Exhaust gas purifcation apparatus of internal combustion engine and catalyst for purifying exhaust gas of internal combustion engine

摘要

An exhaust gas purification apparatus for use in an internal combustion engine comprises an exhaust gas duct connected to the engine through which exhaust gas containing NO_x gas passes, and a catalyst disposed in the exhaust gas duct such that it contacts the exhaust gas. The catalyst chemically adsorbs NO_x when a stoichiometric amount of a gaseous oxidizing agent present in the exhaust gas is larger than that of a gaseous reducing agent present in the exhaust gas for reducing NO_x, adsorbed NO_x is catalytically reduced in the presence of a reducing agent when the stoichiometric amount of the oxidizing agent is not larger that of the reducing agent.