EP1310547A1 - Fuel with low sulphur content for diesel engines - Google Patents

Abstract

New motor diesel fuel with a S content less than 50 ppm, comprising mainly a middle distillate from a straight-run petroleum cut at 150 - 400 degrees C, and a small proportion of a lubricity additive containing mono-carboxylic and polycyclic acids. The additive content is at least 20 ppm, and consists of a combination of an aliphatic 12 - 24 C mono-carboxylic acid (optionally unsaturated) and a polycyclic hydrocarbon containing at least two rings of 5 - 6 atoms (of which one only may be N or O and the rest C). The two rings have 2C in common (preferably vicinal), are saturated or unsaturated, substituted or unsubstituted by at least one carboxylic, amine-, ester- or nitrile-carboxylate group. If the combination is tall oil, the fuel contains more than 60 ppm.

Description

The present invention relates to a fuel containing a creaminess additive to improve lubricating properties of fuels, whether diesel or aviation fuel (jet fuel), and more particularly of low-content diesel fuels in sulfur.

It is well known that diesel fuels and aviation fuels must have skills in lubrication for the protection of pumps, systems injection and all moving parts with which these products come into contact with in a internal combustion. With the desire to use products increasingly pure and non-polluting, especially devoid of sulfur, the refining industry was brought to improving their treatment processes more and more removal of sulfur compounds. However we observed that by losing the sulfur compounds we also lost the aromatic and polar compounds often associated, which caused a loss of the lubricating power of these fuels. Thus, below certain levels, the removal of sulfur compounds in the composition of these products very significantly promotes wear phenomena and rupture of moving parts at the pumps and injection systems. As the regulation of many countries imposed to limit the upper content acceptable as sulfur compounds in fuels at 0.05% by weight to reduce emissions from cars, trucks or buses with polluting combustion gases, particularly in urban agglomerations, it is necessary to replace these lubricating compounds by other non-polluting compounds with regard to the environment but presenting a power sufficient lubricant to avoid the risk of wear.

To solve this problem, several types additives have already been proposed. So we added to diesel fuel additives anti-wear, known for some in the field of lubricants, of the fatty acid ester type and unsaturated dimer fatty acids, amines aliphatics, esters of fatty acids and diethanolamine and long chain aliphatic monocarboxylic acids as described in US Patents 2,252,889, US 4,185,594, US 4,204,481, US 4,208,190, US 4,428,182. The most of these additives have a lubricating power sufficient but at concentrations too high which is very economically unfavorable to purchase. In addition, additives containing dimer acids, such as those containing trimer acids, cannot be used in fuels for vehicles in which the fuel may come into contact with lubrication because these acids form by chemical reaction deposits that are sometimes insoluble in oil, but above all incompatible with commonly used detergents.

US Patent 4,609,376 recommends the use anti-wear additives obtained from acid esters mono- and poly-carboxylic and polyhydric alcohols in fuels containing alcohols in their composition.

US Patent 2,686,713 recommends the introduction of tall oil up to 60 ppm in diesel fuels to prevent rust from forming on surfaces metal in contact with these fuels.

Another chosen route is to introduce esters vegetable oils or the vegetable oils themselves in these fuels to improve their lubricity or their smoothness. Among these are derivative esters rapeseed, linseed, soybean, sunflower or oils themselves (see patents EP 635,558 and EP 605,857). One of the major drawbacks of these esters is their low lubricity at a concentration of less than 0.5% by weight in fuels.

To improve the lubricating power of gas oils, patent application WO 95/33805 recommends the introduction of a cold-keeping additive consisting of nitrogenous additives comprising one or more NR ¹³ groups in which R ¹³ comprises from 12 to 24 atoms carbon, is linear, slightly branched or alicyclic and aromatic, the nitrogen group which can be linked by CO or CO ₂ and form amine carboxylates or amides.

The present invention aims to solve the problems encountered with the additives proposed by the prior art, that is to say to improve the lubricating power of desulfurized and flavored fuels, while remaining compatible with other additives, especially detergents, and lubricating oils, especially forming no deposits and reducing the cost, in particular by a lower additive content, well below 0.5%.

The present invention relates to a fuel for diesel engine, sulfur content less than 500 ppm comprising a major part of at least one middle distillate from a direct distillation cut of crude oil, temperatures between 150 and 400 ° C and part minor lubricant additive containing acids monocarboxylic and polycyclic, the said fuel being characterized in that it contains at least 20 ppm of the additive consisting of a combination of at least one saturated or monocarboxylic aliphatic hydrocarbon unsaturated, of linear chain between 12 and 24 atoms carbon, and at least one hydrocarbon compound polycyclic, containing at least two cycles each formed from 5 to 6 atoms of which one at most is possibly a heteroatom such as nitrogen or oxygen and the others are carbon atoms, these two rings also having two carbon atoms in common, preferably vicinal, these said cycles being saturated or unsaturated, unsubstituted or substituted by at least one group chosen from the group formed by carboxylic groups, carboxylates amine, esters and nitriles, the fuel containing more than 60 ppm additive when the said combination is tall oil.

We realized that the lubricating power provided by the oiliness additive containing such a combination is much higher than foreseeable by adding powers lubricants of each of its components taken separately. This unpredictable result reflects the synergistic effect of different components of the said combination with regard to the lubrication.

   avec X désignant les atomes de chaque cycle correspondant à 4 carbones, ou 3 carbones et un hétéroatome tel que l'azote ou l'oxygène, avec R₁, R₂, R₃ et R₄, identiques ou différents, désignant soit un atome d'hydrogène, soit des groupements hydrocarbonés, raccordés chacun à au moins un atome d'un des deux cycles, ces groupements hydrocarbonés étant choisis parmi les groupements alkyls constitués de 1 à 5 atomes de carbone, les groupements aryls, les cycles hydrocarbonés de 5 à 6 atomes, contenant éventuellement un hétéroatome tel que l'oxygène ou l'azote, chaque cycle étant formé par raccordement direct de deux groupements R_i choisis parmi R₁, R₂, R₃ et R₄, via éventuellement un hétéroatome, le dit cycle étant saturé ou insaturé, non substitué ou substitué par un radical aliphatique éventuellement oléfinique comprenant de 1 à 4 atomes de carbone, et Z est choisi dans le groupe constitué par les groupements carboxyliques, les carboxylates d'amines, les esters et les nitriles.According to a first embodiment of the fuel according to the invention, the polycyclic hydrocarbon compound of said combination is a hydrocarbon compound of formula (I) below:

with X designating the atoms of each cycle corresponding to 4 carbons, or 3 carbons and a heteroatom such as nitrogen or oxygen, with R ₁ , R ₂ , R ₃ and R ₄ , identical or different, designating either an atom of hydrogen, or hydrocarbon groups, each connected to at least one atom of one of the two rings, these hydrocarbon groups being chosen from alkyl groups consisting of 1 to 5 carbon atoms, aryl groups, hydrocarbon rings of 5 with 6 atoms, optionally containing a heteroatom such as oxygen or nitrogen, each cycle being formed by direct connection of two groups R _i chosen from R ₁ , R ₂ , R ₃ and R ₄ , optionally via a hetero atom, the said ring being saturated or unsaturated, unsubstituted or substituted by an optionally olefinic aliphatic radical comprising from 1 to 4 carbon atoms, and Z is chosen from the group consisting of carboxylic groups, carboxylate s of amines, esters and nitriles.

In a particular mode of this first mode of embodiment, the compound of formula (I) is chosen from group consisting of the natural resin acids obtained from the distillation residues of natural oils extracted from coniferous trees, especially conifers resinous, as well as amine carboxylates, esters and the nitriles of these acids.

Among the resin acids, the acid is preferred. abietic, dihydroabietic acid, acid tetrahydroabietic, dehydroabietic acid, acid neoabietic, pimaric acid, levopimaric acid and parastrinic acid and their derivatives.

   dans laquelle au plus un X de chaque cycle est un hétéroatome tel que l'azote ou l'oxygène, les autres X étant des atomes de carbone, dans laquelle R₁, R₂, R₃ et R_4, identiques ou différents, sont soit un atome d'hydrogène, soit des groupements hydrocarbonés, raccordés chacun à au moins un atome d'un des deux cycles, ces groupements hydrocarbonés étant choisis parmi les groupements alkyls comprenant de 1 à 5 atomes, les groupements aryls, les cycles hydrocarbonés de 5 à 6 atomes, contenant éventuellement un hétéroatome tel que l'oxygène ou l'azote, chaque cycle étant formé par raccordement direct de deux groupements R_i choisis parmi R₁, R₂, R₃ et R₄, via éventuellement un hétéroatome, le dit cycle étant saturé ou insaturé, non substitué ou substitué par un radical aliphatique éventuellement oléfinique comprenant de 1 à 4 atomes de carbone, et Z, raccordé à au moins un atome d'au moins un des deux cycles, est choisi dans le groupe constitué par les groupements carboxyliques, carboxylates d'amines, les esters et les nitriles.In a second embodiment of the invention, the polycyclic hydrocarbon compound of said combination is a hydrocarbon compound of formula (II) below;

in which at most one X in each cycle is a heteroatom such as nitrogen or oxygen, the other X being carbon atoms, in which R ₁ , R ₂ , R ₃ and R _4, identical or different, are either a hydrogen atom or hydrocarbon groups, each connected to at least one atom from one of the two rings, these hydrocarbon groups being chosen from alkyl groups comprising from 1 to 5 atoms, aryl groups, hydrocarbon rings of 5 to 6 atoms, optionally containing a heteroatom such as oxygen or nitrogen, each ring being formed by direct connection of two groups R _i chosen from R ₁ , R ₂ , R ₃ and R ₄ , optionally via a hetero atom, the said ring being saturated or unsaturated, unsubstituted or substituted by an optionally olefinic aliphatic radical comprising from 1 to 4 carbon atoms, and Z, connected to at least one atom from at least one of the two rings, is chosen from the group constitute by carboxylic groups, carboxylates, amines, esters and nitriles.

According to the invention, the aliphatic hydrocarbon monocarboxylic is in the form of acid, carboxylate amines and esters.

In a more advanced mode of the invention, the combination comprises from 1 to 50% by weight of at least one compound corresponding to at least one of the formulas (I) and (II), and from 50 to 99% by weight of at least one acid linear monocarboxylic, saturated or unsaturated, comprising 12 to 24 carbon atoms, these products being present under form of acid, carboxylate of amines or esters.

By amine carboxylates is meant the compounds resulting from the reaction of these acids with amines or primary, secondary and tertiary polyamines including from 1 to 8 carbon atoms per chain and the alkylene amines and primary, secondary or tertiary alkylene polyamines comprising from 2 to 8 carbon atoms. In a preferred mode of the invention, these amine salts are derived from selected amines in the group consisting of ethyl-2-hexylamine, N, N-dibutylamine, ethylenediamine, diethylenetriamine and tetraethylenepentamine.

Among the esters, alkanol esters are preferred primary with 1 to 8 carbon atoms or polyalcohols from the group consisting of ethylene glycol, propylene glycol, glycerol, trimethylolpropane, pentaerythritol, diethanolamine, triethanolamine and their derivatives.

In a preferred embodiment of the invention, the fuel contains 50 to 1000 ppm of the oiliness additive.

According to the present invention, one can add to the said fuel at least one additive from the group of additives usually added in such fuels such as detergent additives, additives improving the index of cetane, demulsifying additives, anti-corrosion additives, additives improving cold coming, and odor modifying additives.

To explain the advantages of this invention with regard to the prior art, examples are given below by way of illustration but not limiting of the scope of the claimed invention.

EXAMPLE I

This example describes the choice of additives in function of their solubility in a weak diesel sulfur.

Each additive in test is diluted to 5% by weight in a diesel (GO) at 500 ppm sulfur, at room temperature.

The additives according to the invention are designated by Y and by C the comparative examples in Table I below. Additives Y consist, on the one hand, of a mixture of a combination of fatty acids containing by weight 50 to 55% oleic acid, 30 to 40% linoleic acid, 3 to 5% palmitic acid and 1 with 2% linolenic acid, and for another part in resin acids obtained by distillation of tall oil, by-product of the manufacture of wood pulp by the sulphate process. For the comparative examples, C ₁ corresponds to pure oleic acid, C ₂ to rosin which is a mixture of resin acids corresponding to the distillation residue of pine gems and C ₃ is a mixture of dimer acids obtained by thermal dimerization and / or catalytic of unsaturated fatty acids. Additive % Fatty acids % resin acids solubility in GO Y ₁ 70 30 soluble Y ₂ 85 15 soluble Y ₃ 98 2 soluble C ₁ 100 0 soluble C ₂ 0 100 very cloudy K ₃ 0 0 soluble

It can be seen from this table that, with the exception of resin acids (C ₂ ), all of these compounds are very soluble in diesel.

EXAMPLE II

This example studies the lubricating power of additives described in Example I.

The lubricity of these additives has been measured under the conditions of the HFRR test (High Frequency Reciprocating Rig) as described in article SAE 932692 by J.W. HADLEY of the University of Liverpool.

The test consists in imposing jointly with a ball of steel in contact with a stationary metal plate, a pressure corresponding to a weight of 200 g and a displacement alternating 1 mm at a frequency of 50 Hz. The ball in movement is lubricated by the composition to be tested. The temperature is maintained at 60 ° C for the duration of the test, i.e. 75 min. The lubricity is expressed as the average value of the footprint diameters wear of the ball on the plate. A small diameter wear (generally less than 400µm) indicates good lubricity; conversely, a wear diameter important (greater than 400µm) translates a power of as much more insufficient than the value of the wear diameter is high.

The lubricating power of the additives was measured on a gas oil identical to that of Example I, each tested sample containing only 100 ppm of additive. The results are given in Table II below. Sample Wear diameter (µm) Diesel only (GO) 510 GO + Y ₁ 350 GO + Y ₂ 385 GO + Y ₃ 410 GO + C ₁ 440 GO + C ₂ 470 GO + C ₃ 380

This table shows that the additives (Y ₁ and Y ₂ ) according to the invention have an identical effect if not better than the dimer acids (C ₃ ). In addition, it is found that the mixture of fatty acids with resin acids has a much better lubricating power than those obtained with these same compounds taken separately, translating a synergy of these components between them.

EXAMPLE III

This example studies the compatibility of additives described in Example I with lubricants usually used in diesel engines according to the protocol described below.

70 ml of engine oil with total basicity equal to 15 mg of KOH per gram are mixed with 700 ml of diesel at 500 ppm of sulfur identical to that of Example I, in which is added 35 g of additive. Each mixture as well constituted is placed in an oven at 50 ° C, then evaluated visually the presence or absence of deposits, a precipitate or disorder resulting from incompatibility between so-called "oiliness" additives sufficient lubricant, with an engine lubricant called KM2 + marketed by the company of Huiles Renault Diesel.

The compatibility results are collated in Table III below. Additive Compatibility with lubricant Y ₁ No deposit - clear solution Y ₂ No deposit - clear solution Y ₃ No deposit - very light veil C ₁ Very slight cloudiness after 48 hours C ₂ Presence of some insolubles K ₃ Formation of a disorder upon addition of additive GO

The additives of the invention, Y ₁ and Y ₂ give no deposit or cloudiness when the diesel fuel with 100 ppm additive is added to the oil.

EXAMPLE IV

The purpose of this example is to describe additives oiliness adapted to be introduced into fuels according to the invention.

These are, on the one hand, esters obtained by reacting alcohols with the additive Y ₁ of Example I in an equimolar mixture, in maintaining this mixture at reflux between 130 and 150 ° C. under atmospheric pressure, then in distilling l water / toluene azeotrope.

On the other hand, they are amine carboxylates obtained by simple mixing at room temperature and at atmospheric pressure of Y ₁ with an amine or polyamine according to the invention, thus allowing the neutralization of the carboxylic sites.

These additives are introduced into a diesel such as described in Example II at a concentration of 100 ppm.

Table IV collates below the results of the wear test described in Example II obtained with the diesel fuel thus doped to characterize their lubricating power. Nature of the additive (Y1 + ..) Wear diameter (µm) triethanolamine 365 N, N dimethylethanolamine 375 ethylene glycol 385 glycerol 360 propylene glycol 380 ethyl-2-hexanol 385 N, N-dimethyl-1,3-propanediamine 360 ethyl-2-hexylamine 370 N, N-dibutylamine 375 ethylenediamine 355

From these results, it is confirmed that the fuels doped with such additives according to the invention have good lubricity.

Claims (12)

Fuel for a diesel engine, with a sulfur content of less than 500 ppm comprising a major part of at least one middle distillate obtained from a direct distillation cut of crude oil, with temperatures between 150 and 400 ° C and a minor part d a lubricity additive containing monocarboxylic and polycyclic acids, the said fuel being characterized in that it contains at least 20 ppm of the additive consisting of a combination of at least one aliphatic monocarboxylic hydrocarbon, saturated or unsaturated, linear chain of between 12 and 24 carbon atoms, and at least one polycyclic hydrocarbon compound, containing at least two rings each formed from 5 to 6 atoms, at most one of which is optionally a heteroatom such as nitrogen or oxygen and the others are carbon atoms, these two rings also having two carbon atoms in common, preferably vicinal, these said rings being saturated or unsaturated, non-substituted s or substituted by at least one group chosen from carboxylic groups, carboxylates, amine, esters and nitriles, more than 60 ppm fuel containing the additive when the said combination is tall oil. Fuel according to claim 1 characterized in that the polycyclic hydrocarbon compound of said combination is a hydrocarbon compound of formula (I) below;

with X designating the atoms of each cycle corresponding to 4 carbons, or 3 carbons and a heteroatom such as nitrogen or oxygen, with R ₁ , R ₂ , R ₃ and R ₄ , identical or different, designating either an atom of hydrogen, or hydrocarbon groups, each connected to at least one atom of one of the two rings, these hydrocarbon groups being chosen from alkyl groups consisting of 1 to 5 carbon atoms, aryl groups, hydrocarbon rings of 5 with 6 atoms, optionally containing a heteroatom such as oxygen or nitrogen, each cycle being formed by direct connection of two groups R _i chosen from R ₁ , R ₂ , R ₃ and R ₄ , optionally via a hetero atom, the said ring being saturated or unsaturated, unsubstituted or substituted by an optionally olefinic aliphatic radical comprising from 1 to 4 carbon atoms, and Z is chosen from the group consisting of carboxylic groups, carboxylates of amines, esters and nitriles. Fuel according to one of claims 1 and 2
characterized in that the compound of formula (I) is chosen from the group consisting of natural resin acids obtained from the distillation residues of natural oils extracted from resinous trees, in particular resinous conifers, amine carboxylates, and ester and nitrile derivatives of these acids. Fuel according to one of claims 1 to 3
characterized in that the resin acids are chosen from the group consisting of abietic acid, dihydroabietic acid, tetrahydroabietic acid, dehydroabietic acid, neoabietic acid, pimaric acid, levopimaric acid, l parastrinic acid and their derivatives. Fuel according to claim 1 characterized in that the polycyclic hydrocarbon compound is a hydrocarbon compound of formula (II) below:

in which at most one X of each cycle is a heteroatom such as nitrogen or oxygen, the other X being carbon atoms, in which R ₁ , R ₂ , R ₃ and R ₄ , identical or different, correspond to a hydrogen atom or to hydrocarbon groups, each connected to at least one atom from one of the two rings, these hydrocarbon groups being chosen from alkyl groups comprising from 1 to 5 atoms, aryl groups, hydrocarbon rings of 5 to 6 atoms, optionally containing a heteroatom such as oxygen or nitrogen, each ring being formed by direct connection of two groups R _i chosen from R ₁ , R ₂ , R ₃ and R ₄ , optionally via a hetero atom, the said ring being saturated or unsaturated, unsubstituted or substituted by an optionally olefinic aliphatic radical comprising from 1 to 4 carbon atoms, and Z, connected to at least one atom from at least one of the two rings, is chosen from the group vs formed by carboxylic groups, carboxylates of amines, esters and nitriles. Fuel according to one of claims 1 to 5
characterized in that the monocarboxylic aliphatic hydrocarbon is in the form of acid, amine carboxylate and / or esters. Fuel according to one of claims 1 to 6
characterized in that it comprises from 1 to 50% by weight of at least one compound corresponding to at least one of formulas (I) and (II), and from 50 to 99% by weight of at least one aliphatic hydrocarbon linear monocarboxylic, saturated or unsaturated, comprising from 12 to 24 carbon atoms. Fuel according to one of claims 1 to 7
characterized in that the amine carboxylates result from the reaction of these acids with primary, secondary and tertiary amines or polyamines comprising from 1 to 8 carbon atoms per chain and the primary, secondary, or tertiary alkyleneamines and alkylene polyamines comprising from 2 to 8 carbon atoms. Fuel according to Claim 8, characterized in that the amines from which the amine carboxylates are derived are chosen from the group consisting of ethyl-2-hexylamine, N, N-dibutylamine, ethylenediamine, diethylenetriamine and tetraethylenepentamine. Fuel according to one of claims 1 to 7
characterized in that the esters result from the reaction of these acids with alcohols from the group consisting of primary alcohols comprising from 1 to 8 carbon atoms and polyalcohols of the ethylene glycol, propylene glycol, glycerol, trimethylolpropane, pentaerythritol, diethanolamine and triethanolamine type. Fuel according to one of claims 1 to 10
characterized in that it contains from 50 to 1000 ppm of a lubricity additive. Fuel according to one of claims 1 to 11
characterized in that it additionally contains at least one additive from the group of additives usually added in such fuels such as detergent additives, additives improving the cetane number, demulsifying additives, anti-corrosion additives, additives improving cold coming, and odor modifying additives.