Filter comprising combined soot oxidation and NH3-SCR catalyst

Patent metadata

Field	Value
Publication number	US-9283519-B2
Application number	US-201113384572-A
Country	US
Kind code	B2
Filing date	Feb 1, 2011
Priority date	Feb 1, 2010
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

A wall-flow filter for filtering particulate matter from a flowing exhaust gas comprises a catalyst for catalyzing both the conversion of solid carbon in the particulate matter by oxygen and the selective reduction of oxides of nitrogen in the exhaust gas with a nitrogenous reductant, which catalyst comprising optionally stabilized ceria and at least one metal selected from (i) tungsten and (ii) both tungsten and iron.

First claim

The invention claimed is:

1. A method of treating exhaust gas emissions from internal combustion engines and having oxides of nitrogen and soot, which method comprising passing the exhaust gas through a wall-flow filter in the presence of a nitrogenous reductant, which filter comprising a layer of catalyst coated on an inert filter substrate, and
catalysing soot combustion by oxygen and selective reduction of oxides of nitrogen,
the steps of catalyzing soot combustion by oxygen and selective reduction of oxides of nitrogen each consisting of contacting the exhaust gas to the layer of the catalyst,
the catalyst comprises ceria that is optionally stabilised and at least one metal selected from (i) tungsten and (ii) both tungsten and iron.

2. A method according to claim 1 further comprising injecting the nitrogenous reductant with an injector means into the exhaust gas, wherein the wall-flow filter is disposed downstream of the injector means.

3. A method according to claim 2 , wherein the catalyst has a total metal content from 5 to 15% by weight.

4. A method according to claim 2 , wherein the porosity of the wall-flow filter is from 30-80%.

5. A method according to claim 2 further comprising oxidising nitric oxide in the exhaust gas to nitrogen dioxide with an oxidation catalyst disposed upstream of the injector means.

6. A method according to claim 2 , wherein the ceria of the catalyst is stabilised with a ceria stabiliser and the ceria stabiliser is selected from the group consisting of zirconium, lanthanides and mixtures of any two or more thereof.

7. A method according to claim 6 , wherein the ceria stabiliser is a lanthanide selected from the group consisting of La, Nd, Pr, Gd, and mixtures of any two or more thereof.

8. A method according to claim 6 , wherein the ceria is stabilised with zirconia, and the catalyst has a weight ratio of zirconia:ceria greater than 0:1 and less than or equal to 9:1.

9. A method according to claim 8 , wherein the weight ratio of zirconia:ceria is 1:4 to 4:1.

10. A method according to claim 2 , wherein the catalyst further comprises alumina stabilised with a stabiliser selected from the group consisting of silicon, zirconium, barium, lanthanides and mixtures of any two or more thereof.

11. A method according to claim 10 , wherein the stabiliser is a lanthanide selected from the group consisting of La, Ce, Nd, Pr, Gd, and mixtures of any two or more thereof.

12. A method according to claim 1 , wherein the ceria is stabilised with a ceria stabiliser and the ceria stabiliser is selected from the group consisting of zirconium, lanthanides and mixtures of any two or more thereof.

13. A method according to claim 12 , wherein the ceria stabiliser is a lanthanide selected from the group consisting of La, Nd, Pr, Gd, and mixtures of any two or more thereof.

14. A method according to claim 1 , wherein the ceria is stabilised with zirconia, and the catalyst has a weight ratio of zirconia:ceria greater than 0:1 and less than or equal to 9:1.

15. A method according to claim 14 , wherein the weight ratio of zirconia:ceria is 1:4 to 4:1.

16. A method according to claim 1 , wherein the total metal content of the catalyst is from 5 to 15% by weight.

17. A method according to claim 1 , wherein the porosity of the wall-flow filter is from 30-80%.

18. A method according to claim 1 , wherein the catalyst further comprises alumina stabilised with a stabiliser selected from the group consisting of silicon, zirconium, barium, lanthanides and mixtures of any two or more thereof.

Assignees

• Collier Jillian Elaine
• Dotzel Ralf
• Laroze Sylvie Cécile
• Leppelt Rainer
• Millington Paul James
• Münch Jörg Werner
• Rajaram Raj Rao
• Schedel Hubert
• Johnson Matthey Plc

Inventors

• Collier Jillian Elaine
• Dotzel Ralf
• Laroze Sylvie Cécile
• Leppelt Rainer
• Millington Paul James
• Münch Jörg Werner
• Rajaram Raj Rao
• Schedel Hubert

Classifications

• C04B35/50

  based on rare-earth compounds {(non-oxide rare earth compounds C04B35/5156)} · CPC title

• B01D2258/01

  Engine exhaust gases · CPC title

• Y10S55/30

  Exhaust treatment · CPC title

• C04B2235/6021

  Extrusion moulding · CPC title

• B01J23/72

  Copper · CPC title