KR20090081376A - Oligo- or polyamines as oxidation stabilizers for biofuel oils - Google Patents

Abstract

Use of oligo-or polyamines having a number-average molecular weight of 46 to 70 000 which are free from phenolic hydroxyl groups for increasing the oxidation stability of biofuel oils which are based on esters of fatty acids, or of mixtures of such biofuel oils with medium distillates of fossil origin and/or of plant and/or animal origin, which are essentially hydrocarbon mixtures and are free of esters of fatty acids.

Description

Oligoamines or polyamines as oxidation stabilizers for biofuel oils

The present invention relates to biofuel oils based on fatty acid esters, or to such distillates of fossil origin and / or vegetable and / or animal origin, which are predominantly hydrocarbon mixtures and contain no fatty acid esters. To increase the oxidative stability of the mixture, it relates to the use of oligoamines or polyamines having a number average molecular weight of 46 to 70,000 and containing no phenolic hydroxyl groups.

In addition, the present invention relates to mixtures of certain representative examples of such oligoamines or polyamines with biofuel oils based on fatty acid esters.

In addition, the present invention

(A) 0.1 to 75% by weight of one or more biofuel oils based on fatty acid esters, and

(B) 25 to 99.9% by weight of intermediate distillates of fossil origin and / or vegetable and / or animal origin, predominantly hydrocarbon mixtures and free of fatty acid esters

A large proportion of fuel oil, and

Specific representative examples of such oligoamines or polyamines in minor proportions

It relates to a fuel comprising a.

Biofuel oils, also commonly referred to as "biodiesel" and generally containing a high proportion of unsaturated fatty acid esters, are more sensitive to oxidative degradation by atmospheric oxygen than their fuel oils of fossil origin because of their chemical structure, and therefore their oxidation during storage. Stability is often improved by mixing it with small amounts of antioxidants. Antioxidants typically used for this purpose include literature articles from Mittelbach and Schover (JAOCS, Vol. 80, 8 (2003), p. 817-823, sterically hindered phenols such as 2,6-di-tert-butyl-4-methylphenol ("BHT"), 3-tert-butylhydroxyanisole ("BHA") And tert-butylhydroquinone ("TBHQ"). Certain sulfide esters, trivalent phosphorus compounds, metal dithiocarbamates and metal dithiophosphates are also used for this purpose.

In addition, BASF from November 1997 found that Kerobit ^® BPD, a secondary aromatic amine of the N, N-di-sec-butyl-p-phenylenediamine structure, is suitable as an antioxidant for gasoline and jet fuel. It is known from the technical information literature from BASF Aktiengesellschaft.

WO 03/095593 is an additive for improving the thermal stability of aviation fuels, and also biofuels, for example vegetable oils and esters of vegetable oils, comprising primary C ₄ -C ₂₉ -alkyl- or -alkenylsuccinic anhydrides. Succinimides are shown which can be obtained by reacting with amines (which may also be polyamines).

The documents WO 02/102942 and EP-A 1 568 756 disclose the suitability of polyisobutenylsuccinimides as detergents in biofuel oils.

WO 94/19430 describes the reaction products of polyamines with acylating agents, in particular fatty acids, as antifoams for mixtures of biofuel oils with intermediate distillates of fossil origin.

DE 10 2004 024 532 A1 contains a small proportion of fat-soluble oligoethyleneimines or polyethyleneimines that are alkoxylated with a plurality of ratios of intermediate distillate fuel oils and biofuel oils, and thus alkoxylated with ethylene oxide or propylene oxide. A fuel oil is disclosed. However, such alkoxylated oligoethyleneimines or polyethyleneimines serve as oil / water separators for mixtures of fuel and water in this document.

However, the stabilizing action of the antioxidants described above in biofuel oils is generally still insufficient, such as the stabilizing action of sterically hindered phenols. In particular, the required dose is too high. Accordingly, it is an object of the present invention to provide more effective antioxidants for biofuel oils.

The object is achieved by the use of oligoamines or polyamines having a number average molecular weight of 46 to 70,000 for increasing oxidative stability and containing no phenolic hydroxyl groups.

Cationic structures, in particular ammonium or substituted ammonium compounds, are preferably excluded from the oligoamines or polyamines to be used according to the invention.

The number average molecular weight of the oligoamines or polyamines is 46 to 70,000 (for the smallest possible representative for diaminomethane), but the upper limit thereof is not critical. Preferred ranges for the number average molecular weight are 58 to 40,000 (eg for 1,2-ethylenediamine), especially 116 to 10,000, especially 130 to 5,000, most preferably 200 to 2,000.

The oligoamines or polyamines mentioned preferably have from 2 to 10, in particular from 2 to 6, in particular from 2 to 5 nitrogen atoms in the molecule.

In a preferred embodiment, the invention relates to the use of oligoamines or polyamines of the general formula (I)

Formula I

In the above formula,

R ¹ to R ⁶ radicals each independently represent hydrogen, a C ₁ -C ₃₀ -alkyl group, a C ₅ -C ₈ -cycloalkyl group, a C ₁ -C ₂₉ -alkylcarbonyl group or a C ₂ -C ₈ -cyano Is an alkyl group and R ¹ and R ² and / or R ⁵ and R ⁶ radicals in each case also together with the nitrogen atoms bearing these radicals further hetero atoms (typically nitrogen and / or oxygen and / or sulfur) ) And / or may form a 5- or 6-membered, saturated or unsaturated ring which may have carbonyl atoms and may have further substituents, or in each case together may also be C ₁ -C ₃₀ -alkyl A methylidene moiety which may be substituted with a group and / or a C ₆ -C ₁₂ -aryl group,

The bridging members A ¹ to A ³ are each independently C ₁ -C ₁₂ -alkylene groups and / or C ₆ -C ₁₂ -arylene groups, and the R ¹ and / or R ⁵ radicals in each case also include Together with the nitrogen atom bearing the radical and the carbon atom of the alkylene group A ¹ or A ³ , it may have additional hetero atoms (typically nitrogen and / or oxygen and / or sulfur) and / or carbonyl carbon atoms and further substituents Can form 5- or 6-membered, saturated or unsaturated rings which may have

Variables n and m are integers from 0 to 30, respectively.

Any substituents mentioned in the 5- or 6-membered, saturated or unsaturated rings can be, for example, relatively long or relatively short chain hydrocarbyl radicals, in particular suitable linear or branched alkyl radicals. Useful radicals here are firstly hydrocarbyl radicals having 1 to 30, preferably 1 to 20 carbon atoms, and secondly having 30 to 200, preferably 40 to 100 carbon atoms. Long-chain hydrocarbyl radicals, for example suitable polyisobutenyl radicals.

The oligoamines or polyamines to be used in the context of the present invention are preferably R ¹ to R ⁶ radicals, more preferably having from 1 to 30 carbon atoms, in particular having from 2 to 30 carbon atoms, more preferably Comprises at least one hydrocarbyl radical having 3 to 30 carbon atoms, in particular having 5 to 30 carbon atoms. These relatively long chain hydrocarbyl radicals ensure sufficient fuel solubility. Thus, in a particularly preferred embodiment, the invention relates to a minor proportion of oligoamines or polyamines having one or more such hydrocarbyl radicals having from 5 to 30, in particular from 10 to 22, in particular from 12 to 18 carbon atoms. It is about fuel containing.

Examples of such relatively long chain hydrocarbyl radicals include pure aliphatic linear or branched hydrocarbon radicals, which may be of synthetic or natural origin. Examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl, isobutyl, tert-butyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2- Dimethylpropyl, 1-ethylpropyl, n-hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1- Dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1, 1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, n-heptyl, n-octyl, n-nonyl, isononyl, 2 Ethylhexyl, 2-propylheptyl, n-decyl, n-undecyl, n-dodecyl (lauryl), n-tridecyl, isotridecyl, n-tetradecyl (myristyl), n-pentadecyl, n-hexadecyl (palmityl), n-heptadecyl, n-octadecyl (stearyl), n-nonadecyl and n-eicosyl. Such relatively long-chain hydrocarbyl radicals can also be of the unsaturated type, for example oleyl, linolyl or linolenyl.

Alicyclic hydrocarbyl radicals are also suitable as substituents in aliphatic oligoamines or polyamines in the context of the present invention. Examples thereof include cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, dimethylcyclohexyl, cycloheptyl and cyclooctyl.

Suitable relatively long chain hydrocarbyl radicals are also linear or branched alkylcarbonyl radicals, in particular radicals of corresponding fatty acids having from 5 to 30, in particular from 10 to 22, in particular from 12 to 18 carbon atoms. Examples thereof include formyl, acetyl, n-propanoyl, isopropanoyl, n-butanoyl, 2-butanoyl, isobutanoyl, tert-butanoyl, pentanoyl, 1-methylbutanoyl, 2-methylbutano Noyl, 3-methylbutanoyl, 2,2-dimethylpropanoyl, 1-ethylpropanoyl, n-hexanoyl, 1,1-dimethylpropanoyl, 1,2-dimethylpropanoyl, 1-methyl Pentanoyl, 2-methylpentanoyl, 3-methylpentanoyl, 4-methylpentanoyl, 1,1-dimethylbutanoyl, 1,2-dimethylbutanoyl, 1,3-dimethylbutanoyl, 2,2-dimethyl Butanoyl, 2,3-dimethylbutanoyl, 3,3-dimethylbutanoyl, 1-ethylbutanoyl, 2-ethylbutanoyl, 1,1,2-trimethylpropanoyl, 1,2,2-trimethylpro Panoyl, 1-ethyl-1-methylpropanoyl, 1-ethyl-2-methylpropanoyl, n-heptanoyl, n-octanoyl, n-nonanoyl, isononanoyl, 2-ethylhexa Noyl, 2-propylheptanoyl, n-decanoyl, n-undecanoyl, n-dodecanoyl (lauroyl), n-tridecanoyl, Sotridecanoyl, n-tetradecanoyl (myristoyl), n-pentadecanoyl, n-hexadecanoyl (palmitoyl), n-heptadecanoyl, n-octadecanoyl (stearoyl), n Nonadecanoyl and n-eicosanoyl. Such relatively long chain alkylcarbonyl radicals may also be of the unsaturated type, for example oleoyl, linoloyl or linolenoyl.

Natural raw material sources used in the above-mentioned relatively long-chain aliphatic hydrocarbon radicals or relatively long-chain alkylcarbonyl radicals are in particular vegetable or animal fats or oils, for example coconut oil, tall oil, palm oil, rapeseed oil, soybean oil or jatropha oil. In oligoamines or polyamines having relatively long hydrocarbyl radicals and based on these raw materials, the hydrocarbyl radicals are necessarily present as a homogeneous mixture and / or as a mixture of saturated and unsaturated chains.

The oligoamines or polyamines substituted with the alkylcarbonyl radicals described above are in a simple manner familiar to those skilled in the art from amine bases and reactive derivatives of the corresponding fatty acids such as lower alkyl esters, halides such as fatty acid chlorides or anhydrides. It can manufacture.

The alkylcarbonyl radicals described above in aliphatic oligoamines or polyamines can be converted into the corresponding relatively long chain aliphatic hydrocarbon radicals having the same carbon number, for example, by means of general hydrogenation processes.

Suitable crosslinking members A ¹ to A ³ are in principle all divalent linear or branched aliphatic and divalent aromatic hydrocarbon structures, but polyalkylene groups of the formula-(CH ₂ ) _m -wherein m is 1 to 12, in particular 2 to 6, especially 2 to 4, most preferably 2 or 3). Thus, 1,2-ethylene and 1,3-propylene are particularly suitable. In the case of crosslinking members having two or three carbon atoms, suitable crosslinking members as well as α, ω-bonded hydrocarbon structures are also nonlinear crosslinking members, for example 1,1-ethylene, 1,1-propylene, 2, 2-propylene and 1,2-propylene. Examples of divalent aromatic crosslinking members A ¹ to A ³ are ortho-, meta- and para-phenylene. Crosslinking members A ¹ to A ³ may be the same or different.

The variables n and m are each independently integers 0 to 30, but their upper limit is not critical. n and m are preferably each independently 0-6, in particular 0-4, especially 0-2, most preferably 0 or 1.

In a particularly preferred embodiment, the invention relates to the use of oligoamines or polyamines of general formula (I),

In the above formula,

Each R ¹ to R ⁶ radical is independently hydrogen, a C ₁ -C ₂₂ -alkyl group, a C ₅ -C ₆ -cycloalkyl group or a C ₁ -C ₂₁ -alkylcarbonyl group,

The bridging members A ¹ to A ³ are each independently a C ₂ -C ₃ -alkylene group,

Variables n and m are each 0 or 1,

Provided that at least one of the R ¹ to R ⁶ radicals is a C ₅ -C ₃₀ -alkyl group, in particular a C ₁₀ -C ₂₀ -alkyl group, a C ₅ -C ₆ -cycloalkyl group or a C ₄ -C ₂₉ -alkylcarbonyl Groups, in particular C ₉ -C ₁₉ -alkylcarbonyl groups.

Typical individual examples of such oligoamines or polyamines having relatively short or relatively long chain hydrocarbyl radicals that can be used in the present invention are as follows:

N, N'-dimethyl-1,3-propylenediamine,

N, N'-diethyl-1,3-propylenediamine,

N-isopropyl-1,3-propylenediamine,

N, N'-di-sec-butyl-p-phenylenediamine,

N-dodecyl-1,3-propylenediamine,

N-dodecanoyl-1,3-propylenediamine,

N-tetradecyl-1,3-propylenediamine,

N-tetradecanoyl-1,3-propylenediamine,

N-hexadecyl-1,3-propylenediamine,

N-hexadecanoyl-1,3-propylenediamine,

N-octadecyl-1,3-propylenediamine,

N-octadecanoyl-1,3-propylenediamine,

N-oleyl-1,3-propylenediamine,

N-oleoyl-1,3-propylenediamine,

N-cyclohexyl-1,3-propylenediamine,

N- (3-aminopropyl) cocoamine (main component: N-dodecyl-1,3-propylenediamine),

N- (3-aminopropyl) talamine (main component: N-oleyl-1,3-propylenediamine),

N- (3-aminopropyl) palmamine (main component: N-hexadecyl-1,3-propylene-diamine).

In a further particularly preferred embodiment, the invention relates to the use of oligoamines or polyamines of general formula (I) in which all R ¹ to R ⁶ radicals are hydrogen. Such oligoamines or polyamines are especially unsubstituted oligoalkyleneamines and polyalkyleneamines with linear alkylene bridges. Examples of this are:

1,2-ethylenediamine,

1,3-propylenediamine,

1,4-butylenediamine,

1,6-hexylenediamine,

1,8-octylenediamine,

Diethylenetriamine,

Dipropylenetriamine,

N- (3-aminopropyl) -1,4-butylenediamine,

Triethylenetetramine,

Tripropylenetetramine,

N, N'-bis (3-aminopropylene) -1,2-ethylenediamine,

Tetraethylenepentamine,

Tetrapropylenepentamine,

Pentaethylenehexamine,

Pentapropylenehexamine.

Further examples of representative examples of oligoamines and polyamines of general formula (I) which may be used in the invention are as follows:

N-2-cyanoethyl-N ', N'-dimethyl-1,3-propylenediamine, as a representative example of cyanoalkyl substituted oligoamines or polyamines,

And R ¹ and R ² together with the nitrogen atom to which they have a radical, an oligonucleotide having the R ¹ and R ² radicals form a ring, which may also have additional substituents may or may further have a hetero atom as a representative example of an amine or a polyamine N -(3-amino-2,2-dimethylpropyl) pyrrolidine, N- (3-aminopropyl) pyrazane, N- (3-aminopropyl) morpholine, N- (3-aminopropyl) -N ' Methylpyrazane, N- (3-aminopropyl) -N '-(2-hydroxyethyl) pyrazan and N- (3-aminopropyl) imidazole,

And together with the nitrogen atom having an R ¹ and R ² radicals, carbonyl optionally having a carbonyl carbon atom and an oligonucleotide having the R ¹ and R ² radicals form a ring, which may also have additional substituents as a representative example of an amine or polyamine N- [N ′-(2-amino, preparable by reacting the corresponding polyisobutenylsuccinic anhydride with diethylenetriamine or triethylenetetramine, each having a weight average molecular weight of 1,000 polyisobutenyl radicals Ethyl) -2-aminoethyl)] polyisobutenylsuccinimide and N- [N "-{N '-(2-aminoethyl) -2-aminoethyl} -2-aminoethyl] polyisobutenylsuccinimide ,

As a representative example of oligoamines or polyamines having R ¹ and R ² radicals which are methylidene moieties which may be substituted with alkyl or aryl groups together, the formula Ph—CH═N— (CH ₂ ) ₃ —NH— (CH ₂ ) ₂ N, N'-bis [3- (phenylazametin) propyl] -1,2-ethylenediamine of -NH- (CH ₂ ) ₃ -N = CH-Ph,

Representative examples of oligoamines or polyamines in which the R ¹ radical, together with the nitrogen atom bearing this radical and the carbon atom of the alkylene group A ¹ , may form a 5- or 6-membered ring which may have an additional hetero atom 4- (2-aminoethyl) imidazole as.

Since some of the oligoamines and polyamines described have not been described as components of biofuel oils to date, the present invention also relates to oligoamines of the general formula (I) or polyamines with biofuel oils based on fatty acid esters from 1: 100,000 to Providing a mixture in a weight ratio of 1: 100, preferably 1: 50,000 to 1: 500, especially 1: 20,000 to 1: 1,000, especially 1: 10,000 to 1: 2,000,

In the above formula,

R ¹ to R ⁶ radicals are each independently hydrogen, a C ₁ -C ₃₀ -alkyl group, a C ₅ -C ₈ -cycloalkyl group or a C ₂ -C ₈ -cyanoalkyl group, R ¹ and R ² and / Or the R ⁵ and R ⁶ radicals in each case together with the nitrogen atom bearing these radicals form a five or six membered, saturated or unsaturated ring which may have additional heteroatoms and which may have further substituents; Or a methylidene moiety which in each case may also be substituted together with a C ₁ -C ₃₀ -alkyl group and / or a C ₆ -C ₁₂ -aryl group,

The bridging members A ¹ to A ³ are each independently C ₁ -C ₁₂ -alkylene groups and / or C ₆ -C ₁₂ -arylene groups, and the R ¹ and / or R ⁵ radicals in each case also include Together with the nitrogen atom bearing the radical and the carbon atom of the alkylene group A ¹ or A ³ , 5- or 6-membered, which may have additional hetero atoms and / or carbonyl carbon atoms and may bear further substituents, saturated or Can form unsaturated rings,

Variables n and m are integers from 0 to 30, respectively.

Some of the oligoamines and polyamines described have not been described to date as components of fuel oils consisting of biofuel oils and conventional intermediate distillates, so the present invention also provides

(A) 0.1 to 75% by weight of one or more biofuel oils based on fatty acid esters, and

(B) 25 to 99.9% by weight of intermediate distillates of fossil origin and / or vegetable and / or animal origin, predominantly hydrocarbon mixtures and free of fatty acid esters

A large proportion of fuel oil, and

Minor proportions of one or more oligoamines or polyamines of general formula (I)

Providing fuel, including

In the above formula,

R ¹ to R ⁶ radicals are each independently hydrogen, a C ₁ -C ₃₀ -alkyl group, a C ₅ -C ₈ -cycloalkyl group or a C ₂ -C ₈ -cyanoalkyl group, R ¹ and R ² and / Or the R ⁵ and R ⁶ radicals in each case together with the nitrogen atom bearing these radicals form a five or six membered, saturated or unsaturated ring which may have additional heteroatoms and which may have further substituents; Or a methylidene moiety which in each case may also be substituted together with a C ₁ -C ₃₀ -alkyl group and / or a C ₆ -C ₁₂ -aryl group,

The bridging members A ¹ to A ³ are each independently C ₁ -C ₁₂ -alkylene groups and / or C ₆ -C ₁₂ -arylene groups, and the R ¹ and / or R ⁵ radicals in each case also include Together with the nitrogen atom bearing the radical and the carbon atom of the alkylene group A ¹ or A ³ , 5- or 6-membered, which may have additional hetero atoms and / or carbonyl carbon atoms and may bear further substituents, saturated or Can form unsaturated rings,

Variables n and m are integers from 0 to 30, respectively.

The fuel component (A) is also commonly referred to as "biodiesel". Such biofuel oils (A) preferably comprise mainly alkyl esters of fatty acids derived from vegetable and / or animal oils and / or fats. Alkyl esters typically contain glycerides, especially triglycerides, which arise from vegetable and / or animal oils and / or fats, and lower alcohols such as ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butan It is understood to mean lower alkyl esters, in particular C ₁ -C ₄ -alkyl esters, obtainable by transesterification with knol, tert-butanol or in particular methanol (“FAME”: fatty acid methyl ester).

Examples of vegetable oils that can be converted to the corresponding alkyl esters and thus can serve as the basis of biodiesel include castor oil, olive oil, peanut oil, palm kernel oil, coconut oil, mustard oil, cottonseed oil, in particular sunflower oil, palm oil, soybean oil and There is rapeseed oil. Further examples include oils obtained from wheat, jute, sesame and cherries. In addition, peanut oil, jatropha oil and cottonseed oil can be used. Extraction of such oils and their conversion to alkyl esters can be known from or derived from the prior art.

In addition, vegetable oils that have already been used, for example used deep fat fryer oils, can be converted into alkyl esters, where appropriate after appropriate washing, so that they can serve as the basis for biodiesel.

Similarly, vegetable fats can in principle be used as a source for biodiesel, but play a small role.

Examples of animal fats and oils that can be converted to the corresponding alkyl esters and thus function as the basis of biodiesel are similar fats and oils obtained as waste in the slaughter or use of fish oil, tallow, pork and farm animals or wildlife.

Saturated or unsaturated fatty acids which are based on the mentioned vegetable and / or animal oils and / or fats, which generally have from 12 to 22 carbon atoms and may carry additional functional groups such as hydroxyl groups, are particularly Uric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, elideic acid, erucic acid and ricinoleic acid, in particular in the form of mixtures of these fatty acids.

Typical lower alkyl esters based on vegetable and / or animal oils and / or fats used as biodiesel or biodiesel components include, for example, sunflower methyl esters, palm oil methyl esters ("PME"), soybean oil methyl esters ( "SME"), in particular rapeseed oil methyl ester ("RME").

However, it is also possible to use monoglycerides, diglycerides, in particular triglycerides per se, for example castor oil, or mixtures of these glycerides as components for biodiesel or biodiesel.

In the context of the present invention, fuel component (B) is to be understood as meaning an intermediate distillate fuel boiling in the range from 120 to 450 ° C. Such middle distillate fuels are used in particular as diesel fuels, heating oils or kerosene, with diesel fuels and heating oils being particularly preferred.

Middle distillate fuel refers to a fuel obtained by distilling crude oil and boiling in the range of 120 to 450 ° C. Preference is given to using low sulfur intermediate distillates, ie less than 350 ppm sulfur, in particular less than 200 ppm sulfur, in particular less than 50 ppm sulfur. In special cases, the middle distillate fuel contains less than 10 ppm sulfur. This middle distillate is also referred to as "sulfur free". Intermediate distillate fuels are crude crude distillates which are generally refined under hydrogenation conditions and thus contain only minor proportions of polyaromatic and polar compounds. The middle distillate fuel is preferably an intermediate distillate having a 95% distillation point below 370 ° C., in particular below 350 ° C., in particular cases below 330 ° C.

Low and sulfur free intermediate distillates can be obtained from relatively heavy crude oil fractions which cannot be distilled under atmospheric pressure. Typical conversion processes for producing intermediate distillates from heavy crude oil fractions include hydrocracking, thermal cracking, catalytic cracking, coking processes and / or visbreaking. It includes. Depending on the process, these intermediate distillates are obtained in low sulfur or sulfurless form, or are purified under hydrogenation conditions.

The middle distillate preferably has an aromatic content of less than 28% by weight, in particular less than 20% by weight. The content of general paraffin is 5% to 50% by weight, preferably 10% to 35% by weight.

In addition, an intermediate distillate, referred to as fuel component (B), may be indirectly derived from a fossil source, for example mineral oil or natural gas, or otherwise prepared from biomass through gasification and subsequent hydrogenation. It is to be understood as meaning an intermediate distillate. Typical examples of intermediate distillate fuels derived indirectly from fossil sources are GTL ("gas-to-liquid") diesel fuels obtained by Fischer-Tropsch synthesis. The middle distillate is prepared from biomass, for example via a BTL ("bio-to-liquid") process, and can be used alone or as a mixture with other intermediate distillates as fuel component (B). Can be. In addition, intermediate distillates include hydrocarbons obtained by hydrogenation of fats and fatty oils. The middle distillate mainly contains n-paraffins. It is common for the intermediate distillate fuels mentioned that the middle distillate is mainly a hydrocarbon mixture and does not contain fatty acid esters.

The quality of heating oils and diesel fuels is better described, for example, in DIN 51603 and EN 590 (see also Ullmann's Encyclopedia of Industrial Chemistry, 5th edition, volume A12, p. 617 ff.), Which is expressly incorporated herein by reference. It is described in detail.

In addition, the described fuels generally contain additives customary to this, such as flow modifiers to improve low temperature performance, in particular cold flow modifiers ("medium distillate flow improvers"), nucleators, paraffin dispersants ("wax precipitation"). Prevention additives ") and mixtures thereof, and also conductive improvers, corrosion protection additives, lubricating additives, antioxidants, metal deactivators, antifoams, oil separators, detergents, cetane number improvers, solvents or diluents, dyes or flavors or mixtures thereof Include.

In particular due to the olefinically unsaturated fatty acid units present in the biofuel oil of the fuel component (A), the biofuel oil is in pure form and also intermediate of the fuel component (B) when unstable to atmospheric oxygen and no suitable precautions are taken. The mixture with distillate is gradually degraded by oxidation during its storage. The addition of conventional antioxidants such as sterically hindered phenols such as BHT, BHA or TBHQ has not been found to be effective enough even at relatively high doses. However, the oligoamines or polyamines described above fulfill this purpose as antioxidants which have been improved in a successful manner. In addition, the oligoamines or polyamines described above generally have better solubility in biofuel oils and in corresponding fuels including biofuel oils.

A useful method for measuring the oxidative stability of biofuel oils such as FAME is that the air stream passes through the biofuel oil under controlled conditions at relatively high temperatures (110 ° C.) and volatile acid adducts formed in the oxidation are collected and the conductivity method It was found to be the so-called Rancimat method according to European Standard 14 112 which is analyzed by. The longer the induction time (incubation time) measured to rise in the conductivity curve, the more stable the biofuel is. The desired value for the induction time is more than 7 hours, in particular more than 8 hours, in particular more than 10 hours, and a minimum dose of antioxidant is used. Most biofuels have an induction time of less than 7 hours by default. In the case of biofuel oils and also in the case of mixtures of biofuel oils with conventional intermediate distillates of fossil origin, the induction time is significantly extended by the described oligoamines or polyamines. There is interest in the minimum dose of antioxidants to save cost and to limit the risk of interaction with other active ingredients in biofuel oils or fuels.

The oligoamines or polyamines described are added in the fuels of the invention typically in amounts of 10 to 10,000 ppm by weight, based on the amount of biofuel (A). Preferred dosage ranges are from 20 to 2,000 ppm by weight, in particular from 50 to 1,000 ppm by weight, in particular from 100 to 500 ppm by weight. Most of the oligoamines or polyamines described even meet the requirement for long induction times in lancimet tests with doses of up to 500 ppm by weight.

Conventional antioxidants, in particular sterically hindered phenols such as BHT, BHA, TBHQ, trimethylhydroquinone or bisphenol A, are preferably described in a weight ratio of 10: 1 to 1:10, especially 3: 1 to 1: 3. A mixture of oligoamines or polyamines can further increase antioxidant activity and therefore increase stabilization in biofuel oils.

For the doses of oligoamines or polyamines described in biofuel oil or for fuel, many of the oligoamines or polyamines mentioned are solid or waxy materials, so it is advantageous to dissolve the amine in a solvent in advance so that a liquid dose is possible in each case. It turned out. Suitable solvents in this regard are in particular alcohols, for example n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, 2-ethylhexanol or 2-propylheptanol , Carboxylic acid esters or fatty acid esters, for example rapeseed oil methyl esters, or amines such as dimethylamine, trimethylamine, piperidine or morpholine.

The aliphatic oligoamines or polyamines described are sufficiently prepared because of the simple manner of preparations familiar to those skilled in the art, in particular, trace amounts of metals in the fuel can easily cause defects in the engine and downstream of any exhaust gas catalytic converter system connections. It can be used in its pure form, ie mainly free of trace metals such as iron, sodium or potassium.

The examples described below are intended to illustrate the invention without limiting the invention.

In the case of oligoamines described below as antioxidants, the induction time [in hours] in pure biofuel oils and in mixtures of biofuel oils with conventional intermediate distillates of fossil origin is the lancimet test according to European Standard 14 112. Measured as a function of capacity

Oligoamines Used:

"A1" = tetraethylenepentamine,

"A2" = diethylenetriamine,

"A3" = N- (3-aminopropyl) -1,4-butylenediamine,

"A4" = N- (3-aminopropyl) -N'-methylpyrazane,

"A5" = N- (3-aminopropyl) cocoamine,

"A6" = N- (3-aminopropyl) palmamine,

"A7" = N-oleyl-1,3-propylenediamine,

"A8" = N-cyclohexyl-1,3-propylenediamine,

"A9" = N- (3-aminopropyl) imidazole,

"A10" = N-2-cyanoethyl-N ', N'-dimethyl-1,3-propylenediamine,

"A11" = N, N'-bis [3- (phenylazametin) propyl] -1,2-ethylenediamine,

"A12" = 4- (2-aminoethyl) imidazole,

"A13" = N- (3-amino-2,2-dimethylpropyl) pyrrolidine.

Prior art antioxidants used for comparison:

"BHT" = 2,6-di-tert-butyl-4-methylphenol

Fuel Oil Used:

"B1" = commercial rapeseed oil methyl ester (Camp-Biodiesel, Ohsenfurt),

"B2" = a mixture of 50 vol% B1 and 50 vol% commercial diesel fuel of fossil origin.

The table below shows the measurement results:

Example number Remarks Biofuel Oil Antioxidant Capacity [Weight ppm] Induction time [h] Default value B1 radish 0 6.3 C1 compare B1 BHT 200 7.5 One The present invention B1 A1 200 13.3 2 The present invention B1 A2 200 10.7 3 The present invention B1 A3 200 11.6 4 The present invention B1 A4 200 10.3 C2 compare B1 BHT 1000 7.9 5 The present invention B1 A5 1000 16.7 6 The present invention B1 A6 1000 11.5 7 The present invention B1 A7 1000 16.8 8 The present invention B1 A8 1000 10.1 9 The present invention B1 A9 1000 11.9 10 The present invention B1 A10 1000 11.3 11 The present invention B1 A11 1000 17.4 12 The present invention B1 A12 1000 18.7 13 The present invention B1 A13 1000 11.4 Default value B2 radish 0 10.9 V3 compare B2 BHT 200 15.1 13 The present invention B2 A1 200 > 24 14 The present invention B2 A2 200 18.6 15 The present invention B2 A3 200 > 24 16 The present invention B2 A4 200 > 24

Doses are each based on the active substance. The additive is metered as a 10 wt% solution in 2-ethylhexanol.

Claims (8)

Oxidation of biofuel oils based on fatty acid esters, or mixtures of such biofuel oils with fossil origin and / or middle distillate of vegetable and / or animal origin, predominantly hydrocarbon mixtures and free of fatty acid esters Use of oligoamines or polyamines having a number average molecular weight of 46 to 70,000 and containing no phenolic hydroxyl groups to increase stability. Use of an oligoamine or polyamine of the general formula Formula I

In the above formula, R ¹ to R ⁶ radicals each independently represent hydrogen, a C ₁ -C ₃₀ -alkyl group, a C ₅ -C ₈ -cycloalkyl group, a C ₁ -C ₂₉ -alkylcarbonyl group or a C ₂ -C ₈ -cyano Alkyl groups, and the R ¹ and R ² and / or R ⁵ and R ⁶ radicals in each case may also have additional hetero atoms and / or carbonyl carbon atoms together with the nitrogen atoms bearing these radicals 5- or 6-membered, which may bear a substituent, may form a saturated or unsaturated ring, or in each case also together, are substituted with a C ₁ -C ₃₀ -alkyl group and / or a C ₆ -C ₁₂ -aryl group May be a methylidene moiety, The bridging members A ¹ to A ³ are each independently C ₁ -C ₁₂ -alkylene groups and / or C ₆ -C ₁₂ -arylene groups, and the R ¹ and / or R ⁵ radicals in each case also include Together with the nitrogen atom bearing the radical and the carbon atom of the alkylene group A ¹ or A ³ , 5- or 6-membered, which may have additional hetero atoms and / or carbonyl carbon atoms and may bear further substituents, saturated or Can form unsaturated rings, Variables n and m are integers from 0 to 30, respectively. 3. Use of oligoamines or polyamines of general formula (I) according to claim 2, having at least one hydrocarbyl radical having 1 to 30 carbon atoms as R ¹ to R ⁶ radicals. The method of claim 3, Each R ¹ to R ⁶ radical is independently hydrogen, a C ₁ -C ₂₂ -alkyl group, a C ₅ -C ₆ -cycloalkyl group or a C ₁ -C ₂₁ -alkylcarbonyl group, The bridging members A ¹ to A ³ are each independently a C ₂ -C ₃ -alkylene group, Variables n and m are each 0 or 1, Provided that at least one of the R ¹ to R ⁶ radicals is a C ₅ -C ₃₀ -alkyl group, a C ₅ -C ₆ -cycloalkyl group or a C ₄ -C ₂₉ -alkylcarbonyl group Use of oligoamines or polyamines of general formula (I). 3. Use of oligoamines or polyamines of general formula (I) according to claim 2, wherein all R ¹ to R ⁶ radicals are hydrogen. 6. Use of an oligoamine or polyamine according to any one of claims 1 to 5 in an amount of from 10 to 10,000 ppm by weight, based on the amount of biofuel oil. A mixture of weight ratios of from 1: 100,000 to 1: 100 with an oligoamine or polyamine of general formula (I) and a biofuel oil based on fatty acid esters: In the above formula, R ¹ to R ⁶ radicals are each independently hydrogen, a C ₁ -C ₃₀ -alkyl group, a C ₅ -C ₈ -cycloalkyl group or a C ₂ -C ₈ -cyanoalkyl group, R ¹ and R ² and / Or the R ⁵ and R ⁶ radicals in each case together with the nitrogen atom bearing these radicals form a five or six membered, saturated or unsaturated ring which may have additional heteroatoms and which may have further substituents; Or a methylidene moiety which in each case may also be substituted together with a C ₁ -C ₃₀ -alkyl group and / or a C ₆ -C ₁₂ -aryl group, The bridging members A ¹ to A ³ are each independently C ₁ -C ₁₂ -alkylene groups and / or C ₆ -C ₁₂ -arylene groups, and the R ¹ and / or R ⁵ radicals in each case also include Together with the nitrogen atom bearing the radical and the carbon atom of the alkylene group A ¹ or A ³ , 5- or 6-membered, which may have additional hetero atoms and / or carbonyl carbon atoms and may bear further substituents, saturated or Can form unsaturated rings, Variables n and m are integers from 0 to 30, respectively. (A) 0.1 to 75% by weight of one or more biofuel oils based on fatty acid esters, and (B) 25 to 99.9% by weight of intermediate distillates of fossil origin and / or vegetable and / or animal origin, predominantly hydrocarbon mixtures and free of fatty acid esters A large proportion of fuel oil, and Minor proportions of one or more oligoamines or polyamines of general formula (I) Fuel Containing: In the above formula, R ¹ to R ⁶ radicals are each independently hydrogen, a C ₁ -C ₃₀ -alkyl group, a C ₅ -C ₈ -cycloalkyl group or a C ₂ -C ₈ -cyanoalkyl group, R ¹ and R ² and / Or the R ⁵ and R ⁶ radicals in each case together with the nitrogen atom bearing these radicals form a five or six membered, saturated or unsaturated ring which may have additional heteroatoms and which may have further substituents; Or a methylidene moiety which in each case may also be substituted together with a C ₁ -C ₃₀ -alkyl group and / or a C ₆ -C ₁₂ -aryl group, The bridging members A ¹ to A ³ are each independently C ₁ -C ₁₂ -alkylene groups and / or C ₆ -C ₁₂ -arylene groups, and the R ¹ and / or R ⁵ radicals in each case also include Together with the nitrogen atom bearing the radical and the carbon atom of the alkylene group A ¹ or A ³ , 5- or 6-membered, which may have additional hetero atoms and / or carbonyl carbon atoms and may bear further substituents, saturated or Can form unsaturated rings, Variables n and m are integers from 0 to 30, respectively.