Chiang Mai Journal of Science

Nanoscale CaO was demonstrated as a high activity and selectivity catalyst for transesterification of crude palm oil. The CaO catalyst with particle sizes diameter of 12±4 nm and specific surface areas 70 m2g-1 was synthesized by sol-gel process. Photoluminesence spectra clearly demonstrated high number of oxide ions at low coordination sites (edges and corners) of nano CaO. FT-IR spectra showed that oxide ions at low coordination sites can accelerate deprotonation of methanol and glycerol at room temperature. Highly reactive calcium methoxide and calcium glyceroxide species were formed at room temperature leading to high reaction kinetic of transesterification. A high yield of fatty acid methyl esters (% FAME) of 98% was achieved within 30 min with 2.0 wt% of nano CaO catalyst. High formation of calcium methoxide at room temperature leads to high selectivity of transesterification leading to decrease in the level of calcium soap from saponification of free fatty acid. These active species promote transesterification in the forward direction, increasing the rate of conversion and reduction of soap formation.