Production of novel biodiesel from transesterification over KF-modified Ca–Al hydrotalcite catalyst

Abstract

A series of KF-modified Ca–Al hydrotalcite (xKF/HTL-M) solid base catalysts was prepared in methanol, and characterized by thermogravimetry analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and carbon dioxide temperature-programmed desorption (CO₂-TPD). The catalytic activity was investigated in the transesterification of ethylene glycol monomethyl ether (EGME) with methyl laurate (ML) to produce a novel biodiesel of ethylene glycol monomethyl ether monolaurate (EGMEML). The effect of the mass content of KF and the main reaction parameters such as EGME to ML molar ratio, amount of catalyst, reaction time and temperature on the yield of EGMEML were examined. The results indicate that a new phase of KCaF₃ formed in xKF/HTL-M, and acted as the main active sites for the transesterification. In addition, xKF/HTL-M has excellent catalytic performance in the production of EGMEML. The highest yield of 97.7% was obtained over 24.7KF/HTL-M at EGME/ML molar ratio of 3.0, catalyst amount of 5 wt%, and reaction time of 4 h at 120 °C. Moreover, the catalyst displays a good stability and reutilization. A satisfactory yield of 90% was obtained after use for five consecutive cycles without significant deactivation. Finally, the activation energy (E_a) of the reaction of EGME with ML over 24.7KF/HTL-M was obtained as 27.11 kJ mol⁻¹.