JP4841539B2 - Exhaust gas purification catalyst and method for producing the same - Google Patents

Description

  The present invention relates to an exhaust gas purification catalyst for purifying exhaust gas discharged from an internal combustion engine and a method for manufacturing the same.

An exhaust gas purifying catalyst generally has noble metal particles supported on the surface of particles made of a metal oxide, and contains harmful components such as unburned hydrocarbon (HC) and carbon monoxide ( CO) is oxidized with the noble metal particles and converted into water and CO ₂ gas which are harmless components.

  In recent years, exhaust gas regulations for automobiles are becoming more and more strict, and the above-mentioned unburned hydrocarbons (HC) and carbon monoxide (CO) can be purified with higher efficiency for exhaust gas purification catalysts. Is required. In order to meet such demands, various improvements have been made. For example, by utilizing the fact that the purification performance of the catalyst generally increases as the surface area of the noble metal particles increases, the surface area of the noble metal particles is increased by reducing the particle size of the noble metal particles in the exhaust gas purification catalyst. Thus, the surface energy is increased to improve the performance of the exhaust gas purifying catalyst.

  Here, the noble metal particles of the exhaust gas purifying catalyst are in an ultrafine particle state of several nm or less in the initial stage. However, while the exhaust gas purifying catalyst is actually used and exposed to a high-temperature oxidizing atmosphere, the surface of the noble metal particles is oxidized, and the adjacent noble metal particles aggregate and coalesce with each other, resulting in a coarseness of several tens of nm. There is a problem that the surface area of the noble metal particles is reduced and the purification rate of harmful substances is lowered with time.

  Noble metal colloids and metal alkoxides are used for exhaust gas purifying catalysts in which noble metal particles are uniformly dispersed throughout the catalyst layer formed on the inner surface of a carrier that has a large number of fine pores penetrated in a honeycomb shape to prevent aggregation of the noble metals. There is a method of producing a catalyst powder by mixing the metal alkoxide and hydrolyzing the metal alkoxide (Patent Document 1).

  Further, the reverse micelle method has been developed as a production method capable of producing noble metal particles having a large surface area with the aim of preventing the surface area from being reduced due to the coarsening of the noble metal particles and further increasing the activity. In this reverse micelle method, an emulsion solution in which a reverse micelle of an aqueous solution containing noble metal particle raw materials is formed in the course of the manufacturing process, and after precipitating the noble metal atomized in the reverse micelle, the reverse micelle is prepared. And the resulting precipitate is filtered, dried, pulverized, and calcined, and used as a catalyst.

Regarding this reverse micelle method, a reverse micelle solution containing a noble metal colloid aqueous solution inside the micelle, a reverse micelle solution containing a metal hydroxide aqueous solution inside the micelle, and a metal alkoxide are mixed, and the resulting mixture is baked. There exists a method of manufacturing a heat-resistant catalyst by this (patent document 2). Moreover, there is a method for producing a highly heat-resistant catalyst including a step of preparing a reverse micelle solution in which a noble metal salt aqueous solution and a metal salt aqueous solution as at least one kind of promoter component are simultaneously present (Patent Document 2).
JP 2000-15097 A JP 2005-111336 A JP 2005-185969 A

  However, the exhaust gas purification catalyst obtained by the method for producing a catalyst from a mixture of a noble metal colloid and a metal alkoxide is improved in the coarsening of the noble metal, but the pore volume of the catalyst powder is small. The catalyst layer in which the catalyst powder was coated on the carrier was dense, and the exhaust gas was difficult to diffuse in the catalyst layer.

  Moreover, the exhaust gas purifying catalyst obtained by the method using the reverse micelle method has a problem in terms of mass productivity because the manufacturing process becomes complicated and the manufacturing cost increases.

Exhaust gas purifying catalyst according to the present invention comprises a catalyst layer of at least one layer formed on the inner surface of the carrier, the catalyst layer includes a catalyst powder, the catalyst powder, and a noble metal, anchor material of the noble metal The first compound carrying a noble metal and the first compound carrying the noble metal are separated from the first compound carrying the noble metal and covering the periphery of the first compound carrying the noble metal. a second compound, made, the catalyst powder, the pore size has a first pore of the following range 0.1 [mu] m, the catalyst layer is between the catalyst powder, pore size 0.1μm~1μm And the pore volume of the second pore in the range of 0.1 μm to 1 μm is 10% to 60% among the pores having the pore diameter of 1 μm or less. It is a summary.

The method for producing an exhaust gas purifying catalyst according to the present invention is a method for producing the exhaust gas purifying catalyst according to the present invention, comprising: preparing a catalyst powder; and a catalyst layer containing the catalyst powder. Forming on the inner surface of the carrier, and preparing the catalyst powder includes supporting the noble metal on the first compound and dispersing the second compound or the precursor of the second compound in water. And a step of dispersing the first compound supporting the noble metal in the slurry of the second compound and drying and firing to obtain a catalyst powder, the catalyst layer on the inner surface of the carrier In the step of forming the catalyst powder, a compound that disappears during firing is added to the obtained catalyst powder to form a slurry, which is coated on the support, dried and fired, and the pores of the catalyst layer are in the range of 0.1 μm to 1 μm. Has a step of forming a catalyst layer having pores It is the gist of.

  According to the exhaust gas purifying catalyst of the present invention, the exhaust gas diffusibility can be ensured and the catalytic activity can be kept high.

  According to the method for producing an exhaust gas purification catalyst according to the present invention, the exhaust gas purification catalyst according to the present invention can be produced as designed.

  Hereinafter, embodiments of an exhaust gas purifying catalyst of the present invention will be described with reference to the drawings.

  FIG. 1 is a drawing for explaining the exhaust gas purifying catalyst according to the present invention supported on a carrier. A carrier 1 shown in a schematic perspective view as an example in FIG. 1A is made of a heat-resistant material such as ceramics, and has a substantially cylindrical shape having a number of fine holes penetrating from one end face to the other end face in a honeycomb shape. It has become. FIG. 1B shows an enlarged cross-sectional view of one cell of the carrier 1 indicated by a region B in FIG. As shown in FIG. 1 (b), a catalyst layer 10 is formed on an inner surface 1 a that partitions one cell of the carrier 1. It should be noted that the outer shape of the carrier 1 shown in FIG. 1 (a), the dimensions of the micropores, and the thickness of the catalyst layer 10 shown in FIG. 1 (b) are the actual carrier in order to facilitate understanding of the present invention. 1 and the catalyst layer 10 are different. Therefore, the exhaust gas purifying catalyst in the present invention is limited to the outer shape of the carrier 1 shown in FIG. 1 (a), the dimensions of the fine holes, and the thickness of the catalyst layer shown in FIG. 1 (b). is not.

  The exhaust gas purifying catalyst of this embodiment includes at least one catalyst layer 10. The catalyst layer 10 contains catalyst powder. The structure of the catalyst powder according to the present invention will be described with reference to FIG. 2 (a) and 2 (b) are schematic views of catalyst powder of the exhaust gas purifying catalyst according to the present invention. As shown in FIGS. 2 (a) and 2 (b), the catalyst powder 11 includes a noble metal 12, a first compound 13, and a second compound 14, and the noble metal 12 is a first metal. The single compound 13 or the aggregate of the first compound 13 supported on the compound 13 and the noble metal 12 is separated from each other by the second compound 14. In the exhaust gas purifying catalyst of the present invention, the catalyst layer 10 having the catalyst powder having such a structure has pores P1 provided in the catalyst powder and pores P2 as voids between the catalyst powders. Of the pores having a pore diameter of 1 μm or less, the pore volume of pores having a pore diameter in the range of 0.1 μm to 1 μm is 10% to 60%.

  In the exhaust gas purifying catalyst of the present embodiment shown in FIGS. 1 and 2, with respect to the catalyst powder 11 contained in the catalyst layer 10, the first compound 13 carries the noble metal 12 as shown in FIG. Yes. Thus, the first compound 13 acts as an anchor material for chemical bonding with the noble metal 12. Therefore, the first compound 13 suppresses the movement of the noble metal 12. Further, the periphery of the first compound 13 on which the noble metal 12 is supported is covered with a second compound 14 such as alumina. Accordingly, the second compound 14 physically suppresses the movement of the noble metal 12 away from the first compound 13. Further, the second compound 14 physically separates the first compounds 13 from each other, thereby preventing the first compounds 13 from moving, contacting, and aggregating. As a result, 1 prevents the noble metal 12 supported on the compound 13 from aggregating.

The catalyst powder 11 having the above structure requires the exhaust gas to reach the noble metal 12 by diffusion, and the inventors have applied the second compound that covers the noble metal 12 and the first compound 13 in the catalyst powder 11. No. 14 found that a certain range of voids was required. Specifically, as the initial pore volume of the catalyst 0.24 cm ³ / g or more, a degree 0.8 cm ³ / g or less. As an initial pore volume of the catalyst 0.24 cm ³ / If less than about g gas diffusivity of the exhaust gas is not sufficient, also the gas diffusion resistance exceeds about 0.8 cm ³ / g will not change.

  Further, regarding the catalyst layer 10 including the catalyst powder 11 having the above-described structure, the exhaust gas purifying catalyst of the present embodiment has a fine pore having a pore size of 1 μm or less. Of the pores, the pore volume of pores having a pore diameter in the range of 0.1 μm to 1 μm is required to be 10% to 60%.

FIG. 3 schematically shows a pore distribution curve of the catalyst layer of the exhaust gas purifying catalyst according to the present invention. In the pore distribution curve shown in FIG. 3, the pore volume in the range where the pore diameter exceeds 1 μm is due to surface defects, cracks, etc., and does not indicate the pores of the catalyst layer. Therefore, the pores of the catalyst layer are indicated by a pore volume having a pore diameter of 1 μm or less. The exhaust gas purifying catalyst of the present embodiment has a pore volume peak in each of a pore diameter range of 0.1 μm or less and a pore diameter range of 0.1 to 1 μm. The peak of the pore volume in the range where the pore diameter is 0.1 μm or less is considered to be the microscopic pore P1 included in the catalyst powder shown in FIG. Further, the peak of the pore volume in the range of the pore diameter of 0.1 to 1 μm is considered to be the pore P2 as the void between the catalyst powders shown in FIG. In the present invention, the pore P2 as a void between the catalyst powders is sufficiently secured by the pore volume of the pore having a pore diameter in the range of 0.1 μm to 1 μm being 10% to 60%. As a result, a sufficient path for the exhaust gas to diffuse in the catalyst layer is secured, so that the gas diffusibility can be improved. Note that the conventional example shown by a broken line in FIG. 3 has a single pore volume peak only in a range where the pore diameter is 0.1 μm or less. That is, the conventional example does not have a peak of the pore volume in the range of the pore diameter of 0.1 μm to 1 μm. In such a conventional example, the pore volume of pores having a pore diameter in the range of 0.1 μm to 1 μm is less than 10%, and the catalyst layer is dense, so that the exhaust gas is difficult to diffuse in the catalyst layer.

  In the exhaust gas purifying catalyst of this embodiment, when the catalyst powder 11 is coated on the carrier 1 to form the catalyst layer 10, the exhaust gas diffuses from the surface of the catalyst layer 10 to the deep part of the coated catalyst layer 10. In order to achieve this, among the pores having a pore diameter of 1 μm or less in the catalyst layer 10, the pores having a pore diameter in the range of 0.1 μm to 1 μm must occupy 10% to 60%. Limited to range. Excellent catalyst performance is obtained when the pore volume of the pores having a pore diameter in the range of 0.1 μm to 1 μm is in the range of 10% to 60%. If the pore volume of pores with a pore diameter in the range of 0.1 μm to 1 μm is less than 10% of the pore volume of pores with a pore diameter of 1 μm or less, the gas will not diffuse sufficiently and the catalyst particles of the present invention There is a possibility that the effect of improving the catalyst performance by the structure cannot be obtained sufficiently. In addition, among pores having a pore diameter of 1 μm or less, if the pore volume of a pore having a pore diameter in the range of 0.1 μm to 1 μm exceeds 60% of the pore volume of a pore having a pore diameter of 1 μm or less, Although sufficient from the viewpoint of diffusibility, the amount of voids in the diffusion layer is too large, and the strength of the diffusion layer may be reduced.

  When the pore volume of a pore having a pore diameter of 0.1 μm or less in the catalyst layer is A and the pore volume of a pore in the range of 0.1 μm to 1 μm is B, B is a pore volume having a pore diameter of 1 μm or less. It is preferable that it is 10%-60% of B, and B / A> = 0.1. When B / A is 0.1 or more, the exhaust gas easily passes through the catalyst layer, and the effect of improving gas diffusibility as expected in the present invention is obtained.

  The pore volume (B) of pores having a pore diameter in the range of 0.1 μm to 1 μm is more preferably 20% to 60% of the pore volume having a pore diameter of 1 μm or less. By being in the range of 20% to 60%, gas diffusibility is further improved, and catalyst performance is improved.

  The pore volume (B) of the pores having a pore diameter in the range of 0.1 μm to 1 μm is more preferably 30% to 50% of the pore volume having a pore diameter of 1 μm or less. By being in the range of 30% to 50%, particularly good gas diffusibility can be obtained, it is possible to achieve a good balance with good catalyst layer strength, and to achieve particularly excellent catalytic performance as an exhaust gas purifying catalyst. Can do.

  The ratio of the pore volume of the catalyst layer having a pore diameter in a specific range can be examined by measuring the pore distribution of the catalyst layer by a known method such as a mercury intrusion method.

The first compound 13 in the catalyst powder 11 can be composed of 70 wt% to 85 wt% of CeO ₂ and 15 wt% to 30 wt% of ZrO ₂ . When the first compound 13 mainly contains CeO ₂ , the first compound 13 has a composition in which CeO ₂ is 70 wt% to 85 wt% and ZrO ₂ is 15 wt% to 30 wt% (the total amount is 100%). %) Are suitable for exhaust gas purification. Particularly in the case of supporting Pt as the noble metal 12, as compared with the case of loading only CeO _2, better to carry a complex compound containing CeO ₂ and ZrO ₂ is, to improve performance. This is because the oxygen storage capacity is increased by containing ZrO ₂ . Further, by using a composite compound, the Pt adsorption force to the first compound 13 is increased, and Pt aggregation due to the thermal history of Pt can be suppressed. The effect of using such a composite compound is noticeable when ZrO ₂ is contained in an amount of 15 wt% or more. However, when ZrO ₂ is contained in an amount exceeding 30 wt%, the oxygen storage capacity of CeO ₂ is relatively weak. .

Further, the first compound 13 may be a composite compound having CeO ₂ and ZrO ₂ and further La ₂ O ₃ .

The first compound 13 in the catalyst powder 11 may be composed of 90 wt% to 99 wt% of ZrO ₂ and 1 wt% to 10 wt% of La ₂ O ₃ . When the first compound 13 mainly contains ZrO ₂ , the first compound 13 has a composition (total of 90 wt% to 99 wt% of ZrO ₂ and 1 wt% to 10 wt% of La ₂ O ₃ 100%) is suitable for exhaust gas purification. Particularly in the case of supporting Rh as the noble metal 12, the first compound 13 as compared with the case of loading only ZrO _2, is better to carry a complex compound containing ZrO ₂ and La ₂ O ₃ is preferred. This is the first compound 13 by containing La ₂ O ₃ in addition to ZrO _2, can suppress the aggregation of ZrO _2, is because it is possible to suppress the buried into between ZrO ₂ particles of Rh. Effect due to such a complex compound is remarkable by containing La ₂ O ₃ more than 1 wt%, the Rh and La ₂ O ₃ and melted is La ₂ O ₃ as comprising exceed 10 wt% There is a risk of covering.

  The second compound 14 in the catalyst powder 11 is preferably made of alumina. In order to purify the exhaust gas, it is necessary that the exhaust gas diffuses to the noble metal through the second compound 14, and alumina, particularly γ-alumina, is porous and has good gas diffusibility. Since it has excellent heat resistance, it is suitable for use as the second compound 14.

The second compound 14 in the catalyst powder 11 may be alumina containing CeO _{2 in an amount} of 5 wt% to 15 wt% and ZrO _{2 in an amount} of 3 wt% to 10 wt%. By including CeO ₂ or ZrO ₂ in the alumina, it is possible to suppress a decrease in performance after the endurance of the catalyst. This is because by adding CeO ₂ or ZrO ₂ to alumina, it is possible to suppress γ-alumina from becoming α-alumina, thereby suppressing deterioration (sintering phenomenon) of alumina due to thermal history. Even if one of CeO ₂ and ZrO ₂ is contained in alumina, it is possible to suppress the deterioration in performance after the endurance of the catalyst, but by including both CeO ₂ and ZrO ₂ , after the endurance of the catalyst The performance degradation can be more effectively suppressed. The content of CeO ₂ and ZrO ₂ in the alumina is preferably in the range of 5 wt% to 15 wt% of CeO ₂ and 3 wt% to 10 wt% of ZrO _{2. If} the lower limit of these ranges is not reached, CeO ₂ and ZrO ₂ In addition, if the content exceeds the upper limit of these ranges, there is a possibility that the performance deterioration after the endurance of the catalyst will be increased.

The second compound 14 in the catalyst powder 11 may be alumina containing 3 wt% to 10 wt% of La ₂ O ₃ . By including La ₂ O ₃ in the alumina, it is possible to suppress a decrease in performance after the durability of the catalyst. This is because by adding La ₂ O ₃ to alumina, deterioration (sintering phenomenon) of alumina due to thermal history can be suppressed. If the content of La ₂ O ₃ in the alumina is less than 3 wt%, the effect of adding La ₂ O ₃ is poor, and if it exceeds 10 wt%, the performance degradation after the endurance of the catalyst may increase. is there. Therefore, the content of La ₂ O ₃ in alumina is preferably in the range of 3 wt% to 10 wt%.

  The noble metal 12 in the catalyst powder 11 is preferably at least one selected from Pt, Pd and Rh. Pt, Pd, and Rh are all metals having catalytic activity for exhaust gas, and are suitable as the noble metal 12 supported on a compound such as Ce—Zr—Ox and Zr—LaOx suitable as the first compound 13. .

  The catalyst layer 10 containing the catalyst powder 11 as described above may have one layer formed on the inner surface 1a of the carrier 1, but a plurality of layers having different types of noble metals on the inner surface 1a of the carrier 1. It is more preferable that is formed. In a particularly preferred embodiment, a base layer to be described later is formed on the inner surface 1a of the carrier 1, and two catalyst layers having different types of noble metals are formed on the base layer. By forming a plurality of layers of different types of noble metals, the noble metals contained in each catalyst layer exhibit excellent exhaust gas purification performance, and the exhaust gas can be effectively discharged as a whole catalyst formed on the carrier 1. This is because it can be purified.

  When the catalyst layer 10 is formed in a plurality of layers on the inner surface 1 a of the carrier 1, it is more preferable to provide a base layer that does not contain a noble metal between the inner surface 1 a of the carrier 1 and the catalyst layer 10. By providing a base layer containing no noble metal on the inner surface 1 a side of the carrier 1 with respect to the catalyst layer 10, this base layer fills four corners of one cell having a quadrangular cross section defined by the inner surface 1 a of the carrier 1. Therefore, the thickness of the catalyst layer in contact with the base layer among the multiple layers of catalyst is made uniform, and the exhaust gas purification action of the catalyst layer can work effectively.

  The underlayer is preferably made of at least one of alumina and a hydrocarbon adsorbing compound. Alumina is a general material that supports the noble metal in the catalyst layer, and can be suitably used as an underlayer that does not contain the noble metal. Further, since the hydrocarbon-adsorbing compound is a base layer, the hydrocarbon contained in the exhaust gas can be adsorbed to the hydrocarbon-adsorbing compound of the base layer when the gasoline engine is started. Therefore, exhaust gas purification performance at the time of so-called cold start can be improved. Examples of this hydrocarbon adsorbing compound include zeolite and mesoporous silica.

When the catalyst layer 10 is formed in a plurality of layers on the inner surface 1a of the carrier 1, a suitable combination of the catalyst powder structures included in the catalyst layer on the inner surface side of the carrier is that the noble metal is at least one of Pt and Pd. The first compound is composed of 70 wt% to 85 wt% of CeO ₂ and 15 wt% to 30 wt% of ZrO ₂ , and the second compound is 5 wt% to 15 wt% of CeO ₂ , ZrO ₂ Is an alumina containing 3 wt% to 10 wt%. The catalyst layer on the inner surface side of the carrier means the first catalyst layer on the inner surface side of the carrier when there is no underlayer on the inner surface of the carrier and two catalyst layers are formed, When an underlayer is formed on the inner surface of the carrier, two catalyst layers are formed on the underlayer, and a total of three layers are formed on the inner surface of the carrier, an intermediate of the three layers in total. A layer (a layer on the inner surface side of the carrier among the two catalyst layers). It is preferable to make the catalyst powder of the catalyst layer on the inner surface side a combination of such a noble metal, the first compound and the second compound, since the catalytic performance of Pt and Pd can be sufficiently exhibited.

In the case where a plurality of catalyst layers 10 are formed on the inner surface 1a of the carrier 1, another preferred combination of the structure of the catalyst powder contained in the catalyst layer on the inner surface side of the carrier is that the noble metals are Pt and Pd. At least one, the first compound is composed of 70 wt% to 85 wt% of CeO ₂ and 15 wt% to 30 wt% of ZrO ₂ , and the second compound is composed of 3 wt% of La ₂ O ₃ It is an alumina containing 10 wt%. As the second compound of the catalyst powder in the catalyst layer of the inner surface, the CeO ₂ 5 wt% 15 wt% described above, instead of alumina containing _{ZrO 2 3wt% ~10wt%, 3wt} % of La ₂ O ₃ 10 wt Even if it is the combination made into the alumina containing%, since the catalyst performance of Pt and Pd can fully be exhibited, it is preferable.

When the catalyst layer 10 is formed in a plurality of layers on the inner surface 1a of the carrier 1, a suitable combination of the structures of the catalyst powder contained in the front catalyst layer is that the noble metal is Rh, and the first compound is ZrO ₂ is composed of 90 wt% to 99 wt%, La ₂ O ₃ is composed of 1 wt% to 10 wt%, and the second compound is alumina. The catalyst layer on the front side refers to the catalyst layer of the second layer far from the inner surface of the carrier when the base layer is not formed on the inner surface of the carrier and two catalyst layers are formed. When an underlayer is formed on the inner surface of the substrate, two catalyst layers are formed on the underlayer, and a total of three layers are formed on the inner surface of the carrier, the outermost layer of the total three layers (Of the two catalyst layers, the front layer). It is preferable that the catalyst powder of the catalyst layer on the front side be a combination of such a noble metal, the first compound, and the second compound, since the Rh catalyst performance can be sufficiently exhibited.

  The catalyst powder of the above-mentioned catalyst layer on the front side is preferably 40 wt% to 75 wt% of the first compound on which the noble metal is supported and 25 wt% to 60 wt% of the second compound. By setting the amount ratio of the first compound to the second compound within the above range, the front catalyst layer can effectively purify the exhaust gas.

  Next, an example of a preferred method for producing the exhaust gas purifying catalyst of the present invention will be described. The example of this manufacturing method has the process of preparing a catalyst powder, and the process of forming this catalyst powder on the inner surface of a support | carrier.

  Among these, the step of preparing the catalyst powder includes the step of supporting the noble metal on the first compound, the second compound or the precursor of the second compound dispersed in water, and if necessary, a cerium compound, zirconium A step of dissolving and slurrying at least one compound of a compound and a lanthanum compound; and thereafter, dispersing the first compound supporting the noble metal in the slurry of the second compound, drying and firing, and then catalyst powder The process of obtaining.

  As a method for supporting the noble metal on the first compound in the step of supporting the noble metal on the first compound, a conventionally known method can be used and is not particularly limited. For example, an impregnation method or the like can be applied.

  Separately from the step of supporting the noble metal on the first compound, the second compound or the precursor of the second compound is dispersed in water, and if necessary, at least one of a cerium compound, a zirconium compound and a lanthanum compound The seed compound is dissolved and slurried. The order of this step is not limited to the step of supporting the noble metal on the first compound. The second compound may be dispersed in water, or may be a precursor of the second compound. Further, when the second compound in the catalyst to be produced is a compound containing cerium, zirconium or lanthanum, the cerium compound or zirconium compound is dispersed in water in which the second compound or the precursor of the second compound is dispersed. And at least one compound of the lanthanum compound is dissolved.

  The first compound carrying a noble metal is dispersed in a slurry of the second compound or a precursor thereof in which at least one of a cerium compound, a zirconium compound and a lanthanum compound is dissolved as required. As such a dispersion treatment, that is, a treatment for dissolving the aggregate of the first compound supporting the noble metal and dispersing it in the second compound, there is a method using a dispersant of an organic compound. Further, a physical method using a homogenizer or a shearing force by high-speed stirring may be used.

It is made to dry after the above-mentioned dispersion | distribution process. The drying method is a drying method capable of maintaining the state in which the first compound supporting the noble metal is covered with the second compound, such as a method using a spray dryer or a vacuum freeze-drying method. a pore volume, 0.24 cm ³ / g or more, may be a drying method which can ensure less 0.8 cm ³ / g.

  Thereafter, it is fired to obtain a catalyst powder. The calcination conditions may be performed according to the general calcination conditions for the exhaust gas purifying catalyst.

  After the catalyst powder preparation step as described above, the catalyst powder is formed as a catalyst layer on the inner surface of the carrier. In this formation step, a compound that disappears upon firing is added to the obtained catalyst powder to form a slurry, which is coated on a support, dried and fired, and the pores of the catalyst layer are in the range of 0.1 μm to 1 μm. And a step of forming a catalyst layer having pores.

  The catalyst layer formed through this step needs to be a catalyst layer in which pores in the region of 0.1 μm to 1 μm have a specific ratio among the pores of the catalyst layer. Therefore, when slurrying the above-described catalyst powder and coating the support, a slurry is prepared by adding a compound that disappears upon firing after coating (hereinafter also referred to as “disappearing compound”) to the slurry. The added disappearance compound disappears when the prepared slurry is coated on the support and then baked. The disappeared portion contributes effectively to the formation of pores having a pore diameter of 0.1 μm to 1 μm in the catalyst layer. Examples of the disappearing compound include resin powder, starch, carbon black, activated carbon, and the like, and any compound that disappears upon firing may be used. As the disappearing compound, a powder having a particle diameter of 1 μm or less may be used, and a powder having a particle diameter of 1 μm or more may be used because it is pulverized to a particle diameter of 1 μm or less at the time of slurry preparation. Moreover, you may use a liquid thing like methylcellulose.

Examples 1-8, the proportion of pores of 0.1μ m ~1μ m of the catalyst layer formed on the support are different examples in various ways.

Example 1
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Place 118.42 g of acicular boehmite (10 nmφ × 100 nm) (containing 24% water) in a beaker, disperse in water and peptize with acid, add 90 g of cerium-zirconium composite oxide particles A prepared earlier, and speed up Dispersed by stirring. Thereafter, the slurry was dried and fired to prepare a powder a-1 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-1, 7 g of boehmite alumina, and 9.21 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-1 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-1).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 9.21 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. A slurry was obtained (slurry b-1).

  A slurry carrier a-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired, and a catalyst layer coated with 140 g / L was obtained. Thereafter, slurry b-1 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 1. The obtained sample of Example 1 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 2)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Place 118.42 g of acicular boehmite (10 nmφ × 100 nm) (containing 24% water) in a beaker, disperse in water and peptize with acid, add 90 g of cerium-zirconium composite oxide particles A prepared earlier, and speed up Dispersed by stirring. Thereafter, the slurry was dried and fired to prepare a powder a-1 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-1, 7 g of boehmite alumina, and 19.44 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-1 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-2).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 19.44 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-2).

  A slurry carrier a-2 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired, and a catalyst layer coated with 140 g / L was obtained. Thereafter, slurry b-2 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 2. The obtained sample of Example 2 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 3)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Place 118.42 g of acicular boehmite (10 nmφ × 100 nm) (containing 24% water) in a beaker, disperse in water and peptize with acid, add 90 g of cerium-zirconium composite oxide particles A prepared earlier, and speed up Dispersed by stirring. Thereafter, the slurry was dried and fired to prepare a powder a-1 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-1, 7 g of boehmite alumina, and 33.33 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-1 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-3).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 33.33 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry was obtained (slurry b-3).

  A slurry carrier a-3 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to form a catalyst layer coated with 140 g / L. Thereafter, slurry b-3 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 3. The obtained sample of Example 3 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

Example 4
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Place 118.42 g of acicular boehmite (10 nmφ × 100 nm) (containing 24% water) in a beaker, disperse in water and peptize with acid, add 90 g of cerium-zirconium composite oxide particles A prepared earlier, and speed up Dispersed by stirring. Thereafter, the slurry was dried and fired to prepare a powder a-1 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-1, 7 g of boehmite alumina, and 46.51 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-1 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-4).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 46.51 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle diameter of 3 μm. Slurry was obtained (slurry b-4).

  The slurry a-4 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired, and a catalyst layer coated with 140 g / L was obtained. Thereafter, slurry b-4 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 4. The obtained sample of Example 4 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 5)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Place 118.42g of acicular boehmite (10nmφx100nm) (containing 24% water) in a beaker, disperse in water and peptize with acid, add 90g of cerium-zirconium composite oxide particles A prepared previously, and stir at high speed. Dispersed. Thereafter, the slurry was dried and fired to prepare a powder a-1 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-1, 7 g of boehmite alumina, and 61.48 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-1 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-5).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 61.48 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-5).

  The slurry a-5 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired, and a catalyst layer coated with 140 g / L was obtained. Thereafter, slurry b-5 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 5. The obtained sample of Example 5 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 6)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Place 118.42 g of acicular boehmite (10 nmφ × 100 nm) (containing 24% water) in a beaker, disperse in water and peptize with acid, add 90 g of cerium-zirconium composite oxide particles A prepared earlier, and speed up Dispersed by stirring. Thereafter, the slurry was dried and fired to prepare a powder a-1 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-1, 7 g of boehmite alumina, and 75 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-1 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-6).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 75 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry b-6).

  A slurry carrier a-6 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-6 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 6. The obtained sample of Example 6 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 7)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. The particles were impregnated with dinitrodiamine Pd to obtain cerium-zirconium composite oxide particles carrying 0.85% Pd (this is referred to as cerium-zirconium composite oxide particles A2).

  Place 118.42 g of acicular boehmite (10 nmφ × 100 nm) (containing 24% water) in a beaker, disperse in water and peptize with acid, add 90 g of cerium-zirconium composite oxide particles A2 prepared earlier, and speed up Dispersed by stirring. Thereafter, the slurry was dried and fired to prepare a powder a-2 in which the cerium-zirconium composite oxide particles A2 were coated with alumina.

  168 g of this powder a-2, 7 g of boehmite alumina, and 33.3 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-2 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-7).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 33.3 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-7).

  A slurry carrier a-7 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to form a catalyst layer coated with 140 g / L. Thereafter, slurry b-7 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 7. The obtained sample of Example 7 is a catalyst carrying Pd: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 8)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. The particles were impregnated with dinitrodiamine Pd to obtain cerium-zirconium composite oxide particles carrying 0.85% Pd (this is referred to as cerium-zirconium composite oxide particles A2).

  Place 118.42 g of acicular boehmite (10 nmφ × 100 nm) (containing 24% water) in a beaker, disperse in water and peptize with acid, add 90 g of cerium-zirconium composite oxide particles A2 prepared earlier, and speed up Dispersed by stirring. Thereafter, the slurry was dried and fired to prepare a powder a-2 in which the cerium-zirconium composite oxide particles A2 were coated with alumina.

  168 g of this powder a-2, 7 g of boehmite alumina, and 46.51 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-2 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-8).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 46.51 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle diameter of 3 μm. Slurry (Slurry b-8).

  A honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mils was coated with slurry a-8, dried and fired to form a catalyst layer coated with 140 g / L. Thereafter, slurry b-8 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 8. The obtained sample of Example 8 is a catalyst carrying Pd: 0.5712 g / L and Rh: 0.2344 g / L.

  Examples 9 to 14 are examples in which the pore volume of the catalyst powder is variously different.

Example 9
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Place 118.42 g of acicular boehmite (10 nmφ × 100 nm) (containing 24% water) in a beaker, disperse in water and peptize with acid, add 90 g of cerium-zirconium composite oxide particles A prepared earlier, and speed up Dispersed by stirring. Thereafter, the slurry was dried and fired to prepare a powder a-1 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-1, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-1 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-11).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-11).

  The slurry a-11 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-11 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 9. The obtained sample of Example 9 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 10)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. The ceria zirconium particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particles A).

  Plate boehmite (20 × 20 × 10 nm) 113.92 g (containing 21% water) was placed in a beaker, dispersed in water and peptized with acid, and the previously prepared cerium-zirconium composite oxide particles A: 90 g In addition, it was dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare a powder a-4 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-4, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-4 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-12).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. Plate boehmite 113.92 g (containing 21% water) was placed in a beaker, dispersed in water and peptized with an acid, 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-3 in which particles B were coated with alumina.

  After adding 168 g of this powder b-3, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. A slurry was obtained (slurry b-12).

  A slurry carrier a-12 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to form a catalyst layer coated with 140 g / L. Thereafter, slurry b-12 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 10. The obtained sample of Example 10 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 11)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. The cerium-zirconium composite oxide particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles supporting 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Cube-like (20 × 20 × 20 nm) boehmite 105.88 g (containing 15% water) was placed in a beaker, dispersed in water and peptized with acid, and the previously prepared cerium-zirconium composite oxide particles A: 90 g In addition, it was dispersed by high-speed stirring. Thereafter, this slurry was dried and fired to prepare a powder a-5 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-5, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-5 was pulverized to obtain a slurry having an average particle diameter of 3 μm. (Slurry a-13).

  Next, zirconia lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. Cubic boehmite 105.88 g (containing 15% water) was placed in a beaker, dispersed in water and peptized with an acid, and 90 g of the previously prepared particles B were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-4 in which the particles B were coated with alumina.

  After adding 168 g of this powder b-4, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-13).

  A slurry carrier a-13 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to obtain a catalyst layer coated with 140 g / L. Thereafter, slurry b-13 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 11. The obtained sample of Example 11 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 12)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. The cerium-zirconium composite oxide particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles supporting 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  When 102.27 g of prismatic boehmite (20 × 20 × 60 nm) (containing 12% water) is placed in a beaker, dispersed in water and peptized with acid, the previously prepared cerium-zirconium composite oxide particles A: 90 g In addition, it was dispersed by high-speed stirring. Thereafter, this slurry was dried and fired to prepare a powder a-6 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-6, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-6 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-14).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 102.27 g of prismatic boehmite (containing 12% water) was dispersed in water and peptized with acid, and 90 g of the previously prepared particles B were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-5 in which the particles B were coated with alumina.

  After adding 168 g of this powder b-5, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-14).

  A slurry carrier a-14 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to obtain a catalyst layer coated with 140 g / L. Thereafter, slurry b-14 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 12. The obtained sample of Example 12 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 13)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. The cerium-zirconium composite oxide particles were impregnated with dinitrodiamine Pd to obtain cerium-zirconium composite oxide particles carrying 0.85% Pd (this is referred to as cerium-zirconium composite oxide particles A2).

  Plate boehmite (20 × 20 × 10 nm) 113.92 g (containing 21% water) was placed in a beaker, acidified by dispersing in water, and then added with 90 g of the cerium-zirconium composite oxide particles A2 prepared earlier. Dispersed by stirring. Thereafter, the slurry was dried and fired to prepare a powder a-7 in which the cerium-zirconium composite oxide particles A2 were coated with alumina.

  168 g of this powder a-7, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-7 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-15).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. Plate boehmite (20 × 20 × 10 nm) 113.92 g (containing 21% water) was placed in a beaker, dispersed in water and acidified, then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. . Thereafter, the slurry was dried and fired to prepare powder b-3 in which particles B were coated with alumina.

  After adding 168 g of this powder b-3, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. A slurry was obtained (slurry b-12).

  A slurry carrier a-15 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to obtain a catalyst layer coated with 140 g / L. Thereafter, slurry b-12 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 13. The obtained sample of Example 13 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 14)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. The particles were impregnated with dinitrodiamine Pd to obtain cerium-zirconium composite oxide particles carrying 0.85% Pd (this particle is referred to as particle A2).

  Place 105.88 g of cubic (20 × 20 × 20 nm) boehmite (containing 15% water) in a beaker, disperse in water and peptize with acid, add 90 g of the previously prepared particle A2 and disperse by high-speed stirring. I let you. Thereafter, the slurry was dried and fired to prepare a powder a-8 in which the particles A2 were coated with alumina.

  168 g of this powder a-8, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-8 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-16).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. Place 105.88 g of cubic (20 × 20 × 20 nm) boehmite (containing 15% water) into a beaker, disperse in water and peptize with acid, add 90 g of the previously prepared particle B, and disperse by high-speed stirring. I let you. Thereafter, the slurry was dried and fired to prepare powder b-4 in which the particles B were coated with alumina.

  After adding 168 g of this powder b-4, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-13).

  A slurry carrier a-16 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to form a catalyst layer coated with 140 g / L. Thereafter, slurry b-13 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 14. The obtained sample of Example 14 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

In Examples 15 to 17, the first compound is composed of CeO ₂ and ZrO ₂ , and the composite ratios of CeO ₂ and ZrO ₂ are variously different.

(Example 15)
As the first compound, cerium-zirconium composite oxide particles having 70% cerium and 30% zirconium were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is designated as particle A3).

  Place 105.88 g of cubic (20 × 20 × 20 nm) boehmite (containing 15% water) in a beaker, disperse in water and peptize with acid, add 90 g of the previously prepared particle A3, and disperse by high-speed stirring. I let you. Thereafter, the slurry was dried and fired to prepare powder a-11 in which the particles A3 were coated with alumina.

  168 g of this powder a-11, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-11 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-19).

  Next, zirconium lanthanum composite oxide particles of 90% zirconium and 10% lanthanum were impregnated with rhodium nitrate to prepare particles B2 carrying 0.814% rhodium. Place 105.88 g of cubic (20 × 20 × 20 nm) boehmite (containing 15% water) in a beaker, disperse in water and peptize with acid, add 90 g of the previously prepared particle B2 and disperse by high-speed stirring. I let you. Thereafter, the slurry was dried and calcined to prepare powder b-8 coated with particle B2 alumina.

  After adding 168 g of this powder b-8, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-17).

  The slurry a-19 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to form a catalyst layer coated with 140 g / L. Thereafter, slurry b-17 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 15. The obtained sample of Example 15 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 16)
As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is referred to as particle A4).

  Place 105.88 g of cubic (20 × 20 × 20 nm) boehmite (containing 15% water) in a beaker, disperse in water and peptize with acid, add 90 g of the previously prepared particle A4, and disperse by high-speed stirring. I let you. Thereafter, the slurry was dried and fired to prepare powder a-12 in which the particles A4 were coated with alumina.

  168 g of this powder a-12, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-12 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-20).

  Next, zirconium lanthanum composite oxide particles of 95% zirconium and 5% lanthanum were impregnated with rhodium nitrate to prepare particles B3 carrying 0.814% rhodium. Place 105.88 g of cubic (20 × 20 × 20 nm) boehmite (containing 15% water) in a beaker, disperse in water and peptize with acid, add 90 g of the previously prepared particle B3, and disperse by high-speed stirring. I let you. Thereafter, the slurry was dried and fired to prepare powder b-9 coated with particle B3 alumina.

  After adding 168 g of this powder b-9, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-18).

  The slurry a-20 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to obtain a catalyst layer coated with 140 g / L. Thereafter, slurry b-18 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 16. The obtained sample of Example 16 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 17)
As the first compound, cerium-zirconium composite oxide particles containing 85% cerium and 15% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is referred to as particle A5).

  Place 105.88 g of cubic (20 × 20 × 20 nm) boehmite (containing 15% water) in a beaker, disperse in water and peptize with acid, add 90 g of the previously prepared particle A5, and disperse by high-speed stirring. I let you. Thereafter, the slurry was dried and fired to prepare a powder a-13 in which the particles A5 were coated with alumina.

  168 g of this powder a-13, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-13 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-21).

  Next, a zirconium-lanthanum composite oxide particle of 99% zirconium and 1% lanthanum was impregnated with rhodium nitrate to prepare particle B4 carrying 0.814% rhodium. Place 105.88 g of cubic (20 × 20 × 20 nm) boehmite (containing 15% water) in a beaker, disperse in water and peptize with acid, add 90 g of the previously prepared particle B4, and disperse by high-speed stirring. I let you. Thereafter, the slurry was dried and fired to prepare powder b-10 coated with particle B4 alumina.

  After adding 168 g of this powder b-10, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-19).

  A slurry carrier was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to form a catalyst layer coated with 140 g / L. Thereafter, slurry b-19 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 17. The obtained sample of Example 17 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

Examples 18 to 20, the second compound is alumina containing the CeO ₂ and ZrO _2, the content of this CeO ₂ and ZrO ₂ are different variously.

(Example 18)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Add 101.46g of acicular boehmite (10nmφ × 100nm) (containing 24.6% water) to a beaker containing water, add cerium nitrate to 4.5g with cerium oxide, and oxidize zirconyl nitrate. When the zirconium was dispersed in water so as to be 9 g, 90 g of the cerium-zirconium composite oxide particles A prepared previously was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare a powder a-16 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-16, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-16 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-24).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-11).

  The slurry a-24 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to obtain a catalyst layer coated with 140 g / L. Thereafter, slurry b-11 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 18. The obtained sample of Example 18 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 19)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Add 101.46g of acicular boehmite (10nmφ × 100nm) (containing 24.6% water) to a beaker containing water, add cerium nitrate to 9g of cerium oxide, and add zirconyl nitrate to zirconium oxide. As a result, it was dispersed in water to 4.5 g, and 90 g of the cerium-zirconium composite oxide particles A prepared previously was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder a-17 in which cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-17, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-17 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-25).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-11).

  A catalyst carrier layer having a diameter of 36φ, 400 cell 6 mil honeycomb carrier (capacity 0.04L) coated with slurry a-25, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-11 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 19. The obtained sample of Example 19 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 20)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Add 111.14 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% moisture) to a beaker containing water, add cerium nitrate to 13.5 g of cerium oxide, and oxidize zirconyl nitrate. When dispersed in water to give 2.7 g of zirconium, 90 g of the previously prepared cerium-zirconium composite oxide particles A were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare a powder a-18 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-18, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-18 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-26).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-11).

  A catalyst carrier coated with slurry a-26 on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to form a catalyst layer coated with 140 g / L. Thereafter, slurry b-11 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 20. The obtained sample of Example 20 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

Examples 21 to 23, the second compound is alumina containing La ₂ O _3, this, the content of La ₂ O ₃ are different examples in various ways.

(Example 21)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Place 115.78 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 2.7 g of lanthanum oxide, and disperse in water. In addition, 90 g of the cerium-zirconium composite oxide particles A prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare a powder a-21 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-21, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-21 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-29).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-11).

  A catalyst carrier coated with slurry a-29 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to form a catalyst layer of 140 g / L. Thereafter, slurry b-11 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 21. The obtained sample of Example 21 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 22)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Place 113.40 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 4.5 g of lanthanum oxide, and disperse in water. In addition, 90 g of the cerium-zirconium composite oxide particles A prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and calcined to prepare powder a-22 in which cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-22, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-22 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-30).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-11).

  The slurry a-30 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to obtain a catalyst layer coated with 140 g / L. Thereafter, slurry b-11 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 22. The obtained sample of Example 22 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 23)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Place 107.43 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 9 g of lanthanum oxide, and disperse in water. The cerium-zirconium composite oxide particles A prepared previously: 90 g were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare a powder a-23 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-23, 7 g of boehmite alumina, and 52.27 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-23 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-31).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 52.27 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry (Slurry b-11).

  A slurry carrier a-31 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to form a catalyst layer coated with 140 g / L. Thereafter, slurry b-11 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 23. The obtained sample of Example 23 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

Examples 24 to 27 are examples in which an underlayer is provided and the second compound of the catalyst in the intermediate layer is alumina containing CeO ₂ and ZrO ₂ .

(Example 24)
After adding 180 g of γ-alumina powder and 20 g of boehmite alumina to a ball mill, 282.5 g of water and 17.5 g of 10% nitric acid were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry c-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is referred to as particle A4).

  Add 101.46g of acicular boehmite (10nmφ × 100nm) (containing 24.6% water) to a beaker containing water, add cerium nitrate to 9g of cerium oxide, and add zirconyl nitrate to zirconium oxide. As a result, it was dispersed in water to give 4.5 g, and 90 g of cerium-zirconium composite oxide particles A4 prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and calcined to prepare powder a-26 in which cerium-zirconium composite oxide particles A4 were coated with alumina.

  168 g of this powder a-26, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-26 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-34).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry was used (slurry b-31).

  The slurry c-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain an alumina layer of 50 g / L. Next, slurry a-34 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-31 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 24. The obtained sample of Example 24 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 25)
180 g of β zeolite, 288 g of silica sol (SiO2: 15%), and 32 g of water were added to a ball mill and then pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry d-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is referred to as particle A4).

  Add 101.46g of acicular boehmite (10nmφ × 100nm) (containing 24.6% water) to a beaker containing water, add cerium nitrate to 9g of cerium oxide, and add zirconyl nitrate to zirconium oxide. As a result, it was dispersed in water to give 4.5 g, and 90 g of cerium-zirconium composite oxide particles A4 prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and calcined to prepare powder a-26 in which cerium-zirconium composite oxide particles A4 were coated with alumina.

  168 g of this powder a-26, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-26 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-34).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry was used (slurry b-31).

  A slurry carrier d-1 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain a zeolite layer of 50 g / L. Next, slurry a-34 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-31 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 25. The obtained sample of Example 25 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 26)
After adding 180 g of γ-alumina powder and 20 g of boehmite alumina to a ball mill, 282.5 g of water and 17.5 g of 10% nitric acid were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry c-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pd to obtain cerium-zirconium composite oxide particles carrying 0.85% of Pd (this is designated as particle A8).

  Add 101.46g of acicular boehmite (10nmφ × 100nm) (containing 24.6% water) to a beaker containing water, add cerium nitrate to 9g of cerium oxide, and add zirconyl nitrate to zirconium oxide. As a result, the cerium-zirconium composite oxide particles A5: 90 g prepared above were added to the mixture so as to be 4.5 g, and dispersed by high-speed stirring. Thereafter, this slurry was dried and calcined to prepare powder a-27 in which cerium-zirconium composite oxide particles A8 were coated with alumina.

  168 g of this powder a-27, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-27 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-35).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry was used (slurry b-31).

  The slurry c-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain an alumina layer of 50 g / L. Next, slurry a-35 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-31 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 26. The obtained sample of Example 26 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L, respectively.

(Example 27)
180 g of β zeolite, 288 g of silica sol (SiO2: 15%), and 32 g of water were added to a ball mill and then pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry d-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pd to obtain cerium-zirconium composite oxide particles carrying 0.85% of Pd (this is designated as particle A8).

  Add 101.46g of acicular boehmite (10nmφ × 100nm) (containing 24.6% water) to a beaker containing water, add cerium nitrate to 9g of cerium oxide, and add zirconyl nitrate to zirconium oxide. As a result, it was dispersed in water so as to be 4.5 g, and 90 g of the cerium-zirconium composite oxide particles A8 prepared previously were added and dispersed by high-speed stirring. Thereafter, this slurry was dried and calcined to prepare powder a-27 in which cerium-zirconium composite oxide particles A8 were coated with alumina.

  168 g of this powder a-27, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-27 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-35).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry was used (slurry b-31).

  A slurry carrier d-1 was coated on a honeycomb carrier (capacity 0.04L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain a zeolite layer of 50 g / L. Next, slurry a-35 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-31 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 27. The obtained sample of Example 27 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

Examples 28 to 31 are examples in which an underlayer is provided and the second compound of the catalyst in the intermediate layer is alumina containing La ₂ O ₃ .

(Example 28)
After adding 180 g of γ-alumina powder and 20 g of boehmite alumina to a ball mill, 282.5 g of water and 17.5 g of 10% nitric acid were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry c-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is referred to as particle A4).

  Place 113.40 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 4.5 g of lanthanum oxide, and disperse in water. In addition, 90 g of cerium-zirconium composite oxide particles A4 prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare a powder a-30 in which the cerium-zirconium composite oxide particles A4 were coated with alumina.

  168 g of this powder a-30, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-30 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-38).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry was used (slurry b-31).

  A slurry carrier c-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain an alumina layer of 50 g / L. Next, slurry a-38 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-31 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 28. The obtained sample of Example 28 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L, respectively.

(Example 29)
180 g of β zeolite, 288 g of silica sol (SiO2: 15%), and 32 g of water were added to a ball mill and then pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry d-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is referred to as particle A4).

  Place 113.40 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 4.5 g of lanthanum oxide, and disperse in water. In addition, 90 g of cerium-zirconium composite oxide particles A4 prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare a powder a-30 in which the cerium-zirconium composite oxide particles A4 were coated with alumina.

  168 g of this powder a-30, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-30 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-38).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry was used (slurry b-31).

  The slurry d-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain a zeolite layer of 50 g / L. Next, slurry a-38 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-31 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 29. The obtained sample of Example 29 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 30)
After adding 180 g of γ-alumina powder and 20 g of boehmite alumina to a ball mill, 282.5 g of water and 17.5 g of 10% nitric acid were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry c-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pd to obtain cerium-zirconium composite oxide particles carrying 0.85% of Pd (this is designated as particle A8).

  Place 113.40 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 4.5 g of lanthanum oxide, and disperse in water. In addition, 90 g of the cerium-zirconium composite oxide particles A8 prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and calcined to prepare powder a-31 in which cerium-zirconium composite oxide particles A8 were coated with alumina.

  168 g of this powder a-31, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-31 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-39).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry was used (slurry b-31).

  A slurry carrier c-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain an alumina layer of 50 g / L. Next, slurry a-39 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-31 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 30. The obtained sample of Example 30 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 31)
180 g of β zeolite, 288 g of silica sol (SiO2: 15%), and 32 g of water were added to a ball mill and then pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry d-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pd to obtain cerium-zirconium composite oxide particles carrying 0.85% of Pd (this is designated as particle A8).

  Place 113.40 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 4.5 g of lanthanum oxide, and disperse in water. In addition, 90 g of the cerium-zirconium composite oxide particles A8 prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and calcined to prepare powder a-31 in which cerium-zirconium composite oxide particles A8 were coated with alumina.

  168 g of this powder a-31, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-31 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-39).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. In a beaker, 118.42 g of acicular boehmite (containing 24% water) was dispersed in water and peptized with an acid, and then 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-1 in which particles B were coated with alumina.

  After adding 168 g of this powder b-1, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry was used (slurry b-31).

  A slurry carrier c-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain an alumina layer of 50 g / L. Next, slurry a-39 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-31 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 31. The obtained sample of Example 31 is a catalyst carrying Pd: 0.5712 g / L and Rh: 0.2344 g / L.

Examples 28 to 31 are examples in which an underlayer is provided and the second compound of the catalyst in the intermediate layer is alumina containing La ₂ O ₃ .

  Examples 32-37 are examples in which an underlayer is provided and the ratio of the first compound and the second compound of the catalyst in the surface layer is variously different.

(Example 32)
After adding 180 g of γ-alumina powder and 20 g of boehmite alumina to a ball mill, 282.5 g of water and 17.5 g of 10% nitric acid were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry c-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is referred to as particle A4).

  Place 113.40 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 4.5 g of lanthanum oxide, and disperse in water. In addition, 90 g of cerium-zirconium composite oxide particles A4 prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare a powder a-30 in which the cerium-zirconium composite oxide particles A4 were coated with alumina.

  168 g of this powder a-30, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-30 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-38).

  Next, zirconium lanthanum (99: 1) composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B13 carrying 1.0175% rhodium. 142.1 g of acicular boehmite (containing 24% water) was placed in a beaker, dispersed in water and peptized with an acid, and 72 g of the previously prepared particle B13 was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-13 in which particles B were coated with alumina.

  After adding 168 g of this powder b-13, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry was used (Slurry b-41).

  A slurry carrier c-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain an alumina layer of 50 g / L. Next, slurry a-38 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-41 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 32. The obtained sample of Example 32 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 33)
After adding 180 g of γ-alumina powder and 20 g of boehmite alumina to a ball mill, 282.5 g of water and 17.5 g of 10% nitric acid were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry c-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is referred to as particle A4).

  Place 113.40 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 4.5 g of lanthanum oxide, and disperse in water. In addition, 90 g of cerium-zirconium composite oxide particles A4 prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare a powder a-30 in which the cerium-zirconium composite oxide particles A4 were coated with alumina.

  168 g of this powder a-30, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-30 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-38).

  Next, zirconium lanthanum (99: 1) composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B14 carrying 0.5814% rhodium. 71.1 g of acicular boehmite (containing 24% water) was placed in a beaker, dispersed in water and peptized with an acid, and then 126 g of the previously prepared particle B14 was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-14 in which particles B14 were coated with alumina.

  After adding 168 g of this powder b-14, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle diameter of 3 μm. Slurry was used (Slurry b-42).

  A slurry carrier c-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain an alumina layer of 50 g / L. Next, slurry a-38 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-42 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 33. The obtained sample of Example 33 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 34)
After adding 180 g of γ-alumina powder and 20 g of boehmite alumina to a ball mill, 282.5 g of water and 17.5 g of 10% nitric acid were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry c-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is referred to as particle A4).

  Place 113.40 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 4.5 g of lanthanum oxide, and disperse in water. In addition, 90 g of cerium-zirconium composite oxide particles A4 prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare a powder a-30 in which the cerium-zirconium composite oxide particles A4 were coated with alumina.

  168 g of this powder a-30, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-30 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-38).

  Next, zirconium lanthanum (99: 1) composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B15 carrying 0.5426% rhodium. 59.21 g of acicular boehmite (containing 24% water) was placed in a beaker, dispersed in water and peptized with an acid, and then the previously prepared particle B15: 135 g was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-15 in which particles B15 were coated with alumina.

  After adding 168 g of this powder b-15, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. Slurry was used (Slurry b-43).

  A slurry carrier c-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain an alumina layer of 50 g / L. Next, slurry a-38 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-43 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 34. The obtained sample of Example 34 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 35)
After adding 180 g of γ-alumina powder and 20 g of boehmite alumina to a ball mill, 282.5 g of water and 17.5 g of 10% nitric acid were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry c-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pd to obtain cerium-zirconium composite oxide particles carrying 0.85% of Pd (this is designated as particle A8).

  Place 113.40 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 4.5 g of lanthanum oxide, and disperse in water. In addition, 90 g of the cerium-zirconium composite oxide particles A8 prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and calcined to prepare powder a-31 in which cerium-zirconium composite oxide particles A8 were coated with alumina.

  168 g of this powder a-31, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-31 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-39).

  Next, zirconium lanthanum (99: 1) composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B14 carrying 0.5814% rhodium. 71.1 g of acicular boehmite (containing 24% water) was placed in a beaker, dispersed in water and peptized with an acid, and then 126 g of the previously prepared particle B14 was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-14 in which particles B14 were coated with alumina.

  After adding 168 g of this powder b-14, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle diameter of 3 μm. Slurry was used (Slurry b-42).

  A slurry carrier c-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain an alumina layer of 50 g / L. Next, slurry a-39 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-42 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 35. The obtained sample of Example 35 is a catalyst carrying Pd: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 36)
180 g of β zeolite, 288 g of silica sol (SiO2: 15%), and 32 g of water were added to a ball mill and then pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry d-1).

  As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is referred to as particle A4).

  Place 113.40 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 4.5 g of lanthanum oxide, and disperse in water. In addition, 90 g of cerium-zirconium composite oxide particles A4 prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare a powder a-30 in which the cerium-zirconium composite oxide particles A4 were coated with alumina.

  168 g of this powder a-30, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-30 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-38).

  Next, zirconium lanthanum (99: 1) composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B14 carrying 0.5814% rhodium. 71.1 g of acicular boehmite (containing 24% water) was placed in a beaker, dispersed in water and peptized with an acid, and then 126 g of the previously prepared particle B14 was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-14 in which particles B14 were coated with alumina.

  After adding 168 g of this powder b-14, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle diameter of 3 μm. Slurry was used (Slurry b-42).

  The slurry d-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain a zeolite layer of 50 g / L. Next, slurry a-38 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-42 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 36. The obtained sample of Example 36 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Example 37)
180 g of β zeolite, 288 g of silica sol (SiO2: 15%), and 32 g of water were added to a ball mill and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry d-1)
As the first compound, cerium-zirconium composite oxide particles containing 78% cerium and 22% zirconium were used. The particles were impregnated with dinitrodiamine Pd to obtain cerium-zirconium composite oxide particles carrying 0.85% of Pd (this is designated as particle A8).

  Place 113.40 g of acicular boehmite (10 nmφ × 100 nm) (containing 24.6% water) into a beaker containing water, add lanthanum nitrate to 4.5 g of lanthanum oxide, and disperse in water. In addition, 90 g of the cerium-zirconium composite oxide particles A8 prepared previously were added and dispersed by high-speed stirring. Thereafter, the slurry was dried and calcined to prepare powder a-31 in which cerium-zirconium composite oxide particles A8 were coated with alumina.

  168 g of this powder a-31, 7 g of boehmite alumina, and 38.41 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-31 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-39).

  Next, zirconium lanthanum (99: 1) composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B14 carrying 0.5814% rhodium. 71.1 g of acicular boehmite (containing 24% water) was placed in a beaker, dispersed in water and peptized with an acid, and then 126 g of the previously prepared particle B14 was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare powder b-14 in which particles B14 were coated with alumina.

  After adding 168 g of this powder b-14, 7 g of boehmite alumina, and 38.41 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added and pulverized to obtain an average particle diameter of 3 μm. Slurry was used (Slurry b-42).

  The slurry d-1 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain a zeolite layer of 50 g / L. Next, slurry a-39 was coated, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-42 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Example 37. The obtained sample of Example 37 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L, respectively.

  Comparative Examples 1 and 2 are examples to be compared with Examples 1-8.

(Comparative Example 1)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. The cerium-zirconium composite oxide particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles supporting 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

90 g of aluminum isopropoxide equivalent to 90 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, 90 g of cerium-zirconium composite oxide particles A were added thereto, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder a-3 in which particles A were coated with alumina. The alumina particle size was 7 to 8 nm.

  168 g of this powder a-3 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-3 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-9).

Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. 90 g equivalent of aluminum isopropoxide as Al ₂ O ₃ was dissolved in 2-methyl-2,4-pentanediol, 90 g of particles B were added, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-2 in which particles B were coated with alumina.

  After adding 168 g of this powder b-2 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm ( Slurry b-9).

  A honeycomb carrier (capacity 0.04L) with a diameter of 36φ, 400 mil, coated with 140g / L of slurry a-9, dried, then coated with 60g / L of slurry b-9 and dried, then at 400 ° C The sample of Comparative Example 1 was fired. The obtained sample of Comparative Example 1 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Comparative Example 2)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. The cerium-zirconium composite oxide particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles supporting 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

90 g of aluminum isopropoxide equivalent to 90 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, 90 g of cerium-zirconium composite oxide particles A were added thereto, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder a-3 in which particles A were coated with alumina. The alumina particle size was 7 to 8 nm.

  168 g of this powder a-3, 7 g of boehmite alumina, and 94.23 g of activated carbon powder were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-3 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-10).

Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. 90 g equivalent of aluminum isopropoxide as Al ₂ O ₃ was dissolved in 2-methyl-2,4-pentanediol, 90 g of particles B were added, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-2 in which particles B were coated with alumina.

  After adding 168 g of this powder b-2, 7 g of boehmite alumina, and 94.23 g of activated carbon powder to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain an average particle size of 3 μm. A slurry was obtained (slurry b-10).

  A slurry carrier a-10 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to form a catalyst layer coated with 140 g / L. Thereafter, slurry b-10 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Comparative Example 2. The obtained sample of Comparative Example 2 is a catalyst carrying Pd: 0.5712 g / L and Rh: 0.2344 g / L.

  Comparative Examples 3 and 4 are examples to be compared with Examples 9 to 14.

(Comparative Example 3)
As the first compound, cerium-zirconium composite oxide particles having a pore volume of 0.15 cm ³ / g were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as particle Aa).

Aluminum isopropoxide equivalent to 90 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, 90 g of the particles Aa were added thereto, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder a-9 in which the particles Aa were coated with alumina.

  168 g of this powder a-9 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-9 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-17).

Next, zirconium lanthanum composite oxide particles having a pore volume of 0.16 cm ³ / g were impregnated with rhodium nitrate to prepare particles Bb carrying 0.814% rhodium. 90 g of aluminum isopropoxide equivalent to 90 g as Al ₂ O ₃ was dissolved in 2-methyl-2,4-pentanediol, 90 g of the particle Bb was added thereto, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-6 in which the particles were coated with alumina.

  After adding 168 g of this powder b-6 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry). b-15).

  A slurry carrier a-17 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mils, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-15 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as the sample of Comparative Example 3. The obtained sample of Comparative Example 3 is a catalyst carrying Pd: 0.5712 g / L and Rh: 0.2344 g / L.

(Comparative Example 4)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. The cerium-zirconium composite oxide particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles supporting 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

  Place 90.9 g of alumina nanoparticles with an average particle size of 130 nm (containing 1% water) in a beaker, disperse in water and acidify, add 90 g of the cerium-zirconium composite oxide particles A prepared previously, and disperse by high-speed stirring. I let you. Thereafter, the slurry was dried and fired to prepare a powder a-10 in which the cerium-zirconium composite oxide particles A were coated with alumina.

  168 g of this powder a-10 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-10 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-18).

  Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. When 90.9 g of alumina nanoparticles having an average particle diameter of 130 nm (containing 1% of water) was placed in a beaker, dispersed in water and acidified, 90 g of the previously prepared particle B was added and dispersed by high-speed stirring. Thereafter, the slurry was dried and fired to prepare Powder b-7 in which the particles B were coated with alumina.

  After adding 168 g of this powder b-7 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm ( Slurry b-16).

  A catalyst carrier layer having a diameter of 36φ, 400 cell, 6 mil honeycomb carrier (capacity 0.04L) coated with slurry a-18, dried and fired to form a 140 g / L coated catalyst layer. Thereafter, slurry b-16 was coated, dried and fired to obtain a catalyst layer coated with 60 g / L. This was used as a sample of Comparative Example 4. The obtained sample of Comparative Example 4 is a catalyst carrying Pd: 0.5712 g / L and Rh: 0.2344 g / L.

  Comparative Examples 5 and 6 are examples to be compared with Examples 15 to 17.

(Comparative Example 5)
As the first compound, cerium-zirconium composite oxide particles having 60% cerium and 40% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is designated as particle A6).

90 g of aluminum isopropoxide equivalent to Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, 90 g of the particles A6 were added thereto, and water was added for hydrolysis. After water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, the powder a-14 in which the particles A6 were coated with alumina was prepared.

  168 g of this powder a-14 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-14 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-22).

Next, a zirconium-lanthanum composite oxide particle of 80% zirconium and 20% lanthanum was impregnated with rhodium nitrate to prepare particle B5 carrying 0.814% rhodium. 90 g equivalent of aluminum isopropoxide as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, 90 g of the particle B5 was added thereto, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-11 in which the particles B5 were coated with alumina.

  After adding 168 g of this powder b-11 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry). b-20).

  A slurry carrier a-22 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to form a 140 g / L catalyst layer. Thereafter, slurry b-20 was coated, dried and fired to obtain a 60 g / L catalyst layer. This was used as the sample of Comparative Example 5. The obtained sample of Comparative Example 5 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Comparative Example 6)
As the first compound, cerium-zirconium composite oxide particles having 90% cerium and 10% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is designated as particle A7).

90 g of aluminum isopropoxide equivalent to 90 g as Al ₂ O ₃ was dissolved in 2-methyl-2,4-pentanediol, 90 g of the particle A7 was added thereto, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder a-15 in which the particles A7 were coated with alumina.

  168 g of this powder a-15 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-15 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-23).

Next, 100% zirconium particles were impregnated with rhodium nitrate to prepare particles B6 carrying 0.814% rhodium. 90 g equivalent of aluminum isopropoxide as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, 90 g of the particle B6 was added thereto, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-12 in which particles B6 were coated with alumina.

  After adding 168 g of this powder b-12 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry). b-21).

  The slurry a-23 was coated on a honeycomb carrier (capacity 0.04 L) having a diameter of 36φ, 400 cells and 6 mil, dried and fired to obtain a 140 g / L catalyst layer. Thereafter, slurry b-21 was coated, dried and fired to obtain a 60 g / L catalyst layer. This was used as the sample of Comparative Example 6. The obtained sample of Comparative Example 6 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

  Comparative Examples 7 and 8 are examples to be compared with Examples 18-20.

(Comparative Example 7)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

Aluminum isopropoxide equivalent to 87.3 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, cerium acetylacetonate was added to 1.8 g with cerium oxide, and zirconium acetylacetate was added. Nart was added as zirconium oxide to 0.9 g, and 90 g of the particle A was added thereto, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder a-19 in which particles A were coated with alumina.

  168 g of this powder a-19 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added to the ball mill, and the powder a-19 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-27).

Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. 90 g equivalent of aluminum isopropoxide as Al ₂ O ₃ was dissolved in 2-methyl-2,4-pentanediol, 90 g of particles B were added, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-2 in which particles B were coated with alumina.

  After adding 168 g of this powder b-2 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm ( Slurry b-9).

  A honeycomb carrier (capacity 0.04L) with a diameter of 36φ, 400 cells, 6mil, coated with 140g / L of slurry a-27, dried, coated with 60g / L of slurry b-9, and then dried at 400 ° C. The sample of Comparative Example 7 was fired. The obtained sample of Comparative Example 7 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Comparative Example 8)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

Aluminum isopropoxide equivalent to 58.5 g as Al ₂ O ₃ is dissolved in 2-methyl 2,4 pentanediol, and cerium acetylacetonate is added to this so that it becomes 18 g with cerium oxide, and zirconium acetylacetonate is added. Was added to 13.5 g of zirconium oxide, 90 g of the particle A was added thereto, and water was added for hydrolysis. Water and organic matter such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder a-20 in which particles A were coated with alumina.

168 g of this powder a-20 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added to the ball mill, and powder a-20 was pulverized into a slurry with an average particle size of 3 μm (slurry a-28).
Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. 90 g equivalent of aluminum isopropoxide as Al ₂ O ₃ was dissolved in 2-methyl-2,4-pentanediol, 90 g of particles B were added, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-2 in which particles B were coated with alumina.

  After adding 168 g of this powder b-2 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm ( Slurry b-9).

  A honeycomb carrier (capacity 0.04L) with a diameter of 36φ, 400 cells, 6mil, coated with slurry a-28 140g / L, dried, then coated with slurry b-9 60g / L, dried, and then at 400 ° C The sample of Comparative Example 8 was fired. The obtained sample of Comparative Example 8 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

  Comparative Examples 9 and 10 are examples to be compared with Examples 21 to 23.

(Comparative Example 9)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

Aluminum isopropoxide equivalent to 89.1 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, and lanthanum acetate was added to 0.9 g as lanthanum oxide, and 90 g of particle A was added thereto. Water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder a-24 in which particles A were coated with alumina.

168 g of this powder a-24 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added to the ball mill, and the powder a-24 was pulverized into a slurry having an average particle diameter of 3 μm (slurry a-32).
Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. 90 g equivalent of aluminum isopropoxide as Al ₂ O ₃ was dissolved in 2-methyl-2,4-pentanediol, 90 g of particles B were added, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-2 in which particles B were coated with alumina.

  After adding 168 g of this powder b-2 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm ( Slurry b-9).

  A honeycomb carrier (capacity 0.04L) with a diameter of 36φ, 400 cells and 6mil is coated with 140g / L of slurry a-32, dried, then coated with 60g / L of slurry b-9, and then dried at 400 ° C. The sample of Comparative Example 9 was fired. The obtained sample of Comparative Example 9 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Comparative Example 10)
As the first compound, cerium-zirconium composite oxide particles having an average particle diameter of 30 nm were used. This particle was impregnated with dinitrodiamine Pt to obtain a cerium-zirconium composite oxide particle carrying 0.85% Pt (this is referred to as cerium-zirconium composite oxide particle A).

Aluminum isopropoxide equivalent to 76.5 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, and lanthanum acetate was added to 13.5 g as lanthanum oxide, and 90 g of the particles A were added thereto. Water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder a-25 in which particles A were coated with alumina.

168 g of this powder a-25 and 7 g of boehmite alumina were added to a ball mill. After that, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added to the ball mill, and the powder a-25 was pulverized into a slurry with an average particle size of 3 μm (slurry a-33)
Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. 90 g equivalent of aluminum isopropoxide as Al ₂ O ₃ was dissolved in 2-methyl-2,4-pentanediol, 90 g of particles B were added, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-2 in which particles B were coated with alumina.

  After adding 168 g of this powder b-2 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm ( Slurry b-9).

  After coating the slurry a-33 with 140g / L on a honeycomb carrier (capacity 0.04L) with a diameter of 36φ, 400 cells and 6 mil, dry it with 60g / L of slurry b-9, and then at 400 ° C The sample of Comparative Example 10 was fired. The obtained sample of Comparative Example 10 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

  Comparative Examples 11 and 12 are examples to be compared with Examples 24-27.

(Comparative Example 11)
As the first compound, cerium-zirconium composite oxide particles having 60% cerium and 40% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is designated as particle A6).

Aluminum isopropoxide equivalent to 87.3 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, cerium acetylacetonate was added to 1.8 g with cerium oxide, and zirconium acetylacetate was added. Nert was added as zirconium oxide to 0.9 g, 90 g of the particle A6 was added thereto, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder a-28 in which the particles A6 were coated with alumina.

168 g of this powder a-28 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added to the ball mill, and powder a-28 was pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry a-36).
Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. 90 g equivalent of aluminum isopropoxide as Al ₂ O ₃ was dissolved in 2-methyl-2,4-pentanediol, 90 g of particles B were added, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-2 in which particles B were coated with alumina.

  After adding 168 g of this powder b-2 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm ( Slurry b-9).

  A honeycomb carrier (capacity 0.04L) with a diameter of 36φ, 400 cells and 6mil is coated with 140g / L of slurry a-36, dried, then coated with 60g / L of slurry b-9, and then dried at 400 ° C. The sample of Comparative Example 11 was fired. The obtained sample of Comparative Example 11 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Comparative Example 12)
As the first compound, cerium-zirconium composite oxide particles having 90% cerium and 10% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is designated as particle A7).

Aluminum isopropoxide equivalent to 58.5 g as Al ₂ O ₃ is dissolved in 2-methyl 2,4 pentanediol, and cerium acetylacetonate is added to this so that it becomes 18 g with cerium oxide, and zirconium acetylacetonate is added. Was added to 13.5 g of zirconium oxide, 90 g of the particle A7 was added thereto, and water was added for hydrolysis. Water and organic matter such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder a-29 in which particles A7 were coated with alumina.

168 g of this powder a-29 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added to the ball mill, and the powder a-29 was crushed into a slurry with an average particle size of 3 μm (slurry a-37)
Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. 90 g equivalent of aluminum isopropoxide as Al ₂ O ₃ was dissolved in 2-methyl-2,4-pentanediol, 90 g of particles B were added, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-2 in which particles B were coated with alumina.

  After adding 168 g of this powder b-2 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm ( Slurry b-9).

  A honeycomb carrier (capacity 0.04L) with a diameter of 36φ, 400 cells and a capacity of 0.04L is coated with 140g / L of slurry a-37, dried, then coated with 60g / L of slurry b-9, and then dried at 400 ° C. The sample of Comparative Example 12 was fired. The obtained sample of Comparative Example 12 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

  Comparative Examples 13 and 14 are examples compared with Examples 28-31.

(Comparative Example 13)
As the first compound, cerium-zirconium composite oxide particles having 60% cerium and 40% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is designated as particle A6).

Aluminum isopropoxide equivalent to 89.1 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, and lanthanum acetate was added to 0.9 g as lanthanum oxide, and 90 g of particle A was added thereto. Water was added for hydrolysis. After water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, the powder a-32 in which the particles A6 were coated with alumina was prepared.

168 g of this powder a-32 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added to the ball mill, and the powder a-32 was pulverized into a slurry with an average particle diameter of 3 μm (slurry a-40)
Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. 90 g equivalent of aluminum isopropoxide as Al ₂ O ₃ was dissolved in 2-methyl-2,4-pentanediol, 90 g of particles B were added, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-2 in which particles B were coated with alumina.

  After adding 168 g of this powder b-2 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm ( Slurry b-9).

  A honeycomb carrier (capacity 0.04L) with a diameter of 36φ, 400 cells, 6mil, coated with 140g / L of slurry a-40, dried, then coated with 60g / L of slurry b-9, and then dried at 400 ° C. The sample of Comparative Example 9 was fired. The obtained sample of Comparative Example 9 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Comparative Example 14)
As the first compound, cerium-zirconium composite oxide particles having 90% cerium and 10% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is designated as particle A7).

Aluminum isopropoxide equivalent to 76.5 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, and lanthanum acetate was added to 13.5 g as lanthanum oxide, and 90 g of the particle A7 was added thereto. Water was added for hydrolysis. Water and organic matter such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder a-33 in which particles A7 were coated with alumina.

168 g of this powder a-33 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added to the ball mill, and powder a-33 was pulverized into a slurry with an average particle size of 3 μm (slurry a-41)
Next, zirconium lanthanum composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B carrying 0.814% rhodium. 90 g equivalent of aluminum isopropoxide as Al ₂ O ₃ was dissolved in 2-methyl-2,4-pentanediol, 90 g of particles B were added, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-2 in which particles B were coated with alumina.

  After adding 168 g of this powder b-2 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm ( Slurry b-9).

  A honeycomb carrier with a diameter of 36φ, 400 cells and 6 mil (capacity 0.04L) is coated with slurry a-41 and dried, then coated with slurry b-9 with 60g / L and dried, and then at 400 ° C. The sample of Comparative Example 14 was fired. The obtained sample of Comparative Example 14 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L, respectively.

  Comparative Examples 15 and 16 are examples compared with Examples 32-37.

(Comparative Example 15)
As the first compound, cerium-zirconium composite oxide particles having 60% cerium and 40% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is designated as particle A6).

Aluminum isopropoxide equivalent to 89.1 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, and lanthanum acetate was added to 0.9 g as lanthanum oxide, and 90 g of particle A was added thereto. Water was added for hydrolysis. After water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, the powder a-32 in which the particles A6 were coated with alumina was prepared.

168 g of this powder a-32 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added to the ball mill, and the powder a-32 was pulverized into a slurry with an average particle diameter of 3 μm (slurry a-40)
Next, zirconium lanthanum (99: 1) composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B16 carrying 0.50875% rhodium.

Aluminum isopropoxide equivalent to 36 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, 144 g of particle B16 was added thereto, and water was added for hydrolysis. Water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder b-16 in which particles B16 were coated with alumina.

  After adding 168 g of this powder b-16 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry). b-44).

  A honeycomb carrier with a diameter of 36φ, 400 cells and 6 mil (capacity 0.04L) was coated with slurry a-40 with 140g / L, dried, then coated with slurry b-44 with 60g / L, and then dried at 400 ° C. The sample of Comparative Example 15 was fired. The obtained sample of Comparative Example 15 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

(Comparative Example 16)
As the first compound, cerium-zirconium composite oxide particles having 90% cerium and 10% zirconium were used. The particles were impregnated with dinitrodiamine Pt to obtain cerium-zirconium composite oxide particles carrying 0.85% Pt (this is designated as particle A7).

Aluminum isopropoxide equivalent to 76.5 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, and lanthanum acetate was added to 13.5 g as lanthanum oxide, and 90 g of the particle A7 was added thereto. Water was added for hydrolysis. Water and organic matter such as 2-methyl-2,4-pentanediol were evaporated and dried, followed by firing to prepare powder a-33 in which particles A7 were coated with alumina.

168 g of this powder a-33 and 7 g of boehmite alumina were added to a ball mill. Thereafter, 307.5 g of water and 17.5 g of 10% nitric acid aqueous solution were added to the ball mill, and powder a-33 was pulverized into a slurry with an average particle size of 3 μm (slurry a-41)
Next, zirconium lanthanum (99: 1) composite oxide particles having an average particle diameter of 20 nm were impregnated with rhodium nitrate to prepare particles B17 carrying 1.356% rhodium.

An aluminum isopropoxide equivalent to 126 g as Al ₂ O ₃ was dissolved in 2-methyl 2,4 pentanediol, and 54 g of particles B17 were added thereto, and water was added for hydrolysis. After water and organic substances such as 2-methyl-2,4-pentanediol were evaporated and dried, the powder b-17 in which the particles B17 were coated with alumina was prepared.

  After adding 168 g of this powder b-17 and 7 g of boehmite alumina to a ball mill, 307.5 g of water and 17.5 g of a 10% nitric acid aqueous solution were added and pulverized to obtain a slurry having an average particle diameter of 3 μm (slurry). b-45).

  A honeycomb carrier (capacity 0.04L) with a diameter of 36φ, 400 cells and a capacity of 0.04L is coated with 140g / L of slurry a-41, dried, then coated with 60g / L of slurry b-45, and then dried at 400 ° C. The sample of Comparative Example 16 was fired. The obtained sample of Comparative Example 16 is a catalyst carrying Pt: 0.5712 g / L and Rh: 0.2344 g / L.

  Using the catalysts prepared according to Examples 1 to 37 and Comparative Examples 1 to 16, 5 catalysts per bank were installed in the exhaust system of a V-type engine with a displacement of 3500 cc. Using domestic regular gasoline, the catalyst inlet temperature was set to 650 ° C, and it was operated for 30 hours to give a heat history due to durability.

Furthermore, each exhausted catalyst is incorporated into a simulated exhaust gas distribution device, and the simulated exhaust gas having the composition shown in Table 1 is distributed to the simulated exhaust gas distribution device to raise the catalyst temperature at a rate of 30 ° C./min. The temperature (T50) at which the purification rate of CO and HC (C ₃ H ₆ ) was 50% was examined.

  Tables 2 to 9 show the pore volumes of the catalyst powders used in the catalysts of Examples 1 to 37 and Comparative Examples 1 to 16 by the gas adsorption method, and the honeycomb carrier was coated with a catalyst layer. A test piece is cut out from a sample, and the pore volume (A) of a pore having a pore diameter of 0.1 μm or less among pores having a pore diameter of 1 μm or less, which is obtained by a pore volume by mercury porosimetry, is obtained. The ratio of the pore volume (B) of the pores of 0.1 μm to 1 μm is also described. The evaluation results are also shown.

In addition, FIGS. 4 to 11 show the relationship between temperatures at which the HC (C ₃ H ₆ ) purification rate becomes 50% for the catalysts of Examples 1 to 37 and Comparative Examples 1 to 16.

  Comparative Example 1 shown in Table 2 and FIG. 4 uses alumina from aluminum isopropoxide as the second compound in the first layer catalyst, and aluminum isopropoxide as the second compound in the second layer catalyst. Although the catalyst uses propoxide, the pore volume of the catalyst powder of the first layer and the second layer is the smallest, and the ratio of the pores of 0.1 μm to 1 μm of the coated catalyst layer is as small as 9.3%. When the Pt particles after endurance were observed by TEM, the Pt particle size was about 10 nm, and the Pt particles were less aggregated. Moreover, there was little aggregation of Rh. However, the catalytic activity is low. This is thought to be due to the fact that although the Pt particle size is small, the pore volume is small and the exhaust gas is difficult to pass through, and the exhaust gas hardly reaches Pt.

  Comparative Example 2 shown in Table 2 and FIG. 4 uses the same powder as in Comparative Example 1 and increases the ratio of 0.1 μm to 1 μm pores of the coating layer to 65%. As a result, the coat layer was broken and could not be evaluated. This is presumably because the coating layer had too many voids and the strength of the coating layer was reduced.

  In contrast, Example 1 to Example 6, Example 9 to Example 12, Example 15 to Example 25, Example 28, 29, Example 32 to Example where the noble metal of the first layer is Pt. 34. In each catalyst of Example 36, the Pt particle diameter after durability was about 10 nm, and the aggregation of Pt particles was small. Further, the Rh particles were about 6 nm and there was little aggregation.

  In addition, Example 7, Example 8, Example 13, Example 14, Example 26, Example 27, Example 30, Example 31, Example 35, Example 37 where the noble metal of the first layer is Pd. , The Pd particle diameter after durability was as small as about 7 nm to 8 nm, and the aggregation of Pd particles was small. The Rh particles also had little aggregation at about 6 nm.

  The catalytic activity of these examples is much better than that of the comparative example, and high activity is obtained.

In Comparative Example 3 shown in Table 3 and FIG. 5, the cerium-zirconium composite oxide, which is the first compound in the first layer catalyst, has a pore volume of 0.15 cm ³ / g, and the first layer in the second layer catalyst. The compound used is a zirconium lanthanum composite oxide having a pore volume of 0.16 cm ³ / g, but the catalytic activity is low.

  In Comparative Example 4 shown in Table 3 and FIG. 5, alumina particles as large as 130 nm are used as the second compound in the catalyst of the first layer and the second layer. For this reason, the pore volume also takes a large value. Regarding the catalyst after endurance, when Pt particles were observed by TEM, the Pt particle size was increased to about 20 nm or more. Aggregation of Pt particles was confirmed, and aggregation of cerium-zirconium composite oxide particles was also observed. . This is because the alumina particles are large, the voids between the alumina particles are large, and the Pt-attached cerium-zirconium composite oxide particles move from the voids during endurance, causing the cerium-zirconium composite oxide particles to aggregate. Conceivable. It is considered that Pt also aggregated with the aggregation of the cerium-zirconium composite oxide particles, and the Pt particle diameter was increased. Also. The Rh particles in the second layer also showed an increase in particle size of 15 nm. For this reason, although the pore volume is large, it is considered that the activity of the catalyst is low.

  In Comparative Example 5 and Comparative Example 6 shown in Table 4 and FIG. 6, the composite ratio of cerium oxide and zirconium oxide or the like is changed as the first compound of the first layer and the second layer. In Comparative Example 5, the composite ratio of cerium oxide and zirconium oxide in the first layer is 60% and 40%, and the composite ratio of zirconium oxide and lanthanum oxide in the second layer is 80% and 20%. Compared with Examples 15, 16, and 17, the activity of the catalyst is low. The Pt particle size of the first layer was about 10 nm as observed by TEM. Although the Rh particles in the second layer were as small as about 6 nm, it was seen that zirconium lanthanum composite oxide particles were buried in agglomerated particles.

  Further, in Comparative Example 6, the composite ratio of cerium oxide and zirconium oxide in the first layer was 90% and 10%, and the second layer was 100% zirconium oxide, but compared to Examples 15, 16, and 17, The activity of the catalyst is low. The Pt particle size of the first layer was about 10 nm as observed by TEM. Although the Rh particles in the second layer were as small as about 6 nm, it was seen that the zirconium oxide particles were buried in agglomerated particles.

  This is presumably because, in addition to the small pore volume of the catalyst of Comparative Example 6, the oxygen releasing ability of the composite oxide of cerium oxide and zirconium oxide is inferior. Also, due to the composite ratio of zirconium oxide and lanthanum oxide, zirconium lanthanum composite oxide is likely to aggregate, and Rh particles are buried in zirconium lanthanum composite oxide particles and zirconium oxide particles, and contact with exhaust gas is prevented. It is thought that it became difficult.

  Moreover, since the pores of the catalyst layer are small, it is considered that the exhaust gas is difficult to reach and the catalyst activity is low.

  In Comparative Example 7 and Comparative Example 8 shown in Table 5 and FIG. 7, the catalytic activity is lower than in Examples 18, 19, and 20. In Comparative Example 7 and Comparative Example 8, when the Pt particles after durability were observed with TEM, the Pt particle size was about 10 nm and the aggregation of Pt particles was small. Moreover, there was little aggregation of Rh. However, the catalytic activity is low.

  In Examples 18, 19, and 20, by adding a cerium compound or a zirconium compound to the alumina precursor, the heat resistance of the alumina after firing is improved, and the pore volume after durability is kept large. Further, since the pores of 0.1 μm to 1 μm of the catalyst layer are secured, it is considered that the exhaust gas has good diffusibility and the catalytic activity is maintained.

  On the other hand, in Comparative Example 7 and Comparative Example 8, there is no effect of adding a cerium compound or a zirconium compound, the pore volume after durability cannot be secured, and the pores of the catalyst layer are also small, so that the exhaust gas is difficult to reach. Thus, it is considered that the catalytic activity is low.

  In Comparative Examples 9 and 10 shown in Table 6 and FIG. 8, compared with Examples 21, 22, and 23, the catalytic activity is low. When the Pt particles after endurance of Comparative Examples 9 and 10 were observed by TEM, the Pt particle size was about 10 nm and the aggregation of Pt particles was small. Moreover, there was little aggregation of Rh. However, the catalytic activity is low.

  In Examples 21, 22, and 23, by adding a lanthanum compound to the alumina precursor, the heat resistance of the alumina after calcination is improved, and the pore volume after durability is kept large. Further, since the pores of 0.1 μm to 1 μm of the catalyst layer are secured, the diffusibility of the exhaust gas is good, so that the catalytic activity is considered to be maintained.

  On the other hand, in Comparative Examples 9 and 10, there was no effect of adding a lanthanum compound, and the pore volume was small, so that the pore volume after durability could not be secured, and the pores of the catalyst layer were also small. It is conceivable that the gas is difficult to reach and the catalytic activity is low.

  In Comparative Example 11 and Comparative Example 12 shown in Table 7 and FIG. 9, the catalytic activity is lower than in Examples 24, 25, 26, and 27. When the endurance Pt particles of Comparative Example 11 and Comparative Example 12 were observed by TEM, the Pt particle size was about 10 nm and the aggregation of Pt particles was small. Moreover, there was little aggregation of Rh. However, the catalytic activity is low.

  In Examples 24, 25, 26, and 27, the catalyst layer has three layers, the lowermost layer is undercoated, and the intermediate and surface catalyst layers are coated. For this reason, the coat thickness of the catalyst of the intermediate layer is made uniform, and the catalyst works effectively. The same applies to the surface layer. Also, by adding a composite ratio of cerium oxide and zirconium oxide and adding a cerium compound or zirconium compound to the alumina precursor, the heat resistance of the alumina after firing is improved, and the pore volume after durability is kept large. The Further, since the pores of 0.1 μm to 1 μm of the catalyst layer are secured, it is considered that the exhaust gas has good diffusibility and the catalytic activity is maintained.

  On the other hand, Comparative Example 11 and Comparative Example 12 are due to the inferior oxygen releasing ability of the composite oxide of cerium oxide and zirconium oxide, and there is no effect of adding a cerium compound or a zirconium compound to the alumina precursor, It is conceivable that the pore volume after durability could not be secured and the pores of the catalyst layer were small, so that the exhaust gas was difficult to reach and the catalyst activity was low.

  In Comparative Example 13 and Comparative Example 14 shown in Table 8 and FIG. 10, the catalytic activity is lower than in Examples 28, 29, 30, and 31. When the Pt particles after endurance in Comparative Examples 13 and 14 were observed with TEM, the Pt particle size was about 10 nm, and the aggregation of Pt particles was small. Moreover, there was little aggregation of Rh. However, the catalytic activity is low.

  In Examples 28, 29, 30, and 31, the catalyst layer has three layers, the lowermost layer is undercoated, and the intermediate and surface catalyst layers are coated. For this reason, the coat thickness of the catalyst of the intermediate layer is made uniform, and the catalyst works effectively. The same applies to the surface layer. Further, by adding a compounding ratio of cerium oxide and zirconium oxide and a lanthanum compound to the alumina precursor, the heat resistance of the alumina after firing is improved, and the pore volume after durability is maintained large. Further, since the pores of 0.1 to 1 μm are secured in the catalyst layer, it is considered that the exhaust gas has good diffusibility and the catalytic activity is maintained.

  On the other hand, Comparative Example 13 and Comparative Example 14 are due to the inferior oxygen releasing ability of the composite oxide of cerium oxide and zirconium oxide, and there is no effect of adding the lanthanum compound to the alumina precursor. Since the pore volume cannot be secured and the pores of the catalyst layer are small, it is considered that the exhaust gas is difficult to reach and the catalyst activity is low.

  In Comparative Example 15 and Comparative Example 16 shown in Table 9 and FIG. 11, the catalytic activity is lower than in Examples 32, 33, 34, 35, 36, and 37.

  When Pt particles were observed by TEM in Comparative Example 15 after durability, the Pt particle size was about 10 nm and the Rh particles were as small as about 6 nm, but the zirconium lanthanum composite oxide particles were buried in agglomerated particles. The situation was seen. However, the catalytic activity is low.

  Further, when Pt particles were observed by TEM in Comparative Example 16 after durability, the Pt particle size was about 10 nm and the Rh particles were about 6 nm, but the catalytic activity was low.

  In Examples 32, 33, 34, 35, 36, and 37, the catalyst layer has three layers, the lowermost layer is undercoated, and the intermediate and surface catalyst layers are coated. For this reason, the coat thickness of the catalyst of the intermediate layer is made uniform, and the catalyst works effectively. The same applies to the surface layer. In addition, the composite ratio of cerium oxide and zirconium oxide in the intermediate layer and the addition of a lanthanum compound to the alumina precursor improve the heat resistance of the alumina after firing and maintain a large pore volume after durability. The Moreover, the compounding ratio of the zirconium composite oxide and alumina in the surface layer is also good. Since the pores of 0.1 μm to 1 μm of the catalyst layer are secured, it is considered that the exhaust gas has good diffusibility and the catalytic activity is maintained.

  On the other hand, in Comparative Example 15, the oxygen release ability of the composite oxide of cerium oxide and zirconium oxide in the intermediate layer was inferior, and there was no effect of adding the lanthanum compound to the alumina precursor. The pore volume cannot be secured, the surface layer cannot secure the pore volume after durability, the amount of alumina is small, and aggregation of the zirconium composite oxide cannot be suppressed, and Rh is buried in the zirconium composite oxide. The exhaust gas can no longer reach and the pores of the catalyst layer are small, so that it is difficult for the exhaust gas to reach and the catalyst activity is low.

  Further, in Comparative Example 16, the oxygen release ability of the composite oxide of cerium oxide and zirconium oxide in the intermediate layer was inferior, and there was no effect of adding the lanthanum compound to the alumina precursor, and the pore volume after durability In the surface layer, the pore volume after durability cannot be secured, and since the amount of alumina is large, agglomeration of the zirconium composite oxide can be suppressed and the aggregation of Rh can be suppressed, but there is much alumina. It is considered that the exhaust gas is difficult to reach and the pores of the catalyst layer are small, so that the exhaust gas is difficult to reach and the catalyst activity is low.

It is explanatory drawing of the support | carrier with which the exhaust gas purification catalyst which concerns on this invention is formed. 1 is a schematic view of an exhaust gas purifying catalyst according to the present invention. It is a graph which shows typically the pore distribution curve of the catalyst layer of the catalyst for exhaust gas purification concerning the present invention. It is a graph which shows the result of T50 of HC about the sample in an Example. It is a graph which shows the result of T50 of HC about the sample in an Example. It is a graph which shows the result of T50 of HC about the sample in an Example. It is a graph which shows the result of T50 of HC about the sample in an Example. It is a graph which shows the result of T50 of HC about the sample in an Example. It is a graph which shows the result of T50 of HC about the sample in an Example. It is a graph which shows the result of T50 of HC about the sample in an Example. It is a graph which shows the result of T50 of HC about the sample in an Example.

Explanation of symbols

1 Support 10 Catalyst Layer 11 Catalyst Powder 12 Precious Metal 13 First Compound 14 Second Compound

Claims (19)

Comprising at least one catalyst layer formed on the inner surface of the support;
The catalyst layer includes a catalyst powder, the catalyst powder,
With precious metals,
A first compound supporting a noble metal as the noble metal anchor material ;
A second compound that covers the periphery of the first compound supporting the noble metal and separates the first compound supporting the noble metal from the first compound supporting another noble metal ;
Consists of
The catalyst powder has first pores having a pore diameter of 0.1 μm or less,
The catalyst layer has second pores having a pore diameter ranging from 0.1 μm to 1 μm between the catalyst powders ,
The exhaust gas purifying catalyst, wherein the pore volume of the second pore in the range of 0.1 µm to 1 µm is 10% to 60% among the pores having a pore diameter of 1 µm or less in the catalyst layer . When the pore volume of the first pore having a pore diameter of 0.1 μm or less of the catalyst layer is A and the pore volume of the second pore in the range of 0.1 μm to 1 μm is B, B / A ≧ The exhaust gas purifying catalyst according to claim 1, wherein the exhaust gas purifying catalyst is 0.1. When the pore volume of the first pore having a pore diameter of 0.1 μm or less of the catalyst layer is A and the pore volume of the second pore in the range of 0.1 μm to 1 μm is B, B is the pore diameter. 3. The exhaust gas purifying catalyst according to claim 1, wherein the pore volume is 20% to 60% of the pore volume of 1 μm or less. When the pore volume of the first pore having a pore diameter of 0.1 μm or less of the catalyst layer is A and the pore volume of the second pore in the range of 0.1 μm to 1 μm is B, B is the pore diameter. 3. The exhaust gas purifying catalyst according to claim 1, wherein the pore volume is 30% to 50% of the pore volume of 1 μm or less. The catalyst powder pore volume, 0.24 cm ³ / g or more, 0.8 cm ³ / g exhaust gas purifying catalyst according to any one of claims 1 to 4, characterized in that less. The first compound of the catalyst powder, wherein the CeO ₂ is 70wt% ~85wt%, to any one of claims 1 to 5 ZrO ₂ is characterized by consisting of 15 wt% 30 wt% Exhaust gas purification catalyst. Wherein said first compound of the catalyst powder, ZrO ₂ and a 90wt% ~99wt%, any one of claims 1 to 5 La ₂ O ₃ is characterized in that it consists of a 1 wt% 10 wt% The exhaust gas purifying catalyst according to 1. The exhaust gas purifying catalyst according to any one of claims 1 to 7, wherein the second compound of the catalyst powder is made of alumina. The second compound of the catalyst powder, a CeO ₂ 5 wt% 15 wt%, to any one of claims 1 to 7, characterized in that the ZrO ₂ is alumina containing 3 wt% 10 wt% The catalyst for exhaust gas purification as described. The second compound of the catalyst powder, La ₂ O ₃ and 3 wt% 10 wt% exhaust gas purifying catalyst according to any one of claims 1 to 7, characterized in that alumina containing .   The exhaust gas purifying catalyst according to any one of claims 1 to 10, wherein the noble metal of the catalyst powder is at least one selected from Pt, Pd, and Rh. The exhaust gas purifying catalyst according to any one of claims 1 to 11, wherein a plurality of the catalyst layers are formed on an inner surface of the carrier.   The exhaust gas purifying catalyst according to claim 12, further comprising a base layer that does not contain a noble metal on the inner surface side of the carrier with respect to the catalyst layer.   The exhaust gas purifying catalyst according to claim 13, wherein the underlayer is made of at least one of alumina and a hydrocarbon adsorbing compound. Among the catalyst layers of the plurality of layers, the catalyst powder of the catalyst layer on the inner surface side of the support has a noble metal of at least one of Pt and Pd, the first compound is CeO ₂ of 70 wt% to 85 wt%, ZrO ₂ There are those comprising a 15 wt% 30 wt%, the second compound is 5 wt% 15 wt% of CeO _2, claim 12 or claims, characterized in that the ZrO ₂ is alumina containing 3 wt% 10 wt% Item 15. The exhaust gas purifying catalyst according to any one of Items 14 to 14 . Among the catalyst layers of the plurality of layers, the catalyst powder of the catalyst layer on the inner surface side of the support has a noble metal of at least one of Pt and Pd, the first compound is CeO ₂ of 70 wt% to 85 wt%, ZrO ₂ There are those comprising a 15 wt% 30 wt%, any one of claim 12 through claim 14 second compound is characterized in that the La ₂ O ₃ is alumina containing 3 wt% 10 wt% The exhaust gas purifying catalyst according to 1. Of the catalyst layer of the plural layers, the catalyst powder of the front of the catalyst layer, the noble metal is Rh, the first compound is ZrO ₂ and a _{90wt% ~99wt%, La 2 O} 3 and a 1 wt% 10 wt% and made of, the exhaust gas purifying catalyst according to any one of claims 12 to claim 14 second compound is characterized in that alumina.   Among the catalyst layers of the plurality of layers, the catalyst powder of the catalyst layer on the front side is characterized in that the first compound on which the noble metal is supported is 40 wt% to 75 wt%, and the second compound is 25 wt% to 60 wt%. The exhaust gas purifying catalyst according to claim 17. A method for producing the exhaust gas purifying catalyst according to any one of claims 1 to 18,
Preparing a catalyst powder, a catalyst layer including the catalyst powder and forming on the inner surface of the carrier,
The step of preparing the catalyst powder includes:
Supporting a noble metal on the first compound;
Dispersing the second compound or the precursor of the second compound in water to form a slurry;
A step of dispersing the first compound supporting a noble metal in the slurry of the second compound, drying and calcining to obtain a catalyst powder,
Forming the catalyst layer on the inner surface of the carrier,
To the obtained catalyst powder, a compound that disappears during firing is added to form a slurry, which is coated on a support, dried and fired, and a catalyst having pores in the region of 0.1 μm to 1 μm among the pores of the catalyst layer A method for producing an exhaust gas purifying catalyst, comprising a step of forming a layer.

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