| 摘要 |
An exhaust gas purifying apparatus is provided which includes a three way catalyst provided in an exhaust pipe of an internal combustion engine; and a NOx adsorption/reduction catalyst provided in the exhaust pipe to be located downstream of the three way catalyst. Nickel serving as a catalyst source is loaded on an alumina support layer of the NOx adsorption/reduction catalyst. When the engine operates with a fuel-rich air/fuel mixture at a relatively small air-fuel ratio, a reducing atmosphere is formed around the NOx catalyst, and the reaction to convert NiO into NiS occurs, thereby to consume H2S. As a result, consumption of SO2 proceeds, and the reaction to convert BaSO4 as an oxidized product of sulfur deposited on the NOx catalyst into BaCO3 as an NOx adsorbent is accelerated in an oxidizing atmosphere, thereby resuming the purifying capability of the NOx catalyst. |
