JPH0986928A - A-site deficient perovskite double oxide and catalyst composed thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an A-side deficient perovskite double oxide and a catalyst containing the oxide utilizable as a catalyst for cleaning the gas exhausted from an internal combustion engine of automobile, etc., a catalyst for the combustion of natural gas, etc., or the adsorption and cleaning of harmful substances such as nitrogen oxides and usable also as an electrode material of a sensor or a fuel cell. SOLUTION: The objective double oxide has a perovskite structure expressed by the general formula A1-α BO3-δ (A is at least one kind of element selected from alkali metal elements, alkaline earth metal elements, rare earth elements, Y, Bi and Pb; B is a 3d transition metal element and/or Al) wherein the compositional ratio of the B-site element to the A-site element (B-A)/B}=αis >0, the allowable range for α is 0<α<0.2 and that of δ is 0<=δ<=1.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an A-site deficient perovskite composite oxide and a catalyst using the same.
In particular, it can be used for exhaust gas purification catalysts discharged from internal combustion engines such as automobiles, combustion catalysts for natural gas, etc. or for adsorbing and purifying harmful substances such as nitrogen oxides, and further for electrode materials for sensors and fuel cells. The present invention also relates to an A-site deficient perovskite composite oxide having a catalytic action which can also be used as a catalyst and a catalyst using the same.

[0002]

2. Description of the Related Art Conventionally, as a catalyst for purifying exhaust gas from an internal combustion engine of an automobile or the like, a catalyst in which a precious metal such as platinum, rhodium and palladium is supported on a carrier substrate such as alumina has been mainly used. In particular, rhodium has been used as an essential component for purifying NO _x , but it is an expensive catalyst material because of its lack of resources.

[0003] Further, due to the recent increasing awareness of the environment on a global scale, the required level of purification of exhaust gas is increasing in terms of mass. Under such circumstances, there is concern that the demand for precious metals will expand, and supply shortages will result in further cost increases. Due to these problems, application of palladium to exhaust gas purifying catalyst, which is relatively abundant as a resource and inexpensive, has been attempted.

It is generally known that when palladium is used as a catalyst component, the palladium oxide is reduced in a high temperature range and the NO _x purification ability of the palladium catalyst cannot be sufficiently obtained. It has been confirmed so far that selecting a perovskite composition and adding it as a co-catalyst is effective for the purpose of improving the NO _x purification performance of this palladium (Japanese Patent Application No. 5-292023).

However, when perovskite is used as a catalyst or a co-catalyst and alumina is used as a base material to form a catalyst carrier, the perovskite and alumina react with each other by being used for a long time in a high temperature range, and the perovskite is reacted. It causes a decrease in the specific surface area and a deterioration in the catalyst performance. Further, even when trying to improve the catalytic activity by supporting the perovskite on the surface of the zirconia-based base material in a highly dispersed manner, although the deterioration is less than that of alumina, the supported perovskite component and zirconia In some cases, a solid phase reaction occurs in a high temperature region, and a sufficient dispersion effect cannot be obtained (N. Mizuno et al.
al. : J. Am. Chem. Soc. Vol. 11
4, 7151 (1992)).

Further, in the perovskite containing Co as a main component, the structure is decomposed in a reducing atmosphere at a high temperature, or strontium is contained in the perovskite composition in order to improve the catalytic activity by controlling the valence. It is pointed out that this strontium reacts with palladium, which is a catalyst component, at high temperature and is deactivated (Tanaka, Takahashi: Automotive Technology, Vol.47, p51 (1).
993)).

As a method of improving durability by suppressing the characteristic deterioration of the perovskite catalyst containing Co as a main component in a high temperature region, the content of Fe, which is effective in improving the reduction resistance, is increased. , Strontium instead of cerium as a substituting element, for example, La
Durability by using _0.9 Ce _0.1 Co _0.4 Fe _0.6 O _{3 −} δ as a catalyst component and using a (Ce, Zr, Y) O ₂ base material that does not easily react with perovskite to suppress solid-phase reaction It has been attempted to achieve both good and catalytic activity (Tanaka, Takahashi: Automotive Technology, Vol.47,
p51 (1993)).

However, when a perovskite composition containing a large amount of Fe is used for the purpose of improving heat resistance, it becomes difficult to obtain sufficient catalytic activity even in a low temperature region of exhaust gas, resulting in an increase in the amount of noble metal components. In addition, select the composition of the base material and improve the durability so that it will not cause characteristic deterioration under more severe conditions and will respond to the tightening of exhaust gas regulations in North America and Europe and the exhaust gas regulations that are expected to become stricter in the future. In this case, the current perovskite composition naturally causes a limit in the usage environment.

Further, since the characteristics of elements such as strontium and cerium appear in the catalytic activity depending on each constituent,
Even when attempting to construct a catalyst by making use of such characteristics of catalytic activity in perovskites, the interaction between the constituent components and the precious metal catalyst is suppressed as much as possible in order to suppress the deterioration of the catalytic action on the precious metal due to the constituent elements. Will be required. Further, it is important to design a catalyst material that effectively controls the valence by utilizing the activity of the perovskite itself and improves the catalytic activity and durability of the perovskite itself.

Perovskite is also used as an electrode material for fuel cells and sensors, and has been attracting attention as an electrode material for stabilized zirconia and ceria-based oxygen ion conductors. The complex oxide having the perovskite structure is a mixed ionic conductor having low specific resistance and high oxygen ion conductivity. In particular, it is known that a material containing a 3d transition metal such as Co or Mn is cheaper than a platinum electrode, and can be operated at a low temperature when used as an electrode material of an oxygen sensor (Y. Takeda, R .;
Kanno, M .; Noda, Y. Tomida, and
O. Yamamoto, J. Electroche
m. Soc. , 134, 11, 2656 (198
7)).

[0011]

Thus, the perovskite particularly utilizes its catalytic function as an electrode material for fuel cells and sensors. At this time, the oxygen ion conductor, that is, the solid electrolyte and the electrode material, is used. It is necessary to suppress the characteristic deterioration and peeling due to the chemical reaction at the solid electrolyte / electrode material interface while ensuring the adhesiveness between them.

Therefore, an object of the present invention is to suppress a solid-state reaction between a perovskite and an oxide in contact with the perovskite by using an A-site deficient perovskite composite oxide having a predetermined composition ratio and to have a catalytic action. -Type composite oxides improve the durability and heat resistance, and effectively control the valences that make an important contribution to the catalytic action, and the oxygen vacancies introduced by the valence control move rapidly into the crystal lattice. (EN) Provided are an A-site deficient perovskite composite oxide and a catalyst using the same.

[0013]

Means for Solving the Problems The inventors of the present invention have made extensive studies to solve the above problems, and as a means for solving the problems, the composition ratio of the B site element to the A site element in the perovskite structure {(B−A ) / B} ratio = α is 0
In a larger composite oxide represented by the general formula A _1- αBO ₃ -δ, the range of α is 0 <α <0.2, preferably 0.1 <α <0.15, and , Δ can be in the range of 0 ≦ δ ≦ 1, by using the A-site deficient perovskite composite oxide, the solid-state reaction between the perovskite and the oxide in contact with the solid phase reaction is suppressed, and the catalytic action Of the perovskite-type complex oxides with the properties of valence control, which improves the durability and heat resistance of the perovskite-type composite oxide, and effectively activates the valence control that makes an important contribution to the catalytic action. The movement of oxygen vacancies introduced by the method within the crystal lattice changes depending on the amount of A-site deficiency, and the release and absorption characteristics of oxygen, which is important for the catalytic action of redox, is 0 <α <0.2, preferably 0.1 <α <0.15 The present invention has been achieved by discovering that it effectively works in. If α is larger than 0.2, the second
This is not preferable because the amount of phase precipitation increases and the oxygen release and absorption characteristics deteriorate, and especially when it exceeds 0.15, the second phase precipitates, and the perovskite structure tends to become unstable.
It is particularly preferable that 0.1 <α <0.15 because the oxygen releasing ability is improved.

The above-mentioned object of the present invention is that in the perovskite structure, the composition ratio of the B-site element to the A-site element {(BA) / B} ratio = α is larger than 0, and the general formula A _1- αBO _3- δ (A in the formula is composed of at least one selected from the group consisting of alkali metal elements, alkaline earth elements, rare earth elements, Y, Bi and Pb, and B is 3
In the A-site deficient perovskite composite oxide represented by (d transition metal element and / or Al), the range of α is 0 <α <0.2, and
This is achieved by the A-site deficient perovskite composite oxide characterized in that the possible range of δ is 0 ≦ δ ≦ 1.

Further, the above-mentioned object of the present invention is that in the perovskite structure, the composition ratio of the B-site element to the A-site element {(BA) / B} ratio = α is larger than 0,
The general formula A _1- αBO ₃ -δ (A in the formula is composed of at least one selected from the group consisting of alkali metal elements, alkaline earth elements, rare earth elements, Y and Pb, and B is
3 d of Ti, Mn, Fe, Co, Ni, and at least one selected from the group consisting of Cu and Al) in the A-site deficient perovskite complex oxide. This is achieved by an A-site deficient perovskite complex oxide characterized in that the obtained range is 0 <α <0.2 and the possible range of δ is 0 ≦ δ ≦ 1. δ is set to 0 ≦ δ ≦ 1 because the perovskite structure is most stable within such a range.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The A-site deficient perovskite composite oxide according to claim 1 of the present invention has a generally known perovskite ABO ₃ δ structure as a basic structure, and B for an A-site element. The composition ratio of site elements {(B−A) / B} ratio = α is greater than 0, and the general formula A ₁₋
αBO _{3 −} δ (A in the formula is composed of at least one selected from the group consisting of alkali metal elements, alkaline earth elements, rare earth elements, Y, Bi and Pb, and B is a 3d transition metal element and / or Or composed of Al)
By using the site-defective perovskite composite oxide, it is possible to suppress the solid-phase reaction between the perovskite and the oxide in contact with the perovskite, and to improve heat resistance and durability, as compared with the usual perovskite ABO _3- δ structure. it can.

Particularly, when the range of α in the general formula A _1- αBO ₃ -δ is 0 <α <0.2, the perovskite structure is stabilized and the atoms due to the A-site deficiency are formed. By controlling the valence, the introduction of oxygen vacancies, which plays an important role in the catalytic action, is promoted, and the range in which the amount of oxygen vacancies δ can be 0 ≦ δ ≦ 1 ensures the ability to absorb and release oxygen. The improvement of durability is realized.

The A-site deficient perovskite composite oxide according to claim 2 of the present invention is represented by the general formula A _1-
In the A-site deficient perovskite composite oxide represented by αBO ₃ −δ, the range of α is 0 <α <0.2.
And the possible range of δ is 0 ≦ δ ≦ 1,
Among rare earth metals, alkali metals and alkaline earth metals, A is La, Pr, Ce, Nd, Gd, Er, Y, B.
i, Ba, Sr, Ca, K and Pb, and at least one selected from the group consisting of 3d transition metal elements, B, Ti, Mn, Fe, Co, Ni, Cu and A.
Improving heat resistance and durability by forming an A-site deficient perovskite composite oxide from at least one constituent element selected from the group consisting of 1 and considered to have excellent heat resistance. You can

The A-site deficient perovskite complex oxide according to claim 3 of the present invention is the general formula A _1-
In the A-site deficient perovskite complex oxide represented by αBO _{3 −} δ, in the formula, A is A ′ and A ″, and B is a general formula (A ′ ₁₎ composed of two kinds of constituent elements, B ′ and B ″. _-x A ″
_x ) _1- α (B ′ _1-y B ″ _y ) O ₃₋ δ, wherein A ′ is composed of at least one selected from the group consisting of La, Nd, Gd, Y and Bi. A ″ is Pr, C
e, Ba, Sr, Ca, K and Pb, and at least one selected from the group consisting of
n, Co, Ti, Fe, Ni, Cu, and at least one selected from the group consisting of Al, and α,
The possible ranges of δ, x, and y are 0 <α <0.2,
By satisfying 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, and 0 ≦ y ≦ 1, it is possible to control the electronic state of the B site by controlling the valence, particularly by changing x, and thus the A site deficient perovskite. By configuring the structure, it is possible to improve the ability to release and absorb oxygen, and also improve heat resistance and durability.

The A site deficient perovskite composite oxide catalyst according to claim 4 of the present invention is the A ₁ -δ according to claim 3.
In the A-site deficient perovskite composite oxide represented by BO _3- α, A in the formula is A ′ and A ″, and B is B ′ and B ″.
A general formula (A ' _1-x A ″ _x ) consisting of two constituent elements of
_1- α (B ' _1-y B ″ _y ) O _3- δ (A ′ in the formula is La, N
d ', Gd and Y are composed of at least one selected from the group consisting of, A "is composed of at least one selected from the group consisting of Pr, Ce, Ba, Sr, Ca and K, and B'is B ″ is Mn, Co, Ti, Fe, Ni, C
u and Al), and the range of α, δ, x, y is 0 <α <0.2, 0 ≦ δ ≦ 1, 0 ≦ x ≦
When 1 and 0 ≦ y ≦ 1, the electronic state of the B site is controlled by controlling the valence by changing the x and y of the combination of elements effective for the catalytic activity, and the A site deficient perovskite is controlled. By constructing the structure, it is possible to improve the catalytic activity and also improve the heat resistance and durability.

The A-site deficient perovskite composite oxide catalyst according to claim 5 of the present invention is the general formula (A ′ _1-x A ″ _x ) _1- α ((B ′ _1-y B ″ _Y ) O _3- δ, where A ′ is composed of the group consisting of La, Nd, Gd and Y, and A ″ is Ce, Pr, Ba, Sr, Ca.
And K, B ′ is Co,
B ″ is composed of the group consisting of Mn, Fe, Ni and Al, and the range of α, δ, x, y is 0 respectively.
<Α <0.2, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, and 0 ≦ y ≦ 1 so that the catalytic activity of Co is effectively used and x and y are changed to control the valence. By controlling the electronic state of the B-site by doing so and forming an A-site deficient perovskite structure, the catalytic activity of Co can be maintained and heat resistance and durability can be improved.

The A site deficient perovskite composite oxide catalyst according to claim 6 of the present invention is the general formula (A ′ _1-x A ″ _x ) _1- α (B ′ _1-y B ″) according to claim 4. _y ) is represented by O _{3 −} δ, wherein A ′ is composed of the group consisting of La, Nd, Gd and Y, and A ″ is composed of the group consisting of Ce, Pr, Ba, Sr, Ca and K. , B ′ is Mn, and B ″
Is composed of the group consisting of Fe, Ti and Cu, and
The possible ranges of α, δ, x, and y are 0 <α <0.
2, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, and 0 ≦ y ≦ 1, so that the catalytic activity of Mn is effectively utilized, and the valence is controlled by changing x and y. It is possible to maintain the characteristics of the catalytic activity of Mn and improve the heat resistance and durability by controlling the electronic state of (1) and forming an A site deficient perovskite structure.

The A-site deficient perovskite composite oxide catalyst according to claim 7 of the present invention is the general formula (A ′ _1-x A ″ _x ) _1- α (B ′ _1-y B ″) according to claim 4. _y ) is represented by O _{3 −} δ, and the range of α, δ, x, y is 0 respectively.
<Α <0.2, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, at least Pd is supported as a noble metal on the A-site deficient perovskite composite oxide, and P
Stabilize elements that are thought to adversely affect d,
By suppressing the interaction with Pd, at least P
The heat resistance and durability of the complex oxide catalyst containing d can be improved.

The A-site deficient perovskite complex oxide catalyst according to claim 8 of the present invention is the general formula (A ′ _1-x A ″ _x ) _1- α (Co _1-y B ″ _y ) according to claim 7. ) Represented by O ₃ −δ, wherein A ′ is composed of the group consisting of La, Nd, Gd and Y, A ″ is composed of the group consisting of Ce, Pr, Ba, Sr, Ca and K, B ″ is Mn, Fe, Ni
And Al, and α, δ, x,
The possible ranges of y are 0 <α <0.2 and 0 ≦ δ ≦, respectively.
A, characterized in that 1, 0 ≦ x ≦ 1, 0 <y ≦ 1
At least Pd is supported as a noble metal on the site-defective perovskite complex oxide, and the complex oxide catalyst containing at least Pd is provided by stabilizing the element that is thought to adversely affect Pd and suppressing the interaction with Pd. It is possible to provide an excellent three-way catalyst for exhaust gas purification while improving the durability of the catalyst and utilizing the catalytic activity of Co.

The A-site deficient perovskite composite oxide catalyst according to claim 9 of the present invention is the general formula (A ′ _1-x A ″ _x ) _1- α (Mn _1-y B ″ _y ) according to claim 7. ) Represented by O ₃ −δ, wherein A ′ is composed of the group consisting of La, Nd, Gd and Y, A ″ is composed of the group consisting of Ce, Pr, Ba, Sr, Ca and K, B ″ is Fe and / or T
i, and the possible ranges of α, δ, x, y are 0 <α <0.2, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1,
At least Pd is supported as a noble metal on the A-site deficient perovskite composite oxide, which is characterized in that 0 ≦ y ≦ 1, and stabilizes an element that is considered to adversely affect Pd and interacts with Pd. By suppressing
It is possible to provide a three-way catalyst for exhaust gas purification that improves the heat resistance and durability of a complex oxide catalyst containing at least Pd and makes the most of the catalytic activity of Mn.

The A-site deficient perovskite complex oxide according to claim 10 of the present invention has a generally known perovskite ABO _3- δ structure as a basic structure, and
Composition ratio of B site element to site element {(B-
A) / B} ratio = α is larger than 0, and the general formula A _1- αBO _3-
In the A-site deficient perovskite composite oxide represented by δ, A in the formula is composed of at least one selected from the group consisting of alkali metal elements, alkaline earth elements, rare earth elements, Y and Pb, and B is The perovskite is composed of at least one selected from the group consisting of Ti, Mn, Fe, Co, Ni, Cu, and Al selected from the 3d transition metal elements, so that it has a perovskite structure more than that of a normal perovskite ABO _3- δ structure. It is possible to suppress the solid phase reaction with the oxide in contact with and to improve heat resistance and durability.

In particular, since the range of α in the general formula A _1- αBO _3- δ is 0.1 <α <0.15, the perovskite structure is stabilized and the A site is deficient. The introduction of oxygen vacancies, which plays an important role in the catalytic action, is promoted by controlling the valence due to, and the range of the oxygen vacancies δ that can be taken is 0 ≦ δ ≦ 1, so that Securing and improvement of durability are realized.

The A site deficient perovskite composite oxide according to claim 11 of the present invention is the A site deficient perovskite composite oxide represented by the general formula A _1- αBO ₃ δ A is La, Pr, Ce,
It is composed of at least one selected from the group consisting of Nd, Gd, Y, Ba, Sr, Ca, K and Pb, and B is T
i, Mn, Fe, Co, Ni, Cu and Al, which is composed of at least one kind of constituent element which is considered to have excellent heat resistance, and in which the range of α is 0. Since 1 <α <0.15 and the range of δ is 0 ≦ δ ≦ 1, stabilization of the perovskite is achieved, and valence control that makes an important contribution to the catalytic action is effective. The valence control of metal elements that are important for catalytic activity and facilitate the movement of oxygen vacancies introduced by valence control in the crystal lattice, and release and absorption characteristics of oxygen in the temperature range of 700 ° C or lower. It is possible to secure durability performance at the same time.

The A-site deficient perovskite composite oxide according to claim 12 of the present invention is the A-site deficient perovskite composite oxide represented by the general formula A _1- αBO ₃ -δ having the formula In the formula, A is A'and A ", and B is B'and B".
_1-x A ″ _x ) _1- α (B ′ _1-y B ″ _y ) O _{3 −} δ,
In the formula, A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is Pr, C
e, Ba, Sr, Ca, K and Pb, and at least one selected from the group consisting of B ′ and B ″, which are different elements, and are Mn, Co, Ti, Fe, Ni, Cu and Al. And at least one selected from the group consisting of α, δ, x, and y has a range of 0.1 <α <0.15, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, 0 ≦
When y ≦ 1, it is possible to control the electronic state of the B site by controlling the valence by changing x, and to form the A site deficient perovskite structure, and thus in the temperature range of 700 ° C. or lower. It is possible to improve the ability to release and absorb oxygen, and to improve heat resistance and durability. The reason that x ≦ 1 and 0 ≦ y ≦ 1 is set is that the perovskite structure is most stable in such a range.

The A site deficient perovskite composite oxide catalyst according to claim 13 of the present invention is the A according to claim 12.
_{In the} A-site deficient perovskite composite oxide represented by _1- δBO ₃ -α, in the formula, A is A ′ and A ″, and B is a general formula (A ′ ₁₎ composed of two constituent elements, B ′ and B ″. _-x A ″
_x ) _1- α (B ' _1-y B ″ _y ) O _3- δ (A ′ in the formula is L
It is composed of at least one selected from the group consisting of a, Nd, Gd and Y, and A ″ is Pr, Ce, Ba, Sr,
It is composed of at least one selected from the group consisting of Ca and K, B ′ and B ″ are different elements, and Mn and C
o, Ti, Fe, Ni, Cu and Al)), and the range of α, δ, x, y is 0.1 <α <
0.15, 0 ≤ δ ≤ 1, 0 ≤ x ≤ 1, 0 ≤ y ≤ 1 to change the combination of elements effective for catalytic activity by changing x and y, and By controlling the electronic state and forming the A-site deficient perovskite structure, it is possible to improve the catalytic activity and heat resistance and durability.

The A-site deficient perovskite complex oxide catalyst according to claim 14 of the present invention is the general formula (A ′ _1-x A ″ _x ) _1- α (B ′ _1-y B ″) according to claim 13. _y ) O _3- δ
Wherein A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is selected from the group consisting of Ce, Pr, Ba, Sr, Ca and K. B ′ is Co, B ″ is at least one selected from the group consisting of Mn, Fe, Ni and Al, and α, δ,
The possible ranges of x and y are 0.1 <α <0.1, respectively.
5, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y <1, so that the B site can be obtained by effectively utilizing the catalytic activity of Co and controlling the valence by changing x and y. It is possible to maintain the characteristics of the catalytic activity of Co and improve the heat resistance and durability by controlling the electronic state of (1) and forming an A-site deficient perovskite structure.

The A-site deficient perovskite composite oxide catalyst according to claim 15 of the present invention is the general formula (A ′ _1-x A ″ _x ) _1- α (B ′ _1-y B ″) according to claim 13. _y ) O _3- δ
Wherein A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is selected from the group consisting of Ce, Pr, Ba, Sr, Ca and K. B ′ is Mn, B ″ is at least one selected from the group consisting of Fe, Ti, and Cu, and α, δ, x, and y can be The ranges are 0.1 <α <0.15 and 0 ≦ δ, respectively.
By satisfying ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, Mn
To effectively control the electronic state of the B site by controlling the valence by changing x and y by effectively utilizing the catalytic activity of
By forming the A-site deficient perovskite structure, the catalytic activity of Mn can be maintained, and heat resistance and durability can be improved.

The A-site deficient perovskite composite oxide catalyst according to claim 16 of the present invention is the general formula (A ′ _1-x A ″ _x ) _1- α (B ′ _1-y B ″) according to claim 13. _y ) O _3- δ
And the possible ranges of α, δ, x, and y are 0.1 <α <0.15, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, 0, respectively.
At least Pd is supported as a noble metal on the A-site deficient perovskite composite oxide, which is characterized in that y <1, and stabilizes elements that are thought to adversely affect Pd and suppresses interaction with Pd. By doing so, the heat resistance and durability of the composite oxide catalyst containing at least Pd can be improved.

The A-site deficient perovskite complex oxide catalyst according to claim 17 of the present invention is the general formula (A ′ _1-x A ″ _x ) _1- α (Co _1-y B ″ _y ) according to claim 16. ) O _3- δ
Wherein A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is selected from the group consisting of Ce, Pr, Ba, Sr, Ca and K. B ″ is Mn, F
at least one selected from the group consisting of e, Ni and Al
The range of α, δ, x, and y is 0.1 <α <0.15, 0 ≦ δ ≦ 1, 0 ≦ x.
At least Pd is supported as a noble metal on the A-site deficient perovskite composite oxide, which is characterized in that ≦ 1, 0 <y ≦ 1, and stabilizes an element considered to adversely affect Pd. By suppressing the interaction, it is possible to improve the durability of the composite oxide catalyst containing at least Pd and provide the excellent exhaust gas-purifying three-way catalyst while utilizing the catalytic activity of Co.

The A-site deficient perovskite complex oxide catalyst according to claim 18 of the present invention is the general formula (A ′ _1-x A ″ _x ) _1- α (Mn _1-y B ″ _y ) according to claim 16. ) O _3- δ
Wherein A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is selected from the group consisting of Ce, Pr, Ba, Sr, Ca and K. B ″ is Fe and / or
Or Ti, and the ranges of α, δ, x, and y are 0.1 <α <0.15, 0 ≦ δ ≦ 1, and
At least Pd is supported as a noble metal on the A-site deficient perovskite composite oxide characterized by 0 ≦ x ≦ 1 and 0 ≦ y ≦ 1, and the elements considered to adversely affect Pd are stabilized, By suppressing the interaction with Pd, it is possible to improve the heat resistance and durability of the composite oxide catalyst containing at least Pd, and to provide a three-way catalyst for exhaust gas purification that utilizes the catalytic activity of Mn.

[0036]

EXAMPLES The present invention will be further described below with reference to Examples, Comparative Examples and Test Examples.

Example 1 A perovskite powder represented by La _0.9 Co _0.5 Fe _0.5 O ₃ -δ was produced by the following method (similar to the method described in JP-A-2-74505). Lanthanum, cobalt and iron carbonates or hydroxides (using powder having an average particle size of about 2 to 3 μm) were added as starting materials so that the respective molar ratios were La: Co: Fe = 9: 5: 5. , Crushed and mixed with a ball mill (after crushing,
Average particle size of mixed powder is about 1 μm). About 64 parts by weight of citric acid and 400 parts by weight of pure water were added to 100 parts by weight of the obtained mixture, and the mixture was reacted at 60 ± 5 ° C. After the reaction was completed, the obtained slurry was dehydrated at 120 ° C to obtain a complex citrate. The obtained complex citrate was calcined at 600 ° C. for 1 hour in the air, and then was calcined at 1100 ° C. for 5 hours to produce La _0.9 Co _0.5 Fe _0.5 O ₃ δ complex oxide powder. Also in the following Examples and Comparative Examples, unless otherwise specified, the perovskite powder was prepared in the same manner as in Example 1 except that the kinds and mixing ratios of the starting materials carbonate and hydroxide were changed. Manufactured.

Example 2 A perovskite powder represented by La _0.875 Co _0.5 Fe _0.5 O ₃ -δ was produced in exactly the same manner as in Example 1.

Example 3 A perovskite powder represented by La _0.85 Co _0.5 Fe _0.5 O ₃ -δ was produced in exactly the same manner as in Example 1.

Example 4 A perovskite powder represented by La _0.81 Ce _0.09 Co _0.5 Fe _0.5 O _3- δ was produced in exactly the same manner as in Example 1.

Example 5 A perovskite powder represented by La _0.72 Sr _0.18 Co _0.5 Fe _0.5 O _3- δ was produced in exactly the same manner as in Example 1.

Example 6 A perovskite powder represented by La _0.81 K _0.09 Co _0.5 Fe _0.5 O _3- δ was produced in exactly the same manner as in Example 1.

Example 7 A perovskite powder represented by La _0.72 Ba _0.18 Co _0.5 Fe _0.5 O _3- δ was produced in exactly the same manner as in Example 1.

Example 8 A perovskite powder represented by La _0.81 Pb _0.09 Co _0.5 Fe _0.5 O ₃ -δ was produced in exactly the same manner as in Example 1.

Example 9 A perovskite powder represented by La _0.81 Pr _0.09 Co _0.5 Fe _0.5 O _3- δ was produced in exactly the same manner as in Example 1.

Example 10 A perovskite powder represented by La _0.9 Co _0.8 Fe _0.2 O ₃ -δ was produced in exactly the same manner as in Example 1.

Example 11 A perovskite powder represented by La _0.9 Co _1.0 O _3- δ was produced in exactly the same manner as in Example 1.

Example 12 A perovskite powder represented by Nd _0.9 Mn _1.0 O ₃ -δ was produced in exactly the same manner as in Example 1.

Example 13 A perovskite powder represented by La _0.9 MnO ₃ δ was produced in exactly the same manner as in Example 1.

Example 14 A perovskite powder represented by La _0.9 Mn _0.5 Fe _0.5 O ₃ -δ was produced in exactly the same manner as in Example 1.

Example 15 A perovskite powder represented by La _0.81 K _0.09 Mn _0.8 Cu _0.2 O _3- δ was produced in exactly the same manner as in Example 1.

Example 16 A perovskite powder represented by Y _0.81 Ca _0.09 Mn _1.0 O _3- δ was produced in exactly the same manner as in Example 1.

Example 17 A perovskite powder represented by La _0.81 Sr _0.09 Mn _0.9 Ti _0.1 O ₃ -δ was produced in exactly the same manner as in Example 1 except that oxalate was used as a starting material for Ti.

Example 18 A perovskite powder represented by Gd _0.875 Mn _1.0 O _3- δ was produced in exactly the same manner as in Example 1.

Example 19 A perovskite powder represented by La _0.47 Sr _0.47 Co _0.98 Ni _0.02 O ₃ -δ was produced in exactly the same manner as in Example 1.

Example 20 A perovskite powder represented by La _0.7 Sr _0.175 Co _0.8 Fe _0.2 O ₃ -δ was produced in exactly the same manner as in Example 1.

Example 21 A perovskite powder represented by La _0.81 Sr _0.09 Co _0.95 Al _0.05 O _3- δ was produced in exactly the same manner as in Example 1.

Example 22 A perovskite powder represented by La _0.81 Ba _0.09 Co _0.5 Mn _0.5 O ₃ -δ was produced in exactly the same manner as in Example 1.

Example 23 Lanthanum and cobalt carbonate (using powder having an average particle size of about 2 to 3 μm) were used as starting materials, and the molar ratio of each was L.
a: Co = 8.75: 10 and crushed and mixed by a ball mill (after crushing, the average particle size of the mixed powder is about 1 μm).
m). Thereafter, in the same manner as in Example 1, La _0.875 CoO _3- δ
The perovskite powder represented by

Example 24 A perovskite powder represented by La _0.875 MnO _3- δ was produced in the same manner as in Example 23.

Example 25 A perovskite powder represented by La _0.78 Ce _0.1 Co _0.5 Fe _0.5 O _3- δ was produced in the same manner as in Example 23.

Example 26 A perovskite powder represented by La _0.78 Sr _0.1 Co _0.5 Fe _0.5 O _3- δ was produced in the same manner as in Example 23.

Example 27 A perovskite powder represented by La _0.78 K _0.1 Co _0.5 Fe _0.5 O _3- δ was produced in the same manner as in Example 23.

Example 28 A perovskite powder represented by La _0.78 Ba _0.1 Co _0.5 Fe _0.5 O ₃ -δ was produced in the same manner as in Example 23.

Example 29 A perovskite powder represented by La _0.78 Pb _0.1 Co _0.5 Fe _0.5 O _3- δ was produced in the same manner as in Example 23.

Example 30 A perovskite powder represented by Nd _0.875 MnO _3- δ was produced in the same manner as in Example 23.

Example 31 A perovskite powder represented by La _0.455 Ba _0.42 Mn _0.5 Fe _0.5 O _3- δ was produced in the same manner as in Example 23.

Example 32 A perovskite powder represented by La _0.78 K _0.1 Mn _0.8 Cu _0.2 O _3- δ was produced in the same manner as in Example 23.

Example 33 A perovskite powder represented by Y _0.78 Ca _0.1 MnO _3- δ was produced in the same manner as in Example 23.

Example 34 A perovskite powder represented by La _0.78 Sr _0.1 Mn _0.9 Ti _0.1 O ₃ -δ was produced in the same manner as in Example 23 except that oxalate was used as the Ti raw material.

Example 35 A perovskite powder represented by Gd _0.78 Pr _0.1 MnO _3- δ was produced in the same manner as in Example 23.

Example 36 A perovskite powder represented by La _0.44 Sr _0.44 Co _0.98 Ni _0.02 O ₃ -δ was produced in the same manner as in Example 23.

Example 37 A perovskite powder represented by La _0.78 Sr _0.1 Co _0.95 Al _0.05 O _3- δ was produced in the same manner as in Example 23 except that hydroxide was used as a starting material for Al.

Example 38 A perovskite powder represented by La _0.78 Ba _0.1 Co _0.5 Mn _0.5 O _3- δ was produced in the same manner as in Example 23.

Comparative Example 1 A perovskite powder represented by La _1.0 Co _0.5 Fe _0.5 O ₃ -δ was produced in exactly the same manner as in Example 1.

Comparative Example 2 A perovskite powder represented by La _0.9 Sr _0.1 Co _0.5 Fe _0.5 O ₃ -δ was produced in exactly the same manner as in Example 1.

Comparative Example 3 A perovskite powder represented by La _0.9 K _0.1 Co _0.5 Fe _0.5 O _3- δ was produced in exactly the same manner as in Example 1.

Comparative Example 4 A perovskite powder represented by La _0.8 Ba _0.2 Co _0.5 Fe _0.5 O ₃ -δ was produced in exactly the same manner as in Example 1.

Comparative Example 5 A perovskite powder represented by La _0.9 Pb _0.1 Co _0.5 Fe _0.5 O ₃ -δ was produced in exactly the same manner as in Example 1.

Comparative Example 6 A perovskite powder represented by La _1.0 Co _0.8 Fe _0.2 O _3- δ was manufactured in exactly the same manner as in Example 1.

Comparative Example 7 A perovskite powder represented by La _1.0 Co _1.0 O _3- δ was produced in exactly the same manner as in Example 1.

Comparative Example 8 A perovskite powder represented by Nd _1.0 Mn _1.0 O _3- δ was produced in exactly the same manner as in Example 1.

Comparative Example 9 A perovskite powder represented by La _1.0 Mn _0.5 Fe _0.5 O ₃ -δ was produced in exactly the same manner as in Example 1.

Comparative Example 10 A perovskite powder represented by La _0.9 K _0.1 Mn _0.8 Cu _0.2 O ₃ -δ was produced in exactly the same manner as in Example 1.

Comparative Example 11 A perovskite powder represented by Y _0.9 Ca _0.1 Mn _1.0 O ₃ -δ was produced in exactly the same manner as in Example 1.

Comparative Example 12 A perovskite powder represented by La _0.9 Sr _0.1 Mn _0.9 Ti _0.1 O ₃ δ was prepared in the same manner as in Example 1 except that oxalate was used as a starting material for Ti.

Comparative Example 13 A perovskite powder represented by GdMnO _3- δ was manufactured in exactly the same manner as in Example 1.

Comparative Example 14 A perovskite powder represented by La _0.5 Sr _0.5 Co _0.98 Ni _0.02 O ₃ -δ was produced in exactly the same manner as in Example 1.

Comparative Example 15 A perovskite powder represented by La _0.8 Sr _0.2 Co _0.8 Fe _0.2 O ₃ -δ was produced in exactly the same manner as in Example 1.

Comparative Example 16 A perovskite powder represented by La _0.9 Sr _0.1 Co _0.95 Al _0.05 O _3- δ was produced in exactly the same manner as in Example 1.

Comparative Example 17 A perovskite powder represented by La _0.9 Ba _0.1 Co _0.5 Mn _0.5 O ₃ -δ was produced in exactly the same manner as in Example 1.

Comparative Example 18 A perovskite powder represented by La _1.0 Mn _1.0 O _3- δ was produced in the same manner as in Example 23.

Comparative Example 19 A perovskite powder represented by La _1.0 Co _0.5 Fe _0.5 O _3- δ was produced in the same manner as in Example 23.

Comparative Example 20 A perovskite powder represented by La _0.9 Ce _0.1 Co _0.5 Fe _0.5 O ₃ -δ was produced in exactly the same manner as in Example 23.

Comparative Example 21 A perovskite powder represented by La _0.9 Ba _0.1 Co _0.5 Fe _0.5 O _3- δ was produced in the same manner as in Example 23.

Comparative Example 22 A perovskite powder represented by La _0.5 Ba _0.5 Mn _0.5 Fe _0.5 O _3- δ was produced in the same manner as in Example 23.

Test Example 1 With respect to the perovskites obtained in Examples 1 to 11 and Comparative Examples 1 to 7, the effect of suppressing the solid phase reaction between the perovskite and the oxide in contact with it was examined. The solid-phase reactivity of the base material in the A-site deficient type according to the present invention and the conventional perovskite with respect to γ-alumina was judged by performing durability and evaluation under the following conditions.

(Solid phase reaction evaluation method) 1) Preparation of evaluation sample (1) Perovskite powder of each specification: γ-alumina =
Weighed so as to be 1: 2 (weight ratio) (2) Weighed powder is dry mixed in an agate mortar for 1 hour (3) Mixed powder at 1 ton / cm ² about 3 × 5 × 20 mm ³
(4) Durability by heat treatment of the molded body at 900 ° C. or 1100 ° C. for 5 hours in air 2) Evaluation of solid-phase reaction by X-ray diffraction (1) Measurement of intensity of X-ray diffraction peak of generated phase ( 2) Measurement of intensity ratio of X-ray diffraction peak between perovskite and generated phase

FIG. 1 shows an example of an X-ray diffraction pattern after the solid phase reaction in Example 1 and Comparative Example 1 which were durable at 900 ° C. and 1100 ° C. As shown in FIGS. 1 (a) and 1 (b), in durability at 900 ° C., a normal perovskite La _1.0 Co _0.5 Fe _0.5 O _{3 −} δ (Comparative Example 1) was reacted with alumina to produce LaAlO ₃ and spinel. The formation of a phase was confirmed.

It is considered that by advancing the solid-phase reaction that produces these reaction products, the perovskite is decomposed and the specific surface area is reduced accordingly, and as a result, the catalytic activity of the perovskite is lowered. This result means that, in addition to the result that the generation mechanism of the spinel phase is the trigger of the reaction, the deterioration mechanism by the reaction of the perovskite with the base material is related to the generation of LaAlO ₃ .

Furthermore, in durability at 1100 ° C.
However, according to Example 1, although the production phase by the solid phase reaction is seen.
That the A-site deficient type suppresses the solid-phase reaction
I understand. This means that the A-site-defective perov of the present invention is
SKYTE La_0.9Co_0.5Fe _0.5O_3-δ (Example 1)
In the case of LaAlO_ThreeSuppresses the generation of
Degradation of perovskite and its
Meaning that it is possible to suppress the decrease in specific surface area that accompanies
doing.

Also, when the perovskite is highly dispersed and carried on the surface of a zirconia-based substrate, a solid phase reaction occurs between the perovskite component and zirconia in a high temperature region, and a sufficient dispersion effect is obtained. Not available (N. Mi
zuno et al. : J. Am. Chem. So
c. Vol. 114, 7151 (1992)), and based on these results, using LaCoO _{3 −} δ as an example to simplify the system, the solid-state reaction formula with the substrate is schematically shown. It is shown in FIG.

Based on the results of such analysis, a sample for evaluation was prepared according to the procedure described in the above (solid phase reaction evaluation method),
Durability was performed at 1100 ° C. At this time, the X-ray diffraction peak intensity ratio of the production phase LaAlO ₃ for the resulting perovskite the (I [LaAlO _3] / I [perovskite]) as an index to evaluate the degree of perovskite degradation by solid phase reaction. The obtained results are shown by the production ratio I [LaAlO ₃ ] / I of LaAlO ₃ in each perovskite composition.
It shows in Table 1 as [perovskite].

[0104]

[Table 1]

At this time, precipitation of the second phase was observed in the composition region where α was 0.2 or more, and the A-site perovskite single phase could not be obtained. In addition, as is clear from Table 1, the compositions shown in Examples 1 to 11 with respect to the compositions shown in Comparative Examples 1 to 7 and the general formula (A ′ _1-x A ″ _x )
_1- α (B ' _1-y B ″ _y ) O _3- δ, and α, δ,
The possible ranges of x and y are 0 <α <0.2 and 0 ≦, respectively.
By forming an A-site deficient perovskite composite oxide characterized by δ ≦ 1, 0 ≦ x ≦ 1, and 0 ≦ y ≦ 1, it is possible to suppress the generation of LaAlO ₃ and improve the durability of the perovskite. It becomes possible.

Further, by making it the A site deficient type,
Effective control of valence, which makes an important contribution to catalysis.
The theoretical consideration using the lattice defect theory is that
It is possible to make an argument from the guess. LaCoO_3-δ is an example
Valency that improves the catalytic activity of perovskites
Explaining the control, one of the +3 valent La that occupies the A site
By substituting parts with +2 valent Sr having different charges
The chemical activation can be greatly improved, but this is
Depending on the concentration of oxygen in the air,
It is thought that this is due to reversible entry and exit (Tanaka, Taka
Hashi: Automotive Technology, Vol. 47p51 (1993)). La³⁺ _1-XSr²⁺ _xCo³⁺ _1-xCo⁴⁺ _xO_Three <===
=> La³⁺ _1-XSr²⁺ _xCo³⁺ _{1-x + 2}δCo⁴⁺ _x-2δO_3-
δ + (1 / 2δ) O ₂

The same argument can be applied to the Mn-based perovskite, in which the A site has a different valence, that is, +2.
FIG. 3 shows the relationship between the valence Sr, the +1 valence K, and the oxygen deficiency amount δ when it is replaced with the A site deficiency (+3 valence La vacancies) invented this time. As is apparent from FIG. 3, the inflow and outflow of oxygen involved in the reaction is controlled by substituting different valences for the A site.

As shown here, the A-site deletion is S
It is shown that more oxygen vacancies are introduced than is normally introduced by valence control by the substitution of r or K. This means that the valence can be effectively controlled even if the amount of the substituting element that tends to adversely affect the performance of the supported noble metal catalyst is reduced. In addition, as described above, it is possible to realize a perovskite composite oxide which suppresses the solid-phase reaction with the base material and has durability and excellent catalytic activity. Next, the effectiveness of the present invention for improving the durability and catalytic activity of perovskites was examined by the evaluation method according to Test Example 2.

Test Example 2 With respect to the perovskites of Examples 12 to 15 and Comparative Examples 8, 18, and 9 to 10, the deterioration of the catalytic properties due to the solid phase reaction between the perovskites and the alumina in contact with them was examined. The effect of suppressing deterioration of the catalytic activity due to the solid-phase reaction occurring in the base material γ-alumina of the A-site deficient type according to the present invention and the conventional perovskite was judged by performing durability and evaluation under the following conditions.

(Catalyst activity evaluation method I) 1) Preparation of evaluation sample (1) Perovskite powder of each specification: γ-alumina =
Weighed so as to be 1: 2 (weight ratio) (2) Weighed powder is dry-mixed in an agate mortar for 1 hour (3) Mixed powder is heated and heated at 900 ° C. for 10 hours in the air to endure 2) Reaction evaluation (1) Reaction evaluation gas C ₃ H ₆ : 2200 ppm O ₂ : 4.5% He: Residual (2) Evaluation of reaction characteristics The temperature (T ₅₀ ) at which the conversion rate becomes 50% while heating is measured.

Examples 12 to 15 and Comparative Examples 8, 18, 9
Table 2 shows the catalytic activity evaluation results for Nos. 10 to 10.

[0112]

[Table 2]

As shown in Table 2, the evaluation results after durability are
In each of the examples, T ₅₀ is lower than that of the corresponding comparative example, the catalytic activity is higher, and it is understood that the A-site deficient type is effective in improving the catalytic activity after endurance. Also, P
The evaluation method according to Test Example 3 examined that the present invention is effective for improving the durability performance of the perovskite after supporting d.

Test Example 3 With respect to the perovskites of Examples 16 to 22 and Comparative Examples 11 to 17, the deterioration of the catalytic properties due to the solid phase reaction between the perovskite supporting Pd and the alumina in contact was examined. The effect of suppressing deterioration of the catalytic activity due to the solid-phase reaction occurring in the base material γ-alumina of the A-site deficient type according to the present invention and the conventional perovskite was judged by performing durability and evaluation under the following conditions.

(Catalytic activity evaluation method II) 1) Preparation of evaluation sample (1) Palladium chloride solution was used for perovskite powder of each specification, and 2% by weight of Pd was carried. (2) Perovskite powder of each specification carrying Pd. : Γ-alumina = 1: 2 (weight ratio) (3) Weighing powder is dry-mixed in an agate mortar for 1 hour (4) Mixture powder is heat-treated at 900 ° C for 10 hours in air to endure 2) reaction evaluation (1) evaluation of reaction gas _{C 3 H 6: 2200ppm O 2} : 4.5% He: measuring the remaining (2) reaction characterization temperature raised while conversion is 50% (T ₅₀₎

Table 3 shows the evaluation results of the catalytic activity in Examples 16 to 22 and Comparative Examples 11 to 17.

[0117]

[Table 3]

In the evaluation results after the endurance, each Example had a lower T ₅₀ and a higher catalytic activity than the corresponding Comparative Examples.
It is shown that the A-site deficient type is effective in improving the catalytic activity after endurance. This means that it is also effective for improving the durability performance of the perovskite catalyst after supporting Pd.

Test Example 4 Examples 1, 11, 13, 23 and 24, Comparative Examples 7 and 18,
The 19 perovskites were subjected to thermogravimetric analysis in order to evaluate the oxygen release behavior, which is one of the indicators of the catalytic activity of the perovskites. The comparative study of oxygen release performance between the A-site deficient perovskite and the conventional perovskite having excellent durability performance and improved oxygen release performance according to the present invention was judged by performing thermogravimetric analysis under the following conditions.

(Evaluation method) 1) Evaluation apparatus (1) Perkin Elmer TGA72 2) Measurement conditions (1) Measurement temperature range: room temperature to 1200 ° C. (2) Measurement atmosphere: dry air (3) Temperature rising rate: 10 ° C / min

The results of thermogravimetric analysis in Examples 11 and 23 and Comparative Example 7 are shown in FIG. La _0.9 Co _0.5 O ₃ −δ (Example 11) in the temperature range of 200 ° C. to 400 ° C.
Has a lower oxygen releasing ability than the ordinary perovskite La _1.0 CoO ₃ −δ (Comparative Example 7). When actually used as a purification catalyst, in addition to durability and heat resistance,
Further improvement in catalytic activity is desired. La _0.875 CoO ₃
It can be seen that by using the A-site deficient perovskite in −δ (Example 23), the oxygen-releasing ability is improved in the temperature range of 700 ° C. or lower compared to the conventional A-site deficient perovskite composition. Similarly, Example 1
The comparison result of 3 and 24 and the comparative example 18 is shown in FIG. Furthermore, the comparison result of Examples 1 and 2 and Comparative Example 19 is shown in FIG. As is clear from these results, the amount of A site deficiency α
It can be seen that the A-site deficient perovskite excellent in oxygen release performance can be obtained by setting 0.1 to α <0.15. Next, the effectiveness of the present invention for improving the durability and catalytic activity of perovskites was examined by the evaluation method according to Test Example 5.

Test Example 5 Examples 23 to 24, 2, 25 to 32 and corresponding Comparative Examples 7, 18 to 20, 2 to 3, 21, 5, 8, 22, and
With respect to the 10 perovskites, the catalyst activity deterioration and the catalyst activity improving effects due to the solid-state reaction between the perovskites and the alumina in contact with the perovskites were examined. According to the present invention, the catalyst performance of the A-site deficient perovskite and the conventional A-site deficient perovskite whose durability, heat resistance and oxygen-releasing performance are voluntary is examined under the same conditions as the catalyst activity evaluation method I of Test 2. It was judged by carrying out the evaluation.

Examples 23 to 24, 2, 25 to 32 and corresponding Comparative Examples 7, 18 to 20, 2-3 and 21,
Table 4 shows the catalytic activity evaluation results for 5, 8, 22, and 10. The evaluation results after endurance were as follows. In each of the examples, T ₅₀ was lower than that of the corresponding comparative example, the catalytic activity was higher, and the A-site deficiency amount α was set to 0.1 <α <0.15. It can be seen that it is effective for improving the catalytic activity of.

[0124]

[Table 4]

Furthermore, it was examined by the evaluation method according to Test Example 6 that the present invention is effective for improving the durability performance of the perovskite after supporting Pd.

Test Example 6 With respect to the perovskites of Examples 33 to 38 and Comparative Examples 11 to 14 and 16 to 17, deterioration of catalytic activity due to solid phase reaction between the perovskite supporting Pd and alumina in contact with the perovskite was examined. The effect of suppressing the catalytic activity deterioration due to the solid-phase reaction that occurs in the base material γ-alumina in the A-site deficient type according to the present invention and the conventional perovskite is evaluated as durability under the same conditions as in the catalytic activity evaluation method II of Test Example 3. It was judged by performing.

Examples 33 to 38 and Comparative Examples 11 to 14,
Table 5 shows the catalytic activity evaluation results for 16 to 17. The evaluation results after endurance show that in each Example, T ₅₀ is lower than that of the corresponding comparative example, the catalytic activity is higher, and the amount of A site deficiency is effective in improving the catalytic activity after endurance. ing. That is, it is understood that the present invention is effective for improving the durability performance of the perovskite catalyst after supporting Pd.

[0128]

[Table 5]

[0129]

As described above, the defective type of the present invention is used.
The composition of the rovskite composite oxide is reduced.
Also the general formula A_1-αBO_3-Smell of complex oxide represented by δ
Therefore, the range of α is 0 <α <0.2, preferably
0.1 <α <0.15 and the range of δ
Where A is 0 ≦ δ ≦ 1
The compound of general formula (A '_1-x
A ″_x)_1-δ (B '_1-yB " _y) O_3-represented by α, and
The possible ranges of α, δ, x, and y are 0 <α <0.
2, preferably 0.1 <α <0.15, 0 ≦ δ ≦ 1,
A size characterized by 0 ≦ x ≦ 1 and 0 ≦ y ≦ 1
By using a deficient perovskite composite oxide,
LaAlO_ThreeSuppresses the generation of, has durability, catalytic activity
Excellent perovskite complex oxide and its touch
A medium can be supplied.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction pattern of a perovskite / alumina mixed powder sintered body. This X-ray diffraction pattern shows the conventional perovskite La _1.0 Co _0.5 Fe _0.5 O _3- δ (Comparative Example 1) and the La _0.9 Co _0.5 Fe _0.5 O _3- δ according to the present invention.
This is a comparison with (Example 1).

FIG. 2 is a solid-phase reaction formula in a LaCoO _3- δ / base material (alumina, zirconia) system.

FIG. 3 is a diagram comparing the effects of valence control in Mn-based perovskites.

FIG. 4 La₁-ΑCoO_3-α in δ is 0.0
Conventional perovskite (Comparative Example 7) and L according to the present invention
a_0.9CoO_3-δ (Example 11) and La_0.875CoO
_3-The results of thermogravimetric analysis with δ (Example 23) are shown in comparison.
FIG.

FIG. 5 shows a conventional perovskite in which α in La ₁ -αMnO _3- δ is 0.0 (Comparative Example 18) and La _0.9 MnO ₃ -δ (Example 13) and La _0.875 Mn according to the present invention.
FIG. 9 is a diagram showing the results of thermogravimetric analysis in comparison with O _{3 −} δ (Example 24).

FIG. 6 α in La ₁ −αCo _0.5 Fe _0.5 O ₃ −δ
A conventional perovskite having a value of 0.0 (Comparative Example 19) and La _0.9 Co _0.5 Fe _0.5 O _3- δ (Example 1) and La _0.875 Co _0.5 Fe _0.5 O _3- δ (Example 2) according to the present invention. It is a diagram which compares and shows the thermogravimetric analysis result of.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01D 53/94 B01J 23/18 ZABA B01J 23/02 ZAB 23/34 ZABA 23/04 ZAB 23/76 ZABA 23/10 ZAB 23/78 ZABA 23/14 ZAB 23/84 ZAB 23/18 ZAB ZABA 23/34 ZAB 23/89 ZABA 23/76 ZAB C01F 7/04 Z 23/78 ZAB 7/16 23/835 ZAB 17/00 ZABB 23/84 ZAB C01G 3/00 ZAB 23/00 ZABB 23/889 29/00 ZAB 23/89 ZAB 45/00 ZAB C01F 7/04 49/00 ZAB 7/16 51/00 ZABA 17/00 ZAB 53/00 ZABA C01G 3/00 ZAB B01D 53/34 ZAB 23/00 ZAB 129A 29/00 ZAB 53/36 ZAB 45/00 ZAB 102B 49/00 ZAB B 1J 23/82 ZABA 51/00 ZAB 23/84 311A 53/00 ZAB (72) inventor Miyamoto Takeshi Kanagawa Prefecture, Kanagawa-ku, Yokohama-shi Takaracho Address 2 Nissan-car Co., Ltd.

Claims (18)

[Claims] 1. A site in a perovskite structure
Composition ratio of B-site element to element {(BA) /
B} ratio = α is greater than 0, the general formula A_1-αBO _3-δ (expression
A is an alkali metal element, alkaline earth element, rare earth
A small number of elements selected from the group consisting of group elements, Y, Bi and Pb
It is composed of at least one kind, and B is a 3d transition metal element and
A / site-deficient type represented by
Range of α in perovskite complex oxide
Is 0 <α <0.2, and the range of δ is 0
A-site deficient perov characterized by ≦ δ ≦ 1
Skytite complex oxide. 2. In the A-site deficient perovskite composite oxide represented by the general formula A _1- αBO _3- δ according to claim 1, A in the formula is La, Pr, Ce, Nd, Gd, E.
r, Y, Bi, Ba, Sr, Ca, K and Pb, and at least one selected from the group consisting of
It is composed of at least one selected from the group consisting of i, Mn, Fe, Co, Ni, Cu and Al, and the range of α can be 0 <α <0.2 and δ can be. A site deficient perovskite composite oxide characterized in that the range is 0 ≦ δ ≦ 1. 3. The A-site deficient perovskite composite oxide represented by the general formula A _1- αBO ₃ -δ according to claim 1, wherein A is A ′ and A ″ and B is B ′ and B. A general formula (A ′ _1-x A ″ _x ) _1- α consisting of two types of constituent elements
(B ′ _1-y B ″ _y ) O _3- δ (A ′ in the formula is La, Nd,
At least one selected from the group consisting of Gd, Y and Bi
A "is Pr, Ce, Ba, Sr, C
It is composed of at least one selected from the group consisting of a, K and Pb, and B ′ and B ″ are Mn, Co, Ti and F.
e, Ni, Cu and at least one selected from the group consisting of Al), and α,
The possible ranges of δ, x, and y are 0 <α <0.2,
An A-site deficient perovskite complex oxide, wherein 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, and 0 ≦ y ≦ 1. 4. The A-site deficient perovskite composite oxide represented by the general formula A _1- αBO ₃ -δ according to claim ₃ , wherein A is A ′ and A ″ and B is B ′ and B. A general formula (A ′ _1-x A ″ _x ) _1- α consisting of two types of constituent elements
(B ′ _1-y B ″ _y ) O _3- δ (A ′ in the formula is La, Nd,
It is composed of at least one selected from the group consisting of Gd and Y, and A ″ is Pr, Ce, Ba, Sr, Ca and K.
Consisting of at least one selected from the group consisting of
B ′ and B ″ are composed of at least one selected from the group consisting of Mn, Co, Ti, Fe, Ni, Cu and Al), and α, δ, x, y The obtained ranges are 0 <α <0.2, 0 ≦ δ ≦ 1, and 0 ≦ x ≦, respectively.
1. A site deficient perovskite composite oxide catalyst, characterized in that 1, 0 ≦ y ≦ 1. 5. The general formula (A ′) according to claim 4.
_1-x A ″ _x ) _1- α (B ′ _1-y B ″ _y ) O _{3 −} δ,
In the formula, A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is Ce, P
It is composed of at least one selected from the group consisting of r, Ba, Sr, Ca and K, B ′ is Co and B ″ is at least one selected from the group consisting of Mn, Fe, Ni and Al. And the possible ranges of α, δ, x, and y are 0 <α <0.2, 0 ≦ δ ≦ 1, and 0 ≦ x, respectively.
A site deficient perovskite composite oxide catalyst, wherein ≦ 1, 0 ≦ y <1. 6. The general formula (A ′) according to claim 4.
_1-x A ″ _x ) _1- α (B ′ _1-y B ″ _y ) O _{3 −} δ,
In the formula, A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is Ce, P
It is composed of at least one selected from the group consisting of r, Ba, Sr, Ca and K, B ′ is Mn and B ″ is composed of at least one selected from the group consisting of Fe, Ti and Cu. And the possible ranges of α, δ, x, y are 0 <α <0.2, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1,
A site deficient perovskite composite oxide catalyst, characterized in that 0 ≦ y ≦ 1. 7. The general formula (A ′) according to claim 4.
_1-x A ″ _x ) _1- α (B ′ _1-y B ″ _y ) O _{3 −} δ,
In addition, the possible range of α, δ, x, and y is 0 <α <
0.2, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1 At least Pd is supported as a noble metal on the A-site deficient perovskite composite oxide. Complex oxide catalyst. 8. The general formula (A ′) according to claim 7.
_1-x A ″ _x ) _1- α (Co _1-y B ″ _y ) O _{3 −} δ,
In the formula, A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is Ce, P
r, Ba, Sr, Ca and K, and at least one selected from the group consisting of Mn, Fe, Ni and Al, and B ″. The possible range of δ, x, y is 0.
<Α <0.2, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, 0 <y ≦ 1, at least Pd as a noble metal is supported on the A-site deficient perovskite composite oxide. A characteristic composite oxide catalyst. 9. The general formula (A ′) according to claim 7.
_1-x A ″ _x ) _1- α (Mn _1-y B ″ _y ) O _{3 −} δ,
In the formula, A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is Ce, P
It is composed of at least one selected from the group consisting of r, Ba, Sr, Ca and K, and B ″ is Fe and / or Ti.
And the range of possible values of α, δ, x, and y is 0 <α <0.2, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, 0 ≦, respectively.
A composite oxide catalyst in which at least Pd is supported as a noble metal on an A-site deficient perovskite composite oxide characterized in that y ≦ 1. 10. In the perovskite structure, the composition ratio of B site element to A site element {(BA) /
B} ratio = α is greater than 0 and has the general formula A _1- αBO _3- δ (A in the formula is at least 1 selected from the group consisting of alkali metal elements, alkaline earth elements, rare earth elements, Y and Pb). B is Ti, Mn, Fe, Co, N
In the A-site deficient composite oxide represented by (composed of at least one selected from the group consisting of i, Cu and Al), the range of α is 0.1 <α <0.1.
5. An A-site deficient perovskite complex oxide, which is 5 and the range of δ is 0 ≦ δ ≦ 1. 11. The general formula A _1- αBO ₃ -of claim 10.
In the A-site deficient perovskite composite oxide represented by δ, A in the formula is La, Pr, Ce, Nd, or G.
It is composed of at least one selected from the group consisting of d, Y, Ba, Sr, Ca, K and Pb, and B is Ti, M
It is composed of at least one selected from the group consisting of n, Fe, Co, Ni, Cu and Al, and the range of α is 0.1 <α <0.15 and the range of δ is possible. Is 0 ≦ δ ≦ 1. A site deficient perovskite composite oxide. 12. The general formula A _1- αBO ₃ -of claim 11.
In the A-site deficient perovskite composite oxide represented by δ, in the formula, A is A ′ and A ″, and B is B ′ and B ″.
General formula (A ′ _1-x A ″ _x ) _1- α consisting of various constituent elements
(B ′ _1-y B ″ _y ) O _3- δ (A ′ in the formula is La, Nd,
It is composed of at least one member selected from the group consisting of Gd and Y, A ″ is composed of at least one member selected from the group consisting of Pr, Ce, Ba, Sr, Ca, K and Pb, and B ′ is B ″ is a different element, and Mn, Co,
And at least one selected from the group consisting of Ti, Fe, Ni, Cu, and Al), and the range of α, δ, x, and y is 0.1 <α.
<0.15, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, A site deficient perovskite complex oxide. 13. The general formula A _1- αBO ₃ -of claim 12.
In the A-site deficient perovskite composite oxide represented by δ, in the formula, A is A ′ and A ″, and B is B ′ and B ″.
General formula (A ′ _1-x A ″ _x ) _1- α consisting of various constituent elements
(B ′ _1-y B ″ _y ) O _3- δ (A ′ in the formula is La, Nd,
It is composed of at least one selected from the group consisting of Gd and Y, and A ″ is Pr, Ce, Ba, Sr, Ca and K.
Consisting of at least one selected from the group consisting of
B ′ and B ″ are different elements and include Mn, Co, Ti,
And at least one selected from the group consisting of Fe, Ni, Cu and Al), and α,
The possible ranges of δ, x, and y are 0.1 <α <0.
15. A-site deficient perovskite complex oxide catalyst, characterized in that: 15, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1. 14. The general formula (A ′) according to claim 13.
_1-x A ″ _x ) _1- α (B ′ _{1- y} B ″ _y ) O _3- δ,
In the formula, A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is Ce, P
It is composed of at least one selected from the group consisting of r, Ba, Sr, Ca and K, B ′ is Co and B ″ is at least one selected from the group consisting of Mn, Fe, Ni and Al. And the range of possible values of α, δ, x, y is 0.1 <α <0.15, 0 ≦ δ ≦ 1,
An A-site deficient perovskite complex oxide catalyst, characterized in that 0 ≦ x ≦ 1 and 0 ≦ y <1. 15. The general formula (A ′) according to claim 13.
_1-x A ″ _x ) _1- α (B ′ _{1- y} B ″ _y ) O _3- δ,
In the formula, A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is Ce, P
It is composed of at least one selected from the group consisting of r, Ba, Sr, Ca and K, B ′ is Mn and B ″ is composed of at least one selected from the group consisting of Fe, Ti and Cu. And the possible ranges of α, δ, x, y are 0.1 <α <0.15, 0 ≦ δ ≦ 1, 0 ≦ x, respectively.
A site deficient perovskite composite oxide catalyst, wherein ≦ 1, 0 ≦ y ≦ 1. 16. The general formula (A ′) according to claim 13.
_1-x A ″ _x ) _1- α (B ′ _{1- y} B ″ _y ) O _3- δ,
And the range of possible values of α, δ, x, y is 0.1 <
At least Pd is supported as a noble metal on an A-site deficient perovskite complex oxide having α <0.15, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, and 0 ≦ y ≦ 1. catalyst. 17. The general formula (A ′) according to claim 16.
_1-x A ″ _x ) _1- α (Co _{1- y} B ″ _y ) O _{3 −} δ,
In the formula, A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is Ce, P
r, Ba, Sr, Ca and K, and at least one selected from the group consisting of Mn, Fe, Ni and Al, and B ″. The possible ranges of δ, x, and y are 0.1 <α <0.15, 0 ≦ δ ≦ 1, 0 ≦ x ≦ 1, 0 <, respectively.
A composite oxide catalyst in which at least Pd is supported as a noble metal on an A-site deficient perovskite composite oxide with y ≦ 1. 18. The general formula (A ′) according to claim 16.
_1-x A ″ _x ) _1- α (Mn _{1- y} B ″ _y ) O _3- δ,
In the formula, A ′ is composed of at least one selected from the group consisting of La, Nd, Gd and Y, and A ″ is Ce, P
It is composed of at least one selected from the group consisting of r, Ba, Sr, Ca and K, and B ″ is Fe and / or Ti.
And the range in which α, δ, x, y can be 0.1 <α <0.15, 0 ≦ δ ≦ 1, 0 ≦ x ≦
In the A-site deficient perovskite complex oxide, which is characterized in that 1, 0 ≦ y ≦ 1, at least P as a noble metal.
A composite oxide catalyst in which d is supported.