USE OF NEW OXYGENATES AS GASOLINE COMPONENTS

In addition to conventional hydrocarbons, oxygen containing component - oxygenates - are generally used in gasoline to replace lead components as octane boosters and to reduce exhaust emissions. Such components are alcohols and ethers, of which methyl tertiary butyl ether (MTBE) is most commonly used. Three gasoline grades were studied experimentally by engine and car tests in the laboratory and by a field test with 20 passenger cars. One of the fuels was a reference gasoline containing solely hydrocarbons, the second one contained 11% MTBE and the third one 13% ethyl tertiary butyl ether (FTBE). The oxygen content of the oxygenate-containing gasolines was 2 weight-%. Neither the engine performance measurements nor the field test gave differences in gasoline consumption or engine output. In driveability tests in the laboratory, the oxygenate gasolines were, in cold conditions, superior to the reference gasoline, while no significant differences were observed in the hot-driveability test. On the basis of the road octane requirement tests, a slightly higher octane number is required for the oxygenated fuels than for the hydrocarbon fuel. When using oxygenated fuels, the CO emission of the non-catalyst cars was reduced by 15-20% and the HC emission by about 5%. The corresponding reductions for the catalyst cars were 0-10% (CO) and about 10% (HC). The fuel had no effect on the NO(sub x) emission. At the cold test of 30 min at -20 and +0 deg C the CO emission of the 3-way catalyst engine was reduced on average by 7% and the HC emission by 6-11%.