Catalytic article and exhaust gas treatment systems

Description

[0001] The present invention relates generally to the fields of selective catalytic reduction catalysts and oxidation catalysts. In particular, the present invention relates to an exhaust gas treatment system for treating an exhaust gas stream exiting a dieselengine. Further, the present invention relates to processes for the preparation of said system.

[0002] Harmful components of nitrogen oxides (NO x ) lead to atmospheric pollution. NO x is contained in exhaust gases, such as from internal combustion engines (e.g., in automobiles and trucks), from combustion installations (e.g., power stations heated by natural gas, oil, or coal), and from nitric acid production plants. Various treatment methods are used to lower NO x in exhaust gases and thus decrease atmospheric pollution. One type of treatment involves catalytic reduction of nitrogen oxides. There are two processes: (1) a nonselective reduction process wherein carbon monoxide, hydrogen, or a lower hydrocarbon is used as a reducing agent; and (2) a selective reduction process wherein ammonia or an ammonia precursor is used as a reducing agent. In the selective reduction process, a high degree of nitrogen oxide removal can be achieved with a small amount of reducing agent.

[0003] The selective reduction process is referred to as a SCR (Selective Catalytic Reduction) process. The SCR process uses catalytic reduction of nitrogen oxides with a reductant (e.g. ammonia or ammonia precursor) in the presence of atmospheric oxygen, resulting in the formation predominantly of nitrogen and steam:         4 NO + 4 NH 3 +O 2 → 4 N 2 + 6 H 2 O (standard SCR reaction)         2 NO 2 + 4 NH 3 → 3 N 2 + 6 H 2 O (slow SCR reaction)         NO + NO 2 + 2NH 3 → 2 N 2 + 3 H 2 O (fast SCR reaction)

[0004] This process is considered one of the most viable techniques for the removal of nitrogen oxides from engine exhaust gas. In a typical exhaust gas, the nitrogen oxides are mainly composed of NO (> 90 %), which is converted by the SCR catalyst into nitrogen and water in the presence of ammonia (standard SCR reaction). NH 3 is one of the most effective reductants although urea can also be used as an ammonia precursor. Generally, catalysts employed in the SCR process should have good catalytic activity over a wide range of temperature, for example, from below 200 °C to 600 °C or higher. Higher temperatures are commonly encountered during the regeneration of soot filters and during the regeneration of SCR catalysts. For soot filters, regeneration refers to the periodic need to remove accumulated soot within the filter. Temperatures greater than 500 °C are needed for typically 20 minutes or more to effectively burn soot. Such temperatures are not encountered during normal engine operation.

[0005] Hydrocarbons, usually as fuel or partially combusted fuel, are typically present in the exhaust and oxidized across a dedicated oxidation catalyst to create the heat necessary to oxidize the soot collected in the filter. Depending on the location of the SCR catalyst relative to the filter, the SCR catalyst could be exposed to high hydrocarbon concentrations, e.g., if the SCR catalyst is positioned between the source of the hydrocarbons, such as the engine, and the DOC installed to oxidize these hydrocarbons for heat generation. Such an arrangement, with the SCR very close to the engine, is contemplated to take advantage of faster heating during cold starts. The term "close coupled" is often used and defined below. For SCR catalysts, regeneration does not have the same implication as with filters. In this case, minor components of the exhaust gas either collect or interact with the SCR catalyst, reducing the effectiveness of the catalyst over time. To maintain high efficiency, it is necessary to periodically remove these contaminants. For example, sulfur oxides can react with ammonia to form ammonium sulfates, which block active sites on the catalyst, leading to activity loss. Also, prolonged operation of SCR catalysts at temperature below about 300°C can lead to the accumulation of HCs on the catalyst surface. Eventually these hydrocarbons also block active sites, leading to a loss in catalytic activity.

[0006] Like for filters, periodic higher temperatures are necessary to remove these and other contaminants to maintain high catalytic efficiency. Achieving temperatures to regenerate SCR catalysts requires hydrocarbon addition in combination with an oxidation catalyst to raise the exhaust temperature. With the addition of an oxidation function to an SCR, ammonia (which is added as part of the SCR reaction) may also be oxidized. As a result, the SCR catalytic activity may decline and, in some cases, can potentially increase NO x emissions rather than reduce NO x emissions. Thus, catalysts have been developed specifically to oxidize ammonia.

[0007] DE10 2015 015260 A1 discloses an exhaust gas treatment system for an internal combustion engine comprising a first SCR catalyst comprising vanadium oxide, a particulate filter located downstream of the first SCR catalyst, a second SCR catalyst, i.e. a Cu-SCR, located downstream of the particulate filter and an ammonia slip catalyst located downstream of the second catalyst. The first SCR catalyst has an effect comparable to a DOC to ensure the passive regeneration of the downstream particulate filter.

[0008] DE 10 2015 016986 A1 discloses an exhaust gas treatment system for an internal combustion engine comprising at least one first catalytic converter through which the exhaust gas from the internal combustion engine can flow and at least one particle filter which is directly downstream of the catalytic converter, wherein the first catalytic converter comprises a first part which is a selective catalytic reduction (SCR) catalyst (V-SCR) and a second part downstream of the first one being an ammonia slip catalyst and a third part downstream of the second one which is an oxidation catalyst and an SCR catalyst layer disposed on the second and third part.

[0009] WO 2015 / 130216 A1 discloses an exhaust treatment system comprising an oxidation catalyst, a first dosage device arranged downstream of the oxidation, a first reduction catalyst device arranged downstream of the dosage device, a particulate filter arranged downstream of the first reduction catalyst.

[0010] US 2005 / 137079 A1 discloses a catalyst formulation including a poison adsorbing material and a catalyst material, wherein the poison adsorbing material comprises large particles and the catalytic material comprises a precious metal support and at least one of ruthenium and iridium. Said catalyst formulation is suitable for the selective reduction of NO x and the selective oxidation of hydrocarbons.

[0011] It is a known problem that close coupled selective catalytic reduction (SCR) catalysts based on copper containing zeolitic material having a framework structure of the type CHA, may be sulfated with time even though there is no upstream oxidation catalyst due to the sulfur trioxide exiting from engine and internally generated by SCR catalysts. Here, the term "close coupled" catalyst is used herein to define a catalyst which is the first catalyst receiving the exhaust gas stream exiting from an engine (the catalyst is installed close to - immediately adjacent to - the engine without any other catalytic component in between). Accordingly, it results that close coupled SCR catalysts are not able to provide sufficient DeNOx to meet the ultra-low nitrogen oxides (NOx) and nitrous oxide (N 2 O) emissions, such as CARB after sulfation.

[0012] Therefore, it was an object of the present invention to provide an exhaust gas treatment system for treating an exhaust gas stream exiting a diesel engine which is resistant to HC poisoning and prevent sulfating in order to maintain sufficient DeNOx to meet the environmental requirements, while being cost effective and avoiding engine measures such as raising exhaust gas temperatures.

[0013] Surprisingly, it was found that the exhaust gas treatment system for treating an exhaust gas stream leaving a diesel engine according to the present invention and described in the following permits to be resistant to HC poisoning and prevents sulfating in order to maintain sufficient DeNOx to meet the environmental requirements while being cost effective and by avoiding engine measures such as to raise exhaust gas temperatures.

[0014] Therefore, the present invention relates to an exhaust gas treatment system for treating an exhaust gas stream exiting a diesel engine, said exhaust gas treatment system having an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, wherein said exhaust gas treatment system comprises (i) a first catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises palladium supported on an oxidic material comprising zirconium and further comprises one or more of a vanadium oxide and a zeolitic material comprising one or more of copper and iron; (ii) a second catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises a platinum group metal supported on an oxidic material and further comprises one or more of a vanadium oxide, a tungsten oxide and a zeolitic material comprising one or more of copper and iron; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst;wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst.

[0015] Preferably, 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 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.

[0016] Preferably, the first catalyst comprises a hydrocarbon (HC) oxidation component and a nitrogen oxide (NOx) reduction component.

[0017] With respect to the oxidic material comprised in the coating of the first catalyst, it is preferred that from 90 to 100 weight-%, more preferably from 95 to 100 weight-%, more preferably from 99 to 100 weight-% of the oxidic material comprised in the coating of the first catalyst consist of zirconium and oxygen, preferably of zirconia.

[0018] It is preferred that the coating of the first catalyst according to (i) comprises a zeolitic material comprising one or more of copper and iron.

[0019] In the context of the present invention, the term "zeolitic material" refers to a zeolitic material preferably having a framework structure type ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFV, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AVL, AWO, AWW, BCT, BEA, BEC, BIK, BOF, BOG, BOZ, BPH, BRE, BSV, CAN, CAS, CDO, CFI, CGF, CGS, CHA, -CHI, -CLO, CON, CSV, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EEI, EMT, EON, EPI, ERI, ESV, ETR, EUO, *-EWT, EZT, FAR, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFO, IFR, -IFU, IFW, IFY, IHW, IMF, IRN, IRR, -IRY, ISV, ITE, ITG, ITH, *-ITN, ITR, ITT, -ITV, ITW, IWR, IWS, IWV, IWW, JBW, JNT, JOZ, JRY, JSN, JSR, JST, JSW, KFI, LAU, LEV, LIO, -LIT, LOS, LOV, LTA, LTF, LTJ, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MOZ, *MRE, MSE, MSO, MTF, MTN, MTT, MTW, MVY, MWF, MWW, NAB, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OKO, OSI, OSO, OWE, -PAR, PAU, PCR, PHI, PON, POS, PSI, PUN, RHO, -RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAF, SAO, SAS, SAT, SAV, SBE, SBN, SBS, SBT, SEW, SFE, SFF, SFG, SFH, SFN, SFO, SFS, *SFV, SFW, SGT, SIV, SOD, SOF, SOS, SSF, *-SSO, SSY, STF, STI, *STO, STT, STW, -SVR, SVV, SZR, TER, THO, TOL, TON, TSC, TUN, UEI, UFI, UOS, UOV, UOZ, USI, UTL, UWY, VET, VFI, VNI, VSV, WEI, -WEN, YUG, ZON, mixtures of two or more thereof, and mixed types of two or more thereof.

[0020] With respect to the zeolitic material comprised in the coating of the first catalyst, no specific restriction exists provided that the zeolitic material is suitable for the intended use of the first catalyst in the exhaust gas treatment system of the present invention. Preferred zeolitic materials are zeolitic materials having a framework structure of the type AEI, GME, CHA, MFI, BEA, FAU, MOR or mixtures of two or more thereof, preferably a framework structure of the type AEI, CHA, BEA or mixtures of two or more thereof. More preferably, the zeolitic material comprised in the coating of the first catalyst has a framework structure of the type CHA or AEI, more preferably a framework structure of the type CHA. Zeolitic materials having framework structure type CHA include, for example, zeolite SSZ-13 and zeolite SAPO-34 wherein SSZ-13 is preferred.

[0021] In the context of the present invention, it is preferred that the zeolitic material comprised in the coating of the first catalyst, more preferably which has a framework structure type CHA, has a mean crystallite size of at least 0.5 micrometer, preferably in the range of from 0.5 to 1.5 micrometers, more preferably in the range of from 0.6 to 1.0 micrometer, more preferably in the range of from 0.6 to 0.8 micrometer determined via scanning electron microscopy.

[0022] Preferably, the zeolitic material comprised in the coating of the first catalyst comprises copper, wherein the amount of copper comprised in the zeolitic material, calculated as CuO, is preferably in the range of from 0.1 to 10.0 weight-%, more preferably in the range of from 2.0 to 7.0 weight-%, more preferably in the range of from 2.5 to 5.5 weight-%, more preferably in the range of from 2.5 to 3.5 weight-%, based on the total weight of the zeolitic material. More preferably, the amount of iron comprised in the zeolitic material, calculated as Fe 2 O 3 , is in the range of from 0 to 0.01 weight-%, more preferably in the range of from 0 to 0.001 weight-%, more preferably in the range of from 0 to 0.0001 weight-%, based on the total weight of the zeolitic material.

[0023] Preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the framework structure of the zeolitic material consist to Si, Al, O, and optionally one or more of H and P, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO 2 : Al 2 O 3 , is preferably in the range of from 2:1 to 50:1, more preferably in the range of from 4:1 to 45:1, more preferably in the range of from 10:1 to 40: 1, more preferably in the range of from 20: 1 to 35: 1.

[0024] Preferably, the zeolitic material comprised in the coating of the first catalyst comprises iron, wherein the amount of iron comprised in the zeolitic material, calculated as Fe 2 O 3 , is preferably in the range of from 0.1 to 10.0 weight-%, more preferably in the range of from 1.0 to 7.0 weight-%, more preferably in the range of from 2.5 to 5.5 weight-% based on the total weight of the zeolitic material. More preferably, from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the framework structure of the zeolitic material consist to Si, Al, O, and optionally one or more of H and P, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO 2 : Al 2 O 3 , is preferably in the range of from 2:1 to 50:1, more preferably in the range of from 4:1 to 45:1, more preferably in the range of from 10:1 to 40: 1, more preferably in the range of from 20: 1 to 35: 1.

[0025] Preferably, the coating of the first catalyst further comprises a metal oxide binder, wherein the metal oxide binder preferably comprises one or more of zirconia, alumina, titania, silica, and a mixed oxide comprising two or more of Zr, Al, Ti, and Si, more preferably comprises one or more of alumina and zirconia, more preferably comprises zirconia. More preferably, the coating of the first catalyst comprises the metal oxide binder at a loading in the range of from 1.22 to 12.20 g / l (0.02 to 0.2 g / in 3< ), more preferably in the range of from 4.27 to 9.15 g / l (0.07 to 0.15 g / in 3< ).

[0026] According to the present invention, it is preferred that the coating of the first catalyst according to (i) comprises a vanadium oxide, wherein the vanadium oxide is preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide. Optionally, the vanadium oxide contains one or more of tungsten, iron and antimony.

[0027] Preferably, the vanadium oxide is supported on an oxidic material comprising one or more of titanium, silicon and zirconium, preferably an oxidic material comprising one or more of titanium and silicon, more preferably an oxidic material comprising one or more of titania and silica, more preferably on titania, wherein titania optionally contains one or more of tungsten and silicon. With regard to the substrate of the first catalyst according to (i), it is preferred that said substrate comprises, preferably consists of, a ceramic or metallic substance.

[0028] With regard to the substrate of the first catalyst comprising, preferably consisting of, a ceramic substrate, no specific restriction exists provided that the substrate is suitable for the intended use of the first catalyst comprised in the exhaust gas treatment system of the present invention. It is preferred that the ceramic substance comprises, more preferably consists of, one or more of an alumina, a silica, a silicate, an aluminosilicate, preferably a cordierite or a mullite, an aluminotitanate, a silicon carbide, a zirconia, a magnesia, preferably a spinel, and a titania, more preferably one or more of a silicon carbide and a cordierite, more preferably a cordierite.

[0029] With regard to the substrate of the first catalyst comprising, preferably consisting of, a metallic substrate, no specific restriction exists provided that the substrate is suitable for the intended use of the first catalyst comprised in the exhaust gas treatment system of the present invention. It is preferred that the metallic substance comprises, more preferably consists of, oxygen and one or more of iron, chromium, and aluminum.

[0030] It is preferred that the substrate of the first catalyst according to (i) is a monolith, preferably a honeycomb monolith, more preferably a flow-through honeycomb monolith.

[0031] According to the present invention, it is preferred that the substrate of the first catalyst has a substrate length and the coating of the first catalyst is disposed on 20 to 100 %, preferably on 50 to 100 %, more preferably on 75 to 100 %, more preferably on 95 to 100 %, more preferably on 99 to 100 % of the substrate length.

[0032] Generally, there is no restriction regarding the loading of palladium comprised in the coating of the first catalyst provided that the palladium loading is suitable for the intended use in the first catalyst in the exhaust gas treatment system. Preferably, the coating of the first catalyst comprises palladium at a loading in the range of from 0.035 to 2.82 g / l (1 to 80 g / ft 3< ), more preferably in the range of from 0.53 to 2.12 g / l (15 to 60 g / ft 3< ), more preferably in the range of from 0.71 to 1.77 g / l (20 to 50 g / ft 3< ), more preferably in the range of from 0.88 to 1.59 g / l (25 to 45 g / ft 3< ), more preferably in the range of from 0.88 to 1.24 g / l (25 to 35 g / ft 3< ).

[0033] As for the palladium loading, there is generally no restriction regarding the loading of the zeolitic material comprised in the coating of the first catalyst provided that the loading of the zeolitic material is suitable for the intended use in the first catalyst in the exhaust gas treatment system. Preferably, the coating of the first catalyst comprises the zeolitic material at a loading in the range of from 61.02 to 274.61 g / l (1.0 to 4.5 g / in 3< ), more preferably in the range of from 91.54 to 244.10 g / l (1.5 to 4.0 g / in 3< ), more preferably in the range of from 122.05 to 183.07 g / l (2.0 to 3.0 g / in 3< ), more preferably in the range of from 128.15 to 170.87 g / l (2.1 to 2.8 g / in 3< ), more preferably in the range of from 128.15 to 158.66 g / l (2.1 to 2.6 g / in 3< ).

[0034] Generally, there is no restriction regarding the loading of the vanadium oxide comprised in the coating of the first catalyst provided that the loading of the vanadium oxide is suitable for the intended use in the first catalyst in the exhaust gas treatment system. Preferably, the coating of the first catalyst comprises the vanadium oxide at a loading in the range of from 122.04 to 366.14 g / l (2.0 to 6.0g / in 3< ), more preferably in the range of from 183.07 to 335.63 g / l (3.0 to 5.5 g / in 3< ), more preferably in the range of from 244.1 to 305.12 g / l (4.0 to 5.0 g / in 3< ).

[0035] According to the present invention, 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 coating of the first catalyst comprise, preferably consist of, palladium supported on an oxidic material wherein from 99 to 100 weight-% of said oxidic material consist of zirconium and oxygen, preferably of zirconia, a copper containing zeolitic material having a framework structure of the type CHA, and preferably a metal oxide binder as defined in the present invention.

[0036] Therefore, the present invention preferably relates to an exhaust gas treatment system for treating an exhaust gas stream exiting a diesel engine, said exhaust gas treatment system having an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, wherein said exhaust gas treatment system comprises (i) a first catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises palladium supported on an oxidic material comprising zirconium and further comprises a zeolitic material comprising one or more of copper and iron, 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 coating of the first catalyst comprise, preferably consist of, palladium supported on an oxidic material wherein from 99 to 100 weight-% of said oxidic material consist of zirconium and oxygen, preferably of zirconia, a copper containing zeolitic material having a framework structure of the type CHA, and preferably a metal oxide binder as defined in the present invention; (ii) a second catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises a platinum group metal supported on an oxidic material and further comprises one or more of a vanadium oxide, a tungsten oxide and a zeolitic material comprising one or more of copper and iron; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst; wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst.

[0037] According to the present invention, 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 coating of the first catalyst comprise, preferably consist of, palladium supported on an oxidic material wherein from 99 to 100 weight-% of said oxidic material consist of zirconium and oxygen, preferably of zirconia, and a vanadium oxide supported on titania, wherein titania optionally contains one or more of tungsten and silicon.

[0038] Therefore, the present invention preferably relates to an exhaust gas treatment system for treating an exhaust gas stream exiting a diesel engine, said exhaust gas treatment system having an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, wherein said exhaust gas treatment system comprises (i) a first catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises palladium supported on an oxidic material comprising zirconium and further comprises a vanadium oxide 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 coating of the first catalyst comprise, preferably consist of, palladium supported on an oxidic material wherein from 99 to 100 weight-% of said oxidic material consist of zirconium and oxygen, preferably of zirconia, and a vanadium oxide supported on titania, wherein titania optionally contains one or more of tungsten and silicon; (ii) a second catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises a platinum group metal supported on an oxidic material and further comprises one or more of a vanadium oxide, a tungsten oxide and a zeolitic material comprising one or more of copper and iron; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst; wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst.

[0039] According to the present invention, it is preferred that the first catalyst according to (i) has a selective catalytic reduction (SCR) component and a diesel oxidation component.

[0040] Preferably from 0 to 0.0035 g / l, more preferably from 0 to 0.00035 g / l, more preferably from 0 to 0.000035 g / l of one or more of platinum, iridium, osmium and rhodium are comprised in the coating of the first catalyst, wherein more preferably, from 0 to 0.000035 g / l of platinum, iridium, osmium and rhodium are comprised in the coating of the first catalyst.

[0041] Preferably, the coating of the first catalyst is free of platinum, more preferably free of platinum and rhodium, more preferably free of platinum, rhodium, iridium and osmium.

[0042] Preferably from 0 to 2 weight-%, more preferably from 0 to 1 weight-%, more preferably from 0 to 0.1 weight-% of the oxidic material supporting palladium comprised in the coating of the first catalyst consist of ceria and alumina, wherein more preferably from 0 to 0.1 weight-% of the oxidic material comprised in the coating of the first catalyst consists of ceria, alumina, titania, lanthana and baria.

[0043] Preferably, the oxidic material supporting palladium comprised in the coating of the first catalyst is free of ceria and alumina, more preferably free of ceria, alumina and titania, more preferably free of ceria, alumina, titania, lanthana and baria.

[0044] According to the present invention, it is preferred that the second catalyst according to (ii) comprises a nitrogen oxide (NOx) reduction component and an ammonia oxidation component.

[0045] It is preferred that the second catalyst according to (ii) is an ammonia oxidation (AMOX) catalyst.

[0046] Preferably, the coating of the second catalyst according to (ii) comprises a zeolitic material comprising one or more of copper and iron.

[0047] With respect to the zeolitic material comprised in the coating of the second catalyst, no specific restriction exists provided that said zeolitic material is suitable for the intended use of the second catalyst in the exhaust gas treatment system of the present invention. Generally, the zeolitic material comprised in the coating of the second catalyst nay have a framework structure of the type ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFV, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AVL, AWO, AWW, BCT, BEA, BEC, BIK, BOF, BOG, BOZ, BPH, BRE, BSV, CAN, CAS, CDO, CFI, CGF, CGS, CHA, -CHI, - CLO, CON, CSV, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EEI, EMT, EON, EPI, ERI, ESV, ETR, EUO, *-EWT, EZT, FAR, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFO, IFR, -IFU, IFW, IFY, IHW, IMF, IRN, IRR, -IRY, ISV, ITE, ITG, ITH, *-ITN, ITR, ITT, -ITV, ITW, IWR, IWS, IWV, IWW, JBW, JNT, JOZ, JRY, JSN, JSR, JST, JSW, KFI, LAU, LEV, LIO, - LIT, LOS, LOV, LTA, LTF, LTJ, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MOZ, *MRE, MSE, MSO, MTF, MTN, MTT, MTW, MVY, MWF, MWW, NAB, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OKO, OSI, OSO, OWE, -PAR, PAU, PCR, PHI, PON, POS, PSI, PUN, RHO, -RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAF, SAO, SAS, SAT, SAV, SBE, SBN, SBS, SBT, SEW, SFE, SFF, SFG, SFH, SFN, SFO, SFS, *SFV, SFW, SGT, SIV, SOD, SOF, SOS, SSF, *-SSO, SSY, STF, STI, *STO, STT, STW, -SVR, SVV, SZR, TER, THO, TOL, TON, TSC, TUN, UEI, UFI, UOS, UOV, UOZ, USI, UTL, UWY, VET, VFI, VNI, VSV, WEI, -WEN, YUG, ZON, mixtures of two or more thereof, and mixed types of two or more thereof. Preferably, the zeolitic material comprised in the coating of the second catalyst has a framework structure of the type AEI, GME, CHA, MFI, BEA, FAU, MOR or mixtures of two or more thereof, more preferably a framework structure of the type AEI, CHA, BEA or mixtures of two or more thereof, more preferably a framework structure of the type CHA or AEI, more preferably a framework structure of the type CHA. Zeolitic materials having framework structure type CHA include, for example, zeolite SSZ-13 and zeolite SAPO-34 wherein SSZ-13 is preferred.

[0048] In the context of the present invention, it is preferred that the zeolitic material comprised in the coating of the second catalyst, more preferably which has a framework structure type CHA, has a mean crystallite size of at least 0.5 micrometer, preferably in the range of from 0.5 to 1.5 micrometers, more preferably in the range of from 0.6 to 1.0 micrometer, more preferably in the range of from 0.6 to 0.8 micrometer determined via scanning electron microscopy.

[0049] Preferably, the zeolitic material comprised in the coating of the second catalyst comprises copper, wherein the amount of copper comprised in the zeolitic material, calculated as CuO, is preferably in the range of from 0.1 to 10.0 weight-%, more preferably in the range of from 2.0 to 7.0 weight-%, more preferably in the range of from 2.5 to 5.5 weight-%, more preferably in the range of from 2.5 to 3.5 weight-%, based on the total weight of the zeolitic material. More preferably, the amount of iron comprised in the zeolitic material, calculated as Fe 2 O 3 , is in the range of from 0 to 0.01 weight-%, more preferably in the range of from 0 to 0.001 weight-%, more preferably in the range of from 0 to 0.0001 weight-%, based on the total weight of the zeolitic material.

[0050] Preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the framework structure of the zeolitic material consist to Si, Al, O, and optionally one or more of H and P, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO 2 : Al 2 O 3 , is preferably in the range of from 2:1 to 50:1, more preferably in the range of from 4:1 to 40:1, more preferably in the range of from 10:1 to 40: 1, more preferably in the range of from 20: 1 to 35: 1.

[0051] Preferably, 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 Fe 2 O 3 , is preferably in the range of from 0.1 to 10.0 weight-%, more preferably in the range of from 1.0 to 7.0 weight-%, more preferably in the range of from 2.5 to 5.5 weight-%, based on the total weight of the zeolitic material. More preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the framework structure of the zeolitic material consist to Si, Al, O, and optionally one or more of H and P, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO 2 : Al 2 O 3 , is preferably in the range of from 2:1 to 50:1, more preferably in the range of from 4:1 to 40:1, more preferably in the range of from 10:1 to 40:1, more preferably in the range of from 20:1 to 35:1.

[0052] Preferably, the coating of the second catalyst further comprises a metal oxide binder, wherein the metal oxide binder preferably comprises one or more of zirconia, alumina, titania, silica, and a mixed oxide comprising two or more of Zr, Al, Ti, and Si, more preferably comprises one or more of alumina and zirconia, more preferably comprises zirconia. More preferably, the coating of the second catalyst comprises the metal oxide binder at a loading in the range of from 1.22 to 12.20 g / l (0.02 to 0.2 g / in 3< ), more preferably in the range of from 4.27 to 9.15 g / l (0.07 to 0.15 g / in 3< ).

[0053] It is preferred that the platinum group metal comprised in the coating of the second catalyst is one or more of platinum, palladium and rhodium, preferably one or more of platinum and palladium.

[0054] Preferably, the platinum group metal comprised in the coating of the second catalyst is a mixture of platinum and palladium. More preferably, the weight ratio of platinum: palladium, calculated as elemental platinum and elemental palladium, comprised in the coating of the second catalyst, is in the range of from 1:1 to 30:1, more preferably in the range of from 5:1 to 20:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1.

[0055] Alternatively, the platinum group metal comprised in the coating of the second catalyst is platinum.

[0056] According to the present invention, it is preferred that the oxidic material supporting the platinum group metal comprised in the coating of the second catalyst comprises, preferably consists of, one or more of alumina, zirconia, silica, titania and ceria, preferably one or more of alumina, silica and zirconia, more preferably one or more of zirconia and alumina.

[0057] Preferably from 20 to 100 weight-%, more preferably from 40 to 100 weight-%, more preferably from 60 to 100 weight-%, more preferably from 70 to 90 weight-%, more preferably from 75 to 85 weight-% of the oxidic material supporting the platinum group metal comprised in the coating of the second catalyst consist of alumina.

[0058] According to the present invention, it is preferred that the coating of the second catalyst according to (ii) comprises a vanadium oxide, wherein the vanadium oxide is preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide. Optionally, the vanadium oxide contains one or more of tungsten, iron and antimony.

[0059] Preferably, the vanadium oxide is supported on an oxidic material comprising one or more of titanium, silicon and zirconium, more preferably an oxidic material comprising one or more of titanium and silicon, more preferably an oxidic material comprising one or more of titania and silica, more preferably on titania, wherein titania optionally contains one or more of tungsten and silicon.

[0060] It is preferred that the coating of the second catalyst comprises a tungsten oxide, wherein the tungsten oxide is preferably a tungsten trioxide, wherein the tungsten oxide optionally contains one or more of iron and antimony. Preferably, the tungsten oxide is supported on an oxidic material comprising one or more of titanium and zirconium, more preferably an oxidic material comprising one or more of titania and zirconia, more preferably on titania.

[0061] It is preferred that the coating of the second catalyst comprises a vanadium oxide and a tungsten oxide, wherein the tungsten oxide is a tungsten trioxide, wherein the vanadium oxide is preferably supported on an oxidic material comprising one or more of titanium, silicon and zirconium, preferably an oxidic material comprising one or more of titanium and silicon, more preferably an oxidic material comprising one or more of titania and zirconia, more preferably on titania, wherein titania optionally contains one or more of tungsten and silicon, and the tungsten oxide is preferably supported on an oxidic material comprising one or more of titanium and zirconium, more preferably an oxidic material comprising one or more of titania and zirconia, more preferably on titania.

[0062] With respect to the substrate of the second catalyst, it is preferred that said substrate comprises, more preferably consists of, a ceramic or metallic substance.

[0063] With regard to the substrate of the second catalyst comprising, preferably consisting of, a ceramic substrate, no specific restriction exists provided that the substrate is suitable for the intended use of the second catalyst comprised in the exhaust gas treatment system of the present invention. It is preferred that the ceramic substance preferably comprises, more preferably consists of, one or more of an alumina, a silica, a silicate, an aluminosilicate, preferably a cordierite or a mullite, an aluminotitanate, a silicon carbide, a zirconia, a magnesia, preferably a spinel, and a titania, more preferably one or more of a silicon carbide and a cordierite, more preferably a cordierite.

[0064] With regard to the substrate of the second catalyst comprising, preferably consisting of, a metallic substrate, no specific restriction exists provided that the substrate is suitable for the intended use of the second catalyst comprised in the exhaust gas treatment system of the present invention. It is preferred that the metallic substance preferably comprises, more preferably consists of, oxygen and one or more of iron, chromium, and aluminum.

[0065] It is preferred that the substrate of the second catalyst is a monolith, preferably a honeycomb monolith, more preferably a flow-through honeycomb monolith.

[0066] Preferably, the substrate of the second catalyst has a substrate length and the coating of the second catalyst is disposed on 20 to 100 %, preferably on 50 to 100 %, more preferably on 75 to 100 %, more preferably on 95 to 100 %, more preferably on 99 to 100 % of the substrate length.

[0067] Generally, there is no specific restriction regarding the loading of the platinum group metal comprised in the coating of the second catalyst provided that said loading is suitable for the intended use of the second catalyst in the exhaust gas treatment system of the present invention. Preferably, the platinum group metal, calculated as elemental platinum group metal, at a loading in the range of from 0.035 to 0.53 g / l (1 to 15 g / ft 3< ), more preferably in the range of from 0.11 to 0.35 g / l (3 to 10 g / ft 3< ), more preferably in the range of from 0.16 to 0.32 g / l (4.5 to 9.0 g / ft 3< ), more preferably in the range of from 0.26 to 0.30 g / l (7.5 to 8.5 g / ft 3< ).

[0068] Generally, there is no specific restriction regarding the loading of the zeolitic material comprised in the coating of the second catalyst provided that said loading is suitable for the intended use of the second catalyst in the exhaust gas treatment system of the present invention. Preferably, the coating of the second catalyst comprises the zeolitic material at a loading in the range of from 30.51 to 335.63 g / l (0.5 to 5.5 g / in 3< ), more preferably in the range of from 91.54 to 305.12 g / l (1.5 to 5.0 g / in 3< ), more preferably in the range of from 122.05 to 244.09 g / l (2.0 to 4.0 g / in 3< ), more preferably in the range of from 122.05 to 213.58 g / l (2.0 to 3.5 g / in 3< ).

[0069] According to the present invention, no specific restriction exists regarding the loading of the vanadium oxide comprised in the coating of the second catalyst provided that said loading is suitable for the intended use of the second catalyst in the exhaust gas treatment system of the present invention. Preferably, the coating of the second catalyst comprises one or more of a vanadium oxide and a tungsten oxide at a loading in the range of from 122.04 to 366.14 g / l (2.0 to 6.0 g / in 3< ), more preferably in the range of from 183.07 to 335.63 g / l (3.0 to 5.5 g / in 3< ), more preferably in the range of from 244.1 to 305.12 g / l (4.0 to 5.0g / in 3< ).

[0070] According to the present invention, it is preferred that the coating of the second catalyst comprises, preferably consists of, a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt: Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention. More preferably, 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 coating of the second catalyst comprise a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt: Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention.

[0071] According to the present invention, the coating of the first catalyst comprises, preferably consists of, palladium supported on an oxidic material comprising zirconium, preferably consisting of zirconium and oxygen, more preferably zirconia, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention; and the coating of the second catalyst comprises, preferably consists of, a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt: Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention.

[0072] Therefore, the present invention preferably relates to an exhaust gas treatment system for treating an exhaust gas stream exiting a diesel engine, said exhaust gas treatment system having an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, wherein said exhaust gas treatment system comprises (i) a first catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises, preferably consists of, palladium supported on an oxidic material comprising zirconium, preferably consisting of zirconium and oxygen, more preferably zirconia, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention; (ii) a second catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises, preferably consists of, a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt: Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst; wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst.

[0073] More preferably 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 coating of the first catalyst comprises palladium supported on an oxidic material consisting of zirconia, a zeolitic material having a framework structure type CHA comprising copper, and preferably a metal oxide binder as defined in the present invention; and 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 coating of the second catalyst comprises a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt: Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention.

[0074] Alternatively, it is preferred that the coating of the first catalyst comprises, preferably consists of, palladium supported on an oxidic material comprising zirconium, preferably consisting of zirconium and oxygen, more preferably zirconia, and a vanadium oxide supported on titania, wherein the vanadium oxide is more preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony, wherein titania optionally contains one or more of tungsten and silicon; and that the coating of the second catalyst comprises, preferably consists of, a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt: Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention.

[0075] Therefore, the present invention preferably relates to an exhaust gas treatment system for treating an exhaust gas stream exiting a diesel engine, said exhaust gas treatment system having an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, wherein said exhaust gas treatment system comprises (i) a first catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises, preferably consists of, palladium supported on an oxidic material comprising zirconium, preferably consisting of zirconium and oxygen, more preferably zirconia, and a vanadium oxide supported on titania, wherein the vanadium oxide is more preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony, wherein titania optionally contains one or more of tungsten and silicon; (ii) a second catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises, preferably consists of, a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt: Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst; wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst.

[0076] More preferably 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 coating of the first catalyst comprises, preferably consists of, palladium supported on an oxidic material consisting of zirconia and a vanadium oxide supported on titania, wherein the vanadium oxide is more preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony, wherein titania optionally contains one or more of tungsten and silicon; and 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 coating of the second catalyst comprises a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt:Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention.

[0077] Alternatively, it is preferred that the coating of the second catalyst comprises, preferably consists of, platinum supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention. More preferably, 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 coating of the second catalyst comprise platinum supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention.

[0078] According to the present invention, it is preferred that the coating of the first catalyst comprises, preferably consists of, palladium supported on an oxidic material comprising zirconium, preferably consisting of zirconia, and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention; and that the coating of the second catalyst comprises, preferably consists of, platinum supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention.

[0079] Therefore, the present invention preferably relates to an exhaust gas treatment system for treating an exhaust gas stream exiting a diesel engine, said exhaust gas treatment system having an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, wherein said exhaust gas treatment system comprises (i) a first catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises, preferably consists of, palladium supported on an oxidic material comprising zirconium, preferably consisting of zirconium and oxygen, more preferably zirconia, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention; (ii) a second catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises, preferably consists of, platinum supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst; wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst.

[0080] More preferably 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 coating of the first catalyst comprises palladium supported on an oxidic material consisting of zirconia and a zeolitic material having a framework structure type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention; and 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 coating of the second catalyst comprises platinum supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention.

[0081] Alternatively, it is preferred that the coating of the first catalyst comprises, preferably consists of, palladium supported on an oxidic material comprising zirconium, preferably consisting of zirconium and oxygen, more preferably zirconia, and a vanadium oxide supported on titania, wherein the vanadium oxide is more preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony, wherein titania optionally contains tungsten and silicon; and that the coating of the second catalyst comprises, preferably consists of, platinum supported on an oxidic material comprising a mixture of zirconia and alumina and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention.

[0082] Therefore, the present invention further relates to an exhaust gas treatment system for treating an exhaust gas stream exiting a diesel engine, said exhaust gas treatment system having an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, wherein said exhaust gas treatment system comprises (i) a first catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises, preferably consists of, palladium supported on an oxidic material comprising zirconium, preferably consisting of zirconium and oxygen, more preferably zirconia, and a vanadium oxide supported on titania, wherein the vanadium oxide is more preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony, wherein titania optionally contains tungsten and silicon; (ii) a second catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises, preferably consists of, platinum supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst; wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst.

[0083] More preferably 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 coating of the first catalyst comprises palladium supported on an oxidic material consisting of zirconia and a vanadium oxide supported on titania, wherein the vanadium oxide is more preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony; and 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 coating of the second catalyst comprises platinum supported on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in the present invention.

[0084] According to the present invention, it is preferred that the substrate of the first catalyst comprises, preferably consists of, a cordierite and the substrate of the second catalyst comprises, preferably consists of, a cordierite.

[0085] Preferably, the substrate of the first catalyst on which substrate the coating of the first catalyst is disposed, is a first substrate and the substrate of the second catalyst on which substrate the coating of the second catalyst is disposed, is a second substrate, wherein the first substrate and the second substrate are different from each other.

[0086] With respect to the size (length and width) of the substrates of the first catalyst and of the second catalyst, no specific restriction exists provided that each substrate is suitable for the intended used of the first catalyst and of the second catalyst, respectively, comprised in the exhaust gas treatment system of the present invention.

[0087] Preferably, the substrate of the first catalyst has a substrate length in the range of from 2.54 to 25.4 cm (1 to 10 inches), preferably in the range of from 5.08 to 20.32 cm (2 to 8 inches), more preferably in the range of from 10.16 to 19.05 cm (4 to 7.5 inches), more preferably in the range of from 12.7 to 17.78 cm (5 to 7 inches).

[0088] Preferably, the substrate of the second catalyst has a substrate length in the range of from 2.54 to 25.4 cm (1 to 10 inches), more preferably in the range of from 3.81 to 17.78 cm (1.5 to 7 inches), more preferably in the range of from 5.08 to 12.7 cm (2 to 5 inches), more preferably in the range of from 5.08 to 10.16 cm (2 to 4 inches). More preferably, the substrate of the first catalyst has a substrate length in the range of from12.7 to 17.78 cm (5 to 7 inches) and the substrate of the second catalyst has a substrate length in the range of from 5.08 to 10.16 cm (2 to 4 inches).

[0089] Preferably, the length of the first substrate is greater than the length of the second substrate, wherein the ratio of the length of the first substrate relative to the length of the second substrate is preferably in the range of from 1.1:1 to 4:1, more preferably in the range of from 1.5:1 to 3.5:1, more preferably in the range of from 1.9:1 to 2.1:1.

[0090] Preferably, the substrate of the first catalyst has a substrate width in the range of from 10.16 to 43.18 cm (4 to 17 inches), preferably in the range of from 17.78 to 38.10 cm (7 to 15 inches), more preferably in the range of from 20.32 to 35.56 cm (8 to 14 inches), more preferably in the range of from 22.86 to 33.02 cm (9 to 13 inches), more preferably in the range of from 22.86 to 27.94 cm (9 to 11 inches).

[0091] Preferably, the substrate of the second catalyst has a substrate width in the range of from 10.16 to 43.18 cm (4 to 17 inches), more preferably in the range of from 17.78 to 38.10 cm (7 to 15 inches), more preferably in the range of from 20.32 to 35.56 cm (8 to 14 inches), more preferably in the range of from 22.86 to 33.02 cm (9 to 13 inches), more preferably in the range of from 22.86 to 27.94 cm (9 to 11 inches). More preferably, the substrate of the first catalyst has a substrate width in the range of from 22.86 to 33.02 cm (9 to 13 inches), more preferably in the range of from 22.86 to 27.94 cm (9 to 11 inches) and the substrate of the second catalyst has a substrate width in the range of from 22.86 to 33.02 cm (9 to 13 inches), more preferably in the range of from 22.86 to 27.94 cm (9 to 11 inches).

[0092] According to the present invention, it may be preferred that the substrate of the first catalyst, on which substrate the coating of the first catalyst is disposed, and the substrate of the second catalyst, on which substrate the coating of the second catalyst is disposed, together form a single substrate, wherein said single substrate comprises an inlet end and an outlet end, wherein the inlet end is arranged upstream of the outlet end, and the coating of the first catalyst is disposed on said single substrate from the inlet end towards the outlet end of said single substrate and the coating of the second catalyst is disposed on said single substrate from the outlet end towards the inlet end of said single substrate, wherein the coating of the first catalyst covers from 25 to 75 % of the substrate length and the coating of the second catalyst covers from 25 to 75 % of the substrate length. More preferably, the coating of the first catalyst covers from 25 to 70 %, preferably from 35 to 65 %, more preferably from 45 to 55 %, of the substrate length and the coating of the second catalyst covers from 25 to 70 %, preferably from 35 to 65 %, more preferably on from 45 to 55 % of the substrate length. Alternatively, more preferably, the coating of the first catalyst covers from 50 to 75 %, preferably from 69 to 75 % of the substrate length and the coating of the second catalyst covers from 25 to 50 %, preferably from 25 to 31 % of the substrate length.

[0093] Preferably, the coating of the first catalyst and the coating of the second catalyst overlap. As an alternative, it is preferred that there is a gap between the coating of the first catalyst and the coating of the second catalyst.

[0094] According to the present invention, the first catalyst preferably comprises no further coating. Preferably, the first catalyst consists of a coating disposed on a substrate.

[0095] According to the present invention, it is preferred that the second catalyst comprises no further coating. Preferably, the second catalyst consists of a coating disposed on a substrate.

[0096] More preferably, the first catalyst consists of a coating disposed on a substrate and the second catalyst consists of a coating disposed on a substrate.

[0097] According to the present invention, it is preferred that the exhaust gas treatment system further comprises an injector for injecting a fluid into the exhaust gas stream exiting the diesel engine, said injector being located upstream of the first catalyst and downstream of the upstream end of the exhaust gas treatment system. More preferably, the fluid is a urea solution, more preferably an aqueous urea solution.

[0098] According to the present invention, it is preferred that the exhaust gas treatment system further comprises one or more of a diesel oxidation catalyst, a nitrogen oxides reduction catalyst and an ammonia oxidation catalyst located downstream of the second catalyst according to (ii).

[0099] Preferably, the exhaust gas treatment system further comprises a diesel oxidation catalyst and a particulate filter, preferably a catalyzed particulate filter, wherein the diesel oxidation catalyst has an inlet end and an outlet end and is located downstream of the second catalyst according to (ii) and the particulate filter is located downstream of the diesel oxidation catalyst towards the downstream end of the exhaust gas treatment system. More preferably, the outlet end of the second catalyst according to (ii) is in fluid communication with the inlet end of the diesel oxidation catalyst and between the outlet end of the second catalyst according to (li) and the inlet end of the diesel oxidation catalyst, no catalyst for treating the exhaust gas stream exiting the second catalyst is located in the exhaust gas treatment system.

[0100] Alternatively, it is preferred that the exhaust gas treatment system further comprises a particulate filter, wherein the particulate filter has an inlet end and an outlet end and is located downstream of the second catalyst according to (ii), preferably wherein the outlet end of the second catalyst according to (ii) is in fluid communication with the inlet end of the particulate filter and between the outlet end of the second catalyst according to (ii) and the inlet end of the particulate filter, no catalyst for treating the exhaust gas stream exiting the second catalyst is located in the exhaust gas treatment system. More preferably, the particulate filter is a catalyzed particulate filter.

[0101] 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 (1) providing an exhaust gas stream from a diesel engine comprising one or more of NOx, ammonia, nitrogen monoxide and a hydrocarbon; (2) passing the exhaust gas stream provided in (1) through the exhaust gas system according to the present invention.

[0102] The present invention is illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. Further, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as "The exhaust gas treatment system of any one of embodiments 1 to 4", every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to "The exhaust gas treatment system of any one of embodiments 1, 2, 3 and 4". 1. An exhaust gas treatment system for treating an exhaust gas stream exiting a diesel engine, said exhaust gas treatment system having an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, wherein said exhaust gas treatment system comprises (i) a first catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises palladium supported on an oxidic material comprising zirconium and further comprises one or more of a vanadium oxide and a zeolitic material comprising one or more of copper and iron; (ii) a second catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises a platinum group metal supported on an oxidic material and further comprises one or more of a vanadium oxide, a tungsten oxide and a zeolitic material comprising one or more of copper and iron; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst; wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst. 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. 3. The exhaust gas treatment system of embodiment 1 or 2, wherein the first catalyst comprises a hydrocarbon (HC) oxidation component and a nitrogen oxide (NOx) reduction component. 4. The exhaust gas treatment system of any one of embodiments 1 to 3, wherein from 90 to 100 weight-%, preferably from 95 to 100 weight-%, more preferably from 99 to 100 weight-% of the oxidic material comprised in the coating of the first catalyst consist of zirconium and oxygen, preferably of zirconia. 5. The exhaust gas treatment system of any one of embodiments 1 to 4, wherein the coating of the first catalyst according to (i) comprises a zeolitic material comprising one or more of copper and iron. 6. The exhaust gas treatment system of any one of embodiments 1 to 5, wherein the zeolitic material comprised in the coating of the first catalyst has a framework structure of the type AEI, GME, CHA, MFI, BEA, FAU, MOR or mixtures of two or more thereof, preferably a framework structure of the type AEI, CHA, BEA or mixtures of two or more thereof, more preferably a framework structure of the type CHA or AEI, more preferably a framework structure of the type CHA. 7. The exhaust gas treatment system of any one of embodiments 1 to 6, wherein the zeolitic material comprised in the coating of the first catalyst, preferably which has a framework type CHA, has a mean crystallite size of at least 0.5 micrometer, preferably in the range of from 0.5 to 1.5 micrometers, more preferably in the range of from 0.6 to 1.0 micrometer, more preferably in the range of from 0.6 to 0.8 micrometer determined via scanning electron microscopy. 8. The exhaust gas treatment system of any one of embodiment 5 to 7, wherein the zeolitic material comprised in the coating of the first catalyst comprises copper, wherein the amount of copper comprised in the zeolitic material, calculated as CuO, is preferably in the range of from 0.1 to 10.0 weight-%, more preferably in the range of from 2.0 to 7.0 weight-%, more preferably in the range of from 2.5 to 5.5 weight-%, more preferably in the range of from 2.5 to 3.5 weight-%, based on the total weight of the zeolitic material, wherein the amount of iron comprised in the zeolitic material, calculated as Fe 2 O 3 , is more preferably in the range of from 0 to 0.01 weight-%, more preferably in the range of from 0 to 0.001 weight-%, more preferably in the range of from 0 to 0.0001 weight-%, based on the total weight of the zeolitic material. 9. The exhaust gas treatment system of embodiment 7 or 8, wherein from 95 to 100 weight-%, preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the framework structure of the zeolitic material consist to Si, Al, O, and optionally one or more of H and P, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO 2 : Al 2 O 3 , is preferably in the range of from 2:1 to 50:1, more preferably in the range of from 4:1 to 45:1, more preferably in the range of from 10:1 to 40: 1, more preferably in the range of from 20: 1 to 35: 1. 10. The exhaust gas treatment system of any one of embodiments 1 to 6, wherein the zeolitic material comprised in the coating of the first catalyst comprises iron, wherein the amount of iron comprised in the zeolitic material, calculated as Fe 2 O 3 , is preferably in the range of from 0.1 to 10.0 weight-%, more preferably in the range of from 1.0 to 7.0 weight-%, more preferably in the range of from 2.5 to 5.5 weight-% based on the total weight of the zeolitic material, and wherein preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the framework structure of the zeolitic material consist to Si, Al, O, and optionally one or more of H and P, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO 2 : Al 2 O 3 , is preferably in the range of from 2:1 to 50:1, more preferably in the range of from 4:1 to 45:1, more preferably in the range of from 10:1 to 40: 1, more preferably in the range of from 20: 1 to 35: 1. 11. The exhaust gas treatment system of any one of embodiments 1 to 10, wherein the coating of the first catalyst further comprises a metal oxide binder, wherein the metal oxide binder preferably comprises one or more of zirconia, alumina, titania, silica, and a mixed oxide comprising two or more of Zr, Al, Ti, and Si, more preferably comprises one or more of alumina and zirconia, more preferably comprises zirconia; wherein the coating of the first catalyst more preferably comprises the metal oxide binder at a loading in the range of from 1.22 to 12.20 g / l (0.02 to 0.2 g / in 3< ), more preferably in the range of from 4.27 to 9.15 g / l (0.07 to 0.15 g / in 3< ). 12. The exhaust gas treatment system of any one of embodiments 1 to 11, wherein the coating of the first catalyst according to (i) comprises a vanadium oxide, wherein the vanadium oxide is preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony. 13. The exhaust gas treatment system of embodiment 12, wherein the vanadium oxide is supported on an oxidic material comprising one or more of titanium, silicon and zirconium, preferably an oxidic material comprising one or more of titanium and silicon, more preferably an oxidic material comprising one or more of titania and silica, more preferably on titania, wherein titania optionally contains one or more of tungsten and silicon. 14. The exhaust gas treatment system of any one of embodiments 1 to 13, wherein the substrate of the first catalyst comprises a ceramic or metallic substance. 15. The exhaust gas treatment system of any one of embodiments 1 to 14, wherein the substrate of the first catalyst comprises, preferably consists of, a ceramic substance, wherein the ceramic substance preferably comprises, more preferably consists of, one or more of an alumina, a silica, a silicate, an aluminosilicate, preferably a cordierite or a mullite, an aluminotitanate, a silicon carbide, a zirconia, a magnesia, preferably a spinel, and a titania, more preferably one or more of a silicon carbide and a cordierite, more preferably a cordierite, or wherein the substrate of the first catalyst comprises, preferably consists of, a metallic substance, wherein the metallic substance preferably comprises, more preferably consists of, oxygen and one or more of iron, chromium, and aluminum. 16. The exhaust gas treatment system of any one of embodiments 1 to 15, wherein the substrate of the first catalyst is a monolith, preferably a honeycomb monolith, more preferably a flow-through honeycomb monolith. 17. The exhaust gas treatment system of any one of embodiments 1 to 16, wherein the substrate of the first catalyst has a substrate length and wherein the coating of the first catalyst is disposed on 20 to 100 %, preferably on 50 to 100 %, more preferably on 75 to 100 %, more preferably on 95 to 100 %, more preferably on 99 to 100 % of the substrate length. 18. The exhaust gas treatment system of any one of embodiments 1 to 17, wherein the coating of the first catalyst comprises palladium at a loading in the range of from 0.035 to 2.82 g / l (1 to 80 g / ft 3< ), preferably in the range of from 0.53 to 2.12 g / l (15 to 60 g / ft 3< ), more preferably in the range of from 0.71 to 1.77 g / l (20 to 50 g / ft 3< ), more preferably in the range of from 0.88 to 1.59 g / l (25 to 45 g / ft 3< ), more preferably in the range of from 0.88 to 1.24 g / l (25 to 35 g / ft 3< ). 19. The exhaust gas treatment system of any one of embodiments 1 to 18, wherein the coating of the first catalyst comprises the zeolitic material at a loading in the range of from 61.02 to 274.61 g / l (1.0 to 4.5 g / in 3< ), preferably in the range of from 91.54 to 244.10 g / l (1.5 to 4.0 g / in 3< ), more preferably in the range of from 122.05 to 183.07 g / l (2.0 to 3.0 g / in 3< ), more preferably in the range of from 128.15 to 170.87 g / l (2.1 to 2.8 g / in 3< ), more preferably in the range of from 128.15 to 158.66 g / l (2.1 to 2.6 g / in 3< ). 20. The exhaust gas treatment system of any one of embodiments 1 to 19, wherein the coating of the first catalyst comprises the vanadium oxide at a loading in the range of from 122.04 to 366.14 g / l (2.0 to 6.0g / in 3< ), preferably in the range of from 183.07 to 335.63 g / l (3.0 to 5.5 g / in 3< ), more preferably in the range of from 244.1 to 305.12 g / l (4.0 to 5.0g / in 3< ). 21. The exhaust gas treatment system of any one of embodiments 1 to 20, 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 coating of the first catalyst comprise, preferably consist of, palladium supported on an oxidic material wherein from 99 to 100 weight-% of said oxidic material consist of zirconium and oxygen, preferably of zirconia, and a copper containing zeolitic material having a framework structure of the type CHA, and preferably a metal oxide binder as defined in embodiment 11. 22. The exhaust gas treatment system of any one of embodiments 1 to 20, 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 coating of the first catalyst comprise, preferably consist of, palladium supported on an oxidic material wherein from 99 to 100 weight-% of said oxidic material consist of zirconium and oxygen, preferably of zirconia, and a vanadium oxide supported on titania, wherein titania optionally contains one or more of tungsten and silicon. 23. The exhaust gas treatment system of any one of embodiments 1 to 22, wherein the first catalyst has a selective catalytic reduction (SCR) component and a diesel oxidation component. 24. The exhaust gas treatment system of any one of embodiments 1 to 23, wherein from 0 to 0.0035 g / l, preferably from 0 to 0.00035 g / l, more preferably from 0 to 0.000035 g / l of one or more of platinum, iridium, osmium and rhodium are comprised in the coating of the first catalyst, wherein more preferably, from 0 to 0.000035 g / l of platinum, iridium, osmium and rhodium are comprised in the coating of the first catalyst. 25. The exhaust gas treatment system of any one of embodiments 1 to 23, wherein the coating of the first catalyst is free of platinum, preferably free of platinum and rhodium, more preferably free of platinum, rhodium, iridium and osmium. 26. The exhaust gas treatment system of any one of embodiments 1 to 25, wherein from 0 to 2 weight-%, preferably from 0 to 1 weight-%, more preferably from 0 to 0.1 weight-% of the oxidic material supporting palladium comprised in the coating of the first catalyst consist of ceria and alumina, wherein more preferably from 0 to 0.1 weight-% of the oxidic material comprised in the coating of the first catalyst consists of ceria, alumina, titania, lanthana and baria; or wherein the oxidic material supporting palladium comprised in the coating of the first catalyst is free of ceria and alumina, preferably free of ceria, alumina and titania, more preferably free of ceria, alumina, titania, lanthana and baria. 27. The exhaust gas treatment system of any one of embodiments 1 to 26, wherein the second catalyst according to (ii) comprises a nitrogen oxide (NOx) reduction component and an ammonia oxidation component. 28. The exhaust gas treatment system of any one of embodiments 1 to 27, wherein the second catalyst according to (ii) is an ammonia oxidation (AMOX) catalyst. 29. The exhaust gas treatment system of any one of embodiments 1 to 28, wherein the coating of the second catalyst according to (ii) comprises a zeolitic material comprising one or more of copper and iron. 30. The exhaust gas treatment system of any one of embodiments 1 to 29, wherein the zeolitic material comprised in the coating of the second catalyst has a framework structure of the type AEI, GME, CHA, MFI, BEA, FAU, MOR or mixtures of two or more thereof, preferably a framework structure of the type AEI, CHA, BEA or mixtures of two or more thereof, more preferably a framework structure of the type CHA or AEI, more preferably a framework structure of the type CHA. 31. The exhaust gas treatment system of any one of embodiments 1 to 30, wherein the zeolitic material comprised in the coating of the second catalyst, preferably which has a framework type CHA, has a mean crystallite size of at least 0.5 micrometer, preferably in the range of from 0.5 to 1.5 micrometers, more preferably in the range of from 0.6 to 1.0 micrometer, more preferably in the range of from 0.6 to 0.8 micrometer determined via scanning electron microscopy. 32. The exhaust gas treatment system of any one of embodiments 29 to 31, wherein the zeolitic material comprised in the coating of the second catalyst comprises copper, wherein the amount of copper comprised in the zeolitic material, calculated as CuO, is preferably in the range of from 0.1 to 10.0 weight-%, more preferably in the range of from 2.0 to 7.0 weight-%, more preferably in the range of from 2.5 to 5.5 weight-%, more preferably in the range of from 2.5 to 3.5 weight-%, based on the total weight of the zeolitic material; wherein the amount of iron comprised in the zeolitic material, calculated as Fe 2 O 3 , is more preferably in the range of from 0 to 0.01 weight-%, more preferably in the range of from 0 to 0.001 weight-%, more preferably in the range of from 0 to 0.0001 weight-%, based on the total weight of the zeolitic material. 33. The exhaust gas treatment system of any one of embodiments 29 to 32, wherein from 95 to 100 weight-%, preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the framework structure of the zeolitic material consist to Si, Al, O, and optionally one or more of H and P, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO 2 : Al 2 O 3 , is preferably in the range of from 2:1 to 50:1, more preferably in the range of from 4:1 to 40:1, more preferably in the range of from 10:1 to 40: 1, more preferably in the range of from 20: 1 to 35: 1. 34. The exhaust gas treatment system of any one of embodiments 29 to 31, 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 Fe 2 O 3 , is preferably in the range of from 0.1 to 10.0 weight-%, more preferably in the range of from 1.0 to 7.0 weight-%, more preferably in the range of from 2.5 to 5.5 weight-%, based on the total weight of the zeolitic material, and wherein preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the framework structure of the zeolitic material consist to Si, Al, O, and optionally one or more of H and P, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO 2 : Al 2 O 3 , is preferably in the range of from 2:1 to 50:1, more preferably in the range of from 4:1 to 40:1, more preferably in the range of from10:1 to 40: 1, more preferably in the range of from 20: 1 to 35: 1. 35. The exhaust gas treatment system of any one of embodiments 1 to 34, wherein the coating of the second catalyst further comprises a metal oxide binder, wherein the metal oxide binder preferably comprises one or more of zirconia, alumina, titania, silica, and a mixed oxide comprising two or more of Zr, Al, Ti, and Si, more preferably comprises one or more of alumina and zirconia, more preferably comprises zirconia; wherein the coating of the second catalyst more preferably comprises the metal oxide binder in the coating at a loading in the range of from 1.22 to 12.20 g / l (0.02 to 0.2 g / in 3< ), more preferably in the range of from 4.27 to 9.15 g / l (0.07 to 0.15 g / in 3< ). 36. The exhaust gas treatment system of any one of embodiments 1 to 35, wherein the platinum group metal comprised in the coating of the second catalyst is one or more of platinum, palladium and rhodium, preferably one or more of platinum and palladium. 37. The exhaust gas treatment system of embodiment 36, wherein the platinum group metal comprised in the coating of the second catalyst is a mixture of platinum and palladium; wherein the weight ratio of platinum: palladium, calculated as elemental platinum and elemental palladium, comprised in the coating of the second catalyst, is preferably in the range of from 1:1 to 30:1, more preferably in the range of from 5:1 to 20:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1. 38. The exhaust gas treatment system of embodiment 36, wherein the platinum group metal comprised in the coating of the second catalyst is platinum. 39. The exhaust gas treatment system of any one of embodiments 1 to 38, wherein the oxidic material supporting the platinum group metal comprised in the coating of the second catalyst comprises, preferably consists of, one or more of alumina, zirconia, silica, titania and ceria, preferably one or more of alumina, silica and zirconia, more preferably one or more of zirconia and alumina. 40. The exhaust gas treatment system of any one of embodiments 1 to 39, wherein from 20 to 100 weight-%, preferably from 40 to 100 weight-%, more preferably from 60 to 100 weight-%, more preferably from 70 to 90 weight-%, more preferably from 75 to 85 weight-% of the oxidic material supporting the platinum group metal comprised in the coating of the second catalyst consist of alumina. 41. The exhaust gas treatment system of any one of embodiments 1 to 40, wherein the coating of the second catalyst comprises a vanadium oxide, wherein the vanadium oxide is preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony. 42. The exhaust gas treatment system of embodiment 41, wherein the vanadium oxide is supported on an oxidic material comprising one or more of titanium, silicon and zirconium, preferably an oxidic material comprising one or more of titanium and silicon, more preferably an oxidic material comprising one or more of titania and silica, more preferably on titania, wherein titania optionally contains one or more of tungsten and silicon. 43. The exhaust gas treatment system of any one of embodiments 1 to 42, wherein the coating of the second catalyst comprises a tungsten oxide, wherein the tungsten oxide is preferably a tungsten trioxide, wherein the tungsten oxide optionally contains one or more of iron and antimony. 44. The exhaust gas treatment system of embodiment 43, wherein the tungsten oxide is supported on an oxidic material comprising one or more of titanium and zirconium, preferably an oxidic material comprising one or more of titania and zirconia, more preferably on titania. 45. The exhaust gas treatment system of any one of embodiments 1 to 44, wherein the coating of the second catalyst comprises a vanadium oxide and a tungsten oxide, wherein the tungsten oxide is a tungsten trioxide, wherein the vanadium oxide is preferably supported on an oxidic material comprising one or more of titanium, silicon and zirconium, preferably an oxidic material comprising one or more of titanium and silicon, more preferably an oxidic material comprising one or more of titania and zirconia, more preferably on titania, wherein titania optionally contains one or more of tungsten and silicon, and the tungsten oxide is preferably supported on an oxidic material comprising one or more of titanium and zirconium, preferably an oxidic material comprising one or more of titania and zirconia, more preferably on titania. 46. The exhaust gas treatment system of any one of embodiments 1 to 45, wherein the substrate of the second catalyst comprises a ceramic or metallic substance. 47. The exhaust gas treatment system of any one of embodiments 1 to 46, wherein the substrate of the second catalyst comprises, preferably consists of, a ceramic substance, wherein the ceramic substance preferably comprises, more preferably consists of, one or more of an alumina, a silica, a silicate, an aluminosilicate, preferably a cordierite or a mullite, an aluminotitanate, a silicon carbide, a zirconia, a magnesia, preferably a spinel, and a titania, more preferably one or more of a silicon carbide and a cordierite, more preferably a cordierite. 48. The exhaust gas treatment system of any one of embodiments 1 to 46, wherein the substrate of the second catalyst comprises, preferably consists of, a metallic substance, wherein the metallic substance preferably comprises, more preferably consists of, oxygen and one or more of iron, chromium, and aluminum. 49. The exhaust gas treatment system of any one of embodiments 1 to 48, wherein the substrate of the second catalyst is a monolith, preferably a honeycomb monolith, more preferably a flow-through honeycomb monolith. 50. The exhaust gas treatment system of any one of embodiments 1 to 49, wherein the substrate of the second catalyst has a substrate length and wherein the coating of the second catalyst is disposed on 20 to 100 %, preferably on 50 to 100 %, more preferably on 75 to 100 %, more preferably on 95 to 100 %, more preferably on 99 to 100 % of the substrate length. 51. The exhaust gas treatment system of any one of embodiments 1 to 50, wherein the coating of the second catalyst comprises the platinum group metal, calculated as elemental platinum group metal, at a loading in the range of from 0.035 to 0.53 g / l (1 to 15 g / ft 3< ), preferably in the range of from 0.11 to 0.35 g / l (3 to 10 g / ft 3< ), more preferably in the range of from 0.16 to 0.32 g / l (4.5 to 9.0 g / ft 3< ), more preferably in the range of from 0.26 to 0.30 g / l (7.5 to 8.5 g / ft 3< ). 52. The exhaust gas treatment system of any one of embodiments 1 to 51, wherein the coating of the second catalyst comprises the zeolitic material at a loading in the range of from 30.51 to 335.63 g / l (0.5 to 5.5 g / in 3< ), more preferably in the range of from 91.54 to 305.12 g / l (1.5 to 5.0 g / in 3< ), more preferably in the range of from 122.05 to 244.09 g / l (2.0 to 4.0 g / in 3< ), more preferably in the range of from 122.05 to 213.58 g / l (2.0 to 3.5 g / in 3< ). 53. The exhaust gas treatment system of any one of embodiments 1 to 52, wherein the coating of the second catalyst comprises one or more of a vanadium oxide and a tungsten oxide at a loading in the range of from 122.04 to 366.14 g / l (2.0 to 6.0 g / in 3< ), preferably in the range of from 183.07 to 335.63 g / l (3.0 to 5.5 g / in 3< ), more preferably in the range of from 244.1 to 305.12 g / l (4.0 to 5.0g / in 3< ). 54. The exhaust gas treatment system of any one of embodiments 1 to 37 and 46 to 52, wherein the coating of the second catalyst comprises, preferably consists of, a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt: Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, on an oxidic material comprising a mixture of zirconia and alumina, a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 36. 55. The exhaust gas treatment system of any one of embodiments 1 to 54, 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 coating of the second catalyst comprise a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt: Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, supported on an oxidic material comprising a mixture of zirconia and alumina and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 36. 56. The exhaust gas treatment system of any one of embodiments 1 to 54, wherein the coating of the first catalyst comprises, preferably consists of, palladium supported on an oxidic material comprising zirconium, preferably consisting of zirconia, and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 11, and wherein the coating of the second catalyst comprises, preferably consists of, a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt: Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, supported on an oxidic material comprising a mixture of zirconia and alumina and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 36. 57. The exhaust gas treatment system of any one of embodiments 1 to 54, wherein the coating of the first catalyst comprises, preferably consists of, palladium supported on an oxidic material comprising zirconium, preferably consisting of zirconia, and a vanadium oxide supported on titania, wherein the vanadium oxide is more preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony, and wherein the coating of the second catalyst comprises, preferably consists of, a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt: Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, supported on an oxidic material comprising a mixture of zirconia and alumina and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 36. 58. The exhaust gas system of embodiment 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 coating of the first catalyst comprises palladium supported on an oxidic material consisting of zirconia and a zeolitic material having a framework structure type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 11, and 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 coating of the second catalyst comprises a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt: Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, supported on an oxidic material comprising a mixture of zirconia and alumina and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 36. 59. The exhaust gas system of embodiment 57, 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 coating of the first catalyst comprises palladium supported on an oxidic material consisting of zirconia and a vanadium oxide supported on titania, wherein the vanadium oxide is more preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony, and 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 coating of the second catalyst comprises a mixture of platinum and palladium, wherein the weight ratio of platinum relative to palladium, calculated as Pt:Pd, is preferably in the range of from 5:1 to 15:1, more preferably in the range of from 8:1 to 12:1, more preferably in the range of from 9:1 to 11:1, supported on an oxidic material comprising a mixture of zirconia and alumina and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 36. 60. The exhaust gas treatment system of any one of embodiments 1 to 53, wherein the coating of the second catalyst comprises, preferably consists of, platinum supported on an oxidic material comprising a mixture of zirconia and alumina and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 36. 61. The exhaust gas treatment system of any one of embodiments 1 to 53, 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 coating of the second catalyst comprise platinum supported on an oxidic material comprising a mixture of zirconia and alumina and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 36. 62. The exhaust gas treatment system of any one of embodiments 1 to 53, wherein the coating of the first catalyst comprises, preferably consists of, palladium supported on an oxidic material comprising zirconium, preferably consisting of zirconia, and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 11, and wherein the coating of the second catalyst comprises, preferably consists of, platinum supported on an oxidic material comprising a mixture of zirconia and alumina and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 36. 63. The exhaust gas treatment system of any one of embodiments 1 to 53, wherein the coating of the first catalyst comprises, preferably consists of, palladium supported on an oxidic material comprising zirconium, preferably consisting of zirconia, and a vanadium oxide supported on titania, wherein the vanadium oxide is more preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony, and wherein the coating of the second catalyst comprises, preferably consists of, platinum supported on an oxidic material comprising a mixture of zirconia and alumina and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 36. 64. The exhaust gas system of embodiment 62, 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 coating of the first catalyst comprises palladium supported on an oxidic material consisting of zirconia, a zeolitic material having a framework structure type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 11, and 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 coating of the second catalyst comprises platinum supported on an oxidic material comprising a mixture of zirconia and alumina and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 36. 65. The exhaust gas system of embodiment 63, 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 coating of the first catalyst comprises palladium supported on an oxidic material consisting of zirconia and a vanadium oxide supported on titania, wherein the vanadium oxide is more preferably one or more of a vanadium (V) oxide and a vanadium (IV) oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony, and 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 coating of the second catalyst comprises platinum supported on an oxidic material comprising a mixture of zirconia and alumina and a zeolitic material having a framework structure of the type CHA and comprising copper, and preferably a metal oxide binder as defined in embodiment 36. 66. The exhaust gas treatment system of any one of embodiments 1 to 65, wherein the substrate of the first catalyst comprises, preferably consists of, a cordierite and the substrate of the second catalyst comprises, preferably consists of, a cordierite. 67. The exhaust gas treatment system of any one of embodiments 1 to 66, wherein the substrate of the first catalyst on which substrate the coating of the first catalyst is disposed, is a first substrate and the substrate of the second catalyst on which substrate the coating of the second catalyst is disposed, is a second substrate, wherein the first substrate and the second substrate are different from each other. 68. The exhaust gas treatment system of any one of embodiments 1 to 67, wherein the substrate of the first catalyst has a substrate length in the range of from 2.54 to 25.4 cm (1 to 10 inches), preferably in the range of from 5.08 to 20.32 cm (2 to 8 inches), more preferably in the range of from 10.16 to 19.05 cm (4 to 7.5 inches), more preferably in the range of from 12.7 to 17.78 cm (5 to 7 inches). 69. The exhaust gas treatment system of any one of embodiments 1 to 68, wherein the substrate of the second catalyst has a substrate length in the range of from 2.54 to 25.4 cm (1 to 10 inches), preferably in the range of from 3.81 to 17.78 cm (1.5 to 7 inches), more preferably in the range of from 5.08 to 12.7 cm (2 to 5 inches), more preferably in the range of from 5.08 to 10.16 cm (2 to 4 inches). 70. The exhaust gas treatment system of embodiment 68 or 69, wherein the length of the first substrate is greater than the length of the second substrate, wherein the ratio of the length of the first substrate relative to the length of the second substrate is preferably in the range of from 1.1:1 to 4:1, preferably in the range of from 1.5:1 to 3.5:1, more preferably in the range of from 1.9:1 to 2.1:1. 71. The exhaust gas treatment system of any one of embodiments 1 to 70, wherein the substrate of the first catalyst has a substrate width in the range of from 10.16 to 43.18 cm (4 to 17 inches), preferably in the range of from 17.78 to 38.10 cm (7 to 15 inches), more preferably in the range of from 20.32 to 35.56 cm (8 to 14 inches), more preferably in the range of from 22.86 to 33.02 cm (9 to 13 inches), more preferably in the range of from 22.86 to 27.94 cm (9 to 11 inches). 72. The exhaust gas treatment system of any one of embodiments 1 to 71, wherein the substrate of the second catalyst has a substrate width in the range of from 10.16 to 43.18 cm (4 to 17 inches), preferably in the range of from 17.78 to 38.10 cm (7 to 15 inches), more preferably in the range from 20.32 to 35.56 cm (8 to 14 inches), more preferably in the range of from 22.86 to 33.02 cm (9 to 13 inches), more preferably in the range of from 22.86 to 27.94 cm (9 to 11 inches). 73. The exhaust gas treatment system of any one of embodiments 1 to 66 and 68 to 72, wherein the substrate of the first catalyst, on which substrate the coating of the first catalyst is disposed, and the substrate of the second catalyst, on which substrate the coating of the second catalyst is disposed, together form a single substrate, wherein said single substrate comprises an inlet end and an outlet end, wherein the inlet end is arranged upstream of the outlet end, and wherein the coating of the first catalyst is disposed on said single substrate from the inlet end towards the outlet end of said single substrate and the coating of the second catalyst is disposed on said single substrate from the outlet end towards the inlet end of said single substrate , wherein the coating of the first catalyst covers from 25 to 75 % of the substrate length and the coating of the second catalyst covers from 25 to 75 % of the substrate length. 74. The exhaust gas treatment system of embodiment 73, wherein the coating of the first catalyst covers from 25 to 70 %, preferably from 35 to 65 %, more preferably from 45 to 55 %, of the substrate length and the coating of the second catalyst covers from 25 to 70 %, preferably from 35 to 65 %, more preferably on from 45 to 55 % of the substrate length. 75. The exhaust gas treatment system of embodiment 73, wherein the coating of the first catalyst covers from 50 to 75 %, preferably from 69 to 75 % of the substrate length and the coating of the second catalyst covers from 25 to 50 %, preferably from 25 to 31 % of the substrate length. 76. The exhaust gas treatment system of any one of embodiments 73 to 75, wherein the coating of the first catalyst and the coating of the second catalyst overlap. 77. The exhaust gas treatment system of any one of embodiments 73 to 75, wherein there is a gap between the coating of the first catalyst and the coating of the second catalyst. 78. The exhaust gas treatment system of any one of embodiments 1 to 77, wherein the first catalyst comprises no further coating. 79. The exhaust gas treatment system of any one of embodiments 1 to 78, wherein the second catalyst comprises no further coating. 80. The exhaust gas treatment system of any one of embodiments 1 to 79, further comprising an injector for injecting a fluid into the exhaust gas stream exiting the diesel engine, said injector being located upstream of the first catalyst and downstream of the upstream end of the exhaust gas treatment system. 81. The exhaust gas treatment system of embodiment 80, wherein the fluid is an aqueous urea solution. 82. The exhaust gas treatment system of any one of embodiments 1 to 81, further comprising one or more of a diesel oxidation catalyst, a nitrogen oxides reduction catalyst and an ammonia oxidation catalyst located downstream of the second catalyst according to (ii). 83. The exhaust gas treatment system of any one of embodiments 1 to 82, further comprising a particulate filter, wherein the particulate filter has an inlet end and an outlet end and is located downstream of the second catalyst according to (ii), preferably wherein the outlet end of the second catalyst according to (ii) is in fluid communication with the inlet end of the particulate filter and wherein between the outlet end of the second catalyst according to (ii) and the inlet end of the particulate filter, no catalyst for treating the exhaust gas stream exiting the second catalyst is located in the exhaust gas treatment system. 84. The exhaust gas treatment system of embodiment 83, wherein the particulate filter is a catalyzed particulate filter. 85. The exhaust gas treatment system of embodiment 82, comprising a diesel oxidation catalyst and a particulate filter, preferably a catalyzed particulate filter, wherein the diesel oxidation catalyst has an inlet end and an outlet end and is located downstream of the second catalyst according to (ii) and the particulate filter is located downstream of the diesel oxidation catalyst towards the downstream end of the exhaust gas treatment system. 86. The exhaust gas treatment system of embodiment 85, wherein the outlet end of the second catalyst according to (ii) is in fluid communication with the inlet end of the diesel oxidation catalyst and wherein between the outlet end of the second catalyst according to (li) and the inlet end of the diesel oxidation catalyst, no catalyst for treating the exhaust gas stream exiting the second catalyst is located in the exhaust gas treatment system. 87. 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 diesel engine comprising one or more of NOx, ammonia, nitrogen monoxide and a hydrocarbon; (2) passing the exhaust gas stream provided in (1) through the exhaust gas system according to any one of embodiments 1 to 86.

[0103] The present invention is further illustrated by the following Reference Examples, Comparative Examples, and Examples.Examples Reference Example 1: Determination of the Dv90 values

[0104] The particle size distributions were determined by a static light scattering method using Sym-patec HELOS equipment, wherein the optical concentration of the sample was in the range of from 5 to 10 %.Reference Example 2: Preparation of a CuCHA zeolite

[0105] The zeolitic material having the framework structure type CHA comprising Cu and used in the examples herein was prepared according to the teaching of US 8 293 199 B2. Particular reference is made to Inventive Example 2 of US 8 293 199 B2, column 15, lines 26 to 52.Reference Example 3: Preparation of a second catalyst of the exhaust gas system of the present invention, an AMOX catalyst

[0106] A mixture of a platinum precursor with platinum as an ammine stabilized hydroxo Pt(IV) complex, with a solid content of 16 % by weight, and a mixture of a palladium precursor with palladium as the cation complex to a nitrate anion, with a solid content of 19% by weight, with a platinum to palladium weight ratio of 10:1 were added dropwise into 15.26 g / l (0.25 g / in 3< ) alumina (Al 2 O 3 (about 80 weight-%), doped with about 20 weight-% ZrO 2 , having a BET specific surface area of about 202.5 m 2< / g, a Dv90 of 125 micrometers and a total pore volume of about 0.425 ml / g) under constant stirring, thereby performing an incipient wetness impregnation. The amount of liquids added was suitably calculated to fill the pore volume of the zirconia-alumina. The final solid content after incipient wetness was approximately 75 % by weight. The resulting mixture after incipient wetness impregnation was pre-calcined at 590 °C for 4 hours to remove any moisture and to fix the platinum and palladium onto the metal oxide support material giving a dry platinum / palladium content of 0.28 g / l (8 g / ft 3< ).

[0107] Separately, a mixture with solids corresponding to 7,93 g / l (0.13 g / in 3< ) (calculated as ZrO 2 ) zirconyl-acetate with a solid content of 30 % by weight was added to water to create a mixture with a solid content of approximately 3 % by weight. To this, Cu-CHA zeolite slurry prepared according to Reference Example 2 herein except that the zeolite was spray-dried, and corresponding to 167.7 g / l (2.75 g / in 3< ) of washcoat loading was added. The resulting slurry was then milled until the resulting Dv90 determined as described in Reference Example 1 herein was 5 micrometers.

[0108] Subsequently, the pre-calcined Pt / Pd impregnated zirconia-alumina was made into a slurry. Firstly, tartaric acid in a ratio of 5 / 1 of the amount of Pt and Pd remaining after pre-calcination was added to water as was monoethanolamine in a ratio of 1 / 10 of the amount of tartaric acid. Secondly, the Pt / Pd impregnated zirconia-alumina was added to this solution and mixed into the solution thereby forming a Pt / Pd containing slurry. The slurry was then milled until the Dv90 determined as described in Reference Example 1 herein was 10 micrometers. To this Pt / Pd containing slurry, the direct exchanged Cu-CHA zeolite slurry was added and mixed, creating the final slurry that is ready for disposal.

[0109] The final slurry was then disposed over the full length of honeycomb cordierite monolith substrate (diameter: 26.67 cm (10.5 inches) × length: 7.62 cm (3 inches) cylindrically shaped substrate with 400 / (2.54) 2< cells per square centimeter and 0.1 millimeter (4 mil) wall thickness). Afterwards, the substrate was dried at 120 °C for 10 minutes and at 160 °C for 30 minutes and was then calcined at 450 °C for 30 minutes. The washcoat loading after calcination was 183.07 g / l (3.0 g / in 3< ).Reference Example 4: Preparation of a SCR catalyst not according to the present invention

[0110] 6.10 g / l (0.1 g / in 3< ) (calculated as ZrO 2 ) of zirconyl-acetate mixture with a solid content of 30 % by weight were added to water to create a mixture with a solid content of approximately 3 % by weight. To this, 122.05 g / l (2.0 g / in 3< ) of a Cu-CHA zeolite prepared according to Reference Example 2 herein except that the zeolite was spray-dried, were added. The resulting slurry was then milled until the resulting Dv90 determined as described in Reference Example 1 herein was 10 micrometers. The final slurry was then disposed over the full length of honeycomb cordierite monolith substrate (diameter: 26.67 cm (10.5 inches) × length: 15.24 cm (6 inches) cylindrically shaped substrate with 400 / (2.54) 2< cells per square centimeter and 0.1 millimeter (4 mil) wall thickness). Afterwards, the substrate was dried at 120 °C for 10 minutes and at 160 °C for 30 minutes and was then calcined at 450 °C for 30 minutes. The washcoat loading after calcination was 128.15 g / l (2.1 g / in 3< ).Reference Example 5: Preparation of an AMOX catalyst

[0111] An aqueous mixture of a platinum precursor with platinum as an ammine stabilized hydroxo Pt(IV) complex, with a solid content of 16,5% by weight was added dropwise into 15.26 g / l (0.25 g / in 3< ) alumina (Al 2 O 3 (about 80 weight-%) doped with about 20 weight-% ZrO 2 having a BET surface area of about 202.5 m 2< / g, a Dv90 of 125 micrometers and a total pore volume of 0.425 ml / g) under constant stirring, thereby performing an incipient wetness impregnation. The amount of liquids added was suitably calculated to fill the pore volume of the zirconia-alumina. The final solid content after incipient wetness was approximately 75 % by weight.

[0112] The resulting mixture after incipient wetness impregnation was pre-calcined at 590 °C for 4 hours to remove any moisture and to fix the platinum onto the metal oxide support material giving a dry platinum content of 0.28 g / l (8 g / ft 3< ).

[0113] Separately, 7.93 g / l (0.13 g / in 3< ) (calculated as ZrO 2 ) zirconyl-acetate mixture with a solid content of 30 % by weight were added to water to create a mixture with a solid content of approximately 10 % by weight. To this, 158.66 g / l (2.6 g / in 3< ) of the Cu-CHA zeolite prepared according to Reference Example 2 herein were added. The resulting slurry was then milled until the resulting Dv90 determined as described in Reference Example 1 herein was 5 micrometers.

[0114] Subsequently, the pre-calcined Pt impregnated zirconia-alumina was made into a slurry. Firstly, tartaric acid in a ratio of 5 / 1 of the amount of Pt remaining after pre-calcination was added to water as was monoethanolamine in a ratio of 1 / 10 of the amount of tartaric acid. Secondly, the Pt impregnated zirconia-alumina was added to this solution and mixed into the solution thereby forming a Pt containing slurry. The slurry was then milled until the Dv90 determined as described in Reference Example 1 herein was 10 micrometers.

[0115] To this Pt containing slurry, the direct exchanged Cu-CHA zeolite slurry was added and mixed, creating the final slurry that is ready for disposal.

[0116] The final slurry was then disposed over the full length of honeycomb cordierite monolith substrates (diameter: 26.67 cm (10.5 inches) × length: 7.62 cm (3 inches) cylindrically shaped substrate with 400 / (2.54) 2< cells per square centimeter and 0.1 millimeter (4 mil) wall thickness). Afterwards, the substrate was dried at 120 °C for 10 minutes and at 160 °C for 30 minutes and was then calcined at 450 °C for 30 minutes. The washcoat loading after calcination was 183.07 g / l (3.0 g / in 3< ).Reference Example 6: Measurement of the BET specific surface area

[0117] The BET specific surface area of the alumina was determined according to DIN 66131 or DIN-ISO 9277 using liquid nitrogen.Comparative Example 1: Preparation of an exhaust gas treatment system not according to the present invention

[0118] An exhaust gas treatment system not according to the present invention was prepared by combining the catalyst of Reference Example 4 and the catalyst of Reference Example 5, wherein the catalyst of Reference Example 5 was located downstream of the catalyst of Reference Example 4.Example 1: Preparation of a first catalyst according to the invention having an SCR component and a diesel oxidation component

[0119] An aqueous mixture of Pd(NO 3 ) 2 with a solid content of 19 % by weight was added dropwise into 30.51 g / l (0.5 g / in 3< ) of zirconia oxide (with a pore volume of 0.420 ml / g) with a solid content of 96% under constant stirring, thereby performing an incipient wetness impregnation. The amount of liquids added was suitably calculated to fill the pore volume of the zirconia oxide. The final solid content after incipient wetness was 65 % by weight. The resulting mixture was pre-calcined at 590 °C for 4 hours to remove any moisture and to fix the palladium onto the metal oxide support material giving a dry palladium content of 1.06 g / l (30 g / ft 3< ).

[0120] Separately, a mixture with solids corresponding to 7.32 g / l (0.12 g / in 3< ) (calculated as ZrO 2 ) of zirconyl-acetate mixture with a solid content of 30 % by weight were added to water to create a mixture with a solid content of approximately 3 % by weight. To this, 144.02 g / l (2.36 g / in 3< ) of a Cu-CHA zeolite prepared according to Reference Example 2 herein, except that the zeolite was spray-dried, were added. The resulting slurry was then milled until the resulting Dv90 determined as described in Reference Example 1 herein was 5 micrometers.

[0121] Subsequently, the pre-calcined Pd impregnated zirconia oxide was made into a slurry. Firstly, tartaric acid in a weight ratio of 5:1 of the amount of Pd was added to water as was monoethanolamine in a ratio of 1:10 of the amount of tartaric acid. Secondly, the Pd impregnated zirconia oxide was added to this solution and mixed into the solution creating a Pd / Zr containing slurry. The slurry was then milled until the Dv90 determined as described in Reference Example 1 herein was 10 micrometers. To this Pd containing slurry, the Cu-CHA zeolite slurry was added and mixed, creating the final slurry.

[0122] The final slurry was then disposed over the full length of honeycomb cordierite monolith substrate (diameter: 26.67 cm (10.5 inches) × length: 15.24 cm (6 inches) cylindrically shaped substrate with 400 / (2.54) 2< cells per square centimeter and 0.1 millimeter (4 mil) wall thickness). Afterwards, the substrate was dried at 120 °C for 10 minutes and at 160 °C for 30 minutes and was then calcined at 450 °C for 30 minutes. The washcoat loading after calcination was 183.07 g / l (3.0 g / in 3< ).Example 2: Preparation of an exhaust gas treatment system according to the present invention

[0123] An exhaust gas treatment system according to the present invention was prepared by combining the catalyst of Example 1 and the catalyst of Reference Example 3, wherein the catalyst of Reference Example 3 was located downstream of the catalyst of Example 1 as depicted in Fig-ure 1a.Example 3: Use of the exhaust gas treatment systems of Example 2 and of Comparative Example 1 - HC slip / SCR(out) Temperature

[0124] The HC slip was measured at the exit of the AMOX catalyst (HC slip AMOX(out)) for the exhaust gas treatment systems of Example 2 and the exhaust gas treatment system of comparative Example 1 at different loadpoints 1 to 7 (space velocities: 50k and 75kh -1< at decreasing SCR inlet temperatures starting at 370°C and ending at 270°C, see Table 1 below). The results are displayed in Figure 2. Table 1Measurement conditionsLoadpoints Exhaust mass flow (kg / hr) Temperature SCR(in) (°C) 198736026583603104831047443145120028767702877775268

[0125] As may be taken from Figure 2, the HC slips for the exhaust gas treatment system of Example 2 are of approximately 50 ppm at loadpoint 1, of approximately 20 ppm at loadpoint 2, approximately 210 ppm at loadpoint 3 and of less than 100 ppm at loadpoint 4. The HC slips for the exhaust gas treatment system of Comparative Example 1 are of approximately 200 ppm at loadpoints 1 and 4, less than 100 ppm at loadpoint 2 and there is a pic at loadpoint 3, where the HC slip is of more than 450 ppm. This shows that the SCR catalyst of the exhaust gas treatment system of comparative Example 1 displays no hydrocarbon functionality and that the AMOX of said comparative Example may compensate only at high SCR(in) temperature. This further shows that the exhaust gas treatment system of the present invention achieves improved hydrocarbon conversion compared to the system of Comparative Example 1, in particular due to this specific combination of two specific SCR and AMOX catalysts.

[0126] The SCR(out) temperatures for the exhaust gas treatment system of Example 2 are between 400 and 440 °C whereas the SCR(out) temperatures of the exhaust gas treatment system of comparative Example 1 are approximately equal to the SCR(in) temperatures. This illustrates that the exhaust gas treatment system of the present invention permits to create a favorable exotherm which permits to reduce the sulfur poisoning.

[0127] This example demonstrates that the exhaust gas treatment system of the present invention exhibits improved resistance to HC poisoning and to sulfur poisoning.Example 4: Use of the exhaust gas treatment system of Example 2 and of Comparative Example 1 - NOx conversion at low temperature

[0128] The NOx conversion was measured at low temperature at the entrance of the exhaust gas treatment system, namely at 225 °C. Table 2 Measurement conditionsTemperature (°C) Exhaust mass flow (kg / hr) Engine out NOx (ppm) 2254961036

[0129] As may be taken from Figure 3, the exhaust gas treatment system of Example 2 permits to obtain a NOx conversion of more than 90 % at 225 °C which is approximately equal (less than 2 % difference) to the NOx conversion obtained with the exhaust gas treatment system of comparative Example 1. This shows that the use of palladium in the SCR catalyst does not impede the NOx conversion at low temperatures, in particular at 225 °C.Example 5: Impact of HC injection on DeNOx performance

[0130] For measuring the DeNOx performance after HC injection, the relative amount of reduced NOx was measured at 203 °C for the system of Example 2 and the system of Comparative Example 1. Table 3 Measurement conditionsTemperature (°C) Exhaust mass flow (kg / hr) Engine out NOx (ppm) 203560573

[0131] The results are shown in Figure 4, wherein the exhaust gas treatment system of Example 2 shows a drop-off of less than 8 % in DeNOx while the system of Comparative Example 1 shows a drop-off of approximately 15 %. Accordingly, this example demonstrates that the exhaust gas treatment system of the present invention permits to prevent HC poisoning and / or coking of the catalyst.Brief description of the figures

[0132] In order to provide an understanding of the invention, reference is made to the appended figures, which are not necessarily drawn to scale, and in which reference numerals refer to components of the invention. Figure 1ashows a schematic depiction of an engine coupled with the exhaust gas treatment system according to the present invention and a further catalytic unit. In particular, Figure 1a shows a schematic depiction of an engine coupled with an exhaust gas treatment system according to the present invention and a further catalytic unit. The exhaust gas treatment system 1 according to the present invention is depicted on Figure 1a, said system comprises a first catalyst 2 as described in the foregoing which is located downstream of the diesel engine and downstream the inlet end of the exhaust gas treatment system 1. Optionally, a fluid injector 4 may be located upstream of the first catalyst 2 and downstream of the inlet end of the exhaust gas treatment system. Further, the system 1 comprises a second catalyst 3 as described in the foregoing which is located downstream of the first catalyst 2. The first catalyst 2 comprises a coating disposed on a substrate, both being not represented on Figure 1a. The second catalyst 3 comprises a coating disposed on a substrate, both also not represented on Figure 1a. The substrates of the catalyst 2 and the catalyst 3 are separate substrates, such that the first catalyst 2 and the second catalyst 3 are separated by a pipe or a tube 5. A further catalytic unit 6 may be disposed downstream of the exhaust gas treatment system 1, said unit 6 may be one or more of a diesel oxidation catalyst, a nitrogen oxides reduction catalyst and an ammonia oxidation. Figure 1bshows a schematic depiction of an engine coupled with the exhaust gas treatment system according to the present invention and a further catalytic unit. In particular, Figure 1b shows a schematic depiction of an engine coupled with an exhaust gas treatment system according to the present invention and a further catalytic unit. The exhaust gas treatment system 11 according to the present invention is depicted on Figure 1b, said system comprises a first catalyst 12 as described in the foregoing which is located downstream of the diesel engine and downstream the inlet end of the exhaust gas treatment system 1. Optionally, a fluid injector 4 may be located upstream of the first catalyst 12 and downstream of the inlet end of the exhaust gas treatment system. Further, the system 11 comprises a second catalyst 13 as described in the foregoing which is located downstream of the first catalyst 12. The first catalyst 12 comprises a coating disposed on a substrate, both being not represented on Figure 1a. The second catalyst 13 comprises a coating disposed on a substrate, both also not represented on Figure 1a. The substrates of the catalyst 12 and the catalyst 13 form a single substrate. For example, the coating of the first catalyst 12 may cover from 48 to 52 % of the substrate length from the inlet end to the outlet end of the substrate and the coating of the second catalyst 13 may cover from 48 to 52 % of the substrate length from the outlet end to the inlet end of the substrate with no overlap of the coatings. Alternatively, the coatings of the catalysts 12 and 13 may overlap. As a further alternative, a gap between the coatings of the first catalyst 12 and of the second catalyst 13 may be created. These alternatives are not depicted on Figure 1b. A further catalytic unit 6 may be disposed downstream of the exhaust gas treatment system 1, said unit 6 may be one or more of a diesel oxidation catalyst, a nitrogen oxides reduction catalyst and an ammonia oxidation. Figure 2shows the HC slip measured at the exit of the AMOX catalyst (HC slip AMO(out)) and the SCR(out) temperatures for the exhaust gas treatment systems of Example 2 and the exhaust gas treatment system of comparative Example 1 at different loadpoints 1 to 7. Figure 3shows the NOx conversion measured obtained by using the exhaust gas treatment systems of Example 2 and comparative Example 1 at low temperature, namely 225 °C. Figure 4shows the relative amount of reduced NOx measured at 203 °C after HC injection for the exhaust gas treatment system of Example 2 and the exhaust gas treatment system of comparative Example 1. Cited Literature

[0133] US 2001 / 0049339 US 9 480 976 US 9 352 307 US 9 321 009 US 9 199 195 US 9 138 732 US 9 011 807 US 8 715 618 US 8 293 182 US 8 119 088 US 8 101 146 US 7 220 642 US 4 518 710 US 5 137 855 US 5 476 828 US 8 685 882 US 9 101 908 DE10 2015 015260 A1 DE 10 2015 0160 986 A1 WO 2015 / 130216 A1 US 8 293 199 B2 US 2005 / 137079 A1

Claims

1. An exhaust gas treatment system for treating an exhaust gas stream exiting a diesel engine, said exhaust gas treatment system having an upstream end for introducing said exhaust gas stream into said exhaust gas treatment system, wherein said exhaust gas treatment system comprises (i) a first catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises palladium supported on an oxidic material comprising zirconium and further comprises one or more of a vanadium oxide and a zeolitic material comprising one or more of copper and iron; (ii) a second catalyst having an inlet end and an outlet end and comprising a coating disposed on a substrate, wherein the coating comprises a platinum group metal supported on an oxidic material and further comprises one or more of a vanadium oxide, a tungsten oxide and a zeolitic material comprising one or more of copper and iron; wherein the first catalyst according to (i) is the first catalyst of the exhaust gas treatment system downstream of the upstream end of the exhaust gas treatment system and wherein the inlet end of the first catalyst is arranged upstream of the outlet end of the first catalyst; wherein in the exhaust gas treatment system, the second catalyst according to (ii) is located downstream of the first catalyst according to (i) and wherein the inlet end of the second catalyst is arranged upstream of the outlet end of the second catalyst.

2. The exhaust gas treatment system of claim 1, wherein from 90 to 100 weight-%, preferably from 95 to 100 weight-%, more preferably from 99 to 100 weight-% of the oxidic material comprised in the coating of the first catalyst consist of zirconium and oxygen, preferably of zirconia.

3. The exhaust gas treatment system of claim 1 or 2, wherein from 99 to 100 weight-% of the oxidic material of the coating of the first catalyst consist of zirconium and oxygen, preferably zirconia, and the coating of the first catalyst comprises a zeolitic material comprising one or more of copper and iron.

4. The exhaust gas treatment system of any one of claims 1 to 3, wherein the coating of the first catalyst according to (i) comprises a zeolitic material comprising one or more of copper and iron, preferably wherein the zeolitic material comprises copper, wherein the amount of copper comprised in the zeolitic material, calculated as CuO, is preferably in the range of from 0.1 to 10.0 weight-%, more preferably in the range of from 2.0 to 7.0 weight-%, more preferably in the range of from 2.5 to 5.5 weight-%, more preferably in the range of from 2.5 to 3.5 weight-%, based on the total weight of the zeolitic material5. The exhaust gas treatment system of any one of claims 1 to 4, wherein the zeolitic material comprised in the coating of the first catalyst has a framework structure of the type AEI, GME, CHA, MFI, BEA, FAU, MOR or mixtures of two or more thereof, preferably a framework structure of the type AEI, CHA, BEA or mixtures of two or more thereof, more preferably a framework structure of the type CHA or AEI, more preferably a framework structure of the type CHA.

6. The exhaust gas treatment system of any one of claims 1 to 5, wherein the coating of the first catalyst comprises a vanadium oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony.

7. The exhaust gas treatment system of any one of claims 1 to 6, wherein the zeolitic material comprised in the coating of the second catalyst has a framework structure of the type AEI, GME, CHA, MFI, BEA, FAU, MOR or mixtures of two or more thereof, preferably a framework structure of the type AEI, CHA, BEA or mixtures of two or more thereof, more preferably a framework of the type CHA or AEI, more preferably a framework structure of the type CHA.

8. The exhaust gas treatment system of any one of claims 1 to 7, wherein the coating of the second catalyst comprises a vanadium oxide, wherein the vanadium oxide optionally contains one or more of tungsten, iron and antimony.

9. The exhaust gas treatment system of any one of claims 1 to 8, wherein the platinum group metal comprised in the coating of the second catalyst is one or more of platinum, palladium and rhodium.

10. A method for the simultaneous selective catalytic reduction of NOx, the oxidation of hydrocarbon, the oxidation of nitrogen monoxide and the oxidation of ammonia, comprising (1) providing an exhaust gas stream from a diesel engine comprising one or more of NOx, ammonia, nitrogen monoxide and a hydrocarbon; (2) passing the exhaust gas stream provided in (1) through the exhaust gas system according to any one of claims 1 to 9.