Gasoline tetraethyl-lead removal

At the time this paper was written many questions relating to removal of tetraethyl lead (TEL) from gasolines are still unsettled, but these relate principally to timing, octane levels, etc., and it seems clear... 

Sulfur hexafluoride accelerates the pyrolysis of paraffin hydrocarbons (164), lowers the octane number of gasoline containing lead tetraethyl (189), removes silicon from a platinum catalyst when heated to 800 to 1000° (206) and catalyzes the reaction of ammonia with a ketone and aldehyde to give a substituted pyridine (196). It may be used at high pressure to fill a fuse. When the fuse blows an arc is prevented (210). 

Through natural occurrence and its industrial use, lead is ubiquitous in the environment. The removal of tetraethyl lead from gasoline has resulted in a decline in blood levels from 13 pg/dL in the 1980s to <5 pg/dL in the general U.S. population. However, many children living in central portions of large cities still have blood lead concentrations >10 pg/dL. The primary sources of environmental exposure to lead are leaded paint and drinking water most of the overt toxicity from lead results from environmental and industrial exposures. 

Tetraethyl lead, a gasoline additive and significant pollutant, was removed from gasoline not because of human health issues but because it poisoned catalytic converters, needed for fuel efficiency. 

Shape-selective reactions have been extensively studied since zeohtes were first used in catalytic crackers during 1967" and Mobil has introduced several octane-boosting processes since 1968. ° Gasoline composition and octane number were reviewed when the Clean Air Act was passed in 1970. This mandated the phased removal of tetraethyl lead from gasoline as catalytic converters (see Chapter 11) were introduced to treat automobile exhaust gas. Octane boosting was the first in a series of measures that led to reformulated gasoline and improved exhaust emissions standards. 

Tetraethyl- and tetramethyl-lead are removed from internal combustion engines by scavenging, i.e., a reaction with halogenated hydrocarbon gasoline ad-... 

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