Iron-containing fuel additive for reducing particulates generated during combustion

Abstract

The burn properties of hydrocarbon fuels are improved by incorporating bimetallic fuel additives. The fuel additives include oil-soluble iron as a primary metal component and an oil-soluble platinum-group metal as a secondary metal component. The concentration of the platinum-group metal in the fuel additive is significantly less (e.g., an order of magnitude less) than the concentration of iron. The minute amount of platinum-group metal in combination with 1 to 100 ppm iron synergistically improves smoke point and/or utilizes less iron to achieve the same improvement in smoke point as compared to iron-based fuel additives without a platinum-group metal. The additives can also include one or more oil-soluble metal compound including an alkali metal, alkaline earth metal, lanthanide metal, actinide metal, or base transition metal such as manganese.

1 . A fuel mixture suitable for use in an engine, comprising:
 a liquid hydrocarbon fuel; and   a fuel additive dissolved in the liquid hydrocarbon fuel, the fuel additive comprising:
 at least one oil-soluble iron compound present in the hydrocarbon in a range from about 1 ppm to about 100 ppm; and 
 at least one other oil-soluble transition metal compound present in the hydrocarbon in an amount less than about 100 ppm. 
   
     
     
         2 . A fuel mixture as in  claim 1 , in which the hydrocarbon fuel is selected from the group consisting of diesel fuel, jet fuel, gasoline, and biodiesel. 
     
     
         3 . A fuel mixture as in  claim 1 , in which the oil-soluble iron compound is present in the hydrocarbon in a range from about 2 ppm to about 50 ppm. 
     
     
         4 . A fuel mixture as in  claim 1 , in which the oil-soluble iron compound is present in the hydrocarbon in a range from about 5 ppm to about 30 ppm. 
     
     
         5 . A fuel mixture as in  claim 1 , in which the at least one other oil-soluble transition metal compound comprises an oil-soluble platinum-group metal compound selected from the group of platinum compounds, palladium compounds, iridium compounds, and mixtures thereof. 
     
     
         6 . A fuel mixture as in  claim 5 , in which the oil-soluble platinum-group compound is present in the hydrocarbon in a range from about 0.01 ppm to about 10 ppm. 
     
     
         7 . A fuel mixture as in  claim 5 , in which the oil-soluble platinum-group compound is present in the hydrocarbon in a range from about 0.1 ppm to about 5 ppm. 
     
     
         8 . A fuel mixture as in  claim 5 , in which the oil-soluble platinum-group compound is present in the hydrocarbon in a range from about 0.2 ppm to about 3 ppm. 
     
     
         9 . A fuel mixture as in  claim 5 , in which the oil-soluble platinum-group compound is a organometallic complex of diphenyl acetylacetonate, dibenzylidene acetonates, a fatty acid soap, or combination thereof. 
     
     
         10 . A fuel mixture as in  claim 1 , in which the at least one other oil-soluble transition metal compound comprises manganese. 
     
     
         11 . A fuel mixture as in  claim 1 , further comprising at least one additional oil-soluble metal compound selected from the group of alkaline earth metal compounds, alkali metal compounds, rare earth metal compounds, lanthanum series metal compounds, actinide series metal compounds, and mixtures thereof. 
     
     
         12 . A fuel mixture as in  claim 1 , in which the fuel additive consists essentially of the iron compound and at least one of a manganese compound or a platinum group metal compound, and optionally at least one of an alkaline earth metal compound or a lanthanide series metal compound. 
     
     
         13 . A fuel mixture as in  claim 1 , in which the oil-soluble iron compound and the at least one other transition metal compound are metal salts of an organic molecule having from 2 to 18 carbon atoms. 
     
     
         14 . A fuel mixture as in  claim 1 , in which the oil-soluble iron compound and the at least one other transition metal compound are metal salts of at least one of butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, decanoic acid, 2-ethyl butanoic acid, 2-methyl pentaoic acid, naphthenoic acid, acetyl acetonate, or 2-ethyl hexanoic acid. 
     
     
         15 . An oil soluble fuel additive for mixing with a liquid hydrocarbon fuel for reducing smoke during combustion of the hydrocarbon fuel, the additive comprising:
 an oil-based solvent;   an oil-soluble iron compound dissolved in the solvent;   at least one other oil-soluble transition metal compound dissolved in the solvent selected from the group of platinum-group metal compounds, manganese, cerium, and mixtures thereof; and   optionally, an additional metal compound dissolved in the solvent, the additional metal compound comprising a metal selected from the group consisting of an alkaline earth metal, a rare earth metal, a lanthanum series metal, or an actinide series metal.   
     
     
         16 . An additive as in  claim 15 , wherein the at least one other oil-soluble transition metal compound comprises an oil-soluble platinum-group metal compound selected from platinum compounds, palladium compounds, iridium compounds, and mixtures thereof, wherein the molar ratio of the iron compound to the platinum-group compound is in a range from about 1:10,000 to about 1:10. 
     
     
         17 . An additive as in  claim 12 , in which the solvent is mineral oil. 
     
     
         18 . An additive as in  claim 12 , in which the oil-soluble iron compound is in a concentration from about 0.01% to about 1% by weight of the fuel additive. 
     
     
         19 . A liquid fuel suitable for use in a jet turbine engine, comprising:
 a jet-fuel-grade kerosene; and   a fuel additive dissolved in the kerosene, the fuel additive comprising:
 an oil-soluble iron compound present in the hydrocarbon in a range from about 1 ppm to about 50 ppm; 
 an oil-soluble platinum-group compound selected from the group of Pt compounds, Pd compounds, Ir compounds, and mixtures thereof, the platinum-group compound being present in the liquid fuel in a range from about 0.01 ppm to about 10 ppm; and 
   at least one of an oil-soluble manganese compound or a magnesium compound present in the liquid hydrocarbon in a range from about 1 ppm to about 100 ppm.   
     
     
         20 . A liquid fuel as in  claim 19 , in which the oil-soluble iron compound, the platinum-group compound, and the optional additional metal compound are metal salt of an organic molecule having between 2 and 18 carbon atoms. 
     
     
         21 . A liquid fuel as in  claim 19 , in which the oil-soluble iron compound and the optional additional metal compound are metal salts of butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, decanoic acid, 2-ethyl butanoic acid, 2-methyl pentaoic acid, naphthenoic acid, acetyl acetonate, or 2-ethyl hexanoic acid. 
     
     
         22 . A liquid fuel suitable for use in a jet turbine engine, comprising:
 a jet-fuel-grade kerosene; and   a fuel additive dissolved in the kerosene, the fuel additive consisting essentially of:
 an oil-soluble iron compound present in the hydrocarbon in a range from about 1 ppm to about 50 ppm; 
 an oil-soluble manganese compound present in the liquid hydrocarbon in a range from about 1 ppm to about 100 ppm; and 
 optionally, at least one of an oil-soluble platinum-group compound, an alkaline earth metal compound, or cerium.