JP6574670B2 - Exhaust gas purification catalyst - Google Patents

Description

  The present invention relates to an exhaust gas purifying catalyst.

Exhaust gas emitted from internal combustion engines such as automobiles contains harmful components such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NO _x ). The exhaust gas discharged from the diesel engine further contains harmful components such as sulfur oxide (SO _x ), particulate matter (PM), and soluble organic component (SOF).

Various catalyst technologies have been studied to purify these harmful components. For example, a diesel oxidation catalyst (DOC) oxidizes hydrocarbons and carbon monoxide and purifies them into harmless components such as water (H ₂ O) and carbon dioxide (CO ₂ ).

  In an automobile equipped with a diesel engine, the temperature of exhaust gas supplied to the diesel oxidation catalyst is a low temperature of about 100 to 200 ° C. during start-up, idling operation or low speed driving, and a high temperature of about 200 to 700 ° C. during high speed driving. It is. The diesel oxidation catalyst is required to be able to purify hydrocarbons and carbon monoxide with high efficiency over such a wide temperature range.

As a diesel oxidation catalyst, for example, in Patent Document 1, alumina (Al ₂ O ₃ ) supporting platinum (Pt) and zeolite are arranged in an upstream portion of a base material, and cerium dioxide supporting palladium (Pd). A diesel oxidation catalyst in which (CeO ₂ ) is arranged in the downstream part of the substrate is described. Patent Document 1 describes that this diesel oxidation catalyst exhibits excellent carbon monoxide purification performance at a temperature of less than 180 ° C.

JP 2014-117702 A

  In recent years, with the introduction of technology for improving fuel efficiency or design changes, exhaust gas at lower temperatures has been discharged from diesel engines. Therefore, there is a need for a technique that can achieve excellent carbon monoxide purification performance in a lower temperature range.

  Therefore, an object of the present invention is to provide an exhaust gas purifying catalyst having excellent carbon monoxide purifying performance in a low temperature range.

  According to an aspect of the present invention, the apparatus includes a base material and a catalyst layer supported by the base material, the catalyst layer including a first support made of alumina, platinum supported on the first support, and A first supported catalyst containing palladium, wherein the mass ratio of platinum to palladium is in the range of 2 to 7, the alloying rate of platinum and palladium is 40% or more, and the average particle size of platinum is 13 nm or less And a second supported catalyst comprising a second support made of a cerium-containing oxide having a cerium ratio of 15% by mass or more in all elements other than oxygen, palladium supported on the second support, and zeolite The ratio of palladium contained in the second supported catalyst to the total amount of platinum contained in the first supported catalyst and palladium contained in the second supported catalyst is in the range of 20 to 50% by mass. Exhaust gas purification touch There is provided.

  According to the present invention, an exhaust gas purifying catalyst excellent in carbon monoxide purifying performance in a low temperature range is provided.

1 is a perspective view schematically showing an exhaust gas purifying catalyst according to one embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of a structure that can be employed in the exhaust gas purification catalyst shown in FIG. 1. The figure which expands and shows the catalyst layer of the exhaust gas purification catalyst shown to FIG.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a perspective view schematically showing an exhaust gas purifying catalyst according to one embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of a structure that can be employed in the exhaust gas purifying catalyst shown in FIG. FIG. 3 is an enlarged view of the catalyst layer of the exhaust gas purifying catalyst shown in FIGS. 1 and 2.

  The exhaust gas-purifying catalyst 1 shown in FIGS. 1 and 2 is a monolith catalyst. The exhaust gas-purifying catalyst 1 is used as a catalyst for purifying exhaust gas discharged from a combustion engine.

For example, the exhaust gas-purifying catalyst 1 is used as a diesel oxidation catalyst (DOC) for purifying exhaust gas discharged from a diesel engine. In this case, typically, the exhaust gas-purifying catalyst 1 is combined with one or more of a diesel particulate filter (DPF), a selective catalytic reduction (SCR) system, and a NO _x storage reduction catalyst to form an exhaust gas purification system. Configure. This exhaust gas purification system may include the exhaust gas purification catalyst 1 in the most upstream part. Alternatively, the exhaust gas purification system may include the exhaust gas purification catalyst 1 downstream of the selective catalyst reduction system. Alternatively, the exhaust gas purification system may include the exhaust gas purification catalyst 1 at the most upstream part and downstream of the selective catalyst reduction system.

  The exhaust gas purification system may or may not include a device for regenerating a clogged diesel particulate filter, for example, a device for injecting fuel into exhaust gas discharged from a diesel engine. Good. However, the technique described here is particularly useful for an exhaust gas purification system that does not include such a regeneration device.

  Further, the technology described here is particularly useful for a combustion system including a diesel engine and an exhaust gas purification system, in particular, a combustion system in which the maximum temperature of exhaust gas supplied to the diesel oxidation catalyst is 550 ° C. or less.

  The exhaust gas-purifying catalyst 1 includes a substrate 2 such as a monolith honeycomb substrate. The substrate 2 is typically made of ceramics such as cordierite. The base material 2 includes through holes each extending in a direction substantially parallel to the flow direction of the exhaust gas.

  A catalyst layer 3 is formed on the partition walls of the substrate 2. As shown in FIG. 3, the catalyst layer 3 includes a mixture of a first supported catalyst 31, a second supported catalyst 32, and a zeolite 33.

  The first supported catalyst 31 includes a first support 311 and a first noble metal 312 supported on the first support 311. The first supported catalyst 31 has superior oxidation activity in a high temperature range as compared with the second supported catalyst 32.

  The first carrier 311 is made of alumina. Alumina is excellent in heat resistance and mechanical strength.

  The average particle diameter of the first carrier 311 is, for example, 1 to 15 μm, and typically 2 to 8 μm.

  The average particle diameter of the first carrier 311 is a value obtained by the following method. That is, five different surfaces of the catalyst layer 3 are photographed with a scanning electron microscope (SEM). The magnification is in the range of 1000 to 10,000 times. Then, ten of the first carriers 311 shown in each SEM image are selected at random and their areas are obtained. When a part of the selected first carrier 311 cannot be seen behind the other first carrier 311, the other first carrier 311 is randomly selected instead of the first carrier 311. As described above, the areas of the 50 first carriers 311 are obtained, and the average value thereof is calculated. Thereafter, the diameter of a circle having the same area as the previous average value is obtained. This diameter is taken as the average particle diameter of the first carrier 311.

  The first noble metal 312 is platinum and palladium. These platinum and palladium are supported on the first carrier 311. At least a part of platinum and at least a part of palladium form an alloy.

  Platinum plays a role in promoting the oxidation reaction of hydrocarbons and carbon monoxide. Palladium plays a supporting role in promoting the oxidation reaction of hydrocarbons and carbon monoxide, and also plays a role in suppressing platinum sintering.

  The mass ratio of platinum and palladium supported on the first carrier 311 is in the range of 2 to 7, typically in the range of 3 to 6, and preferably in the range of 4 to 6. When this mass ratio is reduced, sufficient purification performance tends to be difficult to obtain. When this mass ratio is increased, platinum sintering tends to occur easily.

  The alloying rate of platinum and palladium supported on the first carrier 311 is 40% or more, typically 55% or more, preferably 75% or more, and more preferably 80% or more. When this alloying rate is high, the effect of suppressing platinum sintering is great even when the mass ratio of platinum and palladium is large. In addition, the upper limit of this alloying rate is 100%, and according to an example, it is 82.5%.

  This alloying rate is determined by measurement using X-ray diffraction (XRD). The position of the diffraction peak of platinum obtained by measurement using X-ray diffraction shifts from the position of the diffraction peak obtained for platinum as a single metal when platinum is alloyed with palladium. In an alloy of platinum and palladium, a part of platinum atoms in the crystal lattice of platinum is substituted with palladium atoms. Since the palladium atom is smaller than the platinum atom, when a part of the platinum atom is replaced by the palladium atom, the plane spacing of the crystal lattice is reduced. By this reduction, the peak position of platinum changes to the high angle side. Therefore, by examining the degree of change in the peak position, it is possible to estimate the ratio of these alloys in the total amount of platinum and palladium.

Specifically, the alloying rate can be obtained from the following mathematical formula.
First, the diffraction angle of the first diffracted light obtained when the X-ray diffraction measurement for platinum as elemental metal and 2 [Theta] _1. Next, the rotation of the second diffracted light corresponding to the first diffracted light obtained when the X-ray diffraction measurement is performed on the platinum-palladium alloy having the same mass ratio as the platinum and palladium contained in the first supported catalyst. It is referred to as 2θ ₂ much trouble. The diffraction angle of the third diffracted light corresponding to the first diffracted light obtained when X-ray diffraction measurement is performed on the first supported catalyst is 2θ ₃ . The alloying rate is the ratio (θ ₃ −θ ₁ ) / (θ ₂ −θ ₁ ).

Specifically, this alloying rate can be obtained by the following procedure.
First, the first supported catalyst 31 is prepared as the sample SA3. Next, X-ray diffraction measurement is performed, and a diffraction angle 2θ ₃ is obtained for the sample SA3.

Next, a sample SA2 having an alloying rate of platinum and palladium of 100% is prepared. Specifically, the sample SA3 is heat-treated in air heated to 900 ° C. for 50 hours. Then, X-ray diffraction measurement is performed, and a diffraction angle 2θ ₂ is obtained for the sample SA2.

Next, a sample SA1 in which only platinum is supported on alumina is prepared. Then, X-ray diffraction measurement is performed to obtain a diffraction angle 2θ ₁ for the sample SA1.

From the diffraction angles 2θ ₁ , 2θ ₂ and 2θ ₃ thus obtained for the samples SA1 to SA3 and the above-described formula, the alloying rate of the sample SA3 is obtained.

  The average particle size of platinum supported on the first carrier 311 is 13 nm or less, typically 12 nm or less, preferably 11.5 nm or less, more preferably 11 nm or less, and even more preferably 10 nm. .5 nm or less. In addition, although there is no lower limit in this average particle diameter, it is 6 nm or more, for example, and is typically 8 nm or more.

  This average particle diameter can be determined by using X-ray diffraction measurement or CO pulse adsorption method. That is, X-ray diffraction measurement is performed on the first supported catalyst 31, a platinum peak is selected from the diffraction spectrum obtained thereby, and the average particle diameter is calculated using the Scherrer equation. When the particle size of the platinum particles is below the detection limit of the X-ray diffraction measurement, the average particle size is obtained using the CO pulse adsorption method. That is, the first supported catalyst 31 is measured by a CO pulse adsorption method, and the surface area of platinum is calculated from the amount of CO adsorption obtained thereby. Then, assuming that the platinum particles are spherical particles having the same particle diameter, the diameter of the particle is obtained from the calculated platinum surface area, platinum mass, and platinum specific gravity. This diameter is defined as the average particle diameter of platinum. The detection limit value of X-ray diffraction measurement is 7 nm.

  The ratio of the total amount of platinum and palladium in the first supported catalyst 31 is, for example, in the range of 1 to 15% by mass, and typically in the range of 2.5 to 9.0% by mass. When this ratio is small, sufficient purification performance tends not to be obtained. When this ratio is large, platinum and palladium sintering tends to occur easily.

  The second supported catalyst 32 includes a second carrier 321 and a second noble metal 322 supported on the second carrier 321. The second supported catalyst 32 has an excellent oxidation activity at a low temperature as compared with the first supported catalyst 31.

  The second carrier 321 contains a cerium-containing oxide. The cerium-containing oxide has an oxygen storage capacity (OSC), occludes oxygen in the fuel lean state, and releases oxygen stored in the fuel rich state. In the cerium-containing oxide, the ratio of cerium in all elements other than oxygen is 15% by mass or more, and typically 20% by mass or more.

  The cerium-containing oxide preferably further contains zirconium. Zirconium contributes to improving the heat resistance of the cerium-containing oxide.

  The cerium-containing oxide preferably further contains aluminum in addition to zirconium. When such a cerium-containing oxide is used, the purification performance of the second supported catalyst 32 tends to be improved.

  The cerium-containing oxide may be a complex oxide further containing a rare earth element other than cerium. The rare earth element is, for example, yttrium, neodymium, lanthanum, praseodymium, terbium, or a combination of two or more thereof. In this case, it is preferable that the cerium-containing oxide further contains zirconium.

  The average particle diameter of the second carrier 321 is, for example, 1 to 15 μm, and typically 2 to 8 μm. This average particle size is a value obtained by a method similar to the method for measuring the average particle size of the first carrier.

  The second noble metal 322 is palladium. Palladium is supported on the second carrier 321. Palladium plays a role in promoting the oxidation reaction of hydrocarbons and carbon monoxide.

  The average particle diameter of palladium supported on the second carrier 321 is, for example, 8 nm or less, typically 5 nm or less, and preferably 2 nm or less. In addition, although there is no lower limit in this average particle diameter, it is 0.5 nm or more, for example, and typically 0.8 nm or more.

  This average particle diameter can be determined using a CO pulse adsorption method. That is, the second supported catalyst 32 is measured by the CO pulse adsorption method, and the surface area of palladium is calculated from the CO adsorption amount obtained thereby. Then, assuming that the palladium particles are spherical particles having the same particle diameter, the diameter of the particle is obtained from the calculated palladium surface area, palladium mass, and palladium specific gravity. This diameter is defined as the average particle diameter of palladium.

  The amount of palladium in the second supported catalyst 32 is, for example, in the range of 0.5 to 5.0% by mass, and typically in the range of 0.8 to 3.0% by mass. When this ratio is reduced, sufficient purification performance tends to be difficult to obtain. When this ratio is increased, palladium sintering tends to occur.

  The ratio M1 / M2 between the mass M1 of the first supported catalyst 31 and the mass M2 of the second supported catalyst 32 is, for example, in the range of 0.1 to 1.5, typically 0.3 to 0.00. It is in the range of 8. When this ratio is increased, the purification performance of carbon monoxide in a low temperature range tends to decrease. When this ratio is reduced, the purification performance of carbon monoxide in the high temperature range tends to decrease.

  The proportion of palladium contained in the second supported catalyst 32 in the total amount of platinum contained in the first supported catalyst 31 and palladium contained in the second supported catalyst 32 is in the range of 20 to 50% by mass. It is in the range of 30 to 45% by mass, preferably in the range of 35 to 45% by mass, and more preferably in the range of 35 to 41% by mass. When the proportion of palladium contained in the second supported catalyst 32 is increased or decreased, the carbon monoxide purification performance in a low temperature range tends to be lowered.

The zeolite 33 adsorbs hydrocarbons in the exhaust gas.
The ratio M12 / M3 of the total mass M12 of the first supported catalyst 31 and the second supported catalyst 32 and the mass M3 of the zeolite 33 is, for example, in the range of 1.0 to 5.0, typically 1 Within the range of .5 to 3.5. When this ratio is reduced or increased, the purification performance in a low temperature range tends to be lowered.

  This exhaust gas-purifying catalyst 1 can be produced, for example, by the following method.

First, a treatment liquid containing platinum, palladium, and an organic base is prepared.
Specifically, for example, an acidic solution containing platinum and an acidic solution containing palladium are mixed. As an acidic solution containing platinum, for example, an aqueous platinum nitrate solution is used. As the acidic solution containing palladium, for example, a palladium nitrate aqueous solution is used. The concentration of platinum and the concentration of palladium in the mixed solution obtained by mixing these solutions are, for example, in the range of 1.0 to 15.0% and 0.5 to 10.0%, respectively.

  Next, while stirring the mixed solution, an aqueous solution containing an organic base at a concentration of 15 to 100% by mass is gradually added to the mixed solution until the pH of the mixed solution falls within the range of 8 to 14, for example. . And this liquid mixture is fully stirred.

  When an organic base is added to the above mixed solution, platinum and palladium are simultaneously precipitated, or first one of platinum and palladium is precipitated, and then the other of them is precipitated. Thereby, a complex of platinum and palladium is formed. These complexes precipitate, but are dispersed in the liquid in the form of extremely small particles by stirring while further adding an organic base. In this manner, a treatment liquid in which a complex of platinum and palladium is dispersed in the form of extremely small particles can be obtained. Hereinafter, the composite in the form of this particle is referred to as a composite particle.

  The organic base preferably has a low molecular weight. The molecular weight of the organic base is, for example, 30 to 500.

  Organic bases are, for example, diazabicycloundecene, diazabicyclononene, propylamine, methylamine, ethylamine, dimethylamine, triethylamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrahydroxide hydroxide. It is at least one selected from the group consisting of butylammonium, monoethanolamine, N, N-dimethyl-2-aminoethanol, 3-amino-1-propanol, and cyclohexylamine.

The particle diameter of the composite particles is, for example, 0.8 to 10 nm. The particle diameter of the composite particles can be determined by a dynamic light scattering method. The composite particles have a peak in a range of 550 to 700 cm ⁻¹ in a spectrum obtained by, for example, Raman spectroscopy.

  Next, the 1st supported catalyst 31 is prepared using this process liquid. Specifically, for example, alumina powder is added to the treatment liquid, nitric acid is added until the pH of the mixed liquid becomes 7 to 3, and this is sufficiently stirred. Next, this mixed solution is dried, and then calcined at 450 ° C. to 650 ° C. for 1 to 12 hours, for example, to obtain the first supported catalyst 31. Here, the baking treatment can be performed in the air or in an inert atmosphere. The inert atmosphere is, for example, nitrogen gas. When the firing treatment is performed in an inert atmosphere, the alloying rate of platinum and palladium supported on the first carrier 311 tends to be improved.

  Subsequently, the second supported catalyst 32 is prepared. Specifically, for example, an acidic solution containing palladium and a cerium-containing oxide powder are mixed and sufficiently stirred. Next, this mixed solution is dried, and then calcined in the atmosphere at 400 to 550 ° C. for 1 to 5 hours to obtain the second supported catalyst 32.

  The first supported catalyst 31 and the second supported catalyst 32 thus obtained and the zeolite 33 are dispersed in water, and a ball mill is used so that the average particle size of the dispersed particles becomes 2.0 to 8.0 μm. To prepare a slurry. Thereafter, the slurry is coated on the honeycomb substrate. And the exhaust gas purification catalyst 1 as a monolith catalyst is obtained by drying a coating layer and baking in air | atmosphere.

  The exhaust gas-purifying catalyst 1 obtained as described above exhibits excellent purification performance in a low temperature range. The reason is considered to be as described below, for example. Here, description will be made assuming that the combustion engine is a diesel engine.

  When the exhaust gas discharged from the diesel engine is at a low temperature, such as when traveling at a low speed, the zeolite 33 adsorbs hydrocarbons in the exhaust gas until it reaches an equilibrium state.

  As described above, the second supported catalyst 32 has an excellent oxidation activity at a lower temperature than the first supported catalyst 31. At low temperatures, the second noble metal 322 uses oxygen in the exhaust gas to promote the oxidation reaction of carbon monoxide and hydrocarbons in the exhaust gas when the oxygen concentration in the exhaust gas is sufficiently high. Is low, oxygen in the exhaust gas and oxygen released by the second carrier 321 are utilized to promote the oxidation reaction of carbon monoxide and hydrocarbons in the exhaust gas.

  The heat generated by this combustion raises the temperature of the first supported catalyst 31 in addition to raising the temperature of the second supported catalyst 32 itself. Since the first supported catalyst 31 and the second supported catalyst 32 are mixed in a single layer, heat is transferred to the second supported catalyst 32 uniformly and efficiently.

  The first supported catalyst 31 exhibits a higher oxidation activity at a lower temperature than a similar supported catalyst except that platinum and palladium do not form an alloy. Therefore, by supplying the above heat, the oxidation activity of the first supported catalyst 31 is also quickly improved. When the oxidation activity of the first supported catalyst 31 is improved in this way, the first supported catalyst 31 can efficiently oxidize and purify carbon monoxide and hydrocarbons in the exhaust gas, as with the second supported catalyst 32. Is possible. Therefore, the exhaust gas-purifying catalyst 1 exhibits excellent purification performance even at low temperatures.

  However, since the second carrier 321 is basic, the second supported catalyst 32 easily adsorbs the sulfur oxide that is an acidic substance. When the second supported catalyst 32 adsorbs a large amount of sulfur oxide, its oxidation activity decreases. In the exhaust gas-purifying catalyst 1, this problem is avoided as described below.

  When the exhaust gas reaches a high temperature, the zeolite 33 releases the adsorbed hydrocarbons. The first supported catalyst 31 promotes the oxidation of hydrocarbons released from the zeolite 33 more effectively than the second supported catalyst 32. Also, the first supported catalyst 31 promotes the oxidation of hydrocarbons and carbon monoxide in the exhaust gas more effectively than the second supported catalyst 32.

  As a result, heat is supplied from the first supported catalyst 31 to the second supported catalyst 32, and the temperature of the second supported catalyst 32 reaches a temperature sufficient for desorption of sulfur oxide, for example, 600 ° C. or higher. To do. Thereby, the adsorbed sulfur oxide is desorbed from the second supported catalyst 32, and the reduced oxidation activity of the second supported catalyst 32 is regenerated.

  Therefore, the exhaust gas-purifying catalyst 1 always exhibits excellent purification performance not only in a high temperature region but also in a low temperature region.

  Examples of the present invention will be described below.

<Manufacture of catalyst C1>
First, a platinum nitrate solution containing 1.531 g of platinum and a palladium nitrate solution containing 0.255 g of palladium were mixed and stirred for 5 minutes or more to obtain a mixed solution MS1.

  Next, a TMAH aqueous solution containing 1.53 g of tetramethylammonium hydroxide (TMAH) was added to the mixed solution MS1, and stirred for 10 minutes to prepare a treatment liquid L1.

  Thereafter, 60 g of alumina powder (manufactured by Sasol Limited) was added to the treatment liquid L1, and stirred for 10 minutes. Subsequently, nitric acid was added until the pH of the mixed solution reached 5.0 and stirred for 1 hour. Next, this mixed solution was dried at 120 ° C. for 6 hours or more, and then calcined at 600 ° C. for 10 hours in the air. As described above, the first supported catalyst 31 was obtained in the form of powder. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa1.

  The mass ratio of platinum to palladium in this supported catalyst SCa1 was 6.0.

For this supported catalyst SCa1, the alloying rate of platinum and palladium was measured by the method described above. That is, first, with respect to the supported catalyst SCa1, the diffraction angle 2θ _{3 of} platinum was measured using X-ray diffraction. Here, a sample horizontal strong X-ray diffractometer RINT-TTR III manufactured by Rigaku Corporation was used.

Next, a supported catalyst having an alloying ratio of platinum and palladium of 100% was prepared. Specifically, 60 g of alumina powder (manufactured by Sasol Limited) was added to the treatment liquid L1, and stirred for 10 minutes. Subsequently, nitric acid was added until the pH of the mixed solution reached 5.0 and stirred for 1 hour. Next, this mixed solution was dried at 120 ° C. for 6 hours or more, and then baked in the air at 900 ° C. for 50 hours. A supported catalyst was obtained as described above. Hereinafter, this supported catalyst is referred to as supported catalyst SCa1a. Next, with respect to the supported catalyst SCa1a, the diffraction angle 2θ _{2 of} platinum was measured using X-ray diffraction.

  Next, a supported catalyst supporting only platinum was prepared. Specifically, first, a mixed solution MS1b was obtained by the same method as described above for the mixed solution MS1 except that the nitric acid solution containing palladium was omitted.

  Next, a treatment liquid L1b was obtained by the same method as described above for the treatment liquid L1 except that the mixed solution MS1b was used instead of the mixed solution MS1.

Next, a supported catalyst was obtained by the same method as described above for the supported catalyst SCa1 except that the treatment liquid L1b was used instead of the treatment liquid L1. Hereinafter, this supported catalyst is referred to as supported catalyst SCa1b. Next, with respect to the supported catalyst SCa1b, the diffraction angle 2θ _{1 of} platinum was measured using X-ray diffraction.

From the platinum diffraction angles 2θ ₁ , 2θ _2, and 2θ ₃ thus obtained for the supported catalysts SCa1, SCa1a, and SCa1b, and the above formula, the alloying rate of platinum and palladium in the supported catalyst SCa1 was obtained. . As a result, the alloying rate was 82.5%.

  For the supported catalyst SCa1, the average particle size of platinum was measured by the method described above. As a result, the average particle size was 11 nm.

  Next, while stirring a palladium nitrate solution containing 0.838 g of palladium using a stirrer, the proportion of zirconium in all elements other than oxygen is 72 mass%, the proportion of cerium is 21 mass%, neodymium 76 g of a cerium-containing material (Daiichi Rare Element Chemical Co., Ltd.) having a ratio of 5 mass% and a lanthanum ratio of 2 mass% was added and stirred for 1 hour. This mixed solution was dried at 120 ° C. for 6 hours or more, and then calcined at 500 ° C. for 1 hour in the air. As described above, the second supported catalyst 32 was obtained in the form of powder. Hereinafter, the second supported catalyst 32 is referred to as a supported catalyst SCb1.

  Then, 61.8 g of the supported catalyst SCa1, 76.8 g of the supported catalyst SCb1, 45 g of β-type zeolite (manufactured by Tosoh Corporation), 15 g of boehmite, and 500 g of pure water were mixed. Next, using a ball mill, the average particle size of the particles in the mixed solution was adjusted to 1 to 10 μm to obtain slurry S1.

  The slurry S1 was applied to a 1.3 L honeycomb carrier that had been sufficiently dried so that the adhesion amount per liter became 190.62 g. This was baked in the air at 500 ° C. for 1 hour.

  As described above, an exhaust gas-purifying catalyst 1 was obtained. Hereinafter, the exhaust gas-purifying catalyst 1 is referred to as catalyst C1.

  In this catalyst C1, the proportion of palladium contained in the supported catalyst SCb1 in the total amount of platinum contained in the supported catalyst SCa1 and palladium contained in the supported catalyst SCb1 was 35.4% by mass.

<Manufacture of catalyst C2>
Instead of a platinum nitrate solution containing 1.531 g of platinum, a platinum nitrate solution containing 1.2 g of platinum and a palladium nitrate solution containing 0.200 g of palladium instead of a palladium nitrate solution containing 0.255 g of palladium A mixed solution MS2 was obtained by the same method as described above for the mixed solution MS1 except that and were used.

  Next, a treatment liquid L2 was obtained by the same method as described above for the treatment liquid L1 except that the mixed solution MS2 was used instead of the mixed solution MS1.

  Next, a first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the treatment liquid L2 was used instead of the treatment liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa2.

  The mass ratio of platinum to palladium in this supported catalyst SCa2 was 6.0.

  For this supported catalyst SCa2, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 77.2%.

  For this supported catalyst SCa2, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 11.4 nm.

  Next, in place of the palladium nitrate solution containing 0.838 g of palladium, a second supported catalyst was obtained in the same manner as described above for the supported catalyst SCb1 except that a palladium nitrate solution containing 1.2 g of palladium was used. Catalyst 32 was obtained. Hereinafter, the second supported catalyst 32 is referred to as SCb2.

  The slurry S1 is then described above except that 61.4 g of supported catalyst SCa2 is used instead of 61.8 g of supported catalyst SCa1 and 77.2 g of supported catalyst SCb2 is used instead of 76.8 g of supported catalyst SCb1. A slurry S2 was obtained by the same method as described above.

  Next, an exhaust gas purifying catalyst was obtained in the same manner as described above for the catalyst C1 except that the slurry S2 was used instead of the slurry S1 and the amount of adhesion per liter on the honeycomb carrier was changed from 190.62 g to 190.60 g. Got. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C2.

  In this catalyst C2, the proportion of palladium contained in the supported catalyst SCb2 in the total amount of platinum contained in the supported catalyst SCa2 and palladium contained in the supported catalyst SCb2 was 50.0% by mass.

<Manufacture of catalyst C3>
Instead of a platinum nitrate solution containing 1.531 g of platinum, a platinum nitrate solution containing 1.8 g of platinum and a palladium nitrate solution containing 0.300 g of palladium instead of a palladium nitrate solution containing 0.255 g of palladium A mixed solution MS3 was obtained in the same manner as described above for the mixed solution MS1 except that was used.

  Next, a treatment liquid L3 was obtained by the same method as described above for the treatment liquid L1 except that the mixed solution MS3 was used instead of the mixed solution MS1.

  Next, a first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the treatment liquid L3 was used instead of the treatment liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa3.

  The mass ratio of platinum to palladium in this supported catalyst SCa3 was 6.0.

  For this supported catalyst SCa3, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 78.9%.

  For this supported catalyst SCa3, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 11.1 nm.

  Next, in the same manner as described above for the supported catalyst SCb1, except that a palladium nitrate solution containing 0.5 g of palladium was used instead of the palladium nitrate solution containing 0.838 g of palladium, the second supported catalyst was used. Catalyst 32 was obtained. Hereinafter, the second supported catalyst 32 is referred to as a supported catalyst SCb3.

  The slurry S1 was then described above except that 62.1 g of supported catalyst SCa3 was used instead of 61.8 g of supported catalyst SCa1, and 76.5 g of supported catalyst SCb3 was used instead of 76.8 g of supported catalyst SCb1. A slurry S3 was obtained by the same method as described above.

  Next, an exhaust gas purifying catalyst was obtained in the same manner as described above for the catalyst C1 except that the slurry S3 was used instead of the slurry S1 and the amount of adhesion per liter on the honeycomb carrier was changed from 190.62 g to 190.60 g. Got. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C3.

  In this catalyst C3, the proportion of palladium contained in the supported catalyst SCb3 in the total amount of platinum contained in the supported catalyst SCa3 and palladium contained in the supported catalyst SCb3 was 21.7% by mass.

<Manufacture of catalyst C4>
A first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the amount of the alumina powder was changed from 60 g to 20 g. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa4.

  The mass ratio of platinum to palladium in this supported catalyst SCa4 was 6.0.

  For this supported catalyst SCa4, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 82.5%.

  For this supported catalyst SCa4, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 10.2 nm.

  Next, 76 g of a cerium-containing material having a proportion of zirconium in all elements other than oxygen of 72% by mass, a proportion of cerium of 21% by mass, a proportion of neodymium of 5% by mass and a proportion of lanthanum of 2% by mass was used. Instead, a cerium-containing material (Daiichi Rare Element Chemical Co., Ltd.) in which the proportion of aluminum in all elements other than oxygen is 51 mass%, the proportion of zirconium is 29 mass%, and the proportion of cerium is 20 mass% A second supported catalyst 32 was obtained by the same method as described above for the supported catalyst SCb1 except that 60 g was used. Hereinafter, the second supported catalyst 32 is referred to as a supported catalyst SCb4.

  Next, slurry S1 is described above except that 21.8 g of supported catalyst SCa4 instead of 61.8 g of supported catalyst SCa1 and 60.8 g of supported catalyst SCb4 instead of 76.8 g of supported catalyst SCb1 were used. A slurry S4 was obtained by the same method as described above.

  Next, the slurry S4 was used in place of the slurry S1, and the amount of deposit per liter on the honeycomb carrier was changed from 190.62 g to 134.62 g. A catalyst was obtained. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C4.

  In this catalyst C4, the proportion of palladium contained in the supported catalyst SCb4 in the total amount of platinum contained in the supported catalyst SCa4 and palladium contained in the supported catalyst SCb4 was 35.4% by mass.

<Manufacture of catalyst C5>
Instead of a platinum nitrate solution containing 1.531 g platinum, a platinum nitrate solution containing 1.28 g platinum and a palladium nitrate solution containing 0.640 g palladium instead of a palladium nitrate solution containing 0.255 g palladium. A mixed solution MS5 was obtained by the same method as described above for the mixed solution MS1 except that and were used.

  Next, the processing solution L1 is described above except that the mixed solution MS5 is used instead of the mixed solution MS1, and the TMAH aqueous solution containing 1.28 g of TMAH is used instead of the TMAH aqueous solution containing 1.53 g of TMAH. A treatment liquid L5 was obtained by the same method as described above.

  A first supported catalyst 31 was obtained in the same manner as described above for the supported catalyst SCa1, except that the process liquid L5 was used instead of the process liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa5.

  The mass ratio of platinum to palladium in this supported catalyst SCa5 was 2.0.

  For this supported catalyst SCa5, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 53.4%.

  For this supported catalyst SCa5, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 10.6 nm.

  Next, in the same manner as described above for the supported catalyst SCb1, except that a palladium nitrate solution containing 0.7 g of palladium was used instead of the palladium nitrate solution containing 0.838 g of palladium, the second supported catalyst was used. Catalyst 32 was obtained. Hereinafter, the second supported catalyst 32 is referred to as a supported catalyst SCb5.

  Next, slurry S1 is described above except that 61.9 g of supported catalyst SCa5 is used instead of 61.8 g of supported catalyst SCa1 and 76.7 g of supported catalyst SCb5 is used instead of 76.8 g of supported catalyst SCb1. A slurry S5 was obtained by the same method as described above.

  Next, an exhaust gas purification catalyst was obtained by the same method as described above for the catalyst C1 except that the slurry S5 was used instead of the slurry S1. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C5.

  In this catalyst C5, the proportion of palladium contained in the supported catalyst SCb5 in the total amount of platinum contained in the supported catalyst SCa5 and palladium contained in the supported catalyst SCb5 was 35.4% by mass.

<Manufacture of catalyst C6>
A treatment liquid L6 was obtained by the same method as described above for the treatment liquid L1 except that a TMAH aqueous solution containing 0.76 g of TMAH was used instead of the TMAH aqueous solution containing 1.53 g of TMAH.

  Next, a first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the treatment liquid L6 was used instead of the treatment liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa6.

  The mass ratio of platinum to palladium in this supported catalyst SCa6 was 6.0.

  For this supported catalyst SCa6, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 44.9%.

  For this supported catalyst SCa6, the average particle diameter of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 12.1 nm.

  Next, slurry S6 was obtained in the same manner as described above for slurry S1, except that 61.8 g of supported catalyst SCa6 was used instead of 61.8 g of supported catalyst SCa1.

  Next, an exhaust gas purification catalyst was obtained by the same method as described above for the catalyst C1 except that the slurry S6 was used instead of the slurry S1. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C6.

  In this catalyst C6, the proportion of palladium contained in the supported catalyst SCb1 in the total amount of platinum contained in the supported catalyst SCa6 and palladium contained in the supported catalyst SCb1 was 35.4% by mass.

<Manufacture of catalyst C7>
Instead of a platinum nitrate solution containing 1.531 g of platinum, a platinum nitrate solution containing 1.44 g of platinum and a palladium nitrate solution containing 0.480 g of palladium instead of a palladium nitrate solution containing 0.255 g of palladium A mixed solution MS7 was obtained by the same method as described above for the mixed solution MS1 except that and were used.

  Next, the treatment liquid L1 was described above except that the mixed solution MS7 was used instead of the mixed solution MS1, and the TMAH aqueous solution containing 1.36 g of TMAH was used instead of the TMAH aqueous solution containing 1.53 g of TMAH. A treatment liquid L7 was obtained by the same method as described above.

  A first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the treatment liquid L7 was used instead of the treatment liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa7.

  The mass ratio of platinum to palladium in this supported catalyst SCa7 was 3.0.

  For this supported catalyst SCa7, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 56.8%.

  For this supported catalyst SCa7, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 10.2 nm.

  The slurry S1 is then described above except that 61.9 g of supported catalyst SCa7 is used instead of 61.8 g of supported catalyst SCa1 and 76.7 g of supported catalyst SCb5 is used instead of 76.8 g of supported catalyst SCb1. A slurry S7 was obtained by the same method as described above.

  Next, an exhaust gas purification catalyst was obtained by the same method as described above for the catalyst C1 except that the slurry S7 was used instead of the slurry S1. Hereinafter, this exhaust gas-purifying catalyst is referred to as catalyst C7.

  In this catalyst C7, the proportion of palladium contained in the supported catalyst SCb5 in the total amount of platinum contained in the supported catalyst SCa7 and palladium contained in the supported catalyst SCb5 was 32.7% by mass.

<Manufacture of catalyst C8>
A supported catalyst SCa8 was obtained in the same manner as described above for the supported catalyst SCa1, except that the amount of alumina powder was changed from 60 g to 20 g and the calcination was performed in a nitrogen atmosphere.

  The mass ratio of platinum to palladium in this supported catalyst SCa8 was 6.0.

  For this supported catalyst SCa8, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 88.9%.

  For this supported catalyst SCa8, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 8.4 nm.

  Next, the slurry S1 is described above except that 21.8 g of the supported catalyst SCa8 is used instead of the 61.8 g of the supported catalyst SCa1, and 60.8 g of the supported catalyst SCb4 is used instead of the 76.8 g of supported catalyst SCb1. By a method similar to that described above, slurry S8 was obtained.

  Next, the slurry S8 was used instead of the slurry S1, and the exhaust gas purification was performed in the same manner as described above for the catalyst C1, except that the amount of adhesion per liter on the honeycomb carrier was changed from 190.62 g to 134.62 g. A catalyst was obtained. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C8.

  In this catalyst C8, the proportion of palladium contained in the supported catalyst SCb4 in the total amount of platinum contained in the supported catalyst SCa8 and palladium contained in the supported catalyst SCb4 was 35.4% by mass.

<Manufacture of catalyst C9>
Instead of a platinum nitrate solution containing 1.531 g platinum, a platinum nitrate solution containing 1.4288 g platinum, and a palladium nitrate solution containing 0.3572 g palladium instead of a palladium nitrate solution containing 0.255 g palladium. A mixed solution MS9 was obtained by the same method as described above for the mixed solution MS1 except that and were used.

  Next, a treatment liquid L9 was obtained by the same method as described above for the treatment liquid L1 except that the mixed solution MS9 was used instead of the mixed solution MS1.

  The supported catalyst SCa9 is treated in the same manner as described above for the supported catalyst SCa1, except that the treatment liquid L9 is used instead of the treatment liquid L1, the amount of the alumina powder is changed from 60 g to 20 g, and the calcination is performed in a nitrogen atmosphere. Got.

  The mass ratio of platinum to palladium in this supported catalyst SCa9 was 4.0.

  For this supported catalyst SCa9, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 85.5%.

  For this supported catalyst SCa9, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. However, since the particle size of platinum was small, it could not be measured. Then, the average particle diameter of platinum was calculated | required by the method mentioned above using CO pulse adsorption method. As a result, the average particle size was 7 nm.

  Next, the slurry S1 is described above except that 21.8 g of the supported catalyst SCa9 is used instead of the 61.8 g of the supported catalyst SCa1, and 60.8 g of the supported catalyst SCb4 is used instead of the 76.8 g of supported catalyst SCb1. A slurry S9 was obtained by the same method as described above.

  Next, the slurry S9 was used in place of the slurry S1, and the amount of deposit per liter on the honeycomb carrier was changed from 190.62 g to 134.62 g. A catalyst was obtained. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C9.

  In this catalyst C9, the proportion of palladium contained in the supported catalyst SCb4 in the total amount of platinum contained in the supported catalyst SCa9 and palladium contained in the supported catalyst SCb4 was 37.0% by mass.

<Manufacture of catalyst C10>
Instead of using 76 g of a cerium-containing material in which the proportion of zirconium in all elements other than oxygen is 72 mass%, the proportion of cerium is 21 mass%, the proportion of neodymium is 5 mass%, and the proportion of lanthanum is 2 mass%, 60 g of a cerium-containing material (Daiichi Rare Element Chemical Co., Ltd.) in which the proportion of aluminum in all elements other than oxygen is 51 mass%, the proportion of zirconium is 33 mass%, and the proportion of cerium is 17 mass% was used. Except for this, the second supported catalyst 32 was obtained by the same method as described above for the supported catalyst SCb1. Hereinafter, the second supported catalyst 32 is referred to as a supported catalyst SCb10.

  Next, the slurry S1 is described above except that 21.8 g of the supported catalyst SCa4 instead of 61.8 g of the supported catalyst SCa1 and 60.8 g of supported catalyst SCb10 instead of the 76.8 g of supported catalyst SCb1 were used. A slurry S10 was obtained by the same method as described above.

  Next, the slurry S10 was used instead of the slurry S1, and the exhaust gas purification was performed in the same manner as described above for the catalyst C1, except that the amount of adhesion per liter on the honeycomb carrier was changed from 190.62 g to 134.62 g. A catalyst was obtained. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C10.

  In this catalyst C10, the proportion of palladium contained in the supported catalyst SCb10 in the total amount of platinum contained in the supported catalyst SCa4 and palladium contained in the supported catalyst SCb10 was 35.4% by mass.

<Manufacture of catalyst C11>
Instead of using 76 g of a cerium-containing material in which the proportion of zirconium in all elements other than oxygen is 72 mass%, the proportion of cerium is 21 mass%, the proportion of neodymium is 5 mass%, and the proportion of lanthanum is 2 mass%, 60 g of a cerium-containing material (Daiichi Rare Element Chemical Co., Ltd.) in which the proportion of aluminum in all elements other than oxygen is 51 mass%, the proportion of zirconium is 27 mass%, and the proportion of cerium is 22 mass% was used. Except for this, the second supported catalyst 32 was obtained by the same method as described above for the supported catalyst SCb1. Hereinafter, the second supported catalyst 32 is referred to as a supported catalyst SCb11.

  Next, the slurry S1 is described above except that 21.8 g of the supported catalyst SCa4 instead of 61.8 g of the supported catalyst SCa1 and 60.8 g of supported catalyst SCb11 instead of the 76.8 g of supported catalyst SCb1 were used. A slurry S11 was obtained by the same method as described above.

  Next, the slurry S11 was used in place of the slurry S1, and the amount of deposit per liter on the honeycomb carrier was changed from 190.62 g to 134.62 g. A catalyst was obtained. Hereinafter, this exhaust gas-purifying catalyst is referred to as catalyst C11.

  In this catalyst C11, the proportion of palladium contained in the supported catalyst SCb11 in the total amount of platinum contained in the supported catalyst SCa4 and palladium contained in the supported catalyst SCb11 was 35.4% by mass.

<Manufacture of catalyst C12>
The second supported catalyst 32 was prepared in the same manner as described above for the supported catalyst SCb1, except that a palladium nitrate solution containing 0.66 g of palladium was used instead of the palladium nitrate solution containing 0.838 g of palladium. Obtained. Hereinafter, the second supported catalyst 32 is referred to as SCb12.

  Next, a slurry S12 was obtained in the same manner as described above for the slurry S1, except that 76.7 g of the supported catalyst SCb12 was used instead of the 76.8 g of the supported catalyst SCb1.

  Next, an exhaust gas purifying catalyst was obtained in the same manner as described above for the catalyst C1 except that the slurry S12 was used instead of the slurry S1 and the amount of adhesion per liter on the honeycomb carrier was changed from 190.62 g to 190.45 g. Got. Hereinafter, this exhaust gas-purifying catalyst is referred to as catalyst C12.

  In this catalyst C12, the proportion of palladium contained in the supported catalyst SCb12 in the total amount of platinum contained in the supported catalyst SCa1 and palladium contained in the supported catalyst SCb12 was 30.1% by mass.

<Manufacture of catalyst C13>
The second supported catalyst 32 was prepared in the same manner as described above for the supported catalyst SCb1 except that a palladium nitrate solution containing 1.05 g of palladium was used instead of the palladium nitrate solution containing 0.838 g of palladium. Obtained. Hereinafter, the second supported catalyst 32 is referred to as SCb13.

  Next, a slurry S13 was obtained in the same manner as described above for the slurry S1, except that 77.1 g of the supported catalyst SCb13 was used instead of the 76.8 g of the supported catalyst SCb1.

  Next, an exhaust gas purifying catalyst was obtained in the same manner as described above for the catalyst C1 except that the slurry S13 was used instead of the slurry S1 and the amount of adhesion per liter on the honeycomb carrier was changed from 190.62 g to 190.84 g. Got. Hereinafter, this exhaust gas-purifying catalyst is referred to as catalyst C13.

  In this catalyst C13, the proportion of palladium contained in the supported catalyst SCb13 in the total amount of platinum contained in the supported catalyst SCa1 and palladium contained in the supported catalyst SCb13 was 40.7% by mass.

<Manufacture of catalyst C14>
Instead of a platinum nitrate solution containing 1.531 g platinum, a platinum nitrate solution containing 1.4288 g platinum, and a palladium nitrate solution containing 0.3572 g palladium instead of a palladium nitrate solution containing 0.255 g palladium. A mixed solution MS14 was obtained by the same method as described above for the mixed solution MS1 except that and were used.

  Next, a treatment liquid L14 was obtained by the same method as described above for the treatment liquid L1 except that the mixed solution MS14 was used instead of the mixed solution MS1.

  A first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the treatment liquid L14 was used instead of the treatment liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa14.

  The mass ratio of platinum to palladium in this supported catalyst SCa14 was 4.0.

  For this supported catalyst SCa14, the alloying rate was determined by the same method as that performed for supported catalyst SCa1. As a result, the alloying rate was 82.5%.

  For this supported catalyst SCa14, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 11 nm.

  Next, slurry S14 was obtained in the same manner as described above for slurry S1 except that 61.8 g of supported catalyst SCa14 was used instead of 61.8 g of supported catalyst SCa1.

  Next, an exhaust gas purification catalyst was obtained by the same method as described above for the catalyst C1 except that the slurry S14 was used instead of the slurry S1. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C14.

  In this catalyst C14, the proportion of palladium contained in the supported catalyst SCb1 in the total amount of platinum contained in the supported catalyst SCa14 and palladium contained in the supported catalyst SCb1 was 37.0% by mass.

<Manufacture of catalyst C15>
Instead of a platinum nitrate solution containing 1.531 g platinum, a platinum nitrate solution containing 1.56 g platinum and a palladium nitrate solution containing 0.223 g palladium instead of a palladium nitrate solution containing 0.255 g palladium. A mixed solution MS15 was obtained in the same manner as described above for the mixed solution MS1 except that was used.

  Next, a treatment liquid L15 was obtained by the same method as described above for the treatment liquid L1 except that the mixed solution MS15 was used instead of the mixed solution MS1.

  A first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the treatment liquid L15 was used instead of the treatment liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa15.

  The mass ratio of platinum to palladium in this supported catalyst SCa15 was 7.0.

  For this supported catalyst SCa15, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 82.5%.

  For this supported catalyst SCa15, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 11 nm.

  Next, a slurry S15 was obtained in the same manner as described above for the slurry S1, except that 61.8 g of the supported catalyst SCa15 was used instead of 61.8 g of the supported catalyst SCa1.

  Next, an exhaust gas purification catalyst was obtained by the same method as described above for the catalyst C1 except that the slurry S15 was used instead of the slurry S1. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C15.

  In this catalyst C15, the proportion of palladium contained in the supported catalyst SCb1 in the total amount of platinum contained in the supported catalyst SCa15 and palladium contained in the supported catalyst SCb1 was 34.9% by mass.

<Manufacture of catalyst C16>
Instead of a platinum nitrate solution containing 1.531 g of platinum, a platinum nitrate solution containing 0.5 g of platinum and a palladium nitrate solution containing 0.083 g of palladium instead of a palladium nitrate solution containing 0.255 g of palladium A mixed solution MS16 was obtained by the same method as described above for the mixed solution MS1 except that and were used.

  Next, a treatment liquid L16 was obtained by the same method as described above for the treatment liquid L1 except that the mixed solution MS16 was used instead of the mixed solution MS1.

  Next, a first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the process liquid L16 was used instead of the process liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa16.

  The mass ratio of platinum to palladium in this supported catalyst SCa16 was 6.0.

  For this supported catalyst SCa16, the alloying rate was determined by the same method as that performed for supported catalyst SCa1. As a result, the alloying rate was 80.2%.

  For this supported catalyst SCa16, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 12 nm.

  Next, the second supported catalyst 32 was obtained in the same manner as described above for the supported catalyst SCb1, except that a palladium nitrate solution containing 2 g of palladium was used instead of the palladium nitrate solution containing 0.838 g of palladium. Got. Hereinafter, the second supported catalyst 32 is referred to as a supported catalyst SCb16.

  Next, the slurry S1 is described above except that 60.6 g of supported catalyst SCa16 is used instead of 61.8 g of supported catalyst SCa1 and 78.0 g of supported catalyst SCb16 is used instead of 76.8 g of supported catalyst SCb1. A slurry S16 was obtained by the same method as described above.

  Next, an exhaust gas purifying catalyst was obtained in the same manner as described above for the catalyst C1 except that the slurry S16 was used instead of the slurry S1 and the amount of adhesion per liter on the honeycomb carrier was changed from 190.62 g to 190.58 g. Got. Hereinafter, this exhaust gas-purifying catalyst is referred to as catalyst C16.

  In this catalyst C16, the proportion of palladium contained in the supported catalyst SCb16 in the total amount of platinum contained in the supported catalyst SCa16 and palladium contained in the supported catalyst SCb16 was 80.0% by mass.

<Manufacture of catalyst C17>
Instead of a platinum nitrate solution containing 1.531 g of platinum, a platinum nitrate solution containing 2.2 g of platinum and a palladium nitrate solution containing 0.367 g of palladium instead of a palladium nitrate solution containing 0.255 g of palladium A mixed solution MS17 was obtained in the same manner as described above for the mixed solution MS1 except that the above was used.

  Next, a treatment liquid L17 was obtained by the same method as described above for the treatment liquid L1 except that the mixed solution MS17 was used instead of the mixed solution MS1.

  Next, a first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the process liquid L17 was used instead of the process liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa17.

  The mass ratio of platinum to palladium in this supported catalyst SCa17 was 6.0.

  For this supported catalyst SCa17, the alloying rate was determined by the same method as that performed for supported catalyst SCa1. As a result, the alloying rate was 75.6%.

  For this supported catalyst SCa17, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 10.2 nm.

  Next, a second supported catalyst 32 was obtained by the same method as described above for the supported catalyst SCb1 except that the nitric acid solution containing palladium was omitted. Hereinafter, the second supported catalyst 32 is referred to as a supported catalyst SCb17.

  Next, the slurry S1 described above is used except that 62.6 g of the supported catalyst SCa17 is used instead of the 61.8 g of the supported catalyst SCa1, and 76.0 g of the supported catalyst SCb17 is used instead of the 76.8 g of supported catalyst SCb1. A slurry S17 was obtained by the same method as described above.

  Next, an exhaust gas purifying catalyst was obtained in the same manner as described above for the catalyst C1 except that the slurry S7 was used instead of the slurry S1 and the amount of adhesion per liter on the honeycomb carrier was changed from 190.62 g to 190.57 g. Got. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C17.

  In this catalyst C17, the proportion of palladium contained in the supported catalyst SCb17 in the total amount of platinum contained in the supported catalyst SCa17 and palladium contained in the supported catalyst SCb17 was 0% by mass.

<Manufacture of catalyst C18>
A colloidal chemical solution was obtained by mixing a platinum nitrate solution containing 1.531 g of platinum, a palladium nitrate solution containing 0.255 g of palladium, and a PVP solution containing polyvinylpyrrolidone (PVP).

  Next, this colloidal chemical solution was poured into 200 g of pure water and stirred for 5 minutes or more to prepare a treatment solution L18.

  Next, a first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the treatment liquid L18 was used instead of the treatment liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa18.

  The mass ratio of platinum to palladium in this supported catalyst SCa18 was 6.0.

  For this supported catalyst SCa18, the alloying rate was determined by the same method as that performed for supported catalyst SCa1. As a result, the alloying rate was 53.4%.

  For this supported catalyst SCa18, the average particle size of platinum was determined by the same method as that performed for supported catalyst SCa1. As a result, the average particle size was 15.1 nm.

  Next, slurry S18 was obtained by the same method as described above for slurry S1, except that 61.8 g of supported catalyst SCa18 was used instead of 61.8 g of supported catalyst SCa1.

  Next, an exhaust gas purification catalyst was obtained by the same method as described above for the catalyst C1 except that the slurry S18 was used instead of the slurry S1. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C18.

  In this catalyst C18, the proportion of palladium contained in the supported catalyst SCb1 in the total amount of platinum contained in the supported catalyst SCa18 and palladium contained in the supported catalyst SCb1 was 35.4% by mass.

<Manufacture of catalyst C19>
A treatment liquid L19 was obtained by the same method as described above for the treatment liquid L1 except that the TMAH aqueous solution was omitted.

  Next, a first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the treatment liquid L19 was used instead of the treatment liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa19.

  The mass ratio of platinum to palladium in this supported catalyst SCa19 was 6.0.

  For this supported catalyst SCa19, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 77.2%.

  For this supported catalyst SCa19, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 15.5 nm.

  Next, slurry S19 was obtained in the same manner as described above for slurry S1, except that 61.8 g of supported catalyst SCa19 was used instead of 61.8 g of supported catalyst SCa1.

  Next, an exhaust gas purification catalyst was obtained by the same method as described above for the catalyst C1 except that the slurry S19 was used instead of the slurry S1. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C19.

  In this catalyst C19, the proportion of palladium contained in the supported catalyst SCb1 in the total amount of platinum contained in the supported catalyst SCa19 and palladium contained in the supported catalyst SCb1 was 35.4% by mass.

<Manufacture of catalyst C20>
Instead of using 76 g of a cerium-containing material in which the proportion of zirconium in all elements other than oxygen is 72 mass%, the proportion of cerium is 21 mass%, the proportion of neodymium is 5 mass%, and the proportion of lanthanum is 2 mass%, 60 g of a cerium-containing material (Daiichi Rare Element Chemical Co., Ltd.) in which the proportion of aluminum in all elements other than oxygen is 51 mass%, the proportion of zirconium is 39 mass%, and the proportion of cerium is 10 mass% was used. Except for this, the second supported catalyst 32 was obtained by the same method as described above for the supported catalyst SCb1. Hereinafter, the second supported catalyst 32 is referred to as a supported catalyst SCb20.

  Next, slurry S1 is described above except that 21.8 g of supported catalyst SCa4 instead of 61.8 g of supported catalyst SCa1 and 60.8 g of supported catalyst SCb20 instead of 76.8 g of supported catalyst SCb1 were used. A slurry S20 was obtained by the same method as described above.

  Next, the slurry S20 was used in place of the slurry S1, and the exhaust gas purification was performed in the same manner as described above for the catalyst C1, except that the amount of adhesion per liter on the honeycomb carrier was changed from 190.62 g to 134.62 g. A catalyst was obtained. Hereinafter, this exhaust gas-purifying catalyst is referred to as catalyst C20.

  In this catalyst C20, the proportion of palladium contained in the supported catalyst SCb20 in the total amount of platinum contained in the supported catalyst SCa4 and palladium contained in the supported catalyst SCb20 was 35.4% by mass.

<Manufacture of catalyst C21>
Instead of a platinum nitrate solution containing 1.531 g platinum, a platinum nitrate solution containing 1.56 g platinum, and a palladium nitrate solution containing 0.195 g palladium instead of a palladium nitrate solution containing 0.255 g palladium. A mixed solution MS21 was obtained by the same method as described above for the mixed solution MS1 except that and were used.

  Next, a treatment liquid L21 was obtained by the same method as described above for the treatment liquid L1 except that the mixed solution MS21 was used instead of the mixed solution MS1.

  Next, a first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the process liquid L21 was used instead of the process liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa21.

  The mass ratio of platinum to palladium in this supported catalyst SCa21 was 8.0.

  For this supported catalyst SCa21, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 78.5%.

  For this supported catalyst SCa21, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 13.4 nm.

  Next, in the same manner as described above for the supported catalyst SCb1, except that a palladium nitrate solution containing 0.85 g of palladium was used instead of the palladium nitrate solution containing 0.838 g of palladium, the second supported catalyst was used. Catalyst 32 was obtained. Hereinafter, the second supported catalyst 32 is referred to as a supported catalyst SCb21.

  Next, the slurry S1 is described above except that 61.8 g of the supported catalyst SCa21 is used instead of 61.8 g of the supported catalyst SCa1, and 76.9 g of supported catalyst SCb21 is used instead of the 76.8 g of supported catalyst SCb1. A slurry S21 was obtained by the same method as described above.

  Next, an exhaust gas purifying catalyst was obtained in the same manner as described above for the catalyst C1 except that the slurry S21 was used instead of the slurry S1 and the amount of adhesion per liter on the honeycomb carrier was changed from 190.62 g to 190.61 g. Got. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C21.

  In this catalyst C21, the proportion of palladium contained in the supported catalyst SCb21 in the total amount of platinum contained in the supported catalyst SCa21 and palladium contained in the supported catalyst SCb21 was 35.3% by mass.

<Manufacture of catalyst C22>
Instead of a platinum nitrate solution containing 1.531 g platinum, a platinum nitrate solution containing 1.05 g platinum and a palladium nitrate solution containing 1.050 g palladium instead of a palladium nitrate solution containing 0.255 g palladium. A mixed solution MS22 was obtained in the same manner as described above for the mixed solution MS1 except that was used.

  Next, the processing solution L1 is described above except that the mixed solution MS22 is used instead of the mixed solution MS1 and the TMAH aqueous solution containing 1.05 g of TMAH is used instead of the TMAH aqueous solution containing 1.53 g of TMAH. A treatment liquid L22 was obtained by the same method as described above.

  Next, a first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the process liquid L22 was used instead of the process liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa22.

  The mass ratio of platinum to palladium in this supported catalyst SCa22 was 1.0.

  For this supported catalyst SCa22, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 41.2%.

  For this supported catalyst SCa22, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 10.8 nm.

  Next, in the same manner as described above for the supported catalyst SCb1, except that a palladium nitrate solution containing 0.55 g of palladium was used instead of the palladium nitrate solution containing 0.838 g of palladium, the second supported catalyst was Catalyst 32 was obtained. Hereinafter, the second supported catalyst 32 is referred to as a supported catalyst SCb22.

  The slurry S1 is then described above except that 62.1 g of supported catalyst SCa22 is used instead of 61.8 g of supported catalyst SCa1 and 76.6 g of supported catalyst SCb22 is used instead of 76.8 g of supported catalyst SCb1. A slurry S22 was obtained by the same method as described above.

  Next, the catalyst for exhaust gas purification was performed in the same manner as described above for the catalyst C1 except that the slurry S22 was used instead of the slurry S1 and the amount of adhesion per liter on the honeycomb carrier was changed from 190.62 g to 190.65 g. Got. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C22.

  In this catalyst C22, the proportion of palladium contained in the supported catalyst SCb22 in the total amount of platinum contained in the supported catalyst SCa22 and palladium contained in the supported catalyst SCb22 was 34.4% by mass.

<Manufacture of catalyst C23>
Instead of a platinum nitrate solution containing 1.531 g platinum, a platinum nitrate solution containing 1.28 g platinum, and a palladium nitrate solution containing 0.64 g palladium instead of a palladium nitrate solution containing 0.255 g palladium. A mixed solution MS23 was obtained by the same method as described above for the mixed solution MS1 except that and were used.

  Next, a treatment liquid L23 was obtained by the same method as described above for the treatment liquid L1 except that the mixed solution MS23 was used instead of the mixed solution MS1 and the TMAH aqueous solution was omitted.

  A first supported catalyst 31 was obtained by the same method as described above for the supported catalyst SCa1 except that the process liquid L23 was used instead of the process liquid L1. Hereinafter, the first supported catalyst 31 is referred to as a supported catalyst SCa23.

  The mass ratio of platinum to palladium in this supported catalyst SCa23 was 2.0.

  For this supported catalyst SCa23, the alloying rate was determined by the same method as that performed for the supported catalyst SCa1. As a result, the alloying rate was 15.8%.

  For this supported catalyst SCa23, the average particle size of platinum was determined by the same method as that performed for the supported catalyst SCa1. As a result, the average particle size was 23.3 nm.

  Next, the slurry S1 is described above except that 61.9 g of the supported catalyst SCa23 is used instead of 61.8 g of the supported catalyst SCa1 and 76.7 g of supported catalyst SCb5 is used instead of the 76.8 g of supported catalyst SCb1. A slurry S23 was obtained by the same method as described above.

  Next, an exhaust gas purification catalyst was obtained by the same method as described above for the catalyst C1 except that the slurry S23 was used instead of the slurry S1. Hereinafter, the exhaust gas-purifying catalyst is referred to as catalyst C23.

  In this catalyst C23, the proportion of palladium contained in the supported catalyst SCb5 in the total amount of platinum contained in the supported catalyst SCa23 and palladium contained in the supported catalyst SCb5 was 35.4% by mass.

[Cold UDC mode evaluation]
The performance of the catalysts C1 to C23 was examined by the following method.
First, each of the catalysts C1 to C23 was mounted on an automobile equipped with a diesel engine. Each vehicle was driven according to the urban driving cycle (UDC) mode, and the engine was stopped for 6 hours or more. Next, the engine was cold-started and the carbon monoxide purification rate (%) was measured. At this time, idling was not performed. The results are summarized in Tables 1 and 2.

  In the above table, among the columns below the heading “first supported catalyst”, the column labeled “Pt” describes the proportion of the mass of platinum in the mass of the first supported catalyst 31. In the column labeled “Pd”, the proportion of the mass of palladium in the mass of the first supported catalyst 31 is described. The column labeled “Pt / Pd” describes the mass ratio of platinum and palladium in the first supported catalyst 31. In the column labeled “additive”, the additive used in preparing each processing solution is described. In the column labeled “alloying rate”, the alloying rate of platinum and palladium contained in the first supported catalyst 31 is described. In the column labeled “Pt average particle diameter”, the average particle diameter of platinum contained in the first supported catalyst 31 is described.

  In the above table, among the columns below the heading “second supported catalyst”, the column labeled “Pd” describes the proportion of the mass of palladium in the mass of the second supported catalyst 32. . In the column labeled “support type”, the metal elements other than oxygen contained in the second support 321 and the mass ratio thereof are described.

  In the above table, the column labeled “X / X + Y” includes the second supported catalyst in the total amount of platinum (Y) included in the first supported catalyst and palladium (X) included in the second supported catalyst. The ratio of palladium (X) contained is described. The column labeled “CO purification rate” describes the carbon monoxide purification rate when the cold UDC mode is evaluated.

  As shown in Tables 1 and 2, the exhaust gas purifying catalysts according to the catalysts C1 to C15 show better carbon monoxide purifying performance in the low temperature range than the exhaust gas purifying catalysts according to the catalysts C16 to C23. It was.

  DESCRIPTION OF SYMBOLS 1 ... Exhaust gas purification catalyst, 2 ... Base material, 3 ... Catalyst layer, 31 ... 1st supported catalyst, 32 ... 2nd supported catalyst, 33 ... Zeolite, 311 ... 1st support | carrier, 312 ... 1st noble metal, 321 ... 1st 2 carriers, 322, second noble metal.

Claims (2)

Comprising a base material and a catalyst layer supported by the base material, the catalyst layer comprising:
A first carrier made of alumina and platinum and palladium supported on the first carrier, wherein the mass ratio of platinum to palladium is in the range of 2 to 7, and the alloying ratio of platinum and palladium is 40 %, A first supported catalyst having an average particle size of platinum of 13 nm or less;
A second supported catalyst comprising a second support composed of a cerium-containing oxide having a ratio of cerium in all elements other than oxygen of 15% by mass or more; and palladium supported on the second support;
Including mixtures with zeolites,
The exhaust gas purifying catalyst, wherein a ratio of palladium contained in the second supported catalyst in a total amount of platinum contained in the first supported catalyst and palladium contained in the second supported catalyst is in a range of 20 to 50% by mass.   The exhaust gas-purifying catalyst according to claim 1, wherein the cerium-containing oxide further contains zirconium and aluminum.