Improvements in fuels

Abstract

There is provided a method of providing an improved biofuel, by the presence of an additive which is the reaction product of (i) a compound containing the segment —NR 1 R 2 where R 1 represents a group containing from 4 to 44 carbon atom R 2 represents a hydrogen atom or a group R 1 (for example di-hydrogenated tallow amine) and (ii) a carboxylic acid having from 1 to 4 carboxylic acid groups or an acid anhydride or acid chloride thereof (for example phthalic acid or phthalic anhydride). The additives described combat problems arising from precipitation at temperatures above the cloud point.

1 . A method of treating a Bx fuel in order to improve the filterability of the Bx fuel above the cloud point of the Bx fuel, comprising adding to a Bx fuel a reaction product of (i) a compound containing the segment —NR 1 R 2  where R 1  represents a group containing from 4 to 44 carbon atoms and R 2  represents a hydrogen atom or a group R 1 , and (ii) a carboxylic acid having from 1 to 4 carboxylic acid groups or an acid anhydride or acid halide thereof;
 wherein the Bx fuel comprises fuel derived from animal or vegetable oil sources admixed with fuel derived from mineral or synthetic sources; 
 wherein the Bx fuel has a sulphur content less than 200 ppm; 
 wherein the Bx fuel contains at least 4 wt % of fuel derived from animal or vegetable sources; 
 and wherein the additive is present in the Bx fuel in an amount (as active material) of from 10 mg/kg up to 200 mg/kg. 
 
     
     
         2 . The method as claimed in  claim 1 , wherein the group R 1  is a predominantly straight chain, substantially saturated group comprising from 10 to 24 carbon atoms. 
     
     
         3 . The method as claimed in  claim 1 , wherein the group R 2  is a group R 1 . 
     
     
         4 . The method as claimed in  claim 3 , wherein the compound (i) is a secondary amine of formula HNR 1 R 2  where R 1  and R 2  are as defined in  claim 3 ; or is an ammonium salt having the cation +NR 1 R 2 R 3 R 4  where R 1  and R 2  are as defined in  claim 3  and R 3  and R 4  independently represent a C(1-4) alkyl group. 
     
     
         5 . The method as claimed in  claim 1 , wherein the carboxylic acid is an aminoalkylenepolycarboxylic acid selected from the group consisting of nitrilotriacetic acid, propylene diamine tetraacetic acid, ethylenediamine tetraacetic acid, dialkyl spirobislactones, and carboxylic acids based on cyclic skeletons having 5 to 13 carbon atoms in the cyclic moiety, wherein the carboxylic acids based on cyclic skeletons are selected from the group consisting of pyromellitic acid, cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, naphthalene dicarboxylic acid, 1,4-dicarboxylic acids and benzene dicarboxylic acids. 
     
     
         6 . The method as claimed in  claim 5 , wherein the carboxylic acid is an acid anhydride or an acide halide. 
     
     
         7 . The method as claimed in  claim 1 , wherein the molar ratio of compound (i) to acid anhydride or acid halide (ii) is such that at least 50% of the acid groups are reacted in the reaction between the compounds (i) and (ii). 
     
     
         8 . The method as claimed in  claim 1 , wherein compound (i) is a secondary amine and/or quaternary ammonium salt and compound (ii) is a dicarboxylic acid, or an acid anhydride or acid halide thereof, wherein the molar ratio of compound(s) (i) to acid, acid anhydride or acid halide (ii) is at least 1:1. 
     
     
         9 . The method as claimed in  claim 1 , wherein said additive is present in the Bx fuel in an amount of from 20 mg/kg fuel up to 80 mg/kg fuel. 
     
     
         10 . The method as claimed in  claim 1 , wherein the Bx fuel is a blended fuel comprising a fuel component derived from an animal or a vegetable oil source and a fuel component derived from a mineral source. 
     
     
         11 . The method as claimed in  claim 10 , wherein the Bx fuel further comprises one or more compounds which improve the flow properties of the fuel derived from the mineral source at a temperature below the cloud point of the Bx fuel. 
     
     
         12 - 14 . (canceled) 
     
     
         15 . A Bx fuel comprising a fuel additive which is the reaction product of (i) a compound containing the segment —NR 1 R 2  where R 1  represents a group containing from 4 to 44 carbon atoms and R 2  represents a hydrogen atom or a group R 1 , and (ii) an optionally substituted benzene dicarboxylic acid or an acid anhydride or acid halide thereof, wherein the Bx fuel has a sulphur content less than 200 ppm and contains at least 4 wt % of fuel derived from animal or vegetable sources; and wherein the additive is present in the Bx fuel in an amount as active material of from 10 mg/kg up to 200 mg/kg so as to provide improved filterability of the Bx fuel above the cloud point of the Bx fuel. 
     
     
         16 . (canceled) 
     
     
         17 . The method as claimed in  claim 5 , wherein the benzene dicarboxylic acid is selected from the group consisting of isophthalic acid, terephthalic acid and phthalic acid. 
     
     
         18 . The method as claimed in  claim 7 , wherein the benzene dicarboxylic acid is an acid anhydride or an acid halide.