Metal deactivator
Encyclopedia
Metal deactivators, or metal deactivating agents (MDA) are fuel additives and oil additive
Oil additive
Oil additives are chemical compounds that improve the lubricant performance of base oil . By utilizing the same base stock, many different oils can be manufactured, each with its distinctive properties. Additives comprise up to 5% by weight of some oils.Nearly all commercial motor oils contain...

s used to stabilize fluids by deactivating (usually by sequestering
Sequestrant
A sequestrant is a food additive whose role is to improve the quality and stability of the food products. Sequestrants form chelate complexes with polyvalent metal ions, especially copper, iron and nickel, which serve as catalysts in the oxidation of the fats in the food...

) metal ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

s, mostly introduced by the action of naturally occurring acids in the fuel and acids generated in lubricant
Lubricant
A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...

s by oxidative processes with the metallic parts of the systems. Fuels desulfurized by copper sweetening
Copper sweetening
Copper sweetening is a petroleum refining process using a slurry of clay and cupric chloride to oxidize mercaptans. The resulting disulfides are less odorous and usually very viscous, and are usually removed from the lower-boiling fractions and left in the heavy fuel oil fraction...

 also contain a significant trace amounts of copper.

Metal deactivators inhibit the catalytic effects of such ions, especially copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

, retarding the formation of gummy residues (e.g. gel
Gel
A gel is a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state...

s containing copper mercaptide). http://www.octel-starreon.com/Products_RFA_Metal_Deactivators.htm Even concentrations of copper as low as 0.1 ppm can have detrimental effects.

An example of a metal deactivator used for gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...

 and jet fuel
Jet fuel
Jet fuel is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is clear to straw-colored in appearance. The most commonly used fuels for commercial aviation are Jet A and Jet A-1 which are produced to a standardized international specification...

s is N,N'-disalicylidene-1,2-propanediamine. It is used in turbine and jet fuel
Jet fuel
Jet fuel is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is clear to straw-colored in appearance. The most commonly used fuels for commercial aviation are Jet A and Jet A-1 which are produced to a standardized international specification...

s, diesel, heating oil
Heating oil
Heating oil, or oil heat, is a low viscosity, flammable liquid petroleum product used as a fuel for furnaces or boilers in buildings. Home heating oil is often abbreviated as HHO...

, and greases
Grease (lubricant)
The term grease is used to describe semisolid lubricants. Although the word grease is also used to describe rendered fat of animals, in the context of lubrication, grease typically applies to a material consisting of a soap emulsified with mineral or vegetable oil...

. It is approved for military and commercial aviation fuel
Aviation fuel
Aviation fuel is a specialized type of petroleum-based fuel used to power aircraft. It is generally of a higher quality than fuels used in less critical applications, such as heating or road transport, and often contains additives to reduce the risk of icing or explosion due to high temperatures,...

s. Benzotriazole and its various derivatives are also common in lubricant
Lubricant
A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...

formulas.
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