Catalytic valorization of corncob lignin using comparative Organosolv and mechano-enzymatic pretreatments

Traditional lignin valorization often relies on harsh solvent-based pretreatments that compromise carbohydrate recovery and catalyst efficiency. This study investigates the catalytic valorization of corncob lignin (1% Ruthenium) by comparing traditional Organosolv with a sustainable mechano-enzymatic (HCR-Laccase) pretreatment of corncob biomass. HPLC-UV and FTIR characterization revealed that the HCR-Laccase regime significantly improved monosaccharide preservation, particularly of glucose and xylose, compared with the degradative effects of Organosolv delignification. After depolymerization with a 1% Ru/C catalyst, we performed a comprehensive multi-phase product analysis. Notably, GC-MS profiling identified 86 metabolites in the liquid phase, highlighting a unique hybrid, high-value chemical composition in the HCR-Ru stream, rich in both lignin-derived phenolics (e.g., 3-Ethylphenol) and carbohydrate-derived polyols, with better preservation of syringyl (S) units. Despite a higher initial oxygen-to-carbon ratio in the HCR-LccH pretreated feedstock (O/C = 0.43), the Ru catalyst achieved a net Degree of Deoxygenation (DOD) of +9.3%, outperforming the Organosolv-Ru system (−5.1%). Van Krevelen analysis confirmed a significant chemical shift toward deoxygenated aromatics across both pretreatments. These results suggest that the mechano-enzymatic approach minimizes carbohydrate degradation pathways (furfural/5-HMF) that typically condense into pseudo-lignin structures, thereby enhancing catalytic responsiveness. This integrated strategy facilitates the valorization of lignocellulosic biomass, offering a viable solvent-free alternative and a robust pathway for the simultaneous production of aromatic monomers and platform chemicals in a circular biorefinery model.