Gasolines for Low-Emission Vehicles

International concern over air quality and the recognition that the internal combustion engine-powered passenger car is a contributor of atmospheric pollutants has imposed restrictive design criteria upon both the automobile manufacturer and the petroleum refiner. For the passenger car engine builder serving the American market, these criteria have been specified by the emission standards required by the Clean Air Amendments of 1970. On the other hand, gasolines for these low-emitting passenger cars have only recently been specified and their required quality and performance characteristics have not yet been completely spelled out. This paper discusses the influence of emission control requirements on future gasoline quality. Lead antiknocks, hydrocarbon composition, and gross physical properties are among the factors considered and an effort is made to quantify the effects of changes in these characteristics on emissions and to estimate their impact on the industry. It is concluded that future automotive fuels, that is, fuels that will be produced for low-emission vehicles, will be a blend of liquid hydrocarbons, free of lead alkyl antiknocks and other materials deleterious to catalysts. Hydrocarbon composition and volatility will be adjusted to provide optimum emissions control at lowest overall system cost.