The addition to gasoline of a lead-containing compound called tetraethyllead was an attempt to enhance engine performance. The use of this compound was phased out when it was found to destroy the effectiveness of the catalytic converter (described below) which is used to reduce emissions of carbon monoxide, hydrocarbons and NOx. Tetraethyllead is just one member of a group of compounds, called octane boosters, which can be added to gasoline to increase its octane number. Other compounds that have been used as octane enhancers over the years include methanol (CH3OH) and ethanol (C2H5OH). Each of these alcohols has an oxygen atom in its molecular structure. For that.
