Comparison of catalytic activities of Ca-based catalysts from waste in biodiesel production

It is very important to produce biodiesel using heterogeneous catalysts synthesized from wastes, because this process involves the beneficial use of waste. It does not involve clean water consumption and wastewater discharge during product purification. In this study, heterogeneous catalysts were synthesized by calcination from different calcium-based wastes such as waste eggshell, marble dust, sugar industry waste, seashells, and waste ceramic tiles. Catalysts prepared from wastes were characterized by XRD, BET, TGA, and SEM-EDX analysis. Sunflower biodiesel by transesterification was produced in the same reaction conditions (5 wt.% catalyst amount and 15: 1 methanol to oil molar ratio at 60 degrees C for 2 h) using each prepared catalyst. In order to compare the catalytic activities for biodiesel production with the catalysts prepared from different wastes, the fatty acid methyl ester (FAME) yields and some fuel properties of the biodiesel samples were analyzed. Experimental results indicate that the biodiesel samples produced with all catalysts, except waste tiles, had FAME yields above 73% and their fuel properties complied with both EN 14214 and ASTM D6751 standards. The highest FAME yields were achieved with marble dust (89.14%) and sugar industry waste (87.64%) catalysts. Moreover, these yields were almost the same as those achieved with commercial CaCO3 (90%). According to the results of the study, for the production of biodiesel under the same reaction conditions, the waste tile catalyst showed no catalytic activity, whereas marble dust and sugar industry waste catalysts had the highest catalytic activity.