BR112017027715B1 - AUTOMOTIVE CATALYST COMPOSITE, AND, SYSTEM AND METHOD FOR EXHAUST GAS TREATMENT - Google Patents

Abstract

AUTOMOTIVE CATALYST COMPOSITE, AND, SYSTEM AND METHOD FOR EXHAUST GAS TREATMENT. Automotive catalyst composites having a catalytic material in a carrier are provided, wherein the catalytic material comprises at least two layers. The first layer is deposited directly on the carrier and comprises a first palladium component supported on a first refractory metal oxide component, a first oxygen storage component, or a combination thereof. The second layer is deposited on top of the first layer and comprises a rhodium component supported on a second refractory metal oxide component and a second palladium component supported on a second oxygen storage component, a third refractory metal oxide component or a combination thereof. Generally, these catalyst composites are used as three-way conversion catalysts (TWC). Methods for making and using the same are also provided.

Description

TECHNICAL FIELD OF THE INVENTION

[001] This invention generally relates to layered automotive composites and catalysts and emission treatment systems that use such catalysts to treat gasoline engine exhaust streams containing hydrocarbons, carbon monoxide and nitrogen oxides. More specifically, this invention is directed to three-way conversion (TWC) catalysts having rhodium and palladium on different supports present on the same top layer, which is coated on top of a palladium-containing bottom layer that is deposited on a substrate such as as a monolithic carrier.

BASICS OF THE INVENTION

[002] Emission standards for unburned hydrocarbon contaminants, carbon monoxide and nitrogen oxide continue to become more stringent. In order to meet such standards, catalytic converters containing a three-way conversion catalyst (TWC) are located in the exhaust gas line of internal combustion engines. Such catalysts promote the oxidation by oxygen in the exhaust gas stream of unburned hydrocarbons (HC) and carbon monoxide (CO), as well as the reduction of nitrogen oxides (NOx) to nitrogen. Generally, TWC catalysts substantially simultaneously oxidize carbon monoxide and hydrocarbons and reduce nitrogen oxide.

[003] Many TWC catalysts are manufactured with at least two separate catalyst coating compositions (reactive coatings) that are applied in the form of aqueous dispersions as successive layers on a substrate (e.g., a honeycomb body composed of ceramic or metal) to in order to separate platinum group metals (PGM) such as palladium and rhodium, which represent the main catalytically active species. The separation has been considered necessary because palladium and rhodium can form an alloy, which is known to be less catalytically active.

[004] U.S. Patent Application Publication No. 2014/0205523, incorporated herein by reference, is directed to automotive catalyst composites having a layer containing two metals, wherein the layer containing two metals is formed from a single layer of reactive coating. This reactive coating layer contains two PGMs, each of which is on its own support, resulting in a homogeneous mixture of the two PGMs supported on the same layer. This layer is coated on a carrier.

[005] There is a continued need to provide TWC catalyst composites that utilize metals (e.g., PGMs) efficiently and remain effective in satisfying regulated conversions of HC, NOx and CO.

SUMMARY OF THE INVENTION

[006] Automotive catalyst composites having a layer of two metals on a carrier and methods of producing and using these catalyst composites are provided.

[007] In a first aspect, the description provides automotive catalyst composites comprising: a catalytic material on a carrier, the catalytic material comprising at least two layers: a first layer deposited directly on the carrier comprising a first palladium component supported on a first refractory metal oxide component, a first oxygen storage component, or a combination thereof; a second layer deposited on top of the first layer comprising a rhodium component supported on a second refractory metal oxide component and a second palladium component supported on a second oxygen storage component, a third refractory metal oxide component or a combination thereof, in which the catalytic material is effective to perform three-way conversion (TWC).

[008] In one or more embodiments, the first layer is substantially free of any other platinum group metals. The first layer may further comprise barium oxide, strontium oxide, or combinations thereof. The first layer may comprise about 40-95% (or even about 65-90%) by weight of the total palladium content of the composite and the second layer comprises about 5-60% (or even about 10-35% ) by weight of the total palladium content of the composite. The second layer may comprise a weight ratio of the palladium component to the rhodium component in the range of about 0.1:1 to about 20:1 (or about 0.5:1 to about 10:1, or even about 1:1 to about 5:1). In the first layer, the palladium component may be supported on both the first refractory metal oxide component and the first oxygen storage component, the first refractory metal oxide component comprising a stabilized alumina and the first oxygen storage component comprising about 25-50% by weight of ceria based on the total weight of the first oxygen storage component. The stabilized alumina of the first refractory metal oxide component may comprise activated alumina, lantana-alumina, baria-alumina, ceria-alumina, ceria-lantana-alumina, zirconia-alumina, ceria-zirconia-alumina, or combinations thereof. In the second layer, the second refractory metal oxide component for supporting the rhodium component may comprise an alumina-based support or a zirconia-based support. The second refractory metal oxide component for supporting the rhodium component may comprise an activated alumina compound selected from the group consisting of alumina, stabilized zirconia-alumina, lantana-alumina, baria-alumina, ceria-alumina, zirconia-alumina , ceria-zirconia-alumina, lantana-zirconia-alumina, baria-lantana-alumina, baria-lantana-neodymia alumina and combinations thereof. The second refractory metal oxide component for supporting the rhodium component may comprise about 20% by weight of stabilized zirconia-alumina based on the total weight of the second refractory metal oxide component. The second refractory metal oxide component for supporting the rhodium component may comprise a zirconia-based support selected from the group consisting of zirconia, lantana-zirconia, titania-zirconia, titania-lantana-zirconia and combinations thereof. The second palladium component of the second layer may be supported on the second oxygen storage component comprising a ceria-zirconia composite comprising about 10-50% by weight ceria based on the total weight of the second oxygen storage component. The second palladium component of the second layer may be supported on the third refractory metal oxide component comprising alumina, stabilized alumina, praseodymium-zirconia, or combinations thereof.

[009] The first layer may comprise, in percentage by weight of the first layer: the first refractory metal oxide component in an amount of about 50-95% (or even about 20-80%); the first oxygen storage component comprising a first ceria-zirconia composite in an amount of about 20-80%; and at least one promoter or stabilizer selected from lantana, baria, zirconia and strontium in an amount of up to about 10% (or about 0.110%, or about 0.1-5%); wherein the first ceria-zirconia composite comprises ceria in an amount of about 25-50% by weight of the first ceria-zirconia composite.

[0010] The second layer may comprise, in percentage by weight of the second layer: the second refractory metal oxide component in an amount of about 50-80%; and the second oxygen storage component comprising a ceria-zirconia composite or the third refractory metal oxide component in an amount of about 20-50%; at least one promoter or stabilizer selected from lantana, baria, zirconia and strontium in an amount of up to about 10% (or about 0.1-10%, or about 0.1-5%); wherein the second ceria-zirconia composite comprises ceria in an amount of about 10-50% by weight of the second ceria-zirconia composite.

[0011] The total palladium content of the first layer can be supported in the first refractory metal oxide component and about 40-80% of the total palladium content of the first layer is supported in the first oxygen storage component. The palladium content in the first oxygen storage component may be about 0.5-3% by weight of the first oxygen storage component and wherein the first layer optionally additionally comprises palladium in the first refractory metal oxide component.

[0012] The second layer may additionally comprise a platinum component in an amount of about 3.53 to 353.15 g/m3 (0.1 to 10 g/ft3). The automotive catalyst may further comprise a base layer between the carrier and the first layer, wherein the base layer is substantially free of any platinum group metals and comprises alumina. The carrier can be a through-flow substrate or a wall-flow filter. The first layer may be deposited in the inlet channels of a wall flow filter and the layer is deposited in the outlet channels of the wall flow filter.

[0013] The first palladium-containing layer can be zoned. The second layer can be zoned. A first layer filler may be in the range of about 0.09-0.24 g/cm3 (1.5-4.0 g/in3) and a second layer filler is in the range of about 0.04- 0.12 g/cm3 (0.75-2.0 g/in3).

[0014] The automotive catalyst composite may further comprise a palladium-containing intermediate layer between the first layer and the second layer, wherein the first layer comprises the palladium component supported on the first oxygen storage component and the intermediate layer comprises a palladium component. palladium supported on a fourth refractory metal oxide component and is substantially free of an oxygen storage component.

[0015] A further aspect is an exhaust gas treatment system comprising any catalyst composite described herein located downstream of a gasoline engine. The automotive catalyst composite may be located downstream of a gasoline engine in a closely coupled position, in a position downstream of the closely coupled position, or both.

[0016] Another aspect is a method for treating exhaust gas comprising hydrocarbons, carbon monoxide and nitrogen oxides which comprises: contacting the exhaust gas with any automotive catalyst composite described here.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a schematic diagram of a representative catalytic composite according to example 1; FIG. 2 is a schematic diagram of a comparative catalytic composite according to comparative example 3; FIG. 3 is a schematic diagram of a representative catalytic composite according to example 4; FIG. 4 is a schematic diagram of a comparative catalytic composite according to comparative example 5; FIG. 5 is a schematic diagram of a representative catalytic composite according to example 7; FIG. 6 is a schematic diagram of a comparative catalytic composite according to comparative example 8; FIG. 7 is a schematic diagram of a comparative catalytic composite according to comparative example 9; FIG. 8 is a schematic diagram of a gasoline exhaust system; FIG. 9 is an exemplary catalyst composite showing a zoned first layer on a through-flow substrate; FIG. 10 is another exemplary catalyst composite showing a zoned first layer on a through-flow substrate; FIG. 11 is another exemplary catalyst composite showing a zoned first layer on a through-flow substrate; FIG. 12 is an exemplary catalyst composite showing a second layer zoned within a first layer, which is on a flow-through substrate; FIG. 13 is an exemplary catalyst composite having a palladium-containing intermediate layer between the first layer and the second layer; FIG. 14 is an exemplary catalyst composite having a palladium-containing zoned intermediate layer between the first layer and the second layer; FIG. 15 is a perspective view of a wall flow filter substrate; and FIG. 16 is a sectional view of a wall flow filter substrate.

DETAILED DESCRIPTION OF THE INVENTION

[0018] The present disclosure provides automotive catalyst composites having a two-metal (i.e., palladium-rhodium (Pd-Rh)) layer (the “top layer” or “second layer”) coated on top of a layer containing palladium (Pd) (the “bottom layer” or “first layer”) that is arranged directly on a carrier. Methods of producing and using these catalyst composites are also provided herein. The Pd and Rh in the top layer are in individual support materials. In one or more embodiments, the Pd-containing layer is a Pd-only layer, that is, there are no other platinum group metals (PGMs) present in the layer. However, in other embodiments, a platinum component is also present in the layer.

[0019] Such a design improves catalytic activity for hydrocarbons (HC) and nitrogen oxides (NOx) by increasing the accessibility of the exhaust gas to the metals Pd and Rh in the top layer. Choosing support materials for Pd and Rh also improves their accessibility. For example, NOx conversion can be enhanced by supporting Pd in a particular oxygen storage component (OSC) in the top layer. The ignition temperature of HC can be enhanced by using Pd/alumina or different combinations of alumina and OSC in one of the layers. For example, different Pd and Rh support materials can be used depending on the exhaust gas (NOx, HC, or CO) that needs to be reduced. The Pd in the top layer can be in the range of about 5-60% by weight of the total palladium present in the catalyst composite. The Rh in the top layer can be supported on refractory metal oxide supports such as an alumina-based support and/or a zirconia-based support.

[0020] The top layer is formed from a reactive coating layer that contains two platinum group metals, each of which is on its own support, resulting in a homogeneous mixture of the two supported metals present on the same coated layer on a carrier. The top reactive coating layer is designed to contain an activated alumina component to support rhodium, as well as an activated alumina component and/or a ceria-zirconia composite to support palladium.

[0021] In some embodiments, such automotive catalyst composite further comprises a base layer located between the carrier and the top layer, wherein the base layer is substantially free of any PGMs and comprises alumina.

[0022] In some embodiments, the automotive catalyst composite additionally comprises a palladium-containing intermediate layer between the top layer and the bottom layer. In some examples, the intermediate layer comprises a palladium component supported on a refractory metal oxide component. In some embodiments, the palladium-containing intermediate layer is substantially free of an oxygen storage component.

[0023] One or more of the platinum group metals (PGMs) present in any reactive coating layer are fixed to their individual support, which means that the PGM is not soluble in the reactive coating dispersion dispersion. Fixation of PGMs can occur by chemical or thermal fixation. For thermal fixation, to produce a “thermally fixed” PGM, it is understood that the impregnated supports are heat treated so that the PGMs are converted to their oxide forms and that when using the heat-fixed PGMs on the supports in a slurry aqueous, PGMs are not soluble and do not mix/agglomerate. For chemical fixation, the pH or some other parameter of the supported PGM salt dispersion is changed to make the PGM insoluble in the reactive coating dispersion. Without wishing to be bound by theory, it is thought that the thermally fixed PGM contained in the layer of two homogeneously mixed metals minimizes the migration of PGMs, especially rhodium.

[0024] Reference to “oxygen storage component” (OSC) refers to an entity that has a multiple valence state and can actively react with oxidants such as oxygen or nitrous oxide under oxidative conditions, or react with reductants such as monoxide of carbon (CO) or hydrogen under reducing conditions. Typically, the OSC will comprise one or more reducible oxides of one or more rare earth metals. Examples of suitable oxygen storage components include ceria, praseodymia, or combinations thereof. The distribution of ceria within the layer can be achieved by using, for example, ceria, a mixed oxide of cerium and zirconium, and/or a mixed oxide of cerium, zirconium, yttrium, lanthanum, or optionally neodymium.

[0025] Reference to a “support” in a catalyst reactive coating layer refers to a material that receives PGMs, stabilizers, promoters, binders and the like through association, dispersion, impregnation, or other appropriate methods. Examples of supports include, but are not limited to, high surface area refractory metal oxides and composites containing oxygen storage components. Exemplary support materials are high surface area aluminum oxide (>80, 90, 100, 125, or even 150 m2/g) (in various modifications), zirconium oxide components that can be combined with stabilizers such as lantana (i.e., Zr-La composites) and oxygen storage components (i.e., cerium-zirconium mixed oxides in various embodiments). Exemplary high surface area refractory metal oxides may comprise a stabilized alumina and/or an activated alumina compound selected from the group consisting of alumina, lantana-alumina, baria-alumina, ceria-alumina, zirconia-stabilized alumina, zirconia -alumina, ceria-zirconia-alumina, lantana-zirconia-alumina, baria-lantana-alumina, baria-lantana-neodymia alumina and combinations thereof. Zirconia-based brackets can be selected from the group consisting of zirconia, lantana-zirconia, titania-zirconia, titania-lantana-zirconia and combinations thereof.

[0026] As used herein, “platinum group metal component”, “platinum component (Pt)”, “rhodium component (Rh)”, “palladium component (Pd)”, “iridium component (Ir )”, “ruthenium (Ru) component” and the like refers to the respective compound, platinum group metal complex, or similar that upon calcination or use of the catalyst decomposes or otherwise converts into a catalytically active form , usually metal or metal oxide.

[0027] “Catalytic coating” is a thin, adherent coating of a catalytic or other material applied to a refractory substrate, such as a honeycomb through-flow monolith substrate or a filter substrate, that is sufficiently porous to permit passage through of the same as the gas stream being treated. A “reactive coating layer” therefore is defined as a coating that is comprised of support particles. “BET surface area” has its usual meaning in reference to the Brunauer-Emmett-Teller method for determining surface area by N2 adsorption measurements. Unless otherwise specified, “surface area” refers to the BET surface area.

[0028] In the present description, “%” refers to “% by weight” or “% by mass”, unless otherwise specified.

[0029] As used herein, the term “substantially free” means that there is generally less than about 1% by weight, including less than about 0.75% by weight, less than about 0.5% by weight, weight, less than about 0.25% by weight, or less than about 0.1% by weight, of metal (i.e., a PGM metal) or support material (i.e., OSC) present in the layer reactive coating. In some embodiments, no metal or support material has been intentionally added to the reactive coating layer. In some embodiments, "substantially Pd-free" includes "Pd-free." Likewise, “substantially free from OSC” includes “free from OSC”. It will be recognized by those skilled in the art, however, that during loading/coating, trace amounts of metal or support material may migrate from one reactive coating component to the other, so that trace amounts of metal or support material may be present. in the reactive coating of the catalyst composition.

[0030] As used herein, the term “Pd only” refers to the reactive coating composition having Pd as the only metal intentionally present and which there is generally less than about 1% by weight, including less than about 0. 75% by weight, less than about 0.5% by weight, less than about 0.25% by weight, or less than about 0.1% by weight, of a second metal (i.e. a PGM metal) present in the reactive coating layer. In some embodiments, no metal has been intentionally added to the reactive coating layer.

[0031] As used herein, the term “substantially uniform” means that the catalytic coating(s) containing any metals (e.g., PGM) and/or support materials (e.g., refractory metal oxides) , OSC) were deposited on the carrier in a consistent manner to achieve a uniformly distributed coating of the reactive coating, thus having essentially the same amount of metals and/or support materials deposited on the surface of the carrier.

[0032] A catalytic material “carrier” is a structure that is suitable for withstanding the conditions found in the exhaust streams of combustion engines. A carrier is a ceramic or metal honeycomb structure having thin, parallel gas flow passages extending from one end of the carrier to the other. The passages may be through-flow or they may be alternately blocked as wall-flow filter substrates.

[0033] In general, methods of preparing the bi-metal layer of the catalyst composites described here include the preparation of individual metal compositions that are fixed (e.g., thermally fixed) and optionally well dispersed. As such, individual platinum group metals (PGMs), such as platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), and/or ruthenium (Ru), are applied as nitrate solutions by impregnation on separate support materials to achieve good dispersion. That is, the nitrate solutions are diluted to the highest amount possible while delivering the desired metal load. The individual diluted nitrate solutions are then added to the individual support materials by incipient moisture to form impregnated supports. The impregnated supports are then subsequently fired (thermally fixed) before the aqueous reactive coating dispersion is produced. Burning of the impregnated support materials leads to the conversion of, for example, palladium nitrate and rhodium nitrate into the corresponding oxides. Without planning to be bound by theory, the oxides are thought to be insoluble in water, which helps prevent redissolution of palladium and rhodium. The probability of palladium-rhodium alloy formation is thus decreased while both PGMs are present in the same reactive coating layer.

[0034] Returning to the figures, various design concepts are described. FIG. 8 provides a schematic diagram of a gasoline exhaust system 100 comprising a gasoline engine 10 and multiple possible locations for the catalysts: the first position 20 is located closest to the gasoline engine and the second position 30 is located downstream of the first. position 20. The first position 20 may be a closely coupled position depending on the automobile design. The second position 30 may be in a position lower than the floor. Inventive catalyst composites may be located in the first position 20, the second position 30, or both.

[0035] In some embodiments, the same carrier is coated with at least two catalyst compositions contained in separate reactive coating slurries in an axially zoned configuration. For example, the same carrier is coated with a reactive coating slurry of one catalyst composition and a reactive coating slurry of another catalyst composition, wherein each catalyst composition is different. This embodiment can be more easily understood by reference to FIG. 9.

[0036] FIG. 9 is an exemplary catalyst composite showing a substantially uniform Pd-Rh top layer disposed on top of a zoned Pd-only bottom layer, which is coated on a flow-through substrate. In this embodiment, the Pd-only bottom layer is zoned to have a “Pd-in zone” and a “Pd-out zone”, wherein the majority of the amount of palladium is present in the front/input zone. PD. In the background layer, the PGM is exclusively Pd. In some embodiments, the Pd present in the entry zone of this layer is about 60-90% of the total Pd background layer. The Pd present in the exit zone of this layer is about 10-40% of the total Pd background layer.

[0037] In some embodiments, Pd is available for the input zone. In further embodiments, such Pd in the entry zone comprises Pd in an OSC in the amount of about 30-70% of the total Pd available to the entry zone (the remaining Pd is in the alumina-based refractory support) and Pd in a refractory metal oxide. In certain embodiments, the composition of the Pd support materials (alumina and an OSC) in both zones is the same. The reactive coating load of the bottom layer is about 0.09-0.24 g/cm3 (1.5-4.0 g/in3), preferably about 0.12-0.18 g/cm3 (2 -3 g/in3). The total amount of OSC in the entry zone is about 50-80% of the total dry weight. The length of the entry zone is about 25-75% of the total length of the carrier. The substantially uniform/homogeneous Pd/Rh top layer is designed as required to meet the needs of a particular application.

[0038] FIG. 10 is another exemplary catalyst composite showing a substantially uniform Pd-Rh top layer disposed on top of a zoned bottom layer, which is coated onto a flow-through substrate. In this embodiment, the Pd-only background layer is zoned to have the majority of palladium in the Pd-only background layer in the front/entrance zone, wherein an OSC is present in both zones. Pd present in the entrance zone is about 60-90% of the total Pd available in the background layer and the OSC in the entrance zone is about 20-80% of the total available OSC present in the background layer. In such embodiments, the Pd in the OSC in the entry zone is greater than (e.g., about twice) the amount of Pd in the OSC in the exit zone. The amount of Pd in the OSC in the exit zone is about 10-40% of the Pd available to the background layer. The amount of an OSC in the exit zone is about 20-80% of the total amount of available OSC available in the background layer. Both the entry and exit zones in the embodiment shown in FIG. 10 further comprise Pd supported on a refractory metal oxide support. The reactive coating load of the bottom layer is about 0.09-0.24 g/cm3 (1.5-4.0 g/in3), preferably about 0.12-0.18 g/cm3 (2 -3 g/in3). The length of the input zone of the bottom layer is generally about 25-75% of the total length of the substrate. The substantially uniform/homogeneous Pd/Rh top layer is designed as required to meet the needs of a particular application.

[0039] FIG. 11 is another exemplary catalyst composite showing a zoned first layer on a through-flow substrate. In this embodiment, the entrance zone of the Pd-only layer is substantially free of OSC. The Pd in the entry zone is about 40-80% of the total Pd available in the bottom layer and the amount of OSC in the entry zone is about zero (i.e., this zone is substantially free of OSC). The exit zone comprises Pd in an OSC, where the Pd in the exit zone is about 20-60% of the total Pd available in the background layer. In the exit zone, the reactive coating load on the OSC is about 80-100% of the total reactive coating. The exit zone may comprise about 100% of the OSC in the layer; binders and optionally other ingredients can be added. The reactive coating load of the entrance zone is about 0.03-0.15 g/cm3 (0.5-2.5 g/in3), preferably about 0.06-0.12 g/cm3 (1 -2 g/in3). The exit zone reactive coating load is about 0.06-0.21 g/cm3 (1.0-3.5 g/in3), preferably about 0.12-0.18 g/cm3 (2 -3 g/in3). The length of the input zone of the bottom layer is about 25-75% of the total length of the substrate. The substantially uniform/homogeneous Pd/Rh top layer is designed as required to meet the needs of a particular application.

[0040] FIG. 12 is an exemplary catalyst composite showing a zoned top layer disposed on a bottom layer, which is coated on a flow-through substrate. In this embodiment, the top Pd/Rh layer is zoned. The Pd present in the substantially uniform bottom layer is about 30-90% of the Pd available to the bottom layer; preferably the Pd present in the bottom layer is about 60-90%. The amounts of Pd and Rh in the input zone are as follows: Pd is about 60-100% of the total Pd available to the top layer and Rh is about 0-80% of the total Rh available. The reactive coating load of the entrance zone is about 0.04-0.09 g/cm3 (0.75-1.5 g/in3). The Pd support of the top layer entrance zone can be stabilized alumina, OSC, La-ZrO2, Pr-CeO2 and the like. The Rh support can be alumina, ZrO2-Al2O3, La-ZrO2 and the like. The amounts of Pd and Rh in the top layer exit zone are as follows: Pd is about 0-40% of the Pd available to the top layer and Rh is about 20-80% of the available Rh. The exit zone reactive coating load may be about 0.04-0.09 g/cm3 (0.75-1.5 g/in3). The Pd support of the top layer exit zone can be stabilized alumina, OSC, La-ZrO2, Pr-CeO2 and the like. Rh supports are: alumina, ZrO2-Al2O3, La-ZrO2 and similar. The length of the entry zone top layer is about 25-75% of the total length of the substrate.

[0041] FIG. 13 is an exemplary catalyst composite having a palladium-containing intermediate layer between the bottom layer and the top layer. In this embodiment, Pd is provided in two layers to maximize the HC and NOx conversion efficiency at cold start. The Pd-containing bottom layer has the following characteristics: Pd is about 10-40% of the total Pd of the bottom layer, about 80-100% of the Pd is in an OSC; about 0-20% of Pd is on a refractory metal oxide support; the total reactive coating load is about 0.06-0.12 g/cm3 (1-2 g/in3); the OSC loading is about 80-100% of the total reactive coating; refractory metal oxide loading is about 0-20%; and the coating is substantially uniform. The Pd interlayer has the following characteristics: Pd is about 40-80% of the available Pd; about 100% of the amount of Pd is in refractory metal oxides; the total reactive coating load is about 0.03-0.12 g/cm3 (0.5-2 g/in3), preferably about 0.06-0.09 g/cm3 (1-1.5 g /in3); a layer substantially free of OSC; and the coating is substantially uniform. The uniform/homogeneous or zoned Pd/Rh top layer is designed as required to meet the needs of a particular application.

[0042] FIG. 14 is an exemplary catalyst composite having a palladium-containing zoned intermediate layer between the bottom layer and the top layer. The Pd-containing bottom layer has the following characteristics: Pd is about 10-40% of available Pd; about 80-100% of Pd is in an OSC; about 0-20% of Pd is in refractory metal oxides; the total reactive coating load is about 0.06-0.12 g/cm3 (1-2 g/in3); the OSC loading is about 80-100% of the total reactive coating; refractory metal oxide loading is about 0-20%; and the coating is substantially uniform. The zoned Pd-containing middle layer has the following characteristics: Pd is about 40-80% of the available Pd; about 100% of Pd is in refractory metal oxide; the total reactive coating load is about 0.03-0.12 g/cm3 (0.5-2 g/in3), preferably about 0.06-0.09 g/cm3 (1-1.5 g /in3); substantially OSC-free layer; the entrance zone has Pd in an amount of about 60-80% of the amount of Pd available to the intermediate layer and the exit zone has an amount of Pd of about 20-40% of the total amount of Pd available to the intermediate layer. middle layer.

[0043] FIGS. 15 and 16 are different views of a wall flow filter substrate 50 having a plurality of passages 52. The passages are tubularly enclosed by the inner walls 53 of the filter substrate. The substrate has an inlet end 54 and an outlet end 56. Alternating passages are plugged at the inlet end with inlet plugs 58 and at the outlet end with outlet plugs 60 to form opposing tray patterns at inlet 54 and outlet 56 A gas stream 62 enters through the unbuffered inlet channels 64, is stopped by the outlet plug 60 and diffuses through the channel walls 53 (which are porous) into the outlet channels 66. The gas cannot pass back into the inlet side of the walls due to inlet plugs 58.

[0044] In an exemplary embodiment, the input channels 64 have a layer containing Pd as the only PGM coated thereon. The Pd is supported on an OSC and/or a refractory metal oxide support. This layer can be homogeneous or zoned. The reactive coating load can be in the range of about 0.06-0.15 g/cm3 (1-2.5 g/in3). The OSC load can be about 50-80% of the total reactive coating load. The output channels 66 have a Pd/Rh layer (homogeneous or zoned) with a reactive coating loading in the range of about 0.03-0.09 g/cm3 (0.5-1.5 g/in3) . Layer compositions and zoning configurations can be in accordance with any of the designs described here.

Components

[0045] TWC catalysts that exhibit good activity and longevity comprise one or more platinum group metals (e.g., platinum, palladium, rhodium, rhenium, and iridium) arranged on a high surface area refractory metal oxide component or support. , for example, a high surface area alumina. The support is coated on a suitable carrier or substrate such as a monolithic carrier comprising a refractory ceramic or metal honeycomb structure; or refractory particles such as spheres or short extruded segments of a suitable refractory material. Refractory metal oxide components or supports may be stabilized against thermal degradation by materials such as zirconia, titania, alkaline earth metal oxides such as baria, calcium or strontia or, more usually, rare earth metal oxides, e.g. ceria, lantana and mixtures of two or more rare earth metal oxides. For example, see Pat. U.S. No. 4,171,288 (Keith), which is incorporated herein by reference in its entirety. TWC catalysts can be formulated to include an oxygen storage component (OSC) (e.g., ceria and/or praseodymia).

[0046] High surface refractory metal oxide components or supports refers to support particles larger than 20 Å and a wide distribution of pores. High surface refractory metal oxide supports, e.g., alumina support materials, also referred to as “gamma alumina” or “activated alumina,” typically exhibit a BET surface area in excess of 60 square meters per gram (“m2 /g”), often up to about 200 m2/g or higher. Such activated alumina is usually a mixture of gamma and delta alumina phases, but may also contain substantial amounts of eta, kappa and theta alumina phases. Refractory metal oxides other than activated alumina can also be used as supports for at least some catalytic components in a given catalyst. For example, raw ceria, zirconia, alpha alumina and other materials are known for such use. Although many of these materials suffer from the disadvantage of having a considerably lower BET surface area than activated alumina, this disadvantage tends to be compensated by a greater durability of the resulting catalyst.

[0047] The catalytic layer of the composites described here may also contain stabilizers and promoters, as desired. Suitable stabilizers include one or more non-reducible metal oxides in which the metal is selected from the group consisting of barium, calcium, magnesium, strontium and mixtures thereof. Preferably, the stabilizer, where present, comprises one or more barium and/or strontium oxides. Suitable promoters include one or more non-reducible oxides of one or more rare earth metals selected from the group consisting of lanthanum, praseodymium, yttrium, zirconium and mixtures thereof.

Carrier

[0048] In one or more embodiments, one or more catalyst compositions are disposed on a carrier. The carrier may be any of those materials typically used to prepare catalysts and will preferably comprise a ceramic or metal honeycomb structure. Any suitable carrier may be employed, such as a monolithic substrate of the type that has thin, parallel gas flow passages that extend across an inlet or outlet face of the substrate, so that the passages are open for fluid flow therein. (referred to as alveolar throughflow substrates). The passages, which are essentially straight pathways from their fluid inlet to their fluid outlet, are defined by walls on which the catalytic material is coated as a reactive coating so that gases flowing through the passages come into contact with the catalytic material. . The flow passages of the monolithic substrate are thin-walled channels, which can be of any shape and cross-sectional size such as trapezoidal, rectangular, square, sinusoidal, hexagonal, oval, circular, etc. Such structures may contain from about 60 to about 900 or more gas inlet openings (i.e., cells) per square inch of cross section.

[0049] The carrier may also be a wall flow filter substrate, where the channels are alternately blocked, allowing a gaseous stream to enter the channels from one direction (input direction), to flow through the channel walls and exit channels in the other direction (output direction). A dual oxidation catalyst composition may be coated on the wall flow filter. If such a carrier is used, the resulting system will be capable of removing particulate matter along with gaseous pollutants. The wall flow filter carrier may be made from materials commonly known in the art, such as cordierite or silicon carbide.

[0050] Ceramic carriers can be made from any suitable refractory material, for example, cordierite, cordierite-alumina, silicon nitride, zircon mullite, spodumene, alumina-silica magnesia, zircon silicate, sillimanite, a magnesium silicate, zircon , petalite, alumina, an aluminosilicate and the like.

[0051] Carriers usable for the catalysts of the present invention may also be metallic in nature and be composed of one or more metals or metal alloys. Metal carriers can be used in various formats such as corrugated sheets or monolithic form. Preferred metal supports include heat-resistant metals and metal alloys such as titanium and stainless steel, as well as other alloys in which iron is a substantial or major component. Such alloys may contain one or more nickel, chromium and/or aluminum and the total amount of these metals may advantageously comprise at least about 15% by weight of the alloy, for example about 10-25% by weight chromium, about from 3-8% by weight of aluminum and up to about 20% by weight of nickel. Alloys may also contain small amounts or traces of one or more other metals such as manganese, copper, vanadium, titanium and the like. The surface of metal carriers can be oxidized at elevated temperatures, for example about 1000 °C and higher, to improve the corrosion resistance of the alloys by forming an oxide layer on the surfaces of the carriers. Such elevated temperature-induced oxidation can intensify the adhesion of the refractory metal oxide support and catalytically promote metal component to the carrier.

[0052] When describing the amount of reactive coating or catalytic metal components or other components of the composition, it is convenient to use units of component weight per unit volume of catalyst substrate. Therefore, the units, grams per cubic centimeter (“g/cm3”) (grams per cubic inch (“g/in3”)) and grams per cubic meter (“g/m3”) (grams per cubic foot (“g/ ft3”)) are used here to mean the weight of a component per volume of the substrate, including the volume of substrate voids. Other units of weight per volume such as g/L are also sometimes used. The total loading of the catalyst composition in the carrier, such as a monolithic through flow carrier, is typically about 0.03 to about 0.36 g/cm3 (0.5 to about 6 g/in3) and more. typically from about 0.06 to about 0.30 g/cm3 (1 to about 5 g/in3). The total charge of the PGM component without support material (e.g., Pd alone or in combination with Rh) is typically in the range of about 1059.44 to about 7062.93 g/m3 (30 to about 200 g/ft3 ) for each individual carrier.

[0053] In alternative embodiments, one or more catalyst compositions can be deposited on an open-cell foam substrate. Such substrates are well known in the art and are typically formed from ceramic or metallic refractory materials.

Modalities

[0054] Various embodiments are listed below. It will be understood that the embodiments listed below may be combined with all aspects and other embodiments in accordance with the scope of the invention.

[0055] Embodiment 1. An automotive catalyst composite comprising: a catalytic material on a carrier, the catalytic material comprising at least two layers: a first layer deposited directly on the carrier comprising a first palladium component supported on a first metal oxide component refractory, a first oxygen storage component, or a combination thereof; and a second layer deposited on top of the first layer comprising a rhodium component supported on a second refractory metal oxide component and a second palladium component supported on a second oxygen storage component, a third refractory metal oxide component, or a combination thereof, wherein the catalytic material is effective for three-way conversion (TWC).

[0056] Modality 2. The automotive catalyst composite of modality 1, in which the first layer is substantially free of any other platinum group metals.

[0057] Modality 3. The automotive catalyst composite of modality 1 or 2, in which the first layer additionally comprises barium oxide, strontium oxide, or combinations thereof.

[0058] Embodiment 4. The automotive catalyst composite of any of embodiments 1 to 3, in which the first layer comprises about 40-95% (or even about 65-90%) by weight of the total palladium content of the composite and the second layer comprises about 5-60% (or even about 10-35%) by weight of the total palladium content of the composite.

[0059] Embodiment 5. The automotive catalyst composite of any one of embodiments 1 to 4, in which the weight ratio of the palladium component to the rhodium component in the second layer is about 0.1:1 to about 20: 1 (or about 0.5:1 to about 10:1, or even about 1:1 to about 5:1).

[0060] Embodiment 6. The automotive catalyst composite of any of embodiments 1 to 5, in which the first palladium component is supported by a combination of the first refractory metal oxide component and the first oxygen storage component, in which the first refractory metal oxide component comprises a stabilized alumina and the first oxygen storage component comprises about 25-50% by weight of ceria based on the total weight of the first oxygen storage component.

[0061] Embodiment 7. The automotive catalyst composite of embodiment 6, in which the stabilized alumina of the first refractory metal oxide component is selected from the group consisting of activated alumina, lantana-alumina, baria-alumina, ceria-alumina, ceria-lantana-alumina, zirconia-alumina, ceria-zirconia-alumina, or combinations thereof.

[0062] Embodiment 8. The automotive catalyst composite of any of embodiments 1 to 7, in which the second refractory metal oxide component comprises an alumina-based support, a zirconia-based support, or combinations thereof.

[0063] Embodiment 9. The automotive catalyst composite of any one of embodiments 1 to 8, in which the alumina-based support comprises an activated alumina compound selected from the group consisting of alumina, stabilized zirconia-alumina, lantana-alumina , baria-alumina, ceria-alumina, zirconia-alumina, ceria-zirconia-alumina, lantana-zirconia-alumina, baria-lantana-alumina, baria-lantana-neodymia alumina and combinations thereof.

[0064] Embodiment 10. The automotive catalyst composite of any one of embodiments 1 to 9, in which the second refractory metal oxide component comprises about 20% by weight of stabilized zirconia-alumina based on the total weight of the second refractory metal oxide component. refractory metal oxide.

[0065] Embodiment 11. The automotive catalyst composite of any one of embodiments 1 to 10, in which the second refractory metal oxide component comprises a zirconia-based support selected from the group consisting of zirconia, lantana-zirconia, titania - zirconia, titania-lantana-zirconia and combinations thereof.

[0066] Embodiment 12. The automotive catalyst composite of any one of embodiments 1 to 11, in which the second oxygen storage component comprises a ceria-zirconia composite comprising about 10-50% by weight of ceria based on weight total of the second oxygen storage component.

[0067] Embodiment 13. The automotive catalyst composite of any of embodiments 1 to 12, in which the second palladium component is supported on the third refractory metal oxide component comprising alumina, stabilized alumina, praseodymium-zirconia, or combinations thereof .

[0068] Embodiment 14. The automotive catalyst composite of any one of embodiments 1 to 13, in which the first layer comprises, in percentage by weight of the first layer: the first refractory metal oxide component in an amount of about 5095% (or even about 20-80%); the first oxygen storage component comprising a first ceria-zirconia composite in an amount of about 20-80%; and at least one promoter or stabilizer selected from lantana, baria, zirconia and strontium in an amount of up to about 10% (or even about 0.1-10%, or about 0.1-5%); wherein the first ceria-zirconia composite comprises ceria in an amount of about 25-50% by weight of the first ceria-zirconia composite.

[0069] Embodiment 15. The automotive catalyst composite of any one of embodiments 1 to 14, in which the second layer comprises, in percentage by weight of the second layer: the second refractory metal oxide component in an amount of about 5080% ; and the second oxygen storage component comprising a second ceria-zirconia composite or the third refractory metal oxide component in an amount of about 2050%; at least one promoter or stabilizer selected from lantana, baria, zirconia and strontium in an amount of up to about 10% (or even about 0.1-10%, or about 0.1-5%); wherein the second ceria-zirconia composite comprises ceria in an amount of 10-50% by weight of the second ceria-zirconia composite.

[0070] Embodiment 16. The automotive catalyst composite of any of embodiments 1 to 15, in which 20-60% of the total palladium content of the first layer is supported on the first refractory metal oxide component and about 40-80% of the total palladium content of the first layer is supported on the first oxygen storage component.

[0071] Embodiment 17. The automotive catalyst composite of any one of embodiments 1 to 16, in which the palladium content in the first oxygen storage component is about 0.5-3% by weight of the first oxygen storage component and wherein the first layer optionally further comprises palladium in the first refractory metal oxide component.

[0072] Embodiment 18. The automotive catalyst composite of any one of embodiments 1 to 17, in which the second layer additionally comprises a platinum component in an amount of about 3.53 to 353.15 g/m3 (0.1 at 10 g/ft3).

[0073] Embodiment 19. The automotive catalyst composite of any one of embodiments 1 to 18 further comprising a base layer between the carrier and the first layer, wherein the base layer is substantially free of any platinum group metals and comprises alumina.

[0074] Embodiment 20. The automotive catalyst composite of any one of embodiments 1 to 19, in which the carrier is a through-flow substrate or a wall-flow filter.

[0075] Modality 21. The automotive catalytic composite of any one of modalities 1 to 20, in which the first layer is zoned.

[0076] Embodiment 22. The automotive catalyst composite of any of embodiments 1 to 21, in which the second layer is zoned.

[0077] Embodiment 23. The automotive catalyst composite of any one of embodiments 1 to 22, in which a first layer charge is in the range of about 0.09-0.24 g/cm3 (1.5-4.0 g/in3) and a loading of the second layer is in the range of about 0.04-0.12 g/cm3 (0.75-2.0 g/in3).

[0078] Embodiment 24. The automotive catalyst composite of any one of embodiments 1 to 23 further comprising a palladium-containing intermediate layer between the first layer and the second layer, wherein the first layer comprises the palladium component supported on the first storage component of oxygen and the intermediate layer comprises a palladium component supported on a fourth refractory metal oxide component and is substantially free of an oxygen storage component.

[0079] Embodiment 25. The automotive catalyst composite of embodiment 20, in which the first layer is deposited in the inlet channels of a wall flow filter and the second layer is deposited in the outlet channels of the wall flow filter.

[0080] Embodiment 26. An exhaust gas treatment system comprising the catalyst composite of any one of embodiments 1 to 25 located downstream of a gasoline engine.

[0081] Embodiment 27. The exhaust gas treatment system of embodiment 26, in which the automotive catalyst composite is located downstream of a gasoline engine in a closely coupled position, in a position downstream of the closely coupled position, or both.

[0082] Embodiment 28. A method for treating an exhaust gas comprising hydrocarbons, carbon monoxide and nitrogen oxides comprising: contacting the exhaust gas with the automotive catalyst composite of any of embodiments 1 to 25.

[0083] Embodiment 29. Composite automotive catalysts, exhaust gas treatment systems, or method of any of embodiments 1 to 28, in which the catalytic material is substantially effective to simultaneously oxidize carbon monoxide and hydrocarbons and reduce carbon oxide. nitrogen.

EXAMPLES

[0084] The following non-limiting examples will serve to illustrate the various embodiments of the present invention.

EXAMPLE 1

[0085] A catalyst composite was prepared comprising a two-layer catalyst having palladium (Pd) as the only PGM in a first layer (i.e. bottom coating) and a combination of palladium (Pd) and rhodium (Rh) in a second layer (i.e. top coat). A schematic representation of this catalyst composite is provided in FIG. 1. The first layer (i.e., bottom coat) was prepared by separately impregnating Pd onto a stabilized alumina (i.e., first support) and impregnating Pd onto an oxygen storage component (OSC) (i.e., second support). The first impregnated support was prepared by incipient impregnation of a palladium nitrate solution, diluted to minimize metal concentration, onto 0.03 g/cm3 (0.6 g/in3) of a La-gamma-alumina of area raised surface resulting in 2429 g/m3 (68.8 g/ft3) of Pd. The second impregnated support was prepared by adding a palladium nitrate solution, diluted to minimize the metal concentration, to 0.09 g/cm3 (1.50 g/in3) of a ceria-zirconia composite (CeO2: 40 % by weight) resulting in 1457.78 g/m3 (41.28 g/ft3) of Pd. The two impregnated support powders were individually heat-fixed at 550 °C and milled. A single aqueous reactive coating was formed by dispersing the heat-fixed impregnated supports in water and acid (e.g., nitric acid or acetic acid). Furthermore, Ba and Zr metal promoters were dispersed in it. The remaining 971.15 g/m3 (27.5 g/ft3) of Pd (from Pd nitrate) was added directly into the finished slurry. The slurry was then coated onto a monolith at a load of 0.14 g/cm3 (2.38 g/in3), dried at 110°C in air and calcined at 550°C in air.

[0086] The second layer (i.e., top coat) was prepared by incipient impregnation of a solution of Rh nitrate and Nd nitrate, diluted to minimize the metal concentration, about 0.06 g/cm3 (1.0 g/in3) of high surface area La-ZrO2-gamma-alumina resulting in 349.61 g/m3 (9.9 g/ft3) of Rh and 1.52 x 103 g/cm3 (0.025 g/in3) of Nd2O3. Rd and Nd were chemically fixed on the alumina surface. A first slurry was made from Rh/Nd/La-ZrO2-Al2O3 (i.e., first support) and milled to particle size distribution 90% smaller than 16-18 μm. The second support was prepared by impregnating a Pd nitrate solution, diluted to minimize metal concentration, onto 0.01 g/cm3 (0.25 g/in3) of a ceria-zirconia composite (CeO2: 40% by weight ) resulting in 254.27 g/m3 (7.2 g/ft3) of Pd. The impregnated support powder was dried at 110°C and calcined at 550°C for 2 hours. The calcined support powder was made into a second slurry and milled to particle size distribution 90% smaller than 16-18 μm. The two slurries were mixed together. Zirconium nitrate and an alumina binder were added to the mixed slurry, which was then coated onto a monolith at a load of 0.08 g/cm3 (1.4 g/in3), dried at 110 °C in air and calcined. at 550 °C in air. The total reactive coating load after calcination was 0.22 g/cm3 (3.7 g/in3).

EXAMPLE 2 COMPARATIVE

[0087] A comparative catalyst composite comprised of a two-layer catalyst having palladium (Pd) as the only PGM in a first layer (i.e. bottom coating) and rhodium (Rh) as the only PGM in a second layer (i.e. is, top coating). A schematic representation of this catalyst composite is provided in FIG. 2. The first layer (i.e., bottom coat) was prepared by separately impregnating Pd onto stabilized alumina (i.e., first support) and impregnating Pd onto an oxygen storage component (OSC) (i.e., second support). The first impregnated support was prepared by incipient impregnation of a solution of Pd and Nd nitrate, diluted to minimize the metal concentration, onto 0.04 g/cm3 (0.75 g/in3) of La-gamma-alumina of area of high surface resulting in 3072.38 g/m3 (87 g/ft3) of Pd and 1.52 x 103 g/cm3 (0.025 g/in3) of Nd2O3. The second impregnated support was prepared by adding a palladium nitrate solution, diluted to minimize the metal concentration, to 0.08 g/cm3 (1.30 g/in3) of a ceria-zirconia composite (CeO2: 40 % by weight) resulting in 1532.66 g/m3 (43.4 g/ft3) of Pd. The two impregnated support powders were individually heat-fixed at 550 °C and milled. A single aqueous reactive coating was formed by the thermally fixed impregnated supports dispersed in water and acid (e.g., nitric acid or acetic acid). Furthermore, metal promoters Ba, Nd and Zr were dispersed in it. The remaining 14.5 g/ft3 of Pd (from Pd nitrate) was added into the finished slurry. The slurry was then coated onto a monolith at a load of 0.14 g/cm3 (2.38 g/in3), dried at 110°C in air and calcined at 550°C in air.

[0088] The second layer (i.e., top coat) was prepared by adding a solution of Rh nitrate and Rd nitrate to a slurry at pH 11 in 0.048 g/cm3 (0.8 g/in3) of High surface area la-zirconia-alumina resulting in 243.67 g/m3 (6.9 g/ft3) of Rh and 1.52 x 103 g/cm3 (0.025 g/in3) of Nd2O3. The second impregnated support was prepared by adding a solution of Rh nitrate, diluted to minimize the metal concentration, to 0.02 g/cm3 (0.30 g/in3) of a ceria-zirconia composite (CeO2: 40 % by weight) resulting in 70.63 g/m3 (2 g/ft3) of Rh. The two resulting slurries were milled separately to 90% particle size distribution between 16 -18 μm. Zirconium nitrate and 35.31 g/m3 (1 g/ft3) of Rh were added to the slurry to reduce the pH to about 4.5-5 of the final slurry. The impregnated support powders were individually chemically fixed at 550 °C and milled. The slurry was then coated onto a monolith at a load of 0.07 g/cm3 (1.18 g/in3), dried at 110°C in air and calcined at 550°C in air. The total reactive coating load after calcination was 0.21 g/cm3 (3.56 g/in3).

EXAMPLE 3 TEST

[0089] The composites of example 1 and comparative example 2 were aged for 50 hours at a maximum of 950 °C under fuel cut conditions in the engine. After aging, the catalysts were tested in the vehicle using the EPA FTP-75 protocol. The performance of such samples was evaluated by measuring the total cumulative emissions of hydrocarbons (HC) and NOx in the medium bed where there was no difference between the two samples in HC performance and there was an advantage for example 1 in NOx performance. data were as follows:

EXAMPLE 4

[0090] A catalyst composite was prepared comprising a two-layer catalyst having palladium (Pd) as the only PGM in a first layer (i.e. bottom coating) and a combination of palladium (Pd) and rhodium (Rh) in a second layer (i.e. top coat). A schematic representation of this catalyst composite is provided in FIG. 3. The first layer (i.e., bottom coat) was prepared by separately impregnating Pd onto stabilized alumina (i.e., first support) and impregnating Pd onto an oxygen storage component (OSC) (i.e., second support). The first impregnated support was prepared by incipient impregnation of a palladium nitrate solution, diluted to minimize metal concentration, onto 0.04 g/cm3 (0.60 g/in3) of a La-gamma-alumina of area raised surface resulting in 2083.57 g/m3 (59 g/ft3) of Pd. The second impregnated support was prepared by adding a palladium nitrate solution, diluted to minimize the metal concentration, to 0.09 g/cm3 (1.50 g/in3) of a ceria-zirconia composite (CeO2: 45 % by weight) resulting in 1836.36 g/m3 (52 g/ft3) of Pd. The two impregnated support powders were individually heat-fixed at 550 °C and milled. A single aqueous reactive coating was formed by dispersing the heat-fixed impregnated supports in water and acid (e.g., nitric acid or acetic acid). Furthermore, Ba metal promoters were dispersed in it. The remaining 688.63 g/m3 (19.5 g/ft3) of Pd (from Pd nitrate) was added directly into the finished slurry. An alumina binder was added to the slurry, which was then coated onto a monolith at a load of 0.14 g/cm3 (2.38 g/in3), dried at 110°C in air and calcined at 550°C in air.

[0091] The second layer (i.e., top coat) was prepared by incipient impregnation of a solution of Rh nitrate and Nd nitrate, diluted to minimize metal concentration, about 3.5 x 103 g/cm3 (0 .5 g/in3) of high surface area La-ZrO2-gamma-alumina and 3.5 x 103 g/cm3 (0.5 g/in3) of La-ZrO2 resulting in 349.61 g/m3 (9 .9 g/ft3) of Rh and 1.52 x 103 g/cm3 (0.025 g/in3) of Nd2O3. Rd and Nd were chemically fixed on the alumina surface. A slurry was made from Rh/Nd/(La-ZrO2-Al2O3 + La-ZrO2) (i.e., first support) and milled to particle size distribution 90% smaller than 16-18 μm. The second support was prepared by impregnating a Pd nitrate solution, diluted to minimize metal concentration, onto 0.01 g/cm3 (0.25 g/in3) of a ceria-zirconia composite (CeO2: 45% by weight ) resulting in 512.06 g/m3 (14.5 g/ft3) of Pd. The impregnated support powder was dried at 110°C and calcined at 550°C for 2 hours. The calcined support powder was then slurried and milled to particle size distribution 90% smaller than 16-18 μm. The two slurries were mixed together. An alumina binder was added to the slurry, which was then coated onto a monolith at a load of 0.08 g/cm3 (1.3 g/in3), dried at 110 °C in air and calcined at 550 °C in air. The total reactive coating load after calcination was 0.22 g/cm3 (3.7 g/in3).

EXAMPLE 5 COMPARATIVE

[0092] A comparative catalyst composite comprised of a two-layer catalyst having palladium (Pd) as the only PGM in a first layer (i.e. bottom coating) and rhodium (Rh) as the only PGM in a second layer (i.e. is, top coating). A schematic representation of this catalyst composite is provided in FIG. 4. The first layer (i.e., bottom coat) was prepared by separately impregnating Pd onto stabilized alumina (i.e., first support) and impregnating Pd onto an oxygen storage component (OSC) (i.e., second support). The first impregnated support was prepared by incipient impregnation of a palladium nitrate solution, diluted to minimize metal concentration, onto 0.04 g/cm3 (0.60 g/in3) surface area La-gamma alumina. high resulting in 2295.45 g/m3 (65 g/ft3) of Pd. The second impregnated support was prepared by adding a palladium nitrate solution, diluted to minimize the metal concentration, to 0.09 g/cm3 (1.50 g/in3) of a ceria-zirconia composite (CeO2: 45 % by weight) resulting in 2048.25 g/m3 (58 g/ft3) of Pd. The two impregnated support powders were individually heat-fixed at 550 °C and milled. A single aqueous reactive coating was formed by dispersing the heat-fixed impregnated supports in water and acid (e.g., nitric acid or acetic acid). Furthermore, Ba metal promoters were dispersed therein. The remaining 766.32 g/m3 (21.7 g/ft3) of Pd (from Pd nitrate) was added into the finished slurry. An alumina binder was added to the slurry, which was then coated onto a monolith at a load of 0.14 g/cm3 (2.38 g/in3), dried at 110°C in air and calcined at 550°C in air.

[0093] The second layer (i.e. top coat) was prepared by incipient impregnation of a solution of Rh nitrate and Nd nitrate, diluted to minimize metal concentration, about 0.03 g/cm3 (0.5 g/in3) of high surface area La-ZrO2-gamma-alumina and 0.03 g/cm3 (0.5 g/in3) of La-ZrO2 resulting in 261.32 g/m3 (7.4 g/ ft3) of Rh and 1.52 x 103 g/cm3 (0.025 g/in3) of Nd2O3. Rd and Nd were chemically fixed on the alumina surface. A first slurry was made from Rh/Nd/(La-ZrO2-Al2O3 + La-ZrO2) and milled to a 90% particle size distribution of less than 16-18 μm. The second support was prepared by impregnating a solution of Rh nitrate, diluted to minimize the metal concentration, onto 0.01 g/cm3 (0.25 g/in3) of a ceria-zirconia composite (CeO2: 45% by weight ) resulting in 88.29 g/m3 (2.5 g/ft3) of Rh. Rh was chemically fixed on the alumina surface. A second slurry was made from Rh/ceria-zirconia and milled to a particle size distribution 90% smaller than 16-18 μm. The two slurries were mixed together. An alumina binder was added to the mixed slurry, which was then coated onto a monolith at a load of 0.08 g/cm3 (1.3 g/in3), dried at 110 °C in air and calcined at 550 °C in air. The total reactive coating load after calcination was 0.22 g/cm3 (3.7 g/in3).

EXAMPLE 6 TEST

[0094] The composites of example 3 and comparative example 4 were aged for 50 hours at a maximum of 950 °C under fuel cut conditions in the engine. After aging, the catalysts were tested in the vehicle using the EPA FTP-75 protocol. The performance of such samples was evaluated by measuring the total cumulative emissions of hydrocarbons (HC) and NOx in the middle bed where there was no difference between the two samples in NOx performance and there was an advantage for example 4 in HC performance. The data were as follows:

EXAMPLE 7

[0095] A catalyst composite was prepared comprising a two-layer catalyst having palladium (Pd) as the only PGM in a first layer (i.e. bottom coating) and a combination of palladium (Pd) and rhodium (Rh) in a second layer (i.e. top coat). A schematic representation of this catalyst composite is provided in FIG. 5. The first layer (i.e., bottom coat) was prepared by impregnating Pd onto a high surface area stabilized alumina (i.e., first support) and combining Pd and OSC (i.e., second support) into a separate slurry . The first impregnated support was prepared by incipient impregnation of a palladium nitrate solution, diluted to minimize metal concentration, onto 0.04 g/cm3 (0.60 g/in3) Ba-gamma-alumina surface area. high, resulting in 1695.1 g/m3 (48 g/ft3) of Pd. The resulting impregnated powder was thermally fixed at 550 °C, transformed into a first slurry and milled. The second slurry was prepared by adding Pd nitrate solution, diluted to minimize metal concentration, to a slurry comprising 0.07 g/cm3 (1.25 g/in3) of ceria-zirconia composite ( CeO2: 40% by weight) at pH > 10, resulting in 423.78 g/m3 (12 g/ft3) of Pd. The resulting slurry was milled. A single aqueous reactive coating was formed by combining the first slurry of heat-fixed impregnated carrier in water and acid (e.g., nitric acid or acetic acid) with the second slurry. Furthermore, Ba metal promoters were dispersed in it. An alumina binder was added to the mixed slurry, which was then coated onto a monolith at a loading of 0.129 g/cm3 (2.115 g/in3), dried at 110 °C in air, and calcined at 550 °C in air.

[0096] The second layer (i.e. top coat) was prepared by incipient impregnation of a Pd nitrate solution, diluted to minimize the metal concentration, about 0.01 g/cm3 (0.25 g/in3) of La-gamma- high surface area alumina resulting in 353.15 g/m3 (10.0 g/ft3) of Pd. The resulting impregnated support powder was thermally fixed at 550 ° C, made into a first slurry and milled. Rh was chemically fixed onto a high surface area La-ZrO2-gamma-alumina and an OSC. A second slurry was made comprising 0.03 g/cm3 (0.6 g/in3) of high surface area La-ZrO2-gamma-alumina and 0.02 g/cm3 (0.35 g/in3) of ceria-zirconia composite (CeO2: 40% by weight), to which a Rh nitrate solution, diluted to minimize metal concentration, was added to pH 9. The resulting second slurry was ground. Furthermore, a Ba metal-containing promoter was dispersed in it. The two slurries were mixed together. An alumina binder was added to the mixed slurry, which was then coated onto a monolith at a loading of 0.084 g/cm3 (1.383 g/in3), dried at 110 °C in air and calcined at 550 °C in air. The total reactive coating load after calcination was 0.213 g/cm3 (3.497 g/in3).

EXAMPLE 8 COMPARATIVE

[0097] A comparative catalyst composite comprised of a two-layer catalyst having Rh as the only PGM in a first layer (i.e., bottom coating) and Pd as the only PGM in a second layer (i.e., top coating) . A schematic representation of this catalyst composite is provided in FIG. 6. The first layer (i.e. bottom coat) was prepared by impregnating a solution of Rh nitrate, diluted to minimize metal concentration, over 0.04 g/cm3 (0.75 g/in3) of La-ZrO2 -high surface area gamma alumina and 0.06 g/cm3 (1.0 g/in3) OSC (CeO2: 40% by weight), resulting in 105.94 g/m3 (3 g/ft3) of Rh. The resulting impregnated support powder was made into a slurry by dispersing in water containing monoethanolamine at pH 8. The slurry was milled. A single aqueous reactive coating was formed by combining the slurry with water and acid (e.g., nitric acid or acetic acid). An alumina binder was added to the slurry, which was then coated onto a monolith at a loading of 0.111 g/cm3 (1.827 g/in3), dried at 110 °C in air and calcined at 550 °C in air.

[0098] The second layer (i.e., top coat) was prepared by impregnating Pd onto high surface area Ba-gamma-alumina (i.e., first support) and combining Pd and an OSC (i.e., second support) in a separate slurry. The first impregnated support was prepared by incipient impregnation of a Pd nitrate solution, diluted to minimize metal concentration, onto 0.07 g/cm3 (1.25 g/in3) surface area Ba-gamma-alumina. high, resulting in 1854.02 g/m3 (52.5 g/ft3) of Pd. The resulting impregnated support powder was thermally fixed at 550 ° C, made into a first slurry and milled. The second slurry was prepared by adding a Pd nitrate solution, diluted to minimize metal concentration, to a slurry comprising 0.03 g/cm3 (0.5 g/in3) OSC (CeO2: 40 % by weight) at pH 9, resulting in 618 g/m3 (17.5 g/ft3) of Pd. Furthermore, a Ba metal-containing promoter was dispersed in it. The resulting second slurry was milled. The two slurries were mixed together with water and acid (e.g., nitric acid or acetic acid) forming a single aqueous reactive coating. An alumina binder was added to the mixed slurry, which was then coated onto a monolith at a loading of 0.114 g/cm3 (1.876 g/in3), dried at 110 °C in air and calcined at 550 °C in air. The total reactive coating load after calcination was 0.225 g/cm3 (3.703 g/in3).

EXAMPLE 9 COMPARATIVE

[0099] A comparative catalyst composite comprised of a two-layer catalyst having Pd as the only PGM in a first layer (i.e., bottom coating) and Rh as the only PGM in a second layer (i.e., top coating) . A schematic representation of this catalyst composite is provided in FIG. 7. The first layer was prepared by adding a Pd nitrate solution, diluted to minimize metal concentration, to 0.04 g/cm3 (0.60 g/in3) surface area La-gamma-alumina high and 0.07 g/cm3 (1.25 g/in3) of OSC (CeO2: 40% by weight) at pH 9, resulting in 2472.03 g/m3 (70.0 g/ft3) of Pd. Furthermore, a Ba metal-containing promoter was dispersed in it. The resulting slurry was milled. A single aqueous reactive coating was formed by combining the slurry with water and acid (e.g., nitric acid or acetic acid). Furthermore, a prosecutor from La was dispersed there. An alumina binder was added to the slurry, which was then coated onto a monolith at a load of 0.126 g/cm3 (2.076 g/in3), dried at 110 °C in air and calcined at 550 °C in air.

[00100] The second layer was prepared by adding a solution of Rh nitrate, diluted to minimize metal concentration, to a slurry comprising 0.04 g/cm3 (0.60 g/in3) of La-ZrO2 -gamma- high surface area alumina and 0.02 g/cm3 (0.35 g/in3) OSC (CeO2: 40% by weight) at pH 9, resulting in 105.94 g/m3 (3.0 g/ft3) of Rh. The resulting slurry was milled. A single aqueous reactive coating was formed by combining the slurry with water and acid (e.g., nitric acid or acetic acid). Furthermore, a Ba metal-containing promoter was dispersed therein. An alumina binder was added to the slurry, which was then coated onto a monolith at a load of 0.062 g/cm3 (1.027 g/in3), dried at 110 °C in air and calcined at 550 °C in air. The total reactive coating load after calcination was 0.189 g/cm3 (3.102 g/in3).

EXAMPLE 10 TEST

[00101] The composites of example 7 and comparative examples 8 and 9 were aged for 130 hours at a maximum of 985 °C under exothermic conditions in the engine. After aging, the catalysts were tested in the vehicle using the EPA FTP-75 protocol. The performance of such samples was evaluated by measuring the total cumulative emissions of hydrocarbons (HC) and NOx in the middle bed where there was an advantage for example 7 in all emission performances. The data were as follows:

EXAMPLE 11

[00102] A composite catalyst for use in a closely coupled position (first position downstream of the gasoline engine) was prepared comprising a two-layer catalyst having palladium (Pd) as the only PGM in a first layer (i.e., coating of bottom) and a combination of palladium (Pd) and rhodium (Rh) in a second layer (i.e. top coat). A schematic representation of this catalyst composite is provided in FIG. 1. The first layer (i.e., bottom coat) was prepared by separately impregnating Pd onto a stabilized alumina (i.e., first support) and impregnating Pd onto an oxygen storage component (OSC) (i.e., second support). The first impregnated support was prepared by incipient impregnation of a palladium nitrate solution, diluted to minimize metal concentration, onto 0.03 g/cm3 (0.6 g/in3) of a La-gamma-alumina of area raised surface resulting in 2048.25 g/m3 (58 g/ft3) of Pd. The second impregnated support was prepared by adding a palladium nitrate solution, diluted to minimize the metal concentration, to 0.09 g/cm3 (1.50 g/in3) of a ceria-zirconia composite (CeO2: 40 % by weight) resulting in 988.81 g/m3 (28 g/ft3) of Pd. The two impregnated support powders were individually heat-fixed at 550 °C and milled. A single aqueous reactive coating was formed by dispersing the heat-fixed impregnated supports in water and acid (e.g., nitric acid or acetic acid). Furthermore, Ba and Zr metal promoters were dispersed in it. The slurry was then coated onto a monolith at a load of 0.14 g/cm3 (2.38 g/in3), dried at 110°C in air and calcined at 550°C in air.

[00103] The second layer (i.e. top coat) was prepared by incipient impregnation of a solution of Rh nitrate and Nd nitrate, diluted to minimize the metal concentration, about 0.06 g/cm3 (1.0 g/in3) of high surface area La-ZrO2-gamma-alumina resulting in 176.57 g/m3 (5 g/ft3) of Rh and 1.52 x 103 g/cm3 (0.025 g/in3) of Nd2O3 . Rd and Nd were chemically fixed on the alumina surface. A first slurry was made from Rh/Nd/La-ZrO2-Al2O3 (i.e., first support) and milled to particle size distribution 90% smaller than 12-14 μm. The second support was prepared by impregnating a Pd nitrate solution, diluted to minimize metal concentration, onto 0.01 g/cm3 (0.25 g/in3) of a ceria-zirconia composite (CeO2: 40% by weight ) resulting in 317.83 g/m3 (9 g/ft3) of Pd. The impregnated support powder was dried at 110°C and calcined at 550°C for 2 hours. The calcined support powder was made into a second slurry and milled to particle size distribution 90% smaller than 16-18 μm. The two slurries were mixed together. Zirconium nitrate and an alumina binder were added to the mixed slurry, which was then coated onto a monolith at a load of 0.08 g/cm3 (1.4 g/in3), dried at 110 °C in air and calcined. at 550 °C in air. The total reactive coating load after calcination was 0.22 g/cm3 (3.7 g/in3).

EXAMPLE 12 COMPARATIVE

[00104] A comparative catalyst composite for use in a position below the floor (second position downstream of the gasoline engine) was prepared comprising a two-layer catalyst having palladium (Pd) as the only PGM in a first layer (i.e. bottom coat) and rhodium (Rh) as the only PGM in a second layer (i.e. top coat). The first layer (i.e., bottom coat) was prepared by separately impregnating Pd onto stabilized alumina (i.e., first support) and impregnating Pd onto an oxygen storage component (OSC) (i.e., second support). The first impregnated support was prepared by incipient impregnation of a Pd nitrate solution, diluted to minimize metal concentration, onto 0.14 g/cm3 (2.35 g/in3) surface area La-gamma-alumina. high (52.97 g/m3 (1.5 g/ft3) of Pd). The second impregnated support was prepared by adding a palladium nitrate solution, diluted to minimize the metal concentration, to 0.03 g/cm3 (0.5 g/in3) of a ceria-zirconia composite (CeO2: 40 % by weight) resulting in a total of 635 g/m3 (18 g/ft3) of Pd. The two impregnated support powders were individually heat-fixed at 550 °C and milled. A single aqueous reactive coating was formed by dispersing the heat-fixed impregnated supports in water and acid (e.g., nitric acid or acetic acid). Furthermore, metal promoters Ba, Nd and Zr were dispersed in it. The remaining 512.06 g/m3 (14.5 g/ft3) of Pd (from Pd nitrate) was added directly into the mixed slurry. The slurry was then coated onto a monolith at a load of 0.14 g/cm3 (2.38 g/in3), dried at 110°C in air and calcined at 550°C in air.

[00105] The second layer (i.e., top coat) was prepared by adding a solution of Rh nitrate to two supports: 0.09 g/cm3 (1.5 g/in3) of La-zirconia-alumina of high surface area and 0.03 g/cm3 (0.50 g/in3) of a ceria-zirconia composite (CeO2: 10% by weight) resulting in 56.50 g/m3 (1.6 g/ft3) of Rh. The two impregnated supports were slurried and ground to 90% particle size distribution between 16 & 18 μm. The slurry was then coated onto a monolith at a load of 0.07 g/cm3 (1.18 g/in3), dried at 110°C in air and calcined at 550°C in air. The total reactive coating load after calcination was 0.21 g/cm3 (3.56 g/in3).

EXAMPLE 13

[00106] A composite catalyst for use in a position below the floor (second position downstream of the gasoline engine) was prepared comprising a two-layer catalyst having palladium (Pd) as the only PGM in a first layer (i.e. coating bottom layer) and a combination of palladium (Pd) and rhodium (Rh) in a second layer (i.e. top coat). A schematic representation of this catalyst composite is provided in FIG. 1. The preparation was according to example 11, to achieve about 565.03 g/m3 (16 g/ft3) of Pd in the base coat and 70.62 g/m3 (2 g/ft3) in the base coat. top and about 5.6 g/m3 (1.6 g/ft3) of Rh in the top coat.

EXAMPLE 14 TEST

[00107] A test system according to FIG. 8 was used with the aged engine of example 11 (1050 °C for 150 hours) in the first position and both comparative example 12 and example 13 in the second position. Before testing, the composites of comparative example 12 and Example 13 were aged in the engine (1080 ° C for 150 hours). After aging, the catalysts were tested in the vehicle using the EPA FTP-75 protocol. The performance of such samples was evaluated by measuring the total cumulative emissions of hydrocarbons (HC) and NOx in the medium bed where there was no difference between the two samples in HC performance and there was an advantage for example 1 in NOx performance.

[00108] The data was as follows:

[00109] From the EPA FTP-75 test a significant advantage for example 13 in non-methane HC (NMHC) and NOx performance. The data was as follows:

[00110] References throughout this application to "an embodiment", "certain embodiments", "one or more embodiments" or "an embodiment" mean that a particular aspect, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the appearance of phrases such as “in one or more embodiments”, “in certain embodiments”, “in an embodiment” or “in an embodiment” in various places throughout this application are not necessarily referring to the same embodiment of the invention. Furthermore, particular aspects, structures, materials, or characteristics may be combined in any appropriate manner in one or more embodiments.

[00111] The invention has been described with specific reference to the embodiments and modifications thereof described above. Additional modifications and changes may occur to others when reading and understanding the order. It is intended to include all such modifications and changes as they are within the scope of the invention.

Claims (23)

1. Automotive catalyst composite comprising: a catalytic material on a carrier, the catalytic material comprising at least two layers: a first layer deposited directly on the carrier comprising a first palladium component supported on each of the first refractory metal oxide component and a first oxygen storage component; and a second layer deposited on top of the first layer comprising a rhodium component supported on a second refractory metal oxide component and a second palladium component supported on a second oxygen storage component, a third refractory metal oxide component or a combination thereof, wherein the second refractory metal oxide component comprises a zirconia-stabilized alumina or a zirconia-based support selected from the group consisting of zirconia, lantana-zirconia, titania-zirconia, titania-lantana-zirconia and combinations thereof in which the catalytic material is effective to perform three-way conversion (TWC), characterized by the fact that the first layer comprises 40-95% by weight of the total palladium content of the composite and the second layer comprises 5 -60% by weight of the total palladium content of the composite, wherein the first refractory metal oxide component comprises a stabilized alumina and the first oxygen storage component comprises 25-50% by weight of ceria based on the total weight of the composite. first oxygen storage component. 2. Automotive catalyst composite according to claim 1, characterized in that the first layer is substantially free of any other platinum group metals. 3. Automotive catalyst composite according to claim 1, characterized in that the first layer additionally comprises barium oxide, strontium oxide or combinations thereof. 4. Automotive catalyst composite according to claim 1, characterized in that the weight ratio of the second palladium component to the rhodium component in the second layer is from 0.1:1 to 20:1. 5. Automotive catalytic composite according to claim 4, characterized in that the stabilized alumina of the first refractory metal oxide component is selected from the group consisting of activated alumina, lantana-alumina, baria-alumina, ceria-alumina, ceria-lantana-alumina, zirconia-alumina, ceria-zirconia-alumina and combinations thereof. 6. Automotive catalytic composite according to claim 1, characterized by the fact that the second refractory metal oxide component comprises 20% by weight of zirconia-stabilized alumina based on the total weight of the second refractory metal oxide component. 7. Automotive catalytic composite according to claim 1, characterized by the fact that the second oxygen storage component comprises a ceria-zirconia composite comprising 10-50% by weight of ceria based on the total weight of the second storage component of oxygen. 8. Automotive catalyst composite according to claim 1, characterized in that the second palladium component is supported on the third refractory metal oxide component comprising alumina, stabilized alumina, praseodymium-zirconia or combinations thereof. 9. Automotive catalyst composite according to claim 1, characterized in that the first layer comprises, in percentage by weight of the first layer: the first refractory metal oxide component in an amount of 50-95%; the first oxygen storage component comprising a first ceria-zirconia composite in an amount of 20-80%; and at least one promoter or stabilizer selected from lantana, baria, zirconia and strontium in an amount of up to 10%; wherein the first ceria-zirconia composite comprises ceria in an amount of 25-50% by weight based on the total weight of the first ceria-zirconia composite. 10. Automotive catalyst composite according to claim 1, characterized in that the second layer comprises, in percentage by weight of the second layer: the second refractory metal oxide component in an amount of 50-80%; the second oxygen storage component comprising a second ceria-zirconia composite or the third refractory metal oxide component in an amount of 20-50%; and at least one promoter or stabilizer selected from lantana, baria, zirconia and strontium in an amount of up to 10%; wherein the second ceria-zirconia composite, when present, comprises ceria in an amount of 10-50% by weight based on the total weight of the second ceria-zirconia composite. 11. Automotive catalyst composite according to claim 1, characterized by the fact that 20-60% of the total palladium content of the first layer is supported on the first refractory metal oxide component and 40-80% of the total palladium content of the first layer is supported on the first oxygen storage component. 12. Automotive catalyst composite according to claim 1, characterized in that the palladium content in the first oxygen storage component is 0.5-3% by weight of the first oxygen storage component and in which the first layer optionally further comprises palladium in the first refractory metal oxide component. 13. Automotive catalyst composite according to claim 1, characterized in that the second layer additionally comprises a platinum component in an amount in the range of 3.53 to 353.15 g/m3 (0.1 to 10 g/m3). ft3). 14. Automotive catalyst composite according to claim 1, characterized by the fact that it further comprises a base layer between the carrier and the first layer, wherein the base layer is substantially free of any platinum group metals and comprises alumina. 15. Automotive catalyst composite according to claim 1, characterized in that the carrier is a through-flow substrate or a wall-flow filter. 16. Automotive catalyst composite according to claim 1, characterized in that the first layer is zoned. 17. Automotive catalyst composite according to claim 1, characterized in that the second layer is zoned. 18. Automotive catalyst composite according to claim 1, characterized by the fact that the first layer has a charge in the range of 0.09-0.24 g/cm3 (1.5-4.0 g/in3) and the second layer has a charge in the range of 0.04-0.12 g/cm3 (0.75-2.0 g/in3). 19. Automotive catalyst composite according to claim 1, characterized in that it further comprises: a palladium-containing intermediate layer between the first layer and the second layer, wherein the first layer comprises the palladium component supported on the first storage component of oxygen; and the intermediate layer comprises a palladium component supported on a fourth refractory metal oxide component and is substantially free of an oxygen storage component. 20. Automotive catalyst composite according to claim 15, characterized in that the first layer is deposited in inlet channels of a wall flow filter and the second layer is deposited in outlet channels of the wall filter. 21. System for treating exhaust gas, characterized by the fact that it comprises the catalyst composite as defined in claim 1 located downstream of a gasoline engine. 22. The exhaust gas treatment system of claim 21, wherein the automotive catalyst composite is located downstream of a gasoline engine in a closely coupled position, in a position downstream of the closely coupled position, or both. 23. Method for treating exhaust gas comprising hydrocarbons, carbon monoxide and nitrogen oxides, characterized in that it comprises: bringing the exhaust gas into contact with the automotive catalyst composite as defined in claim 1.