摘要 |
Emissions treatment systems and methods are disclosed, which reduce the carbon monoxide, unburned hydrocarbons, and nitrogen oxides content in the exhaust stream of an internal combustion engine adjusted to a rich combustion ratio. One embodiment of a system comprises an ammonia oxidation catalyst, a supplemental air supply for providing a lean combustion ratio, and at least one three-way catalyst. Another embodiment further comprises a second three-way catalyst located in the exhaust stream. |