Zirconia-based porous body and method for producing zirconia-based porous body

Abstract

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. 【Solution means】 A zirconia-based porous body containing 40 mass% or more of zirconia and 5 mass% or more and 60 mass% or less of an oxide of a rare earth element, and satisfying all of the following (1) to (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 or more and 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 or more and 100,000 nm or less 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] Regarding a zirconia-based porous body used as a catalyst carrier for exhaust gas purification, in order to keep a noble metal catalyst in a highly dispersed state even after being exposed to high temperature for a long time, control of the pore diameter has been studied.

[0003] In Patent Document 1, in the pore size distribution based on the BJH method, when the pore diameter has a peak at 20 to 100 nm, 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, the pore diameter has a peak at 20 to 100 nm, the P / W ratio is 0.03 or more, and it has 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, a zirconia-based porous body having peaks in the pore diameter of 8 to 20 nm and 30 to 100 nm and a total pore volume of 0.4 cc / g or more in the pore size distribution based on the BJH method, and a zirconia-based porous body having a peak in the pore diameter of 20 to 110 nm and a total pore volume of 0.4 cc / g or more in the pore size distribution based on the BJH method are disclosed (see particularly Claim 1).

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

[0006] Patent Document 4 discloses a porous zirconia-based composite oxide characterized in that in the pore size distribution based on the BJH method in the range of 2 nm or more and 200 nm or less, all of the following (1) to (3) are satisfied, and the pore volume in the range of more than 100 nm and 1000 nm or less in the pore size distribution based on the mercury intrusion method is 0.01 cm 3 / g or more and 0.25 cm 3 / g or less. (1) The dV / dlogD peak is in the range of 2 nm or more and 100 nm or less. (2) The maximum value of the dV / dlogD peak is 1.5 or more and 5.0 or less. (3) The pore volume in the range of 2 nm or more and 100 nm or less is 0.30 cm 3 / g or more and 1.50 cm 3 / g or less. A zirconia-based porous body is disclosed.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0008] In Patent Documents 1 to 4, an attempt is made to suppress a decrease in specific surface area after exposure to high temperature by controlling the pore structure of the zirconia-based porous body.

[0009] Here, the zirconia-based porous body is slurried, the particle size is adjusted by wet grinding, and then it is coated on a honeycomb and used. Also, the zirconia-based porous body may be stirred for a long time after being slurried and before being coated.

[0010] However, due to the collapse of the particle aggregation state and the change in the pore structure during the wet grinding or long-time stirring in the catalyst preparation, there are problems such as a decrease in the specific surface area when exposed to high temperatures and a decrease in the catalyst performance.

[0011] The present invention has been made in view of the above-described problems, and an object thereof is to provide a zirconia-based porous body in which the change in the pore size distribution due to the crushing treatment is small and the decrease in the specific surface area due to heating is suppressed. Another object is to provide a method for manufacturing the zirconia-based porous body.

Means for Solving the Problems

[0012] The present invention provides the following. [1] Zirconia of 40% by mass or more, an oxide of a rare earth element of 5% by mass or more and 60% by mass or less, and including, a zirconia-based porous body characterized by satisfying all of the following (1) to (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 or more and 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 or more and 100,000 nm or less is 0.05 ml / g or more and 1.00 ml / g or less.

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

[0014] In the zirconia-based porous body, loosening starts from pores and voids, resulting in a change in the pore size distribution and a decrease in the specific surface area. The inventors have found that pores with a pore diameter of 300 nm or more, whether present or not, do not significantly reduce the specific surface area upon heating. Then, the pore volume in the region of the pore size distribution with a pore diameter of 300 nm or more was reduced. Specifically, the pore volume in the range of 300 nm or more and 100,000 nm or less was set to 1.00 ml / g or less. Since it has a structure without 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 by crushing treatment. Since the change in the pore distribution is small before and after the crushing treatment, it is possible to suppress the decrease in the specific surface area when exposed to high temperature even after the crushing treatment.

[0015] Note that Patent Documents 1-4 do not disclose that the pore volume in the range of 300 nm or more and 100,000 nm or less is 1.00 ml / g or less. Also, with the manufacturing methods of Patent Documents 1-4, it is not possible to make the pore volume in the range of 300 nm or more and 100,000 nm or less 1.00 ml / g or less.

[0016] Further, according to the above configuration, since it contains an oxide of a rare earth element in the range of 5% by mass or more and 60% by mass or less, it is possible to suppress the decrease in the specific surface area when exposed to high temperature, whether before or after the crushing treatment.

[0017] From the above, according to the configuration of [1] above, it is possible to provide a zirconia-based porous body in which the change in the pore size distribution due to the crushing treatment is small and the decrease in the specific surface area due to heating is suppressed.

[0018] Furthermore, the present invention provides the following. [2] The zirconia-based porous body according to [1] above, wherein in the pore size distribution based on the mercury intrusion method, the number of peaks present in the range of 10 nm or more and less than 300 nm is one.

[0019] When the number of peaks present in the range of 10 nm or more and less than 300 nm in the pore size distribution based on the mercury intrusion method is one, the zirconia-based porous body becomes harder and the pore distribution is less likely to change by the crushing treatment.

[0020] Furthermore, the present invention provides the following. [3] 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 0.2 ml / g or more and 1.2 ml / g or less, the zirconia-based porous body according to the above [1] or [2], characterized in 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. <Maintenance rate X of pore volume> [(Pore volume A) / (Pore volume B)] Formula (4)

[0021] When the maintenance rate of the pore volume in the range of 10 nm or more and 200 nm or less before and after the crushing treatment (the maintenance rate X of the pore volume) is 0.80 or more and 1.10 or less, it can be said that the pore volume does not change significantly even after the crushing treatment. Also, when 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 described above, since the pore volume in the range of 300 nm or more and 100,000 nm or less is 1.00 ml / g or less and there are almost no pores in the range of 300 nm or more, the pore volume in the range of 300 nm or more and 100,000 nm or less does not change.

[0022] Furthermore, the present invention provides the following. [4] When the specific surface area after heat treatment at 1100 °C for 3 hours in an air atmosphere at atmospheric pressure after the crushing treatment under the following crushing treatment conditions is defined as specific surface area A, and the specific surface area after heat treatment at 1100 °C for 3 hours in an air atmosphere at atmospheric pressure before the crushing treatment is defined as specific surface area B, the specific surface area A is 15 m 2 / g or more and 60 m2 is less than / 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. Further, 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 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, and the zirconia-based porous body according to any one of the above [1] to [4].

[0025] 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, and 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 is 30 m 2 / g or more and 120 m 2 / g or less, it can be said that the specific surface area before heat treatment is sufficiently large. When the specific surface area before heat treatment is large, it is easy to increase the specific surface area after heat treatment.

[0028] Furthermore, the present invention provides the following. [7] Step 1 of obtaining a basic zirconium sulfate-containing slurry by simultaneously adding a zirconium salt solution and a sulfate chlorinating agent to heated water; Step 2 of removing unreacted zirconium salt and soluble zirconium salt; Step 3 of 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 of obtaining a zirconia-based porous body by heat-treating the zirconium-containing hydroxide obtained in Step 3 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, a zirconium salt solution and a sulfate chlorinating agent are simultaneously added to heated water, and by uniformly performing sulfate chlorination, the pore size distribution of basic zirconium sulfate can be controlled to satisfy the above (1) to (2). That is, it is possible to form only specific pores important for suppressing the decrease in specific surface area due to heating. During the crushing process, particles are loosened starting from pores, particularly macropores of 300 nm or more, so that particles having no unnecessary pores are formed, and it becomes difficult to crush the particles.

[0030] Also, according to the above configuration, in Step 2, by removing unreacted zirconium salt and soluble zirconium salt, it is possible to prevent the generation of fine particles during neutralization and the generation of coarse particles due to aggregation of secondary particles. As a result, it is possible to obtain a zirconia-based porous body that is difficult to loosen and has a small change in pore size distribution due to the crushing process.

Effect of the Invention

[0031] According to the present invention, it is possible to provide a zirconia-based porous body in which the change in pore size distribution due to the crushing treatment is small and the decrease in specific surface area due to heating is suppressed. Further, it is possible to provide a method for producing the zirconia-based porous body.

Brief Description of the Drawings

[0032]

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Embodiments for Carrying Out the Invention

[0033] Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited only to these embodiments. In this specification, the zirconia-based porous body contains an impurity metal compound of 10 mass% or less including hafnium. Further, in this specification, the expressions "contain" and "include" include the concepts of "contain", "include", "consisting essentially of", and "consisting only of".

[0034] The maximum value and the minimum value of the content of each component shown below are the preferable minimum value and the preferable maximum value of the present invention independently of the content of other components. Also, the maximum value and the minimum value of various parameters (measurement values, etc.) shown below are the preferable minimum value and the preferable maximum value of the present invention independently of the content (composition) of each component.

[0035] [Zirconia-based Porous Body] The zirconia-based porous body according to the present embodiment contains zirconia and an oxide of a rare earth element, although details will be described later. The use of the zirconia-based porous body according to the present embodiment is not particularly limited, but it is useful as a catalyst carrier for exhaust gas purification. When used as a catalyst carrier for exhaust gas purification, examples of the catalyst that can be supported include noble metal catalysts.

[0036] [Pore Size Distribution Based on Mercury Intrusion Method] The zirconia-based porous body according to the present embodiment satisfies all of the following (1) to (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 or more and 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 or more and 100000 nm or less is 0.05 ml / g or more and 1.00 ml / g or less.

[0037] According to the zirconia-based porous body, in the pore size distribution based on the mercury intrusion method, since the maximum value of the peak in the range of 10 nm or more and less than 300 nm is 1.0 ml / g or more and 4.0 ml / g or less, it is possible to suppress a decrease in the specific surface area when exposed to a high temperature (particularly, 1100°C). Note that the peak refers to the peak of dV / dlogD.

[0038] In the pore size distribution based on the mercury intrusion method, the number of peaks present in the range of 10 nm or more and less than 300 nm may be one or may be plural (for example, two (bimodal)), but it is preferably one. When the number of the peaks is one, the zirconia-based porous body becomes harder and the pore distribution becomes less likely to change by the crushing treatment. The "maximum value of the peak in the range of 10 nm or more and less than 300 nm" refers to the peak (the value of dV / dlogD) when there is one peak in the range of 10 nm or more and less than 300 nm. Further, when there are plural peaks in the range of 10 nm or more and less than 300 nm, the "maximum value of the peak in the range of 10 nm or more and less than 300 nm" refers to the one with the largest peak value (the value of dV / dlogD) among the plural peaks. Note that when there are two or more peaks satisfying 1.0 ml / g or more and 4.0 ml / g or less in the range of 10 nm or more and less than 300 nm, if the maximum value of the peak with the largest value satisfies 1.0 ml / g or more and 4.0 ml / g or less, whether the maximum values of the other peaks satisfy 1.0 ml / g or more and 4.0 ml / g or less or not, it satisfies "the maximum value of the peak in the range of 10 nm or more and less than 300 nm is 1.0 ml / g or more and 4.0 ml / g or less."

[0039] The maximum value of the peak is preferably 1.2 ml / g or more, more preferably 1.4 ml / g or more. The maximum value of the peak is preferably 3.8 ml / g or less, more preferably 3.6 ml / g or less. The maximum value of the 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] Further, according to the zirconia-based porous body, in the pore size distribution based on the mercury intrusion method, the pore volume of 300 nm or more and 100,000 nm or less is 0.05 ml / g or more and 1.00 ml / g or less. Since it has a structure without 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 by the crushing treatment. Since the change in the pore distribution is small before and after the crushing treatment, it is possible to suppress the decrease in the specific surface area when exposed to a high temperature even after the crushing treatment.

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

[0042] In the zirconia-based porous body, in the pore size distribution based on the mercury intrusion method, the maximum value of the peak in the range of 300 nm or more and 100,000 nm or less 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 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 the pore distribution based on the mercury intrusion method are according to the method described 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 conforming to 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 even more preferably 0.54 GPa or more. The higher the hardness, the more preferable it is. 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 even 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, "Sonifier SFX550" (Nippon Emason Co., Ltd.) is used as the ultrasonic homogenizer, and dispersion is performed at 550 W and an amplitude of 37%. <Maintenance rate X of pore volume> [(Pore volume A) / (Pore volume B)] Formula (4)

[0048] When the retention rate of the pore volume in the range of 10 nm or more and 200 nm or less before and after the crushing treatment (the retention rate X of the pore volume) is 0.80 or more and 1.10 or less, it can be said that the pore volume does not change significantly even after the crushing treatment. Also, when 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 retention rate X of the pore volume is more preferably 0.82 or more, and even more preferably 0.84 or more. The retention rate X of the pore volume is preferably as large as possible. For example, it is 1.08 or less, 1.06 or less, etc. The retention rate X of the pore volume 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. For example, it is 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. For example, it is 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 the pore distribution based on the BJH method are according to the method described in the examples.

[0053] <Retention rate of specific surface area after heat treatment at 1100°C for 3 hours before and after crushing treatment> The specific surface area of the zirconia-based porous body after being crushed under the following crushing treatment conditions and then heat-treated at 1100°C for 3 hours under atmospheric pressure and in an air atmosphere is defined as specific surface area A, and the specific surface area of the zirconia-based porous body before being crushed and then heat-treated at 1100°C for 3 hours under atmospheric pressure and in an air atmosphere is defined as specific surface area B. When the specific surface area A is 15 m 2 / g or more and 60 m 2 / g or less, and it is preferable 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 them with an ultrasonic homogenizer for 5 minutes. Then, dry them 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 Y of specific surface area> [(Specific surface area A) / (Specific surface area B)] Formula (5)

[0054] 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 after the crushing treatment. 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 then heat-treated at 1100°C for 3 hours is sufficiently large.

[0055] The maintenance rate Y of the specific surface area is more preferably 0.87 or more, and even more preferably 0.89 or more. The maintenance rate Y of the specific surface area is preferably as large as possible. For example, it is 1.03 or less, 1.01 or less, etc. The maintenance rate 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 m 2 / g or more, and even more preferably 16 m2 is 1 / g or more. The specific surface area A is preferably as large as possible. For example, it is 58 m 2 / g or less, 56 m 2 / g or less, etc. The specific surface area A is more preferably 15 m 2 / g or more and 58 m 2 / g or less, and even more preferably 16 m 2 / g or more and 56 m 2 / g or less.

[0057] The specific surface area B is more preferably 16 m 2 / g or more, and even more preferably 17 m 2 / g or more. The specific surface area B is preferably as large as possible. For example, it is 58 m 2 / g or less, 56 m 2 / g or less, etc. The specific surface area B is more preferably 16 m 2 / g or more and 58 m 2 / g or less, and even more preferably 17 m 2 / g or more and 56 m 2 / g or less.

[0058] <Retention rate of specific surface area after heat treatment at 1000 °C for 3 hours before and after crushing treatment> For the zirconia-based porous body, when the specific surface area after heat treatment at 1000 °C for 3 hours under atmospheric pressure and in an air atmosphere after crushing treatment under the following crushing treatment conditions is defined as specific surface area A-2, and the specific surface area after heat treatment at 1000 °C for 3 hours under atmospheric pressure and in an air atmosphere before the crushing treatment is defined as specific surface area B-2, it is preferable that the retention rate Y-2 of the specific surface area represented by the following formula (6) 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 them with an ultrasonic homogenizer for 5 minutes. Then, dry at 110 °C for 24 hours. The dispersion by the ultrasonic homogenizer is carried out 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%. <Retention rate Y-2 of specific surface area> [(Specific surface area A-2) / (Specific surface area B-2)] Formula (6)

[0059] When the retention rate Y-2 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 after the crushing treatment.

[0060] The retention rate Y-2 of the specific surface area is more preferably 0.87 or more, and even more preferably 0.89 or more. The retention rate Y-2 of the specific surface area is preferably as large as possible, but for example, it is 1.03 or less, 1.01 or less, etc. The retention rate 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 m 2 / g or more, and even more preferably 24 m 2 / g or more. The specific surface area A-2 is preferably as large as possible, but for example, it is 78 m 2 / g or less, 76 m 2 / g or less, etc. The specific surface area A-2 is more preferably 22 m 2 / g or more and 78 m 2 / g or less, and even more preferably 24 m 2 / g or more and 76 m 2 / g or less. When the specific surface area A-2 is 22 m 2 / g or more, it can be said that the specific surface area after the crushing treatment and after heat treatment at 1000 °C for 3 hours is sufficiently large.

[0062] The specific surface area B-2 is more preferably 22 m 2 / g or more, still more preferably 24 m 2 / g or more. The larger the specific surface area B-2, the more preferable. For example, it is 78 m 2 / g or less, 76 m 2 / g or less, etc. The specific surface area B-2 is more preferably 22 m 2 / g or more and 78 m 2 / g or less, still more preferably 24 m 2 / g or more and 76 m 2 / g or less. When the specific surface area B-2 is 22 m 2 / g or more, it can be said that the specific surface area before the crushing treatment and after heat treatment at 1000 °C for 3 hours is sufficiently large.

[0063] <Retention rate of specific surface area before heat treatment before and after crushing treatment> When the specific surface area (before heat treatment) after the crushing treatment of the zirconia-based porous body under the following crushing treatment conditions is defined as the specific surface area A-3, and the specific surface area (before heat treatment) before the crushing treatment is defined as the specific surface area B-3, it is preferable that the retention rate Y-3 of the specific surface area represented by the following formula (7) 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 them with an ultrasonic homogenizer for 5 minutes. 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%. <Retention rate Y-3 of specific surface area> [(Specific surface area A-3) / (Specific surface area B-3)] Formula (7)

[0064] When the retention rate Y-3 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 after the crushing treatment.

[0065] The maintenance rate Y-3 of the specific surface area is more preferably 0.87 or more, and even more preferably 0.89 or more. The maintenance rate Y-3 of the specific surface area is preferably as large as possible. For example, it is 1.03 or less, 1.01 or less, etc. The maintenance rate 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 m 2 / g or more, and even more preferably 34 m 2 / g or more. The specific surface area A-3 is preferably as large as possible. For example, it is 118 m 2 / g or less, 116 m 2 / g or less, etc. The specific surface area A-3 is more preferably 32 m 2 / g or more and 118 m 2 / g or less, and even more preferably 34 m 2 / g or more and 116 m 2 / g or less. When the specific surface area A-3 is 32 m 2 / g or more, it can be said that the specific surface area after the crushing treatment is sufficiently large.

[0067] The specific surface area B-3 is more preferably 32 m 2 / g or more, and even more preferably 34 m 2 / g or more. The specific surface area B-3 is preferably as large as possible. For example, it is 118 m 2 / g or less, 116 m 2 / g or less, etc. The specific surface area B-3 is more preferably 32 m 2 / g or more and 118 m 2 / g or less, and even more preferably 34 m 2 / g or more and 116 m 2 / g or less. When the specific surface area B-3 is 32 m 2 / g or more, it can be said that the specific surface area before the crushing treatment and before the heat treatment is sufficiently large.

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

[0069] <Particle diameter D after crushing treatment 50 > The particle diameter D of the zirconia-based porous body after the crushing treatment under the following crushing treatment conditions 50 is preferably 1.0 μm or more and 50.0 μm 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. The dispersion by the ultrasonic homogenizer is performed at 550 W and an amplitude of 37%. More specifically, "Sonifier SFX550" (Nippon Emason Co., Ltd.) is used as the ultrasonic homogenizer and dispersed at 550 W and an amplitude of 37%. The particle diameter D after the crushing treatment 50 If it is 1.0 μm or more and 50.0 μm or less, it can be suitably coated on the honeycomb after the pulverization treatment.

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

[0071] <Particle diameter D before crushing treatment 50 > The particle diameter D of the zirconia-based porous body before the crushing treatment 50 is preferably 1.2 μm or more and 49.8 μm or less. The particle diameter D before the crushing treatment 50 If it is 1.2 μm or more and 49.8 μm or less, it can be suitably coated on the honeycomb after the pulverization treatment.

[0072] The particle diameter D before the crushing treatment 50 is more preferably 1.2 μm or more, still more preferably 1.4 μm or more. The particle diameter D before the crushing treatment 50 is more preferably 49.8 μm or less, still more preferably 49.6 μm or less. The particle diameter D before the crushing treatment 50 is more preferably 1.2 μm or more and 49.8 μm or less, still more preferably 1.4 μm or more and 49.6 μm or less.

[0073] Details of the measurement method of the particle diameter D 50 are according to the method described in the examples.

[0074] <Composition> The zirconia-based porous body contains zirconia. When the total amount of the zirconia-based porous body is 100% by mass, the content of the zirconia is 40% by mass or more. Since the content of the zirconia is 40% by mass or more, it can be suitably used as a catalyst carrier.

[0075] When the total amount of the zirconia-based porous body is 100% by mass, the content of the zirconia is preferably 40% by mass or more, more preferably 45% by mass or more, still more preferably 50% by mass or more. The upper limit value of the content of the zirconia is not particularly limited, but the content of the zirconia is preferably 99% by mass or less, more preferably 98% by mass or less.

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

[0077] When the total amount of the zirconia-based porous body is 100% by mass, the content of the oxide of the rare earth element is 5% by mass or more and 60% by mass or less. Since the oxide of the rare earth element is contained in the range of 5% by mass or more and 60% by mass or less, it is possible to suppress the decrease in the specific surface area when exposed to high temperature, either before or after the crushing treatment.

[0078] When the total amount of the zirconia-based porous body is 100% by mass, the content of the rare earth element oxide is preferably 6% by mass or more, more preferably 7% by mass or more, still more preferably 10% by mass or more, particularly preferably 15% by mass or more, and especially preferably 20% by mass or more. When the total amount of the zirconia-based porous body is 100% by mass, the content of the rare earth element oxide is preferably 59% by mass or less, more preferably 58% by mass or less, still more preferably 55% by mass or less, particularly preferably 50% by mass or less. When the total amount of the zirconia-based porous body is 100% by mass, the content of the rare earth element oxide is preferably 6% by mass or more and 59% by mass or less, more preferably 7% by mass or more and 58% by mass or less, still more preferably 10% by mass or more and 55% by mass or less, particularly preferably 15% by mass or more and 55% by mass or less, and especially preferably 20% by mass or more and 55% by mass, 20% by mass or more and 50% by mass.

[0079] The rare earth elements refer to 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 body does not contain Pm. That is, it is more preferable that the zirconia-based porous body contains one or more oxides selected from rare earth elements other than Pm.

[0080] Since it contains one or more oxides selected from rare earth elements, the decrease in specific surface area when exposed to high temperature can be suppressed in any case before or after the crushing treatment.

[0081] Among the rare earth elements, Y (yttrium), La (lanthanum), Ce (cerium), Nd (neodymium), and Pr (praseodymium) are preferable. That is, it is preferable that the zirconia-based porous body contains one or more oxides selected from the group consisting of lanthanum oxide, cerium oxide, neodymium oxide, praseodymium oxide, and yttrium oxide.

[0082] In addition to zirconia and the oxides of the rare earth elements, the zirconia-based porous body 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 may contain oxides of one or more elements selected from the group consisting of. Hereinafter, the elements shown in A) to D) are referred to as "other elements" in this specification. When the zirconia-based porous body contains oxides of the other elements, the content of the oxides of the other elements can be 0.1% by mass or more in terms of oxide when the total of the zirconia-based porous body is 100% by mass. The content of the oxides of the other elements has no particular upper limit, but can 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 metal include Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, Ta, W, Ag, etc. Examples of the alkaline earth metal include Mg, Ca, Sr, Ba, etc. Examples of the platinum group in the previous period include Rh, Pd, Pt, Ir, etc.

[0083] In the zirconia-based porous body, the total content of zirconia and rare earth oxide is preferably 80% by mass or more and 100% by mass or less. The total content of zirconia and rare earth oxide is more preferably 85% by mass or more, and still more preferably 90% by mass or more. The total content of zirconia and rare earth oxide is more preferably 99% by mass or less, and still more preferably 98% by mass or less.

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

[0085] [Method for producing a zirconia-based porous body] Hereinafter, an example of a method for producing a zirconia-based porous body will be described. However, the method for producing a zirconia-based porous body of the present invention is not limited to the following examples.

[0086] The method for producing a zirconia-based porous body according to this embodiment is Step 1 of obtaining a basic zirconium sulfate-containing slurry by simultaneously adding a zirconium salt solution and a sulfate chlorinating agent to heated water, Step 2 of removing unreacted zirconium salt and soluble zirconium salt, Step 3 of 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 of obtaining a zirconia-based porous body by heat-treating the zirconium-containing hydroxide obtained in Step 3.

[0087] <Step 1> In the method for producing a zirconia-based porous body according to this embodiment, first, a basic zirconium sulfate-containing slurry is obtained by simultaneously adding a zirconium salt solution and a sulfate chlorinating agent to heated water.

[0088] By simultaneously adding a zirconium salt solution and a sulfate chlorinating agent to heated water and uniformly performing sulfate chlorination, the pore size distribution of basic zirconium sulfate can be controlled to satisfy the above (1) to the above (2), and only specific pores important for suppressing the decrease in specific surface area due to heating can be formed. During the crushing process, since the particles are loosened starting from pores, particularly macropores of 300 nm or more, the particles having no unnecessary pores are difficult to be crushed.

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

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

[0091] The zirconium salt may be any one that supplies zirconium ions. For example, zirconium oxynitrate, zirconium oxychloride, zirconium nitrate, hydrates thereof, etc. can be used. These can be used alone or in combination of two or more.

[0092] The solvent for preparing the zirconium salt solution may be selected according to the type of zirconium salt. Usually, water (pure water, ion-exchanged water) is preferred.

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

[0094] The sulfate-forming agent is not limited as long as it reacts with zirconium ions to form a sulfate (i.e., a reagent for sulfate formation). For example, sodium sulfate, potassium sulfate, ammonium sulfate, etc. are exemplified. The sulfate-forming agent may be in any form such as powder form or solution form, but a solution (especially an aqueous solution) is preferred. The concentration of the solution when using a solution can be set as appropriate.

[0095] The sulfate-forming agent to be added is preferably added so that the weight ratio of sulfate radical (SO4 2- ) / ZrO2 is 0.3 or more and 0.7 or less.

[0096] When simultaneously adding a zirconium salt solution and a sulfate-forming agent to heated water, the addition rate is not particularly limited as long as uniform sulfate oxidation can be achieved. For example, when adding 400 g to 600 g of a zirconyl chloride solution with a ZrO2 concentration of 15% by mass and 300 g to 400 g of 15% sodium sulfate (sulfate-forming agent), it is preferably added over 30 minutes to 90 minutes.

[0097] When simultaneously adding a zirconium salt solution and a sulfate-forming agent to heated water, the temperature of the zirconium salt solution and the sulfate-forming agent is not particularly limited, but is preferably 10°C or more and 90°C or less, and more preferably 20°C or more and 80°C or less.

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

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

[0100] <Step 2> Next, unreacted zirconium salts and soluble zirconium salts are removed. The method for removing unreacted zirconium salts and soluble zirconium salts is not particularly limited, and examples include a method of decantation to remove the supernatant.

[0101] By removing unreacted zirconium salts and soluble zirconium salts, 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. A zirconia-based porous body that is difficult to loosen and has a small change in pore size distribution due to crushing treatment can be obtained.

[0102] <Step 3> Next, a rare earth salt solution is added to the basic zirconium sulfate-containing slurry (basic zirconium sulfate-containing slurry from which unreacted zirconium salts and soluble zirconium salts have been removed) obtained in Step 2. 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. Then, an alkali is added to obtain a zirconium-containing hydroxide.

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

[0104] The addition amount of the alkali is not particularly limited as long as it can generate a zirconium-containing hydroxide (zirconium hydroxide) as a precipitate from the basic zirconium sulfate solution. Usually, it is added so that the pH of the above solution is 11 or more, preferably 12 or more.

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

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

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

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

[0109] The manufacturing method of the zirconia-based porous body according to this embodiment has been described above.

Examples

[0110] Hereinafter, the present invention will be described in detail using examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the zirconia-based porous bodies obtained in the examples and comparative examples, hafnium is contained as an unavoidable impurity in an amount of 1 to 3% by mass based on 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 contents of the respective components shown in the following examples should be considered as the preferable minimum and maximum values of the present invention regardless of the contents of the other components. Also, the maximum and minimum values of the measured values shown in the following examples should be considered as the preferable minimum and maximum values of the present invention regardless of the contents (composition) of the respective components.

[0112] [Preparation of Zirconia-based Porous Body] (Example 1) 188 g of zirconium oxychloride octahydrate (ZrO2 equivalent: 72 g) was dissolved in ion-exchanged water to prepare a zirconium oxychloride solution having a ZrO2 concentration of 15% by mass. To 600 g of ion-exchanged water heated to 90°C, 480 g of the zirconium oxychloride solution heated to 90°C and 360 g of 15% sodium sulfate (sulfate chlorinating agent) heated to 90°C were simultaneously added over 60 minutes, and then held for another 60 minutes to obtain 5 mass% basic zirconium sulfate. Thereafter, it was allowed to cool to room temperature to obtain a basic zirconium sulfate-containing slurry (Step 1).

[0113] The obtained basic zirconium sulfate-containing slurry 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 mass% (Step 2).

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

[0115] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

[0116] 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 1 (Step 4).

[0117] (Example 2) 144 g of zirconium oxychloride octahydrate (ZrO2 equivalent: 55 g) was dissolved in ion-exchanged water to prepare a zirconium oxychloride solution having a ZrO2 concentration of 15 mass%. 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 (sulfating agent) heated to 95°C were simultaneously added over 60 minutes, and the mixture was further held for 60 minutes to obtain 7 mass% basic zirconium sulfate. Thereafter, the mixture was allowed to cool to room temperature to obtain a basic zirconium sulfate-containing slurry (Step 1).

[0118] The obtained basic zirconium sulfate-containing slurry was decanted to remove the supernatant, and unreacted zirconium salts and soluble zirconium salts were removed. Thereafter, ion-exchanged water was added to make the concentration 5 mass% (Step 2).

[0119] Next, 400 g of a cerium nitrate solution (in terms of CeO2: 40 g) and 50 g of a lanthanum nitrate solution (in terms of La2O3: 5 g) were added to the basic zirconium sulfate-containing slurry obtained in Step 2. Next, 500 g of 25% sodium hydroxide (alkali for neutralization) was added over 60 minutes to form a zirconium-containing hydroxide (hydroxide precipitate) (Step 3).

[0120] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

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

[0122] (Example 3) 131 g of zirconium oxychloride octahydrate (in terms of ZrO2: 50 g) was dissolved in ion-exchanged water to prepare a zirconium oxychloride solution having a ZrO2 concentration of 15 mass%. To 450 g of ion-exchanged water heated to 95°C, 360 g of the zirconium oxychloride solution heated to 95°C and 270 g of 15% sodium sulfate (sulfating agent) heated to 95°C were simultaneously added over 60 minutes, and the mixture was further held for 60 minutes to obtain 5 mass% basic zirconium sulfate. Thereafter, the mixture was allowed to cool to room temperature to obtain a basic zirconium sulfate-containing slurry (Step 1).

[0123] The obtained zirconium basic sulfate-containing slurry 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 (Step 2).

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

[0125] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

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

[0127] (Example 4) 162 g of zirconium oxychloride octahydrate (in terms of ZrO2: 62 g) was dissolved in ion-exchanged water to prepare a zirconium oxychloride solution having a ZrO2 concentration of 15% by mass. To 517 g of ion-exchanged water heated to 90°C, 413 g of the zirconium oxychloride solution heated to 90°C and 310 g of 15% sodium sulfate (sulfate chlorinating agent) heated to 90°C were simultaneously added over 30 minutes, and further held for 60 minutes to obtain 5% by mass of zirconium basic sulfate. Thereafter, it was allowed to cool to room temperature to obtain a zirconium basic sulfate-containing slurry. (Step 1).

[0128] The obtained zirconium basic sulfate-containing slurry 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 (Step 2).

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

[0130] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

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

[0132] (Example 5) 118 g of zirconium oxychloride octahydrate (in terms of ZrO₂: 45 g) was dissolved in ion-exchanged water to prepare a zirconium oxychloride solution having a ZrO₂ concentration of 15% by mass. 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 chlorinating agent) heated to 90 °C were simultaneously added over 90 minutes, and then held for 60 minutes to obtain 5% by mass of zirconium basic sulfate. Thereafter, it was allowed to cool to room temperature to obtain a zirconium basic sulfate-containing slurry (Step 1).

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

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

[0135] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

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

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

[0138] The obtained zirconium basic sulfate-containing slurry 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 (Step 2).

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

[0140] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

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

[0142] (Example 7) 209 g of zirconium oxychloride octahydrate (ZrO2 equivalent: 80 g) was dissolved in ion-exchanged water to prepare a zirconium oxychloride solution having a ZrO2 concentration of 15% by mass. 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 chlorinating agent) heated to 90 °C were simultaneously added over 60 minutes, and further held for 60 minutes to obtain 5% by mass of zirconium basic sulfate. Thereafter, it was allowed to cool to room temperature to obtain a zirconium basic sulfate-containing slurry (Step 1).

[0143] The obtained zirconium basic sulfate-containing slurry 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 (Step 2).

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

[0145] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

[0146] 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 Example 7 (Step 4).

[0147] (Example 8) 209 g of zirconium oxychloride octahydrate (in terms of ZrO2: 80 g) was dissolved in ion-exchanged water to prepare a zirconium oxychloride solution having a ZrO2 concentration of 15% by mass. To 210 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 chlorinating agent) heated to 90°C were simultaneously added over 60 minutes, and further held for 60 minutes to obtain 3% by mass of zirconium basic sulfate. Thereafter, it was allowed to cool to room temperature to obtain a zirconium basic sulfate-containing slurry (Step 1).

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

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

[0150] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

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

[0152] (Example 9) 157 g of zirconium oxychloride octahydrate (in terms of ZrO₂: 59.9 g) was dissolved in ion-exchanged water to prepare a zirconium oxychloride solution having a ZrO₂ concentration of 15% by mass. To 500 g of ion-exchanged water heated to 95 °C, 400 g of the zirconium oxychloride solution heated to 95 °C and 300 g of 15% sodium sulfate (sulfate chlorinating agent) heated to 95 °C were simultaneously added over 90 minutes, and further held for 60 minutes to obtain 5 wt% zirconium basic sulfate. Thereafter, it was allowed to cool to room temperature to obtain a zirconium basic sulfate-containing slurry (Step 1).

[0153] The obtained zirconium basic sulfate-containing slurry was decanted to remove the supernatant, and the unreacted zirconium salt and the soluble zirconium salt were removed. Thereafter, ion-exchanged water was added to make it 5% by mass (Step 2).

[0154] Next, 320 g of a cerium nitrate solution (in terms of CeO₂: 32 g), 20 g of a lanthanum nitrate solution (in terms of La₂O₃: 2 g), 20 g of a neodymium nitrate solution (in terms of Nd₂O₃: 2 g), and 20 g of a praseodymium nitrate solution (Pr6O11 Conversion: 2 g of yttrium nitrate solution (2 g in terms of Y2O3) and 1 g of iron nitrate solution (0.1 g in terms of Fe2O3) were added. Next, 500 g of 25% sodium hydroxide (alkali for neutralization) was added over 60 minutes to produce a zirconium-containing hydroxide (hydroxide precipitate) (Step 3).

[0155] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

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

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

[0158] The obtained slurry containing basic zirconium sulfate was decanted to remove the supernatant, removing unreacted zirconium salts and soluble zirconium salts. Thereafter, ion-exchanged water was added to make it 5% by mass (Step 2).

[0159] Next, 120 g of lanthanum nitrate solution (12 g in terms of La2O3) and 250 g of yttrium nitrate solution (25 g in terms of Y2O3) were added to the slurry containing basic zirconium sulfate obtained in Step 2. Next, 500 g of 25% sodium hydroxide (alkali for neutralization) was added over 60 minutes to produce a 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 (in terms of ZrO2: 72 g) was dissolved in ion-exchanged water. Next, the acid concentration was adjusted to 0.67 N and the ZrO2 concentration was adjusted to 4 w / v% with 35% hydrochloric acid and ion-exchanged water. The obtained solution was placed in 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 a cerium nitrate solution (in terms of CeO2: 21 g), 20 g of a lanthanum nitrate solution (in terms of La2O3: 2 g), and 50 g of a neodymium nitrate solution (in terms of Nd2O3: 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 a 25% aqueous sodium sulfate solution and 450 g of an aqueous zirconium oxychloride solution having a ZrO2 conversion of 16% 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 the contact and mixing was held at 95 °C for 4 hours for aging to obtain basic zirconium sulfate. Next, after cooling the aged reaction solution containing basic zirconium sulfate to room temperature, 105 g of an aqueous cerium nitrate solution equivalent to 20% in terms of CeO2, 8.5 g of an aqueous lanthanum nitrate solution (manufactured by Wako Pure Chemical Industries, Ltd.) equivalent to 20% in terms of La2O3, and 26.5 g of an aqueous neodymium nitrate solution equivalent to 20% in terms of Nd2O3 were added and uniformly mixed. Next, a 25% aqueous sodium hydroxide solution was added to the obtained mixed solution, and the solution was neutralized until the pH reached 13 or higher to form a hydroxide precipitate. The obtained hydroxide precipitate was filtered, thoroughly washed with water, and the obtained hydroxide was dried at 105 °C for 24 hours. The dried hydroxide was heat-treated (calcined) at 600 °C in the air for 5 hours to obtain a zirconia-based porous body according to Comparative Example 2.

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

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

[0166] The obtained slurry containing basic zirconium sulfate was decanted to remove the supernatant, removing unreacted zirconium salts and soluble zirconium salts. Thereafter, ion-exchanged water was added to make it 5% by mass.

[0167] Next, 400 g of a cerium nitrate solution (CeO₂ equivalent: 40 g) and 50 g of a neodymium nitrate solution (La₂O₃ 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 to form a hydroxide precipitate.

[0168] Thereafter, the obtained hydroxide precipitate was 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 body according to Comparative Example 4.

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

[0171] The obtained basic zirconium sulfate-containing slurry 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 mass%.

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

[0173] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

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

[0175] (Comparative Example 6) 209 g of zirconium oxychloride octahydrate (ZrO2 equivalent: 80 g) was dissolved in ion-exchanged water to prepare a solution with a ZrO2 concentration of 5 mass%. 400 g of 15% sodium sulfate (sulfate chlorinating agent) was added over 60 minutes, and after the temperature was raised to 90°C, the mixture was held for 60 minutes. Thereafter, the mixture was allowed to cool to room temperature to obtain a basic zirconium sulfate-containing slurry. The obtained basic zirconium sulfate-containing slurry 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 mass%.

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

[0177] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

[0178] 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 6.

[0179] (Comparative Example 7) 162 g of zirconium oxychloride octahydrate (62 g in terms of ZrO₂) was dissolved in ion-exchanged water to prepare a zirconium oxychloride solution having a ZrO₂ concentration of 15% by mass. To 517 g of ion-exchanged water heated to 80 °C, 413 g of the zirconium oxychloride solution heated to 80 °C and 310 g of 15% sodium sulfate (sulfate chlorinating agent) heated to 80 °C were simultaneously added over 60 minutes, and then held for another 60 minutes to obtain 5% by mass of zirconium basic sulfate. Thereafter, it was allowed to cool to room temperature to obtain a zirconium basic sulfate-containing slurry.

[0180] The obtained zirconium basic sulfate-containing slurry was decanted to remove the supernatant, and the unreacted zirconium salt and the soluble zirconium salt were removed. Thereafter, ion-exchanged water was added to make it 5% by mass.

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

[0182] Thereafter, the obtained hydroxide precipitate was filtered and thoroughly washed with water.

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

[0184] (Comparative Example 8) 118 g of zirconium oxychloride octahydrate (ZrO2 equivalent: 45 g) was dissolved in ion-exchanged water to prepare a zirconium oxychloride solution having a ZrO2 concentration of 15% by mass. To 1725 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 chlorinating agent) heated to 90°C were simultaneously added over 90 minutes, and further held for 60 minutes to obtain 2% by mass of zirconium basic sulfate. Thereafter, it was allowed to cool to room temperature to obtain a zirconium basic sulfate-containing slurry.

[0185] The obtained zirconium basic sulfate-containing slurry 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.

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

[0187] Subsequently, 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 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 (in terms of ZrO₂: 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 another 60 minutes to obtain 5% by mass basic zirconium sulfate. Subsequently, it was allowed to cool to room temperature to obtain a basic zirconium sulfate-containing slurry.

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

[0191] Next, 320 g of a cerium nitrate solution (in terms of CeO₂: 32 g), 20 g of a lanthanum nitrate solution (in terms of La₂O₃: 2 g), 20 g of a neodymium nitrate solution (in terms of Nd₂O₃: 2 g), 20 g of a praseodymium nitrate solution (in terms of Pr₆O 11 (in terms of Pr₆O₁₁: 2 g), 20 g of a yttrium nitrate solution (in terms of Y₂O₃: 2 g), and 1 g of an iron nitrate solution (in terms of Fe₂O₃: 0.1 g) were added to the basic zirconium sulfate-containing slurry. Next, 500 g of 25% sodium hydroxide (alkali for neutralization) was added over 60 minutes to form a hydroxide precipitate.

[0192] Subsequently, 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 at 600 °C for 5 hours in the air to obtain a zirconia-based porous body according to Comparative Example 9.

[0194] [Measurement of Pore Distribution Based on Mercury Intrusion Porosimetry] For the zirconia-based porous bodies of the examples and comparative examples, the pore distribution was obtained by mercury intrusion porosimetry using a pore distribution measuring device (AutoPore IV 9500 manufactured by Micromeritics). The measurement conditions were as follows. [Measurement Conditions] Measuring device: Pore distribution measuring device (AutoPore IV 9500 manufactured by Micromeritics) Measurement range: 0.0036 to 10.3 μm Number of measurement points: 120 points Mercury contact angle: 140 degrees Mercury surface tension: 480 dyne / cm

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

[0196] For Examples 1 to 3 and Comparative Examples 1 to 3, the pore distributions of the obtained zirconia-based porous bodies are shown in FIGS. 1 to 6.

[0197] [Hardness Measurement] The zirconia-based porous bodies (powders) of the examples and comparative examples were embedded in an epoxy resin, subjected to cross-section processing, and used as samples for evaluation. The hardness evaluation was performed using a Nano Indenter manufactured by KLA Tencor. The evaluation was performed at a penetration depth of 50 nm using a diamond Berkovich indenter. The measurement was performed by a method compliant with ISO14577. The results are shown in Tables 1 and 2.

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

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

[0200] [Measurement of pore size distribution based on the BJH method after crushing treatment] Regarding the zirconia-based porous bodies of the examples and comparative examples, the crushing treatment was performed under the following crushing conditions. [Crushing treatment conditions] 30 g of the zirconia-based porous body and 300 ml of pure water were put into a 500 ml beaker and dispersed for 5 minutes at 550 W and an amplitude of 37% using an ultrasonic homogenizer "Sonifier SFX550" (manufactured by Nippon Emason Co., Ltd.). Then, it was dried at 110 °C for 24 hours.

[0201] Thereafter, using the pore size distribution measuring device "Belsorp mini II (manufactured by MicrotracBEL)", the pore size distribution was obtained by the BJH method. The measurement conditions were the same as those for the measurement of the pore size distribution based on 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 maintenance rate X of the pore volume. The maintenance rate X of the pore volume was obtained by the following formula. <Maintenance 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 Mac Science, "Macsorb"). 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] The zirconia-based porous bodies of the examples and comparative examples were heat-treated at 1000 °C for 3 hours in an air atmosphere at atmospheric pressure (0.1013 MPa). The specific surface area of the zirconia-based porous body after heat treatment at 1000 °C for 3 hours was measured by the BET method using a specific surface area meter (manufactured by Mac Science, "Macsorb"). The results are shown in Tables 1 and 2.

[0206] [Measurement of specific surface area (specific surface area B) before crushing treatment and after heat treatment at 1100 °C for 3 hours] The zirconia-based porous bodies of the examples and comparative examples were heat-treated at 1100 °C for 3 hours in an air atmosphere at atmospheric pressure (0.1013 MPa). The specific surface area of the zirconia-based porous body after heat treatment at 1100 °C for 3 hours was measured by the BET method using a specific surface area meter (manufactured by Mac Science, "Macsorb"). The results are shown in Tables 1 and 2.

[0207] [Measurement of Specific Surface Area (Specific Surface Area A-3) after Crushing Treatment and before Heat Treatment] For the zirconia-based porous bodies of the examples and comparative examples, crushing treatment was performed under the following crushing conditions. [Crushing Treatment Conditions] 30 g of the zirconia-based porous body and 300 ml of pure water were put into a 500 ml beaker, and dispersion was carried out for 5 minutes at 550 W and an amplitude of 37% using an ultrasonic homogenizer "Sonifier SFX550" (manufactured by Nippon Emason Co., Ltd.). Then, it was dried at 110 °C for 24 hours.

[0208] Thereafter, measurement was carried out by the BET method using a specific surface area meter ("Macsorb" manufactured by Mountech). The results are shown in Table 1 and Table 2.

[0209] [Measurement of Specific Surface Area (Specific Surface Area A-2) after Crushing Treatment and after Heat Treatment at 1000 °C for 3 Hours] For the zirconia-based porous bodies of the examples and comparative examples, crushing treatment was performed under the following crushing conditions. [Crushing Treatment Conditions] 30 g of the zirconia-based porous body and 300 ml of pure water were put into a 500 ml beaker, and dispersion was carried out for 5 minutes at 550 W and an amplitude of 37% using an ultrasonic homogenizer "Sonifier SFX550" (manufactured by Nippon Emason Co., Ltd.). Then, it was dried at 110 °C for 24 hours.

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

[0211] [Measurement of Specific Surface Area (Specific Surface Area A) after Crushing Treatment and after Heat Treatment at 1100 °C for 3 Hours] For the zirconia-based porous bodies of the examples and comparative examples, crushing treatment was performed under the following crushing conditions. [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 them for 5 minutes at 550 W and an amplitude of 37% using an ultrasonic homogenizer "Sonifier SFX550" (manufactured by Nippon Emerson Co., Ltd.). Then, dry at 110 °C for 24 hours.

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

[0213] In addition, Tables 1 and 2 also show the maintenance rate Y of the specific surface area, the maintenance rate Y-2 of the specific surface area, and the maintenance rate Y-3 of the specific surface area. The maintenance rate Y of the specific surface area, the maintenance rate Y-2 of the specific surface area, and the maintenance rate Y-3 of the specific surface area were obtained by the following formula. <Maintenance rate Y of specific surface area> [(Specific surface area A) / (Specific surface area B)] <Maintenance rate Y-2 of specific surface area> [(Specific surface area A-2) / (Specific surface area B-2)] <Maintenance rate Y-3 of specific surface area> [(Specific surface area A-3) / (Specific surface area B-3)]

[0214] [Measurement of particle diameter D 50 (Before crushing treatment)] Put 0.15 g of the zirconia-based porous body (powder) of the examples and comparative examples and 40 ml of a 0.2% aqueous sodium hexametaphosphate solution into a 50 ml beaker, disperse them for 5 minutes at a frequency of 28 kHz using an ultrasonic cleaner "VS-100 III" (manufactured by Vervo Clear Co., Ltd.), and then put them into a device (laser diffraction particle size distribution measuring device ("SALD-2300" manufactured by Shimadzu Corporation)) for measurement. The results are shown in Tables 1 and 2.

[0215] [Measurement of particle diameter D 50 after crushing treatment] For the zirconia-based porous bodies of the examples and comparative examples, crushing treatment was performed under the following crushing conditions. <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 them for 5 minutes at 550 W and an amplitude of 37% using an ultrasonic homogenizer "Sonifier SFX550" (manufactured by Nippon Emason Corporation).

[0216] Next, put it into a device (laser diffraction particle size distribution measuring device ("SALD-2300", manufactured by Shimadzu Corporation)) and measure it. The results are shown in Table 1 and Table 2.

[0217]

Table 1

[0218]

Table 2

Claims

1. 40% by mass or more of zirconia; 5% by mass or more and 60% by mass or less of an oxide of a rare earth element; Including, A zirconia-based porous body, characterized in that, in a pore size distribution determined by mercury intrusion porosimetry, it satisfies all of the following (1) and (2): (1) The maximum value of the peak in the range of 10 nm or more and less than 300 nm is 1.0 ml / g or more and 4.0 ml / g or less. (2) The pore volume of pores having a diameter of 300 nm or more and 100,000 nm or less is 0.85 ml / g or less.

2. 40% by mass or more of zirconia; 5% by mass or more and 60% by mass or less of an oxide of a rare earth element; Including, In terms of pore size distribution based on mercury intrusion porosimetry, all of the following (1) and (2) are satisfied: A zirconia-based porous body, characterized in that the number of peaks present in the range of 10 nm or more and less than 300 nm in the pore size distribution based on the mercury intrusion method is one. (1) The maximum value of the peak in the range of 10 nm or more and less than 300 nm is 1.0 ml / g or more and 4.0 ml / g or less. (2) The pore volume of pores having a diameter of 300 nm or more and 100,000 nm or less is 1.00 ml / g or less.

3. When the pore volume in the range of 10 nm to 200 nm 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 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, 3. The zirconia porous body according to claim 1, wherein the pore volume retention rate X represented by the following formula (4) is 0.80 or more and 1.10 or less: <Crushing treatment conditions> 30 g of the zirconia porous body and 300 ml of pure water are placed in a 500 ml beaker, and dispersed for 5 minutes using an ultrasonic homogenizer, followed by drying at 110° C. for 24 hours. <Pore volume maintenance rate X> [(Pore volume A) / (Pore volume B)] Formula (4)

4. The specific surface area after the crushing treatment under the following crushing treatment conditions and heat treatment at 1100° C. for 3 hours in an air atmosphere at atmospheric pressure is defined as specific surface area A, and the specific surface area before the crushing treatment and heat treatment at 1100° C. for 3 hours in an air atmosphere at atmospheric pressure is defined as specific surface area B. The specific surface area A is 15 m ２ / g or more 60m ２ / g or less, 3. The zirconia porous body according to claim 1, wherein a retention 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> 30 g of the zirconia porous body and 300 ml of pure water are placed in a 500 ml beaker, and dispersed for 5 minutes using an ultrasonic homogenizer, followed by drying at 110° C. for 24 hours. <Specific surface area maintenance rate Y> [(Specific surface area A) / (specific surface area B)] Formula (5)

5. After heat treatment at 1000°C for 3 hours under atmospheric pressure in an air atmosphere, the specific surface area is 20 m ２ / g or more 80m ２ 3. The zirconia porous body according to claim 1, wherein the zirconia porous body has a molecular weight of 1 / g or less.

6. A material having a specific surface area of ​​30 m ２ / g or more 120m ２ 3. The zirconia porous body according to claim 1, wherein the zirconia porous body has a molecular weight of 1 / g or less.

7. Step 1: adding a zirconium salt solution and a sulfating agent simultaneously to heated water to obtain a basic zirconium sulfate-containing slurry; A step 2 of removing unreacted zirconium salt and soluble zirconium salt; Step 3 of 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; A step 4 of obtaining a zirconia-based porous body by heat-treating the zirconium-containing hydroxide obtained in the step 3.

3. The method for producing a zirconia porous body according to claim 1, further comprising the steps of:

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