JP5942550B2 - Particulate combustion catalyst and method for producing the same - Google Patents

Description

The present invention relates to a particulate matter combustion catalyst for burning particulate matter contained in engine exhaust gas and a method for producing the same .

  In a diesel engine vehicle, a diesel particulate filter (DPF: Diesel Particulate Filter) may be provided with a catalyst for burning particulate matter (PM) contained in exhaust gas. Also, in gasoline engine vehicles, especially in direct injection type gasoline engines, fuel near the spark plug tends to be excessively concentrated during stratified lean combustion, and smoke is likely to be generated. Removal is desired.

  On the other hand, Patent Document 1 describes using a double oxide of Zr, at least one rare earth metal excluding Ce, and a noble metal as a catalyst material for burning the particulate matter. That is, it is known that the Zr-based oxide has oxygen ion conductivity that causes oxygen ions to move from a portion having a high oxygen concentration to a portion having a low oxygen concentration to release oxygen from the particle surface. Patent Document 1 discloses that the Zr-based oxide is a double oxide of Zr, at least one rare earth metal excluding Ce, and a noble metal, thereby improving the oxygen ion conductivity, thereby forming a particulate form. Disclosing improving the flammability of a substance is disclosed.

  Patent Document 2 discloses a Zr-based complex oxide containing Zr as a main component metal element and a rare earth metal excluding Ce and Y as a particulate material combustion catalyst material supported on a DPF, and Ce as a main component. It is described that a Ce-based double oxide containing a rare earth metal or an alkaline earth metal other than Ce as a component metal element and supporting a noble metal on the double oxide is described.

JP 2007-69076 A JP 2007-54713 A

  The Zr-based double oxides described in Patent Document 1 and Patent Document 2 also show excellent performance as a catalyst material for burning particulate matter, but the present invention further improves the combustibility of the particulate matter. It is an object to provide a catalyst.

  In order to solve the above problems, the present invention employs a configuration in which a Zr-based double oxide is further doped with an alkaline earth metal in addition to Nd as a rare earth metal.

That is, in one embodiment of the particulate matter combustion catalyst presented here, a catalyst layer is provided on a support base material, and Zr and Nd for burning particulate matter contained in engine exhaust gas to the catalyst layer. And a catalyst material containing Ca and a noble metal is provided. In the catalyst material, Zr, Nd, and Ca form a double oxide, and the main component metal element of the double oxide is Zr. The
The primary particles of the double oxide and the primary particles of the noble metal are mixed together to form secondary particles, and at least part of the primary particles of the noble metal are exposed on the surface of the secondary particles. and said that you are.

In the double oxide according to this catalyst material, tetravalent Zr which is a main component metal element is doped with divalent alkaline earth metal Ca in addition to trivalent rare earth metal Nd. (Atomic vacancies) increase and oxygen ion conductivity increases. For this reason, oxygen is actively released from the surface of the double oxide particles, and the burning rate of the particulate matter is increased. That is, it is advantageous for rapid combustion removal of the particulate matter by the noble metal. Moreover, since the alkaline earth metal Ca forms a basic site in the double oxide, the power to attract NO contained in the exhaust gas is increased. As a result, oxidation of NO to NO ₂ by the noble metal is promoted, and particulate matter can be burned by the NO ₂ .

  Here, if Ca is supported on the surface of the Zr-based double oxide, the Ca becomes a steric hindrance (the noble metal is covered), and the active site of the catalyst is reduced. On the other hand, in the present invention, since Ca is doped into the Zr-based double oxide, there is no problem of the steric hindrance.

  Further, Ca is advantageous in that the oxygen vacancy is formed because the ionic radius is close to Zr, and Ca is preferable in that the ionic radius is not too large and the steric hindrance to the movement of oxygen vacancies is difficult. . The ionic radius is 0.84Ｚ for Zr and 1.12Å for Ca (Revised Effective Ionic Radii and Systematic Studies of Interatomie Distances in Halides and Chaleogenides Acta Cryst. (1976). A32, 751-767 BY R. D. SHANNON).

  The engine may be a diesel engine or a gasoline engine. Therefore, the carrier substrate is not limited to a DPF, and may be a honeycomb carrier. Moreover, as said noble metal, it is preferable to employ | adopt 1 type, or 2 or more types from Pt, Pd, Rh, etc.

Also, necessarily involves the transfer of electrons in the combustion of the particulate matter due to movement of the oxygen ions in the upper Kifuku oxide. In the case where the primary particles of the double oxide and the primary particles of the noble metal are aggregated, the noble metal contributes to the movement of the electrons between the primary particles of the double oxide, thereby promoting the movement of oxygen or oxygen ions. To do. As a result, the release of oxygen from the secondary particles (catalyst material) becomes active, which is advantageous for the combustion of particulate matter. In addition, since the primary particles of the noble metal are exposed on the surface of the secondary particles (catalyst material), the oxygen exchange reaction that takes in oxygen in the exhaust gas and releases the internal oxygen as active oxygen is promoted by the noble metal, This is advantageous for the combustion removal of particulate matter.

The catalyst material is obtained by adding a basic solution to an acidic solution containing Zr ions, Nd ions, and Ca ions, mixing the noble metal solution with the obtained coprecipitate, and calcining the mixture. Can do. That is, primary particles of the double oxide and primary particles of the noble metal are mixed together to form secondary particles, and at least a part of the primary particles of the noble metal is exposed on the surface of the secondary particles. Catalyst material is obtained. And the said particulate-material combustion catalyst material can be obtained by carry | supporting this catalyst material on a support base material. As the Zr source, Nd source, and Ca source, for example, nitrates and acetates can be employed, and as the basic solution, for example, ammonia water or sodium hydroxide aqueous solution can be employed .

Another aspect of the particulate matter combustion catalyst that presented here includes Zr and Nd for the catalyst layer is provided on a carrier substrate, to burn the particulate matter contained in exhaust gas of the engine to the catalyst layer and the catalyst material is provided containing a Sr and precious metals, in該触Baizai, and the Zr, Nd, Sr form a mixed oxide, Ri main component metal element Zr der of the double oxide ,
The primary particles of the double oxide and the primary particles of the noble metal are mixed together to form secondary particles, and at least part of the primary particles of the noble metal are exposed on the surface of the secondary particles. and said that you are.

That is, this example is a case where the alkaline earth metal is Sr. Also in this case, as in the case of the previous Ca, the above-mentioned double oxide has more oxygen vacancies (atomic vacancies) due to Sr doping, and oxygen ion conductivity increases, so that the combustion of particulate matter Increases speed. In addition, since Sr forms a basic site in the double oxide, the power of attracting NO contained in the exhaust gas is strengthened, and the oxidation of NO to NO ₂ by the noble metal is promoted, and the NO ₂ is particulate. The combustion of the substance is promoted.

  The engine may be a diesel engine or a gasoline engine. Therefore, the carrier substrate is not limited to a DPF, and may be a honeycomb carrier. As the noble metal, it is preferable to employ one or more of Pt, Pd, Rh and the like.

The catalyst material, since ing aggregate to form a primary particle and the primary particles and are mixed each other by secondary particles of the noble metal of the mixed oxide, as with Ca case, the noble metal mixed oxide By contributing to the movement of electrons between the primary particles of the object, the movement of oxygen or oxygen ions is promoted, which is advantageous for the combustion of particulate matter. Further, since the primary particles of the noble metal are exposed on the surfaces of the secondary particles (catalyst material), the oxygen exchange reaction is promoted, which is advantageous for the combustion removal of the particulate matter.

The secondary particle catalyst material is obtained by adding a basic solution to an acidic solution containing Zr ions, Nd ions, and Sr ions, mixing the resulting noble metal solution with the coprecipitate, and firing the mixture. Can be obtained by: And the said particulate-material combustion catalyst material can be obtained by carry | supporting this catalyst material on a support base material. As the Zr source, Nd source, and Sr source, for example, nitrates and acetates can be employed, and as the basic solution, for example, ammonia water or sodium hydroxide aqueous solution can be employed .

Yet another aspect of the particulate matter combustion catalyst that presented here, the catalyst layer is provided on a carrier substrate, Zr and Nd for burning particulate matter contained in exhaust gas of the engine to the catalyst layer In the catalyst material, Zr, Nd, and Ba form a double oxide, and the main component metal element of the double oxide is Zr. The
The primary particles of the double oxide and the primary particles of the noble metal are mixed together to form secondary particles, and at least part of the primary particles of the noble metal are exposed on the surface of the secondary particles. and said that you are.

That is, this example is a case where the alkaline earth metal is Ba. Also in this case, as in the case of the previous Ca, the above-mentioned double oxide has more oxygen vacancies (atomic vacancies) due to Ba doping, and oxygen ion conductivity becomes higher, so that the combustion of particulate matter Increases speed. Further, since the Ba forms a basic site in the mixed oxide, the force to attract the NO contained in the exhaust gas becomes strong, the oxidation of NO to NO ₂ by the noble metal is promoted, particulate by the NO ₂ The combustion of the substance is promoted.

  The engine may be a diesel engine or a gasoline engine. Therefore, the carrier substrate is not limited to a DPF, and may be a honeycomb carrier. As the noble metal, it is preferable to employ one or more of Pt, Pd, Rh and the like.

Further, the catalyst material, since ing aggregate to form a primary particle and the primary particles and are mixed each other by secondary particles of the noble metal of the mixed oxide, as with Ca case, the noble metal By contributing to the movement of electrons between the primary particles of the double oxide, the movement of oxygen or oxygen ions is promoted, which is advantageous for the combustion of particulate matter. Further, since the primary particles of the noble metal are exposed on the surfaces of the secondary particles (catalyst material), the oxygen exchange reaction is promoted, which is advantageous for the combustion removal of the particulate matter.

The secondary particle catalyst material is obtained by adding a basic solution to an acidic solution containing Zr ions, Nd ions, and Ba ions, mixing the resulting noble metal solution with the resulting coprecipitate, and firing the mixture. Can be obtained by: And the said particulate-material combustion catalyst material can be obtained by carry | supporting this catalyst material on a support base material. As the Zr source, Nd source, and Ba source, for example, nitrates and acetates can be used, and as the basic solution, for example, ammonia water or sodium hydroxide aqueous solution can be used.

Yet another embodiment of the particulate matter combustion catalyst presented here is that a catalyst layer is provided on the support base, and Zr and Nd for burning the particulate matter contained in the exhaust gas of the engine to the catalyst layer. and the catalyst material is provided which contains Mg and precious metals, in該触Baizai, and the Zr, Nd, Mg forms a mixed oxide, Ri main component metal element Zr der of the double oxide ,
The primary particles of the double oxide and the primary particles of the noble metal are mixed together to form secondary particles, and at least part of the primary particles of the noble metal are exposed on the surface of the secondary particles. and said that you are.

That is, this example is a case where the alkaline earth metal is Mg. Also in this case, as in the case of the previous Ca, the above-mentioned double oxide has more oxygen vacancies (atomic vacancies) due to Mg doping, and oxygen ion conductivity becomes higher, so that the combustion of particulate matter Increases speed. Further, since Mg forms a basic site in the double oxide, the power of attracting NO contained in the exhaust gas is increased, and the oxidation of NO to NO ₂ by the noble metal is promoted, and the NO ₂ is particulate. The combustion of the substance is promoted.

  Further, the Mg has an ionic radius close to Zr, which is advantageous in forming the oxygen vacancies, and the ionic radius is not so large that the steric hindrance to the movement of oxygen vacancies is difficult. preferable. The ionic radius of Mg is 0.89 mm (Revised Effective Ionic Radii and Systematic Studies of Interatomie Distances in Halides and Chaleogenides Acta Cryst. (1976). A32, 751-767 BY R. D. SHANNON).

  The engine may be a diesel engine or a gasoline engine. Therefore, the carrier substrate is not limited to a DPF, and may be a honeycomb carrier. As the noble metal, it is preferable to employ one or more of Pt, Pd, Rh and the like.

Moreover, the catalyst material, since ing aggregate to form a primary particle and the primary particles and are mixed each other by secondary particles of the noble metal of the mixed oxide, as with Ca case, the noble metal By contributing to the movement of electrons between the primary particles of the double oxide, the movement of oxygen or oxygen ions is promoted, which is advantageous for the combustion of particulate matter. Further, since the primary particles of the noble metal are exposed on the surfaces of the secondary particles (catalyst material), the oxygen exchange reaction is promoted, which is advantageous for the combustion removal of the particulate matter.

The secondary particle catalyst material is obtained by adding a basic solution to an acidic solution containing Zr ions, Nd ions, and Mg ions, mixing the resulting noble metal solution with the resulting coprecipitate, and firing the mixture. Can be obtained by: And the said particulate-material combustion catalyst material can be obtained by carry | supporting this catalyst material on a support base material. As the Zr source, Nd source, and Mg source, for example, nitrate or acetate can be used, and as the basic solution, for example, ammonia water or sodium hydroxide aqueous solution can be used.

According to the present invention, the catalyst material constituting the particulate matter combustion catalyst contains Zr, Nd, a double oxide of Ca, Sr, Ba or Mg, and a noble metal, and the double oxide main component metal element Zr der of is, become aggregated so as to form primary particles and primary particles and are mixed each other by secondary particles of the noble metal of the mixed oxide, at least one primary particles of the noble metal since part is it is exposed to the secondary particle surface, which is advantageous in rapid burning and removing particulate matter.

It is a figure which shows the state which has arrange | positioned the particulate filter in the exhaust-gas channel | path of an engine. It is a front view which shows a particulate filter typically. It is a longitudinal section showing a particulate filter typically. It is an expanded sectional view showing typically the wall which separates the exhaust-gas inflow path and exhaust-gas outflow path of a particulate filter. The catalyst material according to the embodiment is a view schematically showing. It is a figure which shows typically the catalyst material which concerns on a reference form. It is a graph which shows the carbon burning rate of the Example of the case which employ | adopted Ca as an alkaline-earth metal , a reference example, and a comparative example. It is a graph which shows the amount of lattice oxygen discharge | release of the Example of the same case , a reference example, and a comparative example. It is a graph which shows the carbon burning rate of the Example of the case which employ | adopted Sr as an alkaline-earth metal , a reference example, and a comparative example. It is a graph which shows the amount of lattice oxygen discharge | release of the Example of the same case , a reference example, and a comparative example. It is a graph which shows the carbon burning rate of the Example of the case which employ | adopted Ba as an alkaline-earth metal , a reference example, and a comparative example. It is a graph which shows the amount of lattice oxygen discharge | release of the Example of the same case , a reference example, and a comparative example. It is a graph which shows the carbon burning rate of the Example of the case which employ | adopted Mg as an alkaline-earth metal , a reference example, and a comparative example. It is a graph which shows the amount of lattice oxygen discharge | release of the Example of the same case , a reference example, and a comparative example. It is a figure which shows the XRD profile of a catalyst material.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or its use.

  The particulate matter combustion catalyst according to the present embodiment is obtained by providing a catalyst material on a particulate filter that collects particulate matter in exhaust gas of a diesel engine. Of course, the present invention may be configured such that the honeycomb carrier is provided with a catalyst material so as to be used for combustion removal of particulate matter contained in the exhaust gas of the direct injection type gasoline engine.

<Particulate filter structure>
FIG. 1 shows a particulate filter (hereinafter simply referred to as “filter”) 1 disposed in an exhaust gas passage 11 of a diesel engine. In the exhaust gas passage 11 on the upstream side of the exhaust gas flow from the filter 1, an oxidation catalyst (not shown) in which a catalytic metal typified by Pt, Pd or the like is supported on a support material such as activated alumina can be disposed. . When such an oxidation catalyst is arranged on the upstream side of the filter 1, the oxidation catalyst oxidizes HC and CO in the exhaust gas, and the temperature of the exhaust gas flowing into the filter 1 is increased by the oxidation combustion heat so that the filter 1 By heating, the particulates can be burned off. Further, NO is oxidized to NO ₂ by the oxidation catalyst, and the NO ₂ is supplied to the filter 1 as an oxidant for burning the particulate matter.

  As schematically shown in FIGS. 2 and 3, the filter 1 has a honeycomb structure and includes a number of exhaust gas passages 2 and 3 extending in parallel with each other. That is, the filter 1 is provided with an exhaust gas inflow path 2 whose downstream end is closed by the plug 4 and an exhaust gas outflow path 3 whose upstream end is closed by the plug 4, and the exhaust gas inflow path 2 and the exhaust gas are alternately provided. The gas outflow path 3 is separated by a thin partition wall 5. In FIG. 2, hatched portions indicate the plugs 4 at the upstream end of the exhaust gas outflow passage 3.

In the filter 1, the filter body including the partition wall 5 is formed of an inorganic porous material such as cordierite, SiC, Si ₃ N ₄ , sialon, and the exhaust gas flowing into the exhaust gas inflow passage 2 is shown in FIG. As shown by the arrow in FIG. 5, the gas flows out through the surrounding partition wall 5 into the adjacent exhaust gas outflow passage 3. That is, as shown in FIG. 4, the partition wall 5 has minute pores (exhaust gas passages) 6 that connect the exhaust gas inflow passage 2 and the exhaust gas outflow passage 3, and the exhaust gas passes through the pores 6. . Particulate matter is trapped and deposited mainly in the exhaust gas inflow passage 2 and the walls of the pores 6.

  A catalyst layer 7 is formed on the wall surface forming the exhaust gas passages (exhaust gas inflow passage 2, exhaust gas outflow passage 3 and pores 6) of the filter body as the carrier substrate. It is not always necessary to form a catalyst layer on the wall surface on the exhaust gas outflow path 3 side.

  The catalyst layer 7 contains a catalyst material for burning off particulate matter deposited on the filter 1. The catalyst material contains a double oxide of Zr, Nd, Ca, Sr, Mg or Ba and a noble metal, and the main component metal element of the double oxide is Zr.

As schematically shown in FIG. 5, the catalyst material is aggregated so that the primary particles 11 of the double oxide and the primary particles 12 of the noble metal are mixed to form secondary particles 13. At least a part of the primary particles 12 of the noble metal is exposed on the surface of the secondary particles 13.

In the catalyst material according to the reference embodiment, as schematically shown in FIG. 6, the primary particles 12 of the noble metal are post-supported on secondary particles 14 formed by agglomerating the primary particles 11 of the double oxide.

<Catalyst material adopting Ca as alkaline earth metal>
-Example 1-1
Zirconyl nitrate, neodymium nitrate, and calcium nitrate were dissolved in ion exchange water, and these aqueous solutions were mixed. By mixing the obtained mixed solution (acidic solution) with an 8-fold diluted solution of 28% by mass ammonia water as a basic solution and neutralizing it, a coprecipitate (Zr, Nd and Ca double oxide) Precursor) was obtained. The solution containing this coprecipitate is centrifuged to remove the supernatant (dehydration), and ion-exchanged water is further added and stirred (water washing). The basic solution was removed. After the final dehydration, the dinitrodiamine platinum nitric acid solution was added and mixed. Next, the obtained mixture was dried in the atmosphere at a temperature of 150 ° C. for a whole day and night, pulverized, and then calcined in the atmosphere at a temperature of 500 ° C. for 2 hours to thereby obtain the catalyst material of Example 1-1. Obtained.

In this case, since the coprecipitate (precursor of double oxide of Zr, Nd, and Ca) and the dinitrodiamine platinum nitric acid solution are mixed and dried and calcined, the obtained catalyst material is composed of Zr, Nd, and intermingled and the primary particles of the primary particles and Pt double oxide of Ca becomes those aggregation (Figure 5 shown to form status). The composition of the double oxide is CaO: ZrO ₂ : Nd ₂ O ₃ = 1.9: 86.6: 11.5 (molar ratio). That is, in this double oxide, the main component metal element is Zr, and it can be said that the double oxide of Zr and Nd is doped with Ca. The ratio between the double oxide and Pt is double oxide: Pt = 40: 1 (mass ratio). Hereinafter, the catalyst material of Example 1-1 is referred to as “Pt-doped Ca-doped ZrNdO”.

  The obtained catalyst material powder was mixed with a binder and ion-exchanged water to prepare a slurry. The filter body was immersed in the slurry from the inlet end, and suction was performed by an aspirator at the outlet end. Slurry that could not be removed by this suction was removed by air blowing from the inlet end face immersed in the mixed slurry. Thereby, the catalyst layer was formed in the filter main body. And after drying this at 150 degreeC in air | atmosphere, the sample for catalyst performance evaluation which concerns on Example 1-1 was obtained by carrying out heat baking (at the temperature of 500 degreeC for 2 hours) similarly in air | atmosphere.

The filter body is silicon carbide having a diameter of 17 mm, a length of 50 mm, a cell density of 178 per square inch (about 6.45 cm ² ), and a wall thickness separating the cells of 16 mils (about 0.4 mm). A product made of SiC) was used. The amount of catalyst material supported per liter of filter body is 20 g / L. Therefore, the amount of Pt supported is 0.5 g / L.

-Reference example 1-1-
Zirconyl nitrate, neodymium nitrate, and calcium nitrate were dissolved in ion exchange water, and these aqueous solutions were mixed. The resulting mixed solution (acidic solution) was neutralized by mixing an 8-fold diluted solution of 28% by mass ammonia water to obtain a coprecipitate. The solution containing this coprecipitate was repeatedly subjected to dehydration and water washing operations by centrifugation in the same manner as in Example 1-1, and the coprecipitate after dehydration was dried in the atmosphere at a temperature of 150 ° C. for one day and pulverized. Thereafter, firing was performed in the air at a temperature of 500 ° C. for 2 hours to obtain a double oxide powder of Zr, Nd, and Ca (generation of double oxide by coprecipitation method). The composition is CaO: ZrO ₂ : Nd ₂ O ₃ = 1.9: 86.6: 11.5 (molar ratio). That is, in this ZrNdCa double oxide, the main component metal element is Zr, and it can be said that the double oxide of Zr and Nd is doped with Ca.

A “nitrogen-plated Ca-doped ZrNdO” catalyst material according to Reference Example 1-1 was obtained by adding a dinitrodiamine platinum nitric acid solution to the ZrNdCa double oxide powder, mixing, and evaporating to dryness. The catalyst material is one primary particles of ZrNdCa mixed oxide primary particles of Pt to the secondary particles formed by aggregation is post-carried (shown to form state in Fig. 6). The ratio of the double oxide to Pt is double oxide: Pt = 40: 1 (mass ratio), as in Example 1-1.

The catalyst material was supported on the same filter body in the same manner as in Example 1-1 to form a catalyst layer, and a catalyst performance evaluation sample according to Reference Example 1-1 was obtained. The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

-Comparative Example 1-1
ZrNdO powder, which is a double oxide of Zr and Nd, was obtained from a mixed solution in which zirconyl nitrate and neodymium nitrate were dissolved in ion-exchanged water by the coprecipitation method described above. A dinitrodiamine platinum nitric acid solution and a calcium acetate solution were added to the ZrNdO powder, mixed, and evaporated to dryness, thereby obtaining a “Pt post-supported Ca post-supported ZrNdO” catalyst material according to Comparative Example 1-1. This catalyst material is obtained by post-supporting Pt and Ca on a ZrNd double oxide. The composition of this catalyst material excluding Pt is CaO: ZrO ₂ : Nd ₂ O ₃ = 1.9: 86.6: 11.5 (molar ratio), and the ratio of the total amount of components excluding Pt to Pt is 40. : 1 (mass ratio).

  The catalyst material powder was supported on the same filter body in the same manner as in Example 1-1 to obtain a catalyst performance evaluation sample according to Comparative Example 1-1. The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

-Comparative Example 1-2
Zirconyl nitrate and neodymium nitrate were dissolved in ion exchange water, and these aqueous solutions were mixed. The resulting mixed solution (acidic solution) was neutralized by mixing an 8-fold diluted solution of 28% by mass ammonia water to obtain a coprecipitate. About the solution containing this coprecipitate, operation of spin-drying | dehydration and water washing was repeated like Example 1-1, and the dinitrodiamine platinum nitric acid solution was added and mixed with the coprecipitate after dehydration. Next, the obtained mixture was dried in the air at a temperature of 150 ° C. for a whole day and night, pulverized, and then baked by holding it in the air at a temperature of 500 ° C. for 2 hours. A ZrNdO "catalyst material was obtained. This catalyst material is a double oxide of Zr, Nd, and Pt (no alkaline earth metal), and the composition excluding Pt is ZrO ₂ : Nd ₂ O ₃ = 88: 12 (molar ratio), and Pt The ratio is 2.5% by mass.

  The catalyst material powder was supported on the same filter body in the same manner as in Example 1-1 to obtain a catalyst performance evaluation sample according to Comparative Example 1-2. The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

-Comparative Example 1-3
ZrNdO powder was obtained in the same manner as Comparative Example 1-1. A dinitrodiamine platinum nitric acid solution was added to the ZrNdO powder, mixed, and evaporated to dryness to obtain a “post-Pt supported ZrNdO” catalyst material according to Comparative Example 1-3. This catalyst material is obtained by post-supporting Pt on a ZrNd double oxide (no alkaline earth metal). The composition of this catalyst material excluding Pt is ZrO ₂ : Nd ₂ O ₃ = 88: 12 (molar ratio), and the ratio of the total amount of components excluding Pt and Pt is 40: 1 (mass ratio).

  The catalyst material powder was supported on the same filter body in the same manner as in Example 1-1 to obtain a catalyst performance evaluation sample according to Comparative Example 1-3. The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

[Particulate combustion performance of catalyst materials]
In order to evaluate the particulate combustion performance of the catalyst materials of Example 1-1, Reference Example 1-1, and Comparative Examples 1-1 to 1-3, the carbon combustion rate was measured using the catalyst performance evaluation sample. did. Each sample was aged at a temperature of 800 ° C. for 24 hours in the air.

  First, ion exchange water was added to carbon black corresponding to 5 g / L, and the carbon black was sufficiently dispersed by stirring using a stirrer. The inlet end portion of the sample subjected to the aging treatment was immersed in the obtained slurry, and suction by an aspirator was performed from the outlet end portion. Moisture that could not be removed by this suction was removed by air blowing from the end face on the side immersed in the sample slurry. And the sample was dried by hold | maintaining at the temperature of 150 degreeC for 2 hours.

Each of the obtained samples was attached to a fixed bed type model gas flow device, and the gas temperature at the sample inlet was raised from normal temperature to 580 ° C. while N ₂ gas was allowed to flow through the sample. After the temperature stabilizes at 580 ° C., the gas composition is switched to “7.5% O ₂ +300 ppm NO + N ₂ (balance gas)” while maintaining the temperature, and the space velocity of the model gas is set to 40000 / h for the sample. Washed away. Then, by measuring the concentration of a model gas of CO and CO ₂ generated by the combustion of carbon was measured the time course of carbon combustion amount in the sample. And the carbon burning rate was calculated | required from the time required for carbon to burn 50%.

[Lattice oxygen release from catalyst material]
Each catalyst material (powder) of Example 1-1, Reference Example 1-1, and Comparative Examples 1-1 to 1-3 was subjected to aging that was maintained at a temperature of 800 ° C. for 24 hours in the air. The amount of lattice oxygen released was measured.

That is, after the catalyst material was compacted at a pressure of 25 tons, this was pulverized and screened to obtain a uniform particle size. 100 mg of the sized catalyst material was weighed and put in a quartz tube in a state of being sandwiched by silica wool from both sides. The catalyst material was heated to 580 ° C. while flowing He gas through the quartz tube, and then switched from He gas to 3.5% ¹⁸ O ₂ -containing He gas (flow rate: 100 cc / min) at the same temperature. In 600 seconds after this switching, various O ₂ species ( ¹⁶ O ₂ , ¹⁶ O ¹⁸ O, ¹⁸ O ₂ ) generated from ¹⁶ O of the catalyst material and ¹⁸ O in the gas are measured by a quadrupole mass spectrometer. The release amount of lattice oxygen atoms ( ¹⁶ O) was determined from the release amounts of ¹⁶ O ₂ and ¹⁶ O ¹⁸ O.

[result]
The results for the carbon burning rate are shown in Table 1 and FIG. 7, and the results for the lattice oxygen release amount are shown in Table 1 and FIG. The lattice oxygen release amount is expressed as a relative ratio based on the release amount of Comparative Example 1-3.

Looking at the carbon burning rate (Table 1 and FIG. 7), Ca-doped Example 1-1 and Reference Example 1-1 were obtained by comparing Ca-supported Comparative Example 1-1 and alkaline earth metal (Group 2A). The carbon burning rate is higher than that of Comparative Examples 1-2 and 1-3 which do not contain. From a comparison between Comparative Example 1-1 and Comparative Example 1-3, it can be seen that the carbon combustion rate increases when Ca is supported on a Zr-based double oxide. However, the reference example 1-1 has a higher carbon combustion rate than the comparative example 1-1. From this, it can be seen that doping Ca into the Zr-based double oxide is effective in increasing the carbon combustion rate. It is considered that the lattice oxygen release amount of the Zr-based double oxide is increased by Ca doping (Table 1 and FIG. 8). In addition, Example 1-1 has a higher carbon combustion rate than Reference Example 1-1 . From this, it can be seen that doping Pt with Zr-based double oxide is more advantageous for increasing the carbon combustion rate.

<Catalyst material adopting Sr as alkaline earth metal>
-Example 2-1
“Pt-doped Sr-doped ZrNdO” catalyst material and catalytic performance according to Example 2-1 (the form shown in FIG. 5 ) were adopted in the same manner as in Example 1-1 except that strontium nitrate was used instead of calcium nitrate . An evaluation sample was obtained. The composition of the double oxide constituting the catalyst material is SrO: ZrO ₂ : Nd ₂ O ₃ = 1.9: 86.6: 11.5 (molar ratio). In this double oxide, the main component metal element is Zr, and it can be said that the double oxide of Zr and Nd is doped with Sr. The ratio between the double oxide and Pt is double oxide: Pt = 40: 1 (mass ratio). The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

-Reference example 2-1-
“Pt post-supported Sr-doped ZrNdO” catalyst material and catalyst according to Reference Example 2-1 (the form shown in FIG. 6 ), except that strontium nitrate was used instead of calcium nitrate, and the others were the same as Reference Example 1-1 A sample for performance evaluation was obtained. The composition of the double oxide constituting the catalyst material is SrO: ZrO ₂ : Nd ₂ O ₃ = 1.9: 86.6: 11.5 (molar ratio). In this double oxide, the main component metal element is Zr, and it can be said that the double oxide of Zr and Nd is doped with Sr. The ratio between the double oxide and Pt is double oxide: Pt = 40: 1 (mass ratio). The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

-Reference Example 2-2-
The composition of the mixed oxide _{SrO: ZrO 2: Nd 2 O} 3 = 4.8: 83.8: 11.4 addition to such a (molar ratio) in the same manner as in Reference Example 2-1, Reference Example according to 2-2 to obtain a "Pt-post-supported Sr doped ZrNdO" catalyst material and the catalyst performance evaluation sample of (embodiment shown in FIG. 6).

-Reference example 2-3-
A mixed oxide powder of Zr, Nd, Sr, and Pr was obtained from a mixed solution in which zirconyl nitrate, neodymium nitrate, strontium nitrate, and praseodymium nitrate solution were dissolved in ion-exchanged water by the above-described coprecipitation method. The composition is SrO: ZrO ₂ : Nd ₂ O ₃ : Pr ₆ O ₁₁ = 1.9: 78.5: 13.7: 5.9 (molar ratio). That is, it can be said that this ZrNdPrSr double oxide has a main metal element of Zr, and the double oxide of Zr, Nd, and Pr is doped with Sr.

A “nitrogen-plated Sr-doped ZrNdPrO” catalyst material according to Reference Example 2-3 was obtained by adding a dinitrodiamine platinum nitric acid solution to the ZrNdPrSr double oxide powder, mixing, and evaporating to dryness. The catalyst material is one primary particles of ZrNdPrSr mixed oxide primary particles of Pt to the secondary particles formed by aggregation is post-carried (shown to form state in Fig. 6). The ratio between the double oxide and Pt is double oxide: Pt = 40: 1 (mass ratio).

The catalyst material was supported on the same filter body in the same manner as in Example 1-1 to form a catalyst layer, and a catalyst performance evaluation sample according to Reference Example 2-3 was obtained. The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

-Reference Example 2-4-
Reference Example 2 except that the composition of the double oxide is SrO: ZrO ₂ : Nd ₂ O ₃ : Pr ₆ O ₁₁ = 4.8: 76.2: 13.3: 5.7 (molar ratio) -3 , the “Pt post-supported Sr-doped ZrNdPrO” catalyst material according to Reference Example 2-4 (form shown in FIG. 6 ) and a catalyst performance evaluation sample were obtained.

-Reference Example 2-5-
Reference Example 2 except that the composition of the double oxide is SrO: ZrO ₂ : Nd ₂ O ₃ : Pr ₆ O ₁₁ = 9.5: 72.4: 12.7: 5.4 (molar ratio) -3 , the “Pt post-supported Sr-doped ZrNdPrO” catalyst material according to Reference Example 2-5 (form shown in FIG. 6 ) and a catalyst performance evaluation sample were obtained.

-Comparative Example 2-1
In place of calcium nitrate, strontium nitrate was employed, and in the same manner as in Comparative Example 1-1, a “Pt post-supported Sr post-supported ZrNdO” catalyst material and a catalyst performance evaluation sample according to Comparative Example 2-1 were obtained. . This catalyst material is obtained by post-supporting Pt and Sr on a ZrNd double oxide. The composition of this catalyst material excluding Pt is SrO: ZrO ₂ : Nd ₂ O ₃ = 1.9: 86.6: 11.5 (molar ratio), and the ratio of the total amount of components excluding Pt to Pt is 40. : 1 (mass ratio). The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

-Comparative Example 2-2
Double oxide powder of Zr, Nd, and Pr (containing no alkaline earth metal (Group 2A)) from a mixed solution of zirconyl nitrate, neodymium nitrate, and praseodymium nitrate solution in ion-exchanged water by the above-described coprecipitation method. Obtained. The composition is ZrO ₂ : Nd ₂ O ₃ : Pr ₆ O ₁₁ = 80.0: 14.0: 6.0 (molar ratio). A dinitrodiamine platinum nitric acid solution was added to the ZrNdPr double oxide powder, mixed, and evaporated to dryness to obtain a “post-Pt supported ZrNdPrO” catalyst material according to Comparative Example 2-2. The ratio between the double oxide and Pt is double oxide: Pt = 40: 1 (mass ratio).

  The catalyst material was supported on the same filter body by the same method as in Example 1-1 to form a catalyst layer, and a catalyst performance evaluation sample according to Comparative Example 2-2 was obtained. The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

[Particulate combustion performance of catalyst material / lattice oxygen release amount]
In order to evaluate the particulate combustion performance of each of the catalyst materials of Example 2-1 , Reference Examples 2-1 to 2-5 and Comparative Examples 2-1 and 2-2, the above-mentioned catalyst performance evaluation sample was used. The carbon burning rate was measured by the method described in 1. above. Each sample was aged at a temperature of 800 ° C. for 24 hours in the air. Moreover, after performing the aging which hold | maintains at the temperature of 800 degreeC in air | atmosphere for each catalyst material (powder) of the said Example 2-1, Reference example 2-1, and Comparative Example 2-1, it demonstrated previously. Each lattice oxygen release amount was measured by the method.

  The results are shown in Table 2, FIG. 9 (carbon combustion rate) and FIG. 10 (lattice oxygen release amount) together with the previous comparative examples 1-2 and 1-3.

Looking at the carbon burning rate (Table 2 and FIG. 9), the Sr-doped examples all have a higher carbon burning rate than the comparative examples without Sr post-supporting or alkaline earth metal (Group 2A). One possible reason is that the amount of lattice oxygen released from the Zr-based double oxide is increased by doping Sr (Table 2 and FIG. 10). Comparing Example 2-1 and Reference Example 2-1 , it can be seen that Pt dope has a larger effect of increasing the carbon combustion rate than the post-Pt support. From the comparison between Reference Examples 2-1 and 2-2 and Reference Examples 2-3 and 2-4 , it can be seen that the addition of Pr to the Zr-based double oxide increases the carbon combustion rate.

In Reference Examples 2-1 and 2-2 and Reference Examples 2-3 and 2-4 , the carbon combustion rate increases as the Sr doping amount increases. However, when the amount of Sr doping becomes excessive as in Reference Example 2-5 , the carbon combustion rate is lowered. From the relationship between the Sr doping amount and the carbon burning rate, the Sr doping amount in the double oxide should be 1% or more and 10% or less, particularly 1.9% or more and 4.5% or less, in mol%. It can be said that it is preferable. This is the same for other alkaline earth metals.

<Catalyst material adopting Ba as alkaline earth metal>
-Example 3-1
“Pt-doped Ba-doped ZrNdO” catalyst material and catalyst performance according to Example 3-1 (the form shown in FIG. 5 ) are employed in the same manner as Example 1-1 except that barium nitrate is used instead of calcium nitrate . An evaluation sample was obtained. The composition of the double oxide constituting the catalyst material is BaO: ZrO ₂ : Nd ₂ O ₃ = 1.9: 86.6: 11.5 (molar ratio). In this double oxide, the main component metal element is Zr, and it can be said that Ba is doped in the double oxide of Zr and Nd. The ratio between the double oxide and Pt is double oxide: Pt = 40: 1 (mass ratio). The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

-Reference example 3-1-
“Pt post-supported Ba-doped ZrNdO” catalyst material and catalyst according to Reference Example 3-1 (the form shown in FIG. 6 ), except that barium nitrate is used instead of calcium nitrate, and the others are the same as Reference Example 1-1 A sample for performance evaluation was obtained. The composition of the double oxide constituting the catalyst material is BaO: ZrO ₂ : Nd ₂ O ₃ = 1.9: 86.6: 11.5 (molar ratio). In this double oxide, the main component metal element is Zr, and it can be said that Ba is doped in the double oxide of Zr and Nd. The ratio between the double oxide and Pt is double oxide: Pt = 40: 1 (mass ratio). The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

-Comparative Example 3-1
Barium nitrate was used in place of calcium nitrate, and the others were the same as in Comparative Example 1-1, and the “Pt post-supported Ba post-supported ZrNdO” catalyst material and catalyst performance evaluation sample according to Comparative Example 3-1 were obtained. . This catalyst material is obtained by post-supporting Pt and Ba on a ZrNd double oxide. The composition of this catalyst material excluding Pt is BaO: ZrO ₂ : Nd ₂ O ₃ = 1.9: 86.6: 11.5 (molar ratio), and the ratio of the total amount of components excluding Pt to Pt is 40. : 1 (mass ratio). The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

[Particulate combustion performance of catalyst material / lattice oxygen release amount]
In order to evaluate the particulate combustion performance of the catalyst materials of Example 3-1 , Reference Example 3-1 and Comparative Example 3-1, the carbon burning rate was determined by the method described above using the catalyst performance evaluation sample. Was measured. Each sample was aged at a temperature of 800 ° C. for 24 hours in the air. Each catalyst material (powder) was aged at a temperature of 800 ° C. for 24 hours in the atmosphere, and then each lattice oxygen release amount was measured by the method described above.

  The results are shown in Table 3, FIG. 11 (carbon combustion rate) and FIG. 12 (lattice oxygen release amount) together with the previous comparative examples 1-2 and 1-3.

Looking at the carbon burning rate (Table 3 and FIG. 11), Ba-doped Example 3-1 and Reference Example 3-1 have a carbon burning rate higher than that of the comparative example without Ba-supported or alkaline earth metal (Group 2A). Is getting bigger. One possible reason is that the lattice oxygen release amount of the Zr-based double oxide is increased by doping with Ba (Table 3 and FIG. 12). Comparing Example 3-1 and Reference Example 3-1 , it can be seen that the effect of increasing the carbon combustion rate is greater in the Pt dope than in the post-Pt support.

<Catalyst material adopting Mg as alkaline earth metal>
-Example 4-1
“Pt-doped Mg-doped ZrNdO” catalyst material and catalyst of the first embodiment (FIG. 5) according to Example 4-1 are employed in the same manner as in Example 1-1 except that magnesium nitrate is used instead of calcium nitrate. A sample for performance evaluation was obtained. The composition of the double oxide is MgO: ZrO ₂ : Nd ₂ O ₃ = 1.9: 86.6: 11.5 (molar ratio). In this double oxide, the main component metal element is Zr, and it can be said that Mg is doped into the double oxide of Zr and Nd. The ratio between the double oxide and Pt is double oxide: Pt = 40: 1 (mass ratio). The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

-Reference example 4-1-
In the same manner as in Reference Example 1-1 , except that magnesium nitrate was used instead of calcium nitrate, the “Pt-supported Mg-doped ZrNdO” catalyst material of the second embodiment (FIG. 6) according to Reference Example 4-1 and A sample for catalyst performance evaluation was obtained. The composition of the double oxide constituting the catalyst material is MgO: ZrO ₂ : Nd ₂ O ₃ = 1.9: 86.6: 11.5 (molar ratio). In this double oxide, the main component metal element is Zr, and it can be said that Mg is doped into the double oxide of Zr and Nd. The ratio between the double oxide and Pt is double oxide: Pt = 40: 1 (mass ratio). The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

-Comparative Example 4-1
Magnesium nitrate was used instead of calcium nitrate, and in the same manner as in Comparative Example 1-1, a “Pt post-supported Mg post-supported ZrNdO” catalyst material and a sample for evaluating catalyst performance according to Comparative Example 4-1 were obtained. . This catalyst material is obtained by post-supporting Pt and Mg on a ZrNd double oxide. The composition of the catalyst material excluding Pt is MgO: ZrO ₂ : Nd ₂ O ₃ = 1.9: 86.6: 11.5 (molar ratio), and the ratio of the total amount of components excluding Pt to Pt is 40. : 1 (mass ratio). The catalyst material loading per 1 L of filter body is 20 g / L (Pt loading is 0.5 g / L).

[Particulate combustion performance of catalyst material / lattice oxygen release amount]
In order to evaluate the particulate combustion performance of each of the catalyst materials of Example 4-1, Reference Example 4-1, and Comparative Example 4-1, the carbon combustion rate was determined by the method described above using the catalyst performance evaluation sample. Was measured. Each sample was aged at a temperature of 800 ° C. for 24 hours in the air. Each catalyst material (powder) was aged at a temperature of 800 ° C. for 24 hours in the atmosphere, and then each lattice oxygen release amount was measured by the method described above.

  The results are shown in Table 4, FIG. 13 (carbon combustion rate) and FIG. 14 (lattice oxygen release amount) together with the previous comparative examples 1-2 and 1-3.

Looking at the carbon burning rate (Table 4 and FIG. 13), the Mg burning example 4-1 and the reference example 4-1 have a carbon burning rate higher than that of the comparative example without Mg post-supporting or alkaline earth metal (group 2A). Is getting bigger. One possible reason is that the amount of lattice oxygen released from the Zr-based double oxide increases due to Mg doping (Table 4 and FIG. 14). Comparing Example 4-1 and Reference Example 4-1 , it can be seen that the effect of increasing the carbon combustion rate is greater in the Pt dope than in the post-Pt support.

<X-ray diffraction chart of catalyst material>
Each of the catalyst materials of Examples 1-1, 2-1, 3-1 and 4-1, the double oxide “Ba-doped ZrNdO” (not including Pt) of Example 3-1, and Comparative Example 1-1 The crystal structure of the double oxide “ZrNdO” was examined by XRD (X-ray diffraction) analysis. The results are shown in FIG. All were subjected to the analysis after aging was carried out at a temperature of 800 ° C. for 24 hours in the air.

  The double oxide “Ba-doped ZrNdO” of Example 3-1 and the double oxide “ZrNdO” of Comparative Example 1-1 have almost the same X-ray diffraction profile, and no Ba diffraction peak is observed. From this, it can be seen that in “Ba-doped ZrNdO”, Ba is dissolved in the ZrNd double oxide. When Ba is dissolved in the ZrNd double oxide, the diffraction peak is considered to slightly shift from the diffraction peak of “ZrNdO”. However, in the case of “Ba-doped ZrNdO”, the shift is not recognized. This is presumably because the amount of Ba solid solution is small.

  The double oxide “Ca-doped ZrNdO” of Example 1-1 (excluding Pt), the double oxide “Sr-doped ZrNdO” of Example 2-1 (excluding Pt), and the double oxide of Example 4-1. Similarly to the double oxide “Ba-doped ZrNdO” of Example 3-1, the oxide “Mg-doped ZrNdO” (not including Pt) is a solution in which each of Ca, Sr, and Mg is dissolved in the ZrNd double oxide. is there.

  When the X-ray diffraction profile of the catalyst material “Pt-doped Ba-doped ZrNdO” of Example 3-1 is seen, a Pt diffraction peak appears despite the small amount of Pt. Therefore, Pt is not dissolved in the double oxide “Ba-doped ZrNdO” and is present at the crystal interface of the double oxide, that is, the catalyst material “Pt-doped Ba-doped ZrNdO” The primary particles of the oxide “Ba-doped ZrNdO” and the primary particles of Pt are mixed and agglomerated secondary particles, and at least a part of the Pt primary particles is exposed on the surface of the secondary particles. Can do. Since each of the catalyst materials of Examples 1-1, 2-1, and 4-1 also has almost the same profile as the catalyst material of Example 3-1, similarly, the primary particles of the double oxide and the primary particles of Pt Can be said to be mixed and agglomerated.

1 Filter 2 Exhaust gas inflow passage (exhaust gas passage)
3 Exhaust gas outflow passage (exhaust gas passage)
6 Fine pore (exhaust gas passage)
7 Catalyst layer 11 Primary particle of double oxide 12 Primary particle of noble metal 13 Secondary particle 14 Secondary particle

Claims (8)

A particulate material in which a catalyst layer is provided on a carrier substrate, and a catalyst material containing Zr, Nd, Ca, and a noble metal for burning particulate matter contained in engine exhaust gas is provided on the catalyst layer. A material combustion catalyst,
In the catalyst material, and the Zr, Nd, Ca form a mixed oxide, Ri main component metal element Zr der of the mixed oxide,
The primary particles of the double oxide and the primary particles of the noble metal are mixed together to form secondary particles, and at least part of the primary particles of the noble metal are exposed on the surface of the secondary particles. A particulate matter combustion catalyst characterized by comprising: A method for producing a particulate matter combustion catalyst, wherein a catalyst layer is provided on a carrier base material, and a catalyst material for burning particulate matter contained in engine exhaust gas is provided on the catalyst layer,
The basic solution was added to an acidic solution containing Zr ions and Nd ions and Ca ions, the solution of the noble metal in the resulting coprecipitate mixed, the catalyst material prepared by calcining the mixture, A method for producing a particulate material combustion catalyst material , comprising supporting the catalyst material on the carrier substrate . A particulate material in which a catalyst layer is provided on a carrier substrate, and a catalyst material containing Zr, Nd, Sr, and a noble metal for burning particulate matter contained in engine exhaust gas is provided on the catalyst layer. A material combustion catalyst,
In the catalyst material, and the Zr, Nd, Sr form a mixed oxide, Ri main component metal element Zr der of the mixed oxide,
The primary particles of the double oxide and the primary particles of the noble metal are mixed together to form secondary particles, and at least part of the primary particles of the noble metal are exposed on the surface of the secondary particles. A particulate matter combustion catalyst characterized by comprising: A method for producing a particulate matter combustion catalyst, wherein a catalyst layer is provided on a carrier base material, and a catalyst material for burning particulate matter contained in engine exhaust gas is provided on the catalyst layer,
The basic solution was added to an acidic solution containing Zr ions and Nd ions and Sr ions, the solution of the noble metal in the resulting coprecipitate mixed, the catalyst material prepared by calcining the mixture, A method for producing a particulate material combustion catalyst material , comprising supporting the catalyst material on the carrier substrate . A particulate material in which a catalyst layer is provided on a carrier substrate, and a catalyst material containing Zr, Nd, Ba, and a noble metal for burning particulate matter contained in engine exhaust gas is provided on the catalyst layer. A material combustion catalyst,
In the catalyst material, and the Zr and Nd and Ba form a mixed oxide, Ri main component metal element Zr der of the mixed oxide,
The primary particles of the double oxide and the primary particles of the noble metal are mixed together to form secondary particles, and at least part of the primary particles of the noble metal are exposed on the surface of the secondary particles. A particulate matter combustion catalyst characterized by comprising: A method for producing a particulate matter combustion catalyst, wherein a catalyst layer is provided on a carrier base material, and a catalyst material for burning particulate matter contained in engine exhaust gas is provided on the catalyst layer,
The basic solution was added to an acidic solution containing Zr ions and Nd ions and Ba ions, a solution of noble metal in the resulting coprecipitate mixed, the catalyst material is prepared by firing the mixture, A method for producing a particulate material combustion catalyst material , comprising supporting the catalyst material on the carrier substrate . A particulate material in which a catalyst layer is provided on a carrier base material, and a catalyst material containing Zr, Nd, Mg, and a noble metal for burning particulate matter contained in engine exhaust gas is provided on the catalyst layer. A material combustion catalyst,
In the catalyst material, and the Zr, Nd, Mg forms a mixed oxide, Ri main component metal element Zr der of the mixed oxide,
The primary particles of the double oxide and the primary particles of the noble metal are mixed together to form secondary particles, and at least part of the primary particles of the noble metal are exposed on the surface of the secondary particles. A particulate matter combustion catalyst characterized by comprising: A method for producing a particulate matter combustion catalyst, wherein a catalyst layer is provided on a carrier base material, and a catalyst material for burning particulate matter contained in engine exhaust gas is provided on the catalyst layer,
The basic solution was added to an acidic solution containing Zr ions and Nd ions and Mg ions, the solution of the noble metal in the resulting coprecipitate mixed, the catalyst material prepared by calcining the mixture, A method for producing a particulate material combustion catalyst material , comprising supporting the catalyst material on the carrier substrate .

Images