A novel three-zone, two-layer TWC catalyst for gasoline exhaust applications

Abstract

To provide a catalyst converter improved for a sure engine plat form, which gives high conversion efficiency and low back pressure simultaneously.SOLUTION: A catalyst article for treating exhaust gas includes: a substrate comprising an inlet end and an outlet end having an axial length L; an inlet catalyst layer starting at the inlet end and extending over 60 to 90% of the axial direction length L, the inlet catalyst layer comprising an inlet palladium component; and an outlet catalyst layer starting at the outlet end and extending over 60 to 90% of the axial direction length L, the outlet catalyst layer comprising an outlet rhodium component and overlapping the inlet catalyst layer.SELECTED DRAWING: Figure 1

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 (HCs), carbon monoxide (CO), and nitrogen oxides (NO x The exhaust gases produced by engines contain a variety of pollutants, such as CO, CO₂, CO₂, and CO₂. Emissions control systems, including exhaust gas catalysts, are widely used to reduce the amount of these pollutants emitted into the atmosphere. The catalyst typically used in gasoline engine applications is the TWC. The TWC performs three main functions: (1) oxidation of CO, (2) oxidation of unburned HC, and (3) oxidation of NO₂. x is reduced to N2.

[0003] In most catalytic converters, TWCs are coated on high-surface-area substrates that can withstand high temperatures, such as flow-through honeycomb monoliths. While the large surface area of ​​these substrates promotes the desired heterogeneous reaction, it can also contribute to increased exhaust backpressure, i.e., restricting the flow of exhaust gas from the engine to the tailpipe. High backpressure in the exhaust system can reduce engine fuel economy and power output. Despite advances in TWC technology, such as those described in U.S. Pat. Nos. 6,022,825, 9,352,279, 9,040,003, and U.S. Patent Application Publication No. 2016 / 0228818, there remains a need for improved catalytic converters for certain engine platforms that simultaneously provide high conversion rates and low backpressure. The present invention addresses these issues, among others. Summary of the Invention

[0004] One aspect of the present disclosure is directed to a catalyst article for treating exhaust gases, the catalyst article comprising: a substrate including an inlet end and an outlet end having an axial length L; an inlet catalyst layer beginning at the inlet end and extending to an axial length of less than L, the inlet catalyst layer comprising an inlet palladium component; and an outlet catalyst layer beginning at the outlet end and extending to an axial length of less than L, the outlet catalyst layer comprising an outlet rhodium component; wherein the outlet catalyst layer overlaps the inlet catalyst layer.

[0005] The present invention also includes an exhaust system for an internal combustion engine that includes the three-way catalyst component of the present invention.

[0006] 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]

[0007] [Figure 1] 1 shows a catalyst article having an inlet catalyst layer and an outlet catalyst layer, where the inlet catalyst layer is completely supported / deposited directly on a substrate, and the outlet catalyst layer is partially supported / deposited directly on a substrate and partially supported / deposited on top of the inlet catalyst layer. [Figure 2] 1 shows a catalyst article having an inlet catalyst layer and an outlet catalyst layer, the outlet catalyst layer being fully supported / deposited directly on a substrate, and the inlet catalyst layer being partially supported / deposited directly on a substrate and partially supported / deposited on top of the outlet catalyst layer. [Figure 3] 1 shows a comparative commercial catalyst article having two layers on a substrate with one zone. Detailed Description of the Invention

[0008] The present invention relates to the catalytic conversion of combustion exhaust gases, such as those produced by gasoline and other engines, and related catalyst articles and systems. More particularly, the present invention relates to the catalytic conversion of NO in vehicle exhaust systems. x The present inventors have demonstrated a method for simultaneously treating NO, CO, and HC while simultaneously generating low back pressure.x We have discovered a synergistic relationship between certain catalytically active metals and their orientation that produces unexpectedly high conversion rates for both , CO, and HC. The process of the present invention also shortens process run times and reduces catalyst costs.

[0009] One aspect of the present disclosure is directed to a catalyst article for treating exhaust gases, the catalyst article comprising: a substrate including an inlet end and an outlet end having an axial length L; an inlet catalyst layer beginning at the inlet end and extending to an axial length of less than L, the inlet catalyst layer comprising an inlet palladium component; and an outlet catalyst layer beginning at the outlet end and extending to an axial length of less than L, the outlet catalyst layer comprising an outlet rhodium component; wherein the outlet catalyst layer overlaps the inlet catalyst layer.

[0010] The catalyst article of the present invention can have three catalyst zones along the axis of the substrate: an upstream zone coated with only an inlet catalyst layer, a middle zone coated with both an inlet and an outlet catalyst layer, and a downstream zone coated with only an outlet catalyst layer.

[0011] The inventors have discovered that these catalysts with various orientations provide synergistic effects in both improving catalyst performance and reducing backpressure, which are not achieved when using the catalysts separately or in conventional orientations. Unexpected benefits of the present invention include reduced backpressure compared to conventional TWC catalysts of similar concentration (washcoat loading), and improved catalyst performance compared to conventional TWC catalysts, even at higher concentrations of conventional TWC. These benefits translate to improved engine performance, improved fuel economy, and reduced costs.

[0012] The inlet catalyst layer of the catalyst article can extend over 50 to 99% of the axial length L. Preferably, the inlet catalyst layer can extend over 55 to 95%, 60 to 90%, and more preferably 65 to 85% of the axial length L (see, for example, Figures 1 and 2).

[0013] The outlet catalyst layer of the catalyst article can extend over 50 to 99% of the axial length L. Preferably, the outlet catalyst layer can extend over 55 to 95%, 60 to 90%, and more preferably 65 to 85% of the axial length L (see, e.g., Figures 1 and 2).

[0014] The inlet catalyst layer may be essentially free of PGM metals other than the inlet palladium component.

[0015] The inlet catalyst layer may contain PGM metals other than the inlet palladium component, such as platinum and / or rhodium. The inlet catalyst layer may contain up to 300 g / ft 3 Preferably, the inlet catalyst layer contains 10 to 200 g / ft of inlet palladium or platinum-palladium component. 3 , more preferably 20 to 150 g / ft 3 The inlet palladium or platinum palladium component may comprise the above, and the weight ratio of platinum to palladium may be 60:1 to 1:60, preferably 30:1 to 1:30, more preferably 10:1 to 1:10.

[0016] The inlet catalyst layer may further comprise an inlet inorganic oxide material, an oxygen storage capacity (OSC) material, an inlet alkali metal or alkaline earth metal component, and / or an inlet inorganic oxide.

[0017] The total washcoat loading in the inlet catalyst layer is 0.1 to 5 g / in 3 Preferably, the total washcoat loading of the inlet catalyst layer is 0.5 to 3.5 g / in 3 and most preferably, the total washcoat loading of the inlet catalyst layer is 1 to 2.5 g / in 3 is.

[0018] The inlet 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 inlet OSC material comprises ceria-zirconia mixed oxide. The ceria-zirconia mixed oxide may further comprise some dopants such as La, Nd, Y, Pr, etc.

[0019] The ceria-zirconia mixed oxide can have a molar ratio of zirconia to ceria of at least 50:50, preferably greater than 60:40, and more preferably greater than 75:25. Additionally, the inlet OSC material can function as a support material for the inlet palladium component.

[0020] The inlet OSC material (eg, ceria-zirconia mixed oxide) can be 10-90 wt %, preferably 25-75 wt %, more preferably 35-65 wt %, based on the total washcoat loading of the inlet catalyst layer.

[0021] The inlet OSC material loading in the inlet catalyst layer was 1.5 g / in 3 In some embodiments, the inlet OSC material loading in the inlet catalyst layer may be less than 1.2 g / in 3 , 1.0g / in 3 , 0.9g / in 3 , 0.8g / in 3 , 0.7g / in 3 , or 0.6 g / in 3 The following is the result.

[0022] In some embodiments, the inlet alkali metal or alkaline earth metal may be deposited on the inlet OSC material. Alternatively, or in addition, the inlet alkali metal or alkaline earth metal may be deposited on the inlet inorganic oxide. That is, in some embodiments, the inlet alkali metal or alkaline earth metal may be deposited on, or present on, both the inlet OSC material and the inlet inorganic oxide.

[0023] Preferably, the inlet alkali metal or alkaline earth metal is supported / deposited on an inlet inorganic oxide (e.g., alumina). In addition to or instead of being in contact with the inlet inorganic oxide, the inlet alkali metal or alkaline earth metal may also be in contact with the inlet OSC material and the inlet palladium component.

[0024] The inlet alkali metal or alkaline earth metal is preferably barium or strontium. Preferably, the barium or strontium, if present, is present in an amount of 0.1 to 15 wt. % barium, more preferably 3 to 10 wt. % barium, based on the total weight of the inlet catalyst layer.

[0025] Preferably, the barium is present as BaCO. Such materials can be prepared by any method known in the art, such as incipient wetness impregnation or spray drying.

[0026] The inlet inorganic oxide is preferably an oxide of an element of Groups 2, 3, 4, 5, 13, and 14. The inlet inorganic oxide is preferably selected from the group consisting of alumina, ceria, magnesia, silica, niobia, lanthanum, zirconium, neodymium, praseodymium oxide, and mixed oxides or composite oxides thereof. Particularly preferably, the inlet inorganic oxide is alumina, lanthanum / alumina composite oxide, or magnesia / alumina composite oxide. One particularly preferred inlet inorganic oxide is lanthanum / alumina composite oxide or magnesia / alumina composite oxide. The inlet inorganic oxide may be a support material for the inlet palladium component and / or a support material for the inlet alkali metal or alkaline earth metal.

[0027] The preferred inlet inorganic oxide is preferably 80 m 2 / g and pore volumes in the range of 0.1 to 4 mL / g. 2High surface area inorganic oxides, such as high surface area alumina, having a surface area of ​​greater than 1 / g are particularly preferred. Other preferred inlet inorganic oxides include lanthanum / alumina composite oxides, which optionally further contain a cerium-containing component, such as ceria. In such cases, ceria may be present on the surface of the lanthanum / alumina composite oxide, for example, as a coating.

[0028] The inlet OSC material and the inlet 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.

[0029] Alternatively, the inlet OSC material and the inlet inorganic oxide may 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.

[0030] The outlet catalyst layer may be essentially free of PGM metals other than the outlet rhodium component.

[0031] Outlet catalyst layer: 1 to 20 g / ft 3 Preferably, the outlet catalyst layer contains 2 to 15 g / ft of an outlet rhodium or platinum-rhodium component. 3 , more preferably 3 to 10 g / ft 3 The outlet rhodium or platinum-rhodium component may comprise the above, and the weight ratio of platinum to rhodium may be 20:1 to 1:20, preferably 15:1 to 1:15, more preferably 10:1 to 1:10.

[0032] The total washcoat loading in the outlet catalyst layer is 0.1 to 3.5 g / in 3 Preferably, the total washcoat loading of the outlet catalyst layer is 0.5 to 3 g / in 3 and most preferably, the total washcoat loading of the outlet catalyst layer is 0.6 to 2 g / in 3 is.

[0033] The outlet catalyst layer may further comprise an outlet oxygen storage capacity (OSC) material, an outlet alkali metal or alkaline earth metal component, and / or an outlet inorganic oxide.

[0034] The outlet 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 outlet OSC material comprises ceria-zirconia mixed oxide. The ceria-zirconia mixed oxide may further comprise certain dopants, such as lanthanum, neodymium, praseodymium, and yttrium.

[0035] The ceria-zirconia mixed oxide may have a molar ratio of zirconia to ceria of at least 50:50, preferably greater than 60:40, and more preferably greater than 80:20. Additionally, the outlet OSC material may function as a support material for the outlet rhodium component.

[0036] The outlet OSC material (eg, bulk ceria) can be 10-90 wt %, preferably 25-75 wt %, more preferably 35-65 wt %, based on the total washcoat loading of the outlet catalyst layer.

[0037] The outlet OSC material loading in the outlet catalyst layer was 1.5 g / in 3 In some embodiments, the outlet OSC material loading in the outlet catalyst layer may be less than 1.2 g / in 3 , 1.1g / in 3 , or 1.0 g / in 3 The following is the result.

[0038] The outlet alkali metal or alkaline earth metal is preferably barium or strontium. Preferably, the barium or strontium, if present, is present in an amount of 0.1 to 15 wt. % barium, more preferably 3 to 10 wt. % barium, based on the total weight of the outlet catalyst layer.

[0039] Preferably, the barium is present as BaCO. Such materials can be prepared by any method known in the art, such as incipient wetness impregnation or spray drying.

[0040] The outlet catalyst layer is preferably substantially free of outlet alkali metals or alkaline earth metals. More preferably, the outlet catalyst layer is essentially free of outlet alkali metals or alkaline earth metals.

[0041] The output inorganic oxide is preferably an oxide of an element of Groups 2, 3, 4, 5, 13, and 14. The output inorganic oxide is preferably selected from the group consisting of alumina, ceria, magnesia, silica, niobia, lanthanum, zirconium, neodymium, praseodymium oxide, and mixed oxides or composite oxides thereof. Particularly preferred is alumina, lanthanum / alumina composite oxide, or magnesia / alumina composite oxide. One particularly preferred output inorganic oxide is lanthana / alumina composite oxide, magnesia / alumina, or zirconium / alumina composite oxide. The output inorganic oxide may also be a support material for the output rhodium component.

[0042] The outlet OSC material and the outlet 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 less, and most preferably 3:1 or less.

[0043] Alternatively, the outlet OSC material and the outlet inorganic oxide may 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, and most preferably 3:1 to 1:3.

[0044] In some embodiments, the weight ratio of the outlet rhodium component to the inlet palladium component is between 60:1 and 1:60. Preferably, the weight ratio of the outlet rhodium component to the inlet palladium component is between 30:1 and 1:30. More preferably, the weight ratio of the outlet rhodium component to the inlet palladium component is between 20:1 and 1:20. Most preferably, the weight ratio of the outlet rhodium component to the inlet palladium component is between 15:1 and 1:15.

[0045] 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 contain at least one binder and / or at least one surfactant. When a binder is present, a dispersible alumina binder is preferred.

[0046] Preferably, the substrate is a flow-through monolith or a wall-flow gasoline particulate filter. More preferably, the substrate is a flow-through monolith.

[0047] The substrate may be less than 100 mm in length, preferably between 50 and 90 mm.

[0048] 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.

[0049] The first surface is typically at the inlet end of the substrate and the second surface is at the outlet end of the substrate.

[0050] The channels may be of constant width, and each of the plurality of channels may have a uniform channel width.

[0051] Preferably, in a plane perpendicular to the longitudinal direction, the monolith substrate has 100 to 900 channels per square inch, preferably 300 to 750 channels per square inch. For example, on the first face, the density of the open first channels and closed second channels is 300 to 750 channels per square inch. The channels may have cross sections that are rectangular, square, circular, oval, triangular, hexagonal, or other polygonal shapes.

[0052] The monolith substrate acts as a support material 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.

[0053] It should be noted that the flow-through monolith substrates described herein are unitary components (i.e., a single brick). Nevertheless, when forming an exhaust treatment system, the monolith used may be formed by bonding together multiple channels, or may be formed by bonding together multiple smaller monoliths as described herein. Such techniques, along with suitable casings and configurations of exhaust treatment systems, are known in the art.

[0054] 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, titania, 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.

[0055] 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 refractory 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.

[0056] As shown in Figure 1, the inlet catalyst layer is completely supported / deposited directly on the substrate. The outlet catalyst layer is partially supported / deposited directly on the substrate and partially supported / deposited on top of the inlet catalyst layer. Thus, the intermediate zone includes both the inlet and outlet catalyst layers.

[0057] As shown in Figure 2, the outlet catalyst layer is completely supported / deposited directly on the substrate. The inlet catalyst layer is partially supported / deposited directly on the substrate and partially supported / deposited on top of the outlet catalyst layer. Thus, the intermediate zone includes both the outlet catalyst layer and the inlet catalyst layer.

[0058] Another aspect of the present disclosure is a method for producing NOx using the catalytic articles described herein. x Catalytic converters equipped with TWCs made according to the present invention not only exhibit improved or comparable catalytic performance compared to conventional TWCs, but also exhibit significant improvements in backpressure (see, e.g., Examples 1 and 2 and Tables 1 and 2).

[0059] Another aspect of the present disclosure relates to a system for treating vehicle exhaust gases that includes a catalytic article as described herein along with a conduit for transporting the exhaust gases through the system.

[0060] definition The term "washcoat" is known in the art and refers to an adherent coating that is typically applied to a substrate during the manufacture of a catalyst.

[0061] 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.

[0062] 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.

[0063] 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, e.g., trace impurities, that do not substantially affect the basic properties of the feature. The phrase "consisting essentially of" encompasses the phrase "consisting of."

[0064] As used herein with respect to a material, the term "substantially free" typically means that the material is present in a small amount, e.g., <5% by weight, preferably <2% by weight, more preferably <1% by weight, relative to the contents of a region, layer, or zone. The term "substantially free" encompasses the term "free."

[0065] The term "essentially free" as used herein with respect to a material typically refers to trace amounts of the material, such as ≦1% by weight, preferably ≦0.5% by weight, and more preferably ≦0.1% by weight, relative to the contents of a region, layer, or zone. The term "essentially free" encompasses the term "free."

[0066] 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.

[0067] As used herein, the term "loading" refers to g / ft on a metal weight basis. 3 Refers to a measurement in units of .

[0068] 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]

[0069] material All materials were commercially available and obtained from known sources unless otherwise stated.

[0070] Catalyst 1 (comparison) Catalyst 1 is a commercially available ternary (Pd-Rh) catalyst with a double-layer structure (e.g., as shown in Figure 3). The bottom layer consists of Pd supported on a first CeZr mixed oxide, La-stabilized alumina, and a Ba-promoter washcoat. The washcoat loading of the bottom layer is approximately 2.2 g / in. 3 The Pd loading is 75 g / ft 3 The top layer consisted of a second CeZr mixed oxide and Rh supported on a washcoat of La-stabilized alumina. The washcoat loading of the top layer was approximately 1.6 g / in 3 The Rh loading is 5g / ft 3 The total washcoat loading of catalyst 1 was approximately 3.8 g / in 3 It was.

[0071] Catalyst 2 Catalyst 2 was prepared according to the present invention. The bottom layer consisted of Pd supported on an inlet CeZr mixed oxide, La-stabilized alumina, and a Ba-promoter washcoat. The washcoat loading of the bottom layer was approximately 2.2 g / in. 3 The Pd loading is 75 g / ft 3 The top layer consisted of a CeZr mixed oxide and Rh supported on a washcoat of La-stabilized alumina. The washcoat loading of the top layer was approximately 1.6 g / in. 3The Rh loading is 5g / ft 3 The total washcoat loading of catalyst 2 (middle zone) was approximately 3.8 g / in 3 It was.

[0072] The final Pd-containing bottom layer slurry was coated from the inlet face of the same substrate as Comparative Catalyst 1 using standard coating procedures to a target coating depth of 80% of the substrate's length and dried at 90° C. The Rh-containing top layer slurry was then coated from the outlet face of the dried bottom layer-containing substrate using standard coating procedures to a target coating depth of 80% of the substrate's length, followed by drying at 90° C. and calcination at 500° C. for 45 minutes.

[0073] Catalyst 3 Catalyst 3 was prepared according to the present invention. The bottom layer consisted of Pd supported on an inlet CeZr mixed oxide, La-stabilized alumina, and a Ba-promoter washcoat. The washcoat loading of the bottom layer was approximately 1.9 g / in. 3 The Pd loading is 75 g / ft 3 The upper layer consisted of a Ce-Zr mixed oxide and Rh supported on a washcoat of La-stabilized alumina. The washcoat loading of the upper layer was approximately 1.5 g / in. 3 The Rh loading is 5g / ft 3 The total washcoat loading of catalyst 3 (middle zone) was about 3.4 g / in 3 It was.

[0074] Using standard coating procedures, the final Pd-containing bottom layer slurry was coated from the inlet face of the same substrate as Comparative Catalyst 1, with a target coating depth of 80% of the substrate's length, and dried at 90° C. Then, using standard coating procedures, the Rh-containing top layer slurry was coated from the outlet face of the dried bottom layer-containing substrate, with a target coating depth of 80% of the substrate's length, and then dried at 90° C. and calcined at 500° C. for 45 minutes.

[0075] Catalyst 4 Catalyst 4 was prepared according to the present invention. The bottom layer consisted of Pd supported on an inlet CeZr mixed oxide, La-stabilized alumina, and a Ba-promoter washcoat. The washcoat loading of the bottom layer was approximately 1.7 g / in. 3 The Pd loading is 75 g / ft 3 The top layer consisted of a CeZr mixed oxide and Rh supported on a washcoat of La-stabilized alumina. The washcoat loading of the top layer was approximately 1.3 g / in. 3 The Rh loading is 5g / ft 3 The total washcoat loading of catalyst 4 (middle zone) was approximately 3.0 g / in 3 It was.

[0076] Using standard coating procedures, the final Pd-containing bottom layer slurry was coated from the inlet face of the same substrate as Comparative Catalyst 1, with a target coating depth of 80% of the substrate's length, and dried at 90°C. Then, using standard coating procedures, the Rh-containing top layer slurry was coated from the outlet face of the substrate containing the dried bottom layer, with a target coating depth of 80% of the substrate's length, and then dried at 90°C and calcined at 500°C for 45 minutes.

[0077] Experimental results Example 1 Comparative Catalyst 1 and Catalysts 2-4 were bench aged for 200 hours in a four-mode aging cycle with a peak temperature of approximately 980°C. Vehicle emissions were measured in a commercial vehicle with a 1.4-liter engine. Emissions were measured before and after the catalyst.

[0078] [Table 1]

[0079] As shown in Table 1, Catalyst 4, even with a lower total washcoat loading of approximately 80% like Comparative Catalyst 1, exhibited comparable or even improved catalytic performance (e.g., see the improved performance related to THC / NMHC emissions, from 0.047 / 0.031 g / km to 0.042 / 0.026 g / km, an 11% and 16% improvement, respectively, for Catalyst 4 compared to Comparative Catalyst 1).

[0080] Example 2 Comparative Catalyst 1, Catalyst 2, and Catalyst 4 were coated on the same substrate type, cpsi, and dimensions and then measured at 200, 300, 400, and 600 m 3 The cold flow back pressure at an air flow rate of 1 / hr was evaluated.

[0081] The percentage increase in backpressure over bare substrate for Comparative Catalyst 1, Catalyst 2, and Catalyst 4 is shown in Table 2. The data shows that multi-zoned Catalyst 4 contributes significantly less to backpressure than the standard two-layer example of Catalyst 1.

[0082] [Table 2] The disclosure of the present invention may include the following aspects. (Aspect 1) 1. A catalytic article for treating exhaust gases, comprising: a substrate including an inlet end and an outlet end having an axial length L; an inlet catalyst layer beginning at the inlet end and extending to less than the axial length L, the inlet catalyst layer comprising an inlet palladium component; an outlet catalyst layer beginning at the outlet end and extending for less than the axial length L, the outlet catalyst layer comprising an outlet rhodium component; The catalyst article, wherein the outlet catalyst layer overlaps the inlet catalyst layer. (Aspect 2) 2. The catalyst article of claim 1, wherein the inlet catalyst layer extends over 50 to 99% of the axial length L. (Aspect 3) A catalyst article according to aspect 1 or 2, wherein the outlet catalyst layer extends over 50 to 99% of the axial length L. (Aspect 4) A catalyst article according to any one of aspects 1 to 3, wherein the outlet catalyst layer overlaps with the inlet catalyst layer over 5 to 90% of the axial length L. (Aspect 5) A catalyst article according to any one of aspects 1 to 4, wherein the outlet catalyst layer overlaps with the inlet catalyst layer over 40 to 80% of the axial length L. (Aspect 6) A catalyst article according to any one of aspects 1 to 5, wherein the inlet catalyst layer is essentially free of PGM metals other than the inlet palladium component. (Aspect 7) The inlet layer has a maximum of 300 g / ft 3 A catalytic article according to any one of aspects 1 to 6, comprising the inlet palladium component of (Aspect 8) A catalyst article according to any one of aspects 1-7, wherein the outlet catalyst layer is essentially free of PGM metals other than the outlet rhodium component. (Aspect 9) The outlet layer has a thickness of 1 to 20 g / ft 3 A catalyst article according to any one of aspects 1 to 8, comprising the outlet rhodium component of (Aspect 10) 10. The catalyst article of any one of aspects 1-9, wherein the inlet catalyst layer further comprises an inlet oxygen storage capacity (OSC) material, an inlet alkali metal or alkaline earth metal component, and / or an inlet inorganic oxide. (Aspect 11) 11. The catalytic article of embodiment 10, wherein the inlet OSC material is selected from the group consisting of cerium oxide, zirconium oxide, ceria-zirconia mixed oxide, and alumina-ceria-zirconia mixed oxide. (Aspect 12) 12. The catalytic article of embodiment 11, wherein the inlet OSC material comprises the ceria-zirconia mixed oxide. (Aspect 13) 13. The catalyst article of any one of aspects 10-12, wherein the inlet palladium component is supported on the inlet inorganic oxide. (Aspect 14) 14. The catalyst article of any one of aspects 10 to 13, wherein the inlet inorganic oxide is selected from the group consisting of alumina, ceria, magnesia, silica, lanthanum, neodymium, praseodymium, yttrium oxides, and mixed or composite oxides thereof. (Aspect 15) 15. The catalytic article of embodiment 14, wherein the inlet inorganic oxide is alumina, a lanthanum / alumina composite oxide, or a magnesia / alumina composite oxide. (Aspect 16) 16. The catalytic article of any one of aspects 10 to 15, wherein the inlet alkali metal or alkaline earth metal is barium or strontium. (Aspect 17) 17. The catalyst article of embodiment 16, wherein the barium or strontium is present in the inlet catalyst layer in an amount of 0.1 to 15 wt %, based on the total weight of the inlet catalyst layer. (Aspect 18) 18. The catalyst article of any one of aspects 1-17, wherein the outlet catalyst layer further comprises an outlet oxygen storage capacity (OSC) material, and / or an outlet inorganic oxide. (Aspect 19) 20. The catalytic article of embodiment 18, wherein the outlet OSC material is selected from the group consisting of cerium oxide, zirconium oxide, ceria-zirconia mixed oxide, and alumina-ceria-zirconia mixed oxide. (Aspect 20) 20. The catalytic article of embodiment 19, wherein the outlet OSC material comprises the ceria-zirconia mixed oxide. (Aspect 21) 21. The catalyst article of any one of aspects 18 to 20, wherein the outlet inorganic oxide is selected from the group consisting of alumina, zirconia, magnesia, silica, lanthanum, yttrium, neodymium, and praseodymium oxides, and mixed or composite oxides thereof. (Aspect 22) 22. The catalytic article of claim 21, wherein the outlet inorganic oxide is alumina, a lanthana / alumina composite oxide, or a magnesia / alumina composite oxide. (Aspect 23) 23. The catalytic article of any one of aspects 1 to 22, wherein the substrate is a flow-through monolith or a wall-flow filter. (Aspect 24) 24. The catalyst article of any one of aspects 1-23, wherein the substrate is less than 100 mm in length. (Aspect 25) 25. The catalyst article of any one of aspects 1-24, wherein the inlet catalyst layer is supported / deposited directly on the substrate. (Aspect 26) 26. The catalyst article of any one of aspects 1 to 25, wherein the outlet catalyst layer is supported / deposited directly on the substrate. (Aspect 27) An emissions treatment system for treating a combustion exhaust gas stream comprising the catalytic article of any one of embodiments 1-26. (Aspect 28) A method for treating exhaust gas from an internal combustion engine, comprising contacting the exhaust gas with the catalytic article of any one of aspects 1-26.

Claims

1. 1. A catalytic article for treating exhaust gases, comprising: a substrate including an inlet end and an outlet end having an axial length L; an inlet catalyst layer beginning at the inlet end and extending over 65 to 85% of the axial length L, the inlet catalyst layer comprising an inlet palladium component; an outlet catalyst layer beginning at the outlet end and extending over 65 to 85% of the axial length L, the outlet catalyst layer comprising an outlet rhodium component; the outlet catalyst layer overlaps the inlet catalyst layer; the inlet catalyst layer does not contain any PGM metals other than the inlet palladium component; A catalyst article wherein said outlet catalyst layer does not contain any PGM metals other than the outlet rhodium component.

2. 10. The catalyst article of claim 1, wherein the inlet catalyst layer further comprises an inlet oxygen storage capacity (OSC) material, an inlet alkali metal or alkaline earth metal component, and / or an inlet inorganic oxide.

3. 3. The catalyst article of claim 1 or 2, wherein the outlet catalyst layer further comprises an outlet oxygen storage capacity (OSC) material and / or an outlet inorganic oxide.

4. The catalytic article of any one of claims 1 to 3, wherein the substrate is a flow-through monolith or a wall-flow filter.

5. The catalytic article of any one of claims 1 to 4, wherein the substrate has a length of 50 to 100 mm.

6. The catalyst article according to any one of claims 1 to 5, wherein the inlet catalyst layer is supported directly on the substrate.

7. The inlet catalyst layer extends over 80% of the axial length L, 7. The catalyst article of claim 1, wherein the outlet catalyst layer extends over 80% of the axial length L.

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