Oxygenated gasolines

MTBE, where isobutylene is reacted with methanol to produce an oxygenate gasoline additive called methyl tertiary butyl ether (MTBE). MTBE is added to gasoline to meet the minimum oxygen requirement for reformulated gasoline. 

National Science and Technology Council, Interagency Assessment of Potential Health Risks Associated with Oxygenated Gasoline, Office of Science and Technology Policy, Executive Office of the President, 1996. 

Oxygenated gasoline is sometimes analyzed by GC-based methods, but it should be noted that the efficiency of purge methods is lower for oxygenates... 

Oxygenated gasoline gasoline with added ethers or alcohols, formulated according to the Federal Clean Air Act to rednce carbon monoxide emissions during winter months. 

The behaviour depends on the type of LCP and can be limited or unsatisfactory with certain concentrated acids, antifreezes, bases, oxygenated gasolines, very hot water and steam, amines, methanol, and phenol. 

Another problem with fermentation products is often the limited outlet. The primary fermentation products such as alcohols require chemical transformations to convert them into species acceptable by the chemical industry as intermediates. This can normally occur through dehydration reactions [77]. For example, ethanol may need to be dehydrated into ethylene, isopropanol into propylene and n-butanol into n-butylene. These reactions are reversed petrochemical reactions and normally lead to products that have a lower selling price than the starting materials under the present structure of the chemical industry. For this reason, bioethanol is still used unchanged as an oxygenated gasoline additive. 

The additives used in oxygenated gasoline are alcohols and ethers, the most common of which are ethanol (ethyl alcohol grain alcohol) and methyl t-butyl ether (MTBE). Two less commonly used additives are ethyl t-butyl ether (ETBE) and t-amyl methyl ether (TAME). The chemical structures of these four additives are shown in the diagram on page 24. 

Kirchstetter, T. W., B. C. Singer, R. A. Harley, G. R. Kendall, and W. Chan, Impact of Oxygenated Gasoline Use on California Light-Duty Vehicle Emissions, Environ. Sci. Technol., 30, 661-670 (1996). 

A properties are lor conventional, non-oxygenated gasoline and desel fuel from Ret [2.17], except where noted. (Numbers include an update in progress as of February 1997.)... 

ETBE Ethyl tertiary butyl ether—an ether made from ethanol and iso-butylene that can be used in reformulated and oxygenated gasolines. 

Table 7.6. Impact of low and high oxygenated gasoline use on California light-duty vehicle emission (Krichstetter et al., 1996)...

White MC, Johnson CA, Ashley, et al. 1993. Exposure to methyl tertiary-butyl ether from oxygenated gasoline in Stamford, Connecticut. Archives of Environmental Health 50(3) 183-189. 

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