EP0826765A1 - Compositions of additives improving the lubricating capacity of motor fuels and motor fuels containing the same - Google Patents

Abstract

Additive compositions used in petroleum middle distillates comprise at least one partial ester formed from a polyol and a 4-24C monocarboxylic acid. Also claimed, are fuel compositions incorporating such additives, with improved lubricating properties.

Description

The present invention relates to additive compositions which, when added to various refined petroleum cuts improve their lubricating power.

These cups constitute what is usually referred to as "middle distillates". They can be used as fuel bases for engines jet, gas turbines, or diesel engines of all kinds. They characterized by the fact that they consist mainly of hydrocarbons and that their distillation range at atmospheric pressure is between about 130 ° C and about 400 ° C.

The term "middle distillates" thus designates, in addition to distillation cuts direct, possible mixtures of such cuts with cuts resulting from thermal, catalytic or steam cracking, including hydrogenating cracking.

In jet fuels, the severity of refining required to obtain a improvement of product characteristics (reduced aromatic and olefins, very low metal contents, very low cloud point and absence of sulfur active) results in significant wear of the mechanical components in contact with the fuel, in particular pumps supplying fuel to the reactor.

In gas turbines and diesel engines, the gradual severity of legislation aimed at combating the increase in air pollution translated, for several years already, by the introduction in greater proportion of fuels from conversion, in particular from processes using hydrogen as conversion agent. As a result, the anti-wear protections of natural origin that the direct distillation fuels traditionally contained are reduced, or even completely eliminated in the case of diesel from Nordic countries meeting the Swedish specification "City Fuel Class 1".

The compositions proposed within the framework of the present invention are intended to combat the insufficiency of the wear protection of fuels which have just been described previously. These compositions make it possible in particular to confer gas oils, which originally lacked antiwear properties natural, sufficient anti-wear power to ensure, in service, functioning without incident on the injection organs.

The invention therefore provides an additive composition which can be used to increase the lubricating power of middle petroleum distillates, characterized in that it comprises at least one partial ester formed between at least one polyol and at least one monocarboxylic acid from 4 to 24 carbon atoms, said carboxylic acid possibly being linear or branched, saturated, monounsaturated or polyunsaturated, possibly hydroxylated or isomerized (as is the case for isostearic acids).

The polyols considered in the definition of partial esters used as additives in the context of the invention are mainly propanediol-1,2 (or mono-propylene glycol), propanediol-1,3, butanediol-1,3, butanediol-1,4, neopentyl-glycol, glycerin (or glycerol), diglycerol, polyglycerols, trimethylol-propane and pentaerythritol.

The main monocarboxylic acids considered are acids linear or weakly branched aliphatics, generally referred to as "fatty acids", which can be chosen for example from butyric, caproic, caprylic acids, capric, lauric, myristic, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, ricinoleic, arachidic, gadoleic, behenic, erucic and lignoceric, as well as mixtures of isostearic acid isomers.

The compositions of the invention are more particularly considered partial esters formed between glycerol and the fatty acids defined above and, among these, diglycerides-1,2 and / or 1,3, alone or in mixtures with mono-glycerides-1 and / or 2, as well as, and preferably, monoglycerides-1 and / or 2 do not containing only traces of 1,2 and / or 1,3 diglycerides.

où -R = [-(CH₂)_n - A - (CH₂)_m- CH₃ ].The general formula of mono and diglycerides can be represented as follows:

where - R = [- (CH ₂ ) _n - A - (CH ₂ ) _m - CH ₃ ].

When A = - CH ₂ -, we can have n = 1, with m = 0, 2, 4, 6, 8, 10, 12, 14, 16, 18 or 20.

on peut avoir n = 7, avec m = 3,5,7,9 ; ou n = 11, avec m = 7.When A =

we can have n = 7, with m = 3,5,7,9; or n = 11, with m = 7.

on peut avoir n = 7, avec m = 4.When A =

we can have n = 7, with m = 4.

on peut avoir n = 7 et m = 1. When A =

we can have n = 7 and m = 1.

on peut avoir n = 7, avec m = 5.When A =

we can have n = 7, with m = 5.

There are described in the prior art various methods of manufacturing monoglycerides and mixtures of mono and diglycerides.

Monoglycerides can be obtained very selectively by the enzymatic; in this case, the formation of monoglyceride-1 or of monoglyceride-2, as described for example in the communication by M. Leclerc: "Novo Nordisk Bioindustrie S.A.", at the Chevreul Days in Toulouse-1990. The enzymatic formation of monoglycerides, in this case monoglycerides-1, is also described by B. Steffen et al. in: "Fat Sci. Technology" 97th year n ° 4 (1995) pp 132-136.

The monoglycerides can also be obtained from glycidol and fatty acids, for example according to European patent EP-B-0 545 477, or, in a more general, using thermal or basic catalysis.

The synthesis of monoglycerides in admixture with diglycerides is described for example in patent US-A-2,634,279. This patent mentions as an example the heating at a temperature of 250-260 ° C. of 2.3 moles of glycerin with 1 mole triglyceride expressed as fatty acid. This type of reaction is catalyzed by a base, such as for example LiOH, NaOH, KOH, CaO or Ca (OH) ₂ . This results in a mixture of mono and diglycerides, the monoglyceride content of which can reach approximately 60%.

To obtain monoglycerides with 90 - 94% purity, the molecular distillation of the mixture obtained previously, for example according to the method described by W. Fischer in: "Fette Seifen Anstrichmittel" 83.Jahrgang - Sonderheft (1981).

The main impurities encountered in such a preparation method of monoglycerides are traces of free glycerin, diglycerides, triglycerides and free fatty acids.

In the context of the present invention, more particularly the partial esters of glycerol (glycerin), i.e. monoglycerides, diglycerides and mixtures of mono and diglycerides, but we can also consider partial esters of other polyols, or partial esters of glycerol and at least one other polyol in blends.

The monoglycerides and diglycerides considered in the additive compositions of the invention can be derived from the partial esterification of glycerol with free fatty acids (saturated, monounsaturated or polyunsaturated fatty acids, preferably containing from 8 to 24 carbon atoms and originating for example from the hydrolysis of natural oils, vegetable or animal), used pure or in mixtures; they can also be derived from the transesterification of C ₁ to C ₄ alcohol esters of these same fatty acids, with glycerol (glycerolysis); they can finally result directly from the transesterification by glycerol of the natural oils themselves, containing these fatty acids linked to glycerol in the form of triglycerides.

Although, for the preparation of monoglycerides (or diglycerides), using the same oil or mixture of fatty acids gives the same quality of product if we use the same stoichiometry of glycerin with the number total fatty acids, the preferred method of preparation is from oils themselves, which are transesterified by reaction with glycerin additional.

For the partial esters of other polyols, it will be preferable to start from an acid fatty or a mixture of fatty acids, unless it is desired to form mixtures of esters partial glycerol and at least one other polyol, in which case the method of obtaining preferred will also be the transesterification of a natural oil, using this polyol alone or a mixture in appropriate proportions of this polyol with glycerin.

Natural oils and fats that can be used as a base synthesis in the methods of preparation of partial esters by transesterification are very varied. Mention may be made, for example, of oils from copra, babassu, palm kernel, tucum, murumuru and palm, lard, tallow, melted butter, shea, olive, peanut, kapok, bitter date, papaya, coloquinte, croton, nutmeg, purge, hemp, beech, hibiscus, pulghere, camelina, safflower, niger, sunflower, oleic sunflower, rubber, coconut, purga, nut, corn, soy, cotton, sorghum, seed grapes, flax, tobacco, common pine, afzellia, cabbage turnip, mustard, brown mustard, Chinese wood, bancoulier, aleurite, amoora, fir, cramble, perilla, erucic rapeseed, new rapeseed, oleic rapeseed, sesame, cocoa butter, tall oil, castor oil and wheat germ.

The conditions for preparing the partial polyol esters according to the invention are classic conditions. The polyol (s) are used in excess relative to the stoichiometry of the partial esters that one wishes to prepare. So, to prepare mono or diglycerides, 3 to 9 moles of glycerol per mole of acid can be used free fat or per mole of fatty acid contained in the starting triglyceride and one operates for example at temperatures from 180 to 250 ° C.

As already indicated above, the oil cuts to which to be added the compositions of the invention are generally middle distillates of petroleum, such as, for example, those which serve as a basis for diesel fuels (diesel) or for fuels for land, sea or aviation turbines. They are characterized by the fact that they consist mainly of hydrocarbons and that their distillation range at atmospheric pressure is between about 130 ° C and about 400 ° C.

The incorporation rate of the partial polyol esters to be introduced into the middle distillates according to the invention is generally between 50 and 2000 and preferably between 75 and 200 ppm.

The following examples illustrate the invention.

EXAMPLES

We first describe the preparation of the partial esters that will be used as additive compositions for middle distillates.

In these examples, the monoglycerides and diglycerides were synthesized in laboratory according to known protocols using sodium hydroxide as catalyst, from rapeseed oil (Products A and C) and oleic sunflower oil (Products B and D) and glycerin (Products A, B and C) or a mixture of glycerin and 1,3-propanediol (Product D).

The distribution of fatty acids included in the composition of rapeseed and oleic sunflower oils which were used for the synthesis of monoglycerides and diglycerides is shown in Table 1. Fatty acid content expressed in% by weight Fatty acids Colza oil Oleic sunflower oil - palmitic C16: 0 5.20 3.90 - palmitoleic C16: 1 0.30 - - stearic C18: 0 1.60 4.00 - oleic C18: 1 59.30 79.90 - linoleic C18: 2 21.35 10.40 - linolenic C18: 3 9.90 0.15 - peanut C20: 0 0.55 0.30 - gadoleic C20: 1 1.10 0.25 - behenic C22: 0 0.20 0.80 - erucic C22: 1 0.50 - - lignoceric C24: 0 - 0.30

PREPARATIONS A and B

The degree of purity of these products was determined by chromatography in gas phase after silylation of the sample. For rapeseed and oleic sunflower (products A and B), an average purity of monoglycerides is obtained (1 + 2) between 92.5 and 93% by weight. About 6% of diglycerides remain (1.2 + 1.3) and of the order of 1% of free fatty acids.

PREPARATION C

The diglyceride derived from rapeseed oil (product C) has an approximate content of 62% diglycerides (1.2 + 1.3), 37% in monoglycerides (1 + 2) and approximately 1% in weight Fatty acids.

PREPARATION D

2 moles of 1,3-propanediol are heated with 0.5 mole equivalent of oleic sunflower in the presence of 2 g of sodium hydroxide at a temperature of 220 ° C. After 2 reaction hours 30 minutes, a mixture of mono and diesters of propanediol-1,3 and mono and diglycerides. The total content of the mixture obtained in monoesters of 1,3-propanediol and monoglycerides is approximately 55% by weight, the remainder consisting of 1,3-propanediol diester, diglycerides as well as a minimal fraction of unconverted triglycerides (<2% by weight).

Before their use, the products manufactured as described above are subjected to purification by washing with water in the presence of n-heptane, then evaporation of the n-heptane, in order to completely eliminate the catalyst and the excess polyol.

In the following examples, the tests carried out with the partial esters are described. obtained as described above.

The antiwear properties of the compounds A, B, C and D of the invention were measured by means of the device known by the acronym HFRR (High Frequency Reciprocating Rig).

The test procedure on this tribometer is defined by CEC (Coordinating European Council - European body common to the automotive professions and of Petroleum) under the reference CEC F-06-T-94. It is being standardized by ISO (International Standard Organization) under the reference ISO / DIS 12156.

In this procedure, the anti-wear power of diesel oils is estimated through measuring the wear of a 6 mm diameter ball made of hardened, rubbing 100Cr6 steel reciprocating on a polished 100Cr6 steel top. The set of two test tubes test tank is bathed in diesel fuel to be tested.

A heating system keeps the rooms at 60 ° C, this temperature being very representative of the actual operating conditions of a diesel injection pump on vehicle. A mass of 200 g presses the ball against the plane during the movement.

This is done at the frequency of 100 Hz, with a range of motion 1 mm.

During the reciprocating movement generated by the tribometer, a cap of the ball is worn. The diameter measured under the light microscope of this cap, expressed in micrometers, the greater the wear resistance of the product tested is weak. It is accepted by the manufacturers of injection pumps for Diesel engines, that, in this test, a wear diameter of less than 400 µm is a guarantee of trouble-free operation in real service.

The diesel fuel used to carry out the HFRR tests has the composition indicated in Table 2 below. Measured properties Methods Values initial point of distillation NF M 07-002 213 ° C point at 50% NF M 07-002 270 ° C distillation end point NF M 07-002 312 ° C Density at 20 ° C NF T 60-172 803 kg / m ³ kinematic viscosity at 20 ° C NF T 60-100 4.31 mm ² / s sulfur content ASTM D 3120 <1 mg / l water content NF T 60-154 17 mg / l pour point NF T 60-105 - 42 ° C cloud point NF T 60-105 - 27 ° C

EXAMPLE 1

We present in this example an HFRR test carried out according to the procedure previously described using product A (rapeseed oil monoglyceride) in dilution in diesel to contents of 50, 125, 250 and 500 ppm by mass.

The test is also carried out with pure diesel fuel without additives.

The wear values are listed in table 3 below. Fuel composition diameter of the worn cap
expressed in µm Diesel additives free 600 Diesel 50 ppm of product A 600 Diesel 125 ppm of product A 268 Diesel 250 ppm of product A 262 Diesel 500 ppm of product A 210

All the values obtained are the average of the results from several determinations.

Performance review shows that a concentration of around 125 parts per million is enough to give a diesel completely devoid of wear protection natural, sufficient anti-wear power to ensure operation, operation injection device incidents.

EXAMPLE 2

We present in this example an HFRR test carried out according to the procedure previously described using product B (sunflower oil monoglyceride oleic) diluted in diesel to levels of 50, 125, 250 and 500 ppm (parts per million by mass).

The test is also carried out with pure diesel fuel without additives.

The wear values are listed in table 4 below. Fuel composition diameter of the worn cap
expressed in µm Diesel additives free 600 Diesel 50 ppm of product B 600 Diesel 125 ppm of product B 354 Diesel 250 ppm of product B 254 Diesel 500 ppm of product B 209

All the values obtained are the average of the results from several determinations.

As before, the performance review shows that a concentration of around 125 parts per million is enough to give a completely diesel lacking natural anti-wear protections, sufficient anti-wear power to ensure in service, trouble-free operation of the injection devices.

EXAMPLE 3

We present in this example an HFRR test carried out according to the procedure described previously using product C (raplyceride oil diglyceride) in dilution in diesel to contents of 125 and 250 ppm by mass.

The test is also carried out with pure diesel fuel without additives.

The wear values are listed in table 5 below. Fuel composition diameter of the worn cap
expressed in µm Diesel additives free 600 Diesel 125 ppm of product C 405 Diesel 250 ppm of product C 190

The above values reflect the average of the results obtained over several test trials.

As before, the performance review shows that a concentration of around 125 parts per million is enough to give diesel totally devoid of natural anti-wear protections, anti-wear power sufficient to ensure trouble-free operation of the components in service injection.

EXAMPLE 4

We present in this example an HFRR test carried out according to the procedure previously described using product D (mixture of monoesters of 1,3-propanediol and oleic sunflower oil monoglyceride) diluted in diesel at levels of 50, 125, 250 and 500 ppm by mass.

The test is also carried out with pure diesel fuel without additives.

The wear values are listed in table 6 below. Fuel composition diameter of the worn cap
expressed in µm Diesel additives free 580 Diesel 50 ppm of product D 580 Diesel 125 ppm of product D 285 Diesel 250 ppm of product D 260 Diesel 500 ppm of product D 215

The above values reflect the average of the results obtained over several test trials.

As before, the performance review shows that a concentration of 125 to 250 parts per million is enough to give a completely diesel lacking natural anti-wear protections, sufficient anti-wear power to ensure in service, trouble-free operation of the injection devices.

Claims (13)

Additive composition usable in middle petroleum distillates characterized by what it comprises at least one partial ester formed between at least one polyol and at minus an aliphatic monocarboxylic acid of 4 to 24 carbon atoms. Additive composition according to Claim 1, characterized in that the said polyol is selected from the group consisting of 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentylglycol, glycerol, diglycerol, polyglycerols, trimethylolpropane and pentaerythritol. Additive composition according to either of Claims 1 and 2, characterized in that said monocarboxylic acid is a saturated linear or branched aliphatic acid, monounsaturated or polyunsaturated, optionally hydroxylated, or isomerized. Additive composition according to one of Claims 1 to 3, characterized in that said monocarboxylic acid is chosen from butyric and caproic acids, caprylic, capric, lauric, myristic, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, ricinoleic, arachidic, gadoleic, behenic, erucic and lignoceric, as well as mixtures of isostearic acid isomers. Additive composition according to one of Claims 1 to 4, characterized in that it comprises at least one partial glycerol ester, i.e. at least one mono or one diglyceride. Additive composition according to claim 5, characterized in that said mono and / or diglyceride is obtained by esterification of glycerol with at least one fatty acid from 8 to 24 carbon atoms. Additive composition according to claim 5, characterized in that said mono and / or diglyceride is obtained by partial glycerolysis of at least one triglyceride. Additive composition according to one of Claims 5 to 7, characterized in that said partial glycerol ester essentially consists of at least one monoglyceride-1 and / or a monoglyceride-2. Additive composition according to one of Claims 1 to 4, characterized in that it comprises at least one partial ester of glycerol and at least one partial ester of at least a second polyol. Additive composition according to claim 9, characterized in that said mixture of partial esters is obtained by partial transesterification of at least one triglyceride using said second polyol, or a mixture of said second polyol with glycerin. Composition of middle petroleum distillate characterized in that it comprises a major proportion of at least one middle petroleum distillate and a proportion minor sufficient to improve the lubricating properties of at least one additive composition according to one of claims 1 to 10. Composition according to Claim 11, characterized in that it comprises the said additive composition at a content of 20 to 2000 ppm. Composition according to Claim 11, characterized in that it comprises the said additive composition at a content of 75 to 200 ppm.