JP2014061461A - Exhaust gas cleaning catalyst, method for manufacturing an exhaust gas cleaning catalyst, and exhaust gas cleaning catalyst component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas cleaning catalyst excellent in terms of heat resistance and cleaning performance using unprecedentedly and radically economized quantities-in-use of rare earth elements; a method for manufacturing an exhaust gas cleaning catalyst; and an exhaust gas cleaning catalyst component.SOLUTION: The provided exhaust gas cleaning catalyst includes a mixture consisting of Oxide 1 including a phase of a perovskite structure, bearing a composition expressed by the following formula (1), and having an average particle diameter of 0.2 μm or less and Oxide 2 including at least one type selected from the group consisting of YO, LaO, CeO, and NiO, through YOindispensably, and having an average particle diameter of 0.1 μm or less in a state where the combined sum of Y, La, Ce and Ni of Oxide 2 with respect to A1 of Oxide 1 is 5 mol% or more and 30 mol% or less and where at least one type of noble metal selected from the group consisting of Pd, Pt, and Rh is being included, supported on the mixture of Oxide 1 and Oxide 2 : A1{FeB1C1}O(Formula 1) (A1 is one or two types of elements selected from the group consisting of Ba, Sr, and Ca, whereas 1.0≤a1≤1.1 holds).

Description

  The present invention relates to an exhaust gas purification catalyst for purifying carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (HC) in combustion exhaust gas, a method for producing the exhaust gas purification catalyst, and an exhaust gas purification catalyst. It relates to members. In particular, an exhaust gas purification catalyst for purifying carbon monoxide (CO), nitrogen oxides (NOx), and unburned hydrocarbons (HC) discharged from an internal combustion engine such as an automobile engine, a method for producing an exhaust gas purification catalyst, And an exhaust gas purification catalyst member.

The gas discharged from an internal combustion engine such as an automobile engine contains CO, NOx, and HC, which are converted into carbon dioxide (CO ₂ ), nitrogen (N ₂ ), and water (H ₂ O). Catalytic techniques for reducing CO, NOx, and HC emissions are generally known. Such a catalyst technology is used not only for exhaust gas from an internal combustion engine but also for other combustion exhaust gas.

  As a three-way catalyst that simultaneously purifies CO, NOx, and HC in automobile exhaust gas, a catalyst that combines noble metals such as Pt, Pd, and Rh is widely used. These noble metals are supported as fine particles on the surface of activated alumina (γ-alumina, ρ-alumina, χ-alumina, η-alumina, δ-alumina, κ-alumina, θ-alumina, amorphous alumina, etc.) oxide particles. Further, it is used after being coated on a honeycomb of metal or ceramic.

  The three-way catalyst works effectively near the stoichiometric air-fuel ratio, but in order to expand the effective air-fuel ratio width (window), oxygen storage materials such as cerium oxide, which is a rare earth oxide, are included to improve catalyst performance. Improvements are also being made. For example, Patent Document 1 discloses a method of adding an appropriate amount of ceria to a noble metal / activated alumina oxide catalyst. The catalyst performance is improved by adding oxygen storage capacity by ceria, but the amount of noble metals has not been reduced.

As oxides having oxygen storage performance other than ceria, composite oxides have been studied, and in particular, composite oxides having a perovskite structure containing rare earth elements have been studied. An oxide having a perovskite structure is represented as ABO _3, and the portion A (A site) contains a rare earth element or an alkaline earth metal element, and the portion B (B site) mainly contains transition elements. In addition, it can contain many elements. For example, Patent Document 2 discloses a catalyst in which a complex oxide having heat resistance, a perovskite complex oxide that must contain a rare earth element as an A site constituent element, and a noble metal coexist. Yes. In this publication, a perovskite type complex oxide is supported on a complex oxide having heat resistance. However, according to the example, the perovskite structure contains 50% or more of the so-called A site and a large amount of rare earth elements. Yes.

In addition, in order to obtain higher catalyst characteristics, Patent Document 3 does not include a complex oxide having heat resistance, and includes a perovskite type complex including a rare earth element such as (La, Sr) FeO ₃ or (La, Sr) MnO _3. Although it is disclosed that a noble metal element is supported on an oxide, in the examples, 80% or more of the A sites are rare earth elements. Furthermore, the composition and additive elements of the (La, Sr) FeO ₃ and (La, Sr) MnO ₃ have been studied, and their durability and heat resistance have been improved. It is contained in a large amount as described above (Patent Document 4). Furthermore, in order to improve the durability of the catalytic activity of the noble metal, a composite oxide such as La (Fe, Rh) O _{3 in} which the noble metal Rh is incorporated into the perovskite lattice and the A site is La of the rare earth element is disclosed. (Patent Literature 5, Patent Literature 6).

  As described above, the perovskite complex oxide can select many kinds of elements as constituent elements. However, in order to effectively improve the catalytic performance of the three-way catalyst and to obtain heat resistance, a relatively expensive La It is essential to contain a large amount of rare earth elements such as the main component of the perovskite complex oxide, and there is room for improvement in cost. In recent years, the destabilization of supply of so-called rare metals containing rare earth elements has become a major problem, and reduction of the amount of rare earth elements used is an important issue.

As a technique aiming at solving the problems of the perovskite complex oxide, a material containing no rare earth element has been studied (Patent Document 7). In this publication, A _α B _1-x B ′ _x O _3-δ (A is Ba and Sr, B is Fe and Co, B ′ is one element selected from Nb, Ta, and Ti, or 2 By changing the perovskite crystal structure composite oxide, which is a combination of elements of at least species, to a specific surface area of less than 10 m ² / g, the change in specific surface area at high temperatures is small, resulting in a change in characteristics during the use of the catalyst. A small and highly heat-resistant catalyst has been realized. However, from the inventor's experience, such a purification catalyst has problems in purifying characteristics at low temperatures and purifying characteristics under conditions where the time change of the concentration of CO in exhaust gas is fast and the response speed of the catalyst is required. It has been found that there are many cases where this occurs. In addition, since the oxide supporting the noble metal has a low specific surface area, it is found that the particle size of the noble metal is likely to be coarsened in the process of using the catalyst, and the heat resistance of the catalyst may be problematic. It was.

On the other hand, the conventional three-way catalyst is manufactured by a so-called solution method in which the raw material is dissolved in a solvent, homogenized, and then subjected to processes such as gelation and precipitation formation, followed by drying and baking to obtain an oxide. It is common to obtain a high specific surface area powder to achieve high purification properties. For example, Patent Document 8 discloses a catalyst in which palladium is contained in a defective perovskite complex oxide having a specific surface area of 10 m ² / g or more as a three-way catalyst for the purpose of improving catalytic activity and heat resistance. Further, there is disclosed a catalyst characterized in that 10 to 50% of the palladium is solid-dissolved in the defective perovskite composite oxide, and the remaining palladium is supported on the defective perovskite composite oxide in the PdO or Pd state. The defect perovskite complex oxide is produced by a kind of coprecipitation method of the solution method. According to the experience of the present inventors, the catalyst produced by such a solution method has a relatively excellent purification activity in the initial stage, but is easily sintered at a high temperature, and the specific surface area is reduced during use. There is a problem that the catalyst activity is lowered, and it tends to be deteriorated by solid-phase reaction with another coexisting oxide, resulting in low heat resistance. In addition, production by a solution method such as a coprecipitation method is complicated in operation and disadvantageous in terms of cost.

JP 54-159391 A JP-A-1-168343 JP 2006-36558 A JP 2003-175337 A JP 2004-41866 A JP 2004-41867 A JP 2007-160149 A Japanese Patent Laid-Open No. 62-269747

  As described above, in the three-way catalyst using the composite oxide having the conventional perovskite structure for purifying CO, Nox, and HC in the combustion exhaust gas, in order to effectively improve the catalyst performance and obtain heat resistance As a main component of the perovskite type complex oxide, it has been practically essential to contain a large amount of a relatively expensive rare earth element. In addition, a catalyst that does not contain a rare earth element as a main component of the perovskite complex oxide has been developed to increase the heat resistance of the catalyst by not increasing the specific surface area of the catalyst. There remains a problem with the purification performance in Japan. Furthermore, in the production of these catalysts, it is common to use a solution method that has problems in heat resistance of the product, ease of production operation, cost, and the like.

  Therefore, in order to solve the above-described problems of the prior art, the present invention greatly reduces the amount of rare earth elements used, and has excellent heat resistance and purification performance. Exhaust gas purification catalyst production method and exhaust gas purification catalyst An object is to provide a purification catalyst member.

  The inventors examined improvement in heat resistance of the perovskite complex oxide. Among them, the rare earth element is not contained as a component in the perovskite complex oxide, but the rare earth oxide is present as a second phase different from the perovskite complex oxide, and the A site of the perovskite complex oxide is present. It has been found that if the catalyst is composed only of an alkaline earth metal element, the purification characteristics of the catalyst are further improved, heat resistance can be secured, and as a result, the amount of rare earth element used can be reduced.

Further, rare earth oxides Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ , and the like can be used as oxides that have low reactivity and can improve the heat resistance of the catalyst even when coexisting with the perovskite complex oxide as the second phase. And it discovered that there was NiO of a transition metal oxide. Among these, Y ₂ O ₃ was particularly effective for improving heat resistance. Furthermore, in order to obtain the effect of addition of the second phase with respect to heat resistance, it was important to control the perovskite-type composite oxide and the particle size of the second phase to a specific range, respectively.

On the other hand, as described above, even when Y ₂ O ₃ or the like is present as the second phase, the heat resistance of the catalyst varies depending on the composition of the perovskite complex oxide, and high heat resistance is obtained. It was found that heat resistance may be low. In particular, when the A site of the perovskite complex oxide is deficient with respect to the B site (A / B <1), or when a large amount of Ba is included as a constituent element of the A site, the effect of the addition of the second phase Was difficult to obtain, and the heat resistance was greatly reduced. As a result of the study, the reason why the heat resistance is reduced is that the rare earth oxide added as the second phase reacts with the perovskite complex oxide to form a solid solution, and the heat resistance improvement effect is reduced. It has been found. Based on these findings, by setting the composition of the perovskite complex oxide within a specific range, stable and high heat resistance can be obtained, and the amount of second phase added such as rare earth oxide can be greatly reduced. I found.

  Further, when Ta, Nb, or the like is added as a component of the perovskite complex oxide, a part of the perovskite complex oxide is phase-separated at the formation stage of the perovskite complex oxide, and the perovskite complex oxide is grown. It has been found that it acts as an inhibitor against specific surface area reduction. It was also found that they are effective in further improving the heat resistance of the catalyst, and as a result, the amount of the second phase such as rare earth oxide can be further reduced.

In addition, in the production of the present catalyst, it is difficult to ensure the heat resistance of the catalyst when a commonly used solution method is used. This is considered to be because the uniformity of the raw material becomes too high in the solution method and it is difficult to disperse the second phase Y ₂ O ₃ or the like with an appropriate particle size. Therefore, in the present invention, the production by the solution method is rather counterproductive, and the combination of the solid phase synthesis method and the pulverization method, which is a low-cost oxide production method, adds the perovskite type complex oxide and The inventors have found that the particle size of the second phase can be easily controlled and that higher characteristics can be obtained, and the present invention has been achieved.

  That is, the gist of the present invention is as follows.

[1] Oxide 1 having a phase of perovskite structure and having an average particle size of 0.2 μm or less represented by the following (formula 1), Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ , NiO A mixture of at least one selected from Y ₂ O ₃ and oxide 2 having an average particle size of 0.1 μm or less,
A1 _a1 {Fe _(1-b1-c1) B1 _b1 C1 _c1 } O _3-δ (Formula 1)
(Here, A1 is one or two elements selected from Ba, Sr, and Ca, and B1 and C1 may not be arranged. However, when B1 is arranged, one or two selected from Co and Cu are used. In the case of disposing the element C1, one or more elements selected from Ti, Nb, Ta to Ta or Nb, 1.0 ≦ a1 ≦ 1.1, 0 ≦ b1 ≦ 0. 25, 0 ≦ c1 ≦ 0.2, δ is a value determined by the history of the material and satisfies 0 ≦ δ <3) From Pd, Pt and Rh supported on the mixture of oxide 1 and oxide 2 The average particle size of the oxide 2 is smaller than the average particle size of the oxide 1 and the total amount of Y, La, Ce and Ni of the oxide 2 is the oxide 1 A catalyst for exhaust gas purification, which is 5 mol% or more and 30 mol% or less with respect to A1.

[2] An oxide 1 ′ having a perovskite structure phase as the oxide 1 and an average particle size of 0.2 μm or less and a composition represented by the following (formula 2), and an average particle size of 0 as the oxide 2 The mixture of Y ₂ O ₃ that is not more than 1 μm, and the amount of Y in Y ₂ O ₃ is 5 mol% or more and 25 mol% or less with respect to A2 of the oxide 1 ′. Exhaust gas purification catalyst.
A2 _a2 {Fe _(1-b2-c2) Cu _b2 C2 _c2 } O _3-δ (Formula 2)
(Here, A2 is one or two elements selected from Sr and Ca, and Cu and C2 may not be arranged, but if there is an element arranged in C2, be sure to change Ta or Nb from Ti, Nb, or Ta. One or more elements selected including, 1.0 ≦ a2 ≦ 1.05, 0 ≦ b2 ≦ 0.2, 0 ≦ c2 ≦ 0.2, δ is a value determined by the history of the material, 0 ≦ δ <3 is satisfied)

[3] The oxide 1 ″ having a perovskite structure phase as the oxide 1 and having an average particle size of 0.2 μm or less represented by the following (formula 3), and the oxide 2 as an average particle [1] or a mixture containing Y ₂ O ₃ having a diameter of 0.1 μm or less, wherein the amount of Y of Y ₂ O ₃ is 5 mol% or more and 15 mol% or less with respect to A3 of the oxide 1 ″. The exhaust gas-purifying catalyst according to [2].
A3 _a3 {Fe _(1-b3-c3) Cu _b3 Ta _c3 } O _3-δ (Formula 3)
(Here A3 may not contain Cu, one or two elements selected from Sr and Ca. 1.0 ≦ a3 ≦ 1.05, 0 ≦ b3 ≦ 0.2, 0.1 ≦ c3. ≦ 0.2, δ is a value determined by the history of the material and satisfies 0 ≦ δ <3)

[4] The oxide 1 ′ ″ having a perovskite structure phase as the oxide 1 and having an average particle size of 0.2 μm or less and the composition represented by the following (formula 4), and the oxide 2 as an average The mixture includes a mixture with Y ₂ O ₃ having a particle size of 0.1 μm or less, and the amount of Y of Y ₂ O ₃ is 10 mol% or more and 20 mol% or less with respect to Sr of the oxide 1 ″ ′ [1 ] The exhaust gas-purifying catalyst according to any one of [3] to [3].
Sr _a4 {Fe _(1-b4) Cu _b4 } O _3-δ (Formula 4)
(Cu may not be included, but here 1.0 ≦ a4 ≦ 1.05, 0 ≦ b4 ≦ 0.2, δ is a value determined by the history of the material, and satisfies 0 ≦ δ <3)

[5] The exhaust gas according to any one of [1] to [4], wherein the exhaust gas purification catalyst has a specific surface area of at least 7 m ² / g after heat treatment at 900 ° C. for 5 hours in the atmosphere. Purification catalyst.

[6] A method for producing the exhaust gas-purifying catalyst according to any one of [1] to [5],
One or more carbonate or hydroxide powders selected from carbonates and hydroxides of alkaline earth metal elements of oxide 1, oxide 1 ′, oxide 1 ″ or oxide 1 ′ ″ , Oxide 1, oxide 1 ′, oxide 1 ″ or oxide 1 ′ ″, oxide powders of constituent elements other than alkaline earth elements, and the average grain size of oxide constituting oxide 2 A mixture with a powder having a diameter of 0.5 μm or less is fired at a plurality of temperatures selected from 900 ° C. to 1200 ° C. to obtain a fired mixture of oxide 1 and oxide 2, and then the fired mixture is made of ceramics. A method for producing an exhaust gas-purifying catalyst, which is pulverized by grinding with a ball until the specific surface area becomes at least 20 m ² / g.

[7] A method for producing the exhaust gas-purifying catalyst according to any one of [1] to [5], wherein the oxide 1, the oxide 1 ′, the oxide 1 ″, or the oxide 1 ′ ″ At least one carbonate or hydroxide powder selected from carbonates and hydroxides of alkaline earth metal elements, and oxide 1, oxide 1 ′, oxide 1 ″ or oxide 1 ″ After firing a mixture of oxides of constituent elements other than the alkaline earth element of ′ at a temperature selected from 900 ° C. to 1200 ° C. to obtain a phase having a perovskite structure, oxide 2 is obtained. Exhaust gas purification by adding and mixing powders of constituent oxides having an average particle size of 0.5 μm or less, and pulverizing the added mixture by pulverization using ceramic balls until the specific surface area becomes at least 20 m ² / g For producing a catalyst for use.

  [8] Exhaust gas purification according to [6] or [7], wherein at least one precious metal selected from Pd, Pt, and Rh is supported on the pulverized fired mixture or the pulverized additive mixture. For producing a catalyst for use.

  [9] An exhaust gas purification catalyst member comprising the exhaust gas purification catalyst according to any one of [1] to [5] supported on a base material.

  The exhaust gas purification catalyst and exhaust gas purification catalyst member of the present invention have excellent purification performance for CO, Nox, and HC in the exhaust gas, and also have high heat resistance even when the amount of relatively expensive rare earth elements used is reduced as compared with the prior art. And high temperature durability. Furthermore, the exhaust gas purifying catalyst of the present invention can be easily produced by a combination of a solid phase synthesis method and a pulverization method, which are low in production cost. Since the catalyst of the present invention has high heat resistance, not only the amount of rare earth element used but also the amount of noble metal used can be reduced, the production cost is low, and a purification catalyst can be provided at low cost. Due to these effects, the exhaust gas purifying catalyst and the exhaust gas purifying catalyst member of the present invention are suitably used for purifying CO, Nox, and HC contained in the exhaust gas of an internal combustion engine such as an automobile.

  Next, the present invention will be described in detail.

The catalyst of the present invention contains a perovskite-type composite oxide and a second phase centered on a rare earth oxide such as Y ₂ O ₃ effective for improving the heat resistance of the composite oxide as a mixture. . Then, the composition of the perovskite complex oxide is set to a specific composition, and the particle size of the perovskite complex oxide and the particle size of the second phase are controlled. As a result, high heat resistance can be obtained despite the small amount of rare earth elements used. As a result, even after using the catalyst at a high temperature for a long period of time, a large specific surface area is maintained and high purification performance is maintained. For this reason, even if the amount of noble metal supported on the catalyst is small, it is possible to provide a catalyst that exhibits high purification performance for a long period of time.

The exhaust gas purifying catalyst of the present invention contains oxide 1 as a first constituent element. The composition of the oxide 1 is represented by (Formula 1) A1 _a1 {Fe _(1-b1-c1) B1 _b1 C1 _c1 } O _3-δ and has a phase of a perovskite structure. The average particle diameter of the oxide 1 is 0.2 μm or less.

  In (Formula 1), A1 is one or two elements selected from Ba, Sr, and Ca. B1 and C1 may not arrange elements, but when B1 is arranged, one or two elements selected from Co and Cu, and when C1 is arranged, Ti, Nb, Ta to Ta or Nb must be used. It is 1 type or 2 or more types of elements chosen including. a1 is 1.0 or more and 1.1 or less, b1 is 0 or more and 0.25 or less, c1 is 0 or more and 0.2 or less, δ is 0 or more and less than 3, and a cation (A1, Fe, B1, C1) This is a value that is determined so that the sum of the valences of the two becomes equal to the valence of the anion (O). δ is set according to the history of the material. Specifically, in the manufacturing process of the exhaust gas purifying catalyst, the temperature at which the synthesized perovskite complex oxide passes, the holding time at the temperature, the temperature change rate, and the atmosphere It can be set according to the type of gas.

Further, the exhaust gas purifying catalyst contains the oxide 2 as a second constituent element. The oxide 2 is at least one selected from Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ , and NiO, but necessarily contains Y ₂ O ₃ . The average particle diameter of the oxide 2 is 0.1 μm or less and smaller than the average particle diameter of the oxide 1.

Although oxide 1 and oxide 2 exist in a mixed state, the total amount of Y, La, Ce, and Ni in oxide 2 is 5 mol% or more and 30 mol% or less with respect to A 1 of oxide 1. . Furthermore, at least one kind of noble metal selected from Pd, Pt, and Rh is supported on the mixture. Further, the exhaust gas-purifying catalyst has heat resistance having a specific surface area of at least 7 m ² / g even after heat treatment at 900 ° C. for 5 hours in the atmosphere.

  In the oxide 1, A1 is one or two elements selected from Ba, Sr, and Ca. From the viewpoint of obtaining higher purification performance, the ratio of Sr in A1 is preferably 50 mol% or more, more preferably 80 mol% or more. From the viewpoint of heat resistance, the proportion of Ba in A1 is preferably less than 50 mol%, more preferably 20 mol% or less.

  a1 is 1.0 or more and 1.1 or less. When a1 is less than 1.0, the reactivity of the rare earth oxide added as oxide 2 with respect to the perovskite complex oxide increases, and the heat resistance of the catalyst decreases. Moreover, when a1 exceeds 1.1, the content of the phase having a structure different from that of the perovskite type increases, and the purification characteristics at a low temperature of 300 ° C. or lower tend to be lowered.

  B1 may be omitted, but higher purification performance can be obtained when B1 contains one or two elements selected from Co and Cu. On the other hand, when the content of the element is excessively increased, the heat resistance is lowered. For this reason, the range of b1 is 0.25 or less. The element B1 is more preferably Cu from the viewpoint of maintaining high heat resistance.

  C1 may be omitted, but if C1 contains one or more elements selected from Ti, Nb, Ta to Ta or Nb, the heat resistance of the catalyst can be further improved. . On the other hand, if c1 is increased beyond 0.2, the catalyst characteristics are deteriorated, which is not preferable. Nb or Ta is preferable as an element of C1 for improving heat resistance, and Ta is more preferable. Ti may be contained as C1, but its content is preferably 30 mol% or less in the elements added as C1.

  In order to obtain high catalyst characteristics, the average particle size of the oxide 1 needs to be 0.2 μm or less, and more preferably 0.15 μm or less. When the average particle size is larger than 0.2 μm, the purification property at low temperature is deteriorated. Moreover, although the lower limit of the average particle diameter is not particularly provided, the average particle diameter is practically 0.05 μm or more.

The oxide 2 is at least one selected from Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ , and NiO, but necessarily contains Y ₂ O ₃ . Among these, Y ₂ O ₃ has the highest heat resistance improvement effect. For this reason, the amount of Y ₂ O _{3 in} the oxide 2 is preferably 60 mol% or more with respect to the total amount of Y, La, Ce, and Ni.

  Further, from the viewpoint of improving heat resistance, the average particle diameter of the oxide 2 needs to be 0.1 μm or less and smaller than the average particle diameter of the oxide 1. When the average particle size is larger than 0.1 μm or larger than the average particle size of the oxide 1, the heat resistance of the catalyst is lowered. Although no particular lower limit is provided for the average particle diameter of the oxide 2, the average particle diameter is practically 0.05 μm or more.

  The amount of oxide 2 added is set so that the total amount of Y, La, Ce, and Ni in oxide 2 is 5 mol% or more and 30 mol% or less with respect to A1 of oxide 1. When the addition amount of the oxide 2 is less than this range, the heat resistance is lowered. Moreover, when there are more addition amounts than this range, cost will become high and purification performance will also fall.

  In the present invention, the particle sizes of the oxide 1 and the oxide 2 can be confirmed with a transmission electron microscope having an elemental analysis function, a scanning electron microscope, or the like. On the other hand, when manufacturing by the 1st manufacturing method (after-mentioned), the particle size distribution just before mixing of the oxide 1 and the oxide 2 can each be directly measured with a particle size distribution meter. Similarly, the particle size distribution of the raw material of the catalyst can be measured by the particle size distribution diameter. As the particle size distribution meter, a laser diffraction / scattering type particle size distribution measuring device is suitable. In the present invention, the volume average diameter of the sample is used as the average particle diameter.

  The catalyst of the present invention is excellent as an exhaust gas purification catalyst because at least one element selected from Pt, Pd, and Rh is supported on at least the mixture of oxide 1 and oxide 2 described above. Demonstrate performance. When the noble metal is not supported, the performance as an exhaust gas purification catalyst is low. Therefore, in the catalyst of the present invention, it is essential to support at least one element selected from Pt, Pd, and Rh.

  In addition, the supported noble metal element is present as a metal or oxide fine particle on the surface of the mixture of oxide 1 and oxide 2 when used as a catalyst, and becomes a constituent element of the perovskite complex oxide. Not. In other words, the catalyst of the present invention has a high catalytic activity in such a state, and therefore the amount of noble metal can be reduced.

  The amount of noble metal supported in the catalyst of the present invention is desirably in the range of 0.1% or more and 2% or less by mass percent with respect to the mixture of oxide 1 and oxide 2. When the noble metal is supported beyond this range, the cost of the catalyst becomes high and the coarsening of the noble metal easily proceeds when the catalyst is used. In addition, when the amount of the noble metal supported is smaller than the above range, the catalyst purification performance may be insufficient.

In the present invention, in order to obtain higher heat resistance, oxide 1 is composed of oxide 1 ′ whose composition is represented by (formula 2), B1 is Cu, and oxide 2 is Y ₂ O _3. Is preferred.
A2 _a2 {Fe _(1-b2-c2) Cu _b2 C2 _c2 } O _3-δ (Formula 2)

In (Formula 2), A2 is one or two elements selected from Sr and Ca. C2 is one or more elements selected from Ti, Nb, and Ta, but always contains Ta or Nb. 1.0 ≦ a2 ≦ 1.05, 0 ≦ b2 ≦ 0.2, 0 ≦ c2 ≦ 0.2 are satisfied, and δ is a value determined by the history of the material. In order to further improve the heat resistance, the upper limit value of b2 is preferably limited to 0.2. The amount of Y ₂ O ₃ added is in a range where the amount of Y is 5 mol% or more and 25 mol% or less with respect to A2 of the oxide 1 ′.

In order to obtain even higher heat resistance, it is preferable that the oxide 1 be an oxide 1 ″ whose composition is represented by (formula 3), C1 is Ta, and Ta is necessarily contained.
A3 _a3 {Fe _(1-b3-c3) Cu _b3 Ta _c3 } O _3-δ (Formula 3)

In (Formula 3), A3 is one or two elements selected from Sr and Ca. 1.0 ≦ a3 ≦ 1.05, 0 ≦ b3 ≦ 0.2, 0.1 ≦ c3 ≦ 0.2 are satisfied, and δ is a value determined by the history of the material. The lower limit value of c3 is 0.1, and Ta is always included. In this case, the amount of Y ₂ O ₃ added is in the range in which the amount of Y is 5 mol% or more and 15 mol% or less with respect to A3 of the oxide 1 ″, and the addition amount of the rare earth oxide can be further reduced. Is possible.

On the other hand, when importance is attached to obtaining higher catalyst characteristics, the oxide 1 is an oxide 1 ′ ″ whose composition is represented by (formula 4), A1 is Sr, and C1 such as Ta is not included. Is preferred.
Sr _a4 {Fe _(1-b4) Cu _b4 } O _3-δ (Formula 4)

In (Expression 4), 1.0 ≦ a4 ≦ 1.05 and 0 ≦ b4 ≦ 0.2 are satisfied, and δ is a value determined by the history of the material. In this case, the amount of Y ₂ O ₃ added is in a range where the amount of Y is 10 mol% or more and 20 mol% or less with respect to Sr of the oxide 1 ′ ″. The amount b4 of Cu added is in the range of 0 to 0.2. However, in order to obtain higher catalyst characteristics, b4 is preferably in the range of 0.1 to 0.2.

The heat resistance of the catalyst can be evaluated by the specific surface area of the catalyst after being subjected to heat treatment. The specific surface area of the catalyst can be determined by the BET method using nitrogen gas adsorption. As a measure of the high heat resistance of the catalyst, the specific surface area of the catalyst after heat treatment at 900 ° C. for 5 hours in air is preferably 7 m ² / g or more. More preferably, the lower limit of the specific surface area is 8 m ² / g, more preferably 10 m ² / g. If the specific surface area after heat treatment is lower than this range, the heat resistance of the catalyst may not be sufficient, and it may be difficult to continue to provide high purification performance during the period of use of the catalyst. is there. The upper limit value of the specific surface area after the heat treatment is actually in the range of the specific surface area before the heat treatment, and preferably 70% of the specific surface area before the heat treatment.

  In order to obtain the effects of the present invention, the method for producing a mixture of oxide 1 and oxide 2 of the catalyst of the present invention is an important factor. Usually, a so-called solution method using a raw material such as an alkoxide is generally used as a production method used for obtaining a catalyst of a perovskite complex oxide. Since the solution method is produced from a solution in which raw materials are uniformly dissolved, it is possible to obtain a perovskite structure by firing at a relatively low temperature, and as a result of low temperature firing, it is easy to produce a catalyst having a high specific surface area. .

  On the other hand, in the present invention, it is important to control the particle diameters of the oxide 1 which is a perovskite complex oxide and the oxide 2 added for improving heat resistance. In the solution method, it is difficult to produce the two phases mixed in this way by controlling the average particle size.

  On the other hand, the catalyst of the present invention comprises an alkaline earth metal carbonate and an alkaline earth metal water as a raw material of the alkaline earth metal element of oxide 1, oxide 1 ′, oxide 1 ″ or oxide 1 ′ ″. One or more carbonate or hydroxide powders selected from oxides are used; constituent elements other than alkaline earth elements of oxide 1, oxide 1 ′, oxide 1 ″ and oxide 1 ″ ′ As the raw material of the above and the raw material of the oxide 2, oxide powders of these constituent elements are used. These can be produced by mixing and firing, and finely pulverizing by a pulverization method using ceramic balls.

Next, the 1st manufacturing method of the catalyst of this invention is demonstrated.
The raw materials for Sr and Ca, which are A1 elements in the composition formula (formula 1), are one or more carbonates or hydroxides selected from alkaline earth metal carbonates and alkaline earth metal hydroxides, preferably BaCO _3. Carbonate or hydroxide selected from SrCO ₃ , CaCO ₃ , Ba (OH) ₂ .8H ₂ O, Sr (OH) ₂ .8H ₂ O, Sr (OH) ₂ and Ca (OH) ₂ can be used. Fe ₂ O ₃ can be used as a raw material for Fe; CoO, Co ₃ O ₄ , CuO, etc. can be used as a raw material for Co and Cu as B1 elements; as raw materials for Ti, Nb, and Ta as C1 elements; Can use oxides such as TiO ₂ , Nb ₂ O ₅ and Ta ₂ O ₅ .

Further, as the oxide 2 raw material, the average particle size 0.5 [mu] m _Y 2 _O 3 were adjusted to the _following, La ₂ O _3, CeO 2, NiO oxides such as can be used.

  In the firing process, the raw material of the oxide 1 reacts to form particles having a perovskite structure, but the particles grow large to several hundred μm or more. On the other hand, the oxide 2 does not react even in the firing process and does not change greatly from the particle size before firing. For this reason, the particle size of the oxide 2 is considerably smaller than the particle size of the oxide 1 in the state after firing. On the other hand, the raw material of the oxide 2 is less pulverized than the oxide 1 in the pulverization process after firing. Although the particle size of the oxide 2 is reduced by pulverization, the difference from the particle size of the oxide 1 tends to be reduced. For this reason, the average particle diameter of the raw material of the oxide 2 is desirably adjusted to 0.5 μm or less, more desirably 0.3 μm or less, and further desirably 0.1 μm or less.

  The oxide 2 does not react with the oxide 1 in the temperature (firing temperature) range in the firing step. Therefore, it is effective to adjust the average particle size of the oxide 2 in advance at the raw material stage to the particle size required for the product catalyst.

  After weighing the required amounts of the raw materials for oxide 1 and oxide 2, wet mixing is performed with a mill such as a ball mill using water or ethyl alcohol as a dispersion medium. In some cases, dry mixing without using a dispersion medium may be used. The obtained slurry is dried and crushed (in the case of dry mixing, this step is usually not necessary), and then put in a ceramic container made of alumina or the like and baked for several hours in the atmosphere. And a calcined mixture of oxide 2 is obtained.

  The firing temperature is 900 ° C. or higher and 1200 ° C. or lower. It is desirable to perform the firing a plurality of times at different temperatures. Moreover, it is desirable to grind | pulverize a powder with a mortar etc. between the 1st baking process and the 2nd baking process, and to remove a coarse grain. It is desirable that the firing temperatures of the firings that are performed a plurality of times be sequentially increased. Typically, the first baking is performed at 900 ° C., and the second baking is performed at 1100 ° C. Thereby, it becomes possible to produce a catalyst having excellent characteristics. If the firing temperature exceeds 1200 ° C., pulverization in the subsequent process becomes difficult. On the other hand, if the calcination temperature is lower than 900 ° C., the formation of the perovskite structure is insufficient and the necessary catalyst characteristics cannot be obtained.

By pulverizing the firing mixture of oxide 1 and oxide 2 obtained after firing, the average particle size of oxide 1 is 0.2 μm or less, and the average particle size of oxide 2 is 0.1 μm or less. And pulverize until the specific surface area is at least 20 m ² / g. Conventionally, it has been difficult to produce such a fine oxide powder having a high specific surface area by a pulverization method. On the other hand, the baked mixture in the present invention can be pulverized very easily by using a medium stirring type pulverizer such as a bead mill using a ceramic ball having a diameter of about 0.5 mm to 0.01 mm for pulverization. . Although specific surface area is possible to increase up to about 100 m ² / g, preferably not more than ^70m 2 / g. If the pulverization is advanced too much, the perovskite phase may be decomposed during the pulverization process, which is not preferable.

As a ceramic ball used for pulverization, it is preferable to use a ball made of zirconia from the viewpoint of less contamination of impurities due to wear of the ball. The pulverization of the fired mixture with the ceramic balls needs to be carried out until the specific surface area of the fired mixture becomes at least 20 m ² / g, and desirably it is raised to 25 m ² / g or more. If the specific surface area of the calcined mixture after pulverization is lower than the above range, the specific surface area becomes small in the process of using the obtained catalyst, and the problem that the catalyst characteristics become low tends to occur.

  Next, the 2nd manufacturing method of the catalyst of this invention is demonstrated. In this method, only the oxide 1 is first manufactured. This method is the same as the above method, and raw material mixing, drying, crushing, and firing in the atmosphere yield an oxide having a perovskite structure. The particles of oxide 1 at this stage are greatly grown to a particle size of several hundred μm or more due to the reaction of the raw materials.

The raw material of oxide 2 such as Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ , and NiO that has been adjusted to an average particle size of 0.5 μm or less in advance is added to and mixed with the obtained oxide 1. Further, the obtained additive mixture is pulverized by the pulverization method described below until the average particle size of the oxide 1 becomes 0.2 μm or less.

  Since the oxide 1 has a perovskite structure, its strength is low, and the oxide 1 is more easily pulverized than the oxide 2 in the pulverization process. Therefore, although the particle diameter of the oxide 2 is reduced by the pulverization, the oxide 1 is further pulverized and quickly becomes smaller. For this reason, even if the particle size of the raw material of oxide 2 added at the stage of pulverization is made smaller than the particle size of oxide 1, the difference between the particle sizes of oxides 1 and 2 tends to be reduced. is there. By adjusting the average particle diameter of the raw material of the oxide 2 to 0.5 μm or less, the particle diameters of the oxide 1 and the oxide 2 after pulverization can be within the range of the present invention. On the other hand, when the average particle diameter of the raw material of the oxide 2 is larger than 0.5 μm outside the above-mentioned conditions, the pulverization process of the oxide 1 may progress and become smaller than the oxide 2 in the pulverization process. It becomes difficult to make the particle diameters of the oxide 1 and the oxide 2 within the range of the present invention.

  In order to ensure that the particle diameters of the oxide 1 and the oxide 2 are within the range of the present invention, the average particle diameter of the raw material of the oxide 2 is desirably 0.3 μm or less, and more desirably 0.1 μm. It is as follows.

The additive mixture is pulverized using ceramic balls in the same manner as described above, and the specific surface area is 20 m ² / g or more, the average particle diameter of oxide 1 is 0.2 μm or less, and the oxidation is performed. The product 2 is pulverized until the average particle size of the product 2 becomes 0.1 μm or less.

  The powdered catalyst of the present invention can be obtained by supporting a noble metal such as Pt, Pd, Rh on the pulverized baked mixture or the pulverized additive mixture (also referred to as “pulverized mixture”). This pulverized mixture becomes a mixture of oxide 1 and oxide 2 in the exhaust gas purifying catalyst of the present invention.

  In the method of supporting Pt, Pd, and Rh on the pulverized mixture, dinitrodiammine platinum nitrate aqueous solution, palladium nitrate aqueous solution, rhodium nitrate aqueous solution, or the like can be suitably used as the raw material for Pt, Pd, and Rh. These required amounts are weighed to form a mixed solution, and a predetermined amount of the mixed solution is impregnated into a predetermined amount of the pulverized mixture of oxide 1 and oxide 2 and dried using a rotary evaporator or the like. Thereafter, heat treatment is performed in the atmosphere for several hours at a temperature of about 600 ° C. It is also possible to dissolve the noble metal salt in an alcohol such as ethanol and impregnate using an alcohol solvent.

  Next, the exhaust gas purification catalyst member of the present invention will be described.

  The exhaust gas purification catalyst member of the present invention is formed by supporting the above-described catalyst of the present invention on a base material. By supporting the catalyst on the substrate, the spatial concentration of the catalyst can be optimally controlled, and the catalyst surface can be effectively used at the contact surface with the exhaust gas. Furthermore, it is possible to prevent the catalyst particles from being scattered by being bonded to the base material. In addition, it is possible to obtain an effect of reducing influences such as excessive temperature increase, heat deterioration due to heat generation in the catalytic reaction, temperature decrease due to heat absorption, and activity decrease.

  As the substrate used in the exhaust gas purification catalyst member of the present invention, a ceramic or metal carrier, or a carrier in which they are in a honeycomb form can be suitably used. For example, cordierite is suitable as the ceramic, but the present invention is not limited to this. Moreover, as said metal, the ferritic stainless steel excellent in oxidation resistance is suitable, for example, However, This invention is not limited to this. When these ceramic or metal carriers are in the form of honeycomb, the ventilation resistance of the exhaust gas becomes smaller, and the effective area where the catalyst of the present invention comes into contact with the exhaust gas increases, which is more suitable as an exhaust gas purification catalyst member.

  The amount of the noble metal of the present invention supported on the substrate is preferably in the range of 0.01 g / L to 5 g / L with respect to the volume of the substrate (support). If the amount of noble metal is less than 0.01 g / L, sufficient purification performance may not be obtained. On the other hand, if the amount of noble metal exceeds 5 g / L, the purification performance may not be improved further or the ventilation resistance of the exhaust gas may increase.

  In order to produce the exhaust gas purification catalyst member of the present invention, the particles of the catalyst of the present invention are used together with a binder fixed to a carrier. First, a slurry in which a catalyst, a binder and the like are dispersed is prepared, and a ceramic or metal carrier is immersed in the slurry. Next, excess slurry on the surface of the carrier is removed by a method such as blowing off, and after drying, the carrier is heat-treated at a temperature of about 500 ° C. for several hours in the atmosphere. In the case of a honeycomb-shaped carrier, the slurry can be sucked up by devising a jig for mounting the honeycomb-shaped carrier so that the slurry is applied only to the inner wall of the carrier. When the catalyst-supported carrier is granular, it may be used by packing it in a column through which exhaust gas flows. In addition, when the catalyst-supported carrier has a honeycomb shape, it may be used by fixing or standing in the column by some method. For example, by placing inside the column a honeycomb with catalyst that is wrapped with heat insulating wool of alumina short fibers, the honeycomb can be fixed inside the column, and almost all of the exhaust gas is circulated through the catalyst layer and purified. The

  As the binder, a heat-resistant oxide or hydroxide can be used. As described above, the binder binds the catalyst particles and the like, and additionally has a function of giving high adhesion when the catalyst of the present invention is supported on the base material, as well as high temperature oxidation conditions. Since it exists stably even under, the performance as a binder is rarely deteriorated. Specifically, oxides and hydroxides such as alumina, activated alumina, boehmite, aluminum hydroxide, silica, silica-alumina, and zeolite are preferably used. In particular, activated alumina is more suitable because it is easily available and inexpensive.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

  In the examples of the present invention, the composition of the perovskite type complex oxide is calculated by the amount charged in the production, but this is different from the amount of the metal element in the charged compound and the product by chemical analysis. I confirmed that it matched.

  In this example, when the catalyst is produced by the first production method, the particle size distribution of the raw material of the oxide 2 is obtained by volume average using a particle size distribution measuring device such as SLAD-3000 manufactured by Shimadzu Corporation, MT3300 manufactured by Nikkiso, or UPA150. The diameter was measured and D50 was determined. On the other hand, in the catalyst after the pulverization step by the medium stirring pulverizer, the average particle diameters of oxide 1 and oxide 2 were evaluated by a transmission electron microscope such as JEM-2100F manufactured by JEOL. 100 or more oxides 1 and 2 were selected by element distribution analysis of the electron microscope, and the average particle size was determined by a line intercept method based on an electron micrograph. That is, a plurality of straight lines were drawn on the photograph, and the average value of the lengths of the straight line portions crossing each particle was calculated and used as the average particle diameter.

  Moreover, when manufacturing a catalyst with the 2nd manufacturing method, the particle size distribution before the grinding | pulverization process of the oxide 1 and the oxide 2 was measured with the particle size distribution measuring apparatus similarly to the above. On the other hand, in the catalyst after the pulverization step by the medium stirring pulverizer, the particle size distribution of the oxide 1 and the oxide 2 was evaluated by a transmission electron microscope in the same manner as described above.

  The specific surface area of the catalyst in this example was determined by the BET method by nitrogen gas adsorption using Belsorb manufactured by Nippon Bell Co., Ltd. The evaluation of the specific surface area was first performed at the stage before supporting the noble metal, and the ultimate specific surface area in the pulverization process was determined. Further, after a precious metal was supported on the pulverized mixture of oxide 1 and oxide 2 to prepare a powdered catalyst, the catalyst was placed in an alumina crucible and subjected to a heat treatment at 900 ° C. for 5 hours in an air atmosphere. The specific surface area was measured again. The specific surface area was defined as the specific surface area after the heat resistance test. The specific surface area of the pulverized mixture before supporting the noble metal and the specific surface area of the pulverized mixture after supporting the noble metal (specific surface area of the catalyst before the heat resistance test) are considered to be substantially the same. The specific surface area of the mixture (specific surface area of the catalyst before the heat resistance test) was not presented.

  In the evaluation of the catalyst characteristics in this example, a catalyst member having a catalyst supported on a metal honeycomb carrier was produced and measured. Specifically, all the catalysts were supported on a metal honeycomb carrier made of stainless steel foil by a wash coat, and a catalyst member was produced and measured. The amount of catalyst used in the purification performance evaluation of this example and comparative example was 5 to 6 g in terms of powder catalyst. In the installation of the catalyst-supported metal honeycomb carrier in the evaluation apparatus, the honeycomb was fixed inside the column by placing the honeycomb outer periphery wound with heat insulating wool of short alumina fibers inside the column.

Next, a method for evaluating catalyst performance will be described. The evaluation apparatus used here is a flow type reaction apparatus composed of stainless steel pipes. The model gas having the composition shown in Table 1 is introduced from the inlet side, and is distributed to the exhaust gas purification reaction section. To be discharged. The purification reaction part is heated by heating the model gas with an external heater and sending it to the exhaust gas purification reaction part. In the purification property evaluation, first, the metal carrier carrying the catalyst was held at 450 to 500 ° C. for 1 hour in an atmosphere under the stoichiometric conditions shown in Table 1, and then cooled to around room temperature. Subsequently, the metal carrier is set in the column of the evaluation apparatus, and while raising the temperature, the gas having the stoichiometric conditions shown in Table 1 is flowed, and the gas composition on the outflow side (after passing through the catalyst portion) is analyzed, and CO, The respective purification characteristics were evaluated by determining the rate of change of the HC and NOx concentrations. The space velocity was 100,000 hr ⁻¹ . The catalyst characteristics were evaluated by determining the temperature (T50) at which CO, HC, and NOx each had a purification rate of 50%.

  The amount of catalyst used in the purification performance evaluation of this example and comparative example was 5 to 6 g in terms of powder catalyst. In the installation of the catalyst-supported metal honeycomb in the evaluation apparatus, the honeycomb was fixed inside the column by placing the honeycomb outer periphery wound with heat insulating wool of alumina short fibers inside the column.

  T50 after the heat resistance test of the catalyst in this example was evaluated by the following method. The catalyst member having the catalyst supported on the honeycomb-shaped carrier was held in the atmosphere at 900 ° C. for 5 hours, and then cooled to near normal temperature. This was held at 450 to 500 ° C. for 1 hour in an atmosphere under the stoichiometric conditions shown in Table 1, and then cooled again to near normal temperature. What was heat-treated in this way was evaluated by the above evaluation method, and T50 was determined.

As for the purification characteristics of the catalyst, when the average value of T50 of CO, HC and NOx after the heat resistance test is 255 ° C. or less, the purification characteristics are excellent (◎), and when the average value is over 255 ° C. and 260 ° C. or less. The case where it was good (◯) and the temperature was higher than 260 ° C. and 265 ° C. or lower was acceptable (Δ), and the case where the temperature was higher than 265 ° C. or the purification rate did not reach 50% was regarded as a poor purification property (×). Further, when the change width of the average value of T50 (T50 increase width due to catalyst deterioration) is 10 ° C. or less, excellent heat resistance (（), and when it is more than 10 ° C. and 25 ° C. or less, good heat resistance (◯), 25 ° C. When the temperature was 40 ° C. or lower, heat resistance was acceptable (Δ). As a comprehensive judgment, ◎ when the purification property and heat resistance are both excellent, ○ + when it is good and good, ○ when it is good and good, ○ − when it is good and good, The case where it was possible was evaluated as △, and the case where even one was defective was evaluated as ×.

Example 1
With respect to oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.02 {Fe _0.9 Cu _0.1 } O _3-δ , the amount of Y in Y ₂ O _{3 is} as oxide 2 , Y ₂ O ₃ was added so as to be 20 mol% of Sr. Furthermore, the catalyst which carries 0.4 mass% Pd in this mixture was manufactured, and also the catalyst member was manufactured using this. And the catalyst performance was evaluated.

  First, a mixture of oxide 1 and oxide 2 was produced by the following method.

Granular SrCO ₃ , Fe ₂ O ₃ , CuO, and Y ₂ O ₃ were used as raw materials for Sr, Fe, Cu, and Y, respectively. Pre-grinding was performed so that the average particle diameter D50 of Y ₂ O ₃ was 0.1 μm. The raw materials are weighed so that the molar ratio is Sr: Fe: Cu: Y = 1.02: 0.9: 0.1: 0.204, and added to ethyl alcohol (dispersion medium). A slurry was obtained by wet mixing while pulverizing. The rotary evaporator solids were separated from the slurry and dried at approximately 120 ° C. for 1 hour. Next, the obtained dried product was crushed, put into a corner or container made of MgO ceramic, and baked in an electric furnace at 900 ° C. for 5 hours in the air to obtain a porous massive fired product. After the fired product was crushed, it was dry-pulverized with an automatic mortar, placed again in a corner or container made of MgO ceramic, and fired in an electric furnace at 1100 ° C. for 5 hours in the atmosphere. When the constituent phase of the obtained baked mixture was evaluated by powder X-ray diffraction method, it was found that the oxide 1 composed of a single phase having a perovskite structure and Y ₂ O ₃ well matched with 41-1105 of the Powder Diffraction File of ICDD. (Oxide 2) was mixed.

The fired mixture was pulverized for 3 hours in a bead mill using ethanol as a solvent, using zirconia beads having a diameter of 0.2 mm. It was 30 m < ² > / g when the specific surface area of the grind | pulverized baking mixture (crushed mixture) was measured. Moreover, when the average particle diameter of the oxide 1 and the oxide 2 in this grinding | pulverization mixture was measured, they were 0.07 micrometer and 0.05 micrometer, respectively.

  Next, 0.4 mass% Pd was supported on the pulverized mixture as follows.

  A predetermined amount of commercially available palladium nitrate was weighed and diluted with ethanol to obtain a diluted solution having a volume of about 100 mL. The diluted solution and 100 g of the pulverized mixture were put in a rotary evaporator, and first, defoamed while rotating and stirring at normal temperature and under reduced pressure. After returning to normal pressure and heating to about 50 ° C., it was dried under reduced pressure. After cooling to room temperature, the pressure was returned to normal pressure, the solid was taken out, and dried at about 120 ° C. for 5 hours. The obtained dried product was heat treated at 600 ° C. in the atmosphere for 5 hours, and then crushed into powder. By the above operation, a powdery catalyst having a Pd loading of 0.4 mass% was obtained.

The catalyst was placed in an alumina crucible, subjected to a heat treatment (heat resistance test) at 900 ° C. for 5 hours in an air atmosphere, and then the specific surface area was measured again, which was 11 m ² / g.

  Next, the catalyst obtained above was supported on a honeycomb-shaped metal carrier.

  By mass ratio, 10 parts by mass of the Pd-supported catalyst, 5 parts by mass of commercially available γ-alumina (activated alumina), 4 parts by mass of commercially available silica sol (trade name Snowtex C), 7 parts by mass of pure water, a commercially available melcellulose solution (solid content) 2.5% by mass) and an appropriate amount of antifoaming agent were mixed well to obtain a slurry.

  As the honeycomb-shaped metal carrier, a cylindrical stainless steel honeycomb carrier having a predetermined shape diameter of 25 mm, a height of 60 mm, and a cell pore size of 1 mm × 2 mm in the honeycomb cross section was used. The honeycomb-shaped carrier was held vertically, and an excessive amount of the slurry was uniformly deposited on the upper end surface of the honeycomb-shaped carrier, sucked from the lower end surface of the honeycomb-shaped carrier and applied to the inner wall of the honeycomb, and the excess slurry was removed. When the slurry adhered to the outer surface of the honeycomb-shaped carrier, the adhered slurry was wiped off before drying. While continuing the suction, the upper end surface of the honeycomb-shaped carrier was air blown and dried. The honeycomb carrier was turned upside down, and the slurry was applied to the inner wall of the honeycomb carrier and the drying operation was performed again. Thereafter, heat treatment was performed in the atmosphere at 600 ° C. for 1 hour to obtain a stainless steel honeycomb-shaped carrier carrying the catalyst powder of the present invention. The amount of Pd fixed on the honeycomb-shaped carrier was 0.63 g / L-carrier.

  When the exhaust gas purification performance of the above catalyst-supported stainless steel honeycomb-shaped carrier was measured, T50s of CO, THC, and NOx were 210 ° C., 229 ° C., and 250 ° C., respectively. The T50s of CO, THC, and NOx after the heat resistance test of the honeycomb-shaped carrier were 240 ° C., 257 ° C., and 279 ° C., respectively. The average value of T50 after these heat tests is 255 ° C., the purification characteristic is excellent (◎), the increase in the T50 heat test is 25 ° C., and the heat resistance is evaluated as good (◯). Met.

  The composition of oxide 1 constituting the catalyst is shown in Table 2; the conditions of oxide 2, the production conditions and physical properties of the catalyst are shown in Table 3, and the evaluation results of the catalyst performance are shown in Table 5, respectively.

(Example 2)
With respect to the oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.02 {Fe _0.8 Cu _0.2 } O _3-δ , the amount of Y in Y ₂ O ₃ as the oxide 2 is A catalyst in which 0.4 mass% of Pd is supported on a mixture in which Y ₂ O ₃ is added so that the amount of Sr is 10 mol%, and a honeycomb-like carrier using the catalyst, are prepared in the same manner as in Example 1. Manufactured with.

The constituent phases of the fired mixture were evaluated by powder X-ray diffraction. As a result, the oxide 1 composed of a single phase having a perovskite structure and the Y ₂ O ₃ (oxide) well matched with 41-1105 of the ICDD's Powder Diffraction File 2). It was 28 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Moreover, when the average particle diameter of the oxide 1 and the oxide 2 in this grinding | pulverization mixture was measured, they were 0.08 micrometer and 0.05 micrometer, respectively. The specific surface area of the powdery catalyst after the heat test was 10 m ² / g.

  Furthermore, after evaluating the catalyst performance, the honeycomb-shaped carrier was subjected to a heat resistance test, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were excellent (◎), good heat resistance (○), and overall judgment ○ +.

(Example 3)
In contrast to oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 {Fe _0.8 Ta _0.2 } O _3-δ , the amount of Y in Y ₂ O ₃ as oxide 2 is A catalyst in which 0.4 mass% of Pd was supported on a mixture in which Y ₂ O ₃ was added so as to be 15 mol% of Sr, and a catalyst member was produced by the same method as described above. .

When the constituent phases of the fired mixture were evaluated by powder X-ray diffractometry, the first phase almost identical to Sr {Fe _0.5 Ta _0.5 } O ₃ and the oxide 1 of Example 1 were almost identical. Oxide 1 composed of two types of perovskite structure composed of the second phase, and a mixed state of Y ₂ O ₃ (oxide 2) that closely matches 41-1105 of the ICDD's Powder Diffraction File It was.

It was 20 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Moreover, when the average particle diameter of the oxide 1 and the oxide 2 in this grinding | pulverization mixture was measured, they were 0.15 micrometer and 0.08 micrometer, respectively. The specific surface area of the powdery catalyst after the heat test was 15 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were excellent (◎), excellent heat resistance (◎), and overall judgment ◎.

Example 4
To oxide 1 having a composition having a perovskite-type crystal structure represented by _{Sr 1.0 {Fe 0.8 Cu 0.1 Ta} 0.1} O 3-δ, as the oxide _2, in Y 2 _{O 3} A catalyst in which 0.4 mass% of Pd is supported on a mixture in which Y ₂ O ₃ is added so that the amount of Y is 15 mol% of Sr, and a catalyst member using the same, are similar to the above. Produced by the method.

When the constituent phases of the fired mixture were evaluated by powder X-ray diffractometry, the first phase almost identical to Sr {Fe _0.5 Ta _0.5 } O ₃ and the oxide 1 of Example 1 were almost identical. Oxide 1 composed of two types of perovskite structure composed of the second phase, and a mixed state of Y ₂ O ₃ (oxide 2) that closely matches 41-1105 of the ICDD's Powder Diffraction File It was. It was 20 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Moreover, when the average particle diameter of the oxide 1 and the oxide 2 in this grinding | pulverization mixture was measured, they were 0.15 micrometer and 0.08 micrometer, respectively. The specific surface area of the powdery catalyst after the heat test was 14 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were excellent (◎), good heat resistance (○), and overall judgment ○ +.

(Example 5)
The amount of Y in Y ₂ O ₃ is 25 mol% of Sr as oxide 2 with respect to oxide 1 having a perovskite crystal structure represented by Sr _1.05 Fe _1.0 O _3-δ. as such, the mixture Y ₂ O ₃ is added, the catalyst is formed by carrying 0.4 mass% of Pt, and the catalyst member which was employed to prepare in the same manner as mentioned above.

The constituent phases of the fired mixture were evaluated by powder X-ray diffraction. As a result, the oxide 1 composed of a single phase having a perovskite structure and the Y ₂ O ₃ (oxide) well matched with 41-1105 of the ICDD's Powder Diffraction File 2). It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively. The specific surface area of the powdery catalyst after the heat test was 12 m ² / g.

  Further, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were good (◯), the heat resistance was good (◯), and the overall judgment was ○.

(Example 6)
In contrast to oxide 1 having a perovskite crystal structure whose composition is represented by (Sr _0.8 Ca _0.2 ) _1.0 {Fe _0.8 Cu _0.2 } O _3-δ , as the amount of Y in the ₂ O ₃ is 20 mol% based on the total of Sr and _Ca, the mixture Y 2 _{O 3} is added, the catalyst is formed by carrying 0.4 mass% of Rh, and this A catalyst member was produced in the same manner as described above. Here, CaCO ₃ powder was used as a raw material for Ca.

The constituent phases of the fired mixture were evaluated by powder X-ray diffraction. As a result, the oxide 1 composed of a single phase having a perovskite structure and the Y ₂ O ₃ (oxide) well matched with 41-1105 of the ICDD's Powder Diffraction File 2). It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively. The specific surface area of the powdery catalyst after the heat test was 13 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were excellent (◎), good heat resistance (○), and overall judgment ○ +.

(Example 7)
In contrast to oxide 1 having a perovskite crystal structure whose composition is represented by (Sr _0.8 Ca _0.2 ) _1.0 {Fe _0.8 Cu _0.1 Ta _0.1 } O _3-δ as _2, so that the amount of Y in Y 2 _{O 3} is 5 mol% based on the total of Sr and _Ca, the mixture Y 2 _{O 3} is added, formed by carrying 0.4 mass% of Pd A catalyst and a catalyst member using the catalyst were produced in the same manner as described above. Here, Ta ₂ O ₅ powder was used as a Ta raw material.

When the constituent phases of the fired mixture were evaluated by powder X-ray diffractometry, the oxide 1 composed of the Sr {Fe _0.5 Ta _0.5 } O ₃ phase was in good agreement with 41-1105 of the ICDD's Powder Diffraction File. It was in a mixed state of Y ₂ O ₃ (oxide 2). It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively. The specific surface area of the powdery catalyst after the heat test was 8 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were excellent (◎), good heat resistance (○), and overall judgment ○ +.

(Example 8)
Oxide 1 having a perovskite crystal structure whose composition is represented by (Sr _0.5 Ca _0.5 ) _1.1 {Fe _0.75 (Cu _0.5 Co _0.5 ) _0.25 } O _3-δ On the other hand, the oxide 2 is a mixture of Y ₂ O ₃ and La ₂ O _{3 in} a molar ratio of Y: La = 60: 40, and the total amount of Y and La is 30 mol% with respect to the total of Sr and Ca. A catalyst obtained by supporting 0.4 mass% of Pd in the mixture thus added and a catalyst member using the catalyst were produced in the same manner as described above. Here, Co ₃ O ₄ and La ₂ O ₃ powders were used as raw materials for Co and La. Further, the mixture of Y ₂ O ₃ and La ₂ O ₃ was preliminarily pulverized so that the average particle diameter D50 was 0.1 μm.

The constituent phases of the fired mixture were evaluated by powder X-ray diffractometry. As a result, the oxide 1 composed of a single phase having a perovskite structure, Y ₂ O ₃ well matched with 41-1105 of the Powder Diffraction File of ICDD, and 5 It was in a mixed state of oxide 2 made of La ₂ O ₃ that was in good agreement with -602. It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively. The specific surface area of the powdery catalyst after the heat test was 10 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were good (◯), the heat resistance was good (◯), and the overall judgment was ○.

Example 9
In contrast to oxide 1 having a perovskite crystal structure whose composition is represented by Ca _1.0 {Fe _0.9 Co _0.1 } O _3-δ , Y ₂ O ₃ and La ₂ O ₃ are Y as oxide 2 A catalyst in which 2.0 mass% of Pd is supported on a mixture in which a mixture having a molar ratio of La = 60: 40 is added so that the total amount of Y and La is 30 mol% with respect to Ca, And the catalyst member was manufactured by the method similar to the above using this.

The constituent phases of the fired mixture were evaluated by powder X-ray diffractometry. As a result, the oxide 1 composed of a single phase having a perovskite structure, Y ₂ O ₃ well matched with 41-1105 of the Powder Diffraction File of ICDD, and 5 It was in a mixed state of oxide 2 made of La ₂ O ₃ that was in good agreement with -602. It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively. The specific surface area of the powdery catalyst after the heat test was 11 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were good (◯), heat resistance was acceptable (Δ), and overall judgment was ○ −.

(Example 10)
For the oxide 1 having a perovskite type crystal structure represented by the composition (Sr _0.8 Ba _0.2 ) _1.05 Fe _1.0 O _3-δ , the oxide 2 contains Y in Y ₂ O _3. A catalyst in which 0.4 mass% of Pd is supported on a mixture in which Y ₂ O ₃ is added so that the amount of Sr is 5 mol% of Sr, and a catalyst member using the same, by the same method as described above Manufactured with.

The constituent phases of the fired mixture were evaluated by powder X-ray diffraction. As a result, the oxide 1 composed of a single phase having a perovskite structure and the Y ₂ O ₃ (oxide) well matched with 41-1105 of the ICDD's Powder Diffraction File 2). It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively. The specific surface area of the powdery catalyst after the heat test was 7 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were acceptable (Δ), the heat resistance was acceptable (Δ), and the overall judgment was Δ.

(Example 11)
In contrast to oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 {Fe _0.8 (Ta _0.5 Nb _0.5 ) _0.2 } O _3-δ , Y _{2 is} used as oxide _2. 0.4 mass% Pd was added to a mixture in which O ₃ and NiO were added at a molar ratio of Y: Ni = 60: 40 so that the total amount of Y and La was 5 mol% with respect to Sr. A supported catalyst and a catalyst member using the catalyst were produced in the same manner as described above. Here, Nb ₂ O ₅ powder and NiO powder were used as raw materials for Nb and Ni. The mixture of Y ₂ O ₃ and NiO was preliminarily pulverized so that the average particle diameter D50 was 0.1 μm.

When the constituent phases of the fired mixture were evaluated by powder X-ray diffraction, a first phase similar to Sr {Fe _0.5 Ta _0.5 } O ₃ and a second similar to oxide 1 of Example 1 were obtained. From the oxide 1 consisting of two phases of the perovskite structure, Y ₂ O ₃ well matched with 41-1105 of ICDD's Powder Diffraction File, and NiO well matched with 44-1159 It became the mixed state of the oxide particle 2 which becomes. It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively. The specific surface area of the powdery catalyst after the heat test was 9 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were acceptable (Δ), the heat resistance was acceptable (Δ), and the overall judgment was Δ.

(Example 12)
In contrast to oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 {Fe _0.9 (Ta _0.7 Ti _0.3 ) _0.1 } O _3-δ , Y _{2 is} used as oxide _2. A mixture having a molar ratio of O ₃ and CeO ₂ of Y: Ce = 60: 40 was added to a mixture in which the total amount of Y and Ce was 15 mol% with respect to Sr. And a catalyst member were produced by the same method as described above. Here, anatase TiO ₂ and CeO ₂ powder were used as raw materials for Ti and Ce. Further, the mixture of Y ₂ O ₃ and CeO ₂ was preliminarily pulverized so that the average particle diameter D50 was 0.1 μm.

When the constituent phases of the fired mixture were evaluated by powder X-ray diffraction, a first phase similar to Sr {Fe _0.5 Ta _0.5 } O ₃ and a second similar to oxide 1 of Example 1 were obtained. Of the perovskite structure, Y ₂ O ₃ well matched with 41-1105 of ICDD's Powder Diffraction File, and CeO ₂ well matched with 34-394 It was in the mixed state of the oxide 2 which consists of. It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively. The specific surface area of the powdery catalyst after the heat test was 8 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were acceptable (Δ), the heat resistance was acceptable (Δ), and the overall judgment was Δ.

(Example 13)
In contrast to oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 {Fe _0.9 (Ta _0.7 Ti _0.3 ) _0.1 } O _3-δ , Y _{2 is} used as oxide _2. A mixture having a molar ratio of O ₃ and CeO ₂ of Y: Ce = 60: 40 was added to a mixture in which the total amount of Y and Ce was 15 mol% with respect to Sr. And a catalyst member were produced by the same method as described above. Here, the mixture of Y ₂ O ₃ and CeO ₂ was pre-ground so that the average particle diameter D50 was 0.1 μm.

When the constituent phases of the fired mixture were evaluated by powder X-ray diffraction, a first phase similar to Sr {Fe _0.5 Ta _0.5 } O ₃ and a second similar to oxide 1 of Example 1 were obtained. Of the perovskite structure, Y ₂ O ₃ well matched with 41-1105 of ICDD's Powder Diffraction File, and CeO ₂ well matched with 34-394 It was in the mixed state of the oxide 2 which consists of. It was 20 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Moreover, when the average particle diameter of the oxide 1 and the oxide 2 in this grinding | pulverization mixture was measured, they were 0.20 micrometer and 0.08 micrometer, respectively. The specific surface area of the powdery catalyst after the heat test was 7 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were acceptable (Δ), heat resistance was good (◯), and overall judgment was ○ −.

(Example 14)
In contrast to oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 {Fe _0.9 (Ta _0.7 Ti _0.3 ) _0.1 } O _3-δ , Y _{2 is} used as oxide _2. A mixture having a molar ratio of O ₃ and CeO ₂ of Y: Ce = 60: 40 was added to a mixture in which the total amount of Y and Ce was 15 mol% with respect to Sr. And a catalyst member were produced by the same method as described above. Here, the mixture of Y ₂ O ₃ and CeO ₂ was preliminarily pulverized so that the average particle diameter D50 was 0.3 μm.

When the constituent phases of the fired mixture were evaluated by powder X-ray diffraction, a first phase similar to Sr {Fe _0.5 Ta _0.5 } O ₃ and a second similar to oxide 1 of Example 1 were obtained. Of the perovskite structure, Y ₂ O ₃ well matched with 41-1105 of ICDD's Powder Diffraction File, and CeO ₂ well matched with 34-394 It was in the mixed state of the oxide 2 which consists of. It was 20 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Moreover, when the average particle diameter of the oxide 1 and the oxide 2 in this grinding | pulverization mixture was measured, they were 0.12 micrometer and 0.10 micrometer, respectively. The specific surface area of the powdery catalyst after the heat test was 7 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were acceptable (Δ), the heat resistance was acceptable (Δ), and the overall judgment was Δ.

(Example 15)
In contrast to the oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 Fe _1.0 O _3-δ , Y ₂ O ₃ , CeO ₂ and NiO as the oxide 2 are Y: Ce: Ni = 50. A catalyst in which 0.4 mass% of Pd is supported on a mixture in which a mixture having a molar ratio of 30:20 is added so that the total amount of Y, Ce, and Ni is 15 mol% with respect to Sr, And the catalyst member was manufactured by the method similar to the above using this. Here, the mixture of Y ₂ O ₃ , CeO ₂ and NiO was preliminarily pulverized so that the average particle diameter D50 was 0.1 μm.

The constituent phases of the fired mixture were evaluated by powder X-ray diffraction. As a result, the oxide 1 composed of a single phase having a perovskite structure and Y ₂ O ₃ , 34- It was in a mixed state of oxide 2 composed of CeO ₂ well matched with 394 and NiO well matched with 44-1159. It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively. The specific surface area of the powdery catalyst after the heat test was 9 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were acceptable (Δ), the heat resistance was acceptable (Δ), and the overall judgment was Δ.

(Example 16)
In contrast to the oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 Fe _1.0 O _3-δ , Y ₂ O ₃ and La ₂ O ₃ as the oxide 2 are Y: La = 60: A catalyst in which 0.4 mass% of Pd is supported on a mixture in which a mixture having a molar ratio of 40 is added so that the total amount of Y and La is 15 mol% with respect to Sr, and A catalyst member was produced in the same manner as described above. Here, the mixture of Y ₂ O ₃ and La ₂ O ₃ was preliminarily pulverized so that the average particle diameter D50 was 0.1 μm.

The constituent phases of the fired mixture were evaluated by powder X-ray diffractometry. As a result, the oxide 1 composed of a single phase having a perovskite structure, Y ₂ O ₃ well matched with 41-1105 of the Powder Diffraction File of ICDD, and 5 It was in a mixed state of oxide 2 made of La ₂ O ₃ that was in good agreement with -602. It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively. The specific surface area of the powdery catalyst after the heat test was 10 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 5. The purification characteristics were acceptable (Δ), the heat resistance was acceptable (Δ), and the overall judgment was Δ.

(Comparative Example 1)
With respect to the composite oxide composed only of oxide 1 having a perovskite crystal structure whose composition is represented by Ba _1.0 {Fe _0.75 Co _0.25 } O _3-δ , 0.4 mass% of Pd A supported catalyst and a catalyst member using the catalyst were produced in the same manner as described above.

When the constituent phases of the composite oxide particles were evaluated by a powder X-ray diffraction method, it was a single phase having a perovskite structure. It was 25 m < ² > / g when the specific surface area of the ground powder by a bead mill was measured. The average particle size of the composite oxide was measured and found to be 0.10 μm. On the other hand, the specific surface area of the powdery catalyst after the heat test was greatly reduced to 2 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 6. The purification characteristics were poor (x), the heat resistance was poor (x), and the comprehensive judgment was x. The purification performance of this catalyst is greatly deteriorated after the heat resistance test and is inferior to the catalyst of the present invention.

(Comparative Example 2)
In contrast to the oxide 1 having a perovskite crystal structure whose composition is represented by Sr _0.8 {Fe _0.65 Co _0.35 } O _3-δ , Y ₂ O ₃ and La ₂ O ₃ are used as the oxide 2. Catalyst in which 0.4 mass% of Pd is supported on a mixture in which a mixture having a molar ratio of Y: La = 60: 40 is added so that the total amount of Y and La is 5 mol% with respect to Sr. And the catalyst member was manufactured by the method similar to the above using this. Here, the mixture of Y ₂ O ₃ and La ₂ O ₃ was preliminarily pulverized so that the average particle diameter D50 was 0.1 μm.

The constituent phases of the fired mixture were evaluated by powder X-ray diffractometry. As a result, the oxide 1 composed of a single phase having a perovskite structure, Y ₂ O ₃ well matched with 41-1105 of the Powder Diffraction File of ICDD, and 5 It was in a mixed state of oxide 2 made of La ₂ O ₃ that was in good agreement with -602. It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively. On the other hand, the specific surface area of the powdered catalyst after the heat test was greatly reduced to 4 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 6. The purification characteristics were poor (x), the heat resistance was poor (x), and the comprehensive judgment was x. The purification performance of the catalyst is greatly deteriorated after the heat resistance test and is inferior to the catalyst of the present invention.

(Comparative Example 3)
In contrast to oxide 1 having a perovskite crystal structure whose composition is represented by {Sr _0.5 La _0.5 } _1.2 {Fe _0.7 Ta _0.3 } O _3-δ , Y _{2 is} used as oxide _2. 0.1 mass is added to a mixture in which O ₃ and La ₂ O ₃ are added at a molar ratio of Y: La = 60: 40 so that the total amount of Y and La is 30 mol% with respect to Sr. A catalyst comprising 1% Pd and a catalyst member using the same were produced in the same manner as described above. Here, the mixture of Y ₂ O ₃ and La ₂ O ₃ was preliminarily pulverized so that the average particle diameter D50 was 0.1 μm.

When the constituent phases of the fired mixture were evaluated by powder X-ray diffraction, a first phase similar to Sr {Fe _0.5 Ta _0.5 } O ₃ and a second similar to oxide 1 of Example 1 were obtained. The oxide 1 composed of two types of phases having a perovskite structure, Y ₂ O ₃ well matched with 41-1105 of ICDD's Powder Diffraction File, and La ₂ well matched with 5-602 It was a mixed state of oxide 2 made of O ₃ . It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively.

  Furthermore, when the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, the purification characteristics were low. The evaluation results are shown in Table 6. The purification characteristics were poor (x), the heat resistance was poor (x), and the comprehensive judgment was x. The purification performance of the catalyst is already very low in initial characteristics and inferior to the catalyst of the present invention.

(Comparative Example 4)
In contrast to the oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 Fe _1.0 O _3-δ , Y ₂ O ₃ and La ₂ O ₃ as the oxide 2 are Y: La = 60: A catalyst in which 0.4 mass% of Pd is supported on a mixture in which a mixture having a molar ratio of 40 is added so that the total amount of Y and La is 40 mol% with respect to Sr, and A catalyst member was produced in the same manner as described above. Here, the mixture of Y ₂ O ₃ and La ₂ O ₃ was preliminarily pulverized so that the average particle diameter D50 was 0.1 μm.

The constituent phases of the fired mixture were evaluated by powder X-ray diffractometry. As a result, the oxide 1 composed of a single phase having a perovskite structure, Y ₂ O ₃ well matched with 41-1105 of the Powder Diffraction File of ICDD, and 5 It was in a mixed state of oxide 2 made of La ₂ O ₃ that was in good agreement with -602. It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.10 μm and 0.05 μm, respectively.

  Furthermore, when the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, the purification characteristics were low. The evaluation results are shown in Table 6. The purification characteristics were poor (x), the heat resistance was poor (x), and the comprehensive judgment was x. The purification performance of the catalyst is already very low in initial characteristics and inferior to the catalyst of the present invention.

(Comparative Example 5)
In contrast to the oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 Fe _1.0 O _3-δ , Y ₂ O ₃ and La ₂ O ₃ as the oxide 2 are Y: La = 60: A catalyst in which 0.4 mass% of Pd is supported on a mixture in which a mixture having a molar ratio of 40 is added so that the total amount of Y and La is 2 mol% with respect to Sr, and A catalyst member was produced in the same manner as described above. Here, the mixture of Y ₂ O ₃ and La ₂ O ₃ was preliminarily pulverized so that the average particle diameter D50 was 0.5 μm.

The constituent phases of the fired mixture were evaluated by powder X-ray diffractometry. As a result, the oxide 1 composed of a single phase having a perovskite structure, Y ₂ O ₃ well matched with 41-1105 of the Powder Diffraction File of ICDD, and 5 It was in a mixed state of oxide 2 made of La ₂ O ₃ that was in good agreement with -602. When the specific surface area of the pulverized baked mixture (pulverized mixture) was measured after pulverization with a bead mill was completed in a shorter time than usual, it was 15 m ² / g, which was a value lower than that of Claim 6. Further, when the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.25 μm and 0.3 μm, respectively, which were outside the scope of the present invention. On the other hand, the specific surface area of the powdery catalyst after the heat test was greatly reduced to 2 m ² / g.

  Further, after the catalyst is supported on a honeycomb-shaped metal carrier and the catalyst performance is evaluated, the heat resistance test is performed on the honeycomb-shaped carrier, and the evaluation result of evaluating the catalyst performance again is shown in Table 6. The purification characteristics were poor (x), the heat resistance was poor (x), and the comprehensive judgment was x. The purification performance of this catalyst is greatly deteriorated after the heat resistance test and is inferior to the catalyst of the present invention.

(Comparative Example 6)
In contrast to the oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 Fe _1.0 O _3-δ , Y ₂ O ₃ and La ₂ O ₃ as the oxide 2 are Y: La = 60: A mixture having a molar ratio of 40 added so that the total amount of Y and La was 4 mol% with respect to Sr was produced in the same manner as described above. Here, the mixture of Y ₂ O ₃ and La ₂ O ₃ was preliminarily pulverized so that the average particle diameter D50 was 0.1 μm. In the production of this catalyst, the first firing is performed in an electric furnace at 900 ° C. for 5 hours in the atmosphere, the fired product is crushed and then dry pulverized in an automatic mortar, and the second firing is performed in an electric furnace. It was carried out for 5 hours at 1400 ° C. in the atmosphere and at a temperature higher than the range of claim 6.

The constituent phases of the fired mixture were evaluated by powder X-ray diffractometry. As a result, the oxide 1 composed of a single phase having a perovskite structure, Y ₂ O ₃ well matched with 41-1105 of the Powder Diffraction File of ICDD, and 5 It was in a mixed state of oxide 2 made of La ₂ O ₃ that was in good agreement with -602. Subsequently, the calcined mixture was pulverized by a bead mill, but the specific surface area of the pulverized calcined mixture (pulverized mixture) did not reach 20 m ² / g, and the catalyst of the present invention could not be produced.

  The evaluation results of this catalyst are shown in Table 6. The purification characteristics were poor (x), the heat resistance was poor (x), and the comprehensive judgment was x.

(Comparative Example 7)
In contrast to the oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 Fe _1.0 O _3-δ , Y ₂ O ₃ and La ₂ O ₃ as the oxide 2 are Y: La = 60: A catalyst in which 0.4 mass% of Pd is supported on a mixture in which a mixture having a molar ratio of 40 is added so that the total amount of Y and La is 40 mol% with respect to Sr, and A catalyst member was produced in the same manner as described above. Here, the mixture of Y ₂ O ₃ and La ₂ O ₃ was preliminarily pulverized so that the average particle diameter D50 was 0.1 μm. Further, in the production of the present catalyst, the firing was performed only once in 5 hours in the electric furnace at 800 ° C. in the atmosphere at a temperature lower than the range of claim 6.

When the constituent phase of the fired mixture was analyzed by powder X-ray diffraction, it was found that the raw material of oxide 1 remained almost unreacted and a phase having a perovskite structure was not formed. It was 25 m < ² > / g when the specific surface area of the baking mixture (crushed mixture) grind | pulverized by the bead mill was measured. When the average particle size in the pulverized mixture was measured, the oxide 1 could not be evaluated because no perovskite structure was formed. On the other hand, the average particle size of the oxide 2 was 0.05 μm.

  Furthermore, when the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, the purification characteristics were low. The evaluation results are shown in Table 6. The purification characteristics were poor (x), the heat resistance was poor (x), and the comprehensive judgment was x. The purification performance of the catalyst is already very low in initial characteristics and inferior to the catalyst of the present invention.

(Example 17)
In contrast to the oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 Fe _1.0 O _3-δ , Y ₂ O ₃ and La ₂ O ₃ as the oxide 2 are Y: La = 60: A catalyst in which 0.4 mass% of Pd is supported on a mixture in which a mixture having a molar ratio of 40 is added so that the total amount of Y and La is 15 mol% with respect to Sr, and Catalyst members were manufactured and the catalyst performance was evaluated.

  First, oxide 1 was produced by the following method.

Granular SrCO ₃ and Fe ₂ O ₃ were used as raw materials for Sr and Fe, respectively. The raw materials are weighed so that the molar ratio is Sr: Fe = 1.0: 1.0, added to ethyl alcohol (dispersion medium), and wet-mixed while pulverizing with a ball mill to obtain a slurry. It was. The rotary evaporator solids were separated from the slurry and dried at approximately 120 ° C. for 1 hour. Next, the obtained dried product was crushed, put into a corner or container made of MgO ceramic, and baked in an electric furnace at 900 ° C. for 5 hours in the air to obtain a porous massive fired product. After the fired product was crushed, it was dry-pulverized with an automatic mortar, placed again in a corner or container made of MgO ceramic, and fired in an electric furnace at 1100 ° C. for 5 hours in the atmosphere. When the constituent phase was evaluated by a powder X-ray diffraction method, it was a single phase of oxide 1 having a perovskite structure. The powder was pre-ground and adjusted to an average particle size of 0.2 μm.

Further, Y ₂ O ₃ as oxide 2 and a powdery mixture of La ₂ O _{3 in} a molar ratio of Y: La = 60: 40 are preliminarily pulverized so that the average particle diameter D50 is 0.1 μm. went.

The oxide 1 and the oxide 2 are weighed and mixed so that the total amount of Y and La of the oxide 2 is 15 mol% with respect to Sr of the oxide 1, and the same method as above. Then, the added mixture was pulverized in a bead mill using ethanol as a solvent for 3 hours. It was 25 m < ² > / g when the specific surface area of the obtained ground mixture was measured. The average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured and found to be 0.1 μm and 0.05 μm, respectively. Next, 0.4 mass% Pd was supported on the pulverized mixture by the same method as described above. Furthermore, when the heat resistance test was performed in the same manner as described above, the specific surface area of the powdered catalyst after the heat resistance test was 13 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 6. The purification characteristics were acceptable (Δ), the heat resistance was acceptable (Δ), and the overall judgment was Δ.

(Example 18)
In contrast to the oxide 1 having a perovskite crystal structure whose composition is represented by Sr _1.0 Fe _1.0 O _3-δ , Y ₂ O ₃ and La ₂ O ₃ as the oxide 2 are Y: La = 60: A catalyst in which 0.4 mass% of Pd is supported on a mixture in which a mixture having a molar ratio of 40 is added so that the total amount of Y and La is 15 mol% with respect to Sr, and A catalyst member was produced in the same manner as described above, and the catalyst performance was evaluated.

In this catalyst, the average particle diameters of oxide 1 and oxide 2 before grinding with bead mill were adjusted to 1.0 μm and 0.5 μm, respectively. It was 20 m < ² > / g when the specific surface area of the obtained ground mixture was measured. Moreover, when the average particle diameter of the oxide 1 and the oxide 2 in this grinding | pulverization mixture was measured, they were 0.2 micrometer and 0.1 micrometer, respectively. Moreover, the specific surface area of the powdery catalyst after the heat test was 10 m ² / g.

  Furthermore, after the catalyst was supported on a honeycomb-shaped metal carrier and the catalyst performance was evaluated, a heat resistance test was performed on the honeycomb-shaped carrier, and the catalyst performance was evaluated again. The evaluation results are shown in Table 6. The purification characteristics were acceptable (Δ), the heat resistance was acceptable (Δ), and the overall judgment was Δ.

(Comparative Example 8)
With respect to the oxide 1 having a perovskite type crystal structure whose composition is represented by Sr _1.0 Fe _0.65 Co _0.35 O _3-δ , Y ₂ O ₃ and La ₂ O ₃ as the oxide 2 are Y: A catalyst in which 0.4 mass% of Pd is supported on a mixture in which a mixture having a molar ratio of La = 60: 40 is added so that the total amount of Y and La is 15 mol% with respect to Sr; and Using this, a catalyst member was produced in the same manner as described above, and the catalyst performance was further evaluated.

In the present catalyst, the average particle diameters of oxide 1 and oxide 2 before bead milling were adjusted to 0.2 μm and 1.0 μm, respectively. Here, the particle size of the oxide 2 is outside the range of claim 7. Then, it grind | pulverized until the specific surface area of the grind | pulverized mixture by a bead mill became 30 m < ² > / g. When the average particle diameters of oxide 1 and oxide 2 in the pulverized mixture were measured, they were 0.05 μm and 0.1 μm, respectively, and the average particle diameter of oxide 1 was smaller than that of oxide 2 This is outside the scope of the present invention of claim 1. The specific surface area of the catalyst after the heat test was greatly reduced to 3 m ² / g. The evaluation results are shown in Table 4. The purification characteristics were poor (x), the heat resistance was poor (x), and the comprehensive judgment was x.

  From the results of the above Examples and Comparative Examples, the Examples of the present invention were all excellent in the decomposition of CO, HC and NOx gases, and all of them were excellent in heat resistance in the evaluation of heat resistance.

  On the other hand, Comparative Examples 1 and 2 are complex oxides that do not satisfy the composition range defined in claim 1, which is a requirement of the present invention, and the purification characteristics and heat resistance of the catalyst are insufficient. Further, both Comparative Examples 3 and 4 are complex oxides that do not satisfy the composition range defined in claim 1 and have insufficient purification characteristics and heat resistance. On the other hand, Comparative Example 5 is a composite oxide that does not satisfy the composition range defined in claim 1, and the specific surface area after the heat treatment is outside the range of claim 6, and the purification characteristics and heat resistance are insufficient. is there. In Comparative Example 6, the composition range of Claim 1 is not satisfied, and the firing is performed at a higher temperature than the range of Claim 6, so that it is difficult to synthesize the catalyst. Since Comparative Example 7 does not satisfy the composition range of claim 1 and is fired at a temperature lower than that of claim 6, the perovskite phase formation reaction does not proceed sufficiently, and purification characteristics and heat resistance Insufficient sex. In Comparative Example 8, the composition range of Claim 1 is not satisfied, and the particle size of the raw material of oxide 2 is outside the range of Claim 7, and the purification characteristics and heat resistance are insufficient.

The composition of oxide 1 is shown in Table 2; the conditions of oxide 2, the catalyst conditions and physical properties are shown in Tables 3 and 4; and the results of catalyst performance evaluation are shown in Tables 5 and 6. Examples 1 to 16 and Comparative Examples 1 to 7 are catalysts manufactured by the first manufacturing method. Examples 17 to 18 and Comparative Example 8 are catalysts produced by the second production method.

Claims (9)

From the oxide 1 having a phase of perovskite structure and having an average particle size of 0.2 μm or less represented by the following (formula 1), Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ , NiO to Y ₂ A mixture of at least one selected from O ₃ and an oxide 2 having an average particle size of 0.1 μm or less;
A1 _a1 {Fe _(1-b1-c1) B1 _b1 C1 _c1 } O _3-δ (Formula 1)
(Where A1 is one or two elements selected from Ba, Sr and Ca,
B1 and C1 may not arrange elements,
In the case of arranging B1, one or two elements selected from Co and Cu,
In the case where C1 is arranged, one or more elements selected from Ti, Nb, Ta and including Ta or Nb,
1.0 ≦ a1 ≦ 1.1, 0 ≦ b1 ≦ 0.25, 0 ≦ c1 ≦ 0.2,
δ is a value determined by the history of the material and satisfies 0 ≦ δ <3)
Comprising at least one noble metal selected from Pd, Pt and Rh supported on a mixture of oxide 1 and oxide 2;
The average particle size of the oxide 2 is smaller than the average particle size of the oxide 1,
The exhaust gas purifying catalyst, wherein the total amount of Y, La, Ce, and Ni in the oxide 2 is 5 mol% or more and 30 mol% or less with respect to A1 of the oxide 1. The oxide 1 having a perovskite structure phase as the oxide 1 and having an average particle size of 0.2 μm or less and the composition represented by the following (formula 2), and the oxide 2 having an average particle size of 0.1 μm or less A mixture with Y ₂ O _{3 being}
The exhaust gas-purifying catalyst according to claim 1, wherein the amount of Y in Y ₂ O ₃ is 5 mol% or more and 25 mol% or less with respect to A2 of the oxide 1 '.
A2 _a2 {Fe _(1-b2-c2) Cu _b2 C2 _c2 } O _3-δ (Formula 2)
(Where A2 is one or two elements selected from Sr and Ca,
Cu and C2 may not be arranged,
When there is an element to be arranged in C2, one or more elements selected from Ti, Nb, Ta to Ta or Nb are necessarily included,
1.0 ≦ a2 ≦ 1.05, 0 ≦ b2 ≦ 0.2, 0 ≦ c2 ≦ 0.2,
δ is a value determined by the history of the material and satisfies 0 ≦ δ <3) The oxide 1 ″ having a perovskite structure phase as the oxide 1 and an average particle size of 0.2 μm or less is represented by the following (formula 3), and the oxide 2 has an average particle size of 0. Including a mixture with Y ₂ O ₃ which is 1 μm or less,
The exhaust gas-purifying catalyst according to claim 1 or 2, wherein the amount of Y in Y ₂ O ₃ is 5 mol% or more and 15 mol% or less with respect to A3 of oxide 1 ''.
A3 _a3 {Fe _(1-b3-c3) Cu _b3 Ta _c3 } O _3-δ (Formula 3)
(Where A3 is one or two elements selected from Sr and Ca,
In some cases, Cu is not contained.
1.0 ≦ a3 ≦ 1.05, 0 ≦ b3 ≦ 0.2, 0.1 ≦ c3 ≦ 0.2,
δ is a value determined by the history of the material and satisfies 0 ≦ δ <3) The oxide 1 having a perovskite structure phase as the oxide 1 and having an average particle size of 0.2 μm or less and the composition represented by the following (formula 4), and the oxide 2 having an average particle size of 0 A mixture with Y ₂ O ₃ that is 1 μm or less,
The exhaust gas-purifying catalyst according to any one of claims 1 to ₃ , wherein the amount of Y in Y ₂ O ₃ is 10 mol% or more and 20 mol% or less with respect to Sr of the oxide 1 '''.
Sr _a4 {Fe _(1-b4) Cu _b4 } O _3-δ (Formula 4)
(Cu may not be included,
Where 1.0 ≦ a4 ≦ 1.05, 0 ≦ b4 ≦ 0.2,
δ is a value determined by the history of the material and satisfies 0 ≦ δ <3) The exhaust gas purifying catalyst according to any one of claims 1 to 4, wherein the exhaust gas purifying catalyst has a specific surface area of at least 7 m ² / g after heat treatment at 900 ° C for 5 hours in the atmosphere. A method for producing the exhaust gas-purifying catalyst according to any one of claims 1 to 5,
One or more carbonate or hydroxide powders selected from carbonates and hydroxides of alkaline earth metal elements of oxide 1, oxide 1 ′, oxide 1 ″ or oxide 1 ′ ″ , Oxide 1, oxide 1 ′, oxide 1 ″ or oxide 1 ′ ″, oxide powders of constituent elements other than alkaline earth elements, and the average grain size of oxide constituting oxide 2 After firing a mixture with a powder having a diameter of 0.5 μm or less at a plurality of temperatures selected from 900 ° C. or more and 1200 ° C. or less to obtain a firing mixture of oxide 1 and oxide 2,
A method for producing an exhaust gas purifying catalyst, wherein the fired mixture is pulverized by pulverization using ceramic balls until the specific surface area becomes at least 20 m ² / g. A method for producing the exhaust gas-purifying catalyst according to any one of claims 1 to 5,
One or more carbonate or hydroxide powders selected from carbonates and hydroxides of alkaline earth metal elements of oxide 1, oxide 1 ′, oxide 1 ″ or oxide 1 ′ ″ , Oxide 1, oxide 1 ′, oxide 1 ″ or oxide 1 ′ ″ and a mixture of oxides of constituent elements other than alkaline earth elements are selected from 900 ° C. to 1200 ° C. After obtaining a phase of perovskite structure by firing at multiple temperatures,
Add and mix the powder of the oxide constituting the oxide 2 with an average particle size of 0.5 μm or less,
A method for producing an exhaust gas purification catalyst, wherein the additive mixture is pulverized by pulverization using ceramic balls until the specific surface area becomes at least 20 m ² / g.   8. The method for producing an exhaust gas purifying catalyst according to claim 6, wherein at least one precious metal selected from Pd, Pt, and Rh is supported on the pulverized fired mixture or the pulverized additive mixture. 9. An exhaust gas purification catalyst member comprising the base material carrying the exhaust gas purification catalyst according to any one of claims 1 to 5.