Exhaust system with a modified lean NOx trap
AssigneeJohnson Matthey Public Limited Company
InventorDaniel Swallow
Life of this patent
Estimating the term…
Abstract
An exhaust system for treating an exhaust gas from an internal combustion engine is disclosed. The system comprises a modified lean NOx trap (LNT), a urea injection system, and an ammonia-selective catalytic reduction (NH3-SCR) catalyst. The modified LNT comprises platinum, palladium, barium, and a ceria-containing material, and has a platinum:palladium molar ratio of at least 3:1. The modified LNT stores NOx at temperatures below about 200° C. and releases the stored NOx at temperatures above about 200° C. The urea injection system injects urea at temperatures above about 180° C.
Claims9
An exhaust system for treating an exhaust gas from an internal combustion engine, comprising:
- (a) NOx treatment catalysts, and
- (b) a urea injection system;
- wherein the NOx treatment catalysts consist essentially of a single layer lean NOx trap (LNT), comprising platinum, palladium, barium, and a ceria-containing material and a platinum:palladium molar ratio of at least 3:1;
- and an ammonia-selective catalytic reduction (NH3-SCR) catalyst;
- wherein the urea injection system is upstream of the NH3-SCR catalyst and downstream of the LNT;
- and
- wherein the LNT stores NOx at temperatures below about 200° C. and releases the stored NOx at temperatures above about 200° C.
Dependencies are inferred from the claim text.