One-step alcoholysis of lignin into small-molecular aromatics: Influence of temperature, solvent, and catalyst

• Main Authors: Fang Wang, You-Zhu Yu, Yigang Chen, Chun-Yu Yang, Yuan-Yu Yang
• Format: Article
• Language: English
• Published: Elsevier 2019-12-01
• Series: Biotechnology Reports
• Online Access: http://www.sciencedirect.com/science/article/pii/S2215017X19302267

Lignin valorization is a challenge because of its complex structure and high thermal stability. Supercritical alcoholysis of lignin without external hydrogen in a self-made high-pressure reactor is investigated under different temperatures (450–500 °C) and solvents as well as catalysts by using a reactant suspension mode. Small-molecular arenes and mono-phenols (C7-C12) are generated under short residence time of 30 min. High temperature (500 °C) favors efficient deoxy-liquefaction of lignin (70%) and formation of small-molecular arenes (C6-C9). Solvents methanol and ethanol demonstrate much more synergistic effect on efficient deoxy-liquefaction of lignin than propanol. The catalyst Cu-C has the optimal activity and selectivity in methanol (70% of conversion, 83.93% of arenes), whereas Fe-SiC possesses the optimal catalytic deoxygenation in ethanol, resulting in the formation of arenes other than phenols. Further analysis indicates that lignin is converted into arenes by efficient cleavages of CO ether bonds and CC bonds under high temperature and pressure. Keywords: Lignin, Arenes, Alcoholysis, Aromatics, Deoxy-liquefaction