JP5182850B2 - Perovskite complex oxide - Google Patents

Description

  The present invention relates to a perovskite complex oxide and a method for producing the same.

The polymer electrolyte fuel cell uses an ion exchange membrane as an electrolyte, operates at a relatively low temperature from room temperature to about 100 ° C., has a high output density, and can be reduced in size and weight. It has attracted widespread attention because of its features.

  At present, as the fuel supplied to the polymer electrolyte fuel cell, hydrogen gas, reformed gas obtained by reforming natural gas, methanol, or the like is used. However, the reformed gas contains catalyst poisons such as carbon monoxide, and platinum, which has been widely used as an electrode material for polymer electrolyte fuel cells, has a trace amount of carbon monoxide. Due to the presence, there is a problem that the catalytic performance of the electrode is impaired and the battery performance is greatly reduced.

  Platinum-ruthenium is known as a catalyst having excellent oxidation characteristics with respect to carbon monoxide, but it cannot be said that it has sufficient performance for practical use as a fuel cell, and it can further improve the catalyst performance. It is desired (see Non-Patent Document 1 below).

For this reason, development of a catalyst that is resistant to carbon monoxide poisoning and that can exhibit excellent performance even in the presence of carbon monoxide has become an important issue.
M. Watanabe, “Handbook of Fuel Cells -Fundamentals Technology and Applications”, Vol.2, Wiley, Chichester, 2003, p.408-415.

  The present invention has been made in view of the current state of the prior art described above, and its main purpose is to have excellent catalytic performance as a catalyst for a polymer electrolyte fuel cell, and in particular, selective to carbon monoxide. It is to provide a novel material that has excellent oxidation characteristics and can exhibit excellent performance as an electrode catalyst for a fuel cell even in the presence of carbon monoxide.

  The present inventor has intensively studied to achieve the above-described object. As a result, a specific perovskite type complex oxide having a perovskite type crystal structure having a specific composition and having a tolerance factor representing the degree of distortion of the crystal structure within a range of 0.9 to By contacting with the noble metal vapor or the noble metal oxide vapor, a part of the constituent elements of the composite oxide was replaced by the noble metal element, and the noble metal element was included in the crystal structure of the perovskite complex oxide It has been found that a novel composite oxide can be obtained. Further, by reducing the noble metal-containing perovskite complex oxide, a part of the noble metal element contained in the perovskite complex oxide is precipitated as noble metal fine particles, and the particulate noble metal is formed on the perovskite complex oxide. It has been found that a supported carrier is formed. The carrier is found to be a material having good selective oxidizability for carbon monoxide and having excellent catalytic activity as a fuel electrode catalyst for a fuel cell, and the present invention is completed here. It came to.

That is, the present invention provides the following perovskite complex oxide and a method for producing the same.
1. The following composition formula (1):
_{(Ba 1-x A x)} BH a O 3-b (1)
(In the formula, A is at least one element selected from the group consisting of a lanthanoid element and an element of Group 2 of the periodic table, and B is an element of Group 3 of the periodic table, an element of Group 4 of the periodic table, and periodic table 13) And at least one element selected from the group consisting of transition metal elements in the fourth period of the periodic table, wherein each symbol of x, a and b represents a numerical value in the following range: 0 ≦ x ≦ 1, 0 <a ≦ 0.5, 0 <b ≦ 0.25),
Following formula:
t = (r _A + r _O ) / (2 ^1/2 · (r _B + r _O ))
(Wherein r _A is the arithmetic mean of the ionic radii of Ba and A, r _B is the arithmetic mean of the ionic radii of B, and r _O is the ionic radius of the oxide ion (O ²⁻ ) (1.40Å). The perovskite type complex oxide having a tolerance factor (t) defined in (1) in the range of 0.9 to 1.

2. The following composition formula (2):
(Ba _1-xy A _x M ¹ _y ) (B _1-z M ² _z ) H _a O _3-b (2) (wherein A is a group consisting of a lanthanoid element and a Group 2 element of the periodic table) And B is a group consisting of an element of Group 3 of the periodic table, an element of Group 4 of the periodic table, an element of Group 13 of the periodic table, and a transition metal element of the fourth period of the periodic table M ¹ and M ² are the same or different and are each at least one noble metal element selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Au, and Ag. Each symbol of x, y, z, a and b represents a numerical value in the following range: 0 ≦ x ≦ 1, 0 ≦ y <0.3, 0 ≦ z <0.3, 0 <a ≦ 0 .5, 0 <b ≦ 0.25: where the total value of y and z is 0 <y + z <0.6)
Following formula:
t = (r _A + r _O ) / (2 ^1/2 · (r _B + r _O ))
(Wherein r _A is the arithmetic mean of the ionic radii of Ba, A and M ¹ , r _B is the arithmetic mean of the ionic radii of B and M ² , and r _O is the oxide ion (O ²⁻ )). A noble metal-containing perovskite complex oxide having a tolerance factor (t) defined by an ionic radius (1.40 Å) in a range of 0.9 to 1.

3. The following composition formula (3):
(Ba _1-xy A _x M ¹ _yc ) (B _1-z M ² _zd ) H _a O _3-b (3) (wherein A is a lanthanoid element and periodic group 2 of the periodic table) At least one element selected from the group consisting of elements, wherein B is an element of Group 3 of the periodic table, an element of Group 4 of the periodic table, an element of Group 13 of the periodic table, and a transition metal of the fourth period of the periodic table And at least one element selected from the group consisting of elements, wherein M ¹ and M ² are the same or different and are at least selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Au, and Ag, respectively. Each of the symbols x, y, z, a, b, c, and d represents a numerical value in the following range: 0 ≦ x ≦ 1, 0 ≦ y <0.3, 0 ≦ z <0. .3, 0 <a ≦ 0.5, 0 <b ≦ 0.25, 0 ≦ c <0.1, 0 ≦ d <0.1; however, the total value of y and z is 0 <y + z <0. In it, c is following numbers y, d is a following values z, the sum of c and d is represented by a 0 <c + d <0.2.),
Following formula:
t = (r _A + r _O ) / (2 ^1/2 · (r _B + r _O ))
(Wherein r _A is the arithmetic mean of the ionic radii of Ba, A and M ¹ , r _B is the arithmetic mean of the ionic radii of B and M ² , and r _O is the oxide ion (O ²⁻ )). On the surface of the perovskite complex oxide having a tolerance factor (t) defined by an ionic radius (1.40 Å) in the range of 0.9 to 1,
A noble metal-supported perovskite-type composite oxide in which a noble metal consisting of M ^{1 in} an amount corresponding to the c value in the composition formula (3) and M ^{2 in} an amount corresponding to a d value is supported as fine particles.

4). The perovskite complex oxide represented by the composition formula (1) described in the above item 1 is converted into Pt.
3. Contact with at least one noble metal vapor selected from the group consisting of Pd, Ir, Rh, Ru, Au, and Ag or an oxide vapor of the noble metal. A method for producing a noble metal-containing perovskite complex oxide represented by a composition formula (2).

5). The composition formula (3) according to claim 3, wherein the noble metal-containing perovskite complex oxide represented by the composition formula (2) described in the above item 2 is heat-treated in a reducing atmosphere. The manufacturing method of the noble metal carrying | support perovskite type complex oxide represented by these.

  Hereinafter, the perovskite complex oxide, the noble metal-containing perovskite complex oxide, and the noble metal-supported perovskite complex oxide of the present invention will be specifically described.

Perovskite complex oxide The perovskite complex oxide of the present invention has the following composition formula (1):
_{(Ba 1-x A x)} BH a O 3-b (1)
(In the formula, A is at least one element selected from the group consisting of a lanthanoid element and an element of Group 2 of the periodic table, and B is an element of Group 3 of the periodic table, an element of Group 4 of the periodic table, and periodic table 13) And at least one element selected from the group consisting of transition metal elements in the fourth period of the periodic table, wherein each symbol of x, a and b represents a numerical value in the following range: 0 ≦ x ≦ 1, 0 <a ≦ 0.5, 0 <b ≦ 0.25).

In the composite oxide represented by the composition formula (1), examples of the lanthanoid element as the A component include La, Ce, Pr, and Nd. Examples of the elements in Group 2 of the periodic table include Ca and Sr. It can be illustrated. The lanthanoid elements and the elements of Group 2 of the periodic table can be used alone or in combination of two or more. Examples of the elements of Group 3 of the periodic table that are B components include Sc and Y. Examples of elements of Group 4 of the periodic table include Ti, Zr, and Hf. Elements of Group 13 of the periodic table include Al. , Ga, In, and the like, and the transition metal element in the fourth period of the periodic table can include Cr, Mn, Fe, Co, Ni, Cu, and the like. The group 3 element of the periodic table, the group 4 element of the periodic table, the group 13 element of the periodic table, and the transition metal element of the 4th period of the periodic table can be used singly or in combination of two or more.

  In the composition formula (1), x is 0 ≦ x ≦ 1, and preferably 0 ≦ x ≦ 0.9. a is 0 <a ≦ 0.5, and preferably 0 <a ≦ 0.3. Further, b is 0 <b ≦ 0.25, and preferably 0 <b ≦ 0.15.

In the composition formula (1), particularly when 0 ≦ x <1, the composite oxide represented by the composition formula (1) contains Ba having high basicity. When heat treatment is performed at a high temperature in contact with the noble metal, Ba and the noble metal react with each other relatively easily to form an alloy, resulting in a lower melting point and a higher pressure (partial pressure) noble metal at a lower temperature. Vapor or noble metal oxide vapor can be generated, and a composite oxide having a high content of noble metal components (M ¹ , M ² ) in the composition formula (2) is expected to be formed.

  In the composition formula (1), when x = 1, Ba is not included, and the perovskite complex oxide represented by the composition formula (1) is represented by the composition formula (2). Both the noble metal-containing perovskite complex oxide and the noble metal-supported perovskite complex oxide obtained by reducing the complex oxide represented by the composition formula (2) are supplied in the air (or to the fuel cell). The reactivity with respect to carbon dioxide present in the fuel) is still lower than that of a compound containing Ba (0 ≦ x <1), and a chemically stable composite oxide which is extremely difficult to produce a carbonate is obtained.

Furthermore, the composite oxide represented by the composition formula (1) has the following formula: t = (r _A + r _O ) / (2 ^1/2 · (r _B + r _O ))
It is necessary that the tolerance factor (t) defined by the following is in the range of 0.9 to 1. In the formula for defining the tolerance factor, r _A is the cation at the A site in the composition formula (1), that is, the arithmetic average of the ionic radii of Ba and A, and r _B is the B site in the composition formula (1). Is an arithmetic average of the ionic radii of B. r 2 _O is the ionic radius of the oxide ion (O ²⁻ ) and is 1.40Å.

The tolerance factor (t) defined by the above formula indicates the degree of distortion of the crystal structure of the perovskite complex oxide. When the tolerance factor is 1, an ideal perovskite structure (cubic system) )it is conceivable that. To calculate the tolerance factor, for example, a paper describing the size of the ion radius (RD Shannon, Acta
Cryst., A32, 751 (1976)) and may be calculated from the above definition formula from the ion radius of each ion.

  In the present invention, it is necessary to use a perovskite complex oxide having a tolerance factor (t) in the range of 0.9 to 1. By using a perovskite complex oxide having such a relatively stable crystal structure, a noble metal-containing perovskite complex oxide containing a noble metal element stably can be obtained, and further, by performing a reduction treatment, a perovskite complex oxide can be obtained. It becomes possible to obtain a noble metal-supported perovskite composite oxide having excellent catalytic performance in which fine particle noble metal is supported on the surface of the composite oxide.

  The composite oxide represented by the composition formula (1) can be obtained by a known method such as a solid phase reaction method or a coprecipitation method. For example, in a solid phase reaction method, a compound containing a metal element included in the above composition formula, for example, an oxide, carbonate, organic substance, or the like is used as a starting material so that the metal element ratio is the same as that of the target oxide. The desired perovskite type complex oxide can be obtained by mixing and baking. The specific firing temperature and firing time are not particularly limited as long as the target composite oxide is formed. For example, firing is performed for about 10 to 40 hours in a temperature range of about 1200 to 1500 ° C. Just do it. In the case where carbonates, organic compounds, or the like are used as the raw material, it is preferable to pre-fire before firing to decompose the raw material, and then fire to form the desired composite oxide. For example, when carbonate is used as the raw material, it may be calcined at about 1000 to 1200 ° C. for about 10 hours and then fired under the above-described conditions. The firing means is not particularly limited, and any means such as an electric heating furnace or a gas heating furnace can be adopted. The firing atmosphere may normally be an oxidizing atmosphere such as in an oxygen stream or in the air. However, when the source material contains a sufficient amount of oxygen, for example, firing may be performed in an inert atmosphere. .

Noble metal-containing perovskite oxide The composite oxide represented by the above composition formula (1) is a vapor of at least one noble metal selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Au, and Ag, or By contacting with the vapor of the noble metal oxide, the following composition formula (2):
(Ba _1-xy A _x M ¹ _y ) (B _1-z M ² _z ) H _a O _3-b (2)
It can be set as the perovskite type complex oxide containing the noble metal element represented by these.

In the composition formula (2), M ¹ and M ² are the same or different and are each at least one element selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Au, and Ag. A and B are the same as in the composition formula (1), A is at least one element selected from the group consisting of a lanthanoid element and a group 2 element of the periodic table, and B is a group 3 of the periodic table And at least one element selected from the group consisting of elements of Group 4 of the periodic table, elements of Group 13 of the periodic table, and transition metal elements of the fourth period of the periodic table.

X is 0 ≦ x ≦ 1, and preferably 0 ≦ x ≦ 0.9. y is 0 ≦ y <0.3, preferably 0 ≦ y ≦ 0.1. z is 0 ≦ z <0.3, and preferably 0 ≦ z ≦ 0.1. However, the sum of y and z is in the range of 0 <y + z <0.6, and particularly preferably 0 <y + z ≦ 0.2. Moreover, a is 0 <a ≦ 0.5, and preferably 0 <a ≦ 0.2. b is 0 <b ≦ 0.25, and preferably 0 <b ≦ 0.1.

  The noble metal-containing perovskite complex oxide represented by the composition formula (2) also needs to have a tolerance factor in the range of 0.9 to 1.

In the composition formula (2), r _A in the definition formula of the tolerance factor is an arithmetic average of the ionic radii of Ba, A and M ¹ , r _B is an arithmetic average of the ionic radii of B and M ² , r 2 _O is the ionic radius of the oxide ion (O ²⁻ ) and is 1.40Å.

  The oxide represented by the composition formula (2) has a perovskite crystal structure in which part of Ba and / or part of B of the composite oxide represented by the composition formula (1) is substituted with a noble metal element. It has a solid solution.

  In the noble metal-containing perovskite complex oxide represented by the composition formula (2), a part of the noble metal element contained in the crystal structure is precipitated on the surface of the complex oxide by the reduction treatment described later, and the particulate noble metal Is supported on the surface of the composite oxide. Such a composite oxide supporting a noble metal is a material having selective oxidizability for carbon monoxide, excellent catalytic activity as a fuel electrode catalyst, and the like.

  The composite oxide represented by the composition formula (2) can be obtained by bringing the composite oxide represented by the composition formula (1) into contact with a noble metal vapor or a noble metal oxide vapor.

  For example, the noble metal or noble metal compound is heated to generate noble metal vapor or noble metal oxide vapor, and the produced vapor is brought into contact with the composite oxide represented by the composition formula (1). ) Can be formed.

  As an example of a specific manufacturing method, for example, the composite oxide represented by the composition formula (1) and the noble metal or noble metal compound are accommodated in the same container, and noble metal vapor or noble metal oxide vapor is contained. By heating to the resulting temperature, the composite oxide can be brought into contact with the noble metal or noble metal oxide vapor. In this case, the reaction vessel may not be completely sealed as long as the vapor of the noble metal or the noble metal oxide can sufficiently come into contact with the composite oxide.

  In such a production method, the shape of the composite oxide represented by the composition formula (1) is not particularly limited. For example, a powdered material may be used, and a porous body obtained by press-molding a powder is used. Alternatively, a sintered body may be used.

  As the noble metal, at least one selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Au and Ag can be used, and in particular, Pt, Pd, Rh, Ir, Ru and the like are preferable. Further, the noble metal compound is a compound containing at least one kind of noble metal selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Au and Ag, and a compound capable of forming an oxide under heat treatment conditions. Can be used. A noble metal oxide may be used. The above-mentioned noble metals and noble metal compounds can be used singly or in combination of two or more.

  The shape of the noble metal and the noble metal compound is not particularly limited, and various shapes of raw materials such as a powdery raw material, a mesh raw material, a linear raw material, and a foil raw material can be used.

In the reaction vessel, vapor of noble metal or noble metal oxide may be in contact with the composite oxide,
The noble metal or noble metal compound used as a raw material and the composite oxide may be in a contact state or in a non-contact state. For example, in a state where the composite oxide represented by the composition formula (1) is placed on the foil-like noble metal component, or in a state where the powdered noble metal component is mixed with the composite oxide of the composition formula (1) A method of heating, a method of heating a precious metal or a precious metal compound and the composite oxide in a non-contact state with an arbitrary interval in the container can be applied.

  In order to allow the reaction to proceed in a shorter time, a noble metal or noble metal oxide vapor having the highest possible pressure (partial pressure) is applied to the composite oxide represented by the composition formula (1) at the highest possible temperature. It is preferable to make it contact. For this purpose, preferably the noble metal foil is brought into contact with the composite oxide powder, more preferably the noble metal mesh is brought into contact with the composite oxide powder, and more preferably, the noble metal or noble metal compound powder is brought into contact with the composite oxide powder. It is desirable that the reaction be performed at a temperature lower than the decomposition temperature of the composite oxide and as close as possible to the decomposition temperature.

  In addition, when heating the composite oxide represented by the composition formula (1) in contact with a noble metal or a noble metal compound, the metal element (Ba, Sr, etc.) contained in the composite oxide is noble metal or noble metal. It is even shorter if it can react with the compound to form an alloy or compound having a lower melting point than the noble metal or noble metal compound and generate a noble metal or noble metal oxide vapor with a higher pressure (partial pressure) at a lower temperature. The reaction can be advanced in time.

The pressure (partial pressure) of the noble metal or noble metal oxide vapor in the container is not particularly limited, but is usually preferably about 10 ⁻³ Pa or more, and more preferably about 1 Pa or more. At this time, the reaction time can be shortened by increasing the pressure (partial pressure) of the noble metal or noble metal oxide vapor.

  The heating temperature may be a temperature at which the noble metal vapor or the noble metal oxide vapor at the pressure described above is generated, and is usually about 800 ° C. or higher and lower than the decomposition temperature of the composite oxide of the composition formula (1). Good. Specifically, the temperature is preferably about 900 to 1750 ° C, and more preferably about 1050 to 1650 ° C.

  Although it does not specifically limit about reaction time, When heating in the above-mentioned temperature range, it is preferable to set it as about 5 to 20 hours, and it is more preferable to set it as about 10 to 15 hours.

In addition, when producing | generating the vapor | steam of a noble metal oxide, what is necessary is just to make oxygen exist in the container which accommodated this complex oxide and a noble metal or a noble metal compound. In this case, the vapor of the noble metal oxide having a predetermined pressure can be generated at a lower temperature than the case of generating the vapor of the noble metal. The partial pressure of oxygen in the container may be about 10 ⁻¹ Pa or more, and preferably about 10 ⁴ Pa or more.

Further, as another example of the manufacturing method, the composite oxide represented by the composition formula (2) is formed also by a method in which an air stream containing noble metal vapor or noble metal oxide vapor is brought into contact with the composite oxide. Can do. In this method, similarly to the above-described method, the pressure (partial pressure) of the noble metal or noble metal oxide vapor is preferably about 10 ⁻³ Pa or more, and more preferably about 1 Pa or more.

Reduction treatment By applying a reduction treatment to the noble metal-containing perovskite complex oxide represented by the above composition formula (2), a part of the noble metal element contained in the crystal structure of the complex oxide is a particulate metal. As a result, it precipitates on the surface of the composite oxide, and the surface of the composite oxide is in a state where fine particulate noble metal is supported.

  As the reduction treatment, for example, heat treatment may be performed in a reducing atmosphere containing hydrogen gas or the like. Specifically, in a hydrogen-containing gas stream such as a hydrogen-inert gas mixed gas containing pure hydrogen gas or an inert gas (such as nitrogen gas) in a range of up to about 100 times the volume of hydrogen gas, 200 to 400 The heat treatment may be performed at about 15 ° C. for about 15 minutes to 1 hour.

The perovskite complex oxide carrying the noble metal after the reduction treatment has the following composition formula (3):
On the surface of the perovskite complex oxide represented by (Ba _{1-xy Ax} M ¹ _yc ) (B _1-z M ² _zd ) H _a O _3-b (3) The noble metal consisting of M ^{1 in} an amount corresponding to the c value in Formula (3) and M ^{2 in} an amount corresponding to the d value is supported as fine particles.

In the composition formula (3), A, B, M ¹ and M ² are the same as those in the composition formula (2). That is, A is at least one element selected from the group consisting of a lanthanoid element and an element of Group 2 of the periodic table, and B is an element of Group 3 of the periodic table, an element of Group 4 of the periodic table, and an element of Group 13 of the periodic table It is at least one element selected from the group consisting of an element and a transition metal element in the fourth period of the element periodic table. M ¹ and M ² are the same or different and are each at least one noble metal element selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Au, and Ag.

  X is 0 ≦ x ≦ 1, and preferably 0 ≦ x ≦ 0.9. y is 0 ≦ y <0.3, preferably 0 ≦ y ≦ 0.1. z is 0 ≦ z <0.3, and preferably 0 ≦ y ≦ 0.1. However, the sum of y and z is in the range of 0 <y + z <0.6, and preferably in the range of 0 <y + z ≦ 0.2.

  c is a value equal to or less than y, and 0 ≦ c <0.1, preferably 0 ≦ c ≦ 0.05. d is a numerical value equal to or less than z, and 0 ≦ d <0.1, preferably 0 ≦ d ≦ 0.05. However, the sum of c and d is 0 <c + d <0.2, and preferably 0 <c + d <0.1.

  a is 0 <a ≦ 0.5, and preferably 0 <a ≦ 0.2. b is 0 <b ≦ 0.25, and preferably 0 <b ≦ 0.1.

  Moreover, the definition formula of the tolerance factor of the composite oxide of the composition formula (3) is the same as that of the composition formula (2), and the value of the tolerance factor is in the range of 0.9-1.

The noble metal deposited on the surface of the composite oxide of the composition formula (3) by the reduction treatment is a part of M ¹ and / or a part of M ² contained in the composite oxide of the composition formula (3).

The particle size of the precious metal fine particles to be deposited varies depending on the conditions of the reduction treatment (hydrogen concentration, temperature, time, etc.), but usually about 10 nm or less for gold, about 500 nm or less for iridium, platinum, palladium, rhodium, ruthenium For silver, it is often about 100 nm or less.

The amount of particulate noble metal supported is, for M ¹ is an amount equivalent to the c value in the formula (3), for M ^2, there in an amount corresponding to d values in the composition formula (3) The total amount is supported on the perovskite complex oxide.

The noble metal-supported perovskite composite oxide in which fine noble metal is supported on the surface of the perovskite composite oxide represented by the composition formula (3) exhibits a unique catalytic activity due to the presence of the fine noble metal. The selective oxidation property of carbon oxide is excellent, and it also has a catalytic activity for hydrogen oxidation. By having such characteristics, the composite oxide subjected to the reduction treatment can exhibit excellent performance as an anode catalyst for a fuel cell having excellent carbon monoxide poisoning resistance.

  The perovskite complex oxide represented by the composition formula (1) and the noble metal-containing perovskite complex oxide represented by the composition formula (2) in the present invention are both in the air (or the fuel supplied to the fuel cell). A chemically stable composite oxide which has a low reactivity with respect to carbon dioxide existing in the middle) and hardly forms carbonates. For example, fine particles on the surface of the perovskite composite oxide represented by the composition formula (3) It is useful as an intermediate for obtaining a noble metal-supported perovskite-type composite oxide on which a noble metal is supported.

  Further, the noble metal-supported perovskite-type composite oxide obtained by reducing the composite oxide represented by the composition formula (2) has a selective oxidation property with respect to carbon monoxide and also has an oxidation activity with respect to hydrogen. Therefore, it is useful as an anode catalyst for a fuel cell having excellent carbon monoxide poisoning resistance.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
Preparation of Perovskite Type Complex Oxide Powder La ₂ O ₃ , SrCO ₃ , BaCO ₃ and Sc ₂ O ₃ are used as raw materials, and these raw materials have an element ratio of La: Sr: Ba: Sc of 0.7: 0.2. : After mixing so as to be 0.1: 1, firing and pulverization were repeated several times in the air, and finally in air at 1400 ° C. for 10 hours to obtain a composition formula: (La _0.7 Sr _{0 .2} Ba _0.1 ) ScH _0.05 O _2.875 to produce a pale yellow oxide powder. The tolerance factor of the composite oxide powder is 0.92. FIG. 1 is an X-ray diffraction pattern of the obtained powder sample, and it was confirmed that a single-phase perovskite complex oxide powder having good crystallinity was obtained.

Preparation of Platinum-Containing Perovskite Type Composite Oxide Powder The tolerance factor (t) obtained by the above method is 0.92 (La _0.7 Sr _0.
2 Ba _0.1 ) ScH _0.05 O _2.875 oxide powder (about 2 g) is placed on a platinum foil (thickness 0.03 mm, weight 1.50 g), and a container with a lid (made of alumina, rectangular parallelepiped, volume: About 30 cm ³ ) and firing in air at 1625 ° C. for 10 hours to obtain a composition formula: (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.994 Pt _0.006 ) H _0. A blue platinum-containing perovskite powder represented by ₀₅ O _2.878 was obtained.

  FIG. 2 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that platinum element was dissolved in the B site in the perovskite crystal lattice. The resulting platinum-containing perovskite powder has a tolerance factor of 0.92.

Reduction treatment of platinum-containing perovskite complex oxide powder (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.994 Pt _0.006 ) H _0.05 O _2.878 obtained by the above method The represented complex oxide was subjected to reduction treatment by heating at 250 ° C. for 1 hour in a gas of 20% hydrogen / 80% argon.

With respect to the product after the reduction treatment, it was confirmed by TEM observation that a part of platinum was precipitated outside the perovskite crystal structure as fine particles having a particle size distribution having a mode value of 10 nm or less. Moreover, it was confirmed by X-ray photoelectron spectroscopy (XPS) measurement that a part of platinum contained in the crystal structure was present as platinum metal particles in the vicinity of the surface. Furthermore, X-ray absorption fine structure (XAFS) measurement confirmed that an amount corresponding to a molar ratio of 1/4 of platinum contained in the crystal structure was present as platinum metal fine particles.

From this result, the product obtained by the above reduction treatment is a product in which a part of platinum in the crystal structure is deposited outside the perovskite crystal structure and exists in the vicinity of the surface in the form of fine particles. La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.994 Pt _0.0048 ) H _0.05 O _2.8756 is included in the crystal structure on the surface of the perovskite complex oxide represented by _2.8756 A pale yellow powder (hereinafter referred to as Pt _0.0) on which platinum fine particles having a molar ratio of 1/4 to platinum are supported.
₀₁₂ / (La _0.7 Sr _0.2 Ba _0.1 ) (represented as Sc _0.994 Pt _0.0048 ) H _0.05 O _2.8756 ).

Catalytic activity of platinum-supported perovskite complex oxide powder Powder sample Pt _0.0012 / (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.994 Pt _0.0048 ) H ₀ obtained by the above method _{For .05} O _2.8756 , the temperature dependence of the catalytic activity (gas conversion rate) for carbon monoxide and hydrogen was measured using a reaction gas containing 1% carbon monoxide or hydrogen in the air. The results are shown in FIG. From FIG. 3, it can be seen that at 180 ° C. (453 K) or higher, the oxidation reaction with respect to carbon monoxide occurs preferentially over the oxidation reaction with respect to hydrogen.

On the other hand, FIG. 4 is a graph showing the temperature dependence of the catalytic activity of a conventionally reported catalyst in which platinum is supported on TiO ₂ . FIG. 4 shows that in the conventional platinum-supported TiO ₂ catalyst, the oxidation reaction with respect to hydrogen occurs preferentially over the oxidation reaction with respect to carbon monoxide.

  From the above results, the powder sample obtained in Example 1 has a selective oxidation property to carbon monoxide, and also has an oxidation activity to hydrogen, and is a fuel cell excellent in carbon monoxide resistance. It can be seen that it can be effectively used as an anode catalyst.

Example 2
Preparation of palladium-containing perovskite complex oxide powder Compositional formula obtained by the same method as in Example 1: (La _0.7 Sr _0.2 Ba _0.1 ) ScH _0.05 O _2.875 Pale yellow oxide powder (approx. 2 g) is placed on palladium foil (thickness 0.05 mm, weight 1.20 g), and a container with a lid (alumina, rectangular parallelepiped, volume: approx. 30 cm ³ )
And calcination in air at 1540 ° C. for 10 hours to obtain a composition formula: (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.981 Pd _0.019 ) H _0.05 O2 _. A light brown palladium-containing perovskite powder represented by ₈₆₅₅ was obtained.

  FIG. 5 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that palladium element was dissolved in the perovskite crystal lattice. The tolerance factor of the obtained palladium-containing perovskite powder is 0.92.

Reduction treatment of palladium-containing perovskite complex oxide powder (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.981 Pd _0.019 ) H _0.05 O _2.8655 obtained by the above method The represented composite oxide was subjected to reduction treatment by heating at 350 ° C. for 1 hour in a gas of 20% hydrogen / 80% argon.

About the product after the reduction treatment, X-ray absorption fine structure (XAFS) measurement confirmed that an amount corresponding to a molar ratio of 1/4 of palladium contained in the crystal structure exists as palladium metal fine particles. It was. From this result, the product obtained by the above reduction treatment is a product in which a part of palladium in the crystal structure is deposited outside the perovskite crystal structure and is present in the vicinity of the surface in the form of fine particles. La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.981 Pd _0.0152 ) H _0.05 O _2.8617 and is included in the crystal structure on the surface of the perovskite complex oxide represented by Pale yellow powder (hereinafter referred to as Pd _0.0038 / (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.981 Pd ₀ ) on which palladium fine particles having a molar ratio of 1/4 to palladium are supported. _0.152 ) H _0.05 O _2.8617 ).

Catalytic activity of palladium-supported perovskite type complex oxide powder Powder sample Pd _0.0038 / (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.981 Pd _0.0152 ) H ₀ obtained by the above method _.05 O _2.8617 was measured for temperature dependence of catalytic activity (gas conversion rate) for carbon monoxide and hydrogen using a reaction gas containing 1% carbon monoxide or hydrogen in the air. The results are shown in FIG. From FIG. 6, it can be seen that at 260 ° C. (533 K) or higher, the oxidation reaction with respect to carbon monoxide occurs preferentially over the oxidation reaction with respect to hydrogen.

  The catalytic activity of palladium reported heretofore is the opposite, and the oxidation reaction for hydrogen preferentially occurs over that for carbon monoxide. Therefore, as shown in FIG. 6, the powder sample obtained in Example 2 has a selective oxidation property against carbon monoxide, and also has an oxidation activity against hydrogen, and has excellent carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 3
Preparation of Iridium-Containing Perovskite Type Composite Oxide Powder A composition formula obtained by the same method as in Example 1 is represented by (La _0.7 Sr _0.2 Ba _0.1 ) ScH _0.05 O _2.875. Pale yellow oxide powder (approx. 0.6 g) is placed on iridium foil (thickness 0.05 mm, weight 0.50 g), put in a container with lid (alumina, rectangular parallelepiped, volume: approx. 30 cm ³ ), air Medium composition at 1625 ° C. for 10 hours to obtain a composition formula: (La _0.
A dark brown iridium-containing perovskite powder represented by ₆₆ Sr _0.19 Ba _0.08 Ir _0.07 ) (Sc _0.93 Ir _0.07 ) H _0.05 O _2.89 was obtained.

  FIG. 7 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that the iridium element was dissolved in the perovskite crystal lattice. The tolerance factor of the obtained iridium-containing perovskite powder is 0.9.

Reduction treatment of iridium-containing perovskite complex oxide powder (La _0.66 Sr _0.19 Ba _0.08 Ir _0.07 ) (Sc _0.93 Ir _0.07 ) H _0.05 O _The composite oxide represented by _2.89 was subjected to reduction treatment by heating in a gas of 20% hydrogen / 80% argon at 400 ° C. for 1 hour.

For the product after the reduction treatment, X-ray absorption fine structure (XAFS) measurement confirmed that an amount corresponding to a 1/4 molar ratio of iridium contained in the crystal structure was present as iridium metal fine particles. It was.

From this result, the product obtained by the above reduction treatment is such that a part of iridium in the crystal structure is deposited outside the perovskite crystal structure and exists in the vicinity of the surface in the form of fine particles. La _0.66 Sr _0.19 Ba _0.08 Ir _0.056 ) (Sc _0.93 Ir _0.056 ) H _0.05 O _2.848 on the surface of the perovskite complex oxide represented by Brown powder carrying iridium fine particles having a molar ratio of 1/4 with respect to iridium contained therein (hereinafter referred to as Ir _0.028 / (La _0.66 Sr _0.19 Ba _0.08 Ir _0.056 ) (Sc _0.93 Ir _0.056 ) H _0.05 O _2.848 ).

Catalyst activity of iridium-supported perovskite complex oxide powder Ir _0.028 / (La _0.66 Sr _0.19 Ba _0.08 Ir _0.056 ) (Sc _0.93 Ir _0.056 ) obtained by the above method For H _0.05 O _2.848 , the temperature dependence of the catalytic activity (gas conversion rate) for carbon monoxide and hydrogen was measured using a reaction gas containing 1% carbon monoxide or hydrogen in the air. . The results are shown in FIG. From FIG. 8, it can be seen that at 275 ° C. (548 K) or higher, the oxidation reaction for carbon monoxide occurs preferentially over the oxidation reaction for hydrogen.

  The previously reported catalytic activity of iridium is the opposite, and the oxidation reaction for hydrogen preferentially occurs over that for carbon monoxide. Therefore, as shown in FIG. 8, the powder sample obtained in Example 3 has a selective oxidation property to carbon monoxide, and also has an oxidation activity to hydrogen, and has excellent carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 4
Production of rhodium-containing perovskite complex oxide powder Compositional formula obtained by the same method as in Example 1: (La _0.7 Sr _0.2 Ba _0.1 ) ScH _0.05 O _2.875 Pale yellow oxide powder (approx. 0.7 g) is placed on rhodium foil (thickness 0.05 mm, weight 0.33 g), and a container with a lid (alumina, rectangular parallelepiped, volume: approx. 30 cm ³
) And calcining in air at 1625 ° C. for 10 hours to obtain a composition formula: (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.937 Rh _0.063 ) H _0.05 O ₂ A black rhodium-containing perovskite powder represented by _.875 was obtained.

  FIG. 9 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that the rhodium element was dissolved in the perovskite crystal lattice. The resulting rhodium-containing perovskite powder has a tolerance factor of 0.93.

Reduction treatment of rhodium-containing perovskite complex oxide powder (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.937 Rh _0.063 ) H _0.05 O _2.875 obtained by the above method The represented complex oxide was subjected to reduction treatment by heating at 400 ° C. for 1 hour in a gas of 20% hydrogen / 80% argon.

The X-ray absorption fine structure (XAFS) measurement of the product after the reduction treatment confirmed that an amount corresponding to a 1/4 molar ratio of rhodium contained in the crystal structure is present as rhodium metal fine particles. It was.

From this result, the product obtained by the above reduction treatment is a product in which a part of rhodium in the crystal structure is deposited outside the perovskite crystal structure and exists in the vicinity of the surface in the form of fine particles. La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.937 Rh _0.0504 ) H _0.05 O _2.8561 Rhodium contained in the crystal structure on the surface of the perovskite complex oxide represented by _2.8561 Brown powder (hereinafter, R
h _0.0126 / (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.937 Rh _0.0504 ) H _0.05 O _2.8561 ) was confirmed.

Catalytic activity of rhodium-supported perovskite complex oxide powder Rh _0.0126 / (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.937 Rh _0.0504 ) H _0.05 obtained by the above method For _O2.8561 , the temperature dependence of the catalytic activity (gas conversion rate) for carbon monoxide and hydrogen was measured using a reaction gas containing 1% carbon monoxide or hydrogen in the air. The results are shown in FIG. FIG. 10 shows that the oxidation reaction for carbon monoxide occurs preferentially over the oxidation reaction for hydrogen at 150 ° C. (423 K) or higher.

  The catalytic activity of rhodium reported heretofore is the opposite, and the oxidation reaction for hydrogen occurs preferentially over that for carbon monoxide. Therefore, as shown in FIG. 10, the powder sample obtained in Example 4 has a selective oxidation property against carbon monoxide, and also has an oxidation activity against hydrogen, and has excellent carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 5
Preparation of gold-containing perovskite complex oxide powder Compositional formula obtained by the same method as in Example 1: (La _0.7 Sr _0.2 Ba _0.1 ) ScH _0.05 O _2.875 Pale yellow oxide powder (about 3.0 g) is placed on a gold foil (thickness 0.03 mm, weight 1.34 g), put in a container with lid (alumina, rectangular parallelepiped, volume: about 30 cm ³ ), By calcining at 1060 ° C. for 100 hours, the composition formula: (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.9998 Au _0.0002 ) H _0.05 O _2.875 A red gold-containing perovskite powder was obtained.

  FIG. 11 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that the gold element was dissolved in the perovskite crystal lattice. The resulting gold-containing perovskite powder has a tolerance factor of 0.92.

Reduction treatment of gold-containing perovskite complex oxide powder (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.9998 Au _0.0002 ) H _0.05 O _2.875 obtained by the above method The represented composite oxide was subjected to reduction treatment by heating at 350 ° C. for 1 hour in a gas of 20% hydrogen / 80% argon.

About the product after the reduction treatment, it is confirmed by X-ray absorption fine structure (XAFS) measurement that an amount corresponding to 1/4 molar ratio of gold contained in the crystal structure exists as gold metal fine particles. It was done.

From this result, the product obtained by the above reduction treatment is such that a part of the gold in the crystal structure is deposited outside the perovskite crystal structure and exists in the vicinity of the surface in the form of fine particles. La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.9998 Au _0.00016 ) H _0.05 O Gold contained in the crystal structure on the surface of the perovskite complex oxide represented by _2.87494 A colorless powder (hereinafter referred to as Au _0.000) on which gold fine particles with a molar ratio of 1/4 are supported.
₀₄ / (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.9998 Au _0.00016 ) H _0.05 O _2.87494 ).

Catalytic activity of gold-supported perovskite complex oxide powder Au _0.00004 / (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.9998 Au _0.00016 ) H _0.05 obtained by the above method For O _2.87494 , the temperature dependence of the catalytic activity (gas conversion rate) with respect to carbon monoxide and hydrogen was measured using a reaction gas containing 1% carbon monoxide or hydrogen in the air. The results are shown in FIG. From FIG. 12, 280 ° C.
Above (553K), it can be seen that the oxidation reaction for carbon monoxide occurs preferentially over the oxidation reaction for hydrogen.

  The catalytic activity of gold reported heretofore is the opposite, and the oxidation reaction for hydrogen occurs preferentially over that for carbon monoxide. Therefore, as shown in FIG. 12, the powder sample obtained in Example 5 has a selective oxidation property to carbon monoxide, and also has an oxidation activity to hydrogen, and is a fuel excellent in carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 6
Preparation of silver-containing perovskite complex oxide powder Compositional formula obtained by the same method as in Example 1: (La _0.7 Sr _0.2 Ba _0.1 ) ScH _0.05 O _2.875 A pale yellow oxide powder (about 3.0 g) is placed on a silver foil (thickness 0.05 mm, weight 1.03 g), placed in a container with a lid (made of alumina, rectangular parallelepiped, volume: about 30 cm ³ ), By calcining at 957 ° C. for 100 hours, the composition formula: (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.998 Ag _0.002 ) H _0.05 O _2.873 A red silver-containing perovskite powder was obtained.

  FIG. 13 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that silver element was dissolved in the perovskite crystal lattice. The tolerance factor of the obtained silver-containing perovskite powder is 0.92.

Reduction treatment of silver-containing perovskite complex oxide powder (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.998 Ag _0.002 ) H _0.05 O _2.873 obtained by the above method The represented composite oxide was subjected to reduction treatment by heating at 350 ° C. for 1 hour in a gas of 20% hydrogen / 80% argon.

The X-ray absorption fine structure (XAFS) measurement of the product after the reduction treatment confirms that an amount corresponding to a 1/4 molar ratio of silver contained in the crystal structure exists as silver metal fine particles. It was done.

From this result, the product obtained by the above reduction treatment is a product in which a part of silver in the crystal structure is deposited outside the perovskite crystal structure and is present in the vicinity of the surface in the form of fine particles. La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.998 Ag _0.0016 ) H _0.05 O Silver contained in the crystal structure on the surface of the perovskite complex oxide represented by _2.8728 Colorless powder (hereinafter referred to as Ag _0.0004 / (
La _0.7 Sr _0.2 Ba _0.1 ) (represented as Sc _0.998 Ag _0.0016 ) H _0.05 O _2.8728 ).

Catalyst activity of silver-supported perovskite complex oxide powder Ag _0.0004 / (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.998 Ag _0.0016 ) H _0.05 obtained by the above method For _O2.8728 , the temperature dependence of the catalytic activity (gas conversion rate) for carbon monoxide and hydrogen was measured using a reaction gas containing 1% carbon monoxide or hydrogen in the air. The results are shown in FIG. From FIG. 14, it can be seen that at 150 ° C. (423 K) or higher, the oxidation reaction with respect to carbon monoxide occurs preferentially over the oxidation reaction with respect to hydrogen.

The catalytic activity of silver reported heretofore is the opposite, and the oxidation reaction for hydrogen occurs preferentially over that for carbon monoxide. Therefore, as shown in FIG. 14, the powder sample obtained in Example 6 has a selective oxidation property against carbon monoxide, and further has an oxidation activity against hydrogen, and has excellent carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 7
Preparation of perovskite type complex oxide powder BaCO ₃ , ZrO ₂ and Y ₂ O ₃ were used as raw materials, and these raw materials were mixed so that the Ba: Zr: Y element ratio was 1: 0.8: 0.2. After that, firing and pulverization were repeated several times in air, and finally, firing in air at 1400 ° C. for 10 hours gave a composition formula: Ba (Zr _0.8 Y _0.2 ) H _0.05 O A pale yellow oxide powder represented by _2.925 was produced.

  The tolerance factor of the composite oxide powder is 0.99. FIG. 15 is an X-ray diffraction pattern of the obtained powder sample, and it was confirmed that a single-phase perovskite complex oxide powder having good crystallinity was obtained.

Preparation of platinum-containing perovskite complex oxide powder Ba (Zr _0.8 Y ₀ ) obtained by the above method and having a tolerance factor (t) of 0.99
_{. 2} ) H _0.05 O _2.925 oxide powder (about 3.3 g) is placed on a platinum foil (thickness 0.05 mm, weight 1.47 g), and a lidded container (alumina, rectangular parallelepiped, volume: about 30 cm) ³ ) and baked in air at 1625 ° C. for 10 hours to obtain a blue color represented by the composition formula: Ba (Zr _0.798 Y _0.198 Pt _0.004 ) H _0.05 O _2.926 A platinum-containing perovskite powder was obtained.

  FIG. 16 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that platinum element was dissolved in the perovskite crystal lattice. The resulting platinum-containing perovskite powder has a tolerance factor of 0.99.

Reduction treatment of platinum-containing perovskite-type composite oxide powder Ba (Zr _0.798 Y _0.198 Pt _0.004 ) H _0.05 O _2.926 obtained by the above-described method, hydrogen 20% / argon 80% gas A reduction treatment was performed by heating at 350 ° C. for 1 hour.

With respect to the product after the reduction treatment, X-ray absorption fine structure (XAFS) measurement confirmed that an amount corresponding to a molar ratio of 1/4 of platinum contained in the crystal structure was present as platinum fine particles. .

From this result, the product obtained by the above reduction treatment is such that a part of platinum in the crystal structure is precipitated out of the perovskite crystal structure and exists in the vicinity of the surface in the form of fine particles. _{(Zr 0.798 Y 0.198 Pt 0.0032)} 1/4 molar ratio with respect to platinum contained in the crystal structure on the surface of the perovskite-type composite oxide represented by _{H 0.05} O _2.9244 It was confirmed that the powder was a pale yellow powder (hereinafter referred to as Pt _0.0008 / Ba (Zr _0.798 Y _0.198 Pt _0.0032 ) H _0.05 O _2.9244 ) on which platinum fine particles were supported. did it.

Catalytic activity of platinum-supported perovskite-type composite oxide powder Pt _0.0008 / Ba (Zr _0.798 Y _0.198 Pt _0.0032 ) H _0.05 O _2.9244 obtained by the above method was used in the air. Using a reaction gas containing 1% carbon monoxide or hydrogen, the temperature dependence of catalytic activity (gas conversion rate) for carbon monoxide and hydrogen was measured. The results are shown in FIG. From FIG. 17, it can be seen that at 175 ° C. (448 K) or higher, the oxidation reaction for carbon monoxide occurs preferentially over the oxidation reaction for hydrogen.

  The catalytic activity of platinum reported heretofore is the opposite, and the oxidation reaction for hydrogen preferentially occurs over that for carbon monoxide. Therefore, as shown in FIG. 17, the powder sample obtained in Example 7 has a selective oxidation property against carbon monoxide, and also has an oxidation activity against hydrogen, and has excellent carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 8
Preparation of Perovskite Type Composite Oxide Powder La ₂ O ₃ , SrCO ₃ , BaCO ₃ and Co ₃ O ₄ are used as raw materials, and these raw materials have an element ratio of La: Sr: Ba: Co of 0.7: 0.2. : After mixing so as to be 0.1: 1, firing and pulverization were repeated several times in air, and finally, firing in air at 1400 ° C. for 5 hours gave a composition formula: (La _0.7 A black oxide powder represented by Sr _0.2 Ba _0.1 ) CoH _0.05 O _2.875 was produced. The tolerance factor of the composite oxide powder is 0.99. FIG. 18 is an X-ray diffraction pattern of the obtained powder sample, and it was confirmed that a single-phase perovskite complex oxide powder having good crystallinity was obtained.

Preparation of platinum-containing perovskite complex oxide powder (La _0.7 Sr ₀ .0) obtained by the above method and having a tolerance factor (t) of 0.99 _.
2 Ba _0.1 ) CoH _0.05 O _2.875 oxide powder (about 2.0 g) is placed on a platinum foil (thickness 0.03 mm, weight 1.25 g), and a container with a lid (made of alumina, rectangular parallelepiped, Volume: about 30cm ³ )
And calcination in air at 1300 ° C. for 10 hours to obtain a composition formula: (La _0.7 Sr _0.2 Ba _0.1 ) (Co _0.996 Pt _0.004 ) H _0.05 O2 _. A dark gray platinum-containing perovskite powder represented by ₈₇₇ was obtained.

  FIG. 19 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that platinum element was dissolved in the perovskite crystal lattice. The resulting platinum-containing perovskite powder has a tolerance factor of 0.99.

Reduction treatment of platinum-containing perovskite complex oxide powder (La _0.7 Sr _0.2 Ba _0.1 ) (Co _0.996 Pt _0.004 ) H _0.05 O _2.877 obtained by the above method Then, reduction treatment was performed by heating at 350 ° C. for 1 hour in a gas of 20% hydrogen / 80% argon.

The X-ray absorption fine structure (XAFS) measurement of the product after the reduction treatment confirmed that an amount corresponding to a molar ratio of 1/4 of platinum contained in the crystal structure exists as platinum metal fine particles. It was.

From this result, the product obtained by the above reduction treatment is a product in which a part of platinum in the crystal structure is deposited outside the perovskite crystal structure and exists in the vicinity of the surface in the form of fine particles. La _0.7 Sr _0.2 Ba _0.1 ) (Co _0.996 Pt _0.0032 ) H _0.05 O Platinum included in the crystal structure on the surface of the perovskite complex oxide represented by _2.8754 Black powder (hereinafter referred to as Pt _0.000) on which platinum fine particles having a molar ratio of 1/4 are supported.
₈ / (La _0.7 Sr _0.2 Ba _0.1 ) (Co _0.996 Pt _0.0032 ) H _0.05 O _2.8754 ).

Catalytic activity of platinum-supported perovskite complex oxide powder Pt _0.0008 / (La _0.7 Sr _0.2 Ba _0.1 ) (Co _0.996 Pt _0.0032 ) H _0.05 obtained by the above method For _O2.8754 , the temperature dependence of the catalytic activity (gas conversion rate) with respect to carbon monoxide and hydrogen was measured using a reaction gas containing 1% carbon monoxide or hydrogen in the air. The results are shown in FIG. From FIG. 20, it can be seen that at 125 ° C. (398 K) or higher, the oxidation reaction with respect to carbon monoxide occurs preferentially over the oxidation reaction with respect to hydrogen.

  The catalytic activity of platinum reported heretofore is the opposite, and the oxidation reaction for hydrogen preferentially occurs over that for carbon monoxide. Therefore, as shown in FIG. 20, the powder sample obtained in Example 8 has a selective oxidation property against carbon monoxide, and also has an oxidation activity against hydrogen, and has excellent carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 9
Preparation of Perovskite Type Composite Oxide Powder Using La ₂ O ₃ , SrCO ₃ and Sc ₂ O ₃ as raw materials, these raw materials are used so that the element ratio of La: Sr: Sc becomes 0.8: 0.2: 1. After being mixed in the mixture, firing and pulverization are repeated several times in the air, and finally, firing in the air at 1400 ° C. for 10 hours results in a composition formula: (La _0.8 Sr _0.2 ) ScH _0.05 O A pale yellow oxide powder represented by _2.925 was produced. The tolerance factor of the composite oxide powder is 0.92. FIG. 21 is an X-ray diffraction pattern of the obtained powder sample, and it was confirmed that a single-phase perovskite complex oxide powder with good crystallinity was obtained.

Preparation of platinum-containing perovskite complex oxide powder (La _0.8 Sr ₀ .0) obtained by the above method and having a tolerance factor (t) of 0.92 _.
2 ) ScH _0.05 O _2.925 oxide powder (about 2 g) is placed on a platinum foil (thickness 0.03 mm, weight 1.50 g), and a container with a lid (alumina, rectangular parallelepiped, volume: about 30 cm ³ ) And is fired in air at 1525 ° C. for 10 hours, and expressed by the composition formula: (La _0.8 Sr _0.2 ) (Sc _0.988 Pt _0.012 ) H _0.05 O _2.931. A blue platinum-containing perovskite powder was obtained.

  FIG. 22 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that platinum element was dissolved in the B site in the perovskite crystal lattice. The resulting platinum-containing perovskite powder has a tolerance factor of 0.92.

Reduction treatment of platinum-containing perovskite-type composite oxide powder (La _0.8 Sr _0.2 ) (Sc _0.988 Pt _0.012 ) H _0.05 O _2.931 obtained by the above method The oxide was reduced in a gas of 20% hydrogen / 80% argon by heating at 350 ° C. for 1 hour.

The X-ray absorption fine structure (XAFS) measurement of the product after the reduction treatment confirmed that an amount corresponding to a molar ratio of 1/4 of platinum contained in the crystal structure exists as platinum metal fine particles. It was. From this result, the product obtained by the above reduction treatment is a product in which a part of platinum in the crystal structure is deposited outside the perovskite crystal structure and exists in the vicinity of the surface in the form of fine particles. La _0.8 Sr _0.2 ) (Sc _0.988 Pt _0.0096 ) H _0.05 O The surface of the perovskite-type composite oxide represented by _2.9262 has platinum with respect to platinum contained in the crystal structure. Pale yellow powder carrying platinum fine particles of 1/4 molar ratio (hereinafter referred to as Pt _0.0
024 / (La _0.8 Sr _0.2 ) (Sc _0.988 Pt _0.0096 ) H _0.05 O _2.9262 ).

Catalytic activity of platinum-supported perovskite complex oxide powder Powder sample Pt _0.0024 / (La _0.8 Sr _0.2 ) (Sc _0.988 Pt _0.0096 ) H _0.05 O ₂ obtained by the above method _.9262 , the temperature dependence of the catalytic activity (gas conversion rate) for carbon monoxide and hydrogen was measured using a reaction gas containing 1% carbon monoxide or hydrogen in the air. The results are shown in FIG. From FIG. 23, it can be seen that at 207 ° C. (480 K) or higher, the oxidation reaction with respect to carbon monoxide occurs preferentially over the oxidation reaction with respect to hydrogen.

  The catalytic activity of platinum reported heretofore is the opposite, and the oxidation reaction for hydrogen preferentially occurs over that for carbon monoxide. Therefore, as shown in FIG. 23, the powder sample obtained in Example 9 has a selective oxidation property against carbon monoxide, and also has an oxidation activity against hydrogen, and has excellent carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 10
Preparation of Palladium-Containing Perovskite Type Composite Oxide Powder A pale yellow oxidation represented by the composition formula: (La _0.8 Sr _0.2 ) ScH _0.05 O _2.925 obtained in the same manner as in Example 9. The product powder (about 2 g) is placed on a palladium foil (thickness 0.05 mm, weight 0.70 g), put in a container with a lid (made of alumina, rectangular parallelepiped, volume: about 30 cm ³ ), and in air at 1540 ° C. for 10 hours. By calcining, a light brown palladium-containing perovskite powder represented by the composition formula: (La _0.8 Sr _0.2 ) (Sc _0.977 Pd _0.023 ) H _0.05 O _2.9135 is obtained. It was.

  FIG. 24 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that palladium element was dissolved in the perovskite crystal lattice. The tolerance factor of the obtained palladium-containing perovskite powder is 0.91.

Reduction treatment of palladium-containing perovskite complex oxide powder (La _0.8 Sr _0.2 ) (Sc _0.977 Pd _0.023 ) H ₀ obtained by the above method
_{. The} composite oxide represented by ₀₅ O _2.9135 was subjected to reduction treatment by heating at 400 ° C. for 1 hour in a 20% hydrogen / 80% argon gas.

About the product after the reduction treatment, X-ray absorption fine structure (XAFS) measurement confirmed that an amount corresponding to a molar ratio of 1/4 of palladium contained in the crystal structure exists as palladium metal fine particles. It was. From this result, the product obtained by the above reduction treatment is a product in which a part of palladium in the crystal structure is deposited outside the perovskite crystal structure and is present in the vicinity of the surface in the form of fine particles. La _0.8 Sr _0.2 ) (Sc _0.977 Pd _0.0184 ) H _0.05 O _2.9089 The surface of the perovskite-type composite oxide is represented by palladium contained in the crystal structure. Pale yellow powder (hereinafter referred to as Pd _0.0046 / (La _0.8 Sr _0.2 ) (Sc _0.977 Pd _0.0184 ) H _0.05 O carrying palladium fine particles with a molar ratio of 1/4 _2.9089 ).

Catalyst activity of palladium-supported perovskite complex oxide powder Powder sample Pd _0.0046 / (La _0.8 Sr _0.2 ) (Sc _0.977 Pd _0.0184 ) H _0.05 O ₂ obtained by the above method _{For .9089} , the temperature dependence of the catalytic activity (gas conversion rate) for carbon monoxide and hydrogen was measured using a reaction gas containing 1% carbon monoxide or hydrogen in the air. The results are shown in FIG. From FIG. 25, it can be seen that at 227 ° C. (500 K) or higher, the oxidation reaction with respect to carbon monoxide occurs preferentially over the oxidation reaction with respect to hydrogen.

  The catalytic activity of palladium reported heretofore is the opposite, and the oxidation reaction for hydrogen preferentially occurs over that for carbon monoxide. Therefore, as shown in FIG. 25, the powder sample obtained in Example 10 has a selective oxidation property against carbon monoxide, and also has an oxidation activity against hydrogen, and has excellent carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 11
Preparation of Perovskite Type Composite Oxide Powder Using La ₂ O ₃ , CaO and Al ₂ O ₃ as raw materials, these raw materials are used so that the element ratio of La: Ca: Al is 0.9: 0.1: 1. After mixing, firing and pulverization are repeated several times in the air, and finally, firing is performed in air at 1600 ° C. for 30 hours, whereby the composition formula: (La _0.9 Ca _0.1 ) AlH _0.025 O ₂ A light red oxide powder represented by _.9625 was produced. The tolerance factor of the composite oxide powder is 1.00. FIG. 26 is an X-ray diffraction pattern of the obtained powder sample, and it was confirmed that a single-phase perovskite complex oxide powder having good crystallinity was obtained.

Preparation of platinum-containing perovskite complex oxide powder (La _0.9 Ca ₀ .0) having a tolerance factor (t) of 1.00 obtained by the above method _.
1 ) AlH _0.025 O _2.9625 oxide powder (about 2 g) is placed on a platinum foil (thickness 0.03 mm, weight 1.50 g), and a container with a lid (alumina, rectangular parallelepiped, volume: about 30 cm ³ ) And baked in air at 1625 ° C. for 20 hours, and expressed by the composition formula: (La _0.9 Ca _0.1 ) (Al _0.9999 Pt _0.0001 ) H _0.025 O _2.96255. A light brown platinum-containing perovskite powder was obtained.

  FIG. 27 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that platinum element was dissolved in the B site in the perovskite crystal lattice. The resulting platinum-containing perovskite powder has a tolerance factor of 1.00.

Reduction treatment of platinum-containing perovskite-type composite oxide powder (La _0.9 Ca _0.1 ) (Al _0.9999 Pt _0.0001 ) H _0.025 O _2.96255 obtained by the above method The oxide was reduced in a gas of 20% hydrogen / 80% argon by heating at 350 ° C. for 1 hour.

The X-ray absorption fine structure (XAFS) measurement of the product after the reduction treatment confirmed that an amount corresponding to a molar ratio of 1/4 of platinum contained in the crystal structure exists as platinum metal fine particles. It was. From this result, the product obtained by the above reduction treatment is a product in which a part of platinum in the crystal structure is deposited outside the perovskite crystal structure and exists in the vicinity of the surface in the form of fine particles. La _0.9 Ca _0.1 ) (Al _0.9999 Pt _0.00008 ) H _0.025 O _2.96251 The surface of the perovskite complex oxide represented by _2.96251 is _compared with platinum contained in the crystal structure. Colorless powder carrying platinum fine particles with a molar ratio of 1/4 (hereinafter referred to as Pt
It was confirmed that it was _0.00002 / (La _0.9 Ca _0.1 ) (Al _0.9999 Pt _0.00008 ) H _0.025 O _2.96251 ).

Catalytic activity of platinum-supported perovskite type complex oxide powder Powder sample Pt _0.00002 / (La _0.9 Ca _0.1 ) (Al _0.9999 Pt _0.00008 ) H _0.025 O ₂ obtained by the above method _{For .96251} , the temperature dependence of the catalytic activity (gas conversion rate) for carbon monoxide and hydrogen was measured using a reaction gas containing 1% carbon monoxide or hydrogen in the air. The results are shown in FIG. From FIG. 28, it can be seen that at 297 ° C. (570 K) or higher, the oxidation reaction with respect to carbon monoxide occurs preferentially over the oxidation reaction with respect to hydrogen.

  The catalytic activity of platinum reported heretofore is the opposite, and the oxidation reaction for hydrogen preferentially occurs over that for carbon monoxide. Therefore, as shown in FIG. 28, the powder sample obtained in Example 11 has a selective oxidation property to carbon monoxide, and also has an oxidation activity to hydrogen, and is a fuel excellent in carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 12
Preparation of Perovskite Type Composite Oxide Powder Using SrCO ₃ , ZrO ₂ and Y ₂ O ₃ as raw materials, the element ratio of Sr: Zr: Y is 1.0: 0.9: 0.1. After being mixed, the firing and pulverization were repeated several times in the air, and finally the firing was performed in air at 1600 ° C. for 10 hours, whereby the composition formula: Sr (Zr _0.9 Y _0.1 ) H _0.05 A light red oxide powder represented by O _2.975 was produced. The tolerance factor of the composite oxide powder is 0.94. FIG. 29 is an X-ray diffraction pattern of the obtained powder sample, and it was confirmed that a single-phase perovskite complex oxide powder having good crystallinity was obtained.

Preparation of platinum-containing perovskite complex oxide powder Sr (Zr _0.9 Y ₀ ) obtained by the above method and having a tolerance factor (t) of 0.94
_{. 1} ) H _0.05 O _2.975 oxide powder (about 2 g) is placed on a platinum foil (thickness 0.03 mm, weight 1.50 g), and a container with a lid (made of alumina, rectangular parallelepiped, volume: about 30 cm ³ ) In the air,
By baking at 1625 ° C. for 10 hours, a blue-green platinum-containing perovskite powder represented by the composition formula: Sr (Zr _0.8988 Y _0.0988 Pt _0.0024 ) H _0.05 O _2.9756 is obtained. It was.

  FIG. 30 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that platinum element was dissolved in the B site in the perovskite crystal lattice. The resulting platinum-containing perovskite powder has a tolerance factor of 0.94.

Reduction treatment of platinum-containing perovskite type complex oxide powder Sr (Zr _0.8988 Y _0.09888 Pt _0.0024 ) H _0.05 O _2.9756 obtained by the above method was treated with hydrogen. Reduction treatment was performed by heating at 350 ° C. for 1 hour in 20% / 80% argon gas.

The X-ray absorption fine structure (XAFS) measurement of the product after the reduction treatment confirmed that an amount corresponding to a molar ratio of 1/4 of platinum contained in the crystal structure exists as platinum metal fine particles. It was. From this result, the product obtained by the above reduction treatment is such that a part of platinum in the crystal structure is deposited outside the perovskite crystal structure and exists in the vicinity of the surface in the form of fine particles. _{(Zr 0.8988} Y _0.0988 Pt _0.00192) on the surface of the _{H 0.05} O _2.97464 perovskite-type complex oxide represented, the molar ratio of 1/4 relative to the platinum contained in the crystal structure Colorless powder carrying platinum fine particles (hereinafter referred to as Pt _0.000).
It was confirmed that a _{48 / Sr (Zr 0.8988 Y 0.0988} Pt 0.00192) represents the _{H 0.05 O 2.97464).}

Catalytic activity of platinum-supported perovskite complex oxide powder Powder sample Pt _0.00048 / Sr (Zr _0.8988 Y _0.09) obtained by the above method
About _{88 Pt 0.00192) H 0.05 O 2.97464} , using 1% carbon monoxide or the reaction gas containing hydrogen into the air, the catalytic activity for carbon monoxide and hydrogen (gas conversion) The temperature dependence was measured. The results are shown in FIG. It can be seen from FIG. 31 that at 157 ° C. (430 K) or higher, the oxidation reaction with respect to carbon monoxide occurs preferentially over the oxidation reaction with respect to hydrogen.

  The catalytic activity of platinum reported heretofore is the opposite, and the oxidation reaction for hydrogen preferentially occurs over that for carbon monoxide. Therefore, as shown in FIG. 31, the powder sample obtained in Example 12 has a selective oxidation property against carbon monoxide, and also has an oxidation activity against hydrogen, and has excellent carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 13
Preparation of perovskite complex oxide powder CaO, ZrO ₂ and Y ₂ O ₃ were used as raw materials, and these raw materials were used so that the element ratio of Ca: Zr: Y was 1.0: 0.95: 0.05. After mixing, firing and pulverization are repeated several times in air, and finally, firing in air at 1350 ° C. for 10 hours is performed, whereby the composition formula: Ca (Zr _0.95 Y _0.05 ) H _0.025 O A light red oxide powder represented by _2.9875 was produced. The tolerance factor of the composite oxide powder is 0.91. FIG. 32 is an X-ray diffraction pattern of the obtained powder sample, and it was confirmed that a single-phase perovskite complex oxide powder having good crystallinity was obtained.

Preparation of platinum-containing perovskite complex oxide powder Ca (Zr _0.95 Y) obtained by the above method and having a tolerance factor (t) of 0.91
_0.05 ) H _0.025 O _2.9875 Oxide powder (approx. 2 g) is placed on a platinum foil (thickness 0.03 mm, weight 1.50 g), and a container with a lid (made of alumina, rectangular parallelepiped, volume: about 30 cm) ³ )
By calcining in air at 1625 ° C. for 10 hours, a light brown platinum-containing perovskite powder represented by the composition formula: Ca (Zr _0.9498 Y _0.0498 Pt _0.0004 ) H _0.025 O _2.9876 was gotten.

  FIG. 33 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that platinum element was dissolved in the B site in the perovskite crystal lattice. The resulting platinum-containing perovskite powder has a tolerance factor of 0.91.

Reduction treatment of platinum-containing perovskite-type composite oxide powder The composite oxide represented by Ca (Zr _0.9498 Y _0.0498 Pt _0.0004 ) H _0.025 O _2.9876 obtained by the above-described method was treated with hydrogen. Reduction treatment was performed by heating at 350 ° C. for 1 hour in 20% / 80% argon gas.

The X-ray absorption fine structure (XAFS) measurement of the product after the reduction treatment confirmed that an amount corresponding to a molar ratio of 1/4 of platinum contained in the crystal structure exists as platinum metal fine particles. It was. From this result, the product obtained by the above reduction treatment is such that a part of platinum in the crystal structure is deposited outside the perovskite crystal structure and exists in the vicinity of the surface in the form of fine particles. (Zr _0.9498 Y _0.0498 Pt _0.00032 ) H _0.025 O _2.98744 The molar ratio of 1/4 to the platinum contained in the crystal structure on the surface of the perovskite complex oxide represented Colorless powder carrying platinum fine particles (hereinafter referred to as Pt _0.00
008 / Ca (represented as Zr _0.9498 Y _0.0498 Pt _0.00032 ) H _0.025 O _2.98744 ).

Catalytic activity of platinum-supported perovskite-type composite oxide powder For the powder sample Pt _0.00008 / Ca (Zr _0.9498 Y _0.0498 Pt _0.00032 ) H _0.025 O _2.98744 obtained by the above method, air Using a reaction gas containing 1% carbon monoxide or hydrogen, the temperature dependence of the catalytic activity (gas conversion rate) for carbon monoxide and hydrogen was measured. The results are shown in FIG. From FIG. 34, it can be seen that at 257 ° C. (530 K) or higher, the oxidation reaction with respect to carbon monoxide occurs preferentially over the oxidation reaction with respect to hydrogen.

  The catalytic activity of platinum reported heretofore is the opposite, and the oxidation reaction for hydrogen preferentially occurs over that for carbon monoxide. Therefore, as shown in FIG. 34, the powder sample obtained in Example 13 has a selective oxidation property to carbon monoxide, and also has an oxidation activity to hydrogen, and has excellent carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 14
Preparation of Ruthenium-Containing Perovskite Type Composite Oxide Powder Compositional formula obtained by the same method as in Example 1: (La _0.7 Sr _0.2 Ba _0.1 ) ScH _0.05 O _2.875 Pale yellow oxide powder (about 2 g) is put in a ceramic container (alumina, rectangular parallelepiped, volume: about 30 cm ³ ), and a ruthenium disk (diameter 13 mm, thickness 1.0 mm) in a non-contact state with this oxide powder. , 1.30 g) was put in the same container, and the container was covered. Next, the composition formula: (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.93 Ru _0.07 ) H _0.05 O _{2.91 is} obtained by firing in air at 1125 ° C. for 10 hours. A yellow-brown ruthenium-containing perovskite powder represented by the formula:

  FIG. 35 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that the ruthenium element was dissolved in the perovskite crystal lattice. The resulting ruthenium-containing perovskite powder has a tolerance factor of 0.93.

Reduction treatment of ruthenium-containing perovskite complex oxide powder (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.93 Ru _0.07 ) H _0.05 O _2.91 obtained by the above method The represented complex oxide was subjected to reduction treatment by heating at 400 ° C. for 1 hour in a gas of 20% hydrogen / 80% argon.

The X-ray absorption fine structure (XAFS) measurement of the product after the reduction treatment confirmed that an amount corresponding to a 1/4 molar ratio of ruthenium contained in the crystal structure exists as ruthenium metal fine particles. It was. From this result, the product obtained by the above reduction treatment is a product in which a part of ruthenium in the crystal structure is deposited outside the perovskite crystal structure and exists in the vicinity of the surface in the form of fine particles. La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.93 Ru _0.056 ) H _0.05 O _2.882 is included in the crystal structure on the surface of the perovskite complex oxide represented by _2.882 Pale yellow-brown powder (hereinafter Ru _0.014 / (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.93 Ru) on which ruthenium fine particles having a molar ratio of 1/4 to ruthenium are supported. _0.056 ) H _0.05 O _2.882 ).

Catalytic activity of ruthenium-supported perovskite complex oxide powder Powder sample Ru _0.014 / (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.93 Ru _0.056 ) H ₀ obtained by the above method _.05 O _2.882 was measured for temperature dependence of catalytic activity (gas conversion rate) with respect to carbon monoxide and hydrogen using a reaction gas containing 1% carbon monoxide or hydrogen in the air. The results are shown in FIG. From FIG. 36, it can be seen that at 147 ° C. (420 K) or higher, the oxidation reaction with respect to carbon monoxide occurs preferentially over the oxidation reaction with respect to hydrogen.

  The catalytic activity of ruthenium that has been reported so far is the opposite, and the oxidation reaction for hydrogen occurs preferentially over that for carbon monoxide. Therefore, as shown in FIG. 36, the powder sample obtained in Example 14 has a selective oxidation property with respect to carbon monoxide, and further has an oxidation activity with respect to hydrogen, and is a fuel excellent in carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

Example 15
Preparation of platinum-containing perovskite complex oxide powder Compositional formula obtained by the same method as in Example 1: (La _0.7 Sr _0.2 Ba _0.1 ) ScH _0.05 O _2.875 Pale yellow oxide powder (about 2 g) is put in a ceramic container (alumina, rectangular parallelepiped, volume: about 30 cm ³ ), and platinum mesh (length: 25 mm in length) is brought into contact with the oxide powder in the container. 2 mm), 10 mm wide, 0.2 mm thick, 80 mesh, weight 1.20 g), and the container was covered. Next, the composition formula: (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.997 Pt _0.003 ) H _0.05 O _{2.8765 is} obtained by firing in air at 1525 ° C. for 10 hours. A blue platinum-containing perovskite powder represented by the following formula was obtained.

  FIG. 37 is an X-ray diffraction pattern of the obtained powder, and it was confirmed that a single-phase perovskite structure having good crystallinity was retained. It was confirmed by X-ray absorption fine structure (XAFS) measurement that platinum element was dissolved in the perovskite crystal lattice. The resulting platinum-containing perovskite powder has a tolerance factor of 0.92.

Reduction treatment of platinum-containing perovskite complex oxide powder (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.997 Pt _0.003 ) H _0.05 O _2.8765 obtained by the above method The represented composite oxide was subjected to reduction treatment by heating at 350 ° C. for 1 hour in a gas of 20% hydrogen / 80% argon.

The X-ray absorption fine structure (XAFS) measurement of the product after the reduction treatment confirmed that an amount corresponding to a molar ratio of 1/4 of platinum contained in the crystal structure exists as platinum metal fine particles. It was. From this result, the product obtained by the above reduction treatment is a product in which a part of platinum in the crystal structure is deposited outside the perovskite crystal structure and exists in the vicinity of the surface in the form of fine particles. La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.997 Pt _0.0024 ) H _0.05 O _2.88753 included in the surface of the perovskite complex oxide represented by the crystal structure Pale yellow powder (hereinafter, referred to as platinum fine particles) having a molar ratio of 1/4 with respect to platinum.
It was confirmed that it was Pt _0.0006 / (La _0.7 Sr _0.2 Ba _0.1 ) (represented as Sc _0.997 Pt _0.0024 ) H _0.05 O _2.8753 ).

Catalytic activity of platinum-supported perovskite complex oxide powder Powder sample Pt _0.0006 / (La _0.7 Sr _0.2 Ba _0.1 ) (Sc _0.997 Pt _0.0024 ) H ₀ obtained by the above method _.05 O _2.8753 was measured for temperature dependency of catalytic activity (gas conversion rate) with respect to carbon monoxide and hydrogen using a reaction gas containing 1% carbon monoxide or hydrogen in the air. The results are shown in FIG. From FIG. 38, it can be seen that at 247 ° C. (520 K) or higher, the oxidation reaction with respect to carbon monoxide occurs preferentially over the oxidation reaction with respect to hydrogen.

The catalytic activity of platinum reported heretofore is the opposite, and the oxidation reaction for hydrogen preferentially occurs over that for carbon monoxide. Therefore, as shown in FIG. 38, the powder sample obtained in Example 15 has a selective oxidation property to carbon monoxide, and also has an oxidation activity to hydrogen, and is a fuel excellent in carbon monoxide poisoning resistance. It turns out that it can utilize effectively as an anode catalyst for batteries.

2 is an X-ray diffraction pattern of the perovskite oxide powder obtained in Example 1. FIG. 2 is an X-ray diffraction pattern of the Pt-containing perovskite oxide powder obtained in Example 1. FIG. 3 is a graph showing the catalytic activity (gas conversion rate) of the Pt-supported perovskite oxide powder obtained in Example 1. The graph which shows the catalyst activity (gas conversion rate) of the titanium oxide which carry | supported Pt. 4 is an X-ray diffraction pattern of the Pd-containing perovskite oxide powder obtained in Example 2. FIG. 3 is a graph showing the catalytic activity (gas conversion rate) of the Pd-supported perovskite oxide powder obtained in Example 2. 4 is an X-ray diffraction pattern of an Ir-containing perovskite oxide powder obtained in Example 3. FIG. 6 is a graph showing the catalytic activity (gas conversion rate) of the Ir-supported perovskite oxide powder obtained in Example 3. Example 4 X-ray diffraction pattern of the Rh-containing perovskite oxide powder obtained. 6 is a graph showing the catalytic activity (gas conversion rate) of the Rh-supported perovskite oxide powder obtained in Example 4. FIG. 6 is an X-ray diffraction pattern of the Au-containing perovskite oxide powder obtained in Example 5. 6 is a graph showing the catalytic activity (gas conversion rate) of the Au-supported perovskite oxide powder obtained in Example 5. FIG. 6 is an X-ray diffraction pattern of an Ag-containing perovskite oxide powder obtained in Example 6. 7 is a graph showing the catalytic activity (gas conversion rate) of the Ag-supported perovskite oxide powder obtained in Example 6. FIG. 6 is an X-ray diffraction pattern of the perovskite oxide powder obtained in Example 7. FIG. 4 is an X-ray diffraction pattern of the Pt-containing perovskite oxide powder obtained in Example 7. 9 is a graph showing the catalytic activity (gas conversion rate) of the Pt-supported perovskite oxide powder obtained in Example 7. FIG. 6 is an X-ray diffraction pattern of a perovskite oxide powder obtained in Example 8. FIG. 6 is an X-ray diffraction pattern of the Pt-containing perovskite oxide powder obtained in Example 8. 9 is a graph showing the catalytic activity (gas conversion rate) of the Pt-supported perovskite oxide powder obtained in Example 8. FIG. 6 is an X-ray diffraction pattern of the perovskite oxide powder obtained in Example 9. 6 is an X-ray diffraction pattern of the Pt-containing perovskite oxide powder obtained in Example 9. FIG. 10 is a graph showing the catalytic activity (gas conversion rate) of the Pt-supported perovskite oxide powder obtained in Example 9. FIG. 6 is an X-ray diffraction pattern of the Pd-containing perovskite oxide powder obtained in Example 10. The graph which shows the catalyst activity (gas conversion rate) of the Pd carrying | support perovskite type oxide powder obtained in Example 10. FIG. FIG. 6 is an X-ray diffraction pattern of the perovskite oxide powder obtained in Example 11. FIG. 4 is an X-ray diffraction pattern of the Pt-containing perovskite oxide powder obtained in Example 11. 10 is a graph showing the catalytic activity (gas conversion rate) of the Pt-supported perovskite oxide powder obtained in Example 11. The X-ray diffraction pattern of the perovskite oxide powder obtained in Example 12. The X-ray diffraction pattern of the Pt-containing perovskite oxide powder obtained in Example 12. The graph which shows the catalyst activity (gas conversion rate) of the Pt carrying | support perovskite type oxide powder obtained in Example 12. FIG. FIG. 7 is an X-ray diffraction pattern of a perovskite oxide powder obtained in Example 13. The X-ray diffraction pattern of the Pt-containing perovskite oxide powder obtained in Example 13. The graph which shows the catalyst activity (gas conversion rate) of the Pt carrying | support perovskite type oxide powder obtained in Example 13. FIG. FIG. 14 is an X-ray diffraction pattern of a Ru-containing perovskite oxide powder obtained in Example 14. 18 is a graph showing the catalytic activity (gas conversion rate) of the Ru-supported perovskite oxide powder obtained in Example 14. 18 is an X-ray diffraction pattern of the Pt-containing perovskite oxide powder obtained in Example 15. FIG. The graph which shows the catalyst activity (gas conversion rate) of the Pt carrying | support perovskite type oxide powder obtained in Example 15

Claims (5)

The following composition formula (1):
_{(Ba 1-x A x)} BH a O 3-b (1)
(In the formula, A is at least one element selected from the group consisting of a lanthanoid element and an element of Group 2 of the periodic table, and B is an element of Group 3 of the periodic table, an element of Group 4 of the periodic table, and periodic table 13) And at least one element selected from the group consisting of transition metal elements in the fourth period of the periodic table, wherein each symbol of x, a and b represents a numerical value in the following range: 0 ≦ x ≦ 1, 0 <a ≦ 0.5, 0 <b ≦ 0.25),
Following formula:
t = (r _A + r _O ) / (2 ^1/2 · (r _B + r _O ))
(Wherein r _A is the arithmetic mean of the ionic radii of Ba and A, r _B is the arithmetic mean of the ionic radii of B, and r _O is the ionic radius of the oxide ion (O ²⁻ ) (1.40Å). The perovskite type complex oxide having a tolerance factor (t) defined in (1) in the range of 0.9 to 1. The following composition formula (2):
(Ba _1-xy A _x M ¹ _y ) (B _1-z M ² _z ) H _a O _3-b (2)
(In the formula, A is at least one element selected from the group consisting of a lanthanoid element and an element of Group 2 of the periodic table, and B is an element of Group 3 of the periodic table, an element of Group 4 of the periodic table, and periodic table 13) And at least one element selected from the group consisting of a group element and a transition metal element in the fourth period of the periodic table, wherein M ¹ and M ² are the same or different and are respectively Pt, Pd, Ir, It is at least one noble metal element selected from the group consisting of Rh, Ru, Au, and Ag, where each symbol of x, y, z, a, and b represents a numerical value in the following range: 0 ≦ x ≦ 1, 0 ≦ y <0.3, 0 ≦ z <0.3, 0 <a ≦ 0.5, 0 <b ≦ 0.25: However, the total value of y and z is 0 <y + z <0.6) Represented by
Following formula:
t = (r _A + r _O ) / (2 ^1/2 · (r _B + r _O ))
(Wherein r _A is the arithmetic mean of the ionic radii of Ba, A and M ¹ , r _B is the arithmetic mean of the ionic radii of B and M ² , and r _O is the oxide ion (O ²⁻ )). A noble metal-containing perovskite complex oxide having a tolerance factor (t) defined by an ionic radius (1.40 Å) in a range of 0.9 to 1. The following composition formula (3):
(Ba _1-xy A _x M ¹ _yc ) (B _1-z M ² _zd ) H _a O _3-b (3) (wherein A is a lanthanoid element and periodic group 2 of the periodic table) At least one element selected from the group consisting of elements, wherein B is an element of Group 3 of the periodic table, an element of Group 4 of the periodic table, an element of Group 13 of the periodic table, and a transition metal of the fourth period of the periodic table And at least one element selected from the group consisting of elements, wherein M ¹ and M ² are the same or different and are at least selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Au, and Ag, respectively. Each of the symbols x, y, z, a, b, c, and d represents a numerical value in the following range: 0 ≦ x ≦ 1, 0 ≦ y <0.3, 0 ≦ z <0. .3, 0 <a ≦ 0.5, 0 <b ≦ 0.25, 0 ≦ c <0.1, 0 ≦ d <0.1; however, the total value of y and z is 0 <y + z <0. In it, c is following numbers y, d is a following values z, the sum of c and d is represented by a 0 <c + d <0.2.),
Following formula:
t = (r _A + r _O ) / (2 ^1/2 · (r _B + r _O ))
(Wherein r _A is the arithmetic mean of the ionic radii of Ba, A and M ¹ , r _B is the arithmetic mean of the ionic radii of B and M ² , and r _O is the oxide ion (O ²⁻ )). On the surface of the perovskite complex oxide having a tolerance factor (t) defined by an ionic radius (1.40 Å) in the range of 0.9 to 1,
A noble metal-supported perovskite-type composite oxide in which a noble metal consisting of M ^{1 in} an amount corresponding to the c value in the composition formula (3) and M ^{2 in} an amount corresponding to a d value is supported as fine particles.   The perovskite complex oxide represented by the composition formula (1) according to claim 1 is vaporized of at least one noble metal selected from the group consisting of Pt, Pd, Ir, Rh, Ru, Au, and Ag. Alternatively, the method for producing a noble metal-containing perovskite complex oxide represented by the composition formula (2) according to claim 2, wherein the noble metal oxide is brought into contact with the vapor of the noble metal oxide.   The composition formula (3) according to claim 3, wherein the noble metal-containing perovskite complex oxide represented by the composition formula (2) according to claim 2 is heat-treated in a reducing atmosphere. The manufacturing method of the noble metal carrying | support perovskite type complex oxide represented by these.

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