Effectiveness of Eggshells as Natural Heterogeneous Catalysts for Transesterification of Rapeseed Oil with Methanol

Abstract

Heterogeneous catalysis has an advantage of easy separation of the catalyst after biodiesel is produced. CaO is known to be an efficient heterogeneous catalyst for biodiesel production. Taking into account that CaO is a key component of eggshells, the effectiveness of eggshells as a heterogeneous catalyst for rapeseed oil transesterification with methanol was investigated and optimal conditions of biodiesel production were determined applying RSM methodology. The influence of three independent variables on ester content was analyzed and a quadratic model was created. It was determined that this model is statistically significant. The optimum transesterification conditions when eggshells are used as a heterogeneous catalyst, and the process temperature of 64◦C, were determined as: the methanol-to-oil molar ratio 10.93:1; the catalyst amount 6.80 wt%; the reaction duration 9.48 h. The ester yield of 97.79 wt% was obtained under these conditions.