Electrochemical Depolymerization of Lignin in a Biomass‐based Solvent

• Published in: ChemSusChem Vol. 15; no. 15; pp. e202200718 - n/a
• Main Authors: Cruz, Márcia G. A., Gueret, Robin, Chen, Jianhong, Piątek, Jędrzej, Beele, Björn, Sipponen, Mika H., Frauscher, Marcella, Budnyk, Serhiy, Rodrigues, Bruno V. M., Slabon, Adam
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 05.08.2022
• Subjects: Biomass; coating; Depolymerization; electrocatalysis; Electrocatalysts; Hydrogen evolution reactions; Levulinic acid; Lignin; Lignocellulose; Mass spectrometry; NMR spectroscopy; Solvents; lignin; coating; electrocatalyzed depolymerization; lignin depolymerization; levulinic acid
• ISSN: 1864-5631; 1864-564X; 1864-564X
• DOI: 10.1002/cssc.202200718

Breaking down lignin into smaller units is the key to generate high value‐added products. Nevertheless, dissolving this complex plant polyphenol in an environment‐friendly way is often a challenge. Levulinic acid, which is formed during the hydrothermal processing of lignocellulosic biomass, has been shown to efficiently dissolve lignin. Herein, levulinic acid was evaluated as a medium for the reductive electrochemical depolymerization of the lignin macromolecule. Copper was chosen as the electrocatalyst due to the economic feasibility and low activity towards the hydrogen evolution reaction. After depolymerization, high‐resolution mass spectrometry and nuclear magnetic resonance spectroscopy revealed lignin‐derived monomers and dimers. A predominance of aryl ether and phenolic groups was observed. Depolymerized lignin was further evaluated as an anti‐corrosion coating, revealing enhancements on the electrochemical stability of the metal. Via a simple depolymerization process of biomass waste in a biomass‐based solvent, a straightforward approach to produce high value‐added compounds or tailored biobased materials was demonstrated. Lignin breakdown: The valorization of lignin is key to generate value‐added compounds. For this, high‐yield and green strategies to convert lignin to fine chemicals are intensively investigated. A reductive electrochemical route provides a feasible and sustainable way to obtain lignin‐derived aromatic monomers and dimers from the solubilization and further depolymerization of lignin in levulinic acid, a biomass‐based solvent.