Use of additives with detergent action for further increasing the cetane number of fuel oils

Abstract

The present invention relates to the use of additives with detergent action selected from: (i) compounds with moieties derived from succinic anhydride and having hydroxyl and/or amino and/or amido and/or imido groups; (ii) nitrogen compounds quaternized in an acid-free manner, obtainable by addition of a compound comprising an oxygen- or nitrogen-containing group reactive with an anhydride and additionally a quaternizable amino group onto a polycarboxylic anhydride compound and subsequent quaternization; (iii) polytetrahydrobenzoxazines and bistetrahydrobenzoxazines for further increasing the cetane number of fuel oils which comprise cetane number improvers; furthermore, it relates to a fuel additive concentrate consisting of additives (i) to (iii), cetane number improvers, organic diluents or solvents and possibly customary co-additives.

1 . A method for increasing the cetane number of a fuel oil comprising a cetane number improver, the method comprising:
 adding at least one additive with detergent action to the fuel oil comprising a cetane number improver,   wherein the at least one additive is selected from the group consisting of:   (i) a compound with moieties derived from succinic anhydride and comprising at least one selected from the group consisting of a hydroxyl group, an amino group, an amido group, and an imido group;   (ii) a nitrogen compound quaternized in an acid-free manner, wherein the nitrogen compound is obtained by a process comprising:   adding a compound comprising an oxygen- or a nitrogen-comprising group reactive with an anhydride and additionally a quaternizable amino group into a polycarboxylic anhydride compound, and   subsequently quaternizing the compound, thereby obtaining the nitrogen compound;   (iii) polytetrahydrobenzoxazine and bistetrahydrobenzoxazine.   
     
     
         2 . The method of  claim 1 , wherein the fuel oil is free of mixtures of
 (A) aliphatic saturated or unsaturated monocarboxylic acids comprising 12 to 24 carbon atoms or dimerization or trimerization products thereof, which optionally are free carboxylic acids, ammonium salts, amides, esters or nitriles, and   (B) polycyclic hydrocarbon compounds, which are obtained by a process comprising: distilling residues of natural oils extracted from tree resins.   
     
     
         3 . The method of  claim 1 , wherein the at least one additive with detergent action is the nitrogen compound (ii). 
     
     
         4 . The method of  claim 3 , wherein the nitrogen compound is a polyisobutenylsuccinic monoamide obtained by a process comprising:
 reacting a polyisobutenylsuccinic anhydride comprising a polyisobutenyl radical having an M n  of from 500 to 2,500, with one or more N,N-di-(C 1 - to C 4 -alkyl)-amino-C 2 - to C 4 -alkyleneamines, and   subsequently quaternizing with an epoxide selected from the group consisting of ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide and styrene oxide, in the absence of a free acid at a temperature of from 50 to 100° C.   
     
     
         5 . The method of  claim 1 , wherein the cetane number improver is 2-ethylhexyl nitrate. 
     
     
         6 . The method of  claim 1 , wherein the fuel oil consists of
 (a) at least one biofuel oil based on fatty acid esters of from 0.1 to 100% by weight, and   (b) middle distillates of from 0 to 99.9% by weight, wherein the middle distillates are essentially hydrocarbon mixtures free of fatty acid esters and are selected from the group consisting of a middle distillate of fossil origin, a middle distillate of vegetable origin, and a middle distillate of animal origin.   
     
     
         7 . The method of  claim 1 , wherein the fuel oil has at least one property selected from the group consisting of:
 (α) a sulfur content of less than 50 mg/kg;   (β) a maximum content of 8% by weight of polycyclic aromatic hydrocarbons; and   (γ) a 95% distillation point in vol/vol at not more than 360° C.   
     
     
         8 . A fuel additive concentrate consisting of:
 (C1) 5 to 45% by weight of at least one additive with detergent action selected from the group consisting of:
 (i) a compound with moieties derived from succinic anhydride and comprising at least one selected from the group consisting of a hydroxy group, an amino group, an amide group, and an imido group; 
 (ii) a nitrogen compound quaternized in an acid-free manner, wherein the nitrogen compound is obtained by a process comprising: 
 adding a compound comprising an oxygen or a nitrogen-comprising group reactive with an anhydride and additionally a quaternizable amino group into a polycarboxylic anhydride compound, and 
 subsequently quaternizing the compound, 
 thereby obtaining the nitrogen compound; 
 (iii) polytetrahydrobenzoxazine and bistetrahydrobenzoxazine; 
   (C2) 20 to 90% by weight of at least one cetane number improver;   (C3) 5 to 35% by weight of at least one organic diluent or solvent selected from the group consisting of an aromatic hydrocarbon, an aliphatic hydrocarbon and an alcohol;   (C4) 0 to 10% by weight of one or more customary co-additives selected from the group consisting of:
 (iv) a corrosion inhibitor, wherein the corrosion inhibitor is not a mixture of (A) aliphatic saturated or unsaturated monocarboxylic acids comprising 12 to 24 carbon atoms or dimerization or trimerization products thereof, which optionally are free carboxylic acids, ammonium salts, amides, esters, or nitriles, and (B) polycyclic hydrocarbon compounds, which are obtained by a process comprising: distilling residues of natural oils extracted from tree resins; 
 (v) a demulifier; 
 (vi) a dehazer; 
 (vii) an antifoam; 
 (viii) an antioxidant and a stabilizer 
 (ix) a metal deactivator; 
 (x) an antistat; 
 (xi) a lubricity improver; and 
 (xii) a dye and a marker.