ABSTRACT
Biodiesel produced from oil crops raises up sustainability issues, being the use of arable lands the major drawback of such renewable fuel. Thus, alternative raw materials, such as non-edible animal fats and waste frying oils must be used. Biodiesel from waste frying oils, tallow and lard was produced over Ca based heterogeneous catalyst prepared using Ca rich scallop shells. In the tested conditions (methanol reflux temperature), the acidity and water content of low grade fats promoted a decrease of catalytic performances comparing with those obtained using soybean oil. Soap formation was observed in parallel with severe crystal-lographic modifications of catalyst: Ca diglyceroxide formation and amorphization. The use of isopropanol as co-solvent was able to improve the FAME yield reducing the soap formation. Additionally, isopropanol avoided modifications of catalyst during reaction, contributing to the catalyst stability. Glycerin phase quality was also improved in the presence of the co-solvent.
