Fuel and related compositions – Liquid fuels – Containing organic -c
Reexamination Certificate
2001-11-16
2003-08-26
Medley, Margaret (Department: 1714)
Fuel and related compositions
Liquid fuels
Containing organic -c
C044S404000, C044S403000, C044S412000
Reexamination Certificate
active
06610111
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to mixtures of fatty acids and paraffin dispersants of improved low-temperature stability, and to their use for improving the lubricity of middle-distillate fuel oils.
FIELD OF THE INVENTION
Mineral oils and mineral-oil distillates which are used as fuel oils generally comprise 0.5% by weight or more of sulfur, which causes the formation of sulfur dioxide on combustion. In order to reduce the resultant environmental pollution, the sulfur content of fuel oils is constantly being reduced further. The EN 590 standard, which relates to diesel fuels, currently prescribes a maximum sulfur content of 350 ppm in Germany. In Scandinavia, fuel oils containing less than 50 ppm and in exceptional cases less than 10 ppm of sulfur are already in use. These fuel oils are generally produced by subjecting the fractions obtained from crude oil by distillation to reductive refining. During desulfurization, however, other substances are also removed which give the fuel oils a natural lubricity. These substances include, inter alia, polyaromatic and polar compounds.
However, it has now been found that the friction- and wear-reducing properties of fuel oils become worse with increasing degree of desulfurization. These properties are frequently so unsatisfactory that corrosion phenomena must be expected after only a short time on the materials lubricated by the fuel, such as, for example, distributor injection pumps of diesel engines. The maximum value for a 95% distillation point of a maximum of 360° C. which has been prescribed in EN 590 since the year 2000 and the further reduction in the 95% distillation point to below 360° C. and in some cases below 330° C. which has in the meantime been effected in Scandinavia intensify these problems further.
DESCRIPTION OF THE RELATED ART
The prior art has therefore described approaches which are intended to represent a solution to this problem (so-called lubricity additives).
EP-A-0 798 364 discloses salts and amides of mono- to tetracarboxylic acids having from 2 to 50 carbon atoms and aliphatic mono/polyamines having from 2 to 50 carbon atoms and from 1 to 10 nitrogen atoms as lubricity additives for low-sulfur diesel fuel. Preferred amines have 8-20 carbon atoms, such as, for example, coconut fatty amine, tallow fatty amine and oleylamine.
WO-A-95/33805 discloses the use of cold-flow improvers for improving the lubricity of low-sulfur middle distillates. The suitable substances mentioned include polar nitrogen-containing compounds which contain an NR
13
group, where R
13
is a hydrocarbon radical having from 8 to 40 carbon atoms, and may be in the form of a cation.
WO-A-96/18706 discloses, analogously to WO-A-95/33805, the use of the nitrogen-containing compounds mentioned therein in combination with lubricity additives.
WO-A-96123855 discloses, analogously to WO-A-95/33805, the use of the nitrogen-containing compounds mentioned therein in combination with detergent additives.
The fatty acids used in accordance with the prior art have the disadvantage that they solidify on storage at low temperatures, i.e. often at room temperature, usually at temperatures of from 0° C. to at the latest −5° C., or deposit crystalline fractions and cause problems in handling. This problem can only be partially solved even by dilution with organic solvents, since fractions also crystallize from these solutions or the solution gels and solidifies. For use as lubricity additives, they therefore have to be diluted to a great extent or stored in heated storage containers and dispensed via heated lines.
The effectiveness of cold-flow improvers as lubricity additives is alone not sufficient, which means that either very high dispensing rates or synergists have to be employed.
SUMMARY OF THE INVENTION
The object on which the present invention is based was to find lubricity additives which improve the lubricity of middle distillates at reduced dispensing rates, but remain homogeneous, clear and in particular flowable even at low temperatures.
It has been found that mixtures of fatty acids with polar nitrogen-containing compounds which are effective as paraffin dispersants in middle distillates remain flowable and clear for an extended time even at significantly reduced temperatures, in some cases down to below −20° C., in particular cases down to below −30° C. and in special cases down to below −40° C., and in addition improve the lubricity of middle distillates more efficiently than pure fatty acids of the prior art.
The invention thus relates to low-temperature-stabilized additives for fuel oils having a sulfur content of up to 0.05% by weight, comprising fatty acid mixtures of
A1) from 1 to 99% by weight of at least one saturated mono- or dicarboxylic acid having from 6 to 50 carbon atoms,
A2) from 1 to 99% by weight of at least one unsaturated mono- or dicarboxylic acid having from 6 to 50 carbon atoms, and
at least one polar nitrogen-containing compound which is effective as paraffin dispersant in middle distillates in an amount of from 0.01 to 90% by weight, based on the total weight of A1), A2) and B).
DETAILED DESCRIPTION OF THE INVENTION
The invention furthermore relates to low-temperature-stabilized solutions of the additives according to the invention in organic solvents, where the solutions comprise from 1 to 90% by weight of solvent. Suitable solvents are aliphatic and/or aromatic hydrocarbons or hydrocarbon mixtures. The additives according to the invention preferably comprise 1-80%, especially 10-70%, in particular 25-60%, of solvent. The low-temperature-stabilized solutions according to the invention have a pour point of below −40° C., preferably −45° C., in particular −50° C.
The invention furthermore relates to low-temperature-stabilized fatty acid mixtures of
A1) from 1 to 99% by weight of at least one saturated mono- or dicarboxylic acid having from 6 to 50 carbon atoms,
A2) from 1 to 99% by weight of at least one unsaturated mono- or dicarboxylic acid having from 6 to 50 carbon atoms, and
at least one polar nitrogen-containing compound which is effective as paraffin dispersant in middle distillates, in an amount of from 0.01 to 90% by weight, based on the total weight of A1), A2) and B).
The invention furthermore relates to fuel oils comprising, besides a middle distillate having a sulfur content of up to 0.05% by weight, fatty acid mixtures of
A1) from 1 to 99% by weight of at least one saturated mono- or dicarboxylic acid having from 6 to 50 carbon atoms,
A2) from 1 to 99% by weight of at least one unsaturated mono- or dicarboxylic acid having from 6 to 50 carbon atoms, and
at least one polar nitrogen-containing compound which is effective as paraffin dispersant in middle distillates, in an amount of from 0.01 to 90% by weight, based on the total weight of A1), A2) and B).
The invention furthermore relates to the use of said mixtures comprising constituents A and B for improving the lubrication properties of low-sulfur middle distillates having a sulfur content of up to 0.05% by weight.
Preferred fatty acids (constituent A) are those having 8-40 carbon atoms, in particular 12-22 carbon atoms. The alkyl radicals in the fatty acids essentially consist of carbon and hydrogen. However, they may carry further substituents, such as, for example, hydroxyl, halogen, amino or nitro groups, so long as these do not impair the predominant hydrocarbon character.
Constituent A2) may contain one or more double bonds and be of natural or synthetic origin. In the case of polyunsaturated carboxylic acids, their double bonds may be isolated or conjugated. The proportion of saturated fatty acids A1) in the mixture of A1) and A2) is preferably less than 20% by weight, in particular less than 10% by weight, especially less than 5% by weight. In preferred fatty acid mixtures, which is taken to mean the combination of A1) and A2) here, at least 50% by weight, in particular at least 75% by weight, especially at least 90% by weight, of the constituents contain one or more double bond
Krull Matthias
Reimann Werner
Clariant GmbH
Medley Margaret
Silverman Richard P.
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