Ceramic porous body

Abstract

To improve the catalytic capability and durability of a ceramic porous body and increase the strength.SOLUTION: A ceramic porous body has a three-dimensional network structure with interconnected pores formed, wherein the ceramic porous body includes a primary component composed of at least one of cerium oxide (CeO2) and zirconium oxide (ZrO2), and a first subcomponent that is a metal element with a variable valence number and that can form a rock salt-type structure oxide having a melting point of 1400°C or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a ceramic porous body. [Background technology]

[0002] Conventionally, various catalysts have been known as catalysts for promoting redox reactions such as hydrogen production reaction by water thermal decomposition. For example, Non-Patent Document 1 discloses cerium oxide (CeO 2 Patent Document 1 discloses a configuration in which a network-like porous ceramic structure made of cerium oxide (CeO2) is used to promote a reaction in which water and carbon dioxide are co-pyrolyzed to produce hydrogen and carbon monoxide. Patent Document 1 discloses a hydrogen production catalyst made of a composite oxide of cerium oxide and praseodymium oxide. Patent Document 2 discloses a nanocomposite material for hydrogen production in which a catalytic substance such as cerium oxide is supported on a porous support containing mullite. Patent Document 3 discloses a composite nanofiber catalyst containing a fiber-type support containing mullite or the like and a metal catalyst such as cerium oxide. Non-Patent Document 2 discloses a nanocomposite material for hydrogen production in which a catalytic substance such as cerium oxide is supported on a porous ... 2 ) is used as an oxidation-reduction catalyst, and Non-Patent Document 3 discloses a metal oxide in which zirconium oxide is added to cerium oxide as a metal oxide having an oxidation-reduction ability. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-14813 A [Patent Document 2] JP 2020-131188 A [Patent Document 3] JP 2020-163367 A [Non-patent literature]

[0004] [Non-Patent Document 1] Stefan Zoller et al., "A solar tower fuel plant for the thermochemical production of kerosene from H2O and CO2", Joule 6, 1606-1616, July 20, 2022. [Non-Patent Document 2] EI Kauppi et al., "ZrO2 Acting as a Redox Catalyst", Top Catal (2016) 59:823-832. [Non-Patent Document 3] Masato Machida, "Hydrogen generation using large-capacity oxygen storage materials", ENEOS Technical Review, Vol. 51, No. 3 (September 2009) Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, a configuration using cerium oxide, zirconium oxide, or the like as a catalyst for promoting an oxidation-reduction reaction such as a hydrogen generation reaction has been known, but further improvement in catalytic performance and durability of such metal oxide catalysts has been desired. For example, a technology for improving catalytic performance by further doping another metal to cerium oxide as in Patent Document 1 has been known, but a technology for further suppressing the decrease in durability due to performance deterioration accompanying repeated cycles of oxidation and reduction reactions has not been fully studied. In particular, when a mesh-like porous ceramic structure is adopted as described in Non-Patent Document 1, improvement in strength as well as improvement in catalytic performance and durability has been desired. Therefore, when an oxidation-reduction catalyst is constituted by a ceramic porous body having a three-dimensional mesh structure, a technology for improving catalytic performance and durability as well as increasing strength has been desired. [Means for solving the problem]

[0006] The present disclosure can be realized in the following forms. (1) According to one embodiment of the present disclosure, there is provided a ceramic porous body having a three-dimensional network structure in which interconnected pores are formed. The ceramic porous body is made of cerium oxide (CeO 2 ) and zirconium oxide (ZrO 2 ) and a first subcomponent which is a metal element whose ionic valence changes and which can become a rock-salt structure oxide having a melting point of 1400° C. or higher. According to the ceramic porous body of this embodiment, it is possible to improve the performance and durability as an oxidation-reduction catalyst, and also to increase the strength. (2) In the ceramic porous body of the above embodiment, nickel (Ni) may be contained as the first subcomponent. With this configuration, when the ceramic porous body is used as an oxidation-reduction catalyst, the catalytic activity can be improved as the ionic valence of nickel changes between trivalent and divalent. Furthermore, when nickel becomes divalent and precipitates as a rock-salt structure oxide, the melting point of the resulting nickel oxide (II) (NiO) is much higher than the temperature used as an oxidation-reduction catalyst. This prevents the precipitated nickel oxide (II) from melting and causing the first subcomponent to be lost, thereby further improving the durability of the ceramic porous body. (3) In the ceramic porous body of the above embodiment, the main component is cerium oxide (CeO 2 With such a configuration, in an oxidation-reduction catalyst containing cerium oxide as a main component, it is possible to improve the performance as an oxidation-reduction catalyst, as well as the durability and strength. (4) In the ceramic porous body of the above embodiment, the content of nickel (Ni) may be 1 to 30 mass % calculated as oxide. With such a configuration, it is possible to ensure the effect of improving the catalytic performance, durability, and strength by including nickel as the first minor component, and to suppress a decrease in the catalytic activity of the ceramic porous body caused by an excessive amount of the first minor component. (5) The ceramic porous body of the above embodiment may further contain at least one of titanium (Ti) and aluminum (Al) as a second subcomponent. With this configuration, the strength of the ceramic porous body 10 can be further increased. (6) In the ceramic porous body of the above embodiment, the content of the second subcomponent may be 1 to 20 mass % in terms of oxide. With such a configuration, the effect of improving the strength of the ceramic porous body by including the second subcomponent can be secured, and a decrease in the catalytic activity of the ceramic porous body caused by an excessive content of the second subcomponent can be suppressed. (7) In the ceramic porous body of the above embodiment, the number of cells in the three-dimensional network structure may be 5 to 50 cells / 25.4 mm. With this configuration, the ceramic porous body can be prevented from becoming weak and flow path resistance inside the ceramic porous body can be reduced. The present disclosure may be realized in various forms other than those described above, such as a method for manufacturing a ceramic porous body, a hydrogen production apparatus for hydrothermal decomposition utilizing an oxidation-reduction reaction of a ceramic porous body, and a carbon monoxide production apparatus by carbon dioxide thermal decomposition. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is an explanatory diagram showing the appearance of a ceramic porous body. [Diagram 2] 3 is a flowchart showing a method for producing a ceramic porous body. [Diagram 3] FIG. 2 is an explanatory diagram showing the composition and measurement results of each sample. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A. Composition of ceramic porous body: FIG. 1 is an explanatory diagram showing the appearance of a ceramic porous body 10 according to the present embodiment. The ceramic porous body 10 has a three-dimensional network structure in which interconnected pores are formed, and is made of cerium oxide (CeO 2 ) and zirconium oxide (ZrO2 ), and a first subcomponent that is a metal element whose ion valence changes and can become a rock-salt structure oxide having a melting point of 1400°C or more. In the present specification, the specific component is "the main component" means that the content of the specific component is 50 mass% or more. The ceramic porous body 10 of this embodiment can be used as an oxidation-reduction catalyst as described later, and the above-mentioned three-dimensional network structure is a shape that can reduce pressure loss when the ceramic porous body 10 is used. The content of cerium oxide and zirconium oxide in the ceramic porous body 10 and the content of other components can be measured by, for example, inductively coupled plasma mass spectrometry (ICP-MS).

[0009] As described above, the main component of the ceramic porous body 10 may be composed of cerium oxide alone, zirconium oxide alone, or a mixture of cerium oxide and zirconium oxide. Such a metal oxide constituting the main component of the ceramic porous body 10 is also called a "catalytic oxide." The main component of the ceramic porous body 10 desirably contains at least cerium oxide.

[0010] As described above, the first subcomponent of the ceramic porous body 10 is a metal element whose ionic valence changes and which can become a rock-salt structure oxide (oxide with a sodium chloride structure) having a melting point of 1400°C or higher. The term "metal element capable of becoming a rock-salt structure oxide" refers to a metal element whose ionic valence decreases to two in a reducing atmosphere when the ionic valence changes with a change in the atmosphere, and which can become a rock-salt structure oxide. Such a first subcomponent is usually dissolved in a catalytic oxide such as cerium oxide. When the ceramic porous body 10 is used as an oxidation-reduction catalyst and exposed to a reducing atmosphere, the first subcomponent becomes an oxide and precipitates on the surface of the catalytic oxide.

[0011] The first subcomponent, which can change its ion valence and become a rock-salt structure oxide having a melting point of 1400°C or more, can be, for example, at least one of manganese (Mn), cobalt (Co), and nickel (Ni). The first subcomponent desirably contains at least nickel. When the first subcomponent contains nickel, the content of nickel in the ceramic porous body 10 is desirably 1 to 30 mass% in terms of oxide. When the content of nickel is less than 1 mass% in terms of oxide, the effect of improving the catalytic performance, durability, and strength by including nickel as the first subcomponent may become insufficient. In addition, when the content of nickel exceeds 30 mass% in terms of oxide, the amount of the first subcomponent becomes excessive relative to the amount of the catalytic oxide, and therefore the catalytic activity of the ceramic porous body 10 may be suppressed, so that the above range is desirable.

[0012] The ceramic porous body 10 of the present embodiment may further contain at least one of titanium (Ti) and aluminum (Al) as a second subcomponent. By adding titanium (Ti) or aluminum (Al) as the second subcomponent, the strength of the ceramic porous body 10 can be increased.

[0013] When the ceramic porous body 10 contains the second subcomponent, the content of the second subcomponent in the ceramic porous body 10 is desirably 1 to 20 mass % in terms of oxide. If the content of the second subcomponent is less than 1 mass % in terms of oxide, the effect of improving the strength of the ceramic porous body 10 by including the second subcomponent may be insufficient. If the content of the second subcomponent exceeds 20 mass % in terms of oxide, the content of the second subcomponent, which hardly contributes to the catalytic activity, becomes excessive, and the catalytic activity of the ceramic porous body 10 may be suppressed, so that the above range is desirable.

[0014] In the ceramic porous body 10, the number of cells in the three-dimensional network structure is not particularly limited, but is preferably 5 to 50 cells / 25.4 mm. Here, the number of cells is the number of bubbles (cells) present on a line segment of unit length (25.4 mm) when the line segment is imagined on the cut surface of the ceramic porous body 10. If the number of cells in the ceramic porous body 10 is less than 5 cells / 25.4 mm, the individual bubbles formed in the ceramic porous body 10 become large and the strength becomes insufficient, which may make it difficult to maintain the shape of the ceramic porous body 10 and to manufacture the ceramic porous body 10. If the number of cells in the ceramic porous body 10 exceeds 50 cells / 25.4 mm, the individual bubbles formed in the ceramic porous body 10 become small, which increases the effect of increasing the flow resistance, so that it is preferable to set the number in the above range.

[0015] B. Manufacturing method of ceramic porous body: 2 is a flow chart showing a method for producing the ceramic porous body 10. To produce the ceramic porous body 10, first, a raw material powder containing a catalytic oxide and a first subcomponent is prepared (step T100). The first subcomponent may be added to the raw material powder as a metal powder as the first subcomponent, a powder of a metal oxide containing a metal as the first subcomponent, or a powder of a metal compound other than an oxide. Then, an inorganic binder is added to the raw material powder prepared in step T100 to prepare a slurry (step T110).

[0016] When preparing the ceramic porous body 10 containing the second subcomponent described above, in step T100, a raw material powder containing the second subcomponent in addition to the catalytic oxide and the first subcomponent may be prepared. Specifically, when adding the second subcomponent, a metal powder as the second subcomponent, a powder of a metal oxide containing a metal as the second subcomponent, or a powder of a metal compound other than an oxide may be added to the raw material powder. When preparing the ceramic porous body 10 containing the first subcomponent and the second subcomponent, at least a part of the first subcomponent and the second subcomponent to be added to the ceramic porous body 10 may be added to the raw material powder as an inorganic binder in step T110.

[0017] The inorganic binder used in step T110 only needs to have a heat resistance sufficient to maintain its function as a binder at the firing temperature in the firing step described below. A glass-based binder can also be used as the inorganic binder, and the use of 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 porous body 10 is likely to decrease, so when the ceramic porous body 10 is used in a relatively high temperature range, it is desirable to use a metal oxide-based inorganic binder.

[0018] Next, the resin foam is coated with the slurry prepared in step T110 (step T120). The resin foam used in step T120 is a porous body having a network structure with three-dimensionally connected pores, and is formed of a resin material that is burned away in the firing step. For example, polyurethane foam can be used as the resin foam. The number of cells in the three-dimensional network structure of the ceramic porous body 10 is determined by the number of cells of the resin foam to be coated with the slurry. Therefore, in step T120, it is desirable to use a resin foam having a three-dimensional network structure with a cell number of 5 to 50 cells / 25.4 mm, for example, and a resin foam having a desired number of cells may be appropriately selected according to the pore diameter of the ceramic porous body 10 to be manufactured. The bulk density of the ceramic porous body 10 and the skeleton thickness in the three-dimensional network structure of the ceramic porous body 10 can be adjusted by the amount of slurry coated on the resin foam in step T120 and the number of coatings.

[0019] Thereafter, the resin foam coated with the slurry is fired to burn off the resin foam (step T130), completing the ceramic porous body 10. The firing temperature in step T130 may be any temperature at which the catalyst oxide can be sintered, and may be, for example, a temperature of 1400° C. or higher. The firing time may be, for example, 1 to 5 hours.

[0020] According to the ceramic porous body 10 of the present embodiment configured as described above, the ceramic porous body 10 having a three-dimensional network structure is made of cerium oxide (CeO 2 ) and zirconium oxide (ZrO 2 ) and a first subcomponent which is a metal element whose ionic valence changes and which can become a rock-salt structure oxide having a melting point of 1400°C or higher. This makes it possible to improve the performance and durability as an oxidation-reduction catalyst and to increase the strength.

[0021] Specifically, it is believed that when the ceramic porous body 10 contains the first subcomponent, the first subcomponent gives and receives electrons as the ionic valence of the first subcomponent changes when the ceramic porous body 10 is used as an oxidation-reduction catalyst, and this electron transfer promotes the oxidation-reduction reaction, thereby improving the catalytic activity. Furthermore, the ceramic porous body 10 contains the first subcomponent, which can increase the strength of the ceramic porous body 10.

[0022] In addition, when the ceramic porous body 10 is used as an oxidation-reduction catalyst as described above and exposed to a reducing atmosphere, the first subcomponent dissolved in the catalyst oxide is reduced and the ionic valence is reduced to 2, and the rock-salt structure oxide is precipitated on the surface of the catalyst oxide. In general, the temperature at which the oxidation-reduction catalyst is used is less than 1400°C, so that if the melting point of the rock-salt structure oxide containing the first subcomponent is 1400°C or higher, the rock-salt structure oxide precipitated on the catalyst oxide remains on the catalyst oxide and is not lost. Therefore, when the ceramic porous body 10 is subsequently exposed to an oxidizing atmosphere, the first subcomponent precipitated on the catalyst oxide as a rock-salt structure oxide is oxidized and dissolved in the catalyst oxide again, and the state before the rock-salt structure oxide was precipitated can be restored. Therefore, even if the ceramic porous body 10 is used as an oxidation-reduction catalyst and is repeatedly exposed to a reducing atmosphere and an oxidizing atmosphere, it is possible to suppress deterioration of the ceramic porous body 10 and increase the durability of the ceramic porous body 10. Nickel (Ni) is particularly desirable because it is highly effective in improving the durability of the ceramic porous body 10, since the melting point of the rock-salt structure oxide (NiO) generated when the ionic valence changes from trivalent to divalent is 1955° C., which is sufficiently high relative to the operating temperature.

[0023] On the other hand, even if a metal element whose ion valence changes and whose catalytic activity can be increased by adding it to the catalyst oxide is added to the catalyst oxide as an auxiliary component, if the melting point of the reduced rock-salt structure oxide is less than 1400°C, the temperature of use as an oxidation-reduction catalyst may exceed the melting point. When the temperature of use exceeds the melting point, the precipitated rock-salt structure oxide melts and flows. As a result, when exposed to an oxidizing atmosphere thereafter, the auxiliary component cannot be dissolved again in the catalyst oxide, and the auxiliary component is lost from the ceramic porous body, and the ceramic porous body cannot recover the catalytic activity before the rock-salt structure oxide was precipitated, and the catalytic activity decreases. In the ceramic porous body 10 of this embodiment, the rock-salt structure oxide of the first auxiliary component precipitated during use as an oxidation-reduction catalyst does not melt, so that the deterioration of the ceramic porous body 10 can be suppressed.

[0024] C. Usage of ceramic porous bodies: As described above, the ceramic porous body 10 of the present embodiment can be used as an oxidation-reduction catalyst. Specifically, for example, it can be used as an oxidation-reduction catalyst in a hydrogen production device for hydrothermal decomposition that utilizes the oxidation-reduction reaction of the ceramic porous body, or in a carbon monoxide production device by carbon dioxide thermal decomposition. EXAMPLES

[0025] <Preparation of a sample with a three-dimensional network structure> FIG. 3 is an explanatory diagram showing the compositions of samples S1 to S10 and the measurement results for each sample. As described below, ceramic porous body samples S1 to S10 having a three-dimensional network structure and various compositions were produced according to the production method shown in FIG. 2, and the catalytic activity and durability were compared. For the ceramic porous bodies of samples S1 to S10, polyurethane foams having similar porosity and average pore size were used as the resin foam in step T120. Samples S8 to S10 are comparative samples because they do not contain a first minor component that is a metal element whose ion valence changes and that can become a rock-salt structure oxide with a melting point of 1400° C. or more.

[0026] [Sample S1] In step T100, cerium oxide (CeO 2) was used to prepare a raw material powder. Nickel (Ni) was used as the first subcomponent, and nickel oxide (NiO) was added to prepare the raw material powder, thereby adding the first subcomponent. At this time, the first subcomponent was added to the raw material powder so that the amount of the first subcomponent in the ceramic porous body 10 was the ratio (1 mass%) shown in FIG. 3 in terms of oxide. In step T110, a ceria-based binder was used as the inorganic binder. Then, in order to facilitate coating of the resin foam in step T120, water was appropriately added to the slurry to adjust the viscosity of the slurry. After coating the resin foam with the slurry, it was dried at 60 to 100°C and fired at 1500°C for 1 to 5 hours (step T130), and the ceramic porous body of sample S1 was obtained.

[0027] [Samples S2-S4] The ceramic porous bodies 10 of samples S2 to S4 were produced in the same manner as sample S1, except that the amount of the first subcomponent in the raw material powder prepared in step T100 (proportion in terms of oxide in the ceramic porous body 10) was different from that of sample S1, as shown in Figure 3.

[0028] [Sample S5] In sample S5, the main component was cerium oxide (CeO 2 ) was used as the first minor component, and nickel (Ni) was used as the first minor component. In step T100, nickel oxide was added to the raw material powder so that the amount of the first minor component in the ceramic porous body 10 (proportion in terms of oxide in the ceramic porous body 10) was 15 mass %, the same as in sample S2. Sample S5 also contained titanium (Ti) as the second minor component, and in step T100, titanium oxide (TiO 2 ) was further added to prepare the raw material powder. The other manufacturing conditions were the same as those for sample S1.

[0029] [Sample S6] In sample S6, the main component was cerium oxide (CeO 2In step T100, titanium oxide (TiO 2 ) was added to the ceramic porous body 10 so that the amount of the second subcomponent (the proportion in terms of oxide in the ceramic porous body 10) was 12 mass % for Ti. 2 ) was added to the raw material powder. In step T110, an alumina-based binder was used as the inorganic binder, and the alumina-based binder was added so that the amount of the second minor component in the ceramic porous body 10 was 8 mass % Al, to prepare a slurry. The other manufacturing conditions were the same as those of sample S5.

[0030] [Sample S7] In sample S7, the main component was cerium oxide (CeO 2 ) was used as the second subcomponent, and aluminum (Al) was used as the second subcomponent. In step T110, an alumina-based binder was used as the inorganic binder, and the alumina-based binder was added so that the aluminum content in the ceramic porous body 10 was 10 mass % in terms of oxide, to prepare a slurry. The other manufacturing conditions were the same as those of sample S5.

[0031] [Sample S8] The raw material powder prepared in step T100 is mixed with cerium oxide (CeO 2 ) was used, and the first and second subcomponents were not added.

[0032] [Sample S9] In sample S9, the main component is cerium oxide (CeO 2 ) was used, and aluminum (Al) was used as the second subcomponent without adding the first subcomponent. That is, in step T100, cerium oxide (CeO 2 ) was used to prepare a raw material powder. In step T110, an alumina-based binder was used as the inorganic binder, and the alumina-based binder was added so that the aluminum content in the ceramic porous body 10 was 10 mass % in terms of oxide, to prepare a slurry. The other manufacturing conditions were the same as those for sample S1.

[0033] [Sample S10] Sample S10 contains cerium oxide (CeO 2 ) was used, iron (Fe) was used as the first subcomponent, and aluminum (Al) was used as the second subcomponent. However, Fe used as the first subcomponent in sample S10 has a melting point of 1371°C as iron oxide (FeO), which is a rock salt structure oxide, and does not satisfy the condition of "1400°C or higher". When producing sample S10, in step T100, iron oxide was added to the raw material powder so that the content of the first subcomponent in terms of oxide in the ceramic porous body was the ratio shown in Figure 3 (20 mass%). In addition, in step T110, an alumina-based binder was used as the inorganic binder, and the alumina-based binder was added to prepare a slurry so that the content of aluminum in terms of oxide in the ceramic porous body was 3.8 mass%. Other manufacturing conditions were the same as those of sample S1.

[0034] <Content of the first and second subcomponents> The contents of the first and second minor components in each sample were measured as oxide-equivalent values ​​by inductively coupled plasma mass spectrometry (ICP-MS). In Figure 3, these are shown as "amount of the first minor component [mass%]" and "amount of the second minor component [mass%]".

[0035] <Cell count measurement> The number of cells for each sample was determined by setting a line segment of unit length (25.4 mm) at an arbitrary position on the cross-sectional image of each sample after embedding it in resin and counting the number of air bubbles (cells) on this line segment.

[0036] <Amount of hydrogen produced> For each sample, the reduction reaction was carried out by supplying nitrogen at a temperature of 1400°C, and H with a mole fraction of 0.03 was supplied at a temperature of 1200°C. 2The oxidation reaction was allowed to proceed by supplying nitrogen containing O. The amount of hydrogen generated during the oxidation reaction was then measured using a gas chromatograph. Figure 3 shows the amount of hydrogen generated during the oxidation reaction when such a cycle of reduction and oxidation reactions was first performed.

[0037] <Number of cycles until catalyst deterioration> The reduction and oxidation reactions were repeated as described above, and the amount of hydrogen generated during the oxidation reaction was measured for each cycle of reduction and oxidation reactions. In Figure 3, the number of cycles at which the amount of hydrogen generated decreased by 33% or more (deteriorated to 2 / 3 or less of the initial characteristic) compared to the amount of hydrogen measured in the first cycle is shown as the "number of cycles until catalyst degradation."

[0038] <Compressive strength measurement> For each sample, a rectangular sample with a side length of 30 mm and a thickness of 10 mm was prepared, and the strength when compressed from both the top and bottom was measured using an autograph. Specifically, the compressive strength was calculated by identifying the stress at the time of destruction when compressed at a stroke speed of 0.5 mm / min. The compressive strength was measured using the sample before the above-mentioned reduction and oxidation reaction cycle was performed.

[0039] <Evaluation Results> As shown in FIG. 3, it was confirmed that the addition of the first subcomponent, which is a metal element that changes ion valence and can become a rock-salt structure oxide with a melting point of 1400°C or more, improves the catalytic performance as well as the durability and strength. For example, even when Fe is added as the first subcomponent, the amount of hydrogen generated during the oxidation reaction increases compared to when the first subcomponent is not added, and it is possible to improve the catalytic performance (comparison between sample S10 and samples S8 and S9). However, it was confirmed that when Fe, whose melting point when it becomes a rock-salt structure oxide is lower than 1400°C, is used as the first subcomponent, the number of cycles until catalyst deterioration is fewer, deterioration is faster, and durability is inferior compared to when a first subcomponent whose melting point when it becomes a rock-salt structure oxide is 1400°C or more is used (comparison between samples S1 to S7 and sample S10). It was also confirmed that the strength (compressive strength) of the ceramic porous body having a three-dimensional network structure is increased by adding the first subcomponent that can become a rock-salt structure oxide with a melting point of 1400°C or more as described above (comparison between samples S1 to S4 and sample S8). It was also confirmed that the content of the first minor component, which can become a rock-salt structure oxide having a melting point of 1400°C or higher, is desirably 30 mass% or less from the viewpoint of catalytic activity (amount of hydrogen produced) (comparison between Samples S1 to S3 and Sample S4). Furthermore, it was confirmed that the strength of the ceramic porous body 10 can be further increased by adding a second minor component, which is at least one of titanium (Ti) and aluminum (Al) (comparison between Samples S1 to S4 and Samples S5 to S7).

[0040] The present disclosure is not limited to the above-mentioned embodiments, etc., and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features in the embodiments corresponding to the technical features in each form described in the Summary of the Invention column can be appropriately replaced or combined in order to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0041] The present disclosure can also be realized in the following forms. [Application example 1] A ceramic porous body having a three-dimensional network structure in which interconnected pores are formed, Cerium oxide (CeO 2 ) and zirconium oxide (ZrO 2 ) A main component composed of at least one of A first minor component is a metal element whose ionic valence changes and can become a rock-salt structure oxide having a melting point of 1400°C or higher; Characterized in that it comprises Porous ceramic body. [Application example 2] The ceramic porous body according to Application Example 1, The first subcomponent is nickel (Ni). Porous ceramic body. [Application example 3] The ceramic porous body according to Application Example 1 or 2, The main component is cerium oxide (CeO 2 ) Porous ceramic body. [Application example 4] The ceramic porous body according to Application Example 2, The nickel (Ni) content is 1 to 30 mass% in terms of oxide. Porous ceramic body. [Application example 5] The ceramic porous body according to any one of Application Examples 1 to 4, further comprising: The second subcomponent is at least one of titanium (Ti) and aluminum (Al). Porous ceramic body. [Application Example 6] The ceramic porous body according to Application Example 5, The content of the second subcomponent is 1 to 20 mass% in terms of oxide. Porous ceramic body. [Application Example 7] The ceramic porous body according to any one of Application Examples 1 to 6, The number of cells in the three-dimensional mesh structure is 5 to 50 cells / 25.4 mm. Porous ceramic body. [Explanation of symbols]

[0042] 10...Porous ceramic body

Claims

1. A ceramic porous body having a three-dimensional network structure in which communicating pores are formed, Cerium oxide (CeO ２ ) and zirconium oxide (ZrO ２ ) A main component composed of at least one of the following: A first subcomponent is a metal element whose ionic valence changes and which can become a rock-salt structure oxide having a melting point of 1400° C. or higher; Characterized in that it comprises Porous ceramic body.

2. The ceramic porous body according to claim 1, The first subcomponent is nickel (Ni). Porous ceramic body.

3. The ceramic porous body according to claim 2, The main component is cerium oxide (CeO ２ ) Porous ceramic body.

4. The ceramic porous body according to claim 2, The nickel (Ni) content is 1 to 30 mass% in terms of oxide. Porous ceramic body.

5. The ceramic porous body according to claim 1, further comprising: The second subcomponent is at least one of titanium (Ti) and aluminum (Al). Porous ceramic body.

6. The ceramic porous body according to claim 5, The content of the second subcomponent is 1 to 20 mass% in terms of oxide. Porous ceramic body.

7. The ceramic porous body according to any one of claims 1 to 6, The number of cells in the three-dimensional mesh structure is 5 to 50 cells / 25.4 mm. Porous ceramic body.

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