Zeolite catalysts screening for production of phenolic bio-oils with high contents of monomeric aromatics/phenolics from hydrolysis lignin via catalytic fast pyrolysis

In this work, zeolite catalysts, widely used catalysts for effectively cracking of organics into highly deoxygenated and hydrocarbon-rich compounds, were screened for their performance in catalytic fast pyrolysis (CFP) of hydrolysis lignin (HL) in a drop-tube fixed bed reactor at temperatures of 400, 450, and 500 °C. Five commercial zeolite catalysts including zeolite X, Zeolite Y (CBV-100, CBV-600, and CBV-780) and ZSM-5 (CBV-8014) were screened, and ZSM-5 exhibited the best performance for converting hydrolysis lignin to monomeric aromatics/phenolics. It was demonstrated that the catalyst total acidity and the Bronsted acid sites play a key role in cracking and deoxygenation of the pyrolysis vapors towards the monomeric aromatic/phenolic hydrocarbons. CFP of HL under the best conditions (450 °C, ZSM-5 catalysts), produced bio-oil at 57.4 wt% yield, and a high yield of monomeric aromatics/phenolics (being 0.11 g/g-HL).