초록 ▼

A process and an assembly for eliminating nitrogen oxides (NO.sub.x) present in the exhaust gas of a lean-burn diesel or spark-ignition engine, is part of the exhaust line coming from the engine. At least one nitrogen oxides conversion catalyst is placed in the main exhaust line the catalysts having

A process and an assembly for eliminating nitrogen oxides (NO.sub.x) present in the exhaust gas of a lean-burn diesel or spark-ignition engine, is part of the exhaust line coming from the engine. At least one nitrogen oxides conversion catalyst is placed in the main exhaust line the catalysts having non-coinciding temperature ranges for which the NO.sub.x conversion is below a certain conversion coefficient (C.sub.min). At least one NO.sub.x trap placed upstream is the conversion catalyst(s) and intended to trap, then to release the nitrogen oxides. At least one line bypassing the main exhaust line contains at least one of the NO.sub.x trap(s); and at least one valve intended to modulate the flow of gas between the bypass line and the main exhaust line is provided so that the NO.sub.x trap(s) can trap the nitrogen oxides, notably when conversion catalyst(s) have a conversion coefficient below a predetermined value (C.sub.min) and so that said the NO.sub.x trap(s) means (4) can release the nitrogen oxides simultaneously with a conversion.

대표청구항 ▼

[ We claim:] [1.] An assembly for elimination of nitrogen oxides (NO.sub.x) present in exhaust gas of a lean-burn diesel or spark-ignition engine, said assembly being part of a main exhaust line coming from the engine and comprising:a plurality of nitrogen oxides conversion catalysts placed in said

[ We claim:] [1.] An assembly for elimination of nitrogen oxides (NO.sub.x) present in exhaust gas of a lean-burn diesel or spark-ignition engine, said assembly being part of a main exhaust line coming from the engine and comprising:a plurality of nitrogen oxides conversion catalysts placed in said main exhaust line, said conversion catalysts having non-coinciding temperature ranges for which the NO.sub.x, conversion is below a certain conversion coefficient (C.sub.min),at least one NO.sub.x trapping means placed upstream from said conversion catalysts for trapping, then releasing nitrogen oxides,at least one bypass bypassing said main exhaust line and containing said at least one NO.sub.x trapping means,at least one valve to modulate the flow of gas between said bypass line and said main exhaust line so that said at least one NO.sub.x trapping means can trap said nitrogen oxides notably when said conversion catalysts have a conversion coefficient below said predetermined value (C.sub.min) and so that said at least one NO.sub.x trapping means can release said nitrogen oxides simultaneously with a conversion.