Biodiesel and biodiesel blend fuels

Abstract

Fuel compositions are provided which comprise synergistic combinations of a biodiesel or biodiesel blend, an antioxidant comprising a mixture of at least one diphenol and at least one sterically hindered phenol, and a cetane improver. The fuel compositions described herein exhibit a unique combination of improved oxidation stability and enhanced ignition quality.

1 . A fuel composition comprising:
 (a) between about 0.01% to about 1% by volume of a cetane improver;   (b) a biodiesel blend comprising about 2% to about 98% by volume of a biodiesel and about 2% to about 98% by volume of a petroleum distillate; and   (c) an antioxidant comprising a mixture of a diphenol and a sterically hindered phenol, wherein
 (1) the amount of the antioxidant is (i) between about 20 milligrams per kilogram to about 10,000 milligrams per kilogram of the biodiesel blend, or (ii) is between about 16 milligrams per liter to about 8,000 milligrams per liter of the biodiesel blend, and 
 (2) wherein the volumetric ratio of the diphenol to the sterically hindered phenol is between about 0.01:1 to about 10:1. 
   
     
     
         2 . The fuel composition of  claim 1 , wherein:
 (a) the cetane improver is selected from the group consisting of 2-ethylhexyl nitrate, cyclohexyl nitrate, di-tert-butyl peroxide, 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, 2-ethylhexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate, n-octyl nitrate, sec-octyl nitrate, n-nonyl nitrate, n-decyl nitrate, n-dodecyl nitrate, cyclopentylnitrate, cyclohexylnitrate, methylcyclohexyl nitrate, isopropylcyclohexyl nitrate, 1-methoxypropyl-2-nitrate, 1-ethoxpropyl-2 nitrate, 1-isopropoxy-butyl nitrate, 1-ethoxylbutyl nitrate, and mixtures thereof;   (b) the biodiesel blend comprises (1) between about 2% to about 98% by volume of a biodiesel comprising between about 50% to about 99% by weight of methyl, ethyl, and propyl esters of saturated and unsaturated fatty acids, and (2) between about 2% to about 98% by volume of a petroleum distillate;   (c) the diphenol is selected from the group consisting of hydroquinone, tert-butylhydroquinone, 2-tert-butyl-1,4-hydroquinone, 2,5-di-tert-butyl-1,4-hydroquinone, methylhydroquinone, 2,5-di-tert.-octylhydroquinone, and mixtures thereof; and   (d) the sterically hindered phenol is selected from the group consisting of 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 2,4,6-tri-tert-butylphenol, 2,6-di-tert-butyl-4-dimethylaminomethylphenol, and mixtures thereof.   
     
     
         3 . The fuel composition of  claim 1 , wherein:
 (a) the cetane improver is selected from the group consisting of 2-ethylhexyl nitrate, cyclohexyl nitrate, di-tert-butyl peroxide, 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, 2-ethylhexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate, n-octyl nitrate, sec-octyl nitrate, n-nonyl nitrate, n-decyl nitrate, n-dodecyl nitrate, cyclopentylnitrate, cyclohexylnitrate, methylcyclohexyl nitrate, isopropylcyclohexyl nitrate, 1-methoxypropyl-2-nitrate, 1-ethoxpropyl-2 nitrate, 1-isopropoxy-butyl nitrate, 1-ethoxylbutyl nitrate and mixtures thereof;   (b) the biodiesel blend comprises (1) between about 2% to about 98% by volume of a biodiesel formed by transesterifying an alcohol with a composition selected from the group consisting of soybean oil, rapeseed oil, palm oil, canola oil, sunflower oil, olive oil, corn oil, coconut oil, jatropha oil, tallow oil, yellow grease animal fats, used cooking oil, and mixtures thereof, and (2) between about 2% to about 98% of a petroleum distillate;   (c) the diphenol is selected from the group consisting of hydroquinone, tert-butylhydroquinone, 2-tert-butyl-1,4-hydroquinone, 2,5-di-tert-butyl-1,4-hydroquinone, methylhydroquinone, 2,5-di-tert.-octylhydroquinone and mixtures thereof; and   (d) the sterically hindered phenol is selected from the group consisting of 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 2,4,6-tri-tert-butylphenol, 2,6-di-tert-butyl-4-dimethylaminomethylphenol, and mixtures thereof.   
     
     
         4 . The fuel composition of  claim 1 , wherein:
 (a) the cetane improver is selected from the group consisting of 2-ethylhexyl nitrate, cyclohexyl nitrate, di-tert-butyl peroxide, 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, 2-ethylhexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate, n-octyl nitrate, sec-octyl nitrate, n-nonyl nitrate, n-decyl nitrate, n-dodecyl nitrate, cyclopentylnitrate, cyclohexylnitrate, methylcyclohexyl nitrate, isopropylcyclohexyl nitrate, 1-methoxypropyl-2-nitrate, 1-ethoxpropyl-2 nitrate, 1-isopropoxy-butyl nitrate, 1-ethoxylbutyl nitrate and mixtures thereof;   (b) the biodiesel blend comprises (1) between about 2% to about 98% by volume of a biodiesel comprising a fatty acid ester selected from the group consisting of rapeseed methyl ester, a canola methyl ester, a soybean methyl ester, a corn oil methyl ester, or a mixture thereof, and (2) between about 2% to about 98% by volume of a diesel;   (c) the diphenol is selected from the group consisting of hydroquinone, tert-butylhydroquinone, 2-tert-butyl-1,4-hydroquinone, 2,5-di-tert-butyl-1,4-hydroquinone, methylhydroquinone, 2,5-di-tert.-octylhydroquinone, and mixtures thereof; and   (d) the sterically hindered phenol is selected from the group consisting of 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 2,4,6-tri-tert-butylphenol, 2,6-di-tert-butyl-4-dimethylaminomethylphenol, and mixtures thereof.   
     
     
         5 . The fuel composition of  claim 1 , wherein:
 (a) the cetane improver is selected from the group consisting of 2-ethylhexyl nitrate, cyclohexyl nitrate, di-tert-butyl peroxide, 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, 2-ethylhexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate, n-octyl nitrate, sec-octyl nitrate, n-nonyl nitrate, n-decyl nitrate, n-dodecyl nitrate, cyclopentylnitrate, cyclohexylnitrate, methylcyclohexyl nitrate, isopropylcyclohexyl nitrate, 1-methoxypropyl-2-nitrate, 1-ethoxpropyl-2 nitrate, 1-isopropoxy-butyl nitrate, 1-ethoxylbutyl nitrate and mixtures thereof;   (b) the biodiesel blend comprises (1) between about 2% to about 98% by volume of a biodiesel comprising a fatty acid ester selected from the group consisting of rapeseed methyl ester, a canola methyl ester, a soybean methyl ester, a corn oil methyl ester, or a mixture thereof, and (2) between about 2% to about 98% by volume of a diesel; and   (c) the diphenol and sterically hindered phenol are selected, respectively, from a compound of formula (I) and a compound of formula (II):   
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 3  are H or a tert-butyl group, and R 2  is H, CH 3 , a tert-butyl group or —CH 2 —N(CH 3 ) 2 . 
     
     
         6 . The fuel composition of  claim 1 , wherein:
 (a) the fuel composition contains about 0.1% to about 0.35% by volume of a cetane improver;   (b) the biodiesel blend comprises (1) about 5% to about 30% by volume of a biodiesel comprising a fatty acid ester selected from the group consisting of rapeseed methyl ester, a canola methyl ester, a soybean methyl ester, a corn oil methyl ester, or a mixture thereof, and (2) about 70 to about 90% by volume of a diesel;   (c) the diphenol is selected from the group consisting of tert-butylhydroquinone, 2-tert-butyl-1,4-hydroquinone, 2,5-di-tert-butyl-1,4-hydroquinone, methylhydroquinone, and 2,5-di-tert.-octylhydroquinone, and mixtures thereof;   (d) the sterically hindered phenol is selected from the group consisting of 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 2,4,6-tri-tert-butylphenol, and 2,6-di-tert-butyl-4-dimethylaminomethylphenol, and mixtures thereof;   (e) the fuel composition contains about 100 milligrams of antioxidant per liter of the biodiesel blend to about 500 milligrams of antioxidant per liter of the biodiesel blend; and   (f) the volumetric ratio of the diphenol to the sterically hindered phenol is between about 0.5:1 to about 1.5:1.   
     
     
         7 . The fuel composition of  claim 1 , wherein:
 (a) the fuel composition contains about 0.1% to about 0.35% by volume of a cetane improver;   (b) the biodiesel blend comprises (1) about 5% to about 30% by volume of a biodiesel comprising a fatty acid ester selected from the group consisting of rapeseed methyl ester, a canola methyl ester, a soybean methyl ester, a corn oil methyl ester, or a mixture thereof, and (2) about 70 to about 95% by volume of a diesel; and   (c) the diphenol is selected from the group consisting of tert-butylhydroquinone, 2-tert-butyl-1,4-hydroquinone, 2,5-di-tert-butyl-1,4-hydroquinone, methylhydroquinone, and 2,5-di-tert.-octylhydroquinone, and mixtures thereof;   (d) the sterically hindered phenol is selected from the group consisting of 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 2,4,6-tri-tert-butylphenol, and 2,6-di-tert-butyl-4-dimethylaminomethylphenol, and mixtures thereof;   (e) the fuel composition contains about 200 milligrams of antioxidant per liter of the biodiesel blend to about 400 milligrams of antioxidant per liter of the biodiesel blend; and   (f) the volumetric ratio of the diphenol to the sterically hindered phenol is between about 0.75:1 to about 1:1.   
     
     
         8 . The fuel composition of  claim 1 , wherein:
 (a) the fuel composition contains about 0.1% to about 0.35% by volume of a cetane improver;   (b) the biodiesel blend comprises (1) about 5% to about 15% by volume of a biodiesel comprising between about 50% to about 90% by weight of methyl, ethyl, and propyl esters of saturated and unsaturated fatty acids, and (2) about 85 to about 95% by volume of a diesel;   (c) the diphenol is selected from the group consisting of tert-butylhydroquinone, 2-tert-butyl-1,4-hydroquinone, 2,5-di-tert-butyl-1,4-hydroquinone, methylhydroquinone, and 2,5-di-tert.-octylhydroquinone, and mixtures thereof;   (d) the sterically hindered phenol is selected from the group consisting of 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 2,4,6-tri-tert-butylphenol, and 2,6-di-tert-butyl-4-dimethylaminomethylphenol, and mixtures thereof;   (e) the fuel composition contains about 200 milligrams of antioxidant per liter of the biodiesel blend to about 400 milligrams of antioxidant per liter of the biodiesel blend; and   
     
     
         9 . The fuel composition of  claim 1 , wherein the fuel composition further comprises a composition selected from the group consisting of an aromatic amine antioxidant and a performance additive. 
     
     
         10 . The fuel composition of  claim 1 , wherein the fuel composition comprises:
 (a) about 0.3% by volume of 2-ethylhexyl nitrate;   (b) a biodiesel blend comprising about 5% by volume of a biodiesel and about 95% by volume of a diesel; and   (c) about 400 milligrams per liter of the biodiesel blend of an antioxidant comprising a mixture of 2-tert-butyl-1,4-hydroquinone and a sterically hindered phenol, wherein the volumetric ratio of 2-tert-butyl-1,4-hydroquinone to the sterically hindered phenol is about 1:1.   
     
     
         11 . The fuel composition of  claim 1 , wherein the fuel composition comprises:
 (a) about 0.3% by volume of 2-ethylhexyl nitrate;   (b) a biodiesel blend comprising about 5% by volume of a biodiesel and about 95% by volume of a diesel; and   (c) about 400 milligrams per liter of the biodiesel blend of an antioxidant comprising a mixture of 2-tert-butyl-1,4-hydroquinone and a sterically hindered phenol selected from the group consisting of Ethanox® 4703 and Ethanox® 4733, wherein the volumetric ratio of 2-tert-butyl-1,4-hydroquinone to the sterically hindered phenol is about 1:1.   
     
     
         12 . The fuel composition of  claim 11 , wherein the biodiesel comprises soybean methyl ester. 
     
     
         13 . A fuel composition comprising:
 (a) between about 0.01% to about 1% by volume of a cetane improver;   (b) a biodiesel comprising between about 50% to about 99% by weight of methyl, ethyl, and propyl esters of saturated and unsaturated fatty acids; and   (c) an antioxidant comprising a mixture of a diphenol and a sterically hindered phenol, wherein
 (1) the amount of the antioxidant is (i) between about 20 milligrams per kilogram to about 10,000 milligrams per kilogram of the biodiesel, or (ii) is between about 16 milligrams per liter to about 8,000 milligrams per liter of the biodiesel, and 
 (2) wherein the volumetric ratio of the diphenol to the sterically hindered phenol is between about 0.01:1 to about 10:1. 
   
     
     
         14 . The fuel composition of  claim 13 , wherein:
 (a) the cetane improver is selected from the group consisting of 2-ethylhexyl nitrate, cyclohexyl nitrate, di-tert-butyl peroxide, 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, 2-ethylhexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate, n-octyl nitrate, sec-octyl nitrate, n-nonyl nitrate, n-decyl nitrate, n-dodecyl nitrate, cyclopentylnitrate, cyclohexylnitrate, methylcyclohexyl nitrate, isopropylcyclohexyl nitrate, 1-methoxypropyl-2-nitrate, 1-ethoxpropyl-2 nitrate, 1-isopropoxy-butyl nitrate, 1-ethoxylbutyl nitrate and mixtures thereof;   (b) the biodiesel is formed by transesterifying an alcohol with a composition selected from the group consisting of soybean oil, rapeseed oil, palm oil, canola oil, sunflower oil, olive oil, corn oil, tallow oil, coconut oil, jatropha oil, yellow grease animal fats, used cooking oil, and mixtures thereof;   (c) the diphenol is selected from the group consisting of hydroquinone, tert-butylhydroquinone, 2-tert-butyl-1,4-hydroquinone, 2,5-di-tert-butyl-1,4-hydroquinone, methylhydroquinone, 2,5-di-tert.-octylhydroquinone, and mixtures thereof; and   (d) the sterically hindered phenol is selected from the group consisting of 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 2,4,6-tri-tert-butylphenol, 2,6-di-tert-butyl-4-dimethylaminomethylphenol, and mixtures thereof.   
     
     
         15 . The fuel composition of  claim 13 , wherein:
 (a) the cetane improver is selected from the group consisting of 2-ethylhexyl nitrate, cyclohexyl nitrate, di-tent-butyl peroxide, 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, 2-ethylhexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate, n-octyl nitrate, sec-octyl nitrate, n-nonyl nitrate, n-decyl nitrate, n-dodecyl nitrate, cyclopentylnitrate, cyclohexylnitrate, methylcyclohexyl nitrate, isopropylcyclohexyl nitrate, 1-methoxypropyl-2-nitrate, 1-ethoxpropyl-2 nitrate, 1-isopropoxy-butyl nitrate, 1-ethoxylbutyl nitrate and mixtures thereof;   (b) the biodiesel comprises a fatty acid ester selected from the group consisting of rapeseed methyl ester, a canola methyl ester, a soybean methyl ester, a corn oil methyl ester, and mixtures thereof;   (c) the diphenol is selected from the group consisting of hydroquinone, tert-butylhydroquinone, 2-tert-butyl-1,4-hydroquinone, 2,5-di-tert-butyl-1,4-hydroquinone, methylhydroquinone, 2,5-di-tert.-octylhydroquinone, and mixtures thereof; and   (d) the sterically hindered phenol is selected from the group consisting of 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 2,4,6-tri-tert-butylphenol, 2,6-di-tert-butyl-4-dimethylaminomethylphenol, and mixtures thereof.   
     
     
         16 . the fuel composition of  claim 13 , wherein:
 (a) the cetane improver is selected from the group consisting of 2-ethylhexyl nitrate, cyclohexyl nitrate, di-tert-butyl peroxide, 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, 2-ethylhexyl nitrate, n-heptyl nitrate, sec-heptyl nitrate, n-octyl nitrate, sec-octyl nitrate, n-nonyl nitrate, n-decyl nitrate, n-dodecyl nitrate, cyclopentylnitrate, cyclohexylnitrate, methylcyclohexyl nitrate, isopropylcyclohexyl nitrate, 1-methoxypropyl-2-nitrate, 1-ethoxpropyl-2 nitrate, 1-isopropoxy-butyl nitrate, 1-ethoxylbutyl nitrate and mixtures thereof;   (b) the biodiesel comprises a fatty acid ester selected from the group consisting of rapeseed methyl ester, a canola methyl ester, a soybean methyl ester, a corn oil methyl ester, and mixtures thereof; and   (c) the diphenol and sterically hindered phenol are selected, respectively, from a compound of formula (I) and a compound of formula (II):   
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 3  are H or a tert-butyl group, and R 2  is H, CH 3 , a tert-butyl group or —CH 2 —N(CH 3 ) 2 . 
     
     
         17 . The fuel composition of  claim 13 , wherein:
 (a) the fuel composition contains about 0.1% to about 0.35% by volume of a cetane improver;   (b) the biodiesel comprises a fatty acid ester selected from the group consisting of rapeseed methyl ester, a canola methyl ester, a soybean methyl ester, a corn oil methyl ester, and mixtures thereof;   (c) the diphenol is selected from the group consisting of tert-butylhydroquinone, 2-tert-butyl-1,4-hydroquinone, 2,5-di-tert-butyl-1,4-hydroquinone, methylhydroquinone, and 2,5-di-tert.-octylhydroquinone, and mixtures thereof;   (d) the sterically hindered phenol is selected from the group consisting of 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 2,4,6-tri-tert-butylphenol, and 2,6-di-tert-butyl-4-dimethylaminomethylphenol, and mixtures thereof;   (e) the fuel composition contains about 100 milligrams of antioxidant per liter of the biodiesel to about 500 milligrams of antioxidant per liter of the biodiesel; and   (f) the volumetric ratio of the diphenol to the sterically hindered phenol is between about 0.5:1 to about 1.5:1.   
     
     
         18 . The fuel composition of  claim 13 , wherein:
 (a) the fuel composition contains about 0.1% to about 0.35% by volume of a cetane improver;   (b) the biodiesel comprises a fatty acid ester selected from the group consisting of rapeseed methyl ester, a canola methyl ester, a soybean methyl ester, a corn oil methyl ester, and mixtures thereof;   (c) the diphenol is selected from the group consisting of tert-butylhydroquinone, 2-tert-butyl-1,4-hydroquinone, 2,5-di-tert-butyl-1,4-hydroquinone, methylhydroquinone, and 2,5-di-tert.-octylhydroquinone, and mixtures thereof;   (d) the sterically hindered phenol is selected from the group consisting of 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 2,4,6-tri-tert-butylphenol, and 2,6-di-tert-butyl-4-dimethylaminomethylphenol, and mixtures thereof;   (e) the fuel composition contains about 400 milligrams of antioxidant per liter of the biodiesel; and   (f) the volumetric ratio of the diphenol to the sterically hindered phenol is between about 0.75:1 to about 1:1.   
     
     
         19 . The fuel composition of  claim 13 , wherein:
 (a) the fuel composition contains about 0.1% to about 0.35% by volume of a cetane improver;   (b) the biodiesel comprises about 50% to about 99% by weight of methyl, ethyl, and propyl esters of saturated and unsaturated fatty acids;   (c) the diphenol is selected from the group consisting of tert-butylhydroquinone, 2-tert-butyl-1,4-hydroquinone, 2,5-di-tert-butyl-1,4-hydroquinone, methylhydroquinone, and 2,5-di-tert.-octylhydroquinone, and mixtures thereof;   (d) the sterically hindered phenol is selected from the group consisting of 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-tert-butylphenol, 2,4,6-tri-tert-butylphenol, and 2,6-di-tert-butyl-4-dimethylaminomethylphenol, and mixtures thereof;   (e) the fuel composition contains about 400 milligrams of antioxidant per liter of the biodiesel; and   (f) the volumetric ratio of the diphenol to the sterically hindered phenol is between about 0.75:1 to about 1:1.   
     
     
         20 . The fuel composition of  claim 13 , wherein the fuel composition further comprises a composition selected from the group consisting of an aromatic amine antioxidant and a performance additive.