JPH11307104A - Electrode catalyst for solid electrolyte type fuel cell and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize sufficient ion conductivity in a low temperature region, suppress solid phase reaction on a boundary surface abutted on a solid electrolyte and provide excellent heat resistance and durability. SOLUTION: This electrode catalyst for a solid electrolyte type fuel cell is perovskite type composite oxide expressed by a rational formula ABCO3 where A is composed of constitutive elements A', A" while B is composed of constitutive elements B', B". Used in this case is an electrode material that contains an oxide-mixed ion conductive material expressed by a general formula A'1-x A"x B'1-y B"y CO3 where A' represents Ce, A" represents Gd and/or Dy, B' represents Sm, B" represents Pt and/or Pd, C represents Mg, and conditions 0<x<=0.5 and 0<y<=0.2 should be satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode catalyst for a solid oxide fuel cell and a method for producing the same, and more particularly to an electrode catalyst for a solid oxide fuel cell which generates electricity using a hydrocarbon liquid fuel or natural gas. The present invention relates to an electrode catalyst for a solid oxide fuel cell using an oxide mixed ion conductive material, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, noble metals such as platinum, rhodium and palladium have been widely used as electrode materials for a solid oxide fuel cell which generates electric power using a hydrocarbon-based liquid fuel or natural gas. Since such a noble metal is used, the cost of these electrodes is high, and the electrode characteristics are deteriorated depending on the use environment. In particular, when used as an electrode catalyst for a solid oxide fuel cell, about 1000
Since it is often used at a temperature around ℃, there is a demand for an electrode material having excellent heat resistance also from the viewpoint of durability. For this reason, use of a perovskite-type composite oxide as an electrode material has been studied.

On the other hand, for example, LaCoO ₃ and LaMn are used as highly active perovskite-type composite oxides.
O ₃ , LaSr _0.8 Mn _0.2 O ₃ , LaGaO _3, etc.
From the National Institute of Materials Technology, the Institute of Engineering of the University of Tokyo, and the Central Research Institute of Electric Power Industry, etc.
7- Tokyo), also from Nippon Telegraph and Telephone Corporation has been proposed an oxide super-ionic conductor material represented by A ₃ B ₂ XO _8, such as, for example, Ba ₃ Sc ₂ ZrO ₈ is (JP-5
-139750).

However, even with the use of these highly active perovskite-type composite oxides, the temperature at which ionic conduction still develops is as high as 800 ° C. or higher, and such highly active perovskite-type composite oxide materials have a higher temperature. By using the zirconia-based or ceria-based solid electrolyte and the perovskite-type composite oxide for a long time in a region or a reducing atmosphere, the resistance of the solid electrolyte / perovskite-type composite oxide interface increases, In such a case, a structural defect occurs due to a partial omission of the fuel cell, and as a result, a problem such as a decrease in power generation efficiency of the fuel cell occurs.

[0005] Therefore, when used as an electrode material for a fuel cell, the electrode catalysis and the electrical conductivity are particularly utilized. At this time, an oxygen ion conductor, that is, an interface between the solid electrolyte and the electrode material is used. It is necessary to reduce separation and the like due to a chemical reaction or thermal stress at the solid electrolyte / electrode material interface while reducing the resistance and securing the adhesion.

[0006]

An object of the invention described in any one of claims 1 to 4 is that an ion conductivity can be exhibited in a low temperature range, and a solid phase reaction at an interface in contact with a solid electrolyte can be achieved. An object of the present invention is to provide an electrode catalyst for a solid oxide fuel cell which suppresses the heat and has excellent heat resistance and durability.

An object of the present invention is to provide a method for efficiently and economically producing the solid oxide fuel cell electrode catalyst of the present invention.

[0008]

According to a first aspect of the present invention, there is provided an electrode catalyst for a solid oxide fuel cell, which is a perovskite-type composite oxide represented by the formula ABCO ₃ , wherein A is A ′ and A ″, B is '' consists constituent elements of the following general formula a and B _'1-x a "B" in _y CO ₃ (wherein, a is Ce, a _"x B' _1-y B is Gd and / or Dy and B ′ are Sm, B ″ is Pt and / or Pd, C is Mg, 0 <x ≦
0.5, 0 <y ≦ 0.2) characterized by using an electrode material containing an oxide mixed ion conductive material represented by the following formula:

The electrode catalyst for a solid oxide fuel cell according to a second aspect is characterized in that, in the electrode catalyst according to the first aspect, the electrode material further contains silica or alumina in addition to the perovskite-type composite oxide. I do.

According to a third aspect of the present invention, there is provided an electrode catalyst for a solid oxide fuel cell, wherein the electrode material comprises 93 to 95% by weight of a perovskite-type composite oxide in the electrode material. .

According to a fourth aspect of the present invention, there is provided an electrode catalyst for a solid oxide fuel cell according to any one of the first to third aspects, wherein an electrode material is applied on the surface of the solid electrolyte substrate. And

According to a fifth aspect of the present invention, there is provided a method for producing an electrode catalyst for a solid oxide fuel cell according to any one of the first to fourth aspects.
The perovskite-type composite oxide is a nitrate of each constituent element of the composite oxide (however, platinum is dinitrodiaminoplatinum,
Palladium is palladium nitrate or dinitrodiaminopalladium), mixed in a stoichiometric ratio, and the mixture is added to an ammonium bicarbonate solution, followed by a hydrothermal reaction in heated steam to form a monooxycarbonate. And then fired in air.

[0013] The method for producing an electrode catalyst for a solid oxide fuel cell according to claim 6 is a method for producing an electrode catalyst for a solid oxide fuel cell according to any one of claims 1 to 4.
A perovskite-type composite oxide is obtained by mixing nitrates of the constituent elements of the composite oxide (however, platinum is dinitrodiaminoplatinum and palladium is dinitrodiaminopalladium) in pure water at a stoichiometric ratio. It is characterized in that the mixture is hydrothermally reacted in heated steam to produce a monooxycarbonate, which is then calcined in air.

[0014] The method for producing an electrode catalyst for a solid oxide fuel cell according to claim 7 is the method for producing an electrode catalyst for a solid oxide fuel cell according to claim 5 or 6, further comprising a perovskite-type composite oxide. After kneading with alumina or silica sol to form a slurry, the slurry is applied to a solid electrolyte substrate, and then sintered in air.

The method for producing an electrode catalyst for a solid oxide fuel cell according to claim 8 is the method for producing an electrode catalyst for a solid oxide fuel cell according to claim 7, wherein the alumina or silica sol is hydrochloride, The concentration of silica is 5 to 8% by weight in the slurry.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The electrode catalyst for a solid oxide fuel cell of the present invention is a perovskite-type composite oxide represented by the formula ABCO ₃ , wherein A is A ′ and A ″, and B is B ′. And B ″, and the following general formula: A ′ _1−x A ″ _x B ′ _1−y B ″ _y CO ₃ (where A is Ce, A ″ is Gd and / or D _y and B ′ are Sm, B ″ is Pt and / or Pd, C is Mg, 0 <x ≦
0.5, 0 <y ≦ 0.2) is used.

The above perovskite-type composite oxide is A '
Is Ce, A "is Gd and / or Dy, B 'is Sm, B"
Is Pt and / or Pd, C is Mg as a sintering aid, and by doping with Mg, a B-site element that contributes significantly to an A-site lattice defect that enhances ion conductivity and an electrode function, particularly It is possible to effectively control the valence of Pt and Pd, enhance the conduction characteristics of the electron-ion mixed conductor, and improve the electrode characteristics.

The substitution amount of the A 'site is 0 <x ≦ 0.5 and is not particularly limited, but it is particularly preferably 0.2 ≦ x ≦ 0.4 for improving the electrode performance.

The substitution amount at the B 'site is 0 <y ≦ 0.2
Although not particularly limited, it is preferable that 0.05 ≦ y ≦ 0.1.

As described above, the valence of the B-site metal is controlled by changing the molar ratio of each metal at the A site of the perovskite-type composite oxide ion conductive material, and as a result, the electronic state is controlled. .

Further, by forming a perovskite structure having lattice defects at the A site, the ability to release and absorb oxygen is improved, so that the internal resistance at the solid electrolyte / electrode catalyst interface is reduced, and the operating temperature can be lowered. In other words, heat resistance and durability are improved by the sintering suppressing effect of the perovskite-type composite oxide itself, and as a result of introducing the lattice defects, it is possible to increase sorbed oxygen generally important for oxygen transfer. it can. The sorbed oxygen is a) α-oxygen:
Desorbed in a wide temperature range of 800 ° C. or less and sorbed in oxygen vacancies generated by partial substitution of A-site ions; and b) β-oxygen: desorbed in a sharp peak around 820 ° C. Some of them correspond to the reduction of atoms to lower atoms, and the presence of these two types of oxygen stabilizes Pt and Pd existing in the crystal structure. The performance is improved.

The perovskite-type composite oxide is contained in the electrode material in a proportion of 91 to 96% by weight, preferably 93 to 95% by weight. By setting the content in such a range, ionic conductivity can be exhibited in a low temperature range, solid phase reaction at an interface in contact with the solid electrolyte can be suppressed, and excellent heat resistance and durability can be obtained.

Further, the electrode material contains alumina or silica in addition to the perovskite-type composite oxide. Alumina or silica has strong adhesion due to a synergistic effect with Mg, which is a sintering aid present in the structure, and has an effect of ensuring stability against heat cycles. The amount is 5 to 10% by weight, preferably 5 to 8% by weight in the electrode material. By setting the amount in such a range, a decrease in the concentration of the perovskite material can be relatively suppressed.

By coating the electrode material containing the perovskite-type composite oxide of the present invention on the surface of a solid electrolyte, an electrode catalyst used for a solid oxide fuel cell can be obtained.

As the solid electrolyte, those conventionally used can be used, for example, yttrium partially stabilized zirconia, ceria and the like.

The first method for producing a perovskite-type composite oxide used for the electrode catalyst for a solid oxide fuel cell of the present invention is a nitrate of each constituent element of the perovskite-type composite oxide (where platinum is dinitrodiaminoplatinum, Palladium is palladium nitrate or dinitrodiaminopalladium), mixed in a stoichiometric ratio, and the mixture is added to an ammonium bicarbonate solution, followed by a hydrothermal reaction in heated steam to form a monooxycarbonate. And then firing in air to obtain a perovskite-type composite oxide.

Specifically, a mixed solution in which Ce nitrate, Gd nitrate and / or Dy nitrate, Sm nitrate, and Mg nitrate are mixed at a stoichiometric ratio of a desired composite oxide is diluted with pure water to about double volume. The dinitrodiaminoplatinum, Pd nitrate or dinitrodiaminopalladium solution thus obtained is added and mixed well with stirring.

The internal pressure of the autoclave is 1.1 kg / cm ²
When the internal pressure reaches 1.1 to 1.
It is adjusted to maintain ² kg / cm 2.
The reaction is continued for about 3 hours, and the reaction is terminated about 0.5 hour after the introduction of steam is no longer necessary. Here, the state in which the introduction of steam is not necessary means a state in which all of them are converted into monooxycarbonate.

The second method for producing a perovskite-type composite oxide used for the electrode catalyst for a solid oxide fuel cell of the present invention is a nitrate of each constituent element of the perovskite-type composite oxide (where platinum is dinitrodiamino acid). Platinum, palladium is dinitrodiaminopalladium) in stoichiometric ratio in pure water, and the mixture is hydrothermally reacted in heated steam to produce monooxycarbonate,
Then, a step of obtaining a perovskite-type composite compound by firing in air is included.

Specifically, Ce, Gd, and / or Dy, Sm, and Mg carbonates are mixed in pure water by stoichiometry of a desired composite oxide, and about double the amount of pure water. The dinitrodiaminoplatinum and dinitrodiaminopalladium solutions diluted in the above are added and mixed well with stirring.

The subsequent steps using ammonium bicarbonate are the same as in the first method.

The obtained perovskite-type composite oxide powder is pulverized and mixed with a hydrochloric acid sol containing 5 to 10% by weight, preferably 5 to 8% by weight of alumina or silica in a slurry by using a planetary ball mill. Obtain a slurry.
Incidentally, it ranged according to the content of alumina or silica is not preferable in a degraded relatively perovskite component and departing from this range, to a hydrochloric acidic CL ^- sintering aid material ions This is because the effect was considered.

Next, the obtained slurry is applied to a solid electrolyte substrate, and then sintered at 850 ° C. in air to prepare an electrode catalyst.

As described above, after the perovskite-type composite oxide and alumina or silica are mixed and pulverized to form a slurry, the slurry is applied to a solid electrolyte substrate and sintered to obtain a slurry.
A synergistic effect with Mg, which is a sintering aid existing in the structure, has strong adhesion, and an electrode catalyst that is stable against a heat cycle caused by starting and stopping the fuel cell can be obtained.

[0035]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 0.9 mol of Ce, 0.1 mol of Gd, 0.95 mol of Sm,
The nitrate of each element was mixed so that Pd was 0.05 mol and Mg was 1.0 mol. That is, cerium nitrate [Ce (N
_{O 3) 3 · 6H 2 O} ] 390.8g, gadolinium nitrate _{[Gd (NO 3) 3 ·} 6H 2 O] 45.1g, samarium nitrate _{[Sm (NO 3) 3 ·} 6H 2 O] 442.2g,
Palladium nitrate [Pd (NO ₃ ) ₂ + H ₂ O] 11.5
g + 11.5 g, magnesium nitrate [Mg (NO ₃ ) ₂
[6H ₂ O] 256.4 g was weighed and mixed with 1 L of pure water, followed by sufficient stirring to obtain a mixed solution.

In an autoclave, 261 g of ammonium hydrogen carbonate [NH ₄ HCO ₃ ] was previously added to 0.5 ml of pure water.
L, and the mixed solution was added with stirring. After the entire amount has been charged, the autoclave is closed, and while continuing stirring, steam having a temperature of about 120 ° C. and a steam pressure of about 2 kg / cm ² is injected into the autoclave, and the internal pressure is 1.1 kg / cm ^2.
When the pressure reached cm ² , the supply of steam was temporarily stopped.

Subsequently, the internal pressure of the autoclave was increased to 1.1 k
g / cm^Two, Maximum 1.2kg / cm ^TwoTo maintain
The reaction was performed while controlling the supply amount of steam. Steam supply open
In 2 hours from the beginning, the internal pressure is 1.1 even if the supply of steam is stopped.
kg / cm^TwoBegan to maintain. In this state, 0.
After continuing the reaction for 5 hours, stop stirring and open the seal.
Was.

The slurry-like hydrate after the completion of the reaction was taken out of the autoclave, and subjected to suction filtration to collect a precipitate.

The collected precipitate was washed with pure water and dried in an oven at 120 ° C. for 12 hours. The obtained dry powder was placed in air at 500 ° C. using an alumina crucible.
For 5 hours to obtain a perovskite-type composite oxide powder. The theoretical composition of the obtained perovskite-type composite oxide is Ce _0.9 Gd _0.1 Sm _0.95 Pd _0.05 MgO ₃ .

The perovskite-type composite oxide powder 10
0 g and 100 g of 8% by weight hydrochloric acid acidic alumina sol (mixed solution of 13 g of boehmite alumina and 87% of 10% by weight hydrochloric acid aqueous solution) were pulverized and mixed for 5 hours using a planetary ball mill (pots and balls are made of agate) and mixed with perovskite type A composite oxide fine powder slurry was obtained.

The obtained slurry was uniformly coated with 6.3 g as an oxide on a 15 cm square yttrium partially stabilized zirconia (shown as YSZ) solid electrolyte substrate.
After drying at 0 ° C. for 12 hours, it was sintered at 1200 ° C. in air to obtain an electrode catalyst substrate A. The amount of Pd used per electrode catalyst A was 85.8 mg, and the amount of Pd used per unit area was 0.8 mg.
38 mg / cm ² .

Example 2 In Example 1, 0.8 mol of Ce, 0.2 mol of Gd,
That is, 347.4 g of cerium nitrate and 9 gadolinium nitrate
A perovskite-type composite oxide Ce _0.8 Gd _0.2 Sm _0.95 Pd _0.05 MgO ₃ was prepared in the same manner except that the amount was 0.3 g, and an electrode catalyst substrate B was obtained in the same manner as in Example 1. The amount of Pd used per electrode catalyst B was 85.
3 mg, and 0.38 mg / c per unit area.
m ² .

Example 3 In Example 1, 0.7 mol of Ce, 0.3 mol of Gd,
That is, 304 g of cerium nitrate, 13 gadolinium nitrate
A perovskite-type composite oxide Ce _0.7 Gd _0.3 Sm _0.95 Pd _0.05 MgO ₃ was prepared in the same manner except that the amount was changed to 5.4 g, and an electrode catalyst substrate C was obtained in the same manner as in Example 1 below. The amount of Pd used per electrode catalyst C was 84.
9 mg, 0.377 mg / unit area.
cm ² .

Example 4 In Example 1, 0.6 mol of Ce, 0.4 mol of Gd,
That is, 260.5 g of cerium nitrate, 1 gadolinium nitrate
A perovskite-type composite oxide Ce _0.6 Gd _0.4 Sm _0.95 Pd _0.05 MgO _{3 was} prepared in the same manner except that the amount was 80.5 g.
Was prepared, and the electrode catalyst substrate D was prepared in the same manner as in Example 1.
I got The amount of Pd used per one electrode catalyst D is 8
4.5 mg, 0.376 m per unit area
g / cm ² .

Example 5 In Example 1, 0.5 mol of Ce, 0.5 mol of Gd,
That is, cerium nitrate 217.1 g, gadolinium nitrate 2
A perovskite-type composite oxide Ce _0.5 Gd _0.5 Sm _0.95 Pd _0.05 MgO _{3 was} prepared in the same manner except that 25.7 g was used.
Was prepared, and the electrode catalyst substrate E was prepared in the same manner as in Example 1.
I got The amount of Pd used per one electrode catalyst D is 8
4.1 mg, 0.374 m per unit area
g / cm ² .

Example 6 In Example 2, 0.9 mol of Sm, 0.1 mol of Pd,
That is, a perovskite-type composite oxide Ce _0.8 Gd _0.2 Sm _0.9 P was prepared in the same manner except that 400.0 g of samarium nitrate and 23 g + 23 g of [palladium nitrate + H ₂ O] were used.
d _0.1 MgO ₃ was prepared, and thereafter, in the same manner as in Example 1,
An electrode catalyst substrate F was obtained. P per one electrode catalyst F
The amount of d used is 171.6 mg, and is 0.76 mg / cm ² per unit area.

[0048]Example 7 In Example 2, 0.85 mol of Sm and 0.15 mol of Pd
377.8 g of samarium nitrate, [palladium nitrate
Um + H_TwoO] 34.6 g + 34.6 g
In this way, the perovskite-type composite oxide Ce_0.8Gd
_0.2Sm_0.85Pd _0.15MgO_ThreeWas prepared, and Example 1 was prepared as follows.
In the same manner as in the above, an electrode catalyst substrate G was obtained. This electrode catalyst G
The amount of Pd used per sheet is 258.9 mg, and the unit is
1.15 mg / cm per area^TwoIt is.

Example 8 In Example 2, 0.8 mol of Sm, 0.2 mol of Pd,
In other words, except that 355.6 g of samarium nitrate and 46.1 g + 46.1 g of [palladium nitrate + H ₂ O] are used, the perovskite-type composite oxide Ce _0.8 Gd _0.2 S
m _0.8 Pd _0.2 MgO ₃ was prepared, and an electrode catalyst substrate H was obtained in the same manner as in Example 1 below. The amount of Pd used per one electrode catalyst H was 347.3 mg, and was 1.54 mg / cm ² per unit area.

Example 9 In Example 2, 0.975 mol of Sm and 0.02 mol of Pd
5 mol, ie 433.3 g of samarium nitrate, dinitrodiaminoplatinum nitric acid solution (Pt = 200 g / kg solution) 2
In the same manner except that 4.5 g + 24.5 g of H ₂ O were used,
Perovskite-type composite oxide Ce _0.8 Gd _0.2 Sm
_0.975 Pt _0.025 MgO ₃ was prepared, and an electrode catalyst substrate I was obtained in the same manner as in Example 1 below. The amount of Pt used per one electrode catalyst I was 77.8 mg, and 0.346 mg / cm ² per unit area.

[0051]Example 10 In Example 2, 0.95 mol of Sm and 0.05 mol of Pt were used.
Samarium nitrate 422.2 g, dinitrodia
Mino platinum nitric acid solution 48.8g + H_TwoO 48.8 g
Except for the above, the perovskite-type composite oxide Ce
_0.8Gd_0.2Sm _0.95Pt_0.05MgO_ThreePrepare the following
An electrode catalyst substrate J was obtained in the same manner as in Example 1. This
The amount of Pt used per electrode catalyst J was 154.4 mg.
0.69 mg / cm per unit area^TwoIn
You.

Example 11 In Example 2, 0.925 mol of Sm and 0.07 Pt were used.
The perovskite-type composite oxide C was prepared in the same manner except that 5 mol, that is, 411.1 g of samarium nitrate and 73.0 g of dinitrodiaminoplatinum nitric acid solution + 73.0 g of H ₂ O were used.
e _0.8 Gd _0.2 Sm _0.925 Pt _0.075 MgO ₃ was prepared, and an electrode catalyst substrate K was obtained in the same manner as in Example 1 below. The amount of Pt used per one electrode catalyst K was 230.
6 mg, and 1.024 mg / unit area.
cm ² .

Example 12 In Example 2, 0.9 mol of Sm, 0.1 mol of Pt,
That is, the perovskite-type composite oxide Ce _0.8 G was prepared in the same manner except that 400.0 g of samarium nitrate and 97.5 g of dinitrodiaminoplatinum nitric acid solution + 97.5 g of H ₂ O were used.
d _0.2 Sm _0.9 Pt _0.1 MgO ₃ was prepared, and an electrode catalyst substrate L was obtained in the same manner as in Example 1 below. The amount of Pt used per sheet of the electrode catalyst L was 306.9 mg, and was 1.364 mg / cm ² per unit area.

Example 13 0.9 mol of Ce, 0.1 mol of Dy, 0.95 mol of Sm,
The nitrate of each metal was mixed so that Pd 0.05 mol and Mg 1.0 mol. That is, cerium nitrate 390.8
g, dysprosium nitrate [Dy (NO _{3) 3} · 5H
₂ O] 43.9 g, samarium nitrate 422.2 g, was mixed with [palladium nitrate + H ₂ O] 11.5 g + 11.5 g, magnesium nitrate 256.4g of pure water 1L, to obtain a sufficiently stirred to a mixed solution .

Hereinafter, in the same manner as in Example 1, the perovskite-type composite oxide Ce _0.9 Dy _0.1 Sm _0.95 Pd _0.05 Mg
O ₃ was prepared, and an electrode catalyst substrate M was obtained in the same manner as in Example 1 below using the obtained composite oxide powder. The amount of Pd used per one electrode catalyst M was 85.6 mg,
It is 0.38 mg / cm ² per unit area.

Example 14 A perovskite-type composite oxide Ce _0.8 Dy was prepared in the same manner as in Example 13, except that 0.8 mol of Ce and 0.2 mol of Dy were used, ie, 347.4 g of cerium nitrate and 87.7 g of dysprosium nitrate. _0.2 Sm _0.95 Pd _0.05 Mg
O ₃ was prepared, and an electrode catalyst substrate N was obtained in the same manner as in Example 1. The amount of Pd used per N of this electrode catalyst was 85.0 mg, and 0.378 m per unit area.
g / cm ² .

Example 15 A perovskite-type composite oxide Ce _0.7 Dy _0.3 Sm was prepared in the same manner as in Example 13, except that Ce was _0.7 mol and Dy was _0.3 mol, that is, 304 g of cerium nitrate and 131.6 g of dysprosium nitrate were used. _0.95 Pd _0.05 MgO
₃ was prepared, and an electrode catalyst substrate O was obtained in the same manner as in Example 1 below. The amount of Pd used per one electrode catalyst O is 8
4.5 mg, 0.376 mg per unit area
/ Cm ² .

[0058]Example 16 In Example 13, Ce 0.6 mol, Dy 0.4
Cerium nitrate, 260.5 g, dysprosium nitrate
Perovska in the same manner except that
Ite-type composite oxide Ce_0.6Dy_0.4Sm_0.95Pd_0.05M
gO_ThreeWas prepared in the same manner as in Example 1 below.
A substrate P was obtained. Pd usage per electrode catalyst P
Is 84.0 mg and 0.373 per unit area
mg / cm ^TwoIt is.

[0059]Example 17 In Example 13, 0.5 mol of Ce, 0.5 mol of Dy
217.1 g of cerium nitrate, dysprosium nitrate
Perovska in the same manner except that the amount is 219.3 g.
Ite-type composite oxide Ce_0.5Dy_0.5Sm_0.95Pd_0.05M
gO_ThreeWas prepared in the same manner as in Example 1 below.
A substrate Q was obtained. Pd usage per electrode catalyst Q
Is 83.5 mg and 0.371 per unit area
mg / cm ^TwoIt is.

[0060]Example 18 In Example 14, 0.9 mol of Sm and 0.1 mol of Pd
400 g of samarium nitrate [palladium nitrate +
H_TwoO] 23 g + 23 g
Skye type composite oxide Ce_0.8Dy_0.2Sm_0.9Pd
_0.1MgO_ThreeWas prepared in the same manner as in Example 1.
An electrode catalyst substrate R was obtained. Pd per electrode catalyst R
The usage amount is 171 mg, and 0.7 per unit area.
6mg / cm ^TwoIt is.

[0061]Example 19 In Example 14, 0.85 mol of Sm and 0.15 Pd
Moles, ie, 377.8 g of samarium nitrate,
Jium + H_TwoO] The same except that it is 34.6 g + 34.6 g
In this way, the perovskite-type composite oxide Ce_0.8Dy
_0.2Sm_0.85Pd _0.15MgO_ThreeWas prepared, and Example 1 was prepared as follows.
In the same manner as in the above, an electrode catalyst substrate S was obtained. This electrode catalyst S
The amount of Pd used per sheet is 258.2mg, unit
1.15mg / cm per area^TwoIt is.

Example 20 The procedure of Example 14 was repeated except that 0.8 mol of Sm and 0.2 mol of Pd were used, that is, 355.6 g of samarium nitrate and 46.1 g + 46.1 g of [palladium nitrate + H ₂ O]. Complex oxide Ce _0.8 Dy _0.2
Sm _0.8 Pd _0.2 MgO ₃ was prepared, and an electrode catalyst substrate T was obtained in the same manner as in Example 1 below. The amount of Pd used per one electrode catalyst T was 346.3 mg, and was 1.54 mg / cm ² per unit area.

[0063]Example 21 In Example 14, 0.975 mol of Sm, Pt0.0
25 moles, ie 433.3 g of samarium nitrate, [dini
Tridiaminoplatinum nitric acid solution (Pt = 200g / kg
Liquid) + H_TwoO] Same as above except 24.5 g + 24.5 g
And the perovskite-type composite oxide Ce_0.8Dy_0.2
Sm_0.975Pt_0.025MgO_ThreeWas prepared, and Example 1 was prepared as follows.
In the same manner as in the above, an electrode catalyst substrate U was obtained. This electrode catalyst U
Pt usage per sheet is 77.6mg, unit surface
0.345mg / cm per product ^TwoIt is.

Example 22 In Example 14, 0.95 mol of Sm and 0.05% of Pt were used.
Mol, ie, 422.2 g of samarium nitrate, 48.8 g of dinitrodiaminoplatinum nitric acid solution + H ₂ O + 48.8 g
In the same manner except that the g, a perovskite-type composite oxide _{Ce 0.8 Dy 0. 2 Sm 0.95 Pt} 0.05 MgO 3 was prepared,
Thereafter, in the same manner as in Example 1, an electrode catalyst substrate V was obtained. The amount of Pt used per one electrode catalyst V was 154 mg, and 0.684 mg / cm ² per unit area.

Example 23 In Example 14, 0.925 mol of Sm and 0.0% of Pt were used.
75 mol, that is, 411.1 g of samarium nitrate, 73.0 g of [dinitrodiaminoplatinum nitric acid solution + H ₂ O] +7 g
A perovskite-type composite oxide Ce _0.8 Dy _0.2 Sm _0.925 Pt _0.075 MgO _{3 was} prepared in the same manner except that the amount was 3.0 g.
Was prepared, and the electrode catalyst substrate W was formed in the same manner as in Example 1.
I got The amount of Pt used per electrode catalyst W is 22
9.8 mg, 1.02 mg / unit area
cm ² .

Example 24 In Example 14, 0.9 mol of Sm and 0.1 mol of Pt, that is, 400.0 g of samarium nitrate, [dinitrodiaminoplatinic nitric acid solution + H ₂ O] 97.5 g + 97.5 g
Perovskite-type composite oxide C
The _{e 0.8 Dy 0.2 Sm 0.9 Pt 0.1} MgO 3 was prepared, in the same manner as in Example 1, to obtain an electrode catalyst substrate X. The amount of Pt used per electrode catalyst X was 306.1 mg, and was 1.36 mg / cm ² per unit area.

Example 25 An electrode catalyst substrate Y was obtained in the same manner as in Example 1 except that 100 g of hydrochloric acid acidic silica sol containing 6% by weight of Si was used. The amount of Pd used per one electrode catalyst Y was 87.1 mg, and 0.387 m per unit area.
g.

Comparative Example 1 Ce 0.8 mol, Gd 0.2 mol, Sm 1.0 mol, M
1.0 mol, i.e., 347.4 g of cerium nitrate, 90.3 g of gadolinium nitrate, 44.4 g of samarium nitrate,
After mixing 256.4 g of magnesium nitrate with 1 L of pure water, the mixture was sufficiently stirred to obtain a mixed solution.

In advance, 261 g of ammonium hydrogen carbonate was dissolved in 0.5 L of pure water in an autoclave, and a steam mixed solution was charged with stirring. After the entire amount has been charged, the autoclave is closed, and stirring is continued at 120 ° C., 2 kg / c.
m ² of steam were injected. Autoclave internal pressure is 1.1k
When the g / cm ² was reached, the supply of steam was temporarily stopped.

Subsequently, the internal pressure of the autoclave was reduced to 1.1 k
g / cm^Two, Maximum 1.2kg / cm ^TwoTo maintain
The reaction was performed while controlling the supply amount of steam. Steam supply open
The internal pressure is 1.1k in 2 hours from the beginning even if the supply of steam is stopped
g / cm^TwoBegan to maintain. 0.5 in this state
After continuing the reaction for a period of time, stop stirring, open the seal and
Was.

The slurry-like hydrate after the completion of the reaction was taken out of the autoclave and subjected to suction filtration to collect a precipitate. After washing the collected precipitate with pure water,
Dried in oven at 12 ° C. for 12 hours. The dried powder is calcined in air at 500 ° C. for 5 hours using an alumina crucible,
A perovskite-type composite oxide powder was obtained. The theoretical composition of the obtained perovskite-type composite oxide is Ce _0.8 Gd _0.2
SmmgO ₃ .

To the obtained perovskite-type composite oxide powder, 0.05 mol of Pd, that is, 11.5 g of palladium nitrate was added.
Was dissolved in 100 ml of pure water, mixed thoroughly, dried in an oven at 120 ° C. for 3 hours, and dried in air.
By baking at 00 ° C. for 2 hours, a Pd-supported perovskite-type composite oxide powder was obtained.

100 g of the Pd-supported perovskite-type composite oxide powder and 100 g of 8% by weight hydrochloric acid acidic alumina sol
And pulverized and mixed for 5 hours using a planetary ball mill,
A supported perovskite-type composite oxide fine powder slurry was obtained. The obtained slurry was uniformly coated with 6.3 g as an oxide on a 15 cm square YSZ solid electrolyte substrate,
After drying at 0 ° C. for 12 hours, sintering was performed at 850 ° C. in the air to obtain an electrode catalyst substrate a. The amount of Pd used per sheet of the electrode catalyst a was 83.5 mg, and the amount of Pd used per unit area was 0.5 mg.
371 mg / cm ² .

Comparative Example 2 In Comparative Example 1, 0.8 mol of Ce, 0.2 mol of Dy,
That is, a perovskite-type composite oxide Ce _0.8 Dy _0.2 SmmgO ₃ was prepared in the same manner except that 347.4 g of cerium nitrate and 87.7 g of dysprosium nitrate were used. Prepare a supported perovskite-type composite oxide powder, using this powder,
An electrode catalyst substrate b was obtained in the same manner as in Comparative Example 1. The amount of Pd used per one electrode catalyst b was 83.3 mg, and the output per unit area was 0.37 mg / cm ² .

[0075]Comparative Example 3 Perovskite-type composite oxide Ce obtained in Comparative Example 1
_0.8Gd_0.2SmmgO _ThreeUsing powder, Comparative Example 1
After slurrying in the same manner, the solid electrolyte substrate made of YSZ
The resultant was applied and sintered to obtain an electrode catalyst substrate c. This electrode catalyst
c does not contain Pd.

Tables 1 and 2 show the composition of the perovskite-type composite oxide used for the electrode catalysts obtained in Examples 1 to 24 and Comparative Examples 1 to 3 and the composition amount per obtained electrode catalyst cell, respectively. Shown in

[0077]

[Table 1]

[0078]

[Table 2]

Test Example 1 (Evaluation of electromotive force) The electromotive force of each of the perovskite-type composite oxide electrode catalysts obtained in Examples 1 to 24 and Comparative Examples 1 to 3 was measured. Specifically, Examples 1 to 24
The temperature at which the electromotive force of the noble metal element-containing perovskite-type composite oxide obtained by the above and the conventional perovskite-type composite oxide matches the theoretical electromotive force according to the Nerunst equation is defined as an operation start temperature TNe (° C.). , The TNe
(° C.), the characteristics of each electrode catalyst as an electrode were evaluated. The characteristic evaluation was obtained by measuring the electromotive force when latm oxygen was passed through the reference electrode and 10% O ₂ -N ₂ gas was passed through the measurement electrode. FIG. 1 shows a schematic diagram of the evaluation cell, and Table 3 shows the evaluation results.

[0080]

[Table 3]

Test Example 2 (Evaluation of endurance) Electrode catalysts B, F, J, N, obtained in Examples 2, 6, 10, 14, 18, 22 and Comparative Examples 1, 2
R, V and a, b, 1200 ° C in air atmosphere
For 5 hours, the electromotive force was measured in the same manner as in Test Example 1, and the change in the operation start temperature was determined. Table 4 shows the obtained results.

[0082]

[Table 4]

In Comparative Examples 1 and 2 in which Pd was supported on the composite oxide, Pd crystal particles grew due to heat, and Pd
Although it operates at a lower temperature than the perovskite-type composite oxide that does not support d, the operation start temperature is significantly deteriorated as compared with the electrode catalysts of the examples of the present invention in which Pd is incorporated in the crystal structure. I understand.

[0084]

The electrode catalyst for a solid oxide fuel cell according to any one of claims 1 to 4 can effectively control the valence of a B-site element which contributes significantly to the electrode action. Thus, the conduction characteristics of the electron-ion mixed conductor can be enhanced, and the electrode characteristics can be improved. Further, the solid-state reaction between the solid electrolyte and the solid electrolyte in contact with the perovskite-type composite oxide is suppressed, and the perovskite-type composite oxide containing a noble metal having durability and heat resistance enables low-temperature operation of the solid oxide fuel cell. Becomes possible.

Therefore, the necessity of using a high heat-resistant material for stacking, which was considered in the conventional temperature-lowering solid electrolyte fuel cell, is eliminated, and the cost can be reduced by using inexpensive materials. The system can be recalled and put into practical use, and the use of alternative fuels and high costs such as environmental protection can be expected.

The method for producing an electrode catalyst for a solid oxide fuel cell according to any one of claims 5 to 8 can efficiently and economically use such an electrode catalyst for a solid oxide fuel cell of the present invention. Can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic view of a cell for evaluating an electromotive force of an electrode catalyst for a solid oxide fuel cell according to the present invention.

Claims (8)

[Claims] 1. A perovskite-type composite oxide represented by the chemical formula ABCO ₃ , wherein A is A ′ and A ″, and B is B ′.
"It consists constituent elements of the following general formula A and B" in the _y CO ₃ (wherein, A is _{Ce, A "'1-x}A" x B' 1-y B is Gd and / or Dy, B ' Is Sm, B ″ is Pt and / or Pd, C is Mg, 0 <x ≦
0.5, 0 <y ≦ 0.2). An electrode catalyst for a solid oxide fuel cell, comprising an electrode material containing an oxide mixed ion conductive material represented by the following formula: 2. The electrode catalyst for a solid oxide fuel cell according to claim 1, wherein the electrode material further contains silica or alumina in addition to the perovskite-type composite oxide. 3. The catalyst according to claim 1, wherein a perovskite-type composite oxide is contained in the electrode material.
An electrode catalyst for a solid oxide fuel cell, comprising 95% by weight. 4. The electrode catalyst for a solid oxide fuel cell according to claim 1, wherein an electrode material is applied on a surface of the solid electrolyte substrate. 5. In producing the electrode catalyst for a solid oxide fuel cell according to any one of claims 1 to 4, the perovskite-type composite oxide comprises a nitrate of each constituent element of the composite oxide (however, platinum Is dinitrodiaminoplatinum, palladium is palladium nitrate or dinitrodiaminopalladium) in a stoichiometric ratio, and the mixture is added to an ammonium hydrogen carbonate solution, followed by a hydrothermal reaction in heated steam. A method for producing an electrode catalyst for a solid oxide fuel cell, wherein a monooxycarbonate is produced and then calcined in air. 6. In producing the electrode catalyst for a solid oxide fuel cell according to any one of claims 1 to 4, the perovskite-type composite oxide comprises a nitrate of each constituent element of the composite oxide (however, platinum Is dinitrodiaminoplatinum and palladium is dinitrodiaminopalladium) in pure water at a stoichiometric ratio, and the mixture is hydrothermally reacted in heated steam to produce a monooxycarbonate. A method for producing an electrode catalyst for a solid oxide fuel cell, characterized in that the electrode catalyst is obtained by firing in an atmosphere. 7. The method for producing an electrode catalyst for a solid oxide fuel cell according to claim 5, wherein the perovskite-type composite oxide is kneaded with alumina or silica sol to form a slurry, and then the slurry is solidified. A method for producing an electrode catalyst for a solid oxide fuel cell, which is applied to an electrolyte substrate and then sintered in air. 8. The method for producing an electrode catalyst for a solid oxide fuel cell according to claim 7, wherein the alumina or silica sol is hydrochloride, and the concentration of alumina or silica is 5 to 8% by weight in the slurry. A method for producing an electrode catalyst for a solid oxide fuel cell.