NL8720496A - Alkyl derivs. of difunctional sulphonic cpds. - used as crystal modifiers in distillate fuels - Google Patents

Abstract

Long chain alkyl derivs. of difunctional sulphonic gp.-contg. cpds. of formula (I) are new, where -Y-R2=SO3(-) (+)D-R2, -SO2NR3R2 or -SO3R2; -X-R1=-Y-R2, -CONR3R1, -CO2(-)(+)D-R1, -R4COOR'-R4COOR1 -NR3COR1, -R4OR1, -R4OCOR1, -R4R1 or -N(COR3)R1; D=NR3.3, HNR3.2, H2NR3 or H3N; R1, R2=alkyl, alkoxyalkyl or polyalkoxyalkyl contg. at least 10C atoms in the main chain; R3=hydrocabryl (same or different); R4=nothing or 1-5C alkylene. In the group (i) the C-C bond is either (a) ethylenically unsatd., when A and B are alkyl, alkenyl or substd. hydrocarbyl groups, or (b) part of a cyclic structure which may be aromatic, polynuclear aromatic or cycloaliphatic.

Description

8720496 * VO 1136

Improved fuel additives.

Mineral oils containing paraffin wax, such as the distillate fuels used as diesel fuel and heating oil, have the property of becoming less liquid as the temperature of the oil decreases. This loss of fluidity is due to the crystallization of the wax into plate-like crystals, which eventually form a sponge-like mass, into which the oil is entrapped, which temperature at which the wax crystals begin to form is known as the "cloud point", and the temperature at which the wax prevents pouring of the oil is known as the "pour point". It has long been known that various additives, when mixed with wax-containing mineral oils, act as pour point elongation agents. These compositions modify the size and shape of wax crystals and reduce the cohesive forces between the crystals and between the wax and the oil in such a way that the oil remains liquid at lower temperature and is therefore pourable and able to pass through coarse filters.

Various pour point depressants have been described in the literature and some of them are in commercial use. For example, U.S. Patent 3,048,479 teaches the use of copolymers of ethylene and C 1 -C 3. vinyl esters, for example vinyl acetate, as pour point depressants for fuels, in particular heating oils and diesel and jet fuels. Hydrocarbon polymeric pour point depressants based on ethylene and higher olefins-1, for example propylene, are also known. US Patent 3,252,771 relates to the use of polymers of olefins_1 with aluminum trichloride / alkyl halide catalysts as pour point depressants in distillate fuels of the "wide boiling" easy-to-treat types, initially of the 1960s were available in the United States. In the later 1960s and early 1970s, greater emphasis was placed on improving the filterability of oils at temperatures between the cloud point and the pour point, as determined by the more stringent Cold Filter Plugging Point (CFPP) Test (IP 309/80) , and since then, '8720411 4 2, many patents have been granted for additives to improve fuel performance in this test. U.S. Patent 3,961,916 teaches the use of a mixture of copolymers to control the size of the wax crystals. UK patent 1,263,152 states that the size of the 5 wax crystals can be controlled by using a copolymer with a lower degree of side chain branching.

Also, for example, UK Patent 1,469,016 proposed that the copolymers of di-n-alkyl fumarates and vinyl acetate, which were previously used as pour point depressants for lubricating oils, be used as auxiliary additives with ethylene / vinyl acetate copolymers treatment of high final boiling point distillate fuels to improve their low temperature flow properties. r

It has also been proposed to use additives based on olefin / maleic anhydride copolymers. For example, according to U.S. Patent 2,542,542, copolymers of olefins, such as octadecene, with maleic anhydride, esterified with an alcohol such as lauryl alcohol, are used as pour point depressants. According to UK Patent 1,468,588, copolymers of 2-28 olefins with maleic anhydride esterified with behenyl alcohol are used as auxiliary additives for distillate fuels. Similarly, according to Japanese Patent Publication 5,654,037 olefin / maleic anhydride copolymers reacted with amines are used as pour point depressants. According to Japanese Patent Publication 5,654,038, the derivatives of the olefin / maleic anhydride copolymers are used in conjunction with conventional middle distillate flow improvers, such as ethylene / vinyl acetate copolymers. Japanese Patent Publication 5,540,640 describes the use of olefin / maleic anhydride copolymers (unesterified) and states that the olefins must have more than 20 carbon atoms to obtain CFPP activity. According to UK Patent 2,192,012, blends of certain esterified olefin / maleic anhydride copolymers and low molecular weight polyethylene are used, which esterified copolymers have no effect when used as the sole additives.

The improvement in CFPP activity by incorporating the additives of the aforementioned patents is achieved by modifying the size and shape of the wax crystals that form to mostly needle-like crystals, generally with particle sizes of 10 microns or larger , typically 30-100 microns. During diesel engine operation at low temperatures, these crystals are not passed through the paper fuel filters of the vehicle, but instead form a permeable cake, which allows the liquid fuel to pass, the wax crystals then dissolving as the engine and fuel heats up, which is possible because of the fuel mass, which is heated by recycled fuel. However, an accumulation of wax can block the filters, leading to starting problems for the diesel vehicle and problems when starting driving in cold weather or failure of heating systems.

With the aid of a computer, the geometry of the n-alkane wax crystal lattice can be calculated in a simple and suitable manner, as well as the energetically preferred geometry of a possible additive molecule. The results become particularly apparent - when they are then graphically displayed using a plotter or a chart terminal. This method is known as "molecular modeling".

Computer programs suitable for this purpose are commercially available and a particularly useful range of programs is distributed by Chemical Design Ltd., Oxford, England (Technical Director: EK Davies) under the designation "Chem-X" .

The growth of paraffin crystals occurs by associating single paraffin molecules with their long sides against the edge of an existing paraffin wafer, as shown schematically in Fig. 1. The association with the top or bottom of the wafer is energetically unfavorable, because in in this case, only one end of the paraffin molecular chain can interact with the existing crystal. The association mainly takes place in the crystallographic (001) plane (see fig. 2). The (001) plane contains the largest number of strongest intermolecular. bonds and thereby prevents the crystal from forming large flat rhombohedral plates (Fig. 3).

The next most stable crystal plane is the (11x) plane, for example 35 (110). The intermolecular association is strongest where the n-alkane molecules are closest together, so that the (110) disk is stronger than the (100) disk.

, 87204l & 4

The crystal grows by extending the (001) plane.

It is important to note that the edges of this plane advance the fastest, which is less the case with the (11x), for example the (110) and (100). Therefore, growth is most controlled by the progression of the (llx) plane.

Since the "head to head" bonds are relatively weak, we generally consider only one molecular (001) plane, assuming the (110), (111) etc. planes are equivalent for our purposes, since the lattice jumps and relative orientations of adjacent, adjacent molecules are the same (Fig. 4).

Fig. 3 is a photography of a wax crystal slide and shows that the macroscopic appearance of the slides is dominated by the (001) plane. It is these plates that can block filters in fuel lines, for example, in vehicles.

According to the invention, this problem is solved by inhibiting or at least greatly reducing the crystal growth in the (001) plane and the (110) and (111) directions.

This is accomplished by the addition of certain additives, whereby wax-containing fuels are obtained with wax crystals of sufficiently small dimensions at low temperatures to pass through filters typically used in diesel engines and heating oil systems.

The invention relates to the use as an additive for paraffin wax-containing distilate fuel of a compound containing at least two substituent groups of such a distance and configuration that they can occupy the positions of wax molecules in the (001) plane cutting with the (110) and / or (111) faces in crystals of the wax, which substituent groups are alkyl, alkoxyalkyl-30 or polyalkoxyalkyl groups having at least ten atoms in the main chain.

The occupation of the faces of the crystal can be explained with reference to Fig. 4, which shows an enlarged plan view of the crystal lattice of a paraffin plate. The viewing direction 35 corresponds to the long axis of the paraffin chains. From each paraffin molecule, only two carbon atoms and four hydrogen atoms (which are shown only once 872 0498 5) can be seen because the other atoms are below the atoms shown, since all the carbon atoms of a molecule are in a molecular plane of symmetry . It can be seen from Fig. 4 that the distances between two molecules in the (100) plane and the (110) plane are practically the same.

These distances are indicated in Fig. 4 as "b" and "d", where b = 4.9 A and d = 4.5 A. The main difference between the (100) and the (110) (or more precisely (11x) where x is 0 or an integer planes is the relative orientation of adjacent paraffin molecules.

Within the (100) plane, the molecular symmetry planes of single molecules are parallel to each other, i.e. the angle is 0 °. In the crystallographic (110) plane, the angle between the molecular planes of symmetry of adjacent molecules is approximately 82 °.

According to the invention, the additives must occupy the positions of paraffin molecules, denoted by "C" and "D" in Fig. 4 *.

This is only possible if the distance between the substituents is about 4.5 - 5.0 A in an energetically available conformation and the angle between the local symmetry planes of the two substituents is about 82 °, preferably 75 - 90 °.

A molecule can be modeled by reading its known atomic coordinates into a computer or by building the structure according to the rules of chemical physics using the computer. Subsequently, the structure can be refined by, for example: (a) calculating the fractional charges on each atom 25 from electronegativity differences (force field method) or quantum mechanical techniques (for example CNDO, Q.C.P.E. 141, Indiana University); (b) structure optimization using molecular mechanics (compare "Molecular Mechanics", U. Burkert and N.L.

30 Allinger, ACS, 1982); (c) minimization of the total energy by optimization of the conformation, in particular by rotation around rotating bonds. Care should be taken here, since the environment on the wax crystal surface differs from that in the gas phase or in solution and it is possible that the additive molecule co-crystallizes together with the paraffin in a conformation which is not the most energetically favorable conformation in the gas phase is. It should also be borne in mind that the additive cannot take a conformation hindered by steric or electronic factors.

Using the following criteria, it can be checked whether an additive molecule fits in the (001) plane of the paraffin-5 crystal lattice in the desired positions C and D, since: (1) the distance between the substituents in the molecule should be approximately be equal to the distance between two adjacent paraffin molecules in the (001) plane intersecting the (lxx) plane, ie about 4.5 A. The relative orientation of the substituents must fit the arrangement of the n-alkanes in the (110) direction, ie the angle between the local symmetry planes of the substituents should be approximately 82 °. The distance and angle can be easily measured using the computer programs.

(2) When the additive molecule must fit into the wax crystal lattice structure and "settle" in two vacant lattice places.

Compounds previously proposed as additives are certain derivatives of phthalic acid, maleic acid, succinic acid and vinyl indene olefins. None of said compounds meet the criterion described above (1). This is shown by the following selected examples.

(a) Phthalic acid diamide at best adopts the conformation shown in Fig. 5 in which the distance between the substituents and the angle is too small. The conformation is energetically unfavorable due to steric hindrance. Reminimalization leads to the deformed conformation shown in Fig. 6.

(b) The situation is analogous to maleic acid diamide, as can be seen in Fig. 7. Due to steric hindrance, reminimalization leads to the distorted conformation of Fig. 8.

(C) Due to steric hindrance, succinic acid cannot assume a conformation approaching the special arrangement of the invention (compare Fig. 9). Rotation around a single C-C bond converts the succinic acid to the conformation shown in Figure 10.

The improvement in CFPP activity by incorporation of the earlier additives according to said patents is achieved. 872 0496 7 by modifying the size and shape of the wax crystals to form, yielding most needle-like crystals, generally having a particle size of 10,000 nanometers or larger, typically 30,000-100,000 nanometers. During the operation of diesel engines 5 at low temperatures, these crystals are not passed through the paper fuel filters of the vehicle, but form a permeable cake on the filter, which allows the liquid fuel to pass, after which the wax crystals will dissolve as the engine and the fuel heating, which can be done by heating the fuel mass 10 by recycled fuel. However, accumulation of wax can block the filters, leading to starting problems for the diesel vehicle and problems when starting in cold weather, as well as failure of fuel heating systems.

The following test methods are used in this application.

The wax appearance temperature (WAT) of the fuel is measured by differential scanning calorimetry (DSC). In this test, a small fuel sample (25 microliters) is cooled at a rate of 2 ° C / minute along with a reference sample of analog thermal capacity, which, however, does not precipitate wax (such as kerosene) in the temperature temperature involved. An exothermic effect is observed when crystallization in the sample begins.

For example, the WAT of the fuel can be measured by the extrapolation technique on the Mettler TA 2000b.

The wax content of the fuel is derived from the DSC graph by integrating the surface between the baseline and the exotherm to the specified temperature. Calibration must have been previously performed with a known amount of crystallizing wax.

The average particle size of the wax crystals is measured by analyzing a Scanning Electron Micrograph of a fuel sample at a magnification of 4000-8000x and measuring the size dimension of at least 40 out of 88 points on a preselected grid. It was found that the wax begins to pass through the paper filters typically used in diesel engines along with the fuel if the average crystal size is less than 4000 nanometers, although the crystal size is preferably less than 3000 nanometers, with more 6.17 2 0 41 i 8 less than 2500 nanometers, in particular less than 2000 nanometers, and most preferably less than 1000 nanometers, realizing the true advantages of passage of the crystals through the paper fuel filter. The actual achievable size depends on the original nature of the fuel and the nature and amount of the additive used, but it has been found that these sizes are smaller and achievable.

The use of the additives according to the invention makes it possible to obtain such small wax crystals in the fuel 10, which results in a considerable advantage for the usability of the diesel engine. This can be shown by pumping stirred fuel through a diesel filter paper, such as used in a Volkswagen Golf or Cummins diesel engine, in the amount of 8-15 milliliters / second and 1.0 - 2.4 1 per minute per quadrant. m filter surface at a temperature which is at least 5 ° C below the WAT, while at least 0.5% by weight of the fuel is in the form of solid wax. Both fuel and wax are considered to have successfully passed the filter if one or more of the following criteria are met.

20 (i) When 18 - 20 l of fuel has passed through the filter, the pressure drop across the filter is not greater than 50 kPa, preferably not greater than 25 kPa, in particular no greater than 10 kPa, and most preferably no greater than 5 kPa.

(ii) At least 60 wt%, preferably at least 80 wt%, especially at least 90 wt% of the wax contained in the original fuel, as determined by the DSC test described previously, is found in the fuel, which leaves the filter.

(iii) While 18-20 L of fuel is being pumped through the filter, the flow rate always remains above 60% and preferably above 80% of the original flow rate.

The portion of the crystals passing through the filter of the vehicle, and the utility advantage resulting from small crystals are highly dependent on crystal length, although the crystal shape is also significant. It has been found that cubic crystals pass through filters somewhat more easily than flat crystals and, when they do not pass, offer less resistance to the fuel flow. Nevertheless, the preferred crystal shape is a flat shape, which basically allows more wax to be deposited as the temperature drops and more wax to precipitate before the critical crystal length is reached than would be the case with a cube of the same length in cubic form .

The fuels obtained by the techniques of the invention have particular advantages over prior distillate fuels, which have been improved in their cold flow properties by the addition of conventional additives. For example, the fuels are useful at temperatures closer to the pour point and are not limited by an inability to pass the CFTP test, as they either pass the CFPT test at significantly lower temperatures or the need to meet those make the test unnecessary. The fuels also exhibit improved cold start performance at low temperatures, which does not rely on hot fuel recirculation to remove unwanted wax deposits. Furthermore, the wax crystals tend to remain in suspension rather than settle and form waxy layers in storage tanks, as is the case with fuels treated with conventional additives.

Distillate fuels within the general class of boiling fuels between 120 and 500 ° C vary considerably in their cooking properties, n-alkane distributions and wash contents. Fuels from Northern Europe generally have lower final boiling points and cloud points than fuels from Southern Europe. The wash contents are generally greater than 1.5% (at 10 ° C below the WAT). Likewise, fuels from other countries around the world vary in the same way with their respective climates, but the wax content also depends on the source of the crude oil. A fuel derived from a Middle East crude oil often has a lower wax content than a fuel derived from any of the wax-containing crudes, such as those from China and Australia.

The extent to which the very small crystals can be obtained depends on the nature of the fuel itself and it may not be possible to produce extremely small crystals in some fuels. If this situation arises, the fuel properties can be modified to allow such small crystals to be obtained, for example, by adjusting the refining conditions and mixing to allow the use of suitable additives.

The wax which precipitates from distillate fuels consists mostly of normal alkanes, which crystallize in an orthorhombic unit cell via a rotator or hexagonal shape, as reported in the literature, for example A. Muller in Proc. Roy. Soc. A. 114, 542 (1927), ibid. J ^ O (1928) 437, ibid. L27 (1930) 417, ibid. JJ8 (1932) 514, 10 A.E. Smith in J. Chem. Phys., 2_1_ (1953) 2229 and P.W. Teare in Acta, Cryst., 12, (1959) 294. As mentioned, two factors are important for the fit of the additive molecule into the wax crystal structure; first, the separation between the n-alkane chains in selected crystal planes, where the important distances are in the (110) 15 and (111) etc. planes or directions and to a lesser extent in the (100) plane.

The chains of the additive must occupy the lattice sites (more than one) in positions on the axes at right angles to the axis of the n-alkane chains in the crystal. These separations are of the order of 4.5-5.5 Å and the closer the chains to the additives are at these distances, the more effective the additive. Second, although less important, the relative orientations of the additive molecular chains preferably match those of the n-alkanes in the crystal. The n-alkyl chains to the additive must be able to closely match the intermolecular distances of the n-25 alkanes in the wax crystal over the (100) and / or (110) and (111) planes where they intersect with the ( 001) flat, and capable of achieving conformations that allow the chains to orient themselves to analog angles such as those of the n-alkanes in the above crystal planes. It has been found that these distances and orientations of the chains on the additive molecule can best be achieved by placing them on adjacent carbon atoms in a cyclic or ethylenically unsaturated compound, provided they are in a cis orientation.

Preferably, the fit is also achieved along the length of the n-alkane chains of the wax, and the total chain length of the additive is preferably of the same order of magnitude as the average chain length in the wax. oil is generally a range of n-alkanes, hence the reference to average dimensions.

The additives therefore generally contain alkyl, preferably n-alkyl chains or chain segments, which can co-crystallize with the wax. It has been found that there should be two or more such chains per molecule and that they should be on the same side of the additive molecule. It is desirable that the additive molecule has two distinct "sides". One side "contains the co-crystallizable alkyl chains and the other" side "contains the smallest number of hydrocarbon groups possible for blocking or preventing further crystallization after the additive molecule has co-crystallized in the n-alkane lattice sites at the Wax Crystals It is also desirable that this "blocking" group be located mid or about halfway through the co-crystallizable n-alkyl chains in the additive.

The preferred additives meet the formula 1 shown on the formula sheet wherein 2. (-) (+) 3 2 (-) (+) 3 2.

-YR is SO NR R, -SO., HNR R) 3 3 2 -SO ^ (_) (+) h nr3r2, -so _. (-) (+) h, nr2, 3 2 1 2 20 -S02NR R or -SO3R; -X-R1 is -Y-R2 or -CONR3R1, -CO2 ^ NR ^ R1, -CO2 (_) ^ HNR ^ R1, -CO2 (_) ^^ NR ^ 1, -CO2 (_) ^ H. jNR1, -r4 -coor, -nr3cor1,4 * 4 i 41 25 R OR, -R OCOR, -RR, -N (COR3) R1 or Z (_) ^ NR ^ R1 ;; -Z (_) is SO3 ^ "^ or -CO2 ^" ^; 1 2 R and R alkyl-? represent alkoxyalkyl or polyalkoxyalkyl groups having at least 10 carbon atoms in the main chain; 3 3 30 R is a hydrocarbon group, where each group R can be the same or different 4, and R is nothing or Cj-Cj. alkylene, and in the molecular portion of formula 2.

The ring atoms in such a cyclic compound are preferably carbon atoms, but may also contain a ring N, S or O 35 atom to form a heterocyclic compound.

Examples of aromatic-based compounds from which the additives can be prepared are compounds of formula 3, in which the aromatic group may be substituted.

They can also be obtained from polycyclic compounds, i.e., those with two or more ring structures, which can have various shapes. They can be (a) fused benzene structures, (b) fused ring structures, in which no ring or not all rings are benzene, (c) linked rings, (d) heterocycles, (e) non-aromatic or partially saturated ring systems or (f) three-dimensional structures.

Condensed benzene structures from which the compounds can be derived are, for example, naphthalene, anthracene, phenanthrene and pyrene.

The condensed ring structures, in which no ring or not all rings are benzene, are, for example, azulene, indene, hydro-indene, fluorene, diphenylene. For example, a compound to which rings are coupled together is diphenyl. Suitable heterocyclic compounds from which they may be derived are, for example, quinoline, pyridine, indole, 2: 3 dihydroindole, benzofuran, coumarin, isocarin, benzothiophene, carbazole and thiodiphenylamine. Examples of non-aromatics or partially saturated ring systems are decal (decahydro-naphthalene), α-pinene, cadinene, bomylene. Suitable three-dimensional compounds are, for example, norbornene, bicycloheptane (norbornane), bicyclooctane and bicyclooctene.

The two substituents X and Y must be bonded to 25 adjacent ring atoms in the ring when there is only one ring, or to adjacent ring atoms in one of the rings when the compound is polycyclic. In the latter case, this means that if one were to use naphthalene, these substituents cannot be attached to the 1,8 or 4,5 positions, but should be attached to the 1,2, 2,3, 3,4, 5,6, 6,7 or 7,8 positions.

These compounds are reacted to form the esters, amines, amides, half esters / half amides, half ethers or salts used as the additives. Preferred additives are the salts of a secondary amine containing a hydrogen and carbon containing group or groups having at least 10 carbon atoms, preferably at least 12 carbon atoms. Such amines or salts can be prepared by reacting the previously described acid or anhydride with an amine or by reacting a secondary amine derivative with carboxylic acids or anhydrides. Water removal and heating are generally necessary to prepare the amides from the acids. The carboxylic acid can also be reacted with an alcohol of at least 10 carbon atoms or a mixture of an alcohol and an amine.

The hydrogen and carbon containing groups in the substituents are preferably hydrocarbon groups, although halogenated hydrocarbon groups may also be used, preferably with only a small amount of halogen atoms (eg chlorine atoms), eg less than 20 wt%. The hydrocarbon groups are preferably aliphatic, for example alkylene. They are preferably linear. Unsaturated hydrocarbon groups, for example alkenyl, can be used, but are not preferred.

The alkyl groups preferably contain at least 10 carbon atoms, preferably 10-22 carbon atoms, eg 14-20 carbon atoms, and are preferably linear or branched at the 1 or 2 positions. If branching is present in more than 20% of the alkyl chains, the branching should be methyl. The other hydrogen and carbon-containing groups can be shorter, for example, contain less than 6 carbon atoms, or optionally contain at least 10 carbon atoms. Examples of suitable alkyl groups are methyl, ethyl, propyl, hexyl, decyl, dodecyl, tetradecyl, eicosyl and docosyl (behenyl). Examples of suitable alkylene groups are hexylene, octylene, dodecylene and hexadecylene, but they are not preferred.

In the preferred embodiment, wherein the intermediate is reacted with the secondary amine, one of the substituents is preferably an amide and the other is an amine or dialkyl ammonium salt of the secondary amine.

Particularly preferred additives are the amides and amine salts of secondary amines.

These additives are generally used in combination with other additives to obtain the fuels according to the invention. Examples of these other additives are those, referred to as "comb" polymers of the general formula 4, wherein D = R, Co.OR, OCO.R, R'CO.OR or OR E = H or CH3 or D or R 7 7 0498 ° * 14 m = 1.0 (homopolymer) to 0.4 (molar ratio) J = H, R ', aryl or heterocyclic group, R'CO.OR K = H, CO.OR' , OCO.R ', OR', CO 2 H L = H, R ', CO.OR', OCO.R ', aryl, CO 2 H 5 n = 0.0-0.6 (molar ratio) R 1 C 10 R'> Cj

Another monomer may be terpolymerized if necessary. When these other additives are copolymers of alkene-10-nen-1 and maleic anhydride, they can be conveniently prepared by polymerizing the monomers without solvent or in solution in a hydrocarbon solvent such as heptane, benzene, cyclohexane or white oil , at a temperature generally in the range of 20-150 ° C, usually promoted by a peroxide or azo-type catalyst, such as benzoyl peroxide or azo-di-isobutyro-nitrile, under a blanket of inert gas, such as nitrogen or carbon dioxide to exclude oxygen. Preferably, but not necessarily, equimolecular amounts of the olefin and maleic anhydride are used, although mole ratios of 2: 1 to 1: 2 are also suitable.

Examples of olefins which can be copolymerized with maleic anhydride are decene-1, dodecene-1, tetradecene-1, hexadecene-1, octadecene-1.

The copolymer of the olefin and maleic anhydride can be esterified by any suitable technique; preferably, but not necessarily, the maleic anhydride is esterified for at least 50%. Examples of alcohols to be used are n-decanol-1, n-dodecanol-1, n-tetradecanol-1, n-hexadecanol-1, n-octadecanol-1. The alcohols may contain at most one methyl branch per chain, for example 1-methylpentadecanol-1,2-methyl-tridecanol-1. The alcohol 30 can be a mixture of normal and mono-methyl branched alcohols.

Any alcohol can be used for the esterification of copolymers of maleic anhydride with one of the alkenes. Preferably pure alcohols are used in place of the commercially available alcohol mixtures, but when mixtures are used R refers to the average number of carbon atoms in the alkyl group, and when alcohols are branched at the 1 or 2 position R has involved

"811 Ö 4 8 I

15 king on the linear spinal segment of the alcohol. When mixtures are used, it is important that no more than 15% of the groups 1 1 R have the value R + 2. The choice of the alcohol will of course depend on the choice of the maleic anhydride copolymerized olefin, such that R + R is between 18 and 38. The preferred value of R + R may depend on the cooking properties of the fuel , in which the additive is to be applied.

The comb polymers can also be fumarate polymers and copolymers, as described in European patent applications 0153176, 10 0153177, 85301047 and 85301048. Other suitable comb polymers are the polymers and copolymers of olefins-1 and the esterified copolymers of styrene and maleic anhydride.

Examples of other additives that can be used in conjunction with the cyclic compound are the polyoxyalkylene esters, ethers, ester / ethers and mixtures thereof, especially containing at least one, preferably at least two C 1 -C 2 -C linear linear saturated alkyl groups and a polyoxyalkylene glycol group with a molecular weight of 100-5000, preferably 200-5000, the alkyl group in the polyoxyalkylene glycol containing 1-4 carbon atoms. These materials are the subject of European Patent No. 0,061,895 B. Other such additives are described in U.S. Patent No. 4,491,455.

The preferred esters, ethers or ester / ethers suitable for the invention can be structurally depicted by the formula: R - 0 (A) - O - R "wherein R and R" are the same or different and n-alkyl or a group of formula 5, 6 or 7, which alkyl group is linear and saturated and contains 10-30 carbon atoms, and A represents the polyoxyalkylene segment of the glycol, wherein the alkylene group contains 1-4 carbon-30 atoms, such as polyoxymethylene polyoxyethylene, or polyoxytrimethylene molecular moiety, which is substantially linear; some degree of branching with lower alkyl chains (such as in polyoxypropylene glycol) is permissible, but preferably the glycol is substantially linear. A can also contain nitrogen.

Suitable glycols in general are the substantially linear polyethylene glycols (PEG) and polypropylene glycols (PPG) having a .1120416 16 molecular weight of 100-5000, preferably about 200-2000. Esters are preferred and fatty acids having 10-30 carbon atoms suitable for reaction with the glycols to form the ester additives, it being preferred that C18-C24 fatty acid, especially behenic acids, be used. The esters can also be prepared by esterification of polyethoxylated fatty acids or polyethoxylated alcohols.

Polyoxyalkylene diesters, dieters, ether / esters, and mixtures thereof are suitable as additives, with diesters being preferred for use in narrow boiling distillates, which may also include below-appropriate amounts of monoethers and monoesters, and are often formed in the manufacturing process . It is important for the performance of the additive that a major amount of the dialkyl compound is present. Stearic acid or management acid diesters of polyethylene glycol, polypropylene glycol or mixtures of polyethylene glycol and polypropylene glycol are particularly preferred.

The additives to be used may also contain flow-enhancing copolymers of ethylene and unsaturated esters. The unsaturated monomers which can be copolymerized with ethylene include unsaturated mono- and diesters of the general formula 8 wherein Rg represents hydrogen or methyl, Rg is a -QOCRg group in which Rg is hydrogen or a C 1 -C 20 Qf C 1 -C 2 and preferably C 1 -C C is a linear or branched alkyl group, or wherein R 8 is a -COORg group, in which R 8 has the aforementioned meaning but does not represent hydrogen, and R 8 is hydrogen or -COORg as previously defined. The monomer, wherein Rg and Rg represents hydrogen and Rg is -OOCRg, includes vinyl alcohol esters of C-C 0, usually C-C 0 monocarboxylic acid, and preferably 1 2 C 2 -C 29 9 βνοοηϋ3 ^ C1 -C18 monocarboxylic acid, and preferably C1 -C8 monocarboxylic acid. Examples of vinyl esters that can be copolymerized with ethylene are vinyl acetate, vinyl propionate, and vinyl butyrate or isobutyrate, with vinyl acetate being preferred. When used, these copolymers preferably contain 5-40% by weight of the vinyl ester, especially 10-35% by weight of vinyl ester. They may also be blends of two copolymers as described in U.S. Patent 3,961,916. Preferably, these copolymers have a number average molecular weight, measured by vapor phase osmometry, of 1000 - 10,000, preferably 1000 - 5000.

.8720496 17

The additives to be used may also contain other polar compounds, ionic or nonionic, which can act as wax crystal growth inhibitors in fuel. Polar nitrogen-containing compounds have been found to be particularly effective when used in combination with the glycol esters, ethers or ester / ethers. These polar compounds are generally amine salts and / or amides formed by reacting at least one mole portion of hydrocarbyl-substituted amines with a mole portion of hydrocarbic acid having 1-4 carboxylic acid groups or their anhydrides; ester / amides can also be used, which contain 30-300, preferably 50-150, carbon atoms in total. These nitrogen compounds are described in U.S. Patent 4,211,534. Suitable amines are usually C12 -C40 Fine-secondary, tertiary or quaternary amines or long chain mixtures thereof, but shorter chain amines can also be used, provided that the resulting nitrogen compound is oil soluble and therefore normally normally contains about 30-300 carbon atoms in total. The nitrogen compound preferably contains at least one linear C8 -C24 alkyl segment.

Suitable amines include primary, secondary, tertiary or quaternary amines, but secondary amines are preferred. Teriary and quaternary amines can only form amine salts. Examples of amines are tetradecylamine, cocoamine, hydrogenated tallowamine and the like. Examples of secondary amines are dioctadecyl amine, methyl behenylamine and the like. Mixtures of amines are also suitable, and many amines derived from natural materials are mixtures. The preferred amine is a secondary hydrogenated talloamine of the formula wherein and R 2 are alkyl groups derived from hydrogenated tallo fat composed of about 4% C 31, 31% C 16 and 59% C 14.

Examples of suitable carboxylic acids (and their anhydrides) for the preparation of these nitrogen compounds are cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, naphthalenedicarboxylic acid and the like. Generally, these acids contain about 5-13 carbon atoms in the cyclic molecular moiety. Preferred acids suitable according to the invention are benzene dicarboxylic acids, such as phthalic acid, isophthalic acid and terephthalic acid.

Phthalic acid or its anhydride is particularly preferred. The particular compound of the preferred compound is the amide amine salt formed by reacting 1 mole part phthalic anhydride with 2 mole parts dihydrogenated tallow amine. Another preferred compound is the diamide formed by dehydration of this amide amine salt.

Hydrocarbon polymers can also be used as part of the additive combination for the preparation of the fuels of the invention. They can be represented by the general formula 9, wherein T = H or R '10 U = Η, T or aryl v = 1.0 - 0.0 (molar ratio) w = 0.0 - 1.0 (molar ratio) R is alkyl. *

These polymers can be prepared directly from ethylenically unsaturated monomers or indirectly by, for example, hydrogenation of the polymer prepared from other monomers such as isoprene and butadiene.

A particularly preferred hydrocarbon polymer is a copolymer of ethylene and propylene with an ethylene content of preferably 50-60% (w / w).

The amount of additive required for the preparation of the distillate fuel oil according to the invention will vary depending on the fuel, but is generally 0.001-0.5 wt.%, For example 0.01-0. 1% by weight (active substance), based on the weight of the fuel. The additive may suitably be dissolved in a suitable solvent to form a concentrate of 20-90 wt. %, for example 30-80% by weight in the solvent. Examples of suitable solvents are kerosene, aromatic naphtha1s, mineral lubricating oils, etc.

The invention is illustrated by the following examples, in which the largest of the wax crystals in the fuel were measured by placing fuel samples in bottles of 60 ml, which were placed in coolers at about 8 ° C above the temperature for 1 hour. cloud point of the fuel were maintained while the fuel temperature stabilized. Then the box was cooled to the test temperature at a rate of 35 1 ° C / hour, which was then maintained.

, S 7 2 0 4 11 19

A pre-prepared filter support, consisting of a sintered ring with a diameter of 10 mm, surrounded by a 1 mm wide annular metal ring, carrying a silver membrane filter of 200 nanometer quality, which is held in position by two vertical pins, is placed on a vacuum unit installed. A vacuum of at least 80 kPa is applied, after which the cooled fuel is dripped onto the membrane from a clean dropper pipette, until a small round puddle just covers the membrane. The fuel is dripped slowly to maintain the puddle for several minutes, and after about 10 to 20 fuel drops have been supplied, the puddle is allowed to leak leaving a very thin dull layer of fuel-moistened washcloth on the membrane. A thick layer of wax cannot be washed acceptably and a very thin layer can be washed away. The optimal layer thickness is a function of the crystal particles, where "leaf-like" crystals require thinner layers than "nodular" crystals. It is important that the final cake has a dull appearance. A "shiny" cake indicates an excess of residual fuel and crystal "lubrication" and should be cartilaged.

The cake is then washed with a few drops of methyl ethyl ketone, which is allowed to drain completely. The process is repeated several times. When the washing is complete, the methyl ethyl ketone will disappear very quickly leaving a "radiant matte white" surface, which will turn gray upon addition of another drop of methyl ethyl ketone.

The washed sample is then placed in a cold desiccator and held there until ready for coating in the SEM. It may be necessary to keep the sample refrigerated to maintain the wax, in which case the sample must be stored in a cool box before being transferred (in an appropriate sample transport vessel) to the SEM to allow ice crystal formation on the sample surface to prevent.

During coating, the sample should be kept as cold as possible to minimize damage to the crystals. In electrical contact with the "stage", it is best provided by a locking screw, which presses the annular ring against the side of a well in the "stage", arranged to face the sample surface 8 8 2 0 4 9 6 20 the image plane of the instrument. Electrically conductive paint can also be used.

Once coated, the micrographs are obtained in a conventional manner on the Scanning Electron Microscope (SEM). The photo-5 micrographs are analyzed to determine the mean crystal size by attaching a transparent sheet marked 88 points (as pieces) at the intersections of a regular grid of 8 rows and 11 columns equally spaced, at an appropriate micrography. The magnification should be such that only some of the largest crystals are hit by more than one piece, with 4000-8000 times proven suitable. The crystal can be measured at any grid point if the dot contacts a crystal size, the shape of which can be clearly defined. A measurement of "scattering" in the form of the Gaussian standard deviation of crystal length 15 is also made using Bessel correction.

The wax content before and after the filter is measured with a Differential Scanning Calorimeter DSC (such as the du Pont 9900 series), which can produce a graph with an area of approximately 100 cm2 / 1% fuel in the form of wax with an instrument noise induced 20 output variation with a standard deviation of less than 2% of the mean output signal.

The DSC is calibrated using an additive that produces large crystals, which are certainly removed by the filter, this calibrated fuel being fed to the test temperature at the test temperature and the WHAT of the thus dewaxed fuel to the DSC is measured. Subsequently, the samples of the fuel from the tank and the fuel after the filter are analyzed on the DSC and for each fuel the area above the baseline to the WHAT of the calibration fuel is determined.

The ratio of DSC area for sample after the filter / DSC area for sample from the tank x 100 is the percentage of wax remaining after the filter.

The cloud point of distillate fuels was determined by the standard Cloud Point Test (IP-219 or ASTM-D 2500); Other measurements of the beginning of crystallization are the Wax Appearance

Point (WAP) Test (ASTM D.3117-72) and the Wax Appearance Temperature (WAT),. §72 8488 21 measured by DSC using a Mettler TA 2000B Differential Scanning Calorimeter.

The ability of the fuel to pass through a main filter of a diesel vehicle was determined in a device consisting of a typical main filter of a diesel vehicle mounted in a standard housing in a fuel line; the Bosch type, as used in a 1980 Volkswagen Golf diesel passenger car, and a Cummins FF105, as used in the Cummins NTC engine series, are suitable. A reservoir and a supply system, capable of supplying half of the fuel in a normal fuel tank, connected to a fuel injection pump, as used in the Volkswagen Golf, is used to transfer fuel from the tank at a constant flow rate. suction the filter, as is also the case in the vehicle. Instruments are provided for measuring the pressure drop across the filter, the flow rate from the injection pump and the temperatures in the unit. Barrels for collecting the pumped fuel, both "injected" fuel and the excess fuel, are provided.

In the test, the tank is filled with 19 kg of fuel and 20 tested for leakage. If found satisfactory, the temperature is stabilized at an air temperature of 8 ° C above the cloud point of the fuel. The unit is then cooled to the desired test temperature at a rate of 3 ° C / hour and held there for at least 3 hours for fuel temperature stabilization. The tank is shaken vigorously to completely disperse the wax present; a sample is taken from the tank and 1 l of fuel is removed via a sampling point in the discharge pipe immediately after the tank and returned to the tank. Then the pump is started with the speed of the pump set to the same value as the speed of the pump at a road speed of 110 kg / hour. In the case of the Volkswagen Golf, this is 1900 rpm, corresponding to an engine speed of 3800 rpm. The pressure drop across the filter and the flow rate of the fuel from the injection pump are monitored until the fuel is exhausted, which is typically the case after 30 - 35 minutes.

If the fuel supply to the injectors can be kept at 2 ml / second (excess liquid will be approximately 6.5-7 ml / second.% Tt 04 i i f 22), the result is "successful". A drop in fuel flow to the injectors is considered a "limit case"; a current of zero means "failed".

A "successful" result can typically be accompanied by an increasing pressure drop across the filter, which can be as high as 60 kPa. Generally, significant amounts of wax must pass through the filter to achieve such a result. A "successful" result is characterized by a test in which the pressure drop across the filter does not rise above 10 kPa, and is the first indication that most of the wax has passed through the filter; an excellent result has a pressure drop of less than 5 kPa.

Furthermore, fuel samples are taken from the "excess" fuel and the "injector feed" fuel, ideally every 15 minutes for the entire run. These samples are compared together with the pre-test tank samples by DSC to determine the amount of feed wax that has passed through the filter.

Samples of pre-test fuel are also taken, SEM samples are taken after the test to compare the wax crystal size and type with actual performance.

The following additives were used.

Additive 1

The Ν, dial-dialkylammonium salt of 2-dialkylamido-benzene-sulfonate, in which the alkyl groups are nC ^ g_ ^ Q ^ 33 37, prepared by reacting 1 mole of ortho-sulfobenzoic acid cyclic anhydride with 2 moles of di- (hydrogenated) talloamine in a xylene solvent at a concentration of 50% (w / w). The reaction mixture was stirred at a temperature between 100 ° C and the reflux temperature. The solvent and chemicals should be kept as dry as possible to prevent hydrolysis of the anhydride.

The product was analyzed by 500 MHz NMR spectroscopy, confirming that the structure was of Formula 10.

The molecular model of this compound is shown in Fig. 11. Additive 2 35 A copolymer of ethylene and vinyl acetate with a vinyl acetate content of 17% by weight, a molecular weight of 3500 and a side chain branching degree of 8 methyl groups per 100 methylene groups, as measured by 500 MHz NMR.

Additive 3

A styrene dialkyl maleate copolymer, prepared by esterifying a 1: 1 molar styrene-maleic anhydride copolymer with 2 moles of a 1: 1 molar mixture of C 2 H 25 OH and C 14 H 29 OH per mole of anhydride groups (a small excess of 5% alcohol used) with p-toluenesulfonic acid as a catalyst (1/10 mol) in xylene solvent; the product had a molecular weight (Mn) of 50,000 and contained 3% (w / 10 wt) untreated alcohol.

Additive 4

The dialkyl ammonium salts of 2-N, N-dialkylamidobenzoate formed by mixing 1 mole part phthalic anhydride with 2 mole parts dihydrogenated tallowamine at 60 ° C.

15 The results were as follows.

Example 1

Fuel properties

Cloud point -14 ° C

WHAT -18.6 ° C

20 Initial boiling point 178 ° C

20% 230 ° C

90% 318 ° C

Final boiling point 3 5 5 0 C

Wax content at -25 ° C 1.1 wt% 25 The fuel contained 250 parts per million of each of additives 1, 2 and 3 and the test temperature was -25 ° C. The wax crystal size was found to be 1200 nanometers and more than 90% by weight of the wax passed through the Cummins FF105 filter.

During the test, the pressure drop across the filter 30 increased by only 2.2 kPa, further demonstrating that wax had passed through the filter.

Example 2

Example 1 was repeated, the wax crystal size being found to be 1300 nanometers and the maximum final pressure drop across the filter being 3.4 kPa 0.072. 0411 24

Example 3

Fuel properties

Cloud point 0 ° C

WHAT -2.5 ° C

5 Initial boiling point 182 ° c

20% 220 ° C

90% -354 ° C

Final boiling point 385 ° C

Wax content at test temperature 1.6 wt% ^ Of each of additives 1, 2 and 3, 250 parts per million was used. The wax crystal size was found to be 1500 nanometers and about 75% by weight of the wax passed at the test temperature of -8.5 ° C through the Bosch 145434106 filter. The maximum pressure drop across the filter was 6.5 kPa.

15

Example 4

Example 3 was repeated, the wax crystal size being 2000 nanometers, of which about 50% by weight passed through the filter, yielding a maximum pressure drop of 35.3 kPa.

Example 5 20

The fuel used in Example 3 was treated with 400 ppm of Additive 1 'and 100 ppm of a mixture of Additive 2, after which the fuel was tested as in Example 3 at -8 ° C, at which temperature the wax content was 1.4 wt. %. The wax crystal size was 2500 nanometers and 50% by weight of the wax passed through the filter 25 with a maximum final pressure drop of 67.1 kPa.

When this fuel was used in the test rig, the pressure drop increased relatively quickly and the test failed. This is believed to be caused by the fact that the crystals, as shown in the photo, are flat. Flat crystals, which do not pass through the filter, tend to cover the filter with a thin, impermeable layer. On the other hand, "cube-like" (or "nodular") crystals, when not passed through the filter, collect in a relatively loose "cake", allowing fuel to pass until the mass becomes so large that the filter fills and the total thickness of the wax "cake" is so great that the pressure drop is again excessive.

35., 87 2 04 9 8 25

Example 6 (comparative)

The fuel used in Example 3 was treated with 500 ppm of a mixture of 4 parts of additive 4 and 1 part of additive 2 and then tested at -8 ° C; the wax crystal size was found to be 6300 nanometers and 13% by weight of the wax passed through the filter.

This example is one of the very best examples of the prior art where excellent results are obtained without crystal passage.

Figures 1-6 show Scanning Electron Micrograph of 10 wax crystals that form in the fuel of Examples 1-6.

Examples 1-4 therefore show that the crystals can reliably pass through the filter, that the excellent low temperature behavior can be extended to much higher fuel wash levels than previously possible, and also to temperatures below 15 WHAT of the fuel than was possible so far. This applies irrespective of the particularities of the fuel system, such as the possibility of recirculation of fuel from the engine to heat the fuel pumped from the fuel tank, the ratio of fuel supply to fuel recirculation, the ratio of the surface area of the main filter to the fuel supply flow and the dimensions and location of pre-filters and screen meshes.

These examples show that for the tested filters, crystal lengths of less than about 1800 nanometers result in dramatically better fuel behavior.

25 Example 7

In this example, additive 1 was added to a distillate fuel with the following properties:

Initial boiling point 180®C

20% 223 ° G

90% 336 ° C

Final boiling point 365 ° C

WHAT 5.5 ° C

Cloud point -3.5 ° C

For comparison purposes, the following 35 additives were also added to the distillate fuel: * 872 84 Si 26

Additive A:

A mixture of ethylene / vinyl acetate copolymers. One of these copolymers was additive 2 (1 part by weight) and the other (3 parts by weight) had a vinyl acetate content of 36% by weight, a molecular weight of 5 (Mn) of 2000 and a degree of side chain branching between 2 and 3 methyl groups per 100 methylene groups, as measured by 500 MHz nmr.

Additive B:

A mixture of additives 4 and 2 in a molar ratio of 4: 1.

10 Addition C:

The dibehenate of a polyethylene glycol blend with an average molecular weight of 600.

Additive D:

An ethylene / propylene copolymer having an ethylene content of 56 wt.% And a number average molecular weight of about 60,000.

The additives were added in the amounts listed in the following table, and tests were performed according to the PCT as set forth below:

Programmed Cooling Test (PCT) 20 This is a slow cooling test, intended for correlation with the pumping of a stored heating oil. The cold flow properties of the additive-containing fuel are determined according to the PCT as follows. 300 ml fuel is cooled linearly at the rate of 1 ° C / hour to the test temperature, after which the temperature is kept constant. After a 2 hour stay at the test temperature, about 20 ml of the surface layer is removed by suction to prevent the test from being affected by the abnormally large wax crystals formed at the oil / air interface during cooling. Wax which has settled in the bottle is dispersed by gentle stirring, after which a CFPPT filter assembly is inserted. The tap is opened to apply a vacuum of 500 mm of mercury pressure and closed when 200 ml of fuel has passed through the filter in the graduated collecting vessel: the test is successful if the 200 ml is passed through a filter 35 with a filter within 10 seconds. given mesh size is collected, or has failed if flow rate is too slow, indicating that the filter has become blocked. 8720496 27.

The mesh size of the filter passed at the test temperature shall be recorded.

(1) CFPPT - Cold Filter Plugging Point Test (CFPPT), described in detail in "Journal of the Institute of Petroleum", 52, (No. 510) June 1966, 173-185.

Example 8

The fuel used in this example had the following properties: 10 (ASTM-D86)

Initial boiling point 190 ° C

20% 246 ° C

90% 346 ° C

Final boiling point 3 74 ° C

15 WHAT -1.5 ° C

Cloud point + 2.0 ° C

The fuel was treated with 1000 parts of active ingredient per million of the following additives: (E) a mixture of additive 2 (1 part by weight) and additive 4 (9 parts by weight).

(F) The commercially available ethylene / vinyl acetate copolymer additive sold by Exxon Chemicals as ECA 5920.

(G) A mixture of: 25 1 part additive 1 1 part additive 3

1 part additive D

1 part additive K.

(H) The commercially available ethylene / vinyl acetate copolymer additive, sold by Amoco as 2042E.

(I) The commercially available ethylene / vinyl propionate copolymer additive sold by BASF as Keroflux 5486.

(J) No additive. "(K) The reaction product of 4 moles of dihydrogenated talloamine and 1 mole of pyromellitic anhydride. The reaction is carried out under stirring under nitrogen without solvent at 150 ° C for 6 hours.

. Felt 0411 28

Subsequently, the following behavioral properties of these fuels were measured.

(i) The fuel's ability to pass through the main diesel fuel filter at -9 ° C while measuring the 5 percent passing through the filter, with the following results: f

Additive Time to failure% passed was E 11 min 18 - 30% F 16 min 30% 10 G no failure 90 - 100% H 15 min 25% I 12 min 25% J 9 min 10% (ii) The pressure drop across the main filter by time, the results of which are shown graphically in Fig. 12.

(iii) The settling wax was measured by cooling 100 ml of fuel in a graduated graduated cylinder. The cylinder is operated at a rate of 1 ° C / hour from a temperature of preferably 10 ° C, but not less than 5 ° C

20 cooled above the cloud point of the fuel to the test temperature and then held there for a prescribed time. The test temperature and residence time depend on the application, especially diesel fuel and heating oil.

Preferably, the test temperature is at least 5 ° C below the cloud point and the minimum residence time at the test temperature is at least 4 hours. Preferably, the test temperature is 10 ° C or more below the cloud point of the fuel and the residence period is 24 hours or more.

At the end of the residence period, the graduated cylinder is inspected and the degree of wax crystal settling is visually measured as the height of a wax layer above the bottom of the cylinder (0 ml) and expressed in terms of a percentage of the total volume (100 ml). When a clear fuel is seen above the settled wax crystals, this form of measurement is often sufficient to form an opinion over the wash settling.

Sometimes, however, the fuel above a settled wax crystal is cloudy or it can be seen that the wax crystals are visibly denser as they approach the bottom of the cylinder. In that case, a more quantitative analysis method is applied. The top 5% (5 ml) of fuel is carefully extracted and stored; the next 5 45% is aspirated and cartaged; the subsequent 5% is searched and stored; the subsequent 35% is suctioned and drained; finally, the bottom 10% is collected after heating to dissolve the wax crystals. These saved samples are further referred to as top, middle and bottom samples. It is important that the vacuum applied to remove the samples is relatively low, in particular 200 mm water pressure, and that the tip of the pipette is placed just on the surface of the fuel to prevent flow in the liquid, which could disturb the concentration of wax in different layers within the cylinder. Samples 15 are then heated to 60 ° C for 15 minutes and then tested for wax content by Differential Scanning Calorimetry (DSC).

In this case, a Mettler TA 2000B DSC machine was used. A 25 microliter sample is placed in the sample cell and regular kerosene is introduced into the reference cell; they are cooled at a rate of 22 ° C / min from 60 ° C to at least 10 ° C, but preferably 20 ° C above the WAT, and then cooled at a rate of 2 ° C / min to about 20 ° C below the WHAT. A reference measurement must be made of the unrefined, uncooled treated fuel. The degree of settling is then related to the WHAT (or WHAT = 25 WHAT settled sample - THAT originally). Negative values indicate fuel dewaxing and positive values indicate wax enrichment from settling. The wax content can also be used as a measure of settling from these samples. This is shown by% wax (% wax =% was settled sample -% was original) and again negative values indicate dewaxing of the fuel and positive values indicate wax enrichment by settling.

In this example, the fuel was cooled to -9 ° C at a rate of 1 ° C / hour from + 10 ° C, followed by a 48 hour residence time at this temperature before testing. The results were as follows: 1720431 30

Additive Visually observed WHAT ° C data settled samples wash sedimentation Upper-Lower-Lower _ ~ ___ 5th 5% 5th 5% 10% _ E completely cloudy -10.80 -4.00 -3.15 5 closer to the bottom F 50% clear -13.35 -0.80 -0.40 over G 100% -7.85 -7.40 -7.50 H 35% clear -13.05 -8.50 +0.50 10 over I 65% clear above J 100% semi-gel -6.20 -6.25 -6.40 (The results are also shown graphically in Figure 13).

15 WHAT originally WHAT (° C) (settled samples) (fuelless) Top-Middle-Bottom _ 5% th 5% th 10% E -6.00 -4.80 +2.00 +2.85 F -5.15 -8.20 +4.35 +4.75 20 G -7.75 -0.10 +0.35 +0.25 H -5.00 -8.05 -3.50 +4, 50 J -6.20 0.00 -0.05 -0.20 '(It appears that a significant reduction in WAT can be achieved by the most effective additive (G)), 25% WAT (settled samples)

Top-Middle- Bottom 5% th 5% th 10% E —0.7 +0.8 +0.9 F -0.8 +2.1 +2.2 30 G ± 0.0 +0, 3 +0.1 H -1.3 -0.2 +1.1 J -0.1 ± 0.0 ± 0.1

These results show that when the crystal size is reduced by the presence of additives, the wax crystals settle relatively quickly. For example, untreated fuels, when cooled below their cloud point, exhibit little wax crystal settling, because the plate-like crystals lock together and cannot tumble freely in the liquid, resulting in a gel-like structure; however, when a flow improver is added, the crystals can be modified so that their habit becomes less plate-like and needles are formed with dimensions in the range of tens of micrometers, which needles can move freely in the liquid and settle relatively quickly. This wax crystal settling can cause problems in storage tanks and vehicle systems. Concentrated wax layers can be aspirated unexpectedly, especially when the fuel level is low or when the tank is disturbed (for example, when the vehicle turns corners), which may result in filter blocking.

If the wax crystal sizes can be further reduced to less than 10 nanometers, the crystals settle relatively slowly and wash anti-settling can result, which leads to advantages in fuel performance compared to a fuel with settled wax crystals. If the wax crystal size can be reduced to less than about 4 nanometers, the tendency of the crystals to settle within the fuel storage period is nearly eliminated. If the crystal sizes are reduced to the preferred size of less than 2 nanometers, the wax crystals remain suspended in the fuel for the many weeks required in some storage systems and the settling problems are virtually eliminated.

25 (iv) The CFPP behavior, which was as follows:

Additive CFPP Temperature (° C) CFPP Decrease E -14 11 F -20 17 G -20 17 30 H -20 17 I -19 16 J -3 (v) The average crystal size, which was as follows: .8720496 32

Additive Size (nm) E 4400 F 10400 G 2600 5 H 10800 I 8400 J thin plates over 50,000 nm „8120498

Claims (4)

1. Use as an additive for wax-containing distillate fuel of a compound containing at least 2 substituent groups spaced and configured to occupy the positions of wax molecules in the intersection of the (001) face and the (11x) faces, For example the (110) and / or (111) faces in wax crystals, which substituent groups are alkyl, alkoxyalkyl or polyalkoxyalkyl groups with at least 10 atoms in the main chain. 2. Use according to claim 1 of a compound containing at least 2 n-alkyl groups with more than 2 carbon atoms separated by 4.5-5.5 Å. Use according to claim 1 or 2, wherein the angle between the local symmetry planes of the two n-alkyl groups is 75 - 90 °. Distillate fuel containing an additive according to claim 1.1720488