Abgasreinigungsvorrichtung für einen Verbrennungsmotor

摘要

An upstream catalyst and a downstream catalyst are arranged in series and are housed in a common casing disposed in an engine exhaust passage. The upstream catalyst including a NOx storage-reduction catalyst that adsorbs NOx contained in incoming exhaust gas when the air-fuel ratio of the incoming exhaust gas is lean, and releases and reduces the adsorbed NOx when the air-fuel ratio of the incoming exhaust gas becomes rich, and the downstream catalyst includes a three-way catalyst. The upstream catalyst has a higher oxidizing capability than the downstream catalyst, and the downstream catalyst has a higher reducing capability than the upstream catalyst. The upstream catalyst has a multi-layer structure including an upper layer and a lower layer, and is prepared such that the upper layer has a higher oxidizing capability than the lower layer, and the lower layer has a higher reducing capability than the upper layer.