Optimization and kinetic study of biodiesel production from beef tallow using calcium oxide as a heterogeneous and recyclable catalyst

Abstract

• Biodiesel was produced from beef tallow animal fat. • CaO catalyst obtained from CaCO 3 provides high catalytic performance. • The independent variables of time, reaction temperature, methanol to oil molar ratio, and catalyst amount were optimized using response surface methodology five-level-four-factor central composite design. • 71.31% of biodiesel yield was obtained in optimized conditions of 8:1 methanol to oil ratio, 4% catalyst loading, 60 °C reaction temperature at 90 mins. Production of biodiesel from beef tallow animal fat has largely remained unexplored. Beef tallow is a low-cost and abundant animal fat, while calcium oxide catalyst is a renewable and highly catalytic material obtained from limestone. Therefore, this study reports on the optimization and kinetic study of biodiesel production using calcium oxide solid catalyst. Several characteristics, were determined by SEM (scanning electron microscopy), XRD (X-ray diffraction spectrometry), XRF (X-ray fluorescence), TGA (Thermo-gravimetric analyses), BET (Brunnauer, emmitt and teller analysis) and FTIR (Fourier Transform Infrared) analysis. Process variables optimization for biodiesel production were studied using RSM-CCD approach. The R 2 values were found to be 0.9592 and 0.9595, which show that the model was significantly fit with the experimental data. Maximum FAME conversion was 72% for the synthesized catalyst under optimum process conditions (the four parameters studied in the acid catalyzed esterification of beef tallow resulted in an optimum FFA of 0.60 at operating conditions of acid catalyst amount of 7.1%, methanol to oil ratio of 9:1, reaction temperature of 60 °C and a reaction time of 96 min. The obtained FFA from the actual experimental data showed a close correlation with the predicted FFA result where a predicted FFA of 0.61 was obtained. Components of FAME present in biodiesel was shown by the GCMS analysis. More research is needed on the effect of agitation speed, pressure of reacting mixtures and effect of alcohol and catalyst on process optimization.