COMSATS Institute of Information Technology

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Antioxidants

Their role as additives in fuels

Presented by

Noaman Ahmed CIIT/SP10-BEC-037/LHR

Antioxidants and their purpose

• A molecule that inhibits the oxidation of other molecules

• They are used as fuel additives when creating fuel blends

AH! What is this ? Looks

like an oil gum. What

should I do now ?

Use antioxidants! Dummy!

• Oxidation reactions can produce free radicals leading to chain reactions

• Antioxidants terminate the chain reactions by disrupting radical intermediates

• Antioxidants prevent gumming in gasoline (IC Engines)

• Antioxidants deactivate metals (that cause oxidation) present in fuels

• Antioxidants prevent decomposition of lubricant base stocks

Substituted phenols and derivatives of phenylenediamine – Common antioxidants used to

inhibit gum formation in gasoline

Oxidation of lubricating oils

• Lubricating oils, when poured into engines, go under oxidation in air due to

numerous factors including

• Heat

• High Pressure

• Presence of metals (oxidizing agents)

How antioxidants work ?

• Oxidation takes place in three steps

• Initiation

• Propagation

• Termination

• The antioxidant part

Some common fuel antioxidant additives

• N,N′-Disalicylidene-1,2-propanediamine

• A metal deactivating compound in motor oils

• 2,4-Dimethyl-6-tert-butylphenol

• An anti-gumming agent

References

• Dr. Neil Canter (ed.), Use of antioxidants in automotive lubricants, Tribology and

Lubrication Technology, September 2008. – www.stle.org

• http://www.howstuffworks.com/5-symptoms-of-oil-deposits.htm#page=0

• http://en.wikipedia.org/wiki/Category:Fuel_antioxidants