SYSTEM AND PROCESS FOR PURIFYING EXHAUST GAS

摘要

PURPOSE: To purify effectively HC exhausted at the time of cool starting of an engine by disposing a low temperature ignitable catalyst composition containing a substance provided with the electron donative properties and/or absorbing and discharging actions of nitrogen dioxide and a precious stone and an adsorption material provided with hydrocarbon adsorption power in an exhaust pipe of an internal combustion engine. CONSTITUTION: A low temperature ignitable catalyst composition 21 carrying a catalyst layer containing a substance provided with electron donative properties and/or absorbing and discharging actions of nitrogen dioxide and a noble metal on a carrier is disposed on the upstream side of an exhaust gas flow path from an engine 13. Also an adsorption body 31 carrying an adsorption layer provided with hydrocarbon power on a carrier is disposed on the vulcanizing side. An A/F adjusting O2 sensor 17 is set on the upstream side and a secondary air introduction opening 19 for accelerating ignition is formed on the downstream side between the engine 13 and the adsorption body 31, and a catalyst 29 is set on a position on the engine manifold outlet side. HC generated in a large amount at the tie of cold starting of the engine can be purified effectively by the arrangement.