Unleaded gasoline formulations for piston engines

Abstract

Disclosed herein are fuel formulations comprising C 4 -C 12 aliphatic hydrocarbons and cumidine. In embodiments, the formulations further include a limited amount of aromatic hydrocarbons. In other embodiments, the aliphatic hydrocarbons are alkylates, and in still other embodiment the alkylates are alkanes. These fuel formulations provide unique and advantageous physical properties suitable for piston engines.

1 . A piston engine fuel formulation comprising:
 about 80 to about 99 wt % C 4 -C 12  aliphatic hydrocarbons;   about 1 to about 20 wt % cumidine; and   less than about 5 wt % C 6 -C 12  aromatic hydrocarbons,   said fuel formulation being substantially free of lead-containing constituents.   
     
     
         2 . The fuel formulation of  claim 1  being substantially free of C 6 -C 12  aromatic hydrocarbons. 
     
     
         3 . The fuel formulation of  claim 1  consisting essentially of:
 about 80 to about 99 wt % C 4 -C 12  aliphatic hydrocarbons; and 
 about 1 to about 20 wt % cumidine. 
 
     
     
         4 . The fuel formulation of  claim 1  consisting essentially of:
 about 85 to about 95 wt % C 4 -C 12  aliphatic hydrocarbons; and 
 about 5 to about 15 wt % cumidine. 
 
     
     
         5 . The fuel formulation of  claim 1  comprising a MON of at least about 100 and an RVP of 38 to 49 kPa at 37.8° C. 
     
     
         6 . The piston engine fuel formulation of  claim 1  comprising:
 about 80 to about 99 wt % C 4 -C 10  alkylates; 
 about 1 to about 20 wt % cumidine; and 
 less than about 5 wt % C 6 -C 12  aromatic hydrocarbons. 
 
     
     
         7 . The piston engine fuel formulation of  claim 1  comprising:
 about 80 to about 99 wt % C 4 -C 10  alkanes; 
 about 1 to about 20 wt % cumidine; and 
 less than about 5 wt % C 6 -C 12  aromatic hydrocarbons. 
 
     
     
         8 . The fuel formulation of  claim 7  comprising:
 about 80 to about 99 wt % isobutane, isopentane and/or isooctane and about 1 to about 20 wt % cumidine. 
 
     
     
         9 . The fuel formulation of  claim 8  in which said cumidine is 4-isopropylaniline. 
     
     
         10 . The fuel formulation of  claim 9  comprising about 85 to about 95 wt % of isobutane, isopentane and/or isooctane and about 5 to about 15 wt % 4-isopropylaniline. 
     
     
         11 . The fuel formulation of  claim 10  being substantially free of C 6 -C 12  aromatic hydrocarbons. 
     
     
         12 . The fuel formulation of  claim 10  consisting essentially of about 85 to about 95 wt % isobutane, isopentane and/or isooctane and about 5 to about 15 wt % 4-isopropylaniline. 
     
     
         13 . The fuel formulation of  claim 12  comprising a MON of at least about 100 and an RVP of 38 to 49 kPa at 37.8° C. 
     
     
         14 . The fuel formulation of  claim 13  comprising about 2 wt % isobutane, about 10 wt % isopentane, about 73 wt % isooctane, and about 15 wt % 4-isopropylaniline, and having a MON of about 103.5. 
     
     
         15 . The fuel formulation of  claim 14  consisting essentially of about 2 wt % isobutane, about 10 wt % isopentane, about 73 wt % isooctane, and about 15 wt % 4-isopropylaniline, and having a MON of about 103.5. 
     
     
         16 . The fuel formulation of  claim 13  comprising about 2 wt % isobutane, about 10 wt % isopentane, about 76 wt % isooctane, and about 12 wt % 4-isopropylaniline, and having a MON of about 102. 
     
     
         17 . The fuel formulation of  claim 14  consisting essentially of about 2 wt % isobutane, about 10 wt % isopentane, about 76 wt % isooctane, and about 12 wt % 4-isopropylaniline, and having a MON of about 102.