Exhaust gas control apparatus for internal combustion engine

摘要

A converter ( 70 ) which houses a NOx storage/reduction catalyst is provided in an exhaust passage ( 2 ) of an engine ( 1 ). At a front half portion (inlet side portion) ( 7 a) of a carrier of the NOx storage/reduction catalyst in the converter ( 70 ), the amount of an oxygen storage component is made less than it is at a rear half portion (outlet side portion) ( 7 b) of the carrier, and a NOx storage capacity is made larger than it is at the rear half portion ( 7 b) of the carrier. As a result, unpurified NOx released from the front half portion ( 7 a) of the carrier at the beginning of a rich spike due to an₀₂ storage operation is able to be stored in the rear half portion ( 7 b) of the carrier, and so is not exhausted outside the catalyst Moreover, the amount of HC and CO components in the exhaust gas that are needlessly consumed by the ₀₂ storage operation without being used to purify NOx is reduced, making it possible to purify NOx efficiently.