Montmorillonite-supported KF/CaO: a new solid base catalyst for biodiesel production

Biodiesel is an alternative to petroleum-derived diesel fuel; development of a high-efficiency base catalyst to be used in heterogeneous biodiesel production is still a challenge. In this paper, a novel solid base catalyst, KF- and CaO-supported montmorillonite (KCa/MMT) was successfully synthesized by a facile impregnation method, and used for producing biodiesel in transesterification of commercial soybean oil with methanol. The catalysts were characterized by X-ray diffraction, carbon dioxide temperature-programmed desorption and scanning electron microscopy. Effects of the parameters, such as the loading amount of KF, the amount of KCa/MMT, and the methanol to oil molar ratios, on the yield of biodiesel were investigated. A maximum biodiesel yield of 98 % was obtained under the optimal reaction conditions. The separated catalyst can be directly used in the next round of reactions and gave a satisfactory yield. Furthermore, analysis of the catalyst's tolerance to oil-containing water or free fatty acids, and a kinetic study were also carried out. Koros–Nowak tests were designed and conducted, and it was proven that the heat and mass transfer were not limited by the reaction rate.