A PART OF MARELLI
The exhaust system must integrate the catalytic converter in order to convert the pollutants present in the exhaust gas with the highest efficiency. A catalytic converter consists of a ceramic or metallic monolith which is coated by a catalyst. The ceramic substrate is protected against vibrations and thermal shocks by a flexible ceramic mat which completely envelops the monolith: the entire unit is contained in a metal housing. The metal-type substrate, on the other hand, is brazed directly on the housing.
The catalyst is mainly composed of promoter and high surface area oxides, on which the catalytically active metals are supported. The set of these components is capable of converting CO, HC and NOx in gasoline systems, and CO and HC in diesel systems, to carbon dioxide, water and nitrogen (this is the origin of the “three-way catalyst” term for catalysts use in gasoline vehicles and of “oxidation catalyst” for catalysts use in diesel vehicles).
In order to achieve these goals, the manifolds are developed as a built-in solution to the catalytic converter, positioned as close as possible to the engine, thus guaranteeing a fast converter light-off, minimum weight and compact solutions.