Converting lignin into long-chain fatty acids with the electro-Fenton reaction

The lack of effective lignin valorization technology remains a major barrier to utilize lignocellulose for producing biofuels and biochemicals. In this work, a new technology via the three-phase three-dimensional electro-Fenton reaction was employed for the first time to convert lignin or its derived aromatics. The operating parameters were optimized by central composite design, which was controlled to prompt the synthesis of long-chain fatty acids from lignin instead of degrading lignin to CO2. Under the optimized condition, the yields of palmitic acid and octadecanoic acid from lignin reached 138.41 and 112.31 mg/g, respectively. Key intermediators were identified during the electrolysis of lignin model compound using gas chromatography-quantitative time of flight mass spectrometry. The mechanism for the production of long-chain fatty acids from lignin was proposed. Lignin successively underwent degradation, opening ring, and couple reactions and produced free radicals. This study is the first to report the conversion of lignin into the precursor of biodiesel or advanced biofuels through electro-Fenton electrolysis at room temperature and atmosphere pressure. This study provides an environment-friendly route for direct conversion of lignin into high-value added products as a new strategy to valorize this undervalued component in lignocellulosic biomass.

Automated summary

The lack of effective lignin valorization technology is a major barrier to utilizing lignocellulose for biofuels and biochemicals. This study introduces a new technology using electro-Fenton reaction to convert lignin into long-chain fatty acids, offering an environment-friendly route for the direct conversion of lignin into high-value added products.