Single Stage Hydroprocessing of Pyrolysis Oil in a Continuous Packed-Bed Reactor

摘要

Raw bio-oil cannot be combusted as transportation fuel directly because of its high acidity, high water content, lower heating value, and variable viscosity over time. Therefore, bio-oil should be chemically converted to a more stable liquid product before subjecting it to hydrodeoxygenation (HDO) conditions. This research article focuses on catalytic hydro-processing of pretreated bio-oil (PTBO) in a single stage reaction using various catalyst compositions in a packed-bed reactor. Four catalysts, a conventional hydrotreating catalyst (CoMo/γ-Al_2O_3), an Fe-Cr based mixed oxide catalyst, an FeW/Si-Al catalyst, and a 1:2 mixture of Ru/γ-Al_2O_3 and Ni/Si-Al catalyst, were tested for conversion of the PTBO to mixed liquid hydrocarbons at 350-400℃, 1500 psig hydrogen pressure, and at a liquid hourly space velocity (LHSV) of 0.2-0.3 h~(-1). Liquid products produced from the HDO treatments were analyzed for properties such as acid value, heating value, elemental analysis, water content, and chemical characterization. The conventional hydrotreating catalyst, CoMo/γ-Al_2O_3, performed the best among the four catalysts employed to reduced the acid value to 2 mg KOH/g and oxygen content to 0.1% while improving the heating value to 43 MJ/kg of the liquid product. The detailed hydrocarbon analysis of the reduced CoMo/γ-Al_2O_3 upgraded hydrocarbon mixture showed the presence of olefins, iso-paraffins, followed by naphthenes and aromatics. Simulated distillation results indicated that the liquid fuel had a boiling point range of 69-304℃, indicating the presence of petroleum equivalents of 50% gasoline (38-170℃), 30% jet fuel (170-250℃), and 20% diesel (250-304℃) range hydrocarbons.