Ultrasound acoustic cavitation enhances depolymerization of organosolv lignin to phenolic monomers and low molecular weight lignin bio-oils

Lignin-first is a strategy for producing value-added phenolics and high-quality bio-oils from lignin. To contribute to this strategy, we investigated the effects of ultrasound acoustic cavitation on depolymerization of organosolv lignin to phenolic monomers and low molecular weight lignin bio-oils. We achieved the highest lignin bio-oil yield of 56.9 wt% at a temperature of 250 °C, a reaction time of 6 h, and an ultrasonic power of 90 W. Moreover, the obtained lignin bio-oils had low molecular weight, narrow molecular weight distribution and lack of ether linkages, which are the characteristics suitable as a source of liquid bio-oil fuels. Finally, the prominent phenolic monomers in liquid bio-oil, including phenol , 2-(1-methylethyl)-phenol and benzene, 1,2,3-trimethoxy-5-methyl, were identified in lignin bio-oil.