Catalytic pyrolysis of pinewood using metal oxide catalysts in an integrated reactor system

Catalytic fast pyrolysis is a technology that has been widely explored in the past decade for direct conversion of solid biomass to partially upgraded bio-oil containing hydrocarbons. Zeolites, both unpromoted and promoted with metal ions, have been the most widely studied catalysts. As the yield and composition of the bio-oils from catalytic pyrolysis are a function of the catalyst employed, exploring catalyst compositions other than zeolites is necessary. Our study explored metal oxide catalysts, including sulfated zirconia, tungstated zirconia, zirconiatitania and titania (anatase and rutile), for catalyzing pinewood pyrolysis vapors; pyrolysis was carried out at 450 degrees C, while the catalysis was performed at 425 degrees C, at a weight hourly space velocity of 14 h(-1). The liquid, solid (char) and gas yields varied from 36.3 to 45.2%, 15.6 to 17% and 44.3 to 37.7%, respectively. The characterization of the catalyzed bio-oils showed that the most effective, among the tested catalysts, for catalyzing the pinewood pyrolysis vapors to produce partially deoxygenated bio-oils was sulfated zirconia catalyst with bio-oil yields of 39.5%. Sulfated zirconia catalyzed bio-oil possessed 33% lower oxygen content, 56% higher heating value (HHV), and 51% lower acid value compared to uncatalyzed bio-oil. Titania catalysts favored higher bio-oil yields, with titania-rutile and titania-anatase resulting in 43% and 45% bio-oil yield, respectively.