Synthesis and catalytic activity of mesostructured KF/CaxAl2O(x+3) for the transesterification reaction to produce biodiesel

Abstract

A novel kind of highly efficient solid base, mesostructured KF/Ca_xAl₂O_(x+3), has been successfully fabricated via a new solvent-evaporation strategy followed by a KF impregnation process and the effects of the synthetic parameters of mesostructured KF/Ca_xAl₂O_(x+3) on the catalytic properties in the transesterification reaction of soybean oil with methanol for the production of a clean and green alternative fuel – biodiesel have been investigated in detail. It was found that the catalyst, 30KF/m-CaAl4(700)-700-3, with a Al/Ca molar ratio of 4, KF·2H₂O loading amount of 30%, activated at 700 °C for 3 h, was the most efficient catalyst among those synthesized in this study due to its high total active basicity and basic strength. Compared to the traditional solid basic catalyst CaO, under the optimized reaction condition, the reaction catalyzed by the prepared 30KF/m-CaAl4(700)-700-3 catalyst with the unique mesoporous structure and large amount of super basic sites showed much higher reaction rate and TOF value in the initial 1 h, a comparable biodiesel yield of about 98% in 5 h, and near 100% selectivity for FAME. Also importantly, the Ca leaching amount with 30KF/m-CaAl4(700)-700-3 is far lower than that with CaO and meets the EN14214 standard. Therefore, this engineered mesostructured KF/Ca_xAl₂O_(x+3) provides an efficient catalytic platform for a green biodiesel production process.