Novel TWC catalysts for gasoline engine exhaust gas treatment.

Abstract

A three-way catalyst article and its use in an exhaust system for an internal combustion engine is disclosed. The catalyst article for treating exhaust gases includes a substrate including an inlet end and an outlet end having an axial length L, a first catalyst region including a first platinum group metal (PGM) component and a first oxygen storage capacity (OSC) material, the first catalyst region including an inlet end and an outlet end having an axial length L, the first OSC material having an axial length L of at least 10 m. 2 / g, and the first OSC material has a virgin specific surface area (SSA) of 30 m between the virgin first OSC material and the aged first OSC material. 2 a first catalyst region having an SSA difference of 0.15 to 0.15 / g or less.

Description

[Technical Field]

[0001] The present invention relates to catalytic articles useful for treating exhaust gas emissions from gasoline engines. [Background technology]

[0002] In internal combustion engines, hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NO x The exhaust gas produced by the engine contains various pollutants, including CO, CO₂, CO₂, CO₂, and CO₂. Emissions control systems containing exhaust gas catalytic conversion catalysts are widely used to reduce the amount of these pollutants emitted into the atmosphere. The catalyst typically used to treat the exhaust gas of a gasoline engine is the three-way catalyst (TWC). The TWC performs three main functions: (1) oxidation of CO, (2) oxidation of unburned HC, and (3) oxidation of NO₂. x The following will be reduced:

[0003] Despite advances in TWC technology, there remains a need for improved catalytic converters for particular engine platforms that simultaneously improve performance during cold start phases, provide better light-off performance, and / or improve catalyst performance. The present invention addresses these problems, among others. Summary of the Invention

[0004] One aspect of the present disclosure is directed to a catalyst composition including a platinum group metal (PGM) component and an oxygen storage capacity (OSC) material, wherein the OSC material has a metal content of at least 10 m 2 / g, and the OSC material has a virgin specific surface area (SSA) of 30 m between virgin and aged OSC material. 2 / g or less SSA difference.

[0005] Another aspect of the present disclosure is a catalytic article for treating exhaust gases, the catalytic article comprising a substrate, a first catalyst region including an inlet end and an outlet end having an axial length L, the first catalyst region including a first platinum group metal (PGM) component and a first oxygen storage capacity (OSC) material, the first OSC material having an axial length L of at least 10 m 2 / g, and the first OSC material has a virgin specific surface area (SSA) of 30 m between the virgin first OSC material and the aged first OSC material. 2 The present invention relates to a catalyst article comprising a first catalyst region having an SSA difference of 0.1 to 0.25 μm / g or less.

[0006] The present invention also includes an exhaust system for an internal combustion engine that includes the three-way catalyst component of the present invention.

[0007] The present invention also encompasses the treatment of exhaust gases from internal combustion engines, particularly gasoline engines, which method comprises contacting the exhaust gases with the three-way catalyst component of the present invention. [Brief explanation of the drawings]

[0008] [Figure 1] 1 shows an embodiment according to the present invention containing a first catalyst region (single layer) having a length of 100% of the axial length L of the substrate. [Figure 2a] 1 shows an embodiment according to the invention in which the first catalyst region is a bottom layer and extends 100% of the axial length L, and the second catalyst region is a top layer and extends 100% of the axial length L. [Figure 2b] 2b illustrates a variation of FIG. 2a. [Figure 3a] 1 illustrates an embodiment according to the present invention in which the first catalyst region extends from the inlet end for less than 100% of the axial length L, and the second catalyst region extends from the outlet end for less than 100% of the axial length L. The total length of the second and first catalyst regions is equal to or less than the axial length L. [Figure 3b] 3b illustrates a variation of FIG. 3a. [Figure 3c]1 illustrates an embodiment according to the present invention in which the first catalyst region extends from the inlet end for less than 100% of the axial length L, and the second catalyst region extends from the outlet end for less than 100% of the axial length L. The total length of the second and first catalyst regions is greater than the axial length L. [Figure 3d] 3c illustrates a variation of FIG. [Figure 4a] 1 illustrates an embodiment according to the present invention in which a first catalyst region extends less than 100% of the axial length L from the inlet end and a second catalyst region extends less than 100% of the axial length L from the outlet end. The total length of the second and first catalyst regions is equal to or less than the axial length L. A third catalyst region extends 100% of the axial length L and overlaps the first and second catalyst regions as an upper layer. [Figure 4b] 4b illustrates a variation of FIG. 4a. [Figure 4c] 1 illustrates an embodiment according to the present invention in which the third catalyst region is the bottom layer and extends 100% of the axial length L. The first catalyst region extends less than 100% of the axial length L from the inlet end, and the second catalyst region extends less than 100% of the axial length L from the outlet end. The total length of the second and first catalyst regions is less than or equal to the axial length L. [Figure 4d] 4c illustrates a variation of FIG. [Figure 5a] 1 illustrates an embodiment according to the present invention, in which the first catalyst region extends less than 100% of the axial length L from the inlet end, and the second catalyst region extends less than 100% of the axial length L from the outlet end. The total length of the second and first catalyst regions can be less than, equal to, or greater than the axial length L. The third catalyst region extends less than 100% of the axial length L from the inlet end, and the fourth catalyst region extends less than 100% of the axial length L from the outlet end. The total length of the third and fourth catalyst regions can be less than, equal to, or greater than the axial length L. The first and second catalyst regions constitute a bottom layer, and the third and fourth catalyst regions constitute a top layer. [Figure 5b] 5b illustrates a variation of FIG. 5a. [Figure 5c] 5b illustrates a variation of FIG. 5a. [Figure 5d] 5b illustrates a variation of FIG. 5a. [Figure 6a] 1 shows an embodiment according to the invention in which a first catalyst region is a bottom layer extending 100% of the axial length L, a second catalyst region is a middle layer extending 100% of the axial length L, and a third catalyst region is a top layer extending 100% of the axial length L. [Figure 6b] 6b illustrates a variation of FIG. 6a. [Figure 6c] 6b illustrates a variation of FIG. 6a. [Figure 7a] 1 illustrates an embodiment according to the present invention in which a first catalyst region extends from the inlet end less than 100% of the axial length L, and a second catalyst region extends from the outlet end less than 100% of the axial length L. The total length of the second and first catalyst regions is greater than the axial length L. A third catalyst region extends 100% of the axial length L and overlaps the first and second catalyst regions as an upper layer. [Figure 7b] 7 illustrates a variation of FIG. 7a. [Figure 7c] 7 illustrates a variation of FIG. 7a. [Figure 7d] 7 illustrates a variation of FIG. 7a. [Figure 7e] 7 illustrates a variation of FIG. 7a. [Figure 7f] 7 illustrates a variation of FIG. 7a. [Figure 7g] 1 illustrates an embodiment according to the present invention in which a first catalyst region extends less than 100% of the axial length L from the inlet end and a second catalyst region extends less than 100% of the axial length L from the outlet end. The total length of the second and first catalyst regions can be less than, equal to, or greater than the axial length L. A third catalyst region extends less than 100% of the axial length L from the inlet end and at least partially overlaps the first and / or second catalyst regions. [Figure 7h] 7A illustrates a variation of FIG. 7g. [Figure 7i] 7A illustrates a variation of FIG. 7g. [Figure 7j]1 illustrates an embodiment according to the present invention in which a first catalyst region extends less than 100% of the axial length L from the inlet end and a second catalyst region extends less than 100% of the axial length L from the outlet end. The total length of the second and first catalyst regions can be less than, equal to, or greater than the axial length L. A third catalyst region extends less than 100% of the axial length L from the outlet end and at least partially overlaps the second and / or first catalyst regions. [Figure 7k] 7j illustrates a variation of FIG. [Figure 7l] 7j illustrates a variation of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention is directed to the catalytic treatment of combustion exhaust gases, such as those produced by gasoline and other engines, and related catalyst compositions, catalyst articles, and systems. More specifically, the present invention relates to the treatment of NO in vehicle exhaust systems. x The present invention relates to the simultaneous treatment of CO, CO, and HC. While most of the technological developments for improving the thermal durability of TWCs have focused on increasing the specific surface area (SSA) of the OSC material after thermal aging, the present inventors have surprisingly discovered that reducing the SSA difference between virgin and aged OSCs significantly impacts the improved thermal durability and resulting emissions control performance of the TWC. The present inventors have discovered that the potential performance of TWCs under light-off and OSC tests, as well as the actual performance under several emissions control tests, have been improved with the present invention. The process of the present invention also reduces catalyst costs.

[0010] One aspect of the present disclosure is directed to a catalyst composition comprising a platinum group metal (PGM) component and an oxygen storage capacity (OSC) material, wherein the OSC material has a metal content of at least 10 m 2 / g, and the OSC material has a virgin specific surface area (SSA) of 30 m between virgin and aged OSC material. 2 / g or less SSA difference.

[0011] Through the research of this invention, the inventors have discovered that by selecting and applying specific types of OSC materials to TWC catalyst compositions, these novel compositions can effectively reduce NOx emissions, particularly during vehicle testing. x It was found that the catalyst exhibited excellent catalytic properties (in terms of emission control).

[0012] The PGM component may be selected from the group consisting of platinum, palladium, rhodium, and mixtures thereof, hi some embodiments, the PGM component may be Pd, Rh, or mixtures thereof.

[0013] The OSC material may be selected from the group consisting of cerium oxide, zirconium oxide, ceria-zirconia mixed oxide, and alumina-ceria-zirconia mixed oxide. More preferably, the OSC material comprises ceria-zirconia mixed oxide. The ceria-zirconia mixed oxide may further comprise a dopant, such as lanthanum, neodymium, praseodymium, or yttrium oxide. Additionally, the OSC material may function as a support material for the PGM components.

[0014] The OSC material must be at least 15m 2 / g, at least 20m 2 / g, or at least 25m 2 The OSC material can have 55m 2 / g or less, preferably 50 or 45m 2 / g or less, 40 or 35m 2 / g or less, or 30m 2 The OSC material can have an unused SSA of 10 to 55 m / g or less. 2 / g, 20-50m 2 / g, 20-40m 2 / g, or 20-30m 2 / g of unused SSA.

[0015] The OSC material can be aged under various conditions. For example, the OSC material can be aged in an oven at 1100° C. for 4 hours. The OSC material aged under such conditions has a thermal conductivity of at least 10 m / s. 2 / g, 15m 2 / g, or 20m 2 The OSC material aged under such conditions can have an SSA of 10-40 m / g. 2 / g, 15-35m 2 / g, or 20-30m 2 The OSC material can have an SSA of 30 m / g under such conditions between virgin and aged OSC material. 2 / g or less, 25m 2 / g or less, 20m 2 / g or less, 15m 2 / g or less, 10m 2 / g or less, 5m 2 Alternatively, the OSC material can be aged under hydrothermal redox conditions at 1000° C. for 4 hours. The OSC material aged under such conditions can have an SSA difference of at least 10 m 2 / g, at least 15m 2 / g, at least 20m 2 The OSC material aged under these conditions may have an SSA of 10-40 m / g. 2 / g, 15-35m 2 / g, or 20-30m 2 The OSC material can have an SSA of 40m / g. 2 / g or less, 35m 2 / g or less, 30, 25, 20, or 15m 2 / g or less, and in certain embodiments, under such conditions, the SSA difference between virgin and aged OSC material may be 10 or 5 m / g or less. 2 / g or less.

[0016] The catalyst composition may further comprise an inorganic oxide.

[0017] The inorganic oxide is preferably an oxide of an element of Groups 2, 3, 4, 5, 13, or 14. The inorganic oxide is preferably selected from the group consisting of alumina, magnesia, silica, ceria, barium oxide, and mixed oxides or composite oxides thereof. Particularly preferred inorganic oxides are alumina, lanthanum-alumina, ceria, or magnesia / alumina composite oxides. One particularly preferred inorganic oxide is alumina or lanthanum-alumina.

[0018] The OSC material and inorganic oxide may have a weight ratio of 10:1 or less, preferably 8:1 or 5:1 or less, more preferably 4:1 or 3:1 or less, and most preferably 2:1 or less.

[0019] Alternatively, the OSC material and inorganic oxide can have a weight ratio of 10:1 to 1:10, preferably 8:1 to 1:8 or 5:1 to 1:5, more preferably 4:1 to 1:4 or 3:1 to 1:3, and most preferably 2:1 to 1:2.

[0020] The catalyst composition may further comprise an alkali or alkaline earth metal.

[0021] The alkali or alkaline earth metal is preferably barium or strontium, and mixed or composite oxides thereof. Preferably, the barium or strontium, if present, is supported in an amount of 0.1 to 15 wt. %, more preferably 3 to 10 wt. %, of barium or strontium, based on the total weight of the catalyst composition.

[0022] Preferably, the barium or strontium is present as BaCO or SrCO. Such materials can be prepared by any method known in the art, such as incipient wetness impregnation or spray drying.

[0023] As demonstrated in the examples below, the catalyst composition in this embodiment can be applied as a TWC catalyst for treating exhaust gases produced by gasoline engines.

[0024] Another aspect of the present disclosure is a catalytic article for treating exhaust gases, the catalytic article comprising a substrate, a first catalyst region including an inlet end and an outlet end having an axial length L, the first catalyst region including a first platinum group metal (PGM) component and a first oxygen storage capacity (OSC) material, the first OSC material having an axial length L of at least 10 m 2 / g, and the first OSC material has a virgin specific surface area (SSA) of 30 m between the virgin first OSC material and the aged first OSC material. 2 The present invention relates to a catalyst article comprising a first catalyst region having an SSA difference of 0.1 to 0.25 μm / g or less.

[0025] First catalytic region The first PGM may be selected from the group consisting of platinum, palladium, rhodium, and mixtures thereof, hi some embodiments, the first PGM component may be Pd, Rh, or mixtures thereof.

[0026] The first OSC material may be selected from the group consisting of cerium oxide, zirconium oxide, ceria-zirconia mixed oxide, and alumina-ceria-zirconia mixed oxide. More preferably, the first OSC material comprises a ceria-zirconia mixed oxide. The ceria-zirconia mixed oxide may further comprise a dopant, such as lanthanum, neodymium, praseodymium, or yttrium oxide. Additionally, the first OSC material may function as a support material for the first PGM component. The ceria-zirconia mixed oxide may have a weight ratio of ceria dioxide to zirconia dioxide of at least 25:75, preferably greater than 35:65, and more preferably greater than 45:55.

[0027] The first OSC material is at least 15 m 2 / g, at least 20m 2 / g, or at least 25m 2 The first OSC material may have 55m / g of virgin SSA. 2 / g or less, preferably 50 or 45m 2 / g or less, 40 or 35m 2 / g or less, or 30m 2 The first OSC material may have an unused SSA of 10 to 55 m / g or less. 2 / g, 20-50m 2 / g, 20-40m 2 / g, or 20-30m 2 / g of unused SSA.

[0028] The first OSC material can be aged under various conditions. For example, the first OSC material can be aged in an oven at 1100° C. for 4 hours. The first OSC material aged under such conditions can be aged for at least 10 minutes. 2 / g, 15m 2 / g, or 20m 2 The first OSC material aged under such conditions can have an SSA of 10 to 40 m / g. 2 / g, 15-35m 2 / g, or 20-30m 2 The first OSC material may have an SSA of 30 m / g under such conditions between the virgin OSC material and the aged first OSC material. 2 / g or less, 25m 2 / g or less, 20m 2 / g or less, 15m 2 / g or less, 10m 2 / g or less, 5m 2 Alternatively, the first OSC material can be aged under hydrothermal redox conditions at 1000° C. for 4 hours. The first OSC material aged under such conditions can have an SSA difference of at least 10 m 2 / g, at least 15m 2 / g, at least 20m 2 The first OSC material aged under such conditions may have an SSA of 10 to 40 m / g. 2 / g, 15-35m 2 / g, or 20-30m 2 The first OSC material may have an SSA of 40m / g. 2 / g or less, 35m 2 / g or less, 30, 25, 20, or 15m2 / g or less, and in certain embodiments, under such conditions, the SSA difference between the virgin first OSC material and the aged first OSC material can be 10 or 5 m / g or less. 2 / g or less.

[0029] The first catalytic region may further comprise a first inorganic oxide.

[0030] The first inorganic oxide is preferably an oxide of an element of Groups 2, 3, 4, 5, 13, and 14. The first inorganic oxide is preferably selected from the group consisting of alumina, magnesia, silica, ceria, barium oxide, and mixed oxides or composite oxides thereof. Particularly preferred is alumina, lanthanum-alumina, ceria, or magnesia / alumina composite oxide. One particularly preferred first inorganic oxide is alumina or lanthanum-alumina.

[0031] The first OSC material and the first inorganic oxide may have a weight ratio of 10:1 or less, preferably 8:1 or 5:1 or less, more preferably 4:1 or 3:1 or less, and most preferably 2:1 or less.

[0032] Alternatively, the first OSC material and the first inorganic oxide can have a weight ratio of 10:1 to 1:10, preferably 8:1 to 1:8 or 5:1 to 1:5, more preferably 4:1 to 1:4 or 3:1 to 1:3, and most preferably 2:1 to 1:2.

[0033] The first catalytic region may further comprise a first alkali or alkaline earth metal.

[0034] The first alkali metal or alkaline earth metal is preferably barium or strontium, and mixed oxides or composite oxides thereof. Preferably, the barium or strontium, if present, is supported in an amount of 0.1 to 15 wt %, more preferably 3 to 10 wt %, barium or strontium, based on the total weight of the first catalyst region.

[0035] Preferably, the barium or strontium is present as BaCO or SrCO. Such materials can be prepared by any method known in the art, such as incipient wetness impregnation or spray drying.

[0036] The first catalyst region can extend over 100 percent of the axial length L (see, e.g., FIGS. 1, 2a, 2b, and 6a-6c). In some embodiments, the first catalyst region can extend over 20-99%, 30-90%, or 40-80% of the axial length L. Alternatively, the first catalyst region can extend over 30-70 percent of the axial length L. Preferably, the first catalyst region can extend over 40-60 percent, and more preferably, 45-55 percent of the axial length L (see, e.g., FIGS. 3a-5d and 7a-7l).

[0037] The total washcoat loading of the first catalyst region was 3.5 g / in 3 Less than 3.0 g / in 3 Less than 2.5g / in 3 , or 1.5g / in 3 It could be.

[0038] Second catalytic region The catalytic article may further include a second catalytic region.

[0039] The second catalyst region may further comprise a second PGM component, a second oxygen storage capacity (OSC) material, a second alkali or alkaline earth metal component, and / or a second inorganic oxide.

[0040] The second PGM component may be selected from the group consisting of platinum, palladium, rhodium, and mixtures thereof, hi some embodiments, the second PGM component may be Pd, Rh, or mixtures thereof.

[0041] The second OSC material is preferably selected from the group consisting of cerium oxide, zirconium oxide, ceria-zirconia mixed oxide, and alumina-ceria-zirconia mixed oxide. More preferably, the second OSC material comprises ceria-zirconia mixed oxide. In addition, the second OSC material may further comprise one or more dopants such as lanthanum, neodymium, praseodymium, yttrium, etc. Furthermore, the second OSC material may function as a support material for the second PGM component. The ceria-zirconia mixed oxide may have a weight ratio of ceria dioxide to ceria dioxide of at least 50:50, preferably greater than 60:40, and more preferably greater than 70:30. Alternatively, the ceria-zirconia mixed oxide may also have a weight ratio of ceria dioxide to zirconia dioxide less than 50:50, preferably less than 40:60, and more preferably less than 30:70.

[0042] The second OSC material is at least 15 m 2 / g, at least 20m 2 / g, or at least 25m 2 The second OSC material may have 55m / g of virgin SSA. 2 / g or less, preferably 50 or 45m 2 / g or less, 40 or 35m 2 / g or less, or 30m 2 The second OSC material may have an unused SSA of 10 to 55 m / g or less. 2 / g, 20-50m 2 / g, 20-40m 2 / g, or 20-30m 2 / g of unused SSA.

[0043] The second OSC material can be aged under various conditions. For example, the second OSC material can be aged in an oven at 1100° C. for 4 hours. The second OSC material aged under such conditions can be aged for at least 10 minutes. 2 / g, 15m 2 / g, or 20m 2The second OSC material aged under such conditions can have an SSA of 10 to 40 m / g. 2 / g, 15-35m 2 / g, or 20-30m 2 The second OSC material may have an SSA of 30 m / g under such conditions between the virgin second OSC material and the aged second OSC material. 2 / g or less, 25m 2 / g or less, 20m 2 / g or less, 15m 2 / g or less, 10m 2 / g or less, 5m 2 Alternatively, the second OSC material may be aged under hydrothermal redox conditions at 1000° C. for 4 hours. The second OSC material aged under such conditions may have an SSA difference of at least 10 m 2 / g, at least 15m 2 / g, at least 20m 2 The second OSC material aged under such conditions may have an SSA of 10 to 40 m / g. 2 / g, 15-35m 2 / g, or 20-30m 2 The second OSC material may have an SSA of 40m / g. 2 / g or less, 35m 2 / g or less, 30, 25, 20, or 15m 2 / g or less, and in certain embodiments, under such conditions, the SSA difference between the virgin second OSC material and the aged second OSC material can be 10 or 5 m / g or less. 2 / g or less.

[0044] The second OSC material (eg, ceria-zirconia mixed oxide) can be 10-90 wt %, preferably 25-75 wt %, more preferably 30-60 wt %, based on the total washcoat loading of the second catalyst region.

[0045] The loading of the second OSC material in the second catalyst region is 2 g / in 3In some embodiments, the loading of the second OSC material in the second catalyst region can be less than 1.5 g / in 3 , 1.2g / in 3 , 1g / in 3 , 0.8g / in 3 , or 0.7 g / in 3 The following is the result.

[0046] The total washcoat loading of the second catalyst region was 3.5 g / in 3 Less than 3.0 g / in 3 Less than 2.0g / in 3 , or 1.0 g / in 3 It could be.

[0047] The second alkali metal or alkaline earth metal is preferably barium, strontium, or a mixed oxide or composite oxide thereof. Preferably, the barium or strontium, if present, is in an amount of 0.1 to 15 wt. % barium or strontium, more preferably 3 to 10 wt. % barium or strontium, based on the total weight of the second catalyst region.

[0048] Even more preferably, the second alkali metal or alkaline earth metal is strontium, which, when present, is preferably present in an amount of 0.1 to 15 wt %, more preferably 3 to 10 wt %, based on the total weight of the second catalyst region.

[0049] The second alkali metal or alkaline earth metal is preferably a mixed oxide or composite oxide of barium and strontium. Preferably, the mixed oxide or composite oxide of barium and strontium is present in an amount of 0.1 to 15 wt %, more preferably 3 to 10 wt %, based on the total weight of the second catalyst region. More preferably, the second alkali metal or alkaline earth metal is a composite oxide of barium and strontium.

[0050] Preferably, the barium or strontium is present as BaCO or SrCO. Such materials can be prepared by any method known in the art, such as incipient wetness impregnation or spray drying.

[0051] The second inorganic oxide is preferably an oxide of an element of Groups 2, 3, 4, 5, 13, and 14. The second inorganic oxide is preferably selected from the group consisting of alumina, magnesia, silica, ceria, barium oxide, and mixed oxides or composite oxides thereof. Particularly preferred is alumina, lanthanum-alumina, ceria, or magnesia / alumina composite oxide. One particularly preferred second inorganic oxide is alumina or lanthanum-alumina.

[0052] The second OSC material and the second inorganic oxide may have a weight ratio of 10:1 or less, preferably 8:1 or 5:1 or less, more preferably 4:1 or 3:1 or less, and most preferably 2:1 or less.

[0053] Alternatively, the second OSC material and the second inorganic oxide can have a weight ratio of 10:1 to 1:10, preferably 8:1 to 1:8 or 5:1 to 1:5, more preferably 4:1 to 1:4 or 3:1 to 1:3, and most preferably 2:1 to 1:2.

[0054] The second catalyst region can extend over 100 percent of the axial length L (see, eg, Figures 2a, 2b, and 6a-6c).

[0055] The second catalyst region can extend over 30 to 70 percent of the axial length L. Preferably, it can extend over 40 to 60 percent, more preferably 45 to 55 percent, of the axial length L, and most preferably, the total length of the second region and the first region is equal to or greater than the axial length L (see, e.g., Figures 3a-5d and 7a-7l).

[0056] The second catalyst region may overlap the first catalyst region over 0.1 to 99 percent of the axial length L (e.g., see FIGS. 3c and 3d; the first catalyst region may cover the second catalyst region, or the second catalyst region may cover the first catalyst region). Alternatively, the total length of the second catalyst region and the first catalyst region may be equal to the axial length L (e.g., see FIGS. 3a and 3b). In yet another alternative, the total length of the second catalyst region and the first catalyst region may be less than the axial length L, e.g., 95%, 90%, 80%, or 70% or less of the axial length L.

[0057] In some embodiments, the first catalytic region may be supported / deposited directly on the substrate. In certain embodiments, the second catalytic region may be supported / deposited directly on the substrate.

[0058] The third catalytic region The catalytic article may further include a third catalytic region.

[0059] The third catalyst region may further comprise a third PGM component, a third oxygen storage capacity (OSC) material, a third alkali or alkaline earth metal component, and / or a third inorganic oxide.

[0060] The third PGM component may be selected from the group consisting of platinum, palladium, rhodium, and mixtures thereof, hi some embodiments, the third PGM component may be Pd, Rh, or mixtures thereof.

[0061] The third OSC material is preferably selected from the group consisting of cerium oxide, zirconium oxide, ceria-zirconia mixed oxide, and alumina-ceria-zirconia mixed oxide. More preferably, the third OSC material comprises ceria-zirconia mixed oxide. In addition, the third OSC material may further comprise one or more dopants such as lanthanum, neodymium, praseodymium, yttrium, etc. Furthermore, the third OSC material may function as a support material for the third PGM component. The ceria-zirconia mixed oxide may have a weight ratio of zirconia dioxide to ceria dioxide of at least 50:50, preferably greater than 60:40, and more preferably greater than 75:25. Alternatively, the ceria-zirconia mixed oxide may also have a weight ratio of ceria dioxide to zirconia dioxide less than 50:50, preferably less than 40:60, and more preferably less than 25:75.

[0062] The third OSC material is at least 15 m 2 / g, at least 20m 2 / g, or at least 25m 2 The third OSC material may have 55m / g of virgin SSA. 2 / g, preferably 50 or 45 m 2 / g or less, 40 or 35m 2 / g or less, or 30m 2 The third OSC material may have an unused SSA of 10 to 55 m / g or less. 2 / g, 20-50m 2 / g, 20-40m 2 / g, or 20-30m 2 / g of unused SSA.

[0063] The third OSC material can be aged under various conditions. For example, the third OSC material can be aged in an oven at 1100° C. for 4 hours. The third OSC material aged under such conditions can be aged for at least 10 minutes. 2 / g, 15m 2 / g, or 20m 2The third OSC material aged under such conditions may have an SSA of 10 to 40 m / g. 2 / g, 15-35m 2 / g, or 20-30m 2 The third OSC material may have an SSA of 30 m / g under such conditions between the virgin third OSC material and the aged third OSC material. 2 / g or less, 25m 2 / g or less, 20m 2 / g or less, 15m 2 / g or less, 10m 2 / g or less, 5m 2 Alternatively, the third OSC material may be aged under hydrothermal redox conditions at 1000° C. for 4 hours. The third OSC material aged under such conditions may have an SSA difference of at least 10 m 2 / g, at least 15m 2 / g, at least 20m 2 The third OSC material aged under such conditions may have an SSA of 10 to 40 m / g. 2 / g, 15-35m 2 / g, or 20-30m 2 The third OSC material may have an SSA of 40m / g. 2 / g or less, 35m 2 / g or less, 30, 25, 20, or 15m 2 / g or less, and in certain embodiments, under such conditions, the SSA difference between the virgin and aged third OSC material can be 10 or 5 m / g or less. 2 / g or less.

[0064] The third OSC material (eg, ceria-zirconia mixed oxide) can be 10-90 wt %, preferably 25-75 wt %, more preferably 30-60 wt %, based on the total washcoat loading of the third catalyst region.

[0065] The loading of the third OSC material in the third catalyst region is 1.5 g / in 3In some embodiments, the loading of the third OSC material in the second catalyst region can be less than 1.2 g / in 3 , 1.0g / in 3 , 0.9g / in 3 , 0.8g / in 3 , or 0.7 g / in 3 The following is the result.

[0066] The total washcoat loading of the third catalyst region was 3.5 g / in 3 Less than 3.0 g / in 3 Less than 2.5g / in 3 , or 1.5g / in 3 It could be.

[0067] The third alkali or alkaline earth metal is preferably barium, strontium, a mixed oxide or composite oxide thereof, and preferably, when present, the barium or strontium is in an amount of 0.1 to 15 wt %, more preferably 3 to 10 wt %, barium or strontium, based on the total weight of the third catalytic region.

[0068] Even more preferably, the third alkali or alkaline earth metal is strontium, which, when present, is preferably present in an amount of 0.1 to 15 wt %, more preferably 3 to 10 wt %, based on the total weight of the third catalyst region.

[0069] The third alkali or alkaline earth metal is preferably a mixed oxide or composite oxide of barium and strontium. Preferably, the mixed oxide or composite oxide of barium and strontium is present in an amount of 0.1 to 15 wt %, more preferably 3 to 10 wt %, based on the total weight of the third catalyst region. More preferably, the third alkali or alkaline earth metal is a composite oxide of barium and strontium.

[0070] Preferably, the barium or strontium is present as BaCO or SrCO. Such materials can be prepared by any method known in the art, such as incipient wetness impregnation or spray drying.

[0071] The third inorganic oxide is preferably an oxide of an element of Groups 2, 3, 4, 5, 13, and 14. The third inorganic oxide is preferably selected from the group consisting of alumina, magnesia, silica, ceria, barium oxide, and mixed oxides or composite oxides thereof. Particularly preferred is alumina, lanthanum-alumina, ceria, or magnesia / alumina composite oxide. One particularly preferred third inorganic oxide is alumina or lanthanum-alumina.

[0072] The third OSC material and the third inorganic oxide can have a weight ratio of 10:1 or less, preferably 8:1 or 5:1 or less, more preferably 4:1 or 3:1 or less, and most preferably 2:1 or less.

[0073] Alternatively, the third OSC material and the third inorganic oxide can have a weight ratio of 10:1 to 1:10, preferably 8:1 to 1:8 or 5:1 to 1:5, more preferably 4:1 to 1:4 or 3:1 to 1:3, and most preferably 2:1 to 1:2.

[0074] The third catalyst region can extend over 100 percent of the axial length L (see, eg, Figures 4a-4d and 6a-6c).

[0075] The third catalytic region can be less than the axial length L, for example, 95%, 90%, 80%, or 70% or less of the axial length L (see, for example, Figures 5a-5d and 7g-7l).

[0076] The second catalyst region may overlap the first catalyst region over 0.1 to 99 percent of the axial length L (see, e.g., Figures 7a-7l), the first catalyst region may be stacked on the second catalyst region, or the second catalyst region may be stacked on the first catalyst region). Alternatively, either the second or first region may extend over 30 to 70 percent of the axial length L. Preferably, it may extend over 40 to 60 percent, more preferably 45 to 55 percent, of the axial length L, and most preferably, the total length of the second and first regions is equal to or less than the axial length L (see, e.g., Figures 4a-4d).

[0077] The fourth catalytic region The catalytic article may further include a fourth catalytic region.

[0078] The fourth catalyst region may further comprise a fourth PGM component, a fourth oxygen storage capacity (OSC) material, a fourth alkali or alkaline earth metal component, and / or a fourth inorganic oxide.

[0079] The fourth PGM component may be selected from the group consisting of platinum, palladium, rhodium, and mixtures thereof, hi some embodiments, the fourth PGM component may be Pd, Rh, or mixtures thereof.

[0080] The fourth catalytic region may have the same or similar composition as the third catalytic region.

[0081] The fourth catalytic region may be less than the axial length L, for example, 95%, 90%, 80%, or 70% or less of the axial length L.

[0082] Alternatively, either the fourth or third catalyst region can extend over 30 to 70 percent of the axial length L. Preferably, it can extend over 40 to 60 percent, more preferably 45 to 55 percent, of the axial length L, and most preferably, the total length of the fourth and third catalyst regions is equal to or greater than the axial length L (see, e.g., Figures 5a-5d).

[0083] The catalyst article of the present invention may contain additional components known to those skilled in the art. For example, the composition of the present invention may further comprise at least one binder and / or at least one surfactant. When a binder is present, a dispersible alumina binder is preferred.

[0084] Base material Preferably, the substrate is a flow-through monolith.

[0085] The flow-through monolith substrate has a first surface and a second surface defining a longitudinal direction therebetween. The flow-through monolith substrate has a plurality of channels extending between the first surface and the second surface. The plurality of channels extend longitudinally and provide a plurality of interior surfaces (e.g., wall surfaces defining each channel). Each of the plurality of channels has an opening in the first surface and an opening in the second surface. For the avoidance of doubt, a flow-through monolith substrate is not a wall-flow filter.

[0086] The first surface is typically at the inlet end of the substrate and the second surface is at the outlet end of the substrate.

[0087] The channels may be of constant width, and each of the plurality of channels may have a uniform channel width.

[0088] Preferably, in a plane perpendicular to the longitudinal direction, the monolith substrate has 300 to 900 channels per square inch, preferably 400 to 800 channels per square inch. For example, on the first face, the density of open first channels and closed second channels is 600 to 700 channels per square inch. The channels may have cross sections that are rectangular, square, circular, oval, triangular, hexagonal, or other polygonal shapes.

[0089] The monolith substrate acts as a support to hold the catalytic material. Suitable materials for forming the monolith substrate include ceramic-like materials such as cordierite, silicon carbide, silicon nitride, zirconia, mullite, spodumene, alumina-silica magnesia, or zirconium silicate, or porous refractory metals. Such materials and their use in the manufacture of porous monolith substrates are well known in the art.

[0090] It should be noted that the flow-through monolith substrates described herein are unitary components (i.e., a single brick). Nevertheless, when forming an effluent treatment system, the substrates used may be formed by bonding together multiple channels, or may be formed by bonding together multiple smaller substrates as described herein. Such techniques, along with suitable casings and configurations for effluent treatment systems, are known in the art.

[0091] In embodiments in which the catalyst article of the present invention comprises a ceramic substrate, the ceramic substrate may be made of any suitable refractory material, such as alumina, silica, ceria, zirconia, magnesia, zeolites, silicon nitride, silicon carbide, zirconium silicate, magnesium silicate, aluminosilicates and metalloaluminosilicates (such as cordierite and spodumene), or mixtures or mixed oxides of any two or more thereof. Cordierite, magnesium aluminosilicate, and silicon carbide are particularly preferred.

[0092] In embodiments in which the catalytic article of the present invention comprises a metal substrate, the metal substrate may be made of any suitable metal, particularly heat-resistant metals and metal alloys such as titanium and stainless steel, and ferritic alloys containing iron, nickel, chromium, and / or aluminum in addition to other trace metals.

[0093] Another aspect of the present disclosure is a method for producing NOx using the catalytic articles described herein. xThe present invention is directed to a method for treating vehicle exhaust gases containing toluene, toluene, toluene diluents, toluene ether, toluene distillates, toluene nitrate, toluene tungsten, toluene tungsten, toluene distillates ...

[0094] Another aspect of the present disclosure is directed to a system for treating vehicle exhaust gases that includes a catalytic article as described herein along with a conduit for transporting exhaust gases through the system.

[0095] definition "Hydrothermal aging" is a method to reproduce the deterioration state of catalysts used in actual applications. The sample was placed in an electric furnace into which a mixture of steam and alternating reducing / oxidizing gases shown in Table 1 was introduced.

[0096] [Table 1]

[0097] As used herein, the term "region" refers to a location on a substrate that is typically obtained by drying and / or firing a washcoat. A "region" may be disposed or carried on the substrate as, for example, a "layer" or a "zone." The location or placement on the substrate is generally controlled during the process of applying the washcoat to the substrate. A "region" typically has a distinct boundary or edge (i.e., it is possible to distinguish one region from another using conventional analytical techniques).

[0098] Typically, a "region" has a substantially uniform length. Reference to a "substantially uniform length" in this context refers to a length that does not deviate more than 10% from its average value (e.g., the difference between the maximum and minimum length), preferably a length that does not deviate more than 5% from its average value, and more preferably a length that does not deviate more than 1% from its average value.

[0099] Preferably, each "region" has a substantially uniform composition (i.e., there is no substantial difference in the composition of the washcoat when comparing one portion of the region to another portion of the region). Substantially uniform composition in this context refers to a material (e.g., region) that has a composition difference of 5% or less, usually 2.5% or less, and most usually 1% or less when comparing one portion of the region to another portion of the region.

[0100] As used herein, the term "zone" refers to a region having a length less than the entire length of the substrate, such as a length of 75% or less of the entire length of the substrate. A "zone" typically has a length of at least 5% (e.g., 5% or more) of the entire length of the substrate (i.e., a substantially uniform length).

[0101] The overall length of a substrate is the distance between its inlet end and its outlet end (eg, both ends of the substrate).

[0102] As used herein, any reference to a "zone disposed at the inlet end of the substrate" refers to a zone disposed on or carried by a substrate that is closer to the inlet end of the substrate than to the outlet end of the substrate. Thus, the midpoint of the zone (i.e., a point at half its length) is closer to the inlet end of the substrate than to the outlet end of the substrate. Similarly, as used herein, any reference to a "zone disposed at the outlet end of the substrate" refers to a zone disposed on or carried by a substrate that is closer to the outlet end of the substrate than to the inlet end of the substrate. Thus, the midpoint of the zone (i.e., a point at half its length) is closer to the outlet end of the substrate than to the inlet end of the substrate.

[0103] In general, when the substrate is a wall-flow filter, any reference to "a zone disposed at the inlet end of the substrate" refers to a zone disposed on or carried by the substrate, (a) a zone that is closer to the inlet end (e.g., open end) of an inlet channel of a substrate than to the closed end (e.g., blocked or plugged end) of the inlet channel; and / or (b) Refers to a zone that is closer to the closed end (e.g., blocked or plugged end) of an outlet channel of a substrate than to the outlet end (e.g., open end) of the outlet channel.

[0104] Thus, the midpoint of the zone (i.e., the point at half its length) is (a) closer to the inlet end of the inlet channel of the substrate than to the closed end of the inlet channel, and / or (b) closer to the closed end of the outlet channel of the substrate than to the outlet end of the outlet channel.

[0105] Similarly, if the substrate is a wall-flow filter, any reference to "a zone disposed at the outlet end of the substrate" refers to a zone disposed on or carried by the substrate, (a) a zone that is closer to the outlet end (e.g., open end) of the outlet channel of the substrate than to the closed end (e.g., blocked or plugged end) of the outlet channel; and / or (b) Refers to a zone that is closer to the closed end (e.g., blocked or plugged end) of an inlet channel of a substrate than to the inlet end (e.g., open end) of the inlet channel.

[0106] Thus, the midpoint of the zone (i.e., the point at half its length) is (a) closer to the outlet end of the outlet channel of the substrate than to the closed end of the outlet channel, and / or (b) closer to the closed end of the inlet channel of the substrate than to the inlet end of the inlet channel.

[0107] If the washcoat is present on the wall of a wall-flow filter (ie, the zone is intra-wall), the zone may satisfy both (a) and (b).

[0108] The term "washcoat" is known in the art and typically refers to an adherent coating applied to a substrate during the preparation of a catalyst.

[0109] As used herein, the acronym "PGM" refers to "platinum group metals." The term "platinum group metals" generally refers to metals selected from the group consisting of Ru, Rh, Pd, Os, Ir, and Pt, preferably metals selected from the group consisting of Ru, Rh, Pd, Ir, and Pt. Generally, the term "PGM" preferably refers to metals selected from the group consisting of Rh, Pt, and Pd.

[0110] As used herein, the term "mixed oxide" generally refers to a mixture of oxides in a single phase, as conventionally known in the art. As used herein, the term "complex oxide" generally refers to a composition of oxides having two or more phases, as conventionally known in the art.

[0111] As used herein, the phrase "consisting essentially of" limits the scope of a feature to include the specified materials or steps and any other materials or steps, including, for example, trace impurities, and that do not substantially affect the basic properties of the feature. The phrase "consisting essentially of" encompasses the phrase "consisting of."

[0112] As used herein with respect to a material, the term "substantially free" typically means that the material is present in small amounts, e.g., 5% by weight or less, preferably 2% by weight or less, and more preferably 1% by weight or less, relative to the contents of a region, layer, or zone. The term "substantially free" encompasses the term "free."

[0113] As used herein with respect to a material, the term "essentially free" typically means that the material is present in trace amounts, e.g., 1% by weight or less, preferably 0.5% by weight or less, more preferably 0.1% by weight or less, in relation to the contents of a region, layer, or zone. The term "essentially free" encompasses the term "free."

[0114] As used herein, any reference to an amount, particularly a total amount, of dopant expressed as a weight percent refers to the weight of the support material or refractory metal oxide thereof.

[0115] As used herein, the term "loading" refers to g / ft on a metal weight basis. 3 Refers to a measurement in units of .

[0116] The following examples are merely illustrative of the present invention, and those skilled in the art will recognize many variations that are within the spirit and scope of the claims. [Example]

[0117] Catalysts 1 to 4 Four catalyst samples (Table 3) were prepared by the incipient wetness impregnation method, where each of the OSC1 and OSC2 materials (Table 2) in powder form was impregnated with Pd nitrate or Rh nitrate solutions at a target loading of 1% Pd or 0.2% Rh, respectively, then dried at 90°C and calcined at 500°C for 1 hour.

[0118] [Table 2]

[0119] [Table 3]

[0120] Example 1 - Conversion during pressurized OSC test The pressurized OSC time was recorded when lambda was perturbed from rich (0.94) to lean (1.03) on a powder sample (0.4 g) at a mixed gas flow rate of 5 L / min. NO conversion was calculated through feed gas online analysis when the sample was tested under rich (0.94) or lean (1.03) conditions at 500 °C. The pressurized OSC and NO conversion results are shown in Table 4 below. OSC2 consistently exhibited high OSC as a support for Pd or Rh (Catalysts 2 and 4). The lean / rich NO conversion was clearly improved when Pd or Rh was supported by OSC2, indicating that lean / rich NO conversion was highly correlated with the pressurized OSC.

[0121] [Table 4]

[0122] [Table 5]

[0123] Catalyst A: First catalytic region: The first catalytic region consisted of a first CeZr mixed oxide, La-stabilized alumina, and Pd supported on a washcoat of OSC3 (Table 5) as a Ba promoter. The washcoat loading for the first catalytic region was approximately 2.5 g / in. 3 The Pd loading is 50 g / ft 3 It was.

[0124] This washcoat was then coated onto a ceramic substrate (400 cpsi, 3.5 mil wall thickness) from the inlet face using standard coating procedures with a target coating depth of 100% of the substrate length and dried at 90°C.

[0125] Second catalytic region: The second catalytic region consisted of a second CeZr mixed oxide, La-stabilized alumina, and Rh supported on a Ba-promoter washcoat. The washcoat loading for the second catalytic region was about 1.0 g / in. 3 The Rh loading is 5g / ft 3 It was.

[0126] This second washcoat was then coated onto the outlet face of the ceramic substrate containing the first catalyst region using standard coating procedures, with a target coating depth of 100% of the substrate's length, dried at 90°C, and calcined at 500°C for 45 minutes.

[0127] Comparative catalyst B: Comparative Catalyst B is prepared by the same procedure as Catalyst A, except that in the first catalyst zone, OSC4 (Table 5) was used.

[0128] Example 2: Vehicle Test Procedures and Results Catalyst A and Comparative Catalyst B were bench aged for 150 hours at a peak temperature of 950°C using a fuel cut aging cycle, and vehicle emissions were measured in a commercial vehicle with a 1.5 liter engine using an FTP drive cycle. Emissions were measured before and after the catalyst.

[0129] [Table 6]

[0130] The tailpipe bag data are shown in Table 6. Inventive Catalyst A reduced THC, CO, and NO compared to Comparative Catalyst B. x present lower emissions (17%, 16%, and 39% reductions, respectively).

[0131] Example 3: Light-off performance test in engine test Catalyst A and Comparative Catalyst B were tested separately in a gasoline engine. Light-off performance was evaluated under typical conditions of an exhaust flow rate of 81,200 L / min, a temperature gradient of 30°C / min, and an air-fuel ratio (AFR) lambda of 14.45. THC, CO, and NO x The conversion was calculated by comparing the concentration of the feed gas and the gas concentration at the catalyst outlet. Prior to the engine light-off test, Catalyst A and Comparative Catalyst B were bench aged at a peak temperature of 950°C for 150 hours in a fuel cut aging cycle.

[0132] HC, CO, and NO for Catalyst A and Comparative Catalyst B x T 50 The light-off temperatures are shown in Table 7. The data surprisingly show that the inventive catalyst A had a T 50 (T 50 is the temperature at which 50% conversion is reached), resulting in significantly improved light-off performance.

[0133] [Table 7]

[0134] Catalyst C: First catalytic region: The first catalytic zone consisted of Pd supported on a washcoat of OSC2 (Table 2), La-stabilized alumina, and Ba-promoter. The washcoat loading of the first catalytic zone was approximately 2.0 g / in. 3 The Pd loading was 77 g / ft 3 It was.

[0135] This washcoat was then coated onto a ceramic substrate (750 cpsi, 2.5 mil wall thickness) from the inlet face using standard coating procedures with a target coating depth of 80% of the substrate length and dried at 90°C.

[0136] Second catalytic region: The second catalytic region consisted of a second CeZr mixed oxide, Rh supported on a washcoat of La-stabilized alumina. The washcoat loading for the second catalytic region was approximately 1.3 g / in. 3 The Rh loading is 8g / ft 3 It was.

[0137] This second washcoat was then coated onto the outlet face of the ceramic substrate containing the first catalyst region using standard coating procedures with a target coating depth of 80% of the substrate's length, dried at 90°C, and calcined at 500°C for 45 minutes.

[0138] Comparison catalyst D: Comparative Catalyst D is prepared by the same procedure as Catalyst C, except that in the first catalyst zone, OSC1 (Table 2) was used.

[0139] Example 4: Vehicle Test Procedures and Results Bench-aged samples of Catalyst C and Comparative Catalyst D were tested in a 2.0-liter engine vehicle using the Worldwide Light Duty Testing Procedure (WLTP). Bench aging was performed in the same 6.1-liter engine with a 150-hour operation, four-mode aging cycle, and a peak catalyst bed temperature of approximately 980°C. Vehicle exhaust dilution bag data results for unused bench-aged parts are shown in Table 8. Catalyst C of the present invention exhibited significantly lower NO emissions compared to Comparative Catalyst D. x Exhibits excellent activity for emission control (e.g., NO emissions with approximately 60% improvement over the virgin portion and 28% improvement over the aged portion) x See performance.)

[0140] [Table 8]

[0141] [Table 9]

[0142] Catalyst E: First catalytic region: The first catalytic zone consisted of Pd supported on a washcoat of OSC5 (Table 9), La-stabilized alumina, and Ba-promoter. The washcoat loading of the first catalytic zone was approximately 2.7 g / in. 3 The Pd loading was 83 g / ft 3 It was.

[0143] This washcoat was then coated onto a ceramic substrate (750 cpsi, 2.5 mil wall thickness) from the inlet face using standard coating procedures with a target coating depth of 100% of the substrate length and dried at 90°C.

[0144] Second catalytic region: The second catalytic region consisted of a second CeZr mixed oxide, La-stabilized alumina, and Rh supported on a Ba-promoter washcoat. The washcoat loading for the second catalytic region was approximately 1.4 g / in. 3 The Rh loading is 5g / ft 3 It was.

[0145] This second washcoat was then coated onto the outlet face of the ceramic substrate containing the first catalyst region using standard coating procedures, with a target coating depth of 100% of the substrate's length, dried at 90°C, and calcined at 500°C for 45 minutes.

[0146] Comparison catalyst F: Comparative Catalyst F is prepared by the same procedure as Catalyst E, except that OSC1 was used in the first catalyst zone.

[0147] Example 5: Vehicle Test Procedures and Results Catalyst E and Comparative Catalyst F were compared for their performance in treating exhaust gases from a gasoline engine as System E and Comparative System F. In either system, the exhaust system consisted of two separate catalyst bricks. Catalyst E or Comparative Catalyst F was placed in the upstream location, while the conventional catalyst was placed in the downstream location.

[0148] The catalyst systems (System E and Comparative System F) were subjected to accelerated aging to the equivalent of 150,000 miles. After aging, the catalyst articles were tested according to the Federal Test Procedure (FTP) using a 2014MY 2.0L GTDI passenger car. NO emissions from the downstream brick were measured. x , non-methane hydrocarbons (NMHCs), and CO levels were measured during the treatment process.

[0149] [Table 10]

[0150] As shown in Table 10, System E achieved almost 50% tailpipe NMHC+NO x emissions, and tailpipe CO emissions that are 75% lower than those of the comparison system F.

[0151] [Table 11]

[0152] Catalyst G: First catalytic region: The first catalytic region consisted of Pd supported on a washcoat of OSC2, La-stabilized alumina, and Ba-promoter. The washcoat loading of the first catalytic region was approximately 2.0 g / in. 3 The Pd loading is 85g / ft 3 It was.

[0153] This washcoat was then coated onto a ceramic substrate (750 cpsi, 2.5 mil wall thickness) from the inlet face using standard coating procedures with a target coating depth of 50% of the substrate length and dried at 90°C.

[0154] Second catalytic region: The second catalytic region consisted of Pd supported on a washcoat of OSC2 mixed oxide, La-stabilized alumina, and Ba-promoter. The washcoat loading of the second catalytic region was approximately 2.0 g / in. 3 The Pd loading is 6 g / ft 3 It was.

[0155] This second washcoat was then coated onto the outlet face of the ceramic substrate containing the first catalyst region using standard coating procedures, with a target coating depth of 50% of the substrate's length, dried at 90°C, and calcined at 500°C for 45 minutes.

[0156] Third catalytic region: The third catalytic region consisted of a third CeZr mixed oxide and Rh supported on a washcoat of La-stabilized alumina. The washcoat loading of the third catalytic region was about 1.5 g / in. 3 The Rh loading is 9 g / ft 3 It was.

[0157] A third washcoat was then coated from the outlet face of the ceramic substrate containing the first and second catalyst regions using standard coating procedures with a target coating depth of 100% of the substrate length, dried at 90°C, and calcined at 500°C for 45 minutes.

[0158] Comparative catalyst H: Comparative Catalyst H is prepared by the same procedure as Catalyst G, except that OSC6 (Table 11) is used in the first and second catalyst zones.

[0159] Example 6: Vehicle Test Procedures and Results Bench-aged samples of Catalyst G and Comparative Catalyst H were tested in a 2.0-liter engine vehicle using the World Wide Harmonized Exhaust Emissions and Fuel Economy Test Procedure (WLTP). Bench aging was performed in the same 6.1-liter engine with a 200-hour run, four-mode aging cycle, with a catalyst peak bed temperature of approximately 980°C. Vehicle exhaust dilution bag data results are shown in Table 12. Catalyst G of the present invention exhibits superior NOx performance compared to Comparative Catalyst H (e.g., approximately 18% improvement in NOx over the aged section). x (See Improved Performance).

[0160] [Table 12]

Claims

1. A catalyst composition for treating exhaust gases, comprising a platinum group metal (PGM) component and an oxygen storage capacity (OSC) material, wherein the OSC material is 20 to 50 m ２ / g, and the OSC material has a virgin specific surface area (SSA) of 30 m between the virgin OSC material and the OSC material aged under conditions of 1100°C for 4 hours. ２ / g or less, the OSC material comprises a ceria-zirconia mixed oxide, and the aged OSC material has an SSA difference of at least 20 m ２ / g of SSA.

2. 10. The catalyst composition of claim 1, wherein the PGM component is selected from the group consisting of platinum, palladium, rhodium, and mixtures thereof.

3. 1. A catalytic article for treating exhaust gases, comprising: a substrate including an inlet end and an outlet end having an axial length L; a first catalyst region comprising a first platinum group metal (PGM) component and a first oxygen storage capacity (OSC) material, the first OSC material having a thickness of 20 to 50 m ２ / g, and the first OSC material has a virgin specific surface area (SSA) of 30 m between the virgin first OSC material and the first OSC material aged under hydrothermal redox conditions at 1000°C for 4 hours. ２ a first catalyst region having an SSA difference of 0.1 / g or less; The OSC material comprises a ceria-zirconia mixed oxide, and the aged first OSC material has a thickness of at least 20 m. ２ / g of SSA.

4. 4. The catalytic article of claim 3, wherein the first PGM component is selected from the group consisting of platinum, palladium, rhodium, and mixtures thereof.

5. 5. The catalytic article of claim 3 or 4, further comprising a second catalytic region.

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