Catalytic conversion of lignocellulosic biomass to levulinic acid in ionic liquid

Abstract

The catalytic conversion of lignocellulosic biomass to levulinic acid in ionic liquid, [EMIM][Cl] was conducted using a hybrid catalyst. The hybrid catalyst (1:1 ratio) with equal CrCl3 and HY zeolite weight ratios was synthesized using a wet impregnation method. Initially, optimization of cellulose as a model compound was carried out using two-level full factorial design (23) with two centre points. Under optimum process conditions, 46.0% of levulinic acid yield was produced from cellulose. Subsequently, utilization of lignocellulosic biomass demonstrated 15.5% and 15.0% of levulinic acid yield from empty fruit bunch (EFB) and kenaf, respectively, at the optimum conditions. Meanwhile, in the presence of ionic liquid under the same process conditions, 20.0% and 17.0% of levulinic acid were obtained for EFB and kenaf, respectively. The results indicated that ionic liquid could disrupt the covalent linkages between the biomass structures and dissolved the hollocellulose. This allowed the hollocellulose chains, accessible to the chemical transformation, to react and produce levulinic acid in presence of the hybrid catalyst. This study demonstrated that the combination of hybrid catalyst and ionic liquid has the potential to be applied for biomass conversion to levulinic acid under adequate process conditions.