Time-Resolved Analysis of Lignocellulose Extraction in a Biphasic, Acid-Catalyzed Flow-through System

Kinetic studies of lignocellulose fractionation clarify mechanisms of biomass deconstruction but are challenged by substrate heterogeneity. Here, flow-through biphasic OrganoCat (OrganoCatFT) was used to fractionate beech wood and Miscanthus at 140 °C, 160 °C and 180 °C with 5 min sampling. Monosaccharide time courses showed rapid hemicellulose breakdown: xylose dominated the aqueous phase yet remained incompletely extracted, peaking at approximately 10 min at 160 °C–180 °C and at 20–25 min at 140 °C. At 140 °C, galacturonic acid was unexpectedly abundant (approximately 26% of extracted sugars from beech; approximately 10% from Miscanthus), indicating enhanced pectin accessibility under OrganoCatFT. Glucose yields increased with temperature and exceeded native glucan contents in hemicelluloses, consistent with contributions from starch, hemicellulosic glucan and limited cellulose hydrolysis. Kinetic fitting for beech required fast and slow xylan fractions with Arrhenius activation energies of 105 kJ mol–1 (fast) and 144 kJ mol–1 (slow) and an increasing fast fraction, φ = 0.208–0.634 (140 °C–180 °C). Miscanthus yielded higher xylose at 160 °C (106 mg g–1 vs 37 mg g–1 at 140 °C) but lower at 180 °C (80 mg g–1) due to furfural formation; glucose stayed ≤2.4 mg g–1. Thus, biomass-specific xylan architecture governs early hydrolysis, whereas cellulose conversion is only weakly temperature dependent in this range.