alleryStart learning →Why are most catalytic converters preheated by an electric heater?
ATo burn off soot before the engine starts
BTo keep the exhaust gases from condensing
CTo make the metals fully active from the start
DTo raise the pressure of the exhaust stream
Answer & Solution
Correct answer: C. To make the metals fully active from the start
1. Reaction rate rises steeply with temperature, so a cold converter works poorly.
2. Exhaust from a freshly started engine is not yet hot enough to bring the catalyst up to working temperature.
3. During those first minutes the untreated emissions would pass straight through.
4. An electric heater warms the converter before the exhaust arrives.
5. The metals in the catalyst are then fully active from the very start.
6. The heater is about reaction temperature, not about pressure or condensation.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 12 "Kinetics", section 12.7 Catalysis_
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