Oxygenated chemical compounds contain
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
as a part of their chemical structure. The term usually refers to oxygenated chemical compounds added to
fuel
A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy b ...
s. Oxygenates are usually employed as
gasoline additive
Petrol additives increase petrol's octane rating or act as corrosion inhibitors or lubricants, thus allowing the use of higher compression ratios for greater efficiency and power. Types of additives include metal deactivators, corrosion inhibit ...
s to reduce
carbon monoxide
Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simpl ...
and
soot
Soot ( ) is a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons. It is more properly restricted to the product of the gas-phase combustion process but is commonly extended to include the residual pyrolysed ...
that is created during the burning of the fuel. Compounds related to soot, such as
polyaromatic hydrocarbons (PAHs) and
nitrated PAHs, are also reduced.
The oxygenates commonly used are either
alcohol
Alcohol most commonly refers to:
* Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom
* Alcohol (drug), an intoxicant found in alcoholic drinks
Alcohol may also refer to:
Chemicals
* Ethanol, one of sev ...
s or
ether
In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again ...
s:
* Alcohols:
**
Methanol
Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is ...
(MeOH)
**
Ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
(EtOH); see also
Common ethanol fuel mixtures
Several common ethanol fuel mixtures are in use around the world. The use of pure hydrous or anhydrous ethanol in internal combustion engines (ICEs) is only possible if the engines are designed or modified for that purpose, and used only in auto ...
**
Isopropyl alcohol
Isopropyl alcohol (IUPAC name propan-2-ol and also called isopropanol or 2-propanol) is a colorless, flammable organic compound with a pungent alcoholic odor. As an isopropyl group linked to a hydroxyl group ( chemical formula ) it is the s ...
(IPA)
**
''n''-Butanol (BuOH)
** Gasoline grade
''tert''-butanol (GTBA)
* Ethers:
**
Methyl ''tert''-butyl ether (MTBE)
**
''tert''-Amyl methyl ether (TAME)
**
''tert''-Hexyl methyl ether (THEME)
**
Ethyl ''tert''-butyl ether (ETBE)
**
''tert''-Amyl ethyl ether (TAEE)
**
Diisopropyl ether
Diisopropyl ether is secondary ether that is used as a solvent. It is a colorless liquid that is slightly soluble in water, but miscible with organic solvents. It is used as an extractant and an oxygenate gasoline additive. It is obtained indust ...
(DIPE)
In the United States
In the
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
, the
Environmental Protection Agency
A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale ...
had authority to mandate that minimum proportions of oxygenates be added to automotive gasoline on regional and seasonal basis from 1992 until 2006 in an attempt to reduce air pollution, in particular
ground-level ozone and
smog
Smog, or smoke fog, is a type of intense air pollution. The word "smog" was coined in the early 20th century, and is a portmanteau of the words '' smoke'' and ''fog'' to refer to smoky fog due to its opacity, and odor. The word was then int ...
. In addition to this North American automakers have in 2006 and 2007 promoted a blend of 85% ethanol and 15% gasoline, marketed as
E85, and their flex-fuel vehicles, ''e.g.''
GM's Live Green, Go Yellow campaign. US
Corporate Average Fuel Economy (CAFE) standards give an artificial 54%
fuel efficiency
Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device ...
bonus to vehicles capable of running on 85% alcohol blends over vehicles not adapted to run on 85% alcohol blends.
There is also alcohols' intrinsically cleaner combustion, however due to its lower
energy density
In physics, energy density is the amount of energy stored in a given system or region of space per unit volume. It is sometimes confused with energy per unit mass which is properly called specific energy or .
Often only the ''useful'' or extrac ...
it is not capable of producing as much energy per gallon as gasoline. Much gasoline sold in the United States is blended with up to 10% of an oxygenating agent. This is known as oxygenated fuel and often (but not entirely correctly, as there are reformulated gasolines without oxygenate) as reformulated gasoline. Methyl ''tert''-butyl ether (MTBE) was the most common fuel additive in the United States, prior to government mandated use of
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
.
References
External links
EPA Definition of Oxygenates
{{Use dmy dates, date=November 2020
Petroleum products
Fuels