Efficient recovery of high-concentration levulinic acid from batch to continuous operation using a four-zone chromatographic separation system

Efficient separation of levulinic acid (LA) from biomass hydrolysates remains a major challenge, particularly at high LA concentrations where conventional fixed-bed adsorption suffers from increased competitive adsorption, long cycle times, and high solvent consumption. This study developed a four-zone continuous chromatographic separation process using the hyper-cross-linked resin SY-01 for the recovery of high-concentration LA from simulated biomass hydrolysates. Adsorption equilibrium, competitive adsorption, and kinetic behaviors were first investigated, followed by optimization of fixed-bed adsorption and construction of a continuous chromatographic system. The separation performances of the two operating modes were then quantitatively compared under identical conditions. SY-01 exhibited high adsorption capacity and rapid adsorption kinetics toward LA, while the continuous system achieved stable operation with a peak LA concentration of 321.15 g/L (3.21-fold enrichment). Compared with conventional fixed-bed adsorption, continuous operation reduced cycle time by 86.8%, ethanol consumption by 65.7%, and water consumption by 40.0%, while substantially increasing process throughput. These results demonstrate that integrating SY-01 with four-zone continuous chromatography provides an efficient, economical, and environmentally friendly strategy for industrial recovery of high-concentration levulinic acid.