Introduction to Catalytic Converters
The Car Pollutes What?!
Reducing Pollution
Other Ways To Reduce Pollution
Pollutants Produced by a Car Engine
In order
to reduce emissions, modern car engines carefully control the
amount of fuel they burn. They try to keep the air-to-fuel
ratio very close to the stoichiometric point, which is
the calculated ideal ratio of air to fuel. Theoretically, at
this ratio, all of the fuel will be burned using all of the
oxygen in the air. For gasoline,
the stoichiometric ratio is about 14.7:1, meaning that for
each pound of gasoline, 14.7 pounds of air will be burned. The
fuel mixture actually varies from the ideal ratio quite a bit
during driving. Sometimes the mixture can be lean (an
air-to-fuel ratio higher than 14.7), and other times the
mixture can be rich (an air-to-fuel ratio lower than
14.7).
The main emissions of a car engine are:
- Nitrogen gas (N2) - Air is
78-percent nitrogen gas, and most of this passes right
through the car engine.
- Carbon dioxide (CO2) - This
is one product of combustion. The carbon in the fuel bonds
with the oxygen in the air.
- Water vapor (H2O) - This is
another product of combustion. The hydrogen in the fuel
bonds with the oxygen in the air.
These emissions
are mostly benign (although carbon dioxide emissions are
believed to contribute to global warming). But because the
combustion process is never perfect, some smaller amounts of
more harmful emissions are also produced in car engines:
These are the three main regulated emissions, and
also the ones that catalytic converters are designed to
reduce.
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Introduction to Catalytic Converters
The Car Pollutes What?!
Reducing Pollution
Other Ways To Reduce Pollution
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