Exhaust Emission Control System; Catalytic Converter - Fiat Punto 2004 Training Manual

Fiat Auto S.p.A.
1.3 MULTIJET 16V
FIAT PUNTO TRAINING OUTLINE
(75 & 90 HP) After Sales Training

3.2.19 Exhaust emission control system

3.3 Catalytic converter

The oxidizing catalyst is a post-treatment device to oxidize the CO, HC's and particulate, so as
to transform the same into carbon dioxide (CO2) and water vapour (H2O).
The catalytic converter is made up of a ceramic, honeycomb monolith (1), the cells of which
are soaked with platinum (2), a catalyzing substance of oxidation reactions.
Operation
The exhaust gas flowing through the cells heats the catalyst, thus triggering the conversion of
polluting substances into inert compounds.
The chemical reaction for CO, HC and particulate oxidation is efficient at temperatures ranging
between 200°C and 350°C.
Beyond 350°C, the sulphur contained in the diesel fuel starts oxidizing, thus giving rise to
sulphur dioxide and sulphur trioxide.
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