WO2015173881A1

WO2015173881A1 - Hydrogen-generating catalyst, and exhaust gas purification catalyst

Info

Publication number: WO2015173881A1
Application number: PCT/JP2014/062667
Authority: WO
Inventors: 伊藤　淳二; 花木　保成; 哲郎内藤
Original assignee: 日産自動車株式会社
Priority date: 2014-05-13
Filing date: 2014-05-13
Publication date: 2015-11-19

Abstract

This hydrogen-generating catalyst comprises: a noble metal; an oxide which supports the noble metal, and which includes lanthanum (La) and zirconium (Zr); and an oxygen occlusion/release material. This exhaust gas purification catalyst includes: a first catalyst unit comprising a noble metal, and an oxide which supports the noble metal, and which includes lanthanum (La) and zirconium (Zr); a second catalyst unit comprising the oxygen occlusion/release material; and a holding material which holds the first catalyst unit and the second catalyst unit in a state of being separated from each other.

Description

Hydrogen production catalyst and exhaust gas purification catalyst

The present invention relates to a hydrogen generation catalyst, an exhaust gas purification catalyst, and an exhaust gas purification monolith catalyst.
More specifically, the present invention relates to a hydrogen generation catalyst having excellent hydrogen generation performance, an exhaust gas purification catalyst using the same, and an exhaust gas purification monolith catalyst.

Conventionally, in order to reduce the load on the environment, harmful substances such as hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx) contained in the exhaust gas discharged from the internal combustion engine of the vehicle are removed. Exhaust gas purifying catalysts in which a noble metal such as platinum (Pt) is supported on a metal oxide carrier such as aluminum oxide (Al ₂ O ₃ ) are widely used.
Further, an exhaust gas purification device for purifying harmful substances in the exhaust gas is usually installed in the exhaust system of the internal combustion engine.

In the exhaust gas purification apparatus, an exhaust gas purification catalyst using a noble metal is usually used. However, since the noble metal is expensive, a reduction in the amount of use is required from the viewpoint of cost reduction.
Among noble metals, rhodium (Rh), which exhibits high purification activity with respect to nitrogen oxides (NOx), is particularly expensive, and thus a reduction in the amount of use is particularly demanded.

Conventionally, in exhaust gas purification catalysts using aluminum oxide (Al ₂ O ₃ ) or cerium (Ce) -containing oxide as the main component of the catalyst carrier, rhodium (Rh) is aluminum oxide (Al ₂ O ₃ ). It is known that deterioration with time occurs, such as solid solution in the solution or rhodium (Rh) is coated with a cerium (Ce) -containing oxide.
In this case, since the nitrogen oxide (NOx) purification performance of the exhaust gas purification catalyst is lowered, it is necessary to increase the amount of rhodium (Rh) used in advance in order to compensate for the reduced performance.

On the other hand, a hydrocarbon reforming catalyst in which rhodium (Rh) is supported on a composite oxide containing lanthanum (La) and zirconium (Zr) has been proposed (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2002-126522

However, due to concerns about resource depletion, further reduction in the amount of noble metal used is required. In the hydrocarbon reforming catalyst described in Patent Document 1, the reaction rate at the active site is not sufficient, and nitrogen oxides ( There has been a problem that the purification efficiency of NOx) is greatly reduced.

The present invention has been made in view of such problems of the conventional technology. An object of the present invention is to provide a hydrogen generation catalyst having excellent hydrogen generation performance, an exhaust gas purification catalyst and an exhaust gas purification monolith catalyst using the same.

The inventors of the present invention made extensive studies to achieve the above object. As a result, the inventors have found that the above object can be achieved by supporting a noble metal on an oxide containing lanthanum (La) and zirconium (Zr), and further coexisting this with an oxygen storage / release material, thereby completing the present invention. It came to.

That is, the hydrogen generation catalyst of the present invention comprises a noble metal, an oxide containing lanthanum (La) and zirconium (Zr) supporting the noble metal, and an oxygen storage / release material.

The exhaust gas purifying catalyst of the present invention includes a first catalyst unit comprising a noble metal and an oxide containing lanthanum (La) and zirconium (Zr) supporting the noble metal, and a second catalyst comprising an oxygen storage / release material. A unit and a holding material that holds the first catalyst unit and the second catalyst unit in a separated state are contained.

Furthermore, the exhaust gas purification monolith catalyst of the present invention is such that a catalyst layer containing the exhaust gas purification catalyst of the present invention is formed in the exhaust gas flow path of the monolith carrier.

According to the present invention, it is configured to include a noble metal, an oxide containing lanthanum (La) and zirconium (Zr) supporting the noble metal, and an oxygen storage / release material.
Therefore, it is possible to provide a hydrogen generation catalyst having excellent hydrogen generation performance, an exhaust gas purification catalyst using the same, and an exhaust gas purification monolith catalyst.

FIG. 1 is an explanatory diagram showing a reaction in a hydrogen generation catalyst. FIG. 2 is an explanatory view showing a mitigation mechanism of carbon monoxide (CO) adsorption poisoning. FIG. 3 is a graph showing the results of measuring the state of rhodium (Rh) supported on an oxide in the hydrogen generation catalyst of each example by X-ray photoelectron spectroscopy (XPS). FIG. 4 is a graph showing the production entropy per oxygen atom of various oxides. FIG. 5 is an explanatory diagram showing the interaction between a specific additive element (M) and carbon monoxide (CO). FIG. 6 is an explanatory view showing a monolith catalyst for exhaust gas purification according to the third embodiment of the present invention. FIG. 7 is an explanatory diagram showing a measurement program for a carbon monoxide shift reaction test. FIG. 8 is an explanatory view showing the catalyst arrangement in the NOx emission amount measurement.

Hereinafter, a hydrogen generation catalyst according to an embodiment of the present invention, an exhaust gas purification catalyst using the same, and an exhaust gas purification monolith catalyst will be described in detail.

(First embodiment)
First, the hydrogen generation catalyst according to the first embodiment of the present invention will be described in detail.
The hydrogen generation catalyst of the present embodiment is composed of a noble metal, an oxide containing lanthanum (La) and zirconium (Zr) supporting the noble metal, and an oxygen storage / release material.

As described above, a noble metal such as platinum (Pt), rhodium (Rh), palladium (Pd) is supported on an oxide containing lanthanum (La) and zirconium (Zr), and the oxygen storage / release material coexists. By making it, it will have the outstanding hydrogen production performance.
Further, when such a hydrogen generation catalyst is applied to an exhaust gas purification catalyst, the generated hydrogen (H ₂ ) acts as a NOx reducing agent, and the NOx purification rate can be improved.

The reason for having excellent hydrogen generation performance is that a noble metal such as rhodium (Rh) is supported on an oxide containing lanthanum (La) and zirconium (Zr), and this and an oxygen storage / release material coexist. This is thought to be because carbon monoxide (CO) adsorption poisoning produced in the form of carbon dioxide, which is a reaction product of the carbon monoxide shift reaction, which causes a decrease in hydrogen production performance, is alleviated.

FIG. 1 is an explanatory diagram showing a reaction in a hydrogen generation catalyst. FIG. 1A is an explanatory diagram showing a reaction when the oxygen storage / release material coexists, and FIG. 1B is an explanatory diagram showing a reaction when the oxygen storage / release material does not coexist.
As shown in FIG. 1B, in the case where the oxygen storage / release material does not coexist, carbon monoxide (CO) and water (H ₂ O) contained in the exhaust gas in the rich atmosphere are one on the surface of the noble metal 12a. When a carbon oxide shift reaction occurs, hydrogen (H ₂ ) and carbon dioxide (CO ₂ ) are generated. However, carbon dioxide (CO ₂ ) tends to remain on the surface of the noble metal 12a as it is, and the progress of the carbon monoxide shift reaction is inhibited.
On the other hand, as shown in FIG. 1A, when the oxygen storage / release material coexists, carbon monoxide (CO) and water (H ₂ O) contained in the exhaust gas in a rich atmosphere are present on the surface of the noble metal 12a. When a carbon monoxide shift reaction occurs, hydrogen (H ₂ ) and carbon dioxide (CO ₂ ) are generated. At this time, the defect site α of the oxygen storage / release material 14 stores oxygen (O) of carbon dioxide (CO ₂ ), the carbon monoxide (CO) adsorption poisoning is released, and the carbon monoxide shift on the surface of the noble metal 12a. The reaction will be promoted. In addition, 12b in a figure shows the predetermined oxide which carry | supports a noble metal.

Here, for example, in a gasoline engine, the supply amount of fuel and air is normally controlled by feedback control around A / F 14.6. Therefore, the A / F of the exhaust gas is not constant and is slightly on the lean side or the rich side. Since the emission amount of carbon monoxide (CO) and hydrocarbon (HC) increases on the rich side, hydrogen can be increased by reacting it with water (H ₂ O) in the exhaust gas.
In addition, for example, in a diesel engine, a rich spike may be performed in order to operate a lean NOx trap, and even in that case, emissions of carbon monoxide (CO) and hydrocarbons (HC) in the exhaust gas may be reduced. Since it increases, hydrogen can be increased by reacting it with water (H ₂ O) in the exhaust gas.

In the hydrogen generation catalyst of the present embodiment, the noble metal is preferably rhodium (Rh).
This is because, when rhodium (Rh) is applied among various noble metals, the above-described carbon monoxide shift reaction is more likely to proceed.

Furthermore, in the hydrogen generation catalyst of the present embodiment, the oxides are lanthanum (La), zirconium (Zr), neodymium (Nd), samarium (Sm), europium (Eu), magnesium (Mg), and calcium. It preferably contains at least one additive element selected from the group consisting of (Ca) (hereinafter sometimes referred to as “M”).
This is because when such an oxide is applied, the above-described carbon monoxide shift reaction is more likely to proceed.

The reason why the carbon monoxide shift reaction is likely to proceed is that the specific additive element (M) lowers the binding energy of electrons of noble metals such as rhodium (Rh), and the noble metal behaves more like a simple metal, thereby causing hydrogen This is thought to be due to the mitigation of carbon monoxide (CO) adsorption poisoning in the carbon monoxide shift reaction, which causes a reduction in production performance.

FIG. 2 is an explanatory view showing a mitigation mechanism of carbon monoxide (CO) adsorption poisoning. As shown in FIG. 2 (A), a specific additive element (M) (in the figure, neodymium (Nd) is shown), the noble metal such as rhodium (Rh) becomes a single metal having more electrons than in the case of a metal oxide. Electron repulsion effect occurs, and σ bond from carbon monoxide (CO) becomes difficult.
On the other hand, when a specific additive element (M) is not added, a σ bond is easily formed with carbon monoxide (CO) (see FIG. 2B).

The reason why the bond energy of electrons of the noble metal is lowered by adding a specific additive element (M) is, for example, when there is a bond called Rh-OM, when Rh-O bond and MO bond are present. Is considered to be because the MO bond is stronger.
As a result, the Rh—O bond is easily broken. As a result, the bonding electrons of the Rh—O bond are not in a shared state but are biased toward Rh, and Rh behaves more like a single metal. That is, Rh changes from a metal oxide state to a single metal state in which there are many electrons.

FIG. 3 is a graph showing the results of measuring the state of rhodium (Rh) supported on the oxide of the hydrogen generation catalyst of each example by X-ray photoelectron spectroscopy (XPS).
FIG. 3 shows the electronic state of the 3d orbital of rhodium (Rh), and compared with the oxide of the hydrogen generation catalyst of Comparative Example 1-3, lanthanum (La), zirconium (Zr), neodymium (Nd ), Samarium (Sm), europium (Eu), magnesium (Mg), and an oxide containing at least one additional element selected from the group consisting of calcium (Ca) is supported with a noble metal such as rhodium (Rh). In the oxide of the hydrogen generation catalyst of Example 1-1, it can be seen that rhodium (Rh) is relatively shifted to the low oxidation side and changed to a single metal state.

FIG. 4 is a graph showing the production entropy per oxygen atom of each oxide. The entropy of formation of each oxide before conversion per oxygen atom is quoted from the chemical handbook. FIG. 4 shows that the larger the production entropy value per oxygen atom, the stronger the MO bond.
As shown in FIG. 4, the lanthanum oxide (La ₂ O ₃ ), zirconium oxide (ZrO ₂ ), and aluminum oxide (Al ₂ O ₃ ) having stronger MO bond than neodymium oxide (Nd ₂ It can be seen that they are O ₃ ), samarium oxide (Sm ₂ O ₃ ), europium oxide (Eu ₂ O ₃ ), magnesium oxide (MgO), and calcium oxide (CaO).
Therefore, neodymium (Nd), samarium (Sm), europium (Eu), magnesium (Mg), calcium (Ca) can be applied as the additive element (M). You may apply these individually by 1 type or in combination of 2 or more types.

FIG. 5 is an explanatory diagram showing the interaction between a specific additive element (M) and carbon monoxide (CO).
As shown in FIG. 5, since the specific additive element (M) has an empty orbital in the d orbital, it can be σ-bonded with carbon monoxide (CO), and carbon monoxide (CO on the noble metal surface). ) Can reduce adsorption poisoning.

Further, at least one additive element selected from the group consisting of lanthanum (La), zirconium (Zr), neodymium (Nd), samarium (Sm), europium (Eu), magnesium (Mg), and calcium (Ca) The oxide containing is preferably a complex oxide.
When partly composited, the heat resistance of the zirconium oxide (ZrO ₂ ) can be improved, so that the hydrogen generation performance after durability can be improved.

In the hydrogen generation catalyst of the present embodiment, the oxygen storage / release material preferably contains an oxide containing iron (Fe).
An oxide containing iron (Fe) is an inexpensive oxygen storage / release material, which can improve the efficiency of the carbon monoxide shift reaction without causing a significant cost increase that increases the amount of noble metal used. And the amount of hydrogen generation can be increased.

Further, in the hydrogen generation catalyst of the present embodiment, the oxygen storage / release material may be composed of an oxide containing iron (Fe) and an oxide containing cerium (Ce) disposed in contact with the oxide. preferable.
When an oxide containing iron (Fe) is disposed in contact with an oxide containing cerium (Ce), oxygen in the cerium oxide (CeO ₂ ) is easily released, and an oxidation containing lanthanum (La) and zirconium. Coexisting with a material on which a noble metal is supported can improve the efficiency of the carbon monoxide shift reaction and increase the amount of hydrogen produced. Note that an oxide containing praseodymium (Pr) may be provided in contact with an oxide containing iron (Fe) instead of the oxide containing cerium (Ce).

(Second Embodiment)
Next, the exhaust gas purifying catalyst according to the second embodiment of the present invention will be described in detail.
The exhaust gas purifying catalyst of the present embodiment includes a first catalyst unit composed of a noble metal and an oxide containing lanthanum and zirconium supporting the noble metal, a second catalyst unit composed of an oxygen storage / release material, and a first catalyst. And a holding material that holds the unit and the second catalyst unit in a separated state.

With such a configuration, as described above, the hydrogen generation catalyst having excellent hydrogen generation performance provides excellent purification performance for carbon monoxide (CO), nitrogen oxide (NOx), and the like. In addition, hydrocarbon (HC) also exhibits excellent purification performance.

When the predetermined first catalyst unit and the second catalyst unit are contained in a separated state, deterioration does not proceed due to aggregation due to heat or the like. On the other hand, when the perovskite oxide described later in the first catalyst unit and the second catalyst unit comes into contact with each other, aggregation of the oxide supporting the noble metal in the first catalyst unit is promoted, and as a result, aggregation of the noble metal is promoted. Is done.

Although not particularly limited, from the viewpoint that the first catalyst unit and the second catalyst unit can be held in a more reliably separated state, the pores formed by the holding material are each catalyst. Preferably it is smaller than or the same as the unit particle size.

In the exhaust gas purifying catalyst of the present embodiment, the oxygen storage / release material in the second catalyst unit includes at least one selected from the group consisting of iron (Fe), cobalt (Co), and manganese (Mn). It is preferable that an oxide is included.
For example, when a noble metal such as rhodium (Rh) and a transition metal element such as iron (Fe), cobalt (Co), and manganese (Mn) coexist, the efficiency of the carbon monoxide shift reaction can be improved, and the amount of hydrogen produced Can be increased.

Furthermore, in the exhaust gas purifying catalyst of the present embodiment, the oxygen storage / release material in the second catalyst unit is represented by the general formula (1).
La _x M1 _1-x M2O _3-δ (1)
(In formula (1), La is lanthanum, M1 is at least one selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca), M2 is iron (Fe), cobalt (Co) and manganese) It preferably contains a perovskite oxide represented by the formula (Mn): at least one selected from the group consisting of (Mn), wherein x satisfies 0 <x ≦ 1, and δ satisfies 0 ≦ δ ≦ 1.
The rate-limiting step in the carbon monoxide shift reaction is adsorption of water (H ₂ O) or carbon dioxide (CO ₂ ). For example, when a perovskite oxide having a precious metal such as rhodium (Rh) and a transition metal element such as iron (Fe), cobalt (Co), or manganese (Mn) as a constituent element coexists, these become adsorption sites. The efficiency of the carbon monoxide shift reaction can be improved, and the amount of hydrogen produced can be increased. In addition, the presence of the perovskite type oxide can suppress deterioration due to durability.

In the exhaust gas purifying catalyst of the present embodiment, it is preferable that the oxygen storage / release material contains an oxide containing cerium. Note that an oxide containing praseodymium (Pr) may be used instead of the oxide containing cerium (Ce).
Even under a reducing atmosphere, since oxygen is supplied from the oxygen storage / release material, the collapse of the perovskite structure due to the loss of oxygen in the structure is suppressed. As a result, the catalyst performance can be maintained.

When the first catalyst unit is an oxide containing the specific additive element (M) described above, carbon monoxide (CO) adsorption poisoning in a carbon monoxide shift reaction that causes a reduction in hydrogen generation performance. Is alleviated and has excellent hydrogen generation performance.

In addition, when the second catalyst unit is arranged in contact with the oxygen storage / release material that releases oxygen in a rich atmosphere and the perovskite oxide, the oxygen storage / release material can be used even in a reducing atmosphere. Since oxygen is supplied, collapse of the perovskite structure due to the loss of oxygen in the structure is suppressed. As a result, the catalyst performance can be maintained. When oxides containing a transition metal element that is not a perovskite type are applied, these oxides may react with the holding material, resulting in a reduction in catalyst performance.

(Third embodiment)
Next, an exhaust gas purifying monolith catalyst according to a third embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 6 is an explanatory view showing a monolith catalyst for exhaust gas purification according to the third embodiment. FIG. 6A is a perspective view showing the monolith catalyst for exhaust gas purification of this embodiment. FIG. 6 (B) is a front view schematically showing a portion surrounded by an encircling line B of the exhaust gas purifying monolith catalyst shown in FIG. 6 (A). FIG. 6C is an enlarged view schematically showing a portion surrounded by an encircling line C of the exhaust gas purifying monolith catalyst shown in FIG. 6B. FIG. 6 (D) is an enlarged view schematically showing a part surrounded by an encircling line D of the exhaust gas purifying monolith catalyst shown in FIG. 6 (C). As shown in FIGS. 6A to 6C, the exhaust gas purifying monolith catalyst 1 of the present embodiment has a catalyst layer 10 containing the exhaust gas purifying catalyst of the second embodiment described above. It is formed in the exhaust gas flow path 30a. Moreover, in this embodiment, the undercoat layer 20 mentioned later is formed. As shown in FIG. 6D, the exhaust gas-purifying catalyst 11 in the present embodiment includes a first catalyst unit 12, a second catalyst unit 14, a first catalyst unit 12, and a second catalyst. A holding member 16 that holds the unit 14 in a separated state is contained.
The first catalyst unit 12 is composed of the above-described noble metal 12a and the oxide 12b containing lanthanum (La) and zirconium (Zr) supporting the noble metal 12a.
The second catalyst unit 14 is made of an oxygen storage / release material, and in the present embodiment, the cerium-containing oxide 14a and the predetermined perovskite oxidation described above disposed in contact with the cerium-containing oxide 14a. It consists of thing 14b. The first catalyst unit and the second catalyst unit cooperate to function as a hydrogen generation catalyst.
Furthermore, as the monolithic carrier 30, a honeycomb carrier made of a heat-resistant material such as ceramics such as cordierite or a metal such as ferritic stainless steel can be applied.

With such a configuration, the contact between the exhaust gas purifying catalyst and the exhaust gas is improved, and the catalyst performance can be further improved.

As shown in FIG. 6C, the exhaust gas purifying monolithic catalyst preferably has an undercoat layer containing a heat-resistant inorganic oxide in the lowermost layer of the catalyst layer.
As described above, by coating the monolith carrier with the exhaust gas purification catalyst to form a catalyst layer, the contact between the exhaust gas purification catalyst and the exhaust gas is improved, and the catalyst performance can be further improved. However, when the exhaust gas purification catalyst is coated on the monolithic carrier, the catalyst gathers at the corners of the honeycomb carrier, and the coating layer is partially thickened. When the coat layer is thick, the exhaust gas is difficult to diffuse, and the catalyst disposed at the corner is not used for purification of the exhaust gas. In order to prevent this, by providing an undercoat layer and eliminating the corners of the honeycomb carrier, it is possible to reduce the exhaust gas purifying catalyst disposed in the portion where the contact between the exhaust gas purifying catalyst and the exhaust gas is low.

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

Example 1-1
3 mass% lanthanum oxide (La ₂ O ₃ ) -5 mass% neodymium oxide (Nd ₂ O ₃ ) -zirconium oxide (ZrO ₂ ) (hereinafter referred to as “lanthanum oxide (La ₂ O ₃ ) -neodymium oxide ( Nd ₂ O ₃ ) -zirconium oxide (ZrO ₂ ) ”is sometimes simply referred to as“ ZrLaNd oxide ”), and a hexarhodium salt was impregnated by an incipient wetness method. Subsequently, it dried at 150 degreeC for 12 hours. Thereafter, it was calcined at 400 ° C. for 1 hour to obtain a first catalyst unit (powder). In addition, the rhodium (Rh) carrying | support density | concentration in the 1st catalyst unit of this example is 0.092 mass%.
Next, 20 mass% cerium oxide (CeO ₂ ) —10 mass% neodymium oxide (Nd ₂ O ₃ ) —zirconium oxide (ZrO ₂ ) (hereinafter “cerium oxide (CeO ₂ ) —neodymium oxide (Nd ₂ )” O ₃ ) -zirconium oxide (ZrO ₂ ) ”may be simply referred to as“ ZrCeNd oxide ”.) An aqueous solution in which a lanthanum (La) salt, a strontium (Sr) salt, and an iron (Fe) salt are dissolved Was impregnated. Subsequently, it dried at 150 degreeC for 12 hours. Thereafter, it was calcined at 400 ° C. for 2 hours and further calcined at 700 ° C. for 5 hours to obtain a second catalyst unit (powder).
Thereafter, the first catalyst unit and the second catalyst unit are weighed so that the weight ratio of the first catalyst unit: the second catalyst unit = 5: 2 and mixed in a mortar for 5 minutes, The hydrogen generation catalyst of this example was obtained.

(Comparative Example 1-1)
The first catalyst unit obtained in Example 1-1 was used as the hydrogen generation catalyst of this example.

(Comparative Example 1-2)
The second catalyst unit obtained in Example 1-1 was used as the hydrogen generation catalyst of this example.

(Comparative Example 1-3)
3 mass% lanthanum oxide (La ₂ O ₃ ) -zirconium oxide (ZrO ₂ ) (hereinafter “lanthanum oxide (La ₂ O ₃ ) -zirconium oxide (ZrO ₂ )” is simply referred to as “ZrLa oxide”. ) Was impregnated with an incipient wetness method. Subsequently, it dried at 150 degreeC for 12 hours. Thereafter, it was calcined at 400 ° C. for 1 hour to obtain a first catalyst unit (powder). In addition, the rhodium (Rh) carrying | support density | concentration in the 1st catalyst unit of this example is 0.092 mass%.
The first catalyst unit obtained in this example was used as the hydrogen generation catalyst of this example.

[Performance evaluation]
(Hydrogen production performance test)
Using the hydrogen generation catalyst (powder) in each of the above examples, a carbon monoxide shift reaction test was performed under the following conditions. The obtained results are shown in Table 1.

(Test conditions)
-Sample amount: 0.2g
Measurement conditions: According to the measurement program shown in FIG.
-Temperature reduction measurement: Gas components were detected with a quadrupole mass spectrometer.
Detection fragment: m / z = 2, 18, 28, 44
・ Measurement temperature: 400 ℃
Measurement atmosphere: 2.5% by volume CO, H ₂ O / He (introducing bubbling at room temperature)
・ Flow rate: 100ml / min

From Table 1, Example 1-1, which belongs to the scope of the present invention, has a higher hydrogen production rate than the Comparative Examples 1-1 to 1-3 outside the present invention, and the carbon monoxide shift reaction proceeds efficiently. I understand that. Further, in Example 1-1, more hydrogen was produced than the sum of Comparative Example 1-1 and Comparative Example 1-2.

Example 2-1
(1) ZrLaNd oxide was impregnated with a predetermined amount of rhodium (Rh). Next, it was dried and fired to obtain an Rh / ZrLaNd oxide powder. Next, pure water was added to the powder so that the solid content was 40% by mass, and the powder was pulverized to obtain a first catalyst unit-containing slurry.
(2) A ZrCeNd oxide was impregnated with a predetermined amount of LaSrFeO ₃ so that iron (Fe) was 5 mass%. Next, it was dried and fired to obtain a LaSrFeO ₃ / ZrCeNd oxide powder. Next, this powder was charged with pure water so that the solid content was 40% by mass and pulverized to obtain a second catalyst unit-containing slurry.
(3) A predetermined amount of the slurry obtained in the above (1) and (2) and boehmite were mixed to obtain a mixed slurry. Next, the mixed slurry was dried and calcined at 550 ° C. for 3 hours to obtain a powder containing the first catalyst unit and the second catalyst unit. In addition, the rhodium (Rh) carrying | support density | concentration in the 1st catalyst unit of this example is 0.092 mass%.

(Example 2-2)
(1) ZrLaNd oxide was impregnated with a predetermined amount of rhodium (Rh). Next, it was dried and fired to obtain an Rh / ZrLaNd oxide powder. Next, pure water was added to the powder so that the solid content was 40% by mass, and the powder was pulverized to obtain a first catalyst unit-containing slurry.
(2) A ZrCeNd oxide was impregnated with a predetermined amount of LaSrFeO ₃ so that iron (Fe) was 5 mass%. Next, it was dried and fired to obtain a LaSrFeO ₃ / ZrCeNd oxide powder. Next, this powder was charged with pure water so that the solid content was 40% by mass and pulverized to obtain a second catalyst unit-containing slurry.
(3) A predetermined amount of the slurry obtained in the above (1) and (2) and boehmite were mixed to obtain a mixed slurry. Next, the mixed slurry was dried and fired at 550 ° C. for 3 hours to obtain a surface layer powder.
(4) The powder, binder, nitric acid, and pure water obtained in the above (3) were put into a magnetic pot, and shaken and pulverized with alumina balls to obtain a surface layer slurry.
(5) Aluminum oxide (Al ₂ O ₃ ), binder, nitric acid, and pure water were put into a magnetic pot and shaken and ground with alumina balls to obtain an inner layer slurry.
(6) The inner layer slurry obtained in the above (5) was put into a ceramic honeycomb carrier, and excess inner layer slurry was removed by an air flow. Subsequently, it dried at 120 degreeC. The coating amount at this time is 113 g / L.
(7) The surface layer slurry obtained in the above (4) was put into the carrier obtained in the above (6), and the excess surface layer slurry was removed by an air flow. Subsequently, it dried at 120 degreeC. Thereafter, it was calcined at 400 ° C. under air flow to obtain the monolith catalyst for exhaust gas purification of this example. The coating amount at this time was 124 g / L. Moreover, the rhodium (Rh) amount in the monolith catalyst for exhaust gas purification was 0.03 g / L.

(Example 2-3)
In Example 2-2, except that iron (Fe), which is an M2 element, is changed to cobalt (Co), which is an M2 element, the same operation as in Example 2-2 is repeated, and this example is for exhaust gas purification. A monolith catalyst was obtained.

(Example 2-4)
In Example 2-2, the same operation as in Example 2-2 was repeated except that iron (Fe) as the M2 element was changed to manganese (Mn) as the M2 element. A monolith catalyst was obtained.

(Comparative Example 2-1)
(1) ZrLaNd oxide was impregnated with a predetermined amount of rhodium (Rh). Next, it was dried and fired to obtain an Rh / ZrLaNd oxide powder. Next, pure water was added to the powder so that the solid content was 40% by mass, and the powder was pulverized to obtain a first catalyst unit-containing slurry.
(2) In addition, ZrCeNd oxide powder was charged with pure water so that the solid content was 40% by mass and pulverized to obtain a second catalyst unit-containing slurry.
(3) A predetermined amount of the slurry obtained in the above (1) and (2) and boehmite were mixed to obtain a mixed slurry. Next, the mixed slurry was dried and calcined at 550 ° C. for 3 hours to obtain a powder containing the first catalyst unit and the second catalyst unit. In addition, the rhodium (Rh) carrying | support density | concentration in the 1st catalyst unit of this example is 0.092 mass%.

(Comparative Example 2-2)
(1) ZrLaNd oxide was impregnated with a predetermined amount of rhodium (Rh). Next, it was dried and fired to obtain an Rh / ZrLaNd oxide powder. Next, pure water was added to the powder so that the solid content was 40% by mass, and the powder was pulverized to obtain a first catalyst unit-containing slurry.
(2) In addition, ZrCeNd oxide powder was charged with pure water so that the solid content was 40% by mass and pulverized to obtain a second catalyst unit-containing slurry.
(3) A predetermined amount of the slurry and boehmite obtained in (1) and (2) above were mixed to obtain a mixed slurry. Next, the mixed slurry was dried and fired at 550 ° C. for 3 hours to obtain a surface layer powder.
Binder, nitric acid, and pure water were put into a magnetic pot and shaken and pulverized with alumina balls to obtain a surface layer slurry. Using this slurry, the average particle size of the exhaust gas-purifying catalyst powder was measured. The obtained results are shown in Table 2.
(4) The powder, binder, nitric acid, and pure water obtained in the above (3) were put into a magnetic pot, and shaken and pulverized with alumina balls to obtain a surface layer slurry.
(5) Aluminum oxide (Al ₂ O ₃ ), binder, nitric acid, and pure water were put into a magnetic pot and shaken and ground with alumina balls to obtain an inner layer slurry.
(6) The inner layer slurry obtained in the above (5) was put into a ceramic honeycomb carrier, and excess inner layer slurry was removed by an air flow. Subsequently, it dried at 120 degreeC. The coating amount at this time is 113 g / L.
(7) The surface layer slurry obtained in the above (4) was put into the carrier obtained in the above (6), and the excess surface layer slurry was removed by an air flow. Subsequently, it dried at 120 degreeC. Thereafter, it was calcined at 400 ° C. under air flow to obtain the monolith catalyst for exhaust gas purification of this example. The coating amount at this time was 124 g / L. Moreover, the rhodium (Rh) amount in the monolith catalyst for exhaust gas purification was 0.03 g / L.

(Comparative Example 2-3)
(1) ZrLaNd oxide was impregnated with a predetermined amount of rhodium (Rh). Next, it was dried and fired to obtain an Rh / ZrLaNd oxide powder. Next, pure water was added to the powder so that the solid content was 40% by mass, and the powder was pulverized to obtain a first catalyst unit-containing slurry.
(2) A ZrCeNd oxide was impregnated with a predetermined amount of LaSrFeO ₃ so that iron (Fe) was 5 mass%. Next, it was dried and fired to obtain a LaSrFeO ₃ / ZrCeNd oxide powder. Next, this powder was charged with pure water so that the solid content was 40% by mass and pulverized to obtain a second catalyst unit-containing slurry.
(3) A predetermined amount of the slurry obtained in the above (1) and (2) and boehmite were mixed to obtain a mixed slurry. Next, the mixed slurry was dried and fired at 550 ° C. for 3 hours to obtain a surface layer powder.
(4) The powder, binder, nitric acid, and pure water obtained in the above (3) were put into a magnetic pot, and shaken and pulverized with alumina balls to obtain a surface layer slurry.
(5) Aluminum oxide (Al ₂ O ₃ ), binder, nitric acid, and pure water were put into a magnetic pot and shaken and ground with alumina balls to obtain an inner layer slurry.
(6) The inner layer slurry obtained in the above (5) was put into a ceramic honeycomb carrier, and excess inner layer slurry was removed by an air flow. Subsequently, it dried at 120 degreeC. The coating amount at this time is 113 g / L.
(7) The surface layer slurry obtained in the above (4) was put into the carrier obtained in the above (6), and the excess surface layer slurry was removed by an air flow. Subsequently, it dried at 120 degreeC. Thereafter, it was calcined at 400 ° C. under air flow to obtain the monolith catalyst for exhaust gas purification of this example. The coating amount at this time was 124 g / L. Moreover, the rhodium (Rh) amount in the monolith catalyst for exhaust gas purification was 0.03 g / L.
Table 2 shows a part of the specifications of each example.

[Performance evaluation]
(Hydrogen production performance test)
Using the hydrogen generation catalyst (powder) of Example 2-1 and Comparative Example 2-1, a carbon monoxide shift reaction test was performed under the following conditions. The obtained results are shown in Table 2.

(NOx emission measurement)
FIG. 8 is an explanatory view showing the catalyst arrangement in the NOx emission amount measurement. As shown in FIG. 8, the three-way catalyst 2 is arranged directly below (manifold position) of an engine 100 of a vehicle manufactured by Nissan Motor Co., Ltd. having a displacement of 1.5 L, and is endured under the following conditions downstream thereof. The exhaust gas purification monolithic catalyst 1 of Example 2-4, Comparative Example 2-2, and Comparative Example 2-3 is disposed and travels in NEDC mode (cold start). NOx emission in the monolith catalyst was measured. The obtained results are shown in Table 2.

<Durability conditions>
A catalyst was placed behind the Nissan Motor Co., Ltd. V-6 cylinder 3.5L engine, the catalyst inlet temperature was adjusted to 840 ° C., and 250 hours durability treatment was performed in an exhaust gas atmosphere. The fuel used was unleaded gasoline.

Table 2 shows that Example 2-1 belonging to the scope of the present invention produces more hydrogen than Comparative Example 2-1 outside the present invention, and the carbon monoxide shift reaction proceeds efficiently.
Further, from Table 2, Examples 2-2 to 2-4 belonging to the scope of the present invention have less NOx emissions than Comparative Examples 2-2 and 2-3 outside the present invention. I understand.

As mentioned above, although this invention was demonstrated by some embodiment and an Example, this invention is not limited to these, A various deformation | transformation is possible within the range of the summary of this invention.

For example, the configurations described in the hydrogen generation catalyst, the exhaust gas purification catalyst, and the exhaust gas purification monolith catalyst of each embodiment and each example described above are not limited to each embodiment or each example. The configurations of the embodiments and examples can be combined with those other than the embodiments and examples described above, or the details of the configurations can be changed.

DESCRIPTION OF SYMBOLS 1 Monolith catalyst for exhaust gas purification 2 Three-way catalyst 10 Catalyst layer 11 Catalyst for exhaust gas purification 12 First catalyst unit 12a Precious metal 12b Oxide 14 Second catalyst unit (oxygen storage / release material)
14a Cerium-containing oxide 14b Perovskite oxide 16 Holding material 20 Undercoat layer 30 Monolith support 30a Exhaust gas flow channel 100 Engine α Defect site

Claims

With precious metals,
An oxide containing lanthanum and zirconium supporting the noble metal;
A hydrogen generation catalyst comprising an oxygen storage / release material.
2. The hydrogen generation catalyst according to claim 1, wherein the noble metal is rhodium.
3. The hydrogen generation according to claim 1, wherein the oxide contains lanthanum, zirconium, and at least one additive element selected from the group consisting of neodymium, samarium, europium, magnesium, and calcium. Catalyst.
The hydrogen generation catalyst according to any one of claims 1 to 3, wherein the oxygen storage / release material contains an oxide containing iron.
5. The oxygen storage / release material comprises an oxide containing iron and an oxide containing cerium disposed in contact with the oxide. Catalyst for hydrogen production.
A first catalyst unit comprising a noble metal and an oxide containing lanthanum and zirconium supporting the noble metal;
A second catalyst unit comprising an oxygen storage / release material;
An exhaust gas purifying catalyst comprising: a holding material that holds the first catalyst unit and the second catalyst unit in a separated state.
The exhaust gas purifying catalyst according to claim 6, wherein the oxygen storage / release material in the second catalyst unit contains an oxide containing at least one selected from the group consisting of iron, cobalt and manganese.
The oxygen storage / release material in the second catalyst unit is represented by the general formula (1).
La x M1 1-x M2O 3-δ (1)
(In formula (1), La is lanthanum, M1 is at least one selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca), M2 is iron (Fe), cobalt (Co) and manganese) And at least one selected from the group consisting of (Mn), wherein x satisfies 0 <x ≦ 1 and δ satisfies 0 ≦ δ ≦ 1). The exhaust gas-purifying catalyst according to claim 6 or 7.
The exhaust gas purifying catalyst according to any one of claims 6 to 8, wherein the oxygen storage / release material contains an oxide containing cerium.
An exhaust gas purifying monolith catalyst, characterized in that the catalyst layer containing the exhaust gas purifying catalyst according to any one of claims 6 to 9 is formed in an exhaust passage of a monolith carrier.