Biodiesel production from refined sunflower vegetable oil over zeolite supported catalysts

Abstract

This work focuses on the production of biodiesel, a renewable source of energy, via transesterification of refined sunflower oil using potassium hydroxide (KOH) supported on ZSM5 zeolite as alkaline solid catalyst. ZSM5 zeolite was impregnated with different KOH loadings (15 wt. %, 25 wt. % and 35 wt. %). The catalysts were calcined at 500 °C for 3 hours before characterization by N2 adsorption-desorption, XRD and XRF techniques. All the catalytic reactions were performed in a batch reactor at 60°C and under atmospheric pressure. It was found that KOH/ZSM5 with 35 wt. % loading showed the best catalytic performance. Optimization of the reaction conditions in the presence of KOH/ZSM5 (35 wt. %) was done by modifying the catalyst to oil ratio and the reaction time. The highest methyl ester yield (> 95%) was obtained after a reaction time of 24 hours, a catalyst to oil ratio of 18 wt. %and a methanol to oil molar ratio of 12:1. Characterization of the spent catalyst was done using X-Ray fluorescence (XRF), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) techniques in order to study its aging characteristics after four consecutive runs. The catalytic stability test showed that 35KOH/ZSM5 was stable for 3 consecutive runs. The physical and chemical properties of produced biodiesel were in good accordance with the ASTM D675 requirements. In the scale up study, 35KOH/ZSM5 showed to be a promising heterogeneous catalyst for biodiesel production in industries.