FR2752850A1 - COMPOSITIONS OF ADDITIVES IMPROVING THE LUBRICATING POWER OF FUELS AND FUELS CONTAINING THEM - Google Patents

Abstract

Additive compositions are described which, when added to various refined petroleum fractions, such as petroleum middle distillates, improve their lubricity. These compositions comprise at least one partial ester formed between at least one polyol and at least one aliphatic monocarboxylic acid of 4 to 24 carbon atoms, said partial ester usually consisting of at least one mono or one diglyceride. The compositions of petroleum middle distillates containing these additives are also described, for example at a content of 20 to 2000 ppm and preferably of 75 to 200 ppm by mass.

Description

The present invention relates to additive compositions which, added to

  various refined oil cuts, improve its lubricity.

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

about 130 ° C and about 400 ° C.

  The term "middle distillates" thus designates, in addition to direct distillation cuts, possible mixtures of such cuts with cuts resulting from

  thermal, catalytic or steam cracking, including hydrogenation cracking.

  In jet fuels, the severity of the refining required to obtain improved product characteristics (reduced aromatics and olefins, very low metal contents, very low cloud point and absence of active sulfur) results in significant mechanical components in contact with the

  fuel, including pumps supplying the reactor with fuel.

  In gas turbines and diesel engines, the progressive tightening of legislation aimed at combating the increase in atmospheric pollution has for several years already led to the introduction of a greater proportion of conversion fuels, in particular of processes using hydrogen as a conversion agent. As a result, the natural anti-wear protections traditionally contained in the direct distillation fuels are reduced or even completely eliminated in the case of Nordic diesel fuels meeting the

  Swedish specification "City Fuel Class 1".

  The compositions proposed in the context of the present invention are intended to combat the inadequacy of the anti-wear protection of fuels which have just been described above. These compositions make it possible, in particular, to confer on gas oils, which originally have no natural anti-wear properties, an anti-wear power sufficient to ensure, in use, a satisfactory operation.

  without incident on the injection organs.

  The invention therefore proposes an additive composition that can be used to increase the lubricity of middle petroleum distillates, characterized in that it comprises

  at least one partial ester formed between at least one polyol and at least one monohydric acid

  carboxylic acid of 4 to 24 carbon atoms, said carboxylic acid being linear or branched, saturated, monounsaturated or polyunsaturated, optionally hydroxylated

  or isomerized (as is the case for isostearic acids).

  The polyols considered in the definition of the partial esters used as

  additives in the context of the invention are mainly propanediol1,2 (or mono-

  propylene glycol), 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl-

  glycol, glycerol (or glycerol), diglycerol, polyglycerols, trimethylol-

propane and pentaerythritol.

  The main monocarboxylic acids considered are linear or weakly branched aliphatic acids, generally referred to as "fatty acids", which may be chosen for example from butyric, caprolic or caprylic acids,

  capric, lauric, myristic, palmitic, palmitoleic, stearic, oleic, linoleic

  leic, linolenic, ricinoleic, arachidic, gadoleic, behenic, erucic and

  lignoceric, as well as mixtures of isomers of isostearic acid.

  In the compositions of the invention, the partial esters formed between the glycerol and the fatty acids defined above and, among others,

  these, 1,2-diglycerides and / or 1,3, alone or in mixtures with mono-

  glycerides-1 and / or 2, as well as, and preferentially, monoglycerides-1 and / or 2

  containing only traces of diglycerides-1, 2 and / or 1.3.

  The general formula of mono and diglycerides can be represented as follows monoglyceride-1 monoglyceride-2

H H

H-C-OH H-C-OH

H-C-OH H-C-O - (O) C-R

H - C - O - (O) C - R H - C - OH

I I

H H

1,2-diglyceride-1,3-diglyceride

- H H

H-C-OH H-C-O- (O) C-R

H - C - O - (O) C - R H - C - OH

H-C- O- (O) C -RH-C- O- (O) C -R

I g

H H

  o -R = [- (CH2) n - A - (CH2) m- CH3] When A = -CH2 -, we can have n = 1, with m = 0, 2, 4, 6, 8, 10, 12, 14

16, 18 or 20.

  When A = -C = C -, we can have n = 7, with m = 3,5,7,9; or n = 11, with

m = 7.

H H HH H

  When A = -C = C-C - & = C-, we can have n = 7, with m = 4.

H

H H H H H H H H

  When A = -C = C-C-C = C-C-C = C-, we can have n = 7 and m = 1.

H H

H H HH

i i i i

  When A = - C = C - C -C-, we can have n = 7, with m = 5.

  It is found in the prior art that various methods of

  monoglycerides and mixtures of mono and diglycerides.

  Monoglycerides can be obtained in a very selective way enzymatically; in this case, the formation of monoglyceride-1 or of monoglyceride-2 may be favored, as described, for example, in M. Leclerc's communication: "Novo Nordisk Bioindustrie S.A.", at the Chevreul Days in Toulouse-1990. The enzymatic formation of monoglycerides, in this case monoglyceride-1, is also described by B.Steffen et al. in: "Fat Sci. Technology" 97th year n 4

(1995) pp 132-136.

  Monoglycerides can still be obtained from glycidol and fatty acids, for example according to the European patent EP-B-0 545 477, or, in a way

  more general, using thermal or basic catalysis.

  The synthesis of monoglycerides in admixture with diglycerides is described, for example, in US Pat. No. 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 of 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. We end up with a mixture of

  mono and diglycerides, whose monoglyceride content can reach about 60%.

  In order to obtain monoglycerides with 90 - 94% purity, the molecular distillation of the mixture obtained previously can be carried out, for example according to

  method described by W.Fischer in: "Fette Seifen Anstrichmittel" 83. Jahrgang -

Sonderheft (1981).

  The main impurities encountered in such a method of preparing monoglycerides are traces of free glycerine, diglycerides, triglycerides

and free fatty acids.

  In the context of the present invention, the

  partial esters of glycerol (glycerin), i.e., monoglycerides, diglycerides,

  and mixtures of mono and diglycerides, but also partial esters of other polyols, or partial esters of glycerol and at least one

other polyol in mixtures.

  The monoglycerides and diglycerides considered in the additive compositions of the invention may be derived from the partial esterification of glycerol by free fatty acids (saturated fatty acids, monounsaturated or polyunsaturated, preferably containing from 8 to 24 carbon atoms and resulting for example from the hydrolysis of natural, vegetable or animal oils), used pure or in mixtures; they may also be derived from the transesterification of esters of C1 to C4 alcohols of these same fatty acids with glycerol (glycerolysis); they can finally result

  directly from the transesterification by glycerol of the natural oils themselves.

  same, containing these glycerol-linked fatty acids in the form of triglycerides.

  Although, for the preparation of monoglycerides (or diglycerides), the use of oil or the corresponding mixture of fatty acids gives the same quality of product if it involves the same stoichiometry of glycerin with the number total of fatty acids, the preferred method of preparation consists of the natural oils themselves, which is transesterified by reaction with additional glycerin. For the partial esters of other polyols, it will be preferable to start from a fatty acid or a mixture of fatty acids, unless it is desired to form mixtures of partial esters of glycerol and at least one another polyol, in which case the preferred mode of production will still be the transesterification of a natural oil, by means of this polyol

  alone or a mixture in appropriate proportions of this polyol with glycerine.

  The natural oils and fats which can be used as a basis for synthesis in the methods of preparation of the partial esters by transesterification are very varied. Examples include copra, babassu, palm kernel, tucum, murumuru and palm oils, lard, tallow, melted butter, shea, olive, peanut, kapok oils. , bitter dates, papaya, colocynth, croton, nutmeg, plum, hemp, beech, hibiscus, pulghera, camelina, safflower, niger, sunflower, oleic sunflower, rubber, coconut, purga, walnut, maize, soya, cotton, sorghum, grape seed, flax, tobacco, common pine, afzellia, 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 the preparation of the partial esters of polyols according to the invention are conventional conditions. The excess polyol (s) is used relative to the stoichiometry of the partial esters which it is desired to prepare. Thus, to prepare mono- or diglycerides, it is possible to use from 3 to 9 moles of glycerol per mole of free fatty acid or per mole of fatty acid contained in the starting triglyceride and the operation is carried out.

  for example at temperatures of 180 to 250 C.

  As already indicated above, the petroleum fractions to which the compositions of the invention can be added are generally petroleum middle distillates, such as for example those which serve as a basis for diesel fuels (diesel fuels) or for fuels for terrestrial turbines , marine or aviation. 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 rate of incorporation of the partial esters of polyols to be introduced into the

  The average distillates according to the invention are generally between 50 and 2000 and preferably

between 75 and 200 ppm.

  The following examples illustrate the invention.

EXAMPLES

  First of all, the preparation of the partial esters which will be used is described.

  as additive compositions for middle distillates.

  In these examples, the monoglycerides and diglycerides were synthesized in the laboratory according to known protocols using soda as a 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 glycerine and 1,3-propanediol

(Product D).

  The distribution of fatty acids in the composition of rapeseed and oleic sunflower oils used in the synthesis of monoglycerides and

  diglycerides is recorded in Table 1.

Table 1

  Fatty acid content in% by weight Fatty acids Rapeseed oil Oleic-palmitic sunflower oil 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 - arachidic C20: 0 0.55 0.30 - gadoleic C20: 1 1.10 0, C22: 0.50 - lignoceric C24: 0 0.30 PREPARATIONS A and B The degree of purity of these products was determined by gas chromatography after 'sample. For monoglycerides of rapeseed and oleic sunflower (products A and B), an average purity of

  glycerides (1 + 2) of between 92.5 and 93% by weight. There remains about 6% diglyme-

  cerides (1,2 + 1,3) and of the order of 1% of free fatty acids.

PREPARATION C

  The diglyceride derived from rapeseed oil (product C) contains about 62% diglycerides (1,2 + 1,3), 37% monoglycerides (1 + 2) and about 1% by weight.

Fatty acids.

PREPARATION D

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

  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 of polyol.

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

obtained as described above.

  The anti-wear properties of the compounds A, B, C and D of the invention have been

  the device known as HFRR (High Frequency Reciproca-

ting Rig).

  The test procedure for this tribometer is defined by the CEC (Coordinating European Council) under the reference CEC F-06-T-94. It is currently being standardized by the European Commission.

  the ISO (International Standard Organization) under the reference ISO / DIS 12156.

  In this procedure, the anti-wear power of the gas oils is estimated through the measurement of the wear of a ball of 6 mm diameter in 100Cr6 hardened steel, rubbing

  in reciprocating motion on a polished 100Cr6 steel plane. All of the two

  test vests is bathed by diesel fuel to test.

  A heating system keeps the parts at 60 C, this temperature being very representative of the actual operating conditions of a diesel fuel injection pump on a vehicle. A mass of 200 g squeezes the ball against the plane during the movement. This is done at the frequency of 100 Hz, with a range of motion

of 1 mm.

  During the alternating movement generated by the tribometer, a cap of the ball is worn. The diameter measured by optical microscope of this cap, expressed in micrometers, is even larger than the anti-wear performance of the test product is low. 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 IFRR tests shows the composition

shown in Table 2 below.

Table 2

  Measured properties Methods Values starting point of distillation NF M 07-002 213 C point at 50% NF M 07-002 270 C end point of distillation NF M 07-002 312 C Density at 20 C NF T 60-172 803 kg / m3 kinematic viscosity at 20 C NF T 60-100 4.31 mm2 / 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] l

The example

  In this example, a HFRR test is carried out according to the procedure described above using product A (rapeseed oil monoglyceride) diluted in gas oil at contents of 50, 125, 250 and 500 ppm by weight.

  The test is also performed with pure diesel without additives.

  The wear values are shown in Table 3 below.

Table 3

  Fuel composition diameter of spent cap expressed as lim Gas oil without additive 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 values obtained are the average results from several determinations. The examination of the performances shows that a concentration of approximately 125 parts per million is sufficient to give a diesel fuel completely deprived of natural anti-wear protection, an anti-wear power sufficient to ensure in service, a functioning

  without incident of the injection organs.

EXAMPLE 2

  In this example, a HFRR test is carried out according to the procedure described above using the product B (sunflower oil monoglyceride "I oleic") diluted in gas oil at contents of 50, 125, 250 and 500 ppm (parts

per million by mass).

  The test is also performed with pure diesel without additives.

  The wear values are shown in Table 4 below.

Table 4

  Fuel composition used cap diameter expressed in Sim Diesel without additive 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 values obtained are the average results from several

determinations.

  As previously, the examination of the performances shows that a concentration of approximately 125 parts per million is sufficient to confer on a diesel fuel completely deprived of natural anti-wear protection, an anti-wear power sufficient to

  ensure in service, trouble-free operation of injection devices.

EXAMPLE 3

  In this example, a HFRR test is carried out according to the procedure described above using the product C (rapeseed oil diglyceride) in

  dilution in diesel at levels of 125 and 250 ppm by mass.

  The test is also performed with pure diesel without additives

  The wear values are shown in Table 5 below.

Table 5

  Fuel composition diameter of spent cap expressed in grm Diesel without additive 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 months.

test tests.

  As previously, the examination of the performances shows that a concentration of the order of 125 parts per million is enough to confer on a diesel fuel completely deprived of natural anti-wear protection, an anti-wear power sufficient to ensure in service, an operation without incidents of the organs

injection.

EXAMPLE 4

  In this example, a HFRR test carried out according to the procedure described above is used, using the product D (mixture of monoesters of propanediol-1,3 and of monoglyceride of oleic sunflower oil) diluted in

  diesel fuel at contents of 50, 125, 250 and 500 ppm by weight.

  The test is also performed with pure diesel without additives

  The wear values are shown in Table 6 below.

Table 6

  Fuel composition used cap diameter expressed in liters Diesel without additive 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 tests.

  As previously, the examination of the performances shows that a concentration of 125 to 250 parts per million is sufficient to confer on a diesel fuel completely deprived of natural anti-wear protection, an anti-wear power sufficient to

  ensure in service, trouble-free operation of injection devices.

Claims (10)

  An additive composition that can be used in petroleum middle distillates, characterized in that it comprises at least one partial ester formed between at least one polyol and at least one   s minus an aliphatic monocarboxylic acid of 4 to 24 carbon atoms.   2- additive composition according to claim 1, characterized in that said polyol is selected from the group consisting of 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, butanediol-1,4 , neopentyl glycol, glycerol, diglycerol,   polyglycerols, trimethylolpropane and pentaerythritol.   3. Additive composition according to one 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.   4- additive composition according to one of claims 1 to 3, characterized in that   said monocarboxylic acid is selected from butyric, caproic, caprylic, capric, lauric, myristic, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, ricinoleic, arachidic, gadoleic, behenic,   erucic and lignoceric, as well as mixtures of isomers of isostearic acid.   - Additive composition according to one of claims 1 to 4, characterized in that   comprises at least one partial ester of glycerol, that is to say at least one mono or one diglyceride. 6. 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.   7- additive composition according to claim 5, characterized in that said mono   and / or diglyceride is obtained by partial glycerolysis of at least one triglyceride.   8- Additive composition according to one of Claims 5 to 7, characterized in that   said partial ester of glycerol consists essentially of at least one monoglyceride-1 and / or monoglyceride-2.   9- Additive composition according to one of claims 1 to 4, characterized in that   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 by means of said second polyol, or a mixture of said second polyol with glycerine.   11- middle petroleum distillate composition characterized in that it comprises a major proportion of at least one middle petroleum distillate and a minor proportion sufficient to improve the lubricating properties of at least one   additive composition according to one of claims 1 to 10.   12- Composition according to claim 11, characterized in that it comprises said   additive composition at a level of from 20 to 2000 ppm.   13- Composition according to claim 11, characterized in that it comprises said   additive composition at a level of 75 to 200 ppm.