Exhaust purification device of internal combustion engine

摘要

An SOX trap catalyst 12 and NOX purification catalyst 13 are arranged in an engine exhaust passage. A substrate 50 of the NOX purification catalyst 13 is formed with a coat layer comprised of at least the two layers of an upper coat layer 51 and a lower coat layer 52. The lower coat layer 52 is formed from an NOX storage catalyst storing the NOX contained in the exhaust gas when the air-fuel ratio of the exhaust gas is lean and releasing the stored NOX when the air-fuel ratio of the exhaust gas is a stoichiometric air-fuel ratio or rich. The upper coat layer 51 is formed from a material of a weaker basicity than this NOX storage catalyst.