Lead additive

Adding lead to a fuel increases octane numbers by several points. From an RON of around 92, the increase is on the order of 2 to 3 points for 0.15 g Pb/1 and of 5 to 6 points for 0.4 g Pb/1. For higher concentrations the effect of saturation appears and additional improvement in the octane number becomes more modest. The preceding values concern the RON as well as the MON. Nevertheless, one more often observes slightly larger increases for the RON. In other words, lead addition tends to increase the sensitivity slightly (on an order of one point for 0.4 g Pb/1). 

Typical compositions of gasolines according to blending stock origin. Before lead addition. 

For two decades, the Ethyl Corporation had controlled the worldwide market for the tetraethyl lead additive discovered by Thomas Midgley, Jr. (Chapter 6). Ethyl s 2 million annual advertising budget identified tetraethyl lead with baseball, football, and the American Way of Life. The company funded almost all the research about tetraethyl lead s effect on human health. As a result, research on tetraethyl lead had focused on safety in the factory workplace rather than on the health of the general population. 

The primary source of lead in the environment has historically been anthropogenic emissions to the atmosphere. In 1984, combustion of leaded gasoline was responsible for approximately 90% of all anthropogenic lead emissions. EPA phased out the use of lead alkyls in gasoline, however, and by 1990, auto emissions accounted for only 33% of the annual lead emissions (EPA 1996h). Use of lead additives in motor fuels was totally banned after December 31, 1995 (EPA 1996f). The ban went into effect on February 2, 1996. Atmospheric deposition is the largest source of lead found in soils. Lead is transferred... 

Grandjean P, Andersen O. 1982. Toxicity of lead additives. Lancet 2 333-334. 

A careful characterization of copolymers is quite time consuming and a combination of methods as discussed in Section 6.1 might be considered. In practice the situation is often complicated by an amphiphilic character of the copolymers, which leads additionally to micelle formation. 

The design aim of the Hydrocol refinery was to produce abetter than 80% yield of motor gasoline from the Fe-HTFT syncrude at a quality that would be acceptable for the market (MON of 80 after tetraethyl lead addition). The refinery design (Figure 18.2) addressed the issues specific to the Hydrocol Fe-HTFT syncrude ... 

Another group of powerful incentives is concerned with the manufacture of fuels from different raw materials, notably liquid hydrocarbons from natural gas. The removal of lead additives from gasoline has necessitated the introduction of new hydrocarbon formulations and new additives, all made by new processes. 

Soil Pb is an important pathway of human Pb exposure (Mielke Reagan 1998). Empirical evaluation between soil Pb and BPb indicated a strong positive and nonlinear association between soil Pb and BPb (Mielke et al., 2007a). The soil Pb footprint of New Orleans indicates that in the case of public and private properties an enormous disparity exists between the inner- city and outlying areas of New Orleans that cannot be attributed to older Pb-based paint alone dust Pb from the previous use of lead additives to gasoline provide a better explanation between... 

Lead addition improves machinability and sliding-wear properties of bearings. It is usually less than 2% of the bronze composition. 

Environmental considerations, including removal of lead additives as well as carcinogenic alkenes and aromatics from gasoline, increase the significance of isomerization to provide gasoline of suitable octane numbers. 

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