New route for the synthesis of silica-supported calcium oxide catalyst in biodiesel production

Abstract

This research aims to investigate the role of silica as a support for CaO catalyst in 4 different aspects: determination of optimum parameters, tolerance of water and FFA content, leaching and kinetics evaluation, and reusability of catalyst. Silica was extracted from rice husk by ion exchange method and subsequently impregnated with CaO. The experimental results showed that the supported catalysts exhibit excellent catalytic activity in transesterification of waste cooking oil with high yield of biodiesel, comparable to that of CaO catalyst. This is due to the fact that catalyst with higher surface area produces higher biodiesel yield. The presence of water did not have significant effect on the performance of supported catalysts, as silica can act as catalyst to esterify the FFA. Furthermore, silica support offered the greatest extent of leaching minimization of CaO and it has been proved that the calcium leached species was insignificant in transesterification reaction. Reusability study suggests that the synthesized catalysts can be recycled up for 8 successive runs. In conclusion, employing calcium rich wastes derived CaO impregnated with silica as catalyst showed good potential in catalytic applications with high economic benefits.