Distillate fuel compositions for improved combustion and engine cleanliness

Abstract

The invention provides a distillate fuel additive composition, and also a fuel composition containing a distillate fuel, an overbased calcium sulfonate detergent, a succinimide dispersant, and an organomanganese compound. Also provided is a method for improving the cleanliness of diesel fuel intake systems by the combustion in said systems of a distillate fuel containing the fuel additive composition.

1 . A distillate fuel additive composition comprising an organometallic manganese compound, an alkyl-substituted succinimide ashless dispersant, and an overbased calcium sulfonate detergent.  
     
     
         2 . The fuel additive of  claim 1  wherein the organometallic manganese compound comprises methylcyclopentadienylmanganese tricarbonyl.  
     
     
         3 . The fuel additive of  claim 1  wherein the succinimide is prepared from polyisobutylene succinic anhydride and a polyalkylene polyamine.  
     
     
         4 . The fuel additive of  claim 1  wherein the succinimide is prepared from polyisobutylene succinic anhydride and tetraethylenepentamine.  
     
     
         5 . The fuel additive of  claim 1  wherein the polyisobutylene of the alkyl-substituted succinimide is prepared from about 850 to 2100 molecular weight polyisobutylene.  
     
     
         6 . The fuel additive of  claim 1  wherein the polyisobutylene of the alkyl-substituted succinimide is prepared from about 850 to 1300 molecular weight polyisobutylene.  
     
     
         7 . The fuel additive of  claim 1  wherein the polyisobutylene of the alkyl-substituted succinimide is prepared from about 950 molecular weight polyisobutylene.  
     
     
         8 . The fuel additive of  claim 1  wherein the composition comprises an organometallic complex of manganese, an overbased calcium sulfonate detergent, and an ashless alkyl-substituted succinimide dispersant such that when the additive composition is dissolved in a distillate fuel, the following relationship is satisfied:  
         −0.159 x+ 0.243 y− 0.0143 xy≦− 8.4  
       where 
 x=concentration of succinimide (in pounds per thousand barrels)  
 y=concentration of overbased calcium sulfonate (in PTB)  
 with the following limitations:  
 x=20-35, and y=10-120.  
 
     
     
         9 . The fuel additive of claim I wherein the overbased calcium sulfonate has a TBN of above about 200.  
     
     
         10 . The fuel additive of  claim 1  wherein the overbased calcium sulfonate has a TBN of about 300.  
     
     
         11 . A fuel comprising a major amount of a middle distillate fuel and a minor amount of a fuel additive composition comprising an organometallic manganese compound, an alkyl-substituted succinimide ashless dispersant, and an overbased calcium sulfonate detergent of TBN about 300.  
     
     
         12 . A method for improving the cleanliness of a fuel intake systems by use in the fuel intake system of a fuel containing a distillate fuel additive composition comprising an organometallic manganese compound, an alkyl-substituted succinimide ashless dispersant, and an overbased calcium sulfonate detergent of TBN about 300.