Solid base CaO–CeO2 mixed oxide catalysts have been synthesized via wet impregnation method and
characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis,
temperature-programmed desorption of CO2 (TPD-CO2) and scanning electron microscopy (SEM). The
catalytic activity was determined by transesterification of palm oil. Optimum biodiesel yield, 95%, was
achieved by 50Ca–Ce catalyst under the reaction conditions of 5 wt.% of catalyst, methanol to oil molar
ratio of 12:1, reaction temperature of 65 C and reaction time of 4 h. The high catalytic activity (95%)
of 50Ca–Ce catalyst may be due to strong basicity and high BET surface area, which indicate more number
of active sites on the catalyst surface for transesterification process. Besides, 50Ca–Ce catalyst showed
better reusability than the bulk CaO where it can be reused up to 6 times without a significant loss of
catalytic activity (>80%). The lixiviation of CaO active phase was greatly reduced with the presence of
strong synergic interaction between CaO and CeO2. Deactivation of the catalyst was mainly due to the
leaching of CaO active phase into the methanolic solution and pore-filling by fatty acid or glycerol.