EXHAUST EMISSION CONTROL CATALYST DEVICE AND EXHAUST EMISSION CONTROL METHOD

摘要

PROBLEM TO BE SOLVED: To improve NOx purification performance in a prescribed time after switching to SI combustion mode from HCCI combustion mode where NOx is hardly generated in an exhaust emission control catalyst device including a three-way catalyst and an oxidation catalyst.SOLUTION: In the exhaust emission control catalyst device 27 including a first catalyst 41 and a second catalyst 42, an NOx trap material 71 free from a catalyst metal is disposed upstream relative to the first catalyst 41.SELECTED DRAWING: Figure 1