Biodiesel synthesis over green catalyst: The effect of thermal treatment of CaO/Zeolite precursor on catalytic activity

Abstract

The green CaO/Zeolite catalyst for methanolysis of fatty oils was synthesized entirely from the waste materials. CaO derived from chicken eggshell was loaded onto fly ashbased zeolite catalyst carrier by the wet impregnation method using an alcohol solution. The effect of thermal activation at different temperatures ranging from 450 to 600 °C on catalytic activity was studied. The precursor and catalyst samples were characterized by XRD, FTIR, SEM, and Hg-porosimetry techniques. The catalytic tests were performed in a stirred batch reactor at the following reaction conditions: 60 °C - reaction temperature, 12:1 - methanol/oil molar ratio, and 4 wt% - catalyst concentration. The obtained results showed that the synthesized CaO/Zeolite catalyst has preserved alumosilicate framework-cancrinite type [1], with uniformly distributed calcium oxide (CaO) on its surface (Fig. 1c). It is shown that the catalyst sample calcinated at 550 °C exhibited the highest FAME content of 96.46%, which was achieved in 2 h (Fig. 2). Increasing temperature of calcination above 550 °C led to the formation of inactive calcium alumosilicate forms causing a decrease in the FAME content.