Calcium diglyceroxide synthesized by mechanochemical treatment, its characterization and application as catalyst for fatty acid methyl esters production

Abstract

In the present work, calcium diglyceroxide (CaDG) was synthesized by mechanochemical treatment of CaO dispersed in glycerol, and characterized by X-ray diffraction (XRD), thermal analysis (TGA/DTA), infrared spectroscopy (FTIR), and Hammett indicator method for base strength determination. The obtained CaDG was tested as a catalyst in the methanolysis of sunflower oil under different working conditions: catalyst amount, agitation speed, temperature and methanol to oil molar ratio. The main advantage of CaDG used as a catalyst in methanolysis is related to the initial rate of methanolysis. According to many previously reported data in literature the mass transfer resistance controls the overall rate of methanolysis, but it is not observed with CaDG used as catalyst. Recently developed kinetic model that describes the complex methanolysis process was successfully applied for this system and model parameters were determined, supporting the explanation of the physical effect of the CaDG catalyst on the reduction of mass transfer resistance and increasing the rate of methanolysis. The absence of mass transfer rate at the beginning of process is a consequence of the nature of the CaDG, which is adsorbed at the droplet interfaces between methanol and oil leading to the formation of fine dispersion of these two immiscible liquids.