Levulinic acid production from lignocellulosic biomass using hy zeolite supported chromium catalyst in ionic liquid

Abstract

Levulinic acid is a sugar-derived building block that can be produced from biomass feedstock as an alternative to the petrochemical resources. The purpose of this study was to investigate the performance of HY zeolite supported chromium catalysts in producing levulinic acid from glucose, cellulose and lignocellulosic biomass before it was further optimized using response surface methodology (RSM). The catalysts comprising of different weight ratios of CrCl3 and HY zeolite (1:1, 1:2 and 2:1) were synthesized using wetness impregnation method. Characterization of the catalysts using XRD, BET, FT-IR, TGA, NH3-TPD and FT-IR of adsorbed pyridine demonstrated the catalytic reaction of the catalysts was predominantly influenced by type (Lewis acid), amount and strength of acid sites, surface area, hierarchical porous structures and shape selectivity of the catalysts. Experimental results showed that the CrC3/HY–1:1 catalyst exhibited the highest catalytic performance with 62% levulinic acid yield at reaction temperature, 160 ºC and reaction time, 180 min. Optimization of levulinic acid was conducted using the potential CrC3/HY–1:1 catalyst and ionic liquid, [EMIM][Cl] was introduced as a solvent for the cellulose conversion to levulinic acid. At optimum process conditions, 55.2%, 46.0%, 15.5% and 15.0% of levulinic acid yields were produced from glucose, cellulose, empty fruit bunch (EFB) and kenaf. Meanwhile, in the presence of ionic liquid under the same process conditions, 20.0% and 17.0% of levulinic acid yields were produced from EFB and kenaf. In addition, the compositions of EFB and kenaf were determined to compute the highest theoretical levulinic acid yields in the samples feedstock and the efficiencies of the catalytic process. This study demonstrated that the combination of the proposed catalyst with ionic liquid has potential to be applied in biomass conversion to levulinic acid under adequate process conditions.