Ceramic structures, catalyst composites, and catalyst supports for electric field application

Abstract

This technology provides a ceramic structure that can achieve both an increase in specific surface area and improved gas flowability. [Solution] The ceramic structure has multiple pores, and when the pore diameters of the multiple pores contained in the ceramic structure, measured with a mercury porosimeter, are plotted on the horizontal axis and the log differential pore volume at each pore diameter is plotted on the vertical axis, the following relationships (1) to (3) are satisfied. (1) The first peak is in the range of pore diameter between 100 μm and less than 1000 μm. (2) A second peak is present in the range of pore diameter between 10 μm and less than 100 μm. (3) A third peak is present in the range of pore diameter between 0.1 μm and less than 10 μm.

Description

[Technical Field]

[0001] The present invention relates to ceramic structures, catalyst composites, and catalyst supports for electric field application. [Background technology]

[0002] Ceramic structures with pores have been known for some time (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2020 / 100831 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, even with prior art such as Patent Document 1, there was still room for improvement in techniques that could achieve both improved gas flowability and increased specific surface area in ceramic structures.

[0005] The present invention aims to provide a technology that can achieve both an increase in specific surface area and improved gas flowability in a ceramic structure. [Means for solving the problem]

[0006] The present invention has been made to solve at least some of the above-mentioned problems and can be realized in the following forms.

[0007] (1) According to one embodiment of the present invention, a ceramic structure is provided. This ceramic structure has a plurality of pores, and when the pore diameters of the plurality of pores contained in the ceramic structure, measured with a mercury porosimeter, are plotted on the horizontal axis and the log differential pore volume at each pore diameter is plotted on the vertical axis, the following relationships (1) to (3) are satisfied. (1) The first peak is in the range of pore diameter between 100 μm and less than 1000 μm. (2) A second peak is present in the range of pore diameter between 10 μm and less than 100 μm. (3) A third peak is present in the range of pore diameter between 0.1 μm and less than 10 μm.

[0008] This configuration provides pores with peaks of a certain size in three ranges: pore diameters of 100 μm to less than 1000 μm, pore diameters of 10 μm to less than 100 μm, and pore diameters of 0.1 μm to less than 10 μm. This allows for improved gas flow in pores with a diameter of 10 μm to less than 1000 μm, while simultaneously increasing the specific surface area by including pores with a diameter of 0.1 μm to less than 10 μm. Therefore, it is possible to achieve both improved gas flow and increased specific surface area.

[0009] (2) In the ceramic structure of the above form, the log differential pore volume of the first peak may be 0.05 ml / g or more. With this configuration, a certain volume of pores with a pore diameter of 100 μm or more and less than 1000 μm can be present, thereby improving the flowability of gases.

[0010] (3) In the ceramic structure of the above form, the Log differential pore volume of the second peak may be 0.05 ml / g or more. With this configuration, a certain volume of pores with a pore diameter of 10 μm or more and less than 100 μm are present. When the ceramic structure is used as a catalyst support, when the ceramic structure is immersed in a solution containing the catalyst metal, the metal-containing solution spreads throughout the ceramic structure through the pores with a pore diameter of 10 μm or more and less than 100 μm. This allows the catalyst to be supported throughout the ceramic structure.

[0011] (4) In the ceramic structure of the above form, the log differential pore volume of the third peak may be 0.1 ml / g or more. With this configuration, a certain volume of pores with a pore diameter of 0.1 μm or more and less than 10 μm can be present, thereby increasing the specific surface area of ​​the ceramic structure.

[0012] (5) In the ceramic structure of the above form, the ceramic structure may have a three-dimensional network structure. With this configuration, the ceramic structure has a three-dimensional network structure in which multiple ceramic particles are bonded to each other in various directions. Therefore, since multiple pores are formed to face in various directions, the gas flowability can be improved.

[0013] (6) In the ceramic structure of the above form, the ceramic structure may contain cerium oxide as its main component. With this configuration, the ceramic structure contains cerium oxide as its main component. This improves the ionic conductivity of the ceramic structure.

[0014] (7) In the ceramic structure of the above form, the ceramic structure may have a porosity of 60% or more and 93% or less. With this configuration, the porosity of the ceramic structure is 60% or more and 93% or less. As a result, the ceramic structure can suppress pressure loss while simultaneously improving gas flowability and increasing the specific surface area.

[0015] (8) In the ceramic structure of the above form, the cumulative pore volume of the pores with a diameter of 0.1 μm or more and less than 10 μm among the plurality of pores may be 35% or more and 65% or less of the cumulative pore volume of the plurality of pores. With this configuration, the ceramic structure has pores with relatively small diameters. This makes it possible to further increase the specific surface area of ​​the ceramic structure.

[0016] (9) In the ceramic structure of the above form, the number of cells in the ceramic structure may be 5 to 50 per 25.4 mm. With this configuration, the number of cells in the ceramic structure is 5 to 50 per 25.4 mm, and it has a structure that allows gas to flow easily. As a result, the ceramic structure can suppress pressure loss while simultaneously improving gas flowability and increasing the specific surface area.

[0017] (10) In the ceramic structure of the above form, the ceramic structure has a bulk density of 0.5 g / cm³ 3 More than 2.8g / cm 3 The following is also acceptable. According to this configuration, the bulk density of the ceramic structure is 0.5 g / cm³. 3 More than 2.8g / cm 3 The structure is as follows, and has a structure that facilitates gas flow. As a result, the ceramic structure can suppress pressure loss while simultaneously improving gas flowability and increasing the specific surface area.

[0018] (11) The ceramic structure of the above form may further comprise a ceramic foam and a covering portion that covers the ceramic foam. With this configuration, the ceramic structure comprises a covering portion that covers the ceramic foam. As a result, the specific surface area of ​​the ceramic structure is the sum of the specific surface area of ​​the ceramic foam and the specific surface area of ​​the covering portion, and is therefore larger than the specific surface area of ​​the ceramic foam alone. Therefore, it is possible to increase the specific surface area and improve the gas flowability while maintaining a certain level of strength with the ceramic foam.

[0019] (12) In the ceramic structure of the above form, when the pore diameters of the plurality of pores contained in the ceramic structure, measured by a mercury porosimeter, are plotted on the horizontal axis and the log differential pore volume at each pore diameter is plotted on the vertical axis, the following relationship (4) may be satisfied. (4) A fourth peak is present in the range of pore diameter between 0.01 μm and less than 0.1 μm. According to this configuration, regarding the pores, there is a peak having a certain size within the range where the pore diameter is 0.01 μm or more and less than 0.1 μm. Thereby, the specific surface area can be further increased. Therefore, it is possible to achieve both an improvement in gas fluidity and an increase in the specific surface area.

[0020] (13) In the ceramic structure of the above form, the Log differential pore volume of the fourth peak may be 0.1 ml / g or more. According to this configuration, since there is a certain volume of pores with a pore diameter of 0.01 μm or more and less than 0.1 μm, the specific surface area can be further increased.

[0021] (14) According to another form of the present invention, a catalyst composite is provided. This catalyst composite includes the above ceramic structure and a catalyst supported on the ceramic structure and formed of a metal. According to this configuration, in the catalyst composite, a catalyst formed of a metal is supported on the above ceramic structure having a relatively large specific surface area. Thereby, since the catalyst composite includes a relatively large amount of catalyst, the performance of the catalyst can be improved.

[0022] (15) According to still another form of the present invention, a catalyst carrier for electric field application is provided. This catalyst carrier for electric field application includes the above ceramic structure. According to this configuration, since the catalyst carrier for electric field application includes the above ceramic structure having a relatively large specific surface area, it can support a large amount of catalyst. Therefore, the catalyst carrier for electric field application can easily exhibit the performance of the supported catalyst.

[0023] Note that the present invention can be realized in various forms. For example, it can be realized in the form of a method for manufacturing a ceramic structure, a method for manufacturing a catalyst composite, a method for manufacturing a catalyst carrier for electric field application, an apparatus including a ceramic structure, a control method for an apparatus including a ceramic structure, a computer program for causing a computer to execute the manufacture of a ceramic structure, a server device for distributing the computer program, a non-transitory storage medium storing the computer program, etc. [Brief explanation of the drawing]

[0024] [Figure 1] This is a diagram showing the overall structure of the ceramic structure according to the first embodiment. [Figure 2] This figure shows a cross-section of the ceramic structure according to the first embodiment. [Figure 3] This is the first figure illustrating the features of the ceramic structure of the first embodiment. [Figure 4] This is a second figure illustrating the features of the ceramic structure of the first embodiment. [Figure 5] This diagram illustrates the schematic configuration of a reaction apparatus equipped with the catalyst complex of the first embodiment. [Figure 6] This is a flowchart illustrating the manufacturing method of the ceramic structure according to the first embodiment. [Figure 7] This diagram illustrates the results of evaluation tests related to the manufacturing method of ceramic structures. [Figure 8] This is the first diagram illustrating the sample used in the evaluation test. [Figure 9] This is the second diagram illustrating the sample used in the evaluation test. [Figure 10] This is a first enlarged view of the ceramic structure of the second embodiment. [Figure 11] This is a second enlarged view of the ceramic structure of the second embodiment. [Figure 12] The first figure shows the results of image processing on the boundary setting sample. [Figure 13] The second figure shows the results of image processing on the boundary setting sample. [Figure 14] This is a third enlarged view of the ceramic structure of the second embodiment. [Figure 15] This is the first figure illustrating the features of the ceramic structure of the second embodiment. [Figure 16] This is a second figure illustrating the features of the ceramic structure of the second embodiment. [Figure 17]This is a flowchart illustrating the manufacturing method of the ceramic structure according to the second embodiment. [Modes for carrying out the invention]

[0025] <First Embodiment> Figure 1 shows the overall structure of the ceramic structure of the first embodiment. Figure 2 shows a cross-sectional image of the ceramic structure 1 of this embodiment. Figure 2 is an image of a part of the cross-section of the ceramic structure 1 taken at 30x magnification using a scanning electron microscope (SEM). As shown in Figure 1, the ceramic structure 1 of this embodiment is a porous body having a three-dimensional network structure formed of ceramics.

[0026] The ceramic structure 1 is formed from a plurality of ceramic particles 100. The ceramic particles 100 forming the ceramic structure 1 of this embodiment mainly contain cerium oxide (CeO2). Here, "the ceramic particles 100 mainly contain cerium oxide" means that the molar concentration of cerium oxide in the ceramic particles 100 is 50 mol% or more. The ceramic particles 100 of this embodiment are doped with alkaline earth metals and rare earth elements. Calcium is an example of an alkaline earth metal doped into the ceramic particles 100. Gadolinium (Gd), lanthanum (La), yttrium (Y), and the like are examples of rare earth elements doped into the ceramic particles 100. In the ceramic particles 100 of this embodiment, the total amount of alkaline earth metal doping and rare earth element doping is 5 mol% or more and 30 mol% or less. The elements contained in ceramic particles 100 and their molar concentrations will be identified and measured using inductively coupled plasma mass spectrometry (ICP-MS).

[0027] The ceramic structure 1 of this embodiment has a plurality of pores 11. The plurality of pores 11 of the ceramic structure 1 can be classified into three types of pores 111, 112, and 113 depending on the difference in the pore formation process.

[0028] Figure 3 is the first diagram illustrating the features of the pores 11 in the ceramic structure 1 of this embodiment. Figure 3 shows the relationship between the pore diameters (horizontal axis) of the multiple pores 11 contained in the ceramic structure 1, as measured by a mercury porosimeter, and the log differential pore volume (vertical axis) at each pore diameter. As shown in Figure 3, when the pore diameters of the multiple pores 11 contained in the ceramic structure 1 are plotted on the horizontal axis and the log differential pore volume at each pore diameter is plotted on the vertical axis, the ceramic structure 1 of this embodiment satisfies the following relationships (1) to (3). (1) The first peak is in the range of pore diameter between 100 μm and less than 1000 μm. (2) A second peak is present in the range of pore diameter between 10 μm and less than 100 μm. (3) A third peak is present in the range of pore diameter between 0.1 μm and less than 10 μm.

[0029] The first peak P1 in the range A1, where the pore diameter is between 100 μm and 1000 μm, as shown in Figure 3, corresponds to the peak of pore 111 shown in Figure 2. The pore diameter of pore 111 depends on the pore diameter of the urethane foam used in the manufacturing method of the ceramic structure 1 described later. In the ceramic structure 1 of this embodiment, the log differential pore volume of the first peak P1 is 0.05 ml / g or more.

[0030] The second peak P2 in Figure 3, in the range A2 where the pore diameter is 10 μm or more and less than 100 μm, corresponds to the peak of pore 112 shown in Figure 2. Pores 112 are formed by the burning of the urethane foam used in the manufacturing method of the ceramic structure 1. In the ceramic structure 1 of this embodiment, the log differential pore volume of the second peak P2 is 0.05 ml / g or more.

[0031] The third peak P3 in Figure 3, in the range A3 where the pore diameter is 0.1 μm or more and less than 10 μm, corresponds to the peak of pore 113 shown in Figure 2. Pores 113 are gaps formed between adjacent ceramic particles 100 that form the ceramic structure 1, as the particles grow larger through sintering, but the overall volume does not change significantly. In the ceramic structure 1 of this embodiment, the log differential pore volume of the third peak P3 is 0.1 ml / g or more.

[0032] The porosity of the ceramic structure 1 in this embodiment is 60% to 93%. In the ceramic structure 1 of this embodiment, the number of cells is 5 to 50 (5 to 50 cells / 25.4 mm). The number of cells is calculated by acquiring an image of the cross-section of the ceramic structure 1 embedded in resin, setting a line segment of unit length (25.4 mm) at an arbitrary position in the acquired image, and measuring the number of pores (cells) on this line segment.

[0033] The ceramic structure 1 of this embodiment has a bulk density of 0.5 g / cm³. 3 More than 2.8g / cm 3 The following applies: Bulk density is calculated by determining the volume by measuring the external dimensions of ceramic structure 1 and by measuring the weight of ceramic structure 1.

[0034] Figure 4 is a second diagram illustrating the characteristics of the pores 11 of the ceramic structure 1 of this embodiment. Figure 4 shows the relationship between the pore diameter (horizontal axis) and the cumulative pore volume (vertical axis) of the multiple pores 11 contained in the ceramic structure 1, as measured by a mercury porosimeter. In the ceramic structure 1 of this embodiment, the cumulative pore volume V3 of the pores 113 with a pore diameter of 0.1 μm or more and less than 10 μm is 35% or more and 65% or less of the cumulative pore volume of the multiple pores 11. Specifically, as shown in Figure 4, the cumulative pore volume V3 of pore 113 is 0.079 ml / g, which corresponds to 41% of the cumulative pore volume of the multiple pores 11 (V1 + V2 + V3 = 0.192 ml / g). On the other hand, the cumulative pore volume V2 of pore 112 is 0.048 ml / g, which corresponds to 25% of the cumulative pore volume of the multiple pores 11 (0.192 ml / g), and the cumulative pore volume V1 of pore 111 is 0.065 ml / g, which corresponds to 34% of the cumulative pore volume of the multiple pores 11 (0.192 ml / g). Therefore, in the ceramic structure 1 of this embodiment, among the three types of pores 111, 112, and 113, the cumulative pore volume V3 of pore 113 with a pore diameter of 0.1 μm or more and less than 10 μm is the largest, followed by the cumulative pore volume V1 of pore 111 with a pore diameter of 100 μm or more and less than 1000 μm, and the cumulative pore volume V2 of pore 112 with a pore diameter of 10 μm or more and less than 100 μm is the smallest. This indicates that ceramic structure 1 has a relatively large specific surface area. Therefore, when ceramic structure 1 is used as a catalyst support, it can support a relatively large amount of catalyst.

[0035] Figure 5 is a diagram illustrating the schematic configuration of a reactor equipped with the catalyst complex of this embodiment. In this embodiment, the ceramic structure 1 becomes a catalyst complex 1a by supporting a catalyst made of metal. Examples of catalysts supported on the ceramic structure 1 include nickel (Ni), platinum (Pt), palladium (Pd), and ruthenium (Ru). The catalyst complex 1a of this embodiment is used as a catalyst in a methanation reaction that produces methane gas from carbon dioxide and hydrogen. In the methanation reactor 5 shown in Figure 5, the catalyst complex 1a is set inside the methanation reactor 5 and an electric field is applied to it by power supplied from an external power source 6. This makes it possible for the catalyst complex 1a to carry out the methanation reaction at a relatively low temperature.

[0036] In this embodiment, the catalyst composite 1a has a three-dimensional network structure in the ceramic structure 1 on which the metal is supported, resulting in superior gas flow compared to catalysts in which the metal is supported on a monolithic molded body. Furthermore, the ceramic particles 100 forming the ceramic structure 1 of the catalyst composite 1a contain cerium oxide as the main component, which enhances ionic conductivity and contributes to improved catalyst performance. In this embodiment, since the catalyst composite 1a is formed from ceramic particles 100 with relatively high ionic conductivity to form a single molded body, the stability of the current when an electric field is applied is improved and the interfacial resistance is reduced compared to when the catalyst is in particle form. In addition, because there are a relatively large number of pores 113 with a pore size of 0.1 μm or more and less than 10 μm, the specific surface area is relatively large, which can improve the performance of the supported catalyst. Therefore, the ceramic structure 1 is suitable for use as a catalyst support for electric field application in methanation reactions. Furthermore, the technical field to which the ceramic structure catalyst support for electric field application of this embodiment is applicable is not limited to methanation reactions, but can be applied to technical fields including reaction processes using catalysts that utilize electric fields formed by the supply of electricity.

[0037] Figure 6 is a flowchart illustrating the manufacturing method of the ceramic structure 1 according to this embodiment. Next, the manufacturing method of the ceramic structure 1 according to this embodiment will be described.

[0038] In the method for manufacturing the ceramic structure 1 of this embodiment, first, an inorganic binder is added to ceria (CeO2) powder to prepare a slurry (step S11). In step S11, the molar amounts of alkaline earth metals and rare earth elements doped into the ceramic particles 100 that form the ceramic structure 1 are adjusted. The alkaline earth metals and rare earth elements doped into the ceramic particles 100 can be added to the slurry as ceria powder, an inorganic binder, or an additive. The inorganic binder only needs to have enough heat resistance to maintain its function as a binder at the firing temperature in the firing process described later. A glass-based binder can be used as the inorganic binder. Using a glass-based binder allows firing at a lower temperature. However, when a glass-based binder is used, the heat resistance temperature of the resulting ceramic structure 1 tends to decrease. Therefore, when the ceramic structure 1 is to be used in a relatively high temperature range, it is desirable to use a metal oxide-based inorganic binder.

[0039] In the manufacturing method of the ceramic structure 1 of this embodiment, after step S11, the prepared slurry is used to coat the urethane foam (step S12). The urethane foam used in step S12 is a porous body having a mesh structure with three-dimensionally interconnected pores, and is burned off during the firing of the slurry for ceramic foam. For example, polyurethane foam can be used as the urethane foam. The number of cells in the three-dimensional mesh structure of the ceramic structure 1 can be adjusted by the number of cells in the urethane foam to be coated with the slurry.

[0040] In the manufacturing method of the ceramic structure 1 of this embodiment, the ceramic structure 1 is manufactured by firing the slurry coated on the urethane foam and burning off the urethane foam (step S13). The firing in step S13 is carried out at a temperature of about 1600°C to manufacture the ceramic structure 1 with a three-dimensional network structure.

[0041] In the manufacturing method of the ceramic structure 1 of this embodiment, when the slurry coated on the urethane foam is fired in step S13, a plurality of pores 111, 112, and 113 are formed in the ceramic structure 1. Pores 111, which have a pore diameter in the range of 100 μm or more and less than 1000 μm, are formed corresponding to the pores of the urethane foam. Pores 112, which have a pore diameter in the range of 10 μm or more and less than 100 μm, are formed corresponding to the areas where the urethane foam was present as the urethane foam burns away. Pores 113, which have a pore diameter in the range of 0.1 μm or more and less than 10 μm, are formed between ceramic particles due to necking when the ceramic particles forming the ceramic structure 1 grow grain by sintering, and are therefore smaller than both pores 111 and 112. In this way, the ceramic structure 1 of this embodiment has a plurality of pores 111, 112, and 113 having pore diameters classified into three types depending on the difference in the pore formation process.

[0042] In the method for producing the catalyst composite 1a of this embodiment, for example, the catalyst metal is supported on the ceramic structure 1 by an impregnation method. Specifically, the ceramic structure 1 is immersed in a solution containing the catalyst metal, and then dried to disperse and fix the metal on the surface of the ceramic structure 1.

[0043] The characteristics of the method for producing catalyst composite 1a in this embodiment will be explained, focusing on the differences from the method for producing the ceramic structure of the comparative example. In the comparative example, the relationship between the pore diameter of multiple pores contained in the ceramic structure and the log differential pore volume at each pore diameter, as measured by a mercury porosimeter, does not show a peak in the range of pore diameters between 10 μm and 100 μm. In other words, there are few pores with a pore diameter between 10 μm and 100 μm. When there are few pores with a pore diameter between 10 μm and 100 μm, the solution containing the metal catalyst does not penetrate deep into the ceramic structure, making it difficult for the catalyst to spread throughout the entire ceramic structure. As a result, the metal is mainly supported on the surface of the ceramic structure, and the metal is not supported deep inside the ceramic structure. Therefore, when the catalyst composite participates in a gaseous chemical reaction, although the gas penetrates deep into the interior of the ceramic structure, the chemical reaction does not proceed because the metal is not supported.

[0044] On the other hand, in the method for producing the catalyst complex 1a of this embodiment, when the ceramic structure 1 is immersed in a solution containing a catalyst metal, the metal-containing solution spreads throughout the ceramic structure 1 through pores 112 with a pore diameter of 10 μm or more and less than 100 μm. As a result, by drying the ceramic structure 1, which has been thoroughly coated with the metal-containing solution, the catalyst can be supported throughout the ceramic structure 1. When the ceramic structure 1, with the metal supported throughout, is used as a catalyst complex 1a to produce methane gas from carbon dioxide and hydrogen, as shown in Figure 5, the carbon dioxide and hydrogen supplied to the methanation reactor 5 mainly flow through pores 111 with a relatively large pore diameter, resulting in relatively small pressure loss. When the carbon dioxide and hydrogen spread throughout the catalyst complex 1a through the pores 111, they come into contact with the catalyst supported throughout the ceramic structure 1, and the methanation reaction proceeds throughout the catalyst complex 1a. Since the ceramic structure 1 has many pores 113 with relatively small pore diameters, the contact area between carbon dioxide and hydrogen and the catalyst is relatively large. Therefore, the amount of methane gas produced by the progress of the methanation reaction increases, which can improve the catalytic performance of the catalyst complex 1a.

[0045] Next, we will describe the evaluation tests conducted on the manufacturing method of the ceramic structure 1 of this embodiment. In these evaluation tests, we evaluated the effect of temperature changes during firing on the pore distribution.

[0046] Figure 7 illustrates the results of an evaluation test on the manufacturing method of a ceramic structure. In this evaluation test, samples 1 to 3 were prepared using the manufacturing method of the ceramic structure 1 of this embodiment described above, but with different firing temperatures. Sample 1 is a ceramic structure fired at 1200°C, sample 2 is a ceramic structure fired at 1400°C, and sample 3 is a ceramic structure fired at 1600°C. For these samples 1 to 3, the relationship between the pore diameter and the log differential pore volume at each pore diameter was measured using a mercury porosimeter. As shown in Figure 7, in the range of pore diameters from 100 μm to less than 1000 μm, it was confirmed that the log differential pore volume was smaller when fired at 1200°C and 1400°C compared to when fired at 1600°C. Furthermore, in the range of pore diameters from 0.1 μm to less than 10 μm, it was confirmed that the peak pore diameter decreased as the firing temperature decreased. On the other hand, it was confirmed that the peak pore size hardly changed in the range of pore diameters between 10 μm and 100 μm.

[0047] Figure 8 is the first diagram illustrating the samples used in the evaluation test. Figure 9 is the second diagram illustrating the samples used in the evaluation test. Figures 8 and 9 show cross-sectional images of the samples used in this evaluation test. Figure 8 is a cross-sectional image of sample 2, which was fired at a firing temperature of 1400°C, and Figure 9 is a cross-sectional image of sample 3, which was fired at a firing temperature of 1600°C. Figures 8 and 9 are cross-sectional images focusing on pores p11 with a pore diameter of less than 100 μm. In the cross-sectional image of sample 2 shown in Figure 8, pores p112 with a pore diameter in the range of 10 μm or more and less than 100 μm, and pores p113 with a pore diameter in the range of 0.1 μm or more and less than 10 μm can be seen. In the cross-sectional image of sample 3 shown in Figure 9, pores p113 with a pore diameter in the range of 0.1 μm or more and less than 10 μm can be seen. Comparing the pore size p113 in Figure 8 (Sample 2) and Figure 9 (Sample 3), it was confirmed that the pore size p113 in Sample 3 is larger than that of Sample 2, as explained in Figure 7.

[0048] As described above, the ceramic structure 1 of this embodiment has peaks P1, P2, and P3 of a certain size in each of the following ranges of pore diameters: A1, A2, A1, A2, and A3. This improves the gas flow in the pores 111 and 112 with a diameter of 10 μm or more and less than 100 μm, while also increasing the specific surface area by including pores 113 with a diameter of 0.1 μm or more and less than 10 μm. Therefore, it is possible to achieve both improved gas flow and an increased specific surface area.

[0049] Furthermore, according to the ceramic structure 1 of this embodiment, the log differential pore volume of the first peak P1 is 0.05 ml / g or more. In other words, the ceramic structure 1 has a certain volume of pores 111 with a pore diameter of 100 μm or more and less than 1000 μm, which improves the flowability of gases.

[0050] Furthermore, according to the ceramic structure 1 of this embodiment, the log differential pore volume of the second peak P2 is 0.05 ml / g or more. That is, the ceramic structure 1 has a certain volume of pores 112 with a pore diameter of 10 μm or more and less than 100 μm. As a result, when the ceramic structure 1 is immersed in a solution containing a catalytic metal, the metal-containing solution spreads throughout the entire ceramic structure 1 through the pores 112 with a pore diameter of 10 μm or more and less than 100 μm. This allows the catalyst to be supported throughout the entire ceramic structure 1.

[0051] Furthermore, according to the ceramic structure 1 of this embodiment, the log differential pore volume of the third peak P3 is 0.1 ml / g or more. That is, the ceramic structure 1 has a certain volume of pores 113 with a pore diameter of 0.1 μm or more and less than 10 μm, so the specific surface area of ​​the ceramic structure 1 can be increased.

[0052] Furthermore, according to the ceramic structure 1 of this embodiment, the ceramic structure 1 has a three-dimensional network structure in which a plurality of ceramic particles 100 are bonded to each other in various directions. Therefore, since the plurality of pores 11 are formed to face in various directions, the gas flowability can be improved.

[0053] Furthermore, according to the ceramic structure 1 of this embodiment, the ceramic structure 1 contains cerium oxide as its main component. This improves the ionic conductivity of the ceramic structure 1.

[0054] Furthermore, according to the ceramic structure 1 of this embodiment, the porosity of the ceramic structure 1 is between 60% and 93%. As a result, the ceramic structure 1 can suppress pressure loss while simultaneously improving gas flowability and increasing the specific surface area.

[0055] Furthermore, according to the ceramic structure 1 of this embodiment, the cumulative pore volume V3 of the pores 113 with a pore diameter of 0.1 μm or more and less than 10 μm among the plurality of pores 11 is 35% or more and 65% or less of the cumulative pore volume (V1 + V2 + V3) of the plurality of pores 11. As a result, the ceramic structure 1 has pores 113 with relatively small pore diameters. This makes it possible to further increase the specific surface area of ​​the ceramic structure 1.

[0056] Furthermore, according to the catalyst composite 1a of this embodiment, the number of cells in the ceramic structure 1 is between 5 and 50 per 25.4 mm, and it has a structure that facilitates gas flow. As a result, the ceramic structure 1 can suppress pressure loss while simultaneously improving gas flowability and increasing the specific surface area.

[0057] Furthermore, according to the catalyst composite 1a of this embodiment, the bulk density of the ceramic structure 1 is 0.5 g / cm³. 3 More than 2.8g / cm 3The structure is as follows, and has a structure that facilitates gas flow. As a result, the ceramic structure 1 can suppress pressure loss while simultaneously improving gas flowability and increasing the specific surface area.

[0058] Furthermore, according to the catalyst complex 1a of this embodiment, the catalyst complex 1a has a catalyst made of metal supported on a ceramic structure 1 which has a relatively large specific surface area. As a result, the catalyst complex 1a contains a relatively large amount of catalyst, which can improve the performance of the catalyst.

[0059] Furthermore, the ceramic structure 1, which serves as the catalyst support for electric field application in this embodiment, has a large specific surface area, allowing it to support a large amount of catalyst. Therefore, it is easier to bring out the performance of the supported catalyst.

[0060] <Second Embodiment> Figure 10 is a first enlarged view of the ceramic structure of the second embodiment. Figure 11 is a second enlarged view of the ceramic structure of the second embodiment. The ceramic structure 2 of the second embodiment differs in its configuration from the ceramic structure of the first embodiment (Figure 1).

[0061] The ceramic structure 2 of this embodiment is a porous body having a three-dimensional network structure, formed from ceramics. The ceramic structure 2 of this embodiment comprises a ceramic foam 10 and a covering portion 20.

[0062] The ceramic foam 10 has pores and is formed from a plurality of first ceramic particles. The ceramic foam 10 corresponds to the skeleton of the ceramic structure 2. The ceramic foam 10 has a plurality of pores 12, as shown in Figure 10, which is an image of a portion of the cross-section of the ceramic structure 2 taken at 25x magnification using a scanning electron microscope (SEM), and Figure 12, which is an enlarged view of part A in Figure 10 and is an image of a portion of the cross-section of the ceramic structure 2 taken at 300x magnification. As a result, the ceramic foam 10 has better gas flowability than a porous body having a structure in which a mesh-like skeleton of several micrometers is connected, a so-called monolithic molded body, and can reduce pressure loss when gas is flowed through it.

[0063] The first ceramic particles forming the ceramic foam 10 mainly contain cerium oxide (CeO2). Here, "the first ceramic particles mainly contain cerium oxide" means that the molar concentration of cerium oxide in the first ceramic particles is 50 mol% or more. The first ceramic particles in this embodiment are doped with alkaline earth metals and rare earth elements. Calcium is an example of an alkaline earth metal doped into the first ceramic particles. Gadolinium (Gd), lanthanum (La), yttrium (Y), and the like are examples of rare earth elements doped into the first ceramic particles. In the first ceramic particles of this embodiment, the total amount of alkaline earth metal doping and rare earth element doping is between 5 mol% and 30 mol%. The elements contained in the first ceramic particles and their molar concentrations are identified and measured using inductively coupled plasma mass spectrometry (ICP-MS).

[0064] The coating portion 20 is formed of a plurality of second ceramic particles and coats the ceramic foam 10. The average particle size of the second ceramic particles forming the coating portion 20 is smaller than the average particle size of the plurality of first ceramic particles forming the ceramic foam 10. The average particle size of the plurality of first ceramic particles forming the ceramic foam 10 and the average particle size of the second ceramic particles forming the coating portion 20 are measured by observing the cross-section formed by cutting a ceramic structure 2 (hereinafter referred to as "resin-embedded ceramic structure 2") impregnated with a two-component curing resin or the like. Specifically, the cross-section of the resin-embedded ceramic structure 2 is polished, and the average particle size of the ceramic particles is calculated using the intercept method on the image of the cross-section captured using a scanning electron microscope or the like. If the grain boundary phase is difficult to observe even after cross-sectional polishing of the cross-section, the cross-section may be treated by chemical etching or the like.

[0065] The second ceramic particles forming the coating portion 20 mainly contain cerium oxide. Here, "the second ceramic particles mainly contain cerium oxide" means that the molar concentration of cerium oxide in the second ceramic particles is 50 mol% or more. The second ceramic particles in this embodiment are doped with alkaline earth metals and rare earth elements. Calcium is an example of an alkaline earth metal doped into the second ceramic particles. Gadolinium (Gd), lanthanum (La), yttrium (Y), and the like are examples of rare earth elements doped into the second ceramic particles. In the second ceramic particles of this embodiment, the total amount of alkaline earth metal doping and rare earth element doping is between 5 mol% and 30 mol%. The identification of elements contained in the second ceramic particles and the measurement of their molar concentrations are performed using inductively coupled plasma mass spectrometry (ICP-MS), similar to the first ceramic particles.

[0066] In the ceramic structure 2 of this embodiment, the average of the porosity of the ceramic foam 10 and the porosity of the coating portion 20 is 60% to 93%. The porosity of the ceramic foam 10 is 5% to 65%. In the ceramic foam 10 of the ceramic structure 2 of this embodiment, the number of cells is 5 to 50 (5 to 50 cells / 25.4 mm). The number of cells is calculated by acquiring an image of the cross-section of the ceramic structure 2 in which the resin is embedded, setting a line segment of unit length (25.4 mm) at an arbitrary position in the acquired image, and measuring the number of pores (cells) on this line segment.

[0067] In the ceramic structure 2 of this embodiment, the ratio of the thickness of the ceramic foam 10 to the thickness of the coating portion 20 in a cross-section passing through the ceramic foam 10 and the coating portion 20 is 0.5 or more and 4 or less. Here, the method for calculating the ratio of the thickness of the ceramic foam 10 to the thickness of the coating portion 20 will be specifically explained. First, in an image including the ceramic foam 10 and two coating portions 20a and 20b arranged so as to sandwich the ceramic foam 10, as shown in Figure 11, boundaries BLa and BLb between the ceramic foam 10 and the coating portions 20a and 20b are set.

[0068] In setting the boundaries BLa and BLb in this embodiment, first, a cross-section of the resin-embedded ceramic structure 2 is polished to create a boundary setting sample. Next, a backscattered electron image is captured of the polished surface of the boundary setting sample using a scanning electron microscope (SEM). In the backscattered electron image obtained by the SEM, the degree of unevenness on the polished surface appears as contrast in the image, making it easy to see the differences in unevenness due to differences in the particle size of the ceramic particles. Next, image processing is performed on the backscattered electron image of the polished surface to determine the portion corresponding to the ceramic foam 10 and the portions corresponding to the coatings 20a and 20b on the polished surface. In this embodiment, the image processing software ImageJ is used to perform binarization on the backscattered electron image obtained by the SEM.

[0069] Figure 12 is the first figure showing the results of image processing on a boundary setting sample. Figure 13 is the second figure showing the results of image processing on a boundary setting sample. Figures 12 and 13 show the results of image processing applied to the cross-section included in the image shown in Figure 11. In Figure 12, which shows the results of image processing focusing on the ceramic foam 10, the portion 10p corresponding to the first ceramic particles forming the ceramic foam 10 is displayed relatively black, and the portion 20p corresponding to the coating portion 20 is relatively lighter than portion 10p. In Figure 13, which shows the results of image processing focusing on the coating portion 20, the portion 20p corresponding to the coating portion 20 is displayed relatively black, and the portion 10p corresponding to the first ceramic particles forming the ceramic foam 10 is whitish compared to portion 10p. In this embodiment, the results of image processing on boundary setting samples as shown in Figures 12 and 13 are used to determine the portion of the polished surface corresponding to the ceramic foam 10 and the portions corresponding to the coatings 20a and 20b, and the boundaries BLa and BLb between the ceramic foam 10 and the coatings 20a and 20b are set. In setting the boundaries BLa and BLb, either the results of image processing focusing on the ceramic foam 10 (Figure 12) or the results of image processing focusing on the coatings 20 (Figure 13) may be used.

[0070] After setting the boundaries BLa and BLb between the ceramic foam 10 and the covering portions 20a and 20b, a virtual line VL1 is set that passes through the ceramic foam 10 and the two covering portions 20a and 20b. The intersection point CP1 is defined as the intersection of virtual line VL1 and boundary BLa, the intersection point CP2 is defined as the intersection of virtual line VL1 and boundary BLb, and the intersection points CP3 and CP4 are defined as the intersection points CP3 and CP4 are defined as the intersection points CP1 and CP2 and CP3 and CP4, respectively, of the outer surfaces 201a and 201b of the two covering portions 20a and 20b. For each of the intersection points CP1, CP2, CP3, and CP4 on virtual line VL1, the distance between intersection point CP1 and intersection point CP2 is the thickness d10 of the ceramic foam 10, the distance between intersection point CP1 and intersection point CP3 is the thickness d20a of the covering portion 20a, and the distance between intersection point CP2 and intersection point CP4 is the thickness d20b of the covering portion 20b. The ceramic structure 1 of this embodiment satisfies the following equation (1). 0.5≦d10 / (d20a+d20b)≦4 (1)

[0071] Figure 14 is a third enlarged view of the ceramic structure 2 of this embodiment. Figure 14 is an enlarged view of part B of Figure 11, and is an image of a part of the cross-section of the ceramic structure 2 taken at a magnification of 1000 times.

[0072] In the ceramic structure 2 of this embodiment, the coating portion 20 has multiple coating layers stacked on top of each other. As shown in Figure 14, the coating portion 20 of this embodiment has three coating layers 21, 22, and 23 stacked on top of each other. For convenience, Figure 14 shows a dashed line BL12 indicating the boundary between coating layer 21 and coating layer 22, and a dashed line BL23 indicating the boundary between coating layer 22 and coating layer 23.

[0073] In the ceramic structure 2 of this embodiment, the coating portion 20 has cracks C20. As shown in Figure 14, multiple cracks C20 are formed in the coating portion 20. Specifically, within a 100 μm length range of the boundary BLc between the ceramic foam 10 and the coating portion 20, one to twenty cracks C20 are formed in the coating portion 20 (the length of the solid line L100 shown in Figure 14 corresponds to the 100 μm length of the boundary BLc). In the image shown in Figure 14, at least four cracks C20 can be seen within a 100 μm length range of the boundary BLc. The cracks C20 are formed along a direction substantially perpendicular to the boundary BLc. Of the four visible cracks C20, crack C20a is formed continuously from the surface 201 of the coating portion 20 to the boundary BLc. In the ceramic structure 2 of this embodiment, each of the four cracks C20 has a length (length in the direction from the surface 201 of the coating portion 20 toward the boundary BLc) of 10 μm or more. In the ceramic structure 1 of this embodiment, each of the four cracks C20 has a width (length in the direction along the boundary BLc) of 2 μm or more and 20 μm or less.

[0074] As shown in Figure 11, the ceramic structure 2 of this embodiment has a plurality of pores 12. The plurality of pores 12 in the ceramic structure 2 can be classified into four types of pores 121, 122, 123, and 124 based on the differences in the formation process of the pores 12.

[0075] Figure 15 is the first diagram illustrating the features of the pores 12 in the ceramic structure 2 of this embodiment. Figure 15 shows the relationship between the pore diameters (horizontal axis) of the multiple pores 12 contained in the ceramic structure 2 and the log differential pore volume (vertical axis) at each pore diameter, as measured by a mercury porosimeter, indicated by the solid line L2. As shown in Figure 15, the ceramic structure 2 of this embodiment satisfies the following relationships (1) to (4) when the pore diameters of the multiple pores 12 contained in the ceramic structure 2 are plotted on the horizontal axis and the log differential pore volume at each pore diameter is plotted on the vertical axis. Note that Figure 15 also shows the relationship between the pore diameters of the multiple pores 11 contained in the ceramic structure 1 of the first embodiment and the log differential pore volume at each pore diameter, indicated by the dashed line L1. (1) The first peak is in the range of pore diameter between 100 μm and less than 1000 μm. (2) A second peak is present in the range of pore diameter between 10 μm and less than 100 μm. (3) A third peak is present in the range of pore diameter between 0.1 μm and less than 10 μm. (4) A fourth peak is present in the range of pore diameter between 0.01 μm and less than 0.1 μm.

[0076] The first peak P1 in the range A1, where the pore diameter is between 100 μm and less than 1000 μm, as shown in Figure 15, corresponds to the peak of pore 121 shown in Figures 10 and 11. The pore diameter of pore 121 depends on the pore diameter of the urethane foam used in the manufacturing method of the ceramic structure 2 described later. In the ceramic structure 2 of this embodiment, the log differential pore volume of the first peak P1 is 0.05 ml / g or more.

[0077] The second peak P2 in Figure 15, in the range A2 where the pore diameter is 10 μm or more and less than 100 μm, corresponds to the peak of pore 122 shown in Figure 11. Pores 122 are formed by the burning of the urethane foam used in the manufacturing method of the ceramic structure 2. In the ceramic structure 2 of this embodiment, the log differential pore volume of the second peak P2 is 0.05 ml / g or more.

[0078] The third peak P3 in the range A3, where the pore diameter is between 0.1 μm and less than 10 μm, as shown in Figure 15, corresponds to the pore 123 shown in Figure 11. The pore 123 is a gap formed between adjacent first ceramic particles because the first ceramic particles forming the ceramic foam 10 grow larger through sintering, but the overall volume does not change significantly. In the ceramic structure 2 of this embodiment, the log differential pore volume of the third peak P3 is 0.1 ml / g or more.

[0079] The fourth peak P4 in Figure 15, in the range A4 where the pore diameter is 0.01 μm or more and less than 0.1 μm, corresponds to the peak of pore 124 shown in Figure 11. Pores 124 are gaps formed between adjacent second ceramic particles because the second ceramic particles forming the coating portion 20 grow larger through sintering, but the overall volume does not change significantly. In the ceramic structure 2 of this embodiment, the log differential pore volume of the fourth peak P4 is 0.1 ml / g or more.

[0080] Figure 16 is a second diagram illustrating the characteristics of the pores 12 in the ceramic structure 2 of this embodiment. Figure 16 shows the relationship between the pore diameter (horizontal axis) and the cumulative pore volume (vertical axis) of the multiple pores 12 contained in the ceramic structure 2, as measured by a mercury porosimeter. In the ceramic structure 2 of this embodiment, the cumulative pore volume V3 of the pores 123 with a pore diameter of 0.1 μm or more and less than 10 μm is 35% or more and 65% or less of the cumulative pore volume of the multiple pores 12. Specifically, as shown in Figure 16, the cumulative pore volume V3 of the pores 123 is 0.071 ml / g, which corresponds to 44% of the cumulative pore volume of the multiple pores 12 (V1 + V2 + V3 + V4 = 0.160 ml / g). On the other hand, the cumulative pore volume V2 of pore 122 is 0.024 ml / g, which corresponds to 15% of the cumulative pore volume of the multiple pores 12 (0.160 ml / g), and the cumulative pore volume V1 of pore 121 is 0.017 ml / g, which corresponds to 11% of the cumulative pore volume of the multiple pores 12 (0.160 ml / g). Furthermore, the cumulative pore volume V4 of pore 124 is 0.048 ml / g, which corresponds to 30% of the cumulative pore volume of the multiple pores 12 (0.160 ml / g).

[0081] The ceramic structure 2 of this embodiment, like the ceramic structure 1 of the first embodiment, becomes a catalyst composite by supporting a catalyst made of metal. Examples of catalysts supported on the ceramic structure 2 include nickel (Ni), platinum (Pt), palladium (Pd), and ruthenium (Ru). The catalyst composite of this embodiment is used as a catalyst in the methanation reaction that produces methane gas from carbon dioxide and hydrogen. The catalyst composite having the ceramic structure 2 is set in a methanation reactor and an electric field is applied by power supplied from an external power source. This makes it possible for the catalyst composite having the ceramic structure 2 to carry out the methanation reaction at a relatively low temperature.

[0082] Figure 17 is a flowchart illustrating the manufacturing method of the ceramic structure 2 according to this embodiment. Next, the manufacturing method of the ceramic structure 2 according to this embodiment will be described.

[0083] In the manufacturing method of the ceramic structure 2 of this embodiment, first, an inorganic binder is added to ceria (CeO2) powder to prepare a slurry for ceramic foam (step S21). In step S21, the molar amounts of alkaline earth metal and rare earth element doped into the first ceramic particles that form the ceramic foam 10 are adjusted. The alkaline earth metal and rare earth element doped into the first ceramic particles can be added to the slurry as ceria powder, an inorganic binder, or an additive. The inorganic binder only needs to have enough heat resistance to maintain its function as a binder at the firing temperature in the firing process described later. A glass-based binder can be used as the inorganic binder. Using a glass-based binder allows firing at a lower temperature. However, when a glass-based binder is used, the heat resistance temperature of the resulting ceramic structure 1 tends to decrease. Therefore, when the ceramic structure 2 is to be used in a relatively high temperature range, it is desirable to use a metal oxide-based inorganic binder.

[0084] In the manufacturing method of the ceramic structure 2 of this embodiment, following step S21, a resin foam is coated using the prepared ceramic foam slurry (step S22). The resin foam used in step S22 is a porous body having a mesh structure with three-dimensionally interconnected pores, and is formed from resin material that is burned off during the firing of the ceramic foam slurry. For example, polyurethane foam can be used as the resin foam. The number of cells in the three-dimensional mesh structure of the ceramic foam 10 can be adjusted by the number of cells in the resin foam to be coated with the slurry.

[0085] In the manufacturing method of the ceramic structure 2 of this embodiment, the slurry coated on the resin foam is then fired to burn off the resin foam, thereby producing a ceramic foam 10 (step S23). The firing in step S23 is carried out at a temperature of about 1600°C, which produces a ceramic foam 10 with a three-dimensional network structure formed by first ceramic particles with relatively large particle sizes.

[0086] In the manufacturing method of the ceramic structure 2 of this embodiment, ceria powder and a solvent, such as ethanol, are mixed to prepare a slurry for the coating portion (step S24). In step S24, the molar amounts of alkaline earth metal and rare earth element to be doped into the second ceramic particles that form the coating portion 20 are adjusted. The alkaline earth metal and rare earth element to be doped into the second ceramic particles can be added to the slurry as ceria powder, an inorganic binder, or an additive. The preparation of the slurry for the coating portion may be done at the same time as the preparation of the slurry for the ceramic foam.

[0087] In the manufacturing method of the ceramic structure 2 of this embodiment, the ceramic foam 10 prepared in step S23 is then coated with a coating slurry and dried (step S25). In step S25, the coating of the ceramic foam 10 with the coating slurry is performed using, for example, a dip method. This allows fine ceria powder to be coated onto the relatively dense ceramic foam 10. The thickness of the coating portion 20 in the ceramic structure 1 can be changed by the concentration of the coating slurry prepared in step S24 and the number of times the coating slurry is applied in step S25.

[0088] In the manufacturing method of the ceramic structure 2 of this embodiment, the ceramic foam 10 coated with the coating slurry produced in step S25 is then fired (step S26). The firing in step S26 is carried out at a relatively low temperature, causing the ceria powder contained in the coating slurry to form necking. This produces the ceramic structure 2.

[0089] In this embodiment, the catalyst composite having the ceramic structure 2 has a metal supported on it using the ceramic structure 2, for example, by an impregnation method. Specifically, the ceramic structure 2 is immersed in a solution containing the catalyst metal, and then dried to disperse and fix the metal on the surface of the coating portion 20 of the ceramic structure 2.

[0090] As described above, the ceramic structure 2 of this embodiment has peaks P1, P2, and P3 of a certain size in each of the following ranges of pore diameters: A1, A2, A1, A2, and A3. This improves the gas flow in the pores 121 and 122 with a diameter of 10 μm or more and less than 100 μm, while also increasing the specific surface area by including pores 123 with a diameter of 0.1 μm or more and less than 10 μm. Therefore, it is possible to achieve both improved gas flow and an increased specific surface area.

[0091] Furthermore, according to the ceramic structure 2 of this embodiment, the ceramic structure 2 includes a covering portion 20 that covers the ceramic foam 10. As a result, the specific surface area of ​​the ceramic structure 2 is the sum of the specific surface area of ​​the ceramic foam 10 and the specific surface area of ​​the covering portion 20, and is therefore larger than the specific surface area of ​​the ceramic foam 10 alone. Thus, while the ceramic foam 10 has a certain level of strength or more, the specific surface area can be increased and the gas flowability can be further improved.

[0092] Furthermore, according to the ceramic structure 2 of this embodiment, when the pore diameters of the multiple pores 12 contained in the ceramic structure 2, as measured by a mercury porosimeter, are plotted on the horizontal axis and the log differential pore volume at each pore diameter is plotted on the vertical axis, the following relationship (4) is satisfied. (4) A fourth peak is present in the range of pore diameter between 0.01 μm and less than 0.1 μm. As shown in equation (4), the ceramic structure 2 has a peak of a certain size in the pore diameter range of 0.01 μm to less than 0.1 μm. This makes it possible to further increase the specific surface area while simultaneously improving gas flowability and increasing the specific surface area.

[0093] Furthermore, according to the ceramic structure 2 of this embodiment, the log differential pore volume of the fourth peak is 0.1 ml / g or more. Thus, since the ceramic structure 2 has a certain volume of pores with a pore diameter of 0.01 μm or more and less than 0.1 μm, the specific surface area can be further increased.

[0094] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0095] [Example 1] In the above embodiment, the relationship between the pore diameters of multiple pores contained in the ceramic structure, measured by a mercury porosimeter, and the log differential pore volume at each pore diameter was such that the log differential pore volume at the first peak P1 and the log differential pore volume at the second peak P2 were 0.05 ml / g or greater, and the log differential pore volume at the third peak P3 was 0.1 ml / g or greater. The log differential pore volume at each peak is not limited to these values; it may be smaller.

[0096] [Differentiation 2] In the above-described embodiment, it was assumed that the ceramic structure contains cerium oxide as a main component. The main component of the ceramic structure 1 is not limited to this. By containing cerium oxide as a main component, the ion conductivity can be improved.

[0097] [Modified Example 3] In the above-described embodiment, it was assumed that the porosity of the ceramic structure is 60% or more and 93% or less. The range of the porosity of the ceramic structure is not limited to this. When the porosity is less than 60%, the fluidity of the gas decreases, and when the porosity is more than 93%, the strength of the ceramic structure decreases.

[0098] [Modified Example 4] In the above-described embodiment, it was assumed that the cumulative pore volume of pores having a pore diameter of 0.1 μm or more and less than 10 μm among the plurality of pores is 35% or more and 65% or less of the cumulative pore volume of the plurality of pores. The ratio of the cumulative pore volume of the pores to the cumulative pore volume of the plurality of pores is not limited to this. In the above-described embodiment, it was assumed that the cumulative pore volume of pores having a pore diameter of 0.1 μm or more and less than 10 μm is the largest among the plurality of types of pores, but the magnitude relationship of the cumulative pore volumes is not limited to this.

[0099] [Modified Example 5] In the above-described embodiment, it was assumed that the number of cells of the ceramic structure is 5 or more and 50 or less per 25.4 mm. The number of cells of the ceramic structure is not limited to this.

[0100] [Modified Example 6] In the first embodiment, the ceramic structure 1 has a bulk density of 0.5 g / cm 3 or more and 2.8 g / cm 3 or less. The bulk density of the ceramic structure is not limited to this value.

[0101] [Modified Example 7] In the second embodiment, the ceramic structure 2 comprises a ceramic foam 10 and a covering portion 30 that covers the ceramic foam 10. The configuration of the ceramic structure is not limited to this.

[0102] [Differentiation 8] In the second embodiment, the ceramic structure 2 is defined as having a fourth peak in the range of pore diameters between 0.01 μm and less than 0.1 μm, as measured by a mercury porosimeter, in the relationship between the pore diameters of the multiple pores contained in the ceramic structure and the log differential pore volume at each pore diameter, and the log differential pore volume of the fourth peak is defined as 0.1 ml / g or more. The presence or absence of a fourth peak in the range of pore diameters between 0.01 μm and less than 0.1 μm, as measured by a mercury porosimeter in the ceramic structure, and the log differential pore volume of the fourth peak are not limited to these definitions.

[0103] [Modification 9] In the above-described embodiment, the ceramic structure 1 is used as a catalyst support for electric field application in the catalyst composite 1a. The technical field to which the ceramic structure is applied is not limited thereto. It may also be applied to technical fields where a ceramic structure having a certain level of strength, a large specific surface area, and high gas flowability is applicable.

[0104] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate.

[0105] <Application Example 1> A ceramic structure, It has multiple pores, When the pore diameters of the multiple pores contained in the ceramic structure, as measured by a mercury porosimeter, are plotted on the horizontal axis and the log differential pore volume at each pore diameter is plotted on the vertical axis, the following relationships (1) to (3) are satisfied, characterized in that Ceramic structure. (1) The first peak is in the range of pore diameter between 100 μm and less than 1000 μm. (2) A second peak is present in the range of pore diameter between 10 μm and less than 100 μm. (3) A third peak is present in the range of pore diameter between 0.1 μm and less than 10 μm. <Application Example 2> A ceramic structure as described in Application Example 1, The log differential pore volume of the first peak is characterized by being 0.05 ml / g or greater. Ceramic structure. <Application Example 3> A ceramic structure as described in Application Example 1 or Application Example 2, The log differential pore volume of the second peak is characterized by being 0.05 ml / g or greater. Ceramic structure. <Application Example 4> A ceramic structure described in any one of the three application examples, The log differential pore volume of the third peak is characterized by being 0.1 ml / g or greater. Ceramic structure. <Application Example 5> A ceramic structure described in any one of Application Examples 1 to 4, Characterized by having a three-dimensional network structure, Ceramic structure. <Application Example 6> A ceramic structure described in any one of Application Examples 1 to 5, A product characterized by containing cerium oxide as its main component, Ceramic structure. <Application Example 7> A ceramic structure described in any one of the examples from Application Example 1 to Application Example 6, Characterized by having a porosity of 60% to 93%, Ceramic structure. <Application Example 8> A ceramic structure described in any one of Application Examples 1 to 7, The cumulative pore volume of the pores with a diameter of 0.1 μm or more and less than 10 μm among the plurality of pores is characterized in that it is 35% or more and 65% or less of the cumulative pore volume of the plurality of pores. Ceramic structure. <Application Example 9> A ceramic structure described in any one of Application Examples 1 to 8, It is characterized by having 5 to 50 cells per 25.4 mm. Ceramic structure. <Application Example 10> A ceramic structure described in any one of the examples from Application Example 1 to Application Example 9, Bulk density is 0.5 g / cm³ 3 More than 2.8g / cm 3 The following characteristics: Ceramic structure. <Application Example 11> The ceramic structure described in any one of the examples from Application Example 1 to Application Example 10 is further: Ceramic foam and, The invention is characterized by comprising a covering portion that covers the ceramic foam, Ceramic structure. <Application Example 12> A ceramic structure described in any one of Application Examples 1 to 11, The following relationship (4) is satisfied when the pore diameters of the multiple pores contained in the ceramic structure, as measured by a mercury porosimeter, are plotted on the horizontal axis and the log differential pore volume at each pore diameter is plotted on the vertical axis: Ceramic structure. (4) A fourth peak is present in the range of pore diameter between 0.01 μm and less than 0.1 μm. <Application Example 13> A ceramic structure as described in Application Example 12, The log differential pore volume of the fourth peak is characterized by being 0.1 ml / g or greater. Ceramic structure. <Application Example 14> A catalyst complex, A ceramic structure described in any one of Application Examples 1 to 13, The ceramic structure is supported by a catalyst made of metal, and comprises Catalyst complex. <Application Example 15> A catalyst support for electric field application, A ceramic structure comprising one of the examples described in Application Example 1 to Application Example 13, Catalyst support for electric field application. [Explanation of Symbols]

[0106] 1,2… Ceramic structures 1a... Catalyst complex 11,111,112,113,12,121,122,123,124… Pores A1, A2, A3, A4... range P1…First peak P2...Second peak P3…Third peak P4…The fourth peak V1, V2, V3, V4... Cumulative pore volume

Claims

1. A ceramic structure, It has multiple pores, When the pore diameters of the multiple pores contained in the ceramic structure, as measured by a mercury porosimeter, are plotted on the horizontal axis and the log differential pore volume at each pore diameter is plotted on the vertical axis, the following relationships (1) to (3) are satisfied, characterized in that Ceramic structure. (1) The first peak is located in the range of pore diameter between 100 μm and less than 1000 μm. (2) The second peak is present in the range of pore diameter between 10 μm and less than 100 μm. (3) A third peak is present in the range of pore diameter between 0.1 μm and less than 10 μm.

2. A ceramic structure according to claim 1, The log differential pore volume of the first peak is characterized by being 0.05 ml / g or more. Ceramic structure.

3. A ceramic structure according to claim 1 or claim 2, The log differential pore volume of the second peak is characterized by being 0.05 ml / g or more. Ceramic structure.

4. A ceramic structure according to claim 1 or claim 2, The log differential pore volume of the third peak is characterized by being 0.1 ml / g or more. Ceramic structure.

5. A ceramic structure according to claim 1 or claim 2, Characterized by having a three-dimensional network structure, Ceramic structure.

6. A ceramic structure according to claim 1 or claim 2, A product characterized by containing cerium oxide as its main component, Ceramic structure.

7. A ceramic structure according to claim 1 or claim 2, Characterized by having a porosity of 60% to 93%, Ceramic structure.

8. A ceramic structure according to claim 1 or claim 2, The cumulative pore volume of the pores with a diameter of 0.1 μm or more and less than 10 μm among the plurality of pores is characterized in that it is 35% or more and 65% or less of the cumulative pore volume of the plurality of pores. Ceramic structure.

9. A ceramic structure according to claim 1 or claim 2, The number of cells is characterized by being 5 to 50 per 25.4 mm. Ceramic structure.

10. A ceramic structure according to claim 1 or claim 2, Bulk density is 0.5 g / cm³ 3 2.8g / cm or more 3 The following characteristics: Ceramic structure.

11. The ceramic structure according to claim 1 or claim 2 further, Ceramic foam and, The invention is characterized by comprising a covering portion that covers the ceramic foam, Ceramic structure.

12. A ceramic structure according to claim 11, The following relationship (4) is satisfied when the pore diameters of the multiple pores contained in the ceramic structure, as measured by a mercury porosimeter, are plotted on the horizontal axis and the log differential pore volume at each pore diameter is plotted on the vertical axis: Ceramic structure. (4) A fourth peak is present in the range of pore diameter between 0.01 μm and less than 0.1 μm.

13. A ceramic structure according to claim 12, The log differential pore volume of the fourth peak is characterized by being 0.1 ml / g or more. Ceramic structure.

14. A catalyst complex, A ceramic structure according to claim 1 or claim 2, The ceramic structure is supported by a catalyst made of metal, and comprises Catalyst complex.

15. A catalyst support for electric field application, A ceramic structure comprising the ceramic structure according to claim 1 or claim 2, Catalyst support for electric field application.

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