Preparation of Novel Ethylene Glycol Monomethyl Ether Fatty Acid Monoester Biodiesel Using Calcined Sodium Silicate

A series of ethylene glycol monomethyl ether (EGME) fatty acid monoesters were prepared by the transesterification of different fatty acid methyl esters (FAMEs) with EGME. A solid basic catalyst, namely, calcined sodium silicate, was used. Various parameters, such as the calcination temperature, amount of catalyst, molar ratio of FAME/EGME, reaction temperature, and time on the yield of EGMEML (ML = methyl laurate), were optimized; the reusability of calcined sodium silicate was also examined. Calcined sodium silicate was also used as a catalyst for examining the catalytic activity of soybean oil biodiesel with EGME. Thermogravimetry, X-ray diffraction, carbon dioxide temperature-programmed desorption, Fourier transform infrared spectroscopy, and scanning electron microscopy were employed to characterize the properties of calcined sodium silicate. The results indicated that calcined sodium silicate was effective for the synthesis of novel biodiesel by FAMEs, with EGME as reactants. Centrifugation and decantation were used to separate the solid basic catalyst from the reaction system easily. The separated catalyst can be directly used in the next round of reactions for at least 3 cycles and gave a satisfied yield. A maximum yield of EGME fatty acid monoester of above 90.0% was obtained under the optimal reaction conditions. Furthermore, the reaction kinetic of the transesterification of ML with EGME was investigated. It revealed that the reaction follows second-order kinetics; the activation energy E-a and pre-exponential factor A were 50.05 kJ mol(-1) and 1.07 X 10(4) L min(-1) mol(-1) by the calculation, respectively. Koros-Nowak tests were designed and conducted, and it was proven that the heat and mass transfer, were not limited by the reaction rate.