Ammonia oxidation catalyst with TWC functionality for gasoline applications

Abstract

The present invention relates to an exhaust gas treatment system for treating an exhaust gas stream exiting a gasoline engine, wherein said exhaust gas treatment system has an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, and wherein said exhaust gas treatment system comprises (i) a first catalyst, being a three-way conversion catalyst, having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material; (ii) a second catalyst, being a four-way conversion catalyst, having an inlet end and an outlet end and comprising a coating disposed on a wall flow filter substrate, wherein the coating comprises one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material; or a gasoline particle filter having an inlet end and an outlet end; (iii) a third catalyst having an inlet end and an outlet end, wherein the third catalyst comprises a substrate and a coating for the oxidation of ammonia (AMOx), as well as for the reduction of nitrogen oxide, the oxidation of carbon monoxide and the oxidation of hydrocarbons (TWC), wherein the coating of the third catalyst comprises one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material, wherein the coating of the third catalyst comprises one or more zeolitic materials, and wherein the coating of the third catalyst comprises rhodium and / or an oxygen storage compound; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst; wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst; wherein in the exhaust gas treatment system, the third catalyst according to (iii) is located downstream of the second catalyst according to (ii) and wherein the inlet end of the third catalyst is arranged upstream of the outlet end of the third catalyst.

Description

[0001] Ammonia oxidation catalyst with TWC functionality for gasoline applications

[0002] TECHNICAL FIELD

[0003] The present invention relates to an exhaust gas treatment system for treating an exhaust gas stream exiting a gasoline engine and a method for treating an exhaust gas stream exiting a gasoline engine using said exhaust gas treatment system.

[0004] INTRODUCTION

[0005] Emission regulations for exhaust gas from mobile gasoline applications have been increasingly stringent in the past and will presumably lead to even stricter regulations in the future. Accordingly, more effective exhaust gas treatment systems for automotives will be required in the coming years. Efficient ways of removing the main pollutants from gasoline engines including nitrogen oxides (NOx), unburned hydrocarbons (HC), carbon monoxide (CO) and particulate matter have been developed and commercialized in the past based on the so-called three way conversion catalysts (TWC) or four way conversion catalysts (FWC).

[0006] However, it is possible that future emission regulations could also impose stricter limits to secondary emissions from exhaust gas. For instance, more stringent European emission standards like EURO 7 or comparable regulations in the US may impose restrictions to ammonia (NH3), hydrocarbon (HC) and carbon monoxide (CO) tailpipe emissions, which have been shown to have a detrimental effect on humans, ecosystems and vegetation. Therefore, there is a need to provide improved exhaust gas treatment systems which permits to reduce the ammonia (NH3), hydrocarbon (HC) and carbon monoxide (CO) tailpipe emissions.

[0007] EP 3974059 A1 relates to a process for preparing a catalyst for the oxidation of ammonia, characterized by the following process steps: milling platinum black comprising primary particles of a particle size of 2 to 7 nm to a size of agglomerates of 30 to 150 nm and then mixing with a support material; or mixing platinum black comprising primary particles of a particle size of 2 to 7 nm with a support material and milling the mixture to a size of agglomerates of the platinum black of 30 to 150 nm; coating the mixture onto a carrier substrate.

[0008] EP 3310461 A1 relates to a catalyst article having an ammonia slip catalyst (ASC) comprising a blend of platinum on a support with low ammonia storage and a first SCR catalyst, and a second catalyst, such as a diesel oxidation catalyst, a diesel exotherm catalyst (DEC), a NOx absorber, a selective catalytic reduction / passive NOx adsorber (SCR / PNA), a cold-start catalyst (CSC) or a three-way catalyst (TWC).

[0009] DETAILED DESCRIPTION Therefore, it was an object of the present invention to provide an improved exhaust gas treatment system for treating an exhaust gas stream exiting a gasoline engine which permits to reduce the ammonia (NH3), hydrocarbon (HC) and / or carbon monoxide (CO) tailpipe emissions compared to systems according to the prior art such as, e.g., EURO 6 or other systems. In addition to improved ammonia tailpipe emissions, it was found that the system of the present invention contributes significantly to HC and CO emissions reduction.

[0010] Therefore, the present invention relates to an exhaust gas treatment system for treating an exhaust gas stream exiting a gasoline engine, wherein said exhaust gas treatment system has an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, and wherein said exhaust gas treatment system comprises

[0011] (i) a first catalyst, being a three-way conversion catalyst, having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material;

[0012] (ii) a second catalyst, being a four-way conversion catalyst, having an inlet end and an outlet end and comprising a coating disposed on a wall flow filter substrate, wherein the coating comprises one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material; or a gasoline particle filter having an inlet end and an outlet end;

[0013] (iii) a third catalyst having an inlet end and an outlet end, wherein the third catalyst comprises a substrate and a coating for the oxidation of ammonia (AMOx), as well as for the reduction of nitrogen oxide, the oxidation of carbon monoxide and the oxidation of hydrocarbons (TWC), wherein the coating of the third catalyst comprises one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material, wherein the coating of the third catalyst comprises one or more zeolitic materials, and wherein the coating of the third catalyst comprises rhodium and / or an oxygen storage compound; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst; wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst; wherein in the exhaust gas treatment system, the third catalyst according to (iii) is located downstream of the second catalyst according to (ii) and wherein the inlet end of the third catalyst is arranged upstream of the outlet end of the third catalyst.

[0014] It is preferred that the outlet end of the first catalyst according to (i) is in fluid communication with the inlet end of the second catalyst according to (ii) and wherein between the outlet end of the first catalyst according to (i) and the inlet end of the second catalyst according to (ii), no catalyst for treating the exhaust gas stream exiting the first catalyst is located in the exhaust gas treatment system.

[0015] It is preferred that the outlet end of the second catalyst according to (ii) is in fluid communication with the inlet end of the third catalyst according to (iii) and wherein between the outlet end of the second catalyst according to (ii) and the inlet end of the third catalyst according to (iii), no catalyst for treating the exhaust gas stream exiting the second catalyst is located in the exhaust gas treatment system.

[0016] It is preferred that the one or more platinum group metals of the coating of the first catalyst are selected from the group consisting of Pd, Rh, and mixtures thereof, preferably wherein the one or more platinum group metals of the coating of the first catalyst are Pd and Rh.

[0017] It is preferred that the coating of the first catalyst comprises the one or more platinum group metals at a loading, calculated as elemental platinum group metal, in the range of from 1 to 300 g / ft3, preferably in the range of from 10 to 290 g / ft3, more preferably in the range of from 30 to 270 g / ft3, more preferably in the range of from 50 to 260 g / ft3, more preferably in the range of from 60 to 250 g / ft3.

[0018] It is preferred that the support material supporting the platinum group metal component of the coating of the first catalyst is selected from the group consisting of alumina, ceria, silica, zirconia, titania, a mixture of two or more thereof and a mixed oxide of two or more thereof, preferably selected from the group consisting of alumina, titania, zirconia, a mixture of two or more thereof and a mixed oxide of two or more thereof, more preferably selected from the group consisting of alumina, zirconia, a mixture of two thereof, and a mixed oxide of two thereof, more preferably alumina.

[0019] It is preferred that the coating of the first catalyst further comprises an oxygen storage compound, the oxygen storage compound preferably comprises cerium, more preferably comprises one or more of a cerium oxide, a mixture of oxides comprising a cerium oxide and a mixed oxide comprising cerium, wherein the mixed oxide comprising cerium more preferably further comprises one or more of zirconium, yttrium, neodymium, lanthanum, hafnium, samarium and praseodymium, more preferably one or more of zirconium, yttrium, neodymium, lanthanum, and praseodymium, more preferably zirconium. In the case where the first catalyst further comprises an oxygen storage, it is preferred that the coating of the first catalyst comprises the oxygen storage compound at a loading in the range of from 0.1 to 10 g / in3, preferably in the range of from 0.5 to 5 g / in3, more preferably in the range of from 1 .0 to 3 g / in3, more preferably in the range of from 1 .3 to 2.7 g / in3, more preferably in the range of from 1 .5 to 2.5 g / in3. Yet further, it is preferred that in the coating of the first catalyst, the weight ratio of the support material relative to the oxygen storage compound is in the range of from 0.1 to 5 g / in3, preferably in the range of from 0.3 to 3 g / in3, more preferably in the range of from 0.5 to 2 g / in3, more preferably in the range of from 0.7 to 1 .7 g / in3, more preferably in the range of from 0.8 to 1 .5 g / in3. It is preferred that the coating of the first catalyst further comprises a non-zeolitic oxidic material, the non-zeolitic oxidic material preferably comprises one or more of zirconia, alumina, ceria, titania, silica, and a mixed oxide comprising two or more of Zr, Al, Ce, Ti, and Si, more preferably comprises one or more of zirconia, alumina, ceria and silica, more preferably comprises zirconia. Yet further, it is preferred that the coating of the first catalyst comprises the non-zeolitic oxidic material in an amount, calculated as the oxide, in the range of from 95 to 100 weight-%, preferably in the range of from 96 to 99.5 weight-%, more preferably in the range of from 97 to

[0020] 99 weight-%, based on the weight of the coating of the first catalyst.

[0021] It is preferred that the coating of the first catalyst further comprises an NOx storage component, preferably wherein the NOx storage component comprises one or more of an oxide of an alkaline earth metal and an oxide of an alkaline metal, more preferably wherein the NOx storage component comprises an oxide selected from the group consisting of Mg, Ca, Sr, Ba, Li, Na, K, Rb, and Cs, more preferably an oxide selected from the group consisting of Mg, Ca, Sr, and Ba, more preferably wherein the NOx storage component comprises, preferably consists of, barium oxide. Yet further, it is preferred that the coating of the first catalyst comprises the NOx storage component in an amount in the range of from 0.1 to 15 weight-%, preferably in the range of from 0.5 to 15 weight-%, more preferably in the range of from 1 to 10 weight-%, based on the weight of the coating of the first catalyst.

[0022] It is preferred that from 98 to 100 weight-%, preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-%, of the coating of the first catalyst consist of one or more platinum group metals supported on a support material, preferably an oxygen storage compound as defined in the foregoing, more preferably a non-zeolitic oxidic material as defined in the foregoing, and more preferably an NOx storage component as defined in the foregoing.

[0023] It is preferred that the substrate of the first catalyst is a flow through substrate, preferably a ceramic flow through substrate.

[0024] It is preferred the first catalyst consists of the substrate and the coating.

[0025] It is preferred that the one or more platinum group metals of the coating of the second catalyst is selected from the group consisting of Pd, Rh, and mixtures thereof, preferably wherein the one or more platinum group metals are Pd and Rh.

[0026] It is preferred that the coating of the second catalyst comprises the one or more platinum group metals at a loading, calculated as elemental platinum group metal, in the range of from 0.1 to

[0027] 100 g / ft3, preferably in the range of from 1 to 80 g / ft3, more preferably in the range of from 5 to 50 g / ft3, more preferably in the range of from 10 to 30 g / ft3. It is preferred that the support material supporting the platinum group metal component of the coating of the second catalyst is selected from the group consisting of alumina, ceria, silica, zirconia, titania, a mixture of two or more thereof and a mixed oxide of two or more thereof, preferably selected from the group consisting of alumina, titania, zirconia, a mixture of two or more thereof and a mixed oxide of two or more thereof, more preferably selected from the group consisting of alumina, zirconia, a mixture of two thereof, and a mixed oxide of two thereof, more preferably alumina.

[0028] It is preferred that the coating of the second catalyst further comprises an oxygen storage compound (OSC), the oxygen storage compound preferably comprises cerium, more preferably comprises one or more of a cerium oxide, a mixture of oxides comprising a cerium oxide and a mixed oxide comprising cerium, wherein the mixed oxide comprising cerium more preferably further comprises one or more of zirconium, yttrium, neodymium, lanthanum, hafnium, samarium and praseodymium, more preferably one or more of zirconium, yttrium, neodymium, lanthanum, and praseodymium, more preferably zirconium. In the case wherein the coating of the second catalyst further comprises an oxygen storage compound (OSC), it is preferred that the coating of the second catalyst comprises the oxygen storage compound at a loading in the range of from 0.1 to 5 g / in3, preferably in the range of from 0.1 to 2 g / in3, more preferably in the range of from 0.2 to 1 .5 g / in3, more preferably in the range of from 0.3 to 1 g / in3. Yet further, it is preferred that in the coating of the second catalyst, the weight ratio of the support material relative to the oxygen storage compound is in the range of from 0.1 to 5 g / in3, preferably in the range of from 0.2 to 3 g / in3, more preferably in the range of from 0.25 to 2 g / in3, more preferably in the range of from 0.3 to 1 g / in3.

[0029] It is preferred that the coating of the second catalyst further comprises a non-zeolitic oxidic material, the non-zeolitic oxidic material preferably comprises one or more of zirconia, alumina, ceria, titania, silica, and a mixed oxide comprising two or more of Zr, Al, Ce, Ti, and Si, more preferably comprises one or more of zirconia, alumina, ceria and silica, more preferably comprises zirconia; wherein the coating of the second catalyst preferably comprises the non-zeolitic oxidic material in an amount, calculated as the oxide, in the range of from 10 to 70 weight-%, preferably in the range of from 20 to 60 weight-%, more preferably in the range of from 30 to 50 weight- %, more preferably in the range of from 35 to 45 weight-%, based on the weight of the coating of the first catalyst.

[0030] It is preferred that the coating of the second catalyst further comprises an oxide of an alkaline earth metal, the alkaline earth metal preferably being selected from the group consisting of barium, strontium and magnesium, more preferably being selected from the group consisting of barium and strontium, more preferably being barium. Yet further, it is preferred that the coating of the second catalyst comprises the oxide of the alkaline earth metal in an amount in the range of from 0.1 to 20 weight-%, preferably in the range of from 1 to 15 weight-%, more preferably in the range of from 5 to 10 weight-%, based on the weight of the coating of the second catalyst. It is preferred that from 98 to 100 weight-%, preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-%, of the coating of the second catalyst consist of the one or more platinum group metals supported on a support material, preferably an oxygen storage compound as defined in the foregoing, more preferably a non-zeolitic oxidic material as defined in the foregoing, and more preferably an oxide of an alkaline earth metal as defined in the foregoing.

[0031] It is preferred that the substrate of the second catalyst is a honeycomb wall flow filter substrate.

[0032] It is preferred that the substrate of the second catalyst is a ceramic substrate, wherein the ceramic substrate preferably comprises, more preferably consists of, cordierite, cordierite-alpha- alumina, aluminum titanate, silicon carbide, silicon nitride, zircon mullite, spodumene, alumina- silica-magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, alpha-alumina, or aluminasilicate.

[0033] It is preferred that the second catalyst consists of the substrate and the coating.

[0034] In the case where the exhaust gas system comprises a gasoline particle filter, it is preferred that the gasoline particle filter is a wall flow filter, preferably a honeycomb wall flow filter. Yet further, it is preferred that the wall flow filter is a ceramic wall flow filter, wherein the ceramic wall flow filter comprises, preferably consists of, cordierite, cordierite-alpha-alumina, aluminum titanate, silicon carbide, silicon nitride, zircon mullite, spodumene, alumina-silica-magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, alpha-alumina, or aluminasilicate.

[0035] It is preferred that the one or more platinum group metals of the coating of the third catalyst are selected from the group consisting of Pt, Rh, and mixtures thereof, preferably wherein the one or more platinum group metals of the AMOx coating of the third catalyst is Rh.

[0036] Alternatively, it is preferred that the third catalyst is substantially free of palladium, preferably wherein the third catalyst comprises 0.1 g / ft3or less of palladium, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the third catalyst is free of palladium.

[0037] As a second alternative, it is preferred that the coating of the third catalyst is substantially free of palladium, preferably wherein the catalytic coating of the third catalyst comprises 0.1 g / ft3or less of palladium, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the catalytic coating of the third catalyst is free of palladium.

[0038] It is preferred that the loading of the coating of the third catalyst is in the range of from 0.1 to 20 g / in3, preferably in the range of from 1 to 15 g / in3, more preferably in the range of from 2.1 to 10 g / in3, more preferably in the range of from 2.15 to 9.5 g / in3, more preferably in the range of from 2.2 to 9 g / in3, more preferably in the range of from 2.2.5 to 8.5 g / in3, more preferably in the range of from 2.3 to 8 g / in3, more preferably in the range of from 2.35 to 7.5 g / in3, more preferably in the range of from 2.4 to 7 g / in3, more preferably in the range of from 2.45 to 6 g / in3, more preferably in the range of from 2.5 to 5 g / in3, more preferably in the range of from 3.0 to 4.5 g / in3.

[0039] It is preferred that the support material of the coating of the third catalyst is selected from the group consisting of titania, alumina, ceria, silica, zirconia, a mixture of two or more thereof and a mixed oxide of two or more thereof, preferably selected from the group consisting of titania, alumina and silica, more preferably is alumina. Yet further, it is preferred that the coating of the third catalyst comprises the support material in an amount in the range of from 0.1 to 5 g / in3, preferably in the range of from 0.4 to 3 g / in3, more preferably in the range of from 0.6 to 2 g / in3, more preferably in the range of from 0.8 to 1 .6 g / in3, more preferably in the range of from 0.85 to 1 .5 g / in3.

[0040] It is preferred that the coating of the third catalyst comprises an oxygen storage compound, preferably wherein the oxygen storage compound preferably comprises cerium, more preferably comprises one or more of a cerium oxide, a mixture of oxides comprising a cerium oxide and a mixed oxide comprising cerium, wherein the mixed oxide comprising cerium more preferably further comprises one or more of aluminum, zirconium, yttrium, neodymium, lanthanum, hafnium, samarium and praseodymium, more preferably one or more of aluminum, zirconium, yttrium, neodymium, lanthanum, and praseodymium, more preferably aluminum. Yet further, it is preferred that the cerium content of the oxygen storage compound in the coating of the third catalyst is in the range of from 5 to 81 .46 weight-%, preferably of from 10 to 80 weight-%, more preferably of from 20 to 75 weight-%, more preferably of from 30 to 70 weight-%, more preferably of from 40 to 60 weight-%, more preferably of from 45 to 55 weight-%, based on the total weight of the oxygen storage compound of the coating of the third catalyst.

[0041] Within the meaning of the present invention, the term „rare earth metal" refers to Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0042] It is preferred that the support material of the coating of the third catalyst comprises one or more rare earth metals, and wherein the one or more rare earth metals are selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, and mixtures of two or more thereof, preferably from the group consisting of La, Ce, and mixtures thereof, more preferably wherein the one or more rare earth metals is La.

[0043] In the case, wherein the support material of the coating of the third catalyst comprises one or more rare earth metals, it is preferred that the content of the one or more rare earth metals of the support material of the coating of the third catalyst is in the range of from 0.1 to 80 weight- %, preferably of from 0.5 to 70 weight-%, more preferably of from 1 to 60 weight-%, more preferably of from 3 to 50 weight-%, more preferably of from 5 to 40 weight-%, more preferably of from 10 to 30 weight-%, more preferably of from 15 to 25 weight-%, based on the total weight of the support material of the coating of the third catalyst. Alternatively, it is preferred that the one or more rare earth metals is lanthanum, and wherein the lanthanum content of the support material of the coating of the third catalyst is in an amount in the range of from 0.1 to 30 weight-%, preferably of from 0.5 to 20 weight-%, more preferably of from 1 to 15 weight-%, more preferably of from 1 .5 to 10 weight-%, more preferably of from 2 to 8 weight-%, more preferably of from 2.5 to 6 weight-%, more preferably of from 3 to 5 weight- %, more preferably of from 3.5 to 4.5 weight-%, based on the total weight of the support material of the coating of the third catalyst.

[0044] As a second alternative, it is preferred that the one or more rare earth metals is cerium, and wherein the cerium content of the support material of the coating of the third catalyst is in an amount in the range of from 1 to 80 weight-%, preferably of from 5 to 70 weight-%, more preferably of from 10 to 60 weight-%, more preferably of from 20 to 50 weight-%, more preferably of from 30 to 40 weight-%, based on the total weight of the support material of the coating of the third catalyst.

[0045] It is preferred that the one or more zeolitic materials comprised in the coating of the third catalyst comprise one or more of Fe and Cu, preferably wherein the one or more zeolitic materials comprise Fe. In the case, wherein the one or more zeolitic materials comprised in the coating of the third catalyst comprise one or more of Fe and Cu, it is preferred that the one or more zeolitic materials comprised in the coating of the third catalyst is a 12-membrered ring pore zeolitic material, wherein the 12-membered ring pore zeolitic material preferably has framework type selected from the group consisting of BEA, MOR, FAU, GME, OFF, a mixture of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of BEA, MOR, FAU, a mixture of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of BEA and FAU, wherein more preferably the 12-membered ring pore zeolitic material comprised in the coating of the third catalyst has a framework type BEA. Yet further, it is preferred that from 95 to 100 weight-%, preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, of the framework structure of the 12-membered ring pore zeolitic material comprised in the coating of the third catalyst consists of Si, Al, and O, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiC^AhOs, is more preferably in the range of from 2:1 to 40:1 , more preferably in the range of from 3:1 to 30:1 , more preferably in the range of from 4:1 to 20:1 , more preferably in the range of from 6:1 to 15:1.

[0046] It is preferred that the coating of the third catalyst extends over 98 to 100 %, more preferably over 99 to 100%, more preferably over 99.5 to 100%, of the substrate axial length.

[0047] It is preferred that the substrate of the third catalyst is a ceramic wall flow filter substrate.

[0048] Within the meaning of the present invention, the term „alkaline earth metal” refers to the elements Mg, Ca, Sr, and Ba, and the term “alkali metal” refers to the elements Li, Na, K, Rb, Cs and Fr. It is preferred that the coating of the third catalyst is substantially free of alkaline earth metal oxides and alkaline metal oxides, wherein preferably the coating comprises 0.1 g / ft3or less of alkaline earth metal oxides and alkaline metal oxides, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the coating of the third catalyst is free of alkaline earth metal oxides and alkaline metal oxides.

[0049] It is preferred that the coating of the third catalyst is substantially free of barium, wherein preferably the coating of the third catalyst comprises 0.1 g / ft3or less of barium, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the coating of the third catalyst is free of barium.

[0050] It is preferred that the coating of the third catalyst comprises a first catalytic coating comprising one or more platinum group metals supported on a support material, and a second catalytic coating comprising one or more zeolitic materials, wherein the first catalytic coating comprises rhodium and / or an oxygen storage compound.

[0051] In the case, wherein the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the one or more platinum group metals comprised in the first catalytic coating are selected from the group consisting of Pt, Rh, and mixtures thereof, more preferably wherein the one or more platinum group metals comprised in the first catalytic coating is Rh.

[0052] Yet further, it is preferred that the first catalytic coating is substantially free of palladium, preferably wherein the first catalytic coating comprises 0.1 g / ft3or less of palladium, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the first catalytic coating is free of palladium.

[0053] Yet further, it is preferred that the loading of the first catalytic coating is in the range of from 0.1 to 20 g / in3, preferably in the range of from 1 to 15 g / in3, more preferably in the range of from 2.1 to 10 g / in3, more preferably in the range of from 2.15 to 9.5 g / in3, more preferably in the range of from 2.2 to 9 g / in3, more preferably in the range of from 2.2.5 to 8.5 g / in3, more preferably in the range of from 2.3 to 8 g / in3, more preferably in the range of from 2.35 to 7.5 g / in3, more preferably in the range of from 2.4 to 7 g / in3, more preferably in the range of from 2.45 to 6 g / in3, more preferably in the range of from 2.5 to 5 g / in3, more preferably in the range of from 3.0 to 4.5 g / in3.

[0054] Yet further, it is preferred that the support material of the first catalytic coating is selected from the group consisting of titania, alumina, ceria, silica, zirconia, a mixture of two or more thereof and a mixed oxide of two or more thereof, preferably selected from the group consisting of titania, alumina and silica, more preferably is alumina. Yet further, it is preferred that the first catalytic coating comprises the support material in an amount in the range of from 0.1 to 5 g / in3, preferably in the range of from 1 to 3 g / in3, more preferably in the range of from 1.3 to 2.7 g / in3, more preferably in the range of from 1.5 to 2.5 g / in3.

[0055] Yet further, it is preferred that the first catalytic coating of the third catalyst comprises an oxygen storage compound, preferably wherein the oxygen storage compound preferably comprises cerium, more preferably comprises one or more of a cerium oxide, a mixture of oxides comprising a cerium oxide and a mixed oxide comprising cerium, wherein the mixed oxide comprising cerium more preferably further comprises one or more of aluminum, zirconium, yttrium, neodymium, lanthanum, hafnium, samarium and praseodymium, more preferably one or more of aluminum, zirconium, yttrium, neodymium, lanthanum, and praseodymium, more preferably aluminum.

[0056] In the case where the oxygen storage compound comprises cerium, it is preferred that the cerium content of the oxygen storage compound in the coating of the third catalyst is in the range of from 5 to 81.46 weight-%, preferably of from 10 to 80 weight-%, more preferably of from 20 to 75 weight-%, more preferably of from 30 to 70 weight-%, more preferably of from 40 to 60 weight-%, more preferably of from 45 to 55 weight-%, based on the total weight of the oxygen storage compound of the coating of the third catalyst.

[0057] In the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the support material of the first catalytic coating of the third catalyst comprises one or more rare earth metals, and wherein the one or more rare earth metals are selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, and mixtures of two or more thereof, preferably from the group consisting of La, Ce, and mixtures thereof, more preferably wherein the one or more rare earth metals is La.

[0058] In the case where the support material of the first catalytic coating of the third catalyst comprises one or more rare earth metals, it is preferred that the content of the one or more rare earth metals of the support material of the first catalytic coating is in the range of from 0.1 to 80 weight-%, preferably of from 0.5 to 70 weight-%, more preferably of from 1 to 60 weight-%, more preferably of from 3 to 50 weight-%, more preferably of from 5 to 40 weight-%, more preferably of from 10 to 30 weight-%, more preferably of from 15 to 25 weight-%, based on the total weight of the support material of the first catalytic coating of the third catalyst.

[0059] Alternatively, it is preferred that the one or more rare earth metals is lanthanum, and wherein the lanthanum content of the support material of the first catalytic coating is in an amount in the range of from 0.1 to 30 weight-%, preferably of from 0.5 to 20 weight-%, more preferably of from 1 to 15 weight-%, more preferably of from 1.5 to 10 weight-%, more preferably of from 2 to 8 weight-%, more preferably of from 2.5 to 6 weight-%, more preferably of from 3 to 5 weight-%, more preferably of from 3.5 to 4.5 weight-%, based on the total weight of the support material of the first catalytic coating of the third catalyst. io As a second alternative, it is preferred that the one or more rare earth metals is cerium, and wherein the cerium content of the support material of the first catalytic coating is in an amount in the range of from 1 to 80 weight-%, preferably of from 5 to 70 weight-%, more preferably of from 10 to 60 weight-%, more preferably of from 20 to 50 weight-%, more preferably of from 30 to 40 weight-%, based on the total weight of the support material of the first catalytic coating of the third catalyst.

[0060] In the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the first catalytic coating is substantially free of zeolitic material, preferably wherein the first catalytic coating comprises 0.1 g / ft3or less of zeolitic material, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the first catalytic coating is free of zeolitic material.

[0061] Yet further, in the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the first catalytic coating is free of zeolitic material and wherein the zeolitic material comprised in the AMOx coating is comprised entirely in the second catalytic coating.

[0062] Yet further, in the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the first catalytic coating is substantially free of alkaline earth metal oxides and alkaline metal oxides, wherein preferably the ammonia oxidation coating comprises 0.1 g / ft3or less of alkaline earth metal oxides and alkaline metal oxides, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the ammonia oxidation coating of the third catalyst is free of alkaline earth metal oxides and alkaline metal oxides.

[0063] Yet further, in the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the first catalytic coating is substantially free of barium, wherein preferably the ammonia oxidation coating comprises 0.1 g / ft3or less of barium, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the first catalytic coating is free of barium.

[0064] Yet further, in the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the zeolitic material comprised in the second catalytic coating is selected from the group consisting of AFR, ATS, BEA, DFO, EMT, EON, FAU, GME, IWS, IWV, MEI, MSE, MOR, OFF, POS, SAO, SBE, SBS, SBT, SOR, SOV, and mixtures of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of AFR, BEA, DFO, EON, GME, IWS, IWV, MOR, OFF, SBE, SBS, SBT, and mixtures of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of BEA, MOR, OFF, and mixtures of two or more thereof and a mixed type of two or more thereof, wherein more preferably the 12-membered ring pore zeolitic material comprised in the second catalytic coating of the third catalyst has a framework type BEA. Yet further, in the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that from 95 to 100 weight-%, preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, of the framework structure of the 12-membered ring pore zeolitic material comprised in the second catalytic coating consists of Si, Al, and O, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiC^AhOs, is more preferably in the range of from 1 to 100, more preferably in the range of from 3 to 50, more preferably in the range of from 5 to 20, more preferably in the range of from 7 to 15, more preferably in the range of from 7.5 to 12.5.

[0065] Yet further, in the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the zeolitic material comprised in the second catalytic coating comprises iron, wherein the amount of iron comprised in the zeolitic material, calculated as Fe2Os, is preferably in the range of from 0.1 to 10.0 weight-%, more preferably in the range of from 0.5 to 8 weight-%, more preferably in the range of from 1.5 to 7.5 weight-%, based on the total weight of the zeolitic material.

[0066] Yet further, in the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the second catalytic coating is substantially free of Cu, preferably wherein the second catalytic coating comprises 0.1 weight-% or less of Cu, more preferably 0.01 weight-% or less, more preferably 0.001 weight-% or less, more preferably wherein the second catalytic coating of the third catalyst is free of Cu.

[0067] Yet further, in the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the second catalytic coating further comprises a non-zeolitic oxidic material, wherein the non-zeolitic oxidic material is selected from the group consisting of zirconia, alumina, ceria, titania, silica, and mixtures of two or more thereof, preferably from the group consisting of zirconia, alumina, ceria, silica, and mixtures of two or more thereof, more preferably from the group consisting of zirconia, alumina, or mixtures thereof, more preferably wherein the non-zeolitic oxidic material is zirconia and alumina.

[0068] In the case wherein the second catalytic coating further comprises a non-zeolitic oxidic material, it is preferred that the second catalytic coating comprises the non-zeolitic oxidic material in an amount, calculated as the oxide, in the range of from 0.5 to 12 weight-%, preferably in the range of from 1 to 10 weight-%, more preferably in the range of from 1 to 6 weight-%, based on the washcoat loading of the second catalytic coating.

[0069] In the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the second catalytic coating is substantially free of ceria, preferably wherein the second catalytic coating comprises 0.1 weight-% or less of ceria, more preferably 0.01 weight-% or less, more preferably 0.001 weight-% or less, more preferably wherein the second catalytic coating is free of ceria. Yet further, in the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the second catalytic coating is substantially free of platinum group metals, preferably wherein the second catalytic coating comprises 0.1 weight-% or less of platinum group metals, more preferably 0.01 weight-% or less, more preferably 0.001 weight-% or less, more preferably wherein the second catalytic coating is free of platinum group metals.

[0070] Yet further, in the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the second catalytic coating is free of platinum group metals and wherein the one or more platinum group metals comprised in the AMOx coating are comprised entirely in the first catalytic coating.

[0071] Yet further, in the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the loading of the second catalytic coating is in the range of from 0.1 to 20 g / in3, preferably in the range of from 1 to 15 g / in3, more preferably in the range of from 2 to 10 g / in3, more preferably in the range of from 2.5 to 8 g / in3, more preferably in the range of from 3 to 6 g / in3, more preferably in the range of from 3.05 to 5.5 g / in3, more preferably in the range of from 3.1 to 5 g / in3, more preferably in the range of from 3.15 to 4.5 g / in3, more preferably in the range of from 3.2 to 4 g / in3, more preferably in the range of from 3.25 to 3.75 g / in3, more preferably in the range of from 3.3 to 3.5 g / in3.

[0072] In the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that from 98 to 100 weight-%, preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight- %, of the second catalytic coating consists of a zeolitic material comprising one or more of Fe and Cu, and preferably a non-zeolitic oxidic material as defined in the foregoing.

[0073] Yet further, in the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that the first catalytic coating is disposed on the substrate of the third catalyst over 98 to 100 %, preferably 99 to 100%, more preferably 99.5 to 100%, of the substrate axial length, and the second catalytic coating is disposed on the first catalytic coating over 98 to 100 %, preferably 99 to 100%, more preferably 99.5 to 100%, of the substrate axial length.

[0074] Alternatively, it is preferred that the third catalyst comprises an inlet zone comprising, preferably consisting of, the first catalytic coating and an outlet zone comprising, preferably consisting of, a second catalytic coating.

[0075] In the case where the third catalyst comprises an inlet zone comprising the first catalytic coating and an oulet zone comprising a second catalytic coating, it is preferred that the inlet zone extends over x % of the substrate axial length from the inlet end towards the outlet end of the sub- strate, with x is in the range of from 20 to 60, preferably in the range of from 30 to 55, more preferably in the range of from 45 to 55. Yet further, it is preferred that the outlet zone extends over y % of the substrate axial length, with y = 100 - x, from the outlet end towards the inlet end of the substrate. Yet further, it is preferred that the second catalytic coating is disposed on the substrate of the third catalyst over 50% of the substrate axial length, forming the inlet zone. Yet further, it is preferred that the first catalytic coating is disposed on the substrate of the third catalyst over 50% of the substrate axial length.

[0076] In the case where the coating of the third catalyst comprises a first catalytic coating and a second catalytic coating, it is preferred that from 98 to 100 weight-%, preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight- %, of the first catalytic coating of the third catalyst consists of one or more platinum group metals, a support material supporting the platinum group metal and one or more rare earth metals comprised in the support material.

[0077] It is preferred that the third catalyst consists of the substrate and the AMOx coating.

[0078] The present invention further refers to a method for the simultaneous selective catalytic reduction of NOx, the oxidation of a hydrocarbon, the oxidation of nitrogen monoxide, and the oxidation of ammonia, comprising

[0079] (1 ) providing an exhaust gas stream from a gasoline engine comprising one or more of NOx, ammonia, nitrogen monoxide and a hydrocarbon;

[0080] (2) passing the exhaust gas stream provided in (1) through the exhaust gas system according to any one of the embodiments disclosed herein.

[0081] The present invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. In particular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as “The exhaust gas treatment system of any one of embodiments 1 to 4”, every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to “The exhaust gas treatment system of any of embodiments 1 , 2, 3, and 4”.

[0082] Further, it is explicitly noted that the following set of embodiments represents a suitably structured part of the general description directed to preferred aspects of the present invention, and, thus, suitably supports, but does not represent the claims of the present invention.

[0083] 1 . An exhaust gas treatment system for treating an exhaust gas stream exiting a gasoline engine, wherein said exhaust gas treatment system has an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, and wherein said exhaust gas treatment system comprises (i) a first catalyst, being a three-way conversion catalyst, having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material;

[0084] (ii) a second catalyst, being a four-way conversion catalyst, having an inlet end and an outlet end and comprising a coating disposed on a wall flow filter substrate, wherein the coating comprises one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material; or a gasoline particle filter having an inlet end and an outlet end;

[0085] (iii) a third catalyst having an inlet end and an outlet end, wherein the third catalyst comprises a substrate and a coating for the oxidation of ammonia (AMOx), as well as for the reduction of nitrogen oxide, the oxidation of carbon monoxide and the oxidation of hydrocarbons (TWC), wherein the coating of the third catalyst comprises one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material, wherein the coating of the third catalyst comprises one or more zeolitic materials, and wherein the coating of the third catalyst comprises rhodium and / or an oxygen storage compound; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst; wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst; wherein in the exhaust gas treatment system, the third catalyst according to (iii) is located downstream of the second catalyst according to (ii) and wherein the inlet end of the third catalyst is arranged upstream of the outlet end of the third catalyst.

[0086] 2. The exhaust gas treatment system of embodiment 1 , wherein the outlet end of the first catalyst according to (i) is in fluid communication with the inlet end of the second catalyst according to (ii) and wherein between the outlet end of the first catalyst according to (i) and the inlet end of the second catalyst according to (ii), no catalyst for treating the exhaust gas stream exiting the first catalyst is located in the exhaust gas treatment system.

[0087] 3. The exhaust gas treatment system of embodiment 1 or 2, wherein the outlet end of the second catalyst according to (ii) is in fluid communication with the inlet end of the third catalyst according to (iii) and wherein between the outlet end of the second catalyst according to (ii) and the inlet end of the third catalyst according to (iii), no catalyst for treating the exhaust gas stream exiting the second catalyst is located in the exhaust gas treatment system.

[0088] 4. The exhaust gas treatment system of any one of embodiments 1 to 3, wherein the one or more platinum group metals of the coating of the first catalyst are selected from the group consisting of Pd, Rh, and mixtures thereof, preferably wherein the one or more platinum group metals of the coating of the first catalyst are Pd and Rh.

[0089] 5. The exhaust gas treatment system of any one of embodiments 1 to 4, wherein the coating of the first catalyst comprises the one or more platinum group metals at a loading, calculated as elemental platinum group metal, in the range of from 1 to 300 g / ft3, preferably in the range of from 10 to 290 g / ft3, more preferably in the range of from 30 to 270 g / ft3, more preferably in the range of from 50 to 260 g / ft3, more preferably in the range of from 60 to 250 g / ft3.

[0090] 6. The exhaust gas treatment system of any one of embodiments 1 to 5, wherein the support material supporting the platinum group metal component of the coating of the first catalyst is selected from the group consisting of alumina, ceria, silica, zirconia, titania, a mixture of two or more thereof and a mixed oxide of two or more thereof, preferably selected from the group consisting of alumina, titania, zirconia, a mixture of two or more thereof and a mixed oxide of two or more thereof, more preferably selected from the group consisting of alumina, zirconia, a mixture of two thereof, and a mixed oxide of two thereof, more preferably alumina.

[0091] 7. The exhaust gas treatment system of any one of embodiments 1 to 6, wherein the coating of the first catalyst further comprises an oxygen storage compound, the oxygen storage compound preferably comprises cerium, more preferably comprises one or more of a cerium oxide, a mixture of oxides comprising a cerium oxide and a mixed oxide comprising cerium, wherein the mixed oxide comprising cerium more preferably further comprises one or more of zirconium, yttrium, neodymium, lanthanum, hafnium, samarium and praseodymium, more preferably one or more of zirconium, yttrium, neodymium, lanthanum, and praseodymium, more preferably zirconium.

[0092] 8. The exhaust gas treatment system of embodiments 7, wherein the coating of the first catalyst comprises the oxygen storage compound at a loading in the range of from 0.1 to 10 g / in3, preferably in the range of from 0.5 to 5 g / in3, more preferably in the range of from 1 .0 to 3 g / in3, more preferably in the range of from 1.3 to 2.7 g / in3, more preferably in the range of from 1.5 to 2.5 g / in3.

[0093] 9. The exhaust gas treatment system of embodiment 7 or 8, wherein, in the coating of the first catalyst, the weight ratio of the support material relative to the oxygen storage compound is in the range of from 0.1 to 5 g / in3, preferably in the range of from 0.3 to 3 g / in3, more preferably in the range of from 0.5 to 2 g / in3, more preferably in the range of from 0.7 to 1.7 g / in3, more preferably in the range of from 0.8 to 1 .5 g / in3.

[0094] 10. The exhaust gas treatment system of any of embodiments 1 to 9, wherein the coating of the first catalyst further comprises a non-zeolitic oxidic material, the non-zeolitic oxidic material preferably comprises one or more of zirconia, alumina, ceria, titania, silica, and a mixed oxide comprising two or more of Zr, Al, Ce, Ti, and Si, more preferably comprises one or more of zirconia, alumina, ceria and silica, more preferably comprises zirconia.

[0095] 11 . The exhaust gas treatment system of embodiment 10, wherein the coating of the first catalyst comprises the non-zeolitic oxidic material in an amount, calculated as the oxide, in the range of from 95 to 100 weight-%, preferably in the range of from 96 to 99.5 weight-%, more preferably in the range of from 97 to 99 weight-%, based on the weight of the coating of the first catalyst.

[0096] 12. The exhaust gas treatment system of any of embodiments 1 to 11 , wherein the coating of the first catalyst further comprises an NOx storage component, preferably wherein the NOx storage component comprises one or more of an oxide of an alkaline earth metal and an oxide of an alkaline metal, more preferably wherein the NOx storage component comprises an oxide selected from the group consisting of Mg, Ca, Sr, Ba, Li, Na, K, Rb, and Cs, more preferably an oxide selected from the group consisting of Mg, Ca, Sr, and Ba, more preferably wherein the NOx storage component comprises, preferably consists of, barium oxide.

[0097] 13. The exhaust gas treatment system of embodiment 12, wherein the coating of the first catalyst comprises the NOx storage component in an amount in the range of from 0.1 to 15 weight-%, preferably in the range of from 0.5 to 15 weight-%, more preferably in the range of from 1 to 10 weight-%, based on the weight of the coating of the first catalyst.

[0098] 14. The exhaust gas treatment system of any one of embodiments 1 to 6 wherein from 98 to

[0099] 100 weight-%, preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight- %, more preferably from 99.9 to 100 weight-%, of the coating of the first catalyst consists of one or more platinum group metals supported on a support material, preferably an oxygen storage compound as defined in any one of embodiment 7 or 8, more preferably a non-zeo- litic oxidic material as defined in embodiment 10 or 11 , and more preferably an NOx storage component as defined in embodiment 12 or 13.

[0100] 15. The exhaust gas treatment system of any one of embodiments 1 to 14, wherein the substrate of the first catalyst is a flow through substrate, preferably a ceramic flow through substrate.

[0101] 16. The exhaust gas treatment system of any one of embodiments 1 to 15, wherein the first catalyst consists of the substrate and the coating.

[0102] 17. The exhaust gas treatment system of any one of embodiments 1 to 16, wherein the one or more platinum group metals of the coating of the second catalyst is selected from the group consisting of Pd, Rh, and mixtures thereof, preferably wherein the one or more platinum group metals are Pd and Rh. 18. The exhaust gas treatment system of any one of embodiments 1 to 17, wherein the coating of the second catalyst comprises the one or more platinum group metals at a loading, calculated as elemental platinum group metal, in the range of from 0.1 to 100 g / ft3, preferably in the range of from 1 to 80 g / ft3, more preferably in the range of from 5 to 50 g / ft3, more preferably in the range of from 10 to 30 g / ft3.

[0103] 19. The exhaust gas treatment system of any one of embodiments 1 to 18, wherein the support material supporting the platinum group metal component of the coating of the second catalyst is selected from the group consisting of alumina, ceria, silica, zirconia, titania, a mixture of two or more thereof and a mixed oxide of two or more thereof, preferably selected from the group consisting of alumina, titania, zirconia, a mixture of two or more thereof and a mixed oxide of two or more thereof, more preferably selected from the group consisting of alumina, zirconia, a mixture of two thereof, and a mixed oxide of two thereof, more preferably alumina.

[0104] 20. The exhaust gas treatment system of any one of embodiments 1 to 19, wherein the coating of the second catalyst further comprises an oxygen storage compound (OSC), the oxygen storage compound preferably comprises cerium, more preferably comprises one or more of a cerium oxide, a mixture of oxides comprising a cerium oxide and a mixed oxide comprising cerium, wherein the mixed oxide comprising cerium more preferably further comprises one or more of zirconium, yttrium, neodymium, lanthanum, hafnium, samarium and praseodymium, more preferably one or more of zirconium, yttrium, neodymium, lanthanum, and praseodymium, more preferably zirconium.

[0105] 21 . The exhaust gas treatment system of embodiment 20, wherein the coating of the second catalyst comprises the oxygen storage compound at a loading in the range of from 0.1 to 5 g / in3, preferably in the range of from 0.1 to 2 g / in3, more preferably in the range of from 0.2 to 1 .5 g / in3, more preferably in the range of from 0.3 to 1 g / in3.

[0106] 22. The exhaust gas treatment system of embodiment 20 or 21 , wherein, in the coating of the second catalyst, the weight ratio of the support material relative to the oxygen storage compound is in the range of from 0.1 to 5 g / in3, preferably in the range of from 0.2 to 3 g / in3, more preferably in the range of from 0.25 to 2 g / in3, more preferably in the range of from 0.3 to 1 g / in3.

[0107] 23. The exhaust gas treatment system of any of embodiments 1 to 22, wherein the coating of the second catalyst further comprises a non-zeolitic oxidic material, the non-zeolitic oxidic material preferably comprises one or more of zirconia, alumina, ceria, titania, silica, and a mixed oxide comprising two or more of Zr, Al, Ce, Ti, and Si, more preferably comprises one or more of zirconia, alumina, ceria and silica, more preferably comprises zirconia; wherein the coating of the second catalyst preferably comprises the non-zeolitic oxidic material in an amount, calculated as the oxide, in the range of from 10 to 70 weight-%, preferably in the range of from 20 to 60 weight-%, more preferably in the range of from 30 to 50 weight-%, more preferably in the range of from 35 to 45 weight-%, based on the weight of the coating of the first catalyst.

[0108] 24. The exhaust gas treatment system of any of embodiments 1 to 23, wherein the coating of the second catalyst further comprises an oxide of an alkaline earth metal, the alkaline earth metal preferably being selected from the group consisting of barium, strontium and magnesium, more preferably being selected from the group consisting of barium and strontium, more preferably being barium.

[0109] 25. The exhaust gas treatment system of embodiment 24, wherein the coating of the second catalyst comprises the oxide of the alkaline earth metal in an amount in the range of from 0.1 to 20 weight-%, preferably in the range of from 1 to 15 weight-%, more preferably in the range of from 5 to 10 weight-%, based on the weight of the coating of the second catalyst.

[0110] 26. The exhaust gas treatment system of any one of embodiments 1 to 19, wherein from 98 to

[0111] 100 weight-%, preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight- %, more preferably from 99.9 to 100 weight-%, of the coating of the second catalyst consist of the one or more platinum group metals supported on a support material, preferably an oxygen storage compound as defined in the foregoing, more preferably a non-zeolitic oxidic material as defined in the foregoing, and more preferably an oxide of an alkaline earth metal as defined in the foregoing.

[0112] 27. The exhaust gas treatment system of any one of embodiments 1 to 26, wherein the substrate of the second catalyst is a honeycomb wall flow filter substrate.

[0113] 28. The exhaust gas treatment system of any of claims 1 to 27, wherein the substrate of the second catalyst is a ceramic substrate, wherein the ceramic substrate preferably comprises, more preferably consists of, cordierite, cordierite-alpha-alumina, aluminum titanate, silicon carbide, silicon nitride, zircon mullite, spodumene, alumina-silica-magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, alpha-alumina, or aluminasilicate.

[0114] 29. The exhaust gas treatment system of any one of embodiments 1 to 28 wherein the second catalyst consists of the substrate and the coating.

[0115] 30. The exhaust gas treatment system of any one of claims 1 to 16, wherein the gasoline particle filter is a wall flow filter, preferably a honeycomb wall flow filter.

[0116] 31 . The exhaust gas treatment system of claim 30, wherein the wall flow filter is a ceramic wall flow filter, wherein the ceramic wall flow filter comprises, preferably consists of, cordierite, cordierite-alpha-alumina, aluminum titanate, silicon carbide, silicon nitride, zircon mullite, spodumene, alumina-silica-magnesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, alpha-alumina, or aluminasilicate. The exhaust gas treatment system of any one of embodiments 1 to 31 , wherein the one or more platinum group metals of the coating of the third catalyst are selected from the group consisting of Pt, Rh, and mixtures thereof, preferably wherein the one or more platinum group metals of the AMOx coating of the third catalyst is Rh. The exhaust gas treatment system of any one of embodiments 1 to 31 , wherein the third catalyst is substantially free of palladium, preferably wherein the third catalyst comprises 0.1 g / ft3or less of palladium, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the third catalyst is free of palladium. The exhaust gas treatment system of any one of embodiments 1 to 31 , wherein the coating of the third catalyst is substantially free of palladium, preferably wherein the catalytic coating of the third catalyst comprises 0.1 g / ft3or less of palladium, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the catalytic coating of the third catalyst is free of palladium. The exhaust gas treatment system of any one of embodiments 1 to 34, wherein the loading of the coating of the third catalyst is in the range of from 0.1 to 20 g / in3, preferably in the range of from 1 to 15 g / in3, more preferably in the range of from 2.1 to 10 g / in3, more preferably in the range of from 2.15 to 9.5 g / in3, more preferably in the range of from 2.2 to 9 g / in3, more preferably in the range of from 2.2.5 to 8.5 g / in3, more preferably in the range of from 2.3 to 8 g / in3, more preferably in the range of from 2.35 to 7.5 g / in3, more preferably in the range of from 2.4 to 7 g / in3, more preferably in the range of from 2.45 to 6 g / in3, more preferably in the range of from 2.5 to 5 g / in3, more preferably in the range of from 3.0 to 4.5 g / in3. The exhaust gas treatment system of any one of embodiments 1 to 35, wherein the support material of the coating of the third catalyst is selected from the group consisting of titania, alumina, ceria, silica, zirconia, a mixture of two or more thereof and a mixed oxide of two or more thereof, preferably selected from the group consisting of titania, alumina and silica, more preferably is alumina. The exhaust gas treatment system of embodiment 36, wherein the coating of the third catalyst comprises the support material in an amount in the range of from 0.1 to 5 g / in3, preferably in the range of from 0.4 to 3 g / in3, more preferably in the range of from 0.6 to 2 g / in3, more preferably in the range of from 0.8 to 1.6 g / in3, more preferably in the range of from 0.85 to 1 .5 g / in3. The exhaust gas treatment system of any one of embodiments 1 to 37, wherein the coating of the third catalyst comprises an oxygen storage compound, preferably wherein the oxygen storage compound preferably comprises cerium, more preferably comprises one or more of a cerium oxide, a mixture of oxides comprising a cerium oxide and a mixed oxide comprising cerium, wherein the mixed oxide comprising cerium more preferably further comprises one or more of aluminum, zirconium, yttrium, neodymium, lanthanum, hafnium, samarium and praseodymium, more preferably one or more of aluminum, zirconium, yttrium, neodymium, lanthanum, and praseodymium, more preferably aluminum.

[0117] 39. The exhaust gas treatment system of embodiment 38, wherein the cerium content of the oxygen storage compound in the coating of the third catalyst is in the range of from 5 to 81.46 weight-%, preferably of from 10 to 80 weight-%, more preferably of from 20 to 75 weight-%, more preferably of from 30 to 70 weight-%, more preferably of from 40 to 60 weight-%, more preferably of from 45 to 55 weight-%, based on the total weight of the oxygen storage compound of the coating of the third catalyst.

[0118] 40. The exhaust gas treatment system of any one of embodiments 1 to 39, wherein the support material of the coating of the third catalyst comprises one or more rare earth metals, and wherein the one or more rare earth metals are selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, and mixtures of two or more thereof, preferably from the group consisting of La, Ce, and mixtures thereof, more preferably wherein the one or more rare earth metals is La.

[0119] 41 . The exhaust gas treatment system of embodiment 40, wherein the content of the one or more rare earth metals of the support material of the coating of the third catalyst is in the range of from 0.1 to 80 weight-%, preferably of from 0.5 to 70 weight-%, more preferably of from 1 to 60 weight-%, more preferably of from 3 to 50 weight-%, more preferably of from 5 to 40 weight-%, more preferably of from 10 to 30 weight-%, more preferably of from 15 to 25 weight-%, based on the total weight of the support material of the coating of the third catalyst.

[0120] 42. The exhaust gas treatment system of embodiment 40, wherein the one or more rare earth metals is lanthanum, and wherein the lanthanum content of the support material of the coating of the third catalyst is in an amount in the range of from 0.1 to 30 weight-%, preferably of from 0.5 to 20 weight-%, more preferably of from 1 to 15 weight-%, more preferably of from

[0121] 1 .5 to 10 weight-%, more preferably of from 2 to 8 weight-%, more preferably of from 2.5 to 6 weight-%, more preferably of from 3 to 5 weight-%, more preferably of from 3.5 to 4.5 weight-%, based on the total weight of the support material of the coating of the third catalyst.

[0122] 43. The exhaust gas treatment system of embodiment 40, wherein the one or more rare earth metals is cerium, and wherein the cerium content of the support material of the coating of the third catalyst is in an amount in the range of from 1 to 80 weight-%, preferably of from 5 to 70 weight-%, more preferably of from 10 to 60 weight-%, more preferably of from 20 to 50 weight-%, more preferably of from 30 to 40 weight-%, based on the total weight of the support material of the coating of the third catalyst. 44. The exhaust gas treatment system of any one of embodiments 1 to 43, wherein the one or more zeolitic materials comprised in the coating of the third catalyst comprise one or more of Fe and Cu, preferably wherein the one or more zeolitic materials comprise Fe.

[0123] 45. The exhaust gas treatment system of embodiment 44, wherein the one or more zeolitic materials comprised in the coating of the third catalyst is a 12-membrered ring pore zeolitic material, wherein the 12-membered ring pore zeolitic material preferably has framework type selected from the group consisting of BEA, MOR, FAU, GME, OFF, a mixture of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of BEA, MOR, FAU, a mixture of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of BEA and FAU, wherein more preferably the 12-membered ring pore zeolitic material comprised in the coating of the third catalyst has a framework type BEA.

[0124] 46. The exhaust gas treatment system of embodiment 44 or 45, wherein from 95 to 100 weight- %, preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, of the framework structure of the 12-membered ring pore zeolitic material comprised in the coating of the third catalyst consists of Si, Al, and O, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO2:AhO3, is more preferably in the range of from 2:1 to 40:1 , more preferably in the range of from 3:1 to 30:1 , more preferably in the range of from 4:1 to 20:1 , more preferably in the range of from 6: 1 to 15: 1 .

[0125] 47. The exhaust gas treatment system of any one of embodiments 1 to 46, wherein the coating of the third catalyst extends over 98 to 100 %, more preferably over 99 to 100%, more preferably over 99.5 to 100%, of the substrate axial length.

[0126] 48. The exhaust gas treatment system of any one of embodiments 1 to 47, wherein the substrate of the third catalyst is a ceramic wall flow filter substrate.

[0127] 49. The exhaust gas treatment system of any one of embodiments 1 to 48, wherein coating of the third catalyst is substantially free of alkaline earth metal oxides and alkaline metal oxides, wherein preferably the coating comprises 0.1 g / ft3or less of alkaline earth metal oxides and alkaline metal oxides, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the coating of the third catalyst is free of alkaline earth metal oxides and alkaline metal oxides.

[0128] 50. The exhaust gas treatment system of any one of embodiments 1 to 49, wherein the coating of the third catalyst is substantially free of barium, wherein preferably the coating of the third catalyst comprises 0.1 g / ft3or less of barium, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the coating of the third catalyst is free of barium. The exhaust gas treatment system of any one of embodiments 1 to 50, wherein the coating of the third catalyst comprises a first catalytic coating comprising one or more platinum group metals supported on a support material, and a second catalytic coating comprising one or more zeolitic materials, wherein the first catalytic coating comprises rhodium and / or an oxygen storage compound. The exhaust gas treatment system of embodiment 51 , wherein the one or more platinum group metals comprised in the first catalytic coating are selected from the group consisting of Pt, Rh, and mixtures thereof, more preferably wherein the one or more platinum group metals comprised in the first catalytic coating is Rh. The exhaust gas treatment system of embodiment 51 or 52, wherein the first catalytic coating is substantially free of palladium, preferably wherein the first catalytic coating comprises 0.1 g / ft3or less of palladium, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the first catalytic coating is free of palladium. The exhaust gas treatment system of any one of embodiments 51 to 53, wherein the loading of the first catalytic coating is in the range of from 0.1 to 20 g / in3, preferably in the range of from 1 to 15 g / in3, more preferably in the range of from 2.1 to 10 g / in3, more preferably in the range of from 2.15 to 9.5 g / in3, more preferably in the range of from 2.2 to 9 g / in3, more preferably in the range of from 2.2.5 to 8.5 g / in3, more preferably in the range of from 2.3 to 8 g / in3, more preferably in the range of from 2.35 to 7.5 g / in3, more preferably in the range of from 2.4 to 7 g / in3, more preferably in the range of from 2.45 to 6 g / in3, more preferably in the range of from 2.5 to 5 g / in3, more preferably in the range of from 3.0 to 4.5 g / in3. The exhaust gas treatment system of any one of embodiments 51 to 54, wherein the support material of the first catalytic coating is selected from the group consisting of titania, alumina, ceria, silica, zirconia, a mixture of two or more thereof and a mixed oxide of two or more thereof, preferably selected from the group consisting of titania, alumina and silica, more preferably is alumina. The exhaust gas treatment system of any one of embodiments 51 to 55, wherein the first catalytic coating comprises the support material in an amount in the range of from 0.1 to 5 g / in3, preferably in the range of from 1 to 3 g / in3, more preferably in the range of from 1 .3 to 2.7 g / in3, more preferably in the range of from 1.5 to 2.5 g / in3. The exhaust gas treatment system of any one of embodiments 51 to 56, wherein the first catalytic coating of the third catalyst comprises an oxygen storage compound, preferably wherein the oxygen storage compound preferably comprises cerium, more preferably comprises one or more of a cerium oxide, a mixture of oxides comprising a cerium oxide and a mixed oxide comprising cerium, wherein the mixed oxide comprising cerium more preferably further comprises one or more of aluminum, zirconium, yttrium, neodymium, lanthanum, hafnium, samarium and praseodymium, more preferably one or more of aluminum, zirconium, yttrium, neodymium, lanthanum, and praseodymium, more preferably aluminum.

[0129] 58. The exhaust gas treatment system of embodiment 57, wherein the cerium content of the oxygen storage compound in the coating of the third catalyst is in the range of from 5 to 81.46 weight-%, preferably of from 10 to 80 weight-%, more preferably of from 20 to 75 weight-%, more preferably of from 30 to 70 weight-%, more preferably of from 40 to 60 weight-%, more preferably of from 45 to 55 weight-%, based on the total weight of the oxygen storage compound of the coating of the third catalyst.

[0130] 59. The exhaust gas treatment system of any one of embodiments 51 to 58, wherein the support material of the first catalytic coating of the third catalyst comprises one or more rare earth metals, and wherein the one or more rare earth metals are selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, and mixtures of two or more thereof, preferably from the group consisting of La, Ce, and mixtures thereof, more preferably wherein the one or more rare earth metals is La.

[0131] 60. The exhaust gas treatment system of embodiment 59, wherein the content of the one or more rare earth metals of the support material of the first catalytic coating is in the range of from 0.1 to 80 weight-%, preferably of from 0.5 to 70 weight-%, more preferably of from 1 to 60 weight-%, more preferably of from 3 to 50 weight-%, more preferably of from 5 to 40 weight-%, more preferably of from 10 to 30 weight-%, more preferably of from 15 to 25 weight-%, based on the total weight of the support material of the first catalytic coating of the third catalyst.

[0132] 61 . The exhaust gas treatment system of embodiment 59, wherein the one or more rare earth metals is lanthanum, and wherein the lanthanum content of the support material of the first catalytic coating is in an amount in the range of from 0.1 to 30 weight-%, preferably of from 0.5 to 20 weight-%, more preferably of from 1 to 15 weight-%, more preferably of from 1.5 to 10 weight-%, more preferably of from 2 to 8 weight-%, more preferably of from 2.5 to 6 weight-%, more preferably of from 3 to 5 weight-%, more preferably of from 3.5 to 4.5 weight-%, based on the total weight of the support material of the first catalytic coating of the third catalyst.

[0133] 62. The exhaust gas treatment system of embodiment 59, wherein the one or more rare earth metals is cerium, and wherein the cerium content of the support material of the first catalytic coating is in an amount in the range of from 1 to 80 weight-%, preferably of from 5 to 70 weight-%, more preferably of from 10 to 60 weight-%, more preferably of from 20 to 50 weight-%, more preferably of from 30 to 40 weight-%, based on the total weight of the support material of the first catalytic coating of the third catalyst. The exhaust gas treatment system of any one of embodiments 51 to 62, wherein the first catalytic coating is substantially free of zeolitic material, preferably wherein the first catalytic coating comprises 0.1 g / ft3or less of zeolitic material, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the first catalytic coating is free of zeolitic material. The exhaust gas treatment system of any one of embodiments 51 to 63, wherein the first catalytic coating is free of zeolitic material and wherein the zeolitic material comprised in the AMOx coating is comprised entirely in the second catalytic coating. The exhaust gas treatment system of any one of embodiments 51 to 64, wherein first catalytic coating is substantially free of alkaline earth metal oxides and alkaline metal oxides, wherein preferably the ammonia oxidation coating comprises 0.1 g / ft3or less of alkaline earth metal oxides and alkaline metal oxides, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the ammonia oxidation coating of the third catalyst is free of alkaline earth metal oxides and alkaline metal oxides. The exhaust gas treatment system of any one of embodiments 51 to 65, wherein the first catalytic coating is substantially free of barium, wherein preferably the ammonia oxidation coating comprises 0.1 g / ft3or less of barium, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the first catalytic coating is free of barium. The exhaust gas treatment system of any one of embodiments 51 to 66, wherein the zeolitic material comprised in the second catalytic coating is selected from the group consisting of AFR, ATS, BEA, DFO, EMT, EON, FAU, GME, IWS, IWV, MEI, MSE, MOR, OFF, POS, SAO, SBE, SBS, SBT, SOR, SOV, and mixtures of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of AFR, BEA, DFO, EON, GME, IWS, IWV, MOR, OFF, SBE, SBS, SBT, and mixtures of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of BEA, MOR, OFF, and mixtures of two or more thereof and a mixed type of two or more thereof, wherein more preferably the 12-membered ring pore zeolitic material comprised in the second catalytic coating of the third catalyst has a framework type BEA. The exhaust gas treatment system of embodiments 51 to 67, wherein from 95 to 100 weight-%, preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, of the framework structure of the 12-membered ring pore zeolitic material comprised in the second catalytic coating consists of Si, Al, and O, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO2:AhO3, is more preferably in the range of from 1 to 100, more preferably in the range of from 3 to 50, more preferably in the range of from 5 to 20, more preferably in the range of from 7 to 15, more preferably in the range of from 7.5 to 12.5 . 69. The exhaust gas treatment system of any one of embodiments 51 to 68, wherein the zeolitic material comprised in the second catalytic coating comprises iron, wherein the amount of iron comprised in the zeolitic material, calculated as Fe2Os, is preferably in the range of from 0.1 to 10.0 weight-%, more preferably in the range of from 0.5 to 8 weight-%, more preferably in the range of from 1 .5 to 7.5 weight-%, based on the total weight of the zeolitic material.

[0134] 70. The exhaust gas treatment system of any one of embodiments 51 to 69, wherein the second catalytic coating is substantially free of Cu, preferably wherein the second catalytic coating comprises 0.1 weight-% or less of Cu, more preferably 0.01 weight-% or less, more preferably 0.001 weight-% or less, more preferably wherein the second catalytic coating of the third catalyst is free of Cu.

[0135] 71 . The exhaust gas treatment system of any one of embodiments 51 to 70, wherein the second catalytic coating further comprises a non-zeolitic oxidic material, wherein the non-zeolitic ox- idic material is selected from the group consisting of zirconia, alumina, ceria, titania, silica, and mixtures of two or more thereof, preferably from the group consisting of zirconia, alumina, ceria, silica, and mixtures of two or more thereof, more preferably from the group consisting of zirconia, alumina, or mixtures thereof, more preferably wherein the non-zeolitic oxidic material is zirconia and alumina.

[0136] 72. The exhaust gas treatment system of embodiment 71 , wherein the second catalytic coating comprises the non-zeolitic oxidic material in an amount, calculated as the oxide, in the range of from 0.5 to 12 weight-%, preferably in the range of from 1 to 10 weight-%, more preferably in the range of from 1 to 6 weight-%, based on the washcoat loading of the second catalytic coating.

[0137] 73. The exhaust gas treatment system of any one of embodiments 51 to 72, wherein the second catalytic coating is substantially free of ceria, preferably wherein the second catalytic coating comprises 0.1 weight-% or less of ceria, more preferably 0.01 weight-% or less, more preferably 0.001 weight-% or less, more preferably wherein the second catalytic coating is free of ceria.

[0138] 74. The exhaust gas treatment system of any one of embodiments 51 to 73, wherein the second catalytic coating is substantially free of platinum group metals, preferably wherein the second catalytic coating comprises 0.1 weight-% or less of platinum group metals, more preferably 0.01 weight-% or less, more preferably 0.001 weight-% or less, more preferably wherein the second catalytic coating is free of platinum group metals.

[0139] 75. The exhaust gas treatment system of any one of embodiments 51 to 74, wherein the second catalytic coating is free of platinum group metals and wherein the one or more platinum group metals comprised in the AMOx coating are comprised entirely in the first catalytic coating. 76. The exhaust gas treatment system of any one of embodiments 51 to 75, wherein the loading of the second catalytic coating is in the range of from 0.1 to 20 g / in3, preferably in the range of from 1 to 15 g / in3, more preferably in the range of from 2 to 10 g / in3, more preferably in the range of from 2.5 to 8 g / in3, more preferably in the range of from 3 to 6 g / in3, more preferably in the range of from 3.05 to 5.5 g / in3, more preferably in the range of from 3.1 to 5 g / in3, more preferably in the range of from 3.15 to 4.5 g / in3, more preferably in the range of from 3.2 to 4 g / in3, more preferably in the range of from 3.25 to 3.75 g / in3, more preferably in the range of from 3.3 to 3.5 g / in3.

[0140] 77. The exhaust gas treatment system of any one of embodiments 51 to 70, wherein from 98 to 100 weight-%, preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight- %, more preferably from 99.9 to 100 weight-%, of the second catalytic coating consists of a zeolitic material comprising one or more of Fe and Cu, and preferably a non-zeolitic oxidic material as defined in embodiment 71 or 72.

[0141] 78. The exhaust gas treatment system of any one of embodiments 51 to 77, wherein the first catalytic coating is disposed on the substrate of the third catalyst over 98 to 100 %, preferably 99 to 100%, more preferably 99.5 to 100%, of the substrate axial length, and the second catalytic coating is disposed on the first catalytic coating over 98 to 100 %, preferably 99 to 100%, more preferably 99.5 to 100%, of the substrate axial length.

[0142] 79. The exhaust gas treatment system of any one of embodiments 51 to 77, wherein the third catalyst comprises an inlet zone comprising, preferably consisting of, the first catalytic coating and an outlet zone comprising, preferably consisting of, a second catalytic coating.

[0143] 80. The exhaust gas treatment system of embodiment 79, wherein the inlet zone extends over x % of the substrate axial length from the inlet end towards the outlet end of the substrate, with x is in the range of from 20 to 60, preferably in the range of from 30 to 55, more preferably in the range of from 45 to 55.

[0144] 81 . The exhaust gas treatment system of embodiment 79 or 80, wherein the outlet zone extends over y % of the substrate axial length, with y = 100 - x, from the outlet end towards the inlet end of the substrate.

[0145] 82. The exhaust gas treatment system of any one of embodiments 79 to 81 , wherein the second catalytic coating is disposed on the substrate of the third catalyst over 50% of the substrate axial length, forming the inlet zone.

[0146] 83. The exhaust gas treatment system of any one of embodiments 79 to 82, wherein the first catalytic coating is disposed on the substrate of the third catalyst over 50% of the substrate axial length. 84. The exhaust gas treatment system of any one of embodiments 51 to 83, wherein from 98 to 100 weight-%, preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight- %, more preferably from 99.9 to 100 weight-%, of the first catalytic coating of the third catalyst consists of one or more platinum group metals, a support material supporting the platinum group metal and one or more rare earth metals comprised in the support material.

[0147] 85. The exhaust gas treatment system of any one of embodiments 1 to 84, wherein the third catalyst consists of the substrate and the AMOx coating.

[0148] 86. A method for the simultaneous selective catalytic reduction of NOx, the oxidation of a hydrocarbon, the oxidation of nitrogen monoxide, and the oxidation of ammonia, comprising

[0149] (1 ) providing an exhaust gas stream from a gasoline engine comprising one or more of NOx, ammonia, nitrogen monoxide and a hydrocarbon;

[0150] (2) passing the exhaust gas stream provided in (1 ) through the exhaust gas system according to any one of embodiments 1 to 85.

[0151] The present invention is further illustrated by the following reference examples, examples and comparative examples.

[0152] EXAMPLES

[0153] Reference Example 1 : Determination of the volume-based particle size distributions Dv90

[0154] The particle size distributions were determined by a static light scattering method using a Sym- patec HELOS / BR-OM & QUIXEL wet dispersion equipment, fitted with laser (HeNe) diffraction sensor with 31 channel multi element detection range comprising 5 modules covering 0.1- 875 microns.

[0155] Reference Example 2: A three-way conversion (TWC) catalyst

[0156] An aqueous mixture of palladium and rhodium salt precursors were impregnated on high porosity alumina and ceria-zirconia. The obtained mixture of Pd / Rh on alumina and ceria-zirconia (solid content: 60-75 wt.-%) was calcined at 400-600 °C for 2-4 hours.

[0157] A mixture was prepared by mixing water, n-octanol and a precursor of baria and zirconia. The amount of the baria precursor was calculated such that the final loading of BaO in the catalyst after calcination was 1-10 wt.-% based on the weight of the coating and the amount of zirconia precursor was calculated such that the loading of ZrC>2, from said source, in the catalyst after calcination was 1-5 wt.-% based on the weight of the coating. The obtained calcined Pd / Rh on alumina and / or ceria-zirconia was added to the mixture comprising n-octanol obtaining a slurry. The slurry solid content was adjusted to 30-50 wt.-% to enhance pH and viscosity measurements and wet milling. After milling, the pH of the slurry was adjusted by adding nitric acid to have a pH of 3-5. The particle size distribution (Dv90) of the slurry was after milling was of 10-20 micrometers.

[0158] The obtained slurry was disposed over the entire length of a non-coated ceramic honeycomb flow through substrate (diameter: 4.66 inches x length: 4.5 inches, cylindrical shaped substrate with 750 / (2.5)2cells per square centimeter and 0.0635 millimeter (2.5 mil) wall thickness), dried at 120- 180°C and further calcined at 400-600 °C in air. The final coating comprises high porosity alumina, ceria-zirconia, Pd, Rh, zirconia and baria. The loading of the coating is from 1 .5 to 4 g / in3.

[0159] Reference Example 3: A four-way conversion (FWC) catalyst

[0160] An aqueous mixture of palladium and rhodium salt precursors were impregnated on high porosity alumina and ceria-zirconia. The obtained mixture of Pd / Rh on alumina and ceria-zirconia (solid content: 50-80 wt.-%) was calcined at 400-600 °C for 2-4 hours.

[0161] A mixture was prepared by mixing water, n-octanol and a precursor of baria and zirconia. The amount of the baria precursor was calculated such that the final loading of BaO in the catalyst after calcination was 1-5 wt.-% based on the weight of the coating and the amount of zirconia precursor was calculated such that the loading of ZrC>2, from said source, in the catalyst after calcination was 1-5 wt.-% based on the weight of the coating. The obtained calcined Pd / Rh on alumina and / or ceria-zirconia was added to the mixture comprising n-octanol obtaining a slurry. The slurry solid content was adjusted to 30-50 wt.-% to enhance pH and viscosity measurements and wet milling. After milling, the pH of the slurry was adjusted by adding nitric acid to have a pH of 3-5. The particle size distribution (Dv90) of the slurry was after milling was of 7-18 micrometers.

[0162] The obtained slurry was disposed over the entire length of a non-coated ceramic honeycomb wall flow substrate (diameter: 4.66 inches x length: 4.26 inches, cylindrical shaped substrate with 300 / (2.54)2cells per square centimeter and 0.2 millimeter (8 mil) wall thickness), dried at 120-180 °C and further calcined at 400-600 °C in air. The final coating comprises high porosity alumina, ceria-zirconia, Pd, Rh, zirconia and baria. The loading of the coating is from 1 to 3 g / in3.

[0163] Reference Example 4: A three-way conversion (TWC) catalyst

[0164] An aqueous mixture of palladium and rhodium salt precursors were impregnated on high porosity alumina and ceria-zirconia. The obtained mixture of Pd / Rh on alumina and ceria-zirconia (solid content: 60-75 wt.-%) was calcined at 400-600 °C for 2-4 hours.

[0165] A mixture was prepared by mixing water, n-octanol and a precursor of baria and zirconia. The amount of the baria precursor was calculated such that the final loading of BaO in the catalyst after calcination was 5-10 wt.-% based on the weight of the coating and the amount of zirconia precursor was calculated such that the loading of ZrO2, from said source, in the catalyst after calcination was 1-5 wt.-% based on the weight of the coating. The obtained calcined Pd / Rh on alumina and / or ceria-zirconia was added to the mixture comprising n-octanol obtaining a slurry. The slurry solid content was adjusted to 35-45 wt.-% to enhance pH and viscosity measurements and wet milling. After milling, the pH of the slurry was adjusted by adding nitric acid to have a pH of 3-5. The particle size distribution (Dv90) of the slurry was after milling was of 15-22 micrometers.

[0166] The obtained slurry was disposed over the entire length of a non-coated ceramic honeycomb flow through substrate (diameter: 5.66 inches x length: 3.0 inches, cylindrical shaped substrate with 750 / (2.5)2cells per square centimeter and 0.0635 millimeter (2.5 mil) wall thickness), dried at 120- 180°C and further calcined at 400-600 °C in air. The final coating comprises high porosity alumina, ceria-zirconia, Pd, Rh, zirconia and baria. The loading of the coating is from 1 .5 to 3 g / in3.

[0167] Comparative Example 1 : An exhaust gas treatment system not according to the present invention

[0168] The exhaust gas treatment system of Comparative Example 1 comprises the catalyst of Reference Example 1 (TWC catalyst) as Catalyst 1 , the catalyst of Reference Example 2 (FWC catalyst) as Catalyst 2 and the catalyst of Reference Example 4 (TWC catalyst) as Catalyst 3, wherein Catalyst 1 is located upstream of Catalyst 2 and Catalyst 2 is located upstream of Catalyst 3. No catalysts are present between Catalyst 1 and 2, and Catalyst 2 and 3, and Catalyst 1 is a close coupled catalyst. The system is illustrated in Figure 1 .

[0169] Reference Example 5: An ammonia oxidation (AMOx) catalyst

[0170] PGM-containing bottom coating:

[0171] An aqueous mixture of a Pt precursor was impregnated on high surface area and porous oxidic lanthanum-doped alumina (4 wt.-% La content of the doped alumina) in an aqueous medium. The obtained mixture had a solid content of 50-70%. Said slurry was wet milled such as to obtain a Dv90 of 5-15 micrometers. The obtained slurry was then disposed over the entire length of a noncoated ceramic honeycomb flow through substrate (diameter: 5.66 inches x length: 3 inches, cylindrical shaped substrate with 400 / (2.54)2cells per square centimeter and 0.1 millimeter (4 mil) wall thickness), dried at 120-180 °C and calcined at 400-600 °C in air. The loading of the PGM coating was 2.5-4.5 g / in3.

[0172] PGM-free top coating:

[0173] A mixture of distilled water and a Fe-BEA zeolite (Fe content, calculated as Fe2Os: 1.5 to 7.5 weight-% based on the weight of the zeolite, a silica to alumina molar ratio of 6-15:1 ) was prepared. Zirconia and alumina (1-5 wt.-%) were added to said mixture under constant mixing. The solid content of the obtained slurry was 30-50%. The slurry was dispersed and mixed such as to obtain a Dv90 of 5-15 micrometers. The obtained slurry was then disposed over the entire length of the substrate coated with the PGM-containing bottom coating, dried at 120-180 °C and calcined at 400-600 °C in air. The loading of the PGM-free coating was 2.5-3.5 g / in3.

[0174] Comparative Example 2: An exhaust gas treatment system not according to the present invention The exhaust gas treatment system of Comparative Example 1 comprises the catalyst of Reference Example 1 (TWC catalyst) as Catalyst 1 , the catalyst of Reference Example 2 (FWC catalyst) as Catalyst 2 and the catalyst of Reference Example 5 (AMOx catalyst) as Catalyst 3, wherein Catalyst 1 is located upstream of Catalyst 2 and Catalyst 2 is located upstream of Catalyst 3. No catalysts are present between Catalyst 1 and 2, and Catalyst 2 and 3, and Catalyst 1 is a close coupled catalyst. The system is illustrated in Figure 1.

[0175] Reference Example 6: An ammonia oxidation (TWC / AMOx) catalyst

[0176] PGM-containing bottom coating:

[0177] An aqueous mixture of a Pt precursor was impregnated on high surface area and porous oxidic ceria-alumina (30 wt.-% CeO2 content) in an aqueous medium. The obtained mixture had a solid content of 50-70%. Said slurry was wet milled such as to obtain a Dv90 of 5-15 micrometers. The obtained slurry was then disposed over the entire length of a non-coated ceramic honeycomb flow through substrate (diameter: 5.66 inches x length: 3 inches, cylindrical shaped substrate with 400 / (2.54)2cells per square centimeter and 0.1 millimeter (4 mil) wall thickness), dried at 120-180 °C and calcined at 400-600 °C in air. The loading of the PGM coating was 2.5-4.5 g / in3.

[0178] PGM-free top coating:

[0179] A mixture of distilled water and a Fe-BEA zeolite (Fe content, calculated as Fe2Os: 1.5 to 7.5 weight-% based on the weight of the zeolite, a silica to alumina molar ratio of 6-15:1 ) was prepared. Zirconia and alumina (1-5 wt.-%) were added to said mixture under constant mixing. The solid content of the obtained slurry was 30-50%. The slurry was dispersed and mixed such as to obtain a Dv90 of 5-15 micrometers. The obtained slurry was then disposed over the entire length of the substrate coated with the PGM-containing bottom coating, dried at 120-180 °C and calcined at 400-600 °C in air. The loading of the PGM-free coating was 2.5-3.5 g / in3.

[0180] Example 1 : An exhaust gas treatment system according to the present invention

[0181] The exhaust gas treatment system of Comparative Example 1 comprises the catalyst of Reference Example 1 (TWC catalyst) as Catalyst 1 , the catalyst of Reference Example 2 (FWC catalyst) as Catalyst 2 and the catalyst of Reference Example 6 ((TWC / AMOx) catalyst) as Catalyst 3, wherein Catalyst 1 is located upstream of Catalyst 2 and Catalyst 2 is located upstream of Catalyst 3. No catalysts are present between Catalyst 1 and 2, and Catalyst 2 and 3, and Catalyst 1 is a close coupled catalyst. The system is illustrated in Figure 1 .

[0182] Reference Example 7: An ammonia oxidation (TWC / AMOx) catalyst

[0183] PGM-containing bottom coating:

[0184] An aqueous mixture of a Pt precursor was impregnated on high surface area and porous oxidic ceria- alumina (70 wt.-% CeO2) in an aqueous medium. The obtained mixture had a solid content of 50-70%. Said slurry was wet milled such as to obtain a Dv90 of 5-15 micrometers. The obtained slurry was then disposed over the entire length of a non-coated ceramic honeycomb flow through substrate (diameter: 5.66 inches x length: 3 inches, cylindrical shaped substrate with 400 / (2.54)2cells per square centimeter and 0.1 millimeter (4 mil) wall thickness), dried at 120-180 °C and calcined at 400-600 °C in air. The loading of the PGM coating was 2.5-4.5 g / in3.

[0185] PGM-free top coating:

[0186] A mixture of distilled water and a Fe-BEA zeolite (Fe content, calculated as Fe2Os: 1.5 to 7.5 weight-% based on the weight of the zeolite, a silica to alumina molar ratio of 6-15:1 ) was prepared. Zirconia and alumina (1-5 wt.-%) were added to said mixture under constant mixing. The solid content of the obtained slurry was 30-50%. The slurry was dispersed and mixed such as to obtain a Dv90 of 5-15 micrometers. The obtained slurry was then disposed over the entire length of the substrate coated with the PGM-containing bottom coating, dried at 120-180 °C and calcined at 400-600 °C in air. The loading of the PGM-free coating was 2.5-3.5 g / in3.

[0187] Example 2: An exhaust gas treatment system according to the present invention

[0188] The exhaust gas treatment system of Comparative Example 1 comprises the catalyst of Reference Example 1 (TWC catalyst) as Catalyst 1 , the catalyst of Reference Example 2 (FWC catalyst) as Catalyst 2 and the catalyst of Reference Example 7 ((TWC / AMOx) catalyst) as Catalyst 3, wherein Catalyst 1 is located upstream of Catalyst 2 and Catalyst 2 is located upstream of Catalyst 3. No catalysts are present between Catalyst 1 and 2, and Catalyst 2 and 3, and Catalyst 1 is a close coupled catalyst. The system is illustrated in Figure 1.

[0189] Reference Example 8: An ammonia oxidation (TWC / AMOx) catalyst

[0190] PGM-containing bottom coating:

[0191] An aqueous mixture of a Rh precursor was impregnated on high surface area and porous oxidic lanthanum-doped alumina (4 wt.-% La content of the doped alumina) in an aqueous medium. The obtained mixture had a solid content of 50-70%. Said slurry was wet milled such as to obtain a Dv90 of 5-15 micrometers. The obtained slurry was then disposed over the entire length of a noncoated ceramic honeycomb flow through substrate (diameter: 5.66 inches x length: 3 inches, cylindrical shaped substrate with 400 / (2.54)2cells per square centimeter and 0.1 millimeter (4 mil) wall thickness), dried at 120-180 °C and calcined at 400-600 °C in air. The loading of the PGM coating was 2.5-4.5 g / in3.

[0192] PGM-free top coating:

[0193] A mixture of distilled water and a Fe-BEA zeolite (Fe content, calculated as Fe2Os: 1.5 to 7.5 weight-% based on the weight of the zeolite, a silica to alumina molar ratio of 6-15:1 ) was prepared. Zirconia and alumina (1-5 wt.-%) were added to said mixture under constant mixing. The solid content of the obtained slurry was 30-50%. The slurry was dispersed and mixed such as to obtain a Dv90 of 5-15 micrometers. The obtained slurry was then disposed over the entire length of the substrate coated with the PGM-containing bottom coating, dried at 120-180 °C and calcined at 400-600 °C in air. The loading of the PGM-free coating was 2.5-3.5 g / in3. Example 3: An exhaust gas treatment system according to the present invention

[0194] The exhaust gas treatment system of Comparative Example 1 comprises the catalyst of Reference Example 1 (TWC catalyst) as Catalyst 1 , the catalyst of Reference Example 2 (FWC catalyst) as Catalyst 2 and the catalyst of Reference Example 8 ((TWC / AMOx) catalyst) as Catalyst 3, wherein Catalyst 1 is located upstream of Catalyst 2 and Catalyst 2 is located upstream of Catalyst 3. No catalysts are present between Catalyst 1 and 2, and Catalyst 2 and 3, and Catalyst 1 is a close coupled catalyst. The system is illustrated in Figure 1 .

[0195] Reference Example 9: An ammonia oxidation (TWC / AMOx) catalyst

[0196] PGM-containing bottom coating:

[0197] An aqueous mixture of a Rh precursor was impregnated on high surface area and porous oxidic ceria-alumina (30 wt.-% CeO2 content) in an aqueous medium. The obtained mixture had a solid content of 50-70%. Said slurry was wet milled such as to obtain a Dv90 of 5-15 micrometers. The obtained slurry was then disposed over the entire length of a non-coated ceramic honeycomb flow through substrate (diameter: 5.66 inches x length: 3 inches, cylindrical shaped substrate with 400 / (2.54)2cells per square centimeter and 0.1 millimeter (4 mil) wall thickness), dried at 120-180 °C and calcined at 400-600 °C in air. The loading of the PGM coating was 2.5-4.5 g / in3.

[0198] PGM-free top coating:

[0199] A mixture of distilled water and a Fe-BEA zeolite (Fe content, calculated as Fe2Os: 1.5 to 7.5 weight-% based on the weight of the zeolite, a silica to alumina molar ratio of 6-15:1 ) was prepared. Zirconia and alumina (1-5 wt.-%) were added to said mixture under constant mixing. The solid content of the obtained slurry was 30-50%. The slurry was dispersed and mixed such as to obtain a Dv90 of 5-15 micrometers. The obtained slurry was then disposed over the entire length of the substrate coated with the PGM-containing bottom coating, dried at 120-180 °C and calcined at 400-600 °C in air. The loading of the PGM-free coating was 2.5-3.5 g / in3.

[0200] Example 4: An exhaust gas treatment system according to the present invention

[0201] The exhaust gas treatment system of Comparative Example 1 comprises the catalyst of Reference Example 1 (TWC catalyst) as Catalyst 1 , the catalyst of Reference Example 2 (FWC catalyst) as Catalyst 2 and the catalyst of Reference Example 9 ((TWC / AMOx) catalyst) as Catalyst 3, wherein Catalyst 1 is located upstream of Catalyst 2 and Catalyst 2 is located upstream of Catalyst 3. No catalysts are present between Catalyst 1 and 2, and Catalyst 2 and 3, and Catalyst 1 is a close coupled catalyst. The system is illustrated in Figure 1 .

[0202] Example 5: Testing of the systems according to Examples 1-5 and Comparative Example 1

[0203] In the different systems, Catalyst 1 (TWC) and Catalyst 2 (FWC) are located in the same can in combination with a different downstream component in Comparative Example 1 and Examples 1-4. The comparative system comprising the TWC and FWC with a TWC downstream represents a standard Euro 6 configuration, while the inventive systems composed of either an AMOx or TWC-AMOx in the underfloor position downstream of the TWC+FWC is representative of a Euro 7 gasoline application.

[0204] The systems evaluated were aged on an engine bench using a 2L Euro 6 engine, such that the canning containing a TWC+FWC was placed in the CC position, while the component (TWC, AMOx, or TWC / AMOx) under evaluation was placed downstream in a separate can. For all systems studied, five duplicates of the same CC unit was used upstream. The aging is lambda-1 type with periodic fuel-cut or lean / rich perturbations with downstream catalyst inlet temperatures of 850 °C. Aging duration was 50h. Thermocouples placed in different positions along the exhaust line could record engine out, catalyst inlet and bed and outlet temperatures.

[0205] The system and consequently component evaluation (WLTC) was carried out on a Euro 6 2I GTDI engine bench test cell. The latter is fitted with thermos-elements and FT-IR units at the engine out / catalyst inlet, catalyst bed and outlet positions, allowing for accurate recording of temperatures and gaseous emissions along the exhaust line.

[0206] Figures 2-6 present the cumulated NH3, CO and HC emissions for each tested system using the WLTC cycle collected on the vehicle described above.

[0207] As may be taken from Figure 2, the cumulated NH3 emissions are significantly higher for the comparative system compared to the inventive systems of Examples 1 , 3, and 4. The best results were obtained with the system of Example 1 , which contains Pt on Ce-doped alumina.

[0208] As may be taken from Figure 3, the cumulated CO emissions are comparable for the comparative system and the inventive systems up to 600 seconds in the WLTC cycle. At higher speed and temperature the CO emissions of the comparative system are higher than the CO emissions of the inventive systems. The best results were obtained with the system of Example 1 , which contains Pt on Ce-doped alumina.

[0209] Further, as may be taken from Figure 4, the cumulated HC emissions obtained with the comparative system are significantly higher compared to those of the inventive systems particularly at low speed and temperatures up to 220 seconds in the WLTC cycle. The best results were obtained with the system of Example 3, which contains Rh on La-doped alumina.

[0210] The cumulated NH3 emissions of comparative Example 1 and 2, and Examples 1 and 2 are displayed in Figure 5. With increasing ceria content of the support material, the cumulated NH3 emissions of the inventive Examples 1 and 2 decrease.

[0211] Finally, as may be taken from Figure 6, the cumulated CO emissions obtained decrease with increasing ceria content of the support material of the inventive Examples 1 and 2. Description of the figures

[0212] Figure 1 shows a schematic of exhaust gas treatment systems according to Examples 1-4, and comparative Examples 1 and 2.

[0213] Figure 2 shows the cumulated NH3 obtained with the systems of Examples 1 , 3, and 4, and comparative Examples 1 and 2 after aging.

[0214] Figure 3 shows the cumulated CO obtained with the systems of Examples 1 , 3, and 4, and comparative Examples 1 and 2 after aging.

[0215] Figure 4 shows the cumulated HC obtained with the systems of Examples 1 , 3, and 4, and comparative Examples 1 and 2 after aging.

[0216] Figure 5 shows the cumulated NH3 obtained with the systems of Examples 1 and 2, and comparative Examples 1 and 2 after aging.

[0217] Figure 6 shows the cumulated CO obtained with the systems of Examples 1 and 2, and comparative Examples 1 and 2 after aging.

[0218] Cited literature

[0219] - EP 3974059 A1

[0220] - EP 3310461 A1

Claims

Claims1 . An exhaust gas treatment system for treating an exhaust gas stream exiting a gasoline engine, wherein said exhaust gas treatment system has an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, and wherein said exhaust gas treatment system comprises(i) a first catalyst, being a three-way conversion catalyst, having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material;(ii) a second catalyst, being a four-way conversion catalyst, having an inlet end and an outlet end and comprising a coating disposed on a wall flow filter substrate, wherein the coating comprises one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material; or a gasoline particle filter having an inlet end and an outlet end;(iii) a third catalyst having an inlet end and an outlet end, wherein the third catalyst comprises a substrate and a coating for the oxidation of ammonia (AMOx), as well as for the reduction of nitrogen oxide, the oxidation of carbon monoxide and the oxidation of hydrocarbons (TWC), wherein the coating of the third catalyst comprises one or more platinum group metals selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material, wherein the coating of the third catalyst comprises one or more zeolitic materials, and wherein the coating of the third catalyst comprises rhodium and / or an oxygen storage compound; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst; wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst; wherein in the exhaust gas treatment system, the third catalyst according to (iii) is located downstream of the second catalyst according to (ii) and wherein the inlet end of the third catalyst is arranged upstream of the outlet end of the third catalyst.

2. The exhaust gas treatment system of claim 1 , wherein the coating of the first catalyst further comprises an oxygen storage compound (OSC).

3. The exhaust gas treatment system of claim 1 or 2, wherein the coating of the first catalyst further comprises an NOx storage component.

4. The exhaust gas treatment system of any one of claims 1 to 3, wherein the coating of the second catalyst further comprises an oxygen storage compound (OSC).

5. The exhaust gas treatment system of any of claims 1 to 4, wherein the coating of the second catalyst further comprises a non-zeolitic oxidic material.

6. The exhaust gas treatment system of any of claims 1 to 5, wherein the coating of the second catalyst further comprises an oxide of an alkaline earth metal.

7. The exhaust gas treatment system of any one of claims 1 to 6, wherein the third catalyst is substantially free of palladium.

8. The exhaust gas treatment system of any one of claims 1 to 7, wherein the coating of the third catalyst comprises an oxygen storage compound (OSC).

9. The exhaust gas treatment system of claim 8, wherein the cerium content of the oxygen storage compound in the coating of the third catalyst is in the range of from 5 to 81 .46 weight-%, based on the total weight of the oxygen storage compound of the coating of the third catalyst.

10. The exhaust gas treatment system of any one of claims 1 to 9, wherein the support material of the coating of the third catalyst comprises one or more rare earth metals, and wherein the one or more rare earth metals are selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, and mixtures of two or more thereof.11 . The exhaust gas treatment system of any one of claims 1 to 10, wherein the one or more zeolitic materials comprised in the coating of the third catalyst comprise one or more of Fe and Cu.

12. The exhaust gas treatment system of any one of claims 1 to 11 , wherein the coating of the third catalyst comprises a first catalytic coating comprising one or more platinum group metals supported on a support material, and a second catalytic coating comprising one or more zeolitic materials, wherein the first catalytic coating comprises rhodium and / or an oxygen storage compound.

13. The exhaust gas treatment system of claim 12, wherein the first catalytic coating is disposed on the substrate of the third catalyst over 98 to 100 % of the substrate axial length.

14. The exhaust gas treatment system of claim 12, wherein the third catalyst comprises an inlet zone comprising the first catalytic coating and an outlet zone comprising a second catalytic coating.

15. A method for the simultaneous selective catalytic reduction of NOx, the oxidation of a hydrocarbon, the oxidation of nitrogen monoxide, and the oxidation of ammonia, comprising(1 ) providing an exhaust gas stream from a gasoline engine comprising one or more of NOx, ammonia, nitrogen monoxide and a hydrocarbon; (2) passing the exhaust gas stream provided in (1 ) through the exhaust gas system according to any one of claims 1 to 14.

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