Zirconia-based porous material, and method for producing a zirconia-based porous material

Abstract

To provide a zirconia-based porous material in which the change in pore size distribution due to crushing treatment is small and the decrease in specific surface area due to heating is suppressed. [Solution] A zirconia-based porous body containing 40% by mass or more of zirconia and 5% by mass or more of rare earth element oxides up to 60% by mass, satisfying all of the following conditions (1) and (2) in the pore size distribution based on the mercury intrusion method: (1) The maximum value of the peak in the range of 10 nm to less than 300 nm is 1.0 ml / g or more and 4.0 ml / g or less. (2) The pore volume in the range of 300 nm to 100,000 nm is 0.05 ml / g or more and 1.00 ml / g or less.

Description

Technical Field

[0001] The present invention relates to a zirconia-based porous body and a method for producing the zirconia-based porous body.

Background Art

[0002] In a zirconia-based porous body serving as a catalyst carrier for exhaust gas purification, in order to maintain a highly dispersed state of a noble metal catalyst even after being exposed to high temperature for a long time, control of pore diameter has been studied.

[0003] In Patent Document 1, in the pore size distribution based on the BJH method, having a peak at a pore diameter of 20 to 100 nm, when the half-width of the peak obtained from the measured pore size distribution curve is W and the height of the peak is P, the P / W ratio is 0.05 or more, and the total pore volume is 0.5 cm 3 / g or more, and (2) after heat treatment at 1000 °C for 12 hours, having a peak at a pore diameter of 20 to 100 nm, the P / W ratio is 0.03 or more, and having a specific surface area of at least 40 m 2 / g, and a zirconia-based porous body having a total pore volume of 0.3 cm 3 / g or more is disclosed (see particularly Claim 1).

[0004] In Patent Document 2, in the pore size distribution based on the BJH method, having peaks at pore diameters of 8 to 20 nm and 30 to 100 nm, and a zirconia-based porous body having a total pore volume of 0.4 cc / g or more, and in the pore size distribution based on the BJH method, having a peak at a pore diameter of 20 to 110 nm, and a zirconia-based porous body having a total pore volume of 0.4 cc / g or more are disclosed (see particularly Claim 1).

[0005] In Patent Document 3, a zirconia-based porous body having a total pore volume of at least 0.75 ml / g after heat treatment at 1000 °C for 3 hours, and a pore volume of pores having a diameter of 10 to 100 nm after heat treatment at 1000 °C for 3 hours being at least 30% of the total pore volume is disclosed (see particularly Claim 1).

[0006] Patent Document 4 states that in the pore distribution based on the BJH method, all of the following conditions (1) to (3) are met in the range of 2 nm to 200 nm, and the pore volume in the range of 100 nm to 1000 nm in the pore distribution based on the mercury intrusion method is 0.01 cm³. 3 / g or more 0.25cm 3 A porous zirconia-based composite oxide characterized by having a density of less than or equal to / g. (1) The dV / dlogD peak is in the range of 2 nm to 100 nm. (2) The maximum value of the dV / dlogD peak is between 1.5 and 5.0. (3) The pore volume in the range of 2 nm to 100 nm is 0.30 cm³. 3 / g or more 1.50cm 3 A zirconia-based porous material with a weight of less than / g is disclosed. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2015-189655 [Patent Document 2] Japanese Patent Publication No. 2006-036576 [Patent Document 3] Japanese Patent Publication No. 2008-081392 [Patent Document 4] Japanese Patent Publication No. 2023-178603 [Overview of the project] [Problems that the invention aims to solve]

[0008] Patent documents 1-4 attempt to suppress the decrease in specific surface area after exposure to high temperatures by controlling the pore structure of zirconia-based porous materials.

[0009] Here, the zirconia-based porous material is slurryed, its particle size adjusted by wet grinding, and then coated onto a honeycomb structure for use. Alternatively, the zirconia-based porous material may be stirred for an extended period after slurrying and before coating.

[0010] However, wet grinding and prolonged stirring during catalyst preparation disrupt the particle aggregation state and alter the pore structure, leading to problems such as a decrease in specific surface area when exposed to high temperatures and a reduction in catalyst performance.

[0011] The present invention has been made in view of the above-mentioned problems, and its objective is to provide a zirconia-based porous body in which the change in pore size distribution due to crushing treatment is small and the decrease in specific surface area due to heating is suppressed. Furthermore, it is also objective to provide a method for producing the zirconia-based porous body. [Means for solving the problem]

[0012] The present invention provides the following: [1] 40% by mass or more of zirconia, Oxides of rare earth elements in a concentration of 5% to 60% by mass and Includes, A zirconia-based porous material characterized by satisfying all of the following conditions (1) to (2) in its pore size distribution based on the mercury intrusion method. (1) The maximum peak value in the range of 10 nm to less than 300 nm is between 1.0 ml / g and 4.0 ml / g. (2) The pore volume between 300 nm and 100,000 nm is between 0.05 ml / g and 1.00 ml / g.

[0013] According to the above configuration, in the pore size distribution based on the mercury intrusion method, the maximum value of the peak in the range of 10 nm to less than 300 nm is between 1.0 ml / g and 4.0 ml / g, thus suppressing the decrease in specific surface area when exposed to high temperatures (especially 1100°C).

[0014] Zirconia-based porous materials loosen starting from pores and cavities, resulting in changes in pore size distribution and a decrease in specific surface area. The inventors have found that the presence or absence of pores with a diameter of 300 nm or more does not significantly reduce the specific surface area upon heating. They then reduced the pore volume in the region of the pore diameter distribution above 300 nm. Specifically, the pore volume between 300 nm and 100,000 nm was set to 1.00 ml / g or less. Because the material does not have pores concentrated in the region above 300 nm, it is hard and the pore distribution is less likely to change due to crushing. Since there is little change in the pore distribution before and after crushing, the reduction in specific surface area when exposed to high temperatures can be suppressed even after crushing.

[0015] Furthermore, Patent Documents 1-4 do not disclose that the pore volume in the range of 300 nm to 100,000 nm is 1.00 ml / g or less. In addition, the manufacturing method described in Patent Documents 1-4 cannot achieve a pore volume of 1.00 ml / g or less in the range of 300 nm to 100,000 nm.

[0016] Furthermore, according to the above configuration, since it contains oxides of rare earth elements in a range of 5% to 60% by mass, it is possible to suppress the decrease in specific surface area when exposed to high temperatures, both before and after the crushing treatment.

[0017] Based on the above, the configuration described in [1] provides a zirconia-based porous body in which the change in pore size distribution due to crushing treatment is small and the decrease in specific surface area due to heating is suppressed.

[0018] Furthermore, the present invention provides the following: [2] The zirconia-based porous material according to [1], characterized in that, in the pore size distribution based on the mercury intrusion method, the number of peaks in the range of 10 nm to less than 300 nm is one.

[0019] In the pore size distribution based on the mercury intrusion method described above, if there is only one peak in the range of 10 nm to less than 300 nm, the zirconia-based porous material becomes harder and its pore distribution becomes less susceptible to change due to crushing treatment.

[0020] Furthermore, the present invention provides the following: [3] When the pore volume in the range of 10 nm to 200 nm in the pore distribution based on the BJH method after crushing treatment under the crushing treatment conditions described below is defined as pore volume A, and the pore volume in the range of 10 nm to 200 nm in the pore distribution based on the BJH method before the crushing treatment is defined as pore volume B, The pore volume A is 0.2 ml / g or more and 1.2 ml / g or less. The zirconia-based porous material according to [1] or [2], characterized in that the pore volume retention rate X, represented by the following formula (4), is 0.80 or more and 1.10 or less. <Crushing process conditions> Place 30g of zirconia-based porous material and 300ml of pure water into a 500ml beaker and disperse using an ultrasonic homogenizer for 5 minutes. Then, dry at 110°C for 24 hours. <Pore volume maintenance rate X> [(Pore Volume A) / (Pore Volume B)] Equation (4)

[0021] If the retention rate of pore volume in the range of 10 nm to 200 nm before and after the crushing treatment (the retention rate of pore volume X) is between 0.80 and 1.10, it can be said that the pore volume has not changed significantly even after the crushing treatment. Also, if the pore volume A is 0.2 ml / g or more, it can be said that the pore volume after the crushing treatment is sufficiently large. As mentioned above, the pore volume in the range of 300 nm to 100,000 nm is 1.00 ml / g or less, and there are almost no pores in the range above 300 nm, so the pore volume in the range of 300 nm to 100,000 nm does not change.

[0022] Furthermore, the present invention provides the following: [4] When the specific surface area after the crushing treatment under the following crushing conditions, and after heat treatment at 1100°C for 3 hours under atmospheric pressure and air, is defined as specific surface area A, and the specific surface area before the crushing treatment, and after heat treatment at 1100°C for 3 hours under atmospheric pressure and air, is defined as specific surface area B, The aforementioned specific surface area A is 15m 2 / g or more 60m2 is below / g, The zirconia-based porous body according to any one of the above [1] to [3], characterized in that the maintenance rate Y of the specific surface area represented by the following formula (5) is 0.85 or more and 1.05 or less. <Crushing treatment conditions> Put 30 g of the zirconia-based porous body and 300 ml of pure water into a 500 ml beaker, and disperse for 5 minutes with an ultrasonic homogenizer. Then, dry at 110 °C for 24 hours. <Maintenance rate Y of specific surface area> [(Specific surface area A) / (Specific surface area B)] Formula (5)

[0023] When the maintenance rate Y of the specific surface area is 0.85 or more and 1.05 or less, it can be said that the specific surface area does not change significantly even when the crushing treatment is performed. Also, when the specific surface area A is 15 m 2 / g or more, it can be said that the specific surface area after the crushing treatment and after heat treatment at 1100 °C for 3 hours is sufficiently large.

[0024] Furthermore, the present invention provides the following. [5] The zirconia-based porous body according to any one of the above [1] to [4], characterized in that the specific surface area after heat treatment at 1000 °C for 3 hours under atmospheric pressure and in an air atmosphere is 20 m 2 / g or more and 80 m 2 / g or less.

[0025] When the specific surface area after heat treatment at 1000 °C for 3 hours under atmospheric pressure and in an air atmosphere is 20 m 2 / g or more and 80 m 2 / g or less, it can be said that the specific surface area after heat treatment at 1000 °C is sufficiently large.

[0026] Furthermore, the present invention provides the following. [6] The zirconia-based porous body according to any one of the above [1] to [5], characterized in that the specific surface area before heat treatment is 30 m 2 / g or more and 120 m 2 / g or less.

[0027] The specific surface area before heat treatment was 30 m². 2 / g or more 120m 2 If the specific surface area is less than or equal to / g, it can be said that the specific surface area before heat treatment is sufficiently large. A large specific surface area before heat treatment makes it easier to increase the specific surface area after heat treatment.

[0028] Furthermore, the present invention provides the following: [7] Step 1 involves simultaneously adding a zirconium salt solution and a sulfate chlorine agent to heated water to obtain a basic zirconium sulfate-containing slurry, Step 2 involves removing unreacted zirconium salts and soluble zirconium salts, Step 3 involves adding a rare earth salt solution to the basic zirconium sulfate-containing slurry obtained in step 2, and then adding an alkali to obtain a zirconium-containing hydroxide. Step 4 involves heat-treating the zirconium-containing hydroxide obtained in step 3 to obtain a zirconia-based porous body. A method for producing a zirconia-based porous body according to any one of the above [1] to [6], characterized by including the above.

[0029] According to the above configuration, in step 1, by simultaneously adding a zirconium salt solution and a sulfate chlorinator to heated water and uniformly chlorinating it, the pore size distribution of basic zirconium sulfate can be controlled to satisfy the above conditions (1) to (2). In other words, only specific pores that are important for suppressing the decrease in specific surface area due to heating can be formed. During the crushing process, the particles break down starting from voids, especially macropores of 300 nm or more, so the absence of unnecessary pores results in particles that are difficult to crush.

[0030] Furthermore, according to the above configuration, by removing unreacted zirconium salt and soluble zirconium salt in step 2, it is possible to prevent the generation of fine particles during neutralization and the generation of coarse particles due to the aggregation of secondary particles. As a result, a zirconia-based porous material can be obtained that is difficult to break down and has little change in pore size distribution after crushing treatment. [Effects of the Invention]

[0031] According to the present invention, it is possible to provide a zirconia-based porous material in which the change in pore size distribution due to crushing treatment is small and the decrease in specific surface area due to heating is suppressed. Furthermore, a method for producing the zirconia-based porous material can be provided. [Brief explanation of the drawing]

[0032] [Figure 1] This figure shows the pore distribution of the zirconia-based porous material of Example 1 based on the mercury intrusion method. [Figure 2] This figure shows the pore distribution of the zirconia-based porous material in Example 2 based on the mercury intrusion method. [Figure 3] This figure shows the pore distribution of the zirconia-based porous body based on the mercury intrusion method in Example 3. [Figure 4] This figure shows the pore distribution of the zirconia-based porous material of Comparative Example 1 based on the mercury intrusion method. [Figure 5] This figure shows the pore distribution of the zirconia-based porous material of Comparative Example 2 based on the mercury intrusion method. [Figure 6] This figure shows the pore distribution of the zirconia-based porous material of Comparative Example 3 based on the mercury intrusion method. [Figure 7] This figure shows the pore distribution of the zirconia-based porous material of Example 1 based on the BJH method. [Figure 8] This figure shows the pore distribution of the zirconia-based porous material of Example 2 based on the BJH method. [Figure 9] This figure shows the pore distribution of the zirconia-based porous material of Example 3 based on the BJH method. [Figure 10] This figure shows the pore distribution of the zirconia-based porous material of Example 4 based on the BJH method. [Figure 11] This figure shows the pore distribution of the zirconia-based porous material of Example 5 based on the BJH method. [Figure 12] This figure shows the pore distribution of the zirconia-based porous material of Example 6 based on the BJH method. [Figure 13] This figure shows the pore distribution of the zirconia-based porous material of Comparative Example 1 based on the BJH method. [Figure 14] This figure shows the pore distribution of the zirconia-based porous material of Comparative Example 3 based on the BJH method. [Modes for carrying out the invention]

[0033] Embodiments of the present invention will be described below. However, the present invention is not limited to these embodiments. In this specification, the zirconia-based porous material contains 10% by mass or less of an impurity metal compound, including hafnium. In this specification, the expressions "contains" and "includes" include the concepts of "contains," "includes," "substantially consists of," and "consists only of."

[0034] The maximum and minimum values ​​of the content of each component shown below are, independently of the content of other components, the preferred minimum and preferred maximum values ​​of the present invention. Furthermore, the maximum and minimum values ​​of the various parameters (measured values, etc.) shown below are, independently of the content (composition) of each component, the preferred minimum and maximum values ​​of the present invention.

[0035] [Zirconia-based porous material] The zirconia-based porous material according to this embodiment, as will be described in detail later, contains zirconia and an oxide of a rare earth element. The applications of the zirconia-based porous material according to this embodiment are not particularly limited, but it is useful as a catalyst support for exhaust gas purification. When used as a catalyst support for exhaust gas purification, examples of catalysts that can be supported include precious metal catalysts.

[0036] <Pore diameter distribution based on mercury intrusion method> The zirconia-based porous material according to this embodiment satisfies all of the following conditions (1) to (2) in terms of pore size distribution based on the mercury intrusion method. (1) The maximum peak value in the range of 10 nm to less than 300 nm is between 1.0 ml / g and 4.0 ml / g. (2) The pore volume between 300 nm and 100,000 nm is between 0.05 ml / g and 1.00 ml / g.

[0037] According to the zirconia-based porous material, the maximum value of the peak in the range of 10 nm to less than 300 nm in the pore size distribution based on the mercury intrusion method is between 1.0 ml / g and 4.0 ml / g, thus suppressing the decrease in specific surface area when exposed to high temperatures (especially 1100°C). The aforementioned peak refers to the peak of dV / dlogD.

[0038] In the pore size distribution based on the mercury intrusion method described above, the number of peaks in the range of 10 nm to less than 300 nm may be one or multiple (for example, two (bimodal)), but it is preferable that there is one. When the number of peaks is one, the zirconia-based porous material becomes harder and the pore distribution becomes less susceptible to change due to crushing treatment. "Maximum peak value in the range of 10nm to less than 300nm" refers to the value of the peak (dV / dlogD) if there is only one peak in the range of 10nm to less than 300nm. If there are multiple peaks in the range of 10nm to less than 300nm, "Maximum peak value in the range of 10nm to less than 300nm" refers to the peak with the largest maximum value (dV / dlogD) among the multiple peaks. Furthermore, if there are two or more peaks in the range of 10 nm to less than 300 nm that satisfy the maximum value of 1.0 ml / g or more and 4.0 ml / g or less, then if the maximum value of the peak with the largest value satisfies the condition of 1.0 ml / g or more and 4.0 ml / g or less, then the condition "the maximum value of the peaks in the range of 10 nm to less than 300 nm is 1.0 ml / g or more and 4.0 ml / g or less" is satisfied, regardless of whether the maximum values ​​of the other peaks satisfy this condition.

[0039] The maximum value of the aforementioned peak is preferably 1.2 ml / g or more, and more preferably 1.4 ml / g or more. The maximum value of the aforementioned peak is preferably 3.8 ml / g or less, and more preferably 3.6 ml / g or less. The maximum value of the aforementioned peak is preferably 1.2 ml / g or more and 3.8 ml / g or less, more preferably 1.4 ml / g or more and 3.6 ml / g or less.

[0040] Furthermore, in the zirconia-based porous material, the pore volume in the region between 300 nm and 100,000 nm is between 0.05 ml / g and 1.00 ml / g, according to the pore size distribution based on the mercury intrusion method. Because it does not have pores concentrated in the region with a pore diameter of 300 nm or more, it is hard and the pore distribution is less likely to change due to crushing treatment. Since there is little change in the pore distribution before and after crushing treatment, the decrease in specific surface area when exposed to high temperatures can be suppressed even after crushing treatment.

[0041] The pore volume between 300 nm and 100,000 nm is preferably 0.10 ml / g or more, and more preferably 0.15 ml / g or more. The pore volume between 300 nm and 100,000 nm is preferably 0.95 ml / g or less, and more preferably 0.90 ml / g or less. The pore volume between 300 nm and 100,000 nm is preferably 0.10 ml / g to 0.95 ml / g, and more preferably 0.15 ml / g to 0.90 ml / g.

[0042] In the zirconia-based porous material, the maximum value of the peak in the range of 300 nm to 100,000 nm in the pore size distribution based on the mercury intrusion method is preferably 3.0 ml / g or less, more preferably 2.0 ml / g or less, and even more preferably 1.0 ml / g or less. The maximum value of the aforementioned peak is preferably 0.1 ml / g or more and 3.0 ml / g or less, more preferably 0.2 ml / g or more and 2.0 ml / g or less, and even more preferably 0.3 ml / g or more and 1.0 ml / g or less.

[0043] Details of the method for measuring pore distribution based on the mercury intrusion method described above are as shown in the examples.

[0044] <Hardness> The zirconia-based porous body preferably has a hardness of 0.50 GPa or more and 1.00 GPa or less as measured by a method compliant with ISO 14577. When the hardness is 0.50 GPa or more, the pore structure becomes less likely to change by the crushing treatment.

[0045] The hardness is more preferably 0.52 GPa or more, and still more preferably 0.54 GPa or more. The hardness is preferably as high as possible. For example, it is 0.98 GPa or less, 0.96 GPa or less, etc. The hardness is more preferably 0.52 GPa or more and 0.98 GPa or less, and still more preferably 0.54 GPa or more and 0.96 GPa or less.

[0046] Details of the method for measuring the hardness are based on the method described in the examples.

[0047] <Pore size distribution based on the BJH method> For the zirconia-based porous body, when the pore volume in the range of 10 nm or more and 200 nm or less in the pore distribution based on the BJH method after the crushing treatment under the following crushing treatment conditions is defined as pore volume A, and the pore volume in the range of 10 nm or more and 200 nm or less in the pore distribution based on the BJH method before the crushing treatment is defined as pore volume B, the pore volume A is 0.20 ml / g or more and 1.20 ml / g or less, it is preferable that the maintenance rate X of the pore volume represented by the following formula (4) is 0.80 or more and 1.10 or less. <Crushing treatment conditions> Put 30 g of the zirconia-based porous body and 300 ml of pure water into a 500 ml beaker, and disperse for 5 minutes with an ultrasonic homogenizer. Then, dry at 110 °C for 24 hours. The dispersion by the ultrasonic homogenizer is performed at 550 W and an amplitude of 37%. More specifically, use "Sonifier SFX550" (Nippon Emason Co., Ltd.) as the ultrasonic homogenizer and disperse at 550 W and an amplitude of 37%. <Maintenance rate X of pore volume> [(Pore volume A) / (Pore volume B)] Formula (4)

[0048] If the retention rate of pore volume in the range of 10 nm to 200 nm before and after the crushing treatment (the retention rate of pore volume X) is between 0.80 and 1.10, it can be said that the pore volume has not changed significantly even after the crushing treatment. Furthermore, if the pore volume A is 0.2 ml / g or more, it can be said that the pore volume after the crushing treatment is sufficiently large.

[0049] The pore volume retention rate X is more preferably 0.82 or higher, and even more preferably 0.84 or higher. The pore volume retention rate X is preferable to be as large as possible, but for example, it should be 1.08 or less, 1.06 or less, etc. The pore volume retention rate X is more preferably 0.82 or more and 1.08 or less, and even more preferably 0.84 or more and 1.06 or less.

[0050] The pore volume A is more preferably 0.22 ml / g or more, and even more preferably 0.24 ml / g or more. The pore volume A is preferably as large as possible, but for example, it should be 1.18 ml / g or less, 1.16 ml / g or less, etc. The pore volume A is more preferably 0.22 ml / g or more and 1.18 ml / g or less, and even more preferably 0.24 ml / g or more and 1.16 ml / g or less.

[0051] The pore volume B is more preferably 0.22 ml / g or more, and even more preferably 0.24 ml / g or more. The pore volume B is preferably as large as possible, but for example, it can be 1.18 ml / g or less, 1.16 ml / g or less, etc. The pore volume B is more preferably 0.22 ml / g or more and 1.18 ml / g or less, and even more preferably 0.24 ml / g or more and 1.16 ml / g or less.

[0052] Details of the method for measuring pore distribution based on the BJH method described above are as shown in the examples.

[0053] <Retention rate of specific surface area after heat treatment at 1100°C for 3 hours, before and after crushing> When the zirconia-based porous material is subjected to the following crushing treatment conditions and then heat-treated at 1100°C for 3 hours under atmospheric pressure and in an air atmosphere, the specific surface area after the crushing treatment is defined as specific surface area A, and the specific surface area before the crushing treatment and heat-treated at 1100°C for 3 hours under atmospheric pressure and in an air atmosphere is defined as specific surface area B, The aforementioned specific surface area A is 15m 2 / g or more 60m 2 It is less than / g It is preferable that the maintenance ratio Y of the specific surface area, represented by the following formula (5), is 0.85 or more and 1.05 or less. <Crushing process conditions> 30 g of zirconia-based porous material and 300 ml of pure water are placed in a 500 ml beaker and dispersed using an ultrasonic homogenizer for 5 minutes. Then, it is dried at 110°C for 24 hours. The dispersion using the ultrasonic homogenizer is performed at 550 W and 37% amplitude. More specifically, a "Sonifier SFX550" (Emerson Japan Co., Ltd.) is used as the ultrasonic homogenizer, and the dispersion is performed at 550 W and 37% amplitude. <Maintenance ratio of specific surface area Y> [(Specific surface area A) / (specific surface area B)] Equation (5)

[0054] If the maintenance rate Y of the specific surface area is 0.85 or more and 1.05 or less, it can be said that the specific surface area has not changed significantly even after crushing. Also, if the specific surface area A is 15m² 2 If the value is 1 / g or higher, the specific surface area after crushing and heat treatment at 1100°C for 3 hours can be said to be sufficiently large.

[0055] The maintenance ratio Y of the specific surface area is more preferably 0.87 or higher, and even more preferably 0.89 or higher. The maintenance ratio Y of the specific surface area is preferable to be as large as possible, for example, 1.03 or less, 1.01 or less, etc. The maintenance ratio Y of the specific surface area is more preferably 0.87 or more and 1.03 or less, and even more preferably 0.89 or more and 1.01 or less.

[0056] The specific surface area A is more preferably 15 m². 2 / g or more, more preferably 16m2 It is 1 / g or more. The specific surface area A is preferable as it is larger, for example, 58 m². 2 / g or less, 56m 2 It is less than / g, etc. The specific surface area A is more preferably 15 m². 2 / g or more 58m 2 / g or less, more preferably 16m 2 / g or more 56m 2 It is less than / g.

[0057] The specific surface area B is more preferably 16 m². 2 / g or more, more preferably 17m 2 It is 1 / g or more. The specific surface area B is preferable as it is larger, for example, 58 m². 2 / g or less, 56m 2 It is less than / g, etc. The specific surface area B is more preferably 16 m². 2 / g or more 58m 2 / g or less, more preferably 17m 2 / g or more 56m 2 It is less than / g.

[0058] <Retention rate of specific surface area after heat treatment at 1000°C for 3 hours, before and after crushing> When the zirconia-based porous material is subjected to the following crushing treatment conditions and then heat-treated at 1000°C for 3 hours under atmospheric pressure and an air atmosphere, the specific surface area after the crushing treatment is defined as specific surface area A-2, and the specific surface area before the crushing treatment and heat-treated at 1000°C for 3 hours under atmospheric pressure and an air atmosphere is defined as specific surface area B-2, It is preferable that the maintenance ratio of the specific surface area Y-2, represented by the following formula (6), is 0.85 or more and 1.05 or less. <Crushing process conditions> 30 g of zirconia-based porous material and 300 ml of pure water are placed in a 500 ml beaker and dispersed using an ultrasonic homogenizer for 5 minutes. Then, it is dried at 110°C for 24 hours. The dispersion using the ultrasonic homogenizer is performed at 550 W and 37% amplitude. More specifically, a "Sonifier SFX550" (Emerson Japan Co., Ltd.) is used as the ultrasonic homogenizer, and the dispersion is performed at 550 W and 37% amplitude. <Maintenance ratio of specific surface area Y-2> [(Specific surface area A-2) / (Specific surface area B-2)] Formula (6)

[0059] If the retention rate of the specific surface area Y-2 is between 0.85 and 1.05, it can be said that the specific surface area has not changed significantly even after the crushing treatment.

[0060] The maintenance ratio Y-2 of the specific surface area is more preferably 0.87 or higher, and even more preferably 0.89 or higher. The maintenance ratio Y-2 of the specific surface area is preferable to be as large as possible, but for example, it should be 1.03 or less, 1.01 or less, etc. The maintenance ratio Y-2 of the specific surface area is more preferably 0.87 or more and 1.03 or less, and even more preferably 0.89 or more and 1.01 or less.

[0061] The specific surface area A-2 is more preferably 22 m². 2 / g or more, more preferably 24m 2 It is 1 / g or more. The specific surface area A-2 is preferable as it is larger, for example, 78 m². 2 / g or less, 76m 2 It is less than / g, etc. The specific surface area A-2 is more preferably 22 m². 2 / g or more 78m 2 / g or less, more preferably 24m 2 / g or more 76m 2 It is less than / g. The aforementioned specific surface area A-2 is 22m² 2 If the value is 1 / g or higher, the specific surface area after crushing and heat treatment at 1000°C for 3 hours can be said to be sufficiently large.

[0062] The specific surface area B-2 is more preferably 22 m². 2 / g or more, more preferably 24m 2 It is 1 / g or more. The specific surface area B-2 is preferable as it is larger, for example, 78 m². 2 / g or less, 76m 2 It is less than / g, etc. The specific surface area B-2 is more preferably 22 m². 2 / g or more 78m 2 / g or less, more preferably 24m 2 / g or more 76m 2 It is less than / g. The aforementioned specific surface area B-2 is 22m² 2 If the value is 1 / g or more, the specific surface area before crushing and after heat treatment at 1000°C for 3 hours can be said to be sufficiently large.

[0063] <Percentage of maintenance of specific surface area before heat treatment before and after crushing> When the specific surface area of ​​the zirconia-based porous material after crushing treatment (before heat treatment) under the following crushing treatment conditions is defined as specific surface area A-3, and the specific surface area before crushing treatment (before heat treatment) is defined as specific surface area B-3, It is preferable that the maintenance ratio Y-3 of the specific surface area, represented by the following formula (7), is 0.85 or more and 1.05 or less. <Crushing process conditions> 30 g of zirconia-based porous material and 300 ml of pure water are placed in a 500 ml beaker and dispersed using an ultrasonic homogenizer for 5 minutes. Then, it is dried at 110°C for 24 hours. The dispersion using the ultrasonic homogenizer is performed at 550 W and 37% amplitude. More specifically, a "Sonifier SFX550" (Emerson Japan Co., Ltd.) is used as the ultrasonic homogenizer, and the dispersion is performed at 550 W and 37% amplitude. <Maintenance ratio of specific surface area Y-3> [(Specific surface area A-3) / (Specific surface area B-3)] Formula (7)

[0064] If the maintenance ratio of the specific surface area Y-3 is between 0.85 and 1.05, it can be said that the specific surface area has not changed significantly even after the crushing treatment.

[0065] The maintenance ratio Y-3 of the specific surface area is more preferably 0.87 or higher, and even more preferably 0.89 or higher. The maintenance ratio Y-3 of the specific surface area is preferable to be as large as possible, but for example, it should be 1.03 or less, 1.01 or less, etc. The maintenance ratio Y-3 of the specific surface area is more preferably 0.87 or more and 1.03 or less, and even more preferably 0.89 or more and 1.01 or less.

[0066] The specific surface area A-3 is more preferably 32 m². 2 / g or more, more preferably 34m 2 It is 1 / g or more. The specific surface area A-3 is preferable as it is larger, for example, 118 m². 2 / g or less, 116m 2 It is less than / g, etc. The specific surface area A-3 is more preferably 32 m². 2 / g or more 118m 2 / g or less, more preferably 34m 2 / g or more 116m 2 It is less than / g. The aforementioned specific surface area A-3 is 32m² 2 If the value is 1 / g or higher, the specific surface area after crushing can be considered sufficiently large.

[0067] The specific surface area B-3 is more preferably 32 m². 2 / g or more, more preferably 34m 2 It is 1 / g or more. The specific surface area B-3 is preferable as it is larger, for example, 118 m². 2 / g or less, 116m 2 It is less than / g, etc. The specific surface area B-3 is more preferably 32 m². 2 / g or more 118m 2 / g or less, more preferably 34m 2 / g or more 116m 2 It is less than / g. The aforementioned specific surface area B-3 is 32m² 2 If the value is 1 / g or more, it can be said that the specific surface area before crushing and before heat treatment is sufficiently large.

[0068] Details of the method for measuring the specific surface area are as described in the examples.

[0069] <Particle size D after crushing treatment> 50 > The zirconia-based porous material has a particle size D after crushing treatment under the following crushing treatment conditions. 50 It is preferable that the particle size is between 1.0 μm and 50.0 μm. <Crushing process conditions> 30 g of zirconia-based porous material and 300 ml of pure water are placed in a 500 ml beaker and dispersed using an ultrasonic homogenizer for 5 minutes. The dispersion using the ultrasonic homogenizer is performed at 550 W and 37% amplitude. More specifically, a "Sonifier SFX550" (Emerson Japan Co., Ltd.) is used as the ultrasonic homogenizer, and the dispersion is performed at 550 W and 37% amplitude. Particle size D after the crushing treatment 50 If the particle size is between 1.0 μm and 50.0 μm, it can be suitably coated onto the honeycomb after the grinding process.

[0070] Particle size D after the crushing treatment 50 The particle size is more preferably 1.2 μm or larger, and even more preferably 1.4 μm or larger. Particle size D after the crushing treatment 50 The particle size is more preferably 49.8 μm or less, and even more preferably 49.6 μm or less. Particle size D after the crushing treatment 50 The particle size is more preferably 1.2 μm to 49.8 μm, and even more preferably 1.4 μm to 49.6 μm.

[0071] <Particle size D before crushing treatment> 50 > Particle size D of the zirconia-based porous material before crushing treatment 50 The particle size D before the crushing treatment is preferably 1.2 μm or more and 49.8 μm or less. 50 If the particle size is between 1.2 μm and 49.8 μm, it can be suitably coated onto the honeycomb after the grinding process.

[0072] Particle size D before the crushing treatment 50 The particle size is more preferably 1.2 μm or larger, and even more preferably 1.4 μm or larger. Particle size D before the crushing treatment 50 The particle size is more preferably 49.8 μm or less, and even more preferably 49.6 μm or less. Particle size D before the crushing treatment 50 The particle size is more preferably 1.2 μm to 49.8 μm, and even more preferably 1.4 μm to 49.6 μm.

[0073] The particle size D 50 Details of the measurement method are as described in the examples.

[0074] <Composition> The zirconia-based porous material contains zirconia. The zirconia content is 40% by mass or more when the total mass of the zirconia-based porous material is considered to be 100% by mass. Because the zirconia content is 40% by mass or more, it can be suitably used as a catalyst support.

[0075] The zirconia content is preferably 40% by mass or more, more preferably 45% by mass or more, and even more preferably 50% by mass or more, when the entire zirconia-based porous body is considered to be 100% by mass. There is no particular upper limit to the zirconia content, but the zirconia content is preferably 99% by mass or less, and more preferably 98% by mass or less.

[0076] The zirconia-based porous material contains one or more oxides selected from rare earth elements.

[0077] The content of rare earth element oxides is between 5% and 60% by mass, when the entire zirconia-based porous material is considered to be 100% by mass. Because it contains rare earth element oxides in the range of 5% to 60% by mass, the decrease in specific surface area when exposed to high temperatures can be suppressed, both before and after the crushing treatment.

[0078] The content of rare earth element oxides is preferably 6% by mass or more, more preferably 7% by mass or more, even more preferably 10% by mass or more, particularly preferably 15% by mass or more, and especially preferably 20% by mass or more, when the entire zirconia-based porous body is considered to be 100% by mass. The content of rare earth element oxides is preferably 59% by mass or less, more preferably 58% by mass or less, even more preferably 55% by mass or less, and particularly preferably 50% by mass or less, when the entire zirconia-based porous body is considered to be 100% by mass. The content of rare earth element oxides is preferably 6% to 59% by mass, more preferably 7% to 58% by mass, even more preferably 10% to 55% by mass, particularly preferably 15% to 55% by mass, and especially preferably 20% to 55% by mass or 20% to 50% by mass, when the entire zirconia-based porous body is considered as 100% by mass.

[0079] The aforementioned rare earth elements are Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. However, it is preferable that the zirconia-based porous material does not contain Pm. In other words, it is more preferable that the zirconia-based porous material contains one or more oxides selected from rare earth elements other than Pm.

[0080] Because it contains one or more oxides selected from rare earth elements, it can suppress the decrease in specific surface area when exposed to high temperatures, both before and after the crushing treatment.

[0081] Among the rare earth elements mentioned above, Y (yttrium), La (lanthanum), Ce (cerium), Nd (neodymium), and Pr (praseodymium) are preferred. In other words, the zirconia-based porous material preferably contains one or more oxides selected from the group consisting of lanthanum oxide, cerium oxide, neodymium oxide, praseodymium oxide, and yttrium oxide.

[0082] The zirconia-based porous material comprises, in addition to zirconia and the oxides of the rare earth elements, A) One or more oxides selected from the group consisting of Al, In, Si, Sn, Bi, P, and Zn. B) Transition metal oxides (excluding oxides of rare earth elements and noble metal elements) C) Alkaline earth metal oxides D) platinum group It may contain oxides of one or more elements selected from the group consisting of the following. Hereinafter, the elements indicated in A) to D) will be referred to as "other elements" in this specification. If the zirconia-based porous body contains oxides of the other elements, the content of the oxides of the other elements may be 0.1% by mass or more in terms of oxides, when the entire zirconia-based porous body is considered to be 100% by mass. There is no particular upper limit on the content of the oxides of the other elements, but it may be 20% by mass or less, 10% by mass or less, 7% by mass or less, 5% by mass or less, etc. Examples of the transition metals include Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, Ta, W, and Ag. Examples of the alkaline earth metals include Mg, Ca, Sr, and Ba. Examples of the early platinum group metals include Rh, Pd, Pt, and Ir.

[0083] In the zirconia-based porous material, the total content of zirconia and rare earth oxides is preferably 80% by mass or more and 100% by mass or less. More preferably, the total content of zirconia and rare earth oxides is 85% by mass or more, and even more preferably 90% by mass or more. More preferably, the total content of zirconia and rare earth oxides is 99% by mass or less, and even more preferably 98% by mass or less.

[0084] Preferred composition ratios for the zirconia-based porous material include combinations that do not exceed 100% in total, as exemplified in (1) to (4) below. (1) Zirconia; 40% by mass or more, 95% by mass or less Rare earth oxide; 5% by mass or more and 60% by mass or less Oxides of other elements; 0% to 20% by mass (2) Zirconia; 43% by mass or more and 90% by mass or less Rare earth oxide; 10% by mass or more and 55% by mass or less Oxides of other elements; 1% by mass or more and 15% by mass or less (3) Zirconia; 45% by mass or more, 75% by mass or less Rare earth oxide; 15% by mass or more and 50% by mass or less Oxides of other elements; 1% by mass or more, and 10% by mass or less. (4) Zirconia; 50% by mass or more, 70% by mass or less Rare earth oxide; 16% by mass or more and 45% by mass or less Oxides of other elements; 1% by mass or more, and 5% by mass or less.

[0085] [Method for manufacturing zirconia-based porous materials] The following describes an example of a method for producing a zirconia-based porous material. However, the method for producing a zirconia-based porous material according to the present invention is not limited to the following example.

[0086] The method for producing a zirconia-based porous body according to this embodiment is as follows: Step 1 involves simultaneously adding a zirconium salt solution and a sulfate chlorine agent to heated water to obtain a basic zirconium sulfate-containing slurry, Step 2 involves removing unreacted zirconium salts and soluble zirconium salts, Step 3 involves adding a rare earth salt solution to the basic zirconium sulfate-containing slurry obtained in step 2, and then adding an alkali to obtain a zirconium-containing hydroxide. The process includes step 4, in which the zirconium-containing hydroxide obtained in step 3 is heat-treated to obtain a zirconia-based porous body.

[0087] <Process 1> In the method for producing a zirconia-based porous body according to this embodiment, first, a zirconium salt solution and a sulfated chlorine agent are simultaneously added to heated water to obtain a basic zirconium sulfate-containing slurry.

[0088] By simultaneously adding a zirconium salt solution and a sulfate chlorinator to heated water and uniformly chlorinating it, the pore size distribution of basic zirconium sulfate can be controlled to satisfy conditions (1) and (2) above, and only specific pores, which are important for suppressing the decrease in specific surface area due to heating, can be formed. During the crushing process, the particles break down starting from voids, especially macropores of 300 nm or more, so particles without unnecessary pores become less prone to crushing.

[0089] The water mentioned above is not particularly limited, and can include ion-exchanged water, pure water, distilled water, purified water, etc.

[0090] The heating temperature of the water is not particularly limited, but it is preferably 85°C to 100°C. The heating temperature of the water is more preferably 87°C or higher, and even more preferably 89°C or higher. The heating temperature of the water is more preferably 98°C or lower, and even more preferably 96°C or lower. The heating temperature of the water is more preferably 87°C to 99°C, and even more preferably 89°C to 98°C.

[0091] Any zirconium salt that supplies zirconium ions can be used, such as zirconium oxynitrate, zirconium oxychloride, zirconium nitrate, or their hydrates. These can be used individually or in combination of two or more.

[0092] The solvent used to prepare the zirconium salt solution should be selected according to the type of zirconium salt. Water (pure water, deionized water) is usually preferred.

[0093] The concentration of the zirconium salt solution is not particularly limited, but it is generally desirable that it contains 5 to 250 g (especially 20 to 150 g) of zirconium oxide (ZrO2) per 1000 g of solvent.

[0094] The sulfated agent is not limited to any agent that reacts with zirconium ions to produce a sulfate (i.e., a sulfated reagent), and examples include sodium sulfate, potassium sulfate, and ammonium sulfate. The sulfated agent may be in powder or solution form, but a solution (especially an aqueous solution) is preferred. When using a solution, the concentration of the solution can be set as appropriate.

[0095] The sulfated chlorine agent to be added is sulfate (SO4 2- It is preferable to add ) / ZrO2 such that the weight ratio is 0.3 or more and 0.7 or less.

[0096] When adding a zirconium salt solution and a sulfated chlorine agent to heated water simultaneously, the rate of addition is not particularly limited as long as uniform sulfuric acid oxidation can be achieved. However, for example, when adding 400g to 600g of a 15% by mass zirconium oxychloride solution and 300g to 400g of 15% sodium sulfate (sulfated chlorine agent), it is preferable to add them over a period of 30 to 90 minutes.

[0097] When adding the zirconium salt solution and the sulfated chloride agent to heated water simultaneously, the temperatures of the zirconium salt solution and the sulfated chloride agent are not particularly limited, but are preferably 10°C to 90°C, and more preferably 20°C to 80°C.

[0098] After adding the zirconium salt solution and sulfate chlorine agent to heated water, the water may be kept at the temperature of the heated water for 0 to 60 minutes, if necessary.

[0099] Subsequently, by allowing it to cool to room temperature, a slurry containing basic zirconium sulfate is obtained.

[0100] <Process 2> Next, the unreacted zirconium salt and the soluble zirconium salt are removed. While not particularly limited, one method for removing the unreacted zirconium salt and the soluble zirconium salt is decantation to remove the supernatant.

[0101] By removing unreacted zirconium salts and soluble zirconium salts, the formation of fine particles during neutralization and the formation of coarse particles due to the aggregation of secondary particles can be prevented, resulting in a zirconia-based porous material that is less prone to breaking down and exhibits minimal changes in pore size distribution during the crushing process.

[0102] <Process 3> Next, a rare earth salt solution is added to the basic zirconium sulfate-containing slurry obtained in step 2 (the basic zirconium sulfate-containing slurry from which unreacted zirconium salts and soluble zirconium salts have been removed). At this time, if necessary, a salt solution or compound of one or more metals selected from the group consisting of other elements may be added. After that, an alkali is added to obtain a zirconium-containing hydroxide.

[0103] The alkali is not limited to the above, and for example, ammonium hydroxide, ammonium bicarbonate, sodium hydroxide, potassium hydroxide, etc. can be used. Among these, sodium hydroxide is preferred from an industrial cost perspective.

[0104] The amount of alkali added is not particularly limited, as long as it can be used to form zirconium-containing hydroxide (zirconium hydroxide) as a precipitate from the basic zirconium sulfate solution. Typically, alkali is added so that the pH of the solution becomes 11 or higher, preferably 12 or higher.

[0105] Next, the zirconium-containing hydroxide is recovered by solid-liquid separation. For example, filtration, centrifugation, and decantation can be used.

[0106] After recovering the zirconium-containing hydroxide, it is preferable to wash the zirconium-containing hydroxide with water to remove any adhering impurities.

[0107] The zirconium-containing hydroxide may be dried by natural drying or heat drying.

[0108] <Step 4> Next, the zirconium-containing hydroxide obtained in step 3 is heat-treated (calcined) to obtain a zirconia-based porous body. The heat treatment temperature is not particularly limited, but it is preferably around 400 to 900°C for 1 to 10 hours. The heat treatment atmosphere is preferably in air or an oxidizing atmosphere.

[0109] The method for producing a zirconia-based porous body according to this embodiment has been described above. [Examples]

[0110] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. In the zirconia-based porous bodies obtained in the examples and comparative examples, hafnium is contained as an unavoidable impurity at a concentration of 1 to 3% by mass relative to the zirconium (calculated by the following formula (X)). <Formula (X)> ([Mass of hafnium] / ([Mass of zirconium]+[Mass of hafnium]))×100(%)

[0111] The maximum and minimum values ​​of the content of each component shown in the following examples should be considered as the preferred minimum and preferred maximum values ​​of the present invention, regardless of the content of other components. Furthermore, the maximum and minimum values ​​of the measurements shown in the following examples should be considered as the preferred minimum and maximum values ​​of the present invention, regardless of the content (composition) of each component.

[0112] [Fabrication of zirconia-based porous materials] (Example 1) 188 g of zirconium oxychloride octahydrate (equivalent to 72 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. To 600 g of deionized water heated to 90°C, 480 g of the zirconium oxychloride solution heated to 90°C and 360 g of 15% sodium sulfate (sulfate agent) heated to 90°C were simultaneously added over 60 minutes, and the mixture was held for another 60 minutes to obtain 5% by mass of basic zirconium sulfate. The mixture was then allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate (Step 1).

[0113] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass (Step 2).

[0114] Next, 210 g of cerium nitrate solution (210 g in terms of CeO2), 20 g of lanthanum nitrate solution (2 g in terms of La2O3), and 50 g of neodymium nitrate solution (5 g in terms of Nd2O3) were added to the basic zirconium sulfate-containing slurry obtained in step 2. Then, 500 g of 25% sodium hydroxide (alkali for neutralization) was added over 60 minutes to generate zirconium-containing hydroxide (hydroxide precipitate) (step 3).

[0115] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0116] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 700°C for 5 hours to obtain the zirconia-based porous material according to Example 1 (Step 4).

[0117] (Example 2) 144 g of zirconium oxychloride octahydrate (equivalent to 55 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. To 458 g of ion-exchanged water heated to 95°C, 367 g of the zirconium oxychloride solution heated to 95°C and 275 g of 15% sodium sulfate (sulfate agent) heated to 95°C were simultaneously added over 60 minutes, and the mixture was held for another 60 minutes to obtain 7% by mass of basic zirconium sulfate. The mixture was then allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate (Step 1).

[0118] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass (Step 2).

[0119] Next, 400 g of cerium nitrate solution (equivalent to 40 g of CeO2) and 50 g of lanthanum nitrate solution (equivalent to 5 g of La2O3) were added to the basic zirconium sulfate-containing slurry obtained in step 2. Then, 500 g of 25% sodium hydroxide (neutralizing alkali) was added over 60 minutes to generate zirconium-containing hydroxide (hydroxide precipitate) (step 3).

[0120] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0121] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 750°C for 5 hours to obtain the zirconia-based porous material according to Example 2 (Step 4).

[0122] (Example 3) 131 g of zirconium oxychloride octahydrate (equivalent to 50 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. To 450 g of deionized water heated to 95°C, 360 g of the zirconium oxychloride solution heated to 95°C and 270 g of 15% sodium sulfate (sulfate agent) heated to 95°C were simultaneously added over 60 minutes, and the mixture was held for another 60 minutes to obtain 5% by mass of basic zirconium sulfate. The mixture was then allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate (Step 1).

[0123] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass (Step 2).

[0124] Next, 400 g of cerium nitrate solution (equivalent to 40 g of CeO2), 50 g of lanthanum nitrate solution (equivalent to 5 g of La2O3), and 50 g of yttrium nitrate solution (equivalent to 5 g of Y2O3) were added to the basic zirconium sulfate-containing slurry obtained in step 2. Then, 500 g of 25% sodium hydroxide (neutralizing alkali) was added over 60 minutes to generate zirconium-containing hydroxide (hydroxide precipitate) (step 3).

[0125] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0126] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 900°C for 5 hours to obtain the zirconia-based porous material according to Example 3 (Step 4).

[0127] (Example 4) 162 g of zirconium oxychloride octahydrate (equivalent to 62 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. To 517 g of deionized water heated to 90°C, 413 g of the zirconium oxychloride solution heated to 90°C and 310 g of 15% sodium sulfate (sulfate agent) heated to 90°C were simultaneously added over 30 minutes. The mixture was then held for another 60 minutes to obtain 5% by mass of basic zirconium sulfate. The mixture was then allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate. (Step 1).

[0128] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass (Step 2).

[0129] Next, 300 g of cerium nitrate solution (equivalent to 30 g of CeO2), 40 g of lanthanum nitrate solution (equivalent to 4 g of La2O3), and 40 g of neodymium nitrate solution (equivalent to 4 g of Nd2O3) were added to the basic zirconium sulfate-containing slurry obtained in step 2. Then, 500 g of 25% sodium hydroxide (neutralizing alkali) was added over 60 minutes to generate zirconium-containing hydroxide (hydroxide precipitate) (step 3).

[0130] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0131] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 750°C for 5 hours to obtain the zirconia-based porous material according to Example 4 (Step 4).

[0132] (Example 5) 118 g of zirconium oxychloride octahydrate (equivalent to 45 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. To 375 g of ion-exchanged water heated to 90°C, 300 g of the zirconium oxychloride solution heated to 90°C and 225 g of 15% sodium sulfate (sulfate agent) heated to 90°C were simultaneously added over 90 minutes, and the mixture was held for another 60 minutes to obtain 5% by mass of basic zirconium sulfate. The mixture was then allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate (Step 1).

[0133] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass (Step 2).

[0134] Next, 450 g of cerium nitrate solution (equivalent to 45 g of CeO2), 50 g of lanthanum nitrate solution (equivalent to 5 g of La2O3), and 50 g of neodymium nitrate solution (equivalent to 5 g of Nd2O3) were added to the basic zirconium sulfate-containing slurry obtained in step 2. Then, 500 g of 25% sodium hydroxide (neutralizing alkali) was added over 60 minutes to generate zirconium-containing hydroxide (hydroxide precipitate) (step 3).

[0135] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0136] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 800°C for 5 hours to obtain the zirconia-based porous material according to Example 5 (Step 4).

[0137] (Example 6) 209 g of zirconium oxychloride octahydrate (equivalent to 80 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. To 667 g of ion-exchanged water heated to 90°C, 533 g of the zirconium oxychloride solution heated to 90°C and 400 g of 15% sodium sulfate (sulfate agent) heated to 90°C were simultaneously added over 60 minutes, and the mixture was held for another 60 minutes to obtain 5% by mass of basic zirconium sulfate. The mixture was then allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate (Step 1).

[0138] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass (Step 2).

[0139] Next, 50 g of cerium nitrate solution (equivalent to 5 g of CeO2), 500 g of lanthanum nitrate solution (equivalent to 5 g of La2O3), 50 g of neodymium nitrate solution (equivalent to 5 g of Nd2O3), and 50 g of yttrium nitrate solution (equivalent to 5 g of Y2O3) were added to the basic zirconium sulfate-containing slurry obtained in step 2. Then, 500 g of 25% sodium hydroxide (alkali for neutralization) was added over 60 minutes to generate zirconium-containing hydroxide (hydroxide precipitate) (step 3).

[0140] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0141] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 700°C for 5 hours to obtain the zirconia-based porous material according to Example 6 (Step 4).

[0142] (Example 7) 209 g of zirconium oxychloride octahydrate (equivalent to 80 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. To 1733 g of ion-exchanged water heated to 90°C, 533 g of the zirconium oxychloride solution heated to 90°C and 400 g of 15% sodium sulfate (sulfate agent) heated to 90°C were simultaneously added over 60 minutes, and the mixture was held for another 60 minutes to obtain 5% by mass of basic zirconium sulfate. The mixture was then allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate (Step 1).

[0143] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass (Step 2).

[0144] Next, 50 g of cerium nitrate solution (equivalent to 5 g of CeO2), 500 g of lanthanum nitrate solution (equivalent to 5 g of La2O3), 50 g of neodymium nitrate solution (equivalent to 5 g of Nd2O3), and 50 g of yttrium nitrate solution (equivalent to 5 g of Y2O3) were added to the basic zirconium sulfate-containing slurry obtained in step 2. Then, 500 g of 25% sodium hydroxide (alkali for neutralization) was added over 60 minutes to generate zirconium-containing hydroxide (hydroxide precipitate) (step 3).

[0145] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0146] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 700°C for 5 hours to obtain the zirconia-based porous material according to Example 7 (Step 4).

[0147] (Example 8) 209 g of zirconium oxychloride octahydrate (equivalent to 80 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. Step 1) involved simultaneously adding 533 g of zirconium oxychloride solution heated to 90°C and 400 g of 15% sodium sulfate (sulfate agent) heated to 90°C to 210 g of deionized water heated to 90°C over 60 minutes, and holding for another 60 minutes to obtain 3% by mass of basic zirconium sulfate. The mixture was then allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate.

[0148] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass (Step 2).

[0149] Next, 50 g of cerium nitrate solution (equivalent to 5 g of CeO2), 500 g of lanthanum nitrate solution (equivalent to 5 g of La2O3), 50 g of neodymium nitrate solution (equivalent to 5 g of Nd2O3), and 50 g of yttrium nitrate solution (equivalent to 5 g of Y2O3) were added to the basic zirconium sulfate-containing slurry obtained in step 2. Then, 500 g of 25% sodium hydroxide (alkali for neutralization) was added over 60 minutes to generate zirconium-containing hydroxide (hydroxide precipitate) (step 3).

[0150] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0151] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 900°C for 5 hours to obtain the zirconia-based porous material according to Example 8 (Step 4).

[0152] (Example 9) 157 g of zirconium oxychloride octahydrate (equivalent to 59.9 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. To 500 g of deionized water heated to 95°C, 400 g of the zirconium oxychloride solution heated to 95°C and 300 g of 15% sodium sulfate (sulfate agent) heated to 95°C were simultaneously added over 90 minutes, and the mixture was held for another 60 minutes to obtain 5 wt% basic zirconium sulfate. The mixture was then allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate (Step 1).

[0153] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass (Step 2).

[0154] Next, to the basic zirconium sulfate-containing slurry obtained in step 2, 320 g of cerium nitrate solution (equivalent to 32 g of CeO2), 20 g of lanthanum nitrate solution (equivalent to 2 g of La2O3), 20 g of neodymium nitrate solution (equivalent to 2 g of Nd2O3), and 20 g of praseodymium nitrate solution (Pr6O2) were added.11 2 g of yttrium nitrate solution (equivalent to 2 g of Y2O3) and 1 g of iron nitrate solution (equivalent to 0.1 g of Fe2O3) were added. Next, 500 g of 25% sodium hydroxide (neutralizing alkali) was added over 60 minutes to generate zirconium-containing hydroxide (hydroxide precipitate) (Step 3).

[0155] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0156] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 600°C for 5 hours to obtain the zirconia-based porous material according to Example 9 (Step 4).

[0157] (Example 10) 157 g of zirconium oxychloride octahydrate (equivalent to 63 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. To 165 g of ion-exchanged water heated to 95°C, 420 g of zirconium oxychloride solution heated to 95°C and 315 g of 15% sodium sulfate (sulfate agent) heated to 95°C were simultaneously added over 60 minutes. The mixture was then held for another 60 minutes to obtain 7% by mass of basic zirconium sulfate. The mixture was then allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate (Step 1).

[0158] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass (Step 2).

[0159] Next, 120 g of lanthanum nitrate solution (equivalent to 12 g of La2O3) and 250 g of yttrium nitrate solution (equivalent to 25 g of Y2O3) were added to the basic zirconium sulfate-containing slurry obtained in step 2. Then, 500 g of 25% sodium hydroxide (neutralizing alkali) was added over 60 minutes to generate zirconium-containing hydroxide (hydroxide precipitate) (step 3).

[0160] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

[0161] The obtained hydroxide was dried at 105 °C for 24 hours. The dried hydroxide was heat-treated at 700 °C for 5 hours in the air to obtain a zirconia-based porous body according to Example 10 (Step 4).

[0162] (Comparative Example 1) 187 g of zirconium oxychloride octahydrate (ZrO₂ equivalent: 72 g) was dissolved in ion-exchanged water. Next, it was prepared so that the acid concentration was 0.67 N and the ZrO₂ concentration was 4 w / v% with 35% hydrochloric acid and ion-exchanged water. The obtained solution was put into an autoclave, the pressure was set to 2×10 5 Pa, the temperature was raised to 120 °C, 1065 g of 5% sodium sulfate (sulfate chlorinating agent) was added at the same temperature, and it was further held for 15 minutes. After sulfate chlorination, it was allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate. 210 g of cerium nitrate solution (CeO₂ equivalent: 21 g), 20 g of lanthanum nitrate solution (La₂O₃ equivalent: 2 g), and 50 g of neodymium nitrate solution (Nd₂O₃ equivalent: 5 g) were added to the obtained slurry containing basic zirconium sulfate. Next, 500 g of 25% sodium hydroxide (alkali for neutralization) was added over 60 minutes. By this neutralization, zirconium hydroxide was produced. Next, the slurry containing zirconium hydroxide was filtered and washed with water, and then calcined at 600 °C for 5 hours to obtain an oxide. The oxide was pulverized in a mortar until it became 20 μm or less. This was used as the zirconia-based porous body according to Comparative Example 1.

[0163] (Comparative Example 2) 213 g of 25% aqueous sodium sulfate solution and 450 g of zirconium oxychloride aqueous solution equivalent to 16% in terms of ZrO₂ were each heated to 95 °C. Thereafter, the heated aqueous solutions were contacted and mixed over 3 hours so that the SO4 2- / ZrO₂ weight ratio of the mixed solution was maintained at 0.50. The reaction solution containing basic zirconium sulfate obtained by contact and mixing was held at 95 °C for 4 hours for aging to obtain basic zirconium sulfate. Next, the matured reaction solution containing basic zirconium sulfate was cooled to room temperature, and then 105 g of cerium nitrate aqueous solution equivalent to 20% CeO2, 8.5 g of lanthanum nitrate aqueous solution (manufactured by Wako Pure Chemical Industries) equivalent to 20% La2O3, and 26.5 g of neodymium nitrate aqueous solution equivalent to 20% Nd2O3 were added and mixed uniformly. Next, a 25% sodium hydroxide aqueous solution was added to the resulting mixed solution and neutralized until the pH reached 13 or higher, thereby generating a hydroxide precipitate. The obtained hydroxide precipitate was filtered, thoroughly washed with water, and the resulting hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 600°C for 5 hours to obtain a zirconia-based porous material according to Comparative Example 2.

[0164] (Comparative Example 3) 152 g of zirconium oxynitrate dihydrate (equivalent to 70 g of ZrO2) was dissolved in deionized water to prepare a zirconium salt solution with a ZrO2 concentration of 10 wt / v%. The obtained solution was placed in an autoclave and heated to 120°C, held for 1 hour, then 1250 g of 5% sodium sulfate (sulfate chloride) was added, and the mixture was held for another 60 minutes. After that, it was allowed to cool to room temperature (25°C) to obtain a slurry containing basic zirconium sulfate. 200 g of cerium nitrate solution (equivalent to 20 g of CeO2), 20 g of lanthanum nitrate solution (equivalent to 2 g of La2O3), and 80 g of neodymium nitrate solution (equivalent to 8 g of Nd2O3) were added to a slurry containing basic zirconium sulfate. Next, 500g of 25% sodium hydroxide (neutralizing alkali) was added over 60 minutes to generate a hydroxide precipitate (zirconium hydroxide-containing slurry). The obtained hydroxide precipitate was filtered, thoroughly washed with water, and the resulting hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated (calcined) in air at 700°C for 5 hours to obtain a zirconia-based porous material according to Comparative Example 3.

[0165] (Comparative Example 4) 144 g of zirconium oxychloride octahydrate (equivalent to 55 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 20% by mass, thereby obtaining a zirconium oxychloride solution. To 130 g of deionized water heated to 90°C, 270 g of zirconium oxychloride solution heated to 90°C and 206 g of 20% sodium sulfate (sulfate agent) heated to 90°C were simultaneously added over 60 minutes. The mixture was then held for another 60 minutes to obtain 9 wt% basic zirconium sulfate. After that, the mixture was allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate.

[0166] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass.

[0167] Next, 400 g of cerium nitrate solution (equivalent to 40 g of CeO2) and 50 g of neodymium nitrate solution (equivalent to 5 g of La2O3) were added to the obtained basic zirconium sulfate-containing slurry. Then, 500 g of 25% sodium hydroxide (neutralizing alkali) was added over 60 minutes to generate a hydroxide precipitate.

[0168] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0169] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 900°C for 5 hours to obtain a zirconia-based porous material according to Comparative Example 4.

[0170] (Comparative Example 5) 131 g of zirconium oxychloride octahydrate (equivalent to 50 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. To 450 g of deionized water heated to 90°C, 360 g of the zirconium oxychloride solution heated to 90°C and 270 g of 15% sodium sulfate (sulfate agent) heated to 90°C were simultaneously added over 5 minutes. The mixture was then held for another 60 minutes to obtain 5% by mass of basic zirconium sulfate. After that, the mixture was allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate.

[0171] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass.

[0172] Next, 400 g of cerium nitrate solution (equivalent to 40 g of CeO2), 50 g of lanthanum nitrate solution (equivalent to 5 g of La2O3), and 50 g of yttrium nitrate solution (equivalent to 5 g of Y2O3) were added to the obtained basic zirconium sulfate-containing slurry. Then, 500 g of 25% sodium hydroxide (neutralizing alkali) was added over 60 minutes to generate a hydroxide precipitate.

[0173] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0174] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 900°C for 5 hours to obtain a zirconia-based porous material according to Comparative Example 5.

[0175] (Comparative Example 6) 209 g of zirconium oxychloride octahydrate (equivalent to 80 g of ZrO2) was dissolved in deionized water to prepare a ZrO2 concentration of 5% by mass. 400 g of 15% sodium sulfate (sulfate agent) was added over 60 minutes, and the mixture was heated to 90°C and held for 60 minutes. After that, it was allowed to cool to room temperature to obtain a basic zirconium sulfate-containing slurry. The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass.

[0176] Next, 50 g of cerium nitrate solution (equivalent to 5 g of CeO2), 50 g of lanthanum nitrate solution (equivalent to 5 g of La2O3), 50 g of neodymium nitrate solution (equivalent to 5 g of Nd2O3), and 50 g of yttrium nitrate solution (equivalent to 5 g of Y2O3) were added to the obtained basic zirconium sulfate-containing slurry. Then, 500 g of 25% sodium hydroxide (neutralizing alkali) was added over 60 minutes to generate a hydroxide precipitate.

[0177] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0178] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 700°C for 5 hours to obtain a zirconia-based porous material according to Comparative Example 6.

[0179] (Comparative Example 7) 162 g of zirconium oxychloride octahydrate (equivalent to 62 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. To 517 g of deionized water heated to 80°C, 413 g of zirconium oxychloride solution heated to 80°C and 310 g of 15% sodium sulfate (sulfate agent) heated to 80°C were simultaneously added over 60 minutes. The mixture was then held for another 60 minutes to obtain 5% by mass of basic zirconium sulfate. The mixture was then allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate.

[0180] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass.

[0181] Next, 300 g of cerium nitrate solution (equivalent to 30 g of CeO2), 40 g of lanthanum nitrate solution (equivalent to 4 g of La2O3), and 40 g of neodymium nitrate solution (equivalent to 4 g of Nd2O3) were added to the obtained basic zirconium sulfate-containing slurry. Then, 500 g of 25% sodium hydroxide (neutralizing alkali) was added over 60 minutes to generate a hydroxide precipitate.

[0182] The resulting hydroxide precipitate was then filtered and thoroughly washed with water.

[0183] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 750°C for 5 hours to obtain a zirconia-based porous material according to Comparative Example 7.

[0184] (Comparative Example 8) 118 g of zirconium oxychloride octahydrate (equivalent to 45 g of ZrO2) was dissolved in deionized water to prepare a solution with a ZrO2 concentration of 15% by mass, thereby obtaining a zirconium oxychloride solution. To 1725 g of deionized water heated to 90°C, 300 g of the zirconium oxychloride solution heated to 90°C and 225 g of 15% sodium sulfate (sulfate agent) heated to 90°C were simultaneously added over 90 minutes. The mixture was then held for another 60 minutes to obtain 2% by mass of basic zirconium sulfate. The mixture was then allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate.

[0185] The obtained basic zirconium sulfate-containing slurry was decanted, and the supernatant was removed to remove unreacted zirconium salts and soluble zirconium salts. Then, deionized water was added to a concentration of 5% by mass.

[0186] Next, 450 g of cerium nitrate solution (equivalent to 45 g of CeO2), 50 g of lanthanum nitrate solution (equivalent to 5 g of La2O3), and 50 g of neodymium nitrate solution (equivalent to 5 g of Nd2O3) were added to the basic zirconium sulfate-containing slurry. Then, 500 g of 25% sodium hydroxide (neutralizing alkali) was added over 60 minutes to generate a hydroxide precipitate.

[0187] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

[0188] The obtained hydroxide was dried at 105 °C for 24 hours. The dried hydroxide was heat-treated at 700 °C in the air for 5 hours to obtain a zirconia-based porous body according to Comparative Example 8.

[0189] (Comparative Example 9) 157 g of zirconium oxychloride octahydrate (ZrO₂ equivalent: 59.9 g) was dissolved in ion-exchanged water to prepare a zirconium oxychloride solution with a ZrO₂ concentration of 15% by mass. To 500 g of ion-exchanged water heated to 90 °C, 400 g of the zirconium oxychloride solution heated to 90 °C and 300 g of 15% sodium sulfate (sulfate chlorinating agent) heated to 90 °C were simultaneously added over 120 minutes, and then held for 60 minutes to obtain 5% basic zirconium sulfate. Thereafter, it was allowed to cool to room temperature to obtain a slurry containing basic zirconium sulfate.

[0190] The obtained slurry containing basic zirconium sulfate was decanted to remove the supernatant, and unreacted zirconium salts and soluble zirconium salts were removed. Thereafter, ion-exchanged water was added to make it 5% by mass.

[0191] Next, 320 g of a cerium nitrate solution (CeO₂ equivalent: 32 g), 20 g of a lanthanum nitrate solution (La₂O₃ equivalent: 2 g), 20 g of a neodymium nitrate solution (Nd₂O₃ equivalent: 2 g), 20 g of a praseodymium nitrate solution (Pr₆O 11 equivalent: 2 g), 20 g of a yttrium nitrate solution (Y₂O₃ equivalent: 2 g), and 1 g of an iron nitrate solution (Fe₂O₃ equivalent: 0.1 g) were added to the slurry containing basic zirconium sulfate. Next, 500 g of 25% sodium hydroxide (alkali for neutralization) was added over 60 minutes to form a hydroxide precipitate.

[0192] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

[0193] The obtained hydroxide was dried at 105°C for 24 hours. The dried hydroxide was heat-treated in air at 600°C for 5 hours to obtain a zirconia-based porous material according to Comparative Example 9.

[0194] [Measurement of pore distribution based on mercury intrusion method] For the zirconia-based porous materials of the examples and comparative examples, the pore distribution was obtained using a pore distribution analyzer ("Autopore IV9500," manufactured by Micromeritix) and the mercury intrusion method. The measurement conditions were as follows. <Measurement conditions> Measurement device: Pore size distribution analyzer (Micromeritix Autopore IV9500) Measurement range: 0.0036~10.3μm Number of measurement points: 120 points Mercury contact angle: 140degrees Mercury surface tension: 480dyne / cm

[0195] Using the obtained pore distribution, the maximum value of the peak (dV / dlogD peak) in the range of 10 nm to less than 300 nm, and the pore volume in the range of 300 nm to 100,000 nm were determined. The results are shown in Tables 1 and 2. In the table, "single" means that there is only one peak in the pore distribution range of 10 nm to less than 300 nm based on the mercury intrusion method, and "bimodal" means that there are two or more peaks in the aforementioned range. In the case of "bimodal," the table lists the maximum value of the peak with the larger value among the two peaks.

[0196] The pore distribution of the zirconia-based porous materials obtained for Examples 1 to 3 and Comparative Examples 1 to 3 is shown in Figures 1 to 6.

[0197] [Hardness measurement] The zirconia-based porous materials (powder) of the examples and comparative examples were embedded in epoxy resin, cross-sectionally processed, and prepared as evaluation samples. Hardness was evaluated using a Nano Indenter manufactured by KLA Tencor. Evaluation was performed using a diamond Berkovich-type indenter at an indentation depth of 50 nm. Measurements were performed according to the method compliant with ISO 14577. The results are shown in Tables 1 and 2.

[0198] [Measurement of pore distribution based on the BJH method (before crushing)] For the zirconia-based porous materials of the examples and comparative examples, the pore distribution was obtained using the BJH method with the pore distribution analyzer "Belsorp mini II (manufactured by MicrotracBEL)". The measurement conditions were as follows. <Measurement conditions> Measurement device: Pore size distribution analyzer (Belsorp mini II, manufactured by MicrotracBEL) Measurement range: 2~200nm Number of measurement points: 30 points Analysis method: BJH method

[0199] Using the obtained pore distribution, the pore volume (pore volume B) in the range of 10 nm to 200 nm was determined. The results are shown in Tables 1 and 2.

[0200] [Measurement of pore distribution based on the BJH method after crushing] The zirconia-based porous materials of the examples and comparative examples were subjected to crushing treatment under the following crushing conditions. <Crushing process conditions> 30g of zirconia-based porous material and 300ml of pure water are placed in a 500ml beaker, and the mixture is dispersed for 5 minutes using an ultrasonic homogenizer "Sonifier SFX550" (Emerson Japan Co., Ltd.) at 550W and 37% amplitude. After that, it is dried at 110°C for 24 hours.

[0201] Subsequently, the pore distribution was obtained using the BJH method with the pore distribution analyzer "Belsorp mini II (manufactured by MicrotracBEL)". The measurement conditions were the same as those for measuring the pore distribution using the BJH method before the crushing treatment.

[0202] Using the obtained pore size distribution, the pore volume (pore volume A) in the range of 10 nm or more and 200 nm or less was determined. The results are shown in Tables 1 and 2. In addition, Tables 1 and 2 also show the retention rate X of the pore volume. The retention rate X of the pore volume was obtained by the following formula. <Retention rate X of pore volume> [(Pore volume A) / (Pore volume B)]

[0203] For Examples 1 to 6 and Comparative Examples 1 and 3, the pore size distributions (before and after crushing treatment) of the obtained zirconia-based porous bodies are shown in FIGS. 7 to 14.

[0204] [Measurement of specific surface area (specific surface area B-3) before crushing treatment and before heat treatment] The specific surface areas of the zirconia-based porous bodies of the examples and comparative examples were measured by the BET method using a specific surface area meter (manufactured by Macsorb, Mountech). The results are shown in Tables 1 and 2.

[0205] [Measurement of specific surface area (specific surface area B-2) before crushing treatment and after heat treatment at 1000 °C for 3 hours]<0​​​​​​​​​​[Measurement of specific surface area (specific surface area A-3) after crushing and before heat treatment] The zirconia-based porous materials of the examples and comparative examples were subjected to crushing treatment under the following crushing conditions. <Crushing process conditions> 30g of zirconia-based porous material and 300ml of pure water are placed in a 500ml beaker, and the mixture is dispersed for 5 minutes using an ultrasonic homogenizer "Sonifier SFX550" (Emerson Japan Co., Ltd.) at 550W and 37% amplitude. After that, it is dried at 110°C for 24 hours.

[0208] Subsequently, the specific surface area was measured using the BET method with a surface area meter ("Maxsorb," manufactured by Mountec). The results are shown in Tables 1 and 2.

[0209] [Measurement of specific surface area (specific surface area A-2) after crushing and heat treatment at 1000°C for 3 hours] The zirconia-based porous materials of the examples and comparative examples were subjected to crushing treatment under the following crushing conditions. <Crushing process conditions> 30g of zirconia-based porous material and 300ml of pure water are placed in a 500ml beaker, and the mixture is dispersed for 5 minutes using an ultrasonic homogenizer "Sonifier SFX550" (Emerson Japan Co., Ltd.) at 550W and 37% amplitude. After that, it is dried at 110°C for 24 hours.

[0210] Next, the material was heat-treated at 1000°C for 3 hours under atmospheric pressure (0.1013 MPa) and in an air atmosphere. The specific surface area of ​​the zirconia-based porous material after heat treatment at 1000°C for 3 hours was measured using the BET method with a specific surface area meter ("Macsorb," manufactured by Mountec). The results are shown in Tables 1 and 2.

[0211] [Measurement of specific surface area (specific surface area A) after crushing and heat treatment at 1100°C for 3 hours] The zirconia-based porous materials of the examples and comparative examples were subjected to crushing treatment under the following crushing conditions. <Crushing process conditions> 30g of zirconia-based porous material and 300ml of pure water are placed in a 500ml beaker, and the mixture is dispersed for 5 minutes using an ultrasonic homogenizer "Sonifier SFX550" (Emerson Japan Co., Ltd.) at 550W and 37% amplitude. After that, it is dried at 110°C for 24 hours.

[0212] Next, the material was heat-treated at 1100°C for 3 hours under atmospheric pressure (0.1013 MPa) and in an air atmosphere. The specific surface area of ​​the zirconia-based porous material after heat treatment at 1100°C for 3 hours was measured using the BET method with a specific surface area meter ("Macsorb," manufactured by Mountec). The results are shown in Tables 1 and 2.

[0213] Tables 1 and 2 also show the specific surface area maintenance rates Y, Y-2, and Y-3. The specific surface area maintenance rates Y, Y-2, and Y-3 were obtained using the following formulas. <Maintenance ratio of specific surface area Y> [(Specific surface area A) / (Specific surface area B)] <Maintenance ratio of specific surface area Y-2> [(Specific surface area A-2) / (Specific surface area B-2)] <Maintenance ratio of specific surface area Y-3> [(Specific surface area A-3) / (Specific surface area B-3)]

[0214] [Particle size D 50 Measurement (before crushing)] 0.15 g of the zirconia-based porous material (powder) from the Examples and Comparative Examples, along with 40 ml of a 0.2% sodium hexametaphosphate aqueous solution, were placed in a 50 ml beaker. After dispersing in an ultrasonic cleaner "VS-100 III" (Velvo-Clear Co., Ltd.) at a frequency of 28 kHz for 5 minutes, the mixture was placed in a laser diffraction particle size distribution analyzer ("SALD-2300" manufactured by Shimadzu Corporation) for measurement. The results are shown in Tables 1 and 2.

[0215] [Particle size D after crushing treatment] 50 [Measurement] The zirconia-based porous materials of the examples and comparative examples were subjected to crushing treatment under the following crushing conditions. <Crushing process conditions> 30g of zirconia-based porous material and 300ml of pure water are placed in a 500ml beaker, and the mixture is dispersed for 5 minutes using an ultrasonic homogenizer "Sonicifier SFX550" (Emerson Japan Co., Ltd.) at 550W and 37% amplitude.

[0216] Next, the samples were placed in a laser diffraction particle size distribution analyzer ("SALD-2300," manufactured by Shimadzu Corporation) and measured. The results are shown in Tables 1 and 2.

[0217] [Table 1]

[0218] [Table 2]

Claims

1. 40% or more by mass of zirconia, Oxides of rare earth elements in an amount of 5% to 60% by mass and Includes, A zirconia-based porous material characterized by satisfying all of the following conditions (1) to (2) in its pore size distribution based on the mercury intrusion method. (1) The maximum value of the peak in the range of 10 nm to less than 300 nm is 1.0 ml / g or more and 4.0 ml / g or less. (2) The pore volume between 300 nm and 100,000 nm is 1.00 ml / g or less.

2. The zirconia-based porous material according to claim 1, characterized in that, in the pore size distribution based on the mercury intrusion method, the number of peaks in the range of 10 nm to less than 300 nm is one.

3. When the pore volume in the range of 10 nm to 200 nm in the pore distribution based on the BJH method after crushing treatment under the following crushing treatment conditions is defined as pore volume A, and the pore volume in the range of 10 nm to 200 nm in the pore distribution based on the BJH method before the crushing treatment is defined as pore volume B, The pore volume A is 0.2 ml / g or more and 1.2 ml / g or less. The zirconia-based porous material according to claim 1 or 2, characterized in that the pore volume retention rate X, represented by the following formula (4), is 0.80 or more and 1.10 or less. <Crushing Processing Conditions> Place 30 g of zirconia-based porous material and 300 ml of pure water into a 500 ml beaker and disperse using an ultrasonic homogenizer for 5 minutes. Then, dry at 110°C for 24 hours. <Pore volume maintenance rate X> [(Pore volume A) / (Pore volume B)] Equation (4)

4. When the specific surface area after crushing under the following crushing conditions, and after heat treatment at 1100°C for 3 hours under atmospheric pressure and an air atmosphere, is defined as specific surface area A, and the specific surface area before the crushing treatment, and after heat treatment at 1100°C for 3 hours under atmospheric pressure and an air atmosphere, is defined as specific surface area B, The aforementioned specific surface area A is 15 m ２ / g or more 60m ２ / g or less, The zirconia-based porous material according to claim 1 or 2, characterized in that the maintenance ratio Y of the specific surface area, represented by the following formula (5), is 0.85 or more and 1.05 or less. <Crushing Processing Conditions> Place 30 g of zirconia-based porous material and 300 ml of pure water into a 500 ml beaker and disperse using an ultrasonic homogenizer for 5 minutes. Then, dry at 110°C for 24 hours. <Maintenance ratio of specific surface area Y> [(Specific surface area A) / (specific surface area B)] Formula (5)

5. The specific surface area after heat treatment at 1000°C for 3 hours under atmospheric pressure and in an air atmosphere is 20 m². ２ / g or more 80m ２ The zirconia-based porous material according to claim 1 or 2, characterized in that it is less than or equal to / g.

6. The specific surface area before heat treatment was 30 m². ２ / g or more 120m ２ The zirconia-based porous material according to claim 1 or 2, characterized in that it is less than or equal to / g.

7. Step 1 involves simultaneously adding a zirconium salt solution and a sulfate chlorine agent to heated water to obtain a basic zirconium sulfate-containing slurry. Step 2 involves removing unreacted zirconium salts and soluble zirconium salts, Step 3 involves adding a rare earth salt solution to the basic zirconium sulfate-containing slurry obtained in step 2, and then adding an alkali to obtain a zirconium-containing hydroxide. Step 4 involves heat-treating the zirconium-containing hydroxide obtained in step 3 to obtain a zirconia-based porous body. A method for producing a zirconia-based porous body according to claim 1 or 2, characterized by including the following:

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