In this study, Ca–Al mixed oxide produced from the thermal decomposition of a synthetic hydrocalumite was prepared and evaluated as a catalyst in the transesterification reaction for biodiesel production, using the following reagents: refined soybean oil, crude macauba kernel oil, methanol, and ethanol. The synthetic hydrocalumite and the mixed oxide were characterized by powder X-ray diffraction, thermogravimetry–differential scanning calorimetry coupled with mass spectrometry, specific surface area measurement, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and temperature-programmed desorption of CO2. The catalytic tests indicated that the reactions using methanol exhibited more favorable activity than those employing ethanol, regardless of the type of oil used (soybean or macauba). Ethanolysis produced better results for the higher-molar-mass oil (soybean), because of the effect of the ethanol cosolvent. The catalyst was efficient for transesterification, with conversions of 97% and 95% for soybean and macauba oil, respectively, after 1.5 h of reaction, under atmospheric pressure condition and reflux temperature.

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