Exhaust gas post processing apparatus

An exhaust gas post processing apparatus of a gasoline vehicle may include a housing mounted on the exhaust pipe to receive the exhaust gas discharged from the engine and to exhaust the exhaust gas passed through rearward thereof, a front end honeycomb catalyst unit embedded in the housing to primarily purify the exhaust gas introduced into the housing through a front end portion of the housing, and a rear end honeycomb catalyst unit embedded in the housing to secondarily purify the exhaust gas via the front end honeycomb catalyst unit before flowing out to a rear end portion of the housing, wherein the front end honeycomb catalyst unit includes a powder type catalyst in which an iridium-ruthenium alloy is supported on an aluminum oxide support powder, and the rear end honeycomb catalyst unit includes three-way catalyst powder which is configured to remove carbon monoxide, nitrogen oxides, and hydrocarbons simultaneously.