Novel Fractionation-Depolymerization Control of Rapid Dissociation of Lignin-Associated Xylan: Toward Complete Lignocellulosic Biomass Valorization in Lignin-first Biorefinery

Abstract

Harvesting sustainable aromatic chemicals from lignocellulosic biomass is a critical subject of the bio-based economy. Ideal whole-biomass utilization strategies have been developed for lignin valorization via solvent fractionation followed by catalytic hydrogenolysis. However, the limited understanding on lignin/hemicellulose structure and lack of control strategy on side reactions has seriously hindered the applicability of those novel biorefinery techniques. To overcome this challenge, this study integrated various solution- and solid-state Nuclear Magnetic Resonance (NMR) techniques with 66 biorefinery and hydrogenolysis experiments, aiming to construct a novel Pretreatment Depolymerization Factor (PDF) model for simulating the hydrolysis kinetics of hemicelluloses, including xylans in different conformations and arabinose residues. The PDF model successfully simulated the delignification dynamics, lignin integrities, and monolignols yield with 90.9% accuracy, leading to a new discovery of an unexplored Cβ–Cγ lignin bond cleavage initiated by Cγ–OH activation. The monolignol yield increased by over 30% through a PDF-assisted sequencing batch fractionation strategy without requiring additional solvent, energy, or chemicals, and exceeded the theoretical monomer yield attainable by batch pretreatment. This effective preservation of both carbohydrates and aromatic products highlights the economic and environmental benefits of smart fractionation control in complete lignocellulose utilization.