Biodiesel Production from Free Fatty Acid using ZrO 2/Bagasse Fly Ash Catalyst

This study utilizes ZrO2/Bagasse Fly Ash as a solid catalyst to convert Free Fatty Acid (FFA) from Palm Fatty Acid Distillate (PFAD) into biodiesel. The ZrO2/Bagasse fly ash catalyst was characterized by several physicochemical techniques, i.e., N-2 adsorption-desorption, X-ray diffraction (XRD), and X-ray fluorescent (XRF). The catalyst was then applied for FFA esterification under different conditions. The highest FFA esterification conversion was 90.6%, which was reached at the optimal reaction condition as follows: methanol/PFAD mass ratio of 10:1; catalyst amount of 10 wt%; and reaction temperature of 60 degrees C. It was also found that the catalyst could be reused up to four times by an activation process. This study presented the Eley-Rideal kinetic model to describe the reaction mechanism. The model demonstrated an excellent fit to the experimental result with an R-2 value of 0.99, showing that Eley-Rideal is a valid model to describe the reaction and that the surface reaction step acts as the rate-determining step. Additionally, the reaction kinetics and adsorption equilibrium parameters were determined using non-linear regression. The correlation between the parameters with temperature was evaluated using Arrhenius and van't Hoff equations.