Transesterification of Pistacia chinensis oil for biodiesel catalyzed by CaO–CeO2 mixed oxides

This study investigates the use of CaO–CeO2 mixed oxides as solid base catalysts for the transesterification of Pistacia chinensis oil with methanol to produce biodiesel. These CaO–CeO2 mixed-oxide catalysts were prepared by an incipient wetness impregnation method and characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. The cerium improved the heterogeneous catalytic stability remarkably due to the defects induced by the substitution of Ca ions for Ce ions on the surface. The best catalyst was determined to be C0.15-973 (with a Ce/Ca molar ratio of 0.15 and having been calcined at 973 K), considering its catalytic and anti-leaching abilities. The effects of reaction parameters such as the methanol/oil molar ratio, the amount of catalyst amount and the reaction temperature were also investigated. For the C0.15-973 regenerated after five reuses, the biodiesel yield was 91%, which is slightly less than that of the fresh sample. The test results revealed that the CaO–CeO2 mixed oxides have good potential for use in the large-scale biodiesel production.