US20090307964A1

US20090307964A1 - Use of solubilizers for homogenizing additive concentrates

Info

Publication number: US20090307964A1
Application number: US12/482,059
Authority: US
Inventors: Frank-Olaf Maehling; Irene Troetsch-Schaller; Heinrich LUBOJANSKI; Thomas Pfeiffer
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2008-06-12
Filing date: 2009-06-10
Publication date: 2009-12-17
Also published as: WO2009150145A1

Abstract

A cold-stabilized fuel oil composition comprising a major proportion by weight of a middle distillate fuel which boils in the range of 120-500° C. and minor proportions by weight of

- (A) at least one cold flow improver,
- (B) at least one detergent additive and
- (C) at least one cold solubilizer I

- which has at least one radical having at least 4 carbon atoms.

Description

The present invention relates to the use of specific dicarboxylic acid derivatives as solubilizers for homogenizing additive concentrates which comprise cold flow improvers, detergent additives, inert organic solvents and if appropriate cetane number improvers. The invention further relates to additive concentrates suitable for additizing fuel oil compositions which consist predominantly of a middle distillate fuel which boils in the range of 120-500° C. and/or a renewable fuel, said additive concentrates having the ingredients mentioned.
In the formulation or storage of additive concentrates which, as well as cold flow improvers which are typically added to the diesel fuels and heating oils in the mineral oil refineries, also comprise detergent additives and cetane number improvers which form the main constituents of so-called diesel performance packages, there are frequent occurrences - especially at temperatures significantly below 20° C.—of flaky precipitates which cannot be filtered off; attempted filtration can lead to filter conglutination. At least, such additive concentrates are, however, generally slightly to highly turbid. The presence of additionally used organic solvents in the additive concentrates cannot prevent such flaky precipitates or turbidities. The flaky precipitates, which usually at first remain more or less dispersed in the solution, can subsequently lead to severe sedimentation or to gel formation in the additive concentrate.
It was therefore an object of the present invention to stabilize such additive concentrates which comprise both cold flow improvers and detergent additives, and also inert organic solvents and if appropriate cetane number improvers, such that the flaky precipitates or turbidities described do not occur in the course of formulation and storage of the additive concentrates.
Accordingly, the use has been found of at least one solubilizer of the general formula I
in which

- R¹denotes a hydrocarbylene radical having from 1 to 12 carbon atoms or a hydrocarbylene radical which has from 2 to 12 carbon atoms, is interrupted by one or more heteroatoms selected from the group of O, S and N, and may in each case bear one or more functional groups selected from the group of OH, OR³, NH₂, NHR⁴, NR⁴R⁵, COOH, COOR⁷, CONHR⁴and CONR⁴R⁵, where amino groups may also be present in protonated form and carboxylic acid groups also in deprotonated form,
- X is OH, OR³, NH₂, NHR⁴or NR⁴R⁵, where, in the case that X together with the adjacent carbonyl group is a carboxylic acid radical, this radical is present in deprotonated form and the accompanying cation may be a hydrocarbyl-substituted ammonium cation selected from the group of [H₃NR⁸]⁺, [H₂NR⁸R⁹]⁺ and [HNR⁸R⁹R¹⁰]⁺,
- Y is O, S, NH or NR⁶, or, in the case that X is NH₂or NHR⁴, is a chemical bond to X with formation of an imide structure,
  where R²to R¹⁰are each independently hydrocarbyl radicals having from 1 to 30 carbon atoms,

with the proviso that at least one of the R², R³, R⁴, R⁵, R⁶and R⁷radicals has at least 4 carbon atoms,
for homogenizing additive concentrates suitable for additizing fuel oil compositions which consist predominantly of a middle distillate fuel which boils in the range of 120-500° C. and/or a renewable fuel, said additive concentrates comprising

(A) at least one cold flow improver,
(B) at least one detergent additive and
(C) an inert organic solvent or a mixture of such solvents.

The additive concentrates mentioned preferably additionally comprise

(D) at least one cetane number improver.

However, the action of the solubilizers I used according to the invention also occurs in principle in additive concentrates which do not comprise any cetane number improver.
In a preferred embodiment, the solubilizers I used in accordance with the invention are used to homogenize additive concentrates which comprise

- (A) from 1 to 50% by weight, especially from 2 to 40% by weight, in particular from 3 to 20% by weight, of at least one cold flow improver,
- (B) from 0.5 to 40% by weight, preferably from 0.7 to 20% by weight, especially from 1 to 12% by weight, in particular from 1.5 to 7% by weight, of at least one detergent additive,
- (C) from 1 to 60% by weight, especially from 3 to 50% by weight, in particular from 5 to 40% by weight, of an inert organic solvent or of a mixture of such solvents and
- (D) from 0 to 80% by weight, especially from 25 to 75% by weight, in particular from 40 to 70% by weight, of at least one cetane number improver.

The additive concentrates mentioned may additionally comprise further ingredients, in which case the sum of all ingredients adds up to 100% by weight.
In the context of the present invention, homogenization shall be understood to mean the prevention or the elimination of the flaky precipitates or turbidities described above in the additive concentrates.
The specific dicarboxylic acid derivatives of the general formula I used as solubilizers in the present invention are known from WO 2007/131894. They are recommended there as cold stabilization enhancers in fuel oil compositions which comprise customary cold flow improvers and detergent additives, in low dosages—specifically from 1 to 2000 ppm by weight, based on the fuel oil composition. Corresponding additive concentrates or technical problems to be solved with such additive concentrates are not addressed in WO 2007/131894.
EP-A 807 676 discloses low-sulfur middle distillate fuels which, to improve their lubricity, comprise carboxamides, for example also amides of C₃- to C₄₀-dicarboxylic acids, cold flow improvers and ashless dispersants. The additives mentioned may also be added to the middle distillate fuels in the form of a concentrate which typically also comprises diluents or solvents.
Compounds of the type of the general formula I mentioned are also known as gasoline fuel additives. For instance, EP-A 301 448 describes alkali metal or alkaline earth metal salts of amides of di-, tri- or tetracarboxylic acids, for example monoamides of dicarboxylic acids such as maleic acid, as valve seat wear-reducing additives for gasoline fuels. Similarly, EP-A 555 006 discloses the wear-reducing action of dicarboxylic acid derivatives such as the reaction product of maleic anhydride with a secondary amine to give the monoamide in the form of the alkali metal salt in internal combustion engines operated with gasoline fuel.
EP-A 798 364 describes amides obtained by condensation reactions of carboxylic acids with aliphatic amines as additives for diesel fuels for reducing deposits at the injection nozzles, for increasing the lubricity of the fuel and for reducing the wear of the injection pumps. These amides are based preferably on relatively long-chain mono-carboxylic acids, especially having from 8 to 30 carbon atoms, such as oleic acid, and on relatively long-chain amines, especially those having from 8 to 20 carbon atoms, such as oleylamine or oleylpropylenediamine. However, dodecenylsuccinic acid and its anhydride are also mentioned as a starting material for such amides. The amides mentioned may be used together with other customary diesel additives such as low-temperature flow improvers, cetane number improvers, antioxidants, metal deactivators, rust and corrosion inhibitors, demulsifiers and foam inhibitors.
The compounds of the general formula I are dicarboxylic acid derivatives. Depending on the definition of the variables X and Y, they are present especially in the form of monoesters, monothioesters, monoamides, diesters, bisthioesters, diamides or mixed derivatives having in each case two different functions from the group of the ester, thioester and amide functions or are joined to form a cycle via an imide function.
The variable R¹in the compounds I is the bridging member between the two carbonyl carbon atoms. A hydrocarbylene radical shall be understood here to mean a divalent hydrocarbon radical of any structure which, however, in accordance with the definition, may also comprise heteroatoms and/or functional groups. The hydrocarbenyl radical may be saturated, unsaturated or of aromatic nature; it may have a linear, branched or cyclic structure.
R¹preferably denotes a linear or branched alkylene group having from 1 to 12, especially from 2 to 8, in particular from 2 to 6 carbon atoms, for example methylene, 1,1-ethylene, 1,2-ethylene, 1,3-propylene, 1,2-propylene, 1,2-butylene, 1,2-hexylene, 1,2-octylene, 1,2-decylene, 1,2-dodecylene, tetramethylene, pentamethylene or hexamethylene, a 1,2-vinylidene group of the formula —CH═CH—, a 1,2-, 1,3- or 1,4-phenylene group, or a heteroarylene group, for example based on the pyridine skeleton.
Compounds of the formula I which comprise benzene or pyridine skeletons for R¹are based, for example, on benzenedi-, -tri- or -tetracarboxylic acids such as phthalic acid (benzene-1,2-dicarboxylic acid), isophthalic acid (benzene-1,3-dicarboxylic acid), terephthalic acid (benzene-1,4-dicarboxylic acid), trimellitic acid (benzene-1,2,4-tri-carboxylic acid), trimesic acid (benzene-1,3,5-tricarboxylic acid) or pyromellitic acid (benzene-1,2,4,5-tetracarboxylic acid) or on pyridinedicarboxylic acids such as quinolinic acid (pyridine-2,3-dicarboxylic acid), lutidinic acid (pyridine-2,4-dicarboxylic acid), dipicolinic acid (pyridine-2,6-dicarboxylic acid) or dinicotinic acid (pyridine-3,5-dicarboxylic acid). In the case of pyromellitic acid having 4 carboxyl groups, a doubling of the dicarboxylic acid structure I can occur, such that the active structure of the solubilizer of the general formula I occurs twice in the molecule.
Hydrocarbylene radicals interrupted by heteroatoms from the group of O, S and N for R¹are especially C₁- to C₁₂-alkylene groups which comprise, incorporated in their chain, one, two or three oxygen, sulfur and/or nitrogen atoms, where, in the case of nitrogen atoms, their free valence is preferably saturated by a lower alkyl group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or tert-butyl; examples thereof are —CH₂—O—CH₂—, —CH₂CH₂—O—CH₂—CH₂—, —CH₂—N(CH₃)—CH₂—, —CH₂CH₂—N(CH₃)—CH₂—CH₂and —CH₂CH₂—O—CH₂CH₂—O—CH₂CH₂—.
When amino groups are present in protonated form or carboxylic acid groups in deprotonated form in the compounds of the general form 1, the accompanying counterions are such that the compounds I still have sufficient oil solubility. In the case of protonated amino groups, it is possible, for example, for carboxylates of long-chain fatty acids or long-chain alkanesulfonates to occur as anions; for this purpose, preference is given to using those having at least one C₈- to C₂₀-alkyl or -alkenyl radical. In the case of deprotonated carboxylic acids, preferably hydrocarbyl-substituted ammonium cations selected from the group of [H₃NR⁸]⁺, [H₂NR⁸R⁹]⁺ and [HNR⁸R⁹R¹⁰]⁺ occur as cations; the variables R⁸, R⁹and R¹⁰therein each independently denote preferably linear or branched alkyl radicals such as methyl, ethyl, vinyl, n-propyl, isopropyl, 1-propenyl, 2-propenyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, 2-ethylhexyl, neooctyl, nonyl, neononyl, decyl, 2-propylheptyl, neodecyl, undecyl, neoundecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl (stearyl), oleyl, linolyl, linolenyl, nonadecyl, eicosyl, hencosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl, squalyl or the constitution isomers thereof.
When the R², R³, R⁴, R⁵, R⁶or R⁷radicals are a hydrocarbyl radical having from 1 to 30 carbon atoms, it shall be understood here to mean a virtually purely hydrocarbon radical of any structure, which, however, provided that this does not distort the dominant hydrocarbon character, may still have, to a small degree, heteroatoms, for example O or N, and/or functional groups with heteroatoms, for example OH groups. This hydrocarbyl radical may be of saturated, unsaturated or aromatic nature; it may have a linear, branched or cyclic structure.
In the context of the present invention, such a hydrocarbyl radical having from 1 to 30 carbon atoms for one of the R², R³, R⁴, R⁵, R⁶or R⁷radicals is preferably a linear or branched alkyl or alkenyl radical such as methyl, ethyl, vinyl, n-propyl, isopropyl, 1-propenyl, 2-propenyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, 2-ethylhexyl, neooctyl, nonyl, neononyl, decyl, 2-propylheptyl, neodecyl, undecyl, neoundecyl, dodecyl, tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl (stearyl), oleyl, linolyl, linolenyl, nonadecyl, eicosyl, hencosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl, nonacosyl, squalyl or their constitutional isomers. Such relatively long-chain alkyl radicals may also stem from naturally occurring sources, especially from glycerides or the parent fatty acids.
In the context of the present invention, such a hydrocarbyl radical having from 1 to 30 carbon atoms for one of the R², R³, R⁴, R⁵, R⁶or R⁷radicals may also be an aryl, alkaryl or arylalkyl radical, for example phenyl, naphthyl, benzyl, 2-phenylethyl, 3-phenylpropyl, 4-phenylbutyl, or o-, m- or p-xylyl.
At least one of the R², R³, R⁴, R⁵, R⁶or R⁷radicals in the solubilizers I must have at least 4, preferably at least 6, especially at least 8, more preferably at least 10, in particular at least 12 carbon atoms, in order that the compounds I have the necessary oil solubility. Such relatively long-chain radicals are typically present in the form of linear or slightly branched alkyl or alkenyl chains as described above. The remaining R², R³, R⁴, R⁵, R⁶or R⁷radicals are then typically short-chain, i.e. they have generally from 1 to 4 carbon atoms, or the corresponding valences in the compound I are saturated by hydrogen.
In a preferred embodiment, at least one solubilizer I in which at least one of the R², R³, R⁴, R⁵, R⁶or R⁷radicals has at least 4, preferably at least 6, especially at least 8, more preferably at least 10, in particular at least 12 carbon atoms, is used for the present invention to homogenize additive concentrates.
In a further preferred embodiment, at least one solubilizer I in which the variable X is OH is used for the present invention; they are then especially dicarboxylic monoesters, dicarboxylic monothioesters or dicarboxylic monoamides.
In a further preferred embodiment, at least one solubilizer I which derives from maleic acid or phthalic acid, i.e. the bridging member R¹is a 1,2-vinylidene group of the formula —CH═CH— or a 1,2-phenylene group, is used for the present invention.
More preferably, the solubilizer I used in accordance with the invention is a monoamide of maleic acid or of phthalic acid (Y═NR⁶), in which at least one of the R²and R⁶radicals has at least 10 and especially at least 12 carbon atoms. Such maleic and phthalic monoamides satisfy the formula HOOC—R¹—CO—NR²R⁶(R¹=1,2-vinylidene or 1,2-phenylene) in which one of the R²and R⁶radicals or both R²and R⁶radicals are a hydrocarbyl radical having from 10 to 30 and from 12 to 30 carbon atoms respectively. One example thereof is the monoamide of maleic acid or phthalic acid and tridecylamine (R²=tridecyl, R⁶=H), which is obtainable in a known manner by reacting maleic acid or maleic anhydride, or phthalic acid or phthalic anhydride, with tridecylamine in an equimolar ratio. Preference is given here to using a tridecylamine which is present in the form of a mixture of structural isomers of n-tridecylamine and branched tridecylamines, where the proportion of n-tridecylamine is generally less than 70 mol%, especially less than 50 mol %, in particular less than 35 mol %.
The solubilizers I used in accordance with the invention are present in the additive concentrates generally in an amount of from 1.05 to 15% by weight, preferably from 1.25 to 13.5% by weight, more preferably from 1.5 to 12% by weight, especially from 2.0 to 10% by weight, in particular from 2.5 to 7% by weight, based in each case on the total amount of the additive concentrate. In most cases, the preferred ranges mention-ed are sufficient to obtain a sufficient homogenizing action in the additive concentrates. However, it is also possible to use more than 15% by weight of solubilizers 1, for example up to 20 or up to 30% by weight, but no further significant enhancement of the desired effect is thus achieved. In contrast to the upper limit, the lower limit for the amount of solubilizers I used in accordance with the invention is critical; it has been found that amounts up to 1% by weight are frequently still not sufficient to obtain the desired homogenization.
In the context of the present invention, cold flow improvers of component (A) shall be understood to mean all additives which improve the cold properties of fuel oil compositions. In addition to the actual cold flow improvers (“MDFIs”, for example ethylenevinyl acetate copolymers), these are in particular also nucleators, paraffin dispersants (“WASAs”, for example certain polar nitrogen compounds) or the combination of MDFIs and WASAs (“WAFIs”) (cf. also Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, Volume A16, p. 719 ff.).
Such cold flow improvers for the present invention as component

- (A) should advantageously be one or more representatives selected from
- (Aa) copolymers of ethylene with at least one further ethylenically unsaturated monomer;
- (Ab) comb polymers;
- (Ac) polyoxyalkylenes;
- (Ad) polar nitrogen compounds;
- (Ae) sulfocarboxylic acids or sulfonic acids or derivatives thereof; and/or (Af) poly(meth)acrylic esters.

In the copolymers of ethylene with at least one further ethylenically unsaturated monomer of group (Aa), the monomer is preferably selected from alkenylcarboxylic esters, (meth)acrylic esters and olefins.
Suitable olefins are, for example, those having from 3 to 10 carbon atoms and having from 1 to 3, preferably having 1 or 2 carbon-carbon double bonds, in particular having one carbon-carbon double bond. In the latter case, the carbon-carbon double bond may be arranged either terminally (α-olefins) or internally. However, preference is given to α-olefins, particular preference to α-olefins having from 3 to 8 carbon atoms, such as propene, 1-butene, 1-pentene, 1-hexene and 1-octene.
Suitable (meth)acrylic esters are, for example, esters of (meth)acrylic acid with C₁-C₁₄-alkanols, especially with methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, isobutanol, tert-butanol, pentanol, hexanol, heptanol, octanol, 2-ethylhexanol, nonanol, decanol, 2-propylheptanol, dodecanol and tetradecanol.
Suitable alkenylcarboxylic esters are, for example, the vinyl and propenyl esters of carboxylic acids having from 2 to 20 carbon atoms whose hydrocarbon radical may be linear or branched. Among these, preference is given to the vinyl esters. Among the carboxylic acids having a branched hydrocarbon radical, preference is given to those whose branch is disposed in the α-position to the carboxyl group, and particular preference is given to the α-carbon atom being tertiary, i.e. the carboxylic acid is a neocarboxylic acid. However, preference is given to the hydrocarbon radical of the carboxylic acid being linear.
Examples of suitable alkenylcarboxylic esters 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 alkenylcarboxylic ester is vinyl acetate; typical copolymers of group (Aa) resulting therefrom are ethylene-vinyl acetate copolymers (“EVA”), which are used in diesel fuels on a large scale.
Particular preference is given to the ethylenically unsaturated monomer being selected from alkenylcarboxylic esters.
Also suitable are copolymers which comprise two or more different copolymerized alkenylcarboxylic esters which differ in the alkenyl function and/or in the carboxylic acid group. Likewise suitable are copolymers which, in addition to the alkenylcarboxylic ester(s), comprise at least one copolymerized olefin and/or at least one copolymerized (meth)acrylic ester.
The ethylenically unsaturated monomer is copolymerized in the copolymer of group (Aa) in an amount of preferably from 1 to 50 mol %, more preferably from 10 to 50 mol % and in particular from 5 to 20 mol %, based on the overall copolymer.
The copolymer of group (Aa) preferably has a number-average molecular weight Mn of from 500 to 20 000, more preferably from 7500 to 10 000 and in particular from 1000 to 6000.
Comb polymers of group (Ab) are, for example, those described 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). Among those described there, suitable comb polymers are, for example, those of the formula II
where

D is R¹⁷, COOR¹⁷, OCOR¹⁷, R¹⁸, OCOR¹⁷or OR¹⁷,
E is H, CH₃, D or R¹⁸,
G is H or D,
J is H, R¹⁸, R¹⁸COOR¹⁷, aryl or heterocyclyl,
K is H, COOR¹⁸, OCOR¹⁸, OR¹⁸or COOH,
L is H, R¹⁸, COOR¹⁸, OCOR¹⁸, COOH or aryl,
where
R¹⁷is a hydrocarbon radical having at least 10 carbon atoms, preferably having from 10 to 30 carbon atoms,
R¹⁸is a hydrocarbon radical having at least one carbon atom, preferably having from 1 to 30 carbon atoms,
m is a molar fraction in the range from 1.0 to 0.4 and
n is a molar fraction in the range from 0 to 0.6.

Preferred comb polymers are, for example, obtainable by 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 preferred 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. Also suitable are mixtures of comb polymers. Comb polymers may also be polyfumarates or polymaleates. Homo- and copolymers of vinyl ethers are also suitable comb polymers.
Suitable polyoxyalkylenes of group (Ac) are, for example, polyoxyalkylene esters, ethers, ester/ethers and mixtures thereof. The polyoxyalkylene compounds preferably comprise at least one linear alkyl group, more preferably at least two linear alkyl groups, having from 10 to 30 carbon atoms and a polyoxyalkylene group having a molecular weight of up to 5000. The alkyl group of the polyoxyalkylene radical preferably comprises from 1 to 4 carbon atoms. Such polyoxyalkylene compounds are described, for example, in EP-A-0 061 895 and also in U.S. Pat. No. 4,491,455, which are hereby fully incorporated by reference. Preferred polyoxyalkylene esters, ethers and ester/ethers have the general formula Ill
R¹⁹[O—(CH₂)_y]_xO—R²⁰ (III)
in which

R¹⁹and R²⁰are each independently R²¹, R²¹—CO—, R²¹—O—CO(CH₂)₂— or R²¹—O—CO(CH₂)₂—
CO— where R²¹is linear C₁-C₃₀-alkyl,
y is from 1 to 4,
x is from 2 to 200, and
z is from 1 to 4.

Preferred polyoxyalkylene compounds of the formula III in which both R¹⁹and R²⁰are R²¹are polyethylene glycols and polypropylene glycols having a number-average molecular weight of from 100 to 5000. Preferred polyoxyalkylenes of the formula III in which one of the R¹⁹radicals is R²¹and the other is R²¹—CO— are polyoxyalkylene esters of fatty acids having from 10 to 30 carbon atoms, such as stearic acid or behenic acid. Preferred polyoxyalkylene compounds in which both R¹⁹and R²⁰are an R²¹—CO— radical are diesters of fatty acids having from 10 to 30 carbon atoms, preferably of stearic acid or behenic acid.
The polar nitrogen compounds of group (Ad), which are advantageously oil-soluble, may be either ionic or nonionic and preferably have at least one substituent, more preferably at least 2 substituents, of the formula >NR²²in which R²²is a C₈-C₄₀-hydrocarbon radical. The nitrogen substituents may also be quaternized, i.e. be in cationic form. An example of such nitrogen compounds is that of ammonium salts and/or amides which are obtainable by the reaction of at least one amine substituted by at least one hydrocarbon radical with a carboxylic acid having from 1 to 4 carboxyl groups or with a suitable derivative thereof. The amines preferably comprise at least one linear C₈-C₄₀-alkyl radical. Suitable primary amines are, for example, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tetradecylamine and the higher linear homologs. Suitable secondary amines are, for example, dioctadecylamine and methylbehenylamine. Also suitable are amine mixtures, in particular 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, cyclo-hexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, cyclopentane-1,2-di-carboxylic acid, naphthalenedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid and succinic acids substituted with long-chain hydrocarbon radicals.
A further example of polar nitrogen compounds of group (Ad) is that of ring systems which bear at least two substituents of the formula -A-NR²³R²⁴in which A is a linear or branched aliphatic hydrocarbon group which is optionally interrupted by one or more groups selected from O, S, NR³⁵and CO, and R²³and R²⁴are each a C₉-C₄₀-hydrocarbon radical which is optionally interrupted by one or more groups selected from O, S, NR³⁵and CO, and/or substituted by one or more substituents selected from OH, SH and NR³⁵R³⁶where R³⁵is C₁-C₄₀-alkyl which is optionally interrupted by one or more moieties selected from CO, NR³⁵, O and S, and/or substituted by one or more radicals selected from NR³⁷R³⁸, OR³⁷, SR³⁷, COR³⁷, COOR³⁷, CONR³⁷R³⁸, aryl or heterocyclyl, where R³⁷and R³⁸are each independently selected from H or C₁-C₄-alkyl; and R³⁶is H or R³⁵.
A is preferably a methylene or polymethylene group having from 2 to 20 methylene units. Examples of suitable R²³and R²⁴radicals are 2-hydroxyethyl, 3-hydroxypropyl, 4-hydroxybutyl, 2-ketopropyl, ethoxyethyl and propoxypropyl. The cyclic system may be homocyclic, heterocyclic, fused polycyclic or nonfused polycyclic systems. The ring system is preferably carbo- or heteroaromatic, in particular carboaromatic. Examples of such polycyclic ring systems are fused benzoid structures such as naphthalene, anthraxcene, phenanthrene and pyrene, fused nonbenzoid structures such as azulene, indene, hydrindene and fluorene, nonfused polycycles such as diphenyl, heterocycles such as quinoline, indole, dihydroindole, benzofuran, coumarin, isocoumarin, benzothiophene, carbazole, diphenylene oxide and diphenylene sulfide, nonaromatic or partially saturated ring systems such as decalin, and three-dimensional structures such as α-pinene, camphene, bornylene, norbornane, norbornene, bicyclooctane and bicyclooctene.
A further example of suitable polar nitrogen compounds is that of condensates of long-chain primary or secondary amines with carboxyl group-containing polymers.
The polar nitrogen compounds mentioned here are described in WO 00/44857 and also in the references cited therein, which are hereby fully incorporated by reference.
Suitable polar nitrogen compounds are also described, for example, in DE-A-198 48 621, DE-A-196 22 052 or EP-B 398 101, which are hereby incorporated by reference.
Suitable sulfo carboxylic acids/sulfonic acids or their derivatives of group (Ae) are, for example, those of the general formula IV
in which

Y′ is SO₃ ⁻(NR²⁵ ₃R²⁶)⁺, SO₃ ⁻(NHR²⁵ ₂R²⁶)⁺, SO₃ ⁻(NH₂R²⁵R²⁶), SO₃ ⁻(NH₃R²⁶) or
SO₂NR²⁵R²⁶,
X′ is Y′, CONR²⁵R²⁷, CO₂ ⁻(NR²⁵ ₃R²⁷)⁺, CO₂ ⁻(NHR²⁵ ₂R²⁷)⁺, R²⁸—COOR²⁷, NR²⁵COR²⁷, R²⁸OR²⁷, R²⁸OCOR²⁷, R²⁸R²⁷, N(COR²⁵)R²⁷or Z-(NR²⁵ ₃R²⁷)⁺,
where
R²⁵is a hydrocarbon radical,
R²⁶and R²⁷are each alkyl, alkoxyalkyl or polyalkoxyalkyl having at least 10 carbon atoms in the main chain,
R²⁸is C₂-C₅-alkylene,
Z— is one anion equivalent and
A′ and B are each alkyl, alkenyl or two substituted hydrocarbon radicals or, together with the carbon atoms to which they are bonded, form an aromatic or cycloaliphatic ring system.

Such sulfo carboxylic acids and sulfonic acids and their derivatives are described in EP-A-0 261 957, which is hereby fully incorporated by reference.
Suitable poly(meth)acrylic esters of group (Af) 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 in the esterified alcohol. Optionally, the copolymer comprises another different copolymerized olefinically unsaturated monomer. The weight-average molecular weight of the polymer is preferably from 50 000 to 500 000. A particularly preferred polymer is a copolymer of methacrylic acid and methacrylic esters of saturated C₁₄- and C₁₅-alcohols, in which the acid groups have been neutralized with hydrogenated tallamine. Suitable poly(meth)acrylic esters are described, for example, in WO 00/44857, which is hereby fully incorporated by reference.
The additive concentrates mentioned preferably comprise, as component (A), at least one cold flow improver of group (Aa) or a mixture of one or more cold flow improvers of group (Aa) and one or more cold flow improvers selected from the remaining groups (Ab) to (Af), especially a mixture of one or more cold flow improvers of group (Aa) and one or more cold flow improvers of group (Ad).
More preferably, the additive concentrates mentioned comprise, as cold flow improvers of components (A), one or more representatives selected from

- ethylene-vinyl acetate copolymers [representatives of group (Aa)];
- ethylene-vinyl propionate copolymers [representatives of group (Aa)];
- N,N-dialkylammonium salts of 2-N′,N′-dialkylamidobenzoates [representatives of group (Ad)], for example the reaction product formed from 1 mol of phthalic anhydride and 2 mol of ditallow fatty amine, the latter being hydrogenated or unhydrogenated;
- the reaction products of 1 mol of ethylenediaminetetraacetic acid with 4 mol of a dialkylamine [representatives of group (Ad)], for example the reaction product formed from 1 mol of ethylenediaminetetraacetic acid and 4 mol of ditallow fatty amine, the latter being hydrogenated or unhydrogenated;
- the reaction products of 1 mol of nitrilotriacetic acid with 3 mol of a dialkylamine [representatives of group (Ad)], for example the reaction product formed from 1 mol of nitrilotriacetic acid and 3 mol of ditallow fatty amine, the latter being hydrogenated or unhydrogenated;
- the reaction products of 1 mol of phthalic anhydride with 2 mol of a dialkylamine [representatives of group (Ad)], for example the reaction product formed from 1 mol of phthalic anhydride and 2 mol of ditallow fatty amine, the latter being hydrogenated or unhydrogenated;
- the reaction products of 1 mol of an alkenyl-spiro-bislactone with 2 mol of a dialkylamine [representatives of group (Ad)], for example the reaction product formed from 1 mol of an alkenyl-spiro-bislactone with 2 mol of ditallow fatty amine and/or tallow fatty amine, the latter two being hydrogenated or unhydrogenated;
- C₁₂- to C₁₈-alkyl fumarate-vinyl acetate or C₁₂- to C₁₈-alkyl fumarate-styrene comb polymers [representatives of group (Ab)], for example those in the molar ratio of the two monomer types of 1:1; and/or
- C₁₄- to C₂₀-alkyl itaconate comb polymers [representatives of group (Ab)].

The detergent additives of component (B) to be used in the additive concentrates mentioned are generally advantageously amphiphilic substances which have at least one hydrophobic hydrocarbon radical having a number-average molecular weight (Mn) of from 85 to 20 000 and at least one polar moiety which is selected from

- (Ba) mono- or polyamino groups having up to 6 nitrogen atoms, at least one nitrogen atom having basic properties;
- (Bb) nitro groups, if appropriate in combination with hydroxyl groups;
- (Bc) hydroxyl groups in combination with mono- or polyamino groups, at least one nitrogen atom having basic properties;
- (Bd) carboxyl groups or their alkali metal or alkaline earth metal salts;
- (Be) sulfonic acid groups or their alkali metal or alkaline earth metal salts;
- (Bf) polyoxy-C₂-C₄-alkylene moieties which are terminated by hydroxyl groups, mono- or polyamino groups, at least one nitrogen atom having basic properties, or by carbamate groups;
- (Bg) carboxylic ester groups;
- (Bh) moieties which derive from succinic anhydride and have hydroxyl and/or amino and/or amido and/or imido groups; and/or
- (Bi) moieties obtained by Mannich reaction of substituted phenols with aldehydes and mono- or polyamines.

The hydrophobic hydrocarbon radical in the above detergent additives, which ensures the adequate solubility in the fuel oil composition, has a number-average molecular weight (Mn) of from 85 to 20 000, especially from 113 to 10 000, in particular from 300 to 5000. Typical hydrophobic hydrocarbon radicals, especially in conjunction with the polar moieties (Ba), (Bc), (Bh) and (Bi), include relatively long-chain alkyl or alkenyl groups, especially the polypropenyl, polybutenyl and polyisobutenyl radical, each having Mn=from 300 to 5000, especially from 500 to 2500, in particular from 700 to 2300.
Examples of the above groups of detergent additives include the following:
Additives comprising mono- or polyamino groups (Ba) are preferably polyalkenemono- or polyalkenepolyamines based on polypropene or conventional (i.e. having predominantly internal double bonds) polybutene or polyisobutene having Mn=from 300 to 5000. When polybutene or polyisobutene having predominantly internal double bonds (usually in the beta- and gamma-position) are used as starting materials in the preparation of the additives, a possible preparative route is by chlorination and subsequent amination or by oxidation of the double bond with air or ozone to give the carbonyl or carboxyl compound and subsequent amination under reductive (hydrogenating) conditions. The amines used here for the amination may be, for example, ammonia, monoamines or polyamines, such as dimethylaminopropylamine, ethylenediamine, diethylenetriamine, triethylenetetramine or tetraethylenepentamine. Corresponding additives based on polypropene are described in particular in WO-A-94/24231.
Further preferred additives comprising monoamino groups (Ba) are the hydrogenation products of the reaction products of polyisobutenes having an average degree of polymerization P of from 5 to 100 with nitrogen oxides or mixtures of nitrogen oxides and oxygen, as described in particular in WO-A-97/03946.
Further preferred additives comprising monoamino groups (Ba) are the compounds obtainable from polyisobutene epoxides by reaction with amines and subsequent dehydration and reduction of the amino alcohols, as described in particular in DE-A-196 20 262.
Additives comprising nitro groups (Bb), if appropriate in combination with hydroxyl groups, are preferably reaction products of polyisobutenes having an average degree of polymerization P=from 5 to 100 or from 10 to 100 with nitrogen oxides or mixtures of nitrogen oxides and oxygen, as described in particular in WO-A-96/03367 and WO-A-96/03479. These reaction products are generally mixtures of pure nitropoly-isobutenes (e.g. α,β-dinitropolyisobutene) and mixed hydroxynitropolyiso-butenes (e.g. α-nitro-β-hydroxypolyisobutene).
Additives comprising hydroxyl groups in combination with mono- or polyamino groups (Bc) are in particular reaction products of polyisobutene epoxides obtainable from polyisobutene having preferably predominantly terminal double bonds and Mn=from 300 to 5000, with ammonia or mono- or polyamines, as described in particular in EP-A 476 485.
Additives comprising carboxyl groups or their alkali metal or alkaline earth metal salts (Bd) are preferably copolymers of C₂-C₄₀-olefins with maleic anhydride which have a total molar mass of from 500 to 20 000 and of whose carboxyl groups some or all have been converted to the alkali metal or alkaline earth metal salts and any remainder of the carboxyl groups has been reacted with alcohols or amines. Such additives are disclosed in particular by EP-A-307 815. Such additives serve mainly to prevent valve seat wear and can, as described in WO-A-87/01126, advantageously be used in combination with customary fuel detergents such as poly(iso)buteneamines or polyetheramines.
Additives comprising sulfonic acid groups or their alkali metal or alkaline earth metal salts (Be) are preferably alkali metal or alkaline earth metal salts of an alkyl sulfosuccinate, as described in particular in EP-A-639 632. Such additives serve mainly to prevent valve seat wear and can be used advantageously in combination with customary fuel detergents such as poly(iso)buteneamines or polyetheramines.
Additives comprising polyoxy-C₂-C₄-alkylene moieties (Bf) are preferably polyethers or polyether amines which are obtainable by reaction of C₂-C₆₀-alkanols, C₆-C₃₀-alkane-diols, mono- or di-C₂-C₃₀-alkylamines, C₁-C₃₀-alkylcyclohexanols or C₁-C₃₀-alkylphenols with from 1 to 30 mol of ethylene oxide and/or propylene oxide and/or butylene oxide per hydroxyl group or amino group and, in the case of the polyether amines, by subsequent reductive amination with ammonia, monoamines or polyamines. Such products are described in particular in EP-A-310 875, EP-A-356 725, EP-A-700 985 and U.S. Pat. No. 4,877,416. In the case of polyethers, such products also have carrier oil properties. Typical examples of these are tridecanol butoxylates, isotridecanol butoxylates, isononylphenol butoxylates and polyisobutenol butoxylates and propoxylates and also the corresponding reaction products with ammonia.
Additives comprising carboxylic ester groups (Bg) are preferably esters of mono-, di- or tricarboxylic acids with long-chain alkanols or polyols, in particular those having a minimum viscosity of 2 mm²/s at 100° C., as described in particular in DE-A-38 38 918. The mono-, di- or tricarboxylic acids used may be aliphatic or aromatic acids, and particularly suitable ester alcohols or ester polyols are long-chain representatives having, for example, from 6 to 24 carbon atoms. Typical representatives of the esters are adipates, phthalates, isophthalates, terephthalates and trimellitates of isooctanol, of isononanol, of isodecanol and of isotridecanol. Such products also have carrier oil properties.
Additives comprising moieties derived from succinic anhydride and having hydroxyl and/or amino and/or amido and/or imido groups (Bh) are preferably corresponding derivatives of alkyl- or alkenyl-substituted succinic anhydride and especially the corresponding derivatives of polyisobutenylsuccinic anhydride which are obtainable by reacting conventional or highly reactive polyisobutene having Mn=from 300 to 5000 with maleic anhydride by a thermal route or via the chlorinated polyisobutene. Particular interest attaches to derivatives with aliphatic polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine or tetraethylenepentamine. The moieties having hydroxyl and/or amino and/or amido and/or imido groups are, for example, carboxylic acid groups, acid amides of monoamines, acid amides of di- or polyamines which, in addition to the amide function, also have free amine groups, succinic acid derivatives having an acid and an amide function, carboximides with monoamines, carboximides with di- or polyamines which, in addition to the imide function, also have free amine groups, or diimides which are formed by the reaction of di- or polyamines with two succinic acid derivatives. Such fuel additives are described in particular in U.S. Pat. No. 4,849,572.
Additives comprising moieties (Bi) obtained by Mannich reaction of substituted phenols with aldehydes and mono- or polyamines are preferably reaction products of polyisobutene-substituted phenols with formaldehyde and mono- or polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine or dimethylaminopropylamine. The polyisobutenyl-substituted phenols may stem from conventional or highly reactive polyisobutene having Mn=from 300 to 5000. Such “polyisobutene-Mannich bases” are described in particular in EP-A-831 141.
For a more precise definition of the fuel additives detailed individually, reference is explicitly made here to the disclosures of the abovementioned prior art documents. Particular preference is given to detergent additives from group (Bh). These are preferably the reaction products of alkyl- or alkenyl-substituted succinic anhydrides, especially of polyisobutenylsuccinic anhydrides, with amines. It will be appreciated that these reaction products are not obtainable only when substituted succinic anhydride is used, but also when substituted succinic acid or suitable acid derivatives, such as succinyl halides or succinic esters, are used.
In a particularly preferred embodiment, the additive concentrates mentioned comprise, as a detergent additive of component (B), one or more derivatives which have been derived from polyisobutenylsuccinic anhydride and have amino and/or amido and/or imido groups. Particularly preferred detergent additives in this context are polyisobutenyl-substituted succinimides, especially the imides with aliphatic polyamines. Particularly preferred polyamines are diethylenetriamine, tetraethylenepentamine and pentaethylenehexamine, particular preference being given to tetraethylenepentamine. The polyisobutenyl radical has a number-average molecular weight Mn of preferably from 500 to 5000, more preferably from 500 to 2000 and in particular of about 1000.
In a further preferred embodiment, the detergent additives mentioned are used in combination with at least one carrier oil in the additive concentrates mentioned. Suitable mineral carrier oils are the fractions obtained in crude oil processing, such as brightstock or base oils having viscosities, for example, from the SN 500-2000 class; but also aromatic hydrocarbons, paraffinic hydrocarbons and alkoxyalkanols. Likewise useful is a fraction which is obtained in the refining of mineral oil and is known as “hydrocrack oil” (vacuum distillate cut having a boiling range of from about 360 to 500° C., obtainable from natural mineral oil which has been catalytically hydrogenated under high pressure and isomerized and also deparaffinized). Likewise suitable are mixtures of abovementioned mineral carrier oils.
Examples of suitable synthetic carrier oils are selected from: polyolefins (poly-alpha-olefins or poly(internal olefin)s), (poly)esters, (poly)alkoxylates, polyethers, aliphatic polyether amines, alkylphenol-started polyethers, alkylphenol-started polyether amines and carboxylic esters of long-chain alkanols.
Examples of suitable polyolefins are olefin polymers having Mn=from 400 to 1800, in particular based on polybutene or polyisobutene (hydrogenated or unhydrogenated).
Examples of suitable polyethers or polyetheramines are preferably compounds comprising polyoxy-C₂-C₄-alkylene moieties which are obtainable by reacting C₂-C₆₀-alkanols, C₆-C₃₀-alkanediols, mono- or di-C₂-C₃₀-alkylamines, C₁-C₃₀-alkylcyclohexanols or C₁-C₃₀-alkylphenols with from 1 to 30 mol of ethylene oxide and/or propylene oxide and/or butylene oxide per hydroxyl group or amino group, and, in the case of the polyether amines, by subsequent reductive amination with ammonia, monoamines or polyamines. Such products are described in particular in EP-A-310 875, EP-A-356 725, EP-A-700 985 and U.S. Pat. No. 4,877,416. For example, the polyether amines used may be poly-C₂-C₆-alkylene oxide amines or functional derivatives thereof. Typical examples thereof are tridecanol butoxylates or isotridecanol butoxylates, isononylphenol butoxylates and also polyisobutenol butoxylates and propoxylates, and also the corresponding reaction products with ammonia.
Examples of carboxylic esters of long-chain alkanols are in particular esters of mono-, di- or tricarboxylic acids with long-chain alkanols or polyols, as described in particular in DE-A-38 38 918. The mono-, di- or tricarboxylic acids used may be aliphatic or aromatic acids; suitable ester alcohols or polyols are in particular long-chain representatives having, for example, from 6 to 24 carbon atoms. Typical representatives of the esters are adipates, phthalates, isophthalates, terephthalates and trimellitates of isooctanol, isononanol, isodecanol and isotridecanol, for example di-(n- or isotridecyl) phthalate.
Further suitable carrier oil systems are described, for example, in DE-A-38 26 608, DE-A-41 42 241, DE-A-43 09 074, EP-A-0 452 328 and EP-A-0 548 617, which are explicitly incorporated herein by way of reference.
Examples of particularly suitable synthetic carrier oils are alcohol-started polyethers having from about 5 to 35, for example from about 5 to 30, C₃-C₆-alkylene oxide units, for example selected from propylene oxide, n-butylene oxide and isobutylene oxide units, or mixtures thereof. Nonlimiting examples of suitable starter alcohols are long-chain alkanols or phenols substituted by long-chain alkyl in which the long-chain alkyl radical is in particular a straight-chain or branched C₆-C₁₈-alkyl radical. Preferred examples include tridecanol and nonylphenol.
Further suitable synthetic carrier oils are alkoxylated alkylphenols, as described in DE-A-10 102 913.6.
Preferred carrier oils are synthetic carrier oils, particular preference being given to polyethers.
When a carrier oil is also incorporated into the additive concentrate, it is added typically in an amount of from 10% by weight to 100% by weight, preferably from 20 to 70% by weight, based in each case on the amount of detergent additive of component (B).
The inert organic solvents or solvent mixtures of component (C) used in the additive concentrates mentioned are generally those which are selected from hydrocarbons, alcohols, carboxylic esters or mixtures thereof. “Inert” means here that such organic solvents exert no significant interactions, if any, with the active components in the additive concentrates or enter into chemical reactions with them under use conditions. Such inert organic solvents or solvent mixtures are essentially free of further organic compounds with functional groups. Typical hydrocarbon solvents suitable as component (C) are n-pentane, n-hexane, n-heptane, cyclohexane, methylcyclohexane, toluene, xylenes, technical hydrocarbon mixtures such as Solvent Naphtha, as are commercially obtainable, for example, under the name Solvesso® 150, and fuels themselves. Typical alcohols suitable as component (C) are methanol, ethanol, n-propanol, isopropanol, n-butanol, tert-butanol, 2-ethylhexanol and 2-propylheptanol. Carboxylic esters suitable as component (C) are, for example, fatty acid lower alkyl esters, especially fatty acid methyl esters.
The cetane number improvers of component (D) are also referred to as ignition or combustion improvers. The component (D) to be used in the additive concentrates mentioned is preferably at least one cetane number improver which is selected from organic nitrates. Such organic nitrates are especially nitrate esters of unsubstituted or substituted, aliphatic or cycloaliphatic alcohols, usually having up to about 10 and in particular having from 2 to 10 carbon atoms. The alkyl group in these nitrate esters may be linear or branched, saturated or unsaturated. Typical examples of such nitrate esters are methyl nitrate, ethyl nitrate, n-propyl nitrate, isopropyl nitrate, allyl nitrate, n-butyl nitrate, isobutyl nitrate, sec-butyl nitrate, tert-butyl nitrate, n-amyl nitrate, isoamyl nitrate, 2-amyl nitrate, 3-amyl nitrate, tert-amyl nitrate, n-hexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate, n-octyl nitrate, 2-ethylhexyl nitrate, sec-octyl nitrate, n-nonyl nitrate, n-decyl nitrate, 2-propylheptyl nitrate, cyclopentyl nitrate, cyclohexyl nitrate, methylcyclohexyl nitrate and isopropylcyclohexyl nitrate. Additionally suitable are, for example, nitrate esters of alkoxy-substituted aliphatic alcohols, such as 2-ethoxyethyl nitrate, 2-(2-ethoxyethoxy)ethyl nitrate, 1-methoxypropyl nitrate or 4-ethoxybutyl nitrate. Also suitable are diol nitrates such as 1,6-hexamethylene dinitrate. Among the cetane number improver classes mentioned, primary amyl nitrates, primary hexyl nitrates, octyl nitrates and mixtures thereof are preferred.
Particular preference is given to 2-ethylhexyl nitrate as component (D). 2-Ethylhexyl nitrate may be present as the sole cetane number improver or in a mixture with other cetane number improvers.
In addition, the additive concentrates mentioned may comprise further customary coadditives, especially boosters for the cold flow improvers (A), such as oleic acid-diethylenetriamine reaction products, corrosion inhibitors, deicing agents such as ethylene glycol mono- or dimethyl ethers, demulsifiers, dehazers, antifoams, lubricity improvers, metal deactivators, antioxidants or stabilizers, antistats, metallocenes, markers and/or dyes. These customary coadditives are, if desired, added in amount relative to the components (A) to (C) or (A) to (D) which are customary therefor.
In the context of the present invention, fuel oil compositions shall be understood to mean middle distillate fuels which boil within the range of 120-500° C., renewable fuels and mixtures thereof. Such middle distillate fuels are in particular diesel fuel, heating oil or kerosene, particular preference being given to heating oil and in particular diesel fuel. Such renewable fuels are bioethanol and in particular biodiesel.
The heating oils are, for example, low-sulfur or sulfur-rich crude oil raffinates or bituminous or brown coal distillates which typically have a boiling range of from 150 to 400° C. The heating oils may be standard heating oil according to DIN 51603-1, which has a sulfur content of from 0.005 to 0.2% by weight, or they are low-sulfur heating oils having a sulfur content of from 0 to 0.005% by weight. Examples of heating oil include in particular heating oil for domestic oil-fired boilers or EL heating oil. The quality requirements for such heating oils are laid down, for example, in DIN 51603-1 (cf. also Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, Volume A12, p. 617 ff., which is hereby explicitly incorporated by reference).
The diesel fuels are, for example, crude oil raffinates which typically have a boiling range from 100 to 400° C. These are usually distillates having a 95% point up to 360° C. or even higher. They may also be so-called “ultra low sulfur diesel” or “city diesel”, characterized by a 95% point of, for example, not more than 345° C. and a sulfur content of not more than 0.005% by weight, or by a 95% point of, for example, 285° C. and a sulfur content of not more than 0.001% by weight. In addition to the diesel fuels obtainable by refining crude oil, suitable diesel fuels also include those obtainable by coal gasification or gas liquefaction [“gas-to-liquid” (“GTL”) fuels] or by biomass liquefaction [“biomass-to-liquid” (“BTL”) fuels]. Also suitable are mixtures of the aforementioned diesel fuels with renewable fuels such as biodiesel or bioethanol.
The diesel fuels are more preferably those having a low sulfur content, i.e. having a sulfur content of less than 0.05% by weight, preferably of less than 0.02% by weight, in particular of less than 0.005% by weight and especially of less than 0.001% by weight of sulfur.
Biodiesel (also referred to as biofuel oil) preferably comprises essentially alkyl esters of fatty acids which derive from vegetable and/or animal oils and/or fats. Alkyl esters are understood to mean typically lower alkyl esters, especially C₁- to C₄-alkyl esters, which are obtainable by transesterifiying the glycerides which occur in vegetable and/or animal oils and/or fats, especially triglycerides, by means of lower alcohols, for example ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol or especially methanol (“FAME”: fatty acid methyl esters).
The examples of vegetable oils which are converted to corresponding alkyl esters and can thus serve as the basis for biodiesel are castor oil, olive oil, peanut oil, palm kernel oil, coconut oil, mustard oil, cottonseed oil and especially sunflower oil, palm oil, soybean oil and rapeseed oil. Further examples include oils which can be obtained from wheat, jute, sesame and the shea tree nut; it is also possible to use arachis oil, jatropha oil and linseed oil.
It is also possible to convert vegetable oils which have already been used, for example used deep fat fryer oil, if appropriate after appropriate cleaning, to alkyl esters and hence for them to serve as the basis for biodiesel.
Vegetable fats are likewise usable in principle as a source for biodiesel, but are of minor importance.
Examples of animal fats and oils which are converted to corresponding alkyl esters and can thus serve as the basis for biodiesel are fish oil, bovine tallow, porcine tallow and similar fats and oils obtained as wastes in the slaughter or utilization of farm animals or wild animals.
The parent saturated or unsaturated fatty acids of the vegetable and/or animal oils and/or fats mentioned, said fatty acids usually having from 12 to 22 carbon atoms and possibly bearing additional functional groups such as hydroxyl groups, which occur in the alkyl esters are especially lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, elaidic acid, erucic acid and ricinoleic acid, especially in the form of mixtures of such fatty acids.
Typical lower alkyl esters based on vegetable and/or animal oils and/or fats which find use as biodiesel or biodiesel components are, for example, sunflower methyl ester, palm oil methyl ester (“PME”), soybean oil methyl ester (“SME”) and especially rapeseed oil methyl ester (“RME”).
However, it is also possible to use the monoglycerides, diglycerides and especially triglycerides themselves, for example castor oil, or mixtures of such glycerides as biodiesel or components for biodiesel.
The present invention also provides additive concentrates suitable for additizing fuel oil compositions which consist predominantly of a middle distillate fuel which boils in the range of 120-500° C. and/or a renewable fuel, said additive concentrate comprising at least one solubilizer of the general formula I
in which

- R¹denotes a hydrocarbylene radical having from 1 to 12 carbon atoms or a hydrocarbylene radical which has from 2 to 12 carbon atoms, is interrupted by one or more heteroatoms selected from the group of O, S and N, and may in each case bear one or more functional groups selected from the group of OH, OR³, NH₂, NHR⁴, NR⁴R⁵, COOH, COOR⁷, CONHR⁴and CONR⁴R⁵, where amino groups may also be present in protonated form and carboxylic acid groups also in deprotonated form,

X is OH, OR³, NH₂, NHR⁴or NR⁴R⁵, where, in the case that X together with the adjacent carbonyl group is a carboxylic acid radical, this radical is present in deprotonated form and the accompanying cation may be a hydrocarbyl-substituted ammonium cation selected from the group of [H₃NR⁸]⁺, [H₂NR⁸R⁹]⁺ and [HNR⁸R⁹R¹⁰]⁺,

- Y is O, S, NH or NR⁶, or, in the case that X is NH₂or NHR⁴, is a chemical bond to X with formation of an imide structure,

where R²to R¹⁰are each independently hydrocarbyl radicals having from 1 to 30 carbon atoms,
with the proviso that at least one of the R², R³, R⁴, R⁵, R⁶and R⁷radicals has at least 4 carbon atoms,
in an amount of from 1.05 to 15% by weight, based on the total amount of the additive concentrate, and

The additive concentrates mentioned preferably additionally comprise

(D) at least one cetane number improver.

In a preferred embodiment, the inventive additive concentrates comprise

The additive concentrates mentioned may additionally comprise further ingredients, in which case the sum of all ingredients adds up to 100% by weight.
The solubilizers of the general formula I used in accordance with the invention ensure sufficient homogenization of additive concentrates which comprise both cold flow improvers and detergent additives, and also inert organic solvents and if appropriate cetane number improvers, by stabilizing them such that no flaky precipitates or opacity occur in the course of formulation or storage - even in the course of storage over prolonged periods, for example over several weeks - of the additive concentrates. The examples which follow are intended to illustrate this effect of the solubilizers 1.

APPLICATION EXAMPLES

Additive concentrates composed of the following components were prepared by mixing:


Solubilizer L1:	Monoamide formed from maleic acid and
	tridecylamine (isomer mixture with <50 mol % of
	n-tridecylamine)
	[HOOC—CH═CH—CO—NH—C₁₃H₂₇]
Solubilizer L2:	Monoamide formed from succinic acid and
	tridecylamine (isomer mixture with <50 mol % of
	n-tridecylamine)
	[HOOC—CH₂—CH₂—CO—NH—C₁₃H₂₇]
Solubilizer L3:	Monoamide formed from n-decylsuccinic acid and
	tridecylamine (isomer mixture with <50 mol % of
	n-tridecylamine)
	[HOOC—CH(C₁₀H₂₁)—CH₂—CO—NH—C₁₃H₂₇]
Cold flow improver A1:	Commercial reaction product formed from 1 mol of
	ethylenediaminetetraacetic acid and 4 mol of
	hydrogenated ditallow fat amine [cold flow improver
	of group (Ad), especially effective as a paraffin
	dispersant (“WASA”)]
Cold flow improver A2:	Commercial ethylene-vinyl acetate-acrylate
	copolymer [cold flow improver of group (Aa)]
Detergent additive B1:	Commercial polyisobutylenesuccinamide based on
	an aliphatic polyamine [detergent component with the
	(Bh) moiety]
Solvent C1:	Solvent Naphtha (Solvesso ® 150)
Cetane number improver D1:	2-Ethylhexyl nitrate
Deicing agent E1:	Ethylene glycol monomethyl ether
Booster F1:	Customary oleic acid-diethylenetriamine reaction
	product

The degree of homogenization of the additive concentrates prepared was assessed visually by the following rating scale:

Rating 1=no precipitate, clear solution
Rating 2=no precipitate, slight turbidity, translucent
Rating 3=no precipitate, high opacity
Rating 4=flaky precipitates, dispersed
Rating 5=flaky precipitates, settled
Rating 6=severe precipitates, sedimented, or solution gelated

The compositions of the additive concentrate prepared and the assessment of their degree of homogenization according to the above rating scale is evident from the table below (the composition of the additive concentrates is reported in each case in % by weight). In all cases, L1 or at least the majority of L1 was added as the last component. The state of the additive concentrates thus prepared which was rated remained stable in each case for a prolonged period.

TABLE

Rating of the degree of homogenization of additive concentrates

Example	L1	L2	L3	A1	A2	B1	C1	D1	E1	F1	Rating

1 (for	1.0	0	0	4.3	0	3.0	60	30.9	0	0.8	6
compar-
ison)
2 (inventive)	3.0	0	0	4.3	0	3.0	60	28.9	0	0.8	1
3 (for	1.0	0	0	4.3	0	3.0	60	20.9	10	0.8	5**
compar-
ison)
4 (inventive)	6.0	0	0	4.3	0	3.0	60	15.9	10	0.8	1*
5 (for	1.0	0	0	4.3	7.2	3.0	60	13.7	10	0.8	4-5
compar-
ison)
6 (inventive)	4.0	0	0	4.3	7.2	3.0	60	10.7	10	0.8	3
7 (inventive)	1.0	3.0	0	4.3	0	3.0	60	17.9	10	0.8	1*
8 (inventive)	1.0	0	3.0	4.3	0	3.0	60	17.9	10	0.8	1*

*Rating immediately after mixing and constant after storage at 25° C. for 4 weeks
**Rating immediately after mixing: 2, after 1 h: 4, after 3 days: 4, after 4 weeks: 5

Claims

1. The use of at least one solubilizer of the general formula I

in which

R¹denotes a hydrocarbylene radical having from 1 to 12 carbon atoms or a hydrocarbylene radical which has from 2 to 12 carbon atoms, is interrupted by one or more heteroatoms selected from the group of O, S and N, and may in each case bear one or more functional groups selected from the group of OH, OR³, NH₂, NHR⁴, NR⁴R⁵, COOH, COOR⁷, CONHR⁴and CONR⁴R⁵, where amino groups may also be present in protonated form and carboxylic acid groups also in deprotonated form,

Y is O, S, NH or NR⁶, or, in the case that X is NH₂or NHR⁴, is a chemical bond to X with formation of an imide structure,

where R²to R¹⁰are each independently hydrocarbyl radicals having from 1 to 30 carbon atoms,

with the proviso that at least one of the R², R³, R⁴, R⁵, R⁶and R⁷radicals has at least 4 carbon atoms,

for homogenizing additive concentrates suitable for additizing fuel oil compositions which consist predominantly of a middle distillate fuel which boils in the range of 120-500° C. and/or a renewable fuel, said additive concentrates comprising

(A) at least one cold flow improver,

(B) at least one detergent additive and

(C) an inert organic solvent or a mixture of such solvents.

2. The use of at least one solubilizer I according to claim 1 for homogenizing additive concentrates which additionally comprise

(D) at least one cetane number improver.

3. The use of at least one solubilizer I according to claim 1 or 2 for homogenizing additive concentrates which comprise

(A) from 1 to 50% by weight of at least one cold flow improver,

(B) from 0.5 to 40% by weight of at least one detergent additive,

(C) from 0 to 80% by weight of at least one cetane number improver, and

(D) from 1 to 60% by weight of an inert organic solvent or of a mixture of such solvents.

4. The use of at least one solubilizer I according to claims 1 to 3 for homogenizing additive concentrates in an amount of from 1.05 to 15% by weight, based on the total amount of the additive concentrate.

5. The use of at least one solubilizer I according to claims 1 to 4 for homogenizing additive concentrates comprising, as a cold flow improver, one or more representatives selected from

(Aa) copolymers of ethylene with at least one further ethylenically unsaturated monomer;

(Ab) comb polymers;

(Ac) polyoxyalkylenes;

(Ad) polar nitrogen compounds;

(Ae) sulfocarboxylic acids or sulfonic acids or derivatives thereof; and/or (Af) poly(meth)acrylic esters.

6. The use of at least one solubilizer I according to claim 5 for homogenizing additive concentrates, comprising, as a cold flow improver, one or more representatives selected from

ethylene-vinyl acetate copolymers;

ethylene-vinyl propionate copolymers;

N,N-dialkylammonium salts of 2-N′,N′-dialkylamidobenzoates;

the reaction products of 1 mol of ethylenediaminetetraacetic acid with 4 mol of a dialkylamine;

the reaction products of 1 mol of nitrilotriacetic acid with 3 mol of a dialkylamine;

the reaction products of 1 mol of phthalic anhydride with 2 mol of a dialkylamine;

the reaction products of 1 mol of an alkenyl-spiro-bislactone with 2 mol of a dialkylamine;

C₁₂- to C₁₈-alkyl fumarate-vinyl acetate or C₁₂- to C₁₈-alkyl fumarate-styrene comb polymers; and/or

C₁₄- to C₂₀-alkyl itaconate comb polymers.

7. The use of at least one solubilizer I according to claims 1 to 6 for homogenizing additive concentrates, comprising, as detergent additive (B), one or more amphiphilic substances which have at least one hydrophobic hydrocarbon radical having a number-average molecular weight (Mn) of from 85 to 20 000 and at least one polar moiety which is selected from

(Ba) mono- or polyamino groups having up to 6 nitrogen atoms, at least one nitrogen atom having basic properties;

(Bb) nitro groups, if appropriate in combination with hydroxyl groups;

(Bc) hydroxyl groups in combination with mono- or polyamino groups, at least one nitrogen atom having basic properties;

(Bd) carboxyl groups or their alkali metal or alkaline earth metal salts;

(Be) sulfonic acid groups or their alkali metal or alkaline earth metal salts;

(Bf) polyoxy-C₂-C₄-alkylene moieties which are terminated by hydroxyl groups, mono- or polyamino groups, at least one nitrogen atom having basic properties, or by carbamate groups;

(Bg) carboxylic ester groups;

(Bh) moieties which derive from succinic anhydride and have hydroxyl and/or amino and/or amido and/or imido groups; and/or

(Bi) moieties obtained by Mannich reaction of substituted phenols with aldehydes and mono- or polyamines.

8. The use of at least one solubilizer I according to claim 7 for homogenizing additive concentrates, comprising, as detergent additive (B), one or more derivatives which derive from polyisobutenylsuccinic anhydride and have amino and/or amido and/or imido groups.

9. The use of at least one solubilizer I according to claims 1 to 8 for homogenizing additive concentrates in which the inert organic solvents (C) are selected from hydrocarbons, alcohols, carboxylic esters or mixtures thereof.

10. The use of at least one solubilizer I according to claims 2 to 9 for homogenizing additive concentrates in which the at least one cetane number improver (D) is selected from organic nitrates.

11. The use of at least one solubilizer I according to claims 1 to 10 for homogenizing additive concentrates where at least one of the R², R³, R⁴, R⁵, R⁶or R⁷radicals in said solubilizer has at least 10 carbon atoms.

12. The use of at least one solubilizer I according to claims 1 to 10 for homogenizing additive concentrates, where X in said solubilizer is OH.

13. The use of at least one solubilizer I according to claims 1 to 12 for homogenizing additive concentrates, said solubilizer deriving from maleic acid or phthalic acid.

14. The use of at least one solubilizer I according to claims 1 to 13 for homogenizing additive concentrates, said solubilizer being a monoamide of maleic acid or of phthalic acid, in which at least one of the R²or R⁶radicals has at least 10 carbon atoms.

15. An additive concentrate suitable for additizing fuel oil compositions which consist predominantly of a middle distillate fuel which boils in the range of 120-500° C. and/or a renewable fuel, said additive concentrate comprising at least one solubilizer of the general formula I

in which

in an amount of from 1.05 to 15% by weight, based on the total amount of the additive concentrate, and

(A) at least one cold flow improver,

(B) at least one detergent additive and

(C) an inert organic solvent or a mixture of such solvents.