Production of Levulinic Acid and Furfural by Microwave-Assisted Hydrolysis from Model Compounds: Effect of Temperature, Acid Concentration and Reaction Time

Abstract

In this study a system for the production of levulinic acid and furfural from lignocellulosic polysaccharides was investigated using cellulose and xylan as model compounds. The goal was to determine the optimum process conditions for a dilute acid hydrolysis of cellulose and xylan to levulinic acid and furfural, respectively. The yields of levulinic acid and furfural were investigated by optimization of the main process parameters, i.e., HCl concentration (cHCl), reaction temperature (T) and reaction time (t), via Response Surface Methodology. The reaction rate was increased by the use of microwave irradiation as an efficient heating method, allowing significant energy and time savings. The following optimal conditions for the conversion of cellulose to levulinic acid were obtained: T of 200 °C, t of 3.32 min and cHCl of 1.37 M. Similarly, the optimal conditions for the conversion of xylan to furfural were: T of 195 °C, t of 1 min and cHCl of 0.36 M. The value of all three process variables under scrutiny were higher for the production of levulinic acid. It can hence be concluded that (i) the optimal conversion of cellulose and xylan takes place at different process conditions, hampering the simultaneous conversion of both components present in lignocellulosic biomass, (ii) a further optimization of the process parameters is needed. However, the overall results of this study provide useful information to developing more cost-effective and efficient systems for the production of platform chemicals from lignocellulosic biomass.