Gasoline engine with an exhaust system for combusting particulate matter

Patent metadata

Field	Value
Publication number	US-2017080388-A1
Application number	US-201615369036-A
Country	US
Kind code	A1
Filing date	Dec 5, 2016
Priority date	Aug 1, 2001
Publication date	Mar 23, 2017
Grant date	—

Abstract

A gasoline engine having an exhaust system comprises means for trapping particulate matter (PM) from the exhaust gas and a catalyst for catalysing the oxidation of the PM by carbon dioxide and/or water in the exhaust gas, which catalyst comprising a supported alkali metal. The invention further includes a method of combusting PM from a gasoline engine in CO 2 and/or H 2 O from the exhaust gas at temperatures in excess of 500° C., which method comprising trapping the PM and contacting it with a catalyst comprising a supported alkali metal.

First claim

1 . A system comprising a three way catalyst (TWC) adapted for simultaneously oxidizing CO and HC and reducing NOx of an exhaust gas from a gasoline engine, means for trapping particulate matter (PM) of <100 nm from the exhaust gas and a catalyst for catalysing the oxidation of the PM by at least one of carbon dioxide (CO 2 ) and water (H 2 O) in the exhaust gas, which catalyst consists of a supported alkali metal, wherein the supported alkali metal is disposed downstream of the TWC and is disposed relative to the means for trapping in order to effect contact between the supported alkali metal and the particulate matter.

2 . A system according to claim 1 , wherein the alkali metal is selected from the group consisting of lithium, sodium, potassium, rubidium, caesium and a mixture of any two or more thereof

3 . A system according to claim 2 , wherein the alkali metal is the mixture and the mixture is a eutectic mixture.

4 . A system according to claim 1 , wherein the alkali metal is present in the catalyst at from 1% to 20% by weight of the catalyst.

5 . A system according to claim 1 , wherein the support is selected from the group consisting of alumina, ceria, zirconia, titania, a silica-alumina, a zeolite, a mixture thereof and a mixed oxide of any two or more thereof.

6 . A system according to claim 1 , wherein the support alumina selected from the group consisting of alpha-alumina, theta-alumina, gamma-alumina and a mixture of any two more thereof.

7 . A system according to claim 1 , wherein the alkali metal is potassium and the support is selected from the group consisting of alpha-alumina, zirconia, ceria and a mixture of any two or more thereof.

8 . A system according to claim 5 , wherein the support comprises the mixed oxide and each component of the mixed oxide is present in an amount of from 10 wt % to 90 wt % by total catalyst weight.

9 . A system according to claim 8 , wherein the mixed oxide is a binary mixed oxide and the ratio of the cationic components present is in a ratio of from 20:80 to 50:50.

10 . A system according to claim 1 , wherein the trapping means comprises a filter.

11 . A system according to claim 10 , wherein the filter comprises a wall-flow filter, a foam or a wire mesh.

12 . A system according to claim 11 , wherein the fitter is the foam and the foam is a metal oxide.

13 . A system according to claim 1 , wherein the trapping means is coated, at least in part, with the catalyst.

14 . A method of combusting PM of <100 nm comprising contacting an exhaust gas from a gasoline engine with a three-way catalyst adapted for simultaneously oxidizing CO and HC and reducing NOx of the exhaust gas, trapping the PM and contacting the trapped PM with a catalyst consisting of a supported alkali metal, said catalyst adapted to oxidize the PM by at least one of carbon dioxide (CO 2 ) and water (H 2 O) at temperatures in excess of 500° C.

15 . A method according to claim 14 , wherein the trapping step by electrophoresis or filtration.

16 . A system according to claim 1 , wherein the support is a mixed oxide of any two or more selected from the group consisting of alpha-alumina, zirconia and ceria.

17 . A system according to 16, wherein each component of the mixed oxide is present in an amount of from 10 wt % to 90 wt % by total catalyst weight.

18 . A system according to claim 12 , wherein the metal oxide is selected from the group consisting of alpha Al 2 O 3 , ZrO 2 /MgO, ZrO 2 /CaO/MgO and ZrO 2 /Al 2 O 3 .

19 . A system according to claim 1 , wherein the elemental alkali metal is present in the catalyst at from 5% to 15% by weight of the catalyst.

20 . A method according to claim 14 , wherein said catalyst is adapted to oxidize the PM at temperatures in excess of 550° C.

Assignees

• Johnson Matthey Plc

Inventors

• Mcnamara John Martin
• Rowe Julia Margaret
• Poulston Stephen
• Rajaram Raj Rao
• Crane Robert Ian
• Arcoumanis Constantine
• Rubino Lauretta

Classifications

• B01J21/066

  Zirconium or hafnium; Oxides or hydroxides thereof · CPC title

• B01D2255/2065

  Cerium · CPC title

• B01J23/10

  of rare earths · CPC title

• B01D2255/2092

  Aluminium · CPC title

• B01D2255/40

  Mixed oxides · CPC title