Fuel dyes
Encyclopedia
Fuel dyes are dye
s added to fuel
s, 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".
The dyes used have to be soluble in the fuels they are added to and therefore in hydrocarbon
-based nonpolar solvents ("solvent dye
s"). Red dyes are often various diazo dyes, e.g. Solvent Red 19, Solvent Red 24, and Solvent Red 26
. Anthraquinone dyes are used for green and blue shades, e.g. Solvent Green 33, Solvent Blue 35 and Solvent Blue 26.
It is advantageous to mix a liquid with a liquid instead of handling powdered dyes into a liquid.
The pure dyes found in modern liquid petroleum dyes are essentially 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 essentially 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 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 ultimately they are still lower cost per active molecule of dye chromphore than the modified forms. They have significant handling issues and health and safety issues that inherently arise from the handling of azo dyes (reds/yellows/green mixes).
Aviation gasoline
is dyed, both for tax reasons (avgas is typically taxed to support aviation infrastructure) as well as safety—there being obvious and disastrous consequences of fueling an aircraft with the wrong kind of fuel.
countries became obliged to add about 6 mg/L of Solvent Yellow 124
, a dye with structure similar to Solvent Yellow 56, to all motor diesel fuel. This dye can be easily hydrolyzed with acids, splitting off the acetal
group responsible for its solubility in nonpolar solvents, and yielding a water-soluble form. Like a similar methyl orange
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
, allowing detection of the red diesel added into motor diesel in amounts as low as 2-3%.
, "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 than 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, highly unlikely in a metropolitan area but much more likely in a rural area. Unauthorized 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 SORN with the DVLA provided they are only used on private land. There is also no need to tax a vehicle that is not used on a public road.
mandates use of a red dye to identify high-sulfur fuels for off-road use. Solvent Red 26
is used in the United States as a standard, though it is often replaced with Solvent Red 164
, which is similar to Solvent Red 26 but with longer alkyl chains. The Internal Revenue Service
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.
Blue dyes are used for diesel designated for governmental and institutional vehicles, to detect theft.
, it has been a means of fund raising by illegal paramilitary organizations. In 2004, Northern Irish police discovered an illegal facility capable of removing the dye from 12 million litres of fuel 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 30m litres was discovered.
Dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....
s added to fuel
Fuel
Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...
s, 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".
The dyes used have to be soluble in the fuels they are added to and therefore in hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....
-based nonpolar solvents ("solvent dye
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 materials. Fuel dyes are one use of solvent dyes. Their...
s"). Red dyes are often various diazo dyes, e.g. Solvent Red 19, Solvent Red 24, and Solvent Red 26
Solvent Red 26
Solvent Red 26, also known as C.I. 26120, is a purplish red synthetic azo dye. Its chemical formula is C25H22N4O, or 1-Solvent Red 26, also known as C.I. 26120, is a purplish red synthetic [[azo dye]]. Its chemical formula is C25H22N4O, or 1-Solvent Red 26, also known as C.I. 26120, is a purplish...
. Anthraquinone dyes are used for green and blue shades, e.g. Solvent Green 33, Solvent Blue 35 and Solvent Blue 26.
It is advantageous to mix a liquid with a liquid instead of handling powdered dyes into a liquid.
The pure dyes found in modern liquid petroleum dyes are essentially 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 essentially 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 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 ultimately they are still lower cost per active molecule of dye chromphore than the modified forms. They have significant handling issues and health and safety issues that inherently arise from the handling of azo dyes (reds/yellows/green mixes).
Aviation gasoline
Avgas
Avgas is an aviation fuel used to power piston-engine aircraft. Avgas is distinguished from mogas , which is the everyday gasoline used in cars and some non-commercial light aircraft...
is dyed, both for tax reasons (avgas is typically taxed to support aviation infrastructure) as well as safety—there being obvious and disastrous consequences of fueling an aircraft with the wrong kind of fuel.
Fuel dye in the European Union
After August 2002, all European UnionEuropean Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
countries became obliged to add about 6 mg/L of Solvent Yellow 124
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...
, a dye with structure similar to Solvent Yellow 56, to all motor diesel fuel. This dye can be easily hydrolyzed with acids, splitting off the acetal
Acetal
An acetal is a molecule with two single-bonded oxygen atoms attached to the same carbon atom.Traditional usages distinguish ketals from acetals...
group responsible for its solubility in nonpolar solvents, and yielding a water-soluble form. Like a similar methyl orange
Methyl orange
Methyl orange is a pH indicator frequently used in titrations.It is often used in titrations because of its clear and distinct colour change. Because it changes colour at the pH of a mid-strength acid, it is usually used in titrations for acids...
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
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
, allowing detection of the red diesel added into motor diesel in amounts as low as 2-3%.
United Kingdom
In the United KingdomUnited Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, "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 than 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, highly unlikely in a metropolitan area but much more likely in a rural area. Unauthorized 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 SORN with the DVLA provided they are only used on private land. There is also no need to tax a vehicle that is not used on a public road.
Fuel dye in North America
In United States of America, the Environmental Protection AgencyUnited States Environmental Protection Agency
The U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
mandates use of a red dye to identify high-sulfur fuels for off-road use. Solvent Red 26
Solvent Red 26
Solvent Red 26, also known as C.I. 26120, is a purplish red synthetic azo dye. Its chemical formula is C25H22N4O, or 1-Solvent Red 26, also known as C.I. 26120, is a purplish red synthetic [[azo dye]]. Its chemical formula is C25H22N4O, or 1-Solvent Red 26, also known as C.I. 26120, is a purplish...
is used in the United States as a standard, though it is often replaced with Solvent Red 164
Solvent Red 164
Solvent Red 164, also called Oil Red B, is a synthetic red diazo dye. Its chemical structure is 1-Solvent Red 164, also called Oil Red B, is a synthetic red [[diazo dye]]. Its chemical structure is 1-...
, which is similar to Solvent Red 26 but with longer alkyl chains. The Internal Revenue Service
Internal Revenue Service
The Internal Revenue Service is the revenue service of the United States federal government. The agency is a bureau of the Department of the Treasury, and is under the immediate direction of the Commissioner of Internal Revenue...
mandates use of the same red dyes, in fivefold concentration, for tax-exempt diesel fuels such as 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...
; 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.
Blue dyes are used for diesel designated for governmental and institutional vehicles, to detect theft.
Fuel laundering
Processing fuel to remove the dye so it may be illicitly sold to motorists is a recognized criminal activity in the United Kingdom. In Northern IrelandNorthern Ireland
Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...
, it has been a means of fund raising by illegal paramilitary organizations. In 2004, Northern Irish police discovered an illegal facility capable of removing the dye from 12 million litres of fuel 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 30m litres was discovered.
Dyes used
Some dyes required in some countries are listed here:| Country | Fuel | Dye |
|---|---|---|
| Regular Unleaded Petrol | Purple Purple Purple is a range of hues of color occurring between red and blue, and is classified as a secondary color as the colors are required to create the shade.... (or Bronze Bronze Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and brittle, and it was particularly significant in antiquity, so much so that the Bronze Age was named after the metal... ) |
|
| Premium Unleaded Petrol | Yellow Yellow Yellow is the color evoked by light that stimulates both the L and M cone cells of the retina about equally, with no significant stimulation of the S cone cells. Light with a wavelength of 570–590 nm is yellow, as is light with a suitable mixture of red and green... |
|
| 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... |
any red dye | |
| Agricultural Fuel | red/purple dye | |
| Heating oil | any red dye | |
| 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... |
Furfural Furfural Furfural is an organic compound derived from a variety of agricultural byproducts, including corncobs, oat, wheat bran, and sawdust. The name furfural comes from the Latin word , meaning bran, referring to its usual source.... and Solvent Yellow 124 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... |
|
| Diesel for construction and agriculture | Furfural Furfural Furfural is an organic compound derived from a variety of agricultural byproducts, including corncobs, oat, wheat bran, and sawdust. The name furfural comes from the Latin word , meaning bran, referring to its usual source.... and Solvent Yellow 124 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... |
|
| Gas oil | Solvent Red 24 | |
| Marine diesel | Solvent Blue 35 | |
| 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... |
Automate Red NR or similar + Solvent Yellow 124 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... |
|
| Agricultural diesel | Automate Blue 8 GHF or similar + Solvent Yellow 124 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... |
|
| 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... |
Solvent Yellow 124 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... and similar |
|
| Heating oil | any red dye | |
| Marine diesel | any black dye | |
| Gas oil | green dye | |
| Kerosene Kerosene Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros... |
Solvent Red 19 and similar | |
| Heating oil | Solvent Red 161 | |
| Gas oil | Solvent Green 32 or 33 | |
| Agricultural diesel | any red dye and the additive Furfural Furfural Furfural is an organic compound derived from a variety of agricultural byproducts, including corncobs, oat, wheat bran, and sawdust. The name furfural comes from the Latin word , meaning bran, referring to its usual source.... |
|
| Agricultural diesel | any green dye | |
| Agricultural diesel | Solvent Blue 35 | |
| Heating oil | Solvent Red 19 and similar | |
| Agricultural diesel | any red dye | |
| Heating oil | any blue dye | |
| Heating oil | Solvent Blue 35, Solvent Blue 79, Solvent Blue 98 | |
| Gasoline 95 | yellow dye | |
| Gasoline 91 | red dye | |
| Gas oil ("Red Diesel") | Solvent Red 24, quinizarin | |
| Rebated kerosene Kerosene Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros... |
Coumarin Coumarin Coumarin is a fragrant chemical compound in the benzopyrone chemical class, found in many plants, notably in high concentration in the tonka bean , vanilla grass , sweet woodruff , mullein , sweet grass , cassia cinnamon and sweet clover... |
|
| many rebated | Solvent Yellow 124 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... ("Euromarker") |
|
| low-tax fuels, high-sulfur fuels | Solvent Red 26 Solvent Red 26 Solvent Red 26, also known as C.I. 26120, is a purplish red synthetic azo dye. Its chemical formula is C25H22N4O, or 1-Solvent Red 26, also known as C.I. 26120, is a purplish red synthetic [[azo dye]]. Its chemical formula is C25H22N4O, or 1-Solvent Red 26, also known as C.I. 26120, is a purplish... , Solvent Red 164 Solvent Red 164 Solvent Red 164, also called Oil Red B, is a synthetic red diazo dye. Its chemical structure is 1-Solvent Red 164, also called Oil Red B, is a synthetic red [[diazo dye]]. Its chemical structure is 1-... |
|
| Worldwide | Aviation gasoline 80/87 | red dye |
| Aviation gasoline 82UL | purple dye | |
| Aviation gasoline 100LL | blue dye | |
| Aviation gasoline 100/130 | green dye |