NL8720511A - 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

* 8720511 VO 1137

Middle distillate compositions with reduced wax crystal size.

The invention relates to improved distillate fuel oil.

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 fluidity loss is due to the crystallization of the wax in the form of plate-like crystals, which eventually form a spongy mass, in which the oil is enclosed. The temperature at which the wax crystals begin to form is known as the " cloud point "and the temperature at which the wax prevents the pouring of the oil as the" pour point ".

It has long been known that various additives act as pour point depressants when mixed with paraffin wax-containing mineral oils. 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 can remain liquid at a lower temperature and thereby remain pourable and pass through coarse filters.

Various pour point depressants have been described in the literature and some of them are used commercially. For example, U.S. Pat. No. 3,048,479 teaches the use of copolymers of ethylene and C 1 -C 4 vinyl esters, for example, vinyl acetate, as pour point depressants for fuels, especially heating oils, diesel and jet fuels. Hydrocarbon polymeric pour point depressants based on ethylene and higher olefins, eg propylene, are also known. US Pat. No. 3,252,771 relates to the use of polymers of C18C18g olefins-1 with aluminum trichloride / alkyl halide catalysts as pour point depressants in distillate fuels of the "wide boiling" types which are easy to treat, those in the early 1960s in the United States

States were available. In the later 1960s and early 1970s, greater emphasis was placed on improving the filterability of 6 §72 OS 1 f «2 oils at temperatures between the cloud point and pour point, as determined by the more stringent Cold Filter Plugging Point ( CFPP) Test (IP 309/80), and since then many patents have been issued relating to 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. In UK patent 1,263,152 it is proposed that the size of the wax crystals can be controlled by using a copolymer with less side chain branching.

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

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 octa-20 decene, with maleic anhydride, esterified with an alcohol such as lauryl alcohol, are used as pour point depressants, and according to UK Patent 1,468,588, copolymers of C22 -C28 ones with maleic anhydride, esterified with behenyl alcohols, used as auxiliary additives for distillate fuels. Likewise, 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 together with conventional mid-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 used should contain 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, which esterified copolymers are ineffective, are used. when they are used as the only additives.

The improvement in CFPP activity obtained by using the additives according to said patent is achieved by modifying the size and shape of the wax crystals that form into mostly needle-like crystals, generally with a particle size of 10,000 nanometers or more, typically 30,000-100,000 nanometers. During diesel engine operation at low temperatures, these crystals are not passed through the paper fuel filters, but these crystals form a permeable cake on the filter, which allows the liquid fuel to pass, which wax crystals will dissolve later when the engine and fuel are warmer as can be the case by heating up the fuel mass by recycled fuel. However, the build-up of wax can block the filters, leading to diesel vehicle starting problems and problems in starting cold weather driving, and can also lead to failure of fuel heating systems.

It has now surprisingly been found that wax wax-containing fuels with wax crystals of sufficiently small size at low temperatures to pass through main paper filters typically used in diesel engines can be obtained by the addition of certain additives.

The invention therefore provides distillate fuel oil, boiling in the range of 120 ° C to 500 ° C, which has a wax content of at least 0.5% by weight at a temperature of 10 ° C below the 25 Wax Appearance Temperature, which wax crystals at that temperature have an average particle size of less than 4000 nanometers.

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 / min along with a reference sample with a similar thermal capacity, but which does not precipitate wax in the temperature range of interest (eg kerosene). An exotherm is observed when crystallization in the sample begins.

For example, the WHAT of the fuel can be measured using the extra-35 polishing technique on a Mettler TA 2000B Differential Scanning Calorimeter.

The wax content of the fuel is derived from the DSC graph by integrating the surface enclosed by the base line and the exotherm to the specified temperature. Calibration was previously performed on 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 between 4000 and 8000, measuring the longest dimension of at least 40 out of 88 points on a preselected grid. It has been found that at an average size of less than 4000 nanometers, the wax begins to pass through the typical paper filters used in diesel engines along with the fuel, but preferably the size is less than 3000 nanometers, more preferably less than 2000 nanometers, in particular even less than 1500 nanometers and most preferably less than 1000 nanometers, where the real advantage of passage of the crystals through the paper fuel filters is achieved. The actual achievable size depends on the origin of the fuel and the nature and amount of the additive used, but it has been found that these dimensions are smaller and achievable.

The ability to obtain such small wax crystals in the fuel results in a significant advantage in the utility of diesel engines. 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 an amount of 8-15 ml / sec and 1.0 - 2.4 l / min per mz filter surface at a temperature of at least 5 ° C below the WAT with at least 0.5 wt% of the fuel present in the form of solid wax. Fuel and wax are considered to pass through the filter successfully if one or more of the following criteria are met.

(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, most preferably no greater than 5 kPa .

(ii) At least 60% by weight, preferably at least 80% by weight, especially at least 90% by weight, of the wax contained in the original fuel, determined according to the DSC test described previously, is present in the fuel, which filter.

(iii) During pumping of 18 - 20 1 fuel through the filter, the flow rate always remains above 60% and preferably above-80% of the original flow rate.

The portion of the crystals that pass through the vehicle filter, and the utility advantage, which results from small crystals, are highly dependent on crystal length, although o-crystal shape is important. It has been found that cube-like crystals are somewhat easier to pass through filters than flat crystals and, when not passed, are less resistant to fuel flow. Nevertheless, the preferred crystal shape is a flat shape, which basically allows more wax to be deposited as the temperature drops, so that more wax precipitates before the critical crystal length is reached than is the case with a crystal of the same length in cubic form.

The fuels 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. The fuels also exhibit an improved cold start 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 and not to settle and form waxy layers in storage tanks, as is the case with fuels treated with conventional additives to provide distribution benefits. In addition, the fuels often have improved usability in the Cold Climate 25 Chassis Dynamometer Test compared to fuel containing conventional additives. In many cases the fuels also show an improved CFPP behavior.

Distillate fuels in the general class of those boiling between 120 and 500 ° C differ markedly in their cooking properties, n-alkane distribution and wash contents. Fuels out

Northern Europe generally has lower final boiling points and cloud points than fuels in Southern Europe. The wash contents are generally greater than 1.5% (at 10 ° C below the WAT). Likewise, fuels from other countries of 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 crude oil from the Middle East will have a lower wax content than a fuel derived from one of the paraffin wax-containing crudes from China and Australia.

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

The preferred additives are compounds of the general formula 1 depicted on the formula sheet, wherein 15 -Y-R2 is CO (+) NR3R2, -SO, (- ^ +) HNR3R2 J 3 ^ 2 qn (-) (+) „„ 3.2 ςη (-) (+) _ 2 -SO ^ H2NR R '~ S ° 3 H ^ NR' 3 2 2 -S02NR R or “S03R; 1 2 3 1 -XR is -YR or -CONR R, -co2 (-) (+) nr3r1, -co2 (_) (+) hnr3r1, 20 -co2 (+) h2nr3r1, -co2 (-) (+) h3nr1, -r4 -coor1, -nr3cor1,4 1 4 1 4 1 R OR, -R OCOR, -RR, -N (COR3) R1 or Z (_) ^ NR ^ R1; -Z {_) is SO3 (_) or -CO2 (-); 1 2 25 R and R represent alkyl, alkoxyalkyl or polyalkoxyalkyl having at least 10 carbon atoms in the main chain; 3 3 R is a hydrocarbon group, where each R can be the same or different 4, and R is nothing or C -Cj. alkylene, and in the molecular portion of formula 2 the carbon-carbon (CC) bond is either a) ethylenically unsaturated when A and B are alkyl, alkenyl or substituted hydrocarbon groups, or b) are part of a cyclic structure, which may be aromatic, multi-nuclear aromatic or cycloaliphatic, including. It is preferred that X-R and Y-R together contain at least three alkyl, alkoxyalkyl or polyalkoxyalkyl groups.

The ring atoms in such a cyclic compound are preferably carbon atoms, but may contain a ring nitrogen, sulfur or oxygen 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 different shapes. They may be (a) fused benzene structures, (b) fused ring structures in which no ring or not all rings are benzene, (c) linked rings, (d) hetero-15 cyclic compounds, (e) non-aromatic or partially saturated ring systems or (f) three-dimensional structures.

Fused benzene structures from which the compounds may be derived are 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, compounds in which rings are coupled together include diphenyl. Suitable heterocyclic compounds from which they may be derived are, for example, quinoline, pyrindine, indole, 2: 3 dihydroindole, benzofuran, coumarin, isocarin, benzothiophene, carbazole and thiodiphenylamine. Suitable non-aromatic or partially saturated ring systems are, for example. decalien (decahydronaphthalene), o-pinene, cadinene, bornylene. Suitable three-dimensional compounds are, for example, norbornene, bicycloheptane (norbornane), bicyclooctane and bicyclooctene.

The two substituents X and Y must be attached to adjacent ring atoms in the ring when there is only one ring, or adjacent ring atoms in one of the rings when the compound is polycyclic, in the latter case this means that if naphthalene is used, these substituents cannot be attached to the 1,8 or 4,5 positions, but must be attached to the 1,2-, 2,3-, 3,4-, 5,6-, 6.7 or 7.8 positions.

V. 172 05 1 1 8

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 with a hydrogen and 5 carbon-containing group or groups containing at least 10 and 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 containing at least 10 carbon atoms or with a mixture of an alcohol and an amine. r

The hydrogen and carbon-containing groups in the substituents are preferably hydrocarbon groups, although also halogenated hydrocarbon groups can be used, which preferably contain only a small amount of halogen atoms (e.g. chlorine atoms), e.g. 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 they are not preferred.

The alkyl groups preferably contain at least 10 carbon atoms, preferably 12-22 carbon atoms, e.g. 14-20 carbon atoms, and are preferably linear or branched at the 1- or 2-25 positions. If branching is present in more than 20% of the alkyl chain, 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). Suitable alkylene groups are hexylene, octylene, dodecylene and hexadecylene, but these are not preferred.

In the preferred embodiment, wherein the intermediate is reacted with the secondary amine, one of the substituents will preferably be an amide and the other will be an amine or dialkyl ammonium salt of the secondary amine. The particularly preferred additives are the amides and amine salts of secondary amines.

In order to obtain the fuels according to the invention, these additives are generally used in combination with other additives, and examples of the other additives are such, 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 '

G = H, Or D

10 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', CO2 H L = H, R ', CO.OR', OCO.R ', aryl, CO2 H n = 0.0 to 0.6 (molar ratio)

15 R <c1Q

E '<Cj

If necessary, another monomer may be terpolymerized.

If these other additives are copolymers of olefins-1 and maleic anhydride, they can be conveniently prepared by polymerizing the monomers without a solvent or in a solution in a hydrocarbon solvent, such as heptane, benzene, cyclohexene or white oil, at a temperature which generally in the range of 20-150 ° C, and usually with a peroxide or an azo-type catalyst promoter, such as benzoyl peroxide or azo-diisobutyronitrile, covered with an inert gas, such as nitrogen or carbon dioxide, in order to exclude oxygen. Preferably, but not necessarily, equimolecular amounts of the olefin and maleic anhydride are used, although mole ratios in the range of 2: 1 and 1: 2 are also suitable. Examples of olefins which can be copolymerized with maleic anhydride are decene-1, dodecene-1, tetradecene-1, hexadecene-1, octodecene-1.

The copolymer of the olefin and maleic anhydride can be esterified by any suitable technique and preferably, but not necessarily, the maleic anhydride is at least 50% esterified. Examples of alcohols that can be used are; 172 65 1 1 10 n-decanol-1, n-dodecanol-1, n-tetradecanol-1, n-hexadecanol-1, n-octa-decanol-1. The alcohols may also contain at most one methyl branch per chain, for example 1-methylpentadecanol-1,2-methyltridecanol-1-1. The alcohol can be a mixture of normal and straight methyl 5-branched alcohols. Any alcohol can be used for the esterification of copolymers of maleic acid with one of the olefins. Preferably pure alcohols are used and not the commercially available alcohol mixtures, but mixtures are used, then R refers to the average number of carbon atoms in the alkyl group; if 10 alcohols are used which contain a branch in the 1 or 2 position, R refers to the linear backbone segment of the alcohol. When mixtures are used it is important that not more than 1% of the groups R have a value of R + 2. The choice of alcohol will of course depend on the olefin copolymerized with maleic anhydride, such that R + R has a value "from 18 to 38. The preferred value of R + R * may depend on the cooking properties of the fuel in which the additive is to be used.

The comb polymers can also be fumarate polymers and copolymers, as described in European patent applications 0153176, 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 which can be used together with the cyclic compound are the polyoxyalkylene esters, ethers, ester / ethers and mixtures thereof, in particular containing at least one, preferably at least two C 1 -C 2 -C linear saturated alkyl groups and a polyoxyalkylene glycol group with a molecular weight of 100-5000, preferably 200-5000, wherein the alkyl-30 group in the polyoxyalkylene glycol contains 1-4 carbon atoms. These materials are the subject of EU patent 61,895 B. Other such additives are described in US patent 4,491,455.

The preferred esters, ethers or ester / ethers which are suitable according to the invention can be structurally represented by the formula R - 0 (A) - O - R '', 872. §5 11 11 R and R "are the same or different and represent n-alkyl or a group of formula 5, 6 or 7, wherein the 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 atoms, such as polyoxymethylene, polyoxyethylene or polyoxytrimethylene molecular moiety, which is substantially linear; some degree of branching with lower alkyl side chains (such as in polyoxypropylene glycol) may be allowed, but preferably the glycol is substantially linear; A can also contain nitrogen.

Suitable glycols are generally the substantially linear polyethylene glycols (PEG) and polypropylene glycols (PPG) with a molecular weight of 100-5000, preferably 200-2000. Esters are preferred and fatty acids with 10-30 carbon atoms are suitable for reaction with the glycols to form the ester additives, preferably using a C 1 -G-C 24 fatty acid, especially behenic acids. The esters can also be prepared by esterification of polyethoxylated fatty acids or polyethoxylated alcohols.

Polyoxyalkylene diesters, diethers, ether / esters, and mixtures thereof are suitable as additives, with diesters being preferred for use in narrow boiling distillates, while minor amounts of monoethers and monoesters may also be present and often formed during the manufacturing process. It is important for the behavior of the additive that a major amount of the dialkyl compound is present. In particular, steric or behenic acid diesters of polyethylene glycol, polypropylene glycol or mixtures of polyethylene and polypropylene glycol are preferred.

The additives to be used may also contain copolymers of ethylene and unsaturated esters as flow improvers. 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 an -OOCRg group, wherein Rg is hydrogen or a C18 -C28 'residential. * - ^ · ^ ci-ci7 and preferably represents a crc8 linear or branched alkyl group, or wherein Rg is a -COORg group, wherein R0 has the aforementioned meaning, but no water-

O

35 represents substance, and R 1 represents hydrogen or -COORg, as previously defined. When Rg and hydrogen represent and Rg is -OOCRg, '872 05 1 1 12 the monomer comprises vinyl alcohol esters of usually C 1 -C 20 g monocarboxylic acid and preferably C 2 -C 29 9 residential C 1 -C 18 monocarboxylic acid and preferably C 2 CS Monocarboxylic Acid Examples of vinyl esters that can be copolymerized with ethylene include vinyl acetate, vinyl propionate, and vinyl butyrate or isobutyrate, of which vinyl acetate is preferred. When used, the copolymers preferably contain 5-40% by weight of the vinyl ester, especially 10-35% by weight of vinyl ester. They can 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.

The additives used may also contain other polar compounds, both ionic and nonionic, which have the ability to function in fuels as wax crystal growth inhibitors. Polar nitrogen-containing compounds have proven particularly effective 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 molar amount of hydrocarbyl-substituted amines with a molar amount of hydrocarbic acid having 1-4 carboxylic acid groups or their anhydrides; ester / amides can also be used, which contain a total of from 30 to 300, preferably from 50 to 150, carbon atoms. These nitrogen compounds are described in U.S. Patent 4,211,534. Suitable amines are usually primary, secondary, tertiary or quaternary long chain amines or mixtures thereof, although shorter chain amines may also be used, provided that the resulting nitrogen compound is oil soluble and therefore usually about 30-300 in total. contains carbon atoms. The nitrogen compound preferably contains at least one C3-C24 linear-chain alkyl segment.

Suitable amines are primary, secondary, tertiary or quaternary, but are preferably secondary. Tertiary and quaternary amines can only form amine salts. Examples of amines are tetradecylamine, cocoamine, hydrogenated tallowamine and the like. Examples of secondary amines are dioctadecylamine, methyl behenyl-35 amine and the like. Mixtures of amines can also be used, and many amines derived from natural materials are mixtures.

.8J205 1 1 13

The preferred amine is a secondary hydrogenated talloamine of the formula HNR ^ ^, wherein R ^ and R2 are alkyl groups derived from hydrogenated tallo fat composed of about 4% C ^, 31% C ^ g and 59% c10.

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, naphthalene dicarboxylic acid and the like. Generally, these acids contain about 5-13 carbon atoms in the cyclic molecular moiety. Preferred acids useful 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 particularly preferred compound is the amide amine salt formed by. reaction of 1 mol of phthalic anhydride with 2 molds of dihydro-generated talloamine. Another preferred compound is the di-amide formed by dehydration of this amide-amine salt.

Hydrocarbon polymers can also be used as part of the additive combination to form the fuels of the invention. They can be represented by the general formula 9, wherein T = H or R ', U = Η, T or aryl, v = 1.0 - 0.0 (molar ratio), w = 0.0 - 1, 0 (molar ratio) and R represents a normal alkyl group with more than 10 carbon atoms.

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 on it with an ethylene content of preferably 50-60% (w / w).

The amount of additive required to prepare the distillate fuel oil of the invention will vary depending on the fuel, but is generally 0.001 -0.5 wt%, eg 0.01-0.1 wt .% (active substance), calculated on the weight of the fuel. The additive may conveniently be dissolved in a suitable solvent to a concentrate of 20-90% by weight, for example 30-80% by weight in the solvent. Suitable solvents. 1720511 14 are kerosene, aromatic naphthas, mineral lubricating oils, etc.

The invention is illustrated by the following examples, in which the size of the wax crystals in the fuel was measured by placing fuel samples in bottles of about 60 cm3 in coolers, in which they were placed at about 8 ° C above the 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 1 ° C / hr and held there.

10 A prefabricated filter support, consisting of a sintered ring with a diameter of 10 mm, surrounded by a 1 mm wide annular metal ring, which carries a 200 nanometer classified silver membrane filter, which is placed in place by two vertical pins is then placed on a vacuum unit. A vacuum of at least 80 kPa is drawn and the cooled fuel is dripped onto the membrane from a clean dropper pipette until a small convex puddle just covers the membrane. The fuel is dripped slowly to maintain the pool; After about 10-20 drops of fuel have been added, the puddle is allowed to drain through the filter, leaving a thin, dull layer of fuel-wetted wash cake on the membrane. A thick layer of wax is not acceptable to wash, and a thin layer can be washed away. The optimal layer thickness is a function of the crystal shape, 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 excessive fuel residue and crystal "lubrication" and should be carted.

The cake is then washed with a few drops of methyl ethyl ketone, which can drain completely. This process is repeated several times. When the washing is complete, the methyl ethyl ketone will disappear very quickly, leaving a "glossy dull 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 kept there until ready for coating in the SEMo. It may be necessary to cool the sample in order to preserve the wax, in which case the sample must be stored in a cool box r, § J 2 8 & 1 i 4 15 before transferring (in a suitable sample transport vessel) to the SEM to avoid ice crystal formation on the surface of the sample.

During the coating, the sample should be kept as cold as possible to minimize damage to the crystals. Electrical contact with the "stage" is best provided by a locking screw, which presses the annular ring against the side of a well in the "stage", such that the sample surface can lie on the image plane of the instrument . Electrically conductive paint can also be used.

Once coated, the micrographs are conventionally obtained on the Scanning Electron Microscope (SEM). The photo-micrographs are analyzed to determine the mean particle size by attachment to a suitable micrograph of a transparent sheet, with 88 dots (as dots) applied to the intersections of a regular grid, which are 8 rows and Contains 11 equidistant columns. The magnification should be such that only some of the largest crystals are hit by more than one dot; a magnification of 4000-800 times has been found suitable. At each grid point 20, if the dot contacts a crystal size, the shape of which can be clearly defined, the crystal can be measured. Also, "scattering" is measured in the form of the Gaussian standard deviation of the crystal length with Bessel correction.

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

The DSC is calibrated using an additive, which forms large crystals, which are certainly removed through the filter, this calibration fuel being fed into the set-up at the test temperature and the WHAT of the thus dewaxed fuel is measured on the DSC. The samples of tank fuel and fuel to be tested after the filter are then analyzed on the DSC and for each fuel, the area above the baseline becomes WAT of the cal. 872 65 1 1 16 brering fuel determined. The ratio DSC area for the sample after the filter / DSC area for the tank sample x 100% is the percentage of wax remaining after the filter.

The cloud point of distillate fuels was determined according to the standard Cloud Point Test (IP-219 or ASTM-D 2500); other measurements of the crystallization onset are the Wax Appearance Point (WAP) Test (ASTM D.3117-72) and the Wax Appearance Temperature (WAT), which are measured by DSC using a Mettler TA 2000B Differential Scanning calorimeter.

The ability of the fuel to pass through the main filter of a diesel vehicle was determined in an equipment consisting of a typical main filter of a diesel vehicle mounted in a standard housing in a fuel line; the Bosch type, such as. used in a 1980 Volkswagen Golf diesel passenger car and a 15 Cummins FF105 as used in the Cummins NTC engine range are suitable. A reservoir and a supply system, capable of supplying half the fuel in a normal fuel tank, connected to a fuel injection pump, as used in the Volkswagen Golf, are used to pump fuel at a constant flow rate through the filter 20 from the tank , 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. Bins are provided for collecting the pumped fuel, both "injected" fuel and the excess fuel. 25 Before the test, the tank is filled with 19 kg of fuel and tested for leaks. If satisfactory, the temperature is stabilized at an air temperature 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 30 hours to stabilize the temperature of the fuel. The tank is shaken vigorously to completely disperse the wax present; A sample is taken from the tank and 1 1 of fuel is removed through a sampling point in the drain line immediately behind the tank and then returned to the tank. The pump 35 is started and the speed of the pump is set at the speed at a road speed of 110 km / h. For a Volkswagen * £ 7 2 C 5 11 17

Wave 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, typically 30-35 min.

5 If the fuel supply to the injector can be kept at 2 ml / sec (the excess fuel will be approximately 6.5-7 ml / sec), the result is "successful". A drop in fuel supply to the injectors indicates a "limit case"; zero flow means "failed".

A "successful" result can typically be accompanied by an increasing pressure drop across the filter, which may rise up to 60 kPa. In general, significant amounts must be passed through the filter to achieve such a result. "Successful" is a test where the pressure drop across the filter does not rise above 15 kPa and is the first indication that the majority of the laundry has passed through the filter; an excellent result has a pressure drop of less than 5 kPa.

Furthermore, fuel samples were taken from the "excess" fuel and the "injector feed" fuel, ideally 20 every 4 min throughout the test. These samples together with the pre-test tank samples are compared by DSC to determine the amount of feed wax passed through the filter. Fuel samples are also taken before the test and SEM samples are prepared therefrom to compare the wax crystal size and type with the actual behavior.

The following additives were used:

Additive 1

This is the Ν, Ν-dialkylamonium salt of 2-dialkylamido-benzenesulfonate, in which the alkyl groups are prepared by reacting 1 mole of ortho-sulfobenzoic acid cyclic anhydride with 2 moles of di- (hydrogenated) tallo- amine 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.

Analysis of the product by NMR spectroscopy (500 MHz). 872 05 1 1 18 confirmed the structure as that of formula 10.

Additive 2

This is a copolymer of ethylene and vinyl acetate with a vinyl acetate content of 17% by weight, a molecular weight of 3500 and a degree of side chain branching of 8 methyl groups per 100 methylene groups, measured by NMR '(500 MHz).

Additive 3

This is a styrene-dialkyl maleate copolymer prepared by esterification of a 1: 1 molar styrene-maleic anhydride co-10 polymer with 2 moles of a 1: 1 molar mixture of C 2 H 25 ° H and C 14 H 290 H per mole of anhydride groups used at the esterification (small excess, 5% alcohol used) using p-toluenesulfonic acid as a catalyst (1/10 mol) in xylene solvent, giving a number average. yielded a molecular weight of 50,000 and a product containing 3% (w / 15 wt) unreacted alcohol.

Additive 4

Dialkyl ammonium salts of 2-N, N-dialkylamido benzoate formed by mixing 1 mole part phthalic anhydride with 2 mole parts dihydrogenated talloamine at 60 ° C.

20 The results were as follows.

Example 1

Fuel properties

Cloud point -14 ° C

WHAT -18.6 ° C

^ Initial boiling point 178 ° C

20% 230 ° C

90% 318 ° C

Final boiling point 355 ° C

Wax content at -25 ° C 1.1 wt.% 30

Of each of the additives 1, 2 and 3, 250 parts per million was included in the fuel; the test temperature was -25 ° C.

The wax crystal size was found to be 1200 nanometers (length) and more than 90% by weight of the wax passed through the Cummins FF105 filter.

The passage of wax was further found upon observation during the test of the pressure drop across the filter, which increased only by 2.2 kPa.

<·. I? I 0511 19

Example 2 - Example 1 was repeated, the wax crystal size being 1300 nanometers and the maximum final pressure drop across the filter 3.4 kPa.

5 Example 3

Brands cool, by the way

Cloud point 0 ° C

WHAT -2.5 ° C

Initial boiling point 182 ° C

10 20% 220 ° C

90% -354 ° C

Final boiling point 385 ° C

Wax content at the test temperature 1.6% by weight

250 parts per 15 million of each of additives 1, 2 and 3 were used; the wax crystal size was found to be 1500 nanometers and about 75% by weight of the wax was 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, the wax crystal size being 2000 nanometers (length), of which about 50% by weight was passed through the filter, resulting in a maximum pressure drop of 35.3 kPa.

Example 5 The fuel used in Example 3 was treated with 400 ppm of 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 wt% . The wax crystal size was found to be 2500 nanometers and 50% of the wax was passed through the filter, resulting in a maximum final pressure drop of 67.1 kPa.

Comparative example 6

The fuel used in Example 3 was treated with 500 parts per million of a mixture of 4 parts Additive 4 and 1 part Additive 2 and tested at -80 ° C; the wax crystal size was found to be 6300 nanometers and 13% by weight of the wax was passed through the filter. This example is one of the very best in the prior art .8710511 20 technique, with no crystal passage at all.

Figures 1-6 show "scanning electron micrograph" of the wax crystals that form in the fuel of Examples 1-6.

Examples 1-4 show that crystals can be reliably passed through the filter and that the excellent low temperature behavior can be extended to fuels with higher wash contents than previously possible and also at temperatures further below the WAT of the fuel than was previously possible. This applies regardless of fuel system considerations, such as the ability to recycle fuel from the engine to heat the fuel supply pumped from the fuel tank, the ratio of fuel flow to the recycle fuel, the ratio of the surface area of the fuel the main-15 filter to the fuel supply flow and the location and size of pre-filters and screen meshes.

Examples 1-3 show that for the tested filters, crystal lengths of less than about 1800 nanometers result in dramatically better fuel behavior.

20 Example 7

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

Initial boiling point 180 ° C

20%, 223 ° C

90% 336 ° C

Final boiling point 365 ° C

WHAT -5.5 ° C

Cloud point -3.5 ° C

For comparison purposes, the following additive was also added to the distillate fuel:

Additive A:

A mixture of ethylene / vinyl acetate copolymers, one consisting of additive 2 (1 part by weight) and the other (3 parts by weight) having a vinyl acetate content of 36% by weight, a number average molecular weight of 2000 and a degree of side chain branching between 2 and 3 methyl groups per 100 methylene groups, measured by NMR at 500 MHz.

.872 05 1 1 21

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

Additive C: 5 The dibehenate of a polyethylene glycol mixture having an average molecular weight of 600.

Additive D:

An ethylene / propylene copolymer with an ethylene content of 56% by weight and a number average molecular weight of about 60,000.

The additives were added in the amounts as indicated in the table below and tests were carried out according to the PCT, the details of which are as follows: "Programmed Cooling Test" (PCT) τ

This is a slow cooling test intended to relate to the pumping of a stored heating oil. The cold flow properties of the fuel containing the additives are determined according to the PCT as follows. 300 ml of fuel is cooled linearly at a rate of 1 ° c / hour to the test temperature, after which the temperature is kept constant. After staying at the test temperature for 2 hours, about 20 ml of the surface layer is removed by suction to prevent the test from being affected by the abnormally large wax crystals which may form at the oil / air interface during cooling. Wax that has settled in the bottle is dispersed by gentle stirring, after which a CFPPT filter assembly is fired. The tap is opened to apply a vacuum of 500 mm mercury pressure and is closed when 200 ml of fuel has passed through the filter in the graduated collecting vessel: the result is "successful" if the 200 ml is within 10 sec. has been collected by a given screen size, or "failed" if the flow rate is too slow, indicating that the filter has become blocked.

The sieve size that has passed at the test temperature is noted.

(1) CFPPT - "Cold Filter Plugging Point Test" (CFPPT), detailed in "Journal of the Institute of Petroleum", 35 52 (No. 510), July 1966, 173-185.

c i Ί 2 δ 5 1 1 22

TABLE

Additive Finest sieve mesh (mm), passed at (mol ratio) -11 ° C _______ 150 ppm 250 ppm (active ingredient 5 A 0.150 0.074 4 0.250 0.125 1 0.074 0.040 4/2 (4/1) 0.150 0.040 1/2 (4 / 1) 0.040 0.040 10 4 / C (9/1) 0.100 0.060 1 / C (9/1) 0.060 0.040 r 4 / D (9/1) 0.100 0.040 1 / D (9/1) 0.040 0.040

It appears that when only one additive is added, the best results are achieved with additive 1, and that when additive pairs are used, the best results are achieved if additive 1 is part of the pair.

Example 8

The fuel used in this example had the following 20 properties: (ASTM-D86)

Initial boiling point 190 ° C

20% 246 ° C

90% 346 ° C

25 Final boiling point 374 ° C

WHAT -1.5 ° C

Cloud point + 2.0 ° c

The fuel was treated with 1000 parts per million active ingredient of the following additives: 30 (E) A mixture of additive 2 (1 part by weight) and additive 4 (9 parts by weight).

(F) The commercially available ethylene / vinyl acetate, 1/15511 23 copolymer additive, marketed by Exxon Chemicals as ECA 5920.

(G) A mixture of: 1 part additive 1 5 1 part additive 3

1 part additive D 1 part additive K.

(H) The commercially available ethylene / vinyl acetate copolymer additive, marketed 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 without solvent at 150 ° C for 15 hours under nitrogen.

The following behavioral properties of these fuels were measured.

(i) The fuel's ability to pass the main-20 filter for the diesel fuel at -9 ° C and was the percentage that is passed through the filter, obtaining the following results:

Additive Time to failure% passed was E 11 min 18 - 30% 25 F 16 min 30% G no failure 90 - 100% H 15 min 25% I 12 min 25% J 9 min 10% 30 (ii) The pressure drop across the main filter against time; the results are shown graphically in Fig. 7.

(iii) The settling wax was measured by cooling fuel in a 100 ml graduated cylinder, which top level corresponds to 100% of the height of the fuel. Cylinder 35 is heated at a rate of 1 ° C / hour from a temperature which is preferably 10 ° C above the cloud point of the fuel but not less than 5 ° C above the cloud point of the fuel. fuel is located, cooled to the test temperature, which is then maintained for a prescribed time. The test temperature and the residence time depend on the application, i.e. diesel fuel and heating oil. The test temperature is generally at least 5 ° C below the cloud point and the minimum cold 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.

After the end of the residence period, the graduated cylinder is inspected and the degree of wax crystal settling is measured visually as the height of the wax layer above the bottom of the cylinder (0 ml), r 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 on the settling wax. Often the fuel above a settled wax crystal layer is cloudy or it can be seen that the wax crystals are visibly denser the closer they are to the bottom of the cylinder. In that case, a more quantitative analysis method is applied. Hereby the top 5% (5 ml (fuel is carefully aspirated and stored, the next 45% is aspirated and carted, the next 5% is aspirated and stored, the next 35% is aspirated and carted and finally the bottom 10% after heating for solution of the wax crystals collected The stored samples are further referred to as the top, middle and bottom samples It is important that the applied vacuum is relatively low, in particular 200 mm water pressure, and that the top of the pipette is placed just on the surface of the fuel to prevent flow in the liquid, which could interfere with the wax concentration at various locations within the cylinder, the samples are then heated to 60 ° C for 15 min and examined by Differential Scanning Calorimetry ( DSC), as described elsewhere in this text.

The DSC technique involves the use of a device, such as the Dupont 9900 series or the Mettler TA 2000b. In this case, the latter device was used. A 25 microliter sample is placed in the sample cell, while regular kerosene is placed in the reference cell, after which both 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 WAT. A reference test must be conducted with the unblanked, uncooled treated fuel. The degree of settling is then related to the WHAT (or WHAT = WHAT settled sample-WHAT originally). 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 settling from these samples. This is shown by% Was (% Was =%

Waxed sample -% Wash originally) and again negative values indicate fuel dewaxing and positive values indicate wax enrichment during settling. These wash levels are obtained by measuring the area under the DSC curve to a specified temperature.

The fuel wax was cooled from + 10 ° C to -9 ° C at a rate of 1 ° C / hour and then stored cold for 48 hours before testing. The results were as follows: 20

Additive Visual observation WHAT ° C data settling Upper Middle Lower _ 5% 5% 10% E completely cloudy -10.80 -4.00 -3.15 closer to the bottom 25 F 50% clear -13.35 -0.80 -0.40 above G 100% -7.85 -7.40 -7.50 H 35% clear -13.05 -8.50 +0.50 above 30 I 65% clear above J 100% semi-gel - 6.20 -6.25 -6.40 (The results are also shown graphically in Fig. 8).

c 8 7 2 0 5 1 1> 26 WHAT originally WHAT (° C) (settled samples) ((uncontaminated fuel) Upper 5% Middle Lower _ _ 5% 10% E -6.00 -4.80 +2.00 +2.85 5 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 (It can be seen that a significant reduction of the 10 WAT can be achieved by the most effective additive (G)).

% Wax (settled samples)

Top 5% Middle 5% Bottom 10% E -0.7 +0.8 +0.9 F -0.8 +2.1 +2.2 15 H -1.3 -0.2 +1.1 G ± 0.0 +0.3 +0.1 J -0.1 ± 0.0 ± 0.1 (% Wax is measured by extending the original baseline and measuring the surface area of the WAT to 20 in this case - 25 ° C. Calibration has previously been carried out on a known amount of crystallizing wax).

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 points exhibit little wax crystal utilization because the plate-like crystals interlock and cannot tumble freely in the liquid to form 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 more needle-like with dimensions in the range of tenths of micrometers, which needles can move freely in the liquid and settle relatively quickly. This settling of wax crystals can cause problems in storage tanks and vehicle systems. Concentrated wax layers can be pumped unexpectedly, especially when the fuel level is low or the tank is disturbed (for example, when a vehicle is turning a corner), which can cause blockage of the oIJ2 05 11 27 filter.

If the wax crystal size can be further reduced to below 10,000 nanometers, the crystals will settle relatively slowly and anti-wax settling may result, resulting in fuel behavior advantages over a fuel with settled wax crystals. If the wax crystal size can be reduced below about 4000 nanometers, the tendency of the crystals to settle is eliminated almost for the duration of the fuel storage. If the crystal sizes are optimally reduced, the wax crystals remain suspended in the fuel for the many weeks required in some storage systems, and the problems are effectively eliminated.

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

Additive CFPP Temperature CFPP Decrease 15 E -14 11 F -20 17 G -20 17 H -20 17 I -19 16 20 J -3 (v) The mean crystal size was determined as follows:

Additive Dimensions (nm) E 4400 25 F 10400 G 2600 H 10800 I 8400 J thin plates approx. 50,000 e 872 05 1 1

Claims (5)

1. Distillate fuel oil, boiling in the range of 120-500 ° C, with a wax content of at least 0.3 wt% at a temperature 10 ° C below the Wax Appearance Temperature, which wax crystals have an average particle size at that temperature 5 of less than 4000 nanometers. The distillate fuel of claim 1, wherein the wax crystals have an average particle size of less than 3000 nanometers. Distillate fuel according to claim 1, wherein the wax-10 crystals have an average size of less than 2000 nanometers The distillate fuel of claim 1, wherein the wax crystals have an average particle size of less than 1500 nanometers. Distillate fuel according to claim 1, wherein the wax-15 crystals have an average particle size of less than 1000 nanometers. , 172051!