<br/>Lignin is the largest source of aromatic building blocks on the planet and harbors great potential to serve as starting material for the production of value-added chemicals. Herein, we describe lignin depolymerization using ethanol/iso-propanol media as H-donors and no added catalysts for this process. In this work, different ratios of ethanol/iso-propanol were evaluated for the degradation of organosolv poplar lignin. The results showed that depolymerization of lignin carried out in the mixed ethanol/iso-propanol media was more effective than the reaction in ethanol or iso-propanol alone. More than 75 wt% of bio-oil yield including highest monomer yield can be obtained by heating in ethanol/iso-propanol (50:50) media in a closed vessel at 270 °C for 4 h (Fig. 1). Among the monomers, the yield of (E)-4-propenyl syringol was the highest (18.5 wt%), followed by isoeugenol (2.5 wt%), which were carefully characterized by gas chromatography (GC-MS), high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR). In addition, the study on lignin model compound (guaiacylglycerol-β-guaiacyl ether) showed that the decomposition of lignin model compound in ethanol/iso-propanol was significantly accelerated the presence of a small amount of added lignin (Fig. 2), implying that lignin itself may act as a “catalyst” in this process.

Efficient depolymerization of organosolv lignin in ethanol/iso-propanol media without catalyst

2019 Fall National Meeting

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