Oxidation inhibitor for diesel, and diesel fuel composition

Abstract

The present invention provides an oxidation inhibitor for diesel that improves the oxidative stability thereof and a diesel fuel composition having an excellent oxidative stability. A diesel fuel composition excellent in oxidative stability and low-temperature fluidity is obtained by adding an oxidation inhibitor that contains a fatty acid methyl ester derived from palm, rapeseed or soybean oil and in which the contents of polyunsaturated and saturated fatty acid methyl esters are each specified.

1 . A method of inhibiting oxidation of diesel comprising adding to diesel an oxidation inhibitor for diesel which comprises a palm oil-derived fatty acid methyl ester, wherein said oxidation inhibitor contains 0.5 mass %-7.0 mass % of polyunsaturated fatty acid methyl ester and 50 mass %-84 mass % of saturated fatty acid methyl ester. 
     
     
         2 . A method of inhibiting oxidation of diesel comprising adding to diesel an oxidation inhibitor for diesel which comprises a rapeseed oil-derived fatty acid methyl ester, wherein said oxidation inhibitor contains 0.5 mass %-24.5 mass % of polyunsaturated fatty acid methyl ester and 7 mass %-50 mass % of saturated fatty acid methyl ester. 
     
     
         3 . A method of inhibiting oxidation of diesel comprising adding to diesel an oxidation inhibitor for diesel which comprises a soybean oil-derived fatty acid methyl ester, wherein said oxidation inhibitor contains 0.8 mass %-32 mass % of polyunsaturated fatty acid methyl ester and 15 mass %-56 mass % of saturated fatty acid methyl ester. 
     
     
         4 . A diesel fuel composition, which comprises an oxidation inhibitor for diesel comprising at least one selected from the group consisting of a palm oil-derived fatty acid methyl ester, a rapeseed oil-derived fatty acid methyl ester, and a soybean oil-derived fatty acid methyl ester, in an amount of 1.0 mass % or more and 70 mass % or less,
 wherein said palm oil-derived fatty acid methyl ester contains 0.5 mass %-7.0 mass % of polyunsaturated fatty acid methyl ester and 50 mass %-84 mass % of saturated fatty acid methyl ester,   wherein said rapeseed oil-derived fatty acid methyl ester contains 0.5 mass %-24.5 mass % of polyunsaturated fatty acid methyl ester and 7 mass %-50 mass % of saturated fatty acid methyl ester, and   wherein said soybean oil-derived fatty acid methyl ester contains 0.8 mass %-32 mass % of polyunsaturated fatty acid methyl ester and 15 mass %-56 mass % of saturated fatty acid methyl ester.   
     
     
         5 . The diesel fuel composition of  claim 4 , which comprises an oxidation inhibitor for diesel comprising at least one selected from the group consisting of the palm oil-derived fatty acid methyl ester, the rapeseed oil-derived fatty acid methyl ester, and the soybean oil-derived fatty acid methyl ester, in an amount of 1.0 mass % or more and 20 mass % or less. 
     
     
         6 . The diesel fuel composition of  claim 4 , which comprises an oxidation inhibitor for diesel comprising at least one selected from the group consisting of the palm oil-derived fatty acid methyl ester, the rapeseed oil-derived fatty acid methyl ester, and the soybean oil-derived fatty acid methyl ester, in an amount of more than 20 mass % and 50 mass % or less. 
     
     
         7 . The diesel fuel composition of  claim 4 , which comprises an oxidation inhibitor for diesel comprising at least one selected from the group consisting of the palm oil-derived fatty acid methyl ester, the rapeseed oil-derived fatty acid methyl ester, and the soybean oil-derived fatty acid methyl ester, in an amount of more than 50 mass % and 70 mass % or less. 
     
     
         8 . The diesel fuel composition of  claim 4 , which satisfies all the following conditions (a), (b), and (c):
 (a) the pour point is 9° C. or less;   (b) the oxidative stability by PetroOxy method is 65 minutes or more; and,   (c) no sludge is formed after forced-oxidation test performed by supplying pure oxygen at 115° C. for 16 hours.   
     
     
         9 . The diesel fuel composition of  claim 5 , which satisfies all the following conditions (a-1), (b), and (c):
 (a-1) a pour point is −8° C. or less;   (b) an oxidative stability by PetroOxy method is 65 minutes or more; and,   (c) no sludge is formed after forced-oxidation test performed by supplying pure oxygen at 115° C. for 16 hours.   
     
     
         10 . The diesel fuel composition of  claim 6 , which satisfies all the following conditions (a-2), (b), and (c):
 (a-2) a pour point is 4° C. or less;   (b) an oxidative stability by PetroOxy method is 65 minutes or more; and,   (c) no sludge is formed after forced-oxidation test performed by supplying pure oxygen at 115° C. for 16 hours.   
     
     
         11 . The diesel fuel composition of  claim 7 , which satisfies all the following conditions (a), (b), and (c):
 (a) a pour point is 9° C. or less;   (b) an oxidative stability by PetroOxy method is 65 minutes or more; and,   (c) no sludge is formed after forced-oxidation test performed by supplying pure oxygen at 115° C. for 16 hours.