Distillate fuel compositions for improved combustion and engine cleanliness
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.