Gasoline continued unleaded

Use of bromine-containing additives (ethylene dibromide) in leaded gasoline results in the release of bromomethane in exhaust fumes (about 70-220 pg/m of exhaust) (Harsch and Rasmussen 1977), and this may have been significant source of bromomethane release in the past. Combustion of unleaded gasoline releases much less bromomethane (about 4-5 pg/m ), so current emissions from this source are presumably much lower than previously, and are likely to decrease further as leaded gasoline continues to be phased out. 

Beginning in the 1920s, the compound tetraethyl lead was added to gasoline to improve performance. Unfortunately, the lead showed up in motor vehicle exhaust, where its inhalation posed a serious health hazard. In response to this problem, the Clean Air Act mandated a reduction in lead emissions. It was also discovered that lead in motor vehicle exhaust tended to coat the surface of the catalyst in the catalytic converter, rendering the catalyst ineffective. To remedy both problems, unleaded gasoline was introduced in 1974. Leaded gasoline continued... 

Catalysis. Various forms of zeohte Y find uses in industrial catalytic processes. These have already been listed in Table 31 and account for the second highest annual tomiage use of synthetic zeolites (approx 60 000 metric toimes). This continues to increase as zeohte catalysts aid the shift to unleaded gasoline and to the use of cheaper feedstocks. 

Some laboratory animals that breathed high concentrations of unleaded gasoline vapors continuously for 2 years developed liver and kidney tumors. However, there is no evidence that exposure to gasoline causes cancer in humans. There is not enough information available to determine if gasoline causes birth defects or affects reproduction. For more information on the health effects of gasoline, see Chapter 2 and the ATSDR toxicological profiles for benzene, toluene, xylene, ethylbenzene, 1,2-dibromoethane, 1,3-butadiene, and lead. 

The move to unleaded fuels continues worldwide. However, several countries have increased the aromatics content (by up to 50%) to replace alkyl lead. These highly aromatic gasolines can lead to damage of elastomers and increased levels of toxic aromatic emissions if is used without catalysts. 

To solve this problem, a scheme for the continuous production of unleaded gasoline, based on highly efficient small-sized tubular turbulent mixing devices of original design, has been proposed. 

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