Fuel Oil Compositions

Abstract

A method of improving the low temperature properties of a fuel oil and minor amounts of (a) at least one polar nitrogen compound effective and (b) at least one polyamine detergent is disclosed. The method involves adding to the composition (c) at least one acidic organic species.

1 . A method of improving the low temperature properties of a fuel oil composition comprising a major amount of a fuel oil and minor amounts of (a) at least one polar nitrogen compound effective as a wax anti-settling additive and (b) at least one polyamine detergent comprising adding at least one acidic organic species to the fuel oil. 
     
     
         2 . A method according to  claim 1  wherein, the at least one polar nitrogen compound comprises an oil-soluble polar nitrogen compound carrying one or more substituents of the formula >NR 13 , where R 13  represents a hydrocarbyl group containing 8 to 40 atoms, which substituent or one or more of which substituents may be in the form of a cation derived therefrom. 
     
     
         3 . A method according to  claim 1  wherein, the at least one polar nitrogen compound comprises an amide-amine salt formed by reacting 1 molar portion of phthalic anhydride with 2 molar portions of dihydrogenated tallow amine. 
     
     
         4 . A method according to  claim 1  wherein, the at least one polyamine detergent comprises the reaction product between a poly(isobutene) substituted succinic anhydride acylating agent with a polyamine or mixture of polyamines. 
     
     
         5 . A method according to  claim 4  wherein the poly(isobutene) has a number average molecular weight (Mn) ranging from 400-2500. 
     
     
         6 . A method according to  claim 1  wherein the acidic organic species comprises an unsaturated, monocarboxylic acid having between 8 and 30 carbon atoms. 
     
     
         7 . A method according to  claim 1  wherein the low temperature properties improved are ΔCP, CFPP or both. 
     
     
         8 . A method for improving the low temperature properties of a fuel oil composition comprising adding at least one acidic organic species to a fuel oil composition; wherein the fuel oil composition comprises a major amount of a fuel oil and minor amounts of (a) at least one polar nitrogen compound effective as a wax anti-settling additive and (b) at least one polyamine detergent. 
     
     
         9 . A method for restoring a loss in low temperature properties of a fuel oil comprising adding at least one acidic organic species comprising at least one polar nitrogen compound to a fuel oil. 
     
     
         10 . A process of ameliorating a negative interaction on the low temperature performance of (a) a polar nitrogen compound effective as a wax anti-settling additive attributable to its use in combination with (b) at least one polyamine detergent, the process comprising:
 (i) determining for a fuel oil composition comprising a major amount of a fuel oil and minor amounts of (a) and (b), the amounts of (a) and (b) such that the low temperature properties of the fuel oil composition are inferior to the low temperature properties of a fuel oil composition comprising the same amount of (a) in the absence of (b); and,   (ii) determining an amount of (c) at least one acidic organic species, which when added to the fuel oil composition is such that the low temperature properties of the fuel oil composition are improved; and,   (iii) manufacturing a fuel oil composition comprising (a), (b) and (c) in the amounts determined in (i) and (ii).