Automotive catalytic aftertreatment system

Patent metadata

Field	Value
Publication number	US-9341098-B2
Application number	US-201213713349-A
Country	US
Kind code	B2
Filing date	Dec 13, 2012
Priority date	Dec 14, 2011
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

A catalytic aftertreatment system for a diesel engine exhaust gas is described. The system comprises a diesel oxidation catalyst (DOC) and an aftertreatment device located downstream of the diesel oxidation catalyst (DOC), which aftertreatment device requires periodic heat treatment, and means to generate a temperature increase within the aftertreatment device, said diesel oxidation catalyst (DOC) comprising an upstream zone of length from 0.5 to 2 inches (12.7-50.81 mm) of higher oxidation activity for hydrocarbons (HC) than the remainder of the diesel oxidation catalyst (DOC).

First claim

The invention claimed is:

1. A catalytic aftertreatment system for a diesel engine exhaust gas, said system comprising a diesel oxidation catalyst (DOC) and an aftertreatment device located downstream of the diesel oxidation catalyst (DOC), which aftertreatment device requires periodic heat treatment, and means to generate a temperature increase within the aftertreatment device, said diesel oxidation catalyst (DOC) having a diameter of from 4 to 15 inches and a length of from 2.5 to 10 inches, said diesel oxidation catalyst (DOC) comprising:
a catalyst composition supported on a substrate unit, wherein the catalyst composition comprises platinum, palladium and one or more support materials selected from the group consisting of alumina, silica, alumina, cerium, ceria-zirconia and titania and does not include a hydrocarbon adsorbent;
an upstream zone of the catalyst composition and a remainder;
wherein the upstream zone has a concentration of platinum (Pt) that is greater than the concentration of platinum (Pt) in the remainder; and
wherein the upstream zone has a length of 0.5 to 1.5 inches (12.7-38.1 mm), and is of higher oxidation activity for hydrocarbons (HC) than the remainder; and
the weight ratio of platinum (Pt) to palladium (Pd) in the remainder is 1:3 to 5:1.

2. The catalytic aftertreatment system according to claim 1 wherein the diesel oxidation catalyst comprises a mixture of platinum (Pt) and palladium (Pd), or an alloy of platinum (Pt) and palladium (Pd).

3. The catalytic aftertreatment system according to claim 1 , wherein the platinum group metal (PGM) concentration of the upstream zone is from 10 to 150 g ft −3 .

4. The catalytic aftertreatment system according to claim 1 , wherein the aftertreatment device is a soot filter.

5. The catalytic aftertreatment system according to claim 1 , wherein the aftertreatment device is a catalyst unit for selective catalytic reduction (SCR).

6. The catalytic aftertreatment system according to claim 1 , further comprising a heavy duty diesel engine.

7. The catalytic aftertreatment system according to claim 1 , wherein the concentration of palladium (Pd) in the upstream zone is less than the concentration of palladium (Pd) in the remainder.

8. The catalytic aftertreatment system according to claim 1 , wherein the remainder of the diesel oxidation catalyst (DOC) comprises a plurality of zones.

9. The catalytic aftertreatment system according to claim 1 , wherein the remainder of the diesel oxidation catalyst (DOC) comprises a plurality of layers.

10. A vehicle comprising a diesel engine and a catalytic aftertreatment system according to claim 1 .

Assignees

• Johnson Matthey Plc
• Johnson Matthey Plc

Inventors

• Cole Kieran
• Newman Colin
• Tingay Isabel
• Sonntag Olivier
• Smedler Gudmund
• Savage Ruth

Classifications

• B01J23/44

  Palladium · CPC title

• F01N3/103

  Oxidation catalysts for HC and CO only · CPC title

• B01D2258/012

  Diesel engines and lean burn gasoline engines · CPC title

• F01N3/2066

  Selective catalytic reduction [SCR] · CPC title

• B01D53/94 Primary

  by catalytic processes · CPC title