Esterification of levulinic acid to ethyl levulinate using liquefied oil palm frond-based carbon cryogel catalyst

• Main Authors: Mohammad Zainol, Muzakkir, Saidina Amin, Nor Aishah, Mohd. Asmadi, Mohd. Asmadi, Ramli, Nur Aainaa Syahirah
• Format: Article
• Published: Springer New York LLC 2019
• Subjects: TP Chemical technology
• Online Access: http://eprints.utm.my/id/eprint/89121/; http://dx.doi.org/10.1007/s12155-019-09977-6
• Institution: Universiti Teknologi Malaysia

Oil palm biomass, which is abundantly available in Malaysia, has many types of applications in various industries. In this study, oil palm frond (OPF) was liquefied with 1-butyl-3-methylimidazole hydrogen sulfate ([BMIM][HSO4]) ionic liquid (IL) at optimum conditions. The liquefied OPF-ionic liquid (LOPF-IL) was mixed with furfural at a ratio of 0.8 (w/w), water-to-feedstock ratio of 0.125 (w/w), and sulfuric acid loading of 0.5 mL at 100 °C for 1 h to form a gel. Carbon cryogel liquefied oil palm frond (CCOPF) was prepared using a freeze-dryer followed by calcination. CCOPF was further characterized using N2 sorption, NH3-TPD, TGA, XRD, FTIR, and FESEM to determine its physical and chemical properties. The thermally stable CCOPF exhibited a large total surface area (578 m2/g) and high total acidity (17.6 mmol/g). Next, CCOPF was tested for levulinic acid catalytic esterification by varying the parameters including ethanol-to-levulinic acid molar ratio, catalyst loading, and reaction time at 78 °C. At the optimum conditions, the conversion of levulinic acid and ethyl levulinate yield was 70.9 and 71.7 mol%, respectively. CCOPF was reusable up to five runs with no significant conversion drop. Accordingly, CCOPF is conferred as a potential biomass-derived acid catalyst for ethyl levulinate production.