William
Kovarik
Radford University
and
Matthew E. Hermes
Kennesaw State University
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Fuels and
Society: C. How Lead was Finally Removed from Gasoline
A History
of Decisions that Affects Today's Gasoline Price and
Supply
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1.
Nitrogen
Oxides as Pollutants
2. Catalytic
Converters
3. Catalytic Converter Chemistry
4. Phase-Out of Lead
5. Impact on Fuels
6. Fuel Refinery Chemistry
7. Reformulated Gasolines
8. Back to Alcohol
9. MTBE
10. MTBE Chemistry
11. Organics in Water
12. MTBE Pollution
13. Corporate/Government Decisions -
1990's
14. Impact on Auto Manufacturers
This unit links the
physical and chemical properties of atmospheric
pollutants and tetraethyllead to the decisions to
introduce the catalytic converter.
You will learn about the chemistry of the pollutants we
call smog
You will understand the chemical catalysis and how the
catalytic converter changed fuels and engines.
Analysis of alternate strategies resulted in introduction
of MTBE and its new set of pollution problems.
What will you do to resolve the future of automotive fuel
and engine design.
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| The Facts: From the
mid 1920's until the mid 1980's motor gasoline
fuel contained an additive, tetraethyllead, that
improved fuel performance by preventing
preignition in the cylinders of the engine.
Preignition resulted in damaging and efficiency
and power reducing knocking. Tetraethyllead
is a toxic liquid that killed more than 40
chemical workers during its early development and
manufacturing. Nevertheless, motor companies, oil
companies and the government authorized the
manufacture, distribution and use of
tetraethyllead in gasoline throughout the world.
Pb(C2H5)4
Tetraethyllead (TEL)
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Atlanta Today
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In the late 1960's new anti
pollution initiatives made the automotive
industry look at better ways to reduce nitrogen oxides and carbon
monoxide effluents from the automobile engine.
The nitrogen oxides were at the heart of a
problem we could see - hte brown haze that hung
over the cities - and that we can still see
today! |
| The Solution:
A small canister called the
catalytic converter was installed in US
automobiles beginning in 1976. This device
consisted of heavy metal catalysts imbedded on a
ceramic support. The converter was installed in
the engine exhaust. The converter chemistry was such
that the converter caused oxidation of CO and
reversal of the reaction producing nitrogen
oxides. New Challenge: But
lead in the exhaust stream - the residues of TEL
that had been added to the gasoline to improve
performance - immediately deactivated the converter catalyst. The combination of the
catalytic converter and leaded gasoline did not
work. One of them had
to go, and it was the TEL!!
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1979 Chevrolet
Camaro - Early in the no-lead gasoline era.
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The Questions: So the fuel
and automobile companies now faced the same challenge
they faced in the 1920's - how to develop a compatible
system of fuel and automobile engine that would perform
efficiently.
They reformulated, developed new additives and faced issues of cost and supply. Go through
the units outlined in the concept map that describe fuel reformulation, the reintroduction of alcohol and the
chemistry of a new octane
enhancer, MTBE and the pollution attributed to MTBE.
CH3OC(CH3)3
MTBE
End with a case
discussion looking ahead to the
future of fuels and engines.
Begin with the unit generation of nitrogen oxides as pollutants click on any area
of the concept map below.
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