Sanja Vucetic: Aromatic platforms from industrial lignins for high-value materials production

Lignin is the largest renewable source of aromatic compounds and represents a promising raw material for the development of sustainable high-value products. In this study, lignins obtained from different industrial companies and biomass sources were investigated as feedstocks for the production of aromatic platforms via catalytic reductive depolymerization. Prior to depolymerization, sequential solvent fractionation was applied in order to isolate fractions with different solubility behavior and molecular weight distributions. Two main fractions, ethanol-soluble and ethanol-insoluble lignin, were selected for further valorization.

Depolymerization experiments were carried out in a high-pressure batch reactor using an ethanol–water solvent system and Ru/C catalyst under hydrogen atmosphere at 220°C. The obtained products were analyzed using HPSEC, 2D HSQC NMR, ³¹P NMR, and elemental analysis to evaluate structural and chemical changes after treatment. The results showed a significant decrease in molecular weight for all investigated lignin samples, confirming efficient depolymerization. In addition, spectroscopic analyses indicated a reduction of β-O-4 linkages and an increase in phenolic hydroxyl functionalities, demonstrating selective bond cleavage while preserving valuable aromatic structures.

Differences in depolymerization behavior were observed depending on lignin origin and fraction type, highlighting the importance of feedstock selection and pretreatment strategy. The obtained lignin-derived oligomeric and aromatic fractions show strong potential as renewable intermediates for the synthesis of adhesives, polymers, antioxidants, and polyurethane materials. This work demonstrates that lignins sourced from various industrial companies can serve as promising raw materials for sustainable production of high-value chemicals and materials.