does not hold the particles 4. That is, the liquid is held on the surfaces and gaps of the porous body 2 and the particles 4, and the liquid is well held as the entire porous structure 1. Thereby, for example, the liquid includes a main compound that reacts with the fluid, and the porous structure 1 that causes the particles 4 to act as a catalyst for the reaction can be configured.

  For example, the use of the porous structure 1 can include a filter that removes impurities contained in a combustible gas obtained by pyrolyzing biomass or the like. In this case, the porous structure 1 is preferably one in which particles 4 made of ceramic such as zirconia are held in the cells 3 of the porous body 2 made of foamed metal obtained by foaming a metal. The porous structure 1 is impregnated with molten carbonate.

  Thereby, impurities are suitably removed by the molten carbonate and the particles 4 acting as a catalyst. As described above, the porous structure 1 holds the molten carbonate satisfactorily, so that the molten carbonate is not easily spilled even when a fluid flows. For this reason, the porous structure 1 maintains the impurity removal function for a long time.

The impurities contained in the combustible gas include sulfur (S), halogen (F, Cl), and nitrogen (N). From these elements, hydrogen sulfide (H ₂ S) is used in a high-temperature reducing atmosphere. ), Hydrogen chloride (HCl), hydrogen fluoride (HF), ammonia (NH ₃ ), and the like. As the molten carbonate, lithium carbonate _(Li 2 _CO 3), sodium carbonate _(Na 2 _CO 3), those various alkali metal carbonate such as potassium carbonate _(K 2 CO _3), and either alone or mixed Can be used. In addition to the alkali metal carbonates, carbonates such as magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and cerium (Ce) can be used as the molten carbonate. .

  Moreover, heat exchange can be mentioned as another use of the porous structure 1. For example, the specific heat of the particles 4 is made higher than that of the porous body 2. Then, the fluid is circulated through the porous structure 1. As a result, the particles 4 can retain heat for a longer time than the porous body 2.

  In the embodiment described above, the particles 4 are formed of a functional material and are allowed to react with a fluid. However, the present invention is not limited to such a mode. The porous body 2 may be formed of a functional material and reacted with a fluid, or both the particles 4 and the porous body 2 may be formed of a functional material and reacted with a fluid. It is good.

  Here, the manufacturing method of the porous structure 1 is demonstrated. FIG. 3 is a cross-sectional view showing a method for manufacturing a porous structure according to the present embodiment.

  First, as shown in FIG. 3A, the periphery of the particles 4 is covered with a spacer material 6. The spacer material 6 is preferably melted by heating, and for example, an alkali metal compound is preferable. Examples of the alkali metal compound include sodium chloride, potassium chloride, sodium carbonate, potassium carbonate and the like.

  Next, as shown in FIG. 3B, the powdery functional material forming the porous body 2 and the particles 4 covered with the spacer material 6 are mixed and molded into a predetermined shape. For example, the particles 4 and the metal powder are mixed at a ratio such that a desired porosity is obtained, and formed into a flat plate shape.

  And as shown in FIG.3 (c), the shape | molded mixture is sintered. The spacer material 6 is melted by heating by this sintering, and is removed by washing with water. Thereby, the region where the spacer material 6 originally existed becomes the cell 3, and the porous structure 1 in which the particles 4 are held inside the cell 3 is formed. The portion where the adjacent spacer materials 6 are in contact with each other is the connection port 5 between the cells 3.

  A manufacturing method of the porous structure 1 different from the manufacturing method described above will be described. FIG. 4 is a cross-sectional view showing a method for manufacturing a porous structure according to the present embodiment.

  First, as shown in FIG. 4A, a template material 7 in which a large number of holes 9 (open pores and closed pores) are defined is prepared. Particles 4 are mixed in the portion (partition wall) that defines the holes 9 of the template material 7. The template material 7 is preferably porous and melted by heating, and examples thereof include a material in which polyurethane is formed in a porous shape (urethane foam). Specifically, it is formed by mixing particles 4 together with a foaming agent into a polyurethane raw material and foaming.

  Next, as shown in FIG. 4B, the template material 7 is impregnated with a slurry 8 obtained by slurrying the powdery functional material forming the porous body 2. Thereby, the slurry 8 is held in the holes 9 of the template material 7.

  Then, as shown in FIG. 4C, the template material 7 impregnated with the slurry 8 is dried and heated. As a result, the template material 7 is melted and removed to form the porous structure 1. As shown in FIG. 4 (d), the porous structure 1 according to this manufacturing method is such that the powdery functional material is sintered in the pore 9 portion of the template material 7, and the gap Becomes the cell 3 and the particles 4 are held in the cell 3. In this case, the part where the template material 7 (partition wall) was originally located becomes a gap and becomes the connection port 5 between the cells 3.

  According to the manufacturing method of the porous structure 1 demonstrated above, the porous structure 1 which can prevent reliably the particle | grains which have the functionality hold | maintained in the cell falling off can be manufactured by a simple method. .

<Embodiment 2>
Although the porous structure 1 which concerns on Embodiment 1 was set as the structure which the cell 3 connected to the exterior, it is not necessarily limited to such an aspect. FIG. 5 is an enlarged cross-sectional view of a schematic configuration of a porous structure according to the present embodiment and a part thereof. In addition, the same code | symbol is attached | subjected to the same thing as Embodiment 1, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 5A, the porous structure 1 according to this embodiment includes a porous body 2 and particles 4 held in the cell 3.

  The porous body 2 has innumerable minute cells 3 (pores) inside, and these cells 3 are formed as closed pores (closed cells). As the material of the porous body 2, the above-described functional material can be used. However, not all cells 3 need to be closed pores. The porous body 2 may include some open pores as in the first embodiment.

  FIG. 5A shows a spherical structure as an ideal cell 3 structure. The plurality of cells 3 are not connected to other adjacent cells 3.

  The cell 3 is a pore formed in the porous body 2 and has a space large enough to hold the particles 4 therein. That is, the particles 4 are confined in the space inside the cell 3.

  When such a porous structure 1 is crushed by, for example, compressing in the vertical direction, a part of the cell 3 is broken and communicates with another cell 3. That is, by compressing, the cell 3 is destroyed and the insides of the adjacent cells 3 communicate with each other. That is, as with the porous structure 1 shown in the first embodiment, most of the cells 3 of the porous body 2 become open pores, and the cells 3 communicate with each other, for example, as shown by the arrow in FIG. A large number of communication holes serving as fluid flow paths are formed.

  The porous structure 1 formed in this way has the same effect as that of the first embodiment. For example, since the opening diameter of the connection port 5 is smaller than the diameter of the particles 4 held inside the cells 3 as in the first embodiment, the particles 4 held inside the cells 3 are connected to each other. It does not come out of the mouth 5 to the outside.

  The porous structure 1 according to the present embodiment is a communication hole in which particles 4 are initially held in the cells 3 as closed pores, and fluid can contact the particles 4 in the cells 3 by compression of the porous structure 1. Is formed. By adopting such a structure, it is possible to prevent the particles 4 from coming into contact with the outside air until the porous structure 1 is transported to the site where it is actually used. And it becomes possible for the particle | grains 4 to contact a fluid only by compressing in the field. Thereby, it can prevent that the particle | grains 4 carry out a chemical reaction before conveying to a spot, and the function will deteriorate.

  The porous structure 1 according to Embodiment 2 can be produced, for example, as follows. First, a slurry in which a powdery functional material forming the porous body 2 is slurried is prepared, and the particles 4 are mixed into the slurry. The porous structure 1 can be manufactured by heating and sintering while injecting bubbles into the slurry (bubbling).

As another manufacturing method, CaCO ₃ , MgCO ₃ or the like is used as a foaming agent, and these are coated on the particles 4. Then, the coated particles 4 are mixed with molten metal. Thereafter, the temperature is raised to a foaming temperature at which the foaming agent foams, and then rapidly cooled, whereby a closed cell is formed in the solid metal, and a porous structure in which the particles 4 are held in the closed cell is obtained.

  According to the manufacturing method of the porous structure 1 demonstrated above, the porous structure 1 which can prevent reliably the particle | grains which have the functionality hold | maintained in the cell falling off can be manufactured by a simple method. .

  The present invention can be used in a catalyst, a filter, and an industrial field requiring heat exchange.

DESCRIPTION OF SYMBOLS 1 Porous structure 2 Porous body 3 Cell 4 Particle 5 Connection port 6 Spacer material 7 Template material 8 Slurry 10 Channel

Claims (4)

In contact with the fluid to perform the desired function,
A porous body formed by sintering the material;
Selected from the group consisting of metal oxides, metals, and carbon, and comprising particles made of a functional material that exhibits the desired function,
The porous body has a plurality of cells having an opening diameter smaller than the diameter of the particles, and communication holes formed by connecting the cells from one surface to the other surface of the porous body,
A method for producing a porous structure in which the particles are held in the cell,
Cover the particles with a spacer material,
A method for producing a porous structure, comprising forming a sintered body by mixing the spacer material with powder formed from the functional material and sintering the powder, and removing the spacer material. In the manufacturing method of the porous structure according to claim 1 ,
The spacer material is an alkali metal compound,
When the sintered body is sintered, the alkali metal compound is melted and removed by washing with water. In contact with the fluid to perform the desired function,
A porous body formed by sintering the material;
Selected from the group consisting of metal oxides, metals, and carbon, and comprising particles made of a functional material that exhibits the desired function,
The porous body has a plurality of cells having an opening diameter smaller than the diameter of the particles, and communication holes formed by connecting the cells from one surface to the other surface of the porous body,
A method for producing a porous structure in which the particles are held in the cell,
The particles are mixed in the partition walls of the template material in which a large number of cells are defined by the partition walls,
Impregnating the template material with a slurry containing powder formed from the functional material;
The method for producing a porous structure, wherein the template material is removed while the slurry is sintered by heating the template material. In the manufacturing method of the porous structure according to claim 3 ,
The template material is a porous polyurethane mixed with the particles,
The method for producing a porous structure, wherein the polyurethane is melted and removed when the template material impregnated with the slurry is heated.

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