| abstract |
An exhaust system, and a catalyzed substrate, is disclosed. The system comprises a catalyzed substrate, a counterflow urea injector downstream of the catalyzed substrate, and a first selective catalytic reduction (SCR) catalyst downstream of the counterflow injector. The catalyzed substrate has an inlet end, an outlet end, an axial length extending from the inlet to the outlet, an inlet zone extending from the inlet, and an outlet zone extending from the outlet. The inlet zone comprises an oxidation catalyst and the outlet zone comprises a catalyst selected from the group consisting of a urea hydrolysis catalyst and a second SCR catalyst. The counterflow urea injector directs urea toward the outlet zone of the catalyzed substrate so that at least a portion of the urea contacts the outlet zone prior to contacting the first SCR catalyst. |