William
Kovarik |
Fuels and Society B: 3. Additives/Tetraethyllead |
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| Back to 2. Alcohol Fuel as a Replacement 4. TEL Toxicity Back to Start
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3. Additives / TEL Most fuel research within the oil industry involved new ways to create branched chain hydrocarbons in the less volatile fractions of the fuel. Oil industry researchers found that if petroleum was cooked long enough, with enough pressure, and run through the right catalyst, a higher quality anti-knock fuel would result. This trend in research did, in fact, result in the largest increase in anti-knock quality over the years. Charles
F. Kettering, on the other hand, was working on research
problems for the automotive industry. His Dayton
Metal Products Co. was merged with General Motors in 1919
and became the core of GM's research division.
Kettering’s fuel research had opened two very interesting doors. The high percentage solutions – alcohol and benzene -- “appear to be very promising allies” to petroleum, Kettering’s assistants Thomas Midgley and T.A. Boyd said..[i] Alcohol was the “most direct route ... for converting energy from its source, the sun, into a material that is suitable for a fuel...” But alcohol from food crops involved supply problems. Only celluosic biomass had the potential to compete with petroleum over the long run, they believed. The second door -- the“low
percentage class” of solution -- was originally
represented by iodine. It was far too expensive to be
practical, but it led to experiments in 1920 and 1921
that would change the automotive world. The experiments were guided by a
peg board with a portion of the periodic table of
elements pasted on it. The board helped the researchers
compare their tests of already known knock suppressors
(such as bromine, iodine, tellurium, tin and
selenium) and new fuel additives (such as arsenic and
sulfur). Historians have seen it as a beautiful
piece of pure research. The atmosphere in the labs grew
more expectant as the pegboard seemed to point the
way toward the heavy end of the carbon group: silicon,
germanium, tin and lead. Visiting his father in
Massachusetts in late October, Midgley had
antiknock results from each new test sent via telegraph
daily. Tetraethyl tin proved effective, but even
more exciting was the prospect of metallic lead at
the bottom of the column on the peg board. When the chemists finally
delivered a small amount of tetraethyl lead on the
morning of December 9, 1921, the knock in the
one-cylinder laboratory engine was utterly silenced. Even
diluted to a strength of two or three grams per gallon,
or one thousand to one, tetraethyl lead had a remarkable
ability to quiet the relentless knocking.
Midgley, Boyd and others in the lab “danced a very unscientific jig” and hurried off to include Kettering in their victory party. Holding a test tube full of the stuff in his fingers, Kettering suggested, perhaps ironically, the name “ethyl” for the chemical compound tetraethyl lead. Although the term referred to the ethyl alcohol solvent used to dissolve the lead, and utterly confused the question of high percentage versus low percentage solutions, the name Ethyl stuck. Within a few years "Ethyl" became a component of high grade gasolines. [i] Large-scale
production of benzene was questionable. Even if all the
coal mined in the U.S. in 1920 were used to supply
benzene, only about 900 million gallons, or one-fifth of
the U.S. gasoline supply would be replaced, he said.
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