Catalytic conversion of biomass to bio-syncrude oil

Abstract

The conversion of biomass to transportation fuels and chemicals has been of immense interest in recent years. In this study, the production of high quality bio-oil (bio-syncrude oil) was achieved by catalytically cracking pyrolysis vapors from hybrid poplar in a dual-fluidized bed reactor. The catalytic deoxygenation of the primary pyrolysis vapors was achieved with a commercial HZSM-5 at 425–450°C. The organic, water, char, coke, and gas yields were 11.9, 20.9, 16.5, 3.8, and 46.8 wt.%, respectively. This work demonstrated that the use of a fluidized bed reactor for the catalytic upgrading reduces coke formation and increases catalyst lifetime. The concentration of the permanent gases was in the order of CO > CO2 > C3H6 > CH4 > H2 > other C2–C4. The light bio-syncrude (LBS) oil collected from the condenser was predominately aromatic hydrocarbons. The heavy bio-syncrude (HBS) oil collected from the electrostatic precipitator consisted of mainly phenols, methyl-substituted phenols, naphthalenes, benzenediols, and naphthalenol. The bio-syncrude oils were low in oxygen, less viscous, less acidic, stable, and high in energy density. The higher heating value of the light and heavy bio-syncrude oil was 36.89 and 33.98 MJ/kg, respectively. The distillate yields from the atmospheric distillation showed that 91 wt.% of the LBS oil distills up to 220°C and 76 wt.% of the HBS oil distills up to 440°C. Accelerated stability test of the oils at 90°C for 24 h and storage of the oils at room temperature for 10 months showed that the bio-syncrude oils were stable. The catalytic deoxygenation of the pyrolysis vapors resulted in the removal of undesirable oxygenates such as levoglucosan, carboxylic acids, aldehydes, and ketones. The bio-syncrude oil can be considered as a suitable feed for use in a petroleum refinery for the production of transportation fuels and chemicals.