FUEL 38

Calcined Mg-Al hydrotalcite (CHT) catalysts have been studied for the conversion of lipid feedstocks, such as poultry fat, to biodiesel. CHT catalysts showed high catalytic activity for triglyceride (TG) transesterification with methanol without signs of catalyst leaching. Catalyst activity was affected by pretreatment and operating conditions. The optimum HT calcination temperature was 550°C. Methanol had to be pre-contacted with the catalyst before reaction; otherwise, catalyst activity was hindered probably due to the strong adsorption of TG molecules on catalytic sites. Reaction parameters like temperature (60-120°C) and methanol-to-TG molar ratio (6:1-60:1) positively affected the reaction rate. Catalyst deactivation was significant during the first reaction cycle probably due to deactivation of the strongest base sites. Catalyst activity, however, remained stable during subsequent reaction cycles. Catalyst activity was completely restored by re-calcination in air. Probable chemical pathways leading to catalyst deactivation will be discussed.