WO2016185386A1

WO2016185386A1 - Rhodium-iron catalysts for twc converter systems

Info

Publication number: WO2016185386A1
Application number: PCT/IB2016/052877
Authority: WO
Inventors: Randal L. Hatfield; Stephen J. Golden; Johnny T. Ngo
Original assignee: Clean Diesel Technologies, Inc.
Priority date: 2015-05-18
Filing date: 2016-05-17
Publication date: 2016-11-24
Also published as: CN107921366A

Abstract

Close-coupled (CC) and underfloor (UF) three-way catalysts that are produced according to varied material compositions and catalyst configurations are disclosed. The CC and UF catalysts include Fe-activated Rh compositions that provide greater catalytic functionality. These CC and UF catalysts are incorporated within engine systems as components of TWC converters that are part of TWC systems for controlling and reducing engine exhaust emissions. The conversion performance of these TWC systems is assessed and compared employing U.S. Federal Test Procedure (FTP-75) and supplemental FTP US06 protocols within a turbo gasoline direct injection engine. These TWC systems exhibit improved catalytic performance when compared with the catalytic performance of a high PGM-based Original Equipment Manufacturer (OEM) catalyst employed in TWC applications.

Description

Rhodium-Iron Catalysts for TWC Converter Systems

BACKGROUND

Field of the Disclosure

The present disclosure relates generally to three-way catalytic (TWC) system applications, and more specifically, to TWC systems including Rh-Fe material compositions for the reduction of emissions from engine exhaust systems.

Background Information

Three-way catalytic (TWC) systems are located within the exhaust systems of internal combustion gas engines to promote the oxidation of unburned hydrocarbons (HC) and carbon monoxide (CO), and the reduction of nitrogen oxides (NOx) within the exhaust gas stream. The elevated cost of conventional TWC systems for controlling/reducing HC, CO and NOx emissions is primarily due to (a) the presence of complex groups of metal compounds within the catalyst systems and (b) the cost of obtaining said metals.

The catalysts within TWC systems typically contain platinum group metals (PGM), such as, for example platinum (Pt), palladium (Pd), and rhodium (Rh), amongst others. Pt and Pd are generally used for HC and CO conversion, while Rh is more effective for the reduction of NOx. Although the price of Rh tends to fluctuate, its greater performance in NOx conversion makes Rh the most common element employed within TWC systems.

Three factors influence the increased trend in consumption of PGM for automotive emission abatement. The first factor is the continuous increase in automobile production related to the increased portion of the world population demanding satisfaction of their personal transportation needs. The second factor is the tightening of the emissions standards around the world, as governments adopt more stringent NOx, hydrocarbon, and particulate emission regulations. This factor is confirmed by the recent modifications to vehicle emission standards in the United States with the strengthened Tier 3 emission standard from the U.S. Environmental Protection Agency (EPA) and the low emission vehicle (LEV III) program implemented by the California Air Resources Board. The third factor is the current drive for reduction of C0₂ emissions, which will direct automakers to adopt engine technologies that reduce the engine exhaust temperature due to improved engine thermal efficiencies.

As the supply of PGM is limited, an increase in demand may lead to supply interruptions and excessively high pricing for the PGM and the technologies that rely on their unique properties. Accordingly, there is a continuing need to provide TWC systems in which the catalytic performance per unit mass of PGM be maximized and enabled to provide improved conversion levels so that the emission limits can be achieved cost- effectively.

SUMMARY

The present disclosure describes close-coupled (CC) and underfloor (UF) three- way catalysts that are produced according to varied material compositions and catalyst configurations. In some embodiments, a PGM composition includes platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), and rhodium (Rh), either by themselves, or in combinations thereof employing different loadings. In an example, the PGM composition includes Pd loadings within a range from about 10 g/ft³ to about 100 g/ft³, alone or in combination with Ba loadings. In another example, the PGM composition includes Rh loadings within a range from about 1 g/ft³ to about 10 g/ft³, alone or activated

In some embodiments, a variety of TWC systems are configured to assess their catalytic performance by measuring mid-bed and tailpipe emissions according to the U.S. Federal Test Procedure (FTP-75) and U.S. Supplemental FTP US06 (SFTP-US06) testing protocols. In these embodiments, the TWC systems are configured to include CC and UF catalysts or a CC catalyst only. Further to these embodiments, the configured TWC systems are mechanically coupled to and in fluidic communication with an internal combustion engine, such as, for example a Tier 2 bin 4 turbo gasoline direct injection (TGDI) engine, amongst others, for emission certification testing according to FTP-75 and SFTP-US06 protocols. In other embodiments, a conventional TWC system is configured with commercially available high PGM-based Original Equipment Manufacturer (OEM) CC and OEM UF catalysts as reference catalytic system. In these embodiments, the conventional TWC system is mechanically coupled to and in fluidic communication with a substantially similar engine used for testing the aforementioned TWC systems according to FTP-75 and SFTP-US06 protocols.

In further embodiments and prior to emission testing according to FTP-75 and SFTP-US06 protocols, the aforementioned CC and UF catalysts within the TWC systems are aged employing a modified rapid aging test (RAT) cycle protocol. In these embodiments, the CC catalysts are aged employing the modified RAT cycle protocol at a bed temperature of about 1000 °C for about 50 hours. Further to these embodiments, the UF catalysts are aged employing the modified RAT cycle protocol at a bed temperature of about 900 °C for about 50 hours.

In some embodiments, catalytic efficiency of the aforementioned CC and UF catalysts measured at mid-bed and tailpipe (weighted bag results) for the TWC systems is assessed according to FTP-75 and SFTP-US06 protocols and further compared with the weighted emissions measured for the high PGM-based OEM CC and UF catalysts.

In one embodiment, the invention provides a catalytic system for treating an exhaust stream of a combustion engine, comprising: a combustion engine; a close-coupled catalytic converter configured to accept at least one exhaust gas stream from said combustion engine, the close-coupled catalytic converter comprising: a substrate; a washcoat layer overlying the substrate; a zoned-impregnation layer impregnated onto the washcoat layer, the zoned-impregnation layer including a first zone comprising a platinum group metal and a second zone comprising a platinum group metal, wherein a loading of the platinum group metal in the first zone is less than a loading of the platinum group metal in the second zone; and an overcoat layer overlying the zoned-impregnation layer and comprising iron activated rhodium and a rare earth element-based oxygen storage material. In one embodiment, the platinum group metal in the zoned-impregnation layer is selected from the group consisting of platinum, palladium, ruthenium, iridium, and rhodium, and is preferably, palladium having a loading of about 10 g/ft³ to 100 g/ft³, being preferred a loading of about 49 g/ft³. In one embodiment of the catalytic system in accordance with at least one or more of the two preceding paragraphs, the zoned-impregnation layer may further comprises barium.

In one embodiment of the catalytic system in accordance with at least one or more of the three preceding paragraphs, the first zone of the zoned-impregnation layer is disposed towards an inlet end of the catalytic converter, and the second zone of the zoned- impregnation layer is disposed towards an outlet end of the catalytic converter.

In one embodiment of the catalytic system in accordance with at least one or more of the four preceding paragraphs, the amount of the platinum group metal in the second zone is about 2.5 to 4 times the amount of the platinum group metal in the first zone. In one embodiment of the catalytic system in accordance with at least one or more of the five preceding paragraphs, a loading of the platinum group metal in the second zone is about 3 times a loading of the platinum group metal in the first zone.

In one embodiment of the catalytic system in accordance with at least one or more of the six preceding paragraphs, the overcoat layer comprises rhodium having a loading of about 1 to 10 g/ft³.

In one embodiment of the catalytic system in accordance with at least one or more of the seven preceding paragraphs, the overcoat layer comprises rhodium having a loading of 4.25 g/ft³.

In one embodiment of the catalytic system in accordance with at least one or more of the seven preceding paragraphs, the amount of iron in the overcoat layer is from about 1 to 10 weight percent based on the total weight of the overcoat layer.

In one embodiment of the catalytic system in accordance with at least one or more of the eight preceding paragraphs, the amount of iron in the overcoat layer is from about 7 weight percent based on the total weight of the overcoat layer. In one embodiment catalytic system in accordance with at least one or more of the nine preceding paragraphs, the washcoat layer comprises a rare earth element-based oxygen storage material and a support oxide selected from the group consisting of alumina, doped alumina, zirconia, doped zirconia, cerium oxide, titanium oxide, niobium oxide, silicon dioxide, and combinations thereof.

In one embodiment catalytic system in accordance with at least one or more of the ten preceding paragraphs, the doped support oxide is doped with an oxide selected from the group consisting of calcium, strontium, barium, yttrium, lanthanum, neodymium, praseodymium, niobium, silicon, tantalum, and combinations thereof.

In one embodiment of the catalytic system in accordance with at least one or more of the eleven preceding paragraphs, the rare earth elements in the overcoat and washcoat layers are selected from the group consisting of praseodymium, cerium, neodymium, and combinations thereof.

In one embodiment of the catalytic system in accordance with at least one or more of the twelve preceding paragraphs, the washcoat layer comprises lanthanum doped aluminum oxide (La-AbOs) and a cerium based oxygen storage material (Ce-based OSM). In one embodiment of the catalytic system in accordance with at least one or more of the thirteen preceding paragraphs, the system may further comprise an underfloor catalytic converter downstream of, and, in fluid communication with said closed-couple catalytic converter, the underfloor catalytic converter comprising a substrate, a washcoat overlying the substrate, an impregnation layer impregnated onto the washcoat layer, and an overcoat layer comprising iron activated rhodium and a rare earth element-based oxygen storage material.

In one embodiment, the washcoat layer of the underfloor catalytic converter comprises a rare earth element-based oxygen storage material and a support oxide selected from the group consisting of alumina, doped alumina, zirconia, doped zirconia, cerium oxide, titanium oxide, niobium oxide, silicon dioxide, and combinations thereof.

In one embodiment, the doped support oxide is doped with an oxide selected from the group consisting of calcium, strontium, barium, yttrium, lanthanum, neodymium, praseodymium, niobium, silicon, tantalum, and combinations thereof.

In one embodiment, the rare earth elements in the overcoat and washcoat layers of the underfloor catalytic converter are selected from the group consisting of praseodymium, cerium, neodvrnium, and combinations thereof. In one embodiment, the washcoat layer of the underfloor catalytic converter comprises lanthanum doped aluminum oxide (La-Al₂03) and a cerium based oxygen storage material (Ce-based OSM).

In one embodiment, the impregnation layer comprises a platinum group metal selected from the group consisting of platinum, palladium, ruthenium, iridium, and rhodium, and is preferably, palladium having a loading of about 10 g/ft³ to 100 g/ft³, with a preferred loading of about 25.5 g/ft³.

In one embodiment, the impregnation layer may further comprises barium.

In one embodiment, the overcoat layer of the underfloor catalytic converter comprises rhodium having a loading of about 1 to 10 g/ft³.

In one embodiment, wherein the overcoat layer of the underfloor catalytic converter comprises rhodium having a loading of about 4 g/ft³.

In one embodiment, wherein the amount of iron in the overcoat layer of the underfloor catalytic converter from about 1 to 10 weight percent based on the total weight of the overcoat layer.

In one embodiment, wherein the amount of iron in the overcoat layer of the underfloor catalytic converter is about 7 weight percent based on the total weight of the overcoat layer.

In one embodiment of the catalytic system in accordance with at least one or more of the twenty two preceding paragraphs, the substrate comprises a ceramic.

Aspects of the claimed invention may also be directed to a method of preparing a catalytic converter comprising the steps of: depositing a washcoat layer onto a substrate; impregnating a first solution comprising a platinum group metal onto a first zone of the washcoat layer; calcinating the impregnated first zone of the washcoat layer to define a first zoned-impregnation layer impregnated onto the first zone of the washcoat layer; impregnating a second solution comprising a platinum group metal onto a second zone of the washcoat layer; calcinating the impregnated second zone of the washcoat layer to define a second zoned-impregnation layer impregnated onto the second zone of the washcoat layer; depositing an overcoat layer onto the zoned-impregnation layer, wherein the overcoat layer comprises iron activated rhodium and a rare earth element-based oxygen storage material.

In one embodiment in accordance with the preceding paragraph the platinum group metal in the zoned-impregnation layer is selected from the group consisting of platinum, palladium, ruthenium, iridium, and rhodium.

In one embodiment in accordance with at least one or more the two preceding paragraphs, the platinum group metal in the zoned-impregnation layer is palladium having a loading of about 10 g/ft³ to 100 g/ft³, with a preferred loading of about 49 g/ft³.

In one embodiment in accordance with at least one or more the three preceding paragraphs, the zoned-impregnation layer further comprises barium.

In one embodiment in accordance with at least one or more the four preceding paragraphs, the first zone of the zoned-impregnation layer is disposed towards an inlet end of the catalytic converter, and the second zone of the zoned-impregnation layer is disposed towards an outlet end of the catalytic converter.

In one embodiment in accordance with at least one or more the five preceding paragraphs, the amount of the platinum group metal in the second zone is about 2.5 to 4 times the amount of the platinum group metal in the first zone.

In one embodiment in accordance with at least one or more the six preceding paragraphs, a loading of the platinum group metal in the second zone is about 3 times a loading of the platinum group metal in the first zone.

In one embodiment in accordance with at least one or more the seven preceding paragraphs, the overcoat layer comprises rhodium having a loading of about 1 to 10 g/ft³.

In one embodiment in accordance with at least one or more the eight preceding paragraphs, the overcoat layer comprises a rhodium loading that is about 4.25 g/ft³.

In one embodiment in accordance with at least one or more the nine preceding paragraphs, the amount of iron in the overcoat layer is from about 1 to 10 weight percent based on the total weight of the overcoat layer. In one embodiment in accordance with at least one or more the ten preceding paragraphs, the amount of iron in the overcoat layer is about 7 weight percent based on the total weight of the overcoat layer.

In one embodiment in accordance with at least one or more the eleven preceding paragraphs, washcoat layer comprises a rare earth element-based oxygen storage material and a support oxide selected from the group consisting of alumina, doped alumina, zirconia, doped zirconia, cerium oxide, titanium oxide, niobium oxide, silicon dioxide, and combinations thereof.

In one embodiment in accordance with at least one or more the twelve preceding paragraphs, the doped support oxide is doped with an oxide selected from the group consisting of calcium, strontium, barium, yttrium, lanthanum, neodymium, praseodymium, niobium, silicon, tantalum, and combinations thereof.

In one embodiment in accordance with at least one or more the thirteen preceding paragraphs, the rare earth elements in the overcoat and washcoat layers are selected from the group consisting of praseodymium, cerium, neodymium, and combinations thereof.

In one embodiment in accordance with at least one or more the fourteen preceding paragraphs, the washcoat layer comprises lanthanum doped aluminum oxide (La-Al₂03) and a cerium based oxygen storage material (Ce-based OSM).

Numerous other aspects, features and benefits of the present disclosure may be made apparent from the following detailed description taken together with the drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure can be better understood by referring to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the disclosure. In the figures, reference numerals designate corresponding parts throughout the different views.

FIG. 1 is a functional block diagram illustrating a configuration for three-way catalyst (TWC) systems including close-coupled (CC) and underfloor (UF) catalysts, according to an embodiment. FIG. 2 is a functional block diagram illustrating a PGM-based catalyst configuration for CC applications, according to an embodiment. FIG. 3 is a functional block diagram illustrating a PGM-based catalyst configuration for UF applications, according to an embodiment.

FIG. 4 is a graphical representation illustrating driving phases of the U.S Federal Test Procedure (FTP-75) employed for testing, measuring, and diagnosing catalytic performance of TWC systems as described in FIG. 1, according to an embodiment.

FIG. 5 is a graphical representation illustrating driving phases of the U.S Supplemental Federal Test Procedure (SFTP-US06) employed for testing, measuring, and diagnosing catalytic performance of TWC systems as described in FIG. 1, according to an embodiment. FIG. 6 is a graphical representation illustrating weighted CO (g/mile) values at tailpipe (TP) for TWC systems 1, 2, and 3 employed within a turbo gasoline direct injection (TGDI) engine using the FTP-75 test protocol as described in FIG. 4, according to an embodiment.

FIG. 7 is a graphical representation illustrating weighted NMHC (g/mile) values at TP for TWC systems 1, 2, and 3 employed within a TGDI engine using the FTP-75 test protocol as described in FIG. 4, according to an embodiment.

FIG. 8 is a graphical representation illustrating weighted NOx (g/mile) values at TP for TWC systems 1, 2, and 3 employed within a TGDI engine using the FTP-75 test protocol as described in FIG. 4, according to an embodiment. FIG. 9 is a graphical representation illustrating cumulative mid-bed (MB) and engine-out NOx emission results for TWC systems 1 and 3 employed within a TGDI engine at given speeds using the FTP-75 test protocol as described in FIG. 4, according to an embodiment.

FIG. 10 is a graphical representation illustrating cumulative MB and TP NOx emission results for TWC systems 3 and 4 employed within a TGDI engine at given speeds using the FTP-75 test protocol as described in FIG. 4, according to an embodiment.

FIG. 11 is a graphical representation illustrating cumulative MB and TP NOx emission results for TWC systems 1 and 3 employed within a TGDI engine at given speeds using the SFTP-US06 test protocol as described in FIG. 5, according to an embodiment. DETAILED DESCRIPTION

The present disclosure is described herein in detail with reference to embodiments illustrated in the drawings, which form a part hereof. Other embodiments may be used and/or other modifications may be made without departing from the scope or spirit of the present disclosure. The illustrative embodiments described in the detailed description are not meant to be limiting of the subject matter presented.

Definitions

As used here, the following terms have the following definitions:

"Calcination and Calcined" refers to a thermal treatment process applied to solid materials, in presence of air, to bring about a thermal decomposition, phase transition, or removal of a volatile fraction at temperatures below the melting point of the solid materials.

"Catalyst" refers to one or more materials that may be of use in the conversion of one or more other materials. "Catalyst system" refers to any system including a catalyst of at least two layers comprising a substrate, a washcoat and/or an overcoat.

"Close-coupled (CC) catalyst" refers to a catalyst located in close proximity to the engine's exhaust manifold.

"Conversion" refers to the chemical alteration of at least one material into one or more other materials.

"Federal Test Procedure (FTP) Emission Test" refers to emission certification testing procedure of light-duty vehicles in the United States.

"Impregnation (IMP)" refers to the process of imbuing or saturating a solid layer with a liquid compound or the diffusion of some element through a medium or substance. "Incipient wetness (IW)" refers to the process of adding solution of catalytic material to a dry support oxide powder until all pore volume of support oxide is filled out with solution and mixture goes slightly near saturation point. "Inlet zone" refers to a location within a catalyst that originates at the inlet end of a catalyst layer, which is the end the exhaust gas enters first, and ends at an axial distance down the catalyst layer towards the outlet end, but extends a distance that is less than the entire distance of the catalyst layer.

"Milling" refers to the operation of breaking a solid material into a desired grain or particle size.

"Non-Methane Hydrocarbons (NMHC)" refer to the sum of all hydrocarbon air pollutants except methane.

"Original Equipment Manufacturer (OEM)" refers to a manufacturer of a new vehicle or a manufacturer of any part or component that is originally installed in a new vehicle's certified emission control system.

"Outlet zone" refers to a location that originates at the outlet end of a catalyst layer, which is the end from which the exhaust gas exits, and ends at an axial distance up the catalyst layer towards the inlet end, but extends a distance that is less than the entire distance of the catalyst layer.

"Overcoat (OC) layer" refers to a catalyst layer of at least one coating that can be deposited onto at least one washcoat layer or impregnation layer.

"Oxygen storage material (OSM)" refers to a material that absorbs oxygen from oxygen rich gas flows and further able to release oxygen into oxygen deficient gas flows.

"Platinum group metals (PGM)" refers to platinum, palladium, ruthenium, iridium, osmium, and rhodium.

"Substrate" refers to any material of any shape or configuration that yields a sufficient surface area for depositing a washcoat layer and/or an overcoat layer.

"Support oxide" refers to porous solid oxides, typically mixed metal oxides, which are used to provide a high surface area that aids in oxygen distribution and exposure of catalysts to reactants, such as, for example NOx, CO, and hydrocarbons. "Three-way catalyst (TWC)" refers to a catalyst that performs the three simultaneous tasks of reduction of nitrogen oxides to nitrogen and oxygen, oxidation of carbon monoxide to carbon dioxide, and oxidation of unburnt hydrocarbons to carbon dioxide and water. "Underfloor (UF) catalyst" refers to a catalyst that is incorporated into the exhaust system of a motor vehicle, typically located beneath the floor of a vehicle, mechanically coupled downstream to a close-coupled (CC) catalyst.

"Washcoat (WC) layer" refers to a catalyst layer of at least one coating, including at least one oxide solid that can be deposited onto a substrate.

Description of the Disclosure

The present disclosure describes close-coupled (CC) and underfloor (UF) three- way catalysts that are produced according to varied catalyst configurations, which include Fe-activated Rh compositions. These CC and UF catalysts are incorporated within engine systems as components of TWC converters that are part of TWC systems for controlling and reducing engine exhaust emissions. The conversion performance of these TWC systems is assessed and compared using the driving phases described in the U.S. Federal Test Procedure (FTP-75) protocol (2014) as well as in the supplemental FTP US06 protocol (2014). These TWC systems exhibit improved catalytic performance when compared with the catalytic performance of a high PGM-based Original Equipment Manufacturer (OEM) catalyst employed in TWC applications.

TWC system configuration

FIG. 1 is a functional block diagram illustrating a configuration for three-way catalyst (TWC) systems including close-coupled (CC) and underfloor (UF) catalysts, according to an embodiment. In FIG. 1, engine system 100 includes engine 102 and TWC system 104. TWC system 104 further includes close-coupled (CC) catalyst 106 and underfloor (UF) catalyst 108. In FIG. 1, engine 102 is mechanically coupled to and in fluidic communication with TWC system 104. In TWC system 104, CC catalyst 106 is mechanically coupled to and in fluidic communication with UF catalyst 108.

In some embodiments, engine 102 can be implemented as an internal combustion engine employed within a motor vehicle, such as, for example a Tier 2 bin 4 turbo gasoline direct injection (TGDI) engine, amongst others. In these embodiments, CC catalyst 106 and UF catalyst 108 are implemented as PGM-based catalysts. Further to these embodiments, a variety of TWC systems can be configured to assess and compare the catalytic performance when employed with engine 102.

TWC system 1

In some embodiments, TWC system 104, herein referred to as TWC system 1, is implemented including high PGM-based original equipment manufacturer (OEM) CC and OEM UF catalysts. In these embodiments, CC catalyst 106 is a high PGM-based OEM CC catalyst with a PGM loading of about 98 g/ft³ palladium (Pd) and about 8.50 g/ft³ rhodium (Rh), resulting in a total PGM loading of about 106.50 g/ft³ and a substrate having a volume of about 1.7 L. Further to these embodiments, UF catalyst 108 is a high PGM- based OEM UF catalyst with a PGM loading of about 51 g/ft³ Pd and about 8 g/ft³ Rh, resulting in a total PGM loading of about 59 g/ft³ and a substrate having a volume of about 1.3 L. TWC system 2

In some embodiments, TWC system 104, herein referred to as TWC system 2, is implemented including a PGM-based CC catalyst with Fe-activated Rh loadings, herein referred to as CC Type 1 catalyst. In these embodiments, CC catalyst 106 is a CC Type 1 catalyst that includes a PGM loading of about 49 g/ft³ Pd and about 4.25 g/ft³ Rh activated with Fe₂03, resulting in a total PGM loading of about 53.25 g/ft³.

TWC system 3

In some embodiments, TWC system 104, herein referred to as TWC system 3, is implemented including a PGM-based CC catalyst as described previously above in TWC system 2 and a PGM-based UF catalyst with Fe-activated Rh loadings, herein referred to as UF Type 1 catalyst. In these embodiments, UF catalyst 108 is a UF Type 1 catalyst that includes a PGM loading of about 25.5 g/ft³ Pd and about 4 g/ft³ Rh activated with Fe₂0₃, resulting in a total PGM loading of about 29.50 g/ft³.

TWC system 4

In some embodiments, TWC system 104, herein referred to as TWC system 4, is implemented including a PGM-based CC catalyst, herein referred to as CC Type 2 catalyst, and a PGM-based UF catalyst, herein referred as UF Type 2 catalyst. In these embodiments, CC catalyst 106 is a CC Type 2 catalyst that includes a PGM loading of about 49 g/ft³ Pd and about 4.25 g/ft³ Rh, resulting in a total PGM loading of about 53.25 g/ft³. Further to these embodiments, UF catalyst 108 is a UF Type 2 catalyst that includes a PGM loading of about 25.50 g/ft³ Pd and about 4 g/ft³ Rh, resulting in a total PGM loading of about 29.50 g/ft³.

In some embodiments, TWC systems 1, 2, 3, and 4 are mechanically coupled to and in fluidic communication with a TGDI engine used for testing the aforementioned TWC systems. Material composition of PGM layers employed within CC and UF catalysts

In some embodiments, a PGM composition includes platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), and rhodium (Rh), either by themselves, or in combinations thereof employing different loadings. In an example, the PGM composition includes Pd loadings within a range from about 10 g/ft³ to about 100 g/ft³, alone or in combination with Ba loadings. In another example, the PGM composition includes Rh loadings within a range from about 1 g/ft³ to about 10 g/ft³, alone or activated with Fe₂03.

CC catalyst configuration and production

FIG. 2 is a functional block diagram illustrating a PGM-based catalyst configuration for CC applications, according to an embodiment. In FIG. 2, catalyst configuration 200 includes substrate 202, washcoat (WC) layer 204, zoned-impregnation (ZIMP) layer 206, and overcoat (OC) layer 208. In FIG. 2, ZIMP layer 206 further includes inlet zone 210 and outlet zone 212. In some embodiments, WC layer 204 is coated onto substrate 202. In these embodiments, ZIMP layer 206 is impregnated onto WC layer 204. Further to these embodiments, OC layer 208 is coated onto ZIMP layer 206.

In some embodiments, substrate 202 materials include a refractive material, a ceramic material, a honeycomb structure, a metallic material, a ceramic foam, a metallic foam, a reticulated foam, or suitable combinations, amongst others. In these embodiments, WC layer 204 is implemented as a mixture of support oxides and rare-earth (RE) metals- based oxygen storage materials (OSM). Further to these embodiments, ZIMP layer 206 is implemented as a PGM composition, alone or in combination with Ba loadings. Still further to these embodiments, OC layer 208 is implemented as a PGM composition metalized onto a base metal oxide deposited onto RE metals-OSM.

In some embodiments, support oxides include alumina (A1₂0₃), doped A1₂0₃, zirconia (Zr0₂), doped Zr0₂, Ce0₂, Ti0₂, Nb₂Os, Si0₂, or mixtures thereof, amongst others. In these embodiments, doping materials within doped support oxides include Ca, Sr, Ba, Y, La, Ce, Nd, Pr, Nb, Si, or Ta oxides, amongst others. Further to these embodiments, RE-based OSM includes Pr, Ce, and Nd, or mixtures thereof, amongst others. In a first example, a CC catalyst, herein referred to as CC Type 1 catalyst, is produced including a ceramic substrate, such as, for example a 600/3 1.7 L substrate having a diameter (D) of 118.4 mm and a length (L) of 153.9 mm. In this example, the WC layer comprises a mixture of La-doped AI2O3 and Ce-based OSM. Further to this example, the ZIMP layer includes an inlet zone of a Pd loading of about 12.43 g/ft³ and an outlet zone of a Pd loading of about 36.57 g/ft³ with Ba loadings, each zone impregnated onto associated portion of the WC layer. Still further to this example, the OC layer comprises a Rh loading of about 4.25 g/ft³ activated with Fe₂03 deposited onto Ce-based OSM.

In this example, the production of the WC layer for CC Type 1 catalyst begins with the preparation of a mixture comprising La-doped AI2O3 and Ce-based OSM mixed at a plurality of ratios (e.g., 1: 1 by weight). Further to this example, the mixture of La-doped AI2O3 and Ce-based OSM are milled with water to produce a slurry of La-doped AI2O3 and Ce-based OSM. Still further to this example, the slurry of La-doped AI2O3 and Ce- based OSM is then coated onto the substrate and further calcined at about 550 °C for about 4 hours to produce the WC layer. In this example, the production of the ZIMP layer for CC Type 1 catalyst begins by separately preparing solutions of Pd nitrate with PGM loadings of about 12.43 g/ft³ Pd and about 36.57 g/ft³ Pd with Ba loadings of about 0.5M, for inlet and outlet zones, respectively. Further to this example, the first Pd nitrate solution (12.43 g/ft³) is impregnated onto a portion of the WC layer to produce the inlet zone and then calcined at about 550 °C for about 4 hours to produce the inlet zone IMP layer within ZIMP layer. Still further to this example, the second Pd nitrate solution (36.57 g/ft³) is impregnated onto another portion of the WC layer to produce the outlet zone. In this example, after impregnating the Pd onto the back zone of WC layer is calcined at about 550 °C for about 4 hours to produce the ZIMP layer. In this example, the production of the OC layer for CC Type 1 catalyst begins with the preparation of a base metal nitrate solution. Further to this example, the base metal nitrate solution is implemented as a Fe nitrate solution. Still further to this example, the Fe nitrate solution is drop-wise added to a Ce-based OSM powder via incipient wetness (IW) methodology employing a Fe loading from about 1 wt% to about 10 wt%, preferably a 7.37wt% Fe loading is employed. In this example, the Fe-doped Ce-based OSM is then dried at 120 °C overnight and further calcined in a temperature range from about 600 °C to about 800 °C, preferably at about 750 °C, for about 5 hours. Further to this example, the calcined material of Fe₂03 and Ce-based OSM is subsequently ground into fine powder, and further milled with water to produce a slurry of Fe₂03/Ce-based OSM. Still further to this example, the slurry of Fe₂03/Ce-based OSM is metalized with the Rh nitrate solution to produce a slurry of Fe-activated Rh and Ce-based OSM having a PGM loading of about 4.25 g/ft³ Rh. In this example, the slurry of Fe-activated Rh and Ce-based OSM is coated onto the ZIMP layer, and further dried and calcined at a temperature of about 550 °C for about 4 hours to produce the CC Type 1 catalyst.

In a second example, a CC catalyst, herein referred to as CC Type 2 catalyst, is produced including a ceramic substrate, such as, for example a 600/3 1.7 L substrate having a diameter (D) of 118.4 mm and a length (L) of 153.9 mm. In this example, the WC layer comprises a mixture of La-doped A1₂0₃ and Ce-based OSM, as described previously above. Further to this example, the ZIMP layer includes an inlet zone of a Pd loading of about 12.43 g/ft³ and an outlet zone of a Pd loading of about 36.57 g/ft³ with Ba loadings, each zone impregnated onto associated portion of the WC layer, as described previously above. Still further to this example, the OC layer comprises a Rh loading of about 4.25 g/ft³ deposited onto Ce-based OSM.

In this example, the production of the WC and ZIMP layers for CC Type 2 catalyst is performed in a substantially similar manner as described previously above for CC Type 1 catalyst. Further to this example, the production of the OC layer for CC Type 2 catalyst begins with the preparation of a solution of Rh nitrate with a PGM loading of about 4.25 g/ft³ Rh. Still further to this example, the Ce-based OSM powder is milled separately and metalized with the Rh nitrate solution to produce a slurry of Rh/Ce-based OSM. In this example, the slurry of Rh/Ce-based OSM is coated onto the ZIMP layer and further dried and calcined at a temperature of about 550 °C for about 4 hours to produce the CC Type 2 catalyst.

UF catalyst configuration and production

FIG. 3 is a functional block diagram illustrating a PGM-based catalyst configuration for UF applications, according to an embodiment. In FIG. 3, catalyst configuration 300 includes substrate 202, WC layer 204, impregnation (IMP) layer 302, and OC layer 208. In some embodiments, WC layer 204 is coated onto substrate 202. In these embodiments, IMP layer 302 is impregnated onto WC layer 204. Further to these embodiments, OC layer 208 is coated onto IMP layer 302. In FIG. 3, elements having substantially similar element numbers from previous figures function in a substantially similar manner. In some embodiments, IMP layer 302 is implemented as a PGM composition in combination with Ba loadings.

In a third example, a UF catalyst, herein referred to as UF Type 1 catalyst, is produced including a ceramic substrate, such as, for example a 400/3 1.3 L substrate having a diameter (D) of 118.4 mm and a length (L) of 118.0 mm. In this example, the WC layer comprises a mixture of La-doped AI2O3 and Ce-based OSM, as described previously above. Further to this example, the IMP layer comprises a Pd loading of about 25.50 g/ft³ with Ba loadings. Still further to this example, the OC layer comprises a Rh loading of about 4 g/ft³ activated with Fe₂03 deposited onto Ce-based OSM, as described previously above.

In this example, the production of the WC and OC layers for UF Type 1 catalyst is performed in a substantially similar manner as described previously above for CC Type 1 catalyst. Further to this example, the production of the IMP layer begins with the preparation of a solution of Pd nitrate with a PGM loading of about 25.50 g/ft³ Pd with Ba loadings of about 0.5M. Still further to this example, the solution of Pd nitrate + Ba solution is impregnated onto the WC layer and further calcined at about 550 °C for about 4 hours to produce the IMP layer.

In a fourth example, a UF catalyst, herein referred to as UF Type 2 catalyst, is produced including a ceramic substrate, such as, for example a 400/3 1.3 L substrate having a diameter (D) of 118.4 mm and a length (L) of 118.0 mm. In this example, the WC layer comprises a mixture of La-doped AI2O3 and Ce-based OSM, as described previously above. Further to this example, the IMP layer comprises a Pd loading of about 25.50 g/ft³ with Ba loadings, as described previously above. Still further to this example, the OC layer comprises a Rh loading of about 4 g/ft³ deposited onto Ce-based OSM, as described previously above.

In this example, the production of the WC and OC layers for UF Type 2 catalyst is performed in a substantially similar manner as described previously above for CC Type 2 catalyst. Further to this example, the IMP layer for UF Type 2 catalyst is performed in a substantially similar manner as described previously above for UF Type 1 catalyst. Aging and testing conditions for the CC and UF catalysts

In some embodiments and prior to emission testing according to FTP-75 and SFTP-US06, the aforementioned CC and UF catalysts within the TWC systems 1, 2, 3, and 4 are aged employing a modified rapid aging test (RAT) cycle protocol. In these embodiments, the CC catalysts are aged employing the modified RAT cycle protocol at a bed temperature of about 1000 °C for about 50 hours. Further to these embodiments, the UF catalysts are aged employing the modified RAT cycle protocol at a bed temperature of about 900 °C for about 50 hours.

U.S. Federal Test Procedure (FTP-75)

FIG. 4 is a graphical representation illustrating driving phases of the U.S Federal

Test Procedure (FTP-75) employed for testing, measuring, and diagnosing catalytic performance of TWC systems as described in FIG. 1, according to an embodiment. In FIG. 4, FTP-75 protocol 400 includes cold start phase 402, stabilized phase 404, and hot start phase 406.

In some embodiments, cold start phase 402 illustrates a phase of FTP-75 testing to measure mid-bed and tailpipe emissions and performance of the aforementioned TWC systems. In these embodiments, said driving phase is a cold start transient phase at ambient temperature of about 20 °C to about 30 °C performed for a time duration from zero to 505 seconds. Further to these embodiments, stabilized phase 404 illustrates a phase for driving conditions from about 506 seconds to about 1372 seconds performed after cold start phase 402. Still further to these embodiments and after stabilized phase 404 is finished, the engine is stopped for about 10 minutes and then hot start phase 406 begins. In these embodiments, hot start phase 406 illustrates two segments of driving conditions performed after stabilized phase 404 as follows: (1) a hot soak performed for a minimum time duration of about 540 seconds or a maximum time duration of about 660 seconds, and (2) a hot start transient phase performed for a time duration from zero to about 505 seconds. Further to these embodiments, mid-bed and tailpipe emissions from each phase are collected in a separate bag, analyzed, and expressed in g/mile.

U.S. Supplemental FTP US06

FIG. 5 is a graphical representation illustrating driving phases of the U.S

Supplemental Federal Test Procedure (SFTP-US06) employed for testing, measuring, and diagnosing catalytic performance of TWC systems as described in FIG. 1, according to an embodiment. In FIG. 5, SFTP-US06 protocol 500 includes first city phase 502, highway phase 504, and second city phase 506.

In some embodiments, SFTP-US06 testing cycle address the shortcomings with the FTP-75 testing cycle in the representation of aggressive, high speed and/or high acceleration driving behavior, rapid speed fluctuations, and driving behavior following startup. In these embodiments, the SFTP-US06 testing cycle involves higher rates of acceleration and higher speeds (up to 80 MPH) than the other conventional certification cycles. Further to these embodiments, the SFTP-US06 testing cycle comprises multiple phases that are designated as "city" and "highway" . Still further to these embodiments, the SFTP-US06 city phase is a combination of two separated segments (first city phase 502 and second city phase 506) within the overall testing cycle that occur at the beginning and at the end and include multiple accelerations and decelerations that are typical in urban driving. In these embodiments, the SFTP-US06 highway phase (highway phase 504) comprises a long period of nonstop driving in the middle of the testing cycle that models interstate highway driving. Further to these embodiments, mid-bed and tailpipe emissions from each phase are collected in a separate bag, analyzed, and expressed in g/mile.

In some embodiments, the SFTP-US06 testing cycle is a high speed/quick acceleration loop that lasts about 596 seconds, covers a distance of about 8.01 miles (13 km) at an average speed of about 48.4 miles/h (77.9 km/h) reaching a maximum speed of about 80.3 miles/h (129.2 km/h). In these embodiments, the SFTP-US06 testing cycle includes four stops as well as brisk acceleration at a rate of about 8.46 mph (13.62 km/h) per second. Further to these embodiments, when conducting the SFTP-US06 testing cycle the engine is tested at operating temperature and air conditioning is not used. Still further to these embodiments, the ambient temperature when conducting the SFTP-US06 testing cycle varies from about 68 °F (20 °C) to about 86 °F (30 °C).

Engine specifications for implementation of the testing cycles

In some embodiments and referring to FIG. 1, engine 102 is implemented as a TGDI engine with an electronically controlled twin-scroll turbocharger, dual overhead camshaft (DOHC) engine with continuously variable valve timing in which direct injection is performed employing a cam-driven high pressure fuel pump. In these embodiments, the TGDI engine includes a two-stage variable displacement oil pump, an air-to-air intercooling system, and a cast aluminum engine block. Major specifications of the TGDI engine are illustrated in Table 1, below.

Table 1. TGDI engine specifications.

Weighted emission bag results from FTP- 75 test

FIG. 6 is a graphical representation illustrating weighted CO (g/mile) values at tailpipe (TP) for TWC systems 1, 2, and 3 employed within a turbo gasoline direct injection (TGDI) engine using the FTP-75 test protocol as described in FIG. 4, according to an embodiment. In FIG. 6, TP weighted CO emission 600 includes TWC system 1 TP weighted CO 602, TWC system 2 TP weighted CO 610, and TWC system 3 TP weighted CO 618.

In some embodiments, TWC system 1 TP weighted CO 602 includes three specific TP weighted CO bars as follows: TP weighted CO bar 604, TP weighted CO bar 606, and TP weighted CO bar 608. In these embodiments, each CO bar illustrates the FTP-75 bag results in g/mile of weighted CO for a cold start phase, a stabilized phase, and a hot start phase, respectively, obtained when measuring TP CO emissions associated with a TWC system. In an example, each CO bar illustrates the FTP-75 bag results in g/mile of weighted CO for cold start phase 402, stabilized phase 404, and hot start phase 406, respectively, obtained when measuring TP CO emissions associated with TWC system 1. In other embodiments, TWC system 2 TP weighted CO 610 includes three specific

TP weighted CO bars as follows: TP weighted CO bar 612, TP weighted CO bar 614, and TP weighted CO bar 616. In another example, each CO bar illustrates the FTP-75 bag results in g/mile of weighted CO for cold start phase 402, stabilized phase 404, and hot start phase 406, respectively, obtained when measuring TP CO emissions associated with TWC system 2. In further embodiments, TWC system 3 TP weighted CO 618 includes three specific TP weighted CO bars as follows: TP weighted CO bar 620, TP weighted CO bar 622, and TP weighted CO bar 624. In yet another example, each CO bar illustrates the FTP-75 bag results in g/mile of weighted CO for cold start phase 402, stabilized phase 404, and hot start phase 406, respectively, obtained when measuring TP CO emissions associated with TWC system 3.

In some embodiments, TP weighted CO emissions collected in g/mile during implementation of FTP-75 testing associated with TWC systems 1, 2, and 3 are detailed in Table 2, below. In these embodiments, TWC systems 2 and 3 exhibit lower TP weighted CO values when compared to TWC system 1. Further to these embodiments, TWC system 2 that includes a CC Type 1-only catalyst (53.25 g/ft³ PGM loading) exhibits more efficient TP CO conversion than a TWC system 1 that includes OEM CC and UF catalysts (165.5 g/ft³ PGM loading). These results confirm that the CC Type 1-only catalyst provides improved CO conversion, thereby reducing a two-catalyst TWC system (e.g., TWC system 1) to a single catalyst (e.g., TWC system 2).

Table 2. TP weighted CO emission values associated with TWC systems 1, 2, and 3, as illustrated in FIG. 6.

FIG. 7 is a graphical representation illustrating weighted NMHC (g/mile) values at TP for TWC systems 1, 2, and 3 employed within a TGDI engine using the FTP-75 test protocol as described in FIG. 4, according to an embodiment. In FIG. 7, TP weighted NMHC emission 700 includes TWC system 1 TP weighted NMHC 702, TWC system 2 TP weighted NMHC 710, and TWC system 3 TP weighted NMHC 718. In some embodiments, TWC system 1 TP weighted NMHC 702 includes three specific TP weighted NMHC bars as follows: TP weighted NMHC bar 704, TP weighted NMHC bar 706, and TP weighted NMHC bar 708. In these embodiments, each NMHC bar illustrates the FTP-75 bag results in g/mile of weighted NMHC for a cold start phase, a stabilized phase, and a hot start phase, respectively, obtained when measuring TP NMHC emissions associated with a TWC system. In an example, each NMHC bar illustrates the FTP-75 bag results in g/mile of weighted NMHC for cold start phase 402, stabilized phase 404, and hot start phase 406, respectively, obtained when measuring TP NMHC emissions associated with TWC system 1. In other embodiments, TWC system 2 TP weighted NMHC 710 includes three specific TP weighted NMHC bars as follows: TP weighted NMHC bar 712, TP weighted NMHC bar 714, and TP weighted NMHC bar 716. In another example, each NMHC bar illustrates the FTP-75 bag results in g/mile of weighted NMHC for cold start phase 402, stabilized phase 404, and hot start phase 406, respectively, obtained when measuring TP NMHC emissions associated with TWC system 2.

In further embodiments, TWC system 3 TP weighted NMHC 718 includes three specific TP weighted NMHC bars as follows: TP weighted NMHC bar 720, TP weighted NMHC bar 722, and TP weighted NMHC bar 724. In yet another example, each NMHC bar illustrates the FTP-75 bag results in g/mile of weighted NMHC for cold start phase 402, stabilized phase 404, and hot start phase 406, respectively, obtained when measuring TP NMHC emissions associated with TWC system 3.

In some embodiments, TP weighted NMHC emissions collected in g/mile during implementation of FTP-75 testing associated with TWC systems 1, 2, and 3 are detailed in Table 3, below. In these embodiments, TWC systems 2 and 3 exhibit substantially similar NMHC conversion levels. Further to these embodiments, TWC system 1 exhibits lower TP weighted NMHC values when compared to TWC systems 2 and 3. Still further to these embodiments, TWC systems 2 and 3 exhibit lower TP weighted NMHC values when compared with the U.S. Tier 2 bin 3 emission standard (NMHC = 0.055 g/mile) for light- duty engines. Table 3. TP weighted NMHC emission values associated with TWC systems 1, 2, and 3, as illustrated in FIG. 7.

FIG. 8 is a graphical representation illustrating weighted NOx (g/mile) values at TP for TWC systems 1, 2, and 3 employed within a TGDI engine using the FTP-75 test protocol as described in FIG. 4, according to an embodiment. In FIG. 8, TP weighted NOx emission 800 includes TWC system 1 TP weighted NOx 802, TWC system 2 TP weighted NOx 810, and TWC system 3 TP weighted NOx 818.

In some embodiments, TWC system 1 TP weighted NOx 802 includes three specific TP weighted NOx bars as follows: TP weighted NOx bar 804, TP weighted NOx bar 806, and TP weighted NOx bar 808. In these embodiments, each NOx bar illustrates the FTP-75 bag results in g/mile of weighted NOx for a cold start phase, a stabilized phase, and a hot start phase, respectively, obtained when measuring TP NOx emissions associated with a TWC system. In an example, each NOx bar illustrates the FTP-75 bag results in g/mile of weighted NOx for cold start phase 402, stabilized phase 404, and hot start phase 406, respectively, obtained when measuring TP NOx emissions associated with TWC system 1.

In other embodiments, TWC system 2 TP weighted NOx 810 includes three specific TP weighted NOx bars as follows: TP weighted NOx bar 812, TP weighted NOx bar 814, and TP weighted NOx bar 816. In another example, each NOx bar illustrates the FTP-75 bag results in g/mile of weighted NOx for cold start phase 402, stabilized phase 404, and hot start phase 406, respectively, obtained when measuring TP NOx emissions associated with TWC system 2. In further embodiments, TWC system 3 TP weighted NOx 818 includes three specific TP weighted NOx bars as follows: TP weighted NOx bar 820, TP weighted NOx bar 822, and TP weighted NOx bar 824. In yet another example, each NOx bar illustrates the FTP-75 bag results in g/mile of weighted NOx for cold start phase 402, stabilized phase 404, and hot start phase 406, respectively, obtained when measuring TP NOx emissions associated with TWC system 3.

In some embodiments, TP weighted NOx emissions collected in g/mile during implementation of FTP-75 testing associated with TWC systems 1, 2, and 3 are detailed in Table 4, below. In these embodiments, TWC system 3 exhibits lower TP weighted NOx values when compared to TWC systems 1 and 2. Further to these embodiments, TWC systems 1 and 2 exhibit substantially similar NOx conversion levels, thereby confirming that employing the CC Type 1-only catalyst (53.25 g/ft³ PGM loading) is as efficient as employing high PGM-based OEM CC and UF catalysts (165.50 g/ft³ PGM loading) for NOx conversion. Table 4. TP weighted NOx emission values associated with TWC systems 1, 2, and 3, as illustrated in FIG. 8.

In summary, the catalytic behavior exhibited by TWC system 2 during each one of the FTP-75 phases confirms significant NOx, CO and NMHC conversion performance as effectively as employing a high PGM-based TWC system 1. The improved conversion performance in case of TWC system 2 is enabled by CC Type 1 catalyst, which includes an OC layer comprising Fe-activated Rh composition with a loading of about 4.25 g/ft³ Rh. FIG. 9 is a graphical representation illustrating cumulative mid-bed (MB) and engine-out NOx emission results for TWC systems 1 and 3 employed within a TGDI engine at given speeds using the FTP-75 test protocol as described in FIG. 4, according to an embodiment. In FIG. 9, cumulative NOx values comparison 900 includes cumulative NOx curve 902, cumulative NOx curve 904, cumulative NOx curve 906, cumulative NOx curve 908, and FTP-75 protocol 400. In FIG. 9, elements having substantially similar element numbers from previous figures function in a substantially similar manner.

In some embodiments, cumulative NOx curve 902 illustrates cumulative NOx emission results obtained at MB associated with TWC system 1 at given speeds. In these embodiments, cumulative NOx curve 904 illustrates cumulative NOx emission results obtained at MB associated with TWC system 3 at given speeds. Further to these embodiments, the scale associated with the relative values for cumulative NOx curve 902 and cumulative NOx curve 904 is located along the y-axis to the right of cumulative NOx values comparison 900 and labeled as Mid-Bed Cumulative NOx Emissions (g). In these embodiments, cumulative NOx curve 906 illustrates cumulative NOx emission results obtained at engine-out (pre-catalyst) associated with TWC system 1 at given speeds. Further to these embodiments, cumulative NOx curve 908 illustrates cumulative NOx emission results obtained at engine-out (pre-catalyst) associated with TWC system 3 at given speeds. Still further to these embodiments, the scale associated with the relative values for cumulative NOx curve 906 and cumulative NOx curve 908 is located along the y-axis to the left of cumulative NOx values comparison 900 and labeled as Εουτ (g cumulative), Speed (mph).

In some embodiments, cumulative MB NOx values (cumulative NOx curve 904) associated with TWC system 3 are significantly lower than cumulative MB NOx values (cumulative NOx curve 902) associated with TWC system 1. In these embodiments, the improvement in MB NOx emission (cumulative NOx curve 904) indicates CC Type 1 catalyst exhibits greater catalytic functionality when compared to a PGM-based OEM CC catalyst. Further to these embodiments, TWC system 3 reduces cumulative MB NOx values by employing 50% less PGM. Still further to these embodiments, cumulative engine-out NOx emissions associated with TWC systems 1 and 3 exhibit substantially similar levels. In summary, TWC system 3 exhibits higher NOx conversion efficiency than TWC system 1. FIG. 10 is a graphical representation illustrating cumulative MB and TP NOx emission results for TWC systems 3 and 4 employed within a TGDI engine at given speeds using the FTP-75 test protocol as described in FIG. 4, according to an embodiment. In FIG. 10, cumulative NOx values comparison 1000 includes cumulative NOx curve 1002, cumulative NOx curve 1004, cumulative NOx curve 1006, cumulative NOx curve 1008, and FTP-75 protocol 400. In FIG. 10, elements having substantially similar element numbers from previous figures function in a substantially similar manner.

In some embodiments, cumulative NOx curve 1002 illustrates cumulative NOx emission results obtained at MB associated with TWC system 4 at given speeds. In these embodiments, cumulative NOx curve 1004 illustrates cumulative NOx emission results obtained at TP associated with TWC system 4 at given speeds. Further to these embodiments, cumulative NOx curve 1006 illustrates cumulative NOx emission results obtained at MB associated with TWC system 3 at given speeds. Still further to these embodiments, cumulative NOx curve 1008 illustrates cumulative NOx emission results obtained at TP associated with TWC system 3 at given speeds.

In some embodiments, cumulative MB NOx values (cumulative NOx curve 1006) associated with TWC system 3 are significantly lower than cumulative MB NOx values (cumulative NOx curve 1002) associated with TWC system 4. In these embodiments, cumulative TP NOx values (cumulative NOx curve 1008) associated with TWC system 3 are significantly lower than cumulative TP NOx values (cumulative NOx curve 1004) associated with TWC system 4. Further to these embodiments, cumulative MB and TP NOx emissions associated with TWC systems 3 exhibit substantially similar levels (cumulative NOx curve 1006 and cumulative NOx curve 1008). Still further to these embodiments, TWC system 3 exhibits improved NOx conversion at higher space velocities (e.g., second acceleration in hill 2 at about 20,000 seconds). In summary, TWC system 3 exhibits higher NOx conversion efficiency than TWC system 4.

Weighted emission bag results from SFTP-US06 test

FIG. 11 is a graphical representation illustrating cumulative MB and TP NOx emission results for TWC systems 1 and 3 employed within a TGDI engine at given speeds using the SFTP-US06 test protocol as described in FIG. 5, according to an embodiment. In FIG. 11, cumulative NOx values comparison 1100 includes cumulative NOx curve 1102, cumulative NOx curve 1104, cumulative NOx curve 1106, cumulative NOx curve 1108, and SFTP-US06 protocol 500. In FIG. 11, elements having substantially similar element numbers from previous figures function in a substantially similar manner.

In some embodiments, cumulative NOx curve 1102 illustrates cumulative NOx emission results obtained at MB associated with TWC system 1 at given speeds. In these embodiments, cumulative NOx curve 1104 illustrates cumulative NOx emission results obtained at TP associated with TWC system 1 at given speeds. Further to these embodiments, cumulative NOx curve 1106 illustrates cumulative NOx emission results obtained at MB associated with TWC system 3 at given speeds. Still further to these embodiments, cumulative NOx curve 1108 illustrates cumulative NOx emission results obtained at TP associated with TWC system 3 at given speeds.

In some embodiments, cumulative MB NOx values (cumulative NOx curve 1106) associated with TWC system 3 are significantly lower than cumulative MB NOx values (cumulative NOx curve 1102) associated with TWC system 1. In these embodiments, the improvement in MB NOx emission (cumulative NOx curve 1106) indicates CC Type 1 catalyst exhibits greater catalytic functionality when compared to a PGM-based OEM CC catalyst. Further to these embodiments, TWC system 3 reduces cumulative MB NOx values by employing 50% less PGM. Still further to these embodiments, cumulative TP NOx values (cumulative NOx curve 1108) associated with TWC system 3 are lower than cumulative TP NOx values (cumulative NOx curve 1104) associated with TWC system 1. In summary, TWC system 3 exhibits higher NOx conversion efficiency than TWC system 1.

While various aspects and embodiments have been disclosed, other aspects and embodiments may be contemplated. The various aspects and embodiments disclosed here are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Claims

CLAIMS What is claimed is:

1. A catalytic system for treating an exhaust stream of a combustion engine, comprising:

a combustion engine;

a close-coupled catalytic converter configured to accept at least one exhaust gas stream from said combustion engine, the close-coupled catalytic converter comprising:

a substrate;

a washcoat layer overlying the substrate;

a zoned-impregnation layer impregnated onto the washcoat layer, the zoned-impregnation layer including a first zone comprising a platinum group metal and a second zone comprising a platinum group metal, wherein a loading of the platinum group metal in the first zone is less than a loading of the platinum group metal in the second zone; and

an overcoat layer overlying the zoned-impregnation layer and comprising iron activated rhodium and a rare earth element-based oxygen storage material.

2. The catalytic system of claim 1, wherein the platinum group metal in the zoned-impregnation layer is selected from the group consisting of platinum, palladium, ruthenium, iridium, and rhodium.

3. The catalytic system of one of the preceding claims, wherein the platinum group metal in the zoned-impregnation layer is palladium having a loading of about 10 g/ft³ to 100 g/ft³.

4. The catalytic system of one of the preceding claims, wherein the platinum group metal in the zoned-impregnation layer is palladium having a loading of about 49 g/ft³.

5. The catalytic system of one of the preceding claims, wherein the zoned- impregnation layer further comprises barium.

6. The catalytic system of one of the preceding claims, wherein the first zone of the zoned-impregnation layer is disposed towards an inlet end of the catalytic converter, and the second zone of the zoned-impregnation layer is disposed towards an outlet end of the catalytic converter.

7. The catalytic system of one of the preceding claims, wherein the amount of the platinum group metal in the second zone is about 2.5 to 4 times the amount of the platinum group metal in the first zone.

8. The catalytic system of one of the preceding claims, wherein a loading of the platinum group metal in the second zone is about 3 times a loading of the platinum group metal in the first zone.

9. The catalytic system of one of the preceding claims, wherein the overcoat layer comprises rhodium having a loading of about 1 to 10 g/ft³.

10. The catalytic system of one of the preceding claims, wherein the overcoat layer comprises rhodium having a loading of about 4.25 g/ft³.

11. The catalytic system of one of the preceding claims, wherein the amount of iron in the overcoat layer is from about 1 to 10 weight percent based on the total weight of the overcoat layer.

12. The catalytic system of one of the preceding claims, wherein the amount of iron in the overcoat layer is about 7 weight percent based on the total weight of the overcoat layer.

13. The catalytic system of one of the preceding claims, wherein the washcoat layer comprises a rare earth element-based oxygen storage material and a support oxide selected from the group consisting of alumina, doped alumina, zirconia, doped zirconia, cerium oxide, titanium oxide, niobium oxide, silicon dioxide, and combinations thereof.

14. The catalytic system of claim 13, wherein the doped support oxide is doped with an oxide selected from the group consisting of calcium, strontium, barium, yttrium, lanthanum, neodymium, praseodymium, niobium, silicon, tantalum, and combinations thereof.

15. The catalytic system of one of the preceding claims, wherein the rare earth elements in the overcoat and washcoat layers are selected from the group consisting of praseodymium, cerium, neodymium, and combinations thereof.

16. The catalytic system of one of the preceding claims, wherein the washcoat layer comprises lanthanum doped aluminum oxide (La-Al₂03) and a cerium based oxygen storage material (Ce-based OSM).

17. The catalytic system of one of the preceding claims, wherein the system further comprises an underfloor catalytic converter downstream of, and, in fluid communication with said close-coupled catalytic converter, the underfloor catalytic converter comprising:

a substrate;

a washcoat layer overlying the substrate;

an impregnation layer impregnated onto the washcoat layer; and

an overcoat layer overlying the impregnation layer and comprising iron activated rhodium and a rare earth element-based oxygen storage material.

18. The catalytic system of claim 17, wherein the washcoat layer of the underfloor catalytic converter comprises a rare earth element-based oxygen storage material and a support oxide selected from the group consisting of alumina, doped alumina, zirconia, doped zirconia, cerium oxide, titanium oxide, niobium oxide, silicon dioxide, and combinations thereof.

19. The catalytic system of claim 18, wherein the doped support oxide is doped with an oxide selected from the group consisting of calcium, strontium, barium, yttrium, lanthanum, neodymium, praseodymium, niobium, silicon, tantalum, and combinations thereof.

20. The catalytic system of any one of claims 17 to 19, wherein the rare earth elements in the overcoat and washcoat layers of the underfloor catalytic converter are selected from the group consisting of praseodymium, cerium, neodymium, and combinations thereof.

21. The catalytic system of any one of claims 17 to 20, wherein the washcoat layer of the underfloor catalytic converter comprises lanthanum doped aluminum oxide (La-Al₂03) and a cerium based oxygen storage material (Ce-based OSM).

22. The catalytic system of any one of claims 17 to 21, wherein the impregnation layer comprises a platinum group metal selected from the group consisting of platinum, palladium, ruthenium, iridium, and rhodium.

23. The catalytic system according to claim 22, wherein the platinum group metal in the impregnation layer is palladium having a loading of about 10 g/ft³ to 100 g/ft³.

24. The catalytic system according to claim 23, wherein the platinum group metal in the impregnation layer is palladium having a loading of about 25.5 g/ft³.

25. The catalytic system of any one of claims 22 to 23, wherein the impregnation layer further comprises barium.

26. The catalytic system of any one of claims 17 to 25, wherein the overcoat layer of the underfloor catalytic converter comprises rhodium having a loading of about 1 to 10 g/ft³.

27. The catalytic system according to claim 26, wherein the overcoat layer of the underfloor catalytic converter comprises rhodium having a loading of about 4 g/ft³.

28. The catalytic system of any one of claims 17 to 27, wherein the amount of iron in the overcoat layer of the underfloor catalytic converter from about 1 to 10 weight percent based on the total weight of the overcoat layer.

29. The catalytic system according to claim 28, wherein the amount of iron in the overcoat layer of the underfloor catalytic converter is about 7 weight percent based on the total weight of the overcoat layer.

30. A method of preparing a catalytic converter comprising the steps of:

depositing a washcoat layer onto a substrate;

impregnating a first solution comprising a platinum group metal onto a first zone of the washcoat layer; calcinating the impregnated first zone of the washcoat layer to define a first zoned-impregnation layer impregnated onto the first zone of the washcoat layer;

impregnating a second solution comprising a platinum group metal onto a second zone of the washcoat layer;

calcinating the impregnated second zone of the washcoat layer to define a second zoned-impregnation layer impregnated onto the second zone of the washcoat layer;

depositing an overcoat layer onto the zoned-impregnation layer, wherein the overcoat layer comprises iron activated rhodium and a rare earth element-based oxygen storage material.

31. The method of claim 30, wherein the platinum group metal in the zoned- impregnation layer is selected from the group consisting of platinum, palladium, ruthenium, iridium, and rhodium.

32. The method of claim 30, wherein the platinum group metal in the zoned- impregnation layer is palladium having a loading of about 10 g/ft³ to 100 g/ft³.

33. The method of claim 32, wherein the platinum group metal in the zoned- impregnation layer is palladium having a loading of about 49 g/ft³.

34. The method of any one of claims 30 to 33, wherein the zoned-impregnation layer further comprises barium.

35. The method of any one of claims 30 to 33, wherein the first zone of the zoned-impregnation layer is disposed towards an inlet end of the catalytic converter, and the second zone of the zoned-impregnation layer is disposed towards an outlet end of the catalytic converter.

36. The method of any one of claims 30 to 35, wherein the amount of the platinum group metal in the second zone is about 2.5 to 4 times the amount of the platinum group metal in the first zone.

37. The method of any one of claims 30 to 36, wherein a loading of the platinum group metal in the second zone is about 3 times a loading of the platinum group metal in the first zone.

38. The method of claim 30, wherein the overcoat layer comprises rhodium having a loading of about 1 to 10 g/ft³.

39. The method of claim 38, wherein the overcoat layer comprises rhodium having a loading of about 4.25 g/ft³.

40. The method of any one of claims 30 to 39, wherein the amount of iron in the overcoat layer is from about 1 to 10 weight percent based on the total weight of the overcoat layer.

41. The method of any one of claims 30 to 40, wherein the amount of iron in the overcoat layer is about 7 weight percent based on the total weight of the overcoat layer.

42. The method of any one of claims 30 to 41, wherein the washcoat layer comprises a rare earth element-based oxygen storage material and a support oxide selected from the group consisting of alumina, doped alumina, zirconia, doped zirconia, cerium oxide, titanium oxide, niobium oxide, silicon dioxide, and combinations thereof.

43. The method of any one of claims 30 to 42, wherein the doped support oxide is doped with an oxide selected from the group consisting of calcium, strontium, barium, yttrium, lanthanum, neodymium, praseodymium, niobium, silicon, tantalum, and combinations thereof.

44. The method of any one of claims 30 to 43, wherein the rare earth elements in the overcoat and washcoat layers are selected from the group consisting of praseodymium, cerium, neodymium, and combinations thereof.

45. The method of any one of claims 30 to 43, wherein the washcoat layer comprises lanthanum doped aluminum oxide (La-Al₂03) and a cerium based oxygen storage material (Ce-based OSM).