Zeolite promoted silver based catalyst for NOx storage

Patent metadata

Field	Value
Publication number	US-9597635-B2
Application number	US-201414559983-A
Country	US
Kind code	B2
Filing date	Dec 4, 2014
Priority date	Dec 4, 2014
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

An aftertreatment system utilizes chemical reactions to treat an exhaust gas flow. A device for use within an aftertreatment system includes a silver-based NOx storage catalyst and a zeolite. The silver-based NOx storage catalyst and the zeolite store NOx through a low temperature startup period of operation. In one embodiment, the zeolite includes a barium Y zeolite.

First claim

The invention claimed is:

1. A device for aftertreatment of an exhaust gas flow, the device comprising:
a silver-based NOx storage catalyst; and
a zeolite;
wherein the zeolite is dispersed as a separate layer from the silver-based NOx storage catalyst;
wherein the silver-based NOx storage catalyst and the zeolite store NOx through a low temperature startup period of exhaust gas flow; and
wherein the device comprises:
a first zone comprising the silver-based NOx storage catalysts and the zeolite configured to provide hydrogen-assisted conversion of NO to NO 2 ; and
a second zone located downstream of the first zone and comprising a platinum-group metal catalyst.

2. The device of claim 1 , wherein the device is located upstream of a second device configured to treat the NOx once released.

3. The device of claim 2 , wherein the second device comprises a selective catalytic reduction device.

4. The device of claim 2 , wherein the second device comprises a lean NOx trap device.

5. The device of claim 1 , wherein the device is located upstream of a platinum-group metal catalyst device configured to oxidize carbon monoxide, hydrocarbons, and NO to NO 2 .

6. The device of claim 1 , wherein the zeolite comprises barium Y zeolite.

7. The device of claim 6 , wherein the barium Y zeolite is utilized with a total washcoat loading of between 30 grams per Liter and 150 grams per Liter.

8. The device of claim 6 , wherein the barium Y zeolite is utilized with a total washcoat loading of 100 grams per Liter.

9. The device of claim 1 , wherein the zeolite comprises a base zeolite selected from the group consisting of Y zeolite, beta zeolite, ZSM-5, SSZ-13, and SAPO-34.

10. The device of claim 1 , wherein the zeolite comprises a base metal selected from the group consisting of copper, iron, silver, and barium.

11. The device of claim 1 , wherein the zeolite is dispersed as a separate layer on top of the silver-based NOx storage catalyst.

12. The device of claim 1 , wherein the zeolite is dispersed as a separate layer under the silver-based NOx storage catalyst.

13. The device of claim 1 , wherein the silver-based NOx storage catalyst comprises a Ag 2 O/Al 2 O 3 catalyst.

14. The device of claim 13 , wherein the Ag 2 O/Al 2 O 3 catalyst is utilized with a total washcoat loading of between 50 grams per Liter and 200 grams per Liter.

15. The device of claim 13 , wherein the Ag 2 O/Al 2 O 3 catalyst is utilized with a total washcoat loading of 170 grams per Liter.

16. A device for aftertreatment of an exhaust gas flow, the device comprising:
a NOx storage catalyst comprising:
a silver-based NOx storage catalyst; and
a barium Y zeolite;

wherein the barium Y zeolite is dispersed as a separate layer from the silver-based NOx storage catalyst and the silver-based NOx storage catalyst and the barium Y zeolite store NOx through a low temperature startup period of exhaust gas flow and are configured to provide hydrogen-assisted conversion of NO to NO 2 ; and
wherein the device comprises:
a first zone comprising the silver-based NOx storage catalysts and the barium Y zeolite configured to provide hydrogen-assisted conversion of NO to NO 2 ; and
a second zone located downstream of the first zone and comprising a platinum-group metal catalyst.

17. The device of claim 16 , wherein the silver-based NOx storage catalyst comprises a Ag 2 O/Al 2 O 3 catalyst utilized with a total washcoat loading of between 50 grams per Liter and 200 grams per Liter; and
wherein the barium Y zeolite is utilized with a total washcoat loading of between 30 grams per Liter and 150 grams per Liter.

18. The device of claim 16 , wherein the silver-based NOx storage catalyst comprises a Ag 2 O/Al 2 O 3 catalyst utilized with a total washcoat loading of 170 grams per Liter; and
wherein the barium Y zeolite is utilized with a total washcoat loading of between 100 grams per Liter.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Qi Gongshin
• Schmieg Steven J
• Ren Shouxian
• Li Wei

Classifications

• B01J29/126 Primary

  Y-type faujasite · CPC title

• B01J35/56

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

• F01N3/021

  by means of filters · CPC title

• B01D2255/9032

  Two zones · CPC title

• B01D2255/102

  Platinum group metals · CPC title