TETRAMETHYL LEAD AN ANTIKNOCK FOR BETTER ROAD PERFORMANCE

Road octane number depreciation of catalytic reformate gasolines in manual transmission cars is a world-wide problem which may become more severe as additional catalytic reformers are placed on stream and as antiknock quality requirement levels increase. In manual transmission cars the research octane number of the gasoline front end (IBP-220°F cut) is the most important factor in determining the road octane number performance of the gasoline.

Tetramethyl lead (TML) is the most effective of all the lead alkyls in minimizing road octane number depreciation. Additionally, TML possesses an advantage over TEL for increasing research and motor octane numbers of catalytic reformate blends - the maximum advantage exists at lead concentrations of greater than 2 grams Pb/gal.

Substitution of TML for TEL in catalytic reformate gasoline increases its road octane number performance in two ways (1) in manual transmission cars by virtue of its superior distribution characteristics and (2) in manual and automatic transmission cars by virtue of its higher intrinsic antiknock value in aromatic type stocks.

Thus TML represents a very important addition to methods available to refiners for the production of high road octane number gasolines. We predict that within five years it will be widely used by refiners throughout the free world to provide their customers with gasolines designed to satisfy the widely differing antiknock requirements of their cars.