Solid base catalysis of calcium glyceroxide for a reaction to convert vegetable oil into its methyl esters

Abstract

When calcium oxide is employed for transesterification of vegetable oil at reflux of methanol, calcium oxide is turned into calcium glyceroxide by combining with glycerol of the by-product. As well as calcium oxide, calcium glyceroxide seemed to catalyze the vegetable oil transesterification. In the present paper, the solid base catalysis of calcium glyceroxide was investigated by IR spectroscopy using methanol as the molecular probe. The measured spectra indicated that calcium glyceroxide was combined with methanol at the temperature of 333 K. Chemical composition of the produced calcium compound was estimated at CH 3O-Ca-O(OH) 2C 3H 5. The IR spectrum of the calcium alkoxide indicated that hydrogen bond was formed among the glyceroxyl OH groups and methanol. Data from the soybean oil transesterification, which was carried out at 298 K, elucidated that the calcium alkoxide functioned as the solid base catalyst. At the same reaction temperature, calcium glyceroxide did not interact chemically with methanol, and sent out only the homogeneous catalysis.