Diesel oxidation catalyst and exhaust system

Patent metadata

Field	Value
Publication number	US-2018353902-A1
Application number	US-201816107113-A
Country	US
Kind code	A1
Filing date	Aug 21, 2018
Priority date	Jan 23, 2014
Publication date	Dec 13, 2018
Grant date	—

Abstract

An exhaust system for a diesel engine comprises an oxidation catalyst for treating an exhaust gas from the diesel engine and an emissions control device, wherein the oxidation catalyst comprises: a first washcoat zone for oxidizing carbon monoxide (CO) and hydrocarbons (HCs), wherein the first washcoat zone comprises a first platinum group metal (PGM), which is a combination of platinum and palladium, a first support material and a hydrocarbon adsorbent material, which is a zeolite, and wherein the first washcoat zone does not comprise rhodium and is substantially free of manganese or an oxide thereof; a second washcoat zone for oxidizing nitric oxide (NO), wherein the second washcoat zone comprises platinum (Pt) and manganese (Mn) disposed or supported on a second support material, wherein the second support material comprises a refractory metal oxide, wherein the refractory metal oxide is silica-alumina or an alumina doped with silica in a total amount of 0.5 to 45% by weight of the alumina, and wherein the second washcoat zone does not comprise a hydrocarbon adsorbent material, which is a zeolite; and a substrate having and inlet end and an outlet end, and wherein the second washcoat zone is disposed at an outlet end of the substrate, and the first washcoat zone disposed at an inlet end of the substrate; and wherein the emissions control device is a selective catalytic reduction (SCR) catalyst, a selective catalytic reduction filter catalyst, a diesel particulate filter (DPF), or a catalyzed soot filter (CSF).

First claim

1 . An exhaust system for a diesel engine, which comprises an oxidation catalyst for treating an exhaust gas from the diesel engine and an emissions control device, wherein the oxidation catalyst comprises: a first washcoat zone for oxidizing carbon monoxide (CO) and hydrocarbons (HCs), wherein the first washcoat zone comprises a first platinum group metal (PGM), which is a combination of platinum and palladium, a first support material and a hydrocarbon adsorbent material, which is a zeolite, and wherein the first washcoat zone does not comprise rhodium and is substantially free of manganese or an oxide thereof; a second washcoat zone for oxidizing nitric oxide (NO), wherein the second washcoat zone comprises platinum (Pt) and manganese (Mn) disposed or supported on a second support material, wherein the second support material comprises a refractory metal oxide, wherein the refractory metal oxide is silica-alumina or an alumina doped with silica in a total amount of 0.5 to 45% by weight of the alumina, and wherein the second washcoat zone does not comprise a hydrocarbon adsorbent material, which is a zeolite; and a substrate having and inlet end and an outlet end, and wherein the second washcoat zone is disposed at an outlet end of the substrate, and the first washcoat zone disposed at an inlet end of the substrate; and wherein the emissions control device is a selective catalytic reduction (SCR) catalyst, a selective catalytic reduction filter catalyst, a diesel particulate filter (DPF), or a catalyzed soot filter (CSF).

2 . The exhaust system according to claim 1 , wherein the alumina is doped with silica in a total amount of 4.5 to 15% by weight of the alumina.

3 . The exhaust system according to claim 1 , wherein the second washcoat zone comprises platinum (Pt) as the only platinum group metal.

4 . The exhaust system 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.

5 . The exhaust system according to claim 1 , wherein the second 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.

6 . The exhaust system according to claim 5 , wherein the second support material comprises alumina doped with silica.

7 . The exhaust system according to claim 1 , wherein the second washcoat zone does not comprise rhodium, an alkali metal and/or an alkaline earth metal.

8 . The exhaust system according to claim 1 , wherein the first washcoat zone further comprises a hydrocarbon absorbing zeolite.

9 . The exhaust system according to claim 8 , wherein the first washcoat zone comprises a total amount of 0.2 to 3.00 g in −3 of the hydrocarbon absorbing zeolite.

10 . The exhaust system according to claim 1 , wherein the first washcoat zone further comprises an alkaline earth metal.

11 . The exhaust system according to claim 1 , wherein the substrate is a flow-through substrate.

12 . A vehicle comprising a diesel engine and an exhaust system as defined in claim 1 .

Assignees

• Johnson Matthey Plc

Inventors

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

Classifications

• B01D53/72

  Organic compounds not provided for in groups B01D53/48 - B01D53/70, e.g. hydrocarbons · CPC title

• F01N3/28

  Construction of catalytic reactors · CPC title

• B01J23/34

  Manganese · CPC title

• B01J23/44

  Palladium · CPC title

• B01J23/58

  with alkali- or alkaline earth metals · CPC title