Keywords: lignin, Depolymerization, heterogeneous catalystLignin is the largest natural source of aromatic compounds which, and it plays a crucial role in advancing sustainable chemistry by reducing dependence on fossil resources. The ongoing study investigates the catalytic reductive depolymerization of lignin originating from various industrial sources, aiming to produce fractions tailored for high-value applications such as adhesives, polymer chemistry, antioxidants, and antimicrobial agents1, 2.The initial study on lignin depolymerization was carried out in a batch reactor using a Ru catalyst under inert (Ar) and reducing (H₂) atmospheres in an ethanol-water solution as the solvent to enhance lignin solubilization and catalytic efficiency. The main objectives were to achieve effective reductive depolymerization, characterize the resulting lignin fractions and oligomeric intermediates, and explore the potential applications of these oligomers in advanced materials1.Product analysis was performed using High-Performance Size Exclusion Chromatography (HPSEC), revealing a significant reduction in molecular weight (Mw) of the lignin fractions after depolymerization, confirming the effectiveness of the process. Additional techniques, including two-dimensional Heteronuclear Single Quantum Coherence Nuclear Magnetic Resonance (2D HSQC NMR), DiffusionOrdered Spectroscopy (DOSY), and elemental analysis, were employed to further investigate the structural changes. The DOSY results corroborated the Mw reduction observed in HPSEC, providing additional confirmation of the depolymerization process and its impact on lignin’s structure3.This work contributes to the sustainable valorization of lignin, offering a renewable alternative to fossilderived aromatics and enabling the development of environmentally friendly products. The results highlight the importance of scalable technologies for selective lignin depolymerization, offering new pathways for creating high-performance materials in a sustainable manner2,3,4