A kinetic study on the hydrolysis of corncob residues to levulinic acid in the FeCl₃–NaCl system

Levulinic acid (LA) production from corncob acid hydrolysis residues (CAHR) using FeCl₃ as Lewis acid catalyst in green solutions of salt was investigated. The reaction kinetic relationships were determined in the temperature range of 160–180 °C, with FeCl₃ concentrations of 0.12–0.36 M, and a reaction time of 0–60 min. The maximum LA concentration of 59.0 mol% (24.5 g/L) was achieved at 170 °C in a 30% NaCl solution containing 0.24 M FeCl₃. A pseudo first-order kinetic model was proposed to describe the cellulose deconstruction to LA. The model agreed perfectly with the evolution in the concentrations of the major compounds such as glucose, 5-hydroxymethylfurfural and LA during the CAHR hydrolysis. The kinetic model developed for CAHR was in good agreement with that previously developed for other lignocellulosic systems. Based on our kinetic model and reaction system, the LA yield is increased at the lower end of the temperature range with the higher acid concentrations. The results indicated that the concentrated seawater after desalination could be a green solvent in the biorefinery.