FI90349B - An intermediate distillate composition with reduced wax crystal size - 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

90349 The present invention relates to an improved fuel oil distillate.

Mineral oils containing paraffin waxes, such as distilled fuels used as diesel and fuel oil, are characterized by becoming less fluid as the temperature decreases. This decrease in fluidity is due to the crystallization of the wax into plate-like crystals, possibly forming a porous, oil-enclosing mass, and the temperature at which the wax crystals begin to form is known as the cloud point, and the temperature at which the wax prevents oil pour is known as the solidification point.

It has long been known that various additives act as freezing point depressants when mixed with waxy mineral oils. These compounds alter the size and shape of the wax crystals and reduce the cohesive forces between the crystals and the wax and oil so as to allow the oil to remain liquid at lower temperatures and to remain pourable and capable of passing through coarse filters.

Various pour point depressants have been described in the literature, and many of them are in commercial use. For example, U.S. Patent 3,048,479 teaches the use of copolymers of ethylene and C 1 -C 4 vinyl esters, e.g., vinyl acetate, as a pour point depressant in fuels, particularly heating, diesel, and jet fuel fuels. Polymeric pour point depressants based on ethylene and alpha-olefins, e.g. polypropylene, are also known. us - Patent 3,252,771 relates to the use of C16-C18 polymers of alpha-olefins in combination with aluminum trichloride / alkyl halides in the context of distilled "wide boiling point" "easy to handle" fuels available in the United States in the early 1960's.

2,90349 In the late 1960s and early 1970s, great emphasis was placed on improving the filterability between the cloud point and the pour point of oils, as determined by the rather rigorous "Cold Filter Plugging Point" (CFPP) test (IP 309/80), Since then, several patents have been published relating to the improvement of fuel properties in this experiment. U.S. Patent 3,961,916 teaches the use of a copolymer blend to control the size of wax crystals. GB Patent 1,263,152 proposes that the size of wax crystals be adjusted by using a copolymer with a smaller number of side branches in the chain.

For example, GB Patent 1,469,016 also proposes that copolymers of di-n-alkyl fumarates and vinyl acetate, previously used as pour point depressants for lubricating oils, be used as separate additives temperatures.

It has also been proposed to use additives based on olefin / maleic anhydride copolymers. For example, U.S. Pat. No. 2,542,542 uses copolymers of olefins such as octadecene with maleic anhydride esterified with an alcohol such as lauryl alcohol as pour point depressants, and GB Patent 1,468,588 uses copolymers of α-C20 olefins with O as separate additives for fuels distilled with behenyl alcohol. Consistent with this, copolymers of olefin / maleic anhydride which have reacted with an amine are used as pour point depressants in JA Patent No. 5,654,037.

JA Patent No. 5,654,038 uses derivatives of olefin / maleic anhydride copolymers in combination with conventional intermediate flow improvers such as ethylene-vinyl acetate copolymers. JA Patent No. 5,540,640 discloses the use of olefin / maleic anhydride copolymers (non-esterified towers) and states that the olefins used should contain more than 20 carbon atoms to achieve a CFPP effect. GB Patent 2,192,012 uses blends of certain esterified olefin / maleic anhydride copolymers and low molecular weight polyethylene, the esterified copolymers being ineffective when used alone.

The improvement in CFPP efficiency by the addition of the additives of these patents has been achieved by altering the size and shape of the wax crystals and causing them to form mostly needle-like crystals, generally 10,000 nanometers or larger, typically 30,000 to 100,000 nanometers. When diesel engines are used at low temperatures, these crystals do not pass through the engine's paper fuel filter, but form a filter-permeable cake that passes through the fuel, the wax crystals dissolving later as the engine and fuel warm up, which can occur with fuel heating in the fuel tank. However, the formation of wax can clog the filters, leading to difficulty starting the diesel engine and problems in cold weather at the start of driving, as well as disrupting the operation of oil-heating systems.

It has now surprisingly been found that waxy fuels with a wax crystal size small enough to pass through the low temperature paper main filters typically used in diesel engines can be obtained by the addition of certain additives.

Therefore, the present invention provides fuel oils boiling in the temperature range of 120 to 500 ° C, having a wax content of at least 0.3% by weight at a temperature below 10 ° C of the onset of wax, and having an average particle size of the wax crystals at this temperature of less than 4000 nmol. meters.

4,90349

The Wax Appearance Temperature (WAT) in the fuel is measured with a differential scanning calorimeter (DSC). In this experiment, a small sample of fuel (25 microliters) is cooled at 2 ° C / minute together with a reference sample having the same heat storage capacity but which does not precipitate as a wax in the temperature range in question (such as kerosene). When crystallization begins, an exothermic reaction is observed in the sample. For example, the WAT of the fuel can be measured by extrapolating the Metier TA 2000B with a differential scanning calorimeter11a.

The wax content of the fuel is derived from the DSC curve by integrating the area bounded by the baseline and the exothermic peak to the specified temperature. Calibration has been performed with a previously known amount of crystallizing wax.

The average particle size of the wax crystals is measured by analyzing the scanning image of the fuel sample from an electron microscope over a range of 4000-8000x magnification and measuring the maximum dimension from at least 40 points out of 88 in a predetermined frame. It has now been found that by making the average particle size smaller than 4000 nanometers, the wax begins to pass through the typical paper filters used in diesel engines, although a size of 3000 nanometers, preferably less than 2000, even more preferably less than 1500 nanometers, and most preferably less than 1000 nanometers is now preferred. the real benefits of passing through a paper filter. The actual size to be achieved depends on the original nature of the fuel and the amount and nature of the additives used, but it has now been found that such and smaller sizes are achievable.

The ability to produce such small wax crystals in the fuel results in significant benefits in the usability of the diesel engine.

This can be demonstrated by pumping the blended fuel through a diesel filter paper used in V.W. In golf or Cummins diesel engines at 8 to 15 ml / s and 1,0 to 2,4 liters per minute per square meter of filter surface at a temperature of at least 5 ° C below the wax onset temperature with a fuel with a solid the wax content is at least 0.5% by weight. Both wax and fuel are considered to have passed the filter successfully if one or more of the following criteria are met.

(i) After 18 to 20 liters of fuel have passed through the filter, the pressure drop across the entire surface of the filter shall not exceed 50 kiloPascall (kPa), preferably 25 kPa, more preferably 10 kPa and most preferably 5 kPa.

(ii) Not less than 60%, preferably at least 80% and even more preferably 90% of the wax in the original fuel, as determined by the DSC test described previously, is present in the fuel leaving the filter.

(iii) When pumping 18-20 liters of fuel through the filter, the flow rate will always remain greater than 60% of the original flow rate, and preferably 80% of the original.

The number of crystals passing through the motor filter and the usability benefit of small crystals depend greatly on the length of the crystals, although the shape of the crystals is also essential.

It was now found that cube-shaped crystals have a slightly better tendency to pass through filters than is characteristic of flat crystals, and have a lesser effect on increasing fuel flow resistance when they do not pass through the filter. However, the primary crystal form is flat, which in principle allows a larger amount of wax to precipitate as the temperature decreases, and therefore a larger amount of wax precipitates before the critical crystal length is reached than would be the case with cubic crystals of the same length.

The fuels of the present invention have striking advantages over formerly distilled fuels whose cold flow properties have been improved with conventional additives. These fuels also have improved cold start properties at 6,90349 low temperatures that do not depend on thermal fuel recirculation to remove unwanted wax deposits. Furthermore, wax crystals tend to remain in suspension rather than settle to the bottom of the container and form wax layers, as is the case when treating fuels with conventional additives to aid in their distribution.

In addition, these fuels generally have better performance in the cold climate body dynamometer test compared to fuels containing conventional additives. In many cases, these fuels also have improved CFPP properties.

Normal quality distilled fuels boiling in the range of 120-500 ° C vary widely in their boiling properties, n-alkane distribution and wax content. Northern European fuels generally have lower final boiling points and cloud points than their corresponding southern Europeans. The wax content is usually higher than 1.5% (10 ° C below WAT). Similarly, fuels around the world vary from country to country according to similar climatic conditions, but the wax content also depends on the source of the crude oil. Fuels shipped from the Middle East are likely to have lower wax content than waxy Chinese or Australian crude oils.

The size to which very small crystals can be obtained depends on the nature of the fuel itself, and for some fuels it may be impossible to obtain the extremely small crystals of this invention.

However, if such a problem occurs, the properties of the fuel can be altered by making it possible to obtain such small crystals, for example by changing the conditions and mixing of the refinery, and thus enabling the use of suitable additives.

The general formula of the additives we prefer is A X - R1 ^ C 1

C

B 1 - R 2 7 90349 where -Y-R 2 is SO 3 ("] (+} NR 2 R 2, -SO 3 (') (+} BNR 3 R 2, -so 3 (_) (+) h 2nr 3r 2, -so3 (-) U) h 3nr 2, -SO2NR3R2 or -SO3R2; -X-R1 is -Y-R2 or -CONR3R1, -co2 <-) (+) nr3r1, -co2 (_) (+) hnr | r1, -CO2 (_) (+) H2NR3R1 , -CO2 (-) (+) h3nr1, -R4-COOR1 (-nr3cor1, 4 1 4 1 4 1 R4OR, -R OCOR1, -R * R, -N (COR3) R1 or Z (_) ^ NR ^ R 1; -Z 1 - is SO 3 (*) or -CO 2 (-); R 1 and R 2 are alkyl, alkoxyalkyl or polyalkoxyalkyl having at least 10 carbon atoms in the main chain; R 3 is hydrocarbyl, and each R 3 may be the same or

different, and R is zero or C 1 -C 4 alkylene, and in formula A

C

c the carbon-carbon bond (CC) is either a) ethylenically unsaturated when A and B may be alkyl, alkenyl or substituted hydrocarbyl groups, or b) part of a cyclic structure which may be aromatic, polynuclear aromatic, or cyclo-1 aliphatic, is it is preferred that XR and YR between them contain at least three alkyl, alkoxyalkyl or poly-α1 coke allyl groups.

The ring atoms of such a cyclic compound are primarily carbon atoms, but may nevertheless contain an N, S or O ring atom to give the heterocyclic compound.

8 90349

Examples of aromatic-based compounds from which additives can be prepared include those in which the aromatic group may be substituted.

Alternatively, they can be obtained from polycyclic compounds, i. those with two or more ring structures that can take different shapes. They may be a) compacted benthic fungal structures, b) sealed ring structures in which none or all of the rings are benzene, c) end-to-end rings, d) non-aromatic or partially saturated ring systems, or f) three-dimensional structures.

Concentrated benzene structures from which compounds can be derived include, for example, naphthalene, anthracine, phenatrin, and pyridine.

Condensed structures in which none or all of the rings are benzene include, for example, azulene, indene, hydroindenifluorene, diphenylene. Compounds in which the rings are attached at their ends include, for example, diphenyl. Suitable heterocyclic compounds from which they may be derived include quinoline, pyridine, indole, 2: 3 dihydroindole, benzofuran, coumarin, isocoumarin, benzothiophene, carbazole and thiodiphenylamine. Suitable non-aromatic or partially saturated ring structures include decalin (decahydronaphthalene), learned, cardine, borlylene. Suitable 3-dimensional compounds include, for example, norborene, bicycloheptane (norborane), bicyclooctane and bicyclooctene.

Both substituents X and Y are attached to related ring atoms in the ring having only one ring, or to associated 9,90349 ring atoms in one of the rings where the compound is polycyclic. In the latter case, this means that if naphthalene is used, these substituents cannot be attached at the 1,8 or 4,5 positions, but can be attached at the 1,2-, 2,3-, 3,4-, 5,6-, 6, To 7- or 7.8 positions.

These compounds are reacted to form esters, amines, amides, half esters / half amides, half esters or salts which are used as additives. Preferred additives are salts of a secondary amine having a hydrogen or carbon-containing group or groups containing at least 10, preferably at least 12 carbon atoms. Such amines or salts can be prepared by reacting the acid or anhydride described above with an amine, or by reacting a secondary amine derivative with carboxylic acids or anhydrides. In the preparation of amides from acids, dewatering and heating are generally necessary.

Alternatively, the carboxylic acid may be reacted with an alcohol having at least 10 carbon atoms or a mixture of alcohol and amine.

The groups containing the hydrogen and carbon atoms of the substituents are preferably hydroxyl groups, although halogenated hydrocarbyl groups containing preferably only a small number of halogen atoms (e.g. chlorine atoms), for example less than 20% by weight, could also be used. Hydrocarbyl groups are primarily aliphatic, e.g. alkylenes.

They are primarily straight-chain. Unsaturated hydrocarbyl groups, e.g. alkenyls, may also be used, but are not preferred.

Alkyl groups preferably have at least 10 carbon atoms, preferably 12 to 22 carbon atoms, for example 14 to 20 carbon atoms, and are preferably straight-chain or branched 1 or 2. Two positions. If branching occurs in more than 20% of the alkyl chains, the branches must be methyl. Other groups containing hydrogen and carbon may be shorter, e.g. containing less than 6 carbon atoms, or may have at least 10 carbon atoms if desired. Suitable alkyl groups include methyl, ethyl, propyl, hexyl, decyl, dodecyl, tetradecyl, eicosyl and docosyl (behenyl). Preferred alkyl groups include, but are not limited to, hexylene, octylene, dodesylene, and hexadylene.

In the primary structure where the intermediate has reacted with a secondary amine, one of the substituents is primarily an amine, and the other is an amine or a diammonium salt of a secondary amine. Particularly preferred additives are amides and amine salts of secondary amines.

In order to obtain the fuels of this invention, these additives are generally used in combination with other additives, and examples of these other additives include so-called "comb" polymers having the general formula

D H "J H

Il II

- c - c - c - c -

Il i

E G _ m | _K LJ 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 heterocyclic group, R'CO.OR K = H, CO.OR ', OCO.R', OR ', CO2H L = H, R ', CO.OR', OCO.R ', aryl, CO2H n = 0.0-0.6 (molar ratio) R> C1Q R' ^ C1

If necessary, another monomer can be terpolymerized.

When these other additives are copolymers of alpha-olefins and maleic anhydride, they are easiest to prepare by polymerizing the monomers without solvents, or in a solution of a hydrocarbon solvent such as heptane, benzene, cyclohexane or white oil at a temperature generally below 20 ° C. and usually accelerated with a peroxide or azotypic catalyst such as benzoyl peroxide or azo-diisobutyronitrile under the protection of an inert gas such as nitrogen or carbon dioxide to exclude oxygen. It is recommended, but not necessary, that equimolar amounts of olefin and maleic anhydride be used, although molar ratios in the range of 2: 1 and 1: 2 are suitable. Examples of olefins that can be copolymerized with maleic anhydride are 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octodecene.

The copolymer of olefin and maleic anhydride vi can be hindered by any suitable technique, and although it is preferred, it is not necessary that the maleic anhydride be at least 50% esterified. Examples of alcohols that can be used include n-decan-1-ol, n-tetradecan-1-ol, n-hexadecan-1-ol, n-octadecan-1-ol. The alcohols may also contain one methyl branch per chain, for example 1-methyl, pentadecan-1-ol, 2-methyl, tridecan-1-ol. The alcohol may be a mixture of ordinary and simple methyl branched alcohols. Each alcohol can be used to esterify copolymers of maleic anhydride and any olefin. It is preferable to use pure alcohols rather than commercially available alcohol mixtures, but when using mixtures refers to the average number of carbon atoms of the R 'alkyl group, if alcohols with a branch in the 1 or 2 position are used, refers to the straight chain backbone of the alcohol. When using mixtures, it is important that no more than 15% of the R 1 groups have the value R 1 + 2. The choice of alcohol naturally depends on the choice of olefin copolymerizable with maleic anhydride so that R + R * is in the range 18-38. The preferred value of R + R 1 depends on the boiling properties of the fuel for which the additive is used.

Either polymers may also be fumarate polymers and copolymers, such as those described in European Patent Applications 0153176, 0153177, 85301047 and 85301048.

Examples of other additives which may be used in combination with cyclic compounds are polyoxyalkylene esters, ethers, ester / ethers and mixtures thereof, in particular those containing at least one, preferably at least two C10-C30 linear saturated alkyl groups and a polyoxyalkylene glycol group having a molecular weight of 100-5 , preferably 200-5000, and the alkyl group of said polyoxyalkylene glycol contains 1 to 4 carbon atoms. These substances form the subject of European patent O 061 895 B. Other such additives are described in U.S. Patent 4,491,455.

Preferred esters, ethers or ester (s) useful in this invention may be structurally represented by the formula: R-O (A) -O-R "wherein R and R" are the same or different, and may be i) n-alkyl

II

ii) n-alkyl-C 0

II

iii) n-alkyl-O-C- (CF 2) 0 O

H II

iv) the n-alkyl-O-C (CF12) n-C-alkyl group is linear and saturated and contains 10 to 30 carbon atoms, and A represents a polyoxyalkylene block of glycol having 1 to 4 carbon atoms in the alkylene group, such as a polyoxymethylene, polyoxyethylene or polyoxytrimethylene moiety , which is substantially linear; some degree of branching to the lower side chains is tolerable, but it is recommended that the glycol be substantially linear, A may also contain nitrogen.

i3 90349

Suitable glycols are generally substantially linear polyethylene glycols (PEG) and polypropylene glycols (PPG) having a molecular weight of about 100-5000, preferably about 200-2000. Preferred are esters and fatty acids containing 10 to 30 carbon atoms are useful for reacting with glycols to form ester additives, and preferably C 1 -C 2 is used. fatty acids, especially behenic acids. Esters can also be prepared by esterification of polyethoxylated fatty acids or polyethoxylated alcohols.

Polyoxyalkylene diesters, diethers, ether / esters and mixtures thereof are suitable for use as additives with diesters in narrow boiling point distillates, while small amounts of monoethers and monoesters may be present and are often formed in the manufacturing process. In order to prepare additives, it is important that a large amount of the dialkyl compound be present. Mixtures of stearic or behenic diesters or polyethylene / polypropylene glycol are particularly preferred. The additives used may also contain an unsaturated copolymer of ethylene as flow improvers. Unsaturated monomers which can be copolymerized with ethylene include mono- and diesters of the general formula:

R6 H

c = c R 5 R 7 wherein is hydrogen or methyl, R 8 is a -OOCR 8 group, wherein R 6 is hydrogen or C 1 -C 6, most usually C 1 -C 6, 3a preferably C 1 -C 6, straight or branched chain alkyl; or R 1 is a -OOCRO group, wherein R 8 is as described above but is not hydrogen, and R 8 is hydrogen or -COOR 8 as defined above. When R ^ and R? are hydrogen and R 9 is -OOCR 8, the monomers include C 1 -C 4 vinyl alcohol esters C 1 -C 18 monocarboxylic acid, and primarily C 2 -C 2 M 'even more usually C 1 -C 18 monocarboxylic acid, and preferably C 1 -C 18 monocarboxylic acid . Examples of vinyl esters that can be copolymerized with ethylene 14,90349 include vinyl acetate, vinyl propionate, and vinyl butyrate, with vinyl acetate being preferred.

When used, we recommend that the copolymers contain 5-40% by weight of vinyl ester, preferably 10-35% by weight of vinyl ester. They may also be blends of the two copolymers described in U.S. Patent 3,961,916. It is recommended that these copolymers have a number average molecular weight of 1000-10,000, preferably 1000-5000, as measured by steam fractional osmometry.

The additives used may also contain other polar compounds, either ionic or non-ionic, which have the ability to act as inhibitors of the growth of wax crystals in fuels. Polar nitrogen-containing compounds have been found to be particularly effective when used in combination with glycol esters, ethers or ester / ethers. These polar compounds are generally amine salts and / or amides formed from at least one molar portion of a hydroxyl-substituted amine with a hydrocarbyl acid having 1 to 4 carboxyl groups or anhydrides thereof; esters / amides containing a total of 30-300, preferably 50-150 carbon atoms can also be used. These nitrogen compounds are described in U.S. Patent 4,211,534. Suitable amines are usually long chain (-: ^ 2-C40 Primary, secondary, tertiary and quaternary amines or mixtures thereof, but shorter chain amines may also be used provided that the resulting nitrogen compound is oil-soluble, and usually contains about 30 to 300 carbon atoms in total.The nitrogen compound preferably contains at least one straight-chain C8-C24 alkyl block.

Suitable amines include primary, secondary, tertiary and quaternary amines, but primary ones are secondary. Tertiary and quaternary amines can only form amine salts.

Examples of suitable amines include tetradecylamine, coconut amine, hydrogenated thallamine and the like. Examples of 90349 secondary amines include dioctadecylamine, methyl-behenylamine and the like. Amine mixtures are also suitable, and many amines derived from natural raw materials are mixtures.

The primary amine is a secondary hydrogenated thallium amine of the formula HNR.R wherein R and R are alkyl groups derived from hydrogenated tallow amine having a composition of approximately 4% C ^, 31% 59% C ^ g.

Examples of carboxylic acids (and their anhydrides) suitable for the preparation of these nitrogen compounds include cyclohexane, 1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, naphthalenedicarboxylic acid and the like. These acids generally have about 5 to 13 carbon atoms in the cyclic moiety. Preferred acids useful in this invention are benzenedicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid. Particularly preferred is phthalic acid or its anhydride. Particularly preferred compounds are amide amine salts formed by reacting 1 molar part of phthalic anhydride with 2 molar parts of dihydrated thallamine. Another preferred compound is a diamine formed by dehydration of this amide-amine salt.

In preparing the fuels of this invention, hydrocarbon polymers may be used as part of the combination to be added. They are described by the following general formula: “T H 1 'UH *

I I I I

--c - c ---- c - c--

I I I I

_t tJ vhuw where T = H or R 'U = H, T or aryl v = 1.0-0.0 (molar ratio) w - 0.0-1.0 (molar ratio) R ^ is normal, over lo carbon atoms alkyl group containing.

16 90349 These polymers can be prepared directly from ethylenically unsaturated monomers, or indirectly by hydrogenation of polymers made from other monomers such as isoprene and butadiene.

A particularly preferred hydrocarbon polymer is a copolymer of ethylene and propylene, preferably having an ethylene content of between 50% and 60% by weight.

The amount of additive required in preparing the distilled fuels of this invention will vary with the combustion oils, but will generally be 0.001 to 0.5% by weight, for example 0.01 to 0.1% by weight (active ingredient) based on the weight of the fuel oil. The additive is dissolved in the most suitable solvent to form a 20-90, e.g. 30-80% by weight concentrate in the solvent. Suitable solvents include kerosene, aromatic fuel oils, mineral lubricating oils, etc.

The present invention is illustrated by the following examples in which the size of wax crystals in fuels was measured by placing fuel samples in 60 ml bottles in refrigerators where they were kept for 1 hour above a cloud point of about 8 ° C until the fuel temperature stabilized. The cabinet was then cooled to a test temperature of 1 ° C per hour, which was then stored.

A prefabricated filter holder consisting of a 10 mm diameter sintered ring surrounded by a 1 mm wide annular metal ring supporting a 200 nanometer silver membrane filter held in place by two vertical rods is placed on top of the vacuum device. A vacuum of at least 80 kPa is developed and the cooled fuel is dropped onto the membrane with a clean drip pipette until a small dome-shaped liquid droplet just covers the membrane. Slowly drip fuel to strengthen the dome; after about 10-20 drops of fuel have been dripped, the hood is allowed to dry, leaving a thin non-polished matte wax cake of i7 90349 Mata fuel on the film. The thick layer of wax si rinses thoroughly, and the thin layer can be rinsed off. The optimal layer thickness depends on the shape of the crystals, with "leaf-like" crystals requiring thinner layers than "grain-like" crystals. It is important that the final cake looks matte. An "audible cake" indicates excessive fuel residue and "lubricity" of the crystals, and such a cake should be discarded.

The cake is then washed with a few drops of methyl ethyl ketone, which is allowed to dry completely. The procedure is repeated a few times. When the wash is complete, the methyl ethyl ketone disappears very quickly, leaving a brilliant "Matan-white" surface that turns gray upon the 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 under a scanning electron microscope. To protect the wax, it may be necessary to keep the sample refrigerated, in which case it should be stored in a cooling box that can be transported (in a suitable transport box) to the electron microscope to avoid the formation of ice crystals on the sample surface.

During coating, the sample must be kept as cold as possible to minimize damage to the crystals. electrical contact with the rack is best accomplished by a mounting screw that presses the circumferential ring onto the edge of a recess in the rack that is shaped to allow the surface of the sample to be toward the focal plane of the device. Electrically conductive paint can also be used.

After coating, the micrographs are placed in a scanning electron microscope in a conventional manner. To determine the average crystal size, the micrographs are analyzed by attaching a transparent 88-dot dot film on a suitable micrograph, overlaid with a regular, checkered grid of 8 rows and a column of 90 3 49 11. The magnification should be such that only a few of the largest crystals come in contact with more than one point, and a magnification of 4000-8000 has proven to be appropriate. The crystal must be measured at each point of the lattice, where the point touches the dimension of the crystal, the shape of which can be clearly defined.

The "decomposition" of the crystals is also measured in the same way as the Gaussian standard deviation to which Bessel's correction has been applied.

The wax content before and after the filter is measured using a differential scanning calorimetry DSC (such as e.g.

DuPont 9000 Series) capable of forming a curve of approximately 100 cm in area from 1% waxy fuel with a variation in the noise-induced output of the device with a standard deviation of less than 2% of the average output signal.

The DSC is calibrated using an additive that generates large crystals that can be reliably removed as a filter by circulating this calibration fuel in the ring at the test temperature and measuring the WAT of the fuel thus released from the wax by DSC. Samples of the fuel in the tank and the fuel after the filter are then analyzed by DSC and the area of each fuel above the baseline of the WAT determined with the calibration drip fuel is determined.

Ratio DSC area to sample after filter The area of DSC to the sample in the tank is the percentage of wax remaining after the filter.

The cloud point of distilled fuels was determined by a standard cloud point test (IP-219 or ASTM-D 2500), other measurements of the onset of crystallization are the wax onset point (WAP) test (ASTM-D. 3117-72) and the wax onset temperature (WAT), and is performed on a differential scanning calorimeter using a Mettler TA 2000B differential scanning calorimeter.

19 90349

The ability of the fuel to pass through the main filter of the diesel engine was determined with equipment consisting of a typical main filter of the diesel engine installed in the fuel line in a standard housing; suitable are the Bosch type used in the diesel engine of a 1980 VW Golf car, and the Cummins FF105, such as that used in the Cummins NTC engine series. The tank, which was able to store half of the fuel in a normal fuel tank, and the supply system that came from it was passed through a fuel injection pump used in VW Golf to suck fuel through a filter at a constant flow as in the engine. Gauges are placed in the equipment to measure the pressure drop in the fuel passing through, the flow rate in the injection pump, and the temperatures. Tanks are placed in the equipment to receive the pumped fuel, both "injected" fuel and excess fuel.

19 liters of fuel are placed in the fuel tank and the tank is tested for leaks. When everything is satisfactory, the air temperature is stabilized at 8 ° C above the cloud point of the fuel. The unit is then cooled to 3 ° C / hour to the specified test temperature and held for at least 3 hours to stabilize the fuel temperature. The container is shaken vigorously to disperse the wax therein; the tank is sampled and 1 liter of fuel is removed from the sampling point in the supply line immediately after the tank and returned to the tank. The pump is then started at a speed set to correspond to a speed of 110 km / h.

.. In the case of the VW Golf, this speed is 1900 rpm, which corresponds to an engine speed of 3800 rpm. The pressure drop in the filter and the flow rate of fuel from the injection pump are monitored until fuel is typically consumed in 30-35 minutes.

If the fuel supply to the injectors can be maintained at 2 ml per second (the amount of overflow fuel is about 6.5-7 ml / s), the result is "PASSED". A decrease in the flow rate of fuel pumped into the nozzles indicates a "LIMIT CASE" result, and a zero flow indicates a "FAILED" result.

2o 90 349

In general, the "PASSED" result is associated with an increased pressure drop in the filter, which can rise as high as 60 kPa. Generally, substantial amounts of wax must be passed through a filter to achieve such a result. The "WELL THROUGH" result is characterized by an experiment in which the pressure drop in the filter does not rise above 10 kPa, and is the first sign that most of the wax has passed through the filter, with an excellent result in a pressure drop below 5 kPa.

In addition, samples of "overflow" fuel and "fuel fed to the nozzles" are ideally taken every four minutes. These samples are compared together with the samples from the post-test tank to determine the DSC-fed filter-passed wax. Samples of the fuel are also taken before the test, and samples from the electron microscope are prepared from them and from the post-test samples for a true comparison of the size and species of the wax crystals.

The additives used were:

The 1, N-dialkylammonium salt of 2-dialkylamido-benzenesulfonate, wherein the alkyl groups are n-N-dialkylammonium salt, was prepared by reacting 1 mole of cyclic anhydride of orthosulfobenzoic acid with 2 moles of di (hydrogenated) thallamine at 50% w / v. The reaction mixture was stirred between 100 ° C and reflux temperature. The solvent and chemicals should be kept as dry as possible to prevent hydrolysis in the anhydride.

The product was analyzed by 500 MHz Nuclear Magnetic Resonance Spectroscopy, which confirmed the structure to be

O

II

- »<CV <CH2> 14/16-CH3> 2

Rot

SO3t -> <+> N „2 (CH2- (CH2> 14/16-CH3) 2 2i 90 3 49

Additive 2

A copolymer of ethyl and vinyl acetate, of which 17% by weight has a molecular weight of 3500 and has 8 methyl branches per 100 methyl groups in the side chains, measured at 500 MHz by NMR.

Additive 3

A styrene-dialkyl maleate copolymer prepared by esterifying a 1: 1 molar copolymer of styrene-maleic anhydride with 2 moles of a 1: 1 molar mixture of CH 2 OH and 1 z 2 , where p-toluenesulfonic acid (1/10 mole) in a toluene solvent was used as the catalyst, giving a number average molecular weight of 50,000 and containing 3% by weight of unreacted alcohol.

Additive 4 The dialkylammonium salts of 2-N, N-dialkylamidobenzoate were formed by mixing one molar portion of phthalic anhydride with two molar portions of dihydrated thallamine at 60 ° C.

The results were as follows:

Example 1

Fuel properties

Melting point -14 ° C

Wax on -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% by weight

Each of the additives 1, 2 and 3,250 ppm was charged to the fuel and the test temperature was -25 ° C. Wax crystals were found to be 1200 nanometers long, and more than 90% of the wax passed through Cummins' FF 105 filter.

During the experiment, the permeation of the wax was further observed by observing the pressure drop in the filter that faces! at only 2.2 kPa.

Example 2

The experiment of Example 1 was repeated, and the size of the wax crystals was found to be 1300 nanometers, and the maximum final pressure drop was 3.4 kPa.

Example 3

Fuel properties

Melting point 0 ° C

Wax appearance temperature -2.5 ° C

Initial boiling point 182 ° C

20% 220 ° C

90% 354 ° C

Final boiling point 385 ° C

Wax content at test temperature 1.6% by weight

Each additive 1, 2 and 3 was used at 250 ppm and the size of the wax crystals was found to be 1500 nanometers, and about 75% by weight passed the Bosch filter 145434106 at a test temperature of -8.5 ° C. The maximum pressure drop in the filter was 6.5 kPa.

Example 4

The experiment of Example 3 was repeated and the wax crystals were found to be 2000 nanometers in length, of which about 50% 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 of a mixture of Additive 1 and 100 ppm of Additive 2 and tested at -8 ° C as in Example 3 at a wax content of 1.4% by weight. The wax crystals were found to be 23,90349 2,500 nanometers in length, and 50% of the wax passed through the filter with a pressure drop of 67.1 kPa at most.

Comparative Example 6

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. The size of the wax crystals was found to be 6300 nanometers, and 13% by weight of the wax passed through the filter.

This test is one of the best among the examples that did not pass the filter.

Electron microscope scanning images of the wax crystals formed by the fuels of Examples 1-6 are shown in the corresponding Figures 1-6.

Therefore, Examples 1-6 show that if the crystals can pass through the filter reliably, higher wax concentrations can be created for higher fuel wax contents than has been possible so far, and also at lower temperatures below the wax detection point than has been possible so far. This is possible regardless of the design of the fuel system, such as the ability to recycle fuel from the engine to heat the feed fuel sucked from the fuel tank, regardless of the ratio of fuel fed to return fuel, main filter area to feed fuel flow, and pre-filters and screens.

Examples 1-3 show that crystal lengths of less than about 1800 nanometers with tested filters result in dramatically better fuel properties.

Example 7 In this example, additive 1 was added to a distilled fuel having the following properties: 90349 24

IBP (initial boiling point) 180 ° C

20% 223 ° C

90% 3 3 6 ° C

pBP (final boiling point) 365 ° C

Wax onset temperature (WAT) -5.5 ° C

Turbidity point -3.5 ° C

The following additives were also added to the distilled fuel for reference purposes:

Additive A: 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%, a number average molecular weight (Mn) of 2000, and a degree of side chain branching of about 2-3 methyl per 100 methyl groups measured by NMR at 500 MHz.

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

Additive C: Polyethylene glycol dibehenate with an average molecular weight of 600.

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

Additives were added in the amounts indicated in the table below, and the experiments were performed according to PCT, details of which are given below:

Programmed Cooling Test (PCT) This is a slow cooling test designed to match the pumping of stored fuel oil. The cold flow properties of fuel oil containing additives have been determined by PCT as follows. 300 ml of fuel have been uniformly cooled to a test temperature of 1 ° C / hour, and then the temperature has been kept constant. After 2 hours at the test temperature of 25 90349, about 20 ml of the surface layer is removed by suction to prevent the effect of unusually large wax crystals which tend to form on the oil / air interface during cooling. The wax precipitated in the flask is dispersed with gentle agitation and then poured into a Cfppt (1) filter assembly. Open the tap which creates a vacuum in the 500 mm column of mercury and close the tap when 200 ml of fuel has passed through a collecting vessel fitted with a filter scale: if the flow rate is too low, indicating that the filter is clogged.

Indicate the mesh number of the sieve passed in the test.

(1) CFPPT - Cold Filter Plugging Point Test (CFPPT) cold filter clogging point test is described in detail in the Journal of the Institute of Petroleum, Vol. 52, no. 510, June 1966, pages 173-185.

Table

Additive (molar ratio) Density PCT mesh number penetrated at -11 ° C 150 ppm 250 ppm (active _ _ _ substance) A 100 200 4 60 120 1 200 350 4/2 (4/1) 100 350 1/2 ( 4/1) 350 350 4 / C (9/1) 150 250 1 / C (9/1) 250 350 4 / D (9/1) 150 350 1 / D (9/1) 350 350 It can thus be seen that that when only one additive is added, the best results are obtained with additive 1, and when 1 i särvi nepare ja is used, the best results are obtained when the second pair is additive 1.

26 90 349

Example 8 The characteristics of the fuel used in this example are as follows:

IBP (initial boiling point) 190 ° C

20% 246 ° C

90% 346 ° C

FBP (final boiling point) 374 ° C

Wax appearance temperature -1.5 ° C

Turbidity point + 2.0 ° C

It was treated with 1000 ppm of the active ingredient of the following additives.

(E) A mixture of Additive 2 (1 part by weight) and Additive 4 (9 parts by weight).

(F) Ethylene-vinyl acetate copolymer additives under the trade name ECA 5920 of Exxon Chemicals.

(G) With a mixture of 1 part of additive 1 1 part of additive 3 1 part of additive D 1 part of additive K.

(H) A commercial ethylene-vinyl acetate copolymer additive marketed by Amoco under the name 2042E.

(I) BASF's commercial ethyl vinyl propionate copolymer additive Keroflux 5486.

(J) No additive.

(K) With a reaction product obtained from 4 moles of dihydrated thallium amine and a list of moles of pyromellitic anhydride. The reaction is carried out without solvent at 150 ° C with stirring under a nitrogen blanket for 6 hours.

27 90 349 The following properties of these fuels were then measured: (i) The ability of the fuel to pass through the main diesel fuel filter at -9 ° C, and the percentage of wax that passed through the filter with the following results:

Additive Clogging consumption% wax passed _ nut time_ _ E 11 minutes 18-30% F 16 minutes 30% G Not clogged 90-100% H 15 minutes 25% I 12 minutes 25% J 9 minutes 10% (ii) Pressure drop in the time specified in the main filter is shown graphically in Fig. 7.

(iii) The settling of the wax in the fuel was measured by cooling the fuel in a measuring beaker with a volume of 100 ml and an upper surface corresponding to 100% of the height of the fuel. The beaker is cooled to an initial temperature of 1 ° C / hour, preferably 10 ° C above the cloud point of the fuel, but not less than 5 ° C above the cloud point of the fuel, to a test temperature which is then maintained for a predetermined time. The test temperature and precipitation time depend on the application, i.e. diesel or fuel oil. The test temperature is generally 5 ° C below the cloud point, and the minimum time for cold precipitation at the test temperature is at least 4 hours. The test temperature should preferably be 10 ° C or more below the cloud point of the fuel, and the precipitation time should be 24 hours or more.

At the end of the precipitation period, the beaker is inspected, the height of any precipitated wax is measured visually above the bottom of the beaker (0 ml) and expressed as a percentage of the cocaine level (100 ml). Clear fuel can be seen above the precipitated wax crystals 28,90349, and this method of measurement is often sufficient to assess wax precipitation. Often the fuel is cloudy above the precipitated wax crystals, or the wax crystals appear to be denser in it than they are when approaching the bottom of the measuring glass. In that case, a more quantitative method of analysis is used. It carefully sucks and stores the top 5% (5 ml) of the fuel, sucks the next 45%, discards, sucks and stores the next 5%, sucks the next 35% and discards, and finally recovers the bottom lo% after heating to dissolve the wax crystals. . The art samples are then treated as surface, middle, and bottom samples, respectively.

It is important that the vacuum used in the suction is rather weak, i.e.

200 ml of water, and that the tip of the pipette is placed just on the surface of the fuel in order to avoid flows of liquid which could interfere with the wax concentrations in the various layers inside the beaker. The samples are then heated to 60 ° C for 15 minutes and examined with a differential scanning calorimeter as mentioned elsewhere herein.

DSC technology involves the use of a device such as the Dupont 9900 Series or the Mettler TA 2000B. The latter device was used here. 25 μl of sample is placed in the sample cell and standard kerosene is placed in the reference cell and cooled at a rate of 22 ° C / minute from 60 ° C to at least 10 ° C, preferably above 20 ° C wax temperature (WAT), and then cooled to 2 ° C. / minute about 20 ° C below WAT. The reference sample is run on unrecipitated uncooled fuel. In this case, the precipitation of the wax corresponds to WAT (or WAT = WAT precipitated sample - WAT original sample). Negative results indicate wax removal from the fuel, and positive values indicate wax enrichment by precipitation. The wax content can thus be considered as a measure of precipitation in these samples. This is expressed as% WAX or 4% WAX (Δ% WAX =% wax in the doped sample -% wax in the original sample), and again negative values of 29 90349 indicate wax removal from the fuel and positive values indicate wax enrichment by precipitation. These wax concentrations are derived by measuring the area under the DSC curve up to a specified temperature.

The fuel wax was cooled from 1 ° C / hour from + 10 ° C to -9 ° C and held for 48 hours before testing. The results were as follows:

Additive Visible wax Surface 5% WAT ° C values_ ____ _ _ Middle section 5% Bottom section 10% E Thoroughly cloudy, -10.80 -4.00 -3.15 base denser F On the surface 50% -13.35 -0.80 - 0.40 clear G 100% -7.85 -7.40 -7.50 H Surface 35% -13.05 -8.50 +0.50 clear I Surface 65% - clear J 100% half -6, 20 -6.25 -6.40 jellies (These results are also shown graphically in Figure 8).

Original WAT _WAT (° C) (Precipitated samples)

Unprecipitated Surface 5% Middle 5% Bottom 10% Fuel_ _ ___ J__ 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 the most effective additive (G) can achieve a visible reduction in WAT).

90 349 30% WAX (Precipitated samples) _

Surface 5% Middle section 5% Bottom 10% E -0.7 +0.8 +0.9 F -0.8 +2.1 +2.2 H -1.3 -0.2 +1.1 G + 0.0 +0.3 +0.1 J -0.1 +0.0 +0.1 (Note:% WAX has been measured by applying the original baseline, and measuring the area WAT from -25 ° C to it. Calibration has been performed with a previously known amount of crystallizing wax).

The results show that the crystal size is reduced by the presence of additives, the wax crystals settling relatively quickly. For example, when untreated fuels are cooled below their cloud point, they tend to show a small settling of the wax crystals because the plate-like crystals adhere to each other and cannot fall freely in the liquid and form a gelatinous structure. they tend to form a few tens of micrometers long needle-like crystals that can move freely in the liquid and settle relatively quickly.

This settling of wax crystals can cause problems in storage containers and vehicle systems. Condensed wax layers can be inadvertently absorbed into the system, especially when the fuel level is low or the tank mixes (eg when the vehicle is cornering), and the filter can become clogged.

If the size of the wax crystals can be further reduced to less than 10,000 nanometers, the crystals settle relatively slowly, and this can lead to non-settling of the wax, which gives advantages in terms of fuel properties compared to the case where the fuel contains settled wax crystals. If the size of the wax crystals 90349 31 can be reduced to an average of less than 4000 nanometers, the tendency of the crystals to settle during fuel storage is almost eliminated. If the size of the wax crystals is reduced to the optimum size of the claims, the wax crystals will remain soaked in the fuel for many weeks required in some storage systems, and the problems will be effectively eliminated.

(iv) The CFPP characteristics were as follows:

Additive CFPP temperature Decrease in CFPP E -14 11 F -20 17 G -20 17 H -20 17 I -19 16 -3 (v) The average crystal size formed was found to be:

Additive Size (Nanometers) E 4400 F 10400 G 2600 H 10800 T 8400 J Thin plates, medium 50000

Claims (5)

1. Distillate fuel oil boiling in the range of 120-500 ° C, characterized in that it has a wax content of at least 0.3% by weight at a temperature of 10 ° C below the wax formation temperature, and that the wax crystals at this temperature have an average particle size of less than 4000 nanometers. . 2. Distillate fuel according to claim 1, characterized in that the wax crystals have an average particle size of less than 3000 nanometers. 3. Distillate fuel according to claim 1, characterized in that the wax crystals have an average particle size of less than 2000 nanometers. 4. Distillate fuel according to claim 1, characterized in that the wax crystals have an average particle size of less than 1500 nanometers. 5. Distillate fuel according to claim 1, characterized in that the wax crystals have an average particle size of less than 1000 nanometers.