In 1922, an American called Thomas Midgely (who also invented CFCs) found that if tetraethyl lead, Pb(CH2CH3)4, was put into petrol, particles of lead and lead oxide PbO are formed on combustion. This helps the petrol to burn more slowly and smoothly, preventing knocking and giving higher Octane ratings. 1,2-dibromoethane is also added to the petrol to remove the lead from the cylinder as PbBr2, which is a vapour and removed from the engine. (This is how lead is released into the environment from leaded fuels). Using higher-Octane leaded petrol meant that more powerful high-compression engines could be built.
View attachment 920813 Lead tetraethyl (left) is a lead atom bonded to a tetrahedral arrangment of ethyl groups. Thus, the molecule can be thought of as a metal atom surrounded by a hydrocarbon cage. The C-Pb bond is quite weak, and in the hot environment of an internal combustion engine it fragments producing lead and C2H5 radicals which can help terminate the combustion process by radical reactions.
IMO....Long story shortened....TEL works great...BUT....with advent and requirement of the catalytic converter, TEL was removed because it "poisons" the platinum & palladium elements rendering the conversion process ineffective.
There are certain factions of our society believe that "green house gases" are destroying the atmosphere. The increase in these greenhouse gases are always blamed on coal fired and natural gas fired generation plants.....but how much of these generated greenhouse gases are attributed to the automotive catalytic converter?
The catalytic converter's reaction is:
Typically, there are two different catalysts in a catalytic converter:
- One of them tackles nitrogen oxide pollution using a chemical process called reduction (removing oxygen). This breaks up nitrogen oxides into nitrogen and oxygen gases (which are harmless, because they already exist in the air around us).
- The other catalyst works by an opposite chemical process called oxidation (adding oxygen) and turns carbon monoxide into carbon dioxide. Another oxidation reaction turns unburned hydrocarbons in the exhaust into carbon dioxide and water.
In effect, three different chemical reactions are going on at the same time. That's why we talk about three-way catalytic converters. (Some, less-effective converters carry out only the second two (oxidation) reactions, so they're called two-way catalytic converters.) After the catalyst has done its job, what emerges from the exhaust is mostly nitrogen, oxygen, carbon dioxide, and water (in the form of steam).
Should we do away with catalytic converters on cars as greenhouse gas generators?? It would be nice....but..that will never happen...
Just my opinion of course.
BOB RENTON