Fuels derived from animal or vegetable oil sources

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 —NR1R2 where R1 represents a group containing from 4 to 44 carbon atoms and R2 represents a hydrogen atom or a group R1 (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 - 16 . (canceled) 
     
     
         17 . A method of improving the filterability of a Bx fuel above the cloud point of the Bx fuel the method comprising adding to the fuel 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 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 group R 1  is a predominantly straight chain, substantially saturated hydrocarbyl group comprising from 10 to 24 carbon atoms; and the carboxylic acid is an optionally substituted benzene dicarboxylic acid. 
     
     
         18 . A method as claimed in claim  1 , in which the group R 2  is a group which conforms to the same definitions as are given for R 1 . 
     
     
         19 . A method as claimed in claim  2 , in which the compound (i) is a secondary amine of formula HNR 1 R 2  where R 1  and R 2  are as defined in claim  2 ; 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  2  and R 3  and R 4  independently represent a C(1-4) alkyl group. 
     
     
         20 . A method as claimed in claim  1 , in which the benzene dicarboxylic acids are selected from isophthalic acid, terephthalic acid and, especially, phthalic acid (and their acid anhydrides or acid halides). 
     
     
         21 . A method as claimed in claim  1 , in which the molar ratio of compound (i) to acid anhydride or acid halide (ii) is such that at least 50% of the acid groups (preferably at least 75%, preferably at least 90%, and most preferably 100%) are reacted in the reaction between the compounds (i) and (ii). 
     
     
         22 . A method as claimed in claim  1 , in which 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, preferably at least 1.5:1, preferably 2:1. 
     
     
         23 . A method as claimed in claim  1 , wherein the said additive is present in the Bx fuel in an amount of from 5 mg/kg fuel to 500 mg/kg fuel, preferably from 10 mg/kg fuel to 80 mg/kg fuel, preferably from 20 mg/kg fuel to 60 mg/kg fuel, preferably from 30 mg/kg fuel to 45 mg/kg fuel. 
     
     
         24 . A method as claimed in claim  1 , in which the Bx fuel is a blended fuel comprising a fuel component derived from an animal or, preferably, a vegetable oil source and a fuel component derived from a mineral source. 
     
     
         25 . A method as claimed in claim  8 , wherein the Bx fuel 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.