Diesel oxidation catalyst and exhaust system

Patent metadata

Field	Value
Publication number	US-11167246-B2
Application number	US-201816108279-A
Country	US
Kind code	B2
Filing date	Aug 22, 2018
Priority date	Jan 23, 2014
Publication date	Nov 9, 2021
Grant date	Nov 9, 2021

Abstract

An oxidation catalyst for treating an exhaust gas from a diesel engine comprises: a first washcoat region for oxidising carbon monoxide (CO) and hydrocarbons (HCs), wherein the first washcoat region comprises a first platinum group metal (PGM) and a first support material, and wherein the first washcoat region does not comprise manganese or an oxide thereof; a second washcoat region for oxidising nitric oxide (NO), wherein the second washcoat region comprises platinum (Pt), manganese (Mn) and a second support material comprising a refractory metal oxide, which is silica-alumina or alumina doped with silica in a total amount of 0.5 to 45% by weight of the alumina, wherein the platinum (Pt) is disposed or supported on the second support material and the manganese (Mn) is disposed or supported on the second support material; and a substrate having an inlet end and an outlet end, and wherein the first washcoat region is a first washcoat layer and the second washcoat region is a second washcoat layer, and the second washcoat layer is disposed on the first washcoat layer; and wherein when the oxidation catalyst comprises a hydrocarbon adsorbent, which is a zeolite, then the first washcoat region further comprises the hydrocarbon adsorbent.

First claim

The invention claimed is:

1. An oxidation catalyst for treating an exhaust gas from a diesel engine, which oxidation catalyst comprises:
a first washcoat region for oxidising carbon monoxide (CO) and hydrocarbons (HCs), wherein the first washcoat region comprises a first platinum group metal (PGM) and a first support material, and wherein the first washcoat region does not comprise manganese or an oxide thereof;
a second washcoat region for oxidising nitric oxide (NO), wherein the second washcoat region comprises platinum (Pt), manganese (Mn) and a second support material comprising a refractory metal oxide, which is an alumina doped with silica in a total amount of 0.5 to 45% by weight of the alumina, wherein the platinum (Pt) is disposed or supported on the second support material and the manganese (Mn) is disposed or supported on the second support material;
a third washcoat region comprising a zeolite catalyst, wherein the zeolite catalyst comprises Pd, a zeolite and optionally a base metal;
a substrate having an inlet end and an outlet end, and
wherein the first washcoat region is a first washcoat layer and the second washcoat region is a second washcoat layer, and the second washcoat layer is disposed on the first washcoat layer;
wherein the third washcoat region is disclosed directly on to the substrate; and
wherein the first washcoat region further comprises a hydrocarbon adsorbent which is a zeolite.

2. An oxidation catalyst according to claim 1 , wherein the second washcoat region comprises platinum (Pt) as the only platinum group metal.

3. An oxidation catalyst according to claim 1 , wherein the second washcoat region further comprises palladium (Pd), and has a ratio of platinum to palladium by total weight of ≥2:1.

4. An oxidation catalyst according to claim 1 , wherein the second washcoat region does not comprise rhodium, an alkali metal and/or an alkaline earth metal.

5. An oxidation catalyst according to claim 1 , wherein the second washcoat region is substantially free of a zeolite.

6. An oxidation catalyst according to claim 1 , wherein the first platinum group metal (PGM) is selected from the group consisting of platinum (Pt), palladium (Pd) and a combination thereof.

7. An oxidation catalyst according to claim 1 , wherein the first support material comprises a refractory metal oxide selected from the group consisting of alumina, silica, titania, zirconia, ceria and a mixed or composite oxide of two or more thereof.

8. An oxidation catalyst according to claim 7 , wherein the first support material comprises alumina doped with a dopant.

9. An oxidation catalyst according to claim 8 , wherein the first support material comprises alumina doped with silica.

10. An oxidation catalyst according to claim 1 , wherein the first washcoat region further comprises an alkaline earth metal.

11. An oxidation catalyst according to claim 1 , wherein the first washcoat region is disposed directly on to the substrate.

12. An oxidation catalyst for treating an exhaust gas from a diesel engine, which oxidation catalyst comprises:
a first washcoat region for oxidising carbon monoxide (CO) and hydrocarbons (HCs), wherein the first washcoat region comprises a first platinum group metal (PGM) and a first support material, and wherein the first washcoat region does not comprise manganese or an oxide thereof;
a second washcoat region for oxidising nitric oxide (NO), wherein the second washcoat region comprises platinum (Pt), manganese (Mn) and a second support material comprising a refractory metal oxide, which is an alumina doped with silica in a total amount of 0.5 to 45% by weight of the alumina, wherein the platinum (Pt) is disposed or supported on the second support material and the manganese (Mn) is disposed or supported on the second support material;
a third washcoat region disposed on the second washcoat region; and
a substrate having an inlet end and an outlet end,
wherein the first washcoat region is a first washcoat layer and the second washcoat region is a second washcoat layer, and the second washcoat layer is disposed on the first washcoat layer;
wherein the third washcoat region comprises a zeolite catalyst, wherein the zeolite catalyst comprises Pd, a zeolite and optionally a base metal; and
wherein the first washcoat region further comprises a hydrocarbon adsorbent which is a zeolite.

13. An oxidation catalyst according to claim 12 , wherein the substrate is a flow-through substrate.

14. An exhaust system comprising an oxidation catalyst as defined in claim 12 and an emissions control device.

15. An exhaust system according to claim 14 , wherein the emissions control device is selected from the group consisting of emissions control device selected from the group consisting of a lean NO, trap (LNT), an ammonia slip catalyst (ASC), diesel particulate filter (DPF), a selective catalytic reduction (SCR) catalyst, a catalysed soot filter (CSF), a selective catalytic reduction filter catalyst, and combinations of two or more thereof.

16. An oxidation catalyst according to claim 12 , wherein the second washcoat region comprises platinum (Pt) as the only platinum group metal.

17. An oxidation catalyst according to claim 12 , wherein the second washcoat region further comprises palladium (Pd), and has a ratio of platinum to palladium by total weight of ≥2:1.

18. An oxidation catalyst according to claim 12 , wherein the second washcoat region does not comprise rhodium, an alkali metal and/or an alkaline earth metal.

19. An oxidation catalyst according to claim 12 , wherein the second washcoat region is substantially free of a zeolite.

20. An oxidation catalyst according to claim 12 , wherein the first platinum group metal (PGM) is selected from the group consisting of platinum (Pt), palladium (Pd) and a combination thereof.

21. An oxidation catalyst according to claim 12 , wherein the first support material comprises a refractory metal oxide selected from the group consisting of alumina, silica, titania, zirconia, ceria and a mixed or composite oxide of two or more thereof.

22. An oxidation catalyst according to claim 21 , wherein the first support material comprises alumina doped with a dopant.

23. An oxidation catalyst according to claim 22 , wherein the first support material comprises alumina doped with silica.

24. An oxidation catalyst according to claim 12 , wherein the first washcoat region further comprises an alkaline earth metal.

25. An oxidation catalyst according to claim 12 , wherein the first washcoat region is disposed directly on to the substrate.

Assignees

• Johnson Matthey Plc

Inventors

• Chiffey Andrew Francis
• Goodwin John Benjamin
• Leeland James
• Moreau Francois

Classifications

• B01J35/56

  Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional [3D] monoliths · CPC title

• B01J37/02

  Impregnation, coating or precipitation ({B01J37/0009 and B01J37/0018 take precedence } ; protection by coating B01J33/00) · CPC title

• B01D2255/40

  Mixed oxides · CPC title

• F01N3/103

  Oxidation catalysts for HC and CO only · CPC title

• B01D2255/9022

  Two layers · CPC title