Amox catalyst on gasoline particle filter

Abstract

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 metal components 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, comprising, preferably consisting of, a gasoline particle filter having an inlet end and an outlet end, and comprising a coating for the oxidation of ammonia (AMOx) disposed on a filter substrate, wherein the coating of the second catalyst comprises one or more platinum group metal components selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material, and wherein the coating of the second catalyst comprises one or more zeolitic materials; wherein the first catalyst according to (i) is located 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.

Description

[0001] AMOx Catalyst on Gasoline Particle Filter

[0002] TECHNICAL FIELD

[0003] The present invention relates 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] Emissions 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] DETAILED DESCRIPTION

[0008] 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), carbon monoxide (CO) and / or nitrogen oxides (NOx) tailpipe emissions compared to systems according to the prior art such as, e.g., EURO 6 or other systems. In addition to improved ammonia slippage control, it was found that the system of the present invention contributes significantly to HC, CO and NOx emissions reduction.

[0009] 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

[0010] (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 metal components selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material;

[0011] (ii) a second catalyst, comprising, preferably consisting of, a gasoline particle filter having an inlet end and an outlet end, and comprising a coating for the oxidation of ammonia (AMOx) disposed on a filter substrate, wherein the coating of the second catalyst comprises one or more platinum group metal components selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material, and wherein the coating of the second catalyst comprises one or more zeolitic materials; wherein the first catalyst according to (i) is located 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.

[0012] 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.

[0013] It is preferred that the one or more platinum group metal components of the coating of the first catalyst are platinum, palladium and rhodium.

[0014] It is preferred that the coating of the first catalyst comprises the one or more platinum group metal components at a loading, calculated as elemental platinum group metal, in the range of from 1 to 20 g / ft3, more preferably in the range of from 2 to 10 g / ft3, more preferably in the range of from 3 to 5 g / ft3, more preferably in the range of from 3.5 to 4.5 g / ft3, more preferably in the range of from 3.8 to 4.2 g / ft3.

[0015] It is preferred that the weight ratio of Pt to Pd in the coating of the first catalyst is in the range of from 0.01 :1 to 1 :0.01 , more preferably in the range of from 0.1 :1 to 1 :0.1 , more preferably in the range of from 0.5:1 to 1 :0.5, more preferably in the range of from 0.7:1 to 1 :0.7, more preferably in the range of from 0.9:1 to 1 :0.9.

[0016] It is preferred that the weight ratio of Rh to Pt in the coating of the first catalyst is in the range of from 0.01 :1 to 0.5:1 , more preferably in the range of from 0.05:1 to 0.4:1 , more preferably in the range of from 0.1 :1 to 0.3:1 , more preferably in the range of from 0.15:1 to 0.25:1.

[0017] It is preferred that the weight ratio of Rh to Pd in the coating of the first catalyst is in the range of from 0.01 :1 to 0.5:1 , more preferably in the range of from 0.05:1 to 0.4:1 , more preferably in the range of from 0.1 :1 to 0.3:1 , more preferably in the range of from 0.15:1 to 0.25:1. 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, more preferably selected from the group consisting of alumina, ceria, 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 thereof, and a mixed oxide thereof, more preferably wherein the support material is alumina.

[0018] It is preferred that the support material supporting the platinum group metal component of the coating of the first 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, more preferably from the group consisting of La, Ce, and mixtures thereof, more preferably wherein the one or more rare earth metals is lanthanum.

[0019] It is preferred that the coating of the first catalyst further comprises an oxygen storage compound, the oxygen storage compound more preferably comprises cerium, more preferably comprises one or more of a cerium oxide, a mixture of oxides comprising cerium 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.

[0020] In case that 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 0.01 to 3 g / in3, more preferably in the range of from 0.1 to 2 g / in3, more preferably in the range of from 0.2 to 1 g / in3, more preferably in the range of from 0.3 to 0.9 g / in3, more preferably in the range of from 0.4 to 0.8 g / in3, more preferably in the range of from 0.5 to 0.7 g / in3. 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 1 :1 to 5:1 , more preferably in the range of from 2:1 to 4:1 , more preferably in the range of from 2.5:1 to 3.5:1.

[0021] It is preferred that the coating of the first catalyst further comprises a non-zeolitic oxidic material, the non-zeolitic oxidic material more preferably comprises one or more of zirconia, alumina, ceria, titania, silica, lanthana and a mixed oxide comprising two or more of Zr, Al, Ce, Ti, Si, and La, more preferably comprises one or more of zirconia, alumina, lanthana and silica, more preferably comprises one or more of zirconia and lanthana, more preferably comprises zirconia and lanthana.

[0022] It is preferred that the coating of the first catalyst comprises the non-zeolitic oxidic material, calculated as the oxide, in the range of from 0.1 to 10 weight-%, more preferably of from 0.3 to 5 weight-%, more preferably of from 0.5 to 3 weight-%, based on the weight of the coating of the first catalyst. It is preferred that the non-zeolitic oxidic material is zirconia and wherein the coating of the first catalyst comprises zirconia, calculated as the oxide, in the range of from 0.1 to 7 weight-%, more preferably of from 0.3 to 5 weight-%, more preferably of from 0.5 to 3 weight-%, based on the weight of the coating of the first catalyst.

[0023] It is preferred that the non-zeolitic oxidic material is lanthana and wherein the coating of the first catalyst comprises lanthana, calculated as the oxide, in the range of from 0.1 to 8 weight-%, more preferably of from 0.5 to 5 weight-%, more preferably of from 1 to 3 weight-%, based on the weight of the coating of the first catalyst.

[0024] It is preferred that the coating of the first catalyst further comprises an NOx storage component, more preferably wherein the NOx storage component comprises one or more of an oxide of an alkali earth metal and an oxide of an alkali 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, Cs and mixtures of two or more thereof, 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.

[0025] In case that the first catalyst further comprises an NOx storage component, 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 10 weight-%, more preferably of from 0.5 to 7 weight-%, more preferably of from 1 to 5 weight-%, based on the weight of the coating of the first catalyst.

[0026] It is preferred that from 98 to 100 weight-%, more 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 metal components supported on a support material, more preferably an oxygen storage compound, more preferably a non-zeolitic oxidic material, and more preferably an NOx storage component.

[0027] It is preferred that the coating of the first catalyst comprises a first catalytic coating comprising palladium supported on a first support material, a second catalytic coating comprising platinum supported on second a support material, and a third catalytic coating comprising rhodium supported on a third support material.

[0028] In case that the first catalyst comprises a first catalytic coating comprising palladium supported on a first support material, a second catalytic coating comprising platinum supported on second a support material, and a third catalytic coating comprising rhodium supported on a third support material, it is preferred that the first support material of the palladium comprised in the first catalytic coating 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, more preferably selected from the group consisting of alumina, ceria, zirconia, a mixture of two or more thereof, and a mixed oxide of two or more thereof, more preferably wherein the first support material is ceria-zirconia. Further, it is preferred that the first catalytic coating is disposed over 20 to 70%, more preferably over 30 to 60%, more preferably over 40 to 50% from the inlet end towards the outlet end of the substrate.

[0029] Yet further, it is preferred that the second support material of the platinum comprised in the second catalytic coating 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, more preferably selected from the group consisting of alumina, silica, titania, a mixture of two or more thereof, and a mixed oxide of two or more thereof, more preferably wherein the second support material is alumina.

[0030] Yet further, it is preferred that the second support material 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, more preferably from the group consisting of La, Ce, and mixtures thereof, more preferably wherein the one or more rare earth metals is lanthanum.

[0031] Yet further, it is preferred that the second catalytic coating is disposed over 30 to 80%, more preferably over 40 to 70, more preferably over 50 to 60%, from the outlet end towards the inlet end of the substrate.

[0032] Yet further, it is preferred that the third support material of the rhodium comprised in the third catalytic coating 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, more preferably selected from the group consisting of alumina, silica, titania, a mixture of two or more thereof, and a mixed oxide of two or more thereof, more preferably wherein the third support material is alumina.

[0033] Yet further, it is preferred that the third support material further 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, more preferably from the group consisting of La, Ce, and mixtures thereof, more preferably wherein the one or more rare earth metals is lanthanum.

[0034] Yet further, it is preferred that the third catalytic coating is disposed on the first and second catalytic coating over 98 to 100%, more preferably 99 to 100%, more preferably 99.5 to 100%, of the substrate axial length.

[0035] It is preferred that the coating of the first catalyst comprises a first catalytic coating comprising palladium supported on a first support material and platinum supported on second a support material, and a second catalytic coating comprising rhodium supported on a third support material. In case that the coating of the first catalyst comprises a first catalytic coating comprising palladium supported on a first support material and platinum supported on second a support material, and a second catalytic coating comprising rhodium supported on a third support material, it is preferred that the first support material of the palladium comprised in the first catalytic coating 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, more preferably selected from the group consisting of alumina, ceria, zirconia, a mixture of two or more thereof, and a mixed oxide of two or more thereof, more preferably wherein the first support material is ceria-zirconia. Further, it is preferred that the second support material of the platinum comprised in the first catalytic coating 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, more preferably selected from the group consisting of alumina, silica, titania, a mixture of two or more thereof, and a mixed oxide of two or more thereof, more preferably wherein the second support material is alumina.

[0036] Yet further, it is preferred that the second support material 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, more preferably from the group consisting of La, Ce, and mixtures thereof, more preferably wherein the one or more rare earth metals is lanthanum.

[0037] Yet further, it is preferred that the first catalytic coating is disposed over 98 to 100%, more preferably 99 to 100%, more preferably 99.5 to 100%, of the substrate axial length.

[0038] Yet further, it is preferred that the third support material of the rhodium comprised in the second catalytic coating 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, more preferably selected from the group consisting of alumina, silica, titania, a mixture of two or more thereof, and a mixed oxide of two or more thereof, more preferably wherein the third support material is alumina.

[0039] Yet further, it is preferred that the third support material further 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, more preferably from the group consisting of La, Ce, and mixtures thereof, more preferably wherein the one or more rare earth metals is lanthanum.

[0040] Yet further, it is preferred that the second catalytic coating is disposed on the first catalytic coating over 98 to 100%, more preferably 99 to 100%, more preferably 99.5 to 100%, of the substrate axial length.

[0041] It is preferred that the substrate of the first catalyst is a flow-through substrate, more preferably a ceramic flow-through substrate, wherein the ceramic flow-through substrate more 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.

[0042] It is preferred that the first catalyst consists of the substrate and the coating.

[0043] It is preferred that the gasoline particle filter is a wall-flow filter, more preferably a honeycomb wall-flow filter.

[0044] In case that the gasoline particle filter is a wall-flow filter, it is preferred that the wall-flow filter is a ceramic wall-flow filter, wherein the ceramic wall-flow filter 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.

[0045] It is preferred that the one or more platinum group metal components of the AMOx coating of the second catalyst are selected from the group consisting of Pt, Rh, and mixtures thereof, more preferably wherein the one or more platinum group metal components of the AMOx coating of the third catalyst is Pt.

[0046] It is preferred that the platinum group metal loading of the coating of the second catalyst is in the range of from 0.1 to 100 g / ft3, more preferably in the range of from 1 to 50 g / ft3, more preferably in the range of from 1 to 30 g / ft3, more preferably in the range of from 2 to 25 g / ft3.

[0047] It is preferred that the second catalyst is substantially free of palladium, more preferably wherein the second 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 second catalyst is free of palladium.

[0048] It is preferred that the coating of the second catalyst is substantially free of palladium, more preferably wherein the catalytic coating of the second 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 second catalyst is free of palladium.

[0049] It is preferred that the loading of the coating of the second catalyst is in the range of from 0.1 to 25 g / in3, more preferably in the range of from 0.5 to 10 g / in3, more preferably in the range of from 1 to 5 g / in3, more preferably in the range of from 1 to 3 g / in3, more preferably in the range of from 1.2 to 2 g / in3.

[0050] It is preferred that the support material of the coating of the second 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, more preferably selected from the group consisting of titania, alumina and silica, more preferably is alumina. It is preferred that the support material of the coating of the second 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, more preferably from the group consisting of La, Ce, and mixtures thereof, more preferably wherein the one or more rare earth metals is lanthanum.

[0051] In case that the support material of the coating of the second 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 second catalyst is in the range of from 0.1 to 80 weight-%, more preferably of from 0.5 to 70 weight-%, more preferably of from 1 to 60 weight-%, more preferably of from 1 to 50 weight-%, more preferably of from 1 to 40 weight-%, more preferably of from 1 to 35 weight-%, based on the total weight of the support material of the coating of the second catalyst. Further, 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 second catalyst is in the range of from 0.1 to 80 weight-%, more preferably of from 5 to 70 weight-%, more preferably of from 10 to 50 weight-%, more preferably of from 20 to 40 weight-%, more preferably of from 25 to 35 weight-%, on the total weight of the support material of the coating of the second catalyst.

[0052] It is preferred that the coating of the second catalyst comprises the support material in the range of from 0.1 to 5 g / in3, more preferably in the range of from 0.5 to 2 g / in3, more preferably in the range of from 0.8 to 1 .7 g / in3, more preferably in the range of from 1 to 1 .5 g / in3.

[0053] It is preferred that the coating of the second catalyst further comprises an oxygen storage compound, more 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.

[0054] In case that the coating of the second catalyst further comprises an oxygen storage compound, it is preferred that the cerium content of the oxygen storage compound in the coating of the second catalyst is in the range of from 1 to 81 .46 weight-%, more preferably in the range of from 5 to 70 weight-%, more preferably in the range of from 10 to 60 weight-%, more preferably in the range of from 20 to 50 weight-%, more preferably in the range of from 30 to 45 weight-%, based on the total weight of the oxygen storage compound of the coating of the second catalyst.

[0055] It is preferred that the one or more zeolitic materials comprised in the coating of the second catalyst comprise one or more of Fe and Cu, more preferably wherein the one or more zeolitic materials comprise Fe. It is preferred that the zeolitic material comprised in the coating of the second catalyst comprises iron, wherein the amount of iron comprised in the zeolitic material, calculated as Fe2Os, is more 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.

[0056] It is preferred that the coating of the second catalyst is substantially free of Cu, more preferably wherein the coating of the second catalyst 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 coating of the second catalyst is free of Cu.

[0057] It is preferred that the one or more zeolitic materials comprised in the coating of the second catalyst is a 12-membered ring pore zeolitic material, wherein the 12-membered ring pore zeolitic material more preferably has a 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 second catalyst has a framework type BEA.

[0058] It is preferred that from 95 to 100 weight-%, preferably from 98 to 100 weight-%, more more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, of the framework structure of the one or more zeolitic materials comprised in the coating of the second catalyst consists of Si, Al, and O, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO2:AI2C>3, 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.

[0059] It is preferred that the coating of the second catalyst 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, more 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, and mixtures thereof, more preferably wherein the non-zeolitic oxidic material is zirconia.

[0060] In case that the coating of the second catalyst further comprises a non-zeolitic oxidic material, it is preferred that the coating of the second catalyst comprises the non-zeolitic oxidic material in an amount, calculated as the oxide, in the range of from 0.1 to 8 weight-%, more preferably of from 0.5 to 5 weight-%, more preferably of from 1 to 3 weight-%, based on the washcoat loading of the coating of the second catalyst.

[0061] It is preferred that the coating of the second catalyst is substantially free of alkali earth metal oxides and alkali metal oxides, wherein more preferably the coating comprises 0.1 g / ft3or less of alkali earth metal oxides and alkali metal oxides, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the coating of the second catalyst is free of alkali earth metal oxides and alkali metal oxides.

[0062] It is preferred that the coating of the second catalyst is substantially free of barium, wherein more preferably the coating of the second 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 second catalyst is free of barium.

[0063] It is preferred that the AMOx coating of the second catalyst is disposed on the inlet side over 98 to 100%, more preferably 99 to 100%, more preferably 99.5 to 100%, of the axial length of the gasoline particulate filter from the upstream end.

[0064] In case that the AMOx coating of the second catalyst is disposed on the inlet side over 98 to 100% of the axial length of the gasoline particulate filter from the upstream end, it is preferred that no coating is disposed on the outlet side of the gasoline particulate filter from the downstream end.

[0065] Alternatively, it is preferred that the AMOx coating of the second catalyst is disposed on the outlet side over 30 to 50%, more preferably 40 to 50%, more preferably 45 to 50%, of the axial length of the gasoline particulate filter from the downstream end.

[0066] As a second alternative, it is preferred that the second catalyst further comprises a flow-through substrate, wherein the flow-through substrate is downstream of the gasoline particulate filter.

[0067] In case that the second catalyst further comprises a flow-through substrate, it is preferred that the outlet end of the gasoline particulate filter is adjacent to the flow-through substrate and wherein between the outlet end of the gasoline particulate filter and the flow-through substrate no substrate or filter is located in the second catalyst. Further, it is preferred that the flow- through substrate of the second catalyst is a honeycomb flow-through substrate, more preferably a ceramic honeycomb flow-through substrate, wherein the ceramic honeycomb flow-through substrate preferably comprises, more preferably consists of, cordierite, cordierite-alpha-alumina, aluminum titanate, silicon carbide, silicon nitride, zircon mullite, spodumene, alumina-silica-mag- nesia, zircon silicate, sillimanite, magnesium silicate, zircon, petalite, alpha-alumina, or alumi- nasilicate. Yet further, it is preferred that the AMOx coating of the second catalyst is disposed on the flow-through substrate of the second catalyst over 98 to 100%, more preferably 99 to 100%, more preferably 99.5 to 100%, of the substrate length of the flow-through substrate.

[0068] In case that the AMOx coating of the second catalyst is disposed on the outlet side over 30 to 50% of the axial length of the gasoline particulate filter or in case that the second catalyst further comprises a flow-through substrate, it is preferred that the second catalyst further comprises a second catalytic coating. In case that the second catalyst further comprises a second catalytic coating, it is preferred that the second catalytic coating of the second catalyst comprises one or more platinum group metal components, wherein more preferably the one or more platinum group metal components are selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, more preferably from the group consisting of Pt, Rh, and mixtures thereof, more preferably wherein the one or more platinum group metal components are Pt and Rh. Further, it is preferred that the platinum group metal loading of the second catalytic coating of the second catalyst is in the range of from 0.1 to 100 g / ft3, more preferably in the range of from 1 to 50 g / ft3, more preferably in the range of from 1 to 30 g / ft3, more preferably in the range of from 2 to 25 g / ft3. Yet further, it is preferred that the one or more platinum group metal components of the second catalytic coating of the second catalyst are supported on a support material.

[0069] In case that the one or more platinum group metal components of the second catalytic coating of the second catalyst are supported on a support material, it is preferred that the support material supporting the one or more platinum group metal components of the second catalytic 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, more preferably selected from the group consisting of alumina, ceria, 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 thereof, and a mixed oxide thereof. Further, it is preferred that the support material supporting the one or more platinum group metal components of the second catalytic coating of the second 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, more preferably from the group consisting of La, Ce, and mixtures thereof.

[0070] In case that the support material supporting the one or more platinum group metal components of the second catalyst coating of the second 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 second catalytic coating of the second catalyst is in the range of from 0.1 to 80 weight-%, more preferably of from 0.5 to 70 weight-%, more preferably of from 1 to 60 weight-%, more preferably of from 1 to 50 weight-%, more preferably of from 1 to 40 weight-%, more preferably of from 1 to 35 weight-%, based on the total weight of the support material of the second catalytic coating of the second catalyst. Further, it is preferred that the one or more rare earth metals is cerium, and wherein the cerium content of the support material of the second catalytic coating of the second catalyst is in the range of from 1 to 80 weight-%, more preferably of from 10 to 70 weight-%, more preferably of from 15 to 60 weight-%, more preferably of from 20 to 50 weight- %, more preferably of from 30 to 45 weight-%, based on the total weight of the support material of the second catalytic coating of the second catalyst. Yet further, 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 second catalyst is in the range of from 0.1 to 10 weight-%, more preferably of from 1 to 9 weight-%, more preferably of from 1 to 8 weight-%, more preferably of from 2 to 7 weight-%, more preferably of from 3 to 6 weight-%, based on the total weight of the support material of the second catalytic coating of the second catalyst.

[0071] In case that the second catalytic coating of the second catalyst comprises one or more platinum group metal components, it is preferred that the one or more platinum group metal components are platinum and rhodium, and wherein rhodium and at least a part of the platinum are supported on the same support material.

[0072] In case that the one or more platinum group metal components are platinum and rhodium, it is preferred that the weight ratio of platinum and rhodium supported in the same support material is in the range of from 0.1 :1 to 5:1 , more preferably in the range of from 0.5:1 to 3:1 , more preferably in the range of from 0.8:1 to 2:1 , more preferably in the range of from 1 :1 to 1.5:1 , more preferably in the range of from 1.1 :1 to 1.4:1 , more preferably in the range of from 1.2:1 to 1.3:1.

[0073] In case that the second catalyst further comprises a second catalytic coating, it is preferred that the second catalytic coating of the second catalyst further comprises a non-zeolitic oxidic material, the non-zeolitic oxidic material more preferably comprises one or more of zirconia, alumina, ceria, titania, silica, lanthana and a mixed oxide comprising two or more of Zr, Al, Ce, Ti, Si, and La, more preferably comprises one or more of zirconia, alumina, lanthana and silica, more preferably comprises one or more of zirconia and lanthana, more preferably comprises zirconia. Further, it is preferred that the second catalytic coating of the second catalyst comprises the non-zeolitic oxidic material, calculated as the oxide, in the range of from 0.1 to 10 weight-%, more preferably of from 0.3 to 5 weight-%, more preferably of from 0.5 to 3 weight-%, based on the weight of the coating of the first catalyst.

[0074] In case that the second catalyst further comprises a second catalytic coating, it is preferred that the second catalytic coating of the second catalyst further comprises an NOx storage component, more preferably wherein the NOx storage component comprises one or more of an oxide of an alkali earth metal and an oxide of an alkali 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, Cs and mixtures of two or more thereof, 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. Further, it is preferred that the second catalytic coating of the second catalyst comprises the NOx storage component in an amount in the range of from 0.1 to 10 weight-%, more preferably of from 0.5 to 7 weight-%, more preferably of from 1 to 5 weight-%, based on the weight of the second catalytic coating of the second catalyst.

[0075] In case that the second catalyst further comprises a second catalytic coating, it is preferred that the second catalytic coating of the second catalyst is substantially free of palladium, more preferably wherein the second catalytic coating of the second 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 second catalytic coating of the second catalyst is free of palladium. Further, it is preferred that the second catalytic coating of the second catalyst is substantially free of zeolitic materials, more preferably wherein the second catalytic coating of the second catalyst comprises 0.1 g / ft3or less of zeolitic materials, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the second catalytic coating of the second catalyst is free of zeolitic material. Yet further, it is preferred that the second catalytic coating of the second catalyst is present on the inlet side over 30 to 50%, more preferably 40 to 50%, more preferably 45 to 50%, of the axial length of the gasoline particulate filter from the upstream end.

[0076] In case that the second catalyst further comprises a flow-through substrate, it is preferred that the second catalyst further comprises a third catalytic coating. Further, it is preferred that the third catalytic coating comprises one or more zeolitic materials.

[0077] In case that the third catalytic coating comprises one or more zeolitic materials, it is preferred that the one or more zeolitic materials comprised in the third catalytic coating of the second catalyst comprise one or more of Fe and Cu, more preferably wherein the one or more zeolitic materials comprise Fe. Further, it is preferred that the one or more zeolitic materials comprised in the third catalytic coating of the second catalyst comprise iron, wherein the amount of iron comprised in the one or more zeolitic materials, calculated as Fe20s, is more 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 one or more zeolitic materials.

[0078] In case that the second catalyst further comprises a third catalytic coating, it is preferred that the third catalytic coating of the second catalyst is substantially free of Cu, more preferably wherein the third catalytic coating of the second catalyst comprises 0.1 weight-% or less of Cu, preferably 0.01 weight-% or less, more preferably 0.001 weight-% or less, more preferably wherein the third catalytic coating of the second catalyst is free of Cu.

[0079] In case that the third catalytic coating comprises one or more zeolitic materials, it is preferred that the one or more zeolitic materials comprised in the third catalytic coating of the second catalyst are a 12-membered ring pore zeolitic material, wherein the 12-membered ring pore zeolitic material more preferably has a 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 third catalytic coating of the second catalyst has a framework type BEA. Further, it is preferred that from 95 to 100 weight-%, more 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 one or more zeolitic materials comprised in the third catalytic coating of the second 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. In case that the second catalyst further comprises a third catalytic coating, it is preferred that the third catalytic coating of the second catalyst is substantially free of platinum group metal components, more preferably wherein the third catalytic coating of the second catalyst comprises 0.1 g / ft3or less of platinum group metal components, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the third catalytic coating of the second catalyst is free of platinum group metal components. Further, it is preferred that the third catalytic coating of the second catalyst is disposed on the AMOx coating of the second catalyst over 98 to 100%, more preferably 99 to 100%, more preferably 99.5 to 100%, of the flow-through substrate length.

[0080] The present invention further relates 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

[0081] (1 ) providing an exhaust gas stream from a gasoline engine comprising one or more of NOx, ammonia, nitrogen monoxide and one or more hydrocarbons;

[0082] (2) passing the exhaust gas stream provided in (1 ) through the exhaust gas system according to the present invention.

[0083] Further, the present invention relates to a use of an exhaust gas treatment system according to the present invention, for the treatment of an exhaust gas stream from a gasoline engine.

[0084] 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 process 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 process of any one of embodiments 1 , 2, 3 and 4". 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.

[0085] 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

[0086] (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 metal components selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material;

[0087] (ii) a second catalyst, comprising, preferably consisting of, a gasoline particle filter having an inlet end and an outlet end, and comprising a coating for the oxidation of ammonia (AM Ox) disposed on a filter substrate, wherein the coating of the second catalyst comprises one or more platinum group metal components selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material, and wherein the coating of the second catalyst comprises one or more zeolitic materials; wherein the first catalyst according to (i) is located 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.

[0088] 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.

[0089] 3. The exhaust gas treatment system of embodiment 1 or 2, wherein the one or more platinum group metal components of the coating of the first catalyst are platinum, palladium and rhodium.

[0090] 4. The exhaust gas treatment system of any one of embodiments 1 to 3, wherein the coating of the first catalyst comprises the one or more platinum group metal components at a loading, calculated as elemental platinum group metal, in the range of from 1 to 20 g / ft3, preferably in the range of from 2 to 10 g / ft3, more preferably in the range of from 3 to 5 g / ft3, more preferably in the range of from 3.5 to 4.5 g / ft3, more preferably in the range of from 3.8 to 4.2 g / ft3.

[0091] 5. The exhaust gas treatment system of any one of embodiments 1 to 4, wherein the weight ratio of Pt to Pd in the coating of the first catalyst is in the range of from 0.01 :1 to 1 :0.01 , preferably in the range of from 0.1 :1 to 1 :0.1 , more preferably in the range of from 0.5:1 to 1 :0.5, more preferably in the range of from 0.7:1 to 1 :0.7, more preferably in the range of from 0.9:1 to 1 :0.9.

[0092] 6. The exhaust gas treatment system of any one of embodiments 1 to 5, wherein the weight ratio of Rh to Pt in the coating of the first catalyst is in the range of from 0.01 :1 to 0.5:1 , preferably in the range of from 0.05:1 to 0.4:1 , more preferably in the range of from 0.1 :1 to 0.3:1 , more preferably in the range of from 0.15:1 to 0.25:1. 7. The exhaust gas treatment system of any one of embodiments 1 to 6, wherein the weight ratio of Rh to Pd in the coating of the first catalyst is in the range of from 0.01 :1 to 0.5:1 , preferably in the range of from 0.05:1 to 0.4:1 , more preferably in the range of from 0.1 :1 to 0.3:1 , more preferably in the range of from 0.15:1 to 0.25:1.

[0093] 8. The exhaust gas treatment system of any one of embodiments 1 to 7, 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, ceria, 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 thereof, and a mixed oxide thereof, more preferably wherein the support material is alumina.

[0094] 9. The exhaust gas treatment system of any one of embodiments 1 to 8, wherein the support material supporting the platinum group metal component of the coating of the first 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 lanthanum.

[0095] 10. The exhaust gas treatment system of any one of embodiments 1 to 9, 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 cerium 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.

[0096] 11 . The exhaust gas treatment system of embodiment 10, wherein the coating of the first catalyst comprises the oxygen storage compound at a loading in the range of from 0.01 to 3 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 g / in3, more preferably in the range of from 0.3 to 0.9 g / in3, more preferably in the range of from 0.4 to 0.8 g / in3, more preferably in the range of from 0.5 to 0.7 g / in3.

[0097] 12. The exhaust gas treatment system of embodiment 10 or 11 , 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 1 :1 to 5:1 , preferably in the range of from 2:1 to 4:1 , more preferably in the range of from 2.5:1 to 3.5:1 . 13. The exhaust gas treatment system of any one of embodiments 1 to 12, wherein the coating of the first catalyst further comprises a non-zeolitic oxidic material, the non-ze- olitic oxidic material preferably comprises one or more of zirconia, alumina, ceria, titania, silica, lanthana and a mixed oxide comprising two or more of Zr, Al, Ce, Ti, Si, and La, more preferably comprises one or more of zirconia, alumina, lanthana and silica, more preferably comprises one or more of zirconia and lanthana, more preferably comprises zirconia and lanthana.

[0098] 14. The exhaust gas treatment system of any one of embodiments 1 to 13, wherein the coating of the first catalyst comprises the non-zeolitic oxidic material, calculated as the oxide, in the range of from 0.1 to 10 weight-%, preferably of from 0.3 to 5 weight-%, more preferably of from 0.5 to 3 weight-%, based on the weight of the coating of the first catalyst.

[0099] 15. The exhaust gas treatment system of any one of embodiments 1 to 14, wherein the non-zeolitic oxidic material is zirconia and wherein the coating of the first catalyst comprises zirconia, calculated as the oxide, in the range of from 0.1 to 7 weight-%, preferably of from 0.3 to 5 weight-%, more preferably of from 0.5 to 3 weight-%, based on the weight of the coating of the first catalyst.

[0100] 16. The exhaust gas treatment system of any one of embodiments 1 to 15, wherein the non-zeolitic oxidic material is lanthana and wherein the coating of the first catalyst comprises lanthana, calculated as the oxide, in the range of from 0.1 to 8 weight-%, preferably of from 0.5 to 5 weight-%, more preferably of from 1 to 3 weight-%, based on the weight of the coating of the first catalyst.

[0101] 17. The exhaust gas treatment system of any one of embodiments 1 to 16, 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 alkali earth metal and an oxide of an alkali 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, Cs and mixtures of two or more thereof, 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.

[0102] 18. The exhaust gas treatment system of embodiment 17, wherein the coating of the first catalyst comprises the NOx storage component in an amount in the range of from 0.1 to 10 weight-%, preferably of from 0.5 to 7 weight-%, more preferably of from 1 to 5 weight-%, based on the weight of the coating of the first catalyst.

[0103] 19. The exhaust gas treatment system of any one of embodiments 1 to 18, 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 coating of the first catalyst consists of one or more platinum group metal components supported on a support material, preferably an oxygen storage compound as defined in embodiment 10 to 12, more preferably a non-zeolitic oxidic material as defined in embodiment 13 to 16, and more preferably an NOx storage component as defined in embodiment 17 or 18. The exhaust gas treatment system of any one of embodiments 1 to 19, wherein the coating of the first catalyst comprises a first catalytic coating comprising palladium supported on a first support material, a second catalytic coating comprising platinum supported on second a support material, and a third catalytic coating comprising rhodium supported on a third support material. The exhaust gas treatment system of embodiment 20, wherein the first support material of the palladium comprised in the first catalytic coating 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, ceria, zirconia, a mixture of two or more thereof, and a mixed oxide of two or more thereof, more preferably wherein the first support material is ceria-zirconia. The exhaust gas treatment system of embodiment 20 or 21 , wherein the first catalytic coating is disposed over 20 to 70%, preferably over 30 to 60%, more preferably over 40 to 50% from the inlet end towards the outlet end of the substrate. The exhaust gas treatment system of any one of embodiments 20 to 22, wherein the second support material of the platinum comprised in the second catalytic coating 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, silica, titania, a mixture of two or more thereof, and a mixed oxide of two or more thereof, more preferably wherein the second support material is alumina. The exhaust gas treatment system of any one of embodiments 20 to 23, wherein the second support material 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 lanthanum. The exhaust gas treatment system of any one of embodiments 20 to 24, wherein the second catalytic coating is disposed over 30 to 80%, preferably over 40 to 70, more preferably over 50 to 60%, from the outlet end towards the inlet end of the substrate. 26. The exhaust gas treatment system of any one of embodiments 20 to 25, wherein the third support material of the rhodium comprised in the third catalytic coating 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, silica, titania, a mixture of two or more thereof, and a mixed oxide of two or more thereof, more preferably wherein the third support material is alumina.

[0104] 27. The exhaust gas treatment system of any one of embodiments 20 to 26, wherein the third support material further 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 lanthanum.

[0105] 28. The exhaust gas treatment system of any one of embodiments 20 to 27, wherein the third catalytic coating is disposed on the first and second catalytic coating over 98 to 100%, preferably 99 to 100%, more preferably 99.5 to 100%, of the substrate axial length.

[0106] 29. The exhaust gas treatment system of any one of embodiments 1 to 19, wherein the coating of the first catalyst comprises a first catalytic coating comprising palladium supported on a first support material and platinum supported on second a support material, and a second catalytic coating comprising rhodium supported on a third support material.

[0107] 30. The exhaust gas treatment system of embodiment 29, wherein the first support material of the palladium comprised in the first catalytic coating 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, ceria, zirconia, a mixture of two or more thereof, and a mixed oxide of two or more thereof, more preferably wherein the first support material is ceria-zirconia.

[0108] 31 . The exhaust gas treatment system of embodiment 29 or 30, wherein the second support material of the platinum comprised in the first catalytic coating 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, silica, titania, a mixture of two or more thereof, and a mixed oxide of two or more thereof, more preferably wherein the second support material is alumina. 32. The exhaust gas treatment system of any one of embodiments 29 to 31 , wherein the second support material 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 lanthanum.

[0109] 33. The exhaust gas treatment system of any one of embodiments 29 to 32, wherein the first catalytic coating is disposed over 98 to 100%, preferably 99 to 100%, more preferably 99.5 to 100%, of the substrate axial length.

[0110] 34. The exhaust gas treatment system of any one of embodiments 29 to 23, wherein the third support material of the rhodium comprised in the second catalytic coating 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, silica, titania, a mixture of two or more thereof, and a mixed oxide of two or more thereof, more preferably wherein the third support material is alumina.

[0111] 35. The exhaust gas treatment system of any one of embodiments 29 to 34, wherein the third support material further 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 lanthanum.

[0112] 36. The exhaust gas treatment system of any one of embodiments 29 to 35, wherein 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.

[0113] 37. The exhaust gas treatment system of any one of embodiments 1 to 36, wherein the substrate of the first catalyst is a flow-through substrate, preferably a ceramic flow- through substrate, wherein the ceramic flow-through 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 alumi- nasilicate.

[0114] 38. The exhaust gas treatment system of any one of embodiments 1 to 37, wherein the first catalyst consists of the substrate and the coating. 39. The exhaust gas treatment system of any one of embodiments 1 to 38, wherein the gasoline particle filter is a wall-flow filter, preferably a honeycomb wall-flow filter.

[0115] 40. The exhaust gas treatment system of embodiment 39, 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.

[0116] 41 . The exhaust gas treatment system of any one of embodiments 1 to 40, wherein the one or more platinum group metal components of the AMOx coating of the second catalyst are selected from the group consisting of Pt, Rh, and mixtures thereof, preferably wherein the one or more platinum group metal components of the AMOx coating of the third catalyst is Pt.

[0117] 42. The exhaust gas treatment system of any one of embodiments 1 to 41 , wherein the platinum group metal loading of the coating of the second catalyst is in the range of from 0.1 to 100 g / ft3, preferably in the range of from 1 to 50 g / ft3, more preferably in the range of from 1 to 30 g / ft3, more preferably in the range of from 2 to 25 g / ft3.

[0118] 43. The exhaust gas treatment system of any one of embodiments 1 to 42, wherein the second catalyst is substantially free of palladium, preferably wherein the second 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 second catalyst is free of palladium.

[0119] 44. The exhaust gas treatment system of any one of embodiments 1 to 43, wherein the coating of the second catalyst is substantially free of palladium, preferably wherein the catalytic coating of the second 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 second catalyst is free of palladium.

[0120] 45. The exhaust gas treatment system of any one of embodiments 1 to 44, wherein the loading of the coating of the second catalyst is in the range of from 0.1 to 25 g / in3, preferably in the range of from 0.5 to 10 g / in3, more preferably in the range of from 1 to 5 g / in3, more preferably in the range of from 1 to 3 g / in3, more preferably in the range of from 1.2 to 2 g / in3.

[0121] 46. The exhaust gas treatment system of any one of embodiments 1 to 45, wherein the support material of the coating of the second 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 any one of embodiments 1 to 46, wherein the support material of the coating of the second 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 lanthanum. The exhaust gas treatment system of embodiment 47, wherein the content of the one or more rare earth metals of the support material of the coating of the second 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 1 to 50 weight-%, more preferably of from 1 to 40 weight-%, more preferably of from 1 to 35 weight-%, based on the total weight of the support material of the coating of the second catalyst. The exhaust gas treatment system of embodiment 47 or 48, wherein the one or more rare earth metals is cerium, and wherein the cerium content of the support material of the coating of the second catalyst is in the range of from 0.1 to 80 weight-%, preferably of from 5 to 70 weight-%, more preferably of from 10 to 50 weight-%, more preferably of from 20 to 40 weight-%, more preferably of from 25 to 35 weight-%, on the total weight of the support material of the coating of the second catalyst. The exhaust gas treatment system of any one of embodiments 1 to 49, wherein the coating of the second catalyst comprises the support material in the range of from 0.1 to 5 g / in3, preferably in the range of from 0.5 to 2 g / in3, more preferably in the range of from 0.8 to 1.7 g / in3, more preferably in the range of from 1 to 1.5 g / in3. The exhaust gas treatment system of any one of embodiments 1 to 50, wherein the coating of the second catalyst further 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. The exhaust gas treatment system of embodiment 51 , wherein the cerium content of the oxygen storage compound in the coating of the second catalyst is in the range of from 1 to 81 .46 weight-%, preferably in the range of from 5 to 70 weight-%, more preferably in the range of from 10 to 60 weight-%, more preferably in the range of from 20 to 50 weight-%, more preferably in the range of from 30 to 45 weight-%, based on the total weight of the oxygen storage compound of the coating of the second catalyst. 53. The exhaust gas treatment system of any one of embodiments 1 to 52, wherein the one or more zeolitic materials comprised in the coating of the second catalyst comprise one or more of Fe and Cu, preferably wherein the one or more zeolitic materials comprise Fe.

[0122] 54. The exhaust gas treatment system of any one of embodiments 1 to 53, wherein the zeolitic material comprised in the coating of the second catalyst 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.

[0123] 55. The exhaust gas treatment system of any one of claims 1 to 54, wherein the coating of the second catalyst is substantially free of Cu, preferably wherein the coating of the second catalyst comprises 0.1 weight-% or less of Cu, preferably 0.01 weight-% or less, more preferably 0.001 weight-% or less, more preferably wherein the coating of the second catalyst is free of Cu.

[0124] 56. The exhaust gas treatment system of any one of embodiments 1 to 55, wherein the one or more zeolitic materials comprised in the coating of the second catalyst is a 12- membered ring pore zeolitic material, wherein the 12-membered ring pore zeolitic material preferably has a 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 second catalyst has a framework type BEA.

[0125] 57. The exhaust gas treatment system of any one of embodiments 1 to 56, 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 one or more zeolitic materials comprised in the coating of the second catalyst consists of Si, Al, and O, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO2:AI2C>3, 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.

[0126] 58. The exhaust gas treatment system of any one of embodiments 1 to 57, wherein the coating of the second catalyst 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, and mixtures thereof, more preferably wherein the non-zeolitic oxidic material is zirconia.

[0127] 59. The exhaust gas treatment system of embodiment 58, wherein the coating of the second catalyst comprises the non-zeolitic oxidic material in an amount, calculated as the oxide, in the range of from 0.1 to 8 weight-%, preferably of from 0.5 to 5 weight-%, more preferably of from 1 to 3 weight-%, based on the washcoat loading of the coating of the second catalyst.

[0128] 60. The exhaust gas treatment system of any one of embodiments 1 to 59, wherein the coating of the second catalyst is substantially free of alkali earth metal oxides and alkali metal oxides, wherein preferably the coating comprises 0.1 g / ft3or less of alkali earth metal oxides and alkali metal oxides, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the coating of the second catalyst is free of alkali earth metal oxides and alkali metal oxides.

[0129] 61 . The exhaust gas treatment system of any one of embodiments 1 to 60, wherein the coating of the second catalyst is substantially free of barium, wherein preferably the coating of the second 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 second catalyst is free of barium.

[0130] 62. The exhaust gas treatment system of any one of embodiments 1 to 61 , wherein the AMOx coating of the second catalyst is disposed on the inlet side over 98 to 100%, preferably 99 to 100%, more preferably 99.5 to 100%, of the axial length of the gasoline particulate filter from the upstream end.

[0131] 63. The exhaust gas treatment system of embodiment 62, wherein no coating is disposed on the outlet side of the gasoline particulate filter from the downstream end.

[0132] 64. The exhaust gas treatment system of any one of embodiments 1 to 61 , wherein the AMOx coating of the second catalyst is disposed on the outlet side over 30 to 50%, preferably 40 to 50%, more preferably 45 to 50%, of the axial length of the gasoline particulate filter from the downstream end.

[0133] 65. The exhaust gas treatment system of any one of embodiments 1 to 61 , wherein the second catalyst further comprises a flow-through substrate, wherein the flow-through substrate is downstream of the gasoline particulate filter. The exhaust gas treatment system of embodiment 65, wherein the outlet end of the gasoline particulate filter is adjacent to the flow-through substrate and wherein between the outlet end of the gasoline particulate filter and the flow-through substrate no substrate or filter is located in the second catalyst. The exhaust gas treatment system of embodiment 65 or 66, wherein the flow-through substrate of the second catalyst is a honeycomb flow-through substrate, preferably a ceramic honeycomb flow-through substrate, wherein the ceramic honeycomb flow- through substrate preferably comprises, more preferably consists of, cordierite, cordi- erite-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 65 to 67, wherein the AMOx coating of the second catalyst is disposed on the flow-through substrate of the second catalyst over 98 to 100%, preferably 99 to 100%, more preferably 99.5 to 100%, of the substrate length of the flow-through substrate. The exhaust gas treatment system of any one of embodiments 64 to 68, wherein the second catalyst further comprises a second catalytic coating. The exhaust gas treatment system of embodiment 69, wherein the second catalytic coating of the second catalyst comprises one or more platinum group metal components, wherein preferably the one or more platinum group metal components are selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, more preferably from the group consisting of Pt, Rh, and mixtures thereof, more preferably wherein the one or more platinum group metal components are Pt and Rh. The exhaust gas treatment system of embodiment 69 or 70, wherein the platinum group metal loading of the second catalytic coating of the second catalyst is in the range of from 0.1 to 100 g / ft3, preferably in the range of from 1 to 50 g / ft3, more preferably in the range of from 1 to 30 g / ft3, more preferably in the range of from 2 to 25 g / ft3. The exhaust gas treatment system of any one of embodiments 69 to 71 , wherein the one or more platinum group metal components of the second catalytic coating of the second catalyst are supported on a support material. The exhaust gas treatment system of embodiment 72, wherein the support material supporting the one or more platinum group metal components of the second catalytic 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, ceria, 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 thereof, and a mixed oxide thereof.

[0134] 74. The exhaust gas treatment system of embodiment 72 or 73, wherein the support material supporting the one or more platinum group metal component of the second catalytic coating of the second 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.

[0135] 75. The exhaust gas treatment system of embodiment 74, wherein the content of the one or more rare earth metals of the support material of the second catalytic coating of the second 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 1 to 50 weight-%, more preferably of from 1 to 40 weight-%, more preferably of from 1 to 35 weight-%, based on the total weight of the support material of the second catalytic coating of the second catalyst.

[0136] 76. The exhaust gas treatment system of embodiment 74 or 75, wherein the one or more rare earth metals is cerium, and wherein the cerium content of the support material of the second catalytic coating of the second catalyst is in the range of from 1 to 80 weight-%, preferably of from 10 to 70 weight-%, more preferably of from 15 to 60 weight-%, more preferably of from 20 to 50 weight-%, more preferably of from 30 to 45 weight-%, based on the total weight of the support material of the second catalytic coating of the second catalyst.

[0137] 77. The exhaust gas treatment system of any one of embodiments 74 to 76, wherein the one or more rare earth metals is lanthanum, and wherein the lanthanum content of the support material of the coating of the second catalyst is in the range of from 0.1 to 10 weight-%, preferably of from 1 to 9 weight-%, more preferably of from 1 to 8 weight-%, more preferably of from 2 to 7 weight-%, more preferably of from 3 to 6 weight-%, based on the total weight of the support material of the second catalytic coating of the second catalyst.

[0138] 78. The exhaust gas treatment system of any one of embodiments 70 to 77, wherein the one or more platinum group metal components are platinum and rhodium, and wherein rhodium and at least a part of the platinum are supported on the same support material.

[0139] 79. The exhaust gas treatment system of embodiment 78, wherein the weight ratio of platinum and rhodium supported in the same support material is in the range of from 0.1 :1 to 5:1 , preferably in the range of from 0.5:1 to 3:1 , more preferably in the range of from 0.8:1 to 2:1 , more preferably in the range of from 1 :1 to 1.5:1 , more preferably in the range of from 1.1 :1 to 1.4:1 , more preferably in the range of from 1.2:1 to 1.3:1 . The exhaust gas treatment system of any one of embodiments 69 to 79, wherein the second catalytic 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, lanthana and a mixed oxide comprising two or more of Zr, Al, Ce, Ti, Si, and La, more preferably comprises one or more of zirconia, alumina, lanthana and silica, more preferably comprises one or more of zirconia and lanthana, more preferably comprises zirconia. The exhaust gas treatment system of embodiment 80, wherein the second catalytic coating of the second catalyst comprises the non-zeolitic oxidic material, calculated as the oxide, in the range of from 0.1 to 10 weight-%, preferably of from 0.3 to 5 weight- %, more preferably of from 0.5 to 3 weight-%, based on the weight of the coating of the first catalyst. The exhaust gas treatment system of any one of embodiments 69 to 81 , wherein the second catalytic coating of the second catalyst further comprises an NOx storage component, preferably wherein the NOx storage component comprises one or more of an oxide of an alkali earth metal and an oxide of an alkali 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, Cs and mixtures of two or more thereof, 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. The exhaust gas treatment system of embodiment 82, wherein the second catalytic coating of the second catalyst comprises the NOx storage component in an amount in the range of from 0.1 to 10 weight-%, preferably of from 0.5 to 7 weight-%, more preferably of from 1 to 5 weight-%, based on the weight of the second catalytic coating of the second catalyst. The exhaust gas treatment system of any one of embodiments 69 to 83, wherein the second catalytic coating of the second catalyst is substantially free of palladium, preferably wherein the second catalytic coating of the second 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 second catalytic coating of the second catalyst is free of palladium. The exhaust gas treatment system of any one of embodiments 69 to 84, wherein the second catalytic coating of the second catalyst is substantially free of zeolitic materials, preferably wherein the second catalytic coating of the second catalyst comprises 0.1 g / ft3or less of zeolitic materials, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the second catalytic coating of the second catalyst is free of zeolitic material.

[0140] 86. The exhaust gas treatment system of any one of embodiments 69 to 85, wherein the second catalytic coating of the second catalyst is present on the inlet side over 30 to 50%, preferably 40 to 50%, more preferably 45 to 50%, of the axial length of the gasoline particulate filter from the upstream end.

[0141] 87. The exhaust gas treatment system of any one of embodiments 65 to 86, wherein the second catalyst further comprises a third catalytic coating.

[0142] 88. The exhaust gas treatment system of embodiment 87, wherein the third catalytic coating comprises one or more zeolitic materials.

[0143] 89. The exhaust gas treatment system of embodiment 88, wherein the one or more zeolitic materials comprised in the third catalytic coating of the second catalyst comprise one or more of Fe and Cu, preferably wherein the one or more zeolitic materials comprise Fe.

[0144] 90. The exhaust gas treatment system of embodiment 88 or 89, wherein the one or more zeolitic materials comprised in the third catalytic coating of the second catalyst comprise iron, wherein the amount of iron comprised in the one or more zeolitic materials, 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 one or more zeolitic materials.

[0145] 91 . The exhaust gas treatment system of any one of embodiments 87 to 90, wherein the third catalytic coating of the second catalyst is substantially free of Cu, preferably wherein the third catalytic coating of the second catalyst comprises 0.1 weight-% or less of Cu, preferably 0.01 weight-% or less, more preferably 0.001 weight-% or less, more preferably wherein the third catalytic coating of the second catalyst is free of Cu.

[0146] 92. The exhaust gas treatment system of any one of embodiments 88 to 91 , wherein the one or more zeolitic materials comprised in the third catalytic coating of the second catalyst are a 12-membered ring pore zeolitic material, wherein the 12-membered ring pore zeolitic material preferably has a 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 third catalytic coating of the second catalyst has a framework type BEA. 93. The exhaust gas treatment system of any one of embodiments 88 to 92, 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 one or more zeolitic materials comprised in the third catalytic coating of the second 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.

[0147] 94. The exhaust gas treatment system of any one of embodiments 87 to 93, wherein the third catalytic coating of the second catalyst is substantially free of platinum group metal components, preferably wherein the third catalytic coating of the second catalyst comprises 0.1 g / ft3or less of platinum group metal components, more preferably 0.01 g / ft3or less, more preferably 0.001 g / ft3or less, more preferably wherein the third catalytic coating of the second catalyst is free of platinum group metal components.

[0148] 95. The exhaust gas treatment system of any one of embodiments 87 to 94, wherein the third catalytic coating of the second catalyst is disposed on the AMOx coating of the second catalyst over 98 to 100%, preferably 99 to 100%, more preferably 99.5 to 100%, of the flow-through substrate length.

[0149] 96. 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

[0150] (1 ) providing an exhaust gas stream from a gasoline engine comprising one or more of NOx, ammonia, nitrogen monoxide and one or more hydrocarbons;

[0151] (2) passing the exhaust gas stream provided in (1) through the exhaust gas system according to any one of embodiments 1 to 95.

[0152] 97. Use of an exhaust gas treatment system according to any one of embodiments 1 to 95, for the treatment of an exhaust gas stream from a gasoline engine.

[0153] The present invention is further illustrated by the following examples.

[0154] EXAMPLES

[0155] Reference Example 1 : Determination of the volume-based particle size distribution Dv90

[0156] 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 multielement detection range comprising 5 modules covering 0.1-875 microns.

[0157] Reference Example 2: A three-way conversion (TWC) catalyst

[0158] An aqueous mixture of palladium salt precursors were impregnated on high porosity ceria-zirconia. The obtained Pd on ceria-zirconia (solid content: 60-75 wt.-%) was calcined at 400-600 °C for 2-4 hours. An aqueous mixture of platinum salt precursors were impregnated on high porosity La-doped alumina . The obtained Pt on La-doped alumina (solid content: 60-75 wt.-%) was calcined at 400-600 °C for 2-4 hours. An aqueous mixture of rhodium salt precursors were impregnated on high porosity La-doped alumina . The obtained Rh on La-doped alumina (solid content: 60-75 wt.-%) was calcined at 400-600 °C for 2-4 hours.

[0159] Three slurries were prepared from the calcined PGM-containing powders by mixing the corresponding calcined PGM-containing powder, distilled water, n-octanol and a precursor of baria, lanthana 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, the amount of lanthana precursor was calculated such that the loading of La2Os, from said source, in the catalyst after calcination was 1-3 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 0.5-3 wt.-% based on the weight of the coating.

[0160] The slurry solid contents were adjusted to 35-45 wt.-% to enhance pH and viscosity measurements and wet milling. After milling, the pH of the slurries was adjusted by adding nitric acid to have a pH of 3-5. The particle size distribution (Dv90) of the slurries after milling was of 10-20 micrometers.

[0161] The obtained slurry comprising Pd was disposed over 50% of the non-coated ceramic honeycomb flow through substrate (diameter: 4.16 inches x length: 4.29 inches, cylindrical shaped substrate with 750 / (2.5)2cells per square centimeter and 0.0635 millimeter (2.5 mil) wall thickness) from the inlet end and dried. The obtained slurry comprising Pt was disposed over 50% of the ceramic honeycomb flow through substrate from the outlet end and dried.

[0162] Then the obtained slurry comprising Rh was disposed over the entire length of the coated ceramic honeycomb flow through substrate, dried at 120- 180°C and further calcined at 400-600 °C in air.

[0163] Comparative Example 1 : An exhaust gas treatment system not according to the present invention

[0164] The exhaust gas treatment system of Comparative Example 1 comprises the catalyst of Reference Example 1 (TWC catalyst) as Catalyst 1 and a bare filter as Catalyst 2, wherein Catalyst 1 is located upstream of Catalyst 2. No catalysts are present between Catalyst 1 and 2 and Catalyst 1 is a close coupled catalyst. The system is illustrated in Figure 1 .

[0165] Reference Example 3: An ammonia oxidation (AMOx on GPF) catalyst

[0166] An aqueous mixture of a Pt precursor was impregnated on a high surface area and porous oxidic ceria-doped alumina (30 wt.-% Ce content of the doped alumina) in an aqueous medium, followed by thermal fixation of the metal on the support via calcination at 350-450 °C in air. The calcined powder was used to prepare a slurry with a solid content of 35-45%. Said slurry was wet milled such as to obtain a Dv90 of 4-8 micrometers.

[0167] A second mixture of distilled water and 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 (1-3 wt.-%) was added to said mixture under constant mixing. The solid content of the obtained slurry was 35-45%. Said slurry was wet milled such as to obtain a Dv90 of 4-8 micrometers.

[0168] Both slurries were blended and thoroughly stirred before coating. The obtained slurry was then disposed over the entire length from the inlet of a high porosity ceramic wall-flow filter substrate (diameter: 4.33 inches x length: 4.33 inches, cylindrical shaped substrate with a cell density / wall thickness of 300 / 8 (cells per square inch / mil), dried at 120-180 °C and calcined at 350-400 °C in air. The total Pt-loading is 2-25 g / ft3and the washcoat loading of the coating was 1.2-2.0 g / in3.

[0169] Example 1 : An exhaust gas treatment system according to the present invention

[0170] The exhaust gas treatment system of Example 1 comprises the catalyst of Reference Example 1 (TWC catalyst) as Catalyst 1 and the catalyst of Reference Example 3 (AMOx) as Catalyst 2, wherein Catalyst 1 is located upstream of Catalyst 2. No catalysts are present between Catalyst 1 and 2 and Catalyst 1 is a close coupled catalyst. The system is illustrated in Figure 1 .

[0171] Reference Example 4: An ammonia oxidation (FWC / AMOx on GPF) catalyst

[0172] Inlet coating:

[0173] An aqueous mixture of a Pt precursor was impregnated on a high surface area and porous oxidic ceria-doped zirconia (35-45 wt.-% Ce content of the doped zirconia) in an aqueous medium, followed by thermal fixation of the metal on the support via calcination at 350-450 °C in air. A second aqueous mixture of a Pt precursor and Rh precursor was impregnated on a high surface area and porous oxidic lanthanum-doped alumina (3-6 wt.-% La content of the doped alumina) in an aqueous medium, followed by thermal fixation of the metal on the support via calcination at 350-450 °C in air. The calcined powders were used to prepare a slurry with a solid content of 35-45%. Zirconia and baria (0.5-3 wt.-% zirconia and 1-5 wt.-% baria) were added during slurry preparation. Said slurry was wet milled such as to obtain a Dv90 of 4-8 micrometers.

[0174] Outlet coating:

[0175] The outlet coating was prepared according to Reference Example 3.

[0176] The inlet coating was then disposed over 50% of the axial length from the inlet of a high porosity ceramic wall-flow filter substrate (diameter: 4.33 inches x length: 4.33 inches, cylindrical shaped substrate with a cell density / wall thickness of 300 / 8 (cells per square inch / mil), followed by disposition of the outlet coating over 50% of the axial length from the outlet. The coated substrate was dried at 120-180 °C and calcined at 350-400 °C in air. The total Pt-loading was 2-25 g / ft3and the washcoat loading of the coating was 1.2-2.0 g / in3.

[0177] Example 2: An exhaust gas treatment system according to the present invention

[0178] The exhaust gas treatment system of Example 2 comprises the catalyst of Reference Example 1 (TWC catalyst) as Catalyst 1 and the catalyst of Reference Example 4 (FWC / AMOx) as Catalyst 2, wherein Catalyst 1 is located upstream of Catalyst 2. No catalysts are present between Catalyst 1 and 2 and Catalyst 1 is a close coupled catalyst. The system is illustrated in Figure 1.

[0179] Reference Example 5: An ammonia oxidation (FWC / AMOx) catalyst

[0180] The catalyst is composed of two different monoliths, wherein the first monolith is a half-coated filter and the second monolith is a slice of a coated flow-through catalyst placed directly behind the filter.

[0181] Gasoline particle filter:

[0182] An aqueous mixture of a Pt precursor was impregnated on a high surface area and porous oxidic ceria-doped zirconia (35-45 wt.-% Ce content of the doped zirconia) in an aqueous medium, followed by thermal fixation of the metal on the support via calcination at 350-450 °C in air. A second aqueous mixture of a Pt precursor and Rh precursor was impregnated on a high surface area and porous oxidic lanthanum-doped alumina (3-6 wt.-% La content of the doped alumina) in an aqueous medium, followed by thermal fixation of the metal on the support via calcination at 350-450 °C in air. The calcined powders were used to prepare a slurry with a solid content of 35-45%. Zirconia, baria and alumina (0.5-3 wt.-% zirconia and 1-5 wt.-% baria) were added during slurry preparation. Said slurry was wet milled such as to obtain a Dv90 of 4-8 micrometers.

[0183] The coating was then disposed over 50% of the axial length from the inlet of a first high porosity ceramic wall-flow filter substrate (diameter: 4.33 inches x length: 4.33 inches, cylindrical shaped substrate with a cell density / wall thickness of 300 / 8 (cells per square inch / mil), dried at 120- 180 °C and calcined at 350-400 °C in air. The total Pt-loading is 2-25 g / ft3and the loading of the coating was 1 .2-2.0 g / in3.

[0184] Flow-through substrate:

[0185] PGM-containing bottom coating:

[0186] An aqueous mixture of a Pt precursor was impregnated on a high surface area and porous oxidic support in an aqueous medium. The solid content of the obtained slurry was 50-70%. Said slurry was wet milled such as to obtain a Dv90 of 10-25 micrometers.

[0187] A second mixture of distilled water and Fe-BEA zeolite was prepared. The solid content of the obtained slurry was 30-50%. Both slurries were mixed and wet milled such as to obtain a Dv90 of 2-15 micrometers.

[0188] 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 2-4 g / in3.

[0189] PGM-free top coating:

[0190] 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 mixed with water under constant mixing. The solid content of the obtained slurry was 20-40%. The slurry was dispersed and mixed such as to obtain a Dv90 of 2-12 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.

[0191] Example 4: Testing of the systems according to Examples 1-3 and Comparative Example 1

[0192] In the different systems, Catalyst 1 (TWC) is located in the same can in combination with a different downstream component in Comparative Example 1 and Examples 1-3.

[0193] The close-coupled catalyst was aged separately in a 5-leg spider configuration using the ZDAKW engine aging procedure, wherein the aging duration was 200 h and the temperature at the catalyst inlet was 950 °C. The underfloor catalysts were aged together in a separate aging run at 840 °C for 10 h in a gas atmosphere comprising 5% 02 and 10% H2O, and regenerated in a reducing gas atmosphere (2% H2) at 840°C for 10 min on an engine bench. The catalyst systems were mounted on the exhaust line of a Euro-7 vehicle and evaluated on a chassis dyno test cell using a RDE cycle in combination with the US06 dynamic test cycle. Prior to testing, the vehicle was pre-conditioned at 0°C.

[0194] Figures 2-5 present the cumulated NH3, CO, HC and NOx emissions for each tested system using the US06 dynamic test cycle collected on the vehicle as described above.

[0195] 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. As may be taken from Figure 3, the cumulated HC emissions are significantly higher for the comparative system compared to the inventive systems of Examples 1-3. The best results were obtained with the system of Examples 1 and 3.

[0196] Further, as may be taken from Figures 4 and 5, the cumulated CO and NOx emissions obtained with the comparative system are higher compared to those of the inventive systems. The best results were obtained with the system of Example 2.

[0197] Description of the figures

[0198] Figure 1 shows a schematic of exhaust gas treatment systems according to Examples 1-3 and comparative Example 1 .

[0199] Figure 2 shows the cumulated NH3 emissions obtained with the systems of Examples 1-3 and comparative Example 1 .

[0200] Figure 3 shows the cumulated HC emissions obtained with the systems of Examples 1-3 and comparative Example 1 .

[0201] Figure 4 shows the cumulated CO emissions obtained with the systems of Examples 1-3 and comparative Example 1 .

[0202] Figure 5 shows the cumulated NOx emissions obtained with the systems of Examples 1-3 and comparative Example 1.

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 metal components 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, comprising a gasoline particle filter having an inlet end and an outlet end, and comprising a coating for the oxidation of ammonia (AMOx) disposed on a filter substrate, wherein the coating of the second catalyst comprises one or more platinum group metal components selected from the group consisting of Pt, Pd, Rh, and mixtures of two or more thereof, supported on a support material, and wherein the coating of the second catalyst comprises one or more zeolitic materials; wherein the first catalyst according to (i) is located 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.

2. The exhaust gas treatment system of claim 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.

3. The exhaust gas treatment system of claim 1 or 2, wherein the gasoline particle filter is a wall-flow filter.

4. The exhaust gas treatment system of any one of claims 1 to 3, wherein the loading of the coating of the second catalyst is in the range of from 0.1 to 25 g / in3.

5. The exhaust gas treatment system of any one of claims 1 to 4, wherein the support material of the coating of the second 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.

6. The exhaust gas treatment system of any one of claims 1 to 5, wherein the coating of the second catalyst further comprises an oxygen storage compound.

7. The exhaust gas treatment system of any one of claims 1 to 6, wherein the one or more zeolitic materials comprised in the coating of the second catalyst comprise one or more of Fe and Cu.

8. The exhaust gas treatment system of any one of claims 1 to 7, wherein the one or more zeolitic materials comprised in the coating of the second catalyst is a 12-mem- bered ring pore zeolitic material.

9. The exhaust gas treatment system of any one of claims 1 to 8, wherein the coating of the second catalyst 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.

10. The exhaust gas treatment system of any one of claims 1 to 9, wherein the AMOx coating of the second catalyst is disposed on the inlet side over 98 to 100% of the axial length of the gasoline particulate filter from the upstream end.11 . The exhaust gas treatment system of any one of claims 1 to 9, wherein the AMOx coating of the second catalyst is disposed on the outlet side over 30 to 50% of the axial length of the gasoline particulate filter from the downstream end.

12. The exhaust gas treatment system of any one of claims 1 to 9, wherein the second catalyst further comprises a flow-through substrate, wherein the flow-through substrate is downstream of the gasoline particulate filter.

13. The exhaust gas treatment system of claim 12, wherein the outlet end of the gasoline particulate filter is adjacent to the flow-through substrate and wherein between the outlet end of the gasoline particulate filter and the flow-through substrate no substrate or filter is located in the second catalyst.

14. 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 one or more hydrocarbons;(2) passing the exhaust gas stream provided in (1) through the exhaust gas system according to any one of claims 1 to 13.

15. Use of an exhaust gas treatment system according to any one of claims 1 to 13, for the treatment of an exhaust gas stream from a gasoline engine.

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