EXHAUST EMISSION CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

An exhaust purification system of an internal combustion engine comprising an NO X holding material arranged in an engine exhaust passage, having a catalyst metal containing silver, holding NO X contained in the exhaust gas in the form of silver nitrate by the catalyst metal when an air-fuel ratio of inflowing exhaust gas is lean, and releasing the held NO X if the air-fuel ratio of the inflowing exhaust gas becomes a stoichiometric air-fuel ratio or rich. The NO X holding material has a scatter temperature at which catalyst metal scatters in the form of silver nitrate if the temperature rises. When it is time to perform control raising the temperature of the NO X holding material to the scatter temperature or above, the NO X held in the NO X holding material is released by making the air-fuel ratio of the exhaust gas flowing into the NO X holding material the stoichiometric air-fuel ratio or rich.