Fuel compositions having improved cloud point and improved storage properties

Abstract

The present invention relates to a fuel composition comprising at least one biodiesel fuel and comprising 0.05 to 5% by weight of at least one polymer comprising ester groups, which comprises repeat units derived from ester monomers having 16 to 40 carbon atoms in the alcohol radical, and repeat units derived from ester monomers having 7 to 15 carbon atoms in the alcohol radical, and the polymer comprising ester groups has a weight-average molecular weight in the range from 5000 to 100 000 g/mol. The present invention further describes the use of polymers comprising ester groups as flow improvers in fuel compositions which comprise at least one biodiesel fuel. Surprising advantages can be achieved especially with regard to the improvement of the cloud point and the low-temperature storability.

1 . A fuel composition comprising at least one biodiesel fuel, wherein the fuel composition further comprises 0.05 to 5% by weight of at least one polymer comprising ester groups, which comprises repeat units derived from ester monomers having 16 to 40 carbon atoms in the alcohol radical, and repeat units derived from ester monomers having 7 to 15 carbon atoms in the alcohol radical, and the polymer comprising ester groups has a weight-average molecular weight in the range from 5000 to 100 000 g/mol. 
     
     
         2 . The fuel composition according to  claim 1 , wherein the fuel composition comprises at least 80% by weight of biodiesel fuel. 
     
     
         3 . The fuel composition according to  claim 1 , wherein the polymer comprising ester groups is selected from the group consisting of a polyalkyl (meth)acrylate (PAMA), a polyalkyl fumarate and a polyalkyl maleate. 
     
     
         4 . The fuel composition according to  claim 2 , wherein the polymer comprising ester groups comprises 40 to 70% by weight of units derived from ester monomers having 16 to 40 carbon atoms in the alcohol radical. 
     
     
         5 . The fuel composition according to  claim 2 , wherein the polymer comprising ester groups comprises 30 to 60% by weight of units derived from ester monomers having 7 to 15 carbon atoms in the alcohol radical. 
     
     
         6 . The fuel composition according to t  claim 2 , wherein the polymer comprising ester groups is obtainable by polymerizing a monomer mixture which comprises 0 to 40% by weight of one or more ethylenically unsaturated ester compounds of the formula (I) 
       
         
           
           
               
               
           
         
       
       in which R is hydrogen or methyl, R 1  is a linear or branched alkyl radical having 1 to 6 carbon atoms, R 2  and R 3  are each independently hydrogen or a group of the formula —COOR′ in which R′ is hydrogen or an alkyl group having 1 to 6 carbon atoms,
 10 to 98% by weight of one or more ethylenically unsaturated ester compounds of the formula (II) 
 
       
         
           
           
               
               
           
         
       
       in which R is hydrogen or methyl, R 4  is a linear or branched alkyl radical having 7 to 15 carbon atoms, R 5  and R 6  are each independently hydrogen or a group of the formula —COOR″ in which R″ is hydrogen or an alkyl group having 7 to 15 carbon atoms, and 0.1 to 80% by weight of one or more ethylenically unsaturated ester compounds of the formula (III) 
       
         
           
           
               
               
           
         
       
       in which R is hydrogen or methyl, R 7  is a linear or branched alkyl radical having 16 to 40 carbon atoms, R 8  and R 9  are each independently hydrogen or a group of the formula —COOR′″ in which R′″ is hydrogen or an alkyl group having 16 to 40 carbon atoms. 
     
     
         7 . The fuel composition according to  claim 6 , wherein the weight ratio of repeat units derived from ester monomers having 7 to 15 carbon atoms in the alcohol radical to repeat units derived from ester monomers having 16 to 40 carbon atoms in the alcohol radical is in the range from 1:1 to 1:3. 
     
     
         8 . The fuel composition according to  claim 2 , wherein the biodiesel fuel comprises fatty acid esters derived from monohydric alcohols having 1 to 4 carbon atoms. 
     
     
         9 . The fuel composition according to  claim 8 , wherein the monoester is a methyl ester. 
     
     
         10 . The fuel composition according to  claim 9 , wherein the fuel comprises at least 6% by weight of palmitic acid methyl ester and/or stearic acid methyl ester. 
     
     
         11 . The fuel composition according to  claim 2 , wherein the biodiesel fuel comprises at least 35% by weight of saturated fatty acid esters which have at least 16 carbon atoms in the fatty acid radical. 
     
     
         12 . The fuel composition according to  claim 2 , wherein the biodiesel fuel is derived from palm oil, soya oil, jatropha oil or animal tallow. 
     
     
         13 . The fuel composition according to  claim 2 , wherein the fuel composition comprises at least one additive. 
     
     
         14 . The fuel composition according to  claim 12 , wherein at least one additive is selected from the group consisting of a dispersant, a demulsifier, a defoamer, a lubricity additive, an antioxidant, a cetane number improver, a detergent, a dye, a corrosion inhibitor and an odorant. 
     
     
         15 . The fuel composition according to  claim 2 , wherein the fuel composition comprises 0.1 to 1% by weight of at least one polymer comprising ester groups. 
     
     
         16 . The fuel composition according to  claim 2 , wherein the fuel composition comprises at most 0.05% by weight of ethylene copolymer. 
     
     
         17 . (canceled) 
     
     
         18 . The fuel composition which comprises at least one biodiesel fuel according to  claim 1  wherein the cloud point of the fuel composition decreases from a value less than or equal to 12° C. by at least 1° C. 
     
     
         19 . (canceled) 
     
     
         20 . The fuel composition which comprises at least one biodiesel fuel according to  claim 1  wherein the fuel composition may be stored at temperatures below the cloud point without significant separation of the fuel or formation of precipitate. 
     
     
         21 . The fuel composition according to  claim 12 , wherein the animal tallow is selected from a group consisting of beef fat, chicken fat, and pork fat. 
     
     
         22 . The fuel composition according to  claim 1 , wherein the fuel composition has a pour point having a value less than or equal to 12° C.