Patent ID: 7891175
Filing Date: 2011-02-22
Classification: B01D,F01N,F02D,Y02A

Abstract:
1. An exhaust purification device of a compression ignition type internal combustion engine, comprising: an SO x trap catalyst arranged in an engine exhaust passage for trapping SO x contained in an exhaust gas and an NO x storing catalyst arranged in the exhaust passage downstream of the SO x trap catalyst for storing NO x contained in the exhaust gas when an air-fuel ratio of an inflowing exhaust gas is lean and releasing stored NO x when the air-fuel ratio of the inflowing exhaust gas becomes a stoichiometric air-fuel ratio or rich, wherein the SO x trap catalyst is strengthened in basicity and is weakened in oxidizability compared with the NO x storing catalyst to an extent so that when a temperature of the SO x trap catalyst is substantially 150° C. to substantially 400° C., the NO x purification rate by the SO x trap catalyst becomes less than substantially 10 percent of the NO x purification rate by the NO x storing catalyst, and, when NO x should be released from the NO x storing catalyst, the air-fuel ratio of the exhaust gas flowing into the SO x trap catalyst is temporarily switched from lean to rich.