Nanocatalysts of Sulfated Zirconia and Calcium Oxide/Zirconia for Microwave-Assisted Biodiesel Synthesis from Castor Oil

Abstract

Nanocatalysts of sulfated zirconia (SZ) and CaO/zirconia for microwave assisted-biodiesel synthesis from castor oil have been successfully prepared. The aim of the research was to determine the effectiveness and the selectivity of catalysts in biodiesel production. The sulfated zirconia catalyst was prepared by the wet impregnation method while the calcium oxide/zirconia catalyst was prepared through the wet impregnation by microwave-assisted method. The catalysts were used for the esterification and transesterification reaction with the highest acidity and the basicity value of 7.16 mmol NH3 g-1, 87.76 mmol HCl g-1, respectively. The acidity and basicity of the catalysts are directly related to the catalyst active site in the esterification and transesterification process. The results showed that catalyst 0.5 M SZ 500 and 1: 0.2 CaO/ZrO2 800 had excellent stability that can be seen from their high crystallinity and large surface area. The biodiesel products characterized by 1H-NMR, GC-MS and Bomb calorimeter also showed excellent results. After purification, 1H-NMR result shows the conversion of castor oil into methyl ester is close to 100%. This was supported by GC-MS where the highest area of methyl ester is 93.91% of methyl ricinoleate.