Effective extraction of aromatic monomers from lignin oil using a binary petroleum ether/dichloromethane solvent

The depolymerization of lignin to high value-added aromatic monomers has attracted considerable attention. Nevertheless, an effective separation process is essential for obtaining aromatic monomers from lignin depolymerization products. In this study, a binary petroleum ether (PE)/dichloromethane (DCM) solvent was used to separate aromatic monomers from lignin oil obtained from phosphomolybdic acid (POM) catalytic oxidation. The effects of the solvent polarity and temperature on the extraction efficiency were examined. The polarity of the binary solvent mixture was adjusted by tuning the PE:DCM ratio. Using the PE/DCM (85/15) mixture as the extraction solvent, 49.0% of aromatic monomers were recovered from lignin oil; the extraction fraction contained 80% aromatic monomers. Through sequential extraction of the lignin oil three times, the aromatic monomers recovery reached 69.2%, and monomers content in the extraction fraction was improved slightly to 83.0%. Lowering the extraction temperature resulted in a higher separation efficiency of aromatic monomers. This study provides a simple and efficient way to separate aromatic monomers from lignin depolymerization products.

Automated summary

Separating aromatic monomers from lignin oil using a binary solvent mixture of petroleum ether and dichloromethane was studied, with the extraction efficiency affected by solvent polarity and temperature. By adjusting the PE:DCM ratio and conducting sequential extractions, a high recovery rate of aromatic monomers was achieved. Lowering the extraction temperature also increased the separation efficiency of aromatic monomers.