Patent Application
20230143338
The present invention relates to a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, a process for preparing a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, and a use of said catalyst. The present invention further relates to an exhaust gas treatment system comprising said catalyst.
U.S. 2018/0280876 A1 discloses a catalytic article having on a substrate a first inlet zone containing an ammonia slip catalyst (ASC) comprising a platinum group metal on a support and a first SCR catalyst and a second outlet zone comprising a diesel oxidation catalyst or a diesel exotherm catalyst. Further, U.S. 2018/0280877 A1 discloses catalyst articles and systems for the conversion of NOx and the conversion of ammonia. The catalysts of these prior art documents are not optimized for NO oxidation and do not discuss potential reduction of nitrous oxide at the outlet of their catalytic articles and systems. Thus, there is still a need to provide improved catalysts for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx which exhibits great catalytic activity (NH3 oxidation, NO oxidation and NOx conversion) while minimizing the nitrous oxide (N2O) formation.
Therefore, it was an object of the present invention to provide a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx which exhibits great catalytic activity (NH3 oxidation, NO oxidation and NOx conversion) while minimizing the nitrous oxide (N2O) formation. Surprisingly, it was found that the catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx according to the present invention permits to obtain great catalytic activity (NH3 oxidation, NO oxidation and NOx conversion) while reducing the nitrous oxide (N2O) formation.
Therefore, the present invention relates to a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, comprising
It is preferred that x is in the range of from 98 to 100, more preferably in the range of from 99 to 100.
It is preferred that y is in the range of from 20 to 80, more preferably in the range of from 40 to 75, more preferably in the range of from 50 to 72, more preferably in the range of from 60 to 70. It is more preferred that x is in the range of from 99 to 100 and that y is in the range of from 50 to 72, more preferably in the range of from 60 to 70.
It is preferred that the first coating (ii) comprises a zeolitic material comprising one or more of copper and iron.
As to the zeolitic material comprised in the first coating, it is preferred that it has a framework type selected from the group consisting of AEI, GME, CHA, MFI, BEA, FAU, MOR, a mixture of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of AEI, GME, CHA, BEA, FAU, MOR, a mixture of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of AEI, CHA, BEA, a mixture of two or more thereof and a mixed type of two or more thereof. It is more preferred that the zeolitic material comprised in the first coating has a framework type CHA or AEI, more preferably CHA.
Therefore, the present invention preferably relates to a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, comprising
In the context of 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 framework structure of the zeolitic material comprised in the first coating consist to Si, Al, O, and optionally one or more P and H, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO2:Al2O3, more preferably is 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 12:1 to 30:1, more preferably in the range of from 13:1 to 25:1, more preferably in the range of from 15:1 to 21:1.
As to the zeolitic material comprised in the first coating, it is preferred that it comprises copper, wherein the amount of copper comprised in the zeolitic material, calculated as CuO, more preferably is in the range of from 1 to 10 weight-%, more preferably in the range of from 2 to 8 weight-%, more preferably in the range of from 3 to 6 weight-%, more preferably in the range of from 4.5 to 6 weight-%, based on the total weight of the zeolitic material.
It is more preferred that the amount of iron, calculated as Fe2O3, comprised in the zeolitic material comprised in the first coating, is of at most 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. In other words, it is more preferred that the zeolitic material comprised in the first coating is substantially free, more preferably free, of iron.
Alternatively, it is preferred that the zeolitic material comprised in the first coating comprises iron, wherein the amount of iron comprised in the zeolitic material, calculated as Fe2O3, more preferably is 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. It is more preferred that from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, of the framework structure of the zeolitic material comprised in the first coating consist to Si, Al, O, and optionally one or more P and H, wherein in the framework structure, the molar ratio of Si to Al, calculated as SiO2:Al2O3, more preferably is 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 12:1 to 30:1, more preferably in the range of from 13:1 to 25:1, more preferably in the range of from 15:1 to 21:1.
Therefore, the present invention preferably relates to a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, comprising
In the context of the present invention, it is preferred that the first coating (ii) comprises the zeolitic material comprising one or more of copper and iron at a loading in the range of from 0.5 to 4 g/in3, more preferably in the range of from 0.75 to 3.5 g/in3, more preferably in the range of from 1 to 3 g/in3, more preferably in the range of from 1.5 to 2.5 g/in3.
It is preferred that the zeolitic material comprised in the first coating, more preferably having a framework type CHA, has a mean crystallite size of at least 0.5 micrometer, more 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.
It is preferred that the first coating further comprises a first oxidic material, wherein the first oxidic material more 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.
It is preferred that the first coating comprises the first oxidic material in an amount in the range of from 0.5 to 10 weight-%, more preferably in the range of from 1 to 7 weight-%, more preferably in the range of from 3 to 6 weight-%, based on the total weight of the zeolitic material comprised in the first coating.
It is preferred that the first coating comprises the first oxidic material at a loading in the range of from 0.01 to 0.2 g/in3, more preferably in the range of from 0.02 to 0.15 g/in3, more preferably in the range of from 0.03 to 0.10 g/in3.
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 first coating consist of a zeolitic material comprising one or more of copper and iron, and more preferably a first oxidic material as defined in the foregoing.
In the context of the present invention, it is alternatively preferred that the first coating comprises a vanadium oxide, wherein the vanadium oxide more preferably is one or more of vanadium (V) oxide, a vanadium (IV) oxide and a vanadium (III) oxide, wherein the vanadium oxide optionally comprises one or more of tungsten, iron and antimony.
It is more preferred that the vanadium oxide is supported on an oxidic support material comprising one or more of titanium, silicon and zirconium, more preferably comprising one or more of titanium and silicon, wherein the oxidic support material more preferably is one or more of titania and silica, more preferably titania and silica, wherein more preferably from 80 to 95 weight-% of the oxidic support material consist of titania.
It is preferred according to said alternative that the first coating comprises the vanadium oxide, calculated as V2O5, at a loading in the range of from 1 to 6 g/in3, more preferably in the range of from 2 to 4 g/in3.
It is preferred according to said alternative 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 first coating consist of vanadium oxide supported on said oxidic support material.
In the context of the present invention, it is preferred that from 0 to 0.001 weight-%, more preferably from 0 to 0.0001 weight-%, more preferably from 0 to 0.00001 weight-%, of the first coating consist of platinum, more preferably of platinum, palladium and rhodium, more preferably of platinum, palladium, rhodium, osmium and iridium, more preferably of any noble metals. In other words, it is preferred that the first coating is substantially free, more preferably free, of platinum, more preferably of platinum, palladium and rhodium, more preferably of platinum, palladium, rhodium, osmium and iridium, more preferably of any noble metals.
It is preferred that the catalyst comprises the first coating (ii) at a loading in the range of from 0.5 to 7 g/in3, more preferably in the range of from 1 to 5 g/in3, more preferably in the range of from 1.5 to 3 g/in3.
It is preferred that the first coating comprises, more preferably consists of, a nitrogen oxide (NOx) reduction component.
As to the second coating, it is preferred that the platinum group metal component comprised in the second coating is one or more of platinum, palladium and rhodium, more preferably one or more of platinum and palladium. It is more preferred that the platinum group metal component is platinum.
It is preferred that the second coating comprises the platinum group metal component at a loading, calculated as elemental platinum group metal, in the range of from 2 to 50 g/ft3, more preferably in the range of from 5 to 30 g/ft3, more preferably in the range of from 10 to 15 g/ft3. It is more preferred that the second coating comprises platinum at a loading, calculated as elemental platinum, in the range of from 2 to 50 g/ft3, more preferably in the range of from 5 to 30 g/ft3, more preferably in the range of from 10 to 15 g/ft3.
It is preferred that the second coating comprises the platinum group metal component at an amount in the range of from 0.1 to 3 weight-%, more preferably in the range of from 0.25 to 1.5 weight-%, more preferably in the range of from 0.5 to 1 weight-%, based on the weight of the non-zeolitic oxidic material comprised in the second coating.
It is preferred that the non-zeolitic oxidic material onto which the platinum group metal component of the second coating is supported comprises, more preferably consists of, one or more of alumina, zirconia, titania, silica, ceria, and a mixed oxide comprising two or more of Al, Zr, Ti, Si, and Ce, more preferably one or more of alumina, zirconia, titania and silica, more preferably one or more of titania and silica.
Therefore, the present invention preferably relates to a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, comprising
In the context of the present invention, as to the non-zeolitic oxidic material comprised in the second coating, it is preferred that from 90 to 100 weight-%, more preferably from 95 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, of the non-zeolitic oxidic material of the second coating consist of titania, and optionally silica. It is more preferred that from 60 to 100 weight-%, more preferably from 80 to 100 weight-%, more preferably from 85 to 95 weight-%, of the non-zeolitic oxidic material of the second coating consists of titania and wherein more preferably from 0 to 40 weight-%, more preferably from 0 to 20 weight-%, more preferably from 5 to 15 weight-%, of the non-zeolitic oxidic material of the second coating consist of silica.
It is preferred that the second coating comprises the non-zeolitic oxidic material at a loading in the range of from 0.25 to 3 g/in3, more preferably in the range of from 0.5 to 2 g/in3, more preferably in the range of from 0.75 to 1.5 g/in3.
It is preferred that the zeolitic material comprised in the second coating has a framework type selected from the group consisting of AEI, GME, CHA, MFI, BEA, FAU, MOR, a mixture of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of AEI, GME, CHA, BEA, FAU, MOR, a mixture of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of AEI, CHA, BEA, a mixture of two or more thereof and a mixed type of two or more thereof. It is more preferred that the zeolitic material of the second coating has a framework type CHA or AEI, more preferably CHA.
It is preferred that the zeolitic material comprised in the second coating comprises copper, wherein the amount of copper comprised in the zeolitic material, calculated as CuO, more preferably is in the range of from 1 to 10 weight-%, more preferably in the range of from 2 to 8 weight-%, more preferably in the range of from 3 to 6 weight-%, more preferably in the range of from 4.5 to 6 weight-%, based on the total weight of the zeolitic material. As to the second coating, it is more preferred that it comprises platinum supported on a non-zeolitic oxidic material, wherein the platinum supported on the non-zeolitic oxidic material is present in the second coating at a first loading L1, wherein the first loading is the sum of the loading of the platinum and the loading of the non-zeolitic oxidic material, wherein the non-zeolitic oxidic material comprises one or more of alumina, zirconia, titania, silica, ceria, and a mixed oxide comprising two or more of Al, Zr, Ti, Si, and Ce; and that it further comprises a zeolitic material comprising copper, wherein the zeolitic material comprising copper is present in the second coating at a second loading L2, wherein the second loading is the sum of the loading of the zeolitic material and the loading of the one or more of copper and iron, wherein the zeolitic material of the second coating has a framework type CHA or AEI, more preferably CHA.
In the context of 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 framework structure of the zeolitic material of the second coating 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 SiO2Al2O3, more preferably is 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 12:1 to 30:1, more preferably in the range of from 13:1 to 25:1, more preferably in the range of from 15:1 to 21:1.
It is more preferred that the amount of iron comprised in the zeolitic material of the second coating, calculated as Fe2O3, is of at most 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. In other words, it is more preferred that the zeolitic material of the second coating is substantially free, more preferably free, of iron.
As an alternative, it is preferred that the zeolitic material comprised in the second coating comprises iron, wherein the amount of iron comprised in the zeolitic material, calculated as Fe2O3, more preferably is 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. According to said alternative, it is preferred that from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, of the framework structure of the 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 SiO2:Al2O3, more preferably is 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 12:1 to 30:1, more preferably in the range of from 13:1 to 25:1, more preferably in the range of from 15:1 to 21:1.
In the context of the present invention, it preferred that the second coating comprises the zeolitic material comprising one or more of copper and iron at a loading in the range of from 0.05 to 2 g/in3, more preferably in the range of from 0.08 to 1 g/in3, more preferably in the range of from 0.1 to 0.5 g/in3.
It is preferred that the zeolitic material comprised in the second coating, more preferably having a framework type CHA, has a mean crystallite size of at least 0.5 micrometer, more 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.
As to the second coating, it is preferred that it further comprises a second oxidic material, wherein the second oxidic material more preferably comprises one or more of silica, alumina, titania, zirconia, and a mixed oxide comprising two or more of Si, Al, Ti and Zr, more preferably one or more of silica and alumina, more preferably silica. It is more preferred that the second coating comprises the second oxidic material at an amount in the range of from 0.5 to 10 weight-%, more preferably in the range of from 2 to 8 weight-%, more preferably in the range of from 4 to 6 weight-%, based on the total weight of the zeolitic material of the second coating.
It is preferred that the second coating comprises the second oxidic material at a loading in the range of from 0.005 to 0.05 g/in3, more preferably in the range of from 0.008 to 0.02 g/in3.
Preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably 99.5 to 100 weight-%, of the second coating consist of the platinum group metal component supported on the non-zeolitic oxidic material, the zeolitic material comprising one or more of copper and iron, and more preferably a second oxidic material as defined in the foregoing.
It is preferred that the second coating comprises, more preferably consists of, one or more nitrogen oxide (NOx) reduction components and one or more ammonia oxidation (AMOx) components.
It is preferred that the catalyst comprises the second coating at a loading in the range of from 0.5 to 5 g/in3, more preferably in the range of from 0.75 to 3 g/in3, more preferably in the range of from 1 to 2.5 g/in3.
It is preferred that, in the second coating, the ratio of the first loading, in g/l, to the second loading, in g/l, L1:L2, is in the range of from 1.1:1 to 50:1, more preferably in the range of from 1.5:1 to 30:1, more preferably in the range of from 1.75:1 to 20:1, more preferably in the range of from 2:1 to 10:1, more preferably in the range of from 2.5:1 to 8:1, more preferably in the range of from 3:1 to 6:1, more preferably in the range of from 3.5:1 to 5:1.
It is preferred that the substrate of the catalyst is a flow-through substrate or a wall-flow filter substrate, more preferably a flow-through substrate.
As to the substrate of the catalyst, it is preferred that it comprises, more preferably consists of, a ceramic substance, wherein the ceramic substance more preferably comprises, more preferably consists of, one or more of an alumina, a silica, a silicate, an aluminosilicate, more preferably a cordierite or a mullite, an aluminotitanate, a silicon carbide, a zirconia, a magnesia, more preferably a spinel, and a titania, more preferably one or more of a silicon carbide and a cordierite, more preferably a cordierite.
It is preferred that the substrate of the catalyst is a flow-through substrate comprising, more preferably consisting of, cordierite.
It is alternatively preferred as to the substrate that it comprises, more preferably consists of, a metallic substance, wherein the metallic substance more preferably comprises, more preferably consists of, oxygen and one or more of iron, chromium, and aluminum.
It is preferred that the catalyst of the present invention consists of the substrate (i), the first coating (ii) and the second coating (iii).
The present invention further relates to a method for preparing a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, preferably the catalyst according to the present invention, comprising
As to (b), it is preferred that it comprises, more preferably consists of,
As to (b.1), it is preferred that it comprises
It is preferred that in (b), more preferably (b.1), more preferably (b.1c), the weight ratio of the weight of the platinum group metal supported onto the non-zeolitic oxidic material to the weight of the zeolitic material comprising one or more of copper and iron is of at least 1.1:1, more preferably in the range of from 1.1:1 to 50:1, more preferably in the range of from 1.5:1 to 30:1, more preferably in the range of from 1.75:1 to 20:1, more preferably in the range of from 2:1 to 10:1, more preferably in the range of from 2.5:1 to 8:1, more preferably in the range of from 3:1 to 6:1, more preferably in the range of from 3.5:1 to 5:1.
It is preferred that, according to (b.4), drying is performed in a gas atmosphere having a temperature in the range of from 90 to 180° C., wherein the gas atmosphere more preferably comprises, more preferably is, one or more of air, lean air, and oxygen, more preferably air.
It is preferred that, according to (b.5), calcining is performed in a gas atmosphere having a temperature in the range of from 350 to 500° C. It is more preferred that the gas atmosphere comprises, more preferably is, one or more of air, lean air, and oxygen, more preferably air.
As to (c), it is preferred that it comprises, more preferably consists of,
It is preferred that, according to (c.3), drying is performed in a gas atmosphere having a temperature in the range of from 90 to 180° C., wherein the gas atmosphere more preferably comprises, more preferably is, one or more of air, lean air, and oxygen, more preferably air.
It is preferred that, according to (c.4), calcining is performed in a gas atmosphere having a temperature in the range of from 350 to 500° C. It is more preferred that the gas atmosphere comprises, more preferably is, one or more of air, lean air, and oxygen, more preferably air.
It is more preferred that y is in the range of from 20 to 80, more preferably in the range of from 40 to 75, more preferably in the range of from 50 to 72, more preferably in the range of from 60 to 70.
It is more preferred that disposing in one or more of (b), and (c), more preferably disposing in (b) and (c), is performed by spraying the slurry onto the substrate or by immersing the substrate into the slurry, more preferably by immersing the substrate into the slurry.
It is preferred that the method according to the present invention consists of (a), (b) and (c).
The present invention further relates to a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, preferably a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx according to the present invention, obtainable or obtained by a process according to the present invention.
The present invention further relates to a use of a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx according to the present invention for the simultaneous selective catalytic reduction of NOx, the oxidation of ammonia and the oxidation of NO.
The present invention further relates to an exhaust gas treatment system for treating an exhaust gas stream exiting an internal combustion engine, preferably 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 a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx according to the present invention and as defined above and one or more of a selective catalytic reduction catalyst, a combined selective catalytic reduction/ammonia oxidation catalyst, and a catalyzed soot filter.
It is preferred that the system comprises the catalyst according to the present invention and a selective catalytic reduction catalyst, wherein the selective catalytic reduction catalyst is positioned upstream of the catalyst according to the present invention. It is more preferred that the system further comprises a first urea injector, the urea injector being positioned upstream of the selective catalytic reduction catalyst.
It is preferred that the system further comprises a catalyzed soot filter, wherein the catalyzed soot filter is positioned downstream of the catalyst according to the present invention.
It is more preferred that the system further comprises a combined selective catalytic reduction/ammonia oxidation catalyst and a second selective catalytic reduction catalyst, wherein the combined selective catalytic reduction/ammonia oxidation catalyst is positioned downstream of the second selective catalytic reduction catalyst and the second catalytic reduction catalyst is positioned upstream of the combined selective catalytic reduction/ammonia oxidation catalyst and downstream of the catalyzed soot filter. It is more preferred that the system further comprises a second urea injector, the second urea injector being positioned downstream of the catalyzed soot filter and upstream of the second selective catalytic reduction catalyst.
The present invention further relates to a method for the simultaneous selective catalytic reduction of NOx, the oxidation of ammonia and the oxidation of nitrogen monoxide, the method comprising
The present invention is illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. In particular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as “The catalyst 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 catalyst of any one of embodiments 1, 2, 3 and 4”. Further, it is explicitly noted that the following set of embodiments is not the set of claims determining the extent of protection, but represents a suitably structured part of the description directed to general and preferred aspects of the present invention.
1. A catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, comprising
2. The catalyst of embodiment 1, wherein x is in the range of from 98 to 100, preferably in the range of from 99 to 100.
3. The catalyst of embodiment 1 or 2, wherein y is in the range of from 20 to 80, preferably in the range of from 40 to 75, more preferably in the range of from 50 to 72, more preferably in the range of from 60 to 70.
4. The catalyst of any one of embodiments 1 to 3, wherein the first coating (ii) comprises a zeolitic material comprising one or more of copper and iron.
5. The catalyst of any one of embodiments 1 to 4, wherein the zeolitic material comprised in the first coating has a framework type selected from the group consisting of AEI, GME, CHA, MFI, BEA, FAU, MOR, a mixture of two or more thereof and a mixed type of two or more thereof, preferably selected from the group consisting of AEI, GME, CHA, BEA, FAU, MOR, a mixture of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of AEI, CHA, BEA, a mixture of two or more thereof and a mixed type of two or more thereof, wherein the zeolitic material comprised in the first coating more preferably has a framework type CHA or AEI, more preferably CHA.
6. The catalyst of any one of embodiments 1 to 5, wherein from 95 to 100 weight-%, preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, of the framework structure of the zeolitic material comprised in the first coating consist to Si, Al, O, and optionally one or more P and H, wherein in the framework structure, the molar ratio of Si to Al, calculated as molar SiO2:Al2O3, preferably is 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 12:1 to 30:1, more preferably in the range of from 13:1 to 25:1, more preferably in the range of from 15:1 to 21:1.
7. The catalyst of any one of embodiments 1 to 6, wherein the zeolitic material comprised in the first coating comprises copper, wherein the amount of copper comprised in the zeolitic material, calculated as CuO, preferably is in the range of from 1 to 10 weight-%, more preferably in the range of from 2 to 8 weight-%, more preferably in the range of from 3 to 6 weight-%, more preferably in the range of from 4.5 to 6 weight-%, based on the total weight of the zeolitic material.
8. The catalyst of embodiment 7, wherein the amount of iron, calculated as Fe2O3, comprised in the zeolitic material comprised in the first coating, is of at most 0.01 weight-%, 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 catalyst of any one of embodiments 1 to 5, wherein the zeolitic material comprised in the first coating comprises iron, wherein the amount of iron comprised in the zeolitic material, calculated as Fe2O3, preferably is 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-%, more preferably from 99.5 to 100 weight-%, of the framework structure of the zeolitic material comprised in the first coating consist to Si, Al, O, and optionally one or more P and H, wherein in the framework structure, the molar ratio of Si to Al, calculated as SiO2:Al2O3, preferably is 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 12:1 to 30:1, more preferably in the range of from 13:1 to 25:1, more preferably in the range of from 15:1 to 21:1.
10. The catalyst of any one of embodiments 1 to 9, wherein the first coating (ii) comprises the zeolitic material comprising one or more of copper and iron at a loading in the range of from 0.5 to 4 g/in3, preferably in the range of from 0.75 to 3.5 g/in3, more preferably in the range of from 1 to 3 g/in3, more preferably in the range of from 1.5 to 2.5 g/in3.
11. The catalyst of any one of embodiments 1 to 10, wherein the zeolitic material comprised in the first coating, preferably having 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.
12. The catalyst of any one of embodiments 1 to 11, wherein the first coating further comprises a first oxidic material, wherein the first oxidic material 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.
13. The catalyst of embodiment 12, wherein the first coating comprises the first oxidic material in an amount in the range of from 0.5 to 10 weight-%, preferably in the range of from 1 to 7 weight-%, more preferably in the range of from 3 to 6 weight-%, based on the total weight of the zeolitic material comprised in the first coating; wherein the first coating preferably comprises the first oxidic material at a loading in the range of from 0.01 to 0.2 g/in3, more preferably in the range of from 0.02 to 0.15 g/in3, more preferably in the range of from 0.03 to 0.10 g/in3.
14. The catalyst of any one of embodiments 1 to 13, 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 first coating consist of a zeolitic material comprising one or more of copper and iron, and preferably a first oxidic material as defined in embodiment 13.
15. The catalyst of any one of embodiments 1 to 3, wherein the first coating comprises a vanadium oxide, wherein the vanadium oxide preferably is one or more of vanadium (V) oxide, a vanadium (IV) oxide and a vanadium (III) oxide, wherein the vanadium oxide optionally comprises one or more of tungsten, iron and antimony.
16. The catalyst of embodiment 15, wherein the vanadium oxide is supported on an oxidic support material comprising one or more of titanium, silicon and zirconium, preferably comprising one or more of titanium and silicon, wherein the oxidic support material more preferably is one or more of titania and silica, more preferably titania and silica, wherein preferably from 80 to 95 weight-% of the oxidic support material consist of titania.
17. The catalyst of embodiment 15 or 16, wherein the first coating comprises the vanadium oxide, calculated as V2O5, at a loading in the range of from 1 to 6 g/in3, preferably in the range of from 2 to 4 g/in3.
18. The catalyst of any one of embodiments 15 to 17, 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 first coating consist of vanadium oxide supported on said oxidic support material.
19. The catalyst of any one of embodiments 1 to 18, wherein from 0 to 0.001 weight-%, preferably from 0 to 0.0001 weight-%, more preferably from 0 to 0.00001 weight-%, of the first coating consist of platinum, preferably of platinum, palladium and rhodium, more preferably of platinum, palladium, rhodium, osmium and iridium, more preferably of any noble metals.
20. The catalyst of any one of embodiments 1 to 19, wherein the catalyst comprises the first coating (ii) at a loading in the range of from 0.5 to 7 g/in3, preferably in the range of from 1 to 5 g/in3, more preferably in the range of from 1.5 to 3 g/in3.
21. The catalyst of any one of embodiments 1 to 20, wherein the first coating comprises, preferably consists of, a nitrogen oxide (NOx) reduction component.
22. The catalyst of any one of embodiments 1 to 21, wherein the platinum group metal component comprised in the second coating is one or more of platinum, palladium and rhodium, preferably one or more of platinum and palladium, wherein the platinum group metal component more preferably is platinum.
23. The catalyst of any one of embodiments 1 to 22, wherein the second coating comprises the platinum group metal component at a loading, calculated as elemental platinum group metal, in the range of from 2 to 50 g/ft3, preferably in the range of from 5 to 30 g/ft3, more preferably in the range of from 10 to 15 g/ft3.
24. The catalyst of any one of embodiments 1 to 23, wherein the second coating comprises the platinum group metal component at an amount in the range of from 0.1 to 3 weight-%, preferably in the range of from 0.25 to 1.5 weight-%, more preferably in the range of from 0.5 to 1 weight-%, based on the weight of the non-zeolitic oxidic material comprised in the second coating.
25. The catalyst of any one of embodiments 1 to 24, wherein the non-zeolitic oxidic material onto which the platinum group metal component of the second coating is supported comprises, preferably consists of, one or more of alumina, zirconia, titania, silica, ceria, and a mixed oxide comprising two or more of Al, Zr, Ti, Si, and Ce, preferably one or more of alumina, zirconia, titania and silica, more preferably one or more of titania and silica.
26. The catalyst of embodiment 25, wherein from 90 to 100 weight-%, preferably from 95 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, of the non-zeolitic oxidic material of the second coating consist of titania, and optionally silica;
wherein preferably from 60 to 100 weight-%, more preferably from 80 to 100 weight-%, more preferably from 85 to 95 weight-%, of the non-zeolitic oxidic material of the second coating consists of titania and wherein preferably from 0 to 40 weight-%, more preferably from 0 to 20 weight-%, more preferably from 5 to 15 weight-%, of the non-zeolitic oxidic material of the second coating consist of silica.
27. The catalyst of any one of embodiments 1 to 26, wherein the second coating comprises the non-zeolitic oxidic material at a loading in the range of from 0.25 to 3 g/in3, preferably in the range of from 0.5 to 2 g/in3, more preferably in the range of from 0.75 to 1.5 g/in3.
28. The catalyst of any one of embodiments 1 to 27, wherein the zeolitic material comprised in the second coating has a framework type selected from the group consisting of AEI, GME, CHA, MFI, BEA, FAU, MOR, a mixture of two or more thereof and a mixed type of two or more thereof, preferably selected from the group consisting of AEI, GME, CHA, BEA, FAU, MOR, a mixture of two or more thereof and a mixed type of two or more thereof, more preferably selected from the group consisting of AEI, CHA, BEA, a mixture of two or more thereof and a mixed type of two or more thereof, wherein the zeolitic material of the second coating more preferably has a framework type CHA or AEI, more preferably CHA.
29. The catalyst of any one of embodiments 1 to 28, wherein the zeolitic material comprised in the second coating comprises copper, wherein the amount of copper comprised in the zeolitic material, calculated as CuO, preferably is in the range of from 1 to 10 weight-%, more preferably in the range of from 2 to 8 weight-%, more preferably in the range of from 3 to 6 weight-%, more preferably in the range of from 4.5 to 6 weight-%, based on the total weight of the zeolitic material.
30. The catalyst of any one of embodiments 1 to 29, wherein from 95 to 100 weight-%, preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, of the framework structure of the zeolitic material of the second coating 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 SiO2:Al2O3, preferably is 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 12:1 to 30:1, more preferably in the range of from 13:1 to 25:1, more preferably in the range of from 15:1 to 21:1.
31. The catalyst of embodiment 29 or 30, wherein the amount of iron comprised in the zeolitic material of the second coating, calculated as Fe2O3, is of at most 0.01 weight-%, 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.
32. The catalyst of any one of embodiments 1 to 26, wherein the zeolitic material comprised in the second coating comprises iron, wherein the amount of iron comprised in the zeolitic material, calculated as Fe2O3, preferably is 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-%, more preferably from 99.5 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 SiO2:Al2O3, preferably is 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 12:1 to 30:1, more preferably in the range of from 13:1 to 25:1, more preferably in the range of from 15:1 to 21:1.
33. The catalyst of any one of embodiments 1 to 32, wherein the second coating comprises the zeolitic material comprising one or more of copper and iron at a loading in the range of from 0.05 to 2 g/in3, preferably in the range of from 0.08 to 1 g/in3, more preferably in the range of from 0.1 to 0.5 g/in3.
34. The catalyst of any one of embodiments 1 to 33, wherein the zeolitic material comprised in the second coating, preferably having 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.
35. The catalyst of any one of embodiments 1 to 34, wherein the second coating further comprises a second oxidic material, wherein the second oxidic material preferably comprises one or more of silica, alumina, titania, zirconia, and a mixed oxide comprising two or more of Si, Al, Ti and Zr, more preferably one or more of silica and alumina, more preferably silica;
36. The catalyst of any one of embodiments 1 to 35, wherein from 95 to 100 weight-%, preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-%, more preferably 99.5 to 100 weight-%, of the second coating consist of the platinum group metal component supported on the non-zeolitic oxidic material, the zeolitic material comprising one or more of copper and iron, and preferably a second oxidic material as defined in embodiment 35.
37. The catalyst of any one of embodiments 1 to 36, wherein the second coating comprises, preferably consists of, one or more nitrogen oxide (NOx) reduction components and one or more ammonia oxidation (AMOx) components.
38. The catalyst of any one of embodiments 1 to 37, wherein the catalyst comprises the second coating at a loading in the range of from 0.5 to 5 g/in3, preferably in the range of from 0.75 to 3 g/in3, more preferably in the range of from 1 to 2.5 g/in3.
39. The catalyst of any one of embodiments 1 to 38, wherein, in the second coating, the ratio of the first loading, in g/l, to the second loading, in g/l, L1:L2, is in the range of from 1.1:1 to 50:1, preferably in the range of from 1.5:1 to 30:1, more preferably in the range of from 1.75:1 to 20:1, more preferably in the range of from 2:1 to 10:1, more preferably in the range of from 2.5:1 to 8:1, more preferably in the range of from 3:1 to 6:1, more preferably in the range of from 3.5:1 to 5:1.
40. The catalyst of any one of embodiments 1 to 39, wherein the substrate of the catalyst is a flow-through substrate or a wall-flow filter substrate, preferably a flow-through substrate.
41. The catalyst of any one of embodiments 1 to 40, wherein the substrate of the 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;
wherein the substrate of the catalyst preferably is a flow-through substrate comprising, more preferably consisting of, cordierite.
42. The catalyst of any one of embodiments 1 to 40, wherein the substrate of the 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.
43. The catalyst of any one of embodiments 1 to 42, consisting of the substrate (i), the first coating (ii) and the second coating (iii).
44. A method for preparing a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, preferably the catalyst according to any one of embodiments 1 to 43, comprising
45. The method of embodiment 44, wherein (b) comprises, preferably consists of,
46. The method of embodiment 45, wherein, according to (b.4), drying is performed in a gas atmosphere having a temperature in the range of from 90 to 180° C., wherein the gas atmosphere preferably comprises, more preferably is, one or more of air, lean air, and oxygen, more preferably air.
47. The method of embodiment 46 or 47, wherein, according to (b.5), calcining is performed in a gas atmosphere having a temperature in the range of from 350 to 500° C.
48. The method of embodiment 47, wherein the gas atmosphere comprises, preferably is, one or more of air, lean air, and oxygen, more preferably air.
49. The method of any one of embodiments 44 to 48, wherein (c) comprises, preferably consists of,
50. The method of embodiment 49, wherein according to (c.3), drying is performed in a gas atmosphere having a temperature in the range of from 90 to 180° C., wherein the gas atmosphere preferably comprises, more preferably is, one or more of air, lean air, and oxygen, more preferably air.
51. The method of embodiment 49 or 50, wherein according to (c.4), calcining is performed in a gas atmosphere having a temperature in the range of from 350 to 500° C.
52. The method of embodiment 51, wherein the gas atmosphere comprises, preferably is, one or more of air, lean air, and oxygen, more preferably air.
53. The method of any one of embodiments 44 to 52, wherein y is in the range of from 20 to 80, preferably in the range of from 40 to 75, more preferably in the range of from 50 to 72, more preferably in the range of from 60 to 70.
54. The method of any one of embodiments 44 to 53, wherein disposing in one or more of (b), and (c), preferably disposing in (b) and (c), is performed by spraying the slurry onto the substrate or by immersing the substrate into the slurry, preferably by immersing the substrate into the slurry.
55. The method of any one of embodiments 44 to 54, consisting of (a), (b) and (c).
56. A catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, preferably a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx according to any one of embodiments 1 to 43, obtainable or obtained by a process according to any one of embodiments 44 to 55.
57. Use of a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx according to any one of embodiments 1 to 43 and 56 for the simultaneous selective catalytic reduction of NOx, the oxidation of ammonia and the oxidation of NO.
58. An exhaust gas treatment system for treating an exhaust gas stream exiting an internal combustion engine, preferably 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 a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx according to any one of embodiments 1 to 43 and 56 and one or more of a selective catalytic reduction catalyst, a combined selective catalytic reduction/ammonia oxidation catalyst, and a catalyzed soot filter.
59. The exhaust gas treatment system of embodiment 58, comprising the catalyst according to any one of embodiments 1 to 43 and 56 and a selective catalytic reduction catalyst, wherein the selective catalytic reduction catalyst is positioned upstream of the catalyst according to any one of embodiments 1 to 43 and 56, wherein the system preferably further comprises a first urea injector, the urea injector being positioned upstream of the selective catalytic reduction catalyst.
60. The exhaust gas treatment system of embodiment 58 or 59, further comprising a catalyzed soot filter, wherein the catalyzed soot filter is positioned downstream of the catalyst according to any one of embodiments 1 to 43 and 56.
61. The exhaust gas treatment system of any one of embodiments 58 to 60, further comprises a combined selective catalytic reduction/ammonia oxidation catalyst and a second selective catalytic reduction catalyst, wherein the combined selective catalytic reduction/ammonia oxidation catalyst is positioned downstream of the second selective catalytic reduction catalyst and the second catalytic reduction catalyst is positioned upstream of the combined selective catalytic reduction/ammonia oxidation catalyst and downstream of the catalyzed soot filter; wherein the system preferably further comprises a second urea injector, the second urea injector being positioned downstream of the catalyzed soot filter and upstream of the second selective catalytic reduction catalyst.
62. A method for the simultaneous selective catalytic reduction of NOx, the oxidation of ammonia and the oxidation of nitrogen monoxide, the method comprising
In the context of the present invention, the term “loading of a given component/coating” (in g/in3 or g/ft3) refers to the mass of said component/coating per volume of the substrate, wherein the volume of the substrate is the volume which is defined by the cross-section of the substrate times the axial length of the substrate over which said component/coating is present. For example, if reference is made to the loading of a first coating extending over x % of the axial length of the substrate and having a loading of X g/in3, said loading would refer to X gram of the first coating per x % of the volume (in in3) of the entire substrate.
Further, in the context of the present invention, a term “X is one or more of A, B and C”, wherein X is a given feature and each of A, B and C stands for specific realization of said feature, is to be understood as disclosing that X is either A, or B, or C, or A and B, or A and C, or B and C, or A and B and C. In this regard, it is noted that the skilled person is capable of transfer to above abstract term to a concrete example, e.g. where X is a chemical element and A, B and C are concrete elements such as Li, Na, and K, or X is a temperature and A, B and C are concrete temperatures such as 10° C., 20° C., and 30° C. In this regard, it is further noted that the skilled person is capable of extending the above term to less specific realizations of said feature, e.g. “X is one or more of A and B” disclosing that X is either A, or B, or A and B, or to more specific realizations of said feature, e.g. “X is one or more of A, B, C and D”, disclosing that X is either A, or B, or C, or D, or A and B, or A and C, or A and D, or B and C, or B and D, or C and D, or A and B and C, or A and B and D, or B and C and D, or A and B and C and D.
Furthermore, in the context of the present invention, the term “the surface of the internal walls” is to be understood as the “naked” or “bare” or “blank” surface of the walls, i.e. the surface of the walls in an untreated state which consists - apart from any unavoidable impurities with which the surface may be contaminated - of the material of the walls.
Furthermore, in the context of the present invention, the term “noble metals” encompasses metals which are ruthenium, rhodium, palladium, platinum, silver, osmium, iridium and gold.
In the context of the present invention, the term “consists of” with regard to the weight-% of one or more components indicates the weight-% amount of said component(s) based on 100 weight-% of the entity in question. For example, the wording “wherein from 0 to 0.001 weight-% of the first coating consists of platinum” indicates that among the 100 weight-% of the components of which said coating consists of, 0 to 0.001 weight-% is platinum.
The present invention is further illustrated by the following reference examples, comparative examples and examples.
The particle size distributions were determined by a static light scattering method using Sympatec HELOS equipment, wherein the optical concentration of the sample was in the range of from 5 to 10 %.
The BET specific surface area was determined according to DIN 66131 or DIN ISO 9277 using liquid nitrogen.
In order to coat the flow-through substrate with one or more coatings, the flow-through substrate was suitably immersed vertically in a portion of a given slurry for a specific length of the substrate which was equal to the targeted length of the coating to be applied. In this manner, the slurry contacted the walls of the substrate.
Third coating (outlet bottom coating):
To a Si-doped titania powder (10 weight-% of SiO2, a BET specific surface area of 200 m2/g and a Dv90 of 20 micrometers) was added a platinum ammine solution, such that the Si-titania had after calcination a Pt content of 0.81 weight-% based on the weight of Si-titania. This material was added to water and the slurry was milled until the resulting Dv90 was 5.2 microns, determined as described in Reference Example 1. Finally, a colloidal silica binder was mixed into the slurry at a level calculated to be 2.5 weight-% SiO2 (from the binder) after calcination based on the weight of Si-titania. The resulting mixture was then disposed from the outlet side of an uncoated honeycomb flow-through cordierite monolith substrate toward the inlet side over half of the length of the substrate using the coating method described in Reference Example 3 (diameter: 26.67 cm (10.5 inches) x 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) to form the third coating. Afterwards, the coated substrate was dried and then calcined in an oven. The loading of the third coating after calcination was about 1 g/in3, including a platinum loading in the third coating of 14 g/ft3.
Second coating (inlet bottom coating):
To a Si-doped titania powder (10 wt% SiO2, BET specific surface area of 200 m2/g, a Dv90 of 20 microns) was added a platinum ammine solution. After calcination at 590° C. the final Pt/Sititania had a Pt content of 0.46 weight-% based on the weight of Si-titania. This material was added to water and the slurry was milled until the resulting Dv90 was 10 microns, as described in Reference Example 1. To an aqueous slurry of Cu—CHA zeolitic material (5.1 weight-% CuO and a SiO2:Al2O3 molar ratio of 18) was added a zirconyl-acetate solution to achieve 5 weight-% ZrO2 after calcination based on the weight of the zeolitic material. To this Cu—CHA slurry, the Pt-containing slurry was added and stirred, creating the final slurry. The final slurry was then disposed over half the length of the honeycomb cordierite monolith substrate, coated with the third coating, from the inlet side of the substrate towards the outlet side, ensuring that the second coating does not overlap the third coating and using the coating method described in Reference Example 3 . Afterwards, the coated substrate was dried and then calcined in an oven. The loading of the second coating, after calcination, was about 2 g/in3 with a Cu—CHA loading of 1.67 g/in3, a ZrO2 loading of 0.08 g/in3, a Si-titania loading of 0.25 g/in3 and a PGM loading of 2 g/ft3. The weight ratio of the Si-titania to Cu—CHA is of about 0.15:1.
First coating (full-length top coating):
To an aqueous slurry of Cu—CHA zeolitic material (5.1 weight-% CuO and a SiO2:Al2O3 molar ratio of 18) was added a zirconyl-acetate solution to achieve 5 weight-% ZrO2 after calcination based on the weight of the zeolitic material. The slurry was then disposed over the full length of the honeycomb cordierite monolith substrate, coated with the third and second coatings, from the inlet side of the substrate towards the outlet side and covering the second and third coatings using the coating method described in Reference Example 3. Afterwards, the coated substrate was dried and then calcined in an oven. The loading of this first coating after calcination was 1.0 g/in3.
The final catalytic loading (1st, 2nd and 3rd coatings) in the catalyst after calcination was about 2.5 g/in3.
Second coating (outlet bottom coating):
An incipient wetness impregnation of Pt into a silica-doped titania powder (TiO2 (90 weight-%) and 10 weight-% of SiO2, having a BET specific surface area of 200 m2/g, a Dv90 of 20 micrometers, and a fresh pore volume of 0.6 cm3/g)was made. The Pt source was a suspension of colloidal stabilized Pt with a 2 weight-% solid content. The volume of the impregnating solution was calculated based on the mass of the titania powder and the corresponding pore volume. The Pt was then thermally fixated by powder calcining the impregnated silica-doped titania at 590° C. for 1 hour. After the thermal fixation, the impregnated silica-doped titania powder was reslurried with deionized water and tartaric acid such that the solid content of the final slurry was 40 weight-% and the pH of the aqueous phase of said slurry was 3.75. The slurry was then milled until the resulting Dv90 was 10 micrometers, determined as described in Reference Example 1.
Separately, a zeolite slurry was produced by mixing a Cu—CHA zeolite (5.1 weight-% of Cu, calculated as CuO, and a SiO2:Al2O3 molar ratio of 18) with deionized water, such that the resulting slurry solid content was 38 weight-%. This Cu—CHA slurry was then added to the Pt/silicadoped titania slurry. The weight ratio of Pt/silica-doped titania to Cu—CHA was of about 4:1. Lastly, a colloidal silica binder (with a solid content of 34.5 weight-%) and deionized water were added to the slurry to bring the final slurry solid content to 38 weight-%. The resulting mixture was then disposed from the outlet side of an uncoated honeycomb flow-through cordierite monolith substrate toward the inlet side over 67 % of the length of the substrate using the coating method described in Reference Example 3 (diameter: 26.67 cm (10.5 inches) x 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)to for the second coating. Afterwards, the coated substrate was dried and then calcined. The final loading of the second coating, after calcination, was 1.25 g/in3, including 0.24 g/in3 of Cu—CHA, 1 g/in3 of a silica-doped titania, and 0.012 g/in3 of SiO2 loading (binder). The PGM loading in the second coating (coated over 67 % of the substrate length) was 12 g/ft3. The ratio of the first loading (Pt/silica-doped titania), in g/l, to the second loading (Cu—CHA), in g/l, L1:L2, is of about 4:1.
First coating (full-length top coating)
An aqueous zirconyl acetate solution was diluted in water (3.1 weight% of ZrO2 in water). The amount of zirconyl acetate was calculated such that the loading of zirconia (in the first coating) after calcination, calculated as ZrO2, was 0.05 g/in3. To this, a Cu—CHA zeolite (5.1 weight-% of Cu, calculated as CuO, and a SiO2: Al2O3 molar ratio of 18) was added and mixed. The resulting slurry had a solid content of 38% by weight. This slurry was then disposed over the full length of the coated honeycomb cordierite monolith substrate, from the inlet side of the substrate towards the outlet side and covering the second coating using the coating method described in Reference Example 3. Afterwards, the coated substrate was dried and then calcined. The loading of the first coating, after calcination, was 2 g/in3, including 1.95 g/in3 of Cu—CHA and 0.05 g/in3 of ZrO2.
The final loading (1st and 2nd coatings) in the catalyst after calcination was about 2.85 g/in3.
The catalysts were evaluated on a motor test cell equipped with a 6.7 L off-road calibrated engine. In all cases, each catalyst was tested alone, without any upstream oxidation or downstream SCR catalysts. The resulting space velocity was 85 k/h for the SCR test (165 k/h for the highest temperature point). The SCR test used an ammonia to NOx ratio (ANR) sweep test with different stoichiometric ratios between NH3 and NOx. For the data presented in
As may be taken from
The catalysts were evaluated on a motor test cell equipped with a 6.7 L off-road calibrated engine. In all cases, each catalyst was tested alone, without any upstream oxidation or downstream SCR catalysts. The resulting space velocity was 100 k/h for the NOx oxidation test. Prior to this test, the catalysts were degreened in-situ, namely heated at 450° C. for 2 hours. The catalyst of Example 1 was also tested after ageing at 500° C. for 50 hours in hydrothermal oven with 10% H2O. For the NO oxidation test, the outlet exhaust temperature was increased and decreased step-wise from 200° C. to 500° C. to 200° C. in 25° C. steps while maintaining constant space velocity. Each step was held for 15 minutes to reach equilibrium catalyst conditions. NO oxidation activity is reported as the ratio of NO2 to total NOx (or NO2/NOx %). As may be taken from
| Number | Date | Country | Kind |
|---|---|---|---|
| 20168921.3 | Apr 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/059277 | 4/9/2021 | WO |
