Method and device for purification of exhaust gas from an internal combustion engine

摘要

Method using a NOx trap additive in engine fuel with an exhaust particle filter (7) subjected to periodic regeneration. When the particle filter is regenerated the engine fuel feed is alternated between lean and rich mixture phases, so that NO2 in the exhaust gases is absorbed by the additive during the lean mixture phase(s) and the carbon particles are oxidized by the NO2 during the rich mixture phase(s). - The procedure, for use on an IC engine (1) with an exhaust particle filter (7) subjected to periodic regeneration, employs an NOx trap additive in the engine fuel that becomes trapped within carbon particles. When the particle filter is regenerated the engine fuel feed is alternated between lean and rich mixture phases, so that NO2 in the exhaust gases is absorbed by the additive during the lean mixture phase(s) and the carbon particles are oxidized by the NO2 during the rich mixture phase(s). The additive contains a substance that is converted into a nitrate during the rich mixture phase(s), such as K2CO3 or BaCO3, or a mixture of K2CO3, cerium and zirconium.