Aviation Gasoline Containing Branched Aromatics with a Manganese Octane Enhancer

Abstract

An improved aviation gasoline formulation includes a branched aromatic composition to improve the Motor Octane Number of the fuel. Specifically, the branched aromatic composition includes an aromatic functional group covalently bonded to a branched alkyl group. The branched aromatic composition is used in the aviation gasoline together with a manganese-containing compound to enable the fuel to meet MON requirements.

That which is claimed is: 
     
         1 . An aviation gasoline formulation comprising:
 at least about 20 volume percent of aviation alkylate composition;   a manganese-containing compound; and   about one to 50 volume percent of aromatic composition, wherein the aromatic composition includes a branched aromatic composition that is an aromatic functional group covalently bonded to a branched alkyl group.   
     
     
         2 . An aviation gasoline formulation as described in  claim 1 , wherein the aromatic functional group is selected from the group consisting of benzene, naphthalene and anthracene. 
     
     
         3 . An aviation gasoline formulation as described in  claim 1 , wherein the aromatic functional group is a heteroaromatic group that contains an atom selected from the group consisting of oxygen, nitrogen and sulfur. 
     
     
         4 . An aviation gasoline formulation as described in  claim 1 , wherein the aromatic functional group is a 5 or 6 membered aromatic ring. 
     
     
         5 . An aviation gasoline formulation as described in  claim 1 , wherein the branched alkyl group contains 3 to 15 atoms. 
     
     
         6 . The aviation gasoline formulation as described in  claim 5 , wherein the branched alkyl group is formed entirely of carbon atoms. 
     
     
         7 . An aviation gasoline formulation as described in  claim 5 , wherein the branched alkyl group includes one or more heteroatoms selected from the group consisting of oxygen, nitrogen, sulfur, silicon, phosphorous, boron, fluorine, chlorine, bromine and iodine. 
     
     
         8 . An aviation gasoline formulation as described in  claim 1 , wherein the branched aromatic composition comprises about 1 to 25 volume percent of the aviation gasoline formulation. 
     
     
         9 . An aviation gasoline formulation as described in  claim 1 , wherein the branched aromatic composition comprises a mixture of different branched aromatic compositions. 
     
     
         10 . An aviation gasoline formulation as described in  claim 1 , wherein the branched aromatic composition is tert-butylbenzene. 
     
     
         11 . An aviation gasoline formulation as described in  claim 1 , wherein the amount of manganese-containing compound is present in 500 mg Mn/L or less, and the Motor Octane Number (MON) of the aviation gasoline is at least 99.6. 
     
     
         12 . An aviation gasoline formulation as described in  claim 1 , wherein the aromatic composition is present in the amount of 30 volume percent of the gasoline formulation or less, and the Motor Octane Number (MON) of the aviation gasoline is at least 99.6. 
     
     
         13 . A method of reducing the amount of manganese-containing engine deposits formed in the combustion of an aviation gasoline formulation, the method comprising the steps of:
 providing a first aviation gasoline formulation that comprises at least about 20 volume percent of aviation alkylate composition, a first amount of a manganese-containing compound, and about one to 50 volume percent of an unbranched aromatic compound;   prior to mixing the first aviation gasoline formulation, preparing a second aviation gasoline formulation by substituting a branched aromatic composition for at least about 25 volume percent of the unbranched aromatic compound and at the same time incorporating only a second amount of manganese-containing compound that is less that the first amount of manganese-containing compound;   wherein the combustion of the second aviation gasoline formulation results in the formation of less manganese-containing engine deposits than the combustion of the first aviation gasoline formulation.