DK169213B1 - Use of an additive for waxy distilled fuel to control the size of the wax crystals formed in the distilled fuels and distilled fuel containing the additive - Google Patents

Abstract

The use as an additive for wax containing distillate fuel of a compound containing at least 2 substituent groups and having a spacing and configuration such that they may occupy the positions of wax molecules in the intersection of the (001) plane and the (110) and/or (111) planes in crystals of the wax, the substituent groups being alkyl, alkoxy alkyl or polyalkoxy alkyl having at least 10 atoms in the main chain.

Description

in DK 169213 B1

The present invention relates to the use of an additive for wax distilled fuel for controlling the size of the wax crystals in the distilled fuels. The invention further relates to a distilled fuel containing the additive.

5

Mineral oils containing paraffin wax, such as the distilled fuels used as diesel fuel and heating oil, have the property of becoming less liquid as the temperature of the oil drops. This decrease in fluidity is due to the wax being crystallized into plate-like crystals, which eventually form a sponge-like mass which encloses the oil, where the temperature at which the wax crystals begin to form is called the point of cloudiness and the temperature at which the wax prevents pouring of the oil, called the flow point.

15

It has long been known that various additives act as floating point lowering agents when mixed with waxy mineral oils. These compositions modify the size and shape of the wax crystals and decrease the cohesion between the crystals and between the wax and the oil in such a way that the oil remains liquid at a lower temperature and thus can be poured and capable of passing through coarse filters.

The literature describes various floating point lowering agents, 25 and several of which are in commercial use. In e.g. U.S. Patent No. 3,048,479 is taught about the use of copolymers of ethylene and Cj-Cg vinyl esters, e.g. vinyl acetate, as floating point lowering agents for fuels, in particular heating oils, diesel fuel and jet fuel. Also known are floating point lowering polymeric hydrocarbon compounds based on ethylene and higher α-olefins, e.g. propyl and. US Patent No. 3,252,771 relates to the use of polymers of C16'C18 ~ a-olefins with aluminum trichloride / alkyl halide catalysts as flow point lowering agents in distilled fuels of the "broad boiling" type which are easy to treat and available in United States in the 35 early 1960s.

In the late 1960s and early 1970s, greater emphasis was placed on improving the filterability of oils at temperatures between the cloud point and the floating point determined by the tougher cold filter clogging point (IP 309/80) test and CFPP, and Many patents have since been issued relating to additives to improve the fuel performance of this test. U.S. Patent No. 3,961,916 teaches the use of a mixture of copolymers to control the size of the wax crystals. In British Patent No. 1,263,152 it is proposed that the size of the wax crystals may be controlled by using a copolymer with a lower degree of side chain branching.

It is also in e.g. UK Patent No. 1,469,016 has been proposed that the copolymers of di-n-alkyl fumarates and vinyl acetate previously used as floating point lowering agents in lubricating oils can be used as co-additives with ethylene / vinyl acetate copolymers in the treatment of high distilled fuels. end boiling points 15 to improve their low temperature flow properties.

It has also been proposed to use additives based on olefinic / maleic anhydride copolymers. Eg. is used in US Patent No. 2,542,542 copolymers of olefins such as octadecene and maleic anhydride esterified with an alcohol such as 1aurylal carbon as flow point lowering agents and in UK Patent No. 1,468,588 copolymers of C22-Cgg olephios and maleic anhydride esterified with behenylal carbon as co-additives for distilled fuels. Similarly, Japanese Patent Publication No. 5,654,037 uses 25 olefin / maleic anhydride copolymers which have reacted with amines as floating point lowering agents.

In Japanese Patent Publication No. 5,654,038, the derivatives of olefin / maleic anhydride copolymers are used in conjunction with conventional 30-point improving agents for intermediate distillates such as ethylene-vinyl acetate copolymers. Japanese Patent Publication No. 5,540,640 discloses the use of olefin / maleic anhydride copolymers (not esterified) and states that the olefins used should contain more than 20 carbon atoms to achieve CFPP activity. In UK Patent Publication No. 2,192,012, mixtures of certain esterified olefin / maleic anhydride copolymers and low molecular weight polyethylene are used, the esterified copolymers being ineffective when used as the only additives.

3 DK 169213 B1

The improvement in CFPP activity obtained in these patents by the addition of the additives is achieved by modifying the size and shape of the wax crystals formed to produce mostly needle-like crystals, which generally have a particle size of 5 µm or greater, typically from about 30 µm. to 100 µm. When operating in low-temperature diesel engines, these crystals do not pass through the paper fuel filters of vehicles, 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 10 and the fuel are heated, which solution can be the main fuel is heated by recycled fuel. However, a build-up of wax can block the filters, leading to start-up problems with diesel vehicles and problems in early driving in cold weather or failure of heating systems.

15

Using a computer, it is possible to calculate the exact geometry of the n-alkane wax crystal lattice and the energetically preferred geometry of a potential additive molecule in a simple and very convenient way. The results become particularly evident when they are subsequently graphically represented by means of a plotter or graphical terminal. This method is called "molecular modeling".

Computer programs useful for this purpose are commercially available and a special usable program series is distributed by the company 25 Chemical Design Ltd., Oxford, England (Technical Manager: E.K.Davies) under the designation "Chem-X".

The growth of paraffin crystal takes place by attaching single paraffin molecules with their long side to the edge of an existing 30 paraffin plate, which is shown schematically in Figure 1. The attachment to the top or bottom of the plate is energetically unfavorable, since only one end of the paraffin chain molecule will interact. with the existing crystal in this case. The association occurs mainly in the crystallographic (001) plane (compare Fig. 2).

The 35 (001) piano contains the largest number of the strongest intermolecular bonds and thus dominates the crystal to form large, flat, rhombic plates (Fig. 3). The second most stable surface of the crystal is (lix) (eg (110)). The intermolecular association is strongest when the n-alkane molecules are closest to each other, so the (16) plate is stronger than the (100) plate.

The crystal grows by extending the (001) piano. Thus, it is important to note that the edges of this plane are the fast-advancing surfaces and these are (lix) (e.g. (110)) and to a lesser extent (100). Accordingly, growth is controlled most by the forward push of the (lix) pipe.

Since the "head-to-head" relationships are relatively weak, we generally only look at a molecular (001) piano, which is why we can assume that the (110) piano, (111) piano, and so on . are equivalent for our purpose, since the lattice jumps and the relative orientations of molecules placed side by side are the same (Figure 4).

Figure 3, which is a photograph of a wax crystal plate, shows that the macroscopic appearance of the plates is dominated by the (010) plane. It is these plates that can block filters in fuel lines in e.g. cars.

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

This can produce wax crystals with wax crystals which, at low temperatures, are of sufficient size to pass through filters typically used in diesel engines and in heating oil systems, and this is achieved by the addition of certain additives.

The present invention is directed to remedying the deficiencies of the prior art and thus relates to the use of an additive for wax hollow distilled fuel for controlling the size of the wax crystals formed in the distilled fuels which is characterized by the additive comprises a compound containing at least two substituent groups located at such a distance from each other and having such a configuration that they can occupy the wax molecule positions in the intersection of the (OO1) plane and (lix) planes, f. eg. (10) plane and / or (111) piano, in wax crystals, wherein the substituent groups are all alkyl, alkoxyalkyl or polyalkoxyalkyl containing at least 10 carbon atoms in the main chain and wherein the compound contains at least 2 n- all cooling groups having more than 2 carbon atoms where the distance between them in an energetically accessible conformation is of the order of 4.5 to 5.5 A, and where the 5-plane angle between the local symmetries is different in the two n-alkyl groups. per is from 75 ° to 90 °.

The present invention further relates to a distilled fuel which is characterized in that it contains the above additive.

10

The incorporation of the plans into the crystal can be explained with reference to Figure 4, which shows an enlarged view from above of the crystal lattice in a paraffin plate. The line of sight corresponds to the long axis of the paraffin chains. Two carbon atoms and 4 hydrogen atoms (the latter shown only once) can be seen of each paraffin molecule, since the other atoms are below the atoms shown, since all carbon atoms in one molecule are in one molecule of symmetry. It can be seen from Figure 4 that the distances between two molecules in the (100) piano and (110) piano, respectively, are practically the same.

20

These distances are designated "b" and "d" in Figure 4, and b = 4.9 A and d = 4.5 Å. The main difference between the (100) plane and (101) plane (or more rigorously (11x) plane where x is 0 or an integer) is the relative orientation of paraffin molecules which are adjacent to each other. In the (100) -pipe, molecular symmetry in the units of single molecules is parallel to each other, ie. that the top plane angle is 0 °. In the crystallographic (110) -pane, the top-plane angle between the molecular symmetry planes in adjacent molecules is approx. 82 °.

According to the invention, the additives are to occupy the paraffin molecule positions shown by "C" and "D" in Figure 4. This is only possible if the distance between the substituents is approx. from 4.5 to 5.0 A in an energetically accessible conformation, and the top plane angle between the local symmetries in the two substituents is approx. 82 °, preferably from 75 ° to 90 °.

A molecule can be formed by either entering its known atomic coordinate into a computer or by building the structure according to the chemical-physical rules using the computer. The structure can then be refined by, for example: (a) calculating the partial charges on each atom based on electronegativity differences (the force field method) or by quantum mechanical methods (e.g., CNDO, Q.C.P.E. 141, Indiana University); (b) optimizing the structure using molecular engineering (compare "Molecular Mechanics", U.Burkert and N.L.Allinger, ACS, 1982); (C) decrease the total energy by optimizing the conformation, i.e. by rotating around rotary bonds. Here, care must be taken that the environment around the wax crystal surface is different from the environment in the gas phase or in solution, and it is possible that the additive molecule co-crystallizes with the paraffin in a conformation which is not the most energetically favorable conformation in the gas phase. It must also be borne in mind that the additive cannot assume a conformation which is hindered by steric or electronic factors.

20

Using the following criteria, it can be investigated whether an additive molecule fits into the (OO1) plane of the paraffin crystal lattice at the desired positions C and D, since: (l) the distance between the substituents in the molecule must be approximately equal to the distance between two neighboring paraffin molecules in the (O1) plane which intersects the (11x) plane, i.e. ca. 4.5 Å. The relative orientation of the substituents must be aligned with the placement of the n-all channels in the (110) direction, i.e. that the two-plane angle between the local symmetries in the substituent should be approx. 82 °. The distance and angle can be easily measured using the computer programs.

(2) when the additive molecule fits into the wax crystal structure and 35 "docks" in two free grid locations.

Compounds previously proposed as additives are certain derivatives of phthalic acid, maleic acid, succinic acid and vinylidenolefins.

None of the compounds listed above meets the criterion (1) described above. This is illustrated by the following selected examples.

(a) Phthalic acid amide assumes in the best case the conformation shown in Figure 5, in which the distance between the substituents 5 is too small and the diagonal angle is too small. The conformation is energetically unfavorable due to steric hindrance. Reminime ringing leads to the disturbed conformation shown in Figure 6.

(b) The situation is similar for maleic diamide, as shown in Figure 7. Due to steric hindrance, reminimation leads to the disturbed conformation of Figure 8.

(c) Due to steric hindrance, succinic acid cannot assume a conformation which comes close to the spherical structure of the invention (compare Figure 9). When rotating about a C-C single bond, the succinic acid tilts over to the conformation shown in Figure 10.

The improvement of CFPP by incorporating 20 known additives from patents is achieved by modifying the size and shape of the formed wax crystals to produce mostly needle-like crystals, which generally have a particle size of 10,000 nm or more, typically from 30,000 to 100,000 nm. When operating on low-temperature diesel engines, these crystals do not pass the vehicle's 25 paper fuel filters, 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 fuel are heated, which can be done by the bulk fuel is heated by recycled fuel. However, a build-up of wax can block the filters, leading to start-up problems with diesel vehicles and problems initially when driving in cold weather, as well as failure of fuel heating systems.

For the present application, the following 35 study methods are used.

The fuel growth temperature (WAT) of the fuel is measured by differential scanning calorimetry (DSC). In this test, a small fuel sample (25 ml of kroliter) is cooled at 2 ° C / minute together with a reference sample 8 with similar thermal capacity, but which will not precipitate wax in the temperature range of interest (such as kerosene). An exotherm is observed when crystallization begins in the sample. The WAT of the fuel can e.g. is measured by the extrapolation method on Mettler ΤΑ 2000B.

5

The wax content of the fuel is determined from the DSC trace by integrating the area enclosed by the baseline and the exotherm down to the specified temperature. The calibration has previously been performed on a known amount of crystallizing wax.

10

The average particle size of the wax crystal is measured by analyzing a scanning electron micrograph of a fuel sample at a magnification of between 4000 and 8000 times and measuring the longest dimension of at least 40 out of 88 points on a pre-fixed grid.

We find that, assuming the average size is less than 4000 nm, the wax will begin to pass through the typical paper filters used in diesel engines, along with the fuel, although we prefer the size to be below 3000 nm, preferably below 2500, but preferably below 2000 nm and most preferably below 1000 nm, where the real benefits of passing the crystals through the paper fuel filters are achieved. The actual achievable size depends on the original nature of the fuel as well as the nature and amount of the additive used, but we have found that it is possible to obtain these sizes and smaller sizes.

25

Using the additives of the present invention, it is possible to obtain such small wax crystals in the fuel, which results in significant advantages with respect to diesel engine operation. This can be demonstrated by pumping stirred fuel through a diesel filter paper used in a VW Golf or Cummins diesel engine at 8 to 15 ml / second and 1.0 to 2.4 liters per second. per minute square meter of filter surface area at a temperature which is at least 5 ° C below the wax appearance temperature and at least 0.5% by weight of the fuel present in the form of solid wax. Both the fuel and the wax are considered to pass successfully through the filter if one or more of the following criteria is met: (i) When 18-20 liters of fuel have passed through the filter, the pressure drop across the filter does not exceed 50 kiloPascal (kPa), 9 DK B1 is preferably 25 kPa, more preferably 10 kPa, most preferably 5 kPa.

(ii) At least 60%, preferably at least 80%, more preferably at least 90% by weight of the wax present in the original fuel, as determined by the DSC test described above, is found to be present in the fuel , which leaves filter one.

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

The amount of crystals passing through the vehicle's filter and the 15 operating benefits that arise from small crystals are highly dependent on the crystal length, although the crystal shape is also significant. We find that dice-shaped crystals tend to pass more easily through the filters than flat crystals, and when they do not pass, they provide less resistance to fuel flow. Nevertheless, the preferred crystal form is a flat form, which in principle allows more wax to settle as the temperature drops and more wax precipitates before reaching the critical crystal length than is the case with a crystal of the same length in cube form.

25

The fuels obtained by the process of the present invention have unique advantages over known distilled fuels whose cold flow properties are enhanced by the addition of traditional additives. The fuels can e.g. is used at 30 temperatures near the flow point and is not limited by the inability to pass the CFPP test, as they will either pass the CFPP test at a substantially lower temperature or eliminate the need to pass this test. The fuels also have improved cold start capability at low temperatures, a capability not based on hot fuel recycling 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 traditional additives.

10 DK 169213 B1

Distilled fuel within the general class of fuels boiling from 120 ° C to 500 ° C varies substantially in boiling point properties, n-alkane distributions and wax content. Fuels from Northern Europe generally have lower final boiling points and cloudiness points than the fuels in Southern Europe. The wax content is generally greater than 1.5% (at 10 ° C below WAT). Similar fuels from other countries around the world vary in the same way, taking into account the climate, but the wax content also depends on the crude oil source. A fuel derived from a crude oil from the Middle East is likely to have a lower wax content than that derived from the waxy crude oils, such as the crude oils from China and Australia.

The extent to which it is possible to obtain very small crystals depends on the nature of the fuel itself, and in some fuels it is not possible to produce extremely small crystals. If this situation arises, the fuel properties can be modified so that it is possible to obtain such small crystals by e.g. adjusting the refining conditions and the mixture so that suitable additives can be used.

20

Most of the wax which precipitates from distilled fuel is normal all crystals which crystallize in an orthorhombic unit cell via a rotator or hexagonal form as discussed in the literature of e.g. A.Muller in Proc.Roy.Soc.A. 114 »542 (1927), same 120.

25 437, (1928), same 127, 417, (1930), same 138, 514, (1932), A.E.

Smith in J.Chem.Phys. 21, 2229 (1953) and P.W.Teare in Acta.Cryst., 12, 294, (1959). As mentioned, there are two factors that are important when adapting the additive molecule to the wax crystal structure; firstly, the separation between the n-all chain chains in selected crystal surfaces, where the most important distances to be matched are the distance in the (101) plane or direction and (111) the plane or direction, etc. and to a lesser extent in the (100) piano.

The additive chains must occupy the lattice sites (more than one) at positions 35 of the axes perpendicular to the axis of the n-alkane chains in the crystal. These distances are on the order of 4.5 to 5.5 Å, and the closer the chains of the additives are to these distances, the more effective the additive is. Second, although it may be less important, the relative orientations of the DK 169213 B1 π additive molecule chains preferably correspond to the orientations of the n-alkanes in the crystal. The n-alkyl chains on the additive must be able to closely match the intermolecular distances between the n-alkanes in the wax crystal along the (100) -pipe and / or (110) -pipe and the 5 (111) -piano. they intersect with the (001) piano, and be able to obtain conformations which enable the chains to orient themselves even at angles similar to the angles of the n-alkanes of the above-mentioned crystal. It has been found that these distances and orientations of the chains on the additive molecule can best be achieved by placing them on neighboring carbon atoms in a cyclic compound or an ethylenically unsaturated compound provided that they are in a cis-orientation.

Preferably, the matching is also obtained along the length of the n-all chain chains in 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.

The wax which precipitates from the fuel or oil is usually a series of n-all cans and is therefore referred to as average dimensions.

20

Therefore, the additives generally contain alkyl chains, preferably n -alkyl chains or chain segments which can co-crystallize with the wax. We have found that there should be 2 or more such chains per and that these should be located on the same side of the additive molecule. It is desirable that the additive molecule has two different "sides". One "side" will contain the cocrystallizable alkyl chains and the other "side" will contain the least possible number of hydrocarbon groups to block or prevent further crystallization after the additive molecule has been crystallized into the 30 n-alkane lattice sites of the wax crystals. It is also desirable that this "blocking" group be positioned halfway or about halfway down the cocrystallizable n-alkyl chains on the additive.

The additives that we prefer to use have the formula: wherein Y-R2 represents SO3 (") (+) NR3R2, -SO3 (_} (+ ) HNR3R2, -SO3 (-) (+) H2NR3R2, -SO4, OR2, -SO, NR3R2 or -SCLR2; -X-R1 is -Y-R2 or -CONR3R, -CO CoJ '^ HNRgR1, -002 ("+ +) Η ^ ν, -Co /' + + NR1, -R4-COORp -NR ^ COR1, rW, -rVoR1, -R4R1, -N (COR ^) R1 or Z 2 NR 2 R1; -Z 2 represents SO 3 or CO 2 2; R 1 and R 2 are all alkyl, alkoxyalkyl or polyalkylalkyl containing at least 10 carbon atoms in the main chain; R 3 represents hydrocarbyl and each R may be the same or different, 4 20 and R is nothing or represents C 1 to C 6 alkylene, and in: k <__ 25 c

C

B ----- ^ is the carbon-carbon bond (CC) either a) ethylenically unsaturated when A 30 and B may be alkyl, alkenyl or substituted hydrocarbyl groups, or b) a part of a cyclic structure which may be aromatic , polynuclear aromatic or cycloaliphatic.

The ring atoms of such a cyclic compound are preferably carbon atoms, but may, however, include an N, S or O ring atom to form a heterocyclic compound.

Examples of an aromatically based compound from which the additives can be prepared are:

The aromatic group of the compound may be substituted.

10

Alternatively, they can be obtained from polycyclic compounds, which are those having two or more ring structures which can take different forms. They may be (a) condensed benzene structures, (b) condensed ring structures where none or all of the rings are benzene, (c) rings bonded together "end-to-end", (d) heterocyclic compounds, (e) non-aromatic ring systems or partially saturated ring systems or (f) three-dimensional ring structures.

Condensed benzene structures from which the compounds can be derived include, e.g. naphthalene, anthracene, phenanthrene and pyrene.

The condensed ring structures where none or all of the rings are benzene include e.g. Azules, Indene, Hydroindene, Fluorene, Diphenyl and. Compounds where the rings are joined end-to-end include e.g. diphenyl. Suitable heterocyclic compounds from which the additives can be derived include, e.g. Quinoline, Pyridine, Indole, 2: 3 dihydroindole, benzofuran, coumarin, isocoumarin, benzothiophene, carbazole and thi odi phenylamine. Suitable non-aromatic ring systems or partially saturated ring systems include decal in (decahydronaphthalene), α-Pinene, cadine, bornylene. Suitable 3-dimensional compounds include e.g. norbornene, bicycloheptane (norbornane), bicyclooctane and bicyclooctene.

The two substituents X and Y must be must be attached to ring atoms adjacent to each other in the ring when there is only one ring, or to ring atoms adjacent to each other in one of the rings where the compound is polycyclic. In the latter case, this means that if naphthalene is to be used, these substituents cannot be attached to the 1,8 or 4,5 positions, but must be attached to 1,2-, 2,3-, 3, The 4-, 5.6, 6.7 or 7.8 positions.

These compounds are reacted to form esters, amines, amides, 5 semesters / half amides, half ethers or salts used as the additives. Preferred additives are the salts of a secondary amine containing a hydrogen and carbonaceous group or groups containing at least 10 carbon atoms, preferably at least 12 carbon atoms. Such amines or salts can be prepared by reacting the aforementioned acid or anhydride with an amine or by reacting a secondary amine derivative with carboxylic acids or anhydrides. Water removal and heating are usually required to prepare the amides from the acids. Alternatively, the carboxylic acid may be reacted with an alcohol containing at least 10 carbon atoms, 15 or a mixture of an alcohol and an amine.

The hydrogen and carbonaceous groups in the substituents are preferably hydrocarbyl groups, although halogenated hydrocarbyl groups can be used, preferably only with a small content of halogen atoms (e.g. chlorine atoms), e.g. less than 20% by weight. The hydrocarbyl groups are preferably aliphatic, e.g. all cool and. They are preferably unbranched. Unsaturated hydrocarbyl groups, e.g. alkenyl may be used, but they are not preferred.

The alkyl groups preferably contain at least 10 carbon atoms, preferably from 10 to 22 carbon atoms, e.g. from 14 to 20 carbon atoms, and are preferably unbranched or branched at the 1- or 2-positions. If branching exists in more than 20% of all the cooling chains, the branching must be methyl. The other hydrogen and carbonaceous groups may be shorter, e.g. less than 6 carbon atoms, or may contain at least 10 carbon atoms if desired. Suitable alkyl groups include methyl, ethyl, propyl, hexyl, decyl, dodecyl, tetradecyl, eicosyl and docosyl (behenyl). Suitable alkylene groups include hexylene, octylene, dodecylene and hexadecylene, but these are not preferred.

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

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

5!

In order to obtain the fuel of the present invention, these additives are commonly used with other additives, and examples of the other additives include those compounds called "comb" polymers having the general formula:

D H J H

• i t (* - C— C - C'— c -

II

1C E G K L

L J v.

m n where D = R, CO-OR, OCO-R, R'CO-OR or OR E = H or CH 2 or D or R '

G = H or D

m = 1.0 (homopolymer) to 0.4 (molar ratio) J = H, R ', aryl or a heterocyclic group, R'CO-OR K = H, CO-OR', OCO-R ', OR', COgH L = H, R ', CO-OR', OCO-R ', aryl, COH 2 n = 0.0 to 0.6 (molar ratio) R = C10 R' * Cj

Another monomer can be terpolymerized, if necessary.

When these other additives are copolymers of α-olefins and maleic anhydride, they can be conveniently prepared by polymerizing the monomers without solvent or in a solution of a hydrocarbon solvent such as heptane, benzene, cyclohexane or white oil, at a temperature. generally in the range of 20 ° C to 150 ° C, and usually promoted by a peroxide-type or azotype catalyst, such as benzoyl peroxide or azo-diisobutyritrile, under a blanket of an inert gas such as nitrogen or carbon dioxide. to exclude oxygen. It is preferred, but not essential, to use equimolar amounts of the olefin and maleic anhydride, although molar amounts in the range of 2: 1 to 1: 2 are suitable. Examples of olefins which can be copolymerized with maleic anhydride are: 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene.

The copolymer of the olefin and maleic anhydride can be esterified by a suitable technique, and although it is preferred that maleic anhydride is at least 50% esterified, it is not essential. Examples of 10 alcohols that may be used include n-decan-1-ol, n-dodecan-1-ol, n-tetradecan-1-ol, n-hexadecan-1-ol, n-octadecan-1-ol. The alcohols may also include up to 1 methyl branch per chain, e.g.

1-methylpentadecan-1-ol, 2-methyltridecan-1-ol. The alcohol can be a mixture of normal alcohols and alcohols with a single methyl-15 branch. Each alcohol can be used to esterify copolymers of maleic anhydride and any of the olefins. It is preferred to use pure alcohols instead of the commercially available all alcoholic breaths, but if mixtures are used, R1 refers to the average number of carbon atoms in the alkyl group if alcohols containing a branching at 1 or 2 are used. position, R * refers to the unbranched chain skeletal segment of the alcohol. When using mixtures, it is important that not more than 15% of the R 2 groups have the value R * + 2. The choice of the alcohol will of course depend on the choice of the olefin copolymerized with the maleic anhydride such that R + R * is in the range of 18 to 38. The preferred value of R + R * may depend on the boiling point properties of that fuel. , in which the additive is to be used.

These "comb" polymers may also be fumarate polymers and copolymers, such as the compounds described in our European Patent Applications Nos. 153,176, 153,177, 85,301,047 and 85,301,048. Other suitable "comb" polymers are the polymers and copolymers of α-olefins and the esterified copolymers of styrene and maleic anhydride.

35

Examples of other additives which may be used with the cyclic compound are the polyoxyalkyl enesters, ethers, esters / ethers and mixtures thereof, in particular those additives containing at least one, preferably at least 2 unbranched, saturated Μ I * 1. 1 1 ............

17 DK 169213 B1

C 10 -C 30 alkyl groups and a polyoxyalkylene glycol group having a molecular weight of from 100 to 5000, preferably from 200 to 5000, wherein the alkyl group in the polyoxyalkylene glycol contains from 1 to 4 carbon atoms. These materials are disclosed in European Patent No. 61.895 5 B. Other such additives are disclosed in U.S. Patent No. 4,491,455.

The preferred esters, ethers or esters / ethers useful in the present invention may be depicted structurally by the formula: R-O (A) -O-R "wherein R and R" are the same or different and may be i) n -alkyl ii) n -alkyl-C (= O) iii) n -alkyl-O-C (= O) - (CH 2) n-iv) n -alkyl-O-C (= O ) - (CH 2) n C (= O) - 20 wherein the alkyl group is unbranched and saturated and contains from 10 to 30 carbon atoms and A represents the polyoxyalkylene segment of the glycol wherein the alkylene group contains from 1 to 4 carbon atoms such as the polyoxymethylene, polyoxyethylene or polyoxytrimethylene moiety , 25 which is substantially unbranched; any degree of branching with lower alkyl side chains (such as in polyoxypropylene glycol) can be tolerated, but it is preferred that the glycol be substantially unbranched, A may also contain nitrogen.

Suitable glycols are generally the substantially unbranched polyethylene glycols (PEG) and polypropylene glycols (PPG) having a molecular weight of about 100 to 5000, preferably from ca. Esters are preferred and fatty acids containing 10 to 30 carbon atoms are useful for reaction with the glycols to form the 35 ester additives, and it is preferred to use a C C-C ^ fatty acid, especially behenic acids. The esters can also be prepared by esterifying polyethoxylated fatty acids or polyethoxylated alcohols.

Polyoxyalkylene diesters, diets, ethers / esters and mixtures thereof are suitable as additives, where the diesters are preferred for use in distillates with a narrow boiling range, although smaller amounts of mono ethers and monoesters may also be present and often formed in the manufacturing process. . It is important for the ability of the additive that a substantial amount of the alkyl compound be present. Particularly preferred are stearic and behenic acid esters or polyethylene glycol, polypropyl englycol or polyethylene / polypropylene glycol bl breaths.

The additives used may also contain ethyl monounsaturated, flow-enhancing ester copolymers. The unsaturated monomers which may be copolymerized with ethyl one include unsaturated mono and di esters of the general formula:

H

c = c 20 R 5 → r 7 where R g represents hydrogen or methyl, R g represents an -OOCRg group, where Rg represents hydrogen or an unbranched or branched C C-C ^ alkyl group, usually a Cj-C ^. -alkyl group and preferably a C 1 -C 6 alkyl group, or R g represents a -COORg group wherein Rg has the meaning previously defined but is not hydrogen and Ry is hydrogen or -COORg as defined above. The monomer when Rg and R7 represent hydrogen and Rg represents -00CRg includes vinyl alcohol esters of C1 "C29 monocarboxylic acids, usually C2-C8 monocarboxylic acids and preferably C2" C2g monocarboxylic acids, usually C1- and preferably C 2 -C 8 monocarboxylic acids. Examples of vinyl esters which can be copolymerized with ethyl one include vinyl acetate, vinyl propionate and vinyl butyrate or isobutyrate, where vinyl acetate is preferred. When used, we prefer that the copolymers contain from 5 to 40% by weight of the vinyl ester, more preferably from 10 to 35% by weight of the vinyl ester. They may also be mixtures of two copolymers, such as those described in U.S. Patent No. 3,961,916. It is preferred that these copolymers have a mean molecular weight number measured by vapor phase osmometry of from 1000 to 10,000, preferably from 1000 to 5000.

The additives used may also contain other polar compounds, either ionic or nonionic, which in fuels have the ability to act as wax crystal growth inhibitors. Polar nitrogen-containing compounds have been found to be particularly effective when used with the glycol esters, ethers or esters / ethers. These polar compounds are generally amine salts and / or amides 10 formed by reacting at least one mole of hydrocarbyl substituted amines with one mole of hydrocarbyl acid containing from 1 to 4 carboxylic acid groups, or anhydrides thereof; esters / amides containing from 30 to 300 carbon atoms can be used, preferably from 50 to 150 carbon atoms. These nitrogen compounds 15 are described in U.S. Patent No. 4,211,534. Suitable amines are usually long chain, primary, secondary, tertiary or quaternary C C-C ^ amines or mixtures thereof, but shorter chain amines can be used provided that the nitrogen compound in question is oil soluble and therefore usually contains from 30 to 300 carbon atoms in total. -20 am. The nitrogen compound preferably contains at least one unbranched C C-C-alkyl alkyl segment.

Suitable amines include primary, secondary, tertiary or quaternary amines, but secondary is preferred. Tertiary and quaternary 25 amines can only form amine salts. Examples of amines include tetradecylamine, cocoamine, hydrogenated tallow amine and the like. Examples of secondary amines include dioctacetylamine, methylbehenylamine and the like. Amine blends are also suitable and many amines derived from natural materials are blends. The preferred 30 amine is a secondary hydrogenated tallow amine of the formula HNRjRg wherein R 1 and R 2 represent alkyl groups derived from hydrogenated sebum fat composed of approx. 4% C₂, 31% C₂, and 59% C₂g.

Examples of suitable carboxylic acids (and their anhydrides) for the preparation of these nitrogen compounds include cyclohexane-1,2-di-carboxylic acid, cyclohexene-1,2-di-carboxylic acid, cyclopentane-1,2-di-carboxylic acid, naphtha endicarboxylic acid and the like. Generally, these acids will have approx. 5-13 carbon atoms in the cyclic moiety. Preferred acids useful in the present invention are benzenedicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid. Phthalic acid and its anhydride are particularly preferred. The particularly preferred compound is the amide-amine salt which is formed by the reaction of 1 mole of phthalic anhydride with 2 moles of hydrogenated tallow amine. Another preferred compound is the di amide which is formed by dehydrating this amide-amine salt.

Hydrocarbon polymers can also be used as part of the additive combination to produce the fuels of the invention. These 10 can be represented by the following general formula: r 1 Γ ^

T H UH

- C - C - C - C-- 15

T T HU

L J L

V V

Where T = H or R '20 U = Η, T or aryl v = 1.0 to 0.0 (molar ratio) w = 0.0 to 1.0 (molar ratio) where R' represents all cooling.

25

These polymers can be prepared directly from ethylenically unsaturated monomers or indirectly, e.g. hydrogenating the polymer prepared from other monomers such as in soprene and butadiene.

A particularly preferred hydrocarbon polymer is a copolymer of ethyl one and propyl one having an ethylene content, preferably between 50 and 60% (w / w).

The amount of additive required to prepare the distilled 1-35 gelled fuel oil of the present invention will vary depending on the fuel, but is generally from 0.001 to 0.5% by weight, e.g. from 0.01 to 0.1% by weight (active substance) based on the weight of the fuel. The additive may conveniently be dissolved in a suitable solvent to form a concentrate of from 20 to 90% by weight, e.g. from 30 to 80% by weight in the solvent. Suitable solvents include kerosene, aromatic naphthas, mineral lubricants, etc.

The present invention is illustrated by the following examples in which the size of the wax crystals in the fuel is measured by placing samples of fuel in 57 g bottles in cold boxes kept at 8 ° C above the fuel cloud point for 1 hour while the fuel temperature stabilizes. The box is then cooled at 10 1 ° C per hour down to the test temperature where it is then kept.

A pre-made filter carrier consisting of a 10 mm diameter sintered ring surrounded by a 1 mm wide annular metal-15 ring supporting a 200 nm silver membrane filter, which is held in place by two vertical needles, is placed then on a vacuum unit. A vacuum of at least 80 kPa is applied and the cooled fuel is dripped onto the diaphragm from a clean drip diplet until a small dome-shaped puddle just covers the diaphragm.

The fuel is slowly dripped to maintain the puddle for a few minutes; after approx. 10-20 drops of fuel had been applied, allowing the puddle to drain away leaving a thin, matte layer of damp fuel wax cake on the membrane. A thick layer of wax will not be acceptable to wash and a very thin layer can be washed. The optimum layer thickness is a function of the crystal shape, where "leafy" crystals need thinner layers than "small-knotted" crystals.

It is important that the final cake has a matte appearance. A "shiny" cake indicates excess residual fuel and crystal "smearing" and should be discarded.

30

The cake is then washed with a few drops of methyl ethyl ketone, which is allowed to drain completely. The process is repeated a number of times.

When the wash is done, the methyl ethyl ketone will disappear very quickly leaving a "brilliant-math white" surface which will turn gray upon application of another drop of methyl ethyl ketone.

The washed sample was then placed in a cold desiccator and kept there until coated in the SEM assay. It may be necessary to keep the sample cool to preserve the wax, in which case it should be stored in a cold box prior to transfer (in a suitable sample transfer container) to the SEM assay to avoid ice crystal formation on the sample surface.

5 During coating, the sample should be kept as cold as possible to minimize the damage to the crystals. Electrical contact with the object table is best provided with a holding screw, which presses the ring to the side of a well in the object table, which is designed so that the sample surface can lie in the instrument focal plane. An electrically conductive coating can also be used. After coating, the hook frames are obtained in the conventional manner on the scanning electron microscope. The photomi hook frames were analyzed to determine the average crystal size by attaching a transparent 88-point sheet (as spots) to the cuts in a regular, evenly spaced grid of 8 rows and 15 11 bars for a suitable microgram. The magnification should be such that only a few of the largest crystals are affected by more than one spot, and a magnification of 4000 - 8000 times has proven to be suitable.

At each grid point where the stain touches a crystal whose shape can be easily delimited, the crystal can be measured. A measure of "spread" in the form of a Gaussian standard deviation of the crystal length using Bessel correction is also taken.

The wax content before and after the filter was measured using a differential scanning calorimeter DSC (such as the du Pont 9900 series), which is capable of producing an image having an area of about

2 100 cm / 1% wax in the fuel with a noise induced instrument output variation with a standard deviation of less than 2% of the average output signal.

The DSC was calibrated using an additive to form large crystals that were assured to be removed by the filter, examined this calibration fuel at the test temperature of the equipment, and measured the growth sensing temperature of the thus-depleted fuel on the DSC. The tank fuel and fuel 35 samples after filtration to be examined are then analyzed on the DSC, and for each fuel, the area above baseline down to the calibration fuel boiler temperature was determined.

rnv.Lnlf1o + DSC area for the sample after filtration 1nfW The increased DSC area for the tank sample x 100 / ° 23 DK 169213 B1 is the percentage of wax left after the filter.

The cloud point of the distilled fuels was determined by the cloud standard test (IP-219 or ASTM-D 2500), and other targets for initial crystallization are the Growth Vision Point (WAP) test (ASTM D.3117-72) and the Growth Viscosity Temperature (WAT) measured. differential scanning calorimetry using a Mettler ΤΑ 2000B differential scanning calorimeter.

The ability of the fuel to pass through a main filter of a diesel car was determined in an apparatus consisting of a typical main filter of a diesel car placed in a standard assembly in a fuel line; The Bosch type used in a 1980 VW Golf di donkey passenger car and a Cummins FF105 used in the Cummins NTC series are appropriate. A reservoir and feed system capable of supplying half of a normal fuel tank with fuel connected to a fuel injection pump as used in the VW Golf was used to draw fuel through the filter from the tank at a constant flow rate as in the car. Instruments are provided for measuring the pressure drop across the filter, the flow rate from the injection pump, and the unit temperatures. Containers are provided to receive the pumped fuel, both the "injected" fuel and surplus fuel.

25 By the test ring, the tank was filled with 19 kg of fuel and was leak tested. When this was satisfactory, the temperature was stabilized at an air temperature of 8 ° C above the fuel cloud point. The unit was then cooled at 3 ° C / hour to the desired test temperature and kept there for at least 3 hours to stabilize the fuel temperature. The tank is shaken vigorously to completely disperse the wax present; a sample is taken from the tank and 1 liter of fuel is removed through a sampling point on the discharge line immediately after the tank and returned to the tank. The pump is restarted at the pump speed per minute. 35 minutes equal to revolutions per minute. pump speed at a road speed of 110 km / h (110 kph). In the case of the VW Golf, this is 1900 rpm. which corresponds to an engine speed of 3800 rpm. minute. Pressure drop across the filter and fuel flow rate from the injection pump are measured until the fuel is exhausted, typically from 30 to 35 minutes.

Provided that the fuel supply to the injectors can be kept at 2 ml / sec. (excess fuel will be about 6.5 - 7 ml / sec.) the result is "PASSED". A decrease in feed fuel flow to injectors indicates a "BORDER LINE" result; no power a "FAILED".

A "PASSED" result is typically associated with an increasing pressure drop across the filter, which can rise to as much as 60 kPa.

In general, considerable quantities of wax must pass through the filter in order to achieve such a result. A "GOOD PASSAGE" is characterized by a process in which the pressure drop across the filter does not exceed 10 kPa and is the first indication that most of the wax has passed through the filter, an excellent result having a pressure drop below 5 15 kPa.

In addition, fuel samples are taken from the "surplus" fuel and the "injection food" fuel, ideally every 4 minutes during the test. These samples are compared with samples from the tank before the 20 tests at DSC to determine the proportion of wax passed through the filter. Samples are also taken from the fuel prior to the test and SEM samples are prepared from them after the test to compare wax crystal size and type with actual capacity.

The following additives were used.

Additive 1 N, N-dialkyl the ammonium salt of 2-dialkylamidobenzenesulfonate, where all the alkyl groups are nCjgjg ^ 33.37 »prepared by reacting 1 mole of cyclic anhydride of orthosulfobenzoic acid with 2 moles of di- (hydrogenated) talgamine in a xylene solvent at a concentration of 50% (w / w). The reaction mixture was stirred between 100 ° C and the reflux temperature. The solvent and chemicals should be stored as dry as possible so that the anhydride is not hydrolyzed.

The product was analyzed by 500 MHz nuclear magnetic resonance spectroscopy, which confirmed that the structure was: C-N (CH2 - (CH2) 14 / 16CH3) 2 '.....

SO 3 NH (+> ((CH 2 (-CH 2) 14/16 CH 3) 2 10)

The molecular model for this compound is shown in Figure 11.

Additive 2

A copolymer of ethyl one and 17% by weight vinyl acetate had a molecular weight of 1500 and a side chain branching of 8 methyl groups per 100 methylene groups measured at 500 MHz NMR.

Additive 3

A styrene-dialkyl maleate copolymer prepared by esterification of a 20 styrene-maleic anhydride copolymer (1: 1 molar ratio) with 2 mol of a mixture of C12H25OH and C14 ^ 2901 ^ (1: 1 ratio 1). mole of anhydride group (a small excess, 5% alcohol was used) using p-toluenesulfonic acid as catalyst (1/10 mole) in xylene solvent, giving a molecular weight (average number) of 50,000 and a content of 3% (w / w) unreacted alcohol.

Additive 4

These all cool the ammonium salts of 2-N, N-dialkylamidobenzoate, prepared by mixing 1 mole of phthalic anhydride with 2 moles of dihydrogenated tallow at 60 ° C.

The results were as follows:

Example 1 Fuel Properties

Cloudy point -14 ° C

5 Growth appearance temperature -18.6 ° C

Initial boiling point 178 ° C

20% 230 ° C

90% 318 ° C

Final boiling point 355 ° C

Wax contents at -25 ° C 1.1 wt% 250 ppm of each of the additives 1, 2 and 3 were added to the fuel and the test temperature was -25 ° C. The wax crystals were found to be 1200 nm in length and over 90% by weight of the wax passed through the Cummins FF105 filter.

During the test, the passage of wax was further detected by observing the pressure drop across the filter, which increased only by 2.2 kPa.

Example 2

Example 1 was repeated and the wax crystal size was found to be 1300 nm and the maximum final pressure drop across the filter was 3.4 kPa.

Example 3

Fuel characteristics.

Cloudy point 0 ° C

Growth appearance temperature -2.5 ° C

Initial boiling point 182 ° C

20% 220 ° C

90% 354 ° C

Final boiling point 385 ° C

Wax contents at the test temperature 1.6 wt% 250 ppm of each of the additives 1, 2 and 3 were used and the wax crystal size was found to be 1500 nm, and approx. 75% by weight of the wax had passed through the Bosch 145434106 filter at the test temperature of -8.5 ° C. The maximum pressure drop across the filter was 6.5 kPa.

Example 4 Example 3 was repeated and found to give a wax crystal size of 2000 nm and approx. 50% by weight of the wax passed through the filter, giving a maximum pressure drop of 35.3 kPa.

Example 5 The fuel used in Example 3 was treated with 400 ppm

Additive 1 and 100 ppm of a mixture of Additive 2 and tested as in Example 3 at -8 ° C, at which temperature the wax content was 1.4% by weight. The wax crystal size was found to be 2500 nm and 50% by weight of the wax passed through the filter with a maximum final pressure drop of 67.1 kPa.

When this fuel was used in the test equipment, the pressure drop increased rather quickly and the test failed. We believe this is because, as shown in the photograph, the crystals are flat, and flat crystals that do not pass through the filter tend to cover the filter with a thin impervious layer. "Cube" (or "nodular") crystals, on the other hand, when they do not pass through the filters, accumulate in a relatively loose "cake" through which the fuel can still pass until the mass 25 becomes so large that the filter becomes filled up. , and the total thickness of the wax "cake" is so large that the pressure drop is again too great.

Example 6 (Comparative Example)

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 tested at -8 ° C where the wax crystal size was found to be 6300 nm and 13% by weight of the wax had passed through the filter.

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

A scanning electron micrograph of the wax crystals formed in the fuels of Examples 1 to 6 is reproduced in Figures 1 to 6.

28 DK 169213 B1

Examples 1-4 show, therefore, that crystals can pass through the filter reliably and that excellent ability at cold temperature can be extended to much higher wax content of the fuel than has hitherto been practiced, and also at temperatures further below the growth point of entry. than has been practiced so far. This applies without regard to the fuel system, such as the possibility that recycled fuel from the engine can heat the feed fuel taken from the fuel tank, the ratio of feed fuel flow to recycled fuel, the ratio of the main filter surface area to the feed fuel flow, and the size and position of the prefilter.

These examples show that, for the tested filters, crystal lengths of less than ca. 1800 nm in a significantly improved fuel capacity.

Example 7 In this example, Additive 1 was added to a distilled fuel having the following properties:

Initial boiling point 180 ° C

20% 223 ° C

90% 336 ° C

Final boiling point 355 ° C

Growth emergence temperature 5.5 ° C

Cloudy point -3.5 ° C

For comparison, the following additives were also added to the distilled fuel:

Additive A: A mixture of ethylene / vinyl acetate copolymers, one of which 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 (average number) of 2000, a side chain branching of between 2 and 3 methyl groups per

100 methylene groups measured at 500 MHz NMR.

Additive B: A mixture of additives 4 and 2 where the molar ratio was 5 4: 1.

29 DK 169213 B1

Additive C: The dibehenate of a polyethylene glycol bl breath with an average molecular weight of 600.

Additive D: An ethylene / propylene copolymer in which the ethylene content was 56 wt% and the average number molecular weight was approx. 60,000.

The additives were added in the quantities shown in the following table and the tests were performed according to PCT, the details of which are as follows:

Programmed Cooling Test (PCT)

This is a slow cooling test designed to correlate with the pumping of a stored heating oil. The cold flow properties of the fuel containing the additives are determined by the PCT as follows: 300 ml of fuel is cooled linearly at 1 ° C / hour to the test temperature and then the temperature is kept constant. After two hours at the test temperature, approx. 20 ml of the surface layer at 20 aspirations to prevent the test from being affected by the abnormally large wax crystals which tend to form on the interface between oil and air during cooling.

Wax, which is precipitated in the bottle, is dispersed by gentle stirring and then a CFPPT® filter unit is inserted. The tap is opened to apply a vacuum of 500 mm Hg and closes when 200 ml of fuel has passed through the filter into the graduated receiver container:

A "PASSED" is indicated if the 200 ml is collected within 10 seconds through a given mesh size, or a "FAILED" if the flow rate is small, indicating that the filter has been blocked.

The mesh number passed at the test temperature is indicated.

(L) CFPPT - Cold Filter Clogging Point Test (CFPPT) described in detail in "Journal of the Institute of Petroleum", vol.52, no.510, June 1966, pp.173-185.

30 DK 169213 B1

Example 8

The fuel used in this example had the following characteristics: 5 (ASTM-D86)

Initial boiling point 190 ° C

20% 246 ° C

90% 346 ° C

Final boiling point 374 ° C

10 Growth Ice Age temperature -1.5 ° C

Cloudy point + 2.0 ° C

It was treated with 1000 parts per million active ingredients of the following additives: 15 (E) A mixture of additive 2 (1 part by weight) and additive 4 (9 parts by weight).

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

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

1 part additive D

25 1 part additive K

(H) The commercial ethylene vinyl acetate copolymer additive sold by Amoco as 2042E.

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

(J) No additive 35 (K) The reaction product of the reaction between 4 moles of hydrogenated number of gamine and 1 mole of pyromellitic anhydride. The reaction was carried out without solvent at 150 ° C with stirring under nitrogen for 6 hours.

31 DK 169213 B1 The following performance characteristics of these fuels were then measured: (i) The fuel's ability to pass through the diesel fuel head filter at -9 ° C and the percentage of wax passing through the filter were as follows:

Additive Time to failure% wax passing E 11 minutes 18-30% 10 F 16 minutes 30% G Failed 90-100% H 15 minutes 25% I 12 minutes 25% J 9 minutes 10% 15 (II) Pressure drop over main filter plotted against time and the results are shown graphically in Figure 12.

(iii) Wax precipitation in the fuels was measured by cooling 100 20 ml of fuel in a graduated measuring vessel. The vessel was cooled at 1 ° C / hour from a temperature which was preferably 10 ° C above the fuel cloud point but not less than 5 ° C above the fuel cloud point until the test temperature maintained for the prescribed time. The test temperature and temperature equilibrium time depended on the application, ie. diesel fuel and heating oil.

It is preferred that the test temperature be at least 5 ° C below the cloud point and that the minimum cold settling time at the test temperature be at least 4 hours. Preferably, the test temperature should be at least 10 ° C or more below the cloud point of fuel and the temperature equalization period should be 24 hours or more.

After the temperature equalization period, the measuring vessel was examined and the amount of wax crystal precipitation was measured visually as the height of any wax layer above the bottom of the vessel (0 ml) and was expressed as 35% of total volume (100 ml). Clear fuel can be seen over the precipitated wax crystals, and this measurement form is often sufficient to assess the wax precipitation.

Sometimes the fuel is unclear over a precipitated wax crystal layer, or it can be seen that the wax crystals are visibly closer, as they approach the bottom of the container. In this case, a more quantitative method of analysis is used. Here the top 5% (5 ml) of the fuel is carefully absorbed and stored, the next 45% is sucked and discarded, the next 5% is sucked and stored, the next 35% is sucked and 5 discarded, and finally the 10% is collected at the bottom after heating to dissolve the wax crystals. These stored samples will therefore be referred to as top, middle and bottom samples respectively. It is important that the applied vacuum to remove the samples is rather low, i.e. 200 mm of water pressure and that the top of the pipette is placed precisely on the surface of the fuel to avoid flow in the liquid which could interfere with the concentration of wax in different layers in the container. The samples are then heated to 60 ° C for 15 minutes and examined for wax contents by differential scanning calorimetry (DSC) as previously described.

15 In this case, a Mettler ΤΑ 2000B DSC machine was used.

A 25 ml sample was placed in the sample cell and plain kerosene in the reference cell, after which they were cooled at 22 ° C / minute from 60 ° C to at least 10 ° C above the growth temperature (WAT), but preferably 20 ° C above that. temperature, then cooled at 2 ° C / minute to approx. 20 ° C below the growth temperature. A reference must be made to the non-precipitated, uncooled, treated fuel. The degree of wax precipitation then correlates with the growth stage 1 appearance temperature (or WWAT = WAT in the precipitated sample -25 WAT initially). Negative values indicate dewaxing of the fuel and positive values indicate wax enrichment during settling. The wax content can also be used as a measure of precipitation from these samples. This is illustrated by% wax or W% wax (W% wax =% wax in the precipitated sample -% wax initially), and again 30 indicates negative values of dewaxing of the fuel, and positive values indicate wax enrichment by settling.

In this example, the fuel was cooled at 1 ° C / hour from + 10 ° C to -9 ° C and was cold-cooled for 48 hours prior to testing.

The results were as follows: 33 DK 169213 B1

Growth path 1Secure temperature

Visual wax (° C) in precipitated samples

Additive settling Upper 5% Middle 5% Lower 10% E unclear -10.80 -4.00 -3.15 5 all the way Closer at the bottom F 50% clear -13.35 -0.80 -0.40 above G 100 % -7.85 -7.40 -7.50 10 H 35% clear -13.05 -8.50 +0.50 above I 65% clear J 100% semi-gel -6.20 -6.25 -6.40 15 (the results are also shown graphically in Figure 13).

Initial Growth Visibility Temperature 20 Growth Visibility Temperature (Non-precipitated _ (° C) (Precipitated Specimens) _ Fuel) Upper 5% Middle 5% Lower 10% E -6.00 -4.80 +2.00 + 2.85 F - 5.15 -8.20 +4.35 +4.75 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 (note that a significant decrease in growth appearance temperature can be achieved by the most effective additive (G)).

_% Wax (precipitated samples) _ Upper 5% Middle 5% Lower 10% E -0.7 + 0.8 + 0.9 35 f -0.8 + 2.1 + 2.2 G% 0.0 + 0.3 + 0.1 H -1.3 -0.2 +1.1 J -0.1 ± 0.0 ± 0.1 34 DK 169213 B1

These results showed that when the crystal size was reduced in the presence of the additives, the wax crystals precipitated relatively quickly. Eg. when treated below their cloud point, untreated fuels tend to show little wax crystal precipitation because the plate-like crystals intervene and cannot fall freely in the liquid, and a gel-like structure is built up but when a floating point enhancement is added. The crystals can be modified so as to have less tendency to form plates and tend to form 10 needles of sizes in the vicinity of a tens of microns, which can move freely in the liquid and settle relatively quickly. This wax crystal precipitation can cause problems in storage tanks and automotive systems. Concentrated wax layers can be unexpectedly drawn, especially when the fuel level is low or the tank is disturbed (eg when a car is running around corners) and filter blocking can occur.

If the wax crystal size can be further reduced to less than 10 nm, the crystals settle relatively slowly and there may be a 20 wax antibody precipitate which provides advantages in fuel function compared to a fuel with precipitated wax crystals. If the wax crystal size can be reduced to less than approx. 4 nm, the tendency of the crystals to settle is almost eliminated within the time the fuel is stored. If the crystal size is reduced to the preferred size of less than 2 nm, the wax crystals remain suspended in the fuel for the many weeks needed in some storage systems and the settling problems are substantially eliminated.

(Iv) The following results are obtained with respect to CFPP:

Additive CFPP temperature f ° Cl CFPP lowering E -14 11 F -20 17 35 G -20 17 H -20 17 I -19 16 J -3 35 DK 169213 B1 (v) The average crystal size was found to be:

Additive Size (nanometer) E 4400 5 F 10400 G 2600 H 10800 I 8400 J Thin plates over 10 50000.

15 20 25 30 35

Claims (2)

36 DK 169213 B1 Use of an additive for wax-distilled fuel for controlling the size of the wax crystals formed in the 5 distilled fuels, characterized in that the additive comprises a compound containing at least two substituent groups present at such a distance apart and have such a configuration that they can occupy the wax molecule positions in the intersection of the (001) piano and (11x) planes, e.g. (10) plane and / or 10 (111) -pane, in wax crystals wherein the substituent groups are all alkyl, alkoxyalkyl or polyalkoxyalkyl containing at least 10 carbon atoms in the main chain and wherein the compound contains at least 2 n -alkyl groups having more than 2 carbon atoms where the distance between them in an energetically accessible conformation is of the order of 15 from 4.5 to 5.5 Å and where the 2-plane angle between the local symmetry planes of the two n-alkyl groups is from 75 ° to 90 °. Distilled fuel, characterized in that it contains an additive according to claim 1. 20 25 30 35