Leaded gasoline utilization

In the Central European countries, the main sources of the environmental pollution and human exposure to lead are the exhaust of vehicles using leaded gasoline, industrial processes that utilize lead and lead compounds (ferrous and non-ferrous metal smelting and processing, and battery manufacturing and dismantling), and combustion sources. 

However, despite all the progress being made, the uncontrolled production unavoidably leads to environmental problems such as climate change or emission of toxic products. For example, dioxins and furans are unintentionally formed and released from various sources like open burning of waste, thermal processes in the metallurgical industry, residential combustion sources, motor vehicles, particularly those burning leaded gasoline, fossil fuel-fired utility and industrial boilers, waste oil refineries etc... 

Alkyl lead compounds are extremely effective gasoline antiknock agents. By decomposing to form lead oxide compounds during the gasoline combustion process, lead alkyls interrupt the rapid chain scission reactions which lead to combustion knock. Also, lead alkyls help to prevent exhaust valve seat wear and may minimize octane requirement increase. However, unless utilized in conjunction with lead scavengers such as 1,2-dichloromethane, lead deposits can accumulate within the gasoline combustion chamber. 

The enhanced diffusivity of polynuclear compounds in sc C02 has been utilized to enhance catalyst lifetimes in both 1-butene/isoparaffin alkylations (Clark and Subramaniam, 1998 Gao et al., 1996). The former may be catalyzed using a number of solid acid catalysts (zeolites, sulfated zeolites, etc.), and the use of sc C02 as a solvent/diluent permits the alkylations to be carried out at relatively mild temperatures, leading to the increased production of valuable trimethylpentanes (which are used as high-octane gasoline blending components). The enhancement of product selectivity in the latter process is believed to result from rapid diffusion of ethylbenzene product away from the Y-type zeolite catalysts, thus preventing product isomerization to xylenes. 

Total domestic capcity of MTBE in the US is, however, limited by the availability of isobutylene. The most available source of isobutylene is from ethylene crackers and if all from that source were utilized to produce MTBE this would yield only 50,000 bbl/day of MTBE. All available isobutylene would produce 200,000 bbl/day of MTBE. At blends of 7%, this would only satisfy the existing unleaded gasoline market, but not that being opened up by the phasing down of lead in gasoline scheduled for October of this year. 

Fluid Catalytic Gasoline (FCC) full boiling range gasoline has a respectible RON of about 92 and an R+M/2 of around 87. Since current no-lead grade specifications include 87 R+M/2, FCC gasoline can be utilized directly in the no-lead pool. 

The main anthropogenic sources of lead include lead-based paints, solder, and metallurgy. Even though utilization of the alkyllead compounds such as gasoline additives has already been regulated, the persistence of various lead forms in the environment is still an issue (Table 3). ICP-MS detection of lead has been used in hyphenation of GC, ion exchange, ion-pairing LC, and, to a lesser extent, SFC. The... 

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