Patent ID: 8313542

Claim:
A composition comprising (a) a biodiesel fuel and (b) an antioxidizing effective amount of a mixture of (i) at least one aromatic diamine selected from N,N′-di-isopropyl-p-phenylenediamine; N,N′-di-sec-butyl-p-phenylenediamine; N,N′-bis(1,4-dimethylpentyl)-p-phenylenediamine; N,N′-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine; N,N′-bis(1-methylheptyl)-p-phenylenediamine; N,N′-dicyclohexyl-p-phenylenediamine; N,N′-dioctyl-p-phenylenediamine; (ii) at least one hindered phenol selected from 2,6-di-tert-butylphenol; 4-methyl-2,6-di-tert-butylphenol; 2,4,6-tri-tert-butylphenol; 2-tert-butylphenol; 2,6-diisopropylphenol; 2-methyl-6-tert-butylphenol; 2,4-dimethyl-6-tert-butylphenol; 4-ethyl-2,6-di-tert-butylphenol; 2-methyl-6-styrylphenol; 2,6-di-styryl-4-nonylphenol; 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-iso-butylphenol; 2,6-di-cyclopentyl-4-methylphenol; 2-(α-methylcyclohexyl)-4,6-dimethylphenol; 2,6-di-octadecyl-4-methylphenol; 2,4,6-tri-cyclohexylphenol; and (iii) at least one polyhydroxy phenol of general formula (III) wherein R is selected from the group consisting of H, alkyl, COOH and COOR 4 wherein R 4 is propyl, octyl or dodecyl; wherein the mixture of aromatic amine, hindered phenol and polyhydroxy phenol have a ratio of from about 1:4 to about 4:1 by weight of aromatic amine to hindered phenol plus polyhydroxy phenol.