Base Catalysts Derived from Hydrocalumite for the Transesterification of Sunflower Oil

This work investigates the use of a layered Ca-Al double hydroxide (hydrocalumite) as precursor, after its thermal activation, of base catalysts for the methanolysis of sunflower oil. Above 750 degrees C, hydrocalumite is transformed into a mixture of CaO and mayenite (Ca12Al14O33). Another Ca-Al material obtained under similar experimental conditions was also studied, but using the Ca/Al molar ratio of the mayenite, 12:14. A sunflower oil conversion of 97% has been reached with a methanol/oil molar ratio of 12:1, a reaction temperature of 60 degrees C, and 1 wt % of the CaAl-2:1 catalyst. This catalyst needs to be previously activated at 500 degrees C in helium atmosphere, which is an activation temperature at least 200 degrees C lower than that required to revert the CO2 positioning in bulk and supported CaO catalysts.