Leaded Petrol

Use of leaded petrol, and why its use was phased out

Leaded fuel or leaded petrol is defined as fuel oil with the addition of antiknock agents that are mixture of Tetraethyl lead & dibromethane. TEL (tetraethyl lead) blended with lead by-products like dibromethane or dichloromethane was used as a famous antiknock agent and octane booster in petrol mainly in efforts to increase fuel mileage & decrease engine knocking.

Who is credited with the invention of leaded petrol?

Thomas Midgley Jr. is regarded with his discovery of TEL efficient anti-knocking agent. Midgley Jr. was a US chemist & mechanical engineer pioneering his field with the latest research regarding lead development and octane boosting. Midgley played his important role in a team of scientists headed by Charles F. Kettering to develop TEL as well as world’s first ever CFCs (chlorofluorocarbons). At the time of his innovations and discovery in petroleum and chemical industry, he had been credited with over 100 patents that eventually ripped his heritage when it was later found that these discoveries had more negative impacts on the environment than positive ones. Thomas Midgley Jr. received his graduation from Cornell University in 1911 in mathematical engineering and joined Delco in Ohio. In 1916, creator of Delco, Charles F. Kettering allocated Midgley with a task of eliminating loud & unpleasant knocking sound that earlier engines used to make. Soon Midgley figured out knocking was the result of petrol presently processed in the US. Numerous years of efforts in research led Midgley to the discovery of adding Tetraethyl lead to work very effective in eliminating knocking sound. This fuel was named as ethyl gasoline. Although the new gasoline type was successful in eliminating knocking sound, but not without its costs of lead deposits on engine valves that formed over time thereby decreasing engine efficiency. As a result, Midgley further researched on this problem and came up with the addition of Ethyl Dibromide as the final solution to prevent engine valves from lead depositing.

What is engine knocking?

Knocking is considered as an abnormal combustion resulting in fuel wastage and inefficiencies of the combustion engine. Leaded petrol helped to prevent engine knocking.

How did GM use TEL (lead) to promote its fuel?

In order to quickly adapt to ever changing standards, GM promoted this substance as Ethyl in order to avoid mentioning lead in reports & newspapers. Soon afterwards, GM and various other oil manufacturing companies in a joint collaborative patent held by Midgley& Kettering started supporting TEL as a better alternative to ethanol fuels. The main motive behind TEL promotion was to enjoy substantial rise in profits by the company that otherwise could not have been possible had they continued to sell ethanol blended gasoline.
Over the concern of safety issues involving TEL in gasoline, reports and conferences were held all over the US. In one such press conference taken place on 30th October, 1924, Midgley poured TEL over his hands and placed his nose in a chemical bottle filled with TEL for 1 minute. He further said that he could practice this habit daily without having any ill effects on his health.

After effects of Midgley’s death

Midgley died on 2nd November 1944, but the after effects of lead usage as fuel additive were not witnessed for almost 30 years after his death. Increasing lead toxicity levels in the environment along with ozone depletion raised concerns amongst experts & analysts all over the world. It was this time when different countries started thinking about phasing out lead from gasoline.

Why had lead been phased out of gasoline?

Lead is a highly toxic metal that was responsible for causing serious health hazards during the decades it had been popularly used all over the world as a fuel additive. Some of the worst health problems that could be blamed for increasing levels of lead due to combustion from engines are kidney failures, cardiac diseases, brain damage, pulmonary, and lung diseases etc.
Thomas MidgleyJr, himself got severe lung infection due to constant working with lead in laboratories. Catalytic converters started to be used successfully during the early 1970s and lead based fuels were responsible for lead layering of the catalytic converters resulting in lead clogging. Lead had also been phased out completely from spray paints and various other chemicals.
It was not until 29th January 1996, when a proposed decision by the EPA was taken to completely ban leaded petrol and phase out lead from petrol throughout the US although the shift had already been started around 15 years earlier than this time period. Leaded petrol is not only banned but illegal to sell in many parts of the world.