KR20050117567A - Diesel fuel composition and a method to improve filterability of diesel fuel - Google Patents

Abstract

Disclosed is a stabilized diesel fuel composition comprising a) a diesel fuel with a cetane number less than or equal to 50, b) an effective amount of at least one compound selected from the group consisting of the cetane improvers and c) i) an effective stabilizing amount of at least one compound selected from the group consisting of the stable nitroxide compounds or ii) an effective synergistic stabilizing amount of at least one compound selected from the group consisting of the stable nitroxide compounds and at least one antioxidant compound selected from the group consisting of the aromatic amine antioxidants and the hindered phenolic antioxidants. The cetane improvers are for example nitrate esters. The diesel fuel compositions exhibit improved filterability.

Description

Diesel fuel composition and a method to improve filterability of diesel fuel

The present invention relates to a stabilized diesel fuel composition comprising a cetane enhancer. Stabilized diesel fuel compositions exhibit improved filterability. The diesel fuel composition comprises a stable nitroxide compound and optionally a stabilizer selected from the group consisting of aromatic amines and hindered phenolic antioxidants. Cetane enhancers are for example nitrate esters. The composition of the present invention reduces the formation of insoluble materials that can clog fuel lines and filters.

Diesel fuel is the second most commonly used fuel in internal combustion engines. It is widely used in marine and land applications as well as trucks, buses and heavy equipment. It is also increasingly used in passenger cars because of the higher fuel efficiency of compression ignition engines compared to spark ignition engines.

In diesel engines, fuel is ignited during the compression stroke by heat generated by the compression of air in the cylinders. There is a period between when fuel is injected into the cylinder and when heat-compressed combustion burns the fuel. This period is known as ignition delay, and if it is too long, diesel knock may occur. Other effects of long ignition delays are incomplete combustion, which leads to power loss, increased carbon monoxide production and increased hydrocarbons and particulates in the exhaust. Recently, there has been pressure from regulators to reduce these environmental pollutants.

The cetane number is how well a particular fuel works in a compressed ignition engine. Poor fuel with a long ignition delay has a low cetane number, while a good fuel has a high cetane number. Typical values for commercially available denitrified fuels are 40-48 and above 50 are considered the highest end. Higher cetane number fuels can reduce engine deposits as well as environmental benefits and facilitate starting at cold temperatures.

Due to the increasing demand, the use of decomposed materials of diesel fuel is increasing. Unfortunately, catalytic crakers, hydrocrackers and coker distillates have low cetane numbers. In some cases, the cetane number is less than 40, which is the lowest cetane number allowed for diesel fuel requirements. Additives known as cetane enhancers have been developed to increase the cetane number of diesel fuels to an acceptable level.

Nitrate ester cetane enhancers are described in US Pat. Nos. 4,705,534, 5,258,049 and 5,482,518.

Cetane enhancers can destabilize diesel fuel. Typical Thermal Stability Test In ASTM D6468, diesel fuel is aged at 150 ° C. (302 ° F.) for 1.5 or 3.0 hours. Under these conditions, a thermally stable low cetane number fuel will produce very little deposits. Adding commercially available cetane enhancers such as 2-ethylhexyl nitrate will increase fuel quality for combustion but will result in more deposits in thermal stability tests. In a real engine, these deposits can result in clogging of the fuel lines and fuel filters.

EP-A-0947577 discloses a fuel composition comprising a cetane enhancer and a tert-alkyl amine thermal stabilizer. US published application 2002/0026743 discloses the use of heterocycles with large hydrocarbyl groups such as polyisobutenyl succinimide to increase the thermal stability of cetane enhancers in fuel compositions.

Despite efforts to prevent the formation of insoluble materials caused by cetane enhancers, there is a need to stabilize diesel fuels more effectively. This need is strongly requested for fuels that are more sensitive to the harmful effects of cetane enhancers.

Surprisingly, it has been found that hindered nitroxide stabilizers are particularly suitable as additives to increase the thermal stability of diesel fuels containing cetane enhancers. This hindered nitroxide stabilizer acts to reduce the formation of insoluble matter (or deposits) in the diesel fuel, thereby increasing the filterability of the fuel filter and preventing clogging of the fuel filter.

U. S. Patent No. 5,711, 767 discloses the use of stable nitroxide compounds to reduce gum formation in gasoline. U. S. Patent No. 5,460, 634 discloses the use of stable nitroxide compounds to reduce emissions produced by combustion of fuels.

The present invention,

a) diesel fuel having a cetane number of 50 or less;

b) an effective amount of at least one compound selected from the group consisting of cetane enhancers; And

c) at least one compound stabilizing effective amount selected from the group consisting of i) stable nitroxide compounds, or

ii) a stabilized diesel fuel composition comprising at least one compound selected from the group consisting of stable nitroxide compounds and at least one antioxidant compound synergistically stabilizing effective amount selected from the group consisting of aromatic amine antioxidants and hindered phenolic antioxidants It is about.

Additional combinations of stable nitroxides and antioxidants of component c) have synergism to provide thermal stability.

Diesel fuel is present as the main component present in an amount exceeding 50% by weight of the total formulation.

Hydrocarbon-based diesel fuels are typically included in a mixture of hydrocarbons having a diesel fuel boiling point range of about 160 ° C. to about 370 ° C., such as 90% distillation point between 282 ° C. and 338 ° C. (ASTM D-396 and D-975). These diesel fuels have a minimum flame temperature of 38 ° C. Diesel fuel is a medium distillate fuel because it contains a fraction that is distilled after gasoline. The diesel fuel of the present invention has a low sulfur content and has sulfur of 500 ppm or less / weight, such as 100 ppm / weight or 60 ppm or less / weight. The aromatic content is 15-50% by volume, such as about 10-35% by volume. Low sulfur content results in lower aromatics.

Typical cetane numbers for commercial diesel fuels are 40-48. The cetane number of the diesel fuel of the present invention is less than 50. That is, the diesel fuel of the present invention has an original cetane number of less than 50 (before adding the cetane enhancer).

Cetane enhancers are for example peroxides, such as di-tert-butylperoxide, thioaldehydes, tert-alkyl primary amines, perketal as described in US Pat. No. 5,011,503, alkylether / as described in US Pat. No. 5,520,710. Peroxide mixtures, peracids as described in EP-A-0537931, tetrazole and triazoles as described in U.S. Pat. Side, organic nitrate and salts thereof.

Cetane enhancers are especially organic nitrates such as nitrate esters or alkyl nitrates. Nitrate ester cetane enhancers are described in US Pat. Nos. 4,705,534, 5,258,049 and 5,482,518, the contents of which are incorporated herein by reference.

Nitrate esters are, for example, hydrocarbyl nitrates, wherein hydrocarbyl is a straight or branched chain alkyl having 1 to 24 carbon atoms, a straight or branched chain having 2 to 24 carbon atoms containing 1 to 3 oxygen atoms in the middle Alkyl, straight or branched alkenyl having 3 to 24 carbon atoms, cycloalkyl having 5 to 12 carbon atoms or C ₁ -C ₄ alkyl-substituted cycloalkyl having 5 to 12 carbon atoms.

Examples of hydrocarbyl are methyl, ethyl, n-propyl, isopropyl, butyl, amyl, hexyl, heptyl, octyl, isooctyl, 2-ethylhexyl, nonyl, decyl, allyl, cyclopentyl, cyclohexyl, methylcyclohexyl , Cyclododecyl, 2-ethoxyethyl and 2- (2-ethoxyethoxy) ethyl.

Preferred nitrate esters are, for example, 2-ethylhexyl nitrate.

Nitroxides of the invention are described, for example, in US Pat. Nos. 5,711,767 and 5,460,634, which are incorporated herein by reference.

Nitroxide can be of several different kinds. Aromatic and aliphatic (often hindered amine) nitroxides have been shown to be effective in the composition of the present invention. Particularly useful are hindered amine nitroxides, ie compounds in which two tertiary carbon atoms have adjacent nitroxy moieties. Adjacent tertiary carbon atoms are linked by various bridge groups to form cyclic structures such as 6-membered piperidine, piperazine, 5-membered pyrrolidone and the like.

Nitroxide stabilizers useful in the present invention include

Or

Compounds containing at least one group of:

In the food,

Each R is, independently from each other, methyl or ethyl, and

T is the group necessary to complete the 5- or 6-membered ring.

Two or more nitroxide groups may be present in the same molecule linked via a T residue as shown in the following formula:

Wherein E is a linking group.

Stable nitroxide compounds are for example bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 4-hydroxy-1-oxyl-2,2,6,6 Tetramethylpiperidine, 4-ethoxy-1-oxyl-2,2,6,6-tetramethylpiperidine, 4-propoxy-1-oxy-2,2,6,6-tetramethylpi Ferridine, 4-acetamido-1-oxyl-2,2,6,6-tetramethylpiperidine, 1-oxyl-2,2,6,6-tetramethylpiperidine, 1-oxyl-2 , 2,6,6-tetramethylpiperidin-4-one, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-acetate, 1-oxyl-2,2,6 , 6-tetramethylpiperidin-4-yl 2-ethylhexanoate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl stearate, 1-oxyl-2,2 , 6,6-tetramethylpiperidin-4-yl benzoate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butyl-benzoate, bis (1 -Oxyl-2,2,6,6-tetramethylpiperidin-4-yl) succinate, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipate , Bis (1- Sil-2,2,6,6-tetramethylpiperidin-4-yl) n-butylmalonate, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) Phthalate, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) isophthalate, bis (1-oxyl-2,2,6,6-tetramethylpiperidine-4 -Yl) terephthalate, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate, N, N'-bis (1-oxyl-2,2, 6,6-tetramethylpiperidin-4-yl) adipamide, N- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) caprolactam, N- (1 -Oxyl-2,2,6,6-tetramethylpiperidin-4-yl) dodecylsuccinimide, 2,4,6-tris- [N-butyl-N- (1-oxyl-2,2 , 6,6-tetramethylpiperidin-4-yl)] s-triazine, 4,4'-ethylenebis (1-oxyl-2,2,6,6-tetramethylpiperazin-3-one) , 2-oxyl-1,1,3,3-tetramethyl-2-isobenzazole, 1-oxyl-2,2,5,5-tetramethylpyrrolidone, N, N-bis (1,1, 3,3-tetramethylbutyl) nitroxide, N, N-diphenylnitroxyl, Mono- and dialkylated tert-butyl / tert-octyl-N, N-diphenylnitroxyl and mono- and dialkylated nonyl-N, N-diphenylnitroxyl.

Stable nitroxide compounds are for example bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 4-hydroxy-1-oxyl-2,2,6,6 Tetramethylpiperidine, 4-ethoxy-1-oxyl-2,2,6,6-tetramethylpiperidine, 4-propoxy-1-oxyl-2,2,6,6-tetramethylpi Ferridine, 4-acetamido-1-oxyl-2,2,6,6-tetramethylpiperidine, 1-oxyl-2,2,6,6-tetramethylpiperidine or 1-oxyl-2 , 2,6,6-tetramethylpiperidin-4-one.

The nitroxide compound is bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate or 4-hydroxy-1-oxyl-2,2,6,6-tetra Particular embodiments are preferred that are methylpiperidine.

Aromatic amine antioxidants include, for example, 4- (p-toluene-sulfamoyl) diphenylamine, diphenylamine, N-allyldiphenylamine, 4-isopropoxydiphenylamine, N-phenyl-1-naphthylamine, N- (4-tert-octylphenyl) -1-naphthylamine, N-phenyl-2-naphthylamine, octylated diphenylamines such as 4,4'-di-tert-octyldiphenylamine, 4 -n-butylaminophenol, 4-butyrylaminophenol, 4-nonanoylamidophenol, 4-dodecanoylaminophenol, 4-octadecanoylaminophenol, bis (4-methoxyphenyl) amine, 2 , 6-di-tert-butyl-4-dimethylaminomethylphenol, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, N, N, N ', N'-tetramethyl -4,4'-diaminodiphenylmethane, 1,2-bis [(2-methylphenyl) amino] ethane, 1,2-bis (phenylamino) propane, (o-tolyl) biguanide, bis [4 A mixture of-(1 ', 3'-dimethylbutyl) phenyl] amine, tert-octylated N-phenyl-1-naphthylamine, mono- and dialkylated tert-butyl / tert-octyl-diphenylamine , Mixtures of mono- and dialkylated nonylphenylamines, mixtures of mono- and dialkylated dodecyldiphenylamines, mixtures of mono- and dialkylated isopropyl / isohexyldiphenyl, mono- and dialkylated tert- Mixtures of butyldiphenylamine, 2,3-dihydro-3,3-dimethyl-4H-1,4-benzothiazine, phenothiazine, mono- and dialkylated tert-butyl / tert-octylphenolthiazine Mixtures, mixtures of mono- and dialkylated tert-octyl-phenothiazines, N-allylphenothiazines, N, N, N ', N'-tetraphenyl-1,4-diaminobut-2-enes, Phenylenediamine and N, N'-di-sec-butyl-phenylenediamine.

The hindered phenolic antioxidants are selected from the group consisting of:

Alkylated monophenols such as 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di- tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl- 4-methylphenol, 2- (α-methylcyclohexyl) -4,6-dimethylphenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6- Di-tert-butyl-4-methoxymethylphenol, nonylphenol linear or branched from side chains such as 2,6-di-nonyl-4-methylphenol, 2,4-dimethyl-6- (1-methylundec -1-yl) phenol, 2,4-dimethyl-6- (1-methylheptadec-1-yl) phenol, 2,4-dimethyl-6- (1-methyltridec-1-yl) phenol or these Mixture of;

Alkylthiomethylphenols such as 2,4-di-octylthiomethyl-6-tert-butylphenol, 2,4-di-octylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethyl Phenol or 2,6-di-dodecylthiomethyl-4-nonylphenol;

Hindered hydroquinones such as 2,6-di-tert-butyl-4-methoxyphenol, 2,5-di-tert-butyl-hydroquinone, 2,5-di-tert-amylhydroquinone, 2,6- Diphenyl-4-octadecyloxyphenol, 2,6-di-tert-butyl-hydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4 -Hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenyl stearate or bis (3,5-di-tert-butyl-4-hydroxyphenyl) adipate;

Tocopherols such as α-tocophenol, β-tocophenol, γ-tocophenol, δ-tocophenol or mixtures thereof (vitamin E);

Hydroxylated thiodiphenyl ethers such as 2,2'-thiobis (6-tert-butyl-4-methylphenol), 2,2'-thiobis (4-octylphenol), 4,4'- Thiobis (6-tert-butyl-3-methylphenol), 4,4'-thiobis (6-tert-butyl-2-methylphenol), 4,4'-thiobis (3,6-di-secondary Amylphenol) or 4,4'-bis (2,6-dimethyl-4-hydroxyphenyl) disulfide;

Alkylidenebisphenols such as 2,2'-methylenebis (6-tert-butyl-4-methylphenol), 2,2'-methylenebis (6-tert-butyl-4-ethylphenol), 2,2 '-Methylenebis [4-methyl-6- (α-methylcyclohexyl) -phenol], 2,2'-methylenebis (4-methyl-6-cyclohexylphenol), 2,2'-methylenebis (6 -Nonyl-4-methylphenol), 2,2'-methylenebis (4,6-di-tert-butylphenol), 2,2'-ethylidenebis (4,6-di-tert-butylphenol), 2,2'-ethylidenebis (6-tert-butyl-4-isobutylphenol), 2,2'-methylenebis [6- (α-methylbenzyl) -4-nonylphenol], 2,2'- Methylenebis [6- (α, α-dimethylbenzyl) -4-nonylphenol], 4,4'-methylenebis (2,6-di-tert-butylphenol), 4,4'-methylenebis (6- tert-butyl-2-methylphenol), 1,1-bis (5-tert-butyl-4-hydroxy-2-methylphenyl) butane, 2,6-bis (3-tert-butyl-5-methyl-2 -Hydroxybenzyl) -4-methylphenol, 1,1,3-tris (5-tert-butyl-4-hydroxy-2-methylphenyl) butane, 1,1-bis (5-tert-butyl-4- Hydroxy-2-methyl-phenyl) -3-n-dodecylmercaptobutane, ethylene Recalled bis [3,3-bis (3'-tert-butyl-4'-hydroxyphenyl) butyrate], bis (3-tert-butyl-4-hydroxy-5-methyl-phenyl) dicyclopentadiene, Bis [2- (3'-tert-butyl-2'-hydroxy-5'-methylbenzyl) -6-tert-butyl-4-methylphenyl] terephthalate, 1,1-bis- (3,5-dimethyl 2-hydroxyphenyl) butane, 2,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) -propane, 2,2-bis (5-tert-butyl-4-hydroxy 2-methylphenyl) -4-n-dodecylmercaptobutane or 1,1,5,5-tetra (5-tert-butyl-4-hydroxy-2-methylphenyl) pentane;

O-, N- and S-benzyl compounds, for example 3,5,3 ', 5'-tetra-tert-butyl-4,4'-dihydroxy-dibenzyl ether, octadecyl-4-hydroxy -3,5-dimethylbenzyl mercaptoacetate, tridecyl-4-hydroxy-3,5-di-tert-butylbenzyl mercaptoacetate, tris (3,5-di-tert-butyl-4-hydroxybenzyl ) Amine, bis (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) dithioterephthalate, bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide or iso Octyl-3,5-di-tert-butyl-4-hydroxybenzyl mercaptoacetate;

Hydroxybenzylated malonates, for example dioctadecyl-2,2-bis (3,5-di-tert-butyl-2-hydroxybenzyl) malonate, di-octadecyl-2- (3-tert -Butyl-4-hydroxy-5-methylbenzyl) -malonate, di-dodecylmercaptoethyl-2,2-bis (3,5-di-tert-butyl-4-hydroxybenzyl) malonate or bis -[4- (1,1,3,3-tetramethylbutyl) phenyl] -2,2-bis (3,5-di-tert-butyl-4-hydroxybenzyl) malonate;

Aromatic hydroxybenzyl compounds such as 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -2,4,6-trimethylbenzene, 1,4-bis (3 , 5-di-tert-butyl-4-hydroxybenzyl) -2,3,5,6-tetramethylbenzene or 2,4,6-tris (3,5-di-tert-butyl-4-hydroxy Benzyl) phenol;

Triazine compounds such as 2,4-bis (octylmercapto) -6- (3,5-di-tert-butyl-4-hydroxyanilino) -1,3,5-triazine, 2- Octylmercapto-4,6-bis (3,5-di-tert-butyl-4-hydroxyanilino) -1,3,5-triazine, 2-octylmercapto-4,6-bis (3 , 5-di-tert-butyl-4-hydroxyphenoxy) -1,3,5-triazine, 2,4,6-tris (3,5-di-tert-butyl-4-hydroxyphenoxy ) -1,2,3-triazine, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris (4- tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, 2,4,6-tris (3,5-di-tert-butyl-4-hydroxyphenylethyl) -1,3 , 5-triazine, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hexahydro-1,3,5-triazine or 1,3,5- Tris (3,5-dicyclohexyl-4-hydroxybenzyl) isocyanurate;

Benzyl phosphonate, for example dimethyl-2,5-di-tert-butyl-4-hydroxybenzyl phosphonate, diethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate , Dioctadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzyl phosphonate or 3,5 Calcium salt of di-tert-butyl-4-hydroxybenzyl-phosphonic acid monoethyl ester;

Acylaminophenols such as 4-hydroxylauranilide, 4-hydroxystearanilide or octyl N- (3,5-di-tert-butyl-4-hydroxyphenyl) carbamate;

Monohydric or polyhydric alcohols such as methanol, ethanol, butanol, n-octanol, i-octanol (mixture of octanols), octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxyethyl) isocyanurate, N, N'-bis (hydroxyethyl) Oxamide, 3-thiaoundaneol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane or 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo [2.2.2] Esters of octane and β- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionic acid;

Monohydric or polyhydric alcohols such as methanol, ethanol, n-octanol, i-octanol (mixture of octanols), octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxyethyl) isocyanurate, N, N'-bis (hydroxyethyl) Oxamide, 3-thiaoundaneol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane or 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo- [2.2.2 ] Esters of octane and β- (5-tert-butyl-4-hydroxy-3-methylphenyl) -propionic acid;

Monohydric or polyhydric alcohols such as methanol, ethanol, octanol, i-octanol (a mixture of octanols), octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1, 2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxyethyl) isocyanurate, N, N'-bis (hydroxyethyl) oxamide , 3-thiaundaneol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane or 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo- [2.2.2] octane And esters of β- (3,5-dicyclohexyl-4-hydroxyphenyl) -propionic acid;

Monohydric or polyhydric alcohols such as methanol, ethanol, octanol, i-octanol (a mixture of octanols), octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1, 2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris (hydroxyethyl) isocyanurate, N, N'-bis (hydroxyethyl) oxamide , 3-thiaundaneol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane or 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo- [2.2.2] octane And esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid;

Amides of β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid, for example N, N'-bis (3,5-di-tert-butyl-4-hydroxyphenylpropionic acid) Hexamethylenediamide, N, N'-bis (3,5-di-tert-butyl-4-hydroxyphenylpyrropiionyl) trimethylenediamide, N, N'-bis (3,5-di-tert -Butyl-4-hydroxy-phenylpropionyl) hydrazide or N, N'-bis [2-3- [3,5-di-tert-butyl-4-hydroxyphenyl] propionyloxy) ethyl] Oxamide (Naugard ^R XL-1, supplied by Uniroyal).

For example, the antioxidant compound may be diphenylamine, a mixture of mono- and dialkylated tert-butyl / tert-octyl diphenylamine, a mixture of mono- and di-alkylated nonyldiphenylamine, phenylenediamine or N, N '-Di-sec-butyl-phenylenediamine.

The effective stabilization amount of component c) is from about 0.05 ppm / weight to about 10,000 ppm / weight based on the weight of the fuel composition. For example, component c) is present at about 0.1 ppm to about 1000 ppm, about 0.2 ppm to about 100 ppm, or about 0.5 ppm to about 25 ppm. For example, component c) is present at about 0.05 ppm to about 1000 ppm, about 0.05 ppm to about 100 ppm, or about 0.05 ppm to about 25 ppm, based on the weight of the total fuel blend. For example, component c) is present at about 0.1 ppm to about 10,000 ppm, about 0.2 ppm to about 10,000 ppm, or about 0.5 ppm to about 10,000 ppm based on the weight of the total fuel blend.

The stable ratio of nitroxide to antioxidant is, for example, about 1:99 to about 95: 5 (by weight). For example, the stable ratio of nitroxide to antioxidant may be about 1:10 to about 10: 1, about 1: 5 to about 5: 1, about 1: 3 to about 3: 1 or about 1: 1 (by weight) to be. A stable ratio of nitroxide to antioxidant is for example about 1: 4 (by weight).

The stabilized compositions of the present invention exhibit excellent filterability. Therefore, the present invention is a diesel fuel having a cetane number of 50 or less,

b) an effective amount of at least one compound selected from the group consisting of cetane enhancers; And

c) a stabilizing effective amount of at least one compound selected from the group consisting of i) stable nitroxide compounds, or

ii) a diesel fuel comprising adding a synergistic stabilizing effective amount of at least one compound selected from the group consisting of stable nitroxide compounds and at least one antioxidant compound selected from the group consisting of aromatic amine antioxidants and hindered phenolic antioxidants It provides a method of improving the filterability and cetane number of.

In addition, known additives may be present in the compositions and methods of the present invention. Additional additives include, for example, dispersants such as hydrocarbyl-substituted succinimides or succinamides and hydrocarbylpolyamines; Metal-based combustion enhancers such as ferrocene; Other antioxidants, such as corrosion inhibitors, amine formaldehyde products, antifoams, deodorants, antiwear agents, flow improvers, wax antistatic additives or other functional enhancers, cloud point inhibitors, abrasion modifiers, solubilizers, rust inhibitors, detergent lubricants, other thermal agents Stabilizers and the like. Other additives are present from about 5 ppm to about 500 ppm by weight of the total formulation.

The invention is illustrated by the following non-limiting examples. Unless stated otherwise, parts and percentages are by weight.

Diesel fuel filterability

Filterability was measured according to ASTM test method D6468. The diesel fuel sample was heated to 150 ° C. for 90 or 180 minutes under air. This fuel was filtered and the amount of deposit on the filter paper was measured by reflectance. The more deposits there are on the filter, the lower the reflectivity of the filter pad. Too much deposit will clog the filter in practical use.

The table below shows the results of using two different low sulfur diesel fuels. % Reflectance was measured on a sample heated to 150 ° C. for 90 minutes. The standard is ppm based on the fuel blend.

2-EHN: 2-ethylhexyl nitrate cetane enhancer;

Compound 1: bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate;

Compound 2: 1-oxyl-4-hydroxy-2,2,6,6-tetramethylpiperidine;

Compound 3: 1-oxyl-4-n-propoxy-2,2,6,6-tetramethylpiperidine;

Mixture 1: 14% compound 1, 56% mono- and dialkylated mixtures of tert-butyl / tert-octyl diphenylamine, 30% inert aromatic solvent (by weight).

Formulation A-D used diesel fuel 1. Formulation E-M used diesel fuel 2. The two fuels belong to the ASTM D975 specification (diesel fuel specification) in accordance with the present invention.

Cetane enhancers have been found to significantly reduce the filterability of diesel fuel. Even when 1 ppm of stable nitroxide compound is added, a significant decrease in precipitate appears, as can be seen by the filter pad reflectance measurement. Thus, when used in combination with nitroxide alone or in combination with other antioxidants, the tendency of diesel fuel to form insoluble materials that can clog fuel filters and fuel lines is reduced.

Claims (8)

a) diesel fuel having a cetane number of 50 or less; b) an effective amount of at least one compound selected from the group consisting of cetane enhancers; And c) at least one compound stabilizing effective amount selected from the group consisting of i) stable nitroxide compounds, or ii) a stabilized diesel fuel composition comprising at least one compound selected from the group consisting of stable nitroxide compounds and at least one antioxidant compound synergistically stabilizing effective amount selected from the group consisting of aromatic amine antioxidants and hindered phenolic antioxidants . 2. The cetane enhancer of claim 1 wherein the cetane enhancer is selected from the group consisting of hydrocarbyl nitrates, wherein the hydrocarbyl is a straight or branched chain alkyl having 1 to 24 carbon atoms, 2 comprising 1 to 3 oxygen atoms in between Straight or branched alkyl having from 24 to 24 carbon atoms, straight or branched alkenyl having from 3 to 24 carbon atoms, cycloalkyl having from 5 to 12 carbon atoms or C ₁ -C ₄ alkyl-substituted having from 5 to 12 carbon atoms A composition that is cycloalkyl. The method of claim 2, wherein the hydrocarbyl is methyl, ethyl, n-propyl, isopropyl, butyl, amyl, hexyl, heptyl, octyl, isooctyl, 2-ethylhexyl, nonyl, decyl, allyl, cyclopentyl, cyclohexyl , Methylcyclohexyl, cyclododecyl, 2-ethoxyethyl and 2- (2-ethoxyethoxy) ethyl. The composition of claim 2 wherein the hydrocarbyl nitrate is 2-ethylhexyl nitrate. The compound of claim 1, wherein the stable nitroxide compound is of formula Is a compound of or Formula Or a compound containing at least one group of Formula The composition is a compound of: In the food, Each R is, independently from each other, methyl or ethyl, T is a group necessary to complete a 5- or 6-membered ring, and E is a connector. The compound of claim 1, wherein the stable nitroxide compound is bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 4-hydroxy-1-oxyl-2, 2,6,6-tetramethylpiperidine, 4-ethoxy-1-oxyl-2,2,6,6-tetramethylpiperidine, 4-propoxy-1-oxy-2,2,6, 6-tetramethylpiperidine, 4-acetamido-1-oxyl-2,2,6,6-tetramethylpiperidine, 1-oxyl-2,2,6,6-tetramethylpiperidine, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-one, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-acetate, 1-oxyl- 2,2,6,6-tetramethylpiperidin-4-yl 2-ethylhexanoate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl stearate, 1- Oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butyl-benzo Eight, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) succinate, bis (1-oxyl-2,2,6,6-tetramethylpiperidine-4 Adipay , Bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butylmalonate, bis (1-oxyl-2,2,6,6-tetramethylpiperidine -4-yl) phthalate, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) isophthalate, bis (1-oxyl-2,2,6,6-tetramethyl Piperidin-4-yl) terephthalate, bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate, N, N'-bis (1-oxyl -2,2,6,6-tetramethylpiperidin-4-yl) adipamide, N- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) caprolactam , N- (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) dodecylsuccinimide, 2,4,6-tris- [N-butyl-N- (1- Oxyl-2,2,6,6-tetramethylpiperidin-4-yl)] s-triazine, 4,4'-ethylenebis (1-oxyl-2,2,6,6-tetramethylpiperazin 3-one), 2-oxyl-1,1,3,3-tetramethyl-2-isobenzazole, 1-oxyl-2,2,5,5-tetramethylpyrrolidone, N, N-bis (1,1,3,3-tetramethylbutyl) nitroxide, N, N-diphenyl A composition selected from the group consisting of nitroxyl, mono- and dialkylated tert-butyl / tert-octyl-N, N-diphenylnitroxyl and mixtures of mono- and dialkylated nonyl-N, N-diphenylnitroxyl . The method of claim 6, wherein the stable nitroxide is bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate or 4-hydroxy-1-oxyl-2,2 , 6,6-tetramethylpiperidine. In diesel fuel with a cetane number of 50 or less, b) an effective amount of at least one compound selected from the group consisting of cetane enhancers; And c) at least one compound stabilizing effective amount selected from the group consisting of i) stable nitroxide compounds, or ii) a diesel fuel comprising adding a synergistic stabilizing effective amount of at least one compound selected from the group consisting of stable nitroxide compounds and at least one antioxidant compound selected from the group consisting of aromatic amine antioxidants and hindered phenolic antioxidants How to improve the filterability and cetane number.