![Red Diesel - geograph](https://upload.wikimedia.org/wikipedia/commons/e/ed/Red_Diesel_-_geograph.org.uk_-_339947.jpg)
Fuel dyes are
dyes added to
fuels, as in some countries it is required by law to dye a low-tax fuel to deter its use in applications intended for higher-taxed ones. Untaxed fuels are referred to as "dyed", while taxed ones are called "clear" or "white".
Aviation gasoline
Avgas (aviation gasoline, also known as aviation spirit in the UK) is an aviation fuel used in aircraft with spark-ignited internal combustion engines. ''Avgas'' is distinguished from conventional gasoline (petrol) used in motor vehicles, whi ...
is dyed, both for tax reasons (avgas is typically taxed to support aviation infrastructure) as well as safety (due to the consequences of fuelling an aircraft with the wrong kind of fuel).
Types of dyes
The dyes used have to be soluble in the fuels they are added to and therefore in
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...
-based
nonpolar
In chemistry, polarity is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole moment, with a negatively charged end and a positively charged end.
Polar molecules must contain one or more polar ...
solvents ("
solvent dye A solvent dye is a dye soluble in organic solvents. It is usually used as a solution in an organic solvent.
Solvent dyes are used to color organic solvents, hydrocarbon fuels, waxes, lubricants, plastics, and other hydrocarbon-based nonpolar mat ...
s"). Red dyes are often various
diazo dye
Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C-N=N ...
s, e.g.,
Solvent Red 19
Sudan Red 7B, also known as Solvent Red 19, Ceres Red 7B, Fat Red 7B, Hexatype carmine B, Lacquer red V3B, Oil violet, Organol bordeaux B, Sudanrot 7B, Typogen carmine, and C.I. 26050, is a red diazo dye. Chemically it is ''N''-ethyl-1- ''p''-(ph ...
,
Solvent Red 24
Sudan IV (C24H20N4O) is a lysochrome (fat-soluble dye) diazo dye used for the staining of lipids, triglycerides and lipoproteins on frozen paraffin sections. It has the appearance of reddish brown crystals with melting point 199 °C and maxi ...
, and
Solvent Red 26
Solvent Red 26, also known as Oil Red EGN or C.I. 26120, is a purplish red synthetic azo dye. It is soluble in oils and insoluble in water.
Its main use is as a standard fuel dye in the US mandated by the US IRS
The Internal Revenue Ser ...
. Anthraquinone dyes are used for green and blue shades, e.g., Solvent Green 33,
Solvent Blue 35
Oil Blue 35 is a blue anthraquinone dye used for colouring alcoholic and hydrocarbon based solvents, including oils, fats, and waxes. It is used also in lacquers and inks. In some countries, it is used as a fuel dye. It is also used in some blue ...
and Solvent Blue 26.
The pure dyes found in modern liquid petroleum dyes are longer alkyl side chain forms of traditional dyes and normally multiple chain length variations of the chromophore are found within a typical commercial liquid petroleum dye.
For instance, Sudan Red 462 is a form of Solvent Red 19, with the ethyl side chain replaced by either a 2-ethylhexyl or a tridecyl side chain. The longer branched side chains improve solubility dramatically, but in some cases the high solubility prevents the dye being isolated as a crystal, except at very low temperatures.
The high-solubility liquid dyes originated with Morton International and BASF (
ACNA Italy) as the primary inventors.
For instance, Morton International created Solvent Blue 98 as a high solubility form of Solvent Blue 35. BASF created Solvent Blue 79 as its high solubility form of Solvent Blue 35.
In some cases it is possible, with normal solvents—e.g., xylene—to prepare stable (to -20C) solutions at 65% "solids" content. The original powder dye form of the chromophore would not be soluble beyond 2% in xylene.
Only a few refineries worldwide still use powder dyes for colouring fuels, as although they are lower cost per active molecule of dye chromophore than the modified forms, they have significant handling issues and health and safety issues that inherently arise from the handling of
azo dyes
Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C-N=N ...
(reds/yellows/green mixes). It is advantageous to mix a liquid with a liquid instead of handling powdered dyes into a liquid.
Fuel dye in the European Union
After August 2002, all
European Union
The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been de ...
countries became obliged to add about of
Solvent Yellow 124
Solvent Yellow 124 is a yellow azo dye used in European Union as a fuel dye. It is a marker used since August 2002 to distinguish diesel fuel intended for heating from a higher-taxed motor diesel fuel. It is added to fuels not intended for motor v ...
, a dye with structure similar to
Solvent Yellow 56
Solvent Yellow 56 is the organic compound ''N'',''N''-diethyl-''p''-(phenylazo)aniline. It is an azo dye, which has the appearance of a reddish yellow powder. Its EINECS number is 219-616-8.{{Ullmann, first1 = Klaus, last1 = Hunger, first2 = Pet ...
, to heating fuel. This dye can be easily hydrolyzed with acids, splitting off the
acetal
In organic chemistry, an acetal is a functional group with the connectivity . Here, the R groups can be organic fragments (a carbon atom, with arbitrary other atoms attached to that) or hydrogen, while the R' groups must be organic fragments n ...
group responsible for its solubility in nonpolar solvents, and yielding a water-soluble form. Like a similar
methyl orange
Methyl orange is a pH indicator frequently used in titration because of its clear and distinct color variance at different pH values. Methyl orange shows red color in acidic medium and yellow color in basic medium. Because it changes color at the ...
dye, it changes color to red in acidic pH. It can be easily detected in the fuel at levels as low as 0.3 ppm by extraction to a diluted
hydrochloric acid
Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid
Acid strength is the tendency of an acid, symbol ...
, allowing detection of the red diesel added into motor diesel in amounts as low as 2–3%.
The European Union has announced that a new and better marker has been found to replace Solvent Yellow 124. On 14th February 2022 the EU Commission published their decision dated 17th January 2022 naming the new marker as "ACCUTRACE(TM) Plus" ButoxyBenzene with a transition date ending 18 January 2024
United Kingdom
![Petrol_pump,_Aherlow](https://upload.wikimedia.org/wikipedia/commons/7/7d/Petrol_pump%2C_Aherlow.jpg)
In the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...
, "red diesel" is dyed gas oil for registered agricultural or construction vehicles such as tractors, excavators, cranes and some other
non-road applications such as boats. Red diesel carries a significantly reduced tax levy compared to un-dyed diesel fuel used in ordinary road vehicles. As red diesel is widely available in the UK, the authorities regularly carry out roadside checks. Unauthorised use incurs heavy fines but despite this, spot checks have occasionally found as many as one in five motorists using red diesel.
Red diesel can also be used in road vehicles which are
registered as off road with the DVLA provided they are only used on private land. On 14 July 2014, the European Commission announced it was referring the United Kingdom to the European Court of Justice over the use of red diesel in propelling private pleasure craft on water. It believed the UK was not properly applying EU regulations for the fiscal marking of fuels.
On 18 November 2014, a new measure to combat fuel laundering was set to result in the illegal trade being "virtually eliminated" in the United Kingdom, according to
HM Revenue and Customs
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. A new dye was introduced in April 2015 in the United Kingdom and the
Republic of Ireland
Ireland ( ga, Éire ), also known as the Republic of Ireland (), is a country in north-western Europe consisting of 26 of the 32 Counties of Ireland, counties of the island of Ireland. The capital and largest city is Dublin, on the eastern ...
.
Carbon offset red diesel
Carbon offset
A carbon offset is a reduction or removal of emissions of carbon dioxide or other greenhouse gases made in order to compensate for emissions made elsewhere. Offsets are measured in tonnes of carbon dioxide-equivalent (CO2e). One ton of carb ...
red diesel is, as of 2014, available in the UK. It is marketed as an environmentally friendly alternative to regular red diesel. There is an extra cost incurred when purchasing carbon offset red diesel; however, some suppliers of the fuel are donating the extra cost to projects aimed at lowering carbon emissions, meaning they make no extra profit from the sale of the fuel.
Finland
![Diesel-Motoroil Pump](https://upload.wikimedia.org/wikipedia/commons/f/fe/Diesel-Motoroil_Pump.jpg)
Low-tax dyed fuel oil ( fi, polttoöljy; sv, brännolja; always abbreviated on nozzles as ''MPÖ'') is available in many rural petrol stations in Finland, primarily intended for certain types of non-road vehicles such as tractors and driveable construction vehicles. Until 2002,
furfural was used to dye fuel oil in Finland, when it was replaced with Solvent Yellow 124. Since 2008, boats and pleasure craft are no longer legally allowed to use low-tax fuel oil; instead, taxable diesel must be used for fuel.
Poland
Currently there are no naked-eye visible dyes in car fuels sold in Poland. Previously, during the time of Communist Party rule, the state-owned CPN fuel monopoly dyed leaded gasolines (marketed as "ethilins") in the following colors: 78 – blue, 86 – green, 94 – yellow, 98 – red. Diesel fuel, although unleaded, was also dyed a brown color.
Fuel dye in North America
In the
United States of America
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 primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territo ...
, the
Environmental Protection Agency mandates use of a red dye to identify fuels for off-road use.
Solvent Red 26
Solvent Red 26, also known as Oil Red EGN or C.I. 26120, is a purplish red synthetic azo dye. It is soluble in oils and insoluble in water.
Its main use is as a standard fuel dye in the US mandated by the US IRS
The Internal Revenue Ser ...
is used in the United States as a standard, though it is often replaced with
Solvent Red 164
Sudan III is a lysochrome (fat-soluble dye) diazo dye. It is structurally related to azobenzene.
Uses
It is used to color nonpolar substances such as oils, fats, waxes, greases, various hydrocarbon products, and acrylic emulsions. Its main ...
, which is similar to Solvent Red 26 but with longer
alkyl
In organic chemistry, an alkyl group is an alkane missing one hydrogen.
The term ''alkyl'' is intentionally unspecific to include many possible substitutions.
An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloa ...
chains. The
Internal Revenue Service regulation mandates use of the same red dyes, in fivefold concentration, for tax-exempt diesel fuels such as
heating oil; their argument for the higher dye content is to allow detection even when diluted with "legal" fuel. Detection of red-dyed fuel in the fuel system of an on-road vehicle will incur substantial penalties.
Fuel laundering
Organised crime
Organized crime (or organised crime) is a category of transnational, national, or local groupings of highly centralized enterprises run by criminals to engage in illegal activity, most commonly for profit. While organized crime is generally th ...
gangs may "launder" low-price dyed fuel, removing the dye and selling it illegally to unsuspecting motorists at the higher price of undyed fuel. Paramilitary groups connected to
political unrest in Northern Ireland have established laundering plants on both sides of the
Irish border. In 2004, Northern Irish police discovered an illegal facility capable of removing the dye from per year.
In 2009, customs officials shut down a plant capable of removing the dye from 6.5 million litres of fuel per year. In 2011, a plant capable of processing 30 million litres was discovered.
Fuel theft
Fuel is being dyed by companies such as
Bord na Móna in Ireland in an effort to combat the widespread theft of fuel.
Dyes used by country
Some dyes required in some countries are listed here:
References
External links
Minnesota State Patrol Commercial Vehicle Enforcement Dyed Fuel ProgramCrown Oil fuel dye information{{Use dmy dates, date=February 2020