Hydroprocessing of Biorenewable Thermal Deoxygenation Oils

Thermal deoxygenation (TDO) of neutralized biomass acid hydrolyzate, namely, levulinate and formate salt mixtures, is demonstrated to yield low oxygen bio-oils suitable for transportation fuels. The chemistry and upgrading potential are evaluated for TDO oils derived from calcium- and magnesium-neutralized model biomass acid hydrolyzate containing levulinate/formate salt mixtures at a 1:1 molar ratio. TDO oils were prepared using a 50 L semibatch reactor and analyzed for component chemistry and physicochemical properties. The TDO oils contain a broad distribution of monoaromatic and polyaromatic hydrocarbons with H:C ratio of ≅1:1. Crude oils were processed under hydrogen pressure in a vertical downflow tubular reactor, using a Ni/SiO2–Al2O3 catalyst. Sustained yields of 90+ wt % were achieved over 700 h operating without catalyst regeneration. Products were identified by GC-MS to contain primarily naphthenes, monoaromatics, partially saturated polyaromatics, and only trace oxygenates. Hydroprocessed oils were distilled into naphtha, jet, kerosene, diesel, and residual fractions and analyzed using ASTM methods for fuel properties. Results indicate that upgraded TDO oils are suitable as blend stocks for reformulated fuels.