DE3634081A1 - FUEL OR FUEL OIL BASED ON PETROLEUM DISTILLATES - Google Patents

Description

The invention relates to an improved fuel or fuel oil based on petroleum distillates.

Mineral oils containing wax-like paraffin such as fuel or propellant oils from distillates in particular Middle distillates, such as diesel oil or heating oil, are used decreasing temperature of the oil less fluid. The reduction the flowability is based on crystallization of the paraffins to plate-shaped crystals, the one form sponge-like mass and enclose the oil in it; the temperature at which the wax crystals grow start forming, is called the cloud point and the temperature at which the paraffin deposits prevent oil from flowing as Pour point.

It is known that numerous additives lower the pour point work when they contain paraffinic mineral oils be mixed. Modify these connections the size and shape of the wax crystals and reduce the cohesive forces between the crystals and between the paraffin and the oil such that the oil remains flowable at lower temperatures and through through rough filters.

There are a variety of pour point depressants in described in the literature and commercially available. For example, U.S. Patent 3,048,479 teaches use of copolymers of ethylene and C₁ to C₅ vinyl esters such as vinyl acetate as the pour point depressant for fuels and especially for heating oils, diesel and jet fuel. There are also polymeric hydrocarbons based on ethylene and higher alpha-olefins e.g. B. propylene known as pour point depressant.  

In the 1960s to 1970s, more importance was attached the improvement of filterability. So teaches z. B. US Pat. No. 3,961,916 the use of a mixture of copolymers, to control the size of the wax crystals, and according to GB-PS 12 63 152 the size of the wax crystals should by using a copolymer with a small chain branch can be checked. Both systems improve the properties of the fuel, to go through filters like they did after Cold filter clogging point (CFPP) test are determined there instead of the plate-like formed without such additives Crystals now needle-shaped paraffin crystals generated that do not clog the pores of the filters, but form a porous filter cake on the filter and passage of the remaining liquid components allow.

Other additives are, for example, according to GB-PS 14 69 016 Copolymers of di-n-alkyl fumarates and vinyl acetate, the so far as pour point depressants for lubricating oils were used and now as additional additives with ethylene / vinyl acetate copolymers during the treatment of middle distillate fuels with a high final boiling point to improve the flow properties at lower Temperature can be used.

U.S. Patent 3,252,771 discloses the use of polymers from C₁₆ to C₁₈ alpha olefins, which from olefin mixtures, in which normal C₁₆ to C₁₈ alpha olefins predominate, by polymerization with aluminum trichloride / alkyl halide catalysts be obtained as the pour point depressant in distillate fuels with a broad Boiling range from easy to treat and in the fuels present in the United States in the early 1960s.  

It is also known to use olefin / Maleic anhydride copolymers to use. For example are copolymers according to US-PS 25 42 542 of olefins such as octadecene with maleic anhydride, that is esterified with an alcohol like lauryl alcohol, used as pour point depressant; furthermore according to GB-PS 14 68 588 copolymers of C₂₂ to C₂₈ olefins with maleic anhydride esterified with behenyl alcohol is used as a coadditive for distillate fuels.

Analogously, according to JP-PS 56 54 037 olefin / maleic anhydride copolymers, reacted with amines used as pour point depressant. According to JP-PS 56 54 038 derivatives of olefin / maleic anhydride Copolymers together with common middle distillate Flow improvers such as ethylene / vinyl acetate copolymers used.

JP-PS 55 40 640 discloses the use of olefin / maleic anhydride Copolymers that are not esterified, and requires that the olefins used exceed 20 Carbon atoms are said to contain CFPP activity to show.

According to GB-PS 21 92 012 mixtures of esterified Olefin / maleic anhydride copolymers and low molecular polyethylenes used while the esterified Copolymers as the only or sole additives are ineffective are. According to this reference, the olefin 10 to 30 carbon atoms and the alcohol 6 to 28 Contain carbon atoms, the longest chain in which alcohol contains 22 to 40 carbon atoms.

The improvement in CFPP effectiveness by the Incorporation of these known additives is based on a modification of the size and shape of the formed  Paraffin crystals, which are called needle-like crystals with a general particle size of 10 µm or larger and are generally formed from 30 to 100 microns. When operating diesel engines or heating systems at these crystals generally go to lower temperatures not through the filters, but form one permeable filter cake on the filter so that the liquid fuel can go through, the Paraffin crystals then dissolve when the diesel engine or the heating system has warmed up and the Most of the fuel from circulated fuel is heated. However, this can lead to the Paraffin crystals block the filters, causing difficulties when starting or starting and also problems when starting in cold weather or in the event of a breakdown of the preheating system for the fuel.

Surprisingly, it was found that paraffin Fuel or fuel oils, especially small wax crystals may contain that through the paper filter conventional diesel engines and heating systems can, if they receive certain additives.

The present invention has as its object a very specific improved fuel or fuel oil to propose. To solve this problem, such a Fuel or fuel oil based on petroleum distillates proposed a boiling range from 120 to 500 ° C, which is characterized in that at a Temperature of 10 ° C below the wax crystal formation temperature at least a paraffin content of less than 0.5% by weight and preferably less than 0.3% by weight and that the wax crystals at this temperature an average particle size less than 4000 nm (nanometers).  

The wax or paraffin formation temperature (WAT) of the fuel is measured using differential Calorimetry (DSC) determined. In this test, a small sample of a fuel of 25 µl with a Speed of 2 ° C / min. along with a comparative sample cooled the same thermal capacity, which however, no paraffin deposits in the relevant temperature range shows, such as kerosene. It an exothermic effect is observed when the crystallization starts in the rehearsal. For example, the WAT value of the fuel by extrapolation on one Mettler TA 2000 B device can be measured.

The paraffin content of the fuel or fuel oil or diesel or heating oil is recorded by the DSC through integration derived from the area derived from the baseline and the exothermic curve up to the specified Temperature is enclosed. The calibration is done beforehand with a known amount of a crystallizing paraffin carried out.

The average particle size of the wax crystals is by analyzing an electronically scanned photomicrograph a fuel sample at an enlargement determined from 4000 to 8000, with the longitudinal axis of 50 crystals measured in a predetermined grid becomes. It was found that the paraffin crystals with an average size of less than 4000 nm through conventional paper filters, such as those used in diesel engines used, go through with the fuel oil, although it is preferred to size below 3000 nm and preferably below 2000 nm and in particular below 1000 nm, the actually achievable Size of the origin of the fuel and the The type and amount of additive used depends however, it was found that these sizes and  even smaller ones can be achieved.

The possibility of such small paraffin crystals in Obtaining the fuel or fuel results in significant Advantages when operating diesel engines, what one by showing that one has to remove it beforehand fuel stirred from separated wax crystals through a diesel filter at 8 to 15 ml / sec. and 1.0 up to 2.4 liters per minute per m² filter area with one Temperature of at least 5 ° C below the paraffin formation temperature with at least 0.5% by weight of the fuel pumped through in the form of solid paraffin particles. Either both the fuel and the paraffin run successfully through the filter if one or more of the following Criteria are met:

• (i) when 18 to 20 liters of fuel through the Filters have gone through and the pressure drop preferably not more than 50 kPa on the filter 25 kPa and especially 10 kPa and at best Is 5 kPa;
• (ii) if at least 60% and preferably at least 80% and in particular at least 90 % By weight of the paraffin present in the fuel after the DSC test in the fuel is found that comes out of the filter;
• (iii) when pumping 18 to 20 liters Fuel through the filter has a flow rate which is always over 60% of the original Flow rate and preferably over 80% of this remains.

The proportion of crystals through the filter of the motor vehicle go through and the benefits are based on operation  on the small crystals and hang heavily depends on the crystal length, although also the crystal shape is important. It has been found that cube-like Crystals much easier through the filters go through as flat crystals and that when they do not pass through the filter, lower volume resistance form for the fuel. Still it is preferred crystal shape is a flat shape, generally it allows more paraffin to be deposited can if the temperature drops and that more Paraffin deposits before the critical crystal length is reached than in crystals of the same length cubic form would be the case.

The fuels according to the invention show excellent Advantages compared to previous middle distillate fuels, which by adding conventional additives in their Cold flow properties have been improved. For example are the fuels at temperatures in the neighborhood of the pour point are operational and will not limited by not meeting the CFPP test. As a result, they meet fuels the CFPP test at significantly lower temperatures or these test conditions do not have to at all be fulfilled. The fuels also have an improved one Cold start behavior at lower temperatures, since they are not on the circulation of warm fuel to dissolve the unwanted paraffin deposits are instructed.  

Distillate fuels with a general boiling range from 120 to 500 ° C fluctuate considerably in their boiling properties and its paraffin content, the extent, with which extremely small crystals are obtained can depend on the type and origin of the fuel itself and it is not with some middle distillates possible to produce extremely small crystals like this be requested according to the invention. The flow properties can be multiplied, however, so that such small Crystals can be obtained by, for example changes the working conditions at the refinery, so that you can use suitable additives.

Preferred additives to be used are substituted Hydrocarbon compounds of the general formula

in which
Y is either SO₃ ^- · N⁺ (R³) ₃, SO₂NR³- or SO₃-, and
X either Y or -CON (R³) -, -CO₂ ^- -, N⁺ (R³) ₃-, -R⁴-CO · O-, -NR³CO-, -R⁴O-, R⁴O · CO-, -R⁴-, - N (COR³) or N⁺ (R³) ₃ · Z ^- -;
Z ^- either -SO₃ ^- or -CO₂ ^- mean, and
R¹ and R² are alkyl, alkoxyalkyl or polyalkoxyalkyl radicals with at least 10 carbon atoms in the main chain, and
R³ is a hydrocarbon residue, which may be the same or different, and
R⁴ either has no meaning or is a C₁- to C₅ - an ethylene radical, with the grouping

the carbon-carbon bond is either (a) a can be ethylenically unsaturated bond if A and B alkyl, alkenyl or substituted hydrocarbon radicals are, or (b) part of a cyclic structure is aromatic, polynuclear aromatic or cycloaliphatic is.

When the O-C bond is part of a cyclic compound the ring atoms in it are preferably carbon atoms, however, can also heterocyclic compounds be in which the ring contains N, S or O atoms.

Examples of aromatic compounds, of which the Additives that can be made have the following Formula in which the aromatic group is substituted can be:

Alternatively, these compounds can be of polycyclic Connections are obtained from those who Two or more ring structures of various types to have. You can (a) condensed benzene structures, (b) condensed ring structures in which none or not all rings are benzene rings, (c) rings with their ends are connected, (d) heterocyclic compounds, (e) non-aromatic or partially saturated Ring systems or (f) three-dimensional structures.

Condensed benzene structures, of which the compounds can derive are, for example, naphthalene, Anthracene, phenathrene and pyrene. Condensed ring structures, where no ring or not all rings are benzene rings are, for example, azulene, indene, hydroindene, Fluorene or diphenylene. Connections where the Rings are connected at their ends, for example Diphenyl compounds.

Suitable hetercyclic compounds are derived, for example of quinoline, indole, 2: 3 dihydroindole, benzofuran, Coumarin and iso-coumarin, benzothiophene, carbazole and thiodiphenylamine.

Suitable non-aromatic or partially saturated Ring systems include decalin (decahydronaphthalene), alpha-pinene, cadine, bornylene. Suitable 3D dimensional Compounds include norbornene, bicycloheptane, (Norbornane), bicyclooctane and bicyclooctene.

The two substituents X and Y must be attached to the neighboring ones Ring atoms are in the ring, if only one ring is present, or on adjacent ring atoms in one of the rings when the compound is a polycyclic compound is. In the latter case, this means that at Naphthalene compounds do not have these substituents in  the 1.8 or 4.5 position, but in the 1.2, 2,3-, 3,4-, 5,6-, 6,7- or 7,8 position.

These compounds are reacted to form esters, amines, Amides, half esters / half amides, half ethers or salts give that can be used as additives. Preferred Additives are salts of secondary amines, which a group containing hydrogen and carbon with at least 10 and preferably 12 carbon atoms contain. Such amides or salts can be produced in this way be that the acid or an anhydride with a secondary amine or alternatively an amine derivative with a carboxylic acid or an anhydride. The removal of water and heating are general required to remove the amides from the acids receive. Alternatively, the carboxylic acid can be combined with a Alcohol containing at least 10 carbon atoms or with a mixture of an alcohol or an amine be implemented.

The residues containing hydrogen and carbon in the substituents there are preferably hydrocarbon radicals, albeit halogenated hydrocarbon residues can be used and preferably those which only have a small proportion of halogen atoms, e.g. B. chlorine atoms contain, for example, less than 20 wt .-% lies. The hydrocarbon residues are preferred aliphatic radicals, such as alkylene. You are preferred straight chain. Unsaturated hydrocarbon residues like Alkenyl can be used but are not prefers.

The alkyl radicals preferably have 10 to 22 carbon atoms, such as 14 to 20 carbon atoms and are preferably straight-chain or in the 1- or 2-position branched. The other hydrogen and carbon  containing groups may be shorter, for example contain less than 6 carbon atoms or can optionally have at least 10 carbon atoms to have. Suitable alkyl radicals include methyl, Ethyl, propyl, hexyl, decyl, dodecyl, tetradecyl, eicosyl and Docosyl (Behenyl).

In a preferred embodiment, in which the intermediate is reacted with the secondary amine one of the substituents is preferably an amide and the other substituent is an amine or a dialkylammonium salt of the secondary amine.

Preferred additives are amides or amine salts of secondary Amines.

In order to obtain the fuels according to the invention they generally in combination with other additives used. Examples of such other additives are the compounds known as comb polymers uses the following general formula:

in which

D = R, CO-OR, OCO · R, R'CO · OR or OR E = H or CH₃ or D or R ′ G = H or D m = 1.0 (homopolymer) to 0.4 (molar ratio) J = H, R ′, aryl radical or a heterocyclic radical, R′CO · OR K = H, CO · OR ′, OCO · R ′, OR ′, CO₂H L = H, R ′, CO · OR, OCO · R ′ , Aryl, CO₂H n = O, 0 to 0.6 (molar ratio) R C₁₀ R ′ C₁

is.

If necessary, other monomers can also be terpolymerized be.

If these other additives are copolymers of alpha olefin and are maleic anhydride, then they can easily Way by polymerizing the monomers without solvent or in a solution of a hydrocarbon solvent, such as heptane, benzene, cyclohexane or white oil at temperatures in the general range of 20 to 150 ° C. mostly using a peroxide or an azo catalyst, such as benzoyl peroxide or azo-di-isobutyronitrile under an inert gas jacket made of nitrogen or carbon dioxide manufactured to prevent access to oxygen will. Preferably, but not necessarily, equimolar Amounts of the olefin and maleic anhydride are used, although molar proportions in Range of 2: 1 and 1: 2 are suitable. Examples of Olefins that copolymerize with maleic anhydride can be 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene and 1-octodecene.

The copolymers of olefins and maleic anhydride can be esterified in a customary manner, but preferably, but not absolutely necessary, the maleic anhydride is at least 50% esterified. Examples of alcohols that can be used are n-decan-1-ol, n-dodecan-1-ol, n-tetradecan-1-ol, n-hexadecan-1-ol, n-octadecan-1-ol. The alcohols can also contain up to one methyl branch per chain, such as 1-methyl-pentadecan-1-ol, 2-methyltridecan-1-ol. The alcohol can be a mixture of a normal and a single methyl branched alcohol. Any alcohol can be used to esterify the copolymers of maleic anhydride with the olefins. Pure alcohols are preferably used instead of the commercially available alcohol mixtures, but when mixtures are used, R 1 refers to the average number of carbon atoms in the alkyl radical; when alcohols with branches in the 1- or 2-position are used, R1 refers to the straight-chain portion of the alcohol. When using mixtures, it is essential that no more than 15% of the R¹ residues have a value of r¹ + 2. The choice of alcohol naturally depends on the choice of the olefin to be copolymerized with maleic anhydride so that R + R 1 is in the range of 18 to 38. The preferred value of R + R¹ depends on the boiling properties of the fuel in which the additive is used.

The comb polymers are also fumarate / vinyl acetate and especially those in European patent applications 01 53 176, 01 53 177 and 85 301 047 and 85 301 048 and esterified olefin / maleic anhydride copolymers and the polymers and copolymers of alpha olefins and esterified copolymers of styrene and maleic anhydride.

Examples of other additives that can be used together with the cyclic compounds can be used  Polyoxyalkylene esters, ethers, esters / ethers and their Mixtures, especially those containing at least 1 and preferably 2 linear saturated C₁₀ to C₃₀ alkyl radicals and a molecular weight polyoxyalkylene glycol residue from 100 to 5000, preferably 200 to 5000 contain, wherein the alkyl radical in the polyoxyalkylene glycol Contains 1 to 4 carbon atoms. These connections are in European patent application 00 61 895 B described. Other such additives are in U.S. Patent 44 91 455.

The preferred esters, ethers or esters / ethers used can be represented by the following structural formula express:

R-O (A) -O-R ′ ′,

in which R and R ′ ′ are the same or different and the can have the following meaning:

where the alkyl radicals are linear and saturated and 10 contain up to 30 carbon atoms and where A is a polyoxyalkylene portion of the glycol in which the Alkylene group has 1 to 4 carbon atoms, such as polyoxymethylene,  Polyoxyethylene or polyoxytrimethylene, the are essentially linear. A certain degree of branching the lower alkyl side chains as with polyoxypropylene glycol can be tolerated, but should the glycol be substantially linear. A can too contain a nitrogen atom.

Suitable glycols are generally the essentially linear polyethylene glycols (PEG) and polypropylene glycols (PPG) with a molecular weight of about 100 to 5000 and preferably 200 to 2000. Esters are preferred, and fatty acid containing 10 to 30 carbon atoms are suitable for implementation with the Glycols to form the ester additives, preferably C₁₈ to C₂₄ fatty acids and especially behenic acids be used. The esters can also be esterified of polyethoxylated fatty acids or polyethoxylated Alcohols are produced.

Polyoxyalkylene diesters, diethers, ethers / esters and their Mixtures are suitable additives, the diesters are preferred for narrow-boiling distillates, while Smaller amounts of monoethers and monoesters are still present can be and often formed during manufacture will. For the behavior of the additives it is essential that a larger amount of the dialkyl compound is present is. In particular, stearic acid or behenic acid diesters of polyethylene glycol, polypropylene glycol or Polyethylene / polypropylene glycol blends preferred.

The additives can also be mixed with ethylenically unsaturated Ester copolymers that are flow improvers are used will. The unsaturated monomers with ethylene can be copolymerized include unsaturated Mono- and diesters of the following general formula:  

in which R₆ is hydrogen or a methyl radical, R₅ is one -OOCR₈ group and R₈ a hydrogen format or a C₁ to C₂₈ radical and usually a C₁ to C₁₇ and preferably a C₁ to C₈ alkyl radical with a straight or branched chain is; or R₅ is a -COOR₈ group, in which R₈ has the meaning mentioned above, but not Is hydrogen, and R₇ is hydrogen or -COOR₈ in the above meaning. The monomer closes if R₆ and R₇ are hydrogen and R₅ -OOCR₈ are vinyl alcohol esters from C₁- to C₂₉- and usually C₁- to C₁₈- and preferably a C₂ to C₅ monocarboxylic acid. Examples of vinyl esters copolymerized with ethylene are vinyl acetate, vinyl propionate and Vinyl butyrate or isobutyrate, with vinyl acetate preferred becomes. The copolymers preferably contain 5 to 40 and preferably 10 to 35% by weight vinyl ester. You can can also be mixtures of two copolymers, for example is described in US-PS 39 61 916. Preferably these copolymers have an average Molecular weight, determined by vapor phase osmometry from 1000 to 10,000 and preferably 1000 to 5000.

The additives can also be other polar compounds contain, namely ionic or nonionic compounds, which in the fuels as inhibitors for the crystal growth of the wax crystals act. Here are particularly polar nitrogen-containing compounds  suitable when in combination with the glycol esters, ethers or esters are used, such mixtures of three components for Scope of the invention include. These polar connections are generally amine salts or amides that pass through the conversion of at least one molar portion of a hydrocarbon substituted amine with a molar proportion of a carboxylic acid with 1 to 4 carboxylic acid groups or their anhydrides are obtained; it can also esters / amides are used, the 30 to 300 and preferably contain 50 to 150 carbon atoms in total. These nitrogen compounds are in US-PS 42 11 534. Suitable amines are generally long chain primary, secondary, tertiary or quaternary C₁₂- to C₄₀ amines or mixtures thereof, but can shorter-chain amines can also be used, provided that the resulting nitrogen compound is oil soluble is therefore generally about 30 to 300 carbon atoms total contains. The nitrogen compound preferably contains at least one straight chain C₈ to C₂₄ alkyl sections.

Suitable amines are primary, secondary, tertiary or quaternary amines, but secondary amines are preferred. Tertiary and quaternary amines can only amine salts form. Examples of amines include tetradecylamine, Cocosamine, hydrogenated tallow amine and the like. Examples of secondary amines include Dioctadecylamine, methylbehenylamine and the like. Mixtures of amines can also be used, and numerous Amines derived from natural substances, are such mixtures. The preferred amines are secondary hydrogenated tallow amines of the general formula HNR₁R₂, where R₁ and R₂ are alkyl residues of hydrogenated tallow fat are and approximately from 4% C₁₄, 31% C₁₆, 59% C₁₈ shares consist.  

Examples of suitable carboxylic acids and their anhydrides for the preparation of these nitrogen compounds are under other cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2- dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, naphthalene carboxylic acid and the same. Generally these have Acids 5 to 13 carbon atoms in the cyclic residue. Preferred acids are benzenedicarboxylic acids such as phthalic acid, Isophthalic acid and terephthalic acid, with phthalic acid or its anhydride is particularly preferred. The special preferred compound is the amide amine salt, which by reacting a molar portion of phthalic anhydride with two molar proportions of dihydrated Tallow amine is obtained. Another preferred connection is the diamide, which is caused by dehydration this amide amine salt is obtained.

Hydrocarbon polymers can also be part of the Additive combination of the following general formula be used:

in which

T = H or R ′ U = H, T or an aryl radical v = 1.0 to 0.0 (molar ratio) w = 0.0 to 1.0 (molar ratio)

and wherein R 'is an alkyl radical.  

These polymers can be obtained directly from ethylenically unsaturated Monomers or indirectly by hydrogenation of monomers, polymers obtained such as isoprene, butadiene, etc. will.

Hydrocarbon polymers are particularly preferred Copolymers of ethylene and propylene with an ethylene content of preferably 20 to 60% by weight, generally be produced by homogeneous catalysis.

The amount of additive used to produce the invention Distillate fuel or propellant oil required depends on the type of propellant, but lies generally in a range of 0.001 to 0.5% by weight and for example at 0.01 to 0.1% by weight of active substance, based on the weight of the fuel. The Additive is usually added in a suitable solvent to a concentrate with 20 to 90 z. B. 30 to 80% by weight dissolved. Suitable solvents are kerosene, aromatic Naphtha compounds, mineral lubricating oils and the like.

The invention is illustrated by the following examples, being the size of the wax crystals in the fuel was determined by taking fuel samples in Bottles of 57 cm³ in cool containers at about 8 ° C above the cloud point of the fuel for about 1 hour, to stabilize the fuel temperature. The container was then heated to 1 ° C per hour Test temperature cooled and then at this temperature leave. A previously prepared filter holder from one sintered ring with a diameter of 10 mm, the surrounded by a 1 mm wide circular metal ring was holding a membrane filter rated at 200 nm made of silver, fastened by two vertical pins  and was placed in a vacuum device. A vacuum of at least 30 kPa was applied and the cooled fuel from a clean dropper dripped onto the membrane until the membrane of a small Pool was covered. The fuel was slowly added dropwise to maintain this pool of oil. After application from about 10 to 20 drops of fuel, the pool was left drain off a thin non-shiny layer of wet paraffin cake left on the membrane. A too thick a layer of paraffin will not give an acceptable wash and a too thin layer can be washed away. The optimal layer thickness depends on the crystal shape, where sheet-like crystals have a thinner layer than need nodular crystals. It is essential that the final filter cake has a matt appearance. A shimmering filter cake shows too much of residual oil and smearing of the crystals, so this cake should be discarded.

The cake is then covered with a few drops of methyl ethyl ketone washed, which is allowed to run off completely. This is carried out several times. When washing is finished, disappears the methyl ethyl ketone very quickly and leaves a shiny matt white surface back when applied another drop of methyl ethyl ketone turns gray.

The washed sample is then placed in a cold desiccator given and left there until the coating in the SEM can be done. It may be necessary to do this sample left under cooling to protect the crystals; you can in this case in a cooling chamber in front of the Transfer to the SEM with a suitable transport container store to form ice crystals on the surface to avoid the sample.

During coating, the sample must be as cool as possible be held to destroy the crystals  reduce. The electrical contact with the stage will best possible with a locking screw that the circular ring against the side of a recess presses, which is provided so that the surface of the Sample lies on the focal plane of the instrument. Man can also use electrically conductive paint.

If the sample is coated, the photomicrographs can be taken in a similar way with an electronic scanning microscope be preserved. The microphotographs are analyzed, to determine the average crystal size by making a transparent film with 88 marks in the form of dots at the interfaces of a uniform 8 rows and 11 rows. The Magnification should be chosen so that only some of the largest crystals are touched by more than one point, 4000 to 8000 times magnification is suitable. The crystal can be measured at each grid point, if the point touches a crystal dimension, its Shape can be clearly defined. It is called distribution spread the Gaussian standard deviation of the crystal length provided with a correction according to Bessel.

The wax content before and after the filter is checked with a Differential scanning calorimeter DSC (e.g. du Pont device 9900) measured, an area with a range of about 100 cm² / 1% fuel in the form of paraffin with an instrument with a noise-induced change in output with a standard deviation of less is sampled as 2% of the main output signal.

The DSC device is calibrated with an additive, which produces large crystals that are safe from the filter too are removed, using this for calibration Fuel at the test temperature in the device  can run through and the WAT value of the dewaxed Measures propellant oil with the DSC. The samples of the fuel from the tank and the one taken up after the filter The fuel is then analyzed with the DSC device; for each fuel, the area is above the baseline up to the WAT value of the calibration Determined fuel.

The percentage of paraffin that remains after the filter results from the ratio of:

The cloud point of the distillate fuel became after a standard procedure (IP-219 or ASTM-D 2500); the further provisions for the start of crystallization are the Paraffin Training Point (WAT) test after ASTM D. 3117-72 and the wax formation temperature (WAT), by differential scanning calorimetry with a Mettler TA 2000B device, namely a differential scanning calorimeter was measured.

The ability of the fuel through a main filter Going through a diesel engine was done in a fixture determined from a usual main filter of a diesel engine which existed in a standard housing the fuel supply line was attached. Suitable for this are Bosch filters as used in VW Golf Diesel cars (1980) and in a Cummins FF105 from the Cummins NTC series be used. A storage container and a feed system, with which half the fuel of a normal one Diesel fuel tank was able to supply to a Injection pump as used in the VW Golf car is used to filter the fuel through the the tank with a constant flow rate  how to promote in the vehicle. There were also instruments attached to the pressure drop across the filter, the flow rate from the injection pump and the temperatures to measure in the unit. There were also receptacles provided to the pumped fuel, namely both the injected fuel and the excess fuel to record.

During the test, the tank was filled with 19 kg of fuel and checked for leaks. Then the temperature at an air temperature of about 8 ° C above of the cloud point of the fuel stabilized. The Unit was then set to the desired one at 3 ° C per hour Test temperature cooled and at least 3 hours like this held to stabilize the fuel temperature. The tank was shaken vigorously to the existing one Disperse wax completely. It became a rehearsal removed from the tank and 1 liter of fuel in one Test point on the outlet line immediately after removed from the tank and returned to the tank. The pump was then started, with the circulation rate has been set to: their number of revolutions per minute corresponded to a pump output, that a driving speed of 110 km / h. corresponded. This value was in one area for the VW Golf of 1900 rpm corresponding to a number of revolutions of the Motors from 3800 rpm. The pressure drop across the filter and the flow rate of fuel from the injection pump were recorded until the last fuel was consumed was, which was generally the case after 30 to 35 minutes.  

If the fuel supply for injection at 2 ml / s can be kept and the additional fuel supplied is in an amount of 6.5 to 7 ml / s, is the test is marked "passed". A drop in the Fuel supply to the injector is considered a "limit case" judged as having no fuel supply at all "failed".

Usually one is marked as "passed" Test also to find an increasing pressure drop across the filter which can be up to 60 kPa. In general need significant amounts of crystallized paraffin pass the filter before achieving such a result becomes. The rating "passed" is if in the course of the test the pressure drop across the filter does not rise above 10 kPa, which is the first indication of this is to be assessed that the majority of the paraffins by the filter has gone, giving an excellent result is achieved when the pressure drop is below 5 kPa.

In addition, fuel samples are taken from the excess fuel and the fuel supplied to the injector taken, preferably every 4 minutes in the course of the entire experiment. These samples along with the Samples taken from the tank before the test are run through DSC compared to the proportion of paraffin supplied determine which one went through the filter. Samples of the fuel taken before the test are taken also taken and SEM samples are taken after Test taken to determine the crystal size of the paraffin and its type under actual conditions of use determine.

The following additives were used:  

Additive 1

The N, N-dialkylammonium salt of 2-dialkylamidobenzenesulfonate with alkyl residues of nC₁₆-C₁₈ H _{33-37 was} prepared by mixing one mole of the cyclic anhydride of orthosulfobenzoic acid with 2 moles of di- (hydrogenated) tallow amine in xylene as solvent with a 50% by weight. % concentration was implemented. The reaction mixture was stirred between 100 ° C and reflux temperature, the solvent and the compounds being kept as dry as possible in order to suppress hydrolysis of the anhydride.

The reaction product was analyzed by NMR at 500 MHz and showed a spectrum as shown in FIG. 1, which confirmed the following structure.

Additive 2

A copolymer of ethylene and 17% by weight vinyl acetate with a molecular weight of 3500 and a side chain branch of 8 methyl residues per 100 methylene groups, which were determined by NMR at 500 MHz.  

Additive 3

This was prepared by esterification of a 1: 1 molar styrene / maleic anhydride copolymer of a 1: 1 molar mixture of C₁₂H₂₅OH and C₁₄H₂₉OH per mole of anhydride groups, a slight excess of about 5% of alcohol being present. The esterification was carried out using p-toluenesulfonic acid as catalyst (1/10 mol) in xylene as solvent, a product with a molecular weight (Mn) of 50,000 being obtained which contained 3% by weight of untreated alcohol.

Additive 4

A dialkylammonium salt of 2-N, N-dialkylamidobenzoic acid, by mixing 1 mole of phthalic anhydride with 2 moles of dihydrogenated tallow amine was obtained at 60 ° C.

example 1

The fuel used had the following properties:

Cloud point -14 ° C CFPP, untreated-16 ° C Crystal training point-18.6 ° C Initial boiling point 178 ° C 20% bp 230 ° C 90% bp 318 ° C Final boiling point 355 ° C Paraffin content at -25 ° C1.1% by weight

There was an additive combination of 250 ppm each of the Additives 1, 2 and 3 added to the fuels and at -25 ° C tested. The crystal size of the paraffin was included 1200 nm in length, and more than 90% by weight of the paraffin went through the Cummins FF105 filter.  

During the trial, the passage of paraffin further demonstrated by having the pressure drop observed on the filter, which only increased by 2.2 kPa.

Example 2

Example 1 was repeated, the crystal size of the paraffin at 1300 nm and the maximum pressure drop was determined on the filter with 3.4 kPa.

Example 3

An oil with the following properties was used:

Cloud point 0 ° C CFPP, untreated -5 ° C Crystal training point-2.5 ° C Starting boiling point 182 ° C 20% Sdp220 ° C 90% 354 ° C Final boiling point 385 ° C Paraffin content at -25 ° C1.1% by weight

250 ppm of the additive 1, 2 and 3 were the Fuel added and the paraffin crystal size with 1500 nm was determined, it being found that 75% by weight of the paraffin through a Bosch filter 145434106 at one Test temperature of -8.5 ° C went through. The maximum pressure drop on the filter was 6.5 kPa.

Example 4

Example 3 was repeated, with a paraffin crystal size of 2000 nm in length, of which about 50% by weight through the filter with a maximum pressure drop of 35.3 kPa occurred.  

Example 5

The fuel according to Example 3 was 400 ppm of Product according to Example 1 and 100 ppm of A1 added, the fuel being examined as in Example 5 at -8 ° C was and at this temperature the paraffin content 1.4 % By weight. The paraffin crystal size was 2500 nm and 50% by weight of the paraffin entered through the filter a pressure drop of 67.1 kPa.

Example 6 (Comparison test)

The fuel according to Example 3 became one with 500 ppm Mixture of 4 parts of additive 4 and 1 part of the additive 2 treated; this fuel was tested at -8 ° C, it was found that the paraffin crystal size was 6300 nm and 13 wt .-% of the paraffin went the filter.

This example is based on one of the best examples the state of the art, with excellent results were found without penetration of the crystals.

A scanning electron micrograph of the wax crystals that form in the fuels according to Examples 1 to 6 are shown in FIGS. 1 to 6.

Examples 1 to 4 show if the crystals are reliable go through the filter that the excellent cold temperature behavior for higher paraffin contents than before can be expanded and also to temperatures that are far below the paraffin formation temperature,  than was previously possible. This is possible without having to consider the fuel system, like being able to warm up fuel from the engine of the fuel supplied from the fuel tank is taken back, as well as the ratio from supplied fuel to the returned fuel, the ratio of the main filter surface to that supplied fuel and the size and position of the Pre-filters and screens.

Examples 1-3 show that in the examined Filter crystal lengths below about 1800 nanometers into one leads to significantly better behavior of the fuel.

Claims (5)

1. propellant or fuel oil based on petroleum distillates with a boiling range from 120 to 500 ° C containing paraffins, characterized in that the propellant or fuel oils have a paraffin content of at least 0 at a temperature of 10 ° C below the paraffin formation temperature, 3 wt .-%, and that the wax crystals at this temperature have an average particle size of less than 4000 nm (nanometers). 2. propellant or fuel oil according to claim 1, characterized characterized in that the paraffin crystals have an average Particle size less than 3000 nm to have. 3. propellant or fuel oil according to claim 1, characterized characterized in that the paraffin crystals have an average Particle size less than 2000 nm to have. 4. propellant or fuel oil according to claim 1, characterized characterized in that the paraffin crystals have an average Particle size less than 1500 nm to have.   5. propellant or fuel oil according to claim 1, characterized characterized in that a particle size of less than 1000 nm.