Biodiesel fuel compositions having increased oxidative stability

Abstract

The present invention relates to biodiesel fuel compositions that have improved oxidation stability. More specifically, the biodiesel fuel compositions include at least one antioxidant that increases the oxidative stability of the fuel. The biodiesel fuel compositions may also include an antioxidant mixture, or an antioxidant mixture in combination with a polar and/or nonpolar solvent, that increases the oxidative stability of the fuel.

1 . A fuel composition, the composition comprising: 
 a. a biodiesel from a source other than rapeseed oil, frying oil, sunflower oil, and beef tallow; and    b. at least one antioxidant selected from the group consisting of 3,4,5-trihydroxybenzoic acid n-propyl ester, 1,2,3-trihydroxybenzene, butylated hydroxyanisole, 2,6-Di-tert-Butyl-1-Hydroxy-4-Methylbenzene, alpha-tocopherol acetate, alpha-tocopherol, gamma-tocopherol, delta-tocopherol, dilauryl thiodipropinate, isopropyl 2-hydroxy-4-methylthio butanoate, propyl gallate, dodecyl gallate, gallic acid, octyl gallate, ascorbyl palmitate, lecithin, stearyl citrate, palmityl citrate, chlorophyl, pyrogallol, alpha naphthol, ascorbic acid, natural tocopherol, citric acid, sage extract, rosemary, eugenol, natural antioxidant, and 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline.    
   
   
       2 . The fuel composition of  claim 1 , wherein the biodiesel is produced from soybean oil, the antioxidant is 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, and the fuel contains from about 50 ppm to about 500 ppm 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline.  
   
   
       3 . The fuel composition of  claim 1 , further comprising an additive selected from the group comprising of cetane improvers, ignition accelerators, metal deactivators, corrosion inhibitors, thermal stabilizers, detergents, antiwear agents, and demulsifiers.  
   
   
       4 . A fuel composition, the composition comprising: 
 a. a biodiesel; and    b. an antioxidant mixture, the mixture comprising at least two antioxidant selected from the group consisting of 2-tert-butylhydroquinone, 3,4,5-trihydroxybenzoic acid n-propyl ester, 1,2,3-trihydroxybenzene, butylated hydroxyanisole, 2,6-Di-tert-Butyl-1-Hydroxy-4-Methylbenzene, alpha-tocopherol acetate, alpha-tocopherol, gamma-tocopherol, delta-tocopherol, dilauryl thiodipropinate, isopropyl 2-hydroxy-4-methylthio butanoate, propyl gallate, dodecyl gallate, gallic acid, octyl gallate, ascorbyl palmitate, lecithin, stearyl citrate, palmityl citrate, chlorophyl, pyrogallol, alpha naphthol, ascorbic acid, natural tocopherol, citric acid, sage extract, rosemary, eugenol, natural antioxidant, and 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline.    
   
   
       5 . The fuel composition of  claim 4 , wherein the biodiesel is produced from a source selected from the group consisting of soybean oil, yellow grease, corn oil, rapeseed oil, coconut oil, peanut oil, palm oil, fish oil, marine oil, cottonseed oil, mustard seed oil, camelina oil, jojoba oil, hemp oil, tallow, poultry fat, lard, safflower oil, jatropha oil, algae oil, and sunflower oil.  
   
   
       6 . The fuel composition of  claim 4 , wherein the biodiesel is produced from rapeseed oil.  
   
   
       7 . The fuel composition of  claim 4 , wherein the biodiesel is produced from algae oil.  
   
   
       8 . The fuel composition of  claim 4 , wherein the biodiesel is produced from soybean oil.  
   
   
       9 . The fuel composition of  claim 8 , wherein the antioxidant mixture comprises 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline and 2-tert-butylhydroquinone.  
   
   
       10 . The fuel composition of  claim 8 , wherein the antioxidant mixture comprises butylated hydroxyanisole, 2,6-Di-tert-Butyl-1-Hydroxy-4-Methylbenzene, 6-ethoxy-6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, 2-tert-butylhydroquinone.  
   
   
       11 . The fuel composition of  claim 10 , wherein the antioxidant mixture comprises from about 20 ppm to about 500 ppm of a mixture of Butylated Hydroxyanisole and 2,6-Di-tert-Butyl-1-Hydroxy-4-Methylbenzene, from about 20 ppm to about 500 ppm of 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, and from about 10 to about 60 ppm of 2-tert-butylhydroquinone.  
   
   
       12 . The fuel composition of  claim 8 , further comprising a nonpolar solvent.  
   
   
       13 . The fuel composition of  claim 12 , wherein the antioxidant mixture comprises butylated hydroxyanisole, and 2,6-Di-tert-Butyl-1-Hydroxy-4-Methylbenzene and the nonpolar solvent is a vegetable oil.  
   
   
       14 . The fuel composition of  claim 4 , further comprising a polar solvent.  
   
   
       15 . The fuel composition of  claim 4 , the composition further comprising a petroleum based diesel fuel.  
   
   
       16 . The fuel composition of  claim 15 , the composition comprising from about 20% to about 30% by weight of the fuel composition of  claim 4  and from about 70% to about 80% by weight petroleum based diesel fuel.  
   
   
       17 . The fuel composition of  claim 4 , further comprising an additive selected from the group comprising of cetane improvers, ignition accelerators, metal deactivators, corrosion inhibitors, thermal stabilizers, detergents, antiwear agents, and demulsifiers.  
   
   
       18 . A fuel composition, the composition comprising: 
 a. a biodiesel;    b. a first antioxidant having Formula (I);                        wherein: 
 R 1 , R 2 , R 3  and R 4  are independently selected from the group consisting of hydrogen and an alkyl group having from 1 to about 6 carbons; and  
 R 5  is an alkoxy group having from 1 to about 12 carbons;  
     c. a second antioxidant not having Formula (I);    d. a polar solvent; and,    e. a nonpolar solvent, wherein the two solvents form a homogeneous liquid.    
   
   
       19 . The fuel composition of  claim 18 , wherein the second antioxidant is selected from the group consisting of 2-tert-butylhydroquinone, 3,4,5-trihydroxybenzoic acid n-propyl ester, 1,2,3-trihydroxybenzene, butylated hydroxyanisole, 2,6-Di-tert-Butyl-1-Hydroxy-4-Methylbenzene, alpha-tocopherol acetate, alpha-tocopherol, gamma-tocopherol, delta-tocopherol, dilauryl thiodipropinate, isopropyl 2-hydroxy-4-methylthio butanoate, propyl gallate, dodecyl gallate, gallic acid, octyl gallate, ascorbyl palmitate, lecithin, stearyl citrate, palmityl citrate, chlorophyl, pyrogallol, alpha naphthol, ascorbic acid, natural tocopherol, citric acid, sage extract, rosemary, eugenol, natural antioxidant, and combinations thereof.  
   
   
       20 . The fuel composition of  claim 18 , wherein the polar solvent is selected from the group consisting of glycerol, propylene glycol, propylene glycol, polyol, a sugar alcohol, and combinations thereof.  
   
   
       21 . The fuel composition of  claim 18 , wherein the nonpolar solvent is selected from the group consisting of vegetable oil, monoglycerides, diglycerides, triglycerides, and combinations thereof.  
   
   
       22 . The fuel composition of  claim 18 , wherein the biodiesel is produced from a source selected from the group consisting of soybean oil, yellow grease, corn oil, rapeseed oil, coconut oil, peanut oil, palm oil, fish oil, marine oil, cottonseed oil, mustard seed oil, camelina oil, jojoba oil, hemp oil, tallow, poultry fat, lard, safflower oil, jatropha oil, algae oil, and sunflower oil.  
   
   
       23 . The fuel composition of  claim 18 , wherein the biodiesel is produced from rapeseed oil.  
   
   
       24 . The fuel composition of  claim 18 , wherein the biodiesel is produced from algae oil.  
   
   
       25 . The fuel composition of  claim 18 , wherein the biodiesel is produced from soybean oil.  
   
   
       26 . The fuel composition of  claim 25 , wherein the first antioxidant is 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, the second antioxidant is a natural antioxidant.  
   
   
       27 . The fuel composition of  claim 25 , wherein the first antioxidant is 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, the second antioxidant is a mixture of propyl gallate, dilauryl thiodipropionate, ascorbyl palmitate, and butylated hydroxyanisole, and the polar solvent is propylene glycol.  
   
   
       28 . The fuel composition of  claim 25 , wherein the first antioxidant is 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, the second antioxidant is a mixture of dodecyl gallate, alpha naphthol, natural tocopherol, and ascorbyl palmitate, and the polar solvent is propylene glycol.  
   
   
       29 . The fuel composition of  claim 25 , wherein the first antioxidant is 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, the second antioxidant is a mixture of 2-6-di-tert-butyl-4-methylphenol, pyrogallol, 2-tert-butylhydroquinone, and stearyl citrate, and the nonpolar solvent is corn oil.  
   
   
       30 . The fuel composition of  claim 25 , wherein the first antioxidant is 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, the second antioxidant is a mixture of natural mixed tocopherols, ascorbyl palmitate, propyl gallate, 2-tert-butylhydroquinone, and lecithin, and the nonpolar solvent is corn oil.  
   
   
       31 . The fuel composition of  claim 25 , wherein the first antioxidant is 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, the second antioxidant is citric acid, and the nonpolar solvent is corn oil.  
   
   
       32 . The fuel composition of  claim 31 , wherein the second antioxidant further comprises 2-tert-butylhydroquinone and 1,2-Propanediol.  
   
   
       33 . The fuel composition of  claim 25 , wherein the first antioxidant is 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, the second antioxidant is 2-tert-butylhydroquinone, and the second nonpolar solvent is corn oil.  
   
   
       34 . The fuel composition of  claim 18 , further comprising an additive selected from the group comprising of cetane improvers, ignition accelerators, metal deactivators, corrosion inhibitors, thermal stabilizers, detergents, antiwear agents, and demulsifiers.  
   
   
       35 . A method of increasing the oxidative stability of a fuel composition, the method comprising contacting a biodiesel with an antioxidant mixture comprising at least two antioxidants selected from the group consisting of 2-tert-butylhydroquinone, 3,4,5-trihydroxybenzoic acid n-propyl ester, 1,2,3-trihydroxybenzene, butylated hydroxyanisole, 2,6-Di-tert-Butyl-1-Hydroxy-4-Methylbenzene, alpha-tocopherol acetate, alpha-tocopherol, gamma-tocopherol, delta-tocopherol, dilauryl thiodipropinate, isopropyl 2-hydroxy-4-methylthio butanoate, propyl gallate, dodecyl gallate, gallic acid, octyl gallate, ascorbyl palmitate, lecithin, stearyl citrate, palmityl citrate, chlorophyl, pyrogallol, alpha naphthol, ascorbic acid, natural tocopherol, citric acid, sage extract, rosemary, eugenol, natural antioxidant, and 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline.  
   
   
       36 . The method of  claim 35 , wherein the biodiesel is produced from a source selected from the group consisting of soybean oil, yellow grease, corn oil, rapeseed oil, coconut oil, peanut oil, palm oil, fish oil, marine oil, cottonseed oil, mustard seed oil, camelina oil, jojoba oil, hemp oil, tallow, poultry fat, lard, safflower oil, jatropha oil, algae oil, and sunflower oil.  
   
   
       37 . The method of  claim 35 , wherein the biodiesel is produced from rapeseed oil.  
   
   
       38 . The method of  claim 35 , wherein the biodiesel is produced from algae oil.  
   
   
       39 . The method of  claim 35 , wherein the biodiesel is produced from soybean oil.  
   
   
       40 . The method of  claim 39 , further comprising a polar solvent.  
   
   
       41 . The method of  claim 40 , wherein the antioxidant mixture comprises 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, propyl gallate, dilauryl thiodipropionate, ascorbyl palmitate, and butylated hydroxyanisole, and the polar solvent is propylene glycol.  
   
   
       42 . The method of  claim 40 , wherein the antioxidant mixture comprises 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, dodecyl gallate, alpha naphthol, natural tocopherol, and ascorbyl palmitate, and the polar solvent is propylene glycol.  
   
   
       43 . The method of  claim 39 , further comprising a nonpolar solvent.  
   
   
       44 . The method of  claim 43 , wherein the antioxidant mixture comprises 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, 2-6-di-tert-butyl-4-methylphenol, pyrogallol, 2-tert-butylhydroquinone, and stearyl citrate, and the nonpolar solvent is corn oil.  
   
   
       45 . The method of  claim 43 , wherein the antioxidant mixture comprises 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, natural mixed tocopherols, ascorbyl palmitate, propyl gallate, 2-tert-butylhydroquinone, and lecithin, and the nonpolar solvent is corn oil.  
   
   
       46 . The method of  claim 43 , wherein the antioxidant mixture comprises 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline and citric acid, and the nonpolar solvent is corn oil.  
   
   
       47 . The method of  claim 46 , wherein the antioxidant mixture further comprises 2-tert-butylhydroquinone and 1,2-Propanediol.  
   
   
       48 . The method of  claim 43 , wherein the antioxidant mixture comprises 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, 2-tert-butylhydroquinone, and the nonpolar solvent is corn oil.  
   
   
       49 . The method of  claim 35 , further comprising contacting an additive with the biodiesel and the antioxidant mixture.  
   
   
       50 . The method of  claim 49 , wherein the additive is selected from the group comprising of cetane improvers, ignition accelerators, metal deactivators, corrosion inhibitors, thermal stabilizers, detergents, antiwear agents, and demulsifiers.  
   
   
       51 . The method of  claim 35 , wherein the antioxidant mixture comprises 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline and a second antioxidant and the fuel composition has less than 2.8 mg/100 ml of filterable insolubles.  
   
   
       52 . The method of  claim 35 , wherein the antioxidant mixture comprises 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline and a second antioxidant and the fuel composition has less than 4.3 mg/100 ml of adherent insolubles.  
   
   
       53 . The method of  claim 35 , wherein the antioxidant mixture comprises 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline and a second antioxidant and the fuel composition has less than 6.8 mg/100 ml of total insolubles.  
   
   
       54 . The method of  claim 35 , wherein the fuel has a kinematic viscosity at 40° C. of from about 4.00 mm 2 /sec to about 5.0 mm 2 /sec.  
   
   
       55 . The method of  claim 35 , wherein the fuel has an acid value of from about 0.1 mg KOH/g to about 0.75 mg KOH/g.  
   
   
       56 . The method of  claim 35 , wherein the fuel has a density at 20° C. of from about 0.865 g/cm 3  to about 0.884 g/cm 3 .  
   
   
       57 . The method of  claim 35 , wherein the fuel has a cold filter plugging point (CFPP) of from about −1° C. to about −10° C.  
   
   
       58 . The method of  claim 35 , wherein the fuel has a sulphated ash percent by mass of from about 0.001% by mass to about 0.002% by mass.