Method for regenerating nitrogen oxide storage catalysts

Details Method for regenerating nitrogen oxide storage catalysts Method for regenerating nitrogen oxide storage catalysts

2011-03-15

2011-03-15

Denion, Thomas E (Department: 3748)

Power plants

Internal combustion engine with treatment or handling of...

By means producing a chemical reaction of a component of the...

C060S286000, C060S289000

Reexamination Certificate

active

07905087

ABSTRACT:
Nitrogen oxide storage catalytic converters for purifying the exhaust gas of lean-burn engines are periodically regenerated by switching the engine from lean-burn mode to rich-burn mode. After regeneration has taken place, the engine is switched back to lean-burn mode. At this time, rich exhaust gas is still flowing in the exhaust line from the engine to the catalytic converter, which rich exhaust gas is ejected via the catalytic converter into the environment by the following, lean exhaust gas. This leads to brief emissions peaks of the rich exhaust gas constituents and impairs the level of exhaust gas cleaning which can be obtained. In order to solve said problem, it is proposed to create oxidizing conditions by injecting air upstream of the storage catalytic converter, so that the rich exhaust gas constituents still flowing in the exhaust line upstream of the storage catalytic converter can be converted at the storage catalytic converter to form non-harmful products. The proposed method can lead to a considerable improvement in exhaust gas purification in particular in the case of catalytic converters which are already impaired in terms of their storage capacity through aging, and which must be regenerated significantly more frequently than fresh catalytic converters.

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