Effect of Calcination Temperature of Musa sapientum Linn Peels as a Novel Biobased Heterogeneous Catalyst for Soybean Oil-derived Fatty Acid Methyl Ester Formation

Abstract

In the present study, a novel solid base catalyst derived from desert banana (Musa sapientum Linn) peels was used as a catalyst for biodiesel production. The catalyst was calcined at several temperatures between 550–650 °C under atmosphere pressure for 4 h. The composition, structure and texture of the calcined banana peel (CBP) catalysts were characterized by X-ray diffraction, thermogravimetric analysis, scanning electron microscopy with energy dispersive spectroscopy, X-ray fluorescence spectrophotometry, and Fourier-transform infrared spectroscopy analyses. The fatty acid profile of the feed soybean oil and the fatty acid methyl ester (FAME) product composition was analyzed using gas chromatography with flame ionization detection. The prepared catalysts were then applied for the catalytic transesterification of soybean oil with methanol under microwave-assisted heating to form FAME. The effect of the calcination temperature in the catalyst preparation, the catalyst loading level, reaction time, methanol: soybean oil molar ratio and catalyst reusability on the FAME yield were determined by univariate analysis. The CBP catalyst synthesized at 600 °C exhibited the highest catalytic activity, since the calcined ash was rich in K, P, Ca and Mg which formed a basic heterogenous catalyst at this calcination temperature. At the determined optimal reaction condition (1 wt.% catalyst loading level, 12:1 molar ratio of methanol: soybean oil, and a 2 min of reaction time under 300 W microwave irradiation) a FAME yield of 99.3% was obtained. Furthermore, the catalyst showed a good reusability with a biodiesel yield of more than 80.7% after four uses.