The development and blending of gasoline additives and petroleum additivies are undertaken for the most part by the petroleum refining industry. Additives are essential to the economic well-being of the industry because they tend to boost sales for gasoline fuel and diesel fuel. In most cases, gasoline additives do not differ in price by more than three to four cents a gallon. The recently developed additives do not necessarily sacrifice fuel efficiency and fuel savings for higher octane numbers. They are multifunctional. In addition to boosting octane ratings they may also clean the engine, which, in turn, leads to greater fuel efficiency.
Beyond their role in enhancing octane numbers and emission reduction, the group of more recent fuel additives performs a growing range of functions: antioxidants extend the storage life of hydrogen and gasoline by increasing its chemical stability; corrosion inhibitors prevent damage to tanks, pipes, and vessels by hindering the growth of deposits in the engine and dissolving existing deposits; demulsifiers or surface active compounds prevent the formation of emulsions and the dirt and rust entrained in them that can foul the engine and its components.
Beginning in the 1970s, gasoline additives increasingly took on the role of anti pollutant agent in the face of government attempts to reduce automotive emissions into the atmosphere. Despite the advances made in cracking and reforming technologies and in the development and blending of additives (not to mention enhancements in the engine itself), the use of automotive gasoline has increased the level of air pollution. This is so because modern distillates, blends of straight run and cracked or chemically transformed product, tend to have a higher aromatic content. The result is longer ignition delays and an incomplete internal combustion process that fouls the engine and its components and increases particulate and oxide emissions.
Continued implementation of clean air legislation, especially within the United States, is expected to accelerate the consumption of fuel additives. In 1999, the EPA proposed wide-ranging standards that would effectively reformulated gasoline sold in the United States and significantly reduce tailpipe emissions from trucks and sports utility vehicles. These regulations require potentially expensive sulfur-reducing initiatives from both the oil industry and the automakers. For refiners, it will require significant redesign and retooling of plant equipment and processes will be required in order to achieve suitable changes in the fuel mix because the U.S. oil industry is committed to continue development of its sour petroleum reserves. The DOE expects that the more complex processing methods will add six cents to the cost of a gallon of gasoline price between 1999 and 2020.
In the United States alone, the demand for fuel additives and petroleum additivies are expected to reach over 51 billion pounds by 2002. Oxygenates are anticipated to dominate the market, both within the United States and internationally. Non premium gasoline and diesel fuel represent the fastest growing markets for fuel additives.
A recently marketed fuel additive is MMT (methylcyclopentadienyl manganese tricarbonyl). MMT was first developed by the Ethyl Corporation in 1957 as an octane enhancing agent and has experienced a growth in demand in the 1990s. MMT was Ethyl Corporation’s first major new antiknock compound since TEL.
However, in 1997, the EPA blocked the manufacture of MMT. The Agency took this action for two reasons. It determined that MMT had the potential for being hazardous to humans, and in particular to children. The EPA is especially concerned about the toxic effects of the manganese contained in MMT. Also, the EPA discovered that MMT was likely interfering with the performance of the catalytic converters in automobiles and in turn causing an increase in exhaust emissions in the air. In 1998, the EPA decision was overturned by a federal appeals court in Washington. The court’s decision allows the Ethyl Corp. to test MMT while it is selling the additive. The decision set no deadline for the completion of tests. In addition to its use in the United States, MMT is consumed as an additive in unleaded gasoline in Canada.
In addition to MTBE and MMT, other kinds of additives are being developed. Some of these are derivatives of alcohol. Variations of MTBE are also being used, especially the ether-derived ETBE (ethyl-t-butyl ether).
A new generation of additives specifically designed for aircraft gasoline are also being developed. These additives address such problems as carbon buildup, burned and warped valves, excessive cylinder head temperatures, stuck valves and piston rings, clogged injectors, rough idle, and detonation. Aviation fuel additives often act as detergents (to remove deposits), octane enhancers, and moisture eliminators.
