Low molecular weight compression ignition fuel

Abstract

An improved hydrocarbon-based compression ignition fuel boils in the naphtha boiling range and comprises hydrocarbons having from 5 to about 14 carbon atoms, preferably predominantly normal paraffins having chain lengths from 6 to about 12 carbons. The fuel has an average cetane number ranging from 40 to 80 and a Reid vapor pressure of at least 2 psig to ensure safety in handling and storage. Pentane and/or oxygenated hydrocarbons such as dimethoxymethane can be added to reduce emissions and provide sufficient vapor pressure for safe handling and storage.

We claim: The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
     
         1 . A hydrocarbon-based compression ignition fuel composition in the naphtha boiling range comprising at least two hydrocarbon compounds containing from 5 to about 14 carbon atoms, said composition having a cetane number of at least 40, and said composition further having a Reid vapor pressure of at least 2 psig.  
     
     
         2 . The fuel composition of  claim 1 , wherein said composition has a cetane number preferably in the range of about 50 to about 60.  
     
     
         3 . The fuel composition of  claim 1 , wherein said hydrocarbon compounds comprise predominantly normal paraffins having chain lengths from about 6 to about 12 carbon atoms.  
     
     
         4 . The fuel composition of  claim 1 , wherein one of said hydrocarbon compounds is pentane.  
     
     
         5 . The fuel composition of  claim 1 , said composition further comprising an oxygenated hydrocarbon containing from 2 to about 4 carbon atoms and at least one oxygen atom, in a quantity effective to reduce engine emissions when said fuel is employed in a compression ignition engine.  
     
     
         6 . The fuel composition of  claim 5 , wherein said oxygenated hydrocarbon comprises dimethoxymethane.  
     
     
         7 . The fuel composition of  claim 5 , wherein said oxygenated hydrocarbon comprises diethyl ether.  
     
     
         8 . The fuel composition of  claim 1 , said composition further comprising light straight-run naphtha.