Hydrocracking of Algae Oil into Aviation Fuel-Range Hydrocarbons Using a Pt-Re Catalyst

Renewable green aviation and diesel-type alkanes can be produced by hydrocracking of Botryococcus braunii oil (Bot-oil) and squalane oils with PtRe/SiO2Al2O3 (SA) catalysts, which are active at 310-340 degrees C and the weight ratio of the oil/catalyst of 10. For purified Bot-oil on Pt3 wt % Re/SA at 330 degrees C, the highest aviation fuel-range hydrocarbon (C10C15) yield of 50.2% was achieved, with diesel-range hydrocarbons (C16C20) of 16.7% yield. The re-modified Pt/SA catalysts are also active for hydrocracking of squalane as the model compound of algae oil, and the C10C20 hydrocarbon yield of 68.8% was obtained. The PtRe catalyst was found to be stable for the second regeneration cycle, even with the use of crude Bot-oil. Investigation of catalyst natures indicates that metallic Pt and Re are independently present on the surface, but synergism of these two metals could play an important role in the hydrocracking reaction. The reaction pathway involves the CC bond scission reaction via a carbenium ion formed from one of the double-bond carbons over the SA catalyst, followed by hydrogenation of the C=C and C-C bonds by the PtRe catalyst and partial aromatization over the SA catalyst.