Zeolite promoted silver based catalyst for NOx storage
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.
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.