Production of biodiesel from waste frying oil using waste calcareous-onyx as unique esterification and transesterification catalytic source
Jorge Cruz-Mérida, Grisel Corro, Fortino Bañuelos, Daniel Montalvo, Umapada Pal
Abstract
Biodiesel was produced from waste frying oil (WFO) using waste calcareous-onyx as catalyst. The free fatty acids (FFAs) present in WFO were first esterified with methanol using calcareous-onyx powder calcined at 700 °C (Onyx-700), and the triglycerides transesterification was catalyzed by waste calcareous-onyx powder calcined at 1100 °C (Onyx-1100). Both catalysts were highly active for 5 consecutive reaction runs. DRX and FTIR analyses revealed that Onyx-700 was composed of CaCO3, with traces of CaO in calcite pseudomorph, which accelerates methanol adsorption. Onyx-700 prevents reactions between FFAs and CaO, avoiding calcium soap generation. Onyx-1100, which was basically CaO, enhanced triglyceride transesterification process.