EP3913035A1

EP3913035A1 - Novel compositions for reducing crystallization of paraffin crystals in fuels

Info

Publication number: EP3913035A1
Application number: EP21172949.6A
Authority: EP
Inventors: Ivette Garcia Castro; Miran Yu; Aleksandra Martyna GAJDA; Sandra Gloria KOENIG
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2020-05-20
Filing date: 2021-05-10
Publication date: 2021-11-24

Abstract

The invention relates to novel compositions for reducing crystallization of paraffin crystals in fuels.

Description

The invention relates to novel compositions for reducing crystallization of paraffin crystals in fuels.
Middle distillate fuels of fossil origin, especially gas oils, diesel oils or light heating oils, which are obtained from mineral oil, have different contents of paraffins according to the origin of the crude oil. At low temperatures, there is precipitation of solid paraffins at the cloud point ("CP"). It is thought that, in the course of further cooling, the platelet-shaped n-paraffin crystals form a kind of "house of cards structure" and the middle distillate fuel ceases to flow even though its predominant portion is still liquid. The precipitated n-paraffins in the temperature range between cloud point and pour point ("PP") considerably impair the flowability of the middle distillate fuels; the paraffins block filters and cause irregular or completely interrupted fuel supply to the combustion units. Similar disruptions occur in the case of light heating oils.
It has long been known that suitable additives can modify the crystal growth of the n-paraffins in middle distillate fuels. Additives of good efficacy prevent middle distillate fuels from already solidifying at temperatures a few degrees Celsius below the temperature at which the first paraffin crystals crystallize out. Instead, fine, readily crystallizing, separate paraffin crystals are formed, which, even when the temperature is lowered further, pass through the filters in motor vehicles and heating systems, or at least form a filtercake which is permeable to the liquid portion of the middle distillates, so that disruption-free operation is assured. The efficacy of the flow improvers is typically expressed, in accordance with European standard EN 116, indirectly by measuring the cold filter plugging point ("CFPP"). Cold flow improvers or middle distillate flow improvers ("MDFIs") of this kind which are used have long included, for example, ethylene-vinyl carboxylate copolymers such as ethylene-vinyl acetate copolymers ("EVA").
Alkylphenol-aldehyde resins in combination with other additives are known to improve the flow properties of paraffine containing mineral oils and mineral oil derivatives, see e.g. EP 857776 A1 .
However, it is a disadvantage of alkylpenol-formaldehyde resins that the resins may contain small amounts of free formaldehyde which requires safety measures during handling.
It was an object of the present invention to provide better alternatives to such alkylphenol-aldehyde resins with further improved properties and less formaldehyde content.
Reaction products of acetylene and p-tert.-butylphenol are known to improve the pour depressing properties of oils, see US 2474342 .
The problem was solved by mixtures of

(A) reaction products of acetylene and p-alkylphenols with
(B) at least one cold flow improver.

Another object of the invention is the use the mixtures according to the present invention for reducing crystallization of paraffin crystals in fuels and/or improving the cold flow properties of fuels.
Another object of the invention are middle distillate fuels comprising these mixtures.

Component (A)

Component (A) are reaction products of acetylene and p-alkylphenols which primarily comprise repeating units of formula (I)
wherein, R² in formula I is a linear or branched, saturated or unsaturated aliphatic hydrocarbon group with 2 to 100 carbon atoms. In a particularly preferred embodiment of the invention R² in is a linear or branched, saturated aliphatic hydrocarbon group with 3 to 20, more preferably from 4 to 16 carbon atoms.
R² is preferably substituted mainly in para position to the phenolic OH-group.
Preferred examples of R² are ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and tert-butyl, n-pentyl, tert-pentyl, n-hexyl, 2-ethylhexyl, 2-propylheptyl, n-octyl, iso-octyl, n-nonyl, iso-nonyl, n-decyl, iso-decyl, n-undecyl, iso-undecyl, n-dodecyl, iso-dodecyl, n-tridecyl, iso-tridecyl, n-tetradecyl, iso-tetradecyl, n-hexadecyl, iso-hexadecyl, n-octadecyl, iso-octadecyl, and eicosyl.
More preferred examples of R² are iso-propyl, iso-butyl, sec-butyl, tert-butyl, tert-pentyl, n-octyl, n-nonyl, n-decyl, n-dodecyl, n-tetradecyl, and n-hexadecyl.
Especially preferred examples of R² are iso-propyl, tert-butyl, and tert-pentyl.
In one embodiment the substituents R² are preferably derived from oligomers or polymers of propene or iso-butene, e.g. trimers, tetramers, pentamers or hexamers of propene or dimers, trimers or tetramers of iso-butene or n-butene.
In a preferred embodiment R² can be derived from an iso-butene containing polymer, preferably a homopolymer of iso-butene, with a weight average molecular weight Mw of 225 to 1400 g/mol, preferably 350 to 1300, more preferably 500 to 1200, and most preferably 600 to 1100 g/mol.
Components (A) may be obtained by reacting a phenolic compound of formula R²-C₆H₄-OH with acetylene. In this reaction acetylene adds to a carbon atom of R²-C₆H₄-OH (usually the carbon atom in ortho position to the OH group) followed by reaction of the obtained vinyl group with further R²-C₆H₄-OH. The obtained resin may to some extent be crosslinked as further acetylene might add to the less reactive meta position.
Most preferred resin is Koresin®, a resin marketed by BASF, and which is obtainable by reacting acetylene and para tertiary butyl phenol.
Therefore, component (A) primarily comprises units of formula (I)
Due to an alternative integration of the acetylene in the reaction component (A) may further comprise (see e.g. A. O. Zoss et al., Industrial and Engineering Chemistry, 41, 1949, 73 - 77) units of formula (II)
and/or terminal groups of formula (III)
The resin may comprise further structural elements which are incorporated by using comonomers or reactive additives as further starting materials in the reaction.
Preferably, at least 80 %, more preferably at least 90%, even more preferably at least 95% by weight of the starting materials used for the preparation of the resin are R²-C₆H₄-OH and acetylene.
In a most preferred embodiment essentially no other starting materials than R²-C₆H₄-OH and acetylene are used for the preparation of the resin.
Preferably the number average and weight average molecular weights Mn and Mw of components (A) are Mn from 500 to 2000 and Mw from 750 to 4100 g/mol.
Furthermore, the presence of terminal vinylidene groups of formula (III) can be proven by infrared spectroscopy or iodine number according to EN 14111:2003. Typical are absorption bands at wavenumbers of 985 cm^-1 and/or 900 cm^-1, each approximately ± 20 cm^-1.
In a preferred embodiment the content of ingredients in component (A) being insoluble in cyclohexane at 20 °C is less than 1 wt%, preferably not more than 0.75 wt%, more preferably not more than 0.5 wt% and most preferably not more than 0.25 wt%.
The solubility of component (A) in cyclohexane at 20 °C is usually at least 45% by weight, preferably at least 50%, more preferably at least 55%, and most preferably at least 60% by weight (measured after initial stirring and heating to 70 °C in a closed container and cooling down to 20 °C).
In another preferred embodiment the content of metals in component (A) is not more than 100 ppm by weight, preferably not more than 50 ppm by weight, more preferably not more than 25 ppm by weight, most preferably not more than 15 ppm by weight, and especially not more than 10 ppm by weight, calculated for each metal species.
Sources of metals in component (A) are usually catalysts used or basic solutions of (earth) alkaline bases used during work up procedures. Metals are detrimental in fuels since they may lead to deposits in engines, such as combustion spaces, injectors or valves, or fuel pipes.
Component (A) is added to the middle distillate fuel or diesel fuel in a total amount of preferably 1 to 1000 ppm by weight, more preferably of 2 to 500 ppm by weight, even more preferably of 3 to 350 ppm by weight and especially of 4 to 250 ppm by weight, for example of 5 to 100 ppm by weight.

Component (B)

Component (B) is at least one cold flow improver which is selected from the group consisting of compounds (B1) to (B6) listed below.
Suitable cold flow improvers are in principle all organic compounds which are capable of improving the flow performance of middle distillate fuels or diesel fuels under cold conditions. For the intended purpose, they must have sufficient oil solubility. More particularly, useful cold flow improvers for this purpose are the cold flow improvers (middle distillate flow improvers, MDFIs) typically used in the case of middle distillates of fossil origin, i.e. in the case of customary mineral diesel fuels. However, it is also possible to use organic compounds which partly or predominantly have the properties of a wax antisettling additive ("WASA") when used in customary diesel fuels. They can also act partly or predominantly as nucleators. It is also possible to use mixtures of organic compounds effective as MDFIs and/or effective as WASAs and/or effective as nucleators.
The cold flow improver is selected from:

(B1) copolymers of a C₂- to C₄₀-olefin with at least one further ethylenically unsaturated monomer;
(B2) comb polymers;
(B3) polyoxyalkylenes;
(B4) polar nitrogen compounds;
(B5) sulfocarboxylic acids or sulfonic acids or derivatives thereof; and
(B6) poly(meth)acrylic esters.

It is possible to use either mixtures of different representatives from one of the particular classes (B1) to (B6) or mixtures of representatives from different classes (B1) to (B6).
Among the classes compounds (B1) and/or (B4) are preferred, especially compounds (B4).
Suitable C₂- to C₄₀-olefin monomers for the copolymers of class (B1) are, for example, those having 2 to 20 and especially 2 to 10 carbon atoms, and 1 to 3 and preferably 1 or 2 carbon-carbon double bonds, especially having one carbon-carbon double bond. In the latter case, the carbon-carbon double bond may be arranged either terminally (a-olefins) or internally. However, preference is given to α-olefins, particular preference to α-olefins having 2 to 6 carbon atoms, for example propene, 1-butene, 1-pentene, 1-hexene and in particular ethylene.
In the copolymers of class (B1), the at least one further ethylenically unsaturated monomer is preferably selected from alkenyl carboxylates, (meth)acrylic esters and further olefins.
When further olefins are also copolymerized, they are preferably higher in molecular weight than the abovementioned C₂- to C₄₀-olefin base monomers. When, for example, the olefin base monomer used is ethylene or propene, suitable further olefins are especially C₁₀- to C₄₀-α-olefins. Further olefins are in most cases only additionally copolymerized when monomers with carboxylic ester functions are also used.
Suitable (meth)acrylic esters are, for example, esters of (meth)acrylic acid with C₁- to C₂₀-alkanols, especially C₁- to C₁₀-alkanols, in particular with methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, isobutanol, tert-butanol, pentanol, hexanol, heptanol, octanol, 2-ethylhexanol, nonanol and decanol, and structural isomers thereof.
Suitable alkenyl carboxylates are, for example, C₂- to C₁₄-alkenyl esters, for example the vinyl and propenyl esters, of carboxylic acids having 2 to 21 carbon atoms, whose hydrocarbyl radical may be linear or branched. Among these, preference is given to the vinyl esters. Among the carboxylic acids with a branched hydrocarbyl radical, preference is given to those whose branch is in the α position to the carboxyl group, and the α-carbon atom is more preferably tertiary, i.e. the carboxylic acid is what is called a neocarboxylic acid. However, the hydrocarbyl radical of the carboxylic acid is preferably linear.
Examples of suitable alkenyl carboxylates are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl neopentanoate, vinyl hexanoate, vinyl neononanoate, vinyl neodecanoate and the corresponding propenyl esters, preference being given to the vinyl esters. A particularly preferred alkenyl carboxylate is vinyl acetate; typical copolymers of group (B1) resulting therefrom are ethylene-vinyl acetate copolymers ("EVAs"), which are some of the most frequently used.
Ethylene-vinyl acetate copolymers usable particularly advantageously and the preparation thereof are described in WO 99/29748 .
Suitable copolymers of class (B1) are also those which comprise two or more different alkenyl carboxylates in copolymerized form, which differ in the alkenyl function and/or in the carboxylic acid group. Likewise suitable are copolymers which, as well as the alkenyl carboxylate(s), comprise at least one olefin and/or at least one (meth)acrylic ester in copolymerized form.
Terpolymers of a C₂- to C₄₀-α-olefin, a C₁- to C₂₀-alkyl ester of an ethylenically unsaturated monocarboxylic acid having 3 to 15 carbon atoms and a C₂- to C₁₄-alkenyl ester of a saturated monocarboxylic acid having 2 to 21 carbon atoms are also suitable as copolymers of class (B1). Terpolymers of this kind are described in WO 2005/054314 . A typical terpolymer of this kind is formed from ethylene, 2-ethylhexyl acrylate or 2-propylheptyl acrylate and vinyl acetate.
The at least one or the further ethylenically unsaturated monomer(s) are copolymerized in the copolymers of class (B1) in an amount of preferably 1 to 50% by weight, especially 10 to 45% by weight and in particular 20 to 40% by weight, based on the overall copolymer. The main proportion in terms of weight of the monomer units in the copolymers of class (B1) therefore originates generally from the C₂- to C₄₀ base olefins.
The copolymers of class (B1) preferably have a number-average molecular weight Mn of 1000 to 20 000, more preferably of 1000 to 10 000 and especially of 1000 to 8000.
Typical comb polymers of component (B2) are, for example, obtainable by the copolymerization of maleic anhydride or fumaric acid with another ethylenically unsaturated monomer, for example with an α-olefin or an unsaturated ester, such as vinyl acetate, and subsequent esterification of the anhydride or acid function with an alcohol having at least 10 carbon atoms. Further suitable comb polymers are copolymers of α-olefins and esterified comonomers, for example esterified copolymers of styrene and maleic anhydride or esterified copolymers of styrene and fumaric acid. Suitable comb polymers may also be polyfumarates or polymaleates. Homo- and copolymers of vinyl ethers are also suitable comb polymers. Comb polymers suitable as components of class (B2) are, for example, also those described in WO 2004/035715 and in "Comb-Like Polymers, Structure and Properties", N. A. Plate and V. P. Shibaev, J. Poly. Sci. Macromolecular Revs. 8, pages 117 to 253 (1974). Mixtures of comb polymers are also suitable.
Polyoxyalkylenes suitable as components of class (B3) are, for example, polyoxyalkylene esters, polyoxyalkylene ethers, mixed polyoxyalkylene ester/ethers and mixtures thereof. These polyoxyalkylene compounds preferably comprise at least one linear alkyl group, preferably at least two linear alkyl groups, each having 10 to 30 carbon atoms and a polyoxyalkylene group having a number-average molecular weight of up to 5000. Such polyoxyalkylene compounds are described, for example, in EP-A 061 895 and also in US 4 491 455 . Particular polyoxyalkylene compounds are based on polyethylene glycols and polypropylene glycols having a number-average molecular weight of 100 to 5000. Additionally suitable are polyoxyalkylene mono- and diesters of fatty acids having 10 to 30 carbon atoms, such as stearic acid or behenic acid.
Polar nitrogen compounds suitable as components of class (B4) may be either ionic or nonionic and preferably have at least one substituent, especially at least two substituents, in the form of a tertiary nitrogen atom of the general formula >NR⁷ in which R⁷ is a C₈- to C₄₀-hydrocarbyl radical. The nitrogen substituents may also be quaternized, i.e. be in cationic form. Examples of such nitrogen compounds are ammonium salts and/or amides which are obtainable by the reaction of at least one amine substituted by at least one hydrocarbyl radical with a carboxylic acid having 1 to 4 carboxyl groups or with a suitable derivative thereof. The amines preferably comprise at least one linear C₈- to C₄₀-alkyl radical. Primary amines suitable for preparing the polar nitrogen compounds mentioned are, for example, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tetradecylamine and the higher linear homologs; secondary amines suitable for this purpose are, for example, dioctadecylamine and methylbehenylamine. Also suitable for this purpose are amine mixtures, especially amine mixtures obtainable on the industrial scale, such as fatty amines or hydrogenated tallamines, as described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 6th Edition, "Amines, aliphatic" chapter. Acids suitable for the reaction are, for example, cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, naphthalenedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and succinic acids substituted by long-chain hydrocarbyl radicals.
More particularly, the component of class (B4) is an oil-soluble reaction product of poly(C₂- to C₂₀-carboxylic acids) having at least one tertiary amino group with primary or secondary amines. The poly(C₂- to C₂₀-carboxylic acids) which have at least one tertiary amino group and form the basis of this reaction product comprise preferably at least 3 carboxyl groups, especially 3 to 12 and in particular 3 to 5 carboxyl groups. The carboxylic acid units in the polycarboxylic acids have preferably 2 to 10 carbon atoms, and are especially acetic acid units. The carboxylic acid units are suitably bonded to the polycarboxylic acids, usually via one or more carbon and/or nitrogen atoms. They are preferably attached to tertiary nitrogen atoms which, in the case of a plurality of nitrogen atoms, are bonded via hydrocarbon chains.
The component of class (B4) is preferably an oil-soluble reaction product based on poly(C₂- to C₂₀-carboxylic acids) which have at least one tertiary amino group and are of the general formula (IVa) or IVb

in which the variable A is a straight-chain or branched C₂- to C₆-alkylene group or the moiety of the formula (V)
and the variable B is a C₁- to C₁₉-alkylene group. The compounds of the general formulae (IVa) and (IVb) especially have the properties of a WASA.
Moreover, the preferred oil-soluble reaction product of component (B4), especially that of the general formula (IVa) or IVb, is an amide, an amide-ammonium salt or an ammonium salt in which no, one or more carboxylic acid groups have been converted to amide groups.
Straight-chain or branched C₂- to C₆-alkylene groups of the variable A are, for example, 1,1-ethylene, 1,2-propylene, 1,3-propylene, 1,2-butylene, 1,3-butylene, 1,4-butylene, 2-methyl-1,3-propylene, 1,5-pentylene, 2-methyl-1,4-butylene, 2,2-dimethyl-1,3-propylene, 1,6-hexylene (hexamethylene) and especially 1,2-ethylene. The variable A comprises preferably 2 to 4 and especially 2 or 3 carbon atoms.
C₁- to C₁₉-alkylene groups of the variable B are, for example, methylene, 1,2-ethylene, 1,3-propylene, 1,4-butylene, hexamethylene, octamethylene, decamethylene, dodecamethylene, tetradecamethylene, hexadecamethylene, octadecamethylene, nonadecamethylene and especially methylene. The variable B comprises preferably 1 to 10 and especially 1 to 4 carbon atoms.
The primary and secondary amines as a reaction partner for the polycarboxylic acids to form component (B4) are typically monoamines, especially aliphatic monoamines. These primary and secondary amines may be selected from a multitude of amines which bear hydrocarbyl radicals which may optionally be bonded to one another.
These parent amines of the oil-soluble reaction products of component (B4) are usually secondary amines and have the general formula HN(R⁸)₂ in which the two variables R⁸ are each independently straight-chain or branched C₁₀- to C₃₀-alkyl radicals, especially C₁₄- to C₂₄-alkyl radicals. These relatively long-chain alkyl radicals are preferably straight-chain or only slightly branched. In general, the secondary amines mentioned, with regard to their relatively long-chain alkyl radicals, derive from naturally occurring fatty acids and from derivatives thereof. The two R⁸ radicals are preferably identical.
The secondary amines mentioned may be bonded to the polycarboxylic acids by means of amide structures or in the form of the ammonium salts; it is also possible for only a portion to be present as amide structures and another portion as ammonium salts. Preferably only few, if any, free acid groups are present. The oil-soluble reaction products of component (B4) are preferably present completely in the form of the amide structures.
Typical examples of such components (B4) are reaction products of nitrilotriacetic acid, of ethylenediaminetetraacetic acid or of propylene-1,2-diaminetetraacetic acid with in each case 0.5 to 1.5 mol per carboxyl group, especially 0.8 to 1.2 mol per carboxyl group, of a di-C₁₀- to C₂₄-alkyl amine, preferably dioleylamine, dipalmitamine, dicocoamine, distearylamine, dibehenylamine or especially ditallamine. A particularly preferred component (B4) is the reaction product of 1 mol of ethylenediaminetetraacetic acid and 4 mol of hydrogenated ditallamine.
Further typical examples of component (B4) include the N,N-dialkylammonium salts of 2-N',N'-dialkylamidobenzoates, for example the reaction product of 1 mol of phthalic anhydride and 2 mol of ditallamine, the latter being hydrogenated or unhydrogenated, and the reaction product of 1 mol of an alkenylspirobislactone with 2 mol of a dialkylamine, for example ditallamine and/or tallamine, the latter two being hydrogenated or unhydrogenated.
Further typical structure types for the component of class (B4) are cyclic compounds with tertiary amino groups or condensates of long-chain primary or secondary amines with carboxylic acid-containing polymers, as described in WO 93/18115 .
Further preferred examples of polar nitrogen-containing compounds are copolymers of alphaolefins with maleic anhydride and optionally further comonomers which are further reacted with primary or secondary amines.
In one embodiment the polar nitrogen-containing compounds are copolymers of C₁₀- to C₂₀-alpha-olefins with maleic anhydride which are further reacted with primary or secondary C₈-C₁₆-alkyl amines which are bound via amide- and/or imide-groups. Examples are disclosed in EP 1526167 A designated as component B), especially those in Table 4 thereof, or in EP 1857529 designated as component B) which are incorporated by reference.
Further preferred copolymers are disclosed in WO 16/83130 which are incorporated by reference as copolymers of unsaturated dicarboxylic acids, C₆- to C₂₀-alpha olefins, C₆- to C₂₀-alkylesters of acrylic acid or methacrylic acid, and optionally further copolymerizable monomers which are further reacted with dialkylamines bearing C₁₇- to C₃₀-alkyl groups. Especially preferred are Examples 1 to 10 in Table A of WO 16/83130 .
Further polar nitrogen-containing compounds are reaction products of phthalic anhydride with amines, especially dialkylamines, as described in US 4211534 .
Sulfocarboxylic acids, sulfonic acids or derivatives thereof which are suitable as cold flow improvers of the component of class (B5) are, for example, the oil-soluble carboxamides and carboxylic esters of ortho-sulfobenzoic acid, in which the sulfonic acid function is present as a sulfonate with alkyl-substituted ammonium cations, as described in EP-A 261 957 .
Poly(meth)acrylic esters suitable as cold flow improvers of the component of class (B6) are either homo- or copolymers of acrylic and methacrylic esters. Preference is given to copolymers of at least two different (meth)acrylic esters which differ with regard to the esterified alcohol. The copolymer optionally comprises another different olefinically unsaturated monomer in copolymerized form. The weight-average molecular weight of the polymer is preferably 50 000 to 500 000. A particularly preferred polymer is a copolymer of methacrylic acid and methacrylic esters of saturated C₁₄- and C₁₅-alcohols, the acid groups having been neutralized with hydrogenated tallamine. Suitable poly(meth)acrylic esters are described, for example, in WO 00/44857 .
The inventive mixtures can preferably be used in fuels in their function as a paraffin dispersant ("WASA"). The inventive mixtures often display their action as a paraffin dispersant particularly well only once together with the flow improvers.
In the context of present invention, flow improvers shall be understood to mean all additives which improve the cold properties of middle distillate fuels. As well as the actual cold flow improvers ("MDFI"), these are also nucleators (cf. also Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, volume A16, p. 719 ff.).
Cold flow improvers of this kind are described, for example, in WO 2007/147753 , particularly at page 13 line 1 to page 16, line 32 therein, which is hereby incorporated into the present disclosure by reference.
The inventive middle distillate fuels comprise these, in addition to component (A), in an amount of typically 1 to 2000 ppm by weight, preferably of 5 to 1000 ppm by weight, especially of 10 to 750 ppm by weight and in particular of 50 to 500 ppm by weight, for example of 150 to 400 ppm by weight.

Fuels

It is likewise possible, through the use of the inventive mixtures, to improve a number of further fuel properties. Mention shall be made here by way of example merely of the additional effect as a cloud point depressant (CPD) or as a booster together with a flow improver for further improvement of the CFPP.
The inventive mixtures can be added either to middle distillate fuels entirely of fossil origin, i.e. those that have been obtained from mineral oil, or to fuels which, as well as the proportion based on mineral oil, comprise a proportion of biodiesel, in order to improve the properties thereof. In both cases, a distinct improvement in the cold flow characteristics of the middle distillate fuel is observed, i.e. a lowering of the PP and/or CP values and/or CFPP values, irrespective of the origin or the composition of the fuel. The paraffin crystals which precipitate out are effectively kept suspended, and so there are no blockages of filters and lines by sedimented paraffin. The inventive mixtures have a good activity spectrum and thus achieve very good dispersion of the paraffin crystals which precipitate out in a wide variety of different middle distillate fuels.
The present invention also provides fuels, especially those with a biodiesel content, comprising the inventive mixtures.
In general, the fuels or fuel additive concentrates also comprise, as further additives in amounts customary therefor, flow improvers (as described above), further paraffin dispersants, conductivity improvers, anticorrosion additives, lubricity additives, antioxidants, metal deactivators, antifoams, demulsifiers, detergents, cetane number improvers, solvents or diluents, dyes or fragrances or mixtures thereof. The aforementioned further additives are familiar to those skilled in the art and therefore need not be explained any further here.
In the context of the present invention, fuel oils shall be understood to mean middle distillate fuels of fossil, vegetable or animal origin, biofuel oils ("biodiesel") and mixtures of such middle distillate fuels and biofuel oils.
Middle distillate fuels (also called "middle distillates" for short hereinafter) are especially understood to mean fuels which are obtained by distilling crude oil as the first process step and boil within the range from 120 to 450°C. Such middle distillate fuels are used especially as diesel fuel, heating oil or kerosene, particular preference being given to diesel fuel and heating oil. Preference is given to using low-sulfur middle distillates, i.e. those which comprise less than 350 ppm of sulfur, especially less than 200 ppm of sulfur, in particular less than 50 ppm of sulfur. In special cases they comprise less than 10 ppm of sulfur; these middle distillates are also referred to as "sulfur-free". They are generally crude oil distillates which have been subjected to refining under hydrogenating conditions and therefore comprise only small proportions of polyaromatic and polar compounds. They are preferably those middle distillates which have 90% distillation points below 370°C, especially below 360°C and in special cases below 330°C.
Low-sulfur and sulfur-free middle distillates may also be obtained from relatively heavy mineral oil fractions which cannot be distilled under atmospheric pressure. Typical conversion processes for preparing middle distillates from heavy crude oil fractions include: hydrocracking, thermal cracking, catalytic cracking, coking processes and/or visbreaking. Depending on the process, these middle distillates are obtained in low-sulfur or sulfur-free form, or are subjected to refining under hydrogenating conditions.
The middle distillates preferably have aromatics contents of below 35% by weight, preferably below 33% by weight, and especially below 30% by weight. The content of normal paraffins is between 5% by weight and 50% by weight, preferably between 10 and 35% by weight.
In a preferred embodiment the aromatics content of the middle distillates is more than 20% by weight, preferably more than 21%, more preferably at least 22% and most preferably at least 23% by weight.
In the context of the present invention, middle distillate fuels shall also be understood here to mean those fuels which can either be derived indirectly from fossil sources such as mineral oil or natural gas, or else are produced from biomass via gasification and subsequent hydrogenation. A typical example of a middle distillate fuel which is derived indirectly from fossil sources is the GTL ("gas-to-liquid") diesel fuel obtained by means of Fischer-Tropsch synthesis. A middle distillate is prepared from biomass, for example, via the BTL ("biomass-to-liquid") process, and can be used as fuel either alone or in a mixture with other middle distillates. The middle distillates also include hydrocarbons which are obtained by the hydrogenation of fats and fatty oils. They comprise predominantly n-paraffins.
The qualities of the heating oils and diesel fuels are laid down in more detail, for example, in DIN 51603 and EN 590 (cf. also Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, volume A12, p. 617 ff.).
In addition to its use in the middle distillate fuels of fossil, vegetable or animal origin mentioned, which are essentially hydrocarbon mixtures, the inventive copolymer can also be used in biofuel oils and in mixtures of the middle distillates mentioned with biofuel oils, in order to improve cold flow characteristics. Mixtures of this kind are commercially available and usually comprise the biofuel oils in minor amounts, typically in amounts of 1% to 30% by weight, especially of 3% to 10% by weight, based on the total amount of middle distillate of fossil, vegetable or animal origin and biofuel oil.
Biofuel oils are generally based on fatty acid esters, preferably essentially on alkyl esters of fatty acids which derive from vegetable and/or animal oils and/or fats. Alkyl esters are preferably understood to mean lower alkyl esters, especially C₁- to C₄-alkyl esters, which are obtainable by transesterifying the glycerides which occur in vegetable and/or animal oils and/or fats, especially triglycerides, by means of lower alcohols, for example ethanol or in particular methanol ("FAME"). Typical lower alkyl esters which are based on vegetable and/or animal oils and/or fats and find use as a biofuel oil or components thereof are, for example, HVO (hydrogenated vegetable oil), sunflower methyl ester, palm oil methyl ester ("PME"), soya oil methyl ester ("SME") and especially rapeseed oil methyl ester ("RME").
The inventive copolymer brings about a reduction in the crystallization of paraffin crystals in fuels, especially those which comprise biofuel oils.
The other further additives mentioned above are, incidentally, familiar to those skilled in the art and therefore need not be elucidated here any further.
The examples which follow are intended to elucidate the present invention without restricting it.

Examples

Synthetic Examples of Components (A)

Example 1 (inventive)

A resin was prepared from p-tert-butylphenol and acetylene analogous to the experimental procedure as described in A. O. Zoss et al., Industrial and Engineering Chemistry, 41, 1949, 73 - 77.
The resin obtained has a molecular weight of Mn = 1269, Mw 1941 g/mol and iodine number according to according to EN 14111:2003 of 85 g I₂/100 g. The resin was used as a solution of 40 wt% in Solvesso 150.

Example 2 (comparative)

A resin Technic TR140 from Techno WaxChem Pvt. Ltd, Kolkata - 700046, India, according to the manufacturer based upon p-tert-butylphenol and formaldehyde was used. Molecular weights were determined to be Mn 1200 and Mw 1793.

Example 3 (comparative)

A resin Technic KR140 from Techno WaxChem Pvt. Ltd, Kolkata - 700046, India, according to the manufacturer based upon p-tert-butylphenol and acetaldehyde was used. Molecular weights were determined to be Mn 1431 and Mw 2643.

Use examples

In the use examples, diesel fuels (DF) having the details of origin and indices reported in Table A were used.

Efficacy as paraffin dispersants (WASAs)

In the examples which follow (Table B), the mixtures prepared above were examined for their efficacy as paraffin dispersants (WASAs) in the presence of customary flow improvers (MDFIs).
The cloud point (CP) to ISO 3015 and the CFPP to EN 116 of the additized fuel samples were determined. Thereafter, the additized fuel samples in 500 ml glass cylinders, in order to determine the delta CP, were cooled to -16°C in a cold bath and stored at this temperature for 16 hours. For each sample, the CP was again determined to ISO 3015 on the 20% by volume base phase separated off at -16°C. The smaller the deviation of the CP of the 20% by volume base phase from the original CP (delta CP) for the respective fuel sample, the better the dispersion of the paraffins.

The smaller the delta CP and the lower the CFPP, the better the cold flow characteristics of a diesel fuel.

Table A - Fuels

Fuel	Origin	Cloud Point CP [°C]	CFPP [°C]	Density @15°C [kg/m3]	90 Vol% - 20 Vol% [°C]	IBP [°C]	FBP [°C]	n-Paraffine [%]
DF1	Eastern Europe	-7.2	-8	835.1	103	179.4	354.4	18.02
DF2	Eastern Europe	-7.5	-9	836	82	192.5	351.9	22.41
DF3	Eastern Europe	-3.7	-6	839.9	93	183.5	364.4	17.37

Table B - Use Examples

Fuel	Wax AntiSettling Flow Improver (WAFI)	ratio	component (A)	amount [ppm]	CFPP Orginal	CFPP bottom	Delta CFPP
DF1	WAFI1		without		-23	-21	2.5
	WAFI1	70/30	Example 2	600	-18	-19	1.9
	WAFI1	70/30	Example 3	600	-22	-21	1.1
DF2	WAFI2		without		-27	-25	3.8
	WAFI2	60/40	Example 1	500	-26	-26	2.0
	WAFI2	60/40	Example 2	500	-26	-20	3.8
		60/40	Example 3	500	-28	-28	2.1
DF3	WAFI3		without		-25	-26	0.4
	WAFI3	70/30	Example 1	600	-26	-26	0.3
	WAFI3	70/30	Example 2	400	-26	-27	0.7
	WAFI3	70/30	Example 3	400	-27	-25	0.5

WAFI1 comprises a mixture of an ethylene - vinyl acetate copolymer (Mn = 3350 g/mol), an ethylene - vinyl acetate - 2-ethylhexyl acrylate terpolymer (Mn = 3200 g/mol), the reaction product of ethylenediaminetetraacetic acid and distearylamine, and the reaction product of tridecylamine and maleic anhydride
WAFI2 comprises comprises a mixture of an ethylene - vinyl acetate copolymer (Mn = 2450 g/mol), an ethylene - vinyl acetate - 2-ethylhexyl acrylate terpolymer (Mn = 3200 g/mol), the reaction product of ethylenediaminetetraacetic acid and distearylamine, and the reaction product of tridecylamine and maleic anhydride
WAFI3 comprises comprises a mixture of an ethylene - vinyl acetate - 2-ethylhexyl acrylate terpolymer (Mn = 3200 g/mol), the reaction product of ethylenediaminetetraacetic acid and distearylamine, and the reaction product of tridecylamine and maleic anhydride

It can easily be seen that component (A) based upon acetaldehyde (Example 3) yields better (i.e. lower) delta CP values than component (A) based upon formaldehyde (Example 2).
The tests in fuels DF2 and DF3 further show that component (A) based upon Example 1 according to the invention yields a better delta CP value than based upon Example 3 with a similar structure.

Claims

Mixtures of
(A) reaction products of acetylene and p-alkylphenols with

(B) at least one cold flow improver selected from the group consisting of
(B1) copolymers of a C₂- to C₄₀-olefin with at least one further ethylenically unsaturated monomer;

(B2) comb polymers;

(B3) polyoxyalkylenes;

(B4) polar nitrogen compounds;

(B5) sulfocarboxylic acids or sulfonic acids or derivatives thereof; and

(B6) poly(meth)acrylic esters.
Mixtures according to Claim 1, wherein component (A) comprises repeating units of formula (I)
wherein,
R² is a linear or branched, saturated or unsaturated aliphatic hydrocarbon group with 2 to 100 carbon atoms.
Mixtures according to Claim 1 or 2, wherein component (A) comprises units of formula (II)
and/or terminal groups of formula (III)
wherein
R² is a linear or branched, saturated or unsaturated aliphatic hydrocarbon group with 2 to 100 carbon atoms.
Mixtures according to any of Claims 2 or 3, wherein R² is a linear or branched, saturated aliphatic hydrocarbon group with 3 to 20, more preferably from 4 to 16 carbon atoms.
Mixtures according to any of Claims 2 or 3, wherein R² is selected from the group consisting of ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and tert-butyl, n-pentyl, tert-pentyl, n-hexyl, 2-ethylhexyl, 2-propylheptyl, n-octyl, iso-octyl, n-nonyl, iso-nonyl, n-decyl, iso-decyl, n-undecyl, iso-undecyl, n-dodecyl, iso-dodecyl, n-tridecyl, iso-tridecyl, n-tetradecyl, iso-tetradecyl, n-hexadecyl, iso-hexadecyl, n-octadecyl, iso-octadecyl, and eicosyl.
Mixtures according to any of the preceding claims, wherein component (B) is selected from the groups copolymers of a C₂- to C₄₀-olefin with at least one further ethylenically unsaturated monomer (B1) and polar nitrogen compounds (B4).
Mixtures according to any of the preceding claims, wherein component (B) is a reaction product of nitrilotriacetic acid, of ethylenediaminetetraacetic acid or of propylene-1,2-diaminetetraacetic acid with in each case 0.5 to 1.5 mol per carboxyl group of a di-C₁₀- to C24-alkyl amine.
Mixtures according to Claim 7, wherein the di-C₁₀- to C₂₄-alkyl amine is selected from the group consisting of dioleylamine, dipalmitamine, dicocoamine, distearylamine, dibehenylamine, and ditallamine.
Mixtures according to any of the claims 1 to 6, wherein component (B) is an ethylene-alkenyl carboxylate copolymer (B1).
Mixtures according to Claim 9, wherein component (B) is an ethylene-vinyl acetate copolymer (B1).
Mixtures according to any of the claims 1 to 6, wherein component (B) is a terpolymer of a C₂- to C₄₀-α-olefin, a C₁- to C₂₀-alkyl ester of an ethylenically unsaturated monocarboxylic acid having 3 to 15 carbon atoms and a C₂- to C₁₄-alkenyl ester of a saturated monocarboxylic acid having 2 to 21 carbon atoms (B1).
Mixtures according to Claim 11, wherein the C₁- to C₂₀-alkyl ester of an ethylenically unsaturated monocarboxylic acid having 3 to 15 carbon atoms is 2-ethylhexyl acrylate or 2-propylheptyl acrylate.
Use the mixtures according to any of the preceding claims for reducing crystallization of paraffin crystals in fuels and/or improving the cold flow properties of fuels.
Middle distillate fuels comprising a mixture of any of claims 1 to 12.
Middle distillate fuel according to Claim 14, wherein the middle distillate fuel is a biofuel oil.