Exhaust gas purifying apparatus and method thereof

摘要

An exhaust gas purifying apparatus provided in an exhaust passage connected with an engine includes an upstream catalyst that is provided in the exhaust passage, and that removes NOx; a downstream catalyst that is provided downstream of the upstream catalyst in the exhaust passage; and a supply device that supplies an oxygen-activating component to a portion of the exhaust passage located between the upstream catalyst and the downstream catalyst. In the exhaust gas purifying apparatus, the upstream catalyst removes NOx, and then an oxygen-activating component is supplied to the exhaust gas. Further, the downstream catalyst removes a hydrocarbon compound contained in the exhaust gas.