Reduction of particulate, NOx, and ammonia emissions

摘要

A method for controlling emissions from an engine includes reducing trapped nitrogen oxides to ammonia on an LNT catalyst while concurrently oxidizing soot accumulated on the LNT catalyst, and, flowing the ammonia so formed to an SCR catalyst.

主权项

1. A method for controlling emissions from an engine, comprising:
reducing trapped nitrogen oxides to ammonia on a lean nitrogen-oxide trapping (LNT) catalyst while concurrently oxidizing soot accumulated on the LNT catalyst including flowing exhaust from the engine over the LNT catalyst; flowing the ammonia to a selective catalytic reduction (SCR) catalyst; and adjusting a duration of flowing the exhaust over the LNT catalyst in response to an amount of soot oxidized on the LNT catalyst.