Impact of wax hydrocracking severity on product properties

Wax hydrocracking is a refining process that can be used to produce kerosene for blending to synthetic jet fuel. The impact of wax hydrocracking conditions on product properties was investigated. Wax hydrocracking was performed using a 0.5 wt.% Pt/SiO 2 –Al 2 O 3 catalyst at 310, 325, 340, 355, and 370°C, 2 MPa gauge and 340 normal m 3 · m −3 H 2 ‐to‐feed ratio. The hydrocracked product from each condition was distilled in 10°C cuts in the range 60–320°C and each distillation cut was characterized individually. Density, kinematic viscosity, cloud point, flash point, and refractive index data is reported together with product selectivity and branched‐to‐linear alkane ratio (iso/ n ‐ratio). As expected, density, viscosity, and cloud point, and iso/ n ‐ratio generally increased with increasing boiling range. For all distillation cuts, the temperature dependence of density was linear and that of kinematic viscosity was described by the MacCoull relationship in ASTM D341. Cracking conversion decreased at temperatures above 325°C, and characterization of fresh and spent catalysts by BET and thermogravimetric analysis indicated catalyst deactivation through accumulation of deposited material and loss of accessible pore structure. The C 9 –C 22 selectivity was 69 ± 4 wt.%, suggesting that hydrocracking performance was limited under the low‐pressure conditions employed. Despite this shortcoming, the >140°C distillation cuts had iso/ n ‐ratios in the range 2.6–14. For comparison, kerosenes produced by Fischer–Tropsch wax hydrocracking, which were shown to be viable for blending to synthetic jet fuels, had iso/ n ‐ratios in the range 0.4–4.6.