Industrial & Engineering Chemistry Research, Vol.51, No.31, 10313-10319, 2012
Preparation of a Research Jet Fuel Composition Comprised of Nearly Exclusively Methyl-Branched Tetradecane Isomers Having a Freezing Point below-47 degrees C
The potential for a variety of biologically derived alternative aviation fuels continues to be investigated. The composition of some of these potential fuels contains only a limited number of isomers of only one carbon number. These types of alternative fuels fail the distillation distribution specification in current use. However, it is unclear whether this has actual impact on in-use performance if such an alternative blendstock were used to make a 50/50 alternative/petroleum blend. In order to investigate this question further, the U.S. Air Force seeks a generic surrogate research fuel comprised of isomers of tetradecane that meet the -47 degrees C freezing point specification of JP-8. We describe our laboratory investigation of a strategy for preparing such an isomer mixture while remaining mindful of the desire to scale the procedures for making hundreds of gallons of such a fuel. We start with a commercially available 1-tetradecene, hydrogenate the olefin to n-tetradecane, which is then hydroisomerized using a Pt/US-Y zeolite catalyst, and the raw tetradecane mixture is separated from cracked products by distillation. In order for the isomeric mixture to meet the freezing point specification, the remaining n-tetradecane content must be reduced to <1.5%. We describe a solvent dewaxing approach that achieves this goal.