LNT regeneration strategy to reduce NOx spike

摘要

Systems and methods are disclosed for ameliorating NOx slip from a lean NOx trap by reducing the amount of hydrocarbons reaching the lean NOx trap during the early stages of, or in a period immediately preceding, a rich regeneration. In one embodiment, a hydrocarbon absorber is configured downstream from a fuel reformer, but upstream from the lean NOx trap, in order to reduce the quantity of hydrocarbons that reach the lean NOx trap during lean reformer warm-up and rich regeneration phases. In another embodiment, the fueling rate to a fuel reformer configured in an exhaust line upstream from the lean NOx trap is limited to reduce NOx slip.