Oil companies are being required to offer new gasolines that burn more cleanly and have less impact on the environment. Typically, reformulated gasoline (RFG) contains: lower concentrations of benzene, aromatics, and olefins; less sulfur; a lower Reid vapor pressure (RVP); and some percentage of an oxygenate (non-aromatic component), such as methyl tertiary butyl ether (MTBE). MTBE is a high-octane gasoline blending component produced by the reaction of isobutylene and methanol. It was developed to meet the ozone ambient air quality standards, but its unique characteristics as a water pollutant pose a challenge to the Environmental Protection Agency (EPA) in meeting the requirements of the Clean Air Act, the Safe Drinking Water Act, and the Underground Storage Tank Program. The Clean Air Act called for reformulated gasoline to be sold in the cities with the worst smog pollution beginning January 1, 1995. Reformulated gasoline is now used in 17 cities and the District of Columbia.
What kinds of additives are in gasoline and why?
| Additive |
Function |
| Antiknock compounds |
Increase octane number |
| Scavengers |
Remove combustion products of antiknock compounds |
| Combustion chamber |
Suppress surface ignition and spark plug deposit modifiers fouling |
| Antioxidants |
Provide storage stability |
| Metal deactivators |
Supplement storage stability |
| Antirust agents |
Prevent rusting in gasoline-handling systems |
| Anti-icing agents |
Suppress carburetor and fuel system freezing |
| Detergents |
Control carburetor and induction system cleanliness |
| Upper-cylinder lubricants |
Lubricate upper cylinder areas and control intake system deposits |
| Dyes |
Indicate presence of antiknock compounds and identify makes and grades of gasoline |
