Gasoline Additives

Gasoline Additives and Combustion Modifiers

The trend in the U.S. car population toward more critical fast burn or lean burn engines is expected to continue for the foreseeable future.

Therefore, the need to prevent deposits from forming in engines, particularly in the combustion chamber and on intake valves, will grow in importance. With such advances, the problem of octane requirement increase will be overcome by a new class of additives. Octane requirement increase reduction may emerge as a strategy to lessen the refining constraints imposed by marketplace and regulatory forces the "octane race" and EPA and statewide regulations on gasoline volatility and aromatics reduction.

The demand for high-quality fuels has resulted in the use of many different additives which are introduced to the gasoline at refineries and product terminals. Additives injected at the refinery are designed to help the product meet American Society for Testing and Materials gasoline specifications, provide retail brand differentiation and meet the individual requirements of multiple customers.

Since 1985, when automakers began making a wholesale switch from carburetors to fuel injectors, gasoline engine cleanliness has come to the fore as a major issue within the industry first for the control of fuel injector deposits and later for the prevention of intake valve deposits.

Gasoline additives are designed to perform a wide variety of specific functions. The two broad applications of gasoline additives are:

To meet specifications whether external or internal, protect distribution systems and automotive parts and meet possible competitive gasoline performance.

To provide an advantage to gasoline, particularly for advertising purposes, by differentiating one's product from being fungible or common to non-fungible or unique.
Among classes of additives, which include antiknocks, corrosion inhibitors and antioxidants, performance additives are expected to experience the greatest growth in the coming decade. Performance additives include detergents, dispersants, anti-icers, combustion enhancers/modifiers, fluidizer oils and flow improvers. All these additives improve either fuel or engine efficiency or durability. Within the category of performance additives, detergents and dispersants are known collectively as deposit control additives.

Combustion Modifiers

This group includes those additives that in some way alter or enhance combustion in the engine. In the broadest sense, it would include those anti-knocks such as tetraethyl lead which are added in minute portions. However, the more accepted definition would apply to products called scavengers such as ethylene dibromide used to convert combustion products of lead alkyls to other products that can be removed in the exhaust gas.

Deposit modifier additives also can be used to raise the glow temperature of deposits to avoid pre-ignition. However, this additive group is more common to leaded gasolines a shrinking market.

Future Challenges, Needs and Market Opportunities

Emissions requirements continue to become increasingly more stringent and because intake valve deposits have an effect on vehicle warm-up performance, detergent and detergent-dispersant additives will be needed to control this problem. New, emerging additives should possess both "keep clean" and "clean up" properties. As of January 1, 1995, no gasoline in the United States can be marketed without an approved detergent additive package. In general, future gasoline performance additive formulation requirements can be broken down into the following categories:

Reduced Vapor Pressure
-Lower evaporation
-Refueling and running loss elimination

Composition Varied
-Reduce reactivity of vehicle emissions
-Improve flame speed n Fuels

Reduced Aromatics
-Lower hydrocarbon emissions
-Reduce engine deposits
-Lower exhaust as reactivity

Improved Additives
-Reduce engine deposits
-Lower octane requirement increase
-Enhance catalyst performance

Use of Oxygenates such as Ethers and Alcohols
-Reduce carbon monoxide emissions
-Improve octane quality

In summary, the importance of limiting octane requirement increase will be increasingly accepted by motorists as well as fuels specialists. New engine designs will pressure researchers to develop increasingly sophisticated packages. Marketing opportunities will arise for those who develop additives that clean engines, keep them clean and reduce octane requirement increase.