The activity and stability of CeO₂@CaO catalysts for the production of biodiesel

Abstract

A novel CeO₂@CaO catalyst was prepared <i>via</i> a hydrothermal method. The physicochemical properties and morphologies of the prepared CeO₂@CaO catalysts were characterized by X-ray diffraction, N₂ physisorption, CO₂ temperature-programmed desorption, X-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive X-ray analysis. It was found that the prepared CeO₂@CaO catalyst had a distinct core-shell structure. The catalytic activity of the CeO₂@CaO sample as a heterogeneous catalyst for the transesterification of soybean oil to produce biodiesel has been studied. The results showed that the optimum yield of biodiesel can reach 98% over the CeO₂@CaO-60 catalyst under the reaction conditions of 3 wt% catalyst, methanol to oil molar ratio of 6 : 1, reaction temperature of 70 °C and reaction time of 6 h. Stability tests indicated that the biodiesel yield can reach more than 80% even after 9 reaction cycles due to the strong synergic interaction between CaO and CeO₂.