Coal fly ash supported ZnO catalyzed transesterification of Jatropha curcas oil: Optimization by response surface methodology

Abstract

Herein, a zinc oxide based coal fly ash (ZnO-CFA) composite as heterogeneous catalyst was formulated and explored for transesterification of non-edible oil (Jatropha curcas oil, JCO). The as-synthesized catalyst was analyzed to gain insights into its properties using various characterization techniques (EDX, FTIR, TEM, XRD and BET). The solid catalyst’s ability to catalyze the methanolysis reaction was investigated and optimized at varying reaction temperature, methanol/JCO molar ratio and catalyst dosage using Box-Behnken design. Predicted values of biodiesel yield were found to be in agreement with the experimental values obtained R2=0.9751andAdj.R2=0.9431. It was determined that optimum transesterification process conditions of 60.4 °C reaction temperature, 11.8:1 methanol/JCO molar ratio and 1.63 wt% catalyst loading resulted in biodiesel yield and FAME content of 91.08 ± 0.06 % and 97.22 %, respectively. Additionally, the produced biodiesel at the optimum conditions was shown to be conformed to ASTM standard. The ZnO-CFA catalyst was simple to synthesize and handle, eliminating the need for costly aluminosilicate-based catalysts in biofuel synthesis. It was also simple to separate from the product stream and could be recycled up to four times.

Keywords

• Biodiesel
• ZnO
• Fly ash
• Transesterification
• Catalyst
• Optimization